KR950006847B1 - Volume control device for playback signal - Google Patents

Abstract

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Description

Volume control device for playback signal

1 is a block diagram showing a device for automatically adjusting the volume of a playback signal according to the present invention.

* Explanation of symbols for main parts of the drawings

1: digital signal source 2: delay circuit

3: multiplier 4: envelope detector

5: Lookup Table 6: Digital / Analog Converter

7: microphone 8: amplifier

9: Analog / Digital Converter 10: Envelope Detector

11: envelope detector 12: similarity comparator

The present invention relates to a volume control device for automatically adjusting the signal level of a playback signal output from a CD player (Compact disk player), for example. Particularly, the present invention relates to a signal level, i. It relates to a volume automatic control device.

In general, in the case of an audio device, the user adjusts the playback volume to a desired level by using a volume control switch. By the way, in the case of car audio used in a car, the noise level of the surroundings is changed from time to time depending on the speed of the car and the surrounding environment, so that the user may have to adjust the volume from time to time according to the surrounding environment. However, carelessness due to volume adjustment may cause an accident.

Therefore, recently, the automatic volume control device for automatically adjusting the volume by detecting the ambient noise, that is, the noise level has been introduced.

However, such a volume automatic control device does not adequately respond to a higher or lower volume of the playback signal itself for music such as classical music having a wide dynamic range, and to a relatively high volume playback signal. Also, since the volume is increased to the same level as the playback signal with a small volume, there is a fear that the operation may be disturbed by the excessively loud playback sound.

Moreover, if the microphone is simply used to measure the ambient noise, the microphone measures not only the ambient noise but also the volume of the music to be listened to. Equipment is needed.

Accordingly, the present invention has been made in view of the above circumstances, and provides a device for automatically adjusting the volume of a reproduced signal in which a volume adjustment level can be appropriately changed according to the volume and the amount of the reproduced signal itself in a relatively simple configuration. The purpose is.

An apparatus for automatically adjusting the volume of a reproduction signal according to the present invention for realizing the above object includes a first envelope detecting means for detecting an envelope of a reproduction signal output from an audio signal source, and a second envelope detecting signal sent to a speaker. Envelope detection means, Audio signal input means for inputting the audio signal output to the speaker, Third envelope detection means for detecting the envelope of the signal input to the audio signal input means, Output from the second and third envelope detection means And similarity comparison means for comparing the similarity of the envelope data, and gain adjusting means for adjusting the gain of the reproduction signal based on the similarity data output from the similarity comparison means and the envelope data output from the first envelope detection means. It is characterized by.

According to the present invention having the above-described configuration, the similarity comparing means detects the noise level by comparing the similarity between the signal output through the speaker and the signal sent to the speaker, and the noise level obtained at this time and the signal reproduced and output from the audio signal source The volume adjustment is performed based on the level, so that the volume control can be performed dynamically.

Next, another embodiment of the present invention will be described in detail.

1 is a block diagram showing a device for automatically adjusting the volume of a reproduction signal according to the present invention. In the drawing, reference numeral 1 denotes a digital signal source for outputting a digital reproduction signal, such as a CD player, and 2 is output from a digital signal source. A delay circuit for delaying the digital signal during the processing time by the envelope detector 4 and the lookup table 5, which will be described later, and 7 input an audio signal containing music and ambient noise output through a speaker not shown. A microphone 7, 8 an amplifier 8 for amplifying the signal input by the microphone 7, 9 an analog / digital converter for converting an analog signal output from the amplifier 8 into a digital signal, and 10 Envelope detector for detecting the envelope of the digital signal output from the analog / digital converter 9, 11 is the envelope of the digital reproduction signal output through the delay circuit (2) and multiplier (3) Envelope detector for detecting a, 12 is a similarity comparator for comparing the similarity of the envelope data output from the envelope detector 10 and the envelope detector 11, 4 is the reproduction digital signal output from the digital signal source (1) An envelope detector for detecting an envelope, 5 is a look-up table for supplying a multiplication coefficient to the multiplier 3 based on the envelope data output from the envelope detector 4 and the similarity data output from the similarity comparator 12, and A multiplier which adjusts the gain of the reproduction signal by multiplying the multiplication coefficient supplied from the lookup table 5 to the digital reproduction signal output through the delay circuit 2, and 6 denotes the digital reproduction multiplied by this multiplier 3; It is a digital / analog converter that converts signals into analog signals.

