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

[Luis Garrido]

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 :(
>
>