JP3880892B2 - Video recording / playback device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a moving image recording / reproducing apparatus, and more particularly, to a moving image recording / reproducing apparatus that displays a warning when it is determined that an image recorded during recording of a moving image cannot be correctly reproduced.
[0002]
[Prior art]
In general, with the international standardization of image encoding methods, the improvement of moving image encoding technology has become active. One of the international standards is the MPEG (Moving Picture Expert Group).
[0003]
In this MPEG method, motion compensation is performed to reduce redundancy in the time axis direction, image differences are taken, and then DCT (discrete cosine transform), which is a type of orthogonal transform, is used to reduce redundancy in the spatial axis direction. ) And variable length coding schemes. Further, for the reduction of redundancy in the time axis direction, a property that a continuous moving image has high correlation between frames before and after or between fields is used.
[0004]
That is, a motion vector is detected for each block between an image to be encoded (current image) and an image that is temporally before and after, and after predicting the current image by performing motion prediction, between the two The prediction error at is calculated. Here, each image constituting the moving image has three types of I picture (frame or intra-field encoded image), P picture (forward prediction image), and B picture (forward, backward, bidirectional prediction image). And then encoded. On the other hand, for redundancy in the spatial axis direction, the prediction error signal of each image is quantized with respect to the DCT coefficient in units of blocks, and then variable length coding is performed.
[0005]
Japanese Patent Application Laid-Open No. 11-298890 discloses means that does not cause deterioration in image quality even for an image with a large change in motion by changing the frame rate in accordance with the magnitude of the change in motion. Has been.
[0006]
[Problems to be solved by the invention]
However, with the above method, when recording an image with a large change in motion, the motion vector for each block between the current image and the temporally preceding and following images becomes too large, and encoding is performed at a low bit rate. If recorded in this way, information loss will increase, resulting in a mosaic-like image that is totally blurred when played back, and the recorded image may not be played back correctly.
[0007]
In the technique described in Japanese Patent Application Laid-Open No. 11-298890, an image with a large change in motion in which the amount of data per frame increases is controlled to increase the frame rate. There is a problem that the bit rate is temporarily too high, and reading / writing to the recording medium cannot be performed in real time.
[0008]
The present invention has been made in view of the problems of the prior art as described above, and the object of the present invention is that a recorded moving image cannot be correctly reproduced while an image with a large change in motion is being recorded. It is to provide a moving image recording / reproducing apparatus that allows a user to recognize the above.
[0009]
[Means for Solving the Problems]
In order to achieve the above-described object, the moving image recording / playback apparatus according to the present invention includes a motion change amount determination unit that determines a change amount of motion, and information loss increases during recording of an image having a large change in motion. When it is determined that the recorded image cannot be correctly reproduced, a warning is displayed on the display unit informing that the recorded moving image cannot be correctly reproduced. In addition, a recording method selection unit is provided for selecting whether to record at a reduced frame rate when it is determined that reproduction is not possible.
[0010]
Furthermore, an NG flag is recorded in a frame that is determined to be unable to be reproduced correctly.
[0011]
Further, the user can arbitrarily set a default setting storage unit for setting a default value (initial setting value) as a motion change amount threshold value used in the motion change amount determination unit, and a motion change amount threshold value used in the motion change amount determination unit. And a switching means for switching whether to use the data in the default setting storage unit or the data in the change amount setting unit as the threshold value of the change amount of motion.
[0012]
Furthermore, when an NG flag is detected during playback of a moving image, a warning is displayed on the display unit informing that the moving image cannot be correctly played back, as in recording.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0014]
FIG. 1 is a block diagram showing a configuration of a moving image recording / playback apparatus according to an embodiment of the present invention. As shown in FIG. 1, the moving image recording / reproducing apparatus of the present embodiment includes an image input unit 101 including a CCD and an AGC circuit, a signal processing unit 102 that generates Y, U, and V signals, and a control that controls the entire system. Unit 103, DMA (Direct Memory Access) controller 104, memory 105, image compression / decompression unit 106, recording / reading unit 107 for recording and reading compressed data on a medium (recording medium), recording medium 108, display unit interface 109, display (Display unit) 110, a movement change amount determination unit 111, a change amount setting unit 112, a default setting storage unit 113, a changeover switch 114, and a recording method selection unit 115 are provided.
