NOTE: The "DTV Transition" discussed in this article regards only "over the air" transmissions of analog and digital television signals. While similar technological changes have happened and continue to happen in other transport mediums such as cable and satellite television, these are not changes mandated by the United States government.
WHAT HAPPENED TO FEBRUARY 17, 2009?
After reviewing the state of readiness of consumers and broadcasters across the U.S., Congress approved an extension of the previous deadline to the "new" and "final" deadline of June 12, 2009. Hopefully, this will be the last time I'll have to update this Web page. :-)
OK, so the "TV won't work" tag line of this article is a bit of showmanship - your TV will continue to work after
February 17 June 12, 2009, but will no longer receive transmissions through the air. What follows is attempt to explain just what the DTV Transition means to you, the U.S. television viewer:
*Low Power Television (LPTV) stations, which serve local communities within small geographic areas, will continue to use the NTSC channels indefinitely.
Originally, the FCC set a deadline in 2006 to terminate NTSC transmissions. But because it became apparent that neither politicians, broadcasters, retail manufacturers nor the consumer would be prepared to make the transition, the deadline was moved back to the current and final
February 17 June 12, 2009 date.
A deadline for discontinuing analog television broadcasting is a necessary mechanism to stimulate broadcasters, manufacturers, retailers and consumers to transition to the new standard.
WHY CHANGE AT ALL?
Bandwidth refers to the amount of the finite amount of electromagnetic spectrum available to send signals of any kind through the air in a given location. There is a finite amount of this space because natural laws limit the range of radio frequencies which are possible to transmit and receive. So for any given location, there is a maximum number of video, audio, or other data transmissions which can concurrently be sent and received. The sea change from analog to digital encoding and transport of information has provided, among other benefits, the ability to more efficiently use the available spectrum: i.e., provide many television channels with the bandwidth previously required by one, or provide much higher resolution video in the same bandwidth as analog television. These benefits promise to serve taxpaying citizens with more outlets for a more diverse media landscape.
DTV also incorporates provisions for streaming other data than video or audio over the broadcast transmissions. This might, for instance, periodically deliver news and weather information which is stored locally in your television, to be viewed at the user's leisure. Another application might stream data to a personal computer (although this is a one-way connection, so would not be appropriate for typical ISP services).
SO IS THIS HDTV?
No and yes. The transition all U.S. citizens have been experiencing since 1998 is from analog broadcast television to digital broadcast television, or DTV. After
February 17 June 12, 2009 - with the exception of Low Power Television in a limited number of areas - there will only be DTV transmissions through the air. DTV includes higher resolutions of video, or so-called high definition television, but retains a resolution which is functionally the same as 60 year old NTSC, sometimes called standard-definition. HDTV can look dramatically better than SDTV, but each content provider - be it a carrier such as a broadcast channel or cable channel; a "network" entity, or each television production team can choose to use one of (currently) three resolutions of television (640x480, 1280x720 and 1920x1080 pixels). To realize the benefits of these higher definitions, one must use a display device capable of resolving them, and be suitably close to the display, relative to the display's size (in the extreme, the best HDTV viewed 50 feet away appears to provide little or no improvement over an identically-sized SDTV at the same distance). As this is being written approaching the winter holiday buying season of 2007, HDTVs are reaching all-time low prices while delivering increasing performance-to-cost. Today it is possible to purchase a $2,000 HDTV (the lowest prices for 40" HDTVs are below $600-700) which rivals $40,000 sets of only six years ago. By the 2009 transition, many households will have made the transition not only to DTV, but to HDTV.
WILL OLD TELEVISION SHOWS LOOK BETTER ON AN HDTV?
Not likely. In fact, some HDTVs that look fantastic when viewing HD content do a lousy job of displaying legacy analog TV. That's because in order to display the 640x480 image of the original show on the TV's, say, 1366x768 pixel display, a computer inside the TV has to interpolate which display pixels have to represent the transmitted pixels. In this case, they don't divide mathematically in any convenient way, so some values with represented a single dot are spread across several. Different software "scaling" strategies are employed by different manufacturers on different models, and while some are perfectly viewable, many do a pretty poor job. There is a small enthusiast market for 3rd-party "scalers" - devices specifically designed to "up-res" lower-resolution footage to HDTV while viewing "on the fly." These have typically been prohibitively expensive, costing $1,000 to many thousands of dollars. Some companies have offered lower-priced scalers in the past year or so.
In the not-too-distant future, I expect increasingly economical computing performance will empower every HDTV to provide far superior imagery when viewing legacy footage.
WHY DO SOME HDTV SHOWS LOOK WORSE THAN OTHERS?
Despite the fact that cameras and televisions are considered technically "high definition," there is huge variability between products. This is generally related to cost, so low-budget productions may use low-budget cameras. As a media production professional, I'm particularly sensitive to this, and when watching video-originated shows (all the Discovery HD content, for example), am constantly aware not only of different image quality between shows, but between the good "A" cameras and inexpensive "B" cameras used on the same productions.
