Coding device, communication processing device, and coding method
View Patent ↗Provided are a coding device, a communication processing device, and a coding method, whereby processing operation load (computational load) is significantly reduced for a configuration which computes either frame energy or sub-frame energy of an input signal, using auto-correlation operations, without causing a decline in the precision of either the frame energy or the sub-frame energy. In a coding device ( 101 ), a sub-frame energy computation unit ( 201 ) computes the sub-frame energy by substituting the sum of input signal auto-correlation operations in a first range with the sum of auto-correlation operations in a second range which differs at least partially from the first range.
1. A coding apparatus, comprising:
a memory;
a receiver that receives a speech/sound signal;
an energy processor that divides the speech/sound signal into subframes and that calculates one of frame energy and subframe energy of the speech/sound signal using an auto-correlation operation of the speech/sound signal;
an encoder that encodes the speech/sound signal divided into subframes using one of the frame energy and the subframe energy, and generates encoded speech/sound information; and
a transmitter that transmits the encoded speech/sound information over a communication channel to a decoding apparatus,
wherein the coding apparatus performs auto-correlation operations that substantially reduce processing calculations without causing deterioration of the accuracy of the frame energy and the subframe energy,
wherein, when performing an auto-correlation operation on the speech/sound signal using equation 1 or equation 2, the energy processor performs auto-correlation operations at j′ and m′ which are different from j and m in accordance with the values of j and m, and calculates one of the frame energy and the subframe energy by substituting the auto-correlation operations at j and m with the auto-correlation operations at j′ and m′:
(
Equation
1
)
E
k
=
∑
i
A
i
2
=
∑
j
=
0
P
-
1
∑
m
=
0
P
-
1
α
j
α
m
∑
i
x
i
-
j
x
i
-
m
(
i
=
start
k
,
…
,
end
k
k
=
0
,
…
,
N
S
-
1
)
[
1
]
E k : energy (subframe energy) of subframe whose subframe index is k,
A i : speech/sound signal after filtering,
P: filter order,
α j , αm: filter coefficient,
x n : (n+1)-th speech/sound signal of subframe,
j, m: index indicating delay time when auto-correlation is calculated,
i: sample index of speech/sound signal,
N s : number of subframes,
k: subframe index,
start k : leading sample index of subframe whose subframe index is k, and
end k : tail-end sample index of subframe whose subframe index is k; and
(
Equation
2
)
E
=
∑
i
A
i
2
=
∑
j
=
0
P
-
1
∑
m
=
0
P
-
1
α
j
α
m
∑
i
x
i
-
j
x
i
-
m
(
i
=
start
,
…
,
end
)
[
2
]
E: frame energy,
A i : speech/sound signal after filtering,
P: filter order,
α j , αm: filter coefficient,
x n : (n+1)-th speech/sound signal of frame,
j, m: index indicating delay time when auto-correlation is calculated,
i: sample index of speech/sound signal,
start: leading sample index of frame, and
end: tail-end sample index of frame, and
wherein the energy processor performs control so as to increase the number of combinations of j and m to be substituted with auto-correlation operations at j′ and m′ as the difference between j and m in equation 1 or equation 2 increases.
2. The coding apparatus according to claim 1 ,
wherein the energy processor substitutes the auto-correlation operations at j and m including a sample in which the amplitude of the speech/sound signal is equal to or greater than a threshold with the auto-correlation operations at j′ and m′ including a sample in which the amplitude of the speech/sound signal is equal to or greater than the threshold.
3. The coding apparatus according to claim 1 ,
wherein the energy processor sets, as a division point, a point having a maximum variation of an auto-correlation value for each sample for a range in which an auto-correlation operation is performed and substitutes the auto-correlation operations at j and m with the auto-correlation operations at j′ and m′ before and after the division point.
4. The coding apparatus according to claim 1 ,
wherein, when the variation in the amplitude of the sample within a frame or subframe is large, the energy processor substitutes the auto-correlation operations at j and m with auto-correlation operations at j′ and m′ including a sample with small amplitude.
5. The coding apparatus according to claim 1 ,
wherein the energy processor substitutes the auto-correlation operations at j and m with the auto-correlation operations at one combination of j′ and m′ whose difference is equal to the difference between j and m.
6. A communication terminal apparatus, comprising the coding apparatus according to claim 1 .
7. A base station apparatus comprising, the coding apparatus according to claim 1 .
8. A coding method comprising:
receiving, by a receiver, a speech/sound signal;
dividing, by an energy processor, the speech/sound signal into subframes;
calculating, by the energy processor, one of frame energy and subframe energy of a speech/sound signal using an auto-correlation operations of the speech/sound signal;
encoding, by an encoder, the speech/sound signal divided into subframes using one of the frame energy and the subframe energy, and generating speech/sound encoded information; and
transmitting, by a transmitter, the encoded speech/sound information over a communication channel to a decoding apparatus,
wherein the coding method performs auto-correlation operations that substantially reduce processing calculations without causing deterioration of the accuracy of the frame energy and the subframe energy,
wherein in the calculating, when performing an auto-correlation operation on the speech/sound signal using equation 1 or equation 2, auto-correlation operations at j′ and m′ which are different from j and m in accordance with the values of j and m are performed, and one of the frame energy and the subframe energy is calculated by substituting the auto-correlation operations at j and m with the auto-correlation operations at j′ and m′:
(
Equation
1
)
E
k
=
∑
i
A
i
2
=
∑
j
=
0
P
-
1
∑
m
=
0
P
-
1
α
j
α
m
∑
i
x
i
-
j
x
i
-
m
(
i
=
start
k
,
…
,
end
k
k
=
0
,
…
,
N
S
-
1
)
[
1
]
E k : energy (subframe energy) of subframe whose subframe index is k,
A i : speech/sound signal after filtering,
P: filter order,
α j , α m : filter coefficient,
x n : (n+1)-th speech/sound signal of subframe,
j, m: index indicating delay time when auto-correlation is calculated,
i: sample index of speech/sound signal,
N s : number of subframes,
k: subframe index,
start k : leading sample index of subframe whose subframe index is k, and
end k : tail-end sample index of subframe whose subframe index is k; and
(
Equation
2
)
E
=
∑
i
A
i
2
=
∑
j
=
0
P
-
1
∑
m
=
0
P
-
1
α
j
α
m
∑
i
x
i
-
j
x
i
-
m
(
i
=
start
,
…
,
end
)
[
2
]
E: frame energy,
A i : speech/sound signal after filtering,
P: filter order,
α j , α m : filter coefficient,
x n : (n+1)-th speech/sound signal of frame,
j, m: index indicating delay time when auto-correlation is calculated,
i: sample index of speech/sound signal,
start: leading sample index of frame, and
end: tail-end sample index of frame, and
wherein, in the calculating, control is performed so as to increase the number of combinations of j and m to be substituted with auto-correlation operations at j′ and m′ as the difference between j and m in equation 1 or equation 2 increases.