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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, a low-latency audio server.
       Originally written for the GNU/Linux operating system, it also supports
       Mac  OS  X  and  various  Unix platforms.  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.

       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, freebob, 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.

       -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.  It
              will be "default" if that is not defined.

       -p, --port-max  n
              Set the maximum number of ports the JACK server can manage.  The
              default value is 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  (default  = true). 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.

       -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.  The  default  is  500
              msec.   In realtime mode the client timeout must be smaller than
              the watchdog timeout (5000 msec).

       -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.

       -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.
              Parameterally 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.

       -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  is  maximum  supported  by
              hardware.

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

       -n, --nperiods int
              Specify  the number of periods of playback latency.  In seconds,
              this corresponds to --nperiods times --period divided by --rate.
              The  default  is  2,  the  minimum allowable.  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 is 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
              Specify the number of frames between JACK process() calls.  This
              value must be a power of 2, and the default  is  1024.   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.

       -r, --rate int
              Specify the sample rate.  The default is 48000.

       -S, --shorts
              Try to configure card for  16-bit  samples  first,  only  trying
              32-bits if unsuccessful.  Default is to prefer 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]
              Specify  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 (default: 128). Must be a power of 2.

       -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   to  compensate  clock  drift  in  dynamically  created
              aggregate device (default: false)

   DUMMY BACKEND PARAMETERS
       -C, --capture int
              Specify number of capture ports. The default value is 2.

       -P, --playback int
              Specify number of playback ports. The default value is 2.

       -r, --rate int
              Specify sample rate. The default value is 48000.

       -p, --period int
              Specify the number of frames between JACK process() calls.  This
              value  must  be  a  power of 2, and the default is 1024.  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.

       -w, --wait int
              Specify  number  of usecs to wait between engine processes.  The
              default value is 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 to slave the transport to the master transport (default:
              true)

       -a, --autoconf int
              Whether to use Autoconfig, or just start. (default: true)

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

       -e, --native-endian int
              Dont 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
              Specify the sample rate.  The default is 48000.

       -p, --period int
              Specify the number of frames between JACK process() calls.  This
              value must be a power of 2, and the default  is  1024.   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.

       -n, --nperiods int
              Specify the number of  periods  in  the  hardware  buffer.   The
              default  is 2.  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.

       -w, --wordlength int
              Specify the sample size in bits. The default is 16.

       -i, --inchannels int
              Specify how many channels to capture (default: 2)

       -o, --outchannels int
              Specify number of playback channels (default: 2)

       -C, --capture device_file
              Specify input device for capture (default: /dev/dsp)

       -P, --playback device_file
              Specify output device for playback (default: /dev/dsp)

       -b, --ignorehwbuf boolean
              Specify, whether to ignore hardware period size (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
              Specify the sample rate.  The default is 48000.

       -p, --period int
              Specify the number of frames between JACK process() calls.  This
              value must be a power of 2, and the default  is  1024.   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.

       -n, --nperiods int
              Specify the number of  periods  in  the  hardware  buffer.   The
              default  is 2.  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.

       -w, --wordlength int
              Specify the sample size in bits. The default is 16.

       -i, --inchannels int
              Specify how many channels to capture (default: 2)

       -o, --outchannels int
              Specify number of playback channels (default: 2)

       -C, --capture device_file
              Specify input device for capture (default: /dev/audio)

       -P, --playback device_file
              Specify output device for playback (default: /dev/audio)

       -b, --ignorehwbuf boolean
              Specify, whether 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 (default: 1024). Must be a power of 2.

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

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

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 freebob --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.   The JACK FAQ, http://jackit.sourceforge.net/docs/faq.php
       has some useful 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().

SEE ALSO:

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

       http://jackaudio.org/email
       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.

BUGS

       Please report bugs to
       http://trac.jackaudio.org/

AUTHORS

       Architect and original implementor: 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, Stephane 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  and  Alexandre
       Prokoudine.



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