Difference between revisions of "Garbled audio, alsa error 32: Broken pipe, Xrun errors"

Latest revision as of 15:39, 12 March 2018

Symptoms and environment

• Garbled audio
• No realtime kernel
• ALSA used
• Ubuntu 8.04
• Rivendell CVS version (November 2008)
• Flood of errors in in /var/log/messages:

 caed: *** alsa error 32: Broken pipe
 caed: ****** ALSA Playout Xrun - Card: 0 ******
 caed: ****** ALSA Capture Xrun - Card: 0 ******
 caed: *** alsa error 32: Broken pipe
 caed: ****** ALSA Playout Xrun - Card: 0 ******
 caed: *** alsa error 32: Broken pipe
 caed: ****** ALSA Playout Xrun - Card: 0 ******
 caed: ****** ALSA Capture Xrun - Card: 0 ******
 caed: *** alsa error 32: Broken pipe
 caed: ****** ALSA Playout Xrun - Card: 0 ******
 caed: period size mismatch - wrote 48 
 caed: ****** ALSA Playout Xrun - Card: 0 ******
 caed: *** alsa error 32: Broken pipe
 caed: ****** ALSA Playout Xrun - Card: 0 ******
 caed: ****** ALSA Capture Xrun - Card: 0 ******
 caed: period size mismatch - wrote 8 

Cause

Default buffer sizes for ALSA are too small in a standard kernel.

Quote:

 An overrun (also called xrun) occurs when the application doesn't read the
 opened audio device (i.e. "/dev/dsp") for a short time, causing the input
 buffer of the driver to run full.

Workaround

• Increase the ALSA buffer in /etc/rd.conf. Add the section:

 [Alsa]
 ; ALSA Parameters
 ; (It should seldom be necessary to tweak these)
 PeriodQuantity=4
 PeriodSize=1024

(Defaults are PeriodQuantity=2, PeriodSize=1024)

• Restart rivendell

This solved the problem for me.. Note that increasing buffers may increase the latency; but audio is okay again.

More Information

For more info also see Wiki page: Fine tuning ALSA for your sound card