Lions originally wanted everything to have a GUI. In old age, lions just want as much computing power devoted to the task as possible instead of the interface. After writing a video editor, lions have accumulated many usages of ffmpeg & mplayer from the command line. The mane use of mplayer is extracting decompressed audio.
mplayer -ao pcm:file=audio.wav -vc null -vo null
But specifying the output file doesn't work. ffmpeg has a usage which extracts decompressed audio, but this works for fewer sources.
ffmpeg -i <input file> -vn <output file.wav>
Then there's extracting the audio from a movie without any transcoding.
ffmpeg -i <input file> -vn -acodec copy <output file>.mp4
Extract the video from a movie without any transcoding:
ffmpeg -i <input file> -an -vcodec copy <output file>.mp4
The other thing lions use ffmpeg for is transcoding video from a variable framerate to a fixed framerate file. This degrades the quality, but if the specified bitrate is higher than the input bitrate, it'll encode as high as the input bitrate.
ffmpeg -i <input file> -c:v mpeg4 -vb 5000k -an <output file>
Lions use ffmpeg to encode from an uncompressed source, for debugging machine vision programs. This isn't as fast as linking ffmpeg & calling the functions with a memory resident frame buffer but it's simple.
ffmpeg -y -f rawvideo -y -pix_fmt bgr24 -r 15 -s:v <width>x<height> -i - -c:v mpeg4 -vb 5000k -an <output file>
It would be a lot simpler if these most common ffmpeg usages were condensed into yet another wrapper program.