JP5299462B2 - Video data storage device and video data storage method - Google Patents

Description

  The present invention relates to an apparatus and method for storing video data.

  As is well known, there is a case where a remote monitoring system is constructed using an existing communication infrastructure. In this case, a monitoring camera is installed at each monitoring point, and these monitoring cameras are connected to a head office monitor and a computer through an encoder, a communication infrastructure, and a decoder in this order. The video data generated by the surveillance camera is converted into a format according to the communication protocol by the encoder and sent to the decoder. The monitor or computer displays video based on the video data passed from the decoder or stores it in the database. Or

  By the way, high communication speed may not be obtained depending on the existing communication infrastructure. In this case, if an operation mode is employed in which video data is constantly transmitted from all surveillance cameras to the computer at the headquarters, traffic is concentrated and a congestion state occurs. For this reason, some remote monitoring systems do not transmit video data in a normal state, but store them in a local storage device, and if some event occurs, they go back a predetermined time from the time of occurrence. There is an operation form in which video data up to a point in time is transmitted to a computer at the headquarters. According to this operation mode, a remote monitoring system can be constructed without imposing a load on the network.

JP 2001-339677 A Japanese Patent No. 2807456

In the operation mode in which the network load is suppressed as described above, the storage device for storing the video data of the surveillance camera may be a device for recording data on an endless video cassette tape, a HDD [Hard A device that records to [Disk Drive] is employed.

  However, endless tapes have problems in durability, such as deterioration in image quality due to continuous use, stretching of the tape itself, and backlash of movable parts due to continuous driving. For this reason, the administrator had to frequently go to various places and change the endless tape.

  On the other hand, some HDDs are very expensive and are guaranteed to be continuously driven 24 hours a day. However, since the HDD is a precision device, there is a problem that operation failure occurs depending on the installation environment such as temperature, vibration, and dust regardless of the price. For this reason, even if the administrator uses the existing communication infrastructure to reduce the cost of laying the network, the administrator has to spend a great deal of money to install the HDD in a special environment that is equipped with air conditioning equipment. It was.

  The present invention has been made in view of the problems of the prior art as described above, and the problem is that the portion of video data continuously generated by the camera from the time of recording to a predetermined time before is recorded locally. In the case of adopting a storage operation mode, it is not necessary to frequently exchange recording media, and to prevent malfunction due to the installation environment.

  The disclosed video data storage apparatus employs the following means in order to solve the above-described problems.

That is, the first aspect is
A video data storage device comprising a flash memory and an SDRAM,
A partition definition unit for defining a plurality of partitions having the same capacity on the storage area by equally partitioning the entire storage area of the storage medium including the flash memory;
A storage unit for adding time information to the image data and writing it to a section storing the oldest image data in the storage area each time image data constituting video data is input; and
Each time the storage unit writes image data in any partition, the time information written in the partition is associated with information indicating the location of the partition in the storage area and stored in the SDRAM A video data storage device comprising a unit.

  According to the disclosed apparatus, it is not necessary to frequently change the recording medium in the case of adopting an operation mode in which a portion of video data continuously generated by the camera is stored on site from a recording time to a predetermined time before. Moreover, the malfunction due to the installation environment is prevented.

Configuration diagram of remote monitoring system of this embodiment Configuration diagram of video data transmitter Explanatory drawing which shows the method of recording video data in the 1st and 2nd storage area The figure which shows the storage state of the image data to the 2nd storage area before (a) abnormality detection and (b) after abnormality detection.

  Next, the best mode for carrying out the present invention will be described in detail with reference to the accompanying drawings.

  First, the configuration of the remote monitoring system of this embodiment will be described.

  FIG. 1 is a configuration diagram of a remote monitoring system according to the present embodiment.

  As shown in FIG. 1, the remote monitoring system according to the present embodiment includes at least one set of monitoring camera 10, anomaly detection sensor 20 and video data transmitting device 30, and at least one set of video data receiving device 40 and monitor 50. Consists of.

  The monitoring camera 10 is a device that shoots a monitoring target and generates video data. The monitoring camera 10 is installed on a utility pole, a house root, or a wall with a visual field facing the monitoring target.

