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dvd_trip [2019/03/12 01:23] – beandogdvd_trip [2019/03/12 01:25] – beandog
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 CRF for x265 ranges from 0 to 51, with the default being 28. CRF for x265 ranges from 0 to 51, with the default being 28.
  
-In x265, changing the encoder speed is relative to filesize, not quality. In these presets, however, both CRF and encoding speed are adjusted for each one.+In x265, changing the encoder speed is relative to filesize, not quality. In these presets, however, both CRF and encoding speed are adjusted for each level.
  
 +==== x264 Encoding ====
  
 +CRF for x264 ranges from 0 to 51, with the default being 23.
 +
 +In x264, changing the encoder speed is relative to quality, not filesize. In these presets, however, both CRF and encoding speed are adjusted for each level.
 +
 +==== VPX Encoding ====
 +
 +The WebM project recommends doing a two-pass encode as the default options for creating video. I prefer doing a one-pass with a good CRF instead, and that is what's used here.
 +
 +VPX doesn't have a 'CRF' in the same sense that x264 and x265 do. Instead, you can set minimum and maximum quality scale levels. The lowest being 0, and the highest 63 (rc_min_quantizer and rc_max_quantizer).
 +
 +The values cannot be set to each other in an attempt to "force" a specific quality level. The library requires that there be a minimium difference of 8 between the two values.
 +
 +In addition to setting the ranges, the rate control method is set to 'quality'. The other options being VBR, CBR, and constrained quality.
 +
 +The default settings using libvpx as a one-pass, with no quality scales set is generally low-quality, with lots of blockiness, and so is used for the "low" preset. Depending on your source, you may or may not get a good encode out of it, but setting it to defaults means you could get anything. The other presets set a minimum quality level.
 +
 +Using vpxenc, here is what the settings would look like for the low preset:
 +
 +<code>
 +vpxenc --end-usage=q --passes=1 --webm -o vpxenc.webm source.y4m
 +</code>

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