KR100264328B1 - Fade out/in compensation device and method of a digital audio - Google Patents

Abstract

PURPOSE: Adjusting device and method for fade out/in of a digital audio are provided to efficiently suppress a discontinuous sound generated when converting modes. CONSTITUTION: An audio stream is inputted and is decoded. A right shift bit number is reduced at an end of a mode convert section. An edge detect clock of a high state is detected in a rising edge and a falling edge of a left/right channel clock. The serial audio stream is synchronized to the edge detect clock for converting into parallel audio data. After detecting a start of a mode switching section, an upper right shift operation is performed to detect an end of the mode switching section. Then, the shift bit number is reduced for being identified with a minimum shift bit number. The parallel shifted audio data are synchronized to the edge detect clock to be converted into serial data stream.

Description

Fade out / in controls and methods of digital audio

TECHNICAL FIELD The present invention relates to an apparatus and a method for adjusting a fade out / in of digital audio, and more particularly, to at least two or more digital audio formats. In the mode switching section in which the mode switching between different digital audio formats is performed when the audio stream is input and played, a fade out / in adjustment function is implemented by a shift operation to effectively suppress the occurrence of discontinuous sound generated during the mode switching. The present invention relates to a fade out / in control apparatus and method for digital audio.

Today, media playback media such as Digital Video Disk Player (DVDP), Laser Disk Player (LDP), Compact Disc ROM Driver, Hard Disk Driver, Tape Driver, etc. Thanks to the rapid development of technology and popular dissemination under low-cost policies, many software / hardware results are created.

Storage media that can be played back through such media playback media (ie, tapes, magnetic disks, compact disks, hard disks, laser disks, digital video disks, etc.) are recorded based on a number of digital audio formats. This mixture is common.

In this case, discontinuous sounds such as noise and transients frequently occur during mode switching in the mode switching section in which mode switching between different digital audio formats is performed when the audio stream recorded on the storage medium is played back. The most common method used to remove or suppress discontinuous sounds is to stop the playback of the audio stream and mute the played audio in the mode switching section.

1 is a block diagram showing a general audio / video decoding apparatus.

As shown in FIG. 1, a general audio / video decoding apparatus includes a video signal path 10 and an audio signal path 20. The video signal path 10 includes a video decoder 11 and a digital analogue. The audio signal path 20 is composed of an audio decoder 21, a digital analog converter 22, and an S / P DIF transmitter (Sony / Philips Digital InterFace Transmitter) 23. It decodes the input audio / video stream and outputs the signal to the analog or digital output terminal.

To describe the operation of the above configuration in detail, the input audio / video stream is divided into a video signal and an audio signal, and the video signal is input to the video signal processor 10.

At this time, the MPEG-1 (Motion Picture Experts Group-1) or MPEG-1 (Motion Picture Experts Group-1) video decoder is used, and the reconstructed digital video signal is input to the digital-analog converter 12 and converted into an analog signal. do.

In addition, the separated audio signal of the audio / video stream is input to the audio signal processing unit 20 and expanded to the signal before compression through the audio decoding unit 21. In the case of a normal DVDP, MPEG, AC-3 or Since three modes of linear PCM (linear pulse code modulation) are used, they are extended appropriately for each mode according to the type of stream, and the restored audio signal is converted to analog through the digital-to-analog converter 22 for audio. The digital signal is converted and output or is output as a digital signal based on a digital interface format through the S / P DIF transmission unit 23.

As described above, the audio / video decoding apparatus includes a microcomputer (not shown) in a mode switching section in which mode switching between different digital audio formats is performed to remove or suppress discontinuous sounds generated during the mode switching process. The audio mute control signal is applied by the controller to cancel or stop the output of the digital-to-analog converter and the output of the S / P DIF transmitter to cause loss of reproduction sound before and after the mode switching section, and another form of mode switching noise. There is a problem that is likely to occur.

In particular, due to unnatural mode switching due to sudden mute processing has been a cause of surprise or discomfort to the listeners listening to this, causing a lowering of the satisfaction or confidence of the product.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and mode switching in which mode switching between different digital audio formats is performed when an audio stream including at least two digital audio formats is received and played back is performed. It is an object of the present invention to provide an apparatus and method for adjusting fade out / in of digital audio that can effectively suppress generation of discontinuous sound generated during mode switching by implementing a fade out / in adjustment function by shift operation in a section.

1 is a block diagram showing a general audio / video decoding apparatus.

2 is a block diagram showing a preferred embodiment of the fade out / in adjustment apparatus of digital audio according to the present invention.

3 is a block diagram showing a preferred embodiment of the fade adjustment unit of the present invention.

4 is a timing diagram showing the output of each main portion of the fade adjustment unit of the present invention.

5 is an exemplary diagram showing a state in which a shift bit number of the shift calculation control unit is increased or decreased.

Figure 6 shows a flowchart of a preferred embodiment of the method for adjusting the fade out / in of digital audio according to the present invention.

* Explanation of symbols for main parts of the drawings

21: audio decoder 22: analog-to-digital converter

23: S / P DIF transmitter 100: fade adjustment unit

110: edge detection circuit portion 120: series parallel conversion portion

130: right shift calculation unit 140: shift calculation control unit

150: parallel serial converter

Thus, the present invention for achieving the object receives an audio stream including at least two digital audio formats (digital audio format) is decoded into each digital audio format, receiving a decoded audio stream is a different digital audio format Fade out / in by incrementally increasing the number of shift bits of the right shift operation at the beginning of the mode switching interval in which the mode switching is performed, and gradually reducing the number of shift bits of the right shift operation at the end of the mode switching interval. It is characterized by performing an adjustment function.

Hereinafter, the configuration and operation of a preferred embodiment of the fade out / in adjustment apparatus for digital audio according to the present invention will be described with reference to FIG.

2 is a block diagram showing a preferred embodiment of the fade out / in adjustment apparatus of digital audio according to the present invention.

As shown in FIG. 2, a preferred embodiment of an apparatus for adjusting fade out / in of digital audio according to the present invention includes an audio decoder 21 for receiving an audio bit stream separated from an audio / video stream. Configure.

The audio decoder 21 receives an audio stream including at least two digital audio formats and decodes each digital audio format.

Thereafter, the fade adjuster 100 receives the output of the audio decoder 21 to determine the number of shift bits of the right shift operation at the start of the mode switching section in which mode switching between different digital audio formats is performed. A fade out / in adjustment function is performed by incrementally increasing and gradually decreasing the number of shift bits of the right shift operation at the end point of the mode switching interval.

In other words, incrementally increasing the number of shift bits for the right shift operation is for performing a fade out function, and decreasing the number of shift bits in steps is for performing a fade in function. According to this, it is possible to implement natural mode switching.

Thereafter, the analog-to-digital converter 22 receives the output of the fade adjuster 100 and outputs the digital-to-analog converter, and the S / P DIF transmitter 23 is an S / P DIF (Sony / Philips Digital Interface) format. To digital output.

3 is a block diagram showing a preferred embodiment of the fade adjustment unit 100 of the present invention.

As shown in FIG. 3, the fade adjuster 100 of the present invention has a rising edge of a left / right channel clock generated from an external clock device to synchronize the left channel and the right channel, respectively. Edge detection circuitry 110 for generating a high state edge detection clock at the falling edge; A serial parallel converter 120 for converting the serial audio stream input from the audio decoder 21 into parallel audio data units of a predetermined length in synchronization with the edge detection clock; A right shift operation unit 130 for performing right shift operation on the left / right channel clock units of the one cycle by the number of shift bits inputted from the serial-parallel converter 120 in synchronization with the edge detection clock; Upon detecting the mode switching signal applied to the start point of the mode switching section, the shift bit number is increased in steps until the maximum shift bit number is set in synchronization with the edge detection clock, and the end point of the mode switching section is increased. A shift operation control unit (140) which gradually reduces the number of shift bits set to the maximum number of shift bits until it is equal to a predetermined number of cancel shift bits as it is detected; And a parallel serial converter 150 for converting the parallel audio data shifted by the right shift calculator 130 into a serial data stream in synchronization with the edge detection clock.

