Glossary
The aspect ratio of a widescreen TV screen (also expressed as 1.78:1 or 1.78).
The aspect ratio of a standard TV screen (also expressed as 1.33:1 or 1.33).
Another name for Dolby Digital.
Audio interchange file format. An uncompressed or compressed digital audio file format developed by Apple Computer, Inc. Files have the extension .aif or .aiff.
A representation of an object that resembles the original. Film, VHS videotape, and LP records are examples of analog storage media. The term exists only in contrast to digital.
A widescreen (16:9 aspect ratio) image that has been squeezed horizontally to fit into a 4:3 frame. When played back on a widescreen TV or on a PC, the image is stretched to the correct proportions. On a standard TV, the image may be displayed in its squashed form, letterboxed, or using pan and scan, depending on how the viewer has set up the DVD player.
The shape of an image, described as the ratio of the width to the height. For example, a 4:3 image is one-third wider than it is tall. This ratio is usually expressed in whole numbers (for example, 16:9 or 4:3). Compare with pixel aspect ratio.
Generic term for media file.
The process of collecting and linking individual media elements (video, audio, graphics, and text) to create a DVD.
A recordable DVD disc that is designed for use in professional DVD recorders. Authoring discs let the DVD author write encrypted DVD files to the disc. Compare with General media.
Audio video interleave. A file format for digital video and audio data that is defined by Microsoft Corporation. Files have the extension .avi. AVI files can contain video and audio that are compressed with a wide variety of codecs.
There are two AVI formats: Type 1 and Type 2. Type 1 files contain a single stream of interleaved video and audio. whereas Type 2 files contain separate video and audio streams. DVDit Pro supports both formats.
Bi-directionally predictively coded picture. An MPEG video picture that contains only the information that is different from previous and subsequent frames or fields. See also GOP, I-picture, P-picture.
Binary digit. The smallest unit of digital information. Eight bits make one byte.
The number of bits used to represent the color and brightness of each pixel in a bitmap image, expressed in bits per pixel. A 1-bit image has two (21) colors (black and white), a 2-bit image has four (22) colors, and so on. Full-color images are 24 or 32 bits per pixel; 24-bit images can contain 16,777,216 (224) colors, whereas 32-bit images can contain 4,294,967,296 (232) colors. Also known as color depth.
Volume of data transmitted or retrieved. Measured in bits per second.
A digital image that is represented by a two-dimensional grid of pixels. There are many bitmap file formats, including Windows bitmap, JPEG, and TIFF.
Bits per second. A unit of measurement for data rates.
A backup copy of the IFO file on a DVD-Video disc.
A graphic object on a DVD menu that links to a movie or another menu. When a viewer selects and activates the button, the DVD player displays the linked material. Each button can have a subpicture that changes color and/or opacity when the button is selected and activated.
A unit of data containing eight bits. Digital data storage is usually measured in bytes, whereas digital data rates are usually measured in bits (per second).
Constant bit-rate encoding. A method of encoding MPEG video streams by allocating the same number of bits to every second of video, regardless of its complexity. Redundant data is added to the stream when there is little action, and greater compression is applied (resulting in lower quality) as the video complexity increases. Compare with VBR encoding.
Part of an audio track containing information that is heard through a particular loudspeaker — for example, the left or right channel in a stereo soundtrack.
A marker in the video stream. Chapter points let viewers navigate to specific locations or scenes in the video. The DVD format allows up to 99 chapter points in a movie.
A DVD menu containing buttons that link to chapter points in a title. Also known as a scene selection menu.
A file containing a video and/or audio stream.
A group of pictures whose B- and P-pictures can reference other pictures only within the same GOP. MPEG streams with closed GOPs can be edited, whereas streams with open GOPs cannot.
Coder/decoder or compressor/decompressor. Software that is used to compress video, audio, and graphics files to save space, and to decompress the files for playback.
See bit depth.
A method for making data files smaller. There are two forms of compression: lossless and lossy. Lossless compression, such as that used in PNG image files, does not change the data; it only removes redundancies. Lossy compression involves removing some of the data, based on knowledge of how humans perceive images and sound. Examples of lossy compression include MPEG video, JPEG images, and MP3 audio.
Uncompressed component digital videotape format used for professional-quality video.
See bit-rate.
To process digital data to reconstruct the original (analog) source.
Represented by discrete numbers (digits). In general, digital is synonymous with binary because computers store and process information encoded as combinations of binary digits (bits). Compare with analog.
A software standard developed by Microsoft Corporation for playing digital video and audio on Windows-based PCs.
When spelled with a “c,” it refers to an optical disc such as a CD or DVD. When spelled with a “k,” it refers to a computer disk drive or removable disk. (Computer disks were developed in America and optical discs were developed in Europe and Japan, which is why the spelling is different.)
A codec for creating extremely compressed video files.
A high-quality compressed audio format developed by Dolby Laboratories, Inc. Dolby compression can deliver up to six channels of surround sound.
NTSC-format video contains either drop-frame or non-drop-frame timecode.
The NTSC frame rate is 29.97 fps. Timecode counters cannot count anything less than a whole frame, so NTSC timecode counters increment the second count after every 30 frames. This means that each second on the timecode counter is slightly longer than a real second (0.03 frames, or about one-thousandth of a second longer). This does not sound like much, but over time, the timecode counter will gradually become more inaccurate — after 100 minutes, the timecode will be off by six seconds. This is the effect of non-drop-frame timecode.
Drop-frame timecode keeps the timecode count accurate. In drop-frame video, frames 0 and 1 are omitted (dropped) from the timecode count at the start of every minute except 0, 10, 20, 30, 40, and 50 minutes, so that for example, the timecode count jumps from 00:00:59:29 to 00:01:00:02 instead of to 00:01:00:00. (The actual frames are not dropped, just the numbers.)
Since the PAL frame rate is a whole number of frames (25 fps), PAL timecode counters are always accurate.
Digital Video (note the capitalization). A high-quality compressed component digital videotape format developed by a consortium of companies.
Professional devices that use the DV format for encoding video signals.
DVD stands for Digital Video Disc, or Digital Versatile Disc, or nothing, depending on who you ask. An optical disc storage technology developed by a consortium of companies called the DVD Forum, the DVD format includes standards for storing video, audio, and general data.
A disk or folder containing all the data that should go on a DVD disc. The DVD volume contains a VIDEO_TS folder, as well as other data files and folders that will go on the disc. The DVD volume can be tested by playing it with a software DVD player before it is burned onto a disc.
DVD-Video “plus” Recordable. A DVD disc that can be recorded once.
DVD-Video “plus” Rewritable. A DVD disc that can be recorded and erased about 1,000 times. DVD+RW discs let users overwrite parts of the existing data without making the remaining data unusable, similar to the way that videotape works.
DVD+RW Real Time Recording Format. A video recording format intended for set-top DVD recorders using DVD+RW or DVD+R media. Discs are compatible with most set-top DVD players.
DVD-Recordable. A DVD disc that can be recorded once.
DVD-random access memory. A DVD disc that can be recorded and erased about 100,000 times. DVD-RAM is designed for faster access to random areas of the disc.
DVD-read-only memory. The basic format of DVD, from which all other formats are derived. DVD-ROM discs can contain any form of digital data.
DVD-Rewritable. A DVD disc that can be recorded and erased about 1,000 times.
A standard for storing and playing high-quality video with audio. DVD-Video discs can be played either on set-top players or in computers that have a DVD drive and player software. A DVD-Video disc can contain up to 99 titles.
A proprietary file format used for recording video in Windows Media Center.
A single digital stream of either video or audio. Compare with program stream.
To transform an analog signal into digital data. This often involves some form of compression. See also decode, transcode.
A version of the File Allocation Table file system developed for Windows 98 and later. FAT32 allows files up to 4 GB in size.
A set of TV scan lines. Two fields make a complete frame. One field contains the odd-numbered lines (top field); the other field contains the even-numbered lines (bottom field). The fields can be displayed using interlaced scanning on a standard TV or using progressive scanning on a computer monitor or high-definition TV.
The order in which the fields in a video stream should be displayed. This is either top field first, or bottom field first (DV video is bottom field first). If video is encoded using the wrong field order, it will display correctly on a PC, but will appear jittery when viewed on a TV. Also known as field order.
The logical structure that an operating system like Windows uses to keep track of files on a disk. The most commonly used file systems under Windows are FAT32 and NTFS.
An instruction on a DVD that tells the DVD player which menu or title to display when the disc is inserted into the player.
Frames per second. The measurement of the rate at which video or film images are displayed to produce the illusion of movement.
A single complete image in video or film.
The rate at which video or film images are displayed, measured in frames per second (fps). Film has a frame rate of 24 fps, the NTSC video frame rate is 29.97 fps, and the PAL video frame rate is 25 fps.
