gst-plugins-base Elements

audioconvert - Convert audio to different formats
audiotestsrc - Creates audio test signals of given frequency and volume
ffmpegcolorspace - Converts video from one colorspace to another
multifdsink - Send data to multiple filedescriptors
tcpserversink - Send data as a server over the network via TCP
theoraenc - encode raw YUV video to a theora stream
videotestsrc - Creates a test video stream
volume - Set volume on audio/raw streams
vorbisenc - Encodes audio in Vorbis format