[linux-audio-dev] Re: the big jack bug... > crappy audio on XRUNS - Linux-audio-dev

6 Nov 2005

Hi!

I had a similar problem in my laptop when using a USB soundcard
(Edirol UA-25). For me it was not necessarily associated with xruns.

Since ardour doesn't record the noise, I would say that the problem is
not in jack, but in the alsa driver.

It sounded also more like a distortion than noise, since when the
output levels were low the effect was less noticeable.

I found empirically that harddisk writing operations like saving a
file in an application would sometimes make the distortion stop, I'll
be damned if I know why (interrupts?).

Anyway, setting my USB unit to work at 48 kHz made this problem
practically disappear.

HTH,

Luis

...
  it happens randomly, while I play a soft synth, that
jack XRUNs once,
 and the audio become crappy, noisy, like a kinda of digital
 effect....bit crusher?

 then all synthesizers (all audio apps) sound the same sh*t...
 i tried recording with ardour the output, and the output is clean, so I
 guess is a problem of sync or something that has to do with the hardware
 (soundcard).

 in order to record this noise, i had to connect the soundcard output in
 its input and record it via analog in:
 http://xaero.ath.cx/jackbug_stereo.wav.bz2 (it is a stereo file, with
 the clean track panned on the left, and the dirty one on the right).

 i hope it could be useful to debug the problem...
 what other information I can provide useful for debug?
 note that this happens with many version of alsa (1.0.9b, 1.0.10rc2,
 1.0.7 or less) and with many kernels (gentoo-sources (slightly patched
 for speed improvement), ck-sources, ck-sources+realtime-lsm)

 i hope to solve this problem, since my audio desktop is unusable as si,
 since audio crasher after playng for just 5 minutes :(