DigitalVideoAndHDTVAlgorithmsAndInterfaces.pdf

24
1. 001
30
1. 001
60
1. 001
≈
≈
≈
23. 976
29. 97
59. 94
System fS (MHz) STL 1080p60 148 2200
1080p59.94 148 ⁄1.001 2200
1080p50 148 2640
1080i30 74.25 2200
1080i29.97 74.25 ⁄1.001 2200
1080i25 74.25 2640
1080p30 74.25 2200
1080p29.97 74.25 ⁄1.001 2200
1080p25 74.25 2640
1080p24 74.25 2750
1080p23.976 74.25 ⁄1.001 2750
Table 47.1 1920×1080 scanning parameters are summarized.
Systems marked are beyond the limits of today’s technology.
Scanning
1920×1080 video represents stationary or moving twodimensional
images sampled temporally at a constant
rate of 24 ⁄1.001, 24, 25, 30 ⁄1.001, 30, 50, 60 ⁄1.001, or 60
frames per second. The base sampling rate is
74.25 MHz; this rate is modified by the ratio 1000 ⁄1001
for systems having noninteger frame rate, and doubled
to 148.5 MHz (possibly times 1000 ⁄1001) for progressive
systems at frame rates higher than 30 Hz. All of
these systems have 1125 total lines (LT ); the number of
samples per total line (STL ) is adapted to achieve the
desired frame rate. Table 47.1 above summarizes the
scanning parameters.
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.
A frame comprises a total of 1125 horizontal raster lines
of equal duration, uniformly scanned top to bottom and
left to right, numbered consecutively starting at 1. Of
the 1125 total lines, 1080 contain picture. Table 47.2
opposite indicates the assignment of line numbers and
their content.
558 DIGITAL VIDEO AND HDTV ALGORITHMS AND INTERFACES