WO2019159893A1

WO2019159893A1 - Data distribution device, system, method, and recording medium

Info

Publication number: WO2019159893A1
Application number: PCT/JP2019/004852
Authority: WO
Inventors: 浩一二瓶
Original assignee: 日本電気株式会社
Priority date: 2018-02-15
Filing date: 2019-02-12
Publication date: 2019-08-22

Abstract

In order to enable a greater possibility that the time required for data distribution will satisfy a permission condition, the present invention is configured to: distribute data to a data reception device; receive a message in response to the data from the data reception device; and lower a bit rate during the distribution of the data, when a round-trip delay time from the distribution of the data to the reception of the response message exceeds a prescribed value based on the permission condition regarding the time required for the distribution of the data.

Description

Data distribution apparatus, system, method and recording medium

The present invention relates to a data distribution apparatus, system, method, and recording medium for distributing data.

Robots such as UAV (Unmanned vehicle) and UGV (unmanned vehicle) are attracting attention, and there is a need for an operator to remotely control the robot while viewing the video. In order for the operator to operate the robot as intended, it is necessary to deliver high-quality video with low delay. For example, 3GPP (Third Generation Partnership Project) TS 22.281 defines the video delay requirement for UAV remote control as less than 500 ms.

Wireless networks are generally used for video distribution from robots. Also, when the distance between the operator and the robot is long, video distribution may be performed via the Internet or the like. In these networks, the communication speed fluctuates due to changes in radio field intensity, interference, traffic from other terminals, and the like.

There are methods described in Patent Document 1 to Patent Document 5 as a method for performing low-latency video distribution in a network in which the communication speed varies. In these methods, the delay is reduced by lowering the transmission rate when a deterioration in communication quality is detected.

For example, in the method described in Patent Document 1, when the communication speed (network link rate) decreases, data is transmitted at a bit rate (recovery bit rate) lower than the communication speed after the decrease. In the method described in Patent Literature 2, when it is determined that the delay time exceeds a predetermined upper limit value, the maximum transmission rate is determined. Further, in the method described in Patent Document 3, when the delay amount is larger than a threshold value that only the data amount less than the maximum transmission amount is transmitted, the transmission rate is lowered. Further, in the method described in Patent Document 4, the coding coefficient is lowered when a statistical value such as a transfer delay greatly exceeds an allowable reference value defined in advance. In the method described in Patent Document 5, when it is determined that the delay time has increased, the transmission rate is lowered.

JP-T-2017-530484 JP 2013-098759 A JP 2012-010097 A Special table 2011-529306 gazette JP 2005-136548 A Japanese Unexamined Patent Publication No. 2017-192057

However, in any of the methods described in Patent Document 1 to Patent Document 5, allowable conditions regarding the time required for data distribution, for example, video delay requirements defined in 3GPP TS 22.281, and conditions for controlling the transmission rate, Is not related, there is a possibility that the allowable condition cannot be satisfied.

An object of the present invention is to provide a data distribution apparatus, system, method, and recording medium that can improve the possibility that the time required for data distribution satisfies the allowable condition.

In order to solve the above-described problem, in one embodiment of the present invention, a data distribution apparatus includes a data distribution unit that distributes data to a data reception apparatus, and a response reception that receives a response message for the data from the data reception apparatus And when the round-trip delay time from the delivery of the data to the reception of the response message exceeds a prescribed value based on an allowable condition related to the time taken for the delivery of the data. A bit rate determining means for instructing the data distribution means to lower the bit rate.

In another embodiment of the present invention, a data distribution method distributes data to a data receiving device, receives a response message to the data from the data receiving device, and receives the response message from the distribution of the response message. When the round-trip delay time until reception exceeds a prescribed value based on an allowable condition regarding the time required for the distribution of the data, the bit rate at the time of the distribution of the data is lowered.

In another embodiment of the present invention, a data distribution program stored in a computer-readable recording medium includes a data distribution function for distributing data to a data receiving device to a computer, and a response message for the data. When the response reception function received from the receiving device and the round-trip delay time from the delivery of the data to the reception of the response message exceed a prescribed value based on an allowable condition related to the time taken for the delivery of the data, And a bit rate determining function for instructing a data distribution function to lower the bit rate during the distribution of the data.

The data distribution apparatus, system, method, and recording medium of the present invention can improve the possibility that the time required for data distribution satisfies the allowable condition.

It is a figure which shows the structural example of the data delivery apparatus of 1st embodiment of this invention. It is a figure which shows the operation example of the data delivery apparatus of 1st embodiment of this invention. It is a figure which shows the structural example of the data delivery system of 2nd embodiment of this invention. It is a figure which shows the structural example of the data receiver of 2nd to 5th embodiment of this invention. It is a figure which shows the structural example of the data delivery apparatus of 2nd-5th embodiment of this invention. It is a figure which shows the operation example of the data delivery system of 2nd to 5th embodiment of this invention. It is a figure which shows the operation example of the data delivery apparatus of 2nd-5th embodiment of this invention. It is a figure which shows the operation example of the data delivery apparatus of 2nd-5th embodiment of this invention. It is a figure which shows the example of the relationship between RTT and communication quality. It is a figure which shows the example of the relationship between the regulation value Dth of 3rd embodiment of this invention, and permissible conditions. It is a figure which shows the example of the range of the regulation value Dth of 3rd embodiment of this invention. It is a figure which shows the example of the time stamp of 3rd embodiment of this invention. It is a figure which shows the example of the time stamp of 3rd embodiment of this invention. It is a figure which shows the example of the regulation value Dth of 4th embodiment of this invention. It is a figure which shows the example of the range of the regulation value Dth of 4th embodiment of this invention. It is a figure which shows the hardware structural example of each embodiment of this invention.

[First embodiment]
A first embodiment of the present invention will be described.

FIG. 1 shows a configuration example of the data distribution apparatus 10 of the present embodiment. The data distribution apparatus 10 according to the present embodiment includes a data distribution unit 11, a response reception unit 12, and a bit rate determination unit 13.

The data distribution unit 11 distributes data to the data receiving device. The response receiving unit 12 receives a response message for data from the data receiving device. The bit rate determination unit 13 determines the bit rate for data distribution when the round-trip delay time from data distribution to response message reception exceeds a specified value based on the allowable condition regarding the time required for data distribution. The reduction is instructed to the data distribution unit 11.

