JP2015114887A - Monitor-purposed recorder and data recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a size of a buffer memory that temporarily stores data to be recorded in a hard disc drive.SOLUTION: A monitor-purposed recorder 100 comprises: an encoder 103 that encodes a video image of a camera 10 to generate video image data; a buffer memory 105 that temporarily stores the video image data; and a control unit 104 that executes a control of recording the video image data in a hard disc 114 of a hard disc drive 110 via an HDD controller 106. The control unit 104 is configured to record the video image in the hard disc 114 using a flash command for certifying recording data, and in this case, when the flash command continues and a flash control period elongates, for preventing the buffer memory 105 from overflowing, the control unit 10 shortens the flash control period using the flash command, separately.

Description

  The present invention relates to a technique for reducing the size of a buffer memory that temporarily stores data to be recorded in a hard disk drive.

  In recent years, surveillance systems composed of surveillance cameras and surveillance recorders have been used for buildings such as apartments and buildings, banks and convenience stores, and street corners for the purpose of crime prevention and early resolution of incidents. Has been installed.

  The surveillance recorder has a function to record and save the video of multiple surveillance cameras for a certain period, and when that period expires, the old recorded video data is overwritten with new video data to maintain continuity of recording. doing. The monitoring recorder generally includes a hard disk drive (HDD), records video data on the hard disk (HD), and includes a cache memory in order to improve the writing performance. In addition, hard disks have high random access performance and large capacity, and are configured with disk drives such as RAID (Redundant Arrays of Inexpensive Disks) systems that combine multiple hard disks to provide redundancy and reliability. Has come to improve.

  The surveillance recorder continuously records the video from the surveillance camera in an unattended time zone or place where there is no surveillance person, so that video recording can be performed correctly even after a power failure. Need to continue. When the monitoring recorder has a cache memory, the order of video data input to the hard disk drive may differ from the order of video data written to the hard disk in the hard disk drive. This is a phenomenon for improving the write performance. For this reason, there is a problem that it is impossible to guarantee to what extent the data read after recovery from a power failure is correct.

  Japanese Patent Application Laid-Open No. H10-228688 discloses that a flash control for forcibly writing the contents of a cache memory to a hard disk is executed at a predetermined timing as a guarantee method for data recorded on the hard disk.

JP 2001-184246 A

  While the flash control is being performed, the hard disk drive does not accept data input. For this reason, the monitoring recorder is provided with a buffer memory, whereby video data output from the camera is temporarily stored in the buffer memory.

  Here, when the monitoring recorder includes a hard disk drive having a cache memory and a buffer memory, a recording area is provided in the hard disk for each of the plurality of monitoring cameras, and a predetermined area is set for each recording area. Assume that the flash control is executed periodically.

  In this case, the flash control timing applied to different recording areas overlaps and the flash control is continuously executed. Therefore, the amount of data stored in the buffer memory has a large peak during the flash control.

  In order to prevent data from overflowing from the buffer memory, it is necessary to set the size of the buffer memory in accordance with the peak. When the amount of data stored in the buffer memory has a large peak, it is necessary to provide a large-capacity buffer memory corresponding to the peak, which is not economical. In addition, when the size of the buffer memory is increased, there is a problem that the cost increases. However, Patent Document 1 does not describe a technique for reducing the size of the buffer memory.

  Therefore, an object of the present invention is to provide a technique for reducing the size of a buffer memory that temporarily stores data to be recorded in a hard disk drive.

  In order to solve the above problems, a monitoring recorder according to the present invention includes an encoder that encodes a video signal of a camera to generate video data, a buffer memory that temporarily stores the video data, and a read from the buffer memory. A control unit that executes a control for recording the recorded video data at a designated address of the hard disk of the hard disk drive, wherein the control unit guarantees the recorded data using a flash command. To record the video data on the hard disk, and execute a second flash control different from the first flash control before a predetermined time before the first flash control is executed.

  According to the present invention, the size of a buffer memory that temporarily stores data to be recorded in a hard disk drive can be reduced.

It is a figure which shows the function example of the recorder for monitoring. It is a figure which shows an example of the write state by a write command. It is a figure which shows an example of the write state by a flash command. It is a figure which shows an example in case the written data are guaranteed. It is a figure which shows an example in case the written data are not guaranteed. FIGS. 4A and 4B are diagrams illustrating an example of timing for executing flash control, where FIG. 4A illustrates a case where flash control is executed at the end of a management block, and FIG. 4B illustrates a case where the timing interval of flash control is FIG. (C) represents a case where the flash control is forcibly executed according to time. It is a figure which shows an example when a buffer memory overflows, (a) represents the state written in a cache memory, (b) represents the timing of writing to a hard disk, (c) represents the occupation amount of a buffer memory Represents. It is a figure which shows an example in the case of avoiding the overflow of a buffer memory, (a) represents the state written in a cache memory, (b) represents the timing of writing to a hard disk, (c) represents the occupation of buffer memory Represents an amount. It is a figure which shows the example of a processing flow in a 1st Example. It is a figure which shows the example of a processing flow in a 2nd Example. It is a figure which shows the example of a processing flow in a 3rd Example.

  Here, a mode for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail with reference to the drawings as appropriate.

  First, an example of functions of the monitoring recorder 100 will be described with reference to FIG. FIG. 1 shows only the functions necessary for explaining the present invention, and does not show all the functions of the monitoring recorder 100.

  As shown in FIG. 1, the monitoring recorder 100 has a function of connecting one or more cameras 10 and recording video data. The monitoring recorder 100 includes at least an A / D (analog / digital converter) 101, a MIX (mixer) 102, an encoder 103, a control unit 104, a buffer memory 105, an HDD controller 106, and a hard disk drive (HDD) 110.

The A / D 101 has a function of converting an analog video signal output from the camera 10 into a digital signal.
The MIX 102 has a function of mixing digital signals and converting them into signals of a predetermined format.

The encoder 103 has a function of compressing a signal output from the MIX 102 and converting it into video data (hereinafter also referred to simply as data).
The control unit 104 has a function of reading / writing video data from / to the buffer memory 105 and a function of controlling the HDD controller 106 in order to record the video data output from the encoder 103 in the hard disk drive 110. The control unit 104 has a function of acquiring the current time from a timer (not shown) or the like. The control unit 104 is configured by a CPU (Central Processing Unit) and a main memory (not shown), and an application program stored in a storage unit (not shown) is developed in the main memory to realize the function. When recording video data on the hard disk drive 110, the control unit 104 uses an HDD command (for example, an ATA (Advanced Technology Attachment) command) and designates a write destination address of the hard disk 114 via the HDD controller 106. Write.

The buffer memory 105 is a storage device. Based on the control of the control unit 104, the video data is temporarily stored and read out at a predetermined timing.
The HDD controller 106 is controlled by the control unit 104 and has a function of outputting an HDD command, a write destination address, and video data to the hard disk drive 110. Commands for writing video data to the hard disk drive 110 include a write command and a flash command. The difference between these commands will be described later.

The hard disk drive 110 includes at least an I / F (interface) 111, a controller 112, a cache memory 113, and a hard disk 114.
The I / F 111 is an interface such as a SATA (Serial ATA) I / F, for example, and has a function of accepting an HDD command of the HDD controller 106, a write destination address, and video data.

  The controller 112 receives the HDD command, write destination address, and video data via the I / F 111, stores the video data in the cache memory 113, interprets the HDD command, reads the video data from the cache memory 113, and reads the hard disk 114 has a function of executing control to write data to 114. Specifically, when receiving a write command, the controller 112 controls the order of video data to be written to the hard disk 114 in order to improve the writing performance. Further, when the controller 112 receives a flash command, the controller 112 executes control to write all video data in the cache memory 113 to the hard disk 114.

The cache memory 113 is a storage device, and based on the control of the controller 112, data is temporarily stored and read at a predetermined timing. The read data is erased from the cache memory 113.
The hard disk 114 is a storage device, and data is recorded or read based on the control of the controller 112.

  Next, a write command to the hard disk 114 will be described with reference to FIGS. 2A and 2B (see FIG. 1 as appropriate). FIG. 2A shows an example of a write state by a write command, and FIG. 2B shows an example of a write state by a flash command.

