JPH01137299A - Voice time base compression system - Google Patents

Abstract

PURPOSE: To compress time base so that the frequency change cannot be sensed by detecting the level difference of sound data and discriminating whether it is zero or not by comparison to perform the extraction control of data. CONSTITUTION: Conversion data (m) of sound (a) is inputted to a detector 4 from a memory 1 as data (e), and level difference detection data (f) is inputted to a comparator 5 and is compared with zero to send data (g) to an extraction controller 8. A control signal (h) is sent to a counter 3 and the controller 8 from a counter 2. The counter 3 outputs a control signal (i) for each count of the number of groups, and an adder 7 adds and sets data (d) of a counter 6 and compression rate data (c) by the signal (i). In accordance with a control signal (j) indicating whether the counter value is zero or not, a signal (h), and data (g), the controller 8 sends a data extraction control signal (k) to an extractor 9 not to input sound data from the memory 1 to a memory 10. Data processed by the extractor 9 is stored in the memory 10 and becomes compressed analog sound (n) after completion of sound data storage. Thus, the time base is compressed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a time-base compression method for audio, and more particularly to a time-base compression method for keeping frequency changes in audio due to time-base compression within a range that cannot be audibly detected.

[Conventional technology]

Conventionally, in this type of audio time axis compression method, audio is first recorded on an audio recording/playback device using magnetic tape,
This was done by increasing the rotation speed of the capstan during playback. In the digital system, the time axis is compressed by increasing the sampling frequency during playback compared to when recording. [Problems to be solved by the invention] A system using a conventional recording/playback device using magnetic tape, etc. and a digital system. In the method of digitally recording the digital data and playing it back at a sampling frequency faster than the recording time,
This had the disadvantage that the frequency during playback became high and the fidelity to the original sound deteriorated.

[Means for solving problems]

The audio time axis compression method of the present invention includes: an A/D converter that converts analog audio into digital audio data; a plurality of first data storage memories that store the converted digital audio data for each group; a group counter that determines the number of data; a block counter that determines the number of blocks of a plurality of groups; and a detection that detects a level difference between the front and rear data in each group of the first data storage memory. a plurality of comparators for comparing whether the result data from the detector is zero; and a plurality of comparators for adding the compression rate data given the value of the extraction counter for each block by the control signal of the block counter. an adder, an extraction counter that sets and counts down the addition result for each addition, and extraction control that determines whether or not audio data is extracted from the values of the group counter and the extraction counter and the comparison result data from the comparator. an extraction controller that reads data from the first data storage memory and extracts the data under control from the extraction controller; and a first data storage memory that stores the audio digital data processed by the extraction controller. The second data storage memory includes a second data storage memory, and a D/A converter that converts audio digital data read from the second data storage memory using a reproduction clock into analog data.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram of one embodiment of the present invention. In the embodiment of the present invention shown in this figure, an A/D converter 11 converts analog audio a into digital audio, and N storage memories 1 store A/D-converted digital audio data m.
(11 to IN), a group counter 2 that determines the number of data to be stored in each storage memory, and a block counter 3 that determines the number of groups in one block to collect M groups to form one block. N-1 level difference detectors 4 for detecting level bases before and after N memories 1
and the result data f of the detector 4.

That is, a comparator 5 that compares whether the level difference is zero, and an extraction counter 6 that counts how many pieces of audio data are extracted based on the given compression ratio data C.
An adder 7 adds the data d of the counter 6 and the pressure linearity data C for each block, and the control signal of the counter 2, the control signal j of the counter 6, and the result data g of the comparator 5 are used to determine whether or not to extract data. an extractor 9 that reads data from the storage memory 1 and actually extracts the audio data according to a control signal k from the controller 8; It is comprised of a memory 10 that automatically stores audio data every time it is recorded, and an A/D converter 12 that reads audio data from the memory 10 after storing it and converts it into analog audio.

The analog audio a is converted into digital audio data by the A/D converter 11, and the converted data m is sequentially stored in the data storage memory 1, and the counter 2 counts the number of data.

