man alsa_delay (1): measure round-trip latency of a soundcard

SYNOPSIS

alsa_delay playdev captdev fsamp frsize nfrags

DESCRIPTION

This tool can be used to measure the round-trip latency of a soundcard. To do this, start the program and connect like this:

  alsa_delay -> playdev -> cable from soundcard output to input -> captdev -> alsa_delay

alsa_delay should be able to measure the round-trip latency with an accuracy of around 1/1000 of a sample. The assumption is, that the latency is more or less independent of frequency, and that the cable between soundcard output and input has virtually zero latency.

ARGUMENTS

playdev: ALSA playback device (e.g.: hw:0)
captdev: ALSA capture device (e.g.: hw:0)
fsamp: Sample rate (e.g.: 48000)
frsize: Period size (e.g.: 256)
nfrags: Number of fragments (e.g.: 2)

EXAMPLES

This will measure and display the round-trip latency of soundcard hw:0 using 48kHz samplerate, and 10 fragments each 2048 samples.

  alsa_delay hw:0 hw:0 48000 2048 10

NOTES

alsa_delay is a port of jack_delay (by the same author) to ALSA.

AUTHOR

zita-alsa-pcmi was written by Fons Adriaensen <[email protected]>.