Safety elimination integrated bus video data decoding method

Abstract

The invention discloses a safety elimination integrated bus video data decoding method. The method comprises the following steps: collecting video data of a fire scene through a video smoke detector; a video smoke detector and a bus video decoder are directly connected to a fire-fighting bus in parallel, H264 video data of a camera is packaged into an Ethernet data packet by the video smoke detector, the Ethernet data packet is sent to a PLC decoding board on the fire-fighting bus and the bus video decoder after being subjected to PLC coding, the PLC data is decoded into the Ethernet data packet, the Ethernet data packet is forwarded to a video decoding board through an Ethernet port, and the video decoding board is used for decoding the video data packet. The video decoding board analyzes the H264 video after receiving the H264 video, decodes and plays the H264 video, and outputs the H264 video to the display through the VGA / HDMI, in the video data transmission process, the video data is optimized, the video data transmission quality can be ensured, and the video data transmission quality can be ensured on the basis of a traditional fire-fighting network under the condition that an original line is not modified. And a video smoke detector and a bus video decoder are additionally arranged, so that a video monitoring function is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of fire alarm systems, and in particular relates to a method for decoding video data of a fire and safety integrated bus. Background Art

[0002] Traditional fire protection networks do not have video surveillance functions. When a fire occurs, it is necessary to go to the scene to check, which is dangerous and it is easy to miss the initial opportunity to extinguish the fire.

[0003] The Chinese patent with the publication (publication) number CN206075468U discloses a video surveillance and fire alarm linkage system, including a fire alarm subsystem, a video surveillance alarm subsystem and a linkage processing subsystem. The fire alarm subsystem is used to collect fire alarm information, the video surveillance alarm subsystem is used to collect video alarm information, and the linkage processing subsystem includes a linkage server, which is used to process fire alarm information and video alarm information. This application uses fire alarm and video surveillance intelligent analysis alarm joint alarm, and has the links of mutual verification and review of fire and video surveillance on alarm conditions, first supplementing and confirming each other, and then sending the linkage system to make corresponding linkage actions, and automatically linking to reduce false alarm rate, improve alarm accuracy, improve the degree of system automation, and improve alarm handling efficiency, so as to save costs for customers and ensure the safety of monitoring targets.

[0004] The video surveillance and fire alarm linkage system involved in the above patent achieves the purpose of collecting video data at the fire scene. However, in fact, due to the different distances between the fire scene and the fire command center, the image is easily distorted during the encoding and decoding process of the video signal, which in turn causes the video image of the fire scene to be inaccurate, affecting the firefighters' accurate judgment of the fire scene.

[0005] To this end, we propose a fire safety integrated bus video data decoding method to solve the problems existing in the existing technology, so that it can effectively transmit the video data of the fire scene and ensure the quality of video data transmission. Summary of the invention

[0006] The purpose of the present invention is to provide a method for decoding video data of an integrated fire safety bus, so as to solve the problem in the prior art proposed in the above background technology that due to the different distances between the fire scene and the fire command center, the image is easily distorted during the encoding and decoding process of the video signal, which in turn causes the video image of the fire scene to be inaccurate, affecting the firefighters' accurate judgment of the fire scene.

[0007] To achieve the above object, the present invention adopts the following technical solutions: A method for decoding video data of a fire safety integrated bus comprises the following steps: The video data of the fire scene is collected through video smoke sensors, and multiple sets of video smoke monitoring equipment are set up in the monitoring area and respectively set up in different detection areas to improve the accuracy of fire detection; Preprocess the video data of the fire scene, collect the video of the fire scene, ensure the video data is complete and of good quality, and clean the video data to delete the background, irrelevant images and animation data; Encapsulate the processed video data into Ethernet data packets, and compress the encapsulated Ethernet data packets using the JPEG compression algorithm to reduce the amount of data; Encoding the Ethernet data packet and generating a data set, wherein the Ethernet data packet encoding process adopts PLC encoding process; Transmitting the data set to a bus video decoder, the bus video decoder decodes the data set to restore the original Ethernet data packet; Parse the recovered Ethernet data packets, parse out the H264 video, and decode and play the H264 video.

