KR101512842B1 - A Digital Audio Transport System - Google Patents

Abstract

The present invention relates to a digital audio transmission system. The digital audio transmission system according to the present invention changes the coding method between the core codecs according to different coding schemes according to whether the input sound source is a voice or an audio signal and detailed characteristics of the sound source, A sound source coder for performing coding;
A framing unit for receiving stream data coded and inputted from the sound source coder and detecting specific data for coding to generate a transmission frame including a header and a protection code of the header and outputting the transmission data; Transmission error coding means for performing a procedure including transmission error coding for a transmission frame formed by the framing means; And transmission data generation means for generating and outputting at least one transmission frame in which the transmission error coding is completed by dividing the transmission frame into a predetermined number of logical DAB frames.

Description

[0001] A Digital Audio Transport System [

The present invention relates to a digital audio transmission system, and more particularly, to a digital audio transmission system, in which a coding method is changed in real time according to the characteristics of a sound source, and optimized sound source coding is performed and transmitted. Quality digital audio transmission system.

Conventional digital audio services have evolved independently in different service areas, such as a speech encoding technique based on a human speech generation model and a respective audio encoding technology based on a human auditory model.

For example, AMR-WB + has recently been proposed as a technology for voice coding technology, centering on voice communication. However, as shown in FIG. 1, AMR-WB + can provide a high-quality service for a sound source corresponding to a human voice, but the quality of the audio signal deviating from the AMR-WB + region tends to be lowered.

On the other hand, HE-AAC v2 technology has been proposed following the MPEG-1 Layer ∥ used for providing digital music broadcasting, but HE-AAC v2 is a high quality service But the service quality tends to be lower for the voice domain.

Recently, a convergent audio coding method capable of providing a high quality service for both a voice domain and a general audio signal has been proposed in accordance with a tendency that a conventional audio communication and a music broadcast are integrated.

It is an object of the present invention to provide a digital audio transmission method and a digital audio transmission method capable of providing an excellent quality for both audio and audio by performing an optimized sound source coding and modifying a coding method in real time according to the characteristics of the sound source, System.

It is another object of the present invention to provide a method and an apparatus for modifying a coding method according to characteristics of an input sound source and performing optimized sound source coding and transmission to thereby provide superior quality for both voice and audio, Digital audio transmission system.

According to another aspect of the present invention, there is provided a digital audio transmission system including a core codec according to different coding schemes according to whether a voice source is an audio or an audio signal, A sound source coder for performing optimized sound source coding; (K) source frames (ACCESS UNITs) constitute one transmission frame (hereinafter referred to as a super frame), or K pieces of sound sources Frame generation means for generating and outputting a transmission frame such that each frame comprises a plurality of transmission frames, each transmission frame including a header and a protection code of the header; Transmission error coding means for performing a procedure including transmission error coding for generating an error correction code by a turbo code or an LDPC code for a transmission frame formed by the framing means; And transmission data generation means for generating and outputting at least one transmission frame in which the transmission error coding is completed by dividing the transmission frame into a predetermined number of logical DAB frames.

According to another aspect of the present invention, there is provided a digital audio transmission system including a core codec according to different coding schemes according to whether a voice source is an audio or an audio signal, A sound source coder for performing optimized sound source coding; (K) source frames (ACCESS UNITs) constitute one transmission frame (hereinafter referred to as a super frame), or K pieces of sound sources Frame generation means for generating and outputting a transmission frame such that each frame comprises a plurality of transmission frames, each transmission frame including a header and a protection code of the header; Transmission error coding means for performing a procedure including transmission error coding for generating an error correction code by a turbo code or an LDPC code for a transmission frame formed by the framing means; Transmission data generating means for generating and outputting at least one transmission frame in which the transmission error coding is completed by dividing the transmission frame into a predetermined number of logical DAB frames; And multiplexing means for receiving the output of the transmission data generating means and multiplexing the data together with the data including the signaling data and the service information data corresponding thereto.
According to another aspect of the present invention, there is provided a digital audio transmission system including a core codec according to different coding schemes according to whether a voice source is an audio or an audio signal, A sound source coder for performing optimized sound source coding; (K) source frames (ACCESS UNITs) constitute one transmission frame (hereinafter referred to as a super frame), or K pieces of sound sources Frame generation means for generating and outputting a transmission frame such that each frame comprises a plurality of transmission frames, each transmission frame including a header and a protection code of the header; Transmission error coding means for performing a procedure including transmission error coding for generating an error correction code for a transmission frame formed by the framing means; And generating and outputting at least one transmission frame in which the transmission error coding is completed to a predetermined number of logical DAB frames, and outputting the error correction code for each logical DAB frame. system. And the transmission error coding performed by the transmission error coding means generates an error correction code based on the turbo code.

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And the transmission error coding means further performs a vertical data interleaving process before or after the transmission error coding.

The multiplexing unit may further include at least one of the other service type transmission data, DAB transmission data, DAB + transmission data, and data broadcasting data to perform multiplexing.

The signaling data has the same configuration as the signaling data of the DAB transmission system and different values of the audio service component type are given.

Characterized in that the logical DAB frame further comprises an error correction code for each.

And the protection code of the header is an LDPC code.

According to the present invention, by changing the coding method in real time according to the characteristics of a sound source and performing transmission / reception of optimized sound source coding on the input sound source, It becomes possible to provide quality.

In particular, since turbo code coding is applied to a transmission frame, a strong error correction function can be given to the audio transmission data, which requires a complicated header information for sound source decoding and a relatively small amount of transmission data, And the like.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a chart comparing the quality of audio service provision for a sound source frame coded by a conventional AMR-WB + and HE-AACv2 coding method.
2 is a schematic diagram illustrating a digital audio transmission system in an embodiment of the present invention;
3 is a schematic diagram illustrating an essential part of a digital audio coder applicable in a digital audio transmission system according to an embodiment of the present invention;
4 is a schematic diagram illustrating a configuration of a transmission frame according to an embodiment of the present invention;
5 is a schematic diagram illustrating a code generator used for transmission error coding in a digital audio transmission system according to an embodiment of the present invention;
FIG. 6 is a chart illustrating output data of a code generator used for transmission error coding in FIG. 5; FIG.
7 is a schematic diagram illustrating the structure of signaling data in a digital audio transmission system according to an embodiment of the present invention;
8 is a chart comparing the audio service quality by the digital audio transmission system of the embodiment of the present invention with that of the prior art.
9 is a schematic diagram illustrating a configuration of a multiplexer of a digital audio transmission system according to an embodiment of the present invention;
10 is an outline view of a DAB transmission frame for transmitting a transmission frame in a digital audio transmission system according to an embodiment of the present invention;

Hereinafter, the configuration of a preferred embodiment of the digital audio transmission system according to the present invention will be described in detail with reference to the accompanying drawings.

In FIG. 2, the digital audio transmission system 100 of the embodiment of the present invention changes the coding method between the core codecs according to the characteristics of the sound source, A framing unit 120 for receiving output data (e.g., sound source frame or AU: ACCESS UNIT) from the sound source coder 110 and converting the received data into a super frame of a predetermined structure; , Transmission error coding means (130) for performing a procedure including transmission error coding for a transmission frame formed by the framing means (120), and one or more transmission frames for one or more logical DAB frames And outputs the signaling data and the service corresponding to the output of the transmission data generating means 150. [ Multiplexing means (200) for multiplexing and outputting the data together with the data including the information data, and a modulator (300) for modulating the multiplexed signal.

The sound source coder 110 of the embodiment of the present invention may include a USAC (United States Speech and Audio Coding) -based encoder proposed by the latest audio technology.

For example, the USAC audio codec shown in FIG. 3 is a codec that appropriately combines the advantages of HE-AAC V2 and AMR-WB +, and selects and operates an appropriate core codec according to characteristics of an input signal. And performs encoding.

 In other words, the USAC adopts a different coding method for the music characteristic signal and the audio characteristic signal, and even when the coding method is used, the subordinate coding method is changed according to the characteristic of the sound source itself and coding can be performed

For example, USAC uses AAC (Advanced Audio Coding), which is a technique for encoding an audio characteristic signal, and AAC technology used in USAC improves performance by changing the existing AAC Huffman lossless coding tool into an arithmetic coding method. In addition, the high frequency band can be encoded using SBR, and in the case of stereo signals, MPEG-Surround technology can be adopted for encoding. Meanwhile, USAC uses ACELP and TCX of AMR-WB +, which is a speech encoding technology of 3GPP, for encoding a voice characteristic signal.

The sound source coder of this embodiment has a signal classifier for classifying the audio characteristic signal and the audio characteristic signal and has a window transition tool for processing the transition between the encoding tools.

For example, the signal classification means receives the sound source signal and analyzes the sound source signal to generate control information that triggers the selection of different coding modes. The analysis of the sound source signal is dependent on the implemented system. The optimal core coding mode is found. In addition, the output of the signal classification means may be implemented to influence the operation of other tools besides, for example, MPEG Surround, enhanced SBR, and time-warped filterbank.

For example, the signal classifying means determines a coding mode for each sound source frame composed of 1024 input samples. First, a series of parameter characteristic points are extracted from the input signal, and then a coding mode is determined.

