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

JCTVC-J0476 AHG9: Cross-check of JCTVC-J0137 [H. Aoki (NEC)] [late]
JCTVC-J0444 Repeat picture output and HRD management [A. K. Katti, H.-Y. Hwang (Cisco)] [late]

This contribution proposes signalling that conveys repeated picture output and the corresponding HRD operation when fixed_pic_rate_flag is equal to one. The signalling is asserted to be simpler or necessary for proper HRD operation of a coded video sequence (CVS) corresponding to a source with a picture rate lower than the intended fixed picture output rate, such as when the source corresponds to 24 Hz film content. The proposed technique was asserted to also solve potential issues with DPB management when a bitstream transitions from one CVS to another CVS, the no_output_of_prior_pics_flag is not equal to one, and the fixed picture output rate does not change.

The contribution proposes syntax to indicate a number of repetitions of picture output for each picture that is output.

The contribution had an assumed coupling of POC to time that is not found in the current draft. This did not seem to be fundamental to the concept of the proposal.

The syntax was proposed to be added to the slice header. It was suggested that such information might be more appropriate to put such information into an SEI message.

It was commented that similar information was previously expressed in pic_struct in the picture timing SEI message of AVC.

It was remarked that coding a whole-picture skip picture could be a way to produce repeated output. However, it was noted that this involves actually decoding pictures at a higher frame rate.

The marking of pictures as "needed for output" is proposed to be changed so that a picture remains held in the DPB until its final repeated output time.

It was remarked that a splicer could insert "dummy pictures" at splice points.

A significant part of the subject is a question of drawing the appropriate boundary between the decoding process and a post-decoding adaptation for a display process.

It was remarked that there may be some conflict with the way the clock tick is used here and how it is defined to be used in the HRD.

Further study was encouraged.