Bug#634842: pulseaudio: Logitech C250 Webcam microphone works with wrong sample rate

Dmitry A. Istselemov distselemov at yandex.ru
Wed Jul 20 13:58:20 UTC 2011

Package: pulseaudio
Severity: normal

Logitech C250 Webcam microphone works with wrong sample rate in pulseaudio. All
records making with this microphone sounds very fast. Pulseaudio recognize this
mic as one having 48000Hz sample rate. In fact I beleive it should be 16000Hz.
The webcam is connected using USB interface. At first it appeard in Skype (and
in Skype it doesn't work even now neither with nor without pulse). The
workaround for this was making an asound.conf with the next lines:

pcm.skype {
    type plug
    slave {
        pcm "hw:1,0"
        rate 16000
removing pulseaudio and using this plug device as an input device for skype.

But checking the microphone by executing "arecord -D plughw:1,0 -vv
RecTest.wav" and then playing the record shew that it worked fine. The sound
was good and everything was fine with the speech speed. Actually I can't
understand why the mic doesn't work in skype but works great in all the other
programs (I used audacity and the above arecord line for testing) when I'm
using alsa only? And why it makes just noise (speech with very fast speed)
everywhere when I'm using pulse? This problem also exist when I use native
2.6.39 debian kernel.

-- System Information:
Debian Release: wheezy/sid
  APT prefers testing
  APT policy: (990, 'testing'), (900, 'testing-proposed-updates'), (101, 'unstable')
Architecture: amd64 (x86_64)

Kernel: Linux 2.6.39-3.dmz.2-liquorix-amd64 (SMP w/4 CPU cores; PREEMPT)
Locale: LANG=ru_RU.UTF-8, LC_CTYPE=ru_RU.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash

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