jack2/man/jackd.0

.TH "JACKD" "1" "!DATE!" "!VERSION!" ""
.SH "NAME"
\fBjackd\fR \- JACK Audio Connection Kit sound server


.SH "SYNOPSIS"
\fBjackd\fR [\fIoptions\fR] \fB\-d\fI backend \fR 
[\fIbackend\-parameters\fR]
.br
\fBjackd \-\-help\fR


.SH "DESCRIPTION"
\fBjackd\fR is the JACK audio server daemon that allows JACK client 
programs to process and route audio and MIDI data in a synchronous, 
sample-accurate and low\-latency manner. Originally written for the
GNU/Linux operating system, it also runs on various Unix platforms, 
Mac OS X and MS Windows.
JACK can connect a number of different client applications
to an audio device and also to each other. Most clients are external,
running in their own processes as normal applications. JACK also
supports internal clients, which run within the \fBjackd\fR process
using a loadable "plugin" interface.

JACK differs from other audio servers in being designed from the
ground up for professional audio work. It focuses on two key areas:
synchronous execution of all clients and low latency operation.

The name JACK makes a reference to the classical way of patching audio 
connections with physical audio jack cables.
JACK is also a recursive acronym, that is an abbreviation which is part 
of itself. \fIJ\fRACK \fIA\fRudio \fIC\fRonnection \fIK\fRit.

For the latest JACK information please consult the web site: 
<\fBhttp://www.jackaudio.org/\fR>.


.SH "OPTIONS"

.TP
\fB\-d, \-\-driver \fIbackend\fR [\fIbackend\-parameters\fR ]
.br
Select the audio interface backend. The current list of supported
backends is: \fBalsa\fR, \fBcoreaudio\fR, \fBdummy\fR, 
\fBfirewire\fR, \fBoss\fR \fBsun\fR and \fBportaudio\fR. They are 
not all available on all platforms. All \fIbackend\-parameters\fR are optional.

.TP
\fB\-h, \-\-help\fR
.br
Print a brief usage message describing the main \fBjackd\fR options.
These do not include \fIbackend\-parameters\fR, which are listed using
the \fB\-\-help\fR option for each specific backend. Examples below
show how to list them.

.TP
\fB\-a, \-\-autoconnect\fR \fImodechar\fR
Select how to handle self connect requests. They can be ignore or fail, 
on all port or just external ones. Use the \fB\-\-help\fR option to know 
your system specific options. The default is to not restrict self connect 
requests.
.TP
\fB\-m, \-\-no\-mlock\fR
Do not attempt to lock memory, even if \fB\-\-realtime\fR.

.TP
\fB\-n, \-\-name\fR \fIserver\-name\fR
Name this \fBjackd\fR instance \fIserver\-name\fR. If unspecified,
this name comes from the \fB$JACK_DEFAULT_SERVER\fR environment
variable. 
(default: "default")

.TP
\fB\-p, \-\-port\-max \fI n\fR
Set the maximum number of ports the JACK server can manage. 
(default: 256)

.TP
\fB\-\-replace-registry\fR 
.br
Remove the shared memory registry used by all JACK server instances
before startup. This should rarely be used, and is intended only
for occasions when the structure of this registry changes in ways
that are incompatible across JACK versions (which is rare).

.TP
\fB\-R, \-\-realtime\fR 
.br
Use realtime scheduling. This is needed for reliable low\-latency
performance. On many systems, it requires \fBjackd\fR to run with
special scheduler and memory allocation privileges, which may be
obtained in several ways. 
(default: true) 

.TP
\fB\-r, \-\-no-realtime\fR
.br
Do not use realtime scheduling. 

.TP
\fB\-P, \-\-realtime\-priority \fIint\fR
When running \fB\-\-realtime\fR, set the scheduler priority to
\fIint\fR.

.TP
\fB\-\-silent\fR
Silence any output during operation.


.TP
\fB\-T, \-\-temporary\fR
Exit once all clients have closed their connections.

.TP
\fB\-t, \-\-timeout \fIint\fR
.br
Set client timeout limit in milliseconds.
In realtime mode the client timeout must be smaller than the watchdog timeout (5000 msec). 
(default: 500)

.TP
\fB\-Z, \-\-nozombies\fR
.br
Prevent JACK from ever kicking out clients because they were too slow.
This cancels the effect any specified timeout value, but JACK and its clients are
still subject to the supervision of the watchdog thread or its equivalent.

