ATSC Compression Formats
60I, 30P, 24P
60P, 30P, 24P
16:9 and 4:3
60P, 60I, 30P, 24P
60P, 60I, 30P, 24P
Source: Ref. 18, Table 5.1. (Reprinted with permission.)
Video preprocessing converts the analog input signals to digital samples in such a
form needed for later compression. The analog input signals are red (R), green (G), and
Table 16.4 lists the compression formats covered by the ATSC standard. The following
explains some of the items in the table. Vertical lines refers to the number of active lines
in the picture. Pixels are the number of pixels during the active line. Aspect ratio, of
course, refers to the picture aspect ratio. Picture rate gives the number of frames or
fields per second. Regarding picture rate values, P refers to progressive scanning and I
refers to interlaced scanning. It should be noted that both the 60.00-Hz and 59.95 (i.e.,
× 1000/1001)-Hz picture rates are allowed. Dual rates are permitted at 30 Hz and
. Three active line formats are considered: 1080, 720, and 483. Table 16.5
summarizes the sampling rates.
For the 480-line format, there may be 704 or 640 pixels in an active line. If the input
is based on ITU-R Rec. BT 601-4 (Ref. 19), it will have 483 active lines with 720 pixels
in each active line. Only 480 of the 483 active lines are used for encoding. Only 704
of the 720 pixels are used for encoding: the first eight and the last eight are dropped.
The 480-line, 640-pixel format corresponds only to the IBM VGA graphics format and
may be used with ITU-R Rec. BT 601-4 (Ref. 19) sources by employing appropriate
Sampling precision is based on the 8-bit sample.
Colorimetry means the combination of color primaries, transfer characteristics, and
matrix coefficients. The standard accepts colorimetry that conforms to SMPTE.
inputs corresponding to ITU-R Rec. BT 601-4 may have SMPTE 274 M or 170 M col-
The input video consists of the RGB components that are matrixed into luminance
(Y) and chrominance (Cb and Cr) components using a linear transformation by means
of a 3
× 3 matrix. Of course, the luminance carries picture intensity information (black-
and-white) and the chrominance components contain the color. There is a high degree of
correlation of the original RGB components, whereas the resulting Y, Cb, and Cr have
less correlation and can be coded efficiently.
Sampling Rate Summary
480 line (704 pixels)
59.94-Hz field rate
fps stands for frames per second.
SMPTE stands for Society of Motion Picture and Television Engineers.