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49-622: Moving Picture Experts Group (MPEG) issued a call for proposals on MPEG Spatial Audio Coding in March 2004. The group decided that the technology that would be the starting point in standardization process, would be a combination of the submissions from two proponents - Fraunhofer IIS / Agere Systems and Coding Technologies / Philips. The MPEG Surround standard was developed by the Moving Picture Experts Group ( ISO/IEC JTC 1 /SC29/WG11) and published as ISO/IEC 23003 in 2007. It

98-489: A band-pass filter (cutting frequencies under 100 Hz and above 7 kHz), passes through Dolby B noise reduction and is encoded on the left and right channels with opposite polarity (this is achieved by applying a +90-degree phase shift to the left channel and a −90-degree phase shift to the right channel). The surround channel was often used for ambient background sounds in the original recording, music scores and effects. A Dolby Pro Logic decoder/processor "unfolds"

147-458: A consensus is reached to proceed to the next stage, the draft becomes a Draft International Standard (DIS) and is sent for another ballot. After a review and comments issued by NBs and a resolution of comments in the working group, a Final Draft International Standard (FDIS) is typically issued for a final approval ballot. The final approval ballot is voted on by National Bodies, with no technical changes allowed (a yes/no approval ballot). If approved,

196-1021: A faithful equivalent of the multichannel signal in the mono or stereo downmix, but also creates the best possible multichannel decoding based on the downmix and encoded spatial cues as well. Alternatively, the downmix could be supplied externally (Artistic Downmix in before Diagram Block). The MPEG Surround encoding process could be ignored by the compression algorithm used for the transmitted channels (Audio Encoder and Audio Decoder in before Diagram Block). It could be any type of high-performance compression algorithms such as MPEG-1 Layer III, MPEG-4 AAC or MPEG-4 High Efficiency AAC, or it could even be PCM. The spatial signals are generated and recovered in two types of filter modules. The reverse-OTT (one-to-two) generates one downmixed stream, one level difference, one coherence value, and an optional residue signal from one pair of signals. The reverse-TTT (two-to-three) element generates two downmixed streams, two level differences, one coherence value, and an optional residue signal. In both

245-620: A mode designed specifically for video games which is used in games for PlayStation 2 , GameCube , and Wii as an alternative to digital surround formats such as Dolby Digital or DTS . Game mode is similar to Movie mode, except it redirects more bass to the LFE channel. The Dolby Pro Logic IIx system, available since 2003, can take two-channel stereo, Dolby Surround (sometimes called Dolby Stereo Surround) and Dolby Digital 5.1 source material and up-convert it to 6.1 or 7.1 channel surround sound . Dolby Pro Logic IIz expands on Pro Logic IIx with

294-569: A restructuring process within SC 29 , in which "some of the subgroups of WG 11 (MPEG) [became] distinct MPEG working groups (WGs) and advisory groups (AGs)" in July 2020. Prof. Jörn Ostermann of University of Hannover was appointed as Acting Convenor of SC 29/WG 11 during the restructuring period and was then appointed Convenor of SC 29's Advisory Group 2, which coordinates MPEG overall technical activities. The MPEG structure that replaced

343-506: A result, offers an exceptionally stable sound field that simulates five-channel surround sound. Because of the limited nature of the original Dolby Pro Logic encoding, many consumer electronics manufacturers introduced their own processing circuitry, such as the "Jazz", "Hall", and "Stadium" modes found on most common home audio receivers. DPL II forgoes this type of processing and replaces it with simple servo ( negative feedback ) circuits used to derive five channels. The extra channel content

392-475: A set of tools that are available, and Levels define the range of appropriate values for the properties associated with them. Some of the approved MPEG standards were revised by later amendments and/or new editions. The primary early MPEG compression formats and related standards include: MPEG-4 AVC was chosen as the video compression scheme for over-the-air television broadcasting in Brazil (ISDB-TB), based on

441-467: Is a surround sound processing technology developed by Dolby Laboratories , designed to decode soundtracks encoded with Dolby Surround . The terms Dolby Stereo and LtRt ( Left Total , Right Total ) are also used to describe soundtracks that are encoded using this technique. Dolby Stereo —also known as Dolby MP ( Motion Picture ) or Dolby SVA ( stereo variable-area )—was developed by Dolby in 1976 for analog cinema sound systems. The format

