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Video and Codecs therms
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A B C D E F
G H I J K L
M N O P Q R
S T U V W X
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3ivX - Video format based on MPEG-4 video standard with certain modifications. 3ivX can be compared pretty easily to DivX ;-) format,
but in this comparision 3ivX unfortunately loses in quality (at least currently, 10/2001). 3ivX is pretty popular format among Apple MacIntosh
users, because of its extensive support for Mac. In other hand, Windows users have stayed away from this format because in its original format,
3ivX had to be stored in QuickTime file structure instead of AVI file structure -- most of the Windows-based video editing tools don't support
QuickTime, but either AVI or ASF instead
3GP - 3GP is the MPEG4 based video format used mostly in mobile terminals, such as mobile phones. This file format is designed for
3rd generation mobile devices. 3GPP is defined by the 3rd Generation Partnership Project and 3GPP is defined by 3rd Generation Partnership
Project 2. They are the worldwide standards for the creation, delivery and playback of multimedia over 3rd generation. These standards
seek to provide uniform delivery of rich multimedia over newly evolved, broadband mobile networks (3rd generation networks) to the latest
multimedia-enabled wireless devices, such as cell phones
4:1:1 - this is a set of sampling frequencies in the ratio 4:1:1, used to digitize the luminance and color difference
components (Y, R-Y, B-Y) of a video signal. The four represents 13.5 MHz, the sampling frequency of Y, and the ones each 3.75
MHz for R-Y and B-Y
4:2:0 - a sampling system used to digitize the luminance and color difference components (Y, R-Y, B-Y) of a video signal.
The four represents the 13.5 MHz sampling frequency of Y, while the R-Y and B-Y are sampled at 6.75 MHz-effectively between
every other line only (one line is sampled at 4:0:0, luminance only, and the next at 4:2:2)
5C - see Digital Transmission Content Protection
A:B:C notation - the a:b:c notation for sampling ratios, as found in the CCIR-601 specifications, has the following meaning:
4:2:2 means 2:1 horizontal downsampling, no vertical downsampling. (Think 4 Y samples for every 2 Cb and 2 Cr samples in a
scanline.)4:1:1 ought to mean 4:1 horizontal downsampling, no vertical. Downsampling (Think 4 Y samples for every 1 Cb and 1 Cr
samples in a scanline.) It is often misused to mean the same as 4:2:0.4:2:0 means 2:1 horizontal and 2:1 vertical downsampling.
(Think 4 Y samples for every Cb and Cr samples in a scanline.)Not only is this notation not internally consistent, but it is
incapable of being extended to represent any unusual sampling ratios, eg different ratios for the Cb and Cr channels
ABR - ABR stands for Average Bitrrate and is basically just one form of Variable Bitrate where the encoder tries to maintain specific
average bitrate for the file so that the actual size of the resulting file could be estimated more easily. To achieve a situation where you
tell the encoder that you wish to use a specific ABR and that the encoder would actually do exactly that requires usage of multi-pass encoding
technology. As there aren't currently any audio encoders available that can use multi-pass encoding, true respect-the-ABR-I-want-to type of
encoding is possible only with video encoding. On the other hand, ABR can also simply state the average bitrate of a VBR encoded video
or audio clip
AC coefficient - any DCT coefficient for which the frequency in one or both dimensions is non-zero
Arithmetic Coding - perhaps the major drawback to each of the Huffman encoding techniques is their poor performance when
processing texts where one symbol has a probability of occurrence approaching unity. Although the entropy associated with such
symbols is extremely low, each symbol must still be encoded as a discrete value.Arithmetic coding removes this restriction by
representing messages as intervals of the real numbers between 0 and 1. Initially, the range of values for coding a text is the
entire interval [0, 1]. As encoding proceeds, this range narrows while the number of bits required to represent it expands.
Frequently occurring characters reduce the range less than characters occurring infrequently, and thus add fewer bits to the
length of an encoded message
ASF (Advanced Streaming Format) - ASF is a highly compressed file format that contains streaming video, audio. When an ASF file is palyed
back, content is deliverd to you as a continuous flow of data. You no longer have to wait for the whole video and audio file to fully download
before you start to view them. So, this file format is specially designed to run on networks. When an AVI file is compressed and converted to
an .asf file, the file begins playing after only a few seconds. ASF files can be played back with the Windows Media Player (provided the
appropriate codecs are installed), streamed with Windows Media Services or optionally packaged with Windows Media Rights Manager. You can
click here to find more information about ASF format and view ASF to MP3 Converter and ASF to AVI MPEG Converter
ASP (Advanced Simple Profile) - Advanced Simple Profile is one of the video encoding layers of MPEG-4. It is best understood as an
addition to MPEG-4's Simple Profile video encoding. ASP adds the following technologies over SP, but is otherwise exactly like SP:
B-frames, Q-pel motion compensation, extra quantization tables and global motion compensation
Aspect ratio - There are currently two standard TV aspect ratios in the U.S., 1.33 (4:3) and 1.78 (16:9). The 1.52 aspect ratio set is sort
of a compromise in the transition from one system to another. They alter picture geometry to get either 1.33 or 1.78 to show up on the 1.52 screen.
In the DTV world we’ll see a bit of 1.55 or 14:9 as another option in the compromise. That’s what will be done to 1.33 images as they are
upconverted to a raster that is defined as 1.78. Some of the top and bottom of the 1.33 image will be cut off so that the image can appear to be
wider on the 1.78 set. There will still be slight black bars on the left and right edges of the image.
Several manufacturers are advocating 1.85 because it's a common aspect ratio for many American movies. The Director's Guild has called for a study
of making 2:1 the shape of new video displays. It is also possible that some day the high definition active picture area will be redefined as 2.35
from its current 1.78 aspect ratio. This is just another extension of defining the 1.33 aspect ratio of standard definition television to 1.78 in
the DVD format.
If the future of television is widescreen, is one aspect ratio better than another? Knowing that we will have to accommodate the 1.33 aspect ratio
for some time to come, the question becomes how wide can we go and still deal with the 1.33 image in the center? The resolution of current display
technology would suggest that 1.78 is the upper limit of our current capability. The 1.33 image is compromised by only being able to use the
resolution in the center of the display and images wider than 1.78 can’t use the resolution available at the top and bottom of the display.
Some of these problems can be partially resolved by the use of high quality scalers and displays that far exceed the resolution of the source
signal. That gets tough to accomplish as the resolution of our source signals goes up. It looks as if the 1.78 imager has a long life ahead of
it as a compromise between 1.33 and all of the wider aspect ratio pictures
ASX (Advanced Stream Redirector) - An asx file is used to store information on servers and media files for streaming video and audio over the
Internet, such as multimedia web sites. The .asx file is a simple text file that contains server and media information, so you can easily find
out the name of the file and server address of the streaming content with a text editor
ASV (Audio Still Video) - A still picture on a DVD-Audio disc
ATSC (Advanced Television Standards Committee) - The technical group that defined the high definition TV standard for US terrestrial
transmission
audio/video codec - An audio/video codec is a computer program that compresses/decompresses digital audio/video data according to a
given audio/video file format or streaming audio/video format. Most codecs are implemented as libraries which interface to one or more
multimedia players, such as VLC, Winamp or Windows Media Player
Audio/Video compression - is a form of data compression designed to reduce the size of audio/video data files. Audio/Video compression
algorithms are typically referred to as audio/video codecs. As with other specific forms of data compression, there exist many algorithms
to achieve the compression effect
Audio/video editing - audio/video editing is the process of taking recorded sound and changing it directly on the recording medium
Audio/video effects - sound/visual effects or audio/video effects are artificially created or enhanced sounds/visuals, or sound/visual
processes used to emphasize artistic or other content of movies, video games, music, or other media
Audio/video filters - An audio/video filter is a type of filter used for processing audio/video signals. Many types of filters exist for
applications including graphic equalizers, synthesizers, sound effects, CD players and virtual reality systems
Audio/video format - An audio/video format is a medium for storing audio and video. The term is applied to both the physical medium and
the format of the content - in computer science it is often limited to the file format, but its wider use usually refers to the physical
method used to store the data
AUDIO_TS - If you look at the files on a DVD, you will notice that most DVDs have both a VIDEO_TS and AUDIO_TS folder, but the AUDIO_TS
folder is usually empty. DVD-Audio would be stored in an AUDIO_TS folder but is a separate format to DVD-Video
Authentication - Before a movie can be played the player and the disc have to establish a secured communication line on which they can
transfer the actual movie. Before they can establish that line they need to make sure that the right "person" is on the other side - this
is done via several key exchanges, verifications, etc.
