WO2000005926A1

WO2000005926A1 - Audio signal controller and reproducing device comprising the same

Info

Publication number: WO2000005926A1
Application number: PCT/JP1999/003882
Authority: WO
Inventors: Eiji Nakatani
Original assignee: Matsushita Electric Industrial Co., Ltd.
Priority date: 1998-07-24
Filing date: 1999-07-19
Publication date: 2000-02-03
Also published as: GB0026959D0; GB2352379B; GB2352379A; DE19983393T1; CN1136759C; CN1308833A; GB2352379B8; GB2352379A8

Abstract

An audio signal controller capable of producing a voice having a clear contour and a sound effect imparting a sound expanse feeling when the source is a stereo movie, capable of localizing the speech at the center of the screen, and exhibiting as good a quality of sound as conventional when the source is music. The controller comprises a surround circuit (1) and band-pass circuits (11R, 11L) each connected to the surround circuit (1) in series for each channel. The characteristics of the circuits (1, 11R, 11L) are changed interlockingly to an on/off state by a controlling section (3). When stereo signals from, for example, a movie source are reproduced, a switch (2) is changed to an on state to turn off the transistor (14R) and to turn on a field-effect transistor (4) by using the controlling section (3). As a result, the music signal with a frequency characteristic that the mid-range is stronger than the other ranges is reproduced from loudspeakers (10R, 10L), thus, producing a voice having a clear contour and a sound effect imparting a sound expanse feeling.

Description

Specification

Audio signal control device and reproducing device having the same

The present invention relates to an audio signal control device for controlling the sound quality of an audio signal in an audiovisual device.

Background art

Conventionally, for stereo audio equipment having a visual appearance, a technique of providing a matrix surround circuit to increase the sound in order to provide a sense of reality has been employed. Fig. 6 shows a stereo audio device equipped with the matrix surround circuit 1. When the switch 2 is turned on, the control unit 3 turns on the field effect transistor 4 to turn on the surround effect. Become. Reference numerals 5 and 6 denote resistors for adjusting the surround effect and capacitors for DC power. The frequency characteristics of the right channel amplifiers 7R, 8R, 9R and the speaker 1OR are as flat as possible, and the frequency characteristics of the left channel amplifiers 7L, 8L, 9L and 10L are as flat as possible. It is a bird.

In addition, there is one that uses a speaker to add voice near the human voice band in order to clarify the lines spoken by the characters. In addition, a passband filter that matches the low-frequency range and the human voice band to the respective frequencies in the audio signal is provided, and the volume of each band is controlled using the result of comparing the output, and the Some have an effect that depends on the scene.

In addition, the DVD (Digital Versatile Disc), which has dramatically improved recording capacity, began to spread, and many movie titles were released. Audio data recorded with audio data is, for example, Dolby Digital

(AC-3) 5.1-channel multi-channel audio data is recorded with audio compression, and when this is reproduced, the front speakers L, R, rear speakers L, R, and center speaker It can be reproduced with six speakers, one of which is a subwoofer, and the surround sound can be heard together with the video. The audio data includes dts (Digital Theater Systems) audio data recorded on a DVD as a 5.1 channel multi-channel audio data in the same way as Dolby AC-3 audio data. Playback is usually performed in the same way as Dolby AC-3.

However, in a matrix surround circuit, if the sound effect is widened while watching a movie with a battle scene, the volume of the dialogue becomes relatively low, making it difficult to hear the dialogue. It tends to be in a retracted position.

Also, in a device with a center speaker, the localization of the sound image shifts toward the center speaker, and it does not match the position of the sound source in the image, giving a sense of incongruity. For example, when a center speaker is installed above the cabinet of a television receiver, the sound image is localized above the image and does not match the image. In addition, in the case of this center-speaker, a center-speaker and an amplifier for driving it are required.

In addition, equipment that uses passband filters and comparators also requires a system to control them, which tends to be expensive and complicated.

Furthermore, since sound quality in movie theaters tends to have many overtone components and is different from sound quality for playing music, in the case of a home-use multifunction device that can play music and a movie with one unit, Problem that movie theater atmosphere cannot be reproduced by playback There is.

In addition, Dolby AC-3 and dts audio data playback required six speakers. Disclosure of the invention

The present invention uses a simple circuit configuration and two loudspeakers of stereo, and in a stereo movie source, a sound with a sharp outline and a sound effect with a sense of spaciousness that can be obtained in a movie theater can be obtained. The purpose of the present invention is to provide a speech signal control device that achieves positional matching with the image by localizing the dialogue in the center of the music source and obtaining the same sound quality as that of the conventional music source.

