Video transmission device, video transmission method, and video transmission program

Abstract

To provide a video transmission device capable of wirelessly transmitting video data while taking into account the influence of relay communication between wireless devices.SOLUTION: A video transmission device (wireless repeater) includes a wireless communication unit, a video acquisition unit, and a control unit. The wireless communication unit performs wireless communication with a wireless router or a wireless repeater. The video acquisition unit acquires video data captured and generated by a camera. The control unit performs a reduction process to reduce the bandwidth used by the wireless communication unit by changing the bit rate of the video data or the number of transmittable units on the basis of the wireless communication settings of the wireless network, and transmits the video data via the wireless communication unit.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention mainly relates to a moving image transmitting device that transmits moving images using a wireless network. [Background technology]

[0002] The video wireless transmission device in Patent Document 1 wirelessly transmits digitized data of surveillance camera video. The video wireless transmission device optimizes video quality by allocating wireless communication channels based on quality information such as packet error rate, number of retransmissions, and received power. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-329707 A Summary of the Invention [Problem to be solved by the invention]

[0004] The wireless network described in Patent Document 1 does not take into consideration relay communication, which is communication between wireless devices, and therefore does not take into consideration the reduction in available bandwidth that accompanies relay communication.

[0005] The present invention has been made in view of the above circumstances, and a main object of the present invention is to provide a video transmission device that can perform wireless communication of video data while taking into consideration the influence of relay communication between wireless devices.

[0006] The problem to be solved by the present invention has been described above. Next, the means for solving this problem and the effects thereof will be described.

[0007] According to a first aspect of the present invention, there is provided a video transmission device having the following configuration. That is, in a wireless network configured with wireless devices including a wireless router and multiple wireless repeaters, the video transmission device corresponds to one of the wireless repeaters. The video transmission device includes a wireless communication unit, a video acquisition unit, and a control unit. The wireless communication unit performs wireless communication with the wireless router or the other wireless repeaters. The video acquisition unit acquires video data captured and generated by a camera. The control unit performs a reduction process to reduce the bandwidth used by the wireless communication unit by changing the bit rate or the number of transmittable units of the video data based on the wireless communication settings of the wireless network, and causes the video data to be transmitted via the wireless communication unit.

[0008] This makes it possible to reduce the bandwidth used by the wireless communication unit based on the wireless communication settings of a wireless network using multiple wireless repeaters (i.e., taking into account the influence of relayed communication between wireless devices), and as a result, the bandwidth used by the video transmission device can be kept within an appropriate range.

[0009] The video transmission device is preferably configured as follows. That is, the video transmission device includes a storage unit. The storage unit stores the wireless communication settings and the video transmission settings together with the video data acquired by the video acquisition unit. When the control unit changes the bit rate, the control unit converts the video data stored in the storage unit based on the video transmission settings, and transmits the converted video data via the wireless communication unit.

[0010] This makes it possible to reduce bandwidth usage by storing high-quality pre-conversion video data in the storage unit while transmitting the converted video data.

[0011] In the moving image transmission device, it is preferable that the control unit changes the bit rate by changing at least one of a frame rate, a resolution, a moving image format, and a key frame frequency.

[0012] This allows the bitrate to be varied in a variety of ways.

[0013] In the above-mentioned video transmission device, it is preferable that the wireless communication settings used by the control unit to change the bit rate or the number of transmittable devices include at least the maximum number of simultaneous connections and the maximum number of hops between the wireless devices that make up the wireless network.

[0014] This makes it possible to change to an appropriate bit rate or number of transmittable devices based on information that is specific to wireless relay communication and that affects the amount of bandwidth used.

[0015] In the above-mentioned video transmission device, it is preferable that the wireless communication settings used by the control unit to change the bit rate or the number of transmittable units include at least one of the wireless communication standard and bandwidth used in the wireless network.

