Reception data quantity control method in telephone system, device therefor and storage medium recording its method

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to a method, an apparatus, and a storage medium for recording the method of controlling the amount of received data by a real-time data receiving terminal in an Internet videophone system or the like that performs two-way real-time data communication in an IP network such as the Internet. Is.

【0002】

[Conventional technology]

In Internet videophones, in order to reduce the amount of data flowing on the network, it is common to encode (= compress) audio data and image data, then packetize them and send them to the other party (Fig. 12). Therefore, in the Internet videophone, the capabilities of both parties are exchanged at the start of communication, the other party recognizes the reproducible coding method, and the other party transmits the reproducible coding method to perform real-time data. Communication takes place. A typical method for this is the ITU-T H.323 / H.245 method, which is an international standard method for Internet telephones.

【0003】

In voice communication, the amount of data used in real-time data communication differs depending on the voice coding method used, and the input voice data is encoded in a certain amount (= frame) unit. However, the amount of data differs depending on the packet formation unit (frame size). The base value of this packet formation unit is different for each coding method. For example, the G.723.1 method that compresses voice to 6.3 kbps or 5.3 kbps is 30 ms (milliseconds), and the G.729 method that compresses voice to 8 kbps is 10 ms. Normally, it is possible to reduce the number of transmitted packets by encoding and packetizing the voice for each value that is a multiple of the base frame size that is the base. For example, in the case of the G.723.1 method, it is a multiple of 30ms, such as 60ms, 90ms, 120ms. If the packet formation unit is 120 ms, the compressed voice data of G.723.1 for 4 frames will be transmitted to the other party as one voice data packet (Fig. 13).

【0004】

In image communication, the amount of data differs depending on the image coding method used, and the input image data can be packetized in frame units, GOB units, MB units, or a plurality of each as a packet transmission unit. However, the amount of data varies depending on the packet formation unit (Fig. 14). In addition, the frame rate / image quality parameter is determined at the start of image coding, and the image data is encoded by the parameter, but the amount of data also differs depending on the value.

【0005】

In IP network communication, when packetizing compressed real-time data, header data for the communication protocol is added and packetized. However, since the header size is a fixed value regardless of the size of the encoded data, the packet formation unit. The smaller the value, the larger the overhead of the header part because a large number of packets are created, and the larger the amount of data flowing through the network even if the same encoding is used. As an example, Fig. 15 shows the difference in the amount of transmitted data depending on the packet formation unit of voice-coded G.723.1.

【0006】

On the other hand, in an actual Internet communication line, since the amount of data (communication speed) differs depending on the type of line, it is conceivable to use an Internet videophone in an environment where the communication speed is low . Further, even if the same communication line is used, the communication speed may temporarily decrease, such as when the network becomes congested. In such a case, in the case of audio data, it is effective to change the audio coding or increase the packet formation unit to reduce the overhead, and in the case of image data, perform image coding. It is effective to change it, change the frame rate / image quality parameter, increase the packet formation unit, reduce the overhead, and reduce the amount of transmitted data.

【0007】

There is an RTP / RTCP communication control method as a means for the transmitting terminal to recognize the real-time data reception status, and in the RTP / RTCP communication control method, the RTP packet transmitting side adds a sequence number and a time stamp in the RTP header. The sequence number is incremented by 1 for each RTP packet transmitted, and is used by the receiving side to detect packet discard. The time stamp is the time when the RTP header is generated, and the receiving side recognizes the fluctuation of the network by the following formula.

【0008】

S is the time stamp given by the sender, and R is the RTP packet reception time. The difference between the transmission time interval (Sj-Si) and the reception time interval (Rj-Ri) of packets i and j is D (i, j) = (Rj-Ri)-(Sj-Si) = (Rj-Sj)-(Ri-Si) Is. The following calculation is performed each time packets i and i-1 are received.

【0009】

J = J + (| D (i-1, i) | -J) / 16 J indicates packet fluctuation. The real-time data reception status obtained on the receiving side is notified to the transmitting side by an RTCP packet.

【0010】

[Problems to be Solved by the Invention]

However, in the above-mentioned conventional technique, as a notification method when notifying the amount of data to be used, in the H.323 / H.225 method, there is a method of mutually notifying the amount of data not including the header for the communication protocol, but IP Since it does not include the bandwidth of the header such as, it will be different from the actual amount of data. Further, in the RTP / RTCP communication control method, it is possible to notify the transmitting terminal of the real-time data reception status, but it is left to the transmitting terminal whether or not the transmitting terminal changes the amount of transmitted data.

