I've been configuring my Raspberry Pi 1B to capture sound from a USB webcam, and output sound via the built-in sound card 3.5mm output. Testing the devices individually using aplay and arecord are working fine, though I need to specify the capture device explicitly since it's not the default device.I read up about asound.conf and seeing some examples on how to create a combined capture and playback device by combining the two half-duplex devices for ease of use / control, using the asym module:
$this->bbcode_second_pass_code('', '
pcm.usb
{
type hw
card <USB capture device ID>
}
pcm.internal
{
type hw
card ALSA
}
pcm.!default
{
type asym
playback.pcm
{
type plug
slave.pcm "internal"
}
capture.pcm
{
type plug
slave.pcm "usb"
}
}
ctl.!default
{
type asym
playback.pcm
{
type plug
slave.pcm "internal"
}
capture.pcm
{
type plug
slave.pcm "usb"
}
}
')
Testing aplay and record without specifying a device works nicely (arecord previously required me to specify a device, since the default PCM card does not have a capture device). So the playback / output of asym is working nicely.
However, when I try to run amixer or alsamixer to test controlling the volume, I get the following error:
$this->bbcode_second_pass_code('', '
ALSA lib dlmisc.c:254:(snd1_dlobj_cache_get) Cannot open shared library /usr/lib/alsa-lib/libasound_module_ctl_asym.so
cannot open mixer: No such device or address
')
I've tried checking all my packages - I got following alsa packages installed:
alsa-lib
alsa-plugins
alsa-tools
alsa-utils
but pacman -Ql against all of these yields nothing with libasound_module_ctl_asym.so. The alsa-plugins package seems to have ctl libraries for pulse, oss and arcam_av though. I've checked the list of files located in the equivalent i686 and x86_64 packages online, none of the above packages show them having the control module either. Google hasn't yielded much information - only 1-2 other people have had this issue (also on rPis), but there was no solution posted.
Any ideas? Am I missing something obvious? If there's another way I can achieve this (merging the individual playback and capture devices into one, and setting it as the default), do let me know.