-/**
+/*
* LPC utility code
* Copyright (c) 2006 Justin Ruggles <justin.ruggles@gmail.com>
*
- * This file is part of FFmpeg.
+ * This file is part of Libav.
*
- * FFmpeg is free software; you can redistribute it and/or
+ * Libav 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,
+ * Libav 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
+ * License along with Libav; 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 "dsputil.h"
+
+#define LPC_USE_DOUBLE
#include "lpc.h"
/**
- * Levinson-Durbin recursion.
- * Produces LPC coefficients from autocorrelation data.
+ * Apply Welch window function to audio block
*/
-static void compute_lpc_coefs(const double *autoc, int max_order,
- double lpc[][MAX_LPC_ORDER], double *ref)
+static void lpc_apply_welch_window_c(const int32_t *data, int len,
+ double *w_data)
{
- int i, j, i2;
- double err = autoc[0];
- double lpc_tmp[MAX_LPC_ORDER];
-
- for(i=0; i<max_order; i++) {
- double r = -autoc[i+1];
- for(j=0; j<i; j++) {
- r -= lpc_tmp[j] * autoc[i-j];
- }
- r /= err;
- ref[i] = fabs(r);
+ int i, n2;
+ double w;
+ double c;
- err *= 1.0 - (r * r);
+ /* The optimization in commit fa4ed8c does not support odd len.
+ * If someone wants odd len extend that change. */
+ assert(!(len & 1));
- i2 = (i >> 1);
- lpc_tmp[i] = r;
- for(j=0; j<i2; j++) {
- double tmp = lpc_tmp[j];
- lpc_tmp[j] += r * lpc_tmp[i-1-j];
- lpc_tmp[i-1-j] += r * tmp;
- }
- if(i & 1) {
- lpc_tmp[j] += lpc_tmp[j] * r;
+ n2 = (len >> 1);
+ c = 2.0 / (len - 1.0);
+
+ 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, int 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;
+ }
- for(j=0; j<=i; j++) {
- lpc[i][j] = -lpc_tmp[j];
+ 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;
}
}
/* output quantized coefficients and level shift */
error=0;
for(i=0; i<order; i++) {
- error += lpc_in[i] * (1 << sh);
+ error -= lpc_in[i] * (1 << sh);
lpc_out[i] = av_clip(lrintf(error), -qmax, qmax);
error -= lpc_out[i];
}
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;
+}
+
/**
* Calculate LPC coefficients for multiple orders
+ *
+ * @param lpc_type LPC method for determining coefficients,
+ * see #FFLPCType for details
*/
-int ff_lpc_calc_coefs(DSPContext *s,
+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, int use_lpc,
+ int32_t coefs[][MAX_LPC_ORDER], int *shift,
+ enum FFLPCType lpc_type, int lpc_passes,
int omethod, int max_shift, int zero_shift)
{
double autoc[MAX_LPC_ORDER+1];
int i, j, pass;
int opt_order;
- assert(max_order >= MIN_LPC_ORDER && max_order <= MAX_LPC_ORDER);
+ assert(max_order >= MIN_LPC_ORDER && max_order <= MAX_LPC_ORDER &&
+ lpc_type > FF_LPC_TYPE_FIXED);
+
+ /* 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_type == FF_LPC_TYPE_LEVINSON) {
+ s->lpc_apply_welch_window(samples, blocksize, s->windowed_samples);
+
+ s->lpc_compute_autocorr(s->windowed_samples, blocksize, max_order, autoc);
- 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);
- compute_lpc_coefs(autoc, max_order, lpc, ref);
- }else{
+ for(i=0; i<max_order; i++)
+ ref[i] = fabs(lpc[i][i]);
+ } else if (lpc_type == FF_LPC_TYPE_CHOLESKY) {
LLSModel m[2];
- double var[MAX_LPC_ORDER+1], weight;
+ double var[MAX_LPC_ORDER+1], av_uninit(weight);
- for(pass=0; pass<use_lpc-1; pass++){
+ for(pass=0; pass<lpc_passes; pass++){
av_init_lls(&m[pass&1], max_order);
weight=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];
+ 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--)
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;
+
+ if (lpc_type == FF_LPC_TYPE_LEVINSON) {
+ 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);
+ } else {
+ s->windowed_samples = NULL;
+ }
+
+ s->lpc_apply_welch_window = lpc_apply_welch_window_c;
+ s->lpc_compute_autocorr = lpc_compute_autocorr_c;
+
+ if (ARCH_X86)
+ ff_lpc_init_x86(s);
+
+ return 0;
+}
+
+av_cold void ff_lpc_end(LPCContext *s)
+{
+ av_freep(&s->windowed_buffer);
+}
projects / ffmpeg / blobdiff