为了处理non-square pixels的图像,一种方法是720*59/54=768,把720像素转为768像素,
480i Non-Square Sampling 720 x 486 | 576i Non-Square Sampling 720 x 576 | |
---|---|---|
↓ scale horizontally by 10/11 ↓ 654 6/11 x 486 ↓ crop to 640 ↓ | ↓ scale horizontally by 59/54 ↓ 786 2/3 x 576 ↓ crop to 768 ↓ | |
640 x 486 480i Square Sampling | 768 x 576 576i Square Sampling |
还有就是采样是直接采用14.75MHz,ADV7179就可以直接解决这个问题。也是困惑了我半天的SQUARE PIXEL MODE
SQUARE PIXEL MODE :
The ADV7174/ADV7179 can be used to operate in square pixel mode. For NTSC operation, an input clock of 24.5454 MHz is required. Alternatively, for PAL operation, an input clock of 29.5 MHz is required. The internal timing logic adjusts accord-ingly for square pixel mode peration.
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