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osmo-gmr/src/codec/synth.c

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/* GMR-1 AMBE vocoder - Speech synthesis */
/* (C) 2011-2019 by Sylvain Munaut <tnt@246tNt.com>
* All Rights Reserved
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* This program 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 Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/*! \addtogroup codec_private
* @{
*/
/*! \file codec/synth.c
* \brief Osmocom GMR-1 AMBE vocoder speech synthesis
*/
#include <stdio.h>
#include <stdint.h>
#include <math.h>
#include <string.h>
#include "private.h"
/*! \brief Synthesis window (39 samples overlap) */
static const float ws[] = {
0.000f, 0.025f, 0.050f, 0.075f, 0.100f, 0.125f, 0.150f, 0.175f,
0.200f, 0.225f, 0.250f, 0.275f, 0.300f, 0.325f, 0.350f, 0.375f,
0.400f, 0.425f, 0.450f, 0.475f, 0.500f, 0.525f, 0.550f, 0.575f,
0.600f, 0.625f, 0.650f, 0.675f, 0.700f, 0.725f, 0.750f, 0.775f,
0.800f, 0.825f, 0.850f, 0.875f, 0.900f, 0.925f, 0.950f, 0.975f,
1.000f, 1.000f, 1.000f, 1.000f, 1.000f, 1.000f, 1.000f, 1.000f,
1.000f, 1.000f, 1.000f, 1.000f, 1.000f, 1.000f, 1.000f, 1.000f,
1.000f, 1.000f, 1.000f, 1.000f,
1.000f,
1.000f, 1.000f, 1.000f, 1.000f,
1.000f, 1.000f, 1.000f, 1.000f, 1.000f, 1.000f, 1.000f, 1.000f,
1.000f, 1.000f, 1.000f, 1.000f, 1.000f, 1.000f, 1.000f, 1.000f,
0.975f, 0.950f, 0.925f, 0.900f, 0.875f, 0.850f, 0.825f, 0.800f,
0.775f, 0.750f, 0.725f, 0.700f, 0.675f, 0.650f, 0.625f, 0.600f,
0.575f, 0.550f, 0.525f, 0.500f, 0.475f, 0.450f, 0.425f, 0.400f,
0.375f, 0.350f, 0.325f, 0.300f, 0.275f, 0.250f, 0.225f, 0.200f,
0.175f, 0.150f, 0.125f, 0.100f, 0.075f, 0.050f, 0.025f, 0.000f,
};
/*! \brief Pitch refinement window */
static const float wr[] = {
0.014873f, 0.019270f, 0.024182f, 0.029633f, 0.035694f, 0.042353f,
0.049618f, 0.057539f, 0.066135f, 0.075386f, 0.085322f, 0.095993f,
0.107350f, 0.119398f, 0.132219f, 0.145736f, 0.159947f, 0.174903f,
0.190559f, 0.206884f, 0.223901f, 0.241592f, 0.259901f, 0.278822f,
0.298359f, 0.318434f, 0.339018f, 0.360127f, 0.381668f, 0.403604f,
0.425920f, 0.448547f, 0.471431f, 0.494535f, 0.517800f, 0.541163f,
0.564575f, 0.587971f, 0.611295f, 0.634490f, 0.657474f, 0.680203f,
0.702622f, 0.724637f, 0.746204f, 0.767276f, 0.787766f, 0.807607f,
0.826778f, 0.845205f, 0.862786f, 0.879533f, 0.895400f, 0.910234f,
0.924090f, 0.936931f, 0.948628f, 0.959200f, 0.968647f, 0.976876f,
0.983859f, 0.989640f, 0.994168f, 0.997358f, 0.999304f,
1.000000f,
0.999304f, 0.997358f, 0.994168f, 0.989640f, 0.983859f,
0.976876f, 0.968647f, 0.959200f, 0.948628f, 0.936931f, 0.924090f,
0.910234f, 0.895400f, 0.879533f, 0.862786f, 0.845205f, 0.826778f,
0.807607f, 0.787766f, 0.767276f, 0.746204f, 0.724637f, 0.702622f,
0.680203f, 0.657474f, 0.634490f, 0.611295f, 0.587971f, 0.564575f,
0.541163f, 0.517800f, 0.494535f, 0.471431f, 0.448547f, 0.425920f,
0.403604f, 0.381668f, 0.360127f, 0.339018f, 0.318434f, 0.298359f,
0.278822f, 0.259901f, 0.241592f, 0.223901f, 0.206884f, 0.190559f,
0.174903f, 0.159947f, 0.145736f, 0.132219f, 0.119398f, 0.107350f,
0.095993f, 0.085322f, 0.075386f, 0.066135f, 0.057539f, 0.049618f,
0.042353f, 0.035694f, 0.029633f, 0.024182f, 0.019270f, 0.014873f,
};
/*! \brief Random phase increment (precomputed) */
static const float rho[] = {
3.002978f, -0.385743f, -1.804058f, 0.708389f, 3.080091f, 0.234237f,
-2.601564f, 2.564900f, 0.101063f, -0.241570f, -2.283176f, 0.460491f,
