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Sound Formats


Here All Important Sound Formats Briefly And Concisely Explained


A single-channel sound recording.


A two-channel recording.

Dolby Axon

Axon will make it possible to transmit speech in 3D in video games in the future. This will make it possible to recognize from which direction another player is coming or speaking to you. Distance, obstacles, and other factors will be taken into account. Through Dolby Axon and the Voice Font, it will also be possible to change or completely manipulate voices. Dolby Axon uses a bandwidth of 16Kbit/sec and can let up to 7,000 players communicate with each other. At GDC, the technology was demonstrated using the game Jumpgate Evolution, which will be released for PC. The use of consoles would also be possible.

Dolby Surround Pro Logic

This multi-channel format can also be played on normal stereo equipment. There is an additional surround channel to the right and left, which is limited from 100 Hz to 7 kHz and is given to the rear speakers in mono. Since the surround signal is extracted from the two stereo channels, the surround effect is weak. Many TV movies are broadcast in this format, which has been around since 1987.
Dolby Prologic requires rear speakers that cannot be located. You can direct them against the rear wall for additional reflections. They transmit a narrow frequency band and both are fed with the same signal. So it’s no problem to use “modest” things.
With Dolby Digital or discrete 5.1, there are 5 equal channels. This means that ALL 5 channels are equipped with the same speakers. Only in an emergency, with an extreme lack of space, a smaller version of the same speaker is used. In the studio, for example, 3x Genelec 1032, 2x 1030.

dolby surround

Dolby Surround Pro Logic II

Here, the rear channels are without frequency restriction. The bass response to the subwoofer is improved. The surround channels are stereo. This format has been around since 2000.

Dolby Surround Pro Logic IIx

With Dolby Pro Logic IIx you can convert stereo or 5.1 signals into 6.1 or 7.1. There are different modes: Movie/Music with parameters like Dolby Panorama, Dolby Dimension, Dolby Center as well as a special Game mode.

Dolby Surround Pro Logic IIz

To use Pro Logic IIz, you need to add two additional speakers to an existing 5.1 or 7.1 setup (9.1 system). The new speakers are located above the right and left front speakers, just below the ceiling, which is why they are also called “height speakers”.
With Pro Logic IIz, stereo or 5.1 material can be used as the source. The new system also works with existing 7.1 speaker configurations, so after the upgrade, you’ll end up with 10 speakers (7 main speakers, 2 treble speakers, and a subwoofer) in your living room.

Logic 7

A system developed by Harman/Lexicon for effective surround presentation even of stereo or Dolby Pro Logic material.


The analog Dolby Surround supplies the two rear surround speakers with the same sound effects. The digital AC 3 signal, on the other hand, contains separate information for each speaker in the surround system, which the AC 3 decoder feeds to them via six discrete channels. Result: more sophisticated effects, such as a gunshot hunting across the room. In addition, the digitally delivered audio has higher sound quality. Dolby Digital signals are currently only supplied by DVDs and laserdiscs.

Dolby Digital

This sound format is available in different variations: 1.0, 2.0, …, 5.1. The digit after the dot indicates whether there is a channel for the subwoofer (0 = none, 1 = there is a channel). 1.0 means mono, 2.0 means stereo, 5.1 means left, center, right, surround left, surround right, subwoofer.
Abbreviated channel names: L, C, R, SL, SR, LFE.
The sampling frequency is 48 kHz at a maximum of 24 bits. Bit rate varies from 64 kbps up to 448 kbps. 384 kbps is the normal rate for 5.1 and 192 kbps for stereo.
Lossy compression compresses by a factor of 12.
The subwoofer channel, if present, goes from 3 to 120 hertz, though the 3 Hz is an optional requirement, meaning not everyone will adhere to it. This format has been around since 1992.

Dolby Digital EX

This is the home version of Dolby Digital Surround EX.
Here Dolby Digital 5.1 is supplemented by a third surround channel, the rear center.
This format has been around since May 1999.

Dolby Digital Live

Dolby Digital Live is a real-time encoding technology that converts any multichannel audio signal into a Dolby Digital data stream. With its help, audio signals can be transferred from the PC to Dolby Digital receivers or complete home theater systems via a single digital connection. Cumbersome multiple connections and tangled cables are now a thing of the past. One touch of the input selector on the AV receiver is all it takes to playback any PC audio material through the system.

Dolby Digital Plus

Dolby Digital Plus is a powerful next-generation audio codec that sets new standards in digital sound quality. This includes higher fidelity and an expanded number of channels, as well as technology specifically designed for future broadcast and streaming offerings. Building on Dolby Digital technology, Dolby Digital Plus is specifically designed to meet the changing needs of audio and video services and new storage media.

Dolby Digital Pulse

Dolby Pulse is a total system that includes a bitstream format and proprietary encoding and decoding solutions. Compatible with the Open Standard Audio Codec MPEG-4 HE-AAC, Dolby Pulse leverages Dolby’s content delivery expertise for new developments on a variety of platforms including HD TV, cell phones, portable players, PCs, and online entertainment. It also offers enhanced bitrate utilization with HE AAC.

With true Dolby metadata capability, Dolby Pulse enables a single 5.1 stream to handle multichannel, stereo, and mono signals with seamless switching. This eliminates the need for bandwidth-intensive simulcasting. Meanwhile, dialnorm values embedded in broadcast streams establish loudness while preserving dynamic range. This means that Dolby Pulse can provide metadata features equivalent to Dolby Digital and Dolby Digital Plus, giving consumers an excellent experience and providing a highly efficient solution for broadcasters.

In a broadcast landscape that now includes IPTV, mobile, and Internet, as well as terrestrial, cable, and satellite TV, Dolby Pulse is an important addition to Dolby’s audio solutions. The company aims to implement Dolby Pulse throughout the broadcast chain â�� in hardware, OEM products, and licensed encoding and decoding solutions. Dolby Pulse complies with new HDTV specifications established by major European industry bodies such as EICTA, the French and Spanish HD Forums, and NorDig.

Dolby Digital Surround EX/h2>
This is the cinema version of Dolby Digital EX.
Here Dolby Digital 5.1 is supplemented by a third surround channel, the Rear Center (SRC).
This format has been around since May 1999.

dolby digital digital ex

Dolby E

This format is the format in which you can cut lossless or frame-accurate, and in which no data is lost. In television and radio and in the production of films with DD, everyone worldwide should actually work with this format, if you can believe the advertising of the company Dolby. As the last step of DD production, Dolby E is then converted into the actual format DD, DTS, DVD-A, etc.

Dolby Headphone

Refers to a technology that enables the listening impression of a 5.1 surround system via conventional stereo headphones.
The technology used corresponds to a virtual artificial head. Here, the sound from each of the 5 sound channels is digitally distorted in such a way that the brain perceives it as coming from a certain direction, e.g. from a loudspeaker behind the listening position. In contrast to previous solutions, Dolby Headphone also incorporates the acoustic structure of the imaginary room by simulating a reverberation as well as adjusting the time delay of the individual, virtual sound sources.
Although humans can locate sounds with two ears from all 3 dimensions, sound technology now uses up to 7 loudspeakers to represent a room sound. With Dolby-Headphone it is achieved to reduce the technology again to 2 “loudspeakers” within the headphones, but so far only the hearing impression of a 5.1 system is achieved.

Dolby Home Theatre V3

Dolby Home Theater v3 is a technologically advanced suit that enables desktop PCs and laptops to conjure up a cinema-like listening and viewing experience at home or on the go. Thanks to powerful and advanced digital signal processing technologies, Dolby Home Theater makes it possible for listeners and viewers to experience music, movies, and games in vivid surround sound when connected to 2 to 6 speakers or headphones.

Dolby Volume

Everyone knows the situation: The feature film goes into the commercial break and this is much louder than the feature film – a marketing tactic so that viewers perceive the advertised products better. But sudden explosions after long, quiet dialogues also cause many viewers to reach for the remote control. Dolby now remedies these problems with Dolby Volume.
This sound format works on two levels: The “Volume Leveler” compares the current sound spectrum with previous ones. Dolby uses techniques from the professional field, such as an “auditory scene analysis”. This technique recognizes which sounds need to be boosted and which do not. For example, Dolby Volume does not turn up the volume of a decaying piano chord.

The second layer is the “volume modeler”, which response to the fact that the human ear perceives highs and lows less well at low volumes. In old stereo amplifiers, there was a loudness button for this. However, it ignored the actual volume and often distorted the original signal to a sound mush.

The Volume Modeler relies on the knowledge of data compression that came with the invention of MP3 or Dolby Digital: Sound data that is below the audible threshold is simply omitted there. The Volume Modeler does the exact opposite: it raises the volume of sound components whose volume is below the audible threshold, thus aiming to make the sound full and detailed even at low volumes.

