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Diffstat (limited to 'ffmpeg1/libavcodec/acelp_pitch_delay.h')
| -rw-r--r-- | ffmpeg1/libavcodec/acelp_pitch_delay.h | 252 |
1 files changed, 252 insertions, 0 deletions
diff --git a/ffmpeg1/libavcodec/acelp_pitch_delay.h b/ffmpeg1/libavcodec/acelp_pitch_delay.h new file mode 100644 index 0000000..72977f1 --- /dev/null +++ b/ffmpeg1/libavcodec/acelp_pitch_delay.h @@ -0,0 +1,252 @@ +/* + * 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 + */ + +#ifndef AVCODEC_ACELP_PITCH_DELAY_H +#define AVCODEC_ACELP_PITCH_DELAY_H + +#include <stdint.h> +#include "dsputil.h" + +#define PITCH_DELAY_MIN 20 +#define PITCH_DELAY_MAX 143 + +/** + * @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 + */ +int ff_acelp_decode_8bit_to_1st_delay3(int 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. + */ +int ff_acelp_decode_5_6_bit_to_2nd_delay3( + int ac_index, + int pitch_delay_min); + +/** + * @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. + */ +int ff_acelp_decode_4bit_to_2nd_delay3( + int ac_index, + int pitch_delay_min); + +/** + * @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. + */ +int ff_acelp_decode_9bit_to_1st_delay6(int ac_index); + +/** + * @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. + */ +int ff_acelp_decode_6bit_to_2nd_delay6( + int ac_index, + int pitch_delay_min); + +/** + * @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 dsp initialized dsputil 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( + DSPContext *dsp, + 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); + +#endif /* AVCODEC_ACELP_PITCH_DELAY_H */ |