2012-8-17 下午10:51 於 "Tanu Kaskinen" tanu.kaskinen@digia.com 寫道：
Ping?
If card specific pcm definitions are not possible, would it be acceptable to have a generic "front_left:CARD" or "first_channel:CARD" pcm, which would transform "front:CARD" or "hw:CARD" into a mono device?
As pulseaudio server use SND_PCM_NO_AUTO_CHANNEL which diable channel conversion, this left channel device only work with other alsa applications except pulseaudio when your sound card does not support mono.
http://cgit.freedesktop.org/pulseaudio/pulseaudio/commit/?id=ff4af902cf4ac07...
the solution is to change the mixing in pulseaudio by using left channel for this mic and those stereo mic with inverted phase , and average for mono playback device . stereo mic and line-in
how about the 4 channel mic?
-- Tanu
On Fri, 2012-08-10 at 14:25 +0300, Tanu Kaskinen wrote:
Hi,
I'm writing UCM configuration for RX-51 (Nokia N900), and I have a problem: "hw:RX51" can't be opened in mono mode, but there's only one integrated mono microphone, and its audio is routed to the left input channel. Applications will get only silence in the right channel when they use "hw:RX51".
The best solution that I have come up is to define a pcm that converts "hw:RX51" into a mono device. The problem is that I don't know how exactly to do that. I guess the route plugin can be used for that:
pcm.rx51_mono_from_left { type route slave.pcm hw:RX51 slave.channels 2 ttable.0.0 1 }
I tried putting that definition in /usr/share/alsa/cards/RX-51.conf (and also RX51.conf, since it's not entirely clear to me when the dash should be omitted). I have this in the UCM configuration:
Value { CapturePCM "rx51_mono_from_left" CaptureChannels "1" }
This is printed to the PulseAudio log:
(alsa-lib)pcm.c: Unknown PCM rx51_mono_from_left
So the rx51_mono_from_left definition is not loaded. I'm not terribly surprised: I guess the card configuration files are loaded only when necessary, and when PulseAudio tries to open "rx51_mono_from_left", alsa-lib can't really know that it's somehow related to the RX-51 card.
How should I solve this?