yading@10: /* yading@10: * gain code, gain pitch and pitch delay decoding yading@10: * yading@10: * Copyright (c) 2008 Vladimir Voroshilov yading@10: * yading@10: * This file is part of FFmpeg. yading@10: * yading@10: * FFmpeg is free software; you can redistribute it and/or yading@10: * modify it under the terms of the GNU Lesser General Public yading@10: * License as published by the Free Software Foundation; either yading@10: * version 2.1 of the License, or (at your option) any later version. yading@10: * yading@10: * FFmpeg is distributed in the hope that it will be useful, yading@10: * but WITHOUT ANY WARRANTY; without even the implied warranty of yading@10: * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU yading@10: * Lesser General Public License for more details. yading@10: * yading@10: * You should have received a copy of the GNU Lesser General Public yading@10: * License along with FFmpeg; if not, write to the Free Software yading@10: * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA yading@10: */ yading@10: yading@10: #ifndef AVCODEC_ACELP_PITCH_DELAY_H yading@10: #define AVCODEC_ACELP_PITCH_DELAY_H yading@10: yading@10: #include yading@10: #include "dsputil.h" yading@10: yading@10: #define PITCH_DELAY_MIN 20 yading@10: #define PITCH_DELAY_MAX 143 yading@10: yading@10: /** yading@10: * @brief Decode pitch delay of the first subframe encoded by 8 bits with 1/3 yading@10: * resolution. yading@10: * @param ac_index adaptive codebook index (8 bits) yading@10: * yading@10: * @return pitch delay in 1/3 units yading@10: * yading@10: * Pitch delay is coded: yading@10: * with 1/3 resolution, 19 < pitch_delay < 85 yading@10: * integers only, 85 <= pitch_delay <= 143 yading@10: */ yading@10: int ff_acelp_decode_8bit_to_1st_delay3(int ac_index); yading@10: yading@10: /** yading@10: * @brief Decode pitch delay of the second subframe encoded by 5 or 6 bits yading@10: * with 1/3 precision. yading@10: * @param ac_index adaptive codebook index (5 or 6 bits) yading@10: * @param pitch_delay_min lower bound (integer) of pitch delay interval yading@10: * for second subframe yading@10: * yading@10: * @return pitch delay in 1/3 units yading@10: * yading@10: * Pitch delay is coded: yading@10: * with 1/3 resolution, -6 < pitch_delay - int(prev_pitch_delay) < 5 yading@10: * yading@10: * @remark The routine is used in G.729 @@8k, AMR @@10.2k, AMR @@7.95k, yading@10: * AMR @@7.4k for the second subframe. yading@10: */ yading@10: int ff_acelp_decode_5_6_bit_to_2nd_delay3( yading@10: int ac_index, yading@10: int pitch_delay_min); yading@10: yading@10: /** yading@10: * @brief Decode pitch delay with 1/3 precision. yading@10: * @param ac_index adaptive codebook index (4 bits) yading@10: * @param pitch_delay_min lower bound (integer) of pitch delay interval for yading@10: * second subframe yading@10: * yading@10: * @return pitch delay in 1/3 units yading@10: * yading@10: * Pitch delay is coded: yading@10: * integers only, -6 < pitch_delay - int(prev_pitch_delay) <= -2 yading@10: * with 1/3 resolution, -2 < pitch_delay - int(prev_pitch_delay) < 1 yading@10: * integers only, 1 <= pitch_delay - int(prev_pitch_delay) < 5 yading@10: * yading@10: * @remark The routine is used in G.729 @@6.4k, AMR @@6.7k, AMR @@5.9k, yading@10: * AMR @@5.15k, AMR @@4.75k for the second subframe. yading@10: */ yading@10: int ff_acelp_decode_4bit_to_2nd_delay3( yading@10: int ac_index, yading@10: int pitch_delay_min); yading@10: yading@10: /** yading@10: * @brief Decode pitch delay of the first subframe encoded by 9 bits yading@10: * with 1/6 precision. yading@10: * @param ac_index adaptive codebook