JP2009259017A - Data communication system, data processor to be used for the same, communication management device, and data communication control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To allow data communication to efficiently continue by evading the interruption of data transmission/reception as much as possible even when a processing load is increased in a data processor. <P>SOLUTION: When a task with the high processing load is performed in one of transmission units TU, the compression rate of video data to be transmitted by the transmission unit TU is reduced so as to reduce the processing load on data compression processing, thereby securing processing capacity to be required for transmitting the video data. Besides, a portion of increase in a usage band accompanying the reduction of the compression rate of the video data in the transmission unit TU which performs the task with the high processing load is compensated by: allowing another transmission unit TU to raise the compression rate of the video data in response to a request from a communication management unit 7; and narrowing the band to be used for the transfer of the video data from another transmission unit TU. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a data communication system in which a plurality of data processing devices connected to a communication bus perform data communication under management by a communication management device, a data processing device used therefor, a communication management device, and a data communication control method. Is.

Conventionally, as a countermeasure against a decrease in transfer speed due to an increase in processing load in a data processing apparatus when simultaneously transferring compressed data and non-compressed data between data processing apparatuses connected by a communication bus, Patent Document 1 below. The technique described in is known. The technique described in Patent Document 1 is a non-compressed method mainly for the purpose of real-time viewing of the priority of compressed data that is likely to be repeatedly reproduced and used among data transmitted and received between data processing devices. If the data priority is set higher and the processing load of the data processing device increases, uncompressed data is temporarily interrupted, giving priority to sending and receiving compressed data, and sending and receiving compressed data reliably. That's it.
International Publication WO2004 / 093446

  However, since the conventional technology described in Patent Document 1 is configured to allow uncompressed data to be interrupted when the processing load in the data processing device increases, the state in which the processing load has increased is long. If it continues, transmission / reception of uncompressed data will be interrupted for a long time, and the influence of the interruption of the data transmission / reception may become a big problem.

  The present invention was devised to solve the above-mentioned problems of the prior art, and even when the processing load of the data processing apparatus increases, the data transmission / reception is efficiently avoided by avoiding interruption of data transmission / reception as much as possible. It is an object of the present invention to provide a data communication system capable of continuing communication, a data processing device used therefor, a communication management device, and a data communication control method.

  The present invention compresses transmission data sent from a data processing device onto the communication bus when a processing load due to data processing other than data communication increases in any of a plurality of data processing devices connected to the communication bus. The problem is solved by reducing the rate and increasing the compression rate of the transmission data sent from the other data processing apparatus onto the communication bus.

  According to the present invention, by reducing the compression rate of the transmission data sent out on the communication bus by the data processing device having increased processing load, the transmission data is interrupted by reducing the data compression processing load in the data processing device. The amount of increase in the bandwidth used for communication accompanying this decrease in the compression rate of the transmission data can be reduced by the compression rate of the data sent from the other data processing device to the communication bus. It can be compensated by increasing. Therefore, according to the present invention, even when the processing load of the data processing apparatus increases, efficient data communication can be continued while avoiding interruption of data transmission / reception as much as possible.

  Hereinafter, as a specific embodiment of the present invention, an example in which the present invention is applied to a vehicle video system that transfers video data between a plurality of units mounted on a vehicle will be described in detail with reference to the drawings. .

  FIG. 1 is a diagram illustrating a schematic configuration of a vehicle video system according to the present embodiment. In the vehicular video system shown in FIG. 1, four units of a navigation unit 1, a first DVD unit 2, a second DVD unit 3, and an HDD unit 4, which are video data transmitting units, and a video data receiving side. These two units, the first video display unit 5 and the second video display unit 6, are connected by a serial communication bus 10 to form a network for data communication. In the network, a communication management unit 7 for managing data communication using the serial communication bus 10 between the units in the vehicular video system is provided.

  The navigation unit 1 is a unit that executes various processes for vehicle driving guidance, creates a video (navigation video) in which various information such as the vehicle position, route information, and traffic information is superimposed on a map, The video data of the navigation video is compressed and sent out on the serial communication bus 10. The compressed video data of the navigation video transmitted from the navigation unit 1 onto the serial communication bus 10 is transferred to the first video display unit 5, for example. In addition to creating navigation video and sending it as compressed video data to the communication bus 10, the navigation unit 1 can perform route search, route change, three-dimensional drawing of a map, according to operation input by a vehicle driver, etc. Execute processing such as downloading traffic information.

  The navigation unit 1 is connected with cameras 8 (for example, four on-vehicle cameras including a front camera, a back camera, a right side camera, and a left side camera) mounted on the vehicle. The navigation unit 1 also has a function of inputting video data of a camera image taken by the in-vehicle camera 8 and sending it to the serial communication bus 10 in an uncompressed state. The uncompressed video data of the camera video sent from the navigation unit 1 onto the serial communication bus 10 is transferred to the first video display unit 5, for example.

  The first DVD unit 2 and the second DVD unit 3 are units for reproducing video data recorded on a DVD (Digital Versatile Disc). The first DVD unit 2 and the second DVD unit 3 have a function of compressing the video data reproduced from the DVD and sending it onto the serial communication bus 10. The compressed video data of the DVD sent from the first DVD unit 2 and the second DVD unit 3 onto the serial communication bus 10 is transferred to the first video display unit 5 and / or the second video display unit 6. .

  The HDD unit 4 is a unit that reproduces video data recorded on the hard disk. The HDD unit 4 has a function of compressing video data reproduced from the hard disk and sending it to the serial communication bus 10. The compressed video data of the hard disk sent from the HDD unit 4 onto the serial communication bus 10 is transferred to the first video display unit 5 and / or the second video display unit 6.

  The first video display unit 5 is a video display unit installed on the front seat side of the vehicle. The navigation video generated by the navigation unit 1, the camera video shot by the in-vehicle camera 8, the first DVD unit 2 or the first video unit. 2 Selectively display a DVD video reproduced by the DVD unit 3 and a hard disk video reproduced by the HDD unit 4. The second video display unit 6 is a video display unit installed on the rear seat side of the vehicle. The second video display unit 6 is a DVD video reproduced by the first DVD unit 2 or the second DVD unit 3 or an HDD unit 4. Display images on the hard disk selectively.

  In the vehicular video system of the present embodiment in which the above units constitute a data communication network, a large number of video data flows simultaneously on the serial communication bus 10. Bands used for transferring each video data are allocated on the bus 10 to manage data communication between the units using the serial communication bus 10 so that communication failure due to insufficient bandwidth does not occur.

  Specifically, for example, as shown in FIG. 2, assuming that the bandwidth that can be used for transferring the video data of the serial communication bus 10 is 400 Mbps, a bandwidth of 104 Mbps, which is 26.0% of the entire usable bandwidth, is used. Then, the video data of the navigation video compressed to about 1/4 is transferred, and the video data of the uncompressed camera video is transferred using 55 Mbps corresponding to 13.8% of the entire usable bandwidth. Transfers video data of DVD video from the first DVD unit 2 compressed to about 1/2 using 55 Mbps corresponding to 13.8% of the entire band, and uses 55 Mbps corresponding to 13.8% of the entire usable band Then, the video data of the DVD video from the second DVD unit 3 compressed to about ½ is transferred, which is 5% which is 13.8% of the entire usable bandwidth. Use Mbps are to forward video data of the hard disk that has been compressed to about 1/2.

  By the way, among the units described above, a unit that transmits video data (hereinafter referred to as a transmission unit TU as necessary) performs other data processing in addition to the transmission of video data. When the processing load due to data processing other than the above becomes large, the processing capability that can be used for transmission of video data is limited within the limited processing capability. For example, in the navigation unit 1, a route search process is performed in response to an operation input by a vehicle driver. When the route search process is started, as shown in FIG. The processing capacity that can be used to transmit the video data is limited, and the transfer of the video data is interrupted or the transfer speed is lowered. Therefore, in the vehicular video system of the present embodiment, when the processing load due to data processing other than video data transmission increases in the transmission unit TU, for example, when the route search processing is performed in the navigation unit 1, By reducing the compression rate of the video data to be transmitted, the processing load due to the compression processing of the video data is reduced, and the processing capability used for transmitting the video data can be secured (see FIG. 3).

  Further, when the compression rate of the video data is reduced as described above in one transmission unit TU constituting the network, the data amount of the video data is increased, so that the transfer speed is reduced. In order to transfer the video data without any problem, it is necessary to widen the bandwidth used for the transfer of the video data. Here, since the band that can be used for transferring the video data of the serial communication bus 10 is limited, the band used for transferring the video data transmitted by one transmission unit TU is widened, so that another transmission unit TU is used. It is necessary to limit the bandwidth used for transferring the video data transmitted by. Therefore, in the vehicular video system of the present embodiment, when the video data compression rate is reduced in one transmission unit TU, the video data that the communication management unit 7 transmits to the other transmission unit TU. Is required to be increased, and the bandwidth used for transferring the video data transmitted by the other transmission unit TU is narrowed so that a shortage of bandwidth does not occur.

  Specifically, among the bands that can be used for transferring the video data of the serial communication bus 10, for example, as shown in FIG. 2, a band used for transferring each video data is allocated to transfer the video data. When the route search process is started in the navigation unit 1 and the processing load in the navigation unit 1 increases when the navigation unit 1 is performing, the compression rate of the navigation video is reduced from about 1/4 to about 1 as shown in FIG. The video data of the navigation video compressed to about ½ is transferred using a bandwidth of 208 Mbps, which is 52.0% of the total available bandwidth. Further, the compression rate of the DVD video by the first DVD unit 2, the compression rate of the DVD video by the second DVD unit 3, and the compression rate of the hard disk video by the HDD unit 4 are about ½ to about respectively. Each of the video data compressed to about 1/8 and compressed to about 1/8 is transferred using 14 Mbps corresponding to 3.5% of the entire usable bandwidth. Since the video data of the camera video is uncompressed video data, it is transferred using 55 Mbps corresponding to 13.8% of the entire usable bandwidth without changing the bandwidth used for the transfer.

