2 * This is the main page of the JACK reference manual, built using
7 @mainpage JACK Audio Connection Kit
9 @section intro Introduction
11 JACK is a low-latency audio server, written for any operating system
12 that is reasonably POSIX compliant. It currently exists for Linux, OS
13 X, Solaris, FreeBSD and Windows. It can connect several client
14 applications to an audio device, and allow them to share audio with
15 each other. Clients can run as separate processes like normal
16 applications, or within the JACK server as "plugins".
18 JACK was designed from the ground up for professional audio work, and
19 its design focuses on two key areas: synchronous execution of all
20 clients, and low latency operation.
22 @see <http://jackaudio.org>
24 @section jack_overview JACK Overview
26 Traditionally it has been hard if not impossible to write audio
27 applications that can share data with each other. In addition,
28 configuring and managing audio interface hardware has often been one
29 of the most complex aspect of writing audio software.
31 JACK changes all this by providing an API that does several things:
33 1. provides a high level abstraction for programmers that
34 removes the audio interface hardware from the picture and
35 allows them to concentrate on the core functionality of
38 2. allows applications to send and receive audio data to/from
39 each other as well as the audio interface. There is no
40 difference in how an application sends or receives
41 data regardless of whether it comes from/goes to another application
42 or an audio interface.
44 For programmers with experience of several other audio APIs such as
45 PortAudio, Apple's CoreAudio, Steinberg's VST and ASIO as well as many
46 others, JACK presents a familiar model: your program provides a
47 "callback" function that will be executed at the right time. Your
48 callback can send and receive data as well as do other signal
49 processing tasks. You are not responsible for managing audio
50 interfaces or threading, and there is no "format negotiation": all
51 audio data within JACK is represented as 32 bit floating point values.
53 For those with experiences rooted in the Unix world, JACK presents a
54 somewhat unfamiliar API. Most Unix APIs are based on the read/write
55 model spawned by the "everything is a file" abstraction that Unix is
56 rightly famous for. The problem with this design is that it fails to
57 take the realtime nature of audio interfaces into account, or more
58 precisely, it fails to force application developers to pay sufficient
59 attention to this aspect of their task. In addition, it becomes rather
60 difficult to facilitate inter-application audio routing when different
61 programs are not all running synchronously.
63 Using JACK within your program is very simple, and typically consists
66 - calling @ref jack_client_open() to connect to the JACK server.
67 - registering "ports" to enable data to be moved to and from
69 - registering a "process callback" which will be called at the
70 right time by the JACK server.
71 - telling JACK that your application is ready to start processing
74 There is a lot more that you can do with JACK's interfaces, but for
75 many applications, this is all that is needed. The @ref
76 simple_client.c example demonstrates a complete (simple!) JACK
77 application that just copies the signal arriving at its input port to
78 its output port. Similarly, @ref inprocess.c shows how to write an
79 internal client "plugin" that runs within the JACK server process.
81 @section reference Reference
83 The JACK programming interfaces are described in several header files.
84 We present them here broken into useful categories to make the API a
87 - @ref ClientFunctions
88 - @ref ClientCallbacks
94 - @ref TransportControl
99 The full API is described in:
101 - @ref jack.h "<jack/jack.h>" is the main JACK interface.
102 - @ref statistics.h "<jack/statistics.h>" provides interfaces for
103 monitoring the performance of a running JACK server.
104 - @ref intclient.h "<jack/intclient.h>" allows loading and unloading
105 JACK internal clients.
106 - @ref ringbuffer.h "<jack/ringbuffer.h>" defines a simple API for
107 using lock-free ringbuffers. These are a good way to pass data
108 between threads, when streaming realtime data to slower media, like
109 audio file playback or recording.
110 - @ref transport.h "<jack/transport.h>" defines a simple transport
111 control mechanism for starting, stopping and repositioning clients.
112 This is described in the @ref transport-design document.
113 - @ref types.h "<jack/types.h>" defines the main JACK data types.
114 - @ref thread.h "<jack/thread.h>" functions standardize thread
115 creation for JACK and its clients.
116 - @ref midiport.h "<jack/midiport.h>" functions to handle reading
117 and writing of MIDI data to a port
119 In addition, the tools directory provides numerous examples
120 of simple JACK clients that nevertheless use the API to do something
124 - a recording client that can capture any number of channels
125 from any JACK sources and store them as an audio file.
126 - command line clients to control the transport mechanism,
127 change the buffer size and more.
128 - commands to load and unload JACK internal clients.
129 - tools for checking the status of a running JACK system.
133 @section porting Porting
135 JACK is designed to be portable to any system supporting the relevant
136 POSIX and ANSI C standards. It currently runs under GNU/Linux, Mac OS
137 X and Berkeley Unix on several different processor architectures. If
138 you want to port JACK to another platform, please read the @ref
139 porting-guide document.
141 @section license License
143 Copyright (C) 2001-2008 by Paul Davis and others.
145 JACK is free software; you can redistribute it and/or modify it under
146 the terms of the GNU GPL and LGPL licenses as published by the Free
147 Software Foundation, <http://www.gnu.org>. The JACK server uses the
148 GPL, as noted in the source file headers. However, the JACK library
149 is licensed under the LGPL, allowing proprietary programs to link with
150 it and use JACK services. You should have received a copy of these
151 Licenses along with the program; if not, write to the Free Software
152 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
155 This program is distributed in the hope that it will be useful, but
156 WITHOUT ANY WARRANTY; without even the implied warranty of
157 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
158 General Public License for more details.