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id="firstHeading" class="firstHeading mw-first-heading"><span class="mw-page-title-main">H.261</span></h1> <div id="p-lang-btn" class="vector-dropdown mw-portlet mw-portlet-lang" > <input type="checkbox" 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. Available in 15 languages" > <label id="p-lang-btn-label" for="p-lang-btn-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--action-progressive mw-portlet-lang-heading-15" aria-hidden="true" ><span class="vector-icon mw-ui-icon-language-progressive mw-ui-icon-wikimedia-language-progressive"></span> <span class="vector-dropdown-label-text">15 languages</span> </label> <div class="vector-dropdown-content"> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="interlanguage-link interwiki-ca mw-list-item"><a href="https://ca.wikipedia.org/wiki/H.261" title="H.261 – Catalan" lang="ca" hreflang="ca" data-title="H.261" data-language-autonym="Català" data-language-local-name="Catalan" class="interlanguage-link-target"><span>Català</span></a></li><li class="interlanguage-link interwiki-cs mw-list-item"><a href="https://cs.wikipedia.org/wiki/H.261" title="H.261 – Czech" lang="cs" hreflang="cs" data-title="H.261" data-language-autonym="Čeština" data-language-local-name="Czech" class="interlanguage-link-target"><span>Čeština</span></a></li><li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/H.261" title="H.261 – German" lang="de" hreflang="de" data-title="H.261" data-language-autonym="Deutsch" data-language-local-name="German" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-el mw-list-item"><a href="https://el.wikipedia.org/wiki/%CE%97.261" title="Η.261 – Greek" lang="el" hreflang="el" data-title="Η.261" data-language-autonym="Ελληνικά" data-language-local-name="Greek" class="interlanguage-link-target"><span>Ελληνικά</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/H.261" title="H.261 – Spanish" lang="es" hreflang="es" data-title="H.261" 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/H.261" title="H.261 – French" lang="fr" hreflang="fr" data-title="H.261" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-ko mw-list-item"><a href="https://ko.wikipedia.org/wiki/H.261" title="H.261 – Korean" lang="ko" hreflang="ko" data-title="H.261" data-language-autonym="한국어" data-language-local-name="Korean" class="interlanguage-link-target"><span>한국어</span></a></li><li class="interlanguage-link interwiki-it mw-list-item"><a href="https://it.wikipedia.org/wiki/H.261" title="H.261 – Italian" lang="it" hreflang="it" data-title="H.261" data-language-autonym="Italiano" data-language-local-name="Italian" class="interlanguage-link-target"><span>Italiano</span></a></li><li class="interlanguage-link interwiki-nl mw-list-item"><a href="https://nl.wikipedia.org/wiki/H.261" title="H.261 – Dutch" lang="nl" hreflang="nl" data-title="H.261" data-language-autonym="Nederlands" data-language-local-name="Dutch" class="interlanguage-link-target"><span>Nederlands</span></a></li><li class="interlanguage-link interwiki-ja mw-list-item"><a href="https://ja.wikipedia.org/wiki/H.261" title="H.261 – Japanese" lang="ja" hreflang="ja" data-title="H.261" 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-pl mw-list-item"><a href="https://pl.wikipedia.org/wiki/H.261" title="H.261 – Polish" lang="pl" hreflang="pl" data-title="H.261" data-language-autonym="Polski" data-language-local-name="Polish" class="interlanguage-link-target"><span>Polski</span></a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/H.261" title="H.261 – Russian" lang="ru" hreflang="ru" data-title="H.261" 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/H.261" title="H.261 – Ukrainian" lang="uk" hreflang="uk" data-title="H.261" data-language-autonym="Українська" data-language-local-name="Ukrainian" class="interlanguage-link-target"><span>Українська</span></a></li><li class="interlanguage-link interwiki-yo mw-list-item"><a href="https://yo.wikipedia.org/wiki/H.261" title="H.261 – Yoruba" lang="yo" hreflang="yo" data-title="H.261" data-language-autonym="Yorùbá" data-language-local-name="Yoruba" class="interlanguage-link-target"><span>Yorùbá</span></a></li><li class="interlanguage-link interwiki-zh mw-list-item"><a href="https://zh.wikipedia.org/wiki/H.261" title="H.261 – Chinese" lang="zh" hreflang="zh" data-title="H.261" data-language-autonym="中文" data-language-local-name="Chinese" class="interlanguage-link-target"><span>中文</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/Q1148249#sitelinks-wikipedia" title="Edit interlanguage links" class="wbc-editpage">Edit links</a></span></div> </div> </div> </div> </header> <div class="vector-page-toolbar"> <div class="vector-page-toolbar-container"> <div id="left-navigation"> <nav aria-label="Namespaces"> <div id="p-associated-pages" class="vector-menu vector-menu-tabs mw-portlet mw-portlet-associated-pages" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="ca-nstab-main" class="selected vector-tab-noicon mw-list-item"><a href="/wiki/H.261" title="View the content page [c]" accesskey="c"><span>Article</span></a></li><li id="ca-talk" class="vector-tab-noicon mw-list-item"><a href="/wiki/Talk:H.261" rel="discussion" title="Discuss 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Unsourced material may be challenged and removed.<br /><small><span class="plainlinks"><i>Find sources:</i> <a rel="nofollow" class="external text" href="https://www.google.com/search?as_eq=wikipedia&q=%22H.261%22">"H.261"</a> – <a rel="nofollow" class="external text" href="https://www.google.com/search?tbm=nws&q=%22H.261%22+-wikipedia&tbs=ar:1">news</a> <b>·</b> <a rel="nofollow" class="external text" href="https://www.google.com/search?&q=%22H.261%22&tbs=bkt:s&tbm=bks">newspapers</a> <b>·</b> <a rel="nofollow" class="external text" href="https://www.google.com/search?tbs=bks:1&q=%22H.261%22+-wikipedia">books</a> <b>·</b> <a rel="nofollow" class="external text" href="https://scholar.google.com/scholar?q=%22H.261%22">scholar</a> <b>·</b> <a rel="nofollow" class="external text" href="https://www.jstor.org/action/doBasicSearch?Query=%22H.261%22&acc=on&wc=on">JSTOR</a></span></small></span> <span class="date-container"><i>(<span class="date">May 2023</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> <style data-mw-deduplicate="TemplateStyles:r1257001546">.mw-parser-output .infobox-subbox{padding:0;border:none;margin:-3px;width:auto;min-width:100%;font-size:100%;clear:none;float:none;background-color:transparent}.mw-parser-output .infobox-3cols-child{margin:auto}.mw-parser-output .infobox .navbar{font-size:100%}@media screen{html.skin-theme-clientpref-night .mw-parser-output .infobox-full-data:not(.notheme)>div:not(.notheme)[style]{background:#1f1f23!important;color:#f8f9fa}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .infobox-full-data:not(.notheme) div:not(.notheme){background:#1f1f23!important;color:#f8f9fa}}@media(min-width:640px){body.skin--responsive .mw-parser-output .infobox-table{display:table!important}body.skin--responsive .mw-parser-output .infobox-table>caption{display:table-caption!important}body.skin--responsive .mw-parser-output .infobox-table>tbody{display:table-row-group}body.skin--responsive .mw-parser-output .infobox-table tr{display:table-row!important}body.skin--responsive .mw-parser-output .infobox-table th,body.skin--responsive .mw-parser-output .infobox-table td{padding-left:inherit;padding-right:inherit}}</style><table class="infobox hproduct"><caption class="infobox-title fn">H.261</caption><tbody><tr><td colspan="2" class="infobox-subheader">Video codec for audiovisual services at p x 64 kbit/s</td></tr><tr><th scope="row" class="infobox-label">Status</th><td class="infobox-data">Published</td></tr><tr><th scope="row" class="infobox-label">Year started</th><td class="infobox-data">1988</td></tr><tr><th scope="row" class="infobox-label">Latest version</th><td class="infobox-data">(03/93)</td></tr><tr><th scope="row" class="infobox-label">Organization</th><td class="infobox-data"><a href="/wiki/ITU-T" title="ITU-T">ITU-T</a>, <a href="/wiki/Hitachi" title="Hitachi">Hitachi</a>, <a href="/wiki/PictureTel" title="PictureTel">PictureTel</a>, <a href="/wiki/Nippon_Telegraph_and_Telephone" title="Nippon Telegraph and Telephone">NTT</a>, <a href="/wiki/BT_plc" class="mw-redirect" title="BT plc">BT</a>, <a href="/wiki/Toshiba" title="Toshiba">Toshiba</a>, <a href="#Patent_holders">etc.