JP2638659B2 - Digital audio tape recorder - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital audio tape recorder capable of recording a still image.

[Prior Art] A digital audio tape recorder (DAT) is a dedicated device for recording and reproducing an audio signal. Recently, a DAT capable of superimposing and recording a video signal on the audio signal and reproducing the video signal has been developed. ing.

In a normal case, a digital audio signal of N bits (N is an integer) is recorded and reproduced as it is. On the other hand, the newly developed DAT uses the upper M bits (M is an integer and M <N) as shown in FIG. 6, for example, when N = 16 bits, the upper 10 bits are digitally An audio signal is allocated, and a digital video signal for a still image is allocated to the remaining (N-M) bits, that is, the lower 6 bits, for recording and reproduction.

The digital video signal is recorded and reproduced, for example, in units of one frame. Therefore, the screen is reproduced (monitor) in units of one frame.

[Problems to be Solved by the Invention] In the case of recording a composite digital signal as described above, especially in the case of a wasch-shot recording mode in which images are recorded one frame at a time, the last data of one frame is recorded. (Data of digital video signal or digital audio signal) is monitored, and when the last data is recorded, the recording / reproducing system (not shown) is controlled to the recording pause mode.

However, even if the recording / reproducing system is set to the recording pause mode immediately after recording the last data of one frame, the magnetic tape slightly runs because the tape traveling system constituting the recording / reproducing system has inertia. And then stop.

Then, the synthesized digital signal for the next one frame is recorded in that state, so that a blank section exists between the recording frames X, Y, Z,... As shown in FIG.

Due to this blank section, the recording density of the magnetic tape is reduced, and the time for reproducing one frame of the synthesized digital signal is slightly increased.

It is conceivable to return the magnetic tape slightly so as to eliminate the blank section. However, in this case, it is necessary to monitor the recorded image data in order to return the magnetic tape by a predetermined length. However, this auditing method is not easy, and there is a disadvantage that the cost will be increased in the future.

In view of the above, the present invention solves such a problem, and proposes a DAT in which the configuration is simplified to prevent a recording magnetic blank section from occurring.

[Means for Solving the Problems] In order to solve the above-mentioned problems, in the present invention, N
A digital audio signal is allocated to upper M bits (M is an integer, N> M) of a digital signal composed of bits (N is an integer), and a digital video signal is allocated to the remaining (N−M) bits. In a digital audio tape recorder in which a composite digital signal is formed and recorded and reproduced in units of one frame, a predetermined identification signal is inserted and recorded at the beginning and end of the composite digital signal forming one screen, and recorded. The recording / reproducing system is controlled to the recording pause mode using the identification signal inserted last.

[Operation] A predetermined identification signal (ID) is inserted and recorded at the beginning and end of the composite digital signal constituting one screen. FIG. 2 shows an example.

Then, the identification signal (end ID (E ·
Using ID)), the recording / reproducing system is controlled to the recording pause mode. Specifically, the recording pause mode is set through the following procedure.

The end ID is based on a parallel 8-bit identification code.
This is composed of, for example, p (1810 in this example) consecutive identification codes, which are recorded continuously. And
As shown in FIG. 4, when the end of the recording of the end ID is detected, the recording / reproducing system is controlled to the reverse mode. At the same time, the number of end IDs is counted.

When the count value reaches pm (for example, 150),
Controlled to playback mode. The end ID is also counted in the playback mode. When the value becomes nm (for example, 100), the mode is controlled to the recording pause mode.

Even if the recording pause mode is controlled, the magnetic tape slightly runs because of the inertia in the tape running system, and then stops completely.

In this stopped state, the magnetic head almost faces the last position of the end ID. As a result, there is no blank section in the recording mode.

Next, an example of a digital audio tape recorder according to the present invention will be described in detail with reference to FIG.

In this example, the digital audio signal and the digital video signal are synthesized by selecting N = 16 and M = 8, but this is only an example.

For the sake of convenience, the description will be made with reference to FIG. 2 and subsequent figures, but FIG. 2 is a format showing a data configuration example of one frame.

In the figure, various control signals (ID signals) are inserted before and after a composite digital signal (shown as data in the figure).

