JPH0296995A - Time code converter - Google Patents

Abstract

PURPOSE:To eliminate errors produced when time codes are inversely converted by outputting phase difference information in addition to converted time codes at the time of converting the time codes. CONSTITUTION:Inputted 1st time codes are read by a CPU 13 at the timing synchronizing to the 2nd reference frame signal through an input interface 15 together with the phase information detected by a phase information detector 14. The CPU 13 converts the read time codes and phase information into 2nd time codes and phase difference information by referring to a time code conversion table 11 and phase information conversion table 12 and outputs the 2nd time codes and phase difference information respectively through the 1st and 2nd output interfaces 16 and 17. Therefore, a time code converter which does not occur any error at the time of time code conversion and is small in hardware scale can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to time code conversion, which is used, for example, when synchronizing a rotary head type digital audio tape recorder (hereinafter referred to as R-DAT) and a VTR for recording and playback. It is related to vessels.

BACKGROUND OF THE INVENTION In recent years, in response to the increasing image quality of VTRs, there has been an increasing demand for audio tape recorders with higher sound quality. R-DAT can be considered as a high-quality recording device to replace conventional analog recording, but for broadcasting purposes, the problem is synchronous recording and synchronous playback of video and audio.

Conventionally, in synchronized operation of VTRs, a time code was recorded simultaneously to specify the address on the tape, and 2
A method is used in which the time codes of the VTRs are compared and the tape running of the VTRs is controlled so that the time codes match. In order to do the same thing when the VTR and R-DAT are running in sync, a time code converter is needed to convert one time code to the other, since the time code frame periods of the VTR and R-DAT are different. is necessary.

An example of the above-mentioned conventional time code converter will be described below with reference to the drawings.

FIG. 5 is a diagram showing input and output of a conventional time code converter. In FIG. 5, 51 is a time code converter, which converts the time code of the first frame period (hereinafter referred to as the first time code) and the reference signal of the first frame period (hereinafter referred to as the first frame reference signal). ) and a reference signal with a second frame period (hereinafter referred to as a second frame reference signal) are input, and are converted into a time code with a second frame period (hereinafter referred to as a second time code) and output.

FIG. 6 is a timing chart showing the operation of the time code converter. In FIG. 6, (A) is the first time code, (B) is the first frame reference signal, (C
) represents the second frame reference signal, (D) represents the second time code, and (E) represents the operation timing of the first tom code obtained by inversely converting the second time code. In FIG. 6, the second time code is shown surrounded by mouths to distinguish it from the first time code. In Figure 6, Pl
(+ is an integer) is the time from the start point of the first frame reference signal to the start point of the second frame reference signal, and is called phase information. In FIG. 6, the first frame period is longer than the second frame period JtJI, so
For example, when the first time code is 2 frames, there are two pieces of phase information, Pl and P2'' (the latter phase information is given a suffix to distinguish between the two).

The time code conversion is performed by matching the starting point of 0:00:00:00 seconds and 0 frame of the second time code on the first time code, thereby converting the first time code into an associated time code. If the first frame period is longer than the second frame period as shown in FIG. 6, the first time code alone cannot be uniquely converted into the second time code. Therefore, the first time code and the phase information of the first frame reference signal and the second frame reference signal are used to convert to the second time code. for example,
When the O frame and PO of the first time code are input, they are converted to the O frame of the second time code, and the first time code -1! When 1 frame and PI are input, it is converted to 2 frames of the second time code, and when 2 frames of the first time code and PI are input, it is converted to 2 frames of the second time code, and Time code conversion is performed in such a way that when two frames of the first time code and P2' are input, they are converted to the third frame of the second time code. FIG. 7 shows the configuration of a conventional time code converter. In FIG. 7, 71 is a time code conversion table, 72 is a central processing unit (hereinafter referred to as CPU), and 73 is phase information detection for detecting phase information of the first frame reference signal and the second frame reference signal. vessel,
74 is an input interface for inputting the first time code, 75 is an output interface for outputting the second time code, and 76 is a bus for address and data.

Regarding the time code converter configured as above,
The operation will be explained below.

