Video transmission device, video transmission method, and computer program

Abstract

To provide a video transmission device capable of reducing the possibility of failure in reconnection while reducing the load in communication with a transmission destination device. [Solution] The video transmitting device includes a transmitting means for transmitting video data to a destination device via a network, a determining means for determining the load level of the network in communication with the destination device, a determining means for determining, when a disconnection of the connection with the destination device is detected, at least one of a reconnection period, a reconnection interval, and the number of reconnections based on the load level at the time of the disconnection, and a control means for transmitting a reconnection request to the destination device based on at least one of the reconnection period, the reconnection interval, and the number of reconnections determined by the determining means.

Description

[Technical Field]

[0001] The present invention relates to a video transmission device, a video transmission method, a computer program, and the like. [Background technology]

[0002] When streaming video in real time between a client and a server over a network, the use of the same network by an unspecified number of people can limit the network bandwidth, cause packet loss, etc., and the streaming can stop or become disrupted. In this case, the server may determine that it cannot continue streaming normally and cut off the connection.

[0003] Therefore, there is a function to automatically reconnect from the client to the server after disconnection. In Patent Document 1, control is performed to automatically reconnect when disconnection occurs due to deterioration of the field strength of the wireless line in wireless data communication. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-275110 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when the client receives a disconnection message from the server, it cannot determine the cause, such as whether the user performed a stop operation on the server's UI to end the broadcast, or whether the server disconnected due to increased network load.

[0006] Therefore, even when a user intentionally disconnects a broadcast and stops it from the server's UI, the client repeatedly requests a reconnection from the server. At this time, the server returns an IP-level error response (ICMP port unreachable) every time it receives a reconnection request, placing a burden on the server.

[0007] Also, if the network load increases and a disconnection occurs, there is a possibility that the connection will not be established if the reconnection period is too short. However, the period during which the client sends a reconnection request is fixed.

[0008] Therefore, when a client detects a disconnection from the server, it sends a reconnection request to the server at a predetermined interval, placing a load on the server. Also, there is a problem that the reconnection request is sent only for a short time, and the client is unable to connect to the server.

[0009] Therefore, one object of the present invention is to provide a video transmission device that can reduce the possibility of reconnection failure while reducing the load on communication with a transmission destination device. [Means for solving the problem]

[0010] In order to achieve the above object, a video transmission device according to an embodiment includes: a transmitting means for transmitting the video data to a destination device via a network; a determination means for determining a load level of a network in communication with the destination device; a determination means for determining, when a disconnection of the connection with the destination device is detected, at least one of a reconnection period, a reconnection interval, and a number of reconnection attempts based on the load level at the time of the disconnection; and a control means for transmitting a reconnection request to the destination device based on at least one of the reconnection period, the reconnection interval, and the number of reconnections determined by the determination means. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a video transmission device that can reduce the possibility of reconnection failure while reducing the load on communication with a transmission destination device. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a diagram illustrating an example of a network configuration according to a first embodiment of the present invention. [Figure 2] 1 is a functional block diagram showing an example of the internal configuration of a camera 1000 according to a first embodiment of the present invention. [Figure 3] 2 is a functional block diagram showing an example of the internal configuration of a server device 2000 according to the first embodiment of the present invention. FIG. [Figure 4] 10 is a flowchart showing an example of an automatic reconnection process using packet loss in video transmission according to the first embodiment of the present invention. [Figure 5] 10 is a flowchart showing an example of a process for determining a period for transmitting a reconnection request using packet loss in step S4004. [Figure 6] 10 is a flowchart showing an example of an automatic reconnection process using an estimated bandwidth for video transmission by the camera 1000 according to the second embodiment of the present invention. [Figure 7] 10 is a flowchart illustrating an example of a process for determining a period for transmitting a reconnection request using an estimated bandwidth according to the second embodiment of the present invention. [Figure 8] 10 is a flowchart showing an example of an automatic reconnection process using ACK and NAK received from a server according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiment. In each drawing, the same members or elements are given the same reference numerals, and duplicated descriptions will be omitted or simplified.

[0014] <Embodiment 1> A video transmitting device according to a first embodiment of the present invention will be described below with reference to Figures 1 to 5. Figure 1 is a diagram showing an example of a network configuration according to the first embodiment of the present invention.

[0015] The system in this embodiment is made up of a camera 1000, a server device 2000, a network 3000, etc. The camera 1000 can transmit video data to the server device 2000 via the network 3000, and functions as a video transmission device.

