JP2666348B2 - Playback device - Google Patents

Description

A. Field of the Invention The present invention reproduces a time code signal and a control signal recorded in the longitudinal direction of a magnetic tape, and controls and reproduces time code data read from the time code reproduction signal. The present invention relates to a reproducing apparatus that performs correction using a signal.

B. Summary of the Invention The present invention reproduces a time code signal and a control signal recorded on a longitudinal track on a magnetic tape, and when the reproduced time code signal has an error, corrects the error using the control signal. Detecting means for detecting whether a time code signal has been read and reading the time code from the time code signal to generate time code data when the time code signal has been read; Counting means for performing a counting operation based on the obtained control signal, arithmetic means for obtaining difference data corresponding to a difference between output signals of the counting means at predetermined time intervals, time code data and difference data being input, and the time code The continuity of the time code is determined by comparing the data with the difference data. Determining means for determining that the reproduced time code signal could not be read based on the detection result of the detecting means, the time code data read before the period corresponding to the predetermined period is added to the time code data. The difference data obtained by the arithmetic means is added or subtracted, and the addition or subtraction result is used as the time code data at the position where the time code signal is reproduced, and the determination means determines that there is no continuity of the time code data. When
The difference data is added or subtracted to the time code data read before a period corresponding to the predetermined period, and the result of the addition or subtraction is determined by the determination unit until the time code data is determined to have continuity. By using the time code data at the position where the time code signal is reproduced, good correction of the time code signal can always be performed regardless of the running speed of the magnetic tape.

C. Prior Art Conventionally, in a magnetic tape used as a recording medium in a reproducing apparatus such as a video tape recorder, the position reference of each of a plurality of information signal recording tracks for performing so-called oblique recording on the magnetic tape is used. A CTL track for recording a control (CTL) signal is provided in the longitudinal direction, that is, along the running direction of the magnetic tape.
When recording an information signal, the C
The TL signal is recorded, and during the reproducing operation, the control of the running of the magnetic tape and the detection of the position on the magnetic tape are performed based on the CTL reproducing signal.

Further, in the magnetic tape editing device, etc., it is necessary to detect the tape position of the recorded magnetic tape with high accuracy, so that a time code signal serving as an address signal is recorded in advance on the magnetic tape, Editing is performed while reading the time code signal. As the time code, a longitudinal time code (so-called LT) recorded along the running direction of the magnetic tape is used.
C) a signal and a vertical section time code (so-called VIT) recorded on the information signal recording track every period of a predetermined cycle.
C) signal, which includes address information indicating hours, minutes, seconds, and frame numbers, and is recorded by, for example, a bi-phase code.

By the way, since the above-mentioned LTC signal is read based on the so-called zero-cross point, when the running speed of the magnetic tape is switched, or when the running speed is low, the influence of so-called jitter becomes large, so that the reading cannot be performed correctly. There is.

In such a case, there has been proposed a reproducing apparatus that corrects the LTC reproduced signal with the CTL reproduced signal. That is, in the reproducing apparatus, when the reading of the LTC signal becomes impossible, the mode is switched to a mode for reading the CTL signal, and the LTC reproducing signal read immediately before the switching is obtained by counting the CTL reproducing signal. The relative tape position data is added or subtracted.

D. Problems to be Solved by the Invention By the way, in the above-described reproducing apparatus in which the correction is performed using the LTC signal ぽ CTL signal, the phase relationship between the completion of the reading of the LTC signal and the counting of the CTL signal is described. But,
For example, it may fluctuate due to so-called fu / flutter or the like accompanying the running of the magnetic tape, and the above-mentioned LTC reproduction signal may not be accurately corrected. That is, as shown in FIG.
When the phase of the CTL signal is behind the phase of the C signal, the seventh
7A, between the recording position indicating the end of the Nth frame obtained by the LCT signal indicated by l _n and the recording position indicating the end of the Nth frame obtained by the CTL signal indicated by c _n in FIG. 7A. at position y _a, when switched from a read mode of the LTC signal to a mode for reading the CTL signal, the frame number will be incremented at the position of both the above positions Ln and Cn. Then, in the data finally displaying the frame number, the position l _n is correctly treated as the end position of the Nth frame, but the position c _n is treated as the end position of the (N + 1) th frame. Incorrect numbers are displayed.

Further, as shown in FIG. 7 B, when the phase of the CTL signal is advanced with respect to LTC signal, CTL indicated by FIG. 7 B in c _n
And recording the position indicating the end of the N-th frame obtained by the signal, at the position y _B between the recording position indicating the end of the N-th frame obtained by LCT signal shown in FIG. 7 B in l _n,
When the mode is switched from the LTC signal reading mode to the CTL signal reading mode, the frame number is not incremented at any of the positions l _n and c _n . Then, in the final frame number data, the above CTL
The end position c _{n + 1 of} the (N + 1) th frame obtained from the signal is
It is treated as the end position of the Nth frame, and an error occurs in the display of the frame number.

In order to solve such a problem, in the time code correction circuit described in Japanese Patent Application No. 62-70969, which has been proposed by the present applicant, completion of reading of the LTC signal is determined by the CTL signal. Detected that it was late for reading
The count data of the CTL signal used in the above-described LTC signal correction processing is corrected.

However, in this time code correction circuit, a signal processing device (CPU) that performs correction processing of the LTC signal in order to detect a change in the phase relationship between the LTC signal and the CTL signal.
When the reading of the LTC signal is completed, the CTL signal is read by so-called interrupt processing. Therefore, when the magnetic tape runs at a high speed, there is a problem that the interrupt processing cannot follow the running of the magnetic tape, and the LTC signal cannot be corrected properly.

Accordingly, the present invention has been proposed in view of the above-described circumstances, and has as its object to provide a reproducing apparatus capable of always performing good correction of an LTC signal regardless of a running speed of a magnetic tape.

E. Means for Solving the Problems In order to solve the above problems and achieve the above objects, the present invention provides a method for reproducing a time code signal and a control signal recorded on a longitudinal track on a magnetic tape and reproducing the time. When the code signal has an error, in the reproducing apparatus adapted to correct the error using the control signal, it is detected whether or not the time code signal is read, and when the time code signal is read, the time code is read. Detecting means for reading time code from the signal to generate time code data; counting means for performing a counting operation based on the reproduced control signal; and difference data corresponding to the difference between the output signals of the counting means at predetermined intervals. Calculation means for obtaining the time code data and the difference data, And determining means for comparing the difference data with the difference data to determine the continuity of the time code, and when it is determined that the reproduced time code signal could not be read by the detection result of the detecting means, The difference data obtained by the arithmetic means is added or subtracted from the time code data read before the period corresponding to the predetermined period, and the addition or subtraction result is used as the time code at the position where the time code signal is reproduced. Data, and when the determination means determines that there is no continuity of the time code data,
The difference data is added or subtracted to the time code data read before a period corresponding to the predetermined period, and the result of the addition or subtraction is determined by the determination unit until the time code data is determined to have continuity. It is characterized in that it is time code data at a position where a time code signal is reproduced.

F. Operation In the reproducing apparatus according to the present invention, difference data corresponding to the difference between the output signals of the counting means operating based on the control signal is obtained by the arithmetic means at predetermined intervals, and the reproduced time code If it is determined that the signal could not be read, the difference data obtained by the arithmetic means is added or subtracted from the time code data read before the period corresponding to the predetermined period, and the addition or subtraction result is used as the time. The time code is treated as time code data at the position where the code signal is being reproduced, and when the determination means determines that there is no continuity of the time code data, the time code read before the period corresponding to the predetermined period If the error code data is added or subtracted from the data and the result of the addition or subtraction is determined by the determination means to be continuous with the time code data. Since it handled as time code data at the position where the time code signal is reproduced until it is a constant, the time code data is corrected.

G. Examples Hereinafter, specific examples of the present invention will be described with reference to the drawings.

The reproducing apparatus according to the present invention is configured to reproduce a signal recorded on a magnetic tape 1 as shown in FIG. As described above, a predetermined information signal such as a video signal is so-called diagonally recorded on the information signal recording track of the magnetic tape 1 and a time code track provided along the longitudinal direction of the magnetic tape 1 as described above. (LT
C track) and control track (CTL track)
Corresponding to the longitudinal time code (so-called LT
C) signals and control (so-called CTL) signals are recorded.

