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SBC (codec)
SBC, or low-complexity subband codec, is an audio subband codec specified by the Bluetooth Special Interest Group (SIG) for the Advanced Audio Distribution Profile (A2DP).Bluetooth SIG, Specification of the Bluetooth System, Profiles, Advanced Audio Distribution Profile version 1.3. https://www.bluetooth.org/docman/handlers/DownloadDoc.ashx?doc_id=260859&vId=290074 SBC is a digital audio encoder and decoder used to transfer data to Bluetooth audio output devices like headphones or loudspeakers. It can also be used on the Internet. It was designed with Bluetooth bandwidth limitations and processing power in mind to obtain a reasonably good audio quality at medium bit rates with low computational complexity. As of A2DP version 1.3, the Low Complexity Subband Coding remains the default codec and its implementation is mandatory for devices supporting that profile, but vendors are free to add their own codecs to match their needs. At CES 2020 the Bluetooth SIG announced LC3 as the s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Subband Coding
In signal processing, sub-band coding (SBC) is any form of transform coding that breaks a signal into a number of different frequency bands, typically by using a fast Fourier transform, and encodes each one independently. This decomposition is often the first step in data compression for audio and video signals. SBC is the core technique used in many popular lossy audio compression algorithms including MP3. Encoding audio signals The simplest way to digitally encode audio signals is pulse-code modulation (PCM), which is used on audio CDs, Digital Audio Tape, DAT recordings, and so on. Digitization transforms continuous signals into discrete ones by sampling a signal's amplitude at uniform intervals and rounding to the nearest value representable with the available Audio bit depth, number of bits. This process is fundamentally inexact, and involves two errors: ''discretization error,'' from sampling at intervals, and ''quantization error,'' from rounding. The more bits used t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Sampling Rate
In signal processing, sampling is the reduction of a continuous-time signal to a discrete-time signal. A common example is the conversion of a sound wave to a sequence of "samples". A sample is a value of the signal at a point in time and/or space; this definition differs from the term's usage in statistics, which refers to a set of such values. A sampler is a subsystem or operation that extracts samples from a continuous signal. A theoretical ideal sampler produces samples equivalent to the instantaneous value of the continuous signal at the desired points. The original signal can be reconstructed from a sequence of samples, up to the Nyquist limit, by passing the sequence of samples through a reconstruction filter. Theory Functions of space, time, or any other dimension can be sampled, and similarly in two or more dimensions. For functions that vary with time, let s(t) be a continuous function (or "signal") to be sampled, and let sampling be performed by measuring t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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List Of Codecs
The following is a list of compression formats and related codecs. Audio compression formats Non-compression * Linear pulse-code modulation (LPCM, generally only described as PCM) is the format for uncompressed audio in media files and it is also the standard for CD-DA; note that in computers, LPCM is usually stored in container formats such as WAV, AIFF, or AU, or as raw audio format, although not technically necessary. ** FFmpeg * Pulse-density modulation (PDM) ** Direct Stream Digital (DSD) is standard for Super Audio CD *** foobar2000 Super Audio CD Decoder (based on MPEG-4 DST reference decoder) *** FFmpeg (based on dsd2pcm) * Pulse-amplitude modulation (PAM) Lossless compression * Actively used ** Most popular *** Free Lossless Audio Codec (FLAC) **** libFLAC **** FFmpeg *** Apple Lossless Audio Codec (ALAC) **** Apple QuickTime **** libalac **** FFmpeg **** Apple Music *** Monkey's Audio (APE) **** Monkey's Audio SDK **** FFmpeg (decoder only) *** OptimFRO ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Adaptive Differential Pulse-code Modulation
Adaptive differential pulse-code modulation (ADPCM) is a variant of differential pulse-code modulation (DPCM) that varies the size of the quantization step, to allow further reduction of the required data bandwidth for a given signal-to-noise ratio. Typically, the adaptation to signal statistics in ADPCM consists simply of an adaptive scale factor before quantizing the difference in the DPCM encoder. ADPCM was developed for speech coding by P. Cummiskey, Nikil S. Jayant and James L. Flanagan at Bell Labs in 1973. In telephony In telephony, a standard audio signal for a single phone call is encoded as 8000 analog samples per second, of 8 bits each, giving a 64 kbit/s digital signal known as DS0. The default signal compression encoding on a DS0 is either μ-law (mu-law) PCM (North America and Japan) or A-law PCM (Europe and most of the rest of the world). These are logarithmic compression systems where a 13- or 14-bit linear PCM sample number is mapped into an 8-bit value ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Audio Codec
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 a 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 contai ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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BlueZ
A Bluetooth stack is software that is an implementation of the Bluetooth protocol stack. Bluetooth stacks can be roughly divided into two distinct categories: # ''General-purpose'' implementations that are written with emphasis on feature-richness and flexibility, usually for desktop computers. Support for additional Bluetooth profiles can typically be added through drivers. # ''Embedded system'' implementations intended for use in devices where resources are limited and demands are lower, such as Bluetooth peripheral devices. General-purpose implementations BSD FreeBSD The FreeBSD bluetooth stack is implemented using the Netgraph framework. A broad variety of Bluetooth USB dongles are supported by the ng_ubt driver. The implementation was committed in 2002, and first released with FreeBSD 5.0. * NetBSD NetBSD has its own Bluetooth implementation, committed in 2006, and first released with . OpenBSD OpenBSD has had the implementation from NetBSD for some time, but it was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Reference Implementation
In the software development process, a reference implementation (or, less frequently, sample implementation or model implementation) is a program that implements all requirements from a corresponding specification. The reference implementation often accompanies a technical standard, and demonstrates what should be considered the "correct" behavior of any other implementation of it. Characteristics and examples Reference implementations of algorithms, for instance cryptographic algorithms, are often the result or the input of standardization processes. In this function they are often dedicated to the public domain with their source code as public domain software. Examples are the first CERN's httpd, Serpent cipher, base64 variants, and SHA-3. The Openwall Project maintains a list of several algorithms with their reference source code In computing, source code, or simply code or source, is a plain text computer program written in a programming language. A programmer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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CSR (company)
CSR plc (formerly Cambridge Silicon Radio) was a multinational fabless semiconductor company headquartered in Cambridge, United Kingdom. Its main products were connectivity, audio, imaging and location chips. CSR was listed on the London Stock Exchange and was a constituent of the FTSE 250 Index until it was acquired by Qualcomm in August 2015. Under Qualcomm's ownership, the company was renamed Qualcomm Technologies International, Ltd. History The company was founded in 1998 and split away from Cambridge Consultants as ''Cambridge Silicon Radio'' or CSR in 1999. The founding directors, who were all at Cambridge Consultants at the time were Phil O'Donovan, James Collier and Glenn Collinson. It was first listed on the London Stock Exchange in 2004. In 2005 the company acquired Clarity Technologies, a leading clear voice capture (CVC) business and UbiNetics, a 3G wireless (WCDMA/UMTS/HSDPA) technology company. In 2007, CSR acquired Nordnav, a Swedish-based GPS software co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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AptX
aptX (''apt'' stands for ''audio processing technology'') is a family of proprietary audio codec compression algorithms owned by Qualcomm, with a heavy emphasis on wireless audio applications. History The original compression algorithm was developed in the 1980s by Dr. Stephen Smyth as part of his Ph.D. research at Queen's University Belfast School of Electronics, Electrical Engineering and Computer Science. Its design is based on time domain ADPCM principles without psychoacoustic auditory masking techniques. The algorithm was then commercialized under the name aptX and first introduced to the commercial market as a semiconductor product, a custom programmed DSP integrated circuit with part name APTX100ED, which was initially adopted by broadcast automation equipment manufacturers who required a means to store CD-quality audio on a computer hard disk drive for automatic playout during a radio show, for example, hence replacing the task of the disc jockey. The company w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Lineage OS
LineageOS is an open source Android operating system for smartphones, tablets, and set-top boxes. It is community-developed and serves as the successor to CyanogenMod, from which it was forked in December 2016. As of 2023, there are about 1.5 million devices running LineageOS. History In 2009, CyanogenMod was created by Stefanie Jane (Cyanogen). In 2013, Jane obtained venture funding under the name Cyanogen Inc. to allow commercialization of the project. In 2016, as part of a corporate restructure which involved a change of CEO, closure of offices and projects, and cessation of services, Jane either left or was forced out of Cyanogen Inc. The LineageOS project was formed as a fork of it and was officially launched on 24 December 2016. Since Cyanogen Inc. retained the rights to the Cyanogen name, the project rebranded its fork as LineageOS. LineageOS beginning The code itself, being open source, was forked around December 2016 under the new name LineageOS and efforts ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Bit Rate
In telecommunications and computing, bit rate (bitrate or as a variable ''R'') is the number of bits that are conveyed or processed per unit of time. The bit rate is expressed in the unit bit per second (symbol: bit/s), often in conjunction with an SI prefix such as kilo (1 kbit/s = 1,000 bit/s), mega (1 Mbit/s = 1,000 kbit/s), giga (1 Gbit/s = 1,000 Mbit/s) or tera (1 Tbit/s = 1,000 Gbit/s). The non-standard abbreviation bps is often used to replace the standard symbol bit/s, so that, for example, 1 Mbps is used to mean one million bits per second. In most computing and digital communication environments, one byte per second (symbol: B/s) corresponds roughly to 8 bit/s. However if stop bits, start bits, and parity bits need to be factored in, a higher number of bits per second will be required to achieve a throughput of the same number of bytes. Prefixes When quantifying large or small bit rates, SI ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Qualcomm
Qualcomm Incorporated () is an American multinational corporation headquartered in San Diego, California, and Delaware General Corporation Law, incorporated in Delaware. It creates semiconductors, software and services related to wireless technology. It owns patents critical to the 5G, 4G, CDMA2000, TD-SCDMA and WCDMA mobile communications standards. Qualcomm was established in 1985 by Irwin M. Jacobs, Irwin Jacobs and six other co-founders. Its early research into CDMA wireless cell phone technology was funded by selling a two-way mobile digital satellite communications system known as Omnitracs. After a heated debate in the wireless industry, CDMA was adopted as a 2G standard in North America, with Qualcomm's patents incorporated. Afterwards, there was a series of legal disputes about pricing for licensing patents required by the standard. Over the years, Qualcomm has expanded into selling semiconductor products in a predominantly fabless manufacturing model. It also develope ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |