Video Tech Glossary, DVD Glossary, VCD Glossary, SVCD Glossary

16:9
Aspect ratio most commonly known as widescreen or letterbox. It is wider than the standard 4:3 aspect ratio. 16:9 supporters state that the wider picture corresponds much better to the human visual field than the almost square 4:3.

2:2 pulldown
The process of transferring 24-frame-per-second film to video by repeating each film frame as two video fields . When 24-fps film is converted via 2:2 pulldown to 25-fps 625/50 PAL video, the film runs 4 percent faster than normal.

2:3 pulldown
The process of converting 24-frame-per-second film to video by repeating one film frame as three fields, then the next film frame as two fields

3:2 pulldown
An uncommon variation of 2-3 pulldown , where the first film frame is repeated for 3 fields instead of two. Most people mean 2:3 pulldown when they say 3:2 pulldown.

3GP
The mpeg4 based video format used in mobile terminals, like cell phones.

3ivX
3ivx is an MPEG-4 toolkit that supports MPEG-4 Video, MPEG-4 Audio and the MP4 File Format.
http://www.3ivx.com/technology/index.html

42
A Mac program that goes directly from DVD to various video formats including VCD , SVCD , and Divx .

4:1:1
4:1:1 Sampling
A ratio used to describe the sampling frequency of a digitized signal. The ratio describes luminance as being sampled 4 times at 3.37 MHz, while color is sampled 1 time at 3.37 MHz in each of it's separate parts. DV, DVCAM and DVCPRO25 use 4:1:1 color sampling. Formulated as: Y (luminance) is sampled at 13.5 MHz (or 3.37 x 4), R-Y (color) is sampled at 3.37 MHz (or 3.37 x 1), B-Y (color) is sampled at 3.37 MHz (or 3.37 x 1) equals 4:1:1.

4:2:2, 4:4:4 and 4:4:4:4
Put simply 4:4:4 and 4:2:2 terms are descriptions of the sample formats used in digital video. In the early 80's tests were done to determine the sample formats and rates for digital video. The eventual sample structure used for SDI video ended up being 4 times the base sample rate chosen.
The first 4 in the 4:2:2 term is for luminance or the black and white information, and this is where most of the picture detail is. Early tests in television human vision discovered a greater sensitivity to black and white information, while the color is filled in with less detailed areas of the human eye. This means you can reduce the color information and your eye cannot really tell. This is what the 2:2 part of 4:2:2 is for. It means the red and blue channels of the video signal are half the bandwidth of the luminance information. Green is not sent, as you can calculate green from red, blue and luminance information.
This color bandwidth reduction has been used for years in broadcast color television, and in fact the color bandwidth of 4:2:2 is much higher than composite video. This all adds up to 4:2:2 being compatible with black and white or composite television, as the color and luminance information is sent separately, while only 2/3 of the data rate is required for about the same visual quality video.
4:4:4 video is similar, but this time all the color information is sent. RGB computer graphics are really 4:4:4. The 4:4:4:4 format adds a key channel.

4:3
Traditional nearly square aspect ratio used for most current analog television screens and IMAX movie theater screens. This aspect ratio will slowly be phased out in favor of the wider, more panoramic and movie-like 16:9 ratio. Video displays using a 4-by-3 ratio display images 4 units wide (horizontal measure) by 3 units tall (vertical measure).

The 4:3 ratio performs fine for television programming, which was designed for it, but it creates problems with movie material originally designed for theater release. The movies are created with a wider, more rectangular aspect ratio (16:9 or wider) in order to create a larger viewing surface and bring the viewer more into the film. On a traditional 4-by-3 aspect ratio display, these movies must be letterboxed or cut down in size ( pan & scan ).

5.1 Audio
In contrast to the Stereo sound system and conventional Surround Systems, this sound system offers five separate full band audio signals: Left, middle, right, rear left, rear right. An additional subwoofer (LFE) channel is also provided.

525/60
The scanning system of 525 lines per frame and 60 interlaced fields (30 frames) per second. Used by the NTSC television standard.

625/50
The scanning system of 625 lines per frame and 50 interlaced fields (25 frames) per second. Used by PAL and SECAM television standards.