JPH06268965A - Digital recording and reproducing device - Google Patents

Abstract

PURPOSE:To provide the digital recording and reproducing device in which the mode transfer time to the reproduction state is reduced. CONSTITUTION:The device is made up of magnetic heads 13A, 13B dividing one group unit of a video signal subject to digitized information compression and digitized audio signal into N-sets (N is an integer of 4 or over) tracks and recording the signal, a tracking control section 38 controlling the tracking at reproduction, a reproduction position detection section 36 detecting a reproduction tracking position in one group unit from the reproduction signal, a relative position detection section 37 detecting a relative relation between a reference signal and a reproduction track position, a delay adjustment section 32 adjusting a delay time of the reproduction signal based on the detected relative phase of the relative position detection section 37 over plural tracks based on the detected relative phase of the relative position detection section 37, a video expansion section 33 expanding the delay reproduction signal of the delay adjustment section 32 and decoding it into an analog video signal, and a fixed delay section decoding the analog audio signal from the delay reproduction signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital recording / reproducing apparatus for recording / reproducing a digital information signal which is obtained by digitizing a video signal to compress and band compress the information.

[0002]

2. Description of the Related Art A digital recording / reproducing apparatus such as a digital tape recorder (digital VTR) that digitizes and records / reproduces a video signal does not deteriorate the recording / reproducing video signal due to dubbing, as compared with an analog recording / reproducing apparatus. It has been put to practical use for business purposes. However, the digitized video information has a large amount of information, and there is a disadvantage that a large amount of tape is consumed for recording and reproducing the information, and in order to compress the amount of information for home use,
Predictive coding, DCT conversion coding, variable length coding, etc. are performed, and information compression / bandwidth compression is performed for recording / reproduction. For example, a method is conceivable in which one frame of video information is used as a basic unit for information compression and divided into a plurality of continuous tracks for recording.

This will be described with reference to FIG. A magnetic tape 11 having a predetermined tape width is wound around a cylinder 12 and travel-controlled at a predetermined speed. The magnetic heads 13A and 13B attached to the rotary cylinder section reproduce the modulated video signal 210 recorded on the magnetic tape 11, the demodulation section 201 demodulates it into a compressed video signal 211, and the decompression section 202 converts it into a digital video signal 213. Extend. The frame reference signal 212 output from the reference signal generation unit 204 is input to the decompression unit 202 and determines the insertion position of the time reference (for example, vertical synchronization timing) of the frame of the digital video signal 213. D / A converter 20
3 is a digital video signal 213 and an analog video signal 2
Converted to 14 and output.

[0004]

However, in such a digital recording / reproducing apparatus (digital VTR), when the mode is changed from the fast-view reproduction (cue review) state to the normal reproduction, the reproduction position of the tape is the frame reference signal. However, there is a drawback that it does not match 212 and discontinuity of the reproduction screen occurs.

For example, as shown in FIG. 2A, when the compressed video signal of one frame is divided into 6 tracks and recorded on the magnetic tape 11, the mode is changed from the quick view reproduction state to the normal reproduction state. , Even if the track positions are sequentially reproduced normally as shown in FIG.
The phase relationship with the frame reference signal 212 shown in (c) is not accurately determined. As a result, the frame reference signal 212
Due to the deviation of the reproduction track position, the insertion timing of the frame reference time of the video signal is incorrect, and the normal video signal cannot be restored.

In order to set the insertion timing to an accurate position, a method of changing the reproduction position of the magnetic tape 11 by a predetermined track and adjusting the reproduction track position to the frame reference signal 212 can be considered. However, such a method has a drawback that it takes a lot of time until the final stabilization of the operation of shifting the reproduction track position of the magnetic tape 11.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above drawbacks, and an object of the present invention is to provide a digital recording / reproducing apparatus capable of quickly correcting the insertion timing of the frame reference time to an accurate position. is there.

