Super Audio CD ( SACD ) is an optical disc format for audio storage introduced in 1999. It was developed jointly by Sony and Philips Electronics and intended to be the successor to the compact disc (CD) format.
115-403: The SACD format allows multiple audio channels (i.e. surround sound or multichannel sound). It also provides a higher bit rate and longer playing time than a conventional CD. An SACD is designed to be played on an SACD player. A hybrid SACD contains a Compact Disc Digital Audio (CDDA) layer and can also be played on a standard CD player. The Super Audio CD format was introduced in 1999, and
230-639: A DSD copy of the HD stream. Sound quality parameters achievable by the Red Book CD-DA and SACD formats compared with the limits of human hearing are as follows: In September 2007, the Audio Engineering Society published the results of a year-long trial, in which a range of subjects—including professional recording engineers—were asked to discern the difference between high-resolution audio sources (including SACD and DVD-Audio ) and
345-443: A frequency response of 20 kHz can be achieved along with a dynamic range of nearly 120 dB, which is about the same dynamic range as PCM audio with a resolution of 20 bits. To reduce the space and bandwidth requirements of DSD, a lossless data compression method called Direct Stream Transfer ( DST ) is used. DST compression is compulsory for multi-channel regions and optional for stereo regions. It typically compresses by
460-403: A normal lens for a 35 mm camera with a focal length of f = 50 mm. To focus a distant object ( s 1 ≈ ∞ ), the rear principal plane of the lens must be located a distance s 2 = 50 mm from the film plane, so that it is at the location of the image plane. To focus an object 1 m away ( s 1 = 1,000 mm), the lens must be moved 2.6 mm farther away from
575-474: A subwoofer , whose position is not critical. Though cinema and soundtracks represent the major uses of surround techniques, its scope of application is broader than that, as surround sound permits creation of an audio-environment for all sorts of purposes. Multichannel audio techniques may be used to reproduce contents as varied as music, speech, natural or synthetic sounds for cinema, television , broadcasting, or computers. In terms of music content for example,
690-461: A thin lens in air, a positive focal length is the distance over which initially collimated (parallel) rays are brought to a focus , or alternatively a negative focal length indicates how far in front of the lens a point source must be located to form a collimated beam. For more general optical systems, the focal length has no intuitive meaning; it is simply the inverse of the system's optical power. In most photography and all telescopy , where
805-1137: A 2014 study, however, Marui et al. found that under double-blind conditions, listeners were able to distinguish between PCM (192 kHz/24 bits) and DSD (2.8 MHz) or DSD (5.6 MHz) recording formats, preferring the qualitative features of DSD, but could not discriminate between the two DSD formats. The Sony SCD-1 player was introduced concurrently with the SACD format in 1999, at a price of approximately US$ 5,000. It weighed over 26 kilograms (57 lb) and played two-channel SACDs and Red Book CDs only. Electronics manufacturers, including Onkyo , Denon , Marantz , Pioneer and Yamaha offer or offered SACD players. Sony has made in-car SACD players. In order to play back SACD content digitally without any conversion, some players are able to offer an output carrying encrypted streams of DSD, either via IEEE 1394 or more commonly, HDMI . SACD players are not permitted to offer an output carrying an unencrypted stream of DSD. The first two generations of Sony's PlayStation 3 game console were capable of reading SACD discs. Starting with
920-441: A 3-channel setup (LCR), as many of these techniques already contain a center microphone or microphone pair. Microphone techniques for LCR should, however, try to obtain greater channel separation to prevent conflicting phantom images between L/C and L/R for example. Specialised techniques have therefore been developed for 3-channel stereo. Surround microphone techniques largely depend on the setup used, therefore being biased towards
1035-455: A Decca Tree and two surround microphones. Two additional omnidirectional outriggers can be added to enlarge the perceived size of the orchestra or to better integrate the front and surround channels. The L, R, LS and RS microphones should be placed in a square formation, with L/R and LS/RS angled at 45 degrees and 135 degrees from the center microphone respectively. Spacing between these microphones should be about 1.8 meters. This square formation
1150-404: A PC is possible through freeware audio player foobar2000 for Windows using an open source plug-in extension called SACDDecoder . macOS music software Audirvana also supports playback of SACD disc images. Surround sound Surround sound is a technique for enriching the fidelity and depth of sound reproduction by using multiple audio channels from speakers that surround
1265-408: A baffle is used for separation between the front left and right channels, which are 30 cm apart. Outrigger omnidirectional microphones, low-pass filtered at 250 Hz, are spaced 3 meters apart in line with the L and R cardioids. These compensate for the bass roll-off of the cardioid microphones and also add expansiveness. A 3-meter spaced microphone pair, situated 2–3 meters behind front array,
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#17327731253531380-412: A beam of collimated light will be focused to a single spot. For a diverging lens (for example a concave lens ), the focal length is negative and is the distance to the point from which a collimated beam appears to be diverging after passing through the lens. When a lens is used to form an image of some object, the distance from the object to the lens u , the distance from the lens to the image v , and
1495-421: A compact disc audio (44.1 kHz/16 bit) conversion of the same source material under double-blind test conditions. Out of 554 trials, there were 276 correct answers, a 49.8% success rate corresponding almost exactly to the 50% that would have been expected by chance guessing alone. When the level of the signal was elevated by 14 dB or more, the test subjects were able to detect the higher noise floor of
