Speed Class | SD Association

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By developing and adopting SD standards, members enjoy better compatibility of member cards between devices, greatly enhancing consumer enjoyment and convenience.</p> </div> </li> </ul> </li></div> </ul></div> </li> <li class="mega-menu-list dc-mega-li"> <a href="https://www.sdcard.org/consumers/" class="mega-menu-list-ttl dc-mega">Consumers<span class="dc-mega-icon"></span></a> <div class="sub-container mega" style="left: 0px; top: 40px; z-index: 1000;"><ul class="relative sub" style="display: none;"> <div class="row" style="width: 980px;"><li class="megabox mega-unit mega-hdr last" style="height: 321px;"><span class="triangle triangle_2"></span> <ul class="gnav_2_a_box"> <li> <ul class="linklist"> <li><a href="https://www.sdcard.org/consumers/about-sd-memory-card-choices/">About SD Memory Card Choices</a> <ul> <li><a href="https://www.sdcard.org/consumers/about-sd-memory-card-choices/sd-sdhc-sdxc-and-sduc-card-capacity-choices/">SD, SDHC, SDXC and SDUC Card Capacity Choices</a></li> <li><a href="https://www.sdcard.org/consumers/about-sd-memory-card-choices/bus-interface-speed-standards-for-large-size-data-transfer/">Bus Interface Speed Standards for Large Size Data Transfer</a></li> <li><a href="https://www.sdcard.org/consumers/about-sd-memory-card-choices/speed-class-standards-for-video-recording/">Speed Class Standards for Video Recording</a></li> <li><a href="https://www.sdcard.org/consumers/about-sd-memory-card-choices/application-performance-class-for-running-smartphone-apps/">Application Performance Class for Running Smartphone Apps</a></li> <li><a href="https://www.sdcard.org/consumers/about-sd-memory-card-choices/low-voltage-signaling/">Low Voltage Signaling</a></li> <li><a href="https://www.sdcard.org/consumers/about-sd-memory-card-choices/copyright-protection-for-digital-data-cprm/">Copyright Protection for Digital Data (CPRM)</a></li> </ul> </li> </ul> </li> </ul> <ul class="gnav_2_b_box"> <li> <ul class="linklist"> <li><a href="https://www.sdcard.org/svp/">SD Express / UHS-II Verification Program (SVP) Verified Product</a></li> <li><a href="https://www.sdcard.org/consumers/choosemicrosd/">#choosemicroSD</a></li> <li><a href="https://www.sdcard.org/consumers/usage-tip-videos/">Usage Tip Videos</a></li> <li><a href="https://www.sdcard.org/consumers/faq/">FAQ</a></li> </ul> </li> </ul> <ul class="gnav_2_c_box"> <li> <div class="bg-navy"><span class="fr ml20 mb10"><img src="https://www.sdcard.org/cms/wp-content/themes/sdcard-org/library/images/gnav2_img01.jpg" alt="" width="171" height="173"></span> <p>Consumers</p> <p class="f_size12">The SD Association has prepared multiple SD standards relating to such features as memory capacity and reading/writing speed in order for users to select the optimum card for their device.</p> </div> </li> </ul> </li></div> </ul></div> </li> <li class="mega-menu-list dc-mega-li"> <a href="https://www.sdcard.org/developers/" class="mega-menu-list-ttl dc-mega">Developers<span 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href="https://www.sdcard.org/developers/boot-and-new-security-features/">Boot and Extended Security Features (RPMB and TCG)</a> <ul> <li><a href="https://www.sdcard.org/developers/boot-and-new-security-features/boot-function/">Boot (secured and fast)</a></li> <li><a href="https://www.sdcard.org/developers/boot-and-new-security-features/tcg-storage-in-sd-memory-cards/">TCG</a></li> <li><a href="https://www.sdcard.org/developers/boot-and-new-security-features/replay-protected-memory-block/">RPMB</a></li> </ul> </li> <li><a href="https://www.sdcard.org/developers/sd-standard-overview/speed-class/">Speed Class</a></li> <li><a class="level_3" href="https://www.sdcard.org/developers/sd-standard-overview/application-performance-class/">Application  Performance Class</a></li> <li><a class="level_3" href="https://www.sdcard.org/developers/sd-standard-overview/low-voltage-signaling/">Low Voltage Signaling</a></li> <li><a href="https://www.sdcard.org/developers/sd-standard-overview/content-protection/">Content Protection</a></li> <li><a