JP2006019954A - Communication device, communication network system, and communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a communication device that easily grasps the time and the like when a plurality of data blocks are processed when a transmitted packet including the plurality of data blocks is transmitted, and also decides the time validity of the transmitted packet. <P>SOLUTION: A data time management part 22 performs processing for writing when respective MPEG packets are inputted by a data input part 11 to a time information storage part 32 and processing in which a data storage processing part 21 writes the MPEG packets inputted by the data input part 11 to a data storage part 31. Then a transmitted packet constitution part 23 reads data of the MPEG packets stored in the data storage part 31 and data on the input time stored in the time information storage part 32 as time information to generate transmitted packets including the validity period information, time information, and MPEG packets. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a communication apparatus and method for transmitting real-time data such as moving images and sounds over a network.

  Recently, real-time transmission of moving image data is widely performed. Real-time transmission is a transmission method in which moving image data transmitted from a transmission device is received and reproduced simultaneously with the reception device. Examples of the format of the moving image data used for the real-time transmission include MPEG2-TS (Moving Picture Experts Group 2-Transport Stream).

  When real-time transmission using MPEG2-TS is performed, the time interval between MPEG2-TS packets generated on the transmission device side must be reproduced on the reception device side within a predetermined allowable error range. If the packet interval cannot be reproduced on the receiving device side within a predetermined allowable error range, the reproduced video in the receiving device may be disturbed. The allowable error range of the packet interval is about 500 ns to several μs, depending on the performance of the MPEG2-TS decoder.

  When this real-time transmission is performed via a wireless LAN, IEEE1394, or the like, data other than actual data to be transmitted, such as data delivery confirmation data, control data, and other data, is also transmitted. That is, in order to secure a certain transmission rate, a device for saving the communication band is required. As one method for conserving this communication band, a method is generally known in which a plurality of MPEG2-TS packets are transmitted together in one transmission packet. However, in order for a receiving apparatus that has received a transmission packet in which a plurality of MPEG2-TS packets are combined to reproduce the above-described packet interval, the transmitting apparatus and the receiving apparatus need to have the same time reference. There is. In order to realize this, there is a transmission method in which the transmission device and the reception device have timers having the same time reference, and the transmission device adds time information based on this timer to each MPEG2-TS packet.

  FIG. 14A shows a time transition of packet generation on the transmission device side, and FIG. 14B shows a transmission packet to be generated. In these drawings, D1 to Dn indicate MPEG2-TS packets, respectively, and T1 to Tn indicate times when D1 to Dn are generated, respectively. As described above, the receiving device needs to reproduce the time interval of T1 to Tn. In the transmission apparatus, when a predetermined number of MPEG2-TS packets, for example, five MPEG2-TS packets D1, D2, D3, D4, and D5 in the example shown in FIG. As shown in 14 (b), MPEG2-TS packets D1, D2, D3, D4, D5, generation times T1, T2, T3, T4, T5 of each MPEG2-TS packet, and transmission packets including header information are generated. To do. This transmission packet is transmitted to the receiving device.

  FIG. 15A shows a transmission packet received by the receiving apparatus, and FIG. 15B shows a time transition of packet reproduction on the receiving apparatus side. D1 to Dn and T1 to Tn are the same as those shown in FIGS. 14 (a) and 14 (b), respectively. When receiving the transmission packet, the receiving device adds a predetermined time α to each of the time information T1, T2, T3, T4, and T5 included in the transmission packet, and D1 at the time of T1 + α, T2 + α, T3 + α, T4 + α, and T5 + α. , D2, D3, D4, and D5 are reproduced. By such control, the receiving device realizes reproduction of each MPEG2-TS packet at the same packet interval as the MPEG2-TS packet interval in the transmitting device.

  In the above transmission method, the timers provided in the transmission device and the reception device need to have the same time reference. As a method for realizing this, there is a method of correcting the timer on the receiving apparatus side using time information added to each MPEG2-TS. Specifically, when the receiving apparatus receives a packet, it extracts time information of each MPEG2-TS packet and corrects the timer using the value.

  Some digital contents encoded by MPEG2-TS and the like need to be copyright protected. In this case, it is necessary to perform device authentication processing between the transmission device and the reception device and to encrypt transmission data. One of the methods for performing such authentication and encryption in transmission by IP (Internet Protocol) is DTCP (Digital Transmission Content Protection) Supplement E. Data generated by the digital content encryption method in this method is called PCP (Protected Content Packets), and is composed of encryption information and encrypted data (Payload). Details of the packet format used in this encryption are shown in FIG.

Payload is a portion encrypted by this encryption method, and includes video data such as MPEG2-TS. The encryption information is composed of the following information. reserved is a portion reserved for the future, and is currently set to 0. C_A is a part for specifying an encryption method. E-EMI is a part indicating the state of this content, and there are states such as Copy-never (copy not possible), Copy-one-generation (only one generation can be copied), and Copy-free (no copy restriction). When content is transmitted, mutual authentication is performed between the transmission device and the reception device, and at the same time, a key used for encryption is exchanged. The transmission device and the reception device encrypt and decrypt the content data based on this key.
WO 03/005674 A1 (International publication date: January 16, 2003) DTCP Volume1 Supplement E Revision 1.0 (Informational Version) (Publication date: November 24, 2003)

  When video data such as MPEG2-TS is transmitted in real time, in a communication environment where the transmission delay time is not guaranteed, the playback time of the video data has already passed when the packet arrives at the receiving device. is there. At this time, the receiving apparatus performs processing for discarding the received packet even though the packet is normally received.

  Here, the time information of the packet is stored in different places according to the type of data to be transmitted (MPEG2-TS, DVC (Digital Video Camera), etc.). For example, since the data length is fixed at 188 bytes in MPEG2-TS, time information is added every 188 bytes, while the data length is fixed at 480 bytes in DVC, so time information is added every 480 bytes. Is added. In other words, the receiving device first needs to follow the procedure of determining the type of received packet, specifying the storage location of time information, and performing packet discard processing according to the time information. Therefore, there is a problem in that the procedure for discarding the packet becomes complicated in the receiving apparatus, and the processing time increases.

  Further, when the data is encrypted as described above, the time information portion is also encrypted. Here, when the correction of the reference time of the timer provided in the receiving device is performed based on the time information of the packet, it is necessary to decode the time information, and there is a problem that the correct reference time cannot be corrected. .

  The present invention has been made in view of the above-described problems, and its purpose is to easily grasp the time for performing processing on each data block when transmitting a transmission packet including a plurality of data blocks. An object of the present invention is to provide a communication device, a communication method, and a communication network system that can simplify the process of determining the temporal validity of a transmission packet.