Dolby AC-3 or dts audio data and multi-channel audio data recorded together with video data are played back on a DVD, and 5.1 channels are downmixed and output using stereo 2 speed. It is another object of the present invention to provide a reproducing apparatus capable of outputting the same signal in the same manner as well as automatically switching the surround circuit and the band-pass circuit to the ON state by discriminating the multi-channel. In order to achieve these objects, an audio signal control device according to the present invention is a two-channel audio signal control device having a surround circuit, comprising: a surround circuit capable of switching a surround effect between an on state and an off state; The bandpass on state, in which the middle frequency of the audio signal frequency band is output with a higher gain than the low and high frequencies, and the bandbus off state, in which the frequency characteristics are flat from low to high, are installed in the channel. A possible band-pass circuit, and a control unit that switches the surround circuit and the band-pass circuit between an on state and an off state in cooperation with each other are provided. According to the present invention, by installing a simple circuit configuration and two stereo speakers on both sides of a TV monitor, a stereo movie source has a sound with a sharp outline and a sense of spaciousness that can be obtained in a movie theater. A sound effect is obtained, and the dialogue is localized at the center of the image to achieve a positional match with the image.

A voice signal control device is obtained.

Also, the audio signal control device of the present invention has a surround circuit.

A surround sound circuit that can switch the surround effect between the on state and the off state, and a sound signal control device that is installed in each channel to compare the middle band of the sound signal frequency band with the low band and the high band A bandpass circuit capable of switching to a bandpass on state for outputting at a low gain and a bandpass off state with flat frequency characteristics from a low band to a high band, and an electro-acoustic converter connected to the output of each channel. The control unit switches between the on-state and the off-state by interlocking the surround circuit and the band bus circuit with high-speed electric-to-acoustic conversion of the middle range more efficiently than the low range and the high range. It is characterized by.

Specifically, it is characterized in that the middle range of the audio signal frequency band is set to a band of 400 Hz to 7 kHz.

Also, a reproducing apparatus of the present invention includes any one of the above-described audio signal control apparatuses, and reproduces audio data from a recording medium on which audio data is recorded together with the video data. A control unit configured to interlock the surround circuit and the band bus circuit on and off based on the audio data read from the recording medium by the reproduction unit; Characterized in that it is configured to switch to a state. In addition, the control unit, when determining that the audio data is multi-channel audio data that has been voice-compressed, performs control of the surround circuit. And the band pass circuit is switched to an on state in conjunction with the band pass circuit. '

Further, the multi-channel audio data is Dolby Digital (AC 3) audio data or dts audio data. Also, the reproducing apparatus of the present invention is a reproducing apparatus capable of reproducing a DVD in which a multi-channel audio data is recorded together with at least a video data as a recording medium, wherein a disc of the recording medium is a DVD or another type. A disc discriminating means for discriminating whether the disc is a disc, a decoder for extracting multi-channel data from the recording medium and downmixing and outputting the data to two channels regardless of the number of channels of the original data, Determining means for determining the type of multi-channel audio data, a surround circuit capable of switching a surround effect between an on state and an off state, and a low frequency band in the middle of an audio signal frequency band interposed in each channel. And the bandpass-on state that outputs with a higher gain than in the high range, and the frequency characteristics are flat from low to high A band-pass circuit capable of switching to an active band-pass off state; and a control unit for switching the surround circuit and the band-pass circuit to an on-state and an off-state in conjunction with each other. When the data is determined to be data, the surround circuit and the band pass circuit are switched to an ON state in conjunction with each other. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a configuration diagram of a (first embodiment) audio signal control device of the present invention,

FIG. 2 is a frequency characteristic diagram of the band bus circuit of the embodiment,

FIG. 3 is a conceptual diagram of the acoustic frequency characteristics of the speaker output according to the second embodiment of the present invention. FIG. 4 is a configuration diagram of a reproducing apparatus according to (Embodiment 3) of the present invention, FIG. 5 is a flowchart of a control unit of the embodiment,

FIG. 6 is a configuration diagram of a conventional audio device having a surround circuit. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to FIGS.

Note that components having the same functions as those in FIG. 6 showing the conventional example are denoted by the same reference numerals and described.

(Embodiment 1)

FIG. 1 shows an audio signal control device according to the first embodiment of the present invention. Since the configuration of the right channel and the left channel is the same, the right channel will be described as an example.

A band-pass circuit 11 R is provided at a stage preceding the matrix surround circuit 1. This bandpass circuit 11 R is connected to an amplifier 7 R by a first feedback circuit 12 composed of a resistor and a capacitor for a high frequency cut, and a second feedback circuit composed of a resistor and a capacitor for a low frequency cut. The feedback circuit 1'3 is connected, and the bandpass characteristic is switched by turning on / off the transistor 14R.

FIG. 2 shows the frequency characteristics of the bandpass circuit 11R.

In the band-pass off state where the transistor 14R is turned off, the frequency characteristic shows a flat frequency characteristic from the low band to the high band as shown by the solid line 15, and in the band-pass on state where the transistor 14R is turned on. As shown by the dashed line 16, the mid-range centered at 1 kHz is output with a higher gain by +5 dB than the low-range and high-range.

Specifically, as shown in Fig. 2, in the bandpass on state, the frequency response from the low band to the high band in the bandpass off state is 1 kHz compared to the flat frequency response. At z, the gain is increased by 5 dB, and the bandwidth with the gain increased by 3 dB from the flat frequency characteristic in the band bus off state has a lower limit frequency of 400 Hz and an upper limit frequency of 7 kHz. The frequency characteristic of the bandpass circuit 11R is such that the middle range of 400 Hz to 7 kHz is output with a higher gain than the low range and the high range.

The turning on / off of the transistor 14 R is executed by the control unit 3 which turns on / off the surround effect.

The control unit 3 is configured as follows.

When the switch 2 is turned off as a normal music signal playback state, the field effect transistor 4 is turned off, the surround effect of the matrix surround circuit 1 is turned off, and the transistor 14 R is turned off. The frequency characteristic of the bandpass circuit 11 R shows a flat frequency characteristic shown by the solid line 15. Accordingly, the music signal input to the amplifier 7R is amplified in a flat band from low to high frequencies, and is acoustically converted by the speaker 10R with the same frequency characteristics.

When playing a visual stereo signal such as a movie source, when switch 2 is turned on, the field effect transistor 4 is turned on, the surround effect of the matrix surround circuit 1 is turned on, and the transistor 1 is turned on. 4R is turned on, and as shown by the broken line 16 in the frequency characteristic of the bandpass circuit 11R, only the middle band is output with a high gain of 5 dB. Therefore, the bandpass circuit 11 R increases the harmonic content of explosions and bullet sounds in dialogue and movie battle scenes, resulting in a cinema-like sound with a clearly defined sound. It sounds like the sound image is localized in front of the listener located in front of the center of the speaker.In the battle scene, the sound quality is powerful, and the surround effect is applied by the matrix surround circuit 1, but the dialogue is drawn deep into the screen. position The sound is localized without being localized in the image, and the sound is localized according to the image. The sound field is expanded for the above-mentioned listeners, and the explosive sound and the sound of the evening fall are impressive.

As described above, according to the present embodiment, the simple circuit configuration and the two stereo powers are installed on both sides of the TV monitor, so that a stereo movie source has a sharp outline as obtained in a movie theater. And the effect sound with a sense of spaciousness is obtained, and the dialogue is localized at the center of the image to achieve positional matching with the image. It is.

(Embodiment 2)

Embodiment 2 differs from Embodiment 1 in the frequency characteristics of the speakers 10R and 10L and the frequency characteristics of the bandpass circuits 11R and 11L. Others are the same as (Embodiment 1).

It is preferable that the speakers 10 R and 10 L of (Embodiment 1) have a frequency characteristic that is as flat as possible from low to high frequencies. As shown by the broken line 17 in FIG. 3, the acoustic frequency characteristic of 10 L is converted from electric to acoustic in the middle band around 1 kHz with higher efficiency than the low band and the high band.

The frequency characteristics of the bandpass circuits 11 R and 11 L are adjusted so that the middle band centered at 1 kHz is output with a lower gain than the low band and high band as shown by the broken line 18 in FIG. 1, The constants of the capacitors and resistors of the second feedback circuit 12 and 13 are changed.

With this configuration, when a normal music signal is reproduced, the control unit 3 turns on the transistor 14R and turns off the field effect transistor 4. At this time, the music signal that enters the amplifier 7R is output at a lower gain in the middle range than in the low and high ranges, but the acoustic frequency characteristics of the single speaker 10R are high-efficiency in the middle range. The acoustic frequency coming out of the speaker 10R to convert The characteristic is a flat composite frequency characteristic from low to high as shown by the solid line 19 in FIG.