href="https://www.sdcard.org/developers/sd-standard-overview/host-controllers/">Host Controllers</a> </li> </ul> </li> </ul> </li> </ul> <ul class="gnav_3_b_box"> <li> <ul class="linklist"> <li class="noliststyle">  <ul> <li><a href="https://www.sdcard.org/developers/sd-standard-overview/sdio-isdio/">SDIO/iSDIO</a> <ul> <li><a href="https://www.sdcard.org/developers/sd-standard-overview/sdio-isdio/wireless-lan-sd/">Wireless LAN SD</a></li> <li><a href="https://www.sdcard.org/developers/sd-standard-overview/sdio-isdio/transferjet-sd/">TransferJet SD</a></li> </ul> </li> <li><a href="https://www.sdcard.org/developers/sd-standard-overview/assd/">ASSD</a> <ul> <li><a href="https://www.sdcard.org/developers/sd-standard-overview/assd/smartsd/">smartSD</a></li> </ul> </li> </ul> </li> </ul> </li> </ul> <ul class="gnav_3_c_box"> <li> <ul class="linklist"> <li class="noliststyle">  <ul> <li><a href="https://www.sdcard.org/developers/sd-standard-overview/embedded-sd/">Embedded SD</a></li> <li><a href="https://www.sdcard.org/developers/sd-standard-overview/application-formats/">Application Formats</a> <ul> <li><a href="https://www.sdcard.org/developers/sd-standard-overview/application-formats/sd-audio/">SD-Audio</a></li> <li><a href="https://www.sdcard.org/developers/sd-standard-overview/application-formats/sd-video/">SD-Video</a></li> <li><a href="https://www.sdcard.org/developers/sd-standard-overview/application-formats/sd-binding/">SD-Binding</a></li> <li><a href="https://www.sdcard.org/developers/sd-standard-overview/application-formats/sd-sd/">SD-SD</a></li> <li><a href="https://www.sdcard.org/developers/sd-standard-overview/application-formats/sd-sd-ebook/">SD-SD eBook</a></li> </ul> </li> </ul> </li> </ul> </li> </ul> <ul class="gnav_3_d_box"> <li> <ul class="linklist"> <li><a href="https://www.sdcard.org/developers/svp/">SD Express / UHS-II Verification Program (SVP) Verified Product</a></li> <li><a href="https://www.sdcard.org/developers/how-to-start-using-sd-standards-in-your-product/">How to Start Using SD Standards in Your Product</a></li> <li><a href="https://www.sdcard.org/developers/use-and-licensing/">Use and Licensing</a></li> </ul> </li> </ul> </li></div> </ul></div> </li> <li class="mega-menu-list dc-mega-li"> <a href="https://www.sdcard.org/downloads/" class="mega-menu-list-ttl dc-mega">Downloads<span class="dc-mega-icon"></span></a> <div class="sub-container mega" style="left: 0px; top: 40px; z-index: 1000;"><ul class="relative sub" style="display: none;"> <div class="row" style="width: 980px;"><li class="megabox mega-unit mega-hdr last" style="height: 400px;"><span class="triangle triangle_4"></span> <ul class="gnav_4_a_box"> <li> <ul class="linklist"> <li><a href="https://www.sdcard.org/downloads/pls/latest_whitepapers/">SD Association Whitepapers</a></li> <li><a href="https://www.sdcard.org/downloads/pls/">Simplified Specifications</a></li> <li><a href="https://www.sdcard.org/downloads/formatter/">SD Memory Card Formatter for Windows/Mac</a> <ul> <li><a href="https://www.sdcard.org/downloads/formatter/sd-memory-card-formatter-for-windows-download/">SD Memory Card Formatter for Windows Download</a></li> <li><a href="https://www.sdcard.org/downloads/formatter/sd-memory-card-formatter-for-mac-download/">SD Memory Card Formatter for Mac Download</a></li> <li><a href="https://www.sdcard.org/downloads/formatter/faq/">FAQ</a></li> </ul> </li> <li><a href="https://www.sdcard.org/downloads/sd-memory-card-formatter-for-linux/">SD Memory Card Formatter for Linux</a> <ul> <li><a href="https://www.sdcard.org/downloads/sd-memory-card-formatter-for-linux/sd-memory-card-formatter-for-linux-x86-64-download/">SD Memory Card Formatter for Linux_x86_64 Download</a></li> <li><a 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Varying speeds make it difficult to make out which card can surely record streaming contents.Recording video require a constant minimum write speed to avoid ‘frame drop’ during recording for a smooth playback. The SD Association has defined various Speed Class standards to answer a demand for advanced video quality recording. Speed Class symbols indicated to host and card products help users decide the best combination for reliable recording (no frame drop). The various speed class types assures minimum sequential card access performance including multiple stream access (in SD Express Speed Classes) under defined conditions specified in the standard. It is most important for video recording and other applications. It is also applicable for any write or read applications that requires an assured minimum constant sequential access performance.