diff options
author | Vitor Sessak <vitor1001@gmail.com> | 2009-10-31 05:02:30 +0300 |
---|---|---|
committer | Vitor Sessak <vitor1001@gmail.com> | 2009-10-31 05:02:30 +0300 |
commit | 083c5a48ece9a6f316c49f383fa056279c811fd6 (patch) | |
tree | 2b357924276a95ef6db71e4487663dd5dfbb1984 | |
parent | 050ba6f45eac82c524b5ce664d16c20ce4f16628 (diff) |
Implement AMR gain function that is used by both AMR and SIPR.
Based on AMR SoC code by Robert Swain and Colin McQuillan.
Originally committed as revision 20421 to svn://svn.ffmpeg.org/ffmpeg/trunk
-rw-r--r-- | libavcodec/acelp_pitch_delay.c | 21 | ||||
-rw-r--r-- | libavcodec/acelp_pitch_delay.h | 14 |
2 files changed, 35 insertions, 0 deletions
diff --git a/libavcodec/acelp_pitch_delay.c b/libavcodec/acelp_pitch_delay.c index ac929c4689..4c809d7eeb 100644 --- a/libavcodec/acelp_pitch_delay.c +++ b/libavcodec/acelp_pitch_delay.c @@ -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; +} diff --git a/libavcodec/acelp_pitch_delay.h b/libavcodec/acelp_pitch_delay.h index 2504a9e3dd..42307d2bba 100644 --- a/libavcodec/acelp_pitch_delay.h +++ b/libavcodec/acelp_pitch_delay.h @@ -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 */ |