JPH0397185A - Signal reproducing device - Google Patents

Abstract

PURPOSE:To output a time code signal whose biphase is correctly regulated by restricting an output time code frame reference signal within a prescribed time range where a predicted frame head is made as a center. CONSTITUTION:A frame prediction part 4 predicts the head of a next time code frame based on a time code reference clock signal. A frame reference signal restriction part 5 outputs the second output time code frame reference signal obtained by restricting the first output time code frame reference signal within the prescribed time range with respect to a time predicted by the frame reference signal prediction part 4 based on a frame prediction signal generated by the frame prediction part 4. A time code generation part 6 outputs the time code signal of a time code value based on the second output time code frame reference signal which is restricted within a prescribed range by the restriction part 5 and the time code reference clock signal. Thus, the regulation of the biphase of the time code signal is not disturbed and the correct time code signal is outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention provides a method for reproducing a time code having a frame period different from that of the recording time using a signal reproducing means having a frame reference signal. For example, a rotating head type digital audio tape recorder (hereinafter referred to as R
It is written as -DAT. This invention relates to a signal reproducing device for reproducing, for example, an SMPTE/EBU time code, which is a time code of a VTR, using a signal reproducing means as a signal reproducing means.

BACKGROUND TECHNOLOGY In recent years, digital technology has been applied to many fields such as audio and video, and CD players. Technologies such as R-DAT and digital VTR have been established. In this process, along with PCM signal recording and reproducing technology, a time code corresponding to the PCM signal is recorded and reproduced, and this time code is used to cue recording and playback, and by connecting multiple recording and reproducing devices, synchronous recording and synchronization are possible. Time code recording and playback technology that performs playback and synchronized editing has become important.

Conventionally, SMPTE/EBU time codes have been widely used as time codes in broadcast equipment such as VTRs. This SMPTE/EBU time code usually consists of a bit string consisting of 80 bits per frame.
Bi-phase modulated signals are used for connections between devices. In order to record and reproduce SMPTE/EBU time code using a rotating head using a signal recording and reproducing device such as R-DAT, which has a different frame frequency from SMPTE/EBU time code, in order to enable connection with conventional equipment. In addition to the time code, it was necessary to record and reproduce information representing the time relationship between the time code frame and the frame of the signal recording and reproducing device. For example, there is a rotary head type recording/reproducing device as disclosed in Japanese Patent Application Laid-Open No. 63-29391.

An example of a conventional signal recording/reproducing device will be described below.

FIG. 4 shows a block diagram of this conventional signal recording/reproducing apparatus. The parts surrounded by dotted lines indicate the signal recording device and the signal reproducing device, respectively. First, the signal recording device will be explained. In FIG. 4, 41 is a signal recording/reproducing section, for example, R-DAT 142 is a time code reading section that reads, for example, an SMPTE time code, and 43 is a phase information detecting section.

The operation of the signal recording device configured as described above will be explained below.

The time code reading unit 42 reads an input time code having a first frame period, outputs a recording time code value, and also reads an input time code frame reference signal which is a frame reference signal of the input time code having a first frame period. Output. The phase information detection section 43 outputs recording phase information from the input time code frame reference signal output from the time code reading section 42 and the recording/reproducing frame reference signal which is the frame reference signal of the signal recording/reproducing section 41 . Here, the phase information represents the time from the recording/reproducing frame reference signal corresponding to the beginning of the frame of the signal recording/reproducing section to the input time code frame reference signal corresponding to the beginning of the preceding time code frame. be. A to E in FIG. 5 are waveform diagrams showing the operation of the phase information detection section 43, where A is an input time code frame, B is an input time code frame reference signal,
C is the count of the counter of the phase information detection section 43, D is the recording/reproduction frame reference signal, and E is the recording frame. As shown in FIG. 5, the counter in the phase information detection unit 43 is reset at the rising edge of the first frame synchronization signal B and starts counting from O, as shown in C. The counter value is read at the rising edge. This counter is, for example, a counter that makes exactly 1000 counts per input time code frame period, and in the example shown in this figure, 2 is output as the recording phase information. The signal recording/reproducing section 41 records recording time code values, recording phase information, and recording signals at the recording/reproducing frame period.