【0011】

Therefore, there is no means for changing the amount of data from the transmitting terminal at the discretion of the real-time data receiving terminal, and the compressed data packet compressed / packetized at the discretion of the transmitting terminal is unilaterally sent.

【0012】

As a result, the amount of received data cannot be changed at the discretion of the receiving terminal depending on the receiving status, and the receiving terminal may be interrupted in sound or distorted in the image. Alternatively, there is a problem that the optimum audio image cannot be provided.

【0013】

According to the above-mentioned conventional technique, the present invention cannot change the amount of received data at the discretion of the receiving terminal, so that the receiving terminal may be interrupted, the image may be disturbed, or the optimum audio image cannot be provided. This was done to solve the problem. In a telephone system such as an Internet videophone, the receiving terminal can control the amount of data received from the transmitting terminal during real-time data communication, resulting in sound interruptions and image distortion. An object of the present invention is to provide a received data amount control method, an apparatus, and a storage medium recording the method, which enables efficient real-time data communication without occurring.

【0014】

[Means for solving problems]

In order to solve the above problems, the received data control method according to the present invention is a telephone system (for example, an Internet telephone system) in a network (for example, an IP network) in which a plurality of terminals each have an address (for example, an IP address) and is accommodated. ), The receiving terminal monitors the sequence number and time stamp (for example, the sequence number and time stamp in the RTP header) given to the received data during real-time data communication, and determines the real-time data reception status as the sequence number and the time. It is determined that the received data amount change processing is necessary when one or both of the packet loss and the fluctuation are recognized from the stamp and one or both of the packet loss and the fluctuation exceed a certain value depending on the real-time data reception status. When the data amount change request is sent to the transmitting terminal and the transmitting terminal recognizes the data amount changing request from the receiving terminal, it can be transmitted and received by the coding method that can be used during a voice call or the coding method. The stage of changing the real-time data transmission data amount by changing the packet formation unit, and if the transmission data amount cannot be changed, the real-time data transmission data amount is not changed and the data amount change refusal is sent to the receiving terminal. It is characterized by having and.

【0015】

Alternatively, in a telephone system in a network in which a plurality of terminals each have an address, the receiving terminal recognizes that a received data amount change operation has been performed by a user operation during real-time data communication. A code that can be used during voice communication when the stage of sending a data amount change request to the transmitting terminal when the received data amount change operation is recognized and when the transmitting terminal recognizes the data amount change request from the receiving terminal. The amount of real-time data transmission data is changed by changing the packet formation unit that can be transmitted and received in the conversion method or the coding method, and if the amount of transmission data cannot be changed, the amount of real-time data transmission data is not changed and the amount of data It is characterized by having a stage of sending a change refusal to the receiving terminal.

【0016】

Alternatively, in a telephone system in a network in which a plurality of terminals each have an address and are accommodated, the receiving terminal monitors the sequence number and time stamp given to the received data during real-time data communication, and the real-time data reception status. The amount of received data is changed when one or both of the packet loss and the fluctuation are recognized from the sequence number and the time stamp, and when one or both of the packet loss and the fluctuation exceed a certain value depending on the real-time data reception status. When it is determined that processing is necessary and a data amount change request is sent to the transmitting terminal, and when the transmitting terminal recognizes the data amount change request from the receiving terminal, a coding method or a coding method that can be used during image communication or The amount of real-time data transmission data is changed by changing the frame rate / image quality parameter in the coding method or the packet formation unit that can be transmitted and received in the coding method, and if the amount of transmission data cannot be changed, the amount of real-time data transmission data. It is characterized in that it has a stage of sending a data amount change refusal to the receiving terminal without changing the data amount.

【0017】

Alternatively, in a telephone system in a network in which a plurality of terminals each have an address and are accommodated, the receiving terminal recognizes that the received data amount change operation has been performed by a user operation during real-time data communication. When the received data amount change operation is recognized, a data amount change request is sent to the transmitting terminal, and when the transmitting terminal recognizes the data amount change request from the receiving terminal, it can be used during image communication. Real-time data transmission data amount is changed by changing the coding method or the frame rate / image quality parameter in the coding method or the packet formation unit that can be transmitted and received in the coding method, and if the transmission data amount cannot be changed, real time. Data transmission It is characterized in that it has a stage of transmitting a data amount change refusal to the receiving terminal without changing the data amount.