[0016] 1 is an example of an information processing device according to the present invention, and various modifications and changes are possible within the scope of the present invention. For example, although the example of a camera 1000 is given as a video transmission device, the device is not limited to a camera and may be, for example, a video recording / playback device or a server, as long as it is capable of transmitting video data via a network.

[0017] Fig. 2 is a functional block diagram showing an example of the internal configuration of the camera 1000 according to the first embodiment of the present invention. Note that some of the functional blocks shown in Fig. 2 are realized by causing a CPU or the like serving as a computer included in the camera 1000 to execute a computer program stored in a memory serving as a storage medium.

[0018] However, some or all of these functions may be implemented by hardware, such as a dedicated circuit (ASIC) or a processor (reconfigurable processor, DSP).

[0019] 2 may not be contained in the same housing, but may be configured as separate devices connected to each other via signal paths. The above explanation regarding FIG. 2 also applies to the server device shown in FIG. 3.

[0020] 2, reference numeral 1001 denotes a control unit. The control unit 1001 has a built-in CPU and the like as a computer, and functions as a control means that controls the operation of each part of the entire device based on a computer program stored in a storage unit 1002 (memory) as a storage medium.

[0021] A storage unit 1002 is used as a storage area for various data, such as a storage area for computer programs executed by the control unit 1001 and a work area during execution of the computer programs.

[0022] An imaging unit 1003 includes, for example, a CMOS image sensor, and converts the analog signal obtained by capturing an image of a subject into digital data, which is output to the storage unit 1002 as a captured image.

[0023] Reference numeral 1004 denotes a communication unit. The communication unit 1004 transmits video data and various setting values ​​to the server device 2000 using a video transmission protocol SRT (Secure Reliable Transport) via the network 3000. Note that the communication unit 1004 uses SRT as the video transmission protocol, but is not limited to this.

[0024] Furthermore, the communication unit 1004 is used to measure communication information such as packet loss, estimated bandwidth, ACK, NAK, etc. when receiving various setting values ​​and confirmation responses.

[0025] Reference numeral 1005 denotes a reconnection request transmission period control unit. When transmitting reconnection request data to the server device 2000, the control unit controls the transmission period of the reconnection request based on the communication information obtained by the communication unit 1004. In other words, the reconnection request is repeated at a predetermined interval until this period has elapsed.

[0026] FIG. 3 is a functional block diagram showing an example of the internal configuration of the server device 2000 according to the first embodiment of the present invention.

[0027] Reference numeral 2001 denotes a control unit. The control unit 2001 has a built-in CPU and the like as a computer, and functions as a control means for controlling the operation of each unit of the entire server device based on a computer program stored in a storage unit 2002 (memory) as a storage medium.

[0028] A storage unit 2002 is used as a storage area for various data, such as a storage area for computer programs executed mainly by the control unit 2001 and a work area during execution of the computer programs.

[0029] An output unit 2003 is configured by, for example, an LCD, an organic EL display, or the like, and outputs various setting screens and a viewer for the video received from the camera 1000 to the user of the server device 2000.

[0030] An input unit 2004 is configured with, for example, buttons, a cross key, a touch panel, a mouse, etc., and notifies the control unit 2001 of the content of screen operations performed by the user.

[0031] Reference numeral 2005 denotes a communication unit. The communication unit 2005 is used to receive video data and various setting values ​​from the camera 1000 and to transmit various setting values ​​and confirmation responses via the network 3000 using a video transmission protocol such as SRT. Note that the communication unit 2005 uses SRT as the video transmission protocol, but is not limited to this.

[0032] 4 is a flowchart showing an example of automatic reconnection processing using packet loss in video transmission according to the first embodiment of the present invention. Note that the operation of each step in the flowchart of FIG. 4 is performed sequentially by a CPU or the like serving as a computer in the camera 1000 executing a computer program stored in memory.

[0033] In step S4001, the camera 1000 transmits video at an arbitrary transmission bit rate to the server device 2000. Note that step S4001 here functions as a transmission step (transmission means) that transmits video data to a destination device (external device) via the network. Next, in step S4002, the number of packet losses per unit time is measured and saved using the SRT function.

[0034] In step S4003, it is determined whether a disconnection from the server has been detected. If a disconnection has not been detected, video data is transmitted in step S4001. If a disconnection is detected, in step S4004, a period for periodically continuing reconnection is determined using packet loss.

