JP2020048052A - Video communication server, system, method, and program - Google Patents

Abstract

To secure a communication band for communicating a high-resolution video even when a communication band is congested.SOLUTION: A video communication server according to an embodiment includes a connection unit, a bandwidth control unit, and a transmission unit. The connection unit constantly connects a plurality of video sources and a plurality of destination terminals via a network, and enables a plurality of pieces of video data to be transmitted from the plurality of video sources to the plurality of destination terminals. The bandwidth control unit can use a higher and wider communication band for each destination terminal corresponding to each of the plurality of pieces of video data, and controls a communication bandwidth for each destination terminal according to a priority set in association with the destination terminal. The transmission unit transmits the plurality of pieces of video data to a corresponding destination terminal according to a communication band for each destination terminal.SELECTED DRAWING: Figure 4

Description

  Embodiments of the present invention relate to a video communication server, a system, a method, and a program.

  In recent years, for example, in a surveillance system using a camera installed in a store, a video communication system using a network is used. The video communication system transmits a video captured by a camera to a terminal device of a monitoring system via a network. The terminal device of the monitoring system is generally a personal computer (PC) connected to a network, and can receive an image on a Web browser of the PC. In addition, the video communication system can transmit not only video but also audio input from a microphone via a network.

  In a surveillance system, it is necessary for a user such as a surveillance manager to surely confirm a video received by a Web browser of a PC on a screen of a display and listen to received voice through a speaker of the PC. In order to realize such a reliable monitoring process, in a video communication system applied to a monitoring system, it is required to secure a band of video communication and a long session for stable transmission of video. You.

JP-A-2006-82419 JP-T-2006-517642 A

  Video communication systems applied to surveillance systems, etc., are required to secure video communication bandwidth and secure long-term sessions for stable video transmission. Also, it is desirable that dedicated video playback software be installed. However, if a video communication system dedicated to monitoring processing is used, a high cost is required to construct a monitoring system. In recent years, a video communication system to which a WebRTC method or the like capable of real-time video communication (including voice communication) is applied on a network has been attracting attention. However, it is not easy to apply this video communication system to a monitoring system or the like.

  As described above, the video communication system to which the WebRTC method or the like is applied can be applied to a monitoring system or the like without using a dedicated line or dedicated video playback software.

  However, when it becomes necessary to communicate high-resolution video data using a network, the communication band may be congested and a communication band for communicating high-resolution video may not be secured. In particular, if important and urgent video data must be sent to a terminal device such as an administrator in a hurry, it is guaranteed that such video data is always transmitted to a terminal device such as an administrator. Whether or not it is a very important issue. Further, when such video data is not real-time video data but past video data, it is important to complete downloading of this video data as soon as possible.

  The problem to be solved by the present invention is to provide a video communication server, a system, a method, and a program that can secure a communication band for communicating high-resolution video even when the communication band is congested. is there.

  The video communication server according to the present embodiment includes a connection unit, a band control unit, and a transmission unit. The connection unit constantly connects a plurality of video sources and a plurality of destination terminals via a network, and enables a plurality of video data to be transmitted from the plurality of video sources to the plurality of destination terminals. The bandwidth control unit can use a wider communication band for each destination terminal corresponding to each of the plurality of video data, and use a higher communication bandwidth for each destination terminal according to a priority set in association with the destination terminal. Control. The transmitting unit transmits the plurality of video data to a corresponding destination terminal according to a communication band for each destination terminal.

FIG. 1 is a block diagram for explaining a configuration of a video communication system according to an embodiment. FIG. 2 is a diagram showing one video source, a plurality of WebRTC servers, and one destination terminal in the system shown in FIG. 1. FIG. 3 is a block diagram showing an example of a hardware configuration of the video communication server shown in FIG. 2. FIG. 4 is an exemplary block diagram illustrating an example of a software configuration of a control unit illustrated in FIG. 3. FIG. 4 is a sequence diagram showing an example of an operation in the video communication system according to the embodiment. 9 is a flowchart illustrating an example of an operation for securing a communication band by the video communication server according to the embodiment. 9 is a flowchart illustrating an example of an operation in which the video communication server according to the embodiment transmits a video transmission completion time to a destination terminal. FIG. 6 is a sequence diagram showing an example of an operation different from that in FIG. 5 in the video communication system according to the embodiment. 9 is a flowchart illustrating an example of an operation corresponding to FIG. 8 for the video communication server according to the embodiment to secure a communication band.

  Hereinafter, an embodiment according to one aspect of the present invention (hereinafter, also referred to as “the present embodiment”) will be described with reference to the drawings. In the following embodiments, the same operation is performed for the parts with the same numbers, and the overlapping description will be omitted.

[System configuration]
First, an entire system to which a video communication server according to an embodiment is applied will be described with reference to FIG. FIG. 1 shows a video source 101 that obtains video and / or audio to create and / or accumulate video data, a WebRTC (Web-based real-time communication) server 103 according to the present embodiment, and a WebRTC server 103. 6 shows an example of an application scene of a destination terminal 104 that receives video data via a terminal. The WebRTC method (sometimes referred to as “WebRTC protocol”) adopted by the WebRTC server 103 is a technology for exchanging real-time communication using the Web. For example, if the WebRTC method is used, real-time video can be transmitted.

  The WebRTC server 103 establishes a session between a specific video source 101 and a specific destination terminal 104 via the network 102, constantly connects the video source 101 and the destination terminal 104, A communication band from the source 101 to the destination terminal 104 is secured to enable video communication and data communication. In general, the WebRTC method has a media channel and a data channel. The media channel indicates a video and audio data communication system, and this channel employs a protocol for transmitting video data and audio data in real time. The data channel indicates a communication system capable of transmitting arbitrary data, and transmits character strings and binary data (data other than video data) with low delay. Further, the WebRTC server 103 performs a signaling process when the video source 101 and the destination terminal 104 are constantly connected, and a session is established between the video source 101 and the destination terminal 104 upon receiving this process. . In the present embodiment, video data conforming to the WebRTC method is handled.

  The network 102 connects to a plurality of video sources 101, a plurality of WebRTC servers 103, and a plurality of destination terminals 104, and mediates communication between them.

  The video source 101 includes a video camera capable of capturing moving images and still images (hereinafter collectively referred to as “video”), a recorder that stores the captured moving images and still images, and a moving image data and a still image A relay device for communicating image data with the network 102 is provided. The video camera has, for example, a microphone and also acquires audio information. Here, it is assumed that the audio data may be included in the video data. That is, in the present embodiment, the video to be transmitted and received may include audio.

  The destination terminal 104 is a general computer that can communicate with the network 102, and is a terminal that has a browser and can be connected to the network 102, such as a personal computer, a smartphone, or a smart watch.

