Libav
|
00001 /* 00002 * gain code, gain pitch and pitch delay decoding 00003 * 00004 * Copyright (c) 2008 Vladimir Voroshilov 00005 * 00006 * This file is part of FFmpeg. 00007 * 00008 * FFmpeg is free software; you can redistribute it and/or 00009 * modify it under the terms of the GNU Lesser General Public 00010 * License as published by the Free Software Foundation; either 00011 * version 2.1 of the License, or (at your option) any later version. 00012 * 00013 * FFmpeg is distributed in the hope that it will be useful, 00014 * but WITHOUT ANY WARRANTY; without even the implied warranty of 00015 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 00016 * Lesser General Public License for more details. 00017 * 00018 * You should have received a copy of the GNU Lesser General Public 00019 * License along with FFmpeg; if not, write to the Free Software 00020 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 00021 */ 00022 00023 #include "avcodec.h" 00024 #include "dsputil.h" 00025 #include "acelp_pitch_delay.h" 00026 #include "celp_math.h" 00027 00028 int ff_acelp_decode_8bit_to_1st_delay3(int ac_index) 00029 { 00030 ac_index += 58; 00031 if(ac_index > 254) 00032 ac_index = 3 * ac_index - 510; 00033 return ac_index; 00034 } 00035 00036 int ff_acelp_decode_4bit_to_2nd_delay3( 00037 int ac_index, 00038 int pitch_delay_min) 00039 { 00040 if(ac_index < 4) 00041 return 3 * (ac_index + pitch_delay_min); 00042 else if(ac_index < 12) 00043 return 3 * pitch_delay_min + ac_index + 6; 00044 else 00045 return 3 * (ac_index + pitch_delay_min) - 18; 00046 } 00047 00048 int ff_acelp_decode_5_6_bit_to_2nd_delay3( 00049 int ac_index, 00050 int pitch_delay_min) 00051 { 00052 return 3 * pitch_delay_min + ac_index - 2; 00053 } 00054 00055 int ff_acelp_decode_9bit_to_1st_delay6(int ac_index) 00056 { 00057 if(ac_index < 463) 00058 return ac_index + 105; 00059 else 00060 return 6 * (ac_index - 368); 00061 } 00062 int ff_acelp_decode_6bit_to_2nd_delay6( 00063 int ac_index, 00064 int pitch_delay_min) 00065 { 00066 return 6 * pitch_delay_min + ac_index - 3; 00067 } 00068 00069 void ff_acelp_update_past_gain( 00070 int16_t* quant_energy, 00071 int gain_corr_factor, 00072 int log2_ma_pred_order, 00073 int erasure) 00074 { 00075 int i; 00076 int avg_gain=quant_energy[(1 << log2_ma_pred_order) - 1]; // (5.10) 00077 00078 for(i=(1 << log2_ma_pred_order) - 1; i>0; i--) 00079 { 00080 avg_gain += quant_energy[i-1]; 00081 quant_energy[i] = quant_energy[i-1]; 00082 } 00083 00084 if(erasure) 00085 quant_energy[0] = FFMAX(avg_gain >> log2_ma_pred_order, -10240) - 4096; // -10 and -4 in (5.10) 00086 else 00087 quant_energy[0] = (6165 * ((ff_log2(gain_corr_factor) >> 2) - (13 << 13))) >> 13; 00088 } 00089 00090 int16_t ff_acelp_decode_gain_code( 00091 DSPContext *dsp, 00092 int gain_corr_factor, 00093 const int16_t* fc_v, 00094 int mr_energy, 00095 const int16_t* quant_energy, 00096 const int16_t* ma_prediction_coeff, 00097 int subframe_size, 00098 int ma_pred_order) 00099 { 00100 int i; 00101 00102 mr_energy <<= 10; 00103 00104 