Video display system and video display method

Abstract

To suppress variation in video delay.SOLUTION: A reception unit includes: a data reception part; a video data buffer part; a display device for displaying a video based on video data; a blinking detection part for detecting blinking of marker light in the video displayed on the display device; a reception side reference signal transmission part for transmitting a reception side reference signal synchronized with a reference synchronization signal at a remote location; a delay time calculation part for calculating a delay time from a time when the video is captured by an imaging device until a time when the video is displayed on the display device, based on a blinking signal indicating a blinking state of the detected marker light and the reception side reference signal; a preset delay time acquisition part for acquiring a predetermined preset delay time based on the delay time calculated by the delay time calculation part; and a video data output part for delaying the video data stored in the video data buffer part based on the preset delay time acquired by the preset delay time acquisition part, and outputting it.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a video display system and a video display method.

Background Art

[0002] When displaying a captured video on a display device provided at a remote location away from the shooting location, a time delay occurs between the shooting and the display of the video. This time delay is caused by the time required for encoding the captured video data, transmitting the encoded video data, transmitting the video data over a network, receiving the video data at the display device, decoding the received video data, and displaying the video based on the decoded video data, etc.

[0003] On the other hand, Patent Document 1 discloses a video transmission time measurement system including a blinking marker arranged at an imaging location, an imaging location clock timer arranged at the imaging location, a light receiving sensor that detects the blinking of the blinking marker projected and displayed by a video projection device arranged at a projection location, a projection location clock timer arranged at the projection location and synchronized with the imaging location clock timer, and a measurement camera arranged at the projection location that captures the video projected and displayed by the video projection device and the projection location clock timer side by side. In this video transmission time measurement system, the imaging location clock timer and the blinking marker are captured together by an imaging video camera, and the captured video is projected and displayed by the video projection device. Further, the video of the imaging location clock timer projected and displayed and the projection location clock timer whose clock time display is fixed according to the output from the light receiving sensor are simultaneously captured by the measurement camera, and the video transmission time is determined by reading the clock times of both clock timers from the captured video.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the configuration described in Patent Document 1, for example, due to the communication environment or the like between the imaging location and the projection location, the delay time until the sequentially captured video is displayed may vary. For example, when operating a vehicle, a ship, various devices, etc. while viewing the video captured at the imaging location at the projection location, if the delay time of the video displayed at the projection location varies, the operator may feel discomfort.

[0006] The present disclosure has been made to solve the above problems, and an object thereof is to provide a video display system and a video display method capable of suppressing variations in video delay.

Means for Solving the Problems

[0007] To solve the above problems, a video display system according to the present disclosure includes a transmission unit disposed at a shooting location and a reception unit installed at a separation location away from the shooting location. The transmission unit includes a blinking marker that periodically blinks marker light based on a reference synchronization signal at the shooting location, a shooting device that shoots a video including a shooting target and the blinking marker at the shooting location, and a data transmission unit that transmits data of the video shot by the shooting device via a wireless communication network. The reception unit includes a data reception unit that receives the data of the video via the wireless communication network, a video data buffer unit that temporarily stores the data of the video received by the data reception unit, a display device that displays a video based on the received data of the video, a blinking detection unit that detects blinking of the marker light in the video displayed on the display device, a reception-side reference signal transmission unit that transmits a reception-side reference signal synchronized with the reference synchronization signal at the separation location, a delay time calculation unit that calculates a delay time from when the video is shot by the shooting device until it is displayed on the display device based on a blinking signal indicating the blinking state of the marker light detected by the blinking detection unit and the reception-side reference signal, a set delay time acquisition unit that acquires a preset set delay time based on the delay time calculated by the delay time calculation unit, and a video data output unit that delays and outputs the data of the video stored in the video data buffer unit based on the set delay time acquired by the set delay time acquisition unit.

[0008] The video display method according to the present disclosure includes: periodically flashing marker light based on a reference synchronization signal at a shooting location; shooting a video including a shooting target and the flashing marker at the shooting location; transmitting data of the shot video via a wireless communication network; receiving the data of the video via the wireless communication network; temporarily storing the received data of the video; displaying a video based on the received data of the video at a separation location away from the shooting location; detecting the flashing of the marker light in the displayed video; transmitting a reception-side reference signal synchronized with the reference synchronization signal at a separation location away from the shooting location; calculating a delay time from when the video was shot at the shooting location to when it is displayed at the separation location based on the detected flashing signal indicating the flashing state of the marker light and the reception-side reference signal; obtaining a preset set delay time based on the calculated delay time; and delaying and outputting the temporarily stored data of the video based on the set delay time.

Effect of the Invention

[0009] According to the video display system and video display method of the present disclosure, variations in video delay can be suppressed.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Mode for Carrying Out the Invention

[0011] Hereinafter, with reference to the accompanying drawings, embodiments for implementing a video display system and a video display method according to the present disclosure will be described. However, the present disclosure is not limited to only this embodiment. (Configuration of Video Display System) As shown in FIG. 1, the video display system 1 includes a transmission unit 2 disposed at a shooting location and a reception unit 5 installed at a separated location away from the shooting location. In an embodiment of the present disclosure, the video display system 1 is installed, for example, in a vehicle mounting space 102s on a vehicle deck 102 provided inside a hull of a ship 100 such as a ferry. A plurality of vehicle compartments 105 are provided on the vehicle deck 102. Vehicles C such as trailers, trucks, and passenger cars transported by the ship 100 are parked in each vehicle compartment 105 by the driving of the driver of the vehicle.

