JP2000115897A - Sound processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make words of a center channel clear, even when the total sound volume is small at reproduction by extracting an audio signal of word components included in the audio signal of the center channel and adding it to the audio signal outputted from a multi-channel decoder. SOLUTION: A word extraction part 3 removes components of the audio signals of a left(L) channel and a right(R) channel from the audio signals of the respective channel under the control of a control part 4. Furthermore, a bandpass filter 7 which passes only the frequency band of the voice of a human extracts the audio signal of the word components included mainly in a C channel. The extracted audio signal of the word components is added to the source audio signal of the C channel outputted from the multichannel decoder 2. The control part 4 controls the process for increasing the word components of the word extraction part 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound processing apparatus for reproducing a multi-channel audio signal capable of providing a sense of reality.

[0002]

2. Description of the Related Art Conventionally, when enjoying a movie or the like at home, terrestrial broadcasting such as television broadcasting has been the mainstream. However, in recent years, with the spread of recording media such as video tapes and video disks, satellite broadcasting, and the like, it has become possible to enjoy the sound of movies and the like with a sense of presence as if listening to sound in a movie theater or the like. I have.

An audio signal recorded on a recording medium such as a video tape or a video disk and an audio signal from a satellite broadcast or the like are subjected to matrix processing and encoding processing on audio signals of a plurality of channels (multi-channels). The audio signal is converted into an audio signal having a smaller number of channels than the number of signal channels, recorded on a recording medium, or transmitted as a radio signal. These audio signals are converted into audio signals of the original number of signal channels and output by a device having a dedicated decoder such as an AV (Audio Visual) amplifier or an AV processor.

[0004] For example, an audio signal that has been subjected to matrix processing is a left (L) channel, a center (C)
The audio signal is restored to an audio signal of four signal channels of a channel, a write (R) channel, and a surround (S) channel and output. Also, the audio signal that has been subjected to the encoding processing is a left (L) channel, a center (C) channel, a right (R) channel, a surround left (SL) channel, a surround right (SR) channel, and a subwoofer (SW) channel. The audio signals of the six signal channels are restored and output.

[0005] Among these signal channels, the center channel audio signal plays a role to obtain clarity of speech (line) and a clear sense of localization, and the surround channel audio signal includes moving sound, environmental sound, and so on. The subwoofer channel audio signal plays a role of reproducing a sound such as a sound effect in a low-frequency range, etc.

FIG. 5 is a schematic diagram showing a schematic configuration of a conventional audiovisual system. In FIG. 5, a video and audio system 9 that can enjoy video and sound with a video signal and a multi-channel audio signal includes a signal supply device 5,
Sound processing device 1, amplifying device 6, monitor 10, left (L) speaker 11, center (C) speaker 12, right (R) speaker 13, surround left (SL) speaker 14, surround right (SR) speaker 15,
A subwoofer (SW) speaker 16 is provided.

[0007] The signal supply device 5 obtains a signal from a video tape, a video disc, a satellite broadcast, or the like, reproduces a video signal and an audio signal, and supplies a signal to each device. The video signal is supplied to the monitor 10, and the audio signal is supplied to the multi-channel decoder 2 of the audio processing device 1.

The audio processing device 1 performs signal processing such as decoding such as matrix processing and decompression processing on the audio signal supplied from the signal supply device 5, converts the audio signal into a plurality of channels of audio signals, and supplies the audio signals to the amplification device 6. Output. The multi-channel decoder 2, based on the control of the control unit 4,
From the encoded audio signal, six signal channels of a left (L) channel, a center (C) channel, a right (R) channel, a surround left (SL) channel, a surround right (SR) channel, and a subwoofer (SW) channel And outputs the audio signal to the amplifying device 6.

[0009] The amplifying device 6 amplifies the audio signal of each channel and outputs it to the speaker for each channel.

[0010]

In the above-described audiovisual system, when reproducing and enjoying a multi-channel audio signal without disturbing the surroundings at midnight or the like, the volume of the entire sound is increased by using the volume of the amplifying device. Or lower the volume of audio signals other than the center (C) channel that contains many dialogue sounds.

However, when the volume is reduced by using the volume of the amplifying device, the overall sound pressure is reduced, and the viewer can reproduce the multi-channel audio signal without disturbing others. The volume of dialogue such as characters in a movie or the like also decreases, so that the clarity of the dialogue is lost and the voice cannot be clearly heard.

When the volume of audio signals of channels other than the center (C) channel is lowered, only the center (C) channel is reproduced at a normal volume, that is, the words and effects of the center (C) channel are reduced. Since the sound or the like is reproduced normally, the balance of the sound pressure level with the other channels is lost, and the sense of presence cannot be obtained.

