EP1653777A2 - Method and circuit to generate reverberation for a sound signal - Google Patents

Abstract

The response circuit includes a reverberator (RV) for producing reverberation signals (RL,RR), and a mixer ((A2) for combining the sound signals (L,R) with the reverberation signals. The reverberator has input ports for receiving reverberator input signals (GL,GR) which are used as basis for generating the reverberation signals. A signal source (I) is provided to produce the sound signals comprising of several components (L,R,LS,RS,C). An independent claim is included for the response generation method.

Description

The invention relates to a circuit for generating reverberation for a sound signal with the preamble features of claim 1 and to a method for generating reverberation for a sound signal.

Commonly known circuits for generating reverberation for a sound signal with a signal source for providing a sound signal, a reverberator for providing a Reverberationssignals and a mixer for combining the audio signal or a component of the audio signal and the Reverberationssignals. Such circuits or corresponding methods in the field of radios, television applications and electronic music devices are used. On a sound signal, stereo sound, if necessary, 3D sound signal or a so-called surround sound signal, a reverberation is artificially mixed, so that a spatial sound effect is created and the listener of the sound signal hears a natural sound signal. The reverberation creates the impression of a sound signal which, after being transmitted through a sound source, has not only passed over the direct path to the listener or receiver, but has additionally run on walls of a room and the like at later times to the listener. The listener thus receives a mixed or superimposed signal.

For television applications, different numbers of output channels are provided depending on the price category of the respective television set. Simple TV applications are a mono output for outputting only a mono audio signal. Common TV applications provide a stereo output for outputting a stereo audio signal, ie a sound signal with two independent signal components. More complex Television applications offer a variety of output channels, in particular three output channels in the case of a so-called 3D stereo audio signal. Five or for example six output channels for individual components of the audio signal are known, for example, by so-called 5.1 systems in which audio signal components for loudspeakers are provided left, right, centrally in front of a listener and in the surround (surround) left, right and optionally for a so-called subwoofer ,

Conventional audio signal processing processors, in particular so-called hi-fi processors, are each designed for a certain number of loudspeakers for which the reverberation is optimized. In television, however, most devices still have two or three speakers, with a corresponding processor or chip being used to provide the sound signal. It is thus disadvantageous that individual processors for the different applications are to be provided in each case and accordingly a second processor is to be used for television sets with two loudspeakers than for a television set with three loudspeakers, if in each case an optimized reverberation should be available. The same applies to an even larger number of output channels for even more speakers.

Generally known from US 5,917,917 is a so-called wave table synthesizer for applications in an electronic musical instrument. An artificial reverberation is mixed in by means of a digital reverberation simulator to a sound signal generated synthetically by the musical instrument. From a delay line or delay line (delay line), a signal is decoupled from the Hall structure by means of a separate tap and added or subtracted with an added-up feedback signal. This solution produces a signal that fluctuates too much in the stereo panorama because certain signal frequencies on a channel can be completely extinguished. The description of the applications is limited to stereo audio signals.

M. R. Schröder, Natural-Sounding Artificial Reverberation, 1962 describes a mono-Hall structure in which a pseudo-stereo effect is produced at the output by two all-passes with different weighting factors. Disadvantage of this structure is that it sounds quite unnatural or tinny due to the all-passes used. In addition, the density of the reflections for a natural sound impression is not sufficient.

Bill Gardner, Realtime Multichannel Room Simulator, J. Acoust. Soc. Am., 92 (4), pp. 2395, 1992, describes a multichannel room simulation with separate signal paths for each individual output channel, which means an enormous amount of computation and is unsuitable for applications in the television sector.

The object of the invention is therefore to improve a method and a circuit for generating reverberation for a sound signal, in particular with regard to applications in television sets.

This object is achieved by a circuit for generating reverberation for a sound signal having the features of patent claim 1 or by a method for generating reverberation for a sound signal having the features of patent claim 8.

Accordingly, a circuit for generating reverberation for a sound signal with a signal source for providing a sound signal with at least one component, a reverberator for providing at least one reverberation signal and a mixer arrangement for combining the audio signal or a component of the audio signal and the reverberation signal, wherein the reverberator an input for inputting the sound signal or one generated from the sound signal Reverberator input signal as a basis for the generation of the Reverberationssignals.

