I have an Intel HDA stac9205 soundcard in my Dell Inspiron 1720, and it
does not contain a hardware-based micboost for the digital microphone
(that +20dB hard mic gain you see in gnome volume control in some
soundcards). Ekiga and skype are almost impossible to use, because the
microphone volume is too low. This problem can be solved by using
software gain to replace the missing hardware gain. The original
asound.conf in the beginning of this thread, using pulse audio as a
backend, does not provide software gain. I'm providing a variation which
provides software gain for the microphone and adds an independent volume
track "+50dB Mic" in alsamixer/gnome-mixer. I believe it might be useful
also for anyone else whose +20dB mic boost toggle is missing from the
volume control.
1) replace your /etc/asound.conf with the contents below.
2) restart alsa: sudo /etc/init.d/alsa-utils restart
3) see if you have the new track: amixer -c 0 controls | grep 50dB
4) at this point, I did a reboot and the new control showed up in my
gnome-volume-control in the recording tab. I'm not quite sure what to do if it
does not show up in the graphical volume control, but you can manipulate its
value in the command line if the new track is not present graphically: amixer
-c 0 cset numid=<numid-from-step-3> 60% (100% might be too loud). You might
also use alsamixer to modify its value, and test using 'arecord -D pulse -f cd
| aplay'
Because I'm using hw:0,0 as my microphone slave pcm, I can only have one
application at a time (e.g. the test above but not skype) using the
amplified microphone. Using a 'pcm.pulse0 { type pulse }' device as my
slave mic instead, in order to share the microphone among several
applications, does not seem to work. Any suggestions for improvement?
###[begin of asound.conf]###
pcm.pulse {
type asym
playback.pcm {
type pulse
}
#software gain upto 50dB for digital microphone
capture.pcm {
type softvol
slave.pcm "hw:0,0"
#slave.pcm "pulse0"
control {
name "+50dB Mic Capture Volume"
card 0
}
max_dB 50.0
}
}
ctl.pulse {
type pulse
}
pcm.!default {
type plug
slave.pcm "pulse"
}
ctl.!default {
type plug
slave.pcm "pulse"
}
###[end of asound.conf]###
Special thanks to tiwai for adding the max_dB option in softvol: http
://hg-mirror.alsa-project.org/alsa-lib/rev/75a5fa8dc7d5
--
Default ALSA device must use PulseAudio, otherwise ALSA applications may fail
https://bugs.launchpad.net/bugs/198453
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