  In order to solve the above-described problem, a communication device according to the present invention is a communication device that transmits a transmission packet including a plurality of data blocks to a communication device connected via a communication path. The time management means for generating time information related to each of the above, the time limit setting means for generating the expiration date information relating to the expiration date of the transmission packet, and the transmission including the data block, the time information, and the expiration date information A packet composing means for generating a packet.

  In order to solve the above problems, a communication method according to the present invention is a communication method in a communication apparatus that transmits a transmission packet including a plurality of data blocks to a communication apparatus connected via a communication path. Generating the time information related to each of the data blocks, generating the expiration date information regarding the expiration date of the transmission packet, and the data block, the time information, and the expiration date information And a step of generating a transmission packet.

  According to the configuration and method described above, the transmission packet to be transmitted first includes time information related to each data block in addition to the plurality of data blocks to be transmitted. The communication apparatus that has received such a transmission packet can easily grasp the time to perform processing on each data block based on the time information related to each data block.

  Further, the transmitted transmission packet further includes expiration date information regarding the expiration date of the transmission packet. A communication device that has received such a transmission packet can immediately determine whether the transmission packet is still valid in time by checking the expiration date information included in the transmission packet. Become.

  Here, when the expiration date information is not included in the transmission packet, in order to determine whether the transmission packet is valid in terms of time, for example, the above time information is confirmed or a data block is You will check the contents of. Since the time information corresponds to each data block, the storage location in the transmission packet may change depending on the type of the data block. Therefore, there is a problem that processing for determining whether a transmission packet is valid in terms of time becomes complicated. Further, when confirming the contents of the data block, the process for determining the validity is further complicated.

  That is, according to the above-described configuration and method, it is possible to easily grasp the time to perform processing for each data block in the communication device on the receiving side, and to determine the temporal validity of the transmission packet. Can be simplified.

  In the communication device according to the present invention, in the above configuration, the data block is a data block constituting stream data, and the time management unit generates the time information from the stream data. It is good also as a structure produced | generated as the information regarding performed time.

  According to said structure, the information regarding the time when the data block was produced | generated from stream data is contained in this transmission packet corresponding to each data block contained in a transmission packet. Therefore, the communication apparatus that has received such a transmission packet can easily recognize, for example, at what timing the corresponding data block should be output to an upper layer by checking this time information.

  Further, since the stream data is reproduced while being communicated, if transmission is delayed for some reason, data that is not in time for reproduction is generated. Here, as described above, if the transmission packet includes expiration date information, the transmission communication device on the receiving side is not in time for reproduction by first discarding the transmission packet whose expiration date has passed. It is possible to prevent the data from being processed continuously.

  The communication apparatus according to the present invention may be configured such that, in the above configuration, the packet configuration unit generates the transmission packet in a state where the expiration date information is arranged at a predetermined position of the transmission packet.

  According to the above configuration, since the expiration date information is arranged at a predetermined position of the transmission packet, the position of the expiration date information does not change even if, for example, the types of data blocks included in the transmission packet are different. Therefore, the communication device on the receiving side can easily recognize the expiration date information at the same position and determine the validity regardless of the type of transmission packet that includes the data block. . Therefore, it is possible to simplify the determination process of the temporal validity of the transmission packet in the communication device on the receiving side.

  In the communication device according to the present invention, in the configuration described above, the time management unit has a clock function used when generating the time information, and the time limit setting unit generates the expiration date information. It is good also as a structure further provided with the expiration date management means which has a clock function used when doing.

  According to the above configuration, the clock function used when the time information is generated and the clock function used when the expiration date information is generated are provided separately. Therefore, the accuracy and number of digits required for the clock function used when the time information is generated, and the accuracy and number of digits required for the clock function used when the expiration date information is generated, It is possible to achieve performance suitable for each. Therefore, it is possible to reduce the apparatus cost by providing a configuration having the necessary minimum performance.

  Note that another means having a clock function used by the time management means may be provided, or conversely, the time limit setting means itself may have a clock function.

  In the communication device according to the present invention, in the above configuration, the time management unit has a clock function used when generating the time information, and the time limit setting unit stores the expiration date information. When generating, it is good also as a structure which uses the timepiece function which the said time management means has.

  According to the above configuration, the clock function used when the time information is generated and the clock function used when the expiration date information is generated are shared. Therefore, the required components can be reduced.

  The communication apparatus according to the present invention further includes an encryption unit that performs an encryption process on the data block in the configuration described above, and the packet configuration unit includes the data encrypted by the encryption unit. The transmission packet including the block and the time information that has not been encrypted and the expiration date information may be generated.

  According to the above configuration, at least the data block is encrypted in the transmission packet, and the time information and the expiration date information are not encrypted. Therefore, the communication device on the receiving side can recognize the contents of the time information and the expiration date information without performing the decoding process. Therefore, it is possible to quickly process the time information and the expiration date information.

  In order to solve the above problem, a communication device according to the present invention is a communication device that receives a transmission packet including a plurality of data blocks from a communication device according to the present invention via a communication path. A reception packet processing means for determining whether to discard the transmission packet based on expiration date information included in the transmission packet is provided.

  In order to solve the above-described problem, a communication method according to the present invention is a communication device that receives a transmission packet including a plurality of data blocks via a communication path from a communication device that executes the communication method according to the present invention. A communication method is characterized by comprising a step of determining whether or not to discard a transmission packet based on expiration date information included in the received transmission packet.

  According to the above configuration and method, whether or not to discard the transmission packet is determined based on the expiration date information included in the received transmission packet, so whether or not the transmission packet is still valid in time It is possible to immediately determine whether or not. That is, according to the above-described configuration and method, it is possible to easily grasp the time to perform processing for each data block in the communication device on the receiving side, and to determine the temporal validity of the transmission packet. Can be simplified.

  Further, in the above configuration, the communication device according to the present invention includes a data block processing unit that performs processing on the data block included in the transmission block based on the time information included in the received transmission packet; A packet time management unit having a clock function used when the packet processing unit determines the expiration date information, and a data time management unit having a clock function used when the data block processing unit performs processing on the data block; It is good also as a structure further equipped with.

  According to the above configuration, the clock function used when the expiration date information is determined and the clock function used when processing the data block are provided separately. Therefore, the precision and number of digits required for the clock function used when the expiration date information is determined, and the precision and number of digits required for the clock function used when processing the data block are performed. Can be made suitable for each. Therefore, it is possible to reduce the apparatus cost by providing a configuration having the necessary minimum performance.