1610-597: A convex mirror. In the sign convention used in optical design, a concave mirror has negative radius of curvature, so f = − R 2 , {\displaystyle f=-{R \over 2},} where R is the radius of curvature of the mirror's surface. See Radius of curvature (optics) for more information on the sign convention for radius of curvature used here. Camera lens focal lengths are usually specified in millimetres (mm), but some older lenses are marked in centimetres (cm) or inches. Focal length ( f ) and field of view (FOV) of
1725-796: A factor of between two and three, allowing a disc to contain 80 minutes of both 2-channel and 5.1-channel sound. Direct Stream Transfer compression was standardized as an amendment to the MPEG-4 Audio standard, ISO/IEC 14496-3:2001/Amd 6:2005 (Lossless coding of oversampled audio), in 2005. It contains the DSD and DST definitions as described in the Super Audio CD Specification. The MPEG-4 DST provides lossless coding of oversampled audio signals. Target applications of DST are archiving and storage of 1-bit oversampled audio signals and SA-CD. A reference implementation of MPEG-4 DST
1840-509: A fixed or forward perspective of the sound field to the listener at this location. Surround sound formats vary in reproduction and recording methods, along with the number and positioning of additional channels. The most common surround sound specification, the ITU 's 5.1 standard , calls for 6 speakers: Center (C), in front of the listener; Left (L) and Right (R), at angles of 60°; Left Surround (LS) and Right Surround (RS) at angles of 100–120°; and
1955-624: A full-frequency range and, as such, there is no need for an LFE in surround music production, because all the frequencies are available in all the main channels. These labels sometimes use the LFE channel to carry a height channel. The label BIS Records generally uses a 5.0 channel mix. Channel notation indicates the number of discrete channels encoded in the audio signal, not necessarily the number of channels reproduced for playback. The number of playback channels can be increased by using matrix decoding . The number of playback channels may also differ from
2070-617: A given angle of view, by a factor known as the crop factor . The optical power of a lens or curved mirror is a physical quantity equal to the reciprocal of the focal length, expressed in metres . A dioptre is its unit of measurement with dimension of reciprocal length , equivalent to one reciprocal metre , 1 dioptre = 1 m . For example, a 2-dioptre lens brings parallel rays of light to focus at 1 ⁄ 2 metre. A flat window has an optical power of zero dioptres, as it does not cause light to converge or diverge. The main benefit of using optical power rather than focal length
2185-414: A halls, side reflections are essential. Appropriate microphone techniques should therefore be used, if room impression is important. Although the reproduction of side images are very unstable in the 5.1 surround setup, room impressions can still be accurately presented. Some microphone techniques used for coverage of three front channels, include double-stereo techniques, INA-3 (Ideal Cardioid Arrangement),
2300-403: A lens are inversely proportional. For a standard rectilinear lens , F O V = 2 arctan ( x 2 f ) {\textstyle \mathrm {FOV} =2\arctan {\left({x \over 2f}\right)}} , where x is the width of the film or imaging sensor. When a photographic lens is set to "infinity", its rear principal plane is separated from
2415-422: A lens is defined as the point at which the spreading beams of light meet when they are extended backwards. No image is formed during such a test, and the focal length must be determined by passing light (for example, the light of a laser beam) through the lens, examining how much that light becomes dispersed/ bent, and following the beam of light backwards to the lens's focal point. For a thick lens (one which has
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#17327731253532530-399: A live performance may use multichannel techniques in the context of an open-air concert, of a musical theatre performance or for broadcasting ; for a film , specific techniques are adapted to movie theater or to home (e.g. home cinema systems). The narrative space is also a content that can be enhanced through multichannel techniques. This applies mainly to cinema narratives, for example
2645-406: A master of We Were Soldiers which featured a Sonic Whole Overhead Sound soundtrack. This mix included a new ceiling-mounted height channel . Ambisonics is a recording and playback technique using multichannel mixing that can be used live or in the studio and which recreates the soundfield as it existed in the space, in contrast to traditional surround systems, which can only create illusion of
2760-491: A medium other than air or vacuum, the front and rear focal lengths are equal to the EFL times the refractive index of the medium in front of or behind the lens ( n 1 and n 2 in the diagram above). The term "focal length" by itself is ambiguous in this case. The historical usage was to define the "focal length" as the EFL times the index of refraction of the medium. For a system with different media on both sides, such as
2875-561: A meta-analysis on 20 of the published tests that included sufficient experimental detail and data. In a paper published in the July 2016 issue of the AES Journal, Reiss says that, although the individual tests had mixed results, and that the effect was "small and difficult to detect," the overall result was that trained listeners could distinguish between high-resolution recordings and their CD equivalents under blind conditions: "Overall, there
2990-530: A mixing board specially designed in cooperation with Solid State Logic , based on 5000 series and including six channels. Respectively: A left, B right, C centre, D left rear, E right rear, F bass. The same engineer had already achieved a 3.1 system in 1974, for the International Summit of Francophone States in Dakar , Senegal. Surround sound is created in several ways. The first and simplest method
3105-399: A non-negligible thickness), or an imaging system consisting of several lenses or mirrors (e.g. a photographic lens or a telescope ), there are several related concepts that are referred to as focal lengths: For an optical system in air the effective focal length, front focal length, and rear focal length are all the same and may be called simply "focal length". For an optical system in
3220-473: A significant impact in the marketplace; consumers were increasingly downloading low-resolution music files over the internet rather than buying music on physical disc formats. A small and niche market for SACD has remained, serving the audiophile community. By October 2009, record companies had published more than 6,000 SACD releases, slightly more than half of which were classical music . Jazz and popular music albums, mainly remastered previous releases, were
