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List:       meego-dev
Subject:    Re: [MeeGo-dev] Fwd: [pulseaudio-discuss] [Alsa-user] Pops/Crackles
From:       Stefan Kost <ensonic () hora-obscura ! de>
Date:       2011-08-09 12:47:57
Message-ID: 4E412C7D.60903 () hora-obscura ! de
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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
>>
>>
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