A Little HD clarification before I jump into the brave new world

[caseyhayward]

I consider myself fairly familiar with HD (resolutions and Frame rates etc.)

but I remember hearing way back when that HD would mean the death of all of our NTSC woes. But I'm confused, are there both 60i and 50i versions of HD (NTSC and PAL)? Why is a modern technology even working with interlaced footage which was a workaround for 1950's limitations?

Will we just be dealing with the same image quality draw backs (never the same color) and system incompatibility that we've had since the 30's at a high resolution?

Ultimately, will there be NTSC HD and PAL HD?


Thanks in advance for shedding a little light on the subject.

 

[Spiff]

Why is a modern technology even working with interlaced footage which was a workaround for 1950's limitations?

This one's easy: bandwidth. Uncompressed HD signals are huge, and the majority of TV viewers are familiar with a 50-60 Hz temporal rate of information. As a result, the data needs to be heavily compressed - and one easy way to do this is with interlace. The perception of 60i and 60p is very similar... but the 1080 format also offers superior resolution for 30p and 24p framerates. Given the fact that big numbers sell, making an interlaced 1080 format, and touting higher quality than a 720p format at lower frame rates makes a compelling argument.

There seem to be claims that the majority of HD displays will handle both 50 Hz and 60 Hz signals. This could be the end of the discrepancy, but it seems obvious that for backward compatibility 50 Hz and 60 Hz signals will be around for quite a while.

-Spiff

 

[Barry_Green]

Yes, once upon a time we thought that HD would be the grand unifying standard.

(of course, now the ATSC supports six different HD broadcast formats in the US alone!)

There will be no NTSC-HD and NTSC-PAL; NTSC and PAL differ in many ways (color bandwidth, frame rate, scan lines, etc). HD is the same in both territories in almost all ways, however, there will still be different frame rates; NTSC countries will adopt 60hz (and 30hz and 24hz) broadcasting; PAL territories are more likely to adopt 50hz (and perhaps 25hz, and who knows -- 24hz?) broadcasting. But the frame size, the color sampling, the scan lines, all that stuff stays the same. The only difference is the frame rate.

So it's CLOSER, but not interchangeable.

As Spiff said, the frame rate differences exist primarily (apparently) for backward compatibility. Networks and broadcasters still have hundreds of millions of dollars of PAL and NTSC gear, so don't expect European territories to abandon 50-hz compatibility all of a sudden. Even in HD broadcasts in the US, they'll mix in up-rezzed SD with actual HD; a good example was the Kentucky Derby horse race, where nearly everything was shot SD and blown up (and looked awful, by the way), and when the actual race was run, that was shot in HD (and, also, looked pretty bad, because the MPEG compression got overloaded, so the entire lower half of the horses was a mosaic-y blur of compression artifacts and mosquito noise). But that's another discussion for another day...

Now, some sets (hopefully ALL sets!) will be able to display both signals (50hz and 60hz). But the broadcasters don't apparently have any plans to support broadcasting of the other territory's signal... so, you will still have incompatibility. A program shot in HD in Europe will be at 50hz, and when brought to the US for broadcast it will still have to undergo a 50Hz->60Hz interpolation.