KR101455648B1 - Method and System to Encode/Decode Audio/Speech Signal for Supporting Interoperability - Google Patents

Abstract

The present invention relates to a method of encoding an audio / speech signal supporting interoperability, comprising: determining a domain to encode a signal based on information indicating interoperability between a plurality of codecs, And encodes the signal in the determined domain.

Description

TECHNICAL FIELD [0001] The present invention relates to a method and system for encoding / decoding audio / speech signals supporting interoperability,

The present invention relates to a method and system for encoding / decoding an audio / speech signal, and more particularly to a method and system for encoding / decoding an audio / speech signal supporting interoperability.

A method and system for improving the compression efficiency and sound quality by using a small number of bits in encoding or decoding an input speech signal, an audio signal, and a signal in which speech and audio are mixed is required.

SUMMARY OF THE INVENTION An object of the present invention is to provide an audio / speech signal encoding method and system that efficiently encodes both a speech signal and an audio signal, supports interoperability between a plurality of codecs, and a method of encoding an audio / And a computer readable recording medium storing a program for performing the method.

Another object of the present invention is to provide a method and system for decoding an audio / speech signal that efficiently decodes both a speech signal and an audio signal, supports interoperability between a plurality of codecs, and a decoding method of an audio / There is provided a computer-readable recording medium storing a program for executing the program.

According to an aspect of the present invention, there is provided a signal encoding method comprising: determining a domain to encode a signal based on information indicating interoperability between a plurality of codecs; And encoding the signal in the determined domain based on the information.

According to another aspect of the present invention, there is provided a method for encoding a signal, the method comprising: determining a domain to encode a signal based on information indicating interoperability between a plurality of codecs; And encoding the signal in the determined domain based on the information. The present invention also provides a computer-readable recording medium having recorded thereon a program for executing a method of coding a signal.

According to another aspect of the present invention, there is provided a method of decoding a signal, the method comprising: determining a domain in which a result of encoding the signal is to be decoded based on information indicating interoperability between a plurality of codecs included in a signal encoding result step; And decoding the encoded result of the signal in the determined domain based on the information.

According to another aspect of the present invention, there is provided a method of decoding a signal, comprising: determining a domain in which a result of encoding a signal is to be decoded based on information indicating interoperability between a plurality of codecs included in a signal encoding result; And decoding the encoded result of the signal in the determined domain based on the information. The present invention also provides a computer-readable recording medium having recorded thereon a program for executing a method of decoding a signal.

According to another aspect of the present invention, there is provided a signal encoding system for converting a signal into one of a frequency domain of a time domain and a frequency domain of a time domain based on information indicating interoperability between a plurality of codecs, A conversion unit; A mode determining unit for determining a domain to which a signal of each subband is to be encoded based on the information; A time domain encoding unit for encoding a signal of a subband determined to be encoded in a time domain in a time domain using a codec indicating the information; And a frequency domain encoding unit for encoding a signal of a subband determined to be encoded in the frequency domain in the frequency domain.

According to another aspect of the present invention, there is provided a system for decoding a signal, the system for decoding a signal of a signal includes determining a domain to decode an encoding result of the signal based on information indicating interoperability between a plurality of codecs included in a signal encoding result A mode determination unit; A time domain decoding unit for decoding a time domain signal by decoding the encoded result of the signal in the time domain using a codec indicated by the information when it is determined to decode in the time domain; A frequency domain decoding unit for decoding the frequency domain signal by decoding the encoded signal in the frequency domain if it is determined to decode the signal in the frequency domain; And a domain converter for synthesizing the restored time domain signal and the restored frequency domain signal based on the information and converting the synthesized signal to the time domain.

For the embodiments of the invention disclosed herein, specific structural and functional descriptions are set forth for the purpose of describing an embodiment of the invention only, and it is to be understood that the embodiments of the invention may be practiced in various forms, The present invention should not be construed as limited to the embodiments described in Figs.

The present invention is capable of various modifications and various forms, and specific embodiments are illustrated in the drawings and described in detail in the text. It should be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. Similar reference numerals have been used for the components in describing each drawing.

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 commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Do not.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The same reference numerals are used for the same constituent elements in the drawings and redundant explanations for the same constituent elements are omitted.

1 is a conceptual diagram schematically illustrating a codec supporting interoperability according to an embodiment of the present invention.

Referring to FIG. 1, a codec for supporting interoperability includes an encoding unit 10 and a decoding unit 20.

The encoding unit 10 includes an encoder 11 and a multiplexing unit 12. The encoder 11 receives the audio / speech signal IN and interoperability indicator (II) indicating interoperability between the plurality of codecs and encodes the received audio / speech signal based on the received information. The multiplexing unit 12 multiplexes the results encoded by the encoder 11 and outputs the result as a bit stream. The bit stream output from the multiplexing unit 12 is transmitted via the channel 30 or is stored in the storage unit 40.

The decoding unit 20 includes a demultiplexing unit 21 and a decoder 22. The demultiplexing unit 21 demultiplexes the bitstream transmitted through the channel 30 or output from the storage unit 40 to generate the encoded result of the audio / speech signal and the information II indicating the interoperability between the plurality of codecs. . The decoder 22 receives the demultiplexed encoding result and information II from the demultiplexer 21 and decodes the encoded result based on the received information to reconstruct the audio / speech signal.

As described above, the codec for supporting interoperability according to an embodiment of the present invention may have compatibility between a plurality of codecs by separately receiving information (II) indicating interoperability between the plurality of codecs.

FIG. 2 illustrates an example of an interoperability indicator according to an embodiment of the present invention.

An interoperability indicator is information indicating interoperability between a plurality of codecs. Here, interoperability is the ability for a system or product to work well with other systems or products without any special effort on the part of the customer, so that systems of the same or different types can communicate with each other, It is precisely what can be done.

