Information Technology Reference
In-Depth Information
Compression
rate
1/200
Next generation
video coding
Internet/Portable
Low quality
1/100
3G mobile
One-seg
Digital Broadcast
HDTV
MPEG-4 AVC
H.264
MPEG-4
HDTV
䋨IPTV䋩
1/50
MPEG-2
1/20
Satellite SDTV
DVD video
Portable
High quality
Blu-ray Disc
HDTV
Portable
High quality
1996
1998
2000
2002
2004
2006
2008
2010
䌾
Fig. 6
Improvement in Compression Ratio by MPEG
3 Video Coding Technology
3.1 The Shannon Theory and Video Coding Technology
Video coding aiming at digital information compression began its development
from the necessity of transmitting a vast quantity of digital video data through
communication line with narrow band. Therefore, it is possible to draw an analogy
between the information and telecommunication model of Shannon [12, 13] and
the composition of digital video coding transmission system (refer to Fig. 7). In
the sending side of a digital video transmission system, the analog video signal
acquired from a camera is digitally sampled and quantized. Format conversion is
performed using various filters and a sequence of digital images is generated [14].
Then, prediction, transform, quantization and entropy coding are applied to the
image sequence to produce a compressed bitstream (Source Coding) [15]. The
compressed bitstream then undergoes encryption, multiplexing, error detec-
tion/correction, modulation, etc., and is transmitted or recorded according to the
characteristic of a transmission line or a recording medium (Channel Coding). On
the other hand, in the receiving side, the video signal is reproduced by the inverse
operations performed in the sending side and the video is displayed on a screen.
