Video Grayscale
Turn any colour video into black and white in one click and download it as an MP4. Runs in your browser, nothing is uploaded.
Everything runs in your browser. Your video is never uploaded, and nothing is stored.
How to use it
Drop a video onto the box, or tap it to pick one from your device. Press Make black and white. The colour is removed from every frame and you get an MP4 to download. A progress bar shows how far along it is. The sound is copied across untouched. The picture is re-encoded as H.264 at high quality, which is needed to remove the colour. The first run downloads a 31 MB engine. That happens once and is then cached, so every run after it starts immediately.
Questions
Is my video uploaded anywhere?
No. The whole thing runs inside your browser using a WebAssembly build of ffmpeg. Your video never leaves your device.
Why is the first run slow?
It has to fetch the 31 MB ffmpeg engine before it can do anything. The browser caches it, so every run after that starts straight away.
Does it change the sound?
No. The audio track is copied as it is. Only if it cannot be copied is it converted to AAC at 192 kbps.
Why does it take longer than some other tools?
Removing colour means every frame has to be redrawn and encoded again, so long or high resolution videos take more time, especially on phones.
Which files does it accept?
MP4, WebM, MKV, MOV and most other common formats. The result is always an MP4 that plays everywhere. Very large files are held in memory, so a phone may struggle past a gigabyte or so.