[alsa-devel] alsa jack plugin

[torbenh]

On Fri, Nov 19, 2010 at 02:15:54PM +0100, torbenh wrote:
> On Wed, Nov 17, 2010 at 03:16:32PM +0800, Raymond Yau wrote:
> > 2010/11/12 Paul Menzel <paulepanter at users.sourceforge.net>
> > 
> > > Am Mittwoch, den 10.11.2010, 11:18 +0100 schrieb torbenh:
> > > > On Mon, Nov 08, 2010 at 10:26:47AM +0100, torbenh wrote:
> > > > >
> > > > > the alsa jack plugin has quite some problems:
> > > > > a) does not work correctly with mplayers alsa output. (and quite a few
> > > > >    others)
> > >
> > 
> > AFAIK, mplayer , aplay and the alsa-jack plugin 1.0.1still working with
> > jack-0.118
> > 
> > So you have to tell the jack plugin fail to work from  from which version of
> > jack if jack change the protocol
> 
> jack did not change the protocoll.
> 
> however, the write to the socket fd might block.
> doing potentially blocking things in jacks process callback is not
> legal. (this kind of problems only show under low-latency situations,
> period_size of 128 and lower)
> 
> the result of the blocking write is jack kicking the client.
> and just making the fd NONBLOCK, "fixed" the problem.
> (it seems to cause some other problems down the road, since some
>  bytes written to the fd get lost)
> 
> i would really like to exchange the socket for a signalfd.
> increasing the signal count of the fd would never block.

err... that should read eventfd, obviously :S
> 
> (but i am not sure about the requirements, signalfd only exists since
>  2.6.27, and i am not sure, if the old socket based code should be left
>  in there as a fallback)
> 
> 
> 
> > 
> > The current Documentation of jack plugin "doc/README-jack" has a mistake
> > 
> > 
> >          pcm.jack {
> >                  type jack
> >                  playback_ports {
> >                          0 alsa_pcm:playback_1
> > -                         1 alsa_pcm:playback_1
> > +                        1 alsa_pcm:playback_2
> >                  }
> >                  capture_ports {
> >                          0 alsa_pcm:capture_1
> > -                        1 alsa_pcm:pcapture_1
> > +                        1 alsa_pcm:pcapture_2
> >                   }
> >          }
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> 
> -- 
> torben Hohn
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-- 
torben Hohn