The magnetic tape 1 has an LTC head 2 and a CTL head 7
Are brought into sliding contact with the respective predetermined positions. The LCT head 2 reads an LTC signal from an LTC track on the magnetic tape 1 and sends the LTC reproduced signal to a waveform shaping circuit 4 via a head amplifier 3. The waveform shaping circuit 4 performs a pulse shaping process on the LTC reproduced signal by performing a waveform shaping process.
A C reproduction signal is generated and sent to a time code reading circuit (decoder) 5. The decoder 5 includes the waveform shaping circuit 4
A decoding process is performed on the pulsed LTC reproduction signal sent from the microcomputer to read the time code indicated by the LTC reproduction signal, generate time code data _DT , and perform signal processing as arithmetic means detecting means and determining means. It is supplied to the device (CPU) 6.

Then, the CTL head 7 controls the CTL of the magnetic tape 1.
The CTL signal is read from the track, and the CTL reproduction signal is sent to the waveform shaping circuit 9 via the head amplifier 8. The waveform shaping circuit 9 performs a waveform shaping process on the CTL signal to generate a C signal.
CTL counter 1 generates a TL pulse signal P _C, the counting means
Send to 0 and CPU6 above. The CTL counter 10 is
Count data by counting signals
It generates a D _C sent to the CPU 6.

The CPU 6 is connected to the magnetic tape 1 via a predetermined magnetic tape drive (not shown) via an input terminal 11.
The tape running switching signal _SD indicating the running direction of the tape running is supplied. Furthermore, the above CPU6, the operation instruction pulse P _A from the timer 12 at a predetermined period is supplied. The predetermined period is, for example, one frame (so-called 1 / 2VD) period when the information signal is a video signal.

Then, the CPU6 is counted by subtracting reads the count data D _C at a predetermined cycle corresponding to the operation instruction pulse P _A, the count data D _C which read the last from the count data D _C freshly read It calculates a difference data [Delta] D _C. Further, the CPU 6 reads the time code data _DT at the predetermined cycle, and continuously repeats a predetermined operation as shown in the flowchart of FIG. 2 so as to be finally used. and outputs the Do corrected time code correction data AD _T.

That is, when the playback device is started, the CPU 6
Starts the above-mentioned predetermined operation. In step st1 in FIG. 2, it is checked whether or not the magnetic tape 1 is mounted on the reproducing apparatus. If the magnetic tape 1 is mounted, the process proceeds to step st2. If so, proceed to step st9.

Unless the magnetic tape 1 is mounted, in step st9, the flag [R _D T _C DN] "0" is set, the process proceeds to step st10. The flag [R _D T _C DN] is a flag which the LTC signal becomes "1" when it was read without error by the decoder 5.

In step st10, set to "0" in the flag [Gett _C F], the program ends. This flag [GetT
_C F], in the CPU6, to "1" when the time code data D _T that is generated is sent to the CPU6 by the decoder 5 is in a state no errors so can be adopted as the reference value of the time code data Is a flag.

Then, when the magnetic tape 1 is mounted and the reproduction mode is set, in step st2, it is checked whether or not the recording mode is readable by the LCT signal reproducing device. If not, the process proceeds to step st11.

At step st3, the decoder 5 controls the LTC
It is determined whether or not the signal has been read without error. If the signal has been read, the process proceeds to step st4. If the signal has not been read, the process proceeds to step st11.

In step st4, the time code data D _T
Is read into the CPU 6 and the process proceeds to step st5.

In step st5, sets "1" in the flag [R _D T _C DN], the process proceeds to step st6.

In step st6, checks whether the flag [Gett _C F] is "0", if "0", step st7
If it is not "0", that is, if it is "1", the process proceeds to step st13. The reproduction at the beginning of mounting the magnetic tape 1 in the apparatus, for in step st10 before mounting the magnetic tape 1 the flag to [Gett _C F] is "0" has remains set When the magnetic tape 1 is attached and the process first proceeds to step st6, the process always proceeds to step st7.

In step st7, the time code data _DT read into the CPU 6 is set in the buffer [C _TT ], and the process proceeds to step st8. The value of the buffer [C _TT] becomes the time code correction data AD _T output from the CPU6 as data representing the current position, for example, time of the magnetic tape 1.

