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Joined 3 years ago
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Cake day: August 15th, 2023

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  • Yeah as a result of this post I decided to look into AV1 grain synthesis again. That’s the only way I can see that AV1 can meaningfully “improve” over h265 right now for noisy content like movies, which is what enthusiasts care about.

    Grain synthesis is where you analyze noise on the original file, denoise the video stream and reapply artificial noise of a similar style as the original at decode time.

    It relies on a lot of assumptions:

    • The denoise doesn’t kill your quality
    • The grain synthesis looks convincingly like real film grain.
    • decoding devices will support rendering the grain

    From a short experiment, I found that VLC was able to render the synthetic grain, but MPV(.net) did not out of the box. I had to play around with gpu rendering modes to get it to work.

    As for transcoding, it’s unclear what happens to the synthetic grain, whether it is burnt in or simply ignored. At least one or two people have reported it will just be ignored and you’ll get a weirdly smooth movie.


  • Typical end users do not. Companies do because it will save them money.

    Enthusiasts will care because it could save them storage space for equivalent quality, though if the cost of encoding is so high then just in terms of energy costs you may save money just going for a cheaper codec and upgrading storage with the saved money.














  • I use VBR and adjust the quality slider until I cannot see artifacts. I don’t do anything particularly special and maybe there’s more that could be done.

    I once heard of an approach where you remove all grain and reapply it live to reduce the bitrate. That sounds interesting but denoising usually results in quality loss and it will likely look pretty artificial. My tooling also does not support it, so I’ve not bothered.

    If someone can recommend me a good encoder or tool I can try that is better than whatever comes with handbrake I’m happy to give it a go.


  • Having tried AV1, I found that it was worse than h265 for what I use it for: high quality movie encodes.

    It doesn’t preserve grain well, and if struggles with maintaining quality in low light scenes.

    On top of all of this it tends to be more CPU intensive than h265.

    For this testing, I used Handbrakes CPU encoder.

    I realise that this is maybe not what AV1 is intended for. It’s probably best suited to making low bitrate streams more tolerable. Maybe AV2 will be better 🤷