Y4M to FLV converter
Convert Y4M to FLV in seconds, free and unlimited. No upload, no sign-up, no watermark: your video never leaves your device.
Last updated
Quick answer: To convert Y4M to FLV, add the Y4M file to the iHateFiles Y4M 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. Y4M is a format most software has stopped opening. FLV is not.
Should you convert Y4M to FLV?
Yes. Y4M 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
A Y4M usually holds completely uncompressed frames with no sound. This writes Sorenson Spark (FLV1) video with MP3 sound into the FLV. The source is uncompressed, so this is the first and only round of loss.
There is no sound to carry
A Y4M carries no audio track, so the FLV comes out silent. If the sound exists as a separate file, add it afterwards with the Replace Audio tool.
Expect a smaller FLV
Sorenson Spark (FLV1) video is a much more efficient codec than what a Y4M holds, so at the same visual quality the FLV is usually a third to a half of the size.
Where the FLV will play
FLV plays on VLC and very little else since Flash was retired in 2020.
Y4M and FLV side by side
| Y4M | FLV | |
|---|---|---|
| Inside the file | completely uncompressed frames with no sound | Sorenson Spark (FLV1) video with MP3 sound |
| Compression | Lossless | Lossy |
| Carries sound | No | 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 Y4M. A few seconds of Y4M can be larger than a whole film in MP4. That is the format doing its job.
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 Y4M to FLV
- Add your Y4M 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 Y4M to FLV?
Open this page, add your Y4M 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 Y4M 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 Y4M files at once?
Yes. Add as many as you like and they are converted one after another, then offered as a single ZIP.