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Enhancements to Effects

A new effect has been added to QuickTime 5 –– the Travelling Matte. The Travelling Matte, a common type of effect used in video and movie work, is a matte shot where the matte changes from frame to frame to conform to the action in a scene.

Notably, this is the first three source effect introduced in QuickTime. The effect behaves, in general, similar to a gradient wipe, which was already available to developers in previous versions of QuickTime. In both the travelling matte and gradient wipe cases, there is a “matte” which controls whether source A, or source B, or a blend between the two appears. The exception is that in the gradient wipe case this is a still image, where in the travelling matte case it is another video track. That’s the “travelling” part of it. Developers who are building video applications should find this effect useful because it is an effect that can have more than two inputs.

The parameters for travelling mattes support a normal matte, as well as a matte that’s inverted. Typically, you’d have, for example, black as source A and white as source B, so you might have pulled the matte –– “pulling the matte” is a technical term, i.e., how you get the matte from the source material –– with a piece of software that got you the inverse. The parameters support inverted, and treating the matte as a moving gradient.

QuickTime 5 also includes changes to the gradient wipe effect. These changes are, essentially, to support the parameter softness, so that the effect gives you a smoother transition from one source to the other. This means that it will be more useful to developers.

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