JP2860986B2 - Signal copying method and signal copying apparatus - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a video tape recorder (hereinafter, referred to as a VTR).
And a magnetic recording / reproducing apparatus used for the method.

2. Description of the Related Art In order to copy a video signal recorded on a magnetic tape by a VTR that records a video signal in the form of an analog signal,
It is sufficient to prepare at least two VTRs and record the reproduced signals on the other hand in a local area. Such a method is used in a home VTR such as the VHS system. In this case, two VTs
As a result of the accumulation of the time axis error of R, the image quality is significantly deteriorated, which is not suitable for realizing high-quality video signal copying.

More recently, a system for compressing a color signal and recording a video signal multiplexed on a time axis with a luminance signal has been studied. In this case, a color signal displayed after being expanded on the time axis after reproduction is displayed on a screen. The time axis error is magnified, causing more significant image quality degradation.

There is a method of avoiding accumulation of time axis errors by adopting a TBC (time base collector) in such an analog recording VTR.

However, in such a copying method in an analog recording VTR, a copying signal is transmitted and received in an analog format. In general, when a TBC performed by digital processing is interposed, the reproduction of the TBC is performed. A / D converter on the side, recording side
It is necessary to interpose a D / A converter, and there is a problem that image quality is deteriorated by a low-pass filter provided in combination with these converters.

An object of the present invention is to solve the above problems and to provide a signal copying method and a magnetic recording / reproducing apparatus that do not have a time axis error and do not cause deterioration in image quality.

Means for Solving the Problems In order to achieve the above object, the present invention has been made to solve at least the above problems in a method of copying a signal including an analog video signal. Reproducing the analog video signal in which the reproduced chrominance signal is multiplexed with the luminance signal on the time axis, digitizing the reproduced analog video signal, and transferring the digital signal to a second magnetic recording / reproducing apparatus And recording the transferred digital signal as an analog signal in the second magnetic recording / reproducing apparatus.

According to the present invention, the image quality of a video signal is prevented from being deteriorated by transmitting and receiving a video signal by a digital signal through a copying terminal during copying by the above-described copying method.

Embodiment An embodiment of the present invention will be described with reference to FIGS.

In FIG. 1, 1 is a VTR1, 2 is a signal processing unit of the VTR1, 3
Denotes a magnetic head, 4 denotes a magnetic tape, 5 denotes a VTR2, 6 denotes a signal processing unit of the VTR2, 7 denotes a magnetic head, and 8 denotes a magnetic tape.
Vin is a video signal input, Pin is an audio signal input recorded as a PCM signal, Lin is an audio signal input recorded on a linear track, Vout is a video signal output, and Pout is a main audio signal (signal recorded by PCM) output , Lout is a sub audio signal (signal recorded on a linear track) output, and Tout is a time code output signal. The recording and reproduction signals A and B are analog signals, D1 to D4 are copy signals, D1 is a digital video signal, D2 is a PCM audio digital signal, D3 is an analog audio signal, and D4 is a time code signal.

FIG. 2 shows details of the VTRs 1 and 2. Since these have exactly the same configuration, only VTR1 is shown.

The VTR 1 divides a high-definition signal having 1125 scanning lines and a field frequency of 60 Hz into two channels, and records one field on six tracks at a drum rotation speed of 90 Hz. The main audio is recorded on the extension of the video track by two-channel PCM, and the sub audio and the time code signal can be recorded on the linear track.

The configuration of this VTR will be described with reference to FIG. 9 is a prefilter for A / D conversion of the Y signal, 10 is an A / D converter for Y signal, 11 is a prefilter for A / D conversion for the Cw signal, and 12 is C
w A / D converter for signals, 13 is a prefilter for A / D conversion for Cn signals, 14 is an A / D converter for Cn signals, 15 is a TCI encoder,
16 and 17 are changeover switch circuits, 18 and 19 are shuffling memories, 20 and 21 are reference signal insertion circuits, and 22 and 23 are D / A.
Converters, 24, 25 are post filters for D / A converters, 26, 27
Is an FM modulator, 28 is a recording timing switch, 29, 30, 31, 3
2 is a recording amplifier, and 33, 34, 35 and 36 are recording / reproduction mode changeover switches. 37, 38, 39, and 40 are A1, B1, A2, and B2 heads, respectively, and 4 is a magnetic tape.