Here, S-ID is the start ID indicating the start of data
, And the MD ID is a mode ID, which is used to distinguish between an odd field and an even field.

The LS ID (last start ID) is an ID for distinguishing from the data, and is the last ID inserted in the preceding stage. E · ID (end ID) is an ID added to the end of data. The end ID is composed of p parallel 8-bit identification codes.

The total ID insertion time is approximately 80 msec, and data is inserted for approximately 2.48 sec. Therefore, one frame is approximately 5 seconds.

According to the present invention, when recording a composite digital signal, the end ID recorded at the end of the composite digital signal is detected, and the recording / reproducing system is controlled based on the detected end ID, so that a recording pause mode in which a blank section does not occur finally is set. What we are trying to achieve.

Therefore, digital audio tape recorders (DA
T) is configured as shown in FIG.

In FIG. 1, reference numeral 10 denotes a specific example of a recording / reproducing circuit (in particular, a video system) in a digital audio tape recorder (DAT) according to the present invention.

In the figure, a terminal 12 is supplied with a video signal to be recorded. This video signal is converted into a digital signal (8 bits) by the A / D converter 14, and the digital signal is converted into the washer switch 16, the first frame switching switch 18, and the first and second switches.
Are sequentially distributed to and stored in the four field memories 30 to 36 via the field changeover switches 20 and 22.

Therefore, the field memories 30 and 32 are for odd frames, and the field memories 34 and 36 are for even frames.

The digital video signal read from these is
3. The data is read out in field units via the fourth field changeover switches 24 and 26 and the second frame changeover switch 28.

The output is selected by a recording and reproduction mode changeover switch 38. At the time of recording, an ID signal to be described later is supplied to the synthesizer 46, and a predetermined ID signal is added before and after the digital video signal. In this state, the ID signal is supplied to a rotating magnetic head device (not shown) to be recorded. You.

The digital video signal reproduced from the rotating magnetic head device is supplied to the memory circuit 40 through the above-mentioned plurality of switches, and the digital video signal read therefrom is converted into an analog signal by the D / A converter 60. It is converted and output to the output terminal 62.

Now, the above-mentioned video signal is supplied to the field discriminating circuit 42, where the odd and even fields are discriminated, and the output is supplied to the memory controller 44. The above-mentioned changeover switches 16 to 22, 24 to 28 and 38 provided at 40 are controlled. Therefore, the memory circuit 40 has a built-in CPU that functions as a control unit.

The field discrimination output output from the memory controller 44 and the bit signal synchronized with the bit of the digital video signal are supplied to the ID controller 48, where the ID addition instruction synchronized with the first bit or the last bit of the digital video signal is performed. A signal, an end flag and other signals are formed.

The ID addition instruction signal is supplied to the ID generation circuit 50, and the above-mentioned plurality of ID signals are sent out at a predetermined timing by a predetermined number of units and added to the digital video signal.

Then, an end flag is generated from the ID addition instruction signal. In this example, as shown in FIG. 3, the end flag EF is generated in synchronism with the end ID added especially to the rear end of the digital video signal of the even field.

The end flag EF is supplied to a mechanical microcomputer 52 for controlling a mechanical system of the apparatus, particularly, a recording / reproducing system, and various mode control signals synchronized with the end flag are formed, whereby the mechanical control system 54 is controlled. This end flag EF is used when designating the recording pause mode.

That is, as described at the beginning, a case where a predetermined video is recorded together with audio in a frame unit, and when the one-shot mode is selected, after a video of a certain frame is recorded, a video of a next predetermined frame is recorded. This is because, in order to record a video, the end of the video must be detected and the recording / reproducing system (including the mechanical system, the same applies hereinafter) must be automatically shifted to the recording pause mode immediately.

At the time of reproduction, a part of the reproduced digital video signal is supplied to the ID detection circuit 58 to separate the ID signal.
The separated ID signal is supplied to the memory controller 44, and the memory control during reproduction is executed. At the same time, in the ID detection circuit 58, an end flag EF corresponding to the even field is generated as shown in FIG.

