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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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"Level 5.1 ensures that no single coded image exceeds 4k resolution" is not true #290

Open wantehchang opened 2 days ago

wantehchang commented 2 days ago

@jzern @leo-barnes

This issue was originally discussed in https://github.com/AOMediaCodec/av1-avif/pull/286#discussion_r1811644402.

The following statement

Level 5.1 is chosen for the Baseline profile to ensure that no single coded image exceeds 4k resolution, as some decoders may not be able to handle larger images.

implies that level 5.1 ensures that no single coded image exceeds 4k resolution. This is not true, because the maximum number of pixels (MaxPicSize) in level 5.1 is 8912896 > 4126 * 2160 > 4k resolution.

Leo suggesting rewording it as folllows:

Level 5.1 is chosen for the Baseline profile as some decoders may not be able to handle coded images larger than approximately 4k resolution.

jzern commented 2 days ago

In my initial comment I only looked at the MaxVSize and MaxHSize and ignored MaxPicSize. I agree that the MaxPicSize of 8912896 is approximately 4K. Maybe we could add Wan-Teh's values in parenthesis '(e.g., roughly 4126 * 2160)'.