#include <stdint.h>
#include "dsputil.h"
Go to the source code of this file.
Defines | |
#define | PITCH_DELAY_MIN 20 |
#define | PITCH_DELAY_MAX 143 |
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_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_4bit_to_2nd_delay3 (int ac_index, int pitch_delay_min) |
Decode pitch delay 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 max_pred_order) |
Decode the adaptive codebook gain and add correction (4.1.5 and 3.9.1 of G.729). |
#define PITCH_DELAY_MAX 143 |
Definition at line 30 of file acelp_pitch_delay.h.
#define PITCH_DELAY_MIN 20 |
Definition at line 29 of file acelp_pitch_delay.h.
int ff_acelp_decode_4bit_to_2nd_delay3 | ( | int | ac_index, | |
int | pitch_delay_min | |||
) |
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 36 of file acelp_pitch_delay.c.
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.
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 48 of file acelp_pitch_delay.c.
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.
ac_index | adaptive codebook index (6 bits) | |
pitch_delay_min | lower bound (integer) of pitch delay interval for second subframe |
Definition at line 62 of file acelp_pitch_delay.c.
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.
ac_index | adaptive codebook index (8 bits) |
Definition at line 28 of file acelp_pitch_delay.c.
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.
ac_index | adaptive codebook index (9 bits) | |
pitch_delay_min | lower bound (integer) of pitch delay interval for second subframe |
Definition at line 55 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) | |
quant_energy | [in/out] past quantized energies (5.10) | |
subframe_size | length of subframe | |
ma_pred_order | MA prediction order |
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 90 of file acelp_pitch_delay.c.
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.
quant_energy | [in/out] 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 69 of file acelp_pitch_delay.c.