JPH06284365A - Digital recording and reproducing device - Google Patents

Abstract

PURPOSE:To provide a digital recording and reproducing device for securing the continuity of consecutive recording. CONSTITUTION:Digitized input video signals are compressed in a compression part 22 and the prescribed group unit of recording signals composed of the compressed video signals and digitized audio signals is track-divided and recorded on a tape 11 at a magnetic head 13. A reproducing position detection signal corresponding to a reproducing track position in the group unit is detected in a reproducing position detection part 31 and relative phase relation with reference signals synchronized with the input video signals is detected and stored in a relative phase detection part 32. Based on the relative phase detected in the relative phase detection part 32, the compressed video signals and the digitized input audio signals are delayed over plural tracks and defined as the recording signals in delay adjustment parts 54 and 55. After setting the delay time of the delay adjustment parts so as to obtain the recording signals corresponding to the relative phase by the relative phase detection part 32 and the delay adjustment parts 54 and 55, reproducing is switched to recording by a switching device 25.

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. At the time of recording, the input video signal 211 is digitized by the A / D converter 201 into a digital video signal 212 having a predetermined bit width. The compression unit 202 performs information compression on the digital video signal 212 to produce a compressed video signal 213. The modulator 203 modulates the compressed video signal 213 suitable for magnetic recording and converts it into a modulated video signal 214. Further, the modulation unit 203 mixes the modulated video signal 214 with the pilot signal in a timely manner. The switching unit 204 is connected to the 204A side at the time of recording and sends the modulated video signal 214 to the magnetic head 13A,
13B, and recorded on the magnetic tape 11. The compressed video signal 213 is shuffled for each predetermined group unit (for each one frame) and divided into 6 tracks for recording.

At the time of reproduction, the magnetic heads 13A and 13B attached to the cylinder 12 reproduce the modulated video signal 215 recorded on the magnetic tape 11, the demodulation section 205 demodulates it into a compressed video signal 216, and the expansion section 206. The digital video signal 217 is expanded. D / A converter 2
07 converts the digital video signal 217 into an analog video signal 218 and outputs it.

[0005]

In such a digital recording / reproducing apparatus (for example, a digital VTR), when a new video signal is recorded on the magnetic tape which has already been recorded, the track which has already been recorded is recorded. And the connection of compression groups becomes partially discontinuous.
As a result, when playing a discontinuously recorded tape,
There is a drawback in that noise is generated in a reproduced image in this discontinuous portion and the quality of the reproduced screen is significantly impaired.

For example, as shown in FIG. 6, if new recording is performed in an already-recorded area, the continuity of the tracks will be lost at the new recording start position.
Further, when one frame, which is a unit of shuffling compression group, is divided into six tracks and recorded, the new recording start position also impairs the continuity of the six track units. As a result, when a tape with such discontinuous recording is played back, the playback tracking is disturbed due to the track discontinuity and the expansion operation is disturbed due to the discontinuity of the group unit, and the playback screen is temporarily affected by noise. Will occur.

The present invention provides a digital recording / reproducing apparatus which performs new recording while keeping track continuity and compression group unit continuity in consideration of solving such a drawback. Is.

[0008]

In order to solve the above problems, a digital recording / reproducing apparatus of the present invention comprises a compression means for information-compressing a digitized input video signal, and a compressed video signal and a digitized audio signal. Recording means for recording by dividing a predetermined group unit of the recording signal into N (where N is an integer of 4 or more) tracks and tracking control for performing tracking so that the signal is reproduced from a desired track during reproduction. Means, a reproduction position detecting means for detecting a reproduction position detection signal corresponding to a reproduction track position in the group unit from the reproduction signal, and a relative phase relationship between the reference signal synchronized with the input video signal and the reproduction position detection signal. Relative phase detection means for detecting and storing the compressed video signal based on the detected relative phase of the relative phase detection means And a delay adjusting means for delaying the input audio signal over a plurality of tracks and outputting it as a recording signal, and a switching means for switching between reproduction and recording of the magnetic head. The relative phase detecting means and the delay adjusting means correspond to the relative phase. After the delay time of the delay adjusting means is set so as to obtain a recording signal, the switching means is switched from reproduction to recording and the recording state by the recording means is entered.

[0009]

According to the present invention, first, while tracking is performed at the time of reproduction by the tracking control means, recording is performed by the relative phase detection means and the delay adjustment means according to the relative phase of the reference signal synchronized with the input video signal and the reproduction position detection signal. The delay time of the delay adjusting means is set so as to obtain a signal. After that, the switching means is switched from the reproduction to the recording and the recording state by the recording means is changed to ensure the continuity of the track and the continuity of the compression group unit.

