Systems and programs

Abstract

To provide a system more excellent than an existing system.SOLUTION: The system generates a cluster chain by allocating a predetermined number of serially numbered unused clusters in advance when recording a container file for recording generated information including picture information into an SD card, and generates a file by continuously writing the picture information into a region of a size (10MB), obtained by multiplying a cluster size (32KB) by the predetermined number (10MB / 32KB pieces).SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to, for example, a system and a program. [Background technology]

[0002] For example, drive recorders that record vehicle status information (e.g., forward footage, speed, acceleration, etc.) obtained by the vehicle onto a recording medium are becoming increasingly popular, particularly in transportation vehicles such as trucks, and commercial vehicles such as taxis and buses, and are also beginning to be installed in general vehicles.

[0003] Among drive recorders, there are those that constantly record vehicle status information while the vehicle is traveling, and those that record vehicle status information as needed for a certain period of time before and after an accident or sudden braking occurs.

[0004] The vehicle status information is recorded by such a drive recorder on a removable recording medium such as a memory card, such as an SD card, which is removable from the drive recorder. The analysis of the vehicle status information is generally performed by processing viewer application software (hereinafter referred to as a viewer app) that runs on a personal computer.

[0005] When analyzing, the recording medium is removed from the vehicle's drive recorder and inserted into a memory card reader connected to a personal computer for analysis in an office, etc. The personal computer reads the vehicle status information from the recording medium inserted into the memory card reader through processing by a viewer application, and displays the information in a visualized form on a screen (for example, Patent Document 1). This allows the vehicle status information to be confirmed and analyzed based on the information visualized on the screen. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Publication 2011-114850 Summary of the Invention [Problem to be solved by the invention]

[0007] However, conventional systems have had various problems. SUMMARY OF THE PRESENT EMBODIMENTS An object of the present invention is to provide a system, program, etc. having superior characteristics to conventional systems.

[0008] The object of the present invention is not limited to this, and the applicant intends to obtain rights for configurations that aim to obtain effects from parts of the configurations disclosed in this specification and drawings, etc., by filing a divisional application, amendment, etc. For example, this specification discloses problems in which the parts described as "can" and "is possible" in this specification are read as "is the problem." The problems are described as being independent, and the applicant intends to obtain rights for the configurations for solving each problem separately by filing a divisional application, amendment, etc. Even if the problems are implicitly understood from the description in the specification, the applicant intends to include part of the configurations described in this specification in the scope of the patent claim by amendment or divisional application. In addition, the applicant has disclosed a configuration that solves a problem that combines these independent problems, and intends to obtain rights for it. [Means for solving the problem]

[0009] (1) A system for recording the generated information on a recording medium accessible by this system, wherein when the recording medium is accessible from a personal computer, at least a portion of the information can be read by a general operating system of the personal computer, but the system records the generated information using a method different from the writing method used by the general operating system.

[0010] In this way, information recorded in the system can be read by a general operating system, and can be recorded in a method convenient for the system that differs from the writing method in the general operating system. In this way, both can be achieved. For example, in a system that differs from the writing method in the general operating system, it is possible to suppress, for example, fragmentation of the contents of the recording medium, destruction of the management area due to inaccessibility due to a sudden power outage or sudden removal of the recording medium, etc., and it is possible to reduce the number of times that the recording medium is periodically formatted, or to configure it so that it is not necessary to periodically format the recording medium.

[0011] The recording medium accessible by the system may be a recording medium connected to the system (e.g., an SSD, HDD, etc. connected via a USB cable, etc.), and in particular, the system may be configured to allow the recording medium to be removably attached (e.g., a configuration having a built-in SD card reader / writer, etc.), and the recording medium may be a recording medium attached to the system (e.g., an SD card, etc.).

[0012] The personal computer may be, for example, an IBM PC / AT compatible machine, and a typical operating system may be, for example, Microsoft Windows.

[0013] The recording medium can be accessed from a personal computer when, for example, the system has a wireless communication function (such as a WiFi network connection function) and the personal computer also has a wireless communication function that can be connected to the system, and the recording medium of the system can be accessed from the personal computer, but it is particularly preferable that a removable recording medium is removed from the system and connected to the personal computer.

[0014] In order to configure the recording medium so that at least a portion of it can be read by a general operating system of the personal computer when the recording medium is accessible from the personal computer, the recording medium should be in a format that is compatible with the standard format of the general operating system, for example, a format that is displayed in a GUI when a drive letter icon is right-clicked in Microsoft Windows Explorer and "Format" is selected. The format should preferably be at least one of FAT16, FAT32, and exFAT.

[0015] When the recording medium is inserted in a personal computer, at least a part of the recording medium can be read by a general operating system of the personal computer, but the recording method may be different from the writing method used by the general operating system. For example, the recording medium may have a partition in the same format as that used by the general operating system of the personal computer and a partition in a different format (particularly, the following (10) is preferable), or the recording medium may have a partition in the same format as that used by the general operating system of the personal computer, and the procedure for recording the partition may be different from that used by the general operating system (particularly, at least one of the following (2) to (8) is preferable). A combination of these methods may also be used.

[0016] (2) the generated information includes video data based on imaging data captured by an imaging means; The writing method in the above general operating system is such that when data is written to a file and the file size changes from 0 to 1 or more, one unused cluster is allocated at that time, and that cluster number is set in the directory entry of the file. Thereafter, whenever the file size increases and the cluster being written overflows, a new cluster is allocated and a cluster chain is formed. A method different from the writing method used in the general operating system may involve forming a cluster chain by pre-allocating a predetermined number of consecutively numbered unused clusters when generating a file including video data, and then writing data including the video data continuously into an area of ​​a size calculated by multiplying the cluster size by the predetermined number to generate the file.

[0017] In this way, even if the system repeatedly writes and erases video data based on imaging data captured by the imaging means to the recording medium, file fragmentation is less likely to occur than in the past, and files in which video data is recorded can be read using a typical operating system of a personal computer.

[0018] To make it possible to read at least a part of the disk with a general operating system, it is preferable to format the disk with a selectable cluster size when using standard formatting software for the general operating system, for example, by providing a function for formatting the recording medium with a selectable cluster size (called allocation unit size by Microsoft) in Microsoft Windows. The cluster size is 4K bytes, 8K bytes, 16K bytes, 32K bytes, and 64K bytes when the format is FAT16 or FAT32. When the format is exFAT, the cluster size is 4K bytes, 32K bytes, and 128K bytes. The predetermined number is preferably 100 or more, and more preferably 1000 or more.

[0019] Furthermore, the "size obtained by multiplying the cluster size by the predetermined number" is preferably a size in megabytes, and more preferably a size in tens of megabytes.

[0020] For example, the "size obtained by multiplying the cluster size by the predetermined number" may be one or more orders of magnitude larger than the cluster sizes selectable when formatting with standard formatting software for a typical operating system. For example, if the cluster sizes selectable when formatting with standard formatting software for a typical operating system are in kilobytes, the "size obtained by multiplying the cluster size by the predetermined number" may be in megabytes.

[0021] In this configuration, the size of one file containing this video data may be set to be larger than the "size obtained by multiplying the cluster size by the predetermined number." For example, the recording time, bit rate, etc. of the video file may be set to generate a file larger in size than the "size obtained by multiplying the cluster size by the predetermined number." Preferably, the size of one file containing this video data may be set to be several to several tens of times the "size obtained by multiplying the cluster size by the predetermined number."

[0022] In a typical operating system, when data is written to a file and the file size changes from 0 to 1 or more, one unused cluster is assigned at that time, and the cluster number is set in the directory entry of the file. After that, whenever the file size increases and the cluster being written overflows, a new cluster is assigned and a cluster chain is formed. This writing method can increase the efficiency of the recording medium when files of different sizes are repeatedly created and deleted. For example, if small and large files are mixed, the area with consecutive cluster numbers may not be secured, but it is a good method for writing files on a computer because it can be used without waste. However, in a system, video data is a large file size. Therefore, when recording video data, if the cluster size is set in megabytes, fragmentation is less likely to occur and there is less loss of efficiency. For example, with FAT, the cluster size that can be selected when formatting is in kilobytes, so when a 50MB file is recorded, it is dispersed across approximately 5,000 cluster locations, and the disadvantage is that the cluster write locations gradually become fragmented as writing and erasing is repeated. However, with this method, a specified number of consecutive clusters are secured and then video data is written to those consecutive clusters, thereby suppressing fragmentation.

[0023] The system may be configured by creating and incorporating a device driver that realizes this method in a personal computer, but it is more preferable to configure and provide a program that realizes this method in an embedded device other than a personal computer. The system is particularly preferable as a drive recorder that records images, etc. in a vehicle.

[0024] It is preferable that the system, particularly the video data, be configured to continue to be generated and recorded (called continuous recording) based on the imaging data captured by the imaging means while power is being supplied to the system.

[0025] (3) Although at least a portion of the recording medium can be read by a general operating system of the personal computer when the recording medium is inserted in the personal computer, a method different from the writing method in the general operating system is to reserve clusters in a fixed location for files that can be read by a file system adopted in the general operating system of the personal computer during the initialization process of the recording medium in the system, and to record the video data by overwriting a file that uses the previously reserved clusters to the extent that the size of the file is not exceeded, thereby recording a file containing the video data without changing the location of the clusters of the file.

[0026] In this way, it is possible to suppress fragmentation of files caused by writing video data recorded in the system to the recording medium. It is also possible to reduce or eliminate access to the file management area, and it is possible to significantly reduce the possibility of problems occurring in conventional systems, such as video files recorded on the recording medium becoming unable to be read by a personal computer due to an unexpected power outage of the system or an unexpected removal of the recording medium while updating the file management area. For example, the system may be provided with both the function (3) and the function (2), and the function of setting which recording to perform may be provided to perform the recording of the selected function.

[0027] (4) In the initialization process of the recording medium, a plurality of files using the previously secured clusters may be created in advance as fixed-length files, and the video data may be at a variable bit rate, and a recording function may be provided for setting the size of the fixed length to be larger than the size of data including the video data when recorded for the specified unit of time at a maximum bit rate of the variable bit rate, so that video data for the specified unit of time is recorded in one file of the fixed length.

[0028] In this way, the video data per unit time is recorded in a pre-created fixed-length file. Therefore, it is possible to almost certainly prevent the occurrence of file fragmentation and reduce the possibility of damage to the management area. It is preferable to repeat the process of recording the next unit time of video data in the next pre-created fixed-length file, and when recording of video data in all pre-created fixed-length files is completed, the video data is overwritten in the first fixed-length file.

[0029] The predetermined unit time is preferably in the range of 1 to 10 minutes, and particularly 1 or 5 minutes, because even if a sudden power outage or media removal occurs while the system is recording video data, the data that may be lost will be limited to this time.

[0030] (5) In the initialization process of the recording medium, a plurality of files using the pre-allocated clusters are created in advance as fixed-length files, and the video data is of variable bit rate. A function is provided for monitoring the capacity recorded in one fixed-length file and changing the fixed-length file to be recorded so that the variable bit rate video data is recorded as fully as possible in one fixed-length file.

[0031] In this way, the video time recorded in the fixed-length file of 1 is not constant, but the problem that occurs in the above method (4) where the video is not recorded in the entire fixed-length file, reducing the number of hours of video that can be recorded on the recording medium, can be solved. In a method in which a file is created in advance (a cluster in a fixed location is secured) and the cluster location is overwritten without changing, the fact that the file size is determined in advance means that a file that exceeds the file size cannot be created. Therefore, the biggest drawback of method (4) is that the amount of unused capacity in the recording medium becomes extremely large. For example, if you try to record the same amount of time as (2) or (10) described below, you will have to reduce the bit rate at which the video quality is regulated to about 2 / 3. This will result in poor quality video. However, if you use method (5), you can solve this problem.

[0032] As a configuration for recording as much as possible into the fixed-length file of 1, for example, it is preferable to buffer at least the video between key frames (the frame from the key frame to the frame before the next key frame) in the system so that the next fixed-length file starts from a key frame, and if the video between the key frames still fits into the file currently being written, it is written to the file currently being written, and if it does not fit (overflows), it is controlled so that it is recorded in the next fixed-length file. For example, the video between key frames may be between I frames, and it is preferable to configure so that the contents of the next fixed-length file do not start from a P frame or B frame, but start from an I frame. For example, both the function (5) and the function (4) may be provided, and a function for setting which recording to perform and performing the recording of the set function may be provided.

[0033] (6) The system may have a function of constantly recording the video data on the recording medium while the power is on, and in an initialization process of the recording medium, a file using the pre-allocated clusters may be created in advance as a single very large file, and the video data to be constantly recorded may be recorded in the very large file. In this way, the process can be simplified and the possibility of fragmentation can be reduced more than before.

