CODEWITHSUNDEEP
ffmpegh.264lossless-compression
Mephisto
Mephisto

Reputation: 690

Is H.264 used with CRF 0 really strictly lossless?

I am surprised by how small files are when encoded in ffmpeg with the libx264 codec in Constant Rate Factor mode equals zero (-crf 0) that, according to the documentation, is "lossless".

I would like to make sure what the word "lossless" here means. I would like to know if it follows my personal definition of lossless video: After encoding a video, you can confidently bet the life of your mother that, once you play it, the numerical values in the pixels of the restored video will be identically equal (within maybe a factor 0.00001 due to the floating point arithmetic) to the original.

Does the H.264 lossless encoding follow my definition, or do they call it "lossless" because it is visually very close, very beautiful, whatever... ?

Upvotes: 3

Views: 7584

Answers (1)

Валерий Заподовников
Валерий Заподовников

Reputation: 438

No, it is not, only for 8 bit that is true. Only qp 0 is lossless for 10 bit, since that requires high444 profile, not high 10 that does not support lossless but crf 0 does not block high 10 profile. Check in mediainfo that it is correct profile, always.

Upvotes: 3

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