A Primer for Home Theater Newcomers

Vince Maskeeper · 03-10-2002, 09:37 AM

**HTF Ads**

Vince Maskeeper · 03-10-2002, 09:44 AM

DVDs are widescreen (letterboxed), and widescreen is better!

Many first time DVD buyers notice that DVDs are mostly in the "widescreen" or "letterboxed format", which have balck bars at the top and bottom, and they wonder why.

Well, next time you go to your local movie theater, take a close look at the movie screen. You'll find that modern movie theater screens are actually a rectangular shape (they are much wider than they are tall).

[c]

[/c]

Modern movies are shot in such a way that the shape of the picture is a rectangle. While you watch a movie in the theater, take note of how WIDE the movie picture is.

Now, when you get home - take a look at your TV set. Your TV set (if it's a regular TV) is basically square shape. It's not that wide rectangle you saw in the theater, it is closer to a perfect square.

[c]

[/c]

Now- In order to make the rectangle movie picture you saw at the movie theater fit in your square tv, one of these two process is usually used:

1) The studio cuts off the sides of the rectangle picture and make it a square (obviously losing picture area from the original film). This is called PAN & SCAN, and it is probably what you're used to if you watch movies on VHS or on Cable TV. You might have seen the warning "THIS FILM HAS BEEN MODIFIED TO FIT YOUR SCREEN"-- they are letting you know they've cut off big pieces of the rectangle to make it square.

2) The image is zoomed out a little. This allows your set to fit the full width of the rectangle inside the square TV shape, but leaves unused areas at the top and bottom (letterboxing). You see black bars because you are seeing the full width of the rectangle, which leaves no picture for the top and bottom of your square shaped TV.

In order to truly create the THEATER in your home (which is the basic goal of Home Theater)-- it is important to present the film as it was originally intended. The only way to respect the film and present it as the director composed it, is to display it without cutting off parts of the picture. Thus, we have widescreen DVDs.

The proper way to show widscreen films without cutting off the sides of the picture, is letterboxing.

This respect for the original shape of the film is often referred to as OAR, which means presenting a film in its original aspect ratio.

In other words: OAR means presenting the film including the entire picture the director intended you to see. The Home Theater Forum is officially PRO-OAR.

Aspect Ratio is just the term for what shape the movie is in.

You can learn more about widescreen and the importance of letterboxing here (check out the first one for an excellent animated example):

http://www.ryanwright.com/ht/oar.shtml
http://www.hometheaterforum.com/home/wsfaq.html
http://www.widescreenadvocate.org/
http://www.thedigitalbits.com/articl...reenorama.html
http://www.widescreen.org/
http://www.widescreenmuseum.com/

-Vince

Michael Reuben · 03-10-2002, 10:03 AM

What are some common aspect ratios?

Books can be (and have been) written on the history of aspect ratios in motion pictures. But let's keep this basic. In the early days of cinema, movies were roughly the same shape as a standard TV screen, which is about 1.33:1 (which means that the screen is 1.33 times as wide as it is tall). The shape of a standard TV is also sometimes described as "4:3". The terms "4:3" and "1.33:1" are used interchangeably.

Fifty years ago, studios were going broke because theater patrons were staying home to watch TV. So they embarked on a campaign to give theatergoers something they couldn't get at home. That's when movies got wider.

Today, the vast majority of films are framed for one of three common shapes or "aspect ratios":

1.66:1: This is much more common than Europe than in the U.S. When a film is transferred to DVD in this aspect ratio, it will have very small black bars on a standard 1.33:1 TV screen.

1.85:1: Very common in the U.S. Films transferred to DVD in this ratio will have somewhat larger black bars, but still less than a third of the available space on a standard TV screen.

2.35:1: This very wide aspect ratio used to be found primarily in epic adventures, but today it has become common for all sorts of films, even intimate domestic dramas like the 2001 Oscar contender In the Bedroom. Films on DVD in this aspect ratio will have very large black bars, roughly 40% of the available display area.

There's another aspect ratio you may have heard about, 1.78:1. It's not from film. Instead, it's the official aspect ratio for high-definition TV. You may know it by its other designation: 16:9. DVDs have a special connection with the 16:9 format, which is the next subject to address.

