JPH04324169A - Recording and reproducing device - Google Patents

Abstract

PURPOSE:To enable to vary the image data quantity sampling for one picture at the recording time in accordance with the image quality seeked for the image to be recorded in a recording and reproducing device. CONSTITUTION:A sampling frequency is selectively switched with a sampling frequency switching switch 20 at the recording time and the data quantity of the digital video signal for one picture converted with an analog digital conversion circuit 6 is varied. The information of the sampling frequency at this time is recorded on a subinformation recording area of a magnetic tape 12 with a record signal processing part 11 and at the reproducing time, the clock frequency of a digital-analog conversion circuit 19 converting the digital video signal read-out from the magnetic tape 12 to an analog video signal with a clock frequency switching circuit 21 in accordance with the sampling frequency information read-out from the subinformation recording area of the magnetic tape 12, is switched.

Description

[Detailed description of the invention]

0001

[Industrial Field of Application] The present invention is a digital audio tape recorder capable of recording multiple series of signals in a composite manner and reproducing the recorded signals for each series.
Audio Tape recorder; hereinafter referred to as DA
(abbreviated as T) and other recording/reproducing devices.

0002

2. Description of the Related Art A conventional recording/reproducing device converts an audio signal into a digital signal and records it on a magnetic tape, and also converts the digital signal recorded on the magnetic tape into an audio signal and plays it back. DAT is well known.

In the case of this DAT, when converting an audio signal into a digital signal and recording it on a magnetic tape, information for error correction such as parity can be simultaneously recorded as sub information, so that one part of the recorded information can be recorded simultaneously. Even if a portion is missing, it can be repaired, making it possible not only to faithfully reproduce the original sound, but also to reproduce audio with extremely low noise.

By the way, some of the above-mentioned conventional DATs operate in a 2-channel mode in which two channels are set on a magnetic tape in which two types of audio signals are individually recorded, and in a two-channel mode in which two types of audio signals are recorded individually. There is also a 4-channel mode in which four channels are individually recorded on a magnetic tape.

[0005] In the 2-channel mode, two types of audio signals corresponding to the two speakers placed on the front left and front right sides of the listener are recorded on magnetic tape, and in the 4-channel mode, the listener On the other hand, four types of audio signals corresponding to four speakers arranged on the front left side, front right side, rear left side, and rear right side are recorded.

Furthermore, in the case of the above-mentioned 4-channel mode, audio signals are recorded on two of the channels, and still image video signals are recorded on the remaining two channels, so that audio signals and video signals can be recorded from one magnetic tape. Systems that allow simultaneous playback have also been known.

In this method, for example, two image memories each storing one screen worth of still image video signals are prepared, and at the time of recording, one screen worth of video signals is digitally stored before being recorded on a magnetic tape. It is converted into a digital signal by an analog (hereinafter referred to as D/A) conversion circuit, and is then sequentially written to one of the two image memories over a certain period of time (hereinafter referred to as the first time). Then, over a certain period of time (hereinafter referred to as the second period) which is longer than the first period of time, one screen worth of digital video signals is read out from the image memory and recorded on the magnetic tape.

[0008] At this time, the audio signal input in parallel with the video signal is also converted into a digital signal by the D/A conversion circuit. Therefore, a video signal for one screen and an audio signal, such as a narration, corresponding to this screen are recorded as a pair on the magnetic tape.

On the other hand, during playback, the digital video signal for one screen read from the magnetic tape is once sequentially written into one of the above-mentioned image memories over a second period of time, and after the writing is completed, the digital video signal is read from the magnetic tape. 1 over the first time from the image memory
A video signal corresponding to a screen is read out, and the read out video signal is converted into an original analog video signal by a digital-to-analog (hereinafter referred to as D/A) conversion circuit and reproduced.

At this time, the digital audio signal read from the magnetic tape in parallel with the digital video signal is also converted into an analog audio signal by the D/A conversion circuit and reproduced. As a result, when a still image video signal for one screen is reproduced, an audio signal such as a narration corresponding to the still image is reproduced in parallel.

[0011]

[Problems to be Solved by the Invention] However, in the above-mentioned conventional DAT, the A/D conversion circuit performs A/D conversion of the video signal at a constant sampling frequency, and therefore the image memory is 1 once written
The amount of still image data for a screen is constant. Therefore, 1
The time required to record or read the screen from a magnetic tape is fixed at a fixed time like the second time mentioned above, and furthermore, the number of still images that can be recorded on a magnetic tape is also fixed at a fixed number. will be restricted.

That is, the conventional DAT has a problem in that it cannot meet the demand for recording as many still images as possible on a magnetic tape, even if the image quality is poor.

