Sound recording and latency...
 

Hello folks,

I've been setting up a Linux box for my dad, as below-

SuSE 8.2
Athlon XP 3000+
MSI KT6 Delta (SuSE kernel patched to include VIA southbridge drivers)
512MB DDR
ATI Radeon 9200

For the most part the system is now working well. However, one of my dad's real interests is recording his old vinyl LPs and transferring to CD....

Now, I also use SuSE 8.2 and I've had problems in the past with choppy sound as a result of latency. It's not such a problem with playback (in fact, with XMMS and nothing else running, all is fine), but clearly, an absolute show-stopper when it comes to recording.

Using qarecord on my dad's machine, I recorded a small, 1 minute, passage of music - having made sure first that I had no other unnecessary tasks running. The results were rather poor - the were numerous drop-outs and jumps..

So has anybody got any ideas of what the options are? The low-latency patches are out, because the SuSE 2.4.20 kernel is heavily modified by SuSE and I can't get the patch to work. I did hear that the SuSE kernel already had the low latency stuff in there, but from my experience, I don't think so!!

Both my dad and I would love to sort this out - at the moment he's having to use win xp to record / process audio...

thanks in anticipation of any help.

cheers,

Kevin.

Is there any particular reason you can't go with a plain vanilla kernel from kernel.org and apply the lowlatency and preemptive kernel patches? That would be my route. Also make sure the audio driver module is loaded with the correct parameters. These two patches combined enhance latency a *lot* and IMHO it's virtually impossible to use apps like Ardour without them.


Håkan

hi hw-tph,

thanks for your reply;

.. yes, I think that's what I'll be looking to do. Having done some more web research this lunchtime, it would appear that the SuSE 2.4.20 kernel does indeed include most of the low-latency code; however, the preemptive stuff has not been applied..

so i'll be heading over to kernel.org... but first, please could you clarify something -

i assume i should be looking in modules.conf to examine parameters; and if so, what should i look for, or is it a case of locating information specific to my soundcard (ac97 on-board sound)?

sorry, i'm not in front of the linux box at the moment (at work) but i'll set to with the kernel stuff when i get home.

thanks again for your help on this - it's appreciated.

Yes, you should be setting the module parameters in /etc/modules.conf unless you are going to load the module manually each time (not very probable).

To see what options/parameters your audio module supports, type modinfo <modulename> as root (you would type modinfo cmpci if you have a CMI8378 soundcard). These are the options you then can use in modules.conf.


Håkan