</p> <p class="mb20">There are four kinds of speed indications:</p> <img fetchpriority="high" decoding="async" class="mt20 mb20 aligncenter wp-image-4514 size-full" src="https://www.sdcard.org/cms/wp-content/uploads/2023/10/CardCameraEN.png" alt="" width="983" height="387" /> <p class="mb20"><span style="font-weight: 400;">Speed Class*, UHS Speed Class**, Video Speed Class*** </span><span style="font-weight: 400;">and SD Express Speed Class**** </span><span style="font-weight: 400;">symbols with a number indicate minimum writing speed. This is mainly useful for camcorders, video recorders and other devices with video recording capabilities. Regarding bus mode, it is necessary to use a bus mode fast enough that does not affect memory write speed. C10 is used in High Speed mode or faster, U1 and U3 are used in SDR50/DDR50 or faster , V60 and V90 are used in UHS-II mode or faster</span><span style="font-weight: 400;">, E150/E300/E450/E600 are used in SD Express mode</span><span style="font-weight: 400;">.</span></p> <p class="mb20"><span style="font-weight: 400;">Video Speed Class and SD Express Speed Class are defined to answer a demand for high resolution and high quality 4K8K video recording and it also has an important feature to support next generation flash memory such as 3D NAND. </span><span style="font-weight: 400;">In addition, the SD Express speed class supports also multi stream access.</span></p> <p class="mb20"><span style="font-weight: 400;">The main reason </span><span style="font-weight: 400;">driving</span> <span style="font-weight: 400;">many speed class types is the evolution of </span><span style="font-weight: 400;">NAND</span> <span style="font-weight: 400;">memory technology. While the early speed class types – </span><span style="font-weight: 400;">Speed Class and UHS Speed </span><span style="font-weight: 400;">Class were optimized for older memory technologies, the latest types of Video Speed Class and SD Express speed class are both optimized for the latest NAND flash technologies allowing best utilization of today’s </span><span style="font-weight: 400;">NAND technology.</span></p> <p class="mb20"><span style="font-weight: 400;">SD Express Speed Class is based on the same concepts of the Video Speed Class access methods with the following unique features:</span></p> <p><span style="font-weight: 400;">– Defined to be used with NVMe protocol</span></p> <p><span style="font-weight: 400;">– Supports multi-stream access</span></p> <p><span style="font-weight: 400;">– Power and Thermal management optimized for the speed class support.</span></p> </div> <div class="mt20 clearfix"> <div id="speedclass"> <dl class="clearfix"> <dt>*</dt> <dd><span class="smalltext2 mt10">The Speed Classes defined by the SD Association are Class 2, 4, 6 and 10. Class 10 can be applied to High Speed Bus IF product family. </span></dd> <dt>**</dt> <dd><span class="smalltext2 mt10">The UHS Speed Classes defined by the SD Association are UHS Speed Class 1 (U1) and UHS Speed Class 3 (U3). U1 and U3 can be applied to UHS Bus IF product family (UHS-I & UHS-II &UHS-III).</span></dd> <dt>***</dt> <dd><span class="smalltext2 mt10">The Video Speed Classes defined by the SD Association are V6, 10,30,60 and 90. V6 and V10 can be applied to High Speed and UHS Bus IF product family. V30 can be applied to UHS Bus IF product family. V60 and V90 can be applied to UHS-II / UHS-III product family.<br /> </span></dd> <dt>****</dt> <dd><span class="smalltext2 mt10">The SD Express Speed Classes defined by the SD Association are E150, E300, E450 and E600. These can be applied to SD Express Bus IF product family.</span></dd> </dl> </div> <p><iframe title="Introducing New Video Speed Class Standard" width="680" height="383" src="https://www.youtube.com/embed/dKy_gyt2Myc?feature=oembed" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" allowfullscreen></iframe></p> <p><strong>SD Speed Class</strong></p> <p><img decoding="async" class="mb20 aligncenter wp-image-4512 size-full" src="https://www.sdcard.org/cms/wp-content/uploads/2023/10/SpeedClass9.1EN.png" alt="" width="725" height="757" /><br /> <strong>Video Format</strong><br /> <img decoding="async" class="mb20 aligncenter wp-image-4670 size-full" src="https://www.sdcard.org/cms/wp-content/uploads/2023/10/UHDMultiStream.png" alt="" width="１３９０" height="831" /></p> <p class="mb20"><strong>*<a href="https://en.wikipedia.org/wiki/Intra-frame_coding" target="_blank" rel="noopener">Intra video</a></strong>, is a compression technique performed relative to information contained only within the current frame, and not relative to any other frame in the video sequence. Therefore, it is usually larger in size.</p> <img loading="lazy" decoding="async" class="mb20 aligncenter wp-image-4671 size-full" src="https://www.sdcard.org/cms/wp-content/uploads/2023/10/UHD.png" alt="" width="1390" height="926" /> <h2>Best Combination between Speed Class Host and Card</h2> <p class="mb20">Speed Class supported host can indicate Speed Class symbol somewhere on the product, package or manual.Consumers can find the best card for a host via Speed Class symbol match; choose the same or higher class symbol card than class symbol of the host indicated.</p> <p><span style="font-weight: 400;">For example, if your host device requires a Speed Class 4 SD memory card, you can use Speed Class 4,6 or 10 SD memory cards. If your host device requires a UHS Speed Class 1 SD memory card, you can use UHS Speed Class 1 or 3 SD memory cards. Video Speed Class </span><span style="font-weight: 400;">and SD Express Speed Class are </span><span style="font-weight: 400;">also the same. Note that expected write speed will not be available by a combination of different class symbols between host and card such as Host Class 10 and Card U1, Host U1 and Card V10, etc. even those are indicated to the same 10MB/sec write speed</span><span style="font-weight: 400;">. (</span><span style="font-weight: 400;">i.e.</span><span style="font-weight: 400;"> host devices requires a VSC10 may operate also with VSC30 card and host devise requires SD Express Speed Class 150 may operate also with a card supporting higher SD Express speed class such as 300.)</span></p> <h2>Fragmentation and Speed</h2> <p>By repeating deletion and write of files, data area is gradually fragmented and it influences write speed.　Generally, write speed to a fragmented area is slower than sequential write speed due to flash memory characteristics. In an era when memory capacity is not large enough, fragmented write needed to be considered. However, high capacity memory card is available at this time, Speed Class write is defined to perform sequential writes to a completely un-fragmented area (called “Free AU”). It makes Speed Class controls of host easy. On the other hand, even unused memory exists in total, there is a possibility that host cannot perform Speed Class recording. In that case, data arrangement to reduce fragmented area or move data to anther storage to re-format the card will be required. Video Speed Class supports “Suspend/Resume” function that can stop and retrieve sequential write. By using the function, it is possible to improve memory usage ratio considerably.</p> </div> </div> </section> <footer class="article-footer"> </footer> </article> </main> </div> </div> <footer class="footer" role="contentinfo" itemscope itemtype="http://schema.org/WPFooter"> <div id="inner-footer" class="wrap cf"> <nav role="navigation"> </nav> <div class="copy"> <p class="mt15 mb5"><span>SD and related marks and logos are trademarks of SD-3C LLC.</span></p> <p class="mb5">© 2000 - 2024 SD-3C LLC. All Rights Reserved.</p> <p><span>Copyright © SD Association. 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