3335-415: A square, ideally placed far away and high up in the hall. Spacing between the microphones should be between 1–3 meters. The microphones nulls (zero pickup point) are set to face the main sound source with positive polarities outward facing, therefore very effectively minimizing the direct sound pickup as well as echoes from the back of the hall The back two microphones are mixed to the surround channels, with
3450-756: A stereo mix on the standard CD layer. Some popular artists have released new recordings on SACD. Sales figures for Sting 's Sacred Love (2003) album reached number one on SACD sales charts in four European countries in June 2004. Between 2007 and 2008, the rock band Genesis re-released all of their studio albums across three SACD box sets. Each album in these sets contains both new stereo and 5.1 mixes. The original stereo mixes were not included. The US & Canada versions do not use SACD but CD instead. By August 2009 443 labels had released one or more SACDs. Instead of depending on major label support, some orchestras and artists have released SACDs on their own. For instance,
3565-408: A stereo recording to parse out individual sounds to component panorama positions, then positions them, accordingly, into a five-channel field. However, there are more ways to create surround sound out of stereo, for instance with the routines based on QS and SQ for encoding Quad sound, where instruments were divided over 4 speakers in the studio. This way of creating surround with software routines
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3680-477: A subwoofer for the Low Frequency Effects (LFE) channel, that is low-pass filtered at 120 Hz. The angles between the speakers have been standardized by the ITU (International Telecommunication Union) recommendation 775 and AES (Audio Engineering Society) as follows: 60 degrees between the L and R channels (allows for two-channel stereo compatibility) with the center speaker directly in front of
3795-488: A two-dimensional (2-D) sound field with headphones. A third approach, based on Huygens' principle , attempts reconstructing the recorded sound field wave fronts within the listening space; an "audio hologram" form. One form, wave field synthesis (WFS), produces a sound field with an even error field over the entire area. Commercial WFS systems, currently marketed by companies sonic emotion and Iosono , require many loudspeakers and significant computing power. The 4th approach
3910-456: A virtual source, based on level differences between two loudspeakers to the side of a listener, shows great inconsistency across the standardised 5.1 setup, also being largely affected by movement away from the reference position. 5.1 surround is therefore limited in its ability to convey 3D sound, making the surround channels more appropriate for ambience or effects. ) 7.1 channel surround is another setup, most commonly used in large cinemas, that
4025-452: Is a compromise between the ideal image creation of a room and that of practicality and compatibility with two-channel stereo. Because most surround sound mixes are produced for 5.1 surround (6 channels), larger setups require matrixes or processors to feed the additional speakers. The standard surround setup consists of three front speakers LCR (left, center and right), two surround speakers LS and RS (left and right surround respectively) and
4140-515: Is compatible with 5.1 surround, though it is not stated in the ITU-standards. 7.1 channel surround adds two additional channels, center-left (CL) and center-right (CR) to the 5.1 surround setup, with the speakers situated 15 degrees off centre from the listener. This convention is used to cover an increased angle between the front loudspeakers as a product of a larger screen. Most 2-channel stereophonic microphone techniques are compatible with
4255-515: Is currently common). The Apocalypse Now encoder/decoder was designed by Michael Karagosian, also for Dolby Laboratories . The surround mix was produced by an Oscar-winning crew led by Walter Murch for American Zoetrope . The format was also deployed in 1982 with the stereo surround release of Blade Runner . The 5.1 version of surround sound originated in 1987 at the famous French Cabaret Moulin Rouge . A French engineer, Dominique Bertrand used
4370-593: Is defined by the Scarlet Book standard document. Philips and Crest Digital partnered in May 2002 to develop and install the first SACD hybrid disc production line in the United States, with a production capacity of up to three million discs per year. SACD did not achieve the level of growth that compact discs enjoyed in the 1980s, and was not accepted by the mainstream market. By 2007, SACD had failed to make
4485-421: Is determined by numbers encoded in the bit stream. Both modulations require neighboring samples to reconstruct the original waveform; the more neighboring samples, the lower the frequency that can be encoded. DSD is 1-bit , has a sampling rate of 2.8224 MHz , and makes use of noise shaping quantization techniques in order to push 1-bit quantization noise up to inaudible ultrasonic frequencies. This gives
4600-458: Is effective for the pickup of audience and ambience. All the above-mentioned microphone arrays take up considerable space, making them quite ineffective for field recordings. In this respect, the double MS (Mid Side) technique is quite advantageous. This array uses back to back cardioid microphones, one facing forward, the other backwards, combined with either one or two figure-eight microphone. Different channels are obtained by sum and difference of
4715-418: Is negative if the second surface is convex, and positive if concave. Sign conventions vary between different authors, which results in different forms of these equations depending on the convention used. For a spherically-curved mirror in air, the magnitude of the focal length is equal to the radius of curvature of the mirror divided by two. The focal length is positive for a concave mirror, and negative for
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4830-572: Is normally referred to as "upmixing", which was particularly successful on the Sansui QSD-series decoders that had a mode where it mapped the L ↔ R stereo onto an ∩ arc. There are many alternative setups available for a surround sound experience, with a 3-2 (3 front, 2 back speakers and a Low Frequency Effects channel) configuration (more commonly referred to as 5.1 surround) being the standard for most surround sound applications, including cinema, television and consumer applications. This
4945-461: Is often referred to as a wide-angle lens (typically 35 mm and less, for 35 mm-format cameras), while a lens significantly longer than normal may be referred to as a telephoto lens (typically 85 mm and more, for 35 mm-format cameras). Technically, long focal length lenses are only "telephoto" if the focal length is longer than the physical length of the lens, but the term is often used to describe any long focal length lens. Due to
5060-474: Is responsible for the room impressions. The center channel is placed a meter in front of the L and R channels, producing a strong center image. The surround microphones are usually placed at the critical distance (where the direct and reverberant field is equal), with the full array usually situated several meters above and behind the conductor. The NHK (Japanese broadcasting company) developed an alternative technique also involving five cardioid microphones. Here
5175-416: Is the refractive index of the lens medium. The quantity 1 / f is also known as the optical power of the lens. The corresponding front focal distance is: FFD = f ( 1 + ( n − 1 ) d n R 2 ) , {\displaystyle {\mbox{FFD}}=f\left(1+{\frac {(n-1)d}{nR_{2}}}\right),} and
5290-421: Is typical for 2-channel stereo, due to phase differences at the two ears of a listener. The centre channel is especially used in films and television, with dialogue primarily feeding the center channel. The function of the center channel can either be of a monophonic nature (as with dialogue) or it can be used in combination with the left and right channels for true three-channel stereo. Motion Pictures tend to use
5405-452: Is used for the surround channels. The centre channel is again placed slightly forward, with the L/R and LS/RS again angled at 45 and 135 degrees respectively. The OCT-Surround (Optimum Cardioid Triangle-Surround) microphone array is an augmented technique of the stereo OCT technique using the same front array with added surround microphones. The front array is designed for minimum crosstalk, with
5520-431: Is using a surround sound recording technique—capturing two distinct stereo images, one for the front and one for the back or by using a dedicated setup, e.g., an augmented Decca tree —or mixing-in surround sound for playback on an audio system using speakers encircling the listener to play audio from different directions. A second approach is processing the audio with psychoacoustic sound localization methods to simulate
5635-494: Is using three mics, one for front, one for side and one for rear, also called Double MS recording . The Ambisonics form, also based on Huygens' principle , gives an exact sound reconstruction at the central point; however, it is less accurate away from the central point. There are many free and commercial software programs available for Ambisonics, which dominates most of the consumer market, especially musicians using electronic and computer music. Moreover, Ambisonics products are
5750-637: The Chicago Symphony Orchestra started the Chicago Resound label to provide full and burgeoning support for high-resolution SACD hybrid discs, and the London Symphony Orchestra established their own LSO Live label. Many SACD discs that were released from 2000 to 2005 are now out of print and available only on the used market. By 2009, the major record companies were no longer regularly releasing discs in
5865-657: The Decca Tree setup and the OCT (Optimum Cardioid Triangle). Surround techniques are largely based on 3-channel techniques with additional microphones used for the surround channels. A distinguishing factor for the pickup of the front channels in surround is that less reverberation should be picked up, as the surround microphones will be responsible for the pickup of reverberation. Cardioid, hypercardioid, or supercardioid polar patterns will therefore often replace omnidirectional polar patterns for surround recordings. To compensate for
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#17327731253535980-547: The Iannis Xenakis -designed Philips Pavilion at the 1958 Brussels World's Fair , also used spatial audio with 425 loudspeakers used to move sound throughout the pavilion. In 1957, working with artist Jordan Belson , Henry Jacobs produced Vortex: Experiments in Sound and Light - a series of concerts featuring new music, including some of Jacobs' own, and that of Karlheinz Stockhausen , and many others - taking place in
6095-600: The 1950s, the German composer Karlheinz Stockhausen experimented with and produced ground-breaking electronic compositions such as Gesang der Jünglinge and Kontakte , the latter using fully discrete and rotating quadraphonic sounds generated with industrial electronic equipment in Herbert Eimert 's studio at the Westdeutscher Rundfunk (WDR). Edgar Varese 's Poème électronique , created for
6210-431: The 5.1 surround setup, as this is the standard. Surround recording techniques can be differentiated into those that use single arrays of microphones placed in close proximity, and those treating front and rear channels with separate arrays. Close arrays present more accurate phantom images, whereas separate treatment of rear channels is usually used for ambience. For accurate depiction of an acoustic environment, such as
6325-575: The CD layer. Conversely, if a conventional CD is placed into an SACD player, the laser will read the disc as a CD since there is no SACD layer. SACD audio is stored in Direct Stream Digital (DSD) format using pulse-density modulation (PDM) where audio amplitude is determined by the varying proportion of 1s and 0s. This contrasts with compact disc and conventional computer audio systems using pulse-code modulation (PCM) where audio amplitude
6440-459: The CD-quality loop easily. The authors commented: Now, it is very difficult to use negative results to prove the inaudibility of any given phenomenon or process. There is always the remote possibility that a different system or more finely attuned pair of ears would reveal a difference. But we have gathered enough data, using sufficiently varied and capable systems and listeners, to state that
6555-529: The Disney studio's animated film Fantasia . Walt Disney was inspired by Nikolai Rimsky-Korsakov 's operatic piece Flight of the Bumblebee to have a bumblebee featured in his musical Fantasia and also sound as if it was flying in all parts of the theatre. The initial multichannel audio application was called ' Fantasound ', comprising three audio channels and speakers. The sound was diffused throughout