  As described above, in the vehicular video system of the present embodiment, the transmission unit TU in which the processing load due to data processing other than the transmission of video data has increased is limited by reducing the compression rate of the video data to be transmitted. The processing load required for the data compression process is reduced in the processing capacity to secure the processing capacity necessary for transmission of the video data so that the video data can be transferred without interruption. Further, the increase in the bandwidth used on the serial communication bus 10 due to the reduction in the compression rate of the video data increases the compression rate of the video data transmitted by the other transmission unit TU, and the video data from the other transmission unit TU is increased. This is compensated by narrowing the bandwidth used for transfer so that communication failure due to insufficient bandwidth does not occur.

  Next, a specific configuration and operation of the transmission unit TU in the vehicle video system of the present embodiment as described above will be described.

  FIG. 5 is a block diagram showing an internal configuration of the transmission unit TU. As shown in FIG. 5, the transmission unit TU includes a communication control unit 11 for controlling data communication processing in the transmission unit TU, a data processing unit 12 for executing data processing other than data communication, and a data communication protocol. And a communication I / F unit 13 that performs control and the like. In addition, as a functional configuration realized in the communication control unit 11, a load determination unit 14, a load table 15, a request signal transmission unit 16, a compression rate command signal reception unit 17, a data compression unit 18, and video data transmission Part 19.

  In this transmission unit TU, data processing (tasks) other than data communication is executed by the data processing unit 12. For example, in the navigation unit 1, in addition to the above-described creation of the navigation video, tasks such as route search and route change, three-dimensional drawing of a map, and download of traffic information are executed by the data processing unit 12. The task information executed by the data processing unit 12 is given a unique identification number (task ID) for each task, and is associated with the degree of processing load when the task is executed. It is described in the load table 15 of the control unit 11. For example, in the load table 15 held by the communication control unit 11 of the navigation unit 1, as shown in FIG. 6, the contents of various tasks executed by the data processing unit 12 of the navigation unit 1 executed the task. It is described in association with the degree of processing load at the time.

  In a situation where the processing load on the data processing unit 12 is not so great as to affect the data communication, the communication control unit 11 can generate video data created by the data processing unit 12 (for example, the navigation unit 1). For example, navigation video data) is compressed by a data compression unit 18 at a specified compression rate (for example, a compression rate of 1/4), and compressed video data from the video data transmission unit 19 via the communication I / F unit 13. The data is sent out on the serial communication bus 10. In addition, when video data that is required to be transferred in real time (for example, video data of a camera video shot by the in-vehicle camera 8) is input, the communication control unit 11 does not compress the video data without compressing it. The video data is sent together with the compressed video data from the video data transmission unit 19 to the serial communication bus 10 via the communication I / F unit 13.

  Here, a case where a task with a high processing load such as route search is executed in the data processing unit 12 will be considered. In this case, the communication control unit 11 determines in the load determination unit 14 that the processing load by the data processing unit 12 is greater than or equal to the reference value. The determination of the processing load in the data processing unit 12 by the load determination unit 14 is performed using, for example, the load table 15 described above. That is, since the load table 15 describes the content of the task executed by the data processing unit 12 and the degree of the processing load when the task is executed, the load determination unit 14 The processing load in the data processing unit 12 when executing this task is obtained by referring to the load table 15 from the contents of the task that is called according to the operation input by the driver, etc., and whether or not this processing load exceeds the reference value. to decide.

  When the load determination unit 14 determines that the processing load on the data processing unit 12 exceeds the reference value, the communication control unit 11 requests the communication management device 7 to permit the data compression unit 18 to reduce the compression rate of the video data. A request signal to be generated is generated by the request signal transmission unit 16, and this request signal is transmitted to the communication management unit 7 via the serial communication bus 10. It should be noted that information indicating the degree of processing load due to a task newly executed by the transmission management unit TU is preferably added to the request signal transmitted from the transmission unit TU to the communication management unit 7. As a result, the communication management unit 7 can determine the degree of processing load on the transmission unit TU based on this request signal, and the bandwidth adjustment and compression rate calculation processing described later can be easily performed.

  Thereafter, as a response to the request signal for requesting permission to lower the compression rate of the video data, the communication management unit 7 sends a compression rate command signal designating the reduced compression rate onto the serial communication bus 10. The control unit 11 receives the compression rate command signal from the communication management unit 7 at the compression rate command signal reception unit 17. Then, the compression rate of the video data in the data compression unit 18 is reduced from the specified compression rate to the compression rate specified by the compression rate command signal (for example, in the case of the navigation unit 1, the compression rate is reduced from 1/4 to 1). Thereafter, the video data generated by the data processing unit 12 at the compression rate specified by the compression rate command signal (for example, video data of navigation video in the case of the navigation unit 1). ) And is sent as compressed video data from the video data transmission unit 19 to the serial communication bus 10 via the communication I / F unit 13.

