[Libav-user] problem while using swresample library

[Rafi Fisher]

hello

  the above  problem was solved. since i did not have the latest ffmpeg
libs version downloaded.

  still i have some problem when for example transcoding :
     from: mp4 file  48khz 16bit stereo  downsampled  to
     to :     wav file   11khz 16bit stereo
 i dont get the same wav file compared to the wav file i got by ruuning the
ffmpeg.exe utility
 my file size is smaller & the quality of the audio less good compared to
the ffmpeg.exe wav file.

 do you have an idea why i get different results ?
 because when i transcode without downsampling i get excatlly the same wav
file.

    thanks a lot rafi

On Tue, Dec 4, 2012 at 12:14 PM, Stefano Sabatini <stefasab at gmail.com>wrote:

> On date Monday 2012-12-03 17:52:57 +0200, Rafi Fisher encoded:
> > hello
> >
> >   i'm using *swresample lib*. my code is used to convert mp2 or mp4 into
> > wav file.
> >   the code fragment :
> >     .......
> >
> >     SwrContext *swr = swr_alloc();
> >     ret = av_opt_set_int(swr, "in_channel_layout",  AV_CH_LAYOUT_STEREO,
> 0);
> >     ret = av_opt_set_int(swr, "out_channel_layout",  AV_CH_LAYOUT_MONO,
> >  0);
> >     ret = av_opt_set_int(swr, "in_sample_rate",     IN_SAMPLE_RATE,
>  0);
> >     ret = av_opt_set_int(swr, "out_sample_rate",   OUT_SAMPLE_RATE,
> 0);
> >     ret = av_opt_set_int(swr, "in_sample_fmt",      AV_SAMPLE_FMT_S16,
> 0);
> >     ret = av_opt_set_int(swr, "out_sample_fmt",     AV_SAMPLE_FMT_S16,
> 0);
> >     ret = swr_init(swr);
> >
> >     .......
> >
> >     out_samples = swr_convert(swr, output, out_samples,(const uint8_t **)
> > (inframe->data), in_samples);
> >     if out_channel_layout = AV_CH_LAYOUT_ STEREO resampling works fine
> >
> >     if out_channel_layout = AV_CH_LAYOUT_MONO  & other set options remain
> > same it fails that is:
> >
>
> >     the swr_convert fails that is somwhere inside the code of this
> function
> > there is a call to* exit* which is  problematic by itself (exit a
> program from av. library)
> > instead of returning some error code.
> >
>
> There is no call to exit() in libswresample, it seems more likely like
> a crash. Make sure that you correctly allocated the samples buffers.
>
> Also check my recently posted resampling example:
> http://thread.gmane.org/gmane.comp.video.ffmpeg.devel/155151
>
> >         help will be appreciated thanks rafi
> --
> FFmpeg = Forgiving and Fostering Mega Puristic Explosive Genius
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