16:9 16:9 refers to an Aspect ratio (AR) with a height that's 9/16 the width. It's also commonly referred to as 1.78:1 or simply 1.78, in reference to the width being approximately 1.78 times the height. When a HDTV display is referred to as Widescreen it almost always implies this AR.
4:3 4:3 - (synonyms: Full Frame, Fullscreen, Academy Ratio) - 4:3 refers to an Aspect ratio (AR) with a height that's 3/4 the width. It's also commonly referred to as 1.33:1 or simply 1.33, in reference to the width being approximately 1.33 times the height. This AR is also commonly referred to as fullscreen, referring to the fact that video with this Aspect Ratio fills the full screen of an analog TV. Widescreen video, on the other hand, must be letterboxed, or vertically compressed to be viewed properly on a 4:3 TV, resulting in only part of the screen being used for the image.
3GPP Established in December 1998, the 3rd Generation Partnership Project (3GPP) consists of telecommunications standards bodies collaborating to make a third generation (3G) mobile phone system specification for global use. The organizations are known as the "Organizational Partners" of the project. The project was established after the signing of the "The 3rd Generation Partnership Project Agreement".
1080i 1080i refers to an interlaced HDTV signal with 1080 horizontal lines and an Aspect ratio of 16:9 (1.78:1). All major HDTV broadcasting standards include a 1080i format which has a Resolution of 1920x1080, however there are other formats, including HDV and AVCHD for camcorders, which utilize 1080i images with a resolution of 1440x1080. Confusing matters even further, a 4:3 (1.33:1) image broadcast in 1080i (1920x1080) uses the center 1440 Pixels for the image, with 240 pixel wide pillarbox borders on each side.
1080p 1080p refers to a progressive HDTV signal with 1080 horizontal lines and an Aspect Ratio of 16:9 (1.78:1). All major HDTV broadcasting standards include a 1080i format which has a resolution of 1920x1080, but the progressive HDTV broadcast standards in place right now only allow a resolution of 1280x720 (720p). Currently the only applications using 1080p signals are Blu-ray and HD DVD.
AAC - (synonyms: AacPlus v2, HE-AAC,AAC LC) Advanced Audio Coding, or AAC, is a MPEG (Motion Pictures Experts Group) audio standard first adopted as part of the MPEG-2 family of standards. Like its predecessor, MP3, AAC is a Lossy Compression format capable of delivering relatively high quality at relatively low bitrates. There are actually two AAC specifications. In addition to the MPEG-2 version of AAC, which was also referred to early on as NBC for Non Backwards Compatible, there's a newer specification developed for MPEG-4. This version is normally found in the MP4 Container, either with or without accompanying video.
Alpha There are a few stages in product development and alpha is one of these development stages. A product in alpha stage will satisfy all software requirements but will not have been completely tested or it could possibly be missing minor features. Products in alpha are considered to be in the first major stage of the so-called "release cycle" and that is where the name "alpha" comes from. Alpha is the first letter of the Greek alphabet. Products in alpha are generally considered to be only 35-40% complete and will be very buggy.
ASF - Advanced Streaming Format Microsoft's new audio/video format, meant specifically for streaming purposes. It doesn't specify how the video or audio should be encoded, but instead just specifies the structure of the video/audio stream. This means that ASF files can be encoded with basically any audio/video codec and would still be in ASF format. Many times ASF is confused with Microsoft's implementation of MPEG-4 video format, because most of the ASF streams are encoded using this technology.
AVI AVI, which stands for Audio Video Interleave, is a Container format used by Microsoft's Video for Windows multimedia framework. Since it was developed for Windows 3.1 in 1992 it lacks some features found in newer containers like MPEG or MP4, but is still widely used by consumers and even supported by some standalone DVD players. Although still supported in Windows, and suitable for certain formats like DV, it's not a good general purpose container, and even Microsoft uses other containers for their own video formats.
ATRAC3 ATRAC stands for Adaptive Transform Acoustic Coding and ATRAC3 is an evolution of the earlier ATRAC1 system used with Sony's SDDS theater audio system and the MiniDisc format. ATRAC3 offers two separate modes, LP2 mode and LP4 mode. LP2 uses a uses a 132 kbit/s data rate, which is claimed to offer the same quality as MP3 audio at the same or similar bitrate, or so says Sony-funded tests of both audio formats.
ATRAC3plus ATRAC stands for Adaptive Transform Acoustic Coding and ATRAC3 is an evolution of the earlier ATRAC1 system used with Sony's SDDS theater audio system and the MiniDisc format. ATRAC3plus is an extension of the ATRAC3 format. The codec is used with Sony HiMD Walkman device, PlayStation 3 (PS3), PlayStation Portable (PSP), VAIO pocket and ATRAC CD players. It used four times the transform window of ATRAC3, stretching to 4096 samples with a signal split into 16 sub-bands pre bit allocation and MDCT processes.
AVC / H.264 MPEG-4 Part 10, also known as MPEG-4 AVC (Advanced Video Coding), is actually defined in an identical pair of standards maintained by different organizations, together known as the Joint Video Team (JVT). While MPEG-4 Part 10 is a ISO/IEC standard, it was developed in cooperation with the ITU, an organization heavily involved in broadcast television standards. Since the ITU designation for the standard is H.264, you may see MPEG-4 Part 10 video referred to as either AVC or H.264. Both are valid, and refer to the same standard.
AVS AVS stands for Audio Video Standard. It's development was initiated by the People's Republic of China and its patents are 90% owned by Chinese companies. It is competing with H.264 / AAC to replace MPEG-2 video. AVS is a compression codec for both audio and video formats, and files containing AVS content carry the .avs extension (not to be confused with AviSynth scripts which carry the same extension).