[0012] The transmission unit 2 of the video display system 1 uses the imaging device 3 described later to image each vehicle section 105, and transmits a video showing the position of vehicle C with respect to the vehicle section 105 to the reception unit 5. The reception unit 5 of the video display system 1 is mounted on vehicle C that intends to park in the vehicle section 105, and displays the video transmitted from the transmission unit 2. Thereby, the driver of vehicle C parks at an appropriate position with respect to a predetermined vehicle section 105 while viewing the video displayed on the reception unit 5.

[0013] (Configuration of the transmission unit) The transmission unit 2 is arranged at an imaging location where the vehicle section 105 as the imaging target T can be imaged. As shown in FIG. 2, the transmission unit 2 may be provided on the ceiling 106 or the like above each vehicle section 105. The transmission unit 2 includes an imaging device 3, a blinking marker 4, and a transmission-side controller 20 (see FIG. 3). The imaging device 3 images a video including the imaging target T and the blinking marker 4 at the imaging location.

[0014] The blinking marker 4 is arranged within the range that can be imaged by the imaging device 3. As the blinking marker 4, an LED (Light Emitting Diode) can be exemplified. The blinking marker 4 periodically blinks the marker light at a predetermined blinking cycle under the control of the transmission-side controller 20. The imaging device 3 images the blinking state of the marker light of the blinking marker 4.

[0015] As shown in FIG. 3, the transmission-side controller 20 can be configured using a computer such as a microcomputer and a CPU (Central Processing Unit), and hardware such as peripheral circuits and peripheral devices of the computer. In the present embodiment, the transmission-side controller 20 is configured by a control board on which a microcomputer is mounted. The transmission-side controller 20 includes a blinking control unit 22, a transmission-side synchronization signal reception unit 23, and a data transmission unit 25 as a functional configuration composed of a combination of hardware and software such as a program executed by the computer.

[0016] The transmission-side synchronization signal receiving unit 23 receives a reference synchronization signal transmitted from the outside. The transmission-side synchronization signal receiving unit 23 is, for example, a wireless modem in terms of hardware. The reference synchronization signal is transmitted from a master unit 9 described later.

[0017] The blinking control unit 22 controls the blinking operation of the blinking marker 4. The blinking control unit 22 includes, for example, a crystal oscillator 221, a frequency division circuit 222, and an integration counter unit 223. The crystal oscillator 221 transmits a highly accurate reference clock signal with a predetermined frequency. As an example of the frequency of the reference clock signal transmitted by the crystal oscillator 221, 12.8 MHz can be cited. The frequency division circuit 222 divides the signal with a predetermined frequency input from the crystal oscillator 221 and generates a pulse signal with a preset frequency. In the embodiment of the present disclosure, the frequency division circuit 222 generates, for example, a pulse signal with a frequency of 1 kHz. Further, when the reference synchronization signal received by the transmission-side synchronization signal receiving unit 23 is input, the frequency division circuit 222 resets the pulse signal based on the input reference synchronization signal. The integration counter unit 223 counts the number of pulses based on the pulse signal generated by the frequency division circuit 222 and outputs the count value to the blinking marker 4. The blinking marker 4 blinks the marker light at a preset time interval based on the count value output from the integration counter unit 223.

[0018] The data transmission unit 25 transmits the data of the video captured by the imaging device 3. In the embodiment of the present disclosure, the data transmission unit 25 transmits the data of the video including the vehicle section 105, which is the imaging target T, and the blinking marker 4 captured by the imaging device 3. Also, when other communications such as communication between other transmission units 2 and reception units 5 are being performed via the wireless communication network N, the data transmission unit 25 does not transmit video data. The data transmission unit 25 transmits the video data captured by the imaging device 3 via the wireless communication network N only when no other communication is being performed via the wireless communication network N. When other communication has been performed via the wireless communication network N, the data transmission unit 25 re-checks the communication state of the wireless communication network N after a preset predetermined waiting time has elapsed, and after confirming that no other communication is being performed, transmits the video data.

[0019] (Configuration of the reception unit) The reception unit 5 is configured to be capable of data communication with the transmission unit 2 via various wireless communication networks N such as Wi-Fi and a public wireless telephone communication network. The reception unit 5 includes a reception-side controller 50, a display device 6, a blinking detection unit 7, and a video display device 8.

[0020] The reception-side controller 50 can be configured using a computer such as a microcomputer and a CPU (Central Processing Unit), and hardware such as peripheral circuits and peripheral devices of the computer. In the present embodiment, the reception-side controller 50 is configured by a control board equipped with a microcomputer. The reception-side controller 50, as a functional configuration composed of a combination of hardware and software such as a program executed by the computer, includes a data reception unit 51, a video data buffer unit 52, a reception-side synchronization signal reception unit 53, a blinking control unit 54, a reception-side reference signal transmission unit 55, a delay time calculation unit 56, a set delay time acquisition unit 57, and a video data output unit 58.

[0021] The data reception unit 51 receives the video data transmitted from the data transmission unit 25 via the wireless communication network N. The video data buffer unit 52 temporarily stores the video data received by the data reception unit 51.

[0022] The receiving - side synchronization signal receiving unit 53 receives a reference synchronization signal from the outside, similar to the transmitting - side synchronization signal receiving unit 23. The receiving - side synchronization signal receiving unit 53 is, in terms of hardware, for example, a wireless modem. The reference synchronization signal is transmitted from a master unit 9 described later.

[0023] The blinking control unit 54 includes, for example, a crystal oscillator 541, a frequency - dividing circuit 542, and an integration counter unit 543. The crystal oscillator 541 transmits a highly accurate reference clock signal with the same frequency as the crystal oscillator 221. The frequency - dividing circuit 542 divides the signal with a predetermined frequency input from the crystal oscillator 541 and generates a pulse signal with the same frequency as the frequency - dividing circuit 222. When the reference synchronization signal received by the receiving - side synchronization signal receiving unit 53 is input, the frequency - dividing circuit 542 resets the pulse signal based on the input reference synchronization signal. The integration counter unit 543 counts the number of the pulse signals generated by the frequency - dividing circuit 542 and outputs the count value to the receiving - side reference signal transmitting unit 55.

[0024] The receiving - side reference signal transmitting unit 55 transmits a receiving - side reference signal synchronized with the reference synchronization signal based on the count value output from the integration counter unit 543. The receiving - side reference signal transmitting unit 55 may include a blinking marker 59. When the receiving - side reference signal transmitting unit 55 includes the blinking marker 59, the receiving - side reference signal transmitting unit 55 blinks the marker light of the blinking marker 59 at a preset time interval based on the receiving - side reference signal. In the embodiment of the present disclosure, the receiving - side reference signal transmitting unit 55 does not include the blinking marker 59 and transmits the same receiving - side reference signal as the case where the blinking marker 59 blinks.

[0025] The display device 6 displays an image based on the data received by the data receiving unit 51. The image displayed on the display device 6 includes the images of the imaging target T and the blinking marker 4 photographed by the imaging device 3. The image displayed on the display device 6 may display only the image of the part of the blinking marker 4 among the images photographed by the imaging device 3.

[0026] The flashing detection unit 7 detects the flashing of the marker light of the flashing marker 4 in the video displayed on the display device 6. As the flashing detection unit 7, a photodiode can be exemplified. The flashing detection unit 7 is fixed in accordance with the position of the marker light of the flashing marker 4 in the video displayed on the display device 6. The flashing detection unit 7 detects the flashing state (lighting or extinguishing) of the marker light. The flashing detection unit 7 outputs a flashing signal indicating the flashing state of the marker light to the delay time calculation unit 56. The flashing signal is a waveform signal indicating the switching of the signal state according to the lighting and extinguishing of the flashing marker 4. This flashing signal includes a delay time with respect to the timing at which the flashing marker 4 of the transmission unit 2 flashes the marker light based on the reference synchronization signal. The delay time of the flashing signal with respect to the timing at which the flashing marker 4 flashes the marker light coincides with the video transmission delay time until the video captured by the imaging device 3 is displayed on the display device 6.

[0027] The delay time calculation unit 56 calculates the delay time from when the video is captured by the imaging device 3 until it is displayed on the display device 6 based on the flashing signal indicating the flashing state of the marker light detected by the flashing detection unit 7 and the reception-side reference signal.

[0028] The set delay time acquisition unit 57 acquires a preset set delay time Tds based on the delay time calculated by the delay time calculation unit 56. In the embodiment of the present disclosure, as shown in FIG. 4, the set delay time Tds is set to a constant value larger than the assumed maximum value Tdm of the delay time Td calculated by the delay time calculation unit 56. For example, taking the internal delay in the transmission unit 2 as Td1, the transmission delay when transmitting video data from the transmission unit 2 to the reception unit 5 as Td2, and the internal delay in the reception unit 5 as Td3, the maximum value Tdm of the sum of the internal delay Td1, the transmission delay Td2, and the internal delay Td3 is grasped in advance through prior analysis, actual measurement, etc. Then, the set delay time Tds is set to be larger than the maximum value Tdm. Here, for example, the set delay time Tds is set to 300 ms.

[0029] The video data output unit 58 delays and outputs the video data stored in the video data buffer unit 52 based on the set delay time Tds acquired by the set delay time acquisition unit 57. That is, for example, when the video captured by the imaging device 3 is 30 frames per second, the video captured by the imaging device 3, transmitted frame by frame to the reception unit 5 in sequence, and stored in the video data buffer unit 52 is delayed by the length of the set delay time Tds and then displayed on the video display device 8.

[0030] Note that the calculation of the delay time in the delay time calculation unit 56 and the acquisition of the set delay time Tds in the set delay time acquisition unit 57 as described above are performed only when the data reception unit 51 receives the video data. As described above, when other communications are being performed via the wireless communication network N, the data transmission unit 25 does not transmit the video data. Therefore, in the blinking detection unit 7, since a blinking signal indicating the blinking state of the marker light detected based on the video data cannot be obtained, the delay time calculation unit 56 cannot calculate the delay time based on the blinking signal and the reception side reference signal either. Therefore, in the embodiment of the present disclosure, for this reason, the delay time calculation unit 56 performs the calculation of the delay time in the delay time calculation unit 56 and the acquisition of the set delay time Tds in the set delay time acquisition unit 57 only when the video data is received.

[0031] On the other hand, when other communications are being performed via the wireless communication network N and the video data from the data transmission unit 25 is not transmitted, the reception unit 5 maintains the set delay time Tds set by the set delay time acquisition unit 57 at that time and delays and outputs the video data by the video data output unit 58.

[0032] (Configuration of the master unit) As shown in FIG. 5, the master unit 9 generates a beacon signal for synchronizing among a plurality of slave units. Here, examples of the plurality of slave units include the above-described transmission unit 2 and the reception unit 5. Also, a plurality of transmission units 2 and a plurality of reception units 5 may be used as the plurality of slave units. Further, for example, the transmission unit 2 may be used as the master unit 9 and the reception unit 5 may be used as a slave unit.

[0033] The master unit 9 includes a clock signal generation unit 91, a pulse signal generation unit 92, a beacon signal generation unit 93, and a beacon signal output unit 94. The clock signal generation unit 91 generates a reference clock signal. The clock signal generation unit 91 is, for example, a crystal oscillator and generates a highly accurate reference clock signal having a predetermined frequency. As the frequency of the reference clock signal, for example, 12.8 MHz can be exemplified. The pulse signal generation unit 92 is a frequency division circuit and generates a pulse signal having a predetermined period based on the reference clock signal generated by the clock signal generation unit 91. In the embodiment of the present disclosure, the pulse signal generation unit 92 generates, for example, a pulse signal having a frequency of 1 kHz. The beacon signal generation unit 93 generates a beacon signal for blinking the blinking marker 4 based on the pulse signal generated by the pulse signal generation unit 92. The beacon signal output unit 94 outputs the generated beacon signal to a plurality of external slave units (transmission unit 2, reception unit 5) via the wireless communication network N. In the transmission-side synchronization signal reception unit 23 of the transmission unit 2 and the reception-side synchronization signal reception unit 53 of the reception unit 5 shown in FIG. 3, the beacon signal output from the beacon signal output unit 94 is received as a reference synchronization signal.

[0034] (Procedure of video display method) As shown in FIG. 6, the video display method according to the embodiment of the present disclosure includes a step S11 of blinking marker light, a step S12 of shooting a video, a step S13 of transmitting video data, a step S21 of receiving the video data, a step S22 of temporarily storing the video data, a step S23 of displaying the video, a step S24 of detecting the blinking of the marker light, a step S25 of transmitting a reception-side reference signal, a step S26 of calculating a delay time, a step S27 of obtaining a set delay time, and a step S28 of delaying and outputting the video data.

[0035] In step S11 of blinking the marker light, the marker light is blinked by the blinking marker 4 at a preset time interval under the control of the blinking control unit 22. In step S12 of shooting a video, the shooting device 3 shoots a video including the vehicle compartment 105 as the shooting object T and the blinking of the marker light of the blinking marker 4 at the shooting location. In step S13 of transmitting the video data, the data transmission unit 25 transmits the video data shot by the shooting device 3. Thereby, the video data shot by the shooting device 3 is transmitted to the receiving unit 5 via the wireless communication network N. Here, when other communications such as the communication between the other transmission unit 2 and the receiving unit 5 are being performed via the wireless communication network N, the data transmission unit 25 does not transmit the video data. When other communications are being performed via the wireless communication network N, the data transmission unit 25 re-checks the communication state of the wireless communication network N after a preset predetermined waiting time has elapsed, and after confirming that no other communications are being performed, transmits the video data.

[0036] In step S21 of receiving the video data, the data receiving unit 51 receives the video data transmitted from the data transmission unit 25 via the wireless communication network N. In step S22 of temporarily storing the video data, the video data buffer unit 52 temporarily stores the video data received by the data receiving unit 51.

[0037] In step S23 of displaying an image, an image based on the data received by the data reception unit 51 is displayed on the display device 6. The image displayed on the display device 6 includes at least an image of the marker light of the blinking marker 4 captured by the imaging device 3.

[0038] In step S24 of detecting the blinking of the marker light, the blinking detection unit 7 detects the blinking of the marker light in the image displayed on the display device 6. The blinking detection unit 7 detects the blinking state (lighting or extinguishing) of the marker light. The blinking detection unit 7 outputs a blinking signal indicating the blinking state of the marker light to the delay time calculation unit 56.

[0039] In step S25 of transmitting the reception-side reference signal, the reception-side reference signal transmission unit 55 transmits a reception-side reference signal synchronized with the reference synchronization signal. The reception-side reference signal transmission unit 55 outputs the transmitted reception-side reference signal to the delay time calculation unit 56.

[0040] In step S26 of calculating the delay time, the delay time calculation unit 56 calculates the delay time from when the image is captured by the imaging device 3 until it is displayed on the display device 6 based on the blinking signal indicating the blinking state of the marker light detected by the blinking detection unit 7 and the reception-side reference signal.

[0041] In step S27 of obtaining the set delay time, a preset set delay time Tds is obtained based on the delay time calculated by the delay time calculation unit 56. In an embodiment of the present disclosure, the set delay time Tds is a constant value larger than a preset maximum value Tdm of the delay time Td calculated by the delay time calculation unit 56.

[0042] In step S28 of delaying and outputting the image data, the image data stored in the image data buffer unit 52 is delayed and output based on the set delay time Tds obtained by the set delay time acquisition unit 57. As a result, an image delayed by a fixed set delay time Tds is continuously displayed on the image display device 8.

[0043] In addition, when other communications are performed via the wireless communication network N and the video data from the data transmission unit 25 is not transmitted, in step S21 of receiving video data, the data receiving unit 51 may not receive the video data transmitted from the data transmission unit 25 via the wireless communication network N. In this case, the receiving unit 5 does not execute the processes after step S21. That is, in the frequency division circuit 542, since the reference synchronization signal received by the reception-side synchronization signal receiving unit 53 is not input, the pulse signal is not reset, and the reception-side reference signal transmission unit 55 does not transmit the reception-side reference signal. As a result, at that time, the set delay time Tds set by the set delay time acquisition unit 57 is maintained. In this way, by using the set delay time Tds that has already been set at that time in the receiving unit 5, even when other communications are being performed in the wireless communication network N, the influence can be suppressed, and the video can be displayed with a delay based on the set delay time Tds. As a result, even when other communications are being performed in the wireless communication network N, the delayed video can be stably displayed.

[0044] (Function and effect) According to the video display system 1 and the video display method having the above configuration, the video of the imaging target T is captured, and the data of the video is transmitted to the receiving unit 5. The receiving unit 5 displays the video based on the received video data on the display device 6. Further, the receiving unit 5 temporarily stores the received video data in the video data buffer unit 52. In the transmission unit 2, based on the reference synchronization signal, the blinking marker 4 periodically blinks the marker light. In the imaging device 3, an image including the blinking marker 4 is captured together with the imaging target T. On the display device 6 of the receiving unit 5, an image in which the marker light of the blinking marker 4 blinks together with the imaging target T is displayed. The blinking detection unit 7 detects the blinking of the marker light in the image displayed on the display device 6. In the receiving unit 5 grounded at a separated location, the receiving-side reference signal transmission unit 55 transmits a receiving-side reference signal synchronized with the reference synchronization signal. The delay time calculation unit 56 calculates the delay time from when the image is captured by the imaging device 3 until it is displayed on the display device 6 based on the blinking signal indicating the blinking state of the marker light detected by the blinking detection unit 7 and the receiving-side reference signal. Here, the receiving-side reference signal is synchronized with the reference synchronization signal on the transmission side. That is, the time difference between the blinking signal indicating the blinking state of the marker light detected by the blinking detection unit 7 and the receiving-side reference signal is the delay time. The set delay time acquisition unit 57 acquires a preset set delay time Tds based on the calculated delay time. The video data output unit 58 delays and outputs the video data stored in the video data buffer unit 52 based on the acquired set delay time Tds. In this way, by delaying and outputting the video data received and temporarily stored by the receiving unit 5 based on the preset set delay time Tds, even when the actual delay time fluctuates, regardless of the actual delay time, the video can be delayed and displayed based on the preset fixed set delay time Tds. As a result, the variation in the delay of the video can be suppressed.

[0045] Also, by setting the set delay time Tds to a fixed value larger than the assumed maximum value Tdm of the delay time calculated by the delay time calculation unit 56, regardless of the actual delay time, the video can be stably displayed at a fixed set delay time Tds.

[0046] Also, in the transmission unit 2 and the reception unit 5, a beacon signal is received from an external master unit 9 as a reference synchronization signal. Based on the received beacon signal as the reference synchronization signal, the transmission unit 2 and the reception unit 5 can be synchronized, and the blinking of the marker light, the calculation of the delay time, etc. can be performed.

[0047] Also, in the master unit 9, by generating a beacon signal for blinking the blinking marker 4 with a pulse signal generated based on the reference clock signal, other transmission units 2 and reception units 5 that have received this beacon signal can use the beacon signal as a reference synchronization signal to achieve synchronization.

[0048] (First Modification Example of the Embodiment) In the above embodiment, the set delay time Tds is set to a constant value larger than the maximum value Tdm that is assumed in advance for the delay time calculated by the delay time calculation unit 56, but it is not limited to this. For example, as shown in FIG. 7, the set delay time Tds2 may be set to a constant value smaller than the maximum value Tdm that is assumed in advance for the delay time Td calculated by the delay time calculation unit 56. In this case, the video data output unit 58 stops outputting the video of the frame whose delay time is larger than the set delay time Tds2, and outputs only the video of the frame whose delay time is equal to or less than the set delay time Tds2. Thereby, the delay time (set delay time Tds2) of the video displayed on the video display device 8 can be reduced. Also, when the delay time becomes excessive due to some factor, the video can be stably displayed without displaying the video of the frame with the excessive delay time.

[0049] (Second Modification Example of the Embodiment) Also, for example, as shown in FIG. 8, as the set delay time, a first set delay time Tds3 and a second set delay time Tds4 whose delay time is larger than the first set delay time Tds3 may be used. Here, for example, the first set delay time Tds3 can be set to 300 ms and the second set delay time Tds4 can be set to 450 ms. In this case, the setting delay time acquisition unit 57 acquires either the preset first setting delay time Tds3 or the second setting delay time Tds4 whose delay time Td is greater than the first setting delay time Tds3, based on the delay time Td calculated by the delay time calculation unit 56. For example, when the delay time Td is shorter than the first setting delay time Tds3, the video may be displayed at the first setting delay time Tds3, and when the delay time Td is greater than the first setting delay time Tds3, the video may be displayed at the second setting delay time Tds4. Thereby, the video can be stably displayed. In addition, in the above modification, for example, when the average of the actual delay time Td over a certain period (for example, 10 seconds) exceeds a predetermined ratio (for example, 2 / 3) of the first setting delay time Tds3, the setting delay time may be switched from the first setting delay time T3 to the second setting delay time T4. Also, for example, when the average of the actual delay time Td over a certain period (for example, 10 seconds) is less than a predetermined ratio (for example, 2 / 3) of the second setting delay time Tds4, the setting delay time may be switched from the second setting delay time Tds4 to the first setting delay time T3.

