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id="toc-Neural-network_mixing-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Context_modeling" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Context_modeling"> <div class="vector-toc-text"> <span class="vector-toc-numb">1.4</span> <span>Context modeling</span> </div> </a> <ul id="toc-Context_modeling-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Text_preprocessing" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Text_preprocessing"> <div class="vector-toc-text"> <span class="vector-toc-numb">1.5</span> <span>Text preprocessing</span> </div> </a> <ul id="toc-Text_preprocessing-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Comparison" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Comparison"> <div class="vector-toc-text"> <span class="vector-toc-numb">2</span> <span>Comparison</span> </div> </a> <ul id="toc-Comparison-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-History" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#History"> <div class="vector-toc-text"> <span class="vector-toc-numb">3</span> <span>History</span> </div> </a> <button aria-controls="toc-History-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle History subsection</span> </button> <ul id="toc-History-sublist" class="vector-toc-list"> <li id="toc-Hutter_Prizes" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Hutter_Prizes"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.1</span> <span>Hutter Prizes</span> </div> </a> <ul id="toc-Hutter_Prizes-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-PAQ_derivations" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#PAQ_derivations"> <div class="vector-toc-text"> <span class="vector-toc-numb">4</span> <span>PAQ derivations</span> </div> </a> <ul id="toc-PAQ_derivations-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-See_also" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#See_also"> <div class="vector-toc-text"> <span class="vector-toc-numb">5</span> <span>See also</span> </div> </a> <ul id="toc-See_also-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-References" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#References"> <div class="vector-toc-text"> <span class="vector-toc-numb">6</span> <span>References</span> </div> </a> <ul id="toc-References-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Further_reading" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Further_reading"> <div class="vector-toc-text"> <span class="vector-toc-numb">7</span> <span>Further reading</span> </div> </a> <ul id="toc-Further_reading-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-External_links" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#External_links"> <div class="vector-toc-text"> <span class="vector-toc-numb">8</span> <span>External links</span> </div> </a> <ul id="toc-External_links-sublist" class="vector-toc-list"> </ul> </li> </ul> </div> </div> </nav> </div> </div> <div class="mw-content-container"> <main id="content" class="mw-body"> <header class="mw-body-header vector-page-titlebar"> <nav aria-label="Contents" class="vector-toc-landmark"> <div id="vector-page-titlebar-toc" class="vector-dropdown vector-page-titlebar-toc vector-button-flush-left" > <input type="checkbox" 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id="p-lang-btn-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-p-lang-btn" class="vector-dropdown-checkbox mw-interlanguage-selector" aria-label="Go to an article in another language. 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hreflang="es" data-title="PAQ" data-language-autonym="Español" data-language-local-name="Spanish" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/PAQ_(logiciel)" title="PAQ (logiciel) – French" lang="fr" hreflang="fr" data-title="PAQ (logiciel)" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-it mw-list-item"><a href="https://it.wikipedia.org/wiki/PAQ_(formato_di_file)" title="PAQ (formato di file) – Italian" lang="it" hreflang="it" data-title="PAQ (formato di file)" data-language-autonym="Italiano" data-language-local-name="Italian" class="interlanguage-link-target"><span>Italiano</span></a></li><li class="interlanguage-link interwiki-ja mw-list-item"><a href="https://ja.wikipedia.org/wiki/PAQ" title="PAQ – Japanese" lang="ja" hreflang="ja" data-title="PAQ" data-language-autonym="日本語" data-language-local-name="Japanese" class="interlanguage-link-target"><span>日本語</span></a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/PAQ" title="PAQ – Russian" lang="ru" hreflang="ru" data-title="PAQ" data-language-autonym="Русский" data-language-local-name="Russian" class="interlanguage-link-target"><span>Русский</span></a></li><li class="interlanguage-link interwiki-uk mw-list-item"><a href="https://uk.wikipedia.org/wiki/PAQ" title="PAQ – Ukrainian" lang="uk" hreflang="uk" data-title="PAQ" data-language-autonym="Українська" data-language-local-name="Ukrainian" class="interlanguage-link-target"><span>Українська</span></a></li> </ul> <div class="after-portlet after-portlet-lang"><span class="wb-langlinks-edit wb-langlinks-link"><a href="https://www.wikidata.org/wiki/Special:EntityPage/Q1465895#sitelinks-wikipedia" title="Edit interlanguage links" class="wbc-editpage">Edit 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this page [j]" accesskey="j"><span>What links here</span></a></li><li id="t-recentchangeslinked" class="mw-list-item"><a href="/wiki/Special:RecentChangesLinked/PAQ" rel="nofollow" title="Recent changes in pages linked from this page [k]" accesskey="k"><span>Related changes</span></a></li><li id="t-upload" class="mw-list-item"><a href="/wiki/Wikipedia:File_Upload_Wizard" title="Upload files [u]" accesskey="u"><span>Upload file</span></a></li><li id="t-specialpages" class="mw-list-item"><a href="/wiki/Special:SpecialPages" title="A list of all special pages [q]" accesskey="q"><span>Special pages</span></a></li><li id="t-permalink" class="mw-list-item"><a href="/w/index.php?title=PAQ&oldid=1258855027" title="Permanent link to this revision of this page"><span>Permanent link</span></a></li><li id="t-info" class="mw-list-item"><a href="/w/index.php?title=PAQ&action=info" title="More information about this page"><span>Page information</span></a></li><li id="t-cite" class="mw-list-item"><a href="/w/index.php?title=Special:CiteThisPage&page=PAQ&id=1258855027&wpFormIdentifier=titleform" title="Information on how to cite this page"><span>Cite this page</span></a></li><li id="t-urlshortener" class="mw-list-item"><a href="/w/index.php?title=Special:UrlShortener&url=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FPAQ"><span>Get shortened URL</span></a></li><li id="t-urlshortener-qrcode" class="mw-list-item"><a href="/w/index.php?title=Special:QrCode&url=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FPAQ"><span>Download QR code</span></a></li> </ul> </div> </div> <div id="p-coll-print_export" class="vector-menu mw-portlet mw-portlet-coll-print_export" > <div class="vector-menu-heading"> Print/export </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="coll-download-as-rl" class="mw-list-item"><a href="/w/index.php?title=Special:DownloadAsPdf&page=PAQ&action=show-download-screen" title="Download this page as a PDF file"><span>Download as PDF</span></a></li><li id="t-print" class="mw-list-item"><a href="/w/index.php?title=PAQ&printable=yes" title="Printable version of this page [p]" accesskey="p"><span>Printable version</span></a></li> </ul> </div> </div> <div id="p-wikibase-otherprojects" class="vector-menu mw-portlet mw-portlet-wikibase-otherprojects" > <div class="vector-menu-heading"> In other projects </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="wb-otherproject-link wb-otherproject-commons mw-list-item"><a href="https://commons.wikimedia.org/wiki/Category:PAQ" hreflang="en"><span>Wikimedia Commons</span></a></li><li id="t-wikibase" class="wb-otherproject-link wb-otherproject-wikibase-dataitem mw-list-item"><a href="https://www.wikidata.org/wiki/Special:EntityPage/Q1465895" title="Structured data on this page hosted by Wikidata [g]" accesskey="g"><span>Wikidata item</span></a></li> </ul> </div> </div> </div> </div> </div> </div> </nav> </div> </div> </div> <div class="vector-column-end"> <div class="vector-sticky-pinned-container"> <nav class="vector-page-tools-landmark" aria-label="Page tools"> <div id="vector-page-tools-pinned-container" class="vector-pinned-container"> </div> </nav> <nav class="vector-appearance-landmark" aria-label="Appearance"> <div id="vector-appearance-pinned-container" class="vector-pinned-container"> <div id="vector-appearance" class="vector-appearance vector-pinnable-element"> <div class="vector-pinnable-header vector-appearance-pinnable-header vector-pinnable-header-pinned" data-feature-name="appearance-pinned" data-pinnable-element-id="vector-appearance" data-pinned-container-id="vector-appearance-pinned-container" data-unpinned-container-id="vector-appearance-unpinned-container" > <div class="vector-pinnable-header-label">Appearance</div> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-pin-button" data-event-name="pinnable-header.vector-appearance.pin">move to sidebar</button> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-unpin-button" data-event-name="pinnable-header.vector-appearance.unpin">hide</button> </div> </div> </div> </nav> </div> </div> <div id="bodyContent" class="vector-body" aria-labelledby="firstHeading" data-mw-ve-target-container> <div class="vector-body-before-content"> <div class="mw-indicators"> </div> <div id="siteSub" class="noprint">From Wikipedia, the free encyclopedia</div> </div> <div id="contentSub"><div id="mw-content-subtitle"></div></div> <div id="mw-content-text" class="mw-body-content"><div class="mw-content-ltr mw-parser-output" lang="en" dir="ltr"><div class="shortdescription nomobile noexcerpt noprint searchaux" style="display:none">Series of data compression archivers</div> <style data-mw-deduplicate="TemplateStyles:r1236090951">.mw-parser-output .hatnote{font-style:italic}.mw-parser-output div.hatnote{padding-left:1.6em;margin-bottom:0.5em}.mw-parser-output .hatnote i{font-style:normal}.mw-parser-output .hatnote+link+.hatnote{margin-top:-0.5em}@media print{body.ns-0 .mw-parser-output .hatnote{display:none!important}}</style><div role="note" class="hatnote navigation-not-searchable">For other uses, see <a href="/wiki/PAQ_(disambiguation)" class="mw-disambig" title="PAQ (disambiguation)">PAQ (disambiguation)</a>.</div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">For the unrelated <code>PAQ.EXE</code> compressor for DOS, see <a href="/wiki/Quantum_compression_(disambiguation)" class="mw-redirect mw-disambig" title="Quantum compression (disambiguation)">Quantum compression</a>.</div> <style data-mw-deduplicate="TemplateStyles:r1251242444">.mw-parser-output .ambox{border:1px solid #a2a9b1;border-left:10px solid #36c;background-color:#fbfbfb;box-sizing:border-box}.mw-parser-output .ambox+link+.ambox,.mw-parser-output .ambox+link+style+.ambox,.mw-parser-output .ambox+link+link+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+style+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+link+.ambox{margin-top:-1px}html body.mediawiki .mw-parser-output .ambox.mbox-small-left{margin:4px 1em 4px 0;overflow:hidden;width:238px;border-collapse:collapse;font-size:88%;line-height:1.25em}.mw-parser-output .ambox-speedy{border-left:10px solid #b32424;background-color:#fee7e6}.mw-parser-output .ambox-delete{border-left:10px solid #b32424}.mw-parser-output .ambox-content{border-left:10px solid #f28500}.mw-parser-output .ambox-style{border-left:10px solid #fc3}.mw-parser-output .ambox-move{border-left:10px solid #9932cc}.mw-parser-output .ambox-protection{border-left:10px solid #a2a9b1}.mw-parser-output .ambox .mbox-text{border:none;padding:0.25em 0.5em;width:100%}.mw-parser-output .ambox .mbox-image{border:none;padding:2px 0 2px 0.5em;text-align:center}.mw-parser-output .ambox .mbox-imageright{border:none;padding:2px 0.5em 2px 0;text-align:center}.mw-parser-output .ambox .mbox-empty-cell{border:none;padding:0;width:1px}.mw-parser-output .ambox .mbox-image-div{width:52px}@media(min-width:720px){.mw-parser-output .ambox{margin:0 10%}}@media print{body.ns-0 .mw-parser-output .ambox{display:none!important}}</style><table class="box-More_footnotes_needed plainlinks metadata ambox ambox-style ambox-More_footnotes_needed" role="presentation"><tbody><tr><td class="mbox-image"><div class="mbox-image-div"><span typeof="mw:File"><span><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/a/a4/Text_document_with_red_question_mark.svg/40px-Text_document_with_red_question_mark.svg.png" decoding="async" width="40" height="40" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/a/a4/Text_document_with_red_question_mark.svg/60px-Text_document_with_red_question_mark.