Authoring - Authoring means, in video world, a process where already-encoded video files are transferred into a specific format that
describes how the data should be kept on storage media, such as CD or DVD. Most common use of the term is when speaking of DVD authoring,
using a separate DVD authoring software that allows users to create menus, chapter selections, etc to the disc's layout in addition to the
actual video file(s) and transfer this structure to filesystem that can then be burned to a DVD. Other authoring processes include VCD
authoring and SVCD authoring. In both processes, authors can create menus and chapter selections and various other tasks before the structure
is ready for CD burning, pretty much like in DVD authoring (just in more limited scale)
AVC (Advanced Video Codec) - Otherwise known as MPEG4, part 10 this is the codec that most of the world's broadcasters are moving to
for HD transmissions
AVI (Audio/Video Interleaved) - A file format for storing and playing back movie clips with sound on Windows-based PCs. An AVI file is
organized into alternating ("interleaved") chunks of audio and video data. AVI is a container format, meaning that it specifies how the data
will be organized, but is not itself a form of audio or video compression.
AVI is the type of file that's created when DV clips are imported from a digital camcorder to a PC. (These clips are often referred to as
"DV-AVIs" because they contain full-quality digital video content.)
B-Y R-Y - The human visual system has much less acuity for spatial variation of colour than for brightness. Rather than conveying RGB,
it is advantageous to convey luma in one channel, and colour information that has had luma removed in the two other channels. In an analog system,
the two colour channels can have less bandwidth, typically one-third that of luma.
In a digital system each of the two colour channels can have considerably less data rate (or data capacity) than luma.
Green dominates the luma channel: about 59% of the luma signal comprises green information.
Therefore it is sensible, and advantageous for signal-to-noise reasons, to base the two colour channels on blue and red.
The simplest way to remove luma from each of these is to subtract it to form the difference between a primary colour and luma.
Hence, the basic video colour-difference pair is (B-Y), (R-Y) [pronounced "B minus Y, R minus Y"].The (B-Y) signal reaches its extreme values
at blue (R=0, G=0, B=1; Y=0.114; B-Y=+0.886) and at yellow (R=1, G=1, B=0; Y=0.886; B-Y=-0.886).
Similarly, the extrema of (R-Y), +-0.701, occur at red and cyan. These are inconvenient values for both digital and analog systems.
The colour spaces YPbPr, YCbCr, PhotoYCC and YUV are simply scaled versions of (Y, B-Y, R-Y) that place the extrema of the colour difference
channels at more convenient values
Baseband - video and audio signals are considered to be "prime", or baseband. Video and audio can be broken down into more
basic elements, but those elements no longer constitute the desired signal as a single element. Baseband video and audio signals
are often AM or FM modulated onto a carrier frequency, so that more than one set of "prime" signals can be transmitted or
recorded at the same time
BetaMax - "The better format". You can still hear this from people who used to have BetaMax videos in 1980s and who are now forced to move
to VHS compatible VCRs or to digital VCRs because lack of blank tapes, etc...
BetaMax was developed in 1970's by Sony to offer consumers the
same possibility for video recording as they did have for audio recording. BetaMax was the first one to offer certain functions that we nowadays
take as granted -- they provided first HiFi videos, first "tape remaining" counters, peek search, Automatic Program Search (in VHS systems
nowadays called as "indexing"), etc...
BetaMax also had better resolution than rival formats, because it used more tape for each second than
other formats. This was also the flaw that eventually gave VHS the winning edge -- American consumers didn't give a shit about quality of their
recordings, but instead they wanted to fit as much video as possible into one tape. In Europe currently all the VHS systems have SP/LP options
that allows you to choose double recording time (and obvisouly, reduced quality) -- in U.S. all the VCRs have also XP or EP option that allows
users to fit triple the recording time to one tape (means: already crappy VHS quality/resolution is divided by three).
BetaMax and its "big brother", BetaCam, are nowadays de facto in professional TV companies, producing companies and other video editing companies,
although digital video is finally killing this format (just like it is killing all the other analogue formats), but that will take many, many years.
For more information about BetaMax, please check out this site
Bicubic filtering - Resampling method which usually gives better results than bilinear filtering. Bicubic uses a 4x4 area instead of the
2x2 that bilinear uses, and maps cubic functions to the points instead of lines. Bicubic filtering is especially better at blowing up images,
as opposed to shrinking them
Bilinear filtering - A better way to process images when they must be sub- or supersampled. The fastest way to sample an image is to pick
the closest pixel to the point being examined; bilinear filtering improves on this by grabbing the four closest pixels and adding them together
in a weighted average, based on how close the point is to each of the four pixels. Bilinear filtering is most commonly associated with image
resizing and texture mapping
BIN - is an image from a CD. Great for distributing a VCD on the web. BIN is the main file to create VCD by burning it to CD-R(W) with a
burn program
Bit Budget - the total amount of bits available on the media being used. In DVD, the bit budget of a single DVD-R disk is
approximately 4.7 GB
Bitrate - With audio compression, the average amount of data required to store one second of music (expressed in kilobits per second, or
Kbps). Some codecs like MP3, WMA, and AAC allow files to be encoded at different bitrates. Generally, as bitrate decreases, so does the sound
quality of the resulting file, as well as the amount of memory required to store it
Black & White - monochrome or luminance information. Monochrome means one color. In the color television system the Black &
White portion of the picture has to be one "color"; gray, D6500, 6500°K as defined by x and y values in the 1931 CIE color
coordinate system. The black and white signal in the S or Component video path is separate from the color information
BMP (Windows Bitmap Image) - A standard format used for storing images on Windows-based PCs. BMP images can either be compressed or
uncompressed. This type of file also sometimes appears with the ".DIB" extension
BT.601 - See ITU-R BT.601-2
BT.656 - See ITU-R BT.656
BUP file - A bup file is a Back UP file of an IFO file. These files are commonly found on DVDs
B-VOP (Bi-directional VOP) - A frame (image) encoded by non-causal prediction relatively to previous or next frame
Byte aligned - a bit in a coded bitstream is byte-aligned if its position is a multiple of 8-bits from the first bit in
the stream
Cam - In this particular case, with Cam we mean a specific method how movie pirates create illegal bootleg copies of original movies.
Cam method is basically just a guy who uses either regular or professional camcorder to shoot the movie either from TV or actually inside
a movie theatre (in some Cam copies of movies you can actually see audience as well :-). These bootleg copies are normally then encoded
into VCD, SVCD or DivX format and distributed illegally over the Internet
CATV (Community Antenna Television) - Cable TV - In its early form cable television was an antenna system that served a community
CBR (Constant Bit Rate) - Basically it is a term that describes how video or audio is encoded -- constant bitrate means that the bitrate
doesn't vary during the video or audio at all, but is same through the clip. CBR bitrates are very easy to use in calculations -- if you have
an MP3 file that has CBR of 128kbit/sec and it lasts for 3 minutes, the amount of HDD space it takes can be calculated easily:
128kbit = 128 x 1024 bits
1 byte = 8 bits
1 kilobyte = 1024 bytes
1 megabyte = 1024 kilobytes
3 minutes = 180 seconds
180 x 128 x 1024 / 8 / 1024 / 1024 = 2.81MB
Cell (ID) - A cell is the smallest video unit on a DVD. Normally used to contain a chapter it can also be used to contain a smaller unit
in case of multiangles or seamless branching titles
CGA (Color Graphics Adapter) - First color-graphics standard for PC platform, developed by IBM back in 1981. Offered a resolution of 300x200
and four colors
Channel Coding - Data encoding and error correction techniques used to protect the integrity of data that is being transported through
a channel. Typically used in channels with high bit error rates such as terrestrial and satellite broadcast and videotape recording
Chroma Bandpass - In a NTSC or PAL video signal, the luma (black and white) and the chroma (color) information are combined together.
If you want to decode an NTSC or PAL video signal, the luma and chroma must be separated. A chroma bandpass filter removes the luma from
the video signal, leaving the chroma relatively intact
Chrominance - The color of an area, ignoring its brightness (luminance)
Chrominance subsampling - Encoding chrominance information at a lower resolution than luminance information, due to the fact that the human
eye senses brightness detail better than color detail. Chrominance subsampling is often the first step in video compression, since it cuts out
a good part of the data without sacrificing much quality. MPEG uses 2:1 subsampling in both horizontal and vertical directions, cutting out 25%
of the data. Each 2x2 square of pixels thus has its own brightness, but share the same color. Intel Indeo goes farther, using 4:1 subsampling in
each direction, cutting out 43% of the data. Chrominance subsampling is the major reason high-quality video codecs are often cause “color bleeding”
around sharp edges of computer generated video
CMS (Content Management System) - A content management system (CMS) is a computer software system for organizing and facilitating
collaborative creation of documents and other content
Codec (COder/DECoder) - Short for compressor / decompressor, a codec is any technology for compressing and decompressing data. Basically
it is a piece of software or a driver that adds a support for certain video/audio format for your operating system. With codec, your system
recognizes the format the codec is built for and allows you to play the audio/video file (=decode) or in some cases, to change another
audio/video file into that format (=(en)code). The word "codec" is a portmanteau of any of the following: 'Compressor-Decompressor',
'Coder-Decoder', or 'Compression/Decompression algorithm'. Codecs encode a stream or signal for transmission, storage or encryption and decode
it for viewing or editing
Color Component - See Color Difference
Color Difference - All of the color spaces used in color video require three components. These might be R'G'B', Y'IQ,
Y'UV or Y'(R' - Y')(B' - Y'). In the Y’ (R' - Y')(B' - Y') color space, the R' - Y' and B' - Y' components are often referred
to as color difference signals for obvious reasons. They are made by subtracting the luma (Y') from the red and blue components.