  In FIG. 2A, it is assumed that the input data to the I / F 111 of the hard disk drive 110 is input in the order of “A”, “B”, and “C” using the write command, as shown in the balloon of S1a. In this case, the write data recorded on the hard disk 114 may be changed in the order of “B”, “A”, and “C” as shown in the balloon of S2a in order to improve the write performance. As shown in the data “A”, when the write command is used, the data is not always written to the hard disk 114 immediately, and may be accumulated in the cache memory 113 for a while.

  In FIG. 2B, as shown in the balloon of S1b, in order to perform the flash control, the flash command “f” is added to the input data after “A”, “B”, and “C”. When the controller 112 receives the flash command, the controller 112 forcibly writes all data in the cache memory 113 to the hard disk 114. Therefore, the write data recorded on the hard disk 114 is recorded on the hard disk 114 in the input order of “A”, “B”, and “C” as shown in the balloon of S2b based on the flash command. However, the hard disk drive 110 does not accept data from the HDD controller 106 during the flash control. Therefore, the amount of video data stored in the buffer memory 105 (buffer memory occupation amount) increases during the flash control.

  Next, flash control for guaranteeing data written to the hard disk 114 using a flash command will be described with reference to FIGS. 3A and 3B (see FIG. 1 as appropriate). FIG. 3A shows an example when the written data is guaranteed, and FIG. 3B shows an example when the written data is not guaranteed.

  In FIG. 3A, it is assumed that the input data input to the I / F 111 of the hard disk drive 110 is in the order of “A”, “f”, “M”, “f”, and “B”, as shown in the balloon of S3a. Here, “M” is a marker (which may include an error correction code or an error detection code), and is written after “A” in order to guarantee recording of “A”. If “M” is written correctly, it can be assured that “A” is normal. Then, the data written to the hard disk 114 is written in the order of “A”, “M”, and “B” as shown in the balloon of S4a when there is no failure such as a power failure at the time of writing. That is, it can be seen that the data “A” can be guaranteed.

  On the other hand, in FIG. 3B, as shown in the balloon of S3b, when the I / F 111 of the hard disk drive 110 receives the input data “A”, “f”, “M”, “f”, “B”, the input data “M” represents a case where a power failure occurs. Therefore, the write data recorded on the hard disk 114 is only “A (Italic)” as shown in the balloon of S4b. That is, it can be seen that “M” is not correctly recorded at the time of reading after recovery from a power failure, and therefore data of “A (italic)” cannot be guaranteed. The data block can be effectively utilized by overwriting new data on the data block in which “A (italic)” is written.

  Next, an example of timing for executing the flash control will be described with reference to FIGS. 4A, 4B, and 4C (see FIG. 1 as appropriate). 4A shows a case where the flash control is executed at the end of the management block, and FIG. 4B shows a case where the timing interval of the flash control is longer than that in FIG. 4A. (C) represents a case where the flash control is forcibly executed according to time.

There are two cases (first case and second case) of timing for executing the flash control.
In the first case, for example, when the management block indicating the unit for reliably guaranteeing the recording of the video data is 10 MB, and the recorded video data exceeds 10 MB (beyond the end of the management block, the start of the next management block) This is a case where the control unit 104 executes flash control using a flash command as shown in FIG. 3A. One or more management blocks are set in a recording area (not shown) of the hard disk 114 allocated to each camera 10 as an area for recording video data. Note that the management block is not limited to 10 MB, and may have another capacity. If a power failure occurs while video data is being recorded in the management block, it is possible to invalidate the management block at the time of the power failure after returning from the power failure by confirming that there is no marker. It should be noted that by newly overwriting video data in the invalid management block location, that location can be used effectively.

  The second case is a case where the flash control is forcibly executed according to time in a predetermined cycle (including the case of a constant interval). For example, when the camera 10 outputs only a few frames or less of video per second, the same processing as in the first case is performed, so that it is very difficult to fill one management block with video data. Will take a long time. If a power failure occurs, the long-term video data will be lost. Therefore, the control unit 104 executes flash control every 30 seconds, for example. Note that the predetermined period is not limited to 30 seconds, and may be another time length.

  FIG. 4A shows the case of the first case, where the horizontal axis represents time, and the vertical axis represents the write position of the management block. A broken line 401a represents the end of the management block.

  When the write capacity per unit time is constant, as shown in FIG. 4A, the write position is indicated by a write position line 402 (solid line) as a substantially straight line with respect to time. The assumption that the write capacity per unit time is constant has no problem for the reason described later. The reason is that, generally, when the image of the camera 10 changes suddenly, the amount of information corresponding to the change increases, but even if the amount of information is reduced and kept constant, there is no visual discomfort. When the writing position reaches the end of the management block (broken line 401a), the control unit 104 performs flash control. In FIG. 4A, the video data is transferred to the next start end of the management block (the intersection with the horizontal axis on the vertical axis). ) In FIG. 4A, the flash control is executed at times t2, t3, t4, and t5. The range indicated by reference numeral 404a represents a flash control time prediction period (predetermined range). When the writing position reaches this range, the control unit 104 predicts the time when the flash control is executed, It is set to determine whether or not they are continuous (the timings overlap). Details of the determination process of the flash control will be described later. When there are a plurality of management blocks in the recording area, the control unit 104 may record video data in the next management block after executing the flash control.

  FIG. 4B shows another first case, in which the flash control timing interval is longer than that in FIG. 4A. In FIG. 4B, the horizontal axis represents time, and the vertical axis represents the write position of the management block. A broken line 401b represents the end of the management block. Note that the size of the management block in FIG. 4B (position of the broken line 401b) and the size of the management block in FIG. 4A (position of the broken line 401a) may be the same or different. I do not care.

  When the write capacity per unit time is constant, as shown in FIG. 4B, the write position is indicated by a write position line 403 (dashed line) as a substantially straight line with respect to time. When the writing position reaches the end of the management block (broken line 401b), the control unit 104 performs flash control. In FIG. 4B, the video data is transferred to the next start end of the management block (the intersection with the horizontal axis on the vertical axis). ) In FIG. 4B, the flash control is executed at times t3 and t5. The range indicated by reference numeral 404b represents a flash control time prediction period (predetermined range). When the write position reaches this range, the control unit 104 predicts the time when the flash control is executed, and other flash controls. It is set to determine whether or not they are continuous (the timings overlap). Details of the determination process of the flash control will be described later. When there are a plurality of management blocks in the recording area, the control unit 104 may record video data in the next management block after executing the flash control.

  FIG. 4C shows a second case, in which the flash control is forcibly performed according to time. In FIG. 4C, the control unit 104 performs the flash control at a predetermined cycle (including the case of a constant cycle). In FIG. 4C, the flash control is executed at times t2, t3, t4, and t5. The range indicated by reference numeral 405 represents a flash control time prediction period (predetermined range), and when the current time reaches this range, the control unit 104 predicts the time when the flash control is to be executed, and the other flash It is set to determine whether or not it is continuous with the control (timing overlaps). Details of the determination process of the flash control will be described later.

  The monitoring recorder 100 is provided with a recording area (not shown) for each camera 10, and the flash control shown in FIG. 4 (a), the flash control shown in FIG. 4 (b), and the flash shown in FIG. 4 (c). Control can be performed for each camera 10 simultaneously. In such a case, at the times t2, t3, t4, and t5, the flash control timings shown in FIGS. 4A and 4C overlap, and the flash control is executed continuously. At times t3 and t5, the flash control timings shown in FIGS. 4A, 4B, and 4C overlap and the flash control is executed continuously. While the flash control is being executed, the output data of the encoder 103 is accumulated in the buffer memory 105, so that the buffer memory occupation amount increases. That is, as the continuous time of the flash control becomes longer, the size of the buffer memory 105 must be increased in order to prevent the buffer memory 105 from overflowing.

  For example, FIGS. 5A, 5B, and 5C show an example in which the buffer memory 105 overflows (see FIG. 1 as appropriate). 5A shows a state in which data is written to the cache memory 113, FIG. 5B shows a timing of writing to the hard disk 114, and FIG. 5C shows an occupation amount of the buffer memory 105.

