JPH0817470B2 - Recording and playback device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording / reproducing apparatus adapted to record / reproduce still image information in the form of digital signals using a magnetic tape.

2. Description of the Related Art As one of conventional recording / reproducing apparatuses, a digital signal is used that converts an audio signal into a digital signal and records it on a magnetic tape, and also converts a digital signal recorded on the magnetic tape into an audio signal for reproduction. An audio tape recorder (hereinafter referred to as DAT) is well known. In the case of this DAT, when audio signals are converted to digital signals and recorded on a magnetic tape, information for error correction can also be recorded at the same time, so even if some of the recorded information is lost, it can be restored. Therefore, not only the original sound can be reproduced faithfully, but also the sound with less noise can be reproduced.

By the way, in the above-mentioned conventional DAT, a two-channel mode in which two channels for individually recording two types of audio signals are set in a magnetic tape as an operation mode, and four types of audio signals are individually controlled. There is one that allows selection of a four-channel mode in which four channels for recording are set on a magnetic tape. Among them, in the 2-channel mode, two kinds of audio signals corresponding to the two speakers arranged on the front left side and the front right side with respect to the listener are recorded on the magnetic tape, and in the 4-channel mode, the front side with respect to the listener. Left side, front right side, rear left side,
Four types of audio signals corresponding to the four speakers arranged on the rear right side are recorded.

In the case of the 4-channel mode, an audio signal is recorded on two of the channels and a still image video signal is recorded on the remaining two channels, and the audio signal and the video signal are simultaneously reproduced from one magnetic tape. Such a system is also known from the past. In this case, 1
The still image video signal for the screen is recorded on the magnetic tape by assigning a plurality of tracks as one unit, and in the reproducing operation, the reproduction is started from the stop position of the magnetic tape.

However, in the case of the above-mentioned conventional DAT, at the time of the reproducing operation, for example, in the middle of a recording area where a still image video signal for one screen is recorded on the magnetic tape or at the time of recording the still image signal. Playback may start from a non-displayed area. At this time, a still image with a part of the screen is displayed at the start of playback, or until the next one screen of the still image video signal is finished playing. In the meantime, a situation occurs in which only the sound is played and the still image is not displayed, and it takes a long time to display the complete still image.

Therefore, an object of the present invention is a recording / reproducing apparatus for recording / reproducing still image information as a digital signal using a magnetic tape, and shortening the time required until a complete still image is displayed during the reproduction. It is an object of the present invention to provide a recording / reproducing device that can be used.

Means for Solving the Problems The present invention provides a video signal of a still image as a digital signal,
One screen is recorded as one unit over a number of continuous tracks on the magnetic tape, and a recording area for recording a video signal and a non-recording area where no video signal is recorded are magnetically recorded on the still surface for one screen. In a recording / reproducing apparatus provided alternately on the tape, a sub-signal recording portion of each track of the recording area and the non-recording area has a first identification signal for determining whether or not it is a recording area and a head of the recording area. Recording means for recording a second identification signal for discriminating whether or not the area, and first and second recording means for recording the magnetic tape when the magnetic tape is running.
Discriminating means for discriminating the position of the recording / reproducing head by the combination of the first and second discriminating signals, and fast-forwarding the magnetic tape based on the discrimination result by the discriminating means in response to the reproduction command. The recording / reproducing apparatus is characterized by including reproducing means for performing rewinding and reproducing the recording area when the head of the recording area of the magnetic tape is detected by the determining means.

Operation According to the present invention, the recording area of the video signal of the still image for one screen and the non-recording area are alternately provided on the magnetic tape, and the recording means records the recording area and the non-recording area on each track. In the sub-signal recording section, a first identification signal for determining whether it is a recording area and a second identification signal for determining whether it is a head area in the recording area are recorded, and in reproducing, The position of the recording / reproducing head is discriminated based on the first and second identification signals, and the magnetic tape is fast forwarded or rewound based on the discrimination result to detect the beginning of the magnetic tape and reproduce the magnetic tape. Playback can be performed from the beginning of a still image for one screen. Therefore, a complete still image can be displayed within a short time after the start of the reproducing operation.

Moreover, according to the present invention, even if the non-recording area is small, when the first partial area B of the recording area is detected, when the partial partial area B is detected, the recording is performed as described above. Since the area is reproduced, it is possible to surely reproduce from the head of the recording area.

Embodiment 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 / reproducing apparatus is a DAT capable of selecting the above-mentioned four-channel mode as an operation state, and two channels out of the four channels are for recording and reproducing two kinds of audio signals and the remaining two channels. Are assigned for recording and reproducing still image signals.

