JPS60163587A - Processing system of video signal - Google Patents

Abstract

PURPOSE:To make it difficult to restore a video signal by nonsubscribers and to prevent unlawful viewing by inverting white and black levels of overall video signals during the specific horizontal scanning period at every horizontal scanning period and conducting scramble processing. CONSTITUTION:A video signal from a video source 11 is added to a video scramble circuit 12 and a burst signal oscillator 13, and a gate 12f of the circuit 12 generates an invertion pulse PIR while a gate pulse GP is being generated from a black/white level invertion control part 12c. The oscillator 13 generates a continuous color burst signal CBS', which is synthesized with the pulse PIR in a synthesizing circuit 14 and transmitted to the receiving side RCV. The received signal is processed by a burst detection circuit 23, a synchronization detection circuit 24, a black/white inversion restoration circuit 25, and inversion identification/inversion drive pulse restoration circuits 26 and 27 at the receiving side RCV. Then the restoration of a video signal by nonsubscribers is made difficult and unlawful viewing can be prevented.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a video signal processing method, in particular, a video signal subjected to scramble processing is transmitted from a transmitter, and only a specific receiver can process the scrambled video signal. The present invention relates to a video signal processing method in a pay television system such as CATV, which restores a processed video signal to a normal original video signal and displays it on a screen.

<Prior art> In pay television systems, normal images can be displayed only on television receivers (referred to as 'ff receivers) owned by subscribers, and normal images can be displayed on TV receivers owned by non-subscribers. The video signal is scrambled on the transmitting side so that it cannot be displayed. That is, in a pay television system, a transmitter suppresses the level of a synchronization signal portion of a video signal (scramble processing), generates a signal to restore the suppressed synchronization signal, and "scrambles the signal". It is transmitted together with the processed video signal. By not providing a synchronization signal restoration function to the TV receivers owned by non-subscribers, the TV receivers are unable to synchronize and normal images are not displayed on the screen. Furthermore, the TV receiver owned by the subscriber is provided with a synchronization signal restoration function so that a normal image is displayed on the screen of the TV receiver.

<Disadvantages of the prior art> However, in the conventional scrambling method, the synchronization signal is uniformly suppressed by a predetermined level. ), it is relatively easy to create a pseudo synchronization signal and display an image on the screen based on the synchronization signal. In other words, the conventional scrambling method may result in illegal reception.

In addition, in the conventional scrambling method, only the subscriber's receiver can restore the synchronization signal (descrambling process) and display the video on the screen based on the synchronization signal. It is difficult to match the synchronization signal suppressed on the transmitting side accurately in time.
Therefore, synchronization disturbances may occur in the images displayed on the screen.

Furthermore, in conventional scrambling methods, it is necessary to suppress the synchronization signal level and to transmit the data necessary to restore the synchronization signal on the video signal of the scrambled channel. It required an additional circuit for decoding, and the descrambling circuit had the disadvantage of being complex and expensive. On the transmitting side, different data must be superimposed for each channel on the scrambled video signal of the channel, so the scrambling circuit in the transmitter is also complicated.

<Object of the Invention> An object of the present invention is to provide a video signal processing method that makes it difficult for non-contractors to illegally display images on a screen.

Another object of the present invention is to perform video scrambling processing by inverting the white level and black level of all video signals within a predetermined horizontal scanning period every horizontal scanning period without suppressing the synchronizing signal level on the transmitting side. This is achieved by providing a video signal processing method without synchronization that performs descrambling processing on the receiver side and displays the video on the screen.

Another object of the present invention is to identify whether or not the white level and black level of a video signal within one horizontal scanning period are inverted. This is done by superimposing an identification signal,
An object of the present invention is to provide a video signal processing method that does not require transmitting different data for each channel.

Still another object of the present invention is to provide a video signal processing method in which the scramble circuit and descramble circuit have simple configurations and are free from malfunctions due to noise.

<Summary of the Invention> Every horizontal scanning period, the white level and black level of all video signals within the horizontal scanning period are inverted randomly or according to a predetermined rule, and the horizontal synchronizing signal corresponding to the horizontal scanning period is inverted. An inverted identification signal is superimposed and transmitted to identify whether the white level and black level of the video signal have been inverted, and the receiving side identifies the inverted identification signal, and if they are inverted, the image is displayed for one horizontal scanning period. The original video signal is restored by inverting the signal's own level and black level.

According to this invention, it becomes difficult for non-subscribers to illegally display images on the screen, there is no malfunction due to synchronization or noise, and furthermore, the configuration of the scramble circuit and descramble circuit can be simplified.

<Embodiment> FIG. 1 is a block diagram of a pay television system for realizing the video signal processing method according to the present invention, and FIG. 2 is a waveform diagram of each part of FIG. 1. In Figure 1, TRM
is a transmitter, and RCV is a television receiver.

A video signal vps (see FIG. 2), which is a composite of the horizontal synchronization signal H2S, vertical synchronization signal, color burst signal CBS, etc., is output from the video source 11 and applied to the video scramble circuit 12 and the burst signal oscillator 13. The pulse generator 12a of the video scramble circuit 12 generates a horizontal synchronizing signal H2S included in the video signal VDS.
f, a narrow pulse PSt which is detected and outputted and delayed by a predetermined time from the falling time of the horizontal synchronizing signal;
b detects the color burst signal CBS included in the video signal VDF3, and during that time the burst gate signal BGS is detected.
t- occurs. The black and white level inversion control section 12C generates an inversion drive pulse PID and a gate pulse GP in synchronization with the horizontal synchronization pulse (IZS) randomly or according to a predetermined rule. Note that the gate pulse GP is generated for one horizontal opening signal period when the video signal VDS is inverted and output from the video scramble circuit 12. Further, the pulse width of the inversion drive pulse PID is one horizontal scanning period.

When the inversion drive pulse PID is at a low level, the gate section 12d outputs the video signal VDS at its i\small output, and when the inversion drive pulse PID is at a high level, it outputs the video signal VDS whose level has been inverted by the black and white level inversion circuit 12e. ' is output. Therefore, when the inverted drive pulse PID is generated as shown in FIG. 2, the gate part 12d outputs a video signal whose level is partially inverted in units of one horizontal scanning period, in other words, a scrambled video signal 5vDS. is output. The gate section 12f is a black and white level inversion control section 12.
While the gate pulse GP is being generated from C, it is open and the inverted identification pulse PIRi is generated.

The burst signal oscillator 13 receives the color burst signal CBS included in the video signal VDS while the burst gate signal BGS is at a high level, and operates to lock to the oscillation frequency of the color burst signal. That is, the burst signal oscillator 13 outputs a continuous color burst signal CBS' with no temporal interruption.

The synthesizing circuit 14 synthesizes the color burst signal CBS' into a scrambled video signal of 5 vps while the inverted identification pulse PrR is at a high level, and outputs the synthesized signal to the modulator 15. The modulator 15 amplitude modulates the scrambled video signal 5VD8' outputted from the synthesis circuit 14 and transmits it.

On the other hand, the receiver RCV receives the video signal transmitted from the transmitter TRM using the converter 21, and converts it into an IP-fold signal. The demosimulator 22 demodulates the converted IP multiplied signal,
The demodulated video signal 5VD8' is sent to a burst detection circuit 23, a synchronization detection circuit 24, and a black and white inversion recovery circuit 25.
to be applied. The burst detection circuit 23 uses a video signal of 5VDS.
Detects the color burst signal CBS included in ', and generates a high-level burst pulse BP during the synchronization detection circuit lf! 24 separates and outputs the horizontal synchronizing signal (IZS) included in the video signal 5VDS'.

The inverted identification pulse restoration circuit 26 performs an AND operation on the horizontal synchronizing signal 1z8 and the burst pulse BP to restore and output the inverted identification pulse FIR'. When the inverted drive pulse restoring circuit 27 receives the inverted identification pulse FIR', it restores and outputs the inverted drive pulse PID' having a half-scanning width in synchronization with the horizontal synchronizing signal HzS. Black and white inversion recovery circuit 25
outputs the video signal 5VDS' as it is when the inverted drive pulse PID' is low level, and outputs the video signal 5VDS' as it is, and
When D' is high level, the video signal S V D S
The black and white level of ' is inverted and output to the color burst signal extraction circuit 28.

