ffmpeg

The command ffmpeg is used to call a very fast video and audio converter that can also grab from a live audio/video source. It can also convert between arbitrary sample rates and resize video on the fly with a high quality poly-phase filter.

The following code block provides an example of executing the command. 
ffmpeg -i input.avi -b:v 64k -bufsize 64k -vcodec h264 output.avi
The above transcoding process in ffmpeg for each output can be described by the following diagram.
Figure 1. ffmpeg Transcoding Process