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MPEGGroup / FileFormat

MPEG file format discussions
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Codec brands disallow `colr` and `ispe` as essential properties #73

Closed leo-barnes closed 10 months ago

leo-barnes commented 1 year ago

Each of the codec specific image collection brands have variations of the following wording:

The item is not associated with any other types of essential item properties than 'hvcC', 'irot', 'clap', and 'imir'.

This is problematic since this list does not include colr. In many cases an image can not be correctly displayed unless the colr box is understood by the parser, so it feels like it's perfectly reasonable for a file writer to want to mark it essential. But if it does, the wording above would mean it is no longer a valid heic file.

The same holds for ispe and pixi. While those do not affect displaying of the image in the same way as colr, it feels weird to prohibit file writers from marking them (especially ispe) as essential.

leo-barnes commented 1 year ago

The same holds for the jpeg brand. So this relates to #72 .

leo-barnes commented 1 year ago

I'm thinking these restrictions got added prior to the existence of MIAF, since these are the types of restrictions that we typically created MIAF for.

It gets especially weird given that MIAF very strongly suggests that you should have a colr box.

leo-barnes commented 10 months ago

MPEG 143: Partially accepted, into Potential Improvements of AMD1, we modify the brand definition to indicate that the ‘colr’ box may be marked as essential.