</a></td></tr><tr><th scope="row" class="infobox-label">Committee</th><td class="infobox-data"><a href="/wiki/ITU-T_Study_Group_16" title="ITU-T Study Group 16">ITU-T Study Group 16</a> <a href="/wiki/VCEG" class="mw-redirect" title="VCEG">VCEG</a> (then: Specialists Group on Coding for Visual Telephony)</td></tr><tr><th scope="row" class="infobox-label">Related standards</th><td class="infobox-data"><a href="/wiki/H.262" class="mw-redirect" title="H.262">H.262</a>, <a href="/wiki/H.263" title="H.263">H.263</a>, <a href="/wiki/H.264" class="mw-redirect" title="H.264">H.264</a>, <a href="/wiki/H.265" class="mw-redirect" title="H.265">H.265</a>, <a href="/wiki/H.266" class="mw-redirect" title="H.266">H.266</a>, <a href="/wiki/H.320" title="H.320">H.320</a>, <a href="/wiki/ISO/IEC_14496-2" class="mw-redirect" title="ISO/IEC 14496-2">ISO/IEC 14496-2</a></td></tr><tr><th scope="row" class="infobox-label">Domain</th><td class="infobox-data"><a href="/wiki/Video_compression" class="mw-redirect" title="Video compression">video compression</a></td></tr><tr><th scope="row" class="infobox-label">Website</th><td class="infobox-data"><a rel="nofollow" class="external free" href="https://www.itu.int/rec/T-REC-H.261">https://www.itu.int/rec/T-REC-H.261</a></td></tr></tbody></table> <p><b>H.261</b> is an <a href="/wiki/ITU-T" title="ITU-T">ITU-T</a> <a href="/wiki/Video_compression_standard" class="mw-redirect" title="Video compression standard">video compression standard</a>, first ratified in November 1988.<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><sup id="cite_ref-H2611988_2-0" class="reference"><a href="#cite_note-H2611988-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> It is the first member of the H.26x family of video coding standards in the domain of the <a href="/wiki/ITU-T_Study_Group_16" title="ITU-T Study Group 16">ITU-T Study Group 16</a> <a href="/wiki/Video_Coding_Experts_Group" title="Video Coding Experts Group">Video Coding Experts Group</a> (<a href="/wiki/VCEG" class="mw-redirect" title="VCEG">VCEG</a>, then Specialists Group on Coding for Visual Telephony). It was the first video coding standard that was useful in practical terms. </p><p>H.261 was originally designed for transmission over <a href="/wiki/Integrated_Services_Digital_Network" class="mw-redirect" title="Integrated Services Digital Network">ISDN</a> lines on which data rates are multiples of 64 kbit/s. The coding algorithm was designed to be able to operate at video bit rates between 40 kbit/s and 2 Mbit/s. The standard supports two video frame sizes: <a href="/wiki/Common_Intermediate_Format" title="Common Intermediate Format">CIF</a> (352×288 luma with 176×144 chroma) and QCIF (176×144 with 88×72 chroma) using a <a href="/wiki/4:2:0" class="mw-redirect" title="4:2:0">4:2:0</a> sampling scheme. It also has a backward-compatible trick for sending still images with 704×576 luma resolution and 352×288 chroma resolution (which was added in a later revision in 1993). </p> <meta property="mw:PageProp/toc" /> <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=H.261&action=edit&section=1" title="Edit section: History"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The first digital <a href="/wiki/Video_coding_standard" class="mw-redirect" title="Video coding standard">video coding standard</a> was <a href="/wiki/H.120" title="H.120">H.120</a>, created by the <a href="/wiki/ITU-T" title="ITU-T">CCITT</a> (now ITU-T) in 1984.<sup id="cite_ref-history_3-0" class="reference"><a href="#cite_note-history-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> H.120 was not usable in practice, as its performance was too poor.<sup id="cite_ref-history_3-1" class="reference"><a href="#cite_note-history-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> H.120 was based on <a href="/wiki/Differential_pulse-code_modulation" title="Differential pulse-code modulation">differential pulse-code modulation</a> (DPCM), which had inefficient compression. During the late 1980s, a number of companies began experimenting with the much more efficient DCT compression for video coding, with the CCITT receiving 14 proposals for DCT-based video compression formats, in contrast to a single proposal based on <a href="/wiki/Vector_quantization" title="Vector quantization">vector quantization</a> (VQ) compression. The H.261 standard was subsequently developed based on DCT compression.<sup id="cite_ref-Ghanbari_4-0" class="reference"><a href="#cite_note-Ghanbari-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> </p><p>H.261 was developed by the <a href="/wiki/CCITT" class="mw-redirect" title="CCITT">CCITT</a> Study Group XV Specialists Group on Coding for Visual Telephony (which later became part of ITU-T SG16), chaired by Sakae Okubo of <a href="/wiki/Nippon_Telegraph_and_Telephone" title="Nippon Telegraph and Telephone">NTT</a>.<sup id="cite_ref-Okubo_5-0" class="reference"><a href="#cite_note-Okubo-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> Since H.261, DCT compression has been adopted by all the major video coding standards that followed.<sup id="cite_ref-Ghanbari_4-1" class="reference"><a href="#cite_note-Ghanbari-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> </p><p>Whilst H.261 was preceded in 1984 by H.120 (which also underwent a revision in 1988 of some historic importance) as a digital video coding standard, H.261 was the first truly practical digital video coding standard (in terms of product support in significant quantities). In fact, all subsequent international video coding standards (<a href="/wiki/MPEG-1#Part_2:_Video" title="MPEG-1">MPEG-1 Part 2</a>, <a href="/wiki/H.262/MPEG-2_Part_2" title="H.262/MPEG-2 Part 2">H.262/MPEG-2 Part 2</a>, <a href="/wiki/H.263" title="H.263">H.263</a>, <a href="/wiki/MPEG-4_Part_2" title="MPEG-4 Part 2">MPEG-4 Part 2</a>, <a href="/wiki/H.264/MPEG-4_AVC" class="mw-redirect" title="H.264/MPEG-4 AVC">H.264/MPEG-4 Part 10</a>, and <a href="/wiki/HEVC" class="mw-redirect" title="HEVC">HEVC</a>) have been based closely on the H.261 design. Additionally, the methods used by the H.261 development committee to collaboratively develop the standard have remained the basic operating process for subsequent standardization work in the field.