JP2008041174A - Data reproducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain a user-friendly data reproducing device causing no distortion in reproduced sound, with noise suppressed as much as possible to acquire faithful reproduction when reproducing digital voice data amplified at different amplification degrees besed on one voice and recorded on a recording medium 10. <P>SOLUTION: When two digital signals acquired by amplifying an analog signal from a microphone 2 by amplifiers 20, 21 with different amplification degrees and are further recorded in a recording medium, DSP 3 selects one digital data having a larger amplification degree among them, and when the selected digital data has a part exceeding a reproducible level, the DSP 3 reproduces the digital data of the reproducible level corresponding to the other digital data instead. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

In the present invention, incoming speech such as an interview or music performance is converted into an electrical signal by a microphone, and the electrical signal related to the speech is amplified to an appropriate level and then recorded as digital audio data on a recording medium. In this case, the present invention relates to a data reproducing apparatus for reproducing audio data recorded on the recording medium.
When the data recording device records audio data on a recording medium, if the level related to the input of sound to the microphone exceeds the maximum input level of the data recording device, the audio exceeding the maximum input level is distorted during playback. It appears.
In particular, the present invention relates to an improvement in reproduction of audio data that can avoid distortion during reproduction.

First, recording of audio data, which is a premise for reproducing audio data, will be described.
A data recording apparatus converts an audio signal input from a microphone into an electric signal, an amplifier amplifies the electric signal to an appropriate level, and further, an A / D converter converts the electric signal amplified to the appropriate level. Is converted into digital audio data, and the DSP functions to record the audio data on a recording medium such as a semiconductor memory.
When the data recording device records audio data, the microphone converts the electrical signal converted from the audio so that a desired level of reproduced audio can be obtained when the audio data is recorded at a good level and reproduced as a result. Amplification to an appropriate level is always performed.

Amplification of an appropriate level of the electric signal is preferably as large as possible in order to reliably record audio data to be recorded and to suppress noise.
However, if the amplification level is increased too much, the maximum input level (hereinafter referred to as “VMAX”) of the audio data recording apparatus will be exceeded. In such a case, since it is impossible for the A / D converter connected to the rear stage side of the microphone to take a value higher than VMAX, it is assumed that all electric signals whose input level exceeds VMAX have a value of VMAX. It will be considered and converted to a digital signal at the level of its maximum input.

It should be noted that the level of data exceeding the VMAX is recorded on the recording medium and is not recorded faithfully to the sound at the time of pickup when it is subsequently played back. Will not be played back faithfully.
Therefore, VMAX is a limit value of a level that can be reproduced in the reproduction output.

Here, the electrical signal related to the sound whose input level exceeds VMAX is simply recorded as digital sound data of the maximum input level.
Therefore, when the sound data is restored to analog sound, the sound at the portion where the input level exceeds VMAX is reproduced as distorted sound, which corresponds to the sound actually picked up by the microphone. It is not played back as audio.
That is, faithful recording and reproduction of audio data cannot be obtained.

When recording audio data, the level of audio input is too high, and as a result, there is a problem that distortion occurs in the reproduced audio. In order to avoid such a problem, several methods have been tried in the past.
As one of the countermeasures against the occurrence of distortion, there is known a method of reducing the recording level by lowering the recording volume with respect to the electric signal related to the sound inputted after the microphone.

However, in this method, the recording volume is excessively lowered to make sure that the input level does not exceed VMAX, the recording volume becomes too low, and the level becomes too small. A new problem arises that the noise around the sound source is greatly recorded.
Secondly, there is a method in which an AGC circuit (automatic gain control circuit) is provided after the microphone to control the level of the input electric signal related to the sound. In such a method, since the input level is controlled, the level of the input signal does not exceed VMAX.

