Public bug reported:
I have A-Link SU51 usb sound card and problems with sound quality. If I
enable 5.1 surround sounds by adding 'default-sample-channels=6' to
/etc/pulse/daemon.conf sounds starts rasping. This bug exists only with
my HP Compaq CQ50-110EO laptop, if I plug same usb sound card to my Acer
Aspire laptop and enable 5.1 surround sounds, there won't be any
problems. I think this is bug with alsa because I see same rasping if I
remove pulseaudio and use only alsa wiht surround sounds. Stereo sound
doesn't cause any quality problems even if pulseaudio is in use.
It is very interesting how same sound card is working perfectly with
that Acer laptop but causes so much problems with my HP Compaq machine.
But even more interesting is that if I open glxgears in terminal,
rasping sound stops immediately and when I close glxgears window rasping
sound strikes back. I don't really understand this :)
This is what 'aplay -l' says:
**** List of PLAYBACK Hardware Devices ****
card 0: NVidia [HDA NVidia], device 0: CONEXANT Analog [CONEXANT Analog]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 0: NVidia [HDA NVidia], device 1: Conexant Digital [Conexant
Digital]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 0: NVidia [HDA NVidia], device 3: NVIDIA HDMI [NVIDIA HDMI]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 1: Audio [USB Audio], device 0: USB Audio [USB Audio]
Subdevices: 0/1
Subdevice #0: subdevice #0
I also noticed that pulseaudio gives some error messages:
W: alsa-util.c: Cannot find fallback mixer control "Mic" or mixer
control is no combination of switch/volume.
W: alsa-util.c: Cannot find fallback mixer control "PCM" or mixer
control is no combination of switch/volume.
E: module-alsa-sink.c: ALSA woke us up to write new data to the device, but
there was actually nothing to write! Most likely this is an ALSA driver bug.
Please report this issue to the ALSA developers. We were woken up with POLLOUT
set -- however a subsequent snd_pcm_avail_update() returned 0.
See also my hardware summary in attachment.
** Affects: ubuntu
Importance: Undecided
Status: New
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Rasping sound with usb audio and 5.1 surround sounds
https://bugs.launchpad.net/bugs/326693
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