crossfade

Overlap two Videos or Audio values with a crossfade transition.

Call shape

crossfade<T: Video | Audio>(before: T, after: T, duration?: Duration) -> T

This is call-shape notation for lookup, not ClipAsm declaration syntax.

Graph inputs

Parameters and defaults

Result and stack behavior

Outputs: T.

All T inputs and outputs use one homogeneous type: Video or Audio. Use an explicit <Video> or <Audio> argument when the accessible stack makes inference ambiguous.

Default stack access is owned. See stack binding for ownership and visibility rules.

Timeline and markers

The program overlaps the end of before with the start of after. It exposes before, overlap, and after regions.

Example

clipasm 1

config {
    video {
        fps = 30
    }
}

image("assets/before.png", 2s)
image("assets/after.png", 2s)
crossfade

Expected validation result: Video with exactly 105 project frames at the example’s explicit fps = 30.

The reference checks parse and compile this exact example. Compilation does not inspect the named media files.

Behavior

• For Video, duration becomes the smallest whole project-frame count that covers the authored duration; for Audio, it becomes the smallest whole project-sample count.
• Video pictures blend in display-linear BT.709 RGB, while standalone and attached Audio use equal-power fade curves.
• The output exposes before, overlap, and after timeline regions.

Requirements

• before and after must have the same Video or Audio type.
• duration must cover at least one native frame or sample and cannot exceed either input.

Common diagnostics

These are the diagnostics most specific to this program.

• E_INVALID_CROSSFADE_DURATION — Invalid crossfade duration
• E_CROSSFADE_AUDIO_DURATION — Invalid crossfade audio duration

See also

• flash_cut
• Statements and calls
• Stack binding