I and Q and U and V are also color difference signals since they are scaled versions of R' - Y' and B' - Y'. All the Ys in each
of the Y'IQ, Y'UV and Y'(R' - Y')(B' - Y') are basically the same, although they are slightly different between SDTV and HDTV
Color Space - The color range between specified references. Typically references are quoted in television: RGB, Y, R-Y,
B-Y, YIQ, YUV and Hue Saturation and Luminance (HSL). Moving pictures between these are possible but require careful attention
to the accuracy of processing involved. Operating across the media--print, film and TV, as well as between computers and TV
equipment will require conversions in color space
Color Space Conversion - The translation of color value from one color space to another. Since different media types, like
video and computer graphics, use different color spaces, color space is often performed on the fly by graphics hardware
Component Digital - A digital representation of a component analog signal set, most often Y, B-Y, R-Y
Composite Digital - A digitally encoded video signal, such as NTSC or PAL video that includes horizontal and vertical
synchronizing information. A digital representation of a component analog signal set, most often Y, B-Y, R-Y
Compression Artifacts - Compacting of a digital signal, particularly when a high compression ratio is used may result in
small errors or "artifacts" when the signal is decompressed
Conditional Access - Digital video signals can be scrambled in such a way that a conventional decoder cannot understand them.
Only when unscrambled by a special system can the viewer see the original. This allows capability to add new services like
Container - A container is, like the name says, a construct to contain data - in this case video and audio date and possibly subtitles
and navigational information. For instance, you would like to put a soundless video stream and the audio track together in one file. To do
that you need a container format. Examples of container formats are: AVI, ASF, OGM, Quicktime, VOB and MPG
Container format - A container format is one that holds different kinds of data within its file. Container formats, such as RealAudio and
TIFF, are gaining in popularity because of their multimedia applications, as well as their cross-platform compatibility. For example, a single
container file can hold chapter information, hyperlinks and subtitles, as well as different kinds of codecs that enable various types of
players to read the file
CSS (Content Scrambling System) - In DVD-Video, an encryption scheme designed to protect copyrighted material that resides on a disc by
periodically scrambling the data using encryption keys. A tool named Decss can allow users to circumvent it. Although Decss didn't exactly
crack the CSS, but instead used leaked decryption keys
DAR - stands for Display Aspect Ratio and indicates the dimension of a screen. Most PC screens have a DAR of 4:3, meaning that the
horizontal size is 4/3 as large as the vertical size. For TVs we have a lot of old 4:3 displays and more and more 16:9 displays. As you
can guess from the numbers 16:9 displays are broader than 4:3 displays having the same diagonal size. 16:9 screens are more suited to
display Hollywood movies which are usually shot with an aspect ratio of 1:2.35 or 1:1.85 (meaning that the horizontal size of the picture
is 1.85 times as wide as the vertical size)
DAT - DAT can mean lots of things -- often it is used to refer to a certain tape backup format. In a/v terminology it normally refers
(at least most questions are focused on this one) to files that VideoCD has in its SEGMENT or MPEGAV directiories. These DAT files are
basically MPEG-1 files with an additional information and certain specific file structure -- they are NOT "real" MPEG-1 files and you need
to convert them back to "real" MPEG-1 files in order to edit them even that most of the software players treat them as regular MPEG-1 files
DCT - Discrete Cosine Transform is used for JPEG and MPEG
Decimation Filter - a decimation filter is a low pass filter designed to provide decimation without the aliasing artifacts
associated with simply throwing data away
Deinterlace - The process of restoring a progressive video stream out of an interlaced one is called deinterlacing
Demultiplexing - The opposite of multiplexing. In this process a combined audio/video stream will be separated into the number of streams
it consists of (a video stream, at least one audio stream and a navigational stream). Every VOB encoder demultiplexes the VOB files before
encoding (FlaskMpeg, mpeg2avi, dvd2mpg, ReMpeg2) and every DVD player does the same (audio and video are being treated by different circuits,
or decoded by different filters on a PC)
Demux - Demuxing / demultiplexing basically means, when speaking of video formats, splitting the file that contains both audio and video
data (and possible other data streams as well, like subtitles), into separate files, each containing one element of the original file.
Demuxing file doesn't weaken the video nor audio quality, it doesn't do anything for these data streams, it just simply saves them into
separate files. Opposite of demux is muxing, which basically joins the datastreams back together
Depth of Focus - see Depth of Field
Descrambling - DVDs are usually CSS scrambled - imagine you decide to give a number to each letter, starting with 1 for a, etc. A sentence
would become a couple of digits - that's what we call scrambled. Of course CSS is much better than that but it's still quite easy to crack.
Descrambling means reversing the scrambling process, rendering our digits to a sentence again, or making our movie playable again - you can
try to copy a movie to your hard disk when you've authenticated your DVD drive and play it, you'll get a garbled picture because it's still
scrambled. Common CSS descramblers either use a pool of known descrambling keys (DeCSS or DODSrip - they contain a large number of keys but
not all of them) or try to derive the key by a cryptographic attack (VobDec - that's why it works on most disc since it's not dependent on
a pool of discs)
Descrambling - DVDs are usually CSS scrambled - imagine you decide to give a number to each letter, starting with 1 for a, etc. A sentence
would become a couple of digits - that's what we call scrambled. Of course CSS is much better than that but it's still quite easy to crack.
Descrambling means reversing the scrambling process, rendering our digits to a sentence again, or making our movie playable again - you can
try to copy a movie to your hard disk when you've authenticated your DVD drive and play it, you'll get a garbled picture because it's still
scrambled. Common CSS descramblers either use a pool of known descrambling keys (DeCSS or DODSrip - they contain a large number of keys but
not all of them) or try to derive the key by a cryptographic attack (VobDec - that's why it works on most disc since it's not dependent on a
pool of discs)
Digital8 - Digital camcorder tape format developed by Sony. Uses the same cassettes as analog Hi8 format, just digitally
DirectX - DirectX is an application program interface developed by Microsoft, first for Windows 95, for creating and managing graphic images
and multimedia effects in applications such as games and active Web pages. It includes the DirectDraw API for direct access to video memory
Digital Video (DV) - Digital video is usually compressed since it'd take Terabytes - thousands of Gigabytes or for the mathematicians among
you : 10^12 Bytes) to store a movie uncompressed. Since standard loss less compression is insufficient for video, the video codecs have to
get rid of unimportant information - stuff the human eye won't see or is unlikely to see. Since that is still not enough modern compression
algorithms use keyframes, I and P frames in order to save space
DivX ;-) - DivX ;-) was developed by bunch of hackers, most notably a guy called gej and it is based on Microsoft's version of MPEG-4
encoding technology, called as Windows Media Video V3. Basically Microsoft's encoders didn't allow users to save MPEG-4 streams into AVI
structure format, but forced users to use ASF instead. It also had some other limitations -- and those limitations were overriden in DivX ;-).
It also added a support for other than Windows Media Audio audio encoding technology, allowing users to have MP3 audio on their movies.
In 2001, original "developers" of this hacked (and therefor illegal) codec released a new legal version of DivX ;-), called DivX (without
smiley). DivX (without smiley) supports old DivX ;-) movies and also adds new features and better compression quality than "original" DivX ;-).
The name, DivX ;-), comes from now defunct CircuitCity pay-per-view DVD format called DIVX. With DivX ;-), you can store 50-120 minutes of
relatively good quality video to one CD (740MB) (==most of the movies can be stored in one CD, unlike in VCD or SVCD). Only negative aspect
DivX ;-) has when it's compared to VCD is the fact that VCDs can be played with regular stand-alone DVD players and DivXs can't
DivX - DivX was developed by DivX, Inc., to compress a great deal of video content into relatively small files and still retain reasonably
good image quality when played back. DivX is based on MPEG-4, and is a popular choice for sending video files over the Internet
DIVX (original) - Now de-funct pay-per-view version of DVD-Video standard developed by Circuit City, an American consumer electronics
retailer. System was developed to compete against DVD-Video format. Each movie disc had to be activated and each playback worked pretty
much like a movie rental -- the player "dialed" to CircuitCity's servers when movie was being watched and checked if user had any "credits"
left to watch the movie. If not, device would allow user to purchase more credits to watch the movie
DMCA - An American legislation, called Digital Millennium Copyrights Act that outlaws distribution, sale, use and advertising of tools
that allow circumventing copy protection mechanisms. Legislation also includes various other amendments to existing copyright legislation,
such as "cease and desist" letter format for copyright holders when they wish to warn a website that hosts material on their site that
violates copyright holder's rights
DMDK (Digital Media Development Kit) - generic name for an ATEME family of development boards such as DMDK 642
DRC - Dynamic Range Compression. AC3 Tracks contain a much larger dynamic range that most audio equipment can handle, therefore most
standalone and software DVD player will compress the dynamic range somewhat, according to the actual dynamic range. In layman terms the
volume will be augmented dymanically, e.g. explosions won't become louder or only a bit louder, whereas in normal dialogues the volume will
be augmented quite a bit. Since your player will do the same this is the way to go to have augmented volume
DMEK (Digital Media Evaluation Kit) - generic name for an ATEME family of development boards such as DMEK 6414, DMEK 642
DMIF (Delivery Multimedia Integration Framework) - transparent control interface and procedures for the delivery of MPEG
streams irrespective of the source site being a remote interactive terminal on a network broadcast or file system
DRM - DRM stands for Digital Rights Management and it is now (spring 2002) the hot topic among content owners and technology companies alike.
