EP0712264B1 - Method and apparatus for multi-channel sound reproduction - Google Patents

Abstract

The sound reproduction system uses at least 3 front sound reproduction channels positioned on the left and right and at the centre and 2 surround sound reproduction channels positioned on the left and right. Each of the received sound channel signals is divided, with one part provided with an increased delay time and an altered amplitude and phase before summation with the unaltered signal parts, for supplying summated signals to each of the sound reproduction channels. pref. auxiliary sub-sound reproduction channels (LSn,RSn) are supplied with further signals obtained by similar division and summation.

Description

The invention relates to a method in the preamble of Claim 1 type described for multi-channel Sound reproduction in which the sound signals of a sound event are source-oriented and the mapping of the Allow original sound sources between recording and Playback also recorded, transmitted and multichannel may be registered for the purpose of changing this Signals before the final amplification and radiation via a Speaker arrangement with at least three front and two Surround speakers and a suitable one Device which in the preamble of claim 4 closer is defined.

Such systems and associated display devices are in ITU-R (formerly CCIR) recommendation BS.775 and in SMPTE standard PR 173 (1992) for a 3 / 2- or 3 / 4- or 3/2/1 system described.

Conventional two-channel stereo playback devices have so far been used predominantly for playback in living rooms and in small to medium-sized event or listening rooms, also in connection with image representations.
With two-channel stereo playback, however, there was previously only a very small, tubular stereo listening zone with only one reference point. Another disadvantage of two-channel stereophonic reproduction is the imaging of a center signal with limited sound and location quality, which is only possible through the formation of phantom sound sources.

It is therefore also known to use a real center signal or also real half left and half right signals (5-channel stereo) to transmit and emit separately.

It is also known to be the listener in addition to that to date usual two-channel stereo transmission and primary coverage with direct information by means of a stereo playback device also to provide spatial information that either separated or out of phase, correlated or not correlated assigned and transmitted as side signals and via additional loudspeakers distributed in the room can be emitted.

The widespread effort to get all of these signals in one summarize and transmit uniform format to the ITU-R recommendation BS.775 and the SMPTE standard PR 173 for a 3 / 2- (3/4) or 3/2/1 system.

Another proposal (Sony SDDS system) is the extension to an 8-channel system (5 front and 2 surround channels and a sub-bass channel).

It should also be borne in mind that multi-channel sound transmissions coupled with the introduction of new television broadcasting systems should be.

It is also known that has been in the film industry for years the multi-channel sound system Dolby Stereo Surround for use arrives. This 3-plus-1 system (3 front channels and 1 surround channel nested in 2 transmission / recording channels) is also offered for home use. The advantages of a center speaker in this three-channel Matrix transmission of front or primary information are - despite being used with respect to the two-channel film Matrix circuit - also proven in this system.

The difference between this Dolby stereo surround system and the recommendations mentioned exist alongside a now discrete one Center channel mainly in the different number of the surround channels.

Investigations have shown that two decorrelated Spatial information a much better supply ensure than the previously practiced a channel.

To the disadvantages, especially regarding the inadequate Supply of spatial information, to decrease, was two Playback speakers for two-channel room information, similar to that of the Keibs stereo ambiophony system (1960) common practice for two- or single-channel spatial information or similar to the later practice with the Dolby Stereo Surround System with single-channel room information, in integrated the overall display arrangement. But this variant too only brings significant advantages in the overall impression, if the defects of the direction assignment and the previously inadequate supply of listener seats can be overcome.

The shortcomings of single-channel reproduction of spatial information have been taken up again recently and led outside acceptance of the ITU and SMPTE standards for new film sound processes, where each has two-channel spatial information be used.

They are still two-channel stereo displays known, where the low frequency reproduction (up to approx. 120 Hz) by means of separate loudspeakers, so-called subwoofers, separated from the directional signals are made to measure the physical size of the limit individual speakers. In application to the The aforementioned international recommendations result 3/2/1 system or a maximum of 5/2/1 system.

Sound signal reproduction so perfected shows an improvement the playback quality with regard to the image of now three (or more) front information and regarding the Spatial information within a slightly enlarged listening zone.

Outside of this, very much in relation to the total room size small defined listening area, location errors have a significant impact more annoying. The distributed front signals are not shown in the correct direction, but only in each case heard from the nearest speaker. The two room information are differentiated to a large extent depending on space perceived.

It is also known to optimally supply large auditoriums (DE 3413 181), however this requires separate source treatment and therefore a very high effort for a Transmission and disproportionately large for small spaces is.

A surround processor is also known (WO 91 19407 A), which derives further directional and spatial information-bearing partial signals from two-channel signals by summation, which are fed to further loudspeakers in order to emit radiation via three front and two surround channels achieve.
It is an imitation that is supposed to produce a similar sound field as a result and to convey the subjective impression, ie the illusion, of how it can be generated with several discrete multichannel signals. The aim here is to derive preferably further direct signals or approximately both direct signals and spatial signals, as can otherwise only be obtained from an original sound field with appropriate effort and appropriate recording technology under appropriate conditions.

The impersonators can be different for physical reasons just approximate an optimal discrete burst of signals and never due to signal distortions to be equivalent; they are real only as makeshift solutions and are generally considered to be processors for pseudo surround Watched playback.

The disadvantage of home listening is that the listening area is too small, especially in connection with high-quality image reproduction, however, serious, because the space dependence is too big limitation means and also for the introduction of this Procedures in the home area are a major hindrance.

This multitude of suggestions and recommendations for different Applications and their constant expansion confirmed the inadequacy of the known methods described and the need for a more general solution for improved reproduction of multi-channel sound systems create.

The object of the invention is therefore to enable the defined listening zone for transmitted and recorded two-channel and multi-channel stereo signals to be enlarged for the space-independent reproduction of the spatial information while at the same time maintaining the specified directional information of the individual audio signal sources. In doing so, the loudspeakers should be able to receive favorable positions within the location distribution possibilities given by the space limits.
In particular, this is intended to increase the usable proportion of the total room size for acoustic / visual performances. This also applies to larger rooms. It should be taken into account here that by converting available program materials with less than 5 channels, pseudo-multi-channel playback relationships are to be created in connection with known methods.

This task is performed with the in the characterizing part of the claim 1 described procedure solved.

Advantageous developments of the method are in the claims 2 and 3 described.

A device specially designed to carry out this procedure is suitable, is in the characterizing part of the claim 4 described.

Further developments of this device are in the claims 6 to 9 described.

Fig. 1

einen Vergleich der Stereo-Hörzonen bei üblicher 5-Kanal-Wiedergabe und bei Anwendung der Erfindung (schraffierter Bereich);

Fig. 2

die Grundstruktur der Vorrichtung mit den Funktionseinheiten Eingangsstufen E, Eingangsmatrix EM, Bearbeitungsstufen FD, Summier- und Pegeldosierungsstufen SE, Ausgangsmatrix AM, "intelligente" Eingabe EA und einer Anzeige;

Fig. 3

eine Ergänzung durch die Funktionseinheit Konvertierungsmatrix KM;

Fig. 4

eine Ergänzung mit den Funktionseinheiten FE für die Erzeugung eines Tiefsttonkanals zur getrennten Ansteuerung eines sog. Subwoofers;

Fig. 5

eine weitere mögliche Ergänzung der Bearbeitungsmöglichkeit jedes Eingangssignals für ergänzende Wiedergabekanäle bei größeren Räumen;

Fig. 6

eine Konfiguration für die Bearbeitungsmöglichkeit aller Kanäle.

The invention is explained in more detail below on the basis of exemplary embodiments. In the accompanying drawings, the

Fig. 1

a comparison of the stereo listening zones in conventional 5-channel playback and when using the invention (hatched area);

Fig. 2

the basic structure of the device with the functional units input stages E, input matrix EM, processing stages FD, summing and level metering stages SE, output matrix AM, "intelligent" input EA and a display;

Fig. 3

supplemented by the functional unit conversion matrix KM;

Fig. 4

a supplement with the functional units FE for the generation of a low-frequency channel for the separate control of a so-called subwoofer;

Fig. 5

a further possible addition to the processing possibility of each input signal for additional playback channels in larger rooms;

Fig. 6

a configuration for processing all channels.

The main effect of the invention is that shown in FIG. 1 Enlargement of the stereo listening zone while maintaining the complex auditory impression that can be achieved with the previous Two-channel stereo on a single reference point reduced by a point in the middle of the listening zone is indicated and in the standardized multi-channel sound arrangement (3/2 arrangement) only a small enlargement of the Listening zone allows by an inner white trapeze is designated. The inner hatched trapezoid shows the Enlargement of the listening zone with appropriate localization of the Sound sources when applying the invention. With the outside hatched hexagon is the possibility of further Enlargement of the listening zone by means of an additional derivative Playback channels shown schematically.

Another significant advantage when using the invention results from the not rigidly attached to the standard arrangement bound placement of the speakers in the individual Playback area.

To also the advantageous reproduction of program contributions enable that according to one of the matrix methods, e.g. by means of of the Dolby stereo surround system, is transmitted after the decoder usually used (e.g. Dolby Pro Logic Surround decoder) a device according to the described Procedures required - depending on your wishes and ideas of the user - both a five- or 5-plus-1-channel offer Program as well as other single or multi-channel programs can process.

• der Eingangsmatrix EM mit den davorliegenden Eingangsstufen E,
• den Funktionseinheiten FD zur mehrkanaligen, unabhängigen Laufzeit-, Pegel- und ggf. erforderlichen Phasenkorrektur,
• den Summierstufen SE und
• der Ausgangsmatrix AM.

The loudspeaker arrangement available for multichannel playback and set up in a room in compliance with the standard and the available possibilities is supplemented by a device which, after a radio and / or TV receiver or a playback device for multichannel sound recordings, and before the individual power levels Loudspeaker must be switched.
According to FIG. 2 it consists of:

• the input matrix EM with the input stages E in front of it,
• the functional units FD for multi-channel, independent runtime, level and possibly necessary phase correction,
• the summation stages SE and
• the output matrix AM.

Thus the inputs of the input stages (1-n) are with the outputs a multi-channel receiver or other one or multi-channel program sources connected. The outputs of this Input stages are with the inputs of the input matrix EM connected. This distributes the existing input signals over the connections to the functional units FD, so that each FD receives n-1 of the available input signals. The (n-1) outputs of each FD are connected to the inputs of a summing stage SE connected. Via a direct connection between the input matrix EM and each summing stage SE each arrive an unprocessed input signal in each summing stage, so that in each SE a sum signal from the n input signals can be formed.

These sum signals differ in that in each Sum signal differently processed signals and an unprocessed Signal from the number of inputs available Signals are present.

The outputs of the summing stages SE - those on the output side Possibility of controllable level control included - are connected to the output matrix AM so that they are connected to the existing connected playback channels, d. H. With are connected to the inputs of the power amplifiers and via the output matrix is assigned to the corresponding playback channels become.

When considering the multi-channel playback of a Programs with fewer than 5 signals can supplement FIG. 3 of this functional complex in front of the input matrix EM a conversion matrix KM, which the existing ones Input signals distributed to the input matrix EM.

In this case, the outputs of the input stages E are included connected to the inputs of the conversion matrix KM and their Outputs with the corresponding inputs of the input matrix EM.

Unless a separate bass channel is not in the program signal is included, can be used to generate a separate bass channel to the outputs of input stages E a filter unit FE-1 can be switched. In this, as also known, via a low-pass circuit from the existing input signals, preferably the three front signals, the low-frequency signal components filtered out, summed and assigned its own bass channel.

To adapt the speakers to the existing room conditions can - as with the stereo playback in high quality home display devices practiced - for that Playback channels another filter module FE-2 of the output matrix are connected downstream (Fig. 4).

To acoustically optimize this display arrangement to the existing room conditions, locations of the speakers and the desired listening zone is one for this special device Assign input unit EA. This enables the entry the locations of the speakers, their parameters, the existing ones Room conditions and the desired listener positions, the further the possibility of correcting and adjusting the conditions between direct information and desired room information (R / D) depending on the program material.

This input arrangement EA is in control with the individual Assemblies of the entire device connected and controls the variably adjustable parameters of the individual modules. It calculates parameters independently on the basis of the entered room and location parameters and assigns them to the corresponding assemblies.

For visual control of the entered parameters is as Completion of the input arrangement a display on a display intended.

If larger hearing zones are supplied, additional ones will be added Functional units FD inserted, whose inputs with all Outputs of the input matrix EM are connected and thus a sum signal from all - but treated differently - Input signals for each additional playback channel 1 to m, each with additional distributed speakers is connected, is formed (Fig. 4).

This allowable extension of the device - any input signal, the signal not to be processed is also transmitted an FD to the summing stage - simplifies the circuitry Solution of this device, as shown in Fig. 6.

The signal flow for a 5-channel program can be explained as follows:
The signals pass from the source (transmission channel, multi-channel recording, etc.) to the input stages E of this special device. They are distributed to the existing functional units FD by means of the input matrix in such a way that four of these 5 available input signals are assigned to each FD, so that one signal in each FD is not subjected to a parameter correction. (In the first FD, the first signal is switched unprocessed to the subsequent summing stage SE, in the second FD the second, etc.).

In the downstream summing stage SE, the four are related Level, duration and phase treated differently Signals and the once untreated signal again summed up and corrected together in level. At the exit of the Output matrix AM, these sum signals are the existing ones Playback channels and the speakers connected to them with their performance levels according to their function definition (Front speaker surround speakers).

In a permissible extension of the device, the functional units can FD can be expanded to include a parameter change allow for all input channels, so that for each playback channel a sum of all existing and treated input signals arises (Fig. 6)

If a filter device FE-1 is connected downstream of the input stages, so are the low frequency parts of each unprocessed source signals filtered out, summed in the SE and assigned a separate bass channel that has a Level correction unit a special woofer supplied with the appropriate power unit.

The placement of the not always according to the standard Speakers and the optimal one that can hardly be kept in practice Arrangement of the handset and the spatial home conditions require in most applications, one for each Frequency response correction adapted to the room and the desired listening zone the loudspeaker and possibly a runtime correction the playback channels depending on their location. The latter can be done in the FD.