[0008] Preferably, the collecting of video data of the fire scene by video smoke sensing comprises the following steps: Retrieve video smoke sensors near the fire scene and take multi-directional photos of the fire scene; Compare and analyze the video data collected from different angles, and remove the video data with repeated viewing angles; Filter the video clips that best reflect the conditions at the fire scene.

[0009] Preferably, the preprocessing of the video data of the fire scene includes: The video clips that best reflect the conditions at the fire scene will be screened for processing, including brightness balance processing, contrast enhancement processing, and video noise reduction processing.

[0010] Preferably, the brightness equalization process comprises the following steps: Decompose the collected video into pictures frame by frame; Each image corresponds to a surround view partition of the current surround view scene, and there is an overlapping area between two images corresponding to any two adjacent surround view partitions; For each of the two overlapping partitions corresponding to each overlapping region, the following operations are performed, wherein the two overlapping partitions are divided by the intersection boundary of the currently processed overlapping region, and the intersection boundary is the midline dividing the overlapping region into two symmetrical regions: Determine the preliminary gain of the currently processed overlapping partition according to the brightness mean statistical information of the two overlapping partitions; and perform the following operations for each pixel point of the currently processed overlapping partition: Determine whether the pixel point currently being processed intersects the seam boundary line; If not, adjusting the preliminary gain according to the distance from the currently processed pixel point to the intersection boundary line to obtain a reference gain, wherein the reference gain is positively correlated with the distance; And the brightness of the currently processed pixel is adjusted according to the reference gain.

[0011] Preferably, the contrast enhancement process comprises the following steps: Collect grayscale information of multiple pixels in a video image; Counting the grayscale extreme value and grayscale average value in the grayscale information of the collected video image; Determine a mapping function according to the grayscale extreme value and the grayscale average value, wherein the mapping function is a corresponding relationship between the grayscale information of each pixel before and after contrast enhancement processing; The mapping function is used to convert the grayscale information of the video image to be processed; Wherein, determining the mapping function comprises: Acquire information of video image grayscale data corresponding to the grayscale information of the collected video image, wherein the video image grayscale data is a data storage format of the grayscale information of the collected video image; Determine the linear transformation coefficient according to the function k=(AT) / (AP), wherein k is the linear change coefficient, A is the grayscale average value, P is the grayscale extreme value, and T is the extreme value of the video image grayscale data corresponding to the grayscale extreme value P; A mapping function y=A+k*(xA) is constructed by the linear transformation coefficient and the grayscale average value, wherein x is the grayscale value of the video image to be processed, and y is the mapping function value corresponding to x.

[0012] Preferably, the video noise reduction process comprises the following steps: Get the current frame image of the video; When there is a target frame image, a pixel value difference calculation is performed between a pixel point in the current frame image and a pixel point at a corresponding position in the target frame image to obtain an absolute value of the pixel value difference; Wherein, the target frame image is a frame image output after noise reduction processing of the previous frame image of the current frame image; Determine whether the absolute value is greater than a preset threshold; If the answer is yes, the pixel value of the pixel point in the current frame image for which the difference calculation is performed is used as the pixel point at the corresponding position in the updated target frame image; When the difference calculation of a preset number of pixels of the current frame image is completed, the updated target frame image is output; If the judgment is no, the target pixel value is calculated by the following formula: q=(p*(C+a)+q'*(Da)) / (C+D) Wherein, q is the target pixel value, q' is the pixel value of the pixel at the corresponding position in the target frame image, p is the pixel value of the pixel in the current frame image, a is the absolute value of the pixel difference, C and D are preset filtering parameters; C and D are positive real numbers; The pixel value of the pixel point at the corresponding position in the target frame image is updated to the target pixel value.

