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 -- Rasping sound with usb audio and 5.1 surround sounds https://bugs.launchpad.net/bugs/326693 You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs