576i and 576p Systems
Interlaced Analog Composite Video
(B, D, G, H, I, N, NC) PAL are analog composite video signals that carry all timing and color information within a single signal. These analog interfaces use 625 lines per frame.
Interlaced Analog Component Video
Analog component signals are comprised of three signals, analog R′G′B′ or YPbPr. Referred to as 576i (since there are typically 576 active scan lines per frame and they are interlaced), the frame rate is usually 25 Hz for compatibility with PAL timing. The analog interface uses 625 lines per frame, with active video present on lines 23–310 and 336–623, as shown in Figure 3.14.
FIGURE 3.14. 576i Vertical Interval Timing.
For the 25 Hz frame rate, each scan line time (H) is 64 μs. Detailed horizontal timing is dependent on the specific video interface used, as discussed in Chapter 4.
Progressive Analog Component Video
Analog component signals are comprised of three signals, analog R′G′B′ or YPbPr. Referred to as 576p (since there are typically 576 active scan lines per frame and they are progressive), the frame rate is usually 50 Hz for compatibility with PAL timing. The analog interface uses 625 lines per frame, with active video present on lines 45–620, as shown in Figure 3.15.
FIGURE 3.15. 576p Vertical Interval Timing.
For the 50 Hz frame rate, each scan line time (H) is 32 μs. Detailed horizontal timing is dependent on the specific video interface used, as discussed in Chapter 4.
Interlaced Digital Component Video
BT.601 specifies the representation for 576i digital R′G′B′ or YCbCr video signals. Active resolutions defined within BT.601, their 1× Y and R′G′B′ sample rates (Fs), and frame rates, are:
| 960×576i | 18.0 MHz | 25 Hz |
| 720×576i | 13.5 MHz | 25 Hz |
Other common active resolutions, their 1× ?Y and R′G′B′ sample rates (Fs), and frame rates, are:
| 1024×576i | 19.67 MHz | 25 Hz |
| 768×576i | 14.75 MHz | 25 Hz |
| 704×576i | 13.50 MHz | 25 Hz |
| 544×576i | 10.12 MHz | 25 Hz |
| 480×576i | 9.000 MHz | 25 Hz |
1024×576i is a 16:9 square pixel format, while 768×576i is a 4:3 square pixel format. The 704×576i format is done by using the 720×576i format, and blanking the first eight and last eight samples each active scan line. Example relationships between the analog and digital signals are shown in Figures 3.16 through 3.19.
FIGURE 3.16. 576i Analog-Digital Relationship (4:3 Aspect Ratio, 25 Hz Frame Rate, 13.5 MHz Sample Clock).
FIGURE 3.17. 576i Analog-Digital Relationship (16:9 Aspect Ratio, 25 Hz Frame Rate, 18 MHz Sample Clock).
FIGURE 3.18. 576i Analog-Digital Relationship (4:3 Aspect Ratio, 25 Hz Frame Rate, 14.75 MHz Sample Clock).
FIGURE 3.19. 576i Analog-Digital Relationship (4:3 Aspect Ratio, 25 Hz Frame Rate, 10.125 MHz Sample Clock).
The H (horizontal blanking), V (vertical blanking), and F (field) signals are defined in Figure 3.20. The H, V, and F timing indicated is compatible with video compression standards rather than BT.656 discussed in Chapter 5.
FIGURE 3.20. 576i Digital Vertical Timing (576 Active Lines). F and V change state at the EAV sequence at the beginning of the digital line. Note that the digital line number changes state prior to the start of horizontal sync, as shown in Figures 4.16 through 4.19. IEC 61834-2, ITU-R BT.1618, and SMPTE 314M (DV formats) specify lines 23–310 and 335–622 for active video.
Progressive Digital Component Video
BT.1358 specifies the representation for 576p digital R′G′B′ or YCbCr signals. Active resolutions defined within BT.1358, their 1× Y and R′G′B′ sample rates (Fs), and frame rates, are:
| 960×576p | 36.0 MHz | 50 Hz |
| 720×576p | 27.0 MHz | 50 Hz |
Other common active resolutions, their 1× Y and R′G′B′ sample rates (Fs), and frame rates, are:
| 1024× 576p | 39.33 MHz | 50 Hz |
| 768×576p | 29.50 MHz | 50 Hz |
| 704×576p | 27.00 MHz | 50 Hz |
| 544×576p | 20.25 MHz | 50 Hz |
| 480×576p | 18.00 MHz | 50 Hz |
1024×576p is a 16:9 square pixel format, while 768×576p is a 4:3 square pixel format. The 704×576p format is done by using the 720×576p format, and blanking the first eight and last eight samples each active scan line. Example relationships between the analog and digital signals are shown in Figures 3.21 through 3.24.
FIGURE 3.21. 576p Analog-Digital Relationship (4:3 Aspect Ratio, 50 Hz Frame Rate, 27 MHz Sample Clock).
FIGURE 3.22. 576p Analog-Digital Relationship (16:9 Aspect Ratio, 50 Hz Frame Rate, 36 MHz Sample Clock).
FIGURE 3.23. 576p Analog-Digital Relationship (4:3 Aspect Ratio, 50 Hz Frame Rate, 29.5 MHz Sample Clock).
FIGURE 3.24. 576p Analog-Digital Relationship (4:3 Aspect Ratio, 50 Hz Frame Rate, 20.25 MHz Sample Clock).
The H (horizontal blanking), V (vertical blanking), and F (field) signals are defined in Figure 3.25. The H, V, and F timing indicated is compatible with video compression standards rather than BT.656 discussed in Chapter 5.
FIGURE 3.25. 576p Digital Vertical Timing (576 Active Lines). V changes state at the EAV sequence at the beginning of the digital line. Note that the digital line number changes state prior to the start of horizontal sync, as shown in Figures 3.21 through 3.24.