<sup id="cite_ref-Okubo_5-1" class="reference"><a href="#cite_note-Okubo-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> </p><p>Although H.261 was first approved as a standard in 1988, the first version was missing some significant elements necessary to make it a complete <a href="/wiki/Interoperability" title="Interoperability">interoperability</a> specification. Various parts of it were marked as "Under Study".<sup id="cite_ref-H2611988_2-1" class="reference"><a href="#cite_note-H2611988-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> It was later revised in 1990 to add the remaining necessary aspects,<sup id="cite_ref-H2611990_6-0" class="reference"><a href="#cite_note-H2611990-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> and was then revised again in 1993.<sup id="cite_ref-H2611993_7-0" class="reference"><a href="#cite_note-H2611993-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> The 1993 revision added an Annex D entitled "Still image transmission", which provided a backward-compatible way to send <a href="/wiki/Still_image" class="mw-redirect" title="Still image">still images</a> with 704×576 luma resolution and 352×288 chroma resolution by using a staggered 2:1 <a href="/wiki/Decimation_(signal_processing)" class="mw-redirect" title="Decimation (signal processing)">subsampling</a> horizontally and vertically to separate the picture into four sub-pictures that were sent sequentially.<sup id="cite_ref-H2611993_7-1" class="reference"><a href="#cite_note-H2611993-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="H.261_design">H.261 design</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=H.261&action=edit&section=2" title="Edit section: H.261 design"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The basic processing unit of the design is called a <a href="/wiki/Macroblock" title="Macroblock">macroblock</a>, and H.261 was the first standard in which the macroblock concept appeared. Each macroblock consists of a 16×16 array of <a href="/wiki/Luminance_(video)" class="mw-redirect" title="Luminance (video)">luma</a> samples and two corresponding 8×8 arrays of <a href="/wiki/Chrominance" title="Chrominance">chroma</a> samples, using <a href="/wiki/Chroma_subsampling" title="Chroma subsampling">4:2:0 sampling</a> and a <a href="/wiki/YCbCr" title="YCbCr">YCbCr</a> <a href="/wiki/Color_space" title="Color space">color space</a>. The coding algorithm uses a hybrid of <a href="/wiki/Motion_compensation" title="Motion compensation">motion-compensated</a> <a href="/wiki/Inter_prediction" class="mw-redirect" title="Inter prediction">inter-picture prediction</a> and spatial <a href="/wiki/Transform_coding" title="Transform coding">transform coding</a> with <a href="/wiki/Scalar_quantization" class="mw-redirect" title="Scalar quantization">scalar quantization</a>, zig-zag scanning and <a href="/wiki/Entropy_encoding" class="mw-redirect" title="Entropy encoding">entropy encoding</a>. </p><p>The inter-picture prediction reduces temporal redundancy, with <a href="/wiki/Motion_vector" class="mw-redirect" title="Motion vector">motion vectors</a> used to compensate for motion. Whilst only integer-valued motion vectors are supported in H.261, a blurring filter can be applied to the prediction signal – partially mitigating the lack of fractional-sample motion vector precision. Transform coding using an 8×8 <a href="/wiki/Discrete_cosine_transform" title="Discrete cosine transform">discrete cosine transform</a> (DCT) reduces the spatial redundancy. The DCT that is widely used in this regard was introduced by <a href="/wiki/N._Ahmed" class="mw-redirect" title="N. Ahmed">N. Ahmed</a>, T. Natarajan and <a href="/wiki/K._R._Rao" title="K. R. Rao">K. R. Rao</a> in 1974.<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> Scalar quantization is then applied to round the transform coefficients to the appropriate precision determined by a step size control parameter, and the quantized transform coefficients are zig-zag scanned and entropy-coded (using a "<a href="/wiki/Run-length_encoding" title="Run-length encoding">run</a>-level" <a href="/wiki/Variable-length_code" title="Variable-length code">variable-length code</a>) to remove statistical redundancy. </p><p>The H.261 standard actually only specifies how to decode the video. Encoder designers were left free to design their own encoding algorithms (such as their own <a href="/wiki/Motion_estimation" title="Motion estimation">motion estimation</a> algorithms), as long as their output was constrained properly to allow it to be decoded by any decoder made according to the standard. Encoders are also left free to perform any pre-processing they want to their input video, and decoders are allowed to perform any post-processing they want to their decoded video prior to display. One effective post-processing technique that became a key element of the best H.261-based systems is called <a href="/wiki/Deblocking" class="mw-redirect" title="Deblocking">deblocking</a> filtering. This reduces the appearance of block-shaped artifacts caused by the block-based <a href="/wiki/Motion_compensation" title="Motion compensation">motion compensation</a> and spatial transform parts of the design. Indeed, blocking artifacts are probably a familiar phenomenon to almost everyone who has watched digital video. Deblocking filtering has since become an integral part of the more recent standards <a href="/wiki/H.264" class="mw-redirect" title="H.264">H.264</a> and <a href="/wiki/HEVC" class="mw-redirect" title="HEVC">HEVC</a> (although even when using these newer standards, additional post-processing is still allowed and can enhance visual quality if performed well). </p><p>Design refinements introduced in later standardization efforts have resulted in significant improvements in compression capability relative to the H.261 design. This has resulted in H.261 becoming essentially obsolete, although it is still used as a backward-compatibility mode in some video-conferencing systems (such as <a href="/wiki/H.323" title="H.323">H.323</a>) and for some types of internet video. However, H.261 remains a major historical milestone in the field of video coding development. </p> <div class="mw-heading mw-heading2"><h2 id="Software_implementations">Software implementations</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=H.261&action=edit&section=3" title="Edit section: Software implementations"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The <a href="/wiki/LGPL" class="mw-redirect" title="LGPL">LGPL</a>-licensed <a href="/wiki/Libavcodec" title="Libavcodec">libavcodec</a> includes a H.261 encoder and decoder. It is supported by the free <a href="/wiki/VLC_media_player" title="VLC media player">VLC media player</a> and <a href="/wiki/MPlayer" title="MPlayer">MPlayer</a> multimedia players, and in <a href="/wiki/Ffdshow" title="Ffdshow">ffdshow</a> and <a href="/wiki/FFmpeg" title="FFmpeg">FFmpeg</a> decoders projects. </p> <div class="mw-heading mw-heading2"><h2 id="Patent_holders">Patent holders</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=H.261&action=edit&section=4" title="Edit section: Patent holders"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The following companies contributed <a href="/wiki/Patent" title="Patent">patents</a> towards the development of the H.261 format:<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> </p> <ul><li><a href="/wiki/Hitachi" title="Hitachi">Hitachi</a></li> <li><a href="/wiki/PictureTel_Corp." class="mw-redirect" title="PictureTel Corp.">PictureTel Corp.