KR102457303B1 - Usac audio signal encoding/decoding apparatus and method for digital radio services - Google Patents

Abstract

A USAC audio signal encoding/decoding apparatus and method for digital radio service are disclosed. An audio signal encoding method includes: receiving an audio signal; determining a coding scheme for the received audio signal; encoding the audio signal based on the determined coding scheme; and composing an audio stream generated as a result of encoding the audio signal into an audio super frame of a fixed size, wherein the coding scheme is a first coding scheme of Extended High Efficient Advanced Audio Codec (HE-AAC) and an existing one. may include a second coding scheme of the AAC series of .

Description

USAC audio signal encoding/decoding apparatus and method for digital radio service

The present invention relates to a USAC (Unified Speech and Audio Coding) audio signal encoding/decoding apparatus and method for a digital radio service, and more particularly, to determine a coding method for an audio signal, and to determine an audio signal based on the determined coding method It relates to an apparatus and method for encoding/decoding.

USAC is an audio codec technology standardized in MPEG in 2012. Even if the performance of USAC is compared with the previous best technologies (HE-AACv2, AMR-WB+), it showed improved performance results for voice/audio signals, and has high utilization value as a next-generation audio codec technology.

In the past, there was a DAB (Digital Audio Broadcasting) transmission method for a digital radio service. And the DAB+ transmission method that appeared later is a method that can provide better quality digital radio service by improving the audio codec technology used in DAB. The present invention deals with the bitstream structure and framing method required to utilize the USAC audio codec technology, which is the latest codec, in DAB+, and aims to achieve improvement of digital radio services in the future.

The present invention relates to an apparatus and method for encoding/decoding a USAC audio signal for a digital radio service. An apparatus and a method for enabling a USAC-based DAB+ service by providing syntax information and a frame structure for additionally applying USAC to the existing DAB+; provide a way

An audio signal encoding method according to an embodiment of the present invention includes: receiving an audio signal; determining a coding scheme for the received audio signal; encoding the audio signal based on the determined coding scheme; and composing an audio stream generated as a result of encoding the audio signal into an audio super frame of a fixed size, wherein the coding scheme is a first coding scheme of Extended High Efficient Advanced Audio Codec (HE-AAC) and an existing one. may include a second coding scheme of the AAC series of .

The receiving may include: determining whether the type of the received audio signal is a multi-channel audio signal or a mono/stereo audio signal; and performing MPS encoding when it is determined that the received audio signal is a multi-channel audio signal.

The encoding may include performing MPS212 on the received audio signal when the coding method for the received audio signal is determined as the first coding method; performing eSBR on the audio signal output as a result of performing the MPS212; and performing core encoding on an audio signal output as a result of performing the eSBR.

The encoding may include performing PS/SBR on the received audio signal when a coding scheme for the received audio signal is determined as a second coding scheme; and performing encoding on an audio signal output as a result of performing the PS/SBR by using a second coding scheme.

The audio super frame includes a header section including information on the number of boundaries of audio frames included in the audio super frame and information on a reserve fill level of the first audio frame, and included in the audio super frame. It may be composed of a payload section including bit information of audio frames and a directory section including boundary position information of bit strings for each audio frame included in the audio super frame.

The method may further include applying a forward error correction technique to the audio super frame, wherein the applying may correct a bit error generated while the configured audio super frame is transmitted over a communication line.

An audio signal encoding apparatus according to an embodiment of the present invention includes: a receiver for receiving an audio signal; a determining unit that determines a coding scheme for the received audio signal; an encoding unit for encoding the audio signal based on the determined coding method; and a component configured to form an audio stream generated as a result of encoding the audio signal into an audio super frame having a fixed size, wherein the coding scheme is a first coding scheme of Extended High Efficient Advanced Audio Codec (HE-AAC) and a conventional one. may include a second coding scheme of the AAC series of .

When the encoding method for the received audio signal is determined as the first coding method, the encoding unit performs MPS212 on the received audio signal, and performs eSBR on the audio signal output as a result of performing MPS212, As a result of performing eSBR on the output audio signal, core encoding may be performed on the output audio signal.

When the encoding method for the received audio signal is determined as the second coding method, the encoding unit performs PS/SBR on the received audio signal, and performs PS/SBR on the output audio signal as a result of performing the PS/SBR. Encoding may be performed using two coding schemes.

The audio super frame includes a header section including information on the number of boundaries of audio frames included in the audio super frame and information on a reserve fill level of the first audio frame, and included in the audio super frame. It may be composed of a payload section including bit information of audio frames and a directory section including boundary position information of bit strings for each audio frame included in the audio super frame.

An audio signal decoding method according to an embodiment of the present invention comprises the steps of: receiving an audio super frame; determining a decoding method for an audio signal from the received audio super frame; and decoding the audio super frame based on the determined decoding scheme, wherein the decoding scheme includes a first decoding scheme of the Extended High Efficient Advanced Audio Codec (HE-AAC) and a second decoding of an existing AAC sequence. method may be included.

The determining may include: extracting a decoding parameter from the received audio super frame; and determining at least one of the first decoding method and the second decoding method based on the extracted decoding parameter.

The decoding parameter is automatically determined according to a user parameter required for encoding an audio signal, and the user parameter includes bit rate information of a codec for the audio signal, layout type information of the audio signal, and MPEG Surround use for the audio signal. It may include at least one piece of information among whether or not information.

The decoding may include performing core decoding on the received audio super frame when the decoding method for the received audio super frame is determined as the first decoding method; performing eSBR on the audio signal output as a result of the core decoding; and performing MPS212 on the audio signal output as a result of performing the eSBR.

The decoding may include: when the decoding method for the received audio super frame is determined as the second decoding method, performing decoding on the received audio super frame using a second decoding method; and performing PS/SBR on the audio signal output as a result of performing the second decoding method.

The audio super frame includes a header section including information on the number of boundaries of audio frames included in the audio super frame and information on a reserve fill level of the first audio frame, and included in the audio super frame. It may be composed of a payload section including bit information of audio frames and a directory section including boundary position information of bit strings for each audio frame included in the audio super frame.

An audio signal decoding apparatus according to an embodiment of the present invention includes: a receiver for receiving an audio super frame; a determining unit for determining a decoding method for an audio signal from the received audio super frame; and a decoding unit for decoding the audio super frame based on the determined decoding method, wherein the decoding method includes a first decoding method of the Extended High Efficient Advanced Audio Codec (HE-AAC) and a second decoding of an existing AAC series. method may be included.

The determiner may extract a decoding parameter from the received audio super frame, and determine at least one of a first decoding method and a second decoding method based on the extracted decoding parameter.

The decoding parameter is automatically determined according to a user parameter required for encoding an audio signal, and the user parameter includes bit rate information of a codec for the audio signal, layout type information of the audio signal, and MPEG Surround use for the audio signal. It may include at least one piece of information among whether or not information.

According to an embodiment of the present invention, it is possible to enable USAC-based DAB+ service by providing syntax information and a frame structure for additionally applying USAC to the existing DAB+.

1 is a diagram illustrating an encoding system structure of Extended HE-AAC (xHE-AAC) according to an embodiment of the present invention.
2 is a diagram illustrating an encoding apparatus according to an embodiment of the present invention.
3 is a diagram illustrating a structure of a decoding system of Extended HE-AAC (xHE-AAC) according to an embodiment of the present invention.
4 is a diagram illustrating a decoding apparatus according to an embodiment of the present invention.
5 is a diagram illustrating an example of the structure of an xHE-AAC super frame according to an embodiment of the present invention.
6 is a diagram illustrating an example of a super frame payload configuration of a plurality of xHE-AAC audio frames according to an embodiment of the present invention.

Specific structural or functional descriptions of the embodiments according to the concept of the present invention disclosed herein are only exemplified for the purpose of explaining the embodiments according to the concept of the present invention, and the embodiment according to the concept of the present invention These may be embodied in various forms and are not limited to the embodiments described herein.

Since the embodiments according to the concept of the present invention may have various changes and may have various forms, the embodiments will be illustrated in the drawings and described in detail herein. However, this is not intended to limit the embodiments according to the concept of the present invention to specific disclosed forms, and includes changes, equivalents, or substitutes included in the spirit and scope of the present invention.

Terms such as first or second may be used to describe various elements, but the elements should not be limited by the terms. The above terms are used only for the purpose of distinguishing one component from other components, for example, without departing from the scope of rights according to the concept of the present invention, a first component may be named as a second component, Similarly, the second component may also be referred to as the first component.

When a component is referred to as being “connected” or “connected” to another component, it may be directly connected or connected to the other component, but it is understood that other components may exist in between. it should be On the other hand, when it is said that a certain element is "directly connected" or "directly connected" to another element, it should be understood that the other element does not exist in the middle. Expressions describing the relationship between elements, for example, “between” and “between” or “directly adjacent to”, etc. should be interpreted similarly.

The terminology used herein is used only to describe specific embodiments, and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present specification, terms such as "comprise" or "have" are intended to designate that the described feature, number, step, operation, component, part, or combination thereof exists, and includes one or more other features or numbers, It should be understood that the possibility of the presence or addition of steps, operations, components, parts or combinations thereof is not precluded in advance.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in a commonly used dictionary should be interpreted as having a meaning consistent with the meaning in the context of the related art, and should not be interpreted in an ideal or excessively formal meaning unless explicitly defined in the present specification. does not

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. However, the scope of the patent application is not limited or limited by these embodiments. Like reference numerals in each figure indicate like elements.

