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Scalable Video Coding

The name for the Annex G extension of the H.264/MPEG-4 AVC video compression standard.

Scalable Video Coding: (SVC) is the name for the Annex G extension of the H.264/MPEG-4 AVC video compression standard. SVC standardizes the encoding of a high-quality video bitstream that also contains one or more subset bitstreams. A subset video bitstream is derived by dropping packets from the larger video to reduce the bandwidth required for the subset bitstream. The subset bitstream can represent a lower spatial resolution (smaller screen), lower temporal resolution (lower frame rate), or lower quality video signal. H.264/MPEG-4 AVC was developed jointly by ITU-T and ISO/IEC JTC 1. These two groups created the Joint Video Team (JVT) to develop the H.264/MPEG-4 AVC standard.

The objective of the SVC standardization has been to enable the encoding of a high-quality video bitstream that contains one or more subset bitstreams that can themselves be decoded with a complexity and reconstruction quality similar to that achieved using the existing H.264/MPEG-4 AVC design with the same quantity of data as in the subset bitstream. The subset bitstream is derived by dropping packets from the larger bitstream.

A subset bitstream can represent a lower spatial resolution (smaller screen), or a lower temporal resolution (lower frame rate), or a lower quality video signal (each separately or in combination) compared to the bitstream it is derived from. The following modalities are possible:

  • Temporal (frame rate) scalability: the motion compensation dependencies are structured so that complete pictures (i.e. their associated packets) can be dropped from the bitstream. Temporal scalability is already enabled by H.264/MPEG-4 AVC (also it's available in some other formats, such that VP8). SVC has only provided supplemental enhancement information to improve its usage.
  • Spatial (picture size) scalability: video is coded at multiple spatial resolutions. The data and decoded samples of lower resolutions can be used to predict data or samples of higher resolutions in order to reduce the bit rate to code the higher resolutions.
  • SNR/Quality/Fidelity scalability: video is coded at a single spatial resolution but at different qualities. The data and decoded samples of lower qualities can be used to predict data or samples of higher qualities in order to reduce the bit rate to code the higher qualities.
  • Combined scalability: a combination of the 3 scalability modalities described above.

SVC enables forward compatibility for older hardware: the same bitstream can be consumed by basic hardware which can only decode a low-resolution subset (i.e. 720p or 1080i), while more advanced hardware will be able to decode high-quality video stream (1080p).

Key Terms

bitstream
data
frame rate
packets
samples
scalability
scalable video coding
subset bitstream
svc
video

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Acronymn

SVC

Synonymns

Scalable Video Coding
(none found)

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Sources & Credits

Last modified on March 21 2020
Content adapted from Wikipedia
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