KR100211752B1 - Audio muting circuit of digital audio amplifier - Google Patents

Abstract

end. TECHNICAL FIELD OF THE INVENTION

This is a technology that mutes the audio signal output when AC-3 data is detected during audio data playback in a digital audio amplifier.

I. Technical Problems to be Solved by the Invention

To reproduce PCM audio signals reproduced from a DVD in a general digital audio amplifier, when an AC-3 data is converted to an analog signal in a general digital audio amplifier and strange sound is produced, an audio player -3 Mute the audio data.

All. The point of the solution of the invention

When the AC-3 data is detected while the bitstream audio data reproduced from the DVD is converted into the analog signal and reproduced in the general digital audio amplifier, the audio data converted into the analog signal is muted so as not to be output.

la. Important Uses of the Invention

Applies to audio mute circuit of digital audio amplifier.

Description

AUDIO MUTING CIRCUIT OF DIGITAL AUDIO AMPLIFIER [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an audio muting circuit in an amplifier of a digital audio system, and more particularly to a circuit for inputting bit stream data and for muting an audio signal upon detection of AC-3 data.

A typical DVD system modulates AC-3 data or PCM data picked up from a disc, converts it into a Sony / Philips digital interface format (S / P DIF) and outputs it through a fiber optic cable or a coaxial cable. The input data is converted from a digital audio amplifier to an analog signal, amplified, and output to a speaker.

1 is a circuit diagram of a conventional digital audio amplifier.

The digital interface receiver 10 restores the bitstream data converted into the Sony / Philips digital interface format into PCM data stored in the original disk and outputs the data. The digital filter 12 digitally filters and outputs the restored PCM data. The digital / analog converter (D / A converter) 14 can be realized by a PCM1710 manufactured and sold by BURRBRAWN, USA, and converts the digital filtered PCM data into an analog signal and outputs the analog signal. The analog filter 16 filters the PCM data converted into the analog signal and outputs it to a speaker or the like. The amplifying unit 18 amplifies the analog signal filtered from the analog filter 16 to a predetermined level, and outputs the amplified analog signal to the speaker.

As shown in FIG. 1, the conventional digital audio amplifier reproduces the PCM audio signal reproduced from the DVD. When the AC-3 data is converted into the analog signal in the general digital audio amplifier and reproduced, an unusual sound is produced. There was a problem.

It is therefore an object of the present invention to provide a circuit for muting an audio output when AC-3 data is detected in a digital audio amplifier.

According to an aspect of the present invention, there is provided a digital audio system including a digital interface receiver for recovering and outputting bitstream data converted into a Sony / Philips Digital Interface format into data stored in an original disk, And a digital-to-analog converter for converting the digitally filtered data into an analog signal and outputting the bit-stream data converted by the Sony / Philips digital interface format, An AC-3 data detecting unit for detecting data and outputting an audio mute signal, and an audio mute unit for muting the analog-converted AC-3 data output from the D / A converter by the audio mute signal .

1 is a circuit diagram of a conventional digital audio amplifier

2 is a circuit diagram of a digital audio amplifier according to an embodiment of the present invention.

Fig. 3 is a circuit diagram of the AC-3 detection circuit of Fig. 2 according to the embodiment of the present invention

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a circuit diagram of a digital audio amplifier according to an embodiment of the present invention.

The digital interface receiver 20 restores the bitstream data converted into the Sony / Philips digital interface format into PCM data stored in the original disk and outputs the PCM data. The digital filter 24 digitally filters and outputs the restored PCM data. The digital-to-analog converter (D / A converter) 26 can be realized by a PCM1710 manufactured and sold by BURRBRAWN, USA, and converts the digital filtered PCM data into an analog signal and outputs the analog signal. The analog filter 26 filters the PCM data converted into the analog signal and outputs the filtered data to a speaker or the like. The amplifying unit 28 amplifies the analog signal filtered from the analog filter 28 to a predetermined level and outputs the amplified analog signal to the speaker. The AC-3 data detection circuit 22 receives the bitstream data to discriminate AC-3 data and outputs an audio mute signal. The audio mute unit 30 includes a resistor R1 and a transistor Q1 to mute the analog-converted AC-3 data output from the D / A converter 26. [

3 is a specific circuit diagram of the AC-3 detection circuit of FIG. 2 according to an embodiment of the present invention.

The serial-to-parallel converter 42 converts serial bit stream data input according to a bit clock into 16-bit parallel data when the bit stream data reproduced from the disc is input in synchronism with a word clock Output. The synchronous signal generating unit 44 is composed of a 10-bit counter, and counts a word clock to generate a first data synchronizing signal of each frame. The reference value setting unit 48 has a reference value for determining the AC-3 signal. The comparator 46 is enabled by the synchronization signal output from the synchronization signal generator 44 and outputs the bitstream data converted from the serial-to-parallel converter 42 to the parallel data from the reference value setting unit 48 The AC-3 signal is compared with the reference set value to output a data selection signal.

