On Tue, Aug 9, 2011 at 6:17 PM, Stefan Kost <[email protected]> wrote:

> On 08/08/11 14:32, Nasa wrote:
> > Hi,
> >
> > Does anyone have any insight into the question asked by Col?
> > (See below).
> >
> > Thanks,
> >
> > Nasa
> > ----- Original Message -----
> >> 'Twas brillig, and Nasa at 07/08/11 21:26 did gyre and gimble:
> >>> Hi,
> >>>
> >>> I was hoping I could get some help troubleshooting some audio
> >>> quality issues I am running into.
> >>> Specifically, I am getting a lot of *pops/crackles* when I play
> >>> audio files. It shows up when I
> >>> move from 2-channel to 4/5 channel audio (via pauvcontrol) - I am
> >>> using a USB X-FI sound-card with
> >>> the Meego IVI.
> >>>
> >>> I have tried changing the resample method (going from ffmpeg to
> >>> high-quality) and setting tsched=0,
> >>> neither making any noticeable difference.
> >>>
> >>> The only things I saw in /var/log/messages that seemed relevant was:
> >>> messages:Aug 6 16:59:26 localhost pulseaudio[570]: alsa-sink.c: ALSA
> >>> woke us up to write new data to the device, but there was actually
> >>> nothing to write!
> >>> messages:Aug 6 16:59:26 localhost pulseaudio[570]: alsa-sink.c: Most
> >>> likely this is a bug in the ALSA driver 'snd_usb_audio'. Please
> >>> report this issue to the ALSA developers.
> >>> messages:Aug 6 16:59:26 localhost pulseaudio[570]: alsa-sink.c: We
> >>> were woken up with POLLOUT set -- however a subsequent
> >>> snd_pcm_avail() returned 0 or another value < min_avail.
> I would follow the advice and talk to the alsa devlopers. Ensure the
> driver is up-to-date.
>
> Stefan
> >>> And this was spout out of dmesg
> >>> [ 21.857184] ALSA sound/usb/mixer.c:2110: status interrupt: c0 00
> >>> [ 21.897058] ALSA sound/usb/mixer.c:2110: status interrupt: c0 00
> >>> [ 21.961062] ALSA sound/usb/mixer.c:2110: status interrupt: c0 00
> >>>
> >>> I have already eliminated the speakers and the amp (played music
> >>> from a different source and
> >>> they sounded fine).
> >>>
> >>> Let me know what else I should post (I could record the sound, if
> >>> that would be useful).
> >>>
> >>> Thanks in advance,
> >> While this could be an issue in the alsa driver itself, can I ask if
> >> you're applying any volume changes to your streams or sink?
> >>
> > I personally am not, however, the meego project maybe.  There are over
> > 250 patches against the base pulseaudio package (9.22) of which some
> > seem to have something to do with volume settings...
> >
> > 0249-bluetooth-Fix-HSP-volume-handling.patch
> > 0248-bluetooth-restore-original-sco_-sink-src-set_volume-.patch
> > 0247-bluetooth-fix-set_volume_cb-on-sco-over-pcm.patch
> > 0240-volume-proxy-small-lib-to-allow-communicating-volume.patch
> > 0224-pactl-Accept-more-volume-specification-formats.patch
> > 0223-sink-input-Add-volume_writable-to-pa_sink_input.patch
> > 0190-alsa-mixer-Refactoring-merge-element_mute_volume-ele.patch
> > 0189-alsa-mixer-Implement-constant-volume.patch
> > 0140-dbus-Always-accept-mono-volumes-when-setting-device-.patch
> > 0133-volume-Add-Orc-based-optimised-volume-scaling.patch
> > 0132-volume-Fix-sample-array-size-for-tests.patch
> > 0131-volume-Make-tests-use-only-valid-volumes.patch
> > 0130-alsa-mixer-Fix-a-git-am-cockup-in-b0f72311.patch
> > 0129-volume-Add-a-PA_VOLUME_UI_MAX-define-for-the-recomme.patch
> > 0124-introspect-Client-side-implementation-for-has_volume.patch
> > 0118-Revert-Add-volume-ramping-feature-envelop-fix.patch
> > 0117-Revert-Add-volume-ramping-feature-sink-input-modific.patch
> > 0116-Revert-Add-volume-ramping-feature-sink-modification.patch
> > 0114-Revert-core-volume-ramping-fix.patch
> > 0107-virtual-sink-Add-a-modarg-for-forcing-flat-volume.patch
> > 0106-virtual-sink-Add-a-modarg-for-enabling-volume-sharin.patch
> > 0105-Implement-the-volume-sharing-feature.patch
> > 0090-Allow-read-only-or-non-existing-sink-input-volume.patch
> > 0042-core-Use-volume_change_safety_margin-when-rewinding-.patch
> > 0022-volume-Trivial-cosmetics-remove-a-space.patch
> > 0011-alsa-sink-take-base-volume-into-account-when-applyin.patch
> > 0001-volume-Add-explicit-checks-for-ARMv6-instructions.patch
> > 0001-fix-the-assumption-that-volume-is-always-positive.patch
> >
> > So can see all the patches and what's in them here:
> >
> https://build.pub.meego.com/package/files?package=Pulseaudio&project=home%3Anasa
> > (not that I'm expecting and/or requesting you do that -- I just
> > put this here for reference)
> >
> > Nasa
> >
> > BTW: I will try your suggestion when I get home this evening.
> >
> >
> >> There could be a problem with optimized paths for software volume
> >> adjustments. You can disable these optimisations via a special
> >> environment var: PULSE_NO_SIMD=1
> >>
> >> It's worth checking this to see if it's that area that's at fault.
> >>
> >> Col
> >>
> >>
> > _______________________________________________
> > pulseaudio-discuss mailing list
> > [email protected]
> > http://lists.freedesktop.org/mailman/listinfo/pulseaudio-discuss
> > _______________________________________________
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>

I also faced similar kind of problem while using vlc player. After a lot of
head-banging in and around we found-out that vlc is using pulseaudio as its
aoudio backend and just to try out i replaced pulseaudio with alsa and
everything worked like magic. You can tryout this command 'vlc --aout alsa'
. If this works for you then u can make this change permanently in desktop
file present in '/usr/share/applications/' ( it would be either vlc.desktop
or livna-vlc.desktop ) . Just look for the 'Exec=[something]' line and
change it to 'Exec=vlc --aout alsa %U' . You will need to restart system
after making changes to desktop file.
Hope this helps.
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