EditDV Application Note #13

Controlling Processing Order

In EditDV, transitions on a track always render before filters. This is useful when adding titles to a sequence with transitions, for example, so that the titles remain unaffected by the transitions in the video media.

However, in other cases, this is undesirable. For example, if the Mirror filter is applied to one clip that is dissolved into another unfiltered clip, you will see the clip mirrored until the beginning of the transition, where the transitioned frames are then mirrored instead of just the filtered clip.

You can avoid this by using a feature called a Òhanging transitionÓ, which will force the filters to be processed before the transition. The hanging transition transitions one clip to a clip on a different track. The transition will behave normally, and the trim monitor may be used normally. But hanging transitions are processed after all filters are processed on both tracks.

An Example

The following transition will not be rendered correctly. The incoming clipÕs frames will be inapproriately mirrored until the cut point, where the filter ends. The outgoing clip will stop being filtered at the cut point.

This is the same edit, with the blue disclosure triangle turned down:

The filter shown above will process the frames used for the incoming clip with the Mirror filter, up to the cut point. Furthermore, the incoming clipÕs frames used to process the transition are not mirrored after the cut point, because the filter ends at the cut point.

To cause all of the incoming clipÕs frames to be mirrored without affecting the frames in the outgoing clip, use a hagning transition.

To set up a hanging transition:

1. Drag the incoming clip to the next lower video track.

2. Reapply the transition to the incoming clip.

This is how the same edit looks with the blue disclosure triangle turned down on the incoming clipÕs track:

The hanging dissolve will not refer to media beyond the cut point on a different track, so if this edit were rendered now, the outgoing clip would suddenly disappear midway through the transition. Therefore, the outgoing clip must be extended to acommodate the transition.

The best way to do this is by using the Trim monitor.

3. Ripple edit the outgoing clip to the end of the transition.

Enter Trim mode and drag the outgoing clip (the left side of the monitor) to the right until the length of the clip matches the end of the Dissolve in the Sequencer.

The edit should now look like this:

Note that the Mirror filter ends at the cut point. Its length should also be increased to match the length of the outgoing clip.

4. Drag the filterÕs endpoint to match that of the transition:

Now the edit is complete. Every visible frame in the outgoing clip will be mirrored. None of the incoming clip will be mirrored. The hanging transition will dissolve between the two as expected.

Trimming a Hanging Transition

Trimming a hanging transition is almost as simple as trimming a normal transition. Simply enter trim mode, and shift-click the cut points of the two clips:

Then, trim the clips normally.



Author: Mike Jennings
Applies to Version(s): All

Last Updated: 11/21/98

 

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