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)