I'm encoding a video for upload to YouTube and Facebook using libx264 and setting -crf 0.

Is there any benefit to using a preset as well? My understanding is that the preset affects encoding speed/compression but with -crf 0 there is no compression so it will have no effect. I suspect that may be incorrect though.

File size is not an issue as I'm uploading to these platforms and not streaming it myself.

1 Answer 1


-crf 0 does not mean no compression; it's lossless compression. The data is meant to be downsized but with no loss of information.

So, the presets do make a difference because they affect how hard the encoder tries to find predictive information within the source. The sizes obtained and the time taken will be different depending on preset.

  • ok cool so if file size and time to encode are not an issue then setting -crf 0 and -preset veryslow should give me higher quality encode.
    – Westicle
    Nov 29, 2017 at 9:49
  • No. CRF 0 is lossless. So all presets will yield identical quality. Only size and speed will be different.
    – Gyan
    Nov 29, 2017 at 10:02

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