QuickTime 4 Reference

One-Source Effects (Filters)

Effects that require a source, such as a blur filter, steal the output of a video track by using an input map. The video track's output is sent to the effects track, and the effect component acts as a special kind of codec to convert the video into the desired effect.

If you want to apply a filter effect to a whole video track, create an effects track with the same offset and duration as the source track. The input map does the rest.

If you want to apply a filter effect to part of a video track, make a new track that references the desired part of the video, then create an effects track with the same offset and duration as this new track. The new track is the source for the effect. You normally want to put the effects track in front of the original track.

Figure 2 An single-source effect overlaying part of a video track