For a required spatial adjustment of the frequency response, you can 4 and 5 - the signals at room correction filter modules FE-2 between the output matrix AM and the Inputs of the power amplifiers of the playback channels switched become.

These room correction filters allow the timbre of the entire playback arrangement, through changes in each Playback channels, the respective room and the performances of the user by entering correction values adapt.

The deviations from a standard list are due to the Entry of the location parameters in the input unit can be corrected. By entering additional parameters such as speaker data, Listening zone or listener positions etc. can both Volume ratios corrected as well as listening conditions outside of an optimal listening position, especially in the preferred area (preferred listener position) of the user, optimized become.

The ratio between direct component and surround component can also depending on the program material by entering appropriate correction values in the existing input unit changed, saved and assigned to the current program be retrieved again.

The use of this device also for the playback of Program material with less than five audio channels is through the conversion matrix upstream of the input matrix EM KM enables.

Claims (9)

1. Method for multi-channel sound reproduction in which the sound signals are recorded in multi-channel and source-oriented manner and in which, prior to being emitted, said multi-channel sound signals are processed by matrixing and summation and are distributed onto front and surround playback channels and optionally also onto a sub-bass channel, characterized in that, after distribution of the sound signals onto at least three front and two surround playback channels, sub-signals are branched off from each of said sound signals and the branched-off sub-signals, differently processed according to their directional assignment, are each summated with an increased propagation delay time, reduced level and at least partially changed phase position to one of the five or more unprocessed sound signals, such that each summation signal contains differently processed sub-signals and an unprocessed sound signal and the directional assignment of the summation signals, including after further similar divisions and summations, to the channels of the three front and two surround playback loudspeakers distributed in the room, and, where applicable, further playback loudspeakers, is effected according to the orientations of the unprocessed sound signals.
2. Method according to claim 1, characterized in that the further playback loudspeakers additionally distributed in the room, preferably for surround signals, are supplied with further signals each formed as a sum consisting of the sub-signals - split off from the unprocessed sound signals and differently processed in propagation delay time, level and phase - and an unprocessed sound signal, and in that the changes of amplitude and propagation delay time are selected according to the distance of each further additional playback loudspeaker from the location of the first three front and two surround loudspeakers and the corresponding supply area of the aforementioned additional surround loudspeakers.
3. Method according to claim 1, characterized in that there is also a summation of sub-signals exclusively thus branched off from the sound signals and processed, in which summation the summation signal for each playback channel contains a processed sub-signal from each sound signal present at the input.
4. Device for multi-channel sound reproduction with a plurality of input connections for at least three front and two surround playback channels in which the inputs are each connected through an input stage to the corresponding input connections of an input matrix (EM), characterized in that the outputs of the input matrix (EM) are connected on the one hand to the same number of input connections of a functional unit (FD) for the in each case separate different correction of the supplied signals with regard to propagation delay time, level and, where applicable, phase for each output of said functional unit (FD) and on the other hand are connected to the first inputs of a summation unit (SE) to the second and/or further inputs of which are connected the outputs of the functional unit (FD), and in that the summation signals each formed from an unchanged input signal at the input stage (E) with differently processed signals of other input signals are connected according to the assignment of the unprocessed input signals to the outputs of an output matrix (AM) for the at least three front and two surround playback channels and, where applicable, further playback loudspeakers.
5. Device according to claim 4, characterized in that connected ahead of the input matrix (EM) is a further conversion matrix (KM) which distributes the available sound signals of recordings or broadcasts with fewer than five sound channels, particularly from mono, 2-, 3-, 4-, 5/2-channel stereo surround methods, onto at least five input stages of the input matrix (EM).
6. Device according to claim 4, characterized in that connected ahead of the input matrix (EM) in the absence of a separate sub-bass broadcast and/or recording channel is a multi-channel filter unit which contains lowpass circuits (TP) and a summation stage and which filters out and summates the extra-low-frequency components of the available sound channels and assigns same to a separate sub-bass playback channel to the output of which are connected extra-low-frequency loudspeakers and/or subwoofers.
7. Device according to claim 4, characterized in that the functional unit (FD) is provided with an input arrangement (EA) for the input of the room conditions of the playback arrangement, according to the loudspeaker positions, and of the desired parameters, with regard to the loudspeaker ratios of front and surround loudspeakers.
8. Device according to claim 7, characterized in that the input arrangement (EA) is associated with a display which shows the inputs and the parameters which are to be changed, with regard to propagation delay time correction, level correction, degree-of-correlation correction, etc.
9. Device according to claim 7, characterized in that the input arrangement (EA) is provided for further parameters of the sound signals which are to be influenced and is thereby connected to the units (KM, FE, SE, EM) which influence the sound signal paths through their processing elements including the required parameter values from the inputted room parameters and personalized definitions.

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