MP3 is a coding format for digital audio developed largely by the Fraunhofer Society in Germany under the lead of Karlheinz Brandenburg. It was designed to greatly reduce the amount of data required to represent audio, yet still sound like a faithful reproduction of the original uncompressed audio to most listeners; for example, compared to CD-quality digital audio, MP3 compression can commonly achieve a 75–95% reduction in size, depending on the bit rate. In popular usage, MP3 often refers to files of sound or music recordings stored in the MP3 file format (.mp3) on consumer electronic devices.
Windows Media Audio (WMA) is a series of audio codecs and their corresponding audio coding formats developed by Microsoft. It is a proprietary technology that forms part of the Windows Media framework. WMA consists of four distinct codecs. The original WMA codec, known simply as WMA, was conceived as a competitor to the popular MP3 and RealAudio codecs. WMA Pro, a newer and more advanced codec, supports multichannel and high-resolution audio. A lossless codec, WMA Lossless, compresses audio data without loss of audio fidelity. WMA Voice, targeted at voice content, applies compression using a range of low bit rates. Microsoft has also developed a digital container format called Advanced Systems Format to store audio encoded by WMA.
Dolby Digital, originally synonymous with Dolby AC-3, is the name for a family of audio compression technologies developed by Dolby Laboratories. Called Dolby Stereo Digital until 1995, it is lossy compression. The first use of Dolby Digital was to provide digital sound in cinemas from 35 mm film prints. It has since also been used for TV broadcast, radio broadcast via satellite, digital video streaming, DVDs, Blu-ray discs and game consoles.
DVD-Audio is a digital format for delivering high-fidelity audio content on a DVD. DVD-Audio uses most of the storage on the disc for high-quality audio and is not intended to be a video delivery format.
Advanced Audio Coding (AAC) is an audio coding standard for lossy digital audio compression. It was designed to be the successor of the MP3 format and generally achieves higher sound quality than MP3 at the same bit rate.
WinDVD is a commercial DVD video player software for Microsoft Windows.
Adobe Audition is a digital audio workstation developed by Adobe Inc. featuring both a multitrack, non-destructive mix/edit environment and a destructive-approach waveform editing view.
The Personal Jukebox was the first consumer hard drive-based digital audio player. Introduced in 1999, it preceded the Apple iPod, SanDisk Sansa, and other similar players. It was designed and developed by Compaq Research starting in May 1998. Compaq did not release the player themselves, but licensed the design to HanGo Electronics Co., Ltd. of South Korea.
High-Efficiency Advanced Audio Coding (HE-AAC) is an audio coding format for lossy data compression of digital audio defined as an MPEG-4 Audio profile in ISO/IEC 14496–3. It is an extension of Low Complexity AAC (AAC-LC) optimized for low-bitrate applications such as streaming audio. The usage profile HE-AAC v1 uses spectral band replication (SBR) to enhance the modified discrete cosine transform (MDCT) compression efficiency in the frequency domain. The usage profile HE-AAC v2 couples SBR with Parametric Stereo (PS) to further enhance the compression efficiency of stereo signals.
DTS, Inc. is an American company. DTS company makes multichannel audio technologies for film and video. Based in Calabasas, California, the company introduced its DTS technology in 1993 as a competitor to Dolby Laboratories, incorporating DTS in the film Jurassic Park (1993). The DTS product is used in surround sound formats for both commercial/theatrical and consumer-grade applications. It was known as The Digital Experience until 1995. DTS licenses its technologies to consumer electronics manufacturers.
Fraunhofer l3enc was the first public software able to encode pulse-code modulation (PCM) .wav files to the MP3 format. The first public version was released on July 13, 1994. This command-line tool was shareware and limited to 112 kbit/s. l3enc fit on a single 3.5" floppy. It was available for MS-DOS, Linux, Solaris, SunOS, NeXTstep and IRIX. A licence that allowed full use cost 350 Deutsche Mark, or about $250 (US).
WinPlay3 was the first real-time MP3 audio player for PCs running Windows, both 16-bit and 32-bit. Prior to this, audio compressed with MP3 had to be decompressed prior to listening. It was released by Fraunhofer IIS, creators of the MP3 format, on September 9, 1995. The latest version was released on May 23, 1997. Since then, the Fraunhofer Society has removed any trace and mention of WinPlay3 from their web sites. However, the software remains available by utilizing the Web Archive.
Ensonido is a real-time post processing algorithm that allows users to play back MP3 Surround files in standard headphones. Ensonido was developed by the Fraunhofer Society. It simulates the natural reception of surround sound by the human ear, which usually receives tones from surrounding loudspeakers and from reflections and echoes of the listening room. The out-of-head localization achieved that way increases the listening comfort noticeably in contrast to conventional stereo headphone listening with its in-head localization of all sounds. In version 3.0 of the Fraunhofer IIS MP3 Surround Player, Ensonido is replaced with newer mp3HD.
mp3 SX is a program that allows users to upgrade mp3 stereo files to MP3 Surround files. mp3 SX analyzes the existing natural ambience of the stereo material and plays it back through the rear channels. The sound sources remain in the front channels, but are played back through the left, center, and right channel, providing a stable front image even for off-sweet-spot listening. The mp3 SX program preserves the original stereo sound stage, creating additional surround envelopment, with only 15 kB/s additional information.
MPEG Multichannel, also known as MPEG-2 Backwards Compatible, or MPEG-2 BC, is an extension to the MPEG-1 Layer II audio compression specification, as defined in the MPEG-2 Audio standard which allows it provide up to 5.1-channels of audio. To maintain backwards compatibility with the older 2-channel (stereo) audio specification, it uses a channel matrixing scheme, where the additional channels are mixed into the two backwards compatible channels. Extra information in the data stream contains signals to process extra channels from the matrix.
MPEG Surround, also known as Spatial Audio Coding (SAC) is a lossy compression format for surround sound that provides a method for extending mono or stereo audio services to multi-channel audio in a backwards compatible fashion. The total bit rates used for the core and the MPEG Surround data are typically only slightly higher than the bit rates used for coding of the core. MPEG Surround adds a side-information stream to the core bit stream, containing spatial image data. Legacy stereo playback systems will ignore this side-information while players supporting MPEG Surround decoding will output the reconstructed multi-channel audio.
In audio engineering, joint encoding refers to a joining of several channels of similar information during encoding in order to obtain higher quality, a smaller file size, or both.
Unified Speech and Audio Coding (USAC) is an audio compression format and codec for both music and speech or any mix of speech and audio using very low bit rates between 12 and 64 kbit/s. It was developed by Moving Picture Experts Group (MPEG) and was published as an international standard ISO/IEC 23003-3 and also as an MPEG-4 Audio Object Type in ISO/IEC 14496-3:2009/Amd 3 in 2012.
Fraunhofer FDK AAC is an open-source library for encoding and decoding digital audio in the Advanced Audio Coding (AAC) format. Fraunhofer IIS developed this library for Android 4.1. It supports several Audio Object Types including MPEG-2 and MPEG-4 AAC LC, HE-AAC, HE-AACv2 as well AAC-LD and AAC-ELD for real-time communication. The encoding library supports sample rates up to 96 kHz and up to eight channels.
MPEG-H 3D Audio, specified as ISO/IEC 23008-3, is an audio coding standard developed by the ISO/IEC Moving Picture Experts Group (MPEG) to support coding audio as audio channels, audio objects, or higher order ambisonics (HOA). MPEG-H 3D Audio can support up to 64 loudspeaker channels and 128 codec core channels.
