Databases Reference
In-Depth Information
F I GU R E 19 . 15
Scanning pattern for the DCT coefficients of a field block.
When the Federal Communications Commission (FCC) requested proposals for the HDTV
standard, they received four proposals for digital HDTV from four consortia. After the evalu-
ation phase, the FCC declined to pick a winner among the four, and instead suggested that all
these consortia join forces and produce a single proposal. The resulting partnership had the
exalted title of the “Grand Alliance.” The Grand Alliance system used the
main
profile of the
MPEG-2 standard implemented at the
high
level.
19.10 ITU-T Recommendation H.263
The H.263 standard was developed to update the H.261 video conferencing standard with
the experience acquired in the development of the MPEG and H.262 algorithms. The initial
algorithm provided incremental improvement over H.261. After the development of the core
algorithm, several optional updates were proposed that significantly improved compression
performance. The standardwith these optional components is sometimes referred to as H
.
263
+
(or H.263
).
In the following sections we first describe the core algorithm and then describe some of the
options. The standard focuses on noninterlaced video. The different picture formats addressed
++