[0013] Preferably, encapsulating the processed video data into an Ethernet data packet comprises the following steps: Video smoke sensor extracts H264 video data captured by the camera; The video smoke sensor encapsulates the H264 video data captured by the camera into Ethernet data packets.

[0014] Preferably, the data set is transmitted to a bus video decoder, and the bus video decoder decodes the data set to restore the original Ethernet data packet, wherein: The bus video decoder is used to decode and play the video of the video smoke sensor, and the bus video decoder is composed of a video decoder board, a PLC decoder board and an aluminum alloy shell; Decoding the data set comprises the following steps: The data set after PLC encoding processing is transmitted to the bus video decoder via the fire bus; The PLC decoding board on the bus video decoder decodes the PLC data into original Ethernet data packets.

[0015] Preferably, the method of parsing the recovered Ethernet data packet, parsing out the H264 video, and decoding and playing the H264 video comprises the following steps: The PLC decoding board on the bus video decoder decodes the PLC data into Ethernet data packets and forwards them to the video decoding board through the Ethernet port; After receiving the video, the video decoding board parses the H264 video; Decode and play H264 video, and output it to the display via VGA / HDMI.

[0016] Technical effects and advantages of the present invention: Compared with the prior art, the fire safety integrated bus video data decoding method proposed by the present invention has the following advantages: The present invention connects the video smoke sensor and the bus video decoder directly in parallel on the fire bus. The video smoke sensor encapsulates the H264 video data of the camera into an Ethernet data packet, performs PLC encoding and sends it to the fire bus. The PLC decoding board on the bus video decoder decodes the PLC data into an Ethernet data packet, and forwards the data to the video decoding board through the Ethernet port. After receiving the data, the video decoding board parses the H264 video, decodes and plays the H264 video, and outputs it to the display through VGA / HDMI. In the process of video data transmission, the video data is optimized and processed to ensure the quality of video data transmission. The present invention can be installed with the video smoke sensor and the bus video decoder on the basis of the traditional fire network without modifying the original line, so as to realize the function of video monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a flow chart of the fire safety integrated bus video data decoding method in this embodiment; Figure 2 This is a schematic diagram of the networking of the video smoke sensor, bus video decoder and fire bus in this embodiment; Figure 3 is a system block diagram of a bus video decoder in this embodiment; Figure 4 : is the circuit schematic diagram of the PLC chip in this embodiment; Figure 5 is a circuit schematic diagram of the switch in this embodiment; Figure 6 This is a schematic diagram of the video decoding principle in this embodiment; Figure 7 This is a software architecture diagram of the fire safety integrated bus video data decoding method in this embodiment. Implementation

[0018] The following will be combined with the accompanying 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, rather than all the embodiments. The specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0019] The present invention discloses a method for decoding video data of a fire safety integrated bus. Figure 1 As shown, Figure 1 The flowchart of the fire safety integrated bus video data decoding method in this embodiment includes the following steps: S1. Collect video data of the fire scene through video smoke sensors, set up multiple sets of video smoke monitoring equipment in the monitoring area, and set them in different detection areas to improve the accuracy of fire detection; Exemplarily, the collecting of video data of the fire scene by video smoke sensing includes the following steps: Retrieve video smoke sensors near the fire scene and take multi-directional photos of the fire scene; Compare and analyze the video data collected from different angles, and remove the video data with repeated viewing angles; Filter the video clips that best reflect the conditions at the fire scene.

[0020] It should be noted that the video smoke sensor involved in the present embodiment is specifically a smoke sensing device, which includes a shell and a disc seat fixedly mounted on the ceiling, the shell and the disc seat are detachable and matched, a PCB board is fixed in the shell, and a smoke sensor is provided on the PCB board, the diameter of the shell is larger than the diameter of the disc seat, and a conical transition portion is formed at the connection between the shell and the disc seat, the conical transition portion is hollow, and the smoke inlet of the smoke alarm faces the conical transition portion.

[0021] A plurality of strip-shaped slots arranged in parallel are provided on the conical transition portion, and the plurality of strip-shaped slots are evenly distributed along the circumference of the conical transition portion.

[0022] A surface cover is fixed on one end of the shell body away from the disc seat.

[0023] A camera is arranged on the PCB board, and a window is opened on the surface cover, and the camera and the window are aligned with each other.

[0024] A vertical shaft and a reduction motor are fixed in the shell, a shaft sleeve is provided on the vertical shaft and the two are rotatably matched, a baffle and a sector gear extending outward are formed at the edge of the shaft sleeve, a driving gear is fixed on the output shaft of the reduction motor, the teeth of the driving gear and the edge of the sector gear are meshed with each other, and the transmission cooperation between the driving gear and the sector gear allows the reduction motor to drive the shaft sleeve to rotate forward or reverse, thereby driving the baffle to block between the camera and the window, or to move out from between the camera and the window.

[0025] A camera housing is fixed inside the shell, and the camera is arranged inside the camera housing.

[0026] The vertical height of the camera is less than or equal to the vertical height of the camera housing.

[0027] When the baffle is blocked between the camera and the window, the baffle covers the opening of the camera jacket.

[0028] The camera housing and bezel are both rounded.

[0029] S2. Preprocess the video data of the fire scene, collect the video of the fire scene, ensure that the video data is complete and of good quality, and clean the video data to delete the background, irrelevant images and animation data; Exemplarily, the preprocessing of the video data of the fire scene includes: The video clips that best reflect the conditions at the fire scene will be screened for processing, including brightness balance processing, contrast enhancement processing, and video noise reduction processing.

[0030] Specifically, the brightness balancing process includes the following steps: Decompose the collected video into pictures frame by frame; Each image corresponds to a surround view partition of the current surround view scene, and there is an overlapping area between two images corresponding to any two adjacent surround view partitions; For each of the two overlapping partitions corresponding to each overlapping region, the following operations are performed, wherein the two overlapping partitions are divided by the intersection boundary of the currently processed overlapping region, and the intersection boundary is the midline dividing the overlapping region into two symmetrical regions: Determine the preliminary gain of the currently processed overlapping partition according to the brightness mean statistical information of the two overlapping partitions; and perform the following operations for each pixel point of the currently processed overlapping partition: Determine whether the pixel point currently being processed intersects the seam boundary line; If not, adjusting the preliminary gain according to the distance from the currently processed pixel point to the intersection boundary line to obtain a reference gain, wherein the reference gain is positively correlated with the distance; And the brightness of the currently processed pixel is adjusted according to the reference gain.

[0031] Furthermore, the contrast enhancement process comprises the following steps: Collect grayscale information of multiple pixels in a video image; Counting the grayscale extreme value and grayscale average value in the grayscale information of the collected video image; Determine a mapping function according to the grayscale extreme value and the grayscale average value, wherein the mapping function is a corresponding relationship between the grayscale information of each pixel before and after contrast enhancement processing; The mapping function is used to convert the grayscale information of the video image to be processed; Wherein, determining the mapping function comprises: Acquire information of video image grayscale data corresponding to the grayscale information of the collected video image, wherein the video image grayscale data is a data storage format of the grayscale information of the collected video image; Determine the linear transformation coefficient according to the function k=(AT) / (AP), wherein k is the linear change coefficient, A is the grayscale average value, P is the grayscale extreme value, and T is the extreme value of the video image grayscale data corresponding to the grayscale extreme value P; A mapping function y=A+k*(xA) is constructed by the linear transformation coefficient and the grayscale average value, wherein x is the grayscale value of the video image to be processed, and y is the mapping function value corresponding to x.

[0032] Furthermore, the video noise reduction process includes the following steps: Get the current frame image of the video; When there is a target frame image, a pixel value difference calculation is performed between a pixel point in the current frame image and a pixel point at a corresponding position in the target frame image to obtain an absolute value of the pixel value difference; Wherein, the target frame image is a frame image output after noise reduction processing of the previous frame image of the current frame image; Determine whether the absolute value is greater than a preset threshold; If the answer is yes, the pixel value of the pixel point in the current frame image for which the difference calculation is performed is used as the pixel point at the corresponding position in the updated target frame image; When the difference calculation of a preset number of pixels of the current frame image is completed, the updated target frame image is output; If the judgment is no, the target pixel value is calculated by the following formula: q=(p*(C+a)+q'*(Da)) / (C+D) Wherein, q is the target pixel value, q' is the pixel value of the pixel at the corresponding position in the target frame image, p is the pixel value of the pixel in the current frame image, a is the absolute value of the pixel difference, C and D are preset filtering parameters; C and D are positive real numbers; The pixel value of the pixel point at the corresponding position in the target frame image is updated to the target pixel value.

[0033] S3, encapsulating the processed video data into an Ethernet data packet, and compressing the encapsulated Ethernet data packet by using a JPEG compression algorithm to reduce the amount of data; Specifically, encapsulating the processed video data into an Ethernet data packet comprises the following steps: Video smoke sensor extracts H264 video data captured by the camera; The video smoke sensor encapsulates the H264 video data captured by the camera into Ethernet data packets.

[0034] S4, encoding the Ethernet data packet and generating a data set, wherein the Ethernet data packet encoding adopts PLC encoding; Exemplarily, the Ethernet data packet is encoded and processed to generate a data set, wherein: The Ethernet data packet encoding process adopts PLC encoding process.

[0035] S5, transmitting the data set to a bus video decoder, the bus video decoder decodes the data set to restore the original Ethernet data packet; Specifically, the data set is transmitted to a bus video decoder, and the bus video decoder decodes the data set to restore the original Ethernet data packet, wherein: The bus video decoder is used to decode and play the video of the video smoke sensor. The bus video decoder is composed of a video decoder board, a PLC decoder board and an aluminum alloy shell, and the shell is treated with an aluminum alloy oxidation process; Figure 3 As shown, Figure 3 is a system block diagram of the bus video decoder in this embodiment.

[0036] Decoding the data set comprises the following steps: The data set after PLC encoding processing is transmitted to the bus video decoder via the fire bus; The PLC decoding board on the bus video decoder decodes the PLC data into original Ethernet data packets.

[0037] It should be noted that the PLC decoding board in this embodiment has two main chips: a PLC chip (MSE510CE) and a switch chip (RTL8305NB).

[0038] The PLC chip realizes the function of converting PLC signals into Ethernet signals. Figure 4 As shown, Figure 4 Schematic diagram of the circuit of the PLC chip in this embodiment.

[0039] The switch chip provides three Ethernet ports, one for connecting to the PLC chip, one for connecting to the video decoder board, and one as an external network port. Figure 5 As shown, Figure 5 FIG. 4 is a circuit diagram of the switch in this embodiment.

[0040] It should also be noted that in this embodiment, the video smoke sensor and the bus video decoder are directly connected in parallel to the fire bus. Figure 2 As shown, Figure 2 This is a schematic diagram of the networking of the video smoke sensor, bus video decoder and fire bus in this embodiment.

[0041] S6, parsing the recovered Ethernet data packet, parsing out the H264 video, and decoding and playing the H264 video; Exemplarily, the process of parsing the recovered Ethernet data packet, parsing out the H264 video, and decoding and playing the H264 video includes the following steps: The PLC decoding board on the bus video decoder decodes the PLC data into Ethernet data packets and forwards them to the video decoding board through the Ethernet port; After receiving the video, the video decoding board parses the H264 video; Decode and play H264 video, and output it to the display via VGA / HDMI.

[0042] It should be noted that the main control of the video decoder board is MC6180E, which can send and receive Ethernet data, decode H264 / H265, and output to the display through HDMI / VGA. It provides a SATA interface for connecting a hard disk to store video. Figure 6 As shown, Figure 6 FIG. 4 is a schematic diagram of the video decoding principle in this embodiment.

