My browser screen recording has no sound in the MP4 — why?

If the original WebM has no audio track (many screen recorders capture video only), the MP4 will be silent too. The tool converts what's there; it can't invent a missing track.

Are my files uploaded?

No. The first time you use an audio/video tool, your browser downloads the open-source FFmpeg engine — a 32 MB file, roughly 10 MB once your connection compresses it — as a static file, and that is the only network traffic. Your media files are then processed entirely on your device and never reach a Filesvo server.

Why is processing slower than a desktop app?

The FFmpeg engine runs inside your browser's WebAssembly sandbox on a single thread, which is several times slower than a native install. Short clips finish quickly; re-encoding long videos can take minutes. The progress bar shows the honest state, and you can cancel at any time.

Does this work on phones?

Yes on recent devices, with limits: the engine is a 32 MB file (roughly 10 MB compressed in transit), and phones have less memory available to the browser, so large videos can fail on mobile. If a file fails on your phone, try a smaller file or a desktop browser. The 100 MB per-file limit applies everywhere.

Convert WebM to MP4 Online

WebM is common for browser screen recordings and web downloads, but iPhones, iPads and many editing apps won't open it. This tool re-encodes WebM's VP8/VP9 video and Opus/Vorbis audio into a standard H.264/AAC MP4.

or drag and drop a .webm file here — up to 100 MB

This tool runs the open-source FFmpeg engine in your browser. First use downloads it once (a 32 MB file, roughly 10 MB compressed in transit); after that it loads from your browser cache. Your files are never uploaded. The engine is ffmpeg.wasm, distributed unmodified under the GPL-2.0-or-later.

Processed on your device — files are never uploaded to Filesvo.

How to use Filesvo

Select or drop a WebM video (up to 100 MB).
Click Convert to MP4 and let the re-encode run — progress is shown honestly.
Download an MP4 that plays on any device.

About WebM-to-MP4 conversion

WebM uses the VP8 or VP9 video codec with Opus or Vorbis audio — codecs that can't be placed into an MP4 container with any real player support. Conversion therefore always means re-encoding, not repackaging, and this tool says so instead of pretending otherwise.

Output is H.264 at CRF 23 with 128 kbps AAC audio: visually faithful for screen recordings and camera footage alike, and compatible with everything from iMessage to PowerPoint.

The FFmpeg command this runs

This tool is FFmpeg itself, compiled to WebAssembly and running in your browser. Below is the command it builds with the options set as they arrive — generated from the same code that performs the conversion, not written out by hand, so it cannot drift out of date. Paste it into a terminal with FFmpeg installed and it does the same job there.

ffmpeg -y -i input.webm -vf "scale=trunc(iw/2)*2:trunc(ih/2)*2" -c:v libx264 -preset veryfast -crf 23 -pix_fmt yuv420p -c:a aac -b:a 128k -movflags +faststart output.mp4

The input and output names are placeholders. Your own filenames are used inside the browser, and neither file leaves your device.

Private by design

Your files are processed directly in your browser using the open-source FFmpeg engine compiled to WebAssembly and are not uploaded to Filesvo. Nothing is stored on our servers, because nothing ever reaches them.

The engine is a static file your browser downloads once and then caches — the only network request this tool makes. It is used exactly as its authors published it; see the engines and their licences.

Frequently asked questions

My browser screen recording has no sound in the MP4 — why?: If the original WebM has no audio track (many screen recorders capture video only), the MP4 will be silent too. The tool converts what's there; it can't invent a missing track.
Are my files uploaded?: No. The first time you use an audio/video tool, your browser downloads the open-source FFmpeg engine — a 32 MB file, roughly 10 MB once your connection compresses it — as a static file, and that is the only network traffic. Your media files are then processed entirely on your device and never reach a Filesvo server.
Why is processing slower than a desktop app?: The FFmpeg engine runs inside your browser's WebAssembly sandbox on a single thread, which is several times slower than a native install. Short clips finish quickly; re-encoding long videos can take minutes. The progress bar shows the honest state, and you can cancel at any time.
Does this work on phones?: Yes on recent devices, with limits: the engine is a 32 MB file (roughly 10 MB compressed in transit), and phones have less memory available to the browser, so large videos can fail on mobile. If a file fails on your phone, try a smaller file or a desktop browser. The 100 MB per-file limit applies everywhere.

MP4 to WebM

Convert MP4 videos into open-format WebM (VP8/Vorbis) files for royalty-free web embedding.

MOV to MP4

Convert QuickTime MOV videos — including iPhone recordings — into MP4 files that play everywhere.

Compress Video

Shrink MP4, MOV and WebM videos with a quality you choose, plus an optional 720p cap — with honest before/after sizes.