There are various types of codecs for encoding / decoding audio / speech signals in the time domain, and each codec may have different bandwidths or bit rates for performing encoding. As a result, the overall operation of the audio / speech signal encoding / decoding system may vary depending on the kind of the codec for encoding / decoding the audio / speech signal in the time domain. Therefore, in order to support interoperability between a plurality of codecs to be encoded / decoded in the time domain, it is necessary to use an interoperability indicator which is information indicating interoperability in an audio / speech signal encoding / decoding system.

Referring to FIG. 2, the interoperability indicator indicates whether interoperability between a plurality of codecs to be encoded / decoded in the time domain is supported, a bandwidth of a low frequency band signal, which is a key component to be encoded in the audio / And a type of codec to be used in the encoding system of the audio / speech signal.

For example, the interoperability indicator may comprise 5 bits. The most significant bit among the five bits indicates whether or not interoperability between a plurality of codecs to be encoded in the time domain is supported. The second bit indicates whether the bandwidth of the low frequency band signal is narrowband or wideband And the lower bits may indicate information on the type of the codec. Here, the interoperability indicator shown in FIG. 2 is merely an example, and a person skilled in the art will understand that the present invention can have various configurations.

First, if the most significant bit of the interoperability indicator is '0', it indicates that interoperability between a plurality of codecs is not supported. If the most significant bit of the interoperability indicator is '1', interoperability between a plurality of codecs Support.

Next, when the second bit of the interoperability indicator is '1', it indicates that the low frequency band signal can be encoded using the wideband codec. On the other hand, when the second bit of the interoperability indicator is '0', it indicates that the low frequency band signal can be encoded using the narrowband codec.

Finally, if the lower bits of the interoperability indicator are '000', it indicates that a multi-rate codec can be used. Also, when the lower bits of the interoperability indicator are '001', it indicates that a variable rate codec can be used. Also, if the lower bits of the interoperability indicator are '010', it indicates that a scalable codec can be used. And, when the lower bits of the interoperability indicator are '011', it indicates that a single rate codec can be used. In this case, the type of the codec may vary according to whether the low-frequency band signal is encoded using the wideband or narrowband codec.

3 is a block diagram illustrating an audio / speech signal encoding system according to an embodiment of the present invention.

3, the audio / speech signal encoding system includes a stereo encoding unit 310, a down-mixing unit 320, a high frequency band encoding unit 330, A domain conversion unit 340, a mode deciding unit 350, a time domain encoding unit 360, a frequency domain encoding unit 370, And a multiplexing unit (380).

The stereo encoding unit 310 receives the input signal IN and the interoperability indicator II and extracts and encodes a stereo parameter indicating the characteristic relationship between the channels in the received input signal IN. Here, the input signal IN may be a speech signal, an audio signal, or a mixed signal of speech and audio.

The downmixing unit 320 down-mixes the input signal from which the stereo parameter is extracted by the stereo encoding unit 310 and outputs a mono signal. Here, downmixing generates a mono signal of one channel from two or more stereo signals, and can reduce the amount of bits allocated to coding through downmixing. Here, the mono signal may be a signal representative of a stereo signal. In other words, only the mono signal can be encoded and transmitted without encoding each of the left channel signal and the right channel signal included in the stereo signal at the encoding end.

The high frequency band encoding unit 330 refers to the interoperability indicator II and encodes a parameter for a high frequency band signal corresponding to a predetermined frequency or more of the downmixed mono signals in the downmixing unit 320.

4 is a block diagram showing in detail the high frequency band encoding unit included in FIG.

Hereinafter, the operation of the high-frequency band encoding unit will be described with reference to FIGS. The high frequency band coding unit 330 includes a core bandwidth determining unit 331, a high frequency bandwidth determining unit 332, a high frequency band analyzing unit 333, And a high frequency band encoding unit 334.

The core bandwidth determining unit 331 determines whether the bandwidth of the low frequency band signal, which is a core component to be encoded, of the downmixed mono signal is narrow or broadband with reference to the interoperability indicator II. For example, if the second bit of the interoperability indicator of FIG. 2 is '1', the bandwidth of the low frequency band signal is wide, and if it is '0', the bandwidth of the low frequency band signal may be narrow.

The high frequency bandwidth determining unit 332 determines the high frequency bandwidth according to the low frequency band bandwidth determined by the core bandwidth determining unit 331, that is, whether the codec used for encoding the low frequency band signal is a wideband codec or a narrowband codec . More specifically, when the downmixed mono signal is from 20 Hz to 20 kHz, when the low frequency band signal is encoded using the wideband codec, for example, the bandwidth of the low frequency band signal may be up to 6 kHz The high frequency bandwidth determining unit 332 determines the high frequency bandwidth from 6 kHz to 20 kHz. For example, when the low-frequency band signal is encoded using the narrow-band codec, the bandwidth of the low-frequency band signal may be up to 3.4 kHz. The high-frequency bandwidth determining unit 332 may determine the high-frequency bandwidth from 3.4 kHz to 20 kHz .

The high frequency band analyzer 333 analyzes a high frequency band corresponding to the bandwidth determined by the high frequency bandwidth determiner 332. [

The high frequency band encoding unit 334 encodes the parameters for the high frequency band signal based on the analysis result of the high frequency band analyzing unit 333. [ For example, the high-frequency band encoding unit 334 can encode a parameter indicating a high-frequency band component based on the characteristics of the audio / speech signal in which a high correlation exists between the high-frequency and low-frequency bands. As a result, the component of the high frequency band can be estimated by using the coded parameter and the low frequency band signal at the decoding end.

