Past meetings of the Society
April 1998

Meeting summary by John S. Allen

The April meeting was held at Joel Cohen's place of business, Hi-Rez, in Natick, Massachusetts.

Open Forum

Phyllis Eliasberg asked whether anyone was familiar with a particular Minidisc player; she has had problems with apparent audio compression on one when recording and does not know how to disable it.

David Hadaway: A Chinese movie format called VCD gets a movie on two CDs and is being widely used for bootlegging. Titanic went on sale in China in this format before it opened in theaters here, and the cost was $2.

John Hilliard reported that video rental stores are unhappy with DVDs because they are more easily damaged than tapes [with a tape, you can cause a dropout at one spot by careless handling; a single scratch can completely ruin a DVD, LP or CD -- JSA].

Alvin Foster: Classic Records is selling stereo DVDs -- multichannel ones are due in the fall-and is doing well with them. These are all in 96/24 format. Any DVD player will play them [but not yield full "resolution"-DJW]. Foster now has a computer setup (two satellite speakers and a subwoofers) with virtual Dolby Surround [I have reported on several of these systems, and certain ones even work rather well for groups of several people-DJW.]

Meeting Feature

Joel Cohen took the floor. He described the theme for the transition at this point in the meeting as "from hifi to eye-fi." Hi-Rez and the BAS are lucky that Zenith lent Joel an HDTV projector, which we will be able to view. Cohen introduced Gary Guidi, who remodeled the facility, including building a projector tramway that offers the ability, unique in the USA, to compare five projectors in the same room.

Cohen has a history of turning a pleasant hobby into a business. This was the case with Sound Concepts, and Guidi drew him into this business. Steven Flynn was with Cohen at Sound Concepts as a high-school student. Jim Doolittle, who is independent, does ISF calibration of projectors [and serves as one of Joe Kane's teaching and technical staff during his ISF seminars-DJW].

The store at this location is called Home Theater Systems; believe it or not, the trademark was not taken when they applied for it. Guidi designed the Web site. They sell internationally, and are primarily in the business of rebuilding projectors. Corporations cash-depreciate projectors, and when the book value is down to $1000 but repairs would be $1500, they sell. Hi-Rez buys and rebuilds them.

Only about 5% of the business is in Massachusetts. Two employees do installations as far away as Albany, NY.

The projectors range from a Sony at $1600 to an Electrohome, all used or B-stock. Hi-Rez is just coming on-line with the Zenith. Downstairs there is a room full of projectors that need work. Most of these projectors use cathode-ray tubes. The LCD business is like the computer business: every month, the price goes down and the performance goes up. Hughes-JVC light-valve projectors are beginning to look interesting, and TI Digital Light Processing is getting good too. But Hi-Rez is sticking with CRT technology because it more faithfully reproduces a video signal -- the picture just gets "transported" to the screen "in analog." While a video image is sampled in the vertical dimension by the line structure, it is analog in the horizontal direction, and the conversion to a square-pixel LCD array can result in loss of resolution and in artifacts. Even the TI LCD projector uses a digital presentation with a limited number of brightness levels, and you can see banding. Plasma displays are limited to 640x480 resolution at this time.

The most popular system that Hi-Rez sells today is an 84" or 100" screen with an IEV line doubler and a projector for about $7500. Thanks to Guidi, the place is set up so you can see as many as seven projectors in one visit. Cohen thinks that's bad because customers will want to.

Foster: What are the differences in line doublers? Cohen: a graphics-grade projector can display 1280 x 1024 pixels crisply, and NTSC doesn't even tickle this capability [NTSC is approximately 640 x 480, not taking interlaced scanning into account -- DJW]. There is a lot of difference among line doublers. The most difficult problem in line doubling is interlace. The entire image consists of two fields of alternate lines-1, 3, 5 and so on in the first field, 2, 4, 6 and so on in the second. Since these are at different times as well as locations in the image, the line doubler has to interpolate spatially when the image is moving -- the lines that are not scanned in the current field are blended with the adjacent lines of the current field. The line doubler must interpolate temporally when the image is steady -- using the lines from the previous field. Temporal interpolation requires a lot of fast computer memory, and deciding which type of interpolation to use is not easy [some early line doublers did not do temporal interpolation at all, resulting in a 'blocky' appearance and loss of resolution that was worse than no line doubling at all-JSA]. Line doubling is a very complex task, and the starting price for a box that does it well is about $10,000. Anything that costs less has problems that make the interlace artifacts seem to be less of a problem.

Foster: How about computer systems that include line doublers? A: Cohen doesn't know about Gateway, but Philips looks very good. The Philips DVX-8000 computer system is worth its price as a line doubler. It includes an AV preamp, decent DVD player with a Toshiba drive, and a good line doubler surrounded by a 233MHz Pentium MMX computer. You can play games on it, whatever. It is quite sharp. The Philips has two outputs, for a standard TV display, or to a computer monitor or projector. It has a wireless keyboard and is about standard desktop computer size. For some functions you want the standard remote control, for others the wireless keyboard. You can't get audio for the DVD domain out of the first-generation Philips computer.

Hi-Rez employee Jim Doolittle brought the Philips computer into his theater, so he could connect it to the projection set, instead of bringing the films onto the small computer screen. He runs audio and video through the computer [however, even a good 15" or 17" monitor supports over 1000 lines of resolution and can do justice to DVD material if you don't mind sitting close to the screen-JSA]. The Philips is like getting a good line doubler for the $2000 more this costs than an ordinary computer without these. It also includes a complete audio setup except for the power amplifiers and speakers. It supports resolution up to 800 x 600. You hook up to a data- or graphics-grade projector for its best image.

Foster: Why does Microsoft want a certain scanning system? A: Cohen doesn't know the details. Computer people would like to take over the TV business, putting more progressive scan formats in HDTV. ["progressive" = non-interlaced: better image quality, but like many data formats preferred by Microsoft, requires more bandwidth than the alternative -- JSA] They feel omnipotent. They think they know everything and can continue to grow as they have grown. Microsoft is going in the back door with WebTV and Windows CE, which they have sold to one cable company for the new generation of cable boxes.

There are a lot of problems with HDTV-it is an over-the-air system; Channel Master will rise again. The converter box costs $6000-$7000, and display devices are not capable of everything that HDTV can transmit. It doesn't go over existing cable systems, VHS or laserdisc. It may go over satellite. DTV is trying to do 1920 x 1280 interlaced [as an acceptable compromise even though 1920 x 1280 progressive scan is included in the infamous DTC standard's table 3-DJW]. Bandwidth is a problem.

Backing up to cable, other ways of delivering a competitive signal are possible, and Microsoft is working quietly on that. Frankly, most people are very impressed with a regular NTSC picture blown up to home-theater size, and clean [which few people have seen done properly. Henry Kloss did his best during all his video-projector years, and the technology has gotten a lot better-DJW]. 640 x 480 computer images on a large screen look even better. It seems probable for economic reasons that the highest resolution will not be around except maybe on PBS. ABC is talking about doing 720 lines progressive -- enough detail for rear projectors [for still pictures, 1280I will look better than 720P; for aggressive motion, 720P will look better-DJW]. You can put a couple of channels like that in the 30MHz HDTV bandwidth.

Video guru Joe Kane points out that any given display device can be optimized for only one resolution. Doolittle: The problem is with reliability. Using different scan rates drives the cost right up. If you have 18 different rates, you need 18 different projector setups. He would like to see one scan rate in the projector, and conversion in the box. Several devices are becoming available to scale up from NTSC, but the more complicated issue is to convert from other formats [boxes like the Snell & Wilcox Interpolator do this well-DJW]. All of the display devices capable of HTDV now are multiscan, and that is what is driving the price up. The standards committee says you have to be capable of displaying all of these resolutions without conversion, plus there is the aspect-ratio problem.

The meeting adjourned to the showroom.

We saw a demonstration of an Electrohome projector with Sony tubes. It achieves 130 ANSI lumens, 750 peak (with an LCD projector, on the other hand, ANSI and peak are the same). The projector was scanning at 33.7kHz horizontal, 60Hz vertical-1170 lines, of which 1080 are visible.

A big, unanticipated problem is that the room must be black -- the screen is white, unlike a direct-view screen, and any light in the room washes out the image, so the room must be darkened. A white ceiling reflects light from the image back to the screen and washes the picture out. This lends an advantage to a high-gain screen, with its narrower radiation pattern: the picture looks brighter and ceiling reflections are reduced.

We had a long look at test patterns processed through three line doublers. The IEV looked very clean; the Dwin had serious phase jitter. The QD showed some dot crawl at vertical transitions. To be sure, the test patterns were much more merciless at revealing such flaws than normal program material.

After the presentation was over, meeting attendees were able to view and hear an HDTV sampler program on JVC's WVHS analog HDTC tape. I'm not going to say the HDTV was "just like being there," a common overreaction to a major improvement in technology. Still, the difference between the HDTV and conventional television can be striking. With progressive scanning and 1080 active lines in the image, no scanning lines were visible at normal viewing distance. And the screen was big, about 8' wide in a room less than 20' long. The usual artifacts of VHS tape also were mostly absent; there was no perceptible color noise or image jitter, in particular. There was a slight tearing in areas of the picture with a lot of high-frequency content-for example, the vertical stripes of football referees' shirts when near the limit of resolution. There was also occasionally a little pastel-colored ringing to the right of sharp transitions in color. But there were no dot crawl and no interlace flashing. Though the resolution was not quite as high as with good 35mm projection, the overall image quality was better, in this writer's opinion. Film has artifacts too: grain; the slight weave of the image due to tracking of the film in the projector; and jittery motion with only 24 frames per second. The HDTV image had smooth motion at 60 fields per second and was absolutely steady and free of perceptible noise.

To be sure, this quality reflected top-rate installation and adjustment of the equipment. How many home HDTV setups will maintain this quality is yet to be seen.

In taped coverage of a Duke-UNC football game, close-ups of a pre-game interview revealed how much standard video technique is dictated by the limitations of the medium. The typical staged background and close-in camerawork for a video interview were not necessary with HDTV: the announcer and interviewee were simply standing in the stadium seating, and the landscape behind them was detailed and natural in appearance.

The coverage of the game itself also benefited from the higher resolution and from the wider aspect ratio, though Micha Schattner commented that the camera crew had not mastered the new medium. In standard television coverage of football, he noted, a lot of camera motion is necessary to keep the action in the picture and still show it in enough detail. With HDTV, the camera does not want to be panning as much of the time: you can follow the action across the screen, and the extra camera motion can be annoying.

The piece de resistance of the sampler tape was Ray Charles and his band playing "Georgia on My Mind" at the Montreux Jazz Festival. This was an auditory as well as visual treat. The Hi-Rez viewing room has a fine sound system, with in-wall speakers that did this selection justice. The sharp, steady, artifact-free image put typical music videos to shame.