JPH0457095A - Electronic type waveform reproducing device - Google Patents

Abstract

PURPOSE:To reduce the capacity of a waveform data storage device and to obtain an inexpensive device by selecting the bit length of sample data to the necessary medium and storing it, adding dummy bits of prescribed bits to the lower level of each sample data which is read out and converting it to sample data of prescribed bit length, and D/A-converting this signal. CONSTITUTION:On an output side of a waveform data storage device 13A, bit converters BH1 - BH24 are provided. That is, bit length of waveform data read out of the device 13A becomes a variable type. As one example thereof, bit length of waveform data of a piano, and bit length of waveform data of a violin are selected to 16 bits and 12 bits, respectively. When bit length of an input signal of a D/A converter provided on each musical tone signal generators G1 - G24 is set to 16 bits, 4 bits becomes short in the case of a violin. The bit converters BH1 - BH24 supply the short bit length to the lower bit side, and waveform data of all musical instruments are made uniform to 16 bits and given to the D/A converter.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to an electronic waveform reproducing device that can be used, for example, in an electronic keyboard instrument or an electronic karaoke device.

"Prior Art J" FIG. 3 shows the configuration of a conventional electronic waveform reproducing apparatus. In the figure, numeral 10 indicates the entire electronic waveform reproducing apparatus.

It is assumed that this electronic waveform reproducing device 10 is made in accordance with the MIDI standard, for example.

Electronic waveform playback device 1 made in compliance with MIDI standards
0 is already a well-known device.

The outline of the configuration is a music data storage device 11, a controller 12,
It is composed of a sound source section 13, a loudspeaker 14, and a control panel 15.

Here, in order to help the understanding of this invention, the musical score information and music data storage device 11 and the sound source section 13 will be briefly explained.

As shown in FIG. 4, the song data refers to a digital signal string obtained by converting each symbol 41, 42, 43, 44, . . . , 52 of a musical score for playing a song into predetermined digital codes.

The order of conversion into digital symbols is performed for each part.

In other words, staff A shown in FIG. 4 is the treble part, and staff B is the low temperature part. Generally, in the treble part shown on staff A, the melody is played by a pitched instrument such as a piano, guitar violin, flute, or clarinet.

Furthermore, in the bass part shown on staff B, the rhythm, or generally the accompaniment, is played by unpitched instruments such as the top cymbal, high hat, and drums.

In this example, two par I.
The musical note symbols 41, 42, 43, etc. on each staff are converted into digital codes in order from the beginning.

After converting all staves A into digital codes, next, staff B is converted into digital codes from the beginning, this is repeated for the number of parts, and the digital codes are written into a storage means such as an IC card or ROM.

FIG. 5 shows an example of musical score information. The meaning of each symbol in the score information is as follows.

SOT: Identification code indicating the beginning of the song, TMP: Identification code specifying the tempo of the song, STI~5T24: Note information for each part, rNs: Specifying the instrument sound, EOC: End of the part, EOT: End of the song For example, the identification code shown in the song data storage device 11 is 24 for each part as shown in FIG.
storage areas MI, M2.

M3. M, . . . Mg2 are provided, and musical score information is stored in storage areas M, . . . M2 . M,, M4...stored in Mz4.

The musical score information written in the music data storage device 11 is read out in parallel in sequence from the first address for each part by a controller 12 constituted by a microcomputer.

In other words, the first address of each storage area M, , M, , M3...Mg2 is read out sequentially, and when the first address of all storage areas M+ -Mg2 is read, the second address is read for each storage area. be done. In this way, the information of each part is read out in a time-division manner and sent to the sound source section 13. The sound source section 13 includes a waveform data storage device 13A and a waveform data storage device 13A.
Consisting of musical tone signal generators G, ~G24, which convert the waveform data read from A into analog signals by DA conversion, and a mixer 13B, which mixes the analog signals output from the musical tone signal generators G, ~G24. be done.

The controller 12 decodes the song data read from the song data storage device, and according to the decoding result, the waveform data storage device 13A
Reads the waveform data stored in.

In other words, the song data does not indicate the type of instrument, but the codes ST1 to ST5.
T24 (see FIG. 5) is attached, and the waveform data of various musical instruments stored in the waveform data storage device 13A is read out using the code representing the type of the musical instrument.

The waveform data storage device 13A stores data for one cycle or half a cycle of waveforms of various musical instruments in the form of digital code strings, and converts the waveform data at a speed corresponding to the pitch data attached to the song data. A digital signal string having a frequency corresponding to the musical note and waveform information is output. This digital signal train is generated by the musical tone signal generator CI''-
G z a and converts it into a musical tone signal having the timbre of each part.

In this way, each of the musical tone signal generators 01 to G24 outputs a musical tone signal according to the musical score information. This musical tone signal is output in the form of a pulse modulation signal having a duty ratio of 1/the number of parts, for example, as shown in FIG. and send the mixed output signal to the low frequency amplifier 1.
Public address system 1 composed of 4A and speaker 14B
4, it is emitted as a sound.

Musical sound playback devices that operate according to the MIDI standard store musical score information, so the amount of information is only a fraction of the amount of digitally encoded and stored actual music. It has the feature of being able to play music.

As described above, the tone of each musical instrument is generated according to the waveform data read from the waveform data storage device 13A provided in the sound source section 13.

FIG. 8 shows an example of waveform data. D+, Dz.

D3...D, , respectively indicate sample data forming the waveform data. Each sample data D.

~D, reproduces one cycle or half cycle of a waveform with each timbre, and by varying the readout speed, the pitch is controlled, and by controlling the readout time, the sound attached to the note can be adjusted. Length is specified.

"Problem to be solved by the invention" Sample data DI, D2D3 that constitutes waveform data
...Since Dh is DA-converted by a DA converter, the bit length of the data is specified to be a constant bit length, regardless of the difference in waveform. Therefore, if a 16-bit data length is required to reproduce a complex waveform such as that of a piano, the data length of other musical instruments must also be 16 bits.

For this reason, data of a monotonous waveform such as that of a percussion instrument is written to the waveform data storage device with a constant data length of, for example, 16 bits.

To express a monotonous waveform, the data bit length may be short. For example, in order to reproduce a signal of a single frequency, it is sufficient to repeat "1" and I' OJ, so a data length of 1 bit is sufficient.

In this way, in the past, the bit length of the waveform data of the sound of the instrument to be reproduced that had to have the longest bit length was used as the standard, and the waveform data of all the sounds of all instruments were calculated using this bit length. is written.

For this reason, the storage capacity becomes large and the cost inevitably increases.

Incidentally, the electronic karaoke performance device sold by the applicant's company stores 80 types of waveform data in a 32 Mbit (4 Mbyte) memory.

Such a large capacity memory is expensive and has the drawback of increasing the cost of the entire device.

An object of the present invention is to reduce the capacity of a waveform data storage device and to provide an electronic playback device that can be manufactured at low cost.

"Means for Solving the Problem" In this invention, a plurality of sample data are stored in a storage device as waveform data of signals having various tones, and this waveform data is read out at a speed corresponding to the frequency of the sound to be reproduced. In an electronic waveform playback device that performs DA conversion on read waveform data to obtain an analog signal with a desired waveform and frequency and reproduces musical tones, the bit length of the sample data that makes up the waveform data is set to the minimum necessary for each waveform. A specified bit length is selected and stored, and a predetermined dummy bit is added to the lower part of each sample data read at the time of reading, converting it into sample data with a specified bit length, and the signal with this specified bit length is converted to DA. It is configured to do so.

According to the configuration of the present invention, waveform data of a simple waveform can be written in the waveform data storage device as sample data with a short bit length. Therefore, the waveform data storage device can be configured with a memory having a small storage capacity.

"Embodiment" FIG. 1 shows an embodiment of the present invention. The feature of this invention is that there is a pin on the output side of the waveform data storage device 13A.
- The point is that converters BH, to BH24 are provided.

That is, in this invention, the bit length of the waveform data read from the waveform data storage word M 13 A is made variable.

As an example, the bit length of piano waveform data is 16 bits, the bit length of violin waveform data is 12 bits, the bit length of flute waveform data is 8 bits, and the bit length of percussion instrument waveform data is 8 bits.

If the bit length of the input signal of the DA converter provided in each musical tone signal generator G, -CZ4 is 16 bits, there will be a shortage of 4 bits for the violin and 8 bits for the flute and percussion instruments.

The bit converters BH, .

FIG. 2 shows an example of a configuration of bit converters B I-I, ~BI (24). In the figure, the configuration of one bit converter BH, is shown. In this example, the bit converter BH,
. . , and an OR gate group 13C connected to the input terminals I, -I+6 of the lower 8 bits of the latch circuit RH.

One input terminal of each OR gate provided in the OR gate group 13C is connected to the common potential point 13D, and unless H logic is applied to the other input terminal of the OR gate, the input terminal I of the lower 8 bits of the latch circuit RH is connected.

~116 are configured to input L logic.

When, for example, 8-bit waveform data is read out from the waveform data storage device 13A, this waveform data is inputted to the input terminals 11-I of the latch circuit RH as a signal of the upper 8 bits. At this time, the input terminals I, ~I of the latch circuit RH
L logic is applied to I6 by the OR gate group 13C, and 8-bit dummy data with a value of O is added to the lower part of the upper 8 bits of waveform data, and the data is latched into the latch circuit RH.

In addition, when 12-bit waveform data is read from the waveform data storage device 13A, the input terminals 11 to 1 of the latch RH
Waveform data is input to 1□, and input terminals 1□3 to 116
The lower 4 bits are given L logic from the OR gate group 13C, and 4 bits of dummy data with a value of O are added.

When 16-bit waveform data is read from the waveform data storage device 13A, the 16-bit waveform data is input to all input terminals 11-116 of the latch circuit RH and latched.

Although the top view shows the case where the OR gate group 13C is provided in the lower 8 bits, it is not limited to 8 bits, and may be selected depending on the bit length of the waveform data stored in the waveform data storage device 13A.

"Effects of the Invention" As described above, according to the present invention, the bit length of the waveform data stored in the waveform data storage device 13A is selected to be the minimum necessary number of bits according to the waveform, so that monotonous waveform data is The bit length can be shortened.

As a result, since the storage capacity of the waveform data whose bit length is selected to be short can be reduced, the overall capacity of the memory constituting the waveform data storage device 13A can be reduced, and cost reduction can be expected accordingly. .

By the way, conventionally it takes 32M to store 80 types of waveform data.
Although this required a memory of 174 to 115 bits, the capacity could be reduced to 174 to 115 bits by applying this invention.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a connection diagram showing an example of the configuration of a bit converter used in the present invention, and FIG. 3 is a block diagram for explaining the conventional technology. Figures 4 and 5 are diagrams for explaining the old language data,
Figure 6 is a diagram for explaining the storage status of song data, Figure 7
The figure is a waveform diagram showing the waveform of the musical tone output from the musical tone generator, and FIG. 8 is a waveform diagram for explaining the waveform data read from the waveform data storage device. 10; electronic waveform reproducing device; 11: song data storage device;
12: Controller, 13: Sound source section, 13A: Waveform data storage device, BH, ~BH2,: Bit converter, G■ ~ G24
; musical tone signal generator, 13B: mixer, 14: loudspeaker.

Claims (1)

[Claims] (1) A. Store multiple sample data in a memory as waveform data of signals with various tones, reproduce this waveform data or read it out at a speed corresponding to the frequency of the sound, and use the read waveform data as DA. In an electronic waveform reproducing device that converts an analog signal with a desired waveform and frequency and reproduces musical tones, A predetermined number of dummy bits are added to the lower order of each sample data read out, and the sample data is converted into sample data with a specified bit length, and the signal having this specified bit length is converted from analog to digital. An electronic waveform reproducing device characterized by comprising: