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JP2005136635

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DESCRIPTION JP2005136635
PROBLEM TO BE SOLVED: To easily perform adjustment of reproduction sound quality when
performing audio reproduction with a simple configuration. SOLUTION: A frequency
characteristic of audio data obtained by input or reproduction is analyzed, and from the analyzed
frequency characteristic, an equalizer processing is performed to increase a gain for a frequency
band which is included in many audio data, and the equalizer processing is performed. It was
made to output processed audio data. In addition, when the equalizer processing state based on
the analysis result of the frequency characteristic is stored and the audio data is newly analyzed,
the average of the newly analyzed result and the stored equalizer processing state Then, a new
equalizer processing state is set, and the stored data is updated in the new equalizer processing
state. [Selected figure] Figure 2
Audio data processing method and apparatus
[0001]
The present invention relates to an audio data processing method and apparatus suitable for
application to an audio device that outputs audio data reproduced from, for example, various
media.
[0002]
Conventionally, when reproducing audio data recorded on a recording medium (storage medium)
such as CD (Compact Disc) or MD (Mini Disc) by an audio device, the user performs various
adjustment operations provided for the device. You can operate the unit and play it with your
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favorite sound quality.
For example, according to the sound quality of the audio to be reproduced, it is possible to make
an adjustment that enhances or weakens the high range or the low range.
[0003]
If a function called a graphic equalizer is built in, it is possible to emphasize or weaken each band
divided finely. Furthermore, when a function called a parametric equalizer is built in, it is possible
to freely change the adjustable band.
[0004]
In such conventional sound quality adjustment processing, while the user actually listens to the
music and the like reproduced at that time, the user operates the knobs for adjustment and the
like to adjust so as to obtain the desired sound quality. There is a problem that it takes time and
effort because the adjustment is performed manually while listening to the sound. In addition,
audio sources to be reproduced include various genres such as classical music, rock, jazz and pop
music, and even in the same genre, characteristics such as frequency components are diverse for
each song. Therefore, even if the audio source named source A is properly adjusted, if another
audio source named source B is played back, the sound quality will be very unnatural as it is.
[0005]
As a method for solving this problem, for example, Patent Document 1 discloses that a sound
output from a speaker is picked up by a microphone, frequency characteristics are measured
from the picked up sound, and sound field correction is performed. There is. Japanese Patent
Application Laid-Open No. 5-184000
[0006]
However, as described in Patent Document 1, in the processing of picking up a sound to be
reproduced using a microphone and measuring the frequency characteristic of the sound, an
audio processing which is completely different from a system for reproducing an audio signal
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There is a problem that the system is required and the device configuration becomes very
complicated.
[0007]
The present invention has been made in view of the foregoing, and it is an object of the present
invention to make it possible to favorably adjust the reproduction sound quality when
performing audio reproduction with a simple configuration.
[0008]
The present invention analyzes the frequency characteristics of audio data obtained by input or
reproduction, performs equalizer processing to increase the gain for a frequency band that is
included in many audio data from the analyzed frequency characteristics, and performs the
equalizer processing. It is designed to output processed audio data.
[0009]
By doing this, since the frequency characteristic is analyzed from the audio data itself to be
processed for output, it is possible to adjust the frequency characteristic according to the output
characteristic of the audio that is actually output.
[0010]
According to the present invention, the frequency characteristic is analyzed from the audio data
itself to be processed for output, so adjustment of the frequency characteristic according to the
output characteristic of the audio actually output becomes possible, and it is automatically
optimum. While adjustment can be performed, analysis and adjustment of frequency
characteristics can be performed in the circuit for output processing, and processing can be
performed with a simple configuration as compared with the case where the reproduced sound is
picked up and analyzed by a microphone or the like.
[0011]
In this case, it is possible to perform better adjustment by performing the equalizer processing
for reducing the gain in the frequency band where the component included in the audio data is
small from the analyzed frequency characteristics.
[0012]
In addition, the frequency band in which the equalizer processing is performed is variably set
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based on the analyzed frequency characteristic, and the frequency width for changing the gain is
variably set based on the analysis result, so as to match the audio data to be reproduced more.
Good adjustments are possible.
[0013]
Also, when the equalizer processing state based on the analysis result of the frequency
characteristic is stored and analysis of audio data is newly performed, the average of the newly
analyzed result and the stored equalizer processing state Then, by setting a new equalizer
processing state and updating the stored data in the new equalizer processing state, the user is
gradually and properly adjusted according to the tendency of the audio reproduced. Become.
[0014]
Hereinafter, an embodiment of the present invention will be described with reference to the
attached drawings.
FIG. 1 is a block diagram showing an example of the overall configuration of an audio
reproduction apparatus according to an embodiment of the present invention.
The audio reproducing apparatus of this embodiment includes, as an audio signal source, a CD
reproducing unit 11 for reproducing a CD, which is an optical disc on which audio data is
recorded, and an MD for reproducing an MD, which is an optical disc or a magnetooptical disc on
which audio data is recorded. It comprises a reproduction unit 12, a memory card reader 13 for
reading stored data of a memory card storing audio data, and an analog reproduction unit 14 for
reproducing an analog disk or a tape cassette.
The analog audio signal reproduced by the analog reproduction unit 14 is digitized by an analog
/ digital converter 15.
In addition, when audio data or the like read out from the memory card is compressed and
encoded, decoding processing is also performed.
[0015]
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The audio data obtained by reproduction by the respective reproduction units 11 and 12 and the
card reader 13 and the audio data converted by the analog / digital converter 15 are supplied to
the input switching unit 16 to select a desired input audio. Perform input processing.
The audio data selected by the input switching unit 16 is supplied to a DSP (Digital Signal
Processor) unit 20.
The DSP unit 20 is a circuit that processes audio data by digital data processing, and is an
integrated circuit.
A memory 30 is connected to the DSP unit 20, and data obtained based on processing is stored.
Details of the DSP unit 20 and processing using the memory 30 will be described later.
[0016]
The audio data processed by the DSP unit 20 is supplied to the digital / analog converter 17 to
be an analog audio signal, and the converted analog audio signal is supplied to the amplifiers 18L
and 18R of the two left and right channels, and the speaker is The amplified audio signal is
supplied to the left and right speakers 19L and 19R and output.
[0017]
FIG. 2 is a block diagram showing a portion related to the processing in this example in the DSP
unit 20. As shown in FIG.
The input audio data is subjected to filtering such as noise removal by the filter 21, and the filter
output is supplied to the FFT unit 22. The FFT unit 22 performs high speed Fourier transform
processing to divide into audio components for each of a plurality of frequency bands, and
supplies the divided audio data to the equalizer unit 23.
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[0018]
In the equalizer unit 23, based on the control from the control data generation unit 25,
processing for increasing the gain for each band or processing for decreasing the gain is
performed as necessary, and the data of each band subjected to the processing is Synthesize. As a
process of performing this combination, for example, an IFFT unit (inverse fast Fourier transform
unit) that performs an inverse operation to the FFT unit 22 may be provided.
[0019]
Then, in this example, the audio data divided into bands by the FFT unit 22 is supplied to the
analysis unit 24, and the analysis unit 24 analyzes how much audio data is included in each
band. Then, based on the analysis result, the equalizer unit 23 performs a process of increasing
the gain for a band determined to contain a large amount of audio data. Further, the equalizer
unit 23 performs processing to reduce the gain for a band determined to have a small amount of
data including audio data based on the analysis result. The process of reducing the gain may not
be performed, but only the process of increasing the gain may be performed.
[0020]
If it is possible to variably set the frequency band in which the equalizer processing is performed
and the frequency width for changing the gain as the equalizer unit 23, it is variably set based on
the analyzed frequency characteristics, and the frequency width for changing the gain is also
analyzed It may be set variably based on the result. When the frequency band in which the
equalizer processing is performed in the equalizer unit 23 is fixed setting, for example, the gain
of the band closest to the frequency band of the peak determined to contain the most audio data
is increased.
[0021]
The adjustment by the equalizer unit 23 may be performed in real time when reproduction is
actually performed from each reproduction unit or the like. For example, the adjustment may be
performed on a disc loaded in the CD reproduction unit 11 or the MD reproduction unit 12. If it
is possible to read out the recorded audio data prior to reproduction, the read out is performed
and analysis is performed by the DSP unit 20, and the equalizer unit 23 is suitable for
reproduction of the corresponding audio data in advance. It may be set to the state.
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[0022]
The control data of the equalizer unit 23 generated by the control data generation unit 25 is
stored in the memory 30.
The storage in the memory 30 is not only for temporarily storing data in the middle of
processing, but, for example, the storage is left in the memory 30 so that it can be used for the
subsequent reproduction. As a process of using the storage data of the memory 30, for example,
a process of controlling the equalizer unit 23 can be performed by adding the analysis result of
the newly reproduced audio data and the control data stored in the memory 30.
[0023]
The processing shown in the flowcharts of FIGS. 3 to 5 is an example of processing in the case of
performing this addition averaging. Hereinafter, the process will be described. First, as shown in
the flowchart of FIG. 3, audio data is read (step S11), and the read audio data is subjected to fast
Fourier transform to analyze the amount of data for each frequency band. Then, the data for each
frequency component is stored in the memory 30 (step S12). As a frequency band, for example,
100 Hz, 400 Hz, 1 kHz, 4 kHz, 7 kHz, and 10 kHz are set as center frequencies of the respective
bands. Thereafter, adjustment processing is performed in the equalizer unit based on the stored
data (step S13).
[0024]
The flowchart of FIG. 4 is a diagram showing a specific example of the adjustment process in step
S13. First, the gain level for each set frequency band is obtained from the obtained data for each
frequency component, and the data of the gain level is stored in a predetermined area of the
memory 30 prepared in advance (step S21). ). Then, the gain of a certain reference frequency
(for example, 1 kHz) is used as a reference (0 dB), compared with the reference level, and the
adjustment value of the gain is changed based on the comparison (step S22). Specifically, for
example, assuming that the reference level is 35 dB at 1 kHz and 30 dB at 100 Hz, the gain at
100 Hz is -5 dB and the gain at 1 kHz is 0 dB.
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[0025]
Thereafter, it is determined whether or not the gain value falls within the adjustable range at all
frequencies (bands) (step S23). If it is determined that there is a value that does not fall within
the adjustable range, the gain value is corrected (step S24). For example, if the adjustable range
is ± 10 dB and the obtained gain value is +12 dB, +12 dB is corrected to +10 dB.
[0026]
After that, the obtained gain value (the gain value obtained in step S22 or the gain value
corrected in step S14) is stored in the storage area of the memory 30 for adjustment result (here,
the storage area of adjustment result 1). (Step S25). Thereafter, the count value of the counter
configured in the control data generation unit 25 is incremented by one (step S26). Note that this
counter has an initial value of 0. Then, the counter value is also stored in the memory 30 (step
S27), and the adjustment process is ended.
[0027]
When the adjustment processing is completed, the process returns to the flowchart of FIG. 3, and
it is determined whether the number of adjustments performed in step S14 is the first or the
second or later. This determination is made based on whether the count value stored in the
memory 30 is 1 or 2 or more. If it is the first time, the process proceeds to step S16, the
adjustment result is stored as it is in the memory 30, and the process here is ended. If it is the
second time or later, the process proceeds to the averaging process in step S15.
[0028]
The flowchart of FIG. 5 is a diagram showing the averaging process in step S15. Hereinafter, the
process will be described according to the flowchart of FIG. 5. The first frequency at which the
averaging process is performed is set (step S31), and the adjustment result stored in the memory
and the newly detected result (FIG. An averaging process is performed using the adjustment
result 1) described above (step S32). A specific example of the averaging process will be
described later. Then, the gain value as the adjustment result obtained as a result is stored in the
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memory 30 as the adjustment result 2. After that, it is judged whether or not the averaging has
been performed in all frequency bands (step S34). If there is a band that has not been subjected
to the averaging, then the frequency not yet processed is set to the frequency to be averaged (
Step S35) Return to the process of step S32. The setting in step S35 is performed, for example, in
the order of low frequency from among frequencies not set yet. When the process is completed
for all frequency bands, the counter value at this time is stored in the adjustment result 2 (step
S36), and the averaging process here is ended.
[0029]
Here, a calculation example of the averaging process in step S32 will be described. For example,
the gain adjustment value of the storage result stored in the memory 30 is a, the counter value of
the storage result is b, and the adjustment result obtained immediately before Assuming that the
gain adjustment value of 1 is c, the counter value of adjustment result 1 is d, the gain adjustment
value of adjustment result 2 is e, and the counter value of adjustment result 2 is f, the gain
adjustment value e of adjustment result 2 is It can be found by (A × b + c) / d = e However, d = b
+ 1, and as the value of e, for example, round off to the second decimal place. The counter value f
of the adjustment result 2 puts the value of d as it is.
[0030]
FIG. 6 shows the adjustment result 2 (FIG. 6C) obtained by adding and averaging the result (FIG.
6A) stored in the memory 30 and the newly obtained adjustment result 1 (FIG. 6B), and the
adjustment result It is the figure which showed the example of the value in the case of making 2
preserve | save. A to f in FIG. 6 correspond to a to f in the above-described equation. The example
of FIG. 6 is an example in which adjustment is made in units of 0.1 dB based on a frequency of 1
kHz.
[0031]
In this way, by performing adjustment by averaging, every time an audio signal is reproduced, it
is gradually adjusted to an equalizer characteristic that matches the characteristics of the audio
source that is to be reproduced by the device, and is automatically excellent. Regeneration
characteristics can be obtained.
[0032]
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In the above-described embodiment, the audio data handled in the apparatus is the audio data
reproduced by an apparatus for reproducing a medium such as a built-in CD or MD, but the
apparatus for reproducing is any of these audio reproducing apparatuses For example, audio
data input from the outside may be processed.
As the audio data input from the outside, in addition to audio data from a separate reproduction
apparatus, for example, audio data downloaded via the Internet or the like may be input and
processed.
[0033]
In the above-described embodiment, the audio data reproduced by the audio signal source is
applied to the audio device to be subjected to reproduction processing. For example, the audio
data is processed by a data processing device such as a personal computer device. A program
may be installed, and the above-mentioned frequency characteristic adjustment processing of the
present invention may be performed by the program.
[0034]
FIG. 1 is a block diagram showing an example of the overall configuration of a playback device
according to an embodiment of the present invention.
FIG. 5 is a block diagram showing an example of processing configuration in a DSP according to
an embodiment of the present invention. It is the flowchart which showed the example of the
reproduction | regeneration processing by one embodiment of this invention. It is the flowchart
which showed the example of the adjustment process by one embodiment of this invention. It is
the flowchart which showed the example of the addition average by one embodiment of this
invention. It is explanatory drawing which showed the adjustment example theory by one
embodiment of this invention.
Explanation of sign
[0035]
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11: CD playback unit, 12: MD playback unit, 13: memory card reader, 14: analog playback unit,
15: analog / digital converter, 16: input switching unit, 17: digital / analog converter, 18L, 18R:
Amplifier, 19L, 19R: Speaker, 20: DSP unit, 21: FFT (Fast Fourier Transform) unit, 23: Equalizer
unit, 24: Analysis unit, 25: Control data generation unit, 26: Memory
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