NAME

       jack_delay - JACK sound card latency meter

DESCRIPTION

       jack_delay  can  be used to measure the round-trip latency of a soundcard.  To do this, start the program
       and connect like this: jack_delay -> playback_port -> cable from soundcard output  to  input  ->  capture
       port -> jack_delay

       jack_delay  generates  a  signal  consisting  of 13 sine waves, measures the phase difference between the
       input and output for each of these, and computes the delay from those phase  differences.  The  algorithm
       used  is  one  developed  originally  for  satellite  ranging -  that is measuring the distance between a
       satellite and a ground station.  With a good sound card jack_delay will measure  the  round-trip  latency
       with  an  accuracy  of  around  1/1000  of  a  sample.  The  assumption is that the delay is more or less
       independent of frequency. The actual value displayed is the one for a frequency of  1/16  of  the  sample
       rate.  The  phase  measurement  for this frequency of course only provides a result in the range of 0..16
       samples. The other frequencies are used to extend this interval to 4096 * 16 samples, more than a  second
       at 48 kHz.

OPTIONS

       -h     Display this text

       -O <playback port>
              connect output to named port. e.g. system:playback_1

       -I <capture port>
              connect input to named port. e.g. system:capture_1

       -E     show excess latency instead of full latency.

AUTHOR

       jack_delay was written by Fons Adriaensen <fons@linuxaudio.org>.

       This  manual  page was written by Jaromír Mikeš <mira.mikes@seznam.cz> for the Debian project (but may be
       used by others).

                                                   August 2017                                     JACK_DELAY(1)