  Next, the video source 101 and the destination terminal 104 will be mainly described with reference to FIG. FIG. 2 shows one video source, a plurality of WebRTC servers, and one destination terminal in the system shown in FIG. 1 according to the present embodiment. As shown in FIG. 1, the video communication system according to the present embodiment is applied to, for example, a monitoring system, and transmits and receives video data, control data, and the like using a WebRTC server 103 and a network 102 such as the Internet as main components.

  The relay device 201 on the monitoring target side (here, the video source 101) and the client terminal 251 on the management side (here, the destination terminal 104) are connected to the network 102.

  The monitoring target (video source 101) is, for example, a store such as a convenience store, and includes a plurality of video cameras 202, a video recorder 203, and an alarm device 204 that configure a monitoring system. Note that the monitoring target side (video source 101) is an internal area of a store in the present embodiment, but may be various buildings or facilities, and the applicable range is arbitrary. The alarm device 204 includes, for example, an alarm button 205 and a pedal 206.

  The management side (here, the destination terminal 104) is, for example, an office or a home of an administrator who operates a store, and has a client terminal 251 and / or a mobile terminal 252. The client terminal 251 is, for example, a personal computer (PC), is connected to the network 102, and receives a video transmitted from the monitoring target side (video source 101) in cooperation with the WebRTC server 103. The mobile terminal 252 is different from the client terminal 251 in establishing wireless communication with the network 102, but performs substantially the same operation as the client terminal 251. The video data received by the destination terminal 104 is received from the plurality of video cameras 202, and the screen of the client terminal 251 or the mobile terminal 252 is divided into four or eight in accordance with the number of video cameras 202, and the May be displayed on the screen of the terminal.

  Each of the plurality of video cameras 202 is arranged at a place where each monitoring area in the store can be photographed, and outputs the photographed video as video data via a wired or wireless connection. Although not shown, the video and audio are output from the microphone arranged near the register in the video camera 202 or the store, or from the microphone built in the video camera 202 together with the video in the video data via a wired or wireless connection. You.

  The video recorder 203 is a storage device that records (records and records) video output from the video camera 202, and includes, for example, a hard disk drive or a solid state drive. The video recorder 203 mainly stores video data shot and recorded in the past. The past video data is usually data including high-resolution video (also referred to as “high-definition video”), and is transmitted by a request from the destination terminal 104, a request from the WebRTC server 103, or a request from the alarm device 204. Required. The video recorder 203 of this embodiment includes a so-called server function, and can transmit video data output from the video camera 202 to the network 102 via the relay device 201. More specifically, the video recorder 203 can execute live transmission (for example, using the WebRTC method) of video captured by the video camera 202, or can perform desired video data ( Typically, high-resolution video data can be extracted and transmitted.

  The alarm device 204 executes an alarm notification from the relay device 201 to the WebRTC server 103 via the network 102. The alarm device 204 outputs an alarm (warning) signal in an emergency or emergency, for example, in response to the operation of a warning button 205 or a pedal 206 arranged near a register in a store, and the WebRTC server 103. (Ie, to the corresponding destination terminal 104).

  Note that the alarm device 204 may be configured to output an alarm signal when an abnormality is detected based on an image captured by the video camera 202. Specifically, the alarm device 204 normally detects an abnormal condition when a change occurs in the video in the specific area in a situation where no change occurs in the video captured by the video camera 202 in the specific area. Is detected. For example, normally, when the specific area is an area where no person exists, and when a video taken by the video camera 202 includes a person, it is detected that an abnormality has occurred. Since this abnormality detection can be realized by software, it can be executed by the WebRTC server 103 and / or the destination terminal 104 in addition to the alarm device 204. The abnormality detection may determine whether or not the abnormality is comprehensive based on at least two of the alarm device 204, the WebRTC server 103, and the destination terminal 104.

  Further, in the present embodiment, the video communication connection of the WebRTC system or the like is automatically executed in response to the alarm issuance on the monitoring target side (video source 101) such as a store. The communication connection may be automatically executed in response to occurrence of a predetermined event.

Hereinafter, an example of abnormality detection will be specifically described.
On the monitoring target side (video source 101), in the event of an emergency in the store, when a person in charge operates the alarm button 205 or the pedal 206 to generate an alarm, the alarm device 204 outputs an alarm signal. The alarm signal from the alarm device 204 is transmitted to the network 102 by the relay device 201, and the WebRTC server 103 is notified of the alarm. On the monitoring target side (video source 101), in the event of an emergency in the store, when a person in charge operates the alarm button 205 or the pedal 206 to generate an alarm, the alarm device 204 outputs an alarm signal. The alarm signal from the alarm device 204 is transmitted to the network 102 by the relay device 201, and the WebRTC server 103 is notified of the alarm.

  When receiving the alarm notification, the WebRTC server 103 executes an automatic connection process for the client terminal 251 on the management side (the destination terminal 104) registered in advance. That is, the WebRTC server 103 activates the browser of the client terminal 251 and executes a WebRTC communication connection process via the network 102. When a WebRTC communication connection to the client terminal 251 is secured by the automatic connection processing of the WebRTC server 103, a session is secured and real-time WebRTC video communication can be performed. Thus, the video recorder 203 on the monitoring target side (video source 101) can transmit video to the client terminal 251 in real time via the relay device 201 and the network 102.

  Further, the WebRTC server 103 can also execute an automatic connection process for the selected mobile terminal 252. That is, the mobile terminal 252 receives video data in real time from the video recorder 203 on the monitoring target side (video source 101) via the relay device 201 and the network 102 by the same operation as that of the client terminal 251 described above. can do.

  The client terminal 251 has, for example, software downloaded from the WebRTC server 103 and connected to the network 102 by the WebRTC method to enable real-time video and / or audio communication. Note that the client terminal 251 may have a configuration in which the software is previously installed in a browser. The client terminal 251 receives a video transmitted in real time from the monitoring target side (video source 101) by the WebRTC method via the network 102 by a Web browser (hereinafter, referred to as a “browser”), and displays the video on a display screen. You can play with.

  The mobile terminal 252 is a mobile terminal typified by a smartphone, and has the same software as the client terminal 251 installed. By operating the mobile terminal 252, the administrator can use the Web browser to transmit a video transmitted in real time from the monitoring target side (video source 101) via the network 102 via the WebRTC method, similarly to the client terminal 251. It can be received and played on the display screen.