The size of the video frame, measured in pixels. Also known as resolution.
Standard abbreviation for giga (billion). When used in units of measurement such as bits or Hertz, it means one (American) billion (1,000,000,000 or 109). When used for measuring bytes of computer data, it means 1,073,741,824 or 230.
Gigabyte. In a computer, this is 230 (1,073,741,824) bytes. In a DVD disc, this is 109 (1,000,000,000) bytes.
A recordable DVD that is designed for use in consumer DVD recorders. You cannot record DVD data that has been encrypted with the Content Scrambling System (CSS) onto General discs (almost all Hollywood DVDs are CSS-encrypted). Compare with Authoring media.
Gigahertz. 1,000,000,000 cycles per second. A unit of measurement for frequencies.
Graphics interchange format. A lossless compressed bitmap graphics file format popular for Web images. GIF images can contain up to 256 colors, support transparency, and can be animated. However, DVDit Pro does not support GIF animations. Files have the extension .gif.
Group of Pictures. A unit of MPEG video, the GOP is a block of video frames of different types. Every GOP begins with an I-picture, followed by a repeating pattern of P-pictures and B-pictures.
For example:
In MPEG-2 video, the I-, B-, and P-pictures can contain either frames or fields. In MPEG-1 video, they contain only frames.
The I-picture contains all the image information for a single frame or field, and is thus only moderately compressed. B-pictures and P-pictures contain only information that is different from the previous or next frame/field, and reference the nearest I-picture for the remaining information. This means they are much more highly compressed than I-pictures.
The number of frames or fields in a group of pictures (GOP
).
For example, a GOP size of 10 looks like this if the I-, B-, and P-pictures contain whole frames:
and like this if the I-, B-, and P-pictures contain fields:
The number of B-pictures before each P-picture in a group of pictures. Typical GOP structures are I B P (one B-picture) and I B B P (two B-pictures).
Hertz. Cycles per second. A unit of measurement for frequencies.
One of the files on a DVD-Video disc. The IFO file contains instructions that tell the DVD player how to play the VOB files on the disc. Because the disc could become unplayable if the IFO file is damaged, a backup copy with the extension .BUP is always included in a separate location on the disc.
A method for displaying an analog video signal on a TV screen. This method was developed because video images flicker when displayed on TVs at 25 or 29.97 frames per second — each frame fades away before the next one appears.
To prevent flickering, each video frame is divided into two fields. One field contains all the odd-numbered scan lines in the frame (the “top” field); the other contains all the even-numbered scan lines (the “bottom” field). The TV displays one field (one set of lines), followed by the next, at 59.94 fields per second for NTSC or 50 fields per second for PAL. At these frequencies, human persistence of vision causes the fields to be perceived as a single image.
Compare with progressive scanning.
Intra-picture. An MPEG video picture that contains all the information necessary to create a single frame or field. Every GOP in an MPEG video stream starts with an I-picture, which provides a reference point for the B-pictures and P-pictures in the GOP.
A picture that shows the disc’s first play menu/title. The jacket picture is displayed onscreen when the disc is stopped in a player that supports the jacket picture format.
A lossy compressed bitmap graphics format developed by the Joint Photographic Experts Group. Files have the extension .jpg or .jpeg.
Standard abbreviation for kilo (thousand). Used as a prefix in units of measurement such as kbps (kilobits per second) and kHz (kilohertz).
Standard abbreviation for 1,024 (210). Used as a prefix in measurements of computer bytes.
Kilobyte. 1,024 (210) bytes.
Kilobits (1,000 bits) per second. A unit of measurement for bit-rates.
Kilohertz. 1,000 cycles per second. A unit of measurement for frequencies.
A method for displaying widescreen (16:9) material on a standard (4:3) TV screen. The entire image is displayed in its proper aspect ratio across the center of the screen. Horizontal black bars (mattes) are added to the top and bottom of the image to fill the gaps between the image and the top and bottom edges of the screen. Compare with pan and scan.
Refers to compression methods that do not throw away any data.
Refers to compression methods that involve throwing away some data to achieve very high compression levels.
Standard abbreviation for mega (million). When used in units of measurement such as bits or Hertz, it means one million (1,000,000 or 106). When used for measuring bytes of computer data, it means 1,048,576 or 220.
Megabyte. 1,048,576 (220) bytes. A unit of measurement for computer data.
