JP2004266724A - Real time voice buffer control apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a real time voice buffer control apparatus capable of reproducing voice without a sense of incongruity even on the occurrence of transmission fluctuations in a network. <P>SOLUTION: A reception buffer monitor means 113 monitors a consumed capacity of a reception buffer means 112 and informs a voice waveform data processing correction means 114 about it when the consumed capacity is lower than a preset lower limit capacity or exceeds a prescribed upper limit capacity. When the consumed capacity of the reception buffer means 112 is lower than the lower limit, the voice waveform data processing correction means 114 processes and corrects the waveform of voice data outputted from the reception buffer means 112 to increase the data amount and to extend the reproduction time, and when the consumed capacity of the reception buffer means 112 exceeds the upper limit, the voice waveform data processing correction means 114 processes and corrects the waveform of voice data outputted from the reception buffer means 112 to decrease the data amount and to reduce the reproduction time thereby eliminating a sense of incongruity from the reproduced voice. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a system for performing real-time voice communication via a network that provides a packet transfer service, and relates to a real-time voice buffer control device that controls a buffer on the receiving side.
[0002]
[Prior art]
Conventionally, when real-time voice communication is performed via a packet transfer network, voice data exceeding the buffer capacity is lost if there is data transfer exceeding the buffer capacity on the receiving side due to data transmission fluctuation (jitter) on the network. In addition, when the delay in the network increases, the audio data is interrupted.
[0003]
To reduce the loss of audio data exceeding the buffer capacity due to such jitter, a real-time audio buffer control device has been proposed.
[0004]
As shown in FIG. 11, the real-time audio buffer control device 200 includes a reception buffer 201, a reproduction control module 202, a switcher 203, a high-speed reproduction module 204, and an audio decoder 205.
[0005]
The real-time audio buffer control device 200 converts the received packet into audio data and outputs the audio data to the audio reproduction module 300. The reproduction control module 202 monitors the data accumulation amount of the reception buffer 201, and the data accumulation amount becomes the second. When the threshold value exceeds 1, the output of the reception buffer 201 is switched to the high-speed reproduction module 204 by the switcher 203, and the high-speed reproduction module 204 performs packet thinning to process data at high speed, thereby reducing the amount of data stored in the reception buffer 201. When the data storage amount of the reception buffer 201 becomes smaller than the second threshold, the output of the reception buffer is switched to the audio decoder 205 by the switcher 203, and the normal reproduction speed is set (for example, , Patent Document 1).
[0006]
[Patent Document 1]
JP 2000-295286 A
[Problems to be solved by the invention]
However, in such a conventional real-time audio buffer control device, although it is possible to reduce the loss of audio data exceeding the buffer capacity, it is possible to cope with a case where audio data is interrupted due to a network transmission delay. Therefore, it is necessary to increase the buffer capacity, and the delay increases.
[0008]
If the buffer capacity is reduced in order to reduce the delay, as shown in FIG. 12, even after the reproduction of the audio data is completed, a state occurs in which the next audio data cannot be made in time due to jitter (a state in which the jitter cannot be absorbed). As shown in FIG. 13, the sound waveform is disturbed, and as a whole (as viewed in a macro) the sound waveform becomes discontinuous as compared with the original sound as shown in FIG. There is a problem.
[0009]
SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and an object of the present invention is to provide a real-time audio buffer control device capable of reproducing sound without any uncomfortable feeling even when network transmission fluctuations occur.
[0010]
[Means for Solving the Problems]
The real-time audio buffer control device of the present invention is a reception buffer unit for temporarily storing received audio data, and an upper limit and a lower limit are set in advance, and the usage amount of the reception buffer is set to the lower limit. The receiving buffer monitoring means for detecting and outputting that the amount has fallen or the usage amount of the reception buffer means has exceeded the upper limit, and the reception buffer monitoring means has determined that the usage amount of the reception buffer means has reached the lower limit. When the output of the reception buffer unit is output, the audio data output by the reception buffer unit is subjected to waveform processing correction to increase the data amount, and the reception buffer monitoring unit determines that the usage amount of the reception buffer unit exceeds the upper limit value. When audio data is output, the audio data output by the reception buffer means is subjected to waveform processing correction to reduce the data amount. It has a configuration and a correcting means.
[0011]
With this configuration, when the usage amount of the reception buffer means falls below the lower limit value, the data amount of the audio data is increased to avoid an underflow state, and when the usage amount of the reception buffer means exceeds the upper limit value, the audio data is reduced. To reduce the amount of data to avoid an overflow state.
[0012]
Here, if the received audio data is compressed audio data that has been subjected to data compression, a configuration is provided in which compressed audio decoding means is provided for decoding the compressed audio data, restoring the audio data, and outputting the restored audio data to the reception buffer means.
With this configuration, it is also possible to process audio data that has been compressed.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a configuration of a voice receiving device according to an embodiment of the present invention.
[0014]
As shown in FIG. 1, the audio receiving device 1 of the present embodiment reproduces audio data output from the real-time audio buffer control device 11 and a real-time audio buffer control device 11 that receives data from the network 2. Audio reproducing means 12 is provided.
[0015]
The real-time audio buffer control device 11 includes a packet receiving unit 111 that extracts and outputs audio data from packet data received from the network 2, and a reception buffer unit 112 that temporarily stores audio data output by the packet receiving unit 111. A reception buffer monitoring unit 113 for monitoring a buffer use state of the reception buffer unit 112; and an audio waveform data waveform processing correction unit 114 for waveform processing correction of audio waveform data based on the monitoring result of the reception buffer monitoring unit 113. ing.
[0016]
As shown in FIG. 2, such a voice receiving apparatus 1 can communicate with a voice transmitting apparatus 3 for transmitting real-time voice data to a network 2 via the network 2. The audio data is received via the network 2 and reproduced.
[0017]
When transmitting an audio having a waveform as shown in FIG. 3A, the audio transmitting device 3 divides the audio data into predetermined lengths as shown in FIG. The data is converted into packet data and transmitted to the voice receiving device 1 via the network 2.
[0018]
As shown in FIG. 4, the audio receiving device 1 buffers the audio data of the received packet, and sequentially reproduces the buffered audio data.
[0019]
As shown in FIG. 5, the reception buffer unit 112 continuously stores the audio data of the received packet, sequentially outputs the audio data to the audio waveform data waveform correction unit 114, and deletes the output audio data. It has become.
[0020]
It is preferable that a certain amount of data is always stored in the reception buffer unit 112. The arrival of a packet of audio data is delayed due to the jitter of the network 2 so that all the audio data stored in the reception buffer unit 112 is output. If this happens, there will be a state in which there is no audio data to be reproduced (underflow state).
[0021]
If the capacity of the reception buffer means 112 is increased to prevent this state, a delay occurs in the reproduction of the audio data, and the audio data to be received and stored exceeds the capacity of the reception buffer means 112 (overflow state). )Become.
[0022]
In the real-time audio buffer control device 11 of the audio reception device 1 according to the present embodiment, the reception buffer monitoring unit 113 monitors the use state (the amount of data stored) of the reception buffer unit 112, and detects an underflow state or overflow. The state immediately before the state is sensed and notified to the audio waveform data waveform processing / correction means 114, and the audio waveform data waveform processing / correction means 114 corrects the waveform of the audio data to adjust the usage of the reception buffer means 112. It has become.
[0023]
Specifically, the receiving buffer monitoring unit 113 sets a lower limit and an upper limit of the buffer usage in advance, and when the buffer usage of the receiving buffer unit 112 falls below the lower limit, or when the buffer usage becomes lower. When the value exceeds the upper limit value, the audio waveform data waveform processing correction means 114 is notified.
[0024]
When notified that the buffer usage of the reception buffer unit 112 has fallen below the lower limit, the audio waveform data waveform processing correction unit 114 performs waveform processing correction on the audio data input from the reception buffer unit 112, and FIG. As shown in the figure, the data amount is increased so that the playback time becomes longer, so that a packet delayed during playback of the increased audio data arrives.
[0025]
When notified that the buffer usage of the reception buffer unit 112 has exceeded the upper limit value, the audio waveform data waveform processing correction unit 114 performs waveform processing correction on the audio data input from the reception buffer unit 112, and As shown in FIG. 7, the data amount is reduced so that the reproduction time is shortened, the reproduction time of the audio data is shortened, and the data amount stored in the reception buffer means 112 is reduced quickly.
[0026]
The reproduced waveform of the audio data subjected to the waveform processing correction is as shown in FIG. 8, and when viewed macroscopically, as shown in FIG. 9, the waveform is continuous and has no delay.
