JPH11355720A - Image signal reproducing device and its method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce visual disturbance of a moving part especially on the occurrence of a correction impossible error. SOLUTION: A correction control section 27 controls information expansion processing of a discrete cosine transform DCT block in a SYNC block including a DCT block with a correction impossible error so as to be limited to specific data for each DCT block in the case that a correction impossible error is in existence in part of the DCT blocks of a luminance signal configuring the SYNC block and controls data of the DCT block with the correction impossible error and data of a color signal corresponding to the DCT block with the correction impossible error so that the data are replaced with data corresponding to a frame adjacent to the frame where the correction impossible error takes place.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for reproducing digital data from a recording medium on which digital data obtained by digitizing an image signal and performing information compression processing, error correction encoding processing, and the like are recorded. The present invention relates to an image signal reproducing apparatus and method for outputting an original image signal.

[0002]

2. Description of the Related Art A DV (or DVC) standard is used as a digital VTR (Video Tape Recorder) standard for digitizing an image signal, subjecting it to information compression processing, recording it on a magnetic tape as a recording medium, and reproducing the recorded information. (Known as HD-Digital VCR C
onference: Specification of Digtal VCR for Consume
r0-use (Jul. 1993)). The outline of the DV standard will be described below.

An image signal is composed of a luminance signal Y and a color difference signal Cr,
And 525 lines such as NTSC /
In the 60-field method, the number of effective pixels in the horizontal direction of the luminance signal Y is 720 pixels, the number of effective lines in the vertical direction is 480, and the color difference signals Cr and Cb are sampled at (4: 1: 1).
The number of effective pixels in the horizontal direction is 180 pixels, and the number of effective lines in the vertical direction is 480. Also P
In a so-called 625 line / 50 field system such as AL, the number of effective pixels in the horizontal direction of the luminance signal Y is 720, the number of effective lines in the vertical direction is 576, and the color difference signal is sampled at (4: 2: 0). For Cr and Cb, the number of effective pixels in the horizontal direction is 360 pixels, and the number of effective lines in the vertical direction is 288.

Image data is compressed by performing a DCT (Discrete Cosine Transform) operation by blocking these effective pixel data. A block for the DCT operation (hereinafter, referred to as a “DCT block”) is specifically configured such that each of the luminance signal Y and the color difference signals Cr and Cb is divided into eight horizontal pixels × eight vertical pixels for one frame pixel. Is done. Then, as shown in FIGS. 4A and 4B,
D of the luminance signal Y corresponding to the same area at the same position on the screen
A 6 DCT block including four CT blocks and one DCT block for each of the color difference signals Cb and Cr is called a “macro block”. Further, as shown in FIG. 5, a screen of one frame is divided into units of 27 macro blocks to form a super block. Then, one superblock is selected from each column in FIG. 5, one macroblock is extracted from each superblock, and one video segment is composed of five macroblocks. At the time of image information compression processing, control is performed such that the data amount is within a predetermined amount in video segment units. Further, the video segment containing the data amount in this way is again divided into macroblock units and arranged back to the original screen position, and when recording on a magnetic tape, the screen of one frame is divided into ten bands, The one data is recorded on one track.

The DCT operation includes a mode in which 8 × 8 DCT is performed with 8 horizontal pixels × 8 vertical pixels in frame units (hereinafter referred to as “still mode”), and a horizontal 8 pixels in field units.
There is provided a mode (hereinafter referred to as “motion mode”) for performing 8 × 4 DCT by 4 pixels × vertical pixels and calculating the sum and difference of DCT coefficients of two fields, and is adaptively switched at the time of encoding. It is possible. That is, if the movement between two fields is small, the former is selected, and if the movement is large, the latter is selected. The DCT coefficient obtained by the DCT operation is selected by selecting a quantization table so that the data amount after the quantization and the variable length coding is equal to or less than a predetermined value and the value closest to the predetermined value. Be transformed into

[0006] The variable length coding is performed on the AC component of the DCT coefficient, and the AC component is sequentially read from the low frequency component.
Two-dimensional Huffman coding is performed based on two pieces of information including a continuous number of 0s and non-zero values appearing after 0s. The data after the variable-length encoding is formatted as shown in FIG. 6, and as shown in FIG. 7, a sync block to which a sync word, an ID code, and a parity word (inner parity) for error correction are added. It is configured and recorded on a magnetic tape in units of sync blocks.

In FIG. 6, in the data area of each sync block, data necessary for decoding together with data after variable-length coding (Qn which is the number of the selected quantization table,
o, STA as error and concealment information, a class number taking a value according to the situation of the DCT block, and a DCT mode flag indicating which of the stationary mode and the motion mode is selected). . Here, concealing refers to replacing data using data of a previous frame or the like when an uncorrectable error occurs.

[0008] Information of one video segment is stored in five sync blocks. As described above, since one video segment is composed of five macroblocks, one sync block substantially corresponds to one macroblock. Since one macroblock is composed of four DCT blocks for the luminance signal Y and one DCT block for the color difference signals Cb and Cr, each DC component (DC) is stored in the DC area of FIG. AC) is, in principle, sequentially stored in the AC area corresponding to the same DCT block in the same sync block as the DC component. However, if this data amount becomes larger than the capacity of the allocated area, It is stored in a free AC area in the same sync block or in a free AC area in another sync block in the same video segment. Therefore, DC of one macroblock
The data is always stored at the same position in one macroblock, and the low frequency (low frequency component) data of the AC component is stored at a substantially fixed position, while the high frequency (high frequency component) data of the AC component is 1 It may not fit within one sync block.

[0009] The error correction coding is performed by using 1/1 of 270 video segments constituting one frame of video data.
0, ie, 138 sync blocks obtained by adding 3 sync blocks of video AUX (auxiliary information) to 135 sync blocks, and this is virtually 2
First, error correction coding such as Reed-Solomon coding (outer correction coding) is performed in the column direction to add 11 bytes of outer parity. When all the error correction coding in the column direction is completed, the sync blocks of the outer parity become 11 sync blocks. Error correction coding (inner correction coding) is performed in the row direction of 149 sync blocks obtained by adding 138 sync blocks of the video segment and the video AUX, and an inner parity of 8 bytes is added. Thus, video data for one track is configured (see FIG. 8A).

Next, error correction processing during reproduction in a conventional VTR will be described with reference to FIG. A 149 sync block is extracted from the reproduction data for one track, and the inner code decoding unit 101 first performs inner code decoding using the inner parity of each sync block in units of this. If the number of detected errors is larger than the preset error correction number, the erasure flag adding unit 104 adds an erasure flag to the sync block. And
The lost flag is written to the correction control unit 105, and the reproduced data is written to the memory 102.

Next, the outer code decoding section 103 performs outer code decoding using the outer parity and the erasure flag. As a result of decoding, if all 149 sync blocks can be corrected, the data of the corrected sync block is used as decoded data. If there is data that cannot be corrected by the outer code, a lost flag is added. The concealed sync block is made valid, and the sync block to which the erasure flag is added is concealed to be replaced with the sync block at the same position in the previous frame. Here, the data of the previous frame is stored in the memory 102. The output data of the outer code decoding unit 103 is subjected to the reverse information expansion processing at the time of recording and the like, and is returned to the original image signal and output.

[0012]

As described above, in the conventional VTR, when a large number of errors occur during reproduction and cannot be corrected, a sync block which is considered to have an error is located at the same position in the previous frame. Concealment to replace the sink block is performed. Since the sync block almost corresponds to a macroblock, some macroblocks are replaced in the screen with macroblocks of the previous frame. Although the above interference is small, there is a visually large interference in a portion where there is movement.

The present invention has been made in view of this point, and when an uncorrectable error occurs, an image signal reproducing apparatus and method capable of reducing visual disturbance particularly in a moving part. The purpose is to provide.

[0014]

In order to achieve the above object, according to the first aspect of the present invention, a luminance signal and a chrominance signal constituting an image signal are subjected to information compression processing in units of a predetermined pixel block. Perform error correction coding processing on the subsequent data, and record the processed data on a recording medium in units of sync blocks including data of a plurality of predetermined pixel blocks corresponding to each of the luminance signal and the chrominance signal. The image data reproducing apparatus which reproduces the digital data from the recording medium on which the digital data is recorded by the apparatus which performs the error correction decoding processing and the information expansion processing and outputs the original image signal constitutes the sync block. If there is an uncorrectable error in a part of the predetermined pixel block of the luminance signal, the system including the predetermined pixel block having the uncorrectable error is used. The information decompression process of the predetermined pixel block in the block is performed only for the specific data of each predetermined pixel block, and the data of the predetermined pixel block having the uncorrectable error and the predetermined pixel block having the uncorrectable error. And a correction control means for controlling so as to replace the data of the color signal corresponding to the frame with the corresponding data of the frame adjacent to the frame in which the uncorrectable error has occurred.

According to a second aspect of the present invention, a luminance signal and a chrominance signal constituting an image signal are subjected to information compression processing in units of a predetermined pixel block, and error-correction encoding processing is performed on the processed data. And the data after the processing is
The digital data is reproduced from a recording medium on which digital data is recorded by an apparatus for recording on a recording medium in units of sync blocks including data of a plurality of predetermined pixel blocks respectively corresponding to the luminance signal and the color signal, and error correction is performed. In an image signal reproducing device that performs a decoding process and an information decompression process and outputs an original image signal, when an uncorrectable error is found in a part of a predetermined pixel block of a luminance signal forming the sync block, the correction is performed. When the image content of the sync block including the predetermined pixel block having the uncorrectable error is similar to the image content of the corresponding sync block of the adjacent frame, all the data of the sync block including the predetermined pixel block having the uncorrectable error is deleted. The data is replaced with the data of the corresponding sync block of the adjacent frame, and the When the image content is not similar, the information decompression processing of the predetermined pixel block in the sync block including the predetermined pixel block having the uncorrectable error is performed for each predetermined pixel block. In addition to performing the processing on the unique data, the data of the predetermined pixel block having the uncorrectable error and the data of the color signal corresponding to the predetermined pixel block having the uncorrectable error are converted to the frame in which the uncorrectable error has occurred. Is controlled so as to be replaced with the corresponding data of the frame adjacent to.

According to a third aspect of the present invention, in the image signal reproducing apparatus according to the second aspect, the information compression processing is performed when a motion mode used when a change in image content is large or when a change in the image content is small. Is executed in any one of the still modes used for adding the mode information indicating the mode in which the information compression process was performed, and the correction control unit determines whether the image contents are similar to each other. The determination is performed by referring to the mode information.

According to a fourth aspect of the present invention, the luminance signal and the chrominance signal constituting the image signal are subjected to information compression processing in units of a predetermined pixel block, and error-correction coding processing is performed on the processed data. And the data after the processing is
The digital data is reproduced from a recording medium on which digital data is recorded by an apparatus for recording on a recording medium in units of sync blocks including data of a plurality of predetermined pixel blocks respectively corresponding to the luminance signal and the color signal, and error correction is performed. In an image signal reproducing method for performing decoding processing and information decompression processing and outputting an original image signal, when there is an uncorrectable error in a part of a predetermined pixel block of a luminance signal forming the sync block, the correction is performed. The information decompression process of the predetermined pixel block in the sync block including the predetermined pixel block having the uncorrectable error is performed only for the specific data of each predetermined pixel block, and the data of the predetermined pixel block having the uncorrectable error, The color signal data corresponding to the predetermined pixel block having the uncorrectable error is compared with the uncorrectable error. There and replaces the corresponding data of the frame adjacent to the frame that occurred.

According to a fifth aspect of the present invention, a luminance signal and a chrominance signal constituting an image signal are subjected to information compression processing in units of a predetermined pixel block, and error-correction coding processing is performed on the processed data. And the data after the processing is
The digital data is reproduced from a recording medium on which digital data is recorded by an apparatus for recording on a recording medium in units of sync blocks including data of a plurality of predetermined pixel blocks respectively corresponding to the luminance signal and the color signal, and error correction is performed. In an image signal reproducing method for performing decoding processing and information decompression processing and outputting an original image signal, when there is an uncorrectable error in a part of a predetermined pixel block of a luminance signal forming the sync block, the correction is performed. When the image content of the sync block including the predetermined pixel block having the uncorrectable error is similar to the image content of the corresponding sync block of the adjacent frame, all the data of the sync block including the predetermined pixel block having the uncorrectable error is deleted. The data is replaced with the data of the corresponding sync block of the adjacent frame, and the On the other hand, when the image content is not similar, the information decompression process of the predetermined pixel block in the sync block including the predetermined pixel block having the uncorrectable error is performed by adding unique data for each predetermined pixel block. In a limited manner, the data of the predetermined pixel block having the uncorrectable error and the color signal data corresponding to the predetermined pixel block having the uncorrectable error are converted into a frame adjacent to the frame in which the uncorrectable error has occurred. Is replaced with the corresponding data.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 is a block diagram showing a configuration of a main part of a digital image signal recording / reproducing apparatus according to an embodiment of the present invention. This apparatus is a VTR based on the DV standard described above. is there.

In FIG. 1, the recording system includes a blocking / shuffling unit 11, a compression processing unit 12, an error correction encoding unit 13, a sync block synthesis recording / modulation unit 14, a recording amplifier 15, a recording head 16 Are the main components, and perform the recording signal processing conforming to the DV standard. The blocking / shuffling unit 11 receives input raster scan image data (a luminance signal Y and two color difference signals Cb and Cb).
r), a block of 8 pixels vertically × 8 pixels horizontally (hereinafter referred to as “DCT block”) is composed of macro blocks (4 blocks of Y signal, 1 block of Cb signal, 1 block of Cr signal). ) Output in units. The compression processing unit 12 performs DCT (Discrete Cosine Transform) operation, quantization and variable length coding on input data, and the error correction coding unit 13 performs error correction coding and adds outer parity and inner parity. I do. The sync block synthesizing recording modulating unit 14 synthesizes a sync block constituting a small unit to be recorded on a magnetic tape, and performs modulation for recording on a magnetic tape.
The output data of the sync block synthesis recording modulation section 14 is amplified by the recording amplifier 15 and recorded by the magnetic head 16 on a magnetic tape 50 as a recording medium.

The reproduction system includes a reproduction head 21, a reproduction amplifier 22, a SYNC detection / reproduction demodulation unit 23, an error correction decoding unit 24, an expansion processing unit 25, and an output processing unit 26.
And the correction control unit 27 as main components. In addition,
The reproducing head 21 may be the same as the recording head 16. The data reproduced from the magnetic tape 50 by the reproducing head 21 is amplified by the reproducing amplifier 22 and output from the SYNC
The signal is input to the detection / reproduction / demodulation block 23. The SYNC detection / reproduction / demodulation block 23 detects a SYNC word from the reproduction data and performs demodulation corresponding to the modulation at the time of recording. The error correction decoding unit 24 performs an error detection / correction process using the inner parity and the outer parity, and the decompression processing unit 25 performs a process reverse to that at the time of recording, that is, a variable length decoding, an inverse quantization, and an inverse DCT operation. Are sequentially performed. The output processing unit 26 performs processing reverse to the shuffling at the time of recording to restore the pixel arrangement to the original, and outputs image data (the luminance signal Y and the color difference signals Cb and Cr). The correction control unit 27 is composed of a microcomputer or the like, and controls error correction and expansion output processing in the error correction decoding unit 24, the expansion processing unit 25, and the output processing unit 26, as described later. The output processing unit 26 includes two frame memories, is configured to store the data of the frame being reproduced and the data of the immediately preceding frame, and to appropriately select and output the data stored in both frames. ing.

The error correction decoding unit 24 is specifically configured as shown in FIG.
, The inner code decoding unit 31, the memory 32,
An outer code decoding unit 33, an erasure flag adding unit 34, and an outer code uncorrectable flag adding unit 35 are provided. In this configuration, the inner code decoding unit 31 performs inner code decoding using the inner parity in the same manner as in the related art, and performs correction when the number of detected errors is equal to or less than a predetermined error correction number set in advance. If the number of error corrections exceeds the predetermined number, the erasure flag indicating that the correction was not performed is added to the corresponding sync block by the erasure flag addition unit 34 without performing the correction (see FIG. 8B). A sync block with a cross indicates that the erasure flag has been added). At this time, the data subjected to the error correction by the inner parity is written to the memory 32, and the erasure flag is written to the correction control unit 27.

The outer code decoding unit 33 performs an outer code decoding process using the outer parity and the erasure flag in units of 149 sync blocks corresponding to one track of video data. As a result of decoding, if all outer parities can be corrected, the corrected data is output as decoded data. On the other hand, when there is an error that cannot be corrected, an outer code uncorrectable flag is added by the outer code uncorrectable flag adding unit 35 as shown in FIG. 8C, and this flag is held in the correction control unit 27. .

Before describing the correction and decompression output processing, the configuration of the video data format in the sync block shown in FIG. 6 will be described more specifically. The video data of one sync block is composed of 77 bytes, the first byte is composed of an STA flag, which is information of error and concealment, and a quantizer number QNo. The upper four bits of the second and third bytes are Is the DC component (9 bits) of the DCT block of one luminance signal Y in one macroblock,
A class number taking a value according to the situation of the DCT block;
A DCT mode flag indicating whether the DCT block is compressed in the motion mode or the still mode is stored. Lower 4 bits of third byte and fourth to first bits
In five bytes, in principle, AC components of the same luminance component are sequentially stored from a low-frequency component to a high-frequency component. However, the high-frequency component area (for example, the 14th and 15th bytes)
In some cases, data corresponding to another DCT block in the same sync block or data of another sync block in the same video segment may be stored. Hereinafter, the 16th to 29th bytes, 30th to 4th bytes in the same format
The 3rd byte and the 44th to 57th bytes store the data of the DCT block corresponding to the other luminance signal components in the same macroblock, and the 58th to 67th bytes and the 68th to 68th bytes
The 77th byte stores DCT block data of the color difference signals Cr and Cb. In the following description, the second
The 15th to 15th bytes are called an area B1, the 16th to 29th bytes are called an area B2, and the 30th to 43rd bytes are an area B3.
And the 44th to 57th bytes are called area B4,
The 8th to 57th bytes are called area B5, the 58th to 15th bytes are called area B5, and the 68th to 77th bytes are area B5.
Six.

The correction control unit 27 determines whether the data to which the outer code uncorrectable flag has been added (the byte specified by the erasure flag and the outer code uncorrectable flag) corresponds to the DCT block of the luminance signal Y (for example, the area B1). If the data is within the parentheses, correction processing is performed as follows. Hereinafter, the area B1
Only the case where there is an uncorrectable error will be described.

That is, for the error-free areas B2 to B6 in the sync block, the DC
The decoding process in the decompression processing unit 25 is controlled so that the decompression process is performed only in the unique region assigned to the T block.

Further, for other sync blocks belonging to the video segment including the sync block,
Control is performed so that decoding processing is performed only for data in each sync block. As a result, in a video segment in which an uncorrectable error has occurred, data in another sync block is not used for decoding data in one sync block. In other words, when data corresponding to one macro block cannot be stored in one sync block at the time of recording, the area of another sync block is diverted. Will not be used for decoding.

The correction control unit 27 further stores data (regions B2 to B3) corresponding to the DCT block of the error-free luminance signal Y.
4), and the data corresponding to the DCT block of the erroneous luminance signal Y (the data stored in the area B1) corresponds to the DCT block at the same position in the previous frame. The output control unit 26 is controlled so that the data is output after being replaced with data. Further, the color difference signals Cr and Cb are the DC values of the error-free luminance signal.
T block (data stored in areas B2 to B4)
Is output as it is, and the pixel data corresponding to the DCT block of the erroneous luminance signal (the data stored in the area B1) is replaced with the data at the same position in the previous frame and output. Control.

Referring to FIG. 3, a macro block is composed of four DCT blocks of the luminance signal Y and one DCT block of the color difference signals Cr and Cb. DCT blocks Y1, Y2, Y
3, Y4 is a set P of eight Cb and Cr pixels, respectively.
1, P2, P3, and P4. Here, Y1
Therefore, the Cb and Cr pixels of P1 are replaced with the pixel data of the previous frame. Also, the color difference signal C
Area B5 or B6 in which r and Cb are mainly stored
If there is an uncorrectable error, control is performed to perform concealment in the same manner as in the related art.

By controlling the correction processing as described above, the luminance signal and the color difference signal of the corresponding screen area of the DCT block of the luminance signal Y having an uncorrectable error are the same as the conventional data in the previous frame. Since the screen area corresponding to the DCT block of the luminance signal Y which is replaced but has no error is used with the data of the current frame, the area to be replaced with the data of the previous frame is more limited and can be made visually inconspicuous. it can.

In the above description, a case where an uncorrectable error is present in the area B1 is taken as an example.
And B2 have an uncorrectable error, the areas B3 and B2
4 is treated similarly as data corresponding to the luminance signal Y without error.

(Second Embodiment) In the first embodiment,
Although the same processing is performed regardless of the content of the recorded image, in the present embodiment, a stationary area in the screen corresponds to a sync block having an uncorrectable error as in the related art. The processing of replacing all the data of the macroblock with the data of the previous frame is performed, and the same processing as in the first embodiment is performed on the moving area.
The processing of the first embodiment takes into account that high frequency components may be lost because the sync block in which an uncorrectable error has occurred uses only data unique to each DCT block. It is.

More specifically, the correction control unit 27 determines whether the information of the current frame stored in the two frame memories in the output processing unit 26 and the previous frame are adjacent to the screen area where the uncorrectable error has occurred. The similarity is determined by comparing the information of the frame with the information of the frame, and when it is determined that the screen area has a high similarity and is a still screen area, the data of the macro block corresponding to the sync block in which the uncorrectable error has occurred is deleted. While controlling so that all frames are replaced and output, the similarity between the adjacent peripheral area of the screen area of the current frame where the uncorrectable error has occurred and the corresponding screen area of the previous frame is low, If it is determined, the same processing as in the first embodiment is performed. That is, the decoding process of the DCT block in the sync block including the DCT block having the uncorrectable error is performed only for the unique data of each DCT block, and the luminance signal Y having the uncorrectable error is decoded.
And the data of the color difference signals Cr and Cb corresponding to the DCT block are replaced with the corresponding data of the previous frame.

The above similarity determination uses information on pixels around a macroblock corresponding to a sync block in which an uncorrectable error has occurred. The other points are the same as those of the first embodiment.

According to the present embodiment, in a stationary area in a screen, all data of a macro block corresponding to an erroneous sync block is replaced with corresponding data of a previous frame. As a result, the high-frequency component of the AC component is not lost by the processing, and since there is no motion, there is no deterioration in the image quality when the data is replaced with the data of the previous frame, so that a good reproduction image quality can be obtained.
In addition, the same effect as in the first embodiment can be obtained in a moving area in the screen.

(Third Embodiment) In the second embodiment,
Although the similarity between the current frame and the previous frame is determined using the frame memory of the output processing unit 26, the present embodiment uses a DCT mode flag stored in each sync block instead. Thus, this determination is made. That is, when the DCT mode flag indicates that the data is compressed in the still mode, control is performed so that the data of the macro block corresponding to the sync block in which the uncorrectable error has occurred is completely replaced with the previous frame and output. Indicates that the data is compressed in the motion mode, the same processing as in the first embodiment is performed.

The other points are the same as those of the second embodiment. According to the present embodiment, it is necessary to perform a process for determining whether or not there is motion in the screen area where the uncorrectable error has occurred (the presence or absence of similarity between the screen content of the current frame and the screen content of the previous frame) at the time of reproduction. In addition, the configuration can be simplified.

(Other Embodiments) The present invention is not limited to the above-described embodiment, and various modifications are possible. For example, the replacement of the data is not limited to the data of the previous frame, but may be replaced with the data of the next frame. That is, the “adjacent frame” described in the claims corresponds to the frame immediately before or next to the current frame.

[0039]

As described above in detail, according to the first or fourth aspect of the present invention, when there is an uncorrectable error in a part of a predetermined pixel block of a luminance signal constituting a sync block, the correction is performed. The information decompression process of the predetermined pixel block in the sync block including the predetermined pixel block having the uncorrectable error is performed only on the unique data for each predetermined pixel block, and the data of the predetermined pixel block having the uncorrectable error, The color signal data corresponding to the predetermined pixel block having the uncorrectable error is replaced with the corresponding data of the frame adjacent to the frame in which the uncorrectable error has occurred. The screen area to be displayed is limited to a smaller area, and the visual disturbance of a moving part can be reduced.

According to the invention described in claim 2 or 5,
When the image content of the sync block including the predetermined pixel block having the uncorrectable error is similar to the image content of the corresponding sync block of the adjacent frame, the data of the sync block including the predetermined pixel block having the uncorrectable error is All the data is replaced with the data of the corresponding sync block of the adjacent frame, and normal information decompression processing is performed. On the other hand, when the image contents are not similar, the same processing as the invention according to claim 1 or 4 is performed. In a screen area where the motion of an image is large,
The same effects as those of the invention described in (1) can be obtained, and good image quality can be obtained in a screen area where the motion of the image is small.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an image signal recording / reproducing apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration of an error correction decoding unit in FIG. 1;

FIG. 3 is a diagram for explaining an error correction technique.

FIG. 4 is a diagram illustrating a macroblock.

FIG. 5 is a diagram for explaining a relationship among a macro block, a super block, and a video segment.

FIG. 6 is a diagram showing a format when recording encoded data.

FIG. 7 is a diagram showing a configuration of a sync block.

FIG. 8 is a diagram illustrating an error correction decoding process.

FIG. 9 is a diagram showing a configuration of a conventional error correction decoding unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 21 Reproduction head 24 Error correction decoding part 25 Decompression processing part 26 Output processing part 27 Correction control part (correction control means) 31 Inner code decoding part 32 Memory 33 Outer code decoding part 34 Erasure flag addition part 35 Outer code correction impossible Flag addition unit 50 Magnetic tape (recording medium)

Claims (5)

