JP2640342B2 - PCM recording / reproducing device and PCM reproducing device - Google Patents

Description

The present invention relates to a PCM recording / reproducing apparatus for recording an encoded PCM signal on a magnetic tape and reproducing the recorded magnetic tape, and an apparatus for reproducing the magnetic tape. It relates to a PCM playback device to be used.

[Conventional technology]

As this type of PCM recording / reproducing device, there are known a device that records a PCM signal as a track inclined on a magnetic tape by a rotating head and a device that records a PCM signal as a track extending in the longitudinal direction of a magnetic tape by a fixed head. Have been. The present invention is applied to the latter device, and makes it possible to reliably and easily detect a hand-cut editing point.

FIG. 6 shows a conventional PCM disclosed in JP-A-56-37870.
FIG. 3 is a diagram showing a recording format of the recording / reproducing device. 1
Is a magnetic tape, and 2 to 9 are recording tracks. Analog-to-digital conversion and time-aligned PCM signal train Dn
Then, the PCM signal sequence Dn is delayed by several blocks (l unit in the figure) for each track and arranged in the arrangement shown in the figure.

In track 2, an error check code (often a shortened cyclic code CRCC is often used) P is added to D ₁ , D ₇ ,... D ₃₇ , and a synchronization signal S is added to form a frame. Tracks 3 to 7 have the same configuration. Also, check symbols to Q ₁ appended error correction code for a given in track 8 of the PCM signal sequence (e.g., Reed-Solomon code), Q _3, ... error check code P is added to Q _13, synchronization The signal S is added to form a frame. Track 9 is similar to track 8. A collection of frames from track 2 to track 9 is called a block.

Next, FIG. 7 shows the arrangement of the PCM signal and the arrangement of the check symbols Q of the correction code in an easy-to-understand manner. As described above, the PCM signal trains Dn arranged in time are arranged at intervals of several l blocks as shown in the figure. This is called interleaving and has a function of dispersing errors caused by scratches or defects on the tape. As will be described later, the PCM signal before the editing and the PCM signal after the editing are doubled for a certain period using the correction means near the editing point, the data before the editing are faded out, and the data after the editing point are faded in. There are also functions such as performing a crossfade by connecting them, so that signals can be smoothly connected before and after the edit point.

FIG. 8 is a schematic block diagram of a conventional PCM recording / reproducing apparatus. In the figure, 10 is an analog signal input terminal, 11 is an analog / digital (A / D) converter, 12 is an error correction coding circuit (Q code), 13 is a track distribution circuit, 14 is an interleave circuit, and 17 is an error check. Encoding circuit (P code), 18 is PCM
A modulation circuit such as an MFM for recording a signal, 19 is a recording head, 20 is a reproduction head, 21 is a demodulation circuit for demodulating an output reproduced from the reproduction head to a PCM signal, and 22 is an error detection circuit for a reproduction PCM signal ( P code), 25 is a de-interleave circuit that restores track-delayed data, 26 is multi-track
A track synthesizing circuit for arranging PCM signals in a time-series signal; 27, a decoding circuit for performing error correction of a Q code; 34, a first edit detection circuit for detecting an edit point based on a detection result of a P code check circuit 22; A second edit detection circuit for detecting an edit point based on the result of the decoding circuit of No. 28; an edit processing circuit 28 for connecting the PCM signal near the edit point without skipping the level by a control signal from the edit detection circuits 34 and 35;・ Analog (D / A) converter, 30 is analog signal output terminal.

Next, the operation of the conventional PCM recording / reproducing apparatus having such a configuration will be described.

The analog signal input from the input terminal 10 is converted into a PCM signal by the A / D converter 11. In the encoding circuit 12,
A check symbol Q is added to the PCM signal sequence Dn. Track distribution circuit 13, interleave circuit 14,
It is converted into a PCM signal array as shown in FIGS. Further, an error check code P is coded for each track by a P coding circuit 17, a synchronization signal S is further added, and sent to a modulation circuit 18. The modulation circuit 18 modulates the data into a form recordable on a magnetic tape, and records the data on the magnetic tape 1 via a recording head 19.

Next, the operation on the reproduction side will be described. The signal read by the reproducing head 20 is converted into a PCM signal by a demodulation circuit 21, an error is detected by a P code check circuit 22, and a de-interleave circuit
25, through the track synthesis circuit 26, further performs error detection and error correction in the Q code decoding circuit 27, and performs time-series PCM
Signal.

