[LAU] Testing JACK and PA latency

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To: linux-audio-user <linux-audio-user@...>
Date: Thursday, September 19, 2013 - 8:46 am

Moving this thread to LAU as it seems to be a more generic issue now:

I am testing the round trip latency when using PA and JACK together. I
have the following connection graph:

jack_system (in) -> pa_source (in) -> audacity (in) -> audacity (out) ->
pa sink (out) -> jack_system (out)

Audacity is run in pass through mode with internal latency set to 0.

I would like to measure the round trip latency from jack_system (in) to
jack_system (out)

This is a slightly unusual request but it is actually a reasonably
important measurement in the bigger scheme of things.

Does anyone have any suggestions?

Ideally I would like to get accurate measurements for both input and
output latency.

input:
jack_system (in) -> pa_source (in) -> audacity (in)

output:
audacity (out) -> pa sink (out) -> jack_system (out)

So a tool that allowed me to measure the latency between every node on the
graph would be perfect.

Obviously made alot harder by mixing PA and JACK together. I have tried
jack_iodelay but it does not measure the input signal from the mic instead
it provides it's own signal.

I suppose I could modify jack_iodelay to accept an input signal as the
starting point for the latency graph but I have not looked into the code
yet to see how tricky that would be.

--
Patrick Shirkey
Boost Hardware Ltd
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Messages in current thread:
[LAU] Testing JACK and PA latency, Patrick Shirkey, (Thu Sep 19, 8:46 am)
Re: [LAU] Testing JACK and PA latency, Fons Adriaensen, (Thu Sep 19, 9:42 am)
Re: [LAU] Testing JACK and PA latency, Patrick Shirkey, (Thu Sep 19, 10:04 am)
Re: [LAU] Testing JACK and PA latency, Fons Adriaensen, (Thu Sep 19, 10:46 am)
Re: [LAU] Testing JACK and PA latency, Patrick Shirkey, (Wed Sep 25, 1:32 pm)
Re: [LAU] Testing JACK and PA latency, Len Ovens, (Thu Sep 19, 2:01 pm)
Re: [LAU] Testing JACK and PA latency, Patrick Shirkey, (Thu Sep 19, 2:21 pm)
Re: [LAU] Testing JACK and PA latency, Len Ovens, (Thu Sep 19, 11:48 pm)
Re: [LAU] Testing JACK and PA latency, Patrick Shirkey, (Fri Sep 20, 12:57 am)
Re: [LAU] Testing JACK and PA latency, Patrick Shirkey, (Fri Sep 20, 8:59 am)
Re: [LAU] Testing JACK and PA latency, Fons Adriaensen, (Fri Sep 20, 10:31 am)
Re: [LAU] Testing JACK and PA latency, Patrick Shirkey, (Fri Sep 20, 10:41 am)
Re: [LAU] Testing JACK and PA latency, Fons Adriaensen, (Fri Sep 20, 3:13 pm)
Re: [LAU] Testing JACK and PA latency, Patrick Shirkey, (Fri Sep 20, 6:07 pm)
Re: [LAU] Testing JACK and PA latency, Fons Adriaensen, (Fri Sep 20, 7:08 pm)
Re: [LAU] Testing JACK and PA latency, Patrick Shirkey, (Sat Sep 21, 11:27 am)
Re: [LAU] Testing JACK and PA latency, Patrick Shirkey, (Thu Sep 19, 3:40 pm)
Re: [LAU] Testing JACK and PA latency, Fons Adriaensen, (Thu Sep 19, 12:31 pm)
Re: [LAU] Testing JACK and PA latency, Patrick Shirkey, (Thu Sep 19, 12:35 pm)
Re: [LAU] Testing JACK and PA latency, Patrick Shirkey, (Thu Sep 19, 10:26 am)
Re: [LAU] Testing JACK and PA latency, Hartmut Noack, (Thu Sep 19, 9:20 am)
Re: [LAU] Testing JACK and PA latency, Patrick Shirkey, (Thu Sep 19, 9:39 am)
Re: [LAU] Testing JACK and PA latency, Len Ovens, (Thu Sep 19, 1:49 pm)
Re: [LAU] Testing JACK and PA latency, Patrick Shirkey, (Thu Sep 19, 2:04 pm)