490-402: Is a joint group of video coding experts from ITU-T Study Group 16 (VCEG) and ISO/IEC JTC 1/SC 29/WG 11 (MPEG) created in 2017, which was later audited by ATR-M audio group, after an exploration phase that began in 2015. JVET developed Versatile Video Coding (VVC, MPEG-I Part 3, ITU-T H.266), completed in July 2020, which further reduces the data rate for video coding by about 50%, as compared to

539-443: Is desirable since stereo presentation will remain pervasive due to the number of applications in which listening is primarily via headphones, such as portable music players. MPEG Surround also supports a mode in which the downmix is compatible with popular matrix surround decoders, such as Dolby Pro-Logic . Due to the relatively small channel bandwidth, the relatively large cost of transmission equipment and transmission licenses and

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588-424: Is extracted using the difference between the spatial audio content between two individual channels of stereo tracks or Dolby Digital encoded 5.1 channel tracks and outputs it appropriately. In addition to five full-range playback channels, Pro Logic II introduced a Music mode that includes optimized channel delays and adds user controls to—for example—adjust apparent sound stage width. Pro Logic II systems also have

637-640: Is of paramount importance in this application, compression of the transmitted audio signal is vital. Using recent MPEG compression technology (MPEG-4 High Efficiency Profile coding), full MPEG Surround systems have been demonstrated with bitrates as low as 48 kbit/s. Moving Picture Experts Group The Moving Picture Experts Group ( MPEG ) is an alliance of working groups established jointly by ISO and IEC that sets standards for media coding, including compression coding of audio , video , graphics, and genomic data; and transmission and file formats for various applications. Together with JPEG , MPEG

686-426: Is organized under ISO/IEC JTC 1 / SC 29 – Coding of audio, picture, multimedia and hypermedia information (ISO/IEC Joint Technical Committee 1, Subcommittee 29). MPEG formats are used in various multimedia systems. The most well known older MPEG media formats typically use MPEG-1 , MPEG-2 , and MPEG-4 AVC media coding and MPEG-2 systems transport streams and program streams . Newer systems typically use

735-426: Is produced for audio and video coding standards is typically called a test model. When a sufficient confidence in the stability of the standard under development is reached, a Working Draft (WD) is produced. When a WD is sufficiently solid (typically after producing several numbered WDs), the next draft is issued as a Committee Draft (CD) (usually at the planned time) and is sent to National Bodies (NBs) for comment. When

784-423: Is the full name that refers to the matrix surround format and decoding system in one. When a Dolby Surround soundtrack is created in post-production ( Dolby MP Matrix ), four channels of sound are matrix-encoded into an ordinary stereo (two-channel) soundtrack. The center channel is reduced in level by 3 dB and summed to the left and right channels; the surround channel is attenuated by 3 dB, passes through

833-620: Is the last stage of an approval process that starts with the proposal of new work within a committee. Stages of the standard development process include: Other abbreviations: A proposal of work (New Proposal) is approved at the Subcommittee level and then at the Technical Committee level (SC 29 and JTC 1, respectively, in the case of MPEG). When the scope of new work is sufficiently clarified, MPEG usually makes open "calls for proposals". The first document that

882-412: Is unaffected by the operation of the channel steering. Additionally, the response time of the system to changes in sound direction is important as too fast a response results in a twitchy feel, while too slow a response leaves sounds coming from an inappropriate direction. In addition to 5 dB of noise reduction, the surround channel is slightly delayed, so that any front channel sounds that leak into

931-541: The MPEG-2 Video standard (ISO/IEC 13818-2) as ITU-T H.262. Sakae Okubo (NTT), was the ITU-T coordinator and chaired the agreements on its requirements. Joint Video Team (JVT) was joint project between ITU-T SG16 /Q.6 (Study Group 16 / Question 6) – VCEG (Video Coding Experts Group) and ISO/IEC JTC 1/SC 29/WG 11 – MPEG for the development of a video coding ITU-T Recommendation and ISO/IEC International Standard. It