[0008]

In order to solve the above problems, a digital recording / reproducing apparatus of the present invention comprises a group of digitized information-compressed video signals and a group of digitized audio signals. And N are divided into N tracks (where N is an integer of 4 or more) for recording, a tracking control unit for controlling tracking at the time of reproduction, and a reproduction track position within one group unit are reproduced. A reproduction position detecting means for detecting from a signal, a relative phase detecting means for detecting a relative relationship between a reference signal and the reproduction track position, and a video information signal included in the reproducing signal based on the detected relative phase of the relative phase detecting means. And delay information adjusting means for adjusting the delay time of the audio information signal over a plurality of tracks, and the video information delayed by the delay adjusting means. A video decompressing means for restoring into an analog video signal by extending the signal is obtained by the speech information signal delayed adjusted by the delay adjustment means to comprise an audio signal reproduction means for restoring an analog audio signal.

[0009]

According to the present invention, the relative phase detection means detects the relative relationship between the reference signal and the reproduction track position, and the delay adjustment means delays the reproduction signal in accordance with the relative phase, thereby instantaneously delaying the reference signal and the reference signal. It is possible to match the timings of the reproduced signals generated. Further, by applying the same delay adjustment to the audio signal, the timing relationship between the video signal and the audio signal can be preserved.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A digital recording / reproducing apparatus according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a digital VTR according to the present invention.

First, the operation during recording will be described. The magnetic tape 11 is the capstan shaft 16 of the capstan 15.
It is sandwiched between the pinch rollers 17 and runs at a speed corresponding to the rotation speed of the capstan 15. At the time of recording, the capstan 15 rotates at a predetermined constant speed, and the tape 11
Runs at a predetermined constant speed. Magnetic head 13A, 1
The cylinder 12 having 3B mounted thereon is rotationally controlled in synchronization with a cylinder synchronizing signal having a frequency three times as high as the frame synchronizing signal of the input video signal 101.

The input video signal 101 is digitized by the A / D converter 21 into a digital signal having a predetermined bit width (for example, 8 bits). The digital video signal 102 is subjected to DCT conversion, shuffling, variable-length coding, etc., with one frame as a group unit, and its information amount is ⅕.
It is compressed to about / 10. The input audio signal 151 is digitized by the A / D converter 51 into a digital signal having a predetermined bit width (for example, 16 bits). The digital audio signal 152 is delayed by the fixed delay unit 52 in an amount equal to the delay amount of the video signal in the compression unit 22.

The compressed digital video signal 103 and digital audio signal 153 are time-divisionally combined by the combining unit 53. Synthetic recording signal 1 in which video signal and audio signal are synthesized
The modulator 54 performs modulation (for example, interleaved NRZI modulation, 8-14 modulation or 8-10 modulation) suitable for magnetic recording by the modulator 23, and outputs a modulated recording signal 104. In the modulator 23, the first bit is converted by digital bit modulation or analog signal addition.
The pilot signal of the frequency f1 or the second frequency f2 is mixed in the modulated recording signal 104 in a timely manner. At the time of recording, the switch circuit of the switching unit 24 is connected to the 25a side,
The modulated recording signal 104 is sent to the magnetic heads 13A and 13B and recorded on the magnetic tape 11.

FIG. 2A shows a track pattern recorded on the magnetic tape 11. The modulated recording signal of one frame is divided into six tracks and recorded. Each track is divided into a compressed video signal section and a compressed audio signal section. In addition, track numbers 1 to 6 are sequentially assigned to each track.
Is recorded together with the modulated recording signal, and indicates track position information within the frame. Further, a pilot signal having a first frequency f1 and a pilot signal having a second frequency f2 are recorded in order every two tracks with a track having no pilot signal interposed therebetween. In order to record the 1-frame modulated recording signal 104 by dividing it into 6 tracks, the cylinder 12 at the time of recording is synchronized with the cylinder synchronization signal having a frequency three times as high as the timing reference signal of 1-frame of the input video signal 101. Is rotating. A track without a pilot signal is recorded by the magnetic head 13A, and a track containing a pilot component is recorded by the magnetic head 13B.

