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FFmpeg4/libavcodec/evrcdec.c

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/*
* Enhanced Variable Rate Codec, Service Option 3 decoder
* Copyright (c) 2013 Paul B Mahol
*
* 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
*/
/**
* @file
* Enhanced Variable Rate Codec, Service Option 3 decoder
* @author Paul B Mahol
*/
#include "libavutil/mathematics.h"
#include "libavutil/opt.h"
#include "avcodec.h"
#include "internal.h"
#include "get_bits.h"
#include "evrcdata.h"
#include "acelp_vectors.h"
#include "lsp.h"
#define MIN_LSP_SEP (0.05 / (2.0 * M_PI))
#define MIN_DELAY 20
#define MAX_DELAY 120
#define NB_SUBFRAMES 3
#define SUBFRAME_SIZE 54
#define FILTER_ORDER 10
#define ACB_SIZE 128
typedef enum {
RATE_ERRS = -1,
SILENCE,
RATE_QUANT,
RATE_QUARTER,
RATE_HALF,
RATE_FULL,
} evrc_packet_rate;
/**
* EVRC-A unpacked data frame
*/
typedef struct EVRCAFrame {
uint8_t lpc_flag; ///< spectral change indicator
uint16_t lsp[4]; ///< index into LSP codebook
uint8_t pitch_delay; ///< pitch delay for entire frame
uint8_t delay_diff; ///< delay difference for entire frame
uint8_t acb_gain[3]; ///< adaptive codebook gain
uint16_t fcb_shape[3][4]; ///< fixed codebook shape
uint8_t fcb_gain[3]; ///< fixed codebook gain index
uint8_t energy_gain; ///< frame energy gain index
uint8_t tty; ///< tty baud rate bit
} EVRCAFrame;
typedef struct EVRCContext {
AVClass *class;
int postfilter;
GetBitContext gb;
evrc_packet_rate bitrate;
evrc_packet_rate last_valid_bitrate;
EVRCAFrame frame;
float lspf[FILTER_ORDER];
float prev_lspf[FILTER_ORDER];
float synthesis[FILTER_ORDER];
float postfilter_fir[FILTER_ORDER];
float postfilter_iir[FILTER_ORDER];
float postfilter_residual[ACB_SIZE + SUBFRAME_SIZE];
float pitch_delay;
float prev_pitch_delay;
float avg_acb_gain; ///< average adaptive codebook gain
float avg_fcb_gain; ///< average fixed codebook gain
float pitch[ACB_SIZE + FILTER_ORDER + SUBFRAME_SIZE];
float pitch_back[ACB_SIZE];
float interpolation_coeffs[136];
float energy_vector[NB_SUBFRAMES];
float fade_scale;
float last;
uint8_t prev_energy_gain;
uint8_t prev_error_flag;
uint8_t warned_buf_mismatch_bitrate;
} EVRCContext;
/**
* Frame unpacking for RATE_FULL, RATE_HALF and RATE_QUANT
*
* @param e the context
*
* TIA/IS-127 Table 4.21-1
*/
static void unpack_frame(EVRCContext *e)
{
EVRCAFrame *frame = &e->frame;
GetBitContext *gb = &e->gb;
switch (e->bitrate) {
case RATE_FULL:
frame->lpc_flag = get_bits1(gb);
frame->lsp[0] = get_bits(gb, 6);
frame->lsp[1] = get_bits(gb, 6);
frame->lsp[2] = get_bits(gb, 9);
frame->lsp[3] = get_bits(gb, 7);
frame->pitch_delay = get_bits(gb, 7);
frame->delay_diff = get_bits(gb, 5);
frame->acb_gain[0] = get_bits(gb, 3);
frame->fcb_shape[0][0] = get_bits(gb, 8);
frame->fcb_shape[0][1] = get_bits(gb, 8);
