Vehicle-mounted multi-signal source image display synchronization method

Abstract

The present application relates to the field of image display technology of vehicle, especially to a kind of vehicle-mounted multi-signal source image display synchronization method, comprising: global synchronization frame containing global timestamp and logical frame number is sent by bus;First controller and second controller respectively collect and process the image of respective camera, generate local video frame;Based on the binding time information of recently received global synchronization frame, and using the preset delay compensation value to correct the bound logical frame number, so that the video frame of same exposure time has same logical frame number;First controller stores local video frame into first ring buffer, and receives the video frame of second controller and stores into second ring buffer;Compare the logical frame number of current ready frame in two buffer areas, if consistent, simultaneously take out and carry out layered synthesis display, if not consistent, fast channel waits slow channel alignment, execute exception handling after timeout.The present application realizes frame-level accurate synchronization of multi-channel video signal across controller.

Description

Technical Field

[0001] This application relates to the field of vehicle image display technology, and in particular to a method for synchronizing multi-signal source image display in a vehicle. Background Technology

[0002] Currently, with the widespread adoption of features such as autonomous driving, electronic rearview mirrors, and surround-view imaging, the number of cameras used for visual perception in vehicles has increased significantly, leading to the following problems:

[0003] Each subsystem's cameras are deployed independently, but vehicle installation space is limited. For example, the left rearview mirror position requires the simultaneous placement of five cameras: the electronic rearview mirror, the lower left and lower left rear cameras of the surround view system, and the left and rear left cameras for autonomous driving.

[0004] Considering wind resistance, the size of the camera support arm needs to be minimized, which poses a huge challenge to the size of the camera and the layout of the vehicle wiring harness.

[0005] The camera has high requirements for signal shielding, which increases the overall vehicle cost.

[0006] Considering the above factors, the industry has proposed a need for camera sharing, meaning that cameras located in the same or nearby positions, although serving different functions, can share their raw image signals. During sharing, in addition to considering information such as field of view, resolution, and frame rate, it is also required that the information from cameras connected to different controllers, used for the same function, and displayed in the same window must be synchronized. Current technology lacks an effective solution to this type of synchronization problem involving multiple sources of signals across controllers, resulting in time differences in the images displayed on the same screen, affecting user experience and human-computer trust. Summary of the Invention

[0007] The purpose of this invention is to provide a method for synchronizing the display of multiple signal sources in a vehicle, in order to solve the problem in the prior art where, when cameras serving different functions but located in the same or similar positions are used together, the multiple video signals connected to different controllers arrive at the display device at different times, resulting in asynchronous display of multiple images on the same screen, causing image tearing or object misalignment, which affects user experience and human-computer trust.

[0008] This invention provides the following solution:

[0009] A method for synchronizing multi-signal source image display in a vehicle includes:

[0010] A global synchronization frame is sent via the bus, the global synchronization frame including a global timestamp and a logical frame number;

[0011] The first controller and the second controller respectively acquire images from their respective cameras and process them to generate local video frames;

[0012] The first controller and the second controller each bind a global timestamp and a logical frame number to a generated local video frame based on the most recently received global synchronization frame, and correct the bound logical frame number based on a preset delay compensation value, so that local video frames corresponding to the same image exposure time have the same logical frame number on the first controller and the second controller.

[0013] The first controller stores its local video frames into a first circular buffer and receives local video frames from the second controller and stores them into a second circular buffer.

[0014] The first controller compares the logical frame numbers of the currently ready video frames in the first circular buffer and the second circular buffer;

[0015] In response to identical logical frame numbers, the corresponding video frames are retrieved and layered for composite display. In response to inconsistent logical frame numbers, the channel containing the video frame with the larger logical frame number is designated as the fast channel, and the channel containing the video frame with the smaller logical frame number is designated as the slow channel. The video frames in the fast channel wait for the slow channel to generate a video frame with the same logical frame number as the video frames in the fast channel, and exception handling is performed after the wait times out. In response to the absence of a ready video frame in at least one of the first and second circular buffers, the system waits for the next local video frame with the next logical frame number to become ready before re-comparing.

[0016] Furthermore, sending the global synchronization frame via the bus includes: a third controller, acting as a clock source, sending the global synchronization frame via the CAN bus at a preset period, wherein the logical frame number is a monotonically increasing count value, and the number is incremented by 1 each time a global synchronization frame is sent.

[0017] Furthermore, correcting the bound logical frame number based on a preset delay compensation value includes:

[0018] The first processing time of the first controller and the second processing time of the second controller are obtained, wherein the first processing time and the second processing time are the time from image exposure to the generation of local video frames and the completion of timestamp binding;

[0019] The processing time is based on the maximum value between the first processing time and the second processing time.

[0020] The difference between the baseline processing time and the individual processing time is used as the delay compensation value for the corresponding controller.

[0021] For controllers whose processing time is less than the baseline processing time, the equivalent exposure timestamp is obtained by subtracting the corresponding delay compensation value from the timestamp of the most recently received global synchronization frame. The binding logical frame number is determined according to the synchronization frame transmission period in which the equivalent exposure timestamp falls, so that local video frames corresponding to the same image exposure time obtain the same logical frame number on different controllers.

[0022] Furthermore, the first processing time and the second processing time are obtained by measuring with an oscilloscope during the system calibration phase, and the delay compensation value is pre-written into the corresponding controller.

[0023] Furthermore, the depth of both the first and second circular buffers is at least 2 frames; storing local video frames into the circular buffers includes: determining the writing slot by performing a modulo operation on the buffer depth according to the logical frame number, and the new frame overwriting the old frame in the slot.

[0024] Furthermore, the currently ready video frame refers to the latest video frame that has been written to and can be read in the circular buffer.

[0025] Furthermore, the process of the fast channel video frame waiting for the slow channel to generate a video frame with the same logical frame number as the fast channel video frame includes:

[0026] When the synchronization decision module in the first controller determines that the logical frame numbers are inconsistent, the timing is started from the moment when the video frame of the fast channel is ready.

[0027] If, within a preset maximum waiting time threshold, the slow channel generates a video frame with the same logical frame number as the fast channel, then both video frames are simultaneously extracted and layered for composite display.

[0028] When the timer reaches the maximum waiting time threshold, it is determined that the waiting time has expired.

[0029] Furthermore, the exception handling includes: obtaining the number of consecutive timeouts;

[0030] In response to the number of consecutive timeouts being less than a preset threshold, the most recently displayed previous frame is repeated as the current frame for output; if the previous frame does not exist or is unreadable, the current frame that has timed out is discarded and a downgrade prompt is displayed on the screen.

[0031] In response to the number of consecutive timeouts reaching the preset threshold, the current frame that has timed out is discarded, and a downgrade prompt is displayed on the screen.

[0032] Furthermore, the layered composite display includes: assigning different video sources to different layers according to a preset layer priority configuration, setting the transparency and cropping area parameters of each layer, and sequentially superimposing and compositing the final display image from the bottom layer to the top layer.

[0033] Furthermore, generating local video frames includes: decoding the raw image data captured by the camera and performing at least one of distortion correction, view transformation, or view stitching.

[0034] The above solution achieves the following beneficial technical effects: A global synchronization frame containing a global timestamp and logical frame number is transmitted via the CAN bus, enabling multiple camera signals connected to different controllers to obtain a unified time reference. Each controller binds the global timestamp and logical frame number to the generated local video frame and corrects the bound logical frame number based on a preset delay compensation value. This eliminates processing time discrepancies between channels caused by differences in hardware links, wiring harness lengths, and software architectures, ensuring that video frames corresponding to the same image exposure time are marked with the same logical frame number on different controllers. Therefore, this invention achieves precise frame-level synchronization of multiple camera signals connected to different controllers, solving the problem of time differences in images when multiple source signals are displayed simultaneously across controllers. It eliminates image tearing and object misalignment, significantly improving the driver's trust in the vehicle's electronic vision system.

