JP2001283532A - Magnetic tape recorder and method for magnetic tape recording, format of magnetic tape, and recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the error tolerance of subcode data. SOLUTION: On each track of a magnetic tape which is formed obliquely along the length, a main sector and a subcode sector are formed continuously without leaving any gap between them. In the subcode sector, 10 subcode sync blocks are formed and to each sync block, 2-byte (16 bits) sync, 3-byte (24 bits) ID, 5-byte (40 bits) subcode data, and 5-byte (40 bits) parity are added. A Reed- Solomon code is composed of the ID, subcode data, and parity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic tape recording apparatus and method, a magnetic tape format, and a recording medium, and more particularly, to a magnetic tape recording system capable of recording or reproducing high-quality video data on a magnetic tape. The present invention relates to an apparatus and a method, a format of a magnetic tape, and a recording medium.

[0002]

2. Description of the Related Art Recently, compression techniques have been advanced, and video data and the like have been compressed by, for example, the DV (Digital Video) system and recorded on a magnetic tape. A format for this is defined as the DV format of a consumer digital video tape recorder.

FIG. 1 shows the structure of one track in the conventional DV format. In the DV format, the video data is recorded after being converted into 24-25. However, the bit number of the numeral shown in FIG. 1 represents the numerical value after the 24-25 conversion.

The range corresponding to the 174-degree winding angle of the magnetic tape is substantially the range of one track. Outside the range of one track, an overwrite margin having a length of 1250 bits is formed. This overwrite margin is for eliminating the remaining unerased data.

The length of one track range is 60 × 100.
When the rotating head is rotated in synchronization with the frequency of 0/1001 Hz, the number of bits is 134975 bits. When the rotating head is rotated in synchronization with the frequency of 60 Hz, 134850 bits are used.
Bit.

In this one track, an ITI sector, an audio sector, a video sector, and a subcode sector are sequentially arranged in the trace direction of the rotary head (from left to right in FIG. 1). , A gap G1 is formed between the audio sector and the video sector, and a gap G3 is formed between the video sector and the subcode sector.

An ITI (Insert and Track Information) sector has a length of 3600 bits, and a 1400-bit preamble for generating a clock is arranged at the head thereof, followed by an SSA (Start Sync Area) and a TIA. (Tra
ck Information Area) is provided for a length of 1920 bits. In the SSA, a bit string (sync number) necessary for detecting the position of the TIA is arranged. In the TIA, information indicating a consumer DV format, information indicating an SP mode or an LP mode, information indicating a pattern of a pilot signal of one frame, and the like are recorded. Following the TIA, a 280-bit postamble is arranged.

[0008] The length of the gap G1 is 625 bits.

The audio sector has a length of 11550 bits. The first 400 bits and the last 500 bits are respectively a preamble or a postamble, and the 10650 bits between them are data (audio data).

The gap G2 has a length of 700 bits.

The video sector has 11225 bits, and the first 400 bits and the last 925 bits of the video sector are
Each is a preamble or a postamble, and 111900 bits between them are used as data (video data).

The length of the gap G3 is 1550 bits.

The sub-code sector has a rotating head of 60 ×
When rotated at a frequency of 1000/1001 Hz, 37
When it is 25 bits and rotated at a frequency of 60 Hz, 3
It is set to 600 bits. The first 1200 bits are preamble and the last 1325 bits (when the rotating head is rotated at a frequency of 60 × 1000/1001 Hz) or 1200 bits (when the rotating head is 6 bits).
Rotation at a frequency of 0 Hz).
00 bits are used as data (subcode).

The 1200-bit data section of the subcode sector shown in FIG. 1 is composed of 12 sync blocks each having a length of 100 bits.

FIG. 2 shows the structure of a sync block in a subcode sector before 24-25 conversion. The total length is 12 bytes (= 96 bits), a 2-byte sync pattern is arranged at the beginning, and a 3-byte ID is arranged next. Next to the ID, 5-byte main data (subcode data) is arranged. Next to the main data, a 2-byte parity (C1) is arranged.

The 3-byte ID includes (12,8,3) BCH
An error correction code is added in a two-sided configuration of the code.

Further, the (14, 10, 5) Reed-Solomon code of the Galois field GF (2 ⁴ ) is constituted by the 5-byte main data and the 2-byte parity C1 as an error correction code.

[0018]

However, since the ID of the DV format has a minimum Hamming distance of 3 symbols, an error of a distance of 3 symbols may be corrected to another code. Further, since the BCH code is a binary code, if the bit strings are arranged in the order of NG-OK-NG, there is a possibility that the BCH code may be erroneously corrected.

Further, in the case of the DV format, GF
Since the (14, 10, 5) Reed-Solomon code of (2 ⁴ ) is used, there is a problem that the robustness against errors is not sufficient.

The present invention has been made in view of such a situation, and is intended to suppress erroneous correction and improve the tolerance against errors.

