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Local Video in Sesi

Use video() to create a video from an ordered list of image frames or to

transcode an existing media file. This is the no-AI form:

video(input, output, options?) -> string

It uses the local ffmpeg command-line tool, requires FFmpeg on your PATH,

and is unavailable in safe mode. The function returns the output path.

---

Image Frames to Video

Pass frame paths in their intended display order. The output directory is

created when needed.

let frames = [
  "frames/001.png",
  "frames/002.png",
  "frames/003.png"
]

let output = video(frames, "build/preview.mp4", {
  fps: 24,
  width: 1280,
  height: 720,
  codec: "libx264",
  crf: 23,
  preset: "medium"
})

show "Saved" output

Transcode a Video

Pass an existing media-file path as the input to convert it to another format

or apply output settings.

let output = video("recording.mov", "build/recording.mp4", {
  fps: 30,
  width: 1920,
  codec: "libx264",
  crf: 20
})

show "Saved" output

Add or Remove Audio

Use audio to attach a local audio file. Sesi maps the first video stream and

the supplied audio stream, then stops when the shorter stream ends. Use mute

to omit all audio instead.

let output = video("source.mp4", "build/with-music.mp4", {
  audio: "music.wav",
  codec: "libx264",
  crf: 21
})

let silent = video("source.mp4", "build/silent.mp4", {mute: true})

Options

Key	Type	Default	Description
`fps`	`number`	`30`	Output frame rate, from `1` to `240`.
`width`	`number`	source width	Output width, up to `8192`. If only one dimension is set, the other is calculated and kept even.
`height`	`number`	source height	Output height, up to `8192`. If only one dimension is set, the other is calculated and kept even.
`codec`	`string`	`libx264` for MP4; `libvpx-vp9` for WebM	FFmpeg video encoder.
`crf`	`number`	`23`	Encoder quality value from `0` to `63`; lower generally means higher quality and larger files.
`pixel_format`	`string`	`yuv420p`	Output pixel format.
`preset`	`string \`	false	`medium`	x264/x265 encoder speed preset; set to `false` to omit it.
`audio`	`string`	none	Local audio-file path to add to the output.
`mute`	`bool`	`false`	Remove audio; takes precedence over `audio`.
`overwrite`	`bool`	`true`	Set to `false` to fail instead of overwriting an existing output file.
`timeout`	`number`	none	Maximum FFmpeg runtime in milliseconds, from `1` to `86400000`.

.mp4, .m4v, and .mov outputs are prepared for progressive playback.

For WebM, use a .webm output path; Sesi selects libvpx-vp9 unless you set a

different codec.

Check FFmpeg

ffmpeg() accepts a structured argument array and returns process details. It

can be used to check whether FFmpeg is available before rendering:

let installed = !(["-version"] | ffmpeg | is_null)

if installed {
  show "FFmpeg is ready."
} else {
  show "Install FFmpeg and ensure it is available on PATH."
}