Forums > MaxMSP

Changing Video Coordinates


zashort
April 10, 2012 | 5:41 am

Okay, Im not sure if this is in the correct place so please correct me if I am wrong as I am knew to this. I do have some Max MSP knowledge but I am stumped.

I am looking to take the silhouette of a person, the video of a silhouette anyway and move the movie through a space. I can’t seem to figure out a way to move the video based on an x coordinate. I managed to do so with a picture but I need to control the video speed based on the change in x. and change the x coordinates of the video based on the x coordinate I give to the patch. Let me know if you need any more information as this is somewhat hard to explain. Any and all help would be amazing! Thanks in advance!


lembert.dome
April 10, 2012 | 5:58 am

I am confused by your request. You seem to be asking two things:

1. How to move part of a video (a silouette) around the window
2. How to also change the rate of that video based on its x-coordinate.

First, the easiest way to move videos about the window is to use jit.gl.videoplane.

Second, the x-position (in this case a gl coordinate, not a pixel-position) can simply be scaled and fed into the rate of the jit.qt.movie, or you can be controling which frame is being shown using the frame $1 command to the jit.qt.movie.


zashort
April 10, 2012 | 6:17 am

Thanks for the quick response!

Basically I have a looping video. The silhouette which is suposed to represent a shadow. In the pictures attached I managed to move just a still image through the space attached to the x coordinate. The x coordinate will be associated with a person moving through a given space and I am attaching my own shadow to their feet. So when the person stops. or the X coordinate stops I want the video to stop. But when the person is moving I want the video to be playing or looping.

1. How to move part of a video (a silhouette) around the window

somewhat. It is only the silhouette in the movie. so If I can find a way to move the entire movie move that would work.

2. How to also change the rate of that video based on its x-coordinate.

Yes the faster the x-coordinate is changing the faster the movie is playing. And if the x coordinate is not moving or stopped the video will loop slowly or stop.

Thanks again! I will look into jit.gl.videoplane and see if this helps!

[attachment=190657,3679] [attachment=190657,3680]

Attachments:
  1. ScreenShot20120409at11.07.38PM.png

zashort
April 10, 2012 | 7:09 am

Ok the Jit.gl.videoplane seems to be working perfectly. The only question I still have is if there is any way that I can make the change in x change the framerate on a video. Basically if the x coordinate is 15 in one frame and 13 in the next compared to 15 in one fram and 8 in the next. The one with the change of 7 will make the movie loop faster than the change of 2 where it should go slower. Thanks again!


lembert.dome
April 10, 2012 | 4:10 pm

You want to scale your rate of change in X to your video’s playback rate. If you are dealing with isolated changes in X, this patcher will work for you:

– Pasted Max Patch, click to expand. –

If, however, you have a stream of X values and you need to calculate their rate of change, you need a different strategy.


zashort
April 10, 2012 | 10:54 pm

Ya I will be streaming the coordinates in from a program pulling the x coordinates from a kinect.


lembert.dome
April 11, 2012 | 12:47 am

Aha. Here are two suggestions:

For the silouette, take a look at the last patch on this page:
http://cycling74.com/forums/topic.php?id=38963
Use [pak position 0. 0. 0.] to position the mesh in the window.

For the speed of the video, try a variation of this:

– Pasted Max Patch, click to expand. –
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