My apologies if this should have gone to the alsa-user list, but as far as I
can tell, the problem I'm encountering may be more of a design issue than
one of user error. Also, I apologize, if this issue has already been raised
-- I couldn't figure out how to search the mailing list archives
(http://www.geocrawler.com/lists/3/SourceForge/12349/0/).
I'm using a new M-Audio Audiophile 2496 sound card, and the following ALSA
packages:
alsa-driver-0.9.0beta9
alsa-lib-0.9.0beta9
alsa-oss-0.9.0beta10a
alsa-utils-0.9.0beta9
My question is regarding the 'amixer' utility that was included with
alsa-utils-0.9.0beta9. I was thrilled to discover I might be able to query
and control all aspects of my sound card's mixer, via the command-line.
However, when I attempted to do so, I ran into some problems. To be honest,
I didn't really get past the 'set' or 'sset' command. The specific problem
I'm having is that I seem able to mute an input (i.e. 'capture' channel of a
track), but not unmute it, directly. The following command will mute Left
and Right, on the capture channel of the 'Multi,0' track:
amixer set Multi,0 nocapture
But, to unmute it, it seems I must execute this sequence:
amixer set Multi,0 nocapture
amixer set Multi,0 capture toggle
I don't have a big problem with that (especially since I'm doing this inside
of a script), but rather with the fact that I was unable to find a
sufficiently detailed description of the grammar for the amixer set/sset
command. For example, the man page says:
set or sset <SCONTROL> <PARAMETER> ...
IMO, <PARAMETER> and '...' need to be more fully specified. I was reduced
to spending several minutes trying various combinations and sequences of
'capture', '<number>', 'mute', 'unmute', 'nocapture', 'playback', 'on',
'off', 'left', 'right', etc. in an attempt to determine how to independently
or jointly control the volume and muting of the left and right channels of
playback and capture, for a given track. From this experience, I can say
that I think the problem of insufficient documentation of set/sset is
compounded by apparently inconsistent, context-dependent behavior of some of
the above tokens.
I suppose I should probably dive into the code, but I'm wondering whether
this problem is localized to the 'amixer' program, or that there may be any
part of this parsing function that's left up to the driver.
If I had more time, I'd offer to implement any agreed-upon changes, myself.
Still, I thought it might be worthwhile to raise awareness of the issue and
hopefully even clear up some confusion I may have had, that prevented me
from properly using this command.
Matt
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