F4V to FLV converter
Convert F4V to FLV in seconds, free and unlimited. No upload, no sign-up, no watermark: your video never leaves your device.
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Quick answer: To convert F4V to FLV, add the F4V file to the iHateFiles F4V to FLV converter and press Convert. The conversion runs in your browser, so the file is never uploaded, and it is free with no sign-up, watermark or size limit. F4V is a format most software has stopped opening. FLV is not.
Should you convert F4V to FLV?
Yes. F4V is a format most current software no longer opens, so converting it is the reliable way to keep watching it. FLV is a reasonable target; MP4 is the safest.
The picture is re-encoded
An F4V usually holds H.264 video with AAC sound in a Flash wrapper. This writes Sorenson Spark (FLV1) video with MP3 sound into the FLV. Both sides are compressed with loss, so this is a second generation: leave the quality at its default or higher, because the encoder is working from F4V artefacts rather than the original.
Expect a larger FLV
FLV uses Sorenson Spark (FLV1) video, an older and less efficient codec than an F4V normally holds. Matching the look takes more bytes, so the file grows. Do it for compatibility with whatever needs FLV, not to save space.
Where the FLV will play
FLV plays on VLC and very little else since Flash was retired in 2020.
F4V and FLV side by side
| F4V | FLV | |
|---|---|---|
| Inside the file | H.264 video with AAC sound in a Flash wrapper | Sorenson Spark (FLV1) video with MP3 sound |
| Compression | Lossy | Lossy |
| Carries sound | Yes | Yes |
| Plays on | Needs converting first | VLC and very little else since Flash was retired in 2020 |
| Here | Read only | Read and write |
What usually goes wrong
About the F4V. Renaming .f4v to .mp4 very often just works, because it already is one.
About the FLV. If you have FLV files they are probably old downloads worth rescuing, and converting them to MP4 is the way to keep them watchable.
How to convert F4V to FLV
- Add your F4V file. It is read from your disk and stays there.
- Check the settings. The output format is already set to FLV.
- Press convert and the FLV file is saved back to your device.
Questions
How do I convert F4V to FLV?
Open this page, add your F4V file, and press convert. The file is decoded and re-encoded by your own browser and saved back to your device. Nothing is uploaded.
Is this F4V to FLV converter free?
Yes, completely. There is no account, no sign-in, no watermark and no daily limit, because there is no server doing the work. Your own device does it.
Are my files uploaded anywhere?
No. There is no upload endpoint. The conversion runs inside this browser tab, so your file never leaves your device. You can open your browser's network panel and watch: nothing carrying your file is sent.
Is there a file size limit?
No fixed limit. Because the work happens on your machine there is no server quota. The only ceiling is your own device's memory, which for video means very large files may be slow.
Will converting to FLV lose quality?
FLV is a lossy format, so some detail is discarded. The quality control on this page decides how much. The default is set high enough that most people cannot see the difference.
Can I convert several F4V files at once?
Yes. Add as many as you like and they are converted one after another, then offered as a single ZIP.