</a></li> <li>Graphics Communication Technologies, Ltd.<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></li> <li><a href="/wiki/Nippon_Telegraph_and_Telephone" title="Nippon Telegraph and Telephone">Nippon Telegraph and Telephone</a> (NTT)</li> <li><a href="/wiki/BT_Group" title="BT Group">BT Group</a></li> <li><a href="/wiki/Toshiba" title="Toshiba">Toshiba</a></li> <li><a href="/wiki/KDDI" title="KDDI">KDDI</a></li> <li><a href="/wiki/Alcatel-Lucent" title="Alcatel-Lucent">Alcatel</a></li> <li><a href="/wiki/Asure_Software" title="Asure Software">Compression Labs, Inc.</a></li> <li><a href="/wiki/AT%26T_Corporation" title="AT&T Corporation">AT&T Corporation</a></li> <li>GPT Data Systems (<a href="/wiki/General_Electric_Company" title="General Electric Company">GEC</a>)</li> <li><a href="/wiki/Philips" title="Philips">Philips</a></li> <li><a href="/wiki/Sony" title="Sony">Sony</a></li> <li><a href="/wiki/Sharp_Corporation" title="Sharp Corporation">Sharp Corporation</a></li> <li><a href="/wiki/OKI_(conglomerate_company)" class="mw-redirect" title="OKI (conglomerate company)">Oki Electric Industry</a></li> <li><a href="/wiki/Panasonic" title="Panasonic">Matsushita Communication Industrial Co., Ltd.</a></li> <li><a href="/wiki/Mitsubishi_Electric" title="Mitsubishi Electric">Mitsubishi Electric</a></li> <li><a href="/wiki/Fujitsu" title="Fujitsu">Fujitsu</a></li> <li><a href="/wiki/Orange_S.A." class="mw-redirect" title="Orange S.A.">Orange S.A.</a></li> <li><a href="/wiki/NEC" title="NEC">NEC</a></li> <li><a href="/wiki/Electronics_and_Telecommunications_Research_Institute" title="Electronics and Telecommunications Research Institute">Electronics and Telecommunications Research Institute</a></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=H.261&action=edit&section=5" title="Edit section: See also"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/Video_compression" class="mw-redirect" title="Video compression">Video compression</a></li> <li><a href="/wiki/Common_Intermediate_Format" title="Common Intermediate Format">CIF – Common Intermediate Format</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=H.261&action=edit&section=6" 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"> <div class="mw-references-wrap"><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://www.w3.org/2007/08/video/positions/Nokia.pdf">"(Nokia position paper) Web Architecture and Codec Considerations for Audio-Visual Services"</a> <span class="cs1-format">(PDF)</span>. <q>H.261, which (in its first version) was ratified in November 1988.</q></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=%28Nokia+position+paper%29+Web+Architecture+and+Codec+Considerations+for+Audio-Visual+Services&rft_id=http%3A%2F%2Fwww.w3.org%2F2007%2F08%2Fvideo%2Fpositions%2FNokia.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3AH.261" class="Z3988"></span></span> </li> <li id="cite_note-H2611988-2"><span class="mw-cite-backlink">^ <a href="#cite_ref-H2611988_2-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-H2611988_2-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFITU-T1988" class="citation web cs1">ITU-T (1988). <a rel="nofollow" class="external text" href="http://www.itu.int/rec/T-REC-H.261-198811-S/en">"H.261 : Video codec for audiovisual services at p x 384 kbit/s - Recommendation H.261 (11/88)"</a><span class="reference-accessdate">. Retrieved <span class="nowrap">2010-10-21</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=H.261+%3A+Video+codec+for+audiovisual+services+at+p+x+384+kbit%2Fs+-+Recommendation+H.261+%2811%2F88%29&rft.date=1988&rft.au=ITU-T&rft_id=http%3A%2F%2Fwww.itu.int%2Frec%2FT-REC-H.261-198811-S%2Fen&rfr_id=info%3Asid%2Fen.wikipedia.org%3AH.261" class="Z3988"></span></span> </li> <li id="cite_note-history-3"><span class="mw-cite-backlink">^ <a href="#cite_ref-history_3-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-history_3-1"><sup><i><b>b</b></i></sup></a></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://www.real.com/resources/digital-video-file-formats/">"The History of Video File Formats Infographic"</a>. <i><a href="/wiki/RealNetworks" title="RealNetworks">RealNetworks</a></i>. 22 April 2012<span class="reference-accessdate">. Retrieved <span class="nowrap">5 August</span> 2019</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=RealNetworks&rft.atitle=The+History+of+Video+File+Formats+Infographic&rft.date=2012-04-22&rft_id=http%3A%2F%2Fwww.real.com%2Fresources%2Fdigital-video-file-formats%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3AH.261" class="Z3988"></span></span> </li> <li id="cite_note-Ghanbari-4"><span class="mw-cite-backlink">^ <a href="#cite_ref-Ghanbari_4-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Ghanbari_4-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFGhanbari2003" class="citation book cs1">Ghanbari, Mohammed (2003). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=7XuU8T3ooOAC&pg=PA1"><i>Standard Codecs: Image Compression to Advanced Video Coding</i></a>. <a href="/wiki/Institution_of_Engineering_and_Technology" title="Institution of Engineering and Technology">Institution of Engineering and Technology</a>. pp. <span class="nowrap">1–</span>2. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/9780852967102" title="Special:BookSources/9780852967102"><bdi>9780852967102</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Standard+Codecs%3A+Image+Compression+to+Advanced+Video+Coding&rft.pages=%3Cspan+class%3D%22nowrap%22%3E1-%3C%2Fspan%3E2&rft.pub=Institution+of+Engineering+and+Technology&rft.date=2003&rft.isbn=9780852967102&rft.aulast=Ghanbari&rft.aufirst=Mohammed&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3D7XuU8T3ooOAC%26pg%3DPA1&rfr_id=info%3Asid%2Fen.wikipedia.org%3AH.261" class="Z3988"></span></span> </li> <li id="cite_note-Okubo-5"><span class="mw-cite-backlink">^ <a href="#cite_ref-Okubo_5-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Okubo_5-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">S. Okubo, "Reference model methodology – A tool for the collaborative creation of video coding standards", <i>Proceedings of the IEEE</i>, vol. 83, no. 2, Feb. 1995, pp. 139–150</span> </li> <li id="cite_note-H2611990-6"><span class="mw-cite-backlink"><b><a href="#cite_ref-H2611990_6-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFITU-T1990" class="citation web cs1">ITU-T (1990). <a rel="nofollow" class="external text" href="http://www.itu.int/rec/T-REC-H.261-199012-S/en">"H.261 : Video codec for audiovisual services at p x 64 kbit/s - Recommendation H.261 (12/90)"</a><span class="reference-accessdate">. Retrieved <span class="nowrap">2015-12-10</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=H.261+%3A+Video+codec+for+audiovisual+services+at+p+x+64+kbit%2Fs+-+Recommendation+H.261+%2812%2F90%29&rft.date=1990&rft.au=ITU-T&rft_id=http%3A%2F%2Fwww.itu.int%2Frec%2FT-REC-H.261-199012-S%2Fen&rfr_id=info%3Asid%2Fen.wikipedia.org%3AH.261" class="Z3988"></span></span> </li> <li id="cite_note-H2611993-7"><span class="mw-cite-backlink">^ <a href="#cite_ref-H2611993_7-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-H2611993_7-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFITU-T1993" class="citation web cs1">ITU-T (1993). <a rel="nofollow" class="external text" href="http://www.itu.int/rec/T-REC-H.261-199303-I/en">"H.261 : Video codec for audiovisual services at p x 64 kbit/s - Recommendation H.261 (03/93)"</a><span class="reference-accessdate">. Retrieved <span class="nowrap">2015-12-10</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=H.261+%3A+Video+codec+for+audiovisual+services+at+p+x+64+kbit%2Fs+-+Recommendation+H.261+%2803%2F93%29&rft.date=1993&rft.au=ITU-T&rft_id=http%3A%2F%2Fwww.itu.int%2Frec%2FT-REC-H.261-199303-I%2Fen&rfr_id=info%3Asid%2Fen.wikipedia.org%3AH.261" class="Z3988"></span></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">N. Ahmed, T. Natarajan and K. R. Rao, "Discrete Cosine Transform", <i>IEEE Transactions on Computers</i>, Jan. 1974, pp. 90-93; <a rel="nofollow" class="external text" href="http://dasan.sejong.ac.kr/~dihan/dip/p5_DCT.pdf">PDF file</a> <a rel="nofollow" class="external text" href="https://web.archive.org/web/20111125071212/http://dasan.sejong.ac.kr/~dihan/dip/p5_DCT.pdf">Archived</a> 2011-11-25 at the <a href="/wiki/Wayback_Machine" title="Wayback Machine">Wayback Machine</a>.</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://www.itu.int/ITU-T/recommendations/related_ps.aspx?id_prod=1088">"ITU-T Recommendation declared patent(s)"</a>. <i>ITU</i><span class="reference-accessdate">. Retrieved <span class="nowrap">12 July</span> 2019</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=ITU&rft.atitle=ITU-T+Recommendation+declared+patent%28s%29&rft_id=https%3A%2F%2Fwww.itu.int%2FITU-T%2Frecommendations%2Frelated_ps.aspx%3Fid_prod%3D1088&rfr_id=info%3Asid%2Fen.wikipedia.org%3AH.261" 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 class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.itu.int/net4/ipr/details_ps.aspx?sector=ITU-T&id=H261-07">"Patent statement declaration registered as H261-07"</a>. <i>ITU</i><span class="reference-accessdate">. Retrieved <span class="nowrap">11 July</span> 2019</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=ITU&rft.atitle=Patent+statement+declaration+registered+as+H261-07&rft_id=https%3A%2F%2Fwww.itu.int%2Fnet4%2Fipr%2Fdetails_ps.aspx%3Fsector%3DITU-T%26id%3DH261-07&rfr_id=info%3Asid%2Fen.wikipedia.org%3AH.261" class="Z3988"></span></span> </li> </ol></div></div> <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=H.261&action=edit&section=7" title="Edit section: External links"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a rel="nofollow" class="external text" href="http://www.itu.int/rec/T-REC-H.261">H.261 (03/93): Video codec for audiovisual services at p x 64 kbit/s</a> (<a href="/wiki/ITU" class="mw-redirect" title="ITU">ITU</a>)</li></ul> 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title="Data compression">compression</a> and <a href="/wiki/Container_format_(computing)" class="mw-redirect" title="Container format (computing)">container</a> formats</div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Video_coding_format" title="Video coding format">Video<br />compression</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" 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:5em"><a href="/wiki/International_Organization_for_Standardization" title="International Organization for Standardization">ISO</a>, <a href="/wiki/International_Electrotechnical_Commission" title="International Electrotechnical Commission">IEC</a>, <br /><a href="/wiki/Moving_Picture_Experts_Group" title="Moving Picture Experts Group">MPEG</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/DV_(video_format)" title="DV (video format)">DV</a></li> <li><a href="/wiki/Motion_JPEG" title="Motion JPEG">MJPEG</a></li> <li><a href="/wiki/Motion_JPEG_2000" title="Motion JPEG 2000">Motion JPEG 2000</a></li> <li><a href="/wiki/MPEG-1" title="MPEG-1">MPEG-1</a></li> <li><a href="/wiki/MPEG-2" title="MPEG-2">MPEG-2</a> <ul><li><a href="/wiki/H.262/MPEG-2_Part_2" title="H.262/MPEG-2 Part 2">Part 2</a></li></ul></li> <li><a href="/wiki/MPEG-4" title="MPEG-4">MPEG-4</a> <ul><li><a href="/wiki/MPEG-4_Part_2" title="MPEG-4 Part 2">Part 2 / ASP</a></li> <li><a href="/wiki/H.264/MPEG-4_AVC" class="mw-redirect" title="H.264/MPEG-4 AVC">Part 10 / AVC</a></li> <li><a href="/wiki/MPEG-4_IVC" class="mw-redirect" title="MPEG-4 IVC">Part 33 / IVC</a></li></ul></li> <li><a href="/wiki/MPEG-H" title="MPEG-H">MPEG-H</a> <ul><li><a href="/wiki/High_Efficiency_Video_Coding" title="High Efficiency Video Coding">Part 2 / HEVC</a></li></ul></li> <li><a href="/w/index.php?title=MPEG-I&action=edit&redlink=1" class="new" title="MPEG-I (page does not exist)">MPEG-I</a> <ul><li><a href="/wiki/Versatile_Video_Coding" title="Versatile Video Coding">Part 3 / VVC</a></li></ul></li> <li><a href="/wiki/MPEG-5" class="mw-redirect" title="MPEG-5">MPEG-5</a> <ul><li><a href="/wiki/Essential_Video_Coding" title="Essential Video Coding">Part 1 / EVC</a></li> <li><a href="/wiki/LCEVC" title="LCEVC">Part 2 / LCEVC</a></li></ul></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:5em"><a href="/wiki/ITU-T" title="ITU-T">ITU-T</a>, <a href="/wiki/Video_Coding_Experts_Group" title="Video Coding Experts Group">VCEG</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/H.120" title="H.120">H.120</a></li> <li><a class="mw-selflink selflink">H.261</a></li> <li><a href="/wiki/H.262/MPEG-2_Part_2" title="H.262/MPEG-2 Part 2">H.262</a></li> <li><a href="/wiki/H.263" title="H.263">H.263</a></li> <li><a href="/wiki/Advanced_Video_Coding" title="Advanced Video Coding">H.264 / AVC</a></li> <li><a href="/wiki/High_Efficiency_Video_Coding" title="High Efficiency Video Coding">H.265 / HEVC</a></li> <li><a href="/wiki/Versatile_Video_Coding" title="Versatile Video Coding">H.266 / VVC</a></li> <li><a href="/w/index.php?title=H.267&action=edit&redlink=1" class="new" title="H.267 (page does not exist)">H.267 / Enhanced Coding Model</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:5em"><a href="/wiki/Society_of_Motion_Picture_and_Television_Engineers" title="Society of Motion Picture and Television Engineers">SMPTE</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/VC-1" title="VC-1">VC-1</a></li> <li><a href="/wiki/Dirac_(video_compression_format)" title="Dirac (video compression format)">VC-2</a></li> <li><a href="/wiki/Avid_DNxHD" title="Avid DNxHD">VC-3</a></li> <li><a href="/wiki/CineForm" title="CineForm">VC-5</a></li> <li><a href="/wiki/VC-6" title="VC-6">VC-6</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:5em"><a href="/wiki/On2_Technologies" title="On2 Technologies">TrueMotion</a> and AOMedia</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/On2_Technologies#TrueMotion_S" title="On2 Technologies">TrueMotion S</a></li> <li><a href="/wiki/VP3" title="VP3">VP3</a></li> <li><a href="/wiki/VP6" title="VP6">VP6</a></li> <li><a href="/wiki/VP7" class="mw-redirect" title="VP7">VP7</a></li> <li><a href="/wiki/VP8" title="VP8">VP8</a></li> <li><a href="/wiki/VP9" title="VP9">VP9</a></li> <li><a href="/wiki/AV1" title="AV1">AV1</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:5em">Chinese Standard</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/Audio_Video_Standard#First_generation" title="Audio Video Standard">AVS1 P2/AVS+</a>(GB/T 20090.2/16)</li> <li><a href="/wiki/Audio_Video_Standard#Second_generation" title="Audio Video Standard">AVS2 P2</a>(GB/T 33475.2,GY/T 299.1) <ul><li>HDR Vivid(GY/T 358)</li></ul></li> <li>AVS3 P2(GY/T 368)</li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:5em">Others</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/Apple_Video" title="Apple Video">Apple Video</a></li> <li><a href="/wiki/Audio_Video_Standard" title="Audio Video Standard">AVS</a></li> <li><a href="/wiki/Bink_Video" title="Bink Video">Bink</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/Digital_Video_Interactive" title="Digital Video Interactive">DVI</a></li> <li><a href="/wiki/FFV1" title="FFV1">FFV1</a></li> <li><a href="/wiki/Huffyuv" title="Huffyuv">Huffyuv</a></li> <li><a href="/wiki/Indeo" title="Indeo">Indeo</a></li> <li><a href="/wiki/Lagarith" title="Lagarith">Lagarith</a></li> <li><a href="/wiki/Microsoft_Video_1" title="Microsoft Video 1">Microsoft Video 1</a></li> <li><a href="/wiki/MSU_Lossless_Video_Codec" title="MSU Lossless Video Codec">MSU Lossless</a></li> <li><a href="/wiki/OMS_Video" title="OMS Video">OMS Video</a></li> <li><a href="/wiki/Pixlet" title="Pixlet">Pixlet</a></li> <li><a href="/wiki/Apple_ProRes" title="Apple ProRes">ProRes</a> <ul><li><a href="/wiki/ProRes_422" class="mw-redirect" title="ProRes 422">422</a></li> <li><a href="/wiki/ProRes_4444" class="mw-redirect" title="ProRes 4444">4444</a></li></ul></li> <li>QuickTime <ul><li><a href="/wiki/QuickTime_Animation" title="QuickTime Animation">Animation</a></li> <li><a href="/wiki/QuickTime_Graphics" title="QuickTime Graphics">Graphics</a></li></ul></li> <li><a href="/wiki/RealVideo" title="RealVideo">RealVideo</a></li> <li><a href="/wiki/RTVideo" title="RTVideo">RTVideo</a></li> <li><a href="/wiki/SheerVideo" title="SheerVideo">SheerVideo</a></li> <li><a href="/wiki/Smacker_video" title="Smacker video">Smacker</a></li> <li><a href="/wiki/Sorenson_Media" title="Sorenson Media">Sorenson Video/Spark</a></li> <li><a href="/wiki/Theora" title="Theora">Theora</a></li> <li><a href="/wiki/Thor_(video_codec)" title="Thor (video codec)">Thor</a></li> <li><a href="/wiki/Ut_Video_Codec_Suite" title="Ut Video Codec Suite">Ut</a></li> <li><a href="/wiki/Windows_Media_Video" title="Windows Media Video">WMV</a></li> <li><a href="/wiki/RatDVD" title="RatDVD">XEB</a></li> <li><a href="/wiki/YULS" title="YULS">YULS</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/Audio_coding_format" title="Audio coding format">Audio<br />compression</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" 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:5em"><a href="/wiki/International_Organization_for_Standardization" title="International Organization for Standardization">ISO</a>, <a href="/wiki/International_Electrotechnical_Commission" title="International Electrotechnical Commission">IEC</a>,<br /> <a href="/wiki/Moving_Picture_Experts_Group" title="Moving Picture Experts Group">MPEG</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/MPEG-1_Audio_Layer_II" title="MPEG-1 Audio Layer II">MPEG-1 Layer II</a> <ul><li><a href="/wiki/MPEG_Multichannel" title="MPEG Multichannel">Multichannel</a></li></ul></li> <li><a href="/wiki/MPEG-1_Audio_Layer_I" title="MPEG-1 Audio Layer I">MPEG-1 Layer I</a></li> <li><a href="/wiki/MP3" title="MP3">MPEG-1 Layer III (MP3)</a></li> <li><a href="/wiki/Advanced_Audio_Coding" title="Advanced Audio Coding">AAC</a> <ul><li><a href="/wiki/High-Efficiency_Advanced_Audio_Coding" title="High-Efficiency Advanced Audio Coding">HE-AAC</a></li> <li><a href="/wiki/AAC-LD" title="AAC-LD">AAC-LD</a></li></ul></li> <li><a href="/wiki/MPEG_Surround" title="MPEG Surround">MPEG Surround</a></li> <li><a href="/wiki/Audio_Lossless_Coding" title="Audio Lossless Coding">MPEG-4 ALS</a></li> <li><a href="/wiki/MPEG-4_SLS" title="MPEG-4 SLS">MPEG-4 SLS</a></li> <li><a href="/wiki/Super_Audio_CD#DST" title="Super Audio CD">MPEG-4 DST</a></li> <li><a href="/wiki/Harmonic_Vector_Excitation_Coding" title="Harmonic Vector Excitation Coding">MPEG-4 HVXC</a></li> <li><a href="/wiki/Code-excited_linear_prediction" title="Code-excited linear prediction">MPEG-4 CELP</a></li> <li><a href="/wiki/Unified_Speech_and_Audio_Coding" title="Unified Speech and Audio Coding">MPEG-D USAC</a></li> <li><a href="/wiki/MPEG-H_3D_Audio" title="MPEG-H 3D Audio">MPEG-H 3D Audio</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:5em"><a href="/wiki/ITU-T" title="ITU-T">ITU-T</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/G.711" title="G.711">G.711</a> <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></ul></li> <li><a href="/wiki/G.718" title="G.718">G.718</a></li> <li><a href="/wiki/G.719" title="G.719">G.719</a></li> <li><a href="/wiki/G.722" title="G.722">G.722</a></li> <li><a href="/wiki/G.722.1" title="G.722.1">G.722.1</a></li> <li><a href="/wiki/Adaptive_Multi-Rate_Wideband" title="Adaptive Multi-Rate Wideband">G.722.2</a></li> <li><a href="/wiki/G.723" title="G.723">G.723</a></li> <li><a href="/wiki/G.723.1" title="G.723.1">G.723.1</a></li> <li><a href="/wiki/G.726" title="G.726">G.726</a></li> <li><a href="/wiki/G.728" title="G.728">G.728</a></li> <li><a href="/wiki/G.729" title="G.729">G.729</a></li> <li><a href="/wiki/G.729.1" title="G.729.1">G.729.1</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:5em"><a href="/wiki/Internet_Engineering_Task_Force" title="Internet Engineering Task Force">IETF</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/Opus_(audio_format)" title="Opus (audio format)">Opus</a></li> <li><a href="/wiki/Internet_Low_Bitrate_Codec" title="Internet Low Bitrate Codec">iLBC</a></li> <li><a href="/wiki/Speex" title="Speex">Speex</a></li> <li><a href="/wiki/Vorbis" title="Vorbis">Vorbis</a></li> <li><a href="/wiki/FLAC" title="FLAC">FLAC</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:5em"><a href="/wiki/3GPP" title="3GPP">3GPP</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/Adaptive_Multi-Rate_audio_codec" title="Adaptive Multi-Rate audio codec">AMR</a></li> <li><a href="/wiki/Adaptive_Multi-Rate_Wideband" title="Adaptive Multi-Rate Wideband">AMR-WB</a></li> <li><a href="/wiki/Extended_Adaptive_Multi-Rate_%E2%80%93_Wideband" title="Extended Adaptive Multi-Rate – Wideband">AMR-WB+</a></li> <li><a href="/wiki/Enhanced_Variable_Rate_Codec" title="Enhanced Variable Rate Codec">EVRC</a></li> <li><a href="/wiki/Enhanced_Variable_Rate_Codec_B" title="Enhanced Variable Rate Codec B">EVRC-B</a></li> <li><a href="/wiki/Enhanced_Voice_Services" title="Enhanced Voice Services">EVS</a></li> <li><a href="/wiki/Half_Rate" title="Half Rate">GSM-HR</a></li> <li><a href="/wiki/Full_Rate" title="Full Rate">GSM-FR</a></li> <li><a href="/wiki/Enhanced_full_rate" title="Enhanced full rate">GSM-EFR</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:5em"><a href="/wiki/ETSI" class="mw-redirect" title="ETSI">ETSI</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/Dolby_Digital" title="Dolby Digital">AC-3</a></li> <li><a href="/wiki/Dolby_AC-4" title="Dolby AC-4">AC-4</a></li> <li><a href="/wiki/DTS_(sound_system)" class="mw-redirect" title="DTS (sound system)">DTS</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:5em"><a href="/wiki/Bluetooth_Special_Interest_Group" title="Bluetooth Special Interest Group">Bluetooth SIG</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/SBC_(codec)" title="SBC (codec)">SBC</a></li> <li><a href="/wiki/LC3_(codec)" title="LC3 (codec)">LC3</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:5em">Chinese Standard</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/Audio_Video_Standard#First_generation" title="Audio Video Standard">AVS1 P10</a>(GB/T 20090.10)</li> <li><a href="/wiki/Audio_Video_Standard#Second_generation" title="Audio