X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=libavcodec%2Flpc.c;h=315997cc154bca483a9a9e057d96d44a38e2d6c6;hb=59361d8c9d319098e3c96db2ac600030467212be;hp=07fc29265ac039a36f79c947d269f73a225c9ae2;hpb=d560c61125b3ee0ec8cd2e228f0604b63f85b8b2;p=ffmpeg

diff --git a/libavcodec/lpc.c b/libavcodec/lpc.c
index 07fc29265ac..315997cc154 100644
--- a/libavcodec/lpc.c
+++ b/libavcodec/lpc.c
@@ -167,6 +167,26 @@ int ff_lpc_calc_ref_coefs(LPCContext *s,
     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] = {0};
+    const double c = (len - 1)/2.0f;
+
+    /* Welch window */
+    for (i = 0; i < len; i++)
+        s->windowed_samples[i] = 1.0f - ((samples[i]-c)/c)*((samples[i]-c)/c);
+
+    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 signal/avg_err;
+}
+
 /**
  * Calculate LPC coefficients for multiple orders
  *