Hierarchical Modulation
Hierarchical modulation, also called layered modulation, is one of the signal processing techniques for multiplexing and modulating multiple data streams into one single symbol stream, where base-layer symbols and enhancement-layer symbols are synchronously overlaid before transmission. Hierarchical modulation is particularly used to mitigate the cliff effect in digital television broadcast, particularly mobile TV, by providing a (lower quality) fallback signal in case of weak signals, allowing graceful degradation instead of complete signal loss. It has been widely proven and included in various standards, such as DVB-T, MediaFLO, UMB (Ultra Mobile Broadband, a new 3.5th generation mobile network standard developed by 3GPP2), and is under study for DVB-H. Hierarchical modulation is also taken as one of the practical implementations of superposition precoding, which can help achieve the maximum sum rate of broadcast channels. When hierarchical-modulated signals are tran ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Signal Processing
Signal processing is an electrical engineering subfield that focuses on analyzing, modifying and synthesizing ''signals'', such as audio signal processing, sound, image processing, images, Scalar potential, potential fields, Seismic tomography, seismic signals, Altimeter, altimetry processing, and scientific measurements. Signal processing techniques are used to optimize transmissions, Data storage, digital storage efficiency, correcting distorted signals, improve subjective video quality, and to detect or pinpoint components of interest in a measured signal. History According to Alan V. Oppenheim and Ronald W. Schafer, the principles of signal processing can be found in the classical numerical analysis techniques of the 17th century. They further state that the digital refinement of these techniques can be found in the digital control systems of the 1940s and 1950s. In 1948, Claude Shannon wrote the influential paper "A Mathematical Theory of Communication" which was publis ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Quadrature Amplitude Modulation
Quadrature amplitude modulation (QAM) is the name of a family of digital modulation methods and a related family of analog modulation methods widely used in modern telecommunications to transmit information. It conveys two analog message signals, or two digital bit streams, by changing (''modulating'') the amplitudes of two carrier waves, using the amplitude-shift keying (ASK) digital modulation scheme or amplitude modulation (AM) analog modulation scheme. The two carrier waves are of the same frequency and are out of phase with each other by 90°, a condition known as orthogonality or Quadrature phase, quadrature. The transmitted signal is created by adding the two carrier waves together. At the receiver, the two waves can be coherently separated (demodulated) because of their orthogonality. Another key property is that the modulations are low-frequency/low-bandwidth waveforms compared to the carrier frequency, which is known as the In-phase and quadrature components#Narrowband ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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JPEG 2000
JPEG 2000 (JP2) is an image compression standard and coding system. It was developed from 1997 to 2000 by a Joint Photographic Experts Group committee chaired by Touradj Ebrahimi (later the JPEG president), with the intention of superseding their original JPEG standard (created in 1992), which is based on a discrete cosine transform (DCT), with a newly designed, wavelet-based method. The standardized filename extension is .jp2 for International Organization for Standardization, ISO/International Electrotechnical Commission, IEC 15444-1 conforming files and .jpx for the extended part-2 specifications, published as ISO/IEC 15444-2. The Internet media type, MIME types for JPEG 2000 are defined in RFC 3745. The MIME type for JPEG 2000 (ISO/IEC 15444-1) is image/jp2. The JPEG 2000 project was motivated by Ricoh, Ricoh's submission in 1995 of the CREW (Compression with Reversible Embedded Wavelets) algorithm to the standardization effort of JPEG LS. Ultimately the Lossless JPEG#LOCO-I_a ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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WavPack
WavPack is a free and open-source lossless audio compression format and application implementing the format. It is unique in the way that it supports hybrid audio compression alongside normal compression which is similar to how FLAC works. It also supports compressing a wide variety of lossless formats, including various variants of PCM and also DSD as used in SACDs, together with its support for surround audio. Features WavPack compression can compress (and losslessly restore) 8, 16, 24, and 32-bit fixed-point, and 32-bit floating-point PCM audio files in the . WAV file format. It can also handle DSD input in DSDIFF or DSF format. It also supports surround sound streams and high sampling rates. Like other lossless compression schemes, the data reduction rate varies with the source, but it is generally between 30% and 70% for typical popular music and somewhat better than that for classical music and other sources with greater dynamic range. Hybrid mode WavPack also ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Bitrate Peeling
Bitrate peeling is a technique used in Ogg Vorbis audio encoded streams, wherein a stream can be encoded at one bitrate but can be served at that or any lower bitrate. The purpose is to provide access to the clip for people with slower Internet connections, and yet still allow people with faster connections to enjoy the higher quality content. The server automatically chooses which stream to deliver to the user, depending on user's connection speed. , Ogg Vorbis bitrate peeling existed only as a concept as there was not yet an encoder capable of producing peelable datastreamBounties - XiphWiki Difference from other technologies The difference between SureStream and bitrate peeling is that SureStream is limited to only a handful of pre-defined bitrates, with significant difference between them, and SureStream encoded files are big because they contain all of the bitrates used, while bitrate peeling uses much smaller steps to change the available bitrate and quality, and only ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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DTS-HD Master Audio
DTS-HD Master Audio (DTS-HD MA; known as DTS++ before 2004) is a multi-channel, lossless audio codec developed by DTS as an extension of the lossy DTS Coherent Acoustics codec (DTS CA; usually itself referred to as just DTS). Rather than being an entirely new coding mechanism, DTS-HD MA encodes an audio master in lossy DTS first, then stores a concurrent stream of supplementary data representing whatever the DTS encoder discarded. This gives DTS-HD MA a lossy "core" able to be played back by devices that cannot decode the more complex lossless audio. DTS-HD MA's primary application is audio storage and playback for Blu-ray media; it competes in this respect with Dolby TrueHD, another lossless surround format. Specifications DTS-HD MA can store up to 8 discrete channels of audio ( 7.1 surround) at up to a 24 bit sample depth and 192 kHz sampling frequency (96 kHz for 6.1 or 7.1 surround). Although DTS-HD MA, and the related DTS-HD, allow virtually any number o ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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LCEVC
Low Complexity Enhancement Video Coding (LCEVC) is a International Organization for Standardization, ISO/International Electrotechnical Commission, IEC video coding standard developed by the Moving Picture Experts Group (MPEG) under the project name ''MPEG-5 Part 2 LCEVC''. Concept LCEVC specifies an enhancement layer which, when combined with a base video encoded with a separate codec, produces an enhanced video stream. The base layer is decodable by a hardware decoder, and the enhancement layer is suitable for software processing implementation with sustainable power consumption. The enhancement layer provides improved features to existing codecs, such as compression capability extension and lower encoding/decoding complexity, for live streaming or broadcasting applications. LCEVC leverages a base video codec (e.g., Advanced Video Coding, AVC, High Efficiency Video Coding, HEVC, VP9, AV1, Essential Video Coding, EVC or Versatile Video Coding, VVC) and employs an efficient low-c ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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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]   |
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High Efficiency Video Coding
High Efficiency Video Coding (HEVC), also known as H.265 and MPEG-H Part 2, is a video compression standard designed as part of the MPEG-H project as a successor to the widely used Advanced Video Coding (AVC, H.264, or MPEG-4 Part 10). In comparison to AVC, HEVC offers from 25% to 50% better data compression at the same level of video quality, or substantially improved video quality at the same bit rate. It supports resolutions up to 8192×4320, including 8K UHD, and unlike the primarily 8-bit AVC, HEVC's higher fidelity Main 10 profile has been incorporated into nearly all supporting hardware. While AVC uses the integer discrete cosine transform (DCT) with 4×4 and 8×8 block sizes, HEVC uses both integer DCT and discrete sine transform (DST) with varied block sizes between 4×4 and 32×32. The High Efficiency Image Format (HEIF) is based on HEVC. Concept In most ways, HEVC is an extension of the concepts in H.264/MPEG-4 AVC. Both work by comparing different parts of a fra ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Scalable Video Coding
Scalable Video Coding (SVC) is a video compression standard developed jointly by the ITU-T and the ISO/IEC. The two organizations formed the ''Joint Video Team'' (JVT) to create the H.264/ MPEG-4 AVC standard (ITU-T Rec. H.264 , ISO/IEC 14496-10 AVC). SVC aims to provide adaptable or ''scalable'' content, allowing a single encoded video stream to be decoded at various bitrates, resolutions, and quality levels, thus catering to diverse devices and network conditions. History In October 2003, the '' Moving Picture Experts Group'' (MPEG) issued a ''Call for Proposals on SVC Technology''. Fourteen proposals were submitted, twelve of which utilized wavelet compression, while the remaining two were extensions of H.264/MPEG-4 AVC. The proposal from the Heinrich-Hertz-Institut (HHI) was selected by MPEG as the foundation for the SVC standardization project. In January 2005, MPEG and the Video Coding Experts Group (VCEG) agreed to finalize SVC as an amendment to the H.264/MPEG-4 A ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Link Adaptation
Link adaptation, comprising adaptive coding and modulation (ACM) and others (such as Power Control), is a term used in wireless communications to denote the matching of the modulation, coding and other signal and protocol parameters to the conditions on the radio link (e.g. the pathloss, the interference due to signals coming from other transmitters, the sensitivity of the receiver, the available transmitter power margin, etc.). For example, WiMAX uses a rate adaptation algorithm that adapts the modulation and coding scheme (MCS) according to the quality of the radio channel, and thus the bit rate and robustness of data transmission. The process of link adaptation is a dynamic one and the signal and protocol parameters change as the radio link conditions change—for example in High-Speed Downlink Packet Access (HSDPA) in Universal Mobile Telecommunications System (UMTS) this can take place every 2 ms. Adaptive modulation systems invariably require some channel state informa ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Decibel
The decibel (symbol: dB) is a relative unit of measurement equal to one tenth of a bel (B). It expresses the ratio of two values of a Power, root-power, and field quantities, power or root-power quantity on a logarithmic scale. Two signals whose level (logarithmic quantity), levels differ by one decibel have a power ratio of 101/10 (approximately ) or root-power ratio of 101/20 (approximately ). The strict original usage above only expresses a relative change. However, the word decibel has since also been used for expressing an Absolute scale, absolute value that is relative to some fixed reference value, in which case the dB symbol is often suffixed with letter codes that indicate the reference value. For example, for the reference value of 1 volt, a common suffix is "#Voltage, V" (e.g., "20 dBV"). As it originated from a need to express power ratios, two principal types of scaling of the decibel are used to provide consistency depending on whether the scaling refer ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |