JP2023019869A - Transmitter and communication system - Google Patents

Abstract

To provide a configuration that makes it little for a receiving side to process frames which are not in time for video reproduction in a transmitter that transmits frames of video data.SOLUTION: A transmitter includes a processing device and a communication device. The processing device creates frames of video data. The communication device transmits the frames created by the processing device to a receiver. The processing device determines whether the frames correspond to delayed frames which are not in time for video reproduction on a receiving side. The communication device omits processing to transmit a delayed frame to the receiver, and transmits a frame after the delayed frame to the receiver.SELECTED DRAWING: Figure 5

Description

The present invention mainly relates to transmitters for transmitting video data.

Patent Literature 1 discloses a video data delivery system. On the transmission side of the video data distribution system, packet data of image frames arranged along the time axis without being compressed in the direction of the time axis are transmitted. On the transmitting side, the queuing process of buffering packet data and transmitting packets according to the available band is performed until the packet data corresponding to the next image frame is buffered.

Japanese Unexamined Patent Application Publication No. 2013-81020

In the video data distribution system of Patent Document 1, for example, when the data amount of packet data is too large for the communication speed, there is a possibility that frames that cannot be reproduced in time on the receiving side are frequently transmitted.

For example, in the case of reproducing video with a low delay, even if a frame is transmitted that cannot be reproduced in time on the receiving side, this frame will not be reproduced on the receiving side. That is, there is a possibility that the receiving side frequently performs processing related to frames that cannot be reproduced in time (that is, unnecessary processing).

The present invention has been made in view of the above circumstances, and its main object is to provide a transmitter that transmits frames of video data so that it is difficult for the receiving side to process frames that are not in time for video reproduction. to provide.

Means and Effects for Solving Problems

The problems to be solved by the present invention are as described above. Next, the means for solving the problems and the effects thereof will be described.

A first aspect of the present invention provides a transmitter configured as follows. That is, the transmitter comprises a processing device and a communication device. The processing device creates frames of video data. The communication device transmits the frames created by the processing device to a receiver. The processing device determines whether or not the frame corresponds to a delayed frame which is not in time for video reproduction on the receiving side. The communication device skips the process of transmitting the delayed frame to the receiver, and transmits the frame after the delayed frame to the receiver.

As a result, a delay frame that is not in time for video reproduction on the receiving side is not transmitted, so that transmission of unnecessary data and unnecessary processing on the receiving side can be prevented.

The transmitter preferably has the following configuration. That is, the frame created by the processing device includes a differential frame created based on the difference from the previously transmitted frame. The processing device creates, as the frame to be transmitted after the delayed frame, the difference frame created based on the difference from the frame before the delayed frame.

As a result, a differential frame suitable for video reproduction on the receiver can be created.

The transmitter preferably has the following configuration. That is, the processing device stores a preset communication regulation time. The processing device determines whether or not the frame corresponds to a delayed frame which is not in time for video reproduction on the receiving side, based on whether or not the transmission time of the frame exceeds the specified communication time.

With this, it is possible to determine whether or not the frame corresponds to the delayed frame by a simple method.

In the transmitter, based on whether or not the total transmission time of the frame from the past to the present exceeds the total communication prescribed time from the past to the present, the current frame is transmitted to the receiving side. It is preferable to determine whether or not the frame corresponds to a delayed frame that is not in time for video playback.

As a result, for example, when the data size of the frame transmitted immediately before is small, it is possible to determine whether or not the frame to be transmitted next is a delayed frame by considering the remaining time. That is, compared to the case where it is determined whether or not the specified communication time is exceeded for each frame, the frequency of occurrence of delayed frames can be reduced.

In the transmitter, it is preferable that the processing device determines whether the transmission time of the frame exceeds the communication regulation time after the entire encoding of the frame is completed.

As a result, the number of determinations can be reduced compared to the case where determination is performed each time encoding in units of slices is completed.

In the transmitter, it is preferable that the processing device determines whether or not the transmission time of the frame exceeds the communication regulation time each time encoding in units of slices obtained by dividing the frame is completed.

As a result, it is possible to quickly determine whether or not the frame corresponds to the delayed frame, as compared with the case where the determination is performed after the encoding of the entire frame is completed.

The transmitter preferably has the following configuration. That is, the image data is data representing an image captured by the image capturing device. The communication device transmits in real time the frame based on the video data received from the imaging device to the receiver.

As a result, it is possible to effectively utilize the effect that video delay is less likely to occur.

According to a second aspect of the present invention there is provided a communication system comprising said transmitter and said receiver.

As a result, a system capable of transmitting video with low delay can be realized.

The communication system described above preferably has the following configuration. That is, the receiver requests a new key frame from the transmitter when the frame received from the transmitter is missing. The transmitter transmits the new keyframes to the receiver after receiving a request from the receiver. The receiver does not display the image based on the received frame after receiving the frame with the missing frame until receiving the new key frame, and then displays the image based on the new key frame. do.

As a result, the image based on the missing frame or the frame referencing the frame is not displayed, so that it is possible to prevent the image from being disturbed.

The communication system described above preferably has the following configuration. In other words, the image data is data representing an image of a situation in which the working device is working. The receiver transmits commands for the work device to the transmitter. The transmitter causes the work device to perform work based on the command.

As a result, video delay is less likely to occur, so that the work device can be made to perform efficient and accurate work.

1 is a block diagram of a communication system according to one embodiment of the present invention; FIG. 4 is a flowchart showing processing performed by a transmitter regarding transmission of the Nth frame. FIG. 10 is a diagram showing the data amount of each frame and the specified communication time in situation A; FIG. 10 is a diagram showing the data amount of each frame and the specified communication time in situation B; FIG. 10 is a diagram showing the data amount of each frame and the specified communication time in situation C; 4 is a flow chart showing the processing performed by the receiver regarding an IDR request. FIG. 4 illustrates transmitter and receiver processing when making an IDR request. 10 is a flowchart showing processing performed by a transmitter regarding transmission of the N-th frame in a modified example in which encoding is performed in units of slices;

Embodiments of the present invention will now be described with reference to the drawings. First, a communication system 1 according to this embodiment will be described with reference to FIG.

A communication system 1 is provided in a workplace such as a factory, facility, or office, for example. A communication system 1 includes a transmitter 10 and a receiver 20 . Transmitter 10 and receiver 20 are connected to the same local area network and can communicate with each other. Note that the transmitter 10 and the receiver 20 may be connected via the Internet or the like.

The transmitter 10 includes a processing device 10a and a communication device 10b. The processing device 10a includes a CPU, ROM, RAM, and the like. The processing device 10a can execute various processes by reading programs stored in the ROM into the RAM and executing them by the CPU. For example, the processing device 10a can perform a process of encoding video data, a process of instructing the communication device 10b to transmit and receive data, and the like. The communication device 10b is a communication module for performing wired communication or wireless communication. A working device 11 and a photographing device 12 are connected to the transmitter 10 .

The working device 11 is a device for performing work in the workshop. The working device 11 is, for example, a machine tool or a robot. The work device 11 has an actuator, and performs work by operating the actuator based on a command (electrical signal) input from the outside.

The photographing device 12 photographs a situation in which the work device 11 is working and creates video data. The imaging device 12 is, for example, a video camera. The imaging device 12 is attached to, for example, a pillar or a workbench, and creates video data including the work device 11 . Note that the imaging device 12 may be attached to the work device 11 to create image data including the work target of the work device 11 . The imaging device 12 transmits the created video data to the transmitter 10 . The transmitter 10 compresses the video data and transmits it to the receiver 20 .

Receiver 20 has substantially the same configuration as transmitter 10 . A display device 21 and an operation device 22 are connected to the receiver 20 . The receiver 20 transmits the video data received from the transmitter 10 to the display device 21 .

The display device 21 is, for example, a liquid crystal display or an organic EL display. The display device 21 displays the video data received from the receiver 20 on the screen.

The operating device 22 is a device for the operator to operate the work device 11 . The operating device 22 may be a lever and buttons or the like, or may be a touch panel. The operator moves the lever or the like of the operation device 22 while watching the image displayed on the display device 21 . As a result, a command (electrical signal) for operating the work device 11 is transmitted from the operating device 22 to the receiver 20 . Receiver 20 sends commands to transmitter 10 . The transmitter 10 transmits commands to the work device 11 . As described above, the worker can operate the work device 11 based on the operation performed on the operation device 22 while viewing the state of the work device 11 displayed on the display device 21 .

In the present embodiment, the worker operates the work device 11 while looking at the display device 21. Therefore, when the video delay is large, for example, it is difficult for the worker to operate the work device 11 appropriately. Therefore, it is required to transmit and display video with low delay (in other words, real-time video). In this specification, the term "real time" does not only indicate a strictly synchronized situation, but also indicates a situation in which a slight delay (for example, a delay of 1 second or less) occurs according to the communication time or processing time. terminology.

Processing performed by the transmitter 10 in order to achieve low video delay will be described below with reference to FIGS. 2 to 5. FIG.

The processing device 10 a of the transmitter 10 changes the compression rate when transmitting video data based on the communication speed between the transmitter 10 and the receiver 20 . For example, when the communication speed between the transmitter 10 and the receiver 20 decreases and falls below the threshold, the processing device 10a reduces the compression rate of video data by one step. As a result, it is possible to suppress video delay caused by a decrease in communication speed. In addition, in a situation where the communication speed is always stable, the communication speed may be substantially constant and the compression ratio may be a fixed value.

The processing device 10a processes and compresses the video data received from the imaging device 12 on a frame-by-frame basis. Specifically, the frames include key frames (I frames) and differential frames (P frames). A key frame is a frame created without inter-frame prediction. A keyframe contains all the information of the corresponding frame, and the corresponding frame can be displayed by the keyframe alone. A difference frame is a frame created based on a difference from a temporally previous frame (key frame or difference frame, hereinafter referred to as a reference frame). A difference frame contains only information about the difference from the reference frame. Therefore, the relevant frame can be displayed based on both the difference frame and the reference frame. Note that the difference frame in this embodiment is basically the previous frame, but may be the previous frame by two or more.

The amount of data in the difference frame is not constant because it depends on the difference from the reference frame. Therefore, for example, if the amount of data in the differential frame is too large, the timing at which the receiver 20 receives the differential frame is delayed, and the timing at which the differential frame is processed is delayed. As a result, the reproduction of the video on the receiving side (specifically, the display device 21) does not keep up. If the video is to be played back in real time, this differential frame is not played back. That is, on the receiving side (specifically, receiver 20), processing for reproduction (unnecessary processing) is performed even though reproduction is not possible. In order to suppress this, the transmitter 10 of the present embodiment omits transmission of frames that cannot be reproduced on the receiving side. A specific description will be given below.

A process for determining whether or not to transmit the Nth frame will be described below. The N-th frame is a differential frame, and the previous (N-1)-th frame is a reference frame. First, as shown in FIG. 2, the processing device 10a encodes the Nth frame using the (N−1)th frame as a reference frame (S101).

Next, the processing device 10a determines whether or not the time (predicted) that it will take to transmit the N-th frame (hereinafter referred to as transmission time) exceeds the specified communication time (S102). By encoding the Nth frame, the data amount of the Nth frame is determined. Therefore, the processing device 10 a calculates the transmission time of the Nth frame based on the data amount of the Nth frame and the communication speed between the transmitter 10 and the receiver 20 .

The specified communication time is a predetermined length of time. If the transmission time of the frame by the transmitter 10 does not exceed the communication regulation time, the reception side can reproduce the frame in time. Therefore, the specified communication time is the time from the time of one frame (approximately 16.6 msec when the frame rate is 60 FPS) to the time from the completion of transmission by the transmitter 10 to the completion of reception by the receiver 20. This is the time obtained by subtracting the processing time in , and the overhead time of each processing. Since it is difficult to accurately calculate these times, values obtained experimentally or empirically may be used as the specified communication times. Also, the specified communication time may be a fixed value, or may be changed according to the communication speed.

