JPH04357785A - High definition television receiver - Google Patents

Abstract

PURPOSE:To reduce hardware by leading the output of a sampling frequency conversion circuit provided on a path for animation processing to a low-pass substitute circuit. CONSTITUTION:In a signal path 100 for animation processing, the arrangement is replaced as shown in a sampling frequency conversion circuit 13A and an intra-field interpolation circuit 12A. Further, the output of the sampling frequency conversion circuit 13A is inputted to a low-pass substitute circuit 22 as a signal S7 for low-pass substitute. In this case, the operation frequency of the intra-field interpolation circuit 12A shall be 48.6MHz, and the filter coefficient is different from that of the intra-field interpolation circuit 12, but the signal S4 is equivalent. Thus, the sampling frequency conversion circuit provided so as to obtain a signal S6 can be eliminated. Thus, the entire hardware can be reduced.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-definition television signal receiver having an improved decoder for demodulating a band-compressed high-definition television signal to the original wideband high-definition television.

0002

2. Description of the Related Art As a method for compressing the bandwidth of a wideband high-definition television signal to a level that is practical for transmission, MUSE (Multiple S
ub-Nyquist Sampling Encod
ing) method (``New transmission method for high-definition television - MUSE-'', NHK Giken Monthly Report, by Ninomiya, Vol. 27, No. 7, 1981).

[0003] A decoder is required to demodulate this band-compressed high-definition television signal (hereinafter referred to as a MUSE signal) into the original wideband high-definition television signal.

FIG. 4 shows a conventional decoder. The MUSE signal is supplied to input terminal 1 and introduced into interframe interpolation circuit 6 . This MUSE signal (hereinafter the signal at input terminal 1 will be referred to as S1) has a sampling rate of 16.2MHz.
It is. The interframe interpolation circuit 6 includes an input switching circuit 2 into which the MUSE signal is introduced, a first field memory 4 to which the output of this input switching circuit 2 (hereinafter this output will be referred to as signal S2), and It has a second field memory 5 to which the output of the first field memory 4 is supplied, and the output of the second field memory 5 is fed back to the input switching circuit 2. The input switching circuit 2 changes the signal S1 from the input terminal 1 by the control signal supplied from the terminal 3.
The signals from the second field memory 5 are selectively switched in units of sampling. Therefore, the first field memory 4 outputs a signal one field before the signal S1 and a signal three fields before the signal S1. Further, from the second field memory 5, a signal obtained by interpolating the signal two fields before the signal S1 and the signal four fields before the signal S1 is obtained.

Therefore, the signal S2 directly output from the input switching circuit 2 is a signal obtained by interpolating the MUSE signal (current field signal) of the input terminal 1 and the signal two fields before. This signal S2 has a sampling rate of 32.4 MHz.

[0006] The signal S2 is input to a pre-filter 7 for interfield interpolation, in this filter 0-12M
Frequency components up to Hz are extracted. Prefilter 7
The output signal is input to the sampling frequency conversion circuit 8, and the sampling rate is converted to 24.3 MHz. The output signal of the sampling frequency conversion circuit 8 is input to an interfield interpolation circuit 9. The interfield interpolation circuit 9 performs interfield interpolation processing at 48.6 MHz.
A signal S3 is obtained. This signal S3 is supplied to one input terminal of the mixing circuit 16.

The above interfield interpolation circuit 9 is shown in FIG.
It is considered ideal to perform filtering with the passband characteristics shown in A), but for example, if filtering is performed in such a way that the vertical high-frequency components are dropped, as shown in (B) of the same figure, Also, in order to replace the low-frequency components of the horizontal components with the current signal in the low-frequency replacement circuit 22, which will be described later, as shown in FIG. The high frequency components of are recovered.

Signal S2 output from input switching circuit 2
is also input to the signal extraction circuit 10. The signal sampling circuit 10 extracts only the data of the current field (signal S1 at the input terminal, 16.2 MHz rate) from the signal S2 based on the timing signal (subsampling phase signal) supplied from the terminal 11. Signal sampling circuit 1
The output signal of 0 is input to the intra-field interpolation circuit 12. The intra-field interpolation circuit 12 obtains a signal subjected to intra-field interpolation processing from the data of the current field. The intra-field interpolated signal is input to the sampling frequency conversion circuit 13 and converted to a rate of 48.6 MHz. This rate-converted signal S4 is sent to the mixing circuit 1
6 is supplied to the other input terminal.

The above signal S2 is also supplied to the motion detection circuit 14. The motion detection circuit 14 detects a motion image and supplies the detection signal to the sampling frequency conversion circuit 15. The sampling frequency conversion circuit 15 converts the motion detection signal to a rate of 48.6 MHz and supplies it to the mixing ratio control terminal of the mixing circuit 16.

As a result, the mixing circuit 16 outputs an output signal obtained by mixing the output signal S3 from the interfield interpolation circuit 9 and the output signal S4 from the sampling frequency conversion circuit 12 based on the motion detection signal. S5 is obtained. This signal S5 is input to the low frequency replacement circuit 22. A signal S6 obtained by converting the MUSE signal at the input terminal 1 to a rate of 48.6 MHz by the sampling frequency conversion circuit 24 is also input to the low frequency replacement circuit 22.

[0011] The low frequency replacement circuit 22 outputs a signal S5 and a signal S6.
It has a subtracter 17 to which is supplied. The output of the subtracter 17 is passed through a low pass filter (LPF) 18 to a multiplier 19.
After being multiplied by a coefficient according to a control signal from a terminal 20, the signal is input to an adder 21. This adder 2
A signal S5 is also input to the signal S1. This causes the signal S
The low frequency portion of signal S6 will be replaced with the horizontal low frequency portion of signal S6. The operation of the low frequency replacement circuit 22 is as follows. Still image processed signal S3 and moving image processed signal S4
Make the transition part less noticeable. The vertical resolution degraded by the interfield interpolation circuit 9 is restored. Two image quality improvement effects have been obtained.

The operation of the low frequency replacement circuit 22 will be further explained. In the low frequency substitution circuit 22, first, the subtracter 17 obtains a difference signal between the signals S5 and S6. The low-frequency component of this difference signal is extracted by a low-pass filter 18, and the multiplier 1
9, the resultant is multiplied by a coefficient and input to the adder 21. The multiplication coefficient sets the degree of low frequency replacement, and is
For example, when the output signal of the low-pass filter is small, the multiplication coefficient is controlled to be close to 1, and when the output signal of the low-pass filter is large, the multiplication coefficient is controlled to be close to 0. .

[0013]

[Problem to be solved by the invention] As explained above, M
In the USE signal decoder, the image quality is improved by replacing the low frequency portion of the output signal S5 of the mixing circuit 16 with the component on the input signal S1 side.

However, with this configuration, the sampling frequency conversion circuit 24 is required to create the signal S6 for replacement. Since the sampling frequency conversion circuit 24 tends to have a relatively large scale of hardware, it is preferable to reduce it as much as possible. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a high-definition television receiver that can reduce the amount of hardware and does not cause a decrease in performance.

[0015]

[Means for Solving the Problems] The present invention has a configuration in which the output of a sampling frequency conversion circuit provided in a video processing path that originally exists in order to decode a MUSE signal is guided to a low frequency replacement circuit. It is.

[0016]

[Operation] By the above means, it is possible to eliminate the sampling frequency conversion circuit conventionally used for low frequency replacement, and it is possible to reduce the amount of hardware.

[0017]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. The difference from the conventional circuit shown in FIG. 4 is the sampling frequency conversion circuit 13A in the signal path 100 for video processing.
As shown by the field interpolation circuit 12A, the arrangement is reversed from that of the circuit shown in FIG. Furthermore, the output of the sampling frequency conversion circuit 13A is input to the low frequency replacement circuit 22 as a signal S7 for low frequency replacement. In this configuration, the field interpolation circuit 12
Although the operating frequency of A is 48.6 MHz and the filter coefficients are different from those of the intra-field interpolation circuit 12 shown in FIG. 4, the signal S4 is equivalent to that of FIG. Furthermore, the sampling frequency conversion circuit 24, which was conventionally provided to obtain the signal S6, is eliminated. The other configurations are the same as the circuit shown in FIG. 4, and are given the same symbols as in FIG. 4.

In the embodiment configured as described above,
The signal processing performance is the same as that in FIG. However, since one sampling frequency conversion circuit is removed, the overall hardware can be reduced. FIG. 2 shows another embodiment of the invention.

The difference from the previous embodiment is that within the signal path 100 for video processing, the arrangement of the sampling frequency conversion circuit 13A and the intra-field interpolation circuit 12A is reversed. The output of the sampling frequency conversion circuit 13A is introduced into the low frequency replacement circuit 22 as a signal S7 for low frequency replacement.

In this embodiment, the signal S7 for low-frequency replacement passes through the intra-field interpolation circuit 12A, compared to the signal S6 for low-frequency replacement in FIG. In principle, the intra-field interpolation circuit 12A is a circuit with filtering characteristics as shown in FIG. 3(A), but in reality it has filtering characteristics as shown in FIG. Performs characteristic filtering. That is, the information of the vertical high-frequency component in the horizontal low-frequency component is left in the output signal of the intra-field interpolation circuit 12A with relatively no loss. Therefore, even with the configuration shown in FIG. 2, information remains relatively intact in the field interpolation circuit 12A. Therefore, even if the output of the intra-field interpolation circuit 12A is rate-converted by the sampling frequency conversion circuit 13A as in the embodiment shown in FIG.
It is possible to recover the degraded vertical resolution. Furthermore, since the low-frequency replacement signal used in this case is a signal of the latest field, the effect of making the transition between a still image and a moving image less noticeable can be obtained.

[0022]

[Effects of the Invention] As explained above, according to the present invention,
Hardware reduction can be obtained without reducing performance.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a circuit diagram showing another embodiment of the invention.

FIG. 3 is a frequency characteristic diagram shown to explain the operation of the circuit in FIG. 2;

FIG. 4 is a circuit diagram showing a conventional MUSE decoder.

FIG. 5 is a frequency characteristic diagram shown to explain the operation of the circuit in FIG. 4;

[Explanation of symbols]

2... Input switching circuit, 4, 5... First and second field memories, 6... Interframe interpolation circuit, 7... Prefilter,
8, 13A, 15...sampling frequency conversion circuit, 9...
Interfield interpolation circuit, 10...Signal sampling circuit, 12A
...Field interpolation circuit, 14...Motion detection circuit, 16...
Mixing circuit, 22...low frequency replacement circuit.

Claims (2)

[Claims] Claim 1: In a decoder section that demodulates the band-compressed high-definition television signal by subsampling that goes around in n fields into the original broadband high-definition television signal, the band-compressed high-definition television signal is demodulated into the original broadband high-definition television signal. a first field memory for storing n/2 fields and a second field memory for storing n/2 fields, and means for performing interframe interpolation processing on a high-definition television signal for the n fields; , a first sampling rate conversion means for converting the sampling rate of the high-definition television signal output from the interframe interpolation processing means; and interfield interpolation for the output signal of the first sampling rate conversion means. inter-field interpolation processing means for performing processing; second sampling rate conversion means for introducing the latest one field signal of the band-compressed high-definition television signal and converting its sampling rate; Intra-field interpolation processing means for performing intra-field interpolation processing on the output signal of the sampling rate conversion means; and motion detection means for detecting moving parts from the high-definition television signal output from the inter-frame interpolation processing means. and mixing means for mixing the output signal of the inter-field interpolation processing means and the output signal of the intra-field interpolation processing means at a ratio based on the output of the motion detection means, and a signal output from the mixing means. 1. A high-definition television signal receiver comprising: low-frequency replacement means for replacing part or all of the low-frequency portion of the second sampling rate conversion means with the output signal from the second sampling rate conversion means. [Claim 2] A high-definition television signal band-compressed by subsampling that goes around n fields,
In the decoder section that demodulates the original broadband high-definition television signal, a first field memory stores n/2 fields of the band-compressed high-definition television signal, and a second field memory stores n/2 fields of the band-compressed high-definition television signal. interframe interpolation processing means for performing interframe interpolation processing on the high-definition television signal for the n fields; a first sampling rate conversion means for converting the sampling rate; an interfield interpolation processing means for performing interfield interpolation processing on the output signal of the first sampling rate conversion means; The latest television signal
Intra-field interpolation processing means for performing intra-field interpolation processing based on a field signal; and second sampling rate conversion means for converting the sampling rate of a high-definition television signal output from the intra-field interpolation processing means. and a motion detection means for detecting a moving part from a high-definition television signal output from the inter-frame interpolation processing means, and a ratio based on the output of the motion detection means, the inter-field interpolation processing means and the mixing means for mixing the output signals of the second sampling rate conversion means; 1. A high-definition television signal receiver, characterized in that it is equipped with area replacement means.