JP2003069915A - Digital broadcast receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a digital broadcast receiver that can quickly cope with a deteriorated video image without giving a sense of incongruity to a viewer on the occurrence of the deteriorated video image due to a deteriorated reception environment. SOLUTION: When the reception environment of the digital broadcast receiver and a video image deterioration detection circuit 10 detects a decrease in a reception level, a display device 15 displays a message such as 'a corrected video image is displayed because the reception state is deteriorated at present' when a video image correction circuit 12 corrects the video image, and also the display device 15 displays a message such as 'sound is tentatively interrupted' together with message above. The video image correction circuit 12 reads a frame image of only I picture or of I and P pictures and applies correction to the frame image without reading a frame image of B picture much deteriorated as its control.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital broadcast receiver capable of promptly responding to an image deterioration caused by deterioration of receiving environment without giving a feeling of strangeness to a viewer.

[0002]

2. Description of the Related Art A digital broadcast receiver is an MPEG (Mo
Ving Picture Expert Grou
p), the video data compressed and encoded by the video decoding
The video signal is decoded and output to the display. In the MPEG system, bidirectional prediction is performed in order to improve the prediction efficiency of motion compensation. In order to perform such bidirectional prediction, image data is I (Intra-code).
d), P (Predictive-coded), B
(Bidirectionally predicti
ve-coded).

An I picture is an intra-frame predictive coded image in which an input signal is coded as it is without using inter-frame prediction. A P-picture is a forward inter-frame predictive coded image generated using inter-frame prediction from an I-picture or P-picture using unidirectional motion-compensated prediction. . Furthermore, the B picture is
2 is a bi-directional inter-frame predictive coded image generated using bi-directional inter-frame prediction.

In a digital broadcasting receiver, when the receiving environment is deteriorated, for example, when the receiving electric field is suddenly changed, the image data is disturbed or distorted to deteriorate the received image. Especially when the digital broadcast receiver is mounted on a moving body such as a vehicle,
Since the vehicle may run near high-rise buildings or mountain slopes, steep fluctuations and instantaneous interruptions of received radio waves occur.

[0005]

When the received image deteriorates and cannot be restored to a normal image, a message screen prepared in advance is displayed on the display. In this way, when the received video is significantly degraded, the display on the display suddenly switches from the video that was being viewed so far to a different video, causing viewers to feel discomfort and the video being viewed is interrupted. There was a problem that the taste was lost.

The present invention has been made in view of the above circumstances, and in the case where image deterioration occurs due to deterioration of the receiving environment, a digital broadcast image can be continuously viewed without giving discomfort to the viewer. The purpose is to provide a broadcast receiver.

[0007]

SUMMARY OF THE INVENTION The above-mentioned object is to provide a digital broadcast receiver for decoding the received digital broadcast wave and outputting the decoded video data to a display in the invention according to claim 1. In the above, a video correction means for detecting the reception level of the received digital broadcast wave and correcting the video data according to the degree of the decrease in the reception level, and a process for coping with the decrease in the reception level are performed. This is achieved by providing an output means for outputting a signal for notifying the viewer.

According to the first aspect of the present invention, there is provided the signal output means for notifying the viewer that the process for coping with the decrease in the reception level is being performed. Therefore, the viewer obtains the information that the digital broadcast receiver is performing the processing for dealing with the deterioration of the reception environment.
You can continue watching digital broadcast images without feeling anxious or uncomfortable.

According to a second aspect of the present invention, in the digital broadcast receiver according to the first aspect, the output means outputs a signal notifying a viewer that the corrected image is displayed on the display. It is characterized by that.

According to the invention of claim 2, the viewer is
The digital broadcast receiver corrects the image in order to cope with the deterioration of the reception environment, and acquires information that the corrected image is displayed on the display. Therefore, even if the image quality of the image displayed on the display changes slightly, it is possible to continue viewing the image of the digital broadcast without feeling discomfort.

According to a third aspect of the present invention, in the digital broadcast receiver according to the first aspect, the output means outputs a signal notifying the viewer that the audio of the received digital broadcast wave is temporarily suspended. It is characterized by outputting.

According to the invention of claim 3, the viewer is
The digital broadcast receiver acquires information that the audio being broadcast is temporarily interrupted as the reception environment deteriorates.
For this reason, unnecessary operations to recover the voice,
No more worries about device performance.

