JPH0120597B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a time code generation device that generates time codes for color video signals that perform color framing in four consecutive frames, such as PAL-M color television signals, and in particular, it can be used without any trouble by simply adding a simple configuration. This allows the use of NTSC time code. As a color video signal that performs color framing in 4 consecutive frames (8 fields),
PAL-M color television signals are known. This PAL-M color television signal has 525 scanning lines and a frame frequency of 29.95 frames/second. In this regard
The PAL-M system differs from the NTSC system. On the other hand, the PAL-M system differs from the NTSC system in that color framing is performed using four consecutive frames as described above. For this reason, it was thought that it would be impossible to use exactly the same time code system between the two. Therefore, for example, in the drop frame formation method, the NTSC method and
Different PAL-M systems have been proposed. That is, in the NTSC system, two drop frames are created every minute except every 10 minutes. On the other hand,
In the PAL-M system, four drop frames are created every two minutes, except every 20 minutes. Even though the frame frequency is the same 29.95 frames/second,
The reason why the drop frames of the NTSC system are set to two frames each and the drop frames of the PAL-M system are set to four frames each is that the playback position on the tape corresponds to which frame in a series of frames for color framing. This is because, in order to be able to determine from the time code whether or not a frame is to be used, a series of frames for color framing must be collectively set as a drop frame. Furthermore, if it is possible to determine from the time code which frame the playback position on the tape corresponds to in a series of frames for color framing during playback, color framing can be easily performed during editing, thereby reducing screen deterioration. It can be prevented. By the way, the PAL-M system is not a color television broadcasting system that is popular in many countries (only in Brazil). Therefore, it is difficult for manufacturers and users to adopt the PAL-M specific time code system and manufacture and use peripheral devices such as editing devices, time code generators, and time code readers that are specific to this system. It becomes a burden. Therefore, considering the similarities between the NTSC and PAL-M systems, we decided to replace the NTSC time code with the PAL-M system.
-It was requested that it be diverted to the M method. In this case, the series of four frames for color framing in the PAL-M system are not deleted all at once as drop frames, but only two frames are used as drop frames. The most important issue is how to determine which of the four frames for color framing the above playback position corresponds to. The present invention was made in view of this point, and is basically used as a time code for a color video signal that performs color framing in four consecutive frames.
Using the NTSC time code, this NTSC
The present invention aims to provide a time code generator capable of determining which of four consecutive frames a playback position on a tape corresponds to based on the time code itself. The time code generator of the present invention will be described below as a PAL-
Figures 1 to 4 show an example of application to the M method.
Let me explain with reference to the diagram. FIG. 1 shows a PAL-M time code generator according to this embodiment. In FIG. 1, a step circuit 1, a preset device 2, a clock generator 3, and a drop frame generation control circuit 4 are used to generate an NTSC time code. That is, the preset device 2 transfers preset data (time code) to the step circuit 1 according to a predetermined operation.
It is to be transferred to. This transfer presets the contents of step circuit 1. clock generator 3
is for controlling the time code of the step circuit 1 in steps. Specifically, when the input to the enable terminal EN of the clock generator 3 is a binary logic signal "1" and a pulse is input to the frame pulse input terminal IN, the step circuit is activated every time this pulse is input. 1
The time code will advance. When in the drop frame mode, the drop frame generation control circuit 4 generates a drop frame in the stepwise circuit 1 according to the drop frame rule of the NTSC system, that is, the rule that two drop frames are generated every minute except every 10 minutes. Control signal
Supply DF. In this case, when the time code being incremented by the step circuit 1 corresponds to a drop frame, the drop frame control signal is
Set the timecode as the next timecode of the drop frame based on DF. The time code formed in this way is
For example, SMPTE (Society of Motion Picture)
and Television Engineers) time code, which represents hours, minutes, seconds, and frames in BCD (binary coded decimal). The correspondence between seconds and frames is 1
Seconds vs. 30 frames. In the following explanation, each digit of the BCD digits constituting this time code is shown in FIG. For example, each digit that makes up the digit that indicates the ones digit of the frame is
Let them be FID8, FID4, FID2, and FID1. The time code thus formed is supplied to the time code modulation circuit 5, and is modulated into, for example, a biphasic signal in this example. Then, the time code signal modulated into a biphasic signal is supplied to a recording device (not shown) via the output terminal 6,
This is recorded on a tape (not shown) together with a PAL-M color television signal. Note that this color television signal is the same as that supplied to the color television signal input terminal 7. Also, the data of some digits of the time code from step circuit 1 can be converted into a time code.
The data is supplied to the frame data conversion circuit 8. This time code/frame data conversion circuit 8 converts the time code into frame data X according to a predetermined rule.
It is converted into . In this case, frame data X is 2-bit data X1, X2,
This is a series of four individual frames encoded to perform PAL-M color framing. The relationship between frame data X and each of the four frames is as shown in Table 1.

