Command · Add Transition

transition.add

Adds a transition at a clip's head or tail: on the cut when the neighbouring clip meets that edge, otherwise inside the clip (a fade from/to black).

• v1
• Capability EditSequence
• Tool transition_add

Request

{
  "command": "transition.add",
  "params": {
    "clip": 42,
    "duration": "00:00:00:12",
    "edge": "tail"
  }
}

Parameters

alignment`center` | `startAtCut` | `endAtCut` | `custom`

Where the transition sits on a cut between two clips: centered (default), starting at the cut (the outgoing clip plays on), ending at it, or custom: the cut lies "offset" into it (by default where it is now). Stored on the transition: a new duration keeps it. Ignored for a one-sided transition at a clip end with no neighbour.

clipinteger | object (1..)Required

The clip. A clip id, or {"track", "time"} for the clip there.

durationinteger | string

Transition length. Default 1 second. Timecode in the sequence's rate ("00:01:02:03") or ticks.

edge`head` | `tail`Required

Which edge: "head" (the clip's In point) or "tail" (its Out point).

effect`crossDissolve` | `dipToBlack` | `dipToWhite` | `wipe` | `constantPower` | `constantGain`

The transition (effect.list).

fit`exact` | `availableHandles`

When the media lacks frames beyond the cut: "exact" fails with how much there is, "availableHandles" shortens the transition to fit (default).

offsetinteger | string

With alignment "custom": how much of the transition lies before the cut. Timecode in the sequence's rate ("00:01:02:03") or ticks.

paramsobject

Constant parameters, e.g. a wipe's {"angle": 90}.

sequenceinteger (1..)

Sequence id; only needed when the project has several.

Discussion

Run it with wabcut-cli cmd <project> --json, from an MCP client as transition_add, or from an extension. See Edit commands for requests, references and results.