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Re: Creating Video Software
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Re: Creating Video Software


  • Subject: Re: Creating Video Software
  • From: "Douglas A. Welton" <email@hidden>
  • Date: Tue, 19 Aug 2003 08:22:13 -0400

In regards to using the QuickTime API, check out sprites.

A sprite is an animated image that is managed by QuickTime. A sprite is
defined once and is then animated by commands that change its position or
appearance.

later,

douglas

on 8/19/03 1:31 AM, email@hidden at email@hidden wrote:

> I'm about to start development on a new special effects program. It's
> a very basic program that basically takes images with alpha channels
> and composites them over a video fame. So, it might take a picture of
> a lightsaber and composite it on a video frame using alpha channels in
> the lightsaber image. The user will need to be able to drag the image
> around on the screen, resize it, etc. The software will create the
> effects on a frame by frame basis.
>
> I'm not sure how to approach creating this software. I've looked into a
> couple different options:
>
> 1) Video frame to NSImage using Quicktime API: One way to create the
> program would be to convert every frame of the video to an NSImage when
> the movie was loaded. Then, I could just use NSComposite to composite
> the effects image over the frame. To handle scrolling through the
> frames, the software could just update the NSImageView with the correct
> image for the frame selected. When the user is ready to export it just
> creates a movie file by combining all the different NSImages using the
> quicktime API. This route seems to take a lot of overhead in terms of
> memory, especially if its a large movie.
>
> 2) Use quicktime API: I haven't looked into using the quicktime API
> that extensively yet. I suppose there are functions that would let me
> composite the image over a video frame without first converting the
> video frame to an NSImage. I'm not sure how I would display this on
> the screen through, especially since the user needs to be able to drag
> the image around over the video frame.
>
> 3) OpenGL: I'm not sure if this would even work, but what about openGL?
> Perhaps I could use some openGL functions to composite the images over
> the video? That might even allow me to composite 3D objects over the
> video frame?
>
> 4) QuickDraw: Maybe I could use the older carbon QuickDraw functions to
> do the compositing. QuickDraw seems rather old...
>
> Well, no matter which route I chose, I still need some way of keeping
> track of the location of every image on ever frame. I suppose I could
> just create a NSMutableDictionary with the position of each corner of
> the image for each frame?
>
> Any suggestions on which route to take and how to keep track of the
> image coordinates would be VERY helpful. Thanks!
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References: 
 >Creating Video Software (From: email@hidden)

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