  FIG. 7 is a flowchart showing a specific example of processing by the communication control unit 11 when a task with a high processing load as described above is executed. The processing shown in the flowchart of FIG. 7 is performed by the communication control unit 11 when it is determined that a certain task is newly executed by the data processing unit 12.

  That is, when it is determined that a new task is to be executed in the data processing unit 12, the load determination unit 14 first refers to the load table 15, and the processing load in the data processing unit 12 exceeds the reference value due to the execution of the new task. It is determined whether or not (step S101). Here, the reference value for determination is set to a value obtained by subtracting the degree of processing load necessary for data communication from the processing capability of the transmission unit TU. That is, the case where the processing load in the data processing unit 12 is equal to or greater than the reference value means the case where the processing in the data processing unit 12 affects data communication.

  If it is determined in step S101 that the processing load in the data processing unit 12 is equal to or greater than the reference value, it is then determined whether or not compressed video data is being transmitted (step S102), and compressed video data is being transmitted. If there is, a request signal for requesting permission to lower the compression rate of the video data in the data compression unit 18 is transmitted from the request signal transmission unit 16 to the communication management unit 7 (step S103). Then, the communication management unit 7 waits until a compression rate command signal designating the reduced compression rate is transmitted as a response to the request signal (step S104), and the compression rate command signal from the communication management unit 7 is compressed. When the signal is received by the signal receiving unit 17, the compression rate of the video data by the data compression unit 18 is reduced to the compression rate designated by this compression rate command signal (step S105).

  After that, while the video data is compressed and transmitted at the reduced compression rate, the end of the task with a high processing load is monitored (step S106), and when the task with the high processing load ends, the request signal transmission unit A request signal for requesting that the compression rate of the video data in the data compression unit 18 be restored to the original compression rate is transmitted from 16 to the communication management unit 7 (step S107). Then, the communication management unit 7 waits until a compression rate command signal designating the original compression rate before the reduction is transmitted as a response to the request signal (step S108), and the compression rate command signal from the communication management unit 7 is received. When the compression rate command signal receiving unit 17 receives the video data, the compression rate of the video data by the data compression unit 18 is restored to the original compression rate specified by the compression rate command signal (step S109), and a series of processing ends. To do.

  When data communication is restricted due to execution of a task with a high processing load as described above, the transmission unit TU (vehicle of the present embodiment) that also transmits uncompressed video data in addition to compressed video data. In the video system for navigation, it is desirable for the navigation unit 1) to transmit the non-compressed video data with priority over the compressed video data. This makes it possible to reliably transmit uncompressed video data that requires real-time transfer without interruption even while a task with a high processing load is being executed.

  In addition, when a plurality of video data to be transmitted as uncompressed video data are input, priority is determined for each of the plurality of uncompressed video data, and transmission of uncompressed video data having a high priority is transmitted to the compressed video data. May be prioritized, and transmission of uncompressed video data with a low priority may be interrupted. In particular, when the uncompressed video data is camera images of four in-vehicle cameras mounted on the vehicle, the camera images of the four in-vehicle cameras have different importance depending on the running state of the vehicle. It is desirable that the video data of the camera video having a high importance is transmitted with priority over the compressed video data in accordance with the traveling state, and the transmission of the video data of the camera video having a low importance is interrupted.

  Specifically, for example, as shown in FIG. 8, the camera image of the front camera 8a installed in the front of the vehicle, the camera image of the back camera 8b installed in the rear of the vehicle, and the right side of the vehicle. In the navigation unit 1 that inputs the camera image of the right side camera 8c and the camera image of the left side camera 8d installed on the left side of the vehicle, if the traveling state of the vehicle is “forward”, Since the camera image of the front camera 8a, the camera image of the right side camera 8c, and the camera image of the left side camera 8d are high in importance, and the camera image of the back camera 8b is low in importance, the front camera 8a and the right side camera 8c are low in importance. The video data of each camera video of the left side camera 8d is transmitted with priority over the compressed video data, and the back camera 8b Interrupting the transmission for the video data of the camera image. On the contrary, if the running state of the vehicle is “reverse”, the camera image of the back camera 8b, the camera image of the right side camera 8c, and the camera image of the left side camera 8d are highly important, and the camera image of the front camera 8a. Is less important, the video data of the camera images of the back camera 8b, the right side camera 8c, and the left side camera 8d is transmitted with priority over the compressed video data, and the video data of the camera video of the front camera 8a is transmitted. Interrupts transmission. Further, when the vehicle is making a “right turn”, the camera video of the left side camera 8d is also less important, so transmission of the video data of the camera video of the left side camera 8d is also interrupted. On the contrary, when the vehicle is “turning left”, since the importance of the camera video of the right side camera 8c is low, the transmission of the video data of the camera video of the right side camera 8c is also interrupted.

  The priority setting of the uncompressed video data as described above can be performed independently by the transmission unit TU that transmits the uncompressed video data. However, in the vehicular video system of the present embodiment, the uncompressed video data is not compressed. Since the communication management unit 7 manages the bandwidth used for transferring all the video data on the serial communication bus 10 including the video data, the communication management unit 7 also sets the priority of the uncompressed video data. It is desirable to do this under management. The specific method for managing data communication by the communication management unit 7 will be described later in detail.