A level difference in the audio data e stored in the storage memory 1 is detected by a detector 4 that detects a level difference between data before and after the data. The detected data f is input to the comparator 5, and a comparison is made to see if the data f is zero.The result is extracted and the comparator result data g is sent to the controller 8. Simultaneously with the above operation, the counter 2 sends a control signal to the counter 3 and the extraction controller 8 for each number of data corresponding to one group. The counter 3 increases the number of counters in response to a control signal, and outputs a control signal i every time the number of groups corresponding to one program is counted. Based on this control signal i, the adder 7 adds the data d of the counter 6 and the compression ratio data C.
The result is newly added to the counter 6. Counter 6 receives a control signal j indicating whether the counter value is zero or not.
is sent to the controller 8. The controller 8 outputs the data extracting control signal k based on the aforementioned control signal j and the comparator result data g, and the extractor 9 does not input the audio data from the memory 1 to the memory 10 based on the control signal k. Since no data is input to the memory 10, the memory 10 does not store data in the memory and waits for the next data to be input.
The state is the same as if the data had been extracted. When data is extracted, the counter 6 counts down in response to the signal 1 from the extractor 9 and manages the number of extracted data.

The data processed by the extractor 9 is temporarily stored in the memory 10.
After the audio data has been stored, it is read out by the reproduction clock and converted into a real analog signal by the D/A converter 12, resulting in compressed analog audio n.

FIG. 2 is a conceptual diagram showing how data is compressed. The comparison result in the comparator 5 is a @ + of the input audio data.
If there is no sound at H, or if the difference from the signal (aI,) one clock previous is "0" or less than a predetermined value, a pull signal k is generated. While this extraction signal is being generated, WRITE to the memory 10 is not executed.
signal and the counter control signal of the address counter are not input. Therefore, data afi is normally stored at memory address n, and data afi is stored at address n+1.
Aa+z is stored instead of n+l, and then data afi+3 is stored normally at address n+2. Compression processing is realized by reading out the data stored in this manner in address order using a reproduced clock.

〔Effect of the invention〕

As explained above, the present invention detects the level difference before and after digital audio data and compares whether or not the detected data is zero in order to prevent discomfort caused by data extraction processing. Controls data extraction. In addition, since the number of data to be extracted for each group is limited, it is possible to prevent two or more pieces of data from being extracted consecutively within one block. can be kept very close to. Therefore, it is possible to compress the time axis so that changes in the frequency of the audio are not perceptible to the auditory sense.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the audio time axis compression method of the present invention, and FIG. 2 is a conceptual diagram showing how data is compressed. 11~IN...Digital audio data storage memory, 2
...Group counter, 3...Block counter. 41-4N...Level difference detector, 5...Comparator, 6
... Extracting counter, 7... Adder, 8... Extracting controller, 9... Extracting device, 10... Storage memory, 11... A/D converter, 12... D /A converter, a...analog audio, C...compression rate data, d
... Extraction counter data, el~eN... Digital audio data, f, ~rs-,... Level difference comparison data, g... Comparator result data, h... Block counter control signal, l ...Adder control signal, j...
Pull-out counter control signal, k... Puller control signal, l! ... Extraction result signal, m... Digital audio data, n... Compressed audio signal.

Claims (1)

[Claims] an A/D converter that converts analog audio data to digital audio data; a plurality of first data storage memories that collect a certain number of samples of the converted digital audio data and store them for each group; a block counter for determining the number of groups of blocks consisting of a plurality of groups; a detector for detecting a level difference before and after the data in each group of the first data storage memory; a plurality of comparators that compare whether the result data from the block counter is zero; an adder that adds the value of the extraction counter and the given compression ratio data for each block according to the control signal of the block counter; an extraction counter that sets and counts down a result for each addition; an extraction controller that performs extraction control by determining whether or not audio data is extracted based on the values of the group counter and the extraction counter and comparison result data from the comparator; , an extractor that reads data from the first data storage memory and extracts the data under control from the extractor controller; and a second data storage memory that stores the audio digital data processed by the extractor. , said second
A D/D converter that converts audio digital data read from the data storage memory using a reproduction clock into analog audio.
An audio time axis compression method characterized by being configured with an A converter.