.TP
\fB\-C, \-\-internal-session-file \fIinternal-session-file\fR
.br
Load internal clients and connections from \fIinternal-session-file\fR.
Each line of this configuration file starts with a command.
The following commands are available:
.br
\fBl(oad)\fR \fIclient-name lib-name client-args\fR
.br
With this command an internal JACK client will be instantiated.
\fIclient-name\fR and \fIlib-name\fR cannot contain spaces.
The rest of the line will be interpreted as \fIclient-args\fR and 
sent to the client library.
.br
\fBc(on)\fR \fIsource-port destination-port\fR
.br
With this command a source port will be connected to a destination port.
\fIsource-port\fR and \fIdestination-port\fR cannot contain spaces.
.br
Comments are allowed, they start with \fB#\fR.
.br
An example configuration could look like the following:
.br
 l inprocess1 inprocess
 l amp1 jalv http://lv2plug.in/plugins/eg-amp
.br
 c amp:out system:playback_1

.TP
\fB\-u, \-\-unlock\fR
.br
Unlock libraries GTK+, QT, FLTK, Wine.

.TP
\fB\-v, \-\-verbose\fR
Give verbose output.

.TP
\fB\-c, \-\-clocksource\fR (\fI h(pet) \fR | \fI s(ystem) \fR)
Select a specific wall clock (HPET timer, System timer).

.TP
\fB\-V, \-\-version\fR
Print the current JACK version number and exit.


.SS ALSA BACKEND OPTIONS

.TP
\fB\-C, \-\-capture\fR [ \fIname\fR ]
Provide only capture ports, unless combined with \-D or \-P. Optionally set 
capture device name.

.TP
\fB\-d, \-\-device \fIname\fR
.br
The ALSA pcm device \fIname\fR to use. If none is specified, JACK will
use "hw:0", the first hardware card defined in \fB/etc/modules.conf\fR.

.TP
\fB\-z, \-\-dither [rectangular,triangular,shaped,none]
Set dithering mode. If \fBnone\fR or unspecified, dithering is off.
Only the first letter of the mode name is required.

.TP
\fB\-D, \-\-duplex\fR
Provide both capture and playback ports. Defaults to on unless only one 
of \-P or \-C is specified. 
(default: true)

.TP
\fB\-h, \-\-help\fR Print a brief usage message describing only the
\fBalsa\fR backend parameters.

.TP
\fB\-M, \-\-hwmeter\fR
.br
Enable hardware metering for devices that support it. Otherwise, use
software metering.

.TP
\fB\-H, \-\-hwmon\fR
.br
Enable hardware monitoring of capture ports. This is a method for
obtaining "zero latency" monitoring of audio input. It requires
support in hardware and from the underlying ALSA device driver.

When enabled, requests to monitor capture ports will be satisfied by
creating a direct signal path between audio interface input and output
connectors, with no processing by the host computer at all. This
offers the lowest possible latency for the monitored signal.

Presently (March 2003), only the RME Hammerfall series and cards based
on the ICE1712 chipset (M\-Audio Delta series, Terratec, and others)
support \fB\-\-hwmon\fR. In the future, some consumer cards may also
be supported by modifying their mixer settings.

Without \fB\-\-hwmon\fR, port monitoring requires JACK to read audio
into system memory, then copy it back out to the hardware again,
imposing the basic JACK system latency determined by the
\fB\-\-period\fR and \fB\-\-nperiods\fR parameters.

.TP
\fB\-i, \-\-inchannels \fIint\fR
.br
Number of capture channels. 
(default: maximum supported by hardware)

.TP
\fB\-I, \-\-input\-latency\fR
Extra input latency (frames). 
(default: 0)

.TP
\fB\-n, \-\-nperiods \fIint\fR
.br
Number of periods of playback latency. In seconds, this
corresponds to \fB\-\-nperiods\fR times \fB\-\-period\fR divided by
\fB\-\-rate\fR. The default is 2, the minimum allowed. For most
devices, there is no need for any other value with the
\fB\-\-realtime\fR option. Without realtime privileges or with boards
providing unreliable interrupts (like ymfpci), a larger value may
yield fewer xruns. This can also help if the system is not tuned for
reliable realtime scheduling.

For most ALSA devices, the hardware buffer has exactly
\fB\-\-period\fR times \fB\-\-nperiods\fR frames. Some devices demand
a larger buffer. If so, JACK will use the smallest possible buffer
containing at least \fB\-\-nperiods\fR, but the playback latency does
not increase.

For USB audio devices it is recommended to use \fB\-n 3\fR. Firewire
devices supported by FFADO (formerly FreeBoB) are configured with
\fB\-n 3\fR by default.

.TP
\fB\-o, \-\-outchannels \fIint\fR
.br
Number of playback channels. 
(default: maximum supported by hardware)

.TP
\fB\-O, \-\-output\-latency\fR
Extra output latency (frames). 
(default: 0)

.TP
\fB\-P, \-\-playback\fR [ \fIname\fR ]
Provide only playback ports, unless combined with \-D or \-C. Optionally set 
playback device name.

.TP
\fB\-p, \-\-period \fIint\fR
.br
Number of frames between JACK \fBprocess()\fR calls. This
value must be a power of 2. If you need low 
latency, set \fB\-p\fR as low as you can go without seeing xruns. A larger 
period size yields higher latency, but makes xruns less likely. The JACK 
capture latency in seconds is \fB\-\-period\fR divided by \fB\-\-rate\fR.
(default: 1024)

.TP
\fB\-r, \-\-rate \fIint\fR
Sample rate. 
(default: 48000)

.TP
\fB\-S, \-\-shorts
.br
Try to configure card for 16\-bit samples first, only trying 32\-bits if
unsuccessful. 
(default: 32\-bit samples)

.TP
\fB\-s, \-\-softmode\fR 
.br
Ignore xruns reported by the ALSA driver. This makes JACK less likely
to disconnect unresponsive ports when running without \fB\-\-realtime\fR.

.TP
\fB\-X, \-\-midi \fR[\fIseq\fR|\fIraw\fR]
.br
Which ALSA MIDI system to provide access to. Using \fBraw\fR
will provide a set of JACK MIDI ports that correspond to each raw ALSA
device on the machine. Using \fBseq\fR will provide a set of JACK MIDI
ports that correspond to each ALSA "sequencer" client (which includes
each hardware MIDI port on the machine). \fBraw\fR provides slightly
better performance but does not permit JACK MIDI communication with
software written to use the ALSA "sequencer" API.


.SS COREAUDIO BACKEND PARAMETERS

.TP
\fB\-c, \-\-channels\fR
Maximum number of channels. 
(default: 2)

.TP
\fB\-i, \-\-inchannels\fR
Maximum number of input channels.
(default: 2)

.TP
\fB\-o, \-\-outchannels\fR
Maximum number of output channels.
(default: 2)

.TP
\fB\-C, \-\-capture\fR
Whether or not to capture.
(default: true)

.TP
\fB\-P, \-\-playback\fR
Whether or not to playback.
(default: true)

.TP
\fB\-D, \-\-monitor\fR
Provide monitor ports for the output.
(default: false)

.TP
\fB\-D, \-\-duplex\fR
Capture and playback.
(default: true)

.TP
\fB\-r, \-\-rate\fR
Sample rate.
(default: 44100)

.TP
\fB\-p, \-\-period\fR
Frames per period, must be a power of 2. 
(default: 128)

.TP
\fB\-d, \-\-device\fR
CoreAudio device name. 
(default: none)

.TP
\fB\-I, \-\-input\-latency\fR
Extra input latency (frames). 
(default: 0)

.TP
\fB\-O, \-\-output\-latency\fR
Extra output latency (frames). 
(default: 0)

.TP
\fB\-l, \-\-list\-devices \fR
Display available CoreAudio devices. 
(default: false)

.TP
\fB\-H, \-\-hog \fR
Take exclusive access of the audio device. 
(default: false)

.TP
\fB\-L, \-\-async\-latency \fR
Extra output latency in asynchronous mode (percent). 
(default: 100)

.TP
\fB\-G, \-\-grain \fR
Computation grain in RT thread (percent). 
(default: 100)

.TP
\fB\-s, \-\-clock\-drift \fR
Whether or not to compensate clock drift in dynamically created aggregate device. 
(default: false)


