JP2010035123A - Communication terminal device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a communication terminal device of which the processing load during picture information communication is reduced. <P>SOLUTION: The communication terminal device for performing image communication according to the ITU-T recommendation T.38 communication, includes: a notification means for notifying a counter terminal about the total packet number of image data to be transmitted in image transmission; and a receiving means which, when the total packet number of image data is reported from the counter terminal in image reception and the packets as many as the reported total packet number from a first packet of the image data are received in receiving the image data, does not decode contents in a predetermined part of the received packets. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to ITU-T Recommendation T.30. The present invention relates to a communication terminal device that performs image communication by 38 communication.

  Conventionally, ITU-T recommendation T.I. T.38 which performs image communication by 38 communication. The 38 real-time FAX (hereinafter referred to as “IP-FAX”) is basically an ITU-T recommendation T.38. 30 group 3 facsimile procedures are implemented on the IP network to perform image communication. In this IP-FAX, image data is packetized and transmitted / received via an IP network.

Here, the internal structure of the packetized information can be divided into the following two.
A: Packet packet sequence number, data content, etc., unique for each packet in the image data group B: Message type, data type, etc., in the image data group, the same value is stored in multiple packets thing

For example, when an image of one page is transmitted by IP-FAX, the image data is usually transmitted by being divided into several hundred packets or more. Of these, the sequence number and the data contents are different in each packet, but the message type (for example, a bit string representing “v17-14400”) or the data type (for example, “t4-non-ecm-data”). Is the same value in all image data packets.
Japanese Patent No. 4033812

  The above is the ITU-T recommendation T.30. 38, but encoding and decoding information that does not change in several hundred packets (thousands of packets and tens of thousands of packets) increases the processing load on the communication terminal device side. As a result, the communication speed may be hindered, and in some cases, there may be a problem that the network line capability cannot be fully exhibited.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a communication terminal device that can reduce the processing load during image information communication.

  The present invention relates to ITU-T Recommendation T.30. 38. A communication terminal device for performing image communication by 38 communication, a notification means for notifying the other terminal of the total number of image data packets to be transmitted at the time of image transmission, and a total number of image data packets from the other terminal at the time of image reception. When notified, when receiving the image data, the receiving unit does not decode the contents of a predetermined portion of the received packet when receiving the packet of the notified total number of packets from the first packet of the image data. It is a thing.

  Further, prior to image communication, the communication function is negotiated with the other terminal, and the other terminal has a function that does not decode the contents of a predetermined portion of the received packet of the image data when transmitting the image. If found, it further comprises transmission image data generation means for inserting an appropriate bit string as the contents of the predetermined portion of the packet carrying the image data.

  Further, prior to image communication, the communication function is negotiated with the other terminal, and the other terminal has a function that does not decode the contents of a predetermined portion of the received packet of the image data when transmitting the image. If found, it further comprises transmission image data generation means for inserting a bit string having a data length of 0 as the content of the predetermined portion of the packet carrying the image data.

  When the image is received, if the total packet count value of the image data received by the receiving unit is larger than the total number of received packets, the retransmission request unit that requests the other terminal to retransmit the total number of image data packets; When transmitting a request for retransmission of the total number of image data packets from the other terminal during image transmission, the apparatus further includes a total packet number retransmission means for notifying the other terminal of the total number of packets of image data for which transmission has been completed.

  Further, when the image is received, if the total packet count value of the image data received by the receiving unit is smaller than the total number of received packets, a retransmission request unit that requests the partner terminal to retransmit the total number of image data packets, When transmitting a request for retransmission of the total number of image data packets from the other terminal during image transmission, the apparatus further includes a total packet number retransmission means for notifying the other terminal of the total number of packets of image data for which transmission has been completed.

  Further, when receiving an image, if the total number of packets retransmitted from the counterpart terminal and the total packet count value are different, image data retransmission request means for requesting the counterpart terminal to retransmit the image data,

  At the time of image transmission, it is further provided with an image retransmission means for retransmitting the image data when a retransmission of the image data is requested from the counterpart terminal.

  Further, prior to image communication, the communication function is negotiated with the other terminal, and the other terminal has a function that does not decode the contents of a predetermined portion of the received packet of the image data when transmitting the image. If it is found, the registered address book information stores information indicating that the function is provided.

  In addition, ITU-T recommendation T.I. 38. A communication terminal device for performing image communication by 38 communication, a notification means for notifying a partner terminal of the total number of packets per page of image data to be transmitted at the time of image transmission, and a page of image data from the partner terminal at the time of image reception When the total number of packets for each page is notified, when receiving the packet of the total number of packets notified from the first packet of the image data at the time of receiving the image data of each page, the content of the predetermined portion of the received packet Receiving means that does not perform decoding.

