Patent ID: 11894007
Assignee: HUAWEI TECHNOLOGIES CO., LTD.
Field: Computer technology (Electrical engineering)
Classification: CPC G | IPC G

Claim 19:
20. The audio signal encoder of claim 19, wherein when executed by the one or more processors, the program instructions cause the audio signal encoder to be further configured to:
calculate the smoothed energy ratio according to the adjusted energy ratio according to the following third equation:

LF_EnergyRatio_sm⇐(15·LF_EnergyRatio_sm+Ratio)/16,

wherein LF_EnergyRatio_sm on a left side of the third equation is the smoothed energy ratio of the current frame, wherein LF_EnergyRatio_sm on a right side of the third equation is the smoothed energy ratio of a previous frame, and wherein Ratio is the adjusted energy ratio,
wherein the average normalized pitch correlation is obtained by calculating the average normalized pitch correlation as:

Voicing=[R1(P+R2(P2)+R3(P3)+R4(P4)]/4,

wherein Voicing is the average normalized pitch correlation, R1(P1), R2(P2), R3(P3), wherein R4(P4) are four normalized pitch correlations calculated for four subframes of the current frame, wherein P1, P2, P3, and P4 are four pitch candidates found in a pitch range from PIT_MIN to PIT_MAX and respectively corresponding to R1(P1), R2(P2), R3(P3), wherein PIT_MIN is the first minimum pitch limitation, and wherein PIT_MAX is a pitch limitation greater than the first minimum pitch limitation, and
wherein when executed by the one or more processors, the program instructions cause the audio signal encoder to determine the value of the initial pitch lag candidate as:

R(Pitch_Tp)=MAX{R(P),P=PIT_MIN0, . . . ,PIT_MIN},

wherein R(P) is a normalized pitch correlation for a pitch lag P, Pitch_Tp is the value of the initial pitch lag candidate, wherein PIT_MIN0 is the second minimum pitch limitation, and wherein PIT_MIN is the first minimum pitch limitation,
wherein the one or more conditions further comprise a first smoothed pitch correlation of the initial pitch lag candidate of the current frame is greater than a third threshold and the first smoothed pitch correlation is greater than a value of a fourth threshold multiplied by a third smoothed pitch correlation of the current frame,
wherein the first smooth pitch correlation is calculated according to the following fourth equation:

Voicing0_sm⇐(3·Voicing0_sm+Voicing0)/4

wherein Voicing0_sm on a left side of the fourth equation is the first smoothed pitch correlation, wherein Voicing0_sm on a right side of the fourth equation is a second smoothed pitch correlation of the initial pitch lag candidate of a previous frame, and wherein Voicing0 is equal to a normalized pitch correlation of the initial pitch lag candidate,
wherein the third smoothed pitch correlation is calculated according to the following fifth equation:

Voicing_sm⇐(3·Voicing_sm+Voicing)/4,

wherein Voicing_sm on a left side of the fifth equation is the third smoothed pitch correlation, wherein Voicing_sm on a right side of the fifth equation is a fourth smoothed pitch correlation of a previous frame, and wherein Voicing is the average normalized pitch correlation.