Switching method and IP retransmission device

Abstract

To provide stable content reproduction on a reproduction device with simple constitution while an IP retransmission device retransmitting contents is configured to be switched.SOLUTION: There is provided a switching method of an IP retransmission system comprising a plurality of IP retransmission devices which receive repeating IP packets including a broadcasted content and retransmit the content, included in the received repeating IP packets, in retransmitting IP packets, and the switching method includes the steps of: determining switching timing based upon information included in the repeating IP packets and changing in value according to transmission time of the repeating IP packets; and switching, at the switching timing, the retransmission of the content from an IP retransmission device of an in-operation system to an IP retransmission device of a standby system.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present disclosure relates to a switching method and an IP retransmission device.

Background Art

[0002] Conventionally, a system has been developed for retransmitting broadcast content by including it in IP packets.

[0003] For example, Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2020-10199) discloses the following IP retransmission device. That is, the IP retransmission device is an IP retransmission device used in an IP retransmission system that retransmits digital broadcast signals of a plurality of channels received from an antenna to a plurality of receivers via an IP multicast network. The IP retransmission device extracts SI information from the digital broadcast signal, stores the SI information in a packet in which an SI identification value is assigned to a part of the header information, and sends the packet to the IP multicast network together with the broadcast stream or separately from the broadcast stream.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the premises of a digital broadcast distributor such as a cable TV company, in addition to the operation system IP retransmission device, a spare IP retransmission device is often provided.

[0006] Here, when the retransmission by the operation system IP retransmission device is stopped for maintenance replacement or the like of the operation system IP retransmission device and the retransmission is switched to the spare IP retransmission device, it is desired to reproduce the content satisfactorily.

[0007] This disclosure was made to solve the above-mentioned problems, and its purpose is to provide a switching method and an IP retransmission device that enable stable content playback in a playback device with a simple configuration in a configuration in which an IP retransmission device that retransmits content can be switched. [Means for solving the problem]

[0008] The switching method of this disclosure is an IP retransmission system comprising a plurality of IP retransmission devices that receive relay IP packets containing broadcast content and include the content contained in the received relay IP packets in retransmission IP packets for retransmission, and a switching method for switching the retransmission of the content from the operational IP retransmission device to the standby IP retransmission device, comprising the steps of: causing the standby IP retransmission device to start receiving the same packets as the relay IP packets received by the operational IP retransmission device; matching the retransmission settings of the standby IP retransmission device to the retransmission settings of the operational IP retransmission device; determining a switching timing based on information contained in the relay IP packets, the value of which changes depending on the transmission time of the relay IP packets; and switching the retransmission of the content from the operational IP retransmission device to the standby IP retransmission device at the switching timing.

[0009] The IP retransmission device of this disclosure is an IP retransmission device in an IP retransmission system that receives a relay IP packet containing broadcast content, and includes the content contained in the received relay IP packet in a retransmission IP packet for retransmission, comprising: a receiving unit for receiving the relay IP packet; a transmitting unit for transmitting the retransmission IP packet; an acquisition unit for acquiring a switching timing which is the timing at which the transmission unit should switch the start and stop of transmitting the retransmission IP packet; and a switching unit that, based on information contained in the relay IP packet received by the receiving unit, whose value changes according to the transmission time of the relay IP packet, detects that the switching timing acquired by the acquisition unit has arrived, and switches the start and stop of transmitting the retransmission IP packet by the transmitting unit.

[0010] One aspect of this disclosure can be implemented not only as an IP retransmission device equipped with such characteristic processing, but also as an IP retransmission method with such characteristic processing as a step, as a program for causing a computer to execute such step, as a semiconductor integrated circuit that implements part or all of the IP retransmission device, or as an IP retransmission system including the IP retransmission device. [Effects of the Invention]

[0011] According to this disclosure, in a configuration in which an IP retransmission device that retransmits content can be switched, stable content playback in the playback device can be achieved with a simple configuration. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 is a diagram showing the configuration of an IP retransmission system according to an embodiment of the present disclosure. [Figure 2] Figure 2 shows the configuration of an IP retransmission device according to an embodiment of the present disclosure. [Figure 3]Figure 3 shows an example of an IP packet received by the IP receiving unit of an IP retransmission device according to an embodiment of the present disclosure. [Figure 4] Figure 4 shows an example of a switching process sequence in an IP retransmission system according to an embodiment of the present disclosure. [Figure 5] Figure 5 shows another example of the switching process sequence in the IP retransmission system according to the embodiment of this disclosure. [Figure 6] Figure 6 shows another example of the switching process sequence in the IP retransmission system according to the embodiment of this disclosure. [Figure 7] Figure 7 shows another example of the switching process sequence in the IP retransmission system according to the embodiment of this disclosure. [Modes for carrying out the invention]

[0013] First, the embodiments of this disclosure will be listed and explained.

[0014] (1) The switching method according to an embodiment of the present disclosure is an IP retransmission system comprising a plurality of IP retransmission devices that receive relay IP packets containing broadcast content and include the content contained in the received relay IP packets in retransmission IP packets for retransmission, and a switching method for switching the retransmission of the content from the operational IP retransmission device to the standby IP retransmission device, comprising the steps of: causing the standby IP retransmission device to start receiving the same packets as the relay IP packets received by the operational IP retransmission device; matching the retransmission settings of the standby IP retransmission device to the retransmission settings of the operational IP retransmission device; determining a switching timing based on information contained in the relay IP packets, the value of which changes depending on the transmission time of the relay IP packets; and switching the retransmission of the content from the operational IP retransmission device to the standby IP retransmission device at the switching timing.

[0015] In this way, by switching the retransmission of content from the active IP retransmission device to the standby IP retransmission device at a switching timing determined based on information whose value changes according to the transmission time of the relay IP packets, the timing of the content retransmission switch between the active and standby IP retransmission devices can be synchronized with a simple configuration. Therefore, when the IP retransmission device that retransmits content switches from the active system to the standby system, content playback can be performed seamlessly on the playback device. For example, even during the time when content should be retransmitted, i.e., when the IP retransmission device is operational, content playback can be performed seamlessly on the playback device when the IP retransmission device that retransmits content switches from the active system to the standby system. Thus, stable content playback on the playback device can be achieved with a simple configuration.

[0016] (2) The IP retransmission system further comprises a control device, and the switching method further includes the step that the control device creates a switching plan for the retransmission of the content in the active IP retransmission device and the standby IP retransmission device based on the monitoring results of the active IP retransmission device.

[0017] This method allows for the planned switching of content retransmissions, for example, based on the operating status of the operational IP retransmission equipment.

[0018] (3) The IP retransmission device according to an embodiment of the present disclosure is an IP retransmission device in an IP retransmission system that receives a relay IP packet including broadcast content, includes the content included in the received relay IP packet in a retransmission IP packet, and retransmits it, and includes a receiving unit that receives the relay IP packet, a transmitting unit that transmits the retransmission IP packet, an acquisition unit that acquires a switching timing that is a timing at which the transmission of the retransmission IP packet by the transmitting unit should be switched between start and stop, and a switching unit that switches between start and stop of the transmission of the retransmission IP packet by the transmitting unit when it is detected that the switching timing acquired by the acquisition unit has arrived based on information whose value changes according to the transmission time of the relay IP packet included in the relay IP packet received by the receiving unit.

[0019] In this way, by detecting that the switching timing has arrived based on information whose value changes according to the transmission time of the relay IP packet and switching between start and stop of the transmission of the retransmission IP packet, for example, in an operating IP retransmission device and a standby IP retransmission device, the timing for switching the retransmission of content can be adjusted with a simple configuration. Therefore, when the IP retransmission device that retransmits content switches from the operating system to the standby system, seamless content playback can be performed on the playback device. For example, even during the time period when content retransmission should be performed, that is, during the operation of the IP retransmission device, seamless content playback can be performed on the playback device when the IP retransmission device that retransmits content switches from the operating system to the standby system. Therefore, stable content playback in the playback device can be realized with a simple configuration.

[0020] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and their description will not be repeated. Also, at least a part of the embodiments described below may be arbitrarily combined.

[0021] [Configuration and Basic Operation] <IP Redelivery System> FIG. 1 is a diagram showing the configuration of an IP redelivery system according to an embodiment of the present disclosure. Referring to FIG. 1, the IP redelivery system 401 includes a plurality of IP redelivery devices 101, a plurality of IP redelivery devices 111, control devices 201 and 211, a head-end device 221, an EWS transmission device 251, and an SI transmission device 261. The IP redelivery devices 101 and 111, the control devices 201 and 211, the head-end device 221, the EWS transmission device 251, and the SI transmission device 261 are provided, for example, in the premises of a cable television station. The cable television station is capable of performing IP multicast broadcasts of a plurality of channels of local programming.

[0022] As an example, the IP redelivery system 401 includes N operational IP redelivery devices 101, one standby IP redelivery device 101, M operational IP redelivery devices 111, and one standby IP redelivery device 111. N and M are integers greater than or equal to 1, and they may be the same or different from each other. The standby IP redelivery device 101 is a backup device for the operational IP redelivery device 101. The standby IP redelivery device 111 is a backup device for the operational IP redelivery device 111. Note that the IP redelivery system 401 may be configured to include multiple standby IP redelivery devices 101 or multiple standby IP redelivery devices 111.

[0023] The headend device 221 transmits a stream containing multiple pieces of content from the local broadcast to the IP retransmission device 101. This content includes, for example, audio information, video information, PSI (Program Specific Information) information, SI information, and subtitle information. The headend device 221 generates multiple TS packets containing information that divides the content into multiple parts. The headend device 221 generates an IP packet Pcon in which, for example, seven TS packets are stored in the payload, and transmits the generated IP packet Pcon to each IP retransmission device 101. For example, the IP packet Pcon is an IPv4 packet. The IP packet Pcon is an example of a relay IP packet.

[0024] The IP retransmission device 101 receives an IP packet Pcon containing the broadcast content from the headend device 221 via a HUB (not shown), and retransmits the content contained in the received IP packet Pcon into an IP packet.

[0025] More specifically, each of the N operational IP retransmission devices 101 is assigned, for example, one different channel. The operational IP retransmission device 101 receives an IP packet Pcon containing content belonging to its assigned channel and obtains a TS packet from the received IP packet Pcon. The operational IP retransmission device 101 generates an IP packet Prt1 in which the seven obtained TS packets are stored in the payload, and transmits the generated IP packet Prt1 to the STB (Set Top Box) 301 at the subscriber's home via the IP network 151. For example, IP packet Prt1 is an IPv6 packet. IP packet Prt1 is an example of an IP packet for retransmission. In the IP network (CDN: Content Delivery Network) 151, for example, IP packets are transmitted according to the IP protocol.

[0026] Furthermore, the operational IP retransmission device 101 extracts TS packets containing SI information from the acquired TS packets, generates an IP packet Psi1 with the extracted TS packets stored in the payload, and transmits the generated IP packet Psi1 to the SI transmission device 261. For example, IP packet Psi1 is an IPv4 packet. IP packet Psi1 is an example of an IP packet for retransmission.

[0027] The IP retransmission device 111 receives broadcast waves from terrestrial digital broadcasting, BS digital broadcasting, or advanced BS digital broadcasting, and retransmits the content contained in the received broadcast waves in an IP packet. This content includes, for example, audio information, video information, PSI information, SI information, subtitle information, and EWS information.

[0028] More specifically, each of the M operational IP retransmission devices 111 is assigned, for example, one different channel. The operational IP retransmission devices 111 acquire content belonging to their assigned channel from the received broadcast wave and generate multiple TS packets containing information that the acquired content has been divided into multiple parts. The operational IP retransmission devices 111 generate IP packet Prt2 in which seven TS packets are stored in the payload and transmit the generated IP packet Prt2 to STB301 via the IP network 151. For example, IP packet Prt2 is an IPv6 packet.

[0029] Furthermore, the operational IP retransmission device 111 acquires EWS information and SI information from the received broadcast wave and generates IP packet Pews, in which a TS packet containing EWS information is stored in the payload, and IP packet Psi2, in which a TS packet containing SI information is stored in the payload. The operational IP retransmission device 111 transmits the generated IP packet Pews to the EWS transmission device 251 and transmits the generated IP packet Psi2 to the SI transmission device 261. For example, IP packets Pews and Psi2 are IPv4 packets.

[0030] The EWS transmission device 251 receives the IP packet Pew from the operation system's IP retransmission device 111, and transmits the IP packet PE generated by, for example, rewriting the header information of the received IP packet Pew to the STB 301 via the IP network 151. For example, the IP packet PE is an IPv6 packet.

[0031] The SI transmission device 261 receives the IP packets Psi1 and si2 from the operation system's IP retransmission device 101 and the operation system's IP retransmission device 111 respectively, and transmits the IP packet PS generated by, for example, rewriting the header information of the received IP packets Psi1 and si2 to the STB 301 via the IP network 151. For example, the IP packet PS is an IPv6 packet.

[0032] The control device 201 is connected to each IP retransmission device 101 via a HUB (not shown) for LAN (Local Area Network) connection. The control device 201 controls and monitors each IP retransmission device 101.

[0033] After starting up the IP retransmission device 101, the control device 201 transmits communication setting information Ccm indicating the IP address for communication with the control device 201, initial setting information Cin indicating whether the IP retransmission device 101 is in the operation system or the standby system, and retransmission setting information Crt regarding retransmission to the IP retransmission device 101.