[Claims] An information compression process is performed on a luminance signal and a chrominance signal constituting an image signal in units of predetermined pixel blocks, and error-correction encoding is performed on the processed data. Reproducing the digital data from a recording medium on which digital data is recorded by a device that records on a recording medium in units of sync blocks including data of a plurality of predetermined pixel blocks corresponding to each of the luminance signal and the color signal, In an image signal reproducing apparatus that performs error correction decoding processing and information decompression processing and outputs an original image signal, when there is an uncorrectable error in a part of a predetermined pixel block of a luminance signal forming the sync block, The information decompression process of the predetermined pixel block in the sync block including the predetermined pixel block having the uncorrectable error is performed by the predetermined pixel block. Tsu performs is limited to specific data for each click, and data of a predetermined pixel block is the uncorrectable error,
A color signal data corresponding to the predetermined pixel block having the uncorrectable error, and correction control means for controlling so as to replace the data with a corresponding data of a frame adjacent to the frame in which the uncorrectable error has occurred. Image signal reproducing device. 2. An information compression process is performed on a luminance signal and a chrominance signal constituting an image signal in units of predetermined pixel blocks, and error-correction encoding is performed on the processed data. Reproducing the digital data from a recording medium on which digital data is recorded by a device that records on a recording medium in units of sync blocks including data of a plurality of predetermined pixel blocks corresponding to each of the luminance signal and the color signal, In an image signal reproducing apparatus that performs error correction decoding processing and information decompression processing and outputs an original image signal, when there is an uncorrectable error in a part of a predetermined pixel block of a luminance signal forming the sync block, The image content of the sync block including the predetermined pixel block having the uncorrectable error corresponds to the corresponding sync of the adjacent frame. When the image content is similar to the image content of the lock, all the data of the sync block including the predetermined pixel block having the uncorrectable error is replaced with the data of the corresponding sync block of the adjacent frame, and normal information decompression processing is performed. On the other hand, when the image contents are not similar, the information decompression process of the predetermined pixel block in the sync block including the predetermined pixel block having the uncorrectable error is limited to data unique to each predetermined pixel block. At the same time, the data of the predetermined pixel block having the uncorrectable error and the data of the color signal corresponding to the predetermined pixel block having the uncorrectable error correspond to the data of the frame adjacent to the frame in which the uncorrectable error has occurred. An image signal reproducing device, which controls so as to replace data. 3. The information compression process is executed in one of a motion mode used when a change in image content is large and a still mode used when a change in the image content is small, and the information compression is performed in any one of the modes. A method for adding mode information indicating whether processing has been performed, wherein the correction control unit determines whether or not the image contents are similar by referring to the mode information. 3. The image signal reproducing device according to 2. 4. An information compression process is performed on a luminance signal and a chrominance signal constituting an image signal in units of a predetermined pixel block, and error-correction encoding is performed on the processed data. Reproducing the digital data from a recording medium on which digital data is recorded by a device that records on a recording medium in units of sync blocks including data of a plurality of predetermined pixel blocks corresponding to each of the luminance signal and the color signal, In the image signal reproducing method of performing error correction decoding processing and information decompression processing and outputting an original image signal, when there is an uncorrectable error in a part of a predetermined pixel block of a luminance signal forming the sync block, The information decompression process of the predetermined pixel block in the sync block including the predetermined pixel block having the uncorrectable error is performed by the predetermined pixel block. Tsu performs is limited to specific data for each click, and data of a predetermined pixel block is the uncorrectable error,
A method of reproducing an image signal, comprising replacing data of a color signal corresponding to a predetermined pixel block having an uncorrectable error with data corresponding to a frame adjacent to a frame in which the uncorrectable error has occurred. 5. A luminance signal and a chrominance signal constituting an image signal are subjected to information compression processing in units of a predetermined pixel block, and error-correction encoding processing is performed on the processed data. Reproducing the digital data from a recording medium on which digital data is recorded by a device that records on a recording medium in units of sync blocks including data of a plurality of predetermined pixel blocks corresponding to each of the luminance signal and the color signal, In the image signal reproducing method of performing error correction decoding processing and information decompression processing and outputting an original image signal, when there is an uncorrectable error in a part of a predetermined pixel block of a luminance signal forming the sync block, The image content of the sync block including the predetermined pixel block having the uncorrectable error corresponds to the corresponding sync of the adjacent frame. When the image content of the lock is similar to the image content of the lock, all the data of the sync block including the predetermined pixel block having the uncorrectable error is replaced with the data of the corresponding sync block of the adjacent frame, and normal information decompression processing is performed. When the image contents are not similar, the information decompression process of the predetermined pixel block in the sync block including the predetermined pixel block having the uncorrectable error is performed only for data unique to each predetermined pixel block, Replacing data of a predetermined pixel block having an uncorrectable error and data of a color signal corresponding to the predetermined pixel block having the uncorrectable error with corresponding data of a frame adjacent to a frame in which the uncorrectable error has occurred. An image signal reproducing method characterized by the above-mentioned.