  In addition, ITU-T recommendation T.I. 38. A communication terminal apparatus for performing image communication by 38 communication, wherein when transmitting an image in ECM mode, a notification means for notifying the partner terminal of the total number of packets for each block of image data to be transmitted; When the total number of packets for each block of image data is notified from the terminal, when the packet of the notified total number of packets is received from the first packet of the image data when receiving the image data of each block, the received A receiving unit that does not decode the contents of a predetermined portion of the packet is provided.

  Therefore, according to the present invention, the receiving terminal notifies the total number of image data packets to be transmitted to the receiving side, including during multi-page communication and ECM mode communication. By enabling the image data packet to be processed without decoding the area in which the value is stored, the processing load on the apparatus can be reduced.

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

  FIG. 1 shows an example of a communication system according to an embodiment of the present invention.

  In this communication system, a transmitting T38 terminal device TX and a receiving T38 terminal device are connected via a network NW made up of an IP network such as the Internet, and the T38 terminal device TX is connected to a T38 via a network NW. A call is made to the terminal device RX, a communication path is set up with the T38 terminal device RX, T38 communication is performed, and transmission image information is transmitted.

  Here, the T38 terminal devices TX and RX are respectively ITU-T recommendation T.264. 38 has a function of performing image information communication by applying the communication protocol defined in No. 38. As is well known, for the call setup procedure, SIP (Session Initiation Protocol) or ITU-T Recommendation H.264 is used. 323 is applied, and the communication procedure using the set communication path is ITU-T recommendation T.323. 38 applies. SIP, Recommendation H. 323 and Recommendation T.W. The communication procedure such as each recommendation such as 38 and the signal used are well-known techniques, and thus a detailed description thereof will be omitted.

  FIG. 2 shows a configuration example of the T38 terminal devices TX and RX.

  In the figure, a system control unit 1 performs various control processes such as a control process for each part of the T38 terminal devices TX and RX and a T38 communication procedure procedure process. The control processing program executed by the computer and various data necessary for executing the processing program are stored, and the work area of the system control unit 1 is configured. The parameter memory 3 includes the T38 terminal device TX. , RX for storing various kinds of information (for example, address book information), and the clock circuit 4 outputs current time information.

  The scanner 5 is for reading a document image at a predetermined resolution, the plotter 6 is for recording and outputting an image at a predetermined resolution, and the operation display unit 7 is used for the T38 terminal devices TX, RX. It consists of various operation keys and various displays.

  The encoding / decoding unit 8 encodes and compresses the image signal, and also decodes the encoded and compressed image information into the original image signal. The image storage device 9 performs encoding and compression. This is for storing a large number of image information in the selected state.

  The network interface circuit 10 is for connecting the T38 terminal devices TX and RX to the network NW, and the network transmission control unit 11 transmits various data to and from other data terminal devices via the network NW. For performing communication control processing of various predetermined protocol suites for exchanging messages. Here, the network interface circuit 10 and the network transmission control unit 11 are connected to the above-described SIP, recommendation H.264. 323 and Recommendation T.W. A means for realizing each communication procedure of 38 is configured.

  The system control unit 1, the system memory 2, the parameter memory 3, the clock circuit 4, the scanner 5, the plotter 6, the operation display unit 7, the encoding / decoding unit 8, the image storage device 9, and the network transmission control unit 11 Are connected to the internal bus 12, and data exchange between these elements is mainly performed via the internal bus 12.

  FIG. 3 shows a structure of a T38 packet used when image information data is transmitted from the transmitting T38 terminal apparatus TX to the receiving T38 terminal apparatus RX via the set communication path after the communication path is set. An example is shown. The figure shows the configuration of a T38 packet when communicating using UDP, but the IFP packet has the same configuration even when communicating using TCP.

  In this case, the image information data is divided into several hundred or more IFP packets (Internet facsimile protocol packets) and transmitted. This IFP packet includes a sequence number (order number), a message type, a data type, data, and the like. Among these, the sequence number and the data content differ in each packet, but the message type (for example, a bit string representing “v17-14400”) or the data type (for example, “t4-non-ecm-data”). The same value is stored in all IFP packets.

  In this way, encoding and decoding information that does not change with hundreds of IFP packets carrying image information data increases the processing burden on the T38 terminal devices TX and RX and may affect the communication speed.

  Therefore, in this embodiment, the processing load on the receiving T38 terminal apparatus RX is notified from the transmitting T38 terminal apparatus TX to the receiving T38 terminal apparatus RX by notifying the total number of IFP packets to be transmitted. Can be reduced.

  FIG. 4 shows an example when the number of packets is notified from the T38 terminal apparatus TX to the T38 terminal apparatus RX.

  In this case, SIP is used as the call control protocol. Therefore, the TFP terminal device TX on the transmission side uses the INFO message of SIP, and the IFP packet that carries the image information data to the T38 terminal device RX on the reception side. The total number of notifications has been made.

  The notification of the total number of IFP packets that carry this image information data is T.264. You may carry out in 38 data transmission / reception procedures.

  FIG. 5 shows an example of processing of the T38 terminal apparatus RX on the receiving side in this case.

  After the call control message is exchanged and the call setting is completed (process 101), the total number of IFP packets carrying image information data is notified from the transmitting T38 terminal device TX before the image data is received. If this is the case (the result of determination 102 is YES), the T38 terminal apparatus RX stores the message type and data type in the image data packet for the second and subsequent notified image data packets. Decoding is not performed on the existing location (process 103).

  On the other hand, when the total number of IFP packets carrying the image information data is not notified from the transmitting T38 terminal apparatus TX before the image data is received and the result of the decision 102 is NO, the recommendation T.264 is used. All the IFP packets that carry the image information data as 38 are set as decoding targets (process 104).

  Therefore, in this case, when the total number of IFP packets is notified, the receiving T38 terminal RX decodes the message type and the data type for the first IFP packet, but the second and later Since the IFP packet is not decoded for the message type and the data type, the processing burden on the receiving T38 terminal apparatus RX can be greatly reduced.

  When the receiving T38 terminal apparatus RX has the function shown in FIG. 5, the transmitting T38 terminal apparatus TX performs an encoding process on a data portion that is not decoded by the receiving T38 terminal apparatus RX. If an appropriate bit string having a required length is inserted instead of generating data, the processing burden on the transmitting T38 terminal apparatus TX can be reduced.

  An example of processing of the T38 terminal TX on the transmission side in that case is shown in FIG.

  After the call control message is exchanged and the call setting is completed (process 201), it is negotiated with the partner terminal whether or not it corresponds to the method of this function (process 202). This negotiation procedure can be realized, for example, by exchanging INFO messages when SIP is used as the call control procedure.

  If the receiving side supports the method of this function (the result of determination 202 is YES), the message type and the data type are encoded for the first of the IFP packets that carry the image information data. In addition to setting the processing result data, the IFP packets from the second to the (total number of packets) -th IFP packet are not encoded at the location where the message type and data type in the IFP packet are stored, For example, a bit string of all 0s is inserted (process 204).

  On the other hand, when the reception side does not support the method of this function and the result of determination 202 is NO, the recommendation T.30 is used. As shown in FIG. 38, the message type and data type stored in the IFP packet are encoded (process 205).

  By the way, in the above-described embodiment, when the receiving T38 terminal device RX has the function shown in FIG. 5, the transmitting T38 terminal device TX does not decode data in the receiving T38 terminal device RX. For the portion, data is not generated by encoding processing, but an appropriate bit string having a necessary length is inserted. However, the length of a data portion that is not decoded by the T38 terminal device RX on the receiving side It is possible to arrange 0 data, that is, no data is inserted into the data portion.

  In this case, since the data length of the IFP packet from the second to the last IFP packet carrying the image information data is shortened by the message type and the data type, the transmission side T38 terminal device TX to the reception side T38 terminal The data amount of the IFP packet carrying the image information data transmitted to the device RX4 can be greatly reduced, and the traffic on the network NW can be reduced.

  An example of processing of the T38 terminal TX on the transmission side in that case is shown in FIG.

  After the call control message is exchanged and the call setting is completed (process 301), it is negotiated with the partner terminal whether or not it corresponds to the method of this function (process 302). This negotiation procedure can be realized, for example, by exchanging INFO messages when SIP is used as the call control procedure.

  If the receiving side is compatible with the method of this function (the result of determination 302 is YES), for the first IFP packet that carries image information data, the message type and data type are encoded, The data of the processing result is set, and for the IFP packets from the second to the (total number of packets) notified, the data of data length 0 is inserted into the message type and data type in the IFP packet (processing) 304).

  On the other hand, when the reception side does not support the method of this function and the result of determination 302 is NO, the recommendation T.30 is used. As shown in FIG. 38, the message type and data type stored in the IFP packet are encoded (process 205).

  By the way, the number of image data packets actually transmitted from the T38 terminal device TX on the transmission side has become larger than the total number of image data packets first notified from the T38 terminal device TX to the T38 terminal device RX on the reception side. In this case, the T38 terminal apparatus RX cannot know this and cannot determine whether or not to make an error.

  Therefore, when the T38 terminal apparatus RX receives more image data packets than the total number of image data packets notified first, the T38 terminal apparatus RX notifies the T38 terminal apparatus TX again of the total number of image data packets. The T38 terminal apparatus TX again notifies the T38 terminal apparatus RX of the total number of image information data packets so that the T38 terminal apparatus RX can detect that the total number of image information data packets has been changed. It is preferable to make it.

