JP2949925B2 - Sound effect addition discriminator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound effect addition discriminating apparatus for discriminating a stereo input sound signal between music and an announcement, and determining a sound effect addition rate such as a reflected wave or reverberation.

[0002]

2. Description of the Related Art In recent years, as sound effect adding functions such as reflected waves and reverberation have become widespread in home audio and car audio, unnecessary sound effects for news programs such as news are automatically generated when FM broadcasts are received. There is a demand for a sound effect addition discriminating device as a system for preventing the effect.

FIG. 5 shows a sound effect addition discriminating apparatus which has already been proposed by the present inventor. In FIG. 5, 1, 2
Are an L signal input terminal and an R signal input terminal of a stereo signal digitized for each sampling period.
Reference numeral 3 denotes an input signal adder for the L signal and the R signal. 4 detects the number of silence signals based on the absolute value of the L + R signal level in the frame during the transition, and judges whether the frame is an announcement signal frame or a non-input frame based on the number of silence signals. The number-of-times determining means 5 and the L signal and the R signal
Level difference discriminating means for discriminating between music and announcement from the absolute value of the signal level difference. 6 is a sound effect generating means for generating a reflected wave, reverberation, etc., 7 is a sound effect volume for setting a sound effect level, 8 is an output signal addition processing section of the sound effect and the L signal, and 9 is a sound effect and R signal. Output signal adding section, 1
0 and 11 are an L signal output terminal and an R signal output terminal, respectively.

[0004] The operation of the sound effect addition discriminating apparatus configured as described above will be described below. First, L
The L signal from the signal input terminal 1 and the R signal from the R signal input terminal 2
The signal is input to the silence count determining means 4. The process of the silence frequency discriminating means 4 will be described with reference to the flowchart of FIG. First, it is determined whether or not the input signal is sound or no sound (step 1). If the absolute value of the L + R signal is equal to or more than a certain value, it is determined that there is sound, and the process proceeds to step 3. If it is less than a certain value, it is determined that there is no sound, the number of times of silence is updated (step 2), and the process proceeds to step 3.

Next, it is determined whether or not the detection of a silent signal in the frame has been completed (step 3). If it has been completed, it is determined whether or not it is in the state of silence announcement (step 4).
Is completed. In step 4, if the number of silences in the frame is less than a certain value, the process of the level difference discriminating means 5 is executed, and if it is more than a certain value, it is judged whether or not there is no input (step 5). In step 5, if the number of silences is equal to or more than a certain value, it is determined that there is no input, and step 11
Move on to If it is less than a certain value, it is determined that the input is an announcement, and the sound effect volume 7 is subtracted (step 6). In step 11, the number of silences is reset, and the process of the number-of-silences discriminating means 4 ends.

The processing of the level difference determining means 5 will be described with reference to a flowchart shown in FIG. In FIG. 7, first, it is determined whether or not the input signal is music (step 7).
I do. The absolute value of the difference between the input L signal and R signal is
If it is more than a certain value, it is determined that the music is music, and if it is less than a certain value, it is determined that it is not music, and the process proceeds to step 9.
In step 9, it is determined whether or not the input signal is an announcement. If the absolute value of the difference between the input L signal and R signal is less than a certain value, it is determined that an announcement is made and the process proceeds to step 10. If it is more than a certain value, it is determined that the signal is neither music nor announcement and cannot be determined. The processing of the means 5 is completed, and the routine proceeds to FIG. If it is determined that the music is music, the sound effect volume 7 is added (step 8),
If it is determined that the announcement has been made, the sound effect volume 7 is subtracted (step 10), the processing of the level difference determination means 5 ends, and the routine proceeds to FIG.

[0007] The L and R signals from the L signal input terminal 1 and the R signal input terminal 2 are added in an input signal addition processor 3 and input to a sound effect generator 6. The sound effects such as the reflected wave and reverberation generated here are output to the silence number discriminating means 4.
The level is determined by a preset sound effect volume 7 by the level difference discriminating means 5, added to the input L signal and the output signal adder 8, and output from the L signal output terminal 10. Similarly, the R signal is added by the output signal adder 9 to the sound effect set by the sound effect volume 7 and output from the R signal output terminal 11.

As described above, even in the above-described conventional sound effect adding and discriminating apparatus, the music signal and the announcement signal can be discriminated on the basis of the number of times of detection of the silent signal and the level difference between the L signal and the R signal. You can control the volume.

[0009]

However, in the above-described conventional sound effect adding / discriminating apparatus, the silent signal threshold value used as the reference for the silent determination used in the silent count determining means is fixed.
When the input signal level is large, there is a problem that the judgment rate of sound increases, and when the input signal level is low, the judgment rate of silence increases.