[0035] The processing of step S4004 will be described later using the flowchart in Fig. 5. In step S4005, it is determined whether the period determined in step S4004 has elapsed. If the period determined has elapsed, the reconnection has not been successful, but the process is abandoned and the automatic reconnection processing flow in Fig. 4 ends. However, after the end, the automatic reconnection processing flow in Fig. 4 can be resumed by the user's operation.

[0036] If it is determined in step S4005 that the determined period has not elapsed, a reconnection request is sent in step S4006. In step S4007, it is determined whether the reconnection was successful. If not, the process returns to step S4005. If successful, the automatic reconnection process shown in FIG. 4 ends.

[0037] 5 is a flowchart showing an example of the process of determining the period for continuing transmission of a reconnection request using packet loss, etc., in step S4004. Note that the operation of each step in the flowchart of FIG. 5 is performed sequentially by a CPU or the like serving as a computer within camera 1000 executing a computer program stored in memory.

[0038] In step S5001, the number of packet losses before disconnection that was saved in step S4002 is checked, and in step S5002, it is determined whether the number of packet losses is equal to or less than a predetermined value.

[0039] If the packet loss is below a predetermined value, it is highly likely that the user performed a stop operation to disconnect rather than that the network load was the cause, so in step S5003 it is decided to reconnect only once to reduce the load on the server. However, if the determination in step S5002 is Yes, it is also possible not to reconnect.

[0040] If it is determined in step S5002 that the packet loss is greater than the predetermined value, it is determined in step S5004 whether the packet loss is equal to or less than a predetermined threshold. If the packet loss is equal to or less than the predetermined threshold, it is determined in step S5005 that reconnection will be repeated for a certain period of time. For example, reconnection will be repeated for 30 seconds at 5-second intervals.

[0041] If it is determined in step S5004 that the packet loss is greater than the predetermined threshold, the network load at the time of disconnection is higher, and therefore the disconnection is likely to have been caused by the network load. In other words, since it is likely that the server is still waiting for a connection, in step S5006 it is determined that reconnection will be repeated for a longer period of time. For example, reconnection will be repeated at one-second intervals for five minutes.

[0042] Since a high network load increases the time it takes to restore the network, in this embodiment, reconnection is repeated for a longer period of time to increase the likelihood of successful reconnection. Here, the threshold value is a value for determining the level of network load, and may be a fixed value determined in advance, or may be dynamically determined during video transmission, such as by calculating the average number of packet losses every fixed period and adding or multiplying that average by a predetermined value to set the threshold value.

[0043] That is, when comparing the load level with a predetermined threshold, the threshold may be a fixed value or a value that is dynamically determined depending on the network conditions.

[0044] Alternatively, multiple thresholds may be set in step S5004 to determine multiple levels of network load and determine the reconnection period in more detail. That is, the network load level may be determined in multiple stages by comparing the load level with multiple thresholds.

[0045] Here, the above steps S5002 and S5004 function as a determination step (determination means) for determining the load level of the network in communication with the destination device.

[0046] In addition to or instead of determining the reconnection period (reconnection period), the reconnection interval (reconnection interval) may be shortened or the number of reconnections per given time (number of reconnections / reconnection frequency) may be increased. That is, the higher the load level, the longer the reconnection period, the shorter the reconnection interval, or the more reconnections there may be.

[0047] That is, if the load level is greater than a predetermined threshold, it may be determined to lengthen the reconnection period during which a reconnection request is repeated at a predetermined interval.Also, if the load level is greater than a predetermined threshold, it may be determined to shorten the reconnection interval during which a reconnection request is repeated at a predetermined interval.Also, if the load level is greater than a predetermined threshold, it may be determined to increase the number of reconnections per predetermined time.

[0048] In addition, steps S5003, S5005, S5006, etc. function as a decision step (decision means) that, when a disconnection of the connection with the destination device is detected, decides at least one of the reconnection period, reconnection interval, and number of reconnections based on the load level at the time of the disconnection.

[0049] Also, a reconnection request may be sent to the destination device in step S4006 of Fig. 4 based on at least one of the reconnection period, reconnection interval, and number of reconnections determined in the flow of Fig. 5. That is, step S4006 functions as a control step (control means) that sends a reconnection request to the destination device based on at least one of the determined reconnection period, reconnection interval, and number of reconnections.

[0050] As described above, in this embodiment, the process of determining the reconnection period determines that the disconnection is likely due to network load when the number of packet losses before the disconnection is large, and increases at least one of the reconnection period, reconnection interval, and number of reconnections.

