KR100899810B1 - Apparatus for generating a fixed delay of variable bandwidth multicodec and method therefor - Google Patents

Abstract

Disclosed are a fixed delay generation apparatus and a method for variable band multicodec. Determine the minimum time interval between packets for the received N packets, predict the expected reception time of the packet received N + 1th based on the minimum time interval, and then receive the packet after N + 1st Are decoded and the delay time in the buffer is calculated based on the difference between the extraction time of the data extracted from the stored buffer and the expected reception time, and the correction time is based on the difference between the preset fixed delay time and the delay time in the buffer. By reproducing the corrected speech of silence, the delay variation can be corrected and a fixed delay can be generated.

Description

Apparatus for generating a fixed delay of variable bandwidth multicodec and method therefor}

The present invention relates to a variable band multicodec, and more particularly, to an apparatus and method for correcting a delay variation of a variable band multicodec and generating a fixed delay.

The variable band multicodec refers to a codec for converting natural sound into codec data having a plurality of data rates. For example, the band is divided into narrow band (300 Hz to 3,400 Hz), wide band (50 Hz to 7,000 Hz), audio band (20 Hz to 20,000 Hz), and 8, 12, 14, 16, 18, 20 in each band. A codec that calculates codec data at a data rate of 22, 24, 26, 28, 30, or 32 bps is called a variable band multicodec.

In the Voice over Internet Protocol (VoIP) voice telephony service of the packet network, the bandwidth provided by the network is variable and unpredictable. The 32-bps transmission rate of the variable-band multicodec provides the best sound quality, and the 8-kbps codec transmission rate is the best. In the case of providing low sound quality, if the network bandwidth is large enough to send a high band by using the variable band multi-codec, the transmission band of 32bps is transmitted. Lower the bit rate, such as, ..., etc., so that the sound quality is bad but network delivery is good.

The variable band multicodec has a high sound quality but high probability of transmission loss and delay in a network, and a low transmission rate of sound quality decreases but a low probability of transmission loss and delay in a network.

The reproduction of such variable band multicodecs requires a high performance telephone apparatus. In order to process a variable band multicodec that generates packets at 20msec intervals, the telephone apparatus must complete the encoding and decoding process of the codec within 20msec to enable normal call. In the currently developed terminal with the highest performance, encoding and decoding time of 17 msec is required. However, due to the long time required of the terminal, the encoding and decoding times are inevitably fixed, and it is difficult to control the delay variation or generate a fixed delay with the existing reproduction buffer algorithm controlling the same.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide an apparatus and a method for correcting a delay variation of a variable band multicodec and generating a fixed delay.

In order to solve the above technical problem, an embodiment of the fixed delay generating apparatus according to the present invention, a packet receiving unit for receiving a packet; A delay variation detector for identifying a minimum time interval between packets with respect to a predetermined number of packets, and predicting an expected reception time of a packet received after the predetermined number based on the minimum time interval; A decoder for storing voice data generated by decoding the packets received after the predetermined number in a buffer; The delay time is calculated in the buffer based on the difference between the first extraction time of the voice data and the expected reception time from the buffer, and the correction time is based on the difference between the preset fixed delay time and the delay time in the buffer. Delay calculation unit for calculating; A correction speech reproducing unit for reproducing the silence correction speech during the correction time; And a voice reproducing unit reproducing the voice data stored in the buffer after reproducing the corrected voice.

In order to solve the above technical problem, an embodiment of the method for generating a fixed delay according to the present invention, receiving a packet; Determining a minimum time interval between packets with respect to a predetermined number of packets, and predicting an expected reception time of a packet received after the predetermined number based on the minimum time interval; Storing voice data generated by decoding the packets received after the predetermined number in a buffer; The delay time is calculated in the buffer based on the difference between the first extraction time of the voice data and the expected reception time from the buffer, and the correction time is based on the difference between the preset fixed delay time and the delay time in the buffer. Calculating; Reproducing silenced speech during said correction time; And reproducing voice data stored in the buffer after reproducing the corrected voice.

According to the present invention, when using a variable band multicodec that requires a high performance telephone apparatus in a high quality real-time Internet telephone service, it is possible to maintain a high quality voice call by correcting an initial delay variation and generating a fixed delay of a desired size.

Hereinafter, with reference to the accompanying drawings will be described in detail the apparatus and method for correcting the delay variation of the variable-band multi-codec according to the present invention and generating a fixed delay.

1 is a diagram illustrating a configuration of an embodiment of an apparatus for correcting a delay variation of a variable band multicodec and generating a fixed delay according to the present invention.

Referring to FIG. 1, an apparatus for correcting a delay variation and generating a fixed delay according to the present invention includes a packet receiver 100, a delay variation detector 110, a delay calculator 120, a corrected voice playback unit 130, It consists of a decoding unit 140, a reproduction buffer 150, and an audio reproduction unit 160.

The packet receiving unit 100 receives a voice packet and grasps the reception time. The received packet is typically a User Datagram Protocol (UDP) packet. The packet receiver 100 transmits a predetermined number of packets received from the first call start point to the delay variation detector 110, and delivers the packets received after the predetermined number to the decode 140. The predetermined number of received packets transmitted to the delay variation detection unit 110 can be variously changed and applied according to an exemplary embodiment of the present invention. In general, about 10 packets without important voice information are preferable. Hereinafter, for convenience of explanation, it is assumed that the number of packets transmitted by the packet receiver 100 to the delay variation detector 110 is N.

The decoding unit 140 decodes the packets from the N + 1 th received from the packet receiving unit 100 using variable band multicodecs to make reproducible speech data. The reproduction buffer 150 stores the voice data generated by the decoding unit 140.

The delay variation detector 110 detects the minimum time interval between the packets based on the reception time of the N voice packets received from the packet receiver 100. The delay variation detector 110 calculates an expected reception time of the N + 1 th received packet based on the minimum time interval. For example, when the minimum time interval between the received N packets is Tin, the expected reception time Tin 'of the N + 1th packet is the time obtained by adding the minimum time interval Tin to the Nth packet reception time. .

The delay calculator 120 detects the time Tout and the delay variation detector 110 from which the voice reproducing unit 160 extracts the N + 1 th voice data (ie, the N + 1 th packet) from the reproduction buffer 150. Calculate the difference from the expected reception time (Tin ') of the N + 1 th packet calculated by. The difference between the extraction time Tout of the N + 1 th voice data in the reproduction buffer 150 and the expected reception time Tin 'calculated by the delay calculation unit 120 is that the packet delay time Dbuf in the buffer is obtained. do. An object of the present invention is to generate a fixed delay. Accordingly, the delay calculator 120 calculates a value obtained by subtracting the delay time Dbuf of the buffer from the predetermined fixed delay time Dfix (hereinafter, referred to as a correction time).

The corrected voice reproducing unit 130 reproduces the corrected voice (ie, the silent signal) during the correction time calculated by the delay calculator 120. The data length of the corrected speech reproduced by the corrected speech reproducing unit 130 is obtained by multiplying the corrected time by the length of speech data at the unit time stage.

The voice reproducing unit 160 sequentially reproduces the voice data extracted from the reproducing buffer 150 following the reproducing voice reproducing of the correcting voice reproducing unit 130. That is, even if the voice reproducing unit 160 extracts the N + 1 voice data from the reproduction buffer 150 early, the N + 1th voice data is reproduced after the correction voice is reproduced during the correction time calculated by the delay calculation unit 120. Is played.

2 is a flowchart illustrating an embodiment of a method of correcting a delay variation of a variable band multicodec and generating a fixed delay according to the present invention.

Referring to FIG. 2, when a device according to the present invention (hereinafter referred to as 'the device') receives a voice packet (S200), a predetermined number of voice packets are first received (hereinafter referred to as N for convenience of description). Is used in the process of correcting the delay variation and generating the fixed delay, and playing by decoding from the N + 1 th packet.

Specifically, when the number of received packets is N or less (S210), the apparatus determines a minimum time interval (Tin) between the N packets based on the reception time of the packets that are identified together when receiving the packets (S220). In operation S230, an expected reception time Tin ′ of the N + 1 th packet is calculated based on the minimum time interval Tin.