  FIG. 5A shows the video data of the four cameras 10 as “a”, “b”, “c”, and “d” for each camera 10 with respect to the video data written to the cache memory 113. The horizontal axis represents time. Normally, video data is written into the cache memory 113 using a write command (not shown). In flash control for guaranteeing recording data, markers “Ma” 51, “Mb” 52, “Mc” 53, and “Md” 54 are written in the cache memory 113 in addition to video data. In FIG. 5A, “f” represents a flash command. Note that the timing of the flash control for guaranteeing the recording data is not changed as shown in FIGS. 4 (a), 4 (b), and 4 (c).

  FIG. 5B shows the timing of writing to the hard disk 114. In particular, a range indicated by reference numeral 503 represents a write command control period, and a range indicated by reference numeral 504 represents a flash command control period. Note that processing by one flash command takes more time than processing by one write command because all data in the cache memory 113 is written to the hard disk 114.

  In FIG. 5C, the vertical axis represents the buffer memory occupation amount, and the horizontal axis represents time. A broken line 501 represents the maximum possible occupation amount (buffer memory threshold) of the buffer memory 105. That is, when the broken line 501 is exceeded, it is determined that the overflow has occurred. A solid line 502 indicates a buffer memory occupation amount curve.

  The tendency of the buffer memory occupation curve 502 will be described. Since the hard disk drive 110 does not accept data during the flash command control period 504 shown in FIG. 5B, the value of the buffer memory occupation curve 502 increases. The state exceeds the broken line 501. This is because a plurality of flash control timings for guaranteeing the recording data are overlapped and the flash control is continued. This is also because the amount of data stored in the cache memory 113 is large before performing the flash control for guaranteeing the recording data. The continuous flash control means that the write command process is not executed between the flash command process and the next flash command process.

  Therefore, in this embodiment, in order to reduce the amount of data stored in the cache memory 113 when executing the flash control for guaranteeing the recording data, the flash control (the first control for guaranteeing the recording data) is performed. In addition to (1 flash control), flash control (second flash control) for preventing overflow is executed. Here, an example of avoiding overflow of the buffer memory 105 will be described with reference to FIGS. 6A shows a state in which data is written to the cache memory 113, FIG. 6B shows timing of writing to the hard disk 114, and FIG. 6C shows an occupation amount of the buffer memory 105. 6A, 6B, and 6C, the same reference numerals as those in FIGS. 5A, 5B, and 5C denote the same components.

  In FIG. 6A, as in FIG. 5A, the video data of the four cameras 10 is “a”, “b”, “c”, “d” for each camera 10 for the video data written to the cache memory 113. It is represented by The horizontal axis represents time. FIG. 6A differs from FIG. 5A in that a flash command “f” 65 is used after the top video data “a”.

  FIG. 6B shows the timing of writing to the hard disk 114. A range indicated by reference numerals 603 and 605 represents a flash command control period, and a range indicated by reference numeral 604 represents a write command control period. In particular, in the range indicated by reference numeral 603, all data in the cache memory 113 is written to the hard disk 114 by the flash command “f” 65. This flush command “f” 65 is for preventing overflow. Due to the effect, the length of the flash command control period 605 becomes shorter than the flash command control period 504 in the case of FIG.

  In FIG. 6C, the vertical axis represents the buffer memory occupation amount, and the horizontal axis represents time. A broken line 501 represents the maximum possible occupation amount (buffer memory threshold) of the buffer memory 105 as in FIG. That is, when the broken line 501 is exceeded, it is determined that the overflow has occurred. A solid line 602 indicates a buffer memory occupation amount curve.

  The tendency of the buffer memory occupancy curve 602 will be described. Since the period 605 shown in FIG. 6B is short, the buffer memory occupancy does not exceed the broken line 501. That is, the buffer memory occupation curve 502 shown in FIG. 5C has one large peak, whereas the buffer memory occupation curve 602 shown in FIG. 6C has two peaks. , Those peaks can be lowered. In other words, the size of the buffer memory 105 that temporarily stores data to be recorded in the hard disk drive 110 can be reduced.

  Next, an example of a processing flow for executing flash control (first flash control) for guaranteeing recording data and flash control (second flash control) for preventing overflow in this embodiment will be described with reference to FIG. One embodiment (first embodiment, second embodiment, and third embodiment) will be described with reference to FIGS.

  The first embodiment is a processing flow example of the first case described above. The second embodiment is a processing flow example of the second case described above. The third embodiment is a processing flow example in which the first and second embodiments are mixed.

(First embodiment)
FIG. 7 shows an example of a processing flow in the first embodiment (refer to FIGS. 1, 4A and 4B as appropriate).
In step S701, the control unit 104 acquires a write position in the management block. Specifically, when writing data to the hard disk 114, the control unit 104 designates and records the address, so that the writing position in the management block can be acquired from the address.

In step S702, the control unit 104 determines whether the writing position is within a predetermined range. Specifically, the predetermined range is the flash control time prediction period 404a in FIG. 4A or the flash control time prediction period 404b in FIG. 4B. The control unit 104 determines whether it is within a predetermined range using the address of the writing position.
If it is determined that it is within the predetermined range (Yes in step S702), the process proceeds to step S703. If it is determined that it is not within the predetermined range (No in step S702), the process proceeds to step S707.

  In step S703, the control unit 104 calculates the amount of video data per unit time recorded in the management block. Specifically, the control unit 104 calculates the amount of video data per unit time recorded in the management block based on, for example, the average value per unit time of the amount of video data output from the encoder 103 in the past. . Alternatively, the control unit 104 may calculate the amount of video data per unit time from the inclination characteristics of the write position line 402 shown in FIG.

  In step S704, the control unit 104 predicts the flash control time. Specifically, the control unit 104 uses the end address of the management block, the address of the current writing position, and the amount of video data per unit time as the writing position (the first position). The time of flash control) is calculated.

In step S <b> 705, the control unit 104 determines whether or not a difference absolute value of a plurality of predicted times is equal to or less than a threshold value. For example, in the case of FIG. 4A, the control unit 104 calculates the flash control predicted time as t3, and in the case of FIG. 4B, the flash control predicted time is calculated as t3. Since the absolute difference value is zero, it is determined that the difference is equal to or less than the threshold value. The threshold value may be set to the maximum value of the timing interval when the flash command is executed continuously.
When it is determined that the difference absolute value of the predicted time is equal to or less than the threshold (Yes in step S705), the process proceeds to step S706. When it is determined that the difference absolute value of the predicted time is larger than the threshold (No in step S705), the process is performed. The process returns to step S701.

  In step S706, the control unit 104 performs flash control a predetermined time before the predicted time. The predetermined time before is preferably set at a time separated from the flash control (first flash control) for guaranteeing the recording data so as not to be executed continuously. However, if the flash control is executed at a time far from the time when the flash control (first flash control) for guaranteeing the recording data is executed, the data is accumulated in the cache memory 113. It is preferable that the time of the flash control (first flash control) for guaranteeing the recording data is close to some extent. Note that after step S706, the process returns to step S701.

In step S707, the control unit 104 determines whether the write position is the end of the management block.
If it is determined that it is the end of the management block (Yes in step S707), the process proceeds to step S708. If it is determined that it is not the end of the management block (No in step S707), the process returns to step S701.

  In step S708, the control unit 104 executes flash control (first flash control). Then, the process returns to step S701.

(Second embodiment)
FIG. 8 shows an example of a processing flow in the second embodiment (see FIGS. 1 and 4C as appropriate).
In step S801, the control unit 104 acquires the current time. Specifically, the control unit 104 acquires the current time from a timer (not shown).

In step S802, the control unit 104 determines whether or not the current time is within a predetermined range. The predetermined range is the flash control time prediction period 405 in FIG.
If it is determined that it is within the predetermined range (Yes in step S802), the process proceeds to step S803. If it is determined that it is not within the predetermined range (No in step S802), the process proceeds to step S805.

In step S803, the control unit 104 determines whether or not the absolute difference value of the end time of another predetermined cycle is equal to or less than a threshold value. Specifically, when the end time of the flash control is t3 in the case of FIG. 4C, the control unit 104 determines whether or not the absolute value of the difference from the other end times is equal to or less than a threshold value. The threshold value may be set to the maximum value of the timing interval when the flash command is executed continuously.
If it is determined that the difference absolute value of the end time is equal to or less than the threshold (Yes in step S803), the process proceeds to step S804. If it is determined that the difference absolute value of the end time is greater than the threshold (No in step S803), the process is performed. The process returns to step S801.

  In step S804, the control unit 104 performs flash control a predetermined time before the end time. The predetermined time before is preferably set at a time separated from the flash control (first flash control) for guaranteeing the recording data so as not to be executed continuously. However, if the flash control is executed at a time far away from the time when the flash control for guaranteeing the recording data (first flash control) is executed, the data is accumulated in the cache memory 113. Therefore, it is preferable that it is close to a certain time to the flash control time (first flash control) for guaranteeing the recording data. Note that after step S804, the process returns to step S801.

In step S805, the control unit 104 determines whether it is an end time of a predetermined cycle.
If it is determined that it is the end time of the predetermined cycle (Yes in step S805), the process proceeds to step S806. If it is determined that it is not the end time of the predetermined period (No in step S805), the process returns to step S701. .

  In step S806, the control unit 104 executes flash control (first flash control). Then, the process returns to step S801.

(Third embodiment)
FIG. 9 shows an example of a processing flow in the third embodiment (see FIGS. 1, 4A, 4B, and 4C as appropriate). The third example is a processing flow example in which the first example and the second example are mixed. Accordingly, in the third embodiment, the same reference numerals as those in the first embodiment and the second embodiment represent the same processing, and the description thereof is omitted. Specifically, steps S701 to S708 are the same as the processing of the first embodiment. Steps S801, S802, S805, and S806 are the same as those in the second embodiment.

In the third embodiment, in step S901, the control unit 104 determines whether the processing target is control by a management block.
If it is determined that the control is based on the management block (Yes in step S901), the process proceeds to step S701. If it is determined that the control is not based on the management block (No in step S901), the process proceeds to step S801.

  In step S902, the control unit 104 sets the end time to the predicted time. This process is for matching the input data to step S705 of the first embodiment. In FIG. 9, after step S706, after step No in step S705, after step S708, after step No in step S805, and after step S806, the process returns to step S901.

  As described above, the monitoring recorder 100 of the present invention includes at least the encoder 103 that encodes the video signal of the camera 10 to generate video data, the buffer memory 105 that temporarily stores the video data, and the hard disk drive. And a control unit 104 that executes control for recording video data on the hard disk 114 via the HDD controller 106. The control unit 104 records video data on the hard disk 114 using flash control (first flash control) for guaranteeing recording data. At this time, if the flash control (first flash control) continues and the flash control period becomes longer, the buffer memory 105 overflows. In order to prevent the overflow, the control unit 10 executes a flash control (second flash control) for preventing an overflow of the buffer memory 105 before a predetermined time for executing the flash control for guaranteeing the recording data. It has. By providing such a configuration, the monitoring recorder 100 can reduce the size of the buffer memory 105 that temporarily stores data to be recorded in the hard disk drive 110.

  In the present embodiment, the recording area is described as being assigned to each camera 10, but one recording area may be assigned to a plurality of cameras 10.

In addition, this invention is not limited to above-described embodiment, Various modifications are included. For example, the above-described embodiment has been described in detail for easy understanding of the present invention, and is not necessarily limited to one having all the configurations described. Further, a part of the configuration of an embodiment can be replaced with the configuration of another modification, and the configuration of another modification can be added to the configuration of an embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of the embodiment.
Further, each function or the like of the monitoring recorder 100 may be realized by hardware by designing a part or all of them, for example, by an integrated circuit. The functions of the control unit 104 may be realized by software by interpreting and executing a program that realizes each function by the processor. Information such as programs, tables, and files for realizing each function is stored in a memory, a recording device such as a hard disk or SSD (Solid State Drive), or a recording medium such as an IC card, SD card, or DVD (Digital Versatile Disc). be able to.
In addition, the control lines and information lines are those that are considered necessary for the explanation, and not all the control lines and information lines on the product are necessarily shown. In practice, it may be considered that almost all configurations are connected to each other.

