Video Codecs and Playback

Video formats and support can be confusing. This section will describe some of the core topics of discussion related to video.

Codec: A codec is a computer program capable of encoding and/or decoding a digital data stream or signal. (Wikipedia Definition) Examples: DIVX, XVID, H264, VC1, MPEG2 are all Video Codecs. AC3, AAC, MP3, DTS are all Audio Codecs.

Container: A file wrapper that "contains" various codec streams into a single file. Examples: .WMV, .AVI, .MP4, .TS, .M2TS, .MKV, .WTV, .DVR-MS are all Video File containers that can contain certain combinations of Video AND Audio streams within a single file.

Transcoding: The process of taking a media file and converting it from one set of container/codecs to another. Example: Taking a .VOB file that has MPEG2 audio & video and converting it into a .AVI file that use h264 video & AC3 audio.

Muxing: The process of taking individual audio and video stream files and putting them succinctly into a single container file. DeMuxing: The Reverse. Taking a single media file and pulling the individual streams out into their own separate raw stream files. Example: Movie.AVI made up of h264/ac3 will be demuxed into two files-- a Movie.h264 video-only file, and a Move.ac3 audio-only file.