[ardour-users] Latency problem? Dropouts in WAV export

[Wolfgang Woehl]

Saturday 03 June 2006 00:40, Peter Maffay:

> I am really embarrassed for bothering you all -

Oh please don't be. Everyone's learning

> ofcourse the problem was this weird xmms, which
> obviously needs much more time for just playing a
> single 16-bit file then for ardour to mix it down
> on-the-fly...(!!!)

2 different ballparks: Usually jack makes sure that the backend (like alsa) 
gets its audio data in regular time intervals. That is a hard demand from the 
sound hardware (translated into the backends). If the soundcard doesn't get 
data in time you will hear dropouts (xruns). But jack has a mechanism to 
detach itself from these timing demands which is called "freewheeling". When 
you tell ardour to export it makes jack go freewheeling mode. This allows 
jack clients (ardour) to do their thing independent of the real-world time 
axis. So your xmms is locked in time to your sound hardware whereas the 
ardour *export* is not.

	<--------	in and out	locked in time	------------------>
				alsa backend to
sound hardware		netjack backend to				ardour
(needs data in		portaudio backend to	------	jackd		xmms
fixed intervals)		freebob backend to		|		other jack clients
				oss backend to			|
									|
								freewheeling
							not locked in time
							write to files or whatever

-- 
Wolfgang