JP2000311446A - Circuit and method for automatic sound adjustment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the circuit and method which automatically calculate the difference in sound volume level of a recorded sound at any time and varies it to proper sound volume when compressed sound data sent out by satellite broadcasting or ground wave digital broadcasting are restored to PCM data. SOLUTION: The automatic sound adjusting circuit is equipped with a variable resistor 1 which generates an increase/decrease decision signal when the sound volume is increased or decreased, a channel circuit 2 which generates a channel number signal selected when a program is selected, an input control circuit 3 which controls the input of a compressed sound data signal, the volume increase/decrease decision signal, and a channel number signal, a computing element 4 which restores the compressed sound data to PCM data and amplifies the PCM data, a memory 5 which holds information needed for the operation of the computing element and stores and holds the threshold and amplification factor of the sound volume level, a DAC circuit 6 which converts the PCM data into an analog sound signal, and an amplifier circuit 1 which amplifies the signal from the DAC circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention restores compressed audio data transmitted in satellite broadcasting or terrestrial digital broadcasting into PCM data, and converts the PCM data into DAC data.
The present invention relates to an automatic audio adjustment circuit and an automatic audio adjustment method for converting an audio to an appropriate volume.

[0002]

2. Description of the Related Art In a conventional automatic volume control circuit, a volume control is only changed and adjusted once for each source of a sound source. For example, JP-A-07-04
The automatic volume control circuit described in 6686 will be described with reference to FIG. 6. The level detection circuit 22 detects the level of a signal provided from a plurality of music sources, and the level detection circuit 22 for reproducing the plurality of music sources. A volume memory key 23 for setting a desired volume level, a RAM 24 for recording the volume level set by the volume memory key 23, and a plurality of music sources based on the volume levels recorded in the RAM 24. With a configuration including volume level means for controlling the volume when a signal is reproduced to the desired volume level, an output of a desired volume level can be obtained regardless of the level of the signal level supplied from the music source. become.

[0003]

However, this prior art has the following problems. The first problem is that in the case where the sound source does not change and the content such as a song changes, the volume volume is not automatically adjusted in this configuration, and the one listening to the volume volume must adjust it.
The reason is that the volume is not dynamically controlled by constantly monitoring PCM audio data such as music. The second problem is that when the volume is low, the volume is not amplified to an appropriate level, and when the volume is high, the sound is output until the sound is broken. The reason is that the volume is fixed for each sound source, so that the above-described problem occurs. The third problem is that noise may be added to the output speech. The reason is that noise is more likely to be mixed into the analog audio data than to perform amplification processing on the PCM data because the amplification processing is performed on the analog audio data.

The present invention provides an automatic audio adjustment circuit and an automatic audio adjustment method that solve the above problems.

[0005]

SUMMARY OF THE INVENTION An automatic audio adjustment circuit and an automatic audio adjustment method according to the present invention use compressed audio data transmitted in satellite broadcasting, digital terrestrial broadcasting, or the like as a P-type audio signal.
When the CM data is restored, the difference in the volume level recorded by the channel or the program is automatically calculated at any time and changed to an appropriate volume. By decompressing the compressed audio data into PCM data, PCM data for a certain period can be obtained. By calculating the average value of the restored PCM data, the average volume level for the certain period is determined. When this average volume level falls below a predetermined value (volume level threshold), a certain value (amplification factor) is applied to the PCM data obtained by the restoration.
To amplify the PCM data. By sending the PCM data thus amplified to the DAC, the sound volume becomes appropriate. If the average volume level exceeds the volume level threshold, it is determined that the volume is high, no operation is performed on the restored PCM data, and the PCM data is directly sent to the DAC. Will be transferred. In addition to these processes, the threshold of the volume level is recorded in the memory in association with the channel or the program, so that the threshold of the volume level of each channel or each program can be immediately obtained. Threshold,
By chaining the increase and decrease of the amplification factor, an appropriate volume suitable for the characteristics of the listener is provided. As a result, programs and channels having different recording levels are automatically adjusted to a comfortable volume.