[Table] In this example, the rules for converting time code into frame data are shown in Tables 2 and 3. In Tables 2 and 3, each 20-minute period time code corresponds to frame data (first to fourth frames forming color framing). For example, 00:00:00:04 frame,
Frame 05, frame 06, and frame 07 are the first, second, and third frames, respectively, as shown surrounded by broken lines.
This corresponds to the th and 4th frames. Moreover, since there is a certain periodicity between the time code and frame data in Tables 2 and 3, frame data can be easily obtained from the time code. In addition, in Table 2, "0" and "1" with *1 and *2 respectively exist only for 00:00:00.00 frame and 00:00:00.01 frame, and the remaining cases are drop frames. . Furthermore, in Table 3, "0" and "1" marked with *3 and *4 respectively indicate that the frames are not dropped every 10 minutes but are left there.

【table】

[Table] The time code/frame data conversion circuit 8 is combined with the circuit 9 according to the rules shown in Tables 2 and 3.
and an exclusive OR circuit 10. Then, data of the time code [F1D1], [F1D2], [S1D1],
[F10D1], [M1D1], [M10D1], and [DM] are transferred as parallel data, and the logical operation of B=F1D1F1D2F10D1S1D1 {(MID1M10D1)∧DM} is executed here. However, indicates exclusive OR, and ∧ indicates logical product. [DM] is "1" when in drop frame mode, and "0" otherwise. In this case, when the time code corresponds to the first frame or the fourth frame,
B = “0”, and on the other hand, when the time code corresponds to the second or third frame, B
= “1”. For example, at frame 00:00:00:04, [F1D1], [F1D2], [S1D1], [M1D1]
and [M10D1] are respectively “0”, “0”, “0”,
Since they are "0" and "0", B=0. Well,
According to Table 2, this is the first frame. The calculation result B of the combinational circuit 9 is supplied to the first input terminal of the exclusive OR circuit 10.
Also, the second exclusive OR circuit 10
Data [F1D1] of the time code is supplied to the input terminal. In this case, data [F1D1]
The data itself becomes the lower digit data X1 of the frame data X, and the output of the exclusive OR circuit 10 becomes the upper digit data X2 of the frame data X. In other words, if the data [F1D1] is “0”, the time code is the first frame or the third frame.
Corresponding to the th frame, the other data [F1D1]
If is "1", the time code corresponds to the second frame or the fourth frame. This is clear from Tables 2 and 3. This regularity is due to the fact that in the NTSC time code, two frames are combined into a drop frame, so odd corners are not replaced. Therefore, it is clear from Table 1 that [F1D1] and lower digit data X1 of frame data X are equal.
This data [F1D1] is transferred to the comparison circuit 11 as data X1. On the other hand, the output of the exclusive OR circuit 10 is equal to the upper digit data X2 of the frame data X, as shown in Table 4, and is supplied to the comparison circuit 11 as data X2.

[Table] On the other hand, a PAL-M color television signal to be recorded by a recording device or the like is supplied to the synchronization separation circuit 12 via the color television signal input terminal 7. The synchronization separation circuit 12 forms a frame pulse based on the color television signal, and supplies the frame pulse to the frame pulse input terminal IN of the clock generator 3 and the frame data detection circuit 13, respectively. The frame data detection circuit 13 determines the frame data Y of the color television signal to be recorded. That is, frame data detection circuit 1
At step 3, the frame pulse is supplied to the clock input terminal CLOCK of the frequency divider 14 with a frequency division ratio of 1/2.
The output of the frequency divided by the frequency divider 14 is then supplied to the next stage frequency divider 15 with a frequency division ratio of 1/2. Further, reference pulses for color framing are supplied to reset terminals CL of these frequency dividers 14 and 15 via reference pulse input terminals 16, respectively. This reference pulse is a pulse with a period of 4 frames. In this case, the reference pulse, frame pulse, and output pulses of the frequency dividers 14 and 15 are as shown in FIGS. 3A to 3D, respectively. And the frequency divider 14,
The outputs of husband No. 15 are output as lower digit data Y1 and upper digit data Y2 of frame data Y, respectively. Then, the relationship between the frame data Y and each of the series of four frames for color framing is as shown in Table 5, and the frame data Y
is coded in the same way as the frame data X described above.