index (9 bits) yading@10: * yading@10: * @return pitch delay in 1/6 units yading@10: * yading@10: * Pitch delay is coded: yading@10: * with 1/6 resolution, 17 < pitch_delay < 95 yading@10: * integers only, 95 <= pitch_delay <= 143 yading@10: * yading@10: * @remark The routine is used in AMR @@12.2k for the first and third subframes. yading@10: */ yading@10: int ff_acelp_decode_9bit_to_1st_delay6(int ac_index); yading@10: yading@10: /** yading@10: * @brief Decode pitch delay of the second subframe encoded by 6 bits yading@10: * with 1/6 precision. yading@10: * @param ac_index adaptive codebook index (6 bits) yading@10: * @param pitch_delay_min lower bound (integer) of pitch delay interval for yading@10: * second subframe yading@10: * yading@10: * @return pitch delay in 1/6 units yading@10: * yading@10: * Pitch delay is coded: yading@10: * with 1/6 resolution, -6 < pitch_delay - int(prev_pitch_delay) < 5 yading@10: * yading@10: * @remark The routine is used in AMR @@12.2k for the second and fourth subframes. yading@10: */ yading@10: int ff_acelp_decode_6bit_to_2nd_delay6( yading@10: int ac_index, yading@10: int pitch_delay_min); yading@10: yading@10: /** yading@10: * @brief Update past quantized energies yading@10: * @param[in,out] quant_energy past quantized energies (5.10) yading@10: * @param gain_corr_factor gain correction factor yading@10: * @param log2_ma_pred_order log2() of MA prediction order yading@10: * @param erasure frame erasure flag yading@10: * yading@10: * If frame erasure flag is not equal to zero, memory is updated with yading@10: * averaged energy, attenuated by 4dB: yading@10: * max(avg(quant_energy[i])-4, -14), i=0,ma_pred_order yading@10: * yading@10: * In normal mode memory is updated with yading@10: * Er - Ep = 20 * log10(gain_corr_factor) yading@10: * yading@10: * @remark The routine is used in G.729 and AMR (all modes). yading@10: */ yading@10: void ff_acelp_update_past_gain( yading@10: int16_t* quant_energy, yading@10: int gain_corr_factor, yading@10: int log2_ma_pred_order, yading@10: int erasure); yading@10: yading@10: /** yading@10: * @brief Decode the adaptive codebook gain and add yading@10: * correction (4.1.5 and 3.9.1 of G.729). yading@10: * @param dsp initialized dsputil context yading@10: * @param gain_corr_factor gain correction factor (2.13) yading@10: * @param fc_v fixed-codebook vector (2.13) yading@10: * @param mr_energy mean innovation energy and fixed-point correction (7.13) yading@10: * @param[in,out] quant_energy past quantized energies (5.10) yading@10: * @param subframe_size length of subframe yading@10: * yading@10: * @return quantized fixed-codebook gain (14.1) yading@10: * yading@10: * The routine implements equations 69, 66 and 71 of the G.729 specification (3.9.1) yading@10: * yading@10: * Em - mean innovation energy (dB, constant, depends on decoding algorithm) yading@10: * Ep - mean-removed predicted energy (dB) yading@10: * Er - mean-removed innovation energy (dB) yading@10: * Ei - mean energy of the fixed-codebook contribution (dB) yading@10: * N - subframe_size yading@10: * M - MA (Moving Average) prediction order yading@10: * gc - fixed-codebook gain yading@10: * gc_p - predicted fixed-codebook gain yading@10: * yading@10: * Fixed codebook gain is computed using predicted gain gc_p and yading@10: * correction factor gain_corr_factor as shown below: yading@10: * yading@10: * gc = gc_p * gain_corr_factor yading@10: * yading@10: * The predicted fixed codebook gain gc_p is found by predicting yading@10: * the energy of the fixed-codebook contribution from the energy yading@10: * of previous fixed-codebook