JP2927821B2 - High-definition television signal decoding device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-definition television signal decoding apparatus, and more particularly to a broadcast wave (analog form) of a high-definition television signal represented by a MUSE signal. The present invention relates to a high-definition television signal decoding device suitable for decoding a digital high-definition television video signal that has once passed through an analog system, such as a signal obtained by recording the converted signal on a digital VTR.

(Summary of the Invention) The present invention relates to an apparatus for decoding a high-definition television signal such as a MUSE signal, and more particularly to an apparatus for decoding a digital high-definition television signal which has been transmitted via an analog transmission system and then digitized. A circuit for extracting a high-frequency component of a digital high-definition television signal when an input digital high-definition television image signal is not emphasized, and using the extracted high-frequency component as a control signal for decoding It is made possible. Also, the present invention provides a digital high-definition television signal input to the MUSE decode.
This is particularly effective in the case of the bit mode.

Thus, a digital high-definition television signal having a history once converted into an analog signal can be completely decoded.

2. Description of the Related Art Conventionally, in decoding a high-definition television signal represented by a MUSE signal, a MUSE signal input to a decoder is a signal digitally processed through the entire system, that is, a digitally processed signal on an encoder side, and the decoder is used as it is. It has been found that 8-bit signal processing can provide sufficient accuracy for signals of digital origin that have reached the side.

However, when a signal digitally processed on the encoder side is converted into an analog signal and transmitted once through an analog transmission system such as an FM system with emphasis, and then re-digitized and processed on the decoder side, a 10-bit signal is used. Accuracy is required. The reason for this is that distortion generated in the transmission system concentrates on the edge portion of the image, and if this is to be removed by signal processing, it is necessary to extract a non-linear edge signal for detecting that portion.

Therefore, in the conventional MUSE signal decoder, if the received input signal is like a broadcast wave, the digitized signal is
It is handled with 10 bits. This means that when applied to a digital VTR that directly records high-definition television signals for recording in a studio without using an analog transmission system (FM), it is necessary to record two bits of extra information. It is uneconomical.

The same is true for DPCM (Differential Pulse Code
Modulation) and the like, and can also be applied to a MUSE digital signal transmitted via a band compression transmission path.

(Problem to be Solved by the Invention) Here, in order to clarify the problem to be solved by the present invention, the configuration of a decoder in a normal MUSE receiver will be briefly described. See Development of Method, NHK Technical Research, Vol. 39, No. 2, pp. 18-53 (1987).

FIG. 4 shows an outline of a conventional MUSE decoder configuration.
FIGS. 5A, 5B, 5C and 5D show the signal waveforms after the processing of each constituent block, and FIGS.
Here, only the parts necessary for the description according to the present invention are shown.

In FIG. 4, an input MUSE signal transmitted by FM with emphasis is subjected to A / D conversion by an A / D converter A / D, and is subjected to nonlinear processing by a next nonlinear circuit NL as a 10-bit signal. This non-linear processing extends the beard portion W of the signal transmitted with emphasis (FIG. 5 (b)), but at the same time, the bigger portion W is most susceptible to transmission distortion.
In order to treat the signal processing at the subsequent stage of the decoder differently from other parts, a nonlinear edge signal is extracted in the nonlinear circuit NL, and the sensitivity of the motion detection at the subsequent stage of the encoder is reduced according to the extracted signal. And so on. On the other hand, the signal of the main line in which the nonlinear processing is performed by the nonlinear circuit NL and the bigger portion W is expanded is subjected to de-emphasis processing by the de-emphasis filter DEF of the next stage, and an 8-bit M signal is output.
The USE digital signal is transferred to the subsequent stage of the decoder.

The analog MUSE signal transmitted as shown in FIG. 4 is digitized by an A / D converter A / D and
When the digital signal is input to the decoder, if the digital signal is input with 8 bits (for example, the digital signal reproduced and recorded after recording the 8-bit MUSE digital signal on the digital VTR described later) as described above, This signal is shown in the 4th de-emphasis filter
The signal is input at the position of the output of DEF, and the subsequent signal processing is performed as a signal that has already been de-emphasized.

At this time, if the input digital signal is not subjected to transmission distortion at all, such as a signal directly obtained without going through an analog transmission system, such as a signal encoded on the encoder side, the processing of the nonlinear edge signal is unnecessary. Therefore, there is no problem. However, in the case of a signal which is transmitted after being subjected to non-linear processing as in the case of receiving a broadcast wave and undergoing transmission distortion, subsequent signal processing is incomplete if the signal is left as it is.

Therefore, an object of the present invention is to solve the above-mentioned problem and to provide an analog system such as a signal obtained by recording a broadcast wave (analog form) of a high-definition television signal represented by a MUSE signal on a digital VTR. And a high-definition television signal decoding apparatus suitable for decoding a digital signal transmitted through the digital video signal.

