JPH06315170A - Muse decoder - Google Patents

Abstract

PURPOSE:To provide a MUSE decoder where a motion detection circuit is not required, in the receiver of the high definition television signal which is band-compressed by an offset subsampling and is transmitted. CONSTITUTION:Each of the output signal of a still area processing circuit 2 and the output signal of a moving area processing circuit 3 is supplied to a spatial frequency power distribution analysis circuit 100. The spatial frequency power distribution analysis circuit 100 is composed of plural two-dimensional filters, detects the state of an input signal by the power distribution in a two-dimensional spatial frequency area and determines an optimum mixture ratio. The state of the signal is judged by the power distribution in the spatial frequency area of a signal itself for which a still area processing or a moving area processing is performed, and a motion detection circuit which has been necessary in a conventional MUSE decoder for determining the mixture ratio of the both of the processings becomes unnecessary.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a MUSE decoder for demodulating a high-definition television signal which has been band-compressed by offset subsampling and transmitted.

[0002]

2. Description of the Related Art One of the conventional methods for compressing and transmitting a wide band high-definition television signal into a practical level band that can be transmitted is a multiple sub-sampling transmission system using offset sub-sampling between frames and fields, For example, MUSE (Multiple Sub-Nyquist Sampling Encoding)
There is a method, and band compression is realized effectively (Ninomiya,
"High-definition TV satellite 1-channel transmission system" Technical Report TEBS 95-2 VOL7 No.44).

This system, as described in the paper, makes a cycle of a wideband high-definition television signal in four fields 4:
It is a method of compressing the band to about ¼ by performing sub-Nyquist sampling of 1 and transmitting. This compressed high-definition television signal (hereinafter referred to as MUSE signal) uses MUSE on the receiving side to interpolate sample point information that has not been transmitted, by using interpolation between fields, fields, and frames. The decoder restores the original broadband high-definition television signal.

FIG. 4 is a block diagram of a conventionally known MUSE decoder. In FIG. 4, 1 is an input processing circuit, 2
Is a static area processing circuit, 3 is a moving area processing circuit, 4 is a motion detection circuit, 5 is a mixing circuit, 6 is a TCI decoder, and 7 is a frame memory. The input MUSE signal is subjected to processing such as synchronization detection, audio signal separation, and control signal detection in the input processing circuit 1, and the input processed MUSE signal.
The signal is supplied to the stationary area processing circuit 2, the moving area processing circuit 3, the motion detection circuit 4, and the frame memory 7, respectively.

The frame memory 7 obtains a frame or field delay signal required for still area processing. The signals interpolated between the frames and between the fields in the static region processing circuit 2 are supplied to one input terminal of the mixer 5.
The signal interpolated in the field by the moving area processing circuit 3 is supplied to the other input terminal of the mixer 5. The motion detection circuit 4 detects the motion of the subject of the input signal, and for example, in the region determined to be a moving image, the mixer 5 selects the output signal of the moving region processing circuit 3. In the area determined to be a still image, the output signal of the still area processing circuit 2 is selected. Alternatively, they are mixed according to the amount of movement, and the signal in the TCI state is decoded to obtain the original high definition television signal.

As described above, in the MUSE decoder, different processing is performed for a still image and a moving image, and the mixing ratio of the two is determined according to the result of the motion detection, so that the performance of the motion detection circuit reproduces the quality of a high-definition television signal. It depends. Figure 5
FIG. 6 is a block diagram of a conventional motion detection circuit. In FIG.
42a and 42b are frame memories, 43 is a contour detection circuit, 44a and 44b are subtractors, and 45a and 45b.
Reference numeral b is an absolute value circuit, 46a and 46b are nonlinear processing circuits, 47 is a maximum value selection circuit, and 48 is a horizontal low-pass filter (hereinafter referred to as horizontal LPF).

The operation of the motion detection circuit configured as described above will be described. First, the input MUSE signal is delayed by one frame or two frames by the frame memory 42a and the frame memories 42b connected in cascade. Therefore, the subtractor 44a obtains a 1-frame difference signal and the subtractor 44b obtains a 2-frame difference signal. A horizontal LPF 48 is applied to the one-frame difference signal for the purpose of removing a high frequency component in which aliasing distortion due to inter-frame offset subsampling occurs, and the absolute value circuit 45a converts the signal into an absolute value and supplies the nonlinear processing circuit 46a.