[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 steady-state operation during recording will be described. The magnetic tape 11 is sandwiched between the capstan shaft 16 of the capstan 15 and the pinch roller 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,
The tape 11 runs at a predetermined constant speed. The cylinder 12 on which the magnetic heads 13A and 13B are mounted is rotationally controlled in synchronization with a cylinder synchronization signal 113 having a frequency three times as high as the frame synchronization signal of the input video signal 101.

The input video signal 101 is digitized by the AD converter 21 into a digital signal having a predetermined bit width (for example, 8 bits). In the compression unit 22, the digital video signal 102 is D
Information compression such as CT conversion, shuffling, and variable length coding is performed, and the information amount is compressed to about 1/5 to / 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 in the fixed delay unit 52 by an amount equal to the delay time of the video signal in the compression unit 22. The delay adjustment unit 23 includes a video delay adjustment unit 55, an audio delay adjustment unit 54, and a synthesis unit 53. Each delay adjustment unit compresses the compressed video signal 1 for a delay time corresponding to the relative phase signal 114 of the relative phase detection unit 32.
03 and digital audio signal 153 are delayed to produce delayed video signal 104 and delayed audio signal 154.
The delayed video signal 104 and the delayed audio signal 154 combine the delayed video signal 104 and the delayed audio signal 154.
In time, the signals are time-divisionally combined into a recording signal 155. The recording signal 155 is modulated by the modulator 24 (for example, interleaved NRZI modulation, 8-14 modulation or 8-10 modulation) suitable for magnetic recording, and the modulated recording signal 10 is recorded.
5 is output.

In the modulator 24, digital bit modulation or analog signal addition
The pilot signal of the first frequency f1 or the second frequency f2 is mixed in the modulated recording signal 105 in a timely manner. At the time of recording, the switch circuit of the switching unit 25 is connected to the side of 26a, and the modulated recording signal 105 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. One frame of the video signal and the audio signal are divided and recorded in six tracks. Since the compressed video signal and the digital audio signal are time-divisionally combined in the recording signal, the video portion and the audio portion are divided into regions and formed on the track. An information signal including track numbers 1 to 6 and the like is sequentially recorded in each track in time division with the modulated video signal so that the track position information in the frame can be detected. Further, the pilot signals of the first frequency f1 and the second frequency f2 are recorded in order every two tracks with the track having no pilot signal interposed therebetween. In order to record the 1-frame modulated recording signal 105 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. Further, the modulator 24 outputs the modulated recording signal 105 for each track in synchronization with the timing of the cylinder synchronization signal 113.

FIG. 3 shows a more detailed track pattern. The recording azimuth of each track is the magnetic head 13A,
Corresponding to azimuth of 13B, the tracks are alternately different, and solid recording without a guard band is performed.
Further, the modulated recording signal is divided into blocks and recorded even in the track. Therefore, during playback, demodulation / expansion is performed each time a divided block in the track is played back, and the block is inserted into the screen area occupied (reverse operation of shuffling) to form a composite playback video signal. You can

Next, the operation of recording a new video signal by connecting to an already recorded area will be described. First, the switching unit 25 is connected to the side of 26b and operates in the reproduction state. The cylinder control unit 14 synchronizes with the cylinder synchronization signal 113 of the reference signal generation unit 33, and
Control the rotation. The cylinder synchronization signal 113 of the reference signal generation unit 33 is a timing signal having a frequency three times that of the frame reference signal 112. The magnetic heads 13A and 13B reproduce the modulated recording signal recorded on the magnetic tape 11 and output a head reproduction signal 106. Since the switch circuit of the switching unit 25 is switched to the 26b side, the head output is transmitted as the modulated reproduction signal 110.

The tracking controller 34 extracts the pilot signal contained in the modulated reproduction signal 110, compares the magnitudes of the frequency components f1 and f2, and rotates the capstan 15 so that the two components are balanced. To control. The pilot signals are compared every two tracks, and the magnitudes of the pilot signal f1 and f2 components leaked from adjacent tracks to the magnetic head 13A reproducing the track on which the pilot signal is not recorded are compared. I am trying to do it. 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 to control the rotational speed of the capstan 15. I have to. As a result, the magnetic heads 13A, 13
B accurately tracks and reproduces the track in which the azimuth coincides.

The reproduction position detecting section 31 includes a modulated reproduction signal 11
Playback track position is detected from 0, track position signal 1
11 is output. As the track position signal 111, a timing signal indicating the generation timing of the track number 1 is used (or the track position number within one frame unit can be used).

