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PLAYLISTFS(7)          Miscellaneous Information Manual          PLAYLISTFS(7)



NAME
       playlistfs - playlist file system

SYNOPSIS
       games/playlistfs [ -s postname ] [ -m mountpoint ] [ -a ]

DESCRIPTION
       Playlistfs implements an audio player which plays files from a built-in
       play list.  The player  is  controlled  through  three  files,  usually
       mounted  at  /mnt.  The files are /playctl for controlling play: start,
       stop, pause, skip, etc.; /playvol for controlling the  playout  volume;
       and /playlist for controlling the play list itself.

       All three files can be written to control the player and read to obtain
       player status information.

       When read, the files report the current status of  the  player,  volume
       and  playlist,  respectively.   End of file is indicated by a read that
       returns zero bytes, as usual.  However, in all three files,  subsequent
       read  operations  will  block  until the status of the file changes and
       then report the changed state.  When the changed state has  been  read,
       another  end-of-file  indication is given, after which another read can
       be issued to wait for state changes.

       The /playctl file returns strings of the form `cmd n' where cmd is  one
       of  stop,  pause,  or  play  and  n  is  an  index (or offset) into the
       playlist; indices start at zero.

       The commands that can be written to /playctl take the same  form;  how‐
       ever,  the index is an optional argument.  If the index is omitted, the
       current value is used. The commands are play, stop, pause, resume,  and
       skip.   Play  starts  playing at the index.  Stop stops playing.  If an
       index is given, the current index is set to it and can be used  in  fu‐
       ture  commands.   Pause and Resume interrupt and continue play, respec‐
       tively.  The index argument is always ignored and the whole command  is
       ignored  if  the  state  in which they occur does not make sense.  Skip
       adds the argument to the current index (adds  one  if  no  argument  is
       given)  and starts play at that index, stopping current play, if neces‐
       sary.

       Reads of /playvol return strings of the form `volume n', where n  is  a
       number  or, if there is more than one channel, a quoted set of numbers,
       between 0 (minimum) and 100 (maximum).  Writes  to  /playvol  take  the
       same form.

       The  /playlist file is an append-only file which accepts lines with one
       or two fields per line (parsed using tokenize).  The first, compulsory,
       field is a file name, the optional second argument may contain a refer‐
       ence to, or a description of, the item, for  instance  in  a  graphical
       user  interface.   /playlist is append-only, individual lines cannot be
       removed.  However, the playlist can be cleared by opening the file with
       the  OTRUNC  flag.  A process that has /playlist open while the file is
       truncated will receive an error on the next read  with  errstr  set  to
       reading  past eof.  When this error occurs, clients can seek to the be‐
       ginning of the file and reread its contents.

       After starting up, Playlistfs  puts  itself  in  the  background.  When
       called  with  the  -s  flag,  it  posts  a mountable file descriptor in
       /srv/playlist.postname.  The -m flag can be used  to  specify  a  mount
       point other than /mnt.

       The files to be played are recognized by one of four extensions, and an
       appropriate player is then selected to play them.  Files without a rec‐
       ognized extension are played by the pac player:

       .mp3   /bin/games/mp3dec

       .pac   /bin/games/pac4dec

       .pcm   /bin/cp

       .ogg   /bin/games/vorbisdec

FILES
       /srv/playlistfs.user: default playlistfs mountable file descriptor used
       by juke(7).
       /mnt/playctl: Control file
       /mnt/playlist: Playlist file
       /mnt/playvol: Volume control file

SOURCE
       /sys/src/games/music/playlistfs

SEE ALSO
       juke(7), audio(7)



                                                                 PLAYLISTFS(7)