The first time code read by a time code reader (not shown) at a timing synchronized with the first frame reference signal is read into the CPU 72 via the input interface 74 at a timing synchronized with the second frame reference signal. It will be done. At the same time, the phase information detected by the phase information detector 73 is also read into the CPU 72. The CPU 72 converts the read first time code and phase information into a second time code by referring to the time code conversion table 71, and outputs the first time code to the output interface 7.
5, the second time code is generated by a time code generator (
(not shown).

Problems to be Solved by the Invention However, in the conventional time code converter as described above, in order to accurately return the time code obtained by time code conversion to the original time code by time code inverse conversion, it is necessary to perform time code conversion. At the time and inverse transformation, the first
The timings of the first frame reference signal and the second frame reference signal had to match. Therefore, if these conditions are not satisfied, for example, the second time code obtained by converting the first time code is recorded, the second time code is played back later, and the time code is reversely converted. When the original first time code is reproduced by doing so, there is a problem in that an error occurs during time code inverse conversion. The operation will be explained using FIG. In Figure 6, (A) is the first time code, (D) is (A) and phase information P1.
The second time code obtained from (E) is the first time code obtained by inversely converting the second time code of (D). At the time of time code inverse conversion, it is assumed that there is no information that defines the phase relationship between the first time code and the second time code. Since there is no information that specifies the phase relationship, when inverting timecodes, the corresponding timecodes are created by matching the starting points of the 0:00:00:00 frame of the first timecode and the second timecode. Convert inversely. Comparing the first time code in (A) and the first time code obtained by time code inverse conversion in (E), the time of phase information PO of O hours, O minutes, O seconds, and 0 frames between them. It can be seen that an error occurs.

Further, in the conventional time code converter as described above, the size of the time code conversion table becomes extremely large, so that the time code converter has a problem that the /)-ware scale of the time code converter is large.

For example, the SMPTE time code (frame period = 1001÷3o = 33.3
7m5) to the R-DAT running time (frame period = 30 mS), a time code conversion table for 24 hours is required for each R-DAT frame. That is, 24X60X60X100÷3=2.
A time code conversion table for 88x10e frames is required. If hours, minutes, seconds, and frames are each expressed in two digits, ie, one byte, in BCD format, four bytes are required for one frame. Therefore 1, 152X
A 107-byte time code conversion table is required.

In view of the above problems, the present invention eliminates errors during time code inverse conversion by outputting phase difference information during time code conversion, and reduces the hardware scale by reducing the size of the conversion table. It provides a time code converter.

Means for Solving the Problems In order to solve the above problems, the time code converter of the present invention includes a time code conversion table of the least common multiple of the first frame period and the second frame period;
and a phase information detector that detects phase information of a reference signal of the first frame period and a reference signal of the second frame period, and has the first frame period. Conversion of converting a time code and phase information detected by the phase information detector into a time code and phase difference information having the second frame period using the time food conversion table and the phase information conversion table. The device is configured to have means.

Effect The present invention eliminates errors during time code inverse conversion by outputting phase difference information during time code conversion.
By adopting a configuration that utilizes the periodicity between time codes having two different frame periods, it is possible to realize a time code converter with a small conversion table size and small hardware scale.

Example Below, regarding a time code converter according to an example of the present invention,
Please refer to the drawings for explanation.

FIG. 3 is a diagram showing input and output of a time code converter according to an embodiment of the present invention. In FIG. 3, 31 is a time code converter, which inputs a first time code, a first frame reference signal, and a second frame reference signal, and converts a second time code into a second frame reference signal.
Convert to time code and phase difference information and output. The difference between the time code converter of this embodiment and the conventional time code converter shown in FIG. 5 is that this embodiment outputs phase difference information.

The phase difference information is based on the phase information representing the time from the frame start point of the first time code to the frame start point of the second time code. It is obtained by subtracting the phase information (hereinafter referred to as reference phase information) when the starting points of the hour 0 minute 0 second O frame are matched.

FIG. 4 is a timing chart showing the operation of the time code converter of this embodiment. In Figure 4, (A)
is the first time code, (,B) is 0:00:00:00:00
The second time code (hereinafter referred to as the second reference time code), which is the reference when the start point of the frame is made to match the first time code, (C) and (D) are the times of this embodiment, respectively. The second time code and phase difference information 1u obtained by the code converter, (E) is the first time code obtained by inverse time code conversion from the second time code of (C) and the phase difference information of (D). It represents the operating timing of the time code. The operation of converting the first time code in (A) into the second time code in (C) is the same as in the conventional example, and the explanation will be omitted. This embodiment differs from the conventional example in that, at the time of time code conversion, the converted second time code (C) is obtained at the same time as the phase difference information (D).

Phase difference information a refers to phase information PI to reference phase information Q+
For example, as shown in Figure 4, (
If the first timecode of A) is 5 frames, then a=P
It is determined by 5-Q5. The phase difference information can also be interpreted as the phase difference between the second time code in (C) and the second Motosan time code in (B) obtained by time code conversion, and therefore, as shown in FIG. When the time code changes continuously as shown in (D), the phase difference information in (D) has a constant value a. When converting timecode inversely, (C)
By considering the phase difference information in (D) in addition to the second time code in (E), the original first time code is exactly as shown in (E)
timecode.

As described above, according to this embodiment, by outputting phase difference information in addition to the time code converted during time code conversion, errors during time code inverse conversion can be eliminated.

FIG. 1 shows the configuration of a time code converter according to an embodiment of the present invention. In FIG. 1, 1■ is a time code conversion table, 12 is a phase information conversion table, 13 is a central processing unit (CPU), and 14 is for detecting phase information of the first frame reference signal and the second frame reference signal. 15 is an input interface for inputting the first time code, 16 is a first output interface for outputting the second time code,
17 is a second output interface for outputting phase difference information, and 18 is a bus for address and data.

Regarding the time code converter configured as above,
The operation will be explained below. The input first time code is read into the CPU 13 via the input interface 15 at a timing synchronized with the second frame reference signal. The phase information detected by the phase information detector 14 is also CP
It is read into U13 at the same time. The CPU 13 converts a time code conversion table 11 and a phase information conversion table 12 from the read first time code and the phase information.
By referring to the information, the second time code and phase difference information are converted into a second time code and phase difference information, and output via the first output interface 16 and the second output interface 17, respectively.

The differences between this embodiment and the conventional example shown in FIG. 7 are the size of the time code conversion table, the provision of a phase information conversion table for outputting phase difference information, and the fact that the time code conversion table and This is time code conversion processing using the phase information conversion table. These points will be explained in detail below.

Regarding the time code conversion table, in the conventional example, there are 24
Whereas a table for time is required, in this embodiment, a table for time that is the least common multiple of the first frame period and the second frame period may be used.

Therefore, when using the NTSC color one-way SMPTE time code and the R-DAT running time as the first and second time codes, respectively, as in the conventional example, in this embodiment, the R-DAT frame unit is 100
One frame is enough.

This is 1/2877th of the conventional table size.

Hereinafter, regarding the time code conversion processing procedure using the time code conversion table and the phase information conversion table, the first and second time codes will be converted to NTSC, color, and SMPTE time codes, respectively. Refer to the drawing for an example of using R-DAT's running time. I will explain using IC4L/.

FIG. 2 is a flowchart showing time code conversion processing in an embodiment of the present invention.

(Process 1) Find the total number of time hood frames in the first frame period. If the hour, minute, second, and frame of the SMPTE time code are H, M, and 31F, respectively, then O:0:0:0
Total number of frames from 0 frames per second (OIII
The total number of frames (0 minutes, 0 seconds) corresponding to the time elapsed from 0 frames) is given by equation (1).

N=1800X60XH+1800XM+30XS+F
...-... (1) In the case of drop frame, the value for the correction frame from N in equation (1) (2XM-2X INT (M÷10) + 10
8XH) Let the subtracted value be N. INT() represents a function that truncates the decimal part in () and converts it into an integer.

(Process 2) Divide the total number of frames of the time code of the first frame period by the number of frames of the time code of the first frame period, which corresponds to the time that is the least common multiple of the first frame period and the second frame period. Find the quotient and remainder. Since SMPTE time code 900 frames and R-DAT 1001 frames match, the quotient I and the remainder are (2).
It is given by Equation (3).