By configuring the data distribution apparatus 10 in this way, the data distribution apparatus 10 can be configured to provide a bit rate for data distribution when the round-trip delay time exceeds a specified value based on an allowable condition related to the time required for data distribution. Lower. Thereby, since the data distribution apparatus 10 uses the specified value based on the allowable condition, it is possible to control the bit rate so that the time required for data distribution satisfies the allowable condition. In addition, since the data distribution apparatus 10 uses the round-trip delay time of data, it is possible to detect a deterioration in communication quality more quickly than using a statistical value such as a communication speed and lower the bit rate. Therefore, it is possible to improve the possibility that the time required for data distribution satisfies the allowable condition.

Next, FIG. 2 shows an example of the operation of the data distribution apparatus 10 of the present embodiment.

The bit rate determination unit 13 determines the bit rate at the time of data distribution when the round-trip delay time from the data distribution to the reception of the response message exceeds a specified value based on the allowable condition regarding the time required for data distribution. Lowered (step S101).

By operating in this way, the data distribution apparatus 10 reduces the bit rate at the time of data distribution when the round trip delay time exceeds the specified value based on the allowable condition regarding the time required for data distribution. Therefore, it is possible to improve the possibility that the time required for data distribution satisfies the allowable condition.

As described above, in the first embodiment of the present invention, the data distribution device 10 performs the data distribution when the round trip delay time exceeds the specified value based on the allowable condition regarding the time required for the data distribution. Lower the bit rate. Thereby, since the data distribution apparatus 10 uses the specified value based on the allowable condition, it is possible to control the bit rate so that the time required for data distribution satisfies the allowable condition. In addition, since the data distribution apparatus 10 uses the round-trip delay time of data, it is possible to detect a deterioration in communication quality more quickly than using a statistical value such as a communication speed and lower the bit rate. Therefore, it is possible to improve the possibility that the time required for data distribution satisfies the allowable condition.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. In the present embodiment, the data distribution device 20 will be described more specifically.

First, FIG. 3 shows a configuration example of the data distribution system of this embodiment. The data distribution system according to this embodiment includes a data distribution device 20 and a data reception device 40. The data distribution device 20 and the data reception device 40 are connected via a network 50. One or more data receiving devices 40 may be connected to one data distribution device 20.

Next, FIG. 4 shows a configuration example of the data receiving device 40 of the present embodiment. The data receiving device 40 includes a communication unit 41, a decoding unit 42, a data output unit 43, and a response generation unit 44.

The communication unit 41 receives data from the data distribution device 20 and transmits a response message to the received data to the data distribution device 20.

The decryption unit 42 decrypts the data input from the communication unit 41.

The data output unit 43 passes the data decoded by the decoding unit 42 to the output device. The output device is, for example, a display, a speaker, a storage device, or the like.

The response generation unit 44 generates a response message for the data received from the data distribution device 20. The response message may include an identifier for identifying which data is a response message, and feedback information such as a reception rate of the data.

Next, a configuration example of the data distribution apparatus 20 according to the present embodiment will be described with reference to FIG. The data distribution device 20 of this embodiment includes a data input unit 21, an encoding unit 22, a communication unit 23, a communication quality measurement unit 24, and a bit rate determination unit 25. A part of the data input unit 21, the encoding unit 22, and the communication unit 23 in FIG. 5 corresponds to the data distribution unit 11 in FIG. 5 and the communication quality measuring unit 24 correspond to the response receiving unit 12 in FIG. Further, the bit rate determining unit 25 in FIG. 5 corresponds to the bit rate determining unit 13 in FIG.

The data input unit 21 receives data from the input device. The input device is, for example, a camera, a microphone, a sensor, or the like. When the input device is a camera, data input to the data input unit 21 by the input device is video data. In this case, the input device can input data to the data input unit 21 in units of video frames, for example. When the input device is a microphone, the data input to the data input unit 21 by the input device is audio data. In this case, the input device can input data to the data input unit 21 in units of audio data for a certain time (for example, 20 ms), for example.

The encoding unit 22 encodes the data received from the data input unit 21 so that the bit rate is instructed by the bit rate determination unit 25. For example, if the data input from the data input unit 21 is video data, the encoding unit 22 H.264 and H.264. Data is encoded using a video encoding method such as H.265 (HEVC (High Efficiency Video Coding)) and Motion JPEG (Joint Photographic Experts Group). When the input data is audio data, the encoding unit 22 encodes the data using an audio encoding method such as AAC (Advanced Audio Coding) or AMR (Adaptive Multi-Rate).

The communication unit 23 distributes the data encoded by the encoding unit 22 to the data receiving device 40. Also, a response message from the data receiving device 40 is received.

The communication quality measuring unit 24 measures the communication quality between the data distribution device 20 and the data receiving device 40 based on the response message from the data receiving device 40. In the present embodiment, the communication quality measuring unit 24 measures a round trip delay time from data distribution to response message reception.

The bit rate determining unit 25 determines a bit rate for distributing data to the data receiving device 40 based on the measurement result of the communication quality measuring unit 24 (in this embodiment, round-trip delay time), and sends the data to the encoding unit 22. Instruct. More specifically, the bit rate determining unit 25 encodes a decrease in the bit rate at the time of data distribution when the round trip delay time exceeds a prescribed value based on an allowable condition related to the time required for data distribution. 22 is instructed.

By configuring the data distribution apparatus 20 in this manner, the data distribution apparatus 20 can be used to distribute a bit rate when data is distributed when the round-trip delay time exceeds a specified value based on an allowable condition related to the time required for data distribution. Lower. Thereby, since the data distribution apparatus 20 uses the prescribed value based on the allowable condition, it is possible to control the bit rate so that the time required for data distribution satisfies the allowable condition. In addition, since the data distribution device 20 uses the round-trip delay time of data, it is possible to detect a deterioration in communication quality more quickly than using a statistical value such as a communication speed and lower the bit rate. Therefore, it is possible to improve the possibility that the time required for data distribution satisfies the allowable condition.

Next, an operation example of the data distribution system of this embodiment will be described with reference to FIG.

