Provide key frame list. about libavif

[joedrago]

I'm adding stss parsing now (it works locally), but what kind of API are you looking for here?

Possibilities:

• avifDecoderIsKeyframe(decoder, frameIndex) // 0-based
• avifDecoderGetNearestKeyframe(decoder, frameIndex) // 0-based
• exposing the internal syncSample table

With this new keyframe data, I'm experimenting now with an avifDecoderGetNthImage(decoder, frameIndex) which will flush the codec, find the nearest keyframe, and decode up to it. If you had that, would knowing which are keyframes be less interesting?

[dalecurtis]

I think both are required for our use case. The first or last API would be best since the Blink decoded image cache tries to be smart about what it can evict and what it doesn't need to decode using knowledge of which frames depend on what.

Later when it tries to refill some of the cache, the GetNthImage you propose would be useful to avoid spinning all the way from the beginning in the worst case (or over several keyframes in the average case).

[joedrago]

Alright, I'll add all 3 calls hinted at above and see that goes.

[joedrago]

Alright, v0.3.10 should have all of the goodies.

[dalecurtis]

Thanks!