JP3849305B2 - Image signal reproducing apparatus and method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention digitizes an image signal, reproduces the digital data from a recording medium on which digital data obtained by performing information compression processing, error correction coding processing, etc. is recorded, and outputs the original image signal The present invention relates to an image signal reproducing apparatus and method.
[0002]
[Prior art]
The DV standard (or called the DVC standard) is known as a digital VTR (video tape recorder) standard for digitizing an image signal, recording information on a magnetic tape as a recording medium, and reproducing the recorded information. (For example, HD-Digital VCR Conference: Specification of Digital VCR for Consumer 0-use (Jul. 1993)). The outline of the DV standard will be described below.
[0003]
The image signal is composed of a luminance signal Y and color difference signals Cr and Cb. In a so-called 525/60 field system such as NTSC, the image signal is sampled at (4: 1: 1) and the horizontal direction of the luminance signal Y is effective. The number of pixels is 720, the number of effective lines in the vertical direction is 480, and the color difference signals Cr and Cb each have 180 effective pixels in the horizontal direction and 480 effective lines in the vertical direction. In the so-called 625/50 field system such as PAL, 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 576, and the color difference is sampled at (4: 2: 0). For the signals 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.
[0004]
By compressing these effective pixel data and performing DCT (Discrete Cosine Transform) calculation, the image information is compressed. A block for DCT calculation (hereinafter referred to as “DCT block”) is specifically configured by dividing each of the luminance signal Y and the color difference signals Cr and Cb into 8 horizontal pixels × 8 vertical pixels for one frame of pixels. Is done. Then, as shown in FIGS. 4A and 4B, it includes four DCT blocks of the luminance signal Y corresponding to the same area at the same position on the screen and one DCT block of the color difference signals Cb and Cr. The 6DCT block is called a “macroblock”. Further, as shown in FIG. 5, the screen of one frame is divided in units of 27 macro blocks to form a super block. Then, one super block is selected from each column in FIG. 5, one macro block is extracted from each super block, and one video segment is composed of five macro blocks. At the time of image information compression processing, control is performed so that the data amount is within a predetermined amount for each video segment. Furthermore, the video segment containing the amount of data in this way is divided again into macroblock units and rearranged to the original screen position, and when recording on magnetic tape, the screen of one frame is divided into 10 bands, The one data is recorded on one track.
[0005]
The DCT calculation includes a mode in which 8 × 8 DCT is performed with 8 horizontal pixels × vertical 8 pixels in frame units (hereinafter referred to as “still mode”), and 8 × 4 DCT with 8 horizontal pixels × vertical 4 pixels in field units. And a mode that takes the sum and difference of the DCT coefficients of the two fields (hereinafter referred to as “motion mode”) is provided, and can be switched adaptively during encoding. That is, the former is selected when the motion between the two fields is small, and the latter is selected when the motion is large. The DCT coefficient obtained by the DCT calculation is selected by selecting a quantization table so that the amount of data after quantization and variable length coding is equal to or less than a predetermined value and closest to the predetermined value. It becomes.
[0006]
The variable length coding is performed on the alternating current component of the DCT coefficient. The alternating current component is sequentially read out from the low frequency component, and the two-dimensional Huffman coding is performed by using two pieces of information of the consecutive number of 0 and the non-zero value appearing after 0. The data after the variable length coding is formatted as shown in FIG. 6, and further, 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. And is recorded on the magnetic tape in units of sync blocks.
[0007]
In FIG. 6, in the data area of each sync block, parameters necessary for decoding together with data after variable length coding (number of selected quantization table Qno, error and conceal information STA, DCT block of A class number that takes a value according to the situation, and a DCT mode flag indicating whether the stationary mode or the motion mode is selected are also stored. Here, concealment refers to replacing data using data such as the previous frame 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 is substantially equivalent to one macroblock. Since one macro block is composed of four DCT blocks of the luminance signal Y and one DCT block of the color difference signals Cb and Cr, each direct current component (DC) is stored in the DC region of FIG. AC) is stored in sequence in the AC area corresponding to the same DCT block in the same sync block as the DC component in principle, but when this data amount exceeds 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 of another sync block in the same video segment. Therefore, the DC data of one macroblock is always stored at the same position of one macroblock, and the low frequency (low frequency component) data of the AC component is stored at a substantially fixed position, but the high frequency of the AC component ( There is a possibility that the data of the high frequency component) is not contained in one sync block.