  An example of processing of the receiving T38 terminal apparatus RX in this case is shown in FIG.

  After the call control message is exchanged and the call setting is completed (process 401), the total number of IFP packets carrying image information data is not notified from the transmitting T38 terminal device TX before receiving the image data. If the result of determination 402 is NO, recommendation T. All the IFP packets carrying the image information data as 38 are set as decoding targets (process 403).

  Further, when the total number of IFP packets carrying the image information data is notified from the transmitting T38 terminal device TX before receiving the image data, and when the result of determination 402 is YES, the T38 terminal device RX For the second and subsequent image data packets up to the number of notified packets, the part where the message type and data type in the image data packet are stored is not decoded (process 404).

  Next, it is checked whether or not the decoding result of the (total number of packets + 1) -th packet is an image data packet (IFP packet) (decision 405). When the decoding result of the (total number of packets + 1) -th packet is an IFP packet, and the result of determination 405 is YES, the T38 terminal apparatus RX has received the receiving terminal more than the total number of image data packets first notified. It is determined that the number of image data packets actually received is larger.

  In this case, the total number of image data packets actually received is stored (process 406), and the transmission side T38 terminal apparatus TX is requested to retransmit the total number of image data packets (process). 407), the total number of packets is received again from the T38 terminal apparatus TX (process 408).

  Then, the total number of re-notified packets is compared with the number of actually received image data packets obtained in processing 406 to check whether they match (decision 409). When the result of determination 409 is YES, this image information receiving operation is normally terminated. On the other hand, when the result of determination 409 is NO, this image information reception operation ends with an error (processing 410).

  Further, when the decoding result of the (total number of packets + 1) -th packet is not an image data packet and the result of determination 405 is NO, the total number of image data packets notified first and the actual packet number are actually Since the total number of packets of the received image data matches, this image information reception operation ends normally.

  In this way, in this case, if the total number of image data packets received by the receiving T38 terminal apparatus RX is greater than the initially notified number, the T38 terminal apparatus RX The apparatus TX is requested to retransmit the total number of image data packets, and the number of retransmitted packets is compared with the number of actually received image data packets to determine whether or not image information communication has been performed normally. Since it can be determined, the reliability of image information communication can be improved.

  FIG. 9 shows a sequence example in which the total number of image data packets is notified again. In this case, SIP is used as the call control protocol. Therefore, the SIP INFO message is used to request retransmission of the total number of image data packets and re-notification of the total number of image data packets. . Re-notification of the total number of packets may be performed using a 38-packet communication procedure.

  By the way, the number of image data packets actually transmitted from the T38 terminal device TX on the transmission side is smaller than the total number of image data packets first notified from the T38 terminal device TX to the T38 terminal device RX on the reception side. In this case, the T38 terminal apparatus RX cannot know this and cannot determine whether or not to make an error.

  Therefore, when the T38 terminal apparatus RX receives a smaller number of image data packets than the total number of image data packets notified first, the T38 terminal apparatus RX notifies the T38 terminal apparatus TX again of the total number of image data packets. The T38 terminal apparatus TX again notifies the T38 terminal apparatus RX of the total number of image information data packets, and the T38 terminal apparatus RX can detect that the total number of image information data packets has been changed. It is preferable to do so.

  An example of processing of the receiving T38 terminal apparatus RX in this case is shown in FIG.

  After the call control message is exchanged and the call setting is completed (process 501), the total number of IFP packets carrying image information data is not notified from the transmitting T38 terminal device TX before receiving the image data. If the result of determination 502 is NO, recommendation T. All the IFP packets carrying the image information data in 38 ways are set as decoding targets (process 503).

  Further, when the total number of IFP packets carrying the image information data is notified from the transmitting T38 terminal device TX before receiving the image data, and when the result of determination 502 is YES, the T38 terminal device RX For the second and subsequent notified image data packets up to (total number of packets −1), the message type and data type stored in the image data packet are not decoded (processing 504). ).

  Next, it is checked whether or not the decoding result of the (total number of packets) -th packet is an image data packet (IFP packet) (decision 505). When the decoding result of the (total number of packets) -th packet is not an IFP packet and the result of determination 505 is NO, the T38 terminal apparatus RX does not actually receive the total number of image data packets notified first. It is determined that the number of received image data packets is smaller.

  In this case, the total number of image data packets actually received is stored (process 506), and the transmission side T38 terminal apparatus TX is requested to retransmit the total number of image data packets (process). 507), the total number of packets is received again from the T38 terminal apparatus TX (process 508).

