[linux-audio-user] Again on sudden and occasional Jack crackling sound

[Florian Schmidt]

On Tue, 09 Aug 2005 22:17:04 +0000
Salvatore Di Pietro <salvuz_78 at virgilio.it> wrote:

> Moreover, using jack_bufsize, or resizing buffer within Ardour, causes 
> complete muting of output sound (bit not clients death, as it was 
> before), until I restart jack.
> Notice that this "complete muting" only affects the output ports, i.e. I 
> can continue recording with qarecord, or ardour, I just cannot hear (and 
> monitor) anything anymore until I restart jack and its clients.
> Also the crackling problem only affects the output ports, as I pointed 
> out in the first post (and on jackit-devel)
> 
> What other tests can I do?
> Thank you

I wonder: Other sound apps don't produce the crackling i'd reckon. Maybe
it's related to the periodsize/periodcount setting used. Maybe try
running jackd with a buffer of 1024 and more than 4 periods.

Or try a different sound app with 128/2. 

I wonder what the crackling could be caused by? Is it some sort of
corruption in the buffers that jack passes to the soundcard? if so, it
would be nice to have the content of some buffers after the crackling
started (maybe a crude memory dump could work. If it kills realtime - so
what. the first buffer which is output to the terminal might be enough
if you feed jack some simple sine signal [maybe use om or supercollider
or some other jackable test tone generator].

At least we could make the are to look for bugs smaller. If the crackles
are in the buffers already, it's a jack IPC thing, if it's not in the
buffers, it might be either a problem of how jack operates the soundcard
or with the soundcard driver/soundcard itself..

Regards,
Flo

-- 
Palimm Palimm!
http://tapas.affenbande.org