Video Standard">AVS2 P3</a>(GB/T 33475.3) <ul><li><a href="/w/index.php?title=Audio_Vivid&action=edit&redlink=1" class="new" title="Audio Vivid (page does not exist)">Audio Vivid</a>(GY/T 363)</li></ul></li> <li><a href="/wiki/Dynamic_Resolution_Adaptation" title="Dynamic Resolution Adaptation">DRA</a>(GB/T 22726)</li> <li>ExAC(SJ/T 11299.4)</li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:5em">Others</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/Algebraic_code-excited_linear_prediction" title="Algebraic code-excited linear prediction">ACELP</a></li> <li><a href="/wiki/Apple_Lossless_Audio_Codec" title="Apple Lossless Audio Codec">ALAC</a></li> <li><a href="/wiki/Asao_(codec)" title="Asao (codec)">Asao</a></li> <li><a href="/wiki/Adaptive_Transform_Acoustic_Coding" class="mw-redirect" title="Adaptive Transform Acoustic Coding">ATRAC</a></li> <li><a href="/wiki/CELT" title="CELT">CELT</a></li> <li><a href="/wiki/Codec_2" title="Codec 2">Codec 2</a></li> <li><a href="/wiki/Internet_Speech_Audio_Codec" title="Internet Speech Audio Codec">iSAC</a></li> <li><a href="/wiki/Lyra_(codec)" title="Lyra (codec)">Lyra</a></li> <li><a href="/wiki/Mixed-excitation_linear_prediction" title="Mixed-excitation linear prediction">MELP</a></li> <li><a href="/wiki/Monkey%27s_Audio" title="Monkey's Audio">Monkey's Audio</a></li> <li><a href="/wiki/MT9" title="MT9">MT9</a></li> <li><a href="/wiki/Musepack" title="Musepack">Musepack</a></li> <li><a href="/wiki/OptimFROG" title="OptimFROG">OptimFROG</a></li> <li><a href="/wiki/Original_Sound_Quality" title="Original Sound Quality">OSQ</a></li> <li><a href="/wiki/Qualcomm_code-excited_linear_prediction" title="Qualcomm code-excited linear prediction">QCELP</a></li> <li><a href="/wiki/Relaxed_code-excited_linear_prediction" title="Relaxed code-excited linear prediction">RCELP</a></li> <li><a href="/wiki/RealAudio" title="RealAudio">RealAudio</a></li> <li><a href="/wiki/Avid_Audio#Sound_Designer_file_formats" title="Avid Audio">SD2</a></li> <li><a href="/wiki/Shorten_file_format" class="mw-redirect" title="Shorten file format">SHN</a></li> <li><a href="/wiki/SILK" title="SILK">SILK</a></li> <li><a href="/wiki/Siren_(codec)" title="Siren (codec)">Siren</a></li> <li><a href="/wiki/Selectable_Mode_Vocoder" title="Selectable Mode Vocoder">SMV</a></li> <li><a href="/wiki/SVOPC" title="SVOPC">SVOPC</a></li> <li>TTA <ul><li>True Audio</li></ul></li> <li><a href="/wiki/TwinVQ" title="TwinVQ">TwinVQ</a></li> <li><a href="/wiki/Variable-Rate_Multimode_Wideband" title="Variable-Rate Multimode Wideband">VMR-WB</a></li> <li><a href="/wiki/Vector_sum_excited_linear_prediction" title="Vector sum excited linear prediction">VSELP</a></li> <li><a href="/wiki/WavPack" title="WavPack">WavPack</a></li> <li><a href="/wiki/Windows_Media_Audio" title="Windows Media Audio">WMA</a></li> <li><a href="/wiki/Master_Quality_Authenticated" title="Master Quality Authenticated">MQA</a></li> <li><a href="/wiki/AptX" title="AptX">aptX</a></li> <li><a href="/wiki/AptX#aptX_HD" title="AptX">aptX HD</a></li> <li><a href="/wiki/AptX#aptX_Low_Latency" title="AptX">aptX Low Latency</a></li> <li><a href="/wiki/AptX#aptX_Adaptive" title="AptX">aptX Adaptive</a></li> <li><a href="/wiki/LDAC_(codec)" title="LDAC (codec)">LDAC</a></li> <li><a href="/wiki/LHDC_(codec)" title="LHDC (codec)">LHDC</a></li> <li><a href="/wiki/LHDC_(codec)#LLAC" title="LHDC (codec)">LLAC</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<br />compression</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" 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:5em"><a href="/wiki/International_Electrotechnical_Commission" title="International Electrotechnical Commission">IEC</a>, <a href="/wiki/International_Organization_for_Standardization" title="International Organization for Standardization">ISO</a>, <a href="/wiki/Internet_Engineering_Task_Force" title="Internet Engineering Task Force">IETF</a>, <br /><a href="/wiki/World_Wide_Web_Consortium" title="World Wide Web Consortium">W3C</a>, <a href="/wiki/ITU-T" title="ITU-T">ITU-T</a>, <a href="/wiki/Joint_Photographic_Experts_Group" title="Joint Photographic Experts Group">JPEG</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/Group_4_compression" title="Group 4 compression">CCITT Group 4</a></li> <li><a href="/wiki/GIF" title="GIF">GIF</a></li> <li><a href="/wiki/High_Efficiency_Image_File_Format#HEIC:_HEVC_in_HEIF" title="High Efficiency Image File Format">HEIC / HEIF</a></li> <li><a href="/wiki/High_Efficiency_Video_Coding#Main_Still_Picture" title="High Efficiency Video Coding">HEVC</a></li> <li><a href="/wiki/JBIG" title="JBIG">JBIG</a></li> <li><a href="/wiki/JBIG2" title="JBIG2">JBIG2</a></li> <li><a href="/wiki/JPEG" title="JPEG">JPEG</a></li> <li><a href="/wiki/JPEG_2000" title="JPEG 2000">JPEG 2000</a></li> <li><a href="/wiki/JPEG-LS" class="mw-redirect" title="JPEG-LS">JPEG-LS</a></li> <li><a href="/wiki/JPEG_XL" title="JPEG XL">JPEG XL</a></li> <li><a href="/wiki/JPEG_XR" title="JPEG XR">JPEG XR</a></li> <li><a href="/wiki/JPEG_XS" title="JPEG XS">JPEG XS</a></li> <li><a href="/wiki/JPEG_XT" title="JPEG XT">JPEG XT</a></li> <li><a href="/wiki/Portable_Network_Graphics" class="mw-redirect" title="Portable Network Graphics">PNG</a></li> <li><a href="/wiki/TIFF" title="TIFF">TIFF</a></li> <li><a href="/wiki/TIFF/EP" title="TIFF/EP">TIFF/EP</a></li> <li><a href="/wiki/TIFF/IT" class="mw-redirect" title="TIFF/IT">TIFF/IT</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:5em">Others</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/APNG" title="APNG">APNG</a></li> <li><a href="/wiki/AV1" title="AV1">AV1</a></li> <li><a href="/wiki/AVIF" title="AVIF">AVIF</a></li> <li><a href="/wiki/Better_Portable_Graphics" title="Better Portable Graphics">BPG</a></li> <li><a href="/wiki/DjVu" title="DjVu">DjVu</a></li> <li><a href="/wiki/OpenEXR" title="OpenEXR">EXR</a></li> <li><a href="/wiki/Free_Lossless_Image_Format" title="Free Lossless Image Format">FLIF</a></li> <li><a href="/wiki/ICER_(file_format)" title="ICER (file format)">ICER</a></li> <li><a href="/wiki/Multiple-image_Network_Graphics" title="Multiple-image Network Graphics">MNG</a></li> <li><a href="/wiki/Progressive_Graphics_File" title="Progressive Graphics File">PGF</a></li> <li><a href="/wiki/QOI_(image_format)" title="QOI (image format)">QOI</a></li> <li><a href="/wiki/QuickTime_VR" title="QuickTime VR">QTVR</a></li> <li><a href="/wiki/Wireless_Application_Protocol_Bitmap_Format" title="Wireless Application Protocol Bitmap Format">WBMP</a></li> <li><a href="/wiki/WebP" title="WebP">WebP</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/Digital_container_format" class="mw-redirect" title="Digital container format">Containers</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" 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:5em"><a href="/wiki/International_Organization_for_Standardization" title="International Organization for Standardization">ISO</a>, <a href="/wiki/International_Electrotechnical_Commission" title="International Electrotechnical Commission">IEC</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/MPEG_elementary_stream" title="MPEG elementary stream">MPEG-ES</a> <ul><li><a href="/wiki/Packetized_elementary_stream" title="Packetized elementary stream">MPEG-PES</a></li></ul></li> <li><a href="/wiki/MPEG_program_stream" title="MPEG program