Gain quantization system for speech coding to improve packet loss concealment
In order to recover the excitation energy quickly and keep the adaptive excitation contribution percentage in the entire excitation after bit-stream packet loss, the two excitation gains (G p 305 and G c 306 ) can be first transformed into the two other special parameters: one is the entire excitation energy and another is the energy ratio of the adaptive excitation contribution portion relative to the entire excitation energy. Then, the transformed parameters are quantized and sent to decoder. At the decoder side, the quantized parameters are transformed back to the original form of the gains (G p 305 and G c 306 ).
1. A speech or signal coding method for encoding a speech signal or a general signal and improving packet loss concealment, the coding method comprising:
coding energies of two excitation components of an excitation e(n), the two excitation components comprising a first excitation component and a second excitation component, wherein the first excitation component generated by multiplying an adaptive codebook vector e p (n) with a gain G p is called an adaptive codebook excitation component, a pitch contribution excitation component or an excitation component contributed from a past synthesized excitation, wherein the second excitation component generated by multiplying a fixed codebook vector e c (n) with a gain G c , is called a fixed codebook excitation component or a current excitation component contribution, and wherein the excitation e(n) is a linear combination of the two excitation components;
transforming the two gains {G p , G c } into other two parameters noted as {Ē e , R p } wherein the parameter Ē e represents a function of energy of the excitation e(n) or a function of energies of both the first excitation component and the second excitation component within a subframe of a frame of signal, and the other parameter R p represents a ratio of an energy of one of the two excitation components relative to Ē e ;
encoding the two parameters {Ē e , R p } at an encoder; and
decoding the two parameters {Ē e , R p } at a decoder.
2. The method of claim 1 , comprising a Code-Excited Linear Prediction (CELP) technology.
3. The method of claim 1 , wherein the function of energy of the excitation e(n) is an average excitation energy calculated by summing an energy of each of a plurality of samples of the excitation e(n) within the subframe and dividing the summed energy by a subframe size of the subframe, defined as the following:
E
_
e
=
e
(
n
)
2
/
L_sub
=
1
L_sub
∑
n
e
(
n
)
2
L_sub is the subframe size.
4. The method of claim 1 , wherein the function of energy of the excitation e(n) is an entire excitation energy calculated by summing an energy of each of a plurality of samples of the excitation e(n) within the subframe, defined as the following:
E
_
e
=
e
(
n
)
2
=
∑
n
e
(
n
)
2
.
5. The method of claim 1 , wherein the function of energies of both the first excitation component and the second excitation component is a combined excitation energy calculated by summing an energy of the first excitation component and an energy of the second excitation component within the subframe, defined as the following:
E
_
e
=
G
p
2
·
e
p
(
n
)
2
+
G
c
2
·
e
c
(
n
)
2
or
E
_
e
=
{
G
p
2
·
e
p
(
n
)
2
+
G
c
2
·
e
c
(
n
)
2
}
/
L_sub
L _sub is a subframe size of the subframe.
6. The method of claim 1 , wherein the ratio R p is defined as the following:
R
p
=
G
p
2
·
e
p
(
n
)
2
G
p
2
·
e
p
(
n
)
2
+
G
c
2
·
e
c
(
n
)
2
or
R
p
=
G
c
2
·
e
c
(
n
)
2
G
p
2
·
e
p
(
n
)
2
+
G
c
2
·
e
c
(
n
)
2
where G p 2 ·∥e p (n)∥ 2 is an energy of the first excitation component within the subframe and G c 2 ·∥e c (n)∥ 2 is an energy of the second excitation component within the subframe.
7. The method of claim 1 , wherein the ratio R p is defined as the following:
R
p
=
G
p
2
·
e
p
(
n
)
2
e
(
n
)
2
or
R
p
=
G
c
2
·
e
c
(
n
)
2
e
(
n
)
2
where G p 2 ·∥e p (n)∥ 2 is an energy of the first excitation component within the subframe, G c 2 ·∥e c (n)∥ 2 is an energy of the second excitation component within the subframe, and ∥e(n)∥ 2 is an energy of the excitation e(n) within the subframe.
8. The method of claim 1 further comprising the steps of:
quantizing the two parameters {Ē e , R p } at the encoder to obtain quantization indexes;
sending the quantization indexes to the decoder;
decoding the two parameters {Ē e , R p } by using the quantization indexes at the decoder;
transforming the two parameters {Ē e , R p } back to the two gains {G p , G c } at the decoder; and
reconstructing the excitation e(n) by using the two gains {G p , G c } as the following:
e ( n ) = G p ·e p ( n )+G c ·e c ( n ).