[John Mason]

Guess I'm just fuzzy on broadcast terminology. Several times in a speech last year, CBS's HDTV-pioneer, J.A. Flaherty, uses the term 1080 I&P, referring to ongoing broadcasts. Assume this means 1080 interlace and progressive. For example, (about half way down this speech) he said: "...last September CBS began transmitting 14 1/2 hours-per-week of prime time programming in 1080 I&P high definition along with "specials", movies, and major sporting events...." Two paragraphs later he cites over 120 hours per week from other sources using the 1080 I&P HDTV format. What does this mean?


While on this topic, does anyone know whether CBS (or anyone) is broadcasting in 'full' 1080i, meaning 1080iX1920 and not 1080iX

 

[David McRoy]

John, on the production side of the industry a lot of stuff is being shot in 1080/24p with more likely in the future. Also, 1080p/60 is in the ATSC table of transmission formats because it is thought that it may become possible to distribute in that format at some point in the future, if only by some means other than over-the-air in a 6 MHz channel (which is impossible, at least for now.)


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HiDefDave


[This message has been edited by David McRoy (edited 08-10-2001).]

 

[Abdul Jalib]

CBS is broadcasting the full 1920x1080i. This was mentioned in some press releases.


A web search suggests that the only person who has ever used this "1080 I&P" term is CBS's J.A. Flaherty, so he must mean "1080i and 1080p." My understanding is that 1080p is sometimes used for HDTV master tapes, with the main advantage being that it can be converted to 480p, 720p, or 1080i without scaling artifacts.



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Abdul
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[David McRoy]

I recall an interview with CBS Engineering honcho Bob Seidel in which he was asked, in part, a series of quick one-word questions to respond to. His response to "720p?" was "1080p."


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HiDefDave

 

[BobRoss]

Quote:

Originally posted by John Mason: ..... Assume this means 1080 interlace and progressive. ........

Yes


-=-=-=-=-=-=-=-=-=-=-

While on this topic, does anyone know whether CBS (or anyone) is broadcasting in 'full' 1080i, meaning 1080iX1920 and not 1080iX<1440 due to the horizontal resolution restrictions of widely used Sony HDCAM equipment? (BTW, doesn't Panasonic, maker of full-1080X1920 equipment, sponsor CBS programs?) If so, what programs are full 1080i? Think it would be interesting to know, assuming the ATSC folks are correct here about receivers filtering off some 20% of HDTV horizontal resolution, whether we're viewing 1440 less 20 percent or 1920 less 20 percent. Lots of other threads debate whether displays can even resolve 1920 - 20% = ~1540, and MPEG-2 encoding constantly varies picture details, but that seems even more academic if no broadcaster is delivering 1080iX1920 programming. -- John

-=-=-=-=-=-=-=-=-=-


The CBS delivery specification for shows delivered to us - requires a Panasonic HD D5 tape. This format is a full bandwidth HDTV format.


The answer to which shows are "full" 1920X1080 is very complicated. If you start with film which is capable of full HDTV - the first thing a director may do is put a filter on the camera to soften the image. You then transfer the film to the HD D5 tape and yes it's full 1920X1080 but the image is soft.....


1920 X 1080 i is a scanning format, it is not a picture quality statment. I do know for a fact that some of our shows, although delivered on HDD5 have passed though a generation or two of Sony HDCam. Just because it has been through a pass of HDCam does not mean the picture quality will not be up to snuff. Sony spent a great deal of time selecting the filters to provide the best picture quality for the bandwidth available.


BTW when we are doing live sports your looking at full bandwidth 1080i - we do not filter it in the truck or in the encoders.


Also there are professional monitors that can display the full bandwidth of 1080i. You can see the difference between material live from a camera, HDCam and DVCPro HD. The difference is NOT that great, it only becomes a factor during the production process with multiple generations.


Bob



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CBS New York

[email protected]


[This message has been edited by BobRoss (edited 08-10-2001).]


[This message has been edited by BobRoss (edited 08-10-2001).]

 

[John Mason]

Thanks for clearing things up, as much as possible, Bob. Figured it could get complicated rapidly with so many sources in the loop. But there's a lot of discussion on the net, as you know, about the preponderance of 1440-limited HDTV. Found it hard to believe, considering the vast differences I see with some programming, that CBS live HDTV wasn't full 1080i. -- John


[This message has been edited by John Mason (edited 08-10-2001).]

 

[BobRoss]

Hi John,


The bottom line -


At this time the HDTV quality variations you see are much greater than the 1440 sample of HDCam.


It's something else being tweaked.


Bob


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CBS New York

[email protected]

 

[Glimmie]

Bob, you may or may not be aware that starting this season the shows from Laser Pacific are being kept in SDTI for the entire assembly process. This saves at least two compression / decompression cycles. The assembly being done with the PVS supercomputer.


aka Glimmie

Manager, Systems Engineering

Laser Pacific Media Corp.

 

[FBT]

Bob, I was under the impression that HDCAM supported the full 1080x1920 HD spec and was wondering if you are actually saying that all HDCAM gear only operates at a horizontal resolution of 1440 or just some? If so is this an intentional pixel resolution drop or a result of the compression?


Additionally if this is the case why would Sony

a)so blatantly leave the market for Panasonic to do as it pleases and

b)put 1920 line CCDs in their cameras?


Additionally, how academic is this, considering the high levels of MPEG-2 Compression that this signal will be obliterated by? (I realize this depends on the actual content of the video but, still)


------------------
Christopher Spalding
Genius, excellent and generally gifted person.

 

[Rick_R]

Since the HDCams are 1080/24p which is converted to 1080/60i for transmission (actually 1080/48i as the ATSC standard says don't transmit frames that contain no information). Some TVs (Toshiba?) convert the 1080/60i back to 1080/24p for display. Therefore it may make no sense to transmit it in 1080/60i. I heard a rumor on another thread that CBS was considering transmission in 1080/24p, which is one of the 18 ATSC formats.


Rick R

 

[Glimmie]

Mike; no where did I claim this process was superior to competing facilities. It was just an FYI to Bob Ross and other interested members of a new process for HD 24P production. I did mention it saves two at least compression cycles and you even correctly indicated the HDCAM or HDD5 compression is not lossless.


As this is 99% a consumer hobby forum with very few broadcasters and next to no producers as members, I don't see even if I was advertising, what I would exepct to gain. My intent was technical information, nothing else.


As a second reply to this thread, these issues of pixel count and compression are irrelevant by the time the show comes off a DBS dish or OTA at 160:1 compression ratios.


As for 1080P/24 transmission, I don't see that happening anytime soon. There are too many problems with broadcast automation systems and monitorong system for a typical station or network to have a 24P plant. It is feasible to pull the 3/2 out in the MPEG encoder and let the STB put it back. I'm not sure if current models can do this. The NDS unit we have does not.

 

[Kelvin Colorspace]

Unless I am mistaken, there are no HD cameras that currently employ a CCD with true 1920x1080 resolution. The Sony HDCam system sub-samples the captured images and has a true resolution of about 1440 pixels.


The Panasonic HD cameras developed for 720p production are using 1280x720 CCDs; again, if I have read the specs correctly. Panasonic cameras for 1080i production are also limited by 1440 pixel CCDs.


For readers who aren't up on compression, the Sony HDCam system compresses about 11:1 and D5 compresses about 5:1. As it's pointed out, compression is not a bad thing and in fact makes it more practical to transport digital files from one point to another.


For display purposes, the only imaging systems capable of resolving the detail in a 1080i signal would be 9" CRT projectors (8" comes close, but not quite) and the new JVC 2048x1536 D-ILA device (QXGA resolution). There are no DMDs yet that have this kind of resolving power, nor any transmissive or other reflective LCDs.


KC

 

[Kelvin Colorspace]

Quote:


"As for 1080P/24 transmission, I don't see that happening anytime soon. There are too many problems with broadcast automation systems and monitorong system for a typical station or network to have a 24P plant. It is feasible to pull the 3/2 out in the MPEG encoder and let the STB put it back. I'm not sure if current models can do this.

The NDS unit we have does not."


Not to mention the inherent flicker with running a CRT raster display at 24 frames per second. The refresh rate woudl have to be doubled (48 Hz) or tripled (72 Hz) to eliminate this problem. The only imaging technology I have seen so far that can do 24 fps with no flicker (not noticeable) is DLP.


KC

 

[BarryO]

John,


The ATSC 1080-line formats are 60i, 24p and 30p. Remember that, for film-based material, which represents most of the CBS line-up, there is virtually no difference in the information content of the MPEG2 data stream between 1080/60i and 1080/24p.


1080i at 60 fields (30 frames) per second is generated from the 24fps film via 3:2 pulldown. Assuming the encoder recognizes "film mode", the MPEG2 stream actually consists of 48 fields per second of data, with the appropriate repeat flags so that some fields are duplicated by the decoder in order to generate a 60 field per second output.


If you had the right decoder, you could configure it to output a 1080/24p signal instead. The problem would then be what to display it on. For any type of display technology that uses scanning or other mechanisms where the screen is only momentarily illuminated, the flicker at 24fps would be intolerable. Unfortunately this is the case for also all display technologies currently in common use. So you'd really need to frame-double or -triple at get the frame rate up to 48 or even 72 fps. At this point, we're talking about some fairly expensive iron. But do-able once prices of consumer equipment come down.


IMHO that's why 1080i is the right choice for broadcasting fim-based material. Since the orginal source was captured at 24fps, there's no information content in it that requires the temporal resolution offered by the 60P format. So you might as well use the bits to increase spacial resolution as much as possible. 1080i accommodates today's consumer equipment and also future equipment to present a progressive image with the same temporal resolution as the orignal film, but without pulldown artifacts, at a high spacial resolution.


------------------

You have a right to install OTA and dish antennas on property under your control.


See http://www.fcc.gov/csb/facts/otard.html

 

[Glimmie]

Quote:

Originally posted by Kelvin Colorspace: Quote: "As for 1080P/24 transmission, I don't see that happening anytime soon. There are too many problems with broadcast automation systems and monitorong system for a typical station or network to have a 24P plant. It is feasible to pull the 3/2 out in the MPEG encoder and let the STB put it back. I'm not sure if current models can do this. The NDS unit we have does not." Not to mention the inherent flicker with running a CRT raster display at 24 frames per second. The refresh rate woudl have to be doubled (48 Hz) or tripled (72 Hz) to eliminate this problem. The only imaging technology I have seen so far that can do 24 fps with no flicker (not noticeable) is DLP. KC

Actually the popular 1080/24P isn't really 24 frames per second. The standard in use today is 48sF. SF means segmented frame. The image is scanned progressivily but the lines are split across the two fields. This is similar to striping data across two or more hard disks to gain speed. It is important to understand that is NOT interlace. The damage from interlace is done when the image is captured.


The primary reason this was done is to maintain compatability with 1080i equipment. Most currret design HDTV equipment can do 1080i or 1080/24sf with a flip of a switch so to speak. You can monitor 48fs but it flickers badly. A bit worse than PAL. Therefore we monitor everything with 3/2 added only to look at 48sf for engineering evaluation.


There is in fact a standard on the A53 tables for pure 1080/24P. Panasonic was pushing this against the Sony supported 48sF. It has not taken off and every indication is that 48sF will be the standard used.


One thing you can be sure of, as long as NTSC is still around, there will not be 24P broadcasts. It's just too many problems for the stations and networks. Hopefully when NTSC dies we can get rid of the 59.94 vertical rate and do true 60 or 30 frames. Because of NTSC compatability, 24 frames is really 23.97 and 30 is 29.97. This causes many headaches in the post production process.

 

[PVR]

Just as a datapoint - when I looked at various

CBS shows I came to the conclusion that the intro

to "Diagnosis Murder" is one of the more detailed,

sharpest pieces of 1080i footage coming from CBS, and

much of the material on the "Bette" show looked worse

than 720p even though it was being broadcast in 1080i.


I don't know what "process" either of those items

went through but whatever they were it is a big difference

between the two.


The regions of white background in the Diagnosis Murder intro probably help the MPEG2 encoder focus on the details, but I still think it was "sourced well" to look that good.


Also between the shows there is a wide range of "film grain"

showing. I guess the different shows may be shot with

different cameras and film under different conditions

so it can really vary.

 

[John Mason]

FBT,

Welcome to the forums. Sorry none of the pros familar with this stuff caught your query. I'll take a stab at it based on what I've seen on the 'net; no doubt I'll be corrected if I'm wrong. My understanding was that Sony's HDCAM indeed has 1920 pixel capability with its camera, but that recording was limited to

 

[mmost]

Quote:

Originally posted by Kelvin Colorspace: Unless I am mistaken, there are no HD cameras that currently employ a CCD with true 1920x1080 resolution. The Sony HDCam system sub-samples the captured images and has a true resolution of about 1440 pixels.

The CCD is a true, 2.2 megapixel, 1920x1080 device. The subsampling is done for recording, and is part of the HDCam compression scheme. It is possible to take the 1920x1080 full bandwidth HD information directly out of the camera, either in analog or digital, and record directly to an uncompressed recording device, such as an HD DDR. This is being done by ILM for some miniature and 2nd unit photography on Star Wars Ep. 2. There are various cameras that have true HD CCD's, including the Sony, Philips, and some Panasonic models. The pickup device itself is not the limiting factor, the processing and compression is.

 

[mmost]

Quote:

Originally posted by John Mason: Surely Panasonic has similar models since they market D5-format gear?

Panasonic does not make a D5 camcorder. The D5 format was designed for studio use, not miniaturization and portability, as is partly the case with HDCam. Panasonic's HD camcorders record in the DVCPro-HD format, which uses a variant of the 1/4 inch or so tape used in the DV format and is thus much smaller and more portable.

 

[John Mason]

Quote:

Originally posted by mmost: Panasonic does not make a D5 camcorder.

Thanks. Actually I didn't say they did, and probably should have been more specific. The Sony camera I saw detailed at the pro-gear web site is a large tripod-mounted studio-type model. Thought Panasonic might have something similar -- John