for(i=0; i<ma_pred_order; i++) 00105 mr_energy += quant_energy[i] * ma_prediction_coeff[i]; 00106 00107 #ifdef G729_BITEXACT 00108 mr_energy += (((-6165LL * ff_log2(dsp->scalarproduct_int16(fc_v, fc_v, subframe_size, 0))) >> 3) & ~0x3ff); 00109 00110 mr_energy = (5439 * (mr_energy >> 15)) >> 8; // (0.15) = (0.15) * (7.23) 00111 00112 return bidir_sal( 00113 ((ff_exp2(mr_energy & 0x7fff) + 16) >> 5) * (gain_corr_factor >> 1), 00114 (mr_energy >> 15) - 25 00115 ); 00116 #else 00117 mr_energy = gain_corr_factor * exp(M_LN10 / (20 << 23) * mr_energy) / 00118 sqrt(dsp->scalarproduct_int16(fc_v, fc_v, subframe_size, 0)); 00119 return mr_energy >> 12; 00120 #endif 00121 } 00122 00123 float ff_amr_set_fixed_gain(float fixed_gain_factor, float fixed_mean_energy, 00124 float *prediction_error, float energy_mean, 00125 const float *pred_table) 00126 { 00127 // Equations 66-69: 00128 // ^g_c = ^gamma_gc * 100.05 (predicted dB + mean dB - dB of fixed vector) 00129 // Note 10^(0.05 * -10log(average x2)) = 1/sqrt((average x2)). 00130 float val = fixed_gain_factor * 00131 exp2f(M_LOG2_10 * 0.05 * 00132 (ff_dot_productf(pred_table, prediction_error, 4) + 00133 energy_mean)) / 00134 sqrtf(fixed_mean_energy); 00135 00136 // update quantified prediction error energy history 00137 memmove(&prediction_error[0], &prediction_error[1], 00138 3 * sizeof(prediction_error[0])); 00139 prediction_error[3] = 20.0 * log10f(fixed_gain_factor); 00140 00141 return val; 00142 } 00143 00144 void ff_decode_pitch_lag(int *lag_int, int *lag_frac, int pitch_index, 00145 const int prev_lag_int, const int subframe, 00146 int third_as_first, int resolution) 00147 { 00148 /* Note n * 10923 >> 15 is floor(x/3) for 0 <= n <= 32767 */ 00149 if (subframe == 0 || (subframe == 2 && third_as_first)) { 00150 00151 if (pitch_index < 197) 00152 pitch_index += 59; 00153 else 00154 pitch_index = 3 * pitch_index - 335; 00155 00156 } else { 00157 if (resolution == 4) { 00158 int search_range_min = av_clip(prev_lag_int - 5, PITCH_DELAY_MIN, 00159 PITCH_DELAY_MAX - 9); 00160 00161 // decoding with 4-bit resolution 00162 if (pitch_index < 4) { 00163 // integer only precision for [search_range_min, search_range_min+3] 00164 pitch_index = 3 * (pitch_index + search_range_min) + 1; 00165 } else if (pitch_index < 12) { 00166 // 1/3 fractional precision for [search_range_min+3 1/3, search_range_min+5 2/3] 00167 pitch_index += 3 * search_range_min + 7; 00168 } else { 00169 // integer only precision for [search_range_min+6, search_range_min+9] 00170 pitch_index = 3 * (pitch_index + search_range_min - 6) + 1; 00171 } 00172 } else { 00173 // decoding with 5 or 6 bit resolution, 1/3 fractional precision 00174 pitch_index--; 00175 00176 if (resolution == 5) { 00177 pitch_index += 3 * av_clip(prev_lag_int - 10, PITCH_DELAY_MIN, 00178 PITCH_DELAY_MAX - 19); 00179 } else 00180 pitch_index += 3 * av_clip(prev_lag_int - 5, PITCH_DELAY_MIN, 00181 PITCH_DELAY_MAX - 9); 00182 } 00183 } 00184 *lag_int = pitch_index * 10923 >> 15; 00185 *lag_frac = pitch_index - 3 * *lag_int - 1; 00186 }