Ad-hoc network-based monitoring app data transmission method

Abstract

The invention discloses a monitoring app data transmission method based on an ad hoc network, and relates to the technical field of data transmission, and the method comprises monitoring equipment, and also comprises the following steps: S1, transmitting data collected by the monitoring equipment to equipment carrying a monitoring app; s2, if the real-time monitoring is not needed, reducing the frame rate to reduce the generation speed of the data; s3, starting to transmit a video when the motion is detected by using a motion detection technology; s4, reducing data through a video compression algorithm; and S5, performing data transmission between the monitoring apps in a binary transmission mode, and receiving and sending data by adopting a private protocol in which a UDP (User Datagram Protocol) is matched with a TCP (Transmission Control Protocol). According to the method, binary data transmission is adopted, compared with data in a JSON format, the data size needing to be transmitted is reduced, and the reliability and transmission efficiency of data transmission are improved by adopting a private protocol that UDP is matched with TCP.

Description

Technical Field

[0001] The present invention relates to the technical field of data transmission, and in particular to a monitoring app data transmission method based on a self-organizing network. Background Art

[0002] Traditional communication monitoring apps usually use 4g / 5g Internet communication. In terms of communication and data transmission, they may be limited by the coverage of the network and the stability of the network signal, which may lead to communication interruption or large communication delay. In order to overcome this problem, some devices equipped with monitoring apps will communicate through ad hoc networks. In ad hoc network communication, the monitoring app enters the network by connecting to the wifi / Ethernet of the ad hoc network device, which is conducive to improving the stability of the communication process. The monitoring device will transmit the video data to the monitoring app after capturing the image. The monitoring app that receives the video can send the video or voice or text information to another monitoring app, thereby achieving communication between monitoring apps.

[0003] However, when traditional monitoring apps transmit data during communication, the data format is mostly in JSON format. Although this method is convenient for data parsing, it will bring the following problems: 1) Data redundancy: JSON is a text format that contains a lot of redundant information when representing data, such as brackets, quotation marks, colons and commas, etc. These characters are not necessary for the transmission of the data itself, but they are necessary to ensure the readability and structure of the data. The JSON format usually requires more bytes to represent the same data; 2) Increased transmission delay: On the sender, it takes time to serialize the data object into a JSON string, and on the receiver, it also takes time to parse the JSON string back to the original data structure. These serialization and deserialization operations usually require more computing resources, which may lead to an increase in processing delay. Therefore, a data transmission method that can improve the transmission rate is needed, and the present invention solves this technical problem. Summary of the invention

[0004] The purpose of this application is to provide a monitoring app data transmission method based on a self-organizing network, aiming to solve the technical problems corresponding to the background technology.

[0005] In order to achieve the above purpose, the present application proposes a monitoring app data transmission method based on a self-organizing network, the monitoring app data transmission method based on a self-organizing network includes a monitoring device, and also includes the following steps:

[0006] S1. Transmit the data collected by the monitoring device to the device equipped with the monitoring app;

[0007] S2. If real-time monitoring is not required, the video frame rate is reduced to reduce the speed at which video image data is generated;

[0008] S3, using motion detection technology, when the monitoring device detects motion on the screen, it starts transmitting the video to the device equipped with the monitoring app;

[0009] S4, reducing the amount of video image data to be transmitted by using a video compression algorithm;

[0010] S5. Data is transmitted between monitoring apps in binary mode, and a private protocol combining UDP and TCP is used to receive and send data.

[0011] Furthermore, the step S2 includes the following steps:

[0012] S21. Calculate the video frame rate:

[0013]

[0014] S22, determining the time interval between each frame;

[0015] S23: If the frame rate of the video needs to be reduced, a frame discarding strategy is performed according to the video frame rate and the time interval, that is, one frame is discarded every n frames to reduce the frame rate.