When playing a visual stereo signal such as a movie source, switch 2 is turned on and control unit 3 turns off transistor 14 R and field effect transistor 4 to turn on the music signal. Comes out of the speakers 10 R and 10 L with the frequency characteristic raised by 5 dB.

This increases the explosion in dialogue and movie combat scenes and the harmonic growth of bullet sounds, resulting in a cinema-like sound with a clearly defined sound. The sound is localized in front of the player, and the sound quality is powerful in the battle scene. In addition, the surround effect is applied by the matrix surround circuit 1, but the dialogue of the dialogue is not located at the position recessed in the screen, but the sound is localized according to the image, and the sound field spreads to the listeners mentioned above. At the same time, the explosive sound and the sound of the evening evening are impressive.

In this way, by installing a simple circuit configuration and two stereo speakers on both sides of the TV monitor, the stereo movie source has a sharp outline and a sense of spaciousness that can be obtained in a movie theater. Sound effects can be obtained, and the dialogue is localized at the center of the image to achieve positional matching with the image. In addition, sound quality similar to that of conventional music sources can be obtained.

(Embodiment 3)

4 and 5 show (Embodiment 3).

FIG. 4 shows a recording / reproducing apparatus having the audio signal control apparatus according to the first embodiment. Although the switch 2 is manually operated in the first embodiment, such a manual operation is not required in the third embodiment.

Note that the same components as those in (Embodiment 1) will be described with the same reference numerals. The recording / reproducing apparatus shown in FIG. 4 uses DVD, VI DEO- A device capable of reproducing an optical disc 20, such as a CD (hereinafter, referred to as a VCD) and a CD-DA. VCD and CD—DA is a CD standard with a common physical structure, and the collective term for both is CD.

The recording surface of the optical disk 20 is irradiated with light through an objective lens built in the optical pickup 22 to the optical disk 20 which is driven to rotate by the spindle motor 21, and the reflected light from the recording surface is detected. Read out the information stored in 20.

The detection signal of the optical pickup 22 is amplified by the RF amplifier 23, and the servo / disk discriminating means 24 discriminates from the output signal of the RF amplifier 23 whether the optical disc 20 is DVD or CD, and Controls focus control of pickup 22, tracking servo, and spindle servo of spindle motor 21.

A decoder 25 has an audio decoder 26 together with a video decoder (not shown). When the audio data input from the RF amplifier 23 is multi-channel audio data, the audio decoder 26 downmixes and outputs as an L, R 2-channel stereo signal. Here, in the case where the disc is a DVD in the above-described discrimination of the decoder 25, in order to determine what kind of audio data is recorded together with the video data, the data input to the audio decoder 26 is used. This is done by reading the evening into the control unit 27 and determining the identification code of the control information recorded on the DVD from the read information. That is, the type of the recording method of the audio compression of MPEG 2 audio data, Dolby AC-3 audio data, and dts audio data is determined.

The data of each of the left and right channels, which are down-mixed into two channels from the audio decoder 26, are input to the band-pass circuits 11R and 11L. Is done.

The bandpass circuits 1 1 R and 1 1 L provide a band pass on state in which the output of the audio decoder 26 is output with a higher gain in the middle of the audio signal frequency band than the low and high bands, and a low pass It can be switched to a band pass off state that outputs with flat frequency characteristics from to the high frequency range.

The outputs of the bandpass circuits 11 R and 11 L are input to the matrix surround circuit 1. The matrix surround circuit 1 is configured to be switchable between an on state in which the output of the bandpass circuits 11 R and 11 is applied with a surround effect and an off state in which the output is applied without the surround effect.

The output of the bandpass circuit 11 R via the matrix surround circuit 1 is reproduced by the speaker 10 R via the amplifier 9 R, and the output of the band bus circuit 11 L via the matrix surround circuit 1 Is reproduced by the speaker 10L via the amplifier 9L.

The control unit 27 collects disc discrimination result information with respect to the servo / disc discriminating means 24 and performs reproduction control on the reproduction of the optical disc 20, and controls the decoder 25 as described above. The type of audio data is determined by determining the identification code of the control information recorded on the DVD from the read information, and the audio data decoding method is set based on the determination of the recording method. R, 11 L and the matrix surround circuit 1 are turned on / off by the control described later, and the above-mentioned on / off state is displayed on the display unit 28. Further, the control unit 27 is configured to collect pressing information of an on-switch and an off-switch (not shown) of the operation unit 29 and perform switching between the band-pass circuits 11 R and 11 L and the matrix surround circuit 1. .