[0021]

A magnetic tape recording apparatus according to the present invention comprises a first group of data including video data, audio data or search data, and a second group of data including subcode data related to the first group of data. A formatting means for adding an error correcting code to each of the data of the groups, and formatting the data so that the two are continuous on the track of the magnetic tape without being separated from each other, and the formatting means. Supply means for supplying the formatted data to a rotary head for recording on a magnetic tape, wherein the formatting means comprises one 15-byte long track for each of the second group of data. Multiple sync blocks are continuously arranged, and two sync block detection patterns are provided in one sync block. DOO, 3 bytes identification information for identifying the sync block, 5-byte main data,
5 bytes of identification information and parity for main data are arranged, and (13, ^{8, 6} ) of the Galois field GF (2 ⁸ ) is determined by the identification information, main data, and parity.
It is characterized by constituting a Reed-Solomon code or a (13,8,6) Reed-Solomon code of Galois field GF (2 ⁴ ) having a two-sided configuration.

The formatting means may arrange ten sync blocks continuously on one track.

According to the magnetic tape recording method of the present invention, a first group of data including video data, audio data or search data, and a second group of data including subcode data related to the first group of data are provided. Are respectively formatted by the processing of a formatting step of formatting the magnetic tape tracks so that they are continuous without being separated from each other, and a formatting step. Supplying the formatted data to a rotary head for recording on a magnetic tape, wherein the formatting step includes one 15 byte long track on each track for the second group of data. Multiple sync blocks are successively arranged, and one sync block is used for sync block detection. The detection pattern is 2 bytes, the identification information for identifying the sync block is 3 bytes, the main data is 5 bytes, and the parity for the identification information and the main data is 5 bytes, and the Galois is determined by the identification information, the main data, and the parity. Field GF (2 ⁸ )
(13,8,6) Reed-Solomon code or Galois field GF (2 ⁴ ) (13,8,6) Reed-Solomon code having a two-sided configuration.

[0024] The program of the recording medium of the present invention comprises a first group of data including video data, audio data or search data, and a second group of data including subcode data related to the first group of data. A formatting step of adding an error correcting code to each of them, and formatting each of them on a track of a magnetic tape so that the two are continuous without being separated from each other;
Supplying the data formatted by the processing of the formatting step to the rotary head for recording on the magnetic tape, wherein the processing of the formatting step includes the steps of: In addition, a plurality of sync blocks each having a length of 15 bytes are continuously arranged, and one sync block has a detection pattern for detecting a sync block of 2 bytes and identification information for identifying the sync block. 3 bytes, 5 bytes of main data, and 5 bytes of identification information and a parity for the main data are arranged, and the Galois field GF (2 ⁸ ) is determined by the identification information, the main data, and the parity.
(13,8,6) Reed-Solomon code or Galois field GF (2 ⁴ ) (13,8,6) Reed-Solomon code having a two-sided configuration.

The format of the magnetic tape according to the present invention includes a first group of data including video data, audio data or search data, and a second group of data including subcode data related to the first group of data. Are added to each of them with an error correcting code. Each of them is formatted so as to be continuous on the track without being separated from each other. A plurality of sync blocks each having a length of 15 bytes are continuously arranged, and one sync block has a detection pattern for detecting a sync block of 2 bytes and identification information for identifying a sync block of 3 bytes. Byte, main data of 5 bytes, and identification information and a parity for the main data of 5 bytes are arranged. Data, and by parity,
Galois field GF (2 ⁸ ) (13,8,6) Reed-Solomon code or two-sided Galois field GF
It is characterized in that the (13, 8, 6) Reed-Solomon code of (2 ⁴ ) is configured.

The magnetic tape recording apparatus and method of the present invention,
In the format of the magnetic tape and the program of the recording medium, the sync block of the data of the second group has a length of 15 bytes.
The (13,8,6) Reed-Solomon code of the Galois field GF (2 ⁸ ) or the Galois field GF having a two-sided configuration is used according to the identification information, the main data, and the parity.
The (13, 8, 6) Reed-Solomon code of (2 ⁴ ) is configured.

[0027]

FIG. 3 shows a configuration example of a recording system of a magnetic tape recording / reproducing apparatus to which the present invention is applied. The video data compression unit 1 compresses the input HD video signal using an MPEG method such as MP @ HL or MP @ H-14. The audio data compression unit 2 compresses the audio signal corresponding to the HD video signal by, for example, a method corresponding to a DV format audio compression method. System data including AUX (auxiliary) data and subcode data is input from the controller 13 to the terminal 3.

The switch 4 is switched by the controller 13 to appropriately select the output of the video data compression unit 1, the output of the audio data compression unit 2, or the system data supplied from the terminal 3 at a predetermined timing, and to select an error code. The ID is supplied to the ID adding unit 5. The error code ID adding unit 5 adds an error detection correction code or ID to the input data, performs an interleaving process between 16 tracks, and outputs the data to the 24-25 conversion unit 6. The 24-25 converter 6 converts the input 24-bit data into 25-bit data by adding redundant one bit selected so that the component of the tracking pilot signal is strong. I do.

The sync generator 7 generates sync data to be added to main data (FIG. 10) or subcode (FIG. 11), which will be described later, and amble data.

The switch 8 is controlled by the controller 13 to control the output of the 24-25 converter 6 or the sync generator 7
Is selected and output to the modulation unit 9. Modulation unit 9
Is a method suitable for recording data input via the switch 8 in order to prevent consecutive ones or zeros and recording the data on the magnetic tape 21 (the same method as in the DV format). And supplies it to the parallel / serial (P / S) converter 10.

The parallel-to-serial converter 10 converts the input data from parallel data to serial data. The amplifier 11 amplifies the data input from the parallel-to-serial conversion unit 10, attaches it to a rotating drum (not shown), supplies the data to the rotating head 12 that is rotated, and records the data on the magnetic tape 21.

FIG. 4 shows that the rotary head 1 is attached to the magnetic tape 21.
2 shows the format of the track formed. The rotating head 12 traces the magnetic tape 21 from the lower right in the figure to the upper left, thereby forming a track inclined with respect to the longitudinal direction of the magnetic tape 21. The magnetic tape 21 is transported from right to left in the drawing.

Each track has an F signal according to the type of a pilot signal recorded therein for tracking control.
0, F1, or F2. Truck is F
0, F1, F0, F2, F0, F1, F0, F2.

As shown in FIG. 5, neither pilot signals of frequencies f1 and f2 are recorded on the track F0. On the other hand, as shown in FIG. 6, a pilot signal having a frequency f1 is recorded on the track F1.
As shown in FIG. 7, a pilot signal of frequency f2 is recorded on track F2.

The frequencies f1 and f2 are 1/90 or 1/60 of the recording frequency of the channel bit, respectively.

As shown in FIG. 5, the depth of the notch at the frequencies f1 and f2 of the track F0 is 9 dB. On the other hand, as shown in FIG. 6 or FIG. 7, the CNR of the pilot signal of frequency f1 or f2 (Car
rier to Noise Ratio) is greater than 16dB and 19dB
It is set to a smaller value. The depths of the notches at the frequencies f1 and f2 are set to values larger than 3 dB.

The track pattern having this frequency characteristic is the same as the DV format.
Therefore, the magnetic tape, rotating head, drive system, demodulation system, and control system of the consumer digital video tape recorder can be used as they are in this embodiment.

The track pitch and the tape speed are the same as those in the DV format.

FIG. 8 shows an example of the sector arrangement of each track. In FIG. 8, the number of bits of the length of each part is represented by the length after the 24-25 conversion. The length of one track is such that the rotating head 12 is 60 × 1000/10
When rotated at a frequency of 01 Hz, it becomes 134975 bits, and when rotated at a frequency of 60 Hz, 13485 bits are used.
It is set to 0 bit. The length of one track is a length corresponding to a 174-degree winding angle of the magnetic tape 21, and an overwrite margin of 1250 bits is formed behind it. This overwrite margin is for preventing unerased portions.

In FIG. 8, the rotating head 12 traces a track from left to right. At the beginning, 18
A 00-bit preamble is arranged. This preamble needs to generate a clock, for example,
Data shown in pattern A and pattern B as shown in FIG. 9 are recorded in combination. Pattern A and Pattern B
Is a pattern in which the values of 0 and 1 are reversed. By appropriately combining these patterns, the tracking patterns of the tracks F0, F1, and F2 shown in FIGS. 5 to 7 can be realized. Note that the run pattern in FIG. 9 represents the pattern after the 24-25 conversion by the 24-25 conversion unit 6 in FIG.

After the 1800-bit preamble,
A main sector having a length of 130425 bits is arranged. The structure of this main sector is shown in FIG.

As shown in the figure, the main sector is 141
Each sync block has a length of 888 bits (111 bytes).

The first 123 sync blocks are 16 sync blocks.
Bit sync, 24-bit ID, 8-bit header,
It is composed of 760-bit main data and 80-bit parity C1. The sync is generated by the sync generator 7. The ID is added by the error code ID adding unit 5. The header includes identification information for identifying whether the main data is audio data, video data, search video data, transport stream data, AUX data, or the like. The header data is supplied from the terminal 3 by the controller 13 as a type of system data.

When the main data is video data,
The data is supplied from the video data compression unit 1, and is supplied from the audio data compression unit 2 when the data is audio data, and is supplied from the controller 13 via the terminal 3 when the data is AUX data.

The parity C1 is obtained from the ID, header, and main data of each sync block based on the error code ID.
Calculated and added by the adding unit 5.

