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104-420: It used dot-interlacing and digital video compression to deliver 1125 line, 60 field-per-second (1125i60) signals to the home. The system was standardized as ITU -R recommendation BO.786 and specified by SMPTE 260M, using a colorimetry matrix specified by SMPTE 240M. As with other analog systems, not all lines carry visible information. On MUSE there are 1035 active interlaced lines, therefore this system

208-433: A 40 dB of signal to noise ratio for a separate Y / C {\displaystyle Y/C} FM signal in the 22 GHz satellite band. This was feasible. There is one more power saving that appears from the character of the human eye. The lack of visual response to low frequency noise allows significant reduction in transponder power if the higher video frequencies are emphasized prior to modulation at

312-480: A MUSE receiver can retrieve the original RGB color components using the following matrix: The system used a colorimetry matrix specified by SMPTE 240M (with coefficients corresponding to the SMPTE RP 145 primaries, also known as SMPTE-C , in use at the time the standard was created). The chromaticity of the primary colors and white point are: The luma ( E Y {\displaystyle EY} ) function

416-513: A NHK-published book issued in the USA called Hi-Vision Technology . The DANCE audio codec was superseded by Dolby AC-3 (a.k.a. Dolby Digital ), DTS Coherent Acoustics (a.k.a. DTS Zeta 6x20 or ARTEC), MPEG-1 Layer III (a.k.a. MP3), MPEG-2 Layer I, MPEG-4 AAC and many other audio coders. The methods of this codec are described in the IEEE paper: Unlike traditional, interlaced video where interlacing

520-540: A composite FM signal in the 22 GHz band. This was incompatible with satellite broadcast techniques and bandwidth. To overcome this limitation, it was decided to use a separate transmission of Y {\displaystyle Y} and C {\displaystyle C} . This reduces the effective frequency range and lowers the required power. Approximately 570 W (360 for Y {\displaystyle Y} and 210 for C {\displaystyle C} ) would be needed in order to get

624-494: A form of LPC called adaptive predictive coding (APC), a perceptual coding algorithm that exploited the masking properties of the human ear, followed in the early 1980s with the code-excited linear prediction (CELP) algorithm which achieved a significant compression ratio for its time. Perceptual coding is used by modern audio compression formats such as MP3 and AAC . Discrete cosine transform (DCT), developed by Nasir Ahmed , T. Natarajan and K. R. Rao in 1974, provided

728-415: A further refinement of the direct use of probabilistic modelling , statistical estimates can be coupled to an algorithm called arithmetic coding . Arithmetic coding is a more modern coding technique that uses the mathematical calculations of a finite-state machine to produce a string of encoded bits from a series of input data symbols. It can achieve superior compression compared to other techniques such as

832-479: A given solid angle . The procedure for conversion from spectral radiance to luminance is standardized by the CIE and ISO . Brightness is the term for the subjective impression of the objective luminance measurement standard (see Objectivity (science) § Objectivity in measurement for the importance of this contrast). The SI unit for luminance is candela per square metre (cd/m ). A non-SI term for

936-537: A line by line basis as in traditional interlaced video which reduces only the vertical resolution to create each video field. Thus, in MUSE, only stationary images were transmitted at full resolution. However, as MUSE lowers the horizontal and vertical resolution of material that varies greatly from frame to frame, moving images were blurred. Because MUSE used motion-compensation, whole camera pans maintained full resolution, but individual moving elements could be reduced to only

1040-500: A linear tape speed of 805.2 mm/s and a writing speed at the heads of 51.5 m/s, are similar to Type C VTRs, have a head drum 135mm wide, 8 video playback, 8 video recording and 2 video erase heads, with 37 micron wide helical tracks. Output signal bandwidth is 30 Mhz of video bandwidth for luma (Y) and 15 Mhz of video bandwidth for chroma (P b , P r ). Audio is recorded with a sampling rate of 48 kHz stored at 16 bits per sample in linear tape tracks, sampling rate for luma

1144-438: A linear track. Unlike conventional type C videotape recorders, Vertical Blanking Intervals are not recorded on the tape. Helical tracks have groups of 4 signals or channels, arranged side by side and length-wise with red chrominance, blue chrominance, and two green chrominance signals with luminance information. Two tracks for green chrominance plus luminance are used to increase the bandwidth of these signals that can be recorded on

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1248-597: A lossily compressed file for some purpose usually produces a final result inferior to the creation of the same compressed file from an uncompressed original. In addition to sound editing or mixing, lossless audio compression is often used for archival storage, or as master copies. Lossy audio compression is used in a wide range of applications. In addition to standalone audio-only applications of file playback in MP3 players or computers, digitally compressed audio streams are used in most video DVDs, digital television, streaming media on

1352-520: A lossless medium, the luminance does not change along a given light ray . As the ray crosses an arbitrary surface S , the luminance is given by L v = d 2 Φ v d S d Ω S cos ⁡ θ S {\displaystyle L_{\mathrm {v} }={\frac {\mathrm {d} ^{2}\Phi _{\mathrm {v} }}{\mathrm {d} S\,\mathrm {d} \Omega _{S}\cos \theta _{S}}}} where More generally,

