zombie said:
By using simple math 1080i to 1080p should double the required bandwith (double the pixels per frame, instead of 540 lines every frame youd have 1080 lines per frame)...
They are transmitting the same number of full frames. The three highest HDTV levels are:
1080/24p (x1920, Square or 16:9)
1080/30p (x1920, Square or 16:9)
1080/30i (x1920, Square or 16:9) = 1080i HDTV
These three are 2,073,600 pixels per frame (24p would be slighly lower bandwidth with the same compression due to less frames)
The next highest HDTV levels are (921,600 pixels):
720/24p (x1280, Square or 16:9)
720/30p (x1280, Square or 16:9)
720/60p (x1280, Square or 16:9)
24p would have the lowest bandwidth requirement moving up to 60p (60 full frames per second compared to 30 full frames in 30p or 30i formats).
The remainder of the 18 ATSC formats are not HD. ALL ATSC tuners MUST be able to tune ALL 18 formats. No ATSC TV is required to display *in* HD.
Monitors must be able to display 810i or 540p in the 16:9 viewable area to be defined as HD. Monitors less than 480p or NTSC are defined as SD. The middle ground is ED.
I'd like to see movies move to 1080/24p or 720/24p - primary movie channels in 1080 and additional channels in 720/24p or 480/24p. The 20% savings in frames can go toward decreasing the compression needed.
Voom has a 25% reduction by using 1440 width and DirecTV has 33% by using 1280. Going to 24p is a good way of saving 20% without losing a pixel.
JL