JPH08307811A - Video signal recording device - Google Patents

Abstract

(57) [Summary] [Purpose] When a video signal is compressed and recorded on a hard disk, it is recorded so that it can be correctly decoded even if the recording is temporarily stopped due to vibration or the like. [Structure] An optical image formed on the surface of an image pickup device 3 through a lens 1 and an iris 2 is converted into an electric signal and processed by a camera signal processing circuit 7. In this process, the electric signal is converted into a digital signal. The compression circuit 5 compresses the image and temporarily stores it in the memory 7. Data is sequentially written from the memory to the hard disk 10 via the input / output management circuit 6 and the write control circuit 9. When the vibration detection circuit 11 detects vibration,
In order to avoid erroneous recording, the hard disk 10 suspends recording once. After the vibration has subsided, the data in the middle of writing is read again from the memory 7 and recorded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal recording apparatus for digitizing a video signal, compressing the video signal and recording the video signal. When the video recording is interrupted due to vibration or the like, it contributes to the improvement of the image quality of the reproduced image. The present invention relates to a recording device and its method.

[0002]

2. Description of the Related Art Conventionally, as a device for compressing and recording a still image, there is an electronic still camera, which records an image in a memory or a hard disk. As a commercially available product, for example, International Data Group
up) MacWorld magazine's September 1994 issue, Apple's Quic as using memory
The kTake 100 is described on pages 140-147, and the Kodak DSC420 digital camera using a hard disk is described on page 133.

It is well known that a hard disk is inferior in vibration resistance to a memory as compared with a memory, and a technique for preventing a recording failure due to vibration when a hard disk is used as a recording medium in an electronic camera is disclosed in Japanese Patent Application Laid-Open No. 5-130545. It is disclosed in the official gazette (hereinafter referred to as reference 1). In Reference 1, the camera is provided with a means for detecting vibration, and even if the user presses the shutter button to start photographing, writing to the hard disk is not performed while the vibration is detected, and the image is stored in the internal memory. Store. By starting writing to the hard disk after the vibration has subsided, recording failure on the hard disk is prevented.

Further, in the above-mentioned document 1, in FIG.
For the vibration generated while writing the image to the hard disk, after the writing is completed, the written content is compared with the original signal stored in the memory, and if they do not match, the writing is performed again. The algorithm is disclosed, and consideration is given to prevent recording failure even with vibration applied during writing on the hard disk.

[0005]

By the way, recently, as one of the methods for compressing and recording a moving image, MPE (MPE
G) has been proposed and its decoder is also commercially available. The encoder has become available as the semiconductor process advances. An application to a digital moving picture compression recording apparatus for compressing and recording a moving picture using this encoder can be considered.
In the case of MPEG1, the compressed video signal transfer rate is about 1.5M
It becomes bps data, and a recording capacity of 56MB is required for recording for 5 minutes. At present, hard disks or flash memory can cover this capacity. The flash memory is superior to the hard disk in earthquake resistance and shock resistance, but the price per unit capacity is very expensive. Therefore, it is not practical to use a flash memory for a consumer video signal recording device, especially a portable device, which needs to have a large capacity and be inexpensive.

[0006] The commercially available electronic camera of the above-mentioned known example can only record a still image, and cannot record a moving image. Furthermore, Document 1 discloses a technology assuming an electronic still camera, and cannot be applied to a moving image. On the other hand, even in the case of still images, the amount of data is large for the purpose of compressing and recording an ultra-high-definition image, and it takes time to record once. In the technique described in Reference 1, when vibration is applied during writing to the hard disk, the recorded contents are confirmed after one-way recording is completed. When recording an image such as an ultra-high-definition image that has a large amount of data and takes a long time to record once, the user has to wait a long time until the next recording.

One of the objects of the present invention is to solve the above problems and to provide a video signal apparatus for compressing and recording a moving image. Another object of the present invention is to provide a video signal recording apparatus which has improved usability, even when recording a still image having a large amount of data such as a high-definition image, the recording is completed quickly even when vibration is applied. is there.

