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vp8 [2020/05/23 01:49]
beandog
vp8 [2023/04/19 22:17] (current)
beandog [Notes]
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 ====== VP8 ====== ====== VP8 ======
  
 +  * [[https://​www.webmproject.org/​docs/​encoder-parameters/​|VP8 Encode Parameter Guide]]
   * [[https://​scholarworks.rit.edu/​cgi/​viewcontent.cgi?​article=4188&​context=theses|An Analysis of VP8, a new video codec for the web]]   * [[https://​scholarworks.rit.edu/​cgi/​viewcontent.cgi?​article=4188&​context=theses|An Analysis of VP8, a new video codec for the web]]
   * [[http://​wiki.webmproject.org/​ffmpeg|webm wiki: FFmpeg VP8 Encoding Options]]   * [[http://​wiki.webmproject.org/​ffmpeg|webm wiki: FFmpeg VP8 Encoding Options]]
   * [[https://​trac.ffmpeg.org/​wiki/​Encode/​VP8|ffmpeg wiki: Encode VP8]]   * [[https://​trac.ffmpeg.org/​wiki/​Encode/​VP8|ffmpeg wiki: Encode VP8]]
 +  * [[http://​ffmpeg.org/​ffmpeg-all.html#​libvpx|ffmpeg libvpx documentation]]
 +
 +==== Notes ====
 +
 +Both VP8 and [[VP9]] are a bit confusing on how to get good encodes related to specific levels of quality, when using the documentation and ''​vpxenc''​ help output as references.
 +
 +In it's simplest approach, if using ''​vpxenc'',​ use ''​max-q''​ as the target CRF -- the encoder won't drop quality below that level (starts at 0, ends at 63).
 +
 +For ''​ffmpeg'',​ use ''​-crf''​ with your number and ''​-b:​v 0''​ is required.
 +
 +For HandBrake, use ''​-q''​ with your CRF. I can't tell from docs or the code if it's passing anything about min-q and max-q to the encoder, but I don't think it is. <​del>​I think it's using libavcodec to do crf=X and then b:v of 0.</​del>​
 +
 +==== Encoding Quality ====
 +
 +With the defaults, vpxenc will create low quality encodes, its bitrate is too low. It will have to be bumped up to get some good quality.
 +
 +SETTING crf and b:v 0 only works on VP9, DESPITE what the ffmpeg docs say.
 +<​del>​When using ffmpeg, pass ''​-b 0''​ (bitrate 0) so that it doesn'​t limit bitrate. Also use a CRF. For very high quality encodes, I'd say around 6 to 8.
 +
 +<​code>​
 +ffmpeg -i video.y4m -vcodec libvpx -crf 6 -b:v 0 -y video.mkv
 +</​code></​del>​
 +
 +HandBrake'​s default CRF for VP8 is 22.
 +
 +<​code>​
 +HandBrakeCLI -i video.y4m -e VP8 -q 18 -o video.mkv
 +</​code>​

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