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(AC-3, ATSC A/52) (Dolby Digital) is a surround sound system developed by Dolby Laboratories, Inc. ("Dolby Labs"), led by Ray Dolby, a pioneer in the audio and video industry.

The format is standardized by the Advanced Television Systems Committee and assigned the code A/52, Dolby Digital (DD) is a trademark.

Modern Dolby Digital systems provide six channels of digital surround sound. Left, center and right front channels allow you to accurately determine the position of the sound source on the screen. Separate "split" left and right rear side channels enhance the sense of presence by creating volume. And an additional low-frequency channel adds heat to the action on the screen.

In the film industry, the Dolby Digital soundtrack is optically encoded directly onto the film in the gaps between the perforations. Placing the digital soundtrack on the same medium as the film allows it to co-exist with the analog track without the need for additional storage media, and ensures absolute synchronization of picture and sound.

Dolby Digital surround sound system supports 6 channels:

• front left and right
• front center
• rear left and right
• subwoofer

Thus, in total, Dolby Digital is suitable for 5.1 surround sound reproduction.

Data compression

One two-hour movie requires about four gigabytes for the audio track alone, if the audio data is not compressed. A dual-layer DVD has a capacity of about 8 GB in total. Therefore, audio data compression is very important. However, there is a constant loss in audio compression. The AC-3 method is often used for compression. Like other audio compression methods, AC-3 removes sounds that are not perceptible to human hearing, thereby reducing the amount of information stored.

Bitrate in AC-3 reaches from 32 to 640 Kbps. In the cinema, the Dolby Digital bitrate is 329 Kbps, on DVD with 5.1 sound - 384 or 448 Kbps.

Dolby Digital Technologies

Dolby Digital EX

EX is a prefix used to refer to Dolby Digital sound systems with 7.1 channels: two front, center, bass, two surround back, and two front surround.

Dolby Digital Surround EX

Dolby Digital Surround EX adds a third surround sound channel to the audio track. The idea belongs to the sound engineers of the Skywalker Sound studio. The technology was developed in collaboration with Dolby Laboratories and Lucasfilm THX.

Dolby Digital Live

Dolby Digital Live (DDL)- Real-time encoding technology for multi-channel (5.1) audio signal in AC3 format, proposed by Dolby Technologies. Designed to transmit multi-channel audio from games and other applications to the receiver via the S/PDIF interface (optical or coaxial). Its use allows you to get rid of the restrictions due to which only ready-made (i.e. stored encoded in AC3 or DTS format) multi-channel tracks, which are usually the soundtrack of films, could be transmitted over digital interfaces, and in games the digital output was limited to the usual stereo sound.

Dolby Digital Plus

MIPS Technologies and Dolby Laboratories have unveiled a new audio technology for high-definition video and audio devices such as HD DVD and Blu-ray players. The audio technology is called Dolby Digital Plus and can be used in MIPS32 microprocessor cores.

Also, Dolby Digital Plus will improve the quality of recording audio content on HD DVD and Blu-ray Disk media, thanks to the support of even more channels than was possible with Dolby Digital. The companies will present to developers of SoC solutions (System-on-Chip) varieties of the integrated Dolby Digital Plus codec based on the MIPS core.

Peculiarities:

• Multi-channel audio with independent channels
• Supports up to 7.1 channels* and the ability to have multiple audio programs in one stream
• Dolby Digital stream output for compatibility with older devices
• Maximum bit rate up to 6 Mbps
• Bitrate from 3 Mbps on HD DVD and up to 1.7 Mbps on Blu-ray Disc
• Supported by HDMI
• One stream can contain material in different languages
• New Coding Options for Audio Professionals
• Maintaining high quality at more broadcast-efficient data rates (200 Kbps for 5.1 channels)

Dolby Digital Plus supports more than 8 audio channels. The HD DVD and Blu-ray Disc standards currently limit this number to 8.

Dolby TrueHD

Dolby TrueHD is one of the first two uncompressed (lossless compressed) audio formats available only for optical HD players. Although the Dolby TrueHD codec is optional, the format is widely supported by Blu-ray players and discs.

