JP3428543B2 - Digital information recording device, reproducing device and method thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to digital information recording.
The present invention relates to an apparatus, a reproducing apparatus and a method thereof , and particularly to bit compression.
The present invention relates to a digital information recording apparatus, a reproducing apparatus, and a method for recording and reproducing the digital information transmitted and transmitted.

[0002]

2. Description of the Related Art Conventionally, a device for compressing, modulating and transmitting an information signal and receiving the transmitted signal is, for example,
It is described in JP-A-63-28143. This publication describes a technique in which a packet transmission technique is adopted and a program of a certain time unit is shortened to be broadcast in a short time, and the receiving side expands the program in real time for reproduction and listening.

The Television Society, Vol. 37, No. 5
No. 366-374 (May 1983), a commentary article entitled "Audio Signal System for Satellite Television Broadcasting" is published. In this explanation article, the audio signal is 14 /
Compress based on the 10-bit quasi-instantaneous companding (5 range) rule,
Described is an audio signal system of television broadcasting in which four-phase DPSK (Differential Phase Shift Keying) is performed for transmission and the transmission signal is received.

[0004]

However, bit compression is not possible.
There is no description of a digital information recording / reproducing apparatus that records / reproduces digital information transmitted and transmitted.

An object of the present invention, the digital information recording for recording and reproducing digital information transmitted is bit compressed
An object is to provide an apparatus, a reproducing apparatus, and a method thereof .

[0006]

In order to achieve the above-mentioned object, the present invention comprises the following means.

[0007]

A digital information recording / reproducing apparatus according to the present invention receives bit-compressed digital information which is error-corrected based on a transmission parity signal which is time-axis converted and added to bit-compressed digital information. A parity signal adding means for adding a recording parity signal different from the transmission parity signal, and a recording / reproducing operation for recording / reproducing the compressed digital information to which the recording parity signal has been added by the parity signal adding means on a recording medium. Means and the recording time by the recording / reproducing means, the time axis conversion
According to the length, and the playback time is canceled by the time axis conversion.
Control means for controlling the recording / reproducing means to have a length, error correcting means for error correcting the compressed digital information reproduced by the recording / reproducing means on the basis of the recording parity signal, and error correction by the error correcting means. And bit expansion means for expanding the compressed digital information corresponding to the bit compression. Further, the digital information recording / reproducing method according to the present invention is such that the transmission parity added to the time-axis-converted and bit-compressed digital information.
Receiving bit-compressed digital information that has been error-corrected based on the signal , a recording parity different from the transmission parity signal.
Adding I signals recorded on a recording medium, and reproducing the bit compressed digital information from the recording medium, the recording Paris
A digital information recording / reproducing method in which error correction is performed based on a T. signal , and bit expansion is performed in correspondence with the bit compression, wherein a recording time on the recording medium corresponds to the time axis conversion.
And the playback time is the length when the time axis conversion is canceled.
It controls to become .

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described based on examples with reference to the drawings.

FIG. 1 is a block diagram of a digital information receiving / recording / reproducing apparatus including a digital information recording / reproducing apparatus of an embodiment of the present invention. FIG. 2 is a block diagram of an embodiment of a digital information transmitting apparatus for transmitting a transmission signal toward FIG.

First, the digital information transmitter of FIG. 2 will be described. In FIG. 2, 1 is a magnetic tape, 2 and 3
Is a magnetic head, 4 is a cylinder, 5 is a capstan, 10
Is a servo control circuit, 20 is a demodulation circuit, 21 is an error correction circuit, 22 and 23 are compression circuits, 130 is a control signal generation circuit, 24 is a parity addition circuit, 25 is a modulation circuit, 26 is a transmission circuit, and 27 is a transmission line. Is.

The digital video signal and audio signal recorded on the magnetic tape 1 are reproduced by the magnetic heads 2 and 3 mounted on the cylinder 4 and input to the demodulation circuit 20. The magnetic tape 1 is run by the capstan 5. Magnetic tape 1
The traveling speed and the rotation frequency of the cylinder 4 are, for example, 10 times higher than usual. Therefore, the signal input to the demodulation circuit 20 is time-compressed ten times. For example,
If a 120-minute signal is recorded on the magnetic tape, it can be reproduced in 12 minutes.

Generally, when a digital signal is recorded on a magnetic recording medium, it is recorded after being modulated into a scrambled NRZ, M2 code or the like. In the demodulation circuit 20, signal processing for returning the thus-modulated signal to the original digital data, that is, demodulation is performed. Demodulation circuit 20
The signal demodulated in (4) is input to the error correction circuit 21, and erroneous data is detected and corrected in the magnetic recording / reproducing process.

Further, the video signal and the audio signal are separated,
Input to the compression circuits 22 and 23, respectively. The video signal is bit-compressed by the discrete cosine transform (DCT). The audio signal is bit-compressed by nonlinear quantization, differential PCM, or the like. As a result, the total transmission rate of the video signal and the audio signal is reduced to, for example, 1/20.

The output signals of the compression circuits 22 and 23 are input to the parity adding circuit 24. The control signal from the control signal generation circuit 130 is also input to the parity adding circuit 24. Here, the control signal includes at least a control signal for controlling the operation of the recording / reproducing apparatus as described later. The parity adding circuit 24 adds a parity signal for error correction for correcting an error that occurs during transmission, and performs signal processing such as serially outputting a video signal and an audio signal according to the transmission format. The output signal of the parity addition circuit 24 is input to the modulation circuit 25. The modulation circuit 25 modulates the serial signal according to the characteristics of the transmission line 27 and the frequency band. In this case, the transmission path 27 is a space, and for example, when transmitting by radio waves, the modulation circuit 25 performs modulation by quadrature phase modulation (QPSK). The modulated signal is input to the transmission circuit 26 and output to the transmission line 27 as a transmission signal. In this way, the signal can be transmitted at a speed 10 times faster than usual.

In the above embodiment, the case where the signal is reproduced from the VTR has been described, but the signal source is not limited to the VTR, and may be a magnetic disk device, an optical disk device or the like.

Next, a digital information receiving / recording / reproducing apparatus including the digital information recording / reproducing apparatus of the embodiment of the present invention shown in FIG. 1 will be described. In FIG. 1, 27 is a transmission line, 3
0 is a receiving circuit, 31 is a demodulation circuit, 32 is an error correction circuit,
Reference numeral 82 is a memory circuit, 80 is a changeover switch, 62 is an expansion circuit, 64 is a D / A conversion circuit, 70 is a video signal output terminal, and 131 is a control circuit.

The transmission signal transmitted from the digital information transmitting apparatus of FIG. 2 to the transmission line 27 is received by the receiving circuit 30. The received signal is input to the demodulation circuit 31.
The demodulation circuit 31 corresponds to the modulation circuit 25 of FIG. 2 and demodulates to the original signal.

The demodulated signal is input to the error correction circuit 32, and the error generated in the transmission line 27 is detected and corrected based on the error correction parity signal added by the parity addition circuit 24 in FIG. At this time, if the S / N of the transmission system is insufficient and the error cannot be corrected, the correction is performed by replacing the signal using the correlation of the signal.

The error-corrected video signal output from the error correction circuit 32 is input through the memory circuit 82 to the terminal R side selected at the time of recording by the changeover switch 80. The memory circuit 82 has a memory capacity of at least one field, and a video signal received at high speed is stored in the memory at each frame, read from the memory at a regular speed, and input to the decompression circuit 62.

The decompression circuit 62 corresponds to the compression circuit 22 of FIG. 2 and bit-decompresses the compressed video signal corresponding to the discrete cosine transform (DCT) to restore the original video signal. It The output signal is the D / A conversion circuit 6
4 is input to the input terminal 4, converted from a digital video signal to an analog video signal, and output from the output terminal 70.

The error-corrected control signal output from the error correction circuit 32 is detected by the control circuit 131, so that the operation of the recording / reproducing apparatus, for example, the start of recording can be controlled.

Further, in FIG. 1, 33 is a parity adding circuit, 34 is a modulating circuit, 40 is a magnetic tape, and 41, 42.
Is a magnetic head, 43 is a cylinder, 44 is a capstan,
50 is a servo control circuit, 60 is a demodulation circuit, 61 is an error correction circuit, 63 is an expansion circuit, 65 is a D / A conversion circuit, 71
Is an output terminal of an audio signal.