The portion surrounded by dotted lines as the signal reproducing device in FIG. 4 shows a block diagram of a conventional signal reproducing device. Fourth
In the figure, 41 is a signal recording/reproducing unit, for example, R-DAT.
144 is a time code generation section that outputs, for example, an SMPTE time code, 45 is a time code frame reference signal generation section, and 46 is a time code clock generation section.

The operation of the signal reproducing device configured as described above will be explained below.

The signal recording/reproducing section 41 reproduces the time code value, phase information, and reproduction signal. The time code frame reference signal generation section 45 performs an operation opposite to that of the phase information detection section 43 described in connection with the signal recording device.

That is, reproduction phase information is set at the rising edge of the second frame reference signal in a counter that reaches its maximum value at the same frame period as the input time code signal. This counter outputs a pulse at the moment the counter reaches O from its maximum value. In this way, an output time code frame reference signal is generated that has the same phase relationship as the input time code frame reference signal during recording and the recording/reproducing frame reference signal. In the time code generation unit 44, the time code clock generation unit 46
An output time code signal having a time code value reproduced from the signal recording/reproducing section 4l is generated based on the time code reference clock generated by the signal recording/reproducing section 4l.

In addition, the time code generation section 44 and time code clock generation section 46 are reset at the beginning of each frame using the output time code frame reference signal, and by aligning the beginning of the frame, the time between the input time code signal and the recording signal during recording can be changed. A reproduction signal and an output time code signal having the same time relationship as the relationship are output.

FIG. 6 is a timing chart explaining the reset of the output time code, where F is the output time code frame reference signal, G is the time code reference clock, and H is the output time code signal. As shown in the figure, the output time code signal H and the time code reference clock G are reset at the beginning of each frame by the output time code frame reference signal F and are output.

Problems to be Solved by the Invention However, in the conventional signal reproducing device described above, when a fixed head records and reproduces a time code with a jib, such as a time code recorded in the longitudinal direction of a tape, the time code frame signal Since the frame is reset at an arbitrary position, if you try to output timecode with a jitter larger than the timecode clock cycle, it will disturb the regularity of the timecode bi-phase pattern and cause the correct time to be output. There was a problem that a code signal could not be output.

FIG. 7 is a waveform diagram for explaining this, and ■ indicates three timing examples a, b, and of the output time code frame reference signal when focusing on one frame.
It shows c. These a, b. c shows three examples of the pulse at the beginning of the next frame relative to the pulse at the beginning of the frame of interest. a is the timing corresponding to just one frame of the output time code signal created by the time code reference clock, and b is the timing when the currently focused frame length is recorded short due to jitter etc. In the reproduced example, C is an example in which the data was recorded for a long time. J is the output time code for the timing example of a, K is the output time code for the timing example of b,
L indicates the output time code at the timing example of C.

When the output time code frame reference signal is output at point a, as shown at J, the output time code frame signal is Even if the reset is performed at the beginning of the frame, the correct output time code signal will be output as if it were not reset. In case b, the final data 111 of the frame is lost due to the reset as shown in K, resulting in an abnormally long IHI level portion. In the case of C as well, as shown in L, the data 10'' at the beginning of the frame is abnormally long and is no longer a correct biphase pattern.

With output time code signals such as K and L, correct time code values cannot be read by other devices.

The present invention solves the above-mentioned conventional problems.When a time code with jitter is recorded, such as a time code recorded in the longitudinal direction of a tape with a fixed head, and this is played back, the frame of the time code is It is an object of the present invention to provide a signal reproducing device that can output a correct time code signal without disturbing the pi-phase rules of the time code signal due to jitter.

Means for Solving the Problems To achieve this object, the signal reproducing device of the present invention includes a signal reproducing means for outputting a time code value, phase information, and a reproduced frame reference signal, and a signal reproducing means for outputting a time code value, phase information, and a reproduced frame reference signal, and a signal reproducing means for outputting a time code value, phase information, and a reproduced frame reference signal, and a time code frame reference signal generator for outputting a first output time code frame reference signal from the . a time code clock generating means for generating a time code reference clock signal for generating an output time code signal; and a time code clock generating means for generating a time code reference clock signal for generating an output time code signal; a frame prediction means for generating a frame prediction signal by predicting the beginning of the frame; and a second output time code frame reference signal that limits the first output time code frame reference signal to within a predetermined time range based on the frame prediction signal. It has frame reference signal limiting means for outputting, and time code generation means for generating an output time code signal of a time code value from the second output time code frame reference signal and the time code reference clock signal.

Effect: With the above-described configuration, the signal recording device of the present invention limits the first output time code frame reference signal within a predetermined time range based on the frame prediction signal created by the frame prediction means, and outputs the second output time code frame. Since a reference signal is created and the output time code signal is generated based on this signal, the bi-phase rule of the time code signal is not disturbed by frame jitter of the time code, and the correct time code signal can be output. can.

EXAMPLE An example of the present invention will be described below with reference to the drawings.

FIG. 1 shows a block diagram of a signal reproducing device in one embodiment of the present invention. In FIG. 1, 1 is a signal reproducing unit such as R-DAT, 2 is a time code frame reference signal generating unit, 3 is a time code clock generating unit, 4 is a frame prediction unit, 5 is a frame reference signal limiting unit, 6 is a time code generation section.

The operation of the signal reproducing apparatus of this embodiment configured as described above will be described below.

It is assumed that seven time code values, phase information, and recording signals are recorded on the signal recording medium by a signal recording device as described in the conventional example.

The signal reproducing unit 1 outputs a time code value, phase information, and a reproduced signal at the cycle of the reproduced frame reference signal. The time code frame reference signal generating section 2 outputs a first output time code frame reference signal from the reproduced frame reference signal and phase information output from the signal reproducing section 1 in the same manner as a conventional signal reproducing device. . The time code clock generator 3 generates a time code reference clock signal for generating time codes. The frame prediction unit 4 predicts the beginning of the next time code frame based on the time code reference clock signal. Frame reference signal limiter 5
is a second output time code frame in which the first output time code frame reference signal is limited within a predetermined time range with respect to the time predicted by the frame reference signal prediction unit by the frame prediction signal generated by the frame prediction means. Outputs the reference signal. The time code generation unit 6 outputs a time code signal of a time code value from the second output time code frame reference signal and the time code reference clock signal which are limited to a certain predetermined range by the frame reference signal restriction unit 5. .

FIG. 2 is a detailed block diagram of this embodiment.

In FIG. 2, the same block numbers as in FIG. 1 correspond to those in FIG. Incidentally, the rising edge detection section 21, the falling edge detection section 22, and the timing determination section 23 use the frame reference signal restriction section 5, the time code pattern generation section 24, and the biphase modulation section 25.
constitutes a time code generation section e.

The signal reproducing unit 1 reproduces the reproduced signal, time code value, and phase information. The time code frame reference signal generating section 2 generates a first output time code frame reference signal from the phase information and the reproduced frame reference signal in exactly the same manner as in the conventional example. The time code clock generating section 3 generates a time code reference clock having a period that equally divides the frame period of the output time code signal into 160 equal parts, for example.

Based on the time code reference clock, the frame prediction unit 4
As a frame prediction signal, 1 for a time period of l clocks of the time code reference clock centered around the beginning of the predicted frame.
Generates a signal that becomes “H”. Rising edge detection unit 2
1 outputs a rising edge signal at the rising edge of the frame prediction signal, and the falling detection section 22 outputs a falling edge signal at the falling edge of the frame prediction signal. The timing determination section outputs a rising edge signal as a second output time code frame reference signal when the first output time code frame reference signal rises before the rising edge signal.

