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Faroudja’s Sawtooth

At NAB’s convention 50 years ago, Ampex introduced the first commercially successful videotape recorder. At SMPTE’s winter television conference 25 years ago, NHK introduced Americans to widescreen HDTV. Is HDTV 25 years old and video recording 50?

Although black-vinyl phonograph records are an artifact of an earlier era, the term “record label” is still sometimes used to refer to those who, like Sony-BMG, distribute recorded music. Once upon a time, there was a Major Radiovision label.

Its disks looked like others of the time and could be bought at a department store. The big difference was that they carried pictures instead of just sounds. The year was 1934.

Videodiscs weren’t the only marvel of pre-1935 television. Videophone calls had already been made, one of them across the Atlantic Ocean. Patrons flocked to see giant-screen theatrical TV. Long before the invention of the image intensifier, there were TV cameras that could see in the dark and peer through fog. There were studio and remote TV broadcasts, of course, as well as network distribution and even some tinkering with color and 3-D TV.

Ampex’s 1956 achievement is rightfully acclaimed because there were no successful video-signal recorders (though pictures could be shot off a screen onto film) from roughly the introduction of the Major Radiovision disks until 1956. HDTV caused the recording drought.

Television before 1936 usually had 30 scanning lines or fewer per frame and just 12.5 frames per second. At those low line and frame rates, a video signal was technically indistinguishable from an audio signal. Recording video on a phonograph disk, therefore, was not much more difficult than recording audio (synchronizing the playback was a little harder).

Sending pictures through a telephone line was little different from sending sound, thus the videophone calls and the network distribution. Theatrical and see-in-the-dark TV had no direct connection to the low line and frame rates, but with television equipment relatively inexpensive and easy to build, experimentation was common.

Then came 1935. The British Parliament had established a television committee to decide the future of the medium. Their report recommended HDTV; it also defined HDTV as no fewer than 240 lines per frame and 25 frames per second.

That’s less than our 525 lines at 30 frames per second, but not as much less as you might expect. The 240 lines were progressively scanned and were all active (picture-carrying). When something close to modern TV was shown at the New York World’s Fair in 1939, it, too, was called HDTV.

The jump from 30 lines to 240 was important. Reviewing the 1934 Major Radiovision text disk fifty years later, Don McLean wrote of one image that it “could be Charlie Chaplin.” But the shift from audio-like video signals to higher bandwidths destroyed much of what had previously been available.

Videophone calls wouldn’t appear again until the 1964 New York World’s Fair, and then only briefly. The first post-1935 home-video recorder was roughly contemporaneous, but it was huge, expensive and difficult to operate.

Video-processing pioneer Yves Faroudja described the history of electronic imaging as an upward trending sawtooth advance. There are incremental improvements (early video went from eight scanning lines at eight frames per second to 30 at 12.5) before a big leap in technology causes a sharp regression of quality or features (in this case, loss of recording and distribution). Then new incremental improvements eventually restore the losses until the next leap in technology.

Black-&-white TV improved until the advent of color, when some say it took a quality hit. Color TV gradually improved, too, moving to chip cameras and cassette recorders at a time when NHK’s version of HDTV required imaging tubes and couldn’t be recorded at all.

Today, HDTV cameras are chip-based, and their signals are easily recorded, but it’s difficult to tell where the sawtooth is heading. On one hand, cameras from ARRI, Dalsa, Olympus and Panavision are moving towards resolutions beyond current HDTV. NHK’s new system has 16 times as many pixels as even 1080p (and, in true Faroudja-sawtooth fashion, sacrifices dynamic range to get that many). On the other hand, video-on-demand is serving tiny mobile-phone screens with pre-1935 resolutions.

At February’s HPA Technology Retreat, Universal’s Jerry Pierce offered a commercial spoof on the giant screens. When the audience finished laughing, he informed them it was 320 x 240.

Content is king.

Mark Schubin is an engineering consultant with a diverse range of clients, from the Metropolitan Opera to Sesame Workshop.