According to a fourth aspect of the present invention, in the digital broadcast receiver according to the first aspect, the corrected image is displayed on the display by the output means, and the audio of the received digital broadcast wave is displayed. It is characterized by outputting a signal for notifying the viewer that the image is temporarily suspended.

According to the invention of claim 4, the viewer is
Digital broadcast receivers correct the video to cope with the deterioration of the reception environment, and obtain information that the corrected video is displayed on the display and that the audio being broadcast is temporarily interrupted. To do. Therefore, even if the quality of the image displayed on the display changes slightly or the sound is temporarily interrupted, the user can continue watching the digital broadcast image without feeling discomfort or performing unnecessary operations for sound recovery. be able to.

According to a fifth aspect of the present invention, in the digital broadcast receiver according to any one of the first to fourth aspects, the correction by the video correction means is performed by intra-frame predictive coding image and forward frame. − Video data with inter-frame predictive coded image
It is characterized by forming the data.

According to the invention of claim 5, when the reception environment is deteriorated and the reception level is lowered to some extent, the intra-frame predictive coded image and the forward frame with less degree of video deterioration are obtained. Video data can be formed from the inter-prediction coded image. Therefore, the viewer can view the image of the digital broadcast that is being broadcast without feeling discomfort.

According to a sixth aspect of the present invention, in the digital broadcast receiver according to the fifth aspect, the correction by the video correction means is performed in accordance with the degree of decrease in the reception level, the intra-frame predictive coded image and the forward direction. The feature is that the ratio of application of the inter-frame predictive coded image is changed.

According to the sixth aspect of the invention, when the reception environment deteriorates and the reception level decreases, the viewer receives the intra-frame predictive coded image and the forward direction according to the degree of the decrease in the reception level. The information that the application ratio of the inter-frame predictive coded image is changed is acquired. . Therefore, the viewer recognizes that the image data is formed in the optimum state, despite the lowered reception level, and can continue to view the image of the digital broadcast with a sense of security.

According to a seventh aspect of the invention, in a digital broadcast receiver for decoding the received digital broadcast wave and outputting the decoded video data to a display, the reception level of the received digital broadcast wave is detected, When the degree of decrease in the reception level is small, the bidirectional inter-frame predictive coded image is removed to form the video data.

According to the invention of claim 7, when the reception environment is deteriorated and the reception level is reduced, the bidirectional inter-frame predictive coded image is removed when the degree of the reduction of the reception level is small. Form the video data. Therefore, it is possible to provide the viewer with video data that is practically unimpeded.

According to an eighth aspect of the invention, in a digital broadcast receiver for decoding the received digital broadcast wave and outputting the decoded video data to a display, the reception level of the received digital broadcast wave is detected, A video correction means for correcting video data according to the degree of decrease of the reception level is provided, and intra-frame predictive coded image and forward inter-frame predictive coding are provided according to the degree of decrease of the reception level. It is characterized by changing the application rate of images.

According to the eighth aspect of the present invention, the ratio of application of the intra-frame predictive coded image and the forward inter-frame predictive coded image is changed according to the degree of decrease in the reception level. Therefore, in accordance with the degree of decrease in the reception level, the video data in which the ratio between the intra-frame predictive coded image and the forward inter-frame predictive coded image is set to the optimum ratio is formed and viewed. Can be provided to other people.

According to a ninth aspect of the present invention, in a digital broadcast receiver that decodes a received digital broadcast wave and outputs the decoded video data to a display, the reception level of the received digital broadcast wave is detected, It is characterized in that the bidirectional inter-frame predictive coded image and the forward inter-frame predictive coded image are removed to form video data when the degree of decrease in the reception level is intermediate. .

According to the invention of claim 9, the bidirectional inter-frame predictive coded image and the forward inter-frame predictive coded image are removed when the degree of decrease in the reception level is intermediate. Thus, the video data is formed only by the intra-frame predictive coded image. For this reason, it is possible to provide the viewer with video data with a small degree of deterioration in image quality.

According to a tenth aspect of the invention, in a digital broadcast receiver which decodes a received digital broadcast wave and outputs the decoded video data to a display, the reception level of the received digital broadcast wave is detected, When the degree of decrease in the reception level is large, video data including an intra-frame predictive coded image, an inter-frame predictive coded image, and a forward inter-frame predictive coded image is formed. Instead, it is characterized by outputting a signal for displaying a fixed message on the display.

According to the tenth aspect of the present invention, when the degree of decrease in the reception level is large, the image data is not formed and the signal for displaying the fixed message on the display is output. Therefore, it is possible to provide the viewer with information that the digital broadcast cannot be viewed due to the deterioration of the reception environment.

The invention according to claim 11 is the digital broadcast receiving apparatus according to any one of claims 1 to 4 or claim 9, wherein the correction by the video correction means is intraframe predictive coding. It is characterized in that noise is reduced by a frame recursive filter for video data formed by only images.

According to the eleventh aspect of the present invention, when the reception environment deteriorates, the frame cyclic filter removes noise from the video data formed only by the intra-frame predictive coded image. It is reducing. Therefore, when the image deteriorates due to the deterioration of the reception environment, the display image is stabilized,
Viewers can enjoy high quality digital broadcast images.

According to a twelfth aspect of the present invention, in the digital broadcast receiver according to any one of the first to eighth aspects, the correction by the video correction means is performed by intra-frame predictive coding image and forward frame. It is characterized in that noise is reduced by a frame recursive filter for video data formed by an inter-frame prediction coded image.

According to the twelfth aspect of the present invention, when the reception environment is deteriorated and the reception level is lowered to some extent, noise is further added to the corrected video data by the frame cyclic filter. It is reducing. For this reason, the display image is stabilized when the image is slightly deteriorated due to the deterioration of the reception environment, so that the viewer can watch the image of the digital broadcast in which the deterioration of the image quality is hardly felt.

According to a thirteenth aspect of the present invention, in the digital broadcasting receiver according to any one of the first to fourth aspects or the ninth aspect, the correction by the image correction means is:
Noise is reduced by filtering with an averaging filter between the frame image before the reception level is lowered and the intra-frame predictive coded image read from the video data after the reception level is lowered. I am trying.

According to the thirteenth aspect of the present invention, when the reception environment deteriorates, the frame image before the reception level is lowered and the video data formed by the intra-frame predictive coded image are recorded. The noise is reduced by filtering with the averaging filter. For this reason, the viewer can view the image of the digital broadcast with little deterioration in image quality.

According to a fourteenth aspect of the present invention, in the digital broadcast receiver according to any one of the first to eighth aspects, the correction by the video correction means is performed by intra-frame predictive coding image and forward frame. It is characterized in that noise is reduced by the averaging filter with respect to the video data formed by the inter-frame prediction coded image.

According to the fourteenth aspect of the present invention, when the reception environment is deteriorated and the reception level is lowered to some extent, noise is further reduced by the averaging filter with respect to the corrected video data. There is. For this reason, the viewer can view the image of the digital broadcast with almost no deterioration in image quality.

According to a fifteenth aspect of the present invention, in the digital broadcast receiver according to the first aspect, when the correction by the image correction means continues for a certain period of time, a message screen created in advance is displayed on the display. It is characterized by displaying images.

According to the fifteenth aspect of the invention, when the reception environment is deteriorated and the reception radio wave is blocked for a long time, the effect of the image correction may not be expected, and a message to that effect is displayed.
The image is displayed on the screen. Therefore, the viewer can wait until the information about the reason why the video of the digital broadcast cannot be viewed and the normal state is restored.

[0037]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic block diagram showing a digital broadcast receiving apparatus according to an embodiment of the present invention. In FIG. 1, a digital broadcast receiver 1 receives a digital broadcast wave by an antenna 2, and tunes a tuner 3 to select one broadcast wave.

This broadcast wave is transmitted from a broadcasting station by QPSK modulation (Quadrature Phase Shift Ke).
Ying) signal, and includes video data compressed and encoded by the MPEG system as described above. The signal received by the antenna 2 is output from the tuner 3.
The output signal of the tuner 3 is input to the digital demodulation circuit 4 and digitally demodulated.

The signal digitally demodulated by the digital demodulation circuit 4 is input to the error correction circuit 5 for error correction. Next, the scramble canceling circuit 6 cancels the scramble. M output from the descrambling circuit 6
The data multiplexed according to the PEG system standard is separated into an MPEG audio signal and an MPEG video signal by a data demultiplexing circuit 7.