The output signal of the error correction circuit 32 is input to the parity addition circuit 33. The parity adding circuit 33 adds a parity signal for detecting and correcting an error that occurs during recording and reproduction. The signal to which the parity is added is input to the modulation circuit 34. In the modulation circuit 34,
Modulate to a code suitable for magnetic recording. For example,
These include scrambled NRZ and M2 codes. The modulated signal is transmitted to the magnetic heads 41, 4 mounted on the cylinder 43.
2 is recorded on the magnetic tape 40.

At this time, since the signal is time-compressed ten times as much as usual, the rotation frequency of the cylinder 43 and the running speed of the magnetic tape 40 are made ten times as much as usual.
The servo control circuit 50 controls the rotation of the cylinder 43 and the capstan 44.

Further, in order to record a predetermined signal at a predetermined position on the magnetic tape 40, synchronization information is detected from the received signal, and the rotation phase control of the cylinder 41 is performed based on the synchronization information.

Next, the operation of reproducing the signal thus recorded will be described. During reproduction, the running speed of the magnetic tape 40 and the rotation frequency of the cylinder 43 are set as if they were normal reproduction. The reproduced signal is input to the demodulation circuit 60. The demodulation circuit 60 corresponds to the modulation circuit 34, demodulates the modulated signal and outputs it.
The demodulated signal is input to the error correction circuit 61, and the error is detected and corrected based on the parity signal in which the error generated in the magnetic recording / reproducing system is added by the parity adding circuit 33.
Also, the video signal and the audio signal are separately output.

It is inputted to the expansion circuit 62 via the video signal changeover switch 80. The decompression circuit 62 corresponds to the compression circuit 22 of FIG. 2, and the compressed video signal is restored to the original video signal by the decompression circuit 62. The output signal is input to the D / A conversion circuit 64, converted from digital to analog video signal, and output from the terminal 70.

The audio signal is input to the expansion circuit 63.
The decompression circuit 63 corresponds to the compression circuit 23 of FIG. 2, and the compressed audio signal is restored to the original audio signal by the decompression circuit 63. The output signal is the D / A conversion circuit 6
5 is input, converted from a digital audio signal into an analog audio signal, and output from a terminal 71.

In the embodiment shown in FIG. 1, the error correction circuit 32
The output video signal is input to the expansion circuit 62 via the memory circuit 82, but the output signal of the modulation circuit 34 may be input to the demodulation circuit 60 via the memory circuit. Further, if the demodulation circuit 60 and the error correction circuit 61 have a sufficient operating speed, a memory circuit may be added afterward, or the error correction circuit 61 and the decompression circuit 62 have a sufficient storage capacity. If so, the memory circuit may be omitted by using it.

In the embodiment shown in FIGS. 2 and 1, parity is added to detect or correct an error occurring in the transmission system or the magnetic recording / reproducing system. As an example of a method of adding parity, a magnetic recording / reproducing apparatus in the D2 format, that is, D
The case of a 2-format VTR is shown in FIG. D2
In the format VTR, the signal of one field is divided into a plurality of segments for signal processing, but in FIG.
It shows one of the segments.
In FIG. 3, 90 is a video data group, 91 is an outer code parity group, and 92 is an inner code parity group. First, the outer code parity is added to the data arranged vertically in the figure of the video data group 90 arranged in a matrix. After that, the video data group 90 and the outer code parity group 9
In FIG. 1, a recording signal is generated with the inner code parity added to the data arranged in the horizontal direction. The generation of the parity is made according to the generator polynomial G (x), which will not be described in detail here.

In the embodiments shown in FIGS. 2 and 1, if the parity adding circuits 24 and 33 generate the same parity, most of the error correcting circuits 32 and 61 can be shared. That is, since the error correction circuits 32 and 61 are circuits used at the time of recording and at the time of reproducing, respectively, by sharing them,
The circuit scale can be reduced.