According to the method, according to the invention, a method for generating reverberation for a tone signal in which a tone signal with at least one component is provided by a signal source, at least one reverberation signal is provided and the tone signal and the reverberation signal are mixed together, the tone signal and the reverberation signal being provided for generating the reverberation signal a signal generated from the sound signal is used.

Advantageous embodiments are the subject of dependent claims.

In particular, a circuit with the signal source providing a tone signal with a plurality of components and with a virtualizer for mixing together the signals output by the mixer arrangement to a smaller number of components of a tone signal to be output is preferred.

In particular, a circuit with a mono-Hall structure in the reverberator for outputting delayed signals on delay lines is preferred.

In particular, a circuit having a respective first and a second multiplier on the delay lines is preferred for multiplying by a weighting factor and for providing in each case a left-side and a right-side component of the reverberation signal.

Particularly preferred is a circuit of a second group of delay lines for providing a further reverberation signal for mixing together with at least one other component, in particular environmental component, as a left and a right component of the audio signal.

In particular, a circuit with a tap for additionally providing the reverberation signal as a further reverberation signal for mixing together with at least one other component, in particular an environmental component as a left and a right component of the audio signal, is preferred.

In particular, a circuit with a delay device is preferred for delaying the further reverberation signal relative to the reverberation signal.

In particular, a method is preferred in which the signal mixed together from the audio signal and the reverberation signal is provided from a multiplicity of audio signal components with a corresponding multiplicity of signal components and mixed together after mixing together to form a sound signal having a smaller number of components.

In particular, a method is preferred in which the reverberation signal is provided with mono signal processing with the outputting of time-delayed signals, wherein the time-delayed signals are weighted with weighting factors for providing a first and a second component of the reverberation signal.

In particular, a method is preferred in which a further reverberation signal is provided for mixing together with at least one other component, in particular environmental component, as a left and a right component of the audio signal.

Such a circuit or method provides an opportunity for all possible speaker configurations to generate reverberation. For this purpose, between a signal input, in particular multi-channel signal input or a multi-channel decoder, and a signal output, in particular a virtualizer as a signal output, a function or a Integrated circuit arrangement, which generates reverberation and allows the speaker through the virtualizer scalable speaker configurations. Advantageously, a multi-channel input signal is used as a direct signal for the reverberation, so that a combination of direct signals as an immediate signal of the input or the multi-channel audio signal source is carried out with the reverberation signals. Reverberation is anchored in the system in such a way that a wide variety of applications with ultimately one and the same method or the same circuit can be used in the most diverse configurations of the audio signal output. Both 5.1 applications as well as applications with two or three speakers will be able to generate a high-quality reverberation.

Fig. 1

eine beispielhafte Schaltungsanordnung zur Nachhallgenerierung bei einer Multikanal-Ausgangskonfiguration mit Surround-Kanälen mit separaten Abgriffen am Separator;

Fig. 2

eine Schaltungsanordnung gemäß Fig. 1 mit jedoch einer Stereo-Ausgangskonfiguration;

Fig. 3

eine Schaltungsanordnung mit einer Multikanal-Ausgangskonfiguration und Surround-Kanälen ohne separate Abgriffe für die Surround-Kanäle; und

Fig. 4

eine Schaltungsanordnung gemäß Fig. 3 mit einer Stereo-Ausgangskonfiguration.

An embodiment and variants thereof are explained below with reference to the drawing. Show it:

Fig. 1

an exemplary circuit for reverberation generation in a multi-channel output configuration with surround channels with separate taps on the separator;

Fig. 2

a circuit arrangement of Figure 1 but with a stereo output configuration.

Fig. 3

a circuit arrangement with a multi-channel output configuration and surround channels without separate taps for the surround channels; and

Fig. 4

a circuit arrangement according to FIG. 3 with a stereo output configuration.