  On the management side (destination terminal 104), when the communication connection of the WebRTC system is secured, the administrator uses the browser of the client terminal 251 to display live video (including audio) captured by the video camera 202 in the store. The received video data can be confirmed on the display screen. The audio can be output from the speaker of the client terminal 251. Further, the administrator can receive video data recorded in the video recorder 203 (that is, video data recorded in the past) on the browser of the client terminal 251 and check it on the screen of the display. Normally, the client terminal 251 can download the video data recorded in the past (higher resolution video than the live video) and play it back on the display of the client terminal 251 after the download is completed for confirmation. Also, the client terminal 251 plays back (stream plays) the video data recorded in the past on the screen of the client terminal 251 while receiving the video data using a communication band wider than the communication band for the normal live video. May be. In the case of stream reproduction, it can be confirmed at the same time as reception. On the other hand, when reproducing the downloaded video data, it is possible to move to an arbitrary shooting frame.

  The operation of the client terminal 251 on the management side (destination terminal 104) will be briefly described. When the client terminal 251 is powered on and a function such as a browser is running, a WebRTC communication connection is secured by the automatic connection processing of the WebRTC server 103. That is, the client terminal 251 can perform real-time WebRTC video communication with the monitoring target (video source 101).

  The client terminal 251 can receive and reproduce video data transmitted in real time from the video recorder 203 on the monitoring target side (video source 101) via the relay device 201 and the network 102. The sound is output from a speaker built in the client terminal 251. Specifically, the client terminal 251 can receive video data including live video captured by the video camera 202 in the store on the browser, and reproduce the video on the screen of the display. In addition, the client terminal 251 can receive the video (including the recorded audio) recorded on the video recorder 203 on the browser and reproduce the video on the screen of the display.

[Hardware configuration of video communication server]
Next, an example of a hardware configuration of the WebRTC server 103 according to the present embodiment will be described with reference to FIG.
As shown in FIG. 3, the WebRTC server 103 according to the present embodiment includes a communication interface 301, a storage unit 302, an input device 303, an output device 304, a control unit 305, a timing device 306, a power supply unit 307, and an external interface 308. Includes an electrically connected computer. In FIG. 3, the communication interface and the external interface are described as “communication I / F” and “external I / F”, respectively.

  The control unit 305 includes a central processing unit (CPU), a random access memory (RAM), a read only memory (ROM), and the like, and controls each component according to information processing. The storage unit 302 is, for example, an auxiliary storage device such as a hard disk drive or a solid state drive. The storage unit 302 executes a communication band securing execution program for securing a communication band in the WebRTC server 103, which is executed by the control unit 305, and the video source 101. And a transmission completion time calculation program for calculating a time at which a process of transmitting high-resolution video data obtained from the video recorder 203 to the destination terminal 104 is completed, and / or control data, video, and audio obtained by the WebRTC server 103. Data or the like may be stored.

  The communication band securing execution program for securing the communication band transmits other video data to secure a communication band for transmitting specific data (for the purpose of communicating high-resolution video data, for example). This is a program for executing a process for reducing the communication band (FIG. 6) or a process for allowing another WebRTC server 103 to accommodate the communication band (FIG. 9). Further, the transmission completion time calculation program is for transmitting the high resolution video data stored in the video recorder 203 of the video source 101 to the destination terminal 104 and calculating the time at which the transmission of the high resolution video data is completed. This is a program for executing processing (FIG. 7).

  The communication interface 301 is, for example, a short-range wireless communication (for example, Bluetooth (registered trademark)) module, a wired LAN (Local Area Network) module, a wireless LAN module, or the like, for performing wired or wireless communication via the network 102. Interface. The communication interface 301 connects the WebRTC server 103 to the video source 101 (for example, the relay device 201, the video camera 202, the video recorder 203, and the alarm device 204) and the destination terminal 104 (for example, the client terminal 251 and / or the mobile terminal). 252). The communication interface 301 is controlled by the control unit 305. The communication interface 301 transfers information received from an external device (for example, the video source 101) via the network to the control unit 305. Communication via the network 102 may be wireless or wired. Note that the communication interface 301 may be able to transmit information to an external device via a network. The network may be an internetwork including the Internet or another type of network such as a WAN (Wide Area Network).

The storage unit 302 stores the information of the program or the like electrically, magnetically, optically, mechanically, or chemically so that a computer or other device and a machine or the like can read the information such as the recorded program. It is a medium that accumulates by action. The WebRTC server 103 may acquire, from the storage unit 302, a communication band securing execution program for securing a communication band, a transmission completion time calculation program, control data acquired by the WebRTC server 103, and the like.
Further, the storage unit 302 stores, for each destination terminal 104, a priority indicating an authority to preferentially use the communication band. For example, a wider communication band can be used as the priority is higher. This priority is set in advance by a contract with the administrator of the destination terminal 104, for example. Of course, it is also possible to change the contract between the manager and the communication service provider in real time to raise or lower the priority. The priority may be set for each WebRTC server 103, and the storage unit 302 may store the priority. Furthermore, the storage unit 302 may be set to adaptively select and use these two types of priorities.

  In addition, the storage unit 302 stores a criterion that the WebRTC server 103 monitors the real-time video and determines that there is an abnormality. This determination criterion can be set for each destination terminal 104, and may be uploaded to the storage unit 302 via the network 102 by the administrator of the destination terminal 104.

  The input device 303 is a device that receives an external input, and is, for example, a touch panel, a physical button, a mouse, a keyboard, or the like. The output device 304 is a device that outputs to the outside, and outputs information by voice (a simple sound may be used if it can be identified), display, and the like, and is, for example, a display, a speaker, or the like. The external interface 308 is for mediating between the outside and the main body, and is, for example, a USB port or the like, and is an interface for connecting to an external device.

  The clock device 306 is a device that measures time, and can measure date and time. For example, the timing device 306 is a clock including a calendar, and passes information on the current date and time to the control unit 305.

  The power supply unit 307 is not limited as long as it can supply power. For example, the power supply unit 307 receives energy supply from a rechargeable secondary battery or an AC power supply that can be obtained from a normal outlet. The power supply unit 307 supplies power to each element mounted on the WebRTC server 103 main body. The power supply unit 307 supplies power to, for example, the communication interface 301, the storage unit 302, the input device 303, the output device 304, the control unit 305, the timing device 306, and the external interface 308.

The specific hardware configuration of the WebRTC server 103 can be appropriately omitted, replaced, or added according to the embodiment. For example, the control unit 305 may include a plurality of processors. The WebRTC server 103 may be composed of a plurality of information processing devices.
[Software Configuration of WebRTC Server 103]
Next, an example of a software configuration of the WebRTC server 103 according to the present embodiment will be described with reference to FIG.
When executing a required program, the control unit 305 of the WebRTC server 103 loads the communication band securing execution program and / or the transmission completion time calculation program stored in the storage unit 302 into the RAM. Then, the control unit 305 controls each component by interpreting and executing the communication band securing execution program and / or the transmission completion time calculation program developed in the RAM by the CPU. Thereby, as shown in FIG. 4, the WebRTC server 103 according to the present embodiment includes a video acquisition unit 401, a transmission unit 402, a video monitoring unit 403, an attribute acquisition unit 404, a bandwidth calculation unit 405, a completion time calculation unit 406, A determination unit 407 and a band control unit 408 are provided.

  The video acquisition unit 401 always connects the video source and the destination terminal via the network 102 via the communication interface 301, and refers to the video data while enabling transmission of the video data from the video source to the destination terminal. Or get. The video obtaining unit 401 obtains respective video data transmitted from a plurality of video sources 101 communicating via the network 102. This video data is real-time video data or high-resolution video data (not real-time video) acquired by the video source 101 in the past, which is communicated by the WebRTC method. Also, the video acquisition unit 401 passes the received video data to the transmission unit 402, and causes the destination terminal 104 to transmit the video data.

  The video acquisition unit 401 receives data including information on the video data before the video data. Note that this data may be included in the header of the video data. The information on the video data includes, for example, identification information on whether the received video data is low-resolution video data (for example, real-time video data) or high-resolution video data. For example, when the video data is real-time video data, the video monitoring unit 403 instructs to start communication of high-resolution video data, and after the band control unit 408 controls the communication band, a request signal is sent to the video source 101. Until transmission (or until transmission of a request signal and reception of high-resolution video data), real-time video data is received from the video source 101 and is continuously transmitted to the destination terminal 104.

  Further, the video acquisition unit 401 may receive a request signal from the destination terminal 104 and the storage unit 302 may store the request content. This request is, for example, that the administrator of the destination terminal 104 requests high-resolution video data of a specific date and time and / or location taken by the specific video source 101, and includes this request from the destination terminal 104. The video acquisition unit 401 may receive the request signal. This request signal may be, for example, a request for high-resolution video data captured at a specific date and time acquired by a specific video camera 202 of the video source 101. The request signal may be transmitted any time before the time at which the request content is to be executed.

  Further, the video acquisition unit 401 also receives the request signal from the video source 101 and passes the content to the determination unit 407. The video acquisition unit 401 stores the received request signal in the storage unit 302 and notifies the storage unit 302 that the request signal has been stored. Thereafter, the determination unit 407 may obtain the content of the request signal from the storage unit 302.

  The transmission unit 402 transmits the video data that has passed through the video acquisition unit 401 from the video source 101 to the destination terminal 104 via the communication interface 301 via the network 102. For example, in the case of real-time video data, the video data is not high-resolution video data but low-resolution video data. To the destination terminal 104 via the network 102 via the. If the video data is high-resolution video data, the bandwidth control unit 408 appropriately extends the communication band between the destination terminal 104 and the video data using the extended communication band. The transmission unit 402 transmits the high-resolution video data acquired by the video acquisition unit 401 from the source 101 to the destination terminal 104. Further, the transmission unit 402 transmits request signals (also referred to as “request signals”), request data, and the like from the video monitoring unit 403 and the determination unit 407 to the video source 101 and the other WebRTC servers 103.

The video monitoring unit 403 receives the low-resolution video data (for example, real-time video data) acquired by the video acquisition unit 401, monitors the contents of the video data, and requests the video source 101 for high-resolution video data. It is determined whether or not the request is necessary, and if the request is required, the transmitting unit 402 is instructed to transmit a request signal to the video source 101.
The video monitoring unit 403 refers to, for example, a predetermined criterion, determines whether the acquired video data satisfies the criterion, and transmits a request signal if the criterion is satisfied. To the transmitting unit 402 as follows. The criterion is, for example, that a video captured by the video camera 202 installed at a specific shooting angle at a specific location includes an image including a person. In this case, when the video monitoring unit 403 finds video data that satisfies the criterion, the video monitoring unit 403 instructs the transmission unit 402 to transmit a request signal for requesting the high-resolution video data to the destination terminal 104.
Note that this criterion also depends on the arrangement of the video camera 202 in the video source 101 and / or the administrator. Further, the loudness of the sound may be included in the criterion. For example, the video camera 202 may also record audio at the same time, and the determination criterion may be satisfied when the output value (unit: dB, for example) of the audio is greater than or equal to a threshold.

  The attribute acquisition unit 404 acquires the attribute information of the video data received from the video source 101 via the communication interface 301 and passes the attribute information to the bandwidth calculation unit 405. The attribute information of the video data may be any information indicating the attribute of the video data. For example, the data amount of the video data, the destination terminal of the video data, the date and time of the video shooting, the video shooting period, and the real-time video or past There is video identification information indicating whether the video is video. Note that the video identification information is unnecessary when included in the header of the video data. In the present embodiment, the attribute information of the video data is received by the attribute acquisition unit 404 before the communication of the high-resolution video data is started, and the control unit 305 determines the attribute information of the high-resolution video data based on the attribute information. The control for securing the communication band is started.

  The band calculation unit 405 calculates a communication band required by the high-resolution video data from the attribute information acquired by the attribute acquisition unit 404, based on the data amount of the high-resolution video data corresponding to the attribute information. The communication band is usually determined by the data amount included in the attribute information and the reproduction period (corresponding to the video shooting period). If the determination unit 407 later determines that the communication band cannot be secured, the transmission period of the high-resolution video data corresponding to the reproduction period is increased so that the transmission can be completed even if the communication band is narrow. The transmission period may be adjusted. In this case, since the communication band is narrower than the required communication band, the image quality of the high-resolution video data is lower than the original image quality without changing the transmission period when reproducing the high-resolution video data in a stream, On the other hand, when downloading high-resolution video data, the image quality does not change, but the time to complete the download increases. In the case where the stream is reproduced in a state where the communication band is narrower than the required communication band, the transmission period can be lengthened to maintain the original image quality, but in this case, the reproduction speed is lower than usual.

  When downloading high-resolution video data, the download period is substantially determined by the amount of data, so that the band calculation unit 405 may determine the communication band only by the amount of data. The longer the communication band is, the shorter the download period is, but the band calculation unit 405 may calculate the communication band so as to secure the communication band on the order of ending in a specific period (for example, 5 seconds). Further, the result of the completion time calculation unit 406 is fed back to the band calculation unit 405 and recalculated by the band calculation unit 405 until the time calculated by the completion time calculation unit 406 (which may be a download period) falls within a desired period. You may.