  By the way, the processing in the communication control unit 11 of the transmission unit TU described above is processing when a task with a high processing load is executed in the data processing unit 12 of the own unit. When the communication management unit 7 requests to increase the compression rate of the video data as a task with a high processing load is executed in the unit TU, the video data in the data compression unit 18 according to the compression rate increase request. It also has a function of increasing the compression ratio. That is, when a task with a high processing load is executed in the data processing unit 12 of another transmission unit TU, a compression rate command signal specifying the increased compression rate from the communication management unit 7 is sent to the serial communication bus 10. Sent out. When the communication control unit 11 receives the compression rate command signal from the communication management unit 7 at the compression rate command signal reception unit 17, the communication control unit 11 changes the compression rate of the video data in the data compression unit 18 from the specified compression rate to the compression rate command. The compression rate specified by the signal is increased (for example, from the 1/2 compression rate to the 1/8 compression rate in the case of the first DVD unit 2), and thereafter specified by this compression rate command signal. The video data created by the data processing unit 12 (for example, video data reproduced from a DVD in the case of the first DVD unit 2) is compressed at a compression rate, and the communication I / F is sent from the video data transmission unit 19 as compressed video data. The data is sent to the serial communication bus 10 via the unit 13.

  FIG. 9 is a flowchart showing the flow of processing by the communication control unit 11 when a task with a high processing load is executed in another transmission unit TU as described above.

  As shown in the flowchart of FIG. 9, the communication control unit 11 monitors the transmission of the compression rate command signal from the communication management unit 7 (step S201), and uses the compression rate command signal from the communication management unit 7 as the compression rate. When received by the command signal receiving unit 17, the compression rate of the video data by the data compression unit 18 is increased to the compression rate specified by the compression rate command signal from the communication management unit 7 (step S202). Thereafter, while the video data is compressed and transmitted at the increased compression rate, the transmission of a new compression rate command signal from the communication management unit 7 is monitored (step S203), and the new compression rate from the communication management unit 7 is monitored. When the command signal is received by the compression rate command signal receiving unit 17, the compression rate of the video data by the data compression unit 18 is restored to the original compression rate specified by the compression rate command signal from the communication management unit 7 ( Step S204) and return to Step S201.

  Next, a specific configuration and operation of the communication management device 7 that manages data communication between the units in the vehicle video system of the present embodiment will be described.

  FIG. 10 is a block diagram showing the internal configuration of the communication management unit 7. As shown in FIG. 10, the communication management unit 7 includes a data communication management unit 21 for managing data communication of the entire vehicle video system, and a communication I / O that performs protocol control of data communication in the communication management unit 7. F section 22 is provided. In addition, as a functional configuration realized in the data communication management unit 21, a request signal reception unit 23, a use band adjustment unit 24, a compression rate management table 25, an uncompressed video data priority management table 26, and a compression rate command And a signal transmission unit 27.

  The data communication management unit 21 allocates a band to be used by each unit for transmitting video data on the serial communication bus 10 so that communication failure due to insufficient bandwidth does not occur between the units using the serial communication bus 10. Data communication is managed, and particularly when one transmission unit TU requests the communication management unit 7 to permit a reduction in the compression rate of the compressed video data when executing a task with a high processing load. By adjusting the bandwidth used for each transmission unit TU, the compression rate of the compressed video data transmitted by the other transmission units TU is increased by the increase in the bandwidth used due to the decrease in the compression rate of the compressed video data transmitted by one transmission unit TU. To compensate for the narrowing of the bandwidth used for transmission of the compressed video data, so that there is no shortage of bandwidth. It has a function.

  Specifically, when a request signal for requesting permission to reduce the compression rate of the compressed video data is transmitted from one transmission unit TU, the data communication management unit 21 of the communication management unit 7 sends a request from the transmission unit TU. The request signal receiving unit 23 receives the signal. Then, in the use band adjusting unit 24, the compression rate management table 25 and the uncompressed video data priority are set so that a shortage of bandwidth does not occur even when the transmission unit TU that has transmitted the request signal decreases the compression rate of the compressed video data. The management table 26 is used to adjust the bandwidth used for each transmission unit TU and calculate the compression rate of the compressed video data transmitted by each transmission unit TU.

  The compression rate management table 25 is a table that describes the changeable range of the compression rate of the compressed video data in each transmission unit TU. For example, as shown in FIG. 11, the compression (default) compression for each transmission unit TU. The ratio, the minimum and maximum compression ratios that can be changed, and the number of stages when the compression ratio is changed are described. The uncompressed video data priority management table 26 is a table that describes information for setting priorities of a plurality of uncompressed video data. For example, as described above, a plurality of uncompressed video data is stored in the vehicle. In the case of the camera images of the four mounted on-vehicle cameras 8a to 8d, the information as shown in FIG. 8 indicating which on-vehicle camera camera image has priority according to the traveling state of the vehicle is uncompressed video data. It is described in the priority management table 26. The used bandwidth adjustment unit 24 can recognize the range in which the bandwidth can be adjusted for each transmission unit TU by referring to the compression rate management table 25 and the uncompressed video data priority management table 26. The adjustment of the use band for each transmission unit TU and the calculation of the compression rate of the compressed video data for each transmission unit TU in accordance with the adjusted use band, the compression rate management table 25 and the uncompressed video data priority The management table 26 can be used appropriately and simply.

