[pulseaudio-discuss] crackle and stutter

Brian J. Murrell brian at interlinx.bc.ca
Tue Apr 12 09:24:48 PDT 2011 

On 11-04-12 12:00 PM, Sean McNamara wrote:
> Hi,

Hi,

> Can you give an example of what application(s) in particular trigger
> this?

Skype for example, when somebody sends an IM, or logs on.  Skype pops up
a notification and emits a sound event.  Or when I generate a keyboard
sound event, like hitting tab a bunch of times at a bash prompt.  It
displays:

Display all 5014 possibilities? (y or n)

For example, and each tab emits a sound event.  If I hit tab a good
number of times I can see this in PA:

D: core-scache.c: Playing sample "bell-window-system" on
"alsa_output.pci-0000_00_10.1.analog-stereo"
D: memblockq.c: memblockq requested: maxlength=17640, tlength=0, base=2,
prebuf=1, minreq=1 maxrewind=0
D: memblockq.c: memblockq sanitized: maxlength=17640, tlength=17640,
base=2, prebuf=2, minreq=2 maxrewind=0
D: module-stream-restore.c: Not restoring device for stream
sink-input-by-media-role:event, because already set to
'alsa_output.pci-0000_00_10.1.analog-stereo'.
D: module-intended-roles.c: Not setting device for stream
bell-window-system, because already set.
I: module-stream-restore.c: Restoring volume for sink input
sink-input-by-media-role:event.
I: module-stream-restore.c: Restoring mute state for sink input
sink-input-by-media-role:event.
D: module-suspend-on-idle.c: Sink
alsa_output.pci-0000_00_10.1.analog-stereo becomes busy.
I: resampler.c: Forcing resampler 'copy', because of fixed, identical
sample rates.
D: resampler.c: Channel matrix:
D: resampler.c:        I00
D: resampler.c:     +------
D: resampler.c: O00 | 1.000
D: resampler.c: O01 | 1.000
I: remap_sse.c: Using SSE mono to stereo remapping
I: resampler.c: Using resampler 'copy'
I: resampler.c: Using s16le as working format.
D: memblockq.c: memblockq requested: maxlength=33554432, tlength=0,
base=4, prebuf=0, minreq=1 maxrewind=0
D: memblockq.c: memblockq sanitized: maxlength=33554432,
tlength=33554432, base=4, prebuf=0, minreq=4 maxrewind=0
I: sink-input.c: Created input 6004 "bell-window-system" on
alsa_output.pci-0000_00_10.1.analog-stereo with sample spec s16le 1ch
44100Hz and channel map mono
I: sink-input.c:     media.name = "bell-window-system"
I: sink-input.c:     event.id = "bell-window-system"
I: sink-input.c:     media.role = "event"
I: sink-input.c:     application.process.id = "3904"
I: sink-input.c:     application.name = "gnome-terminal"
I: sink-input.c:     event.description = "Bell event"
I: sink-input.c:     media.filename =
"/usr/share//sounds/ubuntu/stereo/bell.ogg"
I: sink-input.c:     native-protocol.peer = "UNIX socket client"
I: sink-input.c:     native-protocol.version = "16"
I: sink-input.c:     window.x11.display = ":0.0"
I: sink-input.c:     window.x11.screen = "0"
I: sink-input.c:     application.process.user = "brian"
I: sink-input.c:     application.process.host = "pc"
I: sink-input.c:     application.process.binary = "metacity"
I: sink-input.c:     application.language = "en_CA.UTF-8"
I: sink-input.c:     application.process.machine_id =
"c5af5645621daea8981bd8ac95e82500"
I: sink-input.c:     application.process.session_id =
"c5af5645621daea8981bd8ac95e82500-1301933908.840922-406521422"
I: sink-input.c:     window.x11.xid = "48333716"
I: sink-input.c:     window.name = "pc:/etc/shorewall6/gw-new"
I: sink-input.c:     module-stream-restore.id =
"sink-input-by-media-role:event"
D: core-util.c: posix_madvise() worked fine!
D: alsa-sink.c: Requested to rewind 352768 bytes.
D: alsa-sink.c: Limited to 21016 bytes.
D: alsa-sink.c: before: 5254
D: alsa-sink.c: after: 5254
D: alsa-sink.c: Rewound 21016 bytes.
D: sink.c: Processing rewind...
D: sink-input.c: Have to rewind 21016 bytes on render memblockq.
D: sink-input.c: Have to rewind 21016 bytes on render memblockq.
D: sink-input.c: Have to rewind 21016 bytes on render memblockq.
D: sink-input.c: Have to rewind 21016 bytes on render memblockq.
D: sink-input.c: Have to rewind 21016 bytes on render memblockq.
D: sink-input.c: Have to rewind 21016 bytes on render memblockq.
D: sink-input.c: Have to rewind 21016 bytes on render memblockq.
D: sink-input.c: Have to rewind 21016 bytes on render memblockq.
D: sink-input.c: Have to rewind 21016 bytes on render memblockq.
D: sink-input.c: Have to rewind 21016 bytes on render memblockq.
D: sink-input.c: Have to rewind 21016 bytes on render memblockq.
D: sink-input.c: Have to rewind 21016 bytes on render memblockq.
D: sink-input.c: Have to rewind 21016 bytes on render memblockq.
D: sink-input.c: Have to rewind 21016 bytes on render memblockq.
D: sink-input.c: Have to rewind 21016 bytes on render memblockq.
D: sink-input.c: Have to rewind 21016 bytes on render memblockq.
D: sink-input.c: Have to rewind 21016 bytes on render memblockq.
D: source.c: Processing rewind...
D: alsa-sink.c: Latency set to 136.00ms
D: alsa-sink.c: hwbuf_unused=328780
D: alsa-sink.c: setting avail_min=83952
D: alsa-sink.c: Requested to rewind 352768 bytes.
D: alsa-sink.c: Limited to 23660 bytes.
D: alsa-sink.c: before: 5915
D: alsa-sink.c: after: 5915
D: alsa-sink.c: Rewound 23660 bytes.
I: sink-input.c: Freeing input 5988 "bell-window-system"
D: sink.c: Processing rewind...
D: sink-input.c: Have to rewind 23660 bytes on render memblockq.
D: sink-input.c: Have to rewind 23660 bytes on render memblockq.
D: sink-input.c: Have to rewind 23660 bytes on render memblockq.
D: sink-input.c: Have to rewind 23660 bytes on render memblockq.
D: sink-input.c: Have to rewind 23660 bytes on render memblockq.
D: sink-input.c: Have to rewind 23660 bytes on render memblockq.
D: sink-input.c: Have to rewind 23660 bytes on render memblockq.
D: sink-input.c: Have to rewind 23660 bytes on render memblockq.
D: sink-input.c: Have to rewind 23660 bytes on render memblockq.
D: sink-input.c: Have to rewind 23660 bytes on render memblockq.
D: sink-input.c: Have to rewind 23660 bytes on render memblockq.
D: sink-input.c: Have to rewind 23660 bytes on render memblockq.
D: sink-input.c: Have to rewind 23660 bytes on render memblockq.
D: sink-input.c: Have to rewind 23660 bytes on render memblockq.
D: sink-input.c: Have to rewind 23660 bytes on render memblockq.
D: sink-input.c: Have to rewind 23660 bytes on render memblockq.
D: sink-input.c: Have to rewind 23660 bytes on render memblockq.
D: source.c: Processing rewind...

> Is it reproducible 100% of the time, or just sometimes?

When it starts happening, it's quite reproducible.  My recollection
however is that it takes some time for the PA server to get into this state.

> How is
> your CPU load when this is occurring?

Negligible.

> Some amount of rewinds are normal. Especially when the server first
> starts up, or when the amount of latency demanded by an application is
> very low while system load is high.

Well, this PA server has been up since April 5 and the only applications
actively using it are rhythmbox and a few apps which want to send
notifications, like skype and pidgin.  I don't think any of that should
necessarily be "low latency" demanding applications.

> But excessive rewinds can be due
> to a driver bug in ALSA (this would have to be specific to your
> hardware since I can't reproduce the issue here on Maverick). I like
> to compare it to an anti-lock break system: if it engages at the right
> time, it's useful, but if it engages erroneously it can be dangerous.

I seem to get these rewinds with every single notification sound that
Skype sends.

> Also (back to addressing Brian), it's always useful to post the output
> of running alsa-info.sh with problems like this:
> http://git.alsa-project.org/?p=alsa-driver.git;a=blob_plain;f=utils/alsa-info.sh

http://brian.interlinx.bc.ca/alsa-info.txt.wI2YqOw8Nv

> I can't speak to the Ubuntu SRU process, but it's quite possible that
> a stable update fixing this issue for Maverick will never arrive
> (especially if nobody gets to the bottom of the issue). Your
> alternatives are to try Natty (it's stabilizing well in Beta 2-ish
> now), another more recent distro, or stay where you are but compile
> PulseAudio from git (stable-queue branch is a good choice). The
> problem might already be fixed upstream.

Yeah, or there is
https://launchpad.net/~ubuntu-audio-dev/+archive/ppa/+packages but I
wanted to see if the problem is known and actually fixed there before I
do that.  As an aside, I have to say, I find it frustrating that with
*every* *single* Ubuntu release I have to use that repo to get decent
sound.  :-(

> As a last-ditch workaround you might try disabling time-based
> scheduling, but troubleshooting further first would be preferred :)
> With a bit more work, a fix could be forthcoming, and then we could
> resolve the issue for everyone who has your particular (or shall I
> say, peculiar?) sound chipset.

Yeah.  I definitely like to contribute if I can.  I wonder where, if
anywhere, I can find David's work on this.

Cheers, and thanx much for the input!

b.

-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 262 bytes
Desc: OpenPGP digital signature
URL: <http://lists.freedesktop.org/archives/pulseaudio-discuss/attachments/20110412/f6d325ea/attachment.pgp>

More information about the pulseaudio-discuss mailing list