HK1227164B - High band excitation signal generation - Google Patents

Description

High-band excitation signal generation

Priority Declaration

This application claims priority to U.S. Application No. 14/265,693, filed April 30, 2014, entitled “HIGH BAND EXCITATION SIGNALGENERATION,” the contents of which are incorporated by reference in their entirety.

Technical Field

The present invention generally relates to high-band excitation signal generation.

Background Art

Advances in technology have led to 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 of these 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.

Transmitting speech by digital technology is common, especially in long-distance and digital radiotelephony applications. If the speech is transmitted by sampling and digitizing, a data rate of approximately 64 kilobits per second (kbps) can be used to achieve the speech quality of analog telephony. Compression techniques can be used to reduce the amount of information sent over the channel while maintaining the perceived quality of the reconstructed speech. By using speech analysis at the receiver, followed by decoding, transmission, and resynthesis, a significant reduction in data rate can be achieved.

Devices for compressing speech can be used in many areas of telecommunications. For example, wireless communications have many applications, including, for example, cordless telephony, paging, wireless local loops, wireless telephony (e.g., cellular and Personal Communications Service (PCS) telephone systems), mobile Internet Protocol (IP) telephony, and satellite communication systems. A particular application is wireless telephony for mobile users.

Various air interfaces have been developed for wireless communication systems, including, for example, frequency division multiple access (FDMA), time division multiple access (TDMA), code division multiple access (CDMA), and time division synchronous CDMA (TD-SCDMA). Various domestic and international standards have been established in conjunction with these air interfaces, including, for example, Advanced Mobile Phone Service (AMPS), Global System for Mobile Communications (GSM), and Interim Standard 95 (IS-95). An exemplary wireless telephone communication system is a code division multiple access (CDMA) system. The IS-95 standard and its derivatives (IS-95A, ANSI J-STD-008, and IS-95B) (collectively referred to herein as IS-95) were promulgated by the Telecommunications Industry Association (TIA) and other recognized standards bodies to specify the use of the CDMA air interface for cellular or PCS telephone communication systems.

The IS-95 standard subsequently evolved into "3G" systems such as cdma2000 and WCDMA, which provide higher capacity and high-speed packet data services. Two variations of cdma2000 are represented by documents IS-2000 (cdma2000 1xRTT) and IS-856 (cdma2000 1xEV-DO), published by the International Telecommunication Union (TIA). The cdma2000 1xRTT communication system provides a peak data rate of 153 kbps, while the cdma2000 1xEV-DO communication system defines a set of data rates ranging from 38.4 kbps to 2.4 Mbps. The WCDMA standard is embodied in the Third Generation Partnership Project (3GPP) specifications 3G TS 25.211, 3G TS 25.212, 3G TS 25.213, and 3G TS 25.214. The International Mobile Telecommunications (IMT) Advanced specifications set forth the "4G" standard. For high-mobility communications (e.g., from trains and cars), the IMT Advanced specifications set a peak data rate of 100 megabits per second (Mbit/s) for 4G services, and for low-mobility communications (e.g., from pedestrians and stationary users), the IMT Advanced specifications set a peak data rate of gigabits per second (Gbit/s).

Devices that use techniques for compressing speech by extracting parameters related to a generative model of human speech are called speech decoders. A speech decoder may include an encoder and a decoder. The encoder divides the incoming speech signal into time blocks, or analysis frames. The duration of each time segment (or "frame") may be chosen to be short enough so that the spectral envelope of the signal can be expected to remain relatively static. For example, the frame length may be 20 milliseconds, which corresponds to 160 samples at an 8 kilohertz (kHz) sampling rate, but any frame length or sampling rate deemed appropriate for a particular application may be used.

The encoder analyzes the incoming speech frames to extract certain relevant parameters and then quantizes the parameters into a binary representation (e.g., a set of bits or binary data packets). The data packets are transmitted via a communication channel (i.e., a wired and/or wireless network connection) to a receiver and decoder. The decoder processes the data packets, dequantizes the processed data packets to generate parameters, and resynthesizes the speech frames using the dequantized parameters.

The function of a speech decoder is to compress a digitized speech signal into a low bit rate signal by removing the natural redundancy inherent in speech. Digital compression can be achieved by representing the input speech frame with a set of parameters and using quantization to represent the parameters with a set of bits. If the input speech frame has a bit count _Ni and the data packet produced by the speech decoder has a bit count _No , then the compression factor achieved by the speech decoder is _Cr = _Ni / _No . The challenge is to preserve high speech quality of the decoded speech while achieving the target compression factor. The performance of the speech decoder depends on: (1) how well the speech model or the combination of the analysis and synthesis processes described above performs, and (2) how well the parameter quantization process performs at the target bit rate of _{No bits} per frame. Therefore, the goal of the speech model is to capture the essence of the speech signal or the target speech quality using a small set of parameters for each frame.

Speech decoders typically use a set of parameters (including vectors) to describe speech signals. A good parameter set ideally provides low system bandwidth for perceptually accurate reconstruction of speech signals. Pitch, signal power, spectral envelope (or formants), amplitude, and phase spectrum are examples of speech decoding parameters.

The speech decoder can be implemented as a time-domain decoder, which attempts to capture the time-domain speech waveform by encoding small speech segments (e.g., 5 millisecond (ms) subframes) at a time using high-time resolution processing. For each subframe, a high-precision representation from the codebook space is found with the help of a search algorithm. Alternatively, the speech decoder can be implemented as a frequency-domain decoder, which attempts to capture the short-term speech spectrum of the input speech frame through parameter set (analysis) and using a corresponding synthesis process to regenerate the speech waveform from the spectral parameters. The parameter quantizer maintains the parameters by representing them with stored representations of code vectors according to known quantization techniques.

One time-domain speech decoder is a code-excited linear prediction (CELP) decoder. In a CELP decoder, short-term correlations or redundancies in the speech signal are removed by linear prediction (LP) analysis, which finds the coefficients of a short-term formant filter. The short-term prediction filter is applied to the incoming speech frame to generate an LP residual signal, which is further modeled and quantized using the long-term prediction filter parameters and a subsequent random codebook. CELP decoding thus divides the task of encoding the time-domain speech waveform into the separate tasks of encoding the LP short-term filter coefficients and encoding the LP residual. Time-domain decoding can be performed at a fixed rate (i.e., using the same number of bits, _No, for each frame) or a variable rate (where different bit rates are used for different types of frame content). Variable-rate decoders attempt to use the number of bits required to encode the parameters to a level sufficient to achieve the target quality.

Time domain coders such as CELP coders can rely on a large number of bits per frame, N _, to maintain the accuracy of the time domain speech waveform. If the bit count per frame, N _, is relatively large (e.g., 8 kbps or higher), these coders can deliver excellent voice quality. At low bit rates (e.g., 4 kbps and lower), due to the limited number of available bits, time domain coders may not be able to maintain high quality and robust performance. At low bit rates, the limited codebook space reduces the waveform matching capabilities of time domain coders deployed in higher rate commercial applications. Therefore, many CELP coding system operations at low bit rates suffer from perceptually significant distortion characterized by noise.

An alternative to CELP coders at low bit rates is the "Noise Excited Linear Prediction" (NELP) coder, which operates on principles similar to CELP. NELP coders use a filtered pseudorandom noise signal to model speech rather than a codebook. Because NELP uses a simpler model for the coded speech, it achieves lower bit rates than CELP. NELP can be used to compress or represent unvoiced speech or silence.

Decoding systems operating at rates of approximately 2.4 kbps are typically parametric in nature. That is, they operate by transmitting parameters describing the pitch period and spectral envelope (or formants) of the speech signal at regular intervals. An example of such a parametric coder is the LP vocoder.

The LP vocoder models voiced speech signals with a single pulse per pitch period. This basic technique can be augmented to include transmission information about the spectral envelope and other matters. Although the LP vocoder provides generally reasonable performance, it can introduce perceptually significant distortion characterized by buzzing.

In recent years, decoders that are a hybrid of waveform and parametric coders have emerged. One example of these hybrid decoders is the prototype waveform interpolation (PWI) speech decoding system. PWI speech decoding systems may also be referred to as prototype pitch period (PPP) speech decoders. PWI speech decoding systems provide an efficient method for decoding voiced speech. The basic concept of PWI is to extract representative pitch cycles (prototype waveforms) at fixed time intervals, transmit their descriptions, and reconstruct the speech signal by interpolating between the prototype waveforms. The PWI method can operate on either the LP residual signal or the speech signal.

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 phones and Voice over Internet Protocol (VoIP), signal bandwidth can span a frequency range of 50 Hz to 7 kHz. Ultra-wideband (SWB) decoding technology supports bandwidth extension to approximately 16 kHz. Extending the signal bandwidth from 3.4 kHz for narrowband telephony to 16 kHz for SWB telephony improves the quality, intelligibility, and naturalness of signal reconstruction.

Wideband coding technology relates to the lower frequency portion (for example, 50Hz to 7kHz, also referred to as " low-frequency band ") of coding and transmitting signal. In order to improve decoding efficiency, the higher frequency portion (for example, 7kHz to 16kHz, also referred to as " high-frequency band ") of incomplete coding and transmitting signal can be used to generate high-frequency band signal. For example, can use nonlinear model (for example, absolute value function) to generate high-frequency band excitation signal based on low-frequency band residual. When low-frequency band residual is through sparse coding by pulse, the high-frequency band excitation signal generated by the residual of sparse coding can cause artifact in the unvoiced region of high-frequency band.

Summary of the Invention

Disclose the system and method for high frequency band excitation signal generation.Audio decoder can receive the audio signal by audio coder coding at transmitting device place.Audio decoder can determine the voiced sound classification (for example, strong voiced sound, weak voiced sound, weak voiceless sound, strong voiceless sound) of specific audio signal.For example, the scope of specific audio signal can be strong voiced sound (for example, voice signal) to strong voiceless sound (for example, noise signal).Audio decoder can be based on the amount of the envelope of the representation of voiced sound classification control input signal.

The amount of control envelope can comprise the characteristic (for example, shape, frequency range, gain and/or magnitude) of control envelope.For example, audio decoder can generate low-band excitation signal from encoded audio signal, and can control the shape of the envelope of low-band excitation signal based on the classification of voiced sound.For example, audio coder can control the frequency range of envelope based on the cut-off frequency of the filter that is applied to low-band excitation signal.As another example, audio decoder can control the magnitude of envelope, the shape of envelope, the gain of envelope or its combination by one or more poles based on the classification of voiced sound adjustment linear prediction coding (LPC) coefficient.As another example, audio decoder can control the magnitude of envelope, the shape of envelope, the gain of envelope or its combination by the coefficient based on the classification of voiced sound adjustment filter, wherein said filter is applied to low-band excitation signal.

The audio codec can be based on the controlled amount modulation white noise signal of envelope.For example, compared when voiced sound is classified as strong voiceless, the modulated white noise signal can correspond to the low-band excitation signal more when voiced sound is classified as strong voiced.The audio decoder can generate the high-band excitation signal based on the modulated white noise signal.For example, the audio codec can expand the low-band excitation signal and can combine the modulated white noise signal and the low-band signal through extension to generate the high-band excitation signal.

In a particular embodiment, a method is included in a device to determine the voiced sound classification of an input signal. The input signal corresponds to an audio signal. The method also includes controlling the amount of an envelope of a representation of the input signal based on the voiced sound classification. The method further includes modulating a white noise signal based on the controlled amount of the envelope. The method includes generating a high-frequency band excitation signal based on the modulated white noise signal.

In another specific embodiment, a kind of apparatus comprises a voiced sound classifier, an envelope adjuster, a modulator and an output circuit.The voiced sound classifier is configured to determine the voiced sound classification of an input signal.The input signal corresponds to an audio signal.The envelope adjuster is configured to control the amount of the envelope of the representation of the input signal based on the voiced sound classification.The modulator is configured to modulate a white noise signal based on the controlled amount of the envelope.The output circuit is configured to generate a high frequency band excitation signal based on the modulated white noise signal.

In another specific embodiment, a computer-readable storage device stores instructions that, when executed by at least one processor, cause the at least one processor to determine the voiced sound classification of an input signal. Said instructions, when executed by at least one processor, further cause the at least one processor to control the amount of an envelope of a representation of the input signal based on the voiced sound classification, modulate a white noise signal based on the controlled amount of the envelope, and generate a high-frequency band excitation signal based on the modulated white noise signal.

Particular advantages provided by at least one of the disclosed embodiments include generating a smooth-sounding synthesized audio signal corresponding to an unvoiced audio signal. For example, the synthesized audio signal corresponding to the unvoiced audio signal may have few (or no) artifacts. Other aspects, advantages, and features of the present invention will become apparent after reviewing the application, which includes the following sections: a brief description of the drawings, detailed description, and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a diagram illustrating a particular embodiment of a system including an apparatus operable to perform high-band excitation signal generation;

Fig. 2 is the figure of the particular embodiment that explanation can be operated to carry out the decoder that high frequency band excitation signal generates;

Fig. 3 is the figure of the particular embodiment that explanation can be operated to carry out the encoder that high frequency band excitation signal generates;

Fig. 4 is a diagram illustrating a specific embodiment of the method for generating a high-frequency band excitation signal;

Fig. 5 is a diagram illustrating another embodiment of the method for generating a high-frequency band excitation signal;

Fig. 6 is a diagram illustrating another embodiment of the method for generating a high-frequency band excitation signal;

Fig. 7 is a diagram illustrating another embodiment of the method for generating a high-frequency band excitation signal;

FIG8 is a flow chart illustrating another embodiment of a method for generating a high-frequency band excitation signal; and

9 is a block diagram of an apparatus operable to perform high-band excitation signal generation according to the systems and methods of FIGS. 1-8 .

DETAILED DESCRIPTION

Principle described herein can be applicable to (for example) earphone, handset or other audio device that is configured to carry out high frequency band excitation signal generation.Unless by its context clearly limit, otherwise term " signal " is used in this article to indicate any one in its ordinary sense, comprises the state of the memory location (or the set of memory location) of expressing on electric wire, bus or other emission media.Unless by its context clearly limit, otherwise term " generate " is used in this article to indicate any one in its ordinary sense, for example calculate or produce in addition.Unless by its context clearly limit, otherwise term " calculate " is used in this article to indicate any one in its ordinary sense, for example calculate, evaluate, smoothen and/or select from a plurality of values.Unless by its context clearly limit, otherwise term " obtain " is used in this article to indicate any one in its ordinary sense, for example calculate, derive, receive (for example, from another component, piece or device) and/or retrieve (for example, from the array of memory register or storage component).

Unless expressly limited by its context, the term "generating" is used to indicate any of its ordinary meanings, such as calculating, generating, and/or providing. Unless expressly limited by its context, the term "providing" is used to indicate any of its ordinary meanings, such as calculating, generating, and/or producing. Unless expressly limited by its context, the term "coupling" is used to indicate a direct or indirect electrical or physical connection. If the connection is indirect, it should be fully understood by those skilled in the art that other blocks or components may exist between the "coupled" structures.

The term "configuration" may be used in reference to methods, apparatus/devices and/or systems as indicated by their specific context. Where the term "comprising" is used in this description and claims, it does not exclude other components or operations. The term "based on" (as in "A is based on B") is used to indicate any one of its usual meanings, including the following: (i) "based on at least" (e.g., "A is based on at least B"); and if appropriate in the specific context, (ii) "equal to" (e.g., "A is equal to B"). In the case where A is based on B including based on at least (i), this may include a configuration where A is coupled to B. Similarly, the term "responsive to" is used to indicate any one of its usual meanings, including "at least responsive to". The term "at least one" is used to indicate any one of its usual meanings, including "one or more". The term "at least two" is used to indicate any one of its usual meanings, including "two or more".

Unless the specific context indicates otherwise, the terms "apparatus" and "device" are used generically and interchangeably. Unless otherwise indicated, any disclosure of the operation of an apparatus having specific features is also expressly intended to disclose methods having similar features (and vice versa), and any disclosure of the operation of an apparatus according to a specific configuration is also expressly intended to disclose methods according to a similar configuration (and vice versa). Unless the specific context indicates otherwise, the terms "method," "process," "procedure," and "technique" are used generically and interchangeably. The terms "component" and "module" may be used to indicate a portion of a larger configuration. Any incorporation of a portion of a document by reference should also be understood to incorporate the definitions of the terms or variables referenced within that portion (where such definitions appear elsewhere in the document) and any figures referenced in the incorporated portion.

As used herein, the term "communication device" refers to an electronic device that can be used for voice and/or data communication via a wireless communication network. Examples of communication devices include cellular phones, personal digital assistants (PDAs), handheld devices, headsets, wireless modems, laptop computers, personal computers, etc.

With reference to figure 1, show the specific embodiment that comprises the system of the device that can operate to carry out high frequency band excitation signal generation, and it is designated as 100 usually.In a specific embodiment, one or more components of system 100 can be integrated into (for example, in wireless telephone or decoder/decoder (codec)) in decoding system or the equipment, be integrated into coding system or the equipment or in described two.In other embodiments, one or more components of system 100 can be integrated into in set-top box, music player, video player, entertainment unit, navigation device, communicator, personal digital assistant (PDA), fixed position data unit or the computer.

It should be noted that in the following description, the various functions performed by the system 100 of Figure 1 are described as being performed by certain components or modules. This division of components and modules is for illustration only. In alternative embodiments, the functions performed by a particular component or module may be divided into multiple components or modules. In addition, in alternative embodiments, two or more components or modules of Figure 1 may be integrated into a single component or module. Each component or module illustrated in Figure 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.

Although the illustrative embodiment described in Fig. 1 to 9 is described about the high-frequency band model, described high-frequency band model is similar to the model that is used for enhanced variable rate codec-narrowband-wideband (EVRC-NW), one or more in the illustrative embodiment can use any other high-frequency band model.Should be understood that, only for example, the use of any particular model is described.

System 100 comprises the mobile device 104 that communicates with first device 102 via network 120.Mobile device 104 can be coupled to microphone 146 or communicate with it.Mobile device 104 can comprise excitation signal generation module 122, high frequency band encoder 172, multiplexer (MUX) 174, transmitter 176 or its combination.First device 102 can be coupled to loudspeaker 142 or communicate with it.First device 102 can comprise excitation signal generation module 122 that is coupled to MUX 170 via high frequency band synthesizer 168.Excitation signal generation module 122 can comprise voiced sound classifier 160, envelope adjuster 162, modulator 164, output circuit 166 or its combination.

During operation, the mobile device 104 may receive an input signal 130 (e.g., a user voice signal of a first user 152, an unvoiced signal, or both). For example, the first user 152 may be in a voice call with the second user 154. The first user 152 may be using the mobile device 104, and the second user 154 may be using the first device 102 for the voice call. During the voice call, the first user 152 may speak into a microphone 146 coupled to the mobile device 104. The input signal 130 may correspond to the voice of the first user 152, background noise (e.g., music, street noise, another person's voice, etc.), or a combination thereof. The mobile device 104 may receive the input signal 130 via the microphone 146.

In a particular embodiment, the input signal 130 may be an ultra-wideband (SWB) signal containing data in a frequency range from approximately 50 hertz (Hz) to approximately 16 kilohertz (kHz). The low-band portion of the input signal 130 and the high-band portion of the input signal 130 may occupy non-overlapping frequency bands of 50 Hz to 7 kHz and 7 kHz to 16 kHz, respectively. In an alternative embodiment, the low-band portion and the high-band portion may occupy non-overlapping frequency bands of 50 Hz to 8 kHz and 8 kHz to 16 kHz, respectively. In another alternative embodiment, the low-band portion and the high-band portion may overlap (e.g., 50 Hz to 8 kHz and 7 kHz to 16 kHz, respectively).

In a particular embodiment, the input signal 130 may be a wideband (WB) signal having a frequency range of approximately 50 Hz to approximately 8 kHz. In this embodiment, the low-band portion of the input signal 130 may correspond to a frequency range of approximately 50 Hz to approximately 6.4 kHz, and the high-band portion of the input signal 130 may correspond to a frequency range of approximately 6.4 kHz to approximately 8 kHz.

In a particular embodiment, microphone 146 may capture input signal 130, and an analog-to-digital converter (ADC) at mobile device 104 may convert the captured input signal 130 from an analog waveform into a digital waveform consisting of digital audio samples. The digital audio samples may be processed by a digital signal processor. A gain adjuster may adjust the gain (e.g., the gain of the analog waveform or digital waveform) by increasing or decreasing the amplitude level of the audio signal (e.g., the analog waveform or digital waveform). The gain adjuster may operate in either the analog or digital domain. For example, the gain adjuster may operate in the digital domain and may adjust the digital audio samples generated by the analog-to-digital converter. After gain adjustment, an echo canceller may reduce any echo that may have been generated by the output of the speaker input to microphone 146. The digital audio samples may be "compressed" by a vocoder (speech encoder-decoder). The output of the echo canceller may be coupled to a vocoder pre-processing block, such as a filter, a noise processor, a rate converter, etc. The vocoder's encoder may compress the digital audio samples and form a transmit packet (a compressed bit representation of the digital audio samples). In a particular embodiment, the encoder of the vocoder can include an excitation signal generation module 122. The excitation signal generation module 122 can generate a high-band excitation signal 186, as described with reference to the first device 102. The excitation signal generation module 122 can provide the high-band excitation signal 186 to the high-band encoder 172.

High frequency band encoder 172 can be based on the high frequency band signal of high frequency band excitation signal 186 encoding input signal 130.For example, high frequency band encoder 172 can generate high frequency band bit stream 190 based on high frequency band excitation signal 186.High frequency band bit stream 190 can comprise high frequency band parameter information.For example, high frequency band bit stream 190 can comprise at least one of following: high frequency band linear predictive coding (LPC) coefficient, high frequency band line spectrum frequency (LSF), high frequency band line spectrum pair (LSP), gain shape (for example, corresponding to the time gain parameter of the subframe of particular frame), gain frame (for example, corresponding to the gain parameter of the energy ratio of the high frequency band and low frequency band for particular frame) or corresponding to other parameters of the high frequency band part of input signal 130.In a particular embodiment, high frequency band encoder 172 can use at least one in vector quantizer, hidden Markov model (HMM) or Gaussian mixture model (GMM) to determine the high frequency band LPC coefficient.High frequency band encoder 172 can determine high frequency band LSF, high frequency band LSP or the two based on LPC coefficient.

High frequency band encoder 172 can generate high frequency band parameter information based on the high frequency band signal of input signal 130.For example, the decoder of mobile device 104 can simulate the decoder of first device 102.The decoder of mobile device 104 can generate synthesized audio signal based on high frequency band excitation signal 186, as described with reference to first device 102.High frequency band encoder 172 can generate gain value (for example, gain shape, gain frame or described both) based on the comparison of synthesized audio signal and input signal 130.For example, gain value can correspond to the difference between synthesized audio signal and the input signal 130.High frequency band encoder 172 can provide high frequency band bit stream 190 to MUX 174.

MUX 174 can combine high-band bit stream 190 with low-band bit stream to generate bit stream 132. The low-band encoder of mobile device 104 can generate low-band bit stream based on the low-band signal of input signal 130. The low-band bit stream can include low-band parameter information (e.g., low-band LPC coefficients, low-band LSF, or both) and low-band excitation signal (e.g., low-band residual of input signal 130). Transmit packet can correspond to bit stream 132.

The transmit packets can be stored in a memory that can be shared with a processor of the mobile device 104. The processor can be a control processor in communication with a digital signal processor. The mobile device 104 can transmit the bitstream 132 to the first device 102 via the network 120. For example, the transmitter 176 can modulate some form of transmit packet (to which other information can be attached) and send the modulated information over the air via an antenna.

The excitation signal generation module 122 of the first device 102 can receive a bitstream 132. For example, an antenna of the first device 102 can receive some form of incoming packet including a transmit packet. The bitstream 132 can correspond to frames of an audio signal encoded using pulse code modulation (PCM). For example, an analog-to-digital converter (ADC) at the first device 102 can convert the bitstream 132 from an analog signal into a digital PCM signal having multiple frames.

The transmit packet may be "uncompressed by the decoder of the vocoder at the first device 102". The uncompressed waveform (or digital PCM signal) may be referred to as a reconstructed audio sample. The reconstructed audio sample may be post-processed by the vocoder post-processing block and may be used by the echo canceller to remove the echo. For clarity, the decoder of the vocoder and the vocoder post-processing block may be referred to as a vocoder decoder module. In some configurations, the output of the echo canceller may be processed by the excitation signal generation module 122. Alternatively, in other configurations, the output of the vocoder decoder module may be processed by the excitation signal generation module 122.

The excitation signal generation module 122 can extract low-band parameter information, low-band excitation signal and high-band parameter information from the bitstream 132. The voiced sound classifier 160 can determine a voiced sound classification 180 (e.g., a value of 0.0 to 1.0) indicating the voiced sound/unvoiced sound property (e.g., strongly voiced sound, weakly voiced sound, weakly unvoiced sound or strongly unvoiced sound) of the input signal 130, as described with reference to FIG2 . The voiced sound classifier 160 can provide the voiced sound classification 180 to the envelope adjuster 162.

Envelope adjuster 162 can determine the envelope of the representation of input signal 130.Envelope can be a time-varying envelope.For example, envelope can be updated more than once at the frame of every input signal 130.As another example, envelope can be updated in response to the envelope adjuster 162 of each sample that receives input signal 130.Compared when the voiced sound classification corresponds to strong voiceless, the variation degree of the shape of envelope can be larger when the voiced sound classification 180 corresponds to strong voiced.The representation of input signal 130 can comprise input signal 130 (or input signal 130 through coded version) low-band excitation signal, input signal 130 (or input signal 130 through coded version) high-band excitation signal or the harmonic expansion excitation signal.For example, excitation signal generation module 122 can generate the harmonic expansion excitation signal by extending input signal 130 (or input signal 130 through coded version) low-band excitation signal.

The envelope adjuster 162 may control the amount of the envelope based on the voiced speech classification 180, as described with reference to Figures 4 to 7. The envelope adjuster 162 may control the amount of the envelope by controlling characteristics of the envelope (e.g., shape, magnitude, gain, and/or frequency range). For example, the envelope adjuster 162 may control the frequency range of the envelope based on the cutoff frequency of the filter, as described with reference to Figure 4. The cutoff frequency may be determined based on the voiced speech classification 180.

As another example, the envelope adjuster 162 may control the shape of the envelope, the magnitude of the envelope, the gain of the envelope, or a combination thereof by adjusting one or more poles of high-band linear predictive coding (LPC) coefficients based on the voiced speech classification 180, as described with reference to FIG5. As another example, the envelope adjuster 162 may control the shape of the envelope, the magnitude of the envelope, the gain of the envelope, or a combination thereof by adjusting coefficients of a filter based on the voiced speech classification 180, as described with reference to FIG6. The characteristics of the envelope may be controlled in a transform domain (e.g., a frequency domain) or a time domain, as described with reference to FIG4-6.

Envelope adjuster 162 may provide a signal envelope 182 to modulator 164. Signal envelope 182 may correspond to a controlled amount of the envelope of the representation of input signal 130.

Modulator 164 may modulate white noise 156 using signal envelope 182 to generate modulated white noise 184 . Modulator 164 may provide modulated white noise 184 to output circuit 166 .

Output circuit 166 can generate high-band excitation signal 186 based on modulated white noise 184.For example, output circuit 166 can combine modulated white noise 184 and another signal to generate high-band excitation signal 186.In a specific embodiment, another signal can correspond to the extended signal generated based on the low-band excitation signal.For example, output circuit 166 can be by up-sampling low-band excitation signal, to applying absolute value function, down-sampling application absolute value function result and use adaptive whitening to come with linear prediction filter (for example, fourth-order linear prediction filter) with spectrum mode flattening through down-sampled signal to generate extended signal.In a specific embodiment, output circuit 166 can be based on harmonic parameter scaling modulated white noise 184 and another signal, as described with reference to Figures 4 to 7.

In a particular embodiment, output circuit 166 can combine the first ratio of modulated white noise and the second ratio of unmodulated white noise to generate the white noise through scaling, wherein the first ratio and the second ratio are determined based on voiced sound classification 180, as described with reference to Figure 7. In this embodiment, output circuit 166 can combine the white noise through scaling and another signal to generate high-frequency band excitation signal 186.Output circuit 166 can provide high-frequency band excitation signal 186 to high-frequency band synthesizer 168.

High-frequency band synthesizer 168 can generate synthetic high-frequency band signal 188 based on high-frequency band excitation signal 186.For example, high-frequency band synthesizer 168 can be based on specific high-frequency band model modeling and/or decoding high-frequency band parameter information, and can use high-frequency band excitation signal 186 to generate synthetic high-frequency band signal 188.High-frequency band synthesizer 168 can provide synthetic high-frequency band signal 188 to MUX 170.

The low-band decoder of first device 102 can generate synthetic low-band signal.For example, low-band decoder can be based on specific low-band model decoding and/or modeling low-band parameter information, and can use low-band excitation signal to generate synthetic low-band signal.MUX 170 can combine synthetic high-band signal 188 and synthetic low-band signal to generate output signal 116 (for example, through de-audio signal).

The output signal 116 can be amplified or suppressed by the gain adjuster. The first device 102 can provide the output signal 116 to the second user 154 via the speaker 142. For example, the output of the gain adjuster can be converted from a digital signal to an analog signal by a digital-to-analog converter and output via the speaker 142.

Thus, system 100 can enable generation of a "smooth" voicing synthesized signal when the synthesized audio signal corresponds to an unvoiced (or strongly unvoiced) input signal. A synthesized high-band signal can be generated using a noise signal modulated based on the voiced sound classification of the input signal. Compared to when the input signal is strongly unvoiced, the modulated noise signal can more closely correspond to the input signal when the input signal is strongly voiced. In a particular embodiment, when the input signal is strongly unvoiced, the synthesized high-band signal can have reduced sparsity or no sparsity, thereby producing a smoother (e.g., with fewer artifacts) synthesized audio signal.

With reference to figure 2, disclose the particular embodiment of the decoder that can operate to carry out high frequency band excitation signal generation, and it is designated as 200 usually.In a particular embodiment, decoder 200 can correspond to or be included in the system 100 of Fig. 1.For example, decoder 200 can be included in first device 102, mobile device 104 or described in the two.Decoder 200 can illustrate the decoding of the encoded audio signal at receiving device (for example, first device 102) place.

Decoder 200 comprises demultiplexer (DEMUX) 202, voiced sound factor producer 208 and high frequency band synthesizer 168 that are coupled to low frequency band synthesizer 204.Low frequency band synthesizer 204 and voiced sound factor producer 208 can be coupled to high frequency band synthesizer 168 via excitation signal generator 222.In a particular embodiment, voiced sound factor producer 208 can correspond to the voiced sound classifier 160 of Fig. 1. Excitation signal generator 222 can be the particular embodiment of the excitation signal generation module 122 of Fig. 1.For example, excitation signal generator 222 can comprise envelope adjuster 162, modulator 164, output circuit 166, voiced sound classifier 160 or its combination.Low frequency band synthesizer 204 and high frequency band synthesizer 168 can be coupled to MUX 170.

During operation, the DEMUX 202 can receive a bitstream 132. The bitstream 132 can correspond to frames of an audio signal encoded using pulse code modulation (PCM). For example, an analog-to-digital converter (ADC) at the first device 102 can convert the bitstream 132 from an analog signal into a digital PCM signal having a plurality of frames. The DEMUX 202 can generate a low-band portion 232 of the bitstream and a high-band portion 218 of the bitstream from the bitstream 132. The DEMUX 202 can provide the low-band portion 232 of the bitstream to the low-band synthesizer 204 and can provide the high-band portion 218 of the bitstream to the high-band synthesizer 168.

The low-band synthesizer 204 can extract and/or decode one or more parameters 242 (e.g., low-band parameter information of the input signal 130) and a low-band excitation signal 244 (e.g., low-band residual of the input signal 130) from the low-band portion 232 of the bitstream. In a particular embodiment, the low-band synthesizer 204 can extract harmonic parameters 246 from the low-band portion 232 of the bitstream.

The harmonics parameter 246 may be embedded in the low-band portion 232 of the bitstream during encoding of the bitstream 232 and may correspond to a ratio of harmonics to noise energy in the high-band of the input signal 130. The low-band synthesizer 204 may determine the harmonics parameter 246 based on the pitch gain value. The low-band synthesizer 204 may determine the pitch gain value based on the parameter 242. In a particular embodiment, the low-band synthesizer 204 may extract the harmonics parameter 246 from the low-band portion 232 of the bitstream. For example, the mobile device 104 may include the harmonics parameter 246 in the bitstream 132, as described with reference to FIG3.

The low-band synthesizer 204 may generate a synthesized low-band signal 234 using a specific low-band model based on the parameters 242 and the low-band excitation signal 244. The low-band synthesizer 204 may provide the synthesized low-band signal 234 to the MUX 170.

The voicing factor generator 208 can receive parameter 242 from low-band synthesizer 204. The voicing factor generator 208 can generate voicing factor 236 (for example, 0.0 to 1.0 value) based on parameter 242, previous voicing decision, one or more other factors or its combination. The voicing factor 236 can indicate the voiced sound/unvoiced sound property (for example, strong voiced sound, weak voiced sound, weak unvoiced sound or strong unvoiced sound) of input signal 130. Parameter 242 can comprise the zero crossing rate of the low-band signal of input signal 130, the first reflection coefficient, the energy that the adaptive codebook in the low-band excitation contributes and the low-band excitation and the ratio of the energy that the adaptive codebook and fixed codebook contribute, the pitch gain of the low-band signal of input signal 130 or its combination. The voicing factor generator 208 can determine voicing factor 236 based on equation 1.

Voicing Factor = ∑a _i * _pi + c, (Equation 1)

where i∈{0,…,M−1}, where a _i and c are weights, _pi corresponds to a specific measured signal parameter, and M corresponds to the number of parameters used for voiced voice factor determination.

In an illustrative embodiment, the voicing factor (Voicing Factor) = -0.4231*ZCR+0.2712*FR+0.0458*ACB_to_excitation+0.1849*PG+0.0138*prev_voicing_decision+0.0611, wherein ZCR corresponds to the zero crossing rate, FR corresponds to the first reflection coefficient, ACB_to_excitation corresponds to the ratio of the energy contributed by the adaptive codebook in the low-band excitation to the energy of the sum of the contributions of the adaptive codebook and the fixed codebook in the low-band excitation, PG corresponds to the pitch gain, and previous_voicing_decision corresponds to another voicing factor previously calculated for another frame. In a particular embodiment, the voicing factor generator 208 can use a higher threshold value for classifying a frame as unvoiced rather than voiced. For example, if the aforementioned frame is classified as unvoiced and the frame has a voiced value that satisfies a first threshold value (e.g., a low threshold value), the voicing factor generator 208 can classify the frame as unvoiced. The voicing factor generator 208 can determine the voicing value based on the following: the zero crossing rate of the low-band signal of input signal 130, the first reflection coefficient, the ratio of the energy of the summation that adaptive codebook contributes in the low-band excitation and adaptive codebook and fixed codebook contribute in the low-band excitation, the pitch gain of the low-band signal of input signal 130 or its combination. Alternatively, if the voicing value of frame satisfies the second threshold value (for example, very low threshold value), then the voicing factor generator 208 can be classified as unvoiced by the frame. In a particular embodiment, the voicing factor 236 can correspond to the voicing classification 180 of Fig. 1.

Excitation signal generator 222 can receive low-band excitation signal 244 and harmonic parameter 246 from low-band synthesizer 204, and can receive voiced sound factor 236 from voiced sound factor producer 208. Excitation signal generator 222 can generate high-band excitation signal 186 based on low-band excitation signal 244, harmonic parameter 246 and voiced sound factor 236, as described with reference to Figure 1 and 4 to 7. For example, envelope adjuster 162 can be based on the amount of the envelope of voiced sound factor 236 control low-band excitation signal 244, as described with reference to Figure 1 and 4 to 7. In a particular embodiment, signal envelope 182 can correspond to the controlled amount of envelope. Envelope adjuster 162 can provide signal envelope 182 to modulator 164.

Modulator 164 may modulate white noise 156 using signal envelope 182 to generate modulated white noise 184 , as described with reference to FIGS. 1 and 4 through 7 . Modulator 164 may provide modulated white noise 184 to output circuit 166 .

The output circuit 166 can generate a high-frequency band excitation signal 186 by combining the modulated white noise 184 and another signal, as described with reference to Figures 1 and 4 to 7. In a particular embodiment, the output circuit 166 can combine the modulated white noise 184 and another signal based on the harmonicity parameter 246, as described with reference to Figures 4 to 7.

Output circuit 166 can be provided to high-frequency band synthesizer 168 with high-frequency band excitation signal 186.High-frequency band synthesizer 168 can be provided to MUX 170 with synthetic high-frequency band signal 188 based on the high-frequency band portion 218 of high-frequency band excitation signal 186 and bit stream.For example, high-frequency band synthesizer 168 can extract the high-frequency band parameters of input signal 130 from the high-frequency band portion 218 of bit stream.High-frequency band synthesizer 168 can use high-frequency band parameters and high-frequency band excitation signal 186 to generate synthetic high-frequency band signal 188 based on specific high-frequency band model.In a particular embodiment, MUX 170 can combine synthetic low-frequency band signal 234 and synthetic high-frequency band signal 188 to generate output signal 116.

Therefore, when the synthesized audio signal corresponds to an unvoiced (or strongly unvoiced) input signal, the decoder 200 of FIG. 2 can enable the generation of a "smooth" voicing synthesized signal. A noise signal modulated based on the voiced sound classification of the input signal can be used to generate a synthesized high-frequency band signal. Compared to when the input signal is a strongly unvoiced sound, the modulated noise signal can more closely correspond to the input signal when the input signal is a strongly voiced sound. In a particular embodiment, when the input signal is a strongly unvoiced sound, the synthesized high-frequency band signal can have a reduced sparsity or do not have sparsity, thereby producing a smoother (e.g., with fewer artifacts) synthesized audio signal. In addition, determining the voiced sound classification (or voiced sound factor) based on previous voiced sound decisions can alleviate the effect of the misclassification of frames and can produce a smoother transition between voiced audio frames and unvoiced audio frames.

With reference to figure 3, disclose the particular embodiment of the encoder that can operate to carry out high frequency band excitation signal generation, and it is designated as 300 usually.In a particular embodiment, encoder 300 can correspond to or be included in the system 100 of Fig. 1.For example, encoder 300 can be included in first device 102, mobile device 104 or described in the two.Encoder 300 can illustrate the coding of the audio signal at transmitting device (for example, mobile device 104) place.

The encoder 300 includes a filter bank 302 coupled to a low-band encoder 304, a voice factor generator 208, and a high-band encoder 172. The low-band encoder 304 may be coupled to a MUX 174. The low-band encoder 304 and the voice factor generator 208 may be coupled to the high-band encoder 172 via an excitation signal generator 222. The high-band encoder 172 may be coupled to a MUX 174.

During operation, bank of filters 302 can receive input signal 130. For example, input signal 130 can be received by the mobile device 104 of Fig. 1 via microphone 146. Bank of filters 302 can separate input signal 130 into a plurality of signals comprising low-band signal 334 and high-band signal 340. For example, bank of filters 302 can use the low-pass filter corresponding to the lower frequency sub-band (for example, 50Hz to 7kHz) of input signal 130 to generate low-band signal 334 and can use the high-pass filter corresponding to the higher frequency sub-band (for example, 7kHz to 16kHz) of input signal 130 to generate high-band signal 340. Bank of filters 302 can provide low-band signal 334 to low-band encoder 304 and can provide high-band signal 340 to high-band encoder 172.

Low band encoder 304 can for example generate parameters 242 based on low band signals 334 (low band parameter information) and low band excitation signal 244.For example, parameter 242 can comprise low band LPC coefficient, low band LSF, low band line spectrum to (LSP) or its combination.Low band excitation signal 244 can correspond to low band residual signal.Low band encoder 304 can for example generate parameters 242 and low band excitation signal 244 based on specific low band model (specific linear prediction model).For example, low band encoder 304 can for example generate parameters 242 of low band signals 334 (corresponding to the filter coefficient of formant), can carry out back filtering based on parameter 242 pairs of low band signals 334, and can generate low band excitation signal 244 (for example, the low band residual signal of low band signals 334) from the signal of described back filtering of low band signals 334. The low-band encoder 304 can generate a low-band bit stream 342 that includes parameters 242 and a low-band excitation signal 244. In a particular embodiment, the low-band bit stream 342 can include harmonicity parameters 246. For example, the low-band encoder 304 can determine the harmonicity parameters 246, as described with reference to the low-band synthesizer 204 of Figure 2.

The low-band encoder 304 can provide the parameters 242 to the voiced sound factor generator 208 and can provide the low-band excitation signal 244 and the harmonic parameters 246 to the excitation signal generator 222. The voiced sound factor generator 208 can determine the voiced sound factor 236 based on the parameters 242, as described with reference to Figure 2. The excitation signal generator 222 can determine the high-band excitation signal 186 based on the low-band excitation signal 244, the harmonic parameters 246 and the voiced sound factor 236, as described with reference to Figures 2 and 4 to 7.

Excitation signal generator 222 can provide high-frequency band excitation signal 186 to high-frequency band encoder 172.High-frequency band encoder 172 can generate high-frequency band bit stream 190 based on high-frequency band signal 340 and high-frequency band excitation signal 186, as described with reference to Figure 1.High-frequency band encoder 172 can provide high-frequency band bit stream 190 to MUX 174.MUX 174 can combine low-frequency band bit stream 342 and high-frequency band bit stream 190 to generate bit stream 132.

Therefore, the encoder 300 can make it possible to simulate a decoder at a receiving device that generates a synthetic audio signal using a noise signal modulated based on the voiced sound classification of the input signal. The encoder 300 can generate high-frequency band parameters (e.g., gain values) that are used to generate a synthetic audio signal that closely approximates the input signal 130.

Fig. 4 to 7 is the figure of the particular embodiment of the method that the high frequency band excitation signal generates for explanation.Can be by one or more components execution Figure 4 to 7 method for the system 100 to 300 of Fig. 1 to 3 each.For example, can be by one or more components of the high frequency band excitation signal generation module 122 of Fig. 1, the excitation signal producer 222 of Fig. 2 and/or Fig. 3, the voiced sound factor producer 208 of Fig. 2 or its combination execution Figure 4 to 7 method each.Fig. 4 to 7 explanation is generated in the transform domain, in the time domain or in the transform domain or the alternate embodiment of the method for the high frequency band excitation signal that represents in the time domain.

4, a diagram of a particular embodiment of a method of high-band excitation signal generation is shown and generally designated 400. Method 400 may correspond to generating a high-band excitation signal represented in a transform domain or a time domain.

Method 400 is included in and determines voiced sound factor at 404 places.For example, the voiced sound factor producer 208 of Fig. 2 can determine voiced sound factor 236 based on representative signal 422.In a particular embodiment, voiced sound factor producer 208 can determine voiced sound factor 236 based on one or more other signal parameters.In a particular embodiment, some signal parameters can be combined to work and determine voiced sound factor 236.For example, voiced sound factor producer 208 can determine voiced sound factor 236 based on low-band part 232 (or low-band signal 334 of Fig. 3), parameter 242, previous voiced sound decision, one or more other factors or its combination of bit stream, as described with reference to Figures 2 to 3. Representative signal 422 can comprise low-band part 232, low-band signal 334 of bit stream or the extended signal generated by extended low-band excitation signal 244.Representative signal 422 can be represented in transform (for example, frequency) domain or time domain. For example, the excitation signal generation module 122 can generate the representative signal 422 by applying a transform (e.g., a Fourier transform) to the input signal 130, the bit stream 132 of Figure 1, the low-band portion 232 of the bit stream, the low-band signal 334, an extended signal generated by extending the low-band excitation signal 244 of Figure 2, or a combination thereof.

Method 400 also includes calculating a low-pass filter (LPF) cutoff frequency at 408 and controlling the amount of signal envelope at 410. For example, envelope adjuster 162 of FIG. 1 may calculate LPF cutoff frequency 426 based on voice factor 236. If voice factor 236 indicates strongly voiced audio, LPF cutoff frequency 426 may be higher, indicating a higher influence of harmonic components of the temporal envelope. When voice factor 236 indicates strongly unvoiced audio, LPF cutoff frequency 426 may be lower, corresponding to a lower (or no) influence of harmonic components of the temporal envelope.

Envelope adjuster 162 can control the magnitude of signal envelope 182 by controlling characteristics (e.g., frequency range) of signal envelope 182. For example, envelope adjuster 162 can control the characteristics of signal envelope 182 by applying a lowpass filter 450 to representative signal 422. The cutoff frequency of lowpass filter 450 can be substantially equal to LPF cutoff frequency 426. Envelope adjuster 162 can control the frequency range of signal envelope 182 by tracking the temporal envelope of representative signal 422 based on LPF cutoff frequency 426. For example, lowpass filter 450 can filter representative signal 422 such that the filtered signal has a frequency range defined by LPF cutoff frequency 426. For illustration, the frequency range of the filtered signal can be below LPF cutoff frequency 426. In a particular embodiment, the filtered signal can have an amplitude that matches the amplitude of representative signal 422 below LPF cutoff frequency 426 and can have a low amplitude (e.g., substantially equal to zero) above LPF cutoff frequency 426.

Graph 470 illustrates an original spectral shape 482. Original spectral shape 482 may represent signal envelope 182 of representative signal 422. First spectral shape 484 may correspond to a filtered signal generated by applying a filter having LPF cutoff frequency 426 to representative signal 422.

The LPF cutoff frequency 426 may determine the tracking speed. For example, the time envelope may be tracked faster (e.g., updated more frequently) when the voiced factor 236 indicates voiced speech than when the voiced factor 236 indicates unvoiced speech. In certain embodiments, the envelope adjuster 162 may control the characteristics of the signal envelope 182 in the time domain. For example, the envelope adjuster 162 may control the characteristics of the signal envelope 182 on a sample-by-sample basis. In alternative embodiments, the envelope adjuster 162 may control the characteristics of the signal envelope 182 represented in the transform domain. For example, the envelope adjuster 162 may control the characteristics of the signal envelope 182 by tracking the spectral shape based on the tracking speed. The envelope adjuster 162 may provide the signal envelope 182 to the modulator 164 of FIG. 1 .

Method 400 further includes multiplying signal envelope 182 with white noise 156 at 412. For example, modulator 164 of FIG1 may modulate white noise 156 using signal envelope 182 to generate modulated white noise 184. Signal envelope 182 may modulate white noise 156 represented in a transform domain or a time domain.

Method 400 also includes determining mixing at 406. For example, the modulator 164 of FIG. 1 may determine a first gain (e.g., noise gain 434) to be applied to the modulated white noise 184 and a second gain (e.g., harmonic gain 436) to be applied to the representative signal 422 based on the harmonicity parameter 246 and the voicing factor 236. For example, the noise gain 434 (e.g., between 0 and 1) and the harmonic gain 436 may be calculated to match the ratio of harmonic to noise energy indicated by the harmonicity parameter 246. The modulator 164 may increase the noise gain 434 when the voicing factor 236 indicates strong unvoiced speech and may decrease the noise gain 434 when the voicing factor 236 indicates strong voiced speech. In a particular embodiment, the modulator 164 may determine the harmonic gain 436 based on the noise gain 434. In a particular embodiment, the harmonic gain

The method 400 further includes multiplying the modulated white noise 184 and the noise gain 434 at 414. For example, the output circuit 166 of FIG.

The method 400 also includes multiplying the representative signal 422 and the harmonic gain 436 at 416. For example, the output circuit 166 of FIG.

Method 400 is further included in 418 places and will be added through the modulated white noise 438 of scaling and the representative signal 440 of scaling.For example, the output circuit 166 of Fig. 1 can be by will be generated high frequency band excitation signal 186 through the modulated white noise 438 of scaling and the representative signal 440 of scaling (for example, adding).In an alternate embodiment, can be by the modulator 164 execution operation 414, operation 416 or described both of Fig. 1.High frequency band excitation signal 186 can be in transform domain or time domain.

In certain embodiments, the method 400 can be used to determine the ratio of modulated white noise 184 and representative signal 422 by gain factor (for example, noise gain 434 and harmonic gain 436) based on harmonic parameter 246. Scalable modulated white noise 184 and representative signal 422 make the harmonic waves of the high-frequency band excitation signal 186 and the ratio of the harmonic waves of the high-frequency band signal of the approximate input signal 130 of the noise energy and the noise energy.

In certain embodiments, the method 400 of FIG4 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), via firmware devices, or any combination thereof. As an example, the method 400 of FIG4 may be performed by a processor executing instructions (as described with respect to FIG9 ).

With reference to figure 5, show the figure of the particular embodiment of the method that high-frequency band excitation signal generates, and it is designated as 500 usually.Method 500 can comprise the amount of the signal envelope that represents in transform domain by control, modulation white noise that represents in transform domain or described two generate high-frequency band excitation signal.

Method 500 includes operations 404, 406, 412, and 414 of method 400. Representative signal 422 may be represented in a transform (eg, frequency) domain, as described with reference to FIG.

The method 500 also includes calculating a bandwidth expansion factor at 508. For example, the envelope adjuster 162 of FIG1 can determine the bandwidth expansion factor 526 based on the voiced speech factor 236. For example, the bandwidth expansion factor 526 can indicate a greater bandwidth expansion when the voiced speech factor 236 indicates strong voiced speech than when the voiced speech factor 236 indicates strong unvoiced speech.

Method 500 further includes, at 510, generating a spectrum by adjusting high-band LPC poles. For example, envelope adjuster 162 may determine LPC poles associated with representative signal 422. Envelope adjuster 162 may control characteristics of signal envelope 182 by controlling the magnitude of signal envelope 182, the shape of signal envelope 182, the gain of signal envelope 182, or a combination thereof. For example, envelope adjuster 162 may control the magnitude of signal envelope 182, the shape of signal envelope 182, the gain of signal envelope 182, or a combination thereof by adjusting the LPC poles based on bandwidth expansion factor 526. In a particular embodiment, the LPC poles may be adjusted in the transform domain. Envelope adjuster 162 may generate a spectrum based on the adjusted LPC poles.

Graph 570 illustrates an original spectral shape 582. Original spectral shape 582 may represent signal envelope 182 of representative signal 422. Original spectral shape 582 may be generated based on LPC poles associated with representative signal 422. Envelope adjuster 162 may adjust the LPC poles based on voiced speech factor 236. Envelope adjuster 162 may apply a filter corresponding to the adjusted LPC poles to representative signal 422 to generate a filtered signal having a first spectral shape 584 or a second spectral shape 586. When voiced speech factor 236 indicates strong voiced speech, first spectral shape 584 of the filtered signal may correspond to the adjusted LPC poles. When voiced speech factor 236 indicates strong unvoiced speech, second spectral shape 586 of the filtered signal may correspond to the adjusted LPC poles.

The signal envelope 182 may correspond to the generated spectrum, the adjusted LPC poles, the LPC coefficients associated with the representative signal 422 having the adjusted LPC poles, or a combination thereof. The envelope adjuster 162 may provide the signal envelope 182 to the modulator 164 of FIG.

The modulator 164 may modulate the white noise 156 using the signal envelope 182 to generate modulated white noise 184, as described with reference to operation 412 of the method 400. The modulator 164 may modulate the white noise 156 represented in the transform domain. The output circuit 166 of FIG. 1 may generate scaled modulated white noise 438 based on the modulated white noise 184 and the noise gain 434, as described with reference to operation 414 of the method 400.

Method 500 is also included in 512 places and high-frequency band LPC spectrum 542 and representative signal 422 are multiplied one another.For example, the output circuit 166 of Fig. 1 can use high-frequency band LPC spectrum 542 to filter representative signal 422 and generate filtered signal 544.In a particular embodiment, output circuit 166 can determine high-frequency band LPC spectrum 542 based on the high-frequency band parameter (for example, high-frequency band LPC coefficient) associated with representative signal 422.For illustration, output circuit 166 can determine high-frequency band LPC spectrum 542 based on the high-frequency band part 218 of the bit stream of Fig. 2 or based on the high-frequency band parameter information generated from the high-frequency band signal 340 of Fig. 3.

Representative signal 422 can correspond to the extended signal that generates from the low-frequency band excitation signal 244 of Fig. 2. Output circuit 166 can use high-frequency band LPC spectrum 542 synthetic extended signals to generate through filtered signal 544.Synthesis can be carried out in transform domain.For example, output circuit 166 can use the multiplication in frequency domain to perform synthesis.

The method 500 further includes multiplying the filtered signal 544 and the harmonic gain 436 at 516. For example, the output circuit 166 of FIG1 may multiply the filtered signal 544 and the harmonic gain 436 to generate the scaled filtered signal 540. In a particular embodiment, operation 512, operation 516, or both may be performed by the modulator 164 of FIG1.

Method 500 also is included in 518 places and will be added through the modulated white noise 438 of scaling and the filtered signal 540 through scaling.For example, the output circuit 166 of Fig. 1 can combine through the modulated white noise 438 of scaling and the filtered signal 540 through scaling to generate high-frequency band excitation signal 186.Can represent high-frequency band excitation signal 186 in transform domain.

In a specific embodiment, can dynamically determine the ratio of modulated white noise 184 and filtered signal 544 by gain (for example, noise gain 434 and harmonic gain 436) based on harmonic parameter 246. Scalable modulated white noise 184 and filtered signal 544 make the harmonic waves of the high band signal of the approximate input signal 130 of the ratio of the harmonic waves and the noise energy of high band excitation signal 186 and the noise energy.

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), via firmware devices, 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 FIG9).

6, a diagram of a particular embodiment of a method of high-band excitation signal generation is shown and generally designated 600. Method 600 may include generating a high-band excitation signal by controlling the amount of a signal envelope in the time domain.

Method 600 includes operations 404, 406, and 414 of method 400 and operation 508 of method 500. Representative signal 422 and white noise 156 may be in the time domain.

Method 600 also includes performing LPC synthesis at 610. For example, envelope adjuster 162 of FIG. 1 can control characteristics (e.g., shape, magnitude, and/or gain) of signal envelope 182 by adjusting filter coefficients based on bandwidth expansion factor 526. In certain embodiments, LPC synthesis can be performed in the time domain. The filter coefficients can correspond to high-band LPC coefficients. The LPC filter coefficients can represent spectral peaks. Controlling spectral peaks by adjusting the LPC filter coefficients can enable control of the degree of modulation of white noise 156 based on voicedness factor 236.

For example, when the voiced factor 236 indicates voiced speech, the spectral peaks may be preserved. As another example, when the voiced factor 236 indicates unvoiced speech, the spectral peaks may be smoothed while preserving the overall spectral shape.

Graph 670 illustrates an original spectral shape 682. Original spectral shape 682 may represent signal envelope 182 of representative signal 422. Original spectral shape 682 may be generated based on LPC filter coefficients associated with representative signal 422. Envelope adjuster 162 may adjust the LPC filter coefficients based on voice factor 236. Envelope adjuster 162 may apply a filter corresponding to the adjusted LPC filter coefficients to representative signal 422 to generate a filtered signal having a first spectral shape 684 or a second spectral shape 686. When voice factor 236 indicates strong voiced speech, first spectral shape 684 of the filtered signal may correspond to the adjusted LPC filter coefficients. When voice factor 236 indicates strong voiced speech, spectral peaks may be preserved, as illustrated by first spectral shape 684. When voice factor 236 indicates strong unvoiced speech, second spectral shape 686 may correspond to the adjusted LPC filter coefficients. When the voiced factor 236 indicates strong unvoiced speech, the overall spectral shape can be maintained while the spectral peaks can be smoothed, as illustrated by the second spectral shape 686. The signal envelope 182 can correspond to the adjusted filter coefficients. The envelope adjuster 162 can provide the signal envelope 182 to the modulator 164 of FIG. 1.

The modulator 164 may modulate the white noise 156 using the signal envelope 182 (e.g., the adjusted filter coefficients) to generate a modulated white noise 184. For example, the modulator 164 may apply a filter to the white noise 156 to generate the modulated white noise 184, wherein the filter has the adjusted filter coefficients. The modulator 164 may provide the modulated white noise 184 to the output circuit 166 of FIG. 1 . The output circuit 166 may multiply the modulated white noise 184 by the noise gain 434 to generate a scaled modulated white noise 438, as described with reference to operation 414 of FIG.

Method 600 is further included in 612 places and carries out high frequency band LPC and synthesizes.For example, the output circuit 166 of Fig. 1 can synthesize representative signal 422 and generate synthetic high frequency band signal 614.Can carry out synthesis in time domain.In a particular embodiment, can generate representative signal 422 by expanding low frequency band excitation signal.Output circuit 166 can be by the composite filter that will use high frequency band LPC to be applied to representative signal 422 and generate synthetic high frequency band signal 614.

Method 600 also is included in 616 places and synthetic high frequency band signal 614 and harmonic gain 436 are multiplied one another.For example, the output circuit 166 of Fig. 1 can apply harmonic gain 436 to synthetic high frequency band signal 614 to generate the synthetic high frequency band signal 640 through scaling.In an alternative embodiment, the modulator 164 of Fig. 1 can perform operation 612, operation 616 or described both.

Method 600 further includes adding the modulated white noise 438 and the synthetic high-band signal 640 through scaling at 618 places. For example, the output circuit 166 of Fig. 1 can combine the modulated white noise 438 and the synthetic high-band signal 640 through scaling to generate the high-band excitation signal 186 through scaling.

In one embodiment, the method 600 can be used to determine the ratio of modulated white noise 184 and synthetic high-frequency band signals 614 based on the voicing factor 236. The ... so that the harmonic waves of the high-frequency band excitation signal 186 and the ratio of the noise energy are similar to the ratio of the harmonic waves of the high-frequency band signals of the input signal 130.

In certain embodiments, the method 600 of FIG6 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), via firmware devices, or any combination thereof. As an example, the method 600 of FIG6 may be performed by a processor executing instructions (as described with respect to FIG9 ).

With reference to Figure 7, show the figure of the particular embodiment of the method that high-frequency band excitation signal generates, and it is usually designated as 700.Method 700 can correspond to generating the high-frequency band excitation signal by the amount of the signal envelope that represents in time domain or transform (for example, frequency) domain by control.

Method 700 includes operations 404, 406, 412, 414, and 416 of method 400. Representative signal 422 may be represented in a transform domain or a time domain. Method 700 also includes determining a signal envelope at 710. For example, envelope adjuster 162 of FIG. 1 may generate signal envelope 182 by applying a low-pass filter having constant coefficients to representative signal 422.

The method 700 also includes determining an rms value at 702. For example, the modulator 164 of FIG.

The method 700 further includes multiplying the RMS value by the white noise 156 at 712. For example, the output circuit 166 of FIG.

1 may multiply the signal envelope 182 by the white noise 156 to generate the modulated white noise 184, as described with reference to operation 412 of the method 400. The white noise 156 may be represented in a transform domain or a time domain.

Method 700 also includes determining a gain ratio of modulated and unmodulated white noise at 704. For example, output circuit 166 of FIG. 1 may determine an unmodulated noise gain 734 and a modulated noise gain 732 based on noise gain 434 and voice factor 236. If voice factor 236 indicates that the encoded audio signal corresponds to strongly voiced audio, modulated noise gain 732 may correspond to a higher ratio of noise gain 434. If voice factor 236 indicates that the encoded audio signal corresponds to strongly unvoiced audio, unmodulated noise gain 734 may correspond to a higher ratio of noise gain 434.

The method 700 further includes multiplying the unmodulated noise gain 734 and the unmodulated white noise 736 at 714. For example, the output circuit 166 of FIG.

Output circuit 166 may apply modulated noise gain 732 to modulated white noise 184 to generate scaled modulated white noise 740 , as described with reference to operation 414 of method 400 .

Method 700 also includes adding scaled unmodulated white noise 742 to scaled white noise 744 at 716. For example, output circuit 166 of FIG.

Method 700 is further included in 718 places and will add the white noise 744 through scaling and the representative signal 440 through scaling.For example, output circuit 166 can combine the white noise 744 through scaling and generate high-frequency band excitation signal 186 through the representative signal 440 through scaling.Method 700 can use the representative signal 422 and the white noise 156 that represent in transform (or time) domain to generate the high-frequency band excitation signal 186 that represents in transform (or time) domain.

Therefore, method 700 can make the ratio of unmodulated white noise 736 and modulated white noise 184 can be determined dynamically based on voicing factor 236 by gain factor (for example, unmodulated noise gain 734 and modulated noise gain 732).Compared to the high-frequency band signal corresponding to the white noise modulated by the low-band residual through sparse coding, the high-frequency band excitation signal 186 for strong unvoiced audio can correspond to the unmodulated white noise with less artifacts.

In certain embodiments, the method 700 of FIG. 7 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), via firmware devices, or any combination thereof. As an example, the method 700 of FIG. 7 may be performed by a processor executing instructions (as described with respect to FIG. 9 ).

With reference to figure 8, show the process flow diagram of the particular embodiment of the method that high frequency band excitation signal generates, and it is designated as 800 usually.Can be by one or more component execution method 800 of the system 100 to 300 of Fig. 1 to 3.For example, can be by the voiced sound factor producer 208 of one or more components of the high frequency band excitation signal generation module 122 of Fig. 1, Fig. 2 or Fig. 3, Fig. 2 or its combination execution method 800.

Method 800 includes determining, at a device, a voiced speech classification of an input signal at 802. The input signal may correspond to an audio signal. For example, the voiced speech classifier 160 of FIG. 1 may determine the voiced speech classification 180 of the input signal 130, as described with reference to FIG. 1. The input signal 130 may correspond to an audio signal.

Method 800 is also included in 804 places based on the amount of the envelope of the representation of the voiced sound classification control input signal.For example, the envelope adjuster 162 of Fig. 1 can be based on the amount of the envelope of the representation of voiced sound classification 180 control input signal 130, as described with reference to Figure 1.The representation of input signal 130 can be the low frequency band part of bit stream (for example, the bit stream 232 of Fig. 2), low frequency band signal (for example, the low frequency band signal 334 of Fig. 3), extended signal, another signal or its combination generated by extending low frequency band excitation signal (for example, the low frequency band excitation signal 244 of Fig. 2).For example, the representation of input signal 130 can comprise the representative signal 422 of Fig. 4 to 7.

Method 800 further includes, at 806, modulating the white noise signal based on the controlled amount of the envelope. For example, modulator 164 of FIG. 1 may modulate white noise 156 based on signal envelope 182. Signal envelope 182 may correspond to the controlled amount of the envelope. For illustration, modulator 164 may modulate white noise 156 in the time domain, such as in FIG. 4 and 6-7. Alternatively, modulator 164 may modulate white noise 156 represented in a transform domain, such as in FIG. 4-7.

The method 800 also includes generating a high-band excitation signal based on the modulated white noise signal at 808. For example, the output circuit 166 of FIG. 1 may generate the high-band excitation signal 186 based on the modulated white noise 184, as described with reference to FIG.

Thus, the method 800 of FIG. 8 may enable generation of a high-band excitation signal based on a controlled amount of an envelope of an input signal, wherein the amount of the envelope is controlled based on a voiced speech classification.

In certain embodiments, the method 800 of FIG8 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), via firmware devices, or any combination thereof. As an example, the method 800 of FIG8 may be performed by a processor executing instructions (as described with respect to FIG9 ).

Although the embodiment description of Fig. 1 to 8 generates high-band excitation signal based on low-frequency band signal, in other embodiments, input signal 130 can be filtered to produce a plurality of frequency band signals.For example, a plurality of frequency band signals can comprise lower-frequency band signal, medium-band signal, higher-frequency band signal, one or more extra frequency band signals, or its combination.The medium-frequency band signal can correspond to the frequency range higher than the low-frequency band signal, and the higher-frequency band signal can correspond to the frequency range higher than the medium-frequency band signal. Lower-frequency band signal and medium-band signal can correspond to overlapping or non-overlapping frequency range.Medium-band signal and higher-frequency band signal can correspond to overlapping or non-overlapping frequency range.

The excitation signal generation module 122 can use a first frequency band signal (e.g., a lower frequency band signal or a middle frequency band signal) to generate an excitation signal corresponding to a second frequency band signal (e.g., a middle frequency band signal or an upper frequency band signal), wherein the first frequency band signal corresponds to a lower frequency range than the second frequency band signal.

In a particular embodiment, the excitation signal generation module 122 may use the first frequency band signal to generate a plurality of excitation signals corresponding to the plurality of frequency band signals. For example, the excitation signal generation module 122 may use the lower frequency band signal to generate a mid-band excitation signal corresponding to the mid-band signal, a higher frequency band excitation signal corresponding to the higher frequency band signal, one or more additional frequency band excitation signals, or a combination thereof.

9 , a block diagram of a particular illustrative embodiment of a device (e.g., a wireless communication device) is depicted and generally designated 900. In various embodiments, device 900 may have fewer or more components than illustrated in FIG 9 . In an illustrative embodiment, device 900 may correspond to mobile device 104 or first device 102 of FIG 1 . In an illustrative embodiment, device 900 may operate according to one or more of methods 400-800 of FIGs. 4-8 .

In a particular embodiment, device 900 includes processor 906 (for example, central processing unit (CPU)). Device 900 may include one or more additional processors 910 (for example, one or more digital signal processors (DSP)). Processor 910 may include speech and music decoding decoder (codec) 908 and echo canceller 912. Speech and music codec 908 may include the voiced sound factor producer 208, vocoder encoder 936, vocoder decoder 938 of the excitation signal generation module 122, excitation signal generator 222, Fig. 2, or vocoder encoder 936 and vocoder decoder 938. In a particular embodiment, vocoder encoder 936 may include the high frequency band encoder 172 of Fig. 1, the low frequency band encoder 304 of Fig. 3 or both. In a particular embodiment, vocoder decoder 938 may include the low frequency band synthesizer 204 of high frequency band synthesizer 168, Fig. 2 or both.

As illustrated, the excitation signal generation module 122, the voiced speech factor generator 208, and the excitation signal generator 222 may be shared components accessible by the vocoder encoder 936 and the vocoder decoder 938. In other embodiments, one or more of the excitation signal generation module 122, the voiced speech factor generator 208, and/or the excitation signal generator 222 may be included in the vocoder encoder 936 and the vocoder decoder 938.

Although the speech and music codec 908 is illustrated as a component of the processor 910 (e.g., dedicated circuitry and/or executable programming code), in other embodiments, one or more components of the speech and music codec 908 (e.g., the excitation signal generation module 122) may be included in the processor 906, the codec 934, another processing component, or a combination thereof.

Device 900 may include memory 932 and codec 934. Device 900 may include a wireless controller 940 coupled to an antenna 942 via a transceiver 950. Device 900 may include a display 928 coupled to a display controller 926. A speaker 948, a microphone 946, or both may be coupled to codec 934. In a particular embodiment, speaker 948 may correspond to speaker 142 of FIG. 1. In a particular embodiment, microphone 946 may correspond to microphone 146 of FIG. 1. Codec 934 may include a digital-to-analog converter (DAC) 902 and an analog-to-digital converter (ADC) 904.

In a particular embodiment, the codec 934 may receive an analog signal from the microphone 946, convert the analog signal into a digital signal using the analog-to-digital converter 904, and provide the digital signal to the voice and music codec 908 (e.g., in pulse code modulation (PCM) format). The voice and music codec 908 may process the digital signal. In a particular embodiment, the voice and music codec 908 may provide the digital signal to the codec 934. The codec 934 may convert the digital signal into an analog signal using the digital-to-analog converter 902 and may provide the analog signal to the speaker 948.

Memory 932 may include instructions 956 that may be executed by processor 906, processor 910, codec 934, another processing unit, or a combination thereof of device 900 to perform the methods and processes disclosed herein (e.g., one or more of methods 400-800 of Figures 4-8).

One or more components of systems 100-300 may be implemented via dedicated hardware (e.g., circuitry) or a processor that executes instructions to perform one or more tasks, or a combination thereof. For example, memory 932 or one or more components of processor 906, processor 910, and/or codec 934 may be memory devices 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), registers, a hard disk, a removable disk, or a compact disk read-only memory (CD-ROM). The memory device may include instructions (e.g., instructions 956) that, when executed by a computer (e.g., a processor in codec 934, processor 906, and/or processor 910), cause the computer to perform at least a portion of one or more of methods 400-800 of Figures 4-8. As an example, memory 932 or one or more components of processor 906, processor 910, codec 934 may be non-transitory computer-readable media that includes instructions (e.g., instructions 956) that, when executed by a computer (e.g., a processor in codec 934, processor 906, and/or processor 910), cause the computer to perform at least a portion of one or more of methods 400 to 800 of Figures 4 to 8.

In a particular embodiment, device 900 may be included in a system-in-package or system-on-a-chip device (e.g., a mobile station modem (MSM)) 922. In a particular embodiment, processor 906, processor 910, display controller 926, memory 932, codec 934, wireless controller 940, and transceiver 950 are included in the system-in-package or system-on-a-chip device 922. In a particular embodiment, input device 930 (e.g., a touch screen and/or keypad) and power supply 944 are coupled to the system-on-a-chip device 922. Furthermore, in a particular embodiment, as illustrated in FIG9 , display 928, input device 930, speaker 948, microphone 946, antenna 942, and power supply 944 are external to the system-on-a-chip device 922. However, each of the display 928, input device 930, speaker 948, microphone 946, antenna 942, and power supply 944 may be coupled to a component of the system-on-a-chip device 922, such as an interface or controller.

Device 900 may include a mobile communication device, a smart phone, a cellular phone, a laptop computer, a computer, a tablet computer, a personal digital assistant, a display device, a television, a game console, a music player, a radio, a digital video player, a digital video disc (DVD) player, a tuner, a camera, a navigation device, a decoder system, an encoder system, or any combination thereof.

In an illustrative embodiment, the processor 910 may be operable to perform all or part of the methods or operations described with reference to Figures 1 to 8. For example, the microphone 946 may capture an audio signal (e.g., the input signal 130 of Figure 1). The ADC 904 may convert the captured audio signal from an analog waveform into a digital waveform consisting of digital audio samples. The processor 910 may process the digital audio samples. The gain adjuster may adjust the digital audio samples. The echo canceller 912 may reduce echo that may have been generated by the output of the speaker 948 input to the microphone 946.

The vocoder encoder 936 may compress the digital audio samples corresponding to the processed voice signal and may form a transmit packet (e.g., a compressed bit representation of the digital audio samples). For example, the transmit packet may correspond to at least a portion of the bitstream 132 of FIG. 1. The transmit packet may be stored in the memory 932. The transceiver 950 may modulate some form of the transmit packet (e.g., may append other information to the transmit packet) and may transmit the modulated data via the antenna 942.

As another example, antenna 942 may receive incoming packets including receive packets. The receive packets may be sent by another device over the network. For example, the receive packets may correspond to at least a portion of bitstream 132 of FIG. 1 . Vocoder decoder 938 may decompress the receive packets. The decompressed waveform may be referred to as a reconstructed audio sample. Echo canceller 912 may remove echo from the reconstructed audio sample.

The processor 910 that carries out speech and music codec 908 can generate high frequency band excitation signal 186, as described with reference to Figures 1 to 8.Processor 910 can generate the output signal 116 of Figure 1 based on high frequency band excitation signal 186.Gain adjuster can amplify or suppress output signal 116.DAC 902 can convert output signal 116 to analog waveform from digital waveform and can be provided to loudspeaker 948 through converted signal.

In conjunction with the described embodiments, an apparatus is disclosed that includes a device for determining a voiced speech classification for an input signal. The input signal may correspond to an audio signal. For example, the device for determining a voiced speech classification may include the voiced speech classifier 160 of FIG. 1 , one or more devices configured to determine the voiced speech classification for the input signal (e.g., a processor executing instructions on a non-transitory computer-readable storage medium), or any combination thereof.

For example, voiced sound classifier 160 can determine parameter 242, described parameter comprises the ratio of the energy of the zero crossing rate of the low-band signal of input signal 130, the first reflection coefficient, the adaptive codebook in the low-band excitation contribution and the energy of the summation that the adaptive codebook in the low-band excitation and fixed codebook contribute, the pitch gain of the low-band signal of input signal 130 or its combination.In a particular embodiment, voiced sound classifier 160 can determine parameter 242 based on the low-band signal 334 of Fig. 3.In an alternative embodiment, voiced sound classifier 160 can extract parameter 242 from the low-band part 232 of the bit stream of Fig. 2.

The voiced speech classifier 160 may determine the voiced speech classification 180 (e.g., the voiced speech factor 236) based on an equation. For example, the voiced speech classifier 160 may determine the voiced speech classification 180 based on Equation 1 and the parameter 242. To illustrate, the voiced speech classifier 160 may determine the voiced speech classification 180 by calculating a weighted sum of a zero-crossing rate, a first reflection coefficient, an energy ratio, a pitch gain, a previous voiced speech decision, a constant value, or a combination thereof, as described with reference to FIG.

The apparatus also includes means for controlling an amount of an envelope of a representation of the input signal based on the voicing classification. For example, the means for controlling the amount of the envelope may include envelope adjuster 162 of FIG. 1 , one or more devices configured to control the amount of the envelope of the representation of the input signal based on the voicing classification (e.g., a processor executing instructions on a non-transitory computer-readable storage medium), or any combination thereof.

For example, envelope adjuster 162 may generate a frequency voicing classification by multiplying voicing classification 180 of FIG. 1 (e.g., voicing factor 236 of FIG. 2 ) by a cutoff frequency scaling factor. The cutoff frequency scaling factor may be a default value. LPF cutoff frequency 426 may correspond to the default cutoff frequency. Envelope adjuster 162 may control the amount of signal envelope 182 by adjusting LPF cutoff frequency 426, as described with reference to FIG. 4 . For example, envelope adjuster 162 may adjust LPF cutoff frequency 426 by adding the frequency voicing classification to LPF cutoff frequency 426.

As another example, the envelope adjuster 162 can generate a bandwidth expansion factor 526 by multiplying the voiced speech classification 180 of FIG. 1 (e.g., the voiced speech factor 236 of FIG. 2 ) by a bandwidth scaling factor. The envelope adjuster 162 can determine the high-band LPC pole associated with the representative signal 422. The envelope adjuster 162 can determine the pole adjustment factor by multiplying the bandwidth expansion factor 526 by the pole scaling factor. The pole scaling factor can be a default value. The envelope adjuster 162 can control the amount of the signal envelope 182 by adjusting the high-band LPC pole, as described with reference to FIG. 5 . For example, the envelope adjuster 162 can adjust the high-band LPC pole to its original state by the pole adjustment factor.

As another example, envelope adjuster 162 may determine the coefficients of the filter. The coefficients of the filter may be default values. Envelope adjuster 162 may determine the filter adjustment factor by multiplying bandwidth expansion factor 526 by a filter scaling factor. The filter scaling factor may be a default value. Envelope adjuster 162 may control the amount of signal envelope 182 by adjusting the coefficients of the filter, as described with reference to FIG6 . For example, envelope adjuster 162 may multiply each of the coefficients of the filter by the filter adjustment factor.

The apparatus further includes means for modulating the white noise signal based on a controlled amount of the envelope. For example, the means for modulating the white noise signal may include modulator 164 of FIG. 1 , one or more devices configured to modulate the white noise signal based on a controlled amount of the envelope (e.g., a processor executing instructions on a non-transitory computer-readable storage medium), or any combination thereof. For example, modulator 164 may determine whether white noise 156 and signal envelope 182 are in the same domain. If white noise 156 is in a different domain than signal envelope 182, modulator 164 may convert white noise 156 to be in the same domain as signal envelope 182 or may convert signal envelope 182 to be in the same domain as white noise 156. Modulator 164 may modulate white noise 156 based on signal envelope 182, as described with reference to FIG. 4 . For example, modulator 164 may multiply white noise 156 and signal envelope 182 in the time domain. As another example, modulator 164 may convolve white noise 156 and signal envelope 182 in the frequency domain.

Equipment also comprises the device that is used for generating high-frequency band excitation signal based on modulated white noise signal.For example, the device that is used to generate high-frequency band excitation signal can comprise the output circuit 166 of Fig. 1, be configured to generate one or more devices (for example, perform the instruction processor at the non-transitory computer-readable storage medium place) of high-frequency band excitation signal based on modulated white noise signal or its any combination.

In a particular embodiment, output circuit 166 can generate high-frequency band excitation signal 186 based on modulated white noise 184, as described with reference to Figures 4 to 7. For example, output circuit 166 can multiply each other through modulated white noise 184 and noise gain 434 to generate the modulated white noise 438 through scaling, as described with reference to Figures 4 to 6. Output circuit 166 can combine the modulated white noise 438 through scaling and another signal (for example, the scaled representative signal 440 of Fig. 4, the scaled filtered signal 540 of Fig. 5 or the scaled synthetic high-frequency band signal 640 of Fig. 6) to generate high-frequency band excitation signal 186.

7 multiplied by the modulated noise gain 732 of modulated white noise 184 and Fig. 7 to generate scaled modulated white noise 740, as described with reference to Figure 7. Output circuit 166 can combine (e.g., add) scaled modulated white noise 740 and scaled unmodulated white noise 742 to generate scaled white noise 744. Output circuit 166 can combine scaled representative signal 440 and scaled white noise 744 to generate high-band excitation signal 186.

Those skilled in the art will further appreciate that the various illustrative logical blocks, configurations, modules, circuits, and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software executed by a processing device (e.g., a hardware processor), or a combination of both. Various illustrative components, blocks, configurations, modules, circuits, and steps have been 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. Those skilled in the art may implement the described functionality in varying ways for each specific application, 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 the two. 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), registers, a hard disk, a removable magnetic disk, or a compact disk 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 a user terminal. Alternatively, the processor and storage medium may reside as discrete components in the computing device or user terminal.

The previous description of the disclosed embodiments is provided to enable those skilled in the art to make or use the disclosed embodiments. Various modifications to these embodiments will be readily apparent to those 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 in the following claims.

Claims (30)

1. A method for generating a high-frequency bandgap excitation signal, comprising: Voiced classification parameters of the input signal are extracted based on the received bitstream, wherein the input signal corresponds to the audio signal; The frequency range of the envelope of the representation of the input signal is controlled based on the voiced sound classification parameters, and the frequency range is controlled based on the cutoff frequency of the low-pass filter applied to the representation of the input signal. A white noise signal is modulated based on the controlled frequency range of the envelope; and The high-frequency excitation signal, corresponding to a decoded version of the audio signal, is generated based on the modulated white noise signal. 2. The method of claim 1, further comprising controlling the magnitude of the envelope. 3. The method of claim 1, further comprising controlling at least one of the shape of the envelope and the gain of the envelope. 4. The method of claim 3, wherein the degree of change in the shape of the envelope is greater when the voiced classification parameter corresponds to a strongly voiced sound compared to when the voiced classification parameter corresponds to a strongly voiced sound. 5. The method according to claim 1, wherein the voiced sound classification parameter indicates that the input signal is a strongly voiced signal, a weakly voiced signal, a weakly unvoiced signal, or a strongly unvoiced signal. 6. The method of claim 1, further comprising determining the cutoff frequency based on the voiced sound classification parameters. 7. The method of claim 1, wherein the cutoff frequency is greater when the voiced classification parameter corresponds to a strongly voiced sound compared to when the voiced sound classification parameter corresponds to a strongly voiced sound. 8. The method of claim 1, wherein the extraction of the voiced classification parameters is performed by a decoder. 9. The method of claim 1, wherein the frequency range of the envelope of the representation of the input signal is controlled by a mobile communication device based on the voiced classification parameters. 10. The method of claim 1, wherein the frequency range of the envelope represented by the input signal is controlled based on the voiced classification parameters via a fixed-position communication unit. 11. The method of claim 1, wherein controlling the frequency range of the envelope of the representation comprises adjusting the representation of the input signal in the transform domain. 12. The method of claim 1, wherein the representation of the input signal comprises a low-frequency band excitation signal of an encoded version of the audio signal or a high-frequency band excitation signal of an encoded version of the audio signal. 13. The method of claim 1, wherein the representation of the input signal comprises a harmonic extended excitation signal, and wherein the harmonic extended excitation signal is generated from a low-frequency band excitation signal of an encoded version of the audio signal. 14. The method of claim 1, further comprising: A scaled white noise signal is generated by combining a scaled unmodulated white noise signal with a scaled modulated white noise signal, wherein the high-frequency band excitation signal is based on the scaled white noise signal. 15. The method of claim 1, wherein the envelope comprises a time-varying envelope, and the method further comprises updating the envelope more than once per frame of the input signal. 16. An apparatus for generating a high-frequency bandgap excitation signal, comprising: A voiced classifier configured to extract voiced classification parameters of an input signal based on a received bitstream, wherein the input signal corresponds to an audio signal; An envelope adjuster configured to control the frequency range of the envelope of the representation of the input signal based on the voiced classification parameters, and to control the frequency range based on the cutoff frequency of a low-pass filter applied to the representation of the input signal; A modulator configured to modulate a white noise signal within a controlled frequency range based on the envelope; and The output circuit is configured to generate the high-frequency band excitation signal based on the modulated white noise signal. 17. The device of claim 16, wherein the envelope adjuster is configured to control at least one of the shape of the envelope, the magnitude of the envelope, and the gain of the envelope based on the voiced classification parameters. 18. The device of claim 17, wherein at least one of the shape of the envelope, the magnitude of the envelope, and the gain of the envelope is controlled by adjusting one or more poles of the linear predictive decoding (LPC) coefficients based on the voiced sound classification parameters. 19. The apparatus of claim 17, wherein at least one of the shape of the envelope, the magnitude of the envelope, and the gain of the envelope is configured to be controlled based on an adjusted coefficient of a filter, the adjusted coefficient being determined based on the voiced classification parameter, and wherein the modulator is configured to apply the filter to the white noise signal to generate the modulated white noise signal. 20. The apparatus of claim 16, further comprising: Antenna; and A receiver coupled to the antenna, the receiver being configured to receive the bit stream. 21. The device of claim 20, wherein the receiver, the voiced classifier, the envelope adjuster, the modulator, and the output circuit are integrated into a mobile communication device. 22. The device of claim 20, wherein the receiver, the voiced classifier, the envelope adjuster, the modulator, and the output circuit are integrated into a fixed-position communication unit. 23. The device according to claim 16, further comprising: A high-frequency band encoder configured to encode the high-frequency band portion of the audio signal based on the high-frequency band excitation signal; and A transmitter configured to transmit an encoded audio signal to another device, wherein the encoded audio signal is an encoded version of the audio signal. 24. A computer-readable storage device storing instructions that, when executed by at least one processor, cause said at least one processor to perform the following operations: Voiced classification parameters of the input signal are extracted based on the received bitstream, wherein the input signal corresponds to the audio signal; The frequency range of the envelope of the representation of the input signal is controlled based on the voiced sound classification parameters, and the frequency range is controlled based on the cutoff frequency of the low-pass filter applied to the representation of the input signal. A white noise signal is modulated based on the controlled frequency range of the envelope; and A high-frequency excitation signal is generated based on the modulated white noise signal. 25. The computer-readable storage device of claim 24, wherein the instructions are further executable to cause the at least one processor to control the shape of the envelope based on the voiced classification parameters. 26. The computer-readable storage device of claim 24, wherein the instructions are further executable to cause the at least one processor to control at least one of the magnitude of the envelope and the gain of the envelope. 27. An apparatus for generating a high-frequency bandgap excitation signal, comprising: Apparatus for extracting voiced classification parameters of an input signal based on a received bitstream, wherein the input signal corresponds to an audio signal; A means for controlling the frequency range of the envelope of a representation of an input signal based on the voiced classification parameters, wherein the frequency range is controlled based on the cutoff frequency of a low-pass filter applied to the representation of the input signal; A means for modulating a white noise signal based on a controlled frequency range of the envelope; and A means for generating the high-frequency band excitation signal based on a modulated white noise signal. 28. The apparatus of claim 27, wherein the representation of the input signal includes a low-frequency band excitation signal of the input signal, a high-frequency band excitation signal of the input signal, or a harmonic extended excitation signal, and wherein the harmonic extended excitation signal is generated from the low-frequency band excitation signal of the input signal. 29. The device of claim 27, wherein the means for extraction, the means for control, the means for modulation, and the means for generation are integrated in a mobile communication device. 30. The device of claim 27, wherein the means for extraction, the means for control, the means for modulation, and the means for generation are integrated in a fixed-position communication unit.