The MPEG audio signal is an MPEG audio signal.
The audio decoder 8 decodes the baseband audio signal. The decoded audio signal is output as sound from the speaker 14. MPEG video signal is MP
The EG video decoder 9 decodes the base band video signal. When the reception condition is good, the decoded video signal is stored in the image memory 13 as it is.

The image deterioration detection circuit 10 detects a decrease in the reception level based on the C / N ratio (carrier to noise ratio), and inputs the signal to the image correction circuit 12. When the reception environment deteriorates and the video deterioration detection circuit 10 detects a decrease in the reception level, the base band video signal decoded by the MPEG video decoder 9 is corrected by the video correction circuit 12 and stabilized. . The image deterioration detection circuit 10 detects the degree of decrease in the reception level based on the degree of error in the received image data.

In the image correction circuit 12, when the degree of decrease in the reception level is relatively small (when the degree of decrease in the reception level is small), the image of the image is detected based on the detection signal input from the image deterioration detection circuit 10. Determining the degree of decrease in the reception level, as in the case where restoration is possible (when the degree of decrease in the reception level is in the middle) and when restoration of video is not possible (when the degree of decrease in the reception level is large) However, as will be described later, image correction is performed by various measures according to the degree of decrease in the reception level.

The video signal corrected by the video correction circuit 12 is stored in the image memory 13. Memory control 11
Outputs a video signal without deterioration from the image memory 13 or a video signal corrected by the video correction circuit 12 and outputs the video signal to the display 15. The display 15 displays the video signal as a video.

Although not shown, the digital broadcast receiver 1 has a built-in microcomputer. This microcomputer forms a part of each of the above-mentioned constituent circuits or controls the operation of each constituent circuit. Further, as will be described later, it outputs signals for notifying various messages when the reception level is lowered.

FIG. 2 is an explanatory diagram showing an example of video data. FIG. 2A shows the original image in A of FIG. 1 before being decoded by the MPEG video decoder 9. Figure 2
As shown in (a) of the above, the video data compressed by the MPEG system is coded video data composed of three types of pictures: I picture, P picture, and B picture.
Is formed as

FIG. 2B shows the video data in B of FIG. 1 decoded by the MPEG video decoder 9. As shown in (b) of FIG. 2, the video data of 15 frames has GOP (Group Of Pict).
ures) structure. An I picture appears once in a GOP, and a P picture and a B picture appear multiple times. Also, by changing the order of each picture, I
The picture is read in the first frame image of the GOP. In this way, since the I-picture frame image is decoded into the GOP head frame image, editing and random access can be performed in GOP units.

FIG. 3 is an explanatory view of the basic principle of the present invention. FIG. 3A shows the video data in B of FIG. In each frame image of Fn-15 to Fn-30, the I, P and B pictures are arranged as described above, and each G image is arranged.
An I picture frame image is read as the first frame image of OP. When the reception environment deteriorates and the deterioration of the reception level is detected by the image deterioration detection circuit 10 at the timing of time ta, the signal level of FIG. 1D changes from L to H as shown in FIG. 3C. Change.

The signal that has detected the decrease in the reception level is
It is input to the image correction circuit 12. The video correction circuit 12 controls so that an I picture frame image is read out from each frame image. That is, as shown in FIG. 3B, the IOP frame image of GOP is read as it is. Further, when reading the P-picture and B-picture frame images, the I-picture frame image is read instead.

As described above, by repeatedly displaying the image only for I-pictures having a small degree of image deterioration during the period in which the decrease in the reception level is detected, the viewer can watch the image being broadcast without interruption. You can continue watching. At this time, due to the decrease in the reception level, the voice is temporarily interrupted and put into a muted state. In addition,
The audio mute interrupts the output of the MPEG audio decoder 8 or the output of an amplifier circuit (not shown) connected to the subsequent stage of the MPEG audio decoder 8. Can be realized.

When the image correction circuit 12 corrects the image due to the decrease in the reception level, the message on the screen of the display 15 is "A reception image is currently bad, so the corrected image is displayed." -Display the message. Also,
A message such as "Voice is suspended" is also displayed. Instead of displaying the message on the display 15, a pre-recorded voice message may be used to notify that the processing for coping with the decrease in the reception level is being performed. In this case, the audio processing unit is separately connected to the digital broadcast receiver.

