[FFmpeg-devel] MPEG TS encoding problem on change from stereo to mono, pay for fix

Stefano Sabatini stefano.sabatini-lala
Fri Nov 19 15:26:57 CET 2010

On date Thursday 2010-11-18 21:07:00 +0100, Reimar D?ffinger encoded:
> On Thu, Nov 18, 2010 at 05:09:20PM +0100, Andreas Unterhuber wrote:
> > I published at https://roundup.ffmpeg.org/issue2292 a bug that causes strange noise after change of mono to stereo or similar. 
> > If you can commit a fix to make changing audio channel rates in the demo file (attached in the bug tracker or I will provide another bigger file) work correctly, I'll pay $350.
> Tip for anyone who needs money:
> Look at ffmpeg.c, line 804:
>     if (ost->audio_resample && !ost->resample) {
> This condition is insufficent, ost->resample cannot be re-used
> but must be freed and re-created if the number of channels
> from the decoder changed.
> Strictly, this all also should handle the channel mask properly,
> but that is work beyond this bug-fix.

First attempt, patch fixes:
ffmpeg -i sample.ts sample.wav

but is not yet ready for commit, comments about the approach are

Possible problems: maybe the new function should check for
filter_lenght/log2_phase_count/linear/cutoff parameters, also the
change in ffmpeg.c requires a function call in do_audio_out() so it may
affect performance.
FFmpeg = Fiendish and Fundamentalist Minimalistic Philosophical ExchanGer

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