diff options
Diffstat (limited to 'codec/synth.c')
| -rw-r--r-- | codec/synth.c | 381 |
1 files changed, 381 insertions, 0 deletions
diff --git a/codec/synth.c b/codec/synth.c new file mode 100644 index 0000000..69ce9ff --- /dev/null +++ b/codec/synth.c @@ -0,0 +1,381 @@ +/* Iridium AMBE vocoder - Speech synthesis */ + +/* (C) 2015 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 Iridium AMBE vocoder speech synthesis + */ + +#include <stdio.h> +#include <stdint.h> +#include <math.h> +#include <string.h> + +#include "private.h" + +/*! \brief Synthesis window (49 samples overlap) */ +static const float ws[] = { + 0.00f, 0.02f, + 0.04f, 0.06f, 0.08f, 0.10f, 0.12f, 0.14f, 0.16f, 0.18f, + 0.20f, 0.22f, 0.24f, 0.26f, 0.28f, 0.30f, 0.32f, 0.34f, + 0.36f, 0.38f, 0.40f, 0.42f, 0.44f, 0.46f, 0.48f, 0.50f, + 0.52f, 0.54f, 0.56f, 0.58f, 0.60f, 0.62f, 0.64f, 0.66f, + 0.68f, 0.70f, 0.72f, 0.74f, 0.76f, 0.78f, 0.80f, 0.82f, + 0.84f, 0.86f, 0.88f, 0.90f, 0.92f, 0.94f, 0.96f, 0.98f, + 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, + 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, + 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, + 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, + 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, + 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, + 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, + 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, + 1.00f, 1.00f, 1.00f, + 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, + 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, + 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, + 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, + 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, + 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, + 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, + 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, 1.00f, + 0.98f, 0.96f, 0.94f, 0.92f, 0.90f, 0.88f, 0.86f, 0.84f, + 0.82f, 0.80f, 0.78f, 0.76f, 0.74f, 0.72f, 0.70f, 0.68f, + 0.66f, 0.64f, 0.62f, 0.60f, 0.58f, 0.56f, 0.54f, 0.52f, + 0.50f, 0.48f, 0.46f, 0.44f, 0.42f, 0.40f, 0.38f, 0.36f, + 0.34f, 0.32f, 0.30f, 0.28f, 0.26f, 0.24f, 0.22f, 0.20f, + 0.18f, 0.16f, 0.14f, 0.12f, 0.10f, 0.08f, 0.06f, 0.04f, + 0.02f, 0.00f, +}; + +/*! \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 +ir77_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 (180 samples) + * \param[in] sf Expanded subframe data + */ +static void +ir77_ambe_synth_unvoiced(struct ir77_ambe_synth *synth, float *suv, + struct ir77_ambe_subframe *sf) +{ + uint16_t u[231]; + float uw[231]; + float Uwi[129], Uwq[129]; + int i, al, bl, l; + + /* Generate the white noise sequence and window it with ws */ + ir77_ambe_gen_random(u, synth->u_prev, 231); + synth->u_prev = u[179]; + + for (i=0; i<231; i++) + uw[i] = (float)u[i] * ws[i]; + + /* Compute the DFT */ + ir77_ambe_fdft_fc(Uwi, Uwq, uw, 256, 231); + + /* Apply the spectral magnitude */ + bl = ceilf(256.0f / (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(256.0f / (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<=128; i++) { + Uwi[i] = 0.0f; + Uwq[i] = 0.0f; + } + + /* Get time-domain samples via iDFT */ + ir77_ambe_idft_cf(uw, Uwi, Uwq, 256, 231); + + /* Weighted Overlap And Add */ + for (i=0; i<66; i++) { + suv[i] = synth->uw_prev[i + 115]; + } + + for (i=66; i<115; i++) { + suv[i] = (ws[i + 115] * synth->uw_prev[i + 115] + ws[i - 65] * uw[i - 65]) + / (ws[i + 115] * ws[i + 115] + ws[i - 65] * ws[i - 65]); + } + + for (i=115; i<180; i++) { + suv[i] = uw[i - 65]; + } + + memcpy(synth->uw_prev, uw, sizeof(float) * 231); +} + +/*! \brief Perform voiced synthesis + * \param[in] synth Synthesizer state structure + * \param[out] sv Result buffer (180 samples) + * \param[in] sf Expanded subframe data for current subframe + * \param[in] sf_prev Expanded subframe data for prevous subframe + */ +static void +ir77_ambe_synth_voiced(struct ir77_ambe_synth *synth, float *sv, + struct ir77_ambe_subframe *sf, + struct ir77_ambe_subframe *sf_prev) +{ + int i, l, L_max, L_uv; + + /* Pre-clear */ + memset(sv, 0x00, sizeof(float) * 180); + + /* 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) * 90.0f, 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) / 180.0f; + float Dpl = phi_cur - phi_prev - (w_cur + w_prev) * 90.0f; + float Dwl = (Dpl - 2 * M_PIf * floorf((Dpl + M_PIf) / (2 * M_PIf))) / 180.0f; + float THa = w_prev + Dwl; + float THb = (w_cur - w_prev) / 360.0f; + + for (i=0; i<180; 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=66; i<180; i++) + sv[i] += ws[i-65] * Ml_cur * cosf_fast(phi_cur + w_cur * (i - 180)); + } + + /* Coarse transition: Previous frame (if voiced) */ + if (!fine && Vl_prev) + { + for (i=0; i<115; i++) + sv[i] += ws[i+115] * 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 +ir77_ambe_synth_init(struct ir77_ambe_synth *synth) +{ + memset(synth, 0x00, sizeof(struct ir77_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 +ir77_ambe_synth_enhance(struct ir77_ambe_synth *synth, + struct ir77_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 (180 samples) + * \param[in] sf Expanded subframe data for current subframe + * \param[in] sf_prev Expanded subframe data for prevous subframe + */ +void +ir77_ambe_synth_audio(struct ir77_ambe_synth *synth, int16_t *audio, + struct ir77_ambe_subframe *sf, + struct ir77_ambe_subframe *sf_prev) +{ + float suv[180], sv[180]; + int i; + + ir77_ambe_synth_unvoiced(synth, suv, sf); + ir77_ambe_synth_voiced(synth, sv, sf, sf_prev); + for (i=0; i<180; i++) + audio[i] = (int16_t)((suv[i] + 2.0f * sv[i]) * 4.0f); +} + +/*! @} */ |