摘要:
A method and apparatus to search a codebook including pulses that model a predetermined component of a speech signal. The method includes the operations of selecting a predetermined number of paths corresponding to a predetermined number of pulse locations that are most consistent with the predetermined component, from among paths corresponding to pulse locations of a predetermined pulse location set allocated to at least one branch that connects one state of a predetermined Trellis structure to another state, performing the path selecting operation on each of states other than the one state, and selecting a path corresponding to pulse locations that are most consistent with the predetermined component, from among paths including the selected paths, wherein each path corresponds to a union of plural tracks of an Algebraic codebook. Accordingly, the number of calculations required during a codebook search is reduced.
摘要:
A coding method is adapted to select different codebook search algorithms according to varied types of input signals. An encoder using the coding method is also provided. As appropriate search algorithms may be selected according to all possible structural features of the input signals, certain types of signals for which satisfactory results may be obtained through simple computations may match with search algorithms suitable for these signal types and having low computation complexities, so as to achieve better performance with fewer system resources. Meanwhile, other types of signals that need complicated computations may be processed by more sophisticated search algorithms, thereby ensuring the coding quality.
摘要:
According to the present invention, a linear prediction filter coefficient of a current frame is acquired from an input signal using linear prediction, a quantized spectrum candidate vector of the current frame, corresponding to the linear prediction filter coefficient of the current frame, is acquired on the basis of first best information, and the quantized spectrum candidate vector of the current frame and the quantized spectrum vector of the previous frame are interpolated. Accordingly, in contrast to conventional phased optimization techniques, optimum parameters which minimize quantization errors, can be obtained.
摘要:
The present research can decrease the amount of computation and enhance speech quality by using a global pulse replacement method in a fixed codebook search. The fixed codebook search method in a speech encoder based upon global pulse replacement, includes the steps of: (a) computing absolute values of the pulse-position likelihood-estimator vectors; (b) temporarily obtaining a codebook vector; (c) computing a mathematical equation by replacing a pulse; (d) determining whether a value computed based upon the mathematical equation is increased after pulse replacement; (e) obtaining a new codebook vector by replacing the pulse; and (f) maintaining a previous codebook vector.
摘要:
The present research can decrease the amount of computation and enhance speech quality by using a global pulse replacement method in a fixed codebook search. The fixed codebook search method in a speech encoder based upon global pulse replacement, includes the steps of: (a) computing absolute values of the pulse-position likelihood-estimator vectors; (b) temporarily obtaining a codebook vector; (c) computing a mathematical equation by replacing a pulse; (d) determining whether a value computed based upon the mathematical equation is increased after pulse replacement; (e) obtaining a new codebook vector by replacing the pulse; and (f) maintaining a previous codebook vector.
摘要:
A method comprises identifying a component k of a codevector from a codebook C having one or more codevectors, the component k introducing highest variance for an input vector; allowing ordering of codevectors in the codebook C; and searching for a best match vector for the input vector using ordered codevectors.
摘要:
A sub-quantizer for sub-quantization of a vector includes a sub-codevector generator that generates a set of candidate sub-codevectors, and transformation logic that transforms each candidate sub-codevector into a corresponding codevector. A memory stores an illegal space definition representing illegal vectors. A legal status tester determines legal codevectors among the codevectors based on the illegal space definition. An error calculator generates error terms corresponding to the candidate sub-codevector, and a sub-codevector selector determines a best one of the sub-codevectors corresponding to a legal codevector and a best error term. The vector includes parameters relating to a speech and/or audio signal, such as Line Spectral Frequencies (LSFs).
摘要:
An excitation vector generator includes an input vector providing system that is capable of providing an input vector having at least one pulse, each pulse having a predetermined position and a respective polarity. A fixed waveform storage system is capable of storing at least one fixed waveform. An arranging system is capable of arranging the at least one fixed waveform in accordance with the position and the polarity of the at least one pulse.
摘要:
An excitation signal coding apparatus capable of improving an error resilience by changing an excitation vector search method (more specifically, an error minimization criterion during a search). This coding apparatus is allowed to choose either of an ordinary search method and the search method of the present invention with using information input from a transmission channel condition monitoring section (215). That is, an ordinary search method is used when the transmission channel condition is good and no packet discarding is observed on the receiving side, and the search method of the present invention is used otherwise (when packet discarding is observed on the receiving side at a discarding rate of 5% or more, for example).
摘要:
ITU Recommendation G.729 Annex E teaches in the implementation of a fixed codebook search to determine the selected sample combination providing the minimal difference between the original input speech and the reconstructed speech after implementation of the codec. A large number of sample sets are processed and the difference between the original input signal and the reconstructed signal for each set is determined and stored in a register. Under certain conditions, the register can overflow resulting in invalid difference values. When such a condition occurs, the fixed codebook search cannot determine the sample combination providing the minimal mean square error between the weighted input speech and the weighted reconstructed speech. An initialization vector for the codvec vector is used to provide valid data which conforms to the G.729 Annex E specifications and minimizes changes to the G.729 source code while providing robust quality signal processing in the event of register overflow condition.