crackling microphone

[riddicc]

Hi!

When I send a 800Hz sine wave with rate 12345 to pcm.outmic and
when I arecord from pcm.micend at rate 8000 with 1 channel (/etc/asound.conf),
then I get a lot of tiny little gaps (see attachment) and a lot of messages like "overrun!!! (at least 0.014 ms long)" (the "ms" vary from 0.008 to 0.043; and arecord continues to record) and sometimes even this error: "arecord: xrun:1672: read/write error, state = RUNNING" (it causes arecord to terminate).

1. speaker-test -D outmic -t sine -f 800 -c2 -r 12345

2. arecord -D micend -r 8000 -c 1 -f S16_LE /tmp/bla.wav

twinkle makes even bigger gaps, when I let it use pcm.micend as microphone...
But with hw:Generic,0,0 as mic device twinkle works fine...
LubosD/twinkle#207

"samplerate_best" and "samplerate_order" seems to make it worse...

How can I fix that?

Thx.

Bye.

[riddicc]

with some more plug-plugins (/etc/asound.conf) it works nicely... giggle :) w00t
-arne

[riddicc]

oops...
now the gaps are gone, when I use pcm.micend, but there is permanent noise and there are echoes that are not in hw:Generic,0,0...

in the log file i found this:

ALSA capture buffer settings.
Rate = 8000 frames/sec
Frame size = 2 bytes
Periods = 8
Period size = 682 bytes
Buffer size = 5456 bytes
Can pause: no

seems like the period_size is funny...

-arne

[riddicc]

when I change the rate value in pcm.micnat from 48000 to 44100 plug:micnat sounds much better...
now it is just the pcm.micmul, that does not work so good...
but that is possibly caused by some other mistake in asound.conf...
-arne

[riddicc]

1. it seems like pcm.micnat still has some extra crackling... but it is acceptable...
2. but: pcm.micmul stays bad...
3. and: skype does not like to use pcm.default, if it points to plug:micnat with the asym plugin...

how can i fix it without using pulseaudio, which twinkle does not support?

-arne

[riddicc]

is it possible, that pcm.micnat crackles, because:
the alsa-clock is different from the HD-Audio Generic clock?

if yes: how can i fix it without writing my own program, that reads from hw:Generic,0,0 at its native rate and injects at system-clock-48kHz to pcm.outmic?

-arne