According to the first aspect of the present invention, a volume for generating an increase / decrease determination signal when the volume is increased / decreased, a channel circuit for generating a channel number signal selected when a program is selected, and compressed audio data An input control circuit that controls each input of a signal, a volume increase / decrease determination signal, and a channel number signal; an arithmetic unit that restores compressed audio data to PCM data or performs amplification processing on the PCM data; A memory for holding necessary information and for storing and holding a threshold and an amplification factor of a volume level, and a DAC for converting the PCM data into an analog audio signal
A circuit and an amplifier circuit for amplifying a signal from the DAC circuit, wherein the input control circuit inputs compressed input audio data and records the compressed input audio data in the memory via the arithmetic unit; The arithmetic unit takes out the compressed audio data recorded in the memory, restores it to PCM data, returns it to the memory, and records it again. The arithmetic unit adds the restored PCM data and outputs the added PCM data. Divide by the number of data to obtain the average value of the PCM data, the arithmetic unit compares the average value with the threshold of the volume level for each channel in the memory, and calculates the average value of the PCM data from the threshold of the volume level. When the volume level was large, the volume level of the PCM data was determined to be appropriate and no arithmetic processing was performed, and the average value of the PCM data was smaller than the volume level threshold. In this case, it is determined that the volume level of the PCM data is low, the amplification of the PCM data is performed by multiplying by the amplification factor for each channel in the memory, and the computing unit compares the PCM data with the threshold value. The data is transferred to a DAC circuit at regular intervals determined by the frequency of the PCM data, and the amplifier circuit has various means for amplifying an analog audio signal generated by digital-to-analog conversion by the DAC circuit. And

According to a second aspect of the present invention, in the automatic audio adjustment circuit according to the first aspect, when starting the automatic audio adjustment circuit, a threshold and an amplification factor of a volume level necessary for automatically adjusting the volume. In this case, an initial value is set in advance, and automatic voice adjustment is started.

According to a third aspect of the present invention, there is provided a volume for generating an increase / decrease determination signal when the volume is increased / decreased, a channel circuit for generating a channel number signal selected when a program is selected, and compressed audio data. An input control circuit that controls each input of a signal, a volume increase / decrease determination signal, and a channel number signal; an arithmetic unit that restores compressed audio data to PCM data or performs amplification processing on the PCM data; A memory for holding necessary information and for storing and holding a threshold and an amplification factor of a volume level, and a DAC for converting the PCM data into an analog audio signal
An automatic audio adjustment circuit including a circuit and an amplifier circuit for amplifying a signal from the DAC circuit, wherein the channel circuit generates a channel number signal selected when a program is selected; The number signal is input and transferred to the arithmetic unit, and the arithmetic unit discards the compressed audio data and the restored PCM data currently recorded in the memory, while the threshold of the volume level and the amplification factor are The present invention is characterized in that a channel switching process is performed in which the compressed data of the newly selected channel is stored in a memory via an input control circuit and an arithmetic unit, and is stored in the memory.

According to a fourth aspect of the present invention, a volume for generating an increase / decrease determination signal when the volume is increased / decreased, a channel circuit for generating a selected channel number signal when a program is selected, and compressed audio data An input control circuit that controls each input of a signal, a volume increase / decrease determination signal, and a channel number signal; an arithmetic unit that restores compressed audio data to PCM data or performs amplification processing on the PCM data; A memory for holding necessary information and for storing and holding a threshold and an amplification factor of a volume level, and a DAC for converting the PCM data into an analog audio signal
In the automatic audio adjustment circuit including a circuit and an amplifier circuit for amplifying a signal from the DAC circuit, the volume generates a volume increase / decrease determination signal according to the increase / decrease, and the input control circuit inputs the volume increase / decrease determination signal. Then, when the volume increase / decrease determination signal indicates that the volume is increasing, the arithmetic unit increases the amplification factor used for the operation and lowers the threshold value of the volume control. It is characterized in that a volume increase / decrease process is performed in which the amplification factor used is lowered and the threshold value of the volume control is raised.

According to a fifth aspect of the present invention, a volume for generating an increase / decrease determination signal when the volume is increased / decreased, a channel circuit for generating a channel number signal selected when a program is selected, and compressed audio data An input control circuit that controls each input of a signal, a volume increase / decrease determination signal, and a channel number signal; an arithmetic unit that restores compressed audio data to PCM data or performs amplification processing on the PCM data; A memory for holding necessary information and for storing and holding a threshold and an amplification factor of a volume level, and a DAC for converting the PCM data into an analog audio signal
The automatic audio adjustment method in the automatic audio adjustment circuit including a circuit and an amplifier circuit for amplifying a signal from the DAC circuit includes the steps of: inputting compressed input audio data to the input control circuit; A process of recording in the memory, extracting compressed audio data recorded in the memory, restoring it to PCM data, returning to the memory and recording again, adding the restored PCM data, and adding the added PCM data. Calculating the average value of the PCM data by dividing by the number of data of the data; comparing the average value with the threshold of the volume level for each channel in the memory; Is larger, the volume level of the PCM data is determined to be appropriate, and no arithmetic processing is performed. If smaller, the volume level of the PCM data is determined to be smaller, was carried out the steps of performing amplification of the PCM data by multiplying the amplification factor of each channel in the memory, the comparison processing between the threshold PC
A step of transferring the M data to the DAC circuit at regular intervals determined by the frequency of the PCM data; and a step of the amplifier circuit amplifying an analog audio signal generated by the DAC circuit by performing digital-to-analog conversion. It is characterized by having.

[0011]

Embodiments of the present invention will now be described with reference to the drawings. Referring to FIG. 1, the automatic volume control circuit has the following configuration. There is a volume 1 for generating an increase / decrease determination signal when the volume is increased / decreased, and a channel circuit 2 for generating a selected channel number signal when a program is selected. Then, there is an input control circuit 3 for controlling each input of the compressed audio data signal, volume increase / decrease determination signal, and channel number signal. Further, there is an arithmetic unit 4 for restoring the compressed audio data to PCM data and for amplifying the PCM data, and the arithmetic unit 4 is connected to a memory 5 necessary for the arithmetic operation. The memory 5 is not only used at the time of calculation, but also stores and holds the threshold value and the amplification factor of the volume level. There is a DAC circuit 6 for converting PCM data, which is digital data, into an analog audio signal.
The AC circuit 6 is connected to an amplifier circuit 7 for amplifying the signal since the signal from the DAC circuit 6 does not have a sound volume that can be heard. The loudspeaker 8 is connected to the amplifier circuit 7 so that the loudspeaker 8 produces sound that can be actually heard by the ear. The input control circuit 3, the arithmetic unit 4, and the DAC circuit 6 are connected by a single bus, and each connected circuit can exchange PCM data and the like.

Next, the operation of the circuit of FIG. 1 will be described with reference to FIGS. 1 and 2 along the flow of data processing.
First, the compressed audio data is recorded in the memory 5 via the input control circuit 3 and the arithmetic unit 4 (step S1). Here, the arithmetic unit 4 retrieves the compressed audio data from the memory 5, restores the compressed audio data to PCM data, and returns to the memory 5, thereby restoring all the compressed audio data (step S2). Then, all the restored PCM data are added, and the sum is divided by the number of PCM data to obtain the PCM data.
An average value of the M data is obtained (step S3). This average value is compared with the threshold of the volume level for each channel in the memory (steps S4 and S5). When comparing for the first time, there is no threshold. If there is no threshold, an initial value is set in advance and compared with that value. When the average value of the PCM data is larger than the threshold value of the volume level, it is determined that the volume level is appropriate, and the PCM data is processed by the arithmetic unit 4 in the PCM data.
The data is transferred to the DAC circuit 6 at regular intervals depending on the frequency of the data (step S5). P transferred to the DAC circuit 6
The CM data is converted into an analog audio signal by digital-analog conversion (step S7), amplified by the amplifier circuit 7, and converted into audio by the next speaker 8. Conversely, if the average value of the PCM data is smaller than the volume level threshold, it is determined that the volume level is low (step S
5) Amplify PCM data. The amplification of the PCM data is obtained by multiplying the amplification factor for each channel by all the PCM data on the memory 5 by the arithmetic unit 4 (step S6). After that, as above, DAC
The PCM data is transferred to the circuit 6 to obtain audio. Also,
Since the value of the amplification factor at the time of first use is not determined similarly to the threshold value of the volume level, a predetermined initial value is used. The volume level threshold and the amplification factor are managed for each channel.

Here, the process of switching channels will be described with reference to FIGS. When the channel change is performed (step ST1), the existing compressed audio data and the restored PCM data are discarded, and the volume level threshold and the amplification factor are stored in the memory 5 (step ST2).
The new compressed data is taken into the memory 5 via the input control circuit 3 and the arithmetic unit 4. Subsequent processing is performed in the same manner as described above (step ST3).