1456-400: A lossy format and a lossless correction; this allows stripping the correction to easily obtain a lossy file. Such formats include MPEG-4 SLS (Scalable to Lossless), WavPack , and OptimFROG DualStream . When audio files are to be processed, either by further compression or for editing , it is desirable to work from an unchanged original (uncompressed or losslessly compressed). Processing of

1560-526: A number of MUSE LaserDisc players available in Japan: Pioneer HLD-XØ, HLD-X9, HLD-1000, HLD-V500, HLD-V700; Sony HIL-1000, HIL-C1 and HIL-C2EX; the last two of which have OEM versions made by Panasonic, LX-HD10 and LX-HD20. Players also supported standard NTSC LaserDiscs. Hi-Vision LaserDiscs are extremely rare and expensive. The HDL-5800 Video Disc Recorder recorded both high definition still images and continuous video onto an optical disc and

1664-421: A number of companies because the inventor refuses to get invention patents for his work. He prefers declaring it of Public Domain publishing it Luminance Luminance is a photometric measure of the luminous intensity per unit area of light travelling in a given direction. It describes the amount of light that passes through, is emitted from, or is reflected from a particular area, and falls within

1768-450: A particular surface from a particular angle of view . Luminance is thus an indicator of how bright the surface will appear. In this case, the solid angle of interest is the solid angle subtended by the eye's pupil . Luminance is used in the video industry to characterize the brightness of displays. A typical computer display emits between 50 and 300 cd/m . The sun has a luminance of about 1.6 × 10  cd/m at noon. Luminance

1872-443: A quarter of the full frame resolution. Because the mix between motion and non-motion was encoded on a pixel-by-pixel basis, it wasn't as visible as most would think. Later, NHK came up with backwards compatible methods of MUSE encoding/decoding that greatly increased resolution in moving areas of the image as well as increasing the chroma resolution during motion. This so-called MUSE-III system was used for broadcasts starting in 1995 and

1976-402: A representation of digital data that can be decoded to an exact digital duplicate of the original. Compression ratios are around 50–60% of the original size, which is similar to those for generic lossless data compression. Lossless codecs use curve fitting or linear prediction as a basis for estimating the signal. Parameters describing the estimation and the difference between the estimation and

2080-590: A result, speech can be encoded at high quality using a relatively low bit rate. This is accomplished, in general, by some combination of two approaches: The earliest algorithms used in speech encoding (and audio data compression in general) were the A-law algorithm and the μ-law algorithm . Early audio research was conducted at Bell Labs . There, in 1950, C. Chapin Cutler filed the patent on differential pulse-code modulation (DPCM). In 1973, Adaptive DPCM (ADPCM)

2184-415: A signal similar in structure to the Y / C {\displaystyle Y/C} composite video NTSC signal - with the Y {\displaystyle Y} ( luminance ) at the lower frequencies and the C {\displaystyle C} ( chrominance ) above. Approximately 3 kW of power would be required, in order to get 40 dB of signal to noise ratio for

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2288-589: A signal to noise ratio of 41 dB. They accept luma and chroma signals with video bandwidths of up to 30 MHz for both. Video bandwidth is measured before FM modulation. Signals are recorded onto the tape using FM modulation. Linear tape speed is 483.1 mm/s and writing speed at the heads is 25.9 m/s. The head drum is 134.5 mm wide and has 4 video record heads, 4 video playback heads and 1 video erasing head. It could record for 45 minutes on 10.5 inch reels. These machines, unlike conventional type C VTRs, are incapable of showing images while paused or playing

2392-420: A similar system as a means of reducing bandwidth, but instead of static sampling, the actual ratio varies according to the amount of motion on the screen. In practice, MUSE sampling will vary from approximately 4:2:1 to 4:0.5:0.25, depending on the amount of movement. Thus the red-green chroma component C r {\displaystyle Cr} has between one-half and one-eighth the sampling resolution of

2496-526: A single helical track with 4 channels. In 1987, technical standards for digital recording of Hi-Vision signals were released by NHK, and Sony developed the HDD-1000 VTR as part of their HDVS line, and Hitachi developed the HV-1200 digital reel to reel VTR. Audio is recorded digitally similarly to a DASH ( Digital Audio Stationary Head ) digital audio recorder, but several changes were made to synchronize

2600-418: A special case of data differencing . Data differencing consists of producing a difference given a source and a target, with patching reproducing the target given a source and a difference. Since there is no separate source and target in data compression, one can consider data compression as data differencing with empty source data, the compressed file corresponding to a difference from nothing. This

2704-437: A very few of the last Hi-Vision MUSE LaserDiscs used it ( A River Runs Through It is one Hi-Vision LD that used it). During early demonstrations of the MUSE system, complaints were common about the decoder's large size, which led to the creation of a miniaturized decoder. Shadows and multipath still plague this analog frequency modulated transmission mode. Japan has since switched to a digital HDTV system based on ISDB , but

