JPH06153116A - Voice suppression control circuit for muse vioce decoder - Google Patents

Abstract

PURPOSE:To prevent generation of unpleasant noise due to a random input after the end of a MUSE broadcast by providing a 1st voice suppression means suppressing a voice output with a control code included in each frame and a 2nd voice suppression means suppressing a voice output when a count of a frame out of synchronism pulse reaches a prescribed value to the control circuit. CONSTITUTION:A voice suppression control circuit of a MUSE voice decoder is provided with a 1st voice suppression means controlling a voice output when a voice suppression code included in each frame is detected to suppress a voice signal for a master frame period just after the broadcast of the MUSE system is finished and an input signal is at random, and also with a 2nd voice suppression means suppressing a voice output before the lapse of a frame synchronization compensation period when the count reaches a prescribed value while using a frame synchronization detection section to detect out of frame synchronism in which a counter 10 counts the pulse. Thus, generation of noise when a high definition broadcast is finished.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voice suppression control circuit of a MUSE voice decoder used in a high-definition television receiver for receiving a high-definition television signal band-compressed by the MUSE system.

[0002]

2. Description of the Related Art MUSE ((M
In a high-definition television signal (hereinafter simply referred to as "MUSE signal") band-compressed by the Ultimate Sub-Nyquist Sampling Encod-ing method, the audio signal is a differential PCM.
In this format, the video signals are multiplexed and transmitted within the vertical blanking period.

FIG. 3 is a block diagram of a conventional MUSE audio signal demodulation circuit for demodulating an audio signal multiplexed with a MUSE signal. FIG. 4 is an explanatory diagram showing the frame structure of a conventional MUSE audio bitstream.

In FIG. 3, the audio signal multiplexed with the MUSE signal input from the input terminal 1 is the A / D converter 2
Are digitally converted by. In this type of MUSE audio decoder, the intermittent signal A / D converted at the time compressed in the vertical blanking period of the video signal is transferred to the next time expansion unit 3 at 1350 kilobits / second (Kbit / S). It is converted into a continuous bit stream as a bit serial signal. The audio signal, which has been converted into a continuous signal by time extension, is processed with 1350 bits / sec as one unit (this is simply referred to as "frame"), and reinterleave processing for 25 frames is performed.

As shown in FIG. 4, the frame structure of the audio signal is such that, at the beginning of each frame, a frame synchronization pattern consisting of a 16-bit specific pattern and a 22-bit control code are added, and thereafter 1312. Bit audio data and independent data follow. The control code includes control information such as a voice mode, the number of voice channels, and voice suppression. In order to prevent an error in the transmission system, a majority decision is made in units of 36 frames (this is simply referred to as “master frame”). The determination result of this control code is applied to the audio data of the subsequent master frame period except for a part. The control code determination unit 4 determines the control code.

Further, the frame synchronization detecting section 5 generates a synchronization signal for each head of each frame, that is, for every 1 mS by detecting the frame synchronization pattern, and based on this, the subsequent processing of the DPCM demodulating section 6 is performed. Generates timing signals that control the process. Even if the frame synchronization pattern is disturbed by an error in the transmission system, the frame synchronization detection unit 5 operates by detecting the frame synchronization pattern at a predetermined position for several tens of ms by the internal counter. With this frame synchronization compensation function, C
Even if / N (carrier to noise ratio) is deteriorated, it is possible to continuously demodulate the audio signal.

As described above, the voice signal included in the bit stream is demodulated to a baseband voice signal in the DPCM demodulation unit 6 and then converted into an analog value in the D / A conversion unit 7 for voice suppression control. When the voice output is not suppressed by the unit 8, the voice is output from the output terminal 9.

In the MUSE audio decoder for demodulating the audio signal multiplexed with the MUSE signal configured as described above, the 16th bit of the control code output from the transmitting side is set immediately before the end of the MUSE broadcasting. By setting it to "1", the sound in the next master frame period is suppressed. By this function, MUSE
After the signal stops, during the frame synchronization compensation period, the synchronization state continues due to the frame synchronization compensation function, but if the frame synchronization compensation period is exceeded, it is determined that the frame synchronization is completely lost, and the voice suppression control unit 8 The output is suppressed.

Next, an example of a concrete circuit configuration of the voice suppression control section 8 will be shown.

FIG. 5 is a specific circuit configuration diagram of the voice suppression controller 8 used in the conventional MUSE voice signal demodulation circuit for demodulating a voice signal multiplexed with a MUSE signal.

In FIG. 5, when the frame synchronization pattern is not detected by the frame synchronization detection unit 5, a frame desynchronization pulse is output every one frame period, and the frame desynchronization pulse is output by the counter 10 of the voice suppression control unit 8. Counted. In addition, among the 22 bits of the control code detected by the control code detection unit 4, 1 for instructing voice suppression
If the signal of the 6th bit is "1", it is written in a memory such as a flip-flop, and the output state of "1" is continuously maintained so that the sound in the next master frame period is suppressed. In addition, the 16th bit signal instructing voice suppression becomes "0" and continues until the memory is reset (hereinafter, this signal is simply referred to as "intraframe voice suppression signal").
Note). As a matter of course, when the MUSE signal is continuously received in the normal state, the intraframe voice suppression signal is "0".

The carry output of the counter 10 and the intra-frame voice suppression signal generated by the 16th bit instructing the voice suppression of the control code are input to the 2-input OR circuit 11, and the OR circuit 11 is operated. A baseband digital audio signal output from the DPCM demodulator 6 according to the audio output suppression signal
By suppressing the baseband analog audio signal output from the D / A converter 7, the unpleasant noise output generated when the MUSE signal is stopped is suppressed.

At this time, the counter 10 is set to the set value "L" based on the frame sync compensation period by the detection signal of the frame sync pattern applied from the frame sync detector 5. The set value "L" based on the frame synchronization compensation period is set to be able to count up to several tens of frames so that the audio output can be output to the extent that the deterioration of the video output can be balanced even when the C / N is deteriorated. That is, the count value of the counter 10 remains "L" while the frame synchronization pattern is normally detected, but when the frame synchronization pattern is not continuously detected, the count value increases and becomes "L". If the frame synchronization pattern is not detected continuously during the period set by, the voice output is suppressed by the carry output output from the counter 10.

[0014]

In the MUSE audio signal demodulation circuit described above, the 16th control code sent out in advance by the transmitting side immediately before the end of the MUSE broadcasting.
The bit 1 is "1", that is, the voice output signal is temporarily suppressed by the intraframe voice suppression signal that means voice suppression, but at the end of broadcasting by the MUSE system, the control code of the control code of the frame to be received and input. The 16th bit digital signal has a random signal form that can take either "1" or "0".

At this time, due to the above-mentioned frame synchronization compensation function, even though the MUSE signal has not been input, a few tens of ms after the end of the broadcasting by the MUSE system.
The synchronization state continues during the period, and the MUSE voice signal demodulation circuit
It operates as if the USE signal was input.

Therefore, as shown in the time chart at the end of MUSE broadcasting of FIG.
That is, since 36 ms is controlled by the intra-frame voice suppression signal that means voice suppression of the control code detected in the previous master frame period, during that period, the MUSE broadcast is performed by the intra-frame voice suppression signal that means voice suppression. The voice is suppressed even after the end. However, after that, after entering the state in which the frame synchronization pattern is not detected, the counter 10 of the voice suppression control unit 8 counts the out-of-frame pulse for each frame period, and outputs the voice until the carry output occurs from the counter 10. Cannot be suppressed.

However, after the end of MUSE broadcasting, a majority decision is made by a random input signal. Therefore, after the master frame period (audio frame synchronization compensation length) has elapsed after the end of MUSE broadcasting, audio suppression is performed with a half probability. Is canceled, and unpleasant noise due to random input is generated.

Therefore, the present invention does not output an unpleasant noise due to random input after the end of the MUSE broadcasting.
It is an object to provide a voice suppression control circuit of an SE voice decoder.

[0019]

MUSE according to the present invention
The audio suppression control circuit of the audio decoder outputs the audio signal multiplexed in the video signal vertical blanking period of the MUSE signal to 1350.
Convert to a continuous bit stream of kilobits / second,
It has 1350 bits / sec as one unit frame, and further, the unit frame has a frame structure having a frame synchronization pattern, a control signal, and voice / independent data,
When the control code included in each frame indicates voice suppression, the voice output is suppressed for a predetermined first voice suppression period, and the control code included in each frame instructs voice suppression. If not, form a pulse out of frame synchronization, count it with a counter, until the predetermined count value is reached is the frame synchronization compensation period, during which,
When the loss of the frame synchronization pattern is compensated and the synchronization state is continued, and when a predetermined count value is reached, the synchronization state is released and the voice output is continuously suppressed, and the control code instructs the voice suppression. Second frame, the frame synchronization compensation period is set to be shorter than the count value for obtaining the frame synchronization compensation period, a frame desynchronization pulse is formed and counted, and when the predetermined count value is reached, the second voice suppression period for suppressing the voice output. The audio output suppression signal for suppressing the audio output is obtained by the logical sum of the first audio suppression means and the second audio suppression means.

[0020]

In the present invention, the audio signal multiplexed in the video signal vertical blanking period of the MUSE signal is converted into a continuous bit stream of 1350 kilobits / second, which is converted to 1
In a MUSE audio decoder that performs frame processing in which 350 bits / second is one unit and the unit frame is composed of a frame synchronization pattern, a control signal, and audio / independent data, among the control codes included in each frame, When the bit assigned for voice suppression indicates voice suppression, that is, immediately before the end of the broadcast by the MUSE system, from the time when the control code indicating the voice suppression transmitted by the transmission side is detected, The voice output is continuously suppressed for the first voice suppression period. At the same time, since the length of the frame synchronization compensation period is shortened, the audio output is suppressed by the control code that means the audio suppression in the master frame period immediately after the end of the broadcast by the MUSE method and the input signal becomes random. The subsequent audio output is suppressed by the loss of frame synchronization within the same period.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A speech suppression control circuit of a MUSE speech decoder according to an embodiment of the present invention will be described below.

FIG. 1 shows a voice suppression control unit 8 used in a voice suppression control circuit of a MUSE voice decoder according to an embodiment of the present invention.
FIG. 6 is a specific circuit configuration diagram of the above, and is a circuit corresponding to FIG. 5 shown in the conventional example. In addition, FIG. 2 shows an MU of an embodiment of the present invention.
FIG. 6 is a time chart at the end of MUSE broadcasting by the sound suppression control circuit of the SE sound decoder, which corresponds to FIG. 6 shown in the conventional example. It should be noted that, in the figure, the same reference numerals and symbols as those of the conventional example shown in FIG. 5 indicate the same or corresponding components as those of the conventional example. Only the configuration different from will be described.

In the embodiment shown in FIG. 1, a switching circuit 12 is added to the voice suppression control section 8 used in the voice suppression control circuit of the conventional MUSE voice decoder shown in FIG.

In the switching circuit 12, the signal of the 16th bit of the control code, which means the audio suppression sent from the transmitting side in advance immediately before the end of the MUSE broadcasting, is "0".
If so, the set value “L” based on a normal frame synchronization compensation period length, that is, a period longer than the master frame period.
Is set as an initial set value, and if the 16th bit signal of the control code that means voice suppression is “1”, the set value “S” based on a period in which the frame synchronization compensation period is shorter than the master frame period is set. , “0” of the intra-frame voice suppression signal that means voice suppression,
The initial setting value set in the counter 10 is switched by "1".

The initial setting value of the counter 10 for counting consecutive out-of-frame sync pulses in the voice suppression control section 8 is given from the switching circuit 12, but the control detected by the control code detection section 4 in FIG. While the 16th bit in-frame voice suppression signal of the 22-bit code is "0", the normal setting value "L" for obtaining the frame synchronization compensation period for compensating for the loss of the frame synchronization pattern, and ,
While the value is "1", the setting value "S" is set so that the frame synchronization compensation period for compensating for the loss of the frame synchronization pattern is set to a shorter period.

The two-input OR circuit 11 is supplied with the intra-frame voice suppression signal output from the control code detecting section 4 and the carry output of the counter 10 as in the conventional example, and the OR circuit 11 outputs voice signals. The output suppression signal is output.

In the voice suppression control circuit of the MUSE voice decoder according to the present embodiment having the above-mentioned configuration, the 16th bit of the control code sent out in advance by the transmitting side is "1" immediately before the end of the broadcast by the MUSE system. That is, the voice output signal is suppressed by the intraframe voice suppression signal that means voice suppression. The audio output is suppressed by setting the length of the next master frame period at the time when the broadcasting by the MUSE system ends as the first audio suppression period length even during the end of the broadcast, during which the audio output signal is suppressed. It

On the other hand, the voice suppression control circuit of the MUSE voice decoder of this embodiment receives the MUSE signal for a few tens of ms after the end of the broadcast by the MUSE system, though the MUSE signal is input. Works as if you are.