A basic idea is to provide a tone signal input, in particular a multi-channel source or a multi-channel decoder, for providing a direct signal for generating reverberation and subsequently adding the reverberation to, in particular, all channels of the multi-channel signal in a first step. This produces a 5.1-tone signal with reverberation, which can subsequently be provided in this form at an output or can be mixed together again by means of a virtualizer on two or three channels with the aid of a so-called Head Transfer Function (Kopfübertragungsfunktion). By means of the so-called head transfer function, a signal is generated which generates the acoustic impression of a spatial signal in the listener of a correspondingly emitted sound signal. This results in a surprisingly good spatial reverberation even in the case of only two or three speakers, while in the case of a direct 5.1 application, the surround channels (see page 13). As a result, the reverberation generation as such can be implemented identically for all possible loudspeaker configurations by a single method or a single circuit.

FIG. 1 shows a first exemplary reverberation circuit for scalable loudspeaker configuration applications. In addition to such a circuit implementation is also a procedural implementation in accordance with suitable microprocessors and the like can be implemented.

At a sound signal input I, a sound signal is provided. The audio signal input I can be an input for inputting an external audio signal. A multi-channel source, in particular a multichannel decoder, is preferred as the audio signal input I. The audio signal can thus in the simplest case be a mono signal or a stereo signal, each having a component for a left and a right audio signal channel L, R. Preferably, however, a multi-component audio signal is provided by the audio input I, in particular a so-called surround sound signal with five components for the known channels left L, right R, left surround LS (left environment), right surround RS and Center C. It is also possible to provide a so-called 5.1-tone signal in addition to a so-called subwoofer.

A conversion to systems with even more audio signal components than other channels is possible.

The sound signal input I also provides a total signal on a total signal bus GB. The overall sound signal preferably consists of two components GL, GR for a left-side overall sound signal channel and a right-side overall sound signal channel. The provision is effected, for example, by adding up the respective components for left-sided or right-sided channels in the sound signal input I or in a correspondingly suitable circuit arrangement in the sound signal input I. The overall sound signal GL, GR is fed to a reverberator RV.

The Reverberator RV forms a delay line, which is referred to as Delay Line. The input into the reverberator RV components GL, GR of the total sound signal are forwarded delayed in time between a plurality of successive taps of the delay line, so that at the individual taps each time delayed signals relative to the present at the audio input I input signal L, R, LS, RS, C are present. The reverberator RV outputs signals delayed in time corresponding to delay lines T1, T2, T3. If different delays are to be provided for the signal components L, R of the left and the right channel and signal components LS, RS of the surrounding channels, a corresponding delay arrangement is provided with its own delay lines T1 *, T2 *, T3 *.

The delayed signal provided on the first delay line T1 is supplied to two multipliers M. In the two multipliers, a multiplication is carried out, each with a correspondingly applied to the multipliers M weighting factor g11, g1r for a left-side and a right-side delay component. The two weighting factors g1l, g1r are usually between 0 and 1 and amplify or weaken the signal applied to the delay line T1 corresponding to a reflection spatial direction from the left or right from the perspective of a listener. The output signals of the multipliers M are supplied to left and right components RL, RR of a reverberation bus RB to provide a reverberation signal. In the same manner, the delayed sound signals on the further delay lines T2, T3 are also supplied in accordance with associated multipliers M for multiplication with corresponding weighting factors g2l, g2r, g3l, g3r. The output signals of the multipliers M are also added to the left and right components RL, RR of the Reverberationsbusses RB.

In the case of dedicated delay lines T1 *, T2 *, T3 * for environmental components, these further delay lines T1 *, T2 *, T3 * are supplied to a corresponding group of multipliers for application according to desired delay factors g1ls, g1rs,. The output signals of the respective multipliers M * are supplied to a left and a right component RLS, RRS, respectively, of a corresponding ambient reverberation bus RBS.

The reverberation signal present on the reverberation bus RB or on the ambient reverberation bus RBS or its components RR, RL, RRS, RLS are fed to a further group of multipliers M2 or M2 *. By means of this further group of multipliers M2, M2 *, a desired amplification or attenuation of the reverberation signal takes place on the respective bus RB, RBS.

Instead of buses, of course, conventional lines can be provided as individual lines. In addition to a transmission of analog signals via such lines and a transmission via digital lines or buses with a transmission of the components of multiple channels on a single line in a staggered sequence and the like is possible.

The reverberation signals on the Reverberationsbus RB are added by means of a further arrangement of adders A2 as a mixer arrangement of the left and the right component L, R of the input signal and output via an output 0 to a further Tonsignalverarbeitung or a corresponding speaker as Ausgangsstonsignal. Accordingly, the signals of the ambient reverberation bus RBS are provided by means of further adders A2 * to the ambient components LS, RS of the input signal or of the ambient signal provided by the audio signal input I for output via the output 0.

In the illustrated embodiment, no reverberation signal is added to the central component C of the audio signal input I. Optionally, however, this component C can also be added with reverberation signals. This can be, for example, separately generated reverberation signals or a combination or summation of the remaining reverberation signals.

In the description of the further exemplary embodiments with reference to FIGS. 2 to 4, only components or method steps which differ from the embodiment according to FIG. 1 are described below. Otherwise, reference is made to the comments on FIG. 1.

While FIG. 1 illustrates reverberation generation in a multichannel output configuration with separate taps of the delay line for the surroud channels or components, FIG. 2 illustrates reverberation generation in a stereo output configuration in conjunction with separate taps for surround channels At the output 0 to provide a stereo signal with only one virtual right and a virtual left component VR, LV, the output signals of the audio signal input for the individual components L, R, LS, RS, C are fed to a so-called virtualizer V. The left and right component L, R is previously added according to the embodiments of FIG. 1 again a corresponding Reverberationssignal. Likewise, the left and the right environmental component LS, RS are again added a corresponding ambient reverberation signal before being supplied to the virtualizer V. In virtualizer V, in a manner known per se, the virtual right and the virtual left signal are generated in such a way that a virtual spatial sound resembles that of a surround sound signal in a listener. In the case of a 3D stereo audio signal, the sound signal of the central component C is output unchanged or, if appropriate, also adapted as a third component.

3 shows an embodiment in which for the left and right components to be output on the one hand and left and right ambient components on the other hand, not two independent reverberation signals RR, RL, RRS, RLS as in FIG. 1 but only a single reverberation signal RR, RL is provided. This single reverberation signal RR, RL is added to the left and right components L, R after a corresponding multiplication in the second group of the multipliers M2. In addition, this reverberation signal or its components RR, RL is added after amplification or attenuation with corresponding multipliers M2 * in addition to the left or right environmental component LS, RS by means of the second group of adders A2 *. Optionally, the reverberation signal RR, RL, which is added to the environmental components LS, RS, be previously delayed by means of a delay device D. The signals thus generated are in turn fed directly to the output 0.

FIG. 4 shows an embodiment in the manner of a combination of the embodiments according to FIGS. 2 and 3. According to FIG. 3 again only one single reverberation signal is provided with two components RL, RR, which the left and right components L, R and, if necessary Time-delayed, the left and the right environmental component LS, RS added accordingly becomes. To provide a stereo output configuration, the sound signals thus provided are in turn supplied to a virtualizer V according to the embodiments of FIG.

By using a Tonsignalingangs I in particular, a multi-channel source, such as a multi-channel decoder and the provision of a direct signal on the Gesamtsignalbus GB for the generation of reverberation and the subsequent adding up the reverberation on preferably all channels of the original multi-channel audio signal arises in one first method step, a multi-channel audio signal, which can be mixed together in a subsequent step by a virtualizer V back to two or three channels using the Kopfübertragungsfunktion (Head Transfer Function). This results in an amazing spatial reverberation even in the case of two or three loudspeakers, while in the case of e.g. a 5.1 application the surround channels. The reverberation generation is correspondingly advantageous for all speaker configurations at the output O identical.

The surround channels "only" provide for the impression of space because the sound level of the surround channels is lower compared to the sound level of the front channels. As a result, the subtle reverb-mixed reverb signal appears in a 5.1 system primarily in the surround channels, although the reverb signal is mixed in to all channels.

For reasons of computing time, a mono-Hall structure is advantageously implemented by means of the reverberator RV, at which output signals are coupled out at different points of the delay path. These taps or delay lines T1, T2, ... are multiplied by different weighting factors g1l, g1r, g2l, g2r,... For the left and right channels and the left and right components L, R, and then added thereto. Thus, for each tap of the delay line a position in the stereo panorama can be selected, the strength of the stereo effect on the coefficients of the multipliers M can be controlled. Depending on the position of the listener within a virtual room, reflections of walls in strength and direction can be simulated.

