Audio Standards for HDTV Memphis TN

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The ATSC standard includes big improvements in the audio part of television — what you hear as part of any movie, video, or TV show. That’s because ATSC includes Dolby Digital surround-sound capability in the overall standard for digital TV. Dolby Digital (which we discuss in greater detail in Chapter 18) doesn’t always mean surround sound. Some Dolby Digital soundtracks are stereo (two channels) or even mono (one channel). ATSC supports surround sound if a program’s producer and broadcaster want to include it. The NTSC broadcast standard supports only stereo audio (two channels) and not surround sound. Luckily, most DVDs (and some satellite and digital cable TV channels) include Dolby Digital soundtracks that can provide true surround sound. You can also use a home-theater receiver that supports systems like Dolby Pro Logic II (see Chapter 18) to create surround sound from these sources. Dolby Digital and surround sound in general provide an audio soundtrack for TV shows and movies that — wait for it! — surrounds you and provides audio that matches the action on-screen. For example, surround sound might use speakers mounted in the rear of the room to reproduce ambient noises of the setting around the action, or it might give a 3D sense of space to those creepy footfalls of the bad guy sneaking up behind the protagonist. Dolby Digital provides six channels (confusingly called 5.1) of audio. Here’s what they do:

A center channel carries the dialogue being spoken by characters on your HDTV screen.

Two main front channels handle left and right sound cues (and the soundtrack music) in stereo.

Two surround channels (mounted in the rear of the room) provide a sense of 3D space.

A Low-Frequency Effects (LFE) channel conveys deep bass sounds (such as exhausts rumbling and bombs exploding). The LFE channel is the “.1” in the 5.1 naming scheme for Dolby Digital. This channel gets a fraction rather than a whole number because it contains only low-frequency sounds, not sounds for the full range of human hearing. Some new “better than Dolby Digital” standards are being included in Blu-ray or HD DVD disc players. These provide higher-quality audio and more surround channels.

Perplexing Pitfalls
HDTV isn’t the easiest thing in the world to get figured out — we’ve been dealing with it for years and still run into advertising and marketing mumbojumbo that make us say, “Huh?” The whole purpose of this book is to help you wade through the marketing manure and to get you up to speed on HDTV. So without further ado, here’s a list of HDTV danger zones:

Digital confusion: The biggest (and most prevalent) myth we see in the HDTV world is the notion that any kind of digital TV signal (such as digital cable, digital satellite, or DVD) is HDTV. This simply isn’t true. A TV signal must be 720p resolution or higher to be considered high definition. We’ve seen too many people buy an HDTV, hook it up to their existing cable or satellite box, and then wonder why the picture isn’t all that they’d imagined it would be — simply because they’d missed the step of activating an HDTV service to make it all work properly. In Part II, we go into detail about how to get HDTV broadcasts into your HDTV. Sometimes it’s as easy as just changing the channel. Pat doesn’t want to do this, but he’s going to use the example of his dad and brother here. They had set up a new HDTV in Pat’s dad’s home and were watching a football game in what they thought was HDTV — and complaining how awful the picture was. It took about two seconds to change from the standard-definition broadcast on channel 4 to the high-definition one on channel 704. Jaws dropped, and all was well in the HDTV world again.

Input versus display resolutions: When you’re shopping for an HDTV, you can often see marketing and sales literature that includes a huge listing of resolutions that an HDTV can accept. The important thing to remember here is the difference between the resolution of the inputs (the source signals going into the HDTV) and the actual resolution of the picture on the screen. For example, an HDTV might say 480i/480p/720p/1080i on the box but have a display resolution of something like 1,280 x 720. What all these numbers mean is that you can tune into a program at any of these resolutions, and the TV converts the picture to the TV’s display resolution. There’s nothing wrong with this. (It’s the standard behavior of just about every HDTV on the market, including all plasma, LCD, LCoS, and DLP TVs.) However, it leads to confusion when a consumer is buying an HDTV that’s capable of 720p resolution but is convinced that it can display the full resolution of 1080i due to the confusing labeling on the box. One place to pay close attention to this phenomenon is in the case of EDTVs, discussed in the next bullet.

EDTV confusion: EDTVs are TVs (typically 42 inches and under, plasma, flat-panel models) that cost a lot and can display progressive-scan images. However, they don’t meet the minimum requirement of 720p, so they don’t display true HDTV signals. Nothing is wrong with EDTVs; just don’t be fooled into thinking you’re getting an HDTV when you’re not. We see a lot fewer EDTVs on the market today, but do beware: We can’t think of a reason to buy an EDTV when HDTVs cost the same or less in most instances. Although some folks are of the opinion that given a certain viewing distance and screen size you really can’t tell the difference, we’d still rather go with the HDTV variant.

Image scaling: We’re starting to see some new marketing being applied to an old concept — image scalers that can convert video signals from one resolution to another. You most often see image scaling in the case of up-scaling DVD players, which scale a standard 480p DVD image to 720p, 1080i, or even 1080p. This can often generate a better picture on your HDTV’s screen than a plain old DVD player, but it’s not the same as true HDTV (which is now available with Blu-ray and HD DVD discs). Some manufacturers are even marketing these upscaling DVD players as “highdefinition” players, which we find to be almost deceptive advertising.

The DTV tuner: As HDTV (and DTV in general) becomes more prevalent, DTV tuners will become common. These tuners let older TVs “watch” DTV broadcasts. HDTV tuners do not turn older analog TVs into HDTVs. They just convert DTV signals to NTSC for display on an analog TV.

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For Dummies is a registered trademark of Wiley Publishing, Inc. in the United States and other countries. Used here by license.