Then, as in the case of recording, the reproduction of one video is completed (in units of frames) using the end flag EF, and at the same time, the mode automatically transitions to the reproduction pause mode.

 The recording pause mode is realized through the following steps.

That is, as shown in FIG. 4, the end ID is composed of, for example, p (1810 in this example) consecutive identification codes in units of parallel 8-bit identification codes. Recorded.

In this figure, m and n are integers, and n is p
It is assumed that it is located 50 before the p-th and m is located 150 before the p-th.

And the end flag obtained from the ID controller 48
When the end of recording of the p-th end ID is detected by the fall of the EF, the recording / reproducing system is controlled to the reverse mode.

At the same time, the number of end IDs recorded on a magnetic tape (not shown) is counted from the end.

When the count value reaches pm (for example, 150),
The recording / reproducing system is controlled to a reproducing mode. Even in the reproduction mode, the end ID is counted toward the p side. And p
When −n (for example, 50) is reached, the recording / reproducing system is controlled to the recording pause mode.

This recording pause mode is controlled by the end ID
Is not the end of However, since the tape running system has its inertia, the magnetic tape continues to run slightly by that, and then stops completely.

In the stopped state, the magnetic head comes to face the position almost at the end of the end ID. Therefore, the position of the end ID for designating the recording pause mode, that is, n is selected in consideration of the inertia of the tape traveling system.

If the mode control of the recording pause mode is performed on the basis of the end flag EF related to the entry ID as described above, there is no blank section in the recording mode.

In order to achieve such control, a control program for achieving the processing shown in FIG. 5 is stored in the mechanical microcomputer 52, and mode control is performed based on the control program.

In the processing flow 70 shown in FIG. 5, when the one-shot mode is selected, first, one frame of image data constituting the digital video signal is recorded (step 71). The ID is recorded (step 72).

Next, the last bit of the end ID is checked (step 73), and when the last bit is detected, the mode of the recording / reproducing system is controlled to be the reverse mode (step 74). Then, the reproduction end ID is a predetermined number (pm =
When it becomes 150), it transits to the reproduction mode (steps 75 and 76).

In this playback mode, the playback end ID is a predetermined number (n
When −m = 100), the mode transits from the reproduction mode to the recording pause mode (steps 77 and 78).

In the above, specific numerical values such as p, m, and n are only examples, and these may be changed depending on the inertia of the recording / reproducing system used.
The values of p, m, and n are different.

[Effects of the Invention] As described above, in the present invention, a predetermined identification signal is added to the end of a video signal for recording, and the recording pause mode is controlled on the basis of the identification signal during recording. Things.

According to this, even when recording a video in frame units as in the washoot mode, a predetermined video can be recorded without generating a blank section. Therefore, the recording density of the magnetic tape is improved, and the reproducing time is shortened accordingly.

[Brief description of the drawings]

FIG. 1 is a block diagram of an essential part showing an example of a digital audio tape recorder according to the present invention, FIG. 2 is a diagram showing an example of a data structure of one frame, FIG. 3 is an explanatory diagram of an end flag, and FIG. FIG. 5 is a diagram illustrating a mechanical control operation, FIG. 5 is a diagram illustrating a mechanical control processing flow, FIG. 6 is a diagram illustrating a signal format according to the present invention, and FIG. 7 is a diagram illustrating an operation during recording. 16 One-shot switch 18, 28 Frame switch 20-26 Field switch 38 Mode switch 40 Memory circuit 44 Memory controller 48 ID controller 50 ID generator 52 …… Mechanical microcomputer 54 …… Mechanical control system 58 …… ID detection circuit

Claims (1)

(57) [Claims] 1. A high-order M bits (M is an integer, N> M) of a digital signal composed of N bits (N is an integer)
Is assigned to the digital audio signal, and the remaining (N-
In a digital audio tape recorder in which a digital video signal is allocated to M) bits and a composite digital signal is recorded and reproduced in units of one frame, a predetermined digital signal is formed at the beginning and end of the composite digital signal constituting one screen. A digital audio tape recorder wherein an identification signal is inserted and recorded, and the recording / reproducing system is controlled to a recording pause mode using the identification signal inserted last.