Here, with reference to FIGS. 3 to 5, determination of the transmission time and the specified communication time will be specifically described. As shown in FIGS. 3 to 5, the specified communication time is determined for each frame rate. The specified communication time for each frame rate is constant. The frame times shown in FIGS. 3 to 5 are divided into a plurality of sections. Each segment is one frame time (eg, about 16.6 msec if the frame rate is 60 FPS). As described above, the specified communication time is shorter than the time of one frame. The frame data amount (transmission time) is obtained by converting the frame data amount to be encoded and transmitted into the transmission time. In other words, if the frame data amount (transmission time) is longer than the specified communication time, the frame transmission time exceeds the specified communication time.

In situation A shown in FIG. 3, frames (1) to (4) do not exceed the specified communication time. That is, by transmitting frames (1) to (4), each frame is reproduced in real time on the receiving side.

In situation B shown in FIG. 4, the transmission time of frame (1) is the same as the communication regulation time. The transmission time of frame (2) is shorter than the communication regulation time by time T2. The transmission time of frame (3) is longer than the communication regulation time by time T3. The transmission time of frame (3) exceeds the communication regulation time. However, there is a margin of time T2 at the time of transmission of frame (2). And time T2 is longer than time T3. In other words, by utilizing the time left in the transmission of frame (2), frame (3) can be transmitted without exceeding the specified communication time.

In other words, in the determination in step S102 shown in FIG. 2, it is preferable to determine whether or not the transmission time of the N-th frame exceeds the specified communication time in consideration of the margin of the specified communication time that occurred in the past. In other words, it is preferable to determine whether or not the time when the transmission of the Nth frame is completed is later than the communication regulation time of the Nth frame. Specifically, the processing device 10a makes the determination in step S102 based on whether or not the total frame transmission time from the past to the present exceeds the total specified communication time from the past to the present. conduct. The starting point of the past may be, for example, the time of transmission of the previous frame, the time of transmission of the next frame of the most recent key frame, or the time of transmission of the next frame of the most recent delayed frame (details will be described later). frame is transmitted. Also, an average may be used instead of the total. Since the value obtained by dividing the total by the corresponding number is the average, comparison of totals and comparison of averages have substantially the same meaning in this determination.

As shown in FIG. 2, the processing device 10a determines whether or not the transmission time of the Nth frame exceeds the specified communication time. The frame is transmitted to the receiver 20 (S103). Then, the processing device 10a repeats the same processing for the (N+1)-th and subsequent frames.

In situation C shown in FIG. 5, the transmission times of frame (1) and frame (2) are substantially the same as the specified communication time, and the transmission time of frame (4) does not exceed the specified communication time. The transmission time of frame (3) exceeds the communication regulation time by time T3. Therefore, in step S102 shown in FIG. 2, the processing device 10a determines that the transmission time of frame (3) exceeds the specified communication time.

When the processing device 10a determines that the transmission time of the Nth frame exceeds the communication regulation time (Yes in S102), it stops transmission of the Nth frame (S104). This is because even if the N-th frame is transmitted, the processing on the receiving side cannot be completed in time, which leads to unnecessary data transmission and unnecessary data processing. This frame is hereinafter referred to as a delayed frame.

Next, the processing device 10a encodes the (N+1)th frame using the (N−1)th frame as a reference frame (S105). This is because the Nth frame is not transmitted to the receiver 20, so even if the Nth frame is used as a reference frame, it cannot be processed on the receiving side. Next, the processing device 10a transmits the N+1th frame created in step S105 to the receiver 20 (S106). Then, the processing device 10a repeats the same processing for the (N+2)-th and subsequent frames. Although one frame after the delayed frame in this embodiment is transmitted to the receiver 20 , two or more frames after it may be transmitted to the receiver 20 .

