JP2000066679A - Wave form compressing and expanding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the quality of a wave form compressed or expanded in a time-axial direction. SOLUTION: In this device 100, plural wave forms different in music performing speeds are stored in a ROM 11, and one wave form is selected out of the plural wave forms stored in the ROW 11, based on compressibility or expansibility gained by an operation element group 15. The selected wave form is compressed or expanded in a time-axial direction to provide a wave form having a music performing speed corresponding to the compressibility or the expansibility.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waveform compression / expansion apparatus for compressing or expanding a waveform in a time axis direction.

[0002]

2. Description of the Related Art Conventionally, a compression / expansion rate for compressing or expanding a waveform in a time axis direction is set, and a basic waveform (hereinafter, referred to as an original waveform) is set in a time axis direction based on the set compression / expansion rate. 2. Description of the Related Art Waveform compression / expansion devices that compress or expand are known.

[0003]

However, when the original waveform is compressed or expanded based on the set companding rate, if the set companding rate is extremely far from 100% (1: 1), ie, When the degree of compression or expansion is extremely large, there is a problem that the quality of the waveform compressed or expanded in the time axis direction is reduced.

[0004] In view of the above circumstances, it is an object of the present invention to provide a waveform compression / expansion apparatus in which the quality of a waveform compressed or expanded in the time axis direction is improved.

[0005]

According to the present invention, there is provided a waveform compressing / decompressing apparatus comprising: (1) waveform storing means for storing a plurality of waveforms having different playing speeds; A companding rate acquisition means for acquiring a companding rate to be compressed or expanded (3) One of a plurality of waveforms stored in the waveform storage means based on the companding rate acquired by the companding rate acquiring means.
And a compression / expansion means for selecting one of the waveforms and compressing / expanding the selected waveform in the time axis direction so as to obtain a waveform having a performance speed corresponding to the acquired compression / expansion rate.

Here, the waveform storage means further stores speed information indicating the performance speed of the waveform in correspondence with each of the plurality of waveforms, and the compression / expansion means stores the selected waveform in the waveform corresponding to the waveform. It is preferable to compress or expand in the time axis direction based on the ratio between the speed information and the companding rate acquired by the companding rate acquiring means.

The waveform compression / expansion apparatus of the present invention stores a plurality of waveforms having different playing speeds, and selects a playing speed corresponding to a companding rate close to the acquired companding rate from the plurality of waveforms. Because it selects a waveform and compresses or expands based on that waveform, it compares with the conventional technique of compressing or expanding one original waveform in the time axis direction.
The degree for compressing or expanding the waveform in the time axis direction is small. Therefore, the quality of the waveform compressed or expanded in the time axis direction can be improved.

[0008]

Embodiments of the present invention will be described below.

FIG. 1 is a block diagram showing a circuit configuration of a waveform compression / expansion apparatus according to a first embodiment of the present invention.

The waveform compression / expansion apparatus 100 shown in FIG.
ROM 11, RAM 12, CPU 13, display 1
4, an operator group 15, and a D / A converter 16. These ROM 11, RAM 12, CPU 1
3, display 14, operator group 15, D / A converter 16
Are connected to each other by a bus 17.

The ROM 11 is an example of the waveform storage means according to the present invention. The ROM 11 stores a plurality of waveforms having the same performance content but different performance speeds.
Details of the plurality of waveforms will be described later. Also,
The ROM 11 stores a waveform compression / decompression device 10 shown in FIG.
A program for controlling the entirety of the program, a program for compressing or expanding a waveform representing a musical tone in the time axis direction, and the like are stored.

The RAM 12 temporarily stores data and the like necessary for executing the above-mentioned programs and the like.

The CPU 13 performs processing for compression or decompression and other necessary processing based on a program or the like stored in the ROM 11.

The display 14 displays a companding rate for compressing or expanding the waveform in the time axis direction.

As will be described later in detail, the operator group 15 has a plurality of switches, and by operating these switches, the companding ratio is obtained and the waveform is reproduced.

The D / A converter 16 has a built-in buffer memory for temporarily storing waveform data representing a waveform, and stores the waveform data processed on the basis of the obtained companding ratio in the buffer memory. Then, waveform data is sequentially taken out from the buffer memory, D / A converted, and an analog signal is output. The output analog signal is
The sound is input to a sound source (not shown) and emitted into the air.

FIG. 2 is a view showing a panel on which the display and the operation group shown in FIG. 1 are arranged.

The panel 20 shown in FIG. 2 is provided with a display 14 and a group of controls 15. The display 14 shown in FIG. 2 displays 400% as an example of the companding ratio EXST. The operator group 15 includes a companding rate decreasing switch 151, a compensating rate increasing switch 152, and a reproduction start switch 153.

The companding rate decreasing switch 151 and the compensating rate increasing switch 152 are examples of the companding rate acquisition means according to the present invention. The companding rate decrease switch 151 is a switch for decreasing the companding rate EXST, and is a companding rate increasing switch 1.
Reference numeral 52 is a switch for increasing the companding rate EXST. The user operates the companding rate reduction switch 151 and the companding rate increasing switch 152 to obtain a desired companding rate EXST.
Set. Thereby, the compression / expansion rate EXST is acquired by the waveform compression / expansion apparatus 100.

The reproduction start switch 153 is a switch for reproducing a waveform.

Table 1 is a table for selecting a plurality of waveforms stored in the ROM 11.

[0022]

[Table 1]

The right column of this table shows the start addresses of five types of waveforms. The five types of waveforms designated by these head addresses are stored in the ROM 11. All five waveforms have the same performance content, and the performance speed ratio PES400 shown in the center row of this table is shown.
It is a waveform generated based on%, 200%, 100%, 50%, and 25%. The waveform generated based on the performance speed ratio PES 100% is a so-called equal-size original waveform generated by performing at a normal performance speed.
Also, the waveforms generated based on the performance speed ratios PES 400% and 200% are each 1% of the normal performance speed.
This is a waveform generated by performing at a low performance speed of ４ times and 倍 times, and is an original waveform corresponding to a waveform obtained by expanding a 1 × original waveform by 4 times and 2 times. Similarly, the performance speed ratio PES 50%, 25%
The waveforms generated on the basis of the above are waveforms generated by performing at a performance speed that is twice or four times the normal performance speed, respectively.
This is an original waveform corresponding to a waveform compressed to / 4.

In the left column of the table, these 5
Five types of companding ratio ranges (ES_m
in or more and less than ES_max). In the waveform compression / expansion apparatus 100 of the present embodiment, the expansion / compression ratio EXST in the range of the minimum compression / extension ratio 18.75% or more to the maximum expansion / compression ratio EXST of less than 601% in these five ranges of the expansion / compression ratio is set. Can be set.

The operation of the waveform compression / expansion apparatus 100 of this embodiment will be described below with reference to this table.

In the waveform compression / expansion apparatus 100, the acquired companding rate EXST is used as the companding rate EXST shown in this table.
If it is in the range of 300% or more to less than the companding ratio EXST 601%, a waveform with a performance speed ratio of PES 400% is selected, and the selected waveform is displayed as (compressing and extending ratio EXST / 4).
By compressing or expanding at the companding ratio of (00), a waveform expanded from the original waveform of the same size is obtained as a result. In addition, the drawing / extension ratio EXST is 150%.
If the drawing / expansion ratio EXST is within the range of less than 300%, a waveform with a performance speed ratio of PES 200% is selected, and the selected waveform is compressed or expanded at a drawing / expansion ratio of (compression / extension ratio EXST / 200). As a result, a waveform expanded from the original waveform of the same size is obtained. EXS
T is at least 75% draw ratio EXST 150% draw ratio EXST 150
%, The performance speed ratio PES10
A waveform of 0% is selected, and compression or expansion is performed based on the selected waveform. Furthermore, the companding ratio EXST is
If the drawing / expanding ratio EXST is within the range of 37.5% or more and the drawing / extending ratio EXST less than 75%, a waveform with a performance speed ratio of PES 50% is selected, and the selected waveform is displayed as (compression / extension ratio EXST
By compressing or expanding at a companding rate of (/ 50), a waveform compressed from an original waveform of the same size is obtained as a result. Draw ratio EXST 18.75% or more Draw ratio EXST3
If it is less than 7.5%, the performance speed ratio PE
The waveform of S25% is selected, and the selected waveform is compressed or expanded at a compression / expansion ratio of (compression / expansion ratio EXST / 25), thereby obtaining a compressed waveform from the original waveform of the same size.

More specifically, for example, the obtained drawing / expanding rate EXS
When T is 250%, the elongation ratio EXST 250% is
Since the drawing / expanding ratio EXST is in the range of 150% or more and the drawing / extending ratio EXST less than 300%, a waveform with a performance speed ratio of PES 200% is selected, and the waveform is drawn to an expansion ratio of 125% (250/2).
00). Also, for example, the acquired companding rate EX
When ST is 160%, this drawing and stretching ratio EXST 160%
Is in the range of 150% or more of the expansion / compression ratio EXST and less than 300% of the expansion / compression ratio, as in the previous example.
Stretch at 0% (160/200). Further, for example,
When the obtained drawing and stretching ratio EXST is 40%, the drawing and drawing ratio E
Since the XST 40% is in the range of the compression / extension ratio EXST 37.5% or more and the compression / extension ratio EXST 75% or less, the waveform of the performance speed ratio PES 50% is selected, and the compression ratio is 80%.
Compress by (40/50). Therefore, when compressing or decompressing a waveform, the degree of decompression or compression can be reduced compared to the conventional technique of preparing only one original waveform for one performance content and compressing or decompressing the original waveform. The quality of the waveform compressed or expanded in the time axis direction can be improved.

As described above, the waveform compression / expansion apparatus 100 of the present embodiment provides the performance speed ratio PES for the same performance content.
Five kinds of waveforms of 400%, 200%, 100%, 50%, and 25% are stored in the ROM 11, and when the minimum companding rate EXST of 18.75% is acquired, the waveform of the performance speed ratio PES25% is obtained. Select and compress 75% (18.7)
5/25), and when a maximum companding rate EXST of 600% was obtained, a waveform with a performance speed ratio of PES 400% was selected and expanded at a rate of 150% (600/400). Since the compression or expansion is performed by selecting the waveform of the performance speed ratio PES that is closest to the expansion / compression ratio EXST, the time axis extends over a wide range from the expansion / compression ratio of 18.75% or more to the expansion / compression ratio of less than 601%. The quality of the waveform compressed or expanded in the direction can be improved.

FIG. 3 is a flowchart of a routine executed when the companding rate decreasing switch or compensating rate increasing switch shown in FIG. 2 is pressed.

When the companding rate decrease switch 151 or the companding rate increasing switch 152 is pressed, this routine starts.

First, in step S11, when the companding rate decrease switch 151 is pressed, the companding rate EXST is decreased, and when the companding rate increasing switch 152 is pressed, the companding rate EXST is increased. Next, in step S12, the companding rate EXST is displayed on the display 14, and this routine is terminated. The user presses the companding rate decrease switch 151 or the companding rate increasing switch 152, and looks at the companding rate EXST displayed on the display 14 to obtain the desired companding rate EXST
Set. Thus, the waveform compression / expansion device 100
Then, the companding ratio EXST is obtained.

FIG. 4 is a flowchart of a routine executed when the reproduction start switch shown in FIG. 2 is pressed.

When the reproduction start switch 153 shown in FIG. 2 is pressed by the user, this routine is started, and in step S21, a compression / expansion processing routine is executed based on the obtained compression / expansion ratio EXST. This compression / decompression processing routine will be described with reference to the flowchart shown in FIG.

FIG. 5 is a flowchart of the compression / decompression processing routine.

First, in step S211, a pointer is set at the head of the table described above. Next, in step S212, the obtained companding ratio EXST is set to the value indicated by ES_min ≦ EXST <ES_
max, that is, when the obtained drawing and stretching ratio EXST is 3
It is determined whether it is within the range of 00% or more and less than 601%. If it is determined that the drawing / extending ratio EXST is within the range of 300% or more and less than 601%, the process proceeds to step S213. In step S213, the 300%
Performance speed ratio PES corresponding to the range of not less than 601%
By selecting a 400% waveform, the waveform to be used is determined, and the process proceeds to step S214. In step S214, the waveform is reproduced by performing expansion based on the determined waveform (the waveform generated at the performance speed corresponding to the performance speed ratio PES 400%), the musical sound is emitted, and this routine ends.

On the other hand, if it is determined in step S212 that the obtained drawing / expansion rate EXST is out of the range of 300% or more and less than 601%, the process proceeds to step S215.
In step S215, the pointer is sent to the next row in the table, and the process returns to step S212. Similarly, in step S212, the acquired companding rate EXST is
The range of the companding rate EXST indicated by the pointer (E
(S_min or more and less than ES_max) is determined, and if it is determined to be included, step S21 is performed.
In step 3, the waveform to be used is determined, and if it is determined that the waveform is not included, step S215 is executed to execute step S21.
2 is repeated, and finally step S2
At 13, the waveform to be used is determined.

[0037]

As described above, according to the present invention,
The quality of the waveform compressed or expanded in the time axis direction can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a circuit configuration of a waveform compression / decompression device according to an embodiment of the present invention.

FIG. 2 is a view showing a panel on which the display and the operation group shown in FIG. 1 are arranged.

FIG. 3 is a flowchart of a routine executed when a companding rate decreasing switch or a compensating rate increasing switch shown in FIG. 2 is pressed.

FIG. 4 is a flowchart of a routine that is executed when a reproduction start switch shown in FIG. 2 is pressed.

FIG. 5 is a flowchart of a compression / decompression processing routine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ROM 12 RAM 13 CPU 14 Display 15 Operator group 16 D / A converter 17 Bus 20 Panel 100 Waveform compression / expansion device 151 Companding rate decreasing switch 152 Companding rate increasing switch 153 Playback start switch

Claims (2)

[Claims] 1. A waveform storing means for storing a plurality of waveforms having different playing speeds; a companding rate acquiring means for acquiring a companding rate for compressing or expanding a waveform in a time axis direction; Means for selecting one waveform from the plurality of waveforms stored in the waveform storage means based on the companding rate acquired by the means, and selecting the selected waveform with a playing speed corresponding to the acquired companding rate. A waveform compression / expansion device comprising compression / expansion means for compressing / expanding in the time axis direction so as to obtain a waveform. 2. The waveform storage means further stores speed information representing a performance speed of a waveform corresponding to each of a plurality of waveforms, and the compression / expansion means stores the selected waveform in the speed corresponding to the waveform. 2. The waveform compression / expansion apparatus according to claim 1, wherein the compression / expansion is performed in the time axis direction based on a ratio between information and the compression / expansion rate acquired by the compression / expansion rate acquisition unit.