Hereinafter, in the configuration description of the present invention, the name of Extended HE-AAC (xHE-AAC) will be used instead of the name of USAC. This is because USAC is actually defined in the xHE-AAC profile, and by using the xHE-AAC profile, both USAC and HE-AACv2 can be supported at the same time. Therefore, in the present specification, xHE-AAC may be regarded as USAC.

1 is a diagram illustrating an encoding system structure of Extended HE-AAC (xHE-AAC) according to an embodiment of the present invention.

In order to transmit the xHE-AAC audio stream through the DAB network, a profile suitable for the range and characteristics of parameters for the xHE-AAC audio codec must be defined. In addition, if the compressed xHE-AAC audio stream is to be multiplexed through the DAB main service channel and transmitted, the xHE-AAC encoding device composes the compressed xHE-AAC audio stream into an audio super frame and transmits it according to the actual transmission conditions. .

In addition, the encoding apparatus of the present invention must apply a separate Forward Error Correction (FEC) to ensure robust transmission of the xHE-AAC audio stream, and the xHE-AAC decoding apparatus is DAB+ that applies HE-AAC v2 It should support the decoding function of the audio stream.

The structure of the encoding system of xHE-AAC may be illustrated as shown in FIG. 1 . The audio signal may undergo an encoding process through a selective structure of the xHE-AAC coding scheme (the first coding scheme) and the existing AAC-based coding scheme (the second coding scheme). First, the encoding system structure may determine a coding scheme for an audio signal according to a preset condition, and encode the audio signal based on the determined coding scheme.

In this case, the encoding system structure determines whether the type of the audio signal is a multi-channel audio signal or a mono/stereo signal, and if the audio signal is determined to be a multi-channel audio signal, MPEG Surround (MSP) encoding may be performed first. Thereafter, the encoding system structure may perform an encoding process on a mono or stereo audio signal output by performing MPS encoding.

In the encoding system structure, if the coding scheme for the audio signal is determined as the first coding scheme, MPS212 is performed on the received audio signal, and enhanced spectral band replication (eSBR) is performed on the audio signal output as a result of performing MPS212. and core encoding may be performed on an audio signal output as a result of performing eSBR.

In addition, the encoding system structure performs PS (Parametric Stereo)/SBR (Spectral Band Replication) on the received audio signal when the coding method for the audio signal is determined as the second coding method, and performs PS/SBR. Encoding may be performed on the resultant output audio signal by using the second coding method.

The components of the xHE-AAC coding method include SBR and stereo coding tools like the AAC-series coding tools, but as an independent revision, the standard is not progressed and is included in the xHE-AAC standard technology, so one xHE-AAC Representation by encoding block 110 is appropriate. If there is a difference between the stereo coding tools, the existing AAC-type coding tools use the PS coding method, but xHE-AAC can provide improved stereo sound quality by using the stereo version of MPS212. The SBR module of the xHE-AAC coding method has also been defined and utilized as eSBR (enhanced SBR) by adding some functions.

2 is a diagram illustrating an encoding apparatus according to an embodiment of the present invention.

The encoding apparatus 200 according to an embodiment of the present invention may include a receiving unit 210 , a determining unit 220 , an encoding unit 230 , and a configuration unit 240 . The receiver 210 may receive an audio signal to be encoded. In this case, the audio signal received by the receiver 210 may be a multi-channel audio signal or a mono/stereo audio signal.

The receiver 210 may determine whether the received audio signal is a multi-channel audio signal or a mono/stereo audio signal. In this case, when determining that the received audio signal is a multi-channel audio signal, the receiver 210 may perform MPS encoding to convert the multi-channel audio signal into a mono or stereo audio signal.

The determiner 220 may determine a coding scheme for the audio signal received through the receiver 210 . In this case, the coding scheme may include a first coding scheme of Extended HE-AAC (xHE-AAC) and a second coding scheme of an existing AAC series.

The encoding unit 230 may encode the received audio signal based on the coding method determined by the determiner 220 . For example, when the coding scheme for the received audio signal is determined as the first coding scheme, the encoding unit 230 performs MPS212 on the received audio signal, and eSBR on the audio signal output as a result of performing MPS212 (enhanced spectral band replication) is performed, and core encoding may be performed on an audio signal output as a result of performing eSBR.

In another case, if the coding scheme for the received audio signal is determined as the second coding scheme, the encoding unit 230 performs Parametric Stereo (PS)/Spectral Band Replication (SBR) on the received audio signal, and PS An audio signal output as a result of performing /SBR may be encoded using the second coding method.

The configuration unit 240 may configure an audio stream generated as a result of encoding the received audio signal into an audio super frame having a fixed size. In this case, the audio stream encoded by the first coding method may be transmitted by configuring a plurality of frames as one audio super frame without dividing a boundary.

