Which input formats are supported?

ffmpeg.wasm accepts most common video containers: MP4, WebM, MOV, AVI, MKV, FLV, and more. MP4 and WebM are the most reliably supported for both input and output.

What codecs are used for each output format?

MP4 output uses H.264 video with AAC audio. WebM output uses VP8 video with Vorbis audio. MOV output uses H.264 video with AAC audio in a QuickTime container.

WebM is the preferred format for web video — it is open, royalty-free, and natively supported in all modern browsers. It is ideal for elements on websites and for platforms like Google Drive.

MP4 (H.264) is the most universally compatible format. It plays on every device, browser, smart TV, and media player. Use MP4 when you need maximum compatibility.

MOV is the native format for Apple QuickTime and is preferred for video editing workflows on Mac. Convert to MOV when working with Final Cut Pro, iMovie, or other Apple tools.

Is my video uploaded during conversion?

No. ffmpeg.wasm runs entirely in your browser. Your video file is processed locally and never sent to any server.

How long does conversion take?

Format conversion requires re-encoding the video, which takes time in WebAssembly. Expect roughly 1–5 minutes per minute of 1080p video on a modern laptop. Using the ultrafast preset balances speed and file size.

Will converting reduce quality?

Re-encoding always involves some quality loss. This tool uses a CRF of 23 with the ultrafast preset, which provides good quality at reasonable file sizes for most content.

Video Converter

Convert videos between MP4, WebM, and MOV formats — entirely in your browser, no upload.

100% client-side · no upload

Video file (MP4, WebM, MOV, AVI…)

Load a video file to begin.

How to convert video format

Select your source video file using the file picker.
Choose the output format: MP4 for universal compatibility, WebM for web use, or MOV for Apple workflows.
Click Convert and wait for ffmpeg.wasm to process the file.
Download the converted video.

When to use each format

MP4: Best for sharing, messaging apps, email attachments, and uploading to social media. Plays everywhere.
WebM: Best for embedding in websites with a <video> tag, Google Drive, and platforms that prefer open formats.
MOV: Best for Apple device workflows, Final Cut Pro, and iMovie projects.

Related tools: Video Compressor · Video Trimmer · Video Muter · Audio Converter

常见问题

Which input formats are supported?: ffmpeg.wasm accepts most common video containers: MP4, WebM, MOV, AVI, MKV, FLV, and more. MP4 and WebM are the most reliably supported for both input and output.
What codecs are used for each output format?: MP4 output uses H.264 video with AAC audio. WebM output uses VP8 video with Vorbis audio. MOV output uses H.264 video with AAC audio in a QuickTime container.
Why convert to WebM?: WebM is the preferred format for web video — it is open, royalty-free, and natively supported in all modern browsers. It is ideal for <video> elements on websites and for platforms like Google Drive.
Why convert to MP4?: MP4 (H.264) is the most universally compatible format. It plays on every device, browser, smart TV, and media player. Use MP4 when you need maximum compatibility.
Why convert to MOV?: MOV is the native format for Apple QuickTime and is preferred for video editing workflows on Mac. Convert to MOV when working with Final Cut Pro, iMovie, or other Apple tools.
Is my video uploaded during conversion?: No. ffmpeg.wasm runs entirely in your browser. Your video file is processed locally and never sent to any server.
How long does conversion take?: Format conversion requires re-encoding the video, which takes time in WebAssembly. Expect roughly 1–5 minutes per minute of 1080p video on a modern laptop. Using the ultrafast preset balances speed and file size.
Will converting reduce quality?: Re-encoding always involves some quality loss. This tool uses a CRF of 23 with the ultrafast preset, which provides good quality at reasonable file sizes for most content.

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