FLV to MP4 converter

Flash Player is gone, so FLV downloads and old stream recordings need a modern container.

Drop a FLV file hereThe converter loads in your browser.

What happens to your FLV

FLV files that contain H.264 + AAC are remuxed instantly. Sorenson Spark or VP6 video is re-encoded to H.264.

Tip: Recordings made with RTMP streaming tools are often already H.264, so they convert in seconds.

How to convert FLV to MP4

  1. Drop your FLV file on the box above, or tap it to pick one. The engine (about 31 MB) loads once per visit.
  2. The converter reads the file's streams and shows which codecs are inside.
  3. Keep the defaults, or pick a quality and resolution.
  4. Press the button, wait for the progress bar, then download your MP4.

Prefer the command line?

This is the FFmpeg command the converter runs for a typical FLV (h264 + aac). Paste it into a terminal with FFmpeg installed for batch jobs or files too big for a browser tab:

ffmpeg -y -i input.flv -map 0:v:0 -map "0:a:0?" -sn -dn -c:v copy -c:a copy -movflags +faststart output.mp4

Streams are copied (-c copy), so this runs at disk speed. Your own file may contain different codecs; the converter above detects them and adapts. For other jobs, ask the FFmpeg command helper.

Questions

Why is my FLV conversion instant?

Your FLV already held H.264 + AAC, so it was copied straight into MP4.

Is my FLV file uploaded?

No. The FLV is read from your device by FFmpeg running as WebAssembly in the page, and the MP4 is written back to your device. No server ever receives it.

Is there a size limit for FLV to MP4?

We set none. The practical limit is browser memory: roughly 2 GB of output on a computer, and much less on phones.