.SS DUMMY BACKEND PARAMETERS

.TP
\fB\-C, \-\-capture \fIint\fR
Number of capture ports. 
(default: 2)

.TP
\fB\-P, \-\-playback \fIint\fR
Number of playback ports. 
(default: 2)

.TP
\fB\-r, \-\-rate \fIint\fR
Sample rate. 
(default: 48000)

.TP
\fB\-p, \-\-period \fIint\fR
Number of frames between JACK \fBprocess()\fR calls. This
value must be a power of 2. If you need low 
latency, set \fB\-p\fR as low as you can go without seeing xruns. A larger 
period size yields higher latency, but makes xruns less likely. The JACK 
capture latency in seconds is \fB\-\-period\fR divided by \fB\-\-rate\fR.
(default: 1024)

.TP
\fB\-w, \-\-wait \fIint\fR 
Number of usecs to wait between engine processes. 
(default: 21333)


.SS NETONE BACKEND PARAMETERS

.TP
\fB\-i, \-\-audio\-ins \fIint\fR
Number of capture channels. 
(default: 2)

.TP
\fB\-o, \-\-audio\-outs \fIint\fR
Number of playback channels. 
(default: 2)

.TP
\fB\-I, \-\-midi\-ins \fIint\fR
Number of midi capture channels. 
(default: 1)

.TP 
\fB\-O, \-\-midi\-outs \fIint\fR
Number of midi playback channels. 
(default: 1)

.TP
\fB\-r, \-\-rate \fIint\fR
Sample rate. 
(default: 48000)

.TP 
\fB\-p, \-\-period \fIint\fR
Frames per period. 
(default: 1024)

.TP 
\fB\-n, \-\-num\-periods \fIint\fR
Network latency setting in no. of periods. 
(default: 5)

.TP 
\fB\-l, \-\-listen\-port \fIint\fR
The socket port we are listening on for sync packets. 
(default: 3000)

.TP 
\fB\-f, \-\-factor \fIint\fR
Factor for sample rate reduction. 
(default: 1)

.TP 
\fB\-u, \-\-upstream\-factor \fIint\fR
Factor for sample rate reduction on the upstream. 
(default: 0)

.TP 
\fB\-c, \-\-celt \fIint\fR
Sets celt encoding and number of kbits per channel. 
(default: 0)

.TP 
\fB\-b, \-\-bit\-depth \fIint\fR
Sample bit\-depth (0 for float, 8 for 8bit and 16 for 16bit). 
(default: 0)

.TP 
\fB\-t, \-\-transport\-sync \fIint\fR
Whether or not to slave the transport to the master transport. 
(default: true)

.TP 
\fB\-a, \-\-autoconf \fIint\fR
Whether or not to use Autoconfig, or just start. 
(default: true)

.TP 
\fB\-R, \-\-redundancy \fIint\fR
Send packets N times. 
(default: 1)

.TP 
\fB\-e, \-\-native\-endian \fIint\fR
Don't convert samples to network byte order. 
(default: false)
.TP 
\fB\-J, \-\-jitterval \fIint\fR
Attempted jitterbuffer microseconds on master. 
(default: 0)

.TP 
\fB\-D, \-\-always\-deadline \fIint\fR
Always use deadline. 
(default: false)


.SS OSS BACKEND PARAMETERS

.TP
\fB\-r, \-\-rate \fIint\fR
Sample rate. 
(default: 48000)

.TP
\fB\-p, \-\-period \fIint\fR
Number of frames between JACK \fBprocess()\fR calls. This
value must be a power of 2. If you need low 
latency, set \fB\-p\fR as low as you can go without seeing xruns. A larger 
period size yields higher latency, but makes xruns less likely. The JACK 
capture latency in seconds is \fB\-\-period\fR divided by \fB\-\-rate\fR. 
(default: 1024)

.TP
\fB\-n, \-\-nperiods \fIint\fR
Number of periods in the hardware buffer. 
The period size (\fB\-p\fR) times \fB\-\-nperiods\fR times four is
the JACK buffer size in bytes. The JACK output latency in seconds is
\fB\-\-nperiods\fR times \fB\-\-period\fR divided by \fB\-\-rate\fR. 
(default: 2)

.TP
\fB\-w, \-\-wordlength \fIint\fR
Sample size in bits. 
(default: 16)

.TP
\fB\-i, \-\-inchannels \fIint\fR
Number of capture channels.
(default: 2)

.TP
\fB\-o, \-\-outchannels \fIint\fR
Number of playback channels. 
(default: 2)

.TP
\fB\-C, \-\-capture \fIdevice_file\fR
Input device for capture. 
(default: /dev/dsp)

.TP
\fB\-P, \-\-playback \fIdevice_file\fR
Output device for playback. 
(default: /dev/dsp)

.TP
\fB\-b, \-\-ignorehwbuf \fIboolean\fR
Whether or not to ignore hardware period size. 
(default: false)

.TP
\fB\-e, \-\-excl \fIboolean\fR
Request exclusive and direct access to the sound device.
This avoids mixing and automatic audio conversion in the
OSS driver, and the extra latency that comes with that.
(default: false)

.TP
\fB\-I, \-\-input\-latency\fR
Extra input latency (frames). 
(default: 0)

.TP
\fB\-O, \-\-output\-latency\fR
Extra output latency (frames). 
(default: 0)


.SS SUN BACKEND PARAMETERS

.TP
\fB\-r, \-\-rate \fIint\fR
Sample rate. 
(default: 48000)

.TP
\fB\-p, \-\-period \fIint\fR
Number of frames between JACK \fBprocess()\fR calls. This
value must be a power of 2. If you need low 
latency, set \fB\-p\fR as low as you can go without seeing xruns. A larger 
period size yields higher latency, but makes xruns less likely. The JACK 
capture latency in seconds is \fB\-\-period\fR divided by \fB\-\-rate\fR. 
(default: 1024)

.TP
\fB\-n, \-\-nperiods \fIint\fR
Number of periods in the hardware buffer. 
The period size (\fB\-p\fR) times \fB\-\-nperiods\fR times four
(assuming 2 channels 16-bit samples) is the JACK buffer size in bytes.
The JACK output latency in seconds is \fB\-\-nperiods\fR times
\fB\-\-period\fR divided by \fB\-\-rate\fR.
(default: 2)

.TP
\fB\-w, \-\-wordlength \fIint\fR
Sample size in bits. 
(default: 16)

.TP
\fB\-i, \-\-inchannels \fIint\fR
Number of capture channels.
(default: 2)

.TP
\fB\-o, \-\-outchannels \fIint\fR
Number of playback channels. 
(default: 2)

.TP
\fB\-C, \-\-capture \fIdevice_file\fR
Input device for capture. 
(default: /dev/audio)

.TP
\fB\-P, \-\-playback \fIdevice_file\fR
Output device for playback. 
(default: /dev/audio)

.TP
\fB\-b, \-\-ignorehwbuf \fIboolean\fR
Whether or not to ignore hardware period size.
(default: false)


.SS PORTAUDIO BACKEND PARAMETERS

.TP
\fB\-c, \-\-channel\fR
Maximum number of channels. 
(default: all available hardware channels)

.TP
\fB\-i, \-\-channelin\fR
Maximum number of input channels. 
(default: all available hardware channels)

.TP
\fB\-I, \-\-input\-latency\fR
Extra input latency (frames). 
(default: 0)

.TP
\fB\-o, \-\-channelout\fR
Maximum number of output channels. 
(default: all available hardware channels)

.TP
\fB\-O, \-\-output\-latency\fR
Extra output latency (frames). 
(default: 0)

.TP
\fB\-C, \-\-capture\fR
Whether or not to capture. 
(default: true)

.TP
\fB\-P, \-\-playback\fR
Whether or not to playback. 
(default: true)

.TP
\fB\-D, \-\-duplex\fR
Capture and playback. 
(default: true)

.TP
\fB\-r, \-\-rate\fR
Sample rate. 
(default: 48000)

.TP
\fB\-p, \-\-period\fR
Frames per period, must be a power of 2. 
(default: 1024)

.TP
\fB\-n, \-\-name\fR
Driver name. 
(default: none)

.TP
\fB\-z, \-\-dither\fR
Dithering mode. 
(default: none)


