This article discusses when, why, and where you will see black bars while watching a movie from a DVD-Video disc with Apple DVD Player.

Question Why are there black bars on the top and bottom of the movie I'm watching from a DVD-Video?

Answer
The distributor of the movie wanted you to enjoy the full widescreen version of the movie. Because the movie has a wider aspect ratio than the average computer monitor and television, black bars are placed (or matted ) onto the video.



Question What are "aspect ratios" ?

Answer Movies on DVD-Video discs have many different aspect ratios (the ratio of a movie image's width to its height). These ratios are expressed in units of width to units of height. The most common ratios for movies on DVD-Video discs are 1.33:1, 1.85:1, and 2.35:1. Most televisions and computer monitors have a fixed ratio of four units to three, often expressed as 4:3. Some televisions have a ratio of 16:9, also known as widescreen or letterbox.




Question How does the aspect ratio of the original movie differ from that of the video on the DVD?

Answer The video on the DVD itself is in standard NTSC or PAL format such that the aspect ratio is always 4:3. So, the aspect ratio of the original movie must be adapted to the standard aspect ratio of 4:3. How this is accomplished, combined with the aspect ratio of the screen used to view the DVD, will determine whether black bars appear, where they appear, and how big they are.




Question I see movies on television all the time that have no black bars. Why do I have to see them now?

Answer Movies on television are often cropped so that the movie fits the entire screen. Depending on the original aspect ratio of the movie, up to 40 percent of the picture can be lost. If you prefer movies in this format, look for DVD-Video titles that include a "standard format" version.




Question I get black bars on the sides of the screen. Why is this?

Answer If your display is wider than 4:3 (like the Apple Cinema Display at 8:5 or the PowerBook G4 at 3:2) and the DVD-Video title uses a 4:3 aspect ratio (like a standard format movie or any content that was originally broadcast for television), the picture would have to be stretched horizontally to occupy the full width of the screen. Further, widescreen format DVD titles will have bars on the top, bottom, and sides of the screen if they are not anamorphically encoded and are viewed on a wide-format display.




Question What is anamorphic encoding?

Answer Some movies use anamorphic encoding to minimize the use of the black bars and increase the resolution of the picture. This technique stretches the image vertically before transferring it to the 4:3 format. When the movie is played back, the DVD player detects that it is an anamorphic title and stretches the video horizontally. If your display has a wide format aspect ratio (like the Apple Cinema Display or the PowerBook G4) the movie can span the full width of the display. When anamorphic encoding is used, the resulting video occupies a 16:9 aspect ratio. DVD-Video titles using this encoding will usually state on the back of the box that the movie uses anamorphic encoding, or has been "enhanced for widescreen TVs". However, some titles do not state this feature on the box at all.