In FIG. 1, an input terminal TR is a terminal for inputting one kind of audio signal, and the audio signal in this case is, for example, an audio signal to be output from a speaker arranged on the front right side of the listener. Is. The other input terminal TL 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 arranged on the front left side with respect to the listener. is there. Still another input terminal TV is a terminal for inputting a video signal of a still image. These input terminals TR, TL, TV are connected to corresponding analog-digital (hereinafter referred to as A / D) conversion circuits 1, 2, 6, respectively.

The A / D conversion circuits 1 and 2 have corresponding input terminals TR and TL, respectively.
It has a function of converting the audio signal input from the device into, for example, 12-bit digital audio signals D1 and D2. A / D conversion circuit 1, 2
The respective output terminals of are connected to the input terminals 51 and 52 of the changeover switch 5 through the lines 3 and 4, respectively.

The A / D conversion circuit 6 converts the video signal input from the corresponding input terminal TV into, for example, an 8-bit digital video signal D3.
With the function to convert to. The output terminal of the A / D conversion circuit 6 is connected to the data bus 7.

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

A parallel-serial (hereinafter referred to as P / S) conversion circuit 9 is separately connected to the data bus 7. This P / S
The 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 this into a serial signal from a parallel signal, and outputting it. The output terminal of the P / S conversion circuit 9 is connected to the input terminal 53 of the changeover switch 5.

The change-over switch 5 has a function of selectively applying a digital signal derived to each of the input terminals 51 to 53 to the output terminal 54, and the output terminal 54 is connected to the recording signal processing section 11 of the next stage. .

The recording signal processing unit 11 has a modulation function of modulating an input digital signal, a sub information adding function of adding error correction and other sub information to the input digital signal, and the like. The signal processed at 11 is recorded on the magnetic tape 12. In the case where the above-mentioned voice signal is music, for example, a start ID indicating the beginning of a song or a magnetic tape 12 is used as a sub-signal added by the sub-information adding function.
The sub-information called the control ID such as the end ID that indicates the end of the recording area, the total time that is the required playback time from the beginning of the magnetic tape 12 to each midway, and the song that is the required playback time for each song. Sub information called pack data indicating time etc. is generated.

In the case of this embodiment, in the recording signal processing unit 11,
Back data in the format shown in Table 1 below is generated as one of the sub information added to the digital signal.

Upper 4 bits B7 to B of the first byte PC1 of them
A pack item, which is a code for identifying the content of the pack data, is written in 4. For example, if this pack item (pack item) is "0001", the content of the pack data is the song time. "0010" indicates that the content of the pack data is the total time, and "1110" indicates that the content of the pack data is a still image page.

An identification code ID1 indicating whether or not the recording area of the pack data in the recording area of the magnetic tape 12 is an area in which still image information (digital video signal) is recorded is written in the bit B3 of the byte PC1. For example, when the identification code ID1 is 1, it indicates a still image information recording area, and when the identification code ID1 is 0, it indicates a still image information unrecorded area. Same byte pc
An identification code ID2 indicating whether or not the pack data recording area in the recording area of the magnetic tape 12 is the head of the still image information recording area for one screen is written in the bit B2 of the 1 portion. ID2 = 1 is written in the first 10 tracks of the information recording area.

The upper and lower 4 bits of each of the pack data bytes PC2 and PC3 shown in Table 1 are B7 to B4 and B3 to B0.
CD 4-digit page identification code PAGE1 to PAGE4 is written. Furthermore, as shown in Table 1, pack parity, which is data for error correction of the pack data, is written in the last byte PC8 of each pack data.

In FIG. 1, the reproduction signal processing unit 13 includes a magnetic tape 12
It has a demodulation function for the signal read from the device and a processing function for performing processing such as error correction from the read sub-signal, and its output terminal is connected to the input terminal 154 of the changeover switch 15 via the line 14. ing. The processing function of the reproduction signal processing unit 13 is such that when the pack data to be reproduced at the start of reproduction is not at the head of the still image information recording area, the magnetic tape 12 is set to the head of the still image information recording area. The function to output the command to rewind to the position is included.

The change-over switch 15 has output terminals 151, 152, 153, and an input terminal 15 via the line 14 from the reproduction signal processing section 13.
It has a function of selectively applying the digital signal derived to 4 to each of the output terminals 151 to 153. Among them, output terminals 151,15
2 are connected to corresponding digital-analog (hereinafter referred to as D / A) conversion circuits 16 and 17, respectively.

