JP2013196330A - Drive recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drive recorder for preventing alternation of video data.SOLUTION: The driver includes: a camera (12); an image processing part (140); a voice control part (190); a recording control part (150); and a control part (160). The control part (160) generates recording position information (205) showing the recording position of a unit image in video data in the case of making the recording control part (150) record the video data in a memory card (30), and encrypts the generated recording position information (205) and an area including the leading section of the unit image, and makes the recording control part (150) record the encrypted video data.

Description

  The present invention relates to a drive recorder that is mounted on a vehicle and records video data.

  A drive recorder that records driving data of a vehicle together with video data is mounted on the vehicle. For example, when an impact occurs in the vehicle, the drive recorder is configured to acquire video data for a predetermined time before and after the time when the impact occurred and to record the data in a memory card.

  The video data recorded by the drive recorder is evidence of the cause of the vehicle accident, and requires data reliability and identity. For this reason, measures such as encryption are generally taken to prevent tampering.

  Patent Document 1 discloses a data encryption method for encrypting encoded information (Huffman table or quantization table) included in header information of JPEG data using a pre-registered encryption key.

JP 2007-208931 A

  An MPEG4 format moving image compression format is known as a recording format for moving image information. The MPEG4 format is a moving image format recorded by inter-frame compression, but even if it tries to extract still image data that is a single frame from the moving image, this compression method reduces the sharpness of the still image data, Evidence is inferior.

  An image compression standard called motion JPEG format is also known. The motion JPEG format is a continuous recording of JPEG format image data, and does not perform compression between frames. Therefore, since the sharpness when extracting still image data which is a single frame from video data is higher than that of the MPEG4 format, the evidence capability is increased.

  However, since the motion JPEG method does not perform inter-frame compression, the file size of the recorded video data is larger than that of the MPEG method. Therefore, when video data recorded by the motion JPEG method is encrypted, there is a problem that the processing load for encryption becomes large.

  Here, for each JPEG format image included in the motion JPEG, the processing load can be reduced by encrypting only the header information as described in Patent Document 1 described above.

  However, when only predetermined information such as header information is encrypted with the encryption key, the encrypted data becomes a fixed pattern, and the encrypted portion is easily discriminated by a third party, and the video data is altered. There was a problem of fear.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a drive recorder that can reduce the processing load of video data encryption and prevent falsification of video data in the drive recorder. To do.

  The present invention is mounted on a vehicle and is generated by a camera that acquires a video signal, an image processing unit that encodes the video signal acquired by the camera to generate video data that is a set of unit images, and an image processing unit. A recording control unit that controls the recording of the video data, and a control unit that controls the image processing unit and the recording control unit. When the video data is recorded by the recording control unit, the control unit is a unit in the video data. The recording position information indicating the recording position of the image is generated, the generated recording position information is encrypted, the header area of the unit image and a part of the data area are encrypted, and the encrypted recording position information and the unit image are encrypted. The video data including is recorded by the recording control unit.

  According to the present invention, when video data is recorded by the recording control unit, the recording position information indicating the recording position of the unit image is generated, and the area including the recording position information, the header information of the unit image, and part of the data area And encrypt. By such processing, processing becomes easier than encrypting the entire video data, and the processing load for encryption can be reduced. In addition, since the area including the head part of the unit image is encrypted, it becomes difficult for a third party to determine the encrypted part, and alteration of the video data can be prevented.

It is explanatory drawing of the drive recorder system containing the drive recorder of embodiment of this invention. It is a functional block diagram of the drive recorder of the embodiment of the present invention. It is explanatory drawing which shows the recording process of the video data and audio | voice data of embodiment of this invention. It is explanatory drawing of the encryption process of the unit video data of embodiment of this invention. It is a flowchart of the recording process of the video data and audio | voice data of embodiment of this invention. It is explanatory drawing of the encryption process of the unit video data of another embodiment of this invention. It is explanatory drawing of the encryption process of the unit video data of further another embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is an explanatory diagram of a drive recorder system 1 including a drive recorder 10 according to an embodiment of the present invention.