It is also possible to install an LED on the digital broadcast receiver 1 or the display 15 and make the LED blink to notify the viewer that the process for coping with the decrease in the reception level is being performed. A signal to notify the viewer by displaying a message on the display, a voice message, blinking by an LED, etc. is output from a microcomputer incorporated in the digital broadcast receiver 1. By providing the output means of the signal for notifying such a decrease in the reception level, the viewer can obtain the information about the reason why the display state of the image is slightly different from the past, and the reason why the audio is interrupted. , You can continuously watch images without feeling discomfort.

In the example of FIG. 3, the frame image of only the I picture is read and displayed on the display while the reception level is low. In the present invention, when the degree of decrease in the reception level detected by the video deterioration detection circuit 10 is small, instead of reading only the I-picture frame image, an I-picture frame image is read. P
A picture frame image can be read out.

Such a structure has the I-picture of GOP-
Frame picture of P picture and P frame picture of P picture are read as they are, and when reading the frame picture of B picture having a large degree of deterioration, I picture is replaced with the frame picture of B picture. This can be realized by reading the frame image of. In this case, only I picture and B picture are interchanged.

Therefore, the number of pictures to be corrected is smaller than that in the case where all GOP frame images are corrected to I pictures as in the case of FIG. Image correction processing can be performed easily. In this way, the degree of correction can be controlled by adjusting the type of image to be read according to the degree of deterioration. Further, when the video data is formed by the I picture frame image and the P picture frame image, these frames are formed.
It is also possible to adjust the proportion of the video image according to the degree of deterioration.

By the way, it is known that a video signal has a very high correlation between frames. On the other hand, noise is considered to be a random signal because there is no correlation between frames. Therefore, by using the frame recursive filter, S
It is possible to improve the / N ratio and reduce noise in the video signal.

FIG. 4 is a circuit diagram showing an example of the frame recursive filter. In FIG. 4, the frame recursive filter 20 includes a coefficient control circuit 21, a frame memory 22,
It is composed of an adder 23 and multipliers 24 and 25. At a certain point in time, when the video signal is input to the frame recursive filter 20, the video signal input immediately before the current input in time series is stored in the frame memory 22.

The coefficient control circuit 21 multiplies the video signal input immediately before in time series by the filter coefficient K (0≤K≤1) in the multiplier 24. The multiplier 25 multiplies the currently input video signal by the filter coefficient (1-K). The outputs of the multiplier 24 and the multiplier 25 are added by the adder 23, and the video signal formed by the frame recursive filter 20 is output.

In the video signal output from the frame recursive filter 20, the effect of noise having no correlation between frames is reduced, and the S / N ratio is improved. Filter coefficient K
When, the theoretical S / N ratio improvement rate is 10 log
It becomes {(1 + K) / (1-K)}. That is, the larger the filter coefficient K, the better the S / N ratio.

FIG. 5 is an explanatory diagram of an example in which the frame cyclic filter of FIG. 4 is used to stabilize the display image when the image is deteriorated. The frame recursive filter is provided in the image correction circuit 12 of FIG. FIG. 5A shows the MP of FIG.
Output signal of EG video decoder 9 (signal of B), (b)
Is an input signal of a frame recursive filter provided in the image correction circuit 12 (hereinafter, the frame recursive filter is simply referred to as a filter), and (c) is an output signal of the image correction circuit 12 (C Signal, that is, the output signal of the frame recursive filter), and (d) shows the output signal of the video deterioration detection circuit 10 (the signal of D).

As shown in FIG. 5A, from the MPEG video decoder 9, the frame picture of the I picture is read as the head frame picture of the GOP and each frame of Fn-15 to Fn-30 is read. A video image in which P and B pictures are included in the
Is being output. When the reception environment deteriorates and the deterioration of the reception level is detected by the image deterioration detection circuit 10 at the timing of time ta, as shown in FIG.
The signal level of changes from L to H.

When the signal in which the deterioration of the reception level is detected by the image deterioration detection circuit 10 is input to the image correction circuit 12, the image correction circuit 12 converts each frame image into a frame image as described with reference to FIG. The I-picture frame image is controlled so as to be read out, and the I-picture frame image is input to the frame cyclic filter. As shown in FIG. 5C, in the frame cyclic filter, the filter coefficient is set to 0.0 in the normal state where the D signal level is L in FIG. There is no filtering effect on the data.

At time ta, the D signal level in FIG. 1 changes from L to H.
4 changes, the coefficient control circuit 21 of FIG. 4 sets the filter coefficient K to K> 0.0. Therefore, the input I
The picture frame image is filtered by the frame cyclic filter to improve the S / N ratio. The filter coefficient K at this time is set to be larger as the degree of deterioration of the image is larger.

As described above, in the example of FIG. 5, when the image deterioration is detected, only the I-picture frame image having a small deterioration degree is repeatedly displayed and the S / N ratio is increased by the frame cyclic filter. Is improved, it is possible to further stabilize the display image when the image is deteriorated. When the decrease in the reception level is not so large, the video correction circuit 12 reads the I-picture frame image and the P-picture frame image and inputs them to the frame cyclic filter. The frame recursive filter may be configured to filter the I-picture frame image and the P-picture frame image and output them to the image memory 13.

FIG. 6 is a block diagram showing an example using an averaging filter according to another embodiment of the present invention. Figure 6
In the above, the averaging filter 30 is provided in the image correction circuit 12, and a FIFO (First In-Firs) is provided.
t Out) first-in, first-out frame memory F
M1a to FM15a and frame memories FM1b to FM
16b. The averaging filter 30 is provided with an input side switch SWI1 for switching the input of the video data at the normal time and at the time of the video deterioration, and an output side switch SWI2 for switching the output of the video data.

The frame memories FM1a to FM15 are also provided.
Changeover switches SWA1 to SWA15 for switching input image data for a, multipliers Ma1 to Ma14 and Mb1 to Mb16, and adders A1 to A15 are provided. The multipliers Ma1 to Ma14 are the averaging filters 30.
Assuming that the number of installed stages viewed from the input side of is n, the filter coefficient K of each stage is set to K = {n / (n + 1)}. That is, the filter coefficient of the first stage multiplier Ma1 is K = 1.
/ 2, and the filter coefficient of the multiplier Ma14 at the final stage (14th stage) is K = 14/15.

Similarly, for the multipliers Mb1 to Mb15, the filter coefficient K of each stage is set to K = {1 / (n + 1)}, but the filter coefficient of the multiplier Mb16 of the final stage is K = It is set to 15/16. By thus setting the filter coefficients K of the multipliers Ma1 to Ma14 and the multipliers Mb1 to Mb15, the adders A1 to A15 are added.
The filter coefficient K of the signal added in 1 becomes 1, and the averaged signal is output. By performing the filtering by the averaging filter, the noise component of the video can be suppressed.

The input-side switch SWI1 and the output-side switch SWI2 are connected to the terminals on the white circle side in a normal state without image deterioration. In addition, frame memories FM1a to FM
Changeover switches SWA1 to SWA provided on the input side of 15a
WA15 is connected to the terminal on the white circle side. For this reason, the frame image input to the averaging filter 30 at normal time is not subjected to the filtering action and is sequentially stored in the frame memories FM1a to FM1.
M15a is transferred and output from the image correction circuit 12.

When the video deterioration detecting circuit 10 detects a decrease in the reception level, the input side switch SWI1 and the output side switch SWI2 are connected to the terminals on the black circle side. The changeover switches SWA1 to SWA15 provided on the input side of the frame memories FM1a to FM15a are also connected to the terminals on the black circle side. In such a state, the averaging filter 30
As for the video data input to, the I picture frame image alone is read by the video correction circuit 12.

I-picture frame images are sequentially framed.
Memory GO FM1b to FM16b is transferred to the first GO
When the I-picture frame image input at P is transferred to the frame memory FM16b, the I-picture frame image input at the next GOP is transmitted to the frame memory F16.
Input to M1b. Frame memory FM1b of FIG.
The FM 16b is an I picture of such two GOPs.
The frame image has been input.

The frame of the I picture transferred to the frame memories FM1b to FM16b after the reception level is lowered.
The multiplier image is multiplied by the filter coefficient K by each of the multipliers Mb1 to Mb16 and output to the adders A1 to A15. Further, before the reception level is lowered, the frame memory FM2
The frame images of I, P, and B pictures transferred to a to FM15a are multiplied by filter coefficients K by multipliers Ma1 to Ma14, respectively, and output to adders A1 to A14. The output signals of the adders A1 to A14 are input to the frame memories FM1a to FM14a. The output signal of the adder A15 is input to the frame memory FM15a.

FIG. 7 is an explanatory diagram of an example of stabilizing the display image when the image is deteriorated by using the averaging filter of FIG.
FIG. 7A shows an output signal (B signal in FIG. 1) of the MPEG video decoder 9 in FIG. 1, in which an I picture frame image is read as the head frame image of each GOP.
FIG. 7B shows the output signal of the averaging filter. FIG. 7C shows an output signal of the image correction circuit 12 (see FIG.
C signal), a normal output is obtained until the image deterioration detection circuit 10 detects a decrease in the reception level at the timing of time ta. After time ta, the output signal of the averaging filter is input to the image memory 12.

When the averaging filter of FIG. 6 is applied,
The image correction circuit 12 is not limited to the configuration in which only the I-picture frame image is read from each GOP frame image when the image is deteriorated. When the level of video deterioration is mild, instead of reading out only the I picture frame image from each frame image, the I picture frame image and the P picture frame image are read. Can be read.

FIG. 8 is a flow chart showing a processing procedure of another embodiment of the present invention. Next, this flow chart will be described. The flow chart of FIG. 8 is executed by the Mycorro computer built in the digital broadcast receiver 1 as described above, based on the configuration of the digital broadcast receiver 1 described in FIG. It is a thing.

(1) The processing program is started (step S1), and the MPEG received by the digital broadcast receiver is received.
The video signal is decoded by the MPEG video decoder into a baseband video signal (step S2). Next, it is determined whether or not the received MPEG video signal has image deterioration (step S3). When the received MPEG video signal has no image deterioration (the determination result of step S3 is NO,
In the following figures, abbreviated as N), a normal video is output (step S4).

(2) If the received MPEG video signal has image deterioration (the determination result in step S3 is YES, abbreviated as Y in the following figures), it is determined whether the image deterioration has continued for a certain period of time ( Step S5). When the image deterioration does not continue for a certain period of time (the determination result of step S5 is N), the image correction circuit corrects the image (step S5).
6) Perform image correction output processing (step S7). (3) If image degradation continues for a certain time (step S7)
If the judgment result of 5 is Y), a message is output (step S8). In this process, if the reception radio wave is cut off for a long time, the effect of image correction may not be expected, so stop the correction process and prepare in advance "Please wait for a while because the reception condition is bad". Such a message screen is displayed as an image.

[0076]

As described above, according to the present invention,
When the image deterioration due to the deterioration of the reception environment occurs, the image data is corrected by various measures according to the degree of the image deterioration. Therefore, it is possible to provide a digital broadcast receiver that allows a viewer to continuously watch a video of a digital broadcast without feeling discomfort even when the reception environment deteriorates.

[Brief description of drawings]

FIG. 1 is a block diagram showing a digital broadcast receiver according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an example of video data.

FIG. 3 is an explanatory diagram of a basic principle of the present invention.

FIG. 4 is a circuit diagram showing an example of a frame recursive filter.

5 is an explanatory diagram of an example of stabilizing a display image at the time of image deterioration using the frame cyclic filter of FIG.

FIG. 6 is a block diagram showing an example using an averaging filter.

7 is an explanatory diagram of an example of stabilizing a display image at the time of image deterioration using the averaging filter of FIG.

FIG. 8 is a flow chart showing a processing procedure of another embodiment of the present invention.
It is a chart.

[Explanation of symbols]

1 Digital broadcasting receiver 2 antenna 3 tuners 4 Digital demodulation circuit 5 Error correction circuit 6 Descrambling circuit 7-data demultiplexing circuit 8 MPEG audio decoder 9 MPEG video decoder 10 Video deterioration detection circuit 11 Memory control 12 Image correction circuit 13 Image memory 14 Speaker 15 display

