JP3789358B2 - Electronic sound generation method and apparatus, and portable device using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electronic sound generator for playing music using waveform data stored in a storage device, and a portable device (for example, a mobile phone, a synthesizer, a PDA, etc.) using the electronic sound generator.
[0002]
[Prior art]
Conventionally, as a method of generating an electronic sound using waveform data stored in a storage device, all are designed by hardware, and software is used by using a digital signal processing device such as a DSP (digital signal processor). Arithmetic processing methods have been used. Recently, in order to increase the number of simultaneous pronunciations and to cope with various acoustic effects, the calculation contents and calculation order have become complicated. Accordingly, it is becoming difficult to configure all signal processing by hardware from the viewpoint of the design period and change of processing contents.
[0003]
For this reason, a method of processing by software using a digital signal processing apparatus has come to be widely used because a complicated calculation order can be developed as a program.
[0004]
FIG. 3 is a diagram showing a configuration of a conventional electronic sound generator using a digital signal processing device, and FIG. 4 is a timing chart for explaining the operation thereof.
[0005]
In FIG. 3, the digital signal processing circuit 13 includes waveform data for required music stored in a waveform memory 12 such as a ROM, and sound parameters corresponding to the type and scale of the instrument from the sound parameter input circuit 11. Are entered. The digital signal processing circuit 13 starts arithmetic processing in synchronization with the sampling signal i input from the sampling signal generation circuit 15 based on the input waveform data and sound parameters. Then, a predetermined amount of computation is performed within the sampling period T to obtain sound data to be output, and the computation processing result data, that is, sound data is input to the computation result output circuit 16.
[0006]
The sampling signal i is output every fixed period T (T1 to T7), and each predetermined calculation process is performed within this period T. This period T is 22.7 μs (= 1 / 44.1 kHz) as in, for example, CD. In response to the sampling signal i, the digital signal processing circuit 13 starts the operation, and inputs the operation processing result data v to the operation result processing circuit 16 at the time t1 ′ to t7 ′ when the operation ends. In synchronization with the next sampling signal i, the stored arithmetic processing result data v is output from the arithmetic result output circuit 16 as sound data vi. Note that iii indicates that calculation processing is being performed.
[0007]
[Problems to be solved by the invention]
The amount of computation that can be performed within the sampling period T is determined by the period T and the operating frequency of the LSI in which the electronic sound generator is built. In FIG. 4, when the calculation is started by the sampling signal i at the time point t1, and the required calculation ends at the time point t1 ′ within the cycle T1, the operation is normal. However, when the calculation is started by the sampling signal i at the time point t2 and the required calculation is not completed within the cycle T2, the processing is performed by entering the subsequent cycle T3, and the calculation is completed at the time point t2 ′. The arithmetic processing result data is output in synchronization with the sampling signal i at time t4. At time t3, the sound data already output at time t2 is output again.
[0008]
Thereafter, in the cycle T4, an operation that should be originally performed in the cycle T3 is processed, and in each cycle after the cycle T5, similarly, an operation that should be performed in the previous cycle is processed. Thus, when a required calculation does not end within a certain period, the calculation process to be performed in each subsequent period is delayed in time and is performed in the subsequent period. This delay in calculation processing is accumulated every time a state where a required calculation does not end within one cycle occurs.
[0009]
Since the delay in the arithmetic processing leads to a large shift in the entire music, the maximum calculation amount cannot exceed the sampling period T.
[0010]
In order to avoid such a situation, it is only necessary to decrease the sampling frequency to increase the period T and increase the amount of calculation processing per unit time.
[0011]
However, in order to output a richer timbre, it is necessary to increase the sampling frequency to be output, so it is not preferable to increase the sampling period T. Further, increasing the amount of calculation processing per unit time increases the operating frequency of the LSI in which each of these components is incorporated. In this case, however, the power consumption of the LSI increases and the required area increases. Since it will become large, it is not preferable and it becomes difficult to apply especially to a portable apparatus.
[0012]
Therefore, the present invention can generate a richer timbre without increasing the sampling period and without particularly increasing the operating frequency of the LSI, and can be used suitably for a portable device. And an apparatus and a portable device using the same.
[0013]
[Means for Solving the Problems]
The electronic sound generation method according to claim 1 starts computation processing based on waveform data and sound parameters by a computation start signal, outputs computation processing result data when predetermined computation processing ends, and performs the computation When processing ends during a period between sampling signals having a fixed period, the calculation start signal is generated in synchronization with the sampling signal, and the calculation process does not end during a period between sampling signals having a fixed period. In some cases, the calculation start signal is output after the calculation process is completed.
[0014]
The electronic sound generation method according to claim 2 is the electronic sound generation method according to claim 1, characterized in that the arithmetic processing result data is held and output in synchronization with the sampling signal.
[0015]
According to a third aspect of the present invention, there is provided an electronic sound generating device that starts a calculation process by a calculation start signal based on a waveform storage unit that stores waveform data, waveform data input from the waveform storage unit, and a sound parameter. A digital signal processing means for outputting a calculation processing result data when a predetermined calculation processing is completed, a sampling signal generating means for outputting a sampling signal of a fixed period, and the calculation processing signal; When the sampling signal is input, and when the sampling signal at a certain point in time (hereinafter, the sampling signal) is input and the calculation processing signal is not output, the calculation start signal is synchronized with the sampling signal. When the signal is being supplied to the digital signal processing means and the calculation processing signal is being output, the calculation is completed. And a synchronization on / off means for supplying the computation start signal to the digital signal processing means, and holding the computation processing result data inputted from the digital signal processing means, as sound data in synchronization with the sampling signal And a calculation result output means for outputting.
[0016]
According to a fourth aspect of the present invention, there is provided an electronic sound generating device that starts a calculation process by a calculation start signal based on a waveform storage unit that stores waveform data, waveform data that is input from the waveform storage unit, and a sound parameter. A digital signal processing means for outputting a computation end signal and outputting computation processing result data when the computation processing is completed, a sampling signal generating means for outputting a sampling signal of a fixed period, the computation end signal and the sampling signal When a predetermined calculation process is started and ended during a period between a sampling signal at a certain time point (hereinafter, the sampling signal) and the immediately preceding sampling signal, the synchronization signal is synchronized with the sampling signal. An operation start signal is supplied to the digital signal processing means, and the sampling signal and the immediately preceding sampling signal are supplied. A synchronization on / off means for supplying the calculation start signal to the digital signal processing means after the calculation end signal is input when a predetermined calculation process is started and not ended during a period between the pulling signals; Computation result output means for holding computation processing result data input from the digital signal processing means and outputting as sound data in synchronization with the sampling signal is provided.
[0017]
The electronic sound generator according to claim 5 is the electronic sound generator according to claims 3 and 4, wherein the calculation result output means holds the calculation processing result data input from the digital signal processing means. The operation processing result data being overwritten is overwritten with new operation processing result data.
[0018]
According to a sixth aspect of the present invention, there is provided a portable device comprising the electronic sound generator according to any of the third to fifth aspects.
[0019]
According to the electronic sound generation method and apparatus of the present invention, by performing a part of calculation processing when the calculation amount is large in a sampling period with a small calculation amount, the entire song is richer without causing almost any deviation. Sound output can be realized.
[0020]
In addition, it is possible to increase the number of processing that can be substantially calculated compared to the conventional one that has been adjusted to the maximum value by keeping the average value of the time required for calculation processing of sound data within the sampling period. It can output richer sound. In addition, since the sampling frequency can be increased, the sound quality can be improved.
[0021]
In addition, since the operating frequency can be lowered, it can be used in a circuit operating at a low speed, the power consumption of the LSI realizing the present invention can be reduced, and the mounting area on the substrate can be reduced. Therefore, it is effective for use in portable devices that are required to be downsized and have low power consumption.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of an electronic sound generating method and apparatus according to the present invention will be described with reference to FIG. 1 showing its configuration and FIG. 2 which is a timing chart thereof.
[0023]
In FIG. 1, the electronic sound generator of the present invention mainly includes a sound parameter input circuit 11, a waveform memory 12, a digital signal processing circuit 13, a synchronous on / off circuit 14, a sampling signal generation circuit 15, and a calculation result output. A circuit 16 is included. Each of these components is controlled by a control device such as a CPU (not shown).
[0024]
First, the sound parameter input circuit 11 inputs sound parameters composed of data such as instrument type and scale to the digital signal processing circuit 13, and the sound parameters instructed by the CPU or the like are selected and output.
[0025]
The waveform memory 12 is preliminarily inputted with a PCM sound source signal to be processed (hereinafter also referred to as waveform data) via an input / output means (not shown), and a read-only memory (ROM) is used. It is done. As the waveform data, various data for each musical instrument are stored in association with the memory address.
[0026]
The digital signal processing circuit 13 performs a required calculation process based on the input sound parameters and waveform data. The arithmetic processing of the digital signal processing circuit 13 is started in response to the arithmetic start signal ii from the synchronous on / off circuit 14, and performs a group of arithmetic processing output as sound data. When this batch of arithmetic processing is completed, the arithmetic end signal iv is supplied to the synchronous on / off circuit 14 and the arithmetic processing result data v is supplied to the arithmetic result output circuit 16. Note that an in-computation signal iii may be output together with or instead of the computation end signal iv.
[0027]
The sampling signal generation circuit 15 outputs a sampling signal i having a predetermined constant period (for example, 22.7 μs) to the synchronous on / off circuit 14 and the operation result output circuit 16. With respect to this sampling period, the time required for the group of arithmetic processes in the digital signal processing circuit 13 may be such that the maximum value of the time required for the group of arithmetic processes may exceed the sampling period, but the average value thereof. Are set to be within the sampling period. That is, the maximum value> sampling period> average value is set.
[0028]
The synchronization on / off circuit 14 outputs the calculation start signal ii synchronized with the input sampling signal i, or waits for the calculation end signal iv input after the sampling signal i, and outputs the calculation start signal ii. This circuit determines whether to output. The timing at which the calculation start signal ii is output is determined by whether or not a group of calculation processing in the digital signal processing circuit 13 is performed within one sampling period.
[0029]
The calculation result output circuit 16 includes a register for holding calculation processing result data v output asynchronously from the digital signal processing circuit 13, and the calculation processing result data v held in the register is sampled by the sampling synchronization signal i. Is read out in synchronization with and output as sound data vi. This register has a format that retains the same data even when the data is read and is overwritten when new data is input.
[0030]
Now, the operation of the electronic sound generator of FIG. 1 will be described with reference to the timing chart of FIG.
[0031]
The sampling signal i is generated every predetermined constant period T (T1 to T7). In the first period T1, when the sampling signal i is output at time t1, the synchronization on / off circuit 14 generates an operation start signal ii in synchronization with the sampling signal i and inputs it to the digital signal processing circuit 13. In response to the calculation start signal ii, the digital signal processing circuit 13 immediately starts the calculation process based on the sound parameter and the waveform data, and ends the predetermined calculation process at a predetermined time t1 ′. Note that an arithmetic processing signal iii indicating that arithmetic processing is being performed may be supplied from the digital signal processing circuit 13 to the synchronous on / off circuit 14.
[0032]
At the time point t1 ′ when the operation is completed, the operation end signal iv is input to the synchronous on / off circuit 14 and the operation processing result data v is input to the operation result output circuit 16 and held. The calculation processing result data v held in the calculation result output circuit 16 is output from the calculation result output circuit 16 as sound data at time t2 in synchronization with the next sampling signal i. In this way, it is a normal form that required calculation processing is performed within one cycle T1.
[0033]
Next, in the second period T2, since the calculation process is completed within the previous period T1, the calculation start signal ii is output synchronously at the time t2 when the sampling signal i is output, and the calculation process is started. The
[0034]
An example is shown in which the amount of computation processing in this cycle T2 is large, the computation processing does not end within the cycle T2, and the computation processing ends at the time point t2 ′ by biting into the cycle T3.
[0035]
In this case, since the new calculation processing result data v has not yet been obtained at the time t3 when the sampling signal i of the next cycle T3 is output, the previous calculation result output circuit 16 holds the previous calculation result. Output data instead. Thereby, loss of sound data is prevented.
[0036]
When the calculation process is completed at time t2 ′, the calculation end signal iv is immediately output, and the calculation start signal ii is generated by the calculation end signal iv and the sampling signal i of the cycle T3 (time t3). Thereby, the calculation process for the cycle T3 is started. At the same time, operation processing result data v is output, and the register of the operation result output circuit 16 is overwritten with new data. Then, the processing result for the cycle T2 is output at the time t4 with a delay of one cycle T.
[0037]
Even if the calculation processing time in the cycle T3 is within one cycle T, the start time has already fallen into the cycle T3, so that the calculation end time t3 ′ is also in the cycle T4. When the calculation for the cycle T3 ends at this time t3 ′, the calculation start signal ii for the cycle T4 is output, and the calculation process is started. At the same time, the operation processing result data v is output, and the register of the operation result output circuit 16 is overwritten with new data. Then, the processing result for the cycle T3 is output at time t5 with a delay of one cycle T.
[0038]
The calculation processing time for the period T4 has become considerably short, but is still within the period T5. For this reason, when the calculation for the cycle T4 ends at the time point t4 ′, the calculation start signal ii for the cycle T5 is output, and the calculation process is started. At the same time, the operation processing result data v is output, and the register of the operation result output circuit 16 is overwritten with new data.
[0039]
In the cycle T5, the calculation for the cycle T4 is finished early (time t4 ′), the calculation processing time for the cycle T5 is also shortened, and the calculation processing is finished at the time t5 ′ in the cycle T5.
[0040]
In this case, the calculation end signal iv is output to the synchronous on / off circuit 14 at time t5 ′, but the second calculation end signal iv is input to the synchronous on / off circuit 14 within the same period T5. It will be. The generation of the two computation end signals iv within the same cycle indicates that the processing that has entered into the cycle T3 following the cycle T2 has been recovered at this point.
[0041]
Therefore, the two calculation end signals iv in the same period T5 are ignored, and the calculation start signal corresponding to this is not generated (indicated by a broken line in the figure).
[0042]
On the other hand, in accordance with the end of the arithmetic processing at time t5 ′, the arithmetic processing result data v is also output. Therefore, the arithmetic processing result data output at time t4 ′ is overwritten with the arithmetic processing result data output at time t5 ′. As a result, the calculation processing result data output at the time t4 ′ is not output as sound data. As the sound data for the cycle T5, the calculation processing result data output at the time point t5 ′ is output.
[0043]
After the period T6, the calculation processing result for the period ends during the period, so the operation is the same as the operation in the period T1.
[0044]
In the present invention, as described above, the maximum value of time required for a group of arithmetic processing in the digital signal processing circuit 13 with respect to the sampling period T may exceed the sampling period as exemplified by the period T2. . If the computation processing time in that cycle has sunk into the next cycle, it is absorbed by the subsequent cycle. In order to perform this absorption, an average value of time required for a group of calculation processing is set so as to be within a sampling period. That is, the maximum value> sampling period> average value is set.
[0045]
In general, in an electronic sound generator as in the present invention, the amount of calculation processing as a group is increased at the initial stage of a series of sound data accompanied by parameter processing when a specific sound is generated. Just do it. The frequency of occurrence of such a large amount of calculation processing is very low, about once every several thousand to several tens of thousands.
[0046]
In the method of the present invention, when an arithmetic process exceeding the sampling period T occurs, the same sound data is used twice, and one sound data is not used. However, in the present invention, the sampling period T is set so as to be shorter than the maximum value of the time required for a group of arithmetic processes and longer than the average value thereof, so that the delay of the arithmetic process is the subsequent period. Therefore, the deviation of the entire song does not occur. In addition, since the frequency of occurrence is extremely low, the influence on the sound quality can be almost ignored.
[0047]
As in the present invention, it can be said that the effects obtained by the present invention are sufficiently large, such as improvement in sound quality by setting a time required for a group of calculation processes for the sampling period T.
[0048]
The sound parameter input circuit 11, the waveform memory 12, the digital signal processing circuit 13, the synchronization on / off circuit 14, the sampling signal generation circuit 15, and the calculation result output circuit 16 are each independently an LSI together with a control device (not shown). It is also possible to configure the LSI, and it is also possible to build it into an LSI by any combination thereof.
[0049]
【The invention's effect】
According to the present invention, it is possible to realize a richer sound output with almost no deviation as a whole song by performing a part of calculation processing when the calculation amount is large in a sampling period with a small calculation amount. it can.
[0050]
In addition, it is possible to increase the number of processing that can be substantially calculated compared to the conventional one that has been adjusted to the maximum value by keeping the average value of the time required for calculation processing of sound data within the sampling period. It can output richer sound. In addition, since the sampling frequency can be increased, the sound quality can be improved.
[0051]
In addition, since the operating frequency can be lowered, it can be used in a circuit operating at a low speed, the power consumption of the LSI realizing the present invention can be reduced, and the mounting area on the substrate can be reduced. Therefore, it is effective for use in portable devices that are required to be downsized and have low power consumption.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an electronic sound generator according to an embodiment of the present invention.
FIG. 2 is a timing chart of FIG.
FIG. 3 is a diagram showing a configuration of a conventional electronic sound generator.
4 is a timing chart of FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 Sound parameter input circuit 12 Waveform memory 13 Digital signal processing circuit 14 Synchronization on / off circuit 15 Sampling signal generation circuit 16 Calculation result output circuit

Claims (6)

Calculation processing based on waveform data and sound parameters is started by a calculation start signal, and calculation processing result data is output when a predetermined calculation processing is completed,
When the arithmetic processing ends during a period between sampling signals having a fixed period, the arithmetic start signal is generated in synchronization with the sampling signal,
When the arithmetic processing does not end during a period between sampling signals having a constant period, the arithmetic start signal is output after the arithmetic processing ends.
An electronic sound generating method characterized by the above. 2. The electronic sound generation method according to claim 1, wherein the arithmetic processing result data is held and output in synchronization with the sampling signal. Waveform storage means for storing waveform data;
Based on the waveform data input from the waveform storage means and the sound parameters, calculation processing is started by a calculation start signal, a calculation processing signal is output, and calculation processing result data is output when a predetermined calculation processing is completed. Digital signal processing means for outputting
Sampling signal generating means for outputting a sampling signal of a fixed period;
When the arithmetic processing signal and the sampling signal are input, and when the sampling signal at a certain time point (hereinafter, the sampling signal) is input and the arithmetic processing signal is not output, it is synchronized with the sampling signal. The computation start signal is supplied to the digital signal processing means, and when the computation processing signal is output, the computation start signal is supplied to the digital signal processing means after the computation is completed. Means,
An electronic sound generator comprising: arithmetic result output means for holding arithmetic processing result data input from the digital signal processing means and outputting the result as sound data in synchronization with the sampling signal. Waveform storage means for storing waveform data;
Based on the waveform data input from the waveform storage means and the sound parameters, the calculation processing is started by the calculation start signal, and when the predetermined calculation processing is completed, the calculation end signal is output and the calculation processing result data is output. Digital signal processing means for
Sampling signal generating means for outputting a sampling signal of a fixed period;
When the calculation end signal and the sampling signal are input, and a predetermined calculation process is started and ended during a period between a sampling signal at a certain time point (hereinafter, the sampling signal) and the sampling signal immediately before the sampling signal, The calculation start signal is supplied to the digital signal processing means in synchronization with the sampling signal, and when a predetermined calculation process is started and not ended during the period between the sampling signal and the immediately preceding sampling signal, Synchronization on / off means for supplying the calculation start signal to the digital signal processing means after the calculation end signal is input;
Calculation result output means for holding calculation processing result data input from the digital signal processing means and outputting as sound data in synchronization with the sampling signal;
An electronic sound generating device comprising: The calculation result output means holds calculation processing result data inputted from the digital signal processing means, and the held calculation processing result data is overwritten by new calculation processing result data. The electronic sound generator according to claim 3. A portable device comprising the electronic sound generator according to claim 3.

Images