The relative phase detecting section 32 comprises a reference signal generating section 3
The time interval corresponding to the generation timing of the frame reference signal 112 of No. 3 and the relative phase of the track position signal 111 of the reproduction position detector 31 is detected. The relative phase signal 114 of the relative phase detector 32 is sent to the delay adjuster 23. The delay adjustment unit 23 is configured to include, for example, a random access memory, stores the compressed video signal 103 and the digital audio signal 153 in the memory, applies appropriate delay, and outputs the delayed video signal 104 and the delayed audio signal 154. The delay time of the delay adjustment unit 23 is adjusted by the relative phase signal 114 of the relative phase detection unit 32.

The tracking control section 34 controls the rotational speed of the capstan 15 so that the magnetic head is on-track to the recorded track by the pilot signal included in the modulated reproduction signal 110, and performs tracking control. Further, the tracking control unit 34 detects stable pull-in of the tracking control by the tracking error signal, and outputs the storage command signal 115 when the stable state is entered,
The current relative phase signal 114 of the relative phase detector 32 is stored and held. As a result, the delay adjustment unit 2
3 is the compressed video signal 103 and the digital audio signal 15 for the delay time corresponding to the stored relative phase signal 114.
Delay 3 That is, the delayed video signal 104 and the delayed audio signal 154 are the recording signal 15 in which these are combined.
5 or modulated recording signal 105, modulated reproduction signal 1
The delay is adjusted so that the frame phase and 10 will match.
After that, the tracking control unit 34 detects the start time of the next frame unit from the track position signal 111, outputs the switching signal 116 to switch the switching unit 25 to the side of 26a, and at the same time, records the capstan 15 at the time of recording. Switch to control at a predetermined constant rotation speed. As a result, the magnetic heads 13A and 13B cause the modulation recording signal 105 of the modulation unit 24 to change.
To move to record.

Next, the effect of the digital recording / reproducing apparatus of the present invention will be described. When performing new recording on an already-recorded area, first, it is operated in a reproducing state, and tracking control using a pilot signal on the track is performed by the tracking control unit 34 to maintain track continuity. .

Next, in this reproducing state, the reproducing position detecting section 31 detects the reproducing track position in frame units from the reproducing signal, and the relative phase detecting section 32 detects the input video signal 101.
The relative phase signal 114 corresponding to the relative phase difference between the frame reference signal 112 and the reproduction position detection signal 111 synchronized with is detected, stored and held. The delay adjustment unit 23 uses the relative phase signal 1
14, the delay time is set according to 14, and the compressed video signal 103
And a delayed audio signal 154 delayed from the digital audio signal 153 are output. The delay adjustment unit 23 is capable of delay adjustment for at least 6 tracks. As a result, the recorded signal 155 and the modulated reproduction signal 11 from the track when viewed in one frame period.
The reproduction timing of 0 becomes the same.

Next, the recording operation is switched from the start of the frame after the delay adjustment to the modulated recording signal 105 of the modulator 24.
To record. At this time, the tracking control unit 34 is switched so as to control the rotation of the capstan 15 at a constant rotation speed, and the tape 11 is travel-controlled at a constant speed. As a result, recording is started so that the frame recording start track is continuous with the already recorded frame unit.

In this way, the continuity of tracks at the start of recording and the continuity of frame units (shuffling group units) can be realized. Therefore, when the magnetic tape recorded in this way is reproduced, it is possible to obtain a high-quality reproduction screen with no noise even at the recording joint.

The tracking control for controlling the tape running may be performed only by temporarily performing the track reproducing operation by the pilot signal, and forcibly adjusting the reproducing track to the frame reference signal 122 synchronized with the input video signal 101. There is no need to perform a timing adjustment control operation. Therefore, tracking control is significantly simplified.

Further, since the compressed video signal 103 is delayed, the video information within the delay time is reduced, and the memory amount of the delay adjusting section 23 can be greatly reduced.

Further, since the audio signal is delayed by the delay adjusting section 54 like the compressed video signal, there is no time lag with the video signal.

In the configuration shown in FIG. 1, the function of the fixed delay section 52 may be included in the audio delay adjustment section 54.
That is, the audio delay adjustment unit 54 gives a delay time obtained by adding the delay time in the fixed delay unit 52 to the delay time for the adjustment added to the audio signal. By doing so, the fixed delay unit can be omitted.

Next, another embodiment of the present invention will be described with reference to FIG. FIG. 4 is a block diagram of another embodiment of the digital recording / reproducing apparatus of the present invention. The difference from the configuration of FIG.
That is, the order of the two delay adjusting units and the combining unit 53 in the delay adjusting unit 23 is exchanged. The synthesis unit 53 first synthesizes the compressed video signal 103 and the digital audio signal 153 into a synthesis signal 156, and then the synthesis signal delay adjusting unit 56 adjusts the delay time based on the detected relative phase with respect to the synthesis signal 156. Do. Except for this difference in processing order, the operation is exactly the same as in the previous embodiment, so detailed description will be omitted. The amount of signal information to be delayed is shown in Fig. 1.
Since there is no difference from the configuration of FIG. 1, the total amount of memory required for the delay adjustment unit is the same as the configuration of FIG. Therefore, in addition to the effect of the embodiment of FIG. 1, the present embodiment has an advantage that the configuration is simplified because the delay adjustment unit collectively adjusts the video and audio.