What are "anamorphic" DVDs?

Many widescreen DVDs feature what's called "anamorphic" enhancement. You can't always tell by looking at the DVD cover, because the studios don't have a standard format for listing this feature. Often it's referred to as "enhanced for 16:9". Sometimes you'll see "enhanced for widescreen TVs". And often there's no mention of it at all (e.g., most DVDs from Columbia Tristar).

The following explanation of anamorphic DVD is one from the vaults. It was written by former HTF admin Rob Gillespie, and it's the best short explanation of the subject I've ever seen.

Rob's explanation talks about "scan lines". "Scan lines" are what make up the picture on your TV screen. Your TV draws 480 visible scan lines across the screen 30 times every second to "paint" the video picture you see. When films are presented in widescreen, some of those lines have to be used to draw the black bars, which is something of a waste. DVDs offer a way to make better use of those scan lines, and that's what anamorphic enhancement is all about:

Quote:

An anamorphically enhanced DVD spreads the image over more scan lines, increasing the resolution. Where do these extra lines come from? Well, on a normal letterboxed transfer, they are the space used for the black matting bars. If you play such a transfer on a standard 4:3 TV, the image appears tall and thin.

OK so far?

When an anamorphic DVD is played back, obviously the image needs to be restored to it's correct proportions. There are three ways this can be done.

On a standard 4:3 TV, the 'squeeze trick' can be done. This consists of entering the service mode and reducing the vertical size of the viewable picture until the proportions are correct. You're basically doing the same adjustment that's possible on computer monitors. On most European and very few American TVs, there is a proper '16:9' mode which does the squeeze trick at the touch of a button.

On a 4:3 TV without doing the 'squeeze', the DVD player must be set to '4:3' within it's setup menu. This forces the player to 'downconvert' the anamorphic image by removing some of the scan lines. This plays the image back at the correct proportion, but obviously loses some of the original resolution. It can also introduce unwanted artifacts, especially on scrolling credits etc.

On a widescreen TV, if the correct screen mode is used, the anamorphic image is stretched laterally, restoring it to the correct proportions.
Right.

The aspect ratio of the film itself is completely independent to the above. On an anamorphic DVD, the AR can be anything above 1.78:1.

OK?

A normal 'widescreen' DVD presents the film in it's proper aspect ratio (eg. 1.85:1, 2.35:1 etc) but does not include the anamorphic enhancement. This means the image is spread over fewer scan lines, dropping the resolution somewhat. This will play back fine on a normal TV without adjustment, but will obviously have the 'black bars' top and bottom depending on the AR. If played on a widescreen TV, the set must be put into the correct picture mode (on Sony's, it's usually 'Zoom', but varies with other makes).

Phew.

For further information, try here:

http://www.thedigitalbits.com/articl...c/welcome.html

http://www.dvdfile.com/news/special_...anamorphic.htm

M.

Jay Mitchosky · 03-10-2002, 10:52 AM

Home Theater Means Accuracy & Calibration!

Make Video Essentials or Avia and a Radio Shack sound pressure level (SPL) meter a mandatory purchase when you set up a home theater. It's more than just plugging in a bunch of boxes. The goal is to faithfully recreate to the extent possible the theatrical experience. That means setting audio and video levels relative to recognized standards. It only takes a short time to make these basic adjustments but makes all the difference in the world.

For video, colors will be more natural and vivid and the overall image will offer more punch and snap. You will see greater amounts of detail and richer, deeper levels of black. Images will no longer have that blown out, desaturated look like you see on the showroom floor.

For audio you will realize a better balance between each channel. Dialogue won't be obtrusive or lost in the mix. Surround effects will serve to enhance the presentation rather than distract from it. Low frequency effects will not overpower the rest of the soundtrack.

For a fraction of the money you spent on your hardware (and probably software) you can invest in tools that will make movies look and sound closer to the way they were originally intended. And these tools will be appropriate as your home theater evolves.

