Provided by: jackd2_1.9.12~dfsg-2build1_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.

       -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.

       -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.   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
              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
              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().

       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://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.