Strange audio problems

[Mark Fraser]

On Friday 28 Dec 2012 17:29:26 Basil Chupin wrote:
> On 26/12/12 06:03, Mark Fraser wrote:
> > My daughter's been having problems with the audio breaking up on her
> > computer for a while, but today I went into PulseAudio Volume Control and
> > noticed that the output device port was constantly switching between
> > Analogue Output and Headphones. Running alsamixer from the command line
> > also showed this, but with the surround channels even though they're not
> > used.
> > 
> > Can anyone offer any advice on how to sort this out?
> > 
> > Thanks.
> 
> When asking a question always pays to offer the people some information
> about the "computer", the OS (ie distro and version being run) and
> anything else which *you* would like to know if you were to attempt and
> answer someone's request for help. OK?

Sorry, it was a quick email before shutting the computer down. Here is some 
more info - she is running Kubuntu 12.10, but it has been happening for a a 
releases which I've been able to fix before.

> The first question I would ask is: is this an occurrence which suddenly
> afflicted your daughter or is this something which is now happening
> because you/she installed (some version) of Kubuntu?
> 
> The next question is: is this sound being generated by the motherboard's
> onboard chipset or by a PCI(/E) card? And which of these is
> selected/activated in the BIOS (you cannot have both activated
> [disclaimer here])?

This is with the on board sound on a Gigabyte GA-M68SM-S2L motherboard. Lspci 
shows the following info:
Audio device: NVIDIA Corporation MCP67 High Definition Audio (rev a1)
        Subsystem: Giga-byte Technology Device a002
        Flags: bus master, 66MHz, fast devsel, latency 0, IRQ 21
        Memory at f5000000 (32-bit, non-prefetchable) [size=16K]
        Capabilities: [44] Power Management version 2
        Capabilities: [50] MSI: Enable- Count=1/1 Maskable+ 64bit+
        Capabilities: [6c] HyperTransport: MSI Mapping Enable- Fixed+
        Kernel driver in use: snd_hda_intel
        Kernel modules: snd-hda-intel

> Last question: when using Alsamixer did you use F6 to select the sound
> source/card, and did you get a full list of what channels are available
> for configuration **?

Yes, I used F6 and it had a few different sound cards, one of them being HDMI 
output on the graphics card. I selected the on board audio.

> ** In many cases, pulseaudio stuffs up alsamixer and alsamixer only
> displays about 3 or 4 available channels; disabling or removing
> puseaudio then enables alsamixer to display all channels.

This is the same set up as my wife is using on her computer and her audio is 
fine.