In step st8, sets "1" in the flag [Gett _C F], the program ends. Therefore,
Since through this step st8, that is, if the process proceeds to step st6 secondly or later after fitting the magnetic tape 1 is always the flag [Gett _C F] has become a "1", The process proceeds from step st6 to step st13.

Then, in step st11, set to "0" in the flag [R _D T _C DN], the process proceeds to step st12.

In step st12, checks whether the flag [Gett _C F] is "1", if "1" the process proceeds to step st13, if not "1", i.e., "0" program To end. In this step st12, the the flag [Gett _C F] is "0", the magnetic tape 1
Is not in the mode in which the readout of the LTC signal by the reproducing apparatus is impossible (ie, the case where the step has not proceeded to the step st8 at least once since the device is mounted, that is, the case where the step has not proceeded to the step st6). Whether the LTC signal has not been read by the decoder 5 without any error since the magnetic tape 1 was mounted (when the process proceeds from the step st2 to the step st11) (when the process proceeds to the step st11 from the step st3) ).

In step st13, checks whether the flag [R _D T _C DN] is "1", "1" Otherwise, ie the process proceeds to step st14 If "0", there is "1" If so, proceed to step st15. In this step st13, the flag [R _D T _C DN] is a "0" and if the process proceeds from step st13 to step st14 is a case that has gone through the steps st11, the time code data D _T reading of the case are made at least once (step st7) could not read the LTC signal thereafter (step st2 or step st3). Also,
In this step st13, the flag [R _D T _C DN] is a "1" and if the process proceeds from step st13 to step st15 is a case that has gone through the steps st6, the time code data At least 1 reading of _DT
The time has been completed (step st7), and the time code data _DT is further read after that (step st4).

In step st14, the new values to the value obtained by adding or subtracting the count difference data [Delta] D _C of the buffer [C _TT] was set in the buffer [C _TT], the program ends. This operation will be the value of the time code D the buffer is determined by _T [C _TT], are determined based on the count data D _C when the above-mentioned time code D _T is successfully read, Above time code D _T
The corrected by the counter data D _C can be assumed to be generating the time code correction data AD _T. Whether to add or subtract the count difference data ΔD _C to or from the value of the buffer [C _TT ] is determined based on the tape running switching signal _SD .

In step st15, it is checked whether or not the reproducing apparatus is in a mode in which the magnetic tape 1 runs at a higher speed than the reproducing mode, such as a so-called fast forward (FF) mode or a rewind (REW) mode. If the mode is set, the process proceeds to step st22. If the mode is not set to the high-speed running mode, the process proceeds to step st16.

In step st16, the time code data D _T is compared by comparing the value obtained by adding or subtracting the counter difference data ΔD _C to the value of the buffer [C _TT ] at this time with the time code data D _T. The continuity of the data is checked, and the reliability of the data is checked. If they match the result of the comparison, based on the value of the buffer before a predetermined cycle based on the operation instruction pulse P _A [C _TT], the moving distance of the magnetic tape 1 is detected by the count data D _C Thus, the continuity of the value relatively formed by the above confirms the continuity of the read time code data _DT . In this case, the the reliability of the time code data D _T was confirmed in the accuracy of the count data D _C, the flow proceeds to step st22. If the result of the comparison does not match, it is determined that the reliability of the time code data _DT has been denied, and the process proceeds to step st17.

In step st22, the time code data _DT is set in the buffer [C _TT ], and the flow advances to step st23. The process proceeds to step st22 when the reliability of the time code data _DT is confirmed in step st16 or when the magnetic tape 1 is in a mode in which the magnetic tape 1 runs at a high speed. . In the case of the high-speed running mode, the time code data _DT obtained from the LTC signal is reliable data. That is, as described above, it is difficult to read the LTC signal when the running speed of the magnetic tape 1 is low, and when the running speed is high (for example, about 30 to 60 times the reproduction mode). On the contrary, the reliability of reading is increased.

In step st23, the error counter [T _C D _L T] for recording the number of times of the correction of the time code D _T by same the count data D _C as in the step st14 performed in step ST17 "0" And set
Quit the program.

Step In ST17, similarly to the step st14, the value in the count difference data [Delta] D _C newly above buffer plus or minus a [C of the buffer [CTT]
_TT ], and proceeds to step st18.

