Provided by: zita-njbridge_0.4.1-1_amd64 bug

NAME

       zita-j2n,  zita-n2j - Jack clients to transport multichannel audio over
       a local network.

SYNOPSIS

       zita-j2n [ options ] ip-address ip-port
       zita-n2j [ options ] ip-address ip-port
       zita-j2n [ options ] ip-address ip-port interface
       zita-n2j [ options ] ip-address ip-port interface

DESCRIPTION

   General
       The zita-j2n (sender) and zita-n2j  (receiver)  applications  allow  to
       exchange  up  to 64 channels of full-quality uncompressed audio streams
       between two or more systems running the Jack audio server.  Sender  and
       receiver(s) can each have their own sample rate and period size, and no
       word clock sync between them is assumed.  The  receiver  uses  adaptive
       resampling to convert the audio stream(s) to its local sample rate.

       There  is  no master/slave relationship between sender and receiver(s).
       This is an explicit design goal. In all  respects  the  net  result  of
       using  zita-njbridge  is  similar  to  having  analog audio connections
       between the sound cards of the systems using it. Nothing a  sender  can
       do  will  affect  the  receiver(s),  apart from the audio signals being
       available or reverting to silence if  there  is  no  sender.  Xruns  or
       skipped  cycles will not affect the synchronisation or resampling. Jack
       freewheeling on either end will temporarily suspend operation.

       Zita-njbridge can be used in  two  ways:  one-to-one,  or  one-to-many.
       Both IPv4 and IPv6 are supported.

       For  a  one-to-one  setup  the  first  form of the commands shown above
       should be used. The protocol used is UDP and  the  ip-address  argument
       required  for  both sender and receiver is that of the receiver. A host
       name can be used instead of a numerical  IP  addresses,  this  will  be
       looked up using getaddrinfo().

       For  a  one-to-many  setup  the second form must be used The ip-address
       argument should  be  a  valid  multicast  address,  and  the  mandatory
       interface argument selects the network interface to be used.

   Resampler filter length.
       The receiver uses the zita-resampler library to resample signals to its
       local rate. The length of the multiphase low-pass filter used  as  part
       of the resampling algorithm determines the audio bandwidth, and adds to
       latency. It can also have a significant impact  on  CPU  load  if  many
       channels are received.

       Zita-njbridge  will  select  a  filter length based on the lower of the
       sender and receiver sample rates. For sample  rates  of  44.1  Khz  and
       above  the  value  chosen will result in an attenuation of no more than
       0.1 dB up to 20 kHz. The --filt  option  allows  one  to  override  the
       automatic configuration, but this will normally not be necessary.

   Latency issues.
       When  connecting  two  Jack  systems  with  unsynchronised  periods the
       minimum additional latency under worst case conditions is  the  sum  of
       the  two period times. Additional latency means any latency required to
       make the connection work without interruption.  The round-trip  latency
       from  an  ideal  (zero excess latency) analog input on the sender to an
       ideal (idem) analog output on the receiver will be  twice  this  value.
       Worst  case  conditions means that the both sender and receiver can run
       at arbitrary times within their respective periods.

       Zita-njbridge is designed to provide a defined and constant  additional
       latency.  The  target  value  is  the  sum  of  the  two  periods, plus
       resampling delay, plus any extra buffering specified by the  user.  The
       actual  latency  will be this value plus the average network delay. The
       latter is unknown so there is no way to compensate for it.  This  would
       be  possible  using either a return channel, or some way to sync clocks
       on the two systems which could then be  used  to  measure  the  average
       network  delay.  The  current release of zita-njbridge does not provide
       this as it is meant for use on a local network. A dedicated or  lightly
       loaded gigabit Ethernet can provide typical network delays well below a
       millisecond.

       The --buff option of zita-n2j adds the specified number of milliseconds
       to  the  target  latency. The default value is 10 ms which is more than
       enough on a moderately loaded Gigabit local network. This can be set to
       zero, for example when it is known that the sender will always run near
       the start of its Jack period and the network delay jitter is less  than
       this period.

       If  there  is any network delay jitter above 10ms, increasing the extra
       buffer time will be necessary to avoid occasional interruption  of  the
       received audio streams.

       The  latency does not depend on the when exactly the sender runs within
       its Jack period. This is similar to playback to a soundcard:  when  the
       playback  samples  are  written  well before they are due this does not
       decrease the latency, the data is just buffered until the  end  of  the
       period.  In  the  case of zita-njbridge the remaining time is available
       for network delay. This is why, when the sender is only lightly  loaded
       and  network  delay  is  small,  it  is possible to use --buff 0 at the
       receivers.

   Use on wide area or wireless networks.
       The current implementation is designed to be  used  on  local  networks
       that  provide  more  or  less reliable delivery of packets, with low or
       moderate  delay.  Occasional  lost  packets   will   not   impact   the
       synchronisation  or  resampling,  but any samples arriving out of order
       will be ignored (they will have been replaced by silence before). Extra
       buffering  (using the --buff option) will allow an uninterrupted signal
       in the presence of delay jitter, at the price  of  additional  latency.
       Zita-njbridge  may be usable on long distance internet connections, but
       keep in mind it was not designed for this.

       Performance on wireless networks is purely a matter  of  chance.  Again
       zita-njbridge is not designed for such use.

OPTIONS

   Common options
       --help
              Print command line and options summary.

       --jname name
              Select  the  Jack  client  client name. Default is 'zita-j2n' or
              'zita-n2j'.

       --jserv server
              Select the Jack server to connect to.

   zita-j2n options
       --chan channels
              The number of channels to transmit, the default is 2 channels.

       --16bit
              Send audio as 16-bit signed integer samples.

       --24bit
              Send audio as 24-bit signed integer samples. This is the default
              format.

       --float
              Send  audio  as  32-bit  floating point samples (Jack's internal
              format).

       --mtu MTU
              Inform zita-j2n of the path MTU, allowing it to use  packets  up
              to  that  size.  The  default value is 1500. Note that large MTU
              values on a shared network may increase network delay jitter.

       --hops hops
              Set the maximum number of hops for multicast packets.   Defaults
              to one, i.e. multicast is to the local net only.

   zita-n2j options
       --chan list
              A  list  of channels numbers in ascending order and separated by
              comma  or  dash  characters,  the  latter  indicating  a  range.
              Channel  numbers start at 1. Only the requested channels will be
              resampled and have  a  corresponding  Jack  port.  Channels  not
              provided  by the sender will output silence. The default channel
              list is '1,2'.

       --buff time
              Increase the target latency by the given time, in  milliseconds.
              The default is 10 ms. See the description above for what exactly
              this means.

       --filt delay
              Set the resampler filter delay, in samples at the lower  of  the
              two sample rates, in the range 16..96. See above for details.

       --info
              Print  additional  diagnostic  information. Three values will be
              printed twice per second: The  average  resampler  control  loop
              error  in frames, the resampler ratio correction factor, and the
              minimum number of frames available in the receive buffer.

AUTHOR

       zita-j2n, zita-n2j and this manual page were written by Fons Adriaensen
       <fons@linuxaudio.org>.

                                   July 2014                  ZITA-NJBRIDGE(1)