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/a/a4/Text_document_with_red_question_mark.svg/80px-Text_document_with_red_question_mark.svg.png 2x" data-file-width="48" data-file-height="48" /></span></span></div></td><td class="mbox-text"><div class="mbox-text-span">This article includes a list of <a href="/wiki/Wikipedia:Citing_sources#General_references" title="Wikipedia:Citing sources">general references</a>, but <b>it lacks sufficient corresponding <a href="/wiki/Wikipedia:Citing_sources#Inline_citations" title="Wikipedia:Citing sources">inline citations</a></b>.<span class="hide-when-compact"> Please help to <a href="/wiki/Wikipedia:WikiProject_Reliability" title="Wikipedia:WikiProject Reliability">improve</a> this article by <a href="/wiki/Wikipedia:When_to_cite" title="Wikipedia:When to cite">introducing</a> more precise citations.</span> <span class="date-container"><i>(<span class="date">March 2011</span>)</i></span><span class="hide-when-compact"><i> (<small><a href="/wiki/Help:Maintenance_template_removal" title="Help:Maintenance template removal">Learn how and when to remove this message</a></small>)</i></span></div></td></tr></tbody></table> <figure typeof="mw:File/Thumb"><a href="/wiki/File:Paq8o_Sample_Session.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/d/d2/Paq8o_Sample_Session.png/500px-Paq8o_Sample_Session.png" decoding="async" width="500" height="76" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/d/d2/Paq8o_Sample_Session.png 1.5x" data-file-width="565" data-file-height="86" /></a><figcaption>A sample session of PAQ8O</figcaption></figure> <p><b>PAQ</b> is a series of <a href="/wiki/Lossless_data_compression" class="mw-redirect" title="Lossless data compression">lossless data compression</a> archivers that have gone through collaborative development to top rankings on several benchmarks measuring compression ratio (although at the expense of speed and memory usage). Specialized versions of PAQ have won the <a href="/wiki/Hutter_Prize" title="Hutter Prize">Hutter Prize</a> and the <a href="/wiki/Calgary_Challenge" class="mw-redirect" title="Calgary Challenge">Calgary Challenge</a>.<sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> PAQ is <a href="/wiki/Free_software" title="Free software">free software</a> distributed under the <a href="/wiki/GNU_General_Public_License" title="GNU General Public License">GNU General Public License</a>.<sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="Algorithm">Algorithm</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=PAQ&action=edit&section=1" title="Edit section: Algorithm"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>PAQ uses a <a href="/wiki/Context_mixing" title="Context mixing">context mixing</a> algorithm. Context mixing is related to <a href="/wiki/Prediction_by_partial_matching" title="Prediction by partial matching">prediction by partial matching</a> (PPM) in that the compressor is divided into a predictor and an <a href="/wiki/Arithmetic_code" class="mw-redirect" title="Arithmetic code">arithmetic coder</a>, but differs in that the next-symbol prediction is computed using a weighted combination of probability estimates from a large number of models conditioned on different contexts. Unlike PPM, a context doesn't need to be contiguous. Most PAQ versions collect next-symbol statistics for the following contexts: </p> <ul><li><a href="/wiki/N-gram" title="N-gram"><i>n</i>-grams</a>; the context is the last <var style="padding-right: 1px;">n</var> bytes before the predicted symbol (as in PPM);</li> <li>whole-word <i>n</i>-grams, ignoring case and nonalphabetic characters (useful in text files);</li> <li>"sparse" contexts, for example, the second and fourth bytes preceding the predicted symbol (useful in some binary formats);</li> <li>"analog" contexts, consisting of the high-order bits of previous 8- or 16-bit words (useful for multimedia files);</li> <li>two-dimensional contexts (useful for images, tables, and spreadsheets); the row length is determined by finding the stride length of repeating byte patterns;</li> <li>specialized models, such as <a href="/wiki/X86" title="X86">x86</a> executables, <a href="/wiki/Windows_Bitmap" class="mw-redirect" title="Windows Bitmap">BMP</a>, <a href="/wiki/TIFF" title="TIFF">TIFF</a>, or <a href="/wiki/JPEG" title="JPEG">JPEG</a> images; these models are active only when the particular file type is detected.</li></ul> <p>All PAQ versions predict and compress one bit at a time, but differ in the details of the models and how the predictions are combined and postprocessed. Once the next-bit probability is determined, it is encoded by <a href="/wiki/Arithmetic_coding" title="Arithmetic coding">arithmetic coding</a>. There are three methods for combining predictions, depending on the version: </p> <ul><li>In PAQ1 through PAQ3, each prediction is represented as a pair of bit counts <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle (n_{0},n_{1})}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mo stretchy="false">(</mo> <msub> <mi>n</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>0</mn> </mrow> </msub> <mo>,</mo> <msub> <mi>n</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>1</mn> </mrow> </msub> <mo stretchy="false">)</mo> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle (n_{0},n_{1})}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/2f5ee4726653a66ed72fe6064be0525c5f36e3bc" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:7.741ex; height:2.843ex;" alt="{\displaystyle (n_{0},n_{1})}"></span>. These counts are combined by weighted summation, with greater weights given to longer contexts.</li> <li>In PAQ4 through PAQ6, the predictions are combined as before, but the weights assigned to each model are adjusted to favor the more accurate models.</li> <li>In PAQ7 and later, each model outputs a probability rather than a pair of counts. The probabilities are combined using an <a href="/wiki/Artificial_neural_network" class="mw-redirect" title="Artificial neural network">artificial neural network</a>.</li></ul> <p>PAQ1SSE and later versions postprocess the prediction using secondary symbol estimation (SSE). The combined prediction and a small context are used to look up a new prediction in a table. After the bit is encoded, the table entry is adjusted to reduce the prediction error. SSE stages can be pipelined with different contexts or computed in parallel with the outputs averaged. </p> <div class="mw-heading mw-heading3"><h3 id="Arithmetic_coding">Arithmetic coding</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=PAQ&action=edit&section=2" title="Edit section: Arithmetic coding"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>A string <i>s</i> is compressed to the shortest byte string representing a base-256 <a href="/wiki/Big-endian" class="mw-redirect" title="Big-endian">big-endian</a> number <i>x</i> in the range [0, 1] such that P(<i>r</i> < <i>s</i>) ≤ <i>x</i> < P(<i>r</i> ≤ <i>s</i>), where P(<i>r</i> < <i>s</i>) is the probability that a random string <i>r</i> with the same length as <i>s</i> will be <a href="/wiki/Lexicographical_order" class="mw-redirect" title="Lexicographical order">lexicographically</a> less than <i>s</i>. It is always possible to find an <i>x</i> such that the length of <i>x</i> is at most one byte longer than the <a href="/wiki/Noisy-channel_coding_theorem" title="Noisy-channel coding theorem">Shannon limit</a>, −log<sub>2</sub>P(<i>r</i> = <i>s</i>) bits. The length of <i>s</i> is stored in the archive header. </p><p>The <a href="/wiki/Arithmetic_coding" title="Arithmetic coding">arithmetic coder</a> in PAQ is implemented by maintaining for each prediction a lower and upper bound on <i>x</i>, initially [0, 1]. After each prediction, the current range is split into two parts in proportion to P(0) and P(1), the probability that the next bit of <i>s</i> will be a 0 or 1 respectively, given the previous bits of <i>s</i>. The next bit is then encoded by selecting the corresponding subrange to be the new range. </p><p>The number <i>x</i> is decompressed back to string <i>s</i> by making an identical series of bit predictions (since the previous bits of <i>s</i> are known). The range is split as with compression. The portion containing <i>x</i> becomes the new range, and the corresponding bit is appended to <i>s</i>. </p><p>In PAQ, the lower and upper bounds of the range are represented in three parts. The most significant base-256 digits are identical, so they can be written as the leading bytes of <i>x</i>. The next 4 bytes are kept in memory, such that the leading byte is different. The trailing bits are assumed to be all zeros for the lower bound and all ones for the upper bound. Compression is terminated by writing one more byte from the lower bound. </p> <div class="mw-heading mw-heading3"><h3 id="Adaptive_model_weighting">Adaptive model weighting</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=PAQ&action=edit&section=3" title="Edit section: Adaptive model weighting"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>In PAQ versions through PAQ6, each model maps a set of distinct contexts to a pair of counts, <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle n_{0}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>n</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>0</mn> </mrow> </msub> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle n_{0}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/63584d203ecb012a7bcb90f422408bbfe4018956" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:2.449ex; height:2.009ex;" alt="{\displaystyle n_{0}}"></span>, a count of zero bits, and <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle n_{1}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>n</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>1</mn> </mrow> </msub> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle n_{1}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/ee784b70e772f55ede5e6e0bdc929994bff63413" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:2.449ex; height:2.009ex;" alt="{\displaystyle n_{1}}"></span>, a count of 1 bits. In order to favor recent history, half of the count over 2 is discarded when the opposite bit is observed. For example, if the current state associated with a context is <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle (n_{0},n_{1})=(12,3)}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mo stretchy="false">(</mo> <msub> <mi>n</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>0</mn> </mrow> </msub> <mo>,</mo> <msub> <mi>n</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>1</mn> </mrow> </msub> <mo stretchy="false">)</mo> <mo>=</mo> <mo stretchy="false">(</mo> <mn>12</mn> <mo>,</mo> <mn>3</mn> <mo stretchy="false">)</mo> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle (n_{0},n_{1})=(12,3)}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/cb13e0b206cb2c1400b282dbce4f9039983bc8a4" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:17.17ex; height:2.843ex;" alt="{\displaystyle (n_{0},n_{1})=(12,3)}"></span> and a 1 is observed, then the counts are updated to (7, 4). </p><p>A bit is arithmetically coded with space proportional to its probability, either P(1) or P(0) = 1 − P(1). The probabilities are computed by weighted addition of the 0 and 1 counts: </p> <ul><li><i>S</i><sub>0</sub> = Σ<sub><i>i</i></sub> <i>w<sub>i</sub></i> <i>n</i><sub>0<i>i</i></sub>,</li> <li><i>S</i><sub>1</sub> = Σ<sub><i>i</i></sub> <i>w<sub>i</sub></i> <i>n</i><sub>1<i>i</i></sub>,</li> <li><i>S</i> = <i>S</i><sub>0</sub> + <i>S</i><sub>1</sub>,</li> <li>P(0) = <i>S</i><sub>0</sub> / <i>S</i>,</li> <li>P(1) = <i>S</i><sub>1</sub> / <i>S</i>,</li></ul> <p>where <i>w<sub>i</sub></i> is the weight of the <i>i</i>-th model. Through PAQ3, the weights were fixed and set in an ad-hoc manner. (Order-<i>n</i> contexts had a weight of <i>n</i><sup>2</sup>.) Beginning with PAQ4, the weights were adjusted adaptively in the direction that would reduce future errors in the same context set. If the bit to be coded is <i>y</i>, then the weight adjustment is: </p> <ul><li><i>n<sub>i</sub></i> = <i>n</i><sub>0<i>i</i></sub> + <i>n</i><sub>1<i>i</i></sub>,</li> <li>error = <i>y</i> – P(1),</li> <li><i>w<sub>i</sub></i> ← <i>w<sub>i</sub></i> + [(<i>S</i> <i>n</i><sub>1<i>i</i></sub> − <i>S</i><sub>1</sub> <i>n<sub>i</sub></i>) / (<i>S</i><sub>0</sub> <i>S</i><sub>1</sub>)] error.</li></ul> <div class="mw-heading mw-heading3"><h3 id="Neural-network_mixing">Neural-network mixing</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=PAQ&action=edit&section=4" title="Edit section: Neural-network mixing"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Beginning with PAQ7, each model outputs a prediction (instead of a pair of counts). These predictions are averaged in the logistic domain: </p> <ul><li><i>x<sub>i</sub></i> = stretch(P<sub><i>i</i></sub>(1)),</li> <li>P(1) = squash(Σ<sub><i>i</i></sub> <i>w<sub>i</sub></i> <i>x<sub>i</sub></i>),</li></ul> <p>where P(1) is the probability that the next bit will be a 1, P<sub><i>i</i></sub>(1) is the probability estimated by the <i>i</i>-th model, and </p> <ul><li>stretch(<i>x</i>) = ln(<i>x</i> / (1 − <i>x</i>)),</li> <li>squash(<i>x</i>) = 1 / (1 + <i>e</i><sup>−<i>x</i></sup>) (inverse of stretch).</li></ul> <p>After each prediction, the model is updated by adjusting the weights to minimize coding cost: </p> <ul><li><i>w<sub>i</sub></i> ← <i>w<sub>i</sub></i> + η <i>x<sub>i</sub></i> (<i>y</i> − P(1)),</li></ul> <p>where η is the <a href="/wiki/Learning_rate" title="Learning rate">learning rate</a> (typically 0.002 to 0.01), <i>y</i> is the predicted bit, and (<i>y</i> − P(1)) is the prediction error. The weight update algorithm differs from <a href="/wiki/Backpropagation" title="Backpropagation">backpropagation</a> in that the terms P(1)P(0) are dropped. This is because the goal of the neural network is to minimize coding cost, not <a href="/wiki/Root_mean_square" title="Root mean square">root mean square</a> error. </p><p>Most versions of PAQ use a small context to select among sets of weights for the neural network. Some versions use multiple networks whose outputs are combined with one more network prior to the SSE stages. Furthermore, for each input prediction there may be several inputs which are <a href="/wiki/Nonlinear" class="mw-redirect" title="Nonlinear">nonlinear</a> functions of P<sub><i>i</i></sub>(1) in addition to stretch(P(1)). </p> <div class="mw-heading mw-heading3"><h3 id="Context_modeling">Context modeling</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=PAQ&action=edit&section=5" title="Edit section: Context modeling"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Each model partitions the known bits of <i>s</i> into a set of contexts and maps each context to a bit history represented by an 8-bit state. In versions through PAQ6, the state represents a pair of counters (<i>n</i><sub>0</sub>, <i>n</i><sub>1</sub>). In PAQ7 and later versions under certain conditions, the state also represents the value of the last bit or the entire sequence. The states are mapped to probabilities using a 256-entry table for each model. After a prediction by the model, the table entry is adjusted slightly (typically by 0.4%) to reduce the prediction error. </p><p>In all PAQ8 versions, the representable states are as follows: </p> <ul><li>The exact bit sequence for up to 4 bits.</li> <li>A pair of counts and an indicator of the most recent bit for sequences of 5 to 15 bits.</li> <li>A pair of counts for sequences of 16 to 41 bits.</li></ul> <p>To keep the number of states to 256, the following limits are placed on the representable counts: (41, 0), (40, 1), (12, 2), (5, 3), (4, 4), (3, 5), (2, 12), (1, 40), (0, 41). If a count exceeds this limit, then the next state is one chosen to have a similar ratio of <i>n</i><sub>0</sub> to <i>n</i><sub>1</sub>. Thus, if the current state is (<i>n</i><sub>0</sub> = 4, <i>n</i><sub>1</sub> = 4, last bit = 0) and a 1 is observed, then the new state is not (<i>n</i><sub>0</sub> = 4, <i>n</i><sub>1</sub> = 5, last bit = 1). Rather, it is (<i>n</i><sub>0</sub> = 3, n<sub>1</sub> = 4, last bit = 1). </p><p>Most context models are implemented as <a href="/wiki/Hash_table" title="Hash table">hash tables</a>. Some small contexts are implemented as direct <a href="/wiki/Lookup_table" title="Lookup table">lookup tables</a>. </p> <div class="mw-heading mw-heading3"><h3 id="Text_preprocessing">Text preprocessing</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=PAQ&action=edit&section=6" title="Edit section: Text preprocessing"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Some versions of PAQ, in particular PAsQDa, PAQAR (both PAQ6 derivatives), and PAQ8HP1 through PAQ8HP8 (PAQ8 derivatives and <a href="/wiki/Hutter_prize" class="mw-redirect" title="Hutter prize">Hutter prize</a> recipients) preprocess text files by looking up words in an external dictionary and replacing them with 1- to 3-byte codes. In addition, uppercase letters are encoded with a special character followed by the lowercase letter. In the PAQ8HP series, the dictionary is organized by grouping syntactically and semantically related words together. This allows models to use just the most significant bits of the dictionary codes as context. </p> <div class="mw-heading mw-heading2"><h2 id="Comparison">Comparison</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=PAQ&action=edit&section=7" title="Edit section: Comparison"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The following table is a sample from the <a rel="nofollow" class="external text" href="http://mattmahoney.net/dc/text.html">Large Text Compression Benchmark</a> by Matt Mahoney that consists of a file consisting of 10<sup>9</sup> bytes (1 <a href="/wiki/Gigabyte" title="Gigabyte">GB</a>, or 0.931 <a href="/wiki/GiB" class="mw-redirect" title="GiB">GiB</a>) of <a href="/wiki/English_Wikipedia" title="English Wikipedia">English Wikipedia</a> text. </p> <table class="wikitable"> <tbody><tr> <th>Program </th> <th>Compressed size (bytes) </th> <th>% of original size </th> <th>Compression time (<a href="/wiki/Nanosecond" title="Nanosecond">ns</a>/<a href="/wiki/Byte" title="Byte">B</a>) </th> <th>Memory (MiB) </th></tr> <tr> <td>nncp v3.2 </td> <td>107,261,318 </td> <td>10.73 </td> <td>241,871 </td> <td>7600 </td></tr> <tr> <td>cmix v20 </td> <td>110,119,440 </td> <td>11.01 </td> <td>621,780 </td> <td>31650 </td></tr> <tr> <td>PAQ8PX_v206fix1 </td> <td>125,099,359 </td> <td>12.51 </td> <td>291,916 </td> <td>28151 </td></tr> <tr> <td><a href="/wiki/Prediction_by_partial_matching#PPMd" title="Prediction by partial matching">PPMd</a> </td> <td>183,976,014 </td> <td>18.4 </td> <td>880 </td> <td>256 </td></tr> <tr> <td><a href="/wiki/Bzip2" title="Bzip2">bzip2</a> </td> <td>254,007,875 </td> <td>25.4 </td> <td>379 </td> <td>8 </td></tr> <tr> <td><a href="/wiki/Infozip" class="mw-redirect" title="Infozip">InfoZIP</a> </td> <td>322,649,703 </td> <td>32.26 </td> <td>104 </td> <td>0.1 </td></tr></tbody></table> <p>See <a href="/wiki/Lossless_compression#Benchmarks" title="Lossless compression">Lossless compression benchmarks</a> for a list of file compression benchmarks. </p> <div class="mw-heading mw-heading2"><h2 id="History">History</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=PAQ&action=edit&section=8" title="Edit section: History"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The following lists the major enhancements to the PAQ algorithm. In addition, there have been a large number of incremental improvements, which are omitted. </p> <ul><li><b>PAQ1</b> was released on January 6, 2002, by Matt Mahoney. It used fixed weights and did not include an analog or sparse model.</li> <li><b>PAQ1SSE/PAQ2</b> was released on May 11, 2003, by Serge Osnach. It significantly improved compression by adding a Secondary Symbol Estimation (SSE) stage between the predictor and encoder. SSE inputs a short context and the current prediction and outputs a new prediction from a table. The table entry is then adjusted to reflect the actual bit value.</li> <li><b>PAQ3N</b>, released October 9, 2003, added a sparse model.</li> <li><b>PAQ4</b>, released November 15, 2003, by Matt Mahoney used adaptive weighting. <b>PAQ5</b> (December 18, 2003) and <b>PAQ6</b> (December 30, 2003) were minor improvements, including a new analog model. At this point, PAQ was competitive with the best PPM compressors and attracted the attention of the data compression community, which resulted in a large number of incremental improvements through April 2004. Berto Destasio tuned the models and adjusted the bit count discounting schedule. Johan de Bock made improvements to the user interface. David A. Scott made improvements to the arithmetic coder. Fabio Buffoni made speed improvements.</li> <li>During the period May 20, 2004, through July 27, 2004, Alexander Ratushnyak released seven versions of <b>PAQAR</b>, which made significant compression improvements by adding many new models, multiple mixers with weights selected by context, adding an SSE stage to each mixer output, and adding a preprocessor to improve the compression of Intel executable files. PAQAR stood as the top-ranked compressor through the end of 2004 but was significantly slower than prior PAQ versions.</li> <li>During the period January 18, 2005, through February 7, 2005, Przemyslaw Skibinski released four versions of <b>PASqDa</b>, based on PAQ6 and PAQAR with the addition of an English dictionary preprocessor. It achieved the top ranking on the Calgary corpus but not on most other benchmarks.</li> <li>A modified version of <b>PAQ6</b> won the <a href="/wiki/Calgary_Challenge" class="mw-redirect" title="Calgary Challenge">Calgary Challenge</a> on January 10, 2004, by Matt Mahoney. This was bettered by ten subsequent versions of PAQAR by Alexander Ratushnyak. The most recent was submitted on June 5, 2006, consisting of compressed data and program source code totaling 589,862 bytes.</li> <li><b>PAQ7</b> was released December 2005 by Matt Mahoney. PAQ7 is a complete rewrite of PAQ6 and variants (PAQAR, PAsQDa). Compression ratio was similar to PAQAR but 3 times faster. However it lacked x86 and a dictionary, so it did not compress Windows executables and English text files as well as PAsQDa. It does include models for color BMP, TIFF and JPEG files, so compresses these files better. The primary difference from PAQ6 is it uses a neural network to combine models rather than a gradient descent mixer. Another feature is PAQ7's ability to compress embedded jpeg and bitmap images in Excel-, Word- and pdf-files.</li> <li><b>PAQ8A</b> was released on January 27, 2006, <b>PAQ8C</b> on February 13, 2006. These were experimental pre-release of anticipated PAQ8. It fixed several issues in PAQ7 (poor compression in some cases). PAQ8A also included model for compressing (x86) executables.</li> <li><b>PAQ8F</b> was released on February 28, 2006. PAQ8F had three improvements over PAQ8A: a more memory efficient context model, a new indirect context model to improve compression, and a new user interface to support drag and drop in Windows. It does not use an English dictionary like the PAQ8B/C/D/E variants.</li> <li><b>PAQ8G</b> was released March 3, 2006, by Przemyslaw Skibinski. PAQ8G is PAQ8F with dictionaries added and some other improvements as a redesigned TextFilter (which does not decrease compression performance on non-textual files)</li> <li><b>PAQ8H</b> was released on March 22, 2006, by Alexander Ratushnyak and updated on March 24, 2006. PAQ8H is based on PAQ8G with some improvements to the model.</li> <li><b>PAQ8I</b> was released on August 18, 2006, by Pavel L. Holoborodko, with bug fixes on August 24, September 4, and September 13. It added a grayscale image model for <a href="/wiki/Portable_bitmap#PGM_example" class="mw-redirect" title="Portable bitmap">PGM</a> files.</li> <li><b>PAQ8J</b> was released on November 13, 2006, by Bill Pettis. It was based on <b>PAQ8F</b> with some text model improvements taken from PAQ8HP5. Thus, it did not include the text dictionaries from <b>PAQ8G</b> or PGM model from <b>PAQ8I</b>.</li> <li>Serge Osnach released a series of modeling improvements: <b>PAQ8JA</b> on November 16, 2006, <b>PAQ8JB</b> on November 21, and <b>PAQ8JC</b> on November 28.</li> <li><b>PAQ8JD</b> was released on December 30, 2006, by Bill Pettis. This version has since been ported to 32 bit <a href="/wiki/Microsoft_Windows" title="Microsoft Windows">Windows</a> for several processors, and 32 and 64 bit <a href="/wiki/Linux" title="Linux">Linux</a>.</li> <li><b>PAQ8K</b> was released on February 13, 2007, by Bill Pettis. It includes additional models for binary files.</li> <li><b>PAQ8L</b> was released on March 8, 2007 by Matt Mahoney. It is based on PAQ8JD and adds a <a href="/wiki/Dynamic_Markov_Compression" class="mw-redirect" title="Dynamic Markov Compression">DMC</a> model.</li> <li><b>PAQ8O</b> was released on August 24, 2007 by Andreas Morphis. Contains improved <a href="/wiki/BMP_file_format" title="BMP file format">BMP</a> and <a href="/wiki/JPEG" title="JPEG">JPEG</a> models over PAQ8L. Can be optionally compiled with <a href="/wiki/SSE2" title="SSE2">SSE2</a> support and for 64-bit Linux. The algorithm has notable performance benefits under 64-bit OS.</li> <li><b>PAQ8P</b> was released on August 25, 2008, by Andreas Morphis. Contains improved BMP model and adds a <a href="/wiki/WAV" title="WAV">WAV</a> model.</li> <li><b>PAQ8PX</b> was released on April 25, 2009, by Jan Ondrus. It contains various improvements like better WAV compression and <a href="/wiki/EXE" class="mw-redirect" title="EXE">EXE</a> compression.</li> <li><b>PAQ8KX</b> was released on July 15, 2009, by Jan Ondrus. It is a combination of PAQ8K with PAQ8PX.</li> <li><b>PAQ8PF</b> was released on September 9, 2009, by LovePimple without source code (which the <a href="/wiki/GPL" class="mw-redirect" title="GPL">GPL</a> license requires). It compresses 7% worse, but is 7 times faster compared to PAQ8PX v66 (measured with 1 MB English text)</li> <li><b>PAQ9A</b> was released on December 31, 2007, by Matt Mahoney. A new experimental version. It does not include models for specific file types, has an LZP preprocessor and supports files over 2 GB.</li> <li><b><a href="/wiki/ZPAQ" title="ZPAQ">ZPAQ</a></b> was released on March 12, 2009, by Matt Mahoney. It uses a new archive format designed so that the current ZPAQ program will be able to decompress archives created by future ZPAQ versions<sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> (the various PAQ variants listed above are not forward compatible in this fashion). It achieves this by specifying the decompression algorithm in a bytecode program that is stored in each created archive file.<sup id="cite_ref-4" class="reference"><a href="#cite_note-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup></li></ul> <div class="mw-heading mw-heading3"><h3 id="Hutter_Prizes">Hutter Prizes</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=PAQ&action=edit&section=9" title="Edit section: Hutter Prizes"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The series <b>PAQ8HP1</b> through <b>PAQ8HP8</b> were released by Alexander Ratushnyak from August 21, 2006, through January 18, 2007, as <a href="/wiki/Hutter_Prize" title="Hutter Prize">Hutter Prize</a> submissions. The Hutter Prize is a text compression contest using a 100 MB English and XML data set derived from Wikipedia's source. The PAQ8HP series was forked from PAQ8H. The programs include text preprocessing dictionaries and models tuned specifically to the benchmark. All non-text models were removed. The dictionaries were organized to group syntactically and semantically related words and to group words by common suffix. The former strategy improves compression because related words (which are likely to appear in similar context) can be modeled on the high order bits of their dictionary codes. The latter strategy makes the dictionary easier to compress. The size of the decompression program and compressed dictionary is included in the contest ranking. </p><p>On October 27, 2006, it was announced<sup id="cite_ref-5" class="reference"><a href="#cite_note-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> that <b>PAQ8HP5</b> won a <a href="/wiki/Hutter_Prize" title="Hutter Prize">Hutter Prize for Lossless Compression of Human Knowledge</a> of <a href="/wiki/Euro" title="Euro">€</a>3,416. </p><p>On June 30, 2007, Ratushnyak's <b>PAQ8HP12</b> was awarded a second Hutter prize of €1732,<sup id="cite_ref-6" class="reference"><a href="#cite_note-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> improving upon his previous record by 3.46%. </p> <div class="mw-heading mw-heading2"><h2 id="PAQ_derivations">PAQ derivations</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=PAQ&action=edit&section=10" title="Edit section: PAQ derivations"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Being <a href="/wiki/Free_software" title="Free software">free software</a>, PAQ can be modified and redistributed by anyone who has a copy. This has allowed other authors to <a href="/wiki/Fork_(software_development)" title="Fork (software development)">fork</a> the PAQ compression engine and add new features such as a <a href="/wiki/Graphical_user_interface" title="Graphical user interface">graphical user interface</a> or better speed (at the expense of compression ratio). Notable PAQ derivatives include: </p> <ul><li><b>WinUDA 0.291</b>, based on PAQ6 but faster<sup id="cite_ref-mycomp.htm_7-0" class="reference"><a href="#cite_note-mycomp.htm-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup></li> <li><b>UDA 0.301</b>, based on PAQ8I algorithm<sup id="cite_ref-mycomp.htm_7-1" class="reference"><a href="#cite_note-mycomp.htm-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup></li> <li><b><a href="/wiki/KGB_Archiver" title="KGB Archiver">KGB</a></b>, based on PAQ6<sup id="cite_ref-8" class="reference"><a href="#cite_note-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> (beta version is based on PAQ7).</li> <li><b>Emilcont</b> based on PAQ6<sup id="cite_ref-9" class="reference"><a href="#cite_note-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup></li> <li><b><a href="/wiki/Peazip" class="mw-redirect" title="Peazip">Peazip</a></b> GUI frontend (for Windows and Linux) for <abbr title=""Lite" PAQ, single file compressor">LPAQ</abbr>,<sup id="cite_ref-10" class="reference"><a href="#cite_note-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup> ZPAQ and various PAQ8* algorithms<sup id="cite_ref-11" class="reference"><a href="#cite_note-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup></li> <li>PWCM (PAQ weighted context mixing) is an independently developed closed source implementation of the PAQ algorithm used in WinRK.<sup id="cite_ref-12" class="reference"><a href="#cite_note-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup></li> <li><b>PAQCompress</b> is a graphical user interface for several newer PAQ versions, including the latest releases of PAQ8PX, PAQ8PXD and PAQ8PXV. It is updated whenever a new version is released. The software intelligently appends an extension to the filename which it can use to decompress the file using the correct PAQ Version. The software is open source.<sup id="cite_ref-13" class="reference"><a href="#cite_note-13"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup></li> <li><b>PerfectCompress<sup id="cite_ref-14" class="reference"><a href="#cite_note-14"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup></b> Is a compression software which features UCA (ULTRA Compressed Archive). A compression format that featured PAQ8PX v42 to v65 and that now can use PAQ8PF, PAQ8KX, or PAQ8PXPRE as the default UCA Compressor. In addition, PerfectCompress can compress files to PAQ8PX v42 to v67, and ZPAQ, and as of version 6.0, can compress files to LPAQ and PAQ8PF beta 1 to beta 3. PerfectCompress v6.10 introduced support compression for the recently released PAQ8PXPRE. PerfectCompress 6.12 introduces support for the PAQ8KX series.<sup id="cite_ref-15" class="reference"><a href="#cite_note-15"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup></li> <li><b>FrontPAQ</b>, small gui for PAQ. Latest version is FrontPAQ v8 supporting PAQ8PX, PAQ8PF, and FP8. The software is no longer updated and users are encouraged to use PAQCompress, which implements the latest PAQ releases.<sup id="cite_ref-16" class="reference"><a href="#cite_note-16"><span class="cite-bracket">[</span>16<span class="cite-bracket">]</span></a></sup></li></ul> <div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=PAQ&action=edit&section=11" title="Edit section: See also"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1259569809">.mw-parser-output .portalbox{padding:0;margin:0.5em 0;display:table;box-sizing:border-box;max-width:175px;list-style:none}.mw-parser-output .portalborder{border:1px solid var(--border-color-base,#a2a9b1);padding:0.1em;background:var(--background-color-neutral-subtle,#f8f9fa)}.mw-parser-output .portalbox-entry{display:table-row;font-size:85%;line-height:110%;height:1.9em;font-style:italic;font-weight:bold}.mw-parser-output .portalbox-image{display:table-cell;padding:0.2em;vertical-align:middle;text-align:center}.mw-parser-output .portalbox-link{display:table-cell;padding:0.2em 0.2em 0.2em 0.3em;vertical-align:middle}@media(min-width:720px){.mw-parser-output .portalleft{clear:left;float:left;margin:0.5em 1em 0.5em 0}.mw-parser-output .portalright{clear:right;float:right;margin:0.5em 0 0.5em 1em}}</style><ul role="navigation" aria-label="Portals" class="noprint portalbox portalborder portalright"> <li class="portalbox-entry"><span class="portalbox-image"><span class="noviewer" typeof="mw:File"><span><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/3/31/Free_and_open-source_software_logo_%282009%29.svg/28px-Free_and_open-source_software_logo_%282009%29.svg.png" decoding="async" width="28" height="28" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/3/31/Free_and_open-source_software_logo_%282009%29.svg/42px-Free_and_open-source_software_logo_%282009%29.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/3/31/Free_and_open-source_software_logo_%282009%29.svg/56px-Free_and_open-source_software_logo_%282009%29.svg.png 2x" data-file-width="512" data-file-height="512" /></span></span></span><span class="portalbox-link"><a href="/wiki/Portal:Free_and_open-source_software" title="Portal:Free and open-source software">Free and open-source software portal</a></span></li></ul> <ul><li><a href="/wiki/List_of_archive_formats" title="List of archive formats">List of archive formats</a></li> <li><a href="/wiki/Comparison_of_file_archivers" title="Comparison of file archivers">Comparison of file archivers</a></li></ul> <div class="mw-heading mw-heading2"><h2 id="References">References</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=PAQ&action=edit&section=12" title="Edit section: References"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}</style><div class="reflist reflist-columns references-column-width" style="column-width: 30em;"> <ol class="references"> <li id="cite_note-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-1">^</a></b></span> <span class="reference-text"><style data-mw-deduplicate="TemplateStyles:r1238218222">.