Megabits (1,000,000 bits) per second. A unit of measurement for bit-rates.
A screen containing buttons that link to specific locations in a DVD-Video presentation. The viewer activates buttons to display the linked material.
Megahertz. 1,000,000 cycles per second. A unit of measurement for frequencies.
A DVD menu that has a video background and/or animated button images.
A title containing a single video clip. It may also have audio and subtitle tracks. A movie can contain up to 99 chapter points.
A set of standards for compressing video and audio, developed by the Moving Pictures Expert Group. The DVD-Video standard is based on MPEG-2 video compression; the standard also permits the use of MPEG-1 video.
Other MPEG formats include MPEG-1 Layer 3 (MP3) audio and MPEG-4 video. These are not part of the DVD standards.
To combine separate video and audio streams together into a single data stream. Often abbreviated to “mux.”
New Technology File System. A file system developed for Windows NT, 2000, and XP. Its main advantage for video editors is that there is no limit on file sizes.
National Television Systems Committee. The TV broadcast standard used in the United States, Canada, Japan, and a few other countries. NTSC TV uses 525 scan lines (480 lines contain picture information) displayed at 29.97 frames (59.94 fields) per second. Compare with PAL.
A group of pictures whose B- and P-pictures can reference pictures from another GOP. MPEG streams with open GOPs cannot be edited. Compare with closed GOP.
A standard developed by Sonic for creating DVD-Video discs that can be edited by OpenDVD-compliant applications or devices.
See first play.
Predictively coded picture. An MPEG video picture that contains only the information that is different from previous frames or fields. Each P-picture provides a reference point for B-pictures and subsequent P-pictures in a GOP. See also I-picture.
Phase Alternate Line. The TV broadcast standard used in most of Europe and the rest of the world. PAL TV uses 625 scan lines (576 lines contain picture information) displayed at 25 frames (50 fields) per second. Compare with NTSC.
A method for displaying widescreen (16:9) video on a standard (4:3) TV screen. The widescreen image is cropped to fit the 4:3 aspect ratio. Compare with letterbox.
Pulse code modulation. An uncompressed digital audio format. The quality of PCM audio depends both on the sample rate and on the sample size.
Graphics file format developed by Apple Computer, Inc.
One of the dots that makes up a digital image. The size of an image is measured in pixels (width x height).
The ratio between a single pixel’s width and its height. This is usually expressed as a decimal number.
Pixels on a computer monitor are square and have a pixel aspect ratio of 1. Pixels on a TV screen are rectangular: on a standard NTSC TV, each pixel is slightly taller than it is wide, with a pixel aspect ratio of 0.9; on a standard PAL TV, each pixel is slightly wider than it is tall, with a pixel aspect ratio of 1.0666. This is why standard NTSC and PAL TVs have the same 4:3 aspect ratio even though they use a different number of scan lines.
For widescreen (16:9) TVs, the pixel aspect ratios are 1.2 for NTSC and 1.4222 for PAL.
In DVDit Pro, a sequence of titles that play in succession. On a DVD+VR disc, an edited selection of sections from one or more titles.
Portable network graphic. A versatile lossless compressed bitmap graphics format that supports transparency. Files have the extension .png.
A stream containing multiplexed video and audio. Compare with elementary stream.
A method for displaying a video signal on a computer monitor (and on high-definition TV). In a progressive scanning system, the scan lines are all displayed at the same time. To prevent flicker, the scanning frequency must be twice that of a standard TV, but this produces a higher quality picture. Compare with interlaced scanning.
The file that tells DVDit Pro where all the video, audio, and graphics in a DVD project are located, and how to assemble and process them to create a disc. This file has the extension .dvd-dvi.
A software standard for creating, organizing, and playing video and audio developed by Apple Computer, Inc.
Hollywood movie studios release movies at different times in different regions of the world. To prevent the DVD version of a movie from becoming available before it appears in theaters in a particular region, the DVDs have one or more embedded region codes. Every DVD player is supposed to read these codes and only play a disc if one of its codes matches a code embedded in the player.
The process of converting a digital image from one resolution (size) to another.
The size (width x height) of a digital image, measured in pixels.
The red-green-blue color model used in computer monitors. The color of each pixel in an image is made up of a red component, a blue component, and a green component. In a full-color (24 bits per pixel) image, each component can be one of 256 values, from zero (darkest) to 255 (lightest). If all three components have a value of zero, the pixel is perceived as black. If all three components have a value of 255, the pixel is perceived as white. Compare with YUV.
