#include "libavutil/common.h"#include "libavutil/libm.h"#include "libavutil/mathematics.h"#include "avcodec.h"#include "dsputil.h"#include "acelp_pitch_delay.h"#include "celp_math.h"Go to the source code of this file.
Functions | |
| int | ff_acelp_decode_8bit_to_1st_delay3 (int ac_index) |
| Decode pitch delay of the first subframe encoded by 8 bits with 1/3 resolution. | |
| int | ff_acelp_decode_4bit_to_2nd_delay3 (int ac_index, int pitch_delay_min) |
| Decode pitch delay with 1/3 precision. | |
| int | ff_acelp_decode_5_6_bit_to_2nd_delay3 (int ac_index, int pitch_delay_min) |
| Decode pitch delay of the second subframe encoded by 5 or 6 bits with 1/3 precision. | |
| int | ff_acelp_decode_9bit_to_1st_delay6 (int ac_index) |
| Decode pitch delay of the first subframe encoded by 9 bits with 1/6 precision. | |
| int | ff_acelp_decode_6bit_to_2nd_delay6 (int ac_index, int pitch_delay_min) |
| Decode pitch delay of the second subframe encoded by 6 bits with 1/6 precision. | |
| void | ff_acelp_update_past_gain (int16_t *quant_energy, int gain_corr_factor, int log2_ma_pred_order, int erasure) |
| Update past quantized energies. | |
| 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 ma_pred_order) |
| Decode the adaptive codebook gain and add correction (4.1.5 and 3.9.1 of G.729). | |
| float | ff_amr_set_fixed_gain (float fixed_gain_factor, float fixed_mean_energy, float *prediction_error, float energy_mean, const float *pred_table) |
| Calculate fixed gain (part of section 6.1.3 of AMR spec). | |
| 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) |
| Decode the adaptive codebook index to the integer and fractional parts of the pitch lag for one subframe at 1/3 fractional precision. | |
Decode pitch delay with 1/3 precision.
| ac_index | adaptive codebook index (4 bits) | |
| pitch_delay_min | lower bound (integer) of pitch delay interval for second subframe |
Definition at line 39 of file acelp_pitch_delay.c.
Referenced by decode_frame().
Decode pitch delay of the second subframe encoded by 5 or 6 bits with 1/3 precision.
| ac_index | adaptive codebook index (5 or 6 bits) | |
| pitch_delay_min | lower bound (integer) of pitch delay interval for second subframe |
Definition at line 51 of file acelp_pitch_delay.c.
Referenced by decode_frame().
Decode pitch delay of the second subframe encoded by 6 bits with 1/6 precision.
| ac_index | adaptive codebook index (6 bits) | |
| pitch_delay_min | lower bound (integer) of pitch delay interval for second subframe |
Definition at line 65 of file acelp_pitch_delay.c.
Decode pitch delay of the first subframe encoded by 8 bits with 1/3 resolution.
| ac_index | adaptive codebook index (8 bits) |
Definition at line 31 of file acelp_pitch_delay.c.
Referenced by decode_frame().
Decode pitch delay of the first subframe encoded by 9 bits with 1/6 precision.
| ac_index | adaptive codebook index (9 bits) |
Definition at line 58 of file acelp_pitch_delay.c.
| 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 | |||
| ) |
Decode the adaptive codebook gain and add correction (4.1.5 and 3.9.1 of G.729).
| dsp | initialized dsputil context | |
| gain_corr_factor | gain correction factor (2.13) | |
| fc_v | fixed-codebook vector (2.13) | |
| mr_energy | mean innovation energy and fixed-point correction (7.13) | |
| [in,out] | quant_energy | past quantized energies (5.10) |
| subframe_size | length of subframe |
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) -
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)
Definition at line 93 of file acelp_pitch_delay.c.
Referenced by decode_frame().
| void ff_acelp_update_past_gain | ( | int16_t * | quant_energy, | |
| int | gain_corr_factor, | |||
| int | log2_ma_pred_order, | |||
| int | erasure | |||
| ) |
Update past quantized energies.
| [in,out] | quant_energy | past quantized energies (5.10) |
| gain_corr_factor | gain correction factor | |
| log2_ma_pred_order | log2() of MA prediction order | |
| erasure | frame erasure flag |
In normal mode memory is updated with Er - Ep = 20 * log10(gain_corr_factor)
Definition at line 72 of file acelp_pitch_delay.c.
Referenced by decode_frame().
| float ff_amr_set_fixed_gain | ( | float | fixed_gain_factor, | |
| float | fixed_mean_energy, | |||
| float * | prediction_error, | |||
| float | energy_mean, | |||
| const float * | pred_table | |||
| ) |
Calculate fixed gain (part of section 6.1.3 of AMR spec).
| fixed_gain_factor | gain correction factor | |
| fixed_mean_energy | mean decoded algebraic codebook vector energy | |
| prediction_error | vector of the quantified predictor errors of the four previous subframes. It is updated by this function. | |
| energy_mean | desired mean innovation energy | |
| pred_table | table of four moving average coefficients |
Definition at line 126 of file acelp_pitch_delay.c.
Referenced by amrnb_decode_frame(), amrwb_decode_frame(), and decode_frame().
| 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 | |||
| ) |
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.
| lag_int | integer part of pitch lag of the current subframe | |
| lag_frac | fractional part of pitch lag of the current subframe | |
| pitch_index | parsed adaptive codebook (pitch) index | |
| prev_lag_int | integer part of pitch lag for the previous subframe | |
| subframe | current subframe number | |
| third_as_first | treat the third frame the same way as the first |
Definition at line 147 of file acelp_pitch_delay.c.
Referenced by decode_frame(), and decode_pitch_vector().
1.5.8