6670-621: The ITU Rec. 775. Dimensions between the front three microphone as well as the polar patterns of the microphones can be changed for different pickup angles and ambient response. This technique therefore allows for great flexibility. A well established microphone array is the Fukada Tree, which is a modified variant of the Decca Tree stereo technique. The array consists of five spaced cardioid microphones, three front microphones resembling
6785-531: The ITU-R BS. 775-1, with 5.1 surround. The 3-1 channel setup (consisting of one monophonic surround channel) is such a case, where both LS and RS are fed by the monophonic signal at an attenuated level of -3 dB. The function of the center channel is to anchor the signal so that any central panned images do not shift when a listener is moving or is sitting away from the sweet spot. The center channel also prevents any timbral modifications from occurring, which
6900-416: The L, R and LS, RS channels. The disadvantage of this approach is that direct sound pickup is quite significant. Many recordings do not require pickup of side reflections. For Live Pop music concerts a more appropriate array for the pickup of ambience is the cardioid trapezium. All four cardioid microphones are backward facing and angled at 60 degrees from one another, therefore similar to a semi-circle. This
7015-406: The LFE channel is not the subwoofer channel ; there may be no subwoofer and, if there is, it may be handling a good deal more than effects. Some record labels such as Telarc and Chesky have argued that LFE channels are not needed in a modern digital multichannel entertainment system. They argue that, given loudspeakers that have low frequency response to 30 Hz, all available channels have
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#17327731253537130-421: The LFE channel. Also, if there is no subwoofer speaker present then the bass management system can direct the LFE channel to one or more of the main speakers. Because the low-frequency effects (LFE) channel requires only a fraction of the bandwidth of the other audio channels, it is referred to as the .1 channel; for example 5.1 or 7.1 . The LFE channel is a source of some confusion in surround sound. It
7245-671: The Morrison Planetarium in Golden Gate Park, San Francisco. Sound designers commonly regard this as the origin of the (now standard) concept of "surround sound." The program was popular, and Jacobs and Belson were invited to reproduce it at the 1958 World Expo in Brussels. There are also many other composers that created ground-breaking surround sound works in the same time period. In 1978, a concept devised by Max Bell for Dolby Laboratories called "split surround"
7360-537: The SACD layer. Some reissues retain the mixes of earlier multi-channel formats (examples include the 1973 quadraphonic mix of Mike Oldfield 's Tubular Bells and the 1957 three-channel stereo recording by the Chicago Symphony Orchestra of Mussorgsky 's Pictures at an Exhibition , reissued on SACD in 2001 and 2004 respectively). Objective lenses in conventional CD players have a longer working distance, or focal length , than lenses designed for SACD players. In SACD-capable DVD, Blu-ray and Ultra HD Blu-ray players,
7475-402: The angle subtended by a large-enough print viewed at a typical viewing distance of the print diagonal, which therefore yields a normal perspective when viewing the print; this angle of view is about 53 degrees diagonally. For full-frame 35 mm-format cameras, the diagonal is 43 mm and a typical "normal" lens has a 50 mm focal length. A lens with a focal length shorter than normal
7590-461: The audio data, with a key encoded on a special area of the disc that is only readable by a licensed SACD device. The HD layer of an SACD disc cannot be played back on computer CD/DVD drives, and SACDs can only be manufactured at the disc replication facilities in Shizuoka and Salzburg . Nonetheless, a PlayStation 3 with an SACD drive and appropriate firmware can use specialized software to extract
7705-429: The back focal distance: BFD = f ( 1 − ( n − 1 ) d n R 1 ) . {\displaystyle {\mbox{BFD}}=f\left(1-{\frac {(n-1)d}{nR_{1}}}\right).} In the sign convention used here, the value of R 1 will be positive if the first lens surface is convex, and negative if it is concave. The value of R 2
7820-650: The burden of proof has now shifted. Further claims that careful 16/44.1 encoding audibly degrades high resolution signals must be supported by properly controlled double-blind tests. Following criticism that the original published results of the study were not sufficiently detailed, the AES published a list of the audio equipment and recordings used during the tests. Since the Meyer–Moran study in 2007, approximately 80 studies have been published on high-resolution audio, about half of which included blind tests. Joshua Reiss performed
7935-399: The center channel for monophonic purposes with stereo being reserved purely for the left and right channels. Surround microphones techniques have however been developed that fully use the potential of three-channel stereo. In 5.1 surround, phantom images between the front speakers are quite accurate, with images towards the back and especially to the sides being unstable. The localisation of
8050-442: The cinema, controlled by an engineer using some 54 loudspeakers. The surround sound was achieved using the sum and the difference of the phase of the sound. However, this experimental use of surround sound was excluded from the film in later showings. In 1952, "surround sound" successfully reappeared with the film "This is Cinerama", using discrete seven-channel sound, and the race to develop other surround sound methods took off. In
8165-550: The content would typically be synthetic noise produced by the computer device in interaction with its user. Significant work has also been done using surround sound for enhanced situation awareness in military and public safety application. Commercial surround sound media include videocassettes , DVDs , and SDTV broadcasts encoded as analog matrixed Dolby Surround compressed Dolby Digital and DTS , and lossless audio such as DTS HD Master Audio and Dolby TrueHD on HDTV Blu-ray Disc and HD DVD , which are identical to
8280-434: The conventional 5.1 arrangement, for a total of four surround channels and three front channels, to create a more 360° sound field. Most surround sound recordings are created by film production companies or video game producers; however some consumer camcorders have such capability either built-in or available separately. Surround sound technologies can also be used in music to enable new methods of artistic expression. After
8395-457: The distance from the front principal plane to the object to photograph s 1 , and the distance from the rear principal plane to the image plane s 2 are then related by: 1 s 1 + 1 s 2 = 1 f . {\displaystyle {\frac {1}{s_{1}}}+{\frac {1}{s_{2}}}={\frac {1}{f}}\,.} As s 1 is decreased, s 2 must be increased. For example, consider
8510-816: The eye, or it can be represented by a different equivalent thin lens that is totally in air, with focal length equal to the eye's EFL. For the case of a lens of thickness d in air ( n 1 = n 2 = 1 ), and surfaces with radii of curvature R 1 and R 2 , the effective focal length f is given by the Lensmaker's equation : 1 f = ( n − 1 ) ( 1 R 1 − 1 R 2 + ( n − 1 ) d n R 1 R 2 ) , {\displaystyle {\frac {1}{f}}=(n-1)\left({\frac {1}{R_{1}}}-{\frac {1}{R_{2}}}+{\frac {(n-1)d}{nR_{1}R_{2}}}\right),} where n
8625-420: The failure of quadraphonic audio in the 1970s, multichannel music has slowly been reintroduced since 1999 with the help of SACD and DVD-Audio formats. Some AV receivers , stereophonic systems, and computer sound cards contain integral digital signal processors or digital audio processors to simulate surround sound from a stereophonic source (see fake stereo ). In 1967, the rock group Pink Floyd performed
8740-510: The figure-eight and cardioid patterns. When using only one figure-eight microphone, the double MS technique is extremely compact and therefore also perfectly compatible with monophonic playback. This technique also allows for postproduction changes of the pickup angle. Surround replay systems may make use of bass management , the fundamental principle of which is that bass content in the incoming signal, irrespective of channel, should be directed only to loudspeakers capable of handling it, whether
8855-440: The film plane, to s 2 = 52.6 mm. The focal length of a lens determines the magnification at which it images distant objects. It is equal to the distance between the image plane and a pinhole that images distant objects the same size as the lens in question. For rectilinear lenses (that is, with no image distortion ), the imaging of distant objects is well modelled as a pinhole camera model . This model leads to
8970-482: The first-ever surround sound concert at "Games for May", a lavish affair at London ’s Queen Elizabeth Hall where the band debuted its custom-made quadraphonic speaker system. The control device they had made, the Azimuth Co-ordinator , is now displayed at London's Victoria and Albert Museum , as part of their Theatre Collections gallery. The first documented use of surround sound was in 1940, for
9085-434: The focal length f are related by The focal length of a thin convex lens can be easily measured by using it to form an image of a distant light source on a screen. The lens is moved until a sharp image is formed on the screen. In this case 1 / u is negligible, and the focal length is then given by Determining the focal length of a concave lens is somewhat more difficult. The focal length of such
9200-633: The format a greater dynamic range and wider frequency response than the CD. The SACD format is capable of delivering a dynamic range of 120 dB from 20 Hz to 20 kHz and an extended frequency response up to 100 kHz, although most available players list an upper limit of 70–90 kHz, and practical limits reduce this to 50 kHz. Because of the nature of sigma-delta converters , DSD and PCM cannot be directly compared. DSD's frequency response can be as high as 100 kHz, but frequencies that high compete with high levels of ultrasonic quantization noise . With appropriate low-pass filtering ,
9315-486: The format, with new releases confined to the smaller labels. SACD discs have identical physical dimensions as standard compact discs. The areal density of the disc is the same as a DVD . There are three types of disc: A stereo SACD recording has an uncompressed rate of 5.6 Mbit/s , four times the rate for Red Book CD stereo audio. Commercial releases commonly include both surround sound (five full-range plus LFE multi-channel) and stereo (dual-channel) mixes on
9430-410: The front array. If echoes are notable, the front array can be delayed appropriately. Alternatively, backward facing cardioid microphones can be placed closer to the front array for a similar reverberation pickup. The INA-5 (Ideal Cardioid Arrangement) is a surround microphone array that uses five cardioid microphones resembling the angles of the standardised surround loudspeaker configuration defined by
9545-401: The front left and right microphones having supercardioid polar patterns and angled at 90 degrees relative to the center microphone. It is important that high quality small diaphragm microphones are used for the L and R channels to reduce off-axis coloration. Equalization can also be used to flatten the response of the supercardioid microphones to signals coming in at up to about 30 degrees from
9660-426: The front of the array. The center channel is placed slightly forward. The surround microphones are backwards facing cardioid microphones, that are placed 40 cm back from the L and R microphones. The L, R, LS and RS microphones pick up early reflections from both the sides and the back of an acoustic venue, therefore giving significant room impressions. Spacing between the L and R microphones can be varied to obtain
9775-544: The front two channels being mixed in combination with the front array into L and R. Another ambient technique is the IRT (Institut für Rundfunktechnik) cross. Here, four cardioid microphones, 90 degrees relative to one another, are placed in square formation, separated by 21–25 cm. The front two microphones should be positioned 45 degrees off axis from the sound source. This technique therefore resembles back to back near-coincident stereo pairs. The microphones outputs are fed to
9890-491: The human eye, the front and rear focal lengths are not equal to one another, and convention may dictate which one is called "the focal length" of the system. Some modern authors avoid this ambiguity by instead defining "focal length" to be a synonym for EFL. The distinction between front/rear focal length and EFL is important for studying the human eye. The eye can be represented by an equivalent thin lens at an air/fluid boundary with front and rear focal lengths equal to those of