-1.611275f, 2.258339f, -2.055267f, 1.733923f, 2.517236f, -1.766211f,
0.897032f, -2.360999f, -0.280836f, -2.714514f, 2.100092f, 2.300326f,
-1.158767f, -2.044268f, -2.668387f, -2.578737f, 0.185036f, 1.551429f,
2.726814f, 2.655614f, 3.046857f, 0.834348f, -0.513595f, 1.466037f,
0.691121f, 0.127319f, -2.034924f, -1.070655f, 0.456588f, -2.278682f,
1.229021f, -2.139595f, -0.119750f, -0.301534f, 0.029391f, 0.068775f,
0.520336f, 2.339119f, -0.808328f, 1.332154f, 2.929768f, -0.338316f,
0.022767f, -1.063795f,
};
/*! \brief Generates random sequence of uint16_t according to spec
* \param[out] u_seq Result buffer
* \param[in] u_prev Last 'u' value of where to resume from
* \param[in] n Number of items to generate
*/
static void
ambe_gen_random(uint16_t *u_seq, uint16_t u_prev, int n)
{
uint32_t u = u_prev;
int i;
for (i=0; i<n; i++) {
u = (u * 171 + 11213) % 53125;
u_seq[i] = u;
}
}
/*! \brief Perform unvoiced synthesis
* \param[in] synth Synthesizer state structure
* \param[out] suv Result buffer (80 samples)
* \param[in] sf Expanded subframe data
*/
static void
ambe_synth_unvoiced(struct ambe_synth *synth, float *suv, struct ambe_subframe *sf)
{
uint16_t u[121];
float uw[121];
float Uwi[65], Uwq[65];
int i, al, bl, l;
/* Generate the white noise sequence and window it with ws */
ambe_gen_random(u, synth->u_prev, 121);
synth->u_prev = u[79];
for (i=0; i<121; i++)
uw[i] = (float)u[i] * ws[i];
/* Compute the DFT */
ambe_fdft_fc(Uwi, Uwq, uw, 128, 121);
/* Apply the spectral magnitude */
bl = ceilf(128.0f / (2 * M_PIf) * (.5f) * sf->w0);
for (i=0; i<bl; i++) {
Uwi[i] = 0.0f;
Uwq[i] = 0.0f;
}
for (l=0; l<sf->L; l++)
{
float ampl;
/* Edges */
al = bl;
bl = ceilf(128.0f / (2 * M_PIf) * (l + 1.5f) * sf->w0);
/* Compute factor */
ampl = 0.0f;
for (i=al; i<bl; i++) {
ampl += Uwi[i] * Uwi[i] + Uwq[i] * Uwq[i];
}
ampl = 76.89f * sf->Ml[l] / sqrtf(ampl / (bl - al));
/* Set magnitude */
for (i=al; i<bl; i++) {
if (sf->Vl[l]) {
Uwi[i] = 0.0f;
Uwq[i] = 0.0f;
} else {
Uwi[i] *= ampl;
Uwq[i] *= ampl;
}
}
}
for (i=bl; i<=64; i++) {
Uwi[i] = 0.0f;
Uwq[i] = 0.0f;
}
/* Get time-domain samples via iDFT */
ambe_idft_cf(uw, Uwi, Uwq, 128, 121);
/* Weighted Overlap And Add */
for (i=0; i<21; i++) {
suv[i] = synth->uw_prev[i + 60];
}
for (i=21; i<60; i++) {
suv[i] = (ws[i + 60] * synth->uw_prev[i + 60] + ws[i - 20] * uw[i - 20])
/ (ws[i + 60] * ws[i + 60] + ws[i - 20] * ws[i - 20]);
}
for (i=60; i<80; i++) {
suv[i] = uw[i - 20];
}
memcpy(synth->uw_prev, uw, sizeof(float) * 121);
}
/*! \brief Perform voiced synthesis
* \param[in] synth Synthesizer state structure
* \param[out] sv Result buffer (80 samples)
* \param[in] sf Expanded subframe data for current subframe
* \param[in] sf_prev Expanded subframe data for prevous subframe
*/
static void
ambe_synth_voiced(struct ambe_synth *synth, float *sv,
struct ambe_subframe *sf, struct ambe_subframe *sf_prev)
{
int i, l, L_max, L_uv;
/* Pre-clear */
memset(sv, 0x00, sizeof(float) * 80);
/* How many subband to process */
L_max = sf_prev->L > sf->L ? sf_prev->L : sf->L;
/* psi update */
L_uv = 0;
for (l=0; l<L_max; l++)
L_uv += sf->Vl[l] ? 0 : 1;
synth->psi1 = remainderf(synth->psi1 + (sf->w0 + sf_prev->w0) * 40.0f, 2 * M_PIf);
/* Scan each band */
for (l=0; l<L_max; l++)
{
int Vl_cur, Vl_prev;
float Ml_cur, Ml_prev;
float phi_cur, phi_prev;
float w_cur, w_prev;
int fine;
/* Handle out-of-bound for Vl and Ml */
Vl_cur = l >= sf->L ? 0 : sf->Vl[l];
