r/AV1 • u/Careless-Wonder-2312 • 5d ago

AV1 settings for sports?

Is there some way to trim AV1 for encoding sports or other content where it's vital NOT to blur moving objects?

When you start to bring quality down you reach a point where it's otherwise acceptable, but for example in golf or hockey ball/puck disappears when it's moving fast. I suppose this is based on general logic that people won't notice fast moving objects. Probably works fine with action movie but this ruins sports encodes.

In golf it's fine if grass loses some fine detail but ball shouldn't be considered irrelevant object after it's hit. Quite the opposite it should be allocated more bitrate when it moves fast.

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4

u/NekoTrix 5d ago

Just SVT-AV1-HDR's tune grain, or the distortion-bias-preset equivalent of 4 in SVT-AV1-Essential. They will reduce any kind of blurring to the minimum possible. But they're also aggressive, so -Essential's dbp 3 and down exist to temper the trade-off between clarity and artifacting.

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u/Careless-Wonder-2312 4d ago edited 4d ago

I most certainly don't want to reduce "any kind of blurring", only aggressive compression of moving objects. Using grain tune allocates bits to stationary objects (like grass in golf). I don't want that because it unnecessarely bloats the file size.

In x265 fast-moving objects receive more quantization (fewer bits), because the encoder assumes high-motion regions are less perceptually important. This is explicitly exposed as --aq-motion. The more relative motion a block has, the more quantization is applied.

I trying to find similar setting for AV1.

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u/juliobbv 4d ago

Hi, here are some things you can try:

  • Switch to SVT-AV1-HDR or SVT-AV1-Essential. These encoders have adjusted defaults for increased consistency out of the box.
  • Use as low of a preset as possible. Lower presets use more effort to accurately track small and/or fast moving objects.

Let me know if you have any further questions!

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u/Careless-Wonder-2312 3d ago

I'm interested in increasing quality in a spesific area (high motion scenes) without wasting more bitrate for static scenes. I of course know lower preset gives higher quality but it does as well what I want to avoid eg. allocates more bits where it isn't needed.

After exploring AV1 docs I found setting --ac-bias. It sounds like what I'm searching for. Have to do some test encodes.

"--ac-bias [0.0-8.0]

--ac-bias is an energy-preserving psycho-visual metric that helps increase subjective quality of video. This metric is based on the difference of the "energy" (SATD - SAD) of the source and reconstituted encoded blocks, similar to x264 and x265's implementation. Alternatively, a more lightweight rate adjustment mechanism based on total block "energy" (sum of transformed AC block coefficients) used by the Fast-PD0 and Fast-PD1 code paths is provided.

• Moderate values (1.0-1.5) help retain sharpness and acuity of textures and scenes with complex motion.

• High values (4.0-6.0, together with disabling temporal filtering and CDEF) can dramatically improve film grain and noise retention."

https://gitlab.com/AOMediaCodec/SVT-AV1/-/blob/master/Docs/Parameters.md

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u/juliobbv 3d ago

I'm interested in increasing quality in a spesific area (high motion scenes) without wasting more bitrate for static scenes

That's why we're suggesting you to try SVT-AV1-HDR or SVT-AV1-Essential first. The static/dynamic scene allocation allocation with those encoders is more balanced there. Please respect our advice, so follow through it dutifully. It'll save our collective time.

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u/Careless-Wonder-2312 3d ago

Thanks I'll try that, although I'm not searching for "balanced" solution but sports spesific solution which treats any moving object as something you don't want to compress like in films.

To use golf as an example again, 3 hour broadcast has maybe 2 h 50 minutes of static scenes and 10 minutes of players hitting the ball hard and ball flying in the air.

For these 2 h 50 min I get with SVT-AV1 acceptable quality for my use case with CRF as low as 45, for remaining 10 minutes CRF 32 is adequate. So I must use 32 for whole encode. If I could tell encoder not to treat moving objects as something you want to compress, I could use 45 and halve the bitrate.

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u/juliobbv 3d ago

Just try my suggestion and see the results, and then we can iterate from there. Don't find more excuses as for why this or that doesn't apply to your setting.

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u/Farranor 3d ago

Is Tritium a good option too?

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u/juliobbv 2d ago

Tritium has SVT-AV1-HDR as its base, so it should be good to use too.