DigitalVideoAndHDTVAlgorithmsAndInterfaces.pdf

SMPTE RP 187, Center, Aspect
Ratio and Blanking of Video Images.
( )
STL - SEAV-0 + 05 . S
H AL - 1
STL
864 - 732 + 0. 5( 720 - 1)
=
864
983
=
1728
SMPTE RP 202, Video Alignment
for MPEG-2 Coding.
luminance, used in color science. Video encoding specifications
typically place no upper bound on luma bandwidth
(though transmission standards may).
Picture center, aspect ratio, and blanking
The center of the picture is located midway between
the central pair of the 720 active samples of Rec. 601,
at the fraction 983 ⁄1728 between 0H instants.
Concerning the vertical center, see Table 43.1, on
page 520.
Aspect ratio is defined as 4:3 with respect to a clean
aperture pixel array, 690 samples wide at sampling rate
of 13.5 MHz, and 566 lines high. Blanking transitions
should not intrude into the clean aperture.
In widescreen 576i with luma sampled at 18 MHz,
aspect ratio is defined to be 16:9 with respect to
a clean aperture pixel array, 920 samples wide.
In the composite and analog domains, video information
on the left-hand halfline of line 623 terminates
30.350±0.1 µs after 0 H . Video information on the righthand
halfline of line 23 commences 42.500±0.1 µs after
0 H.
No studio standard addresses square sampling of 576i
video. I recommend using a sample rate of 944f H , that
is, 14.75 MHz. I recommend using 768 active samples,
centered as mentioned above.
When MPEG-2 with 576 or 608 image rows is used in
the studio, the bottom image row corresponds to
line 623 (as indicated in Table 43.1). The bottom lefthand
halfline (on line 623) is among the coded image
rows. The right-hand half of this line will be blank when
presented to the MPEG encoder; upon decoding, it may
contain artifacts. Unfortunately, 576i DV systems digitize
a range one image row up from this.
Component digital 4:2:2 interface
The CB and CR color difference components of digital
video are formed by scaling B’-Y’ and R’-Y’ components,
as described in CBCR components for SDTV on
CHAPTER 43 576 i COMPONENT VIDEO 525