 For example, the core codec of USAC is a mode tool for performing coding of audio characteristic signals, and improves existing LPC of AMR-WB + as a mode tool for performing voice characteristic signal coding and FD implemented by improving existing MPEG-4 AAC The LPD is divided into the LPD and the LPF. The signal classification means can be used to determine which of the FD and the LPD is primarily used. The ACELP and the TCX can be determined by extracting the parameters of both the time domain and the frequency domain. .

The sound source coder 110 of this embodiment transitions between a plurality of encoding tools in accordance with the control signal generated by the signal classification means and performs coding in the optimal coding mode so that data including information about the transition is generated by coding And may be added as coding information for each sound source frame.

The framing means 120 of the embodiment of the present invention receives the sound source frame (AU: Access Unit) of the bit stream of 16 Kbps as an example of the bit rate of the output of the sound source coder 110 and adapts it to the DAB transmission system And configures a possible transmission frame. For example, the size of the sound source frame, which is the output of the sound source coder, is set in Table 70 (Table 70. Values of coreCoderFrameLength, sbrRatio outputFrameLength and numSlots depending on coreSbrFrameLengthIndex, Information technology, MPEG audio technologies. If one transmission frame is defined as K, one transmission frame may be configured to include K sound source frames, and in addition, K sound source frames may constitute a plurality of transmission frames according to an embodiment.

4, when one transmission frame is composed of K sound source frames, the transmission data is generated by transmission data generation means 150 in order to transmit the transmission frame through the existing DAB transmission system, It can be divided into logical DAB frames and transmitted.

For example, when the sampling rate of the sound source coder 110 is S KHz and the size of the output frame is X, each sound source frame is (X / S) ms and the DAB frame is 24 ms in the time domain. X / S) * K / 24 divided into logical DAB frames and can be transmitted by the DAB transmission system.

In an embodiment of the present invention, for example, the first frame among the N logical DAB frames for transmitting a transmission frame includes header information of a transmission frame, and error coding for protecting the header information, such as LDPC coding or CRC coding, or both And each logical DAB frame may contain information for matching the sync.

Accordingly, the decoding means of the receiving end reconstructs the transmission frame from the N logical DAB frames, extracts the header information, and performs decoding on the transmission frames. In addition, header information of each transmission frame at the receiving end can be subjected to error detection and error correction by decoding, e.g., an LDPC code and / or a CRC code.

At this time, in the error coding for the transmission frame header, the ratio of the output data to the input data may be an optional item according to the service policy. Depending on the embodiment, the ratio may be changed according to the geographical characteristic . Information about this can be included in the signaling data so that transmission frame header error coding can be transmitted through the FIC channel of the DAB frame (FIG. 10).

The transmission error coding means 130 of the present embodiment performs error coding on the entire BYTE data constituting the transmission frame, and the error coding method of this embodiment is, for example, an error coding method of generating an LDPC code by the code generating means of FIG. 5 And may perform vertical data interleaving before and after transmission error coding.

In the embodiment of the present invention, as shown in FIGS. 5 and 6, turbo code generation means for generating output data coded for input data at a predetermined ratio can be used. That is, the amount of coded data generated according to the ratios of 1/2, 1/4, 3/4, etc. of the output data to the input data of the turbo code generation means may be varied.

For example, the ratio of the coded output data to the input data may be optional depending on the service policy, and may be changed according to the area and geographical characteristic of the broadcasting, and the DAB frame May be included in the signaling data transmitted on the FIC channel.

Digital audio broadcasting has a small amount of data for digital video broadcasting. In particular, USAC's digital audio transmission system transmits highly compressed data while header information is complicated compared to a conventional DAB / DAB + digital audio transmission system. Loss of data, especially loss of header information, can have a significant impact on broadcast quality. Therefore, in the embodiment of the present invention, robust error coding is performed on the transmission frame header, and robust transmission error coding based on the LDPC code can be performed on the payload data.

That is, since the LDPC code has a strong error correction function instead of amplifying the data amount, it is easy to apply to the digital audio broadcasting, which transmits the compressed data with a small amount of data and is highly compressed, Can be prevented.

The transmission data generating means 150 of the embodiment of the present invention divides the transmission frame in which the transmission error coding is completed by the transmission error coding means 130 in units of 24 ms which is the transmission time of the logical DAB frame of the MPEG Layer II, To generate a DAB frame. An error correcting code and an error detecting code may be separately given to the data of the logical DAB frame of the embodiment of the present invention.

The transmission frame of the embodiment of the present invention is divided into N logical DAB frames and transmitted. The data of various other broadcasting services (e.g., one or two or more different USAC broadcasting service data, 1 or 2, (E.g., two or more DAB or DAB + broadcasting service data, data broadcasting service data, and the like) and FIC / SI data for the broadcasting service data are multiplexed by the multiplexer 200 to be formed into a DAB transmission frame ).

