JPH07282549A - Device for recording/reproducing compression image data - Google Patents

Abstract

PURPOSE:To prevent the disturbance in a reproducing image. CONSTITUTION:In an encoder 1, the image data are compressed by a encoding part 11, and the obtained compression image data are punctuated making a prescribed length bit line one unit by an error detection data addition part 12, and the error detecting data are added at every unit. The compression image data are recorded on a recording medium 3 by a data streamer 2. In a decoder 4, the compression image data read out from the recording medium 3 by the data streamer 2 are stored in a buffer memory 41 temporarily. Then, whether or not the error occurs is detected by an error detection part 42 at every unit, and when the error occurs, when a code showing the top of the image data is detected by a frame sync. detection part 43, a controller 44 interrupts a decoding process by a decoding part 45, and holds the present display data of a frame memory 46.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compressed image data recording / reproducing apparatus for recording and reproducing compressed image data.

[0002]

2. Description of the Related Art FIG. 3 shows the configuration of a conventional compressed image data recording / reproducing system. In the compressed image data recording / reproducing system shown in FIG. 3, error detection data is not added to the compressed image data bit stream itself encoded by the encoder 31, and the data streamer ( (Data recording / reproducing apparatus) 32 unique error correction code was added. Recording medium 3 during playback
The data read from No. 3 is subjected to error correction processing unique to the data streamer 32, and then passed to the buffer memory 341 of the decoder 34.

When the frame sync detector 342 detects the code indicating the beginning of each frame, the controller 343.
A detection signal is output to. Frame sync detector 3
The head of the frame at 42 does not correspond to the so-called head of each image, but represents the head of a unit completed as compressed data. That is, if the compression is completed for each so-called image, the beginning of each image is detected, and if it is completed for 1/2 of the image, the beginning of 1/2 screen is detected. To do. In addition, when it is completed with several screens, for example, when interframe predictive coding is used, the head of several screens is detected. The decoding unit 344 decodes the image compressed data bitstream and stores it in the frame memory 345.

[0004]

As described above, the error correction process when reading data is performed by the data streamer 3
2 and the decoder 34 uses the data streamer 32.
Unless the information indicating that an error has occurred is received, the received compressed image data bit stream is judged to be correct and decoding processing is performed. Therefore, if the data streamer 32 does not have an error correction processing function, or if the data streamer 32 does not have a function of passing error occurrence information to the decoder even if an error occurs, or a function such as interpolation processing unique to the recording system. If the data is changed due to the above, the conventional bit stream is destroyed, and as a result of the decoding process being performed by the decoder 34 as it is, the decoding process fails, the reproduced image is disturbed, or An image that is far from the replay image of was sometimes displayed.

As a data streamer, for example, D2-VTR
For error correction processing unique to the data streamer when using the DST, refer to, for example, "D-2 Composite Digital VTR Television Society Journal vol.42, No.5 (1988)", "VTR Standard
(II) D-2 Format Television Society Journal vol.45,
No. 3 (1991) ”, so detailed description will be omitted.

An object of the present invention is to provide a compressed image data recording / reproducing apparatus capable of solving the above problems and preventing collapse of a reproduced image.

[0007]

In order to achieve such an object, the present invention provides a recording means for compressing image data and recording a compressed image data bit stream obtained on the recording medium; In a compressed image data recording / reproducing apparatus having a reproducing means for reproducing the compressed image data recorded on a recording medium, the recording means divides the compressed image data bit stream by dividing a bit string having a predetermined length as one unit. Means and error detecting data adding means for adding error detecting data to each unit divided by the dividing means, and the reproducing means determines whether or not an error has occurred in the read compressed image data. Error detection means for detecting whether or not each unit, and an interruption procedure for stopping the decoding process when an error is detected by the error detection means. If, when the decoding process is stopped by the stop means, characterized in that a holding means for holding the decoded image of the decoding process immediately before.

[0008]

In the recording means, the compressed image data bit stream is divided by the dividing means with a bit string of a predetermined length as one unit, and the error detecting data adding means adds the error detecting data to each divided unit. In the reproducing means, whether or not an error has occurred in the read compressed image data is detected by the error detecting means for each unit, and if an error is detected, the decoding processing is stopped by the stopping means and the decoding is performed. When the encoding process is stopped, the retaining unit retains the decrypted image immediately before the decryption process.

