JPS63108571A - Recording and reproducing device - Google Patents

Abstract

PURPOSE:To improve an error correction capability and to detect a separation edition with high accuracy by providing a Q code decoding means high in the error correction capability and a Q code decoding means high in an error detection capability and switching and using. CONSTITUTION:A signal read by a reproducing head 2 from a magnetic tape 1 is converted into a PCM signal in a demodulation circuit 3, the error is detected in a P code check circuit 4 and inputted to a signal selector 7 through an interleave circuit 5, a track synthesizing circuit 6. In an ordinary reproduction, the selectors 7, 10 select a first code decoding means 8 high in the error correction capability and directly output to an editing processing circuit 11. When there is a part to be separated and edited, the selectors 7, 10 are switched by the control signal of a first edited point detection circuit 14, a correction incapability is effectively detected by a second Q code decoding means 9 high in the error detection capability and an editing processing is carried out in the circuit 11 through a second edited point detection circuit 15. Accordingly, the error correction and the separation editing detection are performed with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a recording/reproducing apparatus for reproducing a magnetic tape on which an encoded pulse code modulation signal is recorded.

[Conventional technology]

FIG. 3 is a diagram showing a recording format of a conventional pulse code modulation type recording and reproducing apparatus disclosed in, for example, Japanese Patent Laid-Open No. 56-37870.

1 is a magnetic tape, and 16 to 23 are recording tracks. Let Dn be a pulse code modulation (hereinafter referred to as PCM) signal sequence that is analog-to-digital converted and arranged in time,
This PCM signal train Dn is delayed by several blocks (2 units in the figure) for each track and arranged in the arrangement shown in the figure. In recording track 16, DI, D7. ...D87
An error check code (shortened cyclic code CC is often used) P is added to K, and a synchronization signal S is added to form a frame. Recording tracks 17 to 21 also have a similar configuration. Further, in the recording track 22, an error check code P is added to check symbols Ql, Qa l...Q18 of an error correction code (for example, a Reed-Solomon code) added to a predetermined PCM signal sequence, A synchronization signal S is added to form a frame. The recording track 23 is also similar to the recording track 22. Further, a collection of frames of recording tracks 16 to 23 is called a block.

Next, FIG. 4 clearly shows the arrangement of the PCM signal and the arrangement of the check symbols Q of the correction code.

As described above, the PCM signal sequences Dn arranged in time are arranged several blocks apart as shown in the figure. This is called interleaving, and has the function of dispersing errors caused by scratches or defects on the tape. As I will say later,
PCM signal before editing and PCM signal after editing near the editing point
The data before editing is created in a certain period 2jIL using a correction means, and the data before editing is faded out, and the data after the editing point is faded in to perform a crossfade, and the signals before and after the editing point can be smoothly connected. There are also other functions.

FIG. 5 is a schematic block diagram of a conventional pulse code modulation recording and reproducing apparatus. In the figure, 24 is an analog signal input terminal, and 25 is an analog/digital converter (hereinafter referred to as A/D converter).
26 is an error correction encoding circuit (hereinafter referred to as a D converter), 26 is an error correction encoding circuit (hereinafter referred to as
(referred to as Q encoding circuit), 27 is a track distribution circuit, 28
is an interleave circuit, 29 is an error check coding circuit (hereinafter referred to as a P coding circuit), and 30 is a modified frequency (MFM) for recording a PCM signal.
modulation circuit, such as
31 is a recording head, 2 is a playback head, 3 is a demodulation circuit that demodulates the output reproduced by the playback head into a PCM signal, 4
5 is a P code check circuit that checks the error check code (hereinafter referred to as P code) in the reproduced PCM signal; 5 is a de-interleague circuit that restores the track-delayed data; 6
32 is a track synthesis circuit that arranges multi-track PCM signals into a time-series signal, and 32 is an error correction code (hereinafter referred to as Q code).
14 is a first edit point detection circuit that detects edit points based on the detection results of the P code check circuit 4; 15 is a Q code decoding circuit that detects edit points based on the results of the Q code decoding circuit; A second edit point detection circuit 11 detects the first edit point. Second
Editing point detection circuit 14. An editing processing circuit connects the PCM signal near the editing point without a level jump according to the control signal from 15, and 12 is a digital-to-analog converter (hereinafter referred to as D).
/A converter), 13 is an analog signal output terminal.

Next, the operation of such a recording/reproducing apparatus will be explained.

The analog signal input from the input terminal 24 is converted into a PCM signal by the A/D converter 25.

In the Q encoding circuit 26, a check symbol Q is added to this PCM (number 3 sequence Dn).The trunk distribution circuit 27 and the interleaving circuit 28 convert the PCM signal as shown in FIGS. Furthermore, a P code is added to each track in the P encoding circuit 29, and the VCfilr 1st period signal S is also added and sent to the modulation circuit 30.The modulation circuit 30 converts the signals recordable on the magnetic tape is modulated and recorded on the magnetic tape 1 via the recording head 31.

Next, the operation on the playback side will be explained. The signal read out by the playback head 2 is converted into a PCM signal by the demodulation circuit 3, error detected by the P code check circuit 4, passed through the deinterleaving circuit 5, the trunk synthesis circuit 6, and then the Q code decoding circuit 32. By performing error υ detection and error correction, the time series P
It becomes a CM signal.

When performing normal playback without hand-cutting editing parts, the PCM f4 output from the Q code decoding circuit 32 is output as is from the editing processing circuit 11, and the PCM f4 is output from the D/A converter 12.
The signal is converted into an analog signal and outputted from the analog signal output terminal 13. In the case of playing back a magnetic tape 1 that has been manually cut and edited, errors are concentrated at the same position in the vertical direction of multiple recording tracks because vertical cutting is performed at the editing point. The control output of the first edit point detection circuit 14 using the sign check result is
It is sent to the editing processing circuit 11. On the other hand, as for the Q code, it is added to the PCM signal that has been subjected to track delay as shown in Figure 4, so if there are 9 edit points in the code, the code will not be coherent before and after the edit point. The control output of the second editing point detection circuit 15, which focuses on the fact that the two do not match, is similarly sent to the editing processing circuit 11. Edit processing circuit 1
1, editing processing is executed by control signals from both the first editing point detection circuit 14 and the second editing point detection circuit 15 according to the flowchart of FIG. 6, which will be explained later. The output of the editing processing circuit 11 is converted into analog data by a D/A converter 12 and output from an analog signal output terminal 13.

FIG. 6 shows a flowchart for hand-cutting editing determination. First, the control signal which is the first edit point detection signal from the first edit point detection circuit 14 is checked (step Is), and it is determined whether the control signal is detected or not (step S2). If detected, the following steps are performed: The process moves on to checking the control signal which is the second edit point detection signal from the second edit point detection circuit 15 (step 38), and if it is not detected, the control signal from the first edit point detection circuit 14 is checked again. return. On the other hand, after the process in step 3S, it is determined whether or not a control signal from the second editing point detection circuit 15 is detected (step 4S), and if detected, the editing process is executed (step 5S). If it is not detected, the process returns to the start and checks the control signal from the first edit point detection circuit 14.

Near the hand-cut editing point, the PCM signal is delayed between recording tracks, so near the editing point, the pre-edited PCM signal and the edited PCM signal are doubled using a correction means for a certain period of time. Is possible. Figure WJ7 shows the playback signal before and after the hand-cut editing point. If the left side of the editing point is tape A and the right side is tape B as shown in Figure 7(a), the playback signal of this tape will produce an overlapping section of j blocks as shown in Figure 7(b). be able to. By fading out the A tape playback signal and fading the B tape playback signal in, crossfading can be performed and level jumps in the playback signal can be prevented.

The crossfade interval j is usually related to the interleague length,
In the interleaving shown in FIG. 4, the relationship 32>j holds true.

[Problem that the invention seeks to solve]

Since the conventional recording and reproducing apparatus is configured as described above, the Q code decoding circuit 32 has a function of correcting errors caused by recording and reproducing the magnetic tape 1, and a function of correcting the code consistency around the editing point of the hand stamp 9. (cannot be corrected)
It is necessary to have a function to detect In the former case, it is necessary to make the most of the code's ability to perform error correction, and in the latter case, it is also necessary to reliably detect non-correctability.Decoding algorithms must be developed to meet the former requirement. If this algorithm is adopted, it may not be possible to detect that the code that cannot be corrected spans over the editing points, resulting in erroneous corrections.On the other hand, if the Begu decoding algorithm that satisfies the latter requirement is adopted, corrections may be made. Although error detection can be reliably performed, there are problems such as a decrease in error correction ability and a problem with normal playback.

This invention was made in order to solve the above-mentioned problems, and provides a recording and reproducing apparatus that can perform error correction to the maximum of the code's ability during reproduction, and can also reliably detect editing. The purpose is to obtain.

[Means for solving problems]

The recording and reproducing apparatus according to the present invention includes a first error correction decoding means having a high error correction ability and a second error correction decoding means having a high error detection ability, and one of these means includes an error code check circuit. Based on the output of the above, the first edit point detection circuit inputs the digital data, and further, based on the uncorrectable output of the second error correction decoding means, the second edit point detection circuit inputs the digital data. The configuration is such that the data is sent to an editing processing circuit that performs smooth continuous processing before and after the editing point.

[For production]

The first edit point detection circuit in the present invention detects a hand-cut edit point from the output of the error code check circuit, and switches input of the digital data from the first error correction combination means to the second error correction decoding means, If the error detected by the second edit point detection circuit extends over a predetermined number of cycles, the digital data is faded in and out before and after the edit point in the edit processing circuit without changing the overall level. It operates to edit smoothly continuous digital data.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, 7.10 is a signal selector, 8 is a first Q code decoding means with high error correction ability, and 9 is a second Q code decoding means with high error detection ability. Note that other blocks that are the same as those shown in FIG. 5 are given the same reference numerals, and redundant explanation thereof will be omitted.

Next, one operation will be explained. A signal read out from the magnetic tape 1 by the reproducing head 2 is converted into a PCM signal by a demodulation circuit 3, and an error is detected by a P code check circuit 4.

Furthermore, a de-increase circuit 5, a track synthesis circuit 6
The first Q code decoding means 8 or the second Q code decoding means 9 selected by the linked signal selector 7.10
Error detection and error correction are performed on the signal, resulting in a time-series PCM signal.

When performing normal playback without hand-cut editing, the signal selector 7.10 selects the first Q code decoding means 8, which has a high error correction ability, and performs correction to the fullest of the code's ability. The output PCM signal is sent to the editing processing circuit 11
The signal is outputted as it is, converted into an analog signal by the D/A converter 12, and outputted from the analog output terminal 13.

In the case of reproducing a magnetic tape 1 that has been edited by hand, the signal selector 7 and 10 are switched by a control signal from the first edit point detection circuit 14 using the P code check result.
The second Q code decoding means 9 having a high false 9 detection ability is selected. Since this second Q code decoding means 9 has a high ability to detect errors, when a hand-cut edit point exists in the code, it detects that the code becomes inconsistent before and after the edit point.

In other words, it is possible to reliably detect the uncorrectable state. Then, the second editing point detection circuit 15 determines whether or not the uncorrectable area extends over several blocks. If the uncorrectable area extends over several blocks, editing is performed, and a control signal is sent to the editing processing circuit 11. The editing processing circuit 11 executes editing processing in response to a control signal from the second editing point detection circuit 15. The output of the editing processing circuit 11 is converted into analog data by the D/A converter 12 and output from the analog output terminal 13.

FIG. 2 shows a flowchart of the above-mentioned hand stamp editing discrimination process. According to this, first, the control signal, which is the first edit point detection signal from the first edit point detection circuit 14, is checked (step 11S), and it is determined whether the control signal is detected (step l28), and if detected. , the switch is made to the second Q code decoding means 9 (step 138), and if no detection is detected, the first Q code decoding means 8 remains and the control signal from the first edit point detection circuit 14 is once again output. Return to check (step 148). On the other hand, the second Q code decoding means 9 operates, checks the control signal from the second edit point detection circuit 15 (step 15S), and determines whether or not the control signal is detected (step 168). starts the editing process (step 178), and if it is not detected, returns to the start and receives the control from the first edit point detection circuit 14? @ Check the signal.

Note that the first editing point detection circuit 14 controls! 1 signal detected,
Despite the K selected by the second Q code decoding means 9,
If the second editing point detection circuit 15 determines that no control signal is detected, the error correction performance will be low although no editing processing will be performed and normal playback will occur; however, the editing will occur in an instant. , it is not a problem judging from the overall proportion.

In the above embodiment, two types of decoding circuits, the first Q code decoding means 8 and the second Q code decoding means 9, were used.
When using a program-controlled decoding circuit, the amount of hardware can be reduced by switching between a decoding algorithm program with high error correction capability and a decoding algorithm program with high error detection capability. The structure is the same (one type of decoding circuit is used), and the same effect as in the above embodiment is achieved.

〔Effect of the invention〕

As described above, according to the present invention, the Q code decoding circuit with high error correction ability and the Q code decoding circuit with high error detection ability are provided separately, and the control signal of the first editing point detection circuit is Since one of these is configured to be switched and used, the editing process can be properly performed when necessary, the error correction ability is high, and the hand-cut editing detection can be performed with high accuracy.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the playback side of a recording/playback device according to an embodiment of the present invention, FIG. 2 is a flowchart showing hand-cut editing discrimination processing according to an embodiment of the present invention, and FIG. 3 is a conventional recording format. FIG. 4 is a track pattern diagram showing conventional interleaving of PCM signals, FIG. 5 is a block diagram showing a conventional recording/reproducing device, and FIG. 6 is a flowchart showing conventional hand-cut editing discrimination processing. , FIG. 7 is an explanatory diagram showing the cross-fade relationship of signals in a conventional editing processing circuit. 1 is a magnetic tape, 4 is a P code check circuit, 7°10 is a signal selector, 8 is a first Q code decoding means, 9 is a second
11 is an editing processing circuit, 14 is a first editing point detection circuit, 15 is a second editing point detection circuit, 16 to 23
is a recording track. In addition, in the figures, the same reference numerals indicate the same or equivalent parts. Patent applicant Mitsubishi Electric Corporation (2 others) Figure 2 Figure 5 Figure 25: A/D hard cup Figure 6

Claims (3)

[Claims] (1) After adding an error correction code to the digital data to be recorded, it is distributed over multiple recording tracks and interleaved, and an error check code is added to each recording track to the interleaved digital data to generate magnetic data. On the other hand, after reproducing the recorded digital data, the error check code is checked by an error code check circuit, de-interleaved is performed, the digital data of each recording track is synthesized, and the error correction code is decoded. In a recording/reproducing apparatus in which a circuit performs error detection and error correction in a correction code, and when an error occurs, an editing processing circuit performs cross-fade processing on digital data at an editing point. high first
error correction code decoding means and a second device with high error detection ability.
and a first editing step of inputting the synthesized digital data to either the first error correction code decoding means or the second error correction code decoding means based on the output of the error correction code decoding means and the error code checking circuit. Based on the point detection circuit and the uncorrectable output of the second error correction decoding means,
A recording/reproducing apparatus comprising: a second editing point detection circuit for sending the synthesized digital data to the editing processing circuit. (2) The recording and reproducing apparatus according to claim 1, wherein the first editing point detection circuit detects errors that occur intensively at the same position in the vertical direction of a plurality of recording tracks. . (3) The recording and reproducing apparatus according to claim 1, wherein the second editing point detection circuit detects whether or not the uncorrectable output continues for a predetermined period.