DRM doesn't mean just basic copy-protection of digital content (like ebooks, MP3s or DivX videos), but it basically means full protection for
digital content, ranging from delivery to end user's ways to use the content. If we speak about music DRM, companies wish to develop a product
which would allow record labels to sell copy-protected audio tracks over the Internet, so that only the buyer could be allowed to listen the
tracks. This is technically difficult, because traditionally, national laws require content owners like record labels, to grant "fair use"
rights for products consumers buy. This means that user has to be allowed to make personal copies of the purchased music, in order to use the
music in car, in portable digital audio player, in his/her laptop computer, etc. So, somehow DRM system needs to know when the copying is
allowed and when not -- users also have rights to make copies to their closest relatives, etc. So, normally this has been solved by allowing
"hops" -- original file can be copied, but the copy of the original file cannot be copied any further. Obviously this also causes problems,
if user accidentally deletes the original file, but still has the legal copy of the file :-)
DSM CC (Digital Storage Media Command and Control data) -
DTCP (Digital Transmission Content Protection) - an encryption method for protecting intellectual property of multimedia content
DTS (Digital Theater Systems Digital Sound) - DTS is a product of DTS, Inc., DTS is a multichannel audio compression format similar
to Dolby Digital/AC3 used in DVD-video discs, DVD-audio, 5.1 channel audio CDs, and some movie theaters. DTS differs from Dolby Digital
in that it generally uses higher data rates and many have the opinion that DTS is better quality. DTS can only be on a DVD-video disc if
accompanied by a Dolby Digital or LPCM track (for North America ) or mpeg audio and LPCM (European Community) to ensure compatibility,
because DVD players are only required to decode those standards in those regions
DTTR (Digital Television Tape Recorder) - see Digital Video Tape Recorder
DTV - DTV stands for Digital Television, which simply defines that the broadcast signal is being transmitted in digital form (normally
in either MPEG-2 or MPEG-1 format). The term itself doesn't define how the signal is being transmitted or which resolution it should use. In
"real life", Europe has chosen to use existing PAL resolution in digital broadcasting, but Americans and most notably Japanese, have opted
to use the "subset" of DTV, called HDTV in their broadcasts which offers native 16:9 aspect ratio and higher video resolution. In Europe,
three transmission standards are being used, DVB-T, DVB-C and DVB-S
DV (Digital Video) - DV is the format used by many digital camcorders, usually on Mini DV cassettes. Though the DV format employs a form
of lossy video compression (applied in real-time as you record with your camera), it's still memory-intensive. When transferred to a computer,
a DV clip requires roughly 1 GB of storage per 5 minutes of video. (Clips are usually stored on the computer as QuickTime or .AVI files.)
Despite its use of compression, DV can provide a clean image with up to 520 lines of resolution. DV uses a type of compression known as
"intraframe" - that is, it encodes video at the full standard frame rate of 30 frames per second. This allows frame-by-frame editing. In
contrast, video codecs like MPEG1 or MPEG2 tend to handle a video sequence by reducing the number of full frames per second and encoding
the differences between frames, making precise editing more difficult. These are known as "interframe" forms of compression
DV (Digital Video) - DV - video captured to a PC from a digital camcorder. There are two methods of storing DV video data, that is, type-1
and type-2. Both are stored usually in AVI files. Any DV stored as type-1 cannot be used with VfW-based editors. Microsoft provides DV encoder
and decoder filters for DirectShow only, and will not provide support for encoding or decoding DV video data for VfW
DV Type-1 Method - The native DV interleaved stream that is produced and consumed in I/O with a DV device contains DV compressed video
and pulse code modulated (PCM) audio data. This single interleaved stream can be stored in an AVI file as "ivas" stream (for interleaved
video/audio stream). Microsoft refers to this format as a type-1 DV AVI file.
Because the type-1 format stores data as a single AVI stream, type-1 DV AVI files are not compatible with VfW. DirectShow, however, easily
handles type-1 data streams by routing the streams to a DV Splitter filter that produces a DV-encoded video stream and one or more PCM
audio streams for playback or subsequent processing
DV Type-2 Method - Interleaved DV data can also be split into a single video stream and one to four audio streams within an AVI file.
Microsoft refers to this format of storing DV data as type-2. This format has the advantage of being backward compatible with VfW, because
it contains a standard video stream and at least one standard audio stream.
The type-2 file format requires a small amount of additional processing to split and multiplex the DV stream during the functions of capture
and transmit to IEEE 1394 DV devices
DVB (Digital Video Broadcasting) - DVB Project is an industry organization that develops technologies for the digital TV. The three most
widely used DVB's transmission protocols are DVB-C, DVB-S and DVB-T. All of these digital platforms are widely used, although mostly in Europe.
DVB developes not just transmission protocols, but also interactive standards for digital TV set-top boxes, etc. Various other DVB's protocols
include MHP (multimedia home platform, also dubbed as DVB-MHP), DVB-M (standard for measuring DVB-S/T/C transmissions, etc), DVB-H (an "upgrade"
of DVB-T standard that would allow using terrestial network to deliver DVB-T digital stream to mobile devices), etc. DVB's homepage is
here
DVI (Digital Video Interface) - is a specification created by the Digital Display Working Group (DDWG). The DVI specification has
created an uniform connector that can accommodate both, digital and analog video signal. DVI has three subsets: DVI-A, for analog signals,
DVI-D, for digital signals, and DVI-I (integrated), for both analog and digital signals
DVI-A - see DVI instead
DVI-I (Digital Video Interface - Integrated) - DVI-I and means a DVI connector that can transmit both analog and digital video data
EL (Electro Luminescent) - display technology based on the same technology than the LED that show up on many electronic devices.
Allow building flat displays. Competitor for CTR, LCD and Plasma
Encode - Encoding is opposite of decoding. Encoding means that a file, whether it is an audio, video or picture file, is compressed to
another format that normally takes up less physical drive space than the previous format. Common video encoding methods are DivX, MPEG-1,
MPEG-2 and MPEG-4 -- most common audio encoding method or format is MP3
Encoding (Audio/Video) - The process of converting an audio/video file from one format to another using audio/video codecs
Encryption - the process of coding data so that a specific code or key is required to restore the original data. In broadcast,
this is used to make transmissions secure
Error Detection - checking for errors in data transmission. A calculation is made on the data being sent and the results are
sent along with it. The receiver then performs the same calculation and compares its results with those sent. If an error is
detected the affected data can be deleted and retransmitted, the error can be corrected or concealed, or it can simply be reported
ES (Elementary Stream) - An elementary stream is a single (video or audio) stream without container. For instance a basic MPEG-2 video
stream (.m2v or .mpv) is an MPEG-2 ES, and on the audio side we have AC3, MP2, etc files that are ES. Most DVD authoring program require
ES as input
Exif (EXchangeable Image File format) - Basically, Exif file format is the same as JPEG file format. Exif inserts some of image/digicam
information data and thumbnail image to JPEG in conformity to JPEG specification. Therefore you can view Exif format image files by JPEG
compliant Internet browser/Picture viewer/Photo retouch software etc. as a usual JPEG image files. Tiff files can have the same Exif data.
exif tags list
FastTrack - A decentralized P2P network that powers P2P applications such as Kazaa, Grokster and (at least partially as of now, Oct/2003)
iMesh. Used to be the backbone of Morpheus as well, but Morpheus switched to use Gnutella network instead in beginning of 2002
Field - Interlaced video streams contain fields rather than frames
FireWire - FireWire is a friendlier, "marketing" name for technology known as IEEE.1394. FireWire is basically a competitor to USB
technology, beating the original USB1.x hands down in transfer speeds, etc. FireWire is widely used in Apple computers and also virtually
all of the digital camcorders are equipped with FireWire ports. The technology is currently (03/2003) getting more and more popular in
Intel-based PCs as well
Firmware - Sort of a "operating system of the hardware", an embedded instruction set built-in or flashed into a hardware equipment, such
as a router, CDR drive, DVD-ROM drive, washing machine, etc
Forward compatibility - a new coding standard is forward compatible with an existing coding standard if new decoders
(designed to operate with the new coding standard) continue to be able to decode bitstreams of the existing coding standard
Forward motion vector - A motion vector that is used for motion compensation from a reference picture at an earlier time in
display order
FourCC - FourCC stands for four character code and is a code that uniquely identifies a video data stream format. A movie player will look
up the FourCC code then look for the codec associated to the FourCC code in order to play a certain video stream. A few examples: DIV3 = DivX
Low-Motion, DIV4 = DivX Fast-Motion, DIVX = DivX4
FTYP - is a four letter code (sometime including blanks) that is used to identify the "type" of encoding used, the "compatibility", or the
"intended usage" of a media file. It only pertains to MP4 or newer QuickTime (.mov) container file formats. It is somewhat analogous to the
so-called fourcc code, used for a similar purpose for media embedded in the AVI container format.
