JP2000243065A - Audio data processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an audio data processor in which unpleasant sounds caused by discontinuous points of audio data are reduced and tone quality in hearing sensation is improved. SOLUTION: If a discontinuous point detecting circuit 1 detects a discontinuous point included in inputted audio data, a hold circuit 2 holds the last data immediately before the point. A fade out circuit 3 fades out the last data, a fade in circuit 4 fades in the data, which are inputted after the discontinuous point, and these data are added by an adding circuit 5 and outputted as audio data. Preferably, a switching circuit 7 outputs the added data during the fade adding processing, and outputs the data delayed by a delaying circuit 6 during other period while considering an adding process time. Thus, the leading point of the data inputted after the discontinuous point is connected to the last data to produce continuous data and unpleasant sounds are reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an audio data processing apparatus, and more particularly to an audio data processing apparatus that performs processing to reduce unpleasant sounds due to discontinuities in audio data.

[0002]

2. Description of the Related Art In an audio data editing apparatus, data in a certain section may be cut out and connected to data in another section. At this time, an audio point is edited at an editing point, that is, at a data connection part. The difference may cause a discontinuity point. If the audio data is reproduced in a state where such a discontinuous point exists, the discontinuous point becomes noise, and the sound is heard as a very unpleasant sound. In order to avoid this, conventionally, processing is performed so that a portion where a discontinuous point is formed is processed so as not to be discontinuous. Two examples are shown below.

FIG. 7 is a diagram for explaining a method for avoiding discontinuous points by crossfading. In this figure, it is assumed that subsequent data D2 is input following the previous data D1 as an input signal. At this time, a joint between the data D1 and the data D2 is a discontinuous point. In order to suppress the occurrence of noise at the discontinuous point, the audio level of the data D1 is not instantaneously reduced to 0% at the discontinuous point, but is reduced stepwise from 100% to 0%, and the data D2 is reduced. A crossfade is performed in which the audio level is not increased to 100% instantaneously but is increased stepwise from 0% to 100%. With this crossfade,
The output signal has no discontinuity, and the generation of noise is suppressed.

FIG. 8 is a diagram for explaining a method for avoiding discontinuous points by fade-out and fade-in. Also in this figure, it is assumed that the subsequent data D2 is input following the previous data D1 as an input signal. In this example, first, near the end of the data D1, fade-out is performed to gradually reduce the audio level of the data D1 from 100% to 0% at a discontinuous point with the data D2. Performs a fade-in in which the audio level of the data D2 is gradually increased from 0% to 100%. This fade-out and fade-in eliminates discontinuities in the output signal and eliminates noise.

[0005]

However, in the method using the cross-fade, it is necessary that the previous data continue to exist after the discontinuity point, and this method is applied when two data are switched by a switch. If the data to be cross-fade has a discontinuity point, the data cannot be post-processed. In the fade-out / fade-in method, data processing must be started before the discontinuity point. Therefore, the position of the discontinuity point must be known in advance, and a circuit for delaying audio data by that amount is required. Is required. In addition, since the processing section is located before and after the discontinuity point, there is a problem that, in some cases, the sound is muted for a moment and can be heard.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and reduces the unpleasant sound due to reproduction of data having discontinuous points generated as a result of editing audio data, thereby improving the audible sound quality. An object of the present invention is to provide an audio data processing device that is improved.

[0007]

According to the present invention, an audio data processing apparatus for processing audio data having a discontinuity point detects a discontinuity point of input audio data and generates a fade section signal for a predetermined time. Output discontinuity point detection means, holding means for holding final data immediately before the discontinuity point in response to the fade section signal, and the last data held by the hold means in response to the fade section signal A fade-out means for fading out data, a fade-in means for fading in audio data inputted after the discontinuity point in response to the fade section signal, and adding data outputted from the fade-out means and the fade-in means. Audio data processing comprising: Apparatus is provided.

According to the above arrangement, the discontinuous point detecting means monitors the input audio data and detects the discontinuous point contained therein. When a discontinuity point is detected, the holding means holds the last data immediately before the discontinuity point, and the fade-out means fades out the last data,
The fade-in means fades-in the data after the discontinuity point, and the addition means adds the data to output audio data. As a result, since the data input after the discontinuity point is continuous data with the head connected to the final data, unpleasant sounds are reduced, and the sound quality in audibility is improved.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an audio data processing device according to the present invention. As shown in the figure, the audio data processing device monitors a received audio data and detects a discontinuous point included therein, and the input audio data and the discontinuous point detection circuit 1 , A fade-out circuit 3 for inputting the output of the hold circuit 2 and the output of the discontinuity point detection circuit 1, and inputting the input audio data and the output of the discontinuity point detection circuit 1 A fade-in circuit 4, a fade-out circuit 3, and an adder circuit 5 for receiving the outputs of the fade-in circuit 4, a delay circuit 6 for receiving the input audio data, an adder circuit 5, a delay circuit 6, and a discontinuous point detection. And a switching circuit 7 for receiving the output of the circuit 1.

In this audio data processing apparatus, audio data to be processed can be applied in either analog or digital form, and each component is configured according to the form.

The discontinuous point detecting circuit 1 detects a discontinuous point from input audio data and outputs a fade section signal for a predetermined time from the detection, and can be constituted by, for example, a differentiating circuit and a timer circuit. The hold circuit 2 sequentially samples input continuous audio data, and receives the fade section signal from the discontinuity point detection circuit 1 to hold the last data sampled immediately before the discontinuity point. The fade-out circuit 3 receives the fade section signal from the discontinuous point detection circuit 1 and reduces the audio level of the data held in the hold circuit 2 by 100% during a predetermined time during which the fade section signal is received. From 0%
Fade-out is performed stepwise or continuously. The fade-in circuit 4 receives the fade section signal from the discontinuity point detection circuit 1 and outputs audio data input after the discontinuity point during a predetermined time during which the fade section signal is received. Perform a fade-in that gradually or continuously increases the level from 0% to 100%. The adder circuit 5 adds the data in which the final value of the data before the discontinuity point is faded out by the fade-out circuit 3 and the data in which the data after the discontinuity point is faded in by the fade-in circuit 4.
The delay circuit 6 delays the audio data by the time of the fade addition processing by the fade-out circuit 3, the fade-in circuit 4, and the adder circuit 5. The switching circuit 7 normally switches the input to the output side of the delay circuit 6 so that the delayed audio data is output as audio data, and the discontinuous point detecting circuit 1 detects the discontinuous point and outputs the fade section signal. During the predetermined time during which the audio signal is output, the input is switched to the output side of the adder circuit 5, and the audio data subjected to the fade addition processing is output.

Next, the audio data processing operation of the audio data processing device will be described in more detail. FIG. 2 is a diagram for explaining a processing ratio for audio data, and FIG. 3 is an explanatory diagram showing an example of a change in analog output. The input signal includes the first half signal and the second half signal,
It is assumed that there is a step in the audio level, that is, a discontinuity point, at those connection portions as shown in FIG. First, when the first half signal is input as audio data input, the discontinuous point detection circuit 1 outputs a fade section signal “L” to its output. At this time, the switching circuit 7
Has its input switched to the output side of the delay circuit 6, and the data delayed by the delay circuit 6 is output as it is as an audio data output. Therefore, the input first-half signal is output without any processing other than the delay as shown in FIG.

Next, when a discontinuous point is detected by the discontinuous point detecting circuit 1, the discontinuous point detecting circuit 1 outputs a fade section signal "H" to its output. In response to the fade section signal "H", first, the hold circuit 2 holds the final data of the first half signal and continues to output the final hold value. Upon receiving the fade section signal “H”, the fade-out circuit 3 performs fade-out with respect to the final hold value output from the hold circuit 2. As a result, the final hold value is reduced stepwise or continuously from 100% to 0%. On the other hand, the fade-in circuit 4
Receives the fade section signal "H", fades in the latter half signal after the discontinuity point, and increases the leading portion of the latter half signal stepwise or continuously from 0% to 100%. Next, the final hold value of the faded-out first half signal and the faded-in second half signal are added by the adding circuit 5. Immediately after the discontinuity point, the output of the fade-out circuit 3 has the final hold value, and the output of the fade-in circuit 4 has an audio level of 0, so that the output of the adder circuit 5 indicates the final hold value. Therefore, at the discontinuity point, the second half signal has a waveform that is continuous with the first half signal. At this time, since the switching circuit 7 switches the input to the output side of the adding circuit 5 in response to the fade section signal “H”, the added output signal is output as the audio data output.

When the fade section signal becomes "L", the final hold value becomes 0% and the latter half signal becomes 100%. Thereafter, the switching circuit 7 switches the input to the side of the delay circuit 6, and outputs the delayed second half signal as it is.

In the above embodiment, the output signal from the adder circuit 5 is used as the audio data output only while the discontinuous point detecting circuit 1 detects the discontinuous point and outputs the fade section signal "H". However, when the deterioration of the data due to the processing by the fade-out circuit 3, the fade-in circuit 4, and the addition circuit 5 can be substantially ignored, the output signal of the addition circuit 5 is always output as audio data. It can also be configured as follows. That is, the audio data processing device can have a configuration in which the delay circuit 6 and the switching circuit 7 are omitted. This makes it possible to realize an inexpensive audio data processing device having a simple configuration.

Next, an application example of an audio data processing apparatus capable of processing discontinuous points into continuous data will be described. FIG. 4 is an explanatory diagram showing an example of application to an audio editing device. The audio editing device may be any of linear editing using a tape medium, for example, non-linear editing using a magnetic disk medium. 2. Description of the Related Art In an audio editing apparatus, it is frequently performed to insert another audio data into a certain audio data and to assemble into a continuous audio data. In such a case, as shown before processing in the figure, the IN point and the OUT point, which are the editing points of the inserted audio data, are discontinuous points.

By applying the audio data processing device of FIG. 1 to such discontinuous points, as shown in FIG. 4 after processing, the data at the discontinuous points becomes pseudo continuous data. It is converted, and the unpleasant sound can be reduced.

FIG. 5 is an explanatory diagram showing an example of application to an interpolation processing circuit for missing data during variable speed reproduction. For example, some digital recording type video tape recorders have a function that allows variable speed playback of audio. When performing variable-speed playback of audio using this variable-speed playback function,
Data loss may occur. Interpolation processing is usually performed for such missing data. In the interpolation processing, as shown in the figure, continuous data is obtained by reusing data immediately before the occurrence of an error as interpolation data, but discontinuous points occur at the front and rear ends of the interpolation data.

By applying the audio data processing device shown in FIG. 1 to such discontinuous points, the data at the discontinuous points by the interpolation processing performed for the missing data at the time of variable-speed reproduction can be converted to continuous data. And the reproduced sound of the interpolation data can be made closer to a more natural timbre.

FIG. 6 is an explanatory diagram showing an example of application to audio data deleted during a high-speed search. For example, some digital recording type video tape recorders have a function capable of reproducing audio even during high-speed search processing. The audio data at the time of the high-speed search is thinned out in length according to the speed. For example, in the case of a 2 × speed search, as shown in the figure, half of the data is deleted, and the remaining data is joined to form audio data to be reproduced. In such a case, a discontinuous point occurs at the joining portion.

By applying the audio data processing device of FIG. 1 to such discontinuities, the search sound can be made closer to analog sound quality.

[0022]

As described above, according to the present invention, when a discontinuous point is included in the input audio data, the last data immediately before the discontinuous point is held, and after the discontinuous point is detected. The data at the discontinuous point is converted into a continuous point by fading out the last hold data, fading in the data inputted after the discontinuous point, adding them, and outputting the result. As a result, even if a discontinuity point is generated by performing editing, variable-speed reproduction, search, or the like, the discontinuity point is set as a continuous point, so that reproduction noise due to the discontinuity point is reduced, and the sound quality in audibility is improved. be able to.

Further, since the audio data processing device according to the present invention is applied to reproduction output of audio data, original data can be stored without any processing.

In the present invention, the processing section can be halved as compared with the conventional fade-in / fade-out method, so that the mute is reduced in audibility and the audibility is reduced. Therefore, it is easy to match the processing timing, and there is no need to predict discontinuous points in advance.

Further, according to the present invention, all analog and digital audio data having discontinuities, for example, edit points in audio editing, video tape recorders, compact discs, DVDs (Digital Vers.
audio data that includes error data missing due to variable-speed playback (atile Disk), joints when skipping data such as search sounds are joined, and switching between audio signals switched by a switcher, etc. Also, the sound quality can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an audio data processing device according to the present invention.

FIG. 2 is a diagram illustrating a processing ratio for audio data.

FIG. 3 is an explanatory diagram showing a change example of an analog output.

FIG. 4 is an explanatory diagram showing an example of application to an audio editing device.

FIG. 5 is an explanatory diagram showing an example of application to an interpolation processing circuit for missing data during variable speed reproduction.

FIG. 6 is an explanatory diagram showing an example of application to audio data deleted during a high-speed search.

FIG. 7 is a diagram illustrating a method for avoiding discontinuous points by crossfading.

FIG. 8 is a diagram illustrating a method for avoiding discontinuous points by fading out and fading in;

[Explanation of symbols]

1... Discontinuity point detection circuit, 2... Hold circuit, 3.
Fade-out circuit, 4 ... Fade-in circuit, 5 ...
Addition circuit, 6 delay circuit, 7 switching circuit.

Claims (5)

[Claims] 1. An audio data processing device for processing audio data having a discontinuity point, comprising: a discontinuity point detecting means for detecting a discontinuity point of input audio data and outputting a fade section signal for a predetermined time; Holding means for holding last data immediately before the discontinuity point in response to a fade section signal; fade-out means for fading out the last data held in the hold means in response to the fade section signal; Fade-in means for fading in audio data input after the discontinuity in response to the section signal; andaddition means for adding data output from the fade-out means and fade-in means. An audio data processing device characterized by the above-mentioned. A delay means for delaying the input audio data by the predetermined time; and a switch for switching an input from the output of the delay means to the output of the addition means for the predetermined time in response to the fade section signal. 2. The audio data processing device according to claim 1, further comprising: means. 3. The audio data processing device according to claim 1, wherein said audio data is an analog or digital signal edited by an audio editing device. 4. The audio data processing device according to claim 1, wherein the audio data is a signal obtained by interpolating missing data due to variable speed reproduction of the audio reproduction device. 5. The audio data processing device according to claim 1, wherein the audio data is a signal obtained by joining skipped data by variable-speed reproduction of an audio reproduction device.