JP3610593B2 - Formatting method of digital data recording medium - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a method for formatting a digital data recording medium suitable for a digital VTR, for example.
[0002]
[Prior art]
For example, in a digital VTR, conventionally, digital data obtained by A / D converting a video signal has been recorded as it is. For this reason, for troubles unavoidable for VTR such as dropout, the digital data is scrambled at the time of recording and descrambled at the time of reproduction, and the dropout pixel is interpolated from surrounding pixels to eliminate the trouble. It was possible.
[0003]
By the way, in recent years, research on compression has been advanced in image processing, and recording in the digital VTR by applying such image compression has been studied. However, in that case, the image compression uses the time-series correlation of the surrounding pixels. On the other hand, when the scramble is performed, the time-series correlation is lost. That is, scrambling that has been conventionally used as a countermeasure for dropout is incompatible with image compression, and cannot be scrambled to perform image compression.
[0004]
Therefore, for example, as shown in FIG. 6, the digital data obtained by A / D conversion of the video signal is separated into two sets of ○ and ● every other sample, and each of the separated sets is compressed, and the compressed digital It has been proposed to record data on different tracks for each set. According to this, although the compression rate decreases, for example, even if all the tracks on which the data of ○ is recorded are lost, if the track on which the data of ● is reproduced, the data of ○ is Interpolation from surrounding pixels is possible.
[0005]
However, when recording is performed by applying such image compression, the compression is performed on, for example, a block composed of 64 digital data of 8 × 8, for example, as shown by being surrounded by a broken line in FIG. For this reason, if there is an error in the compressed data for each block, this error will spread to the entire block when compression is restored, and the image quality will be significantly degraded.
[0006]
Therefore, when the above-described interpolation is performed, half of the pixels in one block are interpolated, so that deterioration in image quality is inevitable. Therefore, when recording is performed by applying the above-described image compression, it is necessary to prevent errors from remaining as much as possible, and an extremely powerful error correction means is provided as compared with a conventional apparatus that does not perform compression. There was a need.
[0007]
In order to provide a powerful error correction means, it is conceivable to increase the error correction capability by increasing the number of check codes for error correction, for example. However, increasing the number of check codes within a limited track length has a problem in that the redundancy of data is increased, the shortest recording wavelength is shortened, and the error rate of the original reproduction signal is deteriorated.
[0008]
Furthermore, conventionally, as shown in FIG. 7B, compressed data obtained by compressing the above-mentioned one block of data is arranged two-dimensionally, and an outer code check code for error correction is generated for the outer code series. Similarly, an inner code check code for error correction is generated for the inner code series.
[0009]
Then, with respect to the outer code sequence including the check code generated in this way, recording is performed so that one track is formed by the two sequences of the outer code sequence (bold line) as shown in FIG. 7C. Was done. Note that the two sets of data ○ and ● described above are alternately recorded on each track.
[0010]
However, when the check code is completed with the data in the track in this way, there is a limit to the length of burst error that can be corrected. That is, even if an unrealistic 100% check code is added, the length of the burst error that can be corrected is limited to 1/2 track length. Therefore, in the case of adding a check code having a realistic redundancy, when a long burst error occurs, the residual error is unavoidable.
[0011]
Furthermore, in the above-mentioned apparatus, if the track width is narrowed to increase the recording density, the track deviation that occurs during editing is affected by variations in the mounting accuracy of the head mounted on the rotating drum and changes over time in the drum and tape. May cause burst errors. Therefore, in an apparatus that performs editing using a high-density recording tape, measures against burst errors are particularly important.
[0012]
[Problems to be solved by the invention]
This application has been made in view of the above points, and the problem to be solved is that when recording is performed by applying image compression, the conventional technique increases the data redundancy. The shortest recording wavelength is shortened, and the error rate of the original reproduction signal is deteriorated. Or there is a limit to the length of burst errors that can be corrected. Further, in an apparatus that performs editing using a high-density recording tape, measures against burst errors are particularly important.
[0013]
[Means for Solving the Problems]
The first means according to the present invention compresses digital data having correlation in time series, and forms an oblique track on the tape-like recording medium using the compressed digital data using a head mounted on a rotating drum. a method for formatting digital data recording medium to be used for and recorded, the processing for separating a plurality of pairs of said digital data to every other sample any number of the digital every the separated each set A process of dividing the data into a plurality of blocks every predetermined number, a process of compressing the digital data for each of the divided blocks, and combining the data of each compressed block with a predetermined outer code sequence In addition to generating a check code for error correction, the compressed block-by-block data and the generated check code can be corrected by the error correction. A process of binding a different sequence than the compressed each check code data and generated for each of blocks of the outer code sequence, different each which is the binding sequence and the separate each set And a process for recording on different tracks. The method of formatting a digital data recording medium, comprising:
[0014]
According to a second means of the present invention, in the method for formatting a digital data recording medium according to the first means, the signal recorded on the track is divided into each of the separated sets with respect to the minimum unit for editing the digital data. A method for formatting a digital data recording medium .
[0015]
According to a third means of the present invention, in the method for formatting a digital data recording medium according to the first means, the signal recorded on the track is divided into the separated sets with respect to the minimum unit for editing the digital data. And a method of formatting a digital data recording medium, including a process of circulating and recording one track at a time.
[0016]
[Action]
Therefore, according to the first means, the digital data is separated into a plurality of sets every arbitrary number of samples, and the digital data is divided into a plurality of blocks every predetermined number for each separated set. Digital data is compressed for each divided block, and the compressed block data is combined with a predetermined sequence of outer codes to generate a check code for error correction, and the compressed block data In addition, the generated check code is combined with data of each compressed block equal to or less than the number that can be corrected by error correction, and the generated check code is combined with a sequence different from the sequence of the outer code. By recording on a different track for each series and each separated set, even if all the digital data recorded on one track is lost, this check code is generated by the generated check code. Digital data dropped was able to reproduce, when compressing the digital data having the correlation with sequence, oblique tracks on a tape like recording medium by using a head mounted with the compressed digital data to the rotary drum Good recording can be carried out when forming the film.
[0017]
Further, according to the second means, the signal recorded on the track of the first means is recorded for each of the separated sets for the minimum unit of digital data editing. High recording is possible when error correction by interpolation is difficult.
[0018]
Further, according to the third means, the signal recorded on the track of the first means is recorded by circulating each separated set one track at a time for the minimum unit of digital data editing. If the error correction capability is low and error correction by interpolation is important, good recording can be performed.
[0019]
【Example】
The present invention compresses time-sequentially correlated digital data, and records the compressed digital data by forming an oblique track on a tape-shaped recording medium using a head mounted on a rotating drum. The present invention relates to a format method for a digital data recording medium used in the above.
[0020]
Therefore, also in the embodiment of the present invention, the digital data obtained by A / D-converting the video signal is separated into two sets of ◯ and ● every other sample as in the case shown in FIG. Each separated set is divided into, for example, blocks of 64 digital data of 8 × 8, for example, as shown by being surrounded by broken lines in FIG. 6, and compression is performed on the divided blocks. Is called.
[0021]
The compressed data obtained by compressing the data of one block in this way is arranged two-dimensionally as shown in FIG. 1B, and an outer code check code for error correction is generated for the outer code sequence, Similarly, an inner code check code for error correction is generated for the inner code series.
[0022]
Further, for the check code of the inner code block and the outer code, as indicated by the broken line in FIG. 1B, the check code of the inner code block and the outer code which are not more than the number correctable by the error correction described above. Each time, data is combined in a series (broken line) different from the above-described outer code series (thick line). Then, as shown in FIG. 1C, recording is performed so that a different track is formed for each of the combined different series.
[0023]
That is, for example, when four check codes of the inner code block are provided in the above-described check code of the outer code, error correction up to four inner code blocks can be performed. Therefore, in the recording medium formatting method described above, the inner code block and the outer code check code are separated, for example, every four, and these data are combined so as to traverse each outer code sequence.
[0024]
Further, FIG. 2 shows a configuration of a rotating drum, and for example, eight heads A to H are mounted on the rotating drum as shown in the figure. Then, the heads A to H are sequentially supplied with data combined so as to cross the above-described outer code series, for example, each of the combined series is obliquely applied to the tape-shaped recording medium. Recording is performed so that one track is formed.
[0025]
Thus, for example, when data of the minimum unit of editing (one field) is recorded in 8 tracks, recording is performed as shown in A or B of FIG. That is, A in FIG. 3 is a case where the data separated into the above-mentioned two sets of ○ and ● are recorded together for each set. FIG. 3B shows a case where the data separated into the above-mentioned two sets of ◯ and ● are recorded alternately (circulating) one track at a time.
