Convert FLV to MP4
Flash is gone, and the FLV files left on old drives will not open in anything. Every codec they used is supported — Sorenson Spark, VP6, H.264, MP3, AAC, Nellymoser and Flash ADPCM — and they come out as MP4 files that play normally.
- Never stored
- No queue, no waiting
- No signup, no watermark
How it works
Add your FLV
Drop the file, or an F4V. The codecs inside are named for you.
Let it convert
Old Flash video is decoded and re-encoded as H.264; H.264 inside an FLV is copied across untouched.
Download the MP4
A normal video file again, playable on anything.
Rescuing files from a platform that no longer exists
Flash was switched off at the end of 2020 and the plugin removed from every browser, which left a great many .flv files that nothing will play. Converting them is genuinely an archival job, and how it goes depends entirely on when the file was made.
From Flash Player 9 onwards — roughly 2007 — an FLV usually holds H.264 video with AAC sound, which is exactly what an MP4 holds. Those convert by moving the tracks across untouched: seconds, and nothing lost. Most FLVs anyone still has fall into this group, since it covers the era when video sharing was at its peak.
Older files hold Sorenson Spark or VP6 — the codecs Flash used before H.264 — and those have to be decoded and re-encoded, which takes real time and costs a generation. It is worth tempering expectations there rather than blaming the conversion: this is footage that was made small for a 2005 internet connection, and a bigger modern screen makes that obvious. No converter improves it, and any that claims to is inventing detail.
Two things genuinely cannot be read, and the page says so rather than failing vaguely. Flash Screen Video, used for screencasts and recordings of presentations, and Speex, an old speech codec — both are dead ends that no current decoder implements. Cue points, the markers Flash used to trigger events partway through a video, are dropped along with the rest of the Flash-specific metadata, because nothing outside Flash ever read them.
When you want something else
ffmpeg handles the formats this cannot and is the right tool for a folder of recovered files: ffmpeg -i in.flv -c copy out.mp4 remuxes the modern ones instantly, and it will fall back to a re-encode automatically when the codec needs it. For Flash Screen Video and Speex, ffmpeg is more or less the only thing left that still decodes them at all.
For the F4V variant — Adobe's later format, already MP4 underneath — renaming the file to .mp4 is frequently the entire conversion. It costs nothing to try before converting anything.
Frequently asked questions
How can this open a file even VLC struggles with?
This page carries its own support for these old formats rather than relying on what the browser can play, so a 2007 Flash recording opens here — without installing anything.
Is my file stored anywhere?
No. Nothing is stored at any point.
The recording has terrible sound. Will this fix it?
No tool can add detail that was never recorded — Nellymoser speech sound is very low quality by design. It is decoded faithfully and written as AAC, so it will sound the same, and finally play.
Why is the picture small?
Flash video was usually 320×240 or 480×360. The original size is kept, because enlarging it only makes the blur bigger. Any player can scale it up if you want it bigger on screen.
What about the sound being out of step?
FLV timestamps are often irregular. Both tracks are rebuilt on one clock from the file's own timestamps, which fixes the drift that made these recordings so hard to watch.
Do screen-recorded FLVs work?
Flash Screen Video is not in this build, so those files are refused with a clear message rather than converted into mush. Everything else — Spark, VP6 and H.264 — works.
Good to know: Flash Screen Video (codecs 3 and 7) and Speex sound are not supported. Cue points and Flash metadata are dropped; the video and sound are what comes across.
Put this tool on your website
Free for any blog, class page or help article. Paste one snippet and your visitors can use it right on your page.