Synchronizing Video-Start



  • Hello,

    I have a question/problem :

    I want to start three seperate Movie-Files simultaniously, with them starting to play at the excact same time.

    When i trigger the videos, each one has an individual delay ( 0,1-1,0s) until it starts playing. When one "loads" very fast, but the other one takes a second to start, 

    you can imagine that there is a offset between the two. This seems to be random. Sometimes the offset is not notiable, sometimes its almost a second.

    I tried using the classic movie preload actor to preload the big video files, but that just keeps crashing isadora.

    Using the position pointer of one movie for the playback position of the other movie, it results in stuttering playback.

    Has anyone any idea?

    Thank you very much in advance!

    PS: Im working on a powerful MacPro with 64gb RAM and Intel Xeon Processor.


  • Tech Staff

    @mo

    What OS X version are you using?
    What version of Isadora are you using?
    What is the codec and resolution of your movies?
    Are the movies played from an SSD drive?

    Best Michel



  • Is there a reason you cannot make one movie out off all of them with larger dimensions and spread it across your projectors? This is the best way to guarantee sync. Otherwise in my experience OSX lags a bit at this, the same structure on windows with DS playback gives near jam sync by starting movies from a single signal.



  • To sync multiple video's I almost always use the position:

    All the sound on one video. (sometimes just a black video) = master

    Than i connect the position output of the "master" to all other video's (on interactive & with speed 0 otherwise you get stuttering). 


  • Tech Staff

    @mo
    When you say 'trigger' the movies, what exactly are you doing to start playback?
    If turning 'on' the movie player, the startup of the player may have delay.
    If changing the movie ID #, there will be load delay.
    However, you may find less/no delay if you have the movie ID set, the Player set to ON, and the speed set to 0, then input a 1 for the speed to all players.
    Depending on drive speed (SSD is a must), and codec (I prefer HAP), you could get a rather in sync startup.
    Using HAP as the codec, should also allow the option of using a Master to control others via the Position output a viable option.
    For Perfect Sync, @Fred has outlined the most reliable method.



  • On my experience to have a sync frame by frame the only solution is to have a multiple video an then crop it. Other solutions can introduce some jitter on frame decoding. 



  • Dear All,

    Thank you so much for all your responses! 

    I don't have the time right now, to answer all of your great feedback.

    I tried using the position method , where the position of one "master" movie player controls the position of the rest, but that resulted in jittery playback.

    I will try out the speed 0/1 method next, thank you for that idea!

    best regards

    mo


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