[vlc-devel] mp3 transcoding creates slow audio (was Re: Slow audio when streaming flv

[Rov Juvano]

On Mon, Jul 07, 2008 at 05:05:43PM -0700, Dave Still wrote:
> I did some more testing, and it appears that the slow audio is
> happening for any a/v file where audio is transcoded is transcoded to
> mp3.  For example, the following command-line:
>
> ./VLC.app/Contents/MacOS/VLC -vvv -I dummy ~/Movies/makeup.wmv --sout
> "#transcode
> {vcodec
> =
> mp4v
> ,acodec
> =
> mp3
> ,samplerate
> =
> 22050
> ,ab
> =
> 128
> ,vb
> =512,width=320,height=240,channels=2}:std{access=file,dst=stream.mov}"
> --audio-filter scaletempo vlc://quit
>
> The resulting stream.mov plays back in QuickTime, but the audio is
> hella-slow.  Result is the same with or without the scaletempo audio
> filter.
>
> - Dave

I narrowed this down to:
commit 79bd720139a011cd603efed8b6f7be297e6d55ce
Date:   Tue Apr 8 16:00:22 2008 +0200

    When specifying --sout-transcode-samplerate and --sout-transcode-channel, set the OUTPUT format instead of the INPUT
    
    Fix resampling when using mp4a (faac is the only option atm)


With the following patch, transcode keeps the pitch when
resampling to an mp3.  I had to specify acodec=mpga to find
an encoder.

--
rovjuvano
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