Provided by: jackd2_1.9.21~dfsg-3_amd64 bug

NAME

       jackd - JACK Audio Connection Kit sound server

SYNOPSIS

       jackd [options] -d backend [backend-parameters]
       jackd --help

DESCRIPTION

       jackd  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 jackd 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. JACK Audio Connection Kit.

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

OPTIONS

       -d, --driver backend [backend-parameters ]
              Select  the  audio  interface  backend.  The current list of supported backends is:
              alsa, coreaudio, dummy, firewire, oss sun and portaudio. They are not all available
              on all platforms. All backend-parameters are optional.

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

       -a, --autoconnect modechar
              Select how to handle self connect requests. They can be ignore or fail, on all port
              or just external ones. Use the --help option to know your system specific  options.
              The default is to not restrict self connect requests.

       -m, --no-mlock
              Do not attempt to lock memory, even if --realtime.

       -n, --name server-name
              Name  this  jackd  instance  server-name.  If unspecified, this name comes from the
              $JACK_DEFAULT_SERVER environment variable.  (default: "default")

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

       --replace-registry
              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).

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

       -r, --no-realtime
              Do not use realtime scheduling.

       -P, --realtime-priority int
              When running --realtime, set the scheduler priority to int.

       --silent
              Silence any output during operation.

       -T, --temporary
              Exit once all clients have closed their connections.

       -t, --timeout int
              Set client timeout limit in milliseconds.  In realtime mode the client timeout must
              be smaller than the watchdog timeout (5000 msec).  (default: 500)

       -Z, --nozombies
              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.

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

       -u, --unlock
              Unlock libraries GTK+, QT, FLTK, Wine.

       -v, --verbose
              Give verbose output.

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

       -V, --version
              Print the current JACK version number and exit.

   ALSA BACKEND OPTIONS
       -C, --capture [ name ]
              Provide  only  capture ports, unless combined with -D or -P. Optionally set capture
              device name.

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

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

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

       -h, --help Print a brief usage message describing only the
              alsa backend parameters.

       -M, --hwmeter
              Enable  hardware  metering  for  devices  that  support it. Otherwise, use software
              metering.

       -H, --hwmon
              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  --hwmon.  In
              the  future,  some  consumer  cards  may also be supported by modifying their mixer
              settings.

              Without --hwmon, 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 --period and --nperiods parameters.

       -i, --inchannels int
              Number of capture channels.  (default: maximum supported by hardware)

       -I, --input-latency
              Extra input latency (frames).  (default: 0)

       -n, --nperiods int
              Number of periods of playback latency. In seconds, this corresponds  to  --nperiods
              times  --period  divided by --rate. The default is 2, the minimum allowed. For most
              devices, there is no need for any other value with the --realtime  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 --period times --nperiods
              frames. Some devices demand a larger buffer. If so,  JACK  will  use  the  smallest
              possible  buffer  containing at least --nperiods, but the playback latency does not
              increase.

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

       -o, --outchannels int
              Number of playback channels.  (default: maximum supported by hardware)

       -O, --output-latency
              Extra output latency (frames).  (default: 0)

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

       -p, --period int
              Number of frames between JACK process() calls. This value must be a power of 2.  If
              you  need  low  latency, set -p 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 --period divided by --rate.  (default: 1024)

       -r, --rate int
              Sample rate.  (default: 48000)

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

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

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

   COREAUDIO BACKEND PARAMETERS
       -c, --channels
              Maximum number of channels.  (default: 2)

       -i, --inchannels
              Maximum number of input channels.  (default: 2)

       -o, --outchannels
              Maximum number of output channels.  (default: 2)

       -C, --capture
              Whether or not to capture.  (default: true)

       -P, --playback
              Whether or not to playback.  (default: true)

       -D, --monitor
              Provide monitor ports for the output.  (default: false)

       -D, --duplex
              Capture and playback.  (default: true)

       -r, --rate
              Sample rate.  (default: 44100)

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

       -d, --device
              CoreAudio device name.  (default: none)

       -I, --input-latency
              Extra input latency (frames).  (default: 0)

       -O, --output-latency
              Extra output latency (frames).  (default: 0)

       -l, --list-devices
              Display available CoreAudio devices.  (default: false)