(Means for Solving the Problems) In order to achieve this object, the high-definition television signal decoding apparatus of the present invention encodes in a motion-compensated multiplex sub-sample band compression transmission form, emphasizes the analog transmission, A nonlinear circuit for extending a preshoot and an overshoot of an edge signal of a digital digitized high-definition television video signal received and extracting and outputting a nonlinear edge signal as a control signal for decoding; A high-definition television signal decoding device including a de-emphasis filter for performing de-emphasis processing on an edge signal having an expanded shoot and outputting the signal, wherein the input digital high-definition television video signal is a signal without emphasis To A non-linear edge signal generation circuit for extracting a high-frequency component of the input digital high-definition television video signal and outputting the extracted high-frequency component as a control signal upon decoding;
A switcher for switching and outputting the input digital high-definition television image signal in place of the output signal of the de-emphasis filter when the input digital high-definition television image signal is a signal without emphasis; and the nonlinear circuit And a switch for switching and outputting the output signal of the non-linear edge signal generation circuit in place of the output signal.

(Operation) According to the decoding apparatus of the present invention, in an apparatus for decoding a digital high-definition television signal which has been transmitted through an analog transmission system and then digitized, the input digital high-definition television video signal is emphasis-encoded. A circuit for extracting the high frequency components of the digital high-definition television signal is provided when it is not applied, so that the extracted high frequency components can be used as a control signal for decoding, and the digital high-definition signal can be used. Even when the television signal is in the 8-bit mode, the signal processing at the edge portion of the image is satisfactorily achieved similarly to the signal in the 10-bit mode.

(Example) Hereinafter, the present invention will be described in detail by way of examples with reference to the accompanying drawings.

 FIG. 1 shows the configuration of an embodiment according to the present invention.

In this case as well, only the parts necessary for the explanation according to the present invention are shown in the same manner as in the conventional configuration shown in FIG.

In the example shown in FIG. 1, both the 8-bit mode and the 10-bit mode can be used as the digitized input of the MUSE signal.
Since S ₂ and S ₃ are tilted upward to perform the same signal processing as the signal input in the analog mode, it is not relevant to the following discussion.

The high-pass filter HPF and the non-linear edge detector NED in the figure correspond to the non-linear edge signal generation circuit of the present invention, and the HPF is a filter for re-emphasis, N
ED is a nonlinear edge detection circuit (comparator) for extracting a nonlinear edge portion W in FIG.

The high-pass filter HPF is a filter corresponding to the emphasis of the transmission system, but it need not be exactly the same as that used for it, and the emphasis filter of the MUSE signal has a large tap coefficient concentrated near the center tap. Since this type is adopted, a simple three-tap transversal type as shown in FIG. 3 is sufficient.

2 (a), 2 (b) and 2 (c) show waveforms of respective parts of the configuration shown in FIG. FIG. 3 shows an embodiment in which a portion constituting a control signal from a digital mode signal in the configuration shown in FIG.
In the embodiment shown in FIG. 3, the switch S1 shown in FIG. ₁ is switched by switching a tri-state buffer. Also Z in the figure
^-1 is a one-clock delay circuit, and + is 1 /
ABS includes an absolute value circuit, CA denotes a comparator array, a CC encoding circuit, and DL denotes a delay circuit. Note switch S ₄ in the figure in the case of complete digital origin signal can of course defeat upward.

(Effect of the Invention) As described above, according to the decoding apparatus of the present invention, for example, a digital MUSE having a history once converted into an analog signal, such as a home A / D conversion VTR output signal, is used.
The signal can also be completely decoded.

At the same time, this means that VTR and VDP signals for analog recording can be transferred from a player in an 8-bit digital mode.

[Brief description of the drawings]

FIG. 1 shows a configuration of an embodiment according to the present invention, FIG. 2 shows signal waveforms of respective parts of the configuration shown in FIG. 1, and FIG. 3 shows a control signal from a digital mode signal in the configuration shown in FIG. 4 shows a configuration example of a conventional MUSE decoder, and FIG. 5 shows a signal waveform of each part of the configuration shown in FIG. A / D ...... analog-to-digital converter NL ...... nonlinear circuit DEF ...... deemphasis filter HPF ...... highpass filter NED ...... nonlinear edge detection circuit _{S 1, S 2, S 3} , S 4 ...... changeover switch Z ^{- 1} … 1 clock delay circuit ABS… Absolute value circuit CA… Comparator array CC… Encoding circuit DL …… Delay circuit

Claims (2)

(57) [Claims] 1. A preshoot and an overshoot of an edge signal of a digital high-definition television image signal which has been encoded into a motion-compensated multi-subsample band compression transmission form, emphasized and analog-transmitted, and then received and digitized. A nonlinear circuit that expands and extracts and outputs a nonlinear edge signal as a control signal at the time of decoding; and a de-emphasis filter that performs de-emphasis processing on the edge signal in which the preshoot and overshoot have been expanded and outputs the result. In the high-definition television signal decoding device, when the input digital high-definition television video signal is a signal without emphasis, extracting a high-frequency component of the input digital high-definition television video signal;
A non-linear edge signal generating circuit for outputting the extracted high-frequency component as a control signal for the decoding; and an output of the de-emphasis filter when the input digital high-definition television video signal is a signal without emphasis. A switching unit that switches and outputs the input digital high-definition television image signal instead of a signal, and a switch that switches and outputs the output signal of the nonlinear edge signal generation circuit instead of the output signal of the nonlinear circuit. A high-definition television signal decoding device characterized by the above-mentioned. 2. The high-definition television signal decoding apparatus according to claim 1, wherein said nonlinear edge signal generation circuit includes a three-tap transversal type high-pass filter.