[pulseaudio-discuss] Need help to reduce delay with USB, mic using pulseaudio

[ashwanik]

On Friday 12 August 2011 12:30 AM, 
pulseaudio-discuss-request at lists.freedesktop.org wrote:
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> Today's Topics:
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>     1. Re: Pops/Crackles Messing up my audio... (Nasa)
>     2. Re: Need help to reduce delay with USB,	mic using pulseaudio
>        (Pierre-Louis Bossart)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Thu, 11 Aug 2011 17:09:25 +0000 (UTC)
> From: Nasa<nasa01 at comcast.net>
> Subject: Re: [pulseaudio-discuss] Pops/Crackles Messing up my audio...
> To: General PulseAudio Discussion
> 	<pulseaudio-discuss at lists.freedesktop.org>
> Cc: alsa-user at lists.sourceforge.net
> Message-ID:
> 	<294431320.552022.1313082565114.JavaMail.root at sz0115a.westchester.pa.mail.comcast.net>
> 	
> Content-Type: text/plain; charset=utf-8
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>
>
> ----- Original Message -----
>    
>> ----- 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.
>>>>
>>>> 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?
>>>
>>> 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
>>>        
>> Col,
>>
>> So I added
>>
>> export PULSE_NO_SIMD=1
>>
>> into my .bashrc file and rebooted. From the terminal
>> "echo $PULSE_NO_SIMD" came back '1' -- however, that didn't
>> make any difference in the pops/crackles I am hearing :{
>>
>> Nasa
>>
>>
>>      
> So,
>
> Is there anything else I can check, or should I place a bug report
> for ALSA?
>
> Nasa
>
>
> ------------------------------
>
> Message: 2
> Date: Thu, 11 Aug 2011 12:48:38 -0500
> From: "Pierre-Louis Bossart"<pierre-louis.bossart at linux.intel.com>
> Subject: Re: [pulseaudio-discuss] Need help to reduce delay with USB,
> 	mic using pulseaudio
> To: "'General PulseAudio Discussion'"
> 	<pulseaudio-discuss at lists.freedesktop.org>
> Message-ID:<007c01cc584e$e6bcfba0$b436f2e0$@bossart at linux.intel.com>
> Content-Type: text/plain;	charset="us-ascii"
>
>    
>>>> Use module-loopback and play with the latency parameters.
>>>>          
>>> In case you don't know what the latency parameters are, on the
>>> gst-launch line, you can append these parameters: e.g.
>>>
>>> gst-launch-0.10 pulsesrc buffer-time=<xxxx>  latency-time=<xxxx>  !
>>> pulsesink buffer-time=<xxxx>  latency-time=<xxxx>
>>>
>>>        
>> I suspect Pierre was referring to the latency_usec param on module-
>> loopback.
>>      
> Correct. Providing data to a client and back isn't the most efficient thing
> to do if you can handle this in IO threads.
>
>
>
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> End of pulseaudio-discuss Digest, Vol 4, Issue 32
> *************************************************
>    
What is module-loopback?

I changed buffer-time and latency-time for different values in 
gst-pieline but no success. It reduces delay very less amount i.e delay 
is still there
(2-2.5 sec).

When I use alsasrc and alsasink with the same usb mic getting no delay 
with good audio quality.

Please help to solve the problem.

Regards
Ashwani