Synced display of multicast video

[CRCinAU]

I have a need to use several pis with screens to display multicast video in sync across a network.

From my current experiments, it seems like the display of video can vary in position by up to around 15 seconds. It seems to be related to buffering and when in the video stream that omxplayer is started.

This makes it almost impossible to have several different Pi's showing the same segment of video at the same time.

Is there a way to sync this - via either supporting VLCs network playback sync, or via a different method to achieve synced playback of a multicast video?