FIG. 3 shows a detailed track pattern. The recorded azimuth of each track is alternately different for each track. Further, the modulated recording signal is divided into blocks and recorded even in the track. The numbers written in each block are track numbers, and A to D are intra-track block addresses, and the block addresses are recorded together with the modulated recording signal like the track numbers. During quick view reproduction, demodulation / expansion is performed every time one divided block in a track is reproduced, and the block is embedded in the screen area occupied by the block to form a combined quick view video signal.

Next, the operation when shifting to the normal reproduction will be described. In normal reproduction, all of the modulated recording signals recorded on the track are reproduced accurately, and high-accuracy signal reproduction is performed. The cylinder controller 14 controls the rotation of the cylinder 12 in synchronization with the cylinder synchronization signal 124 of the reference signal generator 35. Cylinder synchronization signal 12 of the reference signal generator 35
Reference numeral 4 is a timing signal having a frequency three times that of the frame reference signal 122. The magnetic heads 13A and 13B reproduce the modulated recording signal recorded on the magnetic tape 11 and output a head reproduction signal 105. During playback, the switching unit 24
The switch circuit of is switched to the side of 25b and transmits the head output as the modulated reproduction signal 110.

The tracking control unit 38 extracts the pilot signal included in the modulated reproduction signal 110, compares the magnitudes of the frequency f1 component and the frequency f2 component, and rotates the capstan 15 so that both are balanced. To control. The pilot signals are compared every two tracks, and the magnitudes of the pilot signal components leaked from the adjacent tracks to the magnetic head 13A reproducing the track in which the pilot signal is not recorded are compared. There is. Also, the polarity of comparison of pilot signals is reversed every two tracks, and the magnitude of the pilot component of the preceding track and the magnitude of the pilot component of the following track are always compared,
The rotation speed of the capstan 15 is controlled. As a result, the magnetic heads 13A and 13B accurately track and reproduce the tracks in which the azimuths match.

The modulated reproduction signal 110 is demodulated by the demodulator 31 to obtain a compressed reproduction signal 111. The demodulation unit 31 outputs a track information signal 120 including reproduction track position information from the modulated reproduction signal 110. Playback position detector 36
Detects the reproduction track position from the track information signal 120 and outputs a track position signal 121.

The relative phase detecting section 37 includes a reference signal generating section 3
The relative phase of the reproduction track position is detected by latching the track position signal 121 of the reproduction position detector 36 at the timing of generation of the frame reference signal 122 of No. 5. The relative phase signal 123 of the relative phase detector 37 is sent to the delay adjuster 32. The delay adjustment unit 32 is configured to include, for example, a random access memory, and the compressed reproduction signal 1
11 is stored in the memory, an appropriate delay is applied, and the delayed reproduction signal 112 is output. The delay time of the delay adjusting section 32 is adjusted by the relative phase signal 123 of the relative phase detecting section 37.

The delayed reproduction signal 112 is separated into a video information signal 158 and an audio information signal 155 by the separation unit 54. Since the video information signal and the audio information signal are time-divisionally combined in the delayed reproduction signal, the separation unit 54 separates them by referring to the block address or the like.

The video information signal 158 is input to the decompression unit 33, which decompresses and restores the compressed video information signal 158,
The digital video signal 113 is obtained. The frame reference signal 122 is also input to the decompression unit 33, and the frame reference signal 12
The vertical synchronization signal of the frame is inserted at the timing of 2 (the vertical synchronization signal for each field is also generated and inserted). The digital video signal 113 is converted into an analog video signal 114 by the D / A converter 34 and output.

The audio information signal 155 is input to the fixed delay unit 55, and is delayed by an amount equal to that of the decompression unit 33 in order to maintain the timing relationship with the video signal.
56. The digital audio signal 156 is converted into an analog audio signal 157 by the D / A converter 56 and output.