2808-406: A video system is usually expressed as a three part ratio. The three terms of the ratio are: the number of brightness (luma) Y {\displaystyle Y} samples , followed by the number of samples of the two color (chroma) components C b {\displaystyle Cb} and C r {\displaystyle Cr} , for each complete sample area. Traditionally

2912-618: A way similar to the way a digital camera records color images. The luminance of a specified point of a light source, in a specified direction, is defined by the mixed partial derivative L v = d 2 Φ v d Σ d Ω Σ cos ⁡ θ Σ {\displaystyle L_{\mathrm {v} }={\frac {\mathrm {d} ^{2}\Phi _{\mathrm {v} }}{\mathrm {d} \Sigma \,\mathrm {d} \Omega _{\Sigma }\cos \theta _{\Sigma }}}} where If light travels through

3016-772: A zip file's compressed size includes both the zip file and the unzipping software, since you can not unzip it without both, but there may be an even smaller combined form. Examples of AI-powered audio/video compression software include NVIDIA Maxine , AIVC. Examples of software that can perform AI-powered image compression include OpenCV , TensorFlow , MATLAB 's Image Processing Toolbox (IPT) and High-Fidelity Generative Image Compression. In unsupervised machine learning , k-means clustering can be utilized to compress data by grouping similar data points into clusters. This technique simplifies handling extensive datasets that lack predefined labels and finds widespread use in fields such as image compression . Data compression aims to reduce

3120-400: Is invariant in geometric optics . This means that for an ideal optical system, the luminance at the output is the same as the input luminance. For real, passive optical systems, the output luminance is at most equal to the input. As an example, if one uses a lens to form an image that is smaller than the source object, the luminous power is concentrated into a smaller area, meaning that

3224-499: Is 74.25 Mhz and 37.125 Mhz for chroma stored at 8 bits per sample. Signal to noise ratio is 56 dB for chroma and luma. Video fields are divided into 16 helical tracks on the tape. Total video bandwidth is 1.188 gigabits/s. Cue signals are recorded into 3 linear tape tracks. Video is recorded in groups of 4 tracks or channels, which are side by side length-wise within each helical track, to allow for parallelization: high total data rates with relatively low data rates per head, and reduce

Multiple sub-Nyquist sampling encoding - Misplaced Pages Continue

3328-483: Is a 1125 line system (1035 visible), and is not pulse and sync compatible with the digital 1080 line system used by modern HDTV. Originally, it was a 1125 line, interlaced, 60 Hz, system with a 5:3 (1.66:1) aspect ratio and an optimal viewing distance of roughly 3.3H. In 1989 this was changed to a 16:9 aspect ratio. For terrestrial MUSE transmission a bandwidth limited FM system was devised. A satellite transmission system uses uncompressed FM. Before MUSE compression,

3432-530: Is a 60 Hz TV system, not a 50 Hz system that is standard in Europe and the rest of the world (outside the Americas and Japan). The EBU development and deployment of B-MAC , D-MAC and much later on HD-MAC were made possible by Hi-Vision's technical success. In many ways MAC transmission systems are better than MUSE because of the total separation of colour from brightness in the time domain within

3536-650: Is distinguished as a separate discipline from general-purpose audio compression. Speech coding is used in internet telephony , for example, audio compression is used for CD ripping and is decoded by the audio players. Lossy compression can cause generation loss . The theoretical basis for compression is provided by information theory and, more specifically, Shannon's source coding theorem ; domain-specific theories include algorithmic information theory for lossless compression and rate–distortion theory for lossy compression. These areas of study were essentially created by Claude Shannon , who published fundamental papers on

3640-433: Is done on a line by line basis, showing either odd or even lines of video at any one time, thus requiring 2 fields of video to complete a video frame, MUSE used a four-field dot-interlacing cycle, meaning it took four fields to complete a single MUSE frame, and dot interlacing is interlacing that was done on a pixel by pixel basis, dividing both horizontal and vertical resolution by half to create each field of video, and not in

3744-411: Is on the order of 23 ms. Speech encoding is an important category of audio data compression. The perceptual models used to estimate what aspects of speech a human ear can hear are generally somewhat different from those used for music. The range of frequencies needed to convey the sounds of a human voice is normally far narrower than that needed for music, and the sound is normally less complex. As

3848-420: Is perceptually irrelevant, most lossy compression algorithms use transforms such as the modified discrete cosine transform (MDCT) to convert time domain sampled waveforms into a transform domain, typically the frequency domain . Once transformed, component frequencies can be prioritized according to how audible they are. Audibility of spectral components is assessed using the absolute threshold of hearing and

3952-426: Is processed. In the minimum case, latency is zero samples (e.g., if the coder/decoder simply reduces the number of bits used to quantize the signal). Time domain algorithms such as LPC also often have low latencies, hence their popularity in speech coding for telephony. In algorithms such as MP3, however, a large number of samples have to be analyzed to implement a psychoacoustic model in the frequency domain, and latency

