Re: [Jack-Devel] Testing JACK and PA latency

On Wed, September 18, 2013 4:49 pm, Patrick Shirkey wrote:
> Hi,
>
> Can anyone recommend a rigorous procedure for verifying round trip latency
> between i/o using a combination of both JACK and PA?
>
>

I have the following setup:

jack running in duplex mode (1024/48000/2)
pa connected to jack with sink/source plugins
skype* running via pa
jack_iodelay

I have the following connections

     jack_delay (out) -> pa jack source (1)
     system_in (1) -> jack_delay (in)
     system_in (1) -> pa jack source (1)
     pa jack sink -> system_out (1)

I can hear the output signal from jack_delay in the skype call test service.
I can hear the mic input in skype call test service
I can hear skype output in my speakers via jack system output

I see the following info in jack_delay console messages:

 22120.239 frames    460.838 ms total roundtrip latency
	extra loopback latency: 21096 frames
	use 10548 for the backend arguments -I and -O ??


However I don't think this setup is calculating latency details that I am
looking for.

I would like to retrieve the following info:

1: latency from jack system in -> pa_source -> skype in -> skype network
output (before the data is transmitted to the external receiver)

2: latency from skype network input (immediately data that is received
from external provider) -> pa_sink -> jack_system out


* skype is used for testing i/o via PA. Any other duplex app could also be
used.





--
Patrick Shirkey
Boost Hardware Ltd

1379501733.5374_0.ltw:2, <52796.86.127.135.98.1379501724.squirrel at boosthardware dot com>