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author | sletz <sletz@0c269be4-1314-0410-8aa9-9f06e86f4224> | 2011-03-09 12:32:36 +0000 |
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committer | sletz <sletz@0c269be4-1314-0410-8aa9-9f06e86f4224> | 2011-03-09 12:32:36 +0000 |
commit | 21dfcfe6067d69e085f6a5f671187c5d1da4ee36 (patch) | |
tree | d327c362332e0db25e17aa489eb0027db3f34434 /man | |
parent | 246b75a99bcd7b223a73bdf5b58841709bb87dd5 (diff) | |
download | jack2-21dfcfe6067d69e085f6a5f671187c5d1da4ee36.tar.gz |
Rename jdelay to jack_iodelay as per Fons' request.
git-svn-id: http://subversion.jackaudio.org/jack/jack2/trunk/jackmp@4163 0c269be4-1314-0410-8aa9-9f06e86f4224
Diffstat (limited to 'man')
-rw-r--r-- | man/jack_iodelay.0 | 53 |
1 files changed, 53 insertions, 0 deletions
diff --git a/man/jack_iodelay.0 b/man/jack_iodelay.0 new file mode 100644 index 00000000..007e65a1 --- /dev/null +++ b/man/jack_iodelay.0 @@ -0,0 +1,53 @@ +.TH JACK_IODELAY "1" "!DATE!" "!VERSION!" +.SH NAME +jack_iodelay \- JACK toolkit client to measure roundtrip latency +.SH SYNOPSIS +.B jack_iodelay +.SH DESCRIPTION +.B jack_iodelay +will create one input and one output port, and then +measures the latency (signal delay) between them. For this to work, +the output port must be connected to its input port. The measurement +is accurate to a resolution of greater than 1 sample. +.PP +The expected use is to connect jack_iodelay's output port to a +hardware playback port, then use a physical loopback cable from the +corresponding hardware output connector to an input connector, and to +connect that corresponding hardware capture port to jack_iodelay's +input port. This creates a roundtrip that goes through any +analog-to-digital or digital-converters that are present in the audio +hardware. +.PP +Although the hardware loopback latency is the expected use, it is also +possible to use jack_iodelay to measure the latency along any fully +connected signal path, such as those involving other JACK clients. +.PP +Once jack_iodelay completes its measurement it will print the total +latency it has detected. This will include the JACK period length in +addition to any other latency in the signal path. It will continue to +print the value every 0.5 seconds or so so that if you wish you can +vary aspects of the signal path to see their effect on the measured +latency. +.PP +If no incoming signal is detected from the input port, jack_iodelay +will print +.PP +\fT Signal below threshold... .\fR +.PP +every second until this changes (e.g. until you establish the correct connections). +.PP +To use the value measured by jack_iodelay with the -I and -O arguments +of a JACK backend (also called Input Latency and Output Latency in the +setup dialog of qjackctl), you must subtract the JACK period size from +the result. Then, if you believe that the latency is equally +distributed between the input and output parts of your audio hardware +(extremely likely), divide the result by two and use that for input +and/or output latency value. Doing this measurement will enable JACK +clients that use the JACK latency API to accurately position/delay +audio to keep signals synchronized even when there are inherent delays +in the end-to-end signal pathways. +.SH AUTHOR +Originally written in C++ by Fons Adriensen, ported to C by Torben Hohn. + + + |