In the case of performing normal reproduction without a hand-cut editing point, the PCM signal output from the decoding circuit 27 is output as it is in the editing processing circuit 28, converted into an analog signal by the D / A converter 29, and output to the analog output terminal 30. Output. When playing back a magnetic tape that has been hand-cut and edited, the P-code check result is used, which focuses on the fact that at the editing point, errors are intensively generated at the same position in the vertical direction of a plurality of tracks due to vertical cutting. The control output of the first edit detection circuit 34 is sent to the edit processing circuit 28. On the other hand, since the Q code is coded for the PCM signal subjected to track delay as shown in FIG. 7, if a truncated edit point is present in the code, the code will not be consistent before and after the edit point. The control output of the second edit detection circuit 35 paying attention to the above is similarly sent to the edit processing circuit 28. The edit processing circuit 28 executes an edit process when a control signal is output from both the first edit detection circuit 34 and the second edit detection circuit 35.

The output of the edit processing circuit 28 is converted into analog data by a D / A converter 29 and output from an analog output terminal 30.

In the vicinity of the cut point, the PCM signal is delayed between tracks.
The edited PCM signal can be generated twice using the correction means for a certain period. FIG. 9 shows the reproduced signal before and after the editing point. Assuming that the left side of the editing point is the A tape and the right side is the B tape as shown in FIG. 9 (a), the reproduced signal of this tape can create an overlapping section of j blocks as shown in FIG. 9 (b). The reproduction signal of the A tape is made to fade out, and the reproduction signal of the B tape is made to fade in, so that cross-fading is performed, thereby preventing a level jump of the reproduction signal. The crossfade section j is usually related to the interleave length, and in the interleave shown in FIG. 7, the relationship of 3l <j is established. So far, the format and configuration of the PCM recording / reproducing apparatus have been described, but the conventional PCM recording / reproducing apparatus has the following problems.

FIG. 10 (a) shows a state where a magnetic tape on which hand-cut editing has been actually performed is reproduced. 3b is a splicing tape, which serves to connect the two tapes.
The ends of the splicing tape 3b are a and c, the editing point is b, and the interval between ab and bc is k blocks. If you play the tape connected with the splicing tape 3b here,
An error may occur in the vertical direction at both ends of the splicing tape 3b. It is considered that this is because the tape thickness changes due to the splicing tape 3b, and the contact pressure to the head changes. FIG. 10 (b) shows the output of the first edit detection signal and the second edit detection signal in such a case.

The output of the first edit detection signal is output to both ends a and c of the splicing tape 3b and the edit point b. On the other hand, the output of the second edit detection signal is at an interval sufficiently wider than k. Therefore, the edit processing circuit 28 cannot determine whether the edit point is a, b, or c. When the cross-fade interval j is smaller than k, the edit point is erroneously determined to be a or c. ,
In some cases, the cross-fade is not performed at the original editing point and the editing process is not performed.

Also, as shown in FIG. 11 (a), when playback is performed on a tape on which hand-cut editing has not been performed vertically, the first edit detection signal is erroneously concentrated at the same position in the vertical direction. Therefore, as shown in FIG. 11 (b), the first edit detection signal is not output and the edit processing circuit 28 does not perform the edit.

[Problems to be solved by the invention]

As described above, the conventional PCM recording / reproducing apparatus may not be able to perform accurate editing processing. In addition, there is another inconvenience that the editing process cannot be performed when the hand-cut editing is performed diagonally.

Japanese Patent Application Laid-Open No. Sho 57-36476 discloses a proposal for making it possible to reliably detect an edit point. This provides a control track separately from the track for data recording,
Here, an address which advances in the longitudinal direction of the tape is recorded.

When the tape editing is performed, the address becomes discontinuous, so that the discontinuity can be detected as an editing point. However, in such a system, it is necessary to reduce the data track width in order to provide the control track.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and it is possible to accurately detect a hand-cut editing position and perform the editing process reliably. And can cope with data errors without further reducing the track width.
It is an object to obtain a PCM recording / reproducing device and a PCM reproducing device.

