Martin Homuth-Rosemann wrote: > don't know where I found this on the net that setting the buffer size > for usb audio a multiple of 1 ms duration, e.g. for 48000 kHz p=48 will > allow very low latencies. I tried this today with the latest rt kernel > and the cheap burr brown usb codec pcm2902 used in my behringer uca202: > > options snd_usb_audio nrpacks=1 You don't need this option; the driver was fixed to use sensible values years ago. > /usr/bin/jackd -R -P79 -dalsa -dhw:1,0 -r48000 -p48 -n2 -Xseq > > It runs smoothly on a centrino laptop (pentium M, cpu freq stepping > between 0.6 and 1.6 GHz). > > Maybe some of the jack and usb gurus (Paul?, Clemens?) can confirm the > -p48 -n2 setting. For most USB audio devices, using period sizes that are an integer multiple to the USB packet size (1 ms) will definitely help. Some devices like the SB Audigy 2 NX or UA-101 do not synchronize their sample clock to the USB clock (and this has nothing to do with USB 2.0), and in those cases, the period size does not matter. (I did not know that Jack now supports lengths that are not powers of two.) Best regards, Clemens _______________________________________________ Linux-audio-user mailing list Linux-audio-user@xxxxxxxxxxxxxxxxxxxx http://lists.linuxaudio.org/listinfo/linux-audio-user
