mirror of
https://github.com/FFmpeg/FFmpeg.git
synced 2024-12-12 19:18:44 +02:00
aaf26cffba
And move compute_ref_coefs() to its only user: lpc.c There is no overlap between the users of compute_lpc_coefs() and lpc proper. Reviewed-by: Lynne <dev@lynne.ee> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
101 lines
2.6 KiB
C
101 lines
2.6 KiB
C
/*
|
|
* LPC utility functions
|
|
* Copyright (c) 2006 Justin Ruggles <justin.ruggles@gmail.com>
|
|
*
|
|
* This file is part of FFmpeg.
|
|
*
|
|
* FFmpeg is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU Lesser General Public
|
|
* License as published by the Free Software Foundation; either
|
|
* version 2.1 of the License, or (at your option) any later version.
|
|
*
|
|
* FFmpeg is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
* Lesser General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU Lesser General Public
|
|
* License along with FFmpeg; if not, write to the Free Software
|
|
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
|
|
*/
|
|
|
|
#ifndef AVCODEC_LPC_FUNCTIONS_H
|
|
#define AVCODEC_LPC_FUNCTIONS_H
|
|
|
|
#include "libavutil/avassert.h"
|
|
|
|
#ifndef LPC_USE_FIXED
|
|
#define LPC_USE_FIXED 0
|
|
#endif
|
|
|
|
#if LPC_USE_FIXED
|
|
typedef int LPC_TYPE;
|
|
typedef unsigned LPC_TYPE_U;
|
|
#else
|
|
#ifndef LPC_SRA_R
|
|
#define LPC_SRA_R(x, y) (x)
|
|
#define LPC_MUL26(x, y) ((x) * (y))
|
|
#define LPC_FIXR(x) ((float)(x))
|
|
#endif
|
|
|
|
#ifdef LPC_USE_DOUBLE
|
|
typedef double LPC_TYPE;
|
|
typedef double LPC_TYPE_U;
|
|
#else
|
|
typedef float LPC_TYPE;
|
|
typedef float LPC_TYPE_U;
|
|
#endif
|
|
#endif // USE_FIXED
|
|
|
|
/**
|
|
* Levinson-Durbin recursion.
|
|
* Produce LPC coefficients from autocorrelation data.
|
|
*/
|
|
static inline int compute_lpc_coefs(const LPC_TYPE *autoc, int max_order,
|
|
LPC_TYPE *lpc, int lpc_stride, int fail,
|
|
int normalize)
|
|
{
|
|
LPC_TYPE err = 0;
|
|
LPC_TYPE *lpc_last = lpc;
|
|
|
|
av_assert2(normalize || !fail);
|
|
|
|
if (normalize)
|
|
err = *autoc++;
|
|
|
|
if (fail && (autoc[max_order - 1] == 0 || err <= 0))
|
|
return -1;
|
|
|
|
for(int i = 0; i < max_order; i++) {
|
|
LPC_TYPE r = LPC_SRA_R(-autoc[i], 5);
|
|
|
|
if (normalize) {
|
|
for(int j = 0; j < i; j++)
|
|
r -= lpc_last[j] * autoc[i-j-1];
|
|
|
|
if (err)
|
|
r /= err;
|
|
err *= LPC_FIXR(1.0) - (r * r);
|
|
}
|
|
|
|
lpc[i] = r;
|
|
|
|
for(int j = 0; j < (i + 1) >> 1; j++) {
|
|
LPC_TYPE f = lpc_last[ j];
|
|
LPC_TYPE b = lpc_last[i-1-j];
|
|
lpc[ j] = f + (LPC_TYPE_U)LPC_MUL26(r, b);
|
|
lpc[i-1-j] = b + (LPC_TYPE_U)LPC_MUL26(r, f);
|
|
}
|
|
|
|
if (fail && err < 0)
|
|
return -1;
|
|
|
|
lpc_last = lpc;
|
|
lpc += lpc_stride;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
#endif /* AVCODEC_LPC_FUNCTIONS_H */
|