Audio coding method and apparatus
A method comprises determining a first modification weight according to linear spectral frequency (LSF) differences of the current frame and LSF differences of a previous frame of the current frame, when a signal characteristic of the current frame meets a preset modification condition, modifying the linear predictive parameter of the current frame according to the determined first modification weight, and coding the current frame according to the modified linear predictive parameter.
1. A computer program product comprising a non-transitory computer readable medium storing computer-executable instructions that, when executed by a processor of a device, cause the device to:
determine whether a signal characteristic of a current frame of an audio signal meets a preset modification condition;
determine a first modification weight according to linear spectral frequency (LSF) differences of the current frame and LSF differences of a previous frame of the audio signal in response to the signal characteristic of the current frame meeting the preset modification condition;
modify a linear predictive parameter of the current frame according to the first modification weight to obtain a modified linear predictive parameter; and
code the current frame according to the modified linear predictive parameter.
2. The computer program product of claim 1 , wherein before modifying the linear predictive parameter of the current frame, the instructions further cause the device to perform linear prediction analysis on the audio signal to obtain the linear predictive parameter.
3. The computer program product of claim 1 , wherein the first modification weight is determined according to the formula:
w
[
i
]
=
{
lsf_new
_diff
[
i
]
/
lsf_old
_diff
[
i
]
,
lsf_new
_diff
[
i
]
<
lsf_old
_diff
[
i
]
lsf_old
_diff
[
i
]
/
lsf_new
_diff
[
i
]
,
lsf_new
_diff
[
i
]
≥
lsf_old
_diff
[
i
]
,
wherein w[i] is the first modification weight, wherein lsf_new_diff[i] is the LSF differences of the current frame, wherein lsf_old_diff[i] is the LSF differences of the previous frame, and wherein i is an integer.
4. The computer program product of claim 3 , wherein i is an integer value ranging from 0 to 9.
5. The computer program product of claim 3 , wherein i is an integer value ranging from 1 to 8.
6. The computer program product of claim 1 , wherein the linear predictive parameter of the current frame is modified according to the formula:
L [ i ]=(1 −w [ i ])* L _ old [ i ]+ w [ i ]* L _ new [ i ],
wherein L[i] is the modified linear predictive parameter of the current frame,
wherein w[i] is the first modification weight, wherein L_new[i] is the linear predictive parameter of the current frame, wherein L_old[i] is a linear predictive parameter of the previous frame of the current frame, and wherein i is an integer.
7. The computer program product of claim 6 , wherein i is an integer value ranging from 0 to 9.
8. The computer program product of claim 1 , wherein the signal characteristic of the current frame meets the preset modification condition when the current frame is not a transition frame.
9. The computer program product of claim 8 , wherein the current frame is a transition frame when a tilt of a previous frame is greater than a tilt threshold value and a coder type of the current frame is a transient.
10. The computer program product of claim 8 , wherein the current frame is a transition frame when a tilt of the previous frame is greater than a first tilt threshold value and a tilt of the current frame is less than a second tilt threshold value.
11. The computer program product of claim 8 , wherein the current frame is a transition frame when a tilt of the previous frame is less than a first tilt threshold value and when the previous frame has a voiced, generic, transition, or audio coding, and wherein a tilt of the current frame is greater than a second tilt threshold value.
12. The computer program product of claim 1 , wherein the instructions further cause the device to:
determine a second modification weight in response to the signal characteristic of the current frame not meeting the preset modification condition; and
modify the linear predictive parameter of the current frame according to the second modification weight.
13. The computer program product of claim 12 , wherein the instructions further cause the device to determine a preset modification weight value as the second modification weight, and wherein the preset modification weight value is greater than 0 and less than or equal to 1.
14. The computer program product of claim 13 , wherein the preset modification weight value is 0.5.
15. An audio coding apparatus comprising:
a memory storing instructions; and
a processor coupled to the memory and configured to execute the instructions, which cause the processor to be configured to:
determine whether a signal characteristic of a current frame of an audio signal meets a preset modification condition;
determine a first modification weight according to linear spectral frequency (LSF) differences of the current frame and LSF differences of a previous frame of the audio signal in response to the signal characteristic meeting the preset modification condition;
modify a linear predictive parameter of the current frame according to the first modification weight to obtain a modified linear predictive parameter; and
code the current frame according to the modified linear predictive parameter.
16. The apparatus of claim 15 , wherein the signal characteristic meets the preset modification condition when the current frame is not a transition frame.
17. The apparatus of claim 15 , wherein the first modification weight is determined according to the formula:
w
[
i
]
=
{
lsf_new
_diff
[
i
]
/
lsf_old
_diff
[
i
]
,
lsf_new
_diff
[
i
]
<
lsf_old
_diff
[
i
]
lsf_old
_diff
[
i
]
/
lsf_new
_diff
[
i
]
,
lsf_new
_diff
[
i
]
≥
lsf_old
_diff
[
i
]
,
wherein w[i] is the first modification weight, wherein lsf_new_diff[i] is the LSF differences of the current frame, wherein lsf_old_diff[i] is the LSF differences of the previous frame, and wherein i is an integer.
18. The apparatus of claim 17 , wherein i is an integer value ranging from 0 to 9.
19. The apparatus of claim 17 , wherein i is an integer value ranging from 1 to 8.
20. The apparatus of claim 15 , wherein the linear predictive parameter of the current frame is modified according to the formula:
L [ i ]=(1 −w [ i ])* L _ old [ i ]+ w [ i ]* L _ new [ i ],
wherein L[i] is the modified linear predictive parameter of the current frame,
wherein w[i] is the first modification weight, wherein L_new[i] is the linear predictive parameter of the current frame, wherein L_old[i] is a linear predictive parameter of the previous frame of the current frame, and wherein i is an integer.