Free tool
Free FLV to MP4 converter for old Flash video
Convert FLV to MP4 in your browser.
Your video
Drag a file here, paste it, or choose one.
.flv, .mp4, .mov, .m4v, .mkv, .webm, .avi, .wmv, .3gp, .gif. Up to 500 MB.
Up to 10 minutes long.
Your video never leaves your browser. The conversion runs on this machine.
More options
Result
Worked example
Measured on our own 13 second Sorenson Spark FLV at 640 by 360, converted to MP4 at Balanced.
Source FLV
920 KB
MP4, H.264 and MP3
216 KB
Sorenson Spark has to be re-encoded, and H.264 needed under a quarter of the space. A later style FLV holding H.264 and AAC went the fast route instead: rewrapped in 2 seconds with no re-encode.
1. Add the FLV. 2. Keep fast mode on. 3. Convert locally. 4. Download the MP4.
What Interlace does
Turn the old webinar into a short explainer.
- Paste the transcript or upload the slides
- Interlace keeps what matters and draws each scene
- A short video people will actually finish
Real Interlace output, unedited. Shown silent and sped up.
Your file
webinar-archive.flv
Flash Video, 2011
Questions
Asked and answered
No. The file is opened by the page and converted by ffmpeg compiled to WebAssembly, on your own machine. There is no upload step, and closing the tab discards everything.
It depends on what is inside, and the page checks before it starts. Sorenson Spark and VP6, from the earlier Flash years, are re-encoded to H.264. H.264 with AAC or MP3, from the later years and from stream recorders, is copied into the MP4 untouched.
VLC still opens FLV files. Browsers, phones and most editors do not, which is why converting once is usually less trouble.
F4V was Adobe's later Flash format and is built like an MP4. Rename it to .flv or .mp4 and drop it in; the page reads what is inside either way.
Some early FLVs used the Nellymoser codec for microphone audio, which was low quality to begin with. The MP4 gets the same sound converted to AAC; it cannot sound better than the recording did.
500 MB and 10 minutes. Everything runs inside one browser tab, which has a fixed memory budget, and the encoder runs on a single thread. A rewrap takes seconds; a full re-encode runs at about real time for 720p and several times the clip length for 1080p. For anything bigger, a desktop encoder such as HandBrake is the better tool.
Turn this into a video
Create an account and start from a document, script, or prompt.