[0051] This makes it possible to reduce the load on the server by shortening the reconnection period when it is highly likely that the user performed a stop operation.On the other hand, when it is highly likely that the disconnection was caused by network load, it is possible to reduce the possibility of reconnection failure by lengthening the reconnection period, shortening the reconnection interval, or increasing the number of reconnection attempts (frequency).

[0052] Furthermore, for example, other values ​​such as estimated bandwidth, ACK, NAK, round trip time, etc. may be used instead of packet loss as statistical information representing the method of determining the period, interval, number of times, and threshold for reconnection, and the network load level.

[0053] For example, the more packet loss there is, the higher the load level is determined to be. When packet loss is used, the load level can be determined as a value based on the number or amount of packet loss per predetermined time. Also, the longer the round trip time, the higher the load level is determined to be.

[0054] When using the round trip time, the round trip time itself or a value based on the round trip time can be used as the load level. There are various methods for determining the degree of load on network communication. Therefore, the network load level can be determined by various other methods.

[0055] The load level may be determined based on at least one of the number of packet losses, the network bandwidth, the round trip time, and the response packet sent from the destination device. Also, the video transmission protocol is not limited to SRT, and other protocols may be used, and audio may be transmitted in addition to video.

[0056] <Embodiment 2> A video transmission device according to a second embodiment of the present invention will be described below with reference to Figures 1 to 3 and 6 to 8. Note that the network configuration in Figure 1, the internal configuration of the camera 1000 in Figure 2, and the internal configuration of the server device 2000 in Figure 3 are the same as those in the first embodiment, and therefore descriptions thereof will be omitted.

[0057] In the first embodiment, the reconnection period is lengthened, the reconnection interval is shortened, and the number of reconnections (frequency) per given time is increased based on packet loss. In this embodiment, a method for determining the reconnection period using communication information that indicates the network load other than packet loss will be described with reference to Figs. 6, 7, and 8.

[0058] FIG. 6 is a flowchart showing an example of an automatic reconnection process using an estimated bandwidth for video transmission by the camera 1000 according to the second embodiment of the present invention.

[0059] FIG. 7 is a flowchart showing an example of a process for determining a period for transmitting a reconnection request using an estimated bandwidth according to the second embodiment of the present invention.

[0060] FIG. 8 is a flowchart showing an example of an automatic reconnection process using ACK and NAK received from the server according to the second embodiment of the present invention.

[0061] The operations of the steps in the flowcharts of FIGS. 6 to 8 are performed sequentially by a CPU or the like serving as a computer within the camera 1000 executing a computer program stored in memory.

[0062] In FIG. 6, steps S6001, S6003, and S6005 to S6007 are the same as steps S4001, S4003, and S4005 to S4007 in the flowchart of FIG. 4, and therefore description thereof will be omitted.

[0063] In step S6002, the current estimated bandwidth is measured and saved. In step S6003, if a disconnection from the server is detected, in step S6004, the estimated bandwidth estimated in step S6002 is used to determine the period for reconnection.

[0064] An example of processing for determining a period for reconnection using the estimated bandwidth in step S6004 will be described using the flowchart in Fig. 7. Steps S7003, S7005, and S7006 are the same as steps S4003, S4005, and S4006 in the flowchart in Fig. 4, so their description will be omitted.

[0065] In step S7001, the estimated bandwidth at the time of disconnection saved in step S6002 is checked. In step S7002, it is determined whether the estimated bandwidth is significantly greater than the target bit rate at the time of disconnection. Specifically, it is determined whether the estimated bandwidth is greater than, for example, the target bit rate at the time of disconnection multiplied by a predetermined value (a value greater than 1).

[0066] The target bit rate represents the target value of the bit rate when the camera attempts to transmit video data. If the estimated bandwidth is much larger than the target bit rate, it is highly likely that the user performed a stop operation to disconnect rather than that the network load was the cause, so in step S7003 it is decided to reconnect only once to reduce the load on the server. However, it is also possible not to reconnect.

[0067] If the answer is No in step S7002, that is, if it is determined that the estimated bandwidth is not much greater than the target bit rate, then in step S7004 it is determined whether the estimated bandwidth is equal to or greater than the target bit rate at the time of disconnection.

[0068] If the estimated bandwidth is equal to or greater than the target bit rate at the time of disconnection, it is determined in step S7005 that reconnection will be repeated for a certain period of time. On the other hand, if the estimated bandwidth is smaller than the target bit rate, the network load at the time of disconnection is high, so it is determined in step S7006 that reconnection will be repeated for a longer period than in step S7005. Alternatively, it may be determined to shorten the reconnection interval or increase the number of reconnection attempts (frequency). All of these may be performed.

