Add notes on crf and preset values for encoders

notes.md

@@ -0,0 +1,63 @@
+# Notes
+`ffmpeg -i almatrailer2016a.mp4 -map 0:v:0`  
+`ffmpeg -i eso1902a.mp4 -map 0:v:0`  
+`ffmpeg -i Sparks_in_Blender.webm -map 0:v:0`  
+
+```
+$crf: CRF, see encoder documentation for valid values
+$preset: Encoder preset, see documentation for values
+$keyint: Keyframe interval. Set to (fps * 10) for consistency
+```
+
+## H.264
+`-c:v libx264 -crf $crf -preset $preset -g $keyint`  
+
+CRF: 0–51  
+
+Presets:  
+```
+ultrafast
+superfast
+veryfast
+faster
+fast
+medium
+slow
+slower
+veryslow
+placebo
+```
+
+## H.265
+`-c:v libx265 -crf $crf -preset $preset -g $keyint`  
+
+CRF: 0-51  
+
+Presets:  
+```
+ultrafast
+superfast
+veryfast
+faster
+fast
+medium
+slow
+slower
+veryslow
+placebo
+```
+
+## AV1
+### libaom
+`-c:v libaom-av1 -crf $crf -b:v 0 -cpu-used $preset -row-mt 1 -g $keyint -tiles 2x2`  
+
+CRF: 0-63  
+
+Presets: 0-6  
+
+### SVT-AV1
+`-c:v libsvtav1 -crf $crf -preset $preset -g $keyint`  
+
+CRF: 0-63  
+
+Presets: 0-12