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

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

       -G, --grain
              Computation grain in RT thread (percent).  (default: 100)

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

   DUMMY BACKEND PARAMETERS
       -C, --capture int
              Number of capture ports.  (default: 2)

       -P, --playback int
              Number of playback ports.  (default: 2)

       -r, --rate int
              Sample rate.  (default: 48000)

       -p, --period int
              Number  of frames between JACK process() calls. This value must be a power of 2. If
              you need low latency, set -p 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 --period divided by --rate.  (default: 1024)

       -w, --wait int
              Number of usecs to wait between engine processes.  (default: 21333)

   NETONE BACKEND PARAMETERS
       -i, --audio-ins int
              Number of capture channels.  (default: 2)

       -o, --audio-outs int
              Number of playback channels.  (default: 2)

       -I, --midi-ins int
              Number of midi capture channels.  (default: 1)

       -O, --midi-outs int
              Number of midi playback channels.  (default: 1)

       -r, --rate int
              Sample rate.  (default: 48000)

       -p, --period int
              Frames per period.  (default: 1024)

       -n, --num-periods int
              Network latency setting in no. of periods.  (default: 5)

       -l, --listen-port int
              The socket port we are listening on for sync packets.  (default: 3000)

       -f, --factor int
              Factor for sample rate reduction.  (default: 1)

       -u, --upstream-factor int
              Factor for sample rate reduction on the upstream.  (default: 0)

       -c, --celt int
              Sets celt encoding and number of kbits per channel.  (default: 0)

       -b, --bit-depth int
              Sample bit-depth (0 for float, 8 for 8bit and 16 for 16bit).  (default: 0)

       -t, --transport-sync int
              Whether or not to slave the transport to the master transport.  (default: true)

       -a, --autoconf int
              Whether or not to use Autoconfig, or just start.  (default: true)

       -R, --redundancy int
              Send packets N times.  (default: 1)

       -e, --native-endian int
              Don't convert samples to network byte order.  (default: false)

       -J, --jitterval int
              Attempted jitterbuffer microseconds on master.  (default: 0)

       -D, --always-deadline int
              Always use deadline.  (default: false)

   OSS BACKEND PARAMETERS
       -r, --rate int
              Sample rate.  (default: 48000)

       -p, --period int
              Number of frames between JACK process() calls. This value must be a power of 2.  If
              you  need  low  latency, set -p 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 --period divided by --rate.  (default: 1024)

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

       -w, --wordlength int
              Sample size in bits.  (default: 16)

       -i, --inchannels int
              Number of capture channels.  (default: 2)

       -o, --outchannels int
              Number of playback channels.  (default: 2)

       -C, --capture device_file
              Input device for capture.  (default: /dev/dsp)

       -P, --playback device_file
              Output device for playback.  (default: /dev/dsp)

       -b, --ignorehwbuf boolean
              Whether or not to ignore hardware period size.  (default: false)

       -e, --excl boolean
              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)

       -I, --input-latency
              Extra input latency (frames).  (default: 0)

       -O, --output-latency
              Extra output latency (frames).  (default: 0)

   SUN BACKEND PARAMETERS
       -r, --rate int
              Sample rate.  (default: 48000)

       -p, --period int
              Number  of frames between JACK process() calls. This value must be a power of 2. If
              you need low latency, set -p 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 --period divided by --rate.  (default: 1024)

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

       -w, --wordlength int
              Sample size in bits.  (default: 16)

       -i, --inchannels int
              Number of capture channels.  (default: 2)

       -o, --outchannels int
              Number of playback channels.  (default: 2)

       -C, --capture device_file
              Input device for capture.  (default: /dev/audio)

       -P, --playback device_file
              Output device for playback.  (default: /dev/audio)

       -b, --ignorehwbuf boolean
              Whether or not to ignore hardware period size.  (default: false)

   PORTAUDIO BACKEND PARAMETERS
       -c, --channel
              Maximum number of channels.  (default: all available hardware channels)

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

       -I, --input-latency
              Extra input latency (frames).  (default: 0)

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

       -O, --output-latency
              Extra output latency (frames).  (default: 0)

       -C, --capture
              Whether or not to capture.  (default: true)

       -P, --playback
              Whether or not to playback.  (default: true)

