Understanding OTA DTV Broadcasting Technology in Canada - Page 6 - Canadian TV, Computing and Home Theatre Forums

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post #76 of 90 (permalink) Old 2009-03-05, 03:00 PM Thread Starter
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This thread is meant to be a more technical one, so recent posts regarding the current and future state of Canadian OTA broadcasting have been moved into their own thread:

Current and Future State of Canada's OTA Broadcasters

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post #77 of 90 (permalink) Old 2009-03-05, 07:26 PM
 
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It is interesting that you all understand the DOC has protected a bunch of freqs for OTA stations that are not likely to be built.
Why would the DOC "reserve" station on behalf of the CRTC? The CRTC is responsible for ensuring cancon rules are enforced and respected as well as access to "foreign" programming restricted. The DOC along with Industry Canada allocates the channel frequencies based on radiation footprint and interference patterns with other channels in cooperation with the FCC along border areas. Are you saying that there is collusion between government agencies to restrict access to some of the American channels along border regions?
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post #78 of 90 (permalink) Old 2009-03-05, 10:47 PM
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The DOC along with Industry Canada
AFAIK, DOC == Industry Canada. I think the DOC refers to the former Department of Communications, which is now part of the Depertment of Industry (Industry Canada).

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Are you saying that there is collusion between government agencies to restrict access to some of the American channels along border regions?
I think FraserR probably feels that way, but its probably an artifact of protecting potential Canadian interests. Don't forget that across national borders, the number of channels to protect becomes much greater, because the borders do not occur on the natural boundaries between broadcast areas, and all of a sudden, you need to have many more signals co-existing to be able to supply 5 or 10 or 15 channels per market twice over.
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post #79 of 90 (permalink) Old 2009-03-06, 12:36 PM
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Originally Posted by tvlurker View Post
I think FraserR probably feels that way, but its probably an artifact of protecting potential Canadian interests.
Kind of like the way people at CBC often feel that Bell Expressview intentionally degrades CBC's HD signal to make it look worse than CTV or TSN. This likely isn't true and is likely the result of other technical issues from the signal being down converted it to 720p, but it makes a great conspiracy theory.
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post #80 of 90 (permalink) Old 2009-03-24, 07:25 PM
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Not sure if this is the right thread, but I'll pose the question anyway.

Why are broadcasters using 1080i as opposed to 1080p?
In this day and age, isn't interlaced video kind of.. useless?
It had it's uses in analogue, but why digital? All the digital display devices use progressive to display pictures, no more CRT's doing so)

If I'm not mistaken, the video I've recorded and processed is 60 half-frames interlaced to 30.
Why not just do 1080p30 instead of 1080i60?

720p stations send 60 progressive frames at 1280x720
Half the framerate and double the res and you're at 1080p30
Since it's a little bit over double the res, even 1080p24 is feasible.

So, are there any reasons to use interlaced over progressive? (aside from "Because we want to", of course )
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post #81 of 90 (permalink) Old 2009-03-24, 07:30 PM Thread Starter
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The ATSC adopted 1080p as one of the many HD standards for DTV but when things were coming together in the late 1990s the reality of 1080p was quite a ways off.

There's nothing stopping a broadcaster from using it though, so I'd be interested in hearing the reasons against it being used.

My first question is what is the bandwidth difference between OTA HD in 1080i and 1080p.
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post #82 of 90 (permalink) Old 2009-03-24, 11:15 PM
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Well, my thinking is that, in theory, there should be no net difference, as you're trading 60 half-frames (interlaced into 30) to just 30 regular frames.
Still the same amount of data transferred in one second, so it should still have the same bitrate.
(30 frames x 1920x1080 = 62208000 pixels, 60 frames x 1920x 540 = 62208000 pixels)
The only difference should be in overhead and such, as the MPEG2 compression should be identical as the end frames are (supposed to be) identical
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post #83 of 90 (permalink) Old 2009-03-25, 08:42 AM
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Originally Posted by recneps77 View Post
The only difference should be in overhead and such, as the MPEG2 compression should be identical as the end frames are (supposed to be) identical
If anything, the MPEG2 compression should be slightly better with 1080p30 than 1080i as adjacent pixels are more likely to be similar than alternate pixels.
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post #84 of 90 (permalink) Old 2009-03-30, 01:03 PM
 
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Why are broadcasters using 1080i as opposed to 1080p?If I'm not mistaken, the video I've recorded and processed is 60 half-frames interlaced to 30.Why not just do 1080p30 instead of 1080i60?
First, there are two ways of making 60i. The first is to capture at 30p and send the odd lines followed by the even lines, the second is to capture at 60p and send just the odd lines from one frame, and just the even lines from the other. The latter would be "true 1080i", and if sent at 30p would not look as good as 1080i.

Second, remember that development of ATSC was started back in 1982, and even the top of the line CRTs couldn't display 1080 lines, so 1080i (effectively 540p) was much more reasonable. Flat panel displays were too small to consider.

Finally, both 1080i and 720p down-convert to 480i letterbox very easily.
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post #85 of 90 (permalink) Old 2013-08-15, 08:11 PM
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OK Now it is 4+ years on since the above post, and many many more people enjoy HDTV sets.

Has there been any change in transmitting bandwidth/resolution?

Is OTA in Canada 1080i or 1080p?

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post #86 of 90 (permalink) Old 2013-08-15, 08:46 PM
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you had to open the door...
1080i or 720p depending on the network's preference.
there is no 1080p anywhere OTA.

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post #87 of 90 (permalink) Old 2013-08-15, 08:57 PM
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Also some 480i....

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post #88 of 90 (permalink) Old 2013-08-15, 09:42 PM
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The only reasonable way to get 1080p OTA would be to use H.264 compression, but AFAIK, no TVs or STBs support H.264, so that would mean everyone replacing their equipment, so that isn't going to happen any time soon, if ever.

Link to my TVFool results is in my profile Homepage URL. I suggest others do the same.
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post #89 of 90 (permalink) Old 2013-08-16, 08:13 AM
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Tivo Premiere could theoretically support h.264 OTA. I think it does for cable, so easily could with a software update.

The Series 3 models could with a software update, but are finished for that.

Any PC DVR theoreticallt can, since the tuner just pipes received data to the HDD, and plays that out media decoder hardware or software.

I am not sure about smart TVs, maybe they can with a firmware update.
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post #90 of 90 (permalink) Old 2013-08-16, 09:57 AM
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I agree that some TiVos and most HTPC software could easily do H.264; however, I suspect only a small percentage of the market use these devices 100% of the time.

As for smart TVs, if they support H.264, they might be upgradeable, but then you are at the mercy of the OEM to actually provide the update. Most OEMs would rather sell new TVs than provide a free software update to add a feature that it wasn't advertised to have.

Having said that, considering the primary lobbyists for the transition to HD were television manufacturers to sell more TVs, they may like the idea of selling more.

Link to my TVFool results is in my profile Homepage URL. I suggest others do the same.
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