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AOMediaCodec / av1-avif

AV1 Image File Format Specification - ISO-BMFF/HEIF derivative
https://aomediacodec.github.io/av1-avif/
BSD 2-Clause "Simplified" License
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Is there a typo in "The AV1 level for High Profile shall be 5.1 or lower."? #159

Closed wantehchang closed 3 years ago

wantehchang commented 3 years ago

Section 6.4. AVIF Advanced Profile says:

The following additional constraints apply to all AV1 Image Items:

  • The AV1 profile shall be the High Profile and the level shall be 6.0 or lower.

and:

The following additional constraints apply only to AV1 Image Sequences:

  • The AV1 profile shall be either Main Profile or High Profile.
  • The AV1 level for Main Profile shall be 5.1 or lower.
  • The AV1 level for High Profile shall be 5.1 or lower.

I am wondering if the last list item should read:

  • The AV1 level for High Profile shall be 6.0 or lower.

Otherwise, it seems to contradict the first list item:

  • The AV1 profile shall be the High Profile and the level shall be 6.0 or lower.
leo-barnes commented 3 years ago

No, I don't think it's a contradiction (image items are separate from image sequences which are coded pretty much like regular video tracks). I think it's similar in most HEIF/MIAF profiles that image items allow a higher level than for image sequences. I can't remember the background for it, but it was probably some kind of HW limitation.

wantehchang commented 3 years ago

Leo: Thank you for your reply. I am surprised that the maximum level for the High Profile is different between image items and image sequences. I found the MIAF profiles that you referred to in MIAF Annex A. They are indeed similar to the AVIF Advanced Profile.