contributions. yading@10: * yading@10: * mean = 1/N * sum(i,0,N){ fc_v[i] * fc_v[i] } yading@10: * yading@10: * Ei = 10log(mean) yading@10: * yading@10: * Er = 10log(1/N * gc^2 * mean) - Em = 20log(gc) + Ei - Em yading@10: * yading@10: * Replacing Er with Ep and gc with gc_p we will receive: yading@10: * yading@10: * Ep = 10log(1/N * gc_p^2 * mean) - Em = 20log(gc_p) + Ei - Em yading@10: * yading@10: * and from above: yading@10: * yading@10: * gc_p = 10^((Ep - Ei + Em) / 20) yading@10: * yading@10: * Ep is predicted using past energies and prediction coefficients: yading@10: * yading@10: * Ep = sum(i,0,M){ ma_prediction_coeff[i] * quant_energy[i] } yading@10: * yading@10: * gc_p in fixed-point arithmetic is calculated as following: yading@10: * yading@10: * mean = 1/N * sum(i,0,N){ (fc_v[i] / 2^13) * (fc_v[i] / 2^13) } = yading@10: * = 1/N * sum(i,0,N) { fc_v[i] * fc_v[i] } / 2^26 yading@10: * yading@10: * Ei = 10log(mean) = -10log(N) - 10log(2^26) + yading@10: * + 10log(sum(i,0,N) { fc_v[i] * fc_v[i] }) yading@10: * yading@10: * Ep - Ei + Em = Ep + Em + 10log(N) + 10log(2^26) - yading@10: * - 10log(sum(i,0,N) { fc_v[i] * fc_v[i] }) = yading@10: * = Ep + mr_energy - 10log(sum(i,0,N) { fc_v[i] * fc_v[i] }) yading@10: * yading@10: * gc_p = 10 ^ ((Ep - Ei + Em) / 20) = yading@10: * = 2 ^ (3.3219 * (Ep - Ei + Em) / 20) = 2 ^ (0.166 * (Ep - Ei + Em)) yading@10: * yading@10: * where yading@10: * yading@10: * mr_energy = Em + 10log(N) + 10log(2^26) yading@10: * yading@10: * @remark The routine is used in G.729 and AMR (all modes). yading@10: */ yading@10: int16_t ff_acelp_decode_gain_code( yading@10: DSPContext *dsp, yading@10: int gain_corr_factor, yading@10: const int16_t* fc_v, yading@10: int mr_energy, yading@10: const int16_t* quant_energy, yading@10: const int16_t* ma_prediction_coeff, yading@10: int subframe_size, yading@10: int max_pred_order); yading@10: yading@10: /** yading@10: * Calculate fixed gain (part of section 6.1.3 of AMR spec) yading@10: * yading@10: * @param fixed_gain_factor gain correction factor yading@10: * @param fixed_mean_energy mean decoded algebraic codebook vector energy yading@10: * @param prediction_error vector of the quantified predictor errors of yading@10: * the four previous subframes. It is updated by this function. yading@10: * @param energy_mean desired mean innovation energy yading@10: * @param pred_table table of four moving average coefficients yading@10: */ yading@10: float ff_amr_set_fixed_gain(float fixed_gain_factor, float fixed_mean_energy, yading@10: float *prediction_error, float energy_mean, yading@10: const float *pred_table); yading@10: yading@10: yading@10: /** yading@10: * Decode the adaptive codebook index to the integer and fractional parts yading@10: * of the pitch lag for one subframe at 1/3 fractional precision. yading@10: * yading@10: * The choice of pitch lag is described in 3GPP TS 26.090 section 5.6.1. yading@10: * yading@10: * @param lag_int integer part of pitch lag of the current subframe yading@10: * @param lag_frac fractional part of pitch lag of the current subframe yading@10: * @param pitch_index parsed adaptive codebook (pitch) index yading@10: * @param prev_lag_int integer part of pitch lag for the previous subframe yading@10: * @param subframe current subframe number yading@10: * @param third_as_first treat the third frame the same way as the first yading@10: */ yading@10: void ff_decode_pitch_lag(int *lag_int, int *lag_frac, int pitch_index, yading@10: const int prev_lag_int, const int subframe, yading@10: int third_as_first, int resolution); yading@10: yading@10: #endif /* AVCODEC_ACELP_PITCH_DELAY_H */