libavutil is a library containing functions for simplifying programming, including random number generators, data structures, mathematics routines, core multimedia utilities, and much more.
libavcodec is a library containing decoders and encoders for audio/video codecs.
libavformat is a library containing demuxers and muxers for multimedia container formats.
libavdevice is a library containing input and output devices for grabbing from and rendering to many common multimedia input/output software frameworks, including Video4Linux, Video4Linux2, VfW, and ALSA.
libavfilter is a library containing media filters.
libswscale is a library performing highly optimized image scaling and color space/pixel format conversion operations.
libswresample is a library performing highly optimized audio resampling, rematrixing and sample format conversion operations.