JPH05165485A - Reverberation adding device - Google Patents

Abstract

PURPOSE:To simplify configuration by serially connecting plural feed forward filters (FIR Filters) and convolving the representative pattern of an energy change into one filter at least. CONSTITUTION:Since FIR filters 1-4 are serially connected and the representative pattern of the energy change is convolved into one of them at least, it is enough only to execute calculation nXA<1/n> times when defining the number of required echo as A by serially connecting (n) steps of FIR filters and therefore, the number of times for calculation can be reduced. Further, in the case of forming right and left stereo reverberation, the FIR filter to be convolved this pattern can be made common. On the other hand, when forming the reverberation of right and left sounds, the FIR filter to be convolved the pattern is divided into the FIR filters in preceding and following steps, the preceding step FIR filter is common concerning the pattern, the pattern of the following step FIR filter is made different and therefore, the spreading feeling of the reverberation sound is further improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reverberation adding device for simulating the feeling of presence and expanse of a music venue in a room of a general household or in a vehicle. In particular, the present invention aims to simplify the configuration of the reverberation adding device.

[0002]

2. Description of the Related Art Conventionally, as a technique in such a field, there is one described in Japanese Patent Laid-Open No. 60-51894. In this publication, input signal data is sequentially taken in at a fixed sampling cycle, and a plurality of delayed input signal data corresponding to respective delay times of impulse response of reverberation characteristics are time-divided for a plurality of types of impulse responses at each sampling cycle. Then, the gain data of each impulse response is applied to each extracted delayed input signal data, the convolution operation is performed for each impulse response for each sampling cycle, and the multiple calculation results obtained for each sampling cycle are used for each reverberation signal. The reverberation adding device which outputs as is shown.

A feed-forward type (FIR Filter) type reverberation device is used, and when a reverberation effect for a long time is to be obtained, a feedback type comb filter (Comb F
ilter) is used in combination.

[0004]

However, in the conventional reverberation adding device, when trying to form a reverberation effect for a long time, the recursive comb filter (IIR Filter) has a relatively small number of calculation steps and the reverberation is performed at a low cost. Although it is possible to increase the density, it is difficult to remove the periodicity of the sound, and it is easy to generate unnatural sounds.On the other hand, a non-cyclic (FIR Filter) filter has no periodicity in the sound, but when the reverberation density is increased There is a problem that the number of calculation steps becomes large and the cost becomes high.

In view of the above problems, it is an object of the present invention to provide a reverberation adding device which can obtain a natural reverberation sound having a relatively low cost and no periodicity.

[0006]

In order to solve the above problems, the present invention delays a digital signal, applies a coefficient to each delayed signal to adjust the amplitude, and adjusts the amplitudes. F that adds and outputs signals to form reverberant sound
In the reverberation adding device including an IR filter, the FIR
A plurality of filters are connected in series, and at least one of them is convoluted with a pattern representative of energy change.
Further, a FIR filter for convolving a pattern representative of energy changes is commonly used in stereo reverberation of left and right sounds. In addition, F which folds a pattern representative of energy change in the formation of reverberant sounds of stereo left and right sounds
The IR filter is divided into a front-stage and a rear-stage FIR filter,
The pattern of the front stage FIR filter is common, and the pattern of the rear stage FIR filter is different.

[0007]

According to the reverberation applying apparatus of the present invention, a plurality of the FIR filters are connected in series, and at least one of them is convolved with a pattern representative of the energy change. Assuming that the reverberations are connected in series, if A reverberations are required, A times of multiplication has been conventionally required, but nxA ^{1 / n} times of calculations can be performed, and the number of calculations can be significantly reduced. Low cost can be achieved. Since it is composed of an FIR filter, there is an advantage that there is no periodicity unlike the conventional cyclic (IIR) type. Further, it is possible to use a common FIR filter for convolving a pattern representative of energy changes in the formation of reverberant sounds of stereo left and right sounds, and it is possible to reduce the number of FIR filters and further reduce the cost. Further, the FIR filter for convolving the pattern representative of the energy change in the formation of the reverberation of the stereo left and right sounds is divided into the FIR filters of the front stage and the rear stage, the pattern of the front stage FIR filter is made common, and the pattern of the rear stage FIR filter is formed. By making them different, the spread of reverberant sound is further improved.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a reverberation applying apparatus according to a first embodiment of the present invention. The reverberation adding apparatus shown in the figure receives a stereo Lch digital signal and delays it for each sampling cycle, for example, a multiplier 12 connected to an arbitrary output of the delayer 11, and an output of the multiplier 12. A first FIR filter 1 for Lch for convolving m1 reverberation patterns, and an adder 13 for adding
The output signal from the adder 13 is input, for example, a delay device 21 that delays at each sampling cycle, a multiplier 22 connected to an arbitrary output of the delay device 21, and an output of the multiplier 22 are added to obtain an Lch output signal. And an adder 23 to be formed,
A second FIR filter 2 for Lch that folds a pattern representing n1 energy changes, and a stereo Rch
Of the delay unit 31 for inputting the digital signal of the above, for example, for delaying each sampling period, a multiplier 32 connected to an arbitrary output of the delay unit 31, and an adder 33 for adding the outputs of the multiplier 32, m2 It is connected to the first FIR filter 3 for Rch for convolving the reverberation pattern of the book, a delay device 41 for inputting the output signal from the adder 33 and delaying it at every sampling cycle, and an arbitrary output of the delay device 41. 2nd Rch for convolving a pattern representative of n2 energy changes, and an adder 43 for adding the outputs of the multiplier 42 and the output of the multiplier 42 to form an Rch output signal.
FIR filter 4 of. The delay devices 11, 21, 3
1 and 41 may be configured by RAM (Radom Access Memory) (the same applies hereinafter).

According to this embodiment, the first F for Lch is used.
If the number of multipliers 12 and 22 forming the reverberation output of the IR filter 1 and the second FIR filter 2 for Lch is n1≈m1, for example, when one impulse signal is input to the delay device 11, the reverberation output is 2. n1 ² this is formed by n1 multipliers. In a conventional FIR filter, n
Since 1 ² multipliers are required, 2 · n1 / n1 ² =
The multiplier will be reduced by the ratio of 2 / n1. Thus, since the FIR filter has no periodicity, the desired cost reduction can be realized. The same applies to the first FIR filter 3 for Rch and the second FIR filter 4 for Rch.

Although the above description has been made with respect to the cascade connection of two stages of FIR filters, generally, it may be constituted by multiple stages n, and in the case of n1, approximately n · n1 / n1.
It decreases to the ratio of ⁿ = n / n1 ^n-1 . Specifically, if it is attempted to form a reverberation sound at 50 KHz for 2 seconds, the conventional
Since 0x2 multipliers are required, the DSP (Digita
(Signal Processor) The scale becomes enormous, but even in the case of two stages, it becomes 2 × (50000 × 2) ^1/2 ≈600, which can be significantly reduced.

FIG. 2 is a diagram for explaining setting of coefficients of the multiplier shown in FIG. The Lch side will be representatively described with reference to FIG. As shown in this figure (a), in order to simulate the reverberation characteristic measured at the music venue, the actual data is divided into two stages, the pattern of each section representing the energy change and the reverberation pattern in each section. .. As shown in FIG. 6B, the multiplication coefficient set in the multiplier 12 is composed of m1 reverberation patterns in which the intervals in each section are t1, t2, ..., Tm1. This total interval is, for example, 200 msec, and Lc
First FIR filter 1 for h and first FIR filter for Rch
, Tm1 of the multipliers of the filter 3 are shifted from each other by, for example, about 0.5 msec or different levels are provided to adjust the arrival direction of the reverberation sound to form a stereo effect.

As shown in FIG. 1C, the multiplication coefficient set in the multiplier 22 is composed of n1 patterns in which the intervals of each section representing the energy change are T1, T2, ..., Tn1. To be done. As shown in this figure (d), the output reverberation sound is formed by combining the reverberation sounds obtained in this figure (a) and (b). Therefore, by making the intervals in each stage different, the occurrence of periodicity in the comb filter is prevented.

FIG. 3 is a diagram for explaining the setting of the multiplication coefficient when the reverberation characteristic is discrete. As shown in FIG. 6A, the reverberation sound may change discretely instead of changing continuously. Even in such a case, as shown in this figure (b), the gradient of the reverberation pattern is made steep, and as shown in this figure (c), the interval of the pattern of each section that represents the energy change is made small and the reverberation is reduced. By making the patterns overlap, the output signal can be simulated as the reverberant sound shown in this figure (a), as shown in this figure (d). In this case, there is an advantage that the density of reverberation sound increases. In this way, the reverberant sound can be formed in the same manner as in the conventional case even if it is divided into a plurality of stages.

FIG. 4 is a diagram showing a reverberation adding apparatus according to the second embodiment of the present invention. The reverberation adding apparatus shown in this figure is a multiplier 201 for inputting a stereo Lch digital signal and an Rch digital signal and adjusting the respective levels.
And 202, an adder 203 that adds the outputs of the multipliers 201 and 202, a delay device 51 that delays the output signal of the adder 203 for each sampling cycle, and an arbitrary output of the delay device 51. A first FIR filter 5 for convolving m1 reverberation patterns, and an adder 53 for adding the outputs of the multiplier 52.
And a delay device 61 for delaying the output signal of the adder 53 for each sampling cycle, a multiplier 62 connected to an arbitrary output of the delay device 61, and an adder 63 for adding the outputs of the multiplier 62. And a second FIR filter 6 for Lch that convolves a pattern representing n1 energy changes, a delay device 71 that delays the output signal of the adder 53, for example, at each sampling cycle, and a delay device 71 A second FIR filter 7 for Rch which is composed of a multiplier 72 connected to an arbitrary output and an adder 73 for adding the output of the multiplier 72, and which convolves a pattern representative of n2 energy changes. Including.

According to this embodiment, the Lch of the first embodiment is
Since the first FIR filter 1 for Rch and the first FIR filter 3 for Rch are unified by the first FIR filter 5, the configuration is further simplified. The stereo effect synthesized by the adder 203 or the like is the second FI for Lch.
The R filter 6 and the second Rch FIR filter 7 reform the reverberation sound.

FIG. 5 is a diagram showing a reverberation adding apparatus according to a third embodiment of the present invention. The reverberation adding device shown in the figure has one
The pattern representative of the energy of the stage is composed of an FIR filter and an FIR filter forming a reverberation pattern. The order of the patterns is different from that in the first and second embodiments, but the same effect is obtained even if the order is different. Further, one stage can be divided into a front stage and a rear stage. Multipliers 201 and 202 for inputting the stereo Lch digital signal and the Rch digital signal and adjusting the respective levels, and the multipliers 201 and 202. 203 for adding the outputs of the above, a delay device 81 for delaying the output signal of the adder 203 for each sampling cycle, and the delay device 8
1 is connected to an arbitrary output of the multiplier 82, and an adder 83 for adding the output of the multiplier 82, the FIR filter 8 for convolving the reverberation pattern of k1 energy, and the delay device 81. A delay device 91 that delays the output for each sampling cycle, a multiplier 92 that is connected to an arbitrary output of the delay device 91, an output of the multiplier 92, and an addition of the output of the adder 83 And an FIR filter 9 for convolving the reverberation pattern of k2 energy, a delay device 101 for delaying the output of the delay device 81, for example, every sampling cycle, and an arbitrary output of the delay device 101. The reverberation pattern of k3 pieces of energy is composed of a multiplier 102 connected and an adder 103 that adds the output of the multiplier 102 and further adds the output of the adder 83. FIR filter 10 convolving the
And a delay device 111 that delays the output of the adder 93 for each sampling cycle, a multiplier 112 connected to an arbitrary output of the delay device 111, and an output of the multiplier 112 to form an Lch output. And an adder 113 for
FIR filter 11 for convolving k4 reverberation patterns
And an output of the adder 103 is delayed for each sampling period, a multiplier 122 connected to an arbitrary output of the delay device 121, and an output of the multiplier 122 are added to form an Rch output. And an FIR filter 12 for convolving k5 reverberation patterns.

FIG. 6 shows Lch second stage input and Rch of FIG.
It is a figure which shows the 2nd stage input. As shown in this figure, when a reverberation sound of 2 seconds is created, for example, in the first half of 1 second, the left-right correlation is set to 1 by the front stage of the FIR filter of the first stage and the FIR filter 11 of the second stage and Depending on the setting of 12, in the latter half of 1 second, the correlation can be reduced by the left and right independent calculation by the rear stage of the FIR filter of the first stage to give a feeling of expansion. In a music venue, when a sound is generated, the amount of reflection is small in the initial stage and thus has a sound source direction, but in the latter period, the amount of reflection increases and does not have a sound source direction. According to the example, the reverberation characteristic of the stereo sound is directional in the early stage of the generation of the stereo sound, but is lost in the latter stage, and the reverberation characteristic of the music venue can be reproduced.

[0018]

As described above, according to the present invention, a plurality of FIR filters are connected in series, and at least one of them is convolved with a pattern representative of energy change, so that the number of multiplications can be reduced. It can be significantly reduced and low cost can be achieved. Since it is composed of an FIR filter, there is an advantage that there is no periodicity. Further, it is possible to use a common FIR filter for convolving a pattern representative of energy changes in the formation of reverberant sounds of stereo left and right sounds, and it is possible to reduce the number of FIR filters and further reduce the cost. Further, the FIR filter for convolving the pattern representative of the energy change in the formation of the reverberation of the stereo left and right sounds is divided into the FIR filters of the front stage and the rear stage, the pattern of the front stage FIR filter is made common, and the pattern of the rear stage FIR filter is formed. By making them different, the spread of reverberant sound is further improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a reverberation adding apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating setting of coefficients of the multiplier shown in FIG.

FIG. 3 is a diagram illustrating setting of a multiplication coefficient when the reverberation sound characteristic is discrete.

FIG. 4 is a diagram showing a reverberation adding device according to a second embodiment of the present invention.

FIG. 5 is a diagram showing a reverberation adding device according to a third embodiment of the present invention.

6 is a diagram showing Lch second stage input and Rch second stage input of FIG. 5;

[Explanation of symbols]

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 1
2 ... FIR filter

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location H04S 1/00 D 8421-5H

Claims (3)

[Claims] 1. An F which forms a reverberation by delaying a digital signal, applying a coefficient to each delayed signal to adjust the amplitude, and adding and outputting these amplitude-adjusted signals.
A reverberation adding device comprising an IR filter, wherein a plurality of the FIR filters are connected in series, and at least one of them is convolved with a pattern representative of energy change. 2. An FIR for convolving a pattern representative of energy changes in stereo reverberation of left and right sounds.
The reverberation adding apparatus according to claim 1, wherein the filter is shared. 3. An FIR that convolves a pattern representative of energy changes in stereo reverberation of left and right sounds.
The filter is divided into a front stage and a rear stage FIR filter, the pattern of the front stage FIR filter is made common, and the rear stage F
The reverberation adding apparatus according to claim 2, wherein the patterns of the IR filters are different.