  Further, in the above configuration, the communication device according to the present invention includes a data block processing unit that performs processing on the data block included in the transmission block based on the time information included in the received transmission packet; Packet time management means having a clock function used when the packet processing means determines the expiration date information, and when the data block processing means performs processing on the data block, the packet time management means A configuration using a clock function may be used.

  According to the above configuration, the clock function used when the expiration date information is determined and the clock function used when the processing on the data block is performed are shared. Therefore, the required components can be reduced.

  In addition, without providing the packet time management means, a data time management means having a clock function used when the data block processing means performs processing on the data block is provided, and the clock function provided in the data time management means is shared. It is good also as composition to do.

  The communication apparatus according to the present invention further includes time correction means for correcting the clock function of the data time management means based on the time information included in the received transmission packet in the above configuration. It is good also as a structure.

  According to the above configuration, the clock function of the data time management unit is corrected based on the time information included in the received transmission packet, so that the deviation from the clock function of the communication device on the transmission side is corrected. Is possible.

  In order to solve the above-described problem, a communication network system according to the present invention includes a communication device on the transmission side according to the present invention and the above-described present invention connected to the communication device on the transmission side via a communication path. And a receiving-side communication device.

  According to the above configuration, the receiving side communication apparatus can easily grasp the time for performing processing on each data block, and simplifies the determination process of the temporal validity of the transmission packet. It is possible to provide a communication network system that makes it possible.

  As described above, the communication device, the communication method, and the communication network system according to the present invention transmit time information related to each of the data blocks, expiration date information regarding the expiration date of the transmission packet, and the data block. Packets are transmitted. As a result, in the communication device on the receiving side, it is possible to easily grasp the time to perform processing for each data block, and it is possible to simplify the determination process of temporal validity of transmission packets. The effect of becoming.

(Embodiment 1)
An embodiment of the present invention is described below with reference to the drawings.

(Configuration of communication network system)
FIG. 3 shows a schematic configuration of the communication network system according to the present embodiment. As shown in the figure, this communication network system transmits stream data and data from a transmission device 3 to a reception device 4 via a transmission side communication device (communication device) 1 and a reception side communication device (communication device) 2. The data is transmitted.

  The transmission device 3 is a device capable of transmitting stream data such as moving image data and other data to an external device. Specifically, the transmission device 3 is configured by a moving image reproduction device such as a DVD (Digital Versatile Disk) player or a HDD built-in DVD player, a broadcast reception device such as a BS / CS tuner, and the like.

  The receiving device 4 is a device that performs processing based on the received stream data and other data. Specifically, the receiving device 4 is configured by, for example, a display device that displays moving image data as received stream data.

  Stream data / data output from the transmission device 3 is transmitted to the transmission-side communication device 1. Then, the transmission side communication device 1 transmits the stream data / data to the reception side communication device 2 via the communication network. When receiving the stream data / data sent from the transmission side communication device 1, the reception side communication device 2 transmits this to the reception device 4. Through the above processing, transmission of stream data / data from the transmission device 3 to the reception device 4 is performed. The communication network may be any communication path as long as it is a wired or wireless communication network. Further, it may be a one-to-one connection form instead of a network form. Examples of the communication form include wireless LAN and IEEE1394.

  In the present embodiment, a system in which the transmission device 3 and the transmission-side communication device 1 are provided as separate devices is shown. However, the present invention is not limited to this. The configuration may be such that the function of the device 1 is provided. Similarly, the receiving device 4 may have a configuration in which the function of the receiving communication device 2 is provided.

  In the following description, an example in which video data encoded by MPEG2-TS as stream data is transmitted from the transmission device 3 to the reception device 4 will be described, but the type of data to be transmitted is particularly limited. It is not a thing. For example, the video data may be in other formats such as DVC, and the transmitted data may be other real-time data such as audio. Hereinafter, the MPEG2-TS packet is simply referred to as an MPEG packet.

(Configuration of transmission packet)
Here, a transmission packet sent from the transmission side communication apparatus 1 to the reception side communication apparatus 2 will be described. FIG. 4 shows a packet format of a transmission packet used in the present embodiment. As shown in the figure, the transmission packet has a structure in which a header, expiration date information, T1, MPEG packet (data block) 1, T2, MPEG packet 2,..., Tn, MPEG packet n are arranged in order from the head. It has become. The header is an area where information necessary for transmission on the network is stored. The expiration date information indicates the expiration date of the entire transmission packet. T1 to Tn are time information corresponding to MPEG packet 1 to MPEG packet n, respectively. These T1 to Tn indicate times when the corresponding MPEG packet is input from the transmission device 3 in the transmission side communication device 1. It is assumed that the transmission device 3 outputs each MPEG packet to the transmission side communication device 1 at the same time interval as the time interval at which each MPEG packet is generated. That is, each time interval from T1 to Tn is equal to the time interval at which each MPEG packet is generated.

(Configuration of transmitting communication device)
Next, the configuration of the transmission side communication apparatus 1 will be described below with reference to FIG. The transmission side communication device 1 includes a data input unit 11, a control unit 12, a communication I / F 13, and a storage unit 14.

  The data input unit 11 corresponds to an interface for inputting video data from the transmission device 3. This video data is input to the data input unit 11 in the MPEG2-TS packet format. The communication I / F 13 corresponds to an interface for performing communication with the receiving-side communication device 2. The transmission packet generated in the control unit 12 is transmitted to the receiving-side communication device 2 via the communication I / F 13.

  The control unit 12 is a block that performs control for generating a transmission packet based on the MPEG packet input from the transmission apparatus 3 and transmitting the transmission packet. The storage unit 14 is used as a work memory during transmission packet generation processing and transmission processing in the control unit 12. The storage unit 14 is configured by volatile storage means such as DRAM. The storage unit 14 may be configured by any storage means as long as the storage means can store data at least temporarily.

  The control unit 12 includes, as functional blocks, a data storage processing unit 21, a data time management unit (time management unit) 22, a transmission packet configuration unit (time limit setting unit, packet configuration unit) 23, and a transmission packet time management unit (expiration date management). Means) 24 and a transmission control unit 25. The storage unit 14 includes a data storage unit 31, a time information storage unit 32, and a transmission packet storage unit 33. In these data storage unit 31, time information storage unit 32, and transmission packet storage unit 33, memory control is performed by, for example, FIFO (first in first out).

  The data storage processing unit 21 performs a process of writing the MPEG packet input by the data input unit 11 into the data storage unit 31. The data time management unit 22 has a clock function and performs a process of writing the input time (T1 to Tn) when each MPEG packet is input in the data input unit 11 to the time information storage unit 32.

  The transmission packet time management unit 24 has a clock function, and is used when processing for adding expiration date information indicating the expiration date of the entire transmission packet to the transmission packet is performed by the transmission packet configuration unit 23.

  The transmission packet configuration unit 23 includes MPEG packet data (MPEG packet 1 to MPEG packet n) stored in the data storage unit 31 and input time (T1 to Tn) data stored in the time information storage unit 32. And a transmission packet is generated according to the format of the transmission packet described above. The expiration date information included in this transmission packet is acquired from the transmission packet time management unit 24. The transmission packet generated by the transmission packet configuration unit 23 is stored in the transmission packet storage unit 33.

  The transmission control unit 25 reads the transmission packet stored in the transmission packet storage unit 33 and controls transmission of the transmission packet from the communication I / F 13.

(Configuration of receiving side communication device)
Next, the configuration of the receiving communication device 2 will be described below with reference to FIG. The receiving side communication device 2 includes a communication I / F 41, a control unit 42, a data output unit 43, and a storage unit 44.

  The communication I / F 41 corresponds to an interface for performing communication with the transmission side communication device 1. The transmission packet received from the transmission side communication device 1 is input to the control unit 42 via the communication I / F 41. The data output unit 43 corresponds to an interface for outputting video data to the receiving device 4. This video data is output to the receiving device 4 in the form of an MPEG packet.

  The control unit 42 is a block that performs a control to restore the MPEG packet based on the transmission packet received from the transmission side communication device 1 and to output the MPEG packet. The storage unit 44 is used as a work memory when the control unit 42 performs MPEG packet restoration processing and output processing. The storage unit 44 is configured by volatile storage means such as DRAM. The storage unit 44 may be configured by any storage means as long as the storage means can store data at least temporarily.

  The control unit 42 includes, as functional blocks, a received packet processing unit (received packet processing unit) 51, a received packet time management unit (packet time management unit) 52, a video data processing unit 53, and a time adjustment unit (data block processing unit) 54. A data time management unit (data time management unit) 55 and an output control unit (data block processing unit) 56 are provided. The storage unit 44 includes a received packet storage unit 61, a data storage unit 62, and a time information storage unit 63. In the received packet storage unit 61, the data storage unit 62, and the time information storage unit 63, memory control is performed by, for example, FIFO (first in first out).

  The reception packet time management unit 52 has a clock function, and is used by the reception packet processing unit 51 to determine whether to discard the transmission packet based on the expiration date of the received transmission packet.

  The received packet processing unit 51 checks the header of the received transmission packet, and further checks the expiration date information to determine whether to discard the transmission packet. More specifically, the received packet processing unit 51 first calculates a corrected expiration date obtained by adding a predetermined time α to the expiration date of the received transmission packet. And this correction | amendment expiration date is compared with the time which the reception packet time management part 52 shows.

  In this comparison, when the time indicated by the reception packet time management unit 52 is earlier, the reception packet processing unit 51 determines that the reproduction time of the MPEG packet included in the transmission packet has already passed. That is, the received packet processing unit 51 discards the corresponding transmission packet when the header of the received transmission packet is abnormal and / or the expiration date is exceeded. The packet is discarded by not writing the transmission packet in the received packet storage unit 61. On the other hand, when there is no abnormality in the header of the received transmission packet and the expiration date has not exceeded, the reception packet processing unit 51 writes the transmission packet in the reception packet storage unit 61.

  Here, the time α is a fixed value, and is set in advance based on the transmission delay time and the number of retransmissions. When the time α is set to be relatively long, the transmission time delay from the transmission side communication device 1 to the reception side communication device 2 is allowed to be longer. That is, it is possible to perform retransmission processing more times when communication between the transmission-side communication device 1 and the reception-side communication device 2 fails, and high-quality transmission can be realized. However, if the time α is set to be relatively long, the amount of buffer required on the receiving side also increases, so that the memory capacity of the received packet storage unit 61 needs to be increased. Therefore, the value of time α is preferably set in consideration of the balance between communication quality and memory cost. In addition, it is good also as a structure which can change time (alpha) according to a condition.

  In the present embodiment, as described above, in the receiving-side communication device 2, the reception packet processing unit 51 calculates the corrected expiration date by adding the time α to the expiration date information. However, in the communication device 1 on the transmission side, when the transmission packet configuration unit 23 adds the expiration date information to the transmission packet, the corrected expiration date obtained by adding the time α may be added as the expiration date information. In this case, the reception packet processing unit 51 in the receiving-side communication device 2 does not perform the time α addition process, and obtains the expiration date (corrected expiration date) of the received transmission packet and the value indicated by the reception packet time management unit 52. A direct comparison is sufficient.

  The video data processing unit 53 reads the transmission packet stored in the received packet storage unit 61 when the correction expiration date of the transmission packet is reached, and reads time information (T1 to Tn) and video data (MPEG packet 1 to MPEG packet 1). The MPEG packet n) is extracted and written into the time information storage unit 63 and the data storage unit 62, respectively.

  The data time management unit 55 has a clock function, and is used in video data output timing control in the time adjustment unit 54.

  The time adjustment unit 54 acquires the time information (T1 to Tn) from the time information storage unit 63, and compares the time with the time indicated by the data time management unit 55, so that the output control unit 56 transfers to the data output unit 43. Processing for adjusting the timing of outputting the video data (MPEG packet 1 to MPEG packet n) is performed.

  The output control unit 56 reads the video data (MPEG packet 1 to MPEG packet n) to be output from the data storage unit 62 based on the timing adjustment by the time adjustment unit 54, and outputs the video data from the data output unit 43. To control.

(Processing flow in the sending communication device)
Next, the flow of processing in the transmission-side communication apparatus 1 will be described with reference to the flowchart shown in FIG.

  First, in step 1 (hereinafter referred to as S1), the data storage processing unit 21 determines whether or not an MPEG packet as video data is input to the data input unit 11. If NO in S1, that is, if it is determined that no MPEG packet has been input, the processing in S1 is repeated. That is, S1 corresponds to standby processing for MPEG packet input. If YES in S1, that is, if it is determined that an MPEG packet has been input, the process proceeds to S2.

  In S 2, the data storage processing unit 21 writes the MPEG packet input to the data input unit 11 into the data storage unit 31. At the same time, the data time management unit 22 acquires time information when the MPEG packet is input, and writes it in the time information storage unit 32.

  Next, in S <b> 3, the transmission packet configuration unit 23 determines whether the data storage processing unit 21 has written a predetermined number of MPEG packets in the data storage unit 31. If NO in S3, that is, if the number of MPEG packets written in the data storage unit 31 is less than the predetermined number, the process returns to S1. On the other hand, if YES in S3, that is, if the number of MPEG packets written in the data storage unit 31 exceeds a predetermined number, the process proceeds to S4.

  In S4, first, the transmission packet configuration unit 23 reads a predetermined number of MPEG packets from the data storage unit 31 and reads time information corresponding to each MPEG packet from the time information storage unit 32. Then, the transmission packet configuration unit 23 acquires time information from the transmission packet time management unit 24. Thereafter, in S5, the transmission packet configuration unit 23 regards the time information acquired from the transmission packet time management unit 24 as an expiration date, and generates a transmission packet based on the packet format shown in FIG. Then, the transmission packet configuration unit 23 writes the generated transmission packet in the transmission packet storage unit 33.

  Next, in S6, the transmission control unit 25 waits until the transmission time for transmitting the transmission packet is reached. When the transmission time is reached, in S7, the transmission control unit 25 reads the transmission packet from the transmission packet storage unit 33 and causes the communication I / F 13 to transmit the transmission packet.

(Processing flow in the receiving communication device)
Next, the flow of processing in the receiving-side communication device 2 will be described with reference to the flowchart shown in FIG.

  First, in S11, the received packet processing unit 51 determines whether or not a transmission packet is received in the communication I / F 41. If NO in S11, that is, if it is determined that a transmission packet has not been received, the processing in S11 is repeated. That is, S11 corresponds to reception packet reception standby processing. If YES in S11, that is, if it is determined that a transmission packet has been received, the process proceeds to S12.

  In S12, the received packet processing unit 51 first extracts expiration date information included in the received transmission packet. Then, the received packet processing unit 51 compares the corrected expiration time obtained by adding the predetermined time α to the expiration date and the time obtained from the received packet time management unit 52, and whether the expiration date has passed. Determine. If NO in S12, that is, if it is determined that the correction expiration date has already passed, the received packet processing unit 51 discards the entire transmission packet (S13). That is, the corresponding transmission packet is not written in the received packet storage unit 61.

  On the other hand, if YES in S12, that is, if it is determined that the expiration date has not yet passed, the received packet processing unit 51 writes the received transmission packet in the received packet storage unit 61 in S14.

  Next, in S <b> 15, the video data processing unit 53 determines whether or not it is time to output the transmission packet stored in the received packet storage unit 61. Here, the time when the transmission packet should be output corresponds to a correction expiration date that is a time obtained by adding a predetermined value α to the expiration date indicated by the expiration date information included in the transmission packet. After waiting for the time to be output in S15, when it is time to output, the process proceeds to S16.

  In S16, the video data processing unit 53 reads the transmission packet stored in the received packet storage unit 61, and extracts time information and MPEG packet corresponding to each MPEG packet. Then, the video data processing unit 53 writes the extracted time information in the time information storage unit 63 and the MPEG packet in the data storage unit 62, respectively.

  Next, in S <b> 17, the time adjustment unit 54 calculates a transmission time obtained by adding a predetermined time β to the time indicated in the time information corresponding to each MPEG packet written in the time information storage unit 63. Then, the time adjustment unit 54 waits for transmission of the corresponding MPEG packet until the time obtained from the data time management unit 55 reaches the transmission time. When the transmission time is reached, the output control unit 56 reads the corresponding MPEG packet from the data storage unit 62 based on the timing adjustment by the time adjustment unit 54 and the corresponding MPEG packet from the data output unit 43 to the receiving device 4 in S18. Output toward.

  Here, the time β is a fixed value, and is the time required from when the MPEG packet is input to the transmission side communication device 1 to when the MPEG packet is written to the data storage unit 62 at the reception side communication device 2. It is preset as a corresponding value. The value of the time β is set in consideration of a data processing delay, a transmission delay, a data processing delay time in the receiving side communication device 2, and the like.

  In the present embodiment, as described above, in the receiving side communication device 2, the time adjustment unit 54 calculates the transmission time by adding the time β to the time indicated in the time information corresponding to each MPEG packet. However, in the communication device 1 on the transmission side, when the data time management unit 22 sets time information corresponding to each MPEG packet, a transmission time obtained by adding the time β may be set as time information. In this case, the time adjustment unit 54 in the receiving side communication device 2 directly compares the time indicated by the time information corresponding to each MPEG packet with the value indicated by the data time management unit 55 without performing the addition process of the time β. You can do it.

  As described above, in the present embodiment, for example, even when a transmission delay occurs on the communication network and the transmission packet does not reach the receiving communication device 2 within a desired time, the receiving communication device 2 performs transmission. By referring to the expiration date information included in the packet, the transmission packet can be easily discarded.

  The data time management unit 22 in the transmission side communication device 1 and the data time management unit 55 in the reception side communication device 2 have the same time reference. In other words, the data time management unit 22 and the data time management unit 55 have a clock function that recognizes the same absolute time. The time reference deviation between the two needs to be smaller than the time interval deviation (output jitter) of each MPEG packet allowed at the time of reproduction of the MPEG packet. By realizing this, it is possible to perform high-quality real-time reproduction without causing frame defects and the like.

  Specifically, the data time management unit 22 and the data time management unit 55 are required to have an accuracy of about several hundred ns, depending on the performance of the MPEG2-TS decoder. If it becomes worse than this accuracy, there is a possibility that the reproduction of the video is disturbed even though the communication is normally performed.

  On the other hand, the transmission packet time management unit 24 in the transmission-side communication device 1 and the reception packet time management unit 52 in the reception-side communication device 2 still need to have the same time reference. The accuracy of the deviation does not need to be limited by the output jitter and may be looser. This is because the transmission packet time management unit 24 and the reception packet time management unit 52 need only have an accuracy for determining the necessity of discarding the transmission packet.

  In the present embodiment, the video data may be encrypted and transmitted. In this case, in the transmission packet, only the time information and the MPEG packet are encrypted without encrypting the expiration date information portion, so that the receiving-side communication apparatus 2 performs the transmission packet discarding process before the decryption. be able to. Therefore, in the transmission on the communication network, it is possible to discard the transmission packet even in a device that is in the middle of routing and cannot decode data.

(Embodiment 2)
Another embodiment of the present invention is described below with reference to the drawings. In addition, the same code | symbol is attached | subjected to the structure which has the function similar to the structure demonstrated in above-described embodiment, and the description is abbreviate | omitted.

  The communication network system according to the present embodiment has the same configuration as that described with reference to FIG. 3 in the first embodiment.

  FIG. 7 shows a schematic configuration of the transmitting communication device 1 according to the present embodiment, and FIG. 8 shows a schematic configuration of the receiving communication device 2 according to the present embodiment. As shown in the figure, in the present embodiment, in the configuration shown in the first embodiment, the control unit 12 of the transmission side communication device 1 does not include the transmission packet time management unit 24, and the reception side communication The control unit 42 of the device 2 is configured not to include the data time management unit 55. Other configurations are the same as those described in the first embodiment, and thus the description thereof is omitted. The format of the transmission packet used is also the same as the packet format shown in FIG.

  First, differences in the communication device 1 on the transmission side from the first embodiment will be described. The transmission packet configuration unit 23 includes MPEG packet data (MPEG packet 1 to MPEG packet n) stored in the data storage unit 31 and input time (T1 to Tn) data stored in the time information storage unit 32. And a transmission packet is generated in accordance with the transmission packet format described above. At this time, the transmission packet configuration unit 23 sets the expiration date information based on the value of T1 among the input times (T1 to Tn) stored in the time information storage unit 32.

  Note that as the expiration date indicated in the expiration date information, the value of T1 may be set as it is, or from when the MPEG packet is input to the data input unit 11 until the transmission packet forming unit 23 converts the packet into a transmission packet. A value obtained by adding a value corresponding to time to T1 may be set. Further, the expiration date may be set based on Tn instead of T1.

  Further, as described in the first embodiment, the corrected expiration date obtained by adding the time α described above to the expiration date set as described above may be added as the expiration date information.

  Next, differences in the receiving side communication device 2 from the first embodiment will be described. The time adjustment unit 54 acquires time information (T1 to Tn) from the time information storage unit 63, and compares the time with the time indicated by the reception packet time management unit 52, so that the output control unit 56 outputs the data output unit. 43 adjusts the timing of outputting video data (MPEG packet 1 to MPEG packet n).

  As described above, according to the present embodiment, the management of the expiration date information and the time information of the video data can be shared, so that the processing can be further simplified.

  In the present embodiment, the control unit 12 of the transmission side communication device 1 does not include the transmission packet time management unit 24, and the control unit 42 of the reception side communication device 2 includes the data time management unit 55. Although the control unit 12 of the transmission side communication device 1 does not include the transmission packet time management unit 24, the control unit 42 of the reception side communication device 2 includes the data time management unit 55. The configuration may be the same, or vice versa.

(Embodiment 3)
Still another embodiment of the present invention will be described below with reference to the drawings. In addition, the same code | symbol is attached | subjected to the structure which has the function similar to the structure demonstrated in each above-mentioned embodiment, and the description is abbreviate | omitted.

  The communication network system according to the present embodiment has the same configuration as that described with reference to FIG. 3 in the first embodiment.

(Configuration of transmission packet)
FIG. 9 shows a packet format of a transmission packet used in this embodiment. As shown in the figure, the transmission packet has a configuration in which a header, expiration date information, encryption information, T1, MPEG packet 1, T2, MPEG packet 2,..., Tn, MPEG packet n are arranged in order from the head. It has become. The encryption information corresponds to the encryption information described with reference to FIG. 16, that is, the encryption information field defined in DTCP Supplement E. The areas of MPEG packet 1 to MPEG packet n are encrypted by the encryption method indicated by the encryption information, while the areas of T1 to Tn corresponding to each MPEG packet are not encrypted. It has become. Other information included in the transmission packet is the same as that described with reference to FIG. 4 in the first embodiment, and a description thereof is omitted here. In the present embodiment, as described above, the transmission side communication apparatus 1 and the reception side are encrypted by encrypting the MPEG packet portion without encrypting the time information portion corresponding to each MPEG packet in the transmission packet. The reference time is corrected with the communication device 2 based on time information.

(Configuration of transmitting communication device)
Next, the configuration of the transmission side communication apparatus 1 according to the present embodiment will be described below with reference to FIG. As shown in the figure, in the communication apparatus 1 on the transmission side according to the present embodiment, the control unit 12 further includes an encryption unit (encryption unit) 26 and a time information insertion unit 27 in the configuration shown in the first embodiment. It is the composition equipped with. Other configurations are the same as those described in the first embodiment, and thus the description thereof is omitted.

  The encryption unit 26 reads data of a predetermined number of MPEG packets (MPEG packet 1 to MPEG packet n) from the data storage unit 31, and performs encryption processing by a predetermined method in a state where these are collected. That is, the MPEG packet 1 to the MPEG packet n are converted by the encryption unit 26 into one encrypted data.

  The time information insertion unit 27 divides the encrypted data encrypted by the encryption unit 26 into a predetermined length included in the encrypted data, and inputs the input time (T1 to Tn) into the time information storage unit 32, that is, Performs processing to insert time information data. That is, the time information insertion unit 27 performs a process of dividing the encrypted data into the number of MPEG packets included in the encrypted data, and inserting the time information data in front of each divided data. Since the length of one MPEG packet is 188 bytes, the time information insertion unit 27 inserts time information for each 188 bytes in the encrypted data. The encrypted data into which the time information is inserted is input to the transmission packet configuration unit 23, and the transmission packet configuration unit 23 configures the transmission packet shown in FIG. 9 based on this.

(Configuration of receiving side communication device)
Next, the configuration of the receiving communication device 2 according to the present embodiment will be described below with reference to FIG. As shown in the figure, the receiving side communication apparatus 2 according to the present embodiment has a configuration in which the control unit 42 further includes a time correction unit 57 and a decoding unit 58 in the configuration shown in the first embodiment. It has become. Other configurations are the same as those described in the first embodiment, and thus the description thereof is omitted.

  The time correction unit 57 corrects the clock function of the data time management unit 55 based on the time information included in the transmission packet for which the reception packet processing unit 51 has checked the header and the expiration date. The time correction unit 57 stores the transmission packet in the reception packet storage unit 61 after performing the correction process of the clock function.

  The decryption unit 58 receives the encrypted data of the MPEG packet extracted by the video data processing unit 53, performs a decryption process, and returns to a plurality of MPEG packets. The plurality of MPEG packets decoded by the decoding unit 58 are stored in the data storage unit 62.

(Processing flow in the sending communication device)
Next, the flow of processing in the transmission-side communication apparatus 1 according to the present embodiment will be described with reference to the flowchart shown in FIG.

  First, in S 21, the data storage processing unit 21 determines whether or not an MPEG packet as video data has been input to the data input unit 11. If NO in S21, that is, if it is determined that no MPEG packet has been input, the process of S21 is repeated. That is, S21 corresponds to an input standby process for MPEG packets. If YES in S21, that is, if it is determined that an MPEG packet has been input, the process proceeds to S22.

  In S 22, the data storage processing unit 21 writes the MPEG packet input to the data input unit 11 into the data storage unit 31. At the same time, the data time management unit 22 acquires time information when the MPEG packet is input, and writes it in the time information storage unit 32.

  Next, in S <b> 23, the encryption unit 26 determines whether a predetermined number of MPEG packets have been written in the data storage unit 31 by the data storage processing unit 21. If NO in S3, that is, if the number of MPEG packets written in the data storage unit 31 is less than the predetermined number, the process returns to S21. On the other hand, if YES in S23, that is, if the number of MPEG packets written in the data storage unit 31 exceeds a predetermined number, the process proceeds to S24.

  In S24, the encryption unit 26 reads a predetermined number of MPEG packets from the data storage unit 31, and performs encryption processing in a state in which these packets are collected. Thereby, one encrypted data including data of a plurality of MPEG packets is generated.

  Next, in S25, the time information insertion unit 27 divides the encrypted data generated by the encryption unit 26 into the number of MPEG packets included in the encrypted data, and the time information is inserted in front of each divided data. Perform processing to insert data. This time information is read from the time information storage unit 32. The inserted time information corresponds to each MPEG packet included in the encrypted data.

  Next, in S <b> 26, the transmission packet configuration unit 23 first receives encrypted data in which time information is inserted from the time information insertion unit 27. And the transmission packet structure part 23 considers the time information acquired from the transmission packet time management part 24 as an expiration date, and produces | generates a transmission packet based on the packet format shown in FIG. Then, the transmission packet configuration unit 23 writes the generated transmission packet in the transmission packet storage unit 33 (S27).

  Next, in S28, the transmission control unit 25 waits until the transmission time for transmitting the transmission packet is reached. When the transmission time is reached, in S29, the transmission control unit 25 reads the transmission packet from the transmission packet storage unit 33 and causes the communication I / F 13 to transmit the transmission packet.

(Processing flow in the receiving communication device)
Next, the flow of processing in the receiving communication device 2 according to the present embodiment will be described with reference to the flowchart shown in FIG.

  First, in S31, the reception packet processing unit 51 determines whether or not a transmission packet is received in the communication I / F 41. If NO in S31, that is, if it is determined that a transmission packet has not been received, the process of S31 is repeated. That is, S31 corresponds to standby processing for receiving a transmission packet. If YES in S31, that is, if it is determined that a transmission packet has been received, the process proceeds to S32.

  In S32, the received packet processing unit 51 first extracts expiration date information included in the received transmission packet. Then, the received packet processing unit 51 compares the corrected expiration time obtained by adding the predetermined time α to the expiration date and the time obtained from the received packet time management unit 52, and whether the expiration date has passed. Determine. If NO in S32, that is, if it is determined that the correction expiration date has already passed, the received packet processing unit 51 discards the entire transmission packet (S33). That is, the corresponding transmission packet is not written in the received packet storage unit 61.

  On the other hand, if YES in S32, that is, if it is determined that the expiration date has not yet passed, the received transmission packet is sent to the time correction unit 57. In S34, the time correction unit 57 extracts the time information included in the transmission packet, and in S35, corrects the clock function of the data time management unit 55 based on the time information. Since the time information is not encrypted, the time correction unit 57 can correct the time without performing the decryption process.

  Here, it is preferable that the time correction unit 57 basically performs correction based on time information (T1 in the above example) indicating the oldest time among a plurality of pieces of time information included in the transmission packet. This is because, for example, in the transmission side communication apparatus 1, it is considered that MPEG packets are input at a time interval slightly deviated from the timing of the actual MPEG packet generation time, for example, after T2. Note that although the value of T1 has a delay time shift in the transmission path, this shift is a substantially constant value in any MPEG packet. Therefore, a time lag occurs between the transmission side and the reception side, but since there is a constant lag, the output jitter of the MPEG packet is hardly affected. Also, this deviation is a very small value compared to the allowable output jitter of the MPEG packet.

  Thereafter, the time correction unit 57 writes the transmission packet in the received packet storage unit 61 (S36).

  Next, in S37, the video data processing unit 53 determines whether or not it is time to output the transmission packet stored in the received packet storage unit 61. Here, the time when the transmission packet should be output corresponds to a correction expiration date that is a time obtained by adding a predetermined value α to the expiration date indicated by the expiration date information included in the transmission packet. After waiting until the time to be output in S37, when it is time to output, the video data processing unit 53 reads the transmission packet stored in the received packet storage unit 61, and the process proceeds to S38.

  In S38, the decryption unit 58 receives the encrypted data from the video data processing unit 53, performs a decryption process, and returns to a plurality of MPEG packets. In S39, the decoding unit 58 stores a plurality of decoded MPEG packets in the data storage unit 62, and the video data processing unit 53 stores the time information extracted from the transmission packet in the time information storage unit 63. Stored.

  Next, in S40, the time adjustment unit 54 calculates a transmission time obtained by adding a predetermined time β to the time indicated by the time information corresponding to each MPEG packet written in the time information storage unit 63. Then, the time adjustment unit 54 waits for transmission of the corresponding MPEG packet until the time obtained from the data time management unit 55 reaches the transmission time. When the transmission time is reached, in S41, the output control unit 56 reads the corresponding MPEG packet from the data storage unit 62 based on the timing adjustment by the time adjustment unit 54, and sends the corresponding MPEG packet from the data output unit 43 to the receiving device 4. Output toward. It is to be noted that the description of the above time β and the transmission time obtained by adding the time β when the data time management unit 22 sets time information corresponding to each MPEG packet in the transmission side communication device 1 are time information. The configuration that can be set as is as described in the first embodiment.

  As described above, according to the present embodiment, the time lag correction process between the transmission-side communication device 1 and the reception-side communication device 2 is performed using the time information of the video data, and the video data is encrypted. It can be done.

  Each functional block provided in the control unit 12 and the control unit 42 may be configured by, for example, an LSI or may be configured by software. When configured in a software manner, it is realized by an arithmetic unit such as a CPU executing a program stored in a storage unit such as a ROM (Read Only Memory) or a RAM and controlling a communication unit such as an interface circuit. Can do. Therefore, the computer having these means can realize various functions and various processes of the control unit 12 and the control unit 42 of the present embodiment only by reading the recording medium storing the program and executing the program. it can. In addition, by recording the program on a removable recording medium, the various functions and various processes described above can be realized on an arbitrary computer.

  As the recording medium, a memory (not shown) such as a ROM may be used as a program medium for processing by the microcomputer, and a program reader is provided as an external storage device (not shown). It may be a program medium that can be read by inserting a recording medium therein.

  In any case, the stored program is preferably configured to be accessed and executed by the microprocessor. Furthermore, it is preferable that the program is read out, and the read program is downloaded to the program storage area of the microcomputer and the program is executed. It is assumed that the download program is stored in the main device in advance.

  In addition, if the system configuration is capable of connecting to a communication network including the Internet, the recording medium is preferably a recording medium that fluidly carries the program so as to download the program from the communication network.

  Further, when the program is downloaded from the communication network as described above, it is preferable that the download program is stored in the main device in advance or installed from another recording medium.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  The communication apparatus according to the present invention can be applied to, for example, a communication apparatus used for a transmission apparatus capable of transmitting stream data such as moving image data and other data to an external apparatus. Specifically, examples of the transmitting device include a device having a function of reproducing a moving image recorded as a digital code such as a DVD player, a DVD recorder, and an HDD recorder, and a broadcast receiving device such as a BS / CS tuner.

  The communication apparatus according to the present invention can be applied to a communication apparatus used for a reception apparatus that performs processing based on received stream data and other data, for example. Specifically, examples of the receiving device include a display device that displays moving image data as received stream data.

It is a block diagram which shows schematic structure of the transmission side communication apparatus which concerns on one Embodiment of this invention. It is a block diagram which shows schematic structure of the receiving side communication apparatus which concerns on one Embodiment of this invention. 1 is a block diagram showing a schematic configuration of a communication network system according to an embodiment of the present invention. It is a figure which shows the packet format of the transmission packet used in one Embodiment of this invention. It is a flowchart which shows the flow of the process in the said transmission side communication apparatus. It is a flowchart which shows the flow of the process in the said receiving side communication apparatus. It is a block diagram which shows schematic structure of the transmission side communication apparatus which concerns on other embodiment of this invention. It is a block diagram which shows schematic structure of the receiving side communication apparatus which concerns on other embodiment of this invention. It is a figure which shows the packet format of the transmission packet used in other embodiment of this invention. It is a block diagram which shows schematic structure of the transmission side communication apparatus which concerns on further another embodiment of this invention. It is a block diagram which shows schematic structure of the receiving side communication apparatus which concerns on further another embodiment of this invention. It is a flowchart which shows the flow of the process in the said transmission side communication apparatus. It is a flowchart which shows the flow of the process in the said receiving side communication apparatus. FIG. 4A is a diagram showing a time transition of packet generation on the conventional transmitting apparatus side, and FIG. 4B is a diagram showing a generated transmission packet. FIG. 4A is a diagram showing a transmission packet received by a conventional receiving device, and FIG. 4B is a diagram showing a time transition of packet reproduction on the receiving device side. It is a figure which shows the packet format of the packet encrypted by DTCP Supplement E.

Explanation of symbols

1 Transmission side communication device (communication device)
2 Receiving side communication device (communication device)
DESCRIPTION OF SYMBOLS 3 Transmission apparatus 4 Reception apparatus 11 Data input part 12 Control part 14 Storage part 21 Data storage process part 22 Data time management part (Time management means)
23 Transmission packet configuration unit (time limit setting means, packet configuration means)
24 Transmission packet time management unit (expiration date management means)
25 Transmission Control Unit 26 Encryption Unit (Encryption Unit)
27 Time information insertion unit 31 Data storage unit 32 Time information storage unit 33 Transmission packet storage unit 42 Control unit 43 Data output unit 44 Storage unit 51 Received packet processing unit (received packet processing means)
52 Received packet time management unit (packet time management means)
53 Video data processing unit 54 Time adjustment unit (data block processing means)
55 Data time management section (data time management means)
56 Output control unit (data block processing means)
57 Time correction unit 58 Decoding unit 61 Received packet storage unit 62 Data storage unit 63 Time information storage unit

Claims (13)

A communication device that transmits a transmission packet including a plurality of data blocks to a communication device connected via a communication path,
Time management means for generating time information associated with each of the data blocks;
Time limit setting means for generating time limit information relating to the time limit of the transmission packet;
A communication apparatus comprising: a packet composing unit that generates the transmission packet including the data block, the time information, and the expiration date information.   The said data block is a data block which comprises stream data, The said time management means produces | generates the said time information as information regarding the time when the applicable data block was produced | generated from the said stream data. The communication apparatus according to 1.   The communication apparatus according to claim 1, wherein the packet composing means generates the transmission packet in a state where the expiration date information is arranged at a predetermined position of the transmission packet. The time management means has a clock function used when generating the time information,
2. The communication apparatus according to claim 1, further comprising an expiration date management unit having a clock function used when the expiration date setting unit generates the expiration date information. The time management means has a clock function used when generating the time information,
2. The communication apparatus according to claim 1, wherein the time limit setting unit uses a clock function of the time management unit when generating the expiration date information. An encryption unit for performing encryption processing on the data block;
The packet construction unit generates the transmission packet including the data block encrypted by the encryption unit, and the time information and expiration date information not encrypted. The communication apparatus according to 1. A communication device that receives a transmission packet including a plurality of data blocks from a communication device according to any one of claims 1 to 6 via a communication path,
A communication apparatus comprising: a received packet processing unit that determines whether to discard the transmission packet based on expiration date information included in the received transmission packet. Data block processing means for performing processing on the data block included in the transmission block based on the time information included in the received transmission packet;
A packet time management unit having a clock function used when the received packet processing unit determines the expiration date information;
8. The communication apparatus according to claim 7, further comprising data time management means having a clock function used when the data block processing means performs processing on the data block. Data block processing means for performing processing on the data block included in the transmission block based on the time information included in the received transmission packet;
A packet time management means having a clock function used when the received packet processing means determines the expiration date information;
8. The communication apparatus according to claim 7, wherein the clock function of the packet time management means is used when the data block processing means performs processing on the data block.   9. The communication apparatus according to claim 8, further comprising time correction means for correcting a clock function of the data time management means based on the time information included in the received transmission packet.   A communication device according to any one of claims 1 to 6, and a communication device according to any one of claims 7 to 10 connected to the communication device via a communication path. A communication network system characterized by the above. A communication method in a communication apparatus for transmitting a transmission packet including a plurality of data blocks to a communication apparatus connected via a communication path,
Generating time information associated with each of the data blocks;
Generating expiration date information regarding the expiration date of the transmission packet;
And generating the transmission packet including the data block, the time information, and the expiration date information. A communication method in a communication device that receives a transmission packet including a plurality of data blocks from a communication device that executes the communication method according to claim 12 via a communication path,
A communication method comprising a step of determining whether to discard a transmission packet based on expiration date information included in the received transmission packet.

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