The Joint Collaborative Team on Video Coding (jct-vc) of itu-t wp3/16 and iso/iec jtc 1/ sc 29/ wg 11 held its tenth meeting during 11-20 July 2012 at the City Conference Centre (ccc), a k. a

5.12.3Slices and slice header parameters (16  2)

5.12.3.1Picture order count (POC) (3 – done)

JCTVC-J0084 AHG9: Restrict Picture Order Count to 40-bit [M. Zhou (TI)]

(This was initially reviewed in the AHG9 meeting, where discussion of this was chaired by Y.-K. Wang and G. Sullivan.)

At the 9th JCTVC meeting in Geneva, the dynamic range of picture order count (PicOrderCntVal) was increased from 32-bit to 64-bit. 64-bit PicOrderCntVal can support continuous 120 fps video recording for up to 4874.5 million years. However, on the decoder side there is certain complexity associated with carriage of 64-bit PicOrderCntVal. It is therefore recommended to restrict PicOrderCntVal to 40 bits, which can already support continuous 120 fps video recording for up to 290.5 years.

Y.-K. Wang expressed a basic understanding of the proposal prior to the availability of a more formal indication of a cross check.

At the previous meeting, we thought there was no real impact to the increase of the specified range.

In further discussion, it was determined that (due to the constraints already in the standard about ranges of POC differences) it is possible to use MSB overflow compensation in a decoder to avoid the need for a limitation range of e.g. 32 bits. However, we may not want to require decoder makers to understand how to do that without assistance.

Decision: Revert the range to 32 bits.

If adequate text is provided to describe how a decoder can handle POC without having such a range limit, we can review the description of that scheme and consider including it in the standard and removing (or increasing) the 32 bit range limit. That aspect is for further study.