The last 18 sync blocks of the 141 sync blocks have a sync, ID, and parity C2.
And C1. The parity C2 is obtained by calculating the header or main data in the vertical direction in FIG. This calculation is performed in the error code ID adding unit 5.

The total data amount of the main sector is 888 bits × 141 sync blocks = 125208 bits, and the total data amount after 24-25 conversion is 130425 bits. The practical maximum data rate is
When the rotation of the rotary head 12 is synchronized with 60 Hz,
760 bits x 123 sync blocks x 10 tracks x
30 Hz = 28.044 MHz. This bit rate is a rate sufficient to record HG video data, audio compression data, AUX data, and video data for search according to MP @ HL or MP @ H-14.

Subsequent to the main sector, a 1250-bit subcode sector is arranged. The structure of this subcode sector is shown in FIG.

A subcode sector of one track is composed of ten subcode sync blocks, and one subcode sync block is composed of a sync, an ID, subcode data, and a parity.

The length of 1250 bits (24
At the head of each subcode sync block of the subcode sector of (length after −25 conversion), a 16-bit sync with a length before being subjected to the 24-25 conversion is arranged.
A 4-bit ID is arranged. The sink is a sink generator 7
And the ID is added by the error code ID adding unit 5.

Subsequent to the ID code, 40-bit subcode data is arranged. The subcode data is supplied from the controller 13 via the terminal 3 and includes, for example, a track number, a time code number, and the like. Following the subcode data, a 40-bit parity is added. This parity is the error code ID
It is added by the adding unit 5.

The data of the 120-bit subcode sync block before being subjected to the 24-25 conversion is subjected to the 24-25 conversion to become 125 (= 120 × 25/24) bits.

After the subcode sector, a postamble is arranged. This postamble is also recorded by combining pattern A and pattern B shown in FIG. Its length is 1500 bits when synchronizing with 60 × 1000/1001 Hz, and 1 bit when synchronizing with 60 Hz.
It is 375 bits.

Next, the operation of the apparatus shown in FIG. 3 will be described. The HD video signal is input to the video data compression unit 1 together with search video data (thumbnail video data), and is compressed by, for example, the MP @ HL or MP @ H-14 method. The audio signal is input to the audio data compression unit 2 and is compressed in the same manner as in the DV format. The terminal 3 is supplied with system data such as subcode data, AUX data, and header from the controller 13.

The switch 4 is controlled by the controller 13, and outputs the video data (including video data for search) output from the video data compression unit 1 and the audio data compression unit 2.
The audio data output from the terminal or the system data input from the terminal 3 is taken in at a predetermined timing and output to the error code ID adding unit 5 to synthesize these data.

The error code ID adding section 5 adds a 24-bit ID to each sync block shown in FIG. 10 of the main sector. Further, the parity C1 shown in FIG. 10 is calculated and added for each sync block, and a parity C2 is added to the last 18 sync blocks of the 141 sync blocks instead of the header and the main data.

As shown in FIG. 11, the error code ID adding section 5 adds a 24-bit ID to each sub-code sync block of the sub-code data, calculates a 40-bit parity, and adds I do.

The error code ID adding unit 5 further holds 16 tracks of data for main sector data and interleaves the data between 16 tracks (sub code data is not interleaved).

The 24-25 conversion unit 6 converts the data in 24-bit units supplied from the error code ID adding unit 5 into data in 25-bit units. As a result, FIGS.
, The components of the tracking pilot signal of the frequencies f1 and f2 appear strongly.

As shown in FIG. 10, the sync generator 7
In each sync block of the main sector, one redundant bit is added to 16 bits and 17 bits after 24-25 conversion are added.
Add a bit sync. In addition, the sync generation unit 7
As shown in FIG. 11, a 17-bit sync after 24-25 conversion in which one redundant bit is added to 16 bits is added to each sub-code sync block of a sub-code sector. Further, the sync generator 7 generates a preamble or postamble run pattern shown in FIG.

More specifically, the addition (synthesis) of these data is performed by the controller 13 by switching the switch 8 and the data output from the sync generator 7 and
5 The data output from the conversion unit 6 is appropriately selected, and the modulation unit 9 is selected.
This is done by supplying to.

The modulator 9 randomizes the input data, modulates the data by a method corresponding to the DV format, and outputs the modulated data to the parallel-serial converter 10. The parallel-to-serial conversion unit 10 converts the input data from parallel data to serial data, and supplies the serial data to the rotary head 12 via the amplifier 11. The rotating head 12
The input data is recorded on the magnetic tape 21.

FIG. 12 shows an example of the configuration of a reproducing system for reproducing data recorded on the magnetic tape 21 as described above.

The rotary head 12 reproduces data recorded on the magnetic tape 21 and outputs the data to the amplifier 41. The amplifier 41 amplifies the input signal and supplies it to the A / D converter 42. The A / D converter 42 converts the input signal from an analog signal to a digital signal, and supplies the digital signal to the demodulator 43. The demodulation unit 43 converts the data supplied from the A / D conversion unit 42 into
The signal is de-randomized in response to the randomization in the modulation unit 9 and demodulated by a method corresponding to the modulation method in the modulation unit 9.

From the data demodulated by the demodulation unit 43, the sync detection unit 44 determines the sync of each sync block of the main sector shown in FIG. 10 and the sync of each subcode sync block of the subcode sector shown in FIG. Detected and supplied to the error correction ID detection unit 46. The 25-24 conversion unit 45 converts the data supplied from the demodulation unit 43 into 24-
In accordance with the conversion in the 25 conversion unit 6, the data is converted from data in units of 25 bits to data in units of 24 bits and output to the error correction ID detection unit 46.

The error correction ID detector 46 is provided with the sync detector 4
Error correction processing, ID detection processing, and deinterleave processing are executed based on the sink input from step 4. Switch 47
Is controlled by the controller 13, outputs video data (including video data for search) of the data output from the error correction ID detection unit 46 to the video data decompression unit 48, and converts the audio data to the audio data decompression unit. 49 to output system data such as subcode data and AUX data.
The signal is output from the terminal 50 to the controller 13.

The video data decompression unit 48 decompresses the input video data, performs D / A conversion, and outputs it as an analog HD video signal. The audio data expansion unit 49 expands the input audio data, performs D / A conversion, and outputs the analog data as an analog audio signal.

Next, the operation will be described. The rotating head 12 reproduces the data recorded on the magnetic tape 21 and amplifies the data by the amplifier 41.
Feed to 2. The data converted from the analog signal to the digital data by the A / D conversion section 42 is input to the demodulation section 43, where the data is derandomized and demodulated in a manner corresponding to the randomization and modulation scheme in the modulation section 9 in FIG. You.

The output of the A / D converter 42 is also supplied to a servo circuit (not shown), where the data of pattern A and pattern B recorded in the preamble and postamble (FIG. 9) are reproduced. , A pilot signal for tracking is generated, and tracking control is executed.

The 25-24 conversion section 45 converts the data demodulated by the demodulation section 43 from the data in units of 25 bits into two.
The data is converted into 4-bit data, and an error correction ID
Output to

The sync detector 44 detects the sync of the main sector shown in FIG. 10 or the sync of the subcode sector shown in FIG. 11 from the data output from the demodulator 43, Supply. Error correction
The ID detection unit 46 stores main data for 16 tracks, performs deinterleaving processing, and performs error correction processing using the parity C1 and C2 of the main sector shown in FIG. Further, the error correction ID detection unit 46 detects the ID of the main sector, and determines whether the data included in each sync block is audio data, video data, AUX data, video data for search, or the like. I do.

The error correction ID detection section 46 performs error correction processing on the subcode data using the parity of the subcode sector shown in FIG. 11, detects the ID, and determines the type of the subcode data. I do. This makes it possible to determine whether the subcode data represents a track number or a time code number.

The switch 47 supplies video data and search data to the video data decompression unit 48 based on the ID detected by the error correction ID detection unit 46. The video data decompression unit 48 decompresses the input data in a format corresponding to the compression format in the video data compression unit 1 in FIG.
Output as a video signal.

The switch 47 outputs the audio data to the audio data decompression unit 49. The audio data decompression unit 49 is configured as shown in FIG.
The audio data inputted by the method corresponding to the compression method in the audio data compression unit 2 is expanded and output as an audio signal.

The switch 47 is connected to the error correction ID detecting section 4.
AUX data, subcode data, and the like output from 6 are output from the terminal 50 to the controller 13.

Next, the subcode sync block of the subcode sector will be further described.

Assuming that the length of one sync block before the 24-25 conversion is 15 bytes (120 bits), its value is a multiple of 24, and as shown in FIG.
The break of the sync block of the five conversions coincides with the head of the next sync block. As a result, signal processing becomes easy.

Further, the error correction code in the sink (parity C
As shown in FIG. 11, 1) is a total of 13 bytes of ID of 3 bytes (24 bits), main data of 5 bytes (40 bits), and parity C1 of 5 bytes (40 bits).
By byte, Galois field GF (2 ⁸⁾ (13,
8,6) Reed-Solomon code or Galois field
A (13,8,6) Reed-Solomon code of GF (2 ⁴ ) is configured.

FIG. 14 shows the configuration of a (13,8,6) Reed-Solomon code of Galois field GF (2 ⁸ ). As shown in the figure, each of the data S is constituted by ID0, ID1, and ID2, each of which constitutes a 3-byte ID, each having 1-byte.
0, S1, and S2, and data S3 to S7 are composed of 5-byte main data. These 8-byte data S0 to S7 have a 5-byte parity P0.
To P4, and a total of 13 bytes constitute a (13, ⁸ , 6) Reed-Solomon code of the Galois field GF (2 ⁸ ).

In this example, the data S0 to S7 and the parities P0 to P4 are sequentially arranged on the magnetic tape 21 in that order.

FIG. 15 shows a two-sided configuration of a (13,8,6) Reed-Solomon code of Galois field GF (2 ⁴ ). In the example of FIG. 15, one byte ID0 of the three-byte ID is divided into the MSB side 4-bit data S0 and the LSB side 4-bit data S1. Similarly, ID1 and ID
2 is also divided into data S2 and S4 on the MSB side and data S3 and S5 on the LSB side, respectively. Further, the 5-byte main data is also used for the MSB side data S6, S8, S10, S1.
2, S14 and LSB side data S7, S9, S11, S
13, S15.

Then, the data S0 to S0 on the MSB side of one surface
7 is calculated with 5-byte parities P0 to P4,
Then, 5-byte parities P5 to P9 are calculated and added to the data S8 to S15 on the LSB side of the other surface.

The data (S0, S8) is stored on the magnetic tape.
(S1, S9) (S2, S10) (S3, S11) (S
4, S12) (S5, S13) (S6, S14) (S
7, S15) (P0, P5) (P1, P6) (P2, P
7) Recording is performed in the order of (P3, P8) (P4, P9).

FIG. 16 shows another example of the two-sided configuration of the (13, 8, 6) Reed-Solomon code of the Galois field GF (2 ⁴ ). The data division and the surface configuration are the same as those shown in FIG. 15, but the order of recording on the magnetic tape 12 is different from that in FIG. In the example of FIG. 16, (S0, S1) (S2, S3) (S4,
S5) (S6, S7) (S8, S9) (S10, S1)
1) (S12, 13) (S14, S15) (P0, P
1) (P2, P3) (P4, P5) (P6, P7) (P
8, P9).

FIG. 17 shows still another example. Also in this example, the data division and the configuration of the plane are the same as those in FIG. 15, but in this example, the parity and the ID or the main data are distributed and arranged on the magnetic tape 12. That is, the data is (S0, S1) (S
2, S3) (S4, S5) (S6, S7) (P0, P
1) (P2, P3) (P4, S8) (S9, S10)
(S11, S12) (S13, S14) (S15, P
5) (P6, P7) (P8, P9).

When the bit error probability when the recorded bit data sequence is reproduced is Pb, the Galois field
The single error probability P _S1 of GF (2 ⁸ ) is expressed by the following equation.

P _S1 = 1− (1−Pb) Probability that the (13,8,6) Reed-Solomon code of the ⁸ Galois field GF (2 ⁸ ) is not correctly decoded (cannot be decoded or erroneously decoded) When P ₁ is obtained, it becomes as follows.

[0088]

(Equation 1)

Similarly, the single error probability P _S2 of the Galois field GF (2 ⁴ ) is expressed by the following equation.

P _S2 = 1− (1−Pb) The probability P ₂ that the (13,8,6) Reed-Solomon code of the ⁴ Galois field GF (2 ⁴ ) is not correctly decoded is calculated as follows.

[0091]

(Equation 2)

The probabilities P ₁ and P ₂ that are not correctly decoded are represented by
FIG. 18 shows a comparison with the probability P ₃ of the normal decoding of the (14, 10, 5) Reed-Solomon code of the Galois field GF (2 ⁴ ) in the sync block of the DV format subcode.

In FIG. 18, curve A represents the probability P ₁ , curve B represents the probability P ₂ , and curve C represents the probability P ₃ .

The limit bit error probability of 1.0 when the magnetic tape recorded in the DV format is reproduced is considered to be 1.0.
The probability of non-normal decoding near E ^-4 is approximately 1E-10.5 for curve A or B, whereas it is approximately 1E-09.5 for curve C. That is, in the latter, the probability of not being correctly decoded is reduced by about one digit compared to the former.

The probability Q of erroneous correction is simply determined by the number N of parity bits and is expressed by the following equation.

The number of parity bits in the Q = 1 / ^2N DV format is 4 × 4 =
Since there are 16 bits, the probability of erroneous correction Q _DV is expressed by the following equation.

Q _DV = 1.5E ^-5 In contrast, the Galois field GF (2 ⁴ ) of the present invention
Is 4 × 10 = 40 bits, and the number of parity bits in the Galois field GF (2 ⁸ ) is 8 × 5 = 40 bits. In these cases, the probability of incorrect correction Q _IN is: It is expressed by the following equation.

Q _IN = 9.1E ^{-13 In} other words, it can be seen that the result of the present invention is about eight orders better than that of the DV format.

When the Reed-Solomon code of the Galois field GF (2 ⁸ ) has the limit of correction, four symbols are used out of the parity of five symbols. Therefore, after performing the correction, it is possible to detect an error (check the certainty of the correction) using the remaining parity 1 symbol.

From the above, it can be said that the format according to the present invention is more resistant to erroneous correction and erroneous detection than the DV format.

As described above, when recording / reproducing data compressed by the MPEG method or the like, the recording / reproducing format using the sync block according to the present invention has the following advantages over the method using the DV format. Have.

1. Error tolerance against erroneous correction and erroneous detection is improved, and data corruption due to error rate deterioration in search or the like can be detected.

2. Since the ID is also included in the Reed-Solomon code, the reliability in checking the continuity of the sync block number, the track number, and the like included in the ID increases.

3. Therefore, redundancy such as multiplex recording of the same data in a plurality of sync blocks in one track as in the DV format can be suppressed low, and various types of data can be recorded in one track. Further, since the number of erroneous corrections and erroneous detections is reduced, it is not necessary to check continuity with past data, and both hardware and software can be lightened.

4. Since the 24-25 conversion of the DV format can be used as it is, it is easy to construct a system based on the DV system.

As described above, the present invention is useful not only for a digital video cassette but also as a format for recording and reproducing information attached to compressed data such as the MPEG format on a tape medium.

The above-described series of processing can be executed by hardware, but can also be executed by software. When a series of processing is executed by software, a program constituting the software executes various functions by installing a computer built in dedicated hardware or installing various programs. For example, it is installed from a recording medium to a general-purpose personal computer or the like.

As shown in FIG. 3 and FIG. 12, this recording medium is provided separately from the magnetic tape recording / reproducing apparatus main body and distributed to provide the user with the program. Optical disk 32 (including floppy disk), CD-ROM (Compact Disk-Read Onl
y Memory), a DVD (including a Digital Versatile Disk), a magneto-optical disk 33 (including an MD (Mini-Disk)), or a package medium including a semiconductor memory 34, etc. It is composed of a ROM in which programs are provided and a hard disk, etc., which are provided to the user in an embedded state.

[0109] In this specification, the step of describing a program recorded on a recording medium may be performed in a chronological order according to the described order. This also includes processing executed in parallel or individually.

[0110]

As described above, according to the magnetic tape recording apparatus and method, the magnetic tape format, and the recording medium program of the present invention, each track has a 2-byte detection pattern, 3-byte identification information, A byte of main data and a 5-byte parity are arranged, and the (13,8,6) Reed-Solomon code of the Galois field GF (2 ⁸ ) or a Galois field GF of a two-sided configuration is used according to the identification information, the main data and the parity. Since the (13, 8, 6) Reed-Solomon code of (2 ⁴ ) is configured, it is possible to realize a format that is more resistant to erroneous correction and erroneous detection than the DV format.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the configuration of a track sector in the DV format.

FIG. 2 is a diagram illustrating a configuration of a subcode sector in FIG.

FIG. 3 is a block diagram illustrating a configuration example of a recording system of a magnetic tape recording / reproducing apparatus to which the present invention has been applied.

FIG. 4 is a diagram illustrating a track format of the magnetic tape of FIG. 3;

FIG. 5 is a diagram illustrating a tracking pilot signal recorded on the track of FIG. 4;

FIG. 6 is a diagram illustrating a tracking pilot signal recorded on the track of FIG. 4;

FIG. 7 is a diagram illustrating a tracking pilot signal recorded on the track of FIG. 4;

FIG. 8 is a diagram illustrating the sector arrangement of the track in FIG. 4;

FIG. 9 is a diagram illustrating patterns of a preamble and a postamble in FIG. 8;

FIG. 10 is a diagram illustrating a configuration of a main sector in FIG. 8;

FIG. 11 is a diagram illustrating a configuration of a subcode sector in FIG. 8;

FIG. 12 is a block diagram illustrating a configuration example of a reproducing system of a magnetic tape recording / reproducing apparatus to which the present invention has been applied.

FIG. 13 is a diagram illustrating the relationship between the length of a sync block and a 24-25 conversion cycle.

FIG. 14: (13, 8,) of Galois field GF (2 ⁸ )
6) is a diagram illustrating a Reed-Solomon code.

FIG. 15 shows (13, 8,) of Galois field GF (2 ⁴ ).
6) A diagram illustrating an example of a two-sided configuration of a Reed-Solomon code.

FIG. 16 shows (13, 8,) of Galois field GF (2 ⁴ ).
6) A diagram illustrating an example of a two-sided configuration of a Reed-Solomon code.

FIG. 17: (13, 8,) of Galois field GF (2 ⁴ )
6) A diagram illustrating an example of a two-sided configuration of a Reed-Solomon code.

FIG. 18 is a graph showing the probability of not being correctly decoded.

[Explanation of symbols]

1 video data compression unit, 2 audio data compression unit, 5
Error code ID addition unit, 624-25 conversion unit, 7 sync generation unit, 9 modulation unit, 21 magnetic tape, 4
3 demodulation unit, 45 25-24 conversion unit, 44 sync detection unit, 46 error correction ID detection unit, 48 video data expansion unit, 49 audio data expansion unit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G11B 20/18 572 G11B 20/18 572G 574 574F H04N 5/7826 H04N 5/782 D 5/92 5/92 HF term (reference) 5C018 CA02 5C053 FA17 FA22 GA11 GB15 GB25 JA03 5D031 AA04 EE07 HH20 5D044 AB05 AB07 BC01 CC03 DE04 DE22 DE32 DE34 DE57 DE70 DE73 EF05

Claims (5)

[Claims] 1. A magnetic tape recording apparatus for recording digital data on a track of a magnetic tape by a rotating head, comprising: a first unit including video data, audio data, or search data;
And a second group of data including subcode data related to the data of the first group, each of which is provided with a code for error correction, and each of the data is provided on a track of the magnetic tape. Formatting means for formatting the two so that they are continuous without being separated from each other, and supply means for supplying data formatted by the formatting means to the rotary head for recording on the magnetic tape The formatting means arranges a plurality of sync blocks each having a length of 15 bytes, one for each track, for the data of the second group. The detection pattern for block detection is 2 bytes, the identification information for identifying the sync block is 3 bytes, and the main data is 5 bytes. 5 bytes are arranged for the byte and the parity for the identification information and the main data, and (13, ^{8, 6} ) of the Galois field GF (2 ⁸ ) is determined by the identification information, the main data, and the parity.
A magnetic tape recording apparatus comprising a Reed-Solomon code or a Galois field GF (2 ⁴ ) (13,8,6) Reed-Solomon code having a two-sided configuration. 2. The magnetic tape recording apparatus according to claim 1, wherein said formatting means arranges ten sync blocks continuously on one track. 3. A magnetic tape recording method for a magnetic tape recording device for recording digital data on a track of a magnetic tape by a rotating head, wherein the first method includes video data, audio data or search data.
And a second group of data including subcode data related to the data of the first group, each of which is provided with a code for error correction, and each of the data is provided on a track of the magnetic tape. A formatting step of formatting the two so that they are continuous without being separated, and a supply step of supplying data formatted by the processing of the formatting step to the rotary head for recording on the magnetic tape. In the processing of the formatting step, a plurality of sync blocks each having a length of 15 bytes are continuously arranged in each track for the data of the second group; The block has a detection pattern for sync block detection of 2 bytes and identification information for identifying the sync block. Information, 3 bytes of main data, and 5 bytes of parity for the identification information and the main data. According to the identification information, the main data, and the parity, (13,) of the Galois field GF (2 ⁸ ) 8,6)
A magnetic tape recording method comprising forming a Reed-Solomon code or a (13,8,6) Reed-Solomon code of Galois field GF (2 ⁴ ) having a two-sided configuration. 4. A program for a magnetic tape recording apparatus for recording digital data on a track of a magnetic tape by a rotating head, wherein the first program includes video data, audio data or search data.
And a second group of data including subcode data related to the data of the first group, each of which is provided with a code for error correction, and each of the data is provided on a track of the magnetic tape. A formatting step of formatting the two so that they are continuous without being separated, and a supply step of supplying data formatted by the processing of the formatting step to the rotary head for recording on the magnetic tape. In the processing of the formatting step, a plurality of sync blocks each having a length of 15 bytes are continuously arranged in each track for the data of the second group; The block has a detection pattern for sync block detection of 2 bytes and identification information for identifying the sync block. Information, 3 bytes of main data, and 5 bytes of parity for the identification information and the main data. According to the identification information, the main data, and the parity, (13,) of the Galois field GF (2 ⁸ ) 8,6)
A recording medium on which a computer-readable program for forming a Reed-Solomon code or a (13, 8, 6) Reed-Solomon code of Galois field GF (2 ⁴ ) having a two-sided configuration is recorded. 5. A magnetic tape format in which digital data is recorded on tracks by a rotating head, wherein the first format includes video data, audio data or search data.
And a second group of data including subcode data related to the data of the first group, an error correction code is added to each of the data, and each of the data is provided between the two on the track. Are formatted to be continuous without spacing, and for each track, for the second group of data,
A plurality of sync blocks each having a length of 15 bytes are continuously arranged, and one sync block has a detection pattern for detecting a sync block of 2 bytes and identification information for identifying a sync block of 3 bytes. , 5 bytes of main data, and 5 bytes of parity for the identification information and the main data. According to the identification information, the main data, and the parity, (13, ^{8, 6} ) of the Galois field GF (2 ⁸ )
A magnetic tape format comprising a Reed-Solomon code or a Galois field GF (2 ⁴ ) (13,8,6) Reed-Solomon code having a two-sided configuration.