The four letter code "ftyp" itself is the atom type (in QuickTime terminology) or box type (in MP4 terminology). An atom/box with this label
contains data comprised of certain identifier(s). The table created for this website is an attempt to compile a list of all such identifiers
one might find
Frame - The basic source of a movie. One frame represents one image. A movie usually runs at 24 frames per seconds, so it has 24 different
images per second. Imagine 24 images with a bird on it, in the first image it's on the left, then it gradually movies somewhat to the right.
On the 24th frame the bird is on the right end of the image. Imagine these 24 images being played in sequence fast enough and it looks like
a bird would fly from left to right to the human eye
Framerate - Defines how many pictures eg. frames one second of video or audio contains, normally used acronym for framerate is fps -
frames per second. Human eye can't see picture changes after the framerate is more than ~24fps. In American TV system NTSC the framerate is
appx. 29.97fps and in European PAL system the framerate is 25fps
Frameserving - Frameserving is the process of sending a video frame from one application to another, without intermediary files. Say you
want to process an existing video in application A (for instance remove the black bars from the picture), and then encode it to another format
in application B. The traditional way is to export the video from application A to an imtermediary file. In order not to loose quality, you'd
have to use a lossless format (meaning huge files, about 100 GB for a 2h movie). You'd then import that intermediary video file into
application B. Frameserving allows you to export the video in uncompressed format frame by frame from application A, and import those frames
into application B, without the intermediary file. Popular ways to frameserve are AviSynth or VFAPI
Gamma - the transfer characteristics of most cameras and displays are nonlinear. For a display, a small change in amplitude
when the signal level is small produces a change in the display brightness level, but the same change in amplitude at a high
level will not produce the same magnitude of brightness change. This nonlinearity is known as gamma
Ghost Cancellation Reference - a reference signal on (M) NTSC scan lines 19 and 282 and (B, D, G, H, I) PAL scan line 318 that
allows the removal of ghosting from TVs
GIF (Graphic Interchange Format) - A format for storing digital images, commonly used for bullets, icons, and other graphics on the Web.
The GIF format is limited to 256 colors, so it's not as commonly used as JPEG for storing digital photos. A single GIF file can combine
several frames together for basic animated motion
H.221 - "Frame Structure for a 64 to 1920 Kbit/s Channel in Audiovisual Teleservices" defines the usage of P B-channels to transmit
multiplexed audio, video, other data and control signals
H.261 - "Video Codec for Audiovisual Services at P x 64 Kbit/s" has been known informally as "P x 64" because it defines video coding based
on P 64,000-bit per second channels. (P is typically two or more.)
H.263 - "Video Coding for Low Bit Rate Communication" is the coding method designed for H.324, using the techniques of H.261 plus significant
enhancements
H.264 - A new video encoding layer of MPEG-4, called nowadays officially as AVC. MPEG-4 itself contains various encoding methods, called
"subsets" or "layers", and the H.264 is a latest standardized layer in the MPEG-4 standard, launched in late 2002. Other MPEG-4 layers include
Simple Profile and Advanced Simple Profile that most MPEG-4 encoders nowadays use, including DivX and RealVideo 9
H.320 - "Narrowband Visual Telephone Systems and Terminal Equipment" is the summary ITU-T recommendation for standard videoconferencing using
ISDN or similar telephone circuits
H.323 - "Visual Telephone Systems and Terminal Equipment for Local Area Networks which Provide a Non-Guaranteed Quality of Service" (ver. 2 -
"Packet-based multimedia communication systems") is the summary ITU-T recommendation for standard videoconferencing with conventional local-area
networks
H.324 - "Terminal for Low Bit Rate Multimedia Communication" is the summary ITU-T recommendation for standard videoconferencing using POTS
HD (High Definition) - This refers to a video picture size higher than SD (see below) and typically one of the set of resolutions
defined by ATSC such as 1080i (1920x1080), 720p (1280x720) or 480p (720x480)
HDTV - HDTV stands for High-Definition Television and as its name suggests, it specifies a higher resolution to the viewable TV image than
the existing widely-used "standard" TV formats, such as NTSC and PAL. Term HDTV is very often confused with the term DTV which simply stands
for digital TV, but doesn't actually define higher resolution than the existing resolutions of PAL and NTSC. This "normal" DTV standard is
widely used in Europe with normal PAL resolution of 704x576. European-wide standardization of HDTV specs is still largely under discussion
and it is likely that Europe will switch to digital without actually changing the resolution to a higher one. The specified HDTV resolutions
that are used in United States and most notably in Japan, are called 1080i, 720p and 720i. HDTV's native aspect ratio is 16:9 -- same as with
anamoprhic DVD-Video discs, but in HDTV the resolution is "really" in 16:9 and not achieved by strecthing the pixels to be wider, like in
anamorphic DVD-Video discs
Hi8 - One of the best analog video camcorder formats, developed by Sony in late 1990's. Hi8 uses the same cassettes as Digital8 and normally
all D8 digital camcorders can also play Hi8 analog recordings
Horizontal Sync - this is the portion of the video signal that tells the display where to place the image in the left-to-right
dimension. The horizontal sync pulse tells the receiving system where the beginning of the new scan line is
HSI (Hue, Saturation and Intensity) -
HSync - see Horizontal Sync
HTT (Hyper Threading Technology) - Hyper-Threading Technology provides thread-level-parallelism (TLP) on each processor resulting in
increased utilization of processor execution resources. As a result, resource utilization yields higher processing throughput.
Hyper-Threading Technology is a form of simultaneous multi-threading technology (SMT) where multiple threads of software applications can
be run simultaneously on one processor. This is achieved by duplicating the architectural state on each processor, while sharing one set of
processor execution resources. Hyper-Threading Technology also delivers faster response times for multi-tasking workload environments. By
allowing the processor to use on-die resources that would otherwise have been idle, Hyper-Threading Technology provides a performance boost
on multi-threading and multi-tasking operations for the Intel NetBurst® microarchitecture. HTT optimizations of Morgan codecs increase
performance in the range of 15-30% (Average 22%). HTT capable: CPU - Intel (Pentium 4 HT, Xeon HT); Windows: versions (Windows NT/2000/2003
Server/XP, Vista)
HTTP (Hyper Text Transport Protocol) - Application layer protocol using TCP/IP communication protocol for requesting file.
Used between Web browser and web servers to request HTML pages and files
I and P Frames - Frame describing only the differences to the frame before (this is less than accurate but I think you'll get the picture
that way). Say we have a keyframe with a bird before a cloudy sky. Then we can use I frames which say something like this : move the bird an
inch to the left and one inch to the bottom
iDCT - The video information inside MPEG files is stored in the frequency domain rather than in the spatial domain (the images we see).
That way, the information gets compacted and that compactation can be used to compress (reduce) the amount of information you have to send
over the transmission channel. MPEG uses the DCT (Discrete Cosine Transform) to translate spatial information into frequency information.
To bring back the spatial information from the MPEG stream you have to apply the iDCT, that is, the Inverse Discrete Cosine Transform, that
undoes the DCT that was used during encoding.
DCT and iDCT are basically the same as DFT (discrete fourier transforms) but the results are integers rather than complex reals you get in
i/DFT. For more info please refer to a university-level book about DSP, communication systems or similar
IEK (Imaging Evaluation Kit) - generic name for an ATEME family of development boards such as IEK C6416
IETF - Internet Engineering Task Force - Organism that coordinates the normative works on the protocol and applications
concerning the Internet
IFO - In video editing, IFO normally refers to a file on DVD-Video disc and stands for InFOrmation. While the main content of DVD-Video disc
are the VOB files which contain the actual MPEG-2 audio, video and subtitle streams, the IFO files provide information for DVD player where
DVD-Video disc's chapters start, where certain audio tracks are located, etc..
IFPI (International Federation of the Phonographic Industry) - IFPI, the organization that represents music biz's big boys internationally,
while RIAA does the same job in the U.S. Virtually all western national copyright organizations (such as RIAA in States, Teosto in Finland,
etc) are members of IFPI
Interlace - Method of smoothening the video picture moving by having double the amount of frames than the video's fps value suggests.
Basically, how the interlacing is done, let's say in PAL format, is that each frame is split into two separate pictures, which both are
missing half of the picture information. The split is done by its horizontal lines. The PAL video contains 576 horizontal lines -- let's
say that the numbering of these lines begins from the top of the frame being the line number 1. The frame is being split to half-frame A and
half-frame B -- the half-frame A would contain lines 1, 3, 5, 7, ... and the half-frame B would contain horizontal lines 2, 4, 6, 8, 10, ...
So, when the video is shown with PAL that has frame frequency (fps) of 25fps, there are 50 "half frames" per second that are being updated.