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/d/d6/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/a/aa/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/4/4c/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}</style><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://mailcom.com/challenge/">"The Compression/SHA-1 Challenge"</a>. Mailcom.com<span class="reference-accessdate">. Retrieved <span class="nowrap">2010-05-19</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=The+Compression%2FSHA-1+Challenge&rft.pub=Mailcom.com&rft_id=http%3A%2F%2Fmailcom.com%2Fchallenge%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3APAQ" class="Z3988"></span></span> </li> <li id="cite_note-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-2">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://mattmahoney.net/dc/">"Homepage of the PAQ compressors"</a><span class="reference-accessdate">. Retrieved <span class="nowrap">2007-07-10</span></span>. <q>You may download, use, copy, modify, and distribute these programs under the terms of the GNU general public license</q></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Homepage+of+the+PAQ+compressors&rft_id=http%3A%2F%2Fmattmahoney.net%2Fdc%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3APAQ" class="Z3988"></span></span> </li> <li id="cite_note-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-3">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://manpages.ubuntu.com/manpages/xenial/en/man1/zpaq.1.html">"Ubuntu Manpage: zpaq - PAQ open standard maximum compressor"</a>. <i>manpages.ubuntu.com</i>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=manpages.ubuntu.com&rft.atitle=Ubuntu+Manpage%3A+zpaq+-+PAQ+open+standard+maximum+compressor&rft_id=https%3A%2F%2Fmanpages.ubuntu.com%2Fmanpages%2Fxenial%2Fen%2Fman1%2Fzpaq.1.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3APAQ" class="Z3988"></span></span> </li> <li id="cite_note-4"><span class="mw-cite-backlink"><b><a href="#cite_ref-4">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://mattmahoney.net/dc/zpaq1.pdf">"ZPAQ Level 1 Specification"</a> <span class="cs1-format">(PDF)</span><span class="reference-accessdate">. Retrieved <span class="nowrap">2010-09-03</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=ZPAQ+Level+1+Specification&rft_id=http%3A%2F%2Fmattmahoney.net%2Fdc%2Fzpaq1.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3APAQ" class="Z3988"></span></span> </li> <li id="cite_note-5"><span class="mw-cite-backlink"><b><a href="#cite_ref-5">^</a></b></span> <span class="reference-text">James Bowery. <a rel="nofollow" class="external text" href="https://groups.google.com/group/Hutter-Prize/browse_frm/thread/3f3f80c76dd14513/">Alexander Ratushnyak Wins First Hutter Prize Payout</a>. Published October 27, 2006. Retrieved October 30, 2006. <sup class="noprint Inline-Template"><span style="white-space: nowrap;">[<i><a href="/wiki/Wikipedia:Link_rot" title="Wikipedia:Link rot"><span title=" Dead link tagged June 2016">dead link</span></a></i><span style="visibility:hidden; color:transparent; padding-left:2px">‍</span>]</span></sup></span> </li> <li id="cite_note-6"><span class="mw-cite-backlink"><b><a href="#cite_ref-6">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external free" href="http://prize.hutter1.net/award2.gif">http://prize.hutter1.net/award2.gif</a> <sup class="noprint Inline-Template" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Bare_URLs" title="Wikipedia:Bare URLs"><span title="A full citation of this image file is required to prevent link rot. (March 2022)">bare URL image file</span></a></i>]</sup></span> </li> <li id="cite_note-mycomp.htm-7"><span class="mw-cite-backlink">^ <a href="#cite_ref-mycomp.htm_7-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-mycomp.htm_7-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://wex.cn/dwing/mycomp.htm">dwing's homepage</a> <a rel="nofollow" class="external text" href="https://web.archive.org/web/20070224151023/http://wex.cn/dwing/mycomp.htm">Archived</a> February 24, 2007, at the <a href="/wiki/Wayback_Machine" title="Wayback Machine">Wayback Machine</a></span> </li> <li id="cite_note-8"><span class="mw-cite-backlink"><b><a href="#cite_ref-8">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20090105160545/http://kgbarchiver.net/">"KGB Archiver homepage"</a>. Kgbarchiver.net. Archived from <a rel="nofollow" class="external text" href="http://kgbarchiver.net/">the original</a> on 2009-01-05<span class="reference-accessdate">. Retrieved <span class="nowrap">2010-05-19</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=KGB+Archiver+homepage&rft.pub=Kgbarchiver.net&rft_id=http%3A%2F%2Fkgbarchiver.net%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3APAQ" class="Z3988"></span></span> </li> <li id="cite_note-9"><span class="mw-cite-backlink"><b><a href="#cite_ref-9">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20100910070903/http://www.freewebs.com/emilcont/">"EmilCont Ultracompression"</a>. Freewebs.com. Archived from <a rel="nofollow" class="external text" href="http://www.freewebs.com/emilcont/">the original</a> on 2010-09-10<span class="reference-accessdate">. Retrieved <span class="nowrap">2010-05-19</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=EmilCont+Ultracompression&rft.pub=Freewebs.com&rft_id=http%3A%2F%2Fwww.freewebs.com%2Femilcont%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3APAQ" class="Z3988"></span></span> </li> <li id="cite_note-10"><span class="mw-cite-backlink"><b><a href="#cite_ref-10">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFMatt_Mahoney2007" class="citation web cs1">Matt Mahoney (2007). <a rel="nofollow" class="external text" href="http://mattmahoney.net/dc/#lpaq">"LPAQ"</a><span class="reference-accessdate">. Retrieved <span class="nowrap">2013-12-29</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=LPAQ&rft.date=2007&rft.au=Matt+Mahoney&rft_id=http%3A%2F%2Fmattmahoney.net%2Fdc%2F%23lpaq&rfr_id=info%3Asid%2Fen.wikipedia.org%3APAQ" class="Z3988"></span></span> </li> <li id="cite_note-11"><span class="mw-cite-backlink"><b><a href="#cite_ref-11">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://peazip.sourceforge.net/peazip-free-archiver.html">"PeaZip"</a>. PeaZip<span class="reference-accessdate">. Retrieved <span class="nowrap">2013-10-06</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=PeaZip&rft.pub=PeaZip&rft_id=http%3A%2F%2Fpeazip.sourceforge.net%2Fpeazip-free-archiver.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3APAQ" class="Z3988"></span></span> </li> <li id="cite_note-12"><span class="mw-cite-backlink"><b><a href="#cite_ref-12">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20090417042621/http://www.maximumcompression.com/data/summary_sf.php">"Single file data compression benchmark, sorted on compression ratio"</a>. Maximumcompression.com. 2007-04-14. Archived from <a rel="nofollow" class="external text" href="http://www.maximumcompression.com/data/summary_sf.php">the original</a> on 2009-04-17<span class="reference-accessdate">. Retrieved <span class="nowrap">2010-05-19</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Single+file+data+compression+benchmark%2C+sorted+on+compression+ratio&rft.pub=Maximumcompression.com&rft.date=2007-04-14&rft_id=http%3A%2F%2Fwww.maximumcompression.com%2Fdata%2Fsummary_sf.php&rfr_id=info%3Asid%2Fen.wikipedia.org%3APAQ" class="Z3988"></span></span> </li> <li id="cite_note-13"><span class="mw-cite-backlink"><b><a href="#cite_ref-13">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://moisescardona.me/paqcompress/">"PAQCompress"</a>. <i>Moisés Cardona</i>. 2019-01-10<span class="reference-accessdate">. Retrieved <span class="nowrap">2019-03-05</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Mois%C3%A9s+Cardona&rft.atitle=PAQCompress&rft.date=2019-01-10&rft_id=https%3A%2F%2Fmoisescardona.me%2Fpaqcompress%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3APAQ" class="Z3988"></span></span> </li> <li id="cite_note-14"><span class="mw-cite-backlink"><b><a href="#cite_ref-14">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://moises-studios.com/?q=PerfectCompress">"PerfectCompress Official Website"</a>. Moises-studios.110mb.com. 2010-04-03<span class="reference-accessdate">. Retrieved <span class="nowrap">2010-05-19</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=PerfectCompress+Official+Website&rft.pub=Moises-studios.110mb.com&rft.date=2010-04-03&rft_id=http%3A%2F%2Fmoises-studios.com%2F%3Fq%3DPerfectCompress&rfr_id=info%3Asid%2Fen.wikipedia.org%3APAQ" class="Z3988"></span></span> </li> <li id="cite_note-15"><span class="mw-cite-backlink"><b><a href="#cite_ref-15">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.facebook.com/pages/PerfectCompress/224694115431">"PerfectCompress Official Facebook Page"</a>. Facebook.com<span class="reference-accessdate">. Retrieved <span class="nowrap">2010-05-19</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=PerfectCompress+Official+Facebook+Page&rft.pub=Facebook.com&rft_id=http%3A%2F%2Fwww.facebook.com%2Fpages%2FPerfectCompress%2F224694115431&rfr_id=info%3Asid%2Fen.wikipedia.org%3APAQ" class="Z3988"></span></span> </li> <li id="cite_note-16"><span class="mw-cite-backlink"><b><a href="#cite_ref-16">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://encode.su/threads/453-FrontPAQ-GUI-frontend-for-PAQ8PF-and-PAQ8PX?p=58940&viewfull=1#post58940">"FrontPAQ - GUI frontend for PAQ8PF and PAQ8PX"</a>. <i>encode.su</i><span class="reference-accessdate">. Retrieved <span class="nowrap">2019-07-26</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=encode.su&rft.atitle=FrontPAQ+-+GUI+frontend+for+PAQ8PF+and+PAQ8PX&rft_id=https%3A%2F%2Fencode.su%2Fthreads%2F453-FrontPAQ-GUI-frontend-for-PAQ8PF-and-PAQ8PX%3Fp%3D58940%26viewfull%3D1%23post58940&rfr_id=info%3Asid%2Fen.wikipedia.org%3APAQ" class="Z3988"></span></span> </li> </ol></div> <div class="mw-heading mw-heading2"><h2 id="Further_reading">Further reading</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=PAQ&action=edit&section=13" title="Edit section: Further reading"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li>David Salomon, Giovanni Motta, (with contributions by David Bryant), <i>Handbook of Data Compression</i>, 5th edition, Springer, 2009, <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/1-84882-902-7" title="Special:BookSources/1-84882-902-7">1-84882-902-7</a>, 5.15 PAQ, pp. 314–319</li> <li>Byron Knoll, Nando de Freitas, <a rel="nofollow" class="external text" href="https://arxiv.org/abs/1108.3298"><i>A Machine Learning Perspective on Predictive Coding with PAQ</i></a>, University of British Columbia, Vancouver, Canada, August 17, 2011</li></ul> <div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=PAQ&action=edit&section=14" title="Edit section: External links"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><span class="official-website"><span class="url"><a rel="nofollow" class="external text" href="http://mattmahoney.net/dc/">Official website</a></span></span></li> <li><a rel="nofollow" class="external text" href="https://powerpaq.sourceforge.net/">Compiled linux binaries</a> - Linux command-line executables download.