On Fri, 2013-12-20 at 12:50 +0100, Jeremy Jongepier wrote:
> On 20-12-13 12:48, Ralf Mardorf wrote:
> > On Fri, 2013-12-20 at 11:22 +0000, Fons Adriaensen wrote:
> >> On Fri, Dec 20, 2013 at 11:19:22AM +0100, Ralf Mardorf wrote:
> >>>
> >>> -n3 should only be used, if -n2 shouldn't work. AFAIK -n3 will increase
> >>> jitter, so the sound could become muddy.
> >>
> >> Please stop spreading such nonsense. Jitter depends on the stability
> >> of the AD/DA converters clock, and nothing else.
> >
> > I never tested it myself, however, I remember that it often is mentioned
> > not to use -n >2. Is there a reason to avoid -n >2 or is t juts a myth?
> >
> man jackd
This doesn't answer my question [1], resp. IIUC there is _no_ drawback
when using -n >2, if there would be a drawback, it would have been
mentioned in the man page?!
OTOH the default rate is 48000 Hz and for good reasons it definitive is
the rate used for studio productions, but there's no hint not to use
rates < 48000 Hz ;).
It would be nice if you would share information, I guess this is what
lists are for, it's not a battle ;).
Unlikely that the Arch jackd manual page is incomplete, but I can't find
further info there.
[1]
ALSA BACKEND OPTIONS
-n, --nperiods int
Specify the number of periods of playback latency. In seconds, this corresponds to --nperiods
times --period divided by --rate. The default is 2, the minimum allowable. For most devices,
there is no need for any other value with the --realtime option. Without realtime privileges or
with boards providing unreliable interrupts (like ymfpci), a larger value may yield fewer xruns.
This can also help if the system is not tuned for reliable realtime scheduling.
For most ALSA devices, the hardware buffer has exactly --period times --nperiods frames. Some
devices demand a larger buffer. If so, JACK will use the smallest possible buffer containing at
least --nperiods, but the playback latency does not increase.
For USB audio devices it is recommended to use -n 3. Firewire devices supported by FFADO (for‐
merly Freebob) are configured with -n 3 by default.
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