frame->fcb_shape[0][2] = get_bits(gb, 8);
frame->fcb_shape[0][3] = get_bits(gb, 11);
frame->fcb_gain[0] = get_bits(gb, 5);
frame->acb_gain[1] = get_bits(gb, 3);
frame->fcb_shape[1][0] = get_bits(gb, 8);
frame->fcb_shape[1][1] = get_bits(gb, 8);
frame->fcb_shape[1][2] = get_bits(gb, 8);
frame->fcb_shape[1][3] = get_bits(gb, 11);
frame->fcb_gain [1] = get_bits(gb, 5);
frame->acb_gain [2] = get_bits(gb, 3);
frame->fcb_shape[2][0] = get_bits(gb, 8);
frame->fcb_shape[2][1] = get_bits(gb, 8);
frame->fcb_shape[2][2] = get_bits(gb, 8);
frame->fcb_shape[2][3] = get_bits(gb, 11);
frame->fcb_gain [2] = get_bits(gb, 5);
frame->tty = get_bits1(gb);
break;
case RATE_HALF:
frame->lsp [0] = get_bits(gb, 7);
frame->lsp [1] = get_bits(gb, 7);
frame->lsp [2] = get_bits(gb, 8);
frame->pitch_delay = get_bits(gb, 7);
frame->acb_gain [0] = get_bits(gb, 3);
frame->fcb_shape[0][0] = get_bits(gb, 10);
frame->fcb_gain [0] = get_bits(gb, 4);
frame->acb_gain [1] = get_bits(gb, 3);
frame->fcb_shape[1][0] = get_bits(gb, 10);
frame->fcb_gain [1] = get_bits(gb, 4);
frame->acb_gain [2] = get_bits(gb, 3);
frame->fcb_shape[2][0] = get_bits(gb, 10);
frame->fcb_gain [2] = get_bits(gb, 4);
break;
case RATE_QUANT:
frame->lsp [0] = get_bits(gb, 4);
frame->lsp [1] = get_bits(gb, 4);
frame->energy_gain = get_bits(gb, 8);
break;
}
}
static evrc_packet_rate buf_size2bitrate(const int buf_size)
{
switch (buf_size) {
case 23: return RATE_FULL;
case 11: return RATE_HALF;
case 6: return RATE_QUARTER;
case 3: return RATE_QUANT;
case 1: return SILENCE;
}
return RATE_ERRS;
}
/**
* Determine the bitrate from the frame size and/or the first byte of the frame.
*
* @param avctx the AV codec context
* @param buf_size length of the buffer
* @param buf the bufffer
*
* @return the bitrate on success,
* RATE_ERRS if the bitrate cannot be satisfactorily determined
*/
static evrc_packet_rate determine_bitrate(AVCodecContext *avctx,
int *buf_size,
const uint8_t **buf)
{
evrc_packet_rate bitrate;
if ((bitrate = buf_size2bitrate(*buf_size)) >= 0) {
if (bitrate > **buf) {
EVRCContext *e = avctx->priv_data;
if (!e->warned_buf_mismatch_bitrate) {
av_log(avctx, AV_LOG_WARNING,
"Claimed bitrate and buffer size mismatch.\n");
e->warned_buf_mismatch_bitrate = 1;
}
bitrate = **buf;
} else if (bitrate < **buf) {
av_log(avctx, AV_LOG_ERROR,
"Buffer is too small for the claimed bitrate.\n");
return RATE_ERRS;
}
(*buf)++;
*buf_size -= 1;
} else if ((bitrate = buf_size2bitrate(*buf_size + 1)) >= 0) {
av_log(avctx, AV_LOG_DEBUG,
"Bitrate byte is missing, guessing the bitrate from packet size.\n");
} else
return RATE_ERRS;
return bitrate;
}
static void warn_insufficient_frame_quality(AVCodecContext *avctx,
const char *message)
{
av_log(avctx, AV_LOG_WARNING, "Frame #%d, %s\n",
avctx->frame_number, message);
}
/**
* Initialize the speech codec according to the specification.
*
* TIA/IS-127 5.2
*/
static av_cold int evrc_decode_init(AVCodecContext *avctx)
{
EVRCContext *e = avctx->priv_data;
int i, n, idx = 0;
float denom = 2.0 / (2.0 * 8.0 + 1.0);
avctx->channels = 1;
avctx->channel_layout = AV_CH_LAYOUT_MONO;
avctx->sample_fmt = AV_SAMPLE_FMT_FLT;
for (i = 0; i < FILTER_ORDER; i++) {
e->prev_lspf[i] = (i + 1) * 0.048;
e->synthesis[i] = 0.0;
}
for (i = 0; i < ACB_SIZE; i++)
e->pitch[i] = e->pitch_back[i] = 0.0;
e->last_valid_bitrate = RATE_QUANT;
e->prev_pitch_delay = 40.0;
e->fade_scale = 1.0;
e->prev_error_flag = 0;
e->avg_acb_gain = e->avg_fcb_gain = 0.0;
for (i = 0; i < 8; i++) {
float tt = ((float)i - 8.0 / 2.0) / 8.0;
for (n = -8; n <= 8; n++, idx++) {
float arg1 = M_PI * 0.9 * (tt - n);
float arg2 = M_PI * (tt - n);
e->interpolation_coeffs[idx] = 0.9;
if (arg1)
e->interpolation_coeffs[idx] *= (0.54 + 0.46 * cos(arg2 * denom)) *
sin(arg1) / arg1;
}
}
return 0;
}
/**
* Decode the 10 vector quantized line spectral pair frequencies from the LSP
* transmission codes of any bitrate and check for badly received packets.
*
* @param e the context
*
* @return 0 on success, -1 if the packet is badly received
*
* TIA/IS-127 5.2.1, 5.7.1
*/
static int decode_lspf(EVRCContext *e)
{
const float * const *codebooks = evrc_lspq_codebooks[e->bitrate];
int i, j, k = 0;
for (i = 0; i < evrc_lspq_nb_codebooks[e->bitrate]; i++) {
int row_size = evrc_lspq_codebooks_row_sizes[e->bitrate][i];
const float *codebook = codebooks[i];
for (j = 0; j < row_size; j++)
e->lspf[k++] = codebook[e->frame.lsp[i] * row_size + j];
}
// check for monotonic LSPs
for (i = 1; i < FILTER_ORDER; i++)
if (e->lspf[i] <= e->lspf[i - 1])
return -1;
// check for minimum separation of LSPs at the splits
for (i = 0, k = 0; i < evrc_lspq_nb_codebooks[e->bitrate] - 1; i++) {
k += evrc_lspq_codebooks_row_sizes[e->bitrate][i];
if (e->lspf[k] - e->lspf[k - 1] <= MIN_LSP_SEP)
return -1;
}
return 0;
}
/*
* Interpolation of LSP parameters.
*
* TIA/IS-127 5.2.3.1, 5.7.3.2
*/
static void interpolate_lsp(float *ilsp, const float *lsp,
const float *prev, int index)
{
static const float lsp_interpolation_factors[] = { 0.1667, 0.5, 0.8333 };
ff_weighted_vector_sumf(ilsp, prev, lsp,
1.0 - lsp_interpolation_factors[index],
lsp_interpolation_factors[index], FILTER_ORDER);
}
/*
* Reconstruction of the delay contour.
*
* TIA/IS-127 5.2.2.3.2
*/
static void interpolate_delay(float *dst, float current, float prev, int index)
{
static const float d_interpolation_factors[] = { 0, 0.3313, 0.6625, 1, 1 };
dst[0] = (1.0 - d_interpolation_factors[index ]) * prev
+ d_interpolation_factors[index ] * current;
dst[1] = (1.0 - d_interpolation_factors[index + 1]) * prev
+ d_interpolation_factors[index + 1] * current;
dst[2] = (1.0 - d_interpolation_factors[index + 2]) * prev
+ d_interpolation_factors[index + 2] * current;
}
/*
* Convert the quantized, interpolated line spectral frequencies,
* to prediction coefficients.
*
* TIA/IS-127 5.2.3.2, 4.7.2.2
*/
static void decode_predictor_coeffs(const float *ilspf, float *ilpc)
{
double lsp[FILTER_ORDER];
float a[FILTER_ORDER / 2 + 1], b[FILTER_ORDER / 2 + 1];
float a1[FILTER_ORDER / 2] = { 0 };
float a2[FILTER_ORDER / 2] = { 0 };
float b1[FILTER_ORDER / 2] = { 0 };
float b2[FILTER_ORDER / 2] = { 0 };
int i, k;
ff_acelp_lsf2lspd(lsp, ilspf, FILTER_ORDER);
for (k = 0; k <= FILTER_ORDER; k++) {
a[0] = k < 2 ? 0.25 : 0;
b[0] = k < 2 ? k < 1 ? 0.25 : -0.25 : 0;
for (i = 0; i < FILTER_ORDER / 2; i++) {
a[i + 1] = a[i] - 2 * lsp[i * 2 ] * a1[i] + a2[i];
b[i + 1] = b[i] - 2 * lsp[i * 2 + 1] * b1[i] + b2[i];
a2[i] = a1[i];
a1[i] = a[i];
b2[i] = b1[i];
b1[i] = b[i];
}
if (k)
ilpc[k - 1] = 2.0 * (a[FILTER_ORDER / 2] + b[FILTER_ORDER / 2]);
}
}
static void bl_intrp(EVRCContext *e, float *ex, float delay)
{
float *f;
int offset, i, coef_idx;
int16_t t;
offset = lrintf(delay);
t = (offset - delay + 0.5) * 8.0 + 0.5;
if (t == 8) {
t = 0;
offset--;
}
f = ex - offset - 8;
coef_idx = t * (2 * 8 + 1);
ex[0] = 0.0;
for (i = 0; i < 2 * 8 + 1; i++)
ex[0] += e->interpolation_coeffs[coef_idx + i] * f[i];
}
/*
* Adaptive codebook excitation.
*
* TIA/IS-127 5.2.2.3.3, 4.12.5.2
*/
static void acb_excitation(EVRCContext *e, float *excitation, float gain,
const float delay[3], int length)
{
float denom, locdelay, dpr, invl;
int i;
invl = 1.0 / ((float) length);
dpr = length;
/* first at-most extra samples */
denom = (delay[1] - delay[0]) * invl;
for (i = 0; i < dpr; i++) {
locdelay = delay[0] + i * denom;
bl_intrp(e, excitation + i, locdelay);
}
denom = (delay[2] - delay[1]) * invl;
/* interpolation */
for (i = dpr; i < dpr + 10; i++) {
locdelay = delay[1] + (i - dpr) * denom;
bl_intrp(e, excitation + i, locdelay);
}
for (i = 0; i < length; i++)
excitation[i] *= gain;
}
static void decode_8_pulses_35bits(const uint16_t *fixed_index, float *cod)
{
int i, pos1, pos2, offset;
offset = (fixed_index[3] >> 9) & 3;
for (i = 0; i < 3; i++) {
pos1 = ((fixed_index[i] & 0x7f) / 11) * 5 + ((i + offset) % 5);
pos2 = ((fixed_index[i] & 0x7f) % 11) * 5 + ((i + offset) % 5);
cod[pos1] = (fixed_index[i] & 0x80) ? -1.0 : 1.0;
if (pos2 < pos1)
cod[pos2] = -cod[pos1];
else
cod[pos2] += cod[pos1];
}
pos1 = ((fixed_index[3] & 0x7f) / 11) * 5 + ((3 + offset) % 5);
pos2 = ((fixed_index[3] & 0x7f) % 11) * 5 + ((4 + offset) % 5);
cod[pos1] = (fixed_index[3] & 0x100) ? -1.0 : 1.0;
cod[pos2] = (fixed_index[3] & 0x80 ) ? -1.0 : 1.0;
}
static void decode_3_pulses_10bits(uint16_t fixed_index, float *cod)
{
float sign;
int pos;
sign = (fixed_index & 0x200) ? -1.0 : 1.0;
pos = ((fixed_index & 0x7) * 7) + 4;
cod[pos] += sign;
pos = (((fixed_index >> 3) & 0x7) * 7) + 2;
cod[pos] -= sign;
pos = (((fixed_index >> 6) & 0x7) * 7);
cod[pos] += sign;
}
/*
* Reconstruction of ACELP fixed codebook excitation for full and half rate.
*
* TIA/IS-127 5.2.3.7
*/
static void fcb_excitation(EVRCContext *e, const uint16_t *codebook,
float *excitation, float pitch_gain,
int pitch_lag, int subframe_size)
{
int i;
if (e->bitrate == RATE_FULL)
decode_8_pulses_35bits(codebook, excitation);
else
decode_3_pulses_10bits(*codebook, excitation);
pitch_gain = av_clipf(pitch_gain, 0.2, 0.9);
for (i = pitch_lag; i < subframe_size; i++)
excitation[i] += pitch_gain * excitation[i - pitch_lag];
}
/**
* Synthesis of the decoder output signal.
*
* param[in] in input signal
* param[in] filter_coeffs LPC coefficients
* param[in/out] memory synthesis filter memory
* param buffer_length amount of data to process
* param[out] samples output samples
*
* TIA/IS-127 5.2.3.15, 5.7.3.4
*/
static void synthesis_filter(const float *in, const float *filter_coeffs,
float *memory, int buffer_length, float *samples)
{
int i, j;
for (i = 0; i < buffer_length; i++) {
samples[i] = in[i];
for (j = FILTER_ORDER - 1; j > 0; j--) {
samples[i] -= filter_coeffs[j] * memory[j];
memory[j] = memory[j - 1];
}
samples[i] -= filter_coeffs[0] * memory[0];
memory[0] = samples[i];
}
}
static void bandwidth_expansion(float *coeff, const float *inbuf, float gamma)
{
double fac = gamma;
int i;
for (i = 0; i < FILTER_ORDER; i++) {
coeff[i] = inbuf[i] * fac;
fac *= gamma;
}
}
static void residual_filter(float *output, const float *input,
const float *coef, float *memory, int length)
{
float sum;
int i, j;
for (i = 0; i < length; i++) {
sum = input[i];
for (j = FILTER_ORDER - 1; j > 0; j--) {
sum += coef[j] * memory[j];
memory[j] = memory[j - 1];
}
sum += coef[0] * memory[0];
memory[0] = input[i];
output[i] = sum;
}
}
/*
* TIA/IS-127 Table 5.9.1-1.
*/
static const struct PfCoeff {
float tilt;
float ltgain;
float p1;
float p2;
} postfilter_coeffs[5] = {
{ 0.0 , 0.0 , 0.0 , 0.0 },
{ 0.0 , 0.0 , 0.57, 0.57 },
{ 0.0 , 0.0 , 0.0 , 0.0 },
{ 0.35, 0.50, 0.50, 0.75 },
{ 0.20, 0.50, 0.57, 0.75 },
};
/*
* Adaptive postfilter.
*
* TIA/IS-127 5.9
*/
static void postfilter(EVRCContext *e, float *in, const float *coeff,
float *out, int idx, const struct PfCoeff *pfc,
int length)
{
float wcoef1[FILTER_ORDER], wcoef2[FILTER_ORDER],
scratch[SUBFRAME_SIZE], temp[SUBFRAME_SIZE],
mem[SUBFRAME_SIZE];
float sum1 = 0.0, sum2 = 0.0, gamma, gain;
float tilt = pfc->tilt;
int i, n, best;
bandwidth_expansion(wcoef1, coeff, pfc->p1);
bandwidth_expansion(wcoef2, coeff, pfc->p2);
/* Tilt compensation filter, TIA/IS-127 5.9.1 */
for (i = 0; i < length - 1; i++)
sum2 += in[i] * in[i + 1];
if (sum2 < 0.0)
tilt = 0.0;
for (i = 0; i < length; i++) {
scratch[i] = in[i] - tilt * e->last;
e->last = in[i];
}
/* Short term residual filter, TIA/IS-127 5.9.2 */
residual_filter(&e->postfilter_residual[ACB_SIZE], scratch, wcoef1, e->postfilter_fir, length);
/* Long term postfilter */
best = idx;
for (i = FFMIN(MIN_DELAY, idx - 3); i <= FFMAX(MAX_DELAY, idx + 3); i++) {
for (n = ACB_SIZE, sum2 = 0; n < ACB_SIZE + length; n++)
sum2 += e->postfilter_residual[n] * e->postfilter_residual[n - i];
if (sum2 > sum1) {
sum1 = sum2;
best = i;
}
}
for (i = ACB_SIZE, sum1 = 0; i < ACB_SIZE + length; i++)
sum1 += e->postfilter_residual[i - best] * e->postfilter_residual[i - best];
for (i = ACB_SIZE, sum2 = 0; i < ACB_SIZE + length; i++)
sum2 += e->postfilter_residual[i] * e->postfilter_residual[i - best];
if (sum2 * sum1 == 0 || e->bitrate == RATE_QUANT) {
memcpy(temp, e->postfilter_residual + ACB_SIZE, length * sizeof(float));
} else {
gamma = sum2 / sum1;
if (gamma < 0.5)
memcpy(temp, e->postfilter_residual + ACB_SIZE, length * sizeof(float));
else {
gamma = FFMIN(gamma, 1.0);
for (i = 0; i < length; i++) {
temp[i] = e->postfilter_residual[ACB_SIZE + i] + gamma *
pfc->ltgain * e->postfilter_residual[ACB_SIZE + i - best];
}
}
}
memcpy(scratch, temp, length * sizeof(float));
memcpy(mem, e->postfilter_iir, FILTER_ORDER * sizeof(float));
synthesis_filter(scratch, wcoef2, mem, length, scratch);
/* Gain computation, TIA/IS-127 5.9.4-2 */
for (i = 0, sum1 = 0, sum2 = 0; i < length; i++) {
sum1 += in[i] * in[i];
sum2 += scratch[i] * scratch[i];
}
gain = sum2 ? sqrt(sum1 / sum2) : 1.0;
for (i = 0; i < length; i++)
temp[i] *= gain;
/* Short term postfilter */
synthesis_filter(temp, wcoef2, e->postfilter_iir, length, out);
memmove(e->postfilter_residual,
e->postfilter_residual + length, ACB_SIZE * sizeof(float));
}
static void frame_erasure(EVRCContext *e, float *samples)
{
float ilspf[FILTER_ORDER], ilpc[FILTER_ORDER], idelay[NB_SUBFRAMES],
tmp[SUBFRAME_SIZE + 6], f;
int i, j;
for (i = 0; i < FILTER_ORDER; i++) {
if (e->bitrate != RATE_QUANT)
e->lspf[i] = e->prev_lspf[i] * 0.875 + 0.125 * (i + 1) * 0.048;
else
e->lspf[i] = e->prev_lspf[i];
}
if (e->prev_error_flag)
e->avg_acb_gain *= 0.75;
if (e->bitrate == RATE_FULL)
memcpy(e->pitch_back, e->pitch, ACB_SIZE * sizeof(float));
if (e->last_valid_bitrate == RATE_QUANT)
e->bitrate = RATE_QUANT;
else
e->bitrate = RATE_FULL;
if (e->bitrate == RATE_FULL || e->bitrate == RATE_HALF) {
e->pitch_delay = e->prev_pitch_delay;
} else {
float sum = 0;
idelay[0] = idelay[1] = idelay[2] = MIN_DELAY;
for (i = 0; i < NB_SUBFRAMES; i++)
sum += evrc_energy_quant[e->prev_energy_gain][i];
sum /= (float) NB_SUBFRAMES;
sum = pow(10, sum);
for (i = 0; i < NB_SUBFRAMES; i++)
e->energy_vector[i] = sum;
}
if (fabs(e->pitch_delay - e->prev_pitch_delay) > 15)
e->prev_pitch_delay = e->pitch_delay;
for (i = 0; i < NB_SUBFRAMES; i++) {
int subframe_size = subframe_sizes[i];
int pitch_lag;
interpolate_lsp(ilspf, e->lspf, e->prev_lspf, i);
if (e->bitrate != RATE_QUANT) {
if (e->avg_acb_gain < 0.3) {
idelay[0] = estimation_delay[i];
idelay[1] = estimation_delay[i + 1];
idelay[2] = estimation_delay[i + 2];
} else {
interpolate_delay(idelay, e->pitch_delay, e->prev_pitch_delay, i);
}
}
pitch_lag = lrintf((idelay[1] + idelay[0]) / 2.0);
decode_predictor_coeffs(ilspf, ilpc);
if (e->bitrate != RATE_QUANT) {
acb_excitation(e, e->pitch + ACB_SIZE,
e->avg_acb_gain, idelay, subframe_size);
for (j = 0; j < subframe_size; j++)
e->pitch[ACB_SIZE + j] *= e->fade_scale;
e->fade_scale = FFMAX(e->fade_scale - 0.05, 0.0);
} else {
for (j = 0; j < subframe_size; j++)
e->pitch[ACB_SIZE + j] = e->energy_vector[i];
}
memmove(e->pitch, e->pitch + subframe_size, ACB_SIZE * sizeof(float));
if (e->bitrate != RATE_QUANT && e->avg_acb_gain < 0.4) {
f = 0.1 * e->avg_fcb_gain;
for (j = 0; j < subframe_size; j++)
