DigitalVideoAndHDTVAlgorithmsAndInterfaces.pdf

Rabbani, Majid, and Paul W.
Jones, Digital Image Compression
Techniques (Bellingham, Wash.:
SPIE, 1991).
Motion-JPEG (M-JPEG)
Motion-JPEG (M-JPEG) refers to the use of a JPEG-like
algorithm to compress every picture in a sequence of
video fields or frames. I say “JPEG-like”: The algorithms
used have all of the general features of the algorithm
standardized by JPEG, including DCT, quantization, zigzag
scanning, and variable-length encoding. However,
ISO JPEG bitstreams are not typically produced, and
some systems add algorithmic features outside of the
JPEG standard. Various M-JPEG systems are widely used
in desktop video editing; however, there are no well
established standards, and compressed video files typically
cannot be interchanged between M-JPEG systems.
In studio applications, file interchange is a practical
necessity, and two approaches have emerged. Both are
functionally equivalent to M-JPEG, but have firm standards.
The first approach is DV compression, developed for
consumer digital recording on videotape, but now quite
widely used in desktop video editing. DV compression
is described in the following chapter.
The second approach is MPEG-2 video compression,
described in the succeeding chapter (starting on
page 473). MPEG-2 was developed to exploit interframe
coherence to achieve much higher compression
ratios than M-JPEG, and is intended mainly for video
distribution. However, the I-picture-only variant of
MPEG-2 (sometimes called I-frame-only) is functionally
equivalent to M-JPEG, and is being used for studio
editing.
A few studio DVTR formats, such as Digital Betacam
and HD-D5, use M-JPEG-style compression, but are not
intimately related to any of JPEG, DV or MPEG.
Further reading
Rabbani and Jones have written an excellent introduction
to the mathematics of still image compression.
460 DIGITAL VIDEO AND HDTV ALGORITHMS AND INTERFACES