JP2586775B2 - Digital signal recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital signal recording / reproducing apparatus for recording and reproducing digital signals on a tape recording medium, such as a digital video tape recorder (DVTR).

[0002]

2. Description of the Related Art In a conventional digital signal recording / reproducing apparatus, a recording signal is recorded by being divided into many synchronous code blocks. A synchronization code is added to each synchronization code block to identify the start position of the block. Further, following the synchronization code, when performing special playback such as slow and fast forward, in order to specify the content of the playback synchronization code block, information such as the channel number of the signal and the position on the screen, A content identification code (hereinafter, abbreviated as ID code or ID) is added to the signal and recorded. As a countermeasure against a code error when reproducing the ID code,
There has been a digital signal recording / reproducing apparatus which generates and records parity for an ID code (for example, Eto, Mita, Doi: Digital Video Recording Technology, Nikkan Kogyo Shimbun, 14
5, p. 1990).

In the above digital signal recording / reproducing apparatus, a synchronous protection circuit such as so-called forward protection and backward protection can be used in order to prevent detection of a synchronization code at the time of reproduction (for example, Tanaka: Digital Communication Technology). , Tokai University Press, pp. 74-82, 1986
Year). By using the synchronization protection circuit, it is possible to enhance a code error at the time of reproduction without adding a parity to the synchronization code.

[0004]

However, the above I
In a configuration in which a D code is added to a signal and recorded, the ID
If a code error occurs during code reproduction, all reproduced signals corresponding to the incorrect ID code become erroneous data. Further, if parity is added to the ID code for the purpose of avoiding this, the amount of the parity increases, so that the data rate of the actual recording signal becomes higher than the input signal to be originally recorded and reproduced.

The present invention has been made in view of the above problems, and has been described in connection with
It is an object of the present invention to provide a digital signal recording / reproducing apparatus which protects by estimating an ID code to be reproduced next by utilizing the periodicity of the code and protects the ID code without adding a parity to reduce a code error of the ID code. I have.

Further, it is an object of the present invention to provide a digital signal recording / reproducing apparatus in which an ID code estimation error is reduced during special reproduction by switching an ID code estimation algorithm in accordance with tape speed information from a tape running control section. The purpose is.

A digital signal recording / reproducing apparatus in which the ID code protection parameter is switched in response to the tape speed information from the tape running control unit, thereby improving the effect of reducing ID code error during special reproduction. It is intended to provide.

[0008]

SUMMARY OF THE INVENTION The present invention is to achieve the above object, the input digital signal, multiplexes the ID code at a given time, and outputs as a recording signal, and the predetermined
ID code adding means for outputting a timing signal indicating the time, recording / reproducing means for recording and reproducing a recording signal on a recording medium, and an ID code recorded at a predetermined position on the recording medium using the timing signal. Recording position controlling means for controlling the recording and reproducing means, a reproducing position controlling means for controlling the recording and reproducing means so that the ID code is reproduced at a predetermined time, and a reproducing signal outputted from the recording and reproducing means. To ID
Using the fact that the ID code is reproduced at a predetermined time while detecting the code, the ID code to be reproduced next is estimated, and the estimated ID code and the ID that is actually reproduced next are used.
According to the result of comparing the codes, the ID code is recorded from the reproduction signal using the ID code detecting means for applying at least one of the forward protection and the rear protection to the ID code and outputting the ID code, and using the ID code output from the ID code detecting means. ; and a reproduction signal processing means for restoring the digital signal, the content identification code
The detecting means estimates the content identification code to be reproduced next
During special playback, the algorithm estimated based on the playback speed
It is configured to change the rhythm .

[0009]

[0010] In the special reproduction, a content identification code detecting means for changing a parameter for performing at least one of front protection and rear protection in accordance with the reproduction speed is provided.

Preferably, the apparatus further comprises a content identification code detecting means for estimating a plurality of content identification codes corresponding to all the tracks scanned by the recording / reproducing means in accordance with the reproduction speed during the special reproduction. It is.

[0012] Further, there is provided recording position control means for controlling the recording / reproducing means so that the content identification code is recorded side by side on an adjacent track at the time of recording. Using the fact that the content identification code is recorded side by side on an adjacent track,
A content identification code detecting means for estimating a content identification code to be reproduced next is provided.

Preferably, a recording / reproducing means for performing recording / reproduction with a plurality of magnetic heads having different azimuths by using a magnetic recording medium as a recording medium, and a magnetic head for scanning by a magnetic head according to a reproduction speed at the time of special reproduction. A content identification code detecting means for estimating a plurality of content identification codes corresponding to each azimuth track is provided.

[0014]

According to the present invention, protection is performed by utilizing the periodicity of the ID code at the time of reproduction and estimating the ID code to be reproduced next by the above-described configuration.
Code errors of the D code can be reduced. Further, in correspondence with the tape speed information from the tape running control unit, the ID
By switching the code estimation algorithm, it is possible to reduce the code error of the ID code during trick play.

By switching the protection parameter of the ID code according to the tape speed information from the tape running control unit, the effect of reducing the code error of the ID code at the time of special reproduction can be improved.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A digital signal recording / reproducing apparatus according to one embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a digital signal recording / reproducing apparatus according to a first embodiment of the present invention. In this embodiment, a digital video signal is input to the recording signal generating means 2 through the input terminal 1. The recording signal generating means 2 converts the input digital video signal into a signal suitable for recording, adds an ID code, and outputs it as a recording signal. Further, the recording signal generating means 2 outputs a timing signal for recording the recording signal at a predetermined position of the recording medium 7 to the recording position control means 4.

The recording signal output from the recording signal generating means 2 is recorded on a magnetic recording medium 7 via a recording head 6 by a magnetic recording / reproducing means 5. At this time, the recording position control means 4 controls the magnetic recording / reproducing means 5 so that the ID code is recorded at a predetermined position on the magnetic recording medium 7.

At the time of normal reproduction and special reproduction, the reproduction position control means 10 controls the magnetic recording / reproduction means 5 so that the reproduction head 8 starts scanning the track accurately from a predetermined position. Further, the reproduction position control means 10 inputs information on the tape feed speed at the time of reproduction to the synchronous ID detection means 11. The reproduction signal from the reproduction head 8 is converted into a digital signal by the equalization detection means 9, and then input to the synchronization ID detection means 11 and the video signal synthesis means 12.

The synchronous ID detecting means 11 detects the synchronous code, further detects and corrects the ID according to the information on the tape feed speed inputted from the reproducing position control means 10, and outputs the corrected value to the video signal synthesizing means. Input to 12. The video signal synthesizing unit 12 synthesizes the recorded digital video signal from the reproduced digital signal from the equalization detecting unit 9 using the ID value from the synchronous ID detecting unit 11 and outputs the synthesized digital video signal to the output terminal 13. .

FIG. 2 shows a first configuration example of the synchronization ID detecting means 11. FIG. 3 shows an operation algorithm of the synchronization ID detecting means in FIG. Hereinafter, the operation algorithm of FIG. 3 will be described based on FIG. The reproduced signal output from the equalization detection means 9 is input to the ID detection means 22 and the synchronization code detection means 31 through the input terminal 20. The synchronization code detecting means 31 outputs an ID position pulse indicating the timing at which the ID is input. Each time the ID position pulse is output, the operation algorithm of FIG. 3 is executed for one loop.

First, it is assumed that the ID detecting means 22 and the ID estimating means 23 are in the initialization mode, and the output of the flip-flop 28 indicates a loss of synchronization. At this time, the ID detected by the ID detecting means 22 from the reproduced signal is output to the output terminal 30 and also input to the ID estimating means 23. The ID estimating means 23 is input from the reproduction position control means 10 through the input terminal 21.
The next ID is estimated and output using the input detection ID according to the information of the tape feed speed at the time of reproduction. After performing the above operation, the ID detecting means 22 and the ID estimating means 2
3 is the protection mode.

When the next ID is input, the ID detecting means 22 determines the estimated ID input from the ID estimating means 23,
The detected IDs are compared. When the estimated ID is equal to the detection ID, the ID detection unit 22 outputs a pulse to the gate 24. The non-coincidence counter 26 is cleared by the pulse passing through the gate 24, and the coincidence counter 27 is counted up. The coincidence counter 27 outputs a reset pulse to the flip-flop 28 when the value of the counter exceeds a predetermined value N1. Due to the reset pulse, the output of the flip-flop 28 indicates that synchronization is normal.

If the estimated ID and the detection ID are different, I
The D detection means 22 outputs a pulse to the gate 25. The coincidence counter 27 is cleared by the pulse passing through the gate 25, and the non-coincidence counter 26 is counted up. The non-coincidence counter 26 has a counter value of a predetermined value N
If it becomes 2 or more, the set pulse is output to the flip-flop 2
8. Output to the ID detecting means 22 and the ID estimating means 23. Due to the set pulse, the output of the flip-flop 28 indicates a loss of synchronization, and the ID detection unit 22 and the ID estimation unit 23 enter the initialization mode.

The switching means 29 includes a flip-flop 2
When the output of No. 8 indicates out of synchronization, the detection ID
Is output to the output terminal 30 when the output of the flip-flop 28 indicates that the synchronization is normal.

Next, an example of the operation of the ID estimating means 23 will be described. FIG. 4 shows an example of an arrangement of recording signals on the magnetic recording medium 7. FIG. 4 shows a case where a signal is recorded on a so-called helical scanning tape recorder and normal reproduction is performed. The oblique area separated by the solid line is the video signal track 41. FIG. 4 illustrates a case where the video signal track 41 is divided into 17 synchronous code blocks per track, as divided by a broken line. Further, in this embodiment, as indicated by CH1 and CH2 in FIG.
It is assumed that so-called azimuth recording is performed on a recording signal divided into channels. As described in each synchronous code block, a number indicating the number of the synchronous code block in the track is recorded in the ID code. In normal reproduction, all recorded signals are reproduced in order. Therefore, the ID estimating means 23 may add 1 to the value of the current ID to obtain the estimated ID.

FIG. 5 shows an example of a head scanning trajectory when performing special reproduction. In the case of the trick play, the head plays across the tracks, so that a simple guess as in the normal play cannot be made. However, a certain pattern exists in the order in which the recording signals are reproduced according to the tape feed speed. In the example of FIG. 5, it is assumed that the tape feed speed of the special reproduction is +4 times that of the normal reproduction.

According to the scanning trajectory of FIG. 5, the reproduced signal from the head is as shown in FIG. Here, assuming two-channel azimuth recording, channel 1
Channel 2 (CH2) with head (abbreviated as CH1)
Cannot be reproduced. Also, I
Assuming that the D code is recorded at the lower end of each synchronous code block, the read pattern of the ID code is as shown in FIG.
become that way.

With respect to this reproduction pattern, ID estimation means 2
6 has, for example, as shown in FIG. 6C, two counters corresponding to two CH1 tracks scanned by the head, and both IDs of the two counters are estimated IDs.
Is output to the ID detecting means 22. ID detecting means 2
For 2, it suffices to select one that matches the detection ID from the two estimated IDs.

Note that the ID estimating means 23 does not necessarily need to use two counters. For example, instead of the counter 2, a circuit that always outputs the value of the counter 1 plus 2 may be used.

The ID protection at the time of special reproduction described here is as follows.
This can be easily performed by recording the synchronization code and the ID side by side in adjacent tracks. If the synchronization code and the ID are not recorded side by side in the adjacent tracks, the cycle of the reproduction of the synchronization code and the ID when the tracks are crossed is shifted, so that the processing becomes complicated.

As described above, in the first embodiment,
During reproduction, the periodicity of the ID code is used, and the next reproduced I
It is possible to protect by estimating the D code, and to reduce the code error of the ID code without adding parity. Further, by switching the estimation algorithm of the ID code in accordance with the tape speed information from the tape running control unit, it is possible to reduce the code error of the ID code at the time of special reproduction.

In the first embodiment, two-channel azimuth recording is assumed. However, the same effect can be obtained by the same configuration with an arbitrary number of channels. When azimuth recording is not performed, the effect is reduced due to interference between adjacent tracks, but a code error of the ID code can be reduced by using the same configuration.

Next, a second embodiment of the present invention will be described. The difference from the first embodiment lies in the configuration of the synchronization ID detecting means 11.

FIG. 7 shows a second example of the configuration of the synchronization ID detecting means 11. The difference from the configuration of FIG. 2 is that information on the tape feed speed at the time of reproduction, which is input from the reproduction position control means 10 through the input terminal 21, is input to the mismatch counter 26 and the match counter 27.

As shown in FIG. 6B, during the special reproduction, a case occurs where the detected ID and the estimated ID are almost certainly different. Therefore, in the parameter N1 of the coincidence counter and the parameter N2 of the non-coincidence counter shown in FIG. 3 and described in the first embodiment, the values in which the ID error is reduced most are different from those in the normal reproduction.
In particular, in general, the optimum value in the special reproduction of N2 is larger than the optimum value in the normal reproduction. Therefore, by changing the values of the parameters N1 and N2 according to the tape feed speed by the configuration of FIG. 7, the effect of reducing the code error of the ID code at the time of special reproduction can be improved.

In the first and second embodiments, the case where digital signals are recorded on a magnetic recording medium has been described. However, the recording medium is not limited to magnetic recording. You may. In the first and second embodiments, the case where a digital video signal is input has been described.
Similar effects can be obtained even when other signals such as digital data of a computer are input.

[0038]

As described above, according to the present invention, protection is performed by using the periodicity of an ID code at the time of reproduction and the ID code to be reproduced next is estimated, and parity is added. Therefore, it is possible to reduce the code error of the ID code. Further, by switching the estimation algorithm of the ID code in accordance with the tape speed information from the tape running control unit, it is possible to reduce the code error of the ID code during the special reproduction.

Further, by switching the protection parameter of the ID code according to the tape speed information from the tape running control unit, the effect of reducing the code error of the ID code at the time of special reproduction can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of a digital signal recording / reproducing apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a first configuration example of a synchronization ID detection unit 11;

FIG. 3 is a diagram showing an operation algorithm of a synchronization ID detection unit 11;

FIG. 4 is a pattern diagram showing an example of an arrangement of recording signals on a magnetic recording medium 7;

FIG. 5 is a pattern diagram showing an example of a head scanning locus when performing special reproduction.

6A is a diagram showing a reproduced signal from a head. FIG. 6B is a diagram showing a pattern from which an ID code is read. FIG. 6C is a diagram showing values of two counters in the ID estimating means 23.

FIG. 7 is a diagram showing a configuration example of a synchronization ID detection unit 11 according to a second embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 input terminal 2 recording signal generating means 4 recording position controlling means 5 magnetic recording / reproducing means 6 recording head 7 magnetic recording medium 8 reproducing head 9 equalizing detecting means 10 reproducing position controlling means 11 synchronous ID detecting means 12 video signal synthesizing means 13 output Terminal 20 Input terminal 21 Input terminal 22 ID detecting means 23 ID estimating means 24 AND gate 25 AND gate 26 Mismatch counter 27 Match counter 28 Flip-flop 29 Selection means 30 Output terminal 31 Synchronous signal detection circuit 41 Video signal track

Claims (5)

(57) [Claims] 1. A content identification code adding means for multiplexing an input digital signal with a content identification code at a predetermined time, outputting the multiplexed signal as a recording signal, and outputting a timing signal indicating the predetermined time; Is recorded on a recording medium,
Recording / reproducing means for reproducing, recording position control means for controlling the recording / reproducing means so that the content identification code is recorded at a predetermined position on the recording medium using the timing signal, and the content identification code A playback position control means for controlling the recording and playback means so that the content identification code is played back at a predetermined time, a content identification code is detected from a playback signal output from the recording and playback means, and the content identification code is The content identification code to be reproduced next is estimated using the reproduction at the time, and the content identification code is estimated based on the result of comparing the estimated content identification code with the actually reproduced content identification code. Recording from the reproduction signal using a content identification code detecting means for performing at least one of forward protection and rear protection on the content identification code and outputting the content identification code output from the content identification code detecting means. To restore the digital signal that has been provided with a reproduction signal processing means, the content identification code detection
Output means for estimating the content identification code to be reproduced next
In special playback, the algorithm is estimated according to the playback speed.
A digital signal recording / reproducing apparatus, wherein the digital signal recording / reproducing apparatus is configured to change the dynamics. 2. A device according to claim 1 , further comprising a content identification code detecting means for changing a parameter for performing at least one of forward protection and backward protection in accordance with the playback speed during special playback.
Item 2. A digital signal recording / reproducing apparatus according to Item 1 . To 3. During special reproduction, in accordance with the reproduction speed, corresponding to each of all the tracks to be scanned in said recording means, including a content identification code detection <br/> detecting means for estimating a plurality of content identification code 3. The digital signal recording / reproducing apparatus according to claim 1, wherein 4. A recording position control means for controlling said recording / reproducing means so that said content identification code is recorded side by side on an adjacent track at the time of recording, and said content at a special reproduction time in accordance with a reproduction speed. 3. The digital signal recording / reproducing apparatus according to claim 1 , further comprising: content identification code detecting means for estimating a content identification code to be reproduced next using the fact that the identification codes are recorded side by side on adjacent tracks. apparatus. 5. A magnetic recording medium as a recording medium,
A recording / reproducing means for recording / reproducing with a plurality of magnetic heads having different azimuths, and a content for estimating a plurality of content identification codes corresponding to respective tracks of the same azimuth scanned by the magnetic head according to the reproducing speed at the time of special reproduction. digital signal recording and reproducing apparatus according to any one of claims 1 to 4 comprising an identification code <br/> detecting means.