On Wed, 16.07.08 16:30, Lennart Poettering (mznyfn@xxxxxxxxxxx) wrote: > Heya! > > With 1.0.17rc3 snd_pcm_rewind() is broken for softvol as it seems: > > - Sometimes the sound becomes heavily distorted after such a seek: > > http://mailman.alsa-project.org/pipermail/alsa-devel/2008-June/008860.html > > - And snd_pcm_rewind() might return a value that is higher than was > passed in, which as far as I understood should never happen: > > http://mailman.alsa-project.org/pipermail/alsa-devel/2008-April/007308.html > > These two issues might be caused by the same error. > > Takashi, Jaroslav, how can I bribe you into fixing this? I'd love to > release my new PulseAudio version soon which heavily relies on > snd_pcm_rewind(), but unfortunately the most important driver (hda > with softvol) makes the most problems with it. :-( Hmm, if I understand snd_pcm_plugin_rewind() in pcm_plugin.c correctly, then I read it like this: 1. we clamp the input frames to hw_avail 2. we convert this to slave frames 3. we issue the rewind 4. we convert back to client frames 5. we return hw_avail. Step #1 seems wrong to me. The code will make sure that we rewind as least as much as can be written right now. Does that make any sense? I don't think so. Shouldn't this be a clamp that makes sure that we rewind at most as much as the buffer is filled right now? I.e. something along the lines of: if (frames > buffer_size - n) frames = buffer_size - n; Also, step #5 seems wrong to me. Shouldn't we return the result of the second conversion? I.e. shouldn't "return n" be replaced by "return (snd_pcm_sframes_t) frames"? I am puzzled though, not sure if I understood that function correctly at all. Lennart -- Lennart Poettering Red Hat, Inc. lennart [at] poettering [dot] net ICQ# 11060553 http://0pointer.net/lennart/ GnuPG 0x1A015CC4 _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