[0015]
First, the operation before photographing will be described based on the flowchart of FIG. Whether the user sets a threshold value for the amount of change in motion for performing a warning display notifying that reproduction cannot be correctly performed using the changeover switch 114 in advance or whether to use a default value (an initial setting value prepared in advance by the apparatus itself). Select (step S11). When set by the user, a threshold value of the movement change amount is set via the change amount setting unit 112. When a default value (initial setting value) is used, the value in the default setting storage unit 113 is used as a threshold value for the movement change amount. Further, when it is determined that the image cannot be correctly reproduced through the recording method selection unit 115, the frame rate is reduced (hereinafter referred to as image quality priority mode), or a mosaic image is not reduced. Whether to record (hereinafter referred to as frame rate priority mode) is selected (step S11). When the image quality priority mode is selected in step S11, if the motion change is large and the motion change amount exceeds the threshold value, a mode for recording at a reduced frame rate (image quality priority mode) is set. When the frame rate priority mode is selected in S11, a mode for recording without reducing the frame rate (frame rate priority mode) is selected even when the change in motion is large and the amount of change in motion exceeds the threshold. In both the image quality priority mode and the frame rate priority mode, if the amount of change in motion exceeds a threshold value, a warning message indicating that playback cannot be performed correctly is displayed and an NG flag is recorded. The
[0016]
Next, an actual photographing operation will be described. First, an optical signal of a photographed subject is input to the image input unit 101, photoelectrically converted into an analog video signal, subjected to processing such as AGC, and output to the signal processing unit 102. The video signal input to the signal processing unit 102 is A / D converted and converted into a digital signal, and is subjected to processing such as gamma correction, filtering, and contour enhancement processing, and Y (luminance), U (red color difference) ), V (blue color difference) signal is generated. And the control part 103 memorize | stores the Y, U, V signal produced | generated based on the program in the memory 105. FIG.
[0017]
Next, the stored digital video signal is read out to the image compression / decompression unit 106 via the DMA controller 104 and subjected to compression processing. The compressed data is temporarily stored in the memory 105, then header information is attached according to a predetermined format by the control unit 103, and then recorded on the recording medium 108 via the recording / reading unit 107.
[0018]
In the case of long-time moving image recording, compression is performed in several times and is recorded as one file when recording on a recording medium. Therefore, the header in which the photographing start time is recorded is attached only by the first compression when recording is started.
[0019]
Here, the determination of the movement change amount will be described. Usually, a motion vector is obtained for each macroblock of a 16 × 16 image. An image of QVGA (Quarter Video Graphics Array; horizontal 320 × vertical 240 pixels) is composed of 300 macroblocks. For example, when the motion change amount threshold is set to 10 or 200 macroblocks with a motion vector size (half pixel unit), or when there are 200 or more macroblocks with a motion vector size of 10 or more In addition, it is determined that the amount of change in motion is large. That is, when the above condition is satisfied, a warning is displayed on the display 110, and at the same time, an NG flag is recorded in the corresponding frame.
[0020]
Next, the operation when the change amount of the movement becomes large will be described based on the flowchart of FIG. The operation up to the compression processing is the same as the conventional one. The stored digital video signal is read out to the image compression / decompression unit 106 via the DMA controller 104 and subjected to compression processing. At this time, it is determined whether or not the currently processed image is an I picture (step S21). If it is an I picture, the process proceeds to step S30. If not, the process proceeds to step S22.
[0021]
In step S22, the motion change amount A and the motion change amount threshold B of the previous image and the currently processed image are sent to the motion change amount determination unit 111, and the process proceeds to step S23. In step S23, it is determined whether or not the motion change amount A exceeds the threshold B. If A> B, the process proceeds to step S24, and if A> B, the process proceeds to step S29. In step S24, a warning signal is sent from the motion change amount determination unit 111 to the control unit 103 indicating that the motion change amount A exceeds the threshold, and the process proceeds to step S25. In step S25, the control unit 103 that has recognized the warning signal displays a warning message such as “The recorded image cannot be reproduced correctly because the movement is too intense” on the display 110 via the display unit interface 109, and in step S26. move on. In step S26, it is determined whether the image quality priority mode is set or the frame rate priority mode is set. If the frame rate priority mode is set, the process proceeds to step S27, where the image quality priority mode is set. If is set, the process proceeds to step S28.
[0022]
In step S27, an NG flag is set in the user data portion of the picture layer of the currently processed image, and the process proceeds to step S29. In step S29, the currently compressed image (P or B picture image) is temporarily stored in the memory 105 and then stored in the recording medium.
[0023]
In step S28, the currently processed image (P or B picture image) is not recorded, and the process proceeds to the next image.
[0024]
If the warning is being displayed in step S30, the process proceeds to step S30 when the picture is an I picture, the NG flag is set, the currently compressed I picture image is recorded on the recording medium 108, and the warning is displayed. If not, the currently compressed I picture image is recorded on the recording medium 108 as it is.
[0025]
As described above, in this embodiment, when the image quality priority mode is set, by recording only I pictures, the amount of information per frame is increased and the frame rate is reduced, but the image quality is reduced. Record beautiful images. At this time, a warning is displayed and an NG flag is set when recording an I picture. On the other hand, when the frame rate priority mode is set, by recording all compressed frame data, the frame rate is constant, but a mosaic image is recorded. At this time, a warning is displayed and the NG flag is set when all the pictures are recorded. If A> B, the normal recording operation is continued.
[0026]
Next, the reproduction operation will be described. One moving image file recorded on the recording medium 108 is read by the recording / reading unit 107 and stored in the memory 105 via the DMA controller 104. Next, the header information is read from the memory 105 to the control unit 103, and the recorded shooting start time is read. Further, the image data written in the memory 105 is sent from the memory 105 to the image compression / decompression unit 106 via the DMA controller 104, decompressed, and stored in the memory 105 again. Next, the decompressed data from the memory 105 is sent to the display 110 via the DMA controller 104 and the display interface 109 and displayed.
[0027]
Next, the operation during reproduction when the NG flag is detected will be described with reference to the flowchart of FIG. The operation until the decompression process is the same as the conventional one. The image data written in the memory 105 is sent from the memory 105 to the image compression / decompression unit 106 via the DMA controller 104, decompressed, and stored in the memory 105 again (step S41). At this time, the control unit 103 monitors whether or not the NG flag is recorded in the user data portion of the picture layer of the currently processed image (step S42). A warning is displayed on the display 110 in the same manner as during recording (step S43). Also in this case, the image reproduction operation is continuously performed.
[0028]
In the above-described embodiment, it is necessary to always set a threshold value of a motion change amount for performing a warning display notifying that reproduction cannot be performed correctly at the time of reproduction, so that either the image quality priority mode or the frame rate priority mode is set. However, no threshold is set for determining the amount of change in motion, no warning is displayed no matter how intense the image is recorded, and no NG flag is recorded. A similar recording mode may be added to the image quality priority mode and the frame rate priority mode.
[0029]
【The invention's effect】
As described above, according to the present invention, when it is determined that a recorded image cannot be reproduced correctly, a warning is displayed to notify that the recorded image cannot be reproduced correctly. It is possible to realize a moving image recording / reproducing apparatus that never knows that there was no video.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a moving image recording / playback apparatus according to an embodiment of the present invention.
FIG. 2 is a flowchart showing a processing flow before shooting in the moving image recording / playback apparatus according to an embodiment of the present invention;
FIG. 3 is a flowchart showing a processing flow when the amount of change in motion increases in the moving image recording / playback apparatus according to the embodiment of the present invention.
FIG. 4 is a flowchart showing a processing flow when an NG flag is detected during playback in the moving image recording / playback apparatus according to the embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 101 Image input part 102 Signal processing part 103 Control part 104 DMA controller 105 Memory 106 Image compression / expansion part 107 Recording / reading part 108 Recording medium 109 Display part interface 110 Display 111 Motion change amount determination part 112 Change amount setting part 113 Default setting memory | storage part 114 Changeover switch 115 Recording method selection section

Claims (3)

A motion change amount determination unit that determines a change amount of motion , and a recording method selection unit that selects whether to record at a reduced frame rate when it is determined that the recorded image cannot be correctly reproduced ,
A large image of the motion changes during recording, loss of information is increased, to display when it is determined that the recorded image can not be correctly reproduced on the display section a warning indicating that moving image recorded can not be played correctly Turkey A moving image recording / reproducing apparatus characterized by the above. The moving image recording / reproducing apparatus according to claim 1,
A default setting storage unit for setting a default value as a threshold value of the motion change amount used in the motion change amount determination unit, and a change amount for the user to arbitrarily set a threshold value of the motion change amount used in the motion change amount determination unit A moving image recording / reproducing apparatus comprising: a setting unit; and a switching unit that switches between using data of a default setting storage unit or using data of a change amount setting unit as a threshold value of a change amount of motion. The moving image recording / reproducing apparatus according to claim 1,
An NG flag is recorded in a frame that is determined to be unable to be correctly played back, and if a NG flag is detected during playback of a moving image, a warning is displayed on the display unit informing that the moving image cannot be played back correctly, as in recording. A moving image recording / reproducing apparatus characterized by the above.

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