The data distribution device 20 distributes data to the data reception device 40 (step S201). When receiving the data (step S202), the data receiving device 40 transmits a response message to the received data to the data distribution device 20 (step S203). It is desirable that the data receiving device 40 transmits the response message as quickly as possible. The data distribution device 20 and the data reception device 40 repeat the operations from step S201 to step S204.

Next, an operation example of the data distribution apparatus 20 according to the present embodiment will be described with reference to FIGS.

When the data input unit 21 inputs data to the encoding unit 22 (step S301 in FIG. 7), the bit rate determination unit 25 determines whether or not the bit rate needs to be changed. If a change is necessary (YES in step S302), the bit rate determination unit 25 instructs the encoding unit 22 to change the bit rate (step S303). The encoding unit 22 encodes data at the bit rate specified by the bit rate determining unit 25 (step S304), and the communication unit 23 distributes the encoded data to the data receiving device 40 (step S305).

FIG. 8 is a specific example of step S302 in FIG. First, in the case of a periodic bit rate change timing (YES in step S306), the bit rate determining unit 25 instructs the encoding unit 22 to change the bit rate (step S303). Note that the periodic bit rate change timing is a predetermined cycle. If it is not a periodic bit rate change timing (NO in step S306), the bit rate determining unit 25 further determines whether or not the communication quality is deteriorated. When the communication quality is deteriorated (YES in step S307), the bit rate determining unit 25 instructs the encoding unit 22 to change the bit rate (step S303). On the other hand, if it has not deteriorated (NO in step S307), the bit rate determination unit 25 does not give an instruction to change the bit rate.

The determination of the presence or absence of communication quality deterioration in step S307 is performed by the bit rate determination unit 25 based on the response message transmitted from the data reception device 40. For example, the bit rate determination unit 25 determines whether communication quality has deteriorated based on a round-trip delay time (hereinafter referred to as RTT (round-trip time)) from when the data distribution device 20 distributes data to when a response message is received. Can be determined.

FIG. 9 is a diagram showing the difference in RTT between when the communication quality is good and when it is bad. A solid line arrow represents data, and a broken line arrow represents a response message. The communication device 60 is a communication device that constitutes the network 50. When the communication quality is good (the upper part of FIG. 9), the communication device 60 transmits the data to the data receiving device 40 immediately after receiving the data from the data distribution device 20. On the other hand, when the communication quality between the communication device 60 and the data reception device 40 is poor or when a large amount of data is transmitted from another device (lower part of FIG. 9), the communication device 60 transmits the data after receiving it. There is a waiting time in between. Therefore, the RTT (RTT2) when the communication quality is poor is longer than the case where the communication quality is good (RTT1). From this, when RTT becomes long, the bit rate determination part 25 can determine with communication quality having deteriorated.

In step S303 in FIG. 7, the bit rate determination unit 25 uses the method described in Patent Document 6 in the case of periodic bit rate change timing (YES in step S306 in FIG. 8). The bit rate can be determined.

When the communication quality deterioration is detected (YES in step S307 of FIG. 8), the bit rate determination unit 25 multiplies the current bit rate by a (0 <a <1) after the change. It may be set to a value. Alternatively, the bit rate determining unit 25 multiplies the bit rate after the change by b (0 <b <1) the reception rate included in the last received response message when the reception rate is included in the response message. It may be set to a value. Note that the bit rate determination unit 25 may use a value obtained by smoothing past reception rate information instead of using the reception rate included in the last received response message. In these methods, the bit rate determination unit 25 instructs the encoding unit 22 to decrease the bit rate when the communication quality deterioration is detected.

By operating in this way, the data distribution device 20 reduces the bit rate at the time of data distribution when the round trip delay time exceeds the prescribed value based on the permissible conditions regarding the time required for data distribution. Therefore, it is possible to improve the possibility that the time required for data distribution satisfies the allowable condition.

As described above, in the second embodiment of the present invention, the data distribution device 20 performs the data distribution when the round trip delay time exceeds the specified value based on the allowable condition regarding the time required for the data distribution. Lower the bit rate. Thereby, since the data distribution apparatus 20 uses the prescribed value based on the allowable condition, it is possible to control the bit rate so that the time required for data distribution satisfies the allowable condition. In addition, since the data distribution device 20 uses the round-trip delay time of data, it is possible to detect a deterioration in communication quality more quickly than using a statistical value such as a communication speed and lower the bit rate. Therefore, it is possible to improve the possibility that the time required for data distribution satisfies the allowable condition.

[Third embodiment]
Next, a third embodiment of the present invention will be described. In the present embodiment, a case where the data distribution device 20 is applied to video distribution for remote control will be described.

First, a configuration example of the data distribution system of this embodiment will be described. The configuration example of the data distribution system according to this embodiment is the same as the configuration example (FIG. 3) of the data distribution system according to the second embodiment.

The data distribution device 20 and the data reception device 40 are terminal devices such as a PC (Personal Computer) and a smartphone, for example. The network 50 is, for example, a wireless LAN (Local Area Network). In the present embodiment, it is assumed that the data distribution device 20 and the data reception device 40 can directly communicate via the network 50.

Next, a configuration example of the data receiving device 40 of this embodiment will be described. The configuration example of the data reception device 40 of the present embodiment is the same as the configuration example (FIG. 4) of the data reception device 40 of the second embodiment.

The communication unit 41 of the data receiving device 40 is configured by a combination of software and communication modules that operate on the data receiving device 40. The decoding unit 42 is software operating on the data receiving device 40, or a circuit on a GPU (Graphics Processing Unit) or SoC (System-on-a-Chip). The data output unit 43 is a display on the data receiving device 40. The response generation unit 44 is software of the data reception device 40.

Next, a configuration example of the data distribution device 20 of the present embodiment will be described. The configuration example of the data distribution device 20 of the present embodiment is the same as the configuration example (FIG. 5) of the data distribution device 20 of the second embodiment.

The data input unit 21 of the data distribution apparatus 20 is a camera built in the data distribution apparatus 20 or connected to the data distribution apparatus 20 via an interface such as USB (Universal Serial Serial Bus). The encoding unit 22 is software operating on the data distribution device 20 or a circuit on a GPU or SoC. The communication unit 23 is configured by a combination of software operating on the data distribution apparatus 20 and a communication module. The communication quality measurement unit 24 and the bit rate determination unit 25 are software that operates on the data distribution device 20.

Next, data transmission / reception units in the data distribution device 20 and the data reception device 40 will be described.

