Fedora 17, pulseaudio, KDE, phonon, distortion

[depierce]

I installed Fedora 17 x86_64 a couple nights ago. Up to date. I used the KDE spin for the initial install and am using the K Desktop. My current repos include fedora, adobe, google, livna, rpmfusion (rawhides and testing are off). My sound card is a Creative Labs SB X-Fi, using snd_ctxfi.

My problem - my very serious, I'm-going-to-ditch-Fedora-for-good problem - is sound distortion occurring in any audio app, using any codec, after X amount of time, where X is random. The distortion may be an echo effect of some kind, but when it starts, it is so horrible and persistent I am forced to kill whatever audio app is running lest I damage my ears or my Grado SR325s. And I'm not certain I've avoided either horrid end, actually.

I have no clue where to start. This card works as expected, at least in standard stereo mode, in Windows XP, Windows 7 and FreeBSD 9.0. Any pointers would be appreciated.

[tashirosgt]

My more or less uninformed suggestions:

Determine which kernel module is used for your sound device by finding it in the output of lspci

lspci | less

Then get a more detailed report by using lspci with the specific slot number of the device. For example,

lspci -v -s 00:14.2
00:14.2 Audio device: ATI Technologies Inc SBx00 Azalia (Intel HDA) (rev 40)
	Subsystem: Giga-byte Technology Device a002
	Flags: bus master, slow devsel, latency 32, IRQ 16
	Memory at fdff4000 (64-bit, non-prefetchable) [size=16K]
	Capabilities: [50] Power Management version 2
	Kernel driver in use: snd_hda_intel
	Kernel modules: snd-hda-intel

That would give you a specific name to use in searching for problems with the module.


One recommendation from http://fedoraproject.org/wiki/How_to...sound_problems is to temporarily remove alsa-plugins-pulseaudio. This got my FC 17 machine from no-audio to audio, so (not being a sophisticated user of audio) I just left it removed.

[depierce]

There don't appear to be any outstanding bugs on the snd_ctxfi driver. I've never had an issue with it on other Linux distros either recently. I am inclined to believe, based on prior experience with Fedora and pulseaudio that ripping out pulseaudio and setting up a proper alsa conf would solve the issue. But that clearly isn't how Fedora was designed and I'd like to give the "community" a chance to help me straighten this out.

# lspci -vv -s 05:02.0
05:02.0 Multimedia audio controller: Creative Labs SB X-Fi
Subsystem: Creative Labs Device 0031
Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
Latency: 32 (1000ns min, 1250ns max), Cache Line Size: 32 bytes
Interrupt: pin A routed to IRQ 18
Region 0: I/O ports at d200 [size=32]
Region 1: Memory at f1000000 (64-bit, non-prefetchable) [size=2M]
Region 3: Memory at ec000000 (64-bit, non-prefetchable) [size=64M]
Capabilities: [40] Power Management version 2
Flags: PMEClk- DSI+ D1+ D2+ AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot-,D3cold-)
Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME-
Capabilities: [50] MSI: Enable- Count=1/1 Maskable- 64bit+
Address: 0000000000000000 Data: 0000
Kernel driver in use: snd_ctxfi

[tashirosgt]

The suggestion on the Fedora audio debugging page is to temporarily remove the pulseaudio plugin. If it (temporarily) fixes the problem then you know something about pulseaudio needs fixing instead of merely suspecting it.

[depierce]

Originally Posted by tashirosgt

The suggestion on the Fedora audio debugging page is to temporarily remove the pulseaudio plugin. If it (temporarily) fixes the problem then you know something about pulseaudio needs fixing instead of merely suspecting it.

Would you please link me the Fedora audio debugging page?

[tashirosgt]

http://fedoraproject.org/wiki/How_to...sound_problems

[Quantum]

I get exactly the same problem -a weird echoing/spazzing of audio after a period of time-- and I have a completely different audio card, I too run KDE, and this is on Debian not Fedora. I get it in MythTV while watching TV shows.

I suspect that rather than in a driver, this is caused by a higher-level function. I too don't know where to start; I've already removed most of Pulse.

[depierce]

Originally Posted by tashirosgt

http://fedoraproject.org/wiki/How_to...sound_problems

That page hasn't been touched since October '09. I ended up ripping out all pulseaudio* pkgs with the exception of pulseaudio-libs and -libs-glib2. I mean I tried removing those last two as well, but quickly discovered KDE expects those libs and dies without them (facepalm). Also switched phonon backend to use VLC (https://wirejungle.wordpress.com/201...-sound-in-kde/). After trying to beat it up by playing several flacs at once and streaming some youtube nonsense while generating KDE notification sounds on events - I can say it appears my problems are resolved.

Quantum, you might want to give what I did a shot. Can't hurt.

[Quantum]

I'd already done exactly that. I'll bet your problem comes back.

[tashirosgt]

I'm curious whether you notice anything different about the threads involved in audio processes when the sound problem happens - like a larger number of threads. The man page for "ps" says that "ps -eLf" and "ps axms" show information about threads, but I myself don't have any experience intrerpreting their output.

[Quantum]

I'll check it next time. I usually just bookmark the TV show, stop it, then restart and it's OK.