In step ST18, the error counter [T _C D _L
It is checked whether or not [T] is a predetermined value x. If the value is the predetermined value x, the process proceeds to step st19. If the value is not the predetermined value x, the process proceeds to step st21. The error counter [T _C D _L T] is for recording the number of correction of the time code data D _T by the count data D _C in step ST17, initially operations are made with 9 "0" . The predetermined value x is set in advance, for example, as x = 2 in consideration of, for example, the traveling speed of the magnetic tape 1.

In step st21, the error counter [T _C D _L
Adding "1" to the value of T], the program ends is set to the error counter [T _C D _L T] as a new value.

In step st19, the time code data D _T
Is set in the buffer [C _TT ], and the process proceeds to step st20. By the time has progressed in this step ST19, should correct the time code data D _T by the count data D _C in step st17 is performed by a predetermined number of times corresponding to the predetermined value x (for example, three times) because there is because exit the correction employing the D _T of the time code data at this time as the time code correction data AD _T.

In step st20, the error counter [T _C D _L
T] is set to “0” and the program ends.

Note that the operation of the CPU6 as described above, and the LTC signal and the CTL signal, taking into account the phase difference between the predetermined information signals such as a video signal, a predetermined with respect to the operation instruction pulse P _A It may be executed with a time difference. That is, in the case of a video tape recorder, the phase difference between the CTL signal and the video signal can be changed by so-called tracking adjustment.
The maximum value of this adjustment is about 12 ms. Therefore, in this case, it is preferable that the operation such as reading of the data of the CPU 6 is executed at a time about 12 ms after the reference edge of the 1/2 VD.

In the reproducing apparatus according to the present invention configured as described above, when the magnetic tape 1 is mounted and the reproduction mode is set, the reading of the LTC signal is performed. When the LCT signal is in a readable mode and is normally read, and the time code data _DT generated based on the read LCT signal has continuity, or When the reproducing apparatus is in a mode in which the magnetic tape 1 is run at a high speed, it is determined that the reproducing apparatus has reliability.
The time code data D _T is output as the time code correction data AD _T (step st22 in Fig. 2).

At this time, as shown in FIG. 3, the running distance of the magnetic tape 1 and the change of the time code data _DT have a constant and continuous relationship.

Time code correction data AD _T at this time is used in such displays on a predetermined display means, not shown.

Thereafter the error has occurred in reading of the LTC signal, when no can do normal read, the time code correction data AD _T is generated and output based on the count data D _C (FIG. 2 Middle step st1
Four).

At this time, as shown in FIG. 4, the running distance of the magnetic tape 1, the time code data D _T is in a state of interrupted halfway, but is supplemented by the count data D _C during this period , The above time code correction data AD
_T changes are maintained in a constant, continuous relationship.

As shown in FIG. 5, the reading of the LCT signal was performed without error. However, when the time code data _DT based on the read LCT signal is not continuous and lacks reliability, a predetermined number of times is required. Over time code correction data
AD _T is generated and output based on the count data D _C (step st17 in Fig. 2), the continuity of the time code correction data AD _T is maintained. Incidentally, even in the middle of the predetermined number of times, when the reliability of the time code data D _T is confirmed in step st16, the time code data D _T is the time code correction data AD _T
(Step st22 in FIG. 2).

If the LTC signal is in a mode in which reading is not possible, or if the reading of the LTC signal has a large number of errors and cannot be read even once, the time code correction data AD
_T is not generated (ends at step st12 in FIG. 2).

When such a reproducing apparatus is applied to, for example, a video tape editing apparatus, a tape position where reliable time code data _DT cannot be obtained as described above is also used.
Using the time code correction data AD _T, it is possible to specify a so-called in-point and out-point, etc., can be performed accurately editing operation.

By the way, as shown in FIG. 6, at the positions before and after the position indicated by arrow _Z in FIG. 6 where the time code data D _T has lost continuity, the time code data D _T Although it has continuity, the time code data _DT at each position is
When the data changed (extended in FIG. 6) changed according to the traveling distance of the vehicle do not coincide with each other,
The time code correction data AD _T (F) when the magnetic tape 1 runs in the forward direction does not match the time code correction data AD _T (R) when the magnetic tape 1 runs in the reverse direction. . Then, these two time code correction data AD _T (F) and AD _T (R) are located on the rear side of the discontinuous position of the time code data D _T indicated by the arrow _z in the tape running direction in each case. , Have discontinuous points j _F and j _R where the data changes rapidly.