[0034] The control device 211 is connected to each IP retransmission device 111 via a HUB (not shown) for LAN connection. The control device 211 controls and monitors each IP retransmission device 111.

[0035] <IP retransmission device> Figure 2 shows the configuration of an IP retransmission device according to an embodiment of the present disclosure. Referring to Figure 2, the IP retransmission device 101 comprises an IP receiving unit 11, a communication unit 12, a TS acquisition unit 13, a time information extraction unit 14, a processing unit 15, a PID (Packet ID) filter 16, IP transmission units 17A and 17B, and a storage unit 18. The IP receiving unit 11 is an example of a receiving unit. The IP transmission units 17A and 17B are examples of transmission units. The processing unit 15 is an example of an acquisition unit and also an example of a switching unit.

[0036] The communication unit 12 can send and receive various types of information with the control device 201 using IP packets.

[0037] The IP receiving unit 11 receives IP packets Pcon from the headend device 221 via a HUB (not shown). Each time the IP receiving unit 11 receives an IP packet Pcon from the headend device 221, it outputs the received IP packet Pcon to the TS acquisition unit 13.

[0038] Figure 3 shows an example of an IP packet received by the IP receiving unit of an IP retransmission device according to an embodiment of the present disclosure. Referring to Figure 3, the IP packet Pcon includes an IP header, a UDP (User Datagram Protocol) header, an RTP (Real-time Transport Protocol) header, and a payload.

[0039] The RTP header includes the following fields: Version, Padding, Extension, CSIC (Contributing Source Identifiers Count), Marker, Payload Type, Sequence Number, Timestamp, and SSRC (Synchronization Source).

[0040] For example, the timestamp field stores the clock count value Ccnt in the headend device 221. For example, the sequence number field stores the sequence value Cnmb, which indicates the transmission order of IP packets Pcon by the headend device 221. The count value Ccnt and the sequence value Cnmb are examples of transmission time information whose values ​​change depending on the transmission time of IP packets Pcon by the headend device 221.

[0041] Referring again to Figure 2, the TS acquisition unit 13 receives an IP packet Pcon from the IP reception unit 11, acquires seven TS packets from the payload of the received IP packet Pcon, and outputs them to the IP transmission unit 17A and the PID filter 16. The TS acquisition unit 13 also outputs the RTP information stored in the RTP header of the IP packet Pcon to the time information extraction unit 14.

[0042] For example, the time information extraction unit 14 receives RTP information from the TS acquisition unit 13, extracts the timestamp and sequence number from the received RTP information, and outputs the count value Ccnt indicated by the timestamp and the sequence value Cnmb indicated by the sequence number to the processing unit 15.

[0043] The processing unit 15 calculates a unit increase, which is the amount of increase in the sequence value Cnmb per unit time, based on a plurality of sequence values ​​Cnmb received from the time information extraction unit 14 over a predetermined period of time, and stores the calculated unit increase in the storage unit 18.

[0044] The PID filter 16 receives TS packets from the TS acquisition unit 13 and outputs TS packets containing SI information from the received TS packets to the IP transmission unit 17B. The SI information includes table information such as NIT (Network Information Table), SDT (Service Description Table), EIT (Event Information Table), BIT (Broadcaster Information Table), and CDT (Common Data Table). The PID filter 16 extracts TS packets containing SI information from the received TS packets by referring to the PID of the TS packets received from the TS acquisition unit 13. The PID filter 16 outputs the extracted TS packets to the IP transmission unit 17B.

[0045] The IP transmission unit 17A receives a TS packet from the TS acquisition unit 13 and generates an IP packet Prt1 in which seven TS packets are stored in the payload. The IP transmission unit 17A transmits the generated IP packet Prt1 to the IP network 151. The IP transmission unit 17A can switch between a transmit-on state, which enables the transmission of IP flows, and a transmit-off state, which does not enable the transmission of IP flows. For example, the IP transmission unit 17A is set to the transmit-off state when the IP retransmission device 101 is started up.

[0046] The IP transmission unit 17B receives TS packets from the PID filter 16 and generates an IP packet Psi1 in which seven TS packets are stored in the payload. The IP transmission unit 17B transmits the generated IP packet Psi1 to the SI transmission device 261. The IP transmission unit 17B can switch between a transmit-on state, which enables the transmission of IP flows, and a transmit-off state, which does not enable the transmission of IP flows. For example, the IP transmission unit 17B is set to the transmit-off state when the IP retransmission device 101 is started up.

[0047] (Initial settings) After the IP retransmission device 101 is started, the communication unit 12 receives communication configuration information Ccm from the control device 201 and communicates with the control device 201 using the IP address indicated by the received communication configuration information Ccm.

[0048] Furthermore, the communication unit 12 receives initial setup information Cin and retransmission setup information Crt from the control device 201. As described above, the initial setup information Cin indicates whether the IP retransmission device 101 is in the operational system or the standby system.

[0049] For example, the communication unit 12 of the operational IP retransmission device 101 receives reception setting information C1, transmission setting information C2, and SI extraction information C3 as retransmission setting information Crt. Reception setting information C1 is information indicating the IP address and port number of the IP packet Pcon that the operational IP retransmission device 101 should receive. Transmission setting information C2 is information indicating the IP address and port number of the IP packet Prt1 that the operational IP retransmission device 101 should transmit. SI extraction information C3 is information indicating the PID of the TS packet that the operational IP retransmission device 101 should store in the IP packet Psi1.

[0050] Furthermore, for example, the communication unit 12 of the standby IP retransmission device 101 receives correspondence information RE1, RE2, and RE3 as retransmission setting information Crt. Correspondence information RE1 is information showing the correspondence between the ID of the operational IP retransmission device 101 and the reception setting information C1 of the said IP retransmission device 101. Correspondence information RE2 is information showing the correspondence between the ID of the operational IP retransmission device 101 and the transmission setting information C2 of the said IP retransmission device 101. Correspondence information RE3 is information showing the correspondence between the ID of the operational IP retransmission device 101 and the SI extraction information C3 of the said IP retransmission device 101.

[0051] The communication unit 12 outputs the received initial setup information Cin and retransmission setup information Crt to the processing unit 15.

[0052] The processing unit 15 receives initial setup information Cin and retransmission setup information Crt from the communication unit 12, and stores the received initial setup information Cin and retransmission setup information Crt in the storage unit 18.

[0053] When the processing unit 15 receives initial setting information Cin indicating that the IP retransmission device 101 is in standby mode, it maintains the transmission-off state of the IP transmission units 17A and 17B. On the other hand, when the processing unit 15 receives initial setting information Cin indicating that the IP retransmission device 101 is in operation mode, it outputs an operation instruction to the IP transmission units 17A and 17B, thereby switching them to the transmission-on state.

[0054] The processing unit 15 in the operational IP retransmission device 101 outputs reception setting information C1 to the IP receiving unit 11. The processing unit 15 in the operational IP retransmission device 101 also outputs transmission setting information C2 to the IP transmitting units 17A and 17B. The processing unit 15 in the operational IP retransmission device 101 also outputs SI extraction information C3 to the PID filter 16.

[0055] In the operational IP retransmission device 101, the IP receiving unit 11 starts receiving IP packets Pcon from the headend device 221 according to the reception setting information C1 received from the processing unit 15. The IP transmitting units 17A and 17B start generating and transmitting IP packets Prt1 and Psi1 according to the transmission setting information C2 received from the processing unit 15. The PID filter 16 extracts TS packets containing the PID indicated by the SI extraction information C3 from the TS acquisition unit 13 according to the SI extraction information C3 received from the processing unit 15 and outputs them to the IP transmitting unit 17B.

[0056] In the standby IP retransmission device 101, the IP receiving unit 11 waits for the start of reception of IP packets Pcon. The IP transmitting units 17A and 17B also wait for the start of generation and transmission of IP packets Prt1 and Psi1.

[0057] (Example of switching method 1) For example, the control device 201 creates a switching plan for content retransmission in the active IP retransmission device 101 and the standby IP retransmission device 101 based on the monitoring results of the active IP retransmission device 101.

[0058] More specifically, the communication unit 12 in the operational IP retransmission device 101 periodically or irregularly transmits status information to the control device 201, indicating the operating status of the power supply unit, the operating status of the fan, and version information of the IP retransmission device 101.

[0059] Based on the status information received from each of the N operational IP retransmission devices 101, the control device 201 creates a switching plan that includes which of the N operational IP retransmission devices 101 should stop retransmitting content, and the start timing for initiating the switching process. Hereinafter, the IP retransmission device 101 that should stop retransmitting content will also be referred to as the "IP retransmission device 101 targeted for switching".

[0060] In the IP retransmission system 401, during the switching process, the standby IP retransmission device 101 is instructed to start receiving the same IP packet Pcon that the IP retransmission device 101 to be switched over receives. In addition, the settings for retransmission of the standby IP retransmission device 101 are matched to the settings for retransmission of the IP retransmission device 101 to be switched over.

[0061] More specifically, when the start timing arrives, the control device 201 sends a switching notification SW1 containing the ID of the IP retransmission device 101 to be switched to to the standby IP retransmission device 101.

[0062] When the processing unit 15 of the standby IP retransmission device 101 receives a switching notification SW1 from the control device 201 via the communication unit 12, it obtains reception setting information C1, transmission setting information C2, and SI extraction information C3 corresponding to the ID contained in the switching notification SW1 from the corresponding information RE1, RE2, and RE3 in the storage unit 18. The processing unit 15 outputs the obtained reception setting information C1 to the IP reception unit 11, the obtained transmission setting information C2 to the IP transmission units 17A and 17B, and the obtained SI extraction information C3 to the PID filter 16.

[0063] In the standby IP retransmission device 101, the IP receiving unit 11 starts receiving IP packets Pcon from the headend device 221 according to the reception setting information C1 received from the processing unit 15. That is, the IP receiving unit 11 starts receiving IP packets Pcon with the same content as the IP packets Pcon received by the IP retransmission device 101 that is to be switched over. The IP transmitting units 17A and 17B hold the transmission setting information C2 received from the processing unit 15 and wait for operation instructions from the processing unit 15. The PID filter 16 extracts TS packets containing the PID indicated by the SI extraction information C3 from the TS acquisition unit 13 according to the SI extraction information C3 received from the processing unit 15 and outputs them to the IP transmitting unit 17B.

[0064] Furthermore, the control device 201 transmits a switching notification SW2 to the IP retransmission device 101 that is to be switched.

[0065] When the processing unit 15 of the operational IP retransmission device 101 receives a switching notification SW2 from the control device 201 via the communication unit 12, it recognizes that the IP retransmission device 101 is the IP retransmission device 101 to be switched. The processing unit 15 then transmits timing information, including the latest count value Ccnt received from, for example, the time information extraction unit 14, to the control device 201 via the communication unit 12.

[0066] The control device 201 receives timing information from the IP retransmission device 101 to be switched over, and based on the received timing information, determines the switching timing to switch the content retransmission from the IP retransmission device 101 to the standby IP retransmission device 101.

[0067] For example, the control device 201 determines the switching timing based on the count value Ccnt included in the timing information. More specifically, the control device 201 holds frequency information indicating the clock frequency in the headend device 221. Based on the frequency information, the control device 201 calculates a count value SWcnt by adding, for example, the count value for 5 seconds to the count value Ccnt included in the timing information. The control device 201 determines the switching timing as the timing at which an IP packet Pcon, in which a count value Ccnt with the same value as SWcnt is stored in the timestamp field, arrives at the IP retransmission device 101.

[0068] The control device 201 generates switching information including the calculated count value SWcnt, and transmits the generated switching information to the IP retransmission device 101 to be switched and the standby IP retransmission device 101.

[0069] The processing unit 15 in the IP retransmission device 101 to be switched receives switching information from the control device 201 via the communication unit 12 and stores the received switching information in the storage unit 18.

[0070] Furthermore, the processing unit 15 in the standby IP retransmission device 101 receives switching information from the control device 201 via the communication unit 12 and stores the received switching information in the storage unit 18.

[0071] The processing unit 15 in the IP retransmission device 101 to be switched over and the processing unit 15 in the standby IP retransmission device 101 detect that the switching timing has arrived based on the count value Ccnt received from the time information extraction unit 14, and then switch the start and stop of transmission of IP packets Prt1 and Psi1 by the IP transmission units 17A and 17B.

[0072] More specifically, in the IP retransmission device 101 to be switched over, the processing unit 15 compares the received count value Ccnt with the count value SWcnt indicated by the switching information each time it receives a count value Ccnt from the time information extraction unit 14. If the received count value Ccnt matches the count value SWcnt, the processing unit 15 determines that the switching timing has arrived and outputs a stop command to the IP transmission units 17A and 17B, thereby switching the IP transmission units 17A and 17B to the transmission-off state. When the IP transmission units 17A and 17B switch to the transmission-off state, they stop generating and transmitting IP packets Prt1 and Psi1. The processing unit 15 also outputs a stop command to the IP reception unit 11. The IP reception unit 11 receives the stop command from the processing unit 15 and stops receiving IP packets Pcon from the headend device 221.

[0073] For example, in the IP retransmission device 101 that is to be switched over, the processing unit 15 sends a completion notification to the control device 201 via the communication unit 12 once the IP transmission units 17A and 17B have finished switching to the transmission-off state.

[0074] In the standby IP retransmission device 101, the processing unit 15 compares the count value indicated by the received timestamp with the count value SWcnt indicated by the switching information each time it receives a timestamp from the time information extraction unit 14. If the received count value Ccnt matches the count value SWcnt, the processing unit 15 determines that the switching timing has arrived and outputs an operation instruction to the IP transmission units 17A and 17B, thereby switching the IP transmission units 17A and 17B to the transmit-on state. When the IP transmission units 17A and 17B switch to the transmit-on state, they start generating and transmitting IP packets Prt1 and Psi1 according to the transmission setting information C2 they hold.

[0075] For example, in the standby IP retransmission device 101, once the IP transmission units 17A and 17B have finished switching to the transmission ON state, the processing unit 15 sends a completion notification to the control device 201 via the communication unit 12 indicating that the switch has been completed.

[0076] Furthermore, the processing unit 15 in the IP retransmission device 101 to be switched over may send a stop notification to the control device 201 in addition to the completion notification, indicating that the operational system has stopped. More specifically, when the switching of the IP transmission units 17A and 17B to the transmission-off state is completed, the processing unit 15 sends a completion notification to the control device 201 via the communication unit 12. Subsequently, when the reception of IP packets Pcon by the IP reception unit 11 stops and the IP retransmission device 101 to be switched over can be removed from the IP retransmission system 401, the processing unit 15 sends a stop notification to the control device 201 via the communication unit 12. This notifies the control device 201 that, in addition to the completion of the content retransmission switchover, it is possible to perform maintenance and replacement of the IP retransmission device 101 that has switched from the operational system to the standby system. In other words, the content retransmission switchover and the subsequent maintenance and replacement of the device can be handled separately.

[0077] Alternatively, instead of the processing unit 15 in the operational IP retransmission device 101, the processing unit 15 in the standby IP retransmission device 101 may transmit timing information to the control device 201 via the communication unit 12. More specifically, when the processing unit 15 in the standby IP retransmission device 101 receives a switching notification SW1 from the control device 201 via the communication unit 12, after the IP receiving unit 11 starts receiving IP packets Pcon, it transmits timing information, including the latest count value Ccnt received from, for example, the time information extraction unit 14, to the control device 201 via the communication unit 12. The control device 201 receives the timing information from the standby IP retransmission device 101 and determines the switching timing based on the count value Ccnt included in the received timing information.

[0078] (Example of switching method 2) In the above-described example 1 of the switching method, the control device 201 is configured to determine the switching timing based on the count value Ccnt of the IP packet Pcon, but it is not limited to this configuration. In example 2 of the switching method, the control device 201 determines the switching timing based on the sequence value Cnmb of the IP packet Pcon.

[0079] More specifically, when the processing unit 15 of the operational IP retransmission device 101 receives a switching notification SW2 from the control device 201 via the communication unit 12, it recognizes that the IP retransmission device 101 is the IP retransmission device 101 to be switched. The processing unit 15 then transmits timing information, including the latest sequence value Cnmb and unit increment amount received from, for example, the time information extraction unit 14, to the control device 201 via the communication unit 12.

[0080] The control device 201 receives timing information from the IP retransmission device 101 to be switched over, and calculates the increase in the sequence value Cnmb over a 5-second period, for example, based on the unit increase amount included in the received timing information. The control device 201 calculates the sequence value SWnmb by adding the calculated increase amount to the sequence value Cnmb included in the timing information. The control device 201 determines the timing at which an IP packet Pcon arrives at the IP retransmission device 101, in which the sequence value Cnmb has the same value as the sequence value SWnmb stored in the sequence number field, as the switching timing.

[0081] The control device 201 generates switching information including the calculated sequence value SWnmb, and transmits the generated switching information to the IP retransmission device 101 to be switched and the standby IP retransmission device 101.

[0082] The processing unit 15 in the IP retransmission device 101 to be switched receives switching information from the control device 201 via the communication unit 12 and stores the received switching information in the storage unit 18.

[0083] Furthermore, the processing unit 15 in the standby IP retransmission device 101 receives switching information from the control device 201 via the communication unit 12 and stores the received switching information in the storage unit 18.

[0084] The processing unit 15 in the IP retransmission device 101 to be switched over and the processing unit 15 in the standby IP retransmission device 101 detect that the switching timing has arrived based on the sequence value Cnmb received from the time information extraction unit 14, and then switch the start and stop of transmission of IP packets Prt1 and Psi1 by the IP transmission units 17A and 17B.

[0085] More specifically, in the IP retransmission device 101 to be switched over, the processing unit 15 compares the received sequence value Cnmb with the sequence value SWnmb indicated by the switching information each time it receives a sequence value Cnmb from the time information extraction unit 14. If the received sequence value Cnmb matches the sequence value SWnmb, the processing unit 15 determines that the switching timing has arrived and outputs a stop command to the IP transmission units 17A and 17B, thereby switching the IP transmission units 17A and 17B to the transmission-off state. When the IP transmission units 17A and 17B switch to the transmission-off state, they stop generating and transmitting IP packets Prt1 and Psi1. The processing unit 15 also outputs a stop command to the IP reception unit 11. The IP reception unit 11 receives the stop command from the processing unit 15 and stops receiving IP packets Pcon from the headend device 221.

[0086] For example, in the IP retransmission device 101 that is to be switched over, the processing unit 15 sends a completion notification to the control device 201 via the communication unit 12 once the IP transmission units 17A and 17B have finished switching to the transmission-off state.

[0087] In the standby IP retransmission device 101, the processing unit 15 compares the received sequence value Cnmb with the sequence value SWnmb indicated by the switching information each time it receives a sequence value Cnmb from the time information extraction unit 14. If the received sequence value Cnmb matches the sequence value SWnmb, the processing unit 15 determines that the switching timing has arrived and outputs an operation instruction to the IP transmission units 17A and 17B, thereby switching the IP transmission units 17A and 17B to the transmit-on state. Once the IP transmission units 17A and 17B are switched to the transmit-on state, they start generating and transmitting IP packets Prt1 and Psi1 according to the transmission setting information C2 they hold.

[0088] For example, in the standby IP retransmission device 101, once the IP transmission units 17A and 17B have finished switching to the transmission ON state, the processing unit 15 sends a completion notification to the control device 201 via the communication unit 12 indicating that the switch has been completed.

[0089] Alternatively, instead of the processing unit 15 in the operational IP retransmission device 101, the processing unit 15 in the standby IP retransmission device 101 may transmit timing information to the control device 201 via the communication unit 12. More specifically, when the processing unit 15 in the standby IP retransmission device 101 receives a switching notification SW1 from the control device 201 via the communication unit 12, after the IP receiving unit 11 starts receiving IP packets Pcon, it transmits timing information, including the latest sequence value Cnmb received from, for example, the time information extraction unit 14, to the control device 201 via the communication unit 12. The control device 201 receives the timing information from the standby IP retransmission device 101 and determines the switching timing based on the sequence value Cnmb included in the received timing information.

[0090] (Example of switching method 3) In the above-described examples 1 and 2 of the switching method, the control device 201 is configured to determine the switching timing, but this is not the only configuration. In example 3 of the switching method, the processing unit 15 in the IP retransmission device 101 determines the switching timing instead of the control device 201.

[0091] More specifically, when the processing unit 15 in the operational IP retransmission device 101 receives a switching notification SW2 from the control device 201 via the communication unit 12, it recognizes that the IP retransmission device 101 is the IP retransmission device 101 to be switched over. The processing unit 15 then calculates a count value SWcnt by adding, for example, the count value for 5 seconds to the latest count value Ccnt received from the time information extraction unit 14. The processing unit 15 determines the timing at which an IP packet Pcon, in which a count value Ccnt with the same value as the count value SWcnt is stored in the timestamp field, arrives at the IP retransmission device 101 as the switching timing.

[0092] The processing unit 15 in the operational IP retransmission device 101 generates calculation information including the calculated count value SWcnt, and transmits the generated calculation information to the control device 201 via the communication unit 12.

[0093] The control device 201 receives calculation information from the IP retransmission device 101 to be switched over, and obtains the count value SWcnt from the received calculation information. The control device 201 generates switching information including the count value SWcnt, and transmits the generated switching information to the standby IP retransmission device 101.

[0094] Alternatively, instead of the processing unit 15 in the operational IP retransmission device 101, the processing unit 15 in the standby IP retransmission device 101 may determine the switching timing. More specifically, when the processing unit 15 in the standby IP retransmission device 101 receives a switching notification SW1 from the control device 201 via the communication unit 12, it calculates a count value SWcnt. The processing unit 15 determines the timing at which an IP packet Pcon arrives at the IP retransmission device 101, in which a count value Ccnt with the same value as the count value SWcnt is stored in the timestamp field, as the switching timing.

[0095] Furthermore, the processing unit 15 in the operational IP retransmission device 101 or the processing unit 15 in the standby IP retransmission device 101 may be configured to generate calculated information including a sequence value SWnmb instead of a count value SWcnt, and to transmit the generated calculated information to the control device 201 via the communication unit 12.

[0096] (Example of switching method 4) In Example 1 of the switching method described above, the control device 201 is configured to create the switching plan, but this is not the only configuration. In Example 4 of the switching method, instead of the control device 201 creating the switching plan, one of the devices in the IP retransmission system 401 receives a switching instruction, including the switching plan, from the administrator of the IP retransmission system 401.

[0097] More specifically, the IP retransmission system 401 further comprises a console device (not shown). For example, the control device 201 receives switching instructions, including a switching plan, from the administrator of the IP retransmission system 401 via the console device.

[0098] When the start timing indicated by the received switching plan arrives, the control device 201 sends a switching notification SW1 to the standby IP retransmission device 101 and a switching notification SW2 to the IP retransmission device 101 to be switched over.

[0099] Alternatively, instead of the control device 201, the IP retransmission device 101 may be configured to receive switching instructions, including the switching plan, from the administrator of the IP retransmission system 401 via a console device. For example, the standby IP retransmission device 101 or the IP retransmission device 101 to be switched receives switching instructions from the administrator of the IP retransmission system 401 via a console device. The processing unit 15 in the IP retransmission device 101 receives the switching instructions and transmits the received instructions to the control device 201 via the communication unit 12.

[0100] (Example of switching method 5) In the above-described examples 1 to 4 of the switching method, the configuration is assumed to be one in which the switching process is performed using the control device 201, but this is not the only configuration. In example 5 of the switching method, the switching process is performed without using the control device 201. In this case, for example, the operational IP retransmission device 101 and the standby IP retransmission device 101 are connected to each other via a HUB (not shown) on the LAN.

[0101] For example, the IP retransmission device 101 to be switched over receives a switching instruction, including the switching plan, from the administrator of the IP retransmission system 401 via a console device.

[0102] When the start timing indicated in the received switching plan arrives, the processing unit 15 of the IP retransmission device 101 to be switched transmits a switching notification SW1, which includes the ID of the IP retransmission device 101, to the standby IP retransmission device 101.

[0103] Furthermore, the processing unit 15 in the IP retransmission device 101 to be switched determines the switching timing based on the count value Ccnt or the sequence value Cnmb. The processing unit 15 then generates switching information including the count value SWcnt or the sequence value SWnmb, and transmits the generated switching information to the standby IP retransmission device 101 via the communication unit 12.

[0104] In addition, the IP retransmission system 401 may perform the switching process by combining some or all of the examples 1 to 5 of the switching methods described above.

[0105] [Operation Flow] Each device in the IP retransmission system according to the embodiments of this disclosure comprises a computer including memory, and the arithmetic processing unit such as the CPU in the computer reads and executes a program from the memory that includes some or all of the steps in the following flowchart and sequence. The programs for each of these devices can be installed externally. The programs for each of these devices are distributed either stored on a recording medium or via a communication line.

[0106] Figure 4 is a diagram showing an example of a switching process sequence in an IP retransmission system according to an embodiment of the present disclosure. In Figure 4, an example of an IP retransmission device 101 is shown, including the operational IP retransmission devices 101A and 101B and the standby IP retransmission device 101C. Figure 4 shows the sequence of Example 1 of the switching method described above.

[0107] Referring to Figure 4, first, after the IP retransmission devices 101A, 101B, and 101C are started up, the control device 201 sends communication setting information Ccm, initial setting information Cin, and retransmission setting information Crt to the IP retransmission devices 101A, 101B, and 101C (step S11).

[0108] Next, the IP retransmission devices 101A and 101B switch the IP transmission units 17A and 17B to the transmit-on state and begin generating and transmitting IP packets Prt1 and Psi1 (step S12).

[0109] Next, the control device 201 creates a switching plan based on the operating status of the power supply units, the operating status of the fans, and version information in the IP retransmission devices 101A and 101B. As an example, the control device 201 creates a switching plan indicating that the retransmission of content by the IP retransmission device 101A should be stopped (step S13).

[0110] Next, the IP retransmission system 401 causes the IP retransmission device 101C to begin receiving the same IP packet Pcon that the IP retransmission device 101A, which is the target of the switchover, receives. It also adjusts the retransmission settings of the IP retransmission device 101C to match the retransmission settings of the IP retransmission device 101A. More specifically, when the timing for the start of the switchover process arrives, the control device 201 sends a switchover notification SW1 containing the ID of the IP retransmission device 101A to the IP retransmission device 101C (step S14).

[0111] Next, the IP retransmission device 101C obtains the reception setting information C1, transmission setting information C2, and SI extraction information C3 corresponding to the ID of the IP retransmission device 101A, and starts receiving IP packets Pcon from the headend device 221 according to the reception setting information C1 (step S15).

[0112] Next, the control device 201 transmits a switching notification SW2 to the IP retransmission device 101A (step S16).

[0113] Next, after receiving the switching notification SW2 from the control device 201, the IP retransmission device 101A sends timing information to the control device 201, including the latest count value Ccnt stored in the timestamp field of the IP packet Pcon received from the headend device 221 (step S17).

[0114] Next, the control device 201 determines the switching timing based on the count value Ccnt included in the timing information received from the IP retransmission device 101A. More specifically, the control device 201 calculates a count value SWcnt by adding the count value for 5 seconds to the count value Ccnt (step S18).

[0115] Next, the control device 201 transmits switching information, including the count value SWcnt, to the IP retransmission devices 101A and 101C (step S19).

[0116] Next, at the switching timing determined by the control device 201, the retransmission of content is switched from IP retransmission device 101A to IP retransmission device 101C. More specifically, when the count value Ccnt stored in the timestamp field of the received IP packet Pcon matches the count value SWcnt, IP retransmission device 101A determines that the switching timing has arrived, switches the IP transmission units 17A and 17B to the transmission off state, and stops the generation and transmission of IP packets Prt1 and Psi1 (step S20).

[0117] Furthermore, when the IP retransmission device 101C determines that the switching timing has arrived when the count value Ccnt stored in the timestamp field of the received IP packet Pcon matches the count value SWcnt, it switches the IP transmission units 17A and 17B to the transmit ON state and starts generating and transmitting IP packets Prt1 and Psi1 (step S21).

[0118] In step S17, the IP retransmission device 101A may transmit timing information to the control device 201, including the latest sequence value Cnmb and unit increment amount stored in the sequence number field of the IP packet Pcon received from the headend device 221. In this case, in step S18, the control device 201 determines the switching timing based on the sequence value Cnmb included in the timing information received from the IP retransmission device 101A. More specifically, the control device 201 calculates the sequence value SWnmb by adding the increment amount of the sequence value Cnmb over a 5-second period to the sequence value Cnmb. Then, in step S19, the control device 201 transmits the switching information including the sequence value SWnmb to the IP retransmission devices 101A and 101C.

[0119] Figure 5 shows another example of the switching process sequence in the IP retransmission system according to the embodiment of this disclosure. Figure 5 shows the sequence of Example 3 of the switching method described above.

[0120] Referring to Figure 5, first, the control device 201 and the IP retransmission devices 101A, 101B, and 101C perform the same processing as steps S11 to S16 in the sequence shown in Figure 4 as the processing from step S31 to step S36.

[0121] Next, after receiving the switching notification SW2 from the control device 201, the IP retransmission device 101A determines the switching timing based on the latest count value Ccnt stored in the timestamp field of the IP packet Pcon received from the headend device 221. More specifically, the IP retransmission device 101A calculates a count value SWcnt by adding the count value for 5 seconds to the count value Ccnt (step S37).

[0122] Next, the IP retransmission device 101A transmits calculated information, including the count value SWcnt, to the control device 201 (step S38).

[0123] Next, the control device 201 obtains the count value SWcnt from the calculation information received from the IP retransmission device 101A and transmits switching information including the count value SWcnt to the IP retransmission device 101C (step S39).

[0124] Next, at the switching timing determined by the IP retransmission device 101A, the retransmission of content is switched from the IP retransmission device 101A to the IP retransmission device 101C. More specifically, when the count value Ccnt stored in the timestamp field of the received IP packet Pcon matches the calculated count value SWcnt, the IP retransmission device 101A determines that the switching timing has arrived and switches the IP transmission units 17A and 17B to the transmission off state, stopping the generation and transmission of IP packets Prt1 and Psi1 (step S40).

[0125] Furthermore, when the IP retransmission device 101C determines that the switching timing has arrived when the count value Ccnt stored in the timestamp field of the received IP packet Pcon matches the count value SWcnt, it switches the IP transmission units 17A and 17B to the transmit ON state and starts generating and transmitting IP packets Prt1 and Psi1 (step S41).

[0126] Figure 6 shows another example of the switching process sequence in the IP retransmission system according to the embodiment of the present disclosure. Figure 6 shows the sequence of Example 4 of the switching method described above.

[0127] Referring to Figure 6, first, the control device 201 and the IP retransmission devices 101A, 101B, and 101C perform the same processing as steps S11 to S12 in the sequence shown in Figure 4 as the processing from step S51 to step S52.

[0128] Next, the control device 201 receives a switching instruction, including a switching plan, from the administrator of the IP retransmission system 401 via the console device (step S53).

[0129] Next, the control device 201 and the IP retransmission devices 101A and 101C perform the same processing as steps S14 to S21 in the sequence shown in Figure 4 as the processing from step S54 to step S61.

[0130] Figure 7 shows another example of the switching process sequence in the IP retransmission system according to the embodiment of the present disclosure. In Figure 7, an example of the IP retransmission device 101 is shown, consisting of an operational IP retransmission device 101A and a standby IP retransmission device 101C. Figure 7 shows the sequence of Example 5 of the switching method described above.

[0131] Referring to Figure 7, first, the control device 201 and the IP retransmission devices 101A and 101C perform the same processing as steps S11 and S12 in the sequence shown in Figure 4 as the processing from step S71 to step S72.

[0132] Next, the IP retransmission device 101A receives a switching instruction, including a switching plan, from the administrator of the IP retransmission system 401 via the console device (step S73).

[0133] Next, when the start timing indicated in the accepted switching plan arrives, the IP retransmission device 101A sends a switching notification SW1 containing the ID of IP retransmission device 101A to the IP retransmission device 101C (step S74).

[0134] Next, the IP retransmission device 101C obtains the reception setting information C1, transmission setting information C2, and SI extraction information C3 corresponding to the ID of the IP retransmission device 101A, and starts receiving IP packets Pcon from the headend device 221 according to the reception setting information C1 (step S75).

[0135] Next, the IP retransmission device 101A determines the switching timing based on the latest count value Ccnt stored in the timestamp field of the IP packet Pcon received from the headend device 221. More specifically, the IP retransmission device 101A calculates a count value SWcnt by adding the count value for 5 seconds to the count value Ccnt (step S76).

[0136] Next, the IP retransmission device 101A transmits switching information, including the count value SWcnt, to the IP retransmission device 101C (step S77).

[0137] Next, at the switching timing determined by the IP retransmission device 101A, the retransmission of content is switched from the IP retransmission device 101A to the IP retransmission device 101C. More specifically, when the count value Ccnt stored in the timestamp field of the received IP packet Pcon matches the calculated count value SWcnt, the IP retransmission device 101A determines that the switching timing has arrived, switches the IP transmission units 17A and 17B to the transmission off state, and stops the generation and transmission of IP packets Prt1 and Psi1 (step S78).

[0138] Furthermore, when the IP retransmission device 101C determines that the switching timing has arrived when the count value Ccnt stored in the timestamp field of the received IP packet Pcon matches the count value SWcnt, it switches the IP transmission units 17A and 17B to the transmit-on state and starts generating and transmitting IP packets Prt1 and Psi1 (step S79).

[0139] Incidentally, in a configuration where the IP retransmission device that retransmits content can be switched, there is a need for a technology that can achieve stable content playback on the playback device with a simple configuration.

[0140] In contrast, the switching method according to the embodiment of this disclosure is a switching method for switching the retransmission of content from the active IP retransmission device 101 to the standby IP retransmission device 101 in an IP retransmission system 401 that includes a plurality of IP retransmission devices 101 that receive IP packets Pcon containing broadcast content and retransmit the content contained in the received IP packets Pcon into IP packets Prt1,Psi1. In this switching method, first, the standby IP retransmission device 101 is made to start receiving the same packets as the IP packets Pcon received by the active IP retransmission device 101. Next, the settings for retransmission of the standby IP retransmission device 101 are matched to the settings for retransmission of the active IP retransmission device 101. The switching timing is determined based on information contained in the IP packets Pcon, whose value changes depending on the transmission time of the IP packets Pcon. Next, at the switching timing, the retransmission of content is switched from the active IP retransmission device 101 to the standby IP retransmission device 101.

[0141] In this way, by switching the retransmission of content from the active IP retransmission device to the standby IP retransmission device at a switching timing determined based on information whose value changes according to the transmission time of the IP packet Pcon, the timing of the content retransmission switch between the active and standby IP retransmission devices can be synchronized with a simple configuration. Therefore, when the IP retransmission device that retransmits content switches from the active to the standby system, content playback can be performed seamlessly on the playback device. Furthermore, even during the time when content retransmission should be performed, i.e., when the IP retransmission device is operational, content playback can be performed seamlessly on the playback device when the IP retransmission device that retransmits content switches from the active to the standby system. Thus, stable content playback on the playback device can be achieved with a simple configuration.

[0142] Furthermore, by determining the switching timing using information whose values ​​change depending on the transmission time of the IP packet Pcon, such as the count value Ccnt and sequence value Cnmb stored in the RTP header of the IP packet Pcon, the operational and standby IP retransmission devices can detect the arrival of the timing to switch content retransmission without analyzing the TS packets stored in the payload of the IP packet Pcon.

[0143] The embodiments described above should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than the above description, and all modifications within the meaning and scope equivalent to the claims are intended to be included.

[0144] The above description includes the following features. [Note 1] In an IP retransmission system comprising multiple IP retransmission devices that receive relay IP packets containing broadcast content and retransmit the content contained in the received relay IP packets in retransmission IP packets, a switching method for switching the retransmission of the content from the operational IP retransmission device to the standby IP retransmission device, The steps include causing the IP retransmission device in the operational system to start receiving the same relay IP packets that the IP retransmission device in the operational system receives, The steps include: matching the retransmission settings of the standby IP retransmission device with the retransmission settings of the operational IP retransmission device; A step of determining the switching timing based on information contained in the relay IP packet, the value of which changes depending on the transmission time of the relay IP packet, The switching timing includes the step of switching the retransmission of the content from the operational IP retransmission device to the standby IP retransmission device, A switching method in which, in the step of determining the switching timing, the switching timing is determined based on the information stored in the RTP header of the relay IP packet. [Explanation of Symbols]

[0145] 11 IP receiving unit 12 Communications Department 13 TS Acquisition Department 14-hour information extraction unit 15 Processing Unit 16 PID filters 17A,17B IP transmitter 18 Memory section 101 IP retransmission device 111 IP retransmission device 151 IP network 201 Control device 211 Control device 221 Headend device 251 EWS sending device 261 SI sending device 301 STB 401 IP retransmission system

Claims

1. In an IP retransmission system comprising multiple IP retransmission devices that receive relay IP packets containing broadcast content and retransmit the content contained in the received relay IP packets by including it in retransmission IP packets, a switching method for switching the retransmission of the content from the operational IP retransmission device to the standby IP retransmission device, The steps include causing the standby IP retransmission device to begin receiving the same relay IP packets that the operational IP retransmission device receives, The steps include: matching the retransmission settings of the standby IP retransmission device with the retransmission settings of the operational IP retransmission device; The steps include determining the switching timing based on transmission time information included in the relay IP packet, which changes in value depending on the transmission time of the relay IP packet, The switching timing includes the step of switching the retransmission of the content from the operational IP retransmission device to the standby IP retransmission device, The IP retransmission device acquires a TS packet from the payload of the relay IP packet, and transmits the retransmission IP packet in which the acquired TS packet is stored in the payload. A switching method in which the aforementioned transmission time information is included in the RTP header of the relay IP packet.

2. The IP retransmission system further comprises a control device, The aforementioned switching method further includes, The switching method according to claim 1, wherein the control device includes the step of creating a switching plan for the retransmission of the content in the IP retransmission device in the operational system and the IP retransmission device in the standby system, based on the monitoring results of the IP retransmission device in the operational system.

3. The switching method according to claim 1 or 2, wherein in the step of determining the switching timing, the timing at which the relay IP packet containing the transmission time information that satisfies the switching conditions arrives at the IP retransmission device is determined as the switching timing.

4. An IP retransmission device in an IP retransmission system that receives a relay IP packet containing broadcast content, and includes the content contained in the received relay IP packet in a retransmission IP packet for retransmission, A receiving unit that receives the aforementioned relay IP packets, A transmitting unit that transmits the aforementioned IP packets for retransmission, An acquisition unit that acquires a switching timing which is the timing at which the transmission unit should switch between starting and stopping the transmission of the retransmission IP packets, The receiving unit receives the relay IP packet and, based on transmission time information that changes in value according to the transmission time of the relay IP packet, detects that the switching timing acquired by the acquisition unit has arrived, and includes a switching unit that switches the start and stop of the transmission of the retransmission IP packet by the transmitting unit. The aforementioned IP retransmission device further, A TS packet acquisition unit acquires TS packets from the payload of the relay IP packets received by the receiving unit, The system comprises a generation unit that generates the retransmission IP packet in which the TS packet acquired by the TS packet acquisition unit is stored in the payload, The aforementioned transmission time information is included in the RTP header of the relay IP packet, according to the IP retransmission device.

5. The acquisition unit acquires the switching timing, which is the timing at which the relay IP packet containing the transmission time information that satisfies the switching conditions arrives at the IP retransmission device. The IP retransmission device according to claim 4, wherein the switching unit compares the switching condition with the transmission time information contained in the relay IP packet received by the receiving unit, and if the result of the comparison between the switching condition and the transmission time information satisfies a predetermined condition, the start and stop of the transmission of the retransmission IP packet by the transmitting unit is switched.

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