[0016] Furthermore, the specific process of step S22 is as follows:

[0017] The original frame rate of the video captured by the monitoring device is expressed as

[0018] fps original

[0019] The adjusted frame rate is expressed as

[0020] fps new

[0021] Then the adjusted time interval Δt between each frame is calculated by the following formula:

[0022]

[0023] The original time interval between each frame is:

[0024]

[0025] This determines the time interval between each frame.

[0026] Furthermore, the specific process of step S23 is as follows:

[0027] When one frame is dropped every n frames, the new frame rate is expressed as:

[0028]

[0029] The frame rate is reduced in the above manner.

[0030] Furthermore, the specific process of step S3 is as follows:

[0031] S31, extracting two consecutive frames from the video stream;

[0032] S32, calculating the difference between two consecutive frames;

[0033] D(x, y) = |F t (x, y)-F t-1 (x, y)|

[0034] Among them, F t (x, y) is the pixel value at position (x, y) in the current frame, F t-1 (x, y) is the pixel value at this position in the previous frame, and D(x, y) is the difference value;

[0035] S33, setting a threshold value, when the difference between two consecutive frames exceeds the threshold value, it is considered that the picture has moved at that position;

[0036] S34, binarizing the difference matrix to mark the motion area;

[0037] S35. Create a difference frame containing only moving pixels.

[0038] Furthermore, the specific process of step S34 is expressed by the following formula:

[0039]

[0040] Among them, M(x, y) is the binarized motion matrix, θ is the threshold, where 1 indicates that the pixel has changed, and 0 indicates no change.

[0041] Furthermore, the specific process of step S35 is expressed by the following formula:

[0042]

[0043] Among them, F diff Indicates a difference frame.

[0044] Furthermore, the specific process of step S4 is expressed by the following formula:

[0045] S41, converting the image data in the video from the pixel domain to the frequency domain through discrete cosine transform, the specific formula is as follows:

[0046]

[0047] Among them, f(x, y) is the pixel value, C u，v are the transformed coefficients, M and N represent the width and height of the image, respectively, and u and v are the coordinates in the frequency domain;

[0048] S42, performing quantization operation to reduce the accuracy of the transform coefficients:

[0049]

[0050] Among them, Q u，v Represents the quantized coefficient, QF u，v is the quantization factor, which controls the strength of the compression.

[0051] Furthermore, in step S5, the process of sending the text message is as follows:

[0052] S51, using UDP protocol to send binary text messages;

[0053] S52: After receiving the message, the receiver sends a reply packet to the sender to confirm the message reception status.

[0054] Furthermore, in step S5, the process of sending the file-type multimedia message is as follows:

[0055] S53, start the TCP server first, and wait for the client to connect;

[0056] S54, using UDP protocol to send file information and server port number to the recipient;

[0057] S55. When the receiver receives the message that is a file-related message and the server port number, it starts the TCP client and waits for file transmission.

[0058] The technical effects of the present invention are as follows:

[0059] (1) This application adopts binary data transmission. Compared with data in JSON format, this solution reduces the amount of data. Compared with JSON text format, binary data is more compact. In addition, this application adopts UDP with TCP private protocol to increase the reliability and efficiency of data transmission. In addition, this application reduces the frame rate of the surveillance video, transmits video data when the captured picture moves, and compresses the image data of the video to further reduce the data required to be transmitted, thereby improving the transmission efficiency of the surveillance video data.

[0060] (2) This application reduces the frame rate so that the number of images captured in the same time is reduced, thereby reducing the speed of data generation, and further reducing the amount of data generated by video shooting, reducing the data that needs to be transmitted, thereby reducing the time of data transmission and improving data transmission efficiency;

[0061] (3) This solution can start transmitting video only when motion or changes in the picture are detected based on motion detection technology, thereby avoiding real-time data transmission, further reducing the amount of data required to be transmitted, reducing data transmission time, and improving data transmission efficiency;

[0062] (4) This solution can compress the collected video image data. Through discrete cosine transform, it can concentrate the energy of the image data on as few coefficients as possible, and then reduce the accuracy of the coefficients through quantization, thereby reducing unnecessary information and reducing the data that needs to be transmitted, further improving data transmission efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0064] Figure 1 This is the workflow diagram of this application.

