Mark Coniglio
TroikaTronix
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May 17, 2007, 4:10 AM
Post #1 of 17
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Syncing Videos Among Multiple Computers
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Hi All,
I had a question about synchronizing video among multiple computers, which comes up fairly often. So I thought I'd post the answer here.
Best,
Mark
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There is no functionality in the current version of Isadora that provides tight, real-time synchronization for movies that play over a long period of time (i.e., hours.)
That being said, you can often achieve good sync by doing the following
1) Set up a Movie Player and Projector on each computer. Set the 'visible' input to 'off' in the Movie Player. Also, click on the word 'visible' to open the Inspector; make sure the 'Init' checkbox is ticked.
2) In the same scene, add a 'Video Preload' actor with the 'video low' and 'video high' inputs set to the same movie that will be played by the Movie Player. Connect its trigger input to an Enter Scene Trigger actor, which can be found in Group 7. Click the 'trigger' input on the Video Preload actor to preload the movies now.
3) Finally, on the "slave" computers, add a Listener actor. Set the 'type' input to 'integer' and the the channel to 100. Take the output of this actor and link it to the 'visible' input of the Movie Player.
4) On the "master" computer, add a Net Broadcaster. Set it's channel to 100. Also, add a Trigger Value actor. Set it's value input to "1". Link it's output to the Net Broadcaster input. If the master computer is playing a video too, link the Trigger Value actor's output the 'visible' input on the Movie Player in this scene.
5) Now, click the 'trigger' input of the Trigger Value on the master computer. This sends a '1' to the Listener actors on all the slave computers, which in turn, sets the 'visible' input to "on", and all the movies begin to play.
However, you should not loop the movies and expect them to stay in sync. Apple Computer has indicated to me that the code that performs the looping function is such that there will be unpredictable amounts of delay in looping from the beginning of the movie to the end. If you need to loop material, the sequence is this:
1) Preload the Movies
2) Send message to all using Net Broadcaster to start playing
3) Use "loop end' trigger from one machine to repeat starting from Step 1
This of course assumes that all movies are of the same length. If not, you'd have to use the 'loop end' trigger from the Movie Player playing the longest movie.
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Mark Coniglio / TroikaTronix
Creator of Isadora
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