JPH065897B2 - Field identification circuit for video equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention generates unique data relating to fields of a video signal, and distinguishes odd and even fields of a television signal, distinguishes the number of scanning lines, interlaces, The present invention relates to a field identification circuit of a video device for performing field identification such as non-interlace identification.

[Prior art]

As a circuit for identifying a field of a television signal, a field identifying circuit as shown in FIG. 5 has been conventionally proposed. FIG. 4 shows a time relationship between a sync signal in a video signal, a vertical sync signal (hereinafter abbreviated as VD) and a horizontal sync signal (hereinafter abbreviated as HD) that have been synchronously separated.
FIG. 4A shows an odd field, and FIG. 4B shows an even field.

In FIG. 5, reference numeral 31 is a flip-flop (hereinafter referred to as FF) in which the output of the output terminal Q is inverted by the rising of the T terminal only when the terminal is "H" and the J terminal and the K terminal are "H", and 32 is the terminal. To "L", output terminal Q
"H" is output to, and when the terminal is "H", the output of the output terminal Q is inverted by the rising of the T terminal. FF
A counter 33 counts the input from the T terminal and outputs the count data to the output terminals Q _{1 to} Q ₄ .

Next, the operation will be described. As shown in FIGS. 4 (a) and 4 (b), the time from the leading edge of VD to the leading edge of HD is different, such as T1 in the odd field and T2 in the even field. At this time, field identification is performed by measuring the times T1 and T2.

When VD becomes "H", FF31 and counter 33
Is released, the output terminal Q of the FF 31 is inverted by the reference clock and is output to the counter 33, and the counting of the counter 33 is started. After that, the output H of 32 is inverted by the rise of HD, and the output from the FF 31 is stopped. Then, the counter 33 stops counting and the data is fixed. Odd / even fields may be determined using this data.

[Problems to be solved by the invention]

Since the field identification device of the conventional video equipment is configured as described above, in addition to the need for the reference clock, when the horizontal frequency changes, the reference clock must be changed or the judgment criterion must be changed. Therefore, it can be used only for a specific frequency. There is also a problem that the number of scanning lines cannot be automatically determined.

The present invention has been made to solve such a problem, and it is possible to identify a field without a reference clock, and even if the number of horizontal scanning lines changes, the change in the number of horizontal scanning lines is automatically determined to identify the field. At the same time, the change data of the number of horizontal scanning lines indicating the number of horizontal scanning lines in the current field of the horizontal scanning signal, that is, the number of horizontal scanning lines at the rising timing of the vertical synchronizing signal is set to 0. It is an object of the present invention to obtain a field identification circuit of a video device which can automatically determine interlace and non-interlace.

[Means for solving problems]

The field discriminating circuit of the video equipment according to the present invention comprises means for counting horizontal synchronizing signals between vertical synchronizing signals of consecutive fields, compares the count values between different fields by the counting means, and determines the relative relationship between them. Depending on whether it is interlaced or non-interlaced, or whether the current field is an odd field or an even field, the number of scanning lines is cleared by the vertical sync signal, and by counting according to the horizontal sync signal. A means for indicating the number of horizontal scanning line counted from the rising edge of the vertical synchronizing signal in the field currently being scanned is provided.

[Action]

According to the present invention, the horizontal synchronization number of each field is determined by measuring the horizontal synchronization signal with the vertical synchronization signal as a reference, and the horizontal frequency changes in the field identification, the interlace / non-interlace discrimination, and the scanning line number discrimination. It can also be done.

〔Example〕

An embodiment of a field identification circuit of a video device according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the embodiment. In FIG. 1, a sync separation circuit 1 performs a sync separation of a video signal, and its outputs, that is, HD and VD are input to an input circuit 2 of a microcomputer 6.

The microcomputer 6 includes an input circuit 2, a memory 3 and a CP.
A U4 and an output circuit 5, and a CPU 4 sends and receives data to and from the input circuit 2, the memory 3, and the output circuit 4, respectively. It outputs data and interlaced / non-interlaced judgment data.

Next, the operation of this embodiment will be described with reference to FIGS. In this embodiment, the one having a large number of horizontal synchronizing signals between the vertical synchronizing signals is an odd field and the one having a smaller number of horizontal synchronizing signals is an even field. FIG. 2 is a flow chart showing the field identification program stored in the memory 3 of the microcomputer 6, and FIG. 3 is an explanatory diagram of the relationship between HD and VD in the odd / even field of the video signal.

First, when the video signal is input to the sync separation circuit 1, FIG.
As shown in (a) to FIG. 3 (d), HD and VD are generated by synchronous separation. The generated HD and VD are input from the input circuit 2 to the CPU 4 of the microcomputer 6, and then the field identification operation, the scanning line number output operation, the interlace / non-interlace determination including the steps 7 to 30 in FIG. The operation is started.

In these operations, the rising portion of the input VD is determined in step 7, and the count value n _{1 of the} number of scanning lines in the first field and the count value n ₂ of the next field are set to 0 in steps 8 and 9. . Then, it is judged in step 10 that HD is input, and if it is input, the number n ₁ of scanning lines in the first field is incremented by ₁ in step 11, and whether the rising edge of the pair of VDs is input or not is input in step 12. Judge, and if not input, wait for HD input again.

If VD is input in step 12, it is determined as the next field, and the same method as in the first field is used,
The number of scanning lines n ₂ of the next field is obtained through 3 and 14.

In step 16, it is judged whether the data of the count value n ₁ of the first field and the count value n ₂ of the next field thus obtained are the same, and if they are the same, it is determined that the data is non-interlaced. The data indicating that there is is output from the output circuit 5 in step 17.

If they are not the same, interlace is assumed, and n ₁
> N ₂ or in step 18. If n ₁ > n _2, the count value n _{2 with} the smaller number of scanning lines is set as the even field, and the data is transferred to the even field count value n ₄ in step 19.

When n ₁ > n ₂ is not satisfied, the count value n ₁ is the even field count value, and therefore the count value n ₄ is moved to step 20.

Then, VD is determined in step 21, the scanning line number count value n ₃ of the current field is cleared to 0 in step 22, and the count value n ₃ is set in step 2 every time HD is input.
The value is incremented by 1 in 4, and the value is output from the output circuit 5 in step 25. That is, the number of horizontal scanning lines currently counted from the rising edge of the vertical synchronizing signal is transmitted to the user as data every moment. This is within the timing of the vertical blanking period (see Fig. 4b) in video equipment.
It may be convenient because it does not appear on the display screen when signals are switched or data is exchanged. Therefore, it is important to know what the horizontal scanning line is from the rising timing of the vertical synchronizing signal VD pulse. Becomes
For this reason, the data of step 25 is set to the next step 27, 2
It is effective data as well as the intermediate data of 9. Then, the operations of the previous steps 23, 24 and 25 are performed until the next rise of VD is determined in step 26.

When VD is input, the number of scan lines in the current field n ₃
If the answer obtained by subtracting the scanning line number n ₄ of the even field from step 27 is 0, the current field is the even field, and therefore the even field data is output from the output circuit 5 in step 28.

If the answer is not 0, is the answer 1?
Judge at 9. If it is 1, it is an odd field, so
In step 30, the odd field data is output. If the answer is not 1, it is determined that the field is neither an even field nor an odd field, and the process returns to step 7 to measure the number of horizontal scanning lines again.

In the above embodiment, of the two consecutive fields,
If the field having a large number of scanning lines is an odd field, but the field having a large number of scanning lines is an even field, the odd field data is output in step 28 and the even field data is output in step 30. become. Further, although the above-mentioned embodiment is a software processing using a microcomputer, it is also possible to configure it by a digital circuit to realize all hardware. The concept of the circuit configuration in this case is the same as that of software.

〔The invention's effect〕

As described above, the present invention counts horizontal synchronizing signals between vertical synchronizing signals of two consecutive fields, compares the count values between the fields, and discriminates whether an odd field or an even field, interlaced or non-interlaced. In addition to identifying whether or not the predetermined timing based on the vertical synchronization signal, for example, the information that is the basis for determining whether it is within the vertical blanking period is output.
It is possible to identify fields corresponding to all frequencies without using a reference clock, and to automatically identify interlace and non-interlace, and automatically determine the number of horizontal scanning lines. There is also an effect of facilitating the signal processing of switching the video signal at the switching timing of the signal, for example, the timing at which the character information (FIG. 4A) is avoided while switching during the vertical blanking period. .

[Brief description of drawings]

FIG. 1 is a block diagram showing the overall configuration of an embodiment of a field identification circuit of a video device according to the present invention, FIG. 2 is a flow chart showing the operation of the field identification circuit of the same video device, and FIG. 4 is an input signal relationship diagram for explaining the operation of the field identification circuit, FIG. 4 is an input signal relationship diagram for explaining the operation of the conventional video equipment, and FIG. 5 is a block diagram of the field identification circuit of the conventional video equipment. is there. 1 ... Sync separation circuit, 2 ... Input circuit, 3 ... Memory, 4 ... C
PU, 5 ... Output circuit, 6 ... Microcomputer.

Claims (1)

[Claims] 1. A horizontal sync signal and a vertical sync signal are separated from a video signal and output, and unique data relating to a field of the video signal is generated based on the horizontal sync signal and the vertical sync signal to identify the field. In the interlaced circuit, it is determined whether the count means for counting the horizontal synchronizing signals between the vertical synchronizing signals of two consecutive fields is equal to the count value between the different fields by the counting means. Means for discriminating between non-interlace and non-interlace, a means for discriminating the magnitude relation between the respective count values to discriminate whether it is an odd field or an even field, and a count of the number of scanning lines corresponding to the vertical synchronizing signal. And a field of a video device including means for outputting a counted value in response to the input of the horizontal synchronizing signal. Identification circuit.