lavc: G.723.1 encoder

Additional improvements by Michael Niedermayer <michaelni@gmx.at>.

Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>

libavcodec/celp_math.h

@@ -42,6 +42,16 @@ int ff_exp2(uint16_t power);
  */
 int ff_log2_q15(uint32_t value);
 
+/**
+ * Calculate the dot product of 2 int16_t vectors.
+ * @param a input data array
+ * @param b input data array
+ * @param length number of elements
+ *
+ * @return dot product = sum of elementwise products
+ */
+int64_t ff_dot_product(const int16_t *a, const int16_t *b, int length);
+
 /**
  * Shift value left or right depending on sign of offset parameter.
  * @param value value to shift