Referring to the operation of the fade adjustment unit 100 of the present invention configured as described above, first, the edge detection circuit unit 110 is a positive clock (that is, high on the falling and rising edges of the edge detection clock generated from an external clock generator). And the edge detection clock generated in this manner synchronizes the serial parallel converter 120, the shift operation controller 140, and the parallel serial converter 150.

The serial parallel converter 120 converts the serial audio stream inputted from the audio decoder 21 into the parallel audio data unit having a predetermined length in synchronization with the edge detection clock generated from the edge detection circuit 110 and converts the right audio shift unit into a predetermined length. 130 outputs the parallel audio data inputted from the serial-parallel converter 120 by performing a right shift operation in units of the left / right channel clocks of the period as many as the number of shift bits.

The shift operation control unit 140 generates the number of shift bits as the mode switching signal input from the outside is synchronized with the edge detection clock generated from the edge detection circuit unit 110, and the right shift operation unit 130 converts the serial-parallel conversion. The parallel audio data received from the unit 110 is shifted right by the number of shift bits generated by the shift operation control unit 140, and the parallel-serial conversion unit 150 synchronizes with the edge detection clock generated from the edge detection circuit unit 110. Then, the right shift operation unit 130 receives the right shifted parallel audio data, converts it into a serial data stream, and outputs it to the digital-to-analog converter 22 and the S / P DIF transmitter 23.

4 is a timing diagram showing the output of each main part of the fade adjustment unit 100 of the present invention.

FIG. 4 (a) shows a left / right channel clock generated from an external clock device for synchronizing the left channel and the right channel, respectively. FIG. 4 (b) shows the left / right channel clock. 4 (c) is a data stream input from the audio decoder 21, and FIG. 4 (d) shows the input data stream in series and parallel. The parallel audio data, which is a parallel signal converted by the converter 120, is a signal in which the parallel audio data is right shifted by the right shift calculator 130, and the fourth (f) is a parallel serial conversion. A serial data stream restored by section 150 is shown.

Here, the shift operation control unit 140 detects the mode switching signal applied to the start point of the mode switching interval, and incrementally shifts the shift bit number until it is equal to a preset maximum shift bit number in synchronization with the edge detection clock. As the end point of the mode switching section is increased, the number of shift bits set to the maximum number of shift bits is gradually decreased and inputted to the right shift calculator until the minimum shift bit number is equal to a preset minimum number of shift bits.

At this time, the maximum number of shift bits and the minimum number of shift bits are preferably the number of bits and zero bits of the parallel audio data, respectively. FIG. 5 shows an example in which the number of bits of the parallel audio data is 16 bits.

5 is an exemplary diagram illustrating a state in which the shift bit number of the shift operation control unit 140 increases or decreases.

When the mode switching signal is input from the outside to the shift operation control unit 140 at the start of the mode switching period, the shift operation control unit 140 increases the number of shift bits increased by 1 bit for each period of the left / right channel clock. After increasing, the state is maintained until the end point of the mode switching section is detected.

That is, the right shift operator 130 that receives the right shift operation and performs the right shift operation as the shift bit number for the right shift operation increases from 0 to 16 for 16-bit parallel audio data is consequently increased. The fade out function is performed, and the mute process is performed to the end point of the mode switching section in the state shifted right by 16 bits.

Thereafter, after the end point of the mode switching interval is detected, that is, after the mode switching is performed, the shift operation control unit 140 sets the number of shift bits set to 16 bits by one bit for each period of the left and right channel clocks. It decreases until it is inputted to the right shift calculator 130.

