[LAU] Testing JACK and PA latency

Fons Adriaensen fons at linuxaudio.org
Thu Sep 19 09:42:10 UTC 2013

On Thu, Sep 19, 2013 at 06:46:11PM +1000, Patrick Shirkey wrote:
> 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)

Easy using jack_delay.

1. Measure the round-trip latency of your sound card (with an
external analog loop).

2. Measure

  jack_delay -> pa_source -> audacity -> pa_sink -> jack_delay.

3. If pa_source and pa_sink are a single Jack client (probably not),
   subtract one period from the result of (2).

4. Add the two values.  


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