10 Camera 100 Recorder for monitoring 101 A / D
102 MIX
103 Encoder 104 Control Unit 105 Buffer Memory 106 HDD Controller 110 Hard Disk Drive 111 I / F
112 Controller 113 Cache memory 114 Hard disk 401a, 401b End of management block 402, 403 Write position line 404a, 404b, 405 Flash control time prediction period 501 Buffer memory threshold 502, 602 Buffer memory occupation curve 504, 603, 605 Flash command control period

Claims (12)

An encoder that encodes the video signal of the camera to generate video data;
A buffer memory for temporarily storing the video data;
A control unit that executes control for recording video data read from the buffer memory at a specified address of a hard disk of a hard disk drive;
With
The control unit records the video data on the hard disk by a first flash control for guaranteeing the recorded data using a flash command, and at a predetermined time before executing the first flash control, A monitoring recorder that executes second flash control different from the first flash control. The monitoring recorder according to claim 1, wherein the control unit executes the first flash control for each management block having a predetermined size of the hard disk as a unit. If there are multiple areas recorded on the hard disk depending on the camera,
For each area, the control unit determines the time of the first flash control corresponding to the area based on the amount of the video data generated by the encoder, the address to be written to the hard disk, and the size of the management block. When the difference absolute value between the predicted time of the first flash control and the time of the other first flash control is less than or equal to a preset threshold value, 3. The monitoring recorder according to claim 2, wherein the second flash control is executed before a predetermined time before the first flash control is executed. The monitoring recorder according to claim 1, wherein the control unit executes the first flash control at predetermined intervals. If there are multiple areas recorded on the hard disk depending on the camera,
The control unit predicts, for each area, the time of the first flash control corresponding to the area based on the end time of the predetermined cycle, and the time of the predicted first flash control and others. It is determined whether or not a difference absolute value with respect to the time of the first flash control is equal to or less than a preset threshold value. When it is determined that the difference is equal to or less than the threshold value, the predetermined flash time before executing the first flash control is The monitoring recorder according to claim 4, wherein the second flash control is executed. 2. The monitoring recorder according to claim 1, wherein the predetermined time is a length of a period that satisfies that the first flash control and the second flash control are not continuous. An encoder that encodes the video signal of the camera to generate video data, a buffer memory that temporarily stores the video data, and a control that records the video data read from the buffer memory at a specified address on the hard disk of the hard disk drive And a data recording method for a monitoring recorder comprising:
The controller is
Recording the video data on the hard disk by a first flash control for guaranteeing the recorded data using a flash command;
And a step of performing a second flash control different from the first flash control before a predetermined time for executing the first flash control. The data recording method according to claim 7, wherein the control unit executes the first flash control for each management block having a predetermined size of the hard disk as a unit. If there are multiple areas recorded on the hard disk depending on the camera,
For each area, the control unit determines the time of the first flash control corresponding to the area based on the amount of the video data generated by the encoder, the address to be written to the hard disk, and the size of the management block. When the difference absolute value between the predicted time of the first flash control and the time of the other first flash control is less than or equal to a preset threshold value, 9. The data recording method according to claim 8, wherein the second flash control is executed a predetermined time before the first flash control is executed. 8. The data recording method according to claim 7, wherein the control unit executes the first flash control at predetermined intervals. If there are multiple areas recorded on the hard disk depending on the camera,
The control unit predicts, for each area, the time of the first flash control corresponding to the area based on the end time of the predetermined cycle, and the time of the predicted first flash control and others. It is determined whether or not a difference absolute value with respect to the time of the first flash control is equal to or less than a preset threshold value. When it is determined that the difference is equal to or less than the threshold value, the predetermined flash time before executing the first flash control is The data recording method according to claim 10, wherein the second flash control is executed. The data recording method according to claim 7, wherein the predetermined time is a length of a period that satisfies that the first flash control and the second flash control are not continuous.

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