The present invention solves the above-mentioned conventional problem. By determining a silent signal threshold value according to an input level at any time, it is possible to always accurately distinguish between a music and an announcement regardless of the level of the input level. It is an object of the present invention to provide an excellent sound effect addition discriminating apparatus that can be used.

[0011]

According to the present invention, in order to achieve the above object, the maximum value of the absolute value of the audio signal is detected in a frame obtained by dividing an input digital audio signal into predetermined sections, and the maximum value is detected. 1 / α is set as a silence signal estimation threshold value of the next frame, a silence signal threshold value determining means for determining a silence signal threshold value of the next frame from the silence signal estimation threshold value and a silence signal threshold value of the current frame, and the number of silence signals in the frame. Means for determining whether the frame is an announcement signal frame or a non-input frame based on the number of times, and an absolute value of a level difference between the L signal and the R signal. Level difference determining means for determining whether the frame is a music signal frame or an announcement signal frame,
A sound effect generator for generating a sound effect to be added to the digital sound signal, a sound effect volume for setting a ratio of sound effect addition according to the result of the determination, and adding the sound effect and the digital sound signal. And a sound effect additional signal output section for outputting.

[0012]

Therefore, according to the present invention, the silence signal threshold is set by the silence signal threshold setting means according to the magnitude of the input signal level, and the appropriate silence signal threshold is always used by the silence frequency discriminating means. Is improved.

[0013]

FIG. 1 is a block diagram showing an embodiment of the present invention. In FIG. 1, reference numerals 12 and 13 denote an L signal input terminal and an R signal input terminal of a stereo signal digitized for each sampling period, and 14 denotes an input signal addition processing unit for the L signal and the R signal. 15 detects the maximum value of the input signal within the frame of a certain section, and uses 1 / α as the silence signal estimation threshold of the next frame, and calculates the silence signal threshold of the next frame from the silence signal estimation threshold and the silence signal threshold of the current frame. Is a silent signal threshold value setting means for determining the threshold value. Numeral 16 compares the absolute value of the L + R signal and the silence signal threshold value for each frame, detects the number of silence signals, and determines whether the frame is an announcement signal frame or a non-input frame based on the number of silences. Reference numeral 17 denotes a level difference determining means for determining a music signal and an announcement signal from the absolute value of the level difference between the L signal and the R signal. Reference numeral 18 denotes sound effect generating means for refining reflected waves, reverberation, and the like. 19 is a sound effect volume for setting the sound effect level, 20 is an output signal addition processing unit for the sound effect and the L signal whose level is set by the sound effect volume 19, and 21 is a sound signal and an R signal for which the level is set by the sound effect volume 19 This is an output signal addition processing unit. 22, 2
Reference numeral 3 denotes an L signal output terminal and an R signal output terminal.

Next, the operation of the above embodiment will be described.
First, the L signal and the R signal are input to the silence signal threshold setting means 15 from the L signal input terminal 12 and the R signal input terminal 13, respectively. The processing in the silent signal threshold setting means 15 will be described with reference to the flowchart of FIG. In FIG.
The R signal and the L signal are added, and it is determined whether or not the absolute value is the maximum value in a frame divided into a certain section (step 1). If it is not the maximum value, the process proceeds to step 3, and if it is the maximum value, the maximum value is updated (step 2) and the process proceeds to step 3. Next, the end of the frame is determined (step 3). If the frame is not ended, the processing shifts to the processing of the silence count determining means 16 shown in FIG. 3. If the frame is ended, the maximum value obtained in step 2 is 1 / α (where α> 1) Multiply to obtain a silence signal estimation threshold value of the next frame (step 4). further,
The silence signal threshold value of the next frame is updated according to the following equation (1) (step 5), and the process proceeds to the silence frequency discriminating means 16.

K _i = K _i−1 − (K _i−1 −KN) × β (1) where K: silence signal threshold KN: silence signal estimation threshold i: frame number β: β <1 The processing of the means 16 will be described with reference to the flowchart of FIG. The silence count determining means 16 first determines whether the input signal is vocal or silent (step 6).
If it is equal to or greater than the silence signal threshold set in step 5, it is determined that there is sound, and the process proceeds to step 8. If it is equal to or less than the silence signal threshold, it is determined that there is no sound. Move on. In step 8, it is determined whether or not silence detection in the frame has been completed. If the processing has been completed, a no-announce announcement is determined (step 9). If the processing has not been completed, the process of the silence frequency determination means 16 is terminated. In step 9, if the number of silences in the frame is equal to or less than a certain value, the processing of the level difference determining means 17 shown in FIG. 4 is executed, and if it is equal to or more than a certain value, no input is determined (step 10). In the no-input determination, if the number of times of silence is equal to or more than a certain value, it is determined that there is no input, and the process proceeds to step 12. If it is less than a certain value, the input signal is determined to be an announcement, and the sound effect volume 19 is subtracted (step 11). ), And proceed to step 12. In step 12, the number of silences is reset, and the process of the number-of-silences discriminating means 16 ends.

As shown in FIG. 4, the processing by the level difference discriminating means 17 is first determined to be music if the absolute value of the difference between the input L signal and R signal is greater than a certain value. Is added (step 14), and the routine proceeds to FIG. If it is less than a certain value, it is determined that the music is not music, and step 15
Move on to In step 15, it is determined whether or not the input signal is an announcement. If the absolute value of the difference between the input L signal and R signal is equal to or less than a certain value, it is determined that an announcement has been made, the sound effect volume 19 is subtracted (step 16), and the routine proceeds to FIG.
If the value is equal to or more than a certain value, the signal is not music or an announcement, and is determined as a signal that cannot be determined.

The L and R signals from the L signal input terminal 12 and the R signal input terminal 13 are added by an input signal addition processing unit 14 and input to a sound effect generation unit 18. Here, the level of the sound effect that has generated the reflected wave and reverberation is determined by the sound effect volume 19 set by the silence count determining means 16 and the level difference determining means 17, and the input L signal,
The input R signal is added to the output signal adders 20 and 21, respectively, and the L signal output terminal 22 and the R signal output terminal 2 are respectively added.
3 is output.

As described above, according to the present embodiment, the silent signal threshold setting means 15 estimates the silent signal threshold suitable for the input level for each frame divided into a predetermined section and updates the silent signal threshold. The silence determination using the silence signal threshold value in the silence frequency discriminating means 16 can obtain a constant discrimination result regardless of the difference in the input signal level.

[0019]

As is clear from the above embodiment, the present invention obtains the maximum value from the input signal in the frame divided into a certain section, and uses 1 / α as the threshold for estimating the silence signal of the next frame. By providing a silence signal threshold determination unit that sets a silence signal threshold of the next frame from the signal estimation threshold and the silence signal threshold of the current frame, the silence signal threshold can be set according to the fluctuation of the input level, so that an appropriate silence is always obtained. There is an effect that a signal threshold can be used and the accuracy of the silence judgment can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a sound effect addition determination device according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating a processing operation of a silence signal threshold setting unit according to the embodiment;

FIG. 3 is a flowchart showing a processing operation of a silence frequency discriminating unit in the embodiment.

FIG. 4 is a flowchart illustrating a processing operation of a level difference determining unit according to the embodiment;

FIG. 5 is a block diagram showing a conventional sound effect addition determination device.

FIG. 6 is a flowchart showing a processing operation of a silence frequency discriminating means in a conventional example.

FIG. 7 is a flowchart showing a processing operation of a level difference discriminating means in a conventional example.

[Explanation of symbols]

 Reference Signs List 14 Input signal addition processing unit 15 Silence signal threshold setting unit 16 Silence count determination unit 17 Level difference determination unit 18 Sound effect generation unit 19 Sound effect volume 20, 21 Output signal addition unit

────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification symbol FI H04S 1/00 H04S 1/00 N (56) References JP-A-4-359298 (JP, A) JP-A-5-22239 ( JP, A) JP-A-58-81599 (JP, A) JP-A-58-208796 (JP, A) JP-A-59-49026 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G10K 15/12 G10L 9/00 H04B 1/16 H04H 5/00 H04S 1/00

Claims (1)

(57) [Claims] 1. A maximum value of an absolute value of an audio signal is detected in a frame obtained by dividing an input digital audio signal into a predetermined section, and 1 / α of the maximum value is set as a silent signal estimation threshold value of a next frame. A silence signal threshold determining means for determining a silence signal threshold of the next frame from the silence signal estimation threshold and the silence signal threshold of the current frame, and detecting the number of silence signals in the frame; Means for determining whether or not the frame is a frame or a no-input frame; and determining whether the frame is a music signal frame or an announcement signal frame based on an absolute value of a level difference between the L signal and the R signal. Level difference discriminating means, sound effect generating means for generating a sound effect to be added to the digital sound signal, and setting a ratio of sound effect addition according to the result of the discrimination. And sound effect volume, sound effect adding device for discriminating a sound effect adding signal output unit for outputting by adding the above-mentioned sound effects and the digital audio signal.