JP2508121B2 - Recording and playback device - Google Patents

Description

The present invention relates to a recording / reproducing apparatus, and more specifically to a recording / reproducing apparatus capable of simultaneously recording and reproducing input signals of a plurality of systems.

[Conventional technology]

Since the original digital signal can be completely restored if the reproduction S / N level is a certain value or more, the digital signal is attracting attention for high-quality recording / reproduction. For example, an analog video signal is subjected to digital pulse modulation. Digital video recording is performed in which the resulting digital video signal is recorded on a magnetic tape, a magnetic disk, or an optical disk. In a digital VTR that digitally records a video signal on a magnetic tape, the digital video signal is recorded at a track pitch that allows a minimum allowable S / N.
The long-term recording mode realized by the current analog recording / reproducing VTR is dealt with by reducing the digital data (bandwidth compression).

Recent advances in digital recording / playback and band compression technologies are remarkable, and playback images that are sufficiently satisfactory can be obtained even in the long-time mode. From the viewpoint of effective use of magnetic tape, the long-time mode has come to be used frequently. Is coming.

[Problems to be solved by the invention]

With the spread of VTR, programs are created with the intention or premise of video recording, and there is a demand for recording a plurality of programs in the same time zone. But,
If you want to record two programs in overlapping time zones,
Currently, two VTRs are required.

Therefore, the present invention focuses on the fact that high-density recording is possible in the digital recording / reproducing system and the reproduced signal quality is sufficiently high for viewing, and recording / reproducing of one system of signals and simultaneous reproduction of plural systems of signals. An object of the present invention is to provide a recording / reproducing apparatus that enables recording / simultaneous reproduction by using the same recording / reproducing unit.

[Means for solving problems]

A recording / reproducing apparatus according to the present invention is an apparatus for forming a large number of tracks on a recording medium to record / reproduce signals, and records and reproduces a signal of one system at a predetermined rate on each of the plurality of tracks. The first mode in which the generated signal is output as a signal of one system, and the signal of n (n is an integer of 2 or more) system is compressed to generate a compressed signal of 1 / n of the predetermined rate. When recording the compressed signal of the system, one compressed signal of the compressed signals of the n systems is selectively recorded for each of the plurality of tracks, and the reproduced signals of the n system are expanded respectively. Second to output
And a mode of.

[Action]

According to the above configuration, the recording and reproducing rates are the same in both the first mode and the second mode.
By using the recording / reproducing unit of the conventional high-density recording / reproducing apparatus, simultaneous recording of a plurality of video signals becomes possible. Further, it becomes possible to simultaneously reproduce and output the signals for simultaneous recording.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 shows a recording / reproducing system capable of simultaneously recording and reproducing two systems of video signals.

First, the standard mode will be described. In this mode, switches 22 and 58 connect to the a contacts. Analog video signal input to the input terminal 10A is the A / D converter 12A 4f _SC (f _SC
Is sampled at the NTSC color subcarrier frequency,
It is converted into an 8-bit digital signal. The sub-sampling circuit 14A decimates the output of the A / D converter 12A with a field offset or a line offset, compresses it into a signal having a sampling rate of 2f _SC , and supplies it to the a contact of the switch 22. The distribution circuit 24 distributes the signal from the switch 22 into two systems. The signals distributed to the two systems by the distribution circuit 24 are supplied to the switches 30A and 30B via ECC encoding circuits 26A and 26B and modulation circuits 28A and 28B, respectively. ECC encoding circuit 26
A and 26B perform processing such as addition of error detection / correction code and interleaving, and modulation circuits 28A and 28B convert the signal into a signal having a small DC component suitable for digital recording.

In the standard mode, the switches 30A and 30B alternately switch to the a contact and the b contact at a cycle of 1/120 second. Signal is recording amplifier 3
It is amplified by 2, 33, 34, 35 and magnetically recorded on the magnetic tape 40 by the magnetic heads 36, 37, 38, 39. The arrangement of the magnetic heads 36 to 39 is shown in FIG. In FIG. 2, reference numeral 72 designates a rotary head drum. 2A is a plan view of the rotary drum 72 seen from above, and FIG. 2B is a layout view of the heads 36 to 39 seen from the side of the drum 72. The heads 36 and 37 constitute a pair head, the head 36 is + azimuth, and the head 37 is −azimuth. As shown in FIG. 2 (b), its height is 1 track pitch (T _P ) Minutes differ. Head 38, 39 is also head 3
It has the same relationship as 6,37, and these two pair heads
Opposite at 180 degree intervals. The rotating head drum 72 has 3,6
Rotating at 00 rpm, the magnetic tape 40 is wound around its outer periphery over about 180 °. Therefore, in the standard mode, as shown in FIG. 3A, one field of a video signal having a field frequency of 60 Hz is recorded on four tracks.

