Game Development Reference
In-Depth Information
Table 2.1
NTSC/PAL/SECAM video formats
NTSC
PAL
SECAM
Lines/fields
525/60
625/50
625/50
Horizontal frequency
15.734kHz
15.625kHz
15.625kHz
Vertical frequency
59.939Hz
50Hz
50Hz
Color subcarrier frequency
3.58MHz
4.43MHz
4.25MHz
Video bandwidth
4.2MHz
5.0MHz
5.0MHz
Fig. 2.5
Interlace video scan
Fig. 2.6
Illustration of timing signal of scan line
video display without consuming extra bandwidth. An example of interlaced video is
shown in Fig.
2.5
, where the line 1, 3,
...
, will be scanned, transmitted and displayed
first, then line 2, 4,
, are scanned in the second round. Between the two scan lines,
there is an interval called horizontal retrace, which consists of front porch, sync,
and back porch, as shown in Fig.
2.6
. The front porch is between the end of each
transmitted line of picture and the leading edge of the next line sync pulse, which
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