JPH06165079A - Down mixing device for multichannel stereo use - Google Patents

Abstract

(57) [Abstract] [Purpose] Determines whether the input multi-channel acoustic signal is music or voice, and performs signal processing based on the determination result when mixing down to 2ch signal, so that the program source Realize a down-mixing device for multi-channel stereo that enables suitable 2ch sound reproduction. [Structure] A multi-channel acoustic signal is sent to the down-mixing means 1, and L / R of the multi-channel acoustic signal is used.
The main channel signals are added by the adding means 2 and then supplied to the music / voice discrimination means 3. The music / voice discrimination means 3 discriminates continuously or discretely whether the acoustic signal is music or voice based on the input addition signal, and transmits the discrimination result to the parameter varying means 4. The parameter changing means 4 uses the downmixing means 1 based on the determination result.
In the case of (2), the acoustic parameter relating to the signal processing executed for the mixdown to the 2ch signal is corrected to the optimum value for music (voice) reproduction when it is determined to be music (voice).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mixes down multi-channel audio to 2 ch in an AV device such as a high-definition TV that is accompanied by multi-channel audio when the system configuration is such that the speaker for sound reproduction has only 2 ch (ch). The present invention relates to a multi-channel stereo down-mixing device.

[0002]

2. Description of the Related Art In recent years, in the AV (audio / visual) field, the technological trend is changing from original sound reproduction to original sound field reproduction, and as represented by high-definition TV and the like, the sound reproduction is performed by the conventional L sound reproduction. A multi-channel reproduction system in which a center channel and a surround channel are added to the / Rch stereo signal is being realized. However, in the case of the multi-channel reproduction system, at least one speaker has to be arranged behind or on the side of the viewer, and it is considered that there are not a few users who dislike this and watch in normal stereo 2ch reproduction. In order to support the above viewers, it is necessary to mix down the audio signals transmitted in the multi-channel to 2ch.

FIG. 3 is a block diagram of a conventional multi-channel stereo down-mixing device. In FIG. 3, 10 is the input Lch, Rch, C (center) c
2c of sound signals of 4 channels in total of h and S (surround) channels
It is a down-mixing unit for mixing down to h. Reference numeral 6 denotes a center channel volume adjusting unit for adjusting the volume of the Cch signal, 11 denotes a surround channel volume for adjusting the volume of the Sch signal, and these are components of the down mixing unit 10. is there.

The operation of the multi-channel stereo down-mixing device configured as described above will be described below with reference to the drawings. In FIG. 3, L / R main ch, C ch, S demodulated from a decoder or the like (not shown)
Acoustic signals of a total of 4 channels are input to the down mixing unit 10. Inside the down mixing section 10, C
The volume of the ch signal is adjusted by the gain coefficient d in the center channel volume adjusting unit 6 to adjust the volume. Further, the volume of the Sch signal is adjusted by multiplying the gain coefficient b in the surround channel volume 11. On the other hand, L / R main c
After the volume-adjusted Cch signal is added to the h signal, the volume-adjusted Sch signal is also added, and the h signal is output as a 2ch signal from the down mixing unit.

As the gain coefficients d and b, a value such as 0.7 is adopted as a fixed value. As described above, the signal obtained by adding the Cch and Sch signals to the L / R main ch signal at a constant ratio is reproduced by the speaker of 2ch,
Natural sound image movement between the left and right and sound image localization can be secured, and a surround feeling can be achieved although it is imperfect.

[0006]

However, in the above configuration, the gain coefficient b of the surround channel volume 11 is fixed. Therefore, for example, if the coefficient b is fixed to an optimum value for realizing a realistic sensation when reproducing music, a comparatively large surround sound is mixed with the sound and reproduced from the front speaker during sound reproduction. Of 4
There is a problem that the sense of clarity is reduced as compared with the case of reproducing the ch speaker. It is an object of the present invention to solve the above problems and to provide a down-mixing device for a multi-channel stereo capable of ensuring a sufficient sense of presence when reproducing music and the like and ensuring a sense of clarity when reproducing sound such as news programs. To do.

[0007]

In order to achieve the above object, a multi-channel stereo down-mixing device according to the present invention uses an input multi-channel audio signal 2c.
down mixing means for mixing down to the h signal,
At least 1c of the input multi-channel audio signal
Music / voice discrimination means for discriminating whether the input signal is music or voice using the signal of h, and a parameter variable for changing the acoustic parameter inside the down-mixing means based on the discrimination result by the music / voice discrimination means. And means.