[Table] The frame data Y thus detected is supplied to the comparison circuit 11, where frame data Y and frame data X are compared. In this case, when frame data X and Y match, the comparison circuit 1
An output of “1” is generated from 1, and when there is a mismatch,
An output of "0" is produced. The output of the comparison circuit 11 is supplied to the enable terminal EN of the clock generator 3. In this case, X=
When the output of the comparison circuit 11 is "1" at Y, the clock generator 3 is driven; on the other hand, when X≠Y and the output is "0", the clock generator 3 is stopped. In such a time code generator, first, the current time is preset into the step circuit 1 by the preset device 2. For example, set this preset value to 00:00:00.
00 frame. Then, [F1D1] is "0" and B is "0". Therefore X
=(0,0). On the other hand, it is assumed that the color television signal from the color television signal input terminal 7 at this time corresponds to the fourth frame. Then Y=
(1, 1). Therefore, in this case, X≠Y, and as a result, the output of the comparison circuit 11 is "0". Therefore, the clock generator 3 is inactive, the step circuit 1 does not step, and its time code does not change even when the next frame pulse arrives. On the other hand, when the color television signal corresponds to the first frame in response to the arrival of the frame pulse, Y=(0,0). Then, X=Y, and the output of the comparison circuit 11 becomes "1". As a result, the clock generator 3 is put into operation, and the contents of the step circuit 1 are thereafter incremented every frame pulse. It will be easily understood that the time code, which is stepped for each frame pulse, is also locked to the frame of the color television signal. Next, a time code reading device for reading the time code generated by the time code generator shown in FIG. 1 will be explained with reference to FIG. 3. Note that in FIG. 3, parts corresponding to those in FIG. 1 are designated by the same reference numerals, and detailed description thereof will be omitted. In FIG. 3, reference numeral 21 indicates a time code signal input terminal, and a biphasic signal reproduced by a reproduction device (not shown) is supplied to a demodulation circuit 22 through this input terminal 21. This demodulation circuit 22 demodulates the biphasic signal and outputs it as parallel data via an output terminal 23. Also, among these parameters, data [F1D1],
[F1D2], [F10D1], [S1D1], [M1D1],
[M10D1] and [DM] are supplied to the time code/frame data conversion circuit 8. When such a reading device reads the time code signal (bi-phase signal) generated by the time code generator shown in FIG. 1, it determines the absolute address of the reproduced color television signal (absolute address of the reproduction position on the tape). Also, based on the frame data In other words, in the time code generation device shown in FIG. Therefore, determining the frame of the time code means determining the frame of the reproduced color television signal. As described above, according to the time code generator of the present invention, the time code of the NTSC system can be determined according to the rules shown in Tables 2 and 3. The generation of time code is controlled so that this frame data matches the frame data of the color television signal to be recorded. Even when performing color framing, the NTSC time code can be used without any problems, reducing the burden on manufacturers and users.In other words, when playing back color television signals, the rules shown in Tables 2 and 3 should be used as keys. Frames of a color television signal can be determined from the time code, and if color framing is performed during editing, etc. based on this, screen deterioration can be prevented.In the above embodiment, the PAL-M system was explained. Other systems can be applied as long as the color video signal is colored in 4 frames.Furthermore, the present invention is not limited to the above-mentioned embodiments, and various configurations may be adopted without departing from the gist of the present invention. Of course you can get it.

[Brief explanation of drawings]

FIG. 1 is a system diagram showing one embodiment of the time code generator of the present invention, and FIGS.
FIG. 4 is a system diagram showing a configuration example of a time code reading device for reading the time code generated in the example of FIG. 1. 1 is a stepping circuit, 3 is a clock generator, 4 is a drop frame generation control circuit, and 8 is a time code/clock generator.
frame data conversion circuit, 11 is a comparison circuit, 13
is a frame data detection circuit.

Claims (1)

[Claims] 1. In a time code generator that generates time codes for PAL-M color video signals that perform color framing on four consecutive frames,
A time code generation circuit that generates the NTSC time code generates the NTSC time code based on the regularity between the NTSC time code and the frame data that displays each of the four consecutive frames. a time code/frame data conversion circuit that converts the frame data into frame data; a frame data detection circuit that detects the frame data of the PAL-M color video signal to be recorded; and a frame data detection circuit that detects the frame data of the PAL-M color video signal to be recorded; a comparison circuit that compares the frame data from the frame data detection circuit, and controls the time code generation circuit based on the comparison result of the comparison circuit, and controls the time code generation circuit to generate an NTSC time code from the time code generation circuit. and the frame data of the PAL-M color video signal have a predetermined regularity.