[0035] In particular, by establishing a circular buffer for each video stream and having the first controller responsible for display perform real-time comparison and synchronization decisions on the logical frame numbers of the local and remote buffers, this invention immediately captures and synthesizes frames for display when synchronization is successful. If the logical frame numbers are inconsistent, the fast channel waits for the slow channel to align, and after a timeout, it performs a degradation process of either repeating the previous frame or discarding the current frame. This mechanism ensures strict synchronization of the displayed image while also considering the system's robustness and anomaly recovery capabilities, preventing complete display failure due to single-channel signal delay or frame loss, thus enhancing the system's adaptability in complex in-vehicle environments. Furthermore, this method does not rely on specific hardware; it only requires pre-setting delay compensation values ​​and buffer management logic in the controller, and can be implemented using existing CAN bus and video transmission links, resulting in low deployment costs and easy adoption in existing in-vehicle electronic architectures.

[0036] In particular, by layering and synthesizing synchronized multi-channel video frames according to preset layer priorities, this invention achieves flexible overlay of multi-source images such as surround view images, electronic rearview mirrors, and ADAS warning signs while ensuring consistency of underlying timestamps. Parameters such as the enabling, transparency, and cropping area of ​​each layer can be configured independently to meet the differentiated layout requirements of different functions, and the positions of objects in each layer remain completely consistent in dynamic scenes. More importantly, this solution solves the core synchronization obstacle of cross-functional camera reuse, allowing multiple independent cameras in the same or similar positions to be reused in different subsystems. This effectively reduces the number of cameras in the vehicle, simplifies wiring harness layout, and reduces the size and wind resistance of camera arms, providing greater flexibility and cost optimization space for vehicle design. Attached Figure Description

[0037] Figure 1 A flowchart illustrating a method for synchronizing in-vehicle multi-signal source image display according to an embodiment of the present invention is shown. Detailed Implementation

[0038] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] It should be noted that all uses of "first" and "second" in the embodiments of the present invention are for the purpose of distinguishing two different entities or different parameters with the same name. It is clear that "first" and "second" are only for the convenience of expression and should not be construed as limiting the embodiments of the present invention. Subsequent embodiments will not explain this in detail.

[0040] In this embodiment of the invention, three controllers are involved: a first controller, a second controller, and a third controller. The first controller serves as the main display control unit, connected to a display device and a first camera; it performs local video processing, synchronization determination, layered composite display, and exception handling. The second controller, connected to a second camera, performs local video processing and sends the generated local video frames to the first controller. The third controller acts as a clock source, sending global synchronization frames via a bus at a preset period.

[0041] After the system powers on, the third controller, acting as the clock source, begins periodically sending global synchronization frames to the CAN bus. A typical sending period is 20 milliseconds. The data field of this global synchronization frame contains two key pieces of information: a global timestamp, used to record the absolute running time after system power-on; and a logical frame number, a monotonically increasing count value, incremented by 1 with each global synchronization frame transmission. Through CAN bus broadcasting, all controllers connected to the CAN network can simultaneously receive the same global synchronization frame.

[0042] Reference Figure 1 The vehicle-mounted multi-signal source image display synchronization method specifically includes:

[0043] Step S10: Send a global synchronization frame via the bus. The global synchronization frame contains a global timestamp and a logical frame number.

[0044] In this embodiment of the invention, the system includes a clock synchronization master node, such as a third controller. After the system powers on, the third controller, acting as a clock source, begins periodically sending global synchronization frames to the CAN bus at fixed intervals. A typical sending period is 20 milliseconds. The data field of this global synchronization frame contains two key pieces of information: a global timestamp, used to record the absolute running time after the system powers on; and a logical frame number, a monotonically increasing count value, incremented by 1 each time a global synchronization frame is sent. Through CAN bus broadcasting, all controllers connected to the CAN network can simultaneously receive the same global synchronization frame.

[0045] In step S20, the first controller and the second controller respectively acquire images from their respective cameras and process them to generate local video frames.

[0046] In this embodiment of the invention, a first controller is connected to a first camera, and a second controller is connected to a second camera. Taking the first controller as an example, the first controller decodes the raw image data captured by the first camera to obtain single-frame image data. Subsequently, according to the requirements of the function served by the camera, the first controller performs local video processing operations such as distortion correction, view transformation, or view stitching on the single-frame image data to generate a displayable local video frame. The processing flow of the second controller is the same as that of the first controller; it decodes the raw image data captured by the second camera and performs distortion correction, view stitching, and other processing to generate a local video frame.

[0047] In step S30, the first controller and the second controller each bind the global timestamp and logical frame number to the generated local video frame based on the most recently received global synchronization frame, and correct the bound logical frame number based on the preset delay compensation value.

[0048] In this embodiment of the invention, due to differences in hardware links, wiring harness lengths, and software architectures between the first and second controllers, the time taken for the two video streams to generate their respective local video frames and complete timestamp binding differs from the same physical moment when the camera images are exposed. To ensure that images exposed at the same physical moment obtain the same logical frame number on different controllers, delay compensation needs to be introduced.

[0049] In some specific embodiments of the present invention, correcting the bound logical frame number based on a preset delay compensation value includes the following process:

[0050] The first processing time T1 of the first controller and the second processing time T2 of the second controller are obtained. Both the first and second processing times are the time elapsed from image exposure to the generation of a local video frame and the completion of timestamp binding. These time values ​​are obtained by measuring with an oscilloscope during the system calibration phase. During measurement, for the same physical exposure trigger signal, the time of the output video frame with timestamps from each controller is measured, and the delay values ​​T1 and T2 on their respective paths are calculated.

[0051] The maximum value between the first processing time T1 and the second processing time T2 is used as the baseline processing time Tmax. Assuming T2 is greater than T1, then the baseline processing time Tmax = T2.

[0052] The difference between the baseline processing time and the processing time of each controller is used as the delay compensation value for the corresponding controller. For the first controller, the delay compensation value ΔT1 = Tmax - T1; for the second controller, the delay compensation value ΔT2 = Tmax - T2 = 0. These delay compensation values ​​are pre-written into the non-volatile memory of each controller.

[0053] During daily operation, after receiving the most recent global synchronization frame, the controller subtracts its own delay compensation value from the timestamp of that synchronization frame to obtain the equivalent exposure timestamp. Then, based on the transmission period of the synchronization frame into which the equivalent exposure timestamp falls, it determines the logical frame number to be bound. For example, global synchronization frames are transmitted at a fixed period, with each transmission time corresponding to a logical frame number N. If the equivalent exposure timestamp falls between the transmission times of the synchronization frame with logical frame number N and the synchronization frame with logical frame number N+1, then the video frame is bound to logical frame number N.

[0054] Therefore, local video frames corresponding to the same image exposure time will be bound to the same logical frame number after undergoing their respective delay compensation on the first and second controllers.

[0055] In step S40, the first controller stores its local video frames into the first circular buffer and receives local video frames from the second controller and stores them into the second circular buffer.

[0056] In this embodiment of the invention, each slot in the circular buffer is provided with a status indicator to indicate whether the video frame in that slot has been written and is ready to be read. The currently ready video frame refers to the latest video frame in the circular buffer that has been written and is ready to be read.

