[FFmpeg-cvslog] r20421 - in trunk/libavcodec: acelp_pitch_delay.c acelp_pitch_delay.h
vitor
subversion
Sat Oct 31 03:02:30 CET 2009
Author: vitor
Date: Sat Oct 31 03:02:30 2009
New Revision: 20421
Log:
Implement AMR gain function that is used by both AMR and SIPR.
Based on AMR SoC code by Robert Swain and Colin McQuillan.
Modified:
trunk/libavcodec/acelp_pitch_delay.c
trunk/libavcodec/acelp_pitch_delay.h
Modified: trunk/libavcodec/acelp_pitch_delay.c
==============================================================================
--- trunk/libavcodec/acelp_pitch_delay.c Fri Oct 30 19:17:16 2009 (r20420)
+++ trunk/libavcodec/acelp_pitch_delay.c Sat Oct 31 03:02:30 2009 (r20421)
@@ -119,3 +119,24 @@ int16_t ff_acelp_decode_gain_code(
return mr_energy >> 12;
#endif
}
+
+float ff_amr_set_fixed_gain(float fixed_gain_factor, float fixed_mean_energy,
+ float *prediction_error, float energy_mean,
+ const float *pred_table)
+{
+ // Equations 66-69:
+ // ^g_c = ^gamma_gc * 100.05 (predicted dB + mean dB - dB of fixed vector)
+ // Note 10^(0.05 * -10log(average x2)) = 1/sqrt((average x2)).
+ float val = fixed_gain_factor *
+ exp2f(log2f(10.0) * 0.05 *
+ (ff_dot_productf(pred_table, prediction_error, 4) +
+ energy_mean)) /
+ sqrtf(fixed_mean_energy);
+
+ // update quantified prediction error energy history
+ memmove(&prediction_error[0], &prediction_error[1],
+ 3 * sizeof(prediction_error[0]));
+ prediction_error[3] = 20.0 * log10f(fixed_gain_factor);
+
+ return val;
+}
Modified: trunk/libavcodec/acelp_pitch_delay.h
==============================================================================
--- trunk/libavcodec/acelp_pitch_delay.h Fri Oct 30 19:17:16 2009 (r20420)
+++ trunk/libavcodec/acelp_pitch_delay.h Sat Oct 31 03:02:30 2009 (r20421)
@@ -220,4 +220,18 @@ int16_t ff_acelp_decode_gain_code(
int subframe_size,
int max_pred_order);
+/**
+ * Calculate fixed gain (part of section 6.1.3 of AMR spec)
+ *
+ * @param fixed_gain_factor gain correction factor
+ * @param fixed_energy decoded algebraic codebook vector energy
+ * @param prediction_error vector of the quantified predictor errors of
+ * the four previous subframes. It is updated by this function.
+ * @param energy_mean desired mean innovation energy
+ * @param pred_table table of four moving average coefficients
+ */
+float ff_amr_set_fixed_gain(float fixed_gain_factor, float fixed_mean_energy,
+ float *prediction_error, float energy_mean,
+ const float *pred_table);
+
#endif /* AVCODEC_ACELP_PITCH_DELAY_H */
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