Therefore, as shown in the time chart at the end of MUSE broadcasting of FIG. 2, after the end of MUSE broadcasting, the state in which the frame synchronization pattern is not detected enters
The out-of-frame pulse for each frame period is counted by the counter 10 of the voice suppression controller 8. The counter 10 is M
Since the intra-frame voice suppression signal of the control code outputs the signal "1" for suppressing the voice output signal immediately before the end of the USE broadcast, the frame synchronization pattern causes the frame synchronization compensation period to be shorter than the master frame period. The set value "S" based on the shortened second voice suppression period length is used as the initial set value. Therefore, from the start of counting by the counter 10 of the voice suppression control unit 8 to the occurrence of a carry out pulse from the counter 10 of the voice suppression controller 8 based on the normal frame synchronization compensation period length. The counting time becomes shorter than that of counting with the set value "L", and a carry signal is output from the counter 10 within a short time to suppress the subsequent voice output. The time until the carry signal is output from this counter 10 is within the time when the frame synchronization compensation length is only the length of the master frame period in which the voice output signal is suppressed by the intraframe voice suppression signal which means the voice suppression. At the end of the broadcast, the audio output is suppressed by both parties.

As described above, the audio suppression control circuit of the MUSE audio decoder of this embodiment converts the audio signal multiplexed in the video signal vertical blanking period of the MUSE signal into a continuous bit stream of 1350 kilobits / second. , It 1
350 bits / sec as one unit, and the unit frame has a frame structure having a frame synchronization pattern and control signal and voice / independent data as shown in FIG. 4, and frame synchronization detection for detecting these frame synchronization patterns. Section 5 and control code detecting section 4 for detecting control signal
In the MUSE voice decoder that performs frame processing in the DPCM demodulation unit 6 that detects voice / independent data, when the control code included in each frame detected by the control code detection unit 4 indicates voice suppression, for example, , A first voice suppression means comprising the control code detection unit 4 and the voice suppression control unit 8 for continuously suppressing the voice output for a predetermined first voice suppression period such as a master frame length, and the control code detection unit 4. When the detected control code included in each frame does not instruct voice suppression, the frame synchronization detection unit 5 detects a frame out-of-frame pulse, counts it with the counter 10, and sets it to a predetermined count value in between. During the reaching frame sync compensation period, the loss of the frame sync pattern is compensated, and the loss of the frame sync pattern continues even when the predetermined count value is reached. If suppresses audio output after the frame synchronization compensation period. When the control code indicates voice suppression, the second voice suppression period is set to a period shorter than the count value of the counter 10 for obtaining the frame synchronization compensation period, and the out-of-frame synchronization pulse is detected and counted. , A second voice suppression means including a frame synchronization detection unit 5 which outputs a second voice suppression period signal when a predetermined count value is reached, a switching circuit 12 and a counter 10, the first voice suppression means and the second voice suppression means And a gate means composed of a two-input logical sum circuit 11 for making a voice output suppression signal for suppressing a voice output by a logical sum of the above.
Therefore, when the control code included in each frame detected by the control code detecting unit 4 indicates voice suppression, for example, voice output is continuously performed for a predetermined first voice suppression period such as a master frame length. The first voice suppression means including the control code detection unit 4 and the voice suppression control unit 8 for suppressing means the voice suppression of the control code detected in the previous master frame period in the unit of the master frame, that is, 36 mS. Since it is controlled by the intra-frame voice suppression signal, the voice is suppressed during that period even after the end of the MUSE broadcast by the intra-frame voice suppression signal that means voice suppression. However, after that, after entering the state in which the frame synchronization pattern is not detected, the counter 10 of the voice suppression control unit 8 counts the out-of-frame pulse for each frame period until the carry output is generated from the counter 10.
After that, the audio output cannot be suppressed.

Therefore, when the control code indicates voice suppression after the end of MUSE broadcasting, a frame synchronization compensation period shorter than the count value of the counter 10 for obtaining the master frame period (frame synchronization compensation period) is set, and frame synchronization is performed. The missed pulse is detected and counted, and when the predetermined count value is reached, the second voice suppression period is entered.
Even if a random input signal is generated after the end of E-broadcast, voice suppression is performed before the master frame period (frame synchronization compensation period length) elapses, and the generation of unpleasant noise due to random input is suppressed.

