Synchronized playback over a network

Description source: http://www.mplayerhq.hu/DOCS/HTML/en/networksync.html

Multiple instances of MPlayer can synchronize playback over a network. This is useful for creating "video walls" with multiple screens controlled by different computers. Each MPlayer instance can play a different video, but they all will try to stay at the same time offset in the file. It is recommended but not necessary to encode the video files using the same codec and parameters.

The relevant options are -udp-master, -udp-slave, -udp-ip, -udp-port, and -udp-seek-threshold.

If -udp-master is given, MPlayer sends a datagram to -udp-ip (default: 127.0.0.1) on -udp-port (default: 23867) just before playing each frame. The datagram indicates the master's position in the file. If -udp-slave is given, MPlayer listens on -udp-ip/-udp-port and matches the master's position. Setting -udp-ip to the master's broadcast address allows multiple slaves having the same broadcast address to sync to the master. Note that this feature assumes an ethernet-like low-latency network connection. Your mileage may vary on high latency networks.

Mentioned on issue #898.

Also on https://github.com/mpv-player/mpv/issues/252#issuecomment-24864050.

Start by reviewing the linked MPlayer network-sync documentation and the related issue references, then locate how mpv handles command-line options and playback timing. Done means implementing the -udp-master, -udp-slave, -udp-ip, -udp-port, and -udp-seek-threshold behavior so multiple instances can synchronize playback over a network.