Audio signal processing method and encoder

Patent metadata

Field	Value
Publication number	US-9792257-B2
Application number	US-201615345074-A
Country	US
Kind code	B2
Filing date	Nov 7, 2016
Priority date	Jan 10, 2011
Publication date	Oct 17, 2017
Grant date	Oct 17, 2017

Abstract

An embodiment of the present invention discloses a data processing method, including: twiddling input data, so as to obtain twiddled data; pre-rotating the twiddled data by using a symmetric rotate factor, where the rotate factor is a·W 4L 2p+1 , p=0, . . . , L/2−1, and a is a constant; performing a Fast Fourier (Fast Fourier Transform, FFT) transform of L/2 point on the pre-rotated data, where L is the length of the input data; post-rotating the data that has undergone the FFT transform by using a symmetric rotate factor, where the rotate factor is b·W 4L 2q+1 , q=0, . . . , L/2−1, and b is a constant; and obtaining output data.

First claim

What is claimed is:

1. A method for processing an audio signal, the method comprising:
obtaining, by an encoder comprising a processor, a windowed time domain data by windowing an input audio signal;
obtaining, by the encoder, a twiddled signal based on the windowed time domain data;
pre-rotating, by the encoder, the twiddled signal by using a first symmetric rotation factor to obtain a pre-rotated data, wherein the first symmetric rotation factor is a·W 4L 2p+1 , p=0, . . . , L/2−1, wherein a is a constant, wherein L is the length of the input audio signal;
performing, by the encoder, a Fast Fourier transform (FFT) of L/2 points on the pre-rotated data to obtain FFT data;
performing, by the encoder, an in-place fixed rotate compensation on the FFT data;
post-rotating, by the encoder, the data that has undergone the in-place fixed rotate compensation by using a second symmetric rotation factor to obtain a post-rotated data, wherein the second symmetric rotation factor is b·W 4L 2p+1 , q=L/2−1, and b is a constant;
quantizing, by the encoder, a signal derived from the post-rotated data to obtain a quantized signal; and
writing, by the encoder, the quantized signal into a bitstream for transmitting or storing.

2. The method according to claim 1 , wherein the in-place fixed rotate compensation is performed by multiplying a fixed rotate compensation factor with the FFT data.

3. The method according to claim 2 , wherein the fixed rotate compensation factor is

1
+

j
⁡

(

3
⁢
π

4
⁢

⁢
L

)

.

4. The method according to claim 1 , wherein the twiddled signal is obtained according to z(p)={tilde over (x)}(2p)+j·{tilde over (x)}(L−1−2p), wherein z(p) denotes the twiddled signal, {tilde over (x)}(n) denotes the windowed time domain data.

5. The method according to claim 1 , wherein W 4L 2q+1 in the first symmetric rotation factor is expressed in the following form:

W

4
⁢
L

2
⁢
p

+
1

=

cos
⁢

⁢

2
⁢
π
⁢

(

2
⁢
p

+
1

)

4
⁢
L

-

j
⁢

⁢
sin
⁢

⁢

2
⁢

π
⁡

(

2
⁢
p

+
1

)

4
⁢
L

.

6. The method according to claim 1 , wherein W 4L 2q+1 in the second symmetric rotation factor is expressed in the following form:

W

4
⁢
L

2
⁢
p

+
1

=

cos
⁢

⁢

2
⁢

π
⁡

(

2
⁢
p

+
1

)

4
⁢
L

-

j
⁢

⁢
sin
⁢

⁢

2
⁢

π
⁡

(

2
⁢
p

+
1

)

4
⁢
L

Assignees

• Huawei Tech Co Ltd

Inventors

• Zhang Deming
• Li Haiting
• Taleb Anisse
• Xu Jianfeng

Classifications

• G10L19/022

  Blocking, i.e. grouping of samples in time; Choice of analysis windows; Overlap factoring · CPC title

• G06F17/141

  Discrete Fourier transforms · CPC title

• G06F17/142 Primary

  Fast Fourier transforms, e.g. using a Cooley-Tukey type algorithm · CPC title

• G10L19/0212

  using orthogonal transformation · CPC title

• G06F17/147 Primary

  Discrete orthonormal transforms, e.g. discrete cosine transform, discrete sine transform, and variations therefrom, e.g. modified discrete cosine transform, integer transforms approximating the discrete cosine transform (G06F17/145 takes precedence) · CPC title