That is, as the number of shift bits for the right shift operation is reduced step by step from 16 to 0 for 16-bit parallel audio data, the right shift operation unit 130 receiving the right shift operation and performing the right shift operation is performed. As a result, fade in is possible, and a 0-bit right shift operation means that audio data is normally played back as it is the same as stopping the shift operation.

Hereinafter, a preferred embodiment of the fade out / in adjustment method of digital audio according to the present invention will be described with reference to FIG.

Figure 6 shows a flowchart of a preferred embodiment of the method for adjusting the fade out / in of digital audio according to the present invention.

According to a preferred embodiment of the method for adjusting fade out / in of digital audio according to the present invention, as shown in FIG. 6, an audio stream including at least two or more digital audio formats is input to each digital digital audio format. An audio decoding step S100 of decoding to an audio format is performed.

Then, in the fade adjustment step (S200), the shift bit number of the right shift operation is gradually increased at the start of the mode switching section in which the mode switching between different digital audio formats is performed by receiving the audio stream, The fade out / in adjustment function is performed by gradually decreasing the number of shift bits of the right shift operation at the end point.

Subsequently, the analog-to-digital conversion step (S110) receives the right shifted audio stream and outputs the digital analog conversion, and in the S / P DIF transmission step (S120), the S / P DIF (Sony / Philips Digital Interface) format is converted. To output the digital output.

Hereinafter, the fade adjustment step (S200) will be described in detail.

As shown in FIG. 5, the fade adjustment step S200 may include a rising edge and a falling edge of a left / right channel clock for synchronizing the left channel and the right channel, respectively. At the edge), an edge detection step S210 for generating an edge detection clock in a high state is performed.

In the serial-to-parallel conversion step (S220), the audio stream serially input is converted into parallel audio data units having a predetermined length in synchronization with the edge detection clock.

Thereafter, in the mode switching start point detection step (S230), the starting point of the mode switching section in which the mode switching between different digital audio formats is performed is detected.

When the start point of the mode switching interval is detected, in the up-right shift operation step (S240), the one shift of the one cycle until the number of shift bits is equal to a preset maximum number of shift bits for the parallel audio data in synchronization with the edge detection clock. Up-right shift operation in left / right channel clock unit.

Thereafter, the mode switching end point detection step (S250) detects the end point of the mode switching section.

When the end point of the mode switching interval is detected, in the downward right shift calculation step (S260), the maximum shift bit number is set to be synchronized with the edge detection clock until it is equal to the minimum shift bit number preset for the parallel audio data. The number of shift bits is decreased stepwise to perform the down-right shift operation in units of the left and right channel clock units of one period.

Here, the maximum number of shift bits and the minimum number of shift bits are preferably the number of bits and zero of the parallel audio data, respectively, and the number of bits of the parallel audio data is preferably 16.

In the parallel serial conversion step (S270), the shifted parallel audio data is converted into a serial data stream in synchronization with the edge detection clock.

Terminologies used herein are terms defined in consideration of functions in the present invention, which may vary according to the intention or customs of those skilled in the art, and the definitions should be made based on the contents throughout the present application. will be.

In addition, since the present invention has been described through the preferred embodiment of the present invention, in view of the technical difficulty aspects of the present invention, those having ordinary skill in the art can easily be different from another embodiment of the present invention. Since modifications may be made, it is obvious that both the embodiments and modifications cited in the above description belong to the claims of the present invention.

As described in detail above, an audio stream including at least two digital audio formats is received and decoded into respective digital audio formats, and a decoded audio stream is received between different digital audio formats. Fade out / in adjustment by incrementally increasing the number of shift bits of the right shift operation at the beginning of the mode switching interval in which the mode switching is performed, and gradually reducing the number of shift bits of the right shift operation at the end of the mode switching interval. According to the apparatus and method for fade out / in of digital audio characterized in that the function is performed, there is an advantage that the generation of discontinuous sound occurring at the time of mode switching can be effectively suppressed.

