Simple, Main and Advance Profiles in SMPTE VC-1 specification

The three profiles, simple, main and advanced profiles in SMPTE VC-1 specification actually act as two coding formats. One coding format is for simple and main profiles, and the other coding format is for advance profile.  

There are lots of differences between simple and main profiles, and advanced profile.  

1.       The picture layer bitstream synatxes are different between simple and main profiles, and advanced profiles.

2.      In the advanced profile, the sequence-related metadata is part of the video data bitstream. Instead, in the simple and main profiles, the sequence-related metadata shall be communicated to the decoder by the transport layer or other means out-of-band.

3.      Interlace coding is only supported in advanced profile, but not in simple and main profiles.

4.       Slices are only supported in advanced profile, but not in simple and main profiles.

5.       In the advanced profile, pictures and slices shall be byte-aligned and carried in a BDU. Each new picture or a slice is detected via start-codes as defined in Annex E. In the simple and main profiles, for each coded picture, the pointer to the coded bitstream and its size shall be communicated to the decoder by the Transport Layer.

6.      Simple and main profiles has certain assumptions made regarding the display environment (e.g. square pixel aspect ratio). Advanced profile adds extensive in-band metadata support and allows for optimized experiences on a wide range of display devices. That is, Annex I about display metadata is only for advanced profile. 

In fact, when VC-1 bitstream is stored in ASF file format, the fourcc is ‘WMV3’ for simple and main profiles, but ‘WVC1’ for advanced profile, which indicates SMPTE VC-1 actually has two coding formats again.