On Wed, 2006-12-20 at 14:27 +0000, J M Needham wrote: > Ok, thanks Lars. I guess I'll be treating myself to an audiophile for > Christmas unless anyone's got a better idea. > These hardware constraints are defined in max/min bytes per period across all supported formats. So, to get lower latency, increase the channel count or sample rate. 64 frames at 44100Hz is ~1.45ms each way or 2.9ms (plus any hardware latency) round trip. At 48000Hz this would give 2.66ms, and at 96000Hz 1.33ms. Lee > > On Wed, 20 Dec 2006, Lars Luthman wrote: > > > On Wed, 2006-12-20 at 10:34 +0000, J M Needham wrote: > > > So I've just installed Ubuntu 6.09, and followed the instructions on > > > http://fort2.xdas.com/~kor/oss2jack/install.html to install the > > > realtime-lsm module and I've added > > > @audio - rtprio 80 > > > @audio - memlock 500000 > > > > > > to /etc/security/limits.conf and set the realtime mode on Jack. Seems ok, > > > the only thing is that I can't get below 5.8 ms latency. Jack's behaving > > > nicely with very few xruns, but won't do any better. The output of the > > > messages with 32 frames for capture, for example, is: > > > > > > 10:41:35.039 Startup script... > > > ... > > > configuring for 44100Hz, period = 32 frames, buffer = 2 periods > > > ALSA: cannot set period size to 32 frames for capture > > > ALSA: cannot configure capture channel > > > cannot load driver module alsa > > > > It looks like your hardware simply can't handle buffer sizes that small. > > > > > >