.SS FIREWIRE BACKEND PARAMETERS

.TP
\fB\-d, \-\-device \fIname\fR
.br
The Firewire device \fIname\fR to use. If none is specified, JACK will try 
to use "hw:0". To get a list of available Firewire devices, see 
\fBffado\-test\fR. It's recommended to use the GUID of a Firewire device 
to rule out any ambiguities. Once the GUID of the device is known 
("ffado-test ListDevices"), it can be used like 
\fB\-dguid:0xff2584e39b078a2e\fR to tell JACK which interface to use.
Sometimes resetting the Firewire bus can help ("ffado-test BusReset") if 
there is any problem.
(default: hw:0)

.TP
\fB\-p, \-\-period \fIint\fR
.br
Number of frames between JACK \fBprocess()\fR calls. This
value must be a power of 2. If you need low latency, set \fB\-p\fR as 
low as you can go without seeing xruns. A larger period size yields higher 
latency, but makes xruns less likely. The JACK capture latency in seconds 
is \fB\-\-period\fR divided by \fB\-\-rate\fR.
(default: 1024)

.TP
\fB\-n, \-\-nperiods \fIint\fR
.br
Number of periods of playback latency. Value must be greater or 
equal 2. In seconds, this corresponds to \fB\-\-nperiods\fR times \fB\-\-period\fR 
divided by \fB\-\-rate\fR.
(default: 3)

.TP
\fB\-r, \-\-rate \fIint\fR
Sample rate.
(default: 48000)

.TP
\fB\-C, \-\-capture\fR [ \fIname\fR ]
Provide only capture ports, unless combined with \-D or \-P. Optionally set 
capture device name.

.TP
\fB\-P, \-\-playback\fR [ \fIname\fR ]
Provide only playback ports, unless combined with \-D or \-C. Optionally set 
playback device name.

.TP
\fB\-D, \-\-duplex\fR
Provide both capture and playback ports. This option is the default behaviour 
and can normally be omitted.
\-D can not be combined with \-P or \-C.

.TP
\fB\-I, \-\-input\-latency\fR
Extra input latency (frames). 
(default: 0)

.TP
\fB\-O, \-\-output\-latency\fR
Extra output latency (frames). 
(default: 0)

.TP
\fB\-v, \-\-verbose
.br
libffado verbose level. 
(default: 3)

.TP
\fB\-X, \-\-snoop\fR 
.br
Snoop Firewire traffic. 
(default: false)

.TP
\fB\-h, \-\-help\fR Print a brief usage message describing only the
\fBfirewire\fR backend parameters.


.SH "EXAMPLES"

.PP
Print usage message for the parameters specific to each backend.

.IP
\fBjackd \-d alsa \-\-help\fR
.br
\fBjackd \-d coreaudio \-\-help\fR
.br
\fBjackd \-d net \-\-help\fR
.br
\fBjackd \-d dummy \-\-help\fR
.br
\fBjackd \-d firewire \-\-help\fR
.br
\fBjackd \-d oss \-\-help\fR
.br
\fBjackd \-d sun \-\-help\fR
.br
\fBjackd \-d portaudio \-\-help\fR
.PP
Run the JACK daemon with realtime priority using the first ALSA
hardware card defined in \fB/etc/modules.conf\fR.

.IP
\fBjackstart \-\-realtime \-\-driver=alsa\fR
.PP
Run the JACK daemon with low latency giving verbose output, which can
be helpful for trouble\-shooting system latency problems. A
reasonably well\-tuned system with a good sound card and a
low\-latency kernel can handle these values reliably. Some can do
better. If you get xrun messages, try a larger buffer. Tuning a
system for low latency can be challenging. Please consult the JACK FAQ
for more suggestions.

.IP
\fBjackstart \-Rv \-d alsa \-p 128 \-n 2 \-r 44100\fR
.PP
Run \fBjackd\fR with realtime priority using the "sblive" ALSA device
defined in ~/.asoundrc. Apply shaped dithering to playback audio.

.IP
\fBjackd \-R \-d alsa \-d sblive \-\-dither=shaped\fR
.PP
Run \fBjackd\fR with no special privileges using the second ALSA
hardware card defined in \fB/etc/modules.conf\fR. Any xruns reported
by the ALSA backend will be ignored. The larger buffer helps reduce
data loss. Rectangular dithering will be used for playback.

