jack_delay reporting latency different from measurement with ardour

Hi all,

I wanted to estimate the roundtrip latency of my soundcard to be able to provide correct I/O offset values for jack.

If I record an audio click track in ardour through a real cable loop back into ardour, I can observe an offset of ~60 frames, which I use to configure jacks input offset. This seems to produce a perfect alignment of new tracks with existing material.

In a first attempt I used jack_delay for latency estimation.
Jack_delay reported a latency of ~3131 frames.
If I subtract the software latency (1024 frames * 2 periods), the resulting hardware latency is 1083, which seems quite high for an m-audio audiophile.
This value cannot be correct.
Are there known issues with jack_delay?



My setup:
ardour 2.8
jack 1.9.5 at 44.1 khz with 1024 Frames, 2 Periods
M-AUDIO audiophile
linux kernel 2.6.34-12

3131 = 3 * 1024 + 59. I suspect you either do have 3 periods of latency, or you did connect jack_delay in a way that would add a period of latency to the measurement.