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FFmpeg/libavcodec/lpc.c
Andreas Rheinhardt 790f793844 avutil/common: Don't auto-include mem.h 
There are lots of files that don't need it: The number of object
files that actually need it went down from 2011 to 884 here.

Keep it for external users in order to not cause breakages.

Also improve the other headers a bit while just at it.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
2024-03-31 00:08:43 +01:00

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/*
* 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/common.h"
#include "libavutil/lls.h"
#include "libavutil/mem.h"
#include "libavutil/mem_internal.h"
#define LPC_USE_DOUBLE
#include "lpc.h"
#include "lpc_functions.h"
#include "libavutil/avassert.h"
/**
* Schur recursion.
* Produces reflection coefficients from autocorrelation data.
*/
static inline void compute_ref_coefs(const LPC_TYPE *autoc, int max_order,
LPC_TYPE *ref, LPC_TYPE *error)
{
LPC_TYPE err;
LPC_TYPE gen0[MAX_LPC_ORDER], gen1[MAX_LPC_ORDER];
for (int i = 0; i < max_order; i++)
gen0[i] = gen1[i] = autoc[i + 1];
err = autoc[0];
ref[0] = -gen1[0] / ((LPC_USE_FIXED || err) ? err : 1);
err += gen1[0] * ref[0];
if (error)
error[0] = err;
for (int i = 1; i < max_order; i++) {
for (int j = 0; j < max_order - i; j++) {
gen1[j] = gen1[j + 1] + ref[i - 1] * gen0[j];
gen0[j] = gen1[j + 1] * ref[i - 1] + gen0[j];
}
ref[i] = -gen1[0] / ((LPC_USE_FIXED || err) ? err : 1);
err += gen1[0] * ref[i];
if (error)
error[i] = err;
}
}
/**
* Apply Welch window function to audio block
*/
static void lpc_apply_welch_window_c(const int32_t *data, ptrdiff_t len,
double *w_data)
{
int i, n2;
double w;
double c;
if (len == 1) {
w_data[0] = 0.0;
return;
}
n2 = (len >> 1);
c = 2.0 / (len - 1.0);
if (len & 1) {
for(i=0; i<n2; i++) {
w = c - i - 1.0;
w = 1.0 - (w * w);
w_data[i] = data[i] * w;
w_data[len-1-i] = data[len-1-i] * w;
}
w_data[n2] = 0.0;
return;
}
w_data+=n2;
data+=n2;
for(i=0; i<n2; i++) {
w = c - n2 + i;
w = 1.0 - (w * w);
w_data[-i-1] = data[-i-1] * w;
w_data[+i ] = data[+i ] * w;
}
}
/**
* Calculate autocorrelation data from audio samples
* A Welch window function is applied before calculation.
*/
static void lpc_compute_autocorr_c(const double *data, ptrdiff_t len, int lag,
double *autoc)
{
int i, j;
for(j=0; j<lag; j+=2){
double sum0 = 1.0, sum1 = 1.0;
for(i=j; i<len; i++){
sum0 += data[i] * data[i-j];
sum1 += data[i] * data[i-j-1];
}
autoc[j ] = sum0;
autoc[j+1] = sum1;
}
if(j==lag){
double sum = 1.0;
for(i=j-1; i<len; i+=2){
sum += data[i ] * data[i-j ]
+ data[i+1] * data[i-j+1];
}
autoc[j] = sum;
}
}
/**
* Quantize LPC coefficients
*/
static void quantize_lpc_coefs(double *lpc_in, int order, int precision,
int32_t *lpc_out, int *shift, int min_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 > min_shift)) {
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;
}
int ff_lpc_calc_ref_coefs(LPCContext *s,
const int32_t *samples, int order, double *ref)
{
double autoc[MAX_LPC_ORDER + 1];
s->lpc_apply_welch_window(samples, s->blocksize, s->windowed_samples);
s->lpc_compute_autocorr(s->windowed_samples, s->blocksize, order, autoc);
compute_ref_coefs(autoc, order, ref, NULL);
return order;
}
double ff_lpc_calc_ref_coefs_f(LPCContext *s, const float *samples, int len,
int order, double *ref)
{
int i;
double signal = 0.0f, avg_err = 0.0f;
double autoc[MAX_LPC_ORDER+1] = {0}, error[MAX_LPC_ORDER+1] = {0};
const double a = 0.5f, b = 1.0f - a;
/* Apply windowing */
for (i = 0; i <= len / 2; i++) {
double weight = a - b*cos((2*M_PI*i)/(len - 1));
s->windowed_samples[i] = weight*samples[i];
s->windowed_samples[len-1-i] = weight*samples[len-1-i];
}
s->lpc_compute_autocorr(s->windowed_samples, len, order, autoc);
signal = autoc[0];
compute_ref_coefs(autoc, order, ref, error);
for (i = 0; i < order; i++)
avg_err = (avg_err + error[i])/2.0f;
return avg_err ? signal/avg_err : NAN;
}
/**
* Calculate LPC coefficients for multiple orders
*
* @param lpc_type LPC method for determining coefficients,
* see #FFLPCType for details
*/
int ff_lpc_calc_coefs(LPCContext *s,
const int32_t *samples, int blocksize, int min_order,
int max_order, int precision,
int32_t coefs[][MAX_LPC_ORDER], int *shift,
enum FFLPCType lpc_type, int lpc_passes,
int omethod, int min_shift, int max_shift, int zero_shift)
{
double autoc[MAX_LPC_ORDER+1];
double ref[MAX_LPC_ORDER] = { 0 };
double lpc[MAX_LPC_ORDER][MAX_LPC_ORDER];
int i, j, pass = 0;
int opt_order;
av_assert2(max_order >= MIN_LPC_ORDER && max_order <= MAX_LPC_ORDER &&
lpc_type > FF_LPC_TYPE_FIXED);
av_assert0(lpc_type == FF_LPC_TYPE_CHOLESKY || lpc_type == FF_LPC_TYPE_LEVINSON);
/* reinit LPC context if parameters have changed */
if (blocksize != s->blocksize || max_order != s->max_order ||
lpc_type != s->lpc_type) {
ff_lpc_end(s);
ff_lpc_init(s, blocksize, max_order, lpc_type);
}
if(lpc_passes <= 0)
lpc_passes = 2;
if (lpc_type == FF_LPC_TYPE_LEVINSON || (lpc_type == FF_LPC_TYPE_CHOLESKY && lpc_passes > 1)) {
s->lpc_apply_welch_window(samples, blocksize, s->windowed_samples);
s->lpc_compute_autocorr(s->windowed_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]);
pass++;
}
if (lpc_type == FF_LPC_TYPE_CHOLESKY) {
LLSModel *m = s->lls_models;
LOCAL_ALIGNED(32, double, var, [FFALIGN(MAX_LPC_ORDER+1,4)]);
double av_uninit(weight);
memset(var, 0, FFALIGN(MAX_LPC_ORDER+1,4)*sizeof(*var));
for(j=0; j<max_order; j++)
m[0].coeff[max_order-1][j] = -lpc[max_order-1][j];
for(; pass<lpc_passes; pass++){
avpriv_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= m[pass&1].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++;
m[pass&1].update_lls(&m[pass&1], var);
}
avpriv_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],
min_shift, 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],
min_shift, max_shift, zero_shift);
}
}
return opt_order;
}
av_cold int ff_lpc_init(LPCContext *s, int blocksize, int max_order,
enum FFLPCType lpc_type)
{
s->blocksize = blocksize;
s->max_order = max_order;
s->lpc_type = lpc_type;
s->windowed_buffer = av_mallocz((blocksize + 2 + FFALIGN(max_order, 4)) *
sizeof(*s->windowed_samples));
if (!s->windowed_buffer)
return AVERROR(ENOMEM);
s->windowed_samples = s->windowed_buffer + FFALIGN(max_order, 4);
s->lpc_apply_welch_window = lpc_apply_welch_window_c;
s->lpc_compute_autocorr = lpc_compute_autocorr_c;
#if ARCH_RISCV
ff_lpc_init_riscv(s);
#elif ARCH_X86
ff_lpc_init_x86(s);
#endif
return 0;
}
av_cold void ff_lpc_end(LPCContext *s)
{
av_freep(&s->windowed_buffer);
}
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