Even in such a case, the magnetic tape 1 is caused to travel in the forward direction and the time code correction data AD _T (F)
The Kang Songs corrected position by the data D _C specified as the in-point and out-point, etc., the position is reversely running the magnetic tape 1 the time code correction data by
When searching by AD _T (R), the time code correction data AD _T (F), AD _T (R) at the discontinuous points j _F , j _R
It is only necessary to cause an error corresponding to the amount of change in the data, and the magnetic tape 1 may run after passing a specified point greatly or stop at a position greatly deviated from the specified point. Is prevented.

H. Effects of the Invention As described above, in the reproducing apparatus according to the present invention, difference data corresponding to the difference between the output signals of the counting means operating based on the control signal is obtained by the arithmetic means at predetermined intervals. If it is determined that the reproduced time code signal could not be read, the difference data obtained by the arithmetic means is added or subtracted to the time code data read before the period corresponding to the predetermined period. Treat the addition or subtraction result as time code data at the position where the tie code signal is reproduced,
When the determination means determines that the continuity of the time code data is not present, the difference data is added or subtracted to the time code data read before a period corresponding to a predetermined period, and the addition or subtraction result is obtained. Is treated as time code data at a position where the time code signal is reproduced until the determination means determines that the time code data has continuity, thereby correcting the time code data.

That is, in the reproducing apparatus according to the present invention, since the time code signal and the control signal are always independently read from each other, a good time code is always obtained irrespective of the phase relationship between the signals and the running speed of the magnetic tape. It is possible to provide a reproducing apparatus capable of correcting a signal.

Further, according to the present invention, even at a discontinuous point of the table of the time code signal or a missing point of the signal, for example, an editing operation or the like can be accurately performed using the corrected time code data.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a reproducing apparatus according to the present invention, and FIG. 2 is a flowchart for explaining an operation of a signal processing apparatus constituting the reproducing apparatus. FIG. 3 is a graph showing the relationship between the running of the magnetic tape and the change of the time code data, and FIG. 4 is a graph showing a state where the reproducing apparatus corrects the time code data when the time code data is missing. FIG. 5 is a graph showing a state in which the reproducing apparatus corrects time code data when the time code data is discontinuous.
The figure is a graph showing another example of a state where the playback device corrects time code data when the time code data is discontinuous. FIGS. 7A and 7B are timing charts showing a state in which an error occurs in time code data in the conventional reproducing apparatus. FIG. 7A shows that the phase of the time code signal is ahead of the phase of the control signal. FIG. 7B shows a case where the phase of the time code signal is behind the phase of the control signal. 1 magnetic tape 5 time code reading circuit 6 signal processing device 10 CTL counter D _T time code data D _C count data AD _T time code correction data P _A operation instruction Pulse S _D …… Tape running switching signal

Claims (1)

(57) [Claims] A time code signal and a control signal recorded on a longitudinal track on a magnetic tape are reproduced, and when the reproduced time code signal has an error, the error is corrected using the control signal. A reproducing means for detecting whether or not the time code signal has been read, and detecting a time code from the time code signal to generate time code data when the time code signal has been read; Counting means for performing a counting operation based on the control signal; calculating means for obtaining difference data corresponding to a difference between output signals of the counting means at predetermined intervals; and inputting the time code data and the difference data. Comparing the time code data with the difference data, Determination means for determining the continuity of the data, and when it is recognized that the reproduced time code signal could not be read based on the detection result of the detection means, the read time code signal is read before a period corresponding to the predetermined period. The difference data obtained by the arithmetic means is added or subtracted to the output time code data, and the addition or subtraction result is used as time code data at a position where the time code signal is reproduced. When it is determined that there is no continuity of the time code data, the difference data is added or subtracted to the time code data read before the period corresponding to the predetermined period, and the result of the addition or subtraction is determined by the determination unit. And the time code data at the position where the time code signal is reproduced until it is determined that the time code data has continuity. Playback device.