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JACK_CAPTURE(1) General Commands Manual JACK_CAPTURE(1)


jack_capture - A program for recording anything from jack


jack_capture [options]
bar [options]


This manual page documents briefly the jack_capture command. This manual page was written for the Debian distribution because the original program does not have a manual page.

jack_capture is a cli program for recording any audio signal from jack to audio audio formats supported by libsndfile library (wav, aiff, ogg, flac, wavex, au, etc.)

For more info about libsndfile see


These programs follow the usual GNU command line syntax, with long options starting with two dashes (`-'). A summary of options is included below.

is by default FLOAT. It can be set to either 8, 16, 24 or 32. (for relevant formats)
is by default 2.
is by default set to the two first physical outputs. The "port" argument can be specified more than once.
Recording is stopped after "s" seconds.
"n" is the number of zeros to in the autogenerated filename. (-z 2 -> jack_capture_001.wav, and so on.) (default is 1)
Selects fileformat provided by libsndfile. See (Default is wav for 1 or 2 channels, and wavex for more than 2.)
Prints all sound formats provided to sndfile to screen and then exits.
Prints out version.
Suppress some common messages printed to the terminal.
Prints some extra information to the terminal.
Writes to an mp3 file using liblame (LAME). (the --format option has no effect using this option)
Selects mp3 quality provided by liblame. n=0 is best, n=9 is worst. Default n is 2. (0 uses the most amount of CPU, 9 uses the least)
Selects mp3 bitrate (in kbit/s). Default is set by liblame. (currently 128)
Writes 16 bit little endian to stdout. (the --format option, the --mp3 option, and some others have no effect using this option)
Disable console meter
Disable buffer usage.
Disable console updates. Same as "-dm -hbu".
Use linear scale for the console meter (default is dB scale)
Specify reference level for dB meter. (default=0)
Start up meterbridge to monitor recorded sound.
Specify type. vu (default), ppm, dpm, jf or sco.
Specify reference level for meterbidge.
Start program, but do not start recording until jack transport has started rolling. When jack transport stops, the recording is stopped, and the program ends.
Similar to --jack-transport, but do not end program when jack transport stops. Instead, record to a new file when jack_transport start rolling again. (not implemented yet)
Initial/minimum buffer size in seconds. Default is 8 seconds for mp3 files, and 4 seconds for all other formats.
Maximum buffer size in seconds. jack_capture will allocate. Default is 40. (Buffer is automatically increased during
Specify filename. (It's usually easier to set last argument instead)


jack_capture [--bitdepth n] [--channels n] [--port port] [filename]
jack_capture [-b n] [-c n] [-p port] [filename]
To record a stereo file of what you hear.
To record a stereo file of what you hear in the flac format.
jack_capture -f ogg
To record a stereo file of what you hear in the ogg format.
jack_capture -mp3
To record a stereo file of what you hear in the mp3 format.
jack_capture --channels 2 --port system:playback*
To record a stereo file of what you hear in the wav format.
jack_capture --port jamin:out* sound_from_jamin.wav
To record the output from jamin.
jack_capture --port jamin:in* sound_to_jamin.wav
To record all sound coming in to jamin.
jack_capture --port jamin* sound_to_and_from_jamin.wav
To record all sound coming in and out of jamin.
jack_capture -c 2 -p system:capture*
To record a stereo file from the soundcard.




jack_capture was written by Kjetil Matheussen

This manual page was written by Jaromír Mikeš <>, for the Debian project (but may be used by others).

July 28, 2010