[0050] (Third Modification of the Embodiment) Also, for example, when the transmission unit 2 and the reception unit 5 are capable of communicating via a plurality of wireless communication networks N, one of the first set delay time Tds5 and the second set delay time Tds6 may be selected based on the wireless communication network N used for communication. Here, examples of the plurality of wireless communication networks N include, for example, a wireless LAN with a small delay time and a wireless telephone communication network such as LTE with a larger delay time than the wireless LAN. Specifically, for example, within the ship 100, due to various factors, the radio wave reflection and shielding conditions fluctuate, and the communication state between the transmission unit 2 and the reception unit 5 may become unstable. For this reason, there may be a case where a wireless LAN and a wireless telephone communication network are provided as the plurality of wireless communication networks N. In this case, for example, when communicating using the wireless communication network N1 with a large delay time Td, the video may be displayed with the second set delay time Tds6, and when communicating using the wireless communication network N2 with a small delay time Td, the video may be displayed with the first set delay time Tds5.

[0051] For example, when switching the wireless communication network N used for transferring video data from the wireless communication network N1 with a large delay time to the wireless communication network N2 with a small delay time, as shown in FIG. 10, in the state of using the wireless communication network N1 with a large delay time, each frame F1 of the video is displayed with the second set delay time Tds6 (for example, 3 seconds). After switching the wireless communication network N used for transferring video data from the wireless communication network N1 with a large delay time to the wireless communication network N2 with a small delay time, the display time T2 of the video of each frame F2 is shortened over a plurality of frames F2 of the video. Thereafter, each frame F3 of the video is displayed with the first set delay time Tds5 (for example, 300 ms).

[0052] Also, for example, as shown in FIG. 11, when switching the wireless communication network N used for transferring video data from the wireless communication network N2 with a small delay time to the wireless communication network N1 with a large delay time, in the state where the wireless communication network N2 with a small delay time is used, each frame F4 of the video is displayed with the first set delay time Tds5. Then, over a plurality of frames F5, the display time T5 of each frame F5 is increased. Then, the wireless communication network N used for transferring video data is switched from the wireless communication network N2 with a small delay time to the wireless communication network N1 with a large delay time, and each frame F6 of the video is displayed with the second set delay time Tds6.

[0053] In this way, when communicating using the wireless communication network N1 with a large delay time, the video can be displayed with the second set delay time Tds6, and when communicating using the wireless communication network N2 with a small delay time, the video can be displayed with the first set delay time Tds5. Thereby, the set delay time Tds can be adjusted according to the communication situation etc. via the wireless communication network N.

[0054] In the above embodiment, the video display system 1 is installed in the vehicle mounting space 102s on the vehicle deck 102 provided inside the hull of the ship 100, but it is not limited to this. The video display system 1 may be provided outside the hull of the ship 100, or may be provided at a location other than the ship 100.

[0055] Also, in the above embodiment, the transmission unit 2 equipped with the imaging device 3 is fixed to the hull, and the reception unit 5 is mounted on the vehicle, but it is not limited to this. For example, the transmission unit 2 may be mounted on various moving bodies including vehicles, ships, etc., and the reception unit 5 may be provided at a position separated from the moving body. Thereby, the moving situation of the moving body can be confirmed by video at a position separated from the moving body. For example, the transmission unit 2 may be provided on an operation target that is remotely operated by a remote operation device (not shown). Examples of the operation target include various moving bodies such as ships and vehicles. In the case of these moving bodies, the transmission unit 2 is mounted on the moving body, and the imaging device 3 of the transmission unit 2 captures the front in the traveling direction of the moving body as the imaging target T. Further, examples of the operation target include various devices and apparatuses. In this case, the imaging device 3 of the transmission unit 2 captures, as the imaging target T, for example, a part to be remotely operated in the devices and apparatuses. The transmission unit 2 may be attached to the devices and apparatuses, or may be provided on the floor, wall, ceiling, etc. around the devices and apparatuses.

[0056] <Supplementary Note> The video display system 1 and the video display method described in the embodiment are understood as follows, for example.

[0057] (1) The video display system 1 according to the first aspect includes a transmission unit 2 disposed at the shooting location, and a reception unit 5 installed at a separated location away from the shooting location. The transmission unit 2 includes a blinking marker 4 that periodically blinks marker light based on a reference synchronization signal at the shooting location, a shooting device 3 that shoots a video including a shooting target T and the blinking marker 4 at the shooting location, and a data transmission unit 25 that transmits the data of the video shot by the shooting device 3 via a wireless communication network N. The reception unit 5 includes a data reception unit 51 that receives the data of the video via the wireless communication network N, a video data buffer unit 52 that temporarily stores the data of the video received by the data reception unit 51, a display device 6 that displays a video based on the received data of the video, a blinking detection unit 7 that detects the blinking of the marker light in the video displayed on the display device 6, a reception-side reference signal transmission unit 55 that transmits a reception-side reference signal synchronized with the reference synchronization signal at the separated location, a delay time calculation unit 56 that calculates a delay time from when the video was shot by the shooting device 3 until it is displayed on the display device 6 based on a blinking signal indicating the blinking state of the marker light detected by the blinking detection unit 7 and the reception-side reference signal, a set delay time acquisition unit 57 that acquires a preset set delay time Tds based on the delay time calculated by the delay time calculation unit 56, and a video data output unit 58 that delays and outputs the data of the video stored in the video data buffer unit 52 based on the set delay time Tds acquired by the set delay time acquisition unit 57.

[0058] In this video display system 1, the shooting device 33 of the transmission unit 2 disposed at the shooting location shoots a video of the shooting target T, and the data of the video is transmitted by the data transmission unit 25 to the reception unit 5. In the reception unit 5, a video based on the received video data is displayed on the display device 6. Also, in the reception unit 5, the received video data is temporarily stored in the video data buffer unit 52. In the transmission unit 2, based on the reference synchronization signal, the blinking marker 4 periodically blinks the marker light. In the imaging device 3, an image including the blinking marker 4 is captured together with the imaging target T. On the display device 6 of the receiving unit 5, an image in which the marker light of the blinking marker 4 blinks together with the imaging target T is displayed. The blinking detection unit 7 detects the blinking of the marker light in the image displayed on the display device 6. In the receiving unit 5 grounded at a separated location, the receiving-side reference signal transmitting unit 55 transmits a receiving-side reference signal synchronized with the reference synchronization signal. The delay time calculation unit 56 calculates the delay time from when the image is captured by the imaging device 3 until it is displayed on the display device 6 based on the blinking signal indicating the blinking state of the marker light detected by the blinking detection unit 7 and the receiving-side reference signal. Here, the receiving-side reference signal is synchronized with the reference synchronization signal on the transmission side. That is, the time difference between the blinking signal indicating the blinking state of the marker light detected by the blinking detection unit 7 and the receiving-side reference signal is the delay time. The set delay time acquisition unit 57 acquires a preset set delay time Tds based on the calculated delay time. The video data output unit 58 delays and outputs the video data stored in the video data buffer unit 52 based on the acquired set delay time Tds. In this way, by delaying and outputting the video data received and temporarily stored by the receiving unit 5 based on the preset set delay time Tds, even when the actual delay time fluctuates, regardless of the actual delay time, the video can be delayed and displayed based on the preset set delay time Tds. As a result, the variation in video delay can be suppressed.

[0059] (2) The video display system 1 according to the second aspect is the video display system 1 in (1), wherein the set delay time Tds is set to a constant value larger than a preset maximum value of the delay time calculated by the delay time calculation unit 56.

[0060] By setting the set delay time Tds to a constant value greater than the maximum value of the delay time expected in advance by the delay time calculation unit 56, the video can be displayed with a stable set delay time Tds regardless of the delay time.

[0061] (3) The video display system 1 according to the third aspect is the video display system 1 of (1), wherein the video data output unit 58 stops outputting a video having a delay time greater than the set delay time Tds.

[0062] By stopping the output of a video having a delay time greater than the set delay time Tds, the video can be stably displayed even when the delay time becomes excessive due to some factor.

[0063] (4) The video display system 1 according to the fourth aspect is the video display system 1 of (1), wherein the set delay time acquisition unit 57 acquires either a preset first set delay time Tds3 or a second set delay time Tds4 having a delay time greater than the first set delay time Tds3, based on the delay time calculated by the delay time calculation unit 56.

[0064] As a result, the first set delay time Tds3 and the second set delay time Tds4 can be selected. Therefore, when the delay time is shorter than the first set delay time Tds3, the video is displayed with the first set delay time Tds3, and when the delay time is greater than the first set delay time Tds3, the video is displayed with the second set delay time Tds4, so that the video can be stably displayed.

[0065] (5) The video display system 1 according to the fifth aspect is the video display system 1 of (1), wherein the transmission unit 2 and the reception unit 5 are communicable via a plurality of wireless communication networks N, and the setting delay time acquisition unit 57 is based on the wireless communication network N used for communication between the transmission unit 2 and the reception unit 5 among the plurality of wireless communication networks N, and acquires either a preset first setting delay time Tds5 or a second setting delay time Tds6 having a larger delay time than the first setting delay time Tds5.

[0066] Accordingly, when communicating via a plurality of wireless communication networks N, either the first setting delay time Tds5 or the second setting delay time Tds6 is selected based on the wireless communication network N used for communication. Thereby, for example, when communicating using a wireless communication network N with a large delay time, the video is displayed with the second setting delay time Tds6, and when communicating using a wireless communication network N with a small delay time, the video can be displayed with the first setting delay time Tds5. Thereby, the setting delay time Tds can be adjusted according to the communication situation via the wireless communication network N.

[0067] (6) The video display system 1 according to the sixth aspect is the video display system 1 of any one of (1) to (5), wherein the data transmission unit 25 transmits the data of the video captured by the imaging device 3 via the wireless communication network N when no other communication is being performed via the wireless communication network N, and the reception unit 5 calculates the delay time by the delay time calculation unit 56 when the data reception unit 51 receives the data of the video, and when the data reception unit 51 is not receiving the data of the video, the video data output unit 58 outputs the data of the video after delaying it based on the setting delay time Tds set at that time.

[0068] As a result, when no other communication is being performed via the wireless communication network N, the data transmission unit 25 transmits video data. That is, when other communication is being performed via the wireless communication network N, the data transmission unit 25 does not transmit video data. This suppresses the interleaving and interference of multiple communications on the wireless communication network N. On the other hand, when other communication is being performed via the wireless communication network N, since the data transmission unit 25 does not transmit video data, the receiving unit 5 does not receive video data. In this case, the receiving unit 5 outputs the video data after delaying it based on the set delay time Tds set at that time by the video data output unit 58. As a result, even when other communication is being performed on the wireless communication network N, its impact can be suppressed, and the video can be displayed after being delayed based on the set delay time Tds. As a result, the delayed video can be stably displayed.

[0069] (7) The video display method according to the seventh aspect includes: a step S11 of periodically blinking marker light based on a reference synchronization signal at a shooting location; a step S12 of shooting a video including a shooting target T and the blinking marker 4 at the shooting location; a step S13 of transmitting the data of the shot video via a wireless communication network N; a step S21 of receiving the data of the video via the wireless communication network N; a step S22 of temporarily storing the received data of the video; a step S23 of displaying a video based on the received data of the video at a separation location away from the shooting location; a step S24 of detecting the blinking of the marker light in the displayed video; a step S25 of transmitting a reception-side reference signal synchronized with the reference synchronization signal at a separation location away from the shooting location; a step S26 of calculating a delay time from when the video was shot at the shooting location to when it is displayed at the separation location based on the detected blinking signal indicating the blinking state of the marker light and the reception-side reference signal; a step S27 of obtaining a preset set delay time Tds based on the calculated delay time; and a step S28 of delaying and outputting the temporarily stored data of the video based on the set delay time Tds.

[0070] In this video display method, after receiving and temporarily storing the data of the video, by delaying and outputting it based on a preset set delay time Tds, even when the actual delay time fluctuates, regardless of the actual delay time, the video can be delayed and displayed based on the preset set delay time Tds. As a result, the variation in the delay of the video can be suppressed.

Explanation of Signs

[0071] 1... Video display system 2... Transmission unit 3... Shooting device 4... Blinking marker 5... Reception unit 6... Display device 7... Blinking detection unit 8... Video display device 9…Master unit 20…Transmitter controller 22…Flashing control unit 23…Transmitter side synchronization signal receiver (beacon signal receiver) 25…Data transmitter 33…Imaging device 50…Receiver controller 51…Data receiver 52…Video data buffer unit 53…Receiver side synchronization signal receiver (beacon signal receiver) 54…Flashing control unit 55…Receiver side reference signal transmitter 56…Delay time calculation unit 57…Set delay time acquisition unit 58…Video data output unit 59…Flashing marker 91…Clock signal generation unit 92…Pulse signal generation unit 93…Beacon signal generation unit 94…Beacon signal output unit 100…Ship 102…Vehicle deck 102s…Vehicle loading space 105…Vehicle compartment 106…Ceiling 221…Crystal oscillator 222…Frequency divider circuit 223…Integrating counter unit 541…Crystal oscillator 542…Frequency divider circuit 543…Integrating counter unit C…Vehicle F1~F6…Frame N…Wireless communication network N1…Wireless communication network N2…Wireless communication network T…Imaging target Td…Delay time Tdm…Maximum value Tds…Set delay time Tds2…Set delay time Tds3…First set delay time Tds4…Second set delay time Tds5…First set delay time Tds6…Second set delay time

Claims

1. A video display system comprising a transmission unit disposed at a shooting location and a reception unit installed at a separation location away from the shooting location, wherein the transmission unit includes: a flashing marker that periodically flashes marker light based on a reference synchronization signal at the shooting location; a shooting device that shoots a video including a shooting target and the flashing marker at the shooting location; a data transmission unit that transmits data of the video shot by the shooting device via a wireless communication network; and the reception unit includes: a data reception unit that receives the data of the video via the wireless communication network; a video data buffer unit that temporarily stores the data of the video received by the data reception unit; a display device that displays a video based on the received data of the video; a flashing detection unit that detects the flashing of the marker light in the video displayed on the display device; a reception-side reference signal transmission unit that transmits a reception-side reference signal synchronized with the reference synchronization signal at the separation location; a delay time calculation unit that calculates a delay time from when the video is shot by the shooting device until it is displayed on the display device based on a flashing signal indicating the flashing state of the marker light detected by the flashing detection unit and the reception-side reference signal; a set delay time acquisition unit that acquires a preset set delay time based on the delay time calculated by the delay time calculation unit; and a video data output unit that delays and outputs the data of the video stored in the video data buffer unit based on the set delay time acquired by the set delay time acquisition unit. Video display system.

2. The set delay time is set to be greater than a preset maximum value of the delay time calculated by the delay time calculation unit. The video display system according to claim 1.

3. The video data output unit stops outputting a video with a delay time greater than the set delay time. The video display system according to claim 1.

4. The set delay time acquisition unit acquires either a preset first set delay time or a second set delay time with a delay time greater than the first set delay time based on the delay time calculated by the delay time calculation unit. The video display system according to claim 1.

5. The transmission unit and the reception unit are capable of communicating via a plurality of wireless communication networks. Based on the wireless communication network used for communication between the transmission unit and the reception unit among the plurality of wireless communication networks, the setting delay time acquisition unit acquires either a preset first setting delay time or a second setting delay time whose delay time is greater than the first setting delay time. The video display system according to claim 1.

6. When no other communication is being performed via the wireless communication network, the data transmission unit transmits the data of the video captured by the imaging device via the wireless communication network. The reception unit When the data reception unit receives the data of the video, the delay time calculation unit calculates the delay time. When the data reception unit is not receiving the data of the video, the video data output unit delays and outputs the data of the video based on the setting delay time set at that time. The video display system according to claim 1.

7. The step of periodically flashing marker light with a flashing marker based on a reference synchronization signal at the shooting location; The step of shooting a video including the shooting target and the flashing marker at the shooting location; The step of transmitting the data of the captured video via a wireless communication network; The step of receiving the data of the video via the wireless communication network; The step of temporarily storing the received video data; The step of displaying a video based on the received video data at a separation location away from the shooting location; The step of detecting the flashing of the marker light in the displayed video; The step of transmitting a reception-side reference signal synchronized with the reference synchronization signal at a separation location away from the shooting location; Based on the flashing signal indicating the detected flashing state of the marker light and the reception-side reference signal, calculating the delay time from when the video was captured at the shooting location until it is displayed at the separation location; The step of acquiring a preset setting delay time based on the calculated delay time; Including the step of delaying and outputting the temporarily stored video data based on the setting delay time. Video display method.

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