JP2002354359A - Output controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control interruption of output of an abnormal video/audio signal well. SOLUTION: A receiving signal fed to an input terminal 1 is fed to a front end section 2 and a digital signal taken out therefrom is fed to a demultiplexer section 3. A separated audio signal is decoded at an audio decoder section 4 and taken out from an output terminal 6 through an audio output control section 5. A separated video signal is decoded at an video decoder section 7 and taken out from an output terminal 9 through a video output control section 8. Furthermore, the CN value of a receiving signal determined at the front end section 2 is transmitted to a microcomputer 10 and the number of times of error occurring at the time of decoding in the video decoder section 7 is transmitted to the microcomputer 10. The microcomputer 10 forms an output interruption (mute) instruction using these values as an evaluation reference and the output interruption instruction is fed to the audio output control section 5 and the video output control section 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an output control device suitable for use in, for example, a BS (broadcast satellite) digital broadcast receiver. More specifically, for example, in receiving a BS digital broadcast transmitted by a method different from a CS (communication satellite) digital broadcast, a control for cutting off an output of an abnormal video signal and / or an audio signal due to deterioration of a received signal or the like is enhanced. It is intended to be able to perform with accuracy.

[0002]

2. Description of the Related Art For example, in CS (communication satellite) digital broadcasting, an information identification signal transmitted together with a video signal and / or an audio signal is transmitted by an equivalent modulation method. Therefore, if the received signal is deteriorated due to, for example, weather conditions, the video signal and / or the audio signal and the information identification signal are equally affected and deteriorated equally. For this reason, in the conventional CS digital broadcasting receiver, the cutoff of the output of the video signal and / or the audio signal is controlled by evaluating the state of the information identification signal.

[0003]

However, for example, BS
(Broadcast satellite) In digital broadcasting, the video signal and / or the audio signal and the information identification signal have different transfer rates, and especially when the transfer rate of the information identification signal is set low, the information identification signal is normally received. However, video / audio signals with a higher transfer rate cannot be normally received. For this reason, in a control that evaluates the state of the information identification signal as in a conventional CS digital broadcast receiver, a deteriorated video / audio signal may be displayed / output.

[0004] The present application has been made in view of such a point, and the problem to be solved is that in the conventional apparatus, for example, a video signal and / or a digital signal such as a BS (broadcast satellite) digital broadcast. When the transfer rates of the audio signal and the information identification signal are different from each other, the control of shutting off the output of the video signal and / or the audio signal could not be properly performed.

[0005]

For this reason, in the present invention, the cutoff of output is controlled using the CN value of the received signal and the error frequency when decoding the video signal and / or the audio signal as evaluation criteria. And, according to this,
The interruption of the output of the abnormal video signal and / or the audio signal can be controlled with extremely high accuracy.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS That is, in the present invention, means for receiving a digital broadcast signal transmitted including a plurality of modulation schemes, means for obtaining a CN value of the received signal, and a video signal and / or Means for decoding the audio signal and means for controlling the output of the video signal and / or the audio signal based on the CN value and the error frequency at the time of decoding are provided as evaluation criteria.

FIG. 1 is a block diagram showing the configuration of an embodiment of a main part of a receiver of, for example, a BS (broadcasting satellite) digital broadcast to which an output control device according to the present invention is applied. FIG.

In FIG. 1, an input terminal 1 is supplied with a reception signal from, for example, a broadcast satellite reception antenna (not shown). The reception signal supplied to the input terminal 1 is supplied to the front end unit 2, and a digital signal transmitted by the reception signal is extracted. The extracted digital signal is supplied to the demultiplexer unit 3, where the audio signal and the video signal are separated. Then, the separated audio signal is decoded by the audio decoder unit 4 and the audio output control unit 5
Through the output terminal 6. The video signal separated by the demultiplexer 3 is decoded by the video decoder 7 and is taken out to the output terminal 9 through the video output controller 8.

At the same time, the front end unit 2 obtains the CN value of the received signal. Note that this CN value has been conventionally obtained, for example, for adjustment at the time of mounting the antenna. Then, the CN value is compared with a reference threshold value, and the comparison result is transmitted to the microcomputer (CPU) 10. Further, for example, a result obtained by converting the number of error occurrences at the time of decoding in the video decoder unit 7 into a rate or a result obtained by comparing with a reference threshold value is transmitted to the microcomputer 10.

In the microcomputer 10, an output cutoff (mute) command is formed using these values as evaluation criteria. The formed mute command is supplied to the audio output control unit 5 and the video output control unit 8. In the audio output control unit 5 and the video output control unit 8 to which the mute command has been supplied in this manner, the control for cutting off the output of the audio signal and the video signal to the output terminals 6 and 9 is performed.

In this manner, the control for cutting off the output of the audio signal and the video signal is performed. According to the above configuration, the control for cutting off the output of the audio signal and the video signal is performed by, for example, the video decoder unit 7. Since the error rate at the time of decoding is used as an evaluation criterion, that is, control is performed by evaluating the video signal itself, control with extremely high accuracy can be performed.

In the above configuration, the CN value of the received signal is also used as an evaluation criterion. For example, if the signal has hierarchical modulation, the signal of the lower hierarchy can be displayed normally even if the CN value is low to some extent. And audio output may be possible. For this reason, in the control using only the CN value as the evaluation criterion, the display / non-display is likely to be unstable when the weather condition changes drastically. On the other hand, when there is a defect in the data of the video signal or the audio signal itself, a normal video signal or audio signal may not be obtained even if the CN value is high.

In the above-described configuration, the error rate at the time of decoding by the video decoder 7 on the output side is used as an evaluation criterion together with the CN value of the signal received by the front end section 2 on the input side, so that various conditions can be obtained. It is possible to satisfactorily perform the control for cutting off the output of the audio signal and the video signal below.

Therefore, in this embodiment, the cutoff of the output is controlled by using the CN value of the received signal and the error rate (frequency) at the time of decoding the video signal and / or the audio signal as an evaluation criterion. The interruption of the output of the video signal and / or the audio signal can be controlled with extremely high accuracy.

Thus, in the conventional apparatus, for example, B
When the transfer rates of the video signal and / or the audio signal and the information identification signal are different as in the case of S (broadcast satellite) digital broadcasting, it is possible to satisfactorily control the cutoff of the output of the video signal and / or the audio signal. According to the present invention, these problems can be easily solved.

In the above-described embodiment, the evaluation on the output side is performed only by the error rate at the time of decoding by the video decoder unit 7. However, this is because the coding of the video signal is more complicated than the coding of the audio signal. It is. However, for example, if the video signal data itself is defective, the audio signal may be normal even if the error rate of the video signal is low. May be independently evaluated and output cutoff control may be performed independently.

Further, as an evaluation criterion on the input side, a bit error rate (error rate for each bit of the data signal) detected by the front end unit 2 can be used in addition to the above-described CN value. As for this bit error rate, especially when an error correction circuit is provided, the error rate after correction is effective as a signal evaluation standard.

The measurement of the decoding error rate used as an evaluation criterion on the output side is performed, for example, by transmitting error detection data to the microcomputer 10 connected to the bus every time an error occurs and counting the error detection data on the microcomputer 10 side. Can also be determined. However, in such a method, the microcomputer 10 is interrupted every time the error detection data is transmitted.
0 has a large effect on the processing, which may lead to a hang-up or the like.

Accordingly, as described above, the number of decoding errors has been counted by the video decoder unit 7 and compared with a threshold value. When the threshold value is exceeded, an error detection is transmitted to the microcomputer 10 so that the microcomputer 1
0 can reduce the processing load and eliminate problems such as hang-ups.

Further, the above-mentioned thresholds of the CN value, the decode error rate and the bit error rate are provided with a hysteresis so as to display / hide a screen and output / non-output a sound with respect to, for example, a signal changing near the threshold. Can be suppressed, and the display of the screen and the output of the sound can be performed stably.

That is, according to the above-described embodiment, even in a broadcast in which the transfer rate of the information identification signal and the video / audio signal is different, such as a BS digital broadcast having various modulation schemes, the video itself can be evaluated by evaluating the signal itself. Audio mute control can be performed. As a determination criterion, it may not be possible to predict disturbance of video and audio of a signal after decoding, especially in the case of a modulation method having a low transfer rate, by only evaluating the CN value of an input signal. By doing so, it is possible to perform signal evaluation and optimal control of image sound mute.

Thus, according to the output control apparatus described above, means for receiving a digital broadcast signal transmitted including a plurality of modulation schemes, means for obtaining a CN value of the received signal, and a video signal and / or By providing means for decoding the audio signal and means for controlling the output of the video signal and / or the audio signal based on the CN value and the error frequency at the time of the decoding as evaluation criteria, an abnormal video signal and And / or the interruption of the output of the audio signal can be controlled with extremely high accuracy.

The present invention is not limited to the above-described embodiment, but can be variously modified without departing from the spirit of the present invention.

[0024]

According to the first aspect of the present invention, the cutoff of output is controlled based on the evaluation value based on the CN value of the received signal and the error rate (frequency) when decoding the video signal and / or the audio signal. As a result, the interruption of the output of the abnormal video signal and / or the audio signal can be controlled with extremely high accuracy.

According to the second aspect of the present invention, the accuracy of control can be improved by independently evaluating the error frequency at the time of decoding for each of the video and / or audio signals.

Further, according to the third aspect of the present invention, the evaluation frequency of the CN value and the error frequency at the time of decoding has hysteresis, thereby suppressing the frequency of switching and stabilizing the display of the screen and the output of audio. Can be performed.

According to the fourth aspect of the present invention, there is further provided a means for correcting an error of the video and / or audio signal, and an error frequency when decoding the video and / or audio signal from the error-corrected signal. By using these as evaluation criteria, control accuracy can be improved.

Thus, in the conventional device, for example, B
When the transfer rates of the video signal and / or the audio signal and the information identification signal are different as in the case of S (broadcast satellite) digital broadcasting, it is possible to satisfactorily control the cutoff of the output of the video signal and / or the audio signal. According to the present invention, these problems can be easily solved.

[Brief description of the drawings]

FIG. 1 shows an output control device according to the present invention, for example, B
It is a block diagram showing composition of one embodiment of an important section of a receiver of S (broadcasting satellite) digital broadcasting.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Input terminal, 2 ... Front end part, 3 ... Demultiplexer part, 4 ... Audio decoder part, 6 ... Audio output control part,
6 output terminal, 7 video decoder unit, 8 video output control unit, 9 output terminal, 10 microcomputer (CP
U)

Claims (4)

[Claims] 1. A means for receiving a digital broadcast signal transmitted including a plurality of modulation schemes, a means for determining a CN value of the received signal, and a means for decoding a video signal and / or an audio signal from the received signal An output control device, comprising: means for controlling output of the video signal and / or the audio signal based on the CN value and the error frequency at the time of decoding as evaluation criteria. 2. The output control device according to claim 1, wherein an error frequency at the time of decoding is independently evaluated for each of the video and / or audio signals. 3. The output control device according to claim 1, wherein an evaluation criterion for the CN value and an error frequency at the time of decoding has hysteresis. 4. An apparatus for correcting an error of the video and / or audio signal, further comprising: using an error frequency when decoding the video and / or audio signal from the signal after the error correction as an evaluation criterion. The output control device according to claim 1, wherein: