LPC residual signal encoding/decoding apparatus of modified discrete cosine transform (MDCT)-based unified voice/audio encoding device
Disclosed is an LPC residual signal encoding/decoding apparatus of an MDCT based unified voice and audio encoding device. The LPC residual signal encoding apparatus analyzes a property of an input signal, selects an encoding method of an LPC filtered signal, and encode the LPC residual signal based on one of a real filterbank, a complex filterbank, and an algebraic code excited linear prediction (ACELP).
1. A linear predicative coder (LPC) residual signal encoding apparatus of a modified discrete cosine transform (MDCT) based unified voice and audio encoding device, comprising:
a signal analyzing unit to analyze a property of an input signal and to select an encoding method for an LPC filtered signal;
a first encoding unit to encode the LPC residual signal based on a real filterbank according to the selection of the signal analyzing unit;
a second encoding unit to encode the LPC residual signal based on a complex filterbank according to the selection of the signal analyzing unit; and
a third encoding unit to encode the LPC residual signal based on an algebraic code excited linear prediction (ACELP) according to the selection of the signal analyzing unit,
wherein the first encoding unit or the second encoding unit encode the LPC residual signal when the input signal is an audio signal based on the selection of the signal analyzing unit, and
the third encoding unit encodes the LPC residual signal when the input signal is a voice signal.
2. The apparatus of claim 1 , wherein the first encoding unit performs an MDCT based filterbank with respect to the LPC residual signal, to encode the LPC residual signal.
3. The apparatus of claim 1 , wherein the second encoding unit performs a discrete Fourier transform (DFT) based filterbank with respect to the LPC residual signal, to encode the LPC residual signal.
4. The apparatus of claim 1 , wherein the second encoding unit performs a modified discrete sine transform (MDST) based filterbank with respect to the LPC residual signal, to encode the LPC residual signal.
5. The apparatus of claim 1 , wherein, when both a previous frame and a current frame are in an MDCT filterbank mode, the first encoding unit uses a window defined in Table 1 below,
TABLE 1
MDCT based
residual
MDCT based
A number of
filterbank
residual
coefficients
mode of a
filterbank
transformed
previous
mode of a
to a frequency
frame
current frame
domain
ZL
L
M
R
ZR
1, 2, 3
1
256
64
128
128
128
64
1, 2, 3
2
512
192
128
384
128
192
1, 2, 3
3
1024
448
128
896
128
448
wherein:
the ZL is a zero block section of a left side of a window;
the L is a section that is overlapped with a previous block;
the M is a section where a value of “1” is applicable;
the R is a section that is overlapped with a next block; and
the ZR is a zero block section of a left side of a window.
6. The apparatus of claim 1 , wherein, when both a previous frame and a current frame are in a complex filterbank mode, the second encoding unit uses a window defined in Table 2 below,
TABLE 2
MDCT based
MDCT based
A number of
residual
residual
coefficients
filterbank
filterbank
transformed to
mode of a
mode of a
a frequency
previous frame
current frame
domain
ZL
L
M
R
ZR
1
1
288
0
32
224
32
0
1
2
576
0
32
480
64
0
2
2
576
0
64
448
64
0
1
3
1152
0
32
992
128
0
2
3
1152
0
64
960
128
0
3
3
1152
0
128
896
128
0
7. The apparatus of claim 1 , wherein, when a previous frame is in an MDCT filterbank mode and a current frame is in a complex filterbank mode, the second encoding unit uses a window defined in Table 3,
TABLE 3
MDCT based
residual
MDCT based
A number of
filterbank
residual
coefficients
mode of a
filterbank
transformed
previous
mode of a
to a frequency
frame
current frame
domain
ZL
L
M
R
ZR
1, 2, 3
1
288
0
128
128
32
0
1, 2, 3
2
576
0
128
384
64
0
1, 2, 3
3
1152
0
128
896
128
0
8. The apparatus of claim 1 , wherein, when a previous frame is in a complex filterbank mode and a current frame is in an MDCT filterbank mode, the first encoding unit uses a window defined in Table 4 below,
TABLE 4
MDCT based
residual
MDCT based
A number of
filterbank
residual
coefficients
mode of a
filterbank
transformed
previous
mode of a
to a frequency
frame
current frame
domain
ZL
L
M
R
ZR
1, 2, 3
1
256
64
128
128
128
64
1, 2, 3
2
512
192
128
384
128
192
1, 2, 3
3
1024
448
128
896
128
448
9. The apparatus of claim 1 , wherein, when a previous frame performs encoding by using an ACELP and a current frame is in an MDCT filterbank, the first encoding unit uses a window defined in Table 5 below,
TABLE 5
MDCT based
A number of
residual
MDCT based
coefficients
filterbank
residual
transformed
mode of a
filterbank
to a
previous
mode of a
frequency
frame
current frame
domain
ZL
L
M
R
ZR
0
1
320
160
0
256
128
96
0
2
576
288
0
512
128
224
0
3
1152
512
128
1024
128
512
10. The apparatus of claim 1 , wherein the signal analyzing unit performs:
controlling the first encoding unit or the second encoding unit to perform encoding, when the input signal is an audio signal; and
controlling the third encoding unit to perform encoding, when the input signal is a voice signal.
11. An LPC residual signal encoding apparatus of an MDCT based unified voice and audio encoding device, comprising:
a signal analyzing unit to analyze a property of an input signal and to select an encoding method of an LPC filtered signal;
a first encoding unit to perform selectively one of a real filterbank based encoding and a complex filterbank based encoding, when the input signal is an audio signal; and
a second encoding unit to encode the LPC residual signal based on an ACELP, when the input signal is a voice signal.
12. The apparatus of claim 11 , wherein the signal analyzing unit generates a control command to selectively perform one of the real filterbank based encoding, the complex filterbank based encoding, and the ACELP based encoding.
13. The apparatus of claim 11 , wherein the first encoding unit comprises:
an MDCT encoding unit to perform an MDCT based encoding;
an MDST encoding unit to perform an MDST based encoding; and
an outputting unit to output at least one of an MDCT coefficient and an MDST coefficient according to the property of the input signal.
14. An LPC residual signal decoding apparatus of an MDCT based unified voice and audio decoding device, comprising:
a voice decoding unit to decode an LPC residual signal encoded from a frequency domain, when the encoded LPC residual signal is a voice signal;
an audio decoding unit to decode an LPC residual signal encoded from a time domain, when the encoded LPC residual signal is an audio signal; and
a distortion controlling unit to compensate for a distortion between an output signal of the audio decoding unit and an output signal of the voice decoding unit,
wherein the audio decoding unit comprises:
a first decoding unit to decode an LPC residual signal encoded based on a real filterbank; and
a second decoding unit to decode an LPC residual signal encoded based on a complex filterbank.
15. A processing method performed by one or more processors, comprising:
identifying a first block included in a previous frame;
identifying a second block included in a current frame;
generating an intentional signal related to the first block;
wherein the first block is processed by algebraic code excited linear prediction (ACELP), and the second block is processed by a modified discrete cosine transform (MDCT);
first overlap-adding the first block applied to a first window into the intentional signal applied to a second window; and
second overlap-adding the second block applied to a third window into the first overlapped result applied to the first window.
16. The processing method of claim 15 , wherein the first block and the second block have a 128 overlap size.