DigitalVideoAndHDTVAlgorithmsAndInterfaces.pdf

tri Trilevel pulse
BR Broad pulse
The vertical center of the picture
is located midway between lines
385 and 386.
Line number Contents
1–5 tri/BR (5 lines)
6 Blanking
7–25
(19 lines)
Blanking/Ancillary
26–745 Picture
(720 lines) [Clean aperture 702 lines]
746 –750
(5 lines)
Blanking
Table 46.2 1280×720 line assignment
A frame comprises a total of 750 horizontal raster lines
of equal duration, uniformly progressively scanned top
to bottom and left to right, numbered consecutively
starting at 1. Of the 750 total lines, 720 contain picture.
Table 46.2 above shows the assignment of line numbers
and their content.
For studio video, the tolerance on frame rate is
normally ±10 ppm. In practice the tolerance applies to
a master clock at a high frequency, but for purposes of
computation and standards writing it is convenient to
reference the tolerance to the frame rate.
At a digital interface, video information is identified by
a timing reference signal (TRS) conveyed across the
interface. (See Digital sync, TRS, ancillary data,
and interface, on page 389.) The last active line of
a frame is terminated by EAV where the V-bit becomes
asserted. That EAV marks the start of line 746; line 1 of
the next frame starts on the fifth following EAV.
Analog interfaces are discouraged for all but the three
highest-rate systems (720p60, 720p59.94, and
720p50). Analog signal timing is defined by the digital
standard; the digital sampling frequency defines reference
time intervals used to define analog timing.
548 DIGITAL VIDEO AND HDTV ALGORITHMS AND INTERFACES