</li></ul> <div class="navbox-styles"><style data-mw-deduplicate="TemplateStyles:r1129693374">.mw-parser-output .hlist dl,.mw-parser-output .hlist ol,.mw-parser-output .hlist ul{margin:0;padding:0}.mw-parser-output .hlist dd,.mw-parser-output .hlist dt,.mw-parser-output .hlist li{margin:0;display:inline}.mw-parser-output .hlist.inline,.mw-parser-output .hlist.inline dl,.mw-parser-output .hlist.inline ol,.mw-parser-output .hlist.inline ul,.mw-parser-output .hlist dl dl,.mw-parser-output .hlist dl ol,.mw-parser-output .hlist dl ul,.mw-parser-output .hlist ol dl,.mw-parser-output .hlist ol ol,.mw-parser-output .hlist ol ul,.mw-parser-output .hlist ul dl,.mw-parser-output .hlist ul ol,.mw-parser-output .hlist ul ul{display:inline}.mw-parser-output .hlist .mw-empty-li{display:none}.mw-parser-output .hlist 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id="Data_compression_software" style="font-size:114%;margin:0 4em"><a href="/wiki/Data_compression" title="Data compression">Data compression</a> software</div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Comparison_of_file_archivers" title="Comparison of file archivers">Archivers</a> with<br /> compression<br /> <span style="font-size:85%;">(<a href="/wiki/Comparison_of_file_archivers" title="Comparison of file archivers">comparison</a>)</span></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:7em"><a href="/wiki/Free_software" title="Free software">Free software</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/7-Zip" title="7-Zip">7-Zip</a></li> <li><a href="/wiki/Ark_(software)" title="Ark (software)">Ark</a></li> <li><a href="/wiki/Haiku_Applications#Expander" class="mw-redirect" title="Haiku Applications">Expander</a></li> <li><a href="/wiki/FreeArc" title="FreeArc">FreeArc</a></li> <li><a href="/wiki/GNOME_Archive_Manager" class="mw-redirect" title="GNOME Archive Manager">GNOME Archive Manager</a></li> <li><a href="/wiki/Info-ZIP" title="Info-ZIP">Info-ZIP</a></li> <li><a href="/wiki/KGB_Archiver" title="KGB Archiver">KGB Archiver</a></li> <li><a class="mw-selflink selflink">PAQ</a></li> <li><a href="/wiki/Pax_(command)" title="Pax (command)">pax</a></li> <li><a href="/wiki/PeaZip" title="PeaZip">PeaZip</a></li> <li><a href="/wiki/XAD_(software)" title="XAD (software)">XAD</a> (decompression only)</li> <li><a href="/wiki/Xarchiver" title="Xarchiver">Xarchiver</a></li> <li><a href="/wiki/Zipeg" title="Zipeg">Zipeg</a></li> <li><a href="/wiki/ZPAQ" title="ZPAQ">ZPAQ</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:7em"><a href="/wiki/Freeware" title="Freeware">Freeware</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Filzip" title="Filzip">Filzip</a></li> <li><a href="/wiki/LHA_(file_format)" title="LHA (file format)">LHA</a></li> <li><a href="/wiki/Lhasa_(computing)" title="Lhasa (computing)">Lhasa</a> (decompression only)</li> <li><a href="/wiki/StuffIt_Expander" title="StuffIt Expander">StuffIt Expander</a> (decompression only)</li> <li><a href="/wiki/The_Unarchiver" title="The Unarchiver">The Unarchiver</a> (decompression only)</li> <li><a href="/wiki/TUGZip" title="TUGZip">TUGZip</a></li> <li><a href="/wiki/ZipGenius" title="ZipGenius">ZipGenius</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:7em"><a href="/wiki/Commercial_software" title="Commercial software">Commercial</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/ARC_(file_format)" title="ARC (file format)">ARC</a></li> <li><a href="/wiki/ALZip" title="ALZip">ALZip</a></li> <li><a href="/wiki/Archive_Utility" class="mw-redirect" title="Archive Utility">Archive Utility</a></li> <li><a href="/wiki/ARJ" title="ARJ">ARJ</a></li> <li><a href="/wiki/BetterZip" title="BetterZip">BetterZip</a></li> <li><a href="/wiki/MacBinary" title="MacBinary">MacBinary</a></li> <li><a href="/wiki/PKZIP" title="PKZIP">PKZIP/SecureZIP</a></li> <li><a href="/wiki/PowerArchiver" title="PowerArchiver">PowerArchiver</a></li> <li><a href="/wiki/StuffIt" title="StuffIt">StuffIt</a></li> <li><a href="/wiki/WinAce" title="WinAce">WinAce</a></li> <li><a href="/wiki/WinRAR" title="WinRAR">WinRAR</a></li> <li><a href="/wiki/WinZip" title="WinZip">WinZip</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Non-archiving<br />compressors</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:7em">Generic</th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Bzip2" title="Bzip2">bzip2</a></li> <li><a href="/wiki/Compress_(software)" title="Compress (software)">compress</a></li> <li><a href="/wiki/Gzip" title="Gzip">gzip</a></li> <li><a href="/wiki/Lzip" title="Lzip">lzip</a></li> <li><a href="/wiki/Lzop" title="Lzop">lzop</a></li> <li><a href="/wiki/Pack_(software)" title="Pack (software)">pack</a></li> <li><a href="/wiki/Rzip" title="Rzip">rzip</a></li> <li><a href="/wiki/Snappy_(compression)" title="Snappy (compression)">Snappy</a></li> <li><a href="/wiki/XZ_Utils" title="XZ Utils">XZ Utils</a></li> <li><a href="/wiki/Zstd" title="Zstd">zstd</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:7em"><a href="/wiki/Executable_compression" title="Executable compression">For code</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"><a href="/wiki/UPX" title="UPX">UPX</a></div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Data_compression#Audio" title="Data compression">Audio<br /> compression</a><br /> <span style="font-size:85%;">(<a href="/wiki/Comparison_of_audio_coding_formats" title="Comparison of audio coding formats">comparison</a>)</span></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:7em;padding-top:5px; padding-bottom:5px"><a href="/wiki/Lossy_compression" title="Lossy compression">Lossy</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Advanced_Audio_Coding" title="Advanced Audio Coding">AAC</a> <ul><li><a href="/wiki/Fraunhofer_FDK_AAC" title="Fraunhofer FDK AAC">Fraunhofer FDK AAC</a></li> <li><a href="/wiki/Nero_AAC_Codec" title="Nero AAC Codec">Nero AAC Codec</a></li> <li><a href="/wiki/FAAC" title="FAAC">FAAC</a></li></ul></li> <li><a href="/wiki/Helix_(multimedia_project)" title="Helix (multimedia project)">Helix DNA Producer</a></li> <li><a href="/wiki/MP3" title="MP3">MP3</a> <ul><li><a href="/wiki/L3enc" title="L3enc">l3enc</a></li> <li><a href="/wiki/LAME" title="LAME">LAME</a></li></ul></li> <li><a href="/wiki/TooLAME" title="TooLAME">TooLAME</a></li> <li><a href="/wiki/Libavcodec" title="Libavcodec">libavcodec</a></li> <li><a href="/wiki/CELT" title="CELT">libcelt</a></li> <li><a href="/wiki/Opus_(audio_format)" title="Opus (audio format)">libopus</a></li> <li><a href="/wiki/Speex" title="Speex">libspeex</a></li> <li><a href="/wiki/Musepack" title="Musepack">Musepack</a></li> <li><a href="/wiki/Vorbis" title="Vorbis">libvorbis</a></li> <li><a href="/wiki/Windows_Media_Encoder" title="Windows Media Encoder">Windows Media Encoder</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:7em;padding-top:5px; padding-bottom:5px"><a href="/wiki/Lossless_compression" title="Lossless compression">Lossless</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Apple_Lossless_Audio_Codec" title="Apple Lossless Audio Codec">ALAC</a></li> <li><a href="/wiki/FLAC" title="FLAC">FLAC</a></li> <li><a href="/wiki/Libavcodec" title="Libavcodec">libavcodec</a></li> <li><a href="/wiki/Monkey%27s_Audio" title="Monkey's Audio">Monkey's Audio</a></li> <li><a href="/wiki/Audio_Lossless_Coding" title="Audio Lossless Coding">mp4als</a></li> <li><a href="/wiki/OptimFROG" title="OptimFROG">OptimFROG</a></li> <li><a href="/wiki/Shorten_(codec)" title="Shorten (codec)">Shorten</a></li> <li><a href="/wiki/WavPack" title="WavPack">WavPack</a></li> <li><a href="/wiki/L2HC" title="L2HC">L2HC</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Data_compression#Video" title="Data compression">Video<br /> compression</a><br /> <span style="font-size:85%;">(<a href="/wiki/Comparison_of_video_codecs" title="Comparison of video codecs">comparison</a>)</span></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:7em"><a href="/wiki/Lossy_compression" title="Lossy compression">Lossy</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/MPEG-4_Part_2" title="MPEG-4 Part 2">MPEG-4 ASP</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/3ivx" title="3ivx">3ivx</a></li> <li><a href="/wiki/DivX" title="DivX">DivX</a></li> <li><a href="/wiki/Nero_Digital" title="Nero Digital">Nero Digital</a></li> <li><a href="/wiki/FFmpeg" title="FFmpeg">FFmpeg</a></li> <li><a href="/wiki/HDX4" title="HDX4">HDX4</a></li> <li><a href="/wiki/Xvid" title="Xvid">Xvid</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Advanced_Video_Coding" title="Advanced Video Coding">H.264</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/CoreAVC" title="CoreAVC">CoreAVC</a></li> <li>Blu-code</li> <li><a href="/wiki/DivX" title="DivX">DivX</a></li> <li><a href="/wiki/FFmpeg" title="FFmpeg">FFmpeg</a></li> <li><a href="/wiki/Nero_Digital" title="Nero Digital">Nero Digital</a></li> <li><a href="/wiki/OpenH264" title="OpenH264">OpenH264</a></li> <li><a href="/wiki/QuickTime" title="QuickTime">QuickTime</a></li> <li><a href="/wiki/X264" title="X264">x264</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/High_Efficiency_Video_Coding" title="High Efficiency Video Coding">HEVC</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/DivX" title="DivX">DivX</a></li> <li><a href="/wiki/X265" title="X265">x265</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Others</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/CineForm" title="CineForm">CineForm</a></li> <li><a href="/wiki/Cinepak" title="Cinepak">Cinepak</a></li> <li><a href="/wiki/Daala" title="Daala">Daala</a></li> <li><a href="/wiki/Avid_DNxHD" title="Avid DNxHD">DNxHD</a></li> <li><a href="/wiki/Helix_(multimedia_project)" title="Helix (multimedia project)">Helix DNA Producer</a></li> <li><a href="/wiki/Indeo" title="Indeo">Indeo</a></li> <li><a href="/wiki/Libavcodec" title="Libavcodec">libavcodec</a></li> <li><a href="/wiki/Dirac_(video_compression_format)" title="Dirac (video compression format)">Schrödinger (Dirac)</a></li> <li><a href="/wiki/Smart_Bitrate_Control" title="Smart Bitrate Control">SBC</a></li> <li><a href="/wiki/Sorenson_codec" class="mw-redirect" title="Sorenson codec">Sorenson</a></li> <li><a href="/wiki/VP7" class="mw-redirect" title="VP7">VP7</a></li> <li><a href="/wiki/Theora" title="Theora">libtheora</a></li> <li><a href="/wiki/Libvpx" title="Libvpx">libvpx</a></li> <li><a href="/wiki/Windows_Media_Encoder" title="Windows Media Encoder">Windows Media Encoder</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:7em"><a href="/wiki/Lossless_compression" title="Lossless compression">Lossless</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/FFV1" title="FFV1">FFV1</a></li> <li><a href="/wiki/Huffyuv" title="Huffyuv">Huffyuv</a></li> <li><a href="/wiki/Lagarith" title="Lagarith">Lagarith</a></li> <li><a href="/wiki/MSU_Lossless_Video_Codec" title="MSU Lossless Video Codec">MSU Lossless</a></li> <li><a href="/wiki/YULS" title="YULS">YULS</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><td class="navbox-abovebelow" colspan="2"><div> <ul><li>See also: <a href="/wiki/Template:Compression_methods" title="Template:Compression methods">compression methods</a> and <a href="/wiki/Template:Compression_formats" title="Template:Compression formats">compression formats</a></li></ul> </div></td></tr></tbody></table></div><div class="navbox-styles"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236075235"></div><div role="navigation" class="navbox" aria-labelledby="Archive_formats" style="padding:3px"><table class="nowraplinks hlist mw-collapsible autocollapse navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239400231"><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Archive_formats" title="Template:Archive formats"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Archive_formats" title="Template talk:Archive formats"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Archive_formats" title="Special:EditPage/Template:Archive formats"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="Archive_formats" style="font-size:114%;margin:0 4em"><a href="/wiki/Archive_format" class="mw-redirect" title="Archive format">Archive formats</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%">Archiving only</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Ar_(Unix)" title="Ar (Unix)">ar</a></li> <li><a href="/wiki/Cpio" title="Cpio">cpio</a></li> <li><a href="/wiki/Shar_(file_format)" title="Shar (file format)">shar</a></li> <li><a href="/wiki/Tar_(computing)" title="Tar (computing)">tar</a></li> <li><a href="/wiki/LBR_(file_format)" title="LBR (file format)">LBR</a></li> <li><a href="/wiki/Doom_modding" title="Doom modding">WAD</a></li> <li><a href="/wiki/WARC_(file_format)" title="WARC (file format)">WARC</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Compression only</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Brotli" title="Brotli">Brotli</a></li> <li><a href="/wiki/Bzip2" title="Bzip2">bzip2</a></li> <li><a href="/wiki/Compress_(software)" title="Compress (software)">compress</a></li> <li><a href="/wiki/Gzip" title="Gzip">gzip</a></li> <li><a href="/wiki/Zopfli" title="Zopfli">Zopfli</a></li> <li><a href="/wiki/Lempel%E2%80%93Ziv%E2%80%93Markov_chain_algorithm" title="Lempel–Ziv–Markov chain algorithm">LZMA</a></li> <li><a href="/wiki/LZ4_(compression_algorithm)" title="LZ4 (compression algorithm)">LZ4</a></li> <li><a href="/wiki/Lzip" title="Lzip">lzip</a></li> <li><a href="/wiki/Lzop" title="Lzop">lzop</a></li> <li><a href="/wiki/SQ_(program)" title="SQ (program)">SQ</a></li> <li><a href="/wiki/XZ_Utils" title="XZ Utils">xz</a></li> <li><a