The operation of the preferred embodiment of the present invention will be described in detail with reference to FIG. 2 to FIG.

The digital interface receiver 20 restores the bitstream data converted into the Sony / Philips digital interface format into PCM data stored in the original disk and outputs the PCM data. The digital filter 24 digitally filters and outputs the restored PCM data. The digital / analog converter (D / A converter) 26 is implemented as a PCM1710 manufactured and sold by BURRBRAWN, USA, and converts the digital filtered PCM data into an analog signal and outputs the analog signal. The analog filter 28 filters the PCM data converted into the analog signal and outputs it to a speaker or the like. The amplifying unit 32 amplifies the analog signal filtered from the analog filter 28 to a predetermined level and outputs the amplified analog signal to the speaker. At this time, the AC-3 data detection circuit 22 detects the AC-3 data by inputting bitstream data and outputs an audio muting signal. The concrete operation of detecting AC-3 data in the AC-3 data detection circuit 22 and outputting an audio muting signal will be described with reference to FIG.

The serial-to-parallel converter 42 converts the serial bit stream data input according to the bit clock when the bit stream data reproduced from the disc is input in synchronism with the word clock, into 16-bit parallel data. At this time, the synchronization signal generator 44 is composed of a 10-bit counter and counts a word clock to generate a synchronization signal of the first data of each frame. For example, when the bitstream data is 384 Kbps, the sync signal generator 44 is a 768 ring counter that counts up to 768 and is reset to 0 again because one frame is 768 words. The reference value setting unit 48 has a reference value of 0B77 which is a hexadecimal value for judging the AC-3 signal. Accordingly, the comparator 46 compares the bitstream data, which is enabled by the synchronization signal output from the synchronization signal generator 44 and converted into parallel data from the serial-to-parallel converter 42, with the reference set value of 0B77 Thereby discriminating the AC-3 signal and outputting a data selection signal. At this time, the comparator 46 detects AC-3 data and outputs a logic high signal if the bitstream data matches 0B77, and outputs a logic low signal if the bitstream data does not match 0B77. When AC-3 data is detected from the comparator 46 and a high signal is output, the transistor Q1 is turned on to pass the converted analog signal from the D / A converter 26 to ground, The audio signal output to the speaker is interrupted.

In the embodiment of the present invention, when the AC-3 data is detected, the audio signal converted into the analog signal from the D / A converter 26 is muted by the audio muting unit 30, The AC-3 signal is supplied to the speaker 22 through the analog filter 28 and the amplification unit 32. The AC / 3 signal is supplied to the D / A converter 26, As shown in FIG.

As described above, according to the present invention, an audio signal output when AC-3 data is detected from bitstream data input from a digital audio amplifier is blocked, so that an abnormal sound other than an audio signal due to AC- There is an advantage to be able to do.

Claims (5)

In a digital audio system, A digital interface receiver for restoring bitstream data converted into a Sony / Philips digital interface format into data of a type stored in an original disk and outputting the bitstream data, A digital filter for digitally filtering the restored data and outputting the restored data; A digital / analog converter for converting the digitally filtered data into an analog signal and outputting the analog signal, An AC-3 data detector for inputting bitstream data converted into the Sony / Philips digital interface format to discriminate AC-3 data and output an audio mute signal; And an audio mute unit for mute the analog-converted AC-3 data output from the D / A converter by the audio mute signal. The apparatus of claim 2, wherein the AC-3 data detection circuit comprises: A serial-to-parallel converter for converting serial bit stream data input according to a bit clock when the bit stream data is input in synchronization with a word clock, into parallel data; A synchronization signal generator for counting a word clock to generate a synchronization signal at the first data of each frame, And a comparator which is enabled by the synchronizing signal outputted from the synchronizing signal generating unit and outputs the audio mute signal by detecting the AC-3 signal by comparing the bit stream data converted from the serial- And the audio mute circuit of the digital audio amplifier. The method of claim 3, Wherein the sync signal generating unit comprises a 10-bit counter. 5. The method of claim 4, Wherein the set reference value is 0B77. In a digital audio system, A digital interface receiver for restoring bitstream data converted into a Sony / Philips digital interface format into data of a type stored in an original disk and outputting the bitstream data, A digital filter for digitally filtering the restored data and outputting the restored data; A digital / analog converter for converting the digital filtered data into an analog signal and outputting the analog signal, and stopping the analog conversion operation when the audio mute signal is input; And an AC-3 data detector for inputting bitstream data converted into the Sony / Philips Digital Interface format to discriminate AC-3 data and output an audio mute signal to the digital / analog converter. Audio mute circuit.