In this case, for the broadcast service of the embodiment of the present invention, which is transmitted in a logical DAB frame, the audio component type (ASCTy: Audio Service Component Type) of the signaling data transmitted on the FIC channel of the DAB transmission frame Can be specified. That is, as shown in FIG. 7, the FIC channel of the DAB transmission frame is the DAB standard (ETSI EN 300 401 V1.4.1 (2006-06)) FIG. 24 includes signaling data for an audio service component type (ASCTy) in a structure of the service organization field.

For any service k transmitted in the DAB transmission frame (FIG. 10), for example, the kth service component description may specify an audio service component type of 6 bits of b ₁₃ -b ₈ for TMid = 00 (MSC stream audio) The following items are specified.

000000: foreground sound (MPEG Ⅰ or Ⅱ (Layer Ⅱor reserved) coding)

000001: backgroung sound (MPEG Ⅰ or Ⅱ (Layer Ⅱor reserved) coding)

000010: multi-channel audio extension (MPEG Ⅰ or Ⅱ

        (Layer IIor reserved) coding)

111111: HE AAC v ₂

The signaling data for the logical DAB frame for transmitting the transmission frame of this embodiment may use an unassigned value and illustratively 011111 corresponding to USAC may be used as the audio service component type designation value.

It is obvious that the scope of the present invention is not limited to the above embodiments but is defined by the matters defined in the claims of the present invention and includes various modifications and adaptations made by those skilled in the art to the equivalents of the claims.

100 ...... Digital audio transmission system 110 ...... Sound source coder
120 ... frameing means 130 ...... transmission error coding means
150 transmission data generation means 200 multiplexing means
300 ...... Modulator

Claims (8)

A sound source coder for performing an optimized sound source coding by changing a coding method between the core codecs according to different coding schemes according to whether the input sound sources are audio or audio signals and detailed characteristics of the sound sources;
(K) source frames (ACCESS UNITs) constitute one transmission frame (hereinafter referred to as a super frame), or K pieces of sound sources Frame generation means for generating and outputting a transmission frame such that each frame comprises a plurality of transmission frames, each transmission frame including a header and a protection code of the header;
Transmission error coding means for performing a procedure including transmission error coding for generating an error correction code by a turbo code or an LDPC code for a transmission frame formed by the framing means;
And transmission data generation means for generating and outputting at least one transmission frame in which the transmission error coding is completed by dividing the transmission frame into a predetermined number of logical DAB frames.
A sound source coder for performing an optimized sound source coding by changing a coding method between the core codecs according to different coding schemes according to whether the input sound sources are audio or audio signals and detailed characteristics of the sound sources;
(K) source frames (ACCESS UNITs) constitute one transmission frame (hereinafter referred to as a super frame), or K pieces of sound sources Frame generation means for generating and outputting a transmission frame such that each frame comprises a plurality of transmission frames, each transmission frame including a header and a protection code of the header;
Transmission error coding means for performing a procedure including transmission error coding for generating an error correction code by a turbo code or an LDPC code for a transmission frame formed by the framing means;
Transmission data generating means for generating and outputting at least one transmission frame in which the transmission error coding is completed by dividing the transmission frame into a predetermined number of logical DAB frames;
And multiplexing means for receiving the output of the transmission data generating means and multiplexing the data together with the data including the signaling data and the service information data corresponding to the output of the transmission data generating means.
A sound source coder for performing an optimized sound source coding by changing a coding method between the core codecs according to different coding schemes according to whether the input sound sources are audio or audio signals and detailed characteristics of the sound sources;
(K) source frames (ACCESS UNITs) constitute one transmission frame (hereinafter referred to as a super frame), or K pieces of sound sources Frame generation means for generating and outputting a transmission frame such that each frame comprises a plurality of transmission frames, each transmission frame including a header and a protection code of the header;
Transmission error coding means for performing a procedure including transmission error coding for generating an error correction code for a transmission frame formed by the framing means;
And generating and outputting at least one transmission frame in which the transmission error coding is completed to a predetermined number of logical DAB frames, and outputting the error correction code for each logical DAB frame. system.
The system of any one of claims 1 to 3, wherein the transmission error coding means further performs a vertical data interleaving process before or after the transmission error coding.
The apparatus according to claim 2,
Wherein the multiplexing is performed by further including at least one of the other same service type transmission data, DAB transmission data, DAB + transmission data, and data broadcasting data.
The digital audio transmission system of claim 2, wherein the signaling data has the same configuration as the signaling data of the DAB transmission system, and the values of the audio service component type are differently assigned.
The system of claim 1 or 2, wherein the logical DAB frame further comprises an error correction code for each.
The digital audio transmission system according to any one of claims 1 to 3, wherein the header protection code is an LDPC code.

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