Video transmission system

Abstract

To correct a reception error generated in a base station when a video signal is wirelessly transmitted using an FPU, thereby improving stability of video transmission.SOLUTION: An FPU 21 of a terminal-side transmitter 2-1 transmits an IP signal including a video via an FPU line 4. A mobile communication terminal 22-1 transmits an IP signal including the same video via a mobile communication line 5. A base station-side transmitter 3-1 receives the IP signals, and stores them in an FPU-side buffer 32 and a mobile-side buffer 34, respectively. A receiver 35 on the base station-side transmitter 3-1 receives the IP signals from the FPU-side buffer 32 and the mobile-side buffer 34, and outputs, unless the IP signal from the FPU-side buffer 32 is lacking, the IP signal to a video compression / decompression unit 36 to compress / decompress the signal. When the IP signal is lacking, the receiver 35 outputs the IP signal from the mobile-side buffer 34 to the video compression / decompression unit 36 to compress / decompress the signal.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a video transmission system that wirelessly transmits a video signal from an FPU (Field Pickup Unit: portable wireless transmission device) on a terminal side to a base station side. [Background technology]

[0002] Traditionally, SDI (Serial Digital Interface) signals have been widely used in program production. SDI is a video signal transmission standard that realizes one-way transmission, constant bit rate, and slave synchronization, and is standardized from SD signals to 8K signals.

[0003] While SDI has the advantage of being able to stably transmit high-definition video signals, it requires the laying of cables, which takes up a lot of time, especially in sports broadcasts.

[0004] Furthermore, FPUs (Field Pickup Units: portable wireless transmission devices) are widely used as devices for wirelessly transmitting video signals (see, for example, Non-Patent Document 1). These FPUs are often used at program production sites as wireless cameras integrated with cameras. In particular, the use of millimeter waves as the transmission frequency of FPUs enables large-capacity transmission, making it possible to wirelessly transmit 4K or 8K video signals, which was previously difficult.

[0005] Since there are limitations to the transmission frequency of FPUs and the equipment for professional use is also limited, it is common to use FPUs to make only some video transmission systems wireless, rather than making all video transmission systems wireless. For this reason, it does not completely eliminate the need for cable laying work.

[0006] Meanwhile, a method that uses a wireless public network is known as a method for wirelessly transmitting a camera's video signal without being restricted by the laying of cables and the frequency and number of pieces of equipment of the wireless camera.

[0007] Devices that wirelessly transmit camera video signals are already commercially available and are used for transmitting video signals from the live broadcasting site of news programs to broadcast stations, etc. By using such devices for live broadcasting programs other than news programs, such as sports, wireless communication can be realized.

[0008] The fifth generation mobile communication system is known as one of the wireless public network lines. This fifth generation mobile communication system includes a system called local 5G that can be used by various entities according to regional and individual needs.

[0009] Local 5G uses TDD (Time Division Duplex) as its duplexing method, and there is a trade-off between the transmission rates for upstream transmission (here, transmission from the camera (terminal) to the base station: uplink) and downstream transmission (here, transmission from the base station to the camera: downlink). [Prior art documents] [Non-patent literature]

[0010] [Non-Patent Document 1] Yamagishi, M. Matsuzaki, M. Shimazaki, Y. Yamazato, N. Nakagawa, Okube, and Iai, “Research and Development of Millimeter Wave 8K Wireless Cameras,” Institute of Image Information and Television Engineers Technical Report, BCT2022-55, Vol. 46, No. 30 Summary of the Invention [Problem to be solved by the invention]

[0011] There are various problems when using a video transmission system using the aforementioned FPU, that is, a video transmission system that wirelessly transmits video signals from the FPU on the terminal side to the base station side for relay programs. For example, because the FPU is a one-way transmission device, if a reception error occurs in the video signal at the base station side, the reception error cannot be corrected.

[0012] On the other hand, there are various problems when using a mobile communication system based on a wireless public network such as the aforementioned local 5G for broadcasting programs. For example, the guaranteed transmission rate in a mobile communication system is lower than that of a video transmission system using an FPU, so the video quality is lower than that of a video transmission system using an FPU.

[0013] Incidentally, in the field of Ethernet (registered trademark) transmission in communication, the SMPTE2022-7 standard is known, which specifies a mechanism for uninterrupted switching when a reception error occurs. This standard specifies a mechanism in which a transmitting side transmits the same packet via multiple lines, and when a receiving side determines that a packet is missing on one of the lines, the missing packet is compensated for uninterruptedly using a packet transmitted on the other line.

[0014] However, this SMPTE2022-7 standard is applicable to Ethernet (registered trademark) transmission, and does not specify a specific application method for wireless transmission. For this reason, the SMPTE2022-7 standard cannot be applied as is to video transmission systems using FPUs and mobile communication systems using wireless public network lines.

[0015] Therefore, the present invention has been made to solve the above-mentioned problems, and its object is to provide a video transmission system that improves the stability of video transmission by correcting reception errors that occur at the base station when wirelessly transmitting a video signal using an FPU. [Means for solving the problem]

[0016] In order to solve the above-mentioned problem, the video transmission system of claim 1 is a video transmission system for wirelessly transmitting video from an FPU (Field Pickup Unit: portable wireless transmission device) provided in a terminal-side transmission device to a base station-side transmission device, the terminal-side transmission device inputting a camera video and a control signal included in a downlink signal transmitted from the base station-side transmission device, compressing and encoding the camera video based on the control signal to generate a TS signal, converting the TS signal into an IP signal, and outputting the IP signal consisting of two systems of identical packets as a first IP signal and a second IP signal, the FPU inputting the first IP signal output by the terminal-side transmission / reception unit, generating a first uplink signal including the first IP signal, and transmitting the first uplink signal to the base station-side transmission device via a wireless line, the FPU inputting the second IP signal output by the terminal-side transmission / reception unit, generating a second uplink signal including the second IP signal, transmitting the second uplink signal to the base station-side transmission device via a wireless line for mobile communication, and transmitting the mobile communication signal from the base station-side transmission device to the wireless line for mobile communication. and a mobile communications terminal that receives the downlink signal including the control signal via a line, wherein the base station side transmission device comprises an FPU receiving unit that receives the first uplink signal from the FPU via the wireless line and stores the first IP signal included in the first uplink signal in an FPU side buffer, a mobile transceiver unit that receives the second uplink signal from the mobile communications terminal via the mobile communications wireless line and stores the second IP signal included in the second uplink signal in a mobile side buffer, generates the downlink signal including the control signal, and transmits the downlink signal to the mobile communications terminal via the mobile communications wireless line, and a mobile transceiver unit that inputs the first IP signal from the FPU side buffer and inputs the second IP signal from the mobile side buffer, determines whether or not there is a loss in the first IP signal, and when it is determined that there is no loss, outputs the first IP signal input from the FPU side buffer, and when it is determined that there is a loss,The present invention is characterized in that it comprises a receiver that outputs the second IP signal input from the mobile side buffer to complement the loss, and a video compression and decoding unit that performs compression and decoding corresponding to the compression and encoding by the terminal side transmitting and receiving unit on the video included in the first IP signal or the second IP signal output by the receiver, thereby generating and outputting a main line broadcast video.

[0017] The video transmission system of claim 2 is the video transmission system of claim 1, wherein the FPU side buffer provided in the base station side transmission device stores the first IP signal in packet units and stores a buffer time t b When the buffer time t has elapsed, the first IP signal is output in packet units, and the second IP signal is stored in the mobile side buffer provided in the base station side transmission device, and the buffer time t mb When time has elapsed, the second IP signal is output in units of packets, and the receiver provided in the base station side transmission device measures an arrival delay time PD indicating a difference in time when the same packet is input for the first IP signal input from the FPU side buffer and the second IP signal input from the mobile side buffer, and if the arrival delay time PD is not 0, identifies the IP signal that was input earlier in the same packet based on the arrival delay time PD, and determines the buffer time t of the FPU side buffer in which the earlier IP signal is stored. b or the buffer time t mb The buffer time t b or the buffer time t mb and if the arrival delay time PD is 0, outputting the first IP signal or outputting the second IP signal.

[0018] The video transmission system of claim 3 is the video transmission system of claim 1 or 2, wherein the terminal-side transmission device further comprises a mobile processing unit, and the mobile transceiver unit of the base station-side transmission device determines whether or not there is a loss in the second IP signal included in the second uplink signal, and if it is determined that there is no loss, stores the second IP signal in the mobile-side buffer, and if it is determined that there is a loss, generates the downlink signal including a retransmission request and transmits the downlink signal to the mobile communication terminal, and the mobile communication terminal of the terminal-side transmission device receives the downlink signal from the mobile transceiver unit and transmits the retransmission request included in the downlink signal to the mobile communication terminal. the mobile processing unit provided in the terminal side transmission device inputs the second IP signal output by the terminal side transceiver unit, stores the second IP signal in a retransmission buffer, and if the retransmission request is not input from the mobile communication terminal, outputs the inputted second IP signal to the mobile communication terminal, and if the retransmission request is input from the mobile communication terminal, inputs the second IP signal from the retransmission buffer and outputs the second IP signal to the mobile communication terminal, and the mobile communication terminal provided in the terminal side transmission device inputs the second IP signal from the mobile processing unit, generates the second uplink signal, and transmits it to the base station side transmission device. Effect of the Invention

[0019] As described above, according to the present invention, when a video signal is wirelessly transmitted using an FPU, reception errors that occur at the base station can be corrected, thereby improving the stability of video transmission. [Brief description of the drawings]

[0020] [Figure 1] 1 is a diagram showing an example of the overall configuration of a video transmission system according to an embodiment of the present invention. [Diagram 2] 2 is a block diagram showing an example of the configuration of a terminal-side transmission device in the video transmission system of the first embodiment. FIG. [Diagram 3]4 is a block diagram showing a configuration example of a terminal-side transmitting / receiving unit. FIG. [Figure 4] 1 is a block diagram showing an example of the configuration of a base station side transmission device in a video transmission system according to a first embodiment. [Diagram 5] 13 is a flowchart illustrating an example of a switching process performed by the receiver. [Figure 6] 11 is a flowchart illustrating an example of input / output processing and an example of synchronization processing by a receiver. [Figure 7] FIG. 11 is a block diagram showing an example of the configuration of a terminal-side transmission device in a video transmission system according to a second embodiment. [Figure 8] 4 is a block diagram showing a configuration example of a mobile processing unit. FIG. [Figure 9] 13 is a flowchart illustrating an example of processing by a mobile processing unit. [Figure 10] FIG. 11 is a block diagram showing a configuration example of a base station side transmission device in a video transmission system according to a second embodiment. [Figure 11] 13 is a flowchart illustrating an example of a retransmission request process performed by a mobile transceiver; [Figure 12] FIG. 1 is a diagram illustrating an example of slot allocation in a TDD system. [Figure 13] FIG. 11 is a diagram illustrating the timing of retransmission of video. [Figure 14] 13 is a flowchart showing an example of setting a buffer time tmb2 of a retransmission buffer. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] The following describes in detail the embodiments of the present invention with reference to the drawings. The present invention is characterized in that in a video transmission system that wirelessly transmits video from an FPU on a terminal side to a base station side, a mobile communication wireless line is added to the FPU wireless line, and when an error occurs in the transmission through the FPU wireless line, the transmission is switched to the mobile communication wireless line without momentary interruption.

[0022] This allows the video from the mobile communication wireless line to be used as a complement when the video from the FPU wireless line is disrupted. In other words, by combining the FPU's video transmission technology with mobile communication technology and the hitless switching technology of SMPTE2022-7, the stability of video transmission can be improved.

[0023] [Video Transmission System] First, a video transmission system according to an embodiment of the present invention will be described. Fig. 1 is a diagram showing an example of the overall configuration of a video transmission system according to an embodiment of the present invention. This video transmission system 1 includes a terminal side transmission device 2 and a base station side transmission device 3.

[0024] The terminal-side transmission device 2 includes an FPU 21 and a mobile communication terminal 22, which will be described later, and inputs camera images, compresses and encodes the camera images, and generates two systems of uplink signals including the compressed and encoded images. The camera images are images captured using a camera, but the terminal-side transmission device 2 may also input images other than the camera images.

[0025] The terminal-side transmission device 2 transmits a first uplink signal including compressed and encoded video from an FPU 21 (described later) via an FPU line 4 to the base-station-side transmission device 3. The terminal-side transmission device 2 also transmits a second uplink signal including the same compressed and encoded video from a mobile communication terminal 22 (described later) via a mobile communication line 5 to the base-station-side transmission device 3.

[0026] The terminal-side transmission device 2 receives a downlink signal including a monitor image, a control signal, and a retransmission request from the base station-side transmission device 3 via the mobile communication line 5, compresses and decodes the monitor image, and outputs the compressed and decoded monitor image. The monitor image is a returned image for a cameraman or the like to check.

[0027] Moreover, the terminal-side transmission device 2 controls, for example, compression encoding and the mobile communication terminal 22 based on the control signal included in the downlink signal. Furthermore, the terminal-side transmission device 2 performs a retransmission process of the video via the mobile communication line 5 based on a retransmission request included in the downlink signal.

[0028] The base station side transmission device 3 receives an uplink signal including video from the terminal side transmission device 2 via the FPU line 4 , and also receives an uplink signal including the same video via the mobile communication line 5 .

[0029] The base station side transmission device 3 compresses and decodes the video received via the FPU line 4, and outputs it as the main broadcast line. Furthermore, if a reception error occurs in the video received via the FPU line 4, causing a loss of video, the base station side transmission device 3 switches without interruption from the video received via the FPU line 4 to the video received via the mobile communication line 5. The base station side transmission device 3 then compresses and decodes the video received via the mobile communication line 5, and outputs it as the main broadcast line.

[0030] This makes it possible to correct reception errors by compensating for missing images received via the FPU line 4 using images received via the mobile communication line 5.

[0031] In the base station side transmission device 3, in the receiver 35 described later, prior to the above-mentioned switching process, the video is input from the buffer on the FPU line 4 side and the buffer on the mobile communication line 5 side, and in order to bring the arrival delay time PD, which is the difference in the arrival time of the input timing, closer to 0, the buffer time of the earlier arrival time (buffer time t b or t mb ) plus the arrival delay time PD.

[0032] This makes it possible to bring the delay time difference between the video received via the FPU line 4 and the video received via the mobile communication line 5 close to zero, thereby achieving synchronization.

[0033] The base station side transmission device 3 generates a downlink signal including a monitor image, a control signal, and a retransmission request, and transmits the downlink signal to the terminal side transmission device 2 via the mobile communication line 5 .

[0034] In this case, when a loss occurs in the video received via the mobile communication line 5, the base station side transmission device 3 generates a downlink signal including a retransmission request and transmits it to the terminal side transmission device 2.

[0035] As a result, even if there is a loss in the video received via the mobile communication line 5, the lost video is resent, so the transmission of the video from the mobile communication line 5 will not be disrupted. In other words, the loss of the video received via the FPU line 4 can be reliably compensated for by using the video received via the mobile communication line 5.

[0036] Incidentally, the video transmission system 1 in FIG. 1 shows the case where video is transmitted, but audio transmission will not be mentioned here since the bit rate is sufficiently smaller than that of video and existing technology is used for audio transmission.

[0037] The terminal side transmission device 2 and the base station side transmission device 3 of the video transmission system 1 shown in Fig. 1 will be described below in two parts, Example 1 and Example 2. Example 1 improves the stability of video transmission by combining the video transmission technology of FPU with mobile communication technology and the hitless switching technology of SMPTE2022-7. Example 2 further improves the stability of video transmission by performing retransmission request processing of mobile communication in addition to the processing of Example 1.

[0038] Example 1 A detailed description will be given of Example 1. As described above, Example 1 improves the stability of video transmission by combining the video transmission technology of FPU with mobile communication technology and the hitless switching technology of SMPTE2022-7.

[0039] (Terminal side transmission device 2 / Example 1) First, a description will be given of a terminal-side transmission device 2 provided in the video transmission system 1 of the embodiment 1. Fig. 2 is a block diagram showing an example of the configuration of the terminal-side transmission device 2 in the video transmission system 1 of the embodiment 1. This terminal-side transmission device 2-1 includes a terminal-side transceiver unit 20, an FPU 21, and a mobile communication terminal 22-1.

[0040] The terminal side transmitting / receiving unit 20 inputs the camera image, and also inputs a downlink signal including a monitor image and a control signal from the mobile communication terminal 22-1. The terminal side transmitting / receiving unit 20 then extracts the output bit rate, resolution, TDD allocation information, etc. from the control signal included in the downlink signal, compresses and encodes the camera image based on the output bit rate, resolution, etc., and generates an IP signal including the compressed and encoded image.

[0041] When the terminal side transceiver 20 generates an IP signal including compressed and encoded video, it distributes the generated IP signal into two systems of IP signals consisting of identical packets, outputs one IP signal to the FPU 21, and outputs the other IP signal to the mobile communication terminal 22-1.

[0042] As a result, an IP signal consisting of a group of IP packets storing the same video is input to the FPU 21 and the mobile communication terminal 22-1.

[0043] The terminal side transmitting / receiving unit 20 compresses and decodes the monitor video included in the downlink signal, and outputs the compressed and decoded monitor video. The terminal side transmitting / receiving unit 20 also outputs terminal control information including TDD allocation information extracted from the control signal included in the downlink signal to the mobile communication terminal 22-1. The details of the terminal side transmitting / receiving unit 20 will be described later.

[0044] The FPU 21 receives an IP signal including video from the terminal-side transceiver 20, performs transmission processing on the IP signal based on a predetermined modulation method for FPU video transmission, and generates an uplink signal including the IP signal. The FPU 21 then transmits the uplink signal to the base station-side transmission device 3-1 (described later) via the FPU line 4. This uplink signal includes the video (compressed and encoded video) stored in the IP signal.

[0045] Mobile communication terminal 22-1 receives an IP signal including video (the same signal as the IP signal input by FPU 21) and terminal control information from terminal-side transceiver 20. Mobile communication terminal 22-1 then performs transmission processing on the IP signal based on TDD allocation information and the like included in the terminal control information for transmitting video in mobile communication, and generates an uplink signal including the IP signal. Mobile communication terminal 22-1 transmits the uplink signal to base station-side transmission device 3-1, which will be described later, via mobile communication line 5. This uplink signal includes video stored in the IP signal (compressed and encoded video).

[0046] The mobile communication terminal 22-1 receives a downlink signal including a monitor video and a control signal from a base station side transmission device 3-1 (described later) via a mobile communication line 5. Then, the mobile communication terminal 22-1 performs reception processing on the downlink signal based on TDD allocation information and the like included in the control signal for performing video transmission of mobile communication, and outputs the downlink signal after reception processing to the terminal side transceiver unit 20.

[0047] The RTP / UDP protocol is used in the wireless section of the mobile communication line 5. The control signal included in the downlink signal is transmitted using a general protocol between a base station and a terminal in wireless access communication.

[0048] (Terminal side transceiver unit 20) 3 is a block diagram showing an example of the configuration of the terminal-side transmitting / receiving unit 20. This terminal-side transmitting / receiving unit 20 includes a video compression encoding unit 23, a transmitter 24, a terminal-side receiving unit 25, a terminal control unit 26, a video compression decoding unit 27, and an encoding control unit 28.

[0049] The video compression encoder 23 inputs the camera video and also inputs upstream encoding control information from the encoding control unit 28. Then, the video compression encoder 23 performs compression encoding of the camera video based on the upstream encoding control information, and generates a TS signal including the compressed and encoded video. The video compression encoder 23 outputs the TS signal to the transmitter 24.

[0050] The uplink coding control information includes an output bit rate, a resolution, etc., and the output bit rate, the resolution, etc. are data included in the control signal of the downlink signal received from the base station side transmission device 3 via the mobile communication line 5.

[0051] The transmitter 24 is a device that complies with SMPTE2022, receives the TS signal from the video compression encoding unit 23, converts the TS signal into an IP signal, and outputs the IP signal to the FPU 21 and the mobile communication terminal 22-1.

[0052] The conversion process from TS signals to IP signals uses a method using existing padding or packing technologies. In both cases, a ULE frame is generated by adding a Unidirectional Lightweight Encapsulation (ULE) header and a Cyclic Redundancy Check (CRC) to the MAC frame (excluding the preamble and Frame Check Sequence (FCS)).

[0053] In padding, when a ULE frame is stored in a TS packet, stuffing bytes (0xFF) are written to the remaining bytes of the TS payload, and in packing, the next ULE frame is stored in the remaining bytes.

[0054] The terminal side receiving unit 25 inputs a downlink signal including a monitor video and a control signal from the mobile communication terminal 22-1. Then, the terminal side receiving unit 25 extracts the monitor video etc. from the downlink signal and outputs the monitor video etc. to the video compression decoding unit 27. The terminal side receiving unit 25 also extracts the control signal from the downlink signal and outputs the control signal to the terminal control unit 26.

[0055] The video compression decoding unit 27 inputs monitor video and the like from the terminal side receiving unit 25, compresses and decodes the monitor video in response to the compression encoding by the video compression encoding unit 40 of the base station side transmission device 3-1 shown in Figure 4 described later, and outputs the compressed and decoded monitor video.

[0056] The terminal control unit 26 inputs a control signal from the terminal side receiving unit 25, extracts from the control signal the output bit rate, resolution, etc., which are data on the encoding method used in the video compression encoding unit 23, and outputs the output bit rate, resolution, etc. to the encoding control unit 28.

[0057] Furthermore, the terminal control unit 26 extracts TDD allocation information, the slot ratio and modulation method of the TDD method, etc. from the control signal, generates terminal control information including these, and outputs the terminal control information to the mobile communication terminal 22-1.

[0058] The encoding control unit 28 receives the output bit rate, resolution, etc. from the terminal control unit 26 , generates upstream encoding control information consisting of the output bit rate, resolution, etc., and outputs the upstream encoding control information to the video compression encoding unit 23 .

[0059] (Base station side transmission device 3 / Example 1) Next, a description will be given of the base station side transmission device 3 provided in the video transmission system 1 of the embodiment 1. Fig. 4 is a block diagram showing an example of the configuration of the base station side transmission device 3 in the video transmission system 1 of the embodiment 1.

[0060] The base station side transmission device 3-1 includes a base station side transmitting / receiving unit 30-1, which includes an FPU receiving unit 31, an FPU side buffer 32, a mobile transmitting / receiving unit 33-1, a mobile side buffer 34, a receiver 35, a video compression decoding unit 36, a downlink signal generating unit 37, a base station control unit 38, an encoding control unit 39, and a video compression encoding unit 40.

[0061] The FPU receiving unit 31 receives an uplink signal from the terminal-side transmission device 2-1 via the FPU line 4. Then, the FPU receiving unit 31 performs reception processing on the uplink signal based on a predetermined modulation method or the like for FPU video transmission, extracts an IP signal from the uplink signal, and stores the IP signal in the FPU-side buffer 32 on a packet-by-packet basis.

[0062] The FPU side buffer 32 has a buffer time t b The FPU receiver 31 stores the IP signal in packets. The buffer time t b is the buffering time from when the IP signal is stored in the FPU side buffer 32 until it is output to the receiver 35, that is, the delay time in the FPU side buffer 32. b is preset by an initial process, and then the arrival delay time PD is added to achieve synchronization of the IP signals from the FPU line 4 and the mobile communication line 5.

[0063] The FPU side buffer 32 stores the IP signal for a buffer time t b After the lapse of time, the FPU-side buffer 32 outputs the IP signal to the receiver 35. In other words, the FPU-side buffer 32 stores a packet of the IP signal, and outputs the packet to the receiver 35 for a buffer time t b When the time has elapsed, the packet is output to the receiver 35.

[0064] As a result, the IP signal including the video transmitted from the FPU 21 via the FPU line 4 is buffered in the FPU side buffer 32 for a buffer time t b After a period of time has elapsed, it is input to the receiver 35 .

[0065] The FPU side buffer 32 receives the arrival delay time PD from the receiver 35 and stores the buffer time t b By adding the arrival delay time PD to the buffer time t b The receiver 35 updates the buffer time t b By adding the arrival delay time PD to the buffer time t b may be updated.

[0066] The mobile transmitting / receiving unit 33-1 receives an uplink signal from the terminal-side transmission device 2-1 via the mobile communication line 5. The mobile transmitting / receiving unit 33-1 also inputs a compressed and encoded monitor video from the video compression encoding unit 40, and also inputs a control signal from the base station control unit 38, including TDD allocation information, a slot ratio and a modulation method of the TDD method, and an output bit rate, resolution, and the like for generating uplink encoding control information.

[0067] The mobile transmitting / receiving unit 33-1 performs transmission processing on the input monitor video and control signal based on TDD allocation information, slot ratio and modulation method of the TDD method, etc., contained in the control signal for transmitting video in mobile communication, and generates a downlink signal including the monitor video and the control signal. The mobile transmitting / receiving unit 33-1 then transmits the downlink signal to the terminal-side transmission device 2-1 via the mobile communication line 5.

[0068] The mobile transceiver 33-1 performs reception processing on the received uplink signal based on the TDD allocation information, the slot ratio and modulation method of the TDD method, etc., contained in the control signal for video transmission in mobile communications, extracts the IP signal from the uplink signal, and stores the IP signal in packet units in the mobile-side buffer 34.

[0069] The mobile side buffer 34 stores the buffer time t mb The mobile transceiver 33-1 stores the IP signal in packets. The buffer time t mbis the buffering time from when the IP signal is stored in the mobile buffer 34 until it is output to the receiver 35, that is, the delay time in the mobile buffer 34. mb is preset by an initial process, and then the arrival delay time PD is added to achieve synchronization of the IP signals from the FPU line 4 and the mobile communication line 5.

[0070] The mobile side buffer 34 stores the IP signal for a buffer time t mb After the lapse of time, the mobile-side buffer 34 outputs the IP signal to the receiver 35. That is, the mobile-side buffer 34 stores the packet of the IP signal, and outputs the packet to the receiver 35 after the buffer time t mb When the time has elapsed, the packet is output to the receiver 35.

[0071] As a result, the IP signal including the video transmitted from the mobile communication terminal 22-1 via the mobile communication line 5 is stored in the mobile side buffer 34 for a buffer time t mb After a period of time has elapsed, it is input to the receiver 35 .

[0072] The mobile side buffer 34 receives the arrival delay time PD from the receiver 35 and stores the buffer time t mb By adding the arrival delay time PD to the buffer time t mb The receiver 35 updates the buffer time t mb By adding the arrival delay time PD to the buffer time t mb may be updated.

[0073] The receiver 35 is a device conforming to SMPTE 2022 and includes a switch. The receiver 35 inputs an IP signal from the FPU-side buffer 32 and also inputs an IP signal from the mobile-side buffer 34. The receiver 35 synchronizes the two input IP signals by performing switching processing, input / output processing, and synchronization processing, which will be described later, converts one of the IP signals into a TS signal, and outputs the TS signal to the video compression decoding unit 36.

[0074] Normally, the IP signal input from FPU-side buffer 32 is converted to a TS signal and output. If there is a loss in the IP signal input from FPU-side buffer 32, it is switched to the IP signal input from mobile-side buffer 34, and this IP signal is converted to a TS signal and output.

[0075] In order to synchronize the IP signal input from the FPU side buffer 32 and the IP signal input from the mobile side buffer 34, the arrival delay time PD of both IP signals is measured, and the arrival delay time PD is output to the FPU side buffer 32 or the mobile side buffer 34, whichever arrives first. This results in a buffer time t b or buffer time t mb The arrival delay time PD is added to the

[0076] 5 is a flowchart showing an example of a switching process by the receiver 35. The receiver 35 receives an IP signal from the FPU-side buffer 32, and determines whether or not any packet constituting the IP signal is missing, packet by packet (step S501).

[0077] If receiver 35 determines in step S501 that there is no loss in the IP signal from FPU-side buffer 32 (step S501: N), receiver 35 sets the input / output of the switch to switch to FPU-side buffer 32 (step S502).

[0078] On the other hand, if receiver 35 determines in step S501 that there is a loss in the IP signal from FPU-side buffer 32 (step S501: Y), it sets the input / output of the switch to switch to mobile-side buffer 34 (step S503).

[0079] As a result, if there is no loss of IP signals from FPU-side buffer 32, that is, if uplink signals are being transmitted correctly via FPU line 4, the setting for switching to FPU-side buffer 32 will continue. On the other hand, if there is a loss of IP signals from FPU-side buffer 32, that is, if uplink signals are not being transmitted correctly via FPU line 4, the setting for switching to mobile-side buffer 34 will be made.

[0080] 6 is a flowchart showing an example of input / output processing and synchronization processing by the receiver 35. The receiver 35 inputs an IP signal from the FPU-side buffer 32 (step S601) and also inputs an IP signal from the mobile-side buffer 34 (step S602).

[0081] The receiver 35 measures the packet arrival delay time PD for the same packet of the input two systems of IP signals (step S603). For example, the receiver 35 measures the arrival delay time PD, which is the difference between the arrival times, by subtracting the arrival time indicating the timing at which the same packet of the IP signal was input from the mobile side buffer 34 from the arrival time indicating the timing at which the packet of the IP signal was input from the FPU side buffer 32.

[0082] The receiver 35 determines whether the arrival delay time PD is 0 (step S604).

[0083] When it is determined in step S604 that the arrival delay time PD is 0 (step S604: Y), the receiver 35 determines that the two input IP signals are synchronized.

[0084] Then, receiver 35 converts the IP signal from FPU side buffer 32 or mobile side buffer 34 indicated by the switching setting shown in FIG. 5 into a TS signal (step S605), and outputs the TS signal to video compression decoding unit 36 ​​(step S606).

[0085] On the other hand, when it is determined in step S604 that the arrival delay time PD is not 0 (step S604: N), the receiver 35 determines that the two input IP signals are not synchronized.

[0086] Then, receiver 35 identifies the buffer (FPU side buffer 32 or mobile side buffer 34) in which the packet of the IP signal arrives earlier (earlier input timing) based on arrival delay time PD (step S607).

[0087] For example, assume that the arrival delay time PD measured in step S603 is the time obtained by subtracting the arrival time of the IP signal packet from the mobile side buffer 34 from the arrival time of the IP signal packet from the FPU side buffer 32.

[0088] In this case, if the arrival delay time PD is a negative value, in step S607, the FPU side buffer 32 is identified as the buffer where the IP signal packet arrives earlier. On the other hand, if the arrival delay time PD is a positive value, in step S607, the mobile side buffer 34 is identified as the buffer where the IP signal packet arrives earlier.

[0089] The receiver 35 outputs the arrival delay time PD to the FPU side buffer 32 or the mobile side buffer 34, whichever has the earlier arrival time determined in step S607, so that the arrival delay time PD is equal to or shorter than the buffer time t b or buffer time t mb (step S608).

[0090] As a result, the buffer time t b and the buffer time t mb is determined by the arrival delay time PD.

[0091] In addition, since the arrival delay time PD is added to the buffer time of the buffer where the IP signal arrives earlier, the time (retention time, delay time) between when the IP signal is stored in the earlier buffer and when it is output can be lengthened. Then, the output timing of the IP signal can be synchronized with the output timing of the IP signal stored in the later buffer.

[0092] Therefore, the two systems of IP signals input to the receiver 35 can be synchronized, and as a result, even if the switch provided in the receiver 35 is switched, an IP signal consisting of packets in a consecutive order can be obtained before and after the switch, and the image will not be distorted.

[0093] Returning to FIG. 4, the downlink signal generation unit 37 inputs video and other data, generates various data that constitute the downlink signal, and outputs the input video as a monitor video and a control signal to the base station control unit 38.

[0094] The base station control unit 38 inputs the monitor video and the control signal from the downlink signal generating unit 37. Then, the base station control unit 38 extracts, from the control signal, the output bit rate, resolution, etc. (which are data of the encoding method used in the video compression encoding unit 40 and the video compression encoding unit 23) for generating downlink encoding control information and uplink encoding control information, and also extracts TDD allocation information, the slot ratio and modulation method of the TDD method, etc.

[0095] The base station control unit 38 outputs the monitor video, and the output bit rate, resolution, etc. for generating downlink coding control information to the coding control unit 39. The base station control unit 38 also outputs TDD allocation information, the slot ratio and modulation method of the TDD method, and the output bit rate, resolution, etc. for generating uplink coding control information to the mobile transceiver unit 33-1.

[0096] The encoding control unit 39 inputs the monitor video, output bit rate, resolution, etc. from the base station control unit 38, generates downstream encoding control information consisting of the output bit rate, resolution, etc., and outputs the monitor video and the downstream encoding control information to the video compression encoding unit 40.

[0097] The video compression coding unit 40 inputs the monitor video and downstream coding control information from the coding control unit 39, and compresses and codes the monitor video based on the downstream coding control information to generate a compressed and coded monitor video. The video compression coding unit 40 outputs the compressed and coded monitor video to the mobile transceiver unit 33-1.

[0098] As described above, according to the video transmission system 1 of the first embodiment, the FPU 21 of the terminal side transmission device 2-1 transmits an uplink signal of an IP signal including compressed and encoded video to the base station side transmission device 3-1 via the FPU line 4, and the mobile communication terminal 22-1 transmits an uplink signal of an IP signal including the same compressed and encoded video to the base station side transmission device 3-1 via the mobile communication line 5.

[0099] The FPU receiving unit 31 of the base station side transmission device 3-1 receives the uplink signal via the FPU line 4, extracts the IP signal from the uplink signal, and stores it in the FPU side buffer 32. The FPU side buffer 32 stores the IP signal in the buffer time t b Then it outputs an IP signal.

[0100] The mobile transceiver 33-1 receives an uplink signal via the mobile communication line 5, extracts an IP signal from the uplink signal, and stores the IP signal in the mobile buffer 34. The mobile buffer 34 stores the IP signal in the mobile buffer 34 for a buffer time t mb Then it outputs an IP signal.

[0101] Receiver 35 inputs the IP signals from FPU side buffer 32 and mobile side buffer 34, and, unless there is a loss in the IP signal from FPU side buffer 32, outputs the IP signal to video compression decoding unit 36 ​​for compression-decoding and output as a main broadcast. On the other hand, if there is a loss in the IP signal from FPU side buffer 32, receiver 35 outputs the IP signal from mobile side buffer 34 to video compression decoding unit 36 ​​for compression-decoding and output as a main broadcast.

[0102] As a result, if any part of the video transmitted via the FPU line 4 is missing, the missing part can be supplemented by using the video transmitted via the mobile communication line 5. Therefore, by correcting reception errors that occur in the base station side transmission device 3-1 when wirelessly transmitting a video signal using the FPU 21, the stability of video transmission can be improved without disrupting the main broadcast line.

[0103] In addition, the receiver 35 measures the arrival delay time PD of the same packet for the IP signal from the FPU side buffer 32 and the mobile side buffer 34, identifies the buffer with the earlier arrival time, and outputs the arrival delay time PD to the earlier buffer, thereby obtaining the buffer time t b or buffer time t mb is updated by adding the arrival delay time PD to

[0104] This allows the delay time difference in the wireless sections of the FPU line 4 and the mobile communication line 5 to approach zero by adjusting the delay time between the paths of both IP signals. In other words, the timing of the IP signal output from the buffer where the packet arrives earlier can be delayed to match the timing of the IP signal output from the buffer where the same packet arrives later. In this case, the same packet will be input at the same time to the receiver 35, and both IP signals will be synchronized.

[0105] Therefore, if a loss occurs in the video transmitted via the FPU line 4, the loss can be compensated for using synchronized video transmitted via the mobile communication line 5, making it possible to switch without interruption and reliably improving the stability of video transmission.

[0106] Example 2 Next, a detailed description will be given of Example 2. As described above, Example 2 further improves the stability of video transmission by performing retransmission request processing for mobile communication in addition to the processing of Example 1.

[0107] (Terminal side transmission device 2 / Example 2) First, a description will be given of a terminal-side transmission device 2 provided in a video transmission system 1 of Example 2. Fig. 7 is a block diagram showing a configuration example of the terminal-side transmission device 2 in the video transmission system 1 of Example 2. This terminal-side transmission device 2-2 includes a terminal-side transceiver unit 20, an FPU 21, a mobile communication terminal 22-2, and a mobile processing unit 50.

[0108] Comparing the terminal-side transmission device 2-1 in the first embodiment shown in Fig. 2 with the terminal-side transmission device 2-2 in the second embodiment shown in Fig. 7, both the terminal-side transmission devices 2-1 and 2-2 have in common the point that they are provided with a terminal-side transceiver unit 20 and an FPU 21. On the other hand, the terminal-side transmission device 2-2 is different from the terminal-side transmission device 2-1 in that it is provided with a mobile communication terminal 22-2 different from the mobile communication terminal 22-1, and further includes a mobile processing unit 50.

[0109] In Fig. 7, parts common to Fig. 2 are given the same reference numerals as in Fig. 2, and detailed description thereof will be omitted. Here, the terminal side transmitting / receiving unit 20 generates an IP signal including video consisting of two systems of identical packets, similar to the first embodiment shown in Fig. 2. Then, the terminal side transmitting / receiving unit 20 outputs one IP signal to the FPU 21, and outputs the other IP signal to the mobile processing unit 50.

[0110] The mobile communication terminal 22-2 performs the same processing as the mobile communication terminal 22-1 in the embodiment 1 shown in FIG. 2, and further, when a retransmission request is included in the downlink signal received from the base station side transmission device 3-2 described later, the mobile communication terminal 22-2 extracts the retransmission request from the downlink signal and outputs the retransmission request to the mobile processing unit 50.

[0111] The mobile communication terminal 22-2 may output a downlink signal including a retransmission request to the terminal-side transceiver 20 without extracting the retransmission request from the downlink signal. In this case, the terminal-side transceiver 20 (the terminal control unit 26) extracts the retransmission request from the downlink signal and outputs it to the mobile processing unit 50.

[0112] The retransmission request includes the packet number of the IP signal corresponding to the missing portion in one frame of video.

[0113] The mobile processing unit 50 receives an IP signal including video (the same signal as the IP signal received by the FPU 21) from the terminal side transmitting / receiving unit 20, and outputs the IP signal to the mobile communication terminal 22-2 according to the switching setting of the switch 52 described later.

[0114] Furthermore, mobile processing unit 50 stores the input IP signal in retransmission buffer 53, which will be described later, and when a retransmission request is input from mobile communication terminal 22-2, outputs the IP signal corresponding to the retransmission request stored in retransmission buffer 53 to mobile communication terminal 22-2 in accordance with the switching setting of switch 52, which will be described later. The IP signal corresponding to the retransmission request is retransmitted from mobile communication terminal 22-2.

[0115] (Mobile Processing Unit 50) Fig. 8 is a block diagram showing an example of the configuration of the mobile processing unit 50, and Fig. 9 is a flowchart showing an example of the processing of the mobile processing unit 50. This mobile processing unit 50 includes a distributor 51, a switch 52, and a retransmission buffer 53.

[0116] The switch 52 sets the input / output initial setting to switch to the distributor 51 (step S901). The distributor 51 inputs an IP signal from the terminal-side transmitting / receiving unit 20 (step S902), distributes the IP signal into two systems of IP signals consisting of the same packets, outputs one IP signal to the switch 52, and stores the other IP signal in the retransmission buffer 53 (step S903).

[0117] As a result, an IP signal consisting of a group of IP packets storing the same video is input to the switch 52 and stored in the retransmission buffer 53 .

[0118] The retransmission buffer 53 has a buffer time t mb2 The IP signal is stored in packets by the distributor 51. The buffer time t mb2 is the buffering time from when the IP signal is stored in the retransmission buffer 53 until it is output to the switch 52, that is, the delay time in the retransmission buffer 53. mb2 is the mobile video uplink time t mu The retransmission downlink time t md The time is set based on the result of adding the above, and is preset by the initial processing, or is set to a time calculated by the mobile communication terminal 22-2.

[0119] The retransmission buffer 53 stores the IP signal for a buffer time t mb2 After the lapse of the buffer time t, the retransmission buffer 53 outputs the IP signal to the switch 52. mb2 When the time has elapsed, the packet is output to the switch 52.

[0120] The switch 52 inputs the IP signal from the distributor 51 and also inputs the IP signal from the retransmission buffer 53. The switch 52 determines whether or not a retransmission request has been input from the mobile communication terminal 22-2 (step S904). If the switch 52 determines in step S904 that a retransmission request has not been input (step S904: N), the switch 52 outputs the IP signal from the distributor 51 indicated by the switching setting in step S901 or step S908 described later to the mobile communication terminal 22-2 (step S905).

[0121] On the other hand, when it is determined in step S904 that a retransmission request has been input (step S904: Y), the switch 52 switches the input / output setting to the retransmission buffer 53 (step S906). Then, in accordance with the switching setting in step S906, the switch 52 outputs the IP signal from the retransmission buffer 53 indicated by the switching setting to the mobile communication terminal 22-2 (step S907).

[0122] In step S907, the switch 52 outputs the IP signal of the packet number of the missing portion input from the retransmission buffer 53 to the mobile communication terminal 22-2 (when the output is completed), and then returns the input / output setting to the switching setting for the distributor 51 (step S908).

[0123] (Base station side transmission device 3 / Example 2) Next, a description will be given of the base station side transmission device 3 provided in the video transmission system 1 of the embodiment 2. Fig. 10 is a block diagram showing an example of the configuration of the base station side transmission device 3 in the video transmission system 1 of the embodiment 2.

[0124] The base station side transmission device 3-2 includes a base station side transmitting / receiving unit 30-2. The base station side transmitting / receiving unit 30-2 includes an FPU receiving unit 31, an FPU side buffer 32, a mobile transmitting / receiving unit 33-2, a mobile side buffer 34, a receiver 35, a video compression decoding unit 36, a downlink signal generating unit 37, a base station control unit 38, an encoding control unit 39, and a video compression encoding unit 40.

[0125] Comparing the base station side transmitting / receiving unit 30-1 of the base station side transmission device 3-1 in the first embodiment shown in Fig. 4 with the base station side transmitting / receiving unit 30-2 of the base station side transmission device 3-2 in the second embodiment shown in Fig. 10, both base station side transmitting / receiving units 30-1 and 30-2 are common in that they include an FPU receiving unit 31, an FPU side buffer 32, a mobile side buffer 34, a receiver 35, a video compression decoding unit 36, a downlink signal generating unit 37, a base station control unit 38, an encoding control unit 39, and a video compression encoding unit 40. On the other hand, the base station side transmitting / receiving unit 30-2 is different from the base station side transmitting / receiving unit 30-1 in that it includes a mobile transmitting / receiving unit 33-2 that is different from the mobile transmitting / receiving unit 33-1. In Fig. 10, the parts common to Fig. 4 are given the same reference numerals as in Fig. 4, and detailed explanations thereof will be omitted.

[0126] The mobile transmitting / receiving unit 33-2 performs the same processing as the mobile transmitting / receiving unit 33-1 in the first embodiment shown in FIG. 4, and further performs retransmission request processing.

[0127] 11 is a flowchart showing an example of a retransmission request process by the mobile transmitting / receiving unit 33-2. The mobile transmitting / receiving unit 33-2 receives an uplink signal from the terminal-side transmission device 2-2 via the mobile communication line 5 (step S1101).

[0128] The mobile transmitting / receiving unit 33-2 performs a predetermined receiving process on the received uplink signal and extracts the IP signal from the uplink signal. Then, the mobile transmitting / receiving unit 33-2 determines whether or not any packet constituting the IP signal is missing on a packet-by-packet basis (step S1102).

[0129] If it is determined in step S1102 that there is no loss in the IP signal (step S1102: N), the mobile transmitting / receiving unit 33-2 stores the IP signal in packet units in the mobile side buffer 34 (step S1103).

[0130] On the other hand, if the mobile transceiver 33-2 determines in step S1102 that there is a loss in the IP signal (step S1102: Y), it generates a retransmission request including the packet number of the IP signal of the part of the one frame of video determined to be lost (step S1104).

[0131] The mobile transceiver 33-2 performs a predetermined transmission process in response to the retransmission request, generates a downlink signal including the retransmission request, and transmits the downlink signal to the terminal-side transmission device 2-2 via the mobile communication line 5 (step S1105).

[0132] (Number of slots for transmitting one frame of video in a mobile communication line 5) Next, an example will be given of the number of slots and transmission time when transmitting one frame of video in the mobile communication line 5.

[0133] For example, the video to be transmitted (camera video) is 4K and 60 fps, and is compressed using the H.264 standard. In this case, the video transmission rate is 50 Mbps, and the allowable transmission delay is 16.7 ms, since it is 1 s / 60 fps per frame. Also, the average bit rate per frame is 0.83 Mbps, which is 50 Mbps / 60 fps.

[0134] It is assumed that the transmission rate of the FPU 21 used is 148.3 Mbps, so the time required for the FPU 21 to transmit one frame is 0.83 Mbps / 148.3 Mbps=5.6 ms.

[0135] The mobile communication line 5 is assumed to be a line that complies with local 5G. When MCS22 is selected as the transmission mode, the coding rate is 0.65.

[0136] 12 is a diagram showing an example of slot allocation in the TDD system in a local 5G mobile communication line 5. D is a downlink slot, U is an uplink slot, S is an uplink / downlink switching slot, and the frame time in the TDD system is 10 ms.

[0137] As shown in FIG. 12, when the ratio of the number of downlink slots D (the number of slots of the downlink signal) to the number of uplink slots U (the number of slots of the uplink signal) is 6:12, the transmission rate is 43 Mbps for the downlink signal downlink line and 88 Mbps for the uplink signal uplink line.

[0138] The channel data size per slot is 9222 bytes, and the number of transmission bits per slot is 114048 = 0.114 MB. Therefore, the number of slots in which the uplink signal required to transmit one frame of video is stored is 0.83 Mbps / 0.114 MB, which is 9 (slots).

[0139] In other words, in a local 5G mobile communication line 5, nine slots are required to transmit one frame of video, and as shown in Figure 12, one frame of video can be transmitted in 8.5 ms, which is the section in which the number of upstream slots U counted from the beginning is 9.

[0140] (The buffer time t mb2 ) Next, the buffer time t mb2 As mentioned above, the buffer time t mb2 is the buffering time (delay time) from when the IP signal is stored in the retransmission buffer 53 until it is output, and is the mobile video uplink time t mu The retransmission downlink time t md The value is set based on the result of adding the above.

[0141] Buffer time t mb2 may be set in advance, or may be automatically updated according to the status of the mobile communication line 5 by measuring the transmission and reception timing of the retransmission request in the mobile communication line 5, etc.

[0142] FIG. 13 is a diagram for explaining the timing of retransmission of video. The horizontal axis indicates time. The time period required to transmit one frame of video from the mobile communication terminal 22-2 on the terminal side to the mobile transceiver unit 33-2 on the base station side via the mobile communication line 5 (mobile video uplink time t mu ) is 10ms (t mu = 10 ms). In other words, the mobile video uplink time t mu is the time from the uplink signal transmission time ULTx1 to the uplink signal reception time ULRx1 (the transmission time of one frame of video from the mobile communication terminal 22-2 to the mobile transceiver 33-2).

[0143] Also, the time period required to transmit a retransmission request from the mobile transceiver 33-2 on the base station side to the mobile communication terminal 22-2 on the terminal side via the mobile communication line 5 (retransmission downlink time t md ) is 2ms (t md = 2 ms). That is, the retransmission downlink time t md is the time from the downlink signal transmission time DLTx to the downlink signal reception time DLRx (the transmission time of a retransmission request from the mobile transceiver 33-2 to the mobile communication terminal 22-2).

[0144] It is assumed that the time from when the mobile communication terminal 22-2 transmits one frame of video, receives a retransmission request, and when the switch 52 completes the setting for switching to the retransmission buffer 53 is 13 ms, including the delay time t0 in the terminal-side transmission device 2-2 and the base station-side transmission device 3-2. This time corresponds to the time from the uplink signal transmission time ULTx1 to the switching time α of the retransmission buffer 53. The delay time t0 is sufficiently smaller than the order of ms.

[0145] The time period during which the retransmission video is transmitted in response to the retransmission request (mobile retransmission video uplink time t mu2 ) is 2ms (t mu2 = 2 ms). This retransmission image is the part of one frame of image that was lost. In other words, the mobile retransmission image uplink time t mu2is the time from the uplink signal transmission time ULTx2 to the uplink signal reception time ULRx2 (the transmission time of the video for retransmission from the mobile communication terminal 22-2 to the mobile transceiver 33-2).

[0146] The total time from when mobile communication terminal 22-2 transmits one frame of video, to when it transmits the retransmission video in response to the retransmission request, through storage time β at which the retransmission video is stored in mobile side buffer 34 (storage time β in mobile side buffer 34), to input time γ at receiver 35 at which receiver 35 inputs the retransmission video from mobile side buffer 34, is approximately 15 ms.

[0147] As mentioned above, when the video to be transmitted is 4K and 60 fps and is compressed according to the H.264 standard, the allowable transmission delay time for one frame of video is 16.7 ms.

[0148] Therefore, as shown in FIG. 13, the time period during which the retransmission video is transmitted is determined as the mobile retransmission video uplink time t mu2 = 2 ms, the total time of 15 ms from when one frame of video is transmitted to when the video for retransmission in response to the retransmission request is input to receiver 35 falls within the allowable transmission delay time of 16.7 ms for one frame of video.

[0149] In other words, when the receiver 35 on the base station side determines that an IP signal transmitted from the FPU 21 is missing and inputs the missing video portion from the mobile side buffer 34, even if a retransmission request process is performed on the IP signal of that video portion stored in the mobile side buffer 34, the video to be retransmitted is input from the mobile side buffer 34 to the receiver 35 at an appropriate timing, and as a result, transmission of video at 4K and 60 fps compressed according to the H.264 standard can be realized.

[0150] FIG. 14 shows the buffer time t mb2 As described above, the buffer time t mb2may be set in advance, or may be automatically updated according to the status of the mobile communication line 5 by measuring the transmission and reception timing of the retransmission request. mb2 is set in advance by the user.

[0151] First, the user determines a mobile image uplink time t for transmitting one frame of image based on the number of slots SL for transmitting one frame of image through the mobile communication line 5. mu is set (step S1401).

[0152] In the above example, the number of slots SL=9 for transmitting one frame of video through the mobile communication line 5 is calculated, and the mobile video uplink time t mu =10ms is set.

[0153] Then, the user determines the retransmission downlink time t for transmitting the retransmission request by taking into account the status of the mobile communication line 5 and the size of the image to be retransmitted. md In the above example, the retransmission downlink time t md =2ms is set.

[0154] Then, the user mu Retransmission downlink time t md By adding, time t'(=t mu +t md ) is calculated (step S1403). In the above example, t' (=t mu +t md ) = 12 ms is obtained.

[0155] Then, the user determines the buffer time t of the retransmission buffer 53 based on the time t'. mb2 (Step S1404). In the above example, the buffer time t mb2 =13ms is set.

[0156] In addition, the buffer time t mb2In the case of automatically updating the buffer time t mb2 Calculate the buffer time t mb2 is set in the retransmission buffer 53.

[0157] Specifically, in step S1402, the mobile communication terminal 22-2 receives a downlink signal including a retransmission request to which a transmission time has been added from the mobile transceiver 33-2, and extracts the transmission time of the retransmission request from the downlink signal. Then, the mobile communication terminal 22-2 subtracts the transmission time from the reception time of the downlink signal to obtain the retransmission downlink time t md Set.

[0158] In this case, the mobile transceiver 33-2 adds the transmission time to the retransmission request, and transmits a downlink signal including the retransmission request to the mobile communication terminal 22-2. It is assumed that the transmission time and the reception time are synchronized.

[0159] Then, in step S1403, the mobile communication terminal 22-2 receives the mobile image uplink time t mu In step S1402, the retransmission downlink time t md By adding, time t'(=t mu +t md ) is required.

[0160] In step S1404, the mobile communication terminal 22-2 adds a preset value to the time t' to obtain the buffer time t of the retransmission buffer 53. mb2 Set.

[0161] As described above, according to the video transmission system 1 of the second embodiment, when there is a loss in the IP signal contained in the received uplink signal, the mobile transceiver 33-2 of the base station side transmission device 3-2 generates a retransmission request and transmits a downlink signal including the retransmission request to the mobile communication terminal 22-2 of the terminal side transmission device 2-2 via the mobile communication line 5.

[0162] The mobile processing unit 50 of the terminal side transmission device 2-2 stores the IP signal in the retransmission buffer 53, and when a retransmission request is input from the mobile communication terminal 22-2, it outputs the IP signal corresponding to the retransmission request stored in the retransmission buffer 53 to the mobile communication terminal 22-2, and the mobile communication terminal 22-2 transmits an uplink signal of the IP signal to the mobile transceiver unit 33-2.

[0163] As a result, even if there is a loss of video transmitted from mobile communication terminal 22-2 via mobile communication line 5, the lost video is retransmitted.

[0164] Therefore, in a video transmission system 1 that wirelessly transmits video using an FPU 21, when a reception error that occurs in the base station side transmission device 3-2 is corrected using video transmitted using a mobile communication terminal 22-2, even if there is a loss in the video, the lost video is retransmitted, thereby further improving the stability of the video transmission.

[0165] Although the present invention has been described above with reference to the first and second embodiments, the present invention is not limited to the first and second embodiments, and various modifications are possible without departing from the technical concept thereof. [Explanation of symbols]

[0166] 1. Video transmission system 2-1, 2-2 Terminal side transmission device 3-1, 3-2 Base station transmission equipment 4 FPU lines 5. Mobile communication lines 20 Terminal side transmitting / receiving unit 21 FPU 22-1, 22-2 Mobile communication terminals 23,40 Video compression coding section 24 Transmitter 25 Terminal side receiving section 26 Terminal control unit 27,36 Video compression and decoding section 28,39 Encoding control section 30-1, 30-2 Base station side transceiver 31 FPU receiver 32 FPU side buffer 33-1, 33-2 Mobile transmitter / receiver 34 Mobile side buffer 35 Receiver 37 Downlink signal generator 38 Base Station Control Unit 50 Mobile Processing Department 51 Distributor 52 Switch 53 Retransmission Buffer t b ,t mb ,t mb2 Buffer Time PD Arrival Delay Time D Downstream slot U Up Slot S Upstream / downstream switching slot SL Slot Number t0 Delay Time t md Retransmission Downlink Time t mu Mobile video uplink time t mu2 Mobile retransmission video uplink time ULTx1, ULTx2 uplink signal transmission time ULRx1, ULRx2 uplink signal reception time DLTx Downlink signal transmission time DLRx Downlink signal reception time α Switching time of retransmission buffer 53 β Storage time of mobile side buffer 34 γ Receiver 35 input time

Claims

1. In a video transmission system in which video is wirelessly transmitted from a field pickup unit (FPU: portable wireless transmission device) provided in a terminal-side transmission device to a base station-side transmission device, The terminal side transmission device a terminal-side transceiver unit which inputs a camera image and a control signal included in a downlink signal transmitted from the base station-side transmission device, compresses and encodes the camera image based on the control signal to generate a TS signal, converts the TS signal into an IP signal, and outputs the IP signal consisting of two systems of identical packets as a first IP signal and a second IP signal; the FPU that receives the first IP signal output by the terminal-side transceiver, generates a first uplink signal including the first IP signal, and transmits the first uplink signal to the base station-side transmission device via a wireless line; a mobile communication terminal that receives the second IP signal output by the terminal-side transceiver unit, generates a second uplink signal including the second IP signal, transmits the second uplink signal to the base station-side transmission device via a wireless line of mobile communication, and receives the downlink signal including the control signal from the base station-side transmission device via the wireless line of mobile communication, The base station side transmission device an FPU receiving unit that receives the first uplink signal from the FPU via the wireless line and stores the first IP signal included in the first uplink signal in an FPU-side buffer; a mobile transceiver unit that receives the second uplink signal from the mobile communication terminal via the wireless line of the mobile communication, stores the second IP signal included in the second uplink signal in a mobile side buffer, generates the downlink signal including the control signal, and transmits the downlink signal to the mobile communication terminal via the wireless line of the mobile communication; inputting the first IP signal from the FPU-side buffer and the second IP signal from the mobile-side buffer, and determining whether or not there is a loss in the first IP signal; a receiver that outputs the first IP signal input from the FPU side buffer when it is determined that there is no loss, and outputs the second IP signal input from the mobile side buffer for compensating for the loss when it is determined that there is a loss; a video compression decoding unit that performs compression decoding corresponding to the compression encoding by the terminal side transceiver unit on the video contained in the first IP signal or the second IP signal output by the receiver, thereby generating and outputting main broadcast video.

2. 2. The video transmission system according to claim 1, The FPU side buffer provided in the base station side transmission device includes: The first IP signal is stored in packets, and a buffer time t b outputting the first IP signal in units of packets when time has elapsed; The mobile side buffer provided in the base station side transmission device, The second IP signal is stored in packets, and a buffer time t mb outputting the second IP signal in units of packets when time has elapsed; The receiver provided in the base station side transmission device, Measure an arrival delay time PD indicating a difference in time when the same packet is input for the first IP signal input from the FPU side buffer and the second IP signal input from the mobile side buffer; If the arrival delay time PD is not 0, the IP signal that is input earlier in the same packet is identified based on the arrival delay time PD, and the buffer time t b or the buffer time t mb The buffer time t b or the buffer time t mb Update, 2. A video transmission system comprising: a video transmission unit configured to transmit a first IP signal or a second IP signal when the arrival delay time PD is 0;

3. 3. The video transmission system according to claim 1, The terminal-side transmission device further includes a mobile processing unit, The mobile transceiver unit provided in the base station side transmission device, determining whether or not there is a loss in the second IP signal included in the second uplink signal, and if it is determined that there is no loss, storing the second IP signal in the mobile side buffer, and if it is determined that there is a loss, generating the downlink signal including a retransmission request, and transmitting the downlink signal to the mobile communication terminal; The mobile communication terminal provided in the terminal side transmission device, receiving the downlink signal from the mobile transceiver unit, and outputting the retransmission request included in the downlink signal to the mobile processing unit; The mobile processing unit provided in the terminal side transmission device, inputting the second IP signal output by the terminal side transmitting / receiving unit, and storing the second IP signal in a retransmission buffer; If the retransmission request is not received from the mobile communication terminal, the second IP signal is output to the mobile communication terminal. when the retransmission request is input from the mobile communication terminal, the second IP signal is input from the retransmission buffer, and the second IP signal is output to the mobile communication terminal; The mobile communication terminal provided in the terminal side transmission device, a second IP signal input from the mobile processing unit, and a second uplink signal is generated and transmitted to the base station side transmission device.

Images