[0027]
As described above, in the present embodiment, the buffer usage of the reception buffer unit 112 is monitored by the reception buffer monitoring unit 113, and if the buffer usage exceeds a preset upper limit value or exceeds a lower limit value, the audio waveform data waveform processing correction unit By notifying to 114 and adjusting the reproduction time of the audio data by performing waveform processing correction on the audio data by the audio waveform data waveform processing correction means 114, it is possible to reproduce a sound with no uncomfortable feeling and with a small delay.
[0028]
As another aspect of the present embodiment, as shown in FIG. 10, when the audio data output by the packet receiving unit 111 is audio data with a compressed data capacity, the compressed audio data is decoded. A real-time audio buffer control device 13 provided with a compressed audio decoding means 131 for returning the original data to output to the reception buffer means 112 is provided. With this configuration, even when the received audio data is compressed, it is possible to reproduce the audio with no uncomfortable feeling and with a small delay.
[0029]
【The invention's effect】
As described above, according to the present invention, the usage amount of the reception buffer means is monitored, and when an underflow state is likely to occur, the data amount of audio data is increased by waveform processing correction, and an overflow state is likely to occur. In such a case, by reducing the data amount of the audio data by the waveform processing correction, the underflow state and the overflow state can be avoided, and the audio can be reproduced without a sense of incongruity even if the network transmission fluctuation occurs.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a voice receiving apparatus according to an embodiment of the present invention; FIG. 2 is a configuration diagram illustrating a use form of the voice receiving apparatus according to an embodiment of the present invention; FIG. FIG. 4 is a diagram showing packetization of voice data of the voice receiving device according to the embodiment of the present invention; FIG. 4 is a diagram showing buffering of voice data of the voice receiving device according to the embodiment of the present invention; FIG. FIG. 6 is a diagram showing a relationship between reception buffer means and reproduction of the audio receiving device of FIG. 6 FIG. 6 is a diagram showing an increase in the amount of audio data of the audio receiving device of one embodiment of the present invention FIG. FIG. 8 is a diagram showing a data amount reduction of the audio data of the audio receiving device according to the embodiment. FIG. 8 is a diagram showing a reproduced audio waveform by waveform processing correction of the audio receiving device according to the embodiment of the present invention. The reproduced audio waveform by the waveform processing correction of the audio FIG. 10 is a block diagram showing a real-time audio buffer control device of an audio receiving device according to another embodiment of the present invention. FIG. 11 shows a conventional real-time audio buffer control device. FIG. 12 is a diagram showing a relationship between a reception buffer and a reproduction of a conventional real-time audio buffer control device. FIG. 13 is a diagram showing a reproduction audio waveform of a conventional real-time audio buffer control device. Macro view of the reproduced audio waveform of the audio buffer controller [Explanation of the symbols]
REFERENCE SIGNS LIST 1 audio receiving device 2 network 3 audio transmitting device 11 real-time audio buffer control device 111 packet receiving means 112 receiving buffer means 113 receiving buffer monitoring means 114 audio waveform data waveform processing correction means 131 compressed audio decoding means 12 audio reproducing means 13 real-time audio Buffer control device 200 real-time audio buffer control device 201 reception buffer 202 reproduction control module 203 switcher 204 high-speed reproduction module 205 audio decoder 300 audio reproduction module

Claims (2)

Receiving buffer means for temporarily storing received audio data, and an upper limit value and a lower limit value set in advance, and the amount of use of the receiving buffer means falling below the lower limit value, or the use of the receiving buffer means Receiving buffer monitoring means for detecting and outputting that the amount has exceeded the upper limit, and when the receiving buffer monitoring means has output that the amount of use of the receiving buffer means has fallen below the lower limit, the receiving buffer When the reception buffer monitoring means outputs that the amount of use of the reception buffer means has exceeded the upper limit, the reception buffer means outputs Waveform processing and correction means for performing waveform processing correction on the selected audio data to reduce the data amount. The audio buffer controller. If the received audio data is compressed audio data obtained by data compression, the audio data decoding apparatus further comprises a compressed audio decoding unit that decodes the compressed audio data, restores the audio data, and outputs the decoded audio data to the reception buffer unit. 2. The real-time audio buffer control device according to 1.

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