Archived Tech-Notes
Published by: Larry Bloomfield & Jim Mendrala The following are our current e-mail addresses:
E-mail = hdtvguy@garlic.com or J.Mendrala@ieee.org
We have copied the original Tech-Notes below as it was sent out. Some of the information may be out of date.
**********************************************DTV Tech Notes - 9
(Formerly North West Tech Notes)
% Larry Bloomfield & Jim Mendrala
521 Forest Grove Dr.
Bend, Oregon 97702
(541) 385-9115
Email = larrybend@aol.com
J_Mendrala@compuserve.com
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October 12, 1997
NWTN - 009
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This has been successful, to date, ONLY with the assistance of those who have helped by contributing information, opinions etc. and have the professional desire to keep on the cutting edge of this technology. Sharing your experiences, knowledge or anything else relating to DTV, HDTV etc. with your fellow engineers is what we are all about. Please keep in mind that this is a work of love and therefore will be published when there is something to share. We've seen the need for our fellow engineers to have a "not so formal" media to express them selves. In this light we're able to keep ourselves and our associates informed. We ask no compensation for our efforts, just the latest information you may have on what's going on. We will not pass on anything that cannot be verified or the source cannot be identified. If we inadvertently pass on erroneous information, we will make every effort to get it corrected as soon as possible. The above disclaimer is for obvious reasons.
Who will we send these issues to? We will make every effort to share this effort with our fellow broadcasters: Anyone interested!. Just e-mail us your request to be added to the mailing list and it's done! Feel free to forward this on to your associates, but let them know that you've done so and it's
not directly from us. If we've sent this to you and you're not interested, just let us know and we will take you off the mailing list.
We publish the addressees e-mail address so that our readers will get a feel for the kind of people who have asked to be subscribers and who reads this thing. We do ask one thing: Out of respect to our readers, PLEASE DO NOT USE OUR MAILING LIST FOR ANY PURPOSE with out our permission.
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With this issue we are changing our name from North West Tech Notes to DTV Tech Notes. The reasoning is that it makes more sense to say in our title what we are about rather than to identify were we originate.
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I hope this the following won't become a regular opening statement, but here goes: "Sorry it has taken over a month to get another one of our Tech Note out to you. As we've said above, this is a labor of love and love sometimes has to come second to other things. We'll try harder this next month.
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From: Jim Mendrala
The SMPTE Hollywood Section meeting could be a possible historic event:
A joint meeting of the Hollywood section of SMPTE with The American Society of Cinematographers (ASC) and the Academy of Television Arts and Sciences (ATAS), Cinematographers Branch.
The event will take place on Tuesday, October 21, 1997, at 8:00 pm, at the Academy of Television Arts and Sciences in Los Angeles, CA
The program is titled "Perfs to Pixels". The pitfalls and joys of attempting to capture the elusive magic of film onto that TV screen.
Speakers: Cinematographers Steve Burum ASC, Robert Primes ASC, Brian Reynolds, Aaron Schneider and Mark Woods wrung out the Kodak Film system by shooting dramatic scenes specifically designed to challenge the system. They will show direct comparisons between 35mm print and telecine transfer.
Paramount's Garrett Smith will compare the relative impact of film clips shown as originally composed and projected on film with scenes both letterboxed onto video and cropped to fill the TV screen.
Artists, engineers, and business people all expect different results from regular television and the new DTV.
Network executives will be invited to debate and discuss the pros and cons of wide screen aspect ratios in a panel discussion with the cinematographers and engineers.
Electronic Cinema (not guaranteed): There might be a prototype of a new technology that could revolutionize the way we see programs in theaters and in the home. More information will be forthcoming if they can pull this off.
There will be a buffet dinner prior to the presentation, at 6:30 pm. Soft drinks, beer and wine will be available.
Everyone is welcome at this free meeting, however there is a charge for the optional dinner and reservations are required. RSVP (for dinner) to Patty Armacost at (213) 969-4333.
The TV Academy is located at 5220 Lankershim Blvd, in North Hollywood, CA
Jim
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From: Jim Mendrala & Larry Bloomfield
There are a number of places on the WWW were you can get information on a regular bases. The following is a list so you can pick and choose at will.
