JACK Audio Connection Kit (or JACK; a

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) is a professional sound server

API An application programming interface (API) is a connection between computers or between computer programs. It is a type of software interface, offering a service to other pieces of software. A document or standard that describes how to build ...

and pair of

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implementations to provide real-time,

low-latency Latency, from a general point of view, is a time delay between the cause and the effect of some physical change in the system being observed. Lag, as it is known in gaming circles, refers to the latency between the input to a simulation and t ...

connections for both audio and MIDI data between applications. JACK was developed by a community of open-source developers led by Paul Davis (who won an Open Source Award in 2004 for this work) and has been a key piece of infrastructure and the

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for professional audio software on Linux since its inception in 2002. The server is

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, licensed under GPL-2.0-or-later, while the library is licensed under LGPL-2.1-or-later.

Implementations

The JACK API is standardized by consensus, and two compatible implementations exist: jack1, which is implemented in plain C and has been in maintenance mode for a while, and jack2 (originally jackdmp), a re-implementation in C++ originally led by Stéphane Letz, which introduced multi-processor scalability and support for operating systems other than Linux. JACK can be used with ALSA, PortAudio, CoreAudio, FFADO and

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as hardware back-ends. Additionally, a dummy driver (useful if no sound output is desired, e.g. for offline rendering) and an Audio-over-UDP driver exist. One or both implementations can run on

Linux Linux ( ) is a family of open source Unix-like operating systems based on the Linux kernel, an kernel (operating system), operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically package manager, pac ...

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and

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. The JACK API is also implemented by PipeWire for

backwards compatibility In telecommunications and computing, backward compatibility (or backwards compatibility) is a property of an operating system, software, real-world product, or technology that allows for interoperability with an older legacy system, or with Input ...

as a complete drop-in replacement provider for JACK clients, mapping JACK API calls to equivalent PipeWire calls. If used as a replacement for ALSA and PulseAudio as well, it can unify the different sound servers and APIs that might be typically found on a machine, and allow better integration between different software. PipeWire also claims to add a number of features and fix a number of limitations compared to JACK. The use of PipeWire as the default implementation of JACK is the default on

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34 and newer.

Low-latency scheduling

Linux kernel and daemons with exclusive access

The

scheduling A schedule (, ) or a timetable, as a basic time-management tool, consists of a list of times at which possible tasks, events, or actions are intended to take place, or of a sequence of events in the chronological order in which such things ...

requirements of JACK to achieve sufficiently low latencies were one of the driving forces behind the

real-time Real-time, realtime, or real time may refer to: Computing * Real-time computing, hardware and software systems subject to a specified time constraint * Real-time clock, a computer clock that keeps track of the current time * Real-time Control Syst ...

optimization effort for the

Linux kernel The Linux kernel is a Free and open-source software, free and open source Unix-like kernel (operating system), kernel that is used in many computer systems worldwide. The kernel was created by Linus Torvalds in 1991 and was soon adopted as the k ...

2.6 series, whose initial latency performance had been disappointing compared to the older 2.4 series. Real-time tuning work culminated in numerous scheduling improvements to the mainline kernel and the creation of an -rt branch for more intrusive optimizations in the release 2.6.24, and later the CONFIG_PREEMPT_RT patch.

Applications with JACK support

References

External links

* {{DEFAULTSORT:Jack Audio Connection Kit Application programming interfaces Audio libraries Audio software for Linux Free audio software Linux APIs Music software plugin architectures

Implementations

Low-latency scheduling

Applications with JACK support

See also

References

External links