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Unified Speech And Audio Coding
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 (a.k.a. MPEG-D Part 3) and also as an MPEG-4 Audio Object Type in ISO/IEC 14496-3:2009/Amd 3 in 2012. It uses time-domain linear prediction and residual coding tools (ACELP-like techniques) for speech signal segments and transform coding tools (MDCT-based techniques) for music signal segments and it is able to switch between the tool sets dynamically in a signal-responsive manner. It is being developed with the aim of a single, unified coder with performance that equals or surpasses that of dedicated speech coders and dedicated music coders over a broad range of bitrates. Enhanced variations of the MPEG-4 Spectral Band Replication (SBR) and MPEG-D MPEG Surround parametric c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Data Compression
In information theory, data compression, source coding, or bit-rate reduction is the process of encoding information using fewer bits than the original representation. Any particular compression is either lossy or lossless. Lossless compression reduces bits by identifying and eliminating statistical redundancy. No information is lost in lossless compression. Lossy compression reduces bits by removing unnecessary or less important information. Typically, a device that performs data compression is referred to as an encoder, and one that performs the reversal of the process (decompression) as a decoder. The process of reducing the size of a data file is often referred to as data compression. In the context of data transmission, it is called source coding; encoding done at the source of the data before it is stored or transmitted. Source coding should not be confused with channel coding, for error detection and correction or line coding, the means for mapping data onto a signal. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
High-Efficiency Advanced Audio Coding
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. HE-AAC is used in digital radio standards like HD Radio, DAB+ and Digital Radio Mondiale. History The progenitor of HE-AAC was developed by Coding Technologies by combining MPEG-2 AAC-LC with a proprietary mechanism for spectral band replication (SBR), to be used by XM Radio for their satellite radio service. Subsequently, Coding Technologies submitted their SBR mechanism to MPEG as a basis of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Audio Codecs
An audio codec is a device or computer program capable of encoding or decoding a digital data stream (a codec) that encodes or decodes audio. In software, an audio codec is a computer program implementing an algorithm that compresses and decompresses digital audio data according to a given audio file or streaming media audio coding format. The objective of the algorithm is to represent the high-fidelity audio signal with minimum number of bits while retaining quality. This can effectively reduce the storage space and the bandwidth required for transmission of the stored audio file. Most software codecs are implemented as libraries which interface to one or more multimedia players. Most modern audio compression algorithms are based on modified discrete cosine transform (MDCT) coding and linear predictive coding (LPC). In hardware, audio codec refers to a single device that encodes analog audio as digital signals and decodes digital back into analog. In other words, it contains bot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Opus (codec)
Opus is a lossy audio coding format developed by the Xiph.Org Foundation and standardized by the Internet Engineering Task Force, designed to efficiently code speech and general audio in a single format, while remaining low-latency enough for real-time interactive communication and low-complexity enough for low-end embedded processors. Opus replaces both Vorbis and Speex for new applications, and several blind listening tests have ranked it higher-quality than any other standard audio format at any given bitrate until transparency is reached, including MP3, AAC, and HE-AAC. Opus combines the speech-oriented LPC-based SILK algorithm and the lower-latency MDCT-based CELT algorithm, switching between or combining them as needed for maximal efficiency. Bitrate, audio bandwidth, complexity, and algorithm can all be adjusted seamlessly in each frame. Opus has the low algorithmic delay (26.5 ms by default) necessary for use as part of a real-time communication link, network ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Foobar2000
foobar2000 (often abbreviated as fb2k or f2k) is a freeware audio player for Microsoft Windows, iOS and Android developed by Peter Pawłowski. It has a modular design, which provides user flexibility in configuration and customization. Standard "skin" elements can be individually augmented or replaced with different dials and buttons, as well as visualizers such as waveform, oscilloscope, spectrum, spectrogram (waterfall), peak and smoothed VU meters. foobar2000 offers third-party user interface modifications through a software development kit (SDK). foobar2000 supports many audio file formats, has many features for organizing metadata, files, and folders, and has a converter interface for use with command line encoders. To maximize audio fidelity in cases where resampling or downscaling in bit depth is required, it provides noise shaping and dithering. There are a number of official and third-party components which add many additional features. The core is closed source, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microsoft
Microsoft Corporation is an American multinational technology corporation producing computer software, consumer electronics, personal computers, and related services headquartered at the Microsoft Redmond campus located in Redmond, Washington, United States. Its best-known software products are the Windows line of operating systems, the Microsoft Office suite, and the Internet Explorer and Edge web browsers. Its flagship hardware products are the Xbox video game consoles and the Microsoft Surface lineup of touchscreen personal computers. Microsoft ranked No. 21 in the 2020 Fortune 500 rankings of the largest United States corporations by total revenue; it was the world's largest software maker by revenue as of 2019. It is one of the Big Five American information technology companies, alongside Alphabet, Amazon, Apple, and Meta. Microsoft was founded by Bill Gates and Paul Allen on April 4, 1975, to develop and sell BASIC interpreters for the Altair 8800. It rose to do ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
WatchOS
watchOS is the operating system of the Apple Watch, developed by Apple Inc. It is based on iOS, the operating system used by the iPhone, and has many similar features. It was released on April 24, 2015, along with the Apple Watch, the only device that runs watchOS. watchOS exposes an API called ''WatchKit'' for developer use. The second version, watchOS 2, included support for native third-party apps and other improvements, and was released on September 21, 2015. The third version, watchOS 3, was released on September 13, 2016, to emphasize better performance and include new watch faces and stock apps. The fourth version, watchOS 4, was released on September 19, 2017. The fifth version, watchOS 5, was released on September 17, 2018, to add more third-party support and new workouts, along with the "Walkie-Talkie" feature. The sixth version, watchOS 6, was released on September 19, 2019. The seventh version, watchOS 7, was released on September 16, 2020, to support handwashing an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IOS 13
iOS 13 is the thirteenth major release of the iOS mobile operating system developed by Apple Inc. for their iPhone, iPod Touch, and HomePod lines. The successor to iOS 12 on those devices, it was announced at the company's Worldwide Developers Conference (WWDC) on June 3, 2019, and released on September 19, 2019. It was succeeded by iOS 14, released on September 16, 2020. As of iOS 13, the iPad lines run a separate operating system, derived from iOS, named iPadOS. Both iPadOS 13 and iOS 13 dropped support for devices with less than 2 GB of RAM. History Introduction and initial release iOS 13 and iPadOS 13 were introduced by Senior Vice President of Software Engineering Craig Federighi at the WWDC keynote address on June 3, 2019. The first beta was made available to registered developers after the keynote. The second beta was released to registered developers on June 18, 2019, and the first public beta was released on June 24, 2019. The initial release of iOS 13 was v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Android Pie
Android Pie ( codenamed Android P during development), also known as Android 9 (API 28) is the ninth major release and the 16th version of the Android mobile operating system. It was first released as a developer preview on March 7, 2018, and was released publicly on August 6, 2018. On August 6, 2018, Google officially announced the final release of Android 9 under the title "Pie", with the update initially available for current Google Pixel devices, and releases for Android One devices and others to follow "later this year". The Essential Phone was the first third-party Android device to receive an update to Pie, notably coming day-and-date with its final release. The Sony Xperia XZ3 was the first device with Android Pie pre-installed. As of December 2022, 9.17% of all Android devices ran Android 9 Pie (not receiving security updates), with 17.2% of tablets alone still running Pie, making it the 3rd most popular version to date. History Android Pie, then referred to as "And ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digital Radio Mondiale
Digital Radio Mondiale (DRM; ''mondiale'' being Italian and French for "worldwide") is a set of digital audio broadcasting technologies designed to work over the bands currently used for analogue radio broadcasting including AM broadcasting—particularly shortwave—and FM broadcasting. DRM is more spectrally efficient than AM and FM, allowing more stations, at higher quality, into a given amount of bandwidth, using xHE-AAC audio coding format. Various other MPEG-4 and Opus codecs are also compatible, but the standard now specifies xHE-AAC. Digital Radio Mondiale is also the name of the international non-profit consortium that has designed the platform and is now promoting its introduction. Radio France Internationale, TéléDiffusion de France, BBC World Service, Deutsche Welle, Voice of America, Telefunken (now Transradio) and Thomcast (now Ampegon) took part at the formation of the DRM consortium. The principle of DRM is that bandwidth is the limiting factor, and comp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HTTP Live Streaming
HTTP Live Streaming (also known as HLS) is an HTTP-based adaptive bitrate streaming communications protocol developed by Apple Inc. and released in 2009. Support for the protocol is widespread in media players, web browsers, mobile devices, and streaming media servers. As of 2019, an annual video industry survey has consistently found it to be the most popular streaming format. HLS resembles MPEG-DASH in that it works by breaking the overall stream into a sequence of small HTTP-based file downloads, each downloading one short chunk of an overall potentially unbounded transport stream. A list of available streams, encoded at different bit rates, is sent to the client using an extended M3U playlist. Based on standard HTTP transactions, HTTP Live Streaming can traverse any firewall or proxy server that lets through standard HTTP traffic, unlike UDP-based protocols such as RTP. This also allows content to be offered from conventional HTTP servers and delivered over widely available ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MPEG-DASH
Dynamic Adaptive Streaming over HTTP (DASH), also known as MPEG-DASH, is an adaptive bitrate streaming technique that enables high quality streaming of media content over the Internet delivered from conventional HTTP web servers. Similar to Apple's HTTP Live Streaming (HLS) solution, MPEG-DASH works by breaking the content into a sequence of small segments, which are served over HTTP. An early HTTP web server based streaming system called SProxy was developed and deployed in the Hewlett Packard Laboratories in 2006. It showed how to use HTTP range requests to break the content into small segments. SProxy shows the effectiveness of segment based streaming, gaining best Internet penetration due to the wide deployment of firewalls, and reducing the unnecessary traffic transmission if a user chooses to terminate the streaming session earlier before reaching the end. Each segment contains a short interval of playback time of content that is potentially many hours in duration, such as a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