The two-frame difference signal is converted into an absolute value in the absolute value circuit 45b and supplied to the non-linear processing circuit 46b.
On the other hand, the input MUSE signal is also supplied to the contour detection circuit 43, and the contour detection circuit 43 detects the contour signal. The contour detection circuit 43 is composed of, for example, a combination of a vertical high-pass filter and a horizontal high-pass filter. The detected contour signal is supplied to the non-linear processing circuits 46a and 46b, respectively. Non-linear processing circuit 46
In a and 46b, each frame difference signal is non-linearly processed into a motion signal of about 4 bits.

At this time, the motion detection sensitivity is controlled by the size of the contour. The control method lowers the motion detection sensitivity as the contour becomes larger. Subsequently, the motion signals based on the one-frame difference and the two-frame difference are supplied to the maximum value selection circuit 47, respectively. The maximum value selection circuit 47 compares the magnitudes of the input one-frame motion signal and two-frame motion signal, and selects the larger one and outputs it as a motion amount.

[0010]

However, in the structure of the motion detection circuit of the MUSE decoder as described above, the motion detection for one frame is performed by the LPF processing, and therefore the motion of the high frequency component cannot be detected. In addition, since there is a long time interval in motion detection between two frames, there are cases where motion cannot be detected.
As described above, it is extremely difficult for the MUSE decoder to accurately detect the movement of the input MUSE signal. In addition, in order to improve the detection accuracy, the circuit scale will be increased accordingly, leading to cost increase.

In view of the above problems, the present invention analyzes the power distribution in the spatial frequency domain of each output signal of the stationary domain processing and the dynamic domain processing, recognizes the state of the subject, and determines the optimum mixing ratio. MUSE without detection circuit
A decoder is provided.

[0012]

[Means for Solving the Problems] To achieve the above object,
The MUSE decoder of the present invention comprises a first reproducing means for performing interframe interpolation and interfield interpolation on an input signal, a second reproducing means for performing field interpolation on an input signal, and a first reproducing means.
And a mixing means for mixing the output signals of the second reproducing means. The output signal from the first reproducing means and the output signal from the second reproducing means are input, and the output signals of the respective The power distribution analysis means for analyzing the power distribution in the spatial frequency domain is provided, and the mixing means is controlled according to the power distribution in the spatial frequency.

[0013]

According to the present invention, the conventional MUSE decoder for judging the signal condition by the power distribution in the spatial frequency domain of the signal itself subjected to the static domain processing or the dynamic domain processing and determining the mixing ratio of the two is constructed by the above-mentioned structure. Then, the motion detection circuit, which was necessary, becomes unnecessary.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A MUSE decoder according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of a MUSE decoder in the embodiment of the present invention.

In FIG. 1, 1 is an input processing circuit, 2 is a static region processing circuit, 3 is a moving region processing circuit, 5 is a mixer, and 6
Is a TCI decoder, 7 is a frame memory, and 100 is a spatial frequency power distribution analysis circuit.

In FIG. 1, the input MUSE signal is subjected to processing such as synchronization detection, audio signal separation and control signal detection in the input processing circuit 1, and the input processed MUSE signal is processed in the stationary area processing circuit 2 and the moving area. It is supplied to the processing circuit 3 and the frame memory 7, respectively. In the frame memory 7, the still area processing circuit 2 obtains a frame or field delay signal required for interframe interpolation or interfield interpolation processing. The signals interpolated between the frames and between the fields in the static region processing circuit 2 are mixed by the mixer 5
Is supplied to one of the input terminals.

The signal interpolated in the field by the moving area processing circuit 3 is supplied to the other input terminal of the mixer 5.
The output signal of the mixer 5 is transmitted to the TCI decoder 6 by the TCI.
The state signal is decoded to obtain the original high definition television signal. The configuration so far is the same as that of the conventional MUSE decoder. The difference is that the output signals of the stationary region processing circuit 2 and the moving region processing circuit 3 are supplied to the mixer 5 and also to the spatial frequency power distribution analysis circuit 100, and the output signal of the spatial frequency power distribution analysis circuit 100 is used as the mixer. 5 is in control.