[0008]

According to the present invention having the above-mentioned structure, the parameter varying means, based on the continuous or discrete discrimination result of the music / speech discriminating means, outputs the acoustic parameter relating to the signal processing executed in the down-mixing means when the music is reproduced. Change the value to the optimum value for playback, or to the optimum value for voice playback during voice playback. Therefore, despite the 2ch speaker reproduction, for example, when the video / audio software is music, realistic reproduction can be performed, and in the case of audio, clear reproduction can be performed. Optimal sound reproduction is possible.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A multi-channel stereo downmixing device according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the structure of a multi-channel stereo down-mixing device according to an embodiment of the present invention. In FIG. 1, reference numeral 1 is a down-mixing means for mixing down the input Lch, Rch, C (center) ch, S (surround) ch sound signals of a total of 4 ch into 2 ch, and 2 is the input L / L. An adding means for adding the Rch signals, 3 is a music / voice determining means for determining whether the input acoustic signal is music or voice based on the added L / Rch signals, and 4 is the music / voice determining means 3 It is a parameter changing means for changing the acoustic parameter relating to the signal processing executed in the down-mixing means 1 on the basis of the result of the discrimination in (1).

The operation of the down-mixing device for multi-channel stereo according to the embodiment of the present invention constructed as above will be described below. In FIG.
L / R main c demodulated from a decoder (not shown)
Sound signals of a total of 4 channels of h, Cch, and Sch are input to the down mixing means 1. On the other hand, the L / R main ch signal of the 4 ch input signals is added by the adding means 2 and then input to the music / voice discrimination means 3 to continuously or discretely determine whether the current acoustic signal is music or voice. To be determined. The determination result is transmitted to the parameter changing means 4. On the basis of the above determination result, the parameter varying means 4 is optimum for music reproduction when the value of the acoustic parameter relating to the signal processing for mixing down to 2ch executed by the down mixing means 1 is determined to be music reproduction. To the value
If it is determined that the sound is reproduced, the value is changed to the optimum value for the sound reproduction.

As described above, the acoustic parameters relating to the signal processing for mixing down to 2 ch performed by the down mixing means 1 are not fixed values but are variable according to the property of the reproduced acoustic signal, It is possible to realize optimal sound reproduction for the program source, even within the restriction of the speaker configuration.

Next, a multi-channel stereo down-mixing device according to a second embodiment of the present invention will be described.

FIG. 2 is a block diagram showing a configuration of a multi-channel stereo down-mixing device according to a second embodiment of the present invention. FIG. 1 specifically defines signal processing in the down-mixing means. Is. Figure 2
In FIG. 1, the down-mixing means 1, the adding means 2, and the music / voice discrimination means 3 are the same as those in FIG. The center channel volume adjusting unit 6 is the same as that of the conventional example shown in FIG. Reference numeral 5 is a volume varying means for changing a gain coefficient of a volume adjusting section, which will be described later, which constitutes the downmixing means 1, based on the discrimination result of the music / voice discrimination means 3. Reference numeral 7 is an Lch volume adjusting section for adjusting the gain of an added signal of the Lch signal input to the downmixing means 1 and the volume-adjusted Cch signal, and 8 is the downmixing means 1
An Rch volume adjusting section for adjusting the gain of the added signal of the Rch signal input to the and the Cch signal whose volume is adjusted,
Reference numeral 9 denotes a surround-channel volume adjusting section for adjusting the gain of the Sch signal input to the down-mixing means 1. These gain coefficients are variably adjusted by the volume varying means 5.

The operation of the down-mixing device for multi-channel stereo according to the second embodiment of the present invention constructed as above will be described below. In FIG. 2, acoustic signals of a total of 4 channels of L / R main ch, C ch, Sch demodulated from a decoder or the like (not shown) are input to the down mixing means 1. Inside the down mixing means 1, the Cch signal is subjected to volume adjustment by the center channel volume adjusting section 6, and then added to the Lch signal and the Rch signal. The gain coefficient d of the center channel volume adjusting unit 6 is, for example, 0.7. The Lch signal and the Rch signal to which these Cchs are added are adjusted in volume by the Lch volume adjusting section 7 and the Rch volume adjusting section 8, respectively. The gain coefficient a for adjusting the volume is controlled by the volume varying means 5 as described later.

Sc input to the down mixing means 1
The h signal is adjusted in volume by the surround ch volume adjusting unit 9, and then added to the output signals of the Lch volume adjusting unit 7 and the Rch volume adjusting unit 8 described above, and finally downmixing means as a 2ch signal. It is output from 1. These 2ch output signals are used for control amplifier, etc.
It is reproduced by a 2ch speaker arranged in front of the viewer or a 2ch speaker incorporated in the TV (both not shown) via (not shown). The gain coefficient b of the surround channel volume adjusting section 9 is also controlled by the volume varying means 5, as will be described later.