Also in situation C described above, frame (3) is determined to be a delayed frame. Therefore, frame (3) is not transmitted. Then, frame (4) is encoded and transmitted using frame (2) as a reference frame.

Next, with reference to FIGS. 6 and 7, processing performed on the receiving side for suppressing disturbance of the image displayed on the display device 21 will be described.

Packet loss may occur during communication between the transmitter 10 and the receiver 20 . In that case, there is a possibility that the processing device 10a encodes the video data and some of the data constituting the frame transmitted by the communication device 10b does not reach the receiver 20. FIG. When a frame to be received by the receiver 20 is missing in this way, the frame cannot be reproduced, and therefore the video cannot be properly reproduced. Also, since this frame is missing, the next difference frame that references this frame cannot be reproduced properly.

In order to avoid this situation, the receiver 20 determines whether or not the frame received from the transmitter 10 is missing (S201). Then, an IDR request is sent to the transmitter 10 without performing the processing to do so (S202).

IDR stands for Instantaneous Decoder Refresh. When the transmitter 10 receives the IDR request, the transmitter 10 sets the frame of the next frame time as the IDR frame. IDR frames are key frames. In addition, the frame to be created from now on does not use the frame before the IDR frame as a reference frame. After creating the IDR frame, the transmitter 10 transmits the IDR frame to the receiver 20 .

The receiver 20 does not update the display of the display device 21 until receiving the IDR frame (S203). This is because, as described above, even if a frame with a missing frame is displayed or a frame with a missing frame is used as a reference frame, the image will be disturbed. Thereafter, after receiving the IDR frame, the receiver 20 updates the display on the display device 21 with the received IDR frame (S204).

FIG. 7 shows an example of processing related to IDR. As shown in FIG. 7, when the frame (1) received by the receiver 20 is missing, the receiver 20 makes an IDR request. Since the transmitter 10 received the IDR request while processing the frame (4), it transmits the next frame (5) to the receiver 20 as an IDR frame (key frame). The receiver 20 does not display the frames (2), (3), and (4) received from the transmitter 10 before receiving the missing frame (1) and the IDR frame.

As described above, it is possible to recover the influence of missing frames while preventing image distortion.

Next, a modification of the above embodiment will be described with reference to FIG. The equipment constituting the communication system 1 of the following modification is the same as that of the above embodiment.

The processing device 10a of the above embodiment performs encoding on a frame-by-frame basis. On the other hand, the processing device 10a of the modified example performs encoding in units of slices obtained by dividing a frame. By performing encoding in units of slices, it is possible to quickly determine whether or not the frame transmission time exceeds the communication regulation time.

Specifically, after encoding the Mth slice of the Nth frame (S301), the processing device 10a calculates the transmission time from the total amount of data from the first slice to the Mth slice of the Nth frame (S302). ).

Next, the processing device 10a determines whether or not the transmission time calculated in step S302 exceeds the specified communication time (S303). For this determination, the margin of the past specified communication time shown in the above embodiment may be taken into consideration.

If the transmission time does not exceed the specified communication time, the processing device 10a encodes the next slice, that is, the M+1-th slice. Then, the processing device 10a repeats the same processing for the (M+1)-th slice of the N-th frame and thereafter. Also, when the processing for the last slice is completed, the Nth frame is transmitted.

On the other hand, if the transmission time exceeds the specified communication time, the processing device 10a stops transmitting the Nth frame (S304). In this case, since the encoding of the Nth frame is unnecessary, the processing device 10a omits the encoding of the M+1th slice and subsequent slices of the Nth frame. Thereafter, the processing device 10a encodes each slice of the (N+1)th frame using the (N−1)th frame as a reference frame, as in the above embodiment.

In the transmitter 10 of the modified example, for example, when the transmission time of the Nth frame exceeds the communication regulation time, it can be detected before the encoding of the entire Nth frame is completed. Therefore, since determination can be made at an early timing, encoding of the (N+1)th frame can be started at an early timing.

