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Glossary about video format

  The following are some terms which you may often meet when using our product.

3G2 3GPP 4:3 Standard 16:9 Standard AAC


Aspect ratio AVI Bite Rate Codec DAT Deinterlacing DirectShow Encoder
FLV Frame Rate H.264 High Definition IFO ISO Letterbox M2TS


- The3rd Generation Partnership Project 2 (3GPP2) is a collaboration between telecommunications associations to make a globally applicable third generation 3G mobile phone system specification within the scope of the ITU's IMT-2000 project. In practice, 3GPP2 is the standardization group for CDMA2000, the set of 3G standards based on earlier 2G CDMA technology.

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

4:3 standard - The 4:3 ratio (generally named as: "Four-Three", "Four-by-Three" or "Four-to-Three") for standard television has been in use since television's origins and many computer monitors use the same aspect ratio. 4:3 is the aspect ratio defined by the Academy of Motion Picture Arts and Sciences as a standard after the advent of optical sound-on-film. By having TV match this aspect ratio, films previously photographed on film could be satisfactorily viewed on TV in the early days of the medium (i.e. the 1940s and the 1950s). When cinema attendance dropped, Hollywood created widescreen aspect ratios (such as the 1.85:1 ratio mentioned earlier) in order to differentiate their industry from the TV.

16:9 standard - 16:9 (generally named as: "Sixteen-Nine", "Sixteen-by-Nine" or "Sixteen-to-Nine") is the international standard format of HDTV as used in Australia, Canada, Japan, South Korea, and the United States, as well as in Europe on HDTV and non-HD widescreen television (EDTV) PALplus.

AAC - Stands for Advanced Audio Coder, is a standardized, lossy compression and encoding scheme for digital audio. Designed to be the successor of the MP3 format it has better sound quality and smaller size than MP3. Many mobile devices support AAC format like SonyEricsson's W890i, Sony's Walkman, Apple's iPhone, Nokia, Motorola, Samsung, BenQ-Siemens and Philips, BlackBerry, Nintendo's Wii, Creative Zen Portable, Microsoft Zune, (PSP) with firmware 2.0 or greater. An audio-encoding standard for MPEG-2 that is not backward, compatible with MPEG-1 audio.

AC3 - (Dolby Digital ac-3) is the common version containing up to six discrete channels of sound, with five channels for normal-range speakers (20 Hz – 20,000 Hz) (right front, center, left front, right rear and left rear) and one channel (20 Hz – 120 Hz) for the subwoofer driven low-frequency effects like explosion and hammerblow. Batman Returns was the first film to use Dolby Digital technology.

APE - (monkey's audio) A file with the extension .ape, is an audio file compressed using Monkey's Audio. Monkey's Audio is a lossless compression, which means it does not permanently discard data during compression. It achieves compression rates of around 40%. Since it is lossless, the quality of the audio after compression will be the exact same. And we can only convert the CD and uncompressed WAV to APE for the moment, MP3 is not available. Officially, Monkey's Audio is only available for the Microsoft Windows platform.

ASF - Stands for Advanced Streaming Format. Stores audio and video information and it is specially designed to run on networks like the Internet. ASF is a highly flexible and compressed format that contains streaming audio, video, slide shows, and synchronized events. When you use ASF files, content is delivered to you as a continuous flow of data. When an AVI file is compressed and converted to an ASF file, the file begins playing after only a few seconds.

Aspect Ratio - The aspect ratio of an image is its width divided by its height. Aspect ratios are mathematically expressed as x :y (pronounced "x-to-y") and x×y (pronounced "x-by-y"). The most common aspect ratios used today in the presentation of films in movie theaters are 1.85:1 and 2.39:1. Two common videographic aspect ratios are 4:3 (1.33:1), universal for standard-definition video formats, and 16:9 (1.78:1), universal to high-definition television and European digital television. Other cinema and video aspect ratios exist, but are used infrequently. In still camera photography, the most common aspect ratios are 4:3 and 3:2, though other aspect ratios, such as 5:4, 7:5, and 1:1 (square format), are used.

AVI - Stands for Audio Video Interleaved, storing sound and moving pictures in RIFF format developed by Microsoft. An AVI file can use different codec and formats so there is no set format for an AVI file unlike for example standard VCD video which sets a standard for resolution, bitrates, and codec used.

Bit Rate - Bitrate or Bit rate is the average number of bits that one second of video or audio data will consume. Higher bitrate means bigger file size and generally better video or audio quality while lower bitrate means lower file size but worse video or audio quality. Some bitrate examples in common video and audio files:
MP3 about 128 kbps (kilobits per second)
VCD about 1374 kbps
DVD about 4500 kbps
DV about 25 Mbps (megabits per second)

DAT - DAT 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 (their header data is slightly different when stored on VCD) 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.

DirectShow - DirectShow (sometimes abbreviated as DS or DShow), codename Quartz, is a multimedia framework and API produced by Microsoft for software developers to perform various operations with media files or streams. It is the replacement for Microsoft's earlier Video for Windows technology. Based on the Microsoft Windows Component Object Model (COM) framework, DirectShow provides a common interface for media across many programming languages, and is an extensible, filter-based framework that can render or record media files on demand at the behest of the user or developer. The DirectShow development tools and documentation were originally distributed as part of the DirectX SDK, however, they are currently distributed as part of the Windows SDK (formerly known as the Platform SDK).

Codec - A codec is a device or program capable of performing encoding and decoding on a digital data stream or signal. The word codec may be a combination of any of the following: 'Compressor-Decompressor', 'Coder-Decoder', or 'Compression/Decompression algorithm'.

Deinterlacing - Deinterlacing is the process of converting interlaced video, like common analog television signals, into a non-interlaced form.

Encoder - An encoder is a device used to change a signal (such as a bitstream) or data into a code. The code may serve any of a number of purposes such as compressing information for transmission or storage, encrypting or adding redundancies to the input code, or translating from one code to another.

FLV - SWF is not the only Flash format. FLV files (Flash Video Files) are a binary file format that delivers "bitmapped" video, limited to one video and one audio stream per file, over the Internet to the Macromedia Flash Player version 7. FLV content may also be associated with SWF files by ActionScript external references. FLV format can also be imported into Macromedia Flash Authoring tool. Unlike SWF format, FLV do not have maximum of 16000 frames limitation and ideally for large video file size.

Frame Rate - Frames per second. A measure of the rate at which pictures are shown for a motion video image. In NTSC and PAL video, each frame is made up of two interlaced fields.

H.264 - H.264 is known as MPEG4 AVC. The standard is expected to offer up to twice the compression of the current MPEG4 ASP (Advanced Simple Profile), in addition to improvements in perceptual quality. The H.264 standard can provide DVD-quality video at less than 1 Mbps, and is considered promising for full-motion video over wireless, satellite, and ADSL Internet connections.

High Definition - High Definition generally refers to the resolution of digital video, with resolutions of 1280x720 and 1920x1080 being the most common resolutions referred to as High Definition.

IFO - IFO is a DVD information file that stores information about Chapters, Subtitles and Audio Tracks. An IFO file is one of three types of files that are used on DVDs. It contains important navigational information, such as where a video chapter begins, and where audio and subtitle streams exist within the movie (VOB) file. IFO files are not encrypted.

ISO - An ISO image is an archive file (a.k.a. disk image) of an optical disc using a conventional ISO (International Organization for Standardization ) format that is supported by many software vendors. ISO image files typically have a file extension of .ISO but Mac OS X ISO images often have the extension ".CDR". The name "ISO" is taken from the ISO 9660 file system used with CD-ROM media but the term ISO image can refer to any optical disc image, even a UDF image.

Letterbox - Letterboxing is the practice of transferring widescreen film to video formats while preserving the film's original aspect ratio. On video displays with a 4:3 aspect ratio, the resulting videographic image has mattes (black bars) above and below it. LTBX is the identifying acronym for films and images so formatted. Letterboxing was developed for use in 4:3 television displays when widescreen television was in its technological infancy. Any Academy ratio (1.33:1) film will appear stretched and distorted to fill the widescreen television display, which is avoided by pillar boxing the image either via the television set or the DVD player. Occasionally, an image broadcast at 4:3 appears letterboxed on a 4:3, 16:9, or wider aspect ratio television screen. This effect is common on personal video websites and old documentaries.

M2TS - A .m2ts file is a Sony high definition video file type. M2ts files are rawAVCHD videos recorded using Sony's camcorders, such as the HDR-SR1 and HDR-SR5 models. Panasonic, Canon and other brands of AVCHD camcorders also record in m2ts format. M2ts files contain a transport stream BDAV MPEG-2. Each stream is its own file and file names are of the form XXXXX.M2TS (where "XXXXX" is a five-digit number followed by .M2TS).

M4A - The audio file format used by Apple in their popular iTunes Music Store often appears on your system with the ".M4A" filename extension. M4A can produce better audio quality than MP3 using less physical space for the files.

M4V - M4V is a standard file format for the popular Apple iPod devices.

MKV - The MKV format (Matroska Video) is an entirely free video format. More precisely, it is a container (hence the name Matroska, in reference to the Russian dolls contained within another) making it possible to contain video (DivX, Xvid, RV9, etc), sound (MP3, MP2, AC3, Ogg, AAC, DTS, PCM), as well as subtitles (SRT, ASS, SSA, USF, etc) in the same file.

MOV - QuickTime Content (.mov, .qt) a file format developed by Apple Computer to create, edit, publish, and view multimedia files. QuickTime supports video, animation, graphics, 3D and virtual reality (VR).

MP3 - is an acronym for MPEG-1 (or MPEG-2) Layer 3 audio encoding (it is not an acronym for MPEG-3). MP3 is a popular compression format used for audio files on computers and portable devices.

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-, subtitle streams, pictures, variable-frame rates, -bitrates, -samplerates...) and advanced content like 2D and 3D animated graphics, user interactivity, DVD-like menus.

MPEG - An ISO/ITU standard for compressing video offering lossy compression technique (some data of the original image is lost during the compression).

MPG - MPEG-1 or MPEG-2 encoded video file.

NTSC - Abbreviation of National Television Standards Committee. The NTSC is responsible for setting television and video standards in the United States (in Europe and other parts of the world, the dominant television standards are PAL and SECAM). The NTSC standard for television defines a composite video signal with a refresh rate of 60 fields (half-frames interlaced) per second. Each frame contains 525 lines and can contain 16 million different colors. The resolution of an NTSC VCD is 352x240 pixels, an NTSC SVCD is 480x480, and an NTSC full D1 DVD is 704 or 720 x 480.

OGG - OGG Theora is the video compression codec part of the ogg multimedia project. It is based on On2's VP3 codec, but On2 has released it now under a BSD type license and renounced its patents, so it is now free and open source. A final release is due out in early summer 2003. Ogg is the name of an open source multimedia project maintained by the foundation. OGG Vorbis refers to the lessee general purpose audio compression format that surpasses mp3 in quality and rivals new formats such as AAC and TwinVQ (a.k.a. VQF).

PAL - Short for Phase Alternating Line, the dominant television standard in Europe. The United States uses a different standard, NTSC. PAL delivers 625 lines at 50 fields (half-frames interlaced) per second. The resolution of a PAL VCD is 352x288 pixels, a PAL SVCD is 480x576, and a PAL full D1 DVD is 704 or 720 x 576.

Pan & Scan - Pan & Scan is one method of adjusting widescreen film images so that they can be shown within the proportions of a standard definition 4:3 aspect ratio television screen, often cropping off the sides of the original widescreen image to focus on the composition's most important aspects.


RM/RMVB - RM stands for Real Media. Real Media is 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 files are often heavily compressed so they can stream over dial-up Internet connections.

TP - TP is a file extension for an ATSC Tansport stream.Transport stream (TS, TP, MPEG-TS, or M2T) is a communications protocal for audio,video, and data which is specified in MPEG-2 Part 1, Systems (ISO/IEC standard 13818-1).Its design goal is to allow multiplexing of digital video and audio and to synchronize the output. Transport stream offers features for error correction for transportation over unreliable media, and is used in broadcast applications such as DVB and ATSC.

TRP - TRP format is a container format that encapsulates packetized elementary streams and other data.

TS - A kind of MPEG Transport stream which is a communications protocol for audio,video, and data which is specified in MPEG-2 Part 1, Systems (ISO/IEC standard 13818-1).Its design goal is to allow multiplexing of digital video and audio and to synchronize the output.TS format is a container format that encapsulates packetized elementary streams and other data.

VOB - All DVD movies are stored in on a DVD video disc in so-called VOB files. VOB files usually contain multiplexed Dolby Digital audio and MPEG-2 video. VOB files on a DVD are numbered as follows: vts_XX_y.vob where XX represents the title and Y the part of the title. There can be 99 titles and 10 parts, although vts_XX_0.vob does not contain any video, usually just menu or navigational information. You can find them on a DVD video disc in a subdirectory labeled VIDEO_TS (all upper case).

WAV - (WAVE), short for Waveform audio format, is a Microsoft and IBM audio file format standard for storing audio on PCs. It is the main format used on Windows systems for raw audio. The most common WAV format contains uncompressed audio and uncompressed WAV files are quite large in size, so, it has declined in popularity. WAV files are probably the simplest of the common formats for storing audio samples. Unlike MPEG audio and other compressed formats, WAVs store samples "in the raw" where no pre-processing is required other that formatting of the data. The WAV file itself consists of three "chunks" of information: The RIFF chunk which identifies the file as a WAV file, The FORMAT chunk which identifies parameters such as sample rate and the DATA chunk which contains the actual data (samples).

WMA - (Windows Media Audio) is an audio data compression technology developed by Microsoft. It can be played by Windows Media player, RealPlayer, Winamp, Windows Movie Maker, and the Microsoft Zune media management software supports most WMA codec. Its audio quality is better than mp3 when the bitstream is below 128kbps, but won't get much improvement when the bitstream gets higher.

WMV - Windows Media file with Audio and/or Video (WMV): You can use a WMV file either to download and play files or to stream content. The WMV file format is similar to the ASF file format.

XviD - is an ISO MPEG-4 compliant video codec. It's not a product but an open source project which is developed and maintained by people around the world.

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