The D / A conversion circuits 16 and 17 are output terminals 151 and 15 of the selector switch 15.
It has the function of converting the digital signal derived in 2 into an analog signal. The output terminals of the D / A conversion circuits 16 and 17 are connected to the corresponding output terminals TR1 and TL1, respectively.

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

An image memory 8b different from the image memory 8a described above is connected to the data bus 7. These two image memories 8a and 8b serve to store digital signals output from the S / P conversion circuit 18 during reproduction.

Further, another D / A conversion circuit 19 is connected to the data bus 7. The D / A conversion circuit 19 has a function of converting a digital signal read from the image memories 8a and 8b during reproduction into an analog signal. The output terminal of the D / A conversion circuit 19 is connected to the output terminal TV1.

FIG. 2 is a plan view schematically showing a part of the magnetic tape 12 on which the digital video signal is recorded by the DAT, and FIG. 3 is a recording area of the magnetic tape 12 and Table 1. It is explanatory drawing which shows the correspondence with the value of identification code ID1, ID2 of back data. Referring to FIGS. 2 and 3,
Each operation of recording and reproducing the DAT will be described below.

A sound signal corresponding to the front right speaker is input to the recording input terminal TR, and a sound signal corresponding to the front left speaker is input to the input terminal L. Furthermore, a video signal of a still image is input to the input terminal TV.
The audio signals input from the input terminals TR and TL are A / D
For example, 12-bit digital audio signals D1 and D2 are converted by the conversion circuits 1 and 2 and are output as serial signals on the lines 3 and 4. Digital audio signals D1 and D2 derived on lines 3 and 4
Are applied to the input terminals 51 and 52 of the changeover switch 5, respectively.

The video signal input from the input terminal TV is A / D conversion circuit 6
In, for example, it is converted into an 8-bit digital video signal D3 and given to the data bus 7 as a parallel signal. This digital video signal D3 is sent from the data bus 7 to the image memory.
Given to 8a. In the A / D conversion circuit 6, the input video signal is sampled at a sampling frequency of 14.3 MHz and converted into a digital signal. The digital video signal D3 corresponding to the video signal for one still image thus obtained is stored in the image memory 8a in 1/60 sec. When the writing of the digital video signal D3 corresponding to the video signal for one screen to the image memory 8a is completed, the stored digital video signal is given to the P / S conversion circuit 9 from the data bus 7, and this P / S conversion circuit is supplied. It is derived as a serial signal from 9 to the input terminal 53 of the changeover switch 5.

The output terminal 54 of the change-over switch 5 is selectively supplied with a digital signal derived from the input terminals 51 to 53, and such a digital signal is supplied from the line 10 to the recording signal processing unit 11. In the recording signal processing unit 11, data and other sub-signals for error correction for the input digital processing are
It is added to each digital signal, subjected to signal processing such as modulation, and then recorded on the magnetic tape 12.

At the time of recording, a video signal for one screen of a still image is recorded on the magnetic tape 12 shown in FIG. 2 as a unit of a plurality of tracks shown by hatching on the upper right, and still image signals for a plurality of screens are sequentially recorded. .

In FIG. 2, an arrow T indicates the direction of recording on the magnetic tape 12, and the N-1 and N areas indicate that the video signals of the N-1th and Nth still images are recorded, respectively. Show. An area A interposed between the areas N-1 and N indicates an area in which a video signal of a still image is not recorded. In addition, the recording area D of the above-described sub-signal (the broken line area shown in FIG. 2) is set in each track.

Therefore, in the pack data recorded in the recording area D in the areas N-1, N, the page numbers are N-1, respectively.
It is N. The recording area D in the areas N-1 and N
The identification code ID1 = 1 in the pack data recorded in No. 1 and ID1 = 0 in the pack data in the area A.
Has become. Further, in the area B from the beginning to the 10th track in the area N, that is, in the area shown by vertical hatching in the upper right hatching in FIG. 2, the identification code ID2 of the pack data is 1 and the other tracks. Then, the identification code ID2 of the pack data is 0.

During reproduction and reproduction, the signal read from the magnetic tape 12 is input to the reproduction signal processing unit 13. The reproduction signal processing unit 13 performs demodulation and error correction processing based on the reproduction sub-signal, and the digital signal subjected to such signal processing is given from the line 14 to the input terminal 154 of the changeover switch 15. The changeover switch 15 has output terminals 151, 152, 153, and digital signals corresponding to the audio signals input from the input terminals TR, TL are derived from the output terminals 151, 152, and the derived digital signals are respectively D / A converted. After being converted into an analog signal by the circuits 16 and 17, it is led to the output terminals TR1 and TL1.