[0008]

In order to achieve the above object, the present invention provides a video signal compression circuit, a memory for temporarily storing the compressed video signal, and a memory remaining for detecting a free space of the memory. An amount detection circuit, a recording circuit for recording the signal read from the memory, a vibration detection circuit for detecting the vibration applied to the recording circuit, and the recording circuit according to the detection result of the vibration detection circuit. A recording stop circuit for stopping recording to the memory, and a memory input / output control circuit for controlling writing / reading of the memory according to the results of the vibration detection circuit and the memory remaining amount detection circuit are provided.

[0009]

In a video signal device using a recording medium such as a hard disk which is vulnerable to shock and vibration in a recording circuit, when a large shock is applied to the device, the recording circuit prevents the recording error or protects the medium. The recording circuit temporarily interrupts recording. A compressed video signal is stored in a memory when a continuous image is recorded like a moving image. By using a hard disk with a transfer rate faster than the transfer rate of the compressed video signal, the amount of information stored in the memory will gradually decrease with time even if the compressed video signal is temporarily stored in the memory. To go.

Here, for example, an image compressed like MPEG is an intra-frame coded image (hereinafter referred to as I picture), an inter-frame forward predictive coded image (hereinafter referred to as P picture), and a bidirectional predictive coded image. When it is composed of (hereinafter referred to as B picture), if the recording is interrupted and the data is lost, the decoding cannot be performed correctly. Regarding the image processing of the MPEG method, for example, ISO / IE which is an international standard.
C 11172-1, 11172-2, 11172-3: 1993 and Hiroshi Fujiwara's "Latest MPEG Textbook" (Ascii Publishing, 1994).

Generally, in a hard disk, information is divided and recorded in units called sectors. In the video signal recording apparatus of the present invention, when a large shock or vibration is applied to the recording circuit during recording, the write head of the hard disk shifts,
Recording is interrupted in order to prevent recording outside the original track and rewriting data on other tracks. When the vibration is below the allowable limit, the recording circuit re-records the sector that was being written from the beginning. Therefore, in the input / output control circuit of the memory of the present invention, the recording information required by the recording circuit is sent again. In this way, at least the video compressed on the hard disk as the recording circuit is continuously recorded, and the recording for each frame is completed.

In order to reduce the cost of parts, the upper limit cannot be set for the expensive memory capacity. If vibration or impact continues for a long time, the memory capacity may not be accommodated. In that case, in order to prevent over-flow of the memory, writing to the memory is interrupted or information in the memory is erased and overwritten. In MPEG image compression, a B picture is an image predicted bidirectionally on the time axis, and even if the B picture is lost, it does not affect the decoding of other frames. Therefore, the remaining memory capacity detection circuit detects the remaining capacity of the memory and deletes one or several B pictures in the memory to secure the memory capacity.

Another effect of the present invention is that if the recording interruption period becomes long, the memory capacity may become insufficient by simply deleting a few B pictures. In that case, MPEG
The data in the memory is overwritten or erased in units of group of pictures (hereinafter called GOP). GOP
Is a set of data composed of I, P, and B pictures, and is often composed of ten or more frames.
By deleting or overwriting the data in the memory in units of GOPs, the compressed image recorded in the recording circuit is reproduced correctly as data, although the deleted GOPs cause discontinuity in the video. Here, since the GOPs are not completely independent, when playing back the first few B pictures of the first GOP that resumed recording, the playback screen may be momentarily disturbed because the frame that is referenced for decoding is incorrect. There is. However, assuming that there are two B pictures, it takes only 0.07 seconds,
It is fully acceptable.

Another effect of the present invention is also effective when recording an ultra-high definition image having a large amount of data. Even if the recording is interrupted due to vibration or the like, since the sector being written to the hard disk is re-recorded again, it is possible to record without missing data.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of an embodiment of a video recording apparatus according to the present invention, in which 1 is a lens, 2 is an iris, 3 is an image sensor, 4 is a camera signal processing circuit, 5 is an image compression circuit, and 6 is an image compression circuit.
Is a memory input / output management circuit, 7 is a memory, 8 is a memory free space detection circuit, 9 is a hard disk write control circuit, 10 is a hard disk, 11 is a vibration detection circuit, 12
Is a system control circuit of the video signal device.

In FIG. 1, the optical image input through the lens 1 is adjusted in light amount by the iris 2 and formed on the image pickup element surface to be converted into an electric signal. Camera signal processing circuit 4
Is a circuit known in video cameras, such as an automatic gain adjustment circuit, a matrix circuit, and a gamma processing circuit. Further, an analog / digital conversion circuit is arranged in the middle of the signal path of the circuit configuration and outputs a digitized video signal.

The compression circuit 5 compresses the image signal by a preset method. A case of compressing a moving image with MPEG will be described with reference to FIG. FIG. 2 (1) shows an original image input to the compression circuit for each frame, and the numbers in the figure are temporary frame numbers. In MPEG, compression is performed by three types of encoding: an intra-frame coded image (I picture), an inter-frame forward predictive coded image (P picture), and a bidirectional predictive coded image (B picture).

An I picture is an image whose coding is completed in the frame, a P picture is an image coded by predicting in the positive direction of the time axis based on the I or P picture, and a B picture is I or It is an image coded by predicting from the positive and negative directions along the time axis based on the P picture. Figure 2 (2)
Figure 1 (1) with a GOP cycle of 15 and an I or P interval of 3
The image obtained by encoding the original image of is shown for each frame. I, P, and B in the figure respectively represent an I picture, a P picture, and a B picture, and the numbers correspond to the frame numbers of the original image.

The image compressed as described above is temporarily stored in the memory 7 via the memory input / output management circuit 6. The image stored in the memory 7 is written in the writing control circuit 9
The data is read from the memory 7 and written in the hard disk 10 according to the request from the. The write control circuit 9 divides the data from the memory 7 into sectors, which are recording units of the hard disk 10, and transfers the data to the hard disk 10. By using the hard disk 10 whose writing speed is sufficiently higher than the data transfer speed from the compression circuit 5, the memory 7 does not overflow.

The above is the signal flow in the normal state. Next, the operation when vibration or shock is applied to the video signal recording apparatus of the present invention will be described with reference to FIGS.

FIG. 3A shows the vibration detection circuit 11 shown in FIG.
Is the waveform of the vibration detected. FIG. 2 (b) shows the position of the write head of the hard disk 10 (not shown in FIG. 1) on the disk by sector number, and FIG. 2 (c) shows the operating state of the hard disk 10. . Until the vibration starts, the hard disk 10 is in a recording state as shown in FIG. 3 (c), and the writing sector advances from n-2 to n-1. It is assumed that vibration is detected at time T1 during writing of the nth sector.

The hard disk write control circuit 9 immediately interrupts recording on the hard disk 10 in order to prevent erroneous recording, but the disk continues to rotate. Recording is suspended while vibration continues. When the vibration falls below the allowable limit at time T2, the write control circuit 9 is in a ready state for starting recording. In order to re-record the n-th sector which was being recorded, the write head of the hard disk starts writing from the memory 7 at time T3 when it reaches the head of the n-th sector.
The image data to be recorded in n is stored in the memory 7
Read from and record. Keep recording like this,
The image signal stored in the memory 7 is recorded in the recording device 7 without interruption.

As described above, according to this embodiment, even if the recording is temporarily interrupted, the recording can be restarted based on the signal stored in the memory, so that the information to be recorded is not lost. Therefore, the image can be decoded as if the recording was not interrupted at the time of reproduction. Further, when the recording is interrupted, the re-recording is performed in the minimum recording unit of the recording circuit, so that the time required for the re-recording can be minimized. Therefore, even when a high-definition still image is recorded, not all images are rewritten when recording is restarted from the temporary interruption of recording due to vibration that occurred during shooting, so the recording time can be shortened. Therefore, there is an effect that the time until the next shooting can be shortened and the interval between continuous shootings can be shortened.

In the embodiment of the present invention shown in FIG. 1, the lens 1, the image pickup device 3, and the camera signal processing circuit 4 are shown.
The signal processing shown in the present embodiment is naturally applied to an apparatus which does not have such an image pickup system but has an external video input terminal and supplies a video signal directly to the compression circuit from the outside. Further, in addition to the configuration shown in FIG. 1, a video signal is provided such that such an external input terminal and a switch circuit are provided in front of the compression circuit 5 so that a camera shoots a subject and a video signal is externally supplied. A processing device can also be realized as an application of the present invention.

Further, in the embodiment shown in FIG. 1, the memory 7 is illustrated concretely for ease of explanation, but since the normal compression circuit 5 uses the memory in the process of encoding, that memory is used. It can be used as a substitute for the memory 7 of FIG. In that case, the memory input / output circuit 6 and the memory 7 are included in the compression circuit in a broad sense.

Another embodiment according to the present invention will be described with reference to the timing chart of FIG. The difference from the operation of the first embodiment shown in FIG. 3 is that the compressed image stored in the memory 7 is skipped frame by frame and transferred to the hard disk 10. It is not a good idea to use a lot of expensive memory 7 in terms of cost.
It is desirable to minimize the capacity of. By reducing the capacity of the memory 7, if the recording of the hard disk 7 is stopped for a long time, a problem of overflow of the memory 7 occurs. An embodiment for preventing the overflow will be described below with reference to the timing charts of FIGS. 1 and 4.

FIG. 4A is a waveform of the vibration detected by the vibration detection circuit 11, and FIG. 4B is a compressed image written in the memory circuit 7 in units of frames, where I, P and B are respectively. , I picture, P picture, B picture, and each number indicates a frame number. Until time T1, the image signal written in the memory 7 is written in the hard disk 10 as it is. It is assumed that vibration occurs at time T1 when the B picture 6 is being written, and the vibration falls below the allowable limit at time T2. The point that writing to the hard disk is immediately interrupted at time T1 is the same as in the example of FIG.

While the hard disk 10 suspends writing, the compression circuit 5 continues to compress the image and writing to the memory 7 continues. At time T2, it is assumed that the B picture 7 is written in the memory 7. In order to complete the writing of the B picture 6 whose recording was interrupted during the writing, the writing control circuit 9 searches the hard disk 10 for the beginning of the B picture 6, and at time T2, starts recording the B picture 6 again from the beginning. .
Then, in order to reduce the time difference between the data in the memory 7 and the data being written to the hard disk 10, the next B picture 7 is skipped and the P picture 8 is written to the hard disk next to the B picture 6. The memory I / O circuit 6 performs the operation of jumping over the B picture 7.

The frames to be skipped here are
That is, it must be a B picture for the convenience of referring to data at the time of decoding. Since I picture and P picture are referenced for decoding of other frames during playback, they cannot be omitted. According to this embodiment, even if the recording of the compressed image on the hard disk is interrupted due to vibration with a small memory, the recording can be continued without overflowing the memory.
Furthermore, since the recorded compressed image is recorded without missing the frame that is referred to during decoding, in the reproduced image,
Image distortion such as block distortion caused by referring to an inappropriate image does not occur.

In this embodiment, an example in which a frame is skipped when reading data from the memory 7 has been described. However, in the memory 7, another frame data is overwritten on the B picture 7 and the frame is equivalently written. The same effect can be obtained by skipping. Although the case where the B picture 6 is rewritten from the beginning has been described, the B picture 6 may be rerecorded from the sector being written as described in the timing chart of FIG. In that case, there is an effect that the time difference between the image written in the hard disk 10 and the image written in the memory 7 becomes small.

FIG. 5 is a timing chart showing still another embodiment according to the present invention, and the block configuration is the same as that shown in FIG. The difference from the embodiment of FIGS. 3 and 4 is that
The period of vibration or shock is longer, and thus the period during which recording is suspended is longer. Figure 5
(A) shows the waveform of the vibration detected by the vibration detection circuit 11, and (b) shows the compressed video signal stored in the memory 7 of FIG. 1 in units of GOP. Indicates the order. Here, one GOP is the same as that shown in FIG.
It shall consist of a frame image. 15 frames are about 0.5 seconds in time, and an application example of the present invention in the case where a signal or a shock extends for several seconds will be described.

Normal recording is performed until time T1. The image in the memory 7 shown in FIG. 5B is recorded as it is on the hard disk 10 shown in FIG. Vibration starts at time T1, and the hard disk 10 immediately stops recording. At this time, as shown in FIG. 5D, it is assumed that the hard disk 10 is recording the eighth frame in GOP3. Until the time T2, the hard disk 10 stops recording, and from the time T2 when the vibration subsides, the information of the frame 8 in the GOP3 stored in the memory 7 is stored in the memory 7 by the same method as in the embodiment shown in FIG. Further, the hard disk 10 re-records the sector of the frame which has already been recorded halfway from the beginning.

On the other hand, in the memory 7, at time T2
Writing GOP5. The remaining memory amount detection circuit 8 detects the remaining amount of memory, and when it judges that there is not enough memory capacity, skips GOP3 and then GOP4 and GOP5, for example.
Read P6. Therefore, other information can be recorded in the capacity of two skipped GOPs. Here, the remaining memory amount detection circuit 8 can be realized, for example, by using a so-called FIFO type memory as the memory 7 and utilizing its write pointer and read pointer. After the time T2, the writing speed of the hard disk 10 is faster than the transfer rate of image compression, so that the time difference between the image written in the hard disk 10 and the image written in the memory 7 becomes gradually smaller. Considering only the continuity of the reproduction screen, it is desirable that the memory 7 has a large capacity, but the capacity is set in consideration of the component cost and is not limited. Similar to the technique shown in this embodiment, the device designer can arbitrarily set the memory capacity in consideration of the cost of parts and the reproduced image quality.

According to the present embodiment, recording of one GOP is completed without overflowing the memory even when vibration or shock is long for several seconds, so that decoding at the time of reproduction is normally performed. It is possible to suppress screen distortion such as block distortion. Furthermore, there is an effect of reducing the required amount of expensive memory to the minimum, and an effect of reducing the cost of the device. In the present embodiment, an example in which information in the memory is skipped or overwritten in GOP units has been described. However, when vibration continues for a long time, when writing to the memory, the data is updated when a certain GOP is written. It is also possible to prevent the memory overflow by temporarily suspending the writing.

An example in which a hard disk is used as a recording circuit in the block configuration shown in FIG. 1 is shown in FIG.
Although the description has been given with reference to the timing charts of FIGS. 4 and 5, the present invention can be applied to an apparatus using a flash memory as a recording circuit, although there is a difference in permissible limit against vibration and shock. Further, in the present embodiment, a circuit for detecting a signal applied to the recording circuit and a shock is provided, but the output of the acceleration sensor for camera shake compensation used in the recent portable camera-integrated video recording device is used. It is also possible to adopt a configuration in which vibration or impact is detected by using the Further, in FIG. 1, the hard disk 10 may have a detachable structure as defined by the PCMCIA standard, for example.

[0036]

As described above, according to the present invention,
A memory that temporarily stores compressed images and a circuit that controls the input and output of the memory are provided.When vibration is detected, recording of image signals is stopped from the memory in a recording circuit that is not strong against vibration, such as a hard disk. By re-recording the signal in the middle of writing to the recording circuit after the error is set, it is possible to record the recorded image without omission. Therefore, decoding of the compressed image is not a problem. Further, by restarting the recording from the part in the middle of recording, the time required for re-recording can be shortened, and particularly when recording a still image, the time until the next shooting can be shortened, and the usability is improved.

Further, when the vibration is prolonged and the memory capacity is insufficient, a frame is selected and the reading from the memory is skipped, erased or overwritten on a frame-by-frame basis to decode the discontinuity of the recorded image. Sometimes it can be okay. By using the interlaced reading of images from the memory, partial erasing, or partial overwriting, it is possible to minimize the use of expensive memory and also reduce the cost.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a video signal recording device according to the present invention.

FIG. 2 is a timing diagram illustrating a method of moving picture compression.

FIG. 3 is a timing diagram showing the operation of an embodiment of a video signal device according to the present invention.

FIG. 4 is a timing diagram showing the operation of another embodiment of the video signal device according to the present invention.

FIG. 5 is a timing diagram showing the operation of another embodiment of the video signal device according to the present invention.

[Explanation of symbols]

 5 Image compression circuit 6 Input / output management circuit for memory 7 Memory 8 Memory free space detection circuit 9 Hard disk write control circuit 10 Hard disk 11 Vibration detection circuit

Claims (6)

[Claims] 1. A video signal recording apparatus for compressing and recording a video signal, a compression circuit for compressing the video signal, a memory for temporarily storing the compressed video signal, and a free space of the memory detected. Memory remaining amount detecting circuit, a recording circuit for recording the signal read from the memory, a vibration detecting circuit for detecting the vibration of the recording circuit, and the recording circuit according to the detection result of the vibration detecting circuit. A recording stop circuit for stopping recording on the memory, and a memory input / output control circuit for controlling writing / reading of the memory according to the results of the vibration detection circuit and the memory remaining amount detection circuit. A video signal recording device characterized by. 2. A video signal recording device for compressing and recording a video signal, a compression circuit for compressing the video signal, a memory for temporarily storing the compressed video signal, and an available capacity of the memory is detected. Memory remaining amount detecting circuit, a recording circuit for recording the signal read from the memory, a vibration detecting circuit for detecting the vibration of the recording circuit, and the recording circuit according to the detection result of the vibration detecting circuit. A recording stop circuit that stops recording on the memory, and a memory input / output control circuit that controls writing / reading of the memory according to the results of the vibration detection circuit and the memory remaining amount detection circuit. And an image sensor for photoelectrically converting an optical image formed by the lens to generate an electrical video signal, and a camera signal processing circuit for processing the video signal. Image signal recording apparatus. 3. The input / output control circuit of the memory is configured such that after the recording stop is released by the recording stop circuit, a frame which is being written by the recording circuit is completed without omission.
The video signal recording apparatus according to claim 1 or 2, wherein writing to the recording circuit is restarted. 4. The memory can be partially erased or overwritten, and the input / output circuit of the memory changes the contents of the memory into a frame of a video signal according to the output of the memory remaining amount detection circuit. Erase or overwrite in units,
4. The video signal recording device according to claim 1, wherein writing to the memory is performed. 5. The image compression is performed by combining one or more of intra-frame coding, inter-frame forward predictive coding and bidirectional predictive coding, and the erasing or overwriting of the memory contents is performed by the code. 5. The video signal recording device according to claim 1, wherein the video signal recording device is performed in units of a combination. 6. The input / output control circuit of the memory deletes information stored in the memory after the encoding combination unit which was being written in the recording circuit in units of the combination or later deletes the information. 6. The video signal recording apparatus according to claim 1, wherein writing of the memory is controlled so as to be rewritten with information to be recorded, and the compression of the image is restarted from the intraframe compression.