High Quality Content by WIKIPEDIA articles! Packetized Elementary Stream (PES) is a specification in the MPEG-2 Part 1 (Systems) (ISO/IEC 13818-1) and ITU-T H.222.0 that defines carrying of elementary streams in packets within MPEG program stream and MPEG transport stream. The elementary stream is packetized by encapsulating sequential data bytes from the elementary stream inside PES packet headers.