In the embodiment of the present invention, the frame sync compensation is provided in which the audio output is temporarily suppressed by the audio control code set by the transmitting side immediately before the end of the MUSE broadcasting, and at the same time, the loss of the frame sync pattern is normally compensated. Since the period length is switched to a period shorter than the frame synchronization compensation period length such as a master frame period or less, for example, within the master frame period in which the voice suppression by the voice control code immediately after the MUSE input is cut off, Random input breaks frame synchronization, and subsequent audio output is continuously suppressed.

The second voice suppression means of the above embodiment is
Although the initial setting value of the counter 10 is changed, when the present invention is carried out, the count value of the counter may be changed, or the counter may be increased or decreased. In any case, it is sufficient that the output of the counter 10 can be increased or decreased from the outside.

[0034]

As described above, the audio suppression control circuit of the MUSE audio decoder according to the present invention converts the audio signal multiplexed in the video signal vertical blanking period of the MUSE signal into a continuous bit stream of 1350 kilobits / second. It is converted into 1 unit at 1350 bits / second, and the unit frame is converted into a frame synchronization pattern, a control signal, and a voice.
In a MUSE audio decoder that performs frame processing composed of independent data, among the control codes included in each frame, the control code that means audio suppression sent by the transmitting side immediately before the end of the broadcast by the MUSE method is used. From the time of detection, the voice output is suppressed continuously for the first voice suppression period. At the same time, the frame synchronization compensation period length is shortened and the subsequent period is set as the second voice suppression period.
In the master frame period immediately after the end of the USE system broadcast and the randomization of the input signal, the voice output is suppressed only during the first voice suppression period by the control code that means the voice suppression, and the frame is generated within the same period. When the synchronization is lost, the subsequent audio output is suppressed by the second audio suppression period. Therefore, the MUSE audio decoder can suppress the generation of noise by the first audio suppression period and the second audio suppression period when the high-definition broadcast ends. Therefore, it is possible to obtain the MUSE audio decoder which does not output the unpleasant noise due to the random input after the end of the MUSE broadcasting.

[Brief description of drawings]

FIG. 1 is a specific circuit configuration diagram of a voice suppression control unit used in a voice suppression control circuit of a MUSE voice decoder according to an embodiment of the present invention.

FIG. 2 is a time chart at the end of MUSE broadcasting by the audio suppression control circuit of the MUSE audio decoder according to the embodiment of the present invention.

FIG. 3 is a block configuration diagram of a conventional MUSE audio signal demodulation circuit for demodulating an audio signal multiplexed with a MUSE signal.

FIG. 4 is an explanatory diagram showing a frame structure of a conventional MUSE audio bitstream.

FIG. 5 is a specific circuit configuration diagram of a voice suppression control unit used in a MUSE voice signal demodulation circuit for demodulating a voice signal multiplexed with a conventional MUSE signal.

FIG. 6 is a time chart at the end of MUSE broadcasting in FIG.

[Explanation of symbols]

 4 control code detection unit 5 frame synchronization detection unit 6 DPCM demodulation unit 8 voice suppression control unit 10 counter 11 OR circuit 12 switching circuit

Claims (1)

[Claims] 1. An audio signal multiplexed in a video signal vertical blanking period of a MUSE signal is converted into a continuous bit stream of 1350 kilobits / second, which is set to 1350 bits / second as one unit frame. A unit frame has a frame structure including a frame synchronization pattern, a control signal, and voice / independent data, and a frame synchronization detection unit that detects the frame synchronization pattern, a control code detection unit that detects a control signal, and demodulates the voice / independent data. In the MUSE speech decoder, when the control code included in each frame detected by the control code detection unit instructs speech suppression, a first speech suppression unit that suppresses speech output for a predetermined first speech suppression period; , The control code included in each frame detected by the control code detection unit does not indicate voice suppression. At this time, a frame out-of-frame pulse is formed, counted by the counter, and the period until the predetermined count value is reached is the frame-synchronization compensation period, during which the loss of the frame-synchronization pattern is compensated and the synchronization state is continued. Then, when the predetermined count value is reached, the synchronization state is released to suppress the audio output continuously, and when the control code instructs the audio suppression, the frame synchronization compensation period is obtained from the count value. Set to a short frame sync compensation period, form and count out-of-frame pulses,
A voice whose voice output is suppressed by a logical sum of a second voice suppressing unit that enters a second voice suppressing period that suppresses a voice output when a predetermined count value is reached, and the first voice suppressing unit and a second voice suppressing unit. An audio suppression control circuit for a MUSE audio decoder, comprising: a gate means for using an output suppression signal.