Mic boost (igain) for uaudio

Chris Billington billington.chris at gmail.com
Sun Mar 11 13:37:35 UTC 2007


I use a USB audio device (phone handset) for VOIP on 6.2-stable.

The audio from the USB device is really low level- correspondents can
hardly hear me.

The uaudio0  device appears as /dev/dsp1.0, /dev/dsp1.1, etc:

/dev/dsp1.0     /dev/dsp1.2     /dev/dsp1.4
/dev/dsp1.1     /dev/dsp1.3     /dev/dsp1.5

dmesg|grep pcm:

dmesg|grep pcm
  timer: 0x000100ef therm: 0x00010000 err: 0x0001000f pcm: 0x00010000
pcm0: <Intel ICH6 (82801FB)> port 0xe000-0xe0ff,0xe400-0xe43f mem
0xffe3fc00-0xffe3fdff,0xffe3f800-0xffe3f8ff irq 17 at device 30.2 on
pcm0: Reserved 0x200 bytes for rid 0x18 type 3 at 0xffe3fc00
pcm0: Reserved 0x100 bytes for rid 0x1c type 3 at 0xffe3f800
pcm0: [MPSAFE]
pcm0: <Avance Logic ALC655 AC97 Codec (id = 0x414c4760)>
pcm0: Codec features 5 bit master volume, no 3D Stereo Enhancement
pcm0: Primary codec extended features reserved 1, center DAC, surround
DAC, LFE DAC, reserved 5
pcm0: ac97 codec dac ready count: 0
pcm0: sndbuf_setmap 1e469000, 4000; 0xd4f49000 -> 1e469000
pcm0: sndbuf_setmap 1e45f000, 4000; 0xd4f4d000 -> 1e45f000
pcm0: measured ac97 link rate at 47997 Hz, will use 48000 Hz
pcm1: <USB audio> on uaudio0
pcm1: using a default buffer size of 16384 bytes

# cat /dev/sndstat
FreeBSD Audio Driver (newpcm)
Installed devices:
pcm0: <Intel ICH6 (82801FB)> at io 0xffe3fc00, 0xffe3f800 irq 17 bufsz
16384 kld snd_ich (1p/1r/4v channels duplex default)
pcm1: <USB audio> at ? kld snd_uaudio (1p/1r/4v channels duplex)

For the onboard audio I can set mic boost on (I think, looking at ac97.c) bu
# mixer -f /dev/dsp0 igain 100
Setting the mixer igain from 100:100 to 100:100.

However for the /dev/dsp1 I get:

# mixer -f /dev/dsp1 igain 100
mixer: unknown device: igain
usage: mixer [-f device] [-s | -S] [dev [+|-][voll[:[+|-]volr]] ...
       mixer [-f device] [-s | -S] recsrc ...
       mixer [-f device] [-s | -S] {^|+|-|=}rec rdev ...
 devices: pcm, mic
 rec devices:

The usb audio device appears to mixer (and kmixer, etc) as two output
channels pcm and mic.

Is there any way to add igain (20dB mic boost) for USB audio?


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