e->pitch[ACB_SIZE + j] += f;
} else if (e->bitrate == RATE_QUANT) {
for (j = 0; j < subframe_size; j++)
e->pitch[ACB_SIZE + j] = e->energy_vector[i];
}
synthesis_filter(e->pitch + ACB_SIZE, ilpc,
e->synthesis, subframe_size, tmp);
postfilter(e, tmp, ilpc, samples, pitch_lag,
&postfilter_coeffs[e->bitrate], subframe_size);
samples += subframe_size;
}
}
static int evrc_decode_frame(AVCodecContext *avctx, void *data,
int *got_frame_ptr, AVPacket *avpkt)
{
const uint8_t *buf = avpkt->data;
AVFrame *frame = data;
EVRCContext *e = avctx->priv_data;
int buf_size = avpkt->size;
float ilspf[FILTER_ORDER], ilpc[FILTER_ORDER], idelay[NB_SUBFRAMES];
float *samples;
int i, j, ret, error_flag = 0;
frame->nb_samples = 160;
if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
return ret;
samples = (float *)frame->data[0];
if ((e->bitrate = determine_bitrate(avctx, &buf_size, &buf)) == RATE_ERRS) {
warn_insufficient_frame_quality(avctx, "bitrate cannot be determined.");
goto erasure;
}
if (e->bitrate <= SILENCE || e->bitrate == RATE_QUARTER)
goto erasure;
if (e->bitrate == RATE_QUANT && e->last_valid_bitrate == RATE_FULL
&& !e->prev_error_flag)
goto erasure;
if ((ret = init_get_bits8(&e->gb, buf, buf_size)) < 0)
return ret;
memset(&e->frame, 0, sizeof(EVRCAFrame));
unpack_frame(e);
if (e->bitrate != RATE_QUANT) {
uint8_t *p = (uint8_t *) &e->frame;
for (i = 0; i < sizeof(EVRCAFrame); i++) {
if (p[i])
break;
}
if (i == sizeof(EVRCAFrame))
goto erasure;
} else if (e->frame.lsp[0] == 0xf &&
e->frame.lsp[1] == 0xf &&
e->frame.energy_gain == 0xff) {
goto erasure;
}
if (decode_lspf(e) < 0)
goto erasure;
if (e->bitrate == RATE_FULL || e->bitrate == RATE_HALF) {
/* Pitch delay parameter checking as per TIA/IS-127 5.1.5.1 */
if (e->frame.pitch_delay > MAX_DELAY - MIN_DELAY)
goto erasure;
e->pitch_delay = e->frame.pitch_delay + MIN_DELAY;
/* Delay diff parameter checking as per TIA/IS-127 5.1.5.2 */
if (e->frame.delay_diff) {
int p = e->pitch_delay - e->frame.delay_diff + 16;
if (p < MIN_DELAY || p > MAX_DELAY)
goto erasure;
}
/* Delay contour reconstruction as per TIA/IS-127 5.2.2.2 */
if (e->frame.delay_diff &&
e->bitrate == RATE_FULL && e->prev_error_flag) {
float delay;
memcpy(e->pitch, e->pitch_back, ACB_SIZE * sizeof(float));
delay = e->prev_pitch_delay;
e->prev_pitch_delay = delay - e->frame.delay_diff + 16.0;
if (fabs(e->pitch_delay - delay) > 15)
delay = e->pitch_delay;
for (i = 0; i < NB_SUBFRAMES; i++) {
int subframe_size = subframe_sizes[i];
interpolate_delay(idelay, delay, e->prev_pitch_delay, i);
acb_excitation(e, e->pitch + ACB_SIZE, e->avg_acb_gain, idelay, subframe_size);
memmove(e->pitch, e->pitch + subframe_size, ACB_SIZE * sizeof(float));
}
}
/* Smoothing of the decoded delay as per TIA/IS-127 5.2.2.5 */
if (fabs(e->pitch_delay - e->prev_pitch_delay) > 15)
e->prev_pitch_delay = e->pitch_delay;
e->avg_acb_gain = e->avg_fcb_gain = 0.0;
} else {
idelay[0] = idelay[1] = idelay[2] = MIN_DELAY;
/* Decode frame energy vectors as per TIA/IS-127 5.7.2 */
for (i = 0; i < NB_SUBFRAMES; i++)
e->energy_vector[i] = pow(10, evrc_energy_quant[e->frame.energy_gain][i]);
e->prev_energy_gain = e->frame.energy_gain;
}
for (i = 0; i < NB_SUBFRAMES; i++) {
float tmp[SUBFRAME_SIZE + 6] = { 0 };
int subframe_size = subframe_sizes[i];
int pitch_lag;
interpolate_lsp(ilspf, e->lspf, e->prev_lspf, i);
if (e->bitrate != RATE_QUANT)
interpolate_delay(idelay, e->pitch_delay, e->prev_pitch_delay, i);
pitch_lag = lrintf((idelay[1] + idelay[0]) / 2.0);
decode_predictor_coeffs(ilspf, ilpc);
/* Bandwidth expansion as per TIA/IS-127 5.2.3.3 */
if (e->frame.lpc_flag && e->prev_error_flag)
bandwidth_expansion(ilpc, ilpc, 0.75);
if (e->bitrate != RATE_QUANT) {
float acb_sum, f;
f = exp((e->bitrate == RATE_HALF ? 0.5 : 0.25)
* (e->frame.fcb_gain[i] + 1));
acb_sum = pitch_gain_vq[e->frame.acb_gain[i]];
e->avg_acb_gain += acb_sum / NB_SUBFRAMES;
e->avg_fcb_gain += f / NB_SUBFRAMES;
acb_excitation(e, e->pitch + ACB_SIZE,
acb_sum, idelay, subframe_size);
fcb_excitation(e, e->frame.fcb_shape[i], tmp,
acb_sum, pitch_lag, subframe_size);
/* Total excitation generation as per TIA/IS-127 5.2.3.9 */
for (j = 0; j < subframe_size; j++)
e->pitch[ACB_SIZE + j] += f * tmp[j];
e->fade_scale = FFMIN(e->fade_scale + 0.2, 1.0);
} else {
for (j = 0; j < subframe_size; j++)
e->pitch[ACB_SIZE + j] = e->energy_vector[i];
}
memmove(e->pitch, e->pitch + subframe_size, ACB_SIZE * sizeof(float));
synthesis_filter(e->pitch + ACB_SIZE, ilpc,
e->synthesis, subframe_size,
e->postfilter ? tmp : samples);
if (e->postfilter)
postfilter(e, tmp, ilpc, samples, pitch_lag,
&postfilter_coeffs[e->bitrate], subframe_size);
samples += subframe_size;
}
if (error_flag) {
erasure:
error_flag = 1;
av_log(avctx, AV_LOG_WARNING, "frame erasure\n");
frame_erasure(e, samples);
}
memcpy(e->prev_lspf, e->lspf, sizeof(e->prev_lspf));
e->prev_error_flag = error_flag;
e->last_valid_bitrate = e->bitrate;
if (e->bitrate != RATE_QUANT)
e->prev_pitch_delay = e->pitch_delay;
samples = (float *)frame->data[0];
for (i = 0; i < 160; i++)
samples[i] /= 32768;
*got_frame_ptr = 1;
return avpkt->size;
}
#define OFFSET(x) offsetof(EVRCContext, x)
#define AD AV_OPT_FLAG_AUDIO_PARAM | AV_OPT_FLAG_DECODING_PARAM
static const AVOption options[] = {
{ "postfilter", "enable postfilter", OFFSET(postfilter), AV_OPT_TYPE_BOOL, {.i64 = 1}, 0, 1, AD },
{ NULL }
};
static const AVClass evrcdec_class = {
.class_name = "evrc",
.item_name = av_default_item_name,
.option = options,
.version = LIBAVUTIL_VERSION_INT,
};
AVCodec ff_evrc_decoder = {
.name = "evrc",
.long_name = NULL_IF_CONFIG_SMALL("EVRC (Enhanced Variable Rate Codec)"),
.type = AVMEDIA_TYPE_AUDIO,
.id = AV_CODEC_ID_EVRC,
.init = evrc_decode_init,
.decode = evrc_decode_frame,
.capabilities = AV_CODEC_CAP_DR1,
.priv_data_size = sizeof(EVRCContext),
.priv_class = &evrcdec_class,
};
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