The application unit (not shown) may apply a forward error correction technique to the audio super frame. In this case, the application unit may correct a bit error occurring while the configured audio super frame is transmitted over the communication line.

3 is a diagram illustrating a structure of a decoding system of Extended HE-AAC (xHE-AAC) according to an embodiment of the present invention.

The xHE-AAC standard is defined by a total of four profile levels (Level), and all profile levels include USAC profile level 2. USAC Profile Level 2 is a profile that supports decoding for mono and stereo signals. Therefore, the xHE-AAC standard must be able to decode into USAC for mono and stereo audio signals. It is assumed that only xHE-AAC profile level 2 is supported in this transmission standard.

That is, the decoding system structure according to the present invention must be able to decode bitstreams for mono and stereo audio signals of USAC, and simultaneously decode bitstreams for mono and stereo audio signals of HE-AAC v2. there should be Support for multi-channel signals can maintain backward compatibility for mono and stereo audio signals by utilizing MPEG Surround technology.

The structure of the decoding system of xHE-AAC may be illustrated as shown in FIG. 3 . The audio super frame received with the decoding system structure may undergo a decoding process through a selective structure of the xHE-AAC coding scheme (first coding scheme) and the existing AAC-series coding scheme (second coding scheme). First, the decoding system may extract a decoding parameter from the received audio super frame, and determine a decoding method based on the extracted decoding parameter. A coding scheme for the audio signal may be determined according to a preset condition, and the audio signal may be encoded based on the determined coding scheme.

In this case, the extracted decoding parameters may be automatically determined according to user parameters required for encoding the audio signal. The user parameter may include at least one information of bit rate information of a codec for an audio signal, layout type information of an audio signal, and information on whether MPEG Surround is used for an audio signal.

In the decoding system structure, if the coding scheme for the audio super frame is determined as the first decoding scheme, core decoding is performed on the received audio super frame, and eSBR is performed on the audio signal output as a result of core decoding, , MPS212 may be performed on an audio signal output as a result of performing eSBR.

In addition, the decoding system structure performs decoding on the received audio super frame by using the second decoding method if the decoding method for the received audio super frame is determined as the second decoding method, and the second decoding method is performed PS/SBR may be performed on the outputted audio signal.

At this time, the decoding system structure determines whether the audio signal output as a result of decoding the received audio super frame is a multi-channel audio signal or a binaural stereo signal for multi-channel, if the audio signal is a multi-channel audio signal If it is determined to be a binaural stereo signal for multi-channel, MPS decoding may be performed.

4 is a diagram illustrating a decoding apparatus according to an embodiment of the present invention.

The decoding apparatus 400 according to an embodiment of the present invention may include a receiving unit 410 , an extracting unit 420 , and a decoding unit 430 . The receiver 410 may receive an audio super frame to be decoded. In this case, the audio super frame received by the receiver 410 includes a header section including information on the number of boundaries of audio frames included in the audio super frame and information on a reserve fill level of the first audio frame; It may be composed of a payload section including bit information of audio frames included in the audio super frame and a directory section including boundary position information of bit strings for each audio frame included in the audio super frame.

The extractor 420 may extract a decoding parameter for decoding the corresponding audio super frame from the audio super frame received through the receiver 410 . At this time, the decoding parameters extracted through the extractor 420 may be automatically determined according to user parameters required for encoding the audio signal, and the user parameters include bit rate information of the codec for the audio signal, layout type information of the audio signal, and At least one piece of information on whether MPEG Surround is used for an audio signal may be included.

The decoding unit 430 may decode the received audio super frame based on the decoding parameter extracted through the extraction unit 420 . If the coding method for the received audio super frame is determined as the first decoding method, the decoding unit 430 performs core decoding on the received audio super frame, and performs core decoding on the output audio signal. eSBR is performed, and MPS212 may be performed on an audio signal output as a result of performing eSBR.

On the other hand, if the decoding method for the received audio super frame is determined as the second decoding method, the decoding unit 430 performs decoding on the received audio super frame using the second decoding method, and the second decoding method PS/SBR may be performed on the audio signal output as a result of this operation.

The audio stream encoded by the first coding method may be transmitted by configuring a plurality of frames as one audio super frame without dividing boundaries.

[Table 1]

Therefore, before interpreting the transmitted audio super frame, syntax information for the basic transmitted audio frame must be extracted. Table 1 above is a syntax function including syntax information indicating this.

[Table 2]

Table 2 above provides an audio codec method used to generate a transmission audio frame. In this case, the transmission audio frame may express the audio coding method through 2 bits.

For example, as shown in Table 2, when the 2 bits represented is 00, it indicates that it is encoded using the existing AAC coding scheme, and when 11, it indicates that it is encoded using the xHE-AAC coding scheme. can Accordingly, when decoding a corresponding transmission audio frame, a decoding apparatus of an existing AAC-based coding scheme or an xHE-AAC coding scheme may be selected from this syntax information.

[Table 3]

Table 3 above may be syntax information for indicating a profile (audio mode) of xHE-AAC for a corresponding transport audio frame when the transport audio frame is decoded using a decoding apparatus of the xHE-AAC coding scheme. In this case, the transmission audio frame may express the method of the audio mode through 2 bits.

For example, as shown in Table 3, when 2 bits expressed in the transmission audio frame are 00, a coding mode for a mono audio signal may be determined, and if 10, a coding mode for a stereo audio signal may be determined.

[Table 4]

Table 4 above may be syntax information on a sample frequency for decoding the transmission audio frame when the transmission audio frame is decoded using a decoding apparatus of the xHE-AAC coding scheme. In this case, the transmission audio frame may express the sample frequency through 3 bits.

For example, as shown in Table 4, when 3 bits expressed in the transmission audio frame are 000, the decoding apparatus of the xHE-AAC coding method may decode the transmission audio frame based on a sample frequency of 12 Hz. Alternatively, when 3 bits expressed in the transmission audio frame are 010, the decoding apparatus of the xHE-AAC coding method may decode the transmission audio frame based on a sample frequency of 24 Hz.

[Table 5]

Table 5 above may be syntax information on whether or not the transmission audio frame includes header information of xHE-AAC when the transmission audio frame is decoded using a decoding apparatus of the xHE-AAC coding method. In this case, the transmission audio frame may express header information of xHE-AAC through 2 bits.

For example, as shown in Table 5, when the 2 bits expressed in the transmission audio frame are 00, the transmission audio frame does not include the header information of xHE-AAC, and when it is 01, the transmission audio frame includes the header information of xHE-AAC. It may indicate that it contains

As mentioned above, a decoding apparatus and related decoding parameters are determined according to bitstream information of an audio frame to be transmitted, and these decoding parameters may be automatically determined by user parameters required when encoding an audio signal as follows.

Audio codec bit rate: Set the bit rate of the audio signal according to the transmission environment

Audio layout type: mono audio signal or stereo audio signal

MPEG Surround enabled or not: Provides backwards compatibility with multichannel services and stereo signals

When the broadcaster simply inputs the user parameters as described above, the audio encoding apparatus of the xHE-AAC coding method may automatically set the parameters for encoding. Most of the user parameters are set and transmitted as static parameters, and sometimes there are user parameters that are changed on a frame-by-frame basis. Although the Dynamic Config information of SBR is an example, most user parameters can be used as they are without change once they are statically set once. Static Config information of the xHE-AAC coding method may be defined as the following syntax function. The following is a syntax element statically defined to set an optimal encoder parameter value from user parameter information set by a broadcaster. Starting from xHEAACStaticConfig(), a decoder parameter value can be extracted from each syntax element information.

[Table 6]

Table 6 may be a syntax function containing information for determining the shape of the decoding device. Starting with this function, the shape of the decoding device may be set.

[Table 7]

[Table 8]

Table 8 may be a syntax function providing information necessary for setting of a decoding apparatus for decoding a mono audio signal. The following syntax functions and information are the same as those defined in xHE-AAC. The UsacCoreConfig function may call syntax information necessary to drive a decoding device corresponding to core coding in the xHE-AAC coding method. In the xHE-AAC coding method, only noiseFilling syntax information that mainly affects sound quality is defined, and the time-warpping tool (tw_mdct), which requires a high amount of computation, is not used.

[Table 9]

Table 9 may be a syntax function providing information necessary for setting of a decoding apparatus for decoding a stereo audio signal.

[Table 10]

Table 10 may be syntax information defining the shape of the SBR decoding apparatus for the xHE-AAC coding scheme. HarmonicSBR, which has a major performance impact, parses and utilizes syntax information from transmitted bit information, and other tools that do not significantly affect performance and increase complexity may not be used. (bs_interTes, bs_pvc, etc.)

[Table 11]

Table 11 may be syntax information related to settings for decoding SBR parameters. All are identical to the USAC syntax, with no additional changes.

[Table 12]

Table 12 is a syntax function for setting the shape of the decoding device of the MPS212. In the xHE-AAC coding scheme, the shape of the MPS may be variously set in combination with the SBR coding mode according to the bit rate. Each syntax information is the same as that of xHE-AAC, and the special thing is that the syntax information for 'bsDecorrConfig' is not transmitted. This is because the MPS module of the xHE-AAC coding method always has bsDecorrConfig == 0.

5 is a diagram illustrating an example of the structure of an xHE-AAC super frame according to an embodiment of the present invention.

