Each block is represented in the bitstream by VLE-

coded DCT coefficients – a differentially encoded DC

coefficient, and zero or more AC coefficients. Each

coded block’s data is terminated by a 4-bit end of block

(EOB).

Transport

Various syntax elements of MPEG video or audio are

serialized to form an elementary stream (ES). MPEG-2

defines a mechanism to divide an ES into packets,

forming a packetized elementary stream (PES). Each PES

pack header contains system-level clock information,

packet priority, packet sequence numbering, and

(optionally) encryption information. If an MPEG-2 PES

is stored in a file, the file conventionally has the exten-

sion m2v; however, a video PES can’t contain audio!

More commonly, though, MPEG-2 video and audio are

multiplexed, then stored or transported, using program

streams or transport streams, to be discussed in the

chapter MPEG-2 storage and transport, on page 555.

Further reading

Gibson, Jerry D., Toby Berger, Tom Lookabaugh, David Lind-

bergh, and Richard L. Baker (1998), Digital Compression for

Multimedia (San Francisco: Morgan Kaufmann). Looka-

baugh’s chapter provides an excellent 55-page description

of MPEG-2. His chapter also covers MPEG audio.

Haskell, Barry G., Atul Puri, and Arun N. Netravali (1997),

Digital Video: An Introduction to MPEG-2 (New York:

Chapman & Hall).This book fails to distinguish luminance

and luma; both are called luminance and given the symbol Y.

See Appendix A, YUV and luminance considered harmful, on

page 567 of the present book.

Mitchell, Joan L., William B. Pennebaker, Chad E. Fogg, and

Didier J. LeGall (1997), MPEG Video Compression Standard

(New York: Chapman & Hall).This book concentrates on

MPEG-1. Egregiously incorrect information appears

concerning chroma subsampling.

Symes, Peter (2003), Digital Video Compression (New York:

McGraw-Hill).

Watkinson, John (1999), MPEG-2 (Oxford: Focal Press).