Next, the operation of the automatic volume control device according to the present invention having the above configuration.

When the digital signal is output from the digital signal source 1, this signal is supplied to the multiplier 3 through the delay circuit 2, and the envelope is detected by the envelope detector 4 so that the envelope data is converted into a gain adjustment lookup table ( 5) to be supplied.

At this time, the lookup table 5 stores the multiplication coefficient data in matrix form corresponding to the envelope data output from the envelope detector 4 and the similarity data output from the similarity comparator 12. From 5) the appropriate multiplication factor is supplied to the multiplier (3).

The multiplier 3 multiplies the digital signal data input through the delay circuit 2 by the multiplication factor output from the lookup table 5 to adjust and output the gain of the digital signal.

Subsequently, the digital signal output from the multiplier 3 is converted into an analog signal by the digital / analog converter 6 and then output as an audio signal through a speaker (not shown) and input to the envelope detector 11. The envelope is detected.

On the other hand, the audio signal output through the speaker is detected through the microphone (7), the detected analog signal is converted into a digital signal through the amplifier (8) and the analog / digital converter 9, then the envelope detector ( In 10) the envelope is detected.

Then, the envelope data output from the envelope detectors 10 and 11 is input to the similarity comparator 12. The similarity comparator 12 denotes the envelope data output from the envelope detector 10 as “a”. When the envelope data output from the envelope detector 11 is referred to as “b”, the similarity data between the two signals is determined by detecting the variation amount according to time of (b / a) or (a / b) and the similarity data is output. .

That is, for example, when the noise is small, the amount of variation with time of (b / a) or (a / b) is small, so that the similarity data of a small value is output, and when the noise is large, (b / a) or ( Since the variation amount with time of a / b) becomes large, the similarity data of a large value is output.

The similarity data is supplied to the lookup table 5 and the lookup table 5 multiplies the gain adjustment multiplier 3 based on the similarity data and the envelope data output from the envelope detector 4 as described above. ) Will be supplied.

That is, for example, when the similarity data output from the similarity comparator 12 is a small value, a constant “c” is output to the multiplier 3 regardless of the envelope data output from the envelope detector 4, and the similarity data is output. When the value is large, when the envelope data output from the envelope 4 is small, a larger multiplication factor is output to the multiplier 3 to greatly adjust the signal gain of a small level at which noise may be buried.

Accordingly, the signal level, that is, the volume, can be dynamically adjusted according to the ambient noise level and the volume of the signal output from the signal source 1 according to the above-described processing.

In addition, this invention is not limited to the said Example, It can variously deform in the range which does not deviate from the technical summary of this invention. That is, in the above embodiment, the case is applied to the volume control of the digital signal output from a digital signal source, for example, a CD player, a DCC (Digital Compact Casset) player, or a DAT (Digital Audio Tape). The present invention can be applied to volume control of a signal. In this case, an analog / digital converter for converting an audio signal into a digital signal may be provided. Alternatively, an analog signal processor corresponding to the configuration diagram shown in FIG. 1 may be configured.

As described above, according to the present invention, it is possible to provide an automatic volume control device for the playback signal, which enables the volume control level to be appropriately changed according to the volume and the volume of the playback signal itself in a relatively simple configuration.

Claims (3)

First envelope detecting means (4) for detecting an envelope of a reproduction signal output from the audio signal source (1), second envelope detecting means (11) for detecting an envelope of a signal sent to a speaker, and audio output to a speaker Audio signal input means (7) for inputting a signal, third envelope detection means (10) for detecting an envelope of a signal input to said audio signal input means (7), and said second and third envelope detection means (11) Based on the similarity comparison means 12 for comparing the similarity of the envelope data output from (10), and the similarity data output from the similarity comparison means 12 and the envelope data output from the first envelope detection means (4). And a gain adjusting means (5, 3) for adjusting the gain of the reproduced signal. The apparatus of claim 1, wherein the automatic volume control device processes the playback signal in a digital signal state. 2. The gain adjusting means (5) according to claim 1, wherein the gain adjusting means (5, 3) has a low similarity between the signal output through the speaker and the signal input by the audio signal input means (7) and is output from the audio signal source (1). A volume control device for reproducing signals, characterized in that the gain is increased when the signal level of the signal is low.