JACK is a low-latency audio server, written primarily for the GNU/Linux
operating system. It can connect a number of different applications to
an audio device, as well as allowing them to share audio between
themselves. Its clients can run in their own processes (ie. as normal
applications), or can they can run within the JACK server (ie. as a
JACK is different from other audio server efforts in that it has been
designed from the ground up to be suitable for professional audio work.
This means that it focuses on two key areas: synchronous execution of
all clients, and low latency operation.
Source packages for Jack 0.90.0 are available
Buffers can resize during operation. This can be triggered by the user
or by the function jack_set_buffer_size(). See the documentation for
details. It is new code and still needs a shakedown. It can be enabled
with './configure --enable-resize'. If not compiled in,
jack_set_buffer_size() returns ENOSYS. Applications should be prepared
for it though.
Major rewrite of the thread model. This won't affect users.
Thanks to the rewrite, jack now has a "freewheeling" mode for faster
than realtime operation. It decouples the engine from the soundcard.
The alsa driver has 3 new options. --i, --inchannels sets the number of
channels to open for input. --o, --outchannels sets the number of
channels to open for output. -S, --shorts changes the order of in which
the sampleformats are tried. The driver will try to use 16bit samples
first and only tries 32bit if this fails. Useful if you digitaloutput
card supports 32bit samples but your interface doesn't.
Greatly increased support for other architectures.
--version also prints out the temporary directory.
Example clients expanded to be more helpful.
Many bug fixes.
Updated and improved documentation.
Portaudio driver works on linux.
jack_connect() returns EEXIST if a connection is already made.
Addition of jack_get_current_transport_frame ().
hw:0 is the default ALSA device instead of "default".
Jack's build system has better optimization.
--silent option for halting jackd's output.
Removal of --tmpdir and --asio options.
Will compile with alsa-lib-1.0.0pre1 (the latest).
Jack now has a mantis bugtracker at http://jackit.sf.net/mantis/
Please use that for bug reports.
James has written a tutorial for jack programmers available at
These are deprecated structures and functions that have been
deprecated. They will likely be removed in a future release.
The jack_transport_info_t struct has been deprecated. Please use
jack_engine_takeover_timebase() has been deprecated. Please use
jack_set_server_dir() has been deprecated.
jack_get_transport_info() has been deprecated. Please use
jack_set_transport_info() has been deprecated. Instead, define a