However, in the configuration in which the AGC circuit is arranged after the microphone, for example, when the voice input is lost or the input voice level suddenly becomes extremely low during the interview, that is, during the recording of the voice data. The AGC circuit works so that the gain automatically increases when the input level decreases, and this action amplifies even the noise around the target sound source, resulting in a noisy recording. The problem of becoming.
When the sound picked up by the microphone is recorded as sound data and the sound data is reproduced at a desired time, it is desirable that the sound obtained by the reproduction is approximate if it is close to the sound picked up by the microphone. In other words, the fidelity of audio data recording and the fidelity of audio data reproduction have great significance, and naturally reproduced audio with enhanced noise is not desirable.

Here, in order for the reproduced sound to be faithful to the sound picked up by the microphone, first, it is important that the level of the input signal is equal to or lower than VMAX of the data recording apparatus and the sound data is recorded.
On the other hand, when audio data whose input level exceeds the VMAX of the data recording apparatus is reproduced, there arises a problem that faithful reproduction cannot be obtained due to distortion. In order to solve this problem, the following documents are known as inventions for avoiding distortion in reproduced sound without suppressing the input level.

JP 2000-261263 A

Japanese Patent Laid-Open No. 2000-261263 discloses a volume margin that can be raised based on a maximum value and a reference value of a volume that is output, and holds the detected value, thereby producing a volume corresponding to the detected margin. A volume controller (hereinafter referred to as “prior invention”) that enables adjustment is disclosed.
With the volume controller having such a configuration, even if the volume is increased too much, the range is not over by the detected and held volume margin, and as a result, no distortion occurs on the output side.

That is, when audio data is obtained and recorded by the prior invention having such a configuration, reproduced audio without distortion can be obtained.
However, since the prior invention has a configuration in which the volume margin that can be increased is determined, it is not possible to cope with the range over for the input of the volume exceeding the volume margin, so that faithful audio data recording can be obtained. As a result, there is a problem in that sound corresponding to the original sound cannot be obtained during reproduction.

In particular, the problem becomes more serious as the volume margin value is smaller and the original sound greatly exceeds the volume margin.
Therefore, when amplifying the electric signal related to the sound from the microphone, the electric signal is amplified with a plurality of different amplification degrees, and the electric signal having the higher amplification degree among the electric signals obtained by the amplification is amplified. In order to reproduce the audio data related to the signal and to reproduce the audio data related to the electric signal not exceeding VMAX when the electric signal having the higher amplification exceeds VMAX, By properly using the signals, it is possible to reproduce sound with high fidelity without distortion.

However, it is technically very difficult for the user to properly use the above-mentioned audio data, which is a troublesome work and causes a problem of lack of practicality.
The present invention has been made in view of the above circumstances, and an electric signal related to the same sound is amplified in a plurality of ranges, that is, a plurality of amplification degrees, and further, a plurality of digital signals recorded on a recording medium. When the audio data is reproduced, a data reproducing apparatus is provided in which the reproduced sound is not distorted, noise is suppressed as much as possible, reproduction fidelity is obtained, and handling is simple.

  In the present invention, a plurality of electrical signals obtained by amplifying analog signals of the same input with different amplification degrees are recorded as digital data on a recording medium, and the digital data is read from the recorded recording medium and reproduced. In this case, select the one with the larger amplification level from the multiple digital data, and if the selected digital data has a part that exceeds the reproducible level, it can be played back with other digital data. This is a data reproduction apparatus configured to reproduce by replacing with a digital data portion of a certain level.

The detailed configuration is that a plurality of amplified analog signals having different amplification levels are generated from a single analog signal using a plurality of amplification levels prepared in advance, and each of the plurality of amplified analog signals is digitally generated. In a data reproducing apparatus for reproducing the digital data from a recording medium that is converted into data and recorded in association with the plurality of digital data,
Among a plurality of digital data read from the recording medium, data whose reproduction output level exceeds a preset limit value from the digital data corresponding to the amplified analog signal in which the maximum amplification degree is set And the reproduction output level of the detected data is less than or equal to the limit value from the digital data corresponding to the amplified analog signal in which another amplification degree lower than the maximum amplification degree is set. A data reproducing apparatus comprising: reproducing means for extracting substitute data and replacing the detected data with the substitute data for reproduction.

Here, the digital data not exceeding the reproducible level means data obtained by recording data not exceeding the recordable level when recording analog data.
A specific example of the means for performing the detection, the extraction, and the replacement is a digital signal processor.

  In addition, the data reproducing apparatus has a function of making the amplification levels of the two data common before replacing the detected data with the substitute data.

  The present invention selects digital data that does not exceed a reproducible level from among the plurality of digital data when the digital data that has been amplified with a plurality of amplification degrees and associated with each other is read out from the recording medium and reproduced. Since it is played back, distorted digital data due to exceeding the playable level is not played back, and noise can be kept low because it uses data with less noise within the playable level range. Therefore, the data reproduction apparatus has high reproduction fidelity and is easy to handle.

The present invention will be described in detail below based on the best mode shown in the drawings. However, the present invention is not limited by this form.
As shown in FIG. 1, the data reproducing apparatus 1 includes a buffer memory 2, a digital signal processor 3 (hereinafter referred to as “DSP 3”), a control unit 4, a D / A converter 5, an amplifier 6, and the like. A speaker 7, an operation unit 8 and a display unit 9 are provided.

A bus 11 is provided between the recording medium 10 and the buffer memory 2, a bus 12 is provided between the buffer memory 2 and the DSP 3, a bus 13 is provided between the control means 4 and the DSP 3, and the DSP 3 and the D / A converter 5 are connected. Buses 14 are respectively interposed between them.
Further, the control means 4 includes an input unit 15, a calculation unit 16, a memory 17 and an output unit 18.

The data reproducing apparatus 1 has a sound data recording function for converting picked-up sound into sound data and recording the sound data.
That is, the data reproducing apparatus 1 includes a microphone 19, amplifiers 20 and 21, electronic volumes 22 and 23 (hereinafter referred to as “EVR22 and 23”), and A / D converters 24 and 25. .

In the data reproducing apparatus 1, the buffer memory 2, the DSP 3, the control means 4, the operation unit 8 and the display unit 9 are shared between the audio data recording function and the audio data reproducing function. It is configured.
Here, the present invention relates to the reproduction of audio data. Since it is premised that the audio data to be reproduced exists in advance, the audio data recording function will be described first.

The microphone 19 converts a voice of a person, a sound of nature, a music of a concert, etc. into an analog electric signal and outputs it to the subsequent stage.
Both the amplifiers 20 and 21 are connected to the subsequent stage of the microphone 19, receive the electrical signal related to the sound from the microphone 19, amplify each by 300 times, and send the amplified electrical signal to the EVRs 22 and 23 of the subsequent stage.

When the EVRs 22 and 23 receive a control signal from the control means 4 at the time of recording standby or recording function, the EVR 22 changes the attenuation amount to 1/4 and the EVR 23 changes the attenuation amount to 1/12. In addition, each of the amplifiers 20 and 21 functions so that the gain of the electric signal related to the sound from the microphone 19 is 75 times and 25 times the desired value.
The A / D converters 24 and 25 are connected to the subsequent stages of the EVRs 22 and 23, respectively. When analog electric signals processed to a desired level are input, they are converted into digital electric signals and sent to the bus 14. Output.

Here, the analog electrical signal related to the sound from the microphone 19 is amplified by the amplifier 20, a desired gain is secured by the EVR 22, converted into a digital electrical signal by the A / D converter 24, and input to the bus 14. Amplified by the first main system and the amplifier 21, a desired gain is secured by the EVR 23, converted into a digital electric signal by the A / D converter 25, and supplemented to be input to the bus 14. This is the source of the second system.
The bus 14 receives two digital electric signals having different amplification levels from the A / D converters 24 and 25, and sends the two electric signals to the DSP 3 in association with each other.

When the DSP 3 receives two digital electrical signals related to the mutually associated sounds from the A / D converters 24 and 25 via the bus 14 based on the control signal from the control means 4, the electrical signal Is sent to the buffer memory 2 for recording in the recording medium 10 as audio data. That is, here, the DSP 3 functions as a recording means.
Similarly, the DSP 3 reads the digital audio data recorded on the recording medium 10 via the buffer memory 2 based on the control signal from the control means 4 and sends it to the D / A converter 5 to send the audio data. It functions to reproduce analog electrical signals related to audio. That is, the DSP 3 also functions as a reproducing unit.

  The control means 4 includes an input unit 15 that receives control signals and data signals such as recording start / stop and playback start / stop from the operation unit 8, a non-volatile memory 17 that stores the amplification degree of the microphone amplifier, and the like. A calculation unit 16 that generates a control signal by performing determination and calculation corresponding to the contents of the operation signal from the input unit 15, and outputs the control signal generated by the calculation unit 16 to the EVRs 22 and 23, the DSP 3, and the display unit 9. An output unit 18 is provided.

The amplification degree of the microphone amplifier stored in the memory 17 can be changed by an operation from the operation unit 8.
Specifically, when recording the audio data, the arithmetic unit 16 receives the recording start input from the operation input, reads the amplification degree from the memory 17, and sets the EVRs 22 and 23 so as to obtain a desired amplification degree. The value is calculated and output to the EVRs 22 and 23.

The buffer memory 2 is substantially interposed between the DSP 3 and the recording medium 10 and temporarily stores digital electric signals from the DSP 3 via the bus 11.
The buffer memory 2 provides a buffering function for the flow of audio data to the recording medium 10 while temporarily holding the audio data from the DSP 3.

The display unit 9 displays the current state of the function of the apparatus, the operation content, confirmation items, and the like based on the control signal from the control means 4.
Specific examples of the recording medium 10 include a semiconductor memory. In addition, CD, MD, etc. may be sufficient.

Hereinafter, means for reproducing the audio data of the data reproducing apparatus 1 will be described.
The means for reproducing the audio data of the data reproducing apparatus 1 basically amplifies the audio data related to the higher one of the audio data related to the two systems recorded in association with each other on the recording medium 10. Means for preferentially selecting and reproducing the audio data relating to the first system obtained by amplification at a degree, and recording on the recording medium 10 which is an electrical signal relating to the audio data relating to the first system When an audio having an input level exceeding VMAX is recorded, an electric signal related to the audio data related to the second system recorded in association with the audio is selected and output.

Specifically, when the buffer memory 2 receives the control signal from the control means 4 via the DSP 3, the buffer memory 2 reads out the audio data recorded on the recording medium 10 via the bus 11 and temporarily holds it. A buffer function is provided for the flow of audio data to the DSP 3.
First of all, the DSP 3 reads out the audio data related to the first system having the higher input level at the time of recording the audio data from the buffer memory 2 via the bus 12 based on the control of the control means 4. It is detected whether or not the peak of the input level has exceeded the VMAX level at the time of recording.

  Here, when the audio data related to the first system amplified by the higher amplification degree of the DSP 3 is read from the recording medium 10, the recording of the first electric signal corresponding to the audio data related to the first system is performed. When the DSP 3 determines that the peak of the level at the time of input does not exceed the VMAX of the device that records the audio data and is input at a level lower than the VMAX and is consequently recorded as the audio data, the DSP 3 uses the bus The first electric signal is not sent to the D / A converter 5 via 14 and the second electric signal corresponding to the audio data related to the second system is not sent.

  On the other hand, when the DSP 3 reads the audio data related to the first system from the recording medium 10, the peak of the level at the time of recording input of the first electric signal corresponding to the audio data related to the first system is the audio data. If the DSP 3 determines that there is a portion exceeding the VMAX of the recording device, the DSP 3 transmits the first system audio data and the second system audio associated with each other via the bus 12. When the data is read and the audio data portion where the peak level does not reach VMAX when the audio data is recorded, the first system audio data is sent to the bus 14, and the electric signal portion where the peak level reaches VMAX is the first. It is configured to function to switch to the second system of audio data and send it to the bus 14.

Therefore, if the peak of the electrical signal when recording audio data does not reach VMAX, it is determined that the recorded audio data does not have a portion due to excessive input, and the audio data related to the first system is The first electric signal is sent to the D / A converter 5 via the bus 14, converted from a digital signal to an analog signal, amplified to a desired level by the amplifier 6, and then converted into sound from the speaker 7. Will be output.
On the other hand, if it is determined that there is a part where the peak of the electrical signal when recording the voice data reaches VMAX and it has an excessive input part, the DSP first relates to the voice data related to the first system. The selection is sequentially switched from the electric signal of the second to the second electric signal related to the audio data related to the second system whose amplification is lower by 10 dB, and only the electric signal of the audio related to the selected one is D / A. It will be sent to the converter 5.

Further, when the input level of the first electric signal related to the audio data related to the first system is VMAX and the input level is continuously equal, the electric signal of that portion is regarded as an excessive input portion, The second electrical signal related to the audio data related to the second system is selected and adopted.
If the electrical signals are switched by connecting the electrical signals while maintaining the amplification levels of the first system and the second system as they are, the recording level will be different and inconvenience will occur. The electric signal is switched so as not to cause a level difference between the electric signal and the second electric signal related to the audio data related to the second system.

That is, the level difference between the first electrical signal related to the first system and the second electrical signal related to the second system is accurately detected by a level difference detection unit (not shown), and then the level difference The level of the first electric signal related to the first system is shifted down by the value (about 10 dB).
This shift down is calculated by multiplying the value of the level difference between the first electrical signal related to the first system and the second electrical signal related to the second system by the value to be shifted (about 10 dB). That is, when the first electrical signal related to the first system is leveled down to about one third of the original value, it becomes the same level as the second electrical signal related to the second system.

When the electric signal related to the first system and the audio data related to the second system are selectively reproduced and output during reproduction, the data reproducing apparatus 1 determines the level of the electric signals of the two systems in the DSP 3. After being aligned, the audio signal is recorded so that the electric signals related to the first and second audio signals are selected for the electric signal portion over the VMAX when recording the audio data.
That is, among the audio data reproduced from the recording medium 10, data in which the reproduction output level exceeds the preset limit value for the first system audio data is detected.

The DSP 3 extracts the second system audio data corresponding to the portion corresponding to VMAX at the time of recording the audio data as the limit value in which the reproduction output level is set in advance, that is, the audio data of the first system.
Here, since the first system and the second system have different amplification levels at the time of the first amplification, the control means 4 having received the extraction of the substitute data controls the DSP 3 to share the amplification levels. Output a signal.

Accordingly, the DSP 3 lowers the level of the first audio data so as to share the amplification degree, and then replaces the audio data of the second system as substitute data for the portion detected as exceeding VMAX.
At this time, the control means 4 outputs to the DSP 3 a control signal indicating what should be selected as audio data for reproduction based on the fact that the first audio data has exceeded VMAX during recording.

On the other hand, the level is lowered in order to make the electric signal levels of the two systems uniform, and as a result, there is a possibility that a problem that the level becomes too low may occur.
In the data reproducing apparatus 1, in response to the possibility of such a problem that the level becomes too low, the DSP 3 selects and generates the electrical signal related to the first system and the electrical signal related to the second system. The level is increased by shifting the level by a difference (margin) between the peak value of the electrical signal related to the voice and the VMAX, and this level shift is performed.

With such a configuration, the peak value of the second electric signal according to the second system is a level that can be amplified without damaging the audio data to be recorded up to the maximum VMAX value.
Therefore, the audio data recording apparatus 1 has such a configuration that the output of the electric signal related to the sound is increased by the amount that the level has been raised rather than the original low level, and the electric signal-to-noise related to the sound is increased in the apparatus. The ratio is advantageous.

Therefore, the first electric signal related to the first system in which the sound is distorted due to the excessive input even if it is advantageous corresponding to the electric signal related to the low level sound, and the excessive input is compatible with the noise. From the second electric signal related to the second system in question, an audio electric signal corresponding to noise suppression and corresponding to an excessive input, which closely approximates the audio picked up by the microphone 19, passes through the bus 12. And output from the DSP 3 to the D / A converter 23.
The selection switching between the first electrical signal related to the first system of the DSP 3 and the second electrical signal related to the second system is performed after the recording of the file related to the audio data is completed. Separately from the above, when recording, the value with the highest recording level, that is, the peak value of the recording period is recorded on the recording medium 10 as an attached file of the audio data file, and the audio data is reproduced when the audio data is reproduced. The configuration may be such that it is performed based on the peak value recorded in the attached file.

In other words, when creating audio data, a procedure for selecting and switching electrical signals is applied in advance.
The D / A converter 5 receives either the digital audio electrical signal of the audio data related to the selected first system or the digital audio electrical signal of the audio data related to the second system from the DSP 3 via the bus 14. In response, the signal is converted into an analog signal and sent to the amplifier 6.

The amplifier 6 amplifies the electric signal related to the analog sound from the D / A converter 5 to a desired level and then sends it to the speaker 7.
The speaker 7 converts an electrical signal related to the sound from the amplifier into sound and outputs the sound.
In such a configuration, the DSP 3 reads the audio data from the recording medium 10 and whether the level of the electric signal related to the audio exceeds VMAX or not. Where is the part of the electrical signal that exceeds VMAX? Therefore, it is configured not to require the work of detecting.

The data reproducing apparatus 1 is configured as described above. Hereinafter, the use of the data reproducing apparatus 1 will be described.
The user sets the recording medium 10 in the data reproducing apparatus 1 and then turns the main power source by operating the operation unit 8 toward the sound source (not shown) in which the microphone 19 is to be recorded.

Subsequently, after operating the operation unit 8 to set the recording level and the like, recording, that is, recording of audio data is started.
Here, the microphone 19 picks up the sound from the sound source and converts the sound into an analog electric signal, and the electric signal forms an amplifier 20 constituting the first system and an amplifier 21 constituting the second system. Send to.

When receiving the electrical signal from the microphone, the amplifiers 20 and 21 amplify each of them by 300 times, and send the amplified electrical signals to the EVRs 22 and 23.
The EVR 22 changes the attenuation amount of the amplified electric signal from the amplifier 20 to ¼ based on the control signal from the control unit 4, and as a result, the electric signal related to the sound from the microphone 19. The gain is sent to the A / D converter 24.

On the other hand, the EVR 23 changes the attenuation amount with respect to the amplified electric signal from the amplifier 21 based on the control signal from the control means 4 so that the level becomes 1/12. As a result, the sound from the microphone 19 is changed. It functions so that the gain of the electrical signal according to the above becomes 25 times the desired value and sends it to the A / D converter 25.
At this time, the characteristic curves of the electric signals of the first system and the second system are respectively displayed as a diagram shown in the upper part of FIG. 3 and a diagram shown in the middle part.

When the A / D converters 24 and 25 receive electrical signals related to analog audio from the EVRs 22 and 23, respectively, they are converted into digital electrical signals and output to the bus 14.
The bus 14 sends two digital audio data having different levels from the A / D converters 24 and 25 to the DSP 3.

When the DSP 3 receives two digital audio data of different levels from the bus 14 based on a control signal from the control means 4, the DSP 3 associates the two audio data with each other via the bus 12 and buffers the buffer memory 2. Send to.
When the buffer memory 2 receives two digital audio data having different levels associated with each other from the DSP 3 via the bus 12, the buffer memory 2 temporarily stores the audio data and performs a buffer function as a bus as audio data. 11 to the recording medium 10.

Here, the recording medium 10 is a state in which audio data related to the first system and the second system, which are two gains of 75 times and 25 times the sound from the microphone 19, are recorded in association with each other. become.
When the user reproduces the audio data relating to these two systems recorded on the recording medium 10 using the data reproducing apparatus 1, the data reproducing apparatus 1 operates as follows.

The user operates the operation unit 8 to display a reproduction target list on the display unit 9 and specifies audio data to be reproduced.
Here, when the user operates the operation unit 8 to perform the operation so as to reproduce the specified audio data, a command signal for reproducing the audio data is sent from the operation unit 8 to the input unit 15 of the control unit 4. .

Based on the command signal from the input unit 15, the calculation unit 16 of the control unit 4 reads data necessary for processing audio data during reproduction from the memory 17, and the operation of the apparatus shifts to the reproduction function. It is determined whether or not it is ready, and a command signal for reproducing the audio data is sent from the output unit 18 to the DSP 3.
When the DSP 3 receives the audio data reproduction command signal from the control unit 4, the DSP 3 sends a control signal for reading audio data to be reproduced from the recording medium 10 to the buffer memory 2.

The buffer memory 2 reads and temporarily stores the audio data related to the two digital audio data having different levels associated with each other and recorded on the recording medium 10 via the bus 11, and the audio data A buffer function is performed on the audio data flow and is sent to the DSP 3.
Here, the DSP 3 functions as shown in FIG. That is, the DSP 3 first reads out the first audio data related to the first system having the higher amplification level and the higher input level at the time of recording the audio data from the buffer memory 2, and the audio data It is detected whether or not the peak of the input level has exceeded the VMAX level at the time of recording.

  Here, the DSP 3 detects the peak of the level, and the first system amplified by the higher amplification degree, that is, the analog electric signal from the microphone 19 is amplified 300 times by the amplifier 20 and 1 by the EVR 22. When the audio data related to the system attenuated to / 4 is read from the recording medium 10, the peak of the level at the time of recording input of the first electric signal related to the first system is VMAX of the apparatus that records the audio data. If it is determined that the reproduction output level has not exceeded the preset limit value, the DSP 3 reproduces from the audio data related to the first system via the bus 14 and outputs the first electric signal to the D / D. The analog electric signal from the second system, that is, the microphone 19 is amplified 300 times by the amplifier 21 and attenuated to 1/12 by the EVR 23. It does not send a second electrical signal according to the system.

On the other hand, the DSP 3 reads the audio data related to the first system from the recording medium 10, and the peak of the level at the time of recording input of the first electric signal corresponding to the audio data related to the first system records the audio data. When there is a part exceeding the VMAX of the device to be operated, that is, when it is detected that there is a part where the reproduction output level exceeds a preset limit value, the DSP 3 detects the first system associated with each other. The first audio data according to the second system and the second audio data according to the second system are read out, and the audio data portion where the peak level at the time of recording the audio data does not reach VMAX is the first related to the first system. As for the voice data, the second voice data related to the second system is extracted from the voice data portion where the peak level reaches VMAX.
Subsequently, the DSP 3 has a common range between the first audio data and the second audio data because the amplification level differs between the first system and the second system due to amplification during recording of the audio data. After the conversion, the portion of the first audio data that exceeds VMAX is replaced with the corresponding portion of the second audio data.
Therefore, as a result, audio data indicated by “reproduction output” in FIG. 3 is output.

The common use of the range means that the amplification degree differs between the first system and the second system when the amplifiers 20 and 21 amplify the electrical signals related to the sound, and the amplification degree is the same. Furthermore, it means that the level is adjusted between the first audio data and the second audio data.
The standardization of the range of the first audio data and the second audio data is performed by first detecting the level difference between the two audio data accurately by the built-in level difference detection unit (not shown) in the DSP 3. This is done by shifting down the level of the audio data of the first system by the level difference value (about 10 dB).

Here, the audio data of the first system is leveled down to about one third of the original value, and becomes the same level as the audio data of the second system.
In this example, the common range is used before connecting (replacement) the audio data of the first system and the audio data of the second system, but the audio data of the second system is replaced with the substitute data. Alternatively, the range may be shared (level adjustment) after replacement with a portion exceeding VMAX of the first system.

The DSP 3 sends the joined audio data obtained here as reproduction audio data to the D / A converter 5 via the bus 14.
At this time, the D / A converter 5 inputs audio data having a level lower than that of VMAX, is returned from the digital signal to an analog signal, and subsequently amplified to a desired level by the amplifier 6. It is output after becoming a voice.

When the DSP 3 detects that the input level of the first system audio data is VMAX and the input level is continuously equal, the DSP 3 detects the portion of the audio data whose input level is continuously equal to the excessive input portion. In other words, the second audio data related to the second system is selectively switched and adopted on the assumption that the reproduction output level has reached the limit value.
That is, when the electric signal of the first system is amplified and data is recorded, the input level may actually continue to be just VMAX or may exceed VMAX. Therefore, since the same data is recorded on the recording medium 10 and it is difficult to discriminate it, the audio data according to the second system is adopted to obtain the fidelity of the original audio.

In order to make the range common, the audio data of the first system is shifted down, and the second audio data of the alternative data is connected to the audio data that has been down-leveled in the first system. When the peak of the reproduced audio data is sufficiently lower than the limit value of the reproduction output level (value corresponding to VMAX) and the difference (margin) between the peak and the value corresponding to VMAX is sufficiently large, It is also possible to perform processing to increase the level of audio data within the range of the limit value of the reproduction output level.
By processing the DSP 3 for such a level, it becomes possible to cope with a case where the level becomes too low due to the common use of the range.

As described above, the data reproducing apparatus 1 reproduces the audio data related to the first system that can suppress noise, and the audio data related to the first system is excessively input during recording and is distorted when reproduced. In the portion that is output as audio, audio without distortion is output by the audio data related to the second system, so that it is possible to reproduce audio with low noise and no distortion.
Further, the data reproducing apparatus 1 does not require a complicated operation.

In the data reproducing apparatus 1, as described above, the DSP 3 reads the audio data related to the first system from the recording medium 10, and detects whether or not the peak exceeds the limit value of the reproduction output level.
On the other hand, when creating audio data in advance, record the highest recording level among the recordings separately from the audio data file, that is, the peak value of each recording period as a file attached to the audio data file on the recording medium. When reproducing audio data, there is a peak at which the reproduction output level exceeds the limit value based on whether or not the DSP has read the attached file recorded on the recording medium and reached the maximum input. It may be configured to detect whether or not.

The data reproducing apparatus 1 is configured to handle two systems of audio data, that is, audio data of two different amplification ranges, but may be configured to handle audio data of three or more different amplification ranges.
Further, the data reproducing apparatus 1 has an amplification level difference between the two systems of 10 dB, and lowers the first system audio data by 10 dB, thereby sharing the level with the second system audio data. However, it is preferable to perform level sharing by reducing the level corresponding to the difference in amplification level.

FIG. 2 is a block diagram illustrating a configuration when a recording medium is connected to an optimum embodiment of the present invention. It is a structure explanatory drawing explaining the signal processing function of DSP of the form shown in FIG. In the embodiment shown in FIG. 1, the relationship between two signals when amplified with different amplification degrees and a signal obtained by connecting the two signals at a maximum input voltage or less using the embodiment shown in FIG. FIG.

Explanation of symbols

1: Audio data recording device 2: Buffer memory 3: Digital signal processor (DSP)
4: Control means 5: D / A converters 6, 20, 21: Amplifier 7: Speaker 10: Recording medium 19: Microphones 24, 25: A / D converter

Claims (3)

From one analog signal, a plurality of amplified analog signals each having a different amplification degree are generated using a plurality of amplification degrees prepared in advance, and the plurality of amplified analog signals are converted into digital data, respectively. In a data reproducing apparatus for reproducing the digital data from a recording medium on which a plurality of digital data are recorded in association with each other,
Among a plurality of digital data read from the recording medium, data whose reproduction output level exceeds a preset limit value from the digital data corresponding to the amplified analog signal in which the maximum amplification degree is set Detect
With respect to the detected data, substitute data whose reproduction output level is equal to or lower than the limit value is extracted from the digital data corresponding to the amplified analog signal in which another amplification degree lower than the maximum amplification degree is set. And
A data reproduction apparatus comprising reproduction means for reproducing the detected data by substituting the substitute data. The data reproducing apparatus according to claim 1, wherein a DSP is provided as means for reproducing digital data, and the DSP performs the detection, the extraction, and the replacement. 3. The data reproducing apparatus according to claim 1, wherein the data reproduction device is configured to share the amplification degree of the detected data before replacing the detected data with the substitute data.

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