ATSC broadcast may push over the air 1080p broadcast.

Joe_Cracker

The new digital TV broadcasting standard ATSC that is set to go into effect next year could eventully be broadcasting over the air 1080p. We went from Black and white, to color, to cable, to sattlelight, to HD.

Right now the maximum output signal for HD broadcasting is 1080i, meaning that if you own a 1080i set then you don't need anything else because your recieving the signal at it's fullest quality. Right now the only way you can get a 1080p broadcast is to use the PSF(Pogressive segemented frame) metiod. It allows 1080p on interlaced media that can only handle 1080p. That means if you own a 1080i set, you'll be viewing 1080p regardless. For those who own 1080p sets, you won't to rely on anymore de-interlacing.

If the PSF method can be used, why don't broadcasters use it?

rbinck

Where did you get this? Got Link?

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BobY

Since the ATSC standards don't support 1080p/60, they presumably would be talking about broadcasting 1080p/24 or 1080p/30, which would fit within the existing bandwidth of 1080i/30.

1080p/24 would be great for films and would even free up some bandwidth for the broadcasters. I can't imagine them producing programming in 1080p/30, as it's motion response would be inferior to either 720p/60 or 1080i/30.

Hopefully they wouldn't consider de-interlacing content sourced at 1080i/30 to 1080p/30--that would be ugly...

rbinck

Films could be sent at 1080p/30 with same motion response as 1080i/30, but why?

Assuming the TV tuners actually would handle 1080p/24 my question would be how would it be displayed? If it still used a 60 hz refresh, there would be no gain.

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BobY

Except the broadcasters would be left with extra bandwidth to make money on

The same caveat could be said about Blu-Ray and HD DVD players--if your display doesn't support 1080p/24, or it supports 1080p/24 but not a refresh rate that is a multiple of 24Hz, it doesn't get you anything. But more and more new HDTV's are going to be supporting that feature in the future.

Signals captured at 1080p/30 have half the motion update rate of signals captured at 1080i/30. A 1080p/30 signal updates frames 30 times per second, while a 1080i/30 signal updates fields 60 times per second--temporal resolution (i.e. motion response) is twice as good although spatial resolution at that rate is half as good.

rbinck

Yes a gain for broadcasters, but none for the user which I was saying to the OP. That post implied there would be some benifit to the viewer and I don't see it. That's why I asked for a link to try to see what was behind the post.

It is quite possible, even though ATSC tuners are supposed to support 1080/24p and 1080/30p, that many in use today do not. I don't think broadcasters will take that chance.

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BobY

Personally, I doubt that *any* of the ATSC tuners currently out there (at least in conjunction with their built-in MPEG2 decoders) can decode 1080p/24 or 1080p/anything. I really can't imagine a penny-pinching CE company bothering to provide compatibility with signals that aren't in use and weren't planned to be in use, even if they are in the ATSC spec.

I could be wrong, but I doubt it...

1080PsF

PsF... only means that it is recorded on tape progressive but the output is still interlaced. That is why the CRT monitors can handle it, if it were true progressive the CRT monitors would freak out. So there would be no difference to a signal that is film based, but if it were video based it would have jaggies.

BobY

The motion response of 1080PsF would be half that of 1080i in the same bandwidth--1080PsF/30 would capture 30 Frames-per-second, while 1080i/30 would capture 60 fields-per-second.

There is not enough bandwidth to transmit 1080p/60 or 1080PsF/60, so any signal captured at 1080PsF they could transmit would have inferior motion response compared to either 1080i/30 or 720p/60.

Films are already essentially transmitted as 1080PsF/30, as the modern, digital Telecine process is based on always extracting fields from the same film frame and repeating whole frames as necessary to pull down the film from 24Fps to 30Fps (i.e. 60 fields-per-second).

1080PsF

The Telecine 3:2 pulldown is not done in frames it is done in fields so there are still mixed frames.
There is no 1080PsF/60, it is 23.98, 24, 25, 29.97, & 30.

BobY

Yes, Telecine is still done in fields, but with current digital Telecine, the two video fields (which essentially create a video "frame") always come from the same frame of film, not like the mechanical Telecine process which periodically created new video "frames" by combining fields from different film frames--very bad if there was a cut or scene change in the film between the scan of the first field and the scan of the second.

That was all the result of moving the film through the scanner gate synchronized to the video scanner vertical sync rate. Since there was no real-time storage (the film itself was the "storage"), the fields came from whatever film frame happened to be in the gate at the time. Now they can keep the film frame in memory and derive the two fields from that to avoid the problem of scene changes between the first and second field.

At that point, the interlaced result is effectively PsF, as both fields of each video "frame" come from the same instant in time even though the are transmitted as two interlaced fields.

1080PsF

The telecine 3:2 pulldown takes a film frame and makes two fields of video from it, then the next frame of film makes three video fields, then the next frame of film makes two fields of video, and then the next frame of film makes three fields of video and so on and so on. Thus the third frame of video is a mixed frame from the second and third film frames and the fourth video frame is also a mixed frame from the third and fourth film frames. That is also how the video tape machines that record 23.98 make an NTSC signal.

So I don't understand what you are saying about no mixed frames.

BobY

That's the old system. I'm not talking about video tape.

AFAIK, Pull-down for HD is done digitally, so it never takes the odd video field from one film frame and the even video field from another film frame--it goes back to the film frame in the buffer memory and always takes both the odd and even fields from the same film frame.

It's not a real-time process, there is always several frames of delay between the film frame currently being scanned and the frame (fields) being output, or it's completely done as a post process after all the frames are in memory.

1080PsF

Every HD tape that I have sent out for broadcast here in the U.S. has been a 1080i/59.94 and it has a 3:2 pull-down in it (if it was film based) and it is done just like I wrote earlier. The 3:2 pull-down has been digital for the last 20 years, Rank Cintel made the digi-scan and that produced the 3:2 pull-down for telecine.

BTW it is real time. Both from telecine or from a video tape machine.

I've been running video for about 20 years and I have never seen the 3:2 done any other way than how I explained it (except for the new pro-sumor half-ass HD cameras). In those 20+ years I have been an on-line editor, telecine colorist, tape operator, and the manager of technical services. So if you could explain a little more about how the new digital 3:2 works or give me a link on where I could learn about I would really appreciate it.

rbinck

How is it done for 720p/60 broadcasts?

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