[0043] The following is the interface description: The bus video decoder has three LED indicators, namely POWER (indicates the power status, the green light is on when it is normal, and it is off when it is abnormal), LAN (indicates the working status of the PLC network port, the green light is on when it is normal, and it is off when it is abnormal), and CABLE (indicates the PLC bus signal status, the green light is on when it is connected, and it is off when it is not connected).

[0044] HDMI is used to connect a display with an HDMI interface to output video.

[0045] VGA is used to connect a monitor with a VGA interface to output video.

[0046] RJ45 Ethernet interface, used to expand network applications.

[0047] USB port, used to connect a mouse.

[0048] Fire bus interface, 2-PIN, non-polarity, used to connect to the fire bus.

[0049] DC12V interface, positive inside and negative outside, used to power the bus video decoder.

[0050] SATA interface, used to connect a hard disk to store video recordings.

[0051] It should also be noted that the operating system of the video decoder board is Linux-4.9, and the software adopts a multi-task software architecture to achieve the process of obtaining network packets from Ethernet, parsing H264 data, and then decoding and playing. At the same time, it provides a user operation interface to facilitate user configuration. Software architecture, such as Figure 7 As shown, Figure 7This is a software architecture diagram of the fire safety integrated bus video data decoding method in this embodiment.

[0052] GUI task: User operation interface developed based on QT to facilitate user configuration.

[0053] ONVIF task: Develop based on GSOP and implement ONVIF protocol.

[0054] RTSP task: developed based on live-555, implements RTSP protocol and pulls video stream from video smoke sensor.

[0055] Video decoding task: decode and play H264 video data and output it through VGA / HDMI interface.

[0056] Video recording task: Save H264 video stream as MP4 file. Circular storage.

[0057] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for decoding video data of a fire safety integrated bus, characterized in that: The following steps are involved: The video data of the fire scene is collected through video smoke sensors, and multiple sets of video smoke monitoring equipment are set up in the monitoring area and respectively set up in different detection areas to improve the accuracy of fire detection; Preprocess the video data of the fire scene, collect the video of the fire scene, ensure the video data is complete and of good quality, and clean the video data to delete the background, irrelevant images and animation data; Encapsulate the processed video data into Ethernet data packets, and compress the encapsulated Ethernet data packets using the JPEG compression algorithm to reduce the amount of data; Encoding the Ethernet data packet and generating a data set, wherein the Ethernet data packet encoding process adopts PLC encoding process; Transmitting the data set to a bus video decoder, the bus video decoder decodes the data set to restore the original Ethernet data packet; Parse the recovered Ethernet data packets, parse out the H264 video, and decode and play the H264 video.

2. The method for decoding video data of a fire safety integrated bus according to claim 1, characterized in that: The method of collecting video data of the fire scene by using video smoke sensors includes the following steps: Retrieve video smoke sensors near the fire scene and take multi-directional photos of the fire scene; Compare and analyze the video data collected from different angles, and remove the video data with repeated viewing angles; Filter the video clips that best reflect the conditions at the fire scene.

3. The method for decoding video data of a fire safety integrated bus according to claim 2, characterized in that: The preprocessing of the video data of the fire scene includes: The video clips that best reflect the conditions at the fire scene will be screened for processing, including brightness balance processing, contrast enhancement processing, and video noise reduction processing.

4. The method for decoding video data of a fire safety integrated bus according to claim 3, characterized in that: The brightness equalization process comprises the following steps: Decompose the collected video into pictures frame by frame; Each image corresponds to a surround view partition of the current surround view scene, and there is an overlapping area between two images corresponding to any two adjacent surround view partitions; For each of the two overlapping partitions corresponding to each overlapping region, the following operations are performed, wherein the two overlapping partitions are divided by the intersection boundary of the currently processed overlapping region, and the intersection boundary is the midline dividing the overlapping region into two symmetrical regions: Determine the preliminary gain of the currently processed overlapping partition according to the brightness mean statistical information of the two overlapping partitions; and perform the following operations for each pixel point of the currently processed overlapping partition: Determine whether the pixel point currently being processed intersects the seam boundary line; If not, adjusting the preliminary gain according to the distance from the currently processed pixel point to the intersection boundary line to obtain a reference gain, wherein the reference gain is positively correlated with the distance; And the brightness of the currently processed pixel is adjusted according to the reference gain.

