Video format converter

What it does

Re-encodes a video file from one container/codec to another. The tool reads the source via WebCodecs, decodes each frame, and re-encodes into the target format using the browser's native encoder.

Supported targets:

• MP4 (H.264 / AVC) — universal compatibility. Plays everywhere, embeds anywhere. Larger files than VP9.
• WebM (VP9) — modern open codec. ~30 % smaller than H.264 at the same quality. Plays in all modern browsers, native in Chrome / Firefox / Edge.
• WebM (VP8) — older but extremely compatible (including some IoT and embedded video players). Larger than VP9.

When you'd use this

• Converting a screen recording from MOV to MP4 for upload to platforms that reject MOV.
• Shrinking a video to WebM to save bandwidth on a self-hosted page.
• Producing both an MP4 and a WebM source for a <video> tag with multiple <source> children (max compatibility).
• Stripping an unusual container (.flv, .avi if your browser can decode it) into a modern web-friendly file.

Quality control

The encoder runs at a fixed bitrate per resolution by default (~4 Mbps for 1080p, ~2 Mbps for 720p). A "high quality" toggle doubles the bitrate; "low quality" halves it.

For finer control, use the Video compressor which exposes explicit quality presets.

Limits

• Browser support varies. H.264 encoding requires Chrome / Edge with hardware encoder support, or Firefox 130+. Safari supports H.264 via VideoToolbox. WebM encoding works everywhere modern.
• No audio support yet — current versions of WebCodecs encode video only. The original audio track is preserved by re-muxing if possible, but for some source containers the audio is dropped. The output preview will show "no audio" if that happens.
• Maximum file size depends on browser memory. Modern desktops handle 4K source files fine; phones may struggle on long 4K clips.

Privacy

All decode and encode runs in your browser. No file is uploaded.

Related

• Video compressor
• Video resizer
• Video format comparison
• Supported formats