Video Format Converter

The Video Format Converter runs FFmpeg, compiled to WebAssembly, inside your browser. Choose a video file, pick a target format, optionally keep only part of the timeline, and click "Start conversion". Targets include common video formats, animated GIF and WEBP, and audio-only outputs: MP3, WAV, AAC/M4A, FLAC and OGG. Keep in mind that running in a browser is much slower than desktop FFmpeg, so it suits shorter clips, and the first use needs a download of roughly 25 to 30 MB for the processing core.

How to use it

1. Click the dashed area "Click to upload a video" and choose the file. Its name then appears in the area.
2. Choose the output in the "Target format" dropdown. Video options are MP4, WEBM, AVI, MOV, MKV, FLV, WMV, OGV, 3GP, M4V, TS and MPG. Animated options are GIF and animated WEBP. Audio-only options are MP3, WAV, AAC/M4A, FLAC and OGG, which drop the picture and keep the sound.
3. To convert just a section, fill in "Trim start" and "Trim end" using a format such as 00:00:05 and 00:00:15. Leave both empty for the whole video; fill only the start to go from there to the end; fill only the end to go from the beginning to that point.
4. Click "Start conversion". On the first run the button reads "Downloading processing core…", then "Converting… N%" with progress.
5. When it finishes, a preview (video, audio or animation) appears. Click "Download result" to save a file named converted plus the matching extension (the AAC option is saved as .m4a).
6. If you see "Conversion failed. Please try again or use a different source file", try another target format, a shorter section, or check that the source file is intact.

A practical scenario

Say you want to turn a phone screen recording into an animation you can send in a chat. Upload the recording, choose GIF, enter a start and end that cover about 5 to 10 seconds, and click "Start conversion". The tool always makes animations at 10 frames per second and 480 pixels wide with the original proportions, which keeps files manageable but also means a small, not very smooth picture with no sound. Or say you only want the audio from a lecture recording: choose "MP3 (audio only)" and you get an audio-only file without installing other software. Time depends on length, resolution and your device, so try a short section first.

Which codecs each format uses

• MP4, MOV, MKV, M4V and TS: H.264 video (libx264) with AAC audio. TS is explicitly muxed as an MPEG transport stream.
• WEBM: VP9 video (libvpx-vp9) with Opus audio. VP9 encoding is very slow in a browser, so longer videos can take a long time.
• AVI: MPEG-4 video with MP3 audio. FLV: FLV video with MP3 audio. WMV: WMV2 video with WMA v2 audio. OGV: Theora video with Vorbis audio. MPG: MPEG-2 video with MP2 audio.
• 3GP: MPEG-4 video with AAC audio, with the audio fixed at 8000 Hz mono, so sound quality drops noticeably.
• GIF and animated WEBP: both fixed at 10 frames per second, scaled to 480 pixels wide with proportional height, and silent.
• MP3, WAV (16-bit PCM), AAC/M4A, FLAC and OGG (Vorbis): the video is removed and only audio is kept.

Supported range and known limits

• There are no controls for quality, bitrate, resolution or frame rate; even the 10 fps and 480-pixel width for animations are fixed. The codecs and settings are those listed above. For fine control, use desktop FFmpeg.
• The single-threaded FFmpeg core is used, which is slow in a browser. Long or high-resolution videos take a long time and a lot of memory. The whole file is read into browser memory, so very large files may fail.
• The first use downloads about 25 to 30 MB of FFmpeg core files from a third-party CDN (unpkg), so you need a connection and some patience at first. It is not downloaded again while the page stays open.
• Whether the result plays in the preview depends on your browser. Formats such as AVI, WMV, FLV and MKV may not play in the in-page preview, though the downloaded file is still in that format and can be opened with a local player.
• The trim values are passed straight to FFmpeg. A badly formatted value usually makes the conversion fail, and the page only shows the generic failure message without a reason. Use a format like 00:00:05.
• One file per conversion; there is no batch mode. The AAC option produces an .m4a file.

FAQ: Why is the conversion so slow?

The work is done in your browser with WebAssembly, without hardware acceleration and without multiple threads, so it is far slower than desktop software. Longer and higher-resolution videos take longer, and WEBM (VP9) is typically the slowest. To speed things up, use the trim fields to select only the part you need, keep animations short, and use desktop software for long videos or large files.

FAQ: What if the converted file will not play?

First check whether your player supports that format and codec. Older formats such as AVI, WMV, FLV and 3GP are handled differently by phones and browsers, while MP4 with H.264 and AAC is usually the most compatible. Try converting to MP4, or use a local player that supports more formats. If the output is only a few KB or will not open at all, the conversion most likely went wrong, so try another format or a shorter section.

FAQ: Is my video uploaded?

The video itself is not uploaded. The file is read into browser memory and processed by FFmpeg running in the page, and the result is downloaded through a temporary local link. The only network activity is the one-time download of the FFmpeg core on first use, described in the privacy section below.

FAQ: Can I extract only the sound?

Yes. Choose MP3, WAV, AAC/M4A, FLAC or OGG as the target format. The video track is dropped, only audio is produced, and an audio player appears so you can listen to it. WAV and FLAC keep higher quality but make larger files, while MP3 and AAC are smaller.

Privacy and how files are processed

Reading, converting and producing the result all happen in your browser, and the video content is not sent to this site or any server. One thing to be open about: on the first conversion, the page downloads FFmpeg's core script and WebAssembly file from a third-party CDN (unpkg.com). That is a request to an outside server, which can see ordinary request details such as your IP address but not your video. The result exists only in the page's memory and is gone after you refresh or close the page.