The data in this embodiment is a video stream, and the data distribution device 20 distributes the video stream to the data reception device 40 in units of video frames. That is, the data distribution apparatus 20 distributes video data constituting one frame, and the data reception apparatus 40 transmits an acknowledgment (ack) message notifying that one frame has been received.

The response generation unit 44 of the data receiving apparatus 40 can store the identifier (time stamp or the like) of the target video frame and the reception rate of the video frame in the ack message.

The response generation unit 44 can calculate the reception rate by Equation 1 when the video frame is composed of a plurality of packets.

Reception rate = Video frame size / (Last packet reception time-First packet reception time) (Equation 1)

In general, a video is composed of several frames to several tens of frames per second. Therefore, the frame transmission interval is several tens of milliseconds to several hundreds of milliseconds.

The above method is merely an example, and the method for calculating the data transmission unit and the reception rate is not limited thereto. For example, the communication unit 23 of the data distribution device 20 may use a slice constituting a part of a frame or a group of a plurality of frames as a transmission unit. In addition, the communication unit 41 of the data receiving device 40 may transmit the response message for each packet when the data to be transmitted at a time is composed of a plurality of packets. When the data reception device 40 transmits a response message for each packet, the data distribution device 20 can detect a packet loss, so that it is possible to improve image quality (reduction of block noise, etc.) by retransmission.

Next, the bit rate determination unit 25 of the data distribution device 20 of this embodiment will be described.

The bit rate determination unit 25 can determine the deterioration of the communication quality based on the RTT. The bit rate determination unit 25 can calculate the RTT based on the time stamp difference between the video frame to be distributed next and the video frame that has been ack received. When the ack is received up to the i-th frame and the j-th frame is delivered next, the bit rate determination unit 25 can calculate the RTT using Equation 2. TS (x) is the time stamp of the xth video frame.

Then, the bit rate determining unit 25 determines that the communication quality is deteriorated when the RTT exceeds the specified value Dth, that is, when the RTT satisfies Expression 3, and encodes the decrease in the bit rate during data distribution. The control unit 22 is instructed.

Here, the specified value Dth is a specified value based on an allowable condition regarding the time required for data distribution. In the present embodiment, the bit rate determination unit 25 calculates the specified value Dth based on the allowable conditions.

FIG. 10 is a diagram showing the relationship between the specified value Dth and the allowable conditions.

In order for the video frame to satisfy the permissible condition, the time from when the data distribution device 20 starts the process regarding the distribution of the video frame until the data reception device 40 completes the process regarding the reception of the video frame needs to satisfy the permissible condition. There is. Therefore, the communication delay requirement Dreq to be satisfied from the time when the data distribution device 20 distributes the video frame to the time when the data reception device 40 receives the video frame is determined by the processing of the data distribution device 20 and the data reception device 40 from the allowable condition. The value is obtained by subtracting time (Formula 4).

In addition, in order for the data distribution device 20 to receive ack after the data reception device 40 transmits ack, the one-way propagation delay time Dow (time required for signal transmission) from the data reception device 40 to the data distribution device 20 It takes.

Therefore, in order for the time from the start of the video frame distribution process of the data distribution apparatus 20 to the completion of the reception process of the video frame of the data reception apparatus 40 to satisfy the permissible condition, the RTT includes the communication delay requirement Dreq and the one-way propagation delay time Dow. Must be less than the sum of For this reason, the prescribed value Dth for determining deterioration in communication quality needs to satisfy Equation 5.

Therefore, the bit rate determining unit 25 selects the specified value Dth from the range shown in FIG. For example, the bit rate determining unit 25 calculates the specified value Dth using Equation 6. The coefficient c is a value (0 ≦ c <1) determined in advance by the operator.

Note that when calculating the communication delay requirement Dreq using Equation 4, the bit rate determination unit 25 can use a value predetermined by the operator for the processing time of the data distribution device 20 and the data reception device 40. . Alternatively, the bit rate determination unit 25 can calculate the processing time based on an equation set by an operator or device developer. For example, it is possible for the bit rate determination unit 25 to calculate the processing time of the data distribution device 20 using an expression in which the processing time varies depending on the video resolution, frame rate, and the like.

Also, the bit rate determining unit 25 transmits a probe packet such as ICMP (Internet Control Message Protocol) Echo to the data receiving device 40 before starting the video distribution, for example. A value obtained by dividing the round trip delay time of the probe packet by 2 may be used as the one-way propagation delay time Dow.

In addition, when time synchronization between devices is possible with high accuracy by GPS (Global Positioning System) or the like, the data receiving device 40 calculates the one-way propagation delay time Dow by Equation 7 and puts it in the response message to the data distribution device. Feedback to 20 is also possible. It is assumed that the transmission time of the data distribution device 20 is stored in the transmission packet.

Dow = Reception time at the data receiving device 40−Transmission time at the data distribution device 20 (Expression 7)

Next, a specific example of calculating the specified value Dth will be described.

As described above, 3GPP TS 22.281 stipulates that the video delay requirement (allowable condition) for UAV remote control is less than 500 ms. Assuming that the processing time of the data distribution device 20 and the data reception device 40 is 100 ms, the communication delay requirement Dreq is calculated as 300 ms by Equation 4.

In this embodiment, since the data distribution device 20 and the data reception device 40 can directly communicate with each other, assuming that Dow≈0, Dreq + Dow = 300 ms. Then, the bit rate determining unit 25 can calculate the specified value Dth using Equation 6.

However, when the specified value Dth is close to Dreq + Dow, the bit rate determination unit 25 does not determine that the communication quality is deteriorated in a state where the time required for data distribution satisfies the allowable condition. For this reason, when the communication speed suddenly decreases, there is a possibility that the time required for data distribution does not satisfy the permissible condition because the process for reducing the bit rate is not in time. Therefore, it is desirable to set the specified value Dth to a small value (for example, 50 ms). If the specified value Dth is small, the bit rate is lowered in a state where the time required for data distribution is sufficient for the permissible condition, so that the possibility that the time required for data distribution does not satisfy the permissible condition is reduced.

Next, a specific example of determination of communication quality deterioration will be described. It is assumed that the specified value Dth is 50 ms.