A case where the video signal recorded in the standard mode is reproduced will be described. Magnetic tape 40 with magnetic heads 36-39
The signal reproduced from is applied to the switches 48A and 48B via the reproduction amplifiers 44 to 47. The switches 48A and 48B are switched between the a contact and the b contact at a 1/120 second cycle as in the recording. The detection circuits 50A and 50B are composed of a waveform equalizer, a clock regenerator, and a discriminator. By comparing the voltages at the bit times obtained from the clock regenerator, the discriminator compares "0" and "1". Determine. Demodulator 52A, 52B detection circuit 50
The outputs of A and 50B are demodulated, and ECC decoding circuits 54A and 54B perform error detection / correction and deinterleave processing. The synthesis circuit 56
The outputs of the ECC decoding circuits 54A and 54B are combined and output as a single system signal. In the standard mode, the switch 58 is connected to the contact a, and the output of the synthesis circuit 56 is converted into an analog signal by the D / A converter 68A after the thinning sample points are interpolated by the interpolation circuit 66A, and output terminal 70A. Is output from.

Next, the operation in the long time mode will be described. In this mode, switches 22 and 58 connect to the b contacts. Input terminal 10A
The analog video signal of is subjected to the same processing as that in the reference mode in the A / D converter 12A and the sub-sampling circuit 14A, and is applied to the scale / index (S / I) encoding circuit 16A.
The S / I encoding circuit 16A is a circuit for performing scale / index encoding, and the MIN-MAX method is generally famous. This MIN-MAX method divides an image into blocks and equally divides the maximum value and the minimum value in each block for quantization. The quantization representative value can be reproduced on the receiving side by transmitting the index indicating which quantization level each pixel belongs to, and further transmitting the maximum value and the minimum value as the scale component.

For example, 16 (= 4 x 4) pixels are set as one block, the maximum value and the minimum value are each 8 bits as a scale component, and all 16 pixels are assigned a 3-bit index obtained by dividing the maximum value and the minimum value into eight. As a result, the amount of information of 128 bits / block when all 16 pixels are quantized with 8 bits,
Half of 64 (= 2x8 + 16x3) bits / block is enough.

The signal whose data amount has been halved by the S / I encoding circuit 16A is time-axis compressed by the time-axis conversion circuit 18 during the period shown in FIG. 6 (3) and applied to the distribution circuit 24 via the b contact of the switch 22. To be done. The distribution circuit 24 distributes the input signal to two signal processing systems. The ECC encoding circuits 26A and 26B perform processing such as addition of error detection / correction code and interleaving on the output of the distribution circuit 24, and intermittently output according to the recording rate. For example, assuming that the number of revolutions of the head drum 72 is constant at 3,600 rpm, the signal output at the timing shown in FIG. 6 (1) in the standard mode is shown in FIG. 6 (2) in the long time mode. Thus, it is output intermittently and is recorded only by a pair of heads consisting of heads 36 and 37. Modulation circuit 28A, 28
B modulates the outputs of the ECC encoding circuits 26A and 26B in the same manner as in the standard mode and applies it to the switches 30A and 30B.

The switches 30A and 30B repeat connection / non-connection at a 1/60 second cycle in accordance with the output timing of the ECC encoding circuits 26A and 26B. The signals at the a contacts of the switches 30A and 30B are applied to the magnetic heads 36 and 37 via the recording amplifiers 32 and 33 and recorded on the magnetic tape 40.

Further, in the long time mode, the capstan motor 42 rotates at half the speed in the standard mode according to an instruction from the system controller 44, and the recording format on the magnetic tape 40 is shown in FIG. ), When reproducing the recording signal in such a long time mode, only the heads 36 and 37 are used, and the reproduction signal is transmitted via the reproducing amplifiers 44 and 45 to the switch 48A, 48B a. It is applied to the contacts and supplied to the combining circuit 56 via the detection circuits 50A and 50B, the demodulation circuits 52A and 52B, and the ECC decoding circuits 54A and 54B, respectively. In the ECC decoding circuits 54A and 54B, the time axis is converted after error detection / correction and deinterleave processing are performed.
The signals made continuous by the synthesizing circuit 56 are applied to the time axis expanding circuit 62 via the b contact of the switch 58, and the time axis expanding is performed there. The scale / index decoding circuit 64A decodes the output data of the time axis expansion circuit 62 into a representative value of 8 bits per sample, performs block raster conversion, and outputs it. The interpolation circuit 66A interpolates the data thinned out by the sub-sampling circuit 14A. The D / A converter 68A converts the output of the interpolation circuit 66A into an analog signal and outputs it to the output terminal 70A.

Next, a two-system input recording mode for simultaneously recording two-system input signals will be described. In this mode, switches 22 and 58 are connected to the C contacts. The video signal input to the input terminal 10A is processed by the A / D converter 12A, the sub-sampling circuit 14A and the S / I encoding circuit 16A in the same manner as in the long-time mode, and then supplied to the synthesizing circuit 20. To be done. The video signal input to the input terminal 10B is the A / D converter 12B and the sub-sampling circuit 14B.
And the S / I encoding circuit 16B, the same processing as the video signal of the input terminal 10A is performed, and then the composite signal is supplied to the synthesis circuit 20. The synthesis circuit 20 is composed of a time axis conversion circuit and a switching circuit,
Combine both inputs. The combined signal has the same data rate as in the standard mode, and the distribution circuit 24 and the subsequent processes are subjected to the same processing as in the standard mode.