Referring back to FIG. 3, the domain converting unit 340 converts the downmixed signal in the downmixing unit 320 into either a time domain or a frequency domain for each subband. For example, the domain converting unit 340 performs Frequency-Variable Modulated Lapped Transform (FV-MLT) to convert the downmixed signal into a time domain or a frequency domain for each subband. In other words, the domain converter 340 does not convert the signals of all the frequency bands to the time domain or the frequency domain constantly, but may also convert the frequency domain bands into the time domain or the frequency domain according to the determination result of the mode determination unit 350 Can be converted.

More specifically, the domain converting unit 340 includes a converting unit 341 and an inverse transforming unit 342. The transforming unit 341 transforms the downmixed signal into the frequency domain for each subband. For example, the transforming unit 341 may perform a Modified Discrete Cosine Transform (MDCT) and a Modified Discrete Sine Transform (MDST) to convert a downmixed signal into a frequency domain for each subband. Specifically, the transforming unit 341 transforms the downmixed signal into a frequency domain by MDCT, expresses it as a real part, and converts the downmixed signal into a frequency domain by MDST and expresses it as an imaginary part. The inverse transform unit 342 inversely transforms the signal of the predetermined frequency band among the signals converted into the frequency domain by the transform unit 341 into the time domain. For example, the inverse transform unit 342 performs an inverse MDCT (inverse MDCT) on a signal of a predetermined frequency band, and inversely transforms a signal of a predetermined frequency band into a time domain. The specific operation of the inverse transform unit 342 will be described later with reference to Fig.

The mode determining unit 350 determines whether to downmix the downmixed signal in the time domain or the frequency domain for each subband according to a preset reference. More specifically, the mode deciding section 350 decodes the downmixed signal It is possible to decide whether to perform coding in the time domain or in the frequency domain for each subband by using a zero crossing rate method, an energy measurement method, and a pitch variation measurement method.

5 is a block diagram showing in detail the mode determination unit included in FIG.

Hereinafter, the operation of the mode determination unit will be described in detail with reference to FIGS. 3 and 5. FIG. The mode determination unit 350 includes an interoperability indicator confirmation unit 351, a signal analysis unit 352, a parameter extraction unit 353, Determining Unit, 354).

The interoperability indicator confirmation unit 351 refers to the interoperability indicator II and determines whether to downmix the signal in the time domain. Concretely, when the interoperability indicator confirmation unit 351 supports interoperability between a plurality of speech codecs in the time domain as a result of the check of the interoperability indicator (for example, when the most significant bit of the interoperability indicator is' 1 '), It decides to encode the downmixed signal in the time domain. Accordingly, in this case, the mode determination unit 350 can reduce the complexity because it does not need to perform the additional process of coding the downmixed signal in the time domain or the code domain in the frequency domain.

On the other hand, when the interoperability indicator confirmation unit 351 does not support the interoperability between the plurality of speech codecs in the time domain as a result of checking the interoperability indicator, the mode determination unit 350 determines The demodulator 352, the parameter extractor 353, and the mode determiner 354 to determine whether to downmix the signal in the time domain or the frequency domain.

When the interoperability indicator verification unit 351 confirms that the interoperability between the plurality of speech codecs in the time domain is not supported (for example, the most significant bit of the interoperability indicator is " 0 '), the downmixed signal is analyzed, and the analyzed result is supplied to the parameter extraction unit 353.

The parameter extracting unit 353 extracts a parameter for determining the encoding mode from the result of the analysis by the signal analyzing unit 352. [ For example, the parameter extracting unit 353 may extract a parameter for obtaining a zero crossing rate, which is a rate indicating how far the signal moves up and down with respect to the zero point. As another example, the parameter extracting unit 353 can extract a parameter for obtaining the energy level of the signal. As another example, the parameter extracting unit 353 can extract a parameter for obtaining the pitch variation of the signal.

The mode determination unit 354 determines whether the downmixed signal is to be encoded in the time domain or in the frequency domain based on the parameters extracted by the parameter extraction unit 353.

For example, when the parameter for obtaining the zero crossing rate is extracted by the parameter extracting unit 353, the mode determining unit 354 determines that the zero crossing rate is high and the zero crossing rate is low because the unvoiced sound has a high zero crossing rate If it is high, it is encoded in the frequency domain. If the zero crossing rate is low, it can be determined to be encoded in the time domain.

For example, when the parameter extracting unit 353 extracts a parameter for obtaining the energy level of the signal, the mode determiner 354 determines that the energy level of the signal is lower than the energy level of the signal because the unvoiced sound has low energy and the voiced sound has high energy. It can be determined to encode in the frequency domain if it is low and to encode in the time domain if the energy level of the signal is high.

For example, when the parameter extracting unit 353 extracts a parameter for obtaining the pitch change amount of the signal, the mode determining unit 354 determines that the pitch change amount is equal to or larger than the pitch change amount because the unvoiced sound has a large pitch change amount and the voiced sound has a small pitch change amount In many cases, it can be determined to encode in the frequency domain and to encode in the time domain if the pitch variation is small.

The operation of the mode determination unit 350 according to whether or not interoperability between speech codecs to be encoded in the time domain is supported has been described in the embodiment of the present invention. However, in another embodiment of the present invention, Those skilled in the art will appreciate that the operation of the mode determination unit 350 can be changed depending on whether or not the operation support is supported.

Referring back to FIG. 3, when it is determined that the subband is encoded in the time domain for each subband, the signal of the subband output from the mode determination unit 350 is output to the inverse transform unit 342. In addition, when it is determined to perform encoding in the frequency domain for each subband, the signal of the subband output from the mode determination unit 350 is output to the frequency domain encoding unit 370.

The inverse transform unit 342 inverse transforms a signal of a predetermined subband determined to be encoded in the time domain into a time domain in the mode determination unit 350. [ For example, the inverse transform unit 342 performs IMDCT on a signal of a predetermined subband to inverse transform the signal into a time domain.

6 is a block diagram showing in detail the inverse transform unit included in FIG.

Hereinafter, with reference to FIGS. 3 and 6, the operation of the inverse transform unit will be described in detail. The inverse transform unit 342 includes a bandwidth determining unit 3421 and an IMDCT performing unit 3422.

The bandwidth determining unit 3421 receives the MDCT coefficients that are the result of the MDCT performed by the converting unit 341, the result determined by the mode determining unit 350, and the interoperability indicator II. More specifically, when the mode determining unit 350 receives a result determined to be encoded in the time domain, the bandwidth determining unit 3421 determines whether or not the core layer core layer of the low frequency band signal. For example, the bandwidth determining unit 3421 determines the bandwidth of the low frequency band signal according to whether the codec for encoding the low frequency band signal is a wideband codec or a narrowband codec.

The IMDCT performing unit 3422 performs IMDCT on the MDCT coefficients determined according to the bandwidth determined by the bandwidth determining unit 3421 among the MDCT coefficients obtained as a result of the MDCT performed by the converting unit 341, and performs inverse conversion to the time domain.

Referring back to FIG. 3, the time domain encoding unit 360 encodes a signal that is inversely transformed from the inverse transform unit 342 into a time domain in a time domain in the codec determined by referring to the interoperability indicator II.

FIG. 7 is a block diagram showing the time domain encoding unit included in FIG. 3 in detail.

Hereinafter, with reference to FIGS. 2, 3 and 7, the operation of the time domain encoding unit will be described in detail. The time domain encoding unit 360 includes a basic time domain encoding unit 361, wideband codecs 362, and narrowband codecs 363. Here, the description of the operation of the time domain encoding unit 360, for example, of the interoperability indicator of FIG. 2 is for convenience of explanation only, and the interoperability indicator may have various values. Those skilled in the art will understand.

If the interoperability indicator has a value of '0', it indicates that interoperability between different codecs is not supported. In this case, the time domain encoding unit 360 performs encoding in the basic time domain encoding unit 361.

When the interoperability indicator has a value of '11 ~', interoperability between different codecs is supported, and a low-frequency band signal is encoded in a wideband codec. In this case, the time domain encoding unit 360 can select one of the wideband codecs 362.

More specifically, when the interoperability indicator has a value of '11000', the multi-rate codec 3621 may be selected. For example, the multi-rate codec 3621 may be AMR-WB, and the signal that is inversely transformed by the inverse transform unit 342 may be encoded using AMR (Adaptive Multi Rate) -WB.

When the interoperability indicator has a value of '11001', the variable rate codec 3622 may be selected. For example, the variable rate codec 3622 may be EVRC-WB, and the signal that is inversely transformed by the inverse transform unit 342 may be encoded using EVRC (Enhanced Variable Rate Codec) -WB.

When the interoperability indicator has a value of " 11010 ", the scalable rate codec 3623 may be selected. For example, the scalable rate codec 3623 may be G.729.1, and the signal inverted by the inverse transforming unit 342 may be encoded using G.729.1.

If the interoperability indicator has a value of '11011', a single rate codec 3624 may be selected. For example, the single rate codec 3624 may be G.722, and the inverse transformed signal in the inverse transform unit 342 may be coded using G.722.

When the interoperability indicator has a value of '10 ~', interoperability between different codecs is supported, and a low-frequency band signal is encoded in a narrowband codec. In this case, the time domain encoding unit 360 may select one of the narrowband codecs 363.

More specifically, when the interoperability indicator has a value of '10000', the multi-rate codec 3631 may be selected. For example, the multi-rate codec 3631 may be an AMR-NB, and the signal inversely transformed by the inverse transform unit 342 may be encoded using AMR-NB.

When the interoperability indicator has a value of " 10001 ", the variable rate codec 3632 may be selected. For example, the variable rate codec 3632 may be EVRC, and the signal inversely transformed by the inverse transform unit 342 may be encoded using EVRC.

If the interoperability indicator has a value of " 11010 ", the scalable rate codec 3633 may be selected. For example, the scalable rate codec 3633 may be G.729.1 NB, and the signal inverted by the inverse transforming unit 342 may be encoded using G.729.1 NB.

If the interoperability indicator has a value of '11011', a single rate codec 3634 may be selected. For example, the single rate codec 3634 may be G.729, and the signal inverted by the inverse transform unit 342 may be encoded using G.729.

Referring again to FIG. 3, the frequency domain encoding unit 370 encodes the subband signal determined to be encoded in the frequency domain by the mode determination unit 350 in the frequency domain.

The multiplexing unit 380 multiplexes the stereo parameters encoded by the stereo encoding unit 310, the high frequency band signal encoded by the high frequency band encoding unit 330, the result encoded by the time domain encoding unit 360, 370) and outputs the multiplexed result in the form of a bit stream.

8 is a conceptual diagram showing an example of a bit stream output from the multiplexing unit of FIG.

Referring to FIG. 8, the bitstream includes first header information HEADER_1 transmitted on a block basis, second header information HEADER_2 transmitted on a frame basis, first data DATA_1, and second data DATA_2. . Here, a processing unit of an audio signal of a frame is shown, and a predetermined number of frames constitute a block.

The first header information HEADER_1 is transmitted every block to provide random access of the audio signal. For example, the first header information may include channel information, a sampling frequency, a number of frames included in one block, information on whether the block is a randomly accessible block, copyright information, a constant bit rate (CBR) (Variable Bit Rate), and the like.

The second header information HEADER_2 includes an interoperability indicator indicating whether or not interoperability between different codecs is supported, a bitstream length indicating a bit rate of a current data transmission rate, Mode information indicating information on whether the data has been encoded in the frequency domain, and header data others necessary.

The first data (DATA_1) represents N bits assigned to the encoding of the low frequency band signal. For example, in the encoding system of FIG. 3, the result encoded in the time domain encoding unit 360 and the frequency domain encoding unit 370 may be included in the bitstream as the first data.

The second data DATA_2 indicates M bits allocated to another encoding tool such as a stereo encoding unit or a high-frequency band encoding unit. For example, in the encoding system of FIG. 3, a result encoded by the stereo encoding unit 310 and the high-frequency band encoding unit 320 may be included in the bitstream as the second data.

FIGS. 9A to 9D are diagrams showing examples of a bit stream transmitted on a frame-by-frame basis in the bit stream shown in FIG.

9A shows a bit stream applied in communication between codecs of an existing audio / speech signal. In this case, a bitstream including the second header HEADER_2, the first data DATA_1, and the second data DATA_2 may be transmitted on a frame-by-frame basis.

9B shows a bitstream supporting interoperability applied in communication between codecs of an existing audio / speech signal. In this case, a bitstream including the second header HEADER_2, the first data DATA_1, and the second data DATA_2 may be transmitted on a frame-by-frame basis. At this time, the first data includes information for supporting interoperability between different codecs.

FIG. 9C shows a bitstream supporting interoperability applied in communication between general codecs. In this case, a bitstream including the second header HEADER_2 and the first data DATA_1 may be transmitted on a frame-by-frame basis. At this time, the first data includes information for supporting interoperability between different codecs. In addition, since the general codec does not include a separate tool such as a stereo encoding unit or a high-frequency band encoding unit, it does not include the second data.

FIG. 9D shows a bit stream applied when communicating between general codecs that do not require header information. In this case, a bitstream including only the first data (DATA_1) can be transmitted. For example, if the type of the codec to be communicated is known in advance, it is not necessary to send separate header information. In this case, a bitstream containing only the first data can be transmitted. In addition, since the general codec does not include a separate tool such as a stereo encoding unit or a high-frequency band encoding unit, it does not include the second data.

10 is a block diagram illustrating an audio / speech signal decoding system according to an embodiment of the present invention.

10, a system for decoding an audio / speech signal includes a demultiplexing unit 1010, a mode determining unit 1020, a time domain decoding unit 1030, a frequency domain A decoding unit 1040, a domain conversion unit 1050, a high frequency band reconstructing unit 1060, and a stereo reconstructing unit 1070.

The demultiplexer 1010 demultiplexes the bit stream received from the encoder and outputs a low frequency band encoding result, a parameter encoding result for a high frequency band signal, a stereo parameter encoding result, and an interoperability indicator.

The mode determination unit 1020 refers to the interoperability indicator II and determines whether to decode the low frequency band coding result in the time domain or the frequency domain from the demultiplexed result in the demultiplexing unit 1010. [ More specifically, when the interoperability indicator II indicates that the interoperability indicator II supports interoperability between different codecs, the mode determination unit 1020 determines that the encoding result of the low frequency band is to be decoded in the time domain. On the other hand, when the interoperability indicator II indicates that interoperability between different codecs is not supported, the mode determination unit 1020 determines whether to decode the low frequency band enhancement result in the time domain or the frequency domain We judge it according to the existing method.

The time domain decoding unit 1030 decodes the low frequency band coding result in the time domain by referring to the interoperability indicator II when the mode determination unit 1020 decides to decode in the time domain. More specifically, the time domain decoding unit 1030 decodes the low frequency band coding result in the time domain in the codec determined by referring to the interoperability indicator II.

11 is a block diagram showing in detail the time domain decoding unit included in FIG.

Hereinafter, with reference to FIGS. 2, 10 and 11, the operation of the time domain decoding unit will be described in detail. The time domain decoding unit 1030 includes a basic time domain decoding unit 1031, wideband codecs 1032, and narrowband codecs 1033. Here, it is for convenience of explanation that the operation of the time domain decoding unit 1030 is described as an example of the interoperability indicator of FIG. 2, and the interoperability indicator may have various values. Those skilled in the art will understand.

If the interoperability indicator has a value of '0', it indicates that interoperability between different codecs is not supported. In this case, the time domain decoding unit 1030 performs decoding in the basic time domain decoding unit 1031. [

When the interoperability indicator has a value of '11 ~', it indicates that interoperability between other codecs is supported, and a low-frequency band signal is decoded from a wideband codec. In this case, the time domain decoding unit 1030 can select one of the wideband codecs 1032.

More specifically, when the interoperability indicator has a value of '11000', the multi-rate codec 10321 may be selected. For example, the multi-rate codec 10321 may be AMR-WB, and the signal determined to be decoded in the time domain by the mode determination unit 1020 may be decoded using the AMR-WB.

When the interoperability indicator has a value of '11001', the variable rate codec 10322 may be selected. For example, the variable rate codec 10322 may be EVRC-WB, and the signal determined to be decoded in the time domain by the mode determination unit 1020 may be decoded using the EVRC-WB.

If the interoperability indicator has a value of " 11010 ", the scalable rate codec 10323 may be selected. For example, the scalable rate codec 10323 may be G.729.1, and the signal determined to be decoded in the time domain by the mode determination unit 1020 may be decoded using G.729.1.

If the interoperability indicator has a value of '11011', a single rate codec 10324 may be selected. For example, the single rate codec 10324 may be G.722, and the signal determined to be decoded in the time domain by the mode determination unit 1020 may be decoded using G.722.

When the interoperability indicator has a value of '10 ~', it indicates that interoperability between other codecs is supported, and a low-frequency band signal is decoded from a narrowband codec. In this case, the time domain decoding unit 1030 can select one of the narrowband codecs 1033.

More specifically, when the interoperability indicator has a value of '10000', the multi-rate codec 10331 may be selected. For example, the multi-rate codec 10331 may be an AMR-NB, and the signal determined to be decoded in the time domain by the mode determination unit 1020 may be decoded using the AMR-NB.

When the interoperability indicator has a value of '10001', the variable rate codec 10332 may be selected. For example, the variable rate codec 10332 may be an EVRC, and a signal determined to be decoded in the time domain by the mode determination unit 1020 may be decoded using EVRC.

If the interoperability indicator has a value of " 11010 ", the scalable rate codec 10333 may be selected. For example, the scalable rate codec 10333 may be G.729.1 NB, and the signal determined to be decoded in the time domain by the mode determination unit 1020 may be decoded using G.729.1 NB.

If the interoperability indicator has a value of " 11011 ", a single rate codec 10334 may be selected. For example, the single rate codec 10334 may be G.729, and the signal determined to be decoded in the time domain by the mode determination unit 1020 may be decoded using G.729.

Referring again to FIG. 10, the frequency domain decoding unit 1040 decodes the signal determined to be decoded in the frequency domain by the mode determination unit 1020 in the frequency domain.

The domain converter 1050 transforms the result decoded by the time domain decoder 1030 and the frequency domain decoder 1040 into a time domain or a frequency domain. For example, the domain converting unit 1050 applies FV-MLT to convert the result decoded by the time domain decoding unit 1030 and the frequency domain decoding unit 1040 into a time domain or a frequency domain. Here, the domain converting unit 1050 includes a time converting unit 1051 and an inverse transforming unit 1052.

The conversion unit 1051 refers to the interoperability indicator II and converts the result reconstructed by the time domain decoding unit 1030 into the frequency domain. For example, the transform unit 1051 can perform MDCT on the result reconstructed by the time domain decoding unit 1030 by referring to the interoperability indicator II, and convert the time domain to the frequency domain. More specifically, the transform unit 1051 performs MDCT on a subband corresponding to the bandwidth of the low frequency band signal with reference to the interoperability indicator II.

The inverse transform unit 1052 inversely transforms the signal transformed into the frequency domain by the transform unit 1051 and the result decoded by the frequency domain decoding unit 1040 into the time domain. For example, the inverse transform unit 1052 performs IMDCT on the signal converted into the frequency domain by the transform unit 1051 and the result decoded by the frequency domain decoding unit 1040, and inverse transforms the result into the time domain.

The high frequency band decompression unit 1060 decodes the encoding result of the parameter for the demultiplexed high frequency band signal in the demultiplexing unit 1010 and refers to the interoperability indicator II in the inverse transform unit 1052 to the time domain Estimates a high frequency band component from the inversely transformed signal, and restores the signal of the entire band. More specifically, the high frequency band decompression unit 1060 decomposes the high frequency band component from the signal inversely transformed into the time domain in the inverse transform unit 1052 based on the assumption that there is a high correlation between the low frequency band and the high frequency band of the signal .

The stereo reconstruction unit 1070 decodes the result of decoding the demultiplexed stereo parameter in the demultiplexing unit 1010 and upmixes the reconstructed signal in the high frequency band reconstruction unit 1060 using the decoded stereo parameter to generate a stereo signal .

12 is a flowchart illustrating a method of encoding an audio / speech signal according to an embodiment of the present invention.

Referring to FIG. 12, the method of encoding an audio / speech signal according to the present embodiment is comprised of steps of time-series processing in the audio / speech signal encoding system shown in FIG. Therefore, the contents described above with respect to the audio / speech signal encoding system shown in FIG. 3 are applied to the method of encoding an audio / speech signal in this embodiment, even if omitted below.

In step 1200, the mode determination unit 350 identifies an interoperability indicator indicating an instruction or request for interoperability.

In step 1210, the mode determination unit 350 determines whether the interoperability indicator uses the interoperability mode. In other words, the mode determination unit 350 determines whether the interoperability indicator supports the interoperability mode. As a result of the determination, if the interoperability indicator supports the interoperability mode, step 1220 is performed. Otherwise, step 1270 is performed.

In step 1220, the mode determination unit 350 sets the encoding domain to the time domain when the interoperability indicator supports the interoperability mode.

In step 1230, the interoperability indicator is checked and the type of the codec to be encoded is selected. For example, a wideband codec or a narrowband codec is selected.

In step 1240, the encoding bandwidth of the low frequency band signal, which is the core layer to be encoded, is selected. For example, when the low frequency band signal is encoded by the wideband codec as a result of the interoperability indicator, the encoding bandwidth of the low frequency band signal may be from 20 Hz to 6 kHz, and when the low frequency band signal is encoded by the narrowband codec The coding bandwidth of the low frequency band signal can be from 20 Hz to 3.5 kHz.

In step 1250, a high frequency bandwidth to be encoded is selected based on the coding bandwidth of the low frequency band signal. For example, as a result of checking the interoperability indicator, when a low-frequency band signal is encoded with a wide-band codec, the high-frequency bandwidth may range from 6 kHz to 20 kHz, and when a low- frequency band signal is encoded with a narrow- It can range from 3.5 kHz to 20 kHz.

In step 1260, encoding is performed using the codec selected according to the interoperability indicator. For example, if AMR-WB is selected as the result of the interoperability indicator, the low frequency band signal is encoded using AMR-WB.

In step 1270, if the interoperability indicator does not support the interoperability mode, encoding is performed according to the conventional method. More specifically, when the interoperability indicator does not support the interoperability mode, it is encoded in the time domain or the frequency domain depending on the characteristics of the input signal.

In step 1280, it is checked whether the end of the frame is completed. As a result of checking, if all the frames have been encoded, the process is terminated. If not, the interoperability mode is confirmed for the next frame, and steps 1210 to 1270 are repeated until all the frames are encoded.

13 is a flowchart illustrating a method of decoding an audio / speech signal according to an embodiment of the present invention.

Referring to FIG. 13, the method for decoding an audio / speech signal in this embodiment is comprised of steps that are processed in a time-series manner in the audio / speech signal decoding system shown in FIG. Therefore, even if omitted below, the above description of the audio / speech signal decoding system shown in FIG. 10 also applies to the method of decoding an audio / speech signal in this embodiment.

In step 1300, the mode determination unit 1020 identifies the interoperability indicator.

In step 1310, the mode determination unit 1020 determines whether the interoperability indicator uses the interoperability mode. In other words, the mode determination unit 1020 determines whether the interoperability indicator supports the interoperability mode. As a result of the determination, if the interoperability indicator supports the interoperability mode, operation 1320 is performed. Otherwise, operation 1370 is performed.

In step 1320, the mode determination unit 1020 sets the decoding domain to the time domain when the interoperability indicator supports the interoperability mode.

In step 1330, the interoperability indicator is checked and the type of the codec to be decoded is selected. For example, a wideband codec or a narrowband codec is selected.

In step 1340, a decoding bandwidth of a low-frequency band signal, which is a core layer to be decoded, is selected. For example, when the low frequency band signal is decoded by the wideband codec as a result of the check of the interoperability indicator, the decoding bandwidth of the low frequency band signal may be from 20 Hz to 6 kHz, and when the low frequency band signal is decoded by the narrowband codec The decoding bandwidth of the low frequency band signal can be from 20 Hz to 3.5 kHz.

In step 1350, a high frequency bandwidth to be encoded is selected based on the decoding bandwidth of the low frequency band signal. For example, if the interoperability indicator is verified, the high frequency bandwidth may be from 6 kHz to 20 kHz when decoding the low frequency band signal to the wideband codec, and when the low frequency band signal is decoded by the narrowband codec, It can range from 3.5 kHz to 20 kHz.

In step 1360, decoding is performed using the codec selected according to the interoperability indicator. For example, if AMR-WB is selected as a result of the interoperability indicator, the low frequency band signal is decoded using AMR-WB.

In step 1370, if the interoperability indicator does not support the interoperability mode, decoding is performed according to the conventional method. More specifically, when the interoperability indicator does not support the interoperability mode, the input bitstream is identified and decoded in the time domain or the frequency domain.

In step 1380, it is checked whether the end of the frame is completed. If it is determined that all the frames have been decoded, the process ends. Otherwise, it is checked whether the interoperability mode is supported for the next frame, and steps 1310 to 1370 are repeated until decoding of all frames is completed.

FIG. 14 shows an example of a system including an apparatus for encoding and decoding an interoperable audio / speech signal according to an embodiment of the present invention.

Referring to FIG. 14, the system of FIG. 14 includes a Transcoding Rate and Adaptation Unit (TRAU) 1420, a base transceiver station 1420, and a mobile station 1430 on the network side. for Mobile Communication). GSM is a digital mobile phone system widely used in Europe and elsewhere.

Here, the downlink is indicated by a dashed arrow in Fig. 14 as a transmission path from the base station 1420 to the terminal 1430, and the uplink is indicated by a solid line arrow in Fig. 14 as a transmission path from the terminal 1430 to the base station 1420, Respectively.

An Interoperable Speech Encoding Unit (ISPE) is a speech signal encoding unit that supports interoperability according to an embodiment of the present invention. In addition, an interoperable speech decoding unit (ISPD) is a decoding unit of a speech signal supporting interoperability according to an embodiment of the present invention.

It is needless to say that the present invention is not limited to the above-described embodiments, and can be modified by those skilled in the art within the scope of the present invention.

The present invention can also be embodied as computer-readable codes on a computer-readable recording medium. A computer-readable recording medium includes all kinds of recording apparatuses in which data that can be read by a computer system is stored. Examples of the computer-readable recording medium include ROM, RAM, CD-ROM, magnetic tape, hard disk, floppy disk, flash memory, optical data storage, And the like. The computer readable recording medium may also be distributed over a networked computer system and stored and executed as computer readable code in a distributed manner.

1 is a conceptual diagram schematically showing an interoperable codec according to an embodiment of the present invention.

FIG. 2 illustrates an example of an interoperability indicator according to an embodiment of the present invention.

3 is a block diagram illustrating an audio / speech signal encoding system according to an embodiment of the present invention.

4 is a block diagram showing in detail the high frequency band encoding unit included in FIG.

5 is a block diagram showing in detail the mode determination unit included in FIG.

6 is a block diagram showing in detail the inverse transform unit included in FIG.

FIG. 7 is a block diagram illustrating a time domain encoding unit included in FIG. 3 in detail.

8 is a conceptual diagram showing an example of a bit stream output from the multiplexing unit of FIG.

FIGS. 9A to 9D are diagrams showing examples of a bit stream transmitted on a frame-by-frame basis in the bit stream shown in FIG.

10 is a block diagram illustrating an audio / speech signal decoding system according to an embodiment of the present invention.

11 is a block diagram showing in detail the time domain decoding unit included in FIG.

12 is a flowchart illustrating a method of encoding an audio / speech signal according to an embodiment of the present invention.

13 is a flowchart illustrating a method of decoding an audio / speech signal according to an embodiment of the present invention.

FIG. 14 shows an example of a system including an apparatus for encoding and decoding an interoperable audio / speech signal according to an embodiment of the present invention.

Claims (24)

Determining a domain to encode a signal based on information indicating interoperability between the plurality of codecs; And And encoding the signal in the determined domain based on the information, Wherein the encoding step encodes the signal based on a size of a bandwidth included in the information and a codec type in the determined domain. The method according to claim 1, Further comprising the step of converting the signal into one of a time domain and a frequency domain on a subband basis, based on the information, Wherein the step of determining the domain determines a domain to which a signal of each subband is to be encoded. 3. The method of claim 2, The step of converting the signal into one of a time domain and a frequency domain on a subband basis based on the information Wherein a subband selected in accordance with a size of a bandwidth to be encoded in a time domain included in the information is inversely transformed into a time domain. 3. The method of claim 2, The step of determining the domain Wherein when the information indicates that interoperability between the plurality of codecs is supported, it is determined to encode signals of the respective subbands in the time domain. 3. The method of claim 2, The step of encoding the signal Encoding a signal of a subband determined to be encoded in a time domain in a time domain using a codec indicating the information; And And encoding the signal of the subband determined to be encoded in the frequency domain in the frequency domain. 6. The method of claim 5, Extracting and encoding a stereo parameter indicating a characteristic relationship between channels of the signal; And Further comprising the step of downmixing the extracted signal to output a mono signal, And converting the signal into one of a time domain and a frequency domain on a subband basis based on the information And converting the downmixed mono signal into a time domain or a frequency domain for each subband based on the information. The method according to claim 6, Further comprising the step of encoding a parameter for a high frequency band signal having a bandwidth determined based on the information in the downmixed mono signal. 6. The method of claim 5, Further comprising the step of outputting the information and the result encoded in the time domain or the result encoded in the frequency domain in the form of a bit stream every frame. Determining a domain to encode a signal based on information indicating interoperability between the plurality of codecs; And And encoding the signal in the determined domain based on the information, Wherein the encoding step comprises encoding the signal on the basis of a bandwidth size included in the information and a codec type in the determined domain. media. Determining a domain in which a result of encoding the signal is to be decoded based on information indicating interoperability between a plurality of codecs included in an encoding result of the signal; And And decoding the encoding result of the signal in the determined domain based on the information, Wherein the decoding step decodes the encoded result of the signal based on the size of the bandwidth included in the information and the type of the codec in the determined domain. 11. The method of claim 10, The step of determining the domain And when the information indicates interoperability between the plurality of codecs, decides to decode the encoded result of the signal in the time domain. 11. The method of claim 10, The step of decoding the encoding result of the signal Reconstructing a signal in the time domain by decoding the encoded result of the signal in the time domain using the codec indicated by the information if it is determined to decode in the time domain; And And decoding the frequency domain signal by decoding the encoded signal in the frequency domain if it is determined to decode the signal in the frequency domain. 13. The method of claim 12, And combining the recovered time domain and frequency domain signals into a time domain based on the information. 14. The method of claim 13, The step of synthesizing the reconstructed time domain and frequency domain signals into the time domain based on the information Converting a selected subband into a frequency domain according to a size of a bandwidth to be decoded in a time domain included in the information; And And combining the signal of the time domain and the signal of the frequency domain to inverse transform the signal into a time domain. 14. The method of claim 13, Decoding the high frequency band parameter included in the encoding result of the signal based on the information and restoring the signal of the full band using the decoded parameter and the signal converted into the time domain, / RTI > 16. The method of claim 15, Decoding the stereo parameter included in the encoding result of the signal and reconstructing the stereo signal from the restored full-band signal using the decoded stereo parameter. Determining a domain in which a result of encoding the signal is to be decoded based on information indicating interoperability between a plurality of codecs included in an encoding result of the signal; And And decoding the encoding result of the signal in the determined domain based on the information, Wherein the decoding step decodes the encoded result of the signal based on the size of the bandwidth included in the information and the type of the codec in the determined domain. Readable recording medium. A domain converter for converting a signal into one of frequency domains of a time domain on a per-subband basis based on information indicating interoperability between a plurality of codecs; A mode determining unit for determining a domain to which a signal of each subband is to be encoded based on the information; A time domain encoding unit for encoding a signal of a subband determined to be encoded in a time domain in a time domain using a codec indicating the information; And And a frequency domain encoding unit for encoding the signal of the subband determined to be encoded in the frequency domain in the frequency domain. 19. The method of claim 18, Wherein the information includes at least one of whether to support interoperability between the plurality of codecs, a bandwidth size to be encoded in the time domain, and a type of the codec. 19. The method of claim 18, A stereo encoding unit for extracting and encoding a stereo parameter indicating a characteristic relationship between channels of the signal; And Further comprising a downmixing unit for downmixing the extracted signal to output a mono signal, Wherein the domain converter converts the downmixed mono signal into a time domain or a frequency domain for each subband based on the information. 21. The method of claim 20, Further comprising a high frequency band encoding unit for encoding a parameter for a high frequency band signal having a bandwidth determined based on the information in the downmixed mono signal. A mode determination unit for determining a domain to be decoded based on information indicating interoperability between a plurality of codecs included in a signal encoding result; A time domain decoding unit for decoding a time domain signal by decoding the encoded result of the signal in the time domain using a codec indicated by the information when it is determined to decode in the time domain; A frequency domain decoding unit for decoding the frequency domain signal by decoding the encoded signal in the frequency domain if it is determined to decode the signal in the frequency domain; And And a domain converter for combining the recovered time domain signal and the recovered frequency domain signal into a time domain based on the information. 23. The method of claim 22, And a high frequency band decompression unit decoding the high frequency band parameter contained in the result of encoding the signal and restoring a signal of the full band using the decoded parameter and the signal converted into the time domain. system. 24. The method of claim 23, Further comprising a stereo reconstruction unit for reconstructing a stereo signal included in a result of encoding the signal and reconstructing a stereo signal from the restored full-band signal using the decoded stereo parameter, .

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