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How do I create a smooth transition when opening videos or transitioning between separate videos?

April 1, 2009 | 4:28 pm

I am running three videos to three different projectors and I am having trouble creating a nice transition when I open video files. In my current patch there is a noticeable "jumpiness" when I open the video files.

I would also appreciate any advice on smoothly transitioning between separate video files.

A simple fade to black and a fade from black or something similar would be desirable. I am worried that this "jumpiness" I am currently experiencing when I open/close videos will also be apparent when I try to transition to new video files.

Moreover, I would appreciate any help on removing the "can’t make context" warning messages I get in the Max window whenever I stop the video stream in my patch. I have no idea what is causing this to occur.

Thanks,
Ben


April 1, 2009 | 4:49 pm

as long as you only "read" your movies at load time, transitioning is just a matter of using jit.xfade (or jit.op or whatever) and sending "start" and "stop" to the qt.movie objects.

if you try and "read" right before a transition, you will get a stutter.

also [> 1] -> [sel 2] will never do anything. logic operators only output 1 or 0 (ie true/false).


April 3, 2009 | 2:39 am

Thanks for your help so far.

The patch I am writing will potentially need to load 12+ different videos at runtime and then it needs to be able to start and stop them at various points in time during the performance.

Is there anyway I can load them all at the beginning and then open specific videos at certain points in time during the performance?

I assumed I could do it by naming jit.qt.movie but it doesnt seem to work that way.


April 3, 2009 | 12:50 pm

The question is how many jit.qt.movie you want to use (you can load only one movie per jit.qt.movie).
You could use 2 (to allow transitions), and load the movies when you need them. You could use the read confirmation send out the dumpout output of jit.qt.movie to begin the transition only when the movie is indeed finished loading.
Or you could use 12 jit.qt.movie, one for each movie, and use a kind of mixer between all of them. In this case, you could look at [poly~] (what if suddenly you want 15 videos instead of 12?). You would also look into doing the mixing and display in OpenGL world.
But the first method could work just fine if you want a good quality, but not the best responsiveness.
Jean-François.


April 3, 2009 | 9:25 pm

Ben Miller wrote on Wed, 01 April 2009 11:28I am running three videos to three different projectors and I am having trouble creating a nice transition when I open video files. In my current patch there is a noticeable "jumpiness" when I open the video files.

I would also appreciate any advice on smoothly transitioning between separate video files.

A simple fade to black and a fade from black or something similar would be desirable. I am worried that this "jumpiness" I am currently experiencing when I open/close videos will also be apparent when I try to transition to new video files.

If it’s possible, you could combine all your movies into one large one and load that, then jump around using frame $1 commands. This works more smoothly than loading multiple ones. Also the file format and compression can have an effect (for example when I play .avi it really bogs down). I use .mov and an mpeg-4 compression, set at about 80% quality (from Sony Vegas). These files look fine, are quite small, and play back nicely.

Here’s a couple examples of fading, including a "video reverb" using jit.xfade with itself that I saw on the forum awhile back. Easy to implement and has a cool effect. You can also set the speedlim value of the remixing frames to a BPM of your choice. In the patch it’s initially set very low (50 ms) so the effect is smooth, but try 500 ms and you’ll see a rhythmic pulse of the fading frames. Tying this to an audio beat can be effective.

So when you jump between sections of a movie, or are loading new ones, you could trigger a fade out/in, or maybe use the "reverb" more strongly for a few seconds.

I don’t know about the "can’t make context" errors.

– Pasted Max Patch, click to expand. –

April 12, 2009 | 9:25 pm

Thank you all for your replies. I have "finished" the general structure of the patch and almost everything seems to work quite well. I am attempting to load all of the sound and movie files at the beginning of the patch so that the max patch can perform as efficiently as possible throughout the actual theatrical performance.

However, sometimes a video feed will freeze. This happens somewhat randomly and it doesnt have anything to do with the source files themselves. A video feed will just freeze on a particular frame while the audio continues to play.

I am loading around 13 gb of separate .mov files exporting them from Premiere as .mov using a DV/DVCPro-NTSC codec (I tried to use mpeg4 and the quality of the movies was pretty terrible).

I assume my problem is related to performance issues but since it is somewhat spotty, I am unsure.

I would appreciate it if someone could take a look at the patch and let me know if there is a better way to load files or if they see anything amiss.

Cheers,
Ben


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