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5C025 AA17 AA20 AA30 BA11 BA18                       BA25 BA30 CA09 CB07 CB10                       DA01                 5C059 KK01 MA00 MA04 MA05 PP05                       PP06 PP07 RB02 RC32 RF04                       RF21 SS02 SS30 TA18 TC21                       TD11 UA05 UA12 UA38                 5J064 AA01 BB03 BC01 BC12 BC26                       BD02                 5K028 AA01 BB04 CC05 DD01 DD02                       EE03 KK32                 5K061 AA09 BB06 BB12 CC25 DD00                       JJ07 JJ24

Claims (15)

[Claims] 1. A digital broadcast receiver that decodes a received digital broadcast wave and outputs the decoded video data to a display, detects the reception level of the received digital broadcast wave, and determines the degree of decrease in the reception level. Image correction means for correcting the image data according to the above, and output means for outputting a signal notifying the viewer that the processing for coping with the decrease in the reception level is performed. Digital broadcasting receiver that does. 2. The digital broadcast receiver according to claim 1, wherein the output means outputs a signal for notifying a viewer that the corrected image is displayed on the display. 3. The digital broadcast receiver according to claim 1, wherein the output means outputs a signal for informing a viewer that the audio of the received digital broadcast wave is temporarily interrupted. . 4. The output means outputs a signal notifying a viewer that the corrected image is displayed on the display and that the sound of the received digital broadcast wave is temporarily interrupted. The digital broadcast receiver according to claim 1, which is characterized in that. 5. The correction by the image correction means is a frame
The digital broadcast receiver according to any one of claims 1 to 4, wherein video data is formed by an intra-frame predictive coded image and a forward inter-frame predictive coded image. 6. The correction by the video correction means changes the ratio of application of the intra-frame predictive coded image and the forward inter-frame predictive coded image according to the degree of decrease in the reception level. The digital broadcasting receiver according to claim 5. 7. A digital broadcast receiver that decodes a received digital broadcast wave and outputs the decoded video data to a display, detects the reception level of the received digital broadcast wave, and determines the degree of decrease in the reception level. Video correction means for correcting video data is provided in accordance with the above, and the ratio of application of the intra-frame predictive coded image and the forward inter-frame predictive coded image is determined according to the degree of decrease in the reception level. Digital broadcast receiver characterized by changing. 8. A digital broadcast receiver that decodes a received digital broadcast wave and outputs the decoded video data to a display, detects the reception level of the received digital broadcast wave, and determines the degree of decrease in the reception level. The digital broadcast receiver is characterized by comprising video correction means for correcting the video data by removing the bidirectional inter-frame predictive coded image when is small. 9. A digital broadcast receiver that decodes a received digital broadcast wave and outputs the decoded video data to a display, detects the reception level of the received digital broadcast wave, and determines the degree of decrease in the reception level. , The bidirectional inter-frame predictive coded image and the forward frame
A digital broadcast receiver characterized by comprising video correction means for correcting video data by removing inter-frame predictive coded images. 10. A digital broadcast receiver that decodes a received digital broadcast wave and outputs the decoded video data to a display, detects the reception level of the received digital broadcast wave, and determines the degree of decrease in the reception level. Is large, a fixed message is formed without forming video data including an intra-frame predictive coded image, an inter-frame predictive coded image, and a forward inter-frame predictive coded image. A digital broadcast receiver characterized in that it outputs a signal for displaying the message on the display. 11. The correction by the image correction means is characterized in that noise is reduced by a frame recursive filter with respect to image data formed of only intra-frame predictive coded images. The digital broadcast receiver according to any one of claims 1 to 4 or claim 9. 12. The frame cyclic filter is applied to the video data formed by the intra-frame predictive coded image and the forward inter-frame predictive coded image. The noise is reduced by the method of claim 1,
9. The digital broadcast receiver according to claim 8. 13. The correction by the video correction means is performed between the frame image before the reception level is lowered and the intra-frame predictive coded image read from the video data after the reception level is lowered. 5. Noise is reduced by filtering by an averaging filter.
The digital broadcast receiver according to claim 9 or claim 10. 14. The correction by the video correction means includes a frame image before the reception level is lowered, an intra-frame predictive coded image and a forward frame which are read from the video data after the reception level is lowered. 9. The digital broadcast receiver according to claim 1, wherein noise is reduced between the inter-frame predictive coded image and the averaged filter. 15. The signal according to claim 1, wherein when the correction by the image correction means continues for a certain period of time, a signal for displaying a previously created message screen on the display is output. Digital broadcast receiver.