Audio & video / Local FFmpeg tool
Cut a precise section from an audio file using start time and duration.
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.
At most 60 download files are generated.
Validated downloads will appear here after processing.
Method, example & boundaries
Cut a precise interval from a local audio file by start time and duration, then export that interval as MP3. The page validates the interval against probed source duration and re-encodes the cut, so the requested boundary is not silently moved to a container keyframe.
One approximately 30-second MP3 containing the interval from 02:15 to 02:45.The end is derived as start plus duration. Both values must fit inside the measured source timeline before processing begins.
The local FFmpeg worker probes duration, seeks to the requested start, decodes the selected interval, and encodes it with the chosen MP3 bitrate. Output duration is checked before the completion event is recorded.
Local AI / Speech to text
Open-source Whisper Tiny runs in your browser. The file, audio and result are never uploaded.
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.
How it works
The selected interval is decoded and re-encoded as MP3 so cuts are not limited to source keyframes.
The selected interval is decoded and re-encoded as MP3 so cuts are not limited to source keyframes. 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.
The interval must stay within the detected source duration. 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.
Anonymous feedback
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