Although not described in the above embodiments, such a helical scan type magnetic recording / reproducing apparatus, that is, a VTR.
In this case, since the signal becomes discontinuous when the track is jumped during reproduction, an amble signal is added to the beginning of the signal for recording. Since the addition of the amble signal is also performed in the D2 format VTR, the detailed description thereof will be omitted. Also, to determine the starting position of the signal,
Although a synchronization signal is appropriately added, a detailed description thereof will be omitted because it is a known technique in the D2 format VTR.

In the embodiment shown in FIG. 2, it can be considered that the amble signal is added by the parity adding circuit 24. Alternatively, it may be performed on the recording / reproducing apparatus side in order to improve the use efficiency of the transmission path 27. Also in this case, it may be considered that the amble signal is added by the parity adding circuit 33. If the amble signal is added on the side of the digital signal transmitting device, when the signals are simultaneously transmitted to a large number of recording / reproducing devices, that is, VTRs, the VTR can be reduced in price and its effect can be enhanced.

As an application example of the present invention, a signal can be transmitted from a digital signal transmitting device to a large number of recording / reproducing devices, that is, VTRs simultaneously and at high speed through a transmission path. At this time, it is difficult to control a large number of VTRs at the same time, and it is also necessary to control which VTR is recorded and which VTR is not recorded. A technique for realizing such control will be described below.

For that purpose, a control signal is transmitted when transmitting a digital signal to be recorded.

An example of the control signal is shown in FIG. In FIG. 4, 110 is a synchronizing signal, 111 is an ID signal indicating what kind of control is to be performed, 112 is an address signal indicating which VTR is to be controlled, and 113 is a recording mode of the VTR designated by the address signal 112. , 114 is a control signal for stopping recording, 115 is a control signal for stopping recording,
Reference numeral 116 is a blank signal, and 120 is a signal to be actually recorded.

An address signal 11 indicating to which VTR a signal is recorded at a predetermined position with respect to the synchronization signal 110.
ID signal 111 indicating that 2 is to be transmitted, and each V
Put TR in standby. When all the address signals have been transmitted, by transmitting the ID signal 113, recording of the recording signal 120 on the designated VTR can be started. After transmitting the recording signal 120, the ID signal 114 for controlling the recording stop is transmitted. Signals 115,116
Is a blank signal, which is a signal portion that is insignificant in terms of matching the signal transmission format with other portions.

In the embodiment shown in FIG. 2, these control signals are generated by the control signal generation circuit 130, and the parity addition circuit 24 adds a parity signal for correcting an error occurring during transmission and transmits the parity signal.

In the digital signal receiver shown in FIG. 1,
The receiving circuit 30 receives the signal, the demodulating circuit 31 demodulates it, and the error correcting circuit 32 corrects an error that occurred during use, and then the control circuit 131 detects a control signal to record and stop the recording / reproducing apparatus. Control.

As described above, a large number of VTRs can be selectively and simultaneously controlled by using the applied embodiment.

[0041]

As described above, according to the present invention,
It is possible to provide a digital information recording apparatus, a reproducing apparatus, and a method for recording / reproducing digital information that has been bit-compressed and transmitted.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a digital information receiving / recording / reproducing apparatus including a digital information recording / reproducing apparatus of an embodiment of the present invention.

FIG. 2 is a block diagram of a digital information transmitting device.

FIG. 3 is a diagram showing a conventional parity addition method.

FIG. 4 is a diagram of control signals.

[Explanation of symbols]

33 ... Parity addition circuit 34 ... Modulation circuit 40, 41, 42, 43, 44, 50 ... Recording means 50 ... Servo control circuit 60 ... Demodulation circuit 61 ... Error correction circuit 63 ... Decompression circuit

Front page continued (72) Inventor Keizo Nishimura, 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa, Ltd. Home Appliances Research Laboratory, Hitachi, Ltd. (72) Inventor, Yuzumi Wataya, 292 Yoshida-cho, Totsuka-ku, Yokohama, Kanagawa Home Appliances Research Laboratory, Hitachi, Ltd. (72) Akira Shibata, 292 Yoshida-cho, Totsuka-ku, Yokohama, Kanagawa Prefecture, Ltd. Home Appliances Research Laboratory, Hitachi, Ltd. (56) Reference JP-A-2-14619 (JP, A) JP-A-64 −73560 (JP, A) The Institute of Electronics, Information and Communication Engineers, Electronic Information and Communication Handbook Second Volume, Japan, Ohmsha, Ltd., March 30, 1988, 1st edition, 1st edition, page 2579 (58) Fields investigated ( Int.Cl. ⁷ , DB name) G11B 20/10-20/16 351

Claims (6)

(57) [Claims] 1. A received a bit compressed digital information subjected to error correction based on the time axis converted and transmitted parity signal added to the digital information bits compressed, the heat transfer
Parity signal adding means for adding a recording parity signal different from the transmission parity signal, and recording / reproducing means for recording / reproducing the compressed digital information added with the recording parity signal by the parity signal adding means on / from a recording medium. , The recording time by the recording / reproducing means is adapted to the time axis conversion.
And the playback time is the length when the time axis conversion is cancelled.
And control means for controlling said recording and reproducing means so that the error correction means for error correction on the basis of the recording parity signal compressed digital information reproduced by said reproducing means, error corrected by the error correction means A digital information recording / reproducing apparatus, comprising: a bit expanding means for expanding compressed digital information corresponding to the bit compression. 2. A digital information recording apparatus for recording digital information on a recording medium for reproduction by a digital information reproducing apparatus, which is based on a transmission parity signal added to time axis converted and bit compressed digital information. receiving a bit compressed digital information subjected to error correction Te, the transmission parity signal
A different parity signal adding means for adding recording parity signal, recording means for recording the compressed digital information the record parity signal <br/> is added by the parity signal adding means to the recording medium and issue the recording The recording time by means depends on the time axis conversion
Playback when the length is set and the time axis conversion is released
A digital information recording apparatus comprising: a control unit that controls the recording unit so as to be different from the length of time . 3. A reproducing apparatus for a recording medium on which digital information is recorded, wherein the recording medium is error-corrected based on a transmission parity signal added to the digital information which is time-axis converted and bit-compressed. Recording different from the transmission parity signal
Compressed digital information to which a parity signal is added is recorded, and reproducing means for reproducing the compressed digital information from the recording medium, and reproducing by canceling the time axis conversion by the reproducing means.
The length of the reproduction time varies depending on the time axis conversion.
And the length of the recording time for recording the compressed digital information in
Control means for controlling the reproducing means differently, error correcting means for error correcting the compressed digital information reproduced by the reproducing means based on the recording parity signal , and compressed digital information error-corrected by the error correcting means. And a bit expanding means for expanding the bit corresponding to the bit compression. Wherein receiving the bit compressed digital information subjected to error correction based on the time axis converted and transmitted parity signal added to the digital information bits compressed, the heat transfer
A recording parity signal different from the transmission parity signal is added and recorded on a recording medium, the bit-compressed digital information is reproduced from the recording medium, error correction is performed based on the recording parity signal , and bits corresponding to the bit compression are recorded. A digital information recording / reproducing method for expanding, wherein a recording time on the recording medium is a length corresponding to the time axis conversion.
And the playback time is the length obtained by canceling the time axis conversion.
A digital information recording / reproducing method characterized by controlling as described above . 5. A digital information recording method for recording digital information on a recording medium, wherein bit-compressed digital information is error-corrected based on a transmission parity signal which has been time-axis converted and added to bit-compressed digital information. Receiving the transmission parity signal
Recorded on a recording medium by adding different recording parity signal and No., long recording time on the recording medium corresponding to the time axis conversion
From the recording medium, the compressed digital information is
When the time axis conversion is canceled and the playback time is different,
A method for recording digital information, characterized in that it is controlled so that 6. A digital information reproducing method for reproducing digital information from a recording medium, wherein the recording medium is error-corrected based on a transmission parity signal added to the time-axis converted and bit-compressed digital information. , Recording different from the transmission parity signal
Compressed digital information added with a parity signal is recorded, and the time axis conversion from the recording medium is canceled and reproduced.
The length of the reproduction time depends on the time axis conversion
Digital data characterized in that the digital information is controlled and reproduced so as to be different from the recording time length for recording, error correction is performed based on the recording parity signal, and bit expansion is performed corresponding to the bit compression. Information reproduction method.