[alsa-devel] ALSA, GStreamer and surround

[Takashi Iwai]

At Thu, 29 Mar 2007 14:01:50 +0200,
I wrote:
> 
> At Thu, 29 Mar 2007 13:55:27 +0200,
> Christian F.K. Schaller wrote:
> > 
> > Hi Takashi,
> > Thanks for trying to help us with trying to resolve
> > http://bugzilla.gnome.org/show_bug.cgi?id=410403. 
> > 
> > I tested a bit with a 6-channel .wav file and aplay. It seems it shows
> > the same issues that we are seeing in GStreamer. Namely that if I try:
> > 
> > aplay -D front dust51.wav 
> > Playing WAVE 'dust51.wav' : Signed 16 bit Little Endian, Rate 48000 Hz,
> > Channels 6
> > aplay: set_params:905: Channels count non available
> > 
> > It correctly tells me that it doesn't support outputting this many
> > channels. This is fine for GStreamer as it allows our negotiation to
> > plug in a downmixing element.
> > 
> > However if I do:
> >  aplay -D default dust51.wav 
> > Playing WAVE 'dust51.wav' : Signed 16 bit Little Endian, Rate 48000 Hz,
> > Channels 6
> > 
> > It plays out the 'front' channels, but the remainders just get lost. So
> > when outputting to default neither do alsa downmix by itself or fail
> > telling you that you don't have the needed 6 channels available.
> 
> This is expected behavior.  The "default" PCM is built with plug
> player which absorbs the channel / format / rate differences.  The

s/player/layer/


Takashi