A given broadcaster has a fixed allotment of bandwidth, which they can subdivide as they wish. Another attribute of digital media encoding is the choice to "compress" the original content's information to require less bandwidth. While every attempt is made to create computing algorithms to do this with as little loss in fidelity as possible, in practice some loss in image and sound quality over uncompressed signal is typical. How much is up to any party who has the right to manipulate the information: the shooting crew, the editorial staff, the distribution system, the network, the consumer broadcast provider and even the set-top box that finally decodes and records the viewer's programming all have and often take the opportunity to reduce the bandwidth for economic purposes. So a given broadcaster may choose to have one very good-looking HDTV channel, or one somewhat-diminished HD channel and 3 or 4 SD channels, or 8 or 9 low-quality channels. Can a cable channel charge rates for TV commercials 8 or 9 times higher on their high-quality HDTV channel than on one of their many low-quality channels? If the answer is no, the viewers get fuzzier pictures. The digital revolution swings a double-edged sword.
WHY DO HDTVs HAVE A DIFFERENT SCREEN SHAPE?
The relationship of the width of an image to its height is known as aspect ratio. The first television standards adopted the aspect ratio common to most motion picture films of 4:3 (or 1.33:1, although the actual Academy ratio is 1.37:1). As television began to gain popularity in the 1950s, motion picture studios looking for a competitive advantage began exploring technical differences and gimmicks, such as multi-channel sound, 3-D movies and different aspect ratios, which are commonly referred to today as widescreen. These aspect ratios presented the motion pictures in a dramatically different "frame" - much wider than tall. Directors and cinematographers exploited these new formats by shooting broad vistas (appropriate for the Westerns of the time) and by putting actors at the opposite ends of the frame.
Though many proprietary aspect ratios were created and used over the years, only a few remain typical for contemporary motion picture production: 1.85:1, 2.35:1 and 2.40:1.
Historically, when these widescreen productions are broadcast on television, there are two general solutions to compensating for the difference in their aspect ratio and television's, letterboxing and "pan & scan." With letterboxing, the entire image as photographed by the motion picture crew is visible, but black or grey bars appear above and below the movie raster. Pan & scan attempts to fill the television screen by showing only a 4:3 portion of the widescreen image, losing some part of the content on the left and/or right.
Both solutions have their negatives:
There will be a significant period of time of transition during which citizens will continue to use legacy 4:3 televisions - perhaps decades. Likewise, all television productions - particularly those shot on video - will remain forever in their original 4:3 aspect ratio (though some broadcasters mercilessly stretch or zoom these products to avoid or diminish dreaded "bars" on the tops or sides of viewers' TVs). Current standard-def commercial movie DVDs of widescreen movies are recorded anamorphically on the DVD, using every possible pixel represented by the 1:33 standard by first transferring the movie from film to video at 16:9 with some letterboxing. Then the movie is squeezed to fill the 4:3 raster of standard-definition video which DVDs record - this squashed image is an anamorphic image - meaning it is distorted horizontally, which is how some cameras and projectors capture and project 2.40:1 imagery on a 1.37:1 piece of 35mm film. Consumers tell their DVD players whether their televisions are 4:3 or 16:9. When the movie is played back on a 16:9 television, the DVD player knows to send the entire anamorphic image to the television, which is also configured to stretch the image to its original 16:9 shape. If the consumer has a 4:3 TV (here's the trick), the DVD player displays the black top letterbox bar, then simply skips every fourth line of video of the anamorphic image, finally drawing the bottom black bar. The resulting image is de-anamorphicized image. In reality, this image represents a strange kind of distortion, where each 3-line group is actually still anamorphic - distended vertically 25 per cent, but since there are only 360 possible horizontal lines of visual information (as little as 266 lines for a 2.40:1 movie), this is hard to perceive.
DO I NEED TO BUY A NEW TV?
If you are receiving your television programming via cable or satellite provider, you don't need to do anything. Only users of older televisions receiving programming over an antenna must take action.
As mentioned at the beginning of this article, the U.S. Government is prepared to financially assist any household to acquire an ATSC converter box which will allow an analog television to be used to view DTV transmissions. In addition to an ATSC tuner, the user will require a UHF antenna (which can be the same UHF television antenna type which has existed for a half-century).
That said, more programming is being produced in high-definition, and the improvement in image quality can be spectacular. You can only view HDTV on a new DTV, and prices continue to fall. You'll join the HDTV age in time.
WHAT HAPPENS TO THE OLD ANALOG TV FREQUENCIES?
Because the transition couldn't practically be instantaneous, the outgoing analog system and the replacement digital system have had to co-exist for what will be a little more than a decade. This required assignment of some of the precious radio-frequency spectrum (over which anything: cell phones, taxicab dispatchers, air traffic control and military communications must be transmitted) to the new DTV standard.
When our analog television standard was developed, the amount of bandwidth required was based upon pre-WWII concepts and technical practicalities. Television would have to co-exist with broadcast radio and some two-way radio "bands," but little else. In today's information-hungry marketplace and with the efficiencies realized by digital compression and transmission strategies, the old NTSC band will represent a literal gold-mine in radio spectrum. Furthermore, these early television frequencies were deliberately chosen for their propagation characteristics. As relatively low frequencies, they are able to travel great distances and penetrate solid objects such as buildings (compare the very high near-microwave frequencies of some cell phones and WiFi, which can be significantly attenuated by spring foliage on trees). There is absolutely no substitute for this characteristics because of the laws of nature. The FCC will auction off this massive chunk of bandwidth to commercial interests, generating enormous revenue for the Fed. What it becomes has been the subject of great speculation, including fanciful ideas of free nationwide wireless Internet. We shall see...
WANT TO KNOW MORE?
The Federal Communications Commission maintains a website at http://www.dtv.gov/ to explain the DTV transition to U.S. citizens.