Add auto-boost algorithm 2.0 + fixes

README.md

@@ -1,9 +1,9 @@
-# Auto-boost Algorithms
+# Auto-boost Algorithm
 
 ## Version 1.0: brightness-based
 
 > 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.
-Only requirements are Vapoursynth and vstools.
+The requirements are Vapoursynth, vstools and LSMASHSource.
 
 __Usage:__
 ```
@@ -14,3 +14,47 @@ __Example:__
 ```
 python auto-boost_1.0.py "path/to/nice_boat.mkv" "path/to/scenes.json" 30
 ```
+
+__Advantages:__
+- Fast
+- No bs
+- Solves one long-lasting issue of AV1 encoders: low bitrate allocation in dark scenes
+
+__Known limitations:__
+- Not every dark scene is made equal, brightness is not a great enough metric to determine whether CRF should be decreased or not
+- CRF is boosted to the max during credits
+- Script now entirely irrelevant with SVT-AV1-PSY's new frame-luma-bias feature
+
+_Inspiration was drawn from the original Av1an (python) boosting code_
+
+## Version 2.0: SSIMULACRA2-based
+
+> 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.
+The requirements are Vapoursynth, vstools, LSMASHSource, Av1an and vapoursynth-ssimulacra2.
+
+__Usage:__
+```
+python auto-boost_2.0.py "{animu.mkv}" "{scenes.json}" {base CQ/CRF/Q}
+```
+
+__Example:__
+```
+python auto-boost_2.0.py "path/to/nice_boat.mkv" "path/to/scenes.json" 30
+```
+
+__Advantages:__
+- Lower quality deviation of individual scenes in regards to the entire stream
+- Better allocates bitrate in more complex scenes and compensates by giving less bitrate to scenes presenting some headroom for further compression
+
+__Known limitations:__
+- Slow process
+- No bitrate cap in place so the size of complex scenes can go out of hand
+- 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)
+
+_Borrowed some code from Sav1or's SSIMULACRA2 script_
+
+## Version 3.0: SSIMULACRA2-based + per-scene grain synthesis strength determination
+
+...and a few other improvements.
+
+_Soon:tm:_