05-11-2016, 02:00 PM
(This post was last modified: 05-11-2016, 02:20 PM by Mike Watterson.)
(05-11-2016, 12:45 PM)ppppenguin Wrote: Yes. The hd specs are based on square pixels and the same pixel clock. All 1080 formats have different H blanking periods to make it all work.
Eh?
Most (if not all) Terrestrial HD isn't square (1440 x 1080 instead of 1920 x1080). Very much HD Satellite has changed from 1920 -> 1440 to match terrestrial output (either to save money or reduce quality).
Maybe I misunderstand what you are saying?
Sadly European HD was crippled to be based on the USA HD based on Japanese Hybrid Analogue 1125 line, to make the data rate about the same. Going from 480 line to 1080 line visible.
The original analogue 60 / 30i and 50 / 25i was two fold:
1) To avoid moving bar (from lighting in studio or PSU on TV set)
2) Interlace takes advantage of the fact we are more sensitive to resolution on a static image, it's a cunning analogue technique to halve the bandwidth.
Digital should have been 48 fps and 96 fps. Certainly progressive only. Interlace is EVIL for format conversions and rescaling and even for digital compression. It's not needed on Digital and a positive problem.
Whatever about 1080 lines in USA (2.25 vertical resolution) based on visible 1125 analogue, surely adopting PC 1200 visible lines would have made more sense in Europe? Or at least 1152 visible. (1296 is 576 x 2.25).
It's ironic that there are now more transmission standards and even HD formats (and very many SD formats) than Analogue had and some are not fit for purpose.
The move to higher resolutions is nonsensical unless you have a 72" screen. What is needed is progressive and higher frame rates. Even if you have a big screen, if the original is scanned from film or shot at 3840 x 2160, and reduced to 1920 x1080 (all Progressive), then it can actually be rescaled on reception for the people that do have larger than 56" screens, indeed up to 72"!
If the screen is 72" rather than 36" because it's 4m away instead of 2m away, then 1920x 1080 is fine, but progressive 96 / 100 / 120 fps will give far more improvement than 4K @ 50 or 60.
Now we have the stupidity that LCD screens on laptops are based on 1920 x 1080 60 fps progressive and we had better computer resolutions for documents, CAD etc 15 years ago!
