FFmpeg
libavcodec
lpc_functions.h
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/*
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* LPC utility functions
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* Copyright (c) 2006 Justin Ruggles <justin.ruggles@gmail.com>
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#ifndef AVCODEC_LPC_FUNCTIONS_H
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#define AVCODEC_LPC_FUNCTIONS_H
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#include "
libavutil/avassert.h
"
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#ifndef LPC_USE_FIXED
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#define LPC_USE_FIXED 0
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#endif
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#if LPC_USE_FIXED
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typedef
int
LPC_TYPE
;
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typedef
unsigned
LPC_TYPE_U
;
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#else
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#ifndef LPC_SRA_R
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#define LPC_SRA_R(x, y) (x)
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#define LPC_MUL26(x, y) ((x) * (y))
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#define LPC_FIXR(x) ((float)(x))
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#endif
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#ifdef LPC_USE_DOUBLE
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typedef
double
LPC_TYPE
;
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typedef
double
LPC_TYPE_U
;
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#else
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typedef
float
LPC_TYPE
;
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typedef
float
LPC_TYPE_U
;
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#endif
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#endif // USE_FIXED
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/**
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* Levinson-Durbin recursion.
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* Produce LPC coefficients from autocorrelation data.
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*/
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static
inline
int
compute_lpc_coefs
(
const
LPC_TYPE
*autoc,
int
max_order,
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LPC_TYPE
*lpc,
int
lpc_stride,
int
fail
,
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int
normalize
)
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{
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LPC_TYPE
err = 0;
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LPC_TYPE
*lpc_last = lpc;
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av_assert2
(
normalize
|| !
fail
);
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if
(
normalize
)
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err = *autoc++;
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if
(
fail
&& (autoc[max_order - 1] == 0 || err <= 0))
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return
-1;
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for
(
int
i
= 0;
i
< max_order;
i
++) {
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LPC_TYPE
r
=
LPC_SRA_R
(-autoc[
i
], 5);
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if
(
normalize
) {
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for
(
int
j = 0; j <
i
; j++)
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r
-= lpc_last[j] * autoc[
i
-j-1];
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if
(err)
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r
/= err;
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err *=
LPC_FIXR
(1.0) - (
r
*
r
);
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}
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lpc[
i
] =
r
;
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for
(
int
j = 0; j < (
i
+ 1) >> 1; j++) {
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LPC_TYPE
f
= lpc_last[ j];
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LPC_TYPE
b
= lpc_last[
i
-1-j];
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lpc[ j] =
f
+ (
LPC_TYPE_U
)
LPC_MUL26
(
r
,
b
);
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lpc[
i
-1-j] =
b
+ (
LPC_TYPE_U
)
LPC_MUL26
(
r
,
f
);
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}
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if
(
fail
&& err < 0)
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return
-1;
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lpc_last = lpc;
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lpc += lpc_stride;
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}
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return
0;
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}
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#endif
/* AVCODEC_LPC_FUNCTIONS_H */
r
const char * r
Definition:
vf_curves.c:127
b
#define b
Definition:
input.c:41
fail
#define fail()
Definition:
checkasm.h:188
avassert.h
LPC_MUL26
#define LPC_MUL26(x, y)
Definition:
lpc_functions.h:37
compute_lpc_coefs
static int compute_lpc_coefs(const LPC_TYPE *autoc, int max_order, LPC_TYPE *lpc, int lpc_stride, int fail, int normalize)
Levinson-Durbin recursion.
Definition:
lpc_functions.h:54
f
f
Definition:
af_crystalizer.c:122
normalize
Definition:
normalize.py:1
av_assert2
#define av_assert2(cond)
assert() equivalent, that does lie in speed critical code.
Definition:
avassert.h:67
i
#define i(width, name, range_min, range_max)
Definition:
cbs_h2645.c:256
LPC_TYPE_U
float LPC_TYPE_U
Definition:
lpc_functions.h:46
LPC_TYPE
float LPC_TYPE
Definition:
lpc_functions.h:45
LPC_FIXR
#define LPC_FIXR(x)
Definition:
lpc_functions.h:38
LPC_SRA_R
#define LPC_SRA_R(x, y)
Definition:
lpc_functions.h:36
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