Editing JACK Audio Connection Kit

{{Short description|Professional sound server for Unix-like operating systems}}
{{Infobox software
| name = JACK Audio Connection Kit
| logo = LogoJack.png
| author = [[Paul Davis (programmer)|Paul Davis]], Stéphane Letz
| developer = JACK team
| released = {{start date|2002}}
| repo = {{URL|https://github.com/jackaudio/jack2}}
| operating_system = [[BSD]], [[Linux]], [[macOS]], [[Solaris (operating system)|Solaris]], [[Microsoft Windows|Windows]], [[iOS]]
| programming language = [[C (programming language)|C]],<ref>{{cite web |url=https://www.openhub.net/p/jack |title=JACK |work=Analysis Summary |publisher=[[Ohloh]] |access-date=2012-01-08}}</ref> [[C++]]
| genre = [[Sound server]]
| license = Server: [[GNU General Public License|GPL-2.0-or-later]]<br />Library: [[GNU Lesser General Public License|LGPL-2.1-or-later]]<ref name="license">{{cite web
 | url          = https://jackaudio.org/api/
 | title        = JACK Audio Connection Kit - License
 | access-date   = 2021-06-08
 | archive-url  = https://web.archive.org/web/20210503015727/https://jackaudio.org/api/
 | archive-date = 2021-05-03
 | url-status   = live}}</ref>
| website = {{official URL}}
| latest release version = {{multiple releases
  | branch1  = JACK1:
  | version1 = v0.126.0
  | date1    = {{Start date and age|2022|01|15}}

  | branch2  = JACK2:
  | version2 = v1.9.22
  | date2    = {{Start date and age|2023|02|03}}
}}
}}

'''JACK Audio Connection Kit''' (or '''JACK'''; a [[recursive acronym]]) is a professional [[sound server]] [[Application programming interface|API]] and pair of [[daemon (computing)|daemon]] implementations to provide real-time, [[low-latency]] connections for both audio and MIDI data between applications. JACK was developed by a community of open-source developers led by [[Paul Davis (programmer)|Paul Davis]] (who won an Open Source Award in 2004 for this work)<ref>{{cite web |url=http://www.techrepublic.com/article/open-source-awards-2004-paul-davis-for-jack/ |title=Open Source Awards 2004: Paul Davis for JACK |publisher=techrepublic.com.com |access-date=24 May 2016}}</ref> and has been a key piece of infrastructure and the [[de facto standard]] for professional audio software on Linux since its inception in 2002. The server is [[free software]], licensed under [[GNU General Public License|GPL-2.0-or-later]], while the library is licensed under [[GNU Lesser General Public License|LGPL-2.1-or-later]].<ref name="license" />

== 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.<ref>{{cite web|title=What's new in JACK2? - Linux Audio Conference 2009 paper by primary JACK2 author Stephane Letz|url=http://lad.linuxaudio.org/events/2009_cdm/Thursday/01_Letz/|archive-url=https://archive.today/20120709233707/http://lad.linuxaudio.org/events/2009_cdm/Thursday/01_Letz/|url-status=dead|archive-date=July 9, 2012|access-date=17 February 2010|publisher=linuxaudio.org}}</ref>

JACK can be used with [[ALSA (Linux)|ALSA]], [[PortAudio]], [[CoreAudio]], [[FFADO]] and [[Open Sound System|OSS]] as hardware [[Front and back ends|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]], [[macOS]], [[Solaris (operating system)|Solaris]], [[Microsoft Windows|Windows]], [[iOS]], [[FreeBSD]], [[OpenBSD]] and [[NetBSD]].

The JACK API is also implemented by [[PipeWire]] for [[Backward compatibility|backwards compatibility]] as a complete drop-in replacement provider for JACK clients, mapping JACK API calls to equivalent PipeWire calls.<ref>{{cite web |title=JACK - Wiki - PipeWire/pipewire |url=https://gitlab.freedesktop.org/pipewire/pipewire/-/wikis/JACK |website=PipeWire on GitLab |access-date=11 February 2021}}</ref> 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.<ref>{{cite web |title=FAQ - Wiki - PipeWire/pipewire |url=https://gitlab.freedesktop.org/pipewire/pipewire/-/wikis/FAQ#is-pipewire-another-jack-implementation |website=PipeWire on GitLab |access-date=11 February 2021}}</ref> The use of PipeWire as the default implementation of JACK is the default on [[Fedora (operating system)|Fedora]] 34 and newer.<ref>{{cite web |last1=Larabel |first1=Michael |title=Fedora 34 Gets Sign-Off For Trying To Default To PipeWire For Audio Needs |url=https://www.phoronix.com/scan.php?page=news_item&px=Fedora-34-PipeWire-Attempt |website=Phoronix |publisher=Phoronix Media |access-date=11 February 2021}}</ref>

== Low-latency scheduling ==
[[File:Linux kernel and daemons with exclusive access.svg|thumb|Like [[PulseAudio]], JACK daemon is an "audio daemon", i.e. it does mixing of audio from applications via software. For this it assumes to have exclusive access to the kernel's audio sub-system.]]

The [[Scheduling (computing)|scheduling]] requirements of JACK to achieve sufficiently low latencies were one of the driving forces behind the [[real-time operating system|real-time]] optimization effort for the [[Linux kernel]] 2.6 series,<ref>{{cite web |url=https://lkml.org/lkml/2004/7/9/138 |title=Original announcement of a voluntary pre-emption patch for the Linux 2.6 kernel series by Ingo Molnar, 2004 |publisher=lkml.org |access-date=17 February 2010}}</ref><ref>{{cite web |url=https://lwn.net/images/conf/rtlws11/papers/proc/p02.pdf |title=Finding Origins of Latencies Using Ftrace, paper by Steven Rostedt from the Real-time Workshop 2009 |access-date=17 February 2010}}</ref> whose initial latency performance had been disappointing compared to the older 2.4 series.<ref>{{cite web |url=http://lac.zkm.de/2006/papers/lac2006_lee_revell.pdf |title=Real-time audio vs. 2.6, Linux Audio Conference 2006 paper by Lee Revell |access-date=17 February 2010 |archive-date=10 November 2020 |archive-url=https://web.archive.org/web/20201110045534/http://lac.zkm.de/2006/papers/lac2006_lee_revell.pdf |url-status=dead }}</ref> 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 [[PREEMPT_RT|CONFIG_PREEMPT_RT patch]].<ref>{{cite web |url=http://rt.wiki.kernel.org/ |title=Real-Time Linux Wiki |publisher=[[Kernel.org]] (The Linux Kernel Archives) |access-date=8 June 2010}}</ref>

== Applications with JACK support ==
{{Category see also|Audio software with JACK support}}

== See also ==
{{Portal|Free and open-source software}}
* [[LADSPA]] & [[LV2]] – APIs for plugins
* [[PulseAudio]] – sound server for desktop use
* [[List of Linux audio software]]
* [[Comparison of free software for audio]]
* [[Audio_Stream_Input/Output#Free_alternatives|ASIO free alternatives]]

== References ==
{{reflist|30em}}

== External links ==
* {{Official website}}


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