The encoding apparatus 200 according to an embodiment of the present invention may configure an audio stream generated as a result of encoding the received audio signal into an audio super frame having a fixed size. In this case, the audio stream encoded by the xHE-AAC coding scheme may be transmitted in which a plurality of frames are configured as one audio super frame without dividing boundaries.

An audio super frame configured by the xHE-AAC coding scheme has a fixed size and may be composed of a header section, a payload section, and a directory section.

The header section may have information on the number of boundaries of audio frames included in the audio super frame and information on a reserve fill level of the first audio frame.

The payload section is a section that has bit information about an audio frame and can store a bit stream in byte units. The boundary between audio frames may be continuously attached and transmitted for each audio frame regardless of the length of the bit string without any additional padding bytes.

The directory section may have boundary position information of a bit string for each audio frame. In this case, the location information is defined only within the corresponding super frame, the location can be explained by a byte unit count, and location information about the 'b' frame boundaries extracted from the header section can be provided.

[Table 13]

In Table 13, bsFrameBorderCount is This is information indicating the number of boundaries of the audio frame bit string that can be carried and transmitted in any one audio super frame payload part. If the bit stream of the last audio frame included in the audio super frame can be completely included in the audio super frame, the number of boundary counts for the audio frame may be equal to the number of audio frames transmitted in the payload section.

bsBitReservoirLevel may indicate the bit exhaustion level of the first audio frame included in the audio super frame. If there is no boundary of the included audio frame, it may represent the total bit exhaustion level of the audio super frame. FixedHeaderCRC can allocate 8 bits as a CRC (Cyclic redundancy check) code for the header section. bsFrameBorderIndex may provide position information in reverse order from the boundary of the last audio frame included in the audio super frame. In this case, the index information for the location information may be represented using 14 bits. bsFrameBorderCount may provide information on the border count of an audio frame. In this case, the boundary count information may be represented using 4 bits, and even if an error occurs in the header information, there may be a plurality of boundary count information, so that the decoding apparatus may not have a problem in finding the audio frame boundary.

6 is a diagram illustrating an example of a super frame payload configuration of a plurality of xHE-AAC audio frames according to an embodiment of the present invention.

The bit stream of the audio frame transmitted to the flow path load part of the audio super frame receives an audio signal in units of an actual fixed audio frame and expresses the encoded result as a bit string to form an audio frame. In this case, the bit string is configured in units of bytes, and a 16-bit CRC code is included.

The xHE-AAC access unit (AU) is information used to generate an audio signal through a decoding device of an actual xHE-AAC coding scheme. Since encoding is performed according to the variable bit rate of the xHE-AAC coding scheme, the size of the AU may be different even for an audio frame signal having the same size. The first bit of the AU is for usacIndependencyFlag. When usacIndependencyFlag is '1', the audio signal of the current frame can be decoded without information on the previous frame. Therefore, at least one audio frame must exist in one audio super frame, and at least one usacIndependencyFlag must be set to 1.

The xHE-AAC access unit CRC also generates a CRC code for the xHE-AAC access unit, and can generate a CRC code by allocating 16 bits per audio frame.

Each of the continuously input audio frame signals may be converted into AUs through an encoding process using the xHE-AAC coding scheme. The fixed bit rate can be guaranteed over a long period, but the number of bits consumed for each audio frame may not be fixed. Accordingly, the length of the AU of the audio frame may be defined differently within the audio super frame. This is to increase the quality of the encoded audio signal. It is determined by referring to the bit exhaustion level so that many bits can be allocated to an audio frame with high difficulty in a long section and a small number of bits can be allocated to an audio frame that is not perceptually important. can This is because transferring the bit exhaustion level to the decoding apparatus can reduce the input AU buffer size and reduce the delay time of the additional audio decoding apparatus.

The encoding device of the xHE-AAC coding scheme may generate a superframe for transmission. For byte alignment of the bit string for the audio frame, xHE-AAC AU can be aligned in bytes by filling in the Null bit.

The boundary of the audio frame does not need to align with the audio super frame, and the bit string for the AU of the audio frame is sequentially connected as a variable bit string according to the input of the audio signal, and is cut according to the fixed bit rate of the audio super frame and transmitted. can be

Accordingly, one audio super frame may include AUs of a variable number of audio frames. However, it is possible to extract and decode the AU of the audio frame based on the header information of the audio super frame and the AU boundary information extracted from the directory information.

If the bit string for the AU of any audio frame does not span 1 byte or more in one audio super frame, the directory section may not include syntax information for 'frame boundary information'. Exactly, boundary information of audio frame data AU less than 3 bytes including 2 bytes related to 'frame boundary information' cannot extract boundary information from the current audio super frame.

