Turn code-made films from the Claude API into MP4s you can download
Paste the whole API reply (the chat around the code is fine) or drop an .html file anywhere on this box.
These settings change how the MP4 is made, not the film. A shorter length cuts the film off; a longer one holds its last frame. A size in a different shape from the film adds empty space around it rather than recomposing it. To change the length or shape properly, change it where the film is made and ask for a new version.
Add this to the system prompt (or the end of the brief) whenever you ask the API for a film. It makes every film render frame-perfect, with its sound.
Use desktop Chrome or Edge and keep this tab open while it renders. It usually takes less time than the film itself.
Films written with the prompt above render frame-perfect. Anything else runs on a virtual clock: the tool fakes the passing of time so each frame is drawn in order. Most canvas animations come out right, but check the result.
Only what's drawn on the canvas ends up in the video. Text or motion made with HTML and CSS won't appear. For those, record your screen instead.
Sound comes from an audio file inside the film, a __score() function or live Web Audio. You can also upload a licensed track to use instead.
Nothing is uploaded. Your film runs in a locked-down sandbox inside your browser, and the MP4 is made on your computer.
The MP4 is H.264 video with AAC sound, so it plays in PowerPoint, Keynote, QuickTime and on social platforms.