Media transmission system, sending proxy device, receiving proxy device, media transmission method, and program

Abstract

To stabilize and transmit streams, and reduce transmission costs.SOLUTION: A media transmission system includes a sending proxy device 2 and a receiving proxy device 3. The sending proxy device 3 includes a first conversion unit 21 configured to: convert first streams of two redundant systems transmitted from a media sending device 1 via two different first transmission paths into a second stream of one system; and transmit the second stream to the receiving proxy device 3 via one second transmission path. The receiving proxy device 3 includes a second conversion unit 31 configured to transmit third streams of two redundant systems obtained by copying the second stream received via the second transmission path, to a media receiving device 4 via two different third transmission paths.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a media transmission system, a sending proxy device, a receiving proxy device, a media transmission method, and a program. [Background technology]

[0002] The SMPTE Media over IP system is a video transmission standard for transmitting broadcast program material defined by the Society of Motion Picture and Television Engineers (SMPTE). In this system, the SMPTE ST 2022-7 standard for stable video transmission is used. The transmitting side simultaneously transmits two redundant streams, a primary and a secondary stream, and the receiving side receives the two streams. If an abnormality occurs in one of the streams, the receiving side immediately switches to the other normal stream without interruption (Non-Patent Document 1). In addition to SMPTE ST 2022-7, various other standards exist for SMPTE ST 2022 (Non-Patent Documents 2-8). [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] SMPTE ST 2022-7 Seamless Protection Switching of RTP Datagrams [Non-patent document 2] SMPTE ST 2110-10 System Timing and Definitions [Non-patent document 3] SMPTE ST 2110-20 Uncompressed Active Video [Non-patent document 4] SMPTE ST 2110-22 Constant Bit-Rate Compressed Video [Non-patent document 5] SMPTE ST 2110-30 PCM Digital Audio [Non-patent document 6] SMPTE ST 2110-40 SMPTE ST 291-1 Ancillary Data [Non-Patent Document 7] AMWA IS-04 NMOS Discovery and Registration Specification, Internet<https: / / specs.amwa.tv / is-04 / releases / v1.3.2 / docs / Overview.html#introduction> [Non-patent document 8] Junichiro Kawamoto. SMPTE ST 2022. Journal of the Institute of Image Television Engineers. Vol.72, No. 2, pp. 247-250, Summary of the Invention [Problem to be solved by the invention]

[0004] To transmit two redundant streams (primary and secondary) as specified in the SMPTE ST 2022-7 standard, two separate transmission paths must be prepared, which increases costs. Two separate transmission paths can be prepared in two ways: by preparing two lines, or by preparing a single line with double the bandwidth and transmitting the data via a trunk within that line.

[0005] To reduce costs, one stream is transmitted over a single transmission path without redundancy. However, this poses the challenge of making the stream more stable than when transmitting two streams as specified in the SMPTE ST 2022-7 standard.

[0006] The present disclosure has been made in consideration of the above-mentioned problems, and aims to stabilize and transmit streams while reducing transmission costs. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, one aspect of the present disclosure is a media transmission system comprising a transmitting proxy device and a receiving proxy device, wherein the transmitting proxy device comprises a first conversion unit that converts two redundant first streams transmitted from a media transmitting device via two different first transmission paths into one second stream and transmits the second streams to the receiving proxy device via one second transmission path, and the receiving proxy device comprises a second conversion unit that copies the second streams received via the second transmission path to form two redundant third streams and transmits them to a media receiving device via two different third transmission paths.

[0008] One aspect of the present disclosure is a transmitting proxy device in a media transmission system comprising a transmitting proxy device and a receiving proxy device, the transmitting proxy device comprising a conversion unit that converts two redundant streams transmitted from a media transmitting device via two different first transmission paths into one stream and transmits the stream to the receiving proxy device via one second transmission path.

[0009] One aspect of the present disclosure is a receiving proxy device in a media transmission system comprising a transmitting proxy device and a receiving proxy device, the receiving proxy device comprising a conversion unit that receives one stream transmitted from the transmitting proxy device via one transmission path, and transmits two streams obtained by duplicating the stream to a media receiving device via two different transmission paths.

[0010] One aspect of the present disclosure is a transmission method performed by a media transmission system including a transmitting proxy device and a receiving proxy device, in which the transmitting proxy device converts two redundant first streams transmitted from a media transmitting device via two different first transmission paths into one second stream and transmits the second streams to the receiving proxy device via one second transmission path, and the receiving proxy device receives the second streams via the second transmission path and transmits two redundant third streams, which are obtained by duplicating the second streams, to a media receiving device via two different third transmission paths.

[0011] One aspect of the present disclosure is a program that causes a computer to function as the transmission proxy device.

[0012] One aspect of the present disclosure is a program that causes a computer to function as the receiving proxy device. [Effects of the Invention]

[0013] According to the present disclosure, it is possible to stabilize and transmit a stream and reduce transmission costs. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a transmission system according to the first embodiment. [Figure 2] FIG. 2 is a diagram showing a schematic diagram of stream redundancy. [Figure 3] FIG. 3 is a diagram for explaining a transmission setting method for a sending proxy and a receiving proxy. [Figure 4] FIG. 4 illustrates an example of the configuration of a transmission proxy. [Figure 5] FIG. 5 illustrates an example of the configuration of a receiving proxy. [Figure 6] FIG. 6 is a flowchart showing an example of the operation of the transmission proxy. [Figure 7] FIG. 7 is a flowchart showing an example of the operation of the receiving proxy. [Figure 8] FIG. 8 is a diagram illustrating an example of the configuration of a transmission system according to the second embodiment. [Figure 9] FIG. 9 illustrates an example of the configuration of a transmission proxy according to the second embodiment. [Figure 10] FIG. 10 illustrates an example of the configuration of a receiving proxy according to the second embodiment. [Figure 11] FIG. 11 is a diagram illustrating an example of the configuration of a receiving proxy according to the third embodiment. [Figure 12] FIG. 12 is a diagram illustrating an example of the configuration of a transmission proxy according to the fourth embodiment. [Figure 13] FIG. 13 illustrates an example of the configuration of a transmission proxy according to the fifth embodiment. [Figure 14] FIG. 14 shows an example of a hardware configuration. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings, the same reference numerals are used to denote the same parts, and descriptions thereof will not be repeated.

[0016] First Embodiment 1 is a diagram showing an example of the configuration of a transmission system according to this embodiment. The transmission system (media transmission system) according to this embodiment comprises a transmitting proxy 2 (transmitting proxy device) located at a sending location (hereinafter referred to as a "venue"), and a receiving proxy 3 (receiving proxy device) located at a receiving location (hereinafter referred to as a "studio").

[0017] A transmission proxy 2 and a media transmission device 1 are located in the venue. A network (private network) such as a LAN is constructed within the venue. The media transmission device 1 is connected to the transmission proxy 2 via two different transmission paths within the venue's network. The network within the venue allows for redundant transmission paths to be made relatively inexpensive and easy. As defined by the SMPTE ST 2022-7 standard, the media transmission device 1 simultaneously transmits two redundant streams (primary and secondary) to the transmission proxy 2 via different transmission paths within the venue. The media transmission device 1 has dual ports (two transmission units) and outputs streams to the two transmission paths using the dual ports.

[0018] The transmission proxy 2 receives the two streams output from the media transmitter 1 via different transmission paths, and, similar to the media receiver 4, converts the two received streams into a single stream in a complete state as long as the stream is received in a normal state on one of the transmission paths, and inputs the single stream into a single transmission path (carrier line). In other words, the transmission proxy 2 behaves as the media receiver 4 with respect to the media transmitter 1, and converts the redundant streams into a single stream.

[0019] The sending proxy 2 has a dual port (two receiving units) on the media sending device 1 side, and uses the dual ports to input redundant streams and convert them into a single stream. The sending proxy 2 also has a single port (sending unit) on the receiving proxy 3 side, and uses the single port to send the single stream to the receiving proxy 3.

[0020] The transmission path between the studio and venue uses a high-quality transmission path such as a carrier line operated by a telecommunications carrier. Carrier lines have guaranteed line quality and almost no packet loss occurs. In this embodiment, a carrier line is used, but the present invention is not limited to this.

[0021] The receiving proxy 3 receives one stream transmitted from the transmitting proxy 2 via a carrier line and converts the received stream into two redundant streams in accordance with SMPTE ST 2022-7. The receiving proxy 3 then transmits the redundant streams to the media receiving device 4 via different transmission paths within the studio. In other words, the receiving proxy 3 behaves as the media transmitting device 1 with respect to the media receiving device 4 and processes the stream in accordance with SMPTE ST 2022-7.

[0022] The receiving proxy 3 has a single port (receiving unit) on the transmitting proxy 2 side, and inputs one stream using this single port. The receiving proxy 3 also has dual ports (two transmitting units) on the media receiving device 4 side, and outputs redundant streams using these dual ports.

[0023] A receiving proxy 3 and a media receiving device 4 are placed in the studio. A network (private network) such as a LAN is constructed within the studio. The media receiving device 4 is connected to the receiving proxy 3 via two different transmission paths of the network within the studio. The network within the studio can easily make the transmission paths redundant at a relatively low cost.

