Buffer conversion not possible with node-fluent-ffmpeg?

Question

JavaScript

I want to convert a gif to webm without saving the gif on the server, i.e. from the buffer. I use multer and node-fluent-ffmpeg. The problem is that apparently it does not work. The
ffmpeg(req.file.buffer)
error is written

ffmpeg exited with code 1: Output #0, webm, to 'uploads/gifs/ddddd.webm':
Output file #0 does not contain any stream

It turns out that you must first save to a file, then this file will be read by ffmpeg and then converted? And why not from the buffer?