KR100207630B1 - Method for recording and reproducing of digital video tape with the enhanced error correcting capacity - Google Patents

Abstract

The present invention discloses a recording and reproducing method of a digital video tape having improved error correction capability.

The present invention is applied to an SD-VCR for recording and reproducing ATV signals. The present invention replaces trick play data with a predetermined number or predetermined pattern data to correct external error correction with normal play data, and reproduces play trick data. The external error correction decoding is performed by replacing the predetermined number or pattern data used in the external error correction encoding, thereby increasing the error correction rate for the normal playback data.

Description

Digital video tape recording method and playback method with improved error correction

1 is a diagram for explaining a video sector of a digital video tape having a recording format of an SD-VCR.

2 is a diagram for explaining an example of data arrangement for trick reproduction on a digital video tape.

3 is a diagram for explaining another example of data arrangement for trick reproduction on a digital video tape.

4 is a block diagram according to an embodiment of a digital video tape recording apparatus according to the present invention.

5A and 5B are diagrams for explaining external and internal error correcting codes respectively performed in the error correcting code unit shown in FIG. 4 for data arrangement shown in FIG.

6A and 6B are diagrams for explaining the external and internal error correcting codes performed in the error correcting code unit shown in FIG. 4 for data arrangement shown in FIG.

7A and 7B are diagrams for explaining the trick-play data area shown in FIGS. 5B and 6B.

FIG. 8 is a diagram for explaining the interleaving order performed in the ECC block rearrangement unit shown in FIG.

FIG. 9 is an internal block diagram of the ECC block rearrangement unit shown in FIG.

10, 11 and 12 are diagrams for explaining the recording format of a digital video tape according to the present invention.

13 is a block diagram according to an embodiment of a digital video tape reproducing apparatus according to the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital video tape recording method and a reproducing method. In particular, in a digital video tape recording and reproducing apparatus for recording and reproducing an ATV (Advanced Television) signal, recording and reproducing video data with improved error correction capability during normal playback. It is about a method.

The development of consumer digital video cassette players (hereinafter referred to as DVCRs) for recording and reproducing ATV signals on digital video tapes is in progress.

In particular, in the SD (Standard Definition) -VCR for recording and reproducing ATV signals, research on a recording format for special reproduction that satisfies image quality and cost has continued. When the ATV signal is transmitted to the SD-VCR through a cable, it is transmitted as a transport packet having an MPEG-2 structure proposed by the Moving Picture Experts Group (MPEG).

On the other hand, the SD-VCR signal is intra frame coded data and has an ECC (Error Correction Code) structure. In ECC, the code in the column direction is called the inner code (85,8) and the code in the row direction is called the outer code (149,11).

When writing, external error correction code is performed by adding 11 bytes of external additional information to 138 bytes of external code in the row direction, and 8 bytes of internal additional information is added to 77 bytes of internal code in the column direction to correct internal errors. Encode

During playback, after correcting up to 4 bytes out of 85 bytes, the sync block that has not been corrected is sent with an error flag, and then sent through an error correction decoding process.In case of external error correction decoding, this error flag is used to select up to 11 out of 149 bytes. Correct to byte.

In the SD-VCR signal, one frame is segmented into five segments, one macroblock is collected from each segment, and arranged in predetermined positions of the track in units of five macroblocks. Since the bit amount is fixed, trick play was possible.

On the other hand, the ATV signal has an MPEG-2 structure and is inter frame coded, and a video sector on a tape having an SD-VCR recording format has a normal playback data area and tricks for normal playback data and trick playback data. There is a separate data area for playback.

Here, since interframe coding encodes the difference between adjacent frames in one frame (up to 15 frames), except for an intra frame, when an error occurs in one frame, an error occurs in almost all frames in the corresponding GOP. .

Therefore, in the SD-VCR recording and reproducing the ATV signal, since the ATV signal is inter-frame coded, there is a problem that it is fatally damaged when an error occurs in the normal reproduction data of the ATV signal.

