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Audio & video / Local FFmpeg tool

Video to MOV Converter

Create an H.264/AAC QuickTime MOV file locally with adjustable CRF quality.

● Files stay in your browser
Files stay in your browser

The first run loads an approximately 31 MB FFmpeg WebAssembly core from this site. It does not use a CDN or upload your files.

Files are limited to 200 MB total and 20 minutes; mobile devices use an 80 MB limit. Reverse, GIF and boomerang tools have lower duration caps.

Choose files, set the controls, then start.Progress: 0%

Processed result

The first run loads an approximately 31 MB FFmpeg WebAssembly core from this site. It does not use a CDN or upload your files.

Validated downloads will appear here after processing.

Method, example & boundaries

Video to MOV Converter: from input to a reviewable result

Create a QuickTime MOV file in the browser by re-encoding the first video stream as H.264 and optional audio as AAC. The workflow targets predictable compatibility and fast-start delivery; it does not claim to create a professional ProRes master.

Worked example: MP4 handoff at CRF 23

Example input
1920×1080 MP4 with H.264 video and AAC audio; quality control CRF 23.
Example output
A .mov container with yuv420p H.264 video, optional 128 kbps AAC audio, and fast-start metadata.

How to interpret it

Even when the codecs already look similar, the current workflow re-encodes streams for a deterministic result; it is not a lossless container-only remux.

Video encoding plan

The worker maps the first video stream and an optional first audio stream, encodes libx264 with the selected CRF and ultrafast preset, uses yuv420p for compatibility, encodes AAC at 128 kbps, and moves metadata for progressive playback.

MOV delivery boundaries

  • The output is H.264/AAC in MOV, not ProRes, DNxHR, or an archival master.
  • Re-encoding is lossy and can be slow or memory-heavy on long high-resolution video.
  • Only the first video and optional first audio stream are retained; extra tracks are not copied.

Local AI / Speech to text

Transcribe the current audio or video

Open-source Whisper Tiny runs in your browser. The file, audio and result are never uploaded.

◎ First use loads about 64 MB of model and runtime files

Choose an audio or video file in the workbench above first.

◎ The model loads only from 321Kit; MiniMax is not called and no transcript history is stored.

Transformers.js + Whisper Tiny (Apache-2.0)

Transcript

How it works

Video to MOV Converter

MOV changes the delivery container while re-encoding streams for predictable compatibility.

How does this tool process my file?

MOV changes the delivery container while re-encoding streams for predictable compatibility. Processing uses single-thread FFmpeg.wasm. The page does not upload, store or inspect file content outside this device. Cancel, error and page close terminate the worker and revoke temporary object URLs.

What limits apply to the output?

Output is not ProRes; it uses H.264 video and AAC audio. Files are limited to 200 MB total and 20 minutes; mobile devices use an 80 MB limit. Reverse, GIF and boomerang tools have lower duration caps.

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