[0016] This makes it possible to change to an appropriate bit rate or number of transmittable devices based on information that affects the size of the bandwidth available for wireless relay communication.

[0017] In the moving image transmission device, it is preferable that it is possible to switch whether or not the reduction process is performed.

[0018] When important video data is being handled, the reduction process is not executed, thereby making it possible to transmit high quality video data.

[0019] The video transmission device is preferably configured as follows: That is, at least one of the wireless repeaters is capable of switching whether or not to execute the reduction process. If there are other wireless repeaters in the wireless network that do not execute the reduction process, the control unit changes the bit rate of the video data or the number of transmittable units based on the number of other wireless repeaters in the wireless network that do not execute the reduction process and the number of wireless repeaters in the wireless network (including the control unit itself) that execute the reduction process.

[0020] This makes it possible to suppress the shortage of bandwidth while allowing other wireless repeaters that do not perform the reduction process to transmit high-quality video data.

[0021] According to a second aspect of the present invention, there is provided a video transmission method as follows. The video transmission method includes a video acquisition step, a reduction processing step, and a transmission step. In the video acquisition step, video data captured and generated by a camera is acquired. In the reduction processing step, a reduction process is performed to reduce the bandwidth used by the wireless repeater by changing the bit rate of the video data or the number of transmittable units based on a wireless communication setting of the wireless network. In the transmission step, the video data is wirelessly transmitted using the wireless repeater.

[0022] According to a third aspect of the present invention, there is provided a video transmission program having the following configuration. The video transmission program causes a wireless repeater to execute a video acquisition step, a reduction processing step, and a transmission step. In the video acquisition step, video data captured and generated by a camera is acquired. In the reduction processing step, a reduction process is performed to reduce the bandwidth used by the wireless repeater by changing the bit rate of the video data or the number of transmittable units based on wireless communication settings of the wireless network. In the transmission step, the video data is wirelessly transmitted using the wireless repeater. [Brief description of the drawings]

[0023] [Figure 1] 1 is a schematic diagram of a wireless communication system according to an embodiment of the present invention. [Diagram 2] Block diagram of a wireless repeater. [Diagram 3] FIG. 2 is a diagram illustrating wireless communication via a wireless repeater and the number of hops. [Figure 4] 1 is a table showing wireless communication settings and video transmission settings. [Diagram 5] 10 is a flowchart showing a process of changing a video transmission setting based on a wireless communication setting. [Figure 6]6 is a flowchart showing a process performed by a wireless repeater regarding video data. [Figure 7] 11 is a flowchart showing a process of adjusting a band for each wireless repeater. [Figure 8] 11 is a table showing the bandwidth for each wireless repeater before and after the bandwidth is adjusted. [Figure 9] 10 is a flowchart showing a process of changing wireless communication settings based on video transmission settings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Next, an embodiment of the present invention will be described with reference to the drawings. First, a wireless communication system 1 will be described with reference to Figs.

[0025] The wireless communication system 1 is installed in a facility such as a factory, a parking lot, or an office. The wireless communication system 1 is a system for transmitting video data captured and generated by multiple cameras 31 via wireless communication so that the video data can be viewed on a notebook PC 32 or the like. The wireless communication system 1 includes a wireless router 10 and multiple wireless repeaters 20. Hereinafter, the wireless router 10 and the wireless repeaters 20 are collectively referred to as wireless devices.

[0026] The wireless router 10 establishes a wireless LAN environment in the facility that complies with a predetermined wireless communication standard. The wireless communication standard may be, for example, IEEE802.11, but is not limited to this. In the following description, the wireless LAN environment established by the wireless router 10 and the network used for wireless communication between the wireless router 10 and the wireless repeater 20 will be referred to as a wireless network.

[0027] The wireless repeater 20 is a device that relays communication in a wireless network and transmits video data captured by a camera 31, and is also called a video transmitting device. As shown in FIG. 2, the wireless repeater 20 includes a wireless communication unit 21, a video acquisition unit 22, a control unit 23, and a storage unit 24.

[0028] The wireless communication unit 21 includes a wireless communication module, and communicates wirelessly with the wireless router 10, other wireless repeaters 20, and the notebook PC 32, etc. The video acquisition unit 22 includes a wired communication module, and acquires video data from one or more cameras 31. The control unit 23 is realized by a calculation device such as a CPU operating according to a program stored in the storage unit 24, and performs processing related to wireless communication and processing related to video data. The storage unit 24 is an HDD, SSD, or flash memory, and stores programs, control data, video data, etc.

[0029] In the above, the notebook PC 32 is given as an example of a device that receives video data and the like via a wireless network, but instead of or in addition to the notebook PC 32, a smartphone or a tablet terminal may be used.

[0030] With reference to Fig. 3, relay communication using the wireless repeater 20 will be described. The wireless repeater 20 communicates between wireless devices using a WDS (Wireless Distribution System). Specifically, the wireless communication unit 21 of the wireless repeater 20 performs wireless communication with the wireless router 10 or another wireless repeater 20. This realizes wireless relay communication and realizes a wide-area wireless LAN environment.

[0031] The dashed lines shown in Figures 1 and 3 are lines connecting wireless devices that can directly communicate with each other via wireless communication. Figure 3 shows a route for transferring video data received by the wireless router 10 to the notebook PC 32. In the example shown in Figure 3, the video data is transmitted to the notebook PC 32 via three wireless repeaters 20. The number of hops in this case is three.

[0032] Next, problems that arise in relay communication between wireless devices and means for solving these problems will be described.

[0033] The maximum bandwidth available in a wireless network is called the maximum bandwidth used. The maximum bandwidth used depends on the wireless communication standard, the bandwidth, and the like. In addition, when relay communication is performed between wireless devices, the bandwidth is also used by the relay communication. Therefore, as the number of wireless devices communicating in the wireless network increases, and as the number of hops increases, a larger bandwidth is used. Therefore, in this embodiment, the bandwidth required for transmitting video data may be insufficient.

[0034] In order to solve this problem, in this embodiment, a reduction process is performed to change the video transmission settings based on the wireless communication settings and reduce the bandwidth used by the wireless repeater 20. The wireless communication settings are settings related to a wireless network including relay communication. As shown in FIG. 4, the wireless communication settings include the maximum number of simultaneous connections, the maximum number of hops, a wireless communication standard, and a bandwidth. The wireless communication settings shown in FIG. 4 are an example, and at least one item may be deleted, or another item that affects the bandwidth may be added.

[0035] The maximum number of simultaneous connections is the number of wireless devices that connect to a wireless network and communicate. In the wireless communication system 1, a wireless network exceeding the maximum number of simultaneous connections is not constructed. The greater the maximum number of simultaneous connections, the smaller the bandwidth that can be used per device. The maximum number of hops is the maximum value of the number of hops described above. If the number of hops exceeds the maximum number of hops, the corresponding packet is discarded. The greater the maximum number of hops, the more likely the bandwidth is to be used, so the surplus bandwidth that can be used is smaller. The wireless communication standard is a standard (mode) used for wireless communication, such as IEEE802.11b, IEEE802.11g, IEEE802.11n, IEEE802.11ac, etc. The wireless repeater 20 supports multiple wireless communication standards. The wireless repeater 20 performs wireless communication using a wireless communication standard selected based on the wireless communication standard supported by the other wireless device. The maximum transfer speed may differ depending on the wireless communication standard. In the following description, "IEEE802." will be omitted. In the example shown in Figure 4, the order of transfer speed is 11ac, 11n, 11g, and 11b. Bandwidth is the channel width for wireless communication. Generally, there are bandwidths of 20 MHz, 40 MHz, 80 MHz, etc.

[0036] The video transmission setting is a setting when the wireless repeater 20 transmits video data, and is divided into a video setting and a number of units that can transmit. The video setting is a setting related to the data size per unit time of the video to be transmitted, i.e., the bit rate. The video setting includes a frame rate, a resolution, a format, and a key frame frequency. The frame rate is the number of frames contained in one second. The higher the frame rate, the higher the bit rate. The resolution is the number of pixels in both the vertical and horizontal directions of each frame. The higher the resolution, the higher the bit rate. The format indicates the compression standard of the video (including some compression of still images). The key frame frequency is the frequency at which key frames are set. Increasing the frequency of key frames may increase the bit rate. The number of units that can transmit is the number of units that can transmit video data wirelessly simultaneously by one or more wireless repeaters 20 that exist on the route for transferring the video data received by the wireless router 10 to the notebook PC 32. Here, as the number of units that can transmit increases, a larger load is placed on one wireless repeater 20, and the required bandwidth for relay communication also increases. For this reason, it is desirable to set the possible transmission number in consideration of the communication processing performance of the wireless repeater 20 and the bandwidth related to relay communication of the entire wireless communication system 1.

[0037] Hereinafter, a process of changing the video transmission setting based on the wireless communication setting will be described with reference to the flowchart illustrated in Fig. 5. The process in Fig. 5 is performed by the control unit 23 of the wireless repeater 20, for example, when starting wireless communication or when changing the wireless communication setting.

[0038] The control unit 23 first calculates the bandwidth used in the current settings of the wireless network (hereinafter, the bandwidth used) (S101). The bandwidth used is the product of the maximum number of simultaneous connections, the maximum number of hops, and the bit rate.

[0039] Next, the control unit 23 judges whether the wireless standard used by the device for communication is 11ac or not (S102). If the result in step S102 is Yes, the control unit 23 changes the video transmission settings as follows (S103). That is, the settings are changed to: resolution: FullHD, key frame frequency: 1 time / second, and number of devices that can transmit: 5. These video transmission settings are determined in advance and stored in the storage unit 24. Specifically, when the wireless standard is 11ac, the maximum bandwidth available in the wireless network is calculated, and the maximum bandwidth per wireless device is calculated from that, and the resolution, key frame frequency, and number of devices that can transmit are determined so as to approach the maximum bandwidth per device.

[0040] If the answer is No in step S102, the control unit 23 determines whether the wireless standard used by the device for communication is 11n (S104). If the answer is Yes in step S104, the control unit 23 changes the video transmission settings to the following (S105). That is, the resolution is changed to HD, the key frame frequency is changed to 1 time / 10 seconds, and the number of devices that can transmit is changed to 2. When the wireless standard is 11n, the transfer speed is lower than when the wireless standard is 11ac. Therefore, the video transmission settings when the wireless standard is 11n are set to use a smaller bandwidth than when the wireless standard is 11ac.

[0041] If the answer is No in step S104, the wireless standard used by the device itself for communication is 11g or 11b. In this case, control unit 23 changes the video transmission settings to the following (S106). That is, resolution: VGA, key frame frequency: only once, number of devices that can transmit: 1. When the wireless standard is 11g or 11b, the transfer speed is lower than when the wireless standard is 11n. Therefore, the video transmission settings when the wireless standard is 11g or 11b are such that the bandwidth used is smaller than when the wireless standard is 11n.

[0042] Next, a process of transmitting and storing video data based on the video transmission settings made in the flowchart of Fig. 5 will be described with reference to the flowchart of Fig. 6. The process of Fig. 6 is performed by the control unit 23 of the wireless repeater 20.

[0043] The video acquisition unit 22 acquires video data from the camera 31 (S201). The control unit 23 temporarily stores the acquired video data in the storage unit 24 (S202). At this point, the process of reducing the bit rate has not been performed, so the video data before the process of reducing the bit rate (i.e., the data transmitted from the camera 31) is temporarily stored in the storage unit 24.

[0044] Next, the control unit 23 judges whether or not the bit rate of the acquired video data (i.e., data size per second) is greater than the bit rate of the video transmission setting determined by the process shown in Fig. 5 (S203). That is, if the bit rate of the received video data is equal to or less than the bit rate of the video transmission setting, the necessary bit rate is realized without the need to perform a process to lower the bit rate. On the other hand, if the bit rate of the received video data is greater than the bit rate of the video transmission setting, the bandwidth will be insufficient, so a reduction process must be performed to lower the bit rate.

[0045] If the answer is Yes in step S203, the video data is converted using the video transmission settings set in the flowchart of FIG. 5, and temporarily stored in storage unit 24 (S204). This reduction process allows the bit rate of the video data to be reduced to a required value. Here, the video data converted using the video transmission settings is referred to as recorded data. If the answer is No in step S203, the process of step S204 is skipped and the next process is performed. Note that the reduction process includes not only the conversion of the video data, but also a reduction in the number of devices that can transmit.

[0046] Next, the control unit 23 determines whether there is any converted video data (recorded data) temporarily stored in the storage unit 24 (S205). If the answer is Yes in step S205, the wireless communication unit 21 transmits the recorded data to another wireless device or the notebook PC 32 (S206). If the answer is No in step S205 (i.e., if the reduction process of the video data from the camera has not been performed), the wireless communication unit 21 transmits the video data before conversion (the video data acquired from the camera 31) to the other wireless device or the notebook PC 32 (S207).

[0047] Next, a process of performing reduction processing only in some of a plurality of wireless devices will be described.

[0048] In this embodiment, the bandwidth shortage is addressed by lowering the bit rate of the video data of the camera 31. However, for important video data, it may not be desirable to lower the bit rate. For this reason, the wireless repeater 20 is capable of switching whether or not to perform the reduction process. For video data handled by a wireless repeater 20 that does not perform the reduction process, the process of lowering the bit rate is not performed. Therefore, the wireless repeater 20 transmits the video data of the data size (bit rate, quality) acquired from the camera 31 as is (without the reduction process). Note that the switching of the reduction process may be performed not for each wireless repeater 20, but for each camera 31 connected to the wireless repeater 20.

[0049] Hereinafter, a process of adjusting the band for each wireless repeater 20 will be described with reference to the flowchart of Fig. 7. The process of Fig. 7 is performed by the control unit 23 of the wireless repeater 20 (hereinafter, the target device) that performs the reduction process.

[0050] The control unit 23 calculates an appropriate target bandwidth by subtracting the excluded bandwidth from the maximum bandwidth used (S301). The maximum bandwidth used can be calculated from the wireless communication settings. Here, the excluded bandwidth is the total bandwidth used by wireless devices that do not perform reduction processing (hereinafter, excluded devices). In other words, it is the total bandwidth used by each excluded device. The bandwidth used by each excluded device can be calculated by multiplying the bit rate and the number of transmittable devices, and this bandwidth value may be notified from each excluded device or input to each target device by the administrator of the wireless communication system 1. The target bandwidth is the total bandwidth available to the target devices, and is shared among the target devices.

[0051] Hereinafter, the band for each wireless repeater before and after the band adjustment will be specifically described with reference to the table in Fig. 8. The process in Fig. 8 is performed by the control unit 23 of the wireless repeater 20.

[0052] FIG. 8 shows an example in which the bandwidths of wireless repeater A are calculated assuming that wireless repeater A is an excluded device and wireless repeater B and wireless repeater C are target devices. Here, the maximum available bandwidth is 400 Mbps. Wireless repeater A has a bit rate of 20 Mbps and there are 10 units capable of transmitting, so the available bandwidth of wireless repeater A is 200 Mbps. Since wireless repeater A is an excluded device, reduction processing for subtracting the available bandwidth is not performed. The target bandwidth (200 Mbps) is the value obtained by subtracting the excluded bandwidth (200 Mbps) from the maximum available bandwidth (400 Mbps). Note that there may be multiple excluded devices, and in this case, the target bandwidth also depends on the number of excluded devices (i.e., the number of wireless repeaters 20 that do not perform reduction processing).

[0053] Next, the control unit 23 calculates the target unit bandwidth by dividing the target bandwidth by the number of target devices (S302). The target unit bandwidth is the bandwidth available per one of the target devices. In the example shown in FIG. 8, the target unit bandwidth (100 Mbps) is calculated by dividing the target bandwidth (200 Mbps) by the number of target devices (2 devices). That is, the target unit bandwidth is calculated based on the number of target devices (i.e., the number of wireless repeaters 20 that perform reduction processing). The number of target devices may be known by communication between the target devices, or may be input to each target device by the administrator of the wireless communication system 1.

[0054] Next, the control unit 23 judges whether the target unit bandwidth is smaller than the bandwidth used by the target device (S303). In the example shown in Fig. 8, the target unit bandwidth (100 Mbps) is smaller than the bandwidths used by the wireless repeaters B and C (each of which is 200 Mbps), so the result is Yes.

[0055] Next, the control unit 23 adjusts the bit rate and the number of transmittable units of the target device so as to match the target unit bandwidth (S304). In the example shown in FIG. 8, the bandwidth used by wireless repeaters B and C (200 Mbps) needs to match the target unit bandwidth (100 Mbps). Therefore, the number of transmittable units is reduced from 10 to 5, thereby halving the bandwidth used. In this way, the bandwidth used by wireless repeaters B and C can be matched with the target unit bandwidth. In summary, the target unit bandwidth is calculated based on conditions such as the number of excluded devices and the number of target devices. Note that the bit rate may be changed instead of or in addition to changing the number of transmittable units.

[0056] Next, another method to which the above embodiment is applied will be described. In the above embodiment, the video transmission setting is changed based on the wireless communication setting, and a reduction process is performed to reduce the bandwidth used by the wireless repeater 20. In other words, the video transmission setting is changed according to the wireless communication setting. Instead, in this method, the wireless communication setting is changed based on the video transmission setting with reference to the flowchart illustrated in FIG. 9.

[0057] A specific description will be given below. In this example, it is assumed that the bandwidth can be set in advance to 20 MHz, 40 MHz, or 80 MHz. First, the control unit 23 calculates the bandwidth used per device based on the video transmission setting (S401). The calculation method can be performed by multiplying the bit rate and the number of devices that can transmit.

[0058] Next, the control unit 23 judges whether the preset bandwidth is 80 MHz (S402). If the answer is Yes in step S402, the control unit 23 changes the wireless communication settings as follows (S403). That is, the control unit 23 changes the maximum number of simultaneous connections to 15 and the maximum number of hops to 5. This wireless communication setting is predetermined and stored in the storage unit 24. Specifically, when the bit rate is 1 Mbps, the maximum number of simultaneous connections and the maximum number of hops are set so that the bandwidth approaches 80 MHz. Note that this setting may be performed by the operator instead of by the control unit 23 based on the wireless communication settings stored in the storage unit 24.

[0059] If the answer is No in step S402, the control unit 23 judges whether the preset bandwidth is 40 MHz or not (S404). If the answer is Yes in step S404, the control unit 23 changes the wireless communication settings as follows (S405). That is, the control unit 23 changes the maximum number of simultaneous connections to 10 and the maximum number of hops to 4. In other words, when the bandwidth is 40 MHz, the maximum number of simultaneous connections and the maximum number of hops are set so that the bandwidth approaches 40 MHz.

[0060] If the answer is No in step S404, that is, if the preset bandwidth is 20 MHz, the control unit 23 changes the wireless communication settings as follows (S406): the maximum number of simultaneous connections is 6, and the maximum number of hops is 3. In other words, if the bandwidth is 20 MHz, the maximum number of simultaneous connections and the maximum number of hops are set so that the bandwidth approaches 20 MHz.

[0061] In this way, if the bandwidth is small, the number of simultaneous connections and the maximum number of hops are limited accordingly, and an appropriate number of simultaneous connections and maximum number of hops are set according to the bandwidth.

[0062] In this way, the wireless communication settings can be changed in accordance with the video transmission settings. In this embodiment, the bandwidth is used as the video transmission setting, but other values ​​(for example, wireless communication standards) may be used.

[0063] As described above, the video transmission device (wireless repeater 20) of the present embodiment includes a wireless communication unit 21, a video acquisition unit 22, and a control unit 23. The wireless communication unit 21 performs wireless communication with the wireless router 10 or another wireless repeater 20. The video acquisition unit 22 acquires video data captured and generated by the camera 31 (video acquisition process, video acquisition step). The control unit 23 performs reduction processing to reduce the bandwidth used by the wireless communication unit 21 by changing the bit rate or the number of transmittable units of the video data based on the wireless communication settings of the wireless network (reduction processing process, reduction processing step), and transmits the video data via the wireless communication unit 21 (transmission process, transmission step). The video transmission program is executed by the wireless repeater 20, thereby performing the above-mentioned video transmission method.

[0064] This makes it possible to reduce the bandwidth used by the wireless communication unit 21 based on the wireless communication settings of the wireless network using multiple wireless repeaters 20 (i.e., taking into account the influence of relayed communication between wireless devices). As a result, the bandwidth used by the video transmission device can be kept within an appropriate range.

[0065] The video transmission device of this embodiment includes a storage unit 24. The storage unit 24 stores wireless communication settings and video transmission settings together with the video data acquired by the video acquisition unit 22. When the control unit 23 changes the bit rate, the control unit 23 converts the video data stored in the storage unit 24 based on the video transmission settings, and transmits the converted video data via the wireless communication unit 21.

[0066] This makes it possible to reduce bandwidth usage by transmitting the converted video data while storing the pre-conversion high-quality video data in the storage unit 24.

[0067] In the moving image transmission device of this embodiment, the control unit 23 changes the bit rate by changing at least one of the frame rate, the resolution, the moving image format, and the key frame frequency.

[0068] This allows the bitrate to be varied in a variety of ways.

[0069] In the video transmission device of this embodiment, the wireless communication settings used by the control unit 23 to change the bit rate or the number of transmittable devices include at least the maximum number of simultaneous connections and the maximum number of hops between the wireless devices that make up the wireless network.

[0070] This makes it possible to change to an appropriate bit rate or number of transmittable devices based on information that is specific to wireless relay communication and that affects the amount of bandwidth used.

[0071] In the moving image transmission device of the present embodiment, the wireless communication settings used by the control unit 23 to change the bit rate or the number of transmittable devices include at least one of the wireless communication standard and the bandwidth used in the wireless network.

[0072] This makes it possible to change to an appropriate bit rate or number of transmittable devices based on information that affects the size of the bandwidth available for wireless relay communication.

[0073] In the moving image transmission device of this embodiment, it is possible to switch whether or not to execute the reduction process.

[0074] When important video data is being handled, the reduction process is not executed, thereby making it possible to transmit high quality video data.

[0075] In the video transmission device of this embodiment, at least one wireless repeater 20 can switch whether to execute the reduction process. If there is another wireless repeater 20 that does not execute the reduction process, the control unit 23 changes the bit rate of the video data or the number of transmittable units based on the number of other wireless repeaters 20 in the wireless network that do not execute the reduction process and the number of wireless repeaters 20 (including the own repeater) that execute the reduction process in the wireless network.

[0076] It is possible to suppress a shortage of bandwidth while allowing other wireless repeaters 20 that do not perform the reduction process to transmit high quality video data.

[0077] Although the preferred embodiment of the present invention has been described above, the above configuration can be modified, for example, as follows.

[0078] The processing performed by the wireless repeater 20 in the above embodiment may be performed by the wireless router 10. In other words, the wireless router 10 may be a video transmission device.

[0079] The flowcharts shown in the above embodiment are merely examples, and some processes may be omitted, some processes may be changed, or new processes may be added. For example, in the flowchart of FIG. 5, if a wireless standard is defined, the process of determining the wireless standard may be omitted, and the video transmission settings may be changed to those according to the defined wireless standard. [Explanation of symbols]

[0080] 1. Wireless communication systems 10. Wireless Router 20 Wireless repeater (video transmission device) 21 Wireless Communication Department 22 Video Acquisition Section 23 Control Unit 24 Memory section 31 Camera 32 Notebook PC

Claims

1. In a wireless network including a wireless router and a wireless device including a plurality of wireless repeaters, a video transmission device corresponding to one of the wireless repeaters, a wireless communication unit that performs wireless communication with the wireless router or another wireless repeater; a video acquisition unit that acquires video data captured and generated by a camera; a control unit that performs a reduction process of reducing a bandwidth used by the wireless communication unit by changing a bit rate or a number of devices that can transmit the video data based on a wireless communication setting of the wireless network, and transmits the video data via the wireless communication unit; A video transmission device comprising:

2. The video transmission device according to claim 1, a storage unit that stores the wireless communication setting and the video transmission setting together with the video data acquired by the video acquisition unit, A video transmission device characterized in that when the control unit changes the bit rate, the control unit converts the video data stored in the memory unit based on the video transmission settings, and transmits the converted video data via the wireless communication unit.

3. The video transmission device according to claim 1, The video transmission device, wherein the control unit changes the bit rate by changing at least one of a frame rate, a resolution, a video format, and a key frame frequency.

4. The video transmission device according to claim 1, A video transmission device characterized in that the wireless communication settings used by the control unit to change the bit rate or the number of transmittable devices include at least the maximum number of simultaneous connections and the maximum number of hops between the wireless devices that make up the wireless network.

5. The video transmission device according to claim 1, A video transmission device characterized in that the wireless communication settings used by the control unit to change the bit rate or the number of transmittable devices include at least one of the wireless communication standard and bandwidth used in the wireless network.

6. The video transmission device according to claim 1, A moving image transmitting device capable of switching whether or not the reduction process is executed.

7. The video transmission device according to claim 1, At least one of the wireless repeaters is capable of switching whether or not to execute the reduction process, A video transmission device characterized in that, when there are other wireless repeaters that do not perform the reduction processing, the control unit changes the bit rate of the video data or the number of wireless repeaters that can be transmitted based on the number of wireless repeaters in the wireless network that do not perform the reduction processing and the number of wireless repeaters in the wireless network (including the same device) that perform the reduction processing.

8. A video transmission method for wirelessly transmitting video over a wireless network including a wireless router and a plurality of wireless repeaters, comprising: A video acquisition step of acquiring video data captured and generated by a camera; a reduction processing step of performing a reduction processing to reduce a bandwidth used by the wireless repeater by changing a bit rate or a number of transmittable devices of the video data based on a wireless communication setting of the wireless network; a transmitting step of wirelessly transmitting the video data using the wireless repeater; A video transmission method comprising:

9. A video transmission program for wirelessly transmitting video over a wireless network including a wireless router and a plurality of wireless repeaters, The wireless repeater, A video acquisition step of acquiring video data captured and generated by a camera; a reduction processing step of performing a reduction processing to reduce a bandwidth used by the wireless repeater by changing a bit rate or a number of transmittable devices of the video data based on a wireless communication setting of the wireless network; a transmitting step of wirelessly transmitting the video data using the wireless repeater; A video transmission program that causes a user to execute the steps described above.

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