They have been available in ffmpeg since version 0.9, and we require 1.0 or higher.
We should look at height and width before ext_preference.
A workaround for video jumping back in time.
Player-url only needed for rmftp, not for regular URLs
Fixed code conventions (mainly adding two or more spaces before making an inline comment)
Implements #3638
720p @ 1000KB/s looks way better than 1080p @ 500KB/s