       -D, --duplex
              Capture and playback.  (default: true)

       -r, --rate
              Sample rate.  (default: 48000)

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

       -n, --name
              Driver name.  (default: none)

       -z, --dither
              Dithering mode.  (default: none)

   FIREWIRE BACKEND PARAMETERS
       -d, --device name
              The Firewire device name to use. If none is specified, JACK will try to use "hw:0".
              To get a list of available Firewire devices, see ffado-test.  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
              -dguid:0xff2584e39b078a2e 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)

       -p, --period int
              Number  of frames between JACK process() calls. This value must be a power of 2. If
              you need low latency, set -p 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 --period divided by --rate.  (default: 1024)

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

       -r, --rate int
              Sample rate.  (default: 48000)

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

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

       -D, --duplex
              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.

       -I, --input-latency
              Extra input latency (frames).  (default: 0)

       -O, --output-latency
              Extra output latency (frames).  (default: 0)

       -v, --verbose
              libffado verbose level.  (default: 3)

       -X, --snoop
              Snoop Firewire traffic.  (default: false)

       -h, --help Print a brief usage message describing only the
              firewire backend parameters.

EXAMPLES

       Print usage message for the parameters specific to each backend.

              jackd -d alsa --help
              jackd -d coreaudio --help
              jackd -d net --help
              jackd -d dummy --help
              jackd -d firewire --help
              jackd -d oss --help
              jackd -d sun --help
              jackd -d portaudio --help

       Run  the  JACK daemon with realtime priority using the first ALSA hardware card defined in
       /etc/modules.conf.

              jackstart --realtime --driver=alsa

       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.

              jackstart -Rv -d alsa -p 128 -n 2 -r 44100

       Run jackd with realtime priority using the "sblive" ALSA device  defined  in  ~/.asoundrc.
       Apply shaped dithering to playback audio.

              jackd -R -d alsa -d sblive --dither=shaped

       Run  jackd  with  no  special  privileges  using  the second ALSA hardware card defined in
       /etc/modules.conf. Any xruns reported by the ALSA backend  will  be  ignored.  The  larger
       buffer helps reduce data loss. Rectangular dithering will be used for playback.

              jackd -d alsa -d hw:1 -p2048 -n3 --softmode -zr

       Run  jackd  in  full-duplex  mode using the ALSA hw:0,0 device for playback and the hw:0,2
       device for capture.

              jackd -d alsa -P hw:0,0 -C hw:0,2

       Run jackd in playback-only mode using the ALSA hw:0,0 device.

              jackd -d alsa -P hw:0,0

ENVIRONMENT

       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 $HOME/.jackdrc if it exists, or /etc/jackdrc  if  it  does
       not.  If  neither  file  exists, a built-in default command will be used, including the -T
       flag, which causes the server to shut down when all clients have exited.

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

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

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

       Defining  $JACK_NO_AUDIO_RESERVATION  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.

       $JACK_PROMISCUOUS_SERVER 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.

SEE ALSO:

       <http://www.jackaudio.org/>
       The official JACK website with news, docs and a list of JACK clients.

       <http://www.github.com/jackaudio/>
       The official JACK github code repository. Pull requests are welcome.

       <http://lists.jackaudio.org/listinfo.cgi/jack-devel-jackaudio.org>
       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.

       <http://www.jackosx.com/>
       Tools specific to the Mac OS X version of JACK.

       <http://www.alsa-project.org/>
       The Advanced Linux Sound Architecture.

       <http://www.ffado.org/>
       The Free Firewire Audio Drivers (FFADO) Site.

       <irc.freenode.net#jack>
       Join the JACK community with your favourite IRC client.

BUGS

       Please report bugs as issues to the corresponding repository:
       <http://www.github.com/jackaudio/>

AUTHORS

       Architect and original implementer: Paul Davis

       Original  design  group:  Paul Davis, David Olofson, Kai Vehmanen, Benno Sennoner, Richard
       Guenther and other members of the Linux Audio Developers group.

       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.

       Manpage written by Stefan Schwandter, Jack O'Quin, Alexandre Prokoudine and Thomas Brand.

       Create a PDF file from this manpage:

              man -t jackd | ps2pdf - > jackd.pdf