Referring to FIG. 1 and FIG. 4, the processing for increasing or decreasing the volume will be described. When the volume is increased or decreased (step STP1), a volume increase / decrease signal is notified to the arithmetic unit 4 through the input control circuit 3. If the current volume is determined to be inappropriate for this channel and the volume is increased (step STP2), this is because the volume is low, so increase the amplification factor used and lower the volume volume threshold. Then, amplification is performed on a wider range of audio data (step STP3). If the volume is reduced
(Step STP2) The reverse process, that is, a process of lowering the amplification factor of the channel and increasing the threshold of the volume control is performed (Step STP4). By performing these processes, automatic volume adjustment is performed.

Next, the present invention and other embodiments will be described with reference to the drawings. Referring to FIG. 5, compared to FIG. 1, there is no channel circuit 2, and the input control circuit 3 is connected to DAT9, CD10, MD11, etc., which are sound sources.
Compressed digital data from a sound source such as DAT9, CD10, MD11 that does not need to switch channels is input to the input circuit control unit 3. After that, the data flow
As described above, the compressed data is restored to PCM data, the average value is obtained, the average value is compared with the threshold of the volume level, and if the threshold is exceeded, the PC
The M data is sent to the DAC circuit 6. If the threshold is not exceeded, the PCM data is amplified and the amplified P
The CM data is transferred to the DAC circuit 6. If there is a channel here, every time the channel switches,
The threshold and the gain of the volume level of the channel after the switching were changed to the threshold, but in FIG. 5, since there is no channel,
The volume level threshold and the amplification factor are used as they are without switching. In this embodiment, even if there is no channel circuit, if there is no need to switch sound sources, there is an effect that the optimum volume adjustment can be automatically performed only by increasing or decreasing the volume.

[0016]

The first effect is that the sound volume can be automatically adjusted without adding a special circuit. The reason is that the restoration of the compressed audio data requires an arithmetic unit and a memory, and the arithmetic operation is performed using the arithmetic unit and the memory.
The existing circuit can be used. The second effect is that the volume does not need to be changed frequently just because the volume is low or high each time a channel or program is switched. The reason is that when decompressing compressed audio data, always calculate the average value of the audio data and monitor the volume level,
Also, the amplification factor and the values necessary for the amplification are stored. The third effect is that the possibility of noise contamination due to the amplification process is small. The reason is that digital arithmetic processing is performed on the restored PCM data, so that the possibility of noise contamination is reduced as compared with the case of amplification of an analog audio signal.

[Brief description of the drawings]

FIG. 1 is a block diagram of an automatic volume control circuit according to the present invention.

FIG. 2 is a flowchart for explaining the operation of the automatic volume control circuit of the present invention.

FIG. 3 is a flowchart illustrating a channel switching process of the automatic volume control circuit of the present invention.

FIG. 4 is a flowchart for explaining processing contents when the volume is increased / decreased.

FIG. 5 is a block diagram of another embodiment of the automatic volume control circuit of the present invention.

FIG. 6 is a block diagram of an embodiment of a conventional automatic volume control circuit.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Volume 2 ... Channel circuit 3 ... Input control circuit 4 ... Calculator 5 ... Memory 6 ... DAC circuit 7 ... Amplifier circuit 8 ... Speaker 9 ... DAT 10 ... CD 11 ... MD 12 ... Tuner 13 ... CD 14 ... Reproduction tape DESCRIPTION OF SYMBOLS 15 ... Recording tape 16 ... Signal detection part 17 ... Electronic volume 18 ... Preamplifier 19 ... Power amplifier 20 ... Volume drive motor 21 ... MPU 22 ... Level detection circuit 23 ... Volume memory key 24 ... RAM

Claims (5)

[Claims] 1. A volume for generating an increase / decrease determination signal when the volume is increased / decreased, a channel circuit for generating a channel number signal selected when a program is selected, a compressed audio data signal and a volume increase / decrease determination signal. An input control circuit for controlling each input of a channel number signal;
An arithmetic unit that performs amplification processing on M data, a memory that holds information necessary for the arithmetic operation of the arithmetic unit, and that stores and holds a volume level threshold and an amplification factor, and converts the PCM data into an analog audio signal An automatic audio adjustment circuit including a DAC circuit for performing the above operation and an amplifier circuit for amplifying a signal from the DAC circuit, wherein the input control circuit inputs the compressed input audio data and records the input data to the memory via the arithmetic unit. Then, the arithmetic unit takes out the compressed audio data recorded in the memory, restores the compressed audio data to PCM data, returns the data to the memory, and records it again. The arithmetic unit adds the restored PCM data, and adds the added PCM data. Divide by the number of data to obtain an average value of the PCM data. The arithmetic unit compares the average value with a threshold of a volume level for each channel in a memory, and If the average value of the PCM data is larger than the threshold of the quantity level, the PCM
If the volume level of the data is determined to be appropriate and no arithmetic processing is performed, and if the average value of the PCM data is smaller than the threshold of the volume level, the volume level of the PCM data is determined to be low and the Amplifies the PCM data by multiplying the amplification factor for each channel by the above-mentioned arithmetic unit. Wherein the amplifier circuit has various means for amplifying an analog audio signal generated by digital-to-analog conversion by a DAC circuit. 2. A method for automatically starting the automatic audio adjustment circuit, comprising setting an initial value in advance for a threshold value and an amplification factor of a volume level required for automatically adjusting the audio volume, and starting the automatic audio adjustment. The audio automatic adjustment circuit according to claim 1, wherein 3. A volume for generating an increase / decrease determination signal when the volume is increased / decreased, a channel circuit for generating a channel number signal selected when a program is selected, a compressed audio data signal and a volume increase / decrease determination signal. An input control circuit for controlling each input of a channel number signal;
An arithmetic unit that performs amplification processing on M data, a memory that holds information necessary for the arithmetic operation of the arithmetic unit, and that stores and holds a volume level threshold and an amplification factor, and converts the PCM data into an analog audio signal An automatic audio adjustment circuit including a DAC circuit for performing a program and an amplifier circuit for amplifying a signal from the DAC circuit, wherein the channel circuit generates a channel number signal selected when a program is selected, and the input control circuit Receives the channel number signal and transfers it to the arithmetic unit. The arithmetic unit discards the compressed audio data and the restored PCM data currently recorded in the memory. The rate is stored in the memory, and the compressed data of the newly selected channel is loaded into the memory via the input control circuit and the arithmetic unit. Voice adjusting circuit and performs Rikae process. 4. A volume for generating an increase / decrease determination signal when the volume is increased / decreased, a channel circuit for generating a channel number signal selected when a program is selected, a compressed audio data signal and a volume increase / decrease determination signal. An input control circuit for controlling each input of a channel number signal;
An arithmetic unit that performs amplification processing on M data, a memory that holds information necessary for the arithmetic operation of the arithmetic unit, and that stores and holds a volume level threshold and an amplification factor, and converts the PCM data into an analog audio signal And an amplifier circuit for amplifying a signal from the DAC circuit, wherein the volume generates a volume increase / decrease determination signal according to the increase / decrease, and the input control circuit outputs a volume increase / decrease determination signal. When the volume increase / decrease determination signal is a volume increase, the arithmetic unit raises the amplification factor used for the calculation and lowers the volume volume threshold, and when the volume is decreased, Lower the amplification factor used for the calculation, raise the threshold of the volume control,
An automatic audio adjustment circuit characterized by performing volume increase / decrease processing. 5. A volume for generating an increase / decrease determination signal when the volume is increased / decreased, a channel circuit for generating a channel number signal selected when a program is selected, a compressed audio data signal and a volume increase / decrease determination signal. An input control circuit for controlling each input of a channel number signal;
An arithmetic unit that performs amplification processing on M data, a memory that holds information necessary for the arithmetic operation of the arithmetic unit, and that stores and holds a volume level threshold and an amplification factor, and converts the PCM data into an analog audio signal And an amplifier circuit for amplifying a signal from the DAC circuit, wherein compressed input audio data is input to the input control circuit and recorded in the memory via the arithmetic unit. And extracting compressed audio data recorded in the memory,
Restoring to the CM data, returning to the memory and recording again, adding the restored PCM data, and adding the added PC
Calculating the average value of the PCM data by dividing by the number of M data; comparing the average value with the threshold of the volume level for each channel in the memory; If the value is large, the volume level of the PCM data is determined to be appropriate and no arithmetic processing is performed, and if the average value of the PCM data is smaller than the volume level threshold, the volume level of the PCM data is A process of amplifying PCM data by multiplying an amplification factor for each channel in the memory by determining that the PCM data is small,
D at regular intervals determined by the frequency of M data
A method for automatically adjusting audio, comprising: transferring to an AC circuit; and amplifying an analog audio signal generated by the amplifier circuit being digital-to-analog converted by a DAC circuit.