10005-408: The intent to create the 3-D stereo experience of being present in the room with the performers or instruments. The idea of a three dimensional or "internal" form of sound has developed into technology for stethoscopes creating "in-head" acoustics and IMAX movies creating a three dimensional acoustic experience. Focal length The focal length of an optical system is a measure of how strongly
10120-538: The latter are the main system loudspeakers or one or more special low-frequency speakers called subwoofers . There is a notation difference before and after the bass management system. Before the bass management system there is a Low Frequency Effects (LFE) channel. After the bass management system there is a subwoofer signal. A common misunderstanding is the belief that the LFE channel is the "subwoofer channel". The bass management system may direct bass to one or more subwoofers (if present) from any channel, not just from
10235-411: The lens, a shorter focal length (higher optical power) leads to higher magnification because the subject can be brought closer to the center of projection. For a thin lens in air, the focal length is the distance from the center of the lens to the principal foci (or focal points ) of the lens. For a converging lens (for example a convex lens ), the focal length is positive and is the distance at which
10350-478: The listener ( surround channels ). Its first application was in movie theaters . Prior to surround sound, theater sound systems commonly had three screen channels of sound that played from three loudspeakers (left, center, and right) located in front of the audience. Surround sound adds one or more channels from loudspeakers to the side or behind the listener that are able to create the sensation of sound coming from any horizontal direction (at ground level) around
10465-427: The listener. The technique enhances the perception of sound spatialization by exploiting sound localization : a listener's ability to identify the location or origin of a detected sound in direction and distance. This is achieved by using multiple discrete audio channels routed to an array of loudspeakers . Surround sound typically has a listener location ( sweet spot ) where the audio effects work best and presents
10580-435: The listener. The Surround channels are placed 100–120 degrees from the center channel, with the subwoofer's positioning not being critical due to the low directional factor of frequencies below 120 Hz. The ITU standard also allows for additional surround speakers, that need to be distributed evenly between 60 and 150 degrees. Surround mixes of more or fewer channels are acceptable, if they are compatible, as described by
10695-412: The lost low-end of directional (pressure gradient) microphones, additional omnidirectional (pressure microphones), exhibiting an extended low-end response, can be added. The microphone's output is usually low-pass filtered. A simple surround microphone configuration involves the use of a front array in combination with two backward-facing omnidirectional room microphones placed about 10–15 meters away from
10810-544: The next two genres most represented. Many popular artists have released some or all of their back catalog on SACD. Pink Floyd 's album The Dark Side of the Moon (1973) sold over 800,000 copies by June 2004 in its SACD Surround Sound edition. The Who 's rock opera Tommy (1969), and Roxy Music 's Avalon (1982), were released on SACD to take advantage of the format's multi-channel capability. All three albums were remixed in 5.1 surround , and released as hybrid SACDs with
10925-429: The number of full-range channels in front of the listener, separated by a slash from the number of full-range channels beside or behind the listener, with a decimal point marking the number of limited-range LFE channels. E.g. 3 front channels + 2 side channels + an LFE channel = 3/2.1 The notation can be expanded to include Matrix Decoders . Dolby Digital EX, for example, has a sixth full-range channel incorporated into
11040-441: The number of speakers used to reproduce them if one or more channels drives a group of speakers. Notation represents the number of channels, not the number of speakers. The first digit in "5.1" is the number of full range channels. The ".1" reflects the limited frequency range of the LFE channel. For example, two stereo speakers with no LFE channel = 2.0 5 full-range channels + 1 LFE channel = 5.1 An alternative notation shows
11155-404: The original movie theater implementation, the LFE was a separate channel fed to one or more subwoofers. Home replay systems, however, may not have a separate subwoofer, so modern home surround decoders and systems often include a bass management system that allows bass on any channel (main or LFE) to be fed only to the loudspeakers that can handle low-frequency signals. The salient point here is that
11270-490: The popularity of the 35 mm standard , camera–lens combinations are often described in terms of their 35 mm-equivalent focal length, that is, the focal length of a lens that would have the same angle of view, or field of view, if used on a full-frame 35 mm camera. Use of a 35 mm-equivalent focal length is particularly common with digital cameras , which often use sensors smaller than 35 mm film, and so require correspondingly shorter focal lengths to achieve
11385-422: The red DVD laser is used for reading SACDs. This means that when a hybrid SACD is placed into a conventional CD player, the infrared laser beam passes through the SACD layer and is reflected by the CD layer at the standard 1.2 mm distance, and the SACD layer is out of focus. When the same disc is placed into an SACD player, the red laser is reflected by the SACD layer (at 0.6 mm distance) before it can reach
11500-413: The required stereo width. Specialized microphone arrays have been developed for recording purely the ambience of a space. These arrays are used in combination with suitable front arrays, or can be added to above mentioned surround techniques. The Hamasaki square (also proposed by NHK) is a well established microphone array used for the pickup of hall ambience. Four figure-eight microphones are arranged in
11615-407: The sensor or film, which is then situated at the focal plane , by the lens's focal length. Objects far away from the camera then produce sharp images on the sensor or film, which is also at the image plane. To render closer objects in sharp focus, the lens must be adjusted to increase the distance between the rear principal plane and the film, to put the film at the image plane. The focal length f ,