【0018】

Similarly, in the received data amount control device of the present invention, in a telephone system in a network in which a plurality of terminals each have an address and are accommodated, the receiving terminal assigns a sequence number to the received data during real-time data communication. And a means of monitoring the time stamp and recognizing one or both of the packet loss and the packet fluctuation from the sequence number and the time stamp as the real-time data reception status, and one of the packet loss and the fluctuation depending on the real-time data reception status. Alternatively, if both of them exceed a certain value, it is determined that the received data amount change process is necessary, and there is a means for sending a data amount change request to the transmitting terminal, and the transmitting terminal has a coding method that can be used during a voice call. And a means for recording the packet formation unit that can be transmitted / received in the coding method, and the data amount change request is recognized when the data amount change request is received from the receiving terminal, and the data amount change request can be transmitted / received in the coding method or the coding method. A means for changing the real-time data transmission data amount by changing the packet formation unit, and a means for sending a data amount change refusal to the receiving terminal without changing the transmission data amount if the transmission data amount cannot be changed. It is characterized by having.

【0019】

Alternatively, in a telephone system in a network in which a plurality of terminals each have an address and is accommodated, the receiving terminal recognizes that the received data amount change operation is performed by the user operation during real-time data communication, and the means. A means for sending a data amount change request to a transmitting terminal when a received data amount changing operation is recognized, a coding method that can be used by the transmitting terminal during a voice call, and a packet formation unit that can be transmitted / received in the coding method. Real-time data transmission data amount by recognizing the data amount change request at the time of receiving the data amount change request from the recording means and the receiving terminal and changing the coding method or the packet formation unit that can be transmitted / received in the coding method. It is characterized by having a means for changing the amount of data to be transmitted and a means for sending a refusal to change the amount of data to the receiving terminal without changing the amount of real-time data transmission data if the amount of transmitted data cannot be changed.

【0020】

Alternatively, in a telephone system in a network in which a plurality of terminals each have an address and are accommodated, the receiving terminal monitors the sequence number and time stamp given to the received data during real-time data communication, and the real-time data reception status. As a means for recognizing one or both of packet loss and packet fluctuation from the sequence number and the time stamp, and when one or both of the packet loss and fluctuation exceed a certain value depending on the real-time data reception status, the amount of received data is changed. It has a means for transmitting a data amount change request to the transmitting terminal when it is determined that processing is necessary, and the transmitting terminal has a coding method that can be used at the time of image communication, a frame rate / image quality parameter in the coding method, or the said. A means for recording a packet formation unit that can be transmitted / received in the coding method, and a data amount change request is recognized when the data amount change request is received from the receiving terminal, and the coding method or the frame rate / image quality parameter in the coding method is used. Alternatively, the means for changing the amount of real-time data transmission data by changing the packet formation unit that can be transmitted / received in the coding method, and the data without changing the amount of real-time data transmission data if the amount of transmission data cannot be changed. It is characterized by having a means for sending a quantity change refusal to a receiving terminal.

【0021】

Alternatively, in a telephone system in a network in which a plurality of terminals each have an address and is accommodated, the receiving terminal recognizes that the received data amount change operation is performed by the user operation during real-time data communication, and the means. A means for sending a data amount change request to the transmitting terminal when the received data amount changing operation is recognized, and a coding method that can be used by the transmitting terminal during image communication, a frame rate / image quality parameter in the coding method, or the said. A means for recording a packet formation unit that can be transmitted / received in the coding method, and a data amount change request is recognized when the data amount change request is received from the receiving terminal, and the coding method or the frame rate / image quality parameter in the coding method is used. Alternatively, a means for changing the real-time data transmission data amount by changing the packet formation unit that can be transmitted / received in the coding method, and a data amount without changing the real-time data transmission data amount if the transmission data amount cannot be changed. It is characterized by having a means for sending a change refusal to a receiving terminal.

【0022】

It is possible to record, provide, or distribute a program for causing a computer to execute a step in the method of controlling the amount of received data in the above telephone system on a storage medium readable by the computer. ..

【0023】

In the present invention, when the receiving terminal itself determines or the user determines from the packet loss or the fluctuation of the packet, the data amount change request is sent to the transmitting terminal, and the transmitting terminal receives the data amount change request. By changing the amount of real-time data sent to the receiving terminal, it is possible for the receiving terminal to control the amount of data received from the transmitting terminal during real-time data communication, causing interruptions in sound and image distortion. Eliminates and enables efficient real-time data communication.

【0024】

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

【0025】

As a first embodiment of the present invention, a block diagram of an Internet videophone terminal is shown in FIG.