The color burst signal sampling control section 29 controls the video signal VD.
A gate pulse for removing the color burst signal coming from the horizontal synchronization signal H2S of S" is applied to the color burst signal extraction circuit 28. As a result, the color burst signal extraction circuit 28 converts into a black and white inversion recovery circuit. The color burst signal is removed from the horizontal synchronizing signal portion of the video signal VDS" output from the buffer 3o, and the buffer 3o generates a restored video signal VDS. Thereafter, normal processing is performed using the video signal VDS to display the video on the screen. In addition, in FIG. 1, the color burst signal extraction control section 29 is removed and the inverted identification pulse restoration circuit 2 is replaced.
The inverted identification pulse PIR', which is the output of 6, is input to the color burst signal extracting 9 circuit 28, and the horizontal synchronizing signal H2
The color burst signal CBS carried by S may be extracted.

In addition, a case has been described in which a color burst signal is superimposed on the horizontal synchronization signal H2S to identify black and white inversion.
It does not necessarily have to be a color burst signal. However, when using a color burst signal, @) it is possible to accurately restore the synchronization signal when a synchronization signal suppression method (ink suppression) is used as video scrambling, and (←) it is easy to detect because it is an AC component. (c) There is no need to generate separate pulses to be superimposed, and the color burst signal that originally exists can be used, which is advantageous in terms of the number of parts.

<Effects of the Invention> As explained above, the transmitting side inverts the white level and black level of all video signals within a predetermined horizontal scanning period, and also provides an inversion identification signal to identify whether or not the horizontal synchronization signal has been inverted. The receiver side identifies the inverted identification signal, and if the signal is inverted, the white level and black level of the video signal are inverted for one horizontal scanning period to restore the original video signal. Therefore, it is difficult for non-subscribers to illegally restore the video signal, and by shifting the insertion position of the inverted identification signal, it can be made even more difficult for surreptitious viewing.

Also, there is no need to transmit different data for each channel, simply add a color burst signal to the horizontal synchronization signal,
Scramble circuits and descramble circuits can be simplified by simply instructing the inversion of black and white levels.

In particular, according to the present invention, since it is only necessary to superimpose an inversion identification signal on the horizontal synchronization signal corresponding to each horizontal scanning period, a memory element that stores information indicating whether the black and white level in a certain section is inverted or not is required. There is no need for a logic circuit to control the signal. Multi-bit digital data is transmitted together with the video signal, and there is no need to indicate which section the black and white level is inverted, making it easy to create scramble and descramble circuits. It can be configured as follows.

'Furthermore, since a black-and-white inversion identification signal is sent every horizontal scanning period, even if a malfunction occurs, the shadow will only be replaced in one horizontal scanning period, and the screen will not be disturbed and the synchronization will be maintained. It is also resistant to noise because color/<-st is superimposed on the signal.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a pay television system for realizing the video signal processing method according to the present invention, and FIG. 2 is a waveform diagram of each part of FIG. 1. DESCRIPTION OF SYMBOLS 11... Video source, 12... Video scramble circuit, 13... Burst signal oscillator, 14... Synthesizing circuit, 15... Modulator, 22... Demo simulator, 23... Burst detection circuit, 24 ... Synchronization detection circuit, 25... Black and white inversion recovery circuit, 26... Inversion identification pulse recovery circuit, 27... Inversion drive pulse recovery circuit, 28... Color burst signal extraction circuit Patent applicant Alps Electric Co., Ltd. Representative Patent Attorney Senki Saito Figure 1

Claims (2)

[Claims] (1) Invert the white level and black level of all video signals within a predetermined horizontal scanning period, and determine whether the white level and black level of the video signal have been inverted in the horizontal synchronization signal corresponding to the horizontal scanning period. An inverted identification signal for identification is superimposed and transmitted, the receiving side identifies the inverted identification signal, and if the inverted identification signal is inverted, the white level and black level of the video signal are inverted for one horizontal scanning period and the original image is reproduced. A video signal processing method characterized by restoring a signal. (2) the inverted identification signal is a color burst signal;
When the color burst signal is superimposed on the horizontal synchronization signal, it is determined that the white level and black level of the received video signal within one horizontal scanning period corresponding to the horizontal synchronization signal are inverted. video signal processing method.