I am using a Python API
(https://github.com/spatialaudio/jackclient-python) to instantiate JACK
clients in independent Python processes. With reasonable audio block
lengths (256 to 4096) it works very well to do pretty demanding
real-time signal processing tasks (just FYI and to understand the context).
The API allows me to detect occurring xruns with a reported signal
delay, coming from the JACK library. Sometimes xruns occur and the
reported delay is 0ms, while the audio stream clearly experiences a
dropout. I've also seen higher delays reported, but right now I cannot
tell under what conditions.
I just wonder how the delay times are gathered, how reliable or
conclusive they are in general and what an xrun "without delay" might mean?!