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

there isn't any way to separately compute the "outbound" and "inbound"
latency. in fact, jack_iodelay's message about the value to use for -I and
-O is based on the not-entirely-defensible but somewhat reasonable
assumption that the outbound and inbound latencies are symmetric.

put differently, i don't think there is any way to do what you want.
someone may prove me wrong.


On Wed, Sep 18, 2013 at 6:55 AM, Patrick Shirkey <[hidden]
> wrote:

>
> 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
> 
> Jack-Devel mailing list
> [hidden]
> http://lists.jackaudio.org/listinfo.cgi/jack-devel-jackaudio.org
>

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