[0009]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes an encoder, which is composed of an encoder 11 and an error detection data adder 12. The encoding unit 11 performs an encoding process (compression) of the input image data. The error detection data addition unit 12 divides the compressed image data bit stream obtained by compression by the encoding unit 11 into units of a bit string having a predetermined length, and adds error detection data to each divided unit. It is a thing. An example of the recording data bit stream is shown in FIG.

Reference numeral 4 is a decoder, which is a buffer memory 41.
Error detector 42 and frame sync detector 43
, A controller 44, a decoding unit 45, and a frame memory 46.

The buffer memory 41 is a data streamer 2
This is for temporarily storing the compressed image data read from the recording medium 3. The error detection unit 42 detects whether or not an error has occurred for each compressed image data sectioned by predetermined error detection data. Assuming that the lower 8 bits of the sum of all the data in the delimited data are recorded as the error detection data, the error detection unit 42 calculates the sum for each delimited data,
When the lower 8 bits are different from the error detection data, it can be detected that an error has occurred in the range of the delimited data. The error occurrence information is output to the controller 44. When the frame sync detection unit 43 receives the data from which the error detection data has been deleted, that is, the original image compressed data bit stream from the error detection unit 42 and detects the code indicating the beginning of each frame, the frame sync detection unit 43 detects it to the controller 44. Output a signal. The decoding unit 45 is for decoding the image compressed data bit stream. The frame memory 46 stores display image data. When the controller 44 receives the error occurrence information from the error detection unit 42, the decoding unit 4
5 is instructed to interrupt the decoding process, and the frame memory 46 is instructed to hold the current display data.

Next, the operation will be described.

In the encoder 1, the input image data is encoded by the encoding unit 11, that is, compressed, and the compressed image data bit stream obtained by compression is predetermined by the error detection data addition unit 12. The length bit string is divided as one unit, and error detection data is added to each divided unit. The compressed image data to which the error detection data is added is the data streamer 2
Is recorded on the recording medium 3.

In the decoder 4, the compressed image data read from the recording medium 3 by the data streamer 2 is temporarily stored in the buffer memory 41. Then, the compressed image data in the buffer memory 41 is detected by the error detection unit 42 for each data sectioned by the predetermined error detection data. For example, when the lower 8 bits of the sum of all the data in the delimited data are recorded as the error detection data, the error detection unit 4
According to 2, the sum of each separated data is calculated, and it is determined whether or not the lower 8 bits are different from the error detection data. If the result of determination is that they are different, that is, if an error has occurred within the range of this delimited data, error occurrence information is output to the controller 44. Next, when the frame sync detection unit 43 detects a code indicating the beginning of each frame from the data obtained by deleting the error detection data from the error detection unit 42, that is, from the original image compressed data bit stream, it is detected by the controller 44. Output a signal. And the controller 44
When receiving the error occurrence information from the error detection unit 42, the command instructs the decoding unit 45 to suspend the decoding process and the frame memory 46 to hold the current display data. To do.

Then, when the frame sync detecting section 43 is informed to the controller 44 that the beginning of the frame has been detected, the controller 44 issues a command to the decoding section 45 to restart the decoding and the frame memory 46.
Command to update the data.

[0017]

As described above, according to the present invention,
Since it is configured as described above, the collapse of the reproduced image can be prevented.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a configuration of recorded compressed image data.

FIG. 3 is a block diagram showing a configuration of a conventional compressed image data recording / reproducing device.

[Explanation of symbols]

 1 Encoder 2 Data Streamer 3 Recording Medium 4 Decoder 11 Encoding Section 12 Error Detection Data Addition Section 41 Buffer Memory 42 Error Detection Section 43 Frame Sync Detection Section 44 Controller 45 Decoding Section 46 Frame Memory

Claims (1)

[Claims] 1. A recording means for recording a compressed image data bit stream obtained by compressing image data on a recording medium, and a reproducing means for reproducing the compressed image data recorded on the recording medium by the recording means. In the compressed image data recording / reproducing apparatus, the recording unit divides the compressed image data bit stream with a bit string having a predetermined length as one unit, and error detection data for each unit divided by the dividing unit. Error detecting data adding means for adding the error detecting data adding means for detecting whether or not an error has occurred in the read compressed image data for each unit, and the reproducing means. When an error is detected, a cancellation unit that cancels the decoding process, and if the decoding process is canceled by the cancellation unit, Compressed image data recording and reproducing apparatus characterized by comprising a holding means for holding the decoded image of No. process immediately before.