First comes the first full frame's "half A" that fills horizontal lines 1, 3, 5, .. leaving other ones blank (assuming that we start from a
"zero state" that output doesn't have anything shown before we start counting this). Then comes first full frame's "half B" that fills the
missing lines 2, 4, 6, ... and leaves the existing "half A"'s lines showing as well -- now we have the frame no.1 fully shown on screen.
Then comes frame no.2's "half A" that then wipes off the frame no.1's "half A", but leaves the frame no.1's "half B" showing. So, now we
have a mixture where lines 1, 3, 5, 7, .. are being filled by frame no.2 and lines 2, 4, 6, .. are being filled by frame no.1
Interlaced - Interlaced is a video storage mode. An interlaced video stream doesn't contain frames (pictures as we know them) but fields
with each field containing half of the lines of one frame (all even or all odd lines). More info in video storage modes and interlacing can
be found in video basics
Interleaving - Imagine gluing together the audio and the video track at defined points, that's about it. The player will recognize the interleave
points and make sure that both audio and video are played in a manner that the "glued" points match through the movie.
A more detailed explanation: Imagine we have 10 seconds of video and 10 seconds of audio. Let each second of video be represented by a V and each
second of audio by an A. If you have an interleaving setting of 10 seconds the file on the disc will look like this: VVVVVVVVVVAAAAAAAAAA. Now if
you have an interleaving setting of 1 second instead here's what you get: VAVAVAVAVAVAVAVAVAVA
Inverse Telecine - The inverse of Telecine. Process where video editing tools reverse telecine process. Basically inverse telecine (or
IVTC as it is also called) brings back movie's original framerate from NTSC's 29.97fps to 24fps
ISO - Apart from being one of the leading standards organizations, ISO refers also to a CD or DVD image (not picture..) file with an
extension of .iso. Just like other CD/DVD image formats, ISO is a file that contains full content of the disc, including every single track,
directory, file and information about the structure of the disc (i.e. ISO files can't be used as they are, but they need to be either "mounted"
with tools like Daemon Tools or burned to CD or DVD in order to see what files the disc image actually contains). Normally ISO files are being
used to replicate existing CD/DVD discs, transfer those discs over the network to other location (or to other person) and burn back to CD/DVD
which then would be an identical replica of the original disc
"ISO" - "ISO" is a word derived from the Greek isos, meaning "equal". It is the root of the prefix "iso-", as in "isometric" (of equal
measure or dimensions) or "isonomy" (equality of laws, or of people before the law). The choice of "ISO" as the name for the organization
implies "equal" or "standard". It also avoids the plethora of acronyms resulting from the translation of the actual name of the organization,
"International Organization for Standardization". (It would be IOS in English and OIN in French; Organisation Internationale de Normalisation).
The International Organization for Standardization (ISO) is a worldwide federation of national standards bodies from some 130 countries, one from
each country. ISO is a non-governmental organization established in 1947. Its mission is to promote the development of standardization and related
activities in the world with a view to facilitating the international exchange of goods and services, and to developing cooperation in the spheres
of intellectual, scientific, technological and economic activity.
ISO's work results in international agreements that are published as International Standards.
The scope of ISO covers all technical fields except electrical and electronic engineering, which is the responsibility of IEC. A joint ISO/IEC
technical committee carries out the work in the field of information technology
ITU-R BT.601-2 - this international standard defines the encoding parameters of digital television for studios. It specifies
how analog video signal should be digitized, what sampling frequencies should be used, what range of values should be used for
luminance and chrominance components
ITU-R BT.656 - this international standard defines how synchronization information should be embedded into a BT.601 digital
video data stream
IVTC - See Inverse Telecine
JPEG (Joint Photographic Experts Group) - JPEG is a lossy codec for storing and transferring full-color digital images that's often used
to post photography and artwork on the Web. JPEG compression takes advantage of the human eye's inability to see minute color changes, removing
portions of data from the original picture file. When creating a JPEG file, varying amounts of compression can be selected, depending on the
desired file size and image quality
A form of this codec known as Motion JPEG is used by some digital cameras and camcorders for storing video clips of relatively small file size.
With Motion JPEG, each frame of video is captured separately and reduced in size using JPEG compression
JPEG XR - is the tentative name for a brand new JPEG format from Microsoft. Formerly referred to as the HD Photo file format, Microsoft
have now submitted it to the Joint Photographic Expert Group (JPEG). If approved, JPEG XR will offer better image fidelity, higher image
compression efficiency and flexible editing features
Keyframe - A complete frame but heavily compressed
Letterbox - Movies, for instance, are almost always made in widescreen format. A widescreen movie needs to be displayed on a screen with
different aspect ratio from the original film, the picture frame needs to be letterboxed. Letterboxing means adding black borders above and
below the original frame. The size of the borders depends on the difference between aspect ratios. For instance displaying a 2.35:1 widescreen
picture on a conventional 4:3 TV screen requires borders that cover 40 per cent of the screen.
See Henrik Herranen's page for a more in-depth explanation to
film to video conversions, and example images
Letterbox(ing) - The process of letterboxing consists of taking a movie frame (as shot by the camera of the camera guy on a Hollywood
movie set), resize it so that it fits on a 4:3 screen without stretching, then add black bars on top and bottom to fill the entire screen.
Here's a more visual explanation of the process
Level - a defined set of constraints on the values which may be taken by some parameters within a particular profile. A
profile may contain one or more levels
Live-streaming - Streaming media that is broadcast to many people at a same time. Also see: On-demand streaming
Lossless data compression - As the name implies, lossless compression retains all of the data of the original file as it's converted to a
smaller file size. When a lossless file such as a TIFF is opened, algorithms restore all compressed information, creating a duplicate of the
source file. Lossless compression is generally preferred for creating high-quality or professional-grade audio and video files where it's
important to retain fine detail
Lossy data compression - With this kind of compression, some of the source file's information is discarded to conserve space. When the
file is decompressed, this information is reconstructed through algorithms, usually resulting in some loss of sound quality or image detail
when compared to the original. Generally, the higher the resolution of the compressing file, the less the degradation. An MP3 file with a
resolution of 256 Kbps, for example, tends to sound more like the source file than one made at 64 Kbps
M-JPEG (Motion-JPEG) - M-JPEG is a video format that uses JPEG picture compression in each frame of the video. Frames of the video don't
interact with each other in any way (like they do in MPEG-1, MPEG-2, etc..) which results in much bigger filesize, but in other hand, it makes
the video editing easier because each of the frames has all of the information they need stored in them.
M-JPEG is used in very high quality video captures -- normally as the raw data format which is edited and compressed into another format after
the editing process is completed. Unfortunaly M-JPEG is not a standard or even standardized -- each vendor has their own codecs and normally
M-JPEG files created with one codec cannot be read with other vendor's codecs.
M-JPEG is the format that we recommend you to use in your video capture process as a raw data format. Editing this videostream is extremely
easy and encoding the edited M-JPEG stream into final format (such as MPEG-1, MPEG-2 or Divx ;-)) gives normally the best possible video quality
m1v/m2v - These two terms are used as extensions for MPEG-1 respectively MPEG-2 video data (video only, without any audio)
M3U - M3U was originally developed in late 1990s as a standard playlist format for MP3s, although its use has since then expanded beyond MP3s.
The .m3u files are basically just textfiles that list one MP3 or other media file on each line, normally with full path or URL to the file. If
the .m3u file is loaded to an MP3 player, the player normally plays the list of media files in the order they are listed in the playlist (unless
options such as "randomize" have been selected in the MP3 player)
M4IF (MPEG-4 Industry Forum) - It is an independent industry forum -- most of the companies working with digital video are members of this
industry body. M4IF defines the standards for MPEG-4 audio and video. It is a subsdiary of MPEG organization
Macroblock - The four 8 by 8 blocks of luminance data and the two (for 4:2:0 chroma format), four (for 4:2:2 chroma format) or eight (for
4:4:4 chroma format) corresponding 8 by 8 blocks of chrominance data coming from a 16 by 16 section of the luminance component of the picture.
Macroblock is sometimes used to refer to the pixel data and sometimes to the coded representation of the pixel values and other data elements
defined in the macroblock header. The usage should be clear from the context
Macrovision - American company that develops various copy-protection schemes for audio and video purposes. Is best known to have their
copy-protection mechanism for VHS tapes bundled with virtually every sold pre-recorded VHS tape in the world. Also, every DVD player sold in
the U.S. has Macrovision copy-protection mechanism built-in which prevents DVDs to be recorded to VHS cassettes without hacking either the DVD
player or the VCR. They have recently also developed various audio CD protection mechanisms and record labels have already introduced few
commercial audio CDs that have Macrovision's CDDA copy-protection mechanism
MC (Multipoint Controller) - An entity that provides for the control of three or more terminals in a multipoint conference
MD5 - MD5 is a data integrity validation mechanism, just like SFV and is used in similar ways. MD5 data is most commonly distributed as
separate .md5 files alongside the main file download files and can be used to check whether the download was complete and whether the data
remained uncorrupted during the download process.