11730-402: The simple geometric model that photographers use for computing the angle of view of a camera; in this case, the angle of view depends only on the ratio of focal length to film size . In general, the angle of view depends also on the distortion. A lens with a focal length about equal to the diagonal size of the film or sensor format is known as a normal lens ; its angle of view is similar to
11845-445: The soundfield if the listener is located in a very narrow sweetspot between speakers. Any number of speakers in any physical arrangement can be used to recreate a sound field. With 6 or more speakers arranged around a listener, a 3-dimensional ("periphonic", or full-sphere) sound field can be presented. Ambisonics was invented by Michael Gerzon . Binaural recording is a method of recording sound that uses two microphones, arranged with
11960-495: The speech of the characters of a film, but may also be applied to plays performed in a theatre, to a conference, or to integrate voice-based comments in an archeological site or monument. For example, an exhibition may be enhanced with topical ambient sound of water, birds, train or machine noise. Topical natural sounds may also be used in educational applications. Other fields of application include video game consoles, personal computers and other platforms. In such applications,
12075-469: The standard in surround sound hardware sold by Meridian Audio . In its simplest form, Ambisonics consumes few resources, however this is not true for recent developments, such as Near Field Compensated Higher Order Ambisonics. Some years ago it was shown that, in the limit, WFS and Ambisonics converge. Finally, surround sound can also be achieved by mastering level, from stereophonic sources as with Penteo , which uses digital signal processing analysis of
12190-513: The studio master. Other commercial formats include the competing DVD-Audio (DVD-A) and Super Audio CD (SACD) formats, and MP3 Surround . Cinema 5.1 surround formats include Dolby Digital and DTS . Sony Dynamic Digital Sound (SDDS) is an 8 channel cinema configuration which features 5 independent audio channels across the front with two independent surround channels, and a Low-frequency effects channel. Traditional 7.1 surround speaker configuration introduces two additional rear speakers to
12305-399: The subject is essentially infinitely far away, longer focal length (lower optical power) leads to higher magnification and a narrower angle of view ; conversely, shorter focal length or higher optical power is associated with lower magnification and a wider angle of view. On the other hand, in applications such as microscopy in which magnification is achieved by bringing the object close to
12420-406: The system converges or diverges light ; it is the inverse of the system's optical power . A positive focal length indicates that a system converges light, while a negative focal length indicates that the system diverges light. A system with a shorter focal length bends the rays more sharply, bringing them to a focus in a shorter distance or diverging them more quickly. For the special case of
12535-509: The third generation (introduced October 2007), SACD playback was removed. All PlayStation 3 models, however, will play DSD Disc format. The PlayStation 3 was capable of converting multi-channel DSD to lossy 1.5 Mbit/s DTS for playback over S/PDIF using the 2.00 system software . The subsequent revision removed the feature. Several brands have introduced (mostly high-end ) Blu-ray Disc and Ultra HD Blu-ray players that can play SACD discs. Unofficial playback of SACD disc images on
12650-521: The two rear channels with a matrix . This is expressed: 3 front channels + 2 rear channels + 3 channels reproduced in the rear in total + 1 LFE channel = 3/2:3.1 The term stereo , although popularised in reference to two channel audio, historically also referred to surround sound, as it strictly means "solid" (three-dimensional) sound. However this is no longer common usage and "stereo sound" almost exclusively means two channels, left and right. In accordance with ANSI/CEA-863-A In 2002, Dolby premiered
12765-625: Was "only slightly better than chance." Contradictory results have been found when comparing DSD and high-resolution PCM formats. Double-blind listening tests in 2004 between DSD and 24-bit, 176.4 kHz PCM recordings reported that among test subjects no significant differences could be heard. DSD advocates and equipment manufacturers continue to assert an improvement in sound quality above PCM 24-bit 176.4 kHz. A 2003 study found that despite both formats' extended frequency responses, people could not distinguish audio with information above 21 kHz from audio without such high-frequency content. In
12880-454: Was a small but statistically significant ability to discriminate between standard-quality audio (44.1 or 48 kHz, 16 bit) and high-resolution audio (beyond standard quality). When subjects were trained, the ability to discriminate was far more significant." Hiroshi Nittono pointed out that the results in Reiss's paper showed that the ability to distinguish high-resolution audio from CD-quality audio
12995-440: Was originally developed to carry extremely low sub-bass cinematic sound effects (e.g., the loud rumble of thunder or explosions) on their own channel. This allowed theaters to control the volume of these effects to suit the particular cinema's acoustic environment and sound reproduction system. Independent control of the sub-bass effects also reduced the problem of intermodulation distortion in analog movie sound reproduction. In
13110-524: Was published as ISO/IEC 14496-5:2001/Amd.10:2007 in 2007. SACD has several copy protection features at the physical level, which made the digital content of SACD discs difficult to copy until the jailbreak of the PlayStation 3 . The content may be copyable without SACD quality by resorting to the analog hole , or ripping the conventional 700 MB layer on hybrid discs. Copy protection schemes include physical pit modulation and 80-bit encryption of
13225-490: Was tested with the movie Superman . This led to the 70mm stereo surround release of Apocalypse Now , which became one of the first formal releases in cinemas with three channels in the front and two in the rear. There were typically five speakers behind the screens of 70mm-capable cinemas, but only the Left, Center and Right were used full-frequency, while Center-Left and Center-Right were only used for bass-frequencies (as it
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