How to use it
- Add your files. Drop MP4 files on the page or use Choose files. Folders and ZIPs work too.
- Check that FLV is selected. FLV is already chosen on this page.
- Adjust options if you need to. Quality, size and other settings appear when the format has them.
- Convert and download. Press Convert; with several files, “Download all” gives you one ZIP.
What happens to your file
The MP4 file is opened in your browser and its video and sound are re-encoded into FLV. Common formats use the browser’s built-in encoders (fast, hardware-accelerated); others use FFmpeg compiled to WebAssembly, which downloads once (about 32 MB) and then works offline.
Resolution and frame rate are kept. Re-encoding a lossy video loses a little detail, so choose the highest quality setting if you will edit the result.
About MP4 and FLV
MP4: MP4 is the most widely supported video format: phones, browsers, TVs and every editor play it.
FLV: FLV is the Flash Video format from the early web video era.
Questions
Is my MP4 file uploaded?
No. The conversion runs inside this browser tab, and the FLV is created on your device. Nothing is sent to a server.
Is there a file size limit?
No fixed limit: files are processed by your device, so very large videos depend on its memory. Computers handle several GB; phones are best with smaller files.
Can I convert several MP4 files at once?
Yes. Drop as many as you like, a folder or a ZIP; “Download all” saves every FLV in one ZIP.