[alsa-devel] Surround and SPDIF on STAC9277

[Takashi Iwai]

At Mon, 26 May 2008 11:15:08 -0400,
Jon Smirl wrote:
> 
> On 5/26/08, Takashi Iwai <tiwai at suse.de> wrote:
> > At Sat, 24 May 2008 17:02:21 -0400,
> >
> > Jon Smirl wrote:
> >  >
> >  > I've figure out that the answer that I'm looking for is AC3 over SPDIF
> >  > support. Now I'm trying to figure out how to make it work in pulse.
> >
> >
> > If you think of real-time conversion to AC3 from linear PCM streams, I
> >  guess pulseaudio doesn't support it natively.
> 
> mesilliac has got it to work. There are instructions here using the a52 plugin.
> http://ubuntuforums.org/showthread.php?p=4451132

Yeah, but it's not a *native* function in pulse :)

> I'm running it right now on Ubuntu 64b. Flash works.
> 
> It has some issues:
>  sound from VLC is broken up
>  mplayer works when it uses surround51 but not with AC3 pass-through
>  my stereo music is getting copied to all six channels which messes up
> the processing the amp.
> 
> Getting this to work simply and reliably would be a nice feature. I
> suspect most people who run SPDIF to their stereo don't realize that
> they are only getting a stereo signal and they need to use something
> like a52.

Right, the plugin is a bit fragile due to its buffer handling as it
starts an individual PCM stream as its slave.  Then both the master
and slave streams can have completely different setups.

I'm willing to fix bugs of a52 plugin but hardly have time,
unfortunately...


Takashi

> 
> >
> >
> >  Takashi
> >
> >
> >
> >  > On 5/24/08, Jon Smirl <jonsmirl at gmail.com> wrote:
> >  > > How are you supposed to get 5.1 audio out of your PC? When I hook the
> >  > >  SPDIF device from my STAC9227/HDA audio up to pulse, pulse says that
> >  > >  the SPDIF channel only supports stereo.
> >  > >
> >  > >  So I go digging around the in STAC9227 datasheet.
> >  > >  http://www.idt.com/?genID=STAC9227
> >  > >
> >  > >  STAC9227 codec only supports 192Khz SPDIF with 4/1*48Khz channels. It
> >  > >  doesn't support 384Khz with 8/1*48Khz channels.
> >  > >
> >  > >  So there are two problems, first the existing Intel HDA/STAC9227
> >  > >  driver is not exposing the 4 channel SPDIF support. Or I can't figure
> >  > >  out how to get to it.
> >  > >
> >  > >  Second, the hardware doesn't seem to support any way to get digital
> >  > >  5.1 audio out of the codec and into my Sony amp. STAC9227 does have
> >  > >  six channel analog out, but my Sony amp doesn't have 6 channel analog
> >  > >  in. Sony amp supports 384Khz 8-channel SPDIF in.
> >  > >
> >  > >
> >  > >  --
> >  > >  Jon Smirl
> >  > >  jonsmirl at gmail.com
> >  > >
> >  >
> >  >
> >  > --
> >  > Jon Smirl
> >  > jonsmirl at gmail.com
> >
> > > _______________________________________________
> >  > Alsa-devel mailing list
> >  > Alsa-devel at alsa-project.org
> >  > http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
> >  >
> >
> 
> 
> -- 
> Jon Smirl
> jonsmirl at gmail.com
>