Further, if the frame prediction signal is within the period of 4 H l at the rising edge of the first output time code reference signal, the first output time code reference signal is output as is as the second output time code reference signal. Furthermore, if a falling edge signal is input before the first output time code frame reference signal rises, the falling edge signal is output as the second time code frame reference signal.

The second output time code frame reference signal is input to the frame predictor and time code pattern generator and is reset. Further, the time code pattern generation unit 24 generates a time code pattern of the output time code according to the second time code frame reference signal. The bi-phase modulation unit 25 bi-phase modulates the time code pattern using the time code reference clock and outputs an output time code signal of a reproduced time code value in synchronization with the second output time code frame reference signal.

FIG. 3 is a timing chart for explaining the operation. M is the first output time code frame reference signal, N is the time code reference clock signal, O is the frame prediction signal, P is the second output time code frame reference signal, and Q is the output time code signal.

Three frame heads are shown in the figure, which correspond to timing examples a, b, and c in FIG. 7 from the left, respectively. In a, g }l of the frame prediction signal O
Since the first output time code frame reference signal is output within the period I, the first output time code frame reference signal is output as is as the second output time code frame reference signal. In b, since the first output time code frame reference signal comes before the rising edge of the frame prediction signal 0, the second output time code frame reference signal is limited to the rising edge portion of the frame prediction signal O. In contrast, in C, since the first output time code frame reference signal M comes after the falling edge of the frame prediction signal O, the second output time code frame signal P is output at the falling edge portion. By resetting the output time code using the thus limited second output time code frame reference signal P as a reference, it is possible to output a time code signal with a correct bi-phase rule as shown in Q.

As described above, according to this embodiment, by providing the timing determination section, the time code generation section 6 is synchronized with the output time code frame reference signal limited only within a certain time window, and the time code pattern This prevents a reset from occurring during the process, allowing the correct output timecode signal to be output.

Effects of the Invention As described above, in the signal reproducing apparatus of the present invention, by providing the time code frame prediction means and the time code reference signal limiting means, the frame start of the next frame of the output time code signal is predicted, and the predicted frame is By limiting the output timecode frame reference signal to a predetermined time range centered on the beginning, it is possible to output a timecode signal with the correct bi-phase rule, and to avoid timecode reading errors. It is possible to synchronize audio and video and reduce errors when editing.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a signal reproducing device in one embodiment of the present invention, FIG. 2 is a detailed block diagram of the signal reproducing device in the same embodiment, FIG. 3 is a timing chart showing the operation of the same embodiment, and FIG. FIG. 4 is a block diagram of a conventional signal recording and reproducing device, FIG. 5 is a timing chart showing the operation of the phase measuring section of the conventional example, FIG. 6 is a timing chart showing the operation of the conventional signal reproducing device, and FIG. is a timing chart for explaining operational problems of the conventional example. DESCRIPTION OF SYMBOLS 1... Signal reproduction part, 2... Time code frame reference signal generation part, 3... Time code clock generation part, 4... Frame prediction part, 5... Frame reference signal restriction part, 6. ...Time code generation section.

Claims (1)

[Scope of Claims] Signal reproducing means for outputting a time code value, phase information, and a reproduced frame reference signal; and a timer for outputting a first output time code frame reference signal from the reproduced frame reference signal and the phase information. code frame reference signal generation means; time code clock generation means for generating a time code reference clock signal for generating an output time code signal; and from the time code reference clock signal and a second output time code frame reference signal. , a frame prediction unit that generates a frame prediction signal that predicts the beginning of the next time code frame; and a second frame prediction unit that limits the first output time code frame reference signal to within a predetermined time range based on the frame prediction signal. frame reference signal limiting means for outputting an output time code frame reference signal of the second output time code frame reference signal; and a time code for generating an output time code signal of the time code value from the second output time code frame reference signal and the time code reference clock signal. A signal reproducing device comprising a generating means.