See also:
A Quick Overview of Home Theater Calibration by Vince Maskeeper

Cees Alons · 03-10-2002, 12:44 PM

All those amplifiers in a HT

Audio signals come from a source (CD player, DVD player, VHS player), then go to a processor to have it divided for multichannel output (Dolby Surround, DTS, Dolby Digital). Then go to pre-amplifier to get some corrections and make it a standard level (also may have treble and bass regulated- as well as overall volume level), then go to (power-) amplifiers who produce power (voltage times current), so it can drive a speaker and make a lot of noise.

If the pre-amplifier and the amplifiers are combined (together with a processor and a radio-tuner as well), it's called a receiver. This is the most common solution in a HT. Therefore, if the power-amplifiers are not all inside a receiver, but apart, that's called separates.

In the old days, when multi-channel audio (except stereo) wasn't common (at least not the "coded" form), there already were integrated amplifiers - of course they still exist, there are many audio freaks around - meaning the pre-amp and the power-amp were together, and generally two of them to form an audio stereo combination.

Cees Alons · 03-10-2002, 01:26 PM

Colour signals

Video signals undergo a terrible form of compression: all those infinite frequencies of the visible color spectrum are represented by only three different colors (frequencies)! The reason they can get away with that, is that it's based on the physiological peculiarities of the human eye. We simply don't see the difference!
The information about the three colors at any moment is called the video signal.

To broadcast the video signal so it could be picked up in our homes, they had to group the colors together and the coding technique was called NTSC. Soon some problems became obvious, especially variable color shifting during transmission through the air. But by then all American TV sets were able to decode NTSC-signals - and nothing else. In Europe they didn't have color broadcasts at the time, so they could come up with a solution: a different way of coding the video signal, which was called PAL. As a result, all TV sets in the US, Canada and Japan can now only decode NTSC signals. All sets in Europe (except in France and Russia) and Australia can decode PAL, and recently most of them NTSC as well.

The digtal nature of the data on DVD made it less desirable to try and code the data as either NTSC or PAL. Instead, they kept the three colors separate, but they used a trick (had been used before): of two colors they record the signal strength and the third value is the total strength of the colors (the brightness). Thus you can easily compute the third color, while in practice a signal is present that can be used in older B/W devices.

To serve older color TV-sets, the DVD-player is able to combine the colors into either NTSC (America, Japan) or PAL (Europe, Australia), and this signal is called the composite color signal. It's less desirable, because immediately after it has just been combined, the TV set will have to split it up again (as it always does) with something called a "comb-filter". The quality of the resulting color image is heavily dependent on the quality (price!) of the comb-filter.

Better use the recorded information, called S-Video (US) or S-VHS (Europe). If your monitor (TV-set or projector) has S-Video input, this is a huge improvement over composite!

Some DVD-players (and all DVD-drives inside PC's) can compute the pure three-color information themselves. This is often called RGB-signal or component signal. In fact the latter term is a bit inaccurate here, because the S-Video is a component signal as well!

You will understand that using the RGB-signal may offer a slight improvement over S-Video (if the decoder is good), but certainly not as much as going from composite to S-Video!

Cees Alons · 03-10-2002, 02:14 PM

Do I really need a Subwoofer?

No, you don't need anything. But then if you don't have anything you won't see or hear much when seated in your HT.

Well, if you're on a budget, or if you need some more time to decide better, you can postpone the subwoofer: that way you can start your HT-experience now, and you will be happily surprised the day you get one!

Why have a sub?
The human ear can hear frequencies starting as low as 20Hz (lower frequencies can hardly be heard - but you can feel them in your chest!). And those terribly low frequencies add tremendously to the drama of the soundstage. No explosion, or earth-quake without them. And they add a foreboding tension to any scene. So they are heavily used in modern films.

On DVD they can be recorded, and the special channel containing them is called the effect-channel, or more accurately: the Low Frequencies Effects (LFE-) channel. It's the "1" in "5.1" (or in "7.1"). Receivers and decoders have an output that is meant to be fed to a special low frequency speaker the (generally having it's own amplifier: active) subwoofer.

Then some guys remembered an older technique. Because you cannot hear where low frequencies exactly come from, you don't have to produce them exactly at the spot of the different audio channels. They used that in older stereo equipment, so they could have less expensive L- and R-speakers, and have all lower frequencies of both channels sent to one subwoofer (located under the couch, or so)!

