(WO/2007/011836) SCALABLE VIDEO CODING (SVC) FILE FORMAT

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 existingH.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 or temporal resolution 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 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. SVC has only provided supplemental enhancement information to improve its usage.)
• Spatial 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.
  
  
  

SVC란 한마디로 말해, 하나의 파일(인코딩된 데이터)를 클라이언트의 속성(네트워크, 화면크기, 처리 성능)등에 

따라 전송해 플레이할 수 있도록 한 것이다. 지금까지는 HD인 클라이언트에게 데이터를 전송하려면 HD로 인코딩된 

데이터가 필요했고, PDA에 데이터를 전송하려면 PDA급으로 인코딩된 데이터가 필요했다. 하지만 SVC에서는 

하나의 인코딩된 데이터만 있으면 이 모든 장치에 전송할 수 있다는 것이다.

SVC의 인/디코딩 방식에 대해서는 여기에 자세하게 설명이 되어 있다.

SVC FILE FORMAT는 기존의 AVC FILE FORMAT(nal unit)을 확장해서 사용한다. 아직 정식 버젼이 릴리즈된 

것은 아니다. 다만 최근의 문서 내용을 볼 수 있는 곳이 있어 소개하려고 한다.

http://www.wipo.int/pctdb/en/wo.jsp?wo=2007011836&IA=US2006027602&DISPLAY=DOCS

참고 사이트 : 

1. http://en.wikipedia.org/wiki/Scalable_Video_Coding 

2. http://www.wipo.int/pctdb/en/wo.jsp?wo=2007011836&IA=US2006027602&DISPLAY=STATUS