980-579: The Dolby Stereo theater processor with active steering logic and much better channel separation (up to 30 dB) as well as including a dedicated center channel output for the first time. Many standalone Pro Logic decoders also included a phantom center option for compatibility with earlier non-Pro Logic Dolby Surround equipped home theaters to split the center channel signal to the L/R speakers for legacy phantom center reproduction. Dolby Surround Pro Logic

1029-450: The ILD, ITD and IC parameters. The spatial image is captured by a multichannel audio signal relative to a transmitted downmix signal. These parameters are encoded in a very compact form so as to decode the parameters and the transmitted signal and to synthesize a high quality multichannel representation. [REDACTED] MPEG Surround encoder receives a multichannel audio signal x1 to xN where

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1078-607: The MPEG base media file format and dynamic streaming (a.k.a. MPEG-DASH ). MPEG was established in 1988 by the initiative of Dr. Hiroshi Yasuda ( NTT ) and Dr. Leonardo Chiariglione ( CSELT ). Chiariglione was the group's chair (called Convenor in ISO/IEC terminology) from its inception until June 6, 2020. The first MPEG meeting was in May 1988 in Ottawa, Canada . Starting around

1127-431: The addition of a height component, creating front height channels above the front left and right speakers, expanding a 5.1 or 7.1 system to 7.1 Height or 9.1. It identifies spatial cues in low-level, uncorrelated information, such as ambience and effects like rain or wind in the side and rear surround channels, and directs it to the front height speakers. The channels it adds are matrixed, not discrete. Dolby reintroduced

1176-512: The center channel could leak into the surround channel—there was as little as 3 dB of separation between LCR and Surround channels. In 1987 the decoding technology was updated and renamed Dolby Pro Logic . A Pro Logic decoder/processor "unfolds" the sound into the original 4.0 surround—left and right, center , and a single limited frequency-range (7 kHz low-pass filtered ) mono rear channel. A Pro Logic decoder also uses 'Steering Logic', which drives amplifiers to raise or lower

1225-427: The compressed sound files are presented in surround sound while on portable players the same files are reproduced in stereo. Many Internet radios operate with severely constrained transmission bandwidth, such that they can offer only mono or stereo content. MPEG Surround Coding technology could extend this to a multichannel service while still remaining within the permissible operating range of bitrates. Since efficiency

1274-461: The consumer passive matrix decoding technology; the professional, active-matrix cinema technology bore the name Dolby Stereo . It was capable of decoding Dolby Stereo four-channel soundtracks to three output channels (Left, Right, Surround). The Center channel was fed equally to the Left and Right speakers. The Surround channel was limited to a 100 Hz to 7 kHz frequency bandwidth, as dialog from

1323-477: The core codec. MPEG Surround coding uses our capacity to perceive sound in the 3D and captures that perception in a compact set of parameters. Spatial perception is primarily attributed to three parameters, or cues, describing how humans localize sound in the horizontal plane: Interaural level difference (ILD), Interaural time difference (ITD) and Interaural coherence (IC). This three concepts are illustrated in next image. Direct, or first-arrival, waveforms from

1372-737: The decoding side to interactively control the rendering of each individual audio object (e.g. individual instruments, vocals, human voices). There is also the Unified Speech and Audio Coding (USAC) which will be defined in MPEG-D Part 3 - ISO/IEC 23003-3 and ISO/IEC 14496-3:2009/Amd 3. MPEG-D MPEG Surround parametric coding tools are integrated into the USAC codec. The (mono or stereo) core could be coded with any ( lossy or lossless ) audio codec . Particularly low bitrates (64-96 kbit/s for 5.1 channels) are possible when using HE-AAC v2 as

1421-507: The desire to maximize user choices by providing many programs, the majority of existing or planned digital broadcasting systems cannot provide multichannel sound to the users. DRM+ was designed to be fully capable of transmitting MPEG Surround and such broadcasting was also successfully demonstrated. MPEG Surround's backward compatibility and relatively low overhead provides one way to add multichannel sound to DAB without severely reducing audio quality or impacting other services. Currently,

1470-438: The digital television system of Japan (ISDB-T). An MPEG-3 project was cancelled. MPEG-3 was planned to deal with standardizing scalable and multi-resolution compression and was intended for HDTV compression, but was found to be unnecessary and was merged with MPEG-2; as a result there is no MPEG-3 standard. The cancelled MPEG-3 project is not to be confused with MP3 , which is MPEG-1 or MPEG-2 Audio Layer III. In addition,