4056-429: Is reduced, using methods such as coding , quantization , DCT and linear prediction to reduce the amount of information used to represent the uncompressed data. Lossy audio compression algorithms provide higher compression and are used in numerous audio applications including Vorbis and MP3 . These algorithms almost all rely on psychoacoustics to eliminate or reduce fidelity of less audible sounds, thereby reducing

4160-463: 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 is 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 ,

4264-505: Is sometimes also mentioned as 1035i . MUSE employed 2-dimensional filtering, dot-interlacing, motion-vector compensation and line-sequential color encoding with time compression to "fold" or compress an original 30 MHz bandwidth Hi-Vision source signal into just 8.1 MHz. Japan began broadcasting wideband analog HDTV signals in December 1988, initially with an aspect ratio of 2:1. The Sony HDVS high-definition video system

Multiple sub-Nyquist sampling encoding - Misplaced Pages Continue

4368-428: Is specified as: The blue color difference ( E P B {\displaystyle EPB} ) is amplitude-scaled ( E B − E Y {\displaystyle EB-EY} ), according to: The red color difference ( E P R {\displaystyle EPR} ) is amplitude-scaled ( E R − E Y {\displaystyle ER-EY} ), according to: MUSE

4472-431: 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

4576-402: Is the same as considering absolute entropy (corresponding to data compression) as a special case of relative entropy (corresponding to data differencing) with no initial data. The term differential compression is used to emphasize the data differencing connection. Entropy coding originated in the 1940s with the introduction of Shannon–Fano coding , the basis for Huffman coding which

4680-435: Is used in digital cameras , to increase storage capacities. Similarly, DVDs , Blu-ray and streaming video use lossy video coding formats . Lossy compression is extensively used in video. In lossy audio compression, methods of psychoacoustics are used to remove non-audible (or less audible) components of the audio signal . Compression of human speech is often performed with even more specialized techniques; speech coding

4784-685: Is used in the GIF format, introduced in 1987. DEFLATE , a lossless compression algorithm specified in 1996, is used in the Portable Network Graphics (PNG) format. Wavelet compression , the use of wavelets in image compression, began after the development of DCT coding. The JPEG 2000 standard was introduced in 2000. In contrast to the DCT algorithm used by the original JPEG format, JPEG 2000 instead uses discrete wavelet transform (DWT) algorithms. JPEG 2000 technology, which includes

4888-630: The Internet , satellite and cable radio, and increasingly in terrestrial radio broadcasts. Lossy compression typically achieves far greater compression than lossless compression, by discarding less-critical data based on psychoacoustic optimizations. Psychoacoustics recognizes that not all data in an audio stream can be perceived by the human auditory system . Most lossy compression reduces redundancy by first identifying perceptually irrelevant sounds, that is, sounds that are very hard to hear. Typical examples include high frequencies or sounds that occur at

4992-462: The Lempel–Ziv–Welch (LZW) algorithm rapidly became the method of choice for most general-purpose compression systems. LZW is used in GIF images, programs such as PKZIP , and hardware devices such as modems. LZ methods use a table-based compression model where table entries are substituted for repeated strings of data. For most LZ methods, this table is generated dynamically from earlier data in

5096-507: The Motion JPEG 2000 extension, was selected as the video coding standard for digital cinema in 2004. Audio data compression, not to be confused with dynamic range compression , has the potential to reduce the transmission bandwidth and storage requirements of audio data. Audio compression formats compression algorithms are implemented in software as audio codecs . In both lossy and lossless compression, information redundancy

5200-476: The University of Buenos Aires . In 1983, using the psychoacoustic principle of the masking of critical bands first published in 1967, he started developing a practical application based on the recently developed IBM PC computer, and the broadcast automation system was launched in 1987 under the name Audicom . 35 years later, almost all the radio stations in the world were using this technology manufactured by

5304-505: The discrete cosine transform (DCT). It was first proposed in 1972 by Nasir Ahmed , who then developed a working algorithm with T. Natarajan and K. R. Rao in 1973, before introducing it in January 1974. DCT is the most widely used lossy compression method, and is used in multimedia formats for images (such as JPEG and HEIF ), video (such as MPEG , AVC and HEVC) and audio (such as MP3 , AAC and Vorbis ). Lossy image compression

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5408-517: The illuminance is higher at the image. The light at the image plane, however, fills a larger solid angle so the luminance comes out to be the same assuming there is no loss at the lens. The image can never be "brighter" than the source. Retinal damage can occur when the eye is exposed to high luminance. Damage can occur because of local heating of the retina. Photochemical effects can also cause damage, especially at short wavelengths. The IEC 60825 series gives guidance on safety relating to exposure of

5512-506: The linear predictive coding (LPC) used with speech, are source-based coders. LPC uses a model of the human vocal tract to analyze speech sounds and infer the parameters used by the model to produce them moment to moment. These changing parameters are transmitted or stored and used to drive another model in the decoder which reproduces the sound. Lossy formats are often used for the distribution of streaming audio or interactive communication (such as in cell phone networks). In such applications,

5616-610: The probability distribution of the input data. An early example of the use of arithmetic coding was in an optional (but not widely used) feature of the JPEG image coding standard. It has since been applied in various other designs including H.263 , H.264/MPEG-4 AVC and HEVC for video coding. Archive software typically has the ability to adjust the "dictionary size", where a larger size demands more random-access memory during compression and decompression, but compresses stronger, especially on repeating patterns in files' content. In

5720-516: The 1980s as a compression system for Hi-Vision HDTV signals. MUSE's "1125 lines" are an analog measurement, which includes non-video scan lines taking place while a CRT 's electron beam returns to the top of the screen to begin scanning the next field. Only 1035 lines have picture information. Digital signals count only the lines (rows of pixels) that have actual detail, so NTSC's 525 lines become 486i (rounded to 480 to be MPEG compatible), PAL's 625 lines become 576i, and MUSE would be 1035i. To convert

5824-462: The Hi- Vision signal bandwidth is reduced from 30 MHz for luminance and chrominance to a pre-compression bandwidth Y {\displaystyle Y} of 20 MHz for luminance, and a pre-compression bandwidth for chrominance is a 7.425 MHz carrier. The Japanese initially explored the idea of frequency modulation of a conventionally constructed composite signal. This would create

5928-581: The MAC signal structure. Like Hi-Vision, HD-MAC could not be transmitted in 8 MHz channels without substantial modification – and a severe loss of quality and frame rate. A 6 MHz version Hi-Vision was experimented with in the US, but it too had severe quality problems so the FCC never fully sanctioned its use as a domestic terrestrial television transmission standard. The US ATSC working group that had led to

6032-708: The MUSE system: The MUSE luminance signal Y {\displaystyle Y} encodes Y M {\displaystyle YM} , specified as the following mix of the original RGB color channels: The chrominance C {\displaystyle C} signal encodes B − Y M {\displaystyle B-YM} and R − Y M {\displaystyle R-YM} difference signals. By using these three signals ( Y M {\displaystyle YM} , B − Y M {\displaystyle B-YM} and R − Y M {\displaystyle R-YM} ),

6136-518: The actual signal are coded separately. A number of lossless audio compression formats exist. See list of lossless codecs for a listing. Some formats are associated with a distinct system, such as Direct Stream Transfer , used in Super Audio CD and Meridian Lossless Packing , used in DVD-Audio , Dolby TrueHD , Blu-ray and HD DVD . Some audio file formats feature a combination of

6240-403: The amount of data required to represent an image at the cost of a relatively small reduction in image quality and has become the most widely used image file format . Its highly efficient DCT-based compression algorithm was largely responsible for the wide proliferation of digital images and digital photos . Lempel–Ziv–Welch (LZW) is a lossless compression algorithm developed in 1984. It

6344-438: The audio to the video. These digital VTRs can record 8 channels of digital audio on linear tracks (horizontally along the entire length of the tape). According to the standards, these VTRs operate with a head drum speed of 7200 RPM to accommodate the higher signal bandwidths of digital signal modulation on the tape which is also accommodated with the use of metal alloy particle tape, have a bit rate of 148.5 Mbit/s per video head,

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6448-571: The bandwidth of Hi-Vision MUSE into "conventional" lines-of-horizontal resolution (as is used in the NTSC world), multiply 29.9 lines per MHz of bandwidth. (NTSC and PAL/SECAM are 79.9 lines per MHz) - this calculation of 29.9 lines works for all current HD systems including Blu-ray and HD-DVD. So, for MUSE, during a still picture, the lines of resolution would be: 598-lines of luminance resolution per-picture-height. The chroma resolution is: 209-lines. The horizontal luminance measurement approximately matches

6552-418: The basis for the modified discrete cosine transform (MDCT) used by modern audio compression formats such as MP3, Dolby Digital , and AAC. MDCT was proposed by J. P. Princen, A. W. Johnson and A. B. Bradley in 1987, following earlier work by Princen and Bradley in 1986. The world's first commercial broadcast automation audio compression system was developed by Oscar Bonello, an engineering professor at

6656-487: The better-known Huffman algorithm. It uses an internal memory state to avoid the need to perform a one-to-one mapping of individual input symbols to distinct representations that use an integer number of bits, and it clears out the internal memory only after encoding the entire string of data symbols. Arithmetic coding applies especially well to adaptive data compression tasks where the statistics vary and are context-dependent, as it can be easily coupled with an adaptive model of

6760-410: The coding algorithm can be critical; for example, when there is a two-way transmission of data, such as with a telephone conversation, significant delays may seriously degrade the perceived quality. In contrast to the speed of compression, which is proportional to the number of operations required by the algorithm, here latency refers to the number of samples that must be analyzed before a block of audio

6864-480: The computational resources or time required to compress and decompress the data. Lossless data compression algorithms usually exploit statistical redundancy to represent data without losing any information , so that the process is reversible. Lossless compression is possible because most real-world data exhibits statistical redundancy. For example, an image may have areas of color that do not change over several pixels; instead of coding "red pixel, red pixel, ..."