  The completion time calculation unit 406 sends all requested high-resolution video data to the destination terminal 104 based on the communication bandwidth calculated by the bandwidth calculation unit 405 and the data amount of the high-resolution video data acquired by the attribute acquisition unit 404. The time required to transmit the high resolution video data to the destination terminal 104 is calculated based on the period and the time by referring to the time from the timer 306. After that, the completion time calculation unit 406 transmits the calculated time to the destination terminal 104 via the transmission unit 402. At the destination terminal 104, the administrator can know when transmission of the high-resolution video data is completed by a pop-up or the like. There are various methods of notifying the administrator of the transmission completion time. In addition to displaying the time on the screen, the time may be notified by voice using a speaker.

  If the attribute information includes the video shooting period and the communication band and the data amount determine that the transmission of the high-resolution video data can be completed within this video shooting period, the completion time calculation unit 406 determines The communication band may be adjusted so that transmission of high-resolution video data is completed within the shooting period. In this case, the administrator of the destination terminal 104 browses at a video speed similar to that at the time of video shooting (the same as the playback speed of high-resolution video data in the video recorder 203). When the destination terminal 104 downloads high-resolution video data, the completion time is earlier in a shorter time as the communication band is wider. Therefore, the video shooting period is not important and may not be included in the attribute information. .

  The determination unit 407 determines whether the communication band calculated by the band calculation unit 405 can be secured by adjusting the communication band secured by the WebRTC server 103. The determination unit 407 determines the priority of the destination terminal 104 that provides the communication band, the current occupation state of the communication band, the communication band required by the high-resolution video data, and the transmission completion calculated by the completion time calculation unit 406. It is determined whether or not the communication band can be secured based on the time. Note that the determination unit 407 may determine whether the communication band can be ensured in consideration of the usage state of the communication band scheduled in the future.

  If the determination unit 407 determines that the server cannot secure this communication band, for example, when playing back a stream, the data amount may be reduced to determine whether transmission is possible. In this case, the determination unit 407 determines, for example, whether or not the video shooting period of the required high-resolution video data may be reduced, and in this case, the communication bandwidth is extended while maintaining the occupation time of the extended communication bandwidth. Are repeated, and the procedure of determining whether a communication band can be secured is repeated. In the case of downloading high-resolution video data, when it is determined that the communication band cannot be secured, the download time (also referred to as “download period”) becomes longer, but it is determined in advance whether or not it is acceptable. The judgment is made with reference to the judgment criteria. Alternatively, the download time may be indicated on the destination terminal 104, and the administrator may determine whether the download time is acceptable.

  When the determination unit 407 determines that the communication band cannot be secured by the own server, the transmission unit 402 transmits request data for requesting whether to allow the other WebRTC server 103 to accommodate the communication band. To send over. The request data includes, for example, information on a required communication band and a time zone (start and end times) in which the communication band is to be used.

  Further, the determination unit 407 may receive a request signal transmitted from the destination terminal 104 and requesting browsing of the high-resolution video data, and may determine whether the browsing request can be satisfied. The determination unit 407 receives the request signal transmitted from the video source 101 and requesting the destination terminal 104 to browse the high-resolution video data (for example, when the alarm device 204 has issued an alarm). It may be determined whether or not to respond to the browsing request (in the case of an alarm, normal browsing is performed).

  When the determination unit 407 determines that the communication band can be secured, the band control unit 408 adjusts the communication band that can be handled by the WebRTC server 103 between the destination terminals 104 in consideration of the priority. Control. If it is determined that the communication band can be secured, the band control unit 408 instructs the transmission unit 402 to request the video source 101 to start transmitting high-resolution video data.

<Others>
The operation of the WebRTC server 103 will be described in detail in an operation example described later. In the present embodiment, the control unit 305 of the WebRTC server 103 may be realized by a general-purpose CPU. However, some or all of the above functions may be implemented by one or more dedicated processors. Further, regarding the configuration of the WebRTC server 103, omission, replacement, and addition may be appropriately performed according to the embodiment.

[Operation example]
Next, an operation example of the WebRTC server 103 will be mainly described with reference to FIGS. 5, 6, 7, 8, and 9.

  FIG. 5 is a sequence diagram showing an example of a series of operations between two video sources 101, one WebRTC server 103, and two destination terminals 104. Note that the processing procedure described in the sequence diagram described below is merely an example, and each processing may be changed as much as possible. Further, in the processing procedure described below, steps can be omitted, replaced, and added as appropriate according to the embodiment.

(Steps S501, S502)
In step S501, the video source 1 101 transmits real-time video data to the corresponding destination terminal 1 104 via the WebRTC server 103, and in step S502, the video source 2 101 transmits to the corresponding destination terminal 2 104 via the WebRTC server 103. To transmit real-time video data.

(Step S503)
In step S503, the WebRTC server 103 monitors the video included in the real-time video data of the video source 1 101 and the video source 2 101. The WebRTC server 103 monitors whether or not the video satisfies the criterion based on a preset criterion. In this example, it is determined that the video satisfies the determination criterion in step S503.

(Steps S504 and S505)
In step S504, it is determined that the WebRTC server 103 requests the video source 1 101 to transmit high-resolution video data.

  Then, in step S505, the WebRTC server 103 transmits a request signal to transmit high-resolution video data to the video source 1 101.

(Steps S506 and S507)
In step S506 and step S507, in response to the video source 1 101 receiving the request signal from the WebRTC server 103, the attribute information including the attribute of the high-resolution video data stored in the video source 1 101 is stored in the WebRTC server 103. Send to

(Step S508)
In step S508, the WebRTC server 103 controls the communication band handled by the WebRTC server 103 based on the attribute information received in step S507, and secures the communication band of the high-resolution video data requested in step S504. As a result, the communication band between the video source 1 101 and the destination terminal 1 104 is expanded, and the communication band between the video source 2 101 and the destination terminal 2 104 is reduced by the increased amount.

(Steps S509 and S510)
In step S509, since the communication band has been secured, it is determined to instruct the video source 1101 to start transmitting high-resolution video data.

  In step S510, the WebRTC server 103 transmits to the video source 1 101 an instruction signal for instructing the video source 1 101 to start transmitting high-resolution video data.

(Steps S511 and S512)
In step S511, upon receiving a request signal from the WebRTC server 103, the video source 1 101 uses the communication band secured in step S508 to communicate with the destination terminal 1 104 via the WebRTC server 103. The resolution video data is transmitted to the destination terminal 1104.

  In step S512, the video source 2 101 transmits low-resolution video data (for example, real-time video data) to the destination terminal 2 104 using the communication band secured in step S508. In step S511, there are a case where the destination terminal 1 104 downloads high-resolution video data and a case where stream reproduction is performed. The agreement of downloading or stream reproduction may be determined in advance at the time of contract and may be stored in the storage unit 302, or may be selected for the destination terminal 104 when high-resolution video data is transmitted. May be transmitted and the administrator may select it.

