X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=libavcodec%2Flpc.c;h=58bb02de7fce72659a402460476ab071aa83274b;hb=d1be646e906487b395190af1d6dd8d33c22bf25f;hp=8c21a2c4e532e3adc216c5a94ce1e2b331814de0;hpb=9045f5e72d6916bd93e0a9b26a8e4a2598fee6f1;p=ffmpeg

diff --git a/libavcodec/lpc.c b/libavcodec/lpc.c
index 8c21a2c4e53..58bb02de7fc 100644
--- a/libavcodec/lpc.c
+++ b/libavcodec/lpc.c
@@ -1,68 +1,83 @@
 /**
  * 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/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;
+
+    assert(!(len&1)); //the optimization in r11881 does not support odd len
+                      //if someone wants odd len extend the change in r11881
+
+    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 +125,19 @@ 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;
@@ -133,11 +148,17 @@ static int estimate_best_order(double *ref, int max_order)
 
 /**
  * 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,
+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 AVLPCType lpc_type, int lpc_passes,
                       int omethod, int max_shift, int zero_shift)
 {
     double autoc[MAX_LPC_ORDER+1];
@@ -146,17 +167,32 @@ int ff_lpc_calc_coefs(DSPContext *s,
     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 > AV_LPC_TYPE_FIXED);
 
-    if(use_lpc == 1){
-        s->flac_compute_autocorr(samples, blocksize, max_order, autoc);
+    /* 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 == AV_LPC_TYPE_LEVINSON) {
+        double *windowed_samples = s->windowed_samples + max_order;
+
+        s->lpc_apply_welch_window(samples, blocksize, windowed_samples);
+
+        s->lpc_compute_autocorr(windowed_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 == AV_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;
@@ -183,7 +219,7 @@ int ff_lpc_calc_coefs(DSPContext *s,
 
         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--)
@@ -192,7 +228,7 @@ 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 {
@@ -203,3 +239,33 @@ int ff_lpc_calc_coefs(DSPContext *s,
 
     return opt_order;
 }
+
+av_cold int ff_lpc_init(LPCContext *s, int blocksize, int max_order,
+                        enum AVLPCType lpc_type)
+{
+    s->blocksize = blocksize;
+    s->max_order = max_order;
+    s->lpc_type  = lpc_type;
+
+    if (lpc_type == AV_LPC_TYPE_LEVINSON) {
+        s->windowed_samples = av_mallocz((blocksize + max_order + 2) *
+                                         sizeof(*s->windowed_samples));
+        if (!s->windowed_samples)
+            return AVERROR(ENOMEM);
+    } else {
+        s->windowed_samples = NULL;
+    }
+
+    s->lpc_apply_welch_window = lpc_apply_welch_window_c;
+    s->lpc_compute_autocorr   = lpc_compute_autocorr_c;
+
+    if (HAVE_MMX)
+        ff_lpc_init_x86(s);
+
+    return 0;
+}
+
+av_cold void ff_lpc_end(LPCContext *s)
+{
+    av_freep(&s->windowed_samples);
+}