1519-520: The document becomes an International Standard (IS). In cases where the text is considered sufficiently mature, the WD, CD, and/or FDIS stages can be skipped. The development of a standard is completed when the FDIS document has been issued, with the FDIS stage only being for final approval, and in practice, the FDIS stage for MPEG standards has always resulted in approval. Dolby Pro-Logic Dolby Pro Logic

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1568-609: The first was the MSP400 surround sound receiver and amplifier by RCA for their high-end Dimensia brand. It was released in 1987 for the Digital Command Component System . Dolby Surround is the earliest consumer version of Dolby's surround sound decoding technology. It was introduced to the public in 1982 during the time home video recording formats (such as Betamax and VHS ) were introducing Stereo and HiFi capability. The name Dolby Surround described

1617-479: The following standards, while not sequential advances to the video encoding standard as with MPEG-1 through MPEG-4, are referred to by similar notation: Moreover, more recently than other standards above, MPEG has produced the following international standards; each of the standards holds multiple MPEG technologies for a variety of applications. (For example, MPEG-A includes a number of technologies on multimedia application format.) A standard published by ISO/IEC

1666-576: The former Working Group 11 includes three Advisory Groups (AGs) and seven Working Groups (WGs) The first meeting under the current structure was held in August 2024, with MPEG 147 MPEG-2 development included a joint project between MPEG and ITU-T Study Group 15 (which later became ITU-T SG16), resulting in publication of the MPEG-2 Systems standard (ISO/IEC 13818-1, including its transport streams and program streams ) as ITU-T H.222.0 and

1715-421: The forward (decoding) and reverse (encoding) directions, arranging these filters into a tree setup allows for arbitrary downmixing and recovery. The MPEG Surround technique allows for compatibility with existing and future stereo MPEG decoders by having the transmitted downmix (e.g. stereo) appear to stereo MPEG decoders to be an ordinary stereo version of the multichannel signal. Compatibility with stereo decoders

1764-459: The majority of digital TV broadcasts use stereo audio coding. MPEG Surround could be used to extend these established services to surround sound, as with DAB. Currently, a number of commercial music download services are available and working with considerable commercial success. Such services could be seamlessly extended to provide multichannel presentations while remaining compatible with stereo players: on computers with 5.1 channel playback systems

1813-425: The number of input channels is N . The most important aspect of the encoding process is that a downmix signal, xt1 and xt2, which is typically stereo, is derived from the multichannel input signal, and it is this downmix signal that is compressed for transmission over the channel rather than the multichannel signal. The encoder may be able to exploit the downmix process so as to be more advantageous. It not only creates

1862-449: The output volume of each channel based on the current dominant sound direction. For example, while a mono signal is played, the strong correlation to the center channel triggers the output volume of the left, right and surround channels to be lowered. This increases the channel separation achievable to around 30 decibels between channels. By careful tuning of the response of the amplifiers, the total amount of signal energy remains constant and

1911-479: The soundtrack back into its original 4.0 surround—left and right, center , and a single limited frequency-range (7 kHz low-pass filtered ) mono rear channel—while systems lacking the decoder play back the audio as standard stereo. Although Dolby Surround was introduced as an analog format, all Dolby Digital decoders incorporate a digitally implemented Dolby Surround Pro Logic decoder for digital stereo signals that carry matrix-encoded Dolby Surround. One of

1960-571: The source hit the left ear at time, while direct sound received by the right ear is diffracted around the head, with time delay and level attenuation, associated. These two effects result in ITD and ILD are associated with the main source. At last, in a reverberant environment, reflected sound from the source, or sound from diffuse source, or uncorrelated sound can hit both ears, all of them are related with IC. [REDACTED] MPEG Surround uses interchannel differences in level, phase and coherence equivalent to

