Transitions
The join's named moves between two scenes, what each draws, its settings and eases, and what the element moves ask of a scene.
A hand-off is the moment one scene becomes the next. The join draws it, not the builders: each move runs frame by frame in headless Chrome from both scenes' real frames, and the video is each scene's own frames with the drawn hand-offs between them. A storyboard scene names its hand-off in out, and the last scene's is ignored. With no out, it's a cut.
A name is a quick way to say a hand-off and get it drawn, not the limit of what a hand-off can be. Tune a move with ease, dir, at, color, and params. When no move fits, build the hand-off inside the two scenes (carry an element out, land on the frame the next scene opens with) and cut. The blocks page plays every move here but cut and match.
The fields
{ "kind": "roaming-iris", "dur": 0.5, "ease": "in-out", "at": [0.5, 0.42], "params": { "radius": 0.2 }, "notes": "opens on the card" }| Field | Type | Notes |
|---|---|---|
kind | a move | the tables below |
dur | seconds | the overlap; default 0. All but cut and match take at least 0.1 s |
ease | linear, in, out, in-out, snap, expo | how its progress runs; each move has its own default. snap overshoots and settles, expo rushes in |
dir | left, right, up, down | the way a directed move travels |
el | a data-el | required by the element moves |
at | [x, y] | a point in the frame, each a share from the top left; default the centre |
color | #rrggbb or a palette token | for dip and glow-bloom; the join reads a token from the style |
params | object | a move's own settings |
notes | string | how the two scenes meet; default "" |
An overlap plays the end of one scene under the start of the next, so a video runs shorter than its scenes laid end to end, by whole frames. An overlap takes at most half the shorter scene, so no hand-off swallows one.
Soft moves
kind | Draws | Default ease | params | Usual dur |
|---|---|---|---|---|
cut | a hard cut | 0 | ||
dissolve | one picture through the other | in-out | 0.3–0.6 | |
dip | through color, white by default | in-out | 0.15–0.4 | |
blur-through | the picture blurs out and the next blurs in | in-out | 0.3–0.5 | |
glow-bloom | light blooms at at as it dissolves through, in color, or the next scene's colour there | in-out | 0.3–0.5 |
Pushes and reveals
kind | Draws | Default ease | Default dir | params | Usual dur |
|---|---|---|---|---|---|
wipe | a soft edge travels toward dir | in-out | left | 0.3–0.5 | |
snap-push | the next scene shoves the last off, hard edge, small overshoot | snap | up | 0.12–0.25 | |
deck-rise | the next scene rises as a card; the last sinks back, dims, and peeks above | out | up | 0.2–0.35 | |
hinge-swing | the next scene swings in like a door hinged on one edge | out | left | 0.2–0.35 | |
thread-ribbon | a thin wavy line draws across, then widens into a ribbon of the next scene | in-out | right | amp (0.05), waves (1.5) | 0.4–0.6 |
glare-sweep | a diagonal band of light sweeps across, the next scene behind it | out | angle (30), width (0.12) | 0.12–0.3 | |
flood | the next scene opens out from the centre | out | 0.3–0.6 | ||
roaming-iris | a round window onto the next scene travels from params.from to at and opens | in-out | from, radius (0.16) | 0.4–0.6 |
Depth and force
kind | Draws | Default ease | params | Usual dur |
|---|---|---|---|---|
zoom-through | the camera pushes into the last frame until the next emerges | in | 0.3–0.6 | |
point-arrival | the next scene flies in from a speck at at until it fills the frame | expo | 0.35–0.6 | |
plane-tilt | the frame tilts back like a card, one white frame, the next swings up flat | in-out | tilt (78) | 0.4–0.6 |
tile-shatter | the frame breaks into tiles that spin and fall from at, the next scene under them | linear | tiles (14) | 0.4–0.7 |
signal-tear | torn bands and slice shifts glitch one picture into the next | linear | 0.3–0.5 | |
ripple-warp | a liquid ripple spreads from at and carries the next scene in | out | 0.3–0.5 |
params.from defaults to just below the frame, straight under at. Both may sit off the frame.
Element moves
These read a real element's box from the scene's .boxes.json, so they need el, the data-el of something the scene draws. A move that overlaps fails the join when its element is missing, and the error names it.
kind | Draws | Default ease | params | Usual dur |
|---|---|---|---|---|
match | a cut, or a short dissolve, on a shared element in the same box both sides | in-out | 0 or more | |
held-object | the element holds still while the world behind it is swapped | in-out | 0.3–0.5 | |
mosaic-dive | the camera dives into one tile of a grid, which becomes the next scene | in | reverse | 0.35–0.7 |
glyph-swallow | a letter or mark turns and grows past the frame; its fill is the next scene | in | turn (15) | 0.6–1.1 |
lens-portal | a lens or ring shows the next scene inside it, then the camera rushes through | in-out | 0.4–0.6 |
Each asks something of the two scenes:
match,held-object: the last scene ends with the element in the box the storyboard gives, and the next starts it there, still. The join reports one that moves more than 8 px across the cut or is missing on one side. After a held object, the next scene owns its exit.mosaic-dive: the last scene ends on the grid with the tileel, and the next opens on what that tile showed. Withreverse, the next scene's tileelis what the camera pulls back out of: open on the tile's content and land on the grid.glyph-swallow: end on the mark, still, on a plain ground. The next scene opens on a field of the mark's colour.lens-portal: end with the lens or ring still, roughly square in its box.
On the command line
rapid join --transitions and rapid video-sheet --transitions take one per hand-off, kind[:dur[:dir or el]]:
rapid join a.mp4 b.mp4 c.mp4 d.mp4 --out picture.mp4 --transitions "snap-push:0.15:up,cut,glyph-swallow:0.9:mark"A move that carries an ease, a point, a colour, or settings goes as the list in JSON:
rapid join a.mp4 b.mp4 --out picture.mp4 --style swiss --transitions '[{"kind":"dip","dur":0.2,"color":"accent"}]'Choosing
- Plan them as pairs. The last frame of one scene and the first of the next are designed together. Hold a frame worth seeing through the overlap.
- Match the scale of the move to the moment. A quick snap (
snap-push,glare-sweep,dip) between two fast scenes, a big move (glyph-swallow,lens-portal,mosaic-dive) where the story turns. - Vary them. One move three times running is a habit, not a hand-off.
- Count the overlap. In a video cut to a track, the beat a hand-off is held to is where the next scene starts: the overlap's first frame.