X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=libavcodec%2Flpc.c;h=1482e57615692fc931923ab4fc11e5d6da2a9467;hb=cfdaa4de6c496b0b761c763cd18067cb1af268a7;hp=792abe4d1cc456792f3e1a5ef483cbf34d3d8a07;hpb=56c07e298914d0533a74bb4ba4be4abc8ea6b245;p=ffmpeg

diff --git a/libavcodec/lpc.c b/libavcodec/lpc.c
index 792abe4d1cc..1482e576156 100644
--- a/libavcodec/lpc.c
+++ b/libavcodec/lpc.c
@@ -1,68 +1,85 @@
-/**
+/*
  * LPC utility code
- * Copyright (c) 2006  Justin Ruggles <jruggle@earthlink.net>
+ * 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 r, err, tmp;
-   double lpc_tmp[MAX_LPC_ORDER];
-
-   for(i=0; i<max_order; i++) lpc_tmp[i] = 0;
-   err = autoc[0];
-
-   for(i=0; i<max_order; i++) {
-      r = -autoc[i+1];
-      for(j=0; j<i; j++) {
-          r -= lpc_tmp[j] * autoc[i-j];
-      }
-      r /= err;
-      ref[i] = fabs(r);
-
-      err *= 1.0 - (r * r);
-
-      i2 = (i >> 1);
-      lpc_tmp[i] = r;
-      for(j=0; j<i2; j++) {
-         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;
-      }
-
-      for(j=0; j<=i; j++) {
-          lpc[i][j] = -lpc_tmp[j];
-      }
-   }
+    int i, n2;
+    double w;
+    double c;
+
+    /* The optimization in commit fa4ed8c does not support odd len.
+     * If someone wants odd len extend that change. */
+    assert(!(len & 1));
+
+    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;
+    }
+
+    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;
+    }
 }
 
 /**
@@ -110,19 +127,19 @@ static void quantize_lpc_coefs(double *lpc_in, int order, int precision,
     /* 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];
     }
     *shift = sh;
 }
 
-static int estimate_best_order(double *ref, int max_order)
+static int estimate_best_order(double *ref, int min_order, int max_order)
 {
     int i, est;
 
-    est = 1;
-    for(i=max_order-1; i>=0; i--) {
+    est = min_order;
+    for(i=max_order-1; i>=min_order-1; i--) {
         if(ref[i] > 0.10) {
             est = i+1;
             break;
@@ -131,32 +148,71 @@ static int estimate_best_order(double *ref, int max_order)
     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,
-                      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)
+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 max_shift, int zero_shift)
 {
     double autoc[MAX_LPC_ORDER+1];
-    double ref[MAX_LPC_ORDER];
+    double ref[MAX_LPC_ORDER] = { 0 };
     double lpc[MAX_LPC_ORDER][MAX_LPC_ORDER];
-    int i, j, pass;
+    int i, j, pass = 0;
     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 || (lpc_type == FF_LPC_TYPE_CHOLESKY && lpc_passes > 1)) {
+        s->lpc_apply_welch_window(samples, blocksize, s->windowed_samples);
 
-    if(use_lpc == 1){
-        s->flac_compute_autocorr(samples, blocksize, max_order, autoc);
+        s->lpc_compute_autocorr(s->windowed_samples, blocksize, max_order, autoc);
 
-        compute_lpc_coefs(autoc, max_order, lpc, ref);
-    }else{
+        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[2];
-        double var[MAX_LPC_ORDER+1], weight;
+        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=0; pass<use_lpc-1; pass++){
-            av_init_lls(&m[pass&1], max_order);
+        for(; pass<lpc_passes; pass++){
+            avpriv_init_lls(&m[pass&1], max_order);
 
             weight=0;
             for(i=max_order; i<blocksize; i++){
@@ -165,7 +221,7 @@ int ff_lpc_calc_coefs(DSPContext *s,
 
                 if(pass){
                     double eval, inv, rinv;
-                    eval= av_evaluate_lls(&m[(pass-1)&1], var+1, max_order-1);
+                    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);
@@ -175,14 +231,14 @@ int ff_lpc_calc_coefs(DSPContext *s,
                 }else
                     weight++;
 
-                av_update_lls(&m[pass&1], var, 1.0);
+                m[pass&1].update_lls(&m[pass&1], var);
             }
-            av_solve_lls(&m[pass&1], 0.001, 0);
+            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];
+                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--)
@@ -191,7 +247,7 @@ int ff_lpc_calc_coefs(DSPContext *s,
     opt_order = max_order;
 
     if(omethod == ORDER_METHOD_EST) {
-        opt_order = estimate_best_order(ref, max_order);
+        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 {
@@ -202,3 +258,30 @@ int ff_lpc_calc_coefs(DSPContext *s,
 
     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_X86)
+        ff_lpc_init_x86(s);
+
+    return 0;
+}
+
+av_cold void ff_lpc_end(LPCContext *s)
+{
+    av_freep(&s->windowed_buffer);
+}