  The drive recorder system 1 includes a drive recorder 10 mounted on a vehicle 11, a personal computer (hereinafter referred to as “PC”) 20 installed in an office, etc., and a memory card that records data acquired by the drive recorder 10. 30.

  The drive recorder 10 acquires travel data (for example, vehicle speed, engine speed, latitude, longitude, etc.) from the vehicle 11, and records these at predetermined time intervals together with date / time information. In addition, a camera 12 is connected to the drive recorder 10, and video data acquired by the camera 12 is recorded. In addition, a microphone 192 is connected to the drive recorder 10, and audio data acquired by the microphone 192 is recorded. The travel data, video data, and audio data are recorded on the memory card 30 via the recording control unit 150.

  The drive recorder 10 includes a recording control unit 150 that writes and reads data to and from the memory card 30 with the memory card 30 inserted, and a recording button 180 that artificially records video data on the memory card 30. And an LED 193 for displaying the state of the drive recorder 10 according to the lighting state (color, blinking, etc.).

  The PC 20 includes a memory card interface 21 that writes data to and reads data from the memory card 30 with the memory card 30 inserted, a display unit 22 that includes a liquid crystal display that can display video data, and the like. And an input unit 23 composed of a keyboard and a mouse capable of inputting instructions.

  The memory card 30 is configured to be readable and writable by the recording control unit 150 and the memory card interface 21. For example, a flash memory card such as SD (Secure Digital) or CF (Compact Flash (registered trademark)) is used.

  FIG. 2 is a functional block diagram of the drive recorder 10 according to the embodiment of the present invention.

  The drive recorder 10 includes an image processing unit 140, an internal memory 130, a recording control unit 150, a control unit 160, an acceleration sensor 170, a recording button 180, a sound control unit 190, and a power control unit 200. Prepare. The control unit 160 is connected to the image processing unit 140, the internal memory 130, the recording control unit 150, the acceleration sensor 170, the recording button 180, the voice control unit 190, and the power supply control unit 200, and controls these units. The control unit 160 is connected to the LED 193 and outputs a signal for controlling the lighting state of the LED 193. The control unit 160 is connected to the flash ROM 120 and controls reading of data recorded in the flash ROM 120.

  The image processing unit 140 performs image processing on the video signal received from the camera 12 based on a predetermined encoding method. The internal memory 130 temporarily records the video data encoded by the image processing unit 140. The recording control unit 150 records the video data on the memory card 30 inserted in the recording control unit 150.

  In the present embodiment, the image processing unit 140 encodes video data as a unit image in the JPEG format every predetermined time unit, and the motion JPEG format (M -JPEG format) video data.

  The internal memory 130 includes a buffer area composed of a volatile memory such as SDRAM, and is used as a buffer for temporarily recording video data when video data is recorded on the memory card 30 under the control of the control unit 160.

  The flash ROM 120 is composed of a non-volatile memory such as a flash memory, and is configured to retain recorded data even after the power supplied to the drive recorder 10 is cut off and the operation of the drive recorder 10 is stopped. Has been. The flash ROM 120 records programs and setting data related to the operation of the drive recorder.

  The acceleration sensor 170 detects the acceleration applied to the vehicle 11, and notifies the control unit 160 of the detection of the occurrence of an event when the detected acceleration exceeds a predetermined threshold. Regardless of whether the acceleration sensor 170 detects the occurrence of an event, the recording button 180 notifies the occurrence of the event to the control unit 160 when operated by the driver. The control unit 160 determines that an event such as an impact has occurred in the vehicle 11 when the event is detected from the acceleration sensor 170 or when the event is detected by operating the recording button 180 by the driver. Then, the video data recorded within a predetermined time before and after the event occurrence time is extracted from the buffer area of the internal memory 130. The extracted video data is recorded on the memory card 30 via the recording control unit 150.

  The voice control unit 190 controls voice recording and playback. A speaker 191 and a microphone 192 are connected to the audio control unit 190. Under the control of the control unit 160, the audio control unit 190 acquires audio around the drive recorder 10 with the microphone 192 when video data is being recorded, and records the acquired audio data in the internal memory 130. In addition, the voice control unit 190 operates a voice or a warning sound related to the operation of the drive recorder 10 (for example, a warning sound that the memory card 30 is not inserted) through the speaker 191 under the control of the control unit 160. The person in charge.

  The audio data recorded by the audio control unit 190 is sampled and quantized by, for example, a linear PCM (LPCM) method. The linear PCM method is a recording format in which the recording time from the beginning changes in accordance with the number of bits (offset) from the beginning of the audio data because the amount of audio data to be recorded is fixed.

  The power control unit 200 receives power from the vehicle 11 and supplies power to each unit via the control unit 160 and the control unit 160. The power supply control unit 200 has a built-in battery, and is configured to supply power to the control unit 160 and each unit for a certain period of time even when the supply of power from the vehicle 11 is cut off.

  Next, the operation of the drive recorder 10 configured as described above will be described.

  FIG. 3 is an explanatory diagram illustrating recording processing of the video data 201 and the audio data 210 executed by the control unit 160 according to the present embodiment.

  The video signal acquired by the camera 12 is encoded in a predetermined encoding method (JPEG format) by the image processing unit 140 and is constantly recorded in the internal memory 130 as video data 201 in the motion JPEG format. The video data 201 is a set of unit images 204 in JPEG format, and the unit images 204 are recorded in chronological order.

  The sound input to the microphone 192 is converted into digital data by the sound control unit 190 and recorded in the internal memory 130 as sound data 210. The audio data 210 is composed of digital data in linear PCM format.

  Here, when the acceleration sensor 170 detects an event such as an impact or when an event is detected by operating the recording button 180, the control unit 160 uses the video data 201 and audio data 210 recorded in the internal memory 130. The unit video data 202 and the unit audio data 211 recorded within a predetermined time before and after the event detection time (for example, 12 seconds before the event occurrence and 8 seconds after the event occurrence) are extracted. The extracted unit video data 202 and unit audio data 211 are recorded on the memory card 30 via the recording control unit 150.

  When the unit video data 202 is recorded on the memory card 30, the control unit 160 performs an encryption process on the unit video data 202. By performing the encryption processing of the unit video data 202, there is no possibility that the unit video data 202 recorded in the memory card 30 will be read or altered by a third party.

  Next, encryption processing in the embodiment of the present invention will be described.

  FIG. 4 is an explanatory diagram of the encryption processing of the unit video data 202 performed by the control unit 160 of the present embodiment.

  The control unit 160 acquires the unit video data 202 recorded within a predetermined time before and after the time when the event is detected from the internal memory 130. In this unit video data 202, unit images 204 in JPEG format are recorded continuously in time series.

  The unit image 204 includes a sequence header (SH) area 214 and a data area 215. In the SH area 214, information indicating that it is in the JEPG format, encoding information (Huffman table or quantization table) of data recorded in the data area, and the like are recorded. The SH area 214 generally has a capacity of several tens to several hundreds bytes. In the data area 215, binary data of an image encoded by the JPEG method is recorded.

  First, after acquiring the unit video data 202 from the internal memory 130, the control unit 160 acquires information indicating the position from the top of the unit image 204 from the acquired unit video data 202. Specifically, the control unit 160 acquires an address (or offset position) from each head for each unit image 204 included in the unit video data 202.

  The control unit 160 generates address information 205 that lists the acquired addresses of the unit images 204, and adds the address information 205 to the head portion of the unit video data 202.

  Next, the control unit 160 performs encryption processing of the unit video data 202 to which the address information 205 is added.

  In the encryption process, the control unit 160 encrypts the address information 205 and the area including the SH area 214 of each unit image 204 using the encryption key.

  The encryption key is created as a character string that is unique within the drive recorder 10 using, for example, a hash function. The encryption key has a numerical value of 0 to 255, for example. The control unit 160 performs encryption using a technique such as bit shift using the encryption key.

  Note that, for the region including the SH region 214 of each unit image 204, the control unit 160 sets the region including the SH region 214 and a part of the data region 215 as an encryption region 216.

  Information included in the SH region 214 includes information relating to JPEG encoding such as a Huffman code table and a quantization table as described above. This information is substantially the same if the size and compression rate of the unit image 204 are the same. Accordingly, the contents of the SH region 214 are substantially common data even in different unit images 204. Therefore, when only the SH area 214 is encrypted with the encryption key, the data after encryption tends to be a constant pattern even in different unit images 204. If the encrypted data has a certain pattern, the encrypted portion is easily discriminated by a third party, so that the unit video data 202 may be falsified.

  Therefore, in the present embodiment, not only the SH area 214 but also the area 216 including the SH area 214 and a partial area of the data area 215 is configured to be encrypted.

  Since binary data of an image encoded by the JPEG method is recorded in the data area 215, the contents of the area 216 including the partial area of the data area 215 in the SH area 214 are the same in different unit images 204. There is no content. Therefore, by encrypting this area 216, it is possible to prevent the encrypted data from having a different pattern in different unit images 204 and discriminating the encrypted part by a third party.

  Furthermore, in the unit video data 202 in which the unit images 204 are continuously recorded by performing the encryption including the SH area 214 of the unit image 204, the boundary between the unit image 204 and the unit image 204 is the third. Can not be determined from the person. Accordingly, it is extremely difficult for a third party to decode and acquire the individual unit images 204 from the unit video data 202, and the individual unit images 204 are prevented from being identified or altered by the third party. Is done. Further, since the area 216 to be encrypted is several hundred bytes, the processing load of the encryption process and the decryption process can be reduced.

  Note that a part of the data area 215 has a variable length based on the encryption key. For example, when the encryption key takes a value of 0 to 255, an area of 1 to 256 bits from the head part of the data area 215 can be included in the area 216 correspondingly.

  In addition to the SH area 214 and the partial area of the data area 215, the encryption area 216 is also a partial area of the end portion of the data area 215 of the unit image 204 recorded immediately before. (Several bytes) may be included. Information (EOF) indicating the end of the unit image 204 may be recorded at the end of the data area 215. Therefore, by encrypting the information indicating the end, it is possible to prevent the boundary portion between the unit image 204 and the unit image 204 from being identified by a third party.

  Further, when the unit video data 202 is reproduced on the PC 20, an encryption key common to the drive recorder 10 is generated by using the same hash function as that of the drive recorder 10, and the recorded unit video data 202 is stored in the unit 20. Decoding processing can be performed.

  By decrypting the encrypted address information 205 in the PC 20, the position and size of each unit image 204 included in the unit video data 202 can be easily determined. Then, the process of extracting one unit image 204 from the unit video data 202 is facilitated by decrypting the encrypted area 216 at the beginning of each unit image 204.

  FIG. 5 is a flowchart of the recording process of the unit video data 202 and the unit audio data 211 executed by the control unit 160 according to the embodiment of the present invention.

  As described above, the control unit 160 always records the video data 201 acquired by the camera 12 and encoded by the image processing unit 140 in the internal memory 130 (step S10).

  When the video data 201 is recorded in the internal memory 130, the control unit 160 determines whether an event is detected by the acceleration sensor 170 or the recording button 180 (step S11). If no event is detected, the process returns to step S10, and recording of the video data 201 and the audio data 210 is continued.

  If it is determined in step S11 that an event has been detected, the control unit 160 stores the unit video data 202 and the unit audio data 211 recorded from the internal memory 130 within a predetermined time before and after the time at which the event was detected. Extract (step S12).