In this case, it is expressed in the next audio super frame, and the last 'frame boundary information' of the directory section may indicate information about this. For example, if the last 'frame boundary information' is specified as 0xFFF, the last byte information of the AU for the last audio frame spans the previous frame, and the decoding device uses the previous audio super frame for decoding the last AU frame. 2 bytes of data should always be buffered in the payload part.

Bit exhaustion control is a mechanism commonly utilized in MPEG codes. This shows a variable bit rate in a short section, but can output a fixed bit rate in a long section, so that the best sound quality can be provided within a given section. Accordingly, in the xHE-AAC coding scheme, if the bit exhaustion level is sufficiently high, additional bits may be allocated for coding current frames if necessary, and the bit exhaustion level may be lowered. Conversely, if it is no longer necessary to exhaust the bits, the bit exhaustion level may be increased to allow the bits to be used in a later required section.

The device described above may be implemented as a hardware component, a software component, and/or a combination of the hardware component and the software component. For example, devices and components described in the embodiments may include, for example, a processor, a controller, an arithmetic logic unit (ALU), a digital signal processor, a microcomputer, a field programmable gate array (FPGA). , a programmable logic unit (PLU), microprocessor, or any other device capable of executing and responding to instructions, may be implemented using one or more general purpose or special purpose computers. The processing device may execute an operating system (OS) and one or more software applications running on the operating system. The processing device may also access, store, manipulate, process, and generate data in response to execution of the software. For convenience of understanding, although one processing device is sometimes described as being used, one of ordinary skill in the art will recognize that the processing device includes a plurality of processing elements and/or a plurality of types of processing elements. It can be seen that may include For example, the processing device may include a plurality of processors or one processor and one controller. Other processing configurations are also possible, such as parallel processors.

The software may comprise a computer program, code, instructions, or a combination of one or more thereof, which configures a processing device to operate as desired or is independently or collectively processed You can command the device. The software and/or data may be any kind of machine, component, physical device, virtual equipment, computer storage medium or device, to be interpreted by or to provide instructions or data to the processing device. , or may be permanently or temporarily embody in a transmitted signal wave. The software may be distributed over networked computer systems and stored or executed in a distributed manner. Software and data may be stored in one or more computer-readable recording media.

The method according to the embodiment may be implemented in the form of program instructions that can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, etc. alone or in combination. The program instructions recorded on the medium may be specially designed and configured for the embodiment, or may be known and available to those skilled in the art of computer software. Examples of the computer-readable recording medium include magnetic media such as hard disks, floppy disks and magnetic tapes, optical media such as CD-ROMs and DVDs, and magnetic such as floppy disks. - includes magneto-optical media, and hardware devices specially configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include not only machine language codes such as those generated by a compiler, but also high-level language codes that can be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.

As described above, although the embodiments have been described with reference to the limited embodiments and drawings, various modifications and variations are possible by those skilled in the art from the above description. For example, the described techniques are performed in a different order than the described method, and/or the described components of the system, structure, apparatus, circuit, etc. are combined or combined in a different form than the described method, or other components Or substituted or substituted by equivalents may achieve an appropriate result.

Therefore, other implementations, other embodiments, and equivalents to the claims are also within the scope of the following claims.

200: encoding device
210: receiver
220: decision part
230: encoding unit
240: constituent part
400: decoding device
410: receiver
420: extraction unit
430: decoding unit

Claims (19)