MD5 data is created by a algorithm that examines the original file and creates a short(-ish) checksum data string out of the original file's
characteristics. When the file and the .md5 file are downloaded, the .md5 file can be used with a specific MD5 file checker application to
check whether the downloaded file is identical to the original file. If not, it typically means that the download is not complete or that
the downloaded file was corrupted during the data transfer
miniDV - is the most popular digital camcorder format at the moment. miniDV is a video cassette designed for use in miniDV digital
camcorders. The picture quality of digital video (DV) recorded on a miniDV cassette is basically identical or better to the quality of
DV recorded on a Hi8 or 8mm cassette by a Digital8 camcorder. miniDV can have up to 530 lines of video resolution for some camcorder
models. However, miniDV tapes are smaller which allows for smaller camcorders. miniDV tapes are available in lengths of 30 and 60
minutes (plus, recording in LP mode lets you extend total recording time with a 60-minute tape to 90 minutes)
MOV - .mov is a file extension used by the QuickTime-wrapped files. QuickTime Content (.mov, .qt), developed by Apple Computer, is a file
format for storing and playing back movies with sound. This flexible format isn't limited to Macintosh operating systems. It's also commonly
used in Windows systems, and other types of computing platforms. View MOV Converter
MP (Multipoint Processor) - An entity that provides for the processing of audio, video, and/or data streams in a multipoint conference.
The MP provides for the mixing, switching, transcoding, or other processing of media streams under the control of the MC
MP4 - MP4 is a new container format, a container format allows you to combine different multimedia streams into one single file.
Multimedia containers are for example the well known AVI, MPEG , Matroska, OGM. MP4 is the global file extension for the official container
format defined in the MPEG-4 standard. MP4 is streamable and supports all kinds of multimedia content, multiple audio-, video-,
subtitlestreams, pictures, variable-framerates, -bitrates, -samplerates...) and advanced content like 2D and 3D animated graphics, user
interactivity, DVD-like menus
MPAA (Movie Picture Association of America) - MPAA represents major movie studios in the U.S. Organization has pretty much the same kind of
role as music business's RIAA has -- it tries to fight against piracy, lobbies congressmen to extend laws that would limit "fair use" rights, etc.
MPEG (Motion Picture Expert Group) - a committee that sets international standards for the digital encoding of movies and sound. There
are several audio/video formats which bear this group's name. In addition to their popularity on the Internet, several MPEG formats are used
with different kinds of A/V gear:
MPEG1. This format is often used in digital cameras and camcorders to capture small, easily transferable video clips. It's also the
compression format used to create Video CDs, and commonly used for posting clips on the Internet. The well-known MP3 audio format (see definition
below) is part of the MPEG1 codec
MPEG2. Commercially produced DVD movies, home-recorded DVD discs, and most digital satellite TV broadcasts employ MPEG2 video compression to
deliver their high-quality picture. MPEG2 is also the form of lossy compression used by TiVo-based hard disk video recorders. It can rival the DV
format when it comes to picture quality. Because MPEG2 is a "heavier" form of compression that removes a larger portion of the original video signal
than DV, however, it's more difficult to edit with precision. The MPEG2 codec allows for selectable amounts of compression to be applied, which is
how home DVD recorders and hard disk video recorders can offer a range of recording speeds. MPEG2 is considered a container format
MPEG4. A flexible MPEG container format used for both streaming and downloadable Web content. It's the video format employed by a growing
number of camcorders and cameras
MPEG1 - MPEG1 format is often used in digital cameras and camcorders to capture small, easily transferable motion video clips. It
is also the compression format used to create Video CDs. In addition, The well-known MP3 audio format is part of the MPEG1 codec. View
DVD to MPEG1 Ripper
MPEG2 - MPEG2 format, a video standard developed by MPEG group, is often used in digital TVs, DVD movies and in SVCDs. It is not a
successor for MPEG1, but an addition instead. both of these formats have their own purposes in life. MPEG1 is meant for medium-bandwidth
usage and MPEG2 is meant for high-bandwidth/broadband usage. View DVD to SVCD Ripper
MPEG4 - MPEG4, the latest compression method standardized by MPEG group, is used for both streaming and downloadable web content,
and is also the video format employed by a growing number of portable video recorders. One of the best-known MPEG4 encoders is DivX
which since version 5 has been fully standard-compliant MPEG4 encoder. View DVD to MPEG4 Ripper and MPEG4 to MP3 Converter
MPEG7 - MPEG7 doesn't itself offer any new encoding features and it is not meant for representing audio/video content, unlike its
siblings MPEG1, MPEG2 and MPEG4. Instead, it offers metadata information for audio and video files, allowing searching and indexing of
audio/video data based on the information about the content instead of searching the actual content bitstream.
MPEG7 is based on XML and therefor is universal and all the existing tools that support XML parsing should be able to read the data as
well, provided that they can ignore binary parts of the file.
MPEG7 is not used at the moment, but it is under serious development and standardization process at the moment and hopefully we see
first fully featured MPEG-7 tools within few years
Multiangle - Multiangle is a special feature of the DVD format, allowing the viewer to switch between different views of the same scene.
For instance, let's assume your favorite sport on TV is hockey. You've certainly noticed that there are many cameras recording a hockey game.
And while the game is interrupted, you usually get to see slowmo scenes from different angles, be it of a goal scene, a foul or whatnot. While
watching the game on TV, you only get the see the picture from the camera that the guy in the cutting room wants you to see. Now, if you get
your favorite Stanley Cup final on DVD, the disc could include not only the game as seen on TV, but using the multiangle feature, contain the
games from all the different perspectives it was recorded from (camera from the ceiling, cameras on the side, cameras from behind the goal),
and while you're watching the game, you can press the Angle button on your remote to switch from one camera to another, or in DVD language,
switch from one angle to another, and that's what multiangles is all about
Multipass encoding - Before you read on: Currently true multipass encoding is available only for WM8 and MPEG-2 (SVCD & miniDVD). M4C is
not true multipass encoding (and read the M4C guide to find out what it is and how it works). An encoder that supports multipass will in a
first pass analyze the video stream to be encoded and write down a log about everything it encounters. Let's assume that we have a short clip
which starts out in a dialog scene where we have few cuts and the camera stays static. Then it leads over to a karate fight with lots of fast
cuts and a lot of action (people flying through the air, kicking, punching, etc). In regular CBR encoding every second gets more or less the
same bitrate (it's hard to stay 100% CBR but that's a detail) whereas in multipass VBR mode the encoder will use the bitrate according to its
knowledge about the video stream, that is the dialog part gets of the available bitrate and the fighting part gets more bitrate. The more
passes the more refined will the bitrate distribution be. In single pass VBR the encoder has to base his decisions on where to use how much
bitrate solely on the knowledge of the stuff it previously has encoded
Multiplexing - Usually video and audio are encoded separately. Then you have to join both of them to make a movie that you can play
(you can of course play audio and video separately in two players but to get synch would be rather hard). During multiplexing the audio
and video track are combined to one audio/video stream. The audio and video stream will be like woven together and navigational information
will be added so that the player can example fast forward/backward and still retain synch audio/video
Nearest neighbor - The quickest and dirtiest way to sample an image, particularly for resizing or texture mapping. When you need a pixel
that lies between ones you actually have, pick the closest one. This is fairly acceptable for integral enlargements, but looks bad when
shrinking images or when the scale values aren’t integers. On the other hand, nearest neighbor is extremely fast compared to bilinear or
bicubic methods
Normalizing - Normalizing consists of finding the volume peak of a soundtrack, then increase the rest of the soundtrack to the same level.
This is usually done at WAV level, that is all variables are integers so the precision is not as good as in DRC. Hence DRC is to be preferred
over Normalizing
NPT (Normal Play Time) - Indicates the stream absolute position relative to the beginning of the presentation. The timestamp consists of
a decimal fraction (logical equivalent of SMPTE time code). Temporal addressing scheme created for DSM-CC
NTSC (National Television System Committee) - NTSC is a color TV standard developed in the United States in 1953 by National Television
System Committee. NTSC is used in most of the American continent countries and in various Asian countries. Rest of the world uses either
some variety of PAL or SECAM standards. NTSC runs on 525 lines/frame and it's vertical frequency is 60Hz. NTSC's framerate is 29,97 frames/sec
NuppelVideo - NuppelVideo is a simple low consuming and fast capture program for bttv-cards and for the slower computers (200MHz)
with MMX capability. It uses the very fast RTjpeg2.0 codec. It has its own file format and a simple player, and is fast enough to
capture audio and video in real time. There is also a nuv2divx and a patched version of the well-known mpeg2_movie that can read
the *.nuv format and make nice movies from it.
OGM - OGM stands for OGg Media which is the name of the Ogg container implementation by Tobias Waldvogel. OGM can be used as an alternative
to the AVI container and it can contain Ogg Vorbis, MP3 and AC3 audio, all kinds of video formats, chapter information and subtitles
Overlay - Video overlay enables the display of full-motion video on monitor screen without the constraints of the video BUS speed.
The overlay can be either digital (eg. an .AVI-file or DVD-Video) or analog (eg. real-time NTSC or PAL video from a video capture board).