stream">MPEG-PS</a></li> <li><a href="/wiki/MPEG_transport_stream" title="MPEG transport stream">MPEG-TS</a></li> <li><a href="/wiki/ISO/IEC_base_media_file_format" class="mw-redirect" title="ISO/IEC base media file format">ISO/IEC base media file format</a></li> <li><a href="/wiki/MPEG-4_Part_14" class="mw-redirect" title="MPEG-4 Part 14">MPEG-4 Part 14</a> (MP4)</li> <li><a href="/wiki/Motion_JPEG_2000" title="Motion JPEG 2000">Motion JPEG 2000</a></li> <li><a href="/wiki/MPEG-21" title="MPEG-21">MPEG-21 Part 9</a></li> <li><a href="/wiki/MPEG_media_transport" title="MPEG media transport">MPEG media transport</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:5em"><a href="/wiki/ITU-T" title="ITU-T">ITU-T</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/MPEG-2#Systems" title="MPEG-2">H.222.0</a></li> <li><a href="/wiki/Motion_JPEG_2000" title="Motion JPEG 2000">T.802</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:5em"><a href="/wiki/Internet_Engineering_Task_Force" title="Internet Engineering Task Force">IETF</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/Real-time_Transport_Protocol" title="Real-time Transport Protocol">RTP</a></li> <li><a href="/wiki/Ogg" title="Ogg">Ogg</a></li> <li><a href="/wiki/Matroska" title="Matroska">Matroska</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:5em"><a href="/wiki/Society_of_Motion_Picture_and_Television_Engineers" title="Society of Motion Picture and Television Engineers">SMPTE</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/General_Exchange_Format" title="General Exchange Format">GXF</a></li> <li><a href="/wiki/Material_Exchange_Format" title="Material Exchange Format">MXF</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:5em">Others</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/3GP_and_3G2" title="3GP and 3G2">3GP and 3G2</a></li> <li><a href="/wiki/AMV_video_format" title="AMV video format">AMV</a></li> <li><a href="/wiki/Advanced_Systems_Format" title="Advanced Systems Format">ASF</a></li> <li><a href="/wiki/Audio_Interchange_File_Format" title="Audio Interchange File Format">AIFF</a></li> <li><a href="/wiki/Audio_Video_Interleave" title="Audio Video Interleave">AVI</a></li> <li><a href="/wiki/Au_file_format" title="Au file format">AU</a></li> <li><a href="/wiki/Better_Portable_Graphics" title="Better Portable Graphics">BPG</a></li> <li><a href="/wiki/Bink_Video" title="Bink Video">Bink</a> <ul><li><a href="/wiki/Smacker_video" title="Smacker video">Smacker</a></li></ul></li> <li><a href="/wiki/BMP_file_format" title="BMP file format">BMP</a></li> <li><a href="/wiki/DivX#DivX_Media_Format_(DMF)" title="DivX">DivX Media Format</a></li> <li><a href="/wiki/Enhanced_VOB" title="Enhanced VOB">EVO</a></li> <li><a href="/wiki/Flash_Video" title="Flash Video">Flash Video</a></li> <li><a href="/wiki/High_Efficiency_Image_File_Format" title="High Efficiency Image File Format">HEIF</a></li> <li><a href="/wiki/Interchange_File_Format" title="Interchange File Format">IFF</a></li> <li><a href="/wiki/.m2ts" title=".m2ts">M2TS</a></li> <li><a href="/wiki/Matroska" title="Matroska">Matroska</a> <ul><li><a href="/wiki/WebM" title="WebM">WebM</a></li></ul></li> <li><a href="/wiki/QuickTime_File_Format" title="QuickTime File Format">QuickTime File Format</a></li> <li><a href="/wiki/RatDVD" title="RatDVD">RatDVD</a></li> <li><a href="/wiki/RealMedia" title="RealMedia">RealMedia</a></li> <li><a href="/wiki/Resource_Interchange_File_Format" title="Resource Interchange File Format">RIFF</a> <ul><li><a href="/wiki/WAV" title="WAV">WAV</a></li></ul></li> <li><a href="/wiki/MOD_and_TOD" title="MOD and TOD">MOD and TOD</a></li> <li><a href="/wiki/VOB" title="VOB">VOB, IFO and BUP</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Collaborations</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/NETVC" title="NETVC">NETVC</a></li> <li><a href="/wiki/MPEG_LA" title="MPEG LA">MPEG LA</a></li> <li><a href="/wiki/Alliance_for_Open_Media" title="Alliance for Open Media">Alliance for Open Media</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Data_compression" title="Data compression">Methods</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Entropy_encoding" class="mw-redirect" title="Entropy encoding">Entropy</a> <ul><li><a href="/wiki/Arithmetic_coding" title="Arithmetic coding">Arithmetic</a></li> <li><a href="/wiki/Huffman_coding" title="Huffman coding">Huffman</a></li> <li><a href="/wiki/Modified_Huffman_coding" title="Modified Huffman coding">Modified</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/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/Lossless_compression" title="Lossless compression">Lossless</a></li> <li><a href="/wiki/Lossy_compression" title="Lossy compression">Lossy</a></li> <li><a href="/wiki/LZ77_and_LZ78" title="LZ77 and LZ78">LZ</a> <ul><li><a href="/wiki/DEFLATE" class="mw-redirect" title="DEFLATE">DEFLATE</a></li> <li><a href="/wiki/Lempel%E2%80%93Ziv%E2%80%93Welch" title="Lempel–Ziv–Welch">LZW</a></li></ul></li> <li><a href="/wiki/Pulse-code_modulation" title="Pulse-code modulation">PCM</a> <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/Adaptive_differential_pulse-code_modulation" title="Adaptive differential pulse-code modulation">ADPCM</a></li> <li><a href="/wiki/Differential_pulse-code_modulation" title="Differential pulse-code modulation">DPCM</a></li></ul></li> <li><a href="/wiki/Transform_coding" title="Transform coding">Transforms</a> <ul><li><a href="/wiki/Discrete_cosine_transform" title="Discrete cosine transform">DCT</a></li> <li><a href="/wiki/Fast_Fourier_transform" title="Fast Fourier transform">FFT</a></li> <li><a href="/wiki/Modified_discrete_cosine_transform" title="Modified discrete cosine transform">MDCT</a></li> <li><a href="/wiki/Wavelet" title="Wavelet">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></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Lists</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Comparison_of_audio_coding_formats" title="Comparison of audio coding formats">Comparison of audio coding formats</a></li> <li><a href="/wiki/Comparison_of_video_codecs" title="Comparison of video codecs">Comparison of video codecs</a></li> <li><a href="/wiki/List_of_codecs" title="List of codecs">List of codecs</a></li></ul> </div></td></tr><tr><td class="navbox-abovebelow" colspan="2"><div>See <a href="/wiki/Template:Compression_methods" title="Template:Compression methods">Compression methods</a> for techniques and <a href="/wiki/Template:Compression_software" title="Template:Compression software">Compression software</a> for codecs</div></td></tr></tbody></table></div>    </div><noscript><img src="https://login.wikimedia.org/wiki/Special:CentralAutoLogin/start?useformat=desktop&type=1x1&usesul3=0" alt="" width="1" height="1" style="border: none; position: absolute;"></noscript> <div class="printfooter" data-nosnippet="">Retrieved from "<a dir="ltr" href="https://en.wikipedia.org/w/index.php?title=H.261&oldid=1226741980">https://en.wikipedia.org/w/index.php?title=H.261&oldid=1226741980</a>"</div></div> <div id="catlinks" class="catlinks" data-mw="interface"><div id="mw-normal-catlinks" class="mw-normal-catlinks"><a href="/wiki/Help:Category" title="Help:Category">Categories</a>: <ul><li><a href="/wiki/Category:Video_codecs" title="Category:Video codecs">Video codecs</a></li><li><a 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