Wow! Thanks Ron!
Now I understand! I know there is that MPEG2 header 1080/1088 indicator. And there is a small software that change a stream header from 1088 to 1080. But the header change tool never work for me on a HTPC. WinDVD/Nvidia MPEG2 decoder always show the bottom 8 gray lines while DScaler5 MPEG2 decoder never show the waste pixel.
So ALL MPEG2 1080i content are in fact in 1088i native format. Some with 1080i header and some with 1088i header. Some with the bottom 8 lines in black and some in gray/white/whatever.
I'd like to see these test "overscan" patterns:
- 1080i header, bottom 8 lines in black (already in the current test patterns)
- 1080i header, bottom 8 lines in gray
- 1088i header, bottom 8 lines in gray
- 1088i header, bottom 8 lines in black
Btw, is it possible to actual encode normal image in that 8 bottom lines? If possible, I'd like to see a "overscan" pattern which include the bottom 8 lines as part of the actually image, such as label the bottom 8 lines as 0 to -8 pixels!
Thanks in advance!