41, 42 are prefilters for A / D conversion of audio signals, 43, 44
Is an audio signal A / D converter, 45 and 46 are changeover switch circuits, 47 is an audio PCM recording signal processing circuit, 48 is a time axis compression circuit, 49, 50, 51, and 52 are reproduction amplifiers, and 53 is a reproduction timing switch. Switches, 54, 55 are FM demodulators, 56, 57 are playback A / D
A pre-filter for conversion, 58 and 59 are A / D converters, 60 and 61 are reverse shuffling memories, 62 is a level correction circuit, 63 is a TCI decoder, 64, 65, and 66 are for Y signals, and for Cw signals, D / A for Cn signal
The converters 67, 68, and 69 are post filters for the D / A converter of the Y signal, the Cw signal, and the Cn signal. 70 and 71 are binarization circuits, 72 is a time axis expansion circuit, 73 is an audio PCM reproduction signal processing circuit, and 74 and 75
Is a D / A converter for audio signals, and 76 and 77 are post filters. 78 and 79 are analog audio signal delay circuits, 80 is an analog recording amplifier, 81 is a recording / playback mode switch, 82
Is an audio head, 83 is a reproduction amplifier, 84 is a time code generation circuit, 85 is a time code decoding circuit, 86 is a time code recording amplifier, 87 is a recording / reproduction mode switch, 88 is a time code recording / reproducing head, and 89 is a time code. A reproduction amplifier, 90 is a copy mode changeover switch, and 91 is a microcomputer.

Hereinafter, the operation will be described based on the above configuration. The input video signal Vin is input as a Y, Cw, cn component signal. After the Y signal is band-limited by the pre-filter 9,
It is digitized by the A / D converter 10. Similarly, Cw
After the signal is band-limited by the pre-filter 11, the A / D converter 1
2, and the Cn signal is band-limited by the pre-filter 13, and then digitized by the A / D converter 14, respectively. These signals are converted into two-channel signals by the TCI encoder 15 after the color signals are line-sequential. This is shown in FIG. TCI is an abbreviation of Time Compressed Integration, and is a general term for signal processing in which a color signal is compressed on the time axis and multiplexed with a luminance signal on the time axis. Input signal is Yin, Cwin, Cnin
3 channels. On the other hand, Y is extended on the time axis,
C performs time axis compression. At this time, C is line-sequential after being subjected to a vertical filter. By this processing, recording signals A and B of two channels are obtained. The suffix in the figure indicates the scanning line number.

The signals of the two channels formed as described above are supplied to the changeover switches 16 and 17 connected to the N side during normal recording.
And is input to the shuffling memories 18 and 19. Hereinafter, the switch for switching N / D is connected to the N side during normal recording / reproduction and copy / reproduction, and to the D side during copy / recording.

On the other hand, the copy video signal input D1in is given to the D-side inputs of the switches 16 and 17. The copy signal video input is obtained by extracting a signal corresponding to a TCI decoder input, that is, a TCI encoder output at the time of recording, from a reproduction signal of another VTR as described later. FIG. 3 shows the operation of the shuffling memory.

The shuffling referred to here is a recording method proposed in Japanese Patent Application Laid-Open No. 62-190981, and in order to record a highly correlated video signal on all six tracks forming one field, the shuffling is performed on the time axis of a scanning line. The sequence is changed and recorded. In the figure, the input signals A and B to the shuffling memory are two-channel TCI signals, and the vertical blanking is deleted, so that 1125 scanning lines of 1125 per frame become 1068 lines. Here, the number shown in each signal indicates the Y scanning line number.

The first field is from line 1 to line 534, the second
The field is from 535 to 1068 lines. Once the video signal of one field is stored in the memory, all the scanning lines of one frame are divided into 12 units by shuffling processing at the time of reading. Two units are sequentially recorded as one segment. After the first segments T1 and T2 are recorded at the same time, T3 and T4, and T5 and T6 are recorded simultaneously and sequentially, respectively, and the recording of one frame is completed by the sixth segments T11 and T12.

As is clear from the above, the signals of all the segments have extremely strong correlation. Thus, passing through the shuffling memory causes a delay of at least one field. In this embodiment, as described later, PCM
One frame is delayed in order to maintain the relationship with the audio delay time.

The reference signals are inserted into the two-channel signals obtained by the above processing by the reference signal insertion circuits 20 and 21, and the D / A
After being converted into analog signals by the converters 22 and 23 and the post filters 24 and 25, the signals are FM-modulated by the FM modulators 26 and 27 to form a video recording signal. The reference signal is used to correct the difference between the level and linearity of the two-channel FM system.
This is a ramp signal disclosed in JP-A-61-46681.

On the other hand, the main audio signal Pin of two channels is
After being band-limited at 1,42, they are digitized by A / D converters 43,44. Switch for normal signal recording
45 and 46 are connected to N side, these signals are voice PCM
The recording signal processing circuit 47 divides the data in units of one field, and in the next one field, performs so-called interleave processing for exchanging the signal arrangement on the time axis and addition of an error correction code.

Further, on the tape recorded by the time axis compression circuit 48, compression is performed so as to be recorded at a position corresponding to the extension of the video track. This results in a one-frame delay.

On the other hand, at the time of copying, the copied PCM audio signal D2in is input to the audio PCM recording signal processing circuit 47 via the switches 45 and 46 connected to the D side. The copied PCM audio signal input is obtained by extracting a signal corresponding to an A / D conversion output during recording from a reproduction signal of another VTR as described later.

The video and audio recording signals formed as described above are switched by the recording signal switch circuit 28 so that the signals are recorded on the tape in the format shown in FIG. In the figure, 92 is a video signal portion, and 93 is a PCM audio signal portion. T1 to T12 are the aforementioned track numbers. The switched signals are recorded amplifiers 29, 30, 31, 32, R
Switch 33,34,3
The data is recorded on the magnetic tape 4 by the magnetic heads 37, 38, 39, and 40 via 5, 36. Hereinafter, the R / P switch is connected to the R side during recording and to the P side during reproduction.

FIG. 6 shows the configuration of the head cylinder. The same applies to the heads of the A1 and B1 channels, which scan the tape almost simultaneously on the tapes of the A2 and B2 channels. The heads A1 and A2 are fixed at 180 degrees from each other, and the same applies to B1 and B2.

FIG. 7 is a diagram for explaining the operation timing when two VTRs are connected as shown in FIG. 1A and copying is performed. First, the operation timing of the recording signal processing system described above with reference to FIG. In the figure, (a) is an input video signal,
Symbols F1 to F7 in the signal (a) are field numbers. (B) is an input audio signal, which is appropriately given a code such as AU-1 corresponding to the upper field number. (C) is a recording video signal. For example, the reference numeral 1-2 indicates the second segment of the field number 1. (D) is the recorded PCM
It is an audio signal. As can be seen from this figure, the video signal and the PCM audio signal are recorded one frame later.

 The above is the operation of the recording system.

 Next, the operation of the reproducing system will be described.

 The reproduction of the video signal is performed as follows.

The video track recorded on the magnetic tape 4 as shown in FIG. 4 is tracked by the magnetic heads 37, 38, 39, and 40, and an electric signal is obtained. Reproduction amplifiers 49, 5 via recording / reproduction mode changeover switches 33, 34, 35, 36 tilted to the P side
After being amplified by 0, 51, 52, A1 corresponding to a position 180 degrees from each other by a reproduction timing changeover switch 53
And A2, B1 and B2 are switched and input to the FM demodulators 54 and 55 to become video signals. These are converted into digital signals by A / D converters 58 and 59 through pre-filters 56 and 57 for A / D conversion on the reproduction side. These are converted into the original arrangement on the time axis by the inverse shuffling memories 60 and 61, and the level correction circuit 62 corrects the imbalance between the gain and the linearity between the channels.

This signal is output as a copy video signal D1out. At the same time, the color signal is time-expanded by the TCI decoder 63, the color is synchronized by interpolating between lines, and the luminance signal is compressed on the time axis to become a signal corresponding to the original time axis. For Y signal, For Cw signal, For Cn signal
D / A converter, 64, 65, 66 and D of Y signal, Cw signal, Cn signal
The analog signals are converted by the / A converter post filters 67, 68, and 69, and the output video signals are Yout, Cwout, and Cnout.

The reproduction of the PCM audio signal is performed as follows. The PCM tracks recorded on the magnetic tape 4 as shown in FIG. 93 in the same manner as the video signals are tracked by the magnetic heads 37, 38, 39, and 40 to obtain electric signals. After being amplified by the reproduction amplifiers 49, 50, 51, 52 via the recording / reproduction mode changeover switches 33, 34, 35, 36 tilted to the P side, the reproduction timing changeover switches 53 correspond to the positions of 180 degrees from each other. The heads A1 and A2, B1 and B2 are switched and converted into digital signals by the binarization circuits 70 and 71, continuous signals by the time base expansion circuit 72, and error correction and deinterleaving by the audio PCM reproduction signal processing circuit 73. This is a two-channel PCM audio signal corresponding to the original time axis. This signal is output as a copied PCM audio signal D2out, and becomes a main audio output signal Pout by the audio signal D / A converters 74 and 75 and the post filters 76 and 77.

