JP2010034700A - Audio signal processing apparatus, speaker system, and television - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an audio signal processing apparatus including a DRC (Dynamic Range Compression) achieving also trouble countermeasures in large volume while preventing atmospheres of various contents from being lost and to provide a speaker system and a television. <P>SOLUTION: In the television, a first level D1 and a second level D2 for regulating a first section, a second section and a third section in input/output characteristics set in a compression part are set to fixed values independently of the setting of a volume value Vol, compression ratios of the first section and the second section occupying most of an audio part of a movie are made different from each other independently of the setting of the volume value Vol, so that a range of the third section in which the compression ratio is changed according to the volume value Vol can be reduced. Thereby, an audio-visual environment having a higher flexibility corresponding to a reproducing condition can be constructed without remarkably losing movie producer's intentions, even when the television is viewed at any volume value Vol. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a compression technique of a dynamic range of an audio signal.

When watching content such as movies on a TV, the soundtrack is too wide for listening in the living room of the home, the volume of the audio signal is too large, the volume is too loud in a loud scene, and the volume is low Then the volume is too low to be heard. By providing DRC (Dynamic Range Compression) to improve this state, the fluctuation range of the volume can be narrowed. Further, DRC is used as a countermeasure against a problem at a high volume. At this time, there is a technique for changing a DRC parameter according to a volume value for adjusting an output volume (for example, Patent Document 1).
JP 2007-104407 A

  By the way, DRC has been used to narrow the volume range as described above, or to take measures against malfunctions at high volumes, and therefore, depending on the input / output characteristics of dynamic range compression, the atmosphere when watching movies is impaired. There was a case where it became a thing.

  The present invention has been made in view of the above-described circumstances, and an audio signal processing apparatus and a speaker apparatus having a DRC that can take measures against malfunctions at high volumes while maintaining the atmosphere of various contents. And to provide television.

  In order to solve the above-described problems, the present invention provides an input means for inputting an audio signal, an amplification means for amplifying and outputting a supplied audio signal at a set amplification factor, and a setting for setting the amplification factor And a compression unit that compresses a dynamic range of the audio signal input to the input unit with an input / output characteristic set so as to change according to an amplification factor set by the setting unit and supplies the audio signal to the amplification unit And the compression means compresses at a first compression rate when the input level of the audio signal input by the input means is less than the first level, and is equal to or higher than the first level. In a range that is less than the second level, compression is performed at a second compression rate that is different from the first compression rate. An input / output characteristic for compressing the dynamic range of the input level of the audio signal is set so that the audio signal is compressed at a third compression rate that is a compression rate determined according to a predetermined amplification rate. An audio signal processing apparatus is provided.

  In another preferred aspect, the input / output characteristics set in the compression means are set by the setting means so that an output level of an audio signal output from the amplification means does not exceed a preset maximum value. The third compression rate is determined according to a set amplification factor.

  In another preferred aspect, the input / output characteristic set in the compression means is input by the input means when the third compression ratio is maximized within a range of compression ratios that can be determined. When the input level of the audio signal is the maximum level, the output level is the maximum level.

  In another preferred embodiment, the input / output characteristic set in the compression means has a third compression ratio when the amplification factor set by the setting device is equal to or less than a preset amplification factor. The compression ratio is determined as the same compression ratio as the second compression ratio, and when the gain is larger than a preset amplification ratio, the third compression ratio is determined so as to achieve high compression as the amplification ratio increases. To do.

  In another preferable aspect, the third compression rate of the input / output characteristic set in the compression unit is determined by the input unit when the amplification rate set by the setting unit is the maximum amplification rate. The output level is determined to be constant even when the input level of the input audio signal changes.

  In another preferred aspect, the first compression rate is determined to be lower than the second compression rate.

  In another preferred aspect, the first compression rate or the second compression rate of the input / output characteristics set in the compression means is determined so that the dynamic range is not compressed or expanded. To do.

  The present invention also provides a speaker device comprising the above-described audio signal processing device and sound emitting means for emitting the audio signal output from the amplifying means.

  In addition, the present invention includes the above-described audio signal processing device, an acquisition unit that acquires a video signal and an audio signal, and a display unit that displays an image related to the video signal acquired by the acquisition unit, and the input An audio signal input to the means is an audio signal acquired by the acquisition means.

  According to the present invention, it is possible to provide an audio signal processing device, a speaker device, and a television having a DRC that can deal with a problem at a high volume while maintaining the atmosphere of various contents.

  Hereinafter, an embodiment of the present invention will be described.

<Embodiment>
The television 1 according to the embodiment of the present invention is a thin television such as a liquid crystal display, a plasma display, and an organic EL display. A configuration of the television 1 will be described with reference to FIG. FIG. 1 is a block diagram showing a configuration of the television 1. Note that the television 1 has a CPU (Central Processing Unit) (not shown), and this CPU controls each part of the television 1.

  The television 1 includes a signal acquisition unit 2, a video display device 10, and a speaker device 20. The speaker device 20 includes a sound emitting unit 21 and an audio signal processing device 30. The video display device 10 includes a video signal input unit 11 and a display unit 12. In addition, the audio signal processing device 30 includes an audio signal input unit 31, a compression unit 32, an amplification unit 33, an operation unit 34, a storage unit 35, and a parameter setting unit 36.

  The signal acquisition unit 2 receives data from a TV tuner, a DVD (Digital Versatile Disc) playback device, or the like, and generates a video signal and an audio signal in accordance with control of a CPU (not shown). The signal and the audio signal are acquired, the video signal is input to the video signal input unit 11, and the audio signal is input to the audio signal input unit 31.

  The video signal input unit 11 outputs the video signal input from the signal acquisition unit 2 to the display unit 12.

  The display unit 12 is a display device having a display surface such as a liquid crystal display, a plasma display, or an organic EL display, and performs display according to the video signal output from the video signal input unit 11.

  The sound emitting unit 21 is a speaker that emits an audio signal output from the amplifying unit 33 of the audio signal processing device 30 described later. The sound emitting unit 21 may have a power amplifier, and may be configured to emit an audio signal amplified by the power amplifier from a speaker. The sound emitting unit 21 may have an external configuration such as an external speaker device. In this case, a connection terminal for connecting the external speaker device is provided, and the audio signal amplified by the amplification unit 33 described later is What is necessary is just to make it supply to a connection terminal.

  The audio signal input unit 31 outputs the audio signal input from the signal acquisition unit 2 to the compression unit 32.

  The compression unit 32 is a DRC or the like that adjusts the dynamic range, and compresses the dynamic range of the audio signal output from the audio signal input unit 31 with the input / output characteristics indicated by the parameters set from the parameter setting unit 36 described later. And supplied to the amplifying unit 33. The input / output characteristics will be described later.

  The amplification unit 33 amplifies the audio signal supplied from the compression unit 32 with an amplification factor set from the operation unit 34 described later, and outputs the amplified audio signal to the sound emission unit 21.

  The operation unit 34 has a volume operation unit that sets a volume value Vol that indicates the volume of sound emitted from the sound emission unit 21. When the user operates the volume operation unit to set the volume value Vol, the amplification unit For 33, an amplification factor corresponding to the volume value Vol is set. Further, the set volume value Vol is output to the parameter setting unit 36. In this example, the volume value can be set stepwise as “0 (silence)”, “1”,... “10 (maximum volume)”, and is set to change by 2 dB per step. . The setting of the volume value Vol is not limited to that performed by the operation unit 34 by the user's operation, but may be performed by an instruction from a CPU (not shown).

  As shown in FIG. 2, the storage unit 35 stores a plurality of parameters indicating input / output characteristics set in the compression unit 32, and each of the input / output characteristics includes each volume value Vol set in the operation unit 34. It is associated. In the example shown in FIG. 2, the input / output characteristics are stored corresponding to each volume value Vol. For example, when the volume value Vol is “1” to “7”, the corresponding input is stored. If the output characteristics are the same, one input / output characteristic may be stored corresponding to the volume value Vol in this range. In addition, since the volume value Vol is “0”, it is in a silent state in the first place, so there is no corresponding input / output characteristic.

  The parameter setting unit 36 reads out a parameter indicating input / output characteristics corresponding to the volume value Vol output from the operation unit 34 and sets the parameter in the compression unit 32.

  Here, an example of the input / output characteristics of the parameters stored in the storage unit 35 will be described with reference to FIG. FIG. 3 is an input / output characteristic diagram showing the relationship between the input level of the audio signal input to the compression unit 32 and the output level of the audio signal output from the compression unit 32. Each of the input / output characteristics stored in the storage unit 35 is shown in FIG. The input / output characteristics corresponding to the volume value Vol are collectively shown.

  The input / output characteristics in this example are set so as not to impair the atmosphere when used when watching a movie. Audio in a movie is roughly classified into dialog (serial), music, and sound effects. The line is set to a relatively low input level, and is generally set to -26 dB to -31 dB. On the other hand, a large sound effect is used for an impressive effect in a specific scene of a movie. In such a case, the input / output characteristics as shown in FIG.

  Details of the input / output characteristics shown in FIG. 3 will be described. C1, C2, C3,..., C6 shown in FIG. 3 each indicate a compression rate, and indicates a slope, that is, an output level differentiated by an input level. Therefore, if the compression rate is “1”, compression is not performed, and the input level change amount and the output level change amount are the same. As the compression ratio becomes smaller than “1”, the dynamic range is compressed so that the change in the output level becomes smaller with respect to the change in the input level. That is, the smaller the compression rate, the higher the compression. On the other hand, as the compression ratio becomes larger than “1”, the dynamic range is extended so that the output level change becomes larger with respect to the input level change.

  In the input / output characteristics shown in FIG. 3, when the input level is less than the minimum level min to the first level D1 (in this example, −25 dB), the compression rate is C1 (“1” in this example). Yes. Therefore, in this input level range (hereinafter referred to as the first section), dynamic range compression / expansion is not performed, and only a gain shift of a shift amount G (10 dB in this example) is performed.

  When the input level is equal to or higher than the first level D1 and lower than the second level D2 (in this example, −10 dB), the compression ratio C2 (in this example, “0.6”) is obtained. Therefore, dynamic range compression is performed in this input level range (hereinafter referred to as the second interval).

  When the input level is equal to or higher than the second level D2 and the maximum level max, the compression rate changes according to the set volume value Vol, and the compression rate C3 (in this example) when the volume value Vol is from “1” to “7”. Is the same as C2, “0.6”). When the volume value Vol is “8”, “9”, “10”, the compression ratios are C4, C5, C6, respectively. In this example, “0.4”, “0.2”, “0”, respectively. Is determined. Therefore, in this input level range (hereinafter referred to as the third section), the compression of the dynamic range is performed so as to achieve higher compression by decreasing the compression rate as the volume value Vol increases. .

  Here, when the volume value Vol that becomes the compression rate C3 in the third section is set, that is, when the compression ratio in the third section is the maximum compression ratio that can be determined, the input level is the maximum level. When it is max, the output level has an input / output characteristic such that it is output at the maximum level max. The threshold value Dth indicates the output level when the input level is the maximum level max and the volume value Vol is “10”. When the volume value Vol is “10”, the compression ratio C6 is “ 0 ”, which is the same as the output level corresponding to the second level D2 in the input / output characteristics. Therefore, in this example, the threshold value Dth is −6 dB.

  When the input / output characteristics are set in the compression unit 32 as described above, the relationship with the output level of the audio signal output from the amplification unit 33 will be described with reference to FIG. FIG. 4 is an input / output characteristic diagram showing the relationship between the input level of the audio signal input to the compression unit 32 and the output level of the audio signal amplified by the amplification unit 33 and output.

  As shown in FIG. 4, when the volume value Vol is “8” or more, the compression level of the third section is reduced to achieve higher compression, and the output level of the audio signal output from the amplifying unit 33 is the maximum. The value Th is not exceeded. This is due to a countermeasure against a problem at a high volume level, and by outputting an audio signal with an output level higher than this, the signal is distorted beyond the amplification capability of the amplification unit 33, and the processing of the sound emission unit 21 at the subsequent stage is performed. This is to prevent deterioration in sound quality by adversely affecting the circuit.

  Here, when the volume value Vol is “10”, the input level when the output level reaches the maximum value Th corresponds to the second level D2. Therefore, if the compression rate C6 is “0” and the input / output characteristics and the compression rate C2 of the first section are determined, the second level D2, the compression rates C3, C4, and C5 are related to the amplification unit 33. It is determined by the relationship with the maximum value Th. That is, on the assumption that the maximum value Th related to the amplifying unit 33 is determined and the compression rate C6 is “0”, the overall input / output characteristics can be defined by the first level D1 and the compression rates C1 and C2. .

  In this way, by determining the input / output characteristics set in the compression unit 32, the following effects can be obtained. In other words, in the first section, it corresponds to the input level of the speech, there is no transient gain fluctuation due to compression, and the movie can be viewed in a state where the speech volume does not fluctuate easily and does not feel strange. Also, since the volume of the dialogue is relatively amplified by the amount of gain shift, it is easy to hear. Further, since the compression rate C1 is determined as “1”, the dynamic range indicated by the input audio signal is not compressed and expanded, and the user can view the dynamic range faithful to the original sound.

  On the other hand, in the third section, which corresponds to the input level of the loud sound effect, even if the set volume value Vol designates the loud sound, a problem such as sound distortion is avoided. be able to. Further, even if the compression rate changes depending on the set volume value Vol, since it is for a sound effect that does not always occur, the sense of incongruity is less.