  The abnormality detection sensor 20 is a sensor for detecting that an abnormality has occurred in the monitoring target. Specific examples include so-called infrared sensors and phototube measuring instruments. The infrared sensor is a sensor that outputs a signal that an abnormality has occurred when the infrared ray that has exited from the light emitting element and entered the light receiving element is blocked by an intruder. The phototube measuring device is a sensor that outputs a signal that an abnormality has occurred when the infrared ray that has exited from the light emitting / receiving element, reflected by the reflecting plate, and returned to the light emitting / receiving element is blocked by an intruder.

The video data transmitting device 30 performs appropriate processing on the video data generated by the surveillance camera 10 and stores it for a certain period, and stores it when there is a request from a terminal device (not shown) on the IP [Internet Protocol] network. The video data is converted into a communication form according to the communication protocol of the IP network and transmitted to the video data receiving device 40. The configuration of the video data transmission device 30 will be described later. The video data transmitting device 30 is installed in a predetermined housing so as not to be exposed to wind and rain or dust.

  The video data receiving device 40 is a device that appropriately processes the video data received from the video data transmitting device 30 via the IP network and outputs the processed video data to the monitor 50.

  The monitor 50 is a device that displays video based on video data input from the video data receiving device 40.

  Next, the configuration of the video data transmission device 30 will be described.

  FIG. 2 is a configuration diagram of the video data transmission device 30.

As shown in FIG. 2, the video data transmitting apparatus 30 includes a flash ROM [Read Only Memory] 30a, a CPU [Central Processing Unit] 30b, and an SDRAM [Synchronous].
Dynamic Random Access Memory] 30c, input interface 30d, AD [Analogue Digital] converter 30e, MPEG-4 [Moving Picture Expert Group 4] video encoder 30f, MPEG-2 video encoder 30g, LAN [Local Area Network] controller 30h, PC [Personal Computer] A card controller 30i is incorporated.

  The flash ROM 30a is a read-only storage device that stores various programs and various data necessary for performing the functions of the device 30. The CPU 30a is a control unit that performs processing according to a program in the flash ROM 30a. The SDRAM 30c is a readable / writable storage device in which a work area of the CPU 30b is expanded. When receiving an abnormality occurrence signal from the abnormality detection sensor 20, the input interface 30d is an interface that notifies the CPU 30b of that fact.

  The AD converter 30e is a converter that converts video data generated by the surveillance camera 10 from analog data to digital data. The MPEG-4 video encoder 30f is a compressor that compresses video data converted into analog data by the AD converter 30e in accordance with the MPEG-4 standard. The MPEG-2 video encoder 30g is a compressor that compresses video data converted into analog data by the AD converter 30e in accordance with the MPEG-2 standard.

  The LAN controller 30h is an interface for transmitting / receiving data to / from a relay device such as a router in the IP network. The PC card controller 30i has a slot on which an expansion card called a PC card (trademark of the Japan Electronics Industry Promotion Association and the American PC Memory Card International Association) can be detachably mounted, and the PC card can be used according to its function. It is an interface for operating as a memory card adapter, a wireless LAN interface, and a PHS [Personal Handyphone System] data card.

In this embodiment, a memory card 31 containing a flash memory is mounted on the PC card controller 30i through a memory card adapter type PC card. Of course, the present invention is not limited to the memory card 31 and, for example, a PC card incorporating a flash memory may be attached to the PC card controller 30i. In short, anything that incorporates flash memory with no moving parts is acceptable.

As the memory card 31 incorporating the flash memory, for example, an SD [Secure Digital] card (Toshiba Corporation, Matsushita Electric Industrial Co., Ltd. and SanDisk Corporation, USA), CompactFlash (U.S. SanDisk Corporation), Memory Stick (Trademark of Sony Corporation), smart media (trademark of Toshiba Corporation), and xD [eXtreme Digital] picture card (trademark of Fuji Photo Film Co., Ltd. and Olympus Optical Co., Ltd.).

  In the video data transmitting apparatus 30 configured as described above, the storage area of the flash memory of the memory card 31 includes the first storage area 31a in which the video data output from the MPEG-4 video encoder 30f is recorded, and the MPEG. -2 is divided into a second storage area 31b in which video data output from the video encoder 30g is recorded.

  The video data output from the MPEG-4 video encoder 30f is always recorded in the first storage area 31a and output from the MPEG-2 video encoder 30g by a file system function based on a predetermined program in the flash ROM 30a. The video data to be recorded is always recorded in the second storage area 31b.

  However, this file system function of the present embodiment records video data in the first and second storage areas 31a and 31b by a method different from the conventional file system function such as FAT [File Allocation Table]. .

  FIG. 3 is an explanatory diagram showing a method of recording video data in the first and second storage areas 31a and 31b.

  FIG. 3 shows one of the first and second storage areas 31a and 31b. As shown in FIG. 3, the first and second storage areas 31a and 31b are shown. All are equally divided into sections of the same capacity and managed. The capacity of one section is equal to the sum of the size of the image data constituting the video data and the size of the header information for managing the image data. The header information includes at least time information indicating the time when storage of the image data in one section is started.

  Therefore, the file system function for managing the storage area by dividing it into a plurality of partitions corresponds to the partition definition unit described above.

  Each partition in one storage area is defined in order as shown by 1, 2,..., N-1, N in FIG. One is stored for each partition in order from the first partition to the last partition. When the image data is stored up to the last section, the next image data is overwritten with the image data in the first section, and the subsequent image data is the image data in each section according to the order of each section. Is overwritten (cyclic). In other words, by overwriting in order from the old image data, N image data from the recording time of the image data to a time point that is a predetermined time back in spite of the sequential recording of the image data in this storage area. Will always be stored temporarily.

  When image data is stored in any of the sections, time information indicating the storage start time is included in the header information of the image data and is recorded in the same section together with the image data.

  Therefore, the file system function for sequentially writing image data to each partition corresponds to the storage unit described above.

  Further, when image data is stored in any partition of the storage area, time information indicating the storage start time and information indicating the head sector address in the partition are sent to the SDRAM 30c. The SDRAM 30c is provided with two data management tables 32 for storing time information and head sector address information in association with each other, and each time image data is stored in the first storage area 31a, the image information is stored. The time information and head sector address information about the image data is stored in the first data management table 32a and the image data is stored in the second storage area 31b. Information is stored in the second data management table 32b. Of course, when the image data is overwritten on the image data already stored in any of the partitions, the time information and the head sector address information about the image data are stored in the data management tables 32a and 32b. The time information and head sector address information of the image data based on

  Therefore, the file system function for recording the time information and the head sector address information in the first and second data management tables 32a and 32b in the SDRAM 30c corresponds to the storage unit described above.

  Since the first and second data management tables 32a and 32b are generated on the SDRAM 30c, they disappear from the SDRAM 30c when the main power supply of the video data transmitting device 30 is cut off. For this reason, the flash ROM 30a of the video data transmission device 30 has a header for each section of the first and second storage areas 31a and 32b of the memory card 31 when the main power of the video data transmission device 30 is turned on. A program for reading the information and the head sector address information and causing the CPU 30b to perform processing for generating the first and second data management tables 32a and 32b on the SDRAM 30c is stored.

  By the way, if data recorded in the flash memory in the memory card 31 is to be managed by a general file system function such as FAT, data such as a FAT area in the FAT file system is managed in the flash memory. An area in which information for recording is recorded is secured. The general file system updates information in the area every time data is recorded on the memory card 31. However, the flash memory has an upper limit of the number of times the internal storage element can be rewritten (overwritten). For this reason, if the image data is continuously recorded in the flash memory 24 hours a day, the number of times the data management information recording area is rewritten before the image data recording area reaches the upper limit. The upper limit was reached fairly early, and the flash memory had reached the end of its life before the image data recording area was used up.

  On the other hand, according to the present embodiment, as described above, since the first and second data management tables 32a and 32b are generated on the SDRAM 30c, the first and second data management tables 32a and 32b are stored in the first and second data management tables 32a and 32b. Even if access is frequent, the number of rewrites of the first and second storage areas 31a and 31b increases uniformly, so the flash memory does not reach the end of its life early and is used up when it reaches the end of its life. There is no territory.

Here, the upper limit of the number of rewrites of the internal storage element of the flash memory is Wt [times], the storage capacity of the storage area of the flash memory is S [bit], and the video encoder 30f,
When the encoding rate of 30 g is R [bit / second], the flash memory rewrite life is
It can be expressed as {Wt × (S / R)} [seconds].

  In the present embodiment, a state switching function not provided in the first storage area 31a is added to the second storage area 31b. Specifically, when an abnormality is detected by the abnormality detection sensor 20 in a state where the image data constituting the video data from the MPEG-2 video encoder 30g is sequentially stored in the second storage area 31b, this state The switching function sets the image data stored in the second storage area 31b from the time when the abnormality is detected to a predetermined time before being overwritten. This function is also based on the program in the flash ROM 30a.

  FIG. 4 is an explanatory diagram showing a video data storage method when an abnormality is detected. 4A shows the storage state of the image data in the second storage area 31b before the abnormality detection sensor 20 detects an abnormality. FIG. The storage state of the image data in the second storage area 31b after the abnormality is detected is shown.

  As shown in FIG. 4A, before the abnormality detection sensor 20 detects an abnormality, the image data of any section is temporarily stored and then updated by overwriting. On the other hand, after the abnormality detection sensor 20 detects an abnormality, as shown in FIG. 4B, all the image data stored until a predetermined time from when the abnormality detection sensor detects the abnormality Overwriting is prohibited, and the file system function of this embodiment stores image data in the remaining partitions other than the partition in which the image data for which overwrite is prohibited is stored. Of the sections shown in FIG. 4B, a section whose upper right corner is painted black means a section where overwriting of image data is prohibited.

  More specifically, the header information of the image data stored in each section of the second storage area 31b includes write prohibition flag information in addition to time information. When the abnormality detection sensor 20 issues an abnormality detection signal, the state switching function described above can write the write prohibition flag information of a predetermined number (for example, three) of image data stored immediately before that point. Switch from state to write-disabled state.

  On the other hand, the file system function of the present embodiment described above, when trying to write image data to each partition of the second storage area 31b (when attempting to overwrite and update the image data in each partition), The write prohibition flag information included in the header information is read to confirm whether it is in a writable state or a writable state. If the file system function is in a writable state, the image data is written to the partition. If the file system function is not writable, the file system function is in a writable state in accordance with the order assigned to each partition. Find the existing section, and write the image data after the found section.

  Since it is configured in this manner, as shown by the arrow in FIG. 4B, the unwritable section is avoided, and the other sections are used as image data write targets.

  Therefore, the state switching function corresponds to the state switching unit described above.

  Next, the life of the memory card 31 in this embodiment will be described.

  For example, a case will be described in which the memory card 31 having a total capacity of 8 GB and an upper limit Wt of rewritable times of 100,000 is used. In this case, in the present embodiment, 4 GB of the total capacity is allocated to the first storage area 31a and the remaining 4 GB is allocated to the second storage area 31b.

When the size of an image generated by the MPEG-4 video encoder 30f is 360p × 240p and the image encoding rate (output speed) is 350K [bit / second], the entire capacity of the first storage area 31a Since S is 4 GB = 32768 G [bit], the first
The round rewriting time (S / R) required to rewrite all the image data stored in the storage area 31a is 32768 / 0.35 = 93623 [seconds] = 26 [hours]. Further, the rewrite life {Wt × (S / R)} of the entire first storage area 31a is 100000 × 26 = 2600000 [hour] ≈296 [year].

When the size of the image generated by the MPEG-2 video encoder 30g is 720p × 480p and the image encoding rate is 3M [bit / second], the second storage area 3
Since the total capacity S of 1b is also 4 GB = 32768 G [bit], the round rewriting time (S / R) required to rewrite all the image data stored in the second storage area 31b is 32768/3 = 10923 [seconds] = 3 [time]. The rewrite life {Wt × (S / R)} of the entire second storage area 31b is 100000 × 3 = 300000 [hours] ≈34 [years].

  In the second storage area 31b, when the image data for 2 hours is prohibited from being overwritten, the one-time rewrite time (S / R) is 3-2 = 1 [hour]. Is maintained, the rewrite life {Wt × (S / R)} of the second storage area 31b is 100,000 [hours] = 11 [years].

  As described above, the compressed video data generated at a low rate by the MPEG-4 video encoder 30f and the compressed video data generated at a high rate by the MPEG-2 video encoder 30g are both continuously open 24 hours a day. Even if the data is written in the memory card 31, the lifetime of 10 years or more is guaranteed.

  Further, the round rewriting time (S / R) of the first storage area 31a is 24 hours or more, and the round rewriting time (S / R) of the second storage area 31b is 2 hours or more.

  Next, the operation and effect of the video data transmitting apparatus 30 of this embodiment will be described.

  When video data is input from the surveillance camera 10, the video data transmitting apparatus 30 according to the present embodiment performs digital conversion and then compresses video data generated at a low rate by the MPEG-4 video encoder 30 f and MPEG-2. The compressed video data generated at a high rate by the video encoder 30g is written into the first and second storage areas 31a and 31b of the memory card 31.

  Then, before the abnormality detection sensor 20 detects an abnormality, as described above, in the first storage area 31a and the second storage area 31b, the image data is recorded while being overwritten in order from the old image data. N pieces of image data up to a point in time after a predetermined time are always temporarily stored.

  When the abnormality detection sensor 20 detects an abnormality, the predetermined number of partitions in which the image data is written immediately before the abnormality detection time among the partitions in the second storage area 31b are prohibited from being written. Will be written to the remaining partitions. Then, some image data that has been stored without being overwritten in the write-protected section is provided to other computers on the IP network through the LAN controller 30h, or the installation location of the video data transmitting apparatus 30 It is collected by the manager who has visited.

  Since the image data collected in this way is compressed by the MPEG-2 video encoder 30g, for example, characters on a license plate of a car are read, and a person's outline, facial expression, facial expression, etc. are read. Such a high-quality image can be displayed on the display device. Therefore, the situation when an abnormality occurs in the monitoring target of the monitoring camera 10 can be verified in detail.

  On the other hand, even if the abnormality detection sensor 20 detects an abnormality, the writing of the image data is continued in all the sections of the first storage area 31a. Since this image data is compressed by the MPEG-4 video encoder 30f, the image quality is not so good compared to the image compressed by MPEG-2, but the shape and posture of people and cars are grasped. It has become something that can be done. Accordingly, when an abnormality occurs, the video data remaining in the first storage area 31a is reproduced on the monitor 50 through the IP network and the video data receiving device 40 or stored in a computer (not shown). Or by moving to the place where the video data transmitting device 30 is installed and collecting it, it is possible to verify the movement of a person or a vehicle. Further, in the above example, the round rewriting time is 26 hours, so that it is not necessary to quickly collect video data after an abnormality occurs.

  As described above, according to the present embodiment, since each image data is written on the average in the storage area of the memory card 31 without being biased, the storage is performed when a part of the storage area reaches the upper limit of the number of times of writing. There is no end to life without using up all the media. As a result, the storage medium need not be frequently replaced.

Further, since the memory card 31 is made of a flash memory, it does not have a movable part like an HDD [Hard Disk Drive]. For this reason, there is no backlash of the movable part due to non-stop driving, and there is no malfunction due to the installation environment.

  Furthermore, as in this embodiment, by recording on the memory card 31 together with low rate (low image quality) image data and high rate (high image quality) image data, the video can be stored (recorded) for a long time and verified. It will be possible to save high-quality images that can withstand.

(Appendix 1)
A partition definition unit that defines a plurality of partitions having the same capacity on the storage area by partitioning the entire storage area of the storage medium including the flash memory;
A storage unit for adding time information to the image data and writing it to a section storing the oldest image data in the storage area each time image data constituting video data is input; and
Each time the storage unit writes image data in any partition, the storage unit stores time information written in the partition and information indicating the location of the partition in the storage area in association with each other. A video data storage device.

(Appendix 2)
When the storage of the image data is instructed, it further includes a state switching unit that sets the predetermined number of sections in which the image data is written immediately before the instructed time point to a state in which the image data cannot be written,
The storage unit writes the image data in a partition in which the oldest image data is stored among the remaining partitions except the partition in which the image data cannot be written when the image data is written in any of the partitions. The video data storage device according to appendix 1, wherein

(Appendix 3)
When the image data is written in any of the sections, the storage unit adds flag information indicating that the image data may be overwritten together with time information, and adds the image data to which the information is added. Write to the partition where the oldest image data is stored among the remaining partitions except the partition where the flag information indicating that overwriting is prohibited is written,
The state switching unit, when instructed to save image data, from a state indicating that the flag information of a predetermined number of sections in which the image data was written immediately before the instructed time point may be overwritten, The video data storage device according to appendix 2, wherein the video data storage device is switched to a state indicating that overwriting is prohibited.

(Appendix 4)
When a request is instructed from any of the terminal devices via the network, the image processing apparatus further includes a transmission unit that transmits image data stored in a partition where image data cannot be written to the terminal device. The video data storage device according to attachment 1.

(Appendix 5)
By equally dividing the entire storage area of the storage medium consisting of flash memory, a plurality of partitions having the same capacity are defined on the storage area,
Each time image data constituting video data is input, time information is added to the image data and written to a section in the storage area where the oldest image data is stored,
Video data characterized in that each time image data is written in any of the sections, the time information written in that section and information indicating the location of the section in the storage area are stored in association with each other Storage method.

(Appendix 6)
Computer
Partition defining means for partitioning all storage areas of a storage medium comprising a flash memory to define a plurality of partitions having the same capacity on the storage area;
Storage means for adding time information to the image data and writing it to a section storing the oldest image data in the storage area each time image data constituting video data is input; and
Each time the storage means writes image data in any partition, the time information written in that partition is associated with information indicating the location of the partition in the storage area and stored in the storage device A video data storage program characterized by functioning as a means.

DESCRIPTION OF SYMBOLS 10 Surveillance camera 20 Abnormality detection sensor 30 Video data transmitter 30c SDRAM
30f MPEG-4 video encoder 30g MPEG-2 video encoder 30i PC card controller 40 Video data receiver 50 Monitor

Claims (3)

A video data storage device comprising a flash memory and an SDRAM,
A partition definition unit for defining a plurality of partitions having the same capacity on the storage area by equally partitioning the entire storage area of the storage medium including the flash memory;
A storage unit that adds time information to image data and writes it to a section storing the oldest image data in the storage area each time image data constituting video data is input ,
Each time the storage unit writes image data in any partition, the time information written in the partition is associated with information indicating the location of the partition in the storage area and stored in the SDRAM Part and
A state switching unit that, when instructed to store image data, sets a predetermined number of sections in which image data is written immediately before the instructed time point to a state in which image data cannot be written;
The storage unit writes the image data in a partition in which the oldest image data is stored among the remaining partitions except the partition in which the image data cannot be written when the image data is written in any of the partitions. <br/> A video data storage device characterized by the above. When the image data is written in any of the sections, the storage unit adds flag information indicating that the image data may be overwritten together with time information, and adds the image data to which the information is added. Write to the partition where the oldest image data is stored among the remaining partitions except the partition where the flag information indicating that overwriting is prohibited is written,
The state switching unit, when instructed to save image data, from a state indicating that the flag information of a predetermined number of sections in which the image data was written immediately before the instructed time point may be overwritten, 2. The video data storage device according to claim 1 , wherein the video data storage device is switched to a state indicating that overwriting is prohibited. A video data storage method for a video data storage device comprising a flash memory and an SDRAM,
By equally dividing the entire storage area of the storage medium composed of the flash memory, a plurality of partitions having the same capacity are defined on the storage area.
Each time the data constituting the video data is input, time information is added to the data and written to the section where the oldest data in the storage area is stored,
Each time data is written in any of the partitions, the time information written in the partition is associated with information indicating the location of the partition in the storage area and stored in the SDRAM ,
When storage of image data is instructed, a predetermined number of sections in which image data has been written immediately before the instructed time point are set in a state in which image data cannot be written,
When writing image data to any of the partitions, write the image data to the partition where the oldest image data is stored among the remaining partitions except the partition where image data cannot be written. <br/> A video data storage method characterized by.

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