Dolby TrueHD uses the Meridian Lossless Packing (MLP) lossless compression algorithm. A Dolby TrueHD digital stream can hold up to 14 separate audio channels, but in practice works with 6 (5.1) or 8 (7.1) channels.

The characteristic of a Dolby TrueHD track for Blu-ray movies is as follows:

• Audio codec - Dolby TrueHD.
• Channels (sound scheme) are almost always 5.1, 6.1 and 7.1 are very rare.
• Clarity data is often not available, but the usual values ​​are: 16 bits at 48 kHz or 24 bits at 48 kHz; for some live discs, these values ​​are 24 bits at 96 kHz.
• The stream value is usually not available, but is typically 4608 kbps (4.5 Mbps, corresponding to six channels at 48 kHz and 16 bits). The highest we've seen on commercial live Blu-ray discs is 9.0 Mbps, which is six channels at 96 kHz and 24 bits. The maximum value for Blu-ray is 18 Mbps.

Dolby Digital - General Information

Dolby Digital sound first hit theaters in 1992 with the premiere of Batman Returns, and has since been featured in almost a thousand films worldwide, and is one of the most recent developments from .

Dolby revolutionized tape recording systems in the late 60s and early 70s with its Dolby A (professional) and Dolby B (common user) noise reduction system. Later, in the 1970s, Dolby revolutionized film sound with its analog Dolby Stereo system.

Dolby Stereo brought 4 sound channels to movies, with three in front (left and right for music and effects, and center for dialogue) and a fourth "surround" (Surround) to create an overall sound atmosphere. Later, in the 80s, thanks to the Dolby SR ("Spectral Recording") system, the quality of tape recording and sound in movies was significantly improved.

Also, Dolby revolutionized consumer entertainment devices in the late 80s and early 90s with the introduction of Dolby Surround home theater systems, and later Dolby Pro Logic. Consumer devices mainly use Dolby Stereo technology to play video tapes and laser discs (hereinafter, laser discs mean LaserDisc, i.e. "large" video laser discs). These systems allowed viewers to use the same 4-channel configuration at home as they would in theaters.

Modern Dolby Digital systems have gone to the next level, delivering six channels of crystal-clear digital surround sound. Left, center and right front channels allow you to accurately determine the position of the sound source on the screen. Separate "split" left and right surround back channels draw you into the movie with their surround and wraparound sounds. And an additional low-frequency channel adds heat to the action on the screen.

The principles of Dolby Digital are derived from Dolby's developments in analog noise reduction. Dolby noise reduction works by attenuating noise when there is no audio signal, and when there is, allowing the stronger wanted audio signal to override the weaker noise. Thus, this technology takes advantage of the psycho-acoustic phenomenon known as auditory masking. Even if the audio signal only occupies part of the spectrum, Dolby noise reduction reduces the noise level in those parts of the spectrum in which there is no useful signal, making the noise invisible. This is done because the audio signal can only mask near-frequency noise.

When moving from analog recording of a signal to recording on a digital medium such as a CD, it is found that the digital encoding of audio signals used in CDs produces too much data to be efficiently stored or transmitted electronically, especially in cases where it is necessary encode multiple channels. As a result, new forms of digital audio coding - collectively known as "perceptual coding - sensitive (receptive) coding" - have emerged that have been developed so that low bit rate data streams can be used with minimal perceived loss in audio quality. An example of such an encoding algorithm is the third generation of Dolby encoders - AC-3.

This encoder has been designed to take full advantage of the human ability for sound masking by splitting the audio spectrum in each channel into narrow frequency bands of varying sizes, optimized for the frequency selectivity of human hearing. This allows very precise filtering of digitizing noise so that it is very close in frequency to the frequency components of the desired audio signal. By reducing or even completely eliminating noise where there is no masking audio signal, the sound quality of the original signal is not subjectively affected. In this key aspect, coding such as AC-3 is a form of very selective and high quality denoising.