The apparatus decodes the received packet from the N + 1 th using a variable band multicodec to generate playable voice data (S270) and stores it in a buffer (S280). When the device extracts and plays back the voice data stored in the buffer, the device detects the extraction time (Tout) of the N + 1 th voice data, which is a difference from the estimated reception time (Tin ') of the N + 1 th packet already calculated. The delay time (Dbuf = Tout-Tin ') of the reproduction buffer is calculated (S240). The apparatus calculates the length of the correction speech necessary for the fixed delay by subtracting the delay time Dbuf of the playback buffer from the fixed delay time Dfix (S250). After reproducing the corrected voice (that is, the silent signal) corresponding to the length of the corrected voice (S260), the apparatus extracts and reproduces the audio data from the N + 1th from the buffer (S290).

The invention can also be embodied as computer readable code on a computer readable recording medium. The computer-readable recording medium includes all kinds of recording devices in which data that can be read by a computer system is stored. Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage, and the like, and also in the form of a display by a carrier wave (for example, transmission over the Internet). It includes what is implemented. The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion.

So far I looked at the center of the preferred embodiment for the present invention. Those skilled in the art will appreciate that the present invention can be implemented in a modified form without departing from the essential features of the present invention. Therefore, the disclosed embodiments should be considered in descriptive sense only and not for purposes of limitation. The scope of the present invention is shown in the claims rather than the foregoing description, and all differences within the scope will be construed as being included in the present invention.

1 is a diagram illustrating a configuration of an embodiment of an apparatus for correcting a delay variation of a variable band multicodec and generating a fixed delay according to the present invention.

2 is a flowchart illustrating an embodiment of a method of correcting a delay variation of a variable band multicodec and generating a fixed delay according to the present invention.

Claims (7)

A packet receiver for receiving a packet; A delay variation detector for identifying a minimum time interval between packets with respect to a predetermined number of packets, and predicting an expected reception time of a packet received after the predetermined number based on the minimum time interval; A decoder for storing voice data generated by decoding the packets received after the predetermined number in a buffer; The delay time is calculated in the buffer based on the difference between the first extraction time of the voice data and the expected reception time from the buffer, and the correction time is based on the difference between the preset fixed delay time and the delay time in the buffer. Delay calculation unit for calculating; A correction speech reproducing unit for reproducing the silence correction speech during the correction time; And And a voice reproducing unit reproducing the voice data stored in the buffer after reproducing the corrected voice. The method of claim 1, wherein the packet receiving unit, And outputting the packets up to a predetermined number from the first time point of the packet to the delay variation detector, and outputting the received packets after the predetermined number to the decoder. The method of claim 1, wherein the decoded portion, A fixed delay generation device, characterized in that for decoding the packets using a variable-band multi-codec. Receiving a packet; Determining a minimum time interval between packets with respect to a predetermined number of packets, and predicting an expected reception time of a packet received after the predetermined number based on the minimum time interval; Storing voice data generated by decoding the packets received after the predetermined number in a buffer; The delay time is calculated in the buffer based on the difference between the first extraction time of the voice data and the expected reception time from the buffer, and the correction time is based on the difference between the preset fixed delay time and the delay time in the buffer. Calculating; Reproducing silenced speech during said correction time; And And reproducing voice data stored in the buffer after reproducing the corrected voice. The method of claim 4, wherein the packet receiving step, And determining a reception time of a packet. The method of claim 4, wherein the storing in the buffer comprises: And storing the voice data generated by decoding the packets using the variable band multicodec. Receiving a packet; Determining a minimum time interval between packets with respect to a predetermined number of packets, and predicting an expected reception time of a packet received after the predetermined number based on the minimum time interval; Storing voice data generated by decoding the packets received after the predetermined number in a buffer; The delay time is calculated in the buffer based on the difference between the first extraction time of the voice data and the expected reception time from the buffer, and the correction time is based on the difference between the preset fixed delay time and the delay time in the buffer. Calculating; Reproducing silenced speech during said correction time; And And reproducing voice data stored in the buffer after reproducing the corrected voice. The computer-readable recording medium having recorded thereon a program for executing the method of generating a fixed delay.

Images