Comment 35 for bug 532586

I've been experiencing this bug as well, ever since I upgraded my primary machine to version 10.04 some months ago. I have 2 home-built desktop machines here - a newer one (running with an ASRock N68-S motherboard, Athlon II X2 250 CPU and SB Audigy SE 7.1 soundcard) and a six year old one (running with a MSI KM2M combo board, Athlon XP 2200 CPU and SB Live! 5.1 soundcard).

The newer machine, a dual core running at 3GHz, is affected by this bug, while the older one, a single core running at 1.8GHz is not. The bug only manifests itself when I have the new machine set to surround audio and it disappears immediately when audio is reverted back to stereo audio. I have both the 32bit and 64bit versions of Ubuntu 10.04 installed on the new machine with the latest generic kernels and all updates installed, and they're both affected by this bug. I've tried using the latest alsa drivers in the 64bit Ubuntu, but the issue has remained unaltered by their use.

Once the machine is set to use surround, the issue shows up whenever I watch flash video in a browser, or DVDs or when I listen to locally stored music. The sequence of events on my machine reflects what several others have been describing - pulseaudio is in use and the audio channels are set to 5.1 surround; then after anywhere from a minute to half an hour of playback, there's a sudden jump in CPU usage by the pulseaudio process in one CPU core; once it hits 100% usage of both cores, the pulseaudio process is killed and is replaced by one with a new pid. Once the pulseaudio process has a new pid, programs that were previously accessing pulseaudio will either crash with an error message (eg. Totem Movie Player) or continue to play the video file without audio (eg. VLC 1.0.6 or SMPlayer). With video players that don't crash, it's possible to get the player to access the new pulseaudio process by pausing the video and then disabling and re-enabling the software's audio.

I do think there might be some sort of relationship to the system load. The problem tends to happen more frequently when the CPU is being extensively used. It happens least when music files are played back and the most when the web browser has lots of flash-filled pages running simultaneously or when the video is running in full screen.

I'm going to try an experiment during this week to see if this thing might be audio hardware related. I'll switch the older SB Live card to the new machine and move the Audigy to the older machine. If the problem trades places, it might hopefully help narrow things down a bit.