Intro and outro

Text 
Intro@slide-up,ease-out,700ms "Musicbox" "Chord progressions, sketched and heard"
Outro@fade,800ms "Recorded with reel" "brew install --cask mpdreamz/tap/reel"
Set IntroBackground //demos/backgrounds/intro-16x10.jpg
Set OutroBackground //demos/backgrounds/outro-16x10.jpg
Intro "<title>" ["<subtitle>"] [duration] A title card before the demo: 3 s, or a background video's own length.
Outro "<title>" ["<subtitle>"] [duration] One after it.
Intro [duration], Outro [duration] No title: your own video on its own, such as a designed sting or a logo animation.
Set IntroBackground <bg>, Set OutroBackground <bg> #rrggbb, an image (.png, .jpg, .heic) or a video (.mov, .mp4). A video's sound plays with it. Near-black unless set.

Titles are centred, white with a soft shadow, sized from the video. A background fills the frame, cropped evenly.

An intro or an outro can be any video you made: a logo animation, a sting, a clip from somewhere else. Set it as the background and leave out the title, and it plays as it is, with its sound:

Text 
Set IntroBackground //brand/intro.mp4
Set OutroBackground //brand/outro.mp4
Intro@crossfade
Outro@fade

reel's own demos open and close this way, on the stings in its brand kit. With a condition each cut can have its own: Set IntroBackground social ? //brand/intro-9x16.mp4 : //brand/intro-16x9.mp4.

Intro@<kind>,<easing>,<duration> says how the intro moves into the demo; on an outro, how the demo moves into it.

Kind
crossfade The default, over 600 ms.
fade Through black, half on either side of the cut.
slide-left, slide-right, slide-up, slide-down Pushes one out as the other comes in.
zoom Grows out of, or into, the demo.
wipe-left, wipe-right, wipe-up, wipe-down Reveals the demo beneath.
cut No transition.

Any easing works: Intro@slide-left,ease-out,800ms. Titles move, or are wiped, with their card, and the sound crosses the same way.

Intros and outros are render-only: a changed title, background or transition needs no new recording.