[0034] For example, the device may be provided with at least two of the functions (4) to (6), and may have a function of setting which recording to perform and recording the set recording.

[0035] A very large file may be, for example, a file that is equal to or smaller than the capacity of the recording medium and has the maximum capacity of the file system that stores the file. Alternatively, a very large file may be, for example, a file that has a capacity equal to or larger than half the capacity of the recording medium, and in particular, the size of this file may be equal to or larger than half the capacity of the recording medium (and, for example, equal to or smaller than the capacity of the recording medium). It is also preferable to have a function that allows the size to be set within this range.

[0036] (7) It is preferable that a file using the pre-allocated clusters is generated as an invisible file in the operating system of the personal computer during initialization processing of the recording medium, and that the file to be written is made visible when writing the video data.

[0037] In this way, when the recording medium is read by a personal computer immediately after the initialization process of the recording medium is completed, a file that uses the previously secured cluster and has no video data recorded therein will not be seen.

[0038] (8) The file using the pre-allocated clusters may have a function of generating a file capable of playing video on the operating system of the personal computer during initialization of the recording medium.

[0039] In this way, the image can be viewed by playing the file that is visible when the recording medium is read out on a personal computer immediately after the initialization process of the recording medium is completed. The image data of the file capable of playing this image may be an image that continues to display a specific screen when played back, for example, an image completely covered with a specific color (for example, an image of a completely black screen), an image that continues to display a character string such as "This is an unrecorded file," or a file containing a specific image that has been recorded in advance inside the system may be generated by copying it. For example, both the function (8) and the function (7) may be provided, and a function for setting which recording to perform and performing the recording of the set function may be provided.

[0040] (9) It is preferable that the file including the video data has a function for generating the file in a file format that can be played on a general operating system of the personal computer.

[0041] In this way, the video file recorded on the recording medium can be played back on a general operating system of the personal computer. It is particularly preferable to have the configuration of (8). In particular, in the configurations of (4) to (6), it is also preferable that the file created in the initialization process is generated in a file format that can be played back on the general operating system of the personal computer.

[0042] The above format formats (2) to (9) may be the format formats adopted in the operating system of the personal computer, and in the initialization process, the format may be used in that format, and then the initialization process described in each of items (2) to (9) may be performed.

[0043] (10) The generated information may include video data based on imaging data captured by an imaging means, and the recording medium may be configured so that at least a portion of the video data can be read by a general operating system of the personal computer when the recording medium is attached to the personal computer. The recording medium may be provided with a partition having the same format as that used by the general operating system of the personal computer, and the recording medium may be provided with a function for writing to the partition. The recording medium may be provided with a partition having a different format than that used by the general operating system of the personal computer, as a method for writing to the partition in the general operating system, and the recording medium may be provided with a function for writing the video data to the partition in a sequential manner without writing an index of the video data to a management area.

[0044] In this way, the concept of fragmentation disappears. Also, the image data cannot be viewed using the standard functions of a general operating system of a personal computer. Therefore, the security element of is high.

[0045] Also, for example, in functions (2) through (9), if the recording medium is removed from the system while the management area is being written, depending on the timing, all of the contents of the recording medium may be lost. This does not happen with method (10). It is advisable to configure functions (2) through (9) so that the management area is not touched when recording video data, but there are cases where it is difficult to configure all of them in this way. In such cases, method (10) is recommended.

[0046] In the configuration of (10), a partition having the same format as that used by a general operating system of the personal computer on the recording medium may be provided with a function for recording at least one of the video data of (2) to (9) in addition to the video data of (10). In this way, even if any of the partitions is destroyed, the video data can be read and played back from the undestroyed partition.

[0047] In the method (10), since the video data is variable length, it is very difficult to find the beginning of a video frame. Therefore, it is a good idea to attach chain data to each frame so that it is possible to search between frames. It is a good idea to have a system in which each frame has a directory entry, as in FAT. The disadvantage is that it is not visible in a file search application such as Explorer in a general operating system of a personal computer, so a dedicated application is required. For example, when the recording medium is an SD card, writing to a continuous area is faster when accessing the SD card, but writing to discontinuous areas reduces the writing speed dramatically. However, if configured as in (10), this can be prevented, and for example, simultaneous writing of a total of four streams can be achieved, for example, for two cameras / continuous recording and events separately. Also, in a communication-type system, writing eight streams by adding dirty video (video with low capacity) is relatively easy compared to other recording methods.

[0048] (11) It is preferable that the video data is provided with a function of adding first information for going back a predetermined time in the past without using a management area, and second information for going back a predetermined number of frames in the past without using a management area, and cueing the video based on the first information and the second information. (12) It is preferable that the function of the system described in any one of (1) to (12) is realized by a computer.

[0049] (13) It is preferable to provide a driver program for the general operating system of a personal computer to enable a computer to realize a function that enables video data of a partition in a format different from the format used by the general operating system of the personal computer, which video data is recorded by the system described in (10) above, to be referenced from the general operating system of the personal computer.

[0050] The "personal computer" described in (1) to (13) above may be replaced with a "smartphone." Also, the "personal computer" described in (1) to (13) above may be replaced with a "tablet." In these cases, the general operating system may be Android.

[0051] The inventions shown in (1) to (11) above can be arbitrarily combined. For example, at least a part of the configuration of at least one of the inventions after (2) may be added to all or a part of the configuration of the invention shown in (1). In particular, it is preferable to add at least a part of the configuration of at least one of the inventions after (2) to the invention shown in (1). In addition, any configuration may be extracted from the inventions shown in (1) to (11) and the extracted configurations may be combined. The applicant of this application intends to obtain rights to the inventions including these configurations. In addition, even if there is a description such as "in the case of" or "when", it is not intended to describe the configuration as being limited to that case or time. These are examples of better configurations, and the applicant intends to obtain rights to configurations other than these cases or times. In addition, the parts described in order are not limited to this order. Configurations in which some parts have been deleted or the order has been changed are also disclosed, and the applicant intends to obtain rights. Effect of the Invention

[0052] According to the present invention, it is possible to provide a system etc. that is superior to conventional systems. For example, it is possible to prevent fragmentation of the contents of the recording medium, or destruction of the management area due to inaccessibility caused by sudden power outages or sudden removal of the recording medium, thereby reducing the number of times that recording media need to be formatted periodically, or providing a system that does not require periodic formatting of recording media.