[0024] As defined in the SMPTE ST 2022-7 standard, the media receiving device 4 receives two redundant streams (primary and secondary) from the receiving proxy 3 via different transmission paths within the studio, and if a failure occurs in the active transmission path, it switches to the stream on the redundant (standby) transmission path and outputs the playback stream in as perfect a state as possible to a playback device (not shown) such as a monitor. The media receiving device 4 has dual ports (two receiving units) on the receiving proxy 3 side and receives the redundant streams using the dual ports.

[0025] In this embodiment, two streams (primary and secondary) are transmitted within the venue and studio using redundant transmission paths defined by the SMPTE ST 2022-7 standard. Meanwhile, a single transmission path (single line) is used to transmit a single stream between the venue and studio. Because the transmission paths within the venue and studio are private networks with inferior communication quality compared to carrier lines, redundant stream transmission via separate transmission paths is maintained. Meanwhile, the transmission path between the venue and studio is a high-quality transmission path, such as a carrier line, which guarantees line quality and almost eliminates packet loss, ensuring high stream stability even with a single transmission path. As a result, in this embodiment, using a single high-quality transmission path between the sending proxy 2 and the receiving proxy 3 reduces transmission costs and achieves stream stability.

[0026] 2 is a diagram showing a schematic diagram of stream redundancy in the transmission system of this embodiment. A stream is made up of media packets. In FIG. 2, the stream is depicted as a media packet.

[0027] A media transmitter 1 outputs two lines of redundant media packets 1 and 2, which are made redundant in accordance with the SMPTE ST 2022-7 standard, to two redundant transmission paths 1A and 1B. The payloads of the media packets 1 and 2 are the same. As long as the two lines of redundant media packets 1 and 2 are received normally on either one of the transmission paths 1A and 1B, a transmission proxy 2 uses the media packets 1 and 2 to generate one line of media packets 3 that is as complete as possible, and outputs this to the carrier line of the transmission path 2.

[0028] For example, when transmission path 1A is normal and media packet 1 is received correctly, the transmission proxy 2 inputs media packet 1 to the carrier line as media packet 3. Furthermore, when a failure occurs on transmission path 1A and media packet 1 cannot be received correctly, but media packet 2 on transmission path 1B is received correctly, the transmission proxy 2 switches the media packet to be output to the carrier line from media packet 1 to media packet 2. In other words, the transmission proxy 2 receives media packets 1 and 2 transmitted via transmission paths 1A and 1B, selects the normal media packet, and outputs it to the carrier line as media packet 3 of a single stream.

[0029] The receiving proxy 3 receives one system of media packets 3 via the carrier line, and redundancies the media packets 3 in the same way as the media transmitter 1, reconstructing them into two systems of media packets 3 and 4, which are output to different transmission paths 3A and 3B within the studio. Specifically, the receiving proxy 3 copies the payload of the media packets 3 to generate media packets 4, and redundancies the media packets 3 and 4 into two systems. The payloads of the media packets 3 and 4 are the same.

[0030] The media receiving device 4 receives media packets 3 and 4 via transmission paths 3A and 3B, selects normal media packets, and outputs them as a single playback stream. For example, if a failure occurs on transmission path 3A and media packet 3 cannot be received correctly, but media packet 4 on transmission path 3B is received correctly, the media receiving device 4 switches the media packets to be output as the playback stream from media packet 3 to media packet 4. The playback stream is output to a monitor or the like and played back.

[0031] It should be noted that the media packets of this embodiment do not need to be provided with a special header field, and the default headers determined in ST2110-20, 30, and 40 can be used as the headers.

[0032] 3 is a diagram for explaining the transmission setting method for the transmitting proxy 2 and receiving proxy 3. When performing Media over IP transmission using ST2022 or ST2110, transmission settings such as IP addresses are required for the transmitting proxy 2 and receiving proxy 3. The transmitting proxy 2 must follow (reproduce) the settings of the media receiver 4, and the receiving proxy 3 must follow the settings of the media transmitter 1.

[0033] In this embodiment, the sending proxy 2 and receiving proxy 3 are configured using NMOS (IS-04: Query and Register) and RDS5 (Registration and Discovery Server), but this is not limiting. NMOS (IS-04) is one of the specifications provided by AMWA (Advanced Media Workflow Association), and enables the discovery and registration of devices on a network and the disclosure of the functions of each device.

[0034] The illustrated RDS 5 comprises a sending side instance 6 that acquires and transmits transmission setting information (hereinafter referred to as "setting information") of the media transmitting device 1, and a receiving side instance 7 that acquires and transmits setting information of the media receiving device 4, and each instance comprises a Registry 61, 71, a Registration Service 62, 72, and a Query Service 63, 73. The setting information includes transmission-related information such as a src IP address, a dest IP address, a subnet mask, a gateway, a ttl, a src UDP port, and a dest UDP port.

[0035] The procedure for transmission settings for receiving proxy 3 is as follows:

[0036] First, by IS-04 detection (Query) and registration (Register), the media transmitter 1 and the media receiver 4 are detected and registered in the Registration Services 62 and 72 of the RDS 5. It is assumed that the media transmitter 1 is registered in the Registration Service 62, and the media receiver 4 is registered in the Registration Service 72.

[0037] Then, the setting information of the media transmitting device 1 is transmitted to the Registration Service 62 (S11). The Registration Service 62 transmits the received setting information to the receiving side instance 7 via the Registry 61 (S12, S13).

[0038] The Registry 71 of the receiving-side instance 7 receives the setting information of the media transmitter 1 and sends it to the receiving proxy 3 via the Query Service 73 (S14, S15). The receiving proxy 3 receives the setting information of the media transmitter 1 and uses that setting information to set its own transmission settings, such as its IP address, to the same as those of the media transmitter 1. In other words, the receiving proxy 3 reflects the setting information of the media transmitter 1 in its own transmission settings. Finally, NMOS (IS-05: Connection Control (Device Connection Management)) is used to set up a connection for a redundant path between the media transmitter 1 and the media receiver. This allows the receiving proxy 3 to be set up so that it can transmit a redundant stream to the media receiver 4, just like the media transmitter 1.

[0039] The procedure for setting up transmission for sending proxy 2 is as follows:

[0040] First, the media transmitter 1 and media receiver 4 are detected by IS-04 detection (Query) and registration (Register) and are registered in the Registration Services 62 and 72 of the RDS 5. Then, the setting information of the media receiver 4 is sent to the Registration Service 72 (S21). The Registration Service 72 sends the received setting information to the sending side instance 6 via the Registry 71 (S22, S23).

[0041] The Registry 61 of the sending side instance 6 receives the setting information of the media receiver 4 and sends it to the sending proxy 2 via the Query Service 63 (S24, S25). The sending proxy 2 receives the setting information of the media receiver 4 and uses that setting information to set its own transmission settings, such as its IP address, to the same as those of the media receiver 4. In other words, the sending proxy 2 reflects the setting information of the media receiver 4 in its own transmission settings. Finally, NMOS (IS-05: Connection Control (Device Connection Management)) is used to set up a connection for a redundant path between the media transmitter 1 and the media receiver. This allows the sending proxy 2 to be set up so that it can receive a redundant stream from the media transmitter 1, just like the media receiver 4.

[0042] In the illustrated example, the setting information 300 on the media receiver 4 side of the receiving proxy 3 reflects the setting information 100 on the media transmitter 1, and the setting information 200 on the media transmitter 1 side of the transmitting proxy 2 reflects the setting information 400 on the media receiver 4. Note that an HTTP transaction is used for transmission and reception between the RDS 5 and external devices, and a general transaction is used within the RDS 5.

[0043] In this embodiment, NMOS is used for the transmission setting of the sending proxy 2 and the receiving proxy 3, but the present invention is not limited to this.

[0044] Fig. 4 is a diagram showing an example of the configuration of the transmitting proxy 2. The transmitting proxy 2 shown in Fig. 4 includes a conversion unit 21. The conversion unit 21 (first conversion unit) converts two redundant streams (first streams) transmitted from the media transmitting device 1 via two different transmission paths (first transmission paths) into one stream (second stream), and transmits the stream to the receiving proxy 3 via one transmission path (second transmission path).

[0045] The conversion unit 21 has two receiving units 211, a stream switching unit 212, and a transmitting unit 213. The two receiving units 211 each receive two streams. Specifically, each receiving unit 211 receives one of the two streams transmitted from the media transmitter 1 and outputs the received stream to the stream switching unit 212. The setting information of the receiving unit 211 is set using setting information for the media receiver 4 to receive two streams. In order to receive the streams transmitted by the media transmitter 1, the setting information of the media receiver 4 described above is set in advance in the receiving unit 211 using an NMOS or the like. The two receiving units 211 are set so that they can always receive two streams. This setting means that the setting of the receiving unit 211 is not changed even if a stream failure occurs on one side.

[0046] In accordance with the ST2022-7 standard, stream switching unit 212 selects one of the two streams transmitted from media transmission device 1 and outputs the selected stream to transmission unit 213. If a failure occurs in one of the selected streams (if a failure is detected), stream switching unit 212 seamlessly switches to the other stream and outputs the other stream to transmission unit 213. For example, if stream 1 is being received normally in the primary, stream switching unit 212 selects primary stream 1 and outputs it to transmission unit 213, but if it detects that a failure has occurred in the primary, stream switching unit 212 switches to secondary stream 2 and outputs it to transmission unit 213.

[0047] The transmitter 213 transmits one stream output from the stream switching unit 212 to the receiving proxy 3 via the carrier line transmission path. Inter-proxy setting information (transmission setting information) for transmitting the stream to the receiving proxy 3 is set in advance in the transmitter 213. The setting information for the transmitter 213 only needs to match the transmission and reception settings between the transmitting proxy 2 and the receiving proxy 3. The user can freely decide whether to set the Primary or Secondary setting of the media transmitter 1 in the transmitter 213. The inter-proxy setting information includes transmission-related information such as, for example, src IP address, dest IP address, subnet mask, gateway, ttl, src udp port, and dest udp port.

[0048] Fig. 5 is a diagram showing an example of the configuration of the receiving proxy 3. The receiving proxy 3 shown in Fig. 5 includes a conversion unit 31 (second conversion unit). The conversion unit 31 copies and makes redundant two streams (third streams) from a stream (second stream) received via a carrier line (second transmission path), and transmits the resulting streams to the media receiving device 4 via two different transmission paths (third transmission paths).

[0049] The illustrated conversion unit 31 has a receiving unit 311, a stream redundancy unit 312, and two transmitting units 213. The receiving unit 311 receives the stream transmitted from the transmitting proxy 2 and outputs it to the stream redundancy unit 312. The receiving unit 311 is preset with setting information between the proxies for receiving the stream. The setting information for the receiving unit 311 only needs to match the sending and receiving settings between the transmitting proxy 2 and the receiving proxy 3. The user can freely decide whether to set the receiving unit 311 to the Primary or Secondary setting of the media receiving device 4.

[0050] The stream redundancy unit 312 duplicates one stream transmitted from the transmission proxy 2 into two streams for redundancy in accordance with the ST2022-7 standard, and outputs the duplicated streams to the transmission unit 313 .

[0051] The two transmitters 313 transmit two streams, respectively. Specifically, the transmitters 313 transmit the two streams copied by the stream redundancy unit 312 to the media receiver 4. The setting information of the transmitters 313 is set using setting information for the media transmitter 1 to transmit two streams. In order to transmit the streams, the setting information of the media transmitter 1 described above is set in advance in the transmitters 313 using NMOS or the like.

[0052] FIG. 6 is a flowchart showing an example of the operation of the transmission proxy 2.

[0053] The transmitting proxy 2 receives two streams (primary and secondary) transmitted from the media transmitter 1 via different transmission paths (S31). The transmission settings for the transmitting proxy 2 to receive the two streams use the setting information of the media receiver 4. The transmitting proxy 2 checks whether there is a failure in each of the received streams in accordance with the ST2022-7 standard (S32). If there is no failure in the primary stream, the transmitting proxy 2 selects the primary stream as the stream to be transmitted (S33). The transmitting proxy 2 then transmits the selected stream to the receiving proxy 3 via the carrier line (S35). The transmission settings for the transmitting proxy 2 to transmit the streams use the setting information between the proxies described above.

[0054] On the other hand, if the transmitting proxy 2 detects a failure in the primary stream in S32, it selects the secondary stream as the stream to be transmitted in accordance with the ST2022-7 standard (S34). That is, the transmitting proxy 2 switches the stream to be transmitted from primary to secondary. Then, the transmitting proxy 2 transmits the selected stream to the receiving proxy 3 via the carrier line (S35).

[0055] FIG. 7 is a flowchart showing an example of the operation of the receiving proxy 3.

[0056] The receiving proxy 3 receives one stream transmitted from the transmitting proxy 2 via the carrier line (S41). The transmission settings for the receiving proxy 3 to receive the stream use the setting information between the proxies described above.

[0057] The receiving proxy 3 duplicates the received stream in accordance with the ST2022-7 standard to create two redundant streams (S42). The receiving proxy 3 transmits the two streams to the media receiving device 4 via different transmission paths within the studio (S43). The setting information of the media transmitting device 1 is used for the transmission settings required for the receiving proxy 3 to transmit the two streams.

[0058] <Second embodiment> 8 is a diagram showing an example of the configuration of a transmission system according to the second embodiment. The illustrated example differs from the first embodiment in that a PTP-GM6 is arranged on the transmitting side and the two streams transmitted by the media transmitter 1 include a PTP synchronization signal.

[0059] The PTP GM (Grand Master) 6 is a device that distributes highly accurate time in accordance with the PTP (Precision Time Protocol). PTP is defined in IEEE1588 and is a protocol for synchronizing clocks and time with high precision. Highly accurate time synchronization can be achieved by synchronizing the PTP GM6 clock with a GPS (GNSS) signal.

[0060] The PTP GM 6 periodically transmits a PTP synchronization signal (PTP packet) to the media transmitter 1. As a result, the media transmitter 1 transmits two streams including the PTP synchronization signal to the transmission proxy 2 in accordance with SMPTE ST 2059-1 / 2.

[0061] 9 is a diagram showing an example of the configuration of a transmission proxy 2 of this embodiment. The illustrated transmission proxy 2 differs from the transmission proxy 2 of the first embodiment in that it includes a PTP control unit 22 (first synchronization control unit) that performs PTP synchronization. In the illustrated conversion unit 21, the receiving unit 211 receives a stream including a PTP synchronization signal, the stream switching unit 212 outputs the PTP synchronization signal to the PTP control unit 22, and the transmitting unit 213 inserts the PTP synchronization signal output from the PTP control unit 22 into the stream to be transmitted. In other respects, the conversion unit 21 of this embodiment is similar to the conversion unit 21 of the first embodiment.

[0062] The PTP control unit 22 adjusts the phase synchronization of the PTP synchronization signal included in the stream and outputs the adjusted PTP synchronization signal to the conversion unit 21. The conversion unit 21 transmits a stream including the adjusted PTP synchronization signal. Specifically, the PTP control unit 22 has a function as a BC (Boundary Clock), adjusts the phase synchronization of the PTP synchronization signal, and redistributes the PTP synchronization signal. That is, when a PTP synchronization signal defined in SMPTE ST 2059 is input from the stream switching unit 212, the PTP control unit 22 operates as a slave with respect to the upper master (media transmission device 1) to correct its own clock, and operates as a master with respect to the lower slave (reception proxy 3) to output the adjusted PTP synchronization signal to the transmission unit 213. As a result, the PTP synchronization signal is included in the stream transmitted by the transmission unit 213. The stream switching unit 212 outputs the PTP synchronization signal included in the stream selected as the stream to be transmitted to the PTP control unit 22.

[0063] 10 is a diagram showing an example of the configuration of a receiving proxy 3 of this embodiment. The receiving proxy 3 shown in the figure differs from the receiving proxy 3 of the first embodiment in that it includes a PTP control unit 32 (second synchronization control unit) that performs PTP synchronization. In the illustrated conversion unit 31, the receiving unit 311 receives a stream including a PTP synchronization signal, the stream redundancy unit 312 outputs the PTP synchronization signal to the PTP control unit 32, and each transmission unit 313 inserts the PTP synchronization signal output from the PTP control unit 32 into the stream. In other respects, the conversion unit 31 of this embodiment is similar to the conversion unit 31 of the first embodiment.

[0064] The PTP control unit 32 adjusts the phase synchronization of the PTP synchronization signal included in the stream and outputs the adjusted PTP synchronization signal to the conversion unit 31. The conversion unit 31 transmits two streams including the adjusted PTP synchronization signal. Specifically, the PTP control unit 32, like the PTP control unit 22 of the transmission proxy 2, has a function as a BC, adjusts the phase synchronization of the PTP synchronization signal, and redistributes the PTP synchronization signal. That is, when the PTP synchronization signal defined in SMPTE ST 2059 is input from the stream redundancy unit 312, the PTP control unit 32 operates as a slave with respect to the upper master (transmission proxy 2) and corrects its own clock, and operates as a master with respect to the lower slave (media receiving device 4). The PTP control unit 32 outputs PTP synchronization signals to two transmission units 313, respectively. As a result, the streams transmitted by each transmission unit 313 include a PTP synchronization signal.

[0065] <Third embodiment> 11 is a diagram showing an example of the configuration of a transmission system according to the third embodiment. The transmitting proxy 2 and receiving proxy 3 according to this embodiment differ from the transmitting proxy 2 and receiving proxy 3 according to the first embodiment in that they include error correction units (FEC) 23 and 33 in addition to conversion units 21 and 31, respectively. The conversion units 21 and 31 of the transmitting proxy 2 and receiving proxy 3 are the same as those in the first embodiment.

[0066] The error correction units 23 and 33 perform forward error correction (FEC) as specified in ST2022-1 and ST2022-5. The error correction unit 23 (first error correction unit) of the transmission proxy 2 adds error correction packets to the stream to be transmitted. Specifically, the error correction unit 23 arranges media packets included in the stream in a predetermined manner to generate error correction packets. The conversion unit 21 transmits the stream including the error correction packets.

[0067] The error correction unit 33 (second error correction unit) of the reception proxy 3 corrects errors in the stream using error correction packets. Specifically, when the error correction unit 33 detects an error such as discontinuity in the sequence of media packets or a media packet not being received for a certain period of time, it uses the error correction packets to restore the lost media packet. As a result, in this embodiment, the stream transmitted over a single system can be transmitted and received with higher reliability.

[0068] <Fourth embodiment> 12 is a diagram showing an example of the configuration of a transmission system according to the fourth embodiment. The transmitting proxy 2 and receiving proxy 3 according to this embodiment differ from the transmitting proxy 2 and receiving proxy 3 according to the first embodiment in that they include retransmission control units (ARQ) 24 and 34 in addition to conversion units 21 and 31, respectively. The conversion units 21 and 31 of the transmitting proxy 2 and receiving proxy 3 are the same as those in the first embodiment.

[0069] The retransmission control units 24, 34 perform ARQ (Automatic Repeat Request) of the STR standard. When the retransmission control unit 34 (second retransmission control unit) of the receiving proxy 3 detects an error in the stream (when an error is detected in a media packet), it requests the transmitting proxy 2 to retransmit the erroneous media packet. In response to a request from the receiving proxy device, the retransmission control unit 24 (first retransmission control unit) of the transmitting proxy 2 retransmits the requested media packet of the stream. As a result, in this embodiment, streams transmitted over a single system can be transmitted and received with higher reliability.

[0070] <Fifth embodiment> 13 is a diagram showing an example of the configuration of a transmission system according to the fifth embodiment. The transmitting proxy 2 according to this embodiment differs from the transmitting proxy 2 according to the first embodiment in that it includes an encoding unit (ENC: Encoder) 25 in addition to a conversion unit 21. The receiving proxy 3 according to the first embodiment differs from the receiving proxy 3 according to the first embodiment in that it includes a decoding unit (DEC: Decode) 35 in addition to a conversion unit 31. The conversion units 21 and 31 of the transmitting proxy 2 and receiving proxy 3 are the same as those of the first embodiment.

[0071] The encoding unit 25 encodes and compresses the stream. Specifically, the encoding unit 25 encodes the media packets of the stream to be transmitted based on certain rules, and compresses the amount of data. The transmitting proxy 2 transmits the encoded (compressed) stream to the receiving proxy 3. The converting unit 31 of the receiving proxy 3 receives the compressed stream, and the decoding unit 35 decodes the decoded stream. The converting unit 31 makes the decoded stream redundant and transmits it to the media receiving device 4. As a result, in this embodiment, it is possible to reduce the amount of data transmitted for a stream transmitted over a single system.

[0072] <Action and effect> The transmission system of this embodiment described above comprises a sending proxy 2 and a receiving proxy 3. The sending proxy 2 comprises a conversion unit 21 that converts two redundant first streams transmitted from the media sending device 1 via two different first transmission paths into one second stream and transmits the second stream to the receiving proxy device via one second transmission path. The receiving proxy 3 comprises a conversion unit 31 that copies the second stream received via the second transmission path to create two redundant third streams and transmits them to the media receiving device 4 via two different third transmission paths.

[0073] This enables the stream to be transmitted in a stabilized manner and transmission costs to be reduced. Specifically, even when transmitting one stream between the transmitting proxy 2 and the receiving proxy 3 via one transmission path, the reliability of the stream can be improved by transmitting two streams between the media transmitting device 1 and the transmitting proxy 2 and between the receiving proxy 3 and the media receiving device 4. Furthermore, compared to using two transmission paths for redundancy according to SMPTE ST 2022-7, the number of transmission paths or the bandwidth used between the transmitting proxy 2 and the receiving proxy 3 can be halved, thereby reducing transmission costs.

[0074] The sending proxy 2 and receiving proxy 3 may also include PTP control units 22 and 32. This makes it possible to achieve highly accurate time synchronization.

[0075] The sending proxy 2 may also include at least one of the error correction unit 23 of the third embodiment and the retransmission control unit 24 of the fourth embodiment, and the receiving proxy 3 may also include at least one of the error correction unit 33 of the third embodiment and the retransmission control unit 34 of the fourth embodiment. This improves the reliability of data transmission between the sending proxy 2 and receiving proxy 3, which transmit one stream.

[0076] Furthermore, the sending proxy 2 may include an encoding unit 25, and the receiving proxy 3 may include a decoding unit 35. This makes it possible to reduce the amount of data transferred between the sending proxy 2 and the receiving proxy 3.

[0077] <Hardware configuration> The sending proxy 2 and receiving proxy 3 described above can use, for example, a general-purpose computer system as shown in Fig. 14. The computer system shown in the figure includes a CPU (Central Processing Unit, processor) 901, memory 902, storage 903 (HDD: Hard Disk Drive, SSD: Solid State Drive), communication device 904, input device 905, and output device 906. The memory 902 and storage 903 are storage devices. In this computer system, the CPU 901 executes a predetermined program loaded onto the memory 902, thereby realizing the functions of the sending proxy 2 and receiving proxy 3.

[0078] The sending proxy 2 and receiving proxy 3 may be implemented on a single computer or on multiple computers. The sending proxy 2 and receiving proxy 3 may be virtual machines implemented on a computer. The programs for the sending proxy 2 and receiving proxy 3 may be stored on a computer-readable recording medium such as a HDD, SSD, USB (Universal Serial Bus) memory, CD (Compact Disc), or DVD (Digital Versatile Disc), or may be distributed via a network. The computer-readable recording medium is, for example, a non-transitory recording medium.

[0079] The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the present disclosure. The second to fifth embodiments may be combined in any desired manner. [Explanation of symbols]

[0080] 1: Media transmitter 2: Sending proxy (sending proxy device) 21: Conversion unit (first conversion unit) 211: Receiving unit 212: Stream switching unit 213: Transmission unit 22: PTP control unit (first synchronization control unit) 23: Error correction unit (first error correction unit) 24: Retransmission control unit (first retransmission control unit) 25: Encoding section 3: Receiving proxy (receiving proxy device) 31: Conversion unit (second conversion unit) 311: Receiving unit 312: Stream redundancy section 313: Transmission unit 32: PTP control unit (second synchronization control unit) 33: Error correction unit (first error correction unit) 34: Retransmission control unit (second retransmission control unit) 35: Decoding section 4: Media receiving device 5 :RDS(Registration and Discovery Server) 6:PTP-GM

Claims

1. A media transmission system comprising a sending proxy device and a receiving proxy device, The transmission proxy device a first conversion unit that converts two redundant first streams transmitted from a media transmitter via two different first transmission paths into one second stream and transmits the second stream to the receiving proxy device via one second transmission path; The receiving proxy device a second conversion unit that duplicates the second stream received via the second transmission path to make the second stream redundant and transmits the duplicated third streams to a media receiving device via two different third transmission paths; Media transmission system.

2. The transmission proxy device a first synchronization control unit that adjusts phase synchronization of a PTP synchronization signal included in the first stream and outputs the adjusted PTP synchronization signal to the first conversion unit; the first conversion unit transmits the second stream including the adjusted PTP synchronization signal; The receiving proxy device a second synchronization control unit that adjusts phase synchronization of the PTP synchronization signal included in the second stream and outputs the adjusted PTP synchronization signal to the second conversion unit; The second conversion unit transmits the third stream including the adjusted PTP synchronization signal. The media transmission system of claim 1 .

3. The transmission proxy device the second stream includes at least one of a first error correction unit that adds an error correction packet to the second stream, and a first retransmission control unit that retransmits a requested media packet of the second stream in response to a request from a receiving proxy device; The receiving proxy device and a second retransmission control unit that, when an error in the second stream is detected, requests the transmission proxy device to retransmit the erroneous media packet. The media transmission system of claim 1 .

4. The transmission proxy device an encoding unit that encodes and compresses the second stream; The receiving proxy device a decoding unit for decoding the second stream; The media transmission system of claim 1 .

5. the first conversion unit includes two receiving units that respectively receive the two systems of the first streams, and transmission setting information of the receiving units is set using transmission setting information for the media receiving device to receive the third stream; The second conversion unit includes two transmission units for respectively transmitting the two systems of the third streams, and transmission setting information of the transmission units is set using transmission setting information for the media transmitter to transmit the first stream. The media transmission system of claim 1 .

6. A transmitting proxy device in a media transmission system including a transmitting proxy device and a receiving proxy device, a conversion unit that converts two redundant streams transmitted from a media transmitting device via two different first transmission paths into one stream and transmits the stream to the receiving proxy device via one second transmission path; Outgoing proxy device.

7. A receiving proxy device in a media transmission system including a sending proxy device and a receiving proxy device, a conversion unit that receives one stream transmitted from the transmission proxy device via one transmission path, duplicates the stream, and transmits two redundant streams to a media receiving device via two different transmission paths; Incoming proxy device.

8. A transmission method performed by a media transmission system including a sending proxy device and a receiving proxy device, comprising: The transmission proxy device converting two redundant first streams transmitted from a media transmitter via two different first transmission paths into one second stream; transmitting the second stream to the receiving proxy device via a second transmission path; The receiving proxy device receiving the second stream via the second transmission path; Two systems of third streams obtained by duplicating the second stream and making them redundant are transmitted to a media receiving device via two different third transmission paths. Media transmission method.

9. A program that causes a computer to function as the transmission proxy device according to claim 6.

10. A program that causes a computer to function as the receiving proxy device according to claim 7.

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