  FIG. 6 is a flowchart illustrating an example of a processing procedure for the WebRTC server 103 to secure a communication band. Note that the processing procedure described in the flowchart described below is merely an example, and each processing may be changed as much as possible. Further, in the processing procedure described below, steps can be omitted, replaced, and added as appropriate according to the embodiment.

(Start-up)
First, the WebRTC server 103 is started by an administrator or the like via the input device 212, and further receives inputs such as initial settings. The control unit 305 of the WebRTC server 103 proceeds according to the following processing procedure.

(Step S601)
In step S601, the control unit 305 operates as the video acquisition unit 401 and the transmission unit 402. The video acquisition unit 401 constantly connects the video source and the destination terminal, and enables transmission of real-time video data from the video source 101. , The transmission unit 402 transmits the real-time video data to the destination terminal 104.

(Step S602)
In step S602, the control unit 305 operates as the video monitoring unit 403 and / or the determination unit 407, and determines whether there is a request to transmit high-resolution video data to the destination terminal 104. The control unit 305 controls the operation such that the process proceeds to step S603 when it is determined that there is a transmission request, and returns to step S601 when it is not determined that there is a transmission request. When the video monitoring unit 403 determines that there is a transmission request, for example, it may be necessary to view more detailed video data by analyzing the video data acquired by the video acquisition unit 401. When the determination unit 407 determines that there is a request to transmit more detailed video data, for example, the determination unit 407 receives a transmission request for high-resolution video data from the destination terminal 104 via the communication interface 301. In this case, a request for transmission of high-resolution video data may be generated from the video source 101 (for example, the alarm device 204 may generate an alarm).

(Step S603)
In step S603, the control unit 305 operates as the attribute acquisition unit 404, the band calculation unit 405, and the completion time calculation unit 406, and the attribute acquisition unit 404 acquires the attribute information of the high-resolution video data to be transmitted from the video source 101. Then, the band calculator 405 calculates the communication band required by the high-resolution video data from the attribute information. Further, the completion time calculation unit 406 calculates a completion time at which the transmission of the high resolution video data is completed using the communication band.

(Step S604)
In step S604, the control unit 305 operates as the determination unit 407, and determines whether the communication band calculated by the determination unit 407 can be secured in a required time zone. If the determination unit 407 determines that it is possible to secure a communication band, the process proceeds to step S605; otherwise, the process proceeds to step S607.

(Step S605)
In step S605, the control unit 305 operates as the band control unit 408, and secures a communication band used by the destination terminal 104 transmitting high-resolution video data, and reduces a communication band used by the other destination terminals 104. .

(Step S606)
In step S606, the control unit 305 operates as the transmission unit 402, and transmits the high-resolution video data acquired from the video source 101 to the destination terminal 104 using the secured communication band.

(Step S607)
In step S607, the control unit 305 operates as the determination unit 407, and determines whether it is possible to reduce the amount of high-resolution video data and transmit it. In order to reduce the data amount, for example, the reproduction time of high-resolution video data may be shortened. If there is video data with a reduced resolution, it may be determined whether the video data can be transmitted. Whether the video data for reducing the data amount or the video data with the reduced resolution may be transmitted depends on, for example, a setting based on a contract between the operator of the WebRTC server 103 and the administrator of the destination terminal 104. Are stored in the storage unit 302. In addition, in addition, when the destination terminal 104 downloads high-resolution video data, for example, if the download time calculated by the completion time calculation unit 406 is smaller than a threshold, transmission is possible. Is also good.

(Step S608)
In step S608, the control unit 305 operates as the determination unit 407 and the transmission unit 402. If the determination unit 407 determines that it is impossible to reduce the amount of data to transmit, it indicates that communication is currently impossible. Is transmitted to the destination terminal 104 to which the transmission unit 402 is to transmit high-resolution video data. In some cases, the download time becomes longer than the threshold value and transmission is determined to be impossible.

(Step S609)
In step S609, the control unit 305 operates as the determination unit 407, measures the elapsed time using the timer 306, and returns to step S604 when the preset time has elapsed.

  FIG. 7 is a flowchart illustrating an example of a processing procedure for the WebRTC server 103 to calculate the time at which the video transmission is completed.

  (Activation) Activation is the same as in FIG.

(Step S701)
In step S701, the control unit 305 operates as the completion time calculation unit 406, and the attribute acquisition unit 404 determines the attribute information of the high-resolution video data transmitted from the video source 101 and the communication band calculated in step S603. , A period during which the communication of the high-resolution video data is completed is calculated.

(Step S702)
In step S702, the control unit 305 operates as the determination unit 407, and sets a transmission start time. The transmission start time is acquired from the attribute information acquired by the attribute acquisition unit 404, and the determination unit 407 sets the transmission start time. Alternatively, an instruction signal including transmission start time information may be transmitted from an administrator of the destination terminal 104 or the like, and the determination unit 407 may receive and set the transmission start time information via the communication interface 301.

(Step S703)
In step S703, the control unit 305 operates as the completion time calculation unit 406. The completion time calculation unit 406 determines the transmission completion time based on the communication completion period calculated in step S701 and the transmission start time calculated in step S702. Calculate the time.

(Step S704)
In step S704, the control unit 305 operates as the transmission unit 402. The transmission unit 402 receives the transmission completion time from the completion time calculation unit 406, and transmits the transmission completion time data including the transmission completion time to the high-resolution video. The data is transmitted to the destination terminal 104. The destination terminal 104 receives the transmission completion time data and displays the transmission completion time information on the screen. The transmission completion time is displayed, for example, in a pop-up or the like, and it is desirable that the display frame in which this time is displayed has a specification that allows easy movement within the screen.

  FIG. 8 is a sequence diagram showing an example of a series of operations between two video sources 101, two WebRTC servers 103, and two destination terminals 104. In this example, the WebRTC server 1103 alone cannot secure a communication band for communicating high-resolution video data.

(Step S801)
In step S801, the WebRTC server 1 103 can secure the required communication band of the high-resolution video data based on the attribute information of the high-resolution video data and the usage status of the communication band of the server. The process proceeds to step S508 if it is determined that it is possible to secure the communication band, and to step S802 if it is determined that the communication band cannot be secured by the own server.

(Steps S802, S803, S804)
In step S802, if the WebRTC server 1 103 determines that the server cannot secure the communication band, the Web RTC server 1 103 requests the other WebRTC server 103 to have the communication band accommodated.

