Video Format Converter

What this tool does

Video Format Converter changes the container and codecs of your videos. Re-encode to H.264/AAC MP4, MKV or MOV, VP8/Vorbis WebM or MPEG-4/MP3 AVI at a chosen quality, or simply copy the existing streams into a new container in seconds when only the file type needs to change.

A video file is a container (MP4, MKV, MOV, WebM, AVI) holding streams encoded with codecs such as H.264, H.265, VP8, VP9, AAC or Opus. A file that will not play, will not import into an editor, or is rejected by an upload form usually has the wrong container or a codec the target does not support. iPhone MOV files, OBS MKV recordings and browser-made WebM files are typical examples.

This converter runs FFmpeg compiled to WebAssembly in your browser. Re-encoding produces H.264 with AAC for MP4, MKV and MOV, VP8 with Vorbis for WebM, and MPEG-4 Part 2 (Xvid-compatible) with MP3 for AVI. When the existing codecs are already allowed in the new container, the stream-copy option rewrites only the wrapper: an H.264 MKV becomes an MP4 in seconds with zero quality loss. Files stay on your device.

How to use Video Format Converter

1. Drop one or more videos onto the upload area, or click to browse.
2. Choose the target in Convert to.
3. Switch on “Copy streams without re-encoding” if you only need a different container and the codecs are compatible.
4. Otherwise choose a Quality level: High, Medium or Low.
5. Click Convert and follow the progress; Cancel stops the current file.
6. Check the preview and download each file or all of them as a ZIP.

Tips for better results

• MP4 with H.264 and AAC is the safest choice for sharing, editing software and social media.
• Try stream copy first for MKV or MOV to MP4: if it fails or the result will not play, turn it off and re-encode.
• WebM encoding in the browser is slower than H.264; use it only when a site specifically needs WebM.
• AVI is a legacy format; choose it only for old players or hardware that requires it.

Common use cases

• Converting an OBS or screen-recorder MKV into MP4 for a video editor.
• Turning an iPhone MOV into MP4 for a Windows PC or an upload form.
• Converting a WebM download to MP4 so it plays on a smart TV.
• Producing a WebM version of a clip for a website background video.

Common mistakes to avoid

• Remuxing H.265/HEVC into WebM or AVI: those containers do not support it, so the job fails. Re-encode instead.
• Expecting a format change alone to reduce size; use the Video Compressor for that.
• Converting between lossy formats repeatedly; each re-encode loses a little detail.