Linux: Fix Audio Problem, PulseAudio
in Linux, if audio doesn't work, you can try
# kill audio process pulseaudio -k
then wait few seconds for it to die. You can check by
# check if PulseAudio is running pgrep -l pulseaudio
then, start PulseAudio again.
# start PulseAudio pulseaudio --start
To start the audio control panel, do:
# start sound level control panel for PulseAudio setsid pavucontrol
now, if your desktop dock sound icon becomes gray, you might need to restart it.
here's a example with xfce.
# restart xfce dock pkill xfce4-panel setsid xfce4-panel
[see Linux: How to Switch to LXDE, Xfce]
Audio Problem Caused by Logitech Webcam
You might have seen this message:
cannot set freq 48000 to ep 0x86
Many people have PulseAudio problem.
The Linux audio problem is caused by the kernel having problem with several popular Logitech webcam. In my case, its Logitech HD Webcam C310 Buy at amazon
In your syslog,
tail -f /var/log/syslog, you get flooded by this message:
kernel: [ 1438.563209] 3:3:4: cannot set freq 48000 to ep 0x86 kernel: [ 1438.563976] 3:3:4: cannot set freq 48000 to ep 0x86 kernel: [ 1438.565348] 3:3:4: cannot set freq 48000 to ep 0x86
You can see this bug report in many places, in Ubuntu, Arch Linux, and in Linux Kernel too. https://bugzilla.kernel.org/show_bug.cgi?id=44281
The solution is just to unplug that webcam.
If you are adventurous, you can disable USB audio module in kernel, like this:
rmmod -w snd-usb-audio modprobe snd-usb-audio
but that means you won't have any sound.