.TH zita-alsa-pcmi "1" "July 2013"
.SH NAME
alsa_delay \- measure round-trip latency of a soundcard
.SH SYNOPSIS
.B alsa_delay
.RI playdev
.RI captdev
.RI fsamp
.RI frsize
.RI nfrags
.SH 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:
.nf
  alsa_delay -> playdev -> cable from soundcard output to input -> captdev -> alsa_delay
.fi
.PP
.BR 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.
.SH ARGUMENTS
.TP
\fBplaydev\fR
ALSA playback device (e.g.: hw:0)
.TP
\fBcaptdev\fR
ALSA capture device (e.g.: hw:0)
.TP
\fBfsamp\fR
Sample rate (e.g.: 48000)
.TP
\fBfrsize\fR
Period size (e.g.: 256)
.TP
\fBnfrags\fR
Number of fragments (e.g.: 2)
.SH EXAMPLES
This will measure and display the round-trip latency of soundcard
.BR hw:0
using 48kHz samplerate, and 10 fragments each 2048 samples.
.nf
  alsa_delay hw:0 hw:0 48000 2048 10
.fi
.SH NOTES
.BR alsa_delay
is a port of
.BR jack_delay
(by the same author) to ALSA.
.SH "AUTHOR"
zita-alsa-pcmi was written by Fons Adriaensen <fons@linuxaudio.org>.
.PP
This manual page was written by IOhannes m zmoelnig <zmoelnig@iem.at>
for the Debian project (but may be used by others).