I have some badly made WMV-files on my server that are huge (some GB) with just some picture slide-shows in it.
Is it possible to compress them on the console there on the debian server so I can download them easily after?
This depends on what you mean by compress. You can compress any file with plain, built in compression tools. For example, with
This will replace the video with a compressed version in the file
input.wmv.bz2. You will then need to uncompress the file after you transfer it.
If you want to put the video into some sort of compressed video format, you can use a tool like
ffmpeg. Thorough documentation is available at http://ffmpeg.org/ffmpeg.html and you may be limited in the formats that you can use out of the box, since Debian is rather strict in regards to its open source nature.
A simple example of converting a video with
ffmpeg would be this:
ffmpeg -i input.wmv output.mp4
This will convert your WMV file to an MP4 file. You can give it more options to tune the output if you need to further size down the video, although you are at risk of degrading the quality.