As described above, the transmitter 10 of this embodiment includes the processing device 10a and the communication device 10b. The processing device 10a creates frames of video data. The communication device 10b transmits the frame created by the processing device 10a to the receiver 20 . The processing device 10a determines whether or not the frame corresponds to a delayed frame which is too late for video reproduction on the receiving side. The communication device 10 b omits the process of transmitting the delayed frame to the receiver 20 and transmits the frame after the delayed frame to the receiver 20 .

As a result, a delay frame that is not in time for video reproduction on the receiving side is not transmitted, so that transmission of unnecessary data and unnecessary processing on the receiving side can be prevented.

In the transmitter 10 of this embodiment, the frame created by the processing device 10a includes a differential frame created based on the difference from the previously transmitted frame. As a frame to be transmitted after the delayed frame, the processing device 10a creates a difference frame created based on the difference from the frame before the delayed frame.

As a result, a differential frame suitable for video reproduction on the receiver can be created.

In the transmitter 10 of this embodiment, the processing device 10a stores a preset communication regulation time. The processing device 10a determines whether or not the frame corresponds to a delayed frame that is not in time for video reproduction on the receiving side, based on whether or not the transmission time of the frame exceeds the specified communication time.

With this, it is possible to determine whether or not the frame corresponds to the delayed frame by a simple method.

In the transmitter 10 of the present embodiment, based on whether the total transmission time of frames from the past to the present exceeds the total communication specified time from the past to the present. It is determined whether or not the frame corresponds to a delayed frame that is not in time for playback.

As a result, for example, when the data size of the frame transmitted immediately before is small, it is possible to determine whether or not the frame to be transmitted next is a delayed frame by considering the remaining time. That is, compared to the case where it is determined whether or not the specified communication time is exceeded for each frame, the frequency of occurrence of delayed frames can be reduced.

In the transmitter 10 of this embodiment, the processing device 10a determines whether or not the transmission time of the frame exceeds the specified communication time after the encoding of the entire frame is completed.

As a result, the number of determinations can be reduced compared to the case where determination is performed each time encoding in units of slices is completed.

In the transmitter 10 of the modified example of the present embodiment, the processing device 10a determines whether or not the transmission time of the frame exceeds the specified communication time each time encoding is completed in units of slices obtained by dividing the frame.

As a result, it is possible to quickly determine whether or not the frame corresponds to the delayed frame, as compared with the case where the determination is performed after the encoding of the entire frame is completed.

In the transmitter 10 of the present embodiment, the video data is data representing the video captured by the imaging device 12 . The communication device 10b transmits frames based on the video data received from the imaging device 12 to the receiver 20 in real time.

As a result, it is possible to effectively utilize the effect that video delay is less likely to occur.

A communication system 1 of this embodiment includes a transmitter 10 and a receiver 20 .

As a result, a system capable of transmitting video with low delay can be realized.

In the communication system 1 of this embodiment, the receiver 20 requests a new key frame from the transmitter 10 when the frame received from the transmitter 10 is missing. The transmitter 10 transmits new keyframes to the receiver 20 after receiving the request from the receiver 20 . The receiver 20 does not display the image based on the frames received after receiving the missing frame until receiving the new keyframe, and displays the image based on the new keyframe next.

As a result, the image based on the missing frame or the frame referencing the frame is not displayed, so that it is possible to prevent the image from being disturbed.

In the communication system 1 of the present embodiment, the image data is data representing an image of a situation in which the work device 11 is working. The receiver 20 transmits commands to the work device 11 to the transmitter 10 . The transmitter 10 causes the work device 11 to perform work based on the command.

As a result, video delay is less likely to occur, and the work device 11 can be made to perform the work efficiently and accurately.

Although the preferred embodiments of the present invention have been described above, the above configuration can be modified, for example, as follows.

In the above-described embodiment, in the determination in step S102, the margin of the specified communication time that occurred in the past is taken into consideration. Alternatively, the judgment in step S102 may be made based only on the transmission time of the frame being judged and the communication regulation time without considering the margin of the communication regulation time that occurred in the past.

In the above-described embodiment, when taking into consideration the margin of the communication regulation time that occurred in the past, an example was shown in which the total value of the margin of the communication regulation time and the total value of the frame transmission time were used. may be used. The average value is the sum divided by the count.

In the above embodiment, it is determined whether or not the N-th frame corresponds to the delay frame using the communication regulation time, which is a predetermined fixed value. Alternatively, a communication lag or the like occurring in real time due to communication between the transmitter 10 and the receiver 20 is estimated, and the Nth frame is delayed based on the communication lag, communication speed, frame data amount, and the like. You may judge whether it corresponds to a frame.

The flowcharts shown in the above embodiments are examples, and some of the processes may be omitted, the contents of some of the processes may be changed, or new processes may be added. For example, if the Nth frame was a delayed frame, then a key frame may be sent.

In the above embodiment, the transmitter 10, the work device 11, and the imaging device 12 are separate pieces of hardware, but at least two of them may be realized by one piece of hardware. For example, the function of the transmitter 10 can be incorporated into the working device 11, or the function of the imaging device 12 can be incorporated into the transmitter 10. FIG. Similarly, in the above embodiment, the receiver 20, the display device 21, and the operation device 22 are separate pieces of hardware, but at least two of them may be realized by one piece of hardware. For example, the functions of the receiver 20 can be incorporated into the display device 21 and the functions of the receiver 20 can be incorporated into the operation device 22 .

In the above embodiment, the present invention is applied to a system that remotely operates the work device 11, but the present invention may be applied to another system. For example, the present invention can also be applied to a system that transmits video from surveillance cameras.

1 communication system 10 transmitter 10a processing device 10b communication device 20 receiver

Claims (10)

a processor for creating frames of video data;
a communication device that transmits the frame created by the processing device to a receiver;
with
The processing device determines whether or not the frame corresponds to a delayed frame not in time for video reproduction on the receiving side,
A transmitter, wherein the communication device omits a process of transmitting the delayed frame to the receiver, and transmits the frame after the delayed frame to the receiver. A transmitter according to claim 1, wherein
the frame created by the processing device includes a difference frame created based on a difference from the previously transmitted frame;
The transmitter according to claim 1, wherein the processing device creates, as the frame to be transmitted after the delayed frame, the difference frame created based on a difference from the frame before the delayed frame. A transmitter according to claim 1 or 2,
The processing device stores a preset communication regulation time,
The processing device determines whether or not the frame corresponds to a delayed frame which is not in time for video reproduction on the receiving side, based on whether or not the transmission time of the frame exceeds the specified communication time. Transmitter characterized by: A transmitter according to claim 3, wherein
A delay in which the current frame is not in time for video reproduction on the receiving side, based on whether or not the total transmission time of the frame from the past to the present exceeds the total communication prescribed time from the past to the present. A transmitter that determines whether or not it corresponds to a frame. A transmitter according to claim 3 or 4,
The transmitter, wherein the processing device determines whether or not the transmission time of the frame exceeds the communication regulation time after the encoding of the entire frame is completed. A transmitter according to claim 3 or 4,
The transmitter, wherein the processing device determines whether or not the transmission time of the frame exceeds the specified communication time each time encoding is completed in units of slices obtained by dividing the frame. A transmitter according to any one of claims 1 to 6,
The image data is data representing an image captured by a camera,
A transmitter, wherein the communication device transmits the frames based on the video data received from the photographing device to the receiver in real time. a transmitter according to any one of claims 1 to 7;
the receiver;
A communication system comprising: A communication system according to claim 8,
the receiver requests a new key frame from the transmitter when the frame received from the transmitter is defective;
the transmitter transmitting the new keyframes to the receiver after receiving a request from the receiver;
The receiver does not display the image based on the received frame after receiving the frame with the missing frame until receiving the new key frame, and then displays the image based on the new key frame. A communication system characterized by performing processing for A communication system according to claim 8 or 9,
The image data is data representing an image of a situation in which the work device is working, and
the receiver transmits commands for the work device to the transmitter;
The communication system, wherein the transmitter causes the work device to perform work based on the command.

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