Hi,
I'm running Slackware -current (updated 17 Oct 2015) with a custom build
of kernel 4.1.6 and ALSA 1.0.29. My sound hardware is correctedly
detected, and audio works:
"
$ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: PCH [HDA Intel PCH], device 0: VT1802 Analog [VT1802 Analog]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 0: PCH [HDA Intel PCH], device 2: VT1802 Alt Analog [VT1802 Alt Analog]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 0: PCH [HDA Intel PCH], device 3: HDMI 0 [HDMI 0]
Subdevices: 1/1
Subdevice #0: subdevice #0
"
But there are a slew of stock PCM definitions set for this hardware that
I don't want, particularly the surroundXX ones:
"
$ aplay -L
null
Discard all samples (playback) or generate zero samples (capture)
sysdefault:CARD=PCH
HDA Intel PCH, VT1802 Analog
Default Audio Device
front:CARD=PCH,DEV=0
HDA Intel PCH, VT1802 Analog
Front speakers
surround21:CARD=PCH,DEV=0
HDA Intel PCH, VT1802 Analog
2.1 Surround output to Front and Subwoofer speakers
surround40:CARD=PCH,DEV=0
HDA Intel PCH, VT1802 Analog
4.0 Surround output to Front and Rear speakers
surround41:CARD=PCH,DEV=0
HDA Intel PCH, VT1802 Analog
4.1 Surround output to Front, Rear and Subwoofer speakers
surround50:CARD=PCH,DEV=0
HDA Intel PCH, VT1802 Analog
5.0 Surround output to Front, Center and Rear speakers
surround51:CARD=PCH,DEV=0
HDA Intel PCH, VT1802 Analog
5.1 Surround output to Front, Center, Rear and Subwoofer speakers
surround71:CARD=PCH,DEV=0
HDA Intel PCH, VT1802 Analog
7.1 Surround output to Front, Center, Side, Rear and Woofer speakers
hdmi:CARD=PCH,DEV=0
HDA Intel PCH, HDMI 0
HDMI Audio Output
"
These stock definitions not only clutter my device list, but produce
messy warning notices when running many of my ALSA apps. Here is an
example from a command-line program included with the Composers Desktop
Project tools:
"
$ listaudevs
ALSA lib pcm.c:2267:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.rear
ALSA lib pcm.c:2267:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.center_lfe
ALSA lib pcm.c:2267:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.side
ALSA lib pcm_route.c:867:(find_matching_chmap) Found no matching channel map
ALSA lib pcm_route.c:867:(find_matching_chmap) Found no matching channel map
ALSA lib pcm_dmix.c:963:(snd_pcm_dmix_open) The dmix plugin supports
only playback stream
ALSA lib pcm_dmix.c:963:(snd_pcm_dmix_open) The dmix plugin supports
only playback stream
Device Input Output Name
0 2 2 HDA Intel PCH: VT1802 Analog (hw:0,0)
1 0 8 HDA Intel PCH: HDMI 0 (hw:0,3)
2 128 128 sysdefault
3 0 2 front
4 0 2 surround40
5 0 2 surround51
6 0 2 surround71
7 0 8 hdmi
8 0 128 main
9 0 2 dmix
*10 0 128 default
"
What I'd like to do is UNset the unwanted PCM definitions in
/etc/asound.conf (i.e., without having to doctor
/usr/share/alsa/alsa.conf), and I'm not clear on the proper way to do this.
The documentation I've found online has been extremely helpful in
describing how to configure ALSA for a variety of use cases, but
unsetting unwanted PCM definitions does not seem to have been covered in
any of them. The one reply I received to my post on LinuxQuestions
suggested I try this mailing list, and I was not able to find anything
that seemed to specifically address this topic in the archives.
Can anyone suggest something I might have overlooked?
\\ Arthur
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