Information Technology Reference
In-Depth Information
video conference systems for business use, by KDD, NTT and Mitsubishi etc., in
Japan. In the middle of 1980s, it became possible to simulate the video coding al-
gorithms more easily with improved workstation capability, and practical research
was greatly advanced. As it was at the dawn of a new age of digital communication
line based on Integrated Services Digital Network (ISDN), the development of the
products of pioneering video conference system was carried out. The CCITT (Con-
sultative Committee for International Telephone and Telegraph), now known as
ITU-T (International Telecommunication Union - Telecommunication sector), be-
gan to consider and discuss the needs of interconnectivity and interoperability for
video transmission assuming TV phone, video conference, remote surveillance, etc.
In 1990, CCITT has recommended H.261 for video coding scheme at the transmis-
sion rate of px64 Kbit/s (p=1, 2, ...) for the communication of video and audio on
ISDN [1]. In H.261, a hybrid coding system using the combination of motion com-
pensated prediction coding and transform coding was adopted, and many of the
current video coding systems are derived from the hybrid coding system from
H.261. In this period, VTR became more widespread in the home because of its
tendency of lower-pricing. Under such a situation, MPEG, which has been a work-
ing group under ISO/IEC, started the development of an international standard for
video coding that aimed at consumer appliances in 1988.
Since the 1980s, the history of video coding technology has been deeply related
to the international standardization. MPEG specifically aimed at the development
of audio and video coding methods for CD (Compact Disc) which began to spread
rapidly with the advent of digital music. MPEG-1 specified the coding of video
with up to about 1.5 Mbit/s; this standardization was completed in 1993 and was
adopted for video CD and CD karaoke [2].
Subsequently, MPEG-2 was standardized as MPEG-2/H.262 [3, 4] and aimed
at the coding of SDTV and HDTV; this standardization was completed through
cooperation between ISO/IEC and ITU-T in 1994. The standardization of MPEG-
2 triggered the roll-out of digital broadcasting. Video coding technology provided
a means to satisfy constraints on the communication bandwidth and storage capac-
ity for transmitting and storing video, respectively. Until MPEG-2 was standard-
ized, the video was always treated with lower resolution than standard television
broadcasting. However, with the advent of MPEG-2, video coding technology was
able to realize high quality video services. In 1995, NHK and Mitsubishi had
jointly developed an HDTV codec conforming to MPEG-2 specification, and con-
ducted a verification experiment on digital HDTV broadcasting, This became a
turning point to accelerate digital TV broadcasting. After then, MPEG-2 began to
be adopted as a video coding scheme for digital broadcasting in Japan, Europe and
the United States. HDTV digital broadcasting began to be a full-fledged service
world-widely in early 2000s, and the spread of LCD displays brought the realistic
video experience of 1920 scanning lines to home.
On the other hand, the combination of the Internet and PC had grown greatly as
a platform for multimedia services since Mosaic, which was an Internet browser,