[0065] Figure 2 A schematic diagram of text message sending in this application.

[0066] Figure 3 A schematic diagram of sending an audio message in this application.

[0067] Figure 4 A schematic diagram of sending a video message in this application.

[0068] Figure 5 A schematic diagram of an audio call for this application.

[0069] Figure 6 This is a schematic diagram of a video call for this application.

[0070] Figure 7 This is a schematic diagram of the Json data format.

[0071] Figure 8 A schematic diagram of the binary data format.

[0072] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0073] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0074] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0075] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features limited to "first" and "second" may explicitly or implicitly include at least one of the features. In addition, if "and / or" or "and / or" appears in the full text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or solutions that satisfy both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0076] See also Figure 1-Figure 6 The present invention proposes a monitoring app data transmission method based on a self-organizing network, the monitoring app data transmission method based on a self-organizing network includes a monitoring device, and further includes the following steps:

[0077] S1. Transmit the data collected by the monitoring device to the device equipped with the monitoring app;

[0078] S2. If real-time monitoring is not required, the video frame rate is reduced to reduce the speed at which video image data is generated;

[0079] S3, using motion detection technology, when the monitoring device detects motion on the screen, it starts transmitting the video to the device equipped with the monitoring app;

[0080] S4, data is transmitted between monitoring apps in binary mode, and the amount of video image data to be transmitted is reduced by video compression algorithm;

[0081] S5. Use a private protocol that combines UDP and TCP to receive and send data.

[0082] See also Figure 7 , Figure 8 This application transmits data in binary format, and can only transmit the field data that needs to be transmitted. Compared with the JSON text format, binary data is more compact because it avoids the key and additional punctuation marks in JSON, such as colons and quotation marks, which greatly reduces the amount of data that needs to be transmitted.

[0083] From the above content, it can be seen that this solution can reduce the amount of data by changing the data transmission method, delaying the data generation speed, avoiding real-time transmission of video data, and adopting video compression algorithm, thereby reducing the amount of data that needs to be transmitted.

[0084] Furthermore, the step S2 includes the following steps:

[0085] S21. Calculate the video frame rate:

[0086]

[0087] S22, determining the time interval between each frame;

[0088] S23: If the frame rate of the video needs to be reduced, a frame discarding strategy is performed according to the video frame rate and the time interval, that is, one frame is discarded every n frames to reduce the frame rate.

[0089] When the frame rate needs to be lowered, it can be achieved through the above method, which can reduce the number of video frames generated per second, thereby reducing the speed of data generation and thus reducing the amount of data.

[0090] In order to reduce the amount of data transmitted, in addition to binary transmission, the frame rate of the captured video can also be reduced in the above-mentioned way, which can reduce the amount of data in the video itself, thereby reducing the amount of data when the video data is subsequently transmitted.

[0091] Furthermore, the specific process of step S22 is as follows:

[0092] The original frame rate of the video captured by the monitoring device is expressed as

[0093] fps original

[0094] The adjusted frame rate is expressed as

[0095] fpsnew

[0096] Then the adjusted time interval Δt between each frame is calculated by the following formula:

[0097]

[0098] The original time interval between each frame is:

[0099]

[0100] This determines the time interval between each frame.

[0101] Through the above method, when the time interval between each frame is too large, making the video look stuck; or the interval is too small so that the data is generated faster, and you want to change the time interval between each frame, you can use the above method to adjust it.

[0102] Furthermore, the specific process of step S23 is as follows:

[0103] When one frame is dropped every n frames, the new frame rate is expressed as:

[0104]

[0105] The frame rate is reduced in the above manner.

[0106] For example, when it is selected to discard one frame out of every two frames, the time originally required to generate two frames can now only generate one frame.

[0107] Lowering the frame rate is an effective way to reduce the speed at which data is generated, but it should also be noted that lowering the frame rate will affect the continuity and detail of the video, especially in scenes that need to capture fast movements. Therefore, when adjusting the frame rate, staff need to weigh the amount of data and video quality based on actual monitoring needs.

[0108] Furthermore, the specific process of step S3 is as follows:

[0109] S31, extracting two consecutive frames from the video stream;

[0110] S32, calculating the difference between two consecutive frames;

[0111] D(x, y) = |F t (x, y)-F t-1 (x, y)|

[0112] Among them, F t (x, y) is the pixel value at position (x, y) in the current frame, F t-1 (x, y) is the pixel value at this position in the previous frame, and D(x, y) is the difference value;

[0113] S33, setting a threshold value, when the difference between two consecutive frames exceeds the threshold value, it is considered that the picture has moved at that position;

[0114] S34, binarizing the difference matrix to mark the motion area;

[0115] S35. Create a difference frame containing only moving pixels.

[0116] Video streaming is a digital signal transmission method that divides video data into a series of continuous packets or frames and transmits them in real time or near real time over the network.

[0117] Through the above method, only the changed pictures can be transmitted. For the unchanged pictures, there is no need to transmit all the captured video data in real time, thereby reducing the data transmission. By comparing the difference frames, the area where the picture moves can be identified. Because the video stream contains a large amount of data, directly processing each frame will consume a lot of computing resources, and the difference frame only contains the changed area, reducing the amount of data that needs to be processed, thereby reducing the processing time and improving the speed of data transmission.

[0118] Furthermore, the specific process of step S34 is expressed by the following formula:

[0119]

[0120] Among them, M(x, y) is the binarized motion matrix, θ is the threshold, where 1 indicates that the pixel has changed, and 0 indicates no change.

[0121] Furthermore, the specific process of step S35 is expressed by the following formula:

[0122]

[0123] Among them, F diff Indicates a difference frame.

[0124] Among them, binarization is a basic concept in image processing, which refers to converting a standard grayscale image or a color image into an image containing only two colors, usually black and white. In this process, each pixel in the image is assigned a binary value, usually 0 (representing black) or 1 (representing white), which is determined based on the threshold θ. The purpose of binarization is to simplify image analysis, make objects in the image more prominent, and facilitate operations such as shape recognition and image segmentation.

[0125] In this way, only those parts containing motion information are processed and transmitted, saving bandwidth and reducing storage requirements. This is particularly useful for applications with limited bandwidth or remote monitoring. It should be noted that the difference frame may not fully reconstruct the quality of the original video frame, especially in the case of large motion areas, but it is usually sufficient for monitoring purposes.

[0126] Furthermore, the specific process of step S4 is expressed by the following formula:

[0127] S41, converting the image data in the video from the pixel domain to the frequency domain through discrete cosine transform, the specific formula is as follows:

[0128]

[0129] Among them, f(x, y) is the pixel value, C u，v are the transformed coefficients, M and N represent the width and height of the image, respectively, and u and v are the coordinates in the frequency domain;

[0130] S42, performing quantization operation to reduce the accuracy of the transform coefficients:

[0131]

[0132] Among them, Q u，v Represents the quantized coefficient, QF u，v is the quantization factor, which controls the strength of the compression.

[0133] The purpose of discrete cosine transform (DCT) is to concentrate the energy of image data on as few coefficients as possible. In images and video signals, low-frequency components usually contain most of the energy, while high-frequency components contain details and noise. DCT transforms the image from the pixel domain to the frequency domain through transformation, so that the low-frequency components of the image (such as brightness information) are concentrated in the upper left corner of the transformation matrix, while the high-frequency components are distributed in the rest of the positions; because the human eye is more sensitive to low-frequency components and relatively insensitive to the details and noise of high-frequency components, the low-frequency coefficients after DCT can be encoded more accurately, while the high-frequency coefficients can sacrifice a certain degree of accuracy. This energy concentration characteristic makes DCT very suitable for compression, because it allows the compression algorithm to roughly encode or directly discard unimportant information (high-frequency components).

[0134] The coefficients after DCT are easy to quantize. Quantization reduces unnecessary information by reducing the precision of the coefficients. Since DCT concentrates energy on a few coefficients, quantization can mainly affect those coefficients that have little impact on image quality, thereby reducing the amount of data without significantly affecting visual quality.

[0135] Therefore, through the above method, in the process of the monitoring device transmitting image data to the monitoring app, the data required to be transmitted can be reduced and the data transmission efficiency can be improved.

[0136] Furthermore, in step S5, the process of sending the text message is as follows:

[0137] S51, using UDP protocol to send binary text messages;

[0138] S52: After receiving the message, the receiver sends a reply packet to the sender to confirm the message reception status.

[0139] Furthermore, in step S5, the process of sending the file-type multimedia message is as follows:

[0140] S53, start the TCP server first, and wait for the client to connect;

[0141] S54, using UDP protocol to send file information and server port number to the recipient;

[0142] S55. When the receiver receives the message that is a file-related message and the server port number, it starts the TCP client and waits for file transmission.

[0143] UDP (User Datagram Protocol) is a data transmission protocol on the Internet. It belongs to the transport layer protocol. For data with high real-time requirements (such as audio and video streams), UDP's low latency feature can provide a smoother experience. However, UDP does not guarantee the reliable arrival of data packets, has no confirmation mechanism, and does not guarantee the order of data packets.

[0144] TCP (Transmission Control Protocol) is a connection-oriented, reliable transport layer communication protocol. For data that needs to be transmitted reliably, TCP can ensure data integrity and order. This solution uses UDP with TCP's private protocol, which not only makes data transmission have a low latency effect, but also ensures data integrity, thereby improving the transmission efficiency and reliability of data transmission.

[0145] Therefore, through the above method, the amount of data transmitted between monitoring apps is reduced, the data transmission efficiency is improved, and the integrity of the data is guaranteed under the premise of improving the transmission efficiency.

[0146] See also Figure 2-Figure 6 ,The figure shows the message interface between monitoring apps, which can be Figure 2 To send a text message, edit the content of the good news and then manually click the send button to send it.

[0147] See also Figure 3 , Figure 4 , audio and video can be transmitted in the manner shown in the figure. The audio and video acquisition in this embodiment can use the MediaRecorder class of the Android platform to capture the microphone and camera, record to a local file (in the mobile phone storage directory), and then transmit the file completely and correctly to the other end through the UDP+TCP transmission method; MediaRecorder is an API for recording audio and video on the Android platform, which provides a simple way to capture audio and video data and encapsulate these data into a specified format.

[0148] Monitor the voice communication within the app group, use UDP multicast MulticastSocket to transmit audio data, and use opus codec to encode and decode the audio data.

[0149] The intra-group voice communication in this embodiment adopts opus codec, and the opus library is integrated into the app through JNI. The audio acquisition uses the Android AudioRecord class to record the audio, which is compressed by opus encoding and then multicasted through UDP multicast MulticastSocket. The receiving end receives the audio data through the multicast MulticastSocket, decodes it with opus, and plays the audio through the Android AudioTrack class.

[0150] opus is an open source audio encoding format; JNI (Java Native Interface) is a standard API provided by the Java platform, which allows Java code to call code written in other languages; AudioRecord is a class used to record audio in the Android framework, which allows applications to obtain raw audio data directly from audio hardware; MulticastSocket is a class used to support IP multicast in Java network programming; AudioTrack is a class used to play audio in Android.

[0151] See also Figure 5 , Figure 6 , you can make audio and video calls in the way shown in the figure. The audio and video call function in this solution integrates the Doubango open source framework and uses the SIP protocol. If you directly integrate and use the Doubango open source framework, the audio noise and delay are too large, and some configuration parameter modifications need to be made. Different Android models also need to be adapted to achieve noise reduction.

[0152] The doubango library contains APIs for parameters that affect audio noise and latency. Different parameter configurations need to be tested and adapted according to different models, such as aec (parameters related to audio echo, adjustment can reduce echo and thus reduce noise).

[0153] The above description is only an exemplary embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention and the drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A monitoring app data transmission method based on an ad hoc network, comprising a monitoring device, characterized in that: The following steps are also included: S1. Transmitting the data collected by the monitoring device to a device equipped with a monitoring app; S2. If real-time monitoring is not required, the video frame rate is reduced to reduce the speed at which video image data is generated; S3, using motion detection technology, when the monitoring device detects motion on the screen, it starts transmitting the video to the device equipped with the monitoring app; S4, reducing the amount of video image data to be transmitted by using a video compression algorithm; S5. Data is transmitted between monitoring apps in binary mode, and a private protocol combining UDP and TCP is used to receive and send data.

2. The monitoring app data transmission method based on ad hoc network according to claim 1 is characterized in that: The step S2 comprises the following steps: S21. Calculate the video frame rate: S22, determining the time interval between each frame; S23: If the frame rate of the video needs to be reduced, a frame discarding strategy is performed according to the video frame rate and the time interval, that is, one frame is discarded every n frames to reduce the frame rate.

3. The monitoring app data transmission method based on ad hoc network according to claim 2 is characterized in that: The specific process of step S22 is as follows: The original frame rate of the video captured by the monitoring device is expressed as fps original The adjusted frame rate is expressed as fps new Then the adjusted time interval Δt between each frame is calculated by the following formula: The original time interval between each frame is: This determines the time interval between each frame.

4. The monitoring app data transmission method based on ad hoc network according to claim 3 is characterized in that: The specific process of step S23 is as follows: When one frame is dropped every n frames, the new frame rate is expressed as: The frame rate is reduced in the above manner.

5. The monitoring app data transmission method based on ad hoc network according to claim 1 is characterized in that: The specific process of step S3 is as follows: S31, extracting two consecutive frames from the video stream; S32, calculating the difference between two consecutive frames; D(x,y)=|F t (x,y)-F t-1 (x,y)| Among them, F t (x, y) is the pixel value at position (x, y) in the current frame, F t-1 (x, y) is the pixel value at this position in the previous frame, and D(x, y) is the difference value; S33, setting a threshold value, when the difference between two consecutive frames exceeds the threshold value, it is considered that the picture has moved at that position; S34, binarizing the difference matrix to mark the motion area; S35. Create a difference frame containing only the moving pixels.

6. The monitoring app data transmission method based on ad hoc network according to claim 5 is characterized in that: The specific process of step S34 is expressed by the following formula: Among them, M(x, y) is the binarized motion matrix, θ is the threshold, where 1 indicates that the pixel has changed, and 0 indicates no change.

7. The monitoring app data transmission method based on ad hoc network according to claim 6 is characterized in that: The specific process of step S35 is expressed by the following formula: Among them, F diff Indicates a difference frame.

8. The monitoring app data transmission method based on ad hoc network according to claim 1 is characterized in that: The specific process of step S4 is expressed by the following formula: S41, converting the image data in the video from the pixel domain to the frequency domain through discrete cosine transform, the specific formula is as follows: Among them, f(x, y) is the pixel value, C u，v are the transformed coefficients, M and N represent the width and height of the image, respectively, and u and v are the coordinates in the frequency domain; S42, performing quantization operation to reduce the accuracy of the transform coefficients: Among them, Q u，v Represents the quantized coefficient, QF u，v is the quantization factor, which controls the strength of the compression.

9. The monitoring app data transmission method based on ad hoc network according to claim 1 is characterized in that: In step S5, the process of sending the text message is as follows: S51, using UDP protocol to send binary text messages; S52: After receiving the message, the receiver sends a reply packet to the sender to confirm the message reception status.

10. The monitoring app data transmission method based on ad hoc network according to claim 1 is characterized in that: In step S5, the process of sending a file-type multimedia message is as follows: S53, start the TCP server first, and wait for the client to connect; S54, using UDP protocol to send file information and server port number to the recipient; S55. When the receiver receives the message that is a file-related message and the server port number, it starts the TCP client and waits for file transmission.

Images