The pair heads 36 and 37 are supplied with the video signal of the input terminal 10A, and the pair heads 37 and 38 are supplied with the video signal of the input terminal 10B.
_{T 1 ~T 2, T 3 ~T} 4 period (sixth diagram signal is not supplied, ...
() Is time-compressed with the signal from the input terminal 10B, and the signal from the input terminal 10A shown in FIG. 6 (2) and the signal from the input terminal 10B shown in FIG. 6 (3) are switched to each other. The signal having the standard mode data rate shown in 1) is used. The recording format of the magnetic tape is the same as in the standard mode as shown in FIG.

The time of reproduction will be described. The same processing as in the standard mode is performed on the heads 36 to 39 to the combining circuit 56. The output of the combining circuit 56 is supplied to the distribution circuit 60 via the c contact of the switch 58. The distribution circuit 60 is composed of a switching circuit and a time axis conversion circuit. The reproduction signals from the heads 36 and 37 are output to the time axis conversion circuit 62, and the reproduction signals from the heads 38 and 39 are expanded in the time axis to S / I. Output to the decoding circuit 64B. The S / I decoding circuit 64B, the interpolation circuit 66B, and the D / A converter 68B perform the same processing as in the long-time mode, and output the output terminal 70B. The signal expanded by the time axis conversion circuit 62 is processed by the S / I decoding circuit 64A, the interpolation circuit 66A and the D / A converter 68A in the same manner as in the long time mode, and is output to the output terminal 70A.

FIG. 4 shows a digital VTR 80 which is an embodiment of the present invention.
Fig. 5 shows an example in which two tuners or cameras 81, 82 are connected as input devices and two monitor devices 83, 84 are connected as output devices. Fig. 5 is an example in which one monitor device 83 is connected as an output device. Indicates. The digital VTR80 is operated in the dual system input mode and the two input signals are recorded on the magnetic tape. As the reproduction mode, in the case of FIG. 4, the two-system reproduction mode is set, and each reproduction image is displayed on the two monitor devices 83 and 84. In the case of FIG. 5, one playback device can be displayed by connecting one monitor device 83 to either of the playback output terminals 70A and 70B of the digital VTR 80.
Playback video on the target side can be displayed by switching the output terminal to be connected. Further, the monitor device 83 is connected to the output terminal 70A of FIG. 1 so that either the reproduction signals of the heads 36 and 37 and the reproduction signals of the heads 38 and 39 are selectively or alternately selected.
By controlling the distribution circuit 60 via the system controller 44 so as to supply to 62, two outputs can be selected by one monitor device.

The present invention is not limited to the above-described embodiment, and it is possible to input n systems of data band-compressed to 1 / n with respect to the maximum recording rate.

〔The invention's effect〕

As can be seen from the above description, according to the present invention, it is possible to obtain an apparatus capable of performing the best recording / reproducing of an input signal of a plurality of systems and an input signal of a single system using the same recording / reproducing unit. You can

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, FIG. 2 is a layout diagram of a reproducing / recording head, FIG. 3 is a diagram showing a recording track pattern of a magnetic tape, and FIGS. 4 and 5 are FIG. 6 is a diagram showing the relationship between the heads involved in recording / reproduction and the signal processing timing, as an example of the configuration of input and output by the device of the present invention. 10A, 10B …… Input terminal, 16A, 16B …… Scale / index coding circuit, 18,62 …… Time axis conversion circuit, 26A, 26B…
… Error detection / correction circuit, 36 …… Head A +, 37 …… Head A–, 38 …… Head B +, 39 …… Head B−, 44 ……
System controller, 64A, 64B ... Scale / index recovery circuit, 70A, 70B ... output terminals

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinsuke Yamashita 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Shin Mamoru Shimogoriyama 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Souichi Kashida 770 Shimonoge, Takatsu-ku, Kawasaki City, Kanagawa Canon Inc. Tamagawa Plant (56) Reference JP-A-61-77104 (JP, A) JP-A-62- 3467 (JP, A)

Claims (1)

(57) [Claims] 1. An apparatus for recording and reproducing signals by forming a large number of tracks on a recording medium, wherein one system of signals at a predetermined rate is recorded on each of the plurality of tracks and reproduced signals are recorded. A first mode for outputting as a signal of one system, and a signal of n (n is an integer of 2 or more) system is compressed to generate a compressed signal of 1 / n of the predetermined rate, and the compressed signal of the n system. A second compressed signal for selectively recording one of the n compressed signals for each of the plurality of tracks, and expanding and outputting the reproduced n signals. And a recording / reproducing apparatus.