After the tone signals of the individual delay lines T1, T2,... Or taps of the delay line have been multiplied and added up with weighting factors g1l, g1r,..., A reverberation signal for the left and the right component L, R stands as the reverberation signal RL. RR, which is acted upon by a further factor for the overall volume of the reverberation with respect to the direct signal in the further multipliers M2.

For the surrounding channels or environmental components LS, RS of the sound signal provided by the sound signal input I, either separate taps from the or a further delay line can be provided or the reverberation signals or Reverberationssignale the left or right component RL, RR for the left and the right ambient channel be used. Optionally, a delay may be used for the reverberation signals for the environmental components. Own taps on the delay line lead to uncorrelated signals between front (front) and rear (surround) speakers, resulting in a better spatial impression. (Front / Surround with bad correlation is advantageous in the case of a Hall signal)

The described embodiments are not limited to a 5.1 decoder as a sound signal input I. Use is also possible in conjunction with a mono input signal or a stereo input signal or other multi-channel input signal. In particular, instead of a multichannel decoder, a signal input I fed from the outside can also be present as a multichannel audio input signal fed in from the outside.

The center channel for the central component C does not necessarily have to be led past the reverberation generation, as in the described embodiments. Also possible is an addition of an independent reverberation signal or an addition of an existing reverberation signal or an existing reverberation signal.

Claims (11)

Circuit for generating reverberation for a sound signal with a signal source (I) for providing a sound signal having at least one component (L, R, LS, LS, RS, C), a reverberator (RV) for providing at least one reverberation signal (RL, RR) and a mixer arrangement (A2) for combining the audio signal or a component (L, R) of the audio signal and the reverberation signal (RL, RR), characterized in that - The Reverberator (RV) has an input for inputting the sound signal or a generated from the sound signal Reverberator input signal (GL, GR) as the basis for the generation of the Reverberationssignals (RL, RR). Circuit according to claim 1 - A sound signal with a plurality of components (L, R, LS, LS, RS, C) providing the signal source (I) and a virtualizer (V) for mixing together the signals output by the mixer arrangement (A2, A2 *) to a smaller number of components (VL, VR) of a sound signal to be output. A circuit according to claim 1 or 2 having a mono-Hall structure in the Reverberator (RV) for outputting delayed signals on delay lines (T1, T2, T3). A circuit according to claim 3, including first and second multipliers (M) on the delay lines (T1, T2, T3) for multiplying by a weighting factor (g1l, g1r, g1l, g2r, ...) and providing left and right ones, respectively a right-sided component (RL, RR) of the reverberation signal. A circuit according to claim 3 or 4 including a second group of delay lines (T1 *, T2 *, T3 *) for providing a further reverberation signal (RLS, RRS) for mixing together with at least one other component, in particular environmental component (LS, RS), as a left and a right component (L, R) of the audio signal. A circuit according to claim 4, comprising a tap for additionally providing the reverberation signal as a further reverberation signal (RLS, RRS) for mixing together with at least one other component, in particular environmental component (LS, RS), as left and right components (L, R) of the audio signal , A circuit according to claim 5 or 6, comprising delay means (D) for delaying the further reverberation signal relative to the reverberation signal. A method for generating reverberation for a sound signal, wherein a signal from a signal source (I) is provided with at least one component (L, R, LS, LS, RS, C), - At least one Reverberationssignal (RL, RR) is provided and the sound signal and the reverberation signal are mixed together, characterized in that - To provide the Reverberationssignals the sound signal or a signal generated from the sound signal (GL, GR) is used. The method of claim 8, wherein the signal mixed together from the audio signal and the reverberation signal is provided from a plurality of audio signal components having a corresponding plurality of signal components and mixed together after mixing together to form a lower number of components (VL, VR, C) sound signal becomes. A method according to claim 8 or 9, wherein the reverberation signal is provided with mono signal processing with the output of time delayed signals, the time delayed signals being weighted with weighting factors to provide a first and a second component (RL, RR) of the reverberation signal. Method according to one of claims 8 to 10, wherein a further Reverberationssignal for mixing together with at least one other component, in particular environmental component (LS, RS), as a left and a right component (L, R) of the audio signal is provided.

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