HK1224795B - Harmonic bandwidth extension of audio signals - Google Patents

Description

Harmonic bandwidth extension of audio signals

Priority claim

This application claims priority to U.S. Provisional Application No. 61/939,585, filed on February 13, 2014, and U.S. Non-Provisional Application No. 14/617,524, filed on February 9, 2015, both entitled “Harmonic Bandwidth Extension of Audio Signals,” the entire contents of which are incorporated by reference.

Technical Field

The present invention generally relates to harmonic bandwidth extension of audio signals.

Background Art

Advances in technology have resulted in smaller and more powerful computing devices. For example, there are currently a variety of portable personal computing devices, including wireless computing devices, such as portable wireless telephones, personal digital assistants (PDAs), and paging devices, that are small, lightweight, and easily carried by users. More specifically, portable wireless telephones (e.g., cellular telephones and Internet Protocol (IP) telephones) can communicate voice and data packets over wireless networks. In addition, many such wireless telephones include other types of devices incorporated therein. For example, a wireless telephone may also include a digital still camera, a digital video camera, a digital recorder, and an audio file player.

In traditional telephone systems, such as the Public Switched Telephone Network (PSTN), signal bandwidth is limited to a frequency range of 300 Hz to 3.4 kHz. In wideband (WB) applications, such as cellular telephony and Voice over Internet Protocol (VoIP), signal bandwidth can span a frequency range of 50 Hz to 7 kHz. Ultra-wideband (SWB) coding technology supports bandwidth extension to approximately 16 kHz. Extending the signal bandwidth from narrowband telephony at 3.4 kHz to SWB telephony at 16 kHz improves the quality, intelligibility, and fidelity of signal reconstruction.

SWB coding technology generally relates to the lower frequency part (for example, 50Hz to 7kHz, also referred to as " low-frequency band ") of coding and transmission signal. For example, filter parameters and/or low-frequency band excitation signal can be used to represent low-frequency band. In order to improve decoding efficiency, the higher frequency part (for example, 7kHz to 16kHz, also referred to as " high-frequency band ") of coding and transmission signal may not be fully encoded. Receiver can utilize signal modeling to produce synthetic high-frequency band signal. In some implementations, the data associated with high-frequency band can be provided to receiver to assist high-frequency band synthesis. Such data can be referred to as " side information ", and can comprise gain information, line spectrum frequency (LSF, also referred to as line spectrum pair (LSP)) etc. Can produce side information by comparing high-frequency band and the synthetic high-frequency band signal that is derived from low-frequency band. For example, synthetic high-frequency band signal can be based on low-frequency band signal and nonlinear function. Single nonlinear function can be used for producing synthetic high-frequency band signal for a plurality of low-frequency band signals with different characteristics. Applying the same nonlinear function to signals with dissimilar characteristics may result in a low-quality synthesized high-band signal in some cases (eg, speech versus music). As a result, the synthesized high-band signal may be weakly correlated with the high-band signal.

Summary of the Invention

Disclosed are systems and methods for harmonic bandwidth extension of an audio signal. An encoder can use a low-frequency band portion of an audio signal to generate information (e.g., adjustment parameters) for reconstructing a high-frequency band portion of the audio signal at a decoder. For example, the encoder can extend the low-frequency band portion of the audio signal based on characteristics of the low-frequency band portion. The extended low-frequency band portion can have a bandwidth greater than the low-frequency band portion. The encoder can determine the adjustment parameters based on the extended low-frequency band portion and the high-frequency band portion.

The encoder can use a selected nonlinear processing function to produce an extended low-frequency band portion. The nonlinear processing function can be selected from a plurality of nonlinear processing functions based on the characteristics of the low-frequency band portion of the audio signal. The audio signal can correspond to a specific audio frame or data packet. If the low-frequency band portion indicates that the audio signal is strongly periodic (e.g., has a strong harmonic component and/or corresponds to speech), the signal encoder can select a higher-order nonlinear function. If the low-frequency band portion indicates that the audio signal is strongly noisy (e.g., corresponding to music), the signal encoder can select a lower-order nonlinear function. The encoder can determine the adjustment parameter based on the comparison of the high-frequency band and the extended low-frequency band portion.

Decoder can receive low-frequency band data and adjustment parameters from encoder.Decoder can produce synthetic low-frequency band signal based on low-frequency band data.Decoder can produce synthetic extended low-frequency band part based on synthetic low-frequency band signal and selected nonlinear processing function.Decoder can produce synthetic high-frequency band signal based on synthetic extended low-frequency band part and adjustment parameters.Output signal can be produced by combining synthetic low-frequency band signal and synthetic high-frequency band signal at decoder place.

In a specific embodiment, a method comprises dividing an input audio signal into at least a low-band signal and a high-band signal at a device. The low-band signal corresponds to the low-band frequency range and the high-band signal corresponds to the high-band frequency range. The method also comprises selecting a nonlinear processing function among a plurality of nonlinear processing functions. The method further comprises generating a first extended signal based on the low-band signal and the nonlinear processing function. The method also comprises generating at least one adjustment parameter based on the first extended signal, the high-band signal or both.

In another specific embodiment, a method comprises receiving the low-frequency band data of at least the low-frequency band signal corresponding to the input audio signal at the device. Said method also comprises decoding the low-frequency band data to produce a synthetic low-frequency band audio signal. Said method further comprises selecting a non-linear processing function among a plurality of non-linear processing functions. Said method also comprises producing a synthetic high-frequency band audio signal based on the synthetic low-frequency band audio signal and the non-linear processing function.

In another specific embodiment, a kind of device comprises memory and processor.Described processor is configured to divide input audio signal into at least low-frequency band signal and high-frequency band signal.Low-frequency band signal corresponds to low-frequency band frequency range and high-frequency band signal corresponds to high-frequency band frequency range.Described processor is also configured to select the nonlinear processing function in a plurality of nonlinear processing functions.Described processor is further configured to produce first extended signal based on low-frequency band signal and nonlinear processing function.Described processor is also configured to produce at least one adjustment parameter based on first extended signal, high-frequency band signal or both.

In another specific embodiment, a kind of device comprises memory and processor.Described processor is configured to receive the low-frequency band data corresponding to at least the low-frequency band signal of input audio signal.Described processor is also configured to decode the low-frequency band data to produce synthetic low-frequency band audio signal.Described processor is further configured to select the nonlinear processing function in a plurality of nonlinear processing functions.Described processor is also configured to produce synthetic high-frequency band audio signal based on synthetic low-frequency band audio signal and nonlinear processing function.

In another specific embodiment, the computer readable storage device stores an instruction that causes the processor to perform an operation that includes dividing the input audio signal into at least a low-frequency band signal and a high-frequency band signal when the processor performs the operation. The low-frequency band signal corresponds to the low-frequency band frequency range and the high-frequency band signal corresponds to the high-frequency band frequency range. The operation also includes selecting the nonlinear processing function in a plurality of nonlinear processing functions. The operation further includes producing a first extended signal based on the low-frequency band signal and the nonlinear processing function. The operation also includes producing at least one adjustment parameter based on the first extended signal, the high-frequency band signal or both.

In another specific embodiment, the computer readable storage device stores an instruction that causes the processor to perform an operation that comprises receiving the low-frequency band data of at least the low-frequency band signal corresponding to the input audio signal when the processor is executed. The operation also comprises decoding the low-frequency band data to produce a synthetic low-frequency band audio signal. The operation further comprises the nonlinear processing function that selects a plurality of nonlinear processing functions. The operation also comprises producing a synthetic high-frequency band audio signal based on the synthetic low-frequency band audio signal and the nonlinear processing function.

The specific advantage provided by at least one of the disclosed embodiments can comprise the quality of the synthetic high-frequency band portion of improved output signal.Can produce the synthetic high-frequency band portion and improve the quality of output signal from the nonlinear function of a plurality of available nonlinear processing functions selection by using the audio characteristic based on low-frequency band portion.Selected nonlinear function can improve the dependency between the synthetic high-frequency band portion of the input signal at encoder place and the output signal at decoder place under voice situation and non-voice situation (for example, music).Other aspects of the present invention, advantage and feature will become apparent after reviewing the application case that comprises following chapters and sections: [simple description of figures], [embodiment] and [claim].

BRIEF DESCRIPTION OF THE DRAWINGS

1 is a diagram illustrating a particular embodiment of an encoder system operable to perform harmonic bandwidth extension of an audio signal;

2 is a diagram of another particular embodiment of a decoder system operable to perform harmonic bandwidth extension of an audio signal;

3 is a diagram of another particular embodiment of a system operable to perform harmonic bandwidth extension of an audio signal;

4 is a flow chart illustrating a particular embodiment of a method of performing harmonic bandwidth extension of an audio signal;

FIG5 is a flow chart illustrating another particular embodiment of a method of performing harmonic bandwidth extension of an audio signal; and

6 is a block diagram of a wireless device operable to perform signal processing operations according to the systems and methods of FIGs. 1-5.

DETAILED DESCRIPTION

1 , a diagram of a particular embodiment of an encoder system operable to perform harmonic bandwidth extension of an audio signal is shown and generally designated 100. In a particular embodiment, encoder system 100 may be integrated into an encoding (or decoding) system or device, such as a wireless telephone or a codec/decoder (CODEC). In other embodiments, encoder system 100 may be integrated into a set-top box, a music player, a video player, an entertainment unit, a navigation device, a communication device, a personal digital assistant (PDA), a fixed location data unit, or a computer.

It should be noted that in the following description, the various functions performed by the encoder system 100 of FIG. 1 are described as being performed by certain components or modules. This division of components and modules is for illustrative purposes only and is not to be considered limiting. In alternative embodiments, the functions performed by a particular component or module may be divided among multiple components or modules. Furthermore, in alternative embodiments, two or more components or modules of FIG. 1 may be integrated into a single component or module. Each component or module illustrated in FIG. 1 may be implemented using hardware (e.g., a field programmable gate array (FPGA) device, an application-specific integrated circuit (ASIC), a digital signal processor (DSP), a controller, etc.), software (e.g., instructions executable by a processor), or any combination thereof.

The encoder system 100 includes an analysis filter bank 110 coupled to a lowband encoder 108, a harmonicity estimator 106, a signal generator 112, and a parameter estimator 190. The signal generator 112 is coupled to a filter 114 and a mixer 116. The signal generator 112 may include a function selector 180.

During operation, the analysis filter bank 110 may receive an input audio signal 102. For example, the input audio signal 102 may be provided by a microphone or other input device. The input audio signal 102 may include speech, noise, music, or a combination thereof. The input audio signal 102 may be an ultra-wideband (SWB) signal, which includes data within a frequency range of approximately 50 hertz (Hz) to approximately 16 kilohertz (kHz). The analysis filter bank 110 may separate the input audio signal 102 into a plurality of portions based on frequency. For example, the analysis filter bank 110 may separate the input audio signal 102 into at least a low-band signal 122 and a high-band signal 124. In a particular embodiment, the analysis filter bank 110 may include a set of analysis filter banks. The set of analysis filter banks may separate the input audio signal 102 into at least a low-band signal 122 and a high-band signal 124. In a particular embodiment, the analysis filter bank 110 may generate two or more outputs.

In the example of Fig. 1, low-band signal 122 and high-band signal 124 occupy non-overlapping frequency bands. For example, low-band signal 122 and high-band signal 124 can occupy non-overlapping frequency bands of 50Hz to 7kHz and 7kHz to 16kHz respectively. In an alternative embodiment, low-band signal 122 and high-band signal 124 can occupy non-overlapping frequency bands of 50Hz to 8kHz and 8kHz to 16kHz respectively. In another alternative embodiment, low-band signal 122 and high-band signal 124 overlap (for example, 50Hz to 8kHz and 7kHz to 16kHz respectively), and this situation can make the low-pass filter and high-pass filter of analysis filter bank 110 have smooth roll-off, so can simplify design and reduce the cost of low-pass filter and high-pass filter. Making low-band signal 122 and high-band signal 124 overlap can also allow to realize the smooth mixing of low-band and high-band signal at receiver, so can produce less audible artifacts.

It should be noted that although the example of FIG1 illustrates the processing of SWB signals, this is for illustrative purposes only and should not be considered limiting. In an alternative embodiment, the input audio signal 102 may be a wideband (WB) signal having a frequency range of approximately 50 Hz to approximately 8 kHz. In this embodiment, the low-band signal 122 may correspond to a frequency range of approximately 50 Hz to approximately 6.4 kHz and the high-band signal 124 may correspond to a frequency range of approximately 6.4 kHz to approximately 8 kHz.

The analysis filter bank 110 can provide the low-band signal 122 to the low-band encoder 108 and can provide the high-band signal 124 to the parameter estimator 190. As described herein, the parameter estimator 190 can be configured to compare the first extended signal 182 with the high-band signal 124 to produce one or more adjustment parameters 178. As described herein, the encoder system 100 can be based on the low-band signal 122 and through selected nonlinear processing function to produce the first extended signal 182. The mixer 116 can be configured to produce the first extended signal 182 by using the noise signal 176 modulation second extended signal 172. The filter 114 can be configured to produce the second extended signal 172 by filtering the third extended signal 174 from the signal generator 112.

The low-band encoder 108 may receive the low-band signal 122 from the analysis filter bank 110 and may generate low-band parameters 168. The low-band parameters 168 may indicate characteristics of the low-band signal 122. The low-band parameters 168 may include values of the low-band signal 122 associated with spectral tilt, pitch gain, hysteresis, voice mode, or a combination thereof.

Spectral tilt may relate to the shape of the spectral envelope over the passband and may be represented by a quantized first reflection coefficient. For voiced sounds, the spectral energy may decrease with increasing frequency, such that the first reflection coefficient is negative and may be close to -1. Unvoiced sounds may have a spectrum that is flat, such that the first reflection coefficient is close to zero, or have more energy at high frequencies, such that the first reflection coefficient is positive and may be close to +1.

The speech pattern parameter can have the binary value of one or more measurement results (for example, the relation between this type of measurement result and threshold value) of the speech activity based on periodicity (for example, zero crossing, standardization autocorrelation function (NACF), pitch gain etc.) and/or audio frame.In other implementations, the speech pattern parameter can have one or more other states to indicate the pattern of for example silence or background noise, or the transition between silence and the voiced speech.Low-band encoder 108 can provide low-band parameters 168 to signal generator 112.

In a particular embodiment, the signal generator 112 may generate the low-band signal 122 based on the low-band parameters 168. For example, the signal generator 112 may include a local decoder (or decoder emulator). The local decoder may simulate the behavior of a decoder at the receiving device. For example, the local decoder may be configured to decode the low-band parameters 168 to generate the low-band signal 122. In an alternative embodiment, the signal generator 112 may receive the low-band signal 122 from the analysis filter bank 110.

The function selector 180 may select a nonlinear processing function from the plurality of available nonlinear processing functions 118. The plurality of available nonlinear processing functions 118 may include an absolute value function, a full-wave rectification function, a half-wave rectification function, a square function, a cubic function, a power of four function, a clipping function, or a combination thereof.

Function selector 180 can select nonlinear processing function based on the characteristic of low-band signal 122. For illustration, function selector 180 can determine characteristic value based on low-band parameter 168 or low-band signal 122. Noise factor can indicate the periodicity of the audio frame corresponding to low-band signal 122. For example, noise factor can correspond to pitch gain, voice mode, spectrum tilt, NACF, zero crossing or its combination associated with low-band signal 122. If noise factor satisfies the first noise threshold, function selector 180 can select the first nonlinear processing function so. For example, if noise factor indicates that low-band signal 122 is strongly periodic (for example, corresponding to voice), function selector 180 can select high-order power function (for example, four power functions). If noise factor satisfies the second noise threshold, function selector 180 can select the second nonlinear processing function so. For example, if the noise factor indicates that the low-band signal 122 is not very periodic or is noise-like (eg, corresponding to music), the function selector 180 may select a low-order power function (eg, a square function).

In a particular embodiment, the function selector 180 may select a nonlinear processing function from a plurality of available nonlinear processing functions 118 on an audio frame-by-audio frame basis. Furthermore, different nonlinear processing functions may be selected for consecutive frames of the input audio signal 102. Thus, the function selector 180 may select a first nonlinear processing function from a plurality of nonlinear processing functions in response to determining that a parameter associated with a first audio frame satisfies a first condition, and may select a second nonlinear processing function from a plurality of nonlinear processing functions in response to determining that a parameter associated with a second audio frame satisfies a second condition. As an illustrative example, a different nonlinear processing function may be applied when the input audio signal 102 corresponds to speech during a phone call than when the input audio signal 102 corresponds to music on hold during a phone call. In a particular embodiment, the parameter associated with the frame is one of a coding mode selected to encode a low-band signal, the periodicity of the frame, the amount of non-periodic noise in the frame, and a spectral tilt corresponding to the frame.

Signal generator 112 can expand the spectrum of low-band signal 122 in a harmonic manner to include higher frequency range (for example, corresponding to the frequency range of high-band signal 124).For example, signal generator 112 can increase sampling to low-band signal 122. Low-band signal 122 can be through increasing sampling to reduce the frequency overlap after the selected non-linear processing function of application. In a specific embodiment, signal generator 112 can be by specific factor (for example, 8) low-band signal 122 is increased sampling. In a specific embodiment, increasing the sampling operation can comprise that low-band signal 122 is carried out zero padding. Signal generator 112 can be by selected non-linear processing function being applied to produce the 3rd extended signal 174 through increasing the sampled signal.

Filter 114 can receive the 3rd extended signal 174 from signal generator 112.Filter 114 can produce the second extended signal 172 by filtering the 3rd extended signal 174.For example, filter 114 can reduce sampling so that the frequency range of the second extended signal 172 (for example, 7kHz to 16kHz) corresponds to the frequency range associated with high-frequency band signal 124 to the 3rd extended signal 174.For illustration, filter 114 can be applied to the 3rd extended signal 174 to produce the second extended signal 172 with band-pass (for example, high-pass) filtering operation. In a particular embodiment, filter 114 can be applied to the 3rd extended signal 174 with linear conversion (for example, discrete cosine transform (DCT)) and can select the transform coefficient corresponding to high frequency range (for example, 7kHz to 16kHz).Filter 114 can provide the second extended signal 172 to mixer 116.

The mixer 116 can combine the second spread signal 172 and the noise signal 176. The mixer 116 can receive the noise signal 176 from a noise generator (not shown). The noise generator can be configured to generate a unit variance white pseudo-random noise signal. In a specific embodiment, the noise signal 176 may not be white and may have a power density that varies with frequency. In a specific embodiment, the noise generator can be configured to output the noise signal 176 as a deterministic function that can be replicated at a decoder of a receiving device. For example, the noise generator can be configured to generate the noise signal 176 as a deterministic function of the low-band parameters 168.

Frequency mixer 116 can combine the noise signal 176 of the first ratio and the second extended signal 172 of the second ratio.For example, frequency mixer 116 can produce the first extended signal 182 with the harmonic energy of the ratio that is similar to the harmonic energy of high frequency band signal 124 and noise energy and the ratio of noise energy.Frequency mixer 116 can determine the first ratio and the second ratio based on harmonic property factor 170.For example, if harmonic property factor 170 indicates that high frequency band signal 124 is associated with silent sound (for example, music or noise), the first ratio can be higher than the second ratio so.As another example, if harmonic property factor 170 indicates that high frequency band signal 124 is associated with voiced speech, the second ratio can be higher than the first ratio.In a particular embodiment, frequency mixer 116 can determine the first ratio (or the second ratio) from harmonic property factor 170 and can derive the second ratio (or the first ratio) according to the equation such as following formula:

(first ratio) ² +(second ratio) ² =1, (Equation 1).

Alternatively, mixer 116 may select a corresponding ratio pair from a plurality of ratio pairs based on harmonicity factor 170, where the ratio pairs are pre-calculated to satisfy a constant energy ratio, such as equation (1). The value of the first ratio may range from 0.1 to 0.7 and the value of the second ratio may range from 0.7 to 1.0.

The harmonicity estimator 106 may determine the harmonicity factor 170 based on an estimate of a characteristic (e.g., periodicity) of the input audio signal 102. In a particular embodiment, the harmonicity estimator 106 may generate the harmonicity factor 170 based on at least one of the high-band signal 124 and the low-band parameters 168. For example, the harmonicity estimator 106 may determine the harmonicity factor 170 based on a characteristic (e.g., periodicity) of the low-band signal 122 indicated by the low-band parameters 168. For illustration, the harmonicity estimator 106 may assign a value proportional to the pitch gain to the harmonicity factor 170. As another example, the harmonicity estimator 106 may determine the harmonicity factor 170 based on a speech mode. For illustration, the harmonicity factor 170 may have a first value in response to a speech mode indicating voiced audio (e.g., speech) and may have a second value in response to a speech mode indicating unvoiced audio (e.g., music).

In one embodiment, harmonic estimator 106 can be used to determine harmonic factor 170 based on the characteristic (for example, periodicity) of high frequency band signal 124.For illustration, harmonic estimator 106 can be used to determine harmonic factor 170 based on the maximum value of the autocorrelation coefficient of high frequency band signal 124, wherein in the search range that comprises the delay of a tone lag and does not comprise the delay of zero sample, carry out autocorrelation.In a particular embodiment, harmonic estimator 106 can produce the high frequency band filter parameter corresponding to high frequency band signal 124 and can determine the characteristic of high frequency band signal 124 based on the high frequency band filter parameter.

In a particular embodiment, harmonicity estimator 106 can determine harmonicity factor 170 based on another indicator (for example, pitch gain) and threshold value of periodicity.For example, if the pitch gain indicated by low-frequency band parameter 168 satisfies the first threshold value (for example, being greater than or equal to 0.5), harmonicity estimator 106 can be carried out autocorrelation operation to high-frequency band signal 124 so.As another example, if the speech mode indicates a particular state (for example, voiced speech), harmonicity estimator 106 can be carried out autocorrelation operation so.If pitch gain does not satisfy the first threshold value and/or if the speech mode indicates other state, harmonicity factor 170 can have default value so.

Harmonicity estimator 106 can be based on the characteristic determination harmonicity factor 170 that is different from periodicity or except periodicity.For example, harmonicity factor can have different values for the voice signal with large pitch lag and the voice signal with small pitch lag.In a particular embodiment, harmonicity estimator 106 can be based on the measurement of the energy of high frequency band signal 124 with respect to the measurement of the energy of high frequency band signal 124 under other frequency components to determine harmonicity factor 170 under the multiple of fundamental frequency.

The harmonicity estimator 106 may provide the harmonicity factors 170 to the mixer 116. As described herein, the mixer 116 may generate a first spread signal 182 based on the harmonicity factors 170. The mixer 116 may provide the first spread signal 182 to a parameter estimator 190.

Parameter estimator 190 can produce adjustment parameter 178 based on at least one in high frequency band signal 124 or the first extended signal 182.For example, parameter estimator 190 can produce adjustment parameter 178 based on the relationship between high frequency band signal 124 and the first extended signal 182 (for example, the difference between the energy of two signals or the ratio).In a particular embodiment, adjustment parameter 178 can correspond to the difference between the energy of two signals of indication or one or more gain adjustment parameters of the ratio.In an alternate embodiment, adjustment parameter 178 can correspond to the quantized index of the gain adjustment parameter.In a particular embodiment, adjustment parameter 178 can comprise the high frequency band parameter of the characteristic of indication high frequency band signal 124.In a particular embodiment, parameter estimator 190 can be based on high frequency band signal 124 and not based on the first extended signal 182 to produce adjustment parameter 178.

Parameter estimator 190 can provide adjustment parameter 178 and low-band encoder 108 and low-band parameters 168 can be provided to multiplexer (MUX).MUX can multitask adjustment parameter 178 and low-band parameters 168 to produce output bit stream.Output bit stream can represent the encoded audio signal corresponding to input audio signal 102.For example, MUX can be configured to insert adjustment parameter 178 into the encoded version of input audio signal 102 to realize gain adjustment during the reproduction of input audio signal 102.Output bit stream can be transmitted (for example, via wired, wireless or optical channel) and/or through storage by transmitter.At receiving device place, can be performed reverse operation to produce audio signal (for example, be provided to the reconstruction version of input audio signal 102 of loudspeaker or other output device) by demultiplexer (DEMUX), low-band decoder, high-band decoder and filter bank, as described with reference to Fig. 2. In a particular embodiment, the harmonicity estimator 106 may provide the harmonicity factor 170 to the MUX, and the MUX may include the harmonicity factor 170 in the output bitstream.

The encoder system 100 generates a synthetic high-band signal (e.g., a first extended signal 182) at the encoder using a nonlinear processing function selected based on the characteristics of the low-band signal 122. Using the selected nonlinear processing function can increase the correlation between the synthetic high-band signal and the high-band signal 124 under both the voiced and unvoiced conditions.

2, a particular embodiment of a decoder system operable to perform harmonic bandwidth extension of an audio signal is shown and generally designated 200. Encoder system 100 and decoder system 200 may be included in a single device or separate devices.

In certain embodiments, the decoder system 200 may be integrated into an encoding (or decoding) system or device, such as a wireless phone or a codec/decoder (CODEC). In other embodiments, the decoder system 200 may be integrated into a set-top box, a music player, a video player, an entertainment unit, a navigation device, a communication device, a personal digital assistant (PDA), a fixed location data unit, or a computer.

It should be noted that in the following description, various functions performed by the decoder system 200 of FIG. 2 are described as being performed by certain components or modules. This division of components and modules is for illustrative purposes only and is not to be considered limiting. In an alternative embodiment, the functions performed by a particular component or module may be divided among multiple components or modules. Furthermore, in an alternative embodiment, two or more components or modules of FIG. 2 may be integrated into a single component or module. Each component or module illustrated in FIG. 2 may be implemented using hardware (e.g., a field programmable gate array (FPGA) device, an application-specific integrated circuit (ASIC), a digital signal processor (DSP), a controller, etc.), software (e.g., instructions executable by a processor), or any combination thereof.

The decoder system 200 includes a low-band decoder 208 coupled to the signal generator 112 , the filter 114 , the mixer 116 , a high-band signal generator 216 , and a synthesis filter bank 210 .

During operation, low-band decoder 208 can receive low-band data 268. Low-band data 268 can correspond to the output bit stream produced by the encoder system 100 of Fig. 1. For example, a receiver at decoder system 200 can receive (for example, via wired, wireless or optical channel) input bit stream. The input bit stream can correspond to the output bit stream produced by encoder system 100. Receiver can provide the input bit stream to demultiplexer (DEMUX). DEMUX can produce low-band data 268 and adjustment parameters from the input bit stream. In a particular embodiment, DEMUX can extract harmonics factors from the input bit stream. DEMUX can provide low-band data 268 to low-band decoder 208.

The low-band decoder 208 may extract low-band parameters from the low-band data 268. The low-band parameters may correspond to the low-band parameters 168 of FIG1 . The low-band decoder 208 may generate a synthesized low-band signal 222 based on the low-band parameters. The synthesized low-band signal 222 may be similar to the low-band signal 122 of FIG1 .

Signal generator 112 can receive synthetic low-band signal 222 from low-band decoder 208. Signal generator 112 can produce the third extended signal 274 based on synthetic low-band signal 222, as described with reference to FIG1. For example, function selector 180 can select nonlinear processing function from a plurality of available nonlinear processing functions 218 based on synthetic low-band signal 222. Signal generator can expand synthetic low-band signal 222 and can apply selected nonlinear processing function to produce the third extended signal 274. The third extended signal 274 can be similar to the third extended signal 174 of FIG1. In a particular embodiment, function selector 180 selects nonlinear processing function based on received parameter. For example, decoder system 200 can receive the parameter of identification (for example, via index) specific nonlinear processing function, and described specific nonlinear processing function is applied to encode specific audio frame or audio frame sequence by encoder system (for example, encoder system 100). This parameter can be received for each frame or when the nonlinear processing function to be used changes.

The filter 114 may generate the second extended signal 272 by filtering the third extended signal 274, as described with reference to FIG 1. The second extended signal 272 may be similar to the second extended signal 172 of FIG 1 .

2 . Noise signal 276 may be similar to noise signal 176 of FIG. 1 and first extended signal 282 may be similar to first extended signal 182 of FIG.

Harmonicity decoder 206 can receive low-band data 268, adjustment parameter 178, received harmonicity factor (e.g., parameter) or a combination thereof. For example, harmonicity decoder 206 can receive low-band data 268, adjustment parameter 178, received harmonicity factor or a combination thereof from the DEMUX of decoder system 200. Harmonicity decoder 206 can generate harmonicity factor 270 based on low-band data 268, adjustment parameter 178, received harmonicity factor or a combination thereof. For example, harmonicity decoder 206 can extract low-band parameters from low-band data 268. As another example, harmonicity decoder 206 can extract high-band parameters from adjustment parameter 178. Harmonicity decoder 206 can generate calculated harmonicity factor based on low-band parameters, high-band parameters or both, as described with reference to FIG.

Harmonicity decoder 206 can be set to calculated harmonicity factor or received harmonicity factor with harmonicity factor 270.In a particular embodiment, harmonicity decoder 206 can be set to calculated harmonicity factor with harmonicity factor 270 in response to the error that detects in the received harmonicity factor.Harmonicity decoder 206 can be responded to and determine that the difference between received harmonicity factor and the calculated harmonicity factor satisfies specific threshold value and detects error.Harmonicity decoder 206 can be provided to frequency mixer 116 with harmonicity factor 270.Frequency mixer 116 can be provided to high frequency band signal generator 216 with first expansion signal 282.

High-frequency band signal generator 216 can produce synthetic high-frequency band signal 224 based on at least one in adjustment parameter 178 and the first extended signal 282.For example, high-frequency band signal generator 216 can apply adjustment parameter 178 to first extended signal 282 to produce synthetic high-frequency band signal 224.For illustration, high-frequency band signal generator 216 can come the first extended signal 282 in proportion by the factor associated with at least one in adjustment parameter 178.In a particular embodiment, one or more in adjustment parameter 178 can correspond to gain adjustment parameter.High-frequency band signal generator 216 can apply gain adjustment parameter to first extended signal 282 to produce synthetic high-frequency band signal 224.Composition filter group 210 can receive synthetic high-frequency band signal 224 and synthetic low-frequency band signal 222.Output audio signal 278 can be provided to loudspeaker (or other output device) and/or through storage by composition filter group 210.

Decoder system 200 can use the non-linear processing function of the low-frequency band parameter selection of the characteristic of the low-frequency band part of the input signal that receives based on the indication encoder place to realize and produce synthetic high-frequency band signal at the decoder place.Use selected non-linear processing function to produce synthetic high-frequency band signal and can improve the dependency between the high-frequency band part of synthetic high-frequency band signal and the input signal under both voiced situation and silent situation.

3 , a particular embodiment of a system operable to perform harmonic bandwidth extension of an audio signal is shown and generally designated 300 .

In certain embodiments, system 300 (or portions thereof) may be integrated into an encoding (or decoding) system or device, such as a wireless telephone or a codec/decoder (CODEC). In other embodiments, system 300 (or portions thereof) may be integrated into a set-top box, a music player, a video player, an entertainment unit, a navigation device, a communication device, a personal digital assistant (PDA), a fixed location data unit, or a computer.

It should be noted that in the following description, the various functions performed by the system 300 of Figure 3 are described as being performed by certain components or modules. This division of components and modules is for illustrative purposes only and is not to be considered restrictive. In alternative embodiments, the functions performed by a particular component or module may be divided among multiple components or modules. In addition, in alternative embodiments, two or more components or modules of Figure 3 may be integrated into a single component or module. Each component or module illustrated in Figure 3 may be implemented using hardware (e.g., a field programmable gate array (FPGA) device, an application-specific integrated circuit (ASIC), a digital signal processor (DSP), a controller, etc.), software (e.g., instructions executable by a processor), or any combination thereof.

System 300 includes analysis filterbank 110 , lowband encoder 108 , harmonicity estimator 106 , parameter estimator 190 , and decoder system 200 .

During operation, the analysis filterbank 110 may receive an input audio signal 102. The analysis filterbank 110 may separate the input audio signal 102 into at least a low-band signal 122 and a high-band signal 124.

The lowband encoder 108 may receive the lowband signal 122 from the analysis filterbank 110. The lowband encoder 108 may determine lowband parameters 168 based on the lowband signal 122, as described with reference to FIG1. The lowband encoder 108 may provide the lowband parameters 168 to the decoder system 200.

The harmonicity estimator 106 may receive the high-band signal 124 and may generate a harmonicity factor 170 based on the high-band signal 124. For example, the harmonicity estimator 106 may generate the harmonicity factor 170 based on a high-band parameter indicating a characteristic of the high-band signal 124, as described with reference to FIG1 . The harmonicity estimator 106 may provide the harmonicity factor 170 to the decoder system 200.

The parameter estimator 190 may generate adjustment parameters 178 based on the high-band signal 124. For example, the adjustment parameters 178 may correspond to high-band parameters indicating characteristics of the high-band signal 124. The parameter estimator 190 may provide the adjustment parameters 178 to the decoder system 200. The decoder system 200 may generate a synthesized high-band signal 224 based on the adjustment parameters 178, the low-band parameters 168, the harmonicity factors 170, or a combination thereof, as described with reference to FIG.

System 300 uses the nonlinear processing function that selects based on the characteristic of synthetic low-frequency band signal and realizes and produces high-frequency band signal at the decoder place.System 300 can produce adjustment parameter 178 based on high-frequency band signal 124 and not based on the extended version of low-frequency band signal.In a specific embodiment, system 300 can be used for expanding input audio signal 102 and the processing time that extension signal is mixed with noise signal and produces adjustment parameter 178 faster than encoder system 100 by saving.

4, a flow chart of a particular embodiment of a method of performing harmonic bandwidth extension of an audio signal is shown and generally designated 400. The method 400 may be performed by the encoder system 100 of FIG.

Method 400 may include, at a device, separating an input audio signal into at least a low-band signal and a high-band signal (at 402). The low-band signal may correspond to a low-band frequency range and the high-band signal may correspond to a high-band frequency range. For example, the analysis filter bank 110 of FIG. 1 may separate the input audio signal 102 into at least a low-band signal 122 and a high-band signal 124, as described with reference to FIG. The low-band signal 122 may correspond to a low-band frequency range (e.g., 50 hertz (Hz) to 7 kilohertz (kHz)) and the high-band signal 124 may correspond to a high-band frequency range (e.g., 7 kHz to 16 kHz).

The method 400 may also include selecting a nonlinear processing function from the plurality of nonlinear processing functions at 404. For example, the function selector 180 of FIG. 1 may select a particular nonlinear processing function from the plurality of available nonlinear processing functions 118, as described with reference to FIG.

Method 400 may further include generating a first extended signal based on the low-band signal and the nonlinear processing function at 406. For example, mixer 116 of FIG. 1 may generate first extended signal 182 based on low-band signal 122 and the selected nonlinear processing function, as described with reference to FIG.

Method 400 may also include generating at least one adjustment parameter based on at least one of the first extended signal or the high-band signal at 408. For example, parameter adjuster 190 may generate adjustment parameter 178 based on at least one of the first extended signal 182 or the high-band signal 124, as described with reference to FIG.

Method 400 can use the non-linear processing function of characteristic selection based on low-frequency band signal 122 to realize and produce synthetic high-frequency band signal (for example, first extended signal 182) at encoder place.Use selected non-linear processing function to increase the correlation between synthetic high-frequency band signal and the high-frequency band signal 124 under voiced situation and silent situation.

In certain embodiments, the method 400 of FIG. 4 may be implemented via hardware (e.g., a field programmable gate array (FPGA) device, an application specific integrated circuit (ASIC), etc.) of a processing unit (e.g., a central processing unit (CPU), a digital signal processor (DSP), or a controller) or via firmware, or any combination thereof. As an example, the method 400 of FIG. 4 may be performed by a processor executing instructions (as described with respect to FIG. 6 ).

5, a flow chart of a particular embodiment of a method of performing harmonic bandwidth extension of an audio signal is shown and generally designated 500. Method 500 may be performed by decoder system 200 of FIG.

The method 500 may include receiving, at a device, low-band data corresponding to at least a low-band signal of an input audio signal at 502. For example, a DEMUX of the decoder system 200 may receive an input bit stream via a receiver, as described with reference to FIG2. As another example, the low-band decoder 208 may receive the low-band data 268, as described with reference to FIG2.

The method 500 may also include decoding the low-band data to generate a synthesized low-band audio signal at 504. For example, the low-band decoder 208 may decode the low-band data 268 to generate the synthesized low-band signal 222, as described with reference to FIG.

The method 500 may further include selecting a nonlinear processing function from the plurality of nonlinear processing functions at 506. For example, the function selector 180 may select a particular nonlinear processing function from the plurality of available nonlinear processing functions 118, as described with reference to FIG.

Method 500 may also include generating a synthesized high-band audio signal based on the synthesized low-band audio signal and the nonlinear processing function at 508. For example, the high-band signal generator 216 may generate a synthesized high-band signal 224 based on the synthesized low-band signal 222 and the selected nonlinear processing function, as described with reference to FIG.

Method 500 can use the non-linear processing function of the low-frequency band parameter selection of the characteristic of the low-frequency band part of the input signal that receives at the encoder place to realize and produce synthetic high-frequency band signal at the decoder place.Use selected non-linear processing function to produce synthetic high-frequency band signal and can improve the dependency between the high-frequency band part of synthetic high-frequency band signal and the input signal under voiced situation and silent situation.

In certain embodiments, the method 500 of FIG5 may be implemented via hardware (e.g., a field programmable gate array (FPGA) device, an application specific integrated circuit (ASIC), etc.) of a processing unit (e.g., a central processing unit (CPU), a digital signal processor (DSP), or a controller) or via firmware, or any combination thereof. As an example, the method 500 of FIG5 may be performed by a processor executing instructions (as described with respect to FIG6 ).

6 , a block diagram of a particular illustrative embodiment of a wireless communication device is depicted and generally designated 600. Device 600 includes a processor 610 (e.g., a central processing unit (CPU), a digital signal processor (DSP), etc.) coupled to a memory 632. Memory 632 may include instructions 660 executed by processor 610. Processor 610 may also include a coder/decoder (CODEC) 634, as shown. CODEC 634 may perform the methods and procedures disclosed herein, such as method 400 of FIG. 4 , method 500 of FIG. 5 , or both, and/or instructions 660 may be executed by processor 610 to perform the methods and procedures disclosed herein, such as method 400 of FIG. 4 , method 500 of FIG. 5 , or both.

CODEC 634 may comprise an encoder 690 and a decoder 692. Encoder 690 may comprise one or more of analysis filter bank 110, harmonicity estimator 106, low-band encoder 108, mixer 116, signal generator 112, filter 114 and parameter estimator 190, as shown. Decoder 692 may comprise one or more of composite filter bank 210, harmonicity decoder 206, low-band decoder 208, high-band signal generator 216, mixer 116 and filter 114, as shown. In an alternative embodiment, encoder 690 and decoder 692 may reside in a plurality of processors or in its part. For example, device 600 may comprise a plurality of processors (e.g., DSP and application processor), and encoder 690 and decoder 692 or its components may be included in some or all of a plurality of processors.

The analysis filterbank 110, the harmonicity estimator 106, the low-band encoder 108, the mixer 116, the signal generator 112, the filter 114, the parameter estimator 190, the synthesis filterbank 210, the harmonicity decoder 206, the low-band decoder 208, the high-band signal generator 216, or a combination thereof may be implemented via dedicated hardware (e.g., circuitry), via a processor executing instructions to perform one or more tasks, or a combination thereof. As an example, these instructions may be stored in a memory device such as a random access memory (RAM), a magnetoresistive random access memory (MRAM), a spin torque transfer MRAM (STT-MRAM), a flash memory, a read-only memory (ROM), a programmable read-only memory (PROM), a solid-state memory, an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), a cache, a hard disk, a removable disk, or a compact disc read-only memory (CD-ROM).

6 also shows a display controller 626 coupled to the processor 610 and to a display 628. A speaker 636 and a microphone 638 may be coupled to the device 600. For example, the microphone 638 may generate the input audio signal 102 of FIG. 1 , and the device 600 may generate an output bit stream for transmission to a receiver based on the input audio signal 102, as described with reference to FIG. 1 . For example, the output bit stream may be transmitted by a transmitter via the processor 610, the wireless controller 640, and the antenna 642. As another example, the speaker 636 may be used to output a signal reconstructed by the device 600 from the input bit stream received by the receiver (e.g., via the wireless controller 640 and the antenna 642), as described with reference to FIG.

In a particular embodiment, the processor 610, display controller 626, memory 632, and wireless controller 640 are included in a system-in-package or system-on-a-chip device (e.g., a mobile station modem (MSM)) 622. In a particular embodiment, an input device 630 (e.g., a touch screen and/or keypad) and a power supply 644 are coupled to the system-on-a-chip device 622. Furthermore, in a particular embodiment, as illustrated in FIG6 , the display 628, input device 630, speaker 636, microphone 638, antenna 642, and power supply 644 are external to the system-on-a-chip device 622. Each of the display 628, input device 630, speaker 636, microphone 638, antenna 642, and power supply 644 can be coupled to a component of the system-on-a-chip device 622, such as an interface or controller.

In conjunction with described embodiment, first device may comprise the device for dividing input audio signal into at least low-band signal and high-band signal, for example analysis filter bank 110, one or more other devices or circuits configured to separate audio signal, or its any combination.Low-band signal may correspond to low-band frequency range and high-band signal may correspond to high-band frequency range.Described device may also comprise the device for selecting the nonlinear processing function in a plurality of nonlinear processing functions, for example function selector 180, one or more other devices or circuits configured to select nonlinear processing function from a plurality of nonlinear processing functions, or its any combination.Described device may further comprise the first device for generating the first extended signal based on low-band signal and nonlinear processing function, for example mixer 116, one or more other devices or circuits configured to generate signal based on low-band signal and nonlinear processing function, or its any combination.Described device may also comprise the second device for generating at least one adjustment parameter based on the first extended signal, high-band signal or both, for example parameter estimator 190, one or more other devices or circuits configured to generate at least one adjustment parameter based on extended signal and/or high-band signal, or its any combination.

In conjunction with described embodiment, second device may comprise the device for receiving the low-frequency band data of at least the low-frequency band signal corresponding to the input audio signal, for example the component of decoder system 200 or the component (for example being coupled to decoder system 200, receiver), be configured to receive one or more other devices or circuit of the low-frequency band data of the low-frequency band signal corresponding to the input audio signal, or its any combination.Described device may also comprise the device for decoding low-frequency band data to produce the synthetic low-frequency band audio signal, for example low-frequency band decoder 208, be configured to decode low-frequency band data to produce one or more other devices or circuit of synthetic low-frequency band audio signal, or its any combination.Described device may further comprise the device for selecting the nonlinear processing function in a plurality of nonlinear processing functions, for example function selector 180, be configured to select one or more other devices or circuit of the nonlinear processing function in a plurality of nonlinear processing functions, or its any combination. The device may also include a device for generating a synthetic high-band audio signal based on the synthetic low-band audio signal and the non-linear processing function, such as a high-band signal generator 216, one or more other devices or circuits configured to generate a synthetic high-band audio signal based on the synthetic low-band audio signal and the non-linear processing function, or any combination thereof.

Those skilled in the art will further appreciate that the various illustrative logical blocks, configurations, modules, circuits, and algorithm steps described in conjunction with the embodiments disclosed herein may be implemented as electronic hardware, computer software executed by a processing device such as a hardware processor, or a combination of both. Various illustrative components, blocks, configurations, modules, circuits, and steps are generally described above in terms of functionality. Whether this functionality is implemented as hardware or executable software depends on the specific application and the design constraints imposed on the overall system. For each specific application, those skilled in the art may implement the described functionality in varying ways, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.

The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of both. The software module may reside in a memory device, such as random access memory (RAM), magnetoresistive random access memory (MRAM), spin torque transfer MRAM (STT-MRAM), flash memory, read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), cache, hard disk, removable disk, or compact disc read-only memory (CD-ROM). Exemplary memory devices are coupled to the processor so that the processor can read information from and write information to the memory device. Alternatively, the memory device may be integral to the processor. The processor and storage medium may reside in an application-specific integrated circuit (ASIC). The ASIC may reside in a computing device or user terminal. Alternatively, the processor and storage medium may reside as discrete components in the computing device or user terminal.

The foregoing description of the disclosed embodiments is provided to enable one skilled in the art to make or use the disclosed embodiments. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the principles defined herein may be applied to other embodiments without departing from the scope of the invention. Therefore, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope possible consistent with the principles and novel features as defined by the following claims.

Claims (59)

1. A method for harmonic bandwidth extension of an audio signal, comprising: At the device, the input audio signal is divided into at least a low-frequency band signal and a high-frequency band signal, wherein the low-frequency band signal corresponds to a low-frequency band frequency range and the high-frequency band signal corresponds to a high-frequency band frequency range. Determine the characteristics of low-frequency signals; Based on the aforementioned characteristics, a nonlinear processing function is selected from among multiple nonlinear processing functions; A first extended signal is generated based on the low-frequency band signal and the nonlinear processing function; and At least one adjustment parameter is generated based on the first extended signal, the high-frequency band signal, or both. 2. The method of claim 1, wherein the nonlinear processing function is selected after the input audio signal is received at the device, wherein the first extended signal is generated via a mixed noise signal and a second extended signal, and wherein the at least one adjustment parameter is determined based on the first extended signal and the high-frequency band signal. 3. The method of claim 2, wherein the noise signal of the first proportion and the second extended signal of the second proportion are mixed, and wherein the first proportion and the second proportion are determined based on the harmonicity of at least one of the low-frequency signal, the high-frequency signal, or the input audio signal. 4. The method of claim 3, further comprising: The harmonicity is determined based on the estimation of the periodicity of the input audio signal in the audio frame. The nonlinear processing function is selected in response to receiving the input audio signal. 5. The method of claim 2, further comprising: The second extended signal is generated by filtering the third extended signal, wherein the bandwidth of the second extended signal corresponds to the high-frequency band range. 6. The method of claim 5, further comprising: The third extended signal is generated by applying the nonlinear processing function to the low-frequency band signal, wherein the nonlinear processing function is selected on a frame-by-frame basis. 7. The method of claim 2, wherein the second extended signal is generated by applying a linear transformation to the third extended signal and selecting transformation coefficients corresponding to the high-frequency band range. 8. The method according to claim 7, wherein: The nonlinear processing function is selected by a function selector based on the characteristics of the low-frequency signal or a determined value of the characteristics of the low-frequency signal, wherein the linear transformation corresponds to the discrete cosine transform. 9. The method of claim 1, further comprising: In response to determining that the at least one adjustment parameter satisfies a first condition, a first nonlinear processing function is selected from the plurality of nonlinear processing functions. 10. The method of claim 1, wherein the nonlinear processing function is selected from the following: The first nonlinear processing function corresponding to the low-order power function among the plurality of nonlinear processing functions, and The second nonlinear processing function among the plurality of nonlinear processing functions corresponds to the higher-order power function. 11. The method of claim 1, further comprising: The input audio signal is divided into at least the low-frequency band signal and the high-frequency band signal using an analytical filter bank; and Determine the parameters associated with the frames of the input audio signal. Wherein, the characteristic is the audio characteristic of the low-frequency band signal, and the at least one adjustment parameter corresponds to at least one gain adjustment parameter associated with the high-frequency band signal, and The parameters associated with the frame include one of the following: a decoding mode selected to encode the low-frequency band signal, the periodicity of the frame, the amount of non-periodic noise in the frame, or the spectral tilt corresponding to the frame. 12. A method for harmonic bandwidth extension of an audio signal, comprising: At the device, low-frequency data corresponding to at least a low-frequency signal of the input audio signal is received; Decode the low-frequency data to generate a synthetic low-frequency audio signal; Determine the characteristics of the low-frequency band signal; Based on the aforementioned characteristics, a nonlinear processing function is selected from among multiple nonlinear processing functions; and A synthesized high-frequency audio signal is generated based on the synthesized low-frequency audio signal and the nonlinear processing function. 13. The method of claim 12, further comprising generating an output audio signal by combining the synthesized low-frequency audio signal and the synthesized high-frequency audio signal, wherein the nonlinear processing function is selected based on the synthesized low-frequency audio signal, and wherein a first bandwidth of the output audio signal is greater than a second bandwidth of the synthesized low-frequency audio signal. 14. The method of claim 12, further comprising generating a first extended signal via mixing a noise signal and a second extended signal, wherein the synthesized high-frequency audio signal is generated based on the first extended signal and at least one adjustment parameter, wherein a first proportion of the second extended signal and a second proportion of the noise signal are mixed, and wherein the first proportion and the second proportion are determined based on at least one of a received harmonic parameter or the low-frequency data. 15. The method of claim 12, wherein the synthesized high-frequency band audio signal is generated by scaling a first extended signal by a factor associated with at least one adjustment parameter. 16. The method of claim 12, further comprising generating a first extended signal based on a second extended signal and a third extended signal, wherein the second extended signal corresponds to a high-frequency band range. 17. The method of claim 12, further comprising generating a first extended signal based on a second extended signal, wherein the second extended signal is generated via: The third extended signal is generated by applying a linear transform to the discrete cosine transform, and the third extended signal is based on the synthesized low-frequency audio signal and the nonlinear processing function; and Choose the transformation coefficients that correspond to the high-frequency band. 18. The method of claim 12, further comprising selecting the nonlinear processing function based on parameters received at the device on a frame-by-frame basis. 19. The method of claim 12, wherein the receiving, decoding, determining, selecting, and generating are performed within the apparatus, and wherein the apparatus includes a mobile communication device. 20. The method of claim 12, wherein the receiving, decoding, determining, selecting, and generating are performed within a fixed-location data unit. 21. A device for harmonic bandwidth extension of an audio signal, comprising: Memory, and A processor configured to perform the following operations: The input audio signal is divided into at least a low-frequency band signal and a high-frequency band signal, wherein the low-frequency band signal corresponds to a low-frequency band frequency range and the high-frequency band signal corresponds to a high-frequency band frequency range. Determine the characteristics of the low-frequency band signal; Based on the aforementioned characteristics, a nonlinear processing function is selected from among multiple nonlinear processing functions; A first extended signal is generated based on the low-frequency band signal and the nonlinear processing function; and At least one adjustment parameter is generated based on the first extended signal, the high-frequency band signal, or both. 22. The device of claim 21, wherein the nonlinear processing function is selected after the input audio signal is split into at least the low-frequency band signal and the high-frequency band signal, wherein the first extended signal is generated via a mixed noise signal and a second extended signal, and wherein the at least one adjustment parameter is determined based on the first extended signal and the high-frequency band signal. 23. The device of claim 22, wherein the noise signal of the first proportion and the second extended signal of the second proportion are mixed, and wherein the first proportion and the second proportion are determined based on the harmonicity of at least one of the low-frequency signal, the high-frequency signal, or the input audio signal. 24. The device of claim 23, wherein the processor is further configured to determine the harmonicity based on an estimate of the periodicity of the input audio signal in an audio frame. 25. The apparatus of claim 22, wherein the processor is further configured to generate the second extended signal by filtering the third extended signal, and wherein the bandwidth of the second extended signal corresponds to the high-frequency band range. 26. The device of claim 25, wherein the processor is further configured to generate the third extended signal by applying the nonlinear processing function to the low-frequency band signal. 27. The device of claim 22, wherein the input audio signal is divided into at least the low-frequency band signal and the high-frequency band signal using an analytical filter group, and wherein the second extended signal is generated by applying a linear transformation to the third extended signal and selecting transform coefficients corresponding to the frequency range of the high-frequency band, the linear transformation corresponding to the discrete cosine transform. 28. The device of claim 21, wherein the processor is further configured to determine parameters associated with frames of the input audio signal, wherein the nonlinear processing function is selected based on the parameters, wherein a first nonlinear processing function of the plurality of nonlinear processing functions is selected in response to determining that the parameters satisfy a first condition, and wherein a second nonlinear processing function of the plurality of nonlinear processing functions is selected in response to determining that the parameters satisfy a second condition. 29. The device of claim 28, wherein the parameter associated with the frame is one of a coding mode selected to encode the low-frequency signal, the periodicity of the frame, the amount of non-periodic noise in the frame, and the spectral tilt corresponding to the frame. 30. The device of claim 21, wherein the plurality of nonlinear processing functions include low-order power functions and high-order power functions, and wherein the at least one adjustment parameter corresponds to at least one gain adjustment parameter associated with the high-frequency band signal. 31. The device of claim 21, wherein the processor is integrated into the encoder system. 32. The device according to claim 21, further comprising: Antenna; and A receiver coupled to the antenna and configured to receive a signal corresponding to the input audio signal. 33. The device of claim 32, wherein the processor, the memory, the receiver, and the antenna are integrated into a mobile communication device. 34. The device of claim 32, wherein the processor, the memory, the receiver, and the antenna are integrated into a fixed-position data unit. 35. A device for harmonic bandwidth extension of an audio signal, comprising: Memory; and A processor configured to perform the following operations: Receive low-frequency data corresponding to at least a low-frequency signal of the input audio signal; Decode the low-frequency data to generate a synthetic low-frequency audio signal; Determine the characteristics of the low-frequency band signal; Based on the aforementioned characteristics, a nonlinear processing function is selected from among multiple nonlinear processing functions; and A synthesized high-frequency audio signal is generated based on the synthesized low-frequency audio signal and the nonlinear processing function. 36. The device of claim 35, wherein the processor is further configured to generate an output audio signal by combining the synthesized low-frequency audio signal and the synthesized high-frequency audio signal, and wherein a first bandwidth of the output audio signal is greater than a second bandwidth of the synthesized low-frequency audio signal. 37. The apparatus of claim 35, wherein the processor is further configured to generate a first extended signal via a mixed noise signal and a second extended signal, and wherein the synthesized high-frequency audio signal is generated based on the first extended signal and at least one adjustment parameter. 38. The device of claim 37, wherein the first proportion of the second extended signal and the second proportion of the noise signal are mixed, and wherein the first proportion and the second proportion are determined based on at least one of the received harmonic parameters or the low-frequency band data. 39. The device of claim 37, wherein the synthesized high-frequency band audio signal is generated by scaling the first extended signal by a factor associated with the at least one adjustment parameter. 40. The device of claim 37, wherein the processor is further configured to generate the second extended signal by filtering the third extended signal, and wherein the second extended signal corresponds to a high-frequency band range. 41. The device of claim 37, wherein the second extended signal is generated by applying a linear transformation to the third extended signal and selecting transformation coefficients corresponding to the high-frequency band. 42. The device of claim 41, wherein the linear transformation corresponds to the discrete cosine transform. 43. The device of claim 41, wherein the processor is further configured to generate the third extended signal based on the synthesized low-frequency audio signal and the nonlinear processing function. 44. The device of claim 35, wherein the processor is further configured to select the nonlinear processing function based on the received parameters or the low-frequency data. 45. The device of claim 35, wherein the processor is integrated into a mobile device including a decoder system. 46. A device for harmonic bandwidth extension of an audio signal, comprising: A device for dividing an input audio signal into at least a low-frequency band signal and a high-frequency band signal, wherein the low-frequency band signal corresponds to a low-frequency band frequency range and the high-frequency band signal corresponds to a high-frequency band frequency range; A device for determining the characteristics of the low-frequency band signal; A means for selecting a nonlinear processing function from a plurality of nonlinear processing functions based on the aforementioned characteristics; A first device for generating a first extended signal based on the low-frequency band signal and the nonlinear processing function; and A second means for generating at least one adjustment parameter based on the first extended signal, the high-frequency band signal, or both. 47. The device of claim 46, wherein the means for selection is configured to select the nonlinear processing function after receiving the input audio signal at the means for separation, wherein the first extended signal is generated via a mixed noise signal and a second extended signal, and wherein the at least one adjustment parameter is determined based on the first extended signal and the high-frequency band signal. 48. The device of claim 47, wherein the noise signal of the first proportion and the second extended signal of the second proportion are mixed, and wherein the first proportion and the second proportion are determined based on the harmonicity of at least one of the low-frequency signal, the high-frequency signal, or the input audio signal. 49. The device of claim 46, wherein the means for determining, the means for selecting, the first means for generating, and the second means for generating are integrated into the mobile device. 50. A device for harmonic bandwidth extension of an audio signal, comprising: A means for receiving low-frequency data corresponding to at least a low-frequency signal of an input audio signal; A means for decoding the low-frequency data to generate a synthetic low-frequency audio signal; A device for determining the characteristics of the low-frequency band signal; A means for selecting a nonlinear processing function from a plurality of nonlinear processing functions based on the aforementioned characteristics; and Apparatus for generating a synthesized high-frequency audio signal based on the synthesized low-frequency audio signal and the nonlinear processing function. 51. The device of claim 50, wherein the low-frequency data indicates the characteristics of the low-frequency signal. 52. The apparatus of claim 50, wherein the synthesized high-frequency band audio signal is generated by scaling a first extended signal by a factor associated with the at least one adjustment parameter. 53. The device of claim 50, wherein the means for determining, the means for selecting, and the means for generating are integrated into the communication mobile device. 54. The device of claim 50, wherein the means for determining, the means for selecting, and the means for generating are integrated into a fixed-position data unit. 55. A computer-readable storage device storing instructions that, when executed by a processor, cause the processor to perform operations comprising: The input audio signal is divided into at least a low-frequency band signal and a high-frequency band signal, wherein the low-frequency band signal corresponds to a low-frequency band frequency range and the high-frequency band signal corresponds to a high-frequency band frequency range. Determine the characteristics of the low-frequency band signal; Based on the aforementioned characteristics, a nonlinear processing function is selected from among multiple nonlinear processing functions; A first extended signal is generated based on the low-frequency band signal and the nonlinear processing function; and At least one adjustment parameter is generated based on the first extended signal, the high-frequency band signal, or both. 56. The computer-readable storage device of claim 55, wherein the nonlinear processing function is selected after the input audio signal is split into at least the low-frequency band signal and the high-frequency band signal, wherein the first extended signal is generated via a mixed noise signal and a second extended signal, and wherein the at least one adjustment parameter is determined based on the first extended signal and the high-frequency band signal. 57. The computer-readable storage device of claim 56, wherein the operation further comprises: The second extended signal is generated by filtering the third extended signal, wherein the bandwidth of the second extended signal corresponds to the high-frequency band range; and The third extended signal is generated by applying the nonlinear processing function to the low-frequency signal. 58. A computer-readable storage device storing instructions that, when executed by a processor, cause the processor to perform operations comprising: Receive low-frequency data corresponding to at least a low-frequency signal of the input audio signal; Decode the low-frequency data to generate a synthetic low-frequency audio signal; Determine the characteristics of the low-frequency band signal; Based on the aforementioned characteristics, a nonlinear processing function is selected from among multiple nonlinear processing functions; and A synthesized high-frequency audio signal is generated based on the synthesized low-frequency audio signal and the nonlinear processing function. 59. The computer-readable storage device of claim 58, wherein the operation further comprises determining parameters associated with frames of the input audio signal, wherein the nonlinear processing function is selected based on the parameters.