[0009]
In error correction coding, 27 video segments that are 1/10 of 270 video segments constituting one frame of video data, that is, 138 sync blocks obtained by adding 3 sync blocks of video AUX (auxiliary information) to 135 sync blocks, This is virtually arranged in two dimensions, and first, error correction coding (outer correction coding) such as Reed-Solomon 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 outer parity sync block becomes 11 sync blocks. Error correction coding (inner correction coding) is performed in the row direction of the 149 sync block obtained by adding 138 sync blocks of the video segment and video AUX to this, and 8 bytes of inner parity are added. Thus, video data for one track is constructed (see FIG. 8A).
[0010]
Next, error correction processing during reproduction in a conventional VTR will be described with reference to FIG. 149 sync blocks are extracted from the reproduction data for one track, and by using this as a unit, the inner code decoding unit 101 first performs inner code decoding using the inner parity of each sync block. If there are more errors detected than the preset number of error corrections, the erasure flag adding unit 104 adds an erasure flag to the sync block. Then, the erasure flag is written in the correction control unit 105, and the reproduction data is written in the memory 102.
[0011]
Next, the outer code decoding unit 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, an erasure flag is added. The sync block to which the unused sync block is made valid and the erasure flag is added is concealed to replace 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 reverse information expansion processing at the time of recording, etc., returned to the original image signal, and output.
[0012]
[Problems to be solved by the invention]
As described above, in the conventional VTR, when many errors occur during reproduction and correction becomes impossible, concealment is performed in which a sync block considered to have an error is replaced with a sync block at the same position in the previous frame. . Since the sync block almost corresponds to the macro block, a part of the macro block is replaced with the macro block of the previous frame in the screen. There is little obstruction on the top, but it becomes a large obstruction on the part where there is movement.
[0013]
The present invention has been made paying attention to this point, and provides an image signal reproducing apparatus and method capable of reducing visual disturbance particularly in a moving part when an uncorrectable error occurs. For the purpose.
[0014]
[Means for Solving the Problems]
  In order to achieve the above object, according to the first aspect of the present invention, the luminance signal and the color signal constituting the image signal are each subjected to information compression processing in units of a predetermined pixel block, and an error correction code is applied to the processed data. Digital data is recorded by a device that performs data processing and records the processed data on a recording medium in units of sync blocks including data of a plurality of predetermined pixel blocks corresponding to the luminance signal and the color signal, respectively. Play back the digital data from a recording mediumPlayback means to,Of the reproduced digital dataError correction decoding processError correction decoding processing means for performing the error correction decoding processing of the digital dataPerform information expansion processingInformation expansion processing means,Performs the reverse process of shuffling during recording on the digital data that has undergone information decompression to return the pixel position to the original position,Output the original image signalOutput processing meansIn the image signal reproducing apparatus, when there is an uncorrectable error in a part of the predetermined pixel block of the luminance signal constituting the sync block, the predetermined pixel block in the sync block including the predetermined pixel block having the uncorrectable error is detected. The information decompression process is limited to unique data for each predetermined pixel block.To control the information expansion processing meansAnd data of a predetermined pixel block having the uncorrectable error and color signal data corresponding to the predetermined pixel block having the uncorrectable error, and corresponding data of a frame adjacent to the frame in which the uncorrectable error has occurred. To replaceThe output processing meansIt has a correction control means for controlling.
[0015]
  According to the second aspect of the present invention, the luminance signal and the color signal constituting the image signal are each subjected to information compression processing in units of a predetermined pixel block, and the error correction coding processing is performed on the processed data, The digital data is recorded from a recording medium on which digital data is recorded by a device for recording the processed data on a recording medium in units of sync blocks including data of a plurality of predetermined pixel blocks corresponding to the luminance signal and the color signal, respectively. PlayPlayback means to,Of the reproduced digital dataError correction decoding processError correction decoding processing means for performing the error correction decoding processing of the digital dataPerform information expansion processingInformation expansion processing means,Performs the reverse process of shuffling during recording on the digital data that has undergone information decompression to return the pixel position to the original position,Output the original image signalOutput processing meansIn the image signal reproduction device, when there is an uncorrectable error in a part of the predetermined pixel block of the luminance signal constituting the sync block, the image content of the sync block including the predetermined pixel block having the uncorrectable error is the adjacent When the image content of the corresponding sync block of the frame to be similar is similar to that of the sync block including the predetermined pixel block having the uncorrectable error, the data is replaced with the data of the corresponding sync block of the adjacent frame. To perform information expansion processingThe information decompression processing meansOn the other hand, when the image contents are 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 limited to unique data for each predetermined pixel block.To control the information expansion processing meansAnd data of a predetermined pixel block having the uncorrectable error and color signal data corresponding to the predetermined pixel block having the uncorrectable error, and corresponding data of a frame adjacent to the frame in which the uncorrectable error has occurred. To replaceThe output processing meansControlHas correction control meansIt is characterized by that.
[0016]
According to a third aspect of the present invention, in the image signal reproduction device according to the second aspect, the information compression processing is used when the motion mode used when the change in the image content is large or when the change in the image content is small. It is executed in any of the still modes and adds mode information indicating in which mode the information compression processing has been performed, and the correction control means determines whether or not the image contents are similar. This is performed by referring to the mode information.
[0017]
In the invention according to claim 4, the luminance signal and the color signal constituting the image signal are each subjected to information compression processing in units of a predetermined pixel block, the error-correction coding processing is performed on the processed data, The digital data is recorded from a recording medium on which digital data is recorded by a device for recording the processed data on a recording medium in units of sync blocks including data of a plurality of predetermined pixel blocks corresponding to the luminance signal and the color signal, respectively. In an image signal reproduction method for performing error correction decoding processing and information expansion processing to output an original image signal, there is an uncorrectable error in a part of a predetermined pixel block of a luminance signal constituting the sync block In this case, the information decompression process of the predetermined pixel block in the sync block including the predetermined pixel block having the uncorrectable error is This is limited to specific data for each fixed pixel block, and 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 cannot be corrected. It is characterized in that it is replaced with data corresponding to a frame adjacent to the frame in which an error has occurred.
[0018]
According to the fifth aspect of the present invention, information compression processing is performed for each of the luminance signal and the color signal constituting the image signal in units of predetermined pixel blocks, and error correction coding processing is performed on the processed data. The digital data is recorded from a recording medium on which digital data is recorded by a device for recording the processed data on a recording medium in units of sync blocks including data of a plurality of predetermined pixel blocks corresponding to the luminance signal and the color signal, respectively. In an image signal reproduction method for performing error correction decoding processing and information expansion processing to output an original image signal, there is an uncorrectable error in a part of a predetermined pixel block of a luminance signal constituting the sync block In this case, the image content of the sync block including the predetermined pixel block having the uncorrectable error corresponds to the adjacent frame. When the image content of the sync block is similar, the data of the sync block including the predetermined pixel block having the uncorrectable error is all 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 processing of the predetermined pixel block in the sync block including the predetermined pixel block having the uncorrectable error is limited to specific data for each predetermined pixel block. 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 the corresponding data of the frame adjacent to the frame where the uncorrectable error has occurred. It is characterized by replacing.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
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 conforming to the above-described DV standard.
[0020]
1, the recording system mainly includes a blocking / shuffling unit 11, a compression processing unit 12, an error correction coding unit 13, a sync block synthesis recording modulation unit 14, a recording amplifier 15, and a recording head 16. As a component, recording signal processing conforming to the DV standard is performed. The blocking / shuffling unit 11 is a vertical 8 pixel × horizontal 8 pixel block (hereinafter referred to as a “DCT block”) from input raster scan image data (image data corresponding to the luminance signal Y and the two color difference signals Cb and Cr). The DCT block is output in units of macro blocks (4 Y signal blocks, 1 Cb signal block, 1 Cr signal block). The compression processing unit 12 performs DCT (discrete cosine transform) operation, quantization, and variable length coding on the 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 synthesis record modulation unit 14 synthesizes sync blocks constituting a small unit to be recorded on the magnetic tape and performs modulation for recording on the magnetic tape. The output data of the sync block synthesis record modulation unit 14 is Amplified by the recording amplifier 15 and recorded on a magnetic tape 50 as a recording medium by the magnetic head 16.
[0021]
  The reproduction system mainly 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, an output processing unit 26, and a correction control unit 27. It is a component. Note that the reproducing head 21 may be the same as the recording head 16. Data reproduced from the magnetic tape 50 by the reproducing head 21 is amplified by the reproducing amplifier 22 and input to the SYNC detection reproducing demodulation block 23. SYNC detection reproduction demodulationPart23 detects the 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 error detection / correction processing using inner parity and outer parity, and the expansion processing unit 25 performs processing reverse to that at the time of recording, that is, variable length decoding, inverse quantization, and inverse DCT calculation. Are performed sequentially. The output processing unit 26 performs processing reverse to the shuffling at the time of recording, restores the pixel arrangement, and outputs image data (luminance signal Y and color difference signals Cb, 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 will be described later. The output processing unit 26 includes two frame memories, and is configured to store the data of the frame being reproduced and the data of the previous frame, and appropriately select and output the data stored in both. ing.
[0022]
Specifically, as shown in FIG. 2, the error correction decoding unit 24 includes an inner code decoding unit 31, a memory 32, an outer code decoding unit 33, an erasure flag adding unit 34, and an outer code uncorrectable. And a flag adding unit 35. In this configuration, the inner code decoding unit 31 performs inner code decoding using inner parity as in the conventional example, and corrects the error when the number of detected errors is equal to or less than a predetermined error correction number set in advance. If the number exceeds the predetermined error correction number, the erasure flag indicating that the correction could not be performed is added to the corresponding sync block by the erasure flag adding unit 34 without performing correction (in FIG. 8B). The sync block marked with x indicates that the disappearance flag has been added). At this time, the data subjected to the error correction by the inner parity is written in the memory 32, and the erasure flag is written in the correction control unit 27.
[0023]
The outer code decoding unit 33 performs outer code decoding processing using the outer parity and the erasure flag in units of 149 sync blocks corresponding to video data for one track. As a result of decoding, if all the outer parities can be corrected, the corrected data is output as decoded data. On the other hand, if 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. .
[0024]
Here, before explaining 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 that is error and concealment information, and a quantizer number QNo, and the upper 4 bits of the second and third bytes. Is a DC component (9 bits) of a DCT block of one luminance signal Y in one macro block, a class number that takes a value according to the state of the DCT block, and whether the DCT block is compressed in motion mode or still mode And a DCT mode flag indicating whether or not compression has been performed. In the lower 4 bits of the third byte and the 4th to 15th bytes, in principle, AC components of the same luminance component are sequentially stored from the low frequency component to the high frequency component. However, data corresponding to other DCT blocks in the same sync block or data of other sync blocks in the same video segment may be stored in the high frequency component area (for example, the 14th and 15th bytes). is there. Hereinafter, in the same format, the 16th to 29th bytes, the 30th to 43rd bytes, and the 44th to 57th bytes store DCT block data corresponding to other luminance signal components in the same macroblock, and The 58th to 67th bytes and the 68th to 77th bytes store DCT block data of the color difference signals Cr and Cb. In the following description, the 2nd to 15th bytes are referred to as area B1, the 16th to 29th bytes are referred to as area B2, the 30th to 43rd bytes are referred to as area B3, and the 44th to 57th bytes are referred to as area B4. The 58th to 57th bytes are referred to as a region B5, the 58th to 15th bytes are referred to as a region B5, and the 68th to 77th bytes are referred to as a region B6.
[0025]
The correction control unit 27 includes the data (byte specified by the erasure flag and the outer code uncorrectable flag) to which the outer code uncorrectable flag is added in the region (for example, the region B1) corresponding to the DCT block of the luminance signal Y. If it is data, correction processing is performed as follows. Hereinafter, description will be made assuming that there is an uncorrectable error only in the area B1.
[0026]
That is, the decoding process in the expansion processing unit 25 is performed so that the error-free regions B2 to B6 in the sync block are expanded only in the unique region assigned to the DCT block corresponding to each region. Control.
[0027]
Further, control is performed so that the other sync blocks belonging to the video segment including the sync block are subjected to decoding processing only for the data in each sync block. As a result, in the video segment in which an uncorrectable error has occurred, the data related to the other sync blocks is not used for decoding the data in one sync block. That is, when data corresponding to one macro block cannot be stored in one sync block at the time of recording, the area of the other sync block is diverted, but the data passed to the other sync block in this way Will not be used for decryption.
[0028]
  Further, the correction control unit 27 outputs the data corresponding to the DCT block of the luminance signal Y without error (data stored in the areas B2 to B4) as it is, and the data corresponding to the DCT block of the luminance signal Y with error. (Data stored in the area B1) is output so that the data corresponding to the DCT block at the same position in the previous frame is output.processingThe unit 26 is controlled. As for the color difference signals Cr and Cb, the pixel data corresponding to the DCT block of the luminance signal without error (data stored in the regions B2 to B4) is output as it is, and the DCT block (region of the erroneous luminance signal) The pixel data corresponding to (the data stored in B1) is controlled so as to be replaced with the data at the same position in the previous frame and output.
[0029]
This will be described with reference 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. , Y2, Y3, and Y4 correspond to a set of eight Cb and Cr pixels P1, P2, P3, and P4, respectively. Here, since there is an error in Y1, the Cb and Cr pixels of P1 are replaced with the pixel data of the previous frame.
If there is an uncorrectable error in the area B5 or B6 where the color difference signals Cr and Cb are mainly stored, control is performed so that concealment is performed as in the conventional case.
[0030]
By controlling the correction process as described above, the luminance signal and the color difference signal in the screen area corresponding to the DCT block of the luminance signal Y having an uncorrectable error are replaced with the data of the previous frame as in the conventional case. Since the data of the current frame is used for the screen area corresponding to the DCT block of the luminance signal Y without error, the area replaced with the data of the previous frame is more limited and can be made visually inconspicuous.
[0031]
In the above description, the case where there is an uncorrectable error in the area B1 is taken as an example. However, for example, when there is an uncorrectable error in the areas B1 and B2, the data stored in the areas B3 and B4 are The same processing is performed by treating as data corresponding to the luminance signal Y without error.
[0032]
(Second Embodiment)
In the first embodiment, the same processing is performed regardless of the contents of the recorded image. However, in this embodiment, an error that cannot be corrected in a stationary area in the screen is the same as in the past. The macro block data corresponding to a certain sync block is completely replaced with the data of the previous frame, and the same process as that of the first embodiment is performed for a region with motion. The processing of the first embodiment takes into account that high frequency components may be lost because only the data specific to each DCT block is used in the sync block in which an uncorrectable error has occurred. It is.
[0033]
Specifically, the correction control unit 27, for the adjacent peripheral region of the screen region where an uncorrectable error has occurred, information on the current frame and information on the previous frame stored in the two frame memories in the output processing unit 26 And the similarity is determined, and if it is determined that the screen area has a high similarity and is still, all the data of the macroblock corresponding to the sync block in which the uncorrectable error has occurred is stored in the previous frame. When control is performed so that the output is replaced, but the adjacent peripheral area of the screen area of the current frame in which an uncorrectable error has occurred is not similar to the screen area of the corresponding previous frame, and it is determined that the area is moving Performs the same processing as in the first embodiment. That is, the decoding process of the DCT block in the sync block including the DCT block having the uncorrectable error is limited to the unique data for each DCT block, and the data of the DCT block of the luminance signal Y having the uncorrectable error is performed. Then, control is performed to replace the data of the color difference signals Cr and Cb corresponding to the DCT block with the corresponding data of the previous frame.
[0034]
Note that the similarity determination uses information on pixels around the macroblock corresponding to the sync block in which an uncorrectable error has occurred.
Except for the points described above, the second embodiment is the same as the first embodiment.
[0035]
According to the present embodiment, in the still area in the screen, all the data of the macroblock corresponding to the erroneous sync block is replaced with the corresponding data of the previous frame, so the processing of the first embodiment The high-frequency component of the alternating current component is not lost, and there is no movement, so there is no deterioration of the image quality when replaced with the data of the previous frame, so that a good reproduction image quality can be obtained. Further, the same effect as that of the first embodiment can be obtained in a region with movement in the screen.
[0036]
(Third embodiment)
In the second embodiment, the similarity between the current frame and the previous frame is determined using the frame memory of the output processing unit 26. However, in the present embodiment, the similarity is stored in each sync block instead. This determination is performed using the DCT mode flag. That is, when the DCT mode flag indicates that compression is performed in the still mode, control is performed so that the macroblock data corresponding to the sync block in which an uncorrectable error has occurred is completely replaced with the previous frame and output. Indicates that compression is performed in the motion mode, the same processing as in the first embodiment is performed.
[0037]
Except for the points described above, the second embodiment is the same as the second embodiment.
According to the present embodiment, it is necessary to perform a process for determining whether or not there is a motion in the screen area where an 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) during playback. Therefore, the configuration can be simplified.
[0038]
(Other embodiments)
The present invention is not limited to the embodiment described above, and various modifications can be made. For example, the replacement of data is not limited to the data of the previous frame, and may be replaced with the data of the next frame. That is, the “adjacent frame” described in the claims corresponds to a frame one frame before or one frame after the current frame.
[0039]
【The invention's effect】
As described above in detail, according to the invention described in claim 1 or 4, when there is an uncorrectable error in a part of the predetermined pixel block of the luminance signal constituting the sync block, the predetermined error with the uncorrectable error is present. Information decompression processing of a predetermined pixel block in a sync block including a pixel block is performed only on unique data for each predetermined pixel block, and the data of the predetermined pixel block having the uncorrectable error and the uncorrectable error are Since the color signal data corresponding to a certain predetermined pixel block is replaced with the data corresponding to the frame adjacent to the frame in which the uncorrectable error has occurred, the screen area where the replacement with the data of the adjacent frame is performed, Limited to a narrower range, it is possible to reduce the visual disturbance especially in a moving part.
[0040]
According to the invention of claim 2 or 5, when the image content of the sync block including the predetermined pixel block having an uncorrectable error is similar to the image content of the corresponding sync block of the adjacent frame, the correction is not possible. When all the data of the sync block including the predetermined pixel block having an error is replaced with the data of the sync block corresponding to the adjacent frame and the normal information decompression process is performed, the image contents are not similar. Since processing similar to that of the invention described in 1 or 4 is performed, an effect similar to that of the invention described in claim 1 or 4 can be obtained in a screen area in which image movement is large, and further, a screen in which image movement is small. Good image quality can be obtained in the region.
[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 for explaining a macro block;
FIG. 5 is a diagram for explaining a relationship between a macro block, a super block, and a video segment.
FIG. 6 is a diagram showing a format for recording encoded data.
FIG. 7 is a diagram illustrating a configuration of a sync block.
FIG. 8 is a diagram for explaining error correction decoding processing;
FIG. 9 is a diagram illustrating a configuration of a conventional error correction decoding unit.
[Explanation of symbols]
  21 Playback head(Reproduction means)
  22 Playback amplifier (reproduction means)
  23 SYNC detection reproduction demodulation unit (reproduction means)
  24 Error correction decoder(Error correction decoding processing means)
  25 Decompression processing unit(Information expansion processing means)
  26 Output processing section(Output processing means)
  27 Correction control unit (correction control means)
  31 Inner code decoding unit
  32 memory
  33 Outer code decoding unit
  34 Loss flag addition part
  35 Outer code uncorrectable flag adding part
  50 Magnetic tape (recording medium)

Claims (5)

The luminance signal and the color signal constituting the image signal are each subjected to information compression processing in units of predetermined pixel blocks, error-correction coding processing is performed on the processed data, and the processed data is converted into the luminance signal. reproducing means for reproducing said digital data from a recording medium on which digital data is recorded by a plurality of apparatus for recording on a recording medium the sync block as a unit including the data of a predetermined pixel block and corresponding to the respective color signals, are reproduced and an error correction decoding processing means for error-correction decoding processing of digital data, and an error correction decoding process by the line power sale information decompression means information expansion processing of digital data, to the information expansion processing digital data is back into position pixel position by performing a shuffling and inverse processing at the time of recording Te, out of outputting the original image signal An image signal reproducing apparatus and processing means,
When there is an uncorrectable error in a part of the predetermined pixel block of the luminance signal constituting the sync block, information decompression processing of the predetermined pixel block in the sync block including the predetermined pixel block having the uncorrectable error is performed in a predetermined manner. Controlling the information expansion processing means so as to limit the data to unique data for each pixel block;
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 replaced with the corresponding data of the frame adjacent to the frame where the uncorrectable error has occurred. An image signal reproducing apparatus comprising correction control means for controlling the output processing means as described above . The luminance signal and the color signal constituting the image signal are each subjected to information compression processing in units of predetermined pixel blocks, error-correction coding processing is performed on the processed data, and the processed data is converted into the luminance signal. reproducing means for reproducing said digital data from a recording medium on which digital data is recorded by a plurality of apparatus for recording on a recording medium the sync block as a unit including the data of a predetermined pixel block and corresponding to the respective color signals, are reproduced and an error correction decoding processing means for error-correction decoding processing of digital data, and an error correction decoding process by the line power sale information decompression means information expansion processing of digital data, to the information expansion processing digital data is back into position pixel position by performing a shuffling and inverse processing at the time of recording Te, out of outputting the original image signal An image signal reproducing apparatus and processing means,
When there is an uncorrectable error in a part of the predetermined pixel block of the luminance signal constituting the sync block, the image content of the sync block including the predetermined pixel block with the uncorrectable error is a sync corresponding to the adjacent frame. When it is similar to the image content of the block, 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. While controlling the information decompression processing means ,
When the image content is not similar, the information decompression processing of a given pixel block in the sync block containing a predetermined pixel block is uncorrectable errors, the information to perform is limited to specific data for each predetermined pixel block While controlling the expansion processing means, 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 adjacent to the frame in which the uncorrectable error has occurred. An image signal reproducing apparatus comprising correction control means for controlling the output processing means so as to replace the corresponding data of a frame to be processed . The information compression process is executed in either the motion mode used when the change in the image content is large or the still mode used when the change in the image content is small, and in which mode the information compression process is performed. 3. The image according to claim 2, wherein the correction control means determines whether or not the image contents are similar by referring to the mode information. Signal reproduction device. The luminance signal and the color signal constituting the image signal are each subjected to information compression processing in units of predetermined pixel blocks, error-correction coding processing is performed on the processed data, and the processed data is converted into the luminance signal. The digital data is reproduced from the recording medium on which the digital data is recorded by the apparatus for recording on the recording medium in units of sync blocks including data of a plurality of predetermined pixel blocks corresponding to the color signals and error correction decoding processing. And an image signal reproduction method for performing information expansion processing and outputting the original image signal,
When there is an uncorrectable error in a part of the predetermined pixel block of the luminance signal constituting the sync block, information decompression processing of the predetermined pixel block in the sync block including the predetermined pixel block having the uncorrectable error is performed in a predetermined manner. While limiting to unique data for each pixel block,
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 replaced with the corresponding data of the frame adjacent to the frame where the uncorrectable error has occurred. An image signal reproducing method characterized by the above. The luminance signal and the color signal constituting the image signal are each subjected to information compression processing in units of predetermined pixel blocks, error-correction coding processing is performed on the processed data, and the processed data is converted into the luminance signal. The digital data is reproduced from the recording medium on which the digital data is recorded by the apparatus for recording on the recording medium in units of sync blocks including data of a plurality of predetermined pixel blocks corresponding to the color signals and error correction decoding processing. And an image signal reproduction method for performing information expansion processing and outputting the original image signal,
When there is an uncorrectable error in a part of the predetermined pixel block of the luminance signal constituting the sync block, the image content of the sync block including the predetermined pixel block with the uncorrectable error is a sync corresponding to the adjacent frame. When similar to the image content of the block, the data of the sync block including the predetermined pixel block having the uncorrectable error is all replaced with the data of the corresponding sync block of the adjacent frame, and the normal information expansion process is performed. ,
When the image contents are 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 limited to unique data for each predetermined pixel block, and the correction is performed. Replacing the data of a predetermined pixel block having an uncorrectable error and the color signal data corresponding to the predetermined pixel block having an uncorrectable error with corresponding data of a frame adjacent to the frame in which the uncorrectable error has occurred. A characteristic image signal reproducing method.

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