BRev Video & audio toolkit — free & private
Compress and convert video (MP4, WebM, GIF), trim a clip, extract the audio or mute it — with ffmpeg running in your browser: no upload, no watermark.
Everything runs in your browser with ffmpeg — nothing is uploaded. Short clips work best: it runs on a single thread, and it can use at most 2 GB of memory, so a very large file may not fit.
This toolkit runs ffmpeg, compiled to WebAssembly (ffmpeg.wasm), inside your browser tab, so the video you choose is processed on your device and never sent anywhere. The engine is served from this site and downloads the first time you press Run: a 32 MB WebAssembly file that arrives compressed at roughly 10 MB, which later runs in the same tab reuse. Pick one operation at a time. Compress and To MP4 re-encode to H.264 video with AAC audio, To WebM re-encodes to VP8 with Vorbis audio, and all three share a quality slider from CRF 18 to 40. To GIF lets you set 5–24 frames per second and a width from 160 to 800 pixels. Trim / cut copies the streams without re-encoding, Extract audio saves MP3 at 192 kb/s or 16-bit WAV, and Mute drops the audio track. Optional Start and End times apply to every operation. This build of ffmpeg is single-threaded, so short clips are quickest: a minute of video can take several minutes to encode.
What you can do
- Seven operations, one per run: Compress, To MP4, To WebM, To GIF, Trim / cut, Extract audio and Mute
- Compress and To MP4 write H.264 (libx264, veryfast preset) with AAC audio; Compress sets the audio to 128 kb/s
- To WebM writes VP8 video with a 1 Mb/s bitrate setting and Vorbis audio
- “Quality · CRF” slider from 18 to 40 (default 28) for Compress, To MP4 and To WebM; lower is better quality and a bigger file
- To GIF: 5–24 fps (default 12) and a width of 160–800 px in 20 px steps (default 480), height kept in proportion, looping
- Trim / cut and Mute copy the streams without re-encoding and keep the file's own container (MP4, MOV, M4V, MKV or WebM); Extract audio saves MP3 at 192 kb/s or 16-bit WAV
- Optional Start and End times (such as 0:05 and 0:20) work with every operation, and no watermark is added
How to use video & audio converter
- “Drop a video or audio file” or click “Choose a file”Drag a file onto the drop area or click to pick one; the picker takes any video or audio type. Nothing is processed until you press Run.
- Choose an operation under “What do you want to do?”Pick Compress, To MP4, To WebM, To GIF, Trim / cut, Extract audio or Mute. The settings below change to match the operation.
- Set “Quality · CRF”, “Start” and “End”Move the CRF slider (18–40, lower is better quality and a bigger file), or set the GIF frame rate and width, or MP3 or WAV. Start and End take times such as 0:05 and 0:20; leave them blank to cover the whole file.
- Press “Run”The first run downloads the ffmpeg engine, then a bar shows the encoding percentage. It runs entirely in this tab, so the page must stay open.
- Click “Download”The result appears with a player and its size before and after. Download saves it as your file's name with -brev and the new extension.
FAQ
Is my video uploaded to a server?
No. The file is read into the tab and handed to ffmpeg, which runs as WebAssembly in a Web Worker, and the result stays in the page until you click Download. The only extra download is the ffmpeg engine itself, served from this site on your first run; no part of your file is sent anywhere.
How large a video can it handle?
The tool sets no size or length cap, but everything happens in this one tab: the whole file is read into memory, ffmpeg's WebAssembly memory tops out at 2 GB, and this build encodes on a single thread, so a minute of video can take several minutes. When a file is too much, the tool says it “may be an unsupported format or too large for the browser to handle” and suggests a shorter clip. Setting Start and End encodes only that section.
Can I convert MOV to MP4?
Yes. Choose To MP4 and the video is re-encoded to H.264 with AAC audio. Trim / cut is not a shortcut to MP4: it copies the streams without re-encoding and keeps the container, so a MOV comes out as a MOV.
Why is my compressed video bigger than the original?
Compress aims for a quality level (the CRF value), not a file size, so a clip that was already tightly encoded can come out larger. The result says so with a “% larger” label instead of hiding it. Move the Quality slider towards 40, where quality drops and the file shrinks, and run again, or cut the clip down with Start and End.
How do I turn a video into a GIF?
Choose To GIF, set Start and End around the moment you want, then pick a frame rate (5–24 fps) and a width (160–800 px); the height follows the original's proportions and the GIF loops. The GIF is always scaled to the width you choose, even when the source is narrower, and fewer frames give a much smaller file, so keep the clip short.
Does Trim / cut lose quality?
No: Trim / cut copies the existing video and audio streams between your Start and End times without re-encoding, which is why it is fast, and it keeps the file's own container, so a WebM made by this tool stays a WebM and a MOV stays a MOV; Mute works the same way. A file in any other container is written as MP4, which cannot carry every codec; if that run fails, use To MP4 or To WebM with Start and End instead.
Can I extract the audio from a video as MP3?
Yes. Extract audio drops the video and saves MP3 at 192 kb/s or uncompressed 16-bit WAV. It accepts audio files as well, so it also turns an M4A or MP3 into WAV, or an M4A into MP3. If the video has no audio track, the run stops with a message saying the file may have none.