[0069] As described above, in this embodiment, in the automatic reconnection process using the estimated bandwidth, the target bit rate at the time of disconnection is used as a threshold and compared with the estimated bandwidth. This determines the level of network load and changes at least one of the reconnection period, reconnection interval, and number of reconnections. Decided to do so.

[0070] Next, an example of automatic reconnection processing using ACK and NAK will be described with reference to the flowchart of FIG.

[0071] 8, in step S8001, the camera 1000 transmits video at an arbitrary transmission bit rate to the server device 2000. In step S8002, after a certain period of time has passed, it is determined whether an ACK or NAK has arrived from the server.

[0072] If an ACK or NAK has been received from the server, video data is sent in step S8001. If an ACK or NAK has not been received from the server, the camera disconnects the connection in step S8003. In this case, since there has been no response from the server for a certain period of time, it is highly likely that the server is down and not accepting connections.

[0073] Therefore, in order to reduce the load on the server, in step S8004, reconnection is not performed, or reconnection is repeated within a shorter period than usual, or reconnection is repeated at longer time intervals than usual, and then the automatic reconnection processing flow in Figure 8 is terminated.

[0074] That is, if a response packet is not sent from the destination device for a predetermined period of time before a disconnection is detected, in step S8004, reconnection is not performed, or the period for which reconnection continues is shortened, or the time interval for sending reconnection requests is lengthened.

[0075] However, when reconnection is successful, the automatic reconnection processing flow in Fig. 8 ends. If reconnection fails after the automatic reconnection processing flow in Fig. 8 ends, the automatic reconnection processing flow in Fig. 8 can be restarted by a user operation. In other words, if connection to the destination device cannot be established during the period in which a reconnection request is sent, the process for reconnection can be started by a user operation.

[0076] As explained above, in the automatic reconnection process using ACK and NAK according to this embodiment, if an ACK or NAK is not received from the server within a certain period of time, it is determined that the server is down, and the connection is severed while reconnection process is performed to reduce the load on the server. This makes it possible to reduce the load on the down server.

[0077] For example, other communication information may be used as a value representing the network load, or other response packets may be used instead of ACK or NAK, and the video transmission protocol may not be limited to SRT. Audio may also be transmitted in addition to video.

[0078] In the second embodiment, we have explained a method of using an estimated bandwidth, ACK, and NAK as communication information for automatic reconnection processing in video transmission. This makes it possible to shorten the reconnection period and reduce the load on the server when there is a high possibility that the user has performed a stop operation.

[0079] Also, if there is a high possibility that the disconnection was caused by network load, the reconnection period can be extended to reduce the possibility of reconnection failure.Also, if there is a high possibility that the server has gone down, the load on the server can be reduced by not reconnecting, shortening the reconnection period, or lengthening the reconnection interval.

[0080] The present invention has been described in detail above based on its preferred embodiments, but the present invention is not limited to the above embodiments, and various modifications and combinations of the above embodiments are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

[0081] The present invention also includes those that realize the functions of the above embodiments using, for example, at least one processor such as a CPU, memory, or circuit (for example, ASIC). Also, multiple processors may be used to perform distributed processing.

[0082] In order to realize some or all of the control in the above-described embodiment, a computer program that realizes the functions of the above-described embodiment may be supplied to a video transmitting device or the like via a network or various storage media.

[0083] The computer (or CPU, MPU, etc.) in the video transmission device or the like may then read and execute the program. In this case, the program and the storage medium storing the program constitute the present invention. The present invention also includes the following combinations.

[0084] (Configuration 1) A video transmitting device characterized by having: a transmitting means for transmitting video data to a destination device via a network; a determining means for determining the load level of the network in communication with the destination device; a determining means for determining, when a disconnection of the connection with the destination device is detected, at least one of a reconnection period, a reconnection interval, and a number of reconnection attempts based on the load level at the time of the disconnection; and a control means for transmitting a reconnection request to the destination device based on at least one of the reconnection period, the reconnection interval, and the number of reconnection attempts determined by the determining means.

[0085] (Configuration 2) The video transmitting device according to configuration 1, characterized in that the determination means determines to lengthen the reconnection period during which the reconnection request is repeated at predetermined intervals when the load level is greater than a predetermined threshold.

[0086] (Configuration 3) The video transmitting device according to configuration 1 or 2, characterized in that the determination means determines to shorten the reconnection interval at which the reconnection request is repeated at a predetermined interval when the load level is greater than a predetermined threshold.

