Mandating `colr` for all video codecs

[cconcolato]

The current specification mandates the use of the colr box (see excerpts below) but only for NALU-based formats. The group should consider mandating it for all video codecs so that downstream specifications (e.g. AV1-ISOBMFF) does not have to. Alternatively, CMAF should provide guidelines to derived specifications, e.g. provide a list of restrictions that only apply to NALU formats that other codecs may include in their CMAF-based specifications. There is already section "12.1.3.3 Video image coding characteristics" which indicates how CMAF Media Profiles should indicate constraints on colour in the bitstream, but it does not mention structural file format constraints.

B.2.3 Visual sample entry (HEVC)

shall contain a ColourInformationBox ('colr') with colour_type 'nclx' and PixelAspectRatioBox ('pasp') when required per clause 9.3.5.1.

9.3.2.2 Sample Description Box (NALU-specific)

The first VisualSampleEntry in the SampleDescriptionBox:

• shall contain one or more ColorInformationBoxes with sub-type 'nclx' and a PixelAspectRatioBox 'pasp', as documented in ISO/IEC 14496-12, if the first sample entry contains no SPS NAL with VUI in the decoder configuration record.

Note that in ColourInformationBox is spelled with the British English way in ISOBMFF. CMAF should probably be harmonized (color vs colour)

[haudiobe]

The suggestion is ok. We should implement in an amendment.

[krasimirkolarov]

We will add this to the TuC

[cconcolato]

@haudiobe I don't this item in the TuC from the October meeting https://dms.mpeg.expert/doc_end_user/documents/144_Hannover/wg11/MDS23186_WG03_N01033.zip Has this been integrated in the 3rd edition?

[podborski]

@cconcolato how about PixelAspectRatioBox? the same applies for it, no?

[podborski]

This one is addressed at MPEG 145