A digital signal corresponding to the video signal input from the input terminal TV is derived from the output terminal 153 of the changeover switch 15,
The derived digital signal is given to the S / P conversion circuit 18 and given to the data bus 7 as a parallel signal of 8 bits, for example. This digital signal is given to either one of the image memories 8a and 8b connected to the data bus 7.

A digital video signal is supplied to the D / A conversion circuit 19 via the data bus 7 from the image memory of one of the image memories 8a and 8b in which the storage of the digital video signal has been completed. This digital video signal is a D / A conversion circuit 19
Is converted into an analog signal and led to the output terminal TV1.

Writing of the digital video signal to the image memories 8a and 8b is performed to one of the image memories, and at this time, the digital video signal stored in the other image memory is given to the D / A conversion circuit 19. ing. When the writing operation of the digital video signal to the one image memory is completed, that is, the writing of the digital video signal for one screen is completed, the D / A conversion circuit 19 is provided with the output of the one image memory. Become. At this time, writing of the digital video signal from the S / P conversion circuit 18 is started in the other image memory. In this way, the outputs of the image memories 8a and 8b are alternately given to the D / A conversion circuit 19,
In this way, the display of a still image that changes at certain intervals can be performed by a display device such as a CRT (cathode ray tube).

The sampling frequency in the A / D conversion circuits 1 and 2 is, for example, 32 KHz. The audio signals input from the input terminals TR and TL correspond to, for example, the front right and left speakers of the listener. Two channels are assigned to the video signal input from the input terminal TV. Correspondingly, in the changeover switch 5, the output terminal 54 and the input terminals 51, 52, 53 are sequentially connected.

The changeover operation of the changeover switch 5 is performed corresponding to, for example, the sampling signal having the above-mentioned frequency, and the input terminal 51 is selected during the period of 1/4 of the period of one period of the sampling signal, and is followed by this. The input terminal 52 is selected during the period of 1/4 cycle, and the input terminal 53 is selected during the period of the following half cycle to establish electrical connection with the output terminal 54. In this way, the 12 × 4 bit digital signal is input to the recording signal processing unit 11 during the period of one cycle of the sampling signal.

Since the image memory 8a must store a digital video signal corresponding to one screen of still video, for example, one field period, that is, 1/60 sec A / D period.
It must be possible to store the output of the conversion circuit 3. Therefore, the storage capacity of the image memory 8a is 14.3 (MHz) × 8 (bits) × 1/60 (sec) = 1.911 (M bits) (1).

The digital video signal read from the image memory 8a to the recording signal processing unit 11 is 32 (KHz) × 12 (bits) × 2 = 768 (k bits / sec) (2) per second. Therefore, in order for the digital video signal for one screen to be read out to the recording signal processor 11, 1.911 (M bits) / 768 (k bits / sec) = 2.49 (sec) ... (3) is required. . Since 1/60 sec is required to write the digital video signal for one screen to the image memory 8a, the digital video signal representing one still screen is recorded on the magnetic tape 12 in about 2.5 sec. Will be recorded. Therefore, by reproducing the magnetic tape 12 on which the digital video signal and the digital audio signal are recorded as described above, the sound signal is sonicated and about 2.
It is also possible to display a still image that changes every 5 seconds.

By the way, in the reproducing operation, the position of the magnetic tape 12 at the start of reproduction (the position where the reproducing head corresponds to the magnetic tape 12) is, for example, a video signal recording area of the number N of pages as indicated by a in FIG. If the position is in the middle of S3 + S4, the identification code ID1 = 1 in the pack data of the sub-signal reproduced at this time.

Therefore, the reproduction signal processing unit 13 outputs a command to rewind the magnetic tape 12 based on the detection result of ID1 = 1,
As a result, the magnetic tape 12 is rewound at a high speed as shown by the symbol b in FIG. Since the identification code ID1 = 1 in the video signal recording area S3 + S4 and the identification code ID1 = 0 in the unrecorded area S2, from the change of the identification code ID1 to the beginning of the video signal recording area S3 + S4 of the number of pages N. It is confirmed by the reproduction signal processing unit 13 that the film has been rewound, and by this, an instruction to stop the rewinding is issued, and then the reproduction operation is started.

As described above, since the time required to reproduce the video signal for one screen is 2.5 sec, the time required to rewind the magnetic tape 12 from the video signal recording area S4 to the beginning thereof is the rewind time. If the speed is 10 times the speed at the time of playback, at most 0.25
It will only take sec. In this way, since the video signal is reproduced from the beginning of the video signal recording area S3 + S4, it is possible to display a complete still image for one screen approximately 2.8 seconds after the reproduction is started.

In the above operation, when the unrecorded area S2 is narrow, the video signal recording area S3 + S4
Since it immediately reaches the immediately preceding video signal recording area S1, the section in which the identification code ID1 changes from 1 to 0 is short, and the change may be overlooked. However, at this time, the identification code ID2 = 1 in the area S3 from the beginning of the video signal recording area S3 + S4 to the 10th track, and the identification in the latter half portion (tracks after 10 tracks) of the video signal recording area S1 immediately before is identified. Since the code ID2 = 0, even in such a case, the head of the video signal recording area S3 + S4 can be reliably detected by the change of the identification code ID2 from 1 to 0.

At the start of reproduction, the position of the magnetic tape 12 is indicated by the symbol g in FIG.
Even in the non-recorded area S5 indicated by, the magnetic tape 12 is rewound in the direction indicated by the symbol h in the figure, the head of the video signal recording area S3 + S4 is similarly detected, and reproduction is performed from that position. .

In the above embodiment, the position of the magnetic tape 12 at the start of reproduction is, for example, the video signal recording area indicated by the symbol a in FIG.
The case where the magnetic tape 12 is rewound in the direction indicated by the symbol b in the middle of S3 + S4 has been described, but the present invention is not limited to this, and the magnetic tape 12 is fast-forwarded in the direction indicated by the symbol e and the video signal recording area S6 + S7 of the next page number N + 1 The head may be detected and the reproduction may be started from there. This also applies to the case where the position of the magnetic tape 12 is at the position indicated by the reference character g in the unrecorded area S5 at the start of reproduction.

According to the present invention, when the reproduction start position on the magnetic tape is either the recording area or the non-recording area, the magnetic tape is rewound or fast forwarded at a high speed, and the leading area is detected, Since the recording area is reproduced, it is possible to completely reproduce the recording area for one screen from the beginning.

In particular, according to the present invention, when the non-recorded area is small, it may be possible to fail to detect the non-recorded area during high-speed rewinding or fast-forwarding. When the start area is detected, the recording area is played back. Therefore, even if such a non-recording area is small, it is possible to completely play back and display a still image for one screen. It will be possible.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a recording / reproducing apparatus according to an embodiment of the present invention, and FIG. 2 is a schematic view of a part of a magnetic tape on which a digital video signal is recorded by the recording / reproducing apparatus. FIG. 3 is a plan view schematically showing the correspondence between the recording area of the magnetic tape and the identification codes ID1 and ID2 of the pack data. 1,2,6 …… A / D conversion circuit, 5,15 …… Selection switch, 8a, 8b
...... Image memory, 9 ...... P / S conversion circuit, 11 ...... Recording signal processing unit, 12 ...... Magnetic tape, 13 ...... Reproduction signal processing unit, 1
6,17,19 …… D / A conversion circuit, 18 …… S / P conversion circuit, TR, TL, T
V …… input terminal, TR1, TL1, TV1 …… output terminal

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication location H04N 5/7826 (56) References JP 62-265873 (JP, A) JP 60- 175230 (JP, A) JP 58-164383 (JP, A) JP 60-259071 (JP, A) Actually opened 61-136341 (JP, U) Actually opened 63-181155 (JP, U) 62-138327 (JP, U)

Claims (1)

[Claims] 1. A video signal of a still image as a digital signal,
One screen is recorded as one unit over a number of continuous tracks on the magnetic tape, and a recording area for recording a video signal and a non-recording area where no video signal is recorded are magnetically recorded on the still surface for one screen. In a recording / reproducing apparatus provided alternately on the tape, a sub-signal recording portion of each track of the recording area and the non-recording area has a first identification signal for determining whether or not it is a recording area and a head of the recording area. Recording means for recording a second identification signal for determining whether or not it is an area; and first and second identification signals read from the magnetic tape when the magnetic tape is running, and the first and second identification signals. Discriminating means for discriminating the position of the recording / reproducing head by a combination of the above, and the magnetic tape is fast forwarded or rewound based on the discrimination result by the discriminating means in response to the reproducing command. Recording and reproducing apparatus which comprises a reproducing means for reproducing the recording region due to detecting the beginning of the recording area of the magnetic tape by.