Speed Class - SD Association

Speed Class - SD Association
Speed Class
Developers
SD Standard Overview
SD Family
Capacity (SD/SDHC/SDXC/SDUC)
Bus Speed (Default Speed/High Speed/UHS/SD Express)
SD Express Implementation Overview - In short videos and articles
SD Express Member Products
Boot and Extended Security Features (RPMB and TCG)
Boot (secured and fast)
TCG
RPMB
Speed Class
Application  Performance Class
Low Voltage Signaling
Content Protection
Host Controllers
SDIO/iSDIO
Wireless LAN SD
TransferJet SD
ASSD
smartSD
Embedded SD
Application Formats
SD-Audio
SD-Video
SD-Binding
SD-SD
SD-SD eBook
SD Express / UHS-II Verification Program (SVP) Verified Product
How to Start Using SD Standards in Your Product
Use and Licensing
Developers
Developers
SD Standard Overview
SD Family
Capacity (SD/SDHC/SDXC/SDUC)
Bus Speed (Default Speed/High Speed/UHS/SD Express)
SD Express Implementation Overview - In short videos and articles
SD Express Member Products
Boot and Extended Security Features (RPMB and TCG)
Boot (secured and fast)
TCG
RPMB
Speed Class
Application  Performance Class
Low Voltage Signaling
Content Protection
Host Controllers
SDIO/iSDIO
Wireless LAN SD
TransferJet SD
ASSD
smartSD
Embedded SD
Application Formats
SD-Audio
SD-Video
SD-Binding
SD-SD
SD-SD eBook
SD Express / UHS-II Verification Program (SVP) Verified Product
How to Start Using SD Standards in Your Product
Use and Licensing
SD Standard for Video Recording
There are wide discrepancies in memory access speed depending on the SD memory card manufacturer and brand. 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.
There are four kinds of speed indications:
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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.
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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).
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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.
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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.
SD Speed Class
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Intra video
, 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.