NTSC television uses its own methods to suppress flicker. In the first one-sixtieth of a second, all the odd-numbered lines of the line picture are transmitted. In the second one-sixtieth of a second, all the even lines are transmitted - and the screen glows persistently enough that the odd lines are still illuminated while the even lines are inserted between them.
Why not transmit the whole picture every one-sixtieth of a second, instead of just half of it? Because when the NTSC format was developed in the s, half a picture was the most that could be sent in one-sixtieth of a second within the available bandwidth. Unfortunately, interlacing creates some ugly visual defects. Consider a live transmission of a football zipping across the screen. During the first one-sixtieth of a second, the odd-numbered scan lines show the ball on the left.
By the next one-sixtieth of a second, the ball has moved, and the even-numbered scan lines show it in the middle of the screen. The odd-numbered lines are still visible, so we see the ball in two places at once. This generally means that fast-moving objects seem smeared or fuzzy in an interlaced display. It also means that if you do a freeze-frame, or if you save a video image as a still picture, objects that were in motion will appear extremely blurred. Interlaced video also runs into trouble displaying thin horizontal shapes.
If the shape is so thin that it coincides with only one of the scan lines, it will appear only in alternating frames, causing it to flash visibly 30 times a second. To suppress this effect, TV cameras automatically thicken any horizontal shape so it will cover at least two scan lines.
This of course reduces the amount of detail that the picture can display. New problems occur when an interlaced picture is digitized and compressed. Compression schemes such as MPEG work by sampling a picture and simplifying it - but an interlaced transmission sends only half the picture at a time. If each half is separately compressed, they may not be a perfect match after they are decompressed by the TV receiver at the receiving end. Interlaced displays were abandoned by the computer industry years ago, when users started demanding high-quality graphics featuring fine lines and minimal flicker.
All computer monitors now generate a complete picture every one-sixtieth of a second. In Europe, for historical reasons, the standard is every one-fiftieth of a second. When video is created this way, it's known as noninterlaced or progressive scan , meaning that each whole frame is drawn on the screen progressively from top to bottom without skipping any lines.
During , according to the Consumer Electronics Manufacturers Association, about 9. By comparison, about Noninterlaced monitors still lag television sets in market penetration, but they're clearly gaining ground, and it seems foolish to ignore their importance as a display medium.
Why not get rid of this cheesy cost-cutting practice once and for all, in the interests of true compatibility? The Grand Alliance violently disagreed with such arguments. Some of its members claimed that consumers would never watch TV on computer monitors, simply because the screens are too small. Well, certainly the computer industry had its own interests in mind. It believed that people would want to watch TV on computer monitors, and it hoped to benefit. It also liked the idea of transmitting computer graphics via TV.
This simple desire to meet consumer demand surely seemed reasonable, especially compared with broadcasters' yearning to exploit their free spectrum with "other services. A progressively scanned picture will always contain twice as much data as the same picture transmitted in interlaced mode. Therefore, it will always require twice as much bandwidth. This is true even if both pictures are compressed.
Clearly, if a TV station owner wants to free up as much "spare" bandwidth as possible, he won't transmit a high-quality, high-capacity progressive scan. He'll stick with the low-quality interlaced mode while claiming that no one can tell the difference. Therefore, the coalition was in no mood to compromise.
The old aspect ratio would be eliminated, and the previously proposed ratio would be expanded to to make it suitable for CinemaScope movies. Images would be encoded using a system similar to Kodak photo-CDs.
A low-resolution "base layer" image of 1,by pixels would be broadcast for cheap, low-quality receivers along with extra information to tell higher-quality TVs how to enhance the "base layer" to create a superhigh-res 2,by-1, HDTV picture. This system would enable easy upgrades, because the base layer of data would always stay the same while the fine-detail data could be enhanced to the limits of future technology.
Cheap low-res TVs really could be cheap after all. Broadcasters were appalled. Every other format would be eliminated - including dear old NTSC! There'd be no room at all for "other services. They would have to transmit HDTV. Did the FCC take a side in this final standards battle?
Not at all; the new kids were just as welcome at the birthday party as the kids who had been there originally, and if they wanted to promote their own plans for grabbing more cake, they should go right ahead. Meanwhile, in public statements, he remained noncommittal on the formats issue. Wasn't there something a little odd about this? If the FCC wasn't willing to mediate - if it wouldn't endorse one format over another or do anything to expedite the decision making process - then what was it good for?
Reed Hundt gives wonderful speeches. They're witty and charming, and they send corporations a message that they love to hear: that government shouldn't stand in the way of the free market.
And yet, there are some areas where Hundt appears to assume that regulation is essential. On a talk-radio show, when a listener asked him how she could complain about TV programs that she found offensive, he told her there was going to be a toll-free hotline.
Hundt may not have been totally serious the number has never been implemented , but the FCC has been deeply serious about prohibiting indecent speech on radio and TV. It almost had its license yanked when one of its disc jockeys played some off-color records. Howard Stern is a notorious talk-radio personality. All radio stations are painfully aware that they face severe penalties if they violate FCC guidelines. And the FCC goes even further, "discouraging" material that it happens to disapprove of such as liquor ads on TV even when this content violates no state or federal laws and is protected by the First Amendment.
This heavy-handed behavior may seem to violate the no-hassles relationship between the government, the FCC, and the broadcasting industry, but on closer inspection it poses no problems. Broadcasters, after all, don't have to use four-letter words on the air in order to make money. In fact, since the indecency ban affects them equally, it doesn't diminish anyone's market share. Thus, the FCC can look as if it's doing something useful without hurting broadcasters in the area they care most about: profit.
The FCC is more cautious about telling stations what they must broadcast. Still, it had to placate consumer groups about the loan of new channels, so Reed Hundt suggested, in an apologetic tone, that each broadcaster should have to devote a minimum number of hours a week to educational children's programs, plus free prime time for political candidates during the election season. Where else have we seen this paradoxical mix of conservative free-market rhetoric and social engineering?
The name Bill Clinton may come to mind, and - surprise! Hundt was appointed by Clinton. He attended St. Does Hundt really believe his own speeches, or is he a high-class ventriloquist act, with Clinton doing the talking?
To find out, I visited him at the FCC. He's a handsome, charming man, with a youthful grin and a full head of thick black hair. He gave me a firm handshake and a warm smile as he welcomed me to a huge office where a conference table stands beneath an American flag that covers an entire wall. But as he started talking, I realized that the no-bullshit rhetoric of his speeches is misleading.
I found myself dealing with a seasoned political animal no different from any legislator parrying questions on Meet the Press or Face the Nation. Ultimately, he projected as much sincerity as a photocopy machine salesman. He also minimized my opportunity to ask questions with the time-honored tactic of giving very long answers. I began by asking how much airtime he would demand for public services.
Hundt spent a good five minutes reflecting lyrically on the vital importance of broadcasting as a national resource. Finally, he said, "Broadcasting licenses are granted in return for delivering free TV for the public good. Digital TV licenses should perpetuate that idea; it is a wise idea to guarantee that certain dimensions of the public good be served. Children's programming, and free time for political broadcasting - perhaps 5 percent of airtime - could be devoted to those purposes.
And where did he stand on the interlace question? This provoked an even longer stream of eloquent waffle. The closest I could get to a definitive statement was when he told me that "for broadcasters to take the interlaced idea and add it to high definition is to make a unique product, but maybe in the same way as the pressure cooker - everybody said it was going to sell like hot cakes, but it didn't.
He was reluctant to be more specific. But he seemed enamored of the computer industry, and he referred to Bill Gates as a "genius. Turning to HDTV, would he really not require broadcasters to transmit high-definition pictures? Would he allow them, instead, to transmit the same old NTSC programs in compressed, digitized form, letting them sell "other services" on the side, demanding nothing in return, even though the spectrum could be worth billions of dollars? Hunt responded by asking a question: "How much broadcast TV is enough?
An equal number of channels. Beyond that, let's allow them to use the digital bits for whatever they want, including sending software application packages over the air to PCs with digital antennas, some subscription services so that digital broadcasters can have a revenue stream, and multichannel packages that compete with cable and satellite digital. But wait. If broadcasters are free to cram all these moneymaking schemes into a traditional 6-MHz channel, there will be no room left for an HDTV signal.
Won't this mean the death of HDTV? Hundt shrugged and gave me his synthetically charming smile. Cable doesn't want to deliver to it, satellites don't want to deliver to it.
Why this is a good business plan for broadcasters is a mystery. Well, HDTV isn't a good business plan for broadcasters so long as they retain their government-sponsored monopoly. They'd be crazy to spend money on fantastic display quality when they can simply exploit a captive audience with low-quality video that uses as little bandwidth as possible. I left Hundt's office with the clear impression that he had no interest whatsoever in mandating a better TV picture. Of course, Hundt does not control the FCC; there are four commissioners, each with a vote equal to his, and not all of them share his enthusiasm for procrastination.
Earlier in November, commissioner Susan Ness demanded that broadcasters, manufacturers, and the computer industry reach a final, definitive agreement before the end of the month.
Suddenly it seemed as if a definitive standard might be set after all. But when the result was announced on November 25, it was a bad joke. From the earliest days of radio and television, through the birth of digital broadcasting to the emergence of video over the internet, Arqiva has been at the heart of the industry for nearly years, trusted by broadcast and media brands across the globe.
Digital technology means that we can now get a much better handle on how much gas, electricity and water we all consume. Arqiva works across the utilities sector to make this happen. Through our efforts, energy and water grids and meters are getting smarter, meaning more control, and less wastage. For energy and mobility companies, satellite operators, military organisations and telecoms providers, secure networks are vital when working in locations that are remote or hostile — guaranteeing that communications always get through.
Which is what you get when you use our global satellite, teleport and fibre networks. Westinghouse High Definition Roku TVs offer an unequaled entertainment experience that fits your lifestyle, your way.
Watch exactly what you want, how you want, when you want. Feature-packed with built-in Wi-Fi connectivity, access to your favorite entertainment has never been easier. Read more…. My Life. My Way. My Westinghouse.
Enjoy endless entertainment that fits your lifestyle. I work hard. I game hard. My Westinghouse monitors do too. Feature-packed Smart TV. HD TV. Get your game on with dedicated Gaming Monitors.
0コメント