Claims (10)

An audio decoder which receives an audio stream including at least two digital audio formats and decodes each of the digital audio formats; And incrementally shifting the number of shift bits of the right shift operation at a start point of a mode switching section in which mode switching between different digital audio formats is performed by receiving the output of the audio decoder, and performing a right shift operation at an end point of the mode switching section. And a fade adjuster for performing a fade out / in adjustment function by gradually reducing the number of shift bits, wherein the fade adjuster includes left and right channels generated from an external clock device to synchronize left and right channels, respectively. An edge detection circuit unit for detecting an edge detection clock in a high state at rising and falling edges of a left / right channel clock; A serial parallel converter for converting the serial audio stream input from the audio decoder into a parallel audio data unit having a predetermined length in synchronization with the edge detection clock; A right shift calculator configured to right shift the parallel audio data inputted from the serial-parallel converter by a predetermined period in synchronism with the edge detection clock; Upon detecting the mode switching signal applied to the start point of the mode switching section, the shift bit number is increased in steps until the maximum number of shift bits is equal to the preset maximum shift bit in synchronization with the edge detection clock, and ends of the mode switching section. A shift operation control unit which sequentially decreases the number of shift bits set to the maximum number of shift bits and inputs them to the right shift operation unit until detecting a predetermined minimum number of shift bits; And a parallel serial converter for converting the parallel audio data shifted by the right shift operator into a serial data stream in synchronization with the edge detection clock. 2. The apparatus of claim 1, further comprising: an analog-digital converter configured to receive an output of the fade adjustment unit and convert the digital-to-analog converter and output the digital-to-analog converter; And an S / P DIF transmitter configured to receive an output of the fade adjuster and convert the S / P DIF (Sony / Philips Digital Interface) format to output digital output. Device. The apparatus of claim 2, wherein the maximum number of shift bits is the number of bits of the parallel audio data. 4. The apparatus as claimed in claim 3, wherein the predetermined period unit is one period unit of the left / right channel clock. The apparatus of claim 3, wherein the number of bits of the parallel audio data is 16. The apparatus of claim 2, wherein the minimum number of shift bits is zero. An audio decoding step of receiving an audio stream including at least two digital audio formats and decoding them into respective digital audio formats; And incrementally shifting the number of shift bits of the right shift operation at a start point of a mode switching section in which mode switching between different digital audio formats is performed by receiving the audio stream, and shift bits of a right shift operation at an end point of the mode switching section. A fade adjustment step of performing a fade out / in adjustment function by decreasing the number step by step, wherein the fade adjustment step comprises: a left / right channel clock for synchronizing the left channel and the right channel, respectively; an edge detection step of detecting an edge detection clock in a high state at a rising edge and a falling edge of a clock; A serial parallel conversion step of converting the serially input audio streams into parallel audio data units of a predetermined length in synchronization with the edge detection clock; A mode switching start point detecting step of detecting a starting point of a mode switching section in which mode switching between the different digital audio formats is performed; When the start point of the mode switching section is detected, the up-right shift operation is performed in the upward-right shift operation in predetermined cycle units until the number of shift bits is equal to a preset maximum shift bit number for the parallel audio data in synchronization with the edge detection clock. Operation step; A mode switching end point detection step of detecting an end point of the mode switching section; When the end point of the mode switching section is detected, the number of shift bits set to the maximum number of shift bits is gradually reduced by synchronizing with the edge detection clock until the minimum number of shift bits is set for the parallel audio data. A down right shift calculation step of performing a down right shift operation on the basis of the predetermined period; And a parallel serial conversion step of converting the shifted parallel audio data into a serial data stream in synchronization with the edge detection clock. 8. The method of claim 7, further comprising: an analog-digital conversion step of receiving the right shifted audio stream and performing digital-to-analog conversion; And a S / P DIF transmission step of receiving the right shifted audio stream and converting the S / P DIF (Sony / Philips Digital Interface) format to output a digital output. How to adjust / in. The method of claim 8, wherein the maximum number of shift bits is a number of bits of the parallel audio data. The method of claim 8, wherein the predetermined period unit is one period unit of the left and right channel clocks.

Images