Managing and Working with Gap Batch FX

A Gap Batch FX (or Gap BFX) consists of a Batch FX segment created in a timeline gap which uses as input the top media of the layers below that timeline gap. Inside Batch FX, that input is called the Back clip.

To add an effect without losing your timeline edits:

Select a gap over the segment to which to want to add an effect.
Alternatively, click Layer+ to create a new top layer in the Timeline.
Click Pre.
Batch FX opens, with the Back Clip as the input.
Add nodes to create your process tree.
Exit Batch FX.
A BFX is now on the selected gap.

The example above uses the top layer for the placement of the BFX, but a Gap BFX does not have to reside there, it can in any gap where you need it to be. You can even pile Gap BFX upon Gap BFX.

At first, Clip 1 is used as the Back clip. When Clip 2 becomes the top clip of the timeline, it becomes the Back clip.

More About Gap BFX

The input available inside a Gap BFX is the Back clip. That means that if you have three layers composited together, and you add a Gap BFX on top of them, the image available through the Back clip is only the output of the third layer. In other words, you can use Gap BFX instead of Post if your goal is to apply an effect after the vertical composition. But you cannot use the Gap BFX workflow to recreate the Post BFX workflow: you cannot split the layers and then use BFX to composite them together.

You do not have access to individual layers inside a Gap BFX.

The Gap BFX does adjust to the destination resolution.

Copying Gap BFX Between Timeline Segments

Copy a BFX from a segment or from a gap.

To copy a BFX between timeline segments or gaps:

Press Ctrl and drag the BFX indicator to another element, to a selection of elements, or a gap on the timeline.
If you copy the Gap BFX to a timeline segment (as opposed to a gap), it becomes a Soft Effect BFX.

TipYou can select the gap (and the applied BFX) instead of only the BFX, and move that gap somewhere else on the timeline. F+drag to copy the gap instead of moving it.

Editing Gap BFX on the Timeline

You can perform edits on a Gap BFX as it is treated like any other timeline segment. Operations like:

Trim
Slip
Move
Add transitions
Copy

NoteYou can trim a Gap BFX to infinity.

The BF marker that appears on a Gap BFX in the timeline gives the first frame's ranking, with BF:1 indicating the original frame.

Things that cannot be done with a Gap Batch FX:

You cannot enter a Post Batch FX when a gap is selected.
You cannot create multiple levels of Batch FX on a gap.

Recognizing the Types of BFX

BFX Icon:	Type of BFX:
	Regular Pre-BFX
	Gap BFX
	Pre-BFX that uses a Back Clip BFX node in the BFX schematic.

About the Back Clip Node In Batch FX

The Back clip node is available in the I/O bin of Batch FX. The Back Clip node does not contain any media; instead, it offers a link to the superior Timeline level, giving access to the topmost media located below the BFX segment you are currently working on.

The Back clip node enables you to create composites and effects in Batch FX without the need to physically bring all the media inside Batch FX, reducing the dependency on the use of Post Batch FX.

On the other hand, the Back Clip node is just a link to media: you cannot access Basic, Resize, RGB LUT, Timeline, Audio. Only the following options are available.

Head Media button: Set what media is available before the In Point of the Gap BFX. Select Timeline Level to have the Back Clip read the head media from the segments preceding (and below) the Gap BFX.
Tail Media button: Set what media is available after the Out Point of the Gap BFX. Select Timeline Level to have the Back Clip read the tail media from the segments following (and below) the Gap BFX.