  Then, the total number of re-notified packets is compared with the number of actually received image data packets obtained in processing 506, and it is checked whether they match (decision 509). When the result of determination 509 is YES, this image information receiving operation is normally terminated. On the other hand, when the result of determination 509 is NO, this image information receiving operation is terminated with an error (processing 510).

  When the decoding result of the (total number of packets) -th packet is an image data packet and the result of determination 505 is NO, the total number of image data packets notified first and the image data actually received Therefore, the image information receiving operation is normally terminated.

  In this way, in this case, if the total number of image data packets received by the receiving T38 terminal apparatus RX is less than the initially notified number, the T38 terminal apparatus RX The apparatus TX is requested to retransmit the total number of image data packets, and the number of retransmitted packets is compared with the number of actually received image data packets to determine whether or not image information communication has been performed normally. Since it can be determined, the reliability of image information communication can be improved.

  By the way, as described above, when the number of IPF packets received by the receiving T38 terminal apparatus RX does not match the total number of packets notified from the transmitting T38 terminal apparatus TX, the T38 terminal apparatus RX The total number of packets is received again from the apparatus TX, but when the total number of retransmitted packets and the total number of packets actually received do not match and a communication error is determined, the T38 terminal apparatus RX receives the T38 terminal apparatus TX. On the other hand, by requesting retransmission of image information, the reliability of communication can be further improved.

  FIG. 11 shows a sequence example in that case.

  If the T38 terminal apparatus RX on the receiving side compares the total number of image data packets notified again with the number of image data packets actually received, and the number is different, the T38 terminal apparatus TX on the transmitting side again Requests transmission of image data packet.

  When the T38 terminal device TX designates a partner terminal, the T38 terminal device TX refers to pre-registered address book information (not shown), presents a list of registered destinations to the user, and the user displays the list. It is equipped with an address function that allows the user to specify a destination with a simple operation.

  Therefore, when the transmitting T38 terminal device TX detects that the receiving terminal is compatible with the method of this function, this information is registered for the address book information of the destination, and the communication is performed at the next and subsequent communications. It is possible to omit the negotiation of whether or not the function method is supported.

  An example of the processing at this time is shown in FIG.

  After the call control message is exchanged and the call setting is completed (process 601), it is negotiated with the partner terminal whether or not the method of this function is supported (process 602). This negotiation procedure can be realized, for example, by exchanging INFO messages when SIP is used as the call control procedure.

  If the receiving side supports the method of this function (the result of the determination 602 is YES), information indicating that the method corresponds to the method of this function is stored in the destination information of the receiving side at that time (processing) 603).

  As a result, it is possible to confirm that the partner terminal is compatible with the method of this function before the call control procedure is performed thereafter, so that the negotiation procedure can be omitted in the subsequent communication. Can be improved.

  FIG. 13 shows an example when the number of packets for each page is notified from the T38 terminal apparatus TX to the T38 terminal apparatus RX. In this example, SIP is used as the call control protocol. H.323 or other protocols may be used.

  T.A. In the 38 communication phase, the transmission procedure signals of DIS and DCS for exchanging the capability are exchanged first, then the image information (PIX) of the first page is transmitted, and then the transmission and reception results of the first page are exchanged. Perform (MPS, MCF). Thereafter, the image information of the second page is transmitted.

  In this example, the total number of packets in the page is notified using the first packet for transmitting image information. For example, the total number of subsequent image data packets is stored and notified in the first byte of the image information storage portion in the IFP packet existing in the first packet for transmitting the image information.

  In the above-described example, the total number of packets in the page is notified using the image information packet, but the total number of packets in the page is determined using other signals (non-standard signals such as DCS, EOM, and MPS). You may be notified. For details of facsimile communication modes such as the ECM mode, details of each transmission procedure signal, etc., refer to Recommendation T.30. See 38 (or ITU-T recommendation T.30).

  FIG. 14 shows an example of a case where a receiving terminal declares using a SIP call control message that it has a function of not decoding the contents of a predetermined portion of a received packet of image data.

  As shown in this example, the declaration is made by adding a character string “special” to the User-Agent header of the SIP message header. A SIP INVITE message including this header is transmitted from the transmission terminal to the reception terminal, and the reception terminal includes the header of the SIP 200 OK message, thereby confirming that the function of the present invention is used.

  FIG. 15 shows an example of processing of the T38 terminal apparatus RX on the receiving side in this case.

  After the call control message is exchanged and the call setting is completed (process 701), if it is determined by negotiation that the terminal is compatible with the method of this function (the result of determination 702 is YES), the T38 terminal device RX obtains the total number of packets of the corresponding page from a predetermined location of the first image data packet in the page, and in the image data packet for the second and subsequent image data packets up to the notified number of packets. The location where the message type and data type are stored is not decoded. If there are a plurality of pages, the same processing is performed for the number of pages (loop of processing 703, 704 and determination 705).