The spatial frequency power distribution analysis circuit 100 is composed of, for example, the circuit shown in FIG. In FIG. 2, 101-
106 is a filter, 107 to 112 are absolute value circuits, 11
Reference numerals 3 to 118 are comparators, and 119 is a mixing ratio determination circuit.
Each filter 1, filter 2, filter 3, ... Is 2
It is a one-dimensional or one-dimensional LPF or BPF. M
The spatial frequency domain transmitted in the USE system is as shown in FIG. 3, and the still and moving image transmission bands in FIG. 3 are divided by a plurality of filters. The output signal of each filter is converted into an absolute value and compared by the comparators 113 to 118 with a threshold value set separately for each comparator in advance. The value "0" is output. The comparison output from the comparator is supplied to the mixing ratio determination circuit 119. The mixing ratio determination circuit 119 is a logic circuit, and determines the state of the input image according to the logic value from each comparator.

For example, in the still area or moving area processing, the following four states occur depending on the image. (1) Still area static processing (2) Moving area still processing (3) Still area moving processing (4) Moving area moving processing (1) When still area static processing is performed, both horizontal and vertical directions are high. Has a large power distribution in the region.

(2) When the moving area is statically processed, the power is generally distributed in the low frequency range. However, when double image interference occurs due to the static image processing even though it is a moving image, it is in the middle and high frequencies. Has a power distribution.

(3) When the static area is subjected to dynamic processing, aliasing disturbance occurs due to interframe offset subsampling or interfield offset subsampling in diagonal lines or vertical lines. That is, it has a large power distribution in the diagonal high range and the horizontal high range. At this time, there is a large power distribution in the diagonal high range and the horizontal high range of the static processing output.

(4) When the moving region is subjected to the dynamic processing, it has a power distribution from the low region to the middle region. That is, in order to obtain a characteristic power distribution according to each state, the horizontal and vertical two-dimensional spatial regions are divided into a plurality of regions by using a two-dimensional filter, and each filter output is obtained by comparison with a threshold value. The state of the input signal can be inferred from the combination of the obtained logical values.
If the state of the input signal can be discriminated, the optimum mixing ratio is determined accordingly and used as the output signal of the spatial frequency power distribution analysis circuit 100. The output signal controls the mixer 5 of FIG.

As described above, by analyzing the power distributions of the output signals of the static region processing and the moving region processing in the two-dimensional space, the state of the input signal is detected and the optimum mixing ratio of the two is determined. The motion detection circuit becomes unnecessary.

A plurality of two-dimensional filters are used to detect the power distribution in the two-dimensional spatial frequency domain. However, the present invention is not limited to this, and time-division of two-dimensional discrete cosine transform, discrete Fourier transform, etc. It can also be detected using a frequency conversion method.

[0025]

As described above, according to the present invention, the first reproducing means for performing the inter-frame interpolation and the inter-field interpolation on the input signal and the second reproducing means for performing the field interpolation on the input signal. Is provided as an input, and power distribution analysis means for analyzing the power distribution of each output signal in the spatial frequency domain is provided, and the first reproduction means and the second reproduction means according to the power distribution in the spatial frequency are provided. With the configuration of controlling the mixing means for mixing the output signals, the power distribution of the output signals of the static region processing and the moving region processing is analyzed in the two-dimensional space to detect the state of the input signal and determine the optimum state of both. Since the mixing ratio is determined, the motion detection circuit is unnecessary.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a MUSE decoder according to an embodiment of the present invention.

FIG. 2 is a block diagram of a spatial frequency power distribution analysis circuit.

FIG. 3 is a diagram showing a transmission band in the MUSE system.

FIG. 4 is a block diagram of a MUSE decoder in a conventional example.

FIG. 5 is a block diagram of a motion detection circuit in a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Input processing circuit 2 Still area processing circuit 3 Moving area processing circuit 5 Mixer 6 TCI decoder 7 Frame memory 100 Spatial frequency power distribution analysis circuit

Claims (2)

[Claims] 1. A first reproducing means for performing inter-frame interpolation and inter-field interpolation on an input signal, a second reproducing means for performing field interpolation on the input signal, and the first reproducing means. A MUSE decoder having: and a mixing means for weight-mixing the output signals of the second reproducing means, wherein the output signal from the first reproducing means and the output signal from the second reproducing means are input. A MUSE decoder, characterized in that a power distribution analysis means for analyzing the power distribution of each output signal in the spatial frequency domain is provided, and the mixing means is controlled according to the power distribution in the spatial frequency domain. 2. The power distribution analyzing means receives a plurality of two-dimensional filters, a plurality of amplitude detecting means which receives output signals of the plurality of two-dimensional filters, and an output signal of the plurality of amplitude detecting means. The MUSE decoder according to claim 1, further comprising a logical operation means.