JPH0670398

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DESCRIPTION JPH0670398
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to
digital signal processing of digital audio devices, and more particularly to a digital audio device
suitable for enhancing the presence effect in music reproduction and the like.
[0002]
2. Description of the Related Art Heretofore, many of the block diagrams shown in FIG. 2 have
been provided as digital signal arithmetic processing of digital audio signals to obtain presence
effects such as a surround effect of music reproduction.
[0003]
In the figure, 1 is an input terminal of an analog audio signal, 2 is an A / D conversion circuit for
converting an analog signal to a digital signal, 3 is a digital filter, and 8 is a digital audio signal
processing for processing digital audio signals. A circuit (hereinafter simply referred to as DASP),
10 is a digital filter, 11 is a D / A conversion circuit for converting a digital signal into an analog
signal, 12 is an output terminal of an analog audio signal, 20 is a digital signal and converted into
a digital filter 3 , For example, a digital signal of 16 to 18 bit number, 21 is an analog signal
adder
[0004]
The digital audio apparatus configured in this manner converts the analog audio signal applied to
the input terminal 1 into a digital signal by the A / D conversion circuit 2 and supplies the digital
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signal to the DASP 8 through the digital filter 3 for arithmetic processing I was
[0005]
When the digital signal is, for example, an output reproduction signal from a CD player or the
like, a 16 to 18 bit digital signal 20 is generally supplied to the DASP 8 to add a reverberation
component or a surround effect to add a presence effect. A digital audio signal that takes this
presence effect into consideration is converted to an analog signal by the D / A conversion circuit
11 through the digital filter 10, and the analog signal of the input original sound that is basically
not processed is added by the adder 21 to obtain a music source. It was playing the sense of
sound of music with a combined presence effect.
[0006]
However, at the recording site of the analog audio signal, usually, some reverberation
components are included, or the recording is performed taking into account the reverberation
components actively.
[0007]
For this reason, the above-mentioned digital audio apparatus is mixed with the reverberation
component of the original input sound and the presence effect including the reverberation
component processed by DASP 8 to be mixed and reproduced. There is a drawback that you can
feel discomfort when listening to music
[0008]
When it is intended to actively change the tone of the reproduced sound in the arithmetic
processing of DASP8, low-level components such as the reverberation component of the input
original sound are included, so that the tone change due to DASP8 is sufficiently applied. There is
also a drawback that you can not do it.
[0009]
The present invention has been made in view of the above-described point, and the object of the
present invention is to eliminate the disadvantages of the prior art and to reduce the number of
bits of the input digital audio signal by providing a bit truncation circuit. It is an object of the
present invention to provide a digital audio device for processing arithmetic signals in DASP8.
[0010]
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SUMMARY OF THE INVENTION A digital audio apparatus according to the present invention is
an input digital audio signal in a digital audio apparatus for obtaining a presence effect of music
reproduction by processing digital audio signals with a digital audio signal processing circuit. A
bit truncation circuit for truncating the number of bits is provided, and an output digital signal of
the bit truncation circuit is supplied to a digital audio signal processing circuit.
[0011]
According to the present invention, the low-order bit discarding circuit is provided in the digital
audio signal arithmetic processing circuit, and the low-order bit is added before the surround
effect or any reverberation component etc. are added by DASP. The digital audio signal
arithmetic processing is performed by converting into a digital signal of a small number of bits.
[0012]
By discarding the lower bits in this way, it is possible to eliminate the low level signal
components of the reverberation component and the fundamental wave component contained in
the input original sound, and therefore, the presence processing can be obtained in pure state by
the arithmetic processing by DASP. It is possible to freely add the presence effect desired by the
listener or the presence effect suited to the music source.
[0013]
That is, it is possible to create a feeling of sound field of the desired music reproduction, and it is
also possible to produce an arbitrary tone change.
[0014]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of a digital audio
apparatus according to the present invention will be described with reference to the block
diagram of FIG.
The same reference numerals are given to the same parts as those in the conventional example
and the description thereof is omitted.
[0015]
In the figure, 4 is an input terminal of a digital audio signal from the music source side, 5 is a
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switch between the digital audio input signal and an analog audio input signal supplied to the
input terminal 1, 6 is an input digital audio signal 7 is a digital audio signal with a reduced
number of bits, and 9 is an adder for adding the output digital signal of the DASP 8 and the
digital signal on the DASP 8 input side.
[0016]
The analog audio signal supplied from the music source side to the input terminal 1 is converted
into a digital signal by the A / D converter circuit 2 as in the prior art, and supplied to the switch
5 through the digital filter 3.
On the other hand, a digital audio signal supplied from the music source side is supplied from the
input terminal 4 to the switch 5.
[0017]
When the audio signal to be recorded by the digital audio device is an analog signal, the switch 5
is set to the analog audio signal input terminal 1 by setting the digital audio device to the analog
signal recording mode. The analog audio signal which is connected to the side and converted into
the digital signal is supplied to the bit truncation circuit 6.
[0018]
When the digital audio apparatus is set to the digital signal recording mode, the switch 5 is
connected to the input signal side from the input terminal 4 of the digital audio signal, and the
digital audio signal is transmitted to the bit truncation circuit 6. Supplied.
[0019]
The bit truncation circuit 6 truncates the lower bits constituting the low level of the input digital
audio signal component, and the conventional 16-18 bit digital signal is converted to, for
example, a 12-14 bit digital audio signal.
[0020]
That is, since the reverberation component of the input original sound digital audio signal is
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lower in level than the fundamental wave component and decays with time, the digital audio
signal 7 with less reverberation components is obtained by discarding the lower bits of the input
original sound. be able to.
At the same time, the low-level signal component of the fundamental wave component is also
discarded, so that the timbre of the music has the characteristics of the original sound, but it
becomes a clean digital audio signal 7 that does not express much of the details of the music.
[0021]
The digital audio signal 7 with the low-order bits cut off is supplied to the DASP 8 and the digital
audio signal arithmetic processing is applied to the contents suitable for the listener's preference
and music source to add the presence effect of music reproduction. The digital audio signal to
which the presence effect is added is supplied to the adder 9.
On the other hand, the adder 9 is supplied with a bit-cut digital audio signal 7 which does not
pass through the DASP 8 and is added to the digital audio signal to which the presence effect is
added.
[0022]
The digital audio signal added by the adder 9 is converted to an analog audio signal by the D / A
conversion circuit 11 through the digital filter 10 and output to the output terminal 12.
[0023]
As described above, the reverberation components predetermined by the DASP 8 are added
without being influenced by the reverberation components contained in the input original sound
audio signal, and the presence effect without a sense of discomfort can be obtained.
In addition, it is also possible to change the tone color etc.
[0024]
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As described above, the digital audio apparatus according to the present invention can reduce the
reverberation component contained in the audio signal of the input original sound by discarding
the number of lower bits of the digital signal, This digital audio signal with a small number of bits
can be arithmetically processed by DASP to give the presence effect of a freely reproduced signal,
and the timbre etc. can also be changed arbitrarily large, so the sound field feeling of music
reproduction can be obtained. There is an effect that it can listen without discomfort.
[0025]
Furthermore, since the number of bits of the digital audio signal obtained by rounding off the
lower bits input to the DASP is small, the digital audio signal processing operation of the DASP
can be processed at high speed.
[0026]
In addition, since the presence effect of free music reproduction can be created without being
influenced by the reverberation component included in the input original sound, it is installed
especially in the vehicle interior with a high degree of sealing of the acoustic space. A car audio
system for vehicles has a great effect and can be used as an effective function.
[0027]
In addition, it has excellent features such as simple structure and easy implementation because it
can be configured inexpensively.
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