How to play multiple videos in sync over multiple monitors using directshow?

Question

Hi all. I´ve successfully managed to play up to 8 videos in sync using a single video window with multiple streams using the directshowlib for c#. The problem is the video window plays only on a single screen - when I try to have it span over many screens it does not work. The app window spans correctly, but the video plays only on one screen. Any ideas?

Thanks a lot in advance.

Answer 1

I assume that you're using the VMR with multiple input pins. The VMR is going to render to a single surface, which needs to be on a single display. You should be able to render your streams to multiple VMRs, with each VMR placed on a separate display within your maximised window.

It sounds as though you have all the streams in a single graph. You can separate them into different graphs, with each graph having one source and one renderer. Starting the graphs in sync means using IMediaFilter::Run instead of IMediaControl::Run:

• Pick one graph as the master.
• Make sure the master has a clock. This is normally done when going active, but you can force it to happen earlier by calling SetDefaultSyncSource on the graph.
• Query the graphs for IMediaFilter, get the clock from the master graph using GetSyncSource and pass it to the other graphs using SetSyncSource.
• Pause all the graphs.
• Wait until GetState returns S_OK (the pause is complete).
• Get the time from the graph and add 10ms or so.
• Call IMediaFilter::Run on all graphs, passing this time (now + 10ms) as the parameter.