mpvipc
======

mpvipc - send IPC commands to one mpv instance or multiple of them (on Linux)

Usage examples:
 mpvipc -v '{ "command": ["get_property", "track-list"] }'
 mpvipc '{ "command": ["cycle-values", "osd-level", "2", "3", "1"] }'
 mpvipc 'show-text ${media-title} 10000'

This assumes a well defined directory where the sockets of all running mpv
instances can be found. The default value is $HOME/.config/mpv/socket but it
can be modified by command line option. Myself, I always run mpv through a
script wrapper to ensure consistent behavior.

Another example, lua code:
 function on_mute_change(name, value)
   if value == false then
     local socket = mp.get_property('input-ipc-server')
     local cmd = [[{ "command": ["set_property", "mute", true] }]]
     if socket ~= '' then
       os.execute(("mpvipc -e %s %q"):format(socket, cmd))
     end
   end
 end
 mp.observe_property("mute", "bool", on_mute_change)

This way, each time an instance is un-muted all other instances are muted.
Obviously useful when you don't appreciate multiple instances babbling at the
same time.

Other usage examples are mpv key bindings that control all running mpv
instances. Like an Alt+q binding to quit them all. Or at-jobs to start/stop
recordings.

Options:
 -v verbose - the program is written to produce zero output per default
 -d debug   - extra diagnostics regarding IPC communication and socket polling
 -e exclude - exclude this socket from operation; basename or full path
 -i include - the opposite; operate on this socket only; basename or full path
 -p path    - path to socket directory; absolute or relative to HOME

Compile like this:
 clang mpvipc.c -o mpvipc
or with gdb if you like, same options.

Then start all your mpv instances with script code like this:
 home=$HOME
 mpv=/usr/bin/mpv
 socket_dir=$home/.config/mpv/socket
 socket=${socket_dir}/$$
 exec $mpv --input-ipc-server="$socket" "$@"
and make sure socket_dir exists. This way, each instance has an IPC socket in
that directory with name equal to its PID (that's why we need the exec). Which
makes it easier to identify individual instances programmatically, like by doing
grep's on command line options of 'ps' output.

The program unlinks sockets where it gets a "connection refused" by the way. So
if you actually use it regularly there's no need to otherwise clean up the
socket directory.