[pulseaudio-discuss] [alsa-devel] Channel map API patches: to be 3.7 or not to be?

[Takashi Iwai]

At Mon, 17 Sep 2012 18:46:32 +0800,
Raymond Yau wrote:
> 
> > > How about those sound card which use multi plugin for multi channels
> (e.g.
> > > emu10k1 , c0106 and cs4630) as they can also provide a rear or clfe
> device
> > > for independent stereo playback ?
> >
> > The case of emu10k1 is a bit difficult, as the routing is completely
> > dynamic and determined in alsa-lib plugin.  So, my plan for this case
> > is to provide the chmap override in the alsa-lib config definition for
> > emu10k1 surrounds.
> >
> But the routing of device 0 "hw" is not as same as front device since the
> driver pan the output to both front and rear jacks (upmixing).

The hw device doesn't provide any map.  It's only for "front", "rear"
whatever in strict channel position definitions.

> Does all pcm devices support channel map ?

No.  The channel map is an optional feature.

> How about those 16 channels multichannel playback and capture devices ?
> 
> card 0: Live [SB Live! Platinum [CT4760P]], device 2: emu10k1 efx
> [Multichannel Capture/PT Playback]
>   Subdevices: 8/8
> 
> card 0: Live [SB Live! Platinum [CT4760P]], device 3: emu10k1 [Multichannel
> Playback]
>   Subdevices: 1/1
>
> **** List of CAPTURE Hardware Devices ****
> 
> card 0: Live [SB Live! Platinum [CT4760P]], device 2: emu10k1 efx
> [Multichannel Capture/PT Playback]
>   Subdevices: 1/1

Such devices are not supported.  If any, they can be mapped using
DRIVER_SPEC flag.


> BTW. It seem that the patch for USB audio is still missing as some USB card
> support 5.1/7.1

Feel free to submit a patch :)


Takashi