An audio signal encoding method performed by at least one processor, the method comprising:
receiving an audio signal;
determining a coding scheme for each audio super frame of the received audio signal; and
encoding the received audio signal based on the determined coding scheme for each audio super frame; and
composing an audio stream generated as a result of encoding the audio signal into an audio super frame of a fixed size;
including,
The coding scheme is
It includes a first coding scheme of Extended High Efficient Advanced Audio Codec (HE-AAC) related to Unified Speech Audio Coding (USAC) and a second coding scheme of an existing AAC series other than the USAC,
(i) When the coding scheme is determined as the first coding scheme, the encoding comprises:
performing MPS212 encoding on the received audio signal;
performing enhanced Spectral Band Replication (eSBR) on the audio signal output by performing the MPS212 encoding; and
performing core encoding on the audio signal output by performing the eSBR;
(ii) When the coding scheme is determined as the second coding scheme, the encoding comprises:
performing Parametric Stereo (PS) and Spectral Band Replication (SBR) on the received audio signal; and
encoding an audio signal output by performing the PS and SBR using the second coding scheme;
The audio super frame comprising:
When the received audio signal is encoded based on a first coding scheme, the audio signal encoding method including syntax information on whether header information of the first coding scheme is included. According to claim 1,
The receiving step is
determining whether the received audio signal is a multi-channel audio signal or a mono/stereo audio signal; and
performing MPS encoding when it is determined that the received audio signal is a multi-channel audio signal
An audio signal encoding method further comprising a. delete delete The method of claim 1,
The audio super frame,
A header section including information on the number of boundaries of audio frames included in the audio super frame and information on a reserve fill level of a first audio frame, and bit information of audio frames included in the audio super frame An audio signal encoding method comprising: a payload section including According to claim 1,
applying a forward error correction technique to the audio super frame;
further comprising,
The applying step is
An audio signal encoding method for correcting a bit error occurring while the audio super frame is transmitted over a communication line. a receiver for receiving an audio signal;
a determining unit for determining a coding scheme for each audio super frame of the received audio signal; and
an encoding unit for encoding the received audio signal based on a coding scheme determined for each audio super frame;
including,
The coding scheme is
It includes a first coding scheme related to USAC (Unified Speech Audio Coding) and a second coding scheme of the AAC series other than the USAC,
(i) When the coding scheme is determined as the first coding scheme, the encoding unit,
MPS212 encoding, which is a tool for MPS encoding, is performed on the received audio signal, enhanced Spectral Band Replication (eSBR) is performed on the audio signal output by performing the MPS212 encoding, and audio output by performing the eSBR perform core encoding on the signal,
(ii) when the coding scheme is determined as the second coding scheme, the encoding unit,
An audio signal for performing Parametric Stereo (PS) and Spectral Band Replication (SBR) on the received audio signal, and encoding an audio signal output by performing PS and SBR using the second coding scheme. encoding device. delete delete 8. The method of claim 7,
The audio super frame,
A header section including information on the number of boundaries of audio frames included in the audio super frame and information on a reserve fill level of a first audio frame, and bit information of audio frames included in the audio super frame An audio signal encoding apparatus comprising a payload section including An audio signal decoding method performed by at least one processor, the method comprising:
receiving an audio signal comprising an audio super frame;
determining a decoding method for an audio super frame of the received audio signal; and
decoding the audio super frame based on a decoding scheme determined for the audio super frame;
including,
The decoding method is
It includes a first decoding method related to USAC (Unified Speech Audio Coding) and a second decoding method of the AAC series other than the USAC,
(i) when the decoding method is determined as the first decoding method, the decoding step,
performing core decoding on the received audio super frame;
performing enhanced Spectral Band Replication (eSBR) on the audio signal output by performing the core decoding; and
performing MPS212 decoding on the audio signal output by performing the eSBR
including,
(ii) when the decoding method is determined as the second decoding method, the decoding step,
performing decoding on the received audio super frame using the second decoding scheme; and
performing Parametric Stereo (PS) and Spectral Band Replication (SBR) on the audio signal output by performing decoding using the second decoding method
An audio signal decoding method comprising a. 12. The method of claim 11,
The determining step is
extracting decoding parameters from the received audio super frame; and
determining at least one decoding method among a first decoding method and a second decoding method based on the extracted decoding parameter
An audio signal decoding method comprising a. 13. The method of claim 12,
The decoding parameters are
is automatically determined according to the user parameters required when encoding the audio signal,
The user parameters are
An audio signal decoding method comprising at least one of bit rate information of a codec for the audio signal, layout type information of the audio signal, and information on whether MPEG Surround is used for the audio signal. delete delete 12. The method of claim 11,
The audio super frame,
A header section including information on the number of boundaries of audio frames included in the audio super frame and information on a reserve fill level of a first audio frame, and bit information of audio frames included in the audio super frame An audio signal decoding method comprising: a payload section including a receiver for receiving an audio signal including an audio super frame;
a determining unit for determining a decoding method for an audio super frame of the received audio signal; and
A decoding unit for decoding the audio super frame based on the decoding method determined for the audio super frame
including,
The decoding method is
It includes a first decoding method related to USAC (Unified Speech Audio Coding) and a second decoding method of the AAC series other than the USAC,
(i) when the decoding method is determined as the first decoding method, the decoding unit,
Core decoding is performed on the received audio super frame, enhanced Spectral Band Replication (eSBR) is performed on an audio signal output by performing core decoding, and MPS212 decoding is performed on an audio signal output by performing eSBR do,
(ii) when the decoding method is determined as the second decoding method, the decoding unit,
Decoding is performed on the received audio super frame using the second decoding method, and Parametric Stereo (PS) and Spectral Band Replication (SBR) are performed on an audio signal output by performing decoding using the second decoding method. ), an audio signal decoding device that performs 18. The method of claim 17,
The determining unit is
An audio signal decoding apparatus for extracting a decoding parameter from the received audio super frame, and determining at least one of a first decoding scheme and a second decoding scheme based on the extracted decoding parameter. 19. The method of claim 18,
The decoding parameters are
is automatically determined according to the user parameters required when encoding the audio signal,
The user parameters are
An audio signal decoding apparatus comprising at least one of bit rate information of a codec for the audio signal, layout type information of the audio signal, and information on whether MPEG Surround is used for the audio signal.

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