2009-1092: The surround channel arrive at the listener after the front channels. This takes advantage of the Haas effect —audio that is present in the front speakers but delayed in the surround speakers will have the psychoacoustic effect of emanating from the front of the sound stage. Dolby Surround and Dolby Pro Logic decoders are similar in principle, as both use matrix technology to extract extra channels from Dolby Stereo stereo-encoded audio. The terms Dolby Stereo, Dolby Surround and Lt/Rt are all used to describe soundtracks that are matrix-encoded using this technique. In 2000, Dolby introduced Dolby Pro Logic II (DPL II), an improved implementation of Dolby Pro Logic created by Jim Fosgate . DPL II processes any high-quality stereo signal source into five separate full frequency channels (right front, center, left front, right rear and left rear), while also decoding five channels from stereo signals encoded in traditional four-channel Dolby Surround. DPL II implements greatly enhanced steering compared to DPL, and as

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2058-519: The then-current ITU-T H.265 / HEVC standard, and the JCT-VC was merged into JVET in July 2020. Like JCT-VC, JVET was co-chaired by Jens-Rainer Ohm and Gary Sullivan, until July 2021 when Ohm became the sole chair (after Sullivan became the chair of SC 29). The MPEG standards consist of different Parts . Each Part covers a certain aspect of the whole specification. The standards also specify profiles and levels . Profiles are intended to define

2107-574: The time of the MPEG-4 project in the late 1990s and continuing to the present, MPEG had grown to include approximately 300–500 members per meeting from various industries, universities, and research institutions. On June 6, 2020, the MPEG section of Chiariglione's personal website was updated to inform readers that he had retired as Convenor, and he said that the MPEG group (then SC 29/WG 11) "was closed". Chiariglione described his reasons for stepping down in his personal blog. His decision followed

2156-483: Was a group of video coding experts from ITU-T Study Group 16 (VCEG) and ISO/IEC JTC 1/SC 29/WG 11 (MPEG). It was created in 2010 to develop High Efficiency Video Coding (HEVC, MPEG-H Part 2, ITU-T H.265), a video coding standard that further reduces by about 50% the data rate required for video coding, as compared to the then-current ITU-T H.264 / ISO/IEC 14496-10 standard. JCT-VC was co-chaired by Prof. Jens-Rainer Ohm and Gary Sullivan. Joint Video Experts Team (JVET)

2205-586: Was adapted for home use in 1982 as Dolby Surround when HiFi capable consumer VCRs were introduced. It was further improved with the Dolby Pro Logic decoding system after 1987. The Dolby MP Matrix was the professional system that encoded four channels of film sound into two. This track used by the Dolby Stereo theater system on a 35mm optical stereo print and decoded back to the original 4.0 Surround. The same four-channel encoded stereo track

2254-528: Was equally split between the left and right channels for phantom center reproduction. This differed from the Cinema Dolby Stereo system which used active steering and other processing to decode a center channel for dialog and center focused on-screen action. Later on in 1987, the Pro Logic decoding system was released to consumers. It featured virtually the same type of four-channel decoding as

2303-631: Was formed in 2001 and its main result was H.264/MPEG-4 AVC (MPEG-4 Part 10), which reduces the data rate for video coding by about 50%, as compared to the then-current ITU-T H.262 / MPEG-2 standard. The JVT was chaired by Dr. Gary Sullivan, with vice-chairs Dr. Thomas Wiegand of the Heinrich Hertz Institute in Germany and Dr. Ajay Luthra of Motorola in the United States. Joint Collaborative Team on Video Coding (JCT-VC)

2352-461: Was largely left unchanged and made available to consumers as "Dolby Surround" on home video. However, the original Dolby Surround decoders in 1982 were a simple passive matrix three-channel decoder: L/R and mono Surround . The surround channel was limited to 7 kHz. It also had Dolby Noise Reduction and an adjustable delay, for improved channel separation and to prevent dialog leaking and arriving to listeners' ears first. The front center channel

2401-739: Was the first standard of MPEG-D standards group, formally known as ISO/IEC 23003 - MPEG audio technologies . MPEG Surround was also defined as one of the MPEG-4 Audio Object Types in 2007. There is also the MPEG-4 No Delay MPEG Surround object type (LD MPEG Surround), which was published in 2010. The Spatial Audio Object Coding (SAOC) was published as MPEG-D Part 2 - ISO/IEC 23003–2 in 2010 and it extends MPEG Surround standard by re-using its spatial rendering capabilities while retaining full compatibility with existing receivers. MPEG SAOC system allows users on

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