6968-629: The contents in the time dimension, in other words transmitting frames of video that are divided into regions with chrominance compressed into the left of the frame and luminance compressed into the right of the frame, which must then be expanded and layered to create a visible image. This makes it different from NTSC which carries luminance, audio and chrominance simultaneously in several carrier frequencies. Hi-Vision signals are analog component video signals with 3 channels which were RGB initially, and later YP b P r . The Hi-Vision standard aims to work with both RGB and YP b P r signals. Key features of

7072-660: The core information of the original data while significantly decreasing the required storage space. Large language models (LLMs) are also capable of lossless data compression, as demonstrated by DeepMind 's research with the Chinchilla 70B model. Developed by DeepMind, Chinchilla 70B effectively compressed data, outperforming conventional methods such as Portable Network Graphics (PNG) for images and Free Lossless Audio Codec (FLAC) for audio. It achieved compression of image and audio data to 43.4% and 16.4% of their original sizes, respectively. Data compression can be viewed as

7176-526: The creation of NTSC in the 1950s was reactivated in the early 1990s because of Hi-Vision's success. Many aspects of the DVB standard are based on work done by the ATSC working group, however most of the impact is in support for 60 Hz (as well as 24 Hz for film transmission) and uniform sampling rates and interoperable screen sizes. On May 20, 1994, Panasonic released the first MUSE LaserDisc player. There were

7280-467: The data in question. For example, the human eye is more sensitive to subtle variations in luminance than it is to the variations in color. JPEG image compression works in part by rounding off nonessential bits of information. A number of popular compression formats exploit these perceptual differences, including psychoacoustics for sound, and psychovisuals for images and video. Most forms of lossy compression are based on transform coding , especially

7384-439: The data may be encoded as "279 red pixels". This is a basic example of run-length encoding ; there are many schemes to reduce file size by eliminating redundancy. The Lempel–Ziv (LZ) compression methods are among the most popular algorithms for lossless storage. DEFLATE is a variation on LZ optimized for decompression speed and compression ratio, but compression can be slow. In the mid-1980s, following work by Terry Welch ,

7488-462: The data must be decompressed as the data flows, rather than after the entire data stream has been transmitted. Not all audio codecs can be used for streaming applications. Latency is introduced by the methods used to encode and decode the data. Some codecs will analyze a longer segment, called a frame , of the data to optimize efficiency, and then code it in a manner that requires a larger segment of data at one time to decode. The inherent latency of

7592-530: The deployment of MUSE) it became possible for this television system to be transmitted by Ku Band satellite technology by the end of the 1980s. The US FCC in the late 1980s began to issue directives that would allow MUSE to be tested in the US, providing it could be fit into a 6 MHz System-M channel. The Europeans (in the form of the European Broadcasting Union (EBU)) were impressed with MUSE, but could never adopt it because it

7696-462: The eye to lasers, which are high luminance sources. The IEC 62471 series gives guidance for evaluating the photobiological safety of lamps and lamp systems including luminaires. Specifically it specifies the exposure limits, reference measurement technique and classification scheme for the evaluation and control of photobiological hazards from all electrically powered incoherent broadband sources of optical radiation, including LEDs but excluding lasers, in

7800-469: The file size is reduced to 5-20% of the original size and a megabyte can store about a minute's worth of music at adequate quality. Several proprietary lossy compression algorithms have been developed that provide higher quality audio performance by using a combination of lossless and lossy algorithms with adaptive bit rates and lower compression ratios. Examples include aptX , LDAC , LHDC , MQA and SCL6 . To determine what information in an audio signal

7904-463: The first MUSE LaserDisc player. There were also a number of players available from other brands like Pioneer and Sony . Hi-Vision continued broadcasting in analog by NHK until 2007. Other channels had stopped soon after December 1, 2000 as they transitioned to digital HD signals in ISDB, Japan's digital broadcast standard. MUSE was developed by NHK Science & Technology Research Laboratories in

8008-693: The input. The table itself is often Huffman encoded . Grammar-based codes like this can compress highly repetitive input extremely effectively, for instance, a biological data collection of the same or closely related species, a huge versioned document collection, internet archival, etc. The basic task of grammar-based codes is constructing a context-free grammar deriving a single string. Other practical grammar compression algorithms include Sequitur and Re-Pair . The strongest modern lossless compressors use probabilistic models, such as prediction by partial matching . The Burrows–Wheeler transform can also be viewed as an indirect form of statistical modelling. In

8112-454: The integral covers all the directions of emission Ω Σ , In the case of a perfectly diffuse reflector (also called a Lambertian reflector ), the luminance is isotropic, per Lambert's cosine law . Then the relationship is simply L v = E v R π . {\displaystyle L_{\text{v}}={\frac {E_{\text{v}}R}{\pi }}.} A variety of units have been used for luminance, besides

8216-455: The late 1980s, digital images became more common, and standards for lossless image compression emerged. In the early 1990s, lossy compression methods began to be widely used. In these schemes, some loss of information is accepted as dropping nonessential detail can save storage space. There is a corresponding trade-off between preserving information and reducing size. Lossy data compression schemes are designed by research on how people perceive

8320-504: The linear tape speed. Digital video signals are recorded line by line (1 row of pixels in every frame of video or 1 line of video at a time) with ECC (Error Correcting Code) at the end of each line and in between a number of vertical lines. Reed-Solomon code is used for ECC and each line also has an ID number for trick play such as slow motion and picture search/shuttle. Digital video compression In information theory , data compression , source coding , or bit-rate reduction

8424-423: The luma component Y {\displaystyle Y} , and the blue-yellow chroma C b {\displaystyle Cb} has half the resolution of red-green. MUSE had a discrete 2- or 4-channel digital audio system called " DANCE ", which stood for Digital Audio Near-instantaneous Compression and Expansion . It used differential audio transmission ( differential pulse-code modulation ) that

8528-759: The luminance along a light ray can be defined as L v = n 2 d Φ v d G {\displaystyle L_{\mathrm {v} }=n^{2}{\frac {\mathrm {d} \Phi _{\mathrm {v} }}{\mathrm {d} G}}} where The luminance of a reflecting surface is related to the illuminance it receives: ∫ Ω Σ L v d Ω Σ cos ⁡ θ Σ = M v = E v R , {\displaystyle \int _{\Omega _{\Sigma }}L_{\text{v}}\mathrm {d} \Omega _{\Sigma }\cos \theta _{\Sigma }=M_{\text{v}}=E_{\text{v}}R,} where

8632-479: The means for mapping data onto a signal. Data Compression algorithms present a space-time complexity trade-off between the bytes needed to store or transmit information, and the Computational resources needed to perform the encoding and decoding. The design of data compression schemes involves balancing the degree of compression, the amount of distortion introduced (when using lossy data compression ), and

8736-468: The original MUSE-based BS Satellite channel 9 (NHK BS Hi-vision) was broadcast until September 30, 2007. MUSE, as the US public came to know it, was initially covered in the magazine Popular Science in the mid-1980s. The US television networks did not provide much coverage of MUSE until the late 1980s, as there were few public demonstrations of the system outside Japan. Because Japan had its own domestic frequency allocation tables (that were more open to

8840-473: The principles of simultaneous masking —the phenomenon wherein a signal is masked by another signal separated by frequency—and, in some cases, temporal masking —where a signal is masked by another signal separated by time. Equal-loudness contours may also be used to weigh the perceptual importance of components. Models of the human ear-brain combination incorporating such effects are often called psychoacoustic models . Other types of lossy compressors, such as

8944-488: The same time as louder sounds. Those irrelevant sounds are coded with decreased accuracy or not at all. Due to the nature of lossy algorithms, audio quality suffers a digital generation loss when a file is decompressed and recompressed. This makes lossy compression unsuitable for storing the intermediate results in professional audio engineering applications, such as sound editing and multitrack recording. However, lossy formats such as MP3 are very popular with end-users as

9048-516: The same unit is the nit . The unit in the Centimetre–gram–second system of units (CGS) (which predated the SI system) is the stilb , which is equal to one candela per square centimetre or 10 kcd/m . Luminance is often used to characterize emission or reflection from flat, diffuse surfaces. Luminance levels indicate how much luminous power could be detected by the human eye looking at

9152-546: The size of data files, enhancing storage efficiency and speeding up data transmission. K-means clustering, an unsupervised machine learning algorithm, is employed to partition a dataset into a specified number of clusters, k, each represented by the centroid of its points. This process condenses extensive datasets into a more compact set of representative points. Particularly beneficial in image and signal processing , k-means clustering aids in data reduction by replacing groups of data points with their centroids, thereby preserving

9256-595: The space required to store or transmit them. The acceptable trade-off between loss of audio quality and transmission or storage size depends upon the application. For example, one 640 MB compact disc (CD) holds approximately one hour of uncompressed high fidelity music, less than 2 hours of music compressed losslessly, or 7 hours of music compressed in the MP3 format at a medium bit rate . A digital sound recorder can typically store around 200 hours of clearly intelligible speech in 640 MB. Lossless audio compression produces

9360-511: The symbol that compresses best, given the previous history). This equivalence has been used as a justification for using data compression as a benchmark for "general intelligence". An alternative view can show compression algorithms implicitly map strings into implicit feature space vectors , and compression-based similarity measures compute similarity within these feature spaces. For each compressor C(.) we define an associated vector space ℵ, such that C(.) maps an input string x, corresponding to

9464-419: The tape at low speeds. However they may be equipped with a frame store to capture images and display them while fast forwarding or rewinding the tape. The video heads are made of Mn-Zn ferrite material, those used for recording have a gap of 0.7 microns and a width of 80 microns and those for playback have a gap of 0.35 microns and a width of 70 microns. It records audio on 3 linear tracks, and control signals on

9568-453: The tape. Each of these 4 signals have a video bandwidth of 10 MHz. The VTR uses Iron metal oxide tape with cobalt for high coercivity, with capacity for 40 MHz of bandwidth at a head drum speed of 3600 RPM, which is sufficient for applying FM modulation to 10 MHz signals. To record 4 channels simultaneously in a single helical track, a separate, independent video head is required for each channel, and 4 video heads are grouped together which make

9672-478: The topic in the late 1940s and early 1950s. Other topics associated with compression include coding theory and statistical inference . There is a close connection between machine learning and compression. A system that predicts the posterior probabilities of a sequence given its entire history can be used for optimal data compression (by using arithmetic coding on the output distribution). Conversely, an optimal compressor can be used for prediction (by finding

9776-473: The transmitter and then de-emphasized at the receiver. This method was adopted, with crossover frequencies for the emphasis/de-emphasis at 5.2 MHz for Y {\displaystyle Y} and 1.6 MHz for C {\displaystyle C} . With this in place, the power requirements drop to 260 W of power (190 for Y {\displaystyle Y} and 69 for C {\displaystyle C} ). The subsampling in

9880-429: The value for brightness is always 4, with the rest of the values scaled accordingly. A sampling of 4:4:4 indicates that all three components are fully sampled. A sampling of 4:2:0, for example, indicated that the two chroma components are sampled at half the horizontal sample rate of luma - the horizontal chroma resolution is halved. This reduces the bandwidth of an uncompressed video signal by one-third. MUSE implements

9984-509: The vector norm ||~x||. An exhaustive examination of the feature spaces underlying all compression algorithms is precluded by space; instead, feature vectors chooses to examine three representative lossless compression methods, LZW, LZ77, and PPM. According to AIXI theory, a connection more directly explained in Hutter Prize , the best possible compression of x is the smallest possible software that generates x. For example, in that model,

10088-566: The vertical resolution of a 1080 interlaced image when the Kell factor and interlace factor are taken into account. 1125 lines was selected as a compromise between the resolution in lines of NTSC and PAL and then doubling this number. MUSE employs time-compression integration (TCI) which is another term for time-division multiplexing, which is used to carry luminance, chrominance, PCM audio and sync signals on one carrier signal/in one carrier frequency. However, TCI achieves multiplexing by compression of

10192-509: The wavelength range from 200 nm through 3000 nm . This standard was prepared as Standard CIE S 009:2002 by the International Commission on Illumination. A luminance meter is a device used in photometry that can measure the luminance in a particular direction and with a particular solid angle . The simplest devices measure the luminance in a single direction while imaging luminance meters measure luminance in

10296-605: Was a full band high definition video disc player. For recording Hi-Vision signals, Three reel to reel analog VTRs were released, among them are the Sony HDV-1000 part of their HDVS line, the NEC TT 8-1000 and the Toshiba TVR-1000. These analog VTRs had a head drum angular speed of 3600 RPM and are similar to Type C VTRs. They output a video bandwidth of 30 MHz for luma and 7 MHz for both chroma channels each, with

10400-609: Was developed in 1950. Transform coding dates back to the late 1960s, with the introduction of fast Fourier transform (FFT) coding in 1968 and the Hadamard transform in 1969. An important image compression technique is the discrete cosine transform (DCT), a technique developed in the early 1970s. DCT is the basis for JPEG, a lossy compression format which was introduced by the Joint Photographic Experts Group (JPEG) in 1992. JPEG greatly reduces

10504-425: Was introduced by P. Cummiskey, Nikil S. Jayant and James L. Flanagan . Perceptual coding was first used for speech coding compression, with linear predictive coding (LPC). Initial concepts for LPC date back to the work of Fumitada Itakura ( Nagoya University ) and Shuzo Saito ( Nippon Telegraph and Telephone ) in 1966. During the 1970s, Bishnu S. Atal and Manfred R. Schroeder at Bell Labs developed

10608-505: Was not psychoacoustics-based like MPEG-1 Layer II . It used a fixed transmission rate of 1350 kbp/s. Like the PAL NICAM stereo system, it used near-instantaneous companding (as opposed to Syllabic-companding like the dbx system uses) and non-linear 13-bit digital encoding at a 32 kHz sample rate . It could also operate in a 48 kHz 16-bit mode. The DANCE system was well documented in numerous NHK technical papers and in

10712-601: Was part of the early analog wideband Sony HDVS high-definition video system which supported the MUSE system. Capable of recording HD still images and video onto either the WHD-3AL0 or the WHD-33A0 optical disc; WHD-3Al0 for CLV mode (up to 10 minute video or 18,000 still frames per side); WHD-33A0 for CAV mode (up to 3 minute video or 5400 still frames per side). These video discs were used for short video content such as advertisements and product demonstrations. The HDL-2000

10816-576: Was used to create content for the MUSE system, but didn't record MUSE signals. It recorded Hi-Vision signals which are uncompressed. By the time of its commercial launch in 1991, digital HDTV was already under development in the United States . Hi-Vision MUSE was mainly broadcast by NHK through their BShi satellite TV channel, although other channels such as WOWOW, TV Asahi, Fuji Television, TBS Television, Nippon Television, and TV Tokyo also broadcast in MUSE. On May 20, 1994, Panasonic released

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