Le nonidi 29 messidor, an CCXXIII, Emanuel Berg a écrit :
> ffmpeg -i $song -i $movie ${name}-norm.$ext
> local song=$name.mp3
> ffmpeg -i $movie $song
At both steps, you are transcoding. That means you are paying the MP3 toll
twice, including CPU time and quality loss.
I do not know how normalize-audio operates. It is theoretically possible to
adjust the volume without transcoding, but I suppose this is tricky, and I
do not know if normalize-audio implements it.
If normalize-audio can do it, then using "-c copy" to avoid transcoding is
the correct solution. If it can not, then use a raw PCM format as
intermediate format; the obvious choice is WAVE.
Also, you say that normalize-audio is lightning fast, this is bad sign,
because computing the volume of a clip accurately is expensive.
Regards,
--
Nicolas George
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