The analog signal is first decoded to a digital format by the capture board, stored into a frame buffer, and then fed directly to the graphics
processor's RAMDAC. When using video overlay the CPU does not have to process any of the video information saving valuable processing power for
actual applications
Oversampling - sampling data at a higher rate than normal to obtain more accurate results or to make it easier to sample
PAL - PAL, was introduced in the early 1960's in Europe , stands for Phase Alternating Line. It has better resolution than in NTSC,
having 625 lines/frame, but the framerate is slightly lower, being 25 frames/sec
PAL is used in most of the western European countries (except France, where SECAM is used instead), Australia, some countries of Africa,
some countries of South America and in some Asian countries
Pan & Scan - As you know from going to the movie theater, movies are not shot in the format of your traditional computer screen (I say
computers on purpose because in many European countries, the widescreen 16:9 TVs outsell traditional 4:3 format TVs these days - something
which is not yet the case for computer screens). When movies are prepared for DVD or video (especially video), they can be presented either
in the original widescreen 16:9 format, which leaves large black bars on top and bottom of the picture (but looks much better on widescreen
TVs), or the picture can be resized and cut at the sides so that it will fill a 4:3 screen. The process of turning the original widescreen
movie into one that fits your 4:3 screen is called pan & scan. For a more visual example on how pan & scan works, check out
this document
Picture - A source image or reconstructed data for a single frame or two interlaced fields. A picture consists of three rectangular matrices
of eight-bit numbers representing the luminance and two color difference signals
Picture Frequency - Film or video pictures are "flashed" on the screen. Film is a parallel format, where the entire film frame is flashed at
once. Video is a serial format, where the picture is usually drawn on the screen, one pixel at a time. Newer fixed array types of displays, such
as the DLP or D-ILA technology, are parallel imagers. Flashing information on a screen creates flicker. In basic terms, if the flicker rate is
fast enough light from the picture is perceive as steady. Depending on duty cycle and brightness of light, something in the order of 50 flashes
per second is the threshold of what many human beings consider steady. Something faster than that will improve perception of a steady state, up
to a point. In most light output conditions the upper limit is somewhere between 72 and 75 Herz
Pixel Clock - The pixel clock is used to divide the horizontal line of video into samples. The pixel clock has to be stable (a very small
amount of jitter) relative to the video or the image will not be stored correctly. The higher the frequency of the pixel clock, the more
samples per line there are
PGC - PGC stands for ProGram Chain. It is a term often used in DVD authoring and represents basically one concurrent playback item.
For instance the main movie has its own PGC, each trailer on a DVD usually has its own PGC. The studio logo that comes up when you enter
the disc has its own PGC, etc. Both SmartRipper in Movie mode and DVD Decrypter in IFO mode will show you all PGCs a DVD has. For more
info about PGCs visit MPUCoder's DVD information site. http://mpucoder.kewlhair.com/DVD/
Podcasting/Vodcasting - Podcasting is the method of distributing multimedia files, such as audio/video programs or music videos, over
the Internet using either the RSS or Atom syndication formats, for playback on mobile devices and personal computers. The term podcast,
like 'radio', can mean both the content and the method of delivery. The host or author of a podcast is often called a podcaster.
Podcasters' web sites may also offer direct download or streaming of their files; a podcast however is distinguished by its ability to be
downloaded automatically using software capable of reading RSS or Atom feeds. Podcasting with video files is called Vodcasting
Point-to-Multipoint - An arrangement, either permanent or temporary, in which the same data flows or is transferred from a single origin to
multiple destinations; the arrival of the data at all the destinations is expected to occur at the same time or nominally the same time
Predictor - A linear combination of previously decoded pixel values or data elements
Program Stream (PS) - A program stream is a combination of elementary video and audio streams (ES). An MPEG-1 program stream contains
MPEG-1 video and MPEG1 layer 2 audio (mp2) whereas an MPEG-2 program stream contains MPEG-2 video and MPEG1 layer 2 audio (mp2)
Progressive - Progressive or progressive scan is basically an opposite to interlaced picture. In standard, interlaced analog TV, the picture
on TV is changed 50 or 60 times (50Hz in Europe/PAL systems and 60Hz in most NTSC systems, including the American one), but the picture contains
only every other horizontal line and the line between is left "empty" -- and the next frame then contains only the horizontal lines missed in the
last frame. So, therefor in interlaced picture, at 50Hz frequency, the picture actually changes only 25 times per second (so its framerate is 25fps).
But in progressive scan technology, every picture contains everything, so therefor 50Hz progressive scan video changes the picture 50 times per
second, having the framerate of 50fps
PUO - PUO means Prohibited User Operations. It's a feature of the DVD format, allowing the person doing the authoring to prevent the
user from executing certain functionality. For instance, you could activate a PUO that prevents people from fast forwarding / skipping
an FBI warning before the main movie starts. Or, it could be used to force you to use the menu of the disc to change the audio language,
by setting the PUO for audio switching (so the audio button on your remote won't do anything)
QAM (Quadrature Amplitude Modulation) - This digital frequency modulation technique is primarily used for sending data downstream over a
coaxial cable network. 64QAM is efficient, supporting up to 28-Mbps peak transfer rates over a single 6 MHz channel. By comparison, 8-VSB will
only support about 19.5 Mbps in terrestrial broadcast applications. QAM's susceptibility to interfering signals makes it well suited to noisy
transmissions
QPSK (Quadrature Phase Shift Keying) - It is a digital frequency modulation technique used for sending data over coaxial cable networks.
Since it's both easy to implement and fairly resistant to noise, QPSK is used primarily for sending data from the cable subscriber upstream to
the Internet
Quantized DCT coefficients - DCT coefficients before dequantization. A variable length coded representation of quantized DCT coefficients
is stored as part of the compressed video bitstream
Quantizer - To truly understand this term you'd have to take a course in signal processing. In laymen's terms it means compression
factor. The higher this value the more compressed an image is (and therefore a high quantizer means low quality picture and small size
whereas low quantizers means high quality picture and larger size)
QuickTime - is a file format for storing and playing back movies with sound. Though developed and supported primarily by Apple,
Inc., this flexible format isn't limited to Macintosh operating systems - it's also commonly used in Windows systems and other types of
computing platforms. In Windows, QuickTime files usually appear with the ".MOV" filename extension
Since 2002, Apple has started using MPEG4 video encoding on its QT streams, producing much better, if not excellent, video quality. View
QuickTime Converter. View MOV to AVI MPEG Converter
R'-Y' - In video, the red-minus-luma signal, also called a color difference signal. When added to the luma (Y') signal, it produces the red
video signal
RA (Real Audio) - RA is a Real Media audio file extension, indicating a file readable by the RealOne Media Player. View RA to MP3 Converter
RAMDAC (Random Access Memory Digital-to-Analog Converter) - The part of the video card which converts digital intensity levels for RGB to
analog voltages sent to monitor. A DAC can have RAM to store look-up-table (LUT) information - hence RAMDAC. The speed of the RAMDAC (eg. 220,
250, 300, 350MHz) tells the maximum master clock rate, or video clock rate (VCLK) the image can be displayed at. You can calculate the maximum
refresh rate for a resolution using a simple formula: VCLK/(height*width) = refresh rate
RAW - An image file of minimally processed data received from a digital camera. Most camera manufacturers have their own proprietary
version of the RAW image format, and their own file suffixes. Canon, for example, uses ".crw" or ".cr2" for their version of RAW. Nikon's
RAW files end in ".nef," while Sony uses ".arw" and ".srf" suffixes.
Professionals prefer shooting in RAW because the additional information these large files contain allows greater flexibility in
post-production editing. Because the image is basically unprocessed (as compared to a JPEG image), RAW files can retain very subtle
color variations and fine detail. Color changes, contrast adjustments, and other manipulations of a RAW image yield significantly
fewer digital artifacts than the same changes made to a comparable JPEG file
RCE - RCE means Region Code Enhancement. Using the programming options that the DVD format offers (reading and writing to a number
of registers available in all players), RCE is a more advanced version of region codes. It's a way studios try to prevent you from
playing discs that are not sold in your region (don't have a matching region code). Old regionfree hardware players might have problems
with RCE discs, but most modern regionfree players have no trouble playing such discs. Currently, discs using RCE use RCE-3 but I don't
know if this means it's the 3rd version, or if the 3 has another meaning
RealMedia - One of the most popular formats for streaming content on the Internet, RealMedia includes the RealAudio codec for
sound clips and RealVideo codec for movies. RealAudio and RealVideo files are often given the common RealMedia ".RM" file extension.
RealMedia is a container format that's often heavily compressed for streaming over dial-up Internet connections. RealMedia variable
bitrate (RMVB) has been developed for VBR streaming files
RealVideo - RealVideo is a streaming video format developed by RealNetworks. RealVideo is probably the most popular streaming video
format in the world, although its quality is horrible if you compare it to MPEG4-based formats like DivX or WMV
Region codes - Region codes in this instance mean flags implemented in DVD-Video discs that determine the geographic area where the
DVD-Video disc is being sold and where it can be watched. These codes ensure that one country doesn't get a DVD movie before the same | | | |
