| /* | |
| * gain code, gain pitch and pitch delay decoding | |
| * | |
| * Copyright (c) 2008 Vladimir Voroshilov | |
| * | |
| * This file is part of FFmpeg. | |
| * | |
| * FFmpeg is free software; you can redistribute it and/or | |
| * modify it under the terms of the GNU Lesser General Public | |
| * License as published by the Free Software Foundation; either | |
| * version 2.1 of the License, or (at your option) any later version. | |
| * | |
| * FFmpeg is distributed in the hope that it will be useful, | |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
| * Lesser General Public License for more details. | |
| * | |
| * You should have received a copy of the GNU Lesser General Public | |
| * License along with FFmpeg; if not, write to the Free Software | |
| * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
| */ | |
| /** | |
| * @brief Decode pitch delay of the first subframe encoded by 8 bits with 1/3 | |
| * resolution. | |
| * @param ac_index adaptive codebook index (8 bits) | |
| * | |
| * @return pitch delay in 1/3 units | |
| * | |
| * Pitch delay is coded: | |
| * with 1/3 resolution, 19 < pitch_delay < 85 | |
| * integers only, 85 <= pitch_delay <= 143 | |
| */ | |
| static inline int ff_acelp_decode_8bit_to_1st_delay3(int ac_index) | |
| { | |
| ac_index += 58; | |
| if (ac_index > 254) | |
| ac_index = 3 * ac_index - 510; | |
| return ac_index; | |
| } | |
| /** | |
| * @brief Decode pitch delay of the second subframe encoded by 5 or 6 bits | |
| * with 1/3 precision. | |
| * @param ac_index adaptive codebook index (5 or 6 bits) | |
| * @param pitch_delay_min lower bound (integer) of pitch delay interval | |
| * for second subframe | |
| * | |
| * @return pitch delay in 1/3 units | |
| * | |
| * Pitch delay is coded: | |
| * with 1/3 resolution, -6 < pitch_delay - int(prev_pitch_delay) < 5 | |
| * | |
| * @remark The routine is used in G.729 @@8k, AMR @@10.2k, AMR @@7.95k, | |
| * AMR @@7.4k for the second subframe. | |
| */ | |
| static inline int ff_acelp_decode_5_6_bit_to_2nd_delay3(int ac_index, | |
| int pitch_delay_min) | |
| { | |
| return 3 * pitch_delay_min + ac_index - 2; | |
| } | |
| /** | |
| * @brief Decode pitch delay with 1/3 precision. | |
| * @param ac_index adaptive codebook index (4 bits) | |
| * @param pitch_delay_min lower bound (integer) of pitch delay interval for | |
| * second subframe | |
| * | |
| * @return pitch delay in 1/3 units | |
| * | |
| * Pitch delay is coded: | |
| * integers only, -6 < pitch_delay - int(prev_pitch_delay) <= -2 | |
| * with 1/3 resolution, -2 < pitch_delay - int(prev_pitch_delay) < 1 | |
| * integers only, 1 <= pitch_delay - int(prev_pitch_delay) < 5 | |
| * | |
| * @remark The routine is used in G.729 @@6.4k, AMR @@6.7k, AMR @@5.9k, | |
| * AMR @@5.15k, AMR @@4.75k for the second subframe. | |
| */ | |
| static inline int ff_acelp_decode_4bit_to_2nd_delay3(int ac_index, | |
| int pitch_delay_min) | |
| { | |
| if (ac_index < 4) | |
| return 3 * (ac_index + pitch_delay_min); | |
| else if (ac_index < 12) | |
| return 3 * pitch_delay_min + ac_index + 6; | |
| else | |
| return 3 * (ac_index + pitch_delay_min) - 18; | |
| } | |
| /** | |
| * @brief Decode pitch delay of the first subframe encoded by 9 bits | |
| * with 1/6 precision. | |
| * @param ac_index adaptive codebook index (9 bits) | |
| * | |
| * @return pitch delay in 1/6 units | |
| * | |
| * Pitch delay is coded: | |
| * with 1/6 resolution, 17 < pitch_delay < 95 | |
| * integers only, 95 <= pitch_delay <= 143 | |
| * | |
| * @remark The routine is used in AMR @@12.2k for the first and third subframes. | |
| */ | |
| static inline int ff_acelp_decode_9bit_to_1st_delay6(int ac_index) | |
| { | |
| if (ac_index < 463) | |
| return ac_index + 105; | |
| else | |
| return 6 * (ac_index - 368); | |
| } | |
| /** | |
| * @brief Decode pitch delay of the second subframe encoded by 6 bits | |
| * with 1/6 precision. | |
| * @param ac_index adaptive codebook index (6 bits) | |
| * @param pitch_delay_min lower bound (integer) of pitch delay interval for | |
| * second subframe | |
| * | |
| * @return pitch delay in 1/6 units | |
| * | |
| * Pitch delay is coded: | |
| * with 1/6 resolution, -6 < pitch_delay - int(prev_pitch_delay) < 5 | |
| * | |
| * @remark The routine is used in AMR @@12.2k for the second and fourth subframes. | |
| */ | |
| static inline int ff_acelp_decode_6bit_to_2nd_delay6(int ac_index, | |
| int pitch_delay_min) | |
| { | |
| return 6 * pitch_delay_min + ac_index - 3; | |
| } | |
| /** | |
| * @brief Update past quantized energies | |
| * @param[in,out] quant_energy past quantized energies (5.10) | |
| * @param gain_corr_factor gain correction factor | |
| * @param log2_ma_pred_order log2() of MA prediction order | |
| * @param erasure frame erasure flag | |
| * | |
| * If frame erasure flag is not equal to zero, memory is updated with | |
| * averaged energy, attenuated by 4dB: | |
| * max(avg(quant_energy[i])-4, -14), i=0,ma_pred_order | |
| * | |
| * In normal mode memory is updated with | |
| * Er - Ep = 20 * log10(gain_corr_factor) | |
| * | |
| * @remark The routine is used in G.729 and AMR (all modes). | |
| */ | |
| void ff_acelp_update_past_gain( | |
| int16_t* quant_energy, | |
| int gain_corr_factor, | |
| int log2_ma_pred_order, | |
| int erasure); | |
| /** | |
| * @brief Decode the adaptive codebook gain and add | |
| * correction (4.1.5 and 3.9.1 of G.729). | |
| * @param adsp initialized audio DSP context | |
| * @param gain_corr_factor gain correction factor (2.13) | |
| * @param fc_v fixed-codebook vector (2.13) | |
| * @param mr_energy mean innovation energy and fixed-point correction (7.13) | |
| * @param[in,out] quant_energy past quantized energies (5.10) | |
| * @param subframe_size length of subframe | |
| * | |
| * @return quantized fixed-codebook gain (14.1) | |
| * | |
| * The routine implements equations 69, 66 and 71 of the G.729 specification (3.9.1) | |
| * | |
| * Em - mean innovation energy (dB, constant, depends on decoding algorithm) | |
| * Ep - mean-removed predicted energy (dB) | |
| * Er - mean-removed innovation energy (dB) | |
| * Ei - mean energy of the fixed-codebook contribution (dB) | |
| * N - subframe_size | |
| * M - MA (Moving Average) prediction order | |
| * gc - fixed-codebook gain | |
| * gc_p - predicted fixed-codebook gain | |
| * | |
| * Fixed codebook gain is computed using predicted gain gc_p and | |
| * correction factor gain_corr_factor as shown below: | |
| * | |
| * gc = gc_p * gain_corr_factor | |
| * | |
| * The predicted fixed codebook gain gc_p is found by predicting | |
| * the energy of the fixed-codebook contribution from the energy | |
| * of previous fixed-codebook contributions. | |
| * | |
| * mean = 1/N * sum(i,0,N){ fc_v[i] * fc_v[i] } | |
| * | |
| * Ei = 10log(mean) | |
| * | |
| * Er = 10log(1/N * gc^2 * mean) - Em = 20log(gc) + Ei - Em | |
| * | |
| * Replacing Er with Ep and gc with gc_p we will receive: | |
| * | |
| * Ep = 10log(1/N * gc_p^2 * mean) - Em = 20log(gc_p) + Ei - Em | |
| * | |
| * and from above: | |
| * | |
| * gc_p = 10^((Ep - Ei + Em) / 20) | |
| * | |
| * Ep is predicted using past energies and prediction coefficients: | |
| * | |
| * Ep = sum(i,0,M){ ma_prediction_coeff[i] * quant_energy[i] } | |
| * | |
| * gc_p in fixed-point arithmetic is calculated as following: | |
| * | |
| * mean = 1/N * sum(i,0,N){ (fc_v[i] / 2^13) * (fc_v[i] / 2^13) } = | |
| * = 1/N * sum(i,0,N) { fc_v[i] * fc_v[i] } / 2^26 | |
| * | |
| * Ei = 10log(mean) = -10log(N) - 10log(2^26) + | |
| * + 10log(sum(i,0,N) { fc_v[i] * fc_v[i] }) | |
| * | |
| * Ep - Ei + Em = Ep + Em + 10log(N) + 10log(2^26) - | |
| * - 10log(sum(i,0,N) { fc_v[i] * fc_v[i] }) = | |
| * = Ep + mr_energy - 10log(sum(i,0,N) { fc_v[i] * fc_v[i] }) | |
| * | |
| * gc_p = 10 ^ ((Ep - Ei + Em) / 20) = | |
| * = 2 ^ (3.3219 * (Ep - Ei + Em) / 20) = 2 ^ (0.166 * (Ep - Ei + Em)) | |
| * | |
| * where | |
| * | |
| * mr_energy = Em + 10log(N) + 10log(2^26) | |
| * | |
| * @remark The routine is used in G.729 and AMR (all modes). | |
| */ | |
| int16_t ff_acelp_decode_gain_code( | |
| AudioDSPContext *adsp, | |
| int gain_corr_factor, | |
| const int16_t* fc_v, | |
| int mr_energy, | |
| const int16_t* quant_energy, | |
| const int16_t* ma_prediction_coeff, | |
| 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_mean_energy mean 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); | |
| /** | |
| * 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); | |