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MP4 → FLV

MP4 to FLV Converter

Convert MP4 video to FLV entirely in your browser — no upload, no watermark, no sign-up.

Drop files here

or browse from your device

images · audio · video · documents · archives · up to ~500MB

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Your first conversion lands here automatically — saved on this device only, never uploaded.

100% Private

Runs in your browser. No upload.

Instant

No queue, no server roundtrip.

Offline-ready

Works after first load.

Why convert MP4 to FLV?

Re-wrapping MP4 footage as FLV is what makes it playable and editable outside the device or era it came from, without re-shooting anything. FLV (Flash Video) earns its place here: historic small-size streaming — today mostly a reason to migrate. MP4 with H.264 video and AAC audio is the closest thing video has to a universal format. Phones, TVs, browsers, editors and every social platform accept it without complaint.

MP4 with H.264 video and AAC audio is the closest thing video has to a universal format. Phones, TVs, browsers, editors and every social platform accept it without complaint.

When MP4 → FLV is the right move

  • An editor, phone or TV plays FLV smoothly but stutters on MP4 — or refuses it outright.
  • You are uploading somewhere that lists FLV as a supported format and MP4 as unsupported.
  • Old MP4 footage needs to become something you can still open in five years.

Quality, size and what changes

Picture and sound are re-encoded into the FLV container at a bitrate chosen to keep the result visually close to the MP4 source. Resolution, frame rate and duration are preserved; file size usually changes noticeably because MP4 and FLV lean on different codecs. Multiple audio tracks or chapter data may not carry over.

What you gain with FLV: Historic small-size streaming — today mostly a reason to migrate.

How it works

Drop your MP4 file above and Morphio decodes it locally, then re-encodes it as FLV using WebAssembly + the browser's native codecs. Nothing is ever uploaded — your files stay on your device. Batch as many files as your machine can handle. See exactly how in-browser conversion works.

MP4 to FLV — frequently asked questions

How do I convert MP4 to FLV without uploading the file?

Open the MP4 to FLV page, drop your video on the drop zone and press convert. Morphio runs an FFmpeg build compiled to WebAssembly that runs inside the page, so the MP4 data never leaves your device and no server ever receives a copy.

Does converting MP4 to FLV lose quality?

Audio and video tracks are re-encoded together, so the result stays in sync and plays on standard players. Converting MP4 to FLV only rewrites the container and encoding you asked for — the source file on your disk is never modified.

Is the MP4 to FLV converter free, and how big can the file be?

Yes. The free plan covers 10 conversions a day with files up to 200 MB and adds no watermark or sign-up. Morphio Pro ($5/month, or $29 once for lifetime access) removes the daily cap and raises the per-file limit to 5 GB.

Does converting MP4 to FLV lose quality?

Morphio decodes the MP4 file at full fidelity and re-encodes it at a high-quality FLV setting, so the difference is normally invisible or inaudible. What conversion cannot do is recover detail the original MP4 file already threw away.

Can I convert several MP4 files to FLV at once?

Yes — drop the whole batch in and each file is processed in turn on your own machine. The practical limit is your device's memory and patience, not a server quota, because nothing is queued anywhere else.

Are my MP4 files uploaded anywhere?

No. The conversion runs entirely inside your browser using WebAssembly, so the file never leaves your device — you can disconnect from the internet after the page loads and it still works.

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