[Tig] PAL HD

Dan C. Tatut dtatut
Sun May 7 19:52:33 BST 2006

Thanks to oktobor for supporting the TIG
Well, Rob you are right, TIG would definitely benefit from a more accessible explanation on HD but not only. I wish I had time to write some papers that would render all these concepts much more simple.

However there is one thing I want to say here (Rob will probably appreciate the digression of this).

Initially PAL and NTSC were designed around a simple thing: the variation of the electrical power in the US (60Hz, polarity changes 60 times per second) and Europe (50Hz, polarity changes 50 times per second). Back in the early days of video, systems were much simpler than now and have them based on the actual electrcal power polarity variation simplified lots of things.

Interlacing of pictures is also inherited from then. The available bandwidth at that time was not great enough to handle full pictures, so engineers chose a smart (???) way of displaying images by switching between odd and even lines when polarity changed. As you all know this opened the pandora's box and let tons of equipment be developed to manipulate the NTSC (US) and PAL(Europe) signals. 

As technology became more powerful, engineers thought about designing a new standard, the HD (or high definition). However for various reasons, HD has not been defined as a single new standard but rather as a set of standards. Why? Does one thing that engineers were so stupide to miss the opportunity of harmonization? No!

You have to bear in mind that behind all these nice TV signal transmission standards, there is money, and I mean BIG money. For more than 50 years, US commercial allies chose the NTSC transmission and Europe's commercial allies chose PAL transmission. At some point France attempted to impose its signal SECAM. SECAM (which has deisappeared from almost any country that used it) has been adopted by French close commercial allies such as African countries and Russia.

As I said before, HD coul have been progressive only and probably now we could all live without the bloody interlaced pictures. But NO WAY! Try to picture this: imagine how much money it would take to replace all the TV sets in the US with a new standard that has no relationship with what has been in use for more than five decades! It's immense. Also picture this: ask all the manufacturers of TV sets and broadcast equipment to drop all the product lines and change over night for a new standard. 

Makes sense from an engineering point of view, but definitely not from a commercial point of view. 

Because of this, HD is an actual set of signals with different properties aimed at facilitating the migration from SD to HD all over the world. These standards are designed to facilitate the technical migration but also the commercial migration. Backwards compatibility has been driven by BIG MONEY here, not engineers. It's probably one of the reasons why it took HD more than a decade to become a viable way for mastering and transimtting images.

Now this one is for Bob Friesenhahn: in my opinion, there is very little chance to have PAL-based countries adopt any of the ATSC standards, and that because of the reasons I mentioned above.

Best, Dan

Dan Tatut
CHROME Imaging
105 Rue de Lyon
CH-1203 Geneva

Phone: +41 22 807 23 60
Fax: +41 22 807 23 70
Mobile: +41 78 659 11 04
WWW: http://www.chrome-imaging.com

-----Original Message-----
From: Rob Lingelbach [mailto:rob at colorist.org]
Sent: dimanche, 7. mai 2006 19:52
Subject: Re: [Tig] PAL HD

Thanks to oktobor for supporting the TIG

On May 7, 2006, at 1:47 , Bob Friesenhahn wrote:

> In the US we use the ATSC standards, which encompass various facets  
> of delivering HD video.  Countries currently using PAL could chose  
> to use the ATSC standard, or they could use some subset of ATSC  
> standards along with COFDM to broadcast the signal.

I think it would be great if the acronyms that are more obscure to  
non-engineers were defined more often in postings.   Though top  
engineers are in the plurality of correspondents
here on the group (which has been an evolution, and has not always  
been the case) there are just as many colorists, assistants,  
managers, facility coordinators, and the like
for whom the technical language could be more accessible in  
postings.   Glossaries are cool but it's a lot easier just to add  
(parenthetically) a definition of the latest acronym.
(I count 5 with two repetitions in the above two sentences :] )

for the record:
COFDM = Coded Orthogonal Frequency Division Multiplexing    (which  
wins a prize for syllables!)
   reference:  http://www.digitalradiotech.co.uk/cofdm.htm
ATSC =  Advanced Television Systems Committee        (well hey this  
one should probably be pretty well-known by most of us now)
   reference:  http://www.atsc.org

PAL and HD shouldn't need explaining I imagine.

One reason I mention this is that the original question may have  
indicated that the questioner (whom I know :] ) may be more  
enlightened with a definition of (e.g.) COFDM
(which I had to look up to refresh my own memory).

just 2c worth of comment, etc.

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