There is a black gap at the top of image when using a external Signal Generator(NTSC-M) .
However,image produced by chips(adv7282m 480P) themselves is 720x480 size is normal.
Please refer to the attached file to get detailed description.
I hope to get your help,thanks!
Hi Yuanyuan Guo,
Do you see this issue with NTSC inputs but not PAL inputs ?
If so the issue is probably due to the output format from the ADV728x.
By default the ADV728x will output in ITU BT656-3 timing format (this is true for MIPI CSI-2 output models too).
If the receiver chip is expecting ITU BT656-4 format then this can result in 10 dark lines appearing at the top of the screen in NTSC mode. This is because ITU BT656-3 format has 10 more lines of vertical blanking than ITU BT656-4 format.
You can program the ADV728x to output in ITU BT656-4 format. Set User Map, register 0x04 bit to 1. This should solve your issue.
Senior Applications Engineer,
Digital Video Products Group,
Analog Devices Inc.