Dolby Laboratories' unique expertise in eliminating audio noise is critical to reducing data flow in AC-3 technology: the fewer bits used to describe an audio signal, the more noise associated with the encoding itself.

In the film industry, the Dolby Digital soundtrack is optically encoded directly onto the film in the gaps between the perforations. Placing the digital audio track on the same medium as the film allows it to co-exist with the analog track without the need for additional storage media such as CDs. This simplifies production and, for theater owners, the use of films, and allows Dolby Digital track preparation at virtually no additional cost. Because the punched portion of the tape is manufactured to be highly resistant to wear and tear, the Dolby Digital track will not crack or hiss over the lifetime of the tape.

In consumer electronics, Dolby Digital technology can be found in the latest generation of laser discs (where there was a regular analog soundtrack), it is the standard soundtrack in DVD and is used as an audio format for high-definition television - HDTV, as well as in cable and satellite television systems .

DOLBY DIGITAL Questions and Answers

You've probably heard a lot about how Dolby Digital is the next and possibly the last evolutionary step towards realism. So what is this new technology? How is it different from Dolby Surround Pro Logic and what new hardware will it require? You will receive answers to these and other questions in this article.

But first you need to clarify the issue with the names. For the past few years, Dolby Laboratories has used the term Dolby Digital to refer to their new digital system for the film industry, while Dolby Surround AC-3 refers to home theater systems. In practice, these two systems are small variations (slightly different in data rate) of the same underlying technology. And in order not to mislead users anymore, it was decided that the Dolby format for home multi-channel systems was also called by the same name as in the film industry - Dolby Digital.

This is believed to help consumers more easily determine whether a product supports this technology and help distinguish it from Dolby Surround and Dolby Pro Logic, which are based on analog technologies. The new generation of laserdiscs, and the new formats used in DVD and high definition television (HDTV), will also refer to the term Dolby Digital, as is now done with professional film applications. The generic name Dolby Digital should also help end growing user confusion with the term "AC-3" (Audio Code Number 3), which is the technical designation for Dolby technology designed for multi-channel applications.

I heard about Dolby Surround Pro Logic, but what is Dolby Digital (AC-3)? and what is Dolby "5.1"?

Dolby Digital provides a total of six separate channels of audio. Like Dolby Surround Pro Logic, it includes left, center and right channels at the front of the room. Dolby Surround Pro Logic provides an additional band-limited channel (100 to 7000 Hz) for surround ("surround") sound, which is typically amplified through two amplifier channels and then fed to two speakers. Whereas Dolby Digital provides separate left and right surround channels for more precise location of sounds and more natural, realistic atmospheres and backgrounds. And on top of that, all five main channels transmit a full range of frequencies (from 3 to 20,000 Hz), to which you can add low-frequency speakers (subwoofers).

The sixth channel - Low Frequency Effects Channel (channel for low frequency and effects), sometimes contains additional low-frequency information to enhance the effect of certain scenes, such as explosions, disasters, etc. Because this channel is highly limited in frequency (from 3 to 120 Hz), it is sometimes referred to as the ".1" channel. If it is added to the full 5 channels of Dolby Digital, then such systems are said to have "5.1" channels.

All six channels in a Dolby Digital system are fully digital, which means they are transmitted without loss of quality all the way from the sound engineer's desk to your home system. But Dolby Digital also packs them all into one channel, which takes up less space than one channel on a CD. This is what makes it so easy to add Dolby Digital soundtracks to conventional laser discs, as well as to many other sources. Dolby Digital has been around for years to let you watch Dolby Digital movies, and now, with the advent of Dolby Digital on laserdisc, you can enjoy this great technology in your own home. And since it was developed by Dolby Laboratories, you can be sure that the sound will be amazing!

Is it true that Dolby Digital requires a bunch of new hardware?

If you're building a new system, you can buy amplifiers and speakers specifically designed for Dolby Pro Logic that will work with Dolby Digital. You will need a new generation laser player that has a Dolby Digital RF output (it outputs a Dolby AC-3 data stream). The main new device you will need is a Dolby Digital decoder (to decode the AC-3 stream for later playback). If you already have a Dolby Surround Pro Logic system, then you probably already have a five-channel amplifier, as well as the required number of speakers. It is recommended to add a subwoofer, maybe even several.

Where do you record a Dolby Digital track on a laserdisc? Does this remove any important audio information from the laserdisc? Should I change my entire laserdisc library now?

There are more similarities between "normal" and "new" laserdiscs than there are differences. New laser discs, including Dolby Digital discs, are fully compatible with your existing player. The two digital (PCM) tracks remain unchanged, so you can continue to enjoy Dolby Surround Pro Logic quality from the "new" discs. The Dolby Digital track is recorded instead of the right analog (FM) track of the disc. The left analog track can contain a mono version, commentary, or any other audio material.

The last players that could only play sound from analog (FM) tracks were released more than 10 years ago. Since then, virtually all players have been able to use higher quality digital (PCM) tracks for stereo or Dolby Surround playback. Of course, all new AC-3 laser players will play all the laser discs you own, both digital and analog audio tracks.

Does Dolby Digital make Pro Logic unnecessary?

Not at all. Dolby Surround Pro Logic will be with us for a long time to come. Dolby Surround Pro Logic stacks four channels (Left, Center, Right and frequency-limited Surround) into two channels. In mono systems, these two channels are added together for playback. And of course all the information is available for playback in stereo systems. But when these two channels are fed into a Dolby Pro Logic decoder, the sound matrix "unfolds" and all of the original four channels become available (the "surround" channel is played through separate left and right "surround" speakers).

The most amazing part of the Dolby Surround Pro Logic system is that the original signal, "stacked" in stereo, can be carried along with it wherever it is possible to transmit a stereo signal: stereo TV broadcasts, via satellite (C-band, DSS or PrimeStar), cable broadcasts, VHF (FM) radios, laser discs, video tapes, and even some game consoles. Today you can listen to Dolby Surround sound on a variety of regular TV programs, on a growing list of CDs and of course on VHS and Laserdiscs, which contain thousands of Dolby Stereo movies (the term Dolby Stereo means the same as the well-known Dolby Surround, but used in the film industry). So as long as we have stereo, there will be Dolby Surround Pro Logic, and that's why all Dolby Digital decoders have a built-in Dolby Pro Logic decoder.

The following table compares the features of Dolby Digital and Dolby Surround Pro Logic.

Parameter	Dolby Digital	Dolby Surround Pro Logic
"Surround" channel	Stereo, full frequency (3-20000 Hz)	Monophonic, limited spectrum (100-7000 Hz)
Low frequency channel	Yes (3-120Hz)	No
Pan	Miscellaneous	Left to right, right to left, front to back and vice versa.
Channels	6 separate, all channels can be active simultaneously and independently.	4 derivatives, only one dominant signal can be reproduced at a time.
Miscellaneous	Improved sound picture, thanks to "time alignment - alignment in time", i.e. makes the speakers sound like they are the same distance from the listener.	An economical solution to the problem of obtaining high-quality surround sound.
	When the overall volume is lowered in the soundtracks of action movies (for example, when the action takes place late at night), the compression is adjusted accordingly, so as to preserve the quality of the quiet sections.	Surround sound from any unencoded stereo source.
	The decoders can be configured to route low frequency audio to dedicated channels for systems with subwoofers.	Compatible with all existing and future stereo formats.
	A dramatic step forward in bringing the listener into the world of real sounds. Unprecedented creative possibilities for sound production and control.	Represents a significant step forward from conventional stereo sound. It is the world standard.

At the moment, there are a huge number of sound sources that support Dolby Pro Logic. What about Dolby Digital? What else can you record with Dolby Digital besides laser discs?

Dolby Digital has one great thing about it - great encoding flexibility. Dolby Digital technically allows a huge variety of formats, and some of them will appear in the very near future:

High Definition Television (HDTV). This latest system was one of the first to choose Dolby Digital as its primary audio subsystem. The choice was made by the "Grand Alliance" - an organization that sets all standards for HDTV systems in the US.

Satellite TV - Direct Broadcast Satellite (DBS) already today actively uses such advantages of the Dolby Digital system as high quality and ease of transmission. For example, the "DMX for Business" service uses Dolby Digital to deliver 120 stereo music channels, all from a single transmitter. PrimeStar plans to add Dolby Digital to its satellite television service in the near future.

Cable TV is implementing systems with Dolby Digital for efficiency reasons and to be ready for the standards of future HDTV systems.

The Digital Video Disc (DVD) format already includes Dolby Digital.

Other formats such as Digital Video Cassette (DVC) and Digital Audio Broadcast (DAB) are first on the list for the unique combination of sound quality, efficient full spectrum transmission and Dolby Digital's multi-channel capabilities.

What makes Dolby Digital so flexible, or to put it bluntly, why is it so good?

The letters "AC" in Dolby AC-3 stand for Audio Coding - sound coding. Digital audio coding is often referred to as "perceptual coding" (sensation-based coding). Simply put, this is an encoding that tries to detect and then remove that audio information that we still cannot hear, but retains what we can hear. Its purpose is to fit as much useful information as possible in the available spectrum. Consider an analogy:

Let's assume that you need to deliver 4000 people (useful information) from one place to another within an hour. Only 1000 cars per hour can pass on the highway. If you put all 4,000 people in 1,000 cars, then you can get rid of unnecessary information (let's leave 3,000 cars at home). It's high performance delivery, and that's what Dolby Digital is designed to do.

One of the reasons why the sound quality on a CD is so high is because it contains a huge amount of data: 16-bit samples are sampled 44,100 times per second, separately for each channel. This corresponds to a stream of 1411200 bits per second. A CD is such a large repository of information that it can store up to 74 minutes of music on one disc. But what to do if you need to record 2 hours of a 20-bit signal and, in addition, there should be six channels? Today, such a large data stream is impractical for either storage or transmission.

The Dolby Digital encoder is the first encoder designed specifically for multi-channel audio. Dolby Laboratories' unique expertise in eliminating audio noise is critical to data reduction because the fewer bits used to describe an audio signal, the more noise.

Dolby noise reduction works by reducing the level of noise in the absence of an audio signal, as well as allowing a stronger wanted audio signal to override or "mask" the noise. But this allows masking only noise close in frequency to the useful signal. Therefore, Dolby Digital breaks the audio spectrum for each channel into narrow strips of different sizes, optimized for the frequency selectivity of human hearing. This allows very precise filtering of the digitizing noise so that it is very close in frequency to the frequency of the encoded signal. The audio signal effectively muffles the noise, making it inaudible to the ear. Where the absence of a signal makes it impossible to mask digitizing noise, Dolby Digital makes every effort to reduce it. We can say that Dolby Digital is a very effective noise reduction system, and as a result the sound quality is subjectively very close to the original.

Dolby Digital uses "shared bitpool" technology, and also a human hearing masking model, to achieve the most efficient transmission of data. The bits are unevenly distributed between a plurality of narrow frequency bands, and in each specific case differently, depending on the spectrum and dynamic structure of the encoded signal. By applying an auditory masking model, the encoder provides the optimal number of bits for the audio signal in each band. Additionally, there is a redistribution of bits between different channels in accordance with the model, according to which a more saturated channel will require more data for transmission than other, weakly filled ones, and it is also taken into account that a strong signal in one channel can mask the emerging noise in other channels. As a result, Dolby Digital can use proportionately more transmitted data to encode audio, producing a better signal and allowing multiple audio channels to be encoded into lower bit rates than even a single channel on a CD would require.

TECHNICAL DATA

The Dolby Digital encoder is capable of processing at least a 20-bit dynamic digital input signal with a frequency range of 20 to 20,000 Hz ±0.5 dB (-3 dB at 3 and 20,300 Hz). The low frequency channel covers the range from 20 to 120 Hz ±0.5 dB (-3 dB at 3 and 121 Hz). Sampling rates of 32, 44.1 and 48 kHz are supported. The output data stream width can vary from a minimum of 32 kbps for a single mono channel to a maximum of 640 kbps to suit the full range of requirements. Typical speeds are 384 kbps for consumer "5.1" Dolby Digital, and 192 kbps for two-channel audio.

Also known as:

In 1965, American physicist and engineer Ray Dolby founded Dolby Labs in London. He worked on the idea of ​​creating noise reduction systems that would improve the sound quality. The technology had to be suitable for both professionals and the general public. Since then, the name Dolby has become known around the world, and the surround sound standards created in the laboratory are used both in cinemas and in the homes of our citizens.

Dolby Digital sound first hit theaters in 1992 with the premiere of Batman Returns, and has since been featured in almost a thousand films worldwide, and is one of the most advanced developments from Dolby Laboratories.

Dolby Digital 5.1 is also called AC-3 (Audio Code-3). The standard provides for six channels - two in the front, two in the rear, one in the center and one for the subwoofer. Unlike Dolby Surround And Dolby Prologic, here the bandwidth has been extended from 20 Hz to 20 kHz. 5.1 means five front and rear channels plus a subwoofer. Dolby Digital sound can be recorded in five separate full frequency channels - left, right, center, right effects channel, left effects channel, at the request of the manufacturer. In addition, there is an additional channel of powerful low-frequency effects (LFE, low-frequency effects) that are more felt than listened to. Since this channel has ten times the bandwidth, the LFE channel is called.1

As its name implies, Dolby Digital is a digital format, that is, it involves recording sound information in the form of a sequence of zeros and ones. Dolby Digital is different in that it has six discrete (separate) audio channels. Their discreteness eliminates the possibility of unwanted leakage of sound from one channel to another. The subwoofer channel is also called LFE (Low Frequency Effects). The term AC-3 refers to an audio coding technology that discards the inaudible sound and decomposes the rest into six channels. Accordingly, to play Dolby Digital sound, you need an external decoder, or a sound card that decodes 5.1 sound and is equipped with the appropriate outputs.

This encoder has been designed to take full advantage of the human ability for sound masking by splitting the audio spectrum in each channel into narrow frequency bands of varying sizes, optimized for the frequency selectivity of human hearing. This allows very precise filtering of digitizing noise so that it is very close in frequency to the frequency components of the desired audio signal. By reducing or even completely eliminating noise where there is no masking audio signal, the sound quality of the original signal is not subjectively affected. In this key aspect, coding such as AC-3 is a form of very selective and high quality denoising.

When moving from analog recording of a signal to recording on a digital medium such as a CD, it is found that the digital encoding of audio signals used in CDs produces too much data to be efficiently stored or transmitted electronically, especially in cases where it is necessary encode multiple channels. As a result, new forms of digital audio coding - collectively known as "perceptual coding - sensitive (receptive) coding" - have emerged that have been developed so that low bit rate data streams can be used with minimal perceived loss in audio quality. An example of such an encoding algorithm is the third generation of Dolby encoders - AC-3.

Dolby Digital uses audio compression at a fixed 1:2 ratio. In other words, whatever sound you take, after compression, you will receive a strictly defined stream. There are pluses (disk space) and minuses here - since the sound quality is still deteriorating. However, as a result, the sound does not take up much space on the DVD, which allows you to add translation into different languages ​​and various bonuses. AC-3 uses 18-bit encoding, so the output stream of AC-3 is 384 kbps. To restore the sound image, the Dolby Digital decoder adds a 1ms delay to the front channels, since the listener is often closer to the rear speakers than the front ones. The delay allows you to balance the sound picture. Some decoders allow you to change the delay.

Dolby Digital sound can be obtained from laser discs, DVD-Video discs, some computer DVD-ROM discs, digital cable and satellite programs, and digital TV broadcasts (DTV). Usually programs containing Dolby Digital are marked with special symbols.

A Dolby Digital soundtrack cannot be recorded on a conventional VHS tape (however, as an experiment, it was recorded on S-VHS). Dolby Digital has been chosen as the standard for high definition television. Dolby Digital can also be transmitted using a digital satellite television system, although in this case you will need a dedicated Dolby Digital digital receiver to receive audio.

The main advantage of the standard lies precisely in the fact that Dolby Digital has become the standard for surround sound on DVD. The description of the DVD standard states that a disc cannot use other audio technologies unless it has a dedicated Dolby Digital track. So you will never find a disc with just DTS. Therefore, Dolby Digital is universal.

Predecessors of the Dolby Digital standard:

• Dolby Surround- three channels, two for front sound, one for rear sound. The range of transmitted frequencies is from 100 Hz to 7 kHz.
• Dolby Pro Logic- Improvement of Dolby Surround by increasing the number of channels to four, including the center channel, and using one or two elements for the rear sound.

Dolby Digital soundtracks have a very wide dynamic range between quiet and loud passages. At full volume, you can hear the trembling that provides a true theater experience. However, late at night, loud movie soundtracks can annoy other family members or neighbors. But if you lower the overall volume to "restore peace and tranquility", then the dialogue can be very hard to hear, and the ambient sound will disappear altogether. What you really want in a situation like this is to turn down the loud effects, turn up the volume of the quiet passages, and keep the volume of the dialogue. This is exactly what the Dolby Digital dynamic range control system allows you to do. For listening at low volumes, it applies dynamic band compression, preserving quiet sounds, preventing overly loud effects, and keeping dialogue loud. To make this feature easier to understand, Dolby Digital equipment manufacturers called it Midnight Mode.

The Dolby Digital encoder is capable of processing at least a 20-bit dynamic digital input signal with a frequency range of 20 to 20,000 Hz ±0.5 dB (-3 dB at 3 and 20,300 Hz).
The low frequency channel covers the range from 20 to 120 Hz ±0.5 dB (-3 dB at 3 and 121 Hz).
Sample rate in 32, 44.1 and 48 kHz.
The output data stream width is from 32 kbps for one mono channel, up to a maximum of 640 kbps.
Typical speeds are 384 kbps for consumer "5.1" Dolby Digital, and 192 kbps for two-channel audio.

Dolby Digital is a built-in decoding device that creates six-channel audio for satellite digital broadcast programs or multimedia video content recorded on a digital video cassette, digital audio cassette, or video server.

What is a dolby digital decoder on a TV

The Dolby Digital decoder is presented as a system of perfectly clear sound. Channels (left - center and right - front) allow you to set the location of the sound source. Separately distributed channels captivate the viewer with sounds covering and pouring from the screen.

Why you need a dolby digital decoder on your TV

The Dolby Digital processor is an extension of the Dolby multi-channel audio encoding system that was previously implemented. In the absence of a noise reduction signal, Dolby works on the principle of noise reduction, and in the case of its presence, it allows a powerful productive audio signal to interrupt the noise of a lower level. That is why this technology uses a psychoacoustic model of hearing.

Attention! In the event that the signal fills a separate part of the spectrum, Dolby noise reduction reduces the noise level in certain parts of the spectrum in which there is no productive signal, making it insignificant. This is because the audio signal hides only nearby frequency noise.

The Dolby Digital set-top box embraces many other reserves:

• increases the resources of the device, guarantees the transmission of high fidelity sound in 5.1 format;
• Produces true 5.1 stereoscopic sound using a variety of stereo headphones;
• increases the sound distance when using speakers for musical sound reproduction;
• produces a spatial perception when using stereo headphones.
• amplifies low sound frequencies;
• amplifies high frequencies and improves the quality of sound conduction of music by correcting the effects of high-frequency impulses;
• adds significance to mono sound reproduction;
• controls the sound level by maintaining a stable volume level.

How to use the dolby digital decoder

In order to set up a system device, the TV must support the standard settings.

However, video recordings must also comply with the DD+ format. As a rule, it is used in all BluRay and on certain commercial channels.

You will need a standard HDMI 1.3 cable to transfer Dolby Digital Plus video content from your video player to your TV and then to your multimedia system equipment.