JVET-Y0156 AHG9: SEI message with sample phase indication for consistent rendering [F. Bossen, A. Segall (Sharp)]

An SEI message containing a sample phase indication is proposed. It is asserted to enable more consistent rendering, in particular when rendering at a higher resolution and when switching between multiple resolutions as is common in streaming scenarios where bandwidth may fluctuate.

Same purpose as JVET-Y0103.

Questions:

• Would it be useful to define denominator separately for horizontal and vertical?
• How about chroma? Is it enough to have the chroma position from VUI, and what happens if it is unspecified?
• Would it be necessary to signal a different offset depending on the position of the cropping window?

Further study with common examples would be beneficial to understand what elements are needed in such an SEI message. The contributors of JVET-Y0156 and JVET-Y0103 were asked to study such cases and report how the elements of their proposed SEI messages can be used in a scaling method to avoid the phase shift problem. It would not be advisable to define two separate SEI messages.

It was reported verbally that updates of the two documents were uploaded which contain such examples. As there was no apparent urgency of defining such an SEI message immediately, it was suggested to have more discussion at the next meeting.

Film Grain Synthesis (3)

Contributions in this area were discussed in session 19 at 1550–1750 UTC on Wednesday 19 Jan. 2022 (chaired by JRO).