On the other hand, the L / R main ch signals demodulated from a decoder or the like (not shown) are added by the adding means 2 and then input to the music / voice discrimination means 3. The music / speech discriminating means 3 discriminates continuously or discretely on the time axis whether the demodulated acoustic signal is music or voice based on the input acoustic signal, and the discrimination result is sent to the volume varying means 5. introduce. Based on the determination result, the volume varying means 5 sets the above L
If the gain coefficient a of the ch volume adjusting section 7 and the Rch volume adjusting section 8 and the gain coefficient b of the surround channel volume adjusting section 9 are determined to be music, the gain coefficient a is set to an optimum value for music, and the sound is changed to voice. If it is determined, the value is corrected to the optimum value for the voice.

As a concrete correction method of the gain coefficients a and b, for example, the following method can be considered. That is,
The optimum values for music reproduction are a = 1.0 and b = 0.7, and the optimum values for voice reproduction are a = 1.4 and b = 0.3. Then, based on the continuous or discrete discrimination result of the music / speech discriminating means 3, when a and b are discriminated as music (speech) from the current value, they are determined as optimum values for the music (speech). I will gradually correct it so that.

By performing the variable adjustment of the gain coefficient as described above, in the case of voice reproduction, the level of the surround ch signal added to the L / R ch signal becomes smaller than that in normal music reproduction. In the case of music, realistic reproduction can be performed, and in the case of voice, clear reproduction can be performed. Further, if the gain coefficient is variably adjusted little by little as described above, it is possible to avoid the unnaturalness due to a sudden change in the reproduced sound field even in the case of misjudgment that may occur stochastically.

In the above embodiments, 4 ch is assumed as the multi-channel stereo system,
The present invention is not limited to this. For example, the surround channels may be 2 channels for the right rear speaker and the left rear speaker, and a total of 5 ch system may be used. Further, the signal input to the music / speech discrimination means is the added signal of the L / R main channels, but it is not limited to this and may be, for example, a Cch signal.

[0020]

As is apparent from the above embodiment, the multi-channel stereo down-mixing device of the present invention discriminates whether the multi-channel audio signals to be mixed down are music or voice, and mixes based on the discrimination result. Acoustic parameters related to signal processing for down,
In the case of music reproduction, the value is adjusted to a value that can provide a realistic sensation, and in the case of voice, the value is corrected to a value that can ensure a sense of clarity. Therefore, even in 2ch speaker reproduction, optimum sound reproduction for each program source is realized. It becomes possible.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a multi-channel stereo down-mixing device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing the configuration of a multi-channel stereo down-mixing device according to a second embodiment of the present invention.

FIG. 3 is a block diagram of a conventional multi-channel stereo down-mixing device.

[Explanation of symbols]

1 ... Down mixing means, 2 ... Addition means, 3 ... Music / voice discrimination means, 4 ... Parameter changing means, 5 ...
Volume varying means, 6 ... Center channel volume adjusting section, 7
... Lch volume adjusting section, 8 ... Rch volume adjusting section,
9 ... Surround channel volume control section, 10 ... Down mixing section, 11 ... Surround channel volume.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroko Numazu 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Akihisa Kawamura, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. 72) Inventor Mikio Oda 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (2)

[Claims] 1. Downmixing means for mixing down input audio signals of 3 channels or more to output audio signals of 2 channels, and using at least 1 channel of the input audio signals of 3 channels or more A music / voice discrimination means for discriminating whether the input signal is music or voice, and a parameter varying means for changing an acoustic parameter inside the downmixing means based on the discrimination result by the music / voice discrimination means. A down-mixing device for multi-channel stereo, characterized by. 2. The down-mixing means adjusts the volume of the input center channel signal, and adjusts the volume of the center channel, the volume of the input Lch signal, or the volume of the input Lch signal and the center channel. Volume of the Lch signal for adjusting the volume of the signal obtained by adding the output signal of the unit, and the volume of the input Rch signal, or the input signal of the Rch signal and the output signal of the volume adjustment unit for the center channel are added. A volume adjusting unit for Rch that adjusts the volume of the signal and a volume adjusting unit for the surround channel that adjusts the volume of the input surround channel signal are included, and the parameter varying unit determines the determination result of the music / voice determining unit. Based on the center channel volume adjusting section, the Lch volume adjusting section, the Rch volume adjusting section, the surround channel volume The multi-channel stereo downmixing device according to claim 1, wherein the gain of at least one of the adjusting units is changed.