Provided by: jackd1_0.124.1+20140122git5013bed0-3build2_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, 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.

       -A device, -A device%p, -A device%c
              (Linux-only) A simplified way to add additional audio I/O hardware to  an  instance
              of  JACK.  This argument is actually just a wrapper around the -I (internal client)
              version, requiring only the name of the ALSA "card" to be used. The name should NOT
              include  any  ALSA device access prefix (e.g. "hw:" or "plughw:") but can include a
              subdevice. If %p is added to the  device  name,  it  will  be  made  available  for
              playback  only.  If  %c  is added to the device name, it will be made available for
              capture (recording) only. If neither %p nor %c is added, it will be made  available
              (if  possible)  for both capture and playback. Although device names may be visible
              in various places on your system, the file  /proc/asound/cards  shows  them  inside
              square braces.
              Examples:
              -A SB   (adds playback and capture for the "SB" device)
              -A  Codec,1%c   (adds  capture  (recording)  for  the  2nd subdevice of the "Codec"
              device)
              -A MT1a2%p   (adds playback the 1st subdevice of the "MT1a2" device)
              The use of -A CARD is actually  equivalent  to  -I  foo:zalsa_in/-dhw:CARD  and  -I
              CARD:zalsa_out/-dhw:CARD.
              The use of -A CARD%p is actually equivalent to  -I CARD:zalsa_out/-dhw:CARD.
              The use of -A CARD%c is actually equivalent to -I CARD:zalsa_in/-dhw:CARD
              Note that this option (like -I) can be used regardless of the backend used, so even
              if you do not use the ALSA backend, you can still add ALSA-supported devices to  an
              instance of JACK.

       -I, --internal-client client-spec
              Load  client-name  as  an  internal client. May be used multiple times. The form of
              client-spec can be any of the following:
              client-path
              client-name:client-path
              client-name:client-path/init-string
              client-path/init-string
              The first form will cause jackd to attempt to load the client from a shared  object
              named  "client-path"  with  appropriate  suffixes  appended.  If  "client-path"  is
              absolute, jackd will use that (adding a platform appropriate suffix  for  a  shared
              object).  If  it  is  not  absolute,  jackd  will  look  for "client-path" (with an
              appropriate suffix) in the same location that drivers and other  JACK  add-ons  are
              located.
              The  second  form  provides  "client-name"  as the desired name for the client once
              loaded, in addition to the "client-path".
              The third form provides an "init-string" in addition to a  client  name  and  path,
              which will be passed to the client's initialization function.
              The  final  form does not specify the client name, but does include the path to the
              client's shared object file and an initializations string.
              When invoking JACK from the shell, remember to quote  the  argument  to  -I  if  it
              includes spaces.

       -M, --midi-bufsize [ event-count ]
              Specify  the  size  of  the  buffer used for MIDI ports. Units are "MIDI events per
              process() cycle", where an event occupies up to 4 bytes (as most common MIDI events
              do).  The  default  buffer  size  is  2048  bytes,  which is about 500 MIDI events.
              Typical values for event-count will range from 10 to  about  1000.  Be  aware  that
              using  very  high values along with a large number of ports may  cause JACK to fail
              to start because of the amount of memory that would be required.

       -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.

       -S, --sync
              This option does nothing in this implementation of JACK, but  exists  for  command-
              line compatibility with JACK2 and possibly other versions.

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

       -t, --timeout int
              Set client timeout limit in milliseconds.  The default is 500 msec.

       -X, --slave-driver driver-name
              Asks  the server to load the "slave" driver given by driver-name. Slave drivers can
              provide builtin-access to other devices and protocols; the primary slave-driver  at
              this  time  is  the "alsa_midi" one which provides bridging on Linux between native
              ALSA MIDI and JACK MIDI.

       -Z, --nozombies
              Prevent JACK from ever kicking out  clients  because  they  were  too  slow.   This
              cancels the effect any specified timeout value.

       -C, --timeout-thres time
              Stop  processing  clients  if  JACK  cannot  complete  the  process  cycle  in time
              (typically caused by CPU overloading or  misbehaved  clients).  The  optional  time
              argument  specifies  the  number  of miliseconds, during which consectutive process
              cycles must fail before JACK gives up (if the argument is not given, it defaults to
              250).  Processing  will resume on the next change to the port graph (i.e. a port is
              added, removed, connected or disconnected)

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

       -v, --verbose
              Give verbose output.

       -c, --clocksource ( c(ycle) |  h(pet)  |  s(ystem) )
              Select a specific wall clock (Cycle Counter, 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.

       -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.

       -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
              Provide bridging between ALSA MIDI and JACK MIDI (using the ALSA sequencer system).
              All ALSA MIDI clients and MIDI hardware  that  exist  when  jackd  starts  will  be
              represented by JACK MIDI ports.
              The  "seq"  argument  has  been  retained  from  older versions of JACK, in part to
              provide for the possibility of alternate implementations.

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

       -i --channelin
              Maximum number of input channels (default: 2)

       -o --channelout
              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 --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.

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

       -I --id
              Audio Device ID (default: 0)

   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.

   NET 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)

   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)

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

       -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.