[0087] (Configuration 4) The video transmitting device according to any one of configurations 1 to 3, wherein the determining means determines to increase the number of reconnections per predetermined time when the load level is greater than a predetermined threshold.

[0088] (Configuration 5) A video transmitting device described in any one of configurations 1 to 4, characterized in that the load level is determined based on at least one of the number of packet losses, network bandwidth, round trip time, and response packets sent from the destination device.

[0089] (Configuration 6) A video transmission device described in any one of configurations 1 to 5, characterized in that the determination means compares the load level with a predetermined threshold, and the threshold is a fixed value or a value dynamically determined depending on the network conditions.

[0090] (Configuration 7) The video transmitting device according to configuration 6, wherein the determining means determines the load level of the network in a plurality of stages by comparing the load level with a plurality of thresholds.

[0091] (Configuration 8) A video transmission device described in any one of configurations 1 to 7, characterized in that the control means does not reconnect, or reduces the reconnection period, or increases the time interval for sending the reconnection request if a response packet is not sent from the destination device for a predetermined time before detecting the disconnection.

[0092] (Configuration 9) A video transmitting device according to any one of configurations 1 to 8, characterized in that when a connection to the destination device cannot be established during the period in which the reconnection request is sent, the device allows a user to start processing for reconnection.

[0093] (Method) A video transmission method comprising: a transmission step of transmitting video data to a destination device via a network; a determination step of determining the load level of the network in communication with the destination device; a determination step of determining, when a disconnection of the connection with the destination device is detected, at least one of a reconnection period, a reconnection interval, and a number of reconnection attempts based on the load level at the time of the disconnection; and a control step of transmitting a reconnection request to the destination device based on at least one of the reconnection period, the reconnection interval, and the number of reconnection attempts determined by the determination step.

[0094] (Program) A computer program for causing a computer to execute each means of the video transmission device according to any one of configurations 1 to 9. [Explanation of symbols]

[0095] 1000: Camera 2000: Client device 3000: Network

Claims

1. a transmitting means for transmitting the video data to a destination device via a network; a determination means for determining a load level of a network in communication with the destination device; a determination means for determining, when a disconnection of the connection with the destination device is detected, at least one of a reconnection period, a reconnection interval, and the number of reconnection attempts based on the load level at the time of the disconnection; a control means for transmitting a reconnection request to the destination device based on at least one of the reconnection period, the reconnection interval, and the number of reconnections determined by the determination means.

2. 2. The video transmission device according to claim 1, wherein the determining means determines to lengthen the reconnection period during which the reconnection request is repeated at predetermined intervals when the load level is greater than a predetermined threshold.

3. 2. The video transmission device according to claim 1, wherein the determining means determines to shorten the reconnection interval at which the reconnection request is repeated at a predetermined interval when the load level is greater than a predetermined threshold.

4. 2. The video transmission device according to claim 1, wherein the determining means determines to increase the number of reconnections per predetermined time when the load level is greater than a predetermined threshold.

5. 2. The video transmission device according to claim 1, wherein the load level is determined based on at least one of the number of packet losses, network bandwidth, round trip time, and a response packet sent from the destination device.

6. The determining means compares the load level with a predetermined threshold value, 2. The video transmission device according to claim 1, wherein the threshold value is a fixed value or a value dynamically determined depending on the network conditions.

7. 7. The video transmission device according to claim 6, wherein the determining means determines the load level of the network in a plurality of stages by comparing the load level with a plurality of thresholds.

8. The video transmission device described in claim 1, characterized in that if a response packet is not sent from the destination device for a predetermined time before detecting the disconnection, the control means does not reconnect, or reduces the reconnection period, or increases the time interval for sending the reconnection request.

9. 2. The video transmission device according to claim 1, wherein if a connection to the destination device cannot be established during a period in which the reconnection request is transmitted, a process for reconnection can be initiated by a user operation.

10. a transmitting step of transmitting the video data to a destination device via a network; a determining step of determining a load level of a network in communication with the destination device; a determining step of determining, when a disconnection of the connection with the destination device is detected, at least one of a reconnection period, a reconnection interval, and a number of reconnection attempts based on the load level at the time of the disconnection; a control step of sending a reconnection request to the destination device based on at least one of the reconnection period, the reconnection interval, and the number of reconnections determined in the determination step.

11. A computer program for causing a computer to execute each means of the video transmission device according to any one of claims 1 to 9.

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