[LAU] pops & clicks

[Pieter Palmers]

verymeta at riseup.net wrote:
> Pops and clicks
> 
> I was wondering if anyone on this list has any ideas what might be causing
> the pops and clicks I'm getting. I'm running Ubuntu Gutsy with realtime
> kernel, and using an M-Audio Firewire Solo audio interface. I'm creating
> audio by running quite a few amSynths through Seq24.
> 
> There are actually two kinds of noise that I'm getting: the first is a
> click that happens with certain bass tracks, where the bass cuts out quite
> abruptly. I get a click with each note - needless to say it sounds awful.
> I can get rid of this by making the notes die off a little more gradually
> but obviously I'd rather not have to do this.
> 
> I also get random pops and clicks, and sometimes the audio just cuts out
> for a moment. This _terrible_ since the clicks are sometimes much louder
> than the song I'm trying to play. If I used a big amp/speakers, I would
> blow them :-(
> 
> Jack doesn't report any problems in the messages window. I can turn my
> latency down to around 2msec or up to 67msec or higher, but this seems to
> have no effects on the pops and clicks. No xruns are reported.

I assume you are using freebob and not ffado.
Some things to check:
* are you running jackd with the realtime flag?
* do you alleviate the priority of the ohci1394 interrupt above other 
interrupt sources? (e.g. with the rtirq)
* does dmesg show anything special regarding 1394?
* what firewire chipset do you use? (lspci | grep 1394)
* are you using -n3 (to specify the usage of 3 buffers of one period)?

Greets,

Pieter