href="/wiki/Zstd" title="Zstd">Zstandard</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Archiving and compression</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/7z" title="7z">7z</a></li> <li><a href="/wiki/ACE_(compressed_file_format)" title="ACE (compressed file format)">ACE</a></li> <li><a href="/wiki/ARC_(file_format)" title="ARC (file format)">ARC</a></li> <li><a href="/wiki/ARJ" title="ARJ">ARJ</a></li> <li><a href="/wiki/B1_(file_format)" title="B1 (file format)">B1</a></li> <li><a href="/wiki/Cabinet_(file_format)" title="Cabinet (file format)">Cabinet</a></li> <li><a href="/wiki/CFS_(file_format)" title="CFS (file format)">cfs</a></li> <li><a href="/wiki/Compact_Pro" title="Compact Pro">cpt</a></li> <li><a href="/wiki/Dar_(disk_archiver)" title="Dar (disk archiver)">dar</a></li> <li>DGCA</li> <li><a href="/wiki/Apple_Disk_Image" title="Apple Disk Image">.dmg</a></li> <li><a href="/wiki/ALZip" title="ALZip">.egg</a></li> <li><a href="/wiki/KGB_Archiver" title="KGB Archiver">kgb</a></li> <li><a href="/wiki/LHA_(file_format)" title="LHA (file format)">LHA</a></li> <li><a href="/wiki/Lrzip" class="mw-redirect" title="Lrzip">lrzip</a></li> <li><a href="/wiki/LZX" title="LZX">LZX</a></li> <li><a href="/wiki/MPQ_(file_format)" class="mw-redirect" title="MPQ (file format)">MPQ</a></li> <li><a href="/wiki/PeaZip#Native_archive_format" title="PeaZip">PEA</a></li> <li><a href="/wiki/RAR_(file_format)" title="RAR (file format)">RAR</a></li> <li><a href="/wiki/Rzip" title="Rzip">rzip</a></li> <li><a href="/wiki/StuffIt" title="StuffIt">sit</a> <ul><li><a href="/wiki/StuffIt" title="StuffIt">sitx</a></li></ul></li> <li>SQX</li> <li><a class="mw-selflink selflink">UDA</a></li> <li><a href="/wiki/Xar_(archiver)" title="Xar (archiver)">Xar</a></li> <li><a href="/wiki/Zoo_(file_format)" title="Zoo (file format)">zoo</a></li> <li><a href="/wiki/ZIP_(file_format)" title="ZIP (file format)">ZIP</a></li> <li><a href="/wiki/ZPAQ" title="ZPAQ">ZPAQ</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Package_format" title="Package format">Software packaging and distribution</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Apk_(file_format)" title="Apk (file format)">apk</a></li> <li><a href="/wiki/App_(file_format)" title="App (file format)">App</a></li> <li><a href="/wiki/APPX" class="mw-redirect" title="APPX">APPX</a></li> <li><a href="/wiki/Deb_(file_format)" title="Deb (file format)">deb</a></li> <li><a href="/wiki/App_(file_format)" title="App (file format)">HAP</a></li> <li><a href="/wiki/.ipa" title=".ipa">ipa</a></li> <li><a href="/wiki/JAR_(file_format)" title="JAR (file format)">JAR</a> <ul><li><a href="/wiki/WAR_(file_format)" title="WAR (file format)">WAR</a></li> <li><a href="/wiki/Java_EE_Connector_Architecture" class="mw-redirect" title="Java EE Connector Architecture">Java RAR</a></li> <li><a href="/wiki/EAR_(file_format)" title="EAR (file format)">EAR</a></li></ul></li> <li><a href="/wiki/Windows_Installer" title="Windows Installer">MSI</a></li> <li><a href="/wiki/App_Installer" title="App Installer">MSIX</a></li> <li><a href="/wiki/Package_(macOS)" title="Package (macOS)">Package (macOS)</a></li> <li><a href="/wiki/RPM_Package_Manager" title="RPM Package Manager">RPM</a></li> <li><a href="/wiki/XAP_(file_format)" title="XAP (file format)">XAP</a></li> <li><a href="/wiki/XAML_Browser_Applications" title="XAML Browser Applications">XBAP</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Document packaging and distribution</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Open_eBook" title="Open eBook">OEB Package Format</a></li> <li><a href="/wiki/EPUB" title="EPUB">OEBPS Container Format</a></li> <li><a href="/wiki/Open_Packaging_Conventions" title="Open Packaging Conventions">Open Packaging Conventions</a></li> <li><a class="mw-selflink selflink">PAQ</a></li></ul> </div></td></tr><tr><td class="navbox-abovebelow" colspan="2"><div> <ul><li><span class="noviewer" typeof="mw:File"><a href="/wiki/File:Symbol_na_class.svg" class="mw-file-description" title="Non-article page"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/6/6a/Symbol_na_class.svg/16px-Symbol_na_class.svg.png" decoding="async" width="16" height="16" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/6/6a/Symbol_na_class.svg/23px-Symbol_na_class.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/6/6a/Symbol_na_class.svg/31px-Symbol_na_class.svg.png 2x" data-file-width="180" data-file-height="185" /></a></span> <a href="/wiki/Comparison_of_archive_formats" class="mw-redirect" title="Comparison of archive formats">Comparison</a></li> <li><span class="noviewer" typeof="mw:File"><span title="List-Class article"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/d/db/Symbol_list_class.svg/16px-Symbol_list_class.svg.png" decoding="async" width="16" height="16" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/d/db/Symbol_list_class.svg/23px-Symbol_list_class.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/d/db/Symbol_list_class.svg/31px-Symbol_list_class.svg.png 2x" data-file-width="180" data-file-height="185" /></span></span> <a href="/wiki/List_of_archive_formats" title="List of archive formats">List</a></li> <li><span class="noviewer" typeof="mw:File"><span title="Category"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/9/96/Symbol_category_class.svg/16px-Symbol_category_class.svg.png" decoding="async" width="16" height="16" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/9/96/Symbol_category_class.svg/23px-Symbol_category_class.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/9/96/Symbol_category_class.svg/31px-Symbol_category_class.svg.png 2x" data-file-width="180" data-file-height="185" /></span></span> <a href="/wiki/Category:Archive_formats" title="Category:Archive formats">Category</a></li></ul> </div></td></tr></tbody></table></div><div class="navbox-styles"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236075235"></div><div role="navigation" class="navbox" aria-labelledby="Data_compression_methods" style="padding:3px"><table class="nowraplinks hlist mw-collapsible autocollapse navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239400231"><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Compression_methods" title="Template:Compression methods"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Compression_methods" title="Template talk:Compression methods"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Compression_methods" title="Special:EditPage/Template:Compression methods"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="Data_compression_methods" style="font-size:114%;margin:0 4em"><a href="/wiki/Data_compression" title="Data compression">Data compression</a> methods</div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Lossless_compression" title="Lossless compression">Lossless</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:7.0em;font-weight:normal;"><a href="/wiki/Entropy_coding" title="Entropy coding">Entropy type</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Adaptive_coding" title="Adaptive coding">Adaptive coding</a></li> <li><a href="/wiki/Arithmetic_coding" title="Arithmetic coding">Arithmetic</a></li> <li><a href="/wiki/Asymmetric_numeral_systems" title="Asymmetric numeral systems">Asymmetric numeral systems</a></li> <li><a href="/wiki/Golomb_coding" title="Golomb coding">Golomb</a></li> <li><a href="/wiki/Huffman_coding" title="Huffman coding">Huffman</a> <ul><li><a href="/wiki/Adaptive_Huffman_coding" title="Adaptive Huffman coding">Adaptive</a></li> <li><a href="/wiki/Canonical_Huffman_code" title="Canonical Huffman code">Canonical</a></li> <li><a href="/wiki/Modified_Huffman_coding" title="Modified Huffman coding">Modified</a></li></ul></li> <li><a href="/wiki/Range_coding" title="Range coding">Range</a></li> <li><a href="/wiki/Shannon_coding" title="Shannon coding">Shannon</a></li> <li><a href="/wiki/Shannon%E2%80%93Fano_coding" title="Shannon–Fano coding">Shannon–Fano</a></li> <li><a href="/wiki/Shannon%E2%80%93Fano%E2%80%93Elias_coding" title="Shannon–Fano–Elias coding">Shannon–Fano–Elias</a></li> <li><a href="/wiki/Tunstall_coding" title="Tunstall coding">Tunstall</a></li> <li><a href="/wiki/Unary_coding" title="Unary coding">Unary</a></li> <li><a href="/wiki/Universal_code_(data_compression)" title="Universal code (data compression)">Universal</a> <ul><li><a href="/wiki/Exponential-Golomb_coding" title="Exponential-Golomb coding">Exp-Golomb</a></li> <li><a href="/wiki/Fibonacci_coding" title="Fibonacci coding">Fibonacci</a></li> <li><a href="/wiki/Elias_gamma_coding" title="Elias gamma coding">Gamma</a></li> <li><a href="/wiki/Levenshtein_coding" title="Levenshtein coding">Levenshtein</a></li></ul></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:7.0em;font-weight:normal;"><a href="/wiki/Dictionary_coder" title="Dictionary coder">Dictionary type</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Byte_pair_encoding" title="Byte pair encoding">Byte pair encoding</a></li> <li><a href="/wiki/LZ77_and_LZ78" title="LZ77 and LZ78">Lempel–Ziv</a> <ul><li><a href="/wiki/842_(compression_algorithm)" title="842 (compression algorithm)">842</a></li> <li><a href="/wiki/LZ4_(compression_algorithm)" title="LZ4 (compression algorithm)">LZ4</a></li> <li><a href="/wiki/LZJB" class="mw-redirect" title="LZJB">LZJB</a></li> <li><a href="/wiki/Lempel%E2%80%93Ziv%E2%80%93Oberhumer" title="Lempel–Ziv–Oberhumer">LZO</a></li> <li><a href="/wiki/LZRW" title="LZRW">LZRW</a></li> <li><a href="/wiki/Lempel%E2%80%93Ziv%E2%80%93Storer%E2%80%93Szymanski" title="Lempel–Ziv–Storer–Szymanski">LZSS</a></li> <li><a href="/wiki/Lempel%E2%80%93Ziv%E2%80%93Welch" title="Lempel–Ziv–Welch">LZW</a></li> <li><a href="/wiki/LZWL" title="LZWL">LZWL</a></li> <li><a href="/wiki/Snappy_(compression)" title="Snappy (compression)">Snappy</a></li></ul></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:7.0em;font-weight:normal;">Other types</th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Burrows%E2%80%93Wheeler_transform" title="Burrows–Wheeler transform">BWT</a></li> <li><a href="/wiki/Context_tree_weighting" title="Context tree weighting">CTW</a></li> <li><a href="/wiki/Context_mixing" title="Context mixing">CM</a></li> <li><a href="/wiki/Delta_encoding" title="Delta encoding">Delta</a> <ul><li><a href="/wiki/Incremental_encoding" title="Incremental encoding">Incremental</a></li></ul></li> <li><a href="/wiki/Dynamic_Markov_compression" title="Dynamic Markov compression">DMC</a></li> <li><a href="/wiki/Differential_pulse-code_modulation" title="Differential pulse-code modulation">DPCM</a></li> <li><a href="/wiki/Grammar-based_code" title="Grammar-based code">Grammar</a> <ul><li><a href="/wiki/Re-Pair" title="Re-Pair">Re-Pair</a></li> <li><a href="/wiki/Sequitur_algorithm" title="Sequitur algorithm">Sequitur</a></li></ul></li> <li><a href="/wiki/Discrete_cosine_transform" title="Discrete cosine transform">LDCT</a></li> <li><a href="/wiki/Move-to-front_transform" title="Move-to-front transform">MTF</a></li> <li><a class="mw-selflink selflink">PAQ</a></li> <li><a href="/wiki/Prediction_by_partial_matching" title="Prediction by partial matching">PPM</a></li> <li><a href="/wiki/Run-length_encoding" title="Run-length encoding">RLE</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:7.0em;font-weight:normal;">Hybrid</th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li>LZ77 + Huffman <ul><li><a href="/wiki/Deflate" title="Deflate">Deflate</a></li> <li><a href="/wiki/LZX" title="LZX">LZX</a></li> <li><a href="/wiki/Lempel%E2%80%93Ziv%E2%80%93Stac" title="Lempel–Ziv–Stac">LZS</a></li></ul></li> <li>LZ77 + ANS <ul><li><a href="/wiki/LZFSE" title="LZFSE">LZFSE</a></li></ul></li> <li>LZ77 + Huffman + ANS <ul><li><a href="/wiki/Zstd" title="Zstd">Zstandard</a></li></ul></li> <li>LZ77 + Huffman + context <ul><li><a href="/wiki/Brotli" title="Brotli">Brotli</a></li></ul></li> <li>LZSS + Huffman <ul><li><a href="/wiki/LHA_(file_format)" title="LHA (file format)">LHA/LZH</a></li></ul></li> <li>LZ77 + Range <ul><li><a href="/wiki/Lempel%E2%80%93Ziv%E2%80%93Markov_chain_algorithm" title="Lempel–Ziv–Markov chain algorithm">LZMA</a></li> <li>LZHAM</li></ul></li> <li>RLE + BWT + MTF + Huffman <ul><li><a href="/wiki/Bzip2" title="Bzip2">bzip2</a></li></ul></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Lossy_compression" title="Lossy compression">Lossy</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:7.0em;font-weight:normal;"><a href="/wiki/Transform_coding" title="Transform coding">Transform type</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Discrete_cosine_transform" title="Discrete cosine transform">Discrete cosine transform</a> <ul><li><a href="/wiki/Discrete_cosine_transform" title="Discrete cosine transform">DCT</a></li> <li><a href="/wiki/Modified_discrete_cosine_transform" title="Modified discrete cosine transform">MDCT</a></li></ul></li> <li><a href="/wiki/Discrete_sine_transform" title="Discrete sine transform">DST</a></li> <li><a href="/wiki/Fast_Fourier_transform" title="Fast Fourier transform">FFT</a></li> <li><a href="/wiki/Wavelet_transform" title="Wavelet transform">Wavelet</a> <ul><li><a href="/wiki/Daubechies_wavelet" title="Daubechies wavelet">Daubechies</a></li> <li><a href="/wiki/Discrete_wavelet_transform" title="Discrete wavelet transform">DWT</a></li> <li><a href="/wiki/Set_partitioning_in_hierarchical_trees" title="Set partitioning in hierarchical trees">SPIHT</a></li></ul></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:7.0em;font-weight:normal;">Predictive type</th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Differential_pulse-code_modulation" title="Differential pulse-code modulation">DPCM</a> <ul><li><a href="/wiki/Adaptive_differential_pulse-code_modulation" title="Adaptive differential pulse-code modulation">ADPCM</a></li></ul></li> <li><a href="/wiki/Linear_predictive_coding" title="Linear predictive coding">LPC</a> <ul><li><a href="/wiki/Algebraic_code-excited_linear_prediction" title="Algebraic code-excited linear prediction">ACELP</a></li> <li><a href="/wiki/Code-excited_linear_prediction" title="Code-excited linear prediction">CELP</a></li> <li><a href="/wiki/Log_area_ratio" title="Log area ratio">LAR</a></li> <li><a href="/wiki/Line_spectral_pairs" title="Line spectral pairs">LSP</a></li> <li><a href="/wiki/Warped_linear_predictive_coding" title="Warped linear predictive coding">WLPC</a></li></ul></li> <li>Motion <ul><li><a href="/wiki/Motion_compensation" title="Motion compensation">Compensation</a></li> <li><a href="/wiki/Motion_estimation" title="Motion estimation">Estimation</a></li> <li><a href="/wiki/Motion_vector" class="mw-redirect" title="Motion vector">Vector</a></li></ul></li> <li><a href="/wiki/Psychoacoustics" title="Psychoacoustics">Psychoacoustic</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Data_compression#Audio" title="Data compression">Audio</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:7.0em;font-weight:normal;">Concepts</th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Bit_rate" title="Bit rate">Bit rate</a> <ul><li><a href="/wiki/Average_bitrate" title="Average bitrate">ABR</a></li> <li><a href="/wiki/Constant_bitrate" title="Constant bitrate">CBR</a></li> <li><a href="/wiki/Variable_bitrate" title="Variable bitrate">VBR</a></li></ul></li> <li><a href="/wiki/Companding" title="Companding">Companding</a></li> <li><a href="/wiki/Convolution" title="Convolution">Convolution</a></li> <li><a href="/wiki/Dynamic_range" title="Dynamic range">Dynamic range</a></li> <li><a href="/wiki/Latency_(audio)" title="Latency (audio)">Latency</a></li> <li><a href="/wiki/Nyquist%E2%80%93Shannon_sampling_theorem" title="Nyquist–Shannon sampling theorem">Nyquist–Shannon theorem</a></li> <li><a href="/wiki/Sampling_(signal_processing)" title="Sampling (signal processing)">Sampling</a></li> <li><a href="/wiki/Silence_compression" title="Silence compression">Silence compression</a></li> <li><a href="/wiki/Sound_quality" title="Sound quality">Sound quality</a></li> <li><a href="/wiki/Speech_coding" title="Speech coding">Speech coding</a></li> <li><a href="/wiki/Sub-band_coding" title="Sub-band coding">Sub-band coding</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:7.0em;font-weight:normal;"><a href="/wiki/Audio_codec" title="Audio codec">Codec</a> parts</th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/A-law_algorithm" title="A-law algorithm">A-law</a></li> <li><a href="/wiki/%CE%9C-law_algorithm" title="Μ-law algorithm">μ-law</a></li> <li><a href="/wiki/Differential_pulse-code_modulation" title="Differential pulse-code modulation">DPCM</a> <ul><li><a href="/wiki/Adaptive_differential_pulse-code_modulation" title="Adaptive differential pulse-code modulation">ADPCM</a></li> <li><a href="/wiki/Delta_modulation" title="Delta modulation">DM</a></li></ul></li> <li><a href="/wiki/Fourier_transform" title="Fourier transform">FT</a> <ul><li><a href="/wiki/Fast_Fourier_transform" title="Fast Fourier transform">FFT</a></li></ul></li> <li><a href="/wiki/Linear_predictive_coding" title="Linear predictive coding">LPC</a> <ul><li><a href="/wiki/Algebraic_code-excited_linear_prediction" title="Algebraic code-excited linear prediction">ACELP</a></li> <li><a href="/wiki/Code-excited_linear_prediction" title="Code-excited linear prediction">CELP</a></li> <li><a href="/wiki/Log_area_ratio" title="Log area ratio">LAR</a></li> <li><a href="/wiki/Line_spectral_pairs" title="Line spectral pairs">LSP</a></li> <li><a href="/wiki/Warped_linear_predictive_coding" title="Warped linear predictive coding">WLPC</a></li></ul></li> <li><a href="/wiki/Modified_discrete_cosine_transform" title="Modified discrete cosine transform">MDCT</a></li> <li><a href="/wiki/Psychoacoustics" title="Psychoacoustics">Psychoacoustic model</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Image_compression" title="Image compression">Image</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:7.0em;font-weight:normal;">Concepts</th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Chroma_subsampling" title="Chroma subsampling">Chroma subsampling</a></li> <li><a href="/wiki/Coding_tree_unit" title="Coding tree unit">Coding tree unit</a></li> <li><a href="/wiki/Color_space" title="Color space">Color space</a></li> <li><a href="/wiki/Compression_artifact" title="Compression artifact">Compression artifact</a></li> <li><a href="/wiki/Image_resolution" title="Image resolution">Image resolution</a></li> <li><a href="/wiki/Macroblock" title="Macroblock">Macroblock</a></li> <li><a href="/wiki/Pixel" title="Pixel">Pixel</a></li> <li><a href="/wiki/Peak_signal-to-noise_ratio" title="Peak signal-to-noise ratio">PSNR</a></li> <li><a href="/wiki/Quantization_(image_processing)" title="Quantization (image processing)">Quantization</a></li> <li><a href="/wiki/Standard_test_image" title="Standard test image">Standard test image</a></li> <li><a href="/wiki/Texture_compression" title="Texture compression">Texture compression</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:7.0em;font-weight:normal;">Methods</th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Chain_code" title="Chain code">Chain code</a></li> <li><a href="/wiki/Discrete_cosine_transform" title="Discrete cosine transform">DCT</a></li> <li><a href="/wiki/Deflate" title="Deflate">Deflate</a></li> <li><a href="/wiki/Fractal_compression" title="Fractal compression">Fractal</a></li> <li><a href="/wiki/Karhunen%E2%80%93Lo%C3%A8ve_theorem" class="mw-redirect" title="Karhunen–Loève theorem">KLT</a></li> <li><a href="/wiki/Pyramid_(image_processing)" title="Pyramid (image processing)">LP</a></li> <li><a href="/wiki/Run-length_encoding" title="Run-length encoding">RLE</a></li> <li><a href="/wiki/Wavelet_transform" title="Wavelet transform">Wavelet</a> <ul><li><a href="/wiki/Daubechies_wavelet" title="Daubechies wavelet">Daubechies</a></li> <li><a href="/wiki/Discrete_wavelet_transform" title="Discrete wavelet transform">DWT</a></li> <li><a href="/wiki/Embedded_zerotrees_of_wavelet_transforms" title="Embedded zerotrees of wavelet transforms">EZW</a></li> <li><a href="/wiki/Set_partitioning_in_hierarchical_trees" title="Set partitioning in hierarchical trees">SPIHT</a></li></ul></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Data_compression#Video" title="Data compression">Video</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:7.0em;font-weight:normal;">Concepts</th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Bit_rate" title="Bit rate">Bit rate</a> <ul><li><a href="/wiki/Average_bitrate" title="Average bitrate">ABR</a></li> <li><a href="/wiki/Constant_bitrate" title="Constant bitrate">CBR</a></li> <li><a href="/wiki/Variable_bitrate" title="Variable bitrate">VBR</a></li></ul></li> <li><a href="/wiki/Display_resolution" title="Display resolution">Display resolution</a></li> <li><a href="/wiki/Film_frame" title="Film frame">Frame</a></li> <li><a href="/wiki/Frame_rate" title="Frame rate">Frame rate</a></li> <li><a href="/wiki/Video_compression_picture_types" title="Video compression picture types">Frame types</a></li> <li><a href="/wiki/Interlaced_video" title="Interlaced video">Interlace</a></li> <li><a href="/wiki/Video#Characteristics_of_video_streams" title="Video">Video characteristics</a></li> <li><a href="/wiki/Video_quality" title="Video quality">Video quality</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:7.0em;font-weight:normal;"><a href="/wiki/Video_codec" title="Video codec">Codec</a> parts</th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Discrete_cosine_transform" title="Discrete cosine transform">DCT</a></li> <li><a href="/wiki/Differential_pulse-code_modulation" title="Differential pulse-code modulation">DPCM</a></li> <li><a href="/wiki/Deblocking_filter" title="Deblocking filter">Deblocking filter</a></li> <li><a href="/wiki/Lapped_transform" title="Lapped transform">Lapped transform</a></li> <li>Motion <ul><li><a href="/wiki/Motion_compensation" title="Motion compensation">Compensation</a></li> <li><a href="/wiki/Motion_estimation" title="Motion estimation">Estimation</a></li> <li><a href="/wiki/Motion_vector" class="mw-redirect" title="Motion vector">Vector</a></li></ul></li> <li><a href="/wiki/Wavelet_transform" title="Wavelet transform">Wavelet</a> <ul><li><a href="/wiki/Daubechies_wavelet" title="Daubechies wavelet">Daubechies</a></li> <li><a href="/wiki/Discrete_wavelet_transform" title="Discrete wavelet transform">DWT</a></li></ul></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Information_theory" title="Information theory">Theory</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Compressed_data_structure" title="Compressed data structure">Compressed data structures</a> <ul><li><a href="/wiki/Compressed_suffix_array" title="Compressed suffix array">Compressed suffix array</a></li> <li><a href="/wiki/FM-index" title="FM-index">FM-index</a></li></ul></li> <li><a href="/wiki/Entropy_(information_theory)" title="Entropy (information theory)">Entropy</a></li> <li><a href="/wiki/Information_theory" title="Information theory">Information theory</a> <ul><li><a href="/wiki/Timeline_of_information_theory" title="Timeline of information theory">Timeline</a></li></ul></li> <li><a href="/wiki/Kolmogorov_complexity" title="Kolmogorov complexity">Kolmogorov complexity</a></li> <li><a href="/wiki/Prefix_code" title="Prefix code">Prefix code</a></li> <li><a href="/wiki/Quantization_(signal_processing)" title="Quantization (signal processing)">Quantization</a></li> <li><a href="/wiki/Rate%E2%80%93distortion_theory" title="Rate–distortion theory">Rate–distortion</a></li> <li><a href="/wiki/Redundancy_(information_theory)" title="Redundancy (information theory)">Redundancy</a></li> <li><a href="/wiki/Data_compression_symmetry" title="Data compression symmetry">Symmetry</a></li> <li><a href="/wiki/Smallest_grammar_problem" title="Smallest grammar problem">Smallest grammar problem</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Community</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Hutter_Prize" title="Hutter Prize">Hutter Prize</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">People</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Mark_Adler" title="Mark Adler">Mark Adler</a></li></ul> </div></td></tr><tr><td class="navbox-abovebelow" 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