A very interesting web site by Leonardo Chairiglione can be found at: http://drogo.cselt.stet.it/mpeg
Mr. Chairiglione is the person from Italy who is the father of the Moving Pictures Experts Group (MPEG) and the driving force behind its standards for digitized video. There is an interesting article in the September 1997 IEEE magazine "Spectrum" pages 70 thru 78 about Leonardo Chairiglione.
Speaking of MPEG, Audio magazine, September, 1997 issue, also has an article about MPEG in, what can be called, layman's language.
Two addresses regarding DTV and MPEG:
http://www.imedia.com/statmux.html
http://www.c-cube.com/technology/dvx.html
Here are a few more web addresses that you might want to check out.
http://www.sarnoff.com/mpeg/test/bitstreams
http://www.bok.net/-tristan/MPEG/html
http://www.powerweb.de/mpeg/mpegfaq/
http://netvideo.com/technology/technology.html
http://cablelabs.com/R/950372mpeg_ipr.html
If you are interested in film (source of more than 75% of prime time programing) goto:
Jim & Larry
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As has been said: "The road to hell is paved with good intentions." And I guess we had a freeway started. We did have good intentions when we sent out the "Virus Warning.' We got many responses to it. We here at the DTV Tech Notes have learned a lesson. I think one of our readers has said it best:
From: Jim Hancock
"By now you probably have discovered that the Virus Warning you sent out on September 11th was someone's silly idea of a hoax. I did some investigating and discovered that this message has been circulating the Internet for quite sometime and is, in fact, just a hoax. Email is a text message and does NOT carry virus information. It only is able to carry a virus IF it has a FILE attached to it and IF you OPEN the file. The text message, in itself, is perfectly safe. (You might not like what it says but is won't hurt anything inside your computer.)
"For more information about the hoax please see the following WEB site:
http://www.symantec.com/avcenter/hoax.html
"This is the Symantec Antivirus Research Center (Norton Antivirus) and has specific information about real viruses and hoax viruses. For specific information about the viruses in your warning, click on the titles of those listed.
"Don't feel bad. Many people have been caught in this hoax; yours was the second letter I got about the same e-mail viruses. You might want to update those on your e-mail list about this so that the truth can get out to as many as possible. Keep the Symantec web site handy. They are very much up to date on real and hoax viruses."
Jim Hancock
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From: Jim Mendrala
Right now more than 97% of the television broadcasters are in the NTSC mode of transmission. The FCC has passed a new Digital Television Standard for DTV. DTV has built into it the delivery of SDTV images and sound on up through HDTV with its AC-3 stereo surround sound, plus the ability to transmit data on top of all that and still remain within the 6 MHz channel!
A lot of TV station management are concerned about spending lots of money to convert to the newer technology saying that the public will not spend thousands of dollars to get a HDTV set in there home. The price for these new DTV receivers will drop as time goes on. I don't presume to give marketing lessons but hear are some simple principals.
In the first few years there are very few buyers and very little competition or variation of a product type. As time goes by and the market is educated and products sell more units. This amortizes the R&D costs which drops the price. Because the price drops more people are interested. The numbers of DTV receivers sold will increase which makes manufacturing cheaper. (a unit costs less to make when you make 100,000 units at a time than when you make 100).
Some examples of this are:
AVS ADAC Standards convertor (4f/4l) approx cost in 1985 = $100,000 Snell & Wilcox CVR-45 Standards Convertor (4f/4l) approx cost in 1997 = $25,000
286/16MHz PC in 1985 sold with 20Mb HD & 1Mb RAM = $2,000
Pentium Pro/200Mhz w/ 16Mb RAM & 2 Gbyte HD = $1,600
Data Projector (CRT Type) in 1987 = $50,000
Data Projector (CRT Type) in 1997 approx $30,000
LCD Portable Data Projector in 1997 approx $5,000
I could go on.. but the problem is not that DTV costs will come down, the real problem is the content. When all the FCC agreed upon a delivery system & standard, the broadcasting community will have to supply appropriate content to sell it to the real world of viewers. Viewers like you! They are the ultimate customers.
We should be pushing for wider screens and higher resolution so we can get on with what we do.
I will get off my soapbox now. I know there are many others with far more qualifications and more to say on the topic than me. I am also sure they will say it more eloquently.
Jim
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Also from Jim Mendrala: The following is feedback on the above article. I sent a copy of it to Rich Zabel, who is the Eastern Sales Manager for Tekniche, Inc
"Your points are well taken and I agree with them except.......
"One BAD Example, ADAC is still a better converter than the CVR-45. A more direct comparison is with a Tekniche (AVS) CYRUS or a S&W Alchemist which are in the $65,000 Range.
Rich Zabel
Eastern Sales Manager
Tekniche, Inc
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(Ed Note: As of right now there are more than five HDTV telecines in use in the greater Los Angeles area and more are coming. The movie studios are gearing up for the demand for Content. With this in mind, the following is something from Bill Hogan that might be of interest.
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From: Bill Hogan
Subject: DVD-From Where and How
Howie Burch wrote:
" Hi everyone:
"I just viewed a DVD of a film called "Murder at 1600" and am curious as to who did the transfer and on what system. Also what compression system was used.
"If any one has the answers, I'd appreciate it.
"Howie Burch
"Nice Shoes"
The film that you ask about is a Warner Bros. title and with the building of the "on-lot" Video Operations Department most of the new current releases are transferred there. Chris Cookson, Gary Morse, Paul Klamer and Jan Yarbrough and the rest of the crew have developed some unique methods of feature film transfers.
On inquiry this is what was done for this title.
The transfer was done on a Standard URSA Gold with no after market add-ons to the telecine. Keith Shaw was the colorist. Color Correction and Telecine Editing was accomplished with a Pandora/Pogel equipped with DCP that was fed from the 4:4:4 telecine outputs. Secondaries can be tweaked with both Cintel and DCP corrections. This is where all standard methods of operations end.
All telecine transfers are made at 625 lines. The rooms are rarely switched to 525 to make a domestic transfer. In the case of an anamorphic title the transfer is made with all 625 lines scanning the squeezed film image. For purposes of viewing, the monitor is operated in a vertical reduced scan mode for proper aspect ratio viewing. Noise reduction is in the path after correction. This is a Digital Vision DVNR-1000 Box with the V-Zoom option. The V-Zoom processes the vertically stretched image to a standard letterbox picture. This allows the telecine image (all 625 lines) to be used for the letterbox on-screen image. This results in a much-reduced amount of vertical alising. This output is a standard 625-25 frame letterbox tape. This output is recorded to an Ampex DCT VTR, a tape format chosen for its robustness, interchange ability and 525/625 operation. This recording is of course made at the normal 625 digital 4:2:2 standard. (Warner
Bros. Burbank is possibly the world's largest user of Ampex DCT machines and tape.)
These machines have what is now a standard Ampex feature (not an option) that allows the VTR in the 625-25 Frame mode to be switched to playback at 625-24 (Twenty-Four) Frame. This above 625/24 signal is fed to a Digital Vision (AFC) Anamorphic Format Converter unit. This was developed first for Warner Bros. but is now available for anyone to purchase.
This AFC Unit was developed to do several things, depending on which options were purchased. First it can take an Anamorphic Image and center scan it or can pan-scan the image under computer control. It can also pass the image thru as the input, in this case an anamorphic image. Second and most important is its ability to convert the 625 line/24 Frame signal to a 525 line/30 Frame signal. In other words the input signal was 24 Frame Progressive 625 lines and the output signal is 525 line/30 Frame interlace with the 3rd field added just as the digital frame store in the telecine does. The vertical down conversion or vertical filtering completely eliminates any last artifacts of the telecine scanning vertical alising. This has been in operation for over 3 years at WBVO.
This 525 line/30 Frame Interlace tape now goes to the video compression operation for 525 DVD Disks. A Toshiba DVD compression system was used. This is located at CVC (California Video Center-a Warner Bros Division that is also the master control playback operation for the WB-Warner Bros. TV network.) The first operation that the compression system does is discard this 3rd field that was added and convert the signal to a 525 line/24 Frame Progressive video signal for further processing. (Does this sound familiar? -- see above) Of course this signal is virtually free of vertical artifacts and therefore compresses better using less bits for a better DVD image. The DVD Disk is made with all the other audio and other data added. You buy or rent this DVD disk for home use The DVD home unit processes this 525/24 Frame Progressive signal to a 525/30 Frame Interlace signal for your television display.
It adds the 3rd Field for every other film frame.....you have a Digiscan/Telecine Framestore in your DVD player at home for less than $500. Who says that technology is not amazing? DVD players have 4:2:0 Digital Signal processing internally which is up-converted to 4:2:2 to output to composite, component Analog outputs or S-Video (almost as Good) outputs to feed to your home display.
The audio and the timecode considerations are for another time.
I think I got a little off the subject of Howie's question. But recent discussion about HDTV and the viewing public's lack of seeing a decent signal that they might even think is HDTV got me carried away.
Bill Hogan bhogan@sprocketdig.com v.818-566-7700
Sprocket Digital Burbank,CA f.818-566-4477
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HDTV discussion thread is at http://www.alegria.com/telecine/hdtv.txt
(Ed note: Larry Bloomfield's son has works for Sprocket Digital.)
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From: Larry Bloomfield
In our last issue we talked about how HDTV was dealt a setback. Well it looks like the industry "tweeked" congresses nose and the politicians responded. They sure do speak out of both sides of their mouths! In one breath they say: "Let the market place set the standards" and yet in the next, you hear: "do it our way or we'll fix you." Sure sounds like kids scrapping in the back alley. Make no mistake about it. I'm in favor of promoting our ever advancing technology. I do, however try to look at things with a practical eye. If we lived in a "perfect world", HDTV screens, as big as your living room wall, would grace the home of every television viewer from Bangor, Mane to Hilo, Hawaii and from Blane, Washington to Key West, Florida. Every television station in the nation would deliver a progressive scan picture, 1920x1080 pixels at 60 frames per second, which gives us
approximately a 30 degree viewing angle. (Present day NTSC television gives only about 7 degrees or less viewing angel.) This is why you'd want a big screen to view the new HDTV on some as to take advantage of this new and much better picture. HDTV has to be displayed properly or it won't sell. Make no mistake about it, HDTV isn't just wide screen NTSC. DTV isn't HDTV, it's encompasses all existing and future formats. DTV is a methood of delivery, not a format.
In the previous article you've read about how DVD is being done at one of the major studios. It says: "All telecine transfers are made at 625 lines." For the life of me I don't understand why. They're missing the boat. These transfers will not have the quality to be used in HDTV. They, too will have to be retransferred to meet the minimums standards of HDTV or do they plan to bump up this lower quality and pass it off as part of the new technology. I hope not!
We have said in one or more earlier editions of this newsletter that to meet the needs of HDTV, doing this format justice and at the same time being able to accommodate all the lower quality formats (eg: NTSC, DVD, PAL etc.) the telecine equipment must have the highest capture capability possible. We must think in terms of film to data (digital) transfer rather than film to tape. You can always delete bits that you don't need when reassembling the video information in a lesser format, but you can never get quality by bumping it up.
A corporate officer of a major television transmitter manufacturer asked me just this past week where his company could get a device that would convert NTSC to HDTV as an interim measure until programing could be developed in the proper format. I can think of no faster way of making a silk purse look like a sows ear. He is in an envious position compared to the folks who have to make studio equipment. All he has to do is to make a device that will pass the high bit rate required within the prescribed bandwidth. It reminds me of the guy, in the early days of color television, who invited me over to see a black and white show on his new color set and then could understand why it didn't look as good as on my old black and white.
In closing, if you want to make big bucks, in the near future, build a telecine facility to transfer film to data at the greatest rate you can get. The current NTSC film/tape libraries and it sounds like the new DVD libraries will not be of much use to the folks who will want to broadcast in the new DTV/HDTV world of television. As of right now there are more than five HDTV telecines in use in the greater Los Angeles area and more are coming. Are they now and will they in the future be doing things to meet the needs of these new standards. As both Jim Mendrala and I have said in the past, partly in jest, just find us the money and we'll build it for you, lord knows we know how.
These are my opinions, Lets hear yours,
Larry
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The DTV Tech Notes are published for broadcast professionals who are interested in DTV, HDTV etc. by Larry Bloomfield, Chief Engineer, KTVZ, Bend, Oregon and Jim Mendrala, Consulting Engineer, Val Verde, California. We can be reached by either e-mail or land line (541) 385-9115, (805) 294-1049 or fax at (805) 294-0705. News items, comments, opinions etc. are always welcome from our readers; letters may be edited for brevity.
larrybend@aol.com --------- J_Mendrala@compuserve.com
NWTN articles may be reproduced in any form provided they are unaltered and credit is given to the North West Technical Notes and the originating authors, when named.
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