[FFmpeg-user] Possible to speed up/down video while keeping audio pitch?

[Paul B Mahol]

On Mon, Mar 25, 2024 at 12:54 AM Laine Lee <llee040 at sbcglobal.net> wrote:

>
>
> > On Mar 24, 2024, at 5:31 PM, Bo Berglund <bo.berglund at gmail.com> wrote:
> >
> > I know how to use ffmpeg to adjust the video/audio sync and that is a
> real
> > simple command not requiring any remuxing or such. This is what I use in
> my
> > audiosync script and it runs very fast:
> >
> > ffmpeg -i $SOURCEFILE -itsoffset $DELAY -i $SOURCEFILE -map 1:v -map 0:a
> -c copy
> > $TARGETFILE
> >
> >
> > But is it possible also to modify an mp4 video file to *play*
> faster/slower than
> > original while keeping the accompanying audio pitch the same?
> >
> > It *can* be done for instance in the VLC video player on playback, but
> can one
> > also modify the video file itself using ffmpeg so it will play at the
> new speed
> > while keeping audio recognizable (not Donald Duckie)?
> >
> > If so how is it done?
> >
> >
> > --
>
> Sounds to me as though you want to change tempo of the audio stream. I
> believe there’s a pipe from ffmpeg to Sox to handle it, but for that you
> will extract audio, apply the tempo change, then remux. Changing tempo by a
> factor greater than one reduces duration, and by a factor less than one
> increases duration.
>

FFmpeg have tempo audio filter called atempo. No need to use obsolete SoX.


>
> L. Lee
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