【0026】

Reference numeral 101 denotes a device control unit, which controls the following device units in cooperation with each other. Reference numeral 102 denotes an Internet telephone function / control unit, which controls the transmission and reception of data in the Internet telephone, and controls the amount of received data in the receiving terminal. At the transmitting terminal, audio and images from the microphone / camera (103) are input from the input unit (104), converted into digital data by the A / D conversion unit (105), and coded by the coding unit (106). It is converted and passed to the transmission data control unit (112). The transmission data control unit (112) packetizes the encoded data and transmits it to the remote transmission terminal via the communication control unit (114) and the network interface unit (115). On the other hand, in the receiving terminal, the receiving data control unit (111) receives the packet data received via the network interface unit (115) and the communication control unit (114), decodes it by the decoding unit (110), and D / It is converted into an analog signal by the A conversion unit (109), passed through the output unit (108), and presented as audio / image on the speaker monitor (107).

【0027】

In the present embodiment, the Internet videophone terminal records a coding method that the terminal can use during a call and a packet formation unit that can be transmitted and received in the coding method, and when an image is used, the coding method is used. It has a data amount control processing recording unit (113) for recording frame rate / image quality parameters. In addition, the Internet telephone function / control unit (102) has the following 1 or 2 means.

【0028】

1. A means for monitoring the sequence number and time stamp in the RTP header during real-time data communication at the receiving terminal and recognizing packet loss and packet fluctuation from the sequence number and time stamp as the real-time data reception status, and the real-time A means for determining that reception data amount change processing is necessary when packet loss or fluctuation exceeds a certain value depending on the data reception status, and sending a data amount change request to the remote terminal.

【0029】

2. Means for changing the amount of received data by user operation during real-time data communication, means for recognizing that the operation for changing the amount of received data has been performed, and data to the other terminal when the operation for changing the amount of received data is performed. A means of sending a quantity change request.

【0030】

Further, when the own terminal becomes a transmitting terminal, the Internet telephone function / control unit (102) recognizes the data amount change request at the time of receiving the data amount change request, and can transmit and receive in the coding method or the coding method. When using the packet formation unit and image, the means to change the real-time data transmission data amount by changing the frame rate / image quality parameter, and if the transmission data amount cannot be changed, the data amount is changed without changing the transmission data amount. A means of sending a rejection.

【0031】

Examples of the Internet videophone terminal in the present embodiment include a personal computer having a network interface (IF) and having Internet videophone software installed to realize each of the above means, an analog telephone using an analog line, and the like. It may be a terminal connection device connected to a network.

【0032】

FIG. 2 shows an example of a call sequence for requesting a data amount change of an Internet videophone in this embodiment. Further, FIG. 3 shows a processing flow at the time of requesting a change in the amount of data in the present invention.

【0033】

The real-time data receiving terminal determines the amount of data to the transmitting terminal from the packet loss and packet fluctuation during real-time data communication, when the receiving terminal itself, for example, the application itself of the Internet telephone software, or the user makes a judgment. Send a change request packet. When the transmitting terminal receives the data amount change request packet, it determines a real-time data transmission method capable of changing the amount of data to be transmitted, and if it can be changed, transmits the packet by the changeable real-time data transmission method. If this is not possible, the data amount change refusal packet is sent without changing the transmission data amount. An example of a data amount change request packet is shown in FIG. 4, and an example of a data amount change refusal packet is shown in FIG. When the real-time data receiving terminal receives the data amount change refusal packet, the real-time data receiving terminal ends the process of recognizing the reception status or the user operation.

【0034】

In this way, by sending out a data amount change request packet from the receiving terminal, it is possible to reduce sound interruptions and image distortions between Internet videophones in consideration of network conditions, or to provide high-quality audio images. It becomes possible.

【0035】

FIG. 6 shows an example of a second embodiment of the present invention. The present embodiment is an example in which the data amount change processing is performed according to the real-time data reception status during voice communication.

【0036】

A data communication terminal 1 (601) and a data communication terminal 2 (602) are connected on a network (LAN), and the data communication terminal 1 (601) is provided with a microphone (601a) and a speaker (601b), and the Internet. The telephone software (601c) is installed, the data communication terminal 2 (602) is provided with a microphone (602a) and a speaker (602b), and the Internet telephone software (602c) is installed. It is configured.

【0037】

Further, it is assumed that the Internet telephone software is activated in the data communication terminals 1 (601) and 2 (602). The IP address of the data communication terminal 1 (601) is "129.60.26.11", and the IP address of the data communication terminal 2 (602) is "129.60.26.12".

【0038】

The user performs a transmission operation on the data communication terminal 1 (601) with the Internet telephone software, and sets the voice real-time data communication state with the data communication terminal 2 (602). The voice coding method and packet formation unit used in the communication are G.723.1 and 30 msec for both data communication terminals 1 (601) and 2 (602). The data communication terminal 1 (601) measures packet loss and fluctuation of real-time data by the received data control unit from the start of voice real-time data communication. The received data control unit registers packet loss = 3% and fluctuation = 100 as threshold values for requesting a data amount change in advance, and when the threshold values are exceeded, the data amount change process is performed. When the packet loss is measured as 4% in the data communication terminal 1 (601) due to a change in network conditions during real-time data communication, the data communication terminal 1 (601) sends a decrease in the amount of received data to the transmitting terminal. In order to make a request, a data amount change request packet (FIG. 7) containing data amount reduction request information is sent to the data communication terminal 2 (602). When the data communication terminal 2 (602) receives the data amount change request packet, it recognizes it as a data amount reduction request based on the information in the packet, and sends the data amount control processing recording unit (FIG. 8) to reduce the transmitted data amount. Based on the recorded information, the packet formation unit is changed from 30 msec (transmission bit rate of about 22 kb / s) to 120 msec (transmission bit rate of about 10 kb / s), and voice real-time data is transmitted.

【0039】

When the packet loss is measured to be 4% by the data communication terminal 1 (601) again after the received data change processing, the data communication terminal 1 (601) requests the transmitting terminal to reduce the amount of received data. Therefore, a data amount change request packet (FIG. 7) containing data amount reduction request information is sent to the data communication terminal 2 (602). When the data communication terminal 2 (602) receives the data amount change request packet, it recognizes it as a data amount reduction request based on the information in the packet, and sends the data amount control processing recording unit (FIG. 8) to reduce the transmitted data amount. An attempt is made to change the amount of transmitted data based on the recorded information, but since the amount cannot be changed, a data amount change refusal packet is sent to the data communication terminal 1 (601). When the data communication terminal 1 (601) receives the data amount change refusal packet, the data communication terminal 1 (601) ends the process of measuring the packet loss and fluctuation of the real-time data.

【0040】

FIG. 9 shows an example of a third embodiment of the present invention. This embodiment is an example in which the user manually changes the amount of data during voice communication.

【0041】

The data communication terminal 1 (901) is provided with a microphone (901a) and a speaker (901b), and the Internet telephone software (901c) is installed. The data communication terminal 2 (902) is provided with a microphone (902a) and a speaker (902b). , Internet telephone software (902c) is installed, and each constitutes an Internet telephone terminal. A modem (901d) is connected to the data communication terminal 1 (901), a modem (902d) is connected to the data communication terminal 2 (902), and a dial-up connection is made to the Internet provider (903) via the modem. To do. The communication speed of both modems is 28.8kbps.

【0042】

In addition, in the data communication terminal 1 (901) and the data communication terminal 2 (902), it is assumed that the Internet telephone software is started, both are connected to the Internet provider via the modem, and each has acquired an IP address. .. The IP address of the data communication terminal 1 (901) is "129.60.26.11", and the IP address of the data communication terminal 2 (902) is r129.60.26.12.

【0043】

The user performs a transmission operation on the data communication terminal 1 (901) with the Internet telephone software, and sets the voice real-time data communication state with the data communication terminal 2 (902). The voice coding method and packet formation unit used are G.723.1 and 30 msec for both data communication terminals 1 (901) and 2 (902). When the packet formation unit is 30 ms in the G, 723.1 method, the amount of communication data is about 22 kbps, so even if the communication band (28.8 kbps) is for dial-up connection using a modem, there is no data loss and voice can be sent and received normally. Is possible. However, if other data communication is performed during communication and the execution communication band drops to 15 kbps, the data of G.723.1 method / frame packetization size 30 ms cannot be completely sent, and the sound due to data loss A cut will occur. Due to this change in network conditions, the user of the data communication terminal 1 (901) determines that he / she wants to reduce the amount of received data because the sound is interrupted and it is difficult to hear, and the Internet telephone software performs an operation to reduce the amount of received data. In order to request the transmitting terminal to reduce the amount of received data, a data amount change request packet (FIG. 10) containing the data amount reduction request information is transmitted to the data communication terminal 2 (902). When the data communication terminal 2 (902) receives the data amount change request packet, it recognizes it as a data amount reduction request based on the information in the packet, and sends the data amount control processing recording unit (FIG. 11) to reduce the transmitted data amount. Based on the recorded information, the packet formation unit is changed from 30 msec (transmission bit rate of about 22 kb / s) to 120 msec (transmission bit rate of about 10 kb / s), and voice real-time data is transmitted. Since the communication band in this communication mode is about 10 kbps, even if the effective communication band is 15 kbps, voice can be transmitted and received normally without data loss.

