mirror of
https://git.ffmpeg.org/ffmpeg.git
synced 2024-12-24 16:22:37 +00:00
3cfe88194a
uninitialized. Patch by Patrik Kullman (patrik A yes D nu). Originally committed as revision 17218 to svn://svn.ffmpeg.org/ffmpeg/trunk
175 lines
5.3 KiB
C
175 lines
5.3 KiB
C
/**
|
|
* LPC utility code
|
|
* 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
|
|
*/
|
|
|
|
#include "libavutil/lls.h"
|
|
#include "dsputil.h"
|
|
|
|
#define LPC_USE_DOUBLE
|
|
#include "lpc.h"
|
|
|
|
|
|
/**
|
|
* Quantize LPC coefficients
|
|
*/
|
|
static void quantize_lpc_coefs(double *lpc_in, int order, int precision,
|
|
int32_t *lpc_out, int *shift, int max_shift, int zero_shift)
|
|
{
|
|
int i;
|
|
double cmax, error;
|
|
int32_t qmax;
|
|
int sh;
|
|
|
|
/* define maximum levels */
|
|
qmax = (1 << (precision - 1)) - 1;
|
|
|
|
/* find maximum coefficient value */
|
|
cmax = 0.0;
|
|
for(i=0; i<order; i++) {
|
|
cmax= FFMAX(cmax, fabs(lpc_in[i]));
|
|
}
|
|
|
|
/* if maximum value quantizes to zero, return all zeros */
|
|
if(cmax * (1 << max_shift) < 1.0) {
|
|
*shift = zero_shift;
|
|
memset(lpc_out, 0, sizeof(int32_t) * order);
|
|
return;
|
|
}
|
|
|
|
/* calculate level shift which scales max coeff to available bits */
|
|
sh = max_shift;
|
|
while((cmax * (1 << sh) > qmax) && (sh > 0)) {
|
|
sh--;
|
|
}
|
|
|
|
/* since negative shift values are unsupported in decoder, scale down
|
|
coefficients instead */
|
|
if(sh == 0 && cmax > qmax) {
|
|
double scale = ((double)qmax) / cmax;
|
|
for(i=0; i<order; i++) {
|
|
lpc_in[i] *= scale;
|
|
}
|
|
}
|
|
|
|
/* output quantized coefficients and level shift */
|
|
error=0;
|
|
for(i=0; i<order; i++) {
|
|
error -= lpc_in[i] * (1 << sh);
|
|
lpc_out[i] = av_clip(lrintf(error), -qmax, qmax);
|
|
error -= lpc_out[i];
|
|
}
|
|
*shift = sh;
|
|
}
|
|
|
|
static int estimate_best_order(double *ref, int min_order, int max_order)
|
|
{
|
|
int i, est;
|
|
|
|
est = min_order;
|
|
for(i=max_order-1; i>=min_order-1; i--) {
|
|
if(ref[i] > 0.10) {
|
|
est = i+1;
|
|
break;
|
|
}
|
|
}
|
|
return est;
|
|
}
|
|
|
|
/**
|
|
* Calculate LPC coefficients for multiple orders
|
|
*
|
|
* @param use_lpc LPC method for determining coefficients
|
|
* 0 = LPC with fixed pre-defined coeffs
|
|
* 1 = LPC with coeffs determined by Levinson-Durbin recursion
|
|
* 2+ = LPC with coeffs determined by Cholesky factorization using (use_lpc-1) passes.
|
|
*/
|
|
int ff_lpc_calc_coefs(DSPContext *s,
|
|
const int32_t *samples, int blocksize, int min_order,
|
|
int max_order, int precision,
|
|
int32_t coefs[][MAX_LPC_ORDER], int *shift, int use_lpc,
|
|
int omethod, int max_shift, int zero_shift)
|
|
{
|
|
double autoc[MAX_LPC_ORDER+1];
|
|
double ref[MAX_LPC_ORDER];
|
|
double lpc[MAX_LPC_ORDER][MAX_LPC_ORDER];
|
|
int i, j, pass;
|
|
int opt_order;
|
|
|
|
assert(max_order >= MIN_LPC_ORDER && max_order <= MAX_LPC_ORDER && use_lpc > 0);
|
|
|
|
if(use_lpc == 1){
|
|
s->flac_compute_autocorr(samples, blocksize, max_order, autoc);
|
|
|
|
compute_lpc_coefs(autoc, max_order, &lpc[0][0], MAX_LPC_ORDER, 0, 1);
|
|
|
|
for(i=0; i<max_order; i++)
|
|
ref[i] = fabs(lpc[i][i]);
|
|
}else{
|
|
LLSModel m[2];
|
|
double var[MAX_LPC_ORDER+1], av_uninit(weight);
|
|
|
|
for(pass=0; pass<use_lpc-1; pass++){
|
|
av_init_lls(&m[pass&1], max_order);
|
|
|
|
weight=0;
|
|
for(i=max_order; i<blocksize; i++){
|
|
for(j=0; j<=max_order; j++)
|
|
var[j]= samples[i-j];
|
|
|
|
if(pass){
|
|
double eval, inv, rinv;
|
|
eval= av_evaluate_lls(&m[(pass-1)&1], var+1, max_order-1);
|
|
eval= (512>>pass) + fabs(eval - var[0]);
|
|
inv = 1/eval;
|
|
rinv = sqrt(inv);
|
|
for(j=0; j<=max_order; j++)
|
|
var[j] *= rinv;
|
|
weight += inv;
|
|
}else
|
|
weight++;
|
|
|
|
av_update_lls(&m[pass&1], var, 1.0);
|
|
}
|
|
av_solve_lls(&m[pass&1], 0.001, 0);
|
|
}
|
|
|
|
for(i=0; i<max_order; i++){
|
|
for(j=0; j<max_order; j++)
|
|
lpc[i][j]=-m[(pass-1)&1].coeff[i][j];
|
|
ref[i]= sqrt(m[(pass-1)&1].variance[i] / weight) * (blocksize - max_order) / 4000;
|
|
}
|
|
for(i=max_order-1; i>0; i--)
|
|
ref[i] = ref[i-1] - ref[i];
|
|
}
|
|
opt_order = max_order;
|
|
|
|
if(omethod == ORDER_METHOD_EST) {
|
|
opt_order = estimate_best_order(ref, min_order, max_order);
|
|
i = opt_order-1;
|
|
quantize_lpc_coefs(lpc[i], i+1, precision, coefs[i], &shift[i], max_shift, zero_shift);
|
|
} else {
|
|
for(i=min_order-1; i<max_order; i++) {
|
|
quantize_lpc_coefs(lpc[i], i+1, precision, coefs[i], &shift[i], max_shift, zero_shift);
|
|
}
|
|
}
|
|
|
|
return opt_order;
|
|
}
|