SocialKit YouTube Assemble

Renders a YouTube video from shot-list.json - images and clips scaled to the target resolution, voiceover, optional background music and subtitles - into an H.264/AAC MP4 using FFmpeg. Use when the user wants to assemble, render, stitch or export the final video file for a YouTube project.

YouTube assemble

Steps

1. Validate first: node scripts/assemble.mjs --dir <project-folder> --check It reports missing files, unsupported types, missing durations and a voiceover longer than the visuals. Fix shot-list.json or ask the user for the missing assets.
2. Render: node scripts/assemble.mjs --dir <project-folder> Output goes to output/video.mp4 unless the shot list sets output.
3. Tell the user the output path and length, and ask them to watch it. Collect changes, update the shot list or assets, and re-render with --overwrite.

Run node scripts/assemble.mjs --help for the shot list format.

Output contract

JSON on stdout with ok, output and totalSeconds, and an MP4 in the project folder.

Failure handling

• FFMPEG_MISSING: show the hint; the user installs FFmpeg or sets FFMPEG_PATH.
• OUTPUT_EXISTS: ask before re-running with --overwrite. Overwriting invalidates an existing upload approval.
• FFMPEG_FAILED: show the last lines of the error. Common causes are corrupt inputs or unsupported codecs; re-encode the asset or replace it.