FIG. 12 is a diagram illustrating an example of the time stamp of the past frame and the presence / absence of ack reception at the timing (j = 11) when the eleventh frame is delivered. In the case of this example, since the data distribution apparatus 20 has received ack up to the fifth frame (i = 5), it is calculated as RTT = 240 ms (TS (11) −TS (5)) using Equation 2. To do. Since the RTT satisfies Expression 3, the bit rate determining unit 25 determines that the communication quality is deteriorated.

FIG. 13 is a diagram illustrating an example in which the eleventh frame is distributed as in FIG. 12, but the data distribution apparatus 20 has received ack up to the tenth frame. In this case, RTT = 40 ms (TS (11) −TS (10)), and the RTT does not satisfy Equation 3, so the bit rate determining unit 25 does not determine that the communication quality has deteriorated.

In the above description, the bit rate determination unit 25 immediately determines that the communication quality has deteriorated when the RTT satisfies Expression 3, but satisfies the Expression 3 continuously for a plurality of frames (for example, two frames). May be determined as communication quality deterioration. By doing so, the bit rate does not decrease when the communication quality deteriorates for a very short time, so that high-quality video distribution is possible.

Also, the bit rate determining unit 25 determines the bit rate instructed to the encoding unit 22 by the same method as in the second embodiment. For example, the bit rate determining unit 25 can set the bit rate when it is determined that the communication quality is deteriorated to a value obtained by multiplying the current set value by a (for example, 0.5). Further, as shown in FIG. 14, “a” may be made smaller as RTT (TS (j) −TS (i)) becomes larger (as the actual delivery time approaches the allowable condition). When the reception rate included in the response message is used, the bit rate determination unit 25 sets the bit rate to a value obtained by multiplying the reception rate included in the last received response message by b (for example, 0.8). You may do it.

In addition, the data distribution apparatus 20 according to the present embodiment determines whether or not the communication quality is deteriorated every video frame transmission (several tens to hundreds of milliseconds), and lowers the bit rate when the communication quality deteriorates. Therefore, it is possible to quickly detect a deterioration in communication quality and reduce the bit rate.

Next, an operation example of the data distribution apparatus 20 according to the present embodiment will be described with reference to FIGS. It is assumed that the data distribution apparatus 20 has calculated the specified value Dth using Equation 6 in advance.

First, when the data input unit 21 (camera) inputs video data constituting one video frame to the encoding unit 22 (step S301 in FIG. 7), the bit rate determination unit 25 determines whether or not the bit rate needs to be changed. Determine. If a change is necessary (YES in step S302), the bit rate determination unit 25 instructs the encoding unit 22 to change the bit rate (step S303). The encoding unit 22 encodes data at the bit rate specified by the bit rate determining unit 25 (step S304), and the communication unit 23 distributes the encoded data to the data receiving device 40 (step S305).

In step S302, the bit rate determination unit 25 instructs the encoding unit 22 to change the bit rate in the case of a periodic bit rate change timing (YES in step S306 in FIG. 8) (step S303). If it is not a periodic bit rate change timing (NO in step S306), the bit rate determining unit 25 further determines whether or not the communication quality is deteriorated. Then, when the communication quality is deteriorated (YES in step S307), the bit rate determining unit 25 instructs the encoding unit 22 to change the bit rate (step S303). On the other hand, if it has not deteriorated (NO in step S307), the bit rate determination unit 25 does not give an instruction to change the bit rate. Note that the bit rate determining unit 25 can determine the deterioration of the communication quality using Equation 3.

As described above, in the third embodiment of the present invention, the data distribution apparatus 20 performs data distribution when the round trip delay time exceeds the specified value based on the allowable condition regarding the time required for data distribution. Lower the bit rate. Thereby, since the data distribution apparatus 20 uses the prescribed value based on the allowable condition, it is possible to control the bit rate so that the time required for data distribution satisfies the allowable condition. In addition, since the data distribution device 20 uses the round-trip delay time of data, it is possible to detect a deterioration in communication quality more quickly than using a statistical value such as a communication speed and lower the bit rate. Therefore, it is possible to improve the possibility that the time required for data distribution satisfies the allowable condition.

[Fourth embodiment]
Next, a fourth embodiment of the present invention will be described. In the present embodiment, a case will be described in which the network 50 includes a mobile network such as LTE (Long Term Evolution) and a WAN (Wide Area Network) such as the Internet.

In a data distribution system in which the network 50 includes a mobile network or a WAN, communication delay is increased compared to the data distribution system of the third embodiment due to scheduling of communication resources and an increase in transmission distance. In communication via a mobile network and the Internet, the RTT may be several tens of milliseconds to one hundred milliseconds even in a non-congested environment. For example, in an environment where the RTT is 100 ms, it takes at least 100 ms to receive ack after the data distribution device 20 distributes one frame of data. If the specified value Dth is 50 ms in this environment, all frames satisfy Equation 3, so the bit rate determination unit 25 instructs the encoding unit 22 to reduce the bit rate, and as a result, the network 50 is not congested. However, the bit rate will decrease.

In order to prevent this, in the present embodiment, a lower limit is provided for the specified value Dth according to the environment. Assuming that the lower limit value Drt of the prescribed value Dth is the round-trip propagation delay time Drt that is the minimum required for a packet to reciprocate between the data distribution device 20 and the data reception device 40, the condition that the threshold value Dth should satisfy is Equation 8 is obtained.

Therefore, the bit rate determination unit 25 selects the specified value Dth from the range shown in FIG. For example, the bit rate determining unit 25 calculates the specified value Dth using Equation 9. The coefficient c is a value (0 ≦ c <1) determined in advance by the operator.

Note that the data distribution apparatus 20 may transmit the probe packet to the data reception apparatus 40 before the start of video distribution, for example, and use the round-trip delay time of the probe packet as the round-trip propagation delay time Drt. Alternatively, the data distribution device 20 may transmit the probe packet a plurality of times and use the minimum value of the round trip delay time as the round trip propagation delay time Drt. Alternatively, the data distribution apparatus 20 may use, as the round-trip propagation delay time Drt, the minimum value or exponential smoothed value of the RTT calculated based on each video frame and its ack time stamp. When the RTT is exponentially smoothed, an appropriate lower limit value Drt can be maintained even when the communication environment changes (for example, when the communication environment changes from LTE to 3G (Third Generation)).

Other configurations and operations are the same as those in the third embodiment, and a description thereof will be omitted.

As described above, in the fourth embodiment of the present invention, the data distribution device 20 performs data distribution when the round-trip delay time exceeds the specified value based on the allowable condition regarding the time required for data distribution. Lower the bit rate. Thereby, since the data distribution apparatus 20 uses the prescribed value based on the allowable condition, it is possible to control the bit rate so that the time required for data distribution satisfies the allowable condition. In addition, since the data distribution device 20 uses the round-trip delay time of data, it is possible to detect a deterioration in communication quality more quickly than using a statistical value such as a communication speed and lower the bit rate. Therefore, it is possible to improve the possibility that the time required for data distribution satisfies the allowable condition.

In addition, the data distribution apparatus 20 according to the present embodiment provides a lower limit for the specified value Dth that is determined to be a deterioration in communication quality. It becomes possible to prevent the decrease.

[Fifth embodiment]
Next, a fifth embodiment of the present invention will be described. In the present embodiment, a case will be described in which hierarchically encoded video is used.

H. Hierarchical coding method for video. H.264 SVC (Scalable Video Coding) and SHVC (HEVC (High Efficiency Video Coding) Scalable Extension). Decoding of data encoded in the n layers of L (1), L (2),..., L (n) is performed with respect to arbitrary i (1 ≦ i ≦ n) with respect to lower i layer data ( This is possible with L (1),..., L (i)). The smaller the distribution hierarchy number i, the smaller the distribution data amount, but the quality at the time of decoding decreases. On the other hand, when the number of distribution layers i increases, the quality at the time of decoding improves, but the amount of distribution data increases.

The encoding unit 22 of the data distribution apparatus 20 according to the present embodiment hierarchically encodes the video input from the data input unit 21. In addition, the bit rate determining unit 25 instructs the encoding unit 22 of the encoding hierarchical structure and the number of distribution layers.

In the case of regular bit rate change timing (YES in step S306 in FIG. 8), the bit rate determination unit 25 instructs the encoding unit 22 of the bit rate of each layer in step S303 in FIG. For example, when the number of layers n is 3, the bit rate determination unit 25 sets the bit rate of L (1) to the current communication speed −2σ and the bit rate of L (1) + L (2) to the current communication speed −σ. , L (1) + L (2) + L (3) can be the current communication speed. Here, σ is the standard deviation of the communication speed in the past certain time. Note that other methods may be used to determine the bit rate of each layer.

When it is determined that the communication quality has deteriorated (YES in step S307 in FIG. 8), the bit rate determining unit 25 instructs the encoding unit 22 to reduce the number of layers to be distributed (step S303 in FIG. 7).

In this way, the data distribution apparatus 20 can change the bit rate by changing the distribution layer without changing the encoding parameter in the encoding unit 22. As a result, the bit rate can be changed in a shorter time, so that the possibility that the allowable condition can be satisfied can be further improved.

As described above, in the fifth embodiment of the present invention, the data distribution device 20 performs the data distribution when the round-trip delay time exceeds the prescribed value based on the allowable condition related to the time required for data distribution. Lower the bit rate. Thereby, since the data distribution apparatus 20 uses the prescribed value based on the allowable condition, it is possible to control the bit rate so that the time required for data distribution satisfies the allowable condition. In addition, since the data distribution device 20 uses the round-trip delay time of data, it is possible to detect a deterioration in communication quality more quickly than using a statistical value such as a communication speed and lower the bit rate. Therefore, it is possible to improve the possibility that the time required for data distribution satisfies the allowable condition.

In addition, the data distribution device 20 of the present embodiment changes the bit rate by switching the distribution layer. As a result, the bit rate can be changed in a shorter time, so that the possibility that the allowable condition can be satisfied can be further improved.

[Hardware configuration example]
A configuration example of hardware resources that realizes the data distribution apparatuses (10, 20) in each embodiment of the present invention described above using one information processing apparatus (computer) will be described. The data distribution device may be realized using at least two information processing devices physically or functionally. The data distribution device may be realized as a dedicated device. Further, only some functions of the data distribution apparatus may be realized by using the information processing apparatus.

FIG. 16 is a diagram schematically illustrating a hardware configuration example of an information processing apparatus capable of realizing the data distribution apparatus according to each embodiment of the present invention. The information processing device 90 includes a communication interface 91, an input / output interface 92, an arithmetic device 93, a storage device 94, a nonvolatile storage device 95, and a drive device 96.

The communication interface 91 is a communication means for the data distribution device of each embodiment to communicate with an external device by wire or / and wireless. In the case where the data distribution apparatus is realized by using at least two information processing apparatuses, the apparatuses may be connected so as to be able to communicate with each other via the communication interface 91.

The input / output interface 92 is a man-machine interface such as a keyboard that is an example of an input device and a display that serves as an output device.

The arithmetic device 93 is an arithmetic processing device such as a general-purpose CPU (Central Processing Unit) or a microprocessor. For example, the arithmetic device 93 can read various programs stored in the nonvolatile storage device 95 into the storage device 94 and execute processing according to the read programs.

The storage device 94 is a memory device such as a RAM (Random Access Memory) that can be referred to from the arithmetic device 93, and stores programs, various data, and the like. The storage device 94 may be a volatile memory device.

The nonvolatile storage device 95 is a nonvolatile storage device such as a ROM (Read Only Memory) or a flash memory, and can store various programs, data, and the like.

The drive device 96 is, for example, a device that processes reading and writing of data with respect to a recording medium 97 described later.

The recording medium 97 is an arbitrary recording medium capable of recording data, such as an optical disk, a magneto-optical disk, and a semiconductor flash memory.

In each embodiment of the present invention, for example, a data distribution apparatus is configured by the information processing apparatus 90 illustrated in FIG. 16, and a program capable of realizing the functions described in the above embodiments is supplied to the data distribution apparatus. It may be realized by doing.

In this case, the embodiment can be realized by the arithmetic device 93 executing the program supplied to the data distribution device. Also, some of the functions of the data distribution apparatus, not all of the data distribution apparatus, can be configured by the information processing apparatus 90.

