Pitch prediction for packet loss concealment
View Patent ↗There is provided a pitch lag predictor for use by a speech decoder to generate a predicted pitch lag parameter. The pitch lag predictor comprises a summation calculator configured to generate a first summation based on a plurality of previous pitch lag parameters, and a second summation based on a plurality of previous pitch lag parameters and a position of each of the plurality of previous pitch lag parameters with respect to the predicted pitch lag parameter; a coefficient calculator configured to generate a first coefficient using a first equation based on the first summation and the second summation, and a second coefficient using a second equation based on the first summation and the second summation, wherein the first equation is different than the second equation; and a predictor configured to generate the predicted pitch lag parameter based on the first coefficient and the second coefficient.
1. A pitch lag prediction method for use by a speech decoder to generate a predicted pitch lag parameter, the pitch lag prediction method comprising:
generating a first summation based on a plurality of previous pitch lag parameters, from previously received speech frames by the speech decoder, wherein the first summation is defined by
sum
0
=
∑
i
=
0
n
-
1
P
(
i
)
,
where n is the number of the plurality of previous pitch lag parameters defined by P(i);
generating a second summation based on the plurality of previous pitch lag parameters and a position of each of the plurality of previous pitch lag parameters with respect to the predicted pitch lag parameter, wherein the second summation is defined by
sum
1
=
∑
i
=
0
n
-
1
i
*
P
(
i
)
;
calculating a first coefficient using a first equation based on the first summation and the second summation, wherein the first equation is defined by a=(3*sum 0 −sum 1 )/5;
calculating a second coefficient using a second equation based on the first summation and the second summation, wherein the second equation is defined by b=(sum 1 −2*sum 0 )/10;
predicting the predicted pitch lag parameter based on the first coefficient and the second coefficient; and
generating a decoded speech signal using the predicted pitch lag parameter.
2. The pitch lag prediction method of claim 1 , wherein the predicting includes generating the predicted pitch lag parameter by adding the first coefficient to a result of the second coefficient multiplied by n.
3. The pitch lag prediction method of claim 1 , wherein the first equation and the second equation are obtained by setting
∂
E
∂
a
and
∂
E
∂
b
to zero, where P′(i) defines the predicted pitch lag parameter and where:
E
=
∑
i
=
0
n
-
1
[
(
P
′
(
i
)
-
P
(
i
)
]
2
=
∑
i
=
0
n
-
1
[
(
a
+
b
*
i
)
-
P
(
i
)
]
2
.
4. The pitch lag prediction method of claim 3 , wherein the predicting includes generating the predicted pitch lag parameter by adding the first coefficient to a result of the second coefficient multiplied by n.