Audio signal encoding and decoding method, and audio signal encoding and decoding apparatus
An audio signal encoding and decoding method, an audio signal encoding and decoding apparatus, a transmitter, a receiver, and a communications system, which can improve encoding and/or decoding performance. The audio signal encoding method includes dividing a to-be-encoded time domain signal into a low band signal and a high band signal; encoding the low band signal to obtain a low frequency encoding parameter; calculating a voiced degree factor, and predicting a high band excitation signal; weighting the high band excitation signal and random noise using the voiced degree factor, so as to obtain a synthesized excitation signal; and obtaining a high frequency encoding parameter based on the synthesized excitation signal and the high band signal. Technical solutions in the embodiments of the present invention can improve an encoding or decoding effect.
1. An audio signal encoding method, comprising:
dividing a time domain audio signal into a low band signal and a high band signal;
encoding the low band signal to obtain one or more low frequency encoding parameters;
calculating a voiced degree factor according to the low frequency encoding parameters;
predicting a high band excitation signal according to the low frequency encoding parameters;
obtaining a synthesized excitation signal according to the high band excitation signal and the voiced degree factor; and
obtaining one or more high frequency encoding parameters based on the synthesized excitation signal and the high band signal;
wherein the low frequency encoding parameters comprise an algebraic codebook, an algebraic codebook gain, and a pitch period, and wherein predicting the high band excitation signal according to the low frequency encoding parameters comprises:
modifying the voiced degree factor using the pitch period;
obtaining a weighted sum of the algebraic codebook and random noise using the modified voiced degree factor as a weighting factor; and
obtaining the high band excitation signal according to the weighted sum and the algebraic codebook gain.
2. The method according to claim 1 , wherein modifying the voiced degree factor using the pitch period is performed according to the following formula:
voice_fac_ A =voice_fac× y
y=−a 1× T 0+ b 1, T 0≦threshold_min
wherein voice_fac is the voiced degree factor, T0 is the pitch period, a1 and b1≧0, threshold_min is a preset minimum value of the pitch period, and voice_fac_A is the modified voiced degree factor.
3. The method according to claim 1 , further comprising:
generating an encoded bitstream according to the low frequency encoding parameters and the high frequency encoding parameters; and
sending the encoded bitstream to a decoder side.
4. An audio signal encoding method, comprising:
dividing a time domain audio signal into a low band signal and a high band signal;
encoding the low band signal to obtain one or more low frequency encoding parameters;
calculating a voiced degree factor according to the low frequency encoding parameters;
predicting a high band excitation signal according to the low frequency encoding parameters;
obtaining a synthesized excitation signal according to the high band excitation signal and the voiced degree factor; and
obtaining one or more high frequency encoding parameters based on the synthesized excitation signal and the high band signal;
wherein the low frequency encoding parameters comprise an algebraic codebook, an algebraic codebook gain, an adaptive codebook, an adaptive codebook gain, and a pitch period, and wherein predicting the high band excitation signal according to the low frequency encoding parameters comprises:
modifying the voiced degree factor using the pitch period to obtain a modified voiced degree factor;
obtaining a weighted sum of the algebraic codebook and random noise using the modified voiced degree factor as a weighting factor; and
obtaining the high band excitation signal by adding a product of the weighted sum and the algebraic codebook gain and a product of the adaptive codebook and the adaptive codebook gain.
5. The method according to claim 4 , further comprising:
generating an encoded bitstream according to the low frequency encoding parameters and the high frequency encoding parameters; and
sending the encoded bitstream to a decoder side.
6. An audio signal encoding apparatus comprising:
a processor and a memory storing computer-readable instructions for execution by the processor;
wherein the processor is configured to execute the instructions to:
divide a time domain signal into a low band signal and a high band signal;
encode the low band signal to obtain one or more low frequency encoding parameters;
calculate a voiced degree factor according to the low frequency encoding parameters;
predict a high band excitation signal according to the low frequency encoding parameters;
obtain a synthesized excitation signal according to the high band excitation signal and the voiced degree factor; and
obtain one or more high frequency encoding parameters based on the synthesized excitation signal and the high band signal;
wherein the low frequency encoding parameters comprise an algebraic codebook, an algebraic codebook gain, an adaptive codebook, an adaptive codebook gain, and a pitch period, and in predicting the high band excitation signal according to the low frequency encoding parameters, the processor is configured to execute the instructions to:
modify the voiced degree factor using the pitch period to obtain a modified voiced degree factor; and
obtain a weighted sum of the algebraic codebook and random noise using the modified voiced degree factor as a weighting factor; and
obtain the high band excitation signal by adding a product of the weighted sum and the algebraic codebook gain and a product of the adaptive codebook and the adaptive codebook gain.