linuxaudio.org

Levi Burton  writes:
> I looked at jackd options, maybe someone could explain what they do for me:

quoted text
>

>  1.  -p,--period      frames per period (default: 1024)

>  2.  -n,--nperiods    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