Again, the timing of the reproduction signal processing system will be described with reference to FIG. If (c) and (d) are considered as the playback timing of the first VTR, (e) and (f) are the video output signal and the main audio output signal, respectively.

As described above, both video and PCM audio are delayed by one frame during reproduction.

(E) and (f) have substantially the same timing as the copy video signal and copy PCM audio signal transferred from the first VTR to the second VTR, respectively.

Next, recording of the sub audio signal and the time code signal will be described.

The sub audio signal input Lin to be recorded on the linear audio track is input to the analog audio signal delay circuit 78.
Here, it is delayed for a period corresponding to one frame. The data is recorded on a linear track (FIG. 94) on the magnetic tape 4 via an audio recording amplifier 80, a recording / reproducing mode changeover switch 81 connected to the R side, and a linear audio recording / reproducing head 82. Note that the copy sub audio signal input D3in is the same signal as Lin.

The time code signal is generated by the time code generation circuit 84 during normal recording, and the time code recording amplifier 86,
A recording / playback mode switch 87 connected to the R side,
It is recorded on a linear track on the magnetic tape 4 via the time code recording / reproducing head 88. Also, when copying and recording,
The copy time code signal input D4in is input to a time code decoding circuit 85 via a copy mode changeover switch 90 connected to the D side, and the result is added by two frames, and a time code signal corresponding to this time is output to the time code generation circuit 84. The time code recording amplifier 86, R
Recording is performed on a linear track (FIG. 95) on the magnetic tape 4 via a recording / reproduction mode changeover switch 87 and a time code recording / reproduction head 88 connected to the side.

Next, reproduction of the sub audio and the time code signal will be described.

The signal recorded on the linear audio track is output as a sub audio output signal Lout via a linear audio recording / reproducing head 82, a recording / reproducing mode switch 81 connected to the P side, an audio reproducing head 83, and an analog audio signal delay circuit 79. Is done. The copy sub audio signal output D3out is the same signal as Lout.

The signal recorded on the time code track is transmitted to a time code recording / reproducing head 88, a recording / reproducing mode switch 87 connected to the P side, a time code reproducing amplifier 89, N
It is decoded by a time code decoding circuit 85 via a copy mode changeover switch 90 connected to the side, and is output as a time code output signal Tout. The time code copy output signal D4out is the same signal as T4out.

FIG. 7 shows the timing of the copy signal and the signal recorded on the linear track. (G) is a copied video recording signal recorded by the second VTR, (h) is a copied PCM audio recording signal recorded by the second VTR, and (i) is a sub audio recording recorded by the first VTR. Signal, (j) is a sub-audio reproduction output signal of the first VTR and a copy sub-audio signal transferred from the first VTR to the second VTR, and (k) is a copy sub-audio signal recorded by the second VTR. An audio recording signal, (1) is a time code recording / reproducing signal of the first VTR, a time code output signal, a time code copy output signal, and (m) is a time code copy recording signal recorded by the second VTR. In the figure, the numbers attached to the time codes are so-called SMPTE time codes, which are relative values in frame units.

The delay time of the signal recorded on the linear track is
The present invention is not limited to the above embodiment, and it is sufficient if the total number of frames on the recording side and the reproducing side is two. Therefore, for example, the time code signal may be delayed by one frame during reproduction, and may be delayed by one frame by the microcomputer.

When two VTRs with such a configuration are connected and copied as shown in Fig. 1 (a), the video signal requires minimal image quality deterioration, and the audio signal can be copied after error correction. ,
No matter how many times the copying is performed, the relative time of all the signals including the analog audio signal and the time code signal recorded on the linear track is kept forever, so that there is no inconvenience caused by editing. In this embodiment, the output of the copy video signal is supplied from the output of the level correction circuit. This is because the error can be prevented from accumulating by transmitting and receiving a signal in which an error between channels generated for each VTR is compensated.

Similarly, in order to prevent the resolution of the color signal in the vertical direction from being degraded by performing the vertical filter processing for the color line sequential each time the copy is performed, the copy reproduction side is performed before the color simultaneous and the copy recording side is performed the color line sequential. Later, a copy signal is transmitted and received.

