FFmpeg is a very powerful product allowing to play, create or get information from supported multimedia files.
Nevertheless, a light tool allowing to probe audio/video codec information can be very useful.
FFprobe is the perfect candidate, based on FFmpeg functionalities, it gives quick information about video and audio streams.
If your GNU/Linux version does not provide it, you can compile it from source (see INSTALL file for requirements).
It may be needed to specify ffmpeg include directories for configure to work (it was my case under GNU/Linux Fedora 10):