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