  On the other hand, when the T38 terminal TX on the transmission side is not a terminal compatible with the method of this function (the result of the determination 702 is NO), the entire image data packet is subject to decoding as recommended (processing 706).

  FIG. 16 shows an example of processing of the T38 terminal device RX on the receiving side when image communication is performed in the ECM mode. In the ECM mode, data is exchanged in units of a predetermined data length (ECM block) (see Recommendation T.38).

  After the call control message is exchanged and the call setting is completed (process 801), when it is determined by negotiation that the terminal is compatible with the method of this function (the result of determination 802 is YES), the T38 terminal device RX obtains the total number of packets of the block from a predetermined location of the first image data packet in the block (ECM block), and for the second and subsequent image data packets up to the number of notified packet data, The part where the message type and the data type in the image data packet are stored is not decoded. When there are a plurality of blocks, the same processing is performed for the number of blocks (loops of processing 803, 804 and determination 805).

  As a result of the negotiation, if it is not determined that the method of this function is to be performed (the result of determination 802 is NO), the entire image data packet is subject to decoding as recommended (processing 806).

  FIG. 17 shows an example of processing of the T38 terminal device TX on the transmission side when performing multi-page communication.

  After exchanging the call control message and completing the call setting (process 901), if it is determined by negotiation that the terminal is compatible with the method of this function (the result of determination 902 is YES), the transmission side The T38 terminal apparatus TX stores the total number of image data packets scheduled to be transmitted in the page in the first image data packet in the page and transmits the packet (process 903).

  For the second and subsequent image data packets up to the total number of packets notified, the message type and data type stored in the image data packet are not encoded, and for example, a bit string of all zeros is inserted. (Process 904).

  The above processes 903 and 904 are executed for all pages (NO loop of decision 905).

  On the other hand, if it is not determined that the method of this function is to be executed as a result of the negotiation (the result of the determination 902 is NO), the recommendation T.30 is used. The message type and the data type stored in the image data packet are encoded as in 38 (process 906).

  FIG. 18 illustrates an example of processing of the T38 terminal apparatus TX on the transmission side when performing communication in the ECM mode.

  After the call control message is exchanged and the call setup is completed (process 1001), when it is determined by negotiation that the terminal is compatible with the method of this function (the result of determination 1002 is YES), the transmission side The T38 terminal apparatus TX stores the total number of image data packets scheduled to be transmitted in the block (ECM block) in the first image data packet and transmits the packet (process 1003).

  For the second and subsequent image data packets up to the total number of packets notified, the message type and data type stored in the image data packet are not encoded and no information is inserted ( Process 1004).

  The above processes 1003 and 1004 are executed for all pages (NO loop of decision 1005).

  On the other hand, if it is not determined that the method of this function is to be executed as a result of the negotiation (the result of the determination 1002 is NO), the recommendation T.264 is used. The part where the message type and the data type in the image data packet are stored is encoded in 38 ways.

  By the way, the number of image data packets actually transmitted from the T38 terminal device TX on the transmission side has become larger than the total number of image data packets first notified from the T38 terminal device TX to the T38 terminal device RX on the reception side. In this case, the T38 terminal apparatus RX cannot know this and cannot determine whether or not to make an error.

  Therefore, when the T38 terminal apparatus RX receives more image data packets than the total number of image data packets notified first, the T38 terminal apparatus RX notifies the T38 terminal apparatus TX again of the total number of image data packets. The T38 terminal apparatus TX again notifies the T38 terminal apparatus RX of the total number of image information data packets so that the T38 terminal apparatus RX can detect that the total number of image information data packets has been changed. It is preferable to make it.

  FIG. 19 shows another example of processing of the receiving T38 terminal apparatus RX in this case.

  After exchanging the call control message and completing the call setting (process 1101), if it is determined by negotiation that the terminal does not correspond to the method of this function (the result of determination 1102 is NO), the image data packet is as recommended. All the contents are to be decoded (processing 1103).

  On the other hand, when it is determined by negotiation that the terminal is compatible with the method of this function (the result of determination 1102 is YES), the T38 terminal device RX starts from the predetermined position of the first image data packet in the page to the corresponding page. And the second and subsequent image data packets up to the notified number of packets are not decoded at locations where the message type and data type are stored in the image data packet. If there are a plurality of pages, the same processing is performed for the number of pages (processing 1104).

  If the decoding result of the next packet is an image data packet (the result of determination 1105 is YES), the receiving terminal determines the actual received image data packet rather than the total number of image data packets first notified. Judge that the number is larger.

  In this case, the total number of image data packets actually received is stored (processing 1106), and the T38 terminal apparatus TX on the transmission side is requested to retransmit the total number of image data packets (processing). 1107), the total number of packets is received again from the T38 terminal TX (processing 1108).

  Then, the total number of re-notified packets is compared with the number of actually received image data packets obtained in processing 1106 to check whether they match (decision 1109). When the result of determination 1109 is YES, this image information receiving operation is normally terminated. On the other hand, when the result of determination 1109 is NO, this image information receiving operation ends in error (step 1110).

  Further, when the decoding result of the (total number of packets + 1) -th packet is not an image data packet and the result of determination 1105 is NO, the total number of image data packets notified first and the actual number of packets are actually Since the total number of packets of the received image data matches, this image information reception operation ends normally.

  In this way, in this case, if the total number of image data packets received by the receiving T38 terminal apparatus RX is greater than the initially notified number, the T38 terminal apparatus RX The apparatus TX is requested to retransmit the total number of image data packets, and the number of retransmitted packets is compared with the number of actually received image data packets to determine whether or not image information communication has been performed normally. Since it can be determined, the reliability of image information communication can be improved.

  For the procedure for notifying the total number of image data packets again, see FIG.

  By the way, the number of image data packets actually transmitted from the T38 terminal device TX on the transmission side is smaller than the total number of image data packets first notified from the T38 terminal device TX to the T38 terminal device RX on the reception side. In this case, the T38 terminal apparatus RX cannot know this and cannot determine whether or not to make an error.

  Therefore, when the T38 terminal apparatus RX receives a smaller number of image data packets than the total number of image data packets notified first, the T38 terminal apparatus RX notifies the T38 terminal apparatus TX again of the total number of image data packets. The T38 terminal apparatus TX again notifies the T38 terminal apparatus RX of the total number of image information data packets, and the T38 terminal apparatus RX can detect that the total number of image information data packets has been changed. It is preferable to do so. Refer to FIG. 11 for a sequence example in that case.

  An example of processing of the T38 terminal RX on the receiving side in this case is shown in FIG.

  After exchanging the call control message and completing the call setting (process 1101), if it is determined by negotiation that the terminal does not correspond to the method of this function (the result of determination 1102 is NO), the image data packet is as recommended. All the contents are to be decoded (processing 1103).

  On the other hand, when it is determined by negotiation that the terminal is compatible with the method of this function (the result of determination 1102 is YES), the T38 terminal apparatus RX is notified from the second time onward (total number of packets −1). For the first image data packet, the part where the message type and data type in the image data packet are stored is not decoded (process 1204).

  Next, it is checked whether or not the decoding result of the (total number of packets) -th packet is an image data packet (IFP packet) (decision 1205). When the decoding result of the (total number of packets) -th packet is not an IFP packet and the result of determination 1205 is NO, the T38 terminal apparatus RX does not actually receive the total number of image data packets notified first. It is determined that the number of received image data packets is smaller.

  In this case, the total number of image data packets actually received is stored (process 1206), and the transmission side T38 terminal apparatus TX is requested to retransmit the total number of image data packets (process). 1207), the total number of packets is received again from the T38 terminal apparatus TX (process 1208).

  Then, the re-notified total number of packets is compared with the number of actually received image data packets obtained in processing 1206 to check whether they match (decision 1209). When the result of determination 1209 is YES, this image information receiving operation is normally terminated. On the other hand, when the result of determination 1209 is NO, this image information reception operation is terminated with an error (process 1210).

  When the decoding result of the (total number of packets) -th packet is an image data packet and the result of determination 1205 is NO, the total number of image data packets notified first and the actually received image data Therefore, the image information receiving operation is normally terminated.

  In this way, in this case, if the total number of image data packets received by the receiving T38 terminal apparatus RX is less than the initially notified number, the T38 terminal apparatus RX The apparatus TX is requested to retransmit the total number of image data packets, and the number of retransmitted packets is compared with the number of actually received image data packets to determine whether or not image information communication has been performed normally. Since it can be determined, the reliability of image information communication can be improved.

  In the above-described embodiment, the case where SIP is applied as the call control procedure (call setting procedure) has been described. Even when 323 is applied, the present invention can be applied in the same manner. Moreover, it is not limited to what was demonstrated by embodiment, The method equivalent to these is also contained in the technical scope of this invention.