According to the present invention, so-called copying is performed in which an analog recording magnetic recording / reproducing apparatus which once digitizes and handles a video signal reproduces a signal from one magnetic recording / reproducing apparatus and records the signal on the other magnetic recording / reproducing apparatus. In this case, by performing transmission and reception using digital signals, signal deterioration due to repetition of A / D and D / A conversions can be avoided, and good copy characteristics can be obtained. Furthermore, since the PCM audio signal can be copied after error correction, no error accumulation due to copying occurs. Also, accumulation of errors between channels and deterioration of the vertical resolution of color signals do not occur. Also, no matter how many times the copying is performed, the relative time of all the signals including the analog audio signal and the time code signal recorded on the linear track is preserved forever, so that there is no inconvenience caused by editing.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an embodiment of a signal copying method according to the present invention, FIG. 2 is a block diagram illustrating the configuration of a magnetic recording / reproducing apparatus according to the present invention, FIG. 3 is a waveform diagram illustrating the operation of a TCI encoder, FIG. 4 is an explanatory diagram of the shuffling process, FIG. 5 is a tape format, FIG. 6 is a plan view showing the configuration of the head cylinder, and FIG. 7 is a timing diagram for explaining the timing of the recording and reproduction signal processing. . 10,12,14,43,44,58,59 …… A / D converter, 22,23,64,65,66,
74,75 ... D / A converter, 15 ... TCI encoder, 63 ... TCI
Decoder, 18, 19… Shuffling memory, 60, 61… Reverse shuffling memory, 47… PCM recording signal processing circuit, 73…
... PCM playback signal processing circuit.

Continuation of the front page (72) Inventor Shigeru Awamoto 1006 Kazuma Kadoma, Kazuma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (58) Field surveyed (Int. Cl. ⁶ , DB name) H04N 5/91-5 / 956 H04N 9/79-9/898 G11B 5/027

Claims (8)

(57) [Claims] A first magnetic recording / reproducing device for reproducing an analog video signal in which a time-axis-compressed chrominance signal is multiplexed with a luminance signal on a time axis, and a step of digitizing the reproduced analog video signal Transferring the digital signal to a second magnetic recording / reproducing device;
Recording the transferred digital signal as an analog signal in a second magnetic recording / reproducing apparatus. 2. A video signal recorded on the first and second magnetic recording / reproducing devices is a signal of a plurality of channels in which a color signal compressed on a time axis and a luminance signal expanded on a time axis are multiplexed on a time axis. 2. The signal copying method according to claim 1, wherein 3. The color signals recorded in the first and second magnetic recording / reproducing devices are line-sequential, and the signals transferred from the first magnetic recording / reproducing device are those before the line synchronization processing. 3. The signal copying method according to claim 2, wherein: 4. A video signal recorded in each of the first and second magnetic recording / reproducing devices has a level reference signal inserted therein, and a signal transferred from the first magnetic recording / reproducing device undergoes level correction processing. 2. The signal copying method according to claim 1, wherein the signal is output after the processing is performed. 5. The first and second magnetic recording / reproducing devices record an input audio signal and a video signal by dividing the input audio signal and the video signal at substantially the same cycle, and then changing the arrangement order on the time axis within the interval. A magnetic recording / reproducing apparatus for forming and recording an analog signal and a recording PCM audio signal, wherein a PCM audio signal among signals transmitted from a first magnetic recording / reproducing apparatus is subjected to error correction, and then converted into a digital signal in the form of a digital signal. 2. The signal copying method according to claim 1, wherein the signal is transferred in the form of a digital signal after being returned to the original arrangement. 6. A magnetic recording / reproducing apparatus for recording an analog audio signal together with an analog video signal and a PCM audio signal, wherein the first and second magnetic recording / reproducing apparatuses record analog audio signals of the first magnetic recording / reproducing apparatus. 2. The signal copying method according to claim 1, wherein an analog audio signal obtained by delaying the signal by a predetermined time is recorded in the second magnetic recording / reproducing apparatus. 7. A magnetic recording / reproducing apparatus for recording a time code signal together with an analog video signal and a PCM audio signal, wherein the first and second magnetic recording / reproducing apparatuses record the time code of the first magnetic recording / reproducing apparatus. 6. The signal copying method according to claim 5, wherein a time code signal obtained by delaying the signal by a predetermined time is recorded in the second magnetic recording / reproducing apparatus. 8. A means for reproducing an analog video signal in which a time-axis-compressed color signal is multiplexed on a time axis with a luminance signal;
A magnetic reproducing apparatus including at least means for digitizing the reproduced signal to a digital signal, means for outputting and transferring the digital signal, transfer input means for inputting the transferred digital signal, and transfer input means A signal copying apparatus comprising a magnetic recording device having at least means for converting the digital signal input to the means into an analog signal, and means for recording the output of the converting means.