5. The method for decoding video data of a fire safety integrated bus according to claim 4, characterized in that: The contrast enhancement process comprises the following steps: Collect grayscale information of multiple pixels in a video image; Counting the grayscale extreme value and grayscale average value in the grayscale information of the collected video image; Determine a mapping function according to the grayscale extreme value and the grayscale average value, wherein the mapping function is a corresponding relationship between the grayscale information of each pixel before and after contrast enhancement processing; The mapping function is used to convert the grayscale information of the video image to be processed; Wherein, determining the mapping function comprises: Acquire information of video image grayscale data corresponding to the grayscale information of the collected video image, wherein the video image grayscale data is a data storage format of the grayscale information of the collected video image; Determine the linear transformation coefficient according to the function k=(AT) / (AP), wherein k is the linear change coefficient, A is the grayscale average value, P is the grayscale extreme value, and T is the extreme value of the video image grayscale data corresponding to the grayscale extreme value P; A mapping function y=A+k*(xA) is constructed by the linear transformation coefficient and the grayscale average value, wherein x is the grayscale value of the video image to be processed, and y is the mapping function value corresponding to x.

6. The method for decoding video data of a fire safety integrated bus according to claim 5, characterized in that: The video noise reduction process comprises the following steps: Get the current frame image of the video; When there is a target frame image, a pixel value difference calculation is performed between a pixel point in the current frame image and a pixel point at a corresponding position in the target frame image to obtain an absolute value of the pixel value difference; The target frame image is a frame image output after noise reduction processing of the previous frame image of the current frame image; Determine whether the absolute value is greater than a preset threshold; If the answer is yes, the pixel value of the pixel point in the current frame image for which the difference calculation is performed is used as the pixel point at the corresponding position in the updated target frame image; When the difference calculation of a preset number of pixels of the current frame image is completed, the updated target frame image is output; If the judgment is no, the target pixel value is calculated by the following formula: q=(p*(C+a)+q'*(Da)) / (C+D) Wherein, q is the target pixel value, q' is the pixel value of the pixel at the corresponding position in the target frame image, p is the pixel value of the pixel in the current frame image, a is the absolute value of the pixel difference, C and D are preset filtering parameters; C and D are positive real numbers; The pixel value of the pixel point at the corresponding position in the target frame image is updated to the target pixel value.

7. The method for decoding video data of a fire safety integrated bus according to claim 6, characterized in that: The step of encapsulating the processed video data into an Ethernet data packet comprises the following steps: Video smoke sensor extracts H264 video data captured by the camera; The video smoke sensor encapsulates the H264 video data captured by the camera into Ethernet data packets.

8. The method for decoding video data of the fire safety integrated bus according to claim 7, characterized in that: The data set is transmitted to a bus video decoder, and the bus video decoder decodes the data set to restore the original Ethernet data packet, wherein: The bus video decoder is used to decode and play the video of the video smoke sensor, and the bus video decoder is composed of a video decoder board, a PLC decoder board and an aluminum alloy shell; Decoding the data set comprises the following steps: The data set after PLC encoding processing is transmitted to the bus video decoder via the fire bus; The PLC decoding board on the bus video decoder decodes the PLC data into original Ethernet data packets.

9. The method for decoding video data of the fire safety integrated bus according to claim 8, characterized in that: The method of parsing the recovered Ethernet data packet, parsing out the H264 video, and decoding and playing the H264 video includes the following steps: The PLC decoding board on the bus video decoder decodes the PLC data into Ethernet data packets and forwards them to the video decoding board through the Ethernet port; After receiving the video, the video decoding board parses the H264 video; Decode and play H264 video, and output it to the display via VGA / HDMI.

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