Add a function that can apply an order 2 rational transfer function in-place.

This function will be used in the upcoming AMR-NB floating point decoder for
high-pass filtering.

Patch by Colin McQuillan ( m.niloc googlemail com )

Originally committed as revision 19649 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 16 insertions, 0 deletions

diff --git a/libavcodec/acelp_filters.h b/libavcodec/acelp_filters.h
index b7f6a3abcb..2cbe9bb17d 100644
--- a/libavcodec/acelp_filters.h
+++ b/libavcodec/acelp_filters.h
@@ -81,4 +81,20 @@ void ff_acelp_interpolate(int16_t* out, const int16_t* in,
 void ff_acelp_high_pass_filter(int16_t* out, int hpf_f[2],
                                const int16_t* in, int length);
 
+/**
+ * Apply an order 2 rational transfer function in-place.
+ *
+ * @param samples [in/out]
+ * @param zero_coeffs z^-1 and z^-2 coefficients of the numerator
+ * @param pole_coeffs z^-1 and z^-2 coefficients of the denominator
+ * @param gain scale factor for final output
+ * @param mem intermediate values used by filter (should be 0 initially)
+ * @param n number of samples
+ */
+void ff_acelp_apply_order_2_transfer_function(float *samples,
+                                              const float zero_coeffs[2],
+                                              const float pole_coeffs[2],
+                                              float gain,
+                                              float mem[2], int n);
+
 #endif /* AVCODEC_ACELP_FILTERS_H */