[0013] Accordingly, an object of the present invention is to provide a recording and reproducing apparatus that can variably set the amount of image data for one screen to be sampled during recording, depending on the image quality required of the image to be recorded.

[0014]

[Means for Solving the Problems] The present invention converts a video signal and an audio signal into digital signals using an analog-to-digital conversion means, records the converted signals in the main information recording area of a magnetic tape, and reads the digital signals from the magnetic tape. In a recording and reproducing apparatus that converts a video signal into an analog signal using a digital-to-analog converting means and reproduces the original video signal and audio signal, a sampling frequency is selected when the analog-to-digital converting means converts the video signal into a digital signal. sampling frequency switching means for automatically switching the sampling frequency; sampling information recording means for recording information on the sampling frequency selected by the sampling frequency switching means in a sub-information recording area of the magnetic tape during recording; Based on the sampling frequency information read from the information recording area, the clock frequency at which the digital-to-analog conversion means converts the digital signal into the original video signal is switched and set to correspond to the sampling frequency at the time of recording. The present invention is a recording/reproducing apparatus characterized by comprising a clock switching means.

[0015]

[Operation] According to the present invention, by selectively switching the sampling frequency using the sampling frequency switching means during recording, the amount of data of one screen worth of digital video signal converted by the analog-to-digital conversion means can be changed, and sampling The lower the frequency, the smaller the amount of data, the shorter the time required for recording, and the greater the number of screens that can be recorded on the magnetic tape. Information on the sampling frequency at this time is recorded in the sub-information recording area of the magnetic tape by the sampling information recording means.

During playback, the clock switching means converts the digital video signal read from the magnetic tape into an analog video signal according to the sampling frequency information read from the sub-information recording area of the magnetic tape. Switch the clock frequency of the means. As a result, the digital video signal is converted to an analog video signal at a clock frequency that corresponds to the sampling frequency at which analog-to-digital conversion is performed during recording, and the signal is reproduced.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing a schematic configuration of a recording/reproducing apparatus which is an embodiment of the present invention. This recording and reproducing device is a DAT that allows the above-mentioned four-channel mode to be selected as an operating state, and two of the four channels are used for recording and reproducing two types of audio signals, and the remaining two channels are used for recording and reproducing two types of audio signals. is allocated for recording and reproducing still image video signals.

The input terminal TR is a terminal for inputting one type of audio signal, and the audio signal in this case is, for example, an audio signal to be output from a speaker placed in front of the listener on the right side. be. Another input terminal TL is
This is a terminal for inputting another type of audio signal, and the audio signal in this case is, for example, an audio signal to be output from a speaker placed on the front left side with respect to the listener.

Still another input terminal TV is a terminal for inputting a still image video signal. These input terminals TR
, TL, and TV are the corresponding A/D conversion circuits 1,
2 and 6.

[0020] The A/D conversion circuits 1 and 2 have a function of converting the audio signals inputted from the corresponding input terminals TR and TL into, for example, 12-bit digital audio signals D1 and D2 and outputting them as serial signals. have In this embodiment, the sampling frequency of the A/D conversion circuits 1 and 2 is, for example, 32 KHz.

The output terminals of the A/D conversion circuits 1 and 2 are connected to the input terminals 51 and 5 of the changeover switch 5 via lines 3 and 4.
2 are connected to each other.

The A/D conversion circuit 6 has a corresponding input terminal T.
It has a function of converting the video signal input from V into, for example, an 8-bit digital video signal D3 and outputting it to the data bus 7 as a parallel signal. This A/D conversion circuit 6 includes
A sampling frequency changeover switch 20 is connected. The video signal input to the A/D conversion circuit 6 is sampled at a sampling frequency designated by a sampling frequency changeover switch 20 and converted into a digital signal.

In this embodiment, the sampling frequency changeover switch 20 has a normal sampling mode that specifies a sampling frequency of 14.3MHz, and a sampling frequency of 10.7MHz.
It is provided with a function of selectively switching to either a low sample mode that specifies a sampling frequency of MHz, and a function of providing information on the switched mode to a recording signal processing section 11, which will be described later.

An image memory 8a is connected to the data bus 7. This image memory 8a is a memory for taking in one screen worth of digital video signal D3 outputted from the A/D conversion circuit 6 via the data bus 7 and storing it.

A parallel-to-serial (hereinafter referred to as P/S) conversion circuit 9 is separately connected to the data bus 7. This P/S conversion circuit 9 has a function of taking in an 8-bit digital video signal read from the image memory 8a via the data bus 7, converting it from a parallel signal to a serial signal, and outputting the signal. The output terminal of this P/S conversion circuit 9 is connected to the input terminal 53 of the changeover switch 5.