Here, when the optical disk 20 is set, the servo / disk discriminating means 2 Numeral 4 is for rotating the optical disc 20 by the spindle motor 21 and irradiating light through the built-in objective lens by the optical pickup 22 to detect the reflected light from the recording surface, and the output amplified by the RF amplifier 23 Then, the optical disc 20 is distinguished into a DVD and a CD, and the discrimination result is output to the control unit 27.

The output of the RF amplifier 23 is input to the decoder 25, and when the optical disk 20 is a DVD, the input data is read from the audio decoder 26 to the control unit 27, and the read information is recorded on the DVD. The type of the recorded recording method is determined by determining the identification code of the control information. The control unit 27 sets the decoding method in the audio decoder 26 based on the result of the discrimination of the recording method. Then, the audio decoder 26 whose decoding method is set by the control unit 27 downmixes the output of the RF amplifier 23 in the case of multi-channel, and decodes it into a 2-channel stereo audio signal. The output of the audio decoder 26 is input to each of the band-pass circuits 11 R and 11 L. When the output is set to ON by the control unit 27 described later, the output of the audio decoder 26 is Outputs the middle of the signal frequency band with a higher gain than the low and high bands. When set to off, the output of the audio decoder 26 is output with a flat frequency characteristic from the low band to the high band of the audio signal frequency band. The outputs of the bandpass circuits 11 R and 11 L are input to the matrix surround circuit 1, and a surround effect is applied to the output of the bandpass circuit when the output is turned on by the control section 27 described later. Output. When set to off, the bandpass circuits 11R and 11L are output without any surround effect.

FIG. 5 shows a processing routine for controlling the band-pass circuits 11 R and 11 L and the matrix surround circuit 1 by the control unit 27.

In step S 101, the control unit 27 determines that the servo / disk It is determined whether the optical disk 20 is a DVD from the optical disk determination information obtained from the stage 24. If the optical disc 20 is a CD, then the routine from step S102 to step S104 is executed.

In step S102, the bandpass circuits 11R and 11L and the matrix surround circuit 1 are turned off. In step S103, the display section 28 displays the OFF state. In step S104, it is detected whether or not the on-switch of the operation section 29 is operated, and if not, the steps S102 and S103 are repeated. If it is detected in step S104 that the on-switch of the operation unit 29 has been operated, the routine from step S105 to step S107 is executed.

In step S105, the bandpass circuits 11R and 11L and the matrix surround circuit 1 are turned on. In step S106, the display section 28 displays the ON state. In step S107, it is detected whether or not the off switch of the operation unit 29 is operated, and if not, steps S105 and S106 are repeated. If it is detected in step S107 that the off switch of the operation unit 29 has been operated, the process returns to step S102.

On the other hand, if it is determined in step S101 that the data is DVD, then in step S108, it is determined from the stream ID analyzed by the decoder 25 whether the recording method is AC-3.

If it is determined in step S108 that the recording method of the optical disk 20 is AC-3, the routine from step S105 to step S107 is executed, and the bandpass circuit 111 is executed. R, 11 L and matrix surround circuit 1 automatically switch on.

In step S108, the recording method of the optical disk 20 must be AC_3. If it is determined, in step S109, it is determined whether the recording method is dts from the stream ID analyzed by the recording method determination unit 25.

If it is determined in step S109 that the recording method of the optical disk 20 is dts, the routine of steps S105 to S107 is executed to execute the bandpass circuit 11R, 1. 1 L and matrix surround circuit 1 power Automatically switched on.

If it is determined in step S109 that the recording method of the optical disk 20 is not dts, the routine from step S102 to step S104 is executed, and the band-pass circuit 11 R, 1 1 L and matrix surround circuit 1 power S Automatically switched off.

With this configuration, if it is determined that the disc 20 is a DVD and the audio data is recorded in AC-3 or dts, the band bus circuits 11 R and 11 L and the matrix are automatically determined. By turning on the surround circuit 1 S and turning on the display 28, the sound output from the two-channel loudspeaker, despite the sound output from the two-channel loudspeaker, can be obtained with a clearly defined sound. A spacious sound effect can be obtained.

If the disc 20 is a CD-DA or VCD or a DVD but the recording format is MPEG2, the display unit 28 will display OFF and the matrix surround circuit 1 and band By turning off the pass circuits 11 R and 11 L, it is possible to obtain the conventional sound quality for reproducing the audio recording information of the optical disc 20.

If the user wishes to change the setting based on the display of 〇N or 〇FF displayed on the display unit 28, the user presses the ON switch or OFF switch of the operation unit 29 to perform the operation. The settings of the Rix surround circuit 1 and the band pass circuits 11 R and 11 L can be arbitrarily changed. As described above, according to the present invention, a surround circuit and a band-pass circuit are provided in each channel in series, and the characteristics of both circuits are switched between the on state and the off state by the control unit in conjunction with each other. By installing a simple circuit configuration and two loudspeakers on both sides of the TV monitor, the stereo cinema source can obtain a sharp outline sound and a spacious sound effect that can be obtained in a movie theater. In addition, the dialogue can be localized at the center of the image to achieve positional matching with the image, and a two-channel stereo audio signal control device that can achieve the same sound quality as a music source can be realized. It is.

If it is determined that the audio data recorded on the recording medium is recorded as Dolby AC-3 or dts multi-channel audio data, the surround circuit and band pass circuit should be turned on automatically. A playback device that can produce a sound with a sharp contour and a spacious sound effect that can be obtained in a movie theater without any operation, despite the sound output from a two-channel speaker. Can be realized.

In addition, when recorded as multi-channel audio data, the surround sound circuit and band pass circuit are automatically turned off, so that the same sound quality as that of reproducing the sound recording information can be obtained. .

Claims

Range of request

1. A two-channel audio signal control device having a surround circuit, wherein a surround circuit capable of switching a surround effect between an on state and an off state;

A band bus on state in which the middle frequency of the audio signal frequency band is output with a higher gain compared to the low and high frequency bands, and a band pass off state in which the frequency characteristics are flat from low to high frequencies. A switchable band-pass circuit, and a control unit that switches the surround circuit and the band-pass circuit between an on state and an off state in conjunction with each other.

An audio signal control device provided with.

2. A two-channel audio signal control device having a surround circuit, wherein a surround circuit capable of switching a surround effect between an on state and an off state;

A bandpass on state, in which the middle frequency of the audio signal frequency band is output with a lower gain than the low and high frequencies, and a bandpass off state, in which the frequency characteristics are flat from low to high, interposed in each channel A switchable band-pass circuit, a speaker connected to the output of each of the channels to perform electro-acoustic conversion, and perform electro-acoustic conversion with a higher efficiency in the middle range than in the low and high ranges, and the surround circuit. A control unit for interlocking the band-pass circuit to switch between an on state and an off state;

An audio signal control device provided with.

3. Set the middle range of the audio signal frequency band to a band of 40 OHz to 7 kHz. The audio signal control device according to claim 1 or 2.

4. A playback device that has the audio signal control device according to claim 1 or 2 and that plays back audio data from a recording medium on which audio data is recorded together with video data,

A reproducing unit for reproducing the audio data read from the recording medium,

The control unit is configured to switch the surround circuit and the band-pass circuit between an on state and an off state based on audio data read from a recording medium by a reproducing unit.

Playback device.

5. When the control unit determines that the audio data is audio-compressed multi-channel audio data, the control unit switches the surround circuit and the band-pass circuit to an on state in conjunction with each other. The playback device according to claim 4, wherein the playback device is configured as follows.

6. Multi-channel audio data is Dolby Digital (AC-3) audio data or dts audio data

The playback device according to claim 5.

7. A playback device capable of playing back a DVD in which a multi-channel audio data is recorded together with at least video data as a recording medium,

Disk determination means for determining whether the recording medium disk is DVD or any other disk;

Extract multi-channel audio from the recording medium and save the original data A decoder that downmixes and outputs two channels regardless of the number of evening channels,

Determining means for determining the type of the extracted multi-channel audio data;

A surround circuit that can switch the surround effect between an on state and an off state,

A band pass-on state in which the middle frequency of the audio signal frequency band is output with a higher gain compared to the low and high frequencies, and a band bus off state in which the frequency characteristics are flat from the low to high frequencies. A switchable band-pass circuit, and a control unit that switches the surround circuit and the band bus circuit to an on state and an off state in conjunction with each other,

The control unit is configured to link the surround circuit and the bandpass circuit to an on state when determining that the audio data is a multi-channel audio data.

Playback device.