  In the second section, the compression is performed at a constant compression rate C2 regardless of the setting of the volume value Vol. In particular, for music in the level range of the second section, a natural effect can be obtained and a good reproduction state can be obtained without losing musicality. In addition, by setting different compression ratios in the first section and the second section in this way, it is also possible to reduce the range of the third section in which the compression ratio changes according to the volume value Vol.

  As described above, the television 1 according to the embodiment of the present invention has the first level D1 and the second level that define the first section, the second section, and the third section for the input / output characteristics set in the compression unit 32. The level D2 is set to a constant value regardless of the setting of the volume value Vol, the compression ratios in the first and second sections occupying most of the audio of the movie are varied, and the level D2 is not set according to the setting of the volume value Vol. Therefore, the range of the third section in which the compression rate changes according to the volume value Vol can be reduced. Therefore, it is possible to construct a viewing environment with a higher degree of freedom according to the circumstances on the playback side, without damaging the intention of the movie producer, regardless of the volume value Vol.

  As mentioned above, although embodiment of this invention was described, this invention can be implemented in various aspects as follows.

<Modification 1>
In the above-described embodiment, the television 1 has been described, but the speaker device 20 and the audio signal processing device 30 can also be used as a single device.

<Modification 2>
In the above-described embodiment, in the input / output characteristics, the input level is defined by the first level D1 and the second level D2, and the first interval, the second interval, and the third interval are defined. May be. In this case, the compression rate in each section may be varied so that the compression ratio changes in accordance with the volume value Vol in a section where the input level section is the largest.

  Note that the compression rate may change in accordance with the volume value Vol for a plurality of sections from the higher input level. For example, the lower input level is defined as the first section, and the fifth section is provided so that the compression ratio changes in accordance with the volume value Vol in the fourth section and the fifth section, and the manner of change is made different. do it.

<Modification 3>
In the above-described embodiment, for example, input / output characteristics suitable for viewing a movie are given as an example. However, it may be better to use different input / output characteristics for viewing various contents. Therefore, another example of input / output characteristics will be described with reference to FIGS.

  In the example shown in FIG. 5, the magnitude relationship between the compression rate C1 and the compression rate C2 is reversed compared to the case of the above-described embodiment. As for the second level D2, the compression ratios C3, C4, and C5, as described in the embodiment, the maximum value Th related to the amplifying unit 33 is determined and the compression ratio C6 is “0”. These are determined corresponding to the input / output characteristics of the first section and the compression ratio C2. The input / output characteristics as shown in FIG. 5 are preferably used for content in which a low level of an input audio signal is not often used because the compression rate is set low at a low input level. If the compression rate C2 is set to “1”, the dynamic range compression / expansion indicated by the input audio signal is not performed in the second section, and it is possible to view in the dynamic range faithful to the original sound.

  Further, when the input / output characteristics and the compression rate C2 of the first section are determined as shown in FIG. 6, unlike the input / output characteristics in the embodiment, the compression rate C2 and the compression rate C3 are different. As described above, the compression rate C2 and the compression rate C3 may not be the same depending on the setting. The input / output characteristics as shown in FIG. 6 are used for content that focuses on the output at the low level of the input audio signal because the compression ratio is set so as to extend the dynamic range at a low input level. It is preferable.

  As described above, in the input / output characteristics, the relationship between the compression ratios C1 and C2 and the relationship between the compression ratios C2 and C3 are not limited to the relationships in the embodiment, but may be various relationships depending on the desired output characteristics. Can do. At this time, as in the case of the embodiment, the output level of the audio signal output from the amplifying unit 33 does not exceed the maximum value Th, the compression rate C6 is “0”, the compression of the third section When the rate is the maximum, that is, when the compression rate is C3, when the input level of the input audio signal is the maximum level, the corresponding relationship is such that the output level of the output audio signal is the maximum level. It is desirable.

<Modification 4>
Various input / output characteristics as shown in the modification 3 may be stored in the storage unit 35 in correspondence with the genre of the content. That is, a group of input / output characteristics corresponding to the volume value Vol may be stored corresponding to the genre.

  In this case, an operator for specifying a genre is provided in the operation unit 34, and when specified by the user, genre information indicating the specified genre is transmitted to the parameter setting unit 36. Then, the parameter setting unit 36 identifies an input / output characteristic group corresponding to the genre indicated by the genre information, and, as shown in the embodiment, the input / output characteristic group corresponding to the genre indicated by the genre information is input according to the volume value Vol. The output characteristic may be read and set in the compression unit 32.

  The specification of the genre is not only performed by the operation unit 34, but the signal acquisition unit 2 acquires the genre information together with the video signal and the audio signal, and outputs the genre information to the parameter setting unit 36. It may be set automatically. Further, instead of the genre information, an input / output characteristic group corresponding to the volume value Vol may be acquired and output to the parameter setting unit 36 to be automatically set. At this time, the genre information may be acquired together. If the genre indicated by the acquired genre information and the group of the input / output characteristics are not stored in association with the storage unit 35, May be newly stored in the storage unit 35.

<Modification 5>
In the embodiment described above, the volume value Vol that can be set in the operation unit 34 is a discontinuous value such as “0”, “1”, “2”,..., “10”. It may be something that changes. In that case, for the input / output characteristics stored in the storage unit 35, the parameter may be set as a function represented by the volume value Vol. That is, the compression rates C3, C4, C5, and C6 in the embodiment correspond to Vol = 1 to 7, 8, 9, and 10, but the compression rate in the third section is expressed as C (Vol). You can do it. Even if the volume value Vol is a discontinuous value as in the embodiment, the storage unit 35 may store a parameter indicating the input / output characteristics as a function represented by the volume value Vol.

It is a block diagram which shows the structure of the television which concerns on embodiment. It is explanatory drawing which shows the memory content of the memory | storage part which concerns on embodiment. It is explanatory drawing which shows an example of the input-output characteristic set to the compression part which concerns on embodiment. It is explanatory drawing which shows the relationship between the input level of the audio signal input into the compression part which concerns on embodiment, and the output level of the audio signal output from an amplifier. 10 is an explanatory diagram illustrating an example of input / output characteristics set in a compression unit according to Modification Example 3. FIG. 10 is an explanatory diagram illustrating an example of input / output characteristics set in a compression unit according to Modification Example 3. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Television, 2 ... Signal acquisition part, 10 ... Video display apparatus, 11 ... Video signal input part, 12 ... Display part, 20 ... Speaker apparatus, 21 ... Sound emission part, 30 ... Audio signal processing apparatus, 31 ... Audio signal Input unit 32 ... Compression unit 33 ... Amplification unit 34 ... Operation unit 35 ... Storage unit 36 ... Parameter setting unit

Claims (9)

An input means for inputting an audio signal;
Amplifying means for amplifying and outputting the supplied audio signal at a set amplification factor;
Setting means for setting the amplification factor;
Compression means for compressing the dynamic range of the audio signal input to the input means with input / output characteristics set so as to change according to the amplification factor set by the setting means and supplying the compressed audio signal to the amplification means; Equipped,
When the input level of the audio signal input by the input unit is less than the first level, the compression unit compresses at the first compression rate, and the compression level is equal to or higher than the first level and lower than the second level. In this range, compression is performed at a second compression rate that is different from the first compression rate, and is determined in accordance with the amplification factor set by the setting means at the second level or higher. An audio signal processing device, wherein input / output characteristics for compressing a dynamic range of an input level of the audio signal are set so as to compress at a third compression rate which is a compression rate. The input / output characteristics set in the compression means depend on the amplification factor set by the setting means so that the output level of the audio signal output from the amplification means does not exceed a preset maximum value. The audio signal processing apparatus according to claim 1, wherein the third compression rate is determined. When the input / output characteristics set in the compression means are maximized within a compression rate range in which the third compression ratio can be determined, the input level of the audio signal input by the input means is The audio signal processing device according to claim 1 or 2, wherein when the maximum level, the output level corresponds to the maximum level. The input / output characteristic set in the compression means is such that the third compression ratio is the same as the second compression ratio when the amplification factor set by the setting means is equal to or less than a preset amplification factor. The third compression ratio is determined so as to achieve high compression as the amplification factor increases when the amplification factor is greater than a preset amplification factor. The audio signal processing device according to any one of the above. The third compression rate of the input / output characteristics set in the compression unit is the input level of the audio signal input by the input unit when the amplification rate set by the setting unit is the maximum amplification rate. The audio signal processing device according to any one of claims 1 to 4, wherein the output level is determined to be constant even if the signal changes. The audio signal processing apparatus according to claim 1, wherein the first compression rate is determined to be lower than the second compression rate. The first compression ratio or the second compression ratio of the input / output characteristics set in the compression means is determined so that the dynamic range is not compressed or expanded. The audio signal processing device according to any one of the above. The audio signal processing device according to any one of claims 1 to 7,
A speaker device comprising: sound emitting means for emitting an audio signal output from the amplifying means. The audio signal processing device according to any one of claims 1 to 7,
An acquisition means for acquiring a video signal and an audio signal;
Display means for displaying video related to the video signal acquired by the acquisition means,
The audio signal input to the input unit is an audio signal acquired by the acquisition unit.

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