JPH0120588B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to television special effects waveform generators, and more particularly to techniques for varying the aspect ratio of waveforms.

In general, this type of special effect waveform generator is used when switching between two television video signals, using the special effect waveform generated corresponding to the fader as a key signal when switching from one video signal to the other video signal. It is used in

Conventional special effect waveform generators change the aspect ratio of the special effect waveform by changing the mixing ratio of fundamental waves of horizontal and vertical periods. FIG. 1 is a block diagram of a conventional special effects waveform generator, in which 1 is a horizontal periodic fundamental wave generation circuit, 2 is a vertical periodic fundamental wave generation circuit, 3 and 4 are multiplication circuits, and 6
is an adder circuit, and 7 is a waveform shaping circuit. From these horizontal and vertical period fundamental wave generation circuits 1 and 2,
Assume that triangular waves H and V as shown in FIG. 2 are generated. Note that here, a triangular wave with equal horizontal and vertical periods is used.

When these triangular waves H and V and aspect coefficients φ ₁ and φ ₂ are multiplied by the first and second multiplier circuits 3 and 4 and the outputs are added by the adder circuit 6, the following equation is obtained as an output.

φ ₁ ·H + φ ₂ ·V=A (1) These aspect coefficients φ ₁ and φ ₂ have no fixed relationship because the operator sets and operates them appropriately while looking at the video screen. So, for example, φ ₁ =
If 1/2, φ ₂ = 2, then from equation (1), 1/2 x H + 2 x V = A, and since H and V take the maximum value +1 and minimum value -1 from Figure 2, the maximum value of A, The minimum value is +
2.5, −2.5. Similarly, when φ ₁ =1 and φ ₂ =1, the maximum and minimum values of A are +2 and −2.

Therefore, the maximum value and minimum value of the waveform level A will change due to a change in the aspect coefficient. Here, if the fader data moves within a range of ±2, the waveform level A=±2.5, which exceeds the range that the fader data can take, so there is a problem that the effect waveform remains on the screen without being cut off.

FIGS. 3a and 3b are diagrams illustrating this relationship.
The waveform 10, which is a composite of the waveforms H and V, has a conical range between +2.5 and -2.5 as shown in FIG. 3a, and the slice plane 11 moves up and down in accordance with the fader data.
However, since the possible range of the fader data is ±2, the effective screen 12 switched by this fader data is ±2, as shown in FIG. 3b.
Within the range of 2, the other portions remain as portions 13 that cannot be removed due to the fader data without being switched.

The purpose of the present invention is to solve the above-mentioned drawbacks by setting the aspect coefficients in a predetermined relationship to limit the mixing ratio of the fundamental waves of the horizontal and vertical periods, and to make it possible to cut the waveform even if the aspect ratio is changed. The purpose of the present invention is to provide a special effects waveform generator.

The special effect waveform generator of the present invention includes a horizontal fundamental wave generation circuit that generates a fundamental wave with a horizontal period, a horizontal fundamental wave generation circuit that generates a fundamental wave with a vertical period, and an aspect generator that receives aspect data and has a predetermined relationship. an aspect coefficient generation circuit that calculates a coefficient; first and second multiplication circuits that respectively multiply each output of the aspect coefficient generation circuit by each output of the horizontal and vertical fundamental wave generation circuits; and each of these multiplication circuits. and a waveform shaping circuit that compares the output of the adder circuit with fader data and outputs a special effect waveform.

Next, the present invention will be explained in detail with reference to the drawings.

FIG. 4 is a block diagram of an embodiment of the present invention.
The same numbers as in FIG. 1 indicate the same components, and 5 is an aspect coefficient generating circuit. In this embodiment, the output of the horizontal periodic fundamental wave generation circuit 1 is H, the output of the vertical periodic fundamental wave generation circuit 2 is V, and the first and second
The outputs of the aspect coefficient generation circuit 5 which are input to the multiplier circuits 3 and 4 are φ ₁ and φ ₂ respectively, and the adder circuit 6
The function and operation of each component will be explained step by step, using the output as A.

Further, FIG. 5 shows the aspect coefficients φ ₁ ,
This is a graph showing the relationship between φ ₂ and the relationship between these coefficients φ ₁ and φ ₂ calculated from fader data as shown below.

φ ₁ +φ ₂ = 2 ...(2) Note that the aspect coefficient generating circuit 5 only needs to calculate so that the output satisfies equation (2) when arbitrary aspect data is input, so simple multiplication is required. It can be easily configured by providing a circuit and an addition/subtraction circuit.

Here, assuming the relationship of equation (1), for example, φ ₁
When equilevel lines of A=0 are drawn in the case of A=1 and the case of φ ₁ =1/2, a parallelogram as shown in FIG. 6 is obtained. In this figure, the dotted line portion is the waveform outside the effective screen. A special effect waveform is obtained by comparing the output of the adder circuit 6 with fader data in the waveform shaping circuit 7. It can be seen that by changing the aspect data in this way, the aspect ratio of the waveform changes. Further, from the relationship in equation (1), even if the aspect data is changed, the maximum and minimum values of A remain constant (±2), so it is possible to cut out the waveform by operating the fader.

FIGS. 7a and 7b show this waveform relationship and correspond to FIGS. 3a and 3b. That is, the waveform 10', which is a composite of the waveforms H and V, is in a conical range of +2 to -2 as shown in FIG. Since also ranges from +2 to -2, the effective screen 1 is switched as shown in FIG. 7b.
2 is included in the range of the fader data.

Note that although two multiplication circuits, the first and second multiplication circuits, are used in this embodiment, it is possible to obtain the same effect with one multiplication circuit by multiplexing data.

As explained above, the present invention allows the aspect ratio to be changed and the waveform to be cropped by multiplying the fundamental wave of the horizontal and vertical periods by an aspect coefficient having a specific relationship. There is an effect.

[Brief explanation of drawings]

Figure 1 is a block diagram of a conventional special effect waveform generator, Figure 2 is an output waveform diagram of the horizontal and vertical periodic fundamental wave generation circuit of Figure 1, and Figures 3a and b are composites with the fader data in Figure 1. 4 is a block diagram of an embodiment of the present invention; FIG. 5 is a graph showing the output relationship of the aspect coefficient generating circuit of FIG. 4; and FIG. Special effect waveform diagram showing the equal level line of A=0 when the aspect coefficient φ ₁ is 1.1/2, Figure 7 a, b
4 is a diagram illustrating the relationship between the fader data, the composite waveform, and the effective screen in FIG. 4. FIG. In the figure: 1...Horizontal periodic fundamental wave generation circuit, 2...Vertical periodic fundamental wave generation circuit, 3, 4...Multiplication circuit, 5...Aspect coefficient generation circuit, 6...Addition circuit, 7...Waveform shaping circuit, 10, 10'... Composite waveform, 11...slice surface,
12... Valid screen, 13... Part that cannot be removed.

Claims (1)

[Claims] 1. A horizontal fundamental wave generation circuit that generates a fundamental wave with a horizontal period, a vertical fundamental wave generation circuit that generates a fundamental wave with a vertical period, and an aspect coefficient generator that receives aspect data and calculates two aspect coefficients whose sum is constant. a first and second circuit for multiplying each output coefficient of the aspect coefficient generation circuit by each output of the horizontal and vertical fundamental wave generation circuits, respectively;
A special effect waveform generator including a multiplier circuit, an adder circuit that adds the outputs of these multiplier circuits, and a waveform shaping circuit that compares the output of the adder circuit with fader data and outputs a special effect waveform.