4 Mar
2003
4 Mar
'03
12:33 a.m.
Levi Burton <donburton(a)sbcglobal.net> writes:
I looked at jackd options, maybe someone could explain
what they do for me:
1. -p,--period <n> frames per period (default: 1024)
2. -n,--nperiods <n> number of periods in hardware buffer (default: 2)
3. -H,--hwmon use hardware monitoring, if available (default: no)
4. -s,--softmode soft-mode, no xrun handling (default: off)
I'll try. Someone please correct me if I get any of this wrong.
-p sets the number of frames between JACK process() calls. This
must be a power of two (IIRC).
-n is the number of such periods in the buffer. P*N*4 is the size
of the JACK buffer in bytes. Larger buffers yield higher latency,
but fewer xruns.
If you need low latency, set -p and -n as low as you can without xrun
problems. Reasonably well-tuned current-generation systems with a
decent sound card and JACK running --realtime on a low-latency kernel
can handle -p 128 -n 3 reliably. Some can do better. Tuning a system
for low latency is challenging.
If you don't need low latency, set -p and -n higher to insulate
yourself from xruns.
-H tells JACK that your sound card provides capture input
monitoring.
-s tells JACK's ignore xruns reported by the ALSA driver. This
makes JACK less likely to disconnect ports when running without
--realtime.
--
Jack O'Quin
Austin, Texas, USA