Convert FLV to MP4
Flash is gone, but many saved videos and old recordings are still FLV files. Convert them to MP4 so they play again on phones, computers and TVs.
- No upload
- No watermark
- No file size limit
- Hardware accelerated
Drop videos here to convert them
MP4, MOV, WebM, MKV, AVI and more · no size limit or watermark
Processed on your device. Your videos are never uploaded.
Advanced: codec, frame rate, audio, trim
How to convert FLV to MP4
- 1
Add FLV files
Drop one or more .flv videos onto the tool.
- 2
Choose the quality
High re-encodes to H.264 for maximum compatibility. If your FLV already contains H.264, “Original” copies it without loss.
- 3
Convert
FLV is read by the built-in compatibility engine, which downloads once (about 30 MB) and runs on your device.
- 4
Download
Save the MP4 files individually or as a ZIP.
Why FLV files no longer play
FLV was the format of Adobe Flash Player, which powered most web video in the 2000s. Adobe ended support for Flash at the end of 2020, and browsers removed it. Phones never played FLV natively, so files saved from that era, game capture software and some streaming tools are now hard to open.
MP4 is the natural replacement – it is what the web switched to when Flash disappeared.
Fast copy or re-encode?
Later FLV files contain H.264 video with AAC audio – the same streams MP4 uses. With “Original” quality those streams are copied into an MP4 container, which takes seconds and keeps the exact quality.
Older FLVs use the Sorenson Spark or VP6 codecs. Those can’t go into an MP4, so they are re-encoded to H.264. This is done in software and is slower, but it makes the video playable everywhere.
Live stream recordings
Some streaming and recording tools write FLV because a partly written FLV survives a crash. Converting the recording to MP4 afterwards makes it easy to edit, upload to video platforms or share in a chat.
Rescuing an old video archive
Found a folder of FLV files on an old hard drive? Add them all at once. They are converted one at a time, each keeps its file name with a .mp4 extension, and you can download the whole set as a ZIP. Keep the FLV originals until you have checked that every MP4 plays as expected.
Frequently asked questions
Is FLV to MP4 conversion lossless?
Yes, for FLV files with H.264 video when you choose “Original” quality. Older codecs need re-encoding, which the High preset keeps visually faithful.
Can I convert an FLV link from a website?
No. Asset Compressor only works with files that are already on your device.
How long does it take?
A stream copy finishes in seconds. Re-encoding runs in software and takes longer – roughly a few minutes for a typical clip on a laptop.
Are my files uploaded?
No. The conversion happens in your browser, and the files never leave your device.
Related tools
AVI to MP4
AVI files from old cameras, DivX and Xvid downloads or Windows-era recordings often won’t play on phones or in browsers. Convert them to MP4 right on your device.
MKV to MP4
MKV is great for storing video but many TVs, phones and editing apps won’t open it. Remux it to MP4 in seconds without touching the picture quality.
Video converter
Change a video’s format in seconds. When the codecs allow it, the streams are copied without re-encoding, so the quality stays exactly the same.
Compress video
Shrink MP4, MOV, WebM and MKV files on your own device with hardware-accelerated encoding. Choose a quality level or an exact target size – no upload, no watermark.
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