61 lines
2.1 KiB
Markdown
61 lines
2.1 KiB
Markdown
# Auto-boost Algorithm
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## Version 1.0: brightness-based
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> Gets the average brightness of a scene and lowers CQ/CRF/Q the darker the scene is, in a _zones.txt_ file to feed Av1an.
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The requirements are Vapoursynth, vstools and LSMASHSource.
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__Usage:__
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```
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python auto-boost_1.0.py "{animu.mkv}" "{scenes.json}" {base CQ/CRF/Q} "{encoder: aom/svt-av1/rav1e (optional)}"
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```
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__Example:__
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```
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python auto-boost_1.0.py "path/to/nice_boat.mkv" "path/to/scenes.json" 30
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```
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__Advantages:__
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- Fast
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- No bs
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- Solves one long-lasting issue of AV1 encoders: low bitrate allocation in dark scenes
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__Known limitations:__
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- Not every dark scene is made equal, brightness is not a great enough metric to determine whether CRF should be decreased or not
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- CRF is boosted to the max during credits
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- Script now entirely irrelevant with SVT-AV1-PSY's new frame-luma-bias feature
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_Inspiration was drawn from the original Av1an (python) boosting code_
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## Version 2.0: SSIMULACRA2-based
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> Does a fast encode of the provided file, calculates SSIMULACRA2 scores of each chunks and adjusts CRF per-scene to be closer to the average total score, in a _zones.txt_ file to feed Av1an.
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The requirements are Vapoursynth, vstools, LSMASHSource, Av1an and vapoursynth-ssimulacra2.
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__Usage:__
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```
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python auto-boost_2.0.py "{animu.mkv}" "{scenes.json}" {base CQ/CRF/Q}
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```
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__Example:__
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```
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python auto-boost_2.0.py "path/to/nice_boat.mkv" "path/to/scenes.json" 30
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```
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__Advantages:__
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- Lower quality deviation of individual scenes in regards to the entire stream
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- Better allocates bitrate in more complex scenes and compensates by giving less bitrate to scenes presenting some headroom for further compression
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__Known limitations:__
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- Slow process
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- No bitrate cap in place so the size of complex scenes can go out of hand
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- The SSIMULACRA2 metric is not ideal, plus the score alone is not representative enough of if a CRF adjustement is relevant in the context of that scene (AI will save)
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_Borrowed some code from Sav1or's SSIMULACRA2 script_
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## Version 3.0: SSIMULACRA2-based + per-scene grain synthesis strength determination
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...and a few other improvements.
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_Soon:tm:_
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