The number of times per second that a digital sample is taken of an analog audio source. Expressed in kHz. Higher sample rates result in a more accurate reproduction of the original sound. The sample rate for audio CD and VCD is 44.1 kHz; for DVD-Video, the sample rate is 48 kHz.
The number of bits allocated to each digital sample of an analog audio source. Larger sample sizes result in greater dynamic range and better reproduction of the original sound. DVD-Video supports sample sizes of 16, 20, or 24 bits.
Secondary audio program. An extra audio track that is broadcast with some TV programs. The SAP track may contain the same program audio in a different language (for example, English-language sports programs in the U.S. sometimes use the SAP track for Spanish commentary), or it can be used for other services such as video descriptions for the visually impaired. Some DVD+VR recorders let you record both the main and SAP audio tracks and switch between them on playback.
One of the horizontal lines on a TV screen. NTSC and PAL TVs have different numbers of scan lines although the screens are the same shape.
Séquentiel couleur avec mémoire (sequential color with memory). A TV transmission standard that is similar to PAL. The DVD-Video format does not support SECAM, so DVD players in SECAM countries play PAL-format discs and transcode the signal to SECAM.
Part of an MPEG video stream. The sequence header contains information about the video stream, such as aspect ratio, bit-rate, picture resolution, and frame rate. The DVD specification requires a sequence header before every GOP.
Data that must be read and processed in a linear sequence, such as digital video and audio. Also known as a track.
Simple 4-bit images that are displayed on top of video. In DVD menus, subpictures are used to create button highlights that ch
ange color and/or opacity when the button is selected and activated.
A bitmap graphics file format developed by Pinnacle Systems, Inc. Files have the extension .tga, .vda, .icb, or .vst.
A small picture that represents the contents of an asset, menu, title, or playlist.
Tagged Information File Format. A versatile bitmap graphics format. Files have the extension .tif or .tiff.
The location of a video frame relative to the start of the video. Timecode values generally use the format hh:mm:ss:ff (hours:seconds:minutes:frames).
Generic term for a movie or slideshow. The DVD-Video format allows up to 99 titles on a disc. Each movie title can contain up to 99 chapter points. Each slideshow title can contain up 999 images.
See stream.
To convert digital video or audio data from one format to another — for example, from AVI to MPEG.
The change from one slideshow picture to another. This can be abrupt — one slide finishes and the next one starts — or can involve digital effects such as fading the end of the first slide into the beginning of the next slide.
Variable bit-rate encoding. A method of encoding MPEG video streams by allocating more bits to complex sections of video and fewer bits to less-complex sections. This results in higher quality video than CBR encoding at the same overall bit-rate, or the same level of quality as CBR encoding at a lower overall bit-rate.
Video buffering verifier. This MPEG video encoding parameter sets the maximum number of bits that can be used to encode a single video frame. If a video file contains a frame that exceeds this figure, DVD players may not be able to decode the frame.
The file directory on a DVD disc (or in a DVD volume folder) where DVD-Video data are stored.
Video object file. The basic media file of the DVD-Video format. VOB files contain multiplexed video and audio.
Uncompressed or compressed digital audio file format developed by Microsoft Corporation. Files have the extension .wav.
Generally used to describe TVs that can display full 16:9 aspect ratio images.
Windows Media Audio and Windows Media Video. Proprietary audio and video file formats developed by Microsoft Corporation and based on MPEG-4 compression standards. WMA and WMV files can be copy-protected, which prevents them from being used on any device that is not licensed to play them. Such copy-protected files cannot be used in DVDit Pro projects.
te speed
The maximum amount of data that a DVD or CD recorder can successfully transfer per second. Usually expressed as a multiplier — 1x, 2x, 4x, 48x, and so on. Generally, a larger number means a faster drive.
CD and DVD discs also have speed ratings. These ratings usually appear as a range of recorder speeds the disc can support. If you put a fast disc in a slow recorder, your recording may fail. To prevent failures, make sure that the disc speed and format are compatible with your recorder.
The color model used in analog or digital video. This model was developed to enable both black-and-white and color TVs to use the same video signal. The video signal is made up of a brightness (Y) component and two color (U and V) components. The Y component is the black-and-white signal. The U component contains the difference between blue and the Y component (blue – Y), whereas the V component contains the difference between red and the Y component (red – Y). This color model is also often abbreviated as YCbCr.