QtAV/doc/MultiplePlayersSynchronization.md

Hypothesis

The players' playing states are not changed when syncing, e.g. speed, play or pause state.

KEY

Sending and Recieving the sync requests takes time. The delay must be computed

Solution

Players in 1 Process

Use AVClock. It's easy.

Players in Network

Pass 2 value. One is aboslute time when sending the sync request. Another is the play time of the video.
This method also works for players in 1 process