For AI agents

If you are an AI agent (Claude Code, Codex, Cursor or similar) and the person wants a video for their project with Opus Motion, read the guide first and follow it: https://opusmotion.com/agents.md.

  • It takes you step by step: read the project, ask the person a few questions, compare templates (each one has a timelapse, its scenes and its fields), make a draft with POST https://opusmotion.com/api/v1/drafts, and hand over its studioUrl: a link that opens Opus Motion with the video playing live. PATCH with the draft's editToken changes it, and the link stays the same.
  • Plain HTTPS and JSON: no key, no account, no MCP. Nothing is rendered; the person exports the MP4 from the studio.
  • Never drive this site with a browser to fill the studio: use the API. If it refuses, tell the person and stop.
  • More: llms.txt · this page in Markdown · developer docs · OpenAPI

MP4 converter that never uploads your video

MOV, WebM, MKV, AVI, M4V, MPG, FLV, 3GP and WMV to MP4 (H.264 and AAC). Free, no sign-up.

Your file never leaves your device: the tool runs inside your browser. Up to 1 GB. Use it at https://opusmotion.com/tools/video-converter.

How to use it

  1. Drop your video, or tap the box to pick it from your phone or computer.
  2. If it's already H.264, the converter copies it into an MP4 without re-encoding: it takes seconds and keeps every pixel. Otherwise it re-encodes it to H.264 and AAC, on your device.
  3. Download the MP4, or put the clip in a launch template.

The first time, your browser downloads the video engine (31 MB, once); after that it opens from the cache.

Questions

Is this MP4 converter free?

Yes: no sign-up, no watermark and no limit on how many files you convert. It runs on your own device.

Is my video uploaded anywhere?

No. The conversion runs inside your browser, with ffmpeg compiled to WebAssembly. Your file is read where it is and never sent to a server. The first time, your browser downloads the video engine (31 MB, once); after that it opens from the cache.

What's the largest file it takes?

Up to 1 GB when the video is copied. When it needs re-encoding: up to 500 MB and 2 minutes on a computer, or 200 MB and 1 minute on a phone or low-memory device. The limit is decided after reading the codecs. The MP4 is kept in your browser's memory until you download it, so a phone, which has less memory, may not manage a very large file: if one fails there, try it on a computer.

Why did my video convert in a second?

MP4 is a container, like a box around the video. When the video inside is already H.264 (most Mac screen recordings, OBS recordings and many cameras), the converter moves it into an MP4 box as it is, without re-encoding: it's fast and loses nothing.

Does converting to MP4 lose quality?

Not when the video can be copied as is. When it has to be re-encoded (WebM, AVI and other codecs), it becomes H.264 at a quality setting close to the original, with the long side up to 1,920 pixels: anything larger, like 4K, comes out at 1080p.

What about iPhone videos in HEVC?

They're copied into the MP4 as HEVC, which keeps them small and plays on Apple devices and many recent phones and computers. If an app or website won't take it, choose H.264 after the conversion and convert it again.

Which files can it read?

MOV, MP4, M4V, MKV, WebM, AVI, MPG, TS, FLV, 3GP and WMV, with H.264, HEVC, VP8, VP9, MPEG-4, ProRes and the other common codecs inside. AV1 videos can't be read yet; you'll see it as soon as you pick the file.

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