[Ardour-Users] jack sample rate

[John Rigg]

On Mon, Apr 21, 2008 at 12:39:49AM +0100, John Rigg wrote:
> On Mon, Apr 07, 2008 at 11:14:29AM +0100, John Rigg wrote:
> > On Mon, Apr 07, 2008 at 09:13:39AM +0200, DA. Forsyth wrote:
> > > secondly I must be missing some setting somewhere as every project comes 
> > > up as 48000 sample rate.   I start jack using qjackctl and set it to 
> > > 44100, I use envy24control to set the Delta1010LT to 44100 (any order).
> > > 
> > > Now I start Ardour and it shows the sample rate as 48000, envy24control 
> > > shows the hardware has been changed, and jack becomes confused and exits.
> > > Surely Ardour sohudl take the setting from the hardware/jack, rather than 
> > > changing it?
> 
> It appears that the current version of envy24control is broken.
> I've just tested alsa-lib-1.0.16 with envy24control from
> alsa-tools-1.0.16 and it is behaving strangely. 
> It doesn't show the correct sample rate as set by jackd,
> and doesn't switch between S/PDIF and internal clocks correctly.
> I've tried it with 2.6.20 and 2.6.25 kernels and it's the same
> with both. I'll report it on the alsa-devel list.

Please disregard that last message. That's what happens when
testing software at 1:00am. envy24control does some strange things
if you try to alter clock sample rate or clock source while
jackd is running. The sample rate buttons do not necessarily
indicate what the actual sample rate is but the "Actual Rate"
window does appear to work. Sample rates and clock source
settings should not be changed in envy24control while jackd is
running.

If you set your Delta 1010LT initially to 44100 and Ardour then shows
48000 when it starts, it means that jackd was started with sample rate
set to 48000. This will change the sample rate of the card to 48000.
If you actually want to use 44100, jackd needs to be started with
-r44100 option. It defaults to 48000 if -r is not specified.
If jackd "gets confused" and exits, the problem is likely something
else.

John