JP2002325223A - Magnetic recording and reproduction device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device wherein a track width is narrow during insertion recording by a wide head and the switching of smooth scene is enabled without inserting data with a sense of incompatibility on a part of a video at the switching point of the scene even when the correction processing of the video is performed. SOLUTION: A track with narrowed width is detected based on the envelope level, correction information and modification information. When a track in which the width is narrowed is detected, output is changed over to a video signal of one frame stored in a one-frame storage circuit in place of the video signal with corrected error.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a digital magnetic recording / reproducing apparatus and a magnetic recording / reproducing method.

[0002]

2. Description of the Related Art First, a digital magnetic recording and reproducing apparatus
A general device example (hereinafter referred to as a digital VTR) will be described. FIG. 6 is a main block diagram showing a configuration of a recording system of the recording / reproducing apparatus. 6, reference numeral 601 denotes a video / audio signal processing circuit; 602, an error correction encoding circuit;
Reference numeral 3 denotes a recording encoding circuit, 604, a head, and 605, a magnetic recording medium. The video / audio signal processing circuit 601 converts the video signal and the audio signal instructed to be recorded into digital signals,
The recording data is generated by performing a predetermined process. The error correction coding circuit 602 adds an error correction code to the recording data (the error correction code will be described later). Recording encoding circuit 6
Numeral 03 modulates the recording data to which the error correction code has been added into a format corresponding to the recording format, and amplifies the recording data to a prescribed level. The recording data is recorded on the magnetic recording medium 605 by the head 604.

In general, in a digital VTR, the S / N
The error rate is deteriorated due to deterioration, envelope fluctuation, dropout, etc., and image data is lost, making it difficult to see. Therefore, a redundant portion is added as an error correction code at the time of recording, so that even if an error component is mixed at the time of reproduction, the original signal can be completely restored by the error correction code.

FIG. 5 is a main block diagram showing a configuration of a reproducing system of a conventional recording / reproducing apparatus. In FIG.
Denotes a magnetic recording medium, 502 denotes a head, 503 denotes a decoding circuit, 504 denotes an error correction circuit, 505 denotes an error correction circuit, and 506 denotes a video / audio signal processing circuit. Recorded data is reproduced from the magnetic recording medium 501 by the head 502. The decoding circuit 503 decodes a data signal from the reproduced recording signal. The error correction circuit 504 corrects an error of the reproduction signal based on the error correction code added at the time of recording and restores the original signal. When an error exceeding the correction limit of the error correction circuit 504 is mixed, a correction process is performed by the error correction circuit 505 (the correction process will be described later). The video / audio signal processing circuit 506 performs a predetermined process to convert a digital signal into an analog signal (video signal and audio signal).
Convert to

The correction process is a process of taking data from the same place of the previous frame and replacing it. In general, a video signal has a high correlation between the previous and next frames, and data at the same position in the previous frame rarely changes greatly.
Normally, even if the correction process is performed, the image is unlikely to cause a great sense of discomfort. In a VTR, an operation called insert recording or splicing is frequently performed. In a digital VTR, since one frame is composed of a plurality of tracks, insert recording or splicing must be performed for each of the plurality of tracks.

Next, an example of a method of insert recording in a digital VTR will be described. FIG. 2 is a track pattern diagram during insert recording in the recording / reproducing apparatus. In FIG. 2, one frame is composed of ten tracks n0 to n9, and a frame d is inserted at an insertion start point a.
Insert a new frame into
Suppose you end with Normally, when insert recording is performed, in order to ensure track continuity, the track is rewound once and then reproduced, and the frame c immediately before the insert recording is performed.
Of the last track n9 and stops at that position. This operation is called short play. Thereafter, according to the operation of starting the insertion, the recording of the first track n0 of the frame d to be inserted is started from the next position.

In this case, the digital VTR performs narrow track recording with a track width as narrow as possible in order to increase the recording density per unit area. However, recording is performed using a head slightly wider than the track width (hereinafter, referred to as a wide head) in order to allow a margin for tracking control during reproduction. As a tracking method in this case, for example, three types of tracking signals are superimposed on each track at the time of recording, and at the time of reproduction, these tracking signals are extracted as crosstalk components from adjacent tracks, and tracking control is performed according to the components. Do.

At this time, as the head width for picking up the crosstalk increases, the tracking signal level increases and the margin of the tracking control increases, but when the head width decreases, the signal level decreases and the tracking becomes difficult. Therefore, considering the stability of tracking, stable tracking can be performed when the head width is wider than the track width, and the wider the head width, the greater the margin for tracking. For this reason, a wide head that is slightly wider than the track width is usually used.

[0009]

In insert recording using a conventional wide head, track width may be discontinuous when insert recording is performed. FIG. 3 is a track pattern diagram showing a problem during insert recording in the recording / reproducing apparatus. In FIG. 3, one frame is represented by n
Suppose that a track is composed of ten tracks 0 to n9, a new frame is inserted into a frame d at an insertion start point a, and ends at an insert end point b. Normally, when insert recording is performed, in order to ensure track continuity, rewind once and then play back to perform insert recording.
The last track n9 of the previous frame c is searched and stopped at that position. This operation is called short play. Thereafter, according to the operation of starting the insertion, the recording of the first track n0 of the frame d to be inserted is started from the next position.

As described above, when a wide head is used,
The tracking is controlled so that the center of each track coincides with the center of the head during short play. Therefore, control is performed such that the center of the head comes to the track center f during the reproduction period of the frame c. In other words, the head position for recording the first track n0 of the frame d is determined by the short play, so that the head position for recording the first track n0 of the frame d is slightly shifted from the head position at the time of the original recording. Of the last track n9. That is, since a part of the last track n9 of the frame c is overwritten and erased, the width of the last track n9 of the frame c is narrower than other tracks.

Similarly, the head position for recording the last track n9 of the frame d covers a part of the first track n0 of the frame e immediately after the insert recording, and thus the first track n0 of the frame e. Is overwritten and erased, so that the first track n0 of the frame e is narrower than the other tracks. That is, the track width becomes narrower at the insert start point a and the insert end point b, and the reproduction envelope level becomes smaller.
The bit error rate deteriorates.

As described above, even if the bit error rate of a digital VTR is degraded and an error component is mixed in a reproduced signal, an error correction process is performed by an error correction circuit during reproduction to restore the original signal. Can be. However, when an error exceeding the correction limit is mixed, the error correction process cannot be performed and the correction process is performed. Generally, a video signal has a high correlation between the preceding and succeeding frames, and data at the same position in the previous frame is unlikely to change significantly. Therefore, even if the correction processing is performed, the image is unlikely to cause a great sense of discomfort. However, in the case of insert recording, the screen usually changes greatly and the correlation between the frames is low, so that the same track in the previous frame often has completely different video data.

For example, when the correction processing is performed at the insert end point b, the data of the first track n0 of the frame e is replaced with the data of the first track n0 of the frame d in which the insert recording is performed.
In this screen, a part of the image of frame d having no correlation is partially inserted. That is, the image of the frame recorded by insert recording is partially mixed in the next frame image, resulting in a very unsightly screen.

The present invention has been made in view of such a point, and when performing insert recording with a wide head, if the track width becomes narrow, the bit error rate deteriorates and even if the image correction processing is performed, uncomfortable feeling is obtained. It is an object of the present invention to provide a recording apparatus capable of switching scenes without any change.

[0015]

In order to solve the above-mentioned problems, the present invention has the following arrangement. The invention according to claim 1 is a digital magnetic recording / reproducing apparatus for converting a video signal and an audio signal into a digital signal and recording / reproducing the digital signal, wherein decoding means for decoding a reproduction signal detected from a magnetic recording medium, Error correcting means for correcting an error of the reproduced signal decoded by the decoding means based on an error correction code added at the time of recording to restore an original signal; and an error exceeding a correction limit of the error correcting means. Error correction means for performing a correction process on a reproduced signal having: one frame storage means for storing one frame of output signals of the error correction means; information on the error correction means or the error correction means or an envelope of the reproduced signal Output switching means for selectively outputting an output signal of the error correction means and an output signal of the one-frame storage means based on a level. A magnetic recording and reproducing apparatus.

According to a second aspect of the present invention, there is provided a digital magnetic recording / reproducing method for converting a video signal and an audio signal into a digital signal and recording / reproducing the digital signal, and decoding the reproduced signal detected from the magnetic recording medium. An error correcting step of correcting an error of the reproduced signal decoded by the decoding step based on an error correction code added at the time of recording to restore an original signal; and a correction limit of the error correcting step. Error correction step of performing a correction process on a reproduced signal having an error exceeding the limit, a one-frame storage step of storing one frame of the output signal of the error correction step, and information or reproduction of the error correction step or the error correction step. The output signal of the error correction step and the one-frame storage mode are determined based on the signal envelope level. An output switching step for selectively outputting the output signal of the-up, a magnetic recording and reproducing method comprising a.

According to the present invention, even when the track width becomes narrow at the time of insert recording by the wide head and the image correction processing is performed, unnatural data is inserted into a part of the image at the scene switching point. Thus, it is possible to provide a device that can smoothly switch scenes.

[0018]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention;

<< Embodiment >> FIG. 1 is a main block diagram showing a configuration of a reproducing system of a recording / reproducing apparatus according to Embodiment 1 of the present invention. In FIG. 1, 101 is a magnetic recording medium, 102 is a head, 103 is a decoding circuit, 104 is an error correction circuit,
05 is an error correction circuit, 106 is a one-frame storage circuit,
107 is an output switching circuit, and 108 is a video / audio signal processing circuit. Recorded data is reproduced from the magnetic recording medium 101 by the head 102. The decoding circuit 103 decodes a data signal from the reproduced recording signal. The error correction circuit 104 corrects an error of the reproduction signal based on the error correction code added at the time of recording and restores the original signal. When an error exceeding the correction limit of the error correction circuit 104 is mixed, the error correction circuit 105 performs a correction process of taking data from the same place of the previous frame and replacing it. One of the outputs of the error correction circuit 105 is output to the output switching circuit 107 as it is, and the other is output to the output switching circuit 107 via the one-frame storage circuit 106.

The one-frame storage circuit 106 stores one frame signal from the error correction circuit 105.
The output switching circuit 107 switches between the signal from the error correction circuit 105 and the signal from the one-frame storage circuit 106. Normally, the output switching circuit 107 is
Is output to the video / audio signal processing circuit 108.
However, the track width is narrowed by the insert recording, and the error correction circuit 104 detects an error in the entire track,
When the error correction circuit 105 detects an error exceeding the error correction limit, the output switching circuit 107 converts the signal from the one-frame storage circuit 106 into a video / audio signal processing circuit 108.
Switch to output. The signal output from the output switching circuit 107 is subjected to predetermined processing in a video / audio signal processing circuit 108, and is converted from a digital signal into an analog signal (video signal and audio signal).

As described above, in the frames before and after the insert recording, the wide head partially overwrites the track, so that the track width becomes narrower than other tracks. FIG. 4 shows a reproduction envelope level in each track when a frame on which insert recording is performed in the recording / reproducing apparatus is reproduced. The output level of the normal reproduction envelope changes according to the track width. However, as shown in FIG. 4, the last track n9 of the previous frame c in which the insert recording is performed is partially erased by the insert recording and the other track n9 is erased. The track width is narrower than that. Therefore, the output level of the envelope level i when this track is reproduced is lower than the envelope level h when the other track is reproduced. Similarly, since the track width of the first track n0 of the frame e immediately after the insert recording is also reduced, the output level of the reproduction envelope j is also reduced.

As the reproduction envelope becomes smaller, the bit error rate deteriorates. The error correction circuit 104 performs the correction processing, and it is necessary to further perform the correction processing by the error correction circuit 105 according to the degree of deterioration. At this time, the output switching circuit 107 becomes narrow based on the envelope level, the correction information (for example, bit error rate) in the error correction circuit 104, or the correction information (for example, sync information) in the error correction circuit 105. Detected track. When the track whose width has become narrower is detected, the output switching circuit 107 switches the output signal from the output signal of the error correction circuit 105 to the output signal of the one-frame storage circuit 106. Normally, when the track width becomes narrow and the bit error rate deteriorates and correction processing is performed,
Bring the data from the same location in the previous frame and modify it. Therefore, only the data of one narrowed track is replaced. If the correlation between the preceding and following frames is low, a part of the image of a frame having no correlation is inserted into the image of a certain frame, resulting in a very unsightly image.

However, according to the present invention, when it is detected that the track width has become narrow by detecting the reproduction signal envelope or the like, the data (part of the screen) of the track is not replaced, but the one-frame storage circuit 106 is used. Is replaced in units of one frame. As a result, the video of the previous frame is repeated for one frame,
Part of uncorrelated video is not inserted in the frame. That is, before and after the insert recording unit, the video of the previous frame is simply repeated for one frame. For this reason, a part of the frame video before the insert recording part is inserted into the frame video recorded by insert recording, or the video recorded by insert recording is partially mixed And no other video is inserted into the screen.
Therefore, it is possible to switch scenes very smoothly without feeling uncomfortable.

[0024]

As described above, according to the magnetic recording / reproducing apparatus of the present invention, a part of the track is overwritten when the insert recording is performed by the wide head, so that the track width is narrowed, the bit error rate is deteriorated, and the image correction processing is performed. Is performed, it is possible to smoothly switch scenes without inserting uncomfortable data into a part of the video.

[Brief description of the drawings]

FIG. 1 is a main block diagram showing a configuration of a reproducing system of a recording / reproducing apparatus according to a first embodiment of the present invention.

FIG. 2 is a track pattern diagram during insert recording in a recording / reproducing apparatus.

FIG. 3 is a track pattern diagram showing a problem during insert recording in the recording / reproducing apparatus.

FIG. 4 is a waveform diagram showing a playback envelope state during insert recording in the recording / playback apparatus.

FIG. 5 is a main block diagram showing a configuration of a reproducing system of a conventional recording / reproducing apparatus.

FIG. 6 is a main block diagram showing the configuration of a recording system of the recording / reproducing apparatus.

[Explanation of symbols]

 101, 501, 605 Magnetic recording medium 102, 502, 604 Head 103, 503 Decoding circuit 104, 504 Error correction circuit 105, 504 Error correction circuit 106 1 frame storage circuit 107 Output switching circuit 108, 506, 601 Video / audio signal processing Circuit 602 Error correction coding circuit 603 Recording coding circuit

──────────────────────────────────────────────────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 H04N 5/91 N H04N 5/7826 5/92 H 5/92 7 / 13 A 7/24 5/782 A F term (reference) 5C018 AA01 AB04 AB07 5C053 FA14 FA21 GB11 GB15 KA03 KA08 KA25 5C059 KK01 KK39 RF05 RF07 RF09 SS11 5D044 AB05 AB07 BC01 BC04 CC03 DE69 DE82 FG10

Claims (2)

[Claims] 1. A digital magnetic recording / reproducing apparatus for converting a video signal and an audio signal into a digital signal and recording / reproducing the digital signal, comprising: decoding means for decoding a reproduction signal detected from a magnetic recording medium; Error correcting means for correcting an error of the reproduced signal decoded by the method based on the error correction code added at the time of recording to restore the original signal; and a reproduced signal having an error exceeding a correction limit of the error correcting means. Error correction means for performing correction processing on the frame, and storing the output signal of the error correction means for one frame.
Frame memory means, and output switching for selectively outputting an output signal of the error correction means and an output signal of the one-frame storage means based on information of the error correction means or the error correction means or an envelope level of a reproduced signal. Means, and a magnetic recording / reproducing apparatus comprising: 2. A digital magnetic recording / reproducing method for converting a video signal and an audio signal into a digital signal and recording / reproducing the digital signal, wherein: a decoding step of decoding a reproduction signal detected from a magnetic recording medium; An error correction step of correcting an error of the reproduced signal decoded by the above based on an error correction code added at the time of recording to restore an original signal; and a reproduced signal having an error exceeding a correction limit of the error correction step. An error correction step of performing a correction process on a frame, a one-frame storage step of storing one frame of an output signal of the error correction step, and information on the error correction step or the error correction step or an envelope level of a reproduced signal. Selecting the output signal of the error correction step and the output signal of the one-frame storage step. Magnetic recording and reproducing method and an output switching step of outputting manner.