[0057] In this embodiment of the invention, the first controller and the second controller each establish a circular buffer for the video stream they are processing. The depth of the circular buffer is at least 2 frames to ensure that the previous frame can be retained for exception handling during synchronization waiting. The circular buffer contains multiple frame slots, each slot can store a complete frame of video data and its bound logical frame number, and has a status flag to indicate whether the frame in the slot has been written and can be read. When a new video frame is generated, the slot to be written is determined by taking the modulo of its logical frame number and the buffer depth. The new frame overwrites the old frame in the slot, and the status flag is updated to ready.

[0058] After generating each local video frame and completing the logical frame number binding, the second controller immediately transmits the local video frame with the logical frame number to the first controller in real time via a high-speed video transmission link, such as LVDS or vehicular Ethernet. At the receiving end, the first controller opens a corresponding receiving circular buffer, namely the second circular buffer, for the remote video stream from the second controller, stores the received frames in it according to the same modulo rule, and records the ready status.

[0059] It should be noted that a depth of at least 2 frames is required to retain at least one old frame for repeated display during the timeout period of a synchronization cycle, while also accommodating newly arriving frames. If the preset maximum wait time threshold may cover multiple synchronization cycles, the buffer depth should be increased accordingly to ensure that old frames are not overwritten within the maximum wait time.

[0060] In step S50, the first controller compares the logical frame numbers of the currently ready video frames in the first circular buffer and the second circular buffer.

[0061] In this embodiment of the invention, the first controller is equipped with a synchronization decision module. This module continuously monitors the status flags of each slot in the first and second circular buffers, determines the latest ready video frame in each buffer as the currently ready video frame, and compares the logical frame numbers of the two.

[0062] In step S60, in response to the logical frame numbers being consistent, the corresponding video frames are retrieved and layered for composite display; in response to the logical frame numbers being inconsistent, the channel containing the video frame with the larger logical frame number is designated as the fast channel, and the channel containing the video frame with the smaller logical frame number is designated as the slow channel. The video frames in the fast channel wait for the slow channel to generate video frames with the same logical frame numbers as the video frames in the fast channel, and exception handling is performed after the waiting timeout; if at least one of the first and second circular buffers does not have a ready video frame, for example, when the system has just been powered on or after a channel has recovered from an anomaly, then synchronization decision is not performed this time, and the comparison is re-executed after the local video frame with the next logical frame number becomes ready.

[0063] In this embodiment of the invention, if the logical frame numbers of the currently ready frames in the two buffers are the same, it indicates that they correspond to the same global synchronization cycle and are images captured at the same time. At this time, the synchronization decision module determines that synchronization is successful and immediately retrieves these two frames of video data from the two circular buffers simultaneously and sends them to the display compositing module.

[0064] If the logical frame numbers of the current ready frames in the two buffers are inconsistent—for example, the current frame number in the first circular buffer is N+1, while the current frame number in the second circular buffer is N—the synchronization decision module will determine the channel with the larger logical frame number (i.e., the local channel of the first controller) as the fast channel and the channel with the smaller logical frame number (i.e., the remote channel of the second controller) as the slow channel. In this case, the video frames of the fast channel are suspended and not immediately output for display, waiting for the slow channel to generate video frames with the same logical frame number N+1 as the fast channel.

[0065] The waiting mechanism is as follows: When the synchronization decision module determines that the logical frame numbers are inconsistent, it starts timing from the moment the video frame of the fast channel is ready. If, before this timing reaches the preset maximum waiting time threshold, the slow channel generates a video frame with the same logical frame number N+1, then both video frames are simultaneously extracted and layered for composite display. The maximum waiting time threshold can be set according to system requirements, for example, 1.5 synchronization frame cycles.

[0066] If the slow channel fails to generate a corresponding frame when the maximum waiting time threshold is reached, it is considered a timeout. In this case, the synchronization decision module performs exception handling, with the exception handling strategy based on the number of consecutive timeouts. When a timeout occurs for the first time, the most recently displayed frame is prioritized as the current frame output. Since the circular buffer depth is at least 2 frames, the previous frame is retained in the circular buffer and can be retrieved and displayed repeatedly. If the previous frame does not exist or is unreadable, the timed-out current frame is discarded. When the number of consecutive timeouts reaches a preset threshold, such as 3 times, the timed-out current frame is discarded, and a downgrade prompt is displayed on the screen. This prevents severe lag in screen information caused by continuously repeating old frames, which could affect driving safety. (The last sentence is a repetition of the first two points and can be omitted.) This measure avoids severe lag in image information caused by continuous repetition of old frames, which could affect driving safety. Simultaneously, the first controller can provide corresponding downgrade prompts on the display interface.

[0067] In this embodiment of the invention, under extreme clock drift or bus congestion scenarios, the first controller and the second controller may perform delay compensation calculations based on different global synchronization frames, resulting in the two video frames having the same logical frame number but actually corresponding to different image exposure times. To address this situation, the first controller can also perform cross-validation before layered composite display: comparing the difference between the global timestamps bound to the two video frames; in response to the difference exceeding a preset timestamp deviation threshold, such as half a synchronization frame period, determining that the synchronization is pseudo-synchronization and triggering anomaly handling, such as preferentially using the video frame with the earlier timestamp as the shared frame for both channels, or outputting an alarm prompt. This cross-validation is an optional step and can be enabled in application scenarios with higher synchronization accuracy requirements.

[0068] In this embodiment of the invention, the synchronized and locked multiple video frames are sent to the display compositing module. The display compositing module has a preset layer priority configuration. In a specific example, the surround-view image stitched together can be set as the background layer at the bottom; the electronic rearview mirror image can be set as the foreground layer at the top; and the ADAS assisted driving warning signs or dynamic guide lines can be set as the topmost layer. The on / off state, transparency, and cropping area of ​​each layer can be flexibly configured according to actual functional requirements.

[0069] The compositing module superimposes the images of each layer sequentially from the bottom layer to the top layer, generating the final composite image and outputting it to the display device. Since all the source video frames on which the layers rely strictly correspond to the same logical frame number, that is, the same image exposure time, the position of the object in each layer is completely consistent when there is a moving object around the vehicle. This eliminates the problems of image tearing or object misalignment in traditional asynchronous solutions, and improves the driver's confidence in the vehicle's electronic vision system.

[0070] This invention achieves frame-level precise synchronization of multiple camera signals connected to different controllers through the above-described scheme. The CAN global synchronization frame and logical frame numbering mechanism ensures all controllers have a unified time reference. Delay compensation correction eliminates system time differences on different controller paths. A circular buffer and synchronization decision mechanism ensure that multiple images displayed simultaneously are strictly aligned at the same time. Layered display synthesis enables flexible multi-source image overlay while ensuring synchronization, enhancing the human-machine interaction experience. This scheme provides a key software foundation for cross-functional reuse of camera hardware, helping to reduce the number of cameras in the vehicle, simplify wiring harness layout, reduce wind resistance, and lower system costs.

[0071] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A method for synchronizing multi-signal source image display in a vehicle, characterized in that, include: A global synchronization frame is sent via the bus, the global synchronization frame including a global timestamp and a logical frame number; The first controller and the second controller respectively acquire images from their respective cameras and process them to generate local video frames; The first controller and the second controller each bind a global timestamp and a logical frame number to a generated local video frame based on the most recently received global synchronization frame, and correct the bound logical frame number based on a preset delay compensation value, so that local video frames corresponding to the same image exposure time have the same logical frame number on the first controller and the second controller. The first controller stores its local video frames into a first circular buffer and receives local video frames from the second controller and stores them into a second circular buffer. The first controller compares the logical frame numbers of the currently ready video frames in the first circular buffer and the second circular buffer; In response to identical logical frame numbers, the corresponding video frames are retrieved and layered for composite display. In response to inconsistent logical frame numbers, the channel containing the video frame with the larger logical frame number is designated as the fast channel, and the channel containing the video frame with the smaller logical frame number is designated as the slow channel. The video frames in the fast channel wait for the slow channel to generate a video frame with the same logical frame number as the video frames in the fast channel, and exception handling is performed after the wait times out. In response to the absence of a ready video frame in at least one of the first and second circular buffers, the system waits for the next local video frame with the next logical frame number to become ready before re-comparing.

2. The vehicle-mounted multi-signal source image display synchronization method according to claim 1, characterized in that, Sending a global synchronization frame via the bus includes: a third controller, acting as a clock source, sending the global synchronization frame via the CAN bus at a preset period. The logical frame number is a monotonically increasing count value, which is incremented by 1 each time a global synchronization frame is sent.

3. The vehicle-mounted multi-signal source image display synchronization method according to claim 1, characterized in that, The correction of the bound logical frame number based on the preset delay compensation value includes: The first processing time of the first controller and the second processing time of the second controller are obtained, wherein the first processing time and the second processing time are the time from image exposure to the generation of local video frames and the completion of timestamp binding; The processing time is based on the maximum value between the first processing time and the second processing time. The difference between the baseline processing time and the individual processing time is used as the delay compensation value for the corresponding controller. For controllers whose processing time is less than the baseline processing time, the equivalent exposure timestamp is obtained by subtracting the corresponding delay compensation value from the timestamp of the most recently received global synchronization frame. The binding logical frame number is determined according to the synchronization frame transmission period in which the equivalent exposure timestamp falls, so that local video frames corresponding to the same image exposure time obtain the same logical frame number on different controllers.

4. The vehicle-mounted multi-signal source image display synchronization method according to claim 3, characterized in that, The first processing time and the second processing time are obtained by measuring with an oscilloscope during the system calibration phase, and the delay compensation value is pre-written into the corresponding controller.

5. The vehicle-mounted multi-signal source image display synchronization method according to claim 1, characterized in that, The depth of both the first and second circular buffers is at least 2 frames; Storing local video frames into a circular buffer includes: determining the writing slot by performing a modulo operation on the buffer depth based on the logical frame number, and the new frame overwriting the old frame in that slot.

6. The vehicle-mounted multi-signal source image display synchronization method according to claim 1, characterized in that, The currently ready video frame refers to the latest video frame that has been written to and can be read in the circular buffer.

7. The vehicle-mounted multi-signal source image display synchronization method according to claim 1, characterized in that, The video frames in the fast channel that wait for the slow channel to generate video frames with the same logical frame number as the video frames in the fast channel include: When the synchronization decision module in the first controller determines that the logical frame numbers are inconsistent, the timing is started from the moment when the video frame of the fast channel is ready. If, within a preset maximum waiting time threshold, the slow channel generates a video frame with the same logical frame number as the fast channel, then both video frames are simultaneously extracted and layered for composite display. When the timer reaches the maximum waiting time threshold, it is determined that the waiting time has expired.

8. The vehicle-mounted multi-signal source image display synchronization method according to claim 7, characterized in that, The exception handling includes: obtaining the number of consecutive timeouts; In response to the number of consecutive timeouts being less than a preset threshold, the most recently displayed previous frame is repeated as the current frame for output; if the previous frame does not exist or is unreadable, the current frame that has timed out is discarded and a downgrade prompt is displayed on the screen. In response to the number of consecutive timeouts reaching the preset threshold, the current frame that has timed out is discarded, and a downgrade prompt is displayed on the screen.

9. The vehicle-mounted multi-signal source image display synchronization method according to claim 1, characterized in that, The layered composite display includes: assigning different video sources to different layers according to a preset layer priority configuration, setting the transparency and cropping area parameters of each layer, and sequentially superimposing and compositing the final display image from the bottom layer to the top layer.

10. The vehicle-mounted multi-signal source image display synchronization method according to claim 1, characterized in that, The process of generating local video frames includes: decoding the raw image data captured by the camera and performing at least one of distortion correction, view transformation, or view stitching.

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