Next, effects of the digital recording / reproducing apparatus of the present invention will be described. Generally, in a digital VTR that records and reproduces a video signal, it is required that the frame frequency of the output video signal always match a predetermined reference value. This is because the vertical synchronizing frequency of the TV monitor is fixed to a predetermined value. There is also an advantage that the input / output circuit configuration is simplified. However,
When performing the quick-view reproduction, in order to accurately demodulate the reproduction signal from the magnetic tape 11, the rotational speed of the cylinder 12 is changed and corrected from the rotational speed at the time of recording according to the running speed of the tape, and the magnetic head 13A, The relative speed between 13B and the tape 11 is kept the same as during recording. Therefore, the rotation of the cylinder 12 and the frame reference signal 12 at the time of quick playback
2 (and 3 times the frequency signal) are out of sync,
The phase relationship between the two becomes indefinite. At the time of quick playback, the magnetic head crosses and traces the track, so demodulates / decompresses and reproduces each divided block in the track, and inserts the video information of the normally reproduced block into the corresponding screen position. Output as a quick view video signal.

When shifting from such a quick view state to a normal reproduction state, the cylinder 12 is operated by the reference signal generating section 3
The rotation is controlled in synchronization with the cylinder synchronization signal 124 of No. 5. The tracking control unit 38 controls the rotation of the capstan and the running of the magnetic tape 11 by the pilot signal included in the modulated reproduction signal 110 reproduced from the magnetic heads 13A and 13B. As a result, the magnetic head 13
Tracking control is performed on the tracks A and 13B so that the tracks having the same azimuth are sequentially reproduced. The pilot signal used for tracking is repeated with 4 tracks as a cycle (4 track cycle), whereas the compressed video signal is recorded by dividing it into 6 tracks with one frame as a group unit (6 track division). There is. Therefore, in the stable pull-in state of tracking, the frame reference signal 1
The reproduction track position does not always coincide with that of No. 22 in terms of timing. For example, as shown in FIG. 2, a case may occur in which the phases change synchronously with a relative phase difference of 4 tracks. In this embodiment, even if such a relative phase difference occurs due to tracking, the relative position of the reproduction track with respect to the frame reference signal 122 is detected by the relative phase detection unit 37, and the delay adjustment unit 32 detects the relative position according to the detected relative phase. The delay time can be adjusted quickly and accurately, and the timing of the delayed reproduction signal 112 can be easily matched with the frame reference signal 122. As a result, the transition time from the quick view reproduction to the normal reproduction is significantly shortened, and the operability as a digital recording / reproducing apparatus is significantly improved.

Further, since the delay time of the audio signal is adjusted in the same manner as the video signal, the deviation of the video and audio does not occur. Further, the tracking for controlling the tape running does not need to perform the timing matching operation to the frame reference signal 122. Therefore, tracking control is significantly simplified. Furthermore, since the compressed reproduction signal 111 is delayed, the video information within the delay time is reduced, and the memory amount of the delay adjustment unit 32 can be significantly reduced.

Next, another embodiment of the present invention will be described with reference to FIG. FIG. 5 is a block diagram of the second embodiment of the digital recording / reproducing apparatus of the present invention. The basic difference from FIG. 1 is that the separation unit and the delay adjustment unit are replaced. Accordingly, the delay adjusting unit is divided into an audio information signal delay adjusting unit 57 and a video information signal delay adjusting unit 58, each of which receives the relative phase signal 123 from the relative position detecting unit and adjusts the delay time. Here, the delay adjusting unit for voice information includes the function of the fixed delay unit 55 in FIG. 1, and the block of the fixed delay unit 55 is omitted. Other configurations and operations are the same as those in FIG. Even with such a configuration, the required memory amount is the same as a whole. Therefore, in addition to the effect of the embodiment of FIG. 1, the present embodiment has an advantage that the memory management necessary for the fixed delay can be omitted by omitting the fixed delay unit 55.

Incidentally, in the embodiment, the pilot signal multiplexedly recorded on the track is reproduced to perform the tracking control, but the present invention is not limited to such a case and, for example, a portion may be provided at a predetermined position on the track. Therefore, the pilot signal may be recorded / reproduced to perform tracking, or the control signal recorded on the linear track may be used to perform tracking.

The group unit for compression / division is not limited to one frame, but may be several frames.

Furthermore, in the above-mentioned embodiment, the transition from the quick-view reproduction state to the normal reproduction state has been described. However, the present invention is not limited to such a case, but slow reproduction, still reproduction, and a mode from the stopped state to the normal reproduction. Even during the transition, the above-mentioned remarkable effects can be obtained.

Besides, various modifications can be made without changing the output signal of the present invention.

[0031]

According to the digital recording / reproducing apparatus of the present invention,
The relative relationship between the reference signal and the reproduction track position is detected by the relative phase detecting means, and the reproduction signal is delayed by the delay adjusting means according to the relative phase, so that the timing of the reference signal and the delayed reproduction signal is instantaneously changed. You can match. As a result, if a digital VTR is constructed by the digital recording / reproducing apparatus of the present invention, the mode transition time from the quick view reproduction to the normal reproduction is significantly shortened, and the operability can be greatly improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a time chart for explaining the operation of the present invention.

FIG. 3 is a track pattern diagram for explaining the operation of the present invention.

FIG. 4 is a block diagram of a conventional digital recording / reproducing apparatus.

FIG. 5 is a block diagram showing a second embodiment of the present invention.

[Explanation of symbols]

 11 magnetic tape 12 cylinders 13A, 13B magnetic head 14 cylinder control unit 15 capstan 16 capstan shaft 17 pinch roller 21, 51 A / D conversion unit 22 compression unit 23 modulation unit 24 switching unit 31 demodulation unit 32 delay adjustment unit 33 expansion Part 34,56 D / A converter 35 Reference signal generator 36 Playback position detector 37 Relative phase detector 38 Tracking controller 52,55 Fixed delay part 53 Combiner 54 Separator

Claims (2)

[Claims] 1. A group of video signals digitized by information compression and a group of audio signals digitized by 1.
Recording means for dividing the group unit into N tracks (where N is an integer of 4 or more) for recording, tracking control means for controlling tracking during reproduction, and reproduction track position within the group unit A reproducing position detecting means for detecting from the reproducing signal, a relative phase detecting means for detecting a relative relationship between the reference signal and the reproducing track position,
Delay adjusting means for adjusting the delay time of the video information signal and the audio information signal included in the reproduction signal based on the detected relative phase of the relative phase detecting means over a plurality of tracks;
Video decompression means for decompressing the video information signal delay-adjusted by the delay adjustment means to restore it to an analog video signal, and audio signal reproduction means for restoring an analog audio signal from the audio information signal delay-adjusted by the delay adjustment means. And a digital recording / reproducing apparatus comprising. 2. N pieces of one frame unit of a video signal which is digitized and subjected to information compression, and N digitized audio signals which accompany the video signal of the one frame unit (where N is 4 or more). Recording means for dividing and recording into (integer) tracks, tracking control means for controlling tracking at the time of reproduction by a pilot signal recorded on the track, and reproduction track position in the one frame unit is detected from the reproduction signal A reproduction position detecting means,
Relative phase detecting means for detecting the relative relationship between the reference signal and the reproduction track position, and a plurality of delay times of the video information signal and the audio information signal included in the reproduction signal based on the detected relative phase of the relative phase detecting means. A delay adjusting means for adjusting over the tracks, a video expanding means for expanding the video information signal delay adjusted by the delay adjusting means to restore an analog video signal, and an analog from the audio information signal delay adjusted by the delay adjusting means. A digital recording / reproducing apparatus comprising: an audio signal reproducing means for restoring an audio signal.