[FFmpeg-user] -preset veryfast produces smallest file, weird

[Ulf Zibis]

Am 15.10.23 um 15:43 schrieb Reindl Harald:
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> Am 15.10.23 um 15:12 schrieb Ulf Zibis:
>> by accident I transcoded a video with -preset veryfast (it took 1 h).
>> So I had to run it again with -preset veryslow (it took 12 h).
>> Now I'm wondering about the file sizes. How can that be?
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> why not?
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> if you prefer fast you don't care about quality
>
> in doubt quality needs space and find a compromise between size and space - you can't have both - and well, depending on the source material fast can be small and good enough in quality
In my understanding quality also needs CPU time.
See: https://trac.ffmpeg.org/wiki/Encode/H.264
There I can read:
"for constant quality encoding, you will simply save bitrate by choosing a slower preset."

As I used the same -crf value for all 3 runs, I'm still wondering, that I experienced the opposite.

-Ulf