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Supply root inputs and parameters

A root source program can ask its caller for Video or Audio inputs and scalar parameters. This guide uses examples/root-bindings.clipasm, which declares one Video, one time range, and one repeat count. You will bind all three and render a two-second MP4.

Before you start

Use a ClipAsm source checkout. Run the commands from its repository root. The committed examples/assets/gentle-motion.mkv supplies the Video. Rendering also requires FFmpeg and FFprobe.

1. Read the declarations

input video: Video
param range: TimeRange
param count: Integer

trim($video, $range)
repeat($count)

None of the declarations has a default. Every compiling command must supply all three values.

2. Bind every required value

$ clipasm validate examples/root-bindings.clipasm
> --video-input video=examples/assets/gentle-motion.mkv
> --arg range=500ms..1500ms
> --arg count=2
valid: 4 semantic value(s), 48 frame(s)

Use:

  • --video-input NAME=PATH for a declared Video
  • --audio-input NAME=PATH for a declared Audio
  • --arg NAME=VALUE for a scalar parameter

Names are case-sensitive and must match the source declarations. Repeat an option when a program declares several values of that kind.

If a binding is missing or misspelled, note the reported diagnostic code. Run clipasm explain <CODE>. Then correct the command and validate again.

3. Render to an explicit output

The example has no configured output, so provide one:

clipasm render examples/root-bindings.clipasm \
  --video-input video=examples/assets/gentle-motion.mkv \
  --arg range=500ms..1500ms \
  --arg count=2 \
  --output root-bindings.mp4

repeat repeats the selected one-second range twice. The result is a two-second Video. CLI-supplied paths resolve from the current working directory. Paths written in a .clipasm file resolve from the directory containing that file.

4. Check the output

Open root-bindings.mp4 in the repository root. Confirm that it lasts two seconds. Use explicit --output because the example does not set config.output.

See Root bindings for all accepted options and Source programs and imports for the broader program model.