Implement ff_decode_pitch_lag() that is used by both AMR and SIPR.

Based on code written by Colin McQuillan during his SoC project.

Originally committed as revision 20540 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 18 insertions, 0 deletions

diff --git a/libavcodec/acelp_pitch_delay.h b/libavcodec/acelp_pitch_delay.h
index 42307d2bba..2413145beb 100644
--- a/libavcodec/acelp_pitch_delay.h
+++ b/libavcodec/acelp_pitch_delay.h
@@ -234,4 +234,22 @@ float ff_amr_set_fixed_gain(float fixed_gain_factor, float fixed_mean_energy,
                             float *prediction_error, float energy_mean,
                             const float *pred_table);
 
+
+/**
+ * Decode the adaptive codebook index to the integer and fractional parts
+ * of the pitch lag for one subframe at 1/3 fractional precision.
+ *
+ * The choice of pitch lag is described in 3GPP TS 26.090 section 5.6.1.
+ *
+ * @param lag_int             integer part of pitch lag of the current subframe
+ * @param lag_frac            fractional part of pitch lag of the current subframe
+ * @param pitch_index         parsed adaptive codebook (pitch) index
+ * @param prev_lag_int        integer part of pitch lag for the previous subframe
+ * @param subframe            current subframe number
+ * @param third_as_first      treat the third frame the same way as the first
+ */
+void ff_decode_pitch_lag(int *lag_int, int *lag_frac, int pitch_index,
+                         const int prev_lag_int, const int subframe,
+                         int third_as_first, int resolution);
+
 #endif /* AVCODEC_ACELP_PITCH_DELAY_H */