In order to solve this problem, conventionally, the ECC3 area for error correction of normal playback data is added to the ECC1 area, which is an external additional information area added to an external code, and the ECC2 area, which is an internal additional information area added to an internal code. There is a problem that the recording efficiency of pure normal playback data is lowered because it is allocated separately to a predetermined position in the playback data area.

SUMMARY OF THE INVENTION An object of the present invention is to provide a digital video tape recording method and a reproducing method for increasing error correction rate for normal reproduction data without a separate ECC3 region during normal reproduction in an SD-VCR for recording and reproducing ATV signals.

Another object of the present invention is to correct an error of normal playback data during normal playback by setting and encoding a predetermined integer or constant pattern data in a trick play data area during external error correction coding in SD-VCR for recording and playing ATV signals. There is provided a digital video tape recording and reproducing method for increasing the rate.

It is still another object of the present invention to set and encode a predetermined constant or constant pattern data in a trick data area for external error correction coding in SD-VCR for recording and reproducing ATV signals, and then interleaving them in track units to perform burst errors ( The present invention provides a digital video tape recording method and a reproducing method of increasing the error correction rate by randomizing a burst error.

In order to achieve the above objects, the digital video tape recording method according to the present invention divides an ATV signal including frame data, which is supplied at predetermined intervals and independently decodable, into normal video data and trick playback data, and then to digital video tape. A method of recording;

Separating normal play data and trick play data from the transmitted ATV signal, wherein the trick play data is extracted from frame data;

Replacing the trick play data with a predetermined pattern data and encoding an external error correcting code together with the normal play data;

Internal error correcting encoding for each of the external error correcting coded normal reproduction data and the extracted trick reproduction data; And

And a recording step of modulating the internal error correcting coded normal playback data and trick playback data to record at a predetermined position of each track on the tape.

A digital video tape reproducing method according to the present invention comprises the steps of: reproducing and demodulating normal reproduction data and trick reproduction data recorded in a video sector on a digital video tape;

Internal error correction decoding of the reproduced normal reproduction data and the trick reproduction data, respectively;

Replacing the internal error correction decoded trick reproduction data with a predetermined pattern data to perform external error correction decoding on the normal reproduction data; And

And outputting an ATV signal by combining the external error correction decoded normal reproduction data and the internal error correction decoded trick reproduction data.

Hereinafter, with reference to the accompanying drawings will be described a preferred embodiment of the digital video tape recording method and playback method with improved error correction capability according to the present invention.

1 shows a structure of a data sync block (hereinafter referred to as an ECC block structure) of a video sector of a digital video tape having a recording format of SD (Standard Definition) -VCR.

The video sector is composed of a video preamble (not shown), a 149 data sync block, and a video postamble (not shown). The video preamble starts with 400 bits of run-up (after modulation) and ends with two pre-sync blocks. The video postamble starts with a post sync block and ends with a 925-bit guard area (after modulation).

On the other hand, a problem in the development of DVCR has been to take the method of having the ECC block structure shown in Figs. 2 or 3 in order to realize a recording format for special reproduction that can satisfy both image quality and cost.

The ECC block structure shown in FIG. 2 is applied to a tape having a recording format for repeatedly recording trick-playing data on tracks corresponding to twice the maximum speed. Place it in place.

The ECC blocks shown in FIG. 2 include 19-20 sync blocks as the first video auxiliary data area, 21-126 sync blocks as the normal play data area, 127-156 sink blocks as the trick play data area, It consists of 156 sink blocks, which are video auxiliary data areas, and 157-167 sink blocks, which are external information fields.

Each sync block consists of 2 bytes of sync code, 3 bytes of identification code, 77 bytes of data, and 8 bytes of internal code for error correction.

Since this method only needs to scan in the repetitive recording area, it does not require accurate servo control, so there is no problem of cost increase, but there is a problem of consuming a large recording area by repetitive recording, and freezing one screen at low speed compared to high speed. There is a problem that the freezing time becomes long and boring, and when the image quality is poor, it is annoying.

The ECC block structure shown in Fig. 3 is applied to a tape having a recording format for arranging trick-playing data in a scan area corresponding to each double speed, and the trick-playing data areas are distributedly arranged in k forms. Where M, N, m, k0

In the ECC block structure shown in FIG. 3, the N-20 sink blocks, the first through the first to the k < th > The m normal reproduction data area is made up of M (105) byte sync blocks, 156 sink blocks as the second auxiliary data area, and 157-167 sink blocks as the external additional information area.

This method has a good picture quality of the trick-playing playback screen, but the cost must be increased due to the burden of accurate servo control because the corresponding arrangement area must be scanned.

The present invention proposes a method of increasing the error correction rate for normal playback data when the data recorded on the tape having the ECC block structure shown in FIG. 2 or 3 is normally played back.

Next, an Example is described.

4 is a block diagram according to an embodiment of a digital video tape recording apparatus according to the present invention.

Referring to FIG. 4, the video signal input to the preprocessor 10 is an ATV signal, and the ATV signal is an inter-frame coded signal and has an MPEG-2 transmission packet structure.

The preprocessor 10 separates and transmits only the video layer from the MPEG-2 transport packet.

The MPEG-2 signal input to the SD-VCR recording and reproducing the ATV signal has a transmission packet structure composed of a system layer. The system layer includes side information (user data), video data, and audio data. It is composed. Here, the video data has a structure of MPEG-2.

In addition, since the SD-VCR has a trick play function, the trick play data extracted from the transferred MPEG-2 video data is also composed of the MPEG-2 video data structure and the MPEG-2 transport packet. And be recorded on a digital videotape.

The normal / trick play data separator 20 separates normal play data and trick play data from the MPEG-2 video data output from the preprocessor 10.

The ATV signal input to the SD-VCR is data encoded between frames in units of 1 GOP as described above.

In general, a signal composed of these data types can be coded independently using intra frame data (I) that can be independently coded without any other picture data, and can be coded using motion compensation from preceding intra frame data or predicated frame data. Frame data (P), and bidirectional predicted frame data (B) that can be coded using motion compensation from preceding intra frame data or predicted frame data and subsequent intra frame data or predicted frame data. do.

One embodiment of the display reproduction order of the ATV signal specified in MPEG-2 is I-B-B-P-B-B-P-B-B-P-B-B-P-I --- and the order of the transmission bit sequences is I-P-B-B-P-B-B-P-B-B-P-B-B-I ---.

Therefore, the data for trick reproduction is selected and used independently of the intra frame data which can be coded. Among intra frames, only a few coefficients per block (typically one DC coefficient and 1-2 AC coefficients per block) are taken and transmitted in an MPEG-2 structure.

The trick play data recorded in the video sector is used by selecting intra frame data.

In order to obtain trick play data from the video data configured in this form, data from an intra frame is usually extracted to reduce hardware complexity.

The mixing unit 30 mixes the sync code and the identification code with the normal reproduction and trick reproduction data output from the normal / trick reproduction data separation unit 20.

In error correction encoding 40, error correction encoding is performed on the data output from the mixing unit 30. The code used for error correction coding is a two-dimensional Reed-Solomon code (R-S Code).

The external error correction coder 41 of the error correction coder 40 adds 11 bytes of external additional information to the 138-byte sync block, where N of the trick-play data area is 30 in the 138-byte sync block. ) Set all sink block data to 0 to perform external error correction coding.

In the case of arranging trick-play data as shown in Fig. 2, as shown in Fig. 5A, it is set to 0 in the trick-play data area and external information is added.

When the trick-play data is arranged as shown in Fig. 3, as shown in Fig. 6A, all of the first to k-th trick-play data areas are set to 0 and external additional information is added.

In the present invention, a predetermined number other than 0 can be set in the trick-play data area composed of N sync blocks, or N-byte constant pattern data (numbers) are placed in the row direction or 77-byte constant pattern data in the longitudinal direction. External error correction can also be done.

In the internal error correction coder 42 of the error correction coder 40, when the track reproduction data is arranged as shown in FIG. 2, as shown in FIG. 8 bytes of internal additional information is added to the data.

In the case of arranging trick-playing data as shown in FIG. 3, as shown in FIG. 6B, 8 bytes of internal additional information is added to 77 bytes of data as in the conventional method.

Therefore, in the internal error correcting encoding, internal additional information is added to normal playback data and trick playback data.

At this time, only trick-play data is recorded in the trick-play data area shown in FIGS. 5B and 6B as shown in FIG. 7A or external for error correction of trick-play data and trick-play data as shown in FIG. 7B. Additional information is recorded.

In the trick play mode, only the data in the trick play data area used for internal error correction encoding is used without using the external additional information (11 bytes).

Therefore, when the external error correction code is encoded by replacing the data of the trick reproducing data area of the N-sink block with a predetermined number or data of a predetermined pattern (number), 11 to (138-N) bytes during normal reproduction are encoded. This has the effect of adding additional information of bytes.

That is, when correcting the external error correction and decoding during normal playback, error correction was possible up to 11 bytes for 149 (138 + 11) bytes. However, in the present invention, M + 11 except for trick play data (here 138-30 + 11) = 11) By 11 bytes can be corrected for bytes, the error correction rate can be increased without major hardware change.

The ECC block rearrangement unit 50 interleaves the error correction coded data. In-track interleaving is performed on blocks that do not exist in the conventional SD-VCR, so that errors can be actively coped with.

In the present invention, interleaving is performed as shown in FIG. The data is rearranged diagonally so that the data in each sync block does not overlap each other.

That is, after reading the internal error correction coded data in the direction indicated by 1, in the order of data D ₀ , ₀ , D ₁ , ₁ , D ₂ , ₂ , D ₃ , ₃ , ..., D ₈₄ , ₈₄ , Read data D ₈₅ , ₀ , D ₈₆ , ₁ , ..., D ₁₁₈ , ₃₃ in the direction indicated by 1 ′.

Next, the data D ₀ , ₁ , D ₁ , ₂ , ..., D ₈₅ , ₈₄ are read in the direction indicated by 2, and then data D ₈₄ , ₀ , D ₈₅ , ₁ , in the direction indicated by 2 '. Read in the order ..., D ₁₁₈ , ₃₄ . In this order, data D ₀ , ₈₄ is read in the direction indicated by 85, and data D ₁ , ₀ , D ₂ , ₁ , ..., D ₈₅ , ₈₄ is read in the direction indicated by 85 ', Finally, data are read in the order indicated by 85 in the order of data D ₈₆ , ₀ , D ₈₇ , ₁ , ..., D ₁₁₈ , ₃₂ .

An internal block diagram of the ECC block rearrangement unit 50 is shown in FIG.

The first memory 51 and the second memory 52 toggle each other to read or write data, and the control signal generator 55 writes / reads the address addr1 and the second memory of the first memory 51. The write / read address addr2 and the write / read control signal R / W of 52 are outputted.

That is, when the write / read control signal R / W is high in the control signal generator 55, the data stored in the first memory 51 is read in the interleaved order shown in FIG. Is transmitted to the modulator 60 shown in FIG. 4, and the second memory 52 is output from the internal error correction coder 42 shown in FIG. 4 through the demultiplexer 53. (105 normal playback sync block + 3 video auxiliary sync block) data is written.

When the write / read control signal R / W is low in the control signal generator 55, the first memory 51 outputs 108 sink block data output from the internal error correcting encoder 42 through the demultiplexer 53. Are sequentially written, and the data stored in the second memory 52 is read out in the interleaved order shown in FIG. 8 and transmitted to the modulator 60 through the multiplexer 54.

The write addresses generated by the control signal generator 55 are sequential addresses in the order of D ₀ , ₀ , D ₀ , ₁ , D ₀ , ₂ , ..., D ₁₁₈ , ₈₄ , but the read addresses are shown in FIG. D ₀ , ₀ , D ₁ , ₁ , D ₂ , ₂ , D ₃ , ₃ , ..., D in the directions 1,1 ', 2,2', ..., 85,85 ', 85 ₈₄ , ₈₄ , D ₈₅ , ₀ , D ₈₆ , ₁ , ..., D ₁₁₈ , ₃₃ , D ₀ , ₁ , D ₁ , ₂ , ..., D ₁₁₈ , ₃₂ .

As shown in FIG. 8, the interleaved data is modulated by the modulator 60 and recorded on the tape, and the tape format is as shown in FIG. 10, 11, and 12. FIG.

FIG. 10 shows a tape having a format for repeatedly recording trick-play data recorded in a pair of tracks in tracks corresponding to twice the maximum speed.

Each track shown in FIG. 10 is composed of an audio sync block, a pre sync block, a trick play sync block in which trick play data is recorded, a normal play sync block in which interleaved data is recorded, and a post sync block.

11 shows a tape having a recording format for placing trick-play data in a scan area corresponding to each double speed.

Each track shown in FIG. 11 includes an audio sync block, a free sync block, a trick play sync block divided into a predetermined number (k), a normal play sync block divided into a predetermined number (m) in which interleaved data is recorded, and a post. It is a sink block.

FIG. 12 shows an example in which the recording formats shown in FIGS. 10 and 11 are alternately recorded in two track periods. FIG. 12 is a format for compensating the disadvantages of poor image quality of the recording format shown in FIG. 10 and the cost increase of the recording format shown in FIG.

Therefore, when burst interleaved data is recorded in the recording formats shown in FIGS. 10, 11, and 12, the interleaved data on the normal reproducing sink block is treated as a random error to actively deal with burst errors. It can respond.

13 is a block diagram of an embodiment of a digital video tape data reproducing apparatus according to the present invention.

The playback device shown in FIG. 13 plays back data from a digital video tape in the reverse order of the recording device shown in FIG.

The demodulator 110 demodulates the data reproduced from the tape.

The inverse ECC block rearrangement unit 120 deinterleaves the demodulated video data in the data order of the original ECC block structure.

The error correction decoding unit 130 performs error correction decoding on the deinterleaved data.

That is, the internal error correction decoding unit 131 of the error correction decoding unit 130 corrects an error to 4 bytes for a 77-byte sync block, and then attaches an error flag to a sync block outside the error correction capability.

Since the error correction code uses two-dimensional Reed Solomon code, the internal error correction capability is (internal information / 2) bytes.

In the error correction decoding unit 130, the external error correction decoding unit 132 sets 0 or other numbers used in the external error correction code or N-byte pattern data (number) in the row direction in the trick play data area. Decrypt external error correction. In this way, errors can be corrected up to 11 bytes for M (105) byte sync blocks.

The separation unit 140 separates the sync code and the identification code from the error correction decoding normal reproduction and trick reproduction data output from the error correction decoding unit 130.

The normal / trick play data combination unit 150 inputs the normal play and trick play data from which the sync code and the identification code separated from the separating unit 140 are input, and according to the normal play mode or the trick play mode, the normal play data and the trick play mode. The reproduction data is combined again, and the combined normal reproduction and trick reproduction data are converted into transmission packets by the inversion processing unit 160 to output the ATV signal.

As described above, in the SD-VCR for recording and reproducing ATV signals, the trick-play data is replaced with predetermined integer data or predetermined pattern data, and external error correction coded together with the normal playback data to normalize normal playback. There is an effect of increasing the error correction rate for the reproduction data.

In addition, the present invention has the effect of increasing the error correction rate by randomizing the burst error by replacing the trick play data with a predetermined integer data or a predetermined pattern data and encoding an external error correction code together with the normal play data and then interleaving. .

Claims (18)

A method for recording an ATV signal including frame data which is supplied at predetermined intervals and independently decodable, is divided into normal playback data and trick playback data and recorded on a digital video tape; Separating normal play data and trick play data from the transmitted ATV signal, wherein the trick play data is extracted from frame data; Replacing the trick play data with a predetermined pattern data and encoding an external error correcting code together with the normal play data; Internal error correcting encoding for each of the external error correcting coded normal reproduction data and the extracted trick reproduction data; And a recording step of modulating the internal error correcting normal reproduction data and trick reproduction data to record at a predetermined position of each track on the tape. The digital video tape recording method as claimed in claim 1, wherein the predetermined pattern data is predetermined integer data. 2. The digital video tape recording method as claimed in claim 1, wherein the predetermined pattern data is a number having the same pattern in the row direction with respect to the trick play sync block. The digital video tape recording method as claimed in claim 1, wherein the predetermined pattern data is a number having the same pattern in the longitudinal direction with respect to the trick play sync block. The method of claim 1, further comprising: interleaving the internal error correcting normal reproduction data in a diagonal direction and transmitting the data to the recording step so that data in one sync block does not overlap each other in a track unit. Digital video tape recording method characterized by. 2. The digital video tape recording method as claimed in claim 1, wherein in the recording step, track reproduction data is repeatedly recorded at predetermined positions of tracks corresponding to twice the maximum speed. 2. The digital video tape recording method as claimed in claim 1, wherein in the recording step, trick-play data is recorded in a scan area corresponding to each double speed. 2. The trick reproducing data according to claim 1, wherein in the recording step, trick-play data is repeatedly recorded at predetermined positions of tracks corresponding to a double speed of the maximum speed alternately at predetermined track periods, or the scan area corresponding to the scan area corresponding to each double speed. Digital video tape recording method, characterized in that for recording. Reproducing and demodulating normal reproduction data and trick reproduction data recorded in a video sector on a digital video tape; Internal error correction decoding of the reproduced normal reproduction data and the trick reproduction data, respectively; Replacing the internal error correction decoded trick reproduction data with a predetermined pattern data to perform external error correction decoding on the normal reproduction data; And outputting an ATV signal by combining the external error correction decoded normal reproduction data and the internal error correction decoded trick reproduction data. 10. The method of claim 9, wherein the predetermined pattern data is predetermined integer data. 10. The method of claim 9, wherein the predetermined pattern data is a number having the same pattern in the row direction with respect to the trick play sync block. 10. The method of claim 9, wherein the predetermined pattern data is a number having the same pattern in the longitudinal direction with respect to the trick play sync block. 10. The method of claim 9, further comprising: deinterleaving the reproduced normal reproduction data into an original error correction code block structure and transmitting the decoded data to the internal error correction decoding step. A method for recording and reproducing an ATV signal including frame data supplied at predetermined intervals and independently decodable into normal playback data and trick playback data on a digital video tape; Separating normal play data and trick play data from the transmitted ATV signal, wherein the trick play data is extracted from frame data; Replacing the trick reproduction data with a predetermined number and performing external error correcting encoding together with the normal reproduction data; Internal error correcting encoding for each of the external error correcting coded normal reproduction data and the extracted trick reproduction data; Interleaving the internal error correcting coded normal playback data and recording the interleaved normal playback data and the internal error correcting coded trick playback data on the digital video tape; Reproducing normal reproduction data and trick reproduction data from the digital video tape to deinterleave the normal reproduction data; Internal error correction decoding of the trick reproduction data and the deinterleaved normal reproduction data, respectively; Replacing the internal error correction decoded trick-play data with a predetermined number to perform external error correction-decode on normal playback data; And outputting an ATV signal by combining the external error correction-decoded normal reproduction data and the internal error correction-encoded trick reproduction data. 15. The digital video tape recording and reproducing method according to claim 14, wherein in the external error correcting encoding step, the external error correcting encoding is performed by replacing trick playback data with a predetermined pattern data in a row direction. 15. The digital video tape recording and reproducing method according to claim 14, wherein in the external error correcting encoding step, the external error correcting encoding is performed by replacing trick playback data with a predetermined pattern data in the longitudinal direction. 16. The digital video tape recording and reproducing method according to claim 15, wherein in the external error correcting decoding step, external error correction decoding is performed on normal playback data by replacing the trick playback data with a predetermined pattern data in a row direction. The digital video tape recording and reproducing method according to claim 16, wherein the external error correction decoding step replaces the trick reproduction data with a predetermined pattern data in the longitudinal direction and performs external error correction decoding on normal reproduction data.