DVD Glossary -- Image/Video and Audio Terms

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Image/Video:
--4:3 (or 4x3)--
The width-to-height ratio of TV shapes and programs from the 1930s to the early-2000s. Originally, 4:3 was the length-to-height ratio of each frame of film in a reel of film, and 4:3 monitors have the 1.33:1 aspect ratio.

--16:9 (or 16x9)--
The width-to-height ratio of the high-definition TV broadcast standard. This is mandated by law in at least the United States. 16:9 translates roughly to 1.78:1. Numerous DVD producers are changing 1.85:1 movies to 1.78:1 by revealing more of the tops and the bottoms of images or by cropping slightly the left/right sides of images.

--Aspect Ratio--
The width-to-height ratio of an image. Commonly seen aspect ratios include 1.33:1, 1.66:1, 1.78:1, 1.85:1, and 2.35:1.

--Original Aspect Ratio--
Original Aspect Ratio, or OAR, is the image shape that a moviemaker intends for you to see. Typically, a movie or TV show´s OAR is determined at the time of its first exhibition in a theatre or on TV, though sometimes the OAR is changed for artistic reasons.

--Modified Aspect Ratio--
Modified Aspect Ratio, or MAR, is an image shape that was created to fill a TV screen. You may have heard of terms like "full-frame" and "full-screen", but they all mean that a movie or a TV show has been modified from what its makers wanted viewers to see. In the past, most movies with rectangular shapes had their sides chopped off to create a square image, though with the introduction of 16:9 TVs, some square-shaped movies and TV shows are having their tops and bottoms chopped off in order to create rectangular images. (Manga´s "Ninja Scroll: Special Edition" has a version of the movie, which was meant to be shown in 1.33:1, chopped at the top and bottom to "fit" 16:9 TVs as an unfortunate "extra".)

--Interlace scan--
Decoding every other line of a picture from the top to the bottom of a TV and then going top to bottom again for the remaining lines. Denoted with a small "i" (as in "480i" for 480 interlaced horizontal lines).

--Progressive scan--
Decoding the entire image area in one pass. Denoted with a small "p" (as in "720p" for "720" progressive horizontal lines).

--Standard Definition--
480i horizontal lines of resolution. This is what most TVs had up until the late-1990s.

--Enhanced Definition--
480p horizontal lines of resolution. When you see ads for relatively inexpensive LCD and plasma TVs, you´re probably seeing ads for EDTVs that offer better resolution and picture quality than standard-definition TVs but are noticeably inferior to High-Definition TVs.

--High Definition--
Also known as High Def, Hi Def, or HD. This is basically defined as 720p or 1080i horizontal lines of resolution. Some hardware manufacturers are talking about selling DVD players and TVs capable of 1080p, though 1080p exceeds the HD spec. It remains to be seen if 1080p will be incorporated into the HD spec or if it will be considered a part of the next video upgrade.

--Blu-Ray--
An HD technology mostly developed by Sony. Blu-Ray is incompatible with HD-DVD, even though both are blue-laser technologies. Blu-Ray has the support of all the major Hollywood studios except for Universal. However, Blu-Ray machines are hitting the market later than HD-DVD machines, and they are more expensive than HD-DVD machines.

--HD-DVD--
An HD technology mostly developed by Toshiba. HD-DVD is incompatible with Blu-Ray, even though both are blue-laser technologies. HD-DVD does not have the support of the Sony-MGM studios, though it has the backing of major computer software and hardware companies like Microsoft. HD-DVD machines have lower announced prices than Blu-Ray machines and are hitting the market earlier than their Blu-Ray counterparts.

--Super/Ultra Definition--
Right now, there are several terms being used to describe 2K (2000 lines of resolution) and 4K (4000 lines of resolution) technologies. The easiest way to avoid confusion is to use numbers such as 2K and 4K instead of names that have to be defined anyway.

--"Black" or "gray" bars--
Colored bands that sometimes appear above and below or to the left and to the right of an image when watching a video image on TV. The bands help protect the image´s original aspect ratio; therefore, they are NOT preventing you from using all of your TV as they are letting you see the image properly.

--Anamorphic--
In both movie shooting and DVD production, anamorphic processes squeeze images. In movie shooting, lenses squeeze images to fit a squarish (4:3) surface area, either on film negatives or on computer chips. In DVD production, a square image with black bands at the top and bottom of anything wider than 4:3 is still created, so information is squeezed so that a 16:9 TV can display a rectangular image.

