[LAU] Finding the delay/latency of a Zoom

[Ken Restivo]

On Tue, Mar 16, 2010 at 11:25:25PM +0100, fons at kokkinizita.net wrote:
> On Tue, Mar 16, 2010 at 02:31:29PM -0700, Ken Restivo wrote:
> 
> > Any ideas how to measure latency on this thing a "manual" way, not using Fons's tool, and given that there's no way to turn off monitoring, so I can't just pipe the line out into the line in as a loop without getting some awful digital feedback.
> 
> If the monitoring is stereo (L->L, R->R), you could try to
> connect line-out-L to line-in-R, then use out-L and in-R
> with jack_delay.
> 

Genius. That's exactly the kind of solution I was hoping for. Thank you very much!  I'll try that.

> If the latency is really 'seconds' it will be above
> jack_delay's ambiguitiy interval which is 2^16 samples.
> In that case you'd have to add some integer times 2^16
> samples to the measurement to get the real delay.
> 

My back-of-the-envelope calculation, done by manually moving a percussion track in Ardour until it sync'ed up with the drumkit, and then noting the difference in the region start times, is that the latency through the Zoom is either exactly two seconds, or Ardour's region start time resolution doesn't go to fractions of seconds.

I'll try that trick with jack_delay and see how far I get with that.

Thanks again.

-ken