.IP
\fBjackd \-d alsa \-d hw:1 \-p2048 \-n3 \-\-softmode \-zr\fR
.PP
Run \fBjackd\fR in full\-duplex mode using the ALSA hw:0,0 device for 
playback and the hw:0,2 device for capture.

.IP
\fBjackd \-d alsa \-P hw:0,0 \-C hw:0,2\fR
.PP
Run \fBjackd\fR in playback\-only mode using the ALSA hw:0,0 device. 

.IP
\fBjackd \-d alsa \-P hw:0,0\fR


.SH "ENVIRONMENT"
.br
JACK is evolving a mechanism for automatically starting the server
when needed. Any client started without a running JACK server will
attempt to start one itself using the command line found in the first
line of \fB$HOME/.jackdrc\fR if it exists, or \fB/etc/jackdrc\fR if it
does not. If neither file exists, a built\-in default command will be
used, including the \fB\-T\fR flag, which causes the server to shut
down when all clients have exited.

As a transition, this only happens when \fB$JACK_START_SERVER\fR is
defined in the environment of the calling process. In the future this
will become normal behavior. In either case, defining
\fB$JACK_NO_START_SERVER\fR disables this feature.

To change where JACK looks for the backend drivers, set
\fB$JACK_DRIVER_DIR\fR.

\fB$JACK_DEFAULT_SERVER\fR specifies the default server name. If not
defined, the string "default" is used. If set in their respective
environments, this affects \fBjackd\fR unless its \fB\-\-name\fR
parameter is set, and all JACK clients unless they pass an explicit
name to \fBjack_client_open()\fR.

Defining \fB$JACK_NO_AUDIO_RESERVATION\fR will bypass audio device
reservation via session bus (DBus). This can be useful if JACK
was compiled with DBus support but should run on a headless system.

\fB$JACK_PROMISCUOUS_SERVER\fR enables an alternate way of handling the various
shared resources (Unix sockets, semaphores, ...). In this mode, the generated
names will not contain the user id anymore, and the permissions of those
resources will be relaxed, allowing clients from different users to talk with
the same server. Moreover, on platforms that support it (all POSIX variants),
if set to a valid Unix group name or id, the permissions will be restricted to
that group, so only members of that group will be able to launch clients that
talk to this server. Important note: it must be set with the same value for
both server and clients to work as expected.

.SH "SEE ALSO:"
.PP
<\fBhttp://www.jackaudio.org/\fR>
.br
The official JACK website with news, docs and a list of JACK clients.
.PP
<\fBhttp://www.github.com/jackaudio/\fR>
.br
The official JACK github code repository. Pull requests are welcome.
.PP
<\fBhttp://lists.jackaudio.org/listinfo.cgi/jack-devel-jackaudio.org\fR>
.br
The JACK developers' mailing list. Subscribe to take part in
development of JACK or JACK clients. User questions are also welcome,
there is no user-specific mailing list.
.PP
<\fBhttp://www.jackosx.com/\fR>
.br
Tools specific to the Mac OS X version of JACK.
.PP
<\fBhttp://www.alsa\-project.org/\fR>
.br
The Advanced Linux Sound Architecture.
.PP
<\fBhttp://www.ffado.org/\fR>
.br
The Free Firewire Audio Drivers (FFADO) Site.
.PP
<\fBirc.freenode.net#jack\fR>
.br
Join the JACK community with your favourite IRC client.


.SH "BUGS"
Please report bugs as issues to the corresponding repository:
.br
<\fBhttp://www.github.com/jackaudio/\fR>


.SH "AUTHORS"
Architect and original implementer: Paul Davis
.PP
Original design group: Paul Davis, David Olofson, Kai Vehmanen, Benno Sennoner,
Richard Guenther and other members of the Linux Audio Developers group.
.PP
Programming: Paul Davis, Jack O'Quin, Taybin Rutkin, Stéphane Letz, Fernando
Pablo Lopez-Lezcano, Steve Harris, Jeremy Hall, Andy Wingo, Kai
Vehmanen, Melanie Thielker, Jussi Laako, Tilman Linneweh, Johnny
Petrantoni, Torben Hohn.
.PP
Manpage written by Stefan Schwandter, Jack O'Quin, Alexandre Prokoudine and Thomas Brand.
.PP
Create a PDF file from this manpage:
.IP
\fBman -t jackd | ps2pdf - > jackd.pdf\fR