The block diagram which showed an example of the communication system concerning one Example of this invention. The block diagram which showed the structural example of T38 terminal device TX and RX. An example of the configuration of a T38 packet used when image information data is transmitted from the transmitting T38 terminal apparatus TX to the receiving T38 terminal apparatus RX through the set communication path after the communication path is set. Schematic diagram. The sequence diagram which showed an example at the time of notifying the number of packets from T38 terminal device TX to T38 terminal device RX. The flowchart which showed an example of the process of T38 terminal device RX. The flowchart which showed an example of the process of T38 terminal device TX. The flowchart which showed the other example of the process of T38 terminal device TX. The flowchart which showed the other example of the process of T38 terminal device RX. The sequence diagram which showed an example of the procedure which notifies again the total number of image data packets. The flowchart which showed the further another example of the process of T38 terminal device RX. The sequence diagram which showed an example of the procedure which resends an image data packet after notifying the total number of image data packets again. The flowchart which showed another example of the process of T38 terminal device TX. The sequence diagram which showed an example at the time of notifying the packet number for every page from T38 terminal device TX to T38 terminal device RX. Schematic which showed an example of the SIP message header. The flowchart which showed another example of the process of T38 terminal device RX. The flowchart which showed another example of the process of T38 terminal device RX. The flowchart which showed another example of the process of T38 terminal device TX. The flowchart which showed another example of the process of T38 terminal device TRX. The flowchart which showed another example of the process of T38 terminal device RX. The flowchart which showed another example of the process of T38 terminal device RX.

Explanation of symbols

  TX, RX T38 terminal equipment

Claims (9)

ITU-T recommendation A communication terminal device for performing image communication by 38 communication,
A notification means for notifying the partner terminal of the total number of packets of image data to be transmitted at the time of image transmission;
When receiving the total number of packets of image data from the partner terminal when receiving the image, when receiving the packet of the total number of packets notified from the first packet of the image data when receiving the image data, the received packet A communication terminal device comprising receiving means that does not decode the contents of a predetermined location. Prior to image communication, negotiate communication functions with the other terminal,
When it is found that the counterpart terminal has a function of not decoding the contents of a predetermined part of the received packet of the image data at the time of image transmission, the contents of the predetermined part of the packet carrying the image data are appropriately The communication terminal apparatus according to claim 1, further comprising transmission image data generation means for inserting a bit string. Prior to image communication, negotiate communication functions with the other terminal,
When it is found that the counterpart terminal has a function that does not decode the contents of a predetermined portion of the received packet of image data at the time of image transmission, the data length as the content of the predetermined portion of the packet carrying the image data 2. The communication terminal apparatus according to claim 1, further comprising transmission image data generation means for inserting a bit string of 0. At the time of image reception, if the total packet count value of the image data received by the receiving means is larger than the total number of received packets, the retransmission request means for requesting the partner terminal to retransmit the total number of image data packets,
When transmitting a request for retransmission of the total number of image data packets from the partner terminal during image transmission, the receiver further comprises a total packet number retransmission means for notifying the partner terminal of the total number of packets of image data for which transmission has been completed. The communication terminal device according to claim 1. At the time of image reception, if the total packet count value of the image data received by the receiving means is less than the total number of received packets, the retransmission request means for requesting the partner terminal to retransmit the total number of image data packets,
When transmitting a request for retransmission of the total number of image data packets from the partner terminal during image transmission, the receiver further comprises a total packet number retransmission means for notifying the partner terminal of the total number of packets of image data for which transmission has been completed. The communication terminal device according to claim 1. When receiving an image, if the total number of packets retransmitted from the counterpart terminal is different from the total packet count value, image data retransmission request means for requesting the counterpart terminal to retransmit the image data;
6. The communication terminal apparatus according to claim 4, further comprising image retransmission means for retransmitting image data when retransmission of image data is requested by a counterpart terminal during image transmission. Prior to image communication, negotiate communication functions with the other terminal,
When it is found that the other terminal has a function that does not decode the contents of a predetermined part of the received packet of image data at the time of image transmission, the registered address book information is provided with the function. The communication terminal apparatus according to claim 1, wherein the communication terminal apparatus stores the communication terminal apparatus. ITU-T recommendation A communication terminal device for performing image communication by 38 communication,
A notification means for notifying the partner terminal of the total number of packets for each page of image data to be transmitted during image transmission;
When receiving the image, when the total number of packets per page of image data is notified from the partner terminal, when the image data of each page is received, the packet of the notified total number of packets is received from the first packet of the image data. Then, a communication terminal device comprising receiving means that does not decode the contents of a predetermined location of the received packet. ITU-T recommendation A communication terminal device for performing image communication by 38 communication,
A notification means for notifying the partner terminal of the total number of packets for each block of image data to be transmitted when transmitting an image in the ECM mode;
When receiving an image in the ECM mode, if the total number of packets for each block of image data is notified from the partner terminal, when the image data of each block is received, the number of packets notified from the first packet of the image data A communication terminal device comprising receiving means for receiving a packet and not decoding the contents of a predetermined portion of the received packet.