The changeover switch 5 has input terminals 51 to 51.
It has a function of selectively providing the digital signal derived from the output terminal 53 to an output terminal 54, and the output terminal 54 is connected to the recording signal processing section 11 at the next stage.

The recording signal processing section 11 has a modulation function for modulating the input digital signal, a sub information addition function for adding error correction information and other sub information to the input digital signal, etc. This recording signal processing section 11
The processed signals are recorded on the magnetic tape 12.

The reproduced signal processing unit 13 has a demodulation function for demodulating the signal read from the magnetic tape 12 and a processing function for performing processing such as error correction from the read sub-information.
Its output terminal is connected via line 14 to an input terminal 154 of changeover switch 15.

The changeover switch 15 has an output terminal 151
, 152, 153, and has a function of selectively supplying a digital signal derived from the reproduced signal processing section 13 to the input terminal 154 via the line 14 to each output terminal 151-153. Output terminals 151 and 152 are connected to corresponding D/A conversion circuits 16 and 17, respectively.

The D/A conversion circuits 16 and 17 have a function of converting the digital signals output to the output terminals 151 and 152 of the changeover switch 15 into analog signals. Each output terminal of the D/A conversion circuits 16 and 17 is connected to a corresponding output terminal TR1 and TR2, respectively.

Another output terminal 1 of the changeover switch 15
53 is connected to a serial-parallel (hereinafter referred to as S/P) conversion circuit 18. This S/P conversion circuit 18
has a function of converting the digital signal derived to the output terminal 153 of the changeover switch 15 into, for example, an 8-bit parallel signal and outputting the signal. The output terminal of this S/P conversion circuit 18 is connected to the data bus 7.

Connected to the data bus 7 is an image memory 8b that is different from the image memory 8a mentioned above. These two image memories 8a and 8b have the function of storing digital signals output from the S/P conversion circuit 18 during playback.

The data bus 7 also has another D/A.
A conversion circuit 19 is connected. This D/A conversion circuit 1
Reference numeral 9 has a function of converting digital signals read from the image memories 8a and 8b during playback into analog signals. The output terminal of this D/A conversion circuit 19 is connected to the output terminal TV1.

The clock frequency switching circuit 21 determines whether the sampling frequency information read from the subcode recording area of the magnetic tape 12 and processed by the reproduction signal processing unit 13, that is, whether the sampling frequency at the time of recording is in the normal sample mode or the low sample mode. It has a function of switching and specifying the clock frequency in the D/A conversion circuit 19 based on sub-information identifying the mode.

That is, the sampling frequency information is 14
．． When indexing the sampling frequency of 3MHz,
If a clock frequency corresponding to the sampling frequency is specified as the clock frequency of the D/A conversion circuit 19, and the sampling frequency information indicates a sampling frequency of 10.7 MHz, the clock frequency corresponding to the sampling frequency is D. /A conversion circuit 19 clock frequency.

FIG. 2 is a flowchart showing the recording operation by the DAT, and FIG. 3 is a flowchart showing the reproduction operation by the DAT. Each operation of recording and reproducing the above-mentioned DAT will be explained below with reference to FIGS. 2 and 3.

Recording In the flowchart of FIG. 2, following the start of the recording operation in step s1, in step s2 the input terminal TR is
An audio signal corresponding to the front right speaker is input to the listener, and an audio signal corresponding to the front left speaker is input to the input terminal TL. Furthermore, a still image video signal is input to the input terminal TV.

The audio signals input from the input terminals TR and TL are processed at a sampling frequency of 32K in step s3.
The signals are converted into, for example, 12-bit digital audio signals D1 and D2 by A/D conversion circuits 1 and 2 that perform sampling operations at Hz, respectively, and are output as serial signals to lines 3 and 4. The digital audio signals D1 and D2 led out to the lines 3 and 4 are input to the input terminals 51 and 52 of the changeover switch 5.
are given to each.

Further, in step s4, it is confirmed whether the sampling frequency changeover switch 20 specifies the normal sample mode or the low sample mode, and the sampling frequency of the A/D conversion circuit 6 is changed depending on the mode. can be determined.

That is, when the normal sample mode is designated, the video signal input from the input terminal TV is sampled at a sampling frequency of 14.3 MHz by the A/D conversion circuit 6 in step s5, and converted into an 8-bit digital signal. It is converted into a video signal D3 and given to the data bus 7 as a parallel signal. Furthermore, when the low sample mode is specified, the input video signal is sampled at a sampling frequency of 10.7 MHz by the A/D conversion circuit 6 in step s6, and converted into an 8-bit digital video signal D3. and is applied to the data bus 7 as parallel signals.

