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Comparison Of Audio Coding Formats
The following tables compare general and technical information for a variety of audio coding formats. For listening tests comparing the perceived audio quality of audio formats and codecs, see the article Codec listening test. General information Notes # The 'Music' category is merely a guideline on commercialized uses of a particular format, not a technical assessment of its capabilities. For example, MP3 and AAC dominate the personal audio market in terms of market share, though many other formats are comparably well suited to fill this role from a purely technical standpoint. # First public release date is first of either specification publishing or source releasing, or in the case of closed-specification, closed-source codecs, is the date of first binary releasing. Many developing codecs have pre-releases consisting of pre-1.0 versions and perhaps 1.0 release candidates (RCs), although 1.0 may not necessarily be the release version. # Latest stable version is that of sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Audio Coding Format
An audio coding format (or sometimes audio compression format) is a content representation format for storage or transmission of digital audio (such as in digital television, digital radio and in audio and video files). Examples of audio coding formats include MP3, AAC, Vorbis, FLAC, and Opus. A specific software or hardware implementation capable of audio compression and decompression to/from a specific audio coding format is called an '' audio codec''; an example of an audio codec is LAME, which is one of several different codecs which implements encoding and decoding audio in the MP3 audio coding format in software. Some audio coding formats are documented by a detailed technical specification document known as an audio coding specification. Some such specifications are written and approved by standardization organizations as technical standards, and are thus known as an audio coding standard. The term "standard" is also sometimes used for ''de facto'' standards as wel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ITunes
iTunes is a media player, media library, and mobile device management (MDM) utility developed by Apple. It is used to purchase, play, download and organize digital multimedia on personal computers running the macOS and Windows operating systems, and can be used to rip songs from CDs as well as playing content from dynamic, smart playlists. It includes options for sound optimization and wirelessly sharing iTunes libraries. iTunes was announced by Apple CEO Steve Jobs on January 9, 2001. Its original and main focus was music, with a library offering organization and storage of Mac users' music collections. With the 2003 addition of the iTunes Store for purchasing and downloading digital music, and a Windows version of the program, it became an ubiquitous tool for managing music and configuring other features on Apple's line of iPod media players, which extended to the iPhone and iPad upon their introduction. From 2005 on, Apple expanded its core music features with s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Camcorder
A camcorder is a self-contained portable electronic device with video and recording as its primary function. It is typically equipped with an articulating screen mounted on the left side, a belt to facilitate holding on the right side, hot-swappable battery facing towards the user, hot-swappable recording media, and an internally contained quiet optical zoom lens. The earliest camcorders were tape-based, recording analog signals onto videotape cassettes. In the 2000s, digital recording became the norm, and additionally tape was replaced by storage media such as mini- HDD, MiniDVD, internal flash memory and SD cards. More recent devices capable of recording video are camera phones and digital cameras primarily intended for still pictures, whereas dedicated camcorders are often equipped with more functions and interfaces than more common cameras, such as an internal optical zoom lens that is able to operate silently with no throttled speed, whereas cameras with protract ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digital Television
Digital television (DTV) is the transmission of television signals using Digital signal, digital encoding, in contrast to the earlier analog television technology which used analog signals. At the time of its development it was considered an innovative advancement and represented the first significant evolution in television technology since color television in the 1950s. Modern digital television is transmitted in high-definition television (HDTV) with greater resolution than analog TV. It typically uses a widescreen aspect ratio (commonly 16:9) in contrast to the narrower format (4:3) of analog TV. It makes more economical use of scarce radio spectrum space; it can transmit up to seven channels in the same Bandwidth (signal processing), bandwidth as a single analog channel, and provides many new features that analog television cannot. A digital television transition, transition from analog to digital broadcasting began around 2000. Different digital television broadcasting st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DVD Players
A DVD player is a machine that plays DVDs produced under both the DVD-Video and DVD-Audio technical standards, two different and incompatible standards. Some DVD players will also play audio CDs. DVD players are connected to a television to watch the DVD content, which could be a movie, a recorded TV show, or other content. History The first DVD player is claimed to have been created by the Japanese electronics vendor Toshiba in November 1996, and the first to be released to US customers is claimed to have been by Sony in April 1997. Some manufacturers originally announced that DVD players would be available as early as the middle of 1996. These predictions were too optimistic. Delivery was initially held up for "political" reasons of copy protection demanded by movie studios, but was later delayed by lack of movie titles. The first players appeared in Japan on November 1, 1996, followed by the United States on March 31, 1997, with distribution limited to only seven major ci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dolby Laboratories
Dolby Laboratories, Inc. (Dolby Labs or simply Dolby) is a British-American technology corporation specializing in audio noise reduction, audio data compression, audio encoding/compression, spatial audio, and high-dynamic-range television (HDR) imaging. Dolby licenses its technologies to consumer electronics manufacturers. History Dolby Labs was founded by Ray Dolby (1933–2013) in London, England, in 1965. In the same year, he invented the Dolby noise-reduction system, Dolby Noise Reduction system, a form of audio signal processing for reducing the background hissing sound on cassette tape recordings. His first U.S. patent on the technology was filed in 1969, four years later. The method was first used by Decca Records in the UK. After this, other companies began purchasing Dolby’s A301 technology, which was the professional noise reduction system used in recording, motion picture, broadcasting stations and communications networks. These companies include BBC, Pye Records ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dolby Digital
Dolby Digital, originally synonymous with Dolby AC-3 (see below), is the name for a family of audio compression technologies developed by Dolby Laboratories. Called Dolby Stereo Digital until 1995, it is lossy compression (except for Dolby TrueHD). 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. Dolby AC-3 was the original version of the Dolby Digital codec. The basis of the Dolby AC-3 multi-channel audio coding standard is the modified discrete cosine transform (MDCT), a lossy audio compression algorithm. It is a modification of the discrete cosine transform (DCT) algorithm, which was proposed by Nasir Ahmed in 1972 for image compression. The DCT was adapted into the MDCT by J.P. Princen, A.W. Johnson and Alan B. Bradley at the University of Surrey in 1987. Dolby Laboratories adap ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
FairPlay
FairPlay is a family of digital rights management (DRM) technologies developed by Apple Inc. for protecting videos, books and apps and historically for music. Music The initial version of FairPlay was created to protect music on the iTunes Store, and is the only version of FairPlay that is no longer actively used. Technical details FairPlay is built into the MP4 multimedia file format as an encrypted AAC audio layer. FairPlay-protected files are regular MP4 container files with an encrypted AAC audio layer. The layer is encrypted using the AES algorithm. The master key required to decrypt the audio layer is also stored in encrypted form in the MP4 container file. The key required to decrypt the master key is called the "user key". When a user registers a new computer with iTunes, the device requests authorization from Apple's servers, thereby gaining a user key. Upon attempting to play a file, the master key stored within the file is then matched to the user key, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MPEG-4 SLS
MPEG-4 SLS, or MPEG-4 Scalable to Lossless as per International Organization for Standardization, ISO/International Electrotechnical Commission, IEC 14496-3:2005/Amd 3:2006 (Scalable Lossless Coding), is an extension to the MPEG-4 Part 3 (MPEG-4 Audio) standard to allow Lossless data compression, lossless Audio data compression, audio compression scalable to lossy MPEG-4 General Audio coding methods (e.g., variations of Advanced Audio Coding, AAC). It was developed jointly by the Institute for Infocomm Research (I2R) and Fraunhofer Society, Fraunhofer, which commercializes its implementation of a limited subset of the standard under the name of HD-AAC. Standardization of the HD-AAC profile for MPEG-4 Audio is under development (as of September 2009). MPEG-4 SLS allows having both a lossy layer and a lossless correction layer similar to Wavpack Hybrid, OptimFROG DualStream and DTS-HD Master Audio, providing backwards compatibility to MPEG Advanced Audio Coding, AAC-compliant bitstr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
AAC-LD
The MPEG-4 Low Delay Audio Coder (a.k.a. AAC Low Delay, or AAC-LD) is audio compression standard designed to combine the advantages of perceptual audio coding with the low delay necessary for two-way communication. It is closely derived from the MPEG-2 Advanced Audio Coding (AAC) standard. It was published in MPEG-4 Audio Version 2 (ISO/ IEC 14496-3:1999/Amd 1:2000) and in its later revisions. AAC-LD uses a version of the modified discrete cosine transform (MDCT) audio coding technique called the LD-MDCT. AAC-LD is widely used by Apple as the voice-over-IP (VoIP) speech codec in FaceTime. Real time CODEC requirements The most stringent requirements are a maximum algorithmic delay of only 20 ms and a good audio quality for all kind of audio signals including speech and music. * The AAC-LD coding scheme bridges the gap between speech coding schemes and high quality audio coding schemes. Two-way communication with AAC-LD is possible on usual analog telephone lines and via I ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fraunhofer FDK AAC
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 (AAC LC + SBR), HE-AACv2 (LC + SBR + PS) as well AAC-LD (low delay) and AAC-ELD (enhanced low delay) for real-time communication. The encoding library supports sample rates up to 96 kHz and up to eight channels (7.1 surround). Operation The Android-targeted implementation of the Fraunhofer AAC encoder uses fixed-point math and is optimized for encoding on embedded devices/mobile phones. The library is currently limited to 16-bit PCM input. Other versions of the Fraunhofer encoder, like the one included in Winamp, are optimized for encoding music on desktop-class processors. Those versions of the encoder, however, are not open-source and require a commercial license. Version 2 of the library, introduced wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