K=INT(N÷900) ・・・・・・(
2) L=N-KX900...
- (3) and (Processing 3) The converted time code and phase difference information of the second frame period are obtained by referring to the time code conversion table and the phase information conversion table from the remainder and the phase information detected by the phase information detector. and seek. The time code conversion table is R
- There are 1001 frames in units of DAT frames, and as the remainder increases, the value of the converted time code M increases by 1 from O until it reaches 1000. The phase information conversion table has 1001 frames in units of R-DAT frames, and stores reference phase information. The phase difference information a is the phase information pt, jJu,
Letting It phase information be Q, it is given by equation (4).

a=P-Q...
(4) When the value of a is negative, subtract 1 from the converted time code M and add the time of one frame of R-DAT to a to make the value of a positive. Furthermore, when the value of a is greater than the time of one frame of R-DAT, 1 is added to the conversion time code M and the time of one frame of R-DAT is subtracted from a.

(Processing 4) From the time code of the second frame period to the second
Find the total number of time code frames in the frame period. If the total number of frames of R-DAT is Nd, Nd is (
5) Given by Eq.

Nd=1001XK+M ・・・・・・(
5) (Process 5) Find the time code of the second frame period from the total number of frames of the time code of the second frame period. R-DA
If the hours, minutes, seconds, and frames of the running time of T are Hdl Ma, Sa, and Fd, respectively, then Hdl Md1
Sd and Fd are expressed by equations (6), (7), and (8), respectively.
) is given by equation (9).

Hd = INT (Nd ÷2000÷60
)... (6) Zl = Nd -2000X60
XHdMa=INT(Zl ÷2000)
... (7) Z2 = ZI -2000XMd Sd' = 3XINT (Z2 ÷ 100) Z3
:Z2 -100XSd'÷3Sd=Sd''+I
NT (Z3 ÷33) ... (8) Fd
=Z3 -53XINT (Z3 ÷33) However, Sa゛, Zl, Z2, and Z3 are variables for work.

As described above, the time code and phase information detector having the first frame period includes a time code conversion table and a phase information conversion table for a time that is the least common multiple of the first frame period and the second frame period. The time code is reversed by converting the detected phase information into a time code having the second frame period and phase difference information using the time code conversion table and the phase information conversion table, and outputting the time code and phase difference information. It is possible to provide a time code converter that does not generate errors during conversion and has small hardware scale.

Effects of the Invention As described above, the present invention provides a time code conversion table for a time that is the least common multiple of a first frame period and a second frame period, a phase information conversion table for said time, and a time code conversion table for said time
a phase information detector that detects phase information of a reference signal having a frame period of , and a reference signal having a second frame period; information, by using the time code conversion table and the phase information conversion table, and converting means to convert the time code having the second frame period into phase difference information. There is no error during code inversion,
A time code converter with small hardware scale can be realized.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a time code converter according to an embodiment of the present invention, FIG. 2 is a flowchart showing time code conversion processing according to the embodiment, and FIG. 3 is an input diagram of a time code converter according to the embodiment. FIG. 4 is a timing chart showing the operation of the time code converter of the same embodiment.
Figure 5 is a diagram showing the input and output of a conventional time code converter.
FIG. 6 is a timing chart showing the operation of a conventional time code converter, and FIG. 7 is a block diagram of the conventional time code converter. 11... Time code conversion table, 12...
Phase information conversion table, 13... Central processing unit, 14... Phase information detector, 15... Input interface, 16... First output interface, 17... Second output interface,
18...Bus, 31...Time code converter. Name of agent: Patent attorney Shigeko Kurino and one other person Figure i

Claims (2)

[Claims] (1) A time code conversion table for the least common multiple of the first frame period and the second frame period, a phase information conversion table for the time, a reference signal for the first frame period, and the second frame. a phase information detector that detects phase information of a reference signal of a period, and converts the time code conversion table and the phase from the time code having the first frame period and the phase information detected by the phase information detector. Using the information conversion table, the second
What is claimed is: 1. A time code converter comprising: a time code having a frame period of (2) The converting means includes means for determining the total number of frames of the time code in the first frame period, and converting the total number of frames of the time code in the first frame period into the first frame period and the second frame period. means for dividing by the number of frames of the time code of the first frame period corresponding to the least common multiple of the time and calculating the quotient and remainder; and a time code conversion table from the remainder and the phase information detected by the phase information detector. means for determining the converted time code and phase difference information of the second frame period by referring to a phase information conversion table; and means for determining the converted time code of the second frame period from the quotient and the converted time code of the second frame period Claims characterized by comprising means for determining the total number of frames of the time code of the period, and means for determining the time code of the second frame period from the total number of frames of the time code of the second frame period. A time code converter according to scope 1.