- AAC — Advanced Audio Coding, and in the beginning it was also called MPEG-2 NBC for "Non-Backwards Compatible" as opposed to the MPEG-1 and MPEG-2 BC (with 5.1 channels) standards. It is considered to be the actual "state of the art" in general audio coding and the natural successor of MPEG-1/2 Layer III / MP3 in the multimedia standard MPEG-4 that uses MP4 as the container format for all kinds of content.
- AC3 — Initially known as Audio Coding 3 AC3 is a synonym for Dolby Digital these days. Dolby Digital is an advanced audio compression technology allowing to encode up to 6 separate channels at bitrates up to 448kbit/s.
- AMD — Advanced Micro Devices, Inc. (abbreviated AMD; NYSE: AMD) is a manufacturer of integrated circuits based in Sunnyvale, California. It is the second-largest supplier of x86-compatible processors, and a leading supplier of non-volatile flash memory. It was founded in 1969 by a group of defectors from Fairchild Semiconductor, including Jerry Sanders. AMD's current CEO is Dr. Hector Ruiz. The current president and Chief Operating Officer is Dirk Meyer.
- API — application programming interface.
- ARM — The ARM architecture (originally the Acorn RISC Machine) is a 32-bit RISC processor architecture that is widely used in a number embedded designs. Due to their power saving features, ARM CPUs are dominant in the mobile electronics market, where low-power consumption is a critical design goal.
- ASF — Advanced Streaming Format. Microsoft's answer to Real Media and streaming media in general.
- ATSC. DVS157 — Advanced Television Systems Committee. In 1978, the Federal Communications Commission (FCC) empaneled the Advisory Committee on Advanced Television Service (ACATS) as an investigatory and advisory committee to develop information that would assist the FCC in establishing an advanced broadcast television (ATV) standard for the United States. This committee created a subcommittee, the ATSC, to explore the need for and to coordinate development of the documentation of Advanced Television Systems. In 1993, the ATSC recommended that efforts be limited to a digital television system (DTV), and in September 1995 issued its recommendation for a Digital Television System standard, which was approved with the exclusion of compression format constraints (picture resolution, frame rate, and frame sequence).
- AVC/H.264 — is the latest ratified video coding standard. It emerged as the result of joint development of International Telecommunication Union Video Coding Experts Group (ITU VCEG) and MPEG ISO. This standard is known as H.264 (ITU-T name), or MPEG-4 part 10 (ISO/IEC 14496-10), or MPEG-4 Advanced Video Coding (AVC).
- AVI — Audio/Video Interleaved - Standard that has been designed by Microsoft. AVI is the file format in which the audio and video data are alternated one after another. During playback a sound-track is synchronized with video.