Accordingly, it is an object of the present invention to provide a sound processing apparatus capable of clarifying the words on the center channel when reproducing a multi-channel audio signal even when the overall volume is low.

[0014]

According to a first aspect of the present invention, there is provided an audio processing apparatus for performing signal processing on an encoded audio signal, converting the encoded audio signal into audio signals of a plurality of channels, and outputting the audio signal. A multi-channel decoder that performs decoding processing based on matrix processing or decompression processing to convert the audio signal into a plurality of channels; and, among the audio signals of the plurality of channels, a center channel audio signal to a left channel audio signal and a right channel audio signal. , And passes only a predetermined frequency band to extract a serif component audio signal included in the center channel audio signal, and adds it to the center channel audio signal output from the multi-channel decoder. And serifs extraction unit, which controls the processing of the multi-channel decoder, is characterized by comprising a control unit for controlling the speech extraction unit when the processing for enhancing the speech component is selected.

According to a second aspect of the present invention, there is provided an audio processing apparatus for performing signal processing on an encoded audio signal, converting the encoded audio signal into audio signals of a plurality of channels, and outputting the audio signal. A multi-channel decoder that performs decoding processing based on the multi-channel audio signal and a level detection unit that detects the level of each channel audio signal output from the multi-channel decoder; Remove the components of the left channel audio signal and right channel audio signal from the center channel audio signal,
A speech extraction unit that passes only a predetermined frequency band, extracts a speech component audio signal included in the audio signal of the center channel, and adds the audio signal to the audio signal of the center channel output from the multi-channel decoder; A control unit controls the processing of the decoder and controls a process of enhancing the serif component of the serif extraction unit based on the detection result of the level detection unit.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic diagram for explaining a schematic configuration of a sound processing apparatus according to the present invention. FIG. 2 is a schematic diagram for explaining the serif component enhancement processing of the sound processing apparatus of the present embodiment. In FIG. 1, a sound processing apparatus 1
Is a multi-channel decoder 2 and a speech extraction unit 3
And a control unit 4. The audio processing device 1 performs signal processing such as decoding on the audio signal supplied from the signal supply device 5, converts the audio signal into a plurality of channels of audio signals, and outputs the audio signals to the amplification device 6. The amplification device 6 amplifies the audio signal of each channel and outputs it to the speaker for each channel.

The multi-channel decoder 2 performs a decoding process such as a matrix process or an expansion process on the encoded audio signal supplied from the signal supply device 5, and performs a left (L) channel and a center (C) channel. , Right (R) channel, surround left (S
L), surround light (SR) channel, and subwoofer (SW) channel audio signals are output.

The speech extraction unit 3 converts the audio signal of the center (C) channel out of the audio signals of each channel based on the control of the control unit 4 described later.
A band-pass filter (BP) that removes audio signal components of the left (L) channel and the right (R) channel and passes only the frequency band of human voice
F: Band Pass Filter) 7, mainly center (C)
The audio signal of the serif component included in the channel is extracted, and the extracted audio signal of the serif component is added to the original audio signal of the center (C) channel output from the multi-channel decoder.

The control unit 4 includes a multi-channel decoder 2
And the processing for enhancing the speech component in the speech extraction unit 3 is controlled. The control unit 4 determines whether or not to perform the process of enhancing the serif component,
When a viewer gives an instruction using an operation unit (not shown),
The dialogue extracting unit 3 is operated.

Further, the determination as to whether or not to perform the process of enhancing the serif component may be made based on the size of the volume of the amplifier 6. That is, the amplification device 6
The dialogue extraction unit 3 may be activated when the volume that determines the overall volume of the audio signal falls below a predetermined level.

The processing of the dialogue extracting unit 3 in the sound processing apparatus 1 will be specifically described. When the process of enhancing the serif component is selected, the audio signal supplied from the signal supply device 5 is input to a multi-channel decoder, subjected to a decoding process such as a matrix process or an expansion process, and is subjected to a left (L) channel, The audio signals are converted into audio signals of a center (C) channel, a right (R) channel, a surround left (SL) channel, a surround right (SR) channel, and a subwoofer (SW) channel.

Of the audio signals output from the multi-channel decoder 2, the audio signals of the left (L) channel and the right (R) channel are also input to the dialogue extracting unit 3.

In the serif extraction unit 3, the left (L) channel audio signal is input to a multiplier A1, and the right (R) channel audio signal is input to a multiplier A2. The multipliers A1 and A2 are each set with a coefficient of “−1”, and the audio signals output from the multipliers A1 and A2 are the inverse of the original left (L) channel or right (R) channel audio signal. It becomes a phase component.

The audio signals output from the multipliers A1 and A2 are input to multipliers A3 and A4. Multiplier A
3 and A4 are left (L) channel and right (R)
A coefficient is set for matching the level of the audio signal of the opposite phase component of the channel with the level of the left (L) channel and right (R) channel audio signals mixed in the center (C) channel audio signal. .

The level-adjusted left (L) channel opposite-phase component audio signal output from the multipliers A3 and A4 and the level-adjusted right (R)
The audio signal of the opposite phase component of the channel is added to the adder B1.
Is added to the original audio signal of the center (C) channel output from the multi-channel decoder to reduce the crosstalk between the audio signal of the center (C) channel and the left (L) channel and the right (R) channel. be able to.

Here, the crosstalk of each channel will be described. There are various methods for decoding audio signals such as audio accompanied by video signals, such as a decoding method using matrix operation processing and a decoding method using compression processing on audio signals.

In the method of decoding the audio signal encoded by the matrix operation processing, crosstalk between the left (L) channel and the center (C) channel and between the right (R) channel and the center (C) channel are suppressed. However, due to the configuration of the encoding method and the decoding method, independent separation cannot be obtained, and the left (L)
Crosstalk occurs between the channel and the center (C) channel, and between the right (R) channel and the center (C) channel.

In the decoding method using the compression processing on the audio signal, since the compression processing is performed on the audio signal of each channel by the discrete processing, the separation between the channels is independent.
However, when producing a surround track, sounds are mixed between channels in order to give a sense of connection and spread of sounds.

Therefore, the sound processing apparatus 1 of the present embodiment
Is to remove the left (L) channel audio signal component and the right (R) channel audio signal component contained in the center (C) channel audio signal from the original center (C) channel audio signal. Crosstalk between the (L) channel, the right (R) channel, and the center (C) channel can be reduced.

The audio signal output from the adder B1 is input to the band pass filter 7.
The band pass filter 7 is a filter having a characteristic of extracting only a human voice band,
An audio signal having a frequency component of z to 5 KHz is passed. As a result, only the serif component can be extracted from the audio signal of the center (C) channel. The pass band of the band-pass filter 7 is not limited to the above-mentioned band, but may be a band of voice when a human is talking normally.

The audio signal output from the band pass filter 7 is output after being multiplied by a predetermined coefficient by a multiplier A5. The coefficient of the multiplier A5 is a coefficient that determines how much the audio signal of only the serif component included in the center (C) channel is enhanced with respect to the original audio signal of the center (C) channel. This coefficient may be a predetermined coefficient, or may be set by a viewer using an operation unit or the like.

The audio signal output from the multiplier A5 is added by the adder B2 to the original audio signal of the center (C) channel output from the multi-channel decoder. As a result, as shown in FIG. 2, the center (C) channel audio signal output from the center (C) capeika via the amplifying device 6 is output as an audio signal in which the serif component is enhanced.

Therefore, in the above-described dialogue extracting section 3, the left (L) channel and right (R) channel audio signals mixed in the center (C) channel audio signal are removed, and the band-pass filter is used. Since the audio signal components other than the human voice band are removed and added to the original audio signal of the center (C) channel and output, the audio signal of the center (C) channel with an enhanced serif component can be obtained. it can.

Further, the sound processing apparatus of the present invention may perform a process of enhancing the serif component based on the level of the audio signal of each channel output from the multi-channel decoder.

FIG. 3 is a schematic diagram showing a schematic configuration of another embodiment of the sound processing apparatus of the present invention. In FIG. 3, the sound processing device 1 includes a multi-channel decoder 5,
A level detection unit 8, a dialogue extraction unit 3, and a control unit 4 are provided. 1 are given the same reference numerals.

The multi-channel decoder 2 performs a decoding process such as a matrix process and an expansion process on the audio signal supplied from the signal supply device 5 to obtain a left (L) channel, a center (C) channel, and a right (R) channel. , A surround left (SL) channel, a surround right (SR) channel, and a subwoofer (SW) channel.

The level detector 8 compares the level of the audio signal of each channel with a predetermined threshold, and notifies the controller 4 of the comparison result.

The serif extraction unit 3 removes the components of the left (L) channel and right (R) channel audio signals from the center (C) channel audio signal under the control of the control unit 4 described later. Further, a band-pass filter 7 that passes only the frequency band of a human voice extracts a speech component audio signal mainly contained in the center (C) channel, and converts the audio signal into an original audio signal of the center (C) channel. Add and output.

The control unit 4 is a multi-channel decoder 2
And the processing for enhancing the speech component in the speech extraction unit 3 based on the detection result from the level detection unit 8.

FIG. 4 is a schematic diagram for explaining the processing operation of the dialogue extraction unit in the sound processing apparatus of this embodiment. As shown in FIG. 4, the control unit 4 determines in advance the correlation between the levels of the audio signals between the respective channels and the level of the audio signals of the respective channels based on the detection result from the level detector 8. The processing for enhancing the serif component is controlled based on the comparison result with the threshold value.

As shown in FIGS. 4 (a), 4 (c) and 4 (f), when the level of the audio signal of each channel is higher than the threshold value, the speech extracting unit 3 is not operated. Then, the audio signal of each channel is output to the amplifier 6 as it is.

As shown in FIGS. 4B and 4G, when the level of the audio signal of each channel is lower than the threshold value, the dialogue extracting unit 3 is operated to set the center (C). ) Add a serif component audio signal to the channel audio signal and output.

As shown in FIG. 4D, when the level of the audio signal of each channel is lower than the threshold value and the level of the audio signal of the center (C) channel is higher than the levels of the other audio signals, Even if the level of the audio signal of each channel is lower than the threshold value, the center (C) is not added to the audio signal of the center (C) channel without adding the audio signal of the speech component.
Outputs the audio signal of the channel as it is.

Thus, for example, in a movie or the like, in a scene in which a person who is speaking the lines gradually moves away from the screen, only the audio signal of the center (C) channel is prominently heard from a certain level. The entire audio signal can be heard in a well-balanced manner based on the state of the screen without any trouble.

Further, as shown in FIG. 4E, only the level of the audio signal of the center (C) channel is higher than the threshold value, and the levels of the audio signals of the other channels are lower than the threshold value. In this case, the audio signal of each channel is output as it is without operating the speech extracting unit 3.

Further, as shown in FIG. 4H, only the level of the audio signal of the center (C) channel is lower than the threshold value, and the levels of the audio signals of the other channels are higher than the threshold value. In this case, the speech extraction unit 3 is operated to add a speech component audio signal to the center (C) channel audio signal and output the resultant signal.

As described above, the speech extraction unit is operated based on the level of the audio signal of each channel output from the multi-channel decoder, and the center (C)
By adding and outputting the audio signal of the serif component of the audio signal of the channel, the serif component can be enhanced corresponding to the video.

[0047]

According to the present invention, when reproducing audio signals of a plurality of channels, the words of the center channel can be made clear.

[Brief description of the drawings]

FIG. 1 is a schematic diagram for explaining a schematic configuration of a sound processing apparatus according to the present invention.

FIG. 2 is a schematic diagram for explaining a serif component enhancement process of the sound processing apparatus according to the embodiment.

FIG. 3 is a schematic diagram showing a schematic configuration of another embodiment of the sound processing apparatus of the present invention.

FIG. 4 is a schematic diagram for explaining a processing operation of a dialogue extracting unit in the sound processing apparatus of the embodiment.

FIG. 5 is a schematic diagram showing a schematic configuration of a conventional audiovisual system.

[Explanation of symbols]

1. Acoustic processing device, 2. Multi-channel decoder, 3. Serif extraction unit, 4. Control unit, 5. Signal supply device, 6. Amplification device, 7. BPF (Band pass filter) ), 8... Level detector, 9... Video supply system, 10... Monitor, 11... L speaker, 12.
C speaker, 13 R speaker, 14 SL speaker, 15 SR speaker, 16 SW speaker.

Claims (2)

[Claims] 1. An audio processing apparatus for performing signal processing on an encoded audio signal to convert the audio signal into audio signals of a plurality of channels and outputting the audio signal, wherein the audio signal is subjected to decoding processing based on matrix processing or decompression processing. A multi-channel decoder for converting to a channel audio signal, and a predetermined frequency band by removing components of a left channel audio signal and a right channel audio signal from a center channel audio signal among the plurality of channel audio signals. And a speech extraction unit that extracts a speech component audio signal included in the center channel audio signal and adds the extracted audio signal to the center channel audio signal output from the multi-channel decoder.
A sound processing apparatus, comprising: a control unit that controls the processing of the multi-channel decoder and controls the dialogue extraction unit when a process of enhancing a speech component is selected. 2. An audio processing apparatus for performing signal processing on an encoded audio signal to convert the encoded audio signal into audio signals of a plurality of channels and outputting the audio signals, wherein the audio signal is subjected to a decoding process based on a matrix process or an expansion process. A multi-channel decoder that converts the audio signal into a channel audio signal; a level detection unit that detects a level of the audio signal of each channel output from the multi-channel decoder; The audio signal of the channel and the audio signal of the light channel are removed, and only a predetermined frequency band is passed to extract the audio signal of the speech component included in the audio signal of the center channel. A serif extraction unit that adds the audio signal of the center channel output from the coder, and controls the processing of the multi-channel decoder and enhances the serif component of the serif extraction unit based on the detection result of the level detection unit. A sound processing apparatus comprising: a control unit that controls processing.