[0026]
Therefore, in such a recording medium formatting method , if all of one track is missing, for example, the data surrounded by the broken line in FIG. 1B is not reproduced. However, in this case, when viewed from the above-described outer code series (thick line), only the four inner code blocks or outer code check codes are not reproduced in each outer code series. The check code of the outer code can be restored to the original data by the error correction described above.
[0027]
That is, in this recording medium formatting method , even when all data of one track is lost due to clogging of an arbitrary head or the like, this lost data is converted into original data by performing error correction on the reproduced data. Can be restored. As a result, even when all the data of one track is missing within the practical range of redundancy, the missing data can be restored to the original data.
[0028]
In practice, errors other than those due to clogging of the head may occur, so that the above-described check code of the outer code can correct the error of the check code of the inner code block and the outer code that are separated from each other. Somewhat more than the number. Further, the direction of another series (broken line) is not limited to the direction orthogonal to the outer code series (thick line) as shown in FIG.
[0029]
Thus, according to the above-described recording medium formatting method , the digital data is separated into a plurality of sets every arbitrary number of samples, and the digital data is divided into a plurality of blocks every predetermined number for each separated set. Then, the digital data is compressed for each of the divided blocks, and the compressed block data is combined with a predetermined sequence of outer codes to generate a check code for error correction, and the compressed block The data for each block and the generated check code are combined in a sequence different from the outer code sequence for each of the compressed block data and the generated check code that is less than the number that can be corrected by error correction. In addition, by recording each different series and each separated group on a different track, even if all the digital data recorded on one track is lost, it is generated. Check code by able to reproduce the digital data the missing was, when the digital data having the correlation compressed in sequence, a recording of the tape-shaped with a head mounted to the compressed digital data to the rotary drum Good recording can be performed when an oblique track is formed on the medium.
[0030]
Further, in the above-described recording medium formatting method , for example, when data of the minimum unit (1 field) of editing is recorded with 16 tracks, recording is performed as shown in A or B of FIG. That is, A in FIG. 4 is a case where the data separated into the above-described two sets of ○ and ● are recorded together for each set. FIG. 4B shows a case where the data separated into the above-mentioned two sets of ◯ and ● are recorded alternately (circulating) one track at a time.
[0031]
Therefore, in such a recording medium formatting method , first, in the recording medium formatting method of FIG. 4A, when all of one track is lost due to clogging of an arbitrary head or the like, A and B of FIG. As in the case of, the original data can be restored by error correction. However, in this case, if the cause of the omission is caused by a head such as clogging, the omission of the data separated into the above-described two sets of ○ and ● on average occurs.
[0032]
For this reason, there is no problem if the error is within the range of the correction capability. However, if the error exceeds the correction capability, an error will remain in the data separated into two sets of ○ and ●, and There is a risk that interpolation may not be performed. Therefore, this recording medium formatting method is effective for data that has a high error correction capability and is difficult to correct errors by interpolation.
[0033]
On the other hand, in the recording medium formatting method shown in FIG. 4B, when the cause of the omission is caused by a head such as clogging, the omission is concentrated on one of the data separated into two sets of ○ and ●. become. For this reason, the error correction capability of one set is reduced, but the other set is not affected. Therefore , the format method of the recording medium originally has a low error correction capability and emphasizes error correction by interpolation. Valid for data.
[0034]
Thus, according to the above-described recording medium formatting method , the signal recorded on each track described above is recorded together for each separated set with respect to the minimum unit of digital data editing. Therefore, good recording can be performed when error correction by interpolation is difficult.
[0035]
Alternatively, the signal recorded on each track described above is recorded by circulating each separated set one track at a time for the minimum unit of digital data editing, so that the error correction capability is relatively low, and errors caused by interpolation. Good recording can be performed when importance is attached to correction.
[0036]
Furthermore, in the above-mentioned apparatus, if the track width is narrowed to increase the recording density, the track deviation that occurs during editing is affected by variations in the mounting accuracy of the head mounted on the rotating drum and changes over time in the drum and tape. May cause burst errors.
[0037]
That is, when the track at the editing point is shifted forward, a part of the last track of the previously recorded track is erased as shown in FIG. 5A, and a burst error is added to the data from this last track. May occur. In the case of a shift later, a part of the previously recorded track remains as shown in FIG. 5B, and there is a possibility that a burst error may occur in the data of the first track at the editing point.
[0038]
By the way, in the format method of a digital data recording medium in which the minimum unit of editing is formed by a plurality of tracks and a check code for error correction is generated for each minimum unit of editing, for example, another series (broken line) described above is used. When the direction is set to a direction orthogonal to the outer code sequence (bold line) as shown in FIG. 1B, for example, the lowest sequence in the figure is used for error correction for each minimum unit of this editing. Only the check code of the outer code will be collected.
[0039]
Therefore, in this recording medium formatting method , a sequence in which only check codes of outer codes for error correction for each minimum unit of editing are collected is the final and / or first in the vicinity of the boundary for each minimum unit of editing. To be recorded on the tracks.
[0040]
Thus, in the above-described recording medium formatting method , for example, when recording is performed on a previously recorded tape by editing, a burst error occurs even if the track of the editing point is shifted back and forth as shown in FIG. This is only a check code of an outer code for error correction and has little influence on the original data. Therefore, even when error correction cannot be performed, residual error data can be kept to a minimum.
[0041]
Thus, according to the above-described recording medium formatting method , the error correction check codes are collected and recorded on the tracks near the boundary of each minimum unit of editing, so that a burst error due to track deviation at the time of editing can be prevented. Even if the error occurs, the error is concentrated on the check code and has little influence on the original digital data. Even in such a case, good recording can be performed.
[0042]
In the above-described embodiment, the example in which the digital data is separated into two sets of ○ and ● every other sample is described. However, even if the digital data is separated into three or more sets, each set is recorded on a separate track. By doing so, the same effect can be obtained.
[0043]
【The invention's effect】
According to the present invention, the digital data is separated into a plurality of sets every arbitrary number of samples, and the digital data is divided into a plurality of blocks for each of the separated sets by a predetermined number. Digital data is compressed for each block, and the compressed block-by-block data is combined with a predetermined sequence of outer codes to generate a check code for error correction. The check code is combined in a different sequence from the outer code sequence for each of the check block data and the number of compressed block codes that can be corrected by error correction. Even if all the digital data recorded on one track is missing by recording on different tracks for each separated set, this missing is caused by the generated check code. Can reproduce the digital data, compresses the digital data having the correlation time series, form tracks oblique to the tape-shaped recording medium using a head mounted with the compressed digital data to the rotary drum In this case, good recording can be performed.
[0044]
In addition, according to the present invention, the signal recorded on the above-mentioned track is recorded together for each separated set for the minimum unit of digital data editing. Good recording can be performed when correction is difficult.
[0045]
Furthermore, according to the present invention, the signal recorded on the above-described track is recorded by circulating each separated set one track at a time with respect to the minimum unit of digital data editing. Low, and good recording can be performed when error correction by interpolation is important.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining a method of formatting a digital data recording medium according to the present invention.
FIG. 2 is a configuration diagram of a rotating drum of a recording apparatus to which the present invention is applied.
FIG. 3 is an explanatory diagram when recording data of a minimum unit of editing with 8 tracks.
FIG. 4 is an explanatory diagram when recording data of a minimum unit of editing with 16 tracks.
FIG. 5 is an explanatory diagram of editing points.
FIG. 6 is a diagram for explaining when a video signal is separated into two sets;
FIG. 7 is a diagram for explaining a conventional method of formatting a digital data recording medium .
[Explanation of symbols]
A ~ H Head ●, ○ Pixel

Claims (3)

Digital used when compressing digital data with correlation in time series and recording the compressed digital data by forming an oblique track on a tape-shaped recording medium using a head mounted on a rotating drum A data recording medium formatting method comprising :
A process of separating the digital data into a plurality of sets every arbitrary number of samples;
A process of dividing the digital data into a plurality of blocks every predetermined number for each separated set;
A process of compressing the digital data for each of the divided blocks;
The compressed block-by-block data is combined with a predetermined outer code sequence to generate a check code for error correction,
The compressed block-by-block data and the generated check code can be corrected by the error correction, and the compressed block-by-block data and the generated check code are different from the outer code sequence. Processing to join in series,
A method for formatting a digital data recording medium, comprising: processing each of the combined different series and the recording on a different track for each of the separated sets. The digital data recording format according to claim 1, wherein
A method for formatting a digital data recording medium, comprising: a step of collectively recording signals recorded on the track for each of the separated sets with respect to a minimum unit for editing the digital data. The digital data recording format according to claim 1, wherein
A method for formatting a digital data recording medium, comprising: processing to circulate and record each of the separated sets one track at a time with respect to a minimum unit for editing the digital data. .

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