--Open matte--
A movie shot in 4:3 but masked at the top and the bottom in theatres with black plates to create a 1.85:1 image. The frame can be "opened up" to reveal the top and the bottom when a movie is transferred to DVD. This explains why some movies have "more" picture in "full-frame" than in widescreen, though this doesn´t meant that you´re supposed to see as much as you do with a "full-frame" transfer. After all, are you supposed to see set lights, microphones recording the actors´ voices, and tape on the floor used to mark the actors´ positions?

--Hard matte--
A movie shot in 4:3 but masked at the top and the bottom in-camera. Therefore, when you look at the film negative or digital video image, you will see black bands at the top and the bottom, period--there is no image to be "regained".

--Super 35--
A shooting process that captures a large image that allows moviemakers to frame movies in various aspect ratios on different parts of the frame. The trade-off of being able to mess with your aspect ratio in post-production is that the Super 35 process typically yields a much grainier image than other shooting processes.

--CRT TV--
Cathode-ray tube TV. Light-bulb-like tubes generate colors that are shown on glass screens. CRTs last for decades, though they are very big and very heavy at larger screen sizes.

--Rear-projection TV--
Color guns shoot varying shades of colors on to the backs of the TV screen, thereby generating images. Similar to how video projectors work (Red, Green, Blue lights shot on to a surface).

--LCD TV--
Liquid crystal display TV. Electricity excites liquids inside of tiny crystals, creating certain colors.

--Plasma TV--
Electricity excites gases inside of tiny gas chambers, creating certain colors. Plasma displays are prone to emitting high-pitch noises that irritate many viewers, and their picture quality diminishes after five years.

Audio:
--Dolby Digital (also known as AC-3 for a short while)--
Audio encoding protocol, deemed the audio standard of future audio broadcast technologies by law in at least the United States, available in the following guises with DVDs:

1.0 (mono; one channel; center speaker only). See Warner and Criterion editions of many movies made prior to 1970.

2.0 mono (two channels; a mono source doubled to the front left and right speakers). This is common with the vast majority of DVDs of movies from before 1970.

2.0 stereo (two channels; discrete information sent to the front left and right speakers only).

2.0 surround (two channels; a fake surround sound mix can be matrixed into the front left and right speakers, thus yielding a passive center speaker and passive rear speakers sharing the same signal; also known as Pro Logic).

3.1 (four channels; active front left, center, and front right speakers plus a subwoofer feed).

4.0 (four channels; active front left, center, and front right plus the rear two channels sharing the same feed).

4.1 (five channels; 4.0 plus an active subwoofer feed). See "Tora! Tora! Tora!".

5.1 (six channels; front left, center, front right, rear left, rear right, plus a subwoofer).

5.1 EX (six channels; 5.1 plus a passive rear center channel matrixed into the surrounds). See "Star Wars I, II, and III".

Pro Logic II (six channels; 5.1 passive signals generated from any source with less than 5.1 discrete feeds).

Pro Logic IIx (eight channels, all active; front left, center, front right, rear left, rear left center, rear right center, rear right, subwoofer).

--DTS--
Audio encoding protocol established as a rival format to Dolby Digital, available in the following guises on DVD:

1.0, 2.0 mono, 2.0 stereo, 2.0 surround, 3.1, 4.0, 4.1, 5.0, 5.1 (same as Dolby Digital configurations).

5.1 ES (same as Dolby Digital 5.1 EX).

6.1 ES (active rear center channel with its own signal feed).

7.1 (same as Dolby Pro Logic IIx).

Note: DTS tracks may sound different from their Dolby Digital counterparts due to a variety reasons, including the use of different audio stems, the use of different audio masters, the use of different engineering practices, etc. For example, some DTS mixes sound "better" or "louder" only because they are encoded at higher decibels than their DD counterparts. If you play those DTS tracks at the same volume as their DD counterparts, then you might get a similar or even an inferior (!) experience with DTS.

--PCM--
Audio encoding protocol that offers "uncompressed" (no audio track is actually ever uncompressed as it is impossible to recreate entirely a real-world audio environment) signals, available in the following guises on DVD:

1.0, 2.0 mono, 2.0 stereo, 2.0 surround (same as Dolby Digital configurations).

--LFE--
Low Frequency Effects (meaning, low sonic frequencies that you "feel" or "sense" more than you "hear").

Note about audio: with most audio receivers, extremely low frequencies are usually routed to the subwoofer anyway, even without an active 0.1 subwoofer signal.

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