  Next, the control unit 160 acquires an address from the head of each unit image 204 included in the extracted unit video data 202, and adds each acquired address to the head portion of the unit video data 202 as address information 205. (Step S13).

  Next, the control unit 160 encrypts the unit video data 202 to which the address information is added (Step S14).

  The control unit 160 encrypts the address information of the unit video data 202 using the encryption key determined as described above. Then, for each unit image 204 included in the unit video data 202, the area 216 including the SH area 214 and a part of the data area 215 is encrypted using the encryption key.

  Next, the control unit 160 outputs the encrypted unit video data 202 and unit audio data 211 to the recording control unit 150. The recording control unit 150 records the unit video data 202 and the unit audio data 211 on the memory card 30 (step S15).

  By such control, the drive recorder 10 can encrypt and record the unit video data 202 recorded within a predetermined time before and after the time when the event is detected.

  As described above, the drive recorder 10 according to the embodiment of the present invention is mounted on the vehicle 11, the camera 12 that acquires the video signal, and the video that is a set of the unit images 204 by encoding the video signal acquired by the camera 12. An image processing unit 140 that generates the data 201, a recording control unit 150 that controls recording of the video data 201 generated by the image processing unit 140, a control unit 160 that controls the image processing unit 140 and the recording control unit 150, The control unit 160 generates address information 205, which is recording position information indicating the recording position of the unit image 204 in the unit video data 202, when the recording control unit 150 records the video data 201 as the unit video data 202. The generated address information 205 is encrypted, and the SH area 2 included in the unit image 204 is Encrypt and region 216 that includes a portion of 4 and the data area 215, the unit image data 202 encrypted and configured to record on the memory card 30 via the recording control unit 150.

  With this configuration, in the encryption process performed by the control unit 160, only a partial area (the area 216 including the address information 205 and the SH area 214) of the unit video data 202 is encrypted. Processing is easier than encrypting the entire 202, and the processing load for encryption can be reduced.

  In addition, since the area 216 including the SH area 214 and the partial area of the data area 215 of the unit image 204 is encrypted, the encrypted data does not have a fixed pattern, and the encrypted data is transmitted to a third party. Is difficult to discriminate, so that it is possible to prevent falsification of the video data.

  Also, the address information 205, which is the recording position information indicating the recording position of the unit image 204, is recorded and encrypted. Therefore, when the unit video data 202 is reproduced, each of the encrypted unit video data 202 is recorded. Since the head position of the unit image 204 can be easily detected, the predetermined unit image 204 can be easily extracted from the unit video data 202.

  The SH area 214 of the unit image 204 is an area for recording a Huffman table and a quantization table indicating the encoding method of the unit image 204, and a part of the data area 215 is encrypted to a variable length. It becomes difficult for a third party to determine that the content of the unit video data 202 after conversion is a unit image 204 in the JPEG format, so that falsification of the image data can be prevented.

  Further, the drive recorder 10 includes an audio control unit 190 that acquires audio as audio data, and the control unit 160 transmits unit audio data 211 corresponding to the time when the unit video data 202 is recorded via the recording control unit 150. Thus, the drive recorder 10 can record the unit audio data 211 in addition to the unit video data 202.

  In addition, since the drive recorder 10 includes the acceleration sensor 170 or the recording button 180 as an event detection unit that detects an event, when the acceleration sensor 170 detects an impact or when a user operation is detected by the recording button 180, An event is detected, and unit video data 202 and unit audio data 211 recorded at a predetermined time before and after the event occurrence time can be recorded.

  Further, since the control unit 160 encrypts the boundary including the boundary portions of the plurality of unit images 204 included in the unit video data 202, it is difficult for a third party to determine the boundary of the unit images 204, and the encrypted portion is determined. Since it is difficult, alteration of video data can be prevented.

  In the embodiment of the present invention, the unit video data 202 and the unit audio data 211 are recorded on the memory card 30 as separate files. However, the present invention is not limited to this. As another embodiment, as shown in FIG. 6, unit audio 212 is generated by dividing unit audio data 211 by a predetermined unit, and unit video data 202 is data including unit image 204 and unit audio 211. be able to. For example, an amount of unit sound 212 corresponding to the time series of unit images 204 is recorded every several unit images 204.

  Even when the unit video data 202 is configured in this way, as described above, the control unit 160 generates address information of each unit image 204 and adds it to the head of the unit video data 202. At this time, the address of the unit sound 212 is also recorded in the address information 205. Then, the control unit 160 encrypts the address information 205 and the area 216 including the SH area 214 and a part of the data area 215. For the unit sound 212, the predetermined area 217 at the head portion is encrypted. This predetermined area 217 may be such that the boundary between the unit image 204 and the unit sound 212 is not discriminable by a third party, and is based on the encryption key, as with a part of the data area 215 described above. It may be variable length. Further, the predetermined area 217 may include a partial area at the end of the data area 215 of the unit image 204 recorded immediately before.

  In the embodiment of the present invention, the example in which the SH area 214 is recorded in each of the unit images 204 included in the unit video data 202 is shown, but the present invention is not limited to this. As yet another embodiment, as shown in FIG. 7, only one SH area 214 having a Huffman code table and a quantization table common to all unit images 204 is recorded at the head of the unit video data 202, and thereafter The unit video data 202 may be configured to continuously record the data area 215 as the unit image 204.

  Even when the unit video data 202 is configured in this way, as described above, the control unit 160 generates address information of each unit image 204 and adds it to the head of the unit video data 202. Then, the area 216 including the SH area 214 and a part of the data area 215 is encrypted for the unit image 204 at the head part. The unit image 204 recorded thereafter encrypts only a partial area 218 at the beginning of the data area 215. This partial area 218 may be of a size that the boundary part of the unit image 204 cannot be discriminated by a third party, and, like the partial area of the data area 215 described above, has a variable length based on the encryption key. Also good. Also, the partial area 218 may include a partial area at the end of the data area 215 of the unit image 204 recorded immediately before.

  It goes without saying that the present invention is not limited to the above-described embodiments, and includes various modifications and improvements that can be made within the scope of the technical idea.

1 Drive Recorder System 10 Drive Recorder 11 Vehicle 12 Camera 20 Personal Computer (PC)
30 Memory card 120 Flash ROM
130 Internal Memory 140 Image Processing Unit 150 Recording Control Unit 160 Control Unit

Claims (6)

A camera mounted on a vehicle and acquiring a video signal;
An image processing unit that generates video data that is a set of unit images from the video signal acquired by the camera;
A recording control unit that controls recording of the video data generated by the image processing unit;
A control unit that controls the image processing unit and the recording control unit,
The controller is
When recording the video data by the recording control unit,
Generating recording position information indicating a recording position of the unit image in the video data;
Encrypting the generated recording position information, and encrypting a header area and a part of the data area of the unit image,
A drive recorder, wherein the recording control unit records the video data including the encrypted recording position information and the unit image.   The drive according to claim 1, wherein the header area of the unit image is an area indicating an encoding method of the unit image, and the control unit encrypts the data area of the unit image to a variable length. Recorder. It has a voice control unit that acquires voice as voice data,
The drive recorder according to claim 1, wherein the control unit causes the recording control unit to record audio data corresponding to a time when the video data was recorded. It has an event detector that detects events,
The controller is
2. The video data recorded at a predetermined time before and after an event occurrence time is recorded by the recording control unit when the event detection unit detects an event occurring in the vehicle. 4. The drive recorder according to any one of items 1 to 3.   5. The drive recorder according to claim 1, wherein the control unit encrypts an area including boundary portions of the plurality of unit images included in the video data. The controller is
When recording the video data by the recording control unit,
The recording position information, the unit image, and the audio data are included in the video data,
6. The method according to claim 1, further comprising: encrypting a part of the audio data included in the video data and including a boundary part between the audio data and the unit image. Drive recorder described in 1.

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