Horrible unhandled latency -- only while recording?
Hi all. I'm using a Presonus Firepod connected to a Thinkpad A31p (1.7 ghz P4) w/a Seagate 7200 RPM drive (it's pretty much as fast as a laptop drive gets).
Here's my problem, which has been vexing me for a couple months now. When I'm _not_ recording, latency is fine. Jack reports 11 ms, I believe, which is fine with me. Listening to software monitoring only, everything is fine (and I'm positive that the audio is getting to Ardour, as panning/faders work on what I'm monitoring). Until I start actually recording. At that point, latency becomes about 200ms (unacceptable, basically), and after recording anything, I have to scoot everything I just recorded forward. It's very frustrating and difficult to get anything done, especially because I can't really jog tracks around well enough with my Tranzport, so listening to a drum track after I recorded it takes a good chunk of time.
Jackd is running realtime, all my IRQ priorities are set (and I've dicked around with them a bunch), 2.6.19 with Ingo's RT patches, etc etc. If it's in any documentation that Google can find, I've tried it. I don't believe it's a FreeBob/Firepod issue, as everything works _fine_ while not recording (just as much audio is going in and out). I don't believe it's a disk issue, as the latency doesn't seem to change if I'm recording a single mono track, or 6 tracks at once. I played with the Jack->Latency menu, but it doesn't seem to affect anything whether I set it to 32 or 4096.
ANY ideas? Here's two things I have yet to do:
A> Stick a 'loopback' in and see exactly how long the latency is
B> Try other recording software (rosegarden, etc) to see if it's just an Ardour thing.
I'm fine with using hardware monitoring. Really, if I could just somehow tell Ardour "There's going to be X ms of latency, so scoot everything forward automatically", I'd be fine.