In the embodiment, the pilot signal multiplexed and recorded on the track is reproduced to perform the tracking control, but the present invention is not limited to such a case,
For example, recording / reproducing a pilot signal at a predetermined location on a track to apply tracking,
Further, tracking may be performed using a control signal recorded on a linear track.

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

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

[0034]

As described above, the digital recording / reproducing apparatus of the present invention compresses the compressed video signal for the time corresponding to the relative phase between the reference signal synchronized with the input video signal and the reproduction position detection signal while tracking during reproduction. After delaying the audio signal and setting the delay time of the delay adjustment unit so as to obtain a recording signal whose phase matches that of the reproduction signal, by switching from reproduction to recording and shifting to the recording state, track continuity is improved. Since continuity is ensured for each shuffling group, if a digital VTR is constructed by the digital recording / reproducing apparatus of the present invention, a high-quality reproduced image without noise due to recording discontinuity is always obtained. Things are possible.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a diagram 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 configuration diagram showing another embodiment of the present invention.

FIG. 5 is a block diagram of a conventional example

FIG. 6 is a diagram for explaining the operation of a conventional example.

[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 52 fixed delay unit 23 delay adjustment unit 53 synthesis unit 24 modulation unit 25 Switching unit 31 Playback position detection unit 32 Relative phase detection unit 33 Reference signal creation unit 34 Tracking control unit

Claims (4)

[Claims] 1. A compression means for information-compressing a digitized input video signal, and N predetermined group units of a recording signal composed of a compressed video signal and a digitized audio signal (where N is an integer of 4 or more). Recording means for dividing and recording on each track, tracking control means for performing tracking so that a signal is reproduced from a desired track at the time of reproduction, and reproduction position detection signal according to a reproduction track position within the group unit A reproduction position detecting means for detecting from the signal, a relative phase detecting means for detecting and storing a relative phase relationship between the reference signal synchronized with the input video signal and the reproduction position detecting signal, and a relative phase detected by the relative phase detecting means. Delay for delaying the compressed video signal and the digitized input audio signal over a plurality of tracks based on The delay adjusting means is provided with a switching means for switching between reproduction and recording of the magnetic head, and the delay time of the delay adjusting means is set by the relative phase detecting means and the delay adjusting means so as to obtain a recording signal corresponding to the relative phase. After that, the digital recording / reproducing apparatus is characterized in that the switching means is switched from reproduction to recording and a recording state by the recording means is entered. 2. A compression means for information-compressing a digitized input video signal, and N recording signals composed of one frame unit of the compressed video signal and a digitized audio signal accompanying the video signal of the one frame unit ( Here, N is an integer of 4 or more), recording means for dividing the recording into tracks, tracking control means for performing tracking at the time of reproduction by a pilot signal recorded on the track, and reproduction within the one frame unit Reproduction position detecting means for detecting a reproduction position detection signal corresponding to the track position from the reproduction signal, and relative phase detecting means for detecting and storing the relative phase relationship between the reference signal synchronized with the input video signal and the reproduction position detection signal. And a plurality of trajectories of the compressed video signal and the digitized input audio signal based on the detected relative phase of the relative phase detection means. A delay adjusting means for delaying the recording signal and outputting it as a recording signal, and a switching means for switching between reproduction and recording of the magnetic head, so that the relative phase detecting means and the delay adjusting means obtain a recording signal corresponding to the relative phase. After setting the delay time of the delay adjusting means,
A digital recording / reproducing apparatus, wherein the switching means is switched from reproduction to recording and the recording state by the recording means is entered. 3. The delay adjusting means delays the digitized input audio signal over a plurality of tracks based on the detected relative phase of the relative phase detecting means, and outputs the delayed audio signal, and the relative phase detecting means. From the video delay adjusting means for delaying the compressed video signal over a plurality of tracks based on the detected relative phase and outputting the delayed video signal, and the synthesizing means for synthesizing the delayed audio signal and the delayed video signal and outputting the synthesized signal as a recording signal. The digital recording / reproducing apparatus according to claim 1 or 2, wherein the digital recording / reproducing apparatus is configured. 4. The delay adjusting means combines the compressed video signal and the digitized input audio signal and outputs a combined signal, and the combined signal over a plurality of tracks based on the detected relative phase of the relative phase detecting means. 3. The digital recording / reproducing apparatus according to claim 1, further comprising a combined signal delay adjusting means for outputting the delayed combined signal as a recording signal.