Implement ff_scale_vector_to_given_sum_of_squares()

to aid generic gain control routines. Changes
for qcelp are included. Patch Collin McQuillan.

Originally committed as revision 20450 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 12 insertions, 0 deletions

diff --git a/libavcodec/acelp_vectors.c b/libavcodec/acelp_vectors.c
index 2d9aa1ad79..e6979205b9 100644
--- a/libavcodec/acelp_vectors.c
+++ b/libavcodec/acelp_vectors.c
@@ -22,6 +22,7 @@
 
 #include <inttypes.h>
 #include "avcodec.h"
+#include "celp_math.h"
 #include "acelp_vectors.h"
 #include "celp_math.h"
 
@@ -177,3 +178,14 @@ void ff_adaptative_gain_control(float *buf_out, float speech_energ,
 
     *gain_mem = mem;
 }
+
+void ff_scale_vector_to_given_sum_of_squares(float *out, const float *in,
+                                             float sum_of_squares, const int n)
+{
+    int i;
+    float scalefactor = ff_dot_productf(in, in, n);
+    if (scalefactor)
+        scalefactor = sqrt(sum_of_squares / scalefactor);
+    for (i = 0; i < n; i++)
+        out[i] = in[i] * scalefactor;
+}