【0044】

Although the second and third embodiments show an example during voice communication, they can be similarly applied to voice image communication and image communication. However, during audio-image communication or image communication, the coding method that can be used during image communication, the frame rate / image quality parameter in the coding method, or the packet formation unit that can be transmitted and received in the coding method should be changed. Change the amount of real-time data transmission data. Further, although milliseconds are used as the packet formation unit, the same can be applied even when the number of frame packets is used.

【0045】

Needless to say, some or all the functions of each part of the device shown in FIG. 1 can be realized by using a computer, or the processing procedure shown in FIGS. 2 and 3 can be executed by the computer. In addition, a computer-readable storage medium, such as a FD (floppy disk), MO, etc., can be used to provide a program for realizing the functions of each part of the computer or a program for causing the computer to execute the processing procedure. It can be recorded, provided, and distributed on ROMs, memory cards, CDs, DVDs, removable disks, etc.

【0046】

[Effect of the invention]

As described above, according to the present invention, in a telephone system such as an Internet videophone, when real-time data communication is performed, the receiving terminal itself or the user makes a judgment based on packet loss or packet fluctuation. Since the data amount change request is made to the transmitting terminal and the transmitting terminal changes the data amount to be transmitted when the data amount change request is received, the receiving terminal can control the received data amount from the transmitting terminal. Efficient real-time data communication is possible without sound interruption or image distortion.

[Simple explanation of drawings]

[Figure 1]

It is a block diagram which shows the 1st Embodiment example of the Internet videophone terminal by this invention.

[Figure 2]

It is a figure which shows the example of the sequence at the time of the data amount change request in the said 1st Embodiment example.

[Fig. 3]

It is a processing flow diagram at the time of changing the amount of data in the said 1st Embodiment example.

[Fig. 4]

It is a figure which shows the example of the data amount change request packet in the said 1st Embodiment example.

[Fig. 5]

It is a figure which shows the example of the data amount change refusal packet in the said 1st Embodiment example.

[Fig. 6]

It is a figure which shows the 2nd Embodiment example in this invention.

[Fig. 7]

It is a figure which shows the example of the data amount change request packet in the said 2nd Embodiment example.

[Fig. 8]

It is a figure which shows the example of the data amount control processing recording part in the said 2nd Embodiment example.

[Fig. 9]

It is a figure which shows the 3rd Embodiment example in this invention.

[Fig. 10]

It is a figure which shows the example of the data amount change request packet in the said 3rd Embodiment example.

[Fig. 11]

It is a figure which shows the example of the data amount control processing recording part in the said 3rd Embodiment example.

[Fig. 12]

(a) and (b) are diagrams showing an example of a basic processing sequence in an Internet videophone.

[Fig. 13]

(a) and (b) are diagrams showing an example of a packet formation unit in the G.723.1 method.

[Fig. 14]

(a) and (b) are diagrams showing an example of a packet formation unit in the H.263 method.

[Fig. 15]

(a) and (b) are diagrams for explaining the difference in the amount of transmitted data depending on the packet formation unit.

[Explanation of symbols]

101 ... Device control unit 102 ... Internet telephone function / control unit 103 ... Mike Camera 104 ... Input section 105 ... A / D converter 106 ... Coding section 107 ... Speaker monitor 108 ... Output 109 ... D / A converter 110 ... Decryptor 111 ... Received data control unit 112 ... Transmission data control unit 113 ... Data volume control processing recording unit 114 ... Communication control unit 115 ... Network interface section 601 ... Data communication terminal 1 601a ... Mike 601b ... Speaker 601c ... Internet phone software 602 ... Data communication terminal 2 602a ... Mike 602b ... Speaker 602c ... Internet phone software 901 ... Data communication terminal 1 901a ... Mike 901b ... Speaker 901c ... Internet phone software 901d ... modem 902 ... Data communication terminal 2 902a ... Mike 902b ... Speaker 902c ... Internet phone software 902d ... modem 903 ... Telephone network (Internet provider)