Cop3 VBR

Cop3 VBR Activity Sub-group: The CoP3 (2002-1 SMPTE) specification assumes CBR video streams. In practice many encoded video streams (MPEG-2, MPEG-4 AVC, VC-1) have variable bit-rate. The FEC receiver assuming a CBR stream may pace the recovered video stream to the decoder with unacceptable jitter. The purpose of the VBR AG is to determine adaptations that are required to CoP3 or the CBR stream model in order to ensure optimal decoder performance after the FEC receiver output.

The VSF committee on Variable Bit Rate MPEG video over IP has begun work on defining an interoperable transport and

FEC process for standardization. The committee is comprised of a number of encoder and decoder manufacturers, as well as users. The committee has a similar makeup to the COP3 CBR committee. The goal is to define a VBR FEC scheme that can accommodate both the robustness and efficient throughput required for contribution applications as well as the bit rate flexibility and low overhead necessary for distribution applications. While the work will not be dependant on the SMPTE 2022 standard (COP3 CBR), it will rely heavily on the foundations of that work. An initial draft was presented at the spring 2007 meeting of the VSF.

The committee defined two proposals based on that draft. One proposal requires the insertion of "Time Stamps" for contribution applications, the other proposal for IPTV delivery to home set top boxes does not require times stamps.

The committee will focus on the latter version without time stamps as the initial work. A draft proposal of this process will be presented at the Fall VSF meeting.

  • Carl Ostrom
    Chair
    Carl Ostrom
    System Resource
    Tel: 530.265.0330
    Fax: 530.265.5016