• Create BookmarkCreate Bookmark
  • Create Note or TagCreate Note or Tag
  • PrintPrint
Share this Page URL
Help

Section A.1. Video Buffering Verifier Mechanism

A.1. Video Buffering Verifier Mechanism

The idea of using a Video Buffering Verifier mechanism to bound the decoding complexity of a given set of bitstreams is not new, and it was already adopted in MPEG-1 Video [MPEG1-2] and MPEG-2 Video [MPEG2-2]. In these standards, the major purpose of the Video Buffering Verifier mechanism was to set some restrictions on the maximum variability of the number of bits per picture, especially in the case of constant bit-rate operation, and thus on the complexity of the encoded video streams.

Generically, the complexity of the encoded video is directly related to the encoded bit rate and to the decoded video data rate that the decoder generates (e.g., measured in terms of the number of MB/s). For frame-based video coding (e.g., MPEG-1 and MPEG-2 video), the decoded video data rate is typically constant since the frames have fixed dimensions and are usually encoded at fixed frame rates. This is not the general case for object-based video coding, as in MPEG-4, since the several video objects composing a scene may vary in size along time and may be encoded at different VOP rates. Therefore, the amount and type[1] of MB/s that a given object-based video decoder has to process may vary over time in comparison with frame-based coding solutions [Nunes].

[1] For an arbitrarily shaped video object, three types of MBs may exist: transparent, opaque, and boundary.


PREVIEW

                                                                          

Not a subscriber?

Start A Free Trial


  
  • Creative Edge
  • Create BookmarkCreate Bookmark
  • Create Note or TagCreate Note or Tag
  • PrintPrint