Unlike previous volume control solutions, Dolby Volume does not introduce audible artifacts or side effects. For example, the volume of quiet background noises between dialog scenes is not increased or reduced, as is the case with conventional compression technologies.

In addition to AV receivers, complete home cinema systems, and stereo systems, Dolby Volume can also be integrated into television sets. Dolby Volume works with any input signal, analog or digital, with any service (cable, satellite, terrestrial, and IPTV) and for any program source. The first AV receivers and complete home theater sets will be launched before the end of 2008.

Dolby True-HD

Dolby True-HD describes an audio codec developed specifically for the growing HD market and designed for use on Blu-ray discs as an optional, lossless surround sound format. The codec supports up to eight channels (equivalent to 7.1) with 24-bit samples and a sampling rate of 96 kHz. If fewer than 8 channels are used, the sampling rate can be increased to 192 kHz. The maximum data transfer rate is 18 MB/s.

Lossless because the digital data stream is 100% bit-exact to the mix of the sound engineer when mastering the film.

It is based on MLP (lossless compression algorithm for digital sound recordings) and sees itself as its successor. The transmission takes place via HDMI 1.3.


A format with the same channel division as Dolby Digital, mostly 5.1.
DTS works with a constant bitrate from 64 to 1536 kbit/s, on the DVD with 384 or 448kbit/s, the sampling rates go from 48 to 192 kHz with up to 24 bits. On the DVD there is compression, lossy, with factor 4.
On many DVD players, if you take a cursory look, you’ll see a DTS icon on the front panel, but many of these DVD players don’t have a DTS decoder at all. If you look closely, you’ll see the text “Digital Out” under the DTS. This means that you have to use a receiver/amplifier with a DTS decoder to enjoy dts.
The subwoofer channel goes from 20 to 80 Herz.
This format has been around since May 1993.

dolby digital 5.1


In 5.1, an additional channel for „Surround Rear Center“ is obtained from the other channels here, so it is not a true 6.1 format.

DTS ES 6.1 Discrete

Here, the “Surround Rear Center” channel is saved as a separate channel, making it a true 6.1 system.

DTS ES 6.1 Compatible

This is a designation of a device about its way of generating the 6th channel by matrix from the other channels without an official DTS license.

DTS ES 6.1 Matrix

Similar to “DTS ES 6.1 Compatible”, this is an economy version of DTS ES 6.1 Discrete.

DTS 24/96

A 24-bit, 96 kHz multichannel format with up to 6 channels, uncompressed as opposed to Dolby Digital.

DTS Neo6

A similar process to Dolby Surround Prologic II. DTS Neo6 is supposed to be better, though: Up to 7 channels: separate subwoofer channel in stereo, EffectRearCenter as well as effect speakers with full frequency range.

DTS-HD Master

DTS-HD master stands for “Digital Theater Systems High-Definition” and describes a lossless audio codec developed specifically for the growing HD market with data rates of up to 6 Mbits/s (as a comparison: DVD 768 â?? 1,536 Kbit/s), backward compatibility with DTS, an unlimited number of channels and a sampling rate of 192 kHz.
Lossless because the digital data stream is 100% bit-exact to the mix of the sound engineer when mastering the film.

DTS-HD Master Audio covers 18 MB/s on HD-DVD and 24.5 MB/s on Blu-Ray discs. In addition, it allows the sound master of the theatrical movie to be reproduced accurately, which was not possible with the predecessor DTS due to the high bandwidth of the sound master. It also supports low data rates, so additional audio tracks or audio commentaries can be stored as extensions and added to the main audio core. This core audio track is compatible with DTS; once the extension is added, it can only be output directly through the HDMI output as 7.1 or downconverted in real-time to DTS compatible 5.1 channels.

Audio can be output analog via all standard outputs, but one cable is required per channel. Digital signals can only be transmitted via HDMI 1.3 with DTS-HD Master unchanged. HDMI 1.0 and 1.2 can only pass on DTS HD in PCM resolution. Via optical and coaxial SPDIF (interface specification for the transmission of digital audio signals), there is only the possibility of downsampling to 5.1 channels as well as a maximum bit rate of 1509.25 KB/s.

Circle Surround II by SRS

Comparable to Dolby Pro Logic II, the Circle Surround technology developed by the American company SRS Labs also offers the possibility of playing back stereo or analog Dolby Surround sources via 5.1 channels. Circle Surround II (CS II) is advanced, even more, powerful surround matrix decoding technology that generates up to 6.1 channels from mono, stereo, Dolby Surround, and Circle Surround sources.


A multichannel format with different bit rates (20 and 24bit), sampling frequencies (48 kHz, 96kHz, 192 kHz), and channels 2 to 8.


The 2+2+2 multichannel process is a recording and playback process developed by mdg, compatible with stereo and surrounds playback. While only two-dimensional reproduction is possible through the stereo and surrounds playback, the 2+2+2 multichannel process not only enables three-dimensional sound reproduction but also provides “optimal listening positions” throughout the room.
For the 2+2+2 multi-channel playback, please use the existing stereo speakers (front right and left) and the rear speakers (rear right and left). In addition, mount another pair of speakers directly above the two front stereo speakers.
For three-dimensional playback, connect the signal of the center speaker to the upper left speaker and connect the signal of the subwoofer to the upper right channel.


SACD has been around since March 1999.
The sound format (rather a sound recording format) is called DSD (Direct Stream Digital), and the data carrier on which this format is stored in the SACD. Technically, the SACD is a DVD.
DSD is a recording format in which from sample value to sample value (at the rate of 2.8 million samples/second) a change of no more than one bit is stored at a time. The precision with which sampling is performed is 24 bits.
The 2.8 MHz sampling frequency is not directly comparable with those of the other formats. There are 2.0 and 5.1 channels and multi-layer data carriers (hybrid) where a normal CD can also be played. If an SACD player has a digital SPDIF output, then this is currently (as of May 2003) only ever active when playing CDs; for SACDs, it is switched off. Addendum January 2004: now there are devices on the market where the digital data stream can be transferred via iLink (IEE1394 or also called Firewire) from the player to a receiver/decoder.
The developer’s Sony and Philips have filed the Super Audio CD specification, which includes the conventional CD standard, in the so-called “ Scarlet Book”.


The MPEG designation applies not only to sound formats but also to image formats.
For video: System for data-reduced coding with low picture quality. Used for CD-I and Video CD. For audio: System for data-reduced coding of up to 2 channels.


For video: System for data-reduced encoding with high picture quality. Used for DVD. For audio: System for data-reduced encoding of up to 7.1 channels.
The data rate for high-quality MPEG -2 playback for picture and sound is about 50 MB/s. A MPEG-3 format was originally envisaged for encoding the high-quality HDTV signals, but this was never implemented.


THX is not a recording format but a playback definition. It is defined by the company THX, how the speakers etc. must be so that a certain playback quality is achieved. The focus here is on the reproduction of film sound. THX does not necessarily mean Hifi and vice versa. To be allowed to use a THX logo for an amplifier or speaker combination, the THX standards must be met, these are also tested.


MP3 is not a multi-channel format, but so far only a stereo format (update: MP3 surround sound, see HiFi Knowledge). This file format is intended for storing compressed music, where what you wouldn’t hear is left out. That’s where the alarm clock example comes in: when it’s quiet, you can hear it ticking.
But as soon as the alarm clock rings, you don’t hear the ticking anymore, although of course, it keeps ticking. That’s why you can omit the ticking from a recording because no one with healthy human ears can hear it. The CD has a bit rate of about 1400 kBit/s (WAV file), with MP3 bit rates of 128 to 320 kBit/s are common, whereby many listeners no longer hear any difference to the CD at 320 kBit/s.


This is not a sound format, but the specification for an interface. SPDIF stands for Sony Philips Digital Interface and is a digital input or output for digital audio in electrical format.
General SPDIF data:
Sampling frequency CD 44.1kHz (2.8224 Mbit/s), DAT 48kHz (3.072 Mbit/s)
Bandwidth: 100kHz – 6Mhz
Signal Bitrate: 2.8Mhz (Fs=44.1kHz), 2Mhz (Fs==32kHz) and 3.1Mhz (Fs=48kHz)
Pins: Digital-In, Digital-Out, VCC +5V, Gnd
Max. Resolution: 20Bit (24Bit optional).

Music has accompanied Horst all his life. He has set up a home studio in his basement, where he regularly records tracks. On weekends, he is regularly booked as a DJ at parties. For the right equipment he is therefore always up to date with the latest technology. At hifi-online.net he is therefore the expert for speakers and all music systems and helps you with his tips to find the right product.