That's brilliant: now we already have the LFE-sub, we can use it to reproduce the very low frequencies of the other channels as well! No need to buy five extremely expensive speakers (ha, no, not extremely)! All decoders and receivers now have something added called bass-management: you can define any channel you want (often all of them) as small (meaning: no frequencies lower than approx. 80-100Hz), and the decoder (receiver) will send it's bass to the LFE-channel!

So now you know what happens if you add a sub later: you will acquire the possibility to hear the LFE-channel AND you will severely improve your total frequency range. If you were on a budget in the first place, your other channels won't be too good at very low freqs, isn't it? Well, they don't have to be.

Dan Brecher · 03-10-2002, 05:32 PM

As you may already know, the encoded audio information on DVD is digital- meaning the sound has been translated into computer data. When audio is turned into this "digital data", there are several ways it can be written. Much the same way you can express the message "PEACE ON EARTH" in dozens of languages (English, French, Korean, etc)- you can translate audio into DATA using many different systems.

Some computer users might be familiar with formats like MP3 or WAV-- these are simply different ways of expressing audio in the form of computer data. In the wide world of audio, there are literally hundreds of ways audio can be turned into data, or "encoded". Each format has it's own advantages and disavantages.

In the world of DVD, we have essentially 2 major formats for digital audio: one is called Dolby Digital and one is called DTS...

What's to know about DTS?

It is very likely various components within your home theatre (your DVD player for example) sport the DTS logo on the front panel somewhere, but what does this mean? Well, DTS, like Dolby Digital, is another delivery format for digital surround sound (predomenantly 5.1 based) in both movie theatres, and in our homes.

In 1993, Steven Spielberg's Jurassic Park was the first ever movie to carry a DTS (Digital Theatre Systems) soundtrack. A short number of years after it's theatrical launch (which has now seen DTS installed in over 20,000 movie theatres worldwide) the first laserdiscs to carry DTS sound were released to much acclaim, and of recent years much of the home theatre world has been able to embrace a growing amount of DVD releases sporting an optional DTS soundtrack.

As you begin to learn more about the DTS format you're likely to want to ask a number of very common questions, and there are essentially three key questions newcomers are often itching to ask. It is best we tackle each of these one at a time;

1) Why don't all DVDs support DTS soundtracks?

No doubt you have by now noticed, or will come to notice, that not all DVD releases sport the option of a DTS soundtrack. Why is this?

It first needs to be understood that Dolby is the set "standard" for audio on DVD. DTS is an optional format, and frankly, some studios still don't see it as a format that has a wide enough user base to warrant the extra costs of mastering an additional soundtrack for a DVD.

What one must also understand is that the space to encode material on a DVD is far from limitless, and DTS takes up space, more space than Dolby Digital. The additional space DTS requires can often prove problematic when it comes to producing a DVD, and when there is a desire to offer a number of supplements on the disc (not to mention the best video transfer possible) the inclusion of DTS can sometimes be seen as a burden and not a valid enough adition to warrant compromise of a disc's visual presentation. The DVD releases of X-Men and Star Wars The Phantom Menace are among those known not to have included an optional DTS track for this very reason.

2) Ok, so I understand that in some cases the addition of an optional DTS soundtrack is not seen as entirely feasible, even by the studios that support it on DVD, but why don't some studios even support DTS on DVD at all?

Well, again we must return to the fact that some studios just still don't see DTS as a format that has a wide enough user base in the home to warrant the extra costs of mastering an additional soundtrack for a DVD.

Paramount is pretty much the one remaining major studio to have never put out a single DVD that carries an optional DTS track. With them in their lack of DTS support are Warner Brothers, who did in fact issue special editions of Twister, the first three Lethal Weapon movies and Interview with a Vampire with DTS soundtracks on DVD a couple of years ago, though have done no more since. Finally, of the big studios, there is MGM, who have thus far only released one DVD with a DTS track option (Ridley Scott's Hannibal).

The studios that continue to pledge continuing support as and when they see possible? 20th Century Fox, Dreamworks, Universal, New Line Disney. The likes of Anchoy Bay and Criterion continue to show their DTS support on a number of title