  In step S803, the WebRTC server 1 103 generates request data, and transmits or distributes the request data to the other WebRTC server 103 via the transmission unit 402. In this transmission or distribution, for example, request data is transmitted by multicast or broadcast. The request data includes, for example, information on a communication band necessary for high-resolution video data and a time zone (start and end times) in which the communication band is desired to be used.

  In step S804, the WebRTC server 103 that has determined that the communication band corresponding to the information included in the request data can be accommodated transmits a response signal indicating that the accommodation is possible to the WebRTC server 1103.

(Steps S805 and S806)
In step S805, the WebRTC server 1 103 controls the communication band based on the content of the request data requested in step S803, and secures the communication band that the WebRTC server 2 103 has access to.

  At the same time with step S805, in step S806, the WebRTC server 2 103 controls the communication band based on the contents of the request data requested in step S803, and provides the communication band to the WebRTC server 1 103. As a result, the communication band between the video source 1 101 and the destination terminal 1 104 via the WebRTC server 1 103 is expanded, and the communication between the video source 2 101 and the destination terminal 2 104 via the WebRTC server 2 103 The bandwidth will be reduced by this increased amount.

(Step S807)
In step S807, since the WebRTC server 1 103 has secured the communication band, it determines to instruct the video source 1 101 to start transmitting high-resolution video data. Then, in the next step S510, the WebRTC server 1 103 transmits to the video source 1 101 an instruction signal for instructing the video source 1 101 to start transmitting high-resolution video data.

  The above procedure may be generalized, for example, as follows. In the WebRTC server 1103, when the determination unit 407 expands the communication band to the first communication band for transmitting the first video data, can the first video communication server secure the first communication band? Determine whether If the determining unit 407 determines that the first communication band cannot be secured, the transmitting unit 402 sends an answer as to whether the second video communication server can accommodate the first communication band. Transmits request data to the WebRTC server 2 103 to request. Then, the WebRTC server 2 103 receives the request data, and the determining unit 407 determines whether it is possible to accommodate the first communication band. When the determination unit 407 determines that the first communication band can be accommodated, it transmits an answer signal indicating that the first communication band can be accommodated to the WebRTC server 1 103, and the band control unit 408 The first communication band is released. Thereafter, in the WebRTC server 1103, the response signal is received, and the band control unit 408 secures the first communication band.

  In addition to the example shown in FIG. 8, when the priority is assigned to each WebRTC server 103 and the communication band of the video data to the first destination terminal is expanded, the WebRTC server 1 providing this communication band Even if an instruction is given to reduce the communication band used by the WebRTC server 2 103 having a lower priority than the priority of 103, and the reduced communication band is assigned to the first destination terminal via the WebRTC server 1 103 Good. Further, the WebRTC server 1 103 transmits an instruction signal to the WebRTC server 2 103 having a low priority to reduce the communication band, and sends a response signal indicating that the WebRTC server 2 103 can reduce the communication band to the WebRTC server 2 103. When the first communication terminal 103 receives the communication band, the reduced communication band may be allocated to the first destination terminal via the WebRTC server 103.

  For example, in the WebRTC server 1 103, when the determination unit 407 expands the communication band to the first communication band for transmitting the first video data, the first video communication server can secure the first communication band. Is determined. When the determination unit 407 determines that the first communication band cannot be secured, the transmission unit 402 transmits request data including the accommodation of the first communication band and the priority of the WebRTC server 1103, It transmits to WebRTC server 2 103. Then, in the WebRTC server 2 103, the determination unit 407 receives the request data via the communication interface 301, and determines whether the priority of the WebRTC server 1 103 is higher than the priority of the WebRTC server 2 103. When the bandwidth control unit 408 determines that the priority of the WebRTC server 1 103 is higher than the priority of the WebRTC server 2 103, the bandwidth control unit 408 transmits to the WebRTC server 1 103 an answer signal indicating that the first communication band can be accommodated. Then, the first communication band is released. After that, in the WebRTC server 1 103, the band control unit 408 can receive the answer signal via the communication interface 301 and secure the first communication band.

  FIG. 9 shows a case in which the WebRTC server 1 103 cannot secure a communication band for communicating high-resolution video data by itself, and requests the other WebRTC server 103 to provide a communication band. It is a flowchart of FIG.

  (Activation) Activation is the same as in FIG.

(Step S901)
In step S901, the control unit 305 operates as the determination unit 407. If the WebRTC server 1103 determines that the server cannot secure the communication band, the control unit 305 determines whether the communication band can be accommodated. Request to another WebRTC server 103. Then, in step S901, the WebRTC server 1 103 generates request data, and transmits or distributes the request data to the other WebRTC server 103 via the transmission unit 402.

(Step S902)
In step S902, the control unit 305 operates as the determination unit 407, and the determination unit 407 determines whether an answer signal of the request data transmitted or distributed in step S901 has been received. If an answer signal has been received, the WebRTC server 103 that has transmitted the signal determines that the communication band can be accommodated, and proceeds to step S903. If no answer signal has been received, the communication band can be accommodated. It is determined that there is no WebRTC server 103, and the process proceeds to step S607.

(Step S903)
In step S903, the control unit 305 operates as the determination unit 407 and the band control unit 408, and based on the answer signal, the band control unit 408 secures a communication band for high-resolution video data. As a result, the WebRTC server 103 that has provided the communication band reduces the communication band handled during the provision of the communication band (the transmission period of the high-resolution video data).
When step S903 ends, the process proceeds to step S606.

  As described above, according to the present embodiment, the video communication server (WebRTC server 103) that constantly connects a plurality of video sources and the destination terminal via the network has priority over the communication band assigned to the destination terminal. If it becomes necessary to communicate high-resolution video data to a destination terminal having a higher priority, the communication band used by a destination terminal having a lower priority is reduced to thereby increase the priority. It is possible to expand the communication band used by the destination terminal. Also, by acquiring the attribute information of the high-resolution video data, the communication band and period required for the communication of the high-resolution video data can be calculated. It is possible to know in advance whether the download of the high-resolution video data has been completed (if the video is being reproduced in the stream, whether the reproduction of the high-resolution video data has ended).

The server of the present embodiment can be realized by a computer and a program, and the program can be recorded on a recording medium (or a storage medium) or can be provided through a network.
Further, each of the above devices and their device portions can be implemented with either a hardware configuration or a combination configuration of hardware resources and software. The software of the combination configuration is installed in a computer in advance from a network or a computer-readable recording medium (or storage medium), and is executed by a processor of the computer, so that the operation (or function) of each device is transferred to the computer. A program for realizing is used.

  Further, “and / or” means any one or more of the items connected and listed by “and / or”. To give a specific example, “x and / or y” means any element of a set {(x), (y), (x, y)} composed of three elements. As another specific example, “x, y, and / or z” is a set of seven elements ｛(x), (y), (z), (x, y), (x, z ), (Y, z), (x, y, z)}.

  Although several embodiments of the present invention have been described, these embodiments are provided by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in other various forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and equivalents thereof.

  101: video source, 102: network, 103: WebRTC server, 104: destination terminal, 201: relay device, 202: video camera, 203: video recorder, 204: alarm device, 205: button, 206: pedal, 212: input Device, 251, client terminal, 252, mobile terminal, 301, communication interface, 302, storage unit, 303, input device, 304, output device, 305, control unit, 306, clock unit, 307, power supply unit, 308, external Interface 401, video acquisition unit, 402 transmission unit, 403 video monitoring unit, 404 attribute acquisition unit, 405 bandwidth calculation unit, 406 completion time calculation unit, 407 determination unit, 408 bandwidth control unit.

Claims (15)

A connection unit that constantly connects a plurality of video sources and a plurality of destination terminals via a network and enables transmission of a plurality of video data from the plurality of video sources to the plurality of destination terminals,
For each of the destination terminals corresponding to each of the plurality of video data, a higher communication bandwidth can be used, and a bandwidth control for controlling a communication band for each destination terminal according to a priority set in association with the destination terminal Department and
A transmitting unit that transmits the plurality of video data to a corresponding destination terminal according to a communication band for each destination terminal,
A video communication server comprising:   The bandwidth control unit reduces a communication bandwidth used by a second destination terminal having a lower priority than the priority of the first destination terminal when expanding a communication band of video data to the first destination terminal. The video communication server according to claim 1, wherein the reduced communication band is allocated to the first destination terminal. The transmission unit transmits request data for requesting the other video communication server to answer whether or not another video communication server can accommodate a communication band having a designated size,
2. The video communication server according to claim 1, wherein the bandwidth control unit receives a response signal that can be provided from the other video communication server when the bandwidth can be accommodated, and controls the communication bandwidth. An acquisition unit that acquires attribute data including attribute information on the video data via the network,
A first calculation unit that calculates a first communication band necessary for transmitting first video data to a first destination terminal corresponding to the video data based on the attribute data;
A determining unit that determines whether the priority of the first destination terminal allows the first communication band,
When the determination unit determines that the first communication band is allowed, the band control unit secures the first communication band for the first destination terminal, and the video data of another destination terminal is transmitted to the first communication band. The video communication server according to any one of claims 1 to 3, wherein the video communication server allocates the bandwidth other than the bandwidth. A second calculating unit that calculates a transmission completion time at which the transmission of the first video data is completed to the first destination terminal according to the attribute data of the first video data and the first communication band;
The video communication server according to claim 4, wherein the transmission unit transmits completion time data including the transmission completion time to the destination terminal. The connection unit enables transmission of the video data in real time,
When the determination unit determines that the first communication band is permitted, the connection unit disables transmission of the video data, and connects at least one of the plurality of video sources to a destination terminal. Transmitting the first video data,
The video communication server according to claim 4, wherein the transmission unit transmits the first video data to the first destination terminal using the first communication band.   The video communication server according to claim 4, wherein the first video data is video data that has already been recorded.   The acquisition unit may include, as the attribute information, at least one of a data amount of the video data, destination terminal information of the video data, a video playback time, and video identification information indicating whether the video is a real-time video or a past video. The video communication server according to any one of claims 4 to 7, including the above. A connection unit that constantly connects a plurality of video sources and a plurality of destination terminals via a network and enables transmission of a plurality of video data from the plurality of video sources to the plurality of destination terminals,
A higher bandwidth allows a wider communication band to be used, and controls a communication band for each video communication server according to a priority set in association with the video communication server;
A transmission unit that transmits the plurality of video data to the corresponding destination terminal according to a communication band for each destination terminal corresponding to each of the plurality of video data,
A video communication server comprising:   The bandwidth control unit is configured to, when expanding a first communication band of video data to a first destination terminal, provide a second video communication server having a lower priority than a priority of a first video communication server providing the first communication band. The video communication server according to claim 9, wherein the video communication server is instructed to reduce a communication band used by the video communication server, and the reduced communication band is allocated to the first destination terminal via the first video communication server. .   The video communication server according to claim 1, wherein the video data is video data conforming to a WebRTC method. In a system including a first video communication server and a second video communication server for constantly connecting a plurality of video sources each outputting video data and a plurality of destination terminals via a network,
The first video communication server,
A first determining unit that determines whether the first video communication server can secure the first communication band when the communication band is extended to the first communication band for transmitting video data;
If the first determination unit determines that the first communication band cannot be secured, the second video communication server sends an answer as to whether the first communication band can be accommodated. A transmission unit that transmits request data for requesting the second video communication server,
The second video communication server,
A second determination unit that receives the request data and determines whether it is possible to accommodate the first communication band;
When the second determination unit determines that the first communication band can be accommodated, the response unit transmits an answer signal indicating that the first communication band can be accommodated to the first video communication server. A band control unit that releases the first communication band;
The first video communication server,
The system further comprising a band control unit that receives the answer signal and secures the first communication band. A first video communication server and a second video communication server, which are always connected to a plurality of video sources each outputting video data and a plurality of destination terminals via a network, and are assigned higher priority so that a wider communication band can be used. In a system including a video communication server,
The first video communication server,
A first determining unit that determines whether the first video communication server can secure the first communication band when the communication band is extended to the first communication band for transmitting video data;
When the first determination unit determines that the first communication band cannot be secured, the request data including the flexibility of the first communication band and the priority of the first video communication server is transmitted to the first communication unit. (2) a transmission unit for transmitting to the video communication server;
The second video communication server,
A second determination unit that receives the request data and determines whether a priority of the first video communication server is higher than a priority of the second video communication server;
When it is determined that the priority of the first video communication server is higher than the priority of the second video communication server, an answer signal indicating that the first communication band can be accommodated is sent to the first video communication server. A band control unit that transmits and releases the first communication band;
The first video communication server,
The system further comprising a band control unit that receives the answer signal and secures the first communication band. Always connect between a plurality of video sources and a plurality of destination terminals via a network to enable transmission of a plurality of video data from the plurality of video sources to the plurality of destination terminals,
For each destination terminal corresponding to each of the plurality of video data, a higher communication band can be used, and a communication band for each destination terminal is controlled in accordance with a priority set in association with the destination terminal,
Transmitting the plurality of video data to a corresponding destination terminal according to a communication band for each destination terminal;
A video communication method comprising:   A program for causing a computer to function as each unit included in the video communication server according to any one of claims 1 to 11.