Vl_prev = l >= sf_prev->L ? 0 : sf_prev->Vl[l];
Ml_cur = l >= sf->L ? 0.0f : sf->Ml[l];
Ml_prev = l >= sf_prev->L ? 0.0f : sf_prev->Ml[l];
/* Phase and Angular speed */
w_cur = (l+1) * sf->w0;
w_prev = (l+1) * sf_prev->w0;
phi_prev = synth->phi[l];
phi_cur = synth->psi1 * (l+1);
if (l >= (sf->L / 4))
phi_cur += ((float)L_uv / (float)sf->L) * rho[l];
synth->phi[l] = phi_cur;
/* Actual synthesis */
/* Can we do a fine transistion ? */
fine = Vl_cur && Vl_prev && (l < 7) && (fabsf(w_cur - w_prev) < (.1f * w_cur));
/* Fine transition */
if (fine)
{
float Ml_step = (Ml_cur - Ml_prev) / 80.0f;
float Dpl = phi_cur - phi_prev - (w_cur + w_prev) * 40.0f;
float Dwl = (Dpl - 2 * M_PIf * floorf((Dpl + M_PIf) / (2 * M_PIf))) / 80.0f;
float THa = w_prev + Dwl;
float THb = (w_cur - w_prev) / 160.0f;
for (i=0; i<80; i++)
sv[i] += (Ml_prev + i * Ml_step) * cosf_fast(
phi_prev + (THa + THb * i) * i
);
}
/* Coarse transition: Current frame (if voiced) */
if (!fine && Vl_cur)
{
for (i=21; i<80; i++)
sv[i] += ws[i-20] * Ml_cur * cosf_fast(phi_cur + w_cur * (i - 80));
}
/* Coarse transition: Previous frame (if voiced) */
if (!fine && Vl_prev)
{
for (i=0; i<60; i++)
sv[i] += ws[i+60] * Ml_prev * cosf_fast(phi_prev + w_prev * i);
}
}
/* Still need to update phi for the rest of the bands */
for (l=L_max; l<56; l++)
synth->phi[l] = (synth->psi1 * (l+1)) + (((float)L_uv / (float)sf->L) * rho[l]);
}
/*! \brief Initialized Synthesizer state
* \param[out] synth The structure to reset
*/
void
ambe_synth_init(struct ambe_synth *synth)
{
memset(synth, 0x00, sizeof(struct ambe_synth));
synth->u_prev = 3147;
}
/*! \brief Apply the spectral magnitude enhancement on the subframe
* \param[in] synth Synthesizer state structure
* \param[in] sf Expanded subframe data for subframe to enhance
*/
void
ambe_synth_enhance(struct ambe_synth *synth, struct ambe_subframe *sf)
{
float rm0, rm1;
float k1, k2, k3;
float gamma;
int l;
/* Compute RM0 and RM1 */
rm0 = 0.0f;
rm1 = 0.0f;
for (l=0; l<sf->L; l++)
{
float sq = sf->Ml[l] * sf->Ml[l];
rm0 += sq;
rm1 += sq * cosf_fast(sf->w0 * (l+1));
}
/* Pre compute some constants */
k1 = 0.96f * M_PIf / (sf->w0 * rm0 * (rm0 * rm0 - rm1 * rm1));
k2 = rm0 * rm0 + rm1 * rm1;
k3 = 2.0f * rm0 * rm1;
/* Apply to the amplitudes */
gamma = 0.0f;
for (l=0; l<sf->L; l++)
{
float w;
if ( (l+1)*8 <= sf->L ) {
w = 1.0f;
} else {
w = sqrtf(sf->Ml[l]) * powf(
k1 * (k2 - k3 * cosf_fast(sf->w0 * (l+1))),
0.25f
);
if (w > 1.2f)
w = 1.2f;
else if (w < 0.5f)
w = 0.5f;
}
sf->Ml[l] *= w;
gamma += sf->Ml[l] * sf->Ml[l];
}
/* Compute final gamma and apply it */
gamma = sqrtf(rm0 / gamma);
for (l=0; l<sf->L; l++)
{
sf->Ml[l] *= gamma;
}
/* Update SE */
synth->SE = 0.95f * synth->SE + 0.05f * rm0;
if (synth->SE < 1e4f)
synth->SE = 1e4f;
}
/*! \brief Generate audio for a given subframe
* \param[in] synth Synthesizer state structure
* \param[out] audio Result buffer (80 samples)
* \param[in] sf Expanded subframe data for current subframe
* \param[in] sf_prev Expanded subframe data for prevous subframe
*/
void
ambe_synth_audio(struct ambe_synth *synth, int16_t *audio,
struct ambe_subframe *sf,
struct ambe_subframe *sf_prev)
{
float suv[80], sv[80];
int i;
ambe_synth_unvoiced(synth, suv, sf);
ambe_synth_voiced(synth, sv, sf, sf_prev);
for (i=0; i<80; i++)
audio[i] = (int16_t)((suv[i] + 2.0f * sv[i]) * 4.0f);
}
/*! @} */
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