[0053] The effects of the invention of this application are not limited to this, and effects achieved from the configuration disclosed in the specification and drawings are also disclosed, and the applicant intends to obtain rights to the configuration achieving said effects through divisional applications, amendments, etc. For example, in this specification, statements such as "can" and "is possible" are statements that clearly indicate the effects achieved, and there are also parts that show effects even without statements such as "can" and "is possible." Furthermore, there are effects that can be understood from the configuration even without such statements. [Brief description of the drawings]

[0054] [Figure 1] FIG. 2 is an explanatory diagram for explaining the transfer of an SD card between a drive recorder and a personal computer. [Diagram 2] FIG. 2 is an explanatory diagram illustrating an example of installation of a drive recorder in a vehicle. [Diagram 3] FIG. 2 is a block diagram illustrating an example of a schematic electrical configuration of a drive recorder. [Figure 4] FIG. 2 is a block diagram illustrating an example of a schematic electrical configuration of a personal computer and devices connected to the personal computer. [Diagram 5] FIG. 13 is a diagram showing an example of a display on a screen when viewer software is executed on a personal computer. [Figure 6] FIG. 13 is a diagram showing an example of a format selection screen displayed on the drive recorder. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0055] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the embodiment shown below is one embodiment of the present invention, and the contents of the present invention should not be interpreted as being limited based on the following description. Hereinafter, as an embodiment of the present invention, the present system will be described based on an example in which the system is realized by processing a program executed by a drive recorder installed in a vehicle.

[0056] As shown in Fig. 1, the drive recorder 1 of this embodiment has a function of compressing the image data captured by the drive recorder 1 to generate video data, and recording the compressed video data on an SD card, which is an example of a recording medium. When the engine of the vehicle is turned off and the drive recorder is powered off, the SD card is removed from the drive recorder 1 and attached to an SD card reader / writer 36 connected to a personal computer 35 installed in an office or the like, the drive recorder 1 has a function of playing and displaying the recorded video data on the screen of a viewer software shown in Fig. 5 executed by the personal computer 35. The SD card has a capacity of 32 GB. The personal computer 35 runs Microsoft Windows 10 as its operating system.

[0057] As shown in Fig. 2, the drive recorder 1 is fixed by attaching one side of a mounting member such as double-sided tape to a position on the passenger side adjacent to the rearview mirror 4 at the upper part of the vehicle's windshield 3 near the center in the left-right direction, and attaching the other side to the windshield. The drive recorder 1 is fixed with the camera lens facing in a direction to record the image in front of the vehicle. The drive recorder 1 is connected to a cigarette lighter socket 5 and a power cable 6, and is supplied with power from the vehicle when the vehicle's accessory power is on.

[0058] Fig. 3 is a diagram showing a schematic electrical configuration of the drive recorder 1. As shown in Fig. 3, the drive recorder 1 includes a controller MC, a CCD camera 13, an interface 33, a GPS receiver 24, a display unit 25 with a touch panel, an SD card reader 31, an acceleration sensor 15, a database 32, etc. The interface 33, which is connected to the CCD camera 13 and converts a video signal from the CCD camera 13 into a digital signal that can be input to the controller MC, the acceleration sensor 15, the GPS receiver 24, the display unit 25, the SD card reader 31, and the database 32 are each connected to the controller MC.

[0059] The controller MC is composed of a microcomputer having a known CPU, memories such as ROM and RAM, a timer, other peripheral circuits, etc. The ROM of the controller MC stores various programs such as a card initialization processing program for performing initialization processing to make the SD card in a state in which video data can be written, a recording processing program for storing generated information including GPS information including position information received by the GPS receiver 24, acceleration information detected by the acceleration sensor 15, and video information captured by the CCD camera 13, programs for performing various processes described below, and a real-time OS (Operation System), and the controller MC executes these programs to realize various functions. The controller MC executes a recording process program to perform a recording process for recording the generated information in one of eight formats, which will be described later.

[0060] The GPS receiver 24 detects the position information of the vehicle at the current time based on an instruction from the controller MC. In this embodiment, the detection timing is every second. The controller MC acquires GPS information including the position information every second in the recording process. The position information includes the time, the position, speed, latitude, longitude, altitude, etc. of the vehicle, which are obtained based on signals from GPS satellites.

[0061] The acceleration sensor 15 is a three-axis type sensor that detects the acceleration and tilt in each of the three axes (X, Y, Z) and constantly outputs the detected values ​​to the controller MC. During the recording process, the controller MC generates acceleration information by associating the three-axis acceleration information with time information every 10 ms.

[0062] The SD card reader 31 reads data from an SD card inserted through the insertion slot 18 or updates the data on the SD card under the control of the controller MC. The database 32 is a non-volatile memory (for example, an EEPROM) attached externally to the controller MC.

[0063] The CCD camera 13 constantly outputs captured image information to the controller MC via an interface unit 33 that converts the captured image information into digital form. In the recording process, the controller MC associates the captured image information input via the interface unit 33 with time, compresses it, and generates video information.

[0064] The controller MC performs an SD card installation check process immediately after power-on or when it detects that the SD card has been removed during recording processing. The SD card installation check process checks whether or not an SD card is installed in the SD card reader / writer 31, and if the installation of the SD card is detected, it proceeds to an SD card format confirmation process, and if the installation of the SD card is not detected, it displays the text "Please insert an SD card" on the display unit 25 and waits for the SD card to be installed, and if the installation of the SD card is detected, it erases this display and proceeds to an SD card format confirmation process.

[0065] The SD card format confirmation process reads each sector of the SD card, checks the partition and format logical structure, and determines which of the eight formats described below the card is in, and passes the resulting format type to the recording process to start the recording process. The recording process records to the SD card according to the passed format type structure. If the card does not fall into any of the eight formats, it moves to the card initialization process.

[0066] In the card initialization process, the display unit 25 displays a video data recording format screen shown in FIG. 6. The video data recording format screen is a screen for selecting one of eight formats and inputting an instruction to initialize the card. This video data recording format screen has eight lines of character strings arranged vertically indicating the formatting method, radio buttons to the left of the character strings in each line, and a "Cancel" button and an "Initialize" button at the bottom. When the "Initialize" button is touched, the initialization process is performed using the formatting method indicated by the character string in the line selected by the radio button, and then the selected format type is stored in the RAM in the controller MC and the process proceeds to recording process. When the "Cancel" button is touched, the process proceeds again to the SD card format confirmation process.

[0067] As shown in Fig. 6, the eight formatting methods are, from top to bottom, "Allocate a certain number of unused clusters with consecutive numbers in advance," "Record video data of a certain unit time in one fixed-length file (visible at initialization)," "Record video data of a certain unit time in one fixed-length file (invisible at initialization)," "Record variable bit rate video data as full as possible in one fixed-length file (visible at initialization)," "Record variable bit rate video data as full as possible in one fixed-length file (invisible at initialization)," "Record video data to be recorded continuously in one very large file (visible at initialization)," "Record video data to be recorded continuously in one very large file (invisible at initialization)," and "Record in a unique format." The processing for each case is explained below in (1) to (8). (1) In the case of "pre-allocating a certain number of consecutive unused clusters in the cluster chain"

[0068] When the controller MC detects that the "Initialize" button has been touched while "Pre-allocate a certain number of consecutive unused clusters in the cluster chain" is selected, it performs a normal FAT32 format in which the entire SD card is treated as one partition and that partition is formatted in FAT32 format, and then moves on to the recording process. The cluster size during this formatting is the same as Windows 10: 4KB if the detected capacity of the SD card is between 512MB and 8,191MB, 8KB if it is between 8,192MB and 16,383MB, 16KB if it is between 16,384MB and 32,767MB, and 32KB if it is 32,768MB or more. In this recording process, if it is determined that the type of format stored in the RAM is "pre-allocating a predetermined number of consecutive unused clusters in a cluster chain", the imaging information acquired from the CCD camera 13 for each frame is compressed with a predetermined codec (e.g., H.254, etc.) to generate frame information by adding GPS information and acceleration information in text format as subtitle data to the video information, and write 60 seconds of frame information as one container file (e.g., AVI container). The size of this container file is generally less than 70 MB. When writing this file, the writing method of Windows 10 in the personal computer 35 is a writing method in which when data is written to a file and the file size changes from 0 to 1 or more, one unused cluster is assigned at that time, the cluster number is set in the directory entry of the file, and thereafter, whenever the file size increases and the cluster being written overflows, a new cluster is assigned to form a cluster chain, but the drive recorder 35 writes using a method different from the writing method in Windows 10 running on the personal computer 35.This different method generates a cluster chain by allocating a predetermined number of consecutive unused clusters in advance when recording a container file that records generated information including video information in an SD card, and writes the video information continuously in an area of ​​a size (10MB in this embodiment) that is the cluster size (32KB in this embodiment) multiplied by this predetermined number (10MB / 32KB in this embodiment) to generate a file.Then, the next 10MB is secured and written in the same way, and the process is repeated to write the container file onto the FAT32 file system.

[0069] Specifically, when a new container file is generated in an SD card, a range in which the predetermined number of consecutively numbered clusters can be secured is searched for on the FAT (file allocation table) formatted with FAT32, and a cluster chain is generated in this range (the first cluster stores the next cluster number, the next cluster stores the cluster number, and so on). The first cluster number is then recorded in a directory entry that records the file name, etc., of the container file. After writing out 10 MB of the capacity of the cluster group corresponding to this cluster chain, a new 10 MB cluster chain is similarly generated, and the last cluster is chained to the beginning of the chain, and one minute's worth of container file (less than about 70 MB in this embodiment) is written out and the file is closed. Each 10 MB unit is treated as one huge virtual cluster, so to speak, and a container file of just under 70 MB containing one minute's worth of video information can be stored in seven virtual clusters.

[0070] According to this method, even if the drive recorder 1 repeatedly writes and erases generated information, including video information based on image information captured by the CCD camera 13, to the SD card, file fragmentation is less likely to occur than in the past, and the file can be read using Windows 10 on the personal computer 35.

[0071] In the writing method in Windows 10, when data is written to a file and the file size changes from 0 to 1 or more, one unused cluster at that time is assigned, and the cluster number is set in the directory entry of the file. After that, whenever the file size increases and the cluster being written overflows, a new cluster is assigned and a cluster chain is formed. This writing method can increase the usage efficiency of the recording medium when files of different sizes are repeatedly created and deleted. For example, when small and large files are mixed, the area with consecutive cluster numbers is not necessarily secured, but it can be used without waste, so it is a good method for writing files to a computer. However, in the drive recorder 1, the container file that records the generated information including the video information is a large file size. Therefore, in order to record video information, if the cluster size is set in megabytes, fragmentation is less likely to occur and the efficiency decrease is also small. For example, with FAT, the cluster size that can be selected when formatting is in kilobytes, so when a 70MB file is recorded, it is dispersed across approximately 7,000 cluster locations, and the disadvantage is that the cluster writing locations gradually become fragmented as writing and erasing are repeated. However, with this method, consecutive clusters of 10MB each are secured and then the container file is written to those consecutive clusters, thereby suppressing fragmentation. (2) "Recording video data of a specific unit time into one fixed-length file (visible at initialization)"

[0072] When the controller MC detects that the "Initialize" button has been touched while "Record video data of a specific unit time in one fixed-length file (visible at initialization)" is selected, it performs a normal FAT32 format in which the entire SD card is treated as one partition and that partition is formatted in FAT32 format, then creates 400 70MB fixed-length AVI files (with file names from 0001.avi to 0400.avi) on the 32GB SD card and moves to recording processing. This AVI file records a completely black screen as the internal video information. In the recording process, a cluster is reserved at a fixed location for files that can be read by the FAT32 file system used in Windows 10, and the recording of the AVI file containing video information is performed by overwriting each AVI file that uses the previously reserved clusters to the extent that the size of the AVI file is not exceeded. That is, the imaging information acquired from the CCD camera 13 for each frame is compressed with a predetermined codec (e.g., H.254, etc.) to generate frame information by adding GPS information and acceleration information as subtitle data in text format, and 60 seconds of frame information is overwritten as one container file (e.g., AVI container) onto the file created in the initialization process. In this way, a file containing video data is recorded without changing the location of the cluster of the file. The video information is a variable bit rate, and the fixed length size (70 MB) is set to be larger than the size of the container file containing the generation information including the video information when recording for one minute at the maximum bit rate of the variable bit rate (8 Mbps in this embodiment) (8 Mbps*60 seconds / 8 bytes=60 MB in this embodiment). One minute of generation information is overwritten and recorded into the first AVI file, and the next minute of generation information is overwritten and recorded into the second AVI file, and so on. When the overwriting of the 400th AVI file is completed, the process returns to overwriting and recording the first AVI file. By repeating this process, recording can be performed continuously in clusters that have been secured in advance as files.

[0073] In this way, the video data per unit time is overwritten in a pre-created fixed-length file, which almost certainly prevents file fragmentation and reduces the possibility of damage to management areas such as the FAT.

[0074] In this embodiment, the unit time is set to one minute. In this way, even if an unexpected power outage or unexpected removal of the medium occurs while the drive recorder 1 is recording video information, the amount of data that may be lost is limited to one minute or less.

[0075] In addition, in this embodiment, only the contents are overwritten and updated without writing to the file management area. Therefore, for example, the possibility of problems occurring in conventional systems, such as the management area of ​​a video file recorded on a recording medium becoming unreadable by a personal computer due to an unexpected power outage of the system or an unexpected removal of the recording medium while updating the file management area, can be significantly reduced. Therefore, it is no longer necessary to perform periodic formatting of the recording medium, which was previously required, and a drive recorder that is superior to conventional ones can be provided.

[0076] In this embodiment, the AVI file using the pre-allocated clusters has a function of generating a file capable of playing video in Windows 10, which is the operating system of the personal computer 35, during the initialization process of the SD card. Therefore, the AVI file that appears when the SD card is read by the personal computer immediately after the initialization process of the SD card is completed can be played back to view the video. The video data of the playable AVI file is an image that continues to display a black screen when played back, but it may be an image completely covered with another color (e.g., an image of a blue screen), or an image that continues to display a character string such as "This is an unrecorded file". In addition, an AVI file with the above structure that includes a predetermined video may be stored in the database 32 of the drive recorder 1 in advance, and this file may be copied from the database 32 to the SD card when a file is generated during the initialization process. (3) "Recording video data of a specific unit time in one fixed-length file (invisible at initialization)"

[0077] In the process (2) above, the process of "Create 400 fixed-length AVI files of 70 MB on a 32 GB SD card and proceed to recording process" is changed to "Create 400 fixed-length AVI files of 70 MB on a 32 GB SD card, replace the first byte of the file name of the directory entry of all files with byte data indicating deletion (0xE5 in this embodiment), and when starting to write data to the AVI files, return the first byte of the file name of the file to the original byte data."

[0078] An AVI file that uses clusters secured in advance in this way is generated as an invisible file that is deleted in Windows 10, the operating system of computer 35, during the SD card initialization process, and has the function of making the file being written into a visible file when writing generated information including video information to the AVI file.

[0079] This prevents files that use pre-allocated clusters and contain no video data from being seen when the recording medium is read by the computer 35 immediately after the SD card has been initialized. (4) "Recording variable bit rate video data as much as possible into one fixed length file (visible at initialization)"

[0080] In the above (3), the generation information including one minute of video information is overwritten and recorded in a fixed-length file generated in advance by the initialization process, one minute of generation information is overwritten and recorded in the first AVI file, the next minute of generation information is overwritten and recorded in the second AVI file, and so on. When the overwriting of the 400th AVI file is completed, the process returns to overwriting the first AVI file, but this is not recorded as one minute of video information, but is recorded so that the content of the AVI file is filled as much as possible. In other words, the capacity of one fixed-length AVI file in which the generation information has been recorded is monitored and recorded so that the variable bit rate video information is recorded as fully as possible in one fixed-length AVI file, and the fixed-length AVI file to be recorded is changed to the next AVI file before the capacity is exceeded.

[0081] In this way, the video time recorded in the fixed-length AVI file of 1 will not be constant, but it will solve the problem that occurs in the above method (3) where the video is not recorded in the entire fixed-length AVI file, reducing the amount of video time that can be recorded on the SD card. In a method where an AVI file is created in advance (clusters are reserved in fixed locations) and the cluster locations are overwritten without changing, the fact that the file size is determined in advance means that the processing will be performed so that an AVI file that exceeds that file size will never be created. Therefore, the biggest drawback of method (3) is that it leaves an enormous amount of free space on the SD card, especially when shooting video with a low bit rate and little change. However, this problem can be solved by using method (4).

[0082] The configuration for recording as much as possible into the fixed-length AVI file 1 is such that at least the video between the key frames (the frame from the key frame to the frame before the next key frame) is buffered in the RAM in the controller MC of the drive recorder 1 so that the next fixed-length file starts from a key frame, and if the video between the key frames can still fit into the AVI file currently being written, it is written into the AVI file currently being written, and if it cannot fit (overflows), it is controlled so that it is recorded into the next fixed-length AVI file. The key frames are between I frames, and the content of the next fixed-length file does not start from a P frame or B frame, so it is configured to always start from an I frame. (5) In the case of "Variable bit rate video data is recorded as much as possible into one fixed-length file (invisible at initialization)" Similar to the change in processing (3) for (2) above, a change in processing for (4) is made. (6) "Video data is recorded continuously in one very large file (visible at initialization)"

[0083] When the controller MC detects that the "Initialize" button has been touched while "Record video data to be recorded at all times in one very large file (visible at initialization)" is selected, it performs a normal FAT32 format in which the entire SD card is treated as one partition and that partition is formatted in FAT32 format, then creates seven 4GB fixed-length AVI files (file names 0001.avi to 0007.avi) on the 32GB SD card and moves to recording processing. This AVI file records a completely black screen as the internal video information. In the recording process, clusters are reserved at a fixed location for files that can be read by the FAT32 file system used in Windows 10, and the recording of AVI files containing video information is performed by overwriting each AVI file that uses the previously reserved clusters to the extent that the size of the AVI file is not exceeded. The imaging information acquired from the CCD camera 13 for each frame is compressed with a predetermined codec (e.g., H.254, etc.) to generate frame information by adding GPS information and acceleration information in text format as subtitle data to the video information, and the frame information is overwritten as one container file (e.g., AVI container) until the file created in the initialization process is filled. At this time, the content of the AVI file is filled as much as possible. That is, the capacity of one fixed-length AVI file in which the generated information is recorded is monitored and recorded so that the video information of the variable bit rate is filled as much as possible in one fixed-length AVI file, and the fixed-length AVI file to be recorded is changed to the next AVI file before the capacity is exceeded. In this way, a file containing video data is recorded without changing the location of the cluster of the file. In this way, the drive recorder 1 has the function of constantly recording generated information, including video information, to the SD card while the power is on, and during the SD card initialization process, multiple files that use pre-allocated clusters are created in advance as a single very large 4GB file, and the video information to be recorded at all times is recorded in this single very large 4GB file.In this way, the process can be simplified and the possibility of fragmentation can be reduced more than before.

[0084] In this embodiment, the very large file is, for example, 32 GB or less, which is the capacity of the SD card, and 4 GB, which is the maximum capacity of the file of the file system that stores the file. However, by changing the formatting to exFAT, this very large file may be, for example, a file having a capacity of more than half the capacity of the SD card. In particular, the size of this single file should be more than half the capacity of the SD card (and, for example, less than the capacity of the SD card). Also, within this range, a slider may be further displayed on the screen of FIG. 6 displayed on the display unit 25, and a function may be provided for allowing the user to set the capacity by operating (dragging) the slider. (7) "Video data is recorded continuously in one very large file (invisible at initialization)" Similar to the change in processing (3) for (2) above, a change in processing for (6) is performed.

[0085] In the formatting and recording methods (1) to (7) described above, the format format is FAT32, so that files can be viewed using applications such as Explorer in Windows 10 on the personal computer 35. Also, in the formatting and recording methods (1) to (7) described above, files containing video information are generated in a file format that can be played on Windows 10 on the personal computer 35, so that AVI files recorded on the SD card can be played on Windows 10 on the personal computer 35. (8) In the case of "recording in a proprietary format"

[0086] When the controller MC detects that the "Initialize" button has been touched while "Record in original format" is selected, it creates two partitions with half the size of the entire SD card. One is the top partition, which is formatted in FAT32 format. The other rear partition is not formatted, and frame information is generated by compressing the image information acquired from the CCD camera 13 for each frame using a specified codec (e.g., H.254, etc.) and adding GPS information and acceleration information in text format as subtitle data to the video information, and the frame information is recorded directly and sequentially. In other words, the rear partition does not have a management area like FAT, and as a result, the index of the video information is not written to the management area, and the generated information including the video information is packed and written sequentially to the SD card.

[0087] By doing this, the concept of fragmentation is eliminated. Also, the video information cannot be viewed using only the standard functions of Windows 10 on the PC 35. Therefore, the security element of the system is also high. Therefore, it is no longer necessary to perform periodic formatting of the recording medium, which was previously necessary, and a system that is superior to the conventional system can be provided.

[0088] Also, for example, in functions (1) to (7), if the recording medium is removed from the system while the management area such as the FAT is being written, depending on the timing, the entire contents of the recording medium may be lost. This does not happen with method (8). It is advisable to configure functions (1) to (7) so that the management area such as the FAT is not written to as much as possible when recording video information, but there are cases where it is difficult to configure all of them in this way. In such cases, method (8) should be selected.

[0089] In the configuration of (8), a function may be provided for performing at least one of the recording processes (1) to (7) in parallel with the recording process of (8) for a partition that has the same format as that used by Windows 10 of the personal computer 35 for the SD card. In this way, even if any of the partitions is destroyed, the video data can be read and played back from the undestroyed partition.

[0090] In the method (8), since the video information is variable length, it is very difficult to find the beginning of a video frame. Therefore, it is a good idea to attach chain data to each frame so that it can be searched between frames. It is a good idea to have a system where each frame has a directory entry, as in FAT. The disadvantage is that it is not visible in a file search application such as Explorer in a general operating system of a personal computer, so a dedicated application is required. For example, when the recording medium is an SD card, writing to a continuous area is faster when accessing the SD card, but writing to discontinuous areas reduces the writing speed dramatically. However, if configured as in (10), this can be prevented, and for example, simultaneous writing of a total of four streams can be achieved for two cameras / continuous recording and events separately. Also, in a communication type system, writing eight streams by adding dirty video (video with low capacity) is relatively easy compared to other recording methods.

[0091] In the recording processes (1) to (7), the video information may also be recorded with first information for going back a predetermined time without using a management area and second information for going back a predetermined number of frames without using a management area, and the drive recorder 1 may be provided with a play button, a rewind button, and a fast-forward button for an SD card, so that playback is started when the controller MC detects that the play button is pressed, and the video may be cue-matched based on the first and second information when the controller MC detects that the rewind or fast-forward button is pressed. Also, the video may be cue-matched based on the first and second information on a viewer software executed on the personal computer 35 in FIG. 5.

[0092] According to the functions (1) to (8) described above, a drive recorder 1 that records generated information on an SD card accessible to the drive recorder 1 can be realized. When the SD card is accessible from the PC 35, at least a portion of the SD card can be read by Windows 10 on the PC 35. However, the drive recorder can record the generated information using a method different from the writing method used by Windows 10.

[0093] In this way, the information recorded by the drive recorder 1 can be read by Windows 10, and recording can be performed in a method that is convenient for the drive recorder 1 and different from the writing method in Windows 10. In this way, both can be achieved at the same time.

[0094] In this embodiment, the recording medium accessible by the drive recorder 1 is an SD card, but it may also be a recording medium connected to the drive recorder 1, such as an SSD or HDD connected via a USB cable.

[0095] In this embodiment, the SD card is accessible from PC 35 when the SD card is inserted into an SD card reader / writer connected to PC 35; however, for example, the drive recorder 1 may have a wireless communication function (such as a WiFi network connection function) and PC 35 may also have a wireless communication function that can connect to the drive recorder 1, and the SD card in the drive recorder 1 may be accessible from PC 35. The portion that is FAT32 in this embodiment may be at least one of FAT16, FAT32, exFAT, etc., depending on the capacity of the SD card.

[0096] In addition, it is preferable that the Windows 10 of the personal computer 35 is provided with the viewer software shown in FIG. 5 that has the function of acquiring, expanding, and displaying video information from the generated information in the rear partition recorded in the process of (10) above.

[0097] Alternatively, the viewer software may be configured as software that provides the generation information in the rear partition recorded in the process of (10) above as a file that can be referenced, as a Windows 10 device driver (a driver that processes the file system), rather than as software that performs a special read process to read the rear partition of (10).

[0098] In this embodiment, the PC 35 is used as an example, but the PC may be replaced with a "smartphone" or a "tablet." In these cases, the Android operating system may be used as a general operating system.

[0099] The scope of the present invention is not limited to the configurations explicitly described in the specification, but includes combinations of various aspects of the present invention disclosed in this specification. The configurations of the present invention that are to be patented are specified in the attached claims, but it is our intention to include configurations disclosed in this specification in the claims in the future, even if they are not currently specified in the claims.

[0100] The present invention is not limited to the configuration described in the above-mentioned embodiment. The components of each of the above-mentioned embodiments and modifications may be arbitrarily selected and combined. Any components of each of the embodiments and modifications may be arbitrarily combined with any components described in the means for solving the invention or any components that embody any components described in the means for solving the invention. We intend to acquire rights to these as well through amendments to this application or divisional applications. Even if there is a description such as "in the case of" or "when", this is not intended to describe a configuration that is limited to that case or time. We also disclose configurations that are not in these cases or times, and we intend to acquire rights. Furthermore, the parts described in order are not limited to this order. We also disclose configurations in which some parts are deleted or the order is changed, and we intend to acquire rights.

[0101] In addition, we intend to obtain rights to the overall design or partial design by converting to a design registration application. The drawings depict the entire device in solid lines, but they include not only the overall design but also partial designs claimed for a part of the device. For example, some parts of the device may be partial designs, and the drawings include some parts of the device as partial designs regardless of the parts. A part of the device may be a part of the device, or a part of that part. We intend to obtain rights to the overall design, as well as partial designs in which any part of the solid line part of the drawing is shown as a broken line part. In addition, the modules, parts, and components inside the device's casing, all of which are shown in the drawings, are subject to trade independently, and we intend to obtain rights to them by converting to a design registration application. [Explanation of symbols]

[0102] 1...Drive recorder, 2...Main body case, 15...Acceleration sensor, 24...GPS receiver, 31...SD card reader / writer, 32...Database, 35...PC, 36...SD card reader / writer, 45...Monitor, MC...Controller.

Claims

1. A system having a function of recording generated information on a recording medium, a function of recording the generated information in a manner that is readable by a general operating system of a personal computer when the recording medium is accessible from the personal computer, but that is different from a writing method used by the general operating system; When the recording medium is inserted in a personal computer, at least a part of the recording medium can be read by a general operating system of the personal computer, but the method differs from the writing method in the general operating system in that, in the initialization process of the recording medium of the system, clusters are reserved at a fixed location for files that can be read by a file system adopted in the general operating system of the personal computer, and the generated information is recorded by overwriting a file that uses the clusters reserved in the initialization process to the extent that does not exceed the size of the file, thereby recording a file containing video data without changing the location of the cluster of the file, In the initialization process of the recording medium, a plurality of files using the clusters secured in the initialization process are created in advance as fixed-length files, The video data is a variable bit rate, and the recording function is provided for setting the size of the fixed length so that the video data of a predetermined unit time is recorded in one file of the fixed length to be larger than the size of data including the video data when recorded for the predetermined unit time at the maximum bit rate of the variable bit rate. A system characterized by.

2. A system having a function of recording generated information on a recording medium, a function of recording the generated information in a manner that is readable by a general operating system of a personal computer when the recording medium is accessible from the personal computer, but that is different from a writing method used by the general operating system; When the recording medium is inserted in a personal computer, at least a part of the recording medium can be read by a general operating system of the personal computer, but the method differs from the writing method in the general operating system in that, in the initialization process of the recording medium of the system, clusters are reserved at a fixed location for files that can be read by a file system adopted in the general operating system of the personal computer, and the generated information is recorded by overwriting a file that uses the clusters reserved in the initialization process to the extent that does not exceed the size of the file, thereby recording a file containing video data without changing the location of the cluster of the file, In the initialization process of the recording medium, a plurality of files using the clusters secured in the initialization process are created in advance as fixed-length files; The video data is of variable bit rate, and the device has a function of monitoring the amount of data recorded in one fixed-length file and changing the fixed-length file to be recorded so that the video data of the variable bit rate is recorded in one fixed-length file. A system characterized by.

3. A system having a function of recording generated information on a recording medium, a function of recording the generated information in a manner that is readable by a general operating system of a personal computer when the recording medium is accessible from the personal computer, but that is different from a writing method used by the general operating system; When the recording medium is inserted in a personal computer, at least a part of the recording medium can be read by a general operating system of the personal computer, but the method differs from the writing method in the general operating system in that, in the initialization process of the recording medium of the system, clusters are reserved at a fixed location for files that can be read by a file system adopted in the general operating system of the personal computer, and the generated information is recorded by overwriting a file that uses the clusters reserved in the initialization process to the extent that does not exceed the size of the file, thereby recording a file containing video data without changing the location of the cluster of the file, the system has a function of constantly recording the video data on the recording medium while the power is on; In the initialization process of the recording medium, a file using the clusters secured in the initialization process is created in advance as a very large single file, The constantly recorded video data is provided with a function for recording in the very large file. A system characterized by.

4. A system having a function of recording generated information on a recording medium, a function of recording the generated information in a manner that is readable by a general operating system of a personal computer when the recording medium is accessible from the personal computer, but that is different from a writing method used by the general operating system; When the recording medium is inserted in a personal computer, at least a part of the recording medium can be read by a general operating system of the personal computer, but the method differs from the writing method in the general operating system in that, in the initialization process of the recording medium of the system, clusters are reserved at a fixed location for files that can be read by a file system adopted in the general operating system of the personal computer, and the generated information is recorded by overwriting a file that uses the clusters reserved in the initialization process to the extent that does not exceed the size of the file, thereby recording a file containing video data without changing the location of the cluster of the file, The file using the reserved cluster is generated as an invisible file that is a file deleted in the operating system of the personal computer during initialization processing of the recording medium, and when writing the video data, the file to be written is made a visible file that is an undeleted file. A system characterized by.

5. A system having a function of recording generated information on a recording medium, a function of recording video data based on imaging data captured by an imaging means as the generated information in a manner readable by a general operating system of the personal computer when the recording medium is accessible from the personal computer but different from a writing method in the general operating system; The writing method in the above general operating system is such that when data is written to a file and the file size changes from 0 to 1 or more, one unused cluster is allocated at that time, and that cluster number is set in the directory entry of the file. Thereafter, whenever the file size increases and the cluster being written overflows, a new cluster is allocated and a cluster chain is formed. The method different from the writing method in the general operating system includes a configuration in which, when generating a file including video data, a cluster chain is formed by pre-allocating a predetermined number of unused clusters with consecutive numbers, and data including the video data is continuously written in an area having a size obtained by multiplying the cluster size by the predetermined number to generate the file, The recording medium has a function of adding, to the video data, first information for going back a predetermined time in the past without using a management area having a directory entry present on the recording medium, and second information for going back a predetermined frame in the past without using a management area having a directory entry present on the recording medium, and cueing the video based on the first information and the second information. A system characterized by.

6. A program for causing a computer to realize all the functions of the system according to any one of claims 1 to 5.

Images