JPH03249882A - Digital video switching device - Google Patents

Abstract

PURPOSE:To decrease the number of input format converting circuits in accordance therewith even when the number of inputs of a video signal is smaller than the number of a video signal to be synthesized by providing the input format converting circuit for converting a pedestal level in front of a video switching circuit. CONSTITUTION:Digital video signal inputs inputted to input format converting circuits 1-1 to 1-M are supplied to an M-input 2N-output video switching circuit 2 by setting a pedestal level to a zero level, and by executing the format conversion and switching the video signal, 2N pieces of digital video signals are outputted. Subsequently, two pieces each are supplied successively to video mixing and amplifying circuits 3-1 to 3-N, and by setting the pedestal level to zero, gain control is executed and the signals are synthesized, a pedestal level is reproduced by output format converting circuits 4-1 to 4-N, and a first- an N-th digital video signals are outputted. In such a way, even in the case the number M of inputs of the video signal is smaller than the number 2N of the video signals to be synthesized, the number of format converting circuits 1-1 to 1-M can be decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a digital video switching device, and more particularly to a digital video switching device for switching digitized television video signals.

[Conventional technology]

Digital video switching devices that switch digitized television video signals are well known.

Conventionally, this type of digital video switching device has an M input 2N output video switching circuit that receives M first to M digital video signal inputs, as shown in FIG. Outputs 2N video signals, these outputs are 2N
format conversion circuit 5-1.5-2. ... 2N-1 format conversion circuit 5- (2N-1),
5-2N. The 2N video signals are sent to N first video mixing amplification circuits 3-1 to 3- in groups of two.
For this synthesis, the first format conversion circuits 5-1 each have a set of two format conversion circuits that convert the pedestal level of the video signal to zero level.
．． This is performed by the second format conversion circuit 5-2 to the 2N-1 format conversion circuit 5-(2N-1) and the 2N-th format conversion circuit 5-2N. N first video mixing amplification circuits 3 after video mixing and synthesis
-1 to N-th video mixing amplification circuits 3-N respectively output from N first output format conversion circuits 4-1 to N-th video mixing amplification circuits 3-N.
The signals are supplied to the output format conversion circuit 4-N, where they are reproduced at a pedestal level and output as first to Nth digital video signal outputs, respectively.

[Problem to be solved by the invention]

The conventional digital video switching device described above uses a format conversion circuit that converts the pedestal level for combining when the number M of video signal inputs is smaller than the number 2N of video signals output from the video switching circuit and to be combined. The disadvantage is that the number of .

[Means to solve the problem]

The digital video switching Ml of the present invention is a digitized M
M input format conversion circuits that receive input video signals and convert the pedestal level to zero; and M input 2N input format conversion circuits that receive outputs from the M input format conversion circuits and output 2N digital video signals. An output video switching circuit and 2 outputs from the M input 2N output video switching circuit.
N video mixing amplification circuits that sequentially receive N digital video signals two by two and synthesize and output the composite including a predetermined effect; and the M input formats for the outputs of the N video mixing amplification circuits. It is configured to include N output format conversion circuits that reproduce the pedestal level lost in the conversion circuit and send out N digital video signal outputs.

〔Example〕

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

FIG. 1 is a diagram illustrating an example of a practical example of prohibiting digital video switching according to the present invention. The embodiment shown in FIG. 1 includes M first input format conversion circuits 1-1 to M-th input format conversion circuits 1-M, M input 2N output video switching circuits 2. N first video mixing amplification circuits 3-1 to Nth video mixing amplification circuits 3-N.

It is configured to include N first output format conversion circuits 3-1 to N-th output format conversion circuits 4-N.

Next, the operation of the embodiment shown in FIG. 1 will be explained.

The first to M-th digital video signal inputs input to the M first input format conversion circuits 1-1 to M-th input format conversion circuits 1-M are M input 2N outputs with the pedestal level as zero level. The signal is supplied to the video switching circuit 2. The M-input 2N-output video switching circuit 2 converts the format of the video signal and switches the video signal to zero pedestal level, and outputs 2N digital video signals. These 2N
The digital video signals are sequentially transmitted two by two to N first video mixing amplification circuits 3-1 to Nth video mixing amplification circuits 3-N.
is supplied to Two digital video signals are synthesized by these video mixing amplification circuits under gain control with the pedestal level set to zero. Since this composite output still has a pedestal level of zero, for example, the first output format conversion circuit 4-1 reproduces the pedestal level,
Converting to the same format as the input. Similar operations are performed in other video mixing amplification circuits and output format conversion circuits. A first digital video signal output to an Nth digital video signal output are obtained.

In this way, digital video can be switched by making the number M of digital video signal inputs correspond to the output format conversion circuit.

〔Effect of the invention〕

As explained above, in the present invention, the number M of input video signals is smaller than the number 2N of video signals to be combined by arranging the input format conversion circuit for pedestal level conversion before the video switching circuit. Even when the present invention is used, there is an effect that the number of input format conversion circuits can be correspondingly reduced.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the actual flow side of a digital video switching GM of the present invention, and FIG. 2 is a block diagram of a conventional digital video switching M. 1-1 to 1-M...first input format conversion circuit to M-th input format conversion circuit, 2...
・・M input 2N output video switching circuit, 3-1 to 3-N・・
. . . 1st video mixing amplifier circuit to Nth video mixing amplifier circuit, 4-1 to 4-N . . . 1st output format conversion circuit to Nth output format conversion circuit, 5-
1 to 5-2N...first format conversion circuit to second format conversion circuit.

Claims (1)

[Claims] M input format conversion circuits that receive M digitized video signal inputs and convert the pedestal level to zero, and receive outputs from the M input format conversion circuits to convert 2N digital video signals. an M-input 2N-output video switching circuit that outputs, and N video mixing amplification that sequentially receives two 2N digital video signals outputted from the M-input 2N-output video switching circuit and synthesizes them with a predetermined effect. circuit, and N output format conversions for regenerating the pedestal level lost in the M input format conversion circuits for the outputs of the N video mixing amplification circuits and sending out N digital video signal outputs. A digital video switching device comprising a circuit.