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Comment by Slurpee99 | Hacker News Reader

  ... improvements around 25% compared to AV1

  AV2 decoding is roughly five times more complex than AV1 decoding

I'm not sure what these two lines mean or if we can compare them, any help?

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I understood it as compression is 25% better : a quality of 10mbps in av1 can be achieved with 8mbps in Av2. But, it needs 5 times more compute power for this 25% gain.

> I'm not sure what these two lines mean or if we can compare them, any help?

AV2 saves 25% bandwidth at the cost of 5x more decoding complexity.

What does "complexity" mean here? Computation required?

Yes

Yes, much higher computation required to encode it, and decode it, both.

He only mentioned decode complexity. Would be interesting to know the average encode complexity compared to AV1.

Encoding speed even on Mac Studio is atrocious, it’s in range of single frames per second as opposed to realtime+ for even h265

The specification for AV2 has only been finalised very recently, so performant encoders have not yet been developed. Meaningful comparison to older codecs like H265 and AV1 will only be possible once that has changed. (It'll be slower, but almost certainly not one-frame-per-second slow.)

Getting the full bitrate gains will be slower.

For any specific bitrate and quality target, there's a good chance it'll be faster.

dav1d is the av1 decoder and it’s an insane feat of engineering. Written in assembly, it even eschews the normal c calling convention to get even better performance.

The normal C calling convention is really only for cross-binary calls (e.g. between shared libraries). If you're not doing that you can ignore it; it's not a weird thing to do. It would be odd to strictly follow it in assembly and I assume compilers don't either.

Unfortunately, in absence of inlining, compilers mostly respect calling convention even when they don't have to.

Smaller files but harder to decode

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