FLV to Y4M Converter
Processing entirely on your device — large files may take a moment.
Convert Y4M raw video to MP4/WEBM with real compression. If your files are still in FLV format, this page is the shortcut: FLV is the Flash-era video container from thousands of old video sites and screen recordings. Modern players have dropped it.
iLoveConverter processes everything locally on your computer, which makes it private and fast: no upload wait, no server storage, no limits. Add as many files as you like — batch conversion is built in.
How FLV compares to Y4M
| FLV | Y4M | |
|---|---|---|
| Compatibility | Legacy players only | ffmpeg, x264, vapoursynth |
| Best for | Early web video archives | Filter-pipeline interchange |
How to convert FLV to Y4M
- 1
Select your files
Drag & drop your FLV files onto the area above, or click to browse. You can add multiple files at once for batch conversion.
- 2
Convert instantly
Click "Convert to Y4M". The conversion runs entirely inside your browser using WebAssembly — no upload, no queue, no waiting.
- 3
Download results
Download each converted Y4M file individually, or grab everything at once as a ZIP archive.
About the FLV format
FLV (Flash Video) was the video format of the early streaming web — YouTube's original delivery container from 2005 to ~2010, played by Adobe Flash Player. Later versions carried H.264/AAC, but the container lived and died with Flash, which reached end-of-life in 2020.
Modern browsers cannot play FLV at all, and only niche players (VLC) bother. If you have an FLV archive, converting to MP4 recovers the same H.264 video into a container every device accepts.
+ Strengths
- ✓Only relevant for early-web video archives
! Limitations
- −Dead ecosystem — Flash ended in 2020
- −No browser support at all
About the Y4M format
Y4M (YUV4MPEG2) is uncompressed video with a one-line text header: resolution, framerate and color space, then raw YUV frames. It is the lingua franca of video-filter pipelines — AviSynth, Vapoursynth and encoder test suites pass frames around as Y4M because there is nothing to misparse.
A Y4M of any real length is enormous (30MB per second of 1080p), so conversion to MP4/WEBM with H.264 or VP9 is always the destination — the value is in the zero-ambiguity input, not the format itself.
+ Strengths
- ✓Zero-ambiguity pixel format declaration
- ✓Standard between filter frameworks
- ✓Lossless by construction
! Limitations
- −No compression whatsoever
- −Color space variants (limited/full) trip decoders
- −Not natively playable in browsers
Why convert FLV to Y4M?
Think of it as moving your file to the container that fits the job. Dead ecosystem — Flash ended in 2020 Y4M works differently: Zero-ambiguity pixel format declaration If any of that sounds like your task, run the conversion — it takes seconds and nothing leaves your device.
Frequently asked questions
Is this FLV to Y4M converter really free?
Yes — completely free, with no sign-up, no watermark and no daily conversion limits. The site is supported by advertising.
Are my files uploaded to a server?
No. The conversion runs entirely inside your browser using WebAssembly, so your files never leave your device — that is what makes it instant and private.
Does it work on Windows, Mac, iPhone and Android?
Yes. Anything with a modern browser works: Windows, macOS, Linux, Android and iOS. No software installation is required.
Is there a file size limit for FLV to Y4M?
The only limit is your device's memory, since nothing is uploaded. Files up to a few hundred megabytes work fine on a modern desktop browser; very large files simply take a little longer.
Will the audio track be kept?
Yes. The audio is carried over and re-encoded to the standard audio codec of Y4M, staying in sync with the video. If your FLV file has multiple audio tracks, the first one is used.
Why is video conversion slower than image conversion?
Every frame has to be decoded and re-encoded. This site runs that work on your own CPU via WebAssembly — nothing is uploaded, but a multi-minute video reasonably takes a few minutes. Images, by comparison, are single-frame jobs.