This digital video signal D3 is processed in step s.
7, the data is applied from the data bus 7 to the image memory 8a.

The data amount Dvi of the digital video signal D3 for one screen of still images stored in the image memory 8a is, for example, the output of the A/D conversion circuit 6 for a period of one field, that is, a period of 1/60 sec. From, when in normal sample mode,

[0043]

[Equation 1] Dvi = 14.3 (MHz) x 8 (bits)
×1/60 (sec) ≒1.91
(M bit) When in low sample mode,

[0044]

[Formula 2] Dvi = 10.7 (MHz) x 8 (bits)
×1/60 (sec) ≒1.43
(M bits).

When the writing of the digital video signal D3 corresponding to the video signal for one screen into the image memory 8a is completed,
The stored digital video signal is given from the data bus 7 to the P/S conversion circuit 9 in step s8, and further led out as a serial signal from the P/S conversion circuit 9 to the input terminal 53 of the changeover switch 5 in step s9.

In this case, the A/D conversion circuits 1 and 2 convert
The data amount Da of the digital audio signals D1 and D2 obtained by D conversion is as follows per 1 sec.

[0047]

[Equation 3] Da=32 (KHz) x 12 (bits) x 2 (ch) =
768 (K bits/sec). Therefore, the time T required for one field's worth of digital video signals to be taken into the recording signal processing section 11
When v is in normal sample mode,

[0048]

[Formula 4] Tv=1.91 (M bits)/768 (K bits/sec) ≒2.49 (sec) When in low sample mode,

[0049]

[Equation 5] Ta=1.43 (M bits)/768 (K bits/sec) ≈1.86 (sec). That is, compared to the normal sample mode, the time required to record the video signal onto the magnetic tape 12 is significantly reduced in the low sample mode.

Digital signals derived from the input terminals 51 to 53 are selectively applied to the output terminal 54 of the changeover switch 5, and such digital signals are applied to the recording signal processing section 11 from the line 10. That is, the switching operation in the changeover switch 5 is performed in synchronization with the sampling period in the A/D conversion circuits 1 and 2, and each input terminal 51 from which an audio signal is derived is assigned one channel.
, 52, 1/1 of the above sampling period
The output terminals 54 are connected only for four periods.

On the other hand, for the input terminal 53 from which the video signal to which two channels are allocated is derived, the output terminal 5 is connected only during a half period of the sampling period.
4 is connected. By cyclically switching the connection state, each digital signal is selectively provided to the recording signal processing section 11.

In the next step s10, the video signal recording signal processing unit 11 adds error correction data and other sub-information to each digital signal, and performs signal processing such as modulation. be done.

The signal that has undergone signal processing is processed in the next step s.
At step 11, the data is recorded on magnetic tape 12.

At this time, sampling information identifying whether the mode designated by the sampling frequency changeover switch 20 is normal sample mode or low sample mode is also included as one of the sub information in the sub code recording area of the magnetic tape 12 in step s12. recorded in

In the next step s13, it is checked whether the recording operation should be ended or not. If the recording operation is to be continued, the process returns to step s2 and the above operation is repeated.

If it is confirmed in step s13 that the recording operation is to be completed, the process moves to the next step s14, where the recording operation is completed.

Reproduction In the flowchart of FIG. 3, following the start of the reproduction operation in step n1, in step n2, a recording signal is read from the magnetic tape 12 by a rotary head (not shown), and the read signal is sent to the reproduction signal processing section 13. is input.

In the next step n3, the reproduced signal processing unit 13 performs demodulation and error correction processing based on the reproduced sub-information, and the digital signal subjected to such signal processing is sent from the line 14 to the changeover switch 15. Input terminal 154
given to.

At this time, the clock frequency is designated from the clock switching circuit 21 to the D/A conversion circuit 19 in step n4 based on the sampling information which is one of the reproduction sub-information. That is, the magnetic tape 12
When the sampling information read from indicates normal sample mode, the sampling frequency is 14.3M.
A clock frequency corresponding to 10.7 MHz is specified, and when the sampling information indicates low sample mode, a clock frequency corresponding to a sampling frequency of 10.7 MHz is specified.

The changeover switch 15 has output terminals 151,1
52, 153, and the output terminals 151, 152 derive digital signals corresponding to the audio signals input from the input terminals TR, TL, and the derived digital signals are respectively D/A in step n5. conversion circuit 16,
17 into an analog signal and output terminal TR1,
It is derived to TL1.

A digital signal corresponding to the video signal inputted from the input terminal TV is derived from the output terminal 153 of the changeover switch 15, and the derived digital signal is transferred to the output terminal 153 of the changeover switch 15.
6, it is applied to the S/P conversion circuit 18 and applied to the data bus 7 as a parallel signal of 8 bits each. This digital signal is given to either one of the image memories 8a and 8b connected to the data bus 7 in step n7.

In the next step n8, the image memory 8
The data bus 7 is transferred from the image memory to which digital video signals for one screen have been written from either a or 8b.
A digital video signal is given to the D/A conversion circuit 19 via the D/A conversion circuit 19. This digital video signal is converted into an analog signal by the D/A conversion circuit 19 in step n9, and is output to the output terminal TV1.

Writing of digital video signals to the image memories 8a and 8b is performed to either one of the image memories, and at this time, the digital video signal written to either of the other image memories is transferred to the D/A conversion circuit. It is given to 19.

When the writing operation of the digital signal to the one image memory is completed, that is, when the writing of the digital video signal for one screen is completed, the D/A conversion circuit 1
9 is supplied with the output of the one image memory.

At this time, the other image memory contains the S/
Writing of the digital video signal from the P conversion circuit 18 is started. In this way, the outputs of the image memories 8a and 8b are alternately given to the D/A conversion circuit 19, and in this way, the display of still images that change at regular intervals can be displayed using, for example, C
This is performed using a display device such as an RT (cathode ray tube).

The clock frequency of the D/A conversion circuit 19 is:
As described above, since it is specified according to the sampling frequency information which is the sub-information, the clock frequency of D/A conversion is specified according to the data amount of the video signal at the time of recording.

In the next step n10, it is checked whether the reproducing operation should be ended or not. If it is confirmed that the reproducing operation is to be continued, the process returns to step n2 and the above operation is repeated. If it is confirmed in step n10 that the reproducing operation is to be completed, the process moves to the next step n11, where the reproducing operation is completed.

In the above embodiment, the sampling frequency when A/D converting the video signal during recording is set to 14.3.
Although the case where the sampling frequency is switched between two types, MHz and 10.7 MHz, has been described, the sampling frequency is not limited to this, and the sampling frequency may be set and switched steplessly.

[0069]

As described above, according to the recording and reproducing apparatus of the present invention, the sampling frequency is selectively switched by the sampling frequency switching means during recording, and the digital video for one screen is converted by the analog-to-digital converting means. In addition to changing the data amount of the signal, information on the sampling frequency at this time is recorded in the sub-information recording area of the magnetic tape by the sampling information recording means.

During playback, digital-to-analog conversion means converts the digital video signal read from the magnetic tape into an analog video signal using the clock switching means in accordance with the sampling frequency information read from the sub-information recording area of the magnetic tape. It is designed to switch the clock frequency of the

Therefore, the amount of data for one screen to be recorded changes depending on the sampling frequency that is set, and the time required for recording can also be changed accordingly. The required time and the number of images to be recorded on the magnetic tape can be selected.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a schematic configuration of a recording/reproducing apparatus that is an embodiment of the present invention.

FIG. 2 is a flowchart showing a recording operation by the recording/reproducing apparatus of the embodiment.

FIG. 3 is a flowchart showing a reproducing operation by the recording/reproducing apparatus of the embodiment.

[Explanation of symbols]

1, 2, 6 A/D conversion circuits 5, 15 Changeover switches 8a, 8b Image memory 9 P/S conversion circuit 11 Recording signal processing unit 12 Magnetic tape 13 Playback signal processing unit 16, 15, 19 D/A conversion circuit 18 S/P conversion circuit 20 Sampling frequency switching switch 21 Clock frequency switching circuit TR, TL, TV Input terminal TR1, TL1, TV1 Output terminal

Claims (1)

[Claims] Claim 1: A video signal and an audio signal are converted into digital signals by an analog-to-digital converter and recorded in the main information recording area of a magnetic tape, and the digital signals read from the magnetic tape are converted to an analog signal by an analog-to-analog converter. In the recording and reproducing apparatus that converts the video signal into an original video signal and reproduces the original video signal and audio signal, the analog-to-digital conversion means selectively switches the sampling frequency when converting the video signal into the digital signal. , sampling information recording means for recording information on the sampling frequency selected by the sampling frequency switching means in a sub-information recording area of the magnetic tape during recording; and sampling information read from the sub-information recording area of the magnetic tape during reproduction. Clock switching means for switching and setting the clock frequency at which the digital-to-analog converting means converts the digital signal into the original video signal, based on frequency information, so as to correspond to the sampling frequency at the time of recording. A recording/playback device characterized by: