Packetized Elementary Stream

A Packetized Elementary Stream (PES) is the basic format by which streams of MPEG-1 or MPEG-2 audio or video, and other content such as subtitles, are stored within certain formats such as MPEG Program Stream.

A DVD has its content in a whole series of these. The VobSub program grabs the PES packets on a DVD that represent subtitles.

Links

 * Wikipedia article
 * PES header info
 * More PES info