[Means for solving the problem]

A PCM recording / reproducing apparatus according to a first aspect of the present invention distributes digital data of one or more channels as a frame configuration in which a synchronization signal is added to a plurality of tracks arranged side by side in a tape width direction, and a frame of a plurality of tracks is divided into one block. In a PCM recording / reproducing apparatus for recording and reproducing the same, a second encoding means for adding an error correction code in the tape width direction to the input one block of digital data, and a second encoding means Interleaving means for interleaving the digitized digital data, means for adding continuous block addresses in block units in the tape width direction in each block, and error checking codes in the tape longitudinal direction for the interleaved digital data. And a first encoding means for adding the Recording means for modulating and recording one block of digital data to which an address has been added, demodulating means for demodulating digital data reproduced from a magnetic tape, and first decoding for decoding the demodulated digital data based on an error check code Means, de-interleaving means for performing a de-interleaving process on the decoded digital data, second decoding means for decoding the de-interleaved digital data based on an error correction code, and said first decoding means. Edit detection means for extracting a block address from the decoded digital data and determining discontinuity of the block address at a predetermined interval or more as an edit point; and when the edit detection means detects the edit point, the edit point Edit processing means for editing the nearby digital data.

The PCM playback apparatus according to the second invention distributes interleaved single or multiple channels of digital data as a frame configuration in which a synchronization signal is added to a plurality of tracks arranged side by side in the tape width direction, and Is recorded as one block, and the recorded 1
The digital data of a block is obtained from a magnetic tape in which an error check code is added in the longitudinal direction of the tape, an error correction code is added in the width direction of the tape, and a block address continuous in block units is added in the width direction of the tape in each block. In a PCM reproducing apparatus for reproducing digital data, demodulating means for demodulating digital data reproduced from the magnetic tape, first decoding means for decoding demodulated digital data based on an error check code, and decoding of the decoded digital data. Deinterleaving means for performing interleaving processing, second decoding means for decoding the deinterleaved digital data based on an error correction code, and a block address from the digital data decoded by the first decoding means. Extract the block address And editing detecting means for judging continuity and edit point, when the editing detecting means detects an edit point,
Edit processing means for editing digital data near the edit point.

[Action]

The PCM recording / reproducing apparatus according to the present invention can detect an accurate editing position by detecting a discontinuity of a block address, and further detects a discontinuity of a block address even when edited in an oblique direction. Almost the center position of editing can be detected, and reliable editing processing can be performed.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a recording format of a PCM recording / reproducing apparatus according to the present invention. The symbols in the figure have the same meaning as in FIG. 6, where D is a PCM signal sequence, P is an error check code in the tape longitudinal direction, Q is an error correction code in the tape width direction, and S is a synchronization signal. B is a block address area newly added in the present invention. The block is now composed. Although not shown, it is needless to say that the PCM signal D is interleaved as in the conventional example in order to disperse errors and to enable crossfading at the editing point.

FIG. 2 shows the contents of the block address area B. (A) is a format to which an error correction code R is added to improve the reliability of a block address. (B) also relates to the capacity of the block address area. However, the ID code (Identification Data) for recording the sampling frequency and the tape speed related to the system of the PCM recording / reproducing apparatus and the block address are combined into one. On the other hand, this is a format to which an error correction code R is added. (A) and (b) Both formats have the same effect, but in the following description, (a) will be assumed.

In FIG. 1, if the error check code P is also applied to the block address area B, the block address has a double error correction code, and the reliability can be further improved.

FIG. 3 is a schematic block diagram of one embodiment of the present invention. 16 is a continuous block address generator, 15 is an R encoding circuit for adding an error correction code R shown in FIG. 2 (a) to the block address generated in 16, and 23 is a block address of the block address. R code decoding circuit for correcting errors, 24
Is an edit detection circuit for detecting discontinuity of the block address from the block address and performing edit detection.

Hereinafter, description will be given along the flow of signals. The analog signal input from the input terminal 10 is converted into a PCM signal by the A / D converter 11, and an error correction code in the tape width direction is added by the Q encoding circuit 12. Next, an R-encoded circuit 15 adds an error-corrected code to a continuous block address generated by a block address generator 16 via a track distribution circuit 13 and an interleave circuit 14. Further, a P encoding circuit 17 encodes the error check code P, adds a synchronizing signal S, and generates a modulation circuit.
Modulation is performed at 18, and the data is recorded on the magnetic tape 1 through the recording head 19. On the reproduction side, the signal read by the reproduction head 20 is modulated into a PCM signal by the demodulation circuit 21 and an error is detected by the P code check circuit. Further, the block address is subjected to error correction by the R code decoding circuit 23 and sent to the edit detection circuit 24. On the other hand, the PCM signal becomes a time-series PCM signal through a de-interleave circuit 25 and a track synthesizing circuit 26. The Q code decoding circuit 27 corrects the error of the PCM signal, and is sent to an edit processing circuit 28. In the case of performing normal reproduction without a hand-cut editing point, the editing processing circuit 24 does not output any signal, and the PCM signal output from the Q code decoding circuit 27 is output as it is by the editing processing circuit 28, and the D / A The signal is converted into an analog signal by the converter 29 and output from the analog output terminal 30.
In the case of reproduction with a truncated point, the block addresses become discontinuous at the edit points, and the edit detection circuit 24 can accurately detect the edit points. The detection signal is sent to an editing processing circuit 28, and performs a predetermined editing process such as crossfading, and is converted into an analog signal by a D / A converter 29,
Output from the output terminal 30. Note that the PCM reproducing apparatus according to the present invention includes the reproducing head 20 to the output terminal 30, and does not include a recording system.

FIG. 4 is a diagram showing the edit detection circuit 24 in detail.
31 is a synchronous load type counter, and 32 is a difference comparator that outputs when the difference between the two input signals A and B is larger than a predetermined value. In operation, the block address is sent from the R code decoding circuit 23 and is connected to the load input terminal of the counter 31. At the same time, a block address correction signal is sent from the R code decoding circuit 23 to inform whether or not the block address transferred is correct. If the polarity is correct, it is at the L level. Correct block
When an address is being transferred, that is, when the block address correction signal is L, the counter 31 operates to sequentially latch the immediately preceding data in synchronization with the block clock. If the block address m (m: integer) is input to the input terminal A of the difference comparator 32, the block address m-1 is input to the other input terminal B. When an incorrect block address is transferred, that is, when the block address correction signal is H,
The counter 31 stops the loading operation, uses the property of block address continuation, and increases the previous loading value by one to generate the counter. The block address is corrected by the R code decoding circuit 23, and for those which cannot be corrected, the counter 31 is used to correct the block address, so that the block address becomes highly reliable. Next, the difference comparator 32 executes the calculation of AB, and if the absolute value of the result is larger than the predetermined value P, determines that the block address is discontinuous and outputs an edit point detection signal. Has become. Here, the predetermined value P is theoretically that all AB ≠ 1 are discontinuous. However, due to the configuration of the PCM reproducing apparatus, the block address may jump slightly to absorb reproduction jitters and the like. Therefore, the expression of the predetermined amount P is used. However, the predetermined amount P is at most several blocks.
As the size of the block address increases, the accuracy improves as the size increases, but it cannot be realized because the circuit scale is large. With about 16 bits, the probability of false detection is low, and the circuit scale is reasonable, so there is no practical problem.

FIG. 5 (a) shows a state in which the magnetic tape 1 on which the hand-cut editing has been actually performed is reproduced. In a conventional PCM recording / reproducing apparatus, an edit detection signal is also output from points a and c at both ends of the splicing tape. However, in the PCM recording / reproducing apparatus of the present invention, an edit detection signal can be obtained only from the edit point b. FIG. 5 (b) shows a case where editing is performed at an angle. In the conventional PCM recording / reproducing apparatus, editing processing is not performed. However, in the PCM recording / reproducing apparatus of the present invention, editing detection is performed as shown in FIG. A signal is output and editing processing is performed.

In the above embodiment, the error correction coding is performed on the block address. However, the coding is simplified, and the PC incorporating only the correction circuit that makes good use of the continuity of the block address is used.
The same effect can be obtained with the M recording / reproducing apparatus.

When the number of bits of the block address cannot be increased, the edit detection accuracy can be improved by using the block address in combination with the edit detection circuit of the conventional PCM recording / reproducing apparatus.

Here, hand-cut editing has been mainly described, but the present invention is also effective for simple electronic editing in which recording is switched from the middle of reproduction to editing.

〔The invention's effect〕

As described above, according to the present invention, for each block,
A block address encoded with an error correction code is provided, and a truncated edit point is detected from a discontinuous point of the block address, so that highly reliable editing processing can be performed.
In addition, there is an effect that a PCM recording / reproducing apparatus which can cope with the diagonal hand-cut editing can be obtained.

Further, according to the present invention, since no special track is provided for recording the block address, it is not necessary to reduce the track width of the original data recording. Therefore, it is irrelevant to a decrease in recording / reproduction quality due to a decrease in signal reproduction level expected when the track width is reduced.

In particular, in the case where the control track is provided as described above, if clogging occurs in the head for reproducing the control track, the discontinuity point cannot be detected because the control track cannot be reproduced. Even if clogging occurs in a track, reproduction of a block address or detection of a discontinuity can be performed by error correction, and the reliability is high.

[Brief description of the drawings]

FIG. 1 is a track pattern diagram showing a recording format of a PCM recording / reproducing apparatus according to one embodiment of the present invention. FIG. 2 is a conceptual diagram showing a block address recording format according to an embodiment of the present invention. FIG. 3 is a block diagram showing a PCM recording / reproducing apparatus according to one embodiment of the present invention. FIG. 4 is a schematic diagram of an edit detection circuit according to one embodiment of the present invention.
FIG. 5 is a waveform diagram showing an edit detection signal waveform in the case where the vicinity of the hand-cut edit point is reproduced in the PCM recording / reproducing apparatus according to one embodiment of the present invention, and in the case where the magnetic tape is reproduced in the diagonal cut edit. FIG. 6 is a track pattern diagram showing a conventional recording format. FIG. 7 is a track pattern diagram showing interleaving of PCM signals. Figure 8 shows a conventional PCM
FIG. 2 is a block diagram showing a recording / reproducing device. FIG. 9 is a conceptual diagram showing the flow of signals in the editing processing circuit. Figure 10 shows a conventional PCM
FIG. 4 is a waveform diagram showing an edit detection signal waveform when a vicinity of a hand-cut edit point is reproduced in the recording / reproducing apparatus. Figure 11 shows a conventional PCM
FIG. 9 is a waveform diagram showing an edit detection signal waveform when the editing is performed diagonally in the recording / reproducing apparatus. (1) is a magnetic tape, (2) to (9) are recording tracks,
(15) is an R encoding circuit, (16) is a block address generator, (23) is an R code decoding circuit, (24) is an edit detection circuit, and (28) is an edit processing circuit. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (2)

(57) [Claims] A digital data of one or a plurality of channels is distributed as a frame configuration in which a synchronization signal is added to a plurality of tracks arranged in a tape width direction, and a frame of a plurality of tracks is recorded as one block and reproduced. A second encoding means for adding an error correction code in the tape width direction to the input one block of digital data; and interleaving the digital data encoded by the second encoding means. Interleaving means for applying an error check code in the tape longitudinal direction to the interleaved digital data, and means for adding a block address continuous in block units in the tape width direction in each block. And a block address added by the encoding means and the first and second encoding means. Recording means for modulating and recording one block of digital data; demodulating means for demodulating digital data reproduced from a magnetic tape; first decoding means for decoding the demodulated digital data based on an error check code; De-interleaving means for performing de-interleaving processing on digital data, second decoding means for decoding the de-interleaved digital data based on an error correction code, and digital data decoded by the first decoding means. Edit detection means for extracting a block address and determining a discontinuity of the block address at a predetermined interval or more as an edit point; and when the edit detection means detects an edit point, the digital data in the vicinity of the edit point A PCM recording / reproducing apparatus, comprising: an editing processing means for performing an editing process. 2. Interleaved digital data of one or more channels is distributed as a frame configuration in which a synchronization signal is added to a plurality of tracks arranged in the tape width direction, and a frame of a plurality of tracks is recorded as one block. The recorded digital data of one block has an error check code added in the longitudinal direction of the tape and an error correction code added in the tape width direction, and a block address continuous in block units is written in the tape width direction in each block. Reproduce digital data from attached magnetic tape
In the PCM reproducing apparatus, a demodulating means for demodulating digital data reproduced from the magnetic tape, a first decoding means for decoding the demodulated digital data based on an error check code, and performing a de-interleaving process on the decoded digital data Deinterleaving means; second decoding means for decoding the deinterleaved digital data based on the error correction code; and extracting a block address from the digital data decoded by the first decoding means. Edit detection means for determining a discontinuity at a predetermined interval or more of an address as an edit point; and edit processing means for editing digital data near the edit point when the edit detection means detects the edit point. A PCM playback device, comprising: