# ALC662 audio card causes underruns and overruns

**URL:** <https://www.ruby-forum.com/t/alc662-audio-card-causes-underruns-and-overruns/243166>\
**Category:** GNU Radio\
**Created:** [August 28, 2015, 10:42am UTC](https://www.ruby-forum.com/t/alc662-audio-card-causes-underruns-and-overruns/243166 "2015-08-28T10:42:22Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Sadaf\_N](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/858c86/32.png) [@Sadaf\_N](https://www.ruby-forum.com/u/Sadaf_N)\
**Post date:** [August 28, 2015, 10:42am UTC](https://www.ruby-forum.com/t/alc662-audio-card-causes-underruns-and-overruns/243166/1 "2015-08-28T10:42:22Z")

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Hi,

I have a flow graph that receives, demodulates and filters a signal  
before  
sending it to the audio card. It’s been working in a single board,  
single  
core, computer with an audio card ALC888 for months. I occasionally had  
underrun messages, specially when changing filter parameters. This  
messages  
were normally less than 10 and very spread, about every 30 seconds. It  
didn’t cause any noticeable noise or problems.

Recently I moved to a better computer with better CPU, 4 cores and a  
ALC662  
audio card. The Python script works fine, with no visible bottlenecks in  
the processor. However, I now get constant overruns and underruns  
reported,  
making the audio noisy.  
The audio card is able to work correctly when using the speaker-test  
command so, there isn’t a fault in the hardware. It’s also capable of  
running at the required sample rate.

Is there any test I could make to understand and fix this issue? Has  
anyone  
had a bad experience using this audio card with GnuRadio?

Thanks,  
Murray

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**Author:** ![Murray\_T](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/3bc359/32.png) [@Murray\_T](https://www.ruby-forum.com/u/Murray_T)\
**Post date:** [August 28, 2015, 12:32pm UTC](https://www.ruby-forum.com/t/alc662-audio-card-causes-underruns-and-overruns/243166/2 "2015-08-28T12:32:11Z")

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Make sure you’re using ‘plughw:’ for the audio device so the driver does  
resampling (check ALSA docs). Without looking at the flowgraph, I’d  
guess this is a clock domain problem and your new computer (and audio  
card) clocks are somehow different than your old ones.

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**Author:** ![Murray\_T](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/3bc359/32.png) [@Murray\_T](https://www.ruby-forum.com/u/Murray_T)\
**Post date:** [August 28, 2015, 2:54pm UTC](https://www.ruby-forum.com/t/alc662-audio-card-causes-underruns-and-overruns/243166/3 "2015-08-28T14:54:08Z")

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Also make sure that the ALC662 also supports the audio sampling rate  
you’re using – 44100 is the only rate I’ve been able to use on any  
platform [1].

Best regards,  
Marcus

[1] [http://gnuradio.org/redmine/projects/gnuradio/wiki/ALSAPulseAudio](http://gnuradio.org/redmine/projects/gnuradio/wiki/ALSAPulseAudio)

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**Author:** ![Murray\_T](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/3bc359/32.png) [@Murray\_T](https://www.ruby-forum.com/u/Murray_T)\
**Post date:** [August 28, 2015, 3:11pm UTC](https://www.ruby-forum.com/t/alc662-audio-card-causes-underruns-and-overruns/243166/4 "2015-08-28T15:11:05Z")

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Thank you for your suggestions.  
The card supports 96 KHz and I’m using hw. I’ll try to use plughw.  
I’ve solved this problem upgrading to the latest kernel in 12.04 which  
is  
3.13.0-62.

Regards,  
Murray

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<div class="post-metadata">

**Author:** ![Murray\_T](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/3bc359/32.png) [@Murray\_T](https://www.ruby-forum.com/u/Murray_T)\
**Post date:** [August 28, 2015, 3:37pm UTC](https://www.ruby-forum.com/t/alc662-audio-card-causes-underruns-and-overruns/243166/5 "2015-08-28T15:37:22Z")

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Wow, 12.04 (though still supported by GNU Radio!) feels ancient. Any  
particular reason you stick with that?