  Note that the compression management table 25 and the uncompressed video data priority management table 26 may be created in advance in the system design stage and stored in the data communication management unit 21 of the communication management unit 7. The management unit 7 requests each transmission unit TU to transmit information relating to data communication for each transmission unit TU, and information relating to data communication transmitted from each transmission unit TU as a response to this request is transmitted to the communication management unit 7. It is also possible to adopt a configuration in which the compression management table 25 and the non-compressed video data priority management table 26 are created by the data communication management unit 21. In this case, even if the transmission unit TU on the network is changed, the latest compression management table 25 and uncompressed video data priority management table 26 corresponding to the change of the transmission unit TU are stored in the communication management unit 7. It can be created and held at any time by the data communication manager 21.

  The data communication management unit 21 of the communication management unit 7 adjusts the use band for each transmission unit TU in the use band adjustment unit 24 and calculates the compression rate of the compressed video data transmitted by each transmission unit TU. A compression rate command signal for requesting the TU to change the compression rate is generated by the compression rate command signal transmission unit 27, and this compression rate command signal is transmitted to each transmission unit TU via the serial communication bus 10. To do.

  Here, in the compression rate command signal transmitted from the communication management unit 7 to the transmission unit TU that transmitted the request signal, information indicating that the compression rate reduction of the compressed video data in the transmission unit TU is permitted, and use And information specifying the reduced compression rate calculated by the band adjusting unit 24 is included. The transmission unit TU that has transmitted the request signal receives the compression rate command signal from the communication management unit 7 and reduces the compression rate of the compressed video data to the compression rate specified by the compression rate command signal. Further, in the compression rate command signal transmitted from the communication management unit 7 to other transmission units TU other than the transmission unit TU that transmitted the request signal, information for requesting an increase in the compression rate of the video data, and use Information specifying the compression ratio after the increase calculated by the band adjusting unit 24 is included. The transmission unit TU other than the transmission unit TU that has transmitted the request signal receives the compression rate command signal from the communication management unit 7, and the compression rate of the compressed video data is specified by the compression rate command signal. Increase to.

  Further, the data communication management unit 21 of the communication management unit 7 performs non-compression based on the non-compressed video data priority management table 26 for the transmission unit TU that transmits non-compressed video data in addition to the compressed video data. A priority setting command signal specifying the priority of the video data is generated, and this priority setting command signal is transmitted to the transmission unit TU that transmits the uncompressed video data via the serial communication bus 10. The transmission unit TU that transmits non-compressed video data in addition to the compressed video data receives the priority setting command signal from the communication management unit 7, and sets the priority of the plurality of uncompressed video data to the priority setting command. It is set according to the priority specified by the signal, and it is determined whether or not priority is given to the transmission of the compressed video data.

  FIG. 12 is a diagram showing an outline of the operation of the entire system when a task with a high processing load is executed in the navigation unit 1 in the vehicular video system of the present embodiment.

  When a task with a high processing load is executed in the navigation unit 1, first, a request signal for requesting permission to lower the compression rate of the compressed video data is transmitted from the navigation unit 1 to the communication management unit 7. When the communication management unit 7 receives the request signal from the navigation unit 1, it first acquires information indicating the running state of the vehicle (forward, backward, right turn, left turn, etc.). The information indicating the running state of the vehicle may be acquired by the communication management unit 7 by directly taking in the signal of the inhibitor switch provided in the vehicle, the signal of the steering angle sensor, etc. Since the traveling state is grasped in the navigation unit 1, the navigation unit 1 may be requested to transmit the information, and information indicating the traveling state of the vehicle may be acquired from the navigation unit 1.

  Next, the communication management unit 7 uses the compression management table 25 and the uncompressed video data priority management table 26 so that a shortage of bandwidth does not occur even when the navigation unit 1 reduces the compression rate of the compressed video data. The navigation unit 1, the first DVD unit 2, the second DVD unit 3, and the HDD unit 4 adjust the use band used for transmitting the compressed data by the transmission units TU, and adjust the use unit according to the adjusted use band. 1. The compression rate of the compressed video data transmitted by each transmission unit TU of the first DVD unit 2, the second DVD unit 3, and the HDD unit 4 is calculated. Then, the communication management unit 7 sends a compression rate command signal specifying the compression rate of the calculated compressed video data to each transmission unit TU of the navigation unit 1, the first DVD unit 2, the second DVD unit 3, and the HDD unit 4. Send.

  The compression rate command signal transmitted from the communication management unit 7 is received by each transmission unit TU of the navigation unit 1, the first DVD unit 2, the second DVD unit 3, and the HDD unit 4. Then, each transmission unit TU of the navigation unit 1, the first DVD unit 2, the second DVD unit 3, and the HDD unit 4 determines the compression rate of the compressed video data by the compression rate command signal from the communication management unit 7. After that, the compressed video data compressed at the changed compression rate is sent onto the serial communication bus 10.

  Moreover, the communication management unit 7 gives priority to the camera video of the four in-vehicle cameras 8a to 8d corresponding to the traveling state of the vehicle, with respect to the navigation unit 1 that transmits the video data of the camera video that is uncompressed video data. A priority setting command signal specifying is sent. Then, the navigation unit 1 sets the priority of the camera video of the four in-vehicle cameras 8a to 8d in response to the priority setting command signal from the communication management unit 7, and the uncompressed video of the camera video with a high priority. The data is transmitted on the serial communication bus 10 with priority over the compressed video data.

  FIG. 13 is a diagram illustrating an operation overview of the entire system when a task with a high processing load in the navigation unit 1 is completed.

  When a task with a high processing load in the navigation unit 1 is completed, first, a request signal requesting that the compression rate of the compressed video data be restored to the original compression rate is transmitted from the navigation unit 1 to the communication management unit 7. Is done. When the communication management unit 7 receives the request signal from the navigation unit 1, the communication management unit 7 refers to the compression management table 25 and sets the transmission units TU of the navigation unit 1, the first DVD unit 2, the second DVD unit 3, and the HDD unit 4. The specified (default) compression rate is acquired, and the specified (default) compression rate for each transmission unit TU of the navigation unit 1, the first DVD unit 2, the second DVD unit 3, and the HDD unit 4, that is, the original before change. A compression ratio command signal specifying the compression ratio is transmitted.

  The compression rate command signal transmitted from the communication management unit 7 is received by each transmission unit TU of the navigation unit 1, the first DVD unit 2, the second DVD unit 3, and the HDD unit 4. Then, each transmission unit TU of the navigation unit 1, the first DVD unit 2, the second DVD unit 3, and the HDD unit 4 sets the compression rate of the compressed video data to the original specified by the compression rate command signal from the communication management unit 7. Then, the compressed video data compressed at the original compression rate is sent out on the serial communication bus 10.

  In addition, the navigation unit 1 that transmits the video data of the camera video that is the uncompressed video data restores the compression rate of the compressed video data to the original compression rate, and the camera video of the four in-vehicle cameras 8a to 8d. Thereafter, all the camera images of the four in-vehicle cameras 8a to 8d are treated equally, and are sent to the serial communication bus 10 together with the compressed video data as uncompressed video data.

  As described above in detail with specific examples, in the vehicular video system according to the present embodiment, the processing load is increased by executing the task in the data processing unit 12 in any of the transmission units TU. Sometimes, the transmission unit TU reduces the compression rate of the video data transmitted on the serial communication bus 10, thereby reducing the processing load on the data compression processing within the limited processing capability and transmitting the video data. The necessary processing capacity is ensured and video data can be transferred without interruption. In addition, the increase in the bandwidth used on the serial communication bus 10 due to the decrease in the compression rate of the video data in the transmission unit TU having an increased processing load is determined by the other transmission unit TU in accordance with a request from the communication management unit 7. By increasing the compression rate and narrowing the band used for transferring video data from other transmission units TU, it is compensated to prevent communication failure due to insufficient band. Therefore, according to this vehicular video system, even when a task with a high processing load is executed by any one of the transmission units TU, it is possible to efficiently transfer the video data and continue the transfer.

  The embodiment described above is an example of application of the present invention, and the technical scope of the present invention is not intended to be limited to the contents described in the above embodiment. That is, the technical scope of the present invention is not limited to the specific technical matters disclosed in the above embodiments, but includes various modifications, changes, alternative techniques, and the like that can be easily derived from this disclosure.

  For example, the embodiment described above is an example in which the present invention is applied to a vehicular video system that transfers video data between a plurality of units mounted in a vehicle. The present invention is not limited to the system, and can be effectively applied to any data communication system in which a plurality of data processing devices having a function of transmitting compressed data are connected to one communication bus to form a network.

It is a figure which shows schematic structure of the video system for vehicles to which this invention is applied. It is a schematic diagram which shows an example of allocation of the band used for the transfer of the video data for each transmission unit. It is a figure which shows an example of the usage condition of the processing capacity in a navigation unit. It is a schematic diagram which shows an example of the result of having adjusted the zone | band used for transfer of the video data for every transmission unit according to the compression rate fall of a navigation image | video. It is a block diagram which shows the internal structure of a transmission unit. It is a figure which shows an example of the load table provided in the communication control part of the transmission unit. It is a flowchart which shows the specific example of the process by the communication control part when the task with a high processing load is performed in the data processing part of a transmission unit. It is a figure explaining the importance of the camera image | video of each vehicle-mounted camera according to the installation position of four vehicle-mounted cameras, and the driving state of a vehicle. It is a flowchart which shows the flow of a process by the communication control part when the task with a high processing load is performed in another transmission unit. It is a block diagram which shows the internal structure of a communication management unit. It is a figure which shows an example of the compression rate management table provided in the data communication management part of the communication management unit. It is a figure which shows the operation | movement outline | summary of the whole video system for vehicles when a task with a high processing load is performed in a navigation unit. It is a figure which shows the operation | movement outline | summary of the whole video system for vehicles when the task with a high processing load in a navigation unit is complete | finished.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Navigation unit 2 1st DVD unit 3 2nd DVD unit 4 HDD unit 5 1st video display unit 6 2nd video display unit 7 Communication management unit 8 (8a-8d) Car-mounted camera 10 Serial communication bus 11 Communication control part 12 Data processing part DESCRIPTION OF SYMBOLS 13 Communication I / F part 14 Load judgment part 15 Load table 16 Request signal transmission part 17 Compression rate command signal reception part 18 Data compression part 19 Video data transmission part 21 Data communication management part 22 Communication I / F part 23 Request signal reception part 24 used bandwidth adjustment unit 25 compression rate management table 26 uncompressed video data priority management table 27 compression rate command signal transmission unit TU transmission unit sensor 27 warning display unit

Claims (9)

A data communication system comprising a plurality of data processing devices connected to a communication bus and a communication management device for managing data communication by the plurality of data processing devices,
The data processing device has a function of reducing a compression rate of transmission data to be transmitted on the communication bus when a processing load due to data processing other than data communication increases.
When one of the data processing devices decreases the compression rate of the transmission data, the communication management device requests the other data processing device to increase the compression rate of the transmission data transmitted on the communication bus. A data communication system comprising the function of: A data processing device that performs data communication with other devices using a communication bus under the control of a communication management device,
Compression means for compressing transmission data to be transmitted on the communication bus;
Communication means for sending the transmission data compressed by the compression means onto the communication bus;
Processing means for performing data processing other than data communication;
Load determining means for determining the processing load by the processing means;
A compression rate reduction permission requesting unit that requests permission to lower the compression rate of transmission data to be transmitted to the communication bus when the processing load determined by the load determination unit is equal to or greater than a reference value; ,
Compression rate decrease permission acquisition means for acquiring a compression rate decrease permission from the communication management device,
Data in which the compression means lowers the compression ratio of transmission data transmitted on the communication bus when the compression ratio reduction permission acquisition means acquires the compression ratio reduction permission from the communication management device. Processing equipment. A load table in which the content of data processing performed by the processing means and the degree of processing load are described in association with each other;
The data processing apparatus according to claim 2, wherein the load determination unit determines a processing load of the processing unit based on the load table. A compression rate increase request acquisition means for acquiring a compression rate increase request from the communication management device;
When the compression rate increase request acquisition unit acquires the compression rate increase request from the communication management device, the compression unit is configured to be on the communication bus so that the compression rate specified by the compression rate increase request is obtained. 4. The data processing apparatus according to claim 2, wherein a compression rate of transmission data to be transmitted to the network is increased. Transmission data to be sent from the communication means onto the communication bus includes compressed data that is transmission data compressed by the compression means, and uncompressed data that is transmission data that is not compressed by the compression means,
5. The data processing apparatus according to claim 2, wherein the communication unit sends the non-compressed data to the communication bus in preference to the compressed data. The uncompressed data is a plurality of video data captured by a plurality of in-vehicle cameras,
The communication means is characterized in that, among the plurality of video data, video data having a high degree of importance according to a running state of a vehicle is transmitted on the communication bus with priority over the compressed data. Item 6. The data processing device according to Item 5. A communication management device for managing data communication by a plurality of data processing devices connected to a communication bus,
When one of the plurality of data processing devices requests permission to lower the compression ratio of transmission data, the bandwidth used for data communication for each data processing device is adjusted, and each data processing device is placed on the communication bus. Use band adjustment means for calculating the compression rate of transmission data to be transmitted in accordance with the adjusted use band;
The data processing device that has requested permission to reduce the compression rate specifies the compression rate calculated by the used bandwidth adjustment unit to permit the compression rate decrease, and to other data processing devices, the used bandwidth A communication management apparatus comprising: a compression rate change requesting unit that requests an increase in the compression rate of transmission data that specifies the compression rate calculated by the adjusting unit. A compression rate management table describing a range of compression rates that can be changed in each of the plurality of data processing devices;
8. The communication management according to claim 7, wherein the use band adjusting unit calculates a compression rate of transmission data transmitted from each data processing device onto the communication bus based on the compression rate management table. apparatus. A method of controlling data communication by a plurality of data processing devices connected to a communication bus,
When the processing load due to data processing other than data communication increases in any of the plurality of data processing devices, the compression rate of transmission data sent from the data processing device to the communication bus is reduced, and the others A data communication control method for increasing the compression ratio of transmission data sent from the data processing apparatus to the communication bus.

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