Furthermore, the program may be recorded in the recording medium 97, and the program may be appropriately stored in the nonvolatile storage device 95 at the shipping stage or operation stage of the data distribution apparatus. In this case, as the program supply method, a method of installing in the data distribution apparatus using an appropriate jig may be employed in a manufacturing stage before shipment or an operation stage. The program supply method may employ a general procedure such as a method of downloading from the outside via a communication line such as the Internet.

Some or all of the above embodiments may be described as in the following supplementary notes, but are not limited to the following.

(Appendix 1)
Data distribution means for distributing data to the data receiving device;
Response receiving means for receiving a response message for the data from the data receiving device;
The bit rate at the time of distribution of the data when the round trip delay time from the distribution of the data to the reception of the response message exceeds a specified value based on an allowable condition regarding the time required for the distribution of the data And a bit rate determining means for instructing the data distribution means to decrease the data.

(Appendix 2)
The data distribution apparatus according to appendix 1, wherein the specified value is further based on a processing time of the data in the data distribution apparatus and the data reception apparatus.

(Appendix 3)
The data distribution apparatus according to appendix 1 or appendix 2, wherein the specified value is further based on a propagation delay time between the data distribution apparatus and the data reception apparatus.

(Appendix 4)
The data distribution apparatus according to appendix 3, wherein the propagation delay time is based on a result of probe packet transmission / reception.

(Appendix 5)
The data delivery device according to appendix 3, wherein the response message includes the propagation delay time calculated by the data receiving device.

(Appendix 6)
The data distribution apparatus according to any one of appendix 1 to appendix 5, wherein the bit rate determining means calculates the specified value.

(Appendix 7)
The response message includes a reception rate of the data in the data receiving device,
The bit rate determination means determines the bit rate at the time of the distribution of the data based on the reception rate when the round trip delay time exceeds the specified value. The data distribution apparatus according to any one of appendix 6.

(Appendix 8)
The data is video data;
The data distribution device according to any one of appendix 1 to appendix 7, wherein the data distribution unit distributes the video data in units of video frames.

(Appendix 9)
The appendix 8 is characterized in that the bit rate determining means calculates the round trip delay time based on a time stamp difference between the video frame to be distributed next and the video frame having received the response message. The data distribution apparatus described.

(Appendix 10)
The data distribution means hierarchically encodes the data,
The data distribution apparatus according to any one of appendix 1 to appendix 9, wherein the bit rate determining means instructs the decrease of the bit rate by instructing a decrease in the number of layers to be distributed.

(Appendix 11)
The data distribution device according to any one of appendix 1 to appendix 10,
A data distribution system comprising: the data receiving device.

(Appendix 12)
Deliver data to the data receiving device,
Receiving a response message for the data from the data receiving device;
The bit rate at the time of distribution of the data when the round trip delay time from the distribution of the data to the reception of the response message exceeds a specified value based on an allowable condition regarding the time required for the distribution of the data A data distribution method characterized by lowering.

(Appendix 13)
The data distribution method according to appendix 12, wherein the specified value is further based on a processing time of the data in the data distribution device and the data reception device.

(Appendix 14)
14. The data distribution method according to appendix 12 or appendix 13, wherein the specified value is further based on a propagation delay time between the data distribution apparatus and the data reception apparatus.

(Appendix 15)
The data delivery method according to appendix 14, wherein the propagation delay time is based on a result of probe packet transmission / reception.

(Appendix 16)
The data delivery method according to appendix 14, wherein the response message includes the propagation delay time calculated by the data receiving device.

(Appendix 17)
The data distribution method according to any one of appendix 12 to appendix 16, wherein the specified value is calculated.

(Appendix 18)
The response message includes a reception rate of the data in the data receiving device,
18. The appendix 12 to appendix 17, wherein when the round-trip delay time exceeds the specified value, the bit rate for the distribution of the data is determined based on the reception rate. Data delivery method.

(Appendix 19)
The data is video data;
The data distribution method according to any one of appendix 12 to appendix 18, wherein the video data is distributed in units of video frames.

(Appendix 20)
The data delivery method according to appendix 19, wherein the round-trip delay time is calculated based on a time stamp difference between the video frame to be delivered and the video frame having received the response message.

(Appendix 21)
Hierarchically encoding the data;
The data distribution method according to any one of appendix 12 to appendix 20, wherein the bit rate is lowered by reducing the number of layers to be distributed.

(Appendix 22)
On the computer,
A data distribution function for distributing data to a data receiving device;
A response receiving function for receiving a response message to the data from the data receiving device;
The bit rate at the time of distribution of the data when the round trip delay time from the distribution of the data to the reception of the response message exceeds a specified value based on an allowable condition regarding the time required for the distribution of the data A computer-readable recording medium on which a data distribution program is recorded, characterized in that a bit rate determination function for instructing the data distribution function to lower the data is realized.

(Appendix 23)
The computer-readable recording medium storing the data distribution program according to appendix 22, wherein the specified value is further based on a processing time of the data in the data distribution apparatus and the data reception apparatus.

(Appendix 24)
The prescribed value is further based on a propagation delay time between the data distribution device and the data reception device. The computer-readable recording medium on which the data distribution program according to the supplementary note 22 or the supplementary note 23 is recorded.

(Appendix 25)
The computer-readable recording medium recording the data distribution program according to appendix 24, wherein the propagation delay time is based on a result of probe packet transmission / reception.

(Appendix 26)
The computer-readable recording medium recording the data distribution program according to appendix 24, wherein the response message includes the propagation delay time calculated by the data receiving device.

(Appendix 27)
The bit rate determining function calculates the specified value. A computer-readable recording medium on which the data distribution program according to any one of appendix 22 to appendix 26 is recorded.

(Appendix 28)
The response message includes a reception rate of the data in the data receiving device,
From the appendix 22, the bit rate determination function determines the bit rate at the time of the distribution of the data based on the reception rate when the round-trip delay time exceeds the specified value. A computer-readable recording medium on which the data distribution program according to any one of Appendix 27 is recorded.

(Appendix 29)
The data is video data;
The data distribution function distributes the video data in units of video frames. A computer-readable recording medium on which the data distribution program according to any one of appendix 22 to appendix 28 is recorded.

(Appendix 30)
The appendix 29 is characterized in that the bit rate determination function calculates the round-trip delay time based on a time stamp difference between the video frame to be distributed next and the video frame having received the response message. A computer-readable recording medium on which the described data distribution program is recorded.

(Appendix 31)
The data distribution function hierarchically encodes the data,
The data distribution program according to any one of Supplementary Note 22 to Supplementary Note 30, wherein the bit rate determination function directs a decrease in the bit rate by instructing a decrease in the number of layers to be distributed. Computer-readable recording medium.

The present invention has been described above with reference to the embodiments, but the present invention is not limited to the above embodiments. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

This application claims priority based on Japanese Patent Application No. 2018-025331 filed on Feb. 15, 2018, the entire disclosure of which is incorporated herein.

DESCRIPTION OF

SYMBOLS

10, 20 Data delivery apparatus 11 Data delivery part 12 Response receiving part 13 Bit rate determination part 21 Data input part 22 Encoding part 23 Communication part 24 Communication quality measurement part 25 Bit rate determination part 40 Data reception apparatus 41 Communication part 42 Decoding part 43 Data Output Unit 44 Response Generation Unit 50 Network 60 Communication Device 90 Information Processing Device 91 Communication Interface 92 Input / Output Interface 93 Arithmetic Device 94 Storage Device 95 Nonvolatile Storage Device 96 Drive Device 97 Recording Medium

Claims

Data distribution means for distributing data to the data receiving device;
Response receiving means for receiving a response message for the data from the data receiving device;
The bit rate at the time of distribution of the data when the round trip delay time from the distribution of the data to the reception of the response message exceeds a specified value based on an allowable condition regarding the time required for the distribution of the data And a bit rate determining means for instructing the data distribution means to decrease the data.
The data distribution apparatus according to claim 1, wherein the specified value is further based on a processing time of the data in the data distribution apparatus and the data reception apparatus.
The data distribution apparatus according to claim 1, wherein the specified value is further based on a propagation delay time between the data distribution apparatus and the data reception apparatus.
The data distribution apparatus according to claim 3, wherein the propagation delay time is based on a result of probe packet transmission / reception.
The data distribution device according to claim 3, wherein the response message includes the propagation delay time calculated by the data receiving device.
The data distribution apparatus according to any one of claims 1 to 5, wherein the bit rate determining means calculates the specified value.
The response message includes a reception rate of the data in the data receiving device,
The bit rate determining means determines the bit rate for the distribution of the data based on the reception rate when the round trip delay time exceeds the specified value. The data distribution apparatus according to claim 6.
The data is video data;
The data distribution device according to any one of claims 1 to 7, wherein the data distribution unit distributes the video data in units of video frames.
The bit rate determining means calculates the round trip delay time based on a time stamp difference between the video frame to be distributed next and the video frame having received the response message. The data distribution device described in 1.
The data distribution means hierarchically encodes the data,
The data distribution apparatus according to any one of claims 1 to 9, wherein the bit rate determination unit instructs the decrease of the bit rate by instructing a decrease in the number of layers to be distributed.
A data distribution device according to any one of claims 1 to 10,
A data distribution system comprising: the data receiving device.
Deliver data to the data receiving device,
Receiving a response message for the data from the data receiving device;
The bit rate at the time of distribution of the data when the round trip delay time from the distribution of the data to the reception of the response message exceeds a specified value based on an allowable condition regarding the time required for the distribution of the data A data distribution method characterized by lowering.
The data distribution method according to claim 12, wherein the specified value is further based on a processing time of the data in the data distribution device and the data reception device.
The data distribution method according to claim 12 or 13, wherein the specified value is further based on a propagation delay time between the data distribution device and the data reception device.
The data delivery method according to claim 14, wherein the propagation delay time is based on a result of probe packet transmission / reception.
The data delivery method according to claim 14, wherein the response message includes the propagation delay time calculated by the data receiving device.
The data distribution method according to any one of claims 12 to 16, wherein the prescribed value is calculated.
The response message includes a reception rate of the data in the data receiving device,
18. The bit rate for the distribution of the data is determined based on the reception rate when the round-trip delay time exceeds the specified value. 18. The data distribution method described in 1.
The data is video data;
The data distribution method according to any one of claims 12 to 18, wherein the video data is distributed in units of video frames.
The data delivery method according to claim 19, wherein the round-trip delay time is calculated based on a time stamp difference between the video frame to be delivered and the video frame that has received the response message.
Hierarchically encoding the data;
The data delivery method according to any one of claims 12 to 20, wherein the bit rate is lowered by reducing the number of layers to be delivered.
On the computer,
A data distribution function for distributing data to a data receiving device;
A response receiving function for receiving a response message to the data from the data receiving device;
The bit rate at the time of distribution of the data when the round trip delay time from the distribution of the data to the reception of the response message exceeds a specified value based on an allowable condition regarding the time required for the distribution of the data A computer-readable recording medium on which a data distribution program is recorded, characterized in that a bit rate determination function for instructing the data distribution function to lower the data is realized.
The computer-readable recording medium recording the data distribution program according to claim 22, wherein the specified value is further based on a processing time of the data in the data distribution apparatus and the data reception apparatus.
24. The computer-readable record in which the data distribution program according to claim 22 or 23 is recorded, wherein the specified value is further based on a propagation delay time between the data distribution device and the data reception device. Medium.
The computer-readable recording medium recording the data distribution program according to claim 24, wherein the propagation delay time is based on a result of probe packet transmission / reception.
The computer-readable recording medium recording the data distribution program according to claim 24, wherein the response message includes the propagation delay time calculated by the data receiving device.
The computer-readable recording medium recording the data distribution program according to any one of claims 22 to 26, wherein the bit rate determining function calculates the specified value.
The response message includes a reception rate of the data in the data receiving device,
The bit rate determination function determines the bit rate for the distribution of the data based on the reception rate when the round trip delay time exceeds the specified value. A computer-readable recording medium on which the data distribution program according to claim 27 is recorded.
The data is video data;
The computer-readable recording medium recording the data distribution program according to any one of claims 22 to 28, wherein the data distribution function distributes the video data in units of video frames.
30. The round trip delay time is calculated based on a time stamp difference between the video frame to be distributed next and the video frame having received the response message. A computer-readable recording medium on which the data distribution program described in 1 is recorded.
The data distribution function hierarchically encodes the data,
The data distribution program according to any one of claims 22 to 30, wherein the bit rate determination function instructs a decrease in the bit rate by instructing a decrease in the number of layers to be distributed. A recorded computer-readable recording medium.