On Thu, September 19, 2013 8:04 pm, Patrick Shirkey wrote: > > On Thu, September 19, 2013 7:42 pm, Fons Adriaensen wrote: >> 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). >> > > Can I use jack_delay running on a second computer connected to the > external i/o of the first computer to get this value? > > >> 2. Measure >> >> jack_delay -> pa_source -> audacity -> pa_sink -> jack_delay. >> > > > Does this look reasonable? > > 1023.978 frames 21.333 ms total roundtrip latency > extra loopback latency: 1023 frames > use 511 for the backend arguments -I and -O > 1023.976 frames 21.333 ms total roundtrip latency > extra loopback latency: 1023 frames > use 511 for the backend arguments -I and -O > 1023.977 frames 21.333 ms total roundtrip latency > extra loopback latency: 1023 frames > use 511 for the backend arguments -I and -O > If I use ecasound instead of audacity: ecasound -f:32,2,48000 -b:32 -i alsa -o alsa 8095.992 frames 168.667 ms total roundtrip latency extra loopback latency: 8095 frames use 4047 for the backend arguments -I and -O 8095.992 frames 168.667 ms total roundtrip latency extra loopback latency: 8095 frames use 4047 for the backend arguments -I and -O 8095.992 frames 168.667 ms total roundtrip latency extra loopback latency: 8095 frames use 4047 for the backend arguments -I and -O 8095.994 frames 168.667 ms total roundtrip latency extra loopback latency: 8095 frames use 4047 for the backend arguments -I and -O ecasound -f:32,2,48000 -b:64 -i alsa -o alsa 9280.000 frames 193.333 ms total roundtrip latency extra loopback latency: 9280 frames use 4640 for the backend arguments -I and -O 9280.000 frames 193.333 ms total roundtrip latency extra loopback latency: 9280 frames use 4640 for the backend arguments -I and -O 9279.999 frames 193.333 ms total roundtrip latency extra loopback latency: 9279 frames use 4639 for the backend arguments -I and -O > > >> 3. If pa_source and pa_sink are a single Jack client (probably not), >> subtract one period from the result of (2). >> > > Can you explain that with the data above? > > >> 4. Add the two values. >> > > I would like to provide an app for this task. Do you think it would be > worthwhile to extend jack_iodelay for this purpose? > > -- Patrick Shirkey Boost Hardware Ltd _______________________________________________ Linux-audio-user mailing list Linux-audio-user@xxxxxxxxxxxxxxxxxxxx http://lists.linuxaudio.org/listinfo/linux-audio-user
