286 lines
8.5 KiB
C
286 lines
8.5 KiB
C
/*---------------------------------------------------------------------------*\
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FILE........: interp.c
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AUTHOR......: David Rowe
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DATE CREATED: 9/10/09
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Interpolation of 20ms frames to 10ms frames.
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\*---------------------------------------------------------------------------*/
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/*
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Copyright (C) 2009 David Rowe
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All rights reserved.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License version 2.1, as
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published by the Free Software Foundation. This program is
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distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
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License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program; if not, see <http://www.gnu.org/licenses/>.
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*/
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#include <assert.h>
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#include <math.h>
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#include <string.h>
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#include <stdio.h>
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#include "defines.h"
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#include "interp.h"
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#include "lsp.h"
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#include "quantise.h"
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float sample_log_amp(MODEL *model, float w);
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/*---------------------------------------------------------------------------*\
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FUNCTION....: interp()
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AUTHOR......: David Rowe
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DATE CREATED: 22/8/10
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Given two frames decribed by model parameters 20ms apart, determines
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the model parameters of the 10ms frame between them. Assumes
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voicing is available for middle (interpolated) frame. Outputs are
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amplitudes and Wo for the interpolated frame.
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This version can interpolate the amplitudes between two frames of
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different Wo and L.
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This version works by log linear interpolation, but listening tests
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showed it creates problems in background noise, e.g. hts2a and mmt1.
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When this function is used (--dec mode) bg noise appears to be
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amplitude modulated, and gets louder. The interp_lsp() function
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below seems to do a better job.
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\*---------------------------------------------------------------------------*/
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void interpolate(
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MODEL *interp, /* interpolated model params */
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MODEL *prev, /* previous frames model params */
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MODEL *next /* next frames model params */
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)
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{
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int l;
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float w,log_amp;
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/* Wo depends on voicing of this and adjacent frames */
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if (interp->voiced) {
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if (prev->voiced && next->voiced)
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interp->Wo = (prev->Wo + next->Wo)/2.0;
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if (!prev->voiced && next->voiced)
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interp->Wo = next->Wo;
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if (prev->voiced && !next->voiced)
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interp->Wo = prev->Wo;
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}
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else {
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interp->Wo = TWO_PI/P_MAX;
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}
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interp->L = PI/interp->Wo;
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/* Interpolate amplitudes using linear interpolation in log domain */
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for(l=1; l<=interp->L; l++) {
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w = l*interp->Wo;
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log_amp = (sample_log_amp(prev, w) + sample_log_amp(next, w))/2.0;
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interp->A[l] = pow(10.0, log_amp);
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}
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}
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/*---------------------------------------------------------------------------*\
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FUNCTION....: sample_log_amp()
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AUTHOR......: David Rowe
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DATE CREATED: 22/8/10
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Samples the amplitude envelope at an arbitrary frequency w. Uses
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linear interpolation in the log domain to sample between harmonic
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amplitudes.
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\*---------------------------------------------------------------------------*/
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float sample_log_amp(MODEL *model, float w)
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{
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int m;
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float f, log_amp;
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assert(w > 0.0); assert (w <= PI);
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m = floor(w/model->Wo + 0.5);
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f = (w - m*model->Wo)/w;
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assert(f <= 1.0);
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if (m < 1) {
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log_amp = f*log10(model->A[1] + 1E-6);
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}
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else if ((m+1) > model->L) {
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log_amp = (1.0-f)*log10(model->A[model->L] + 1E-6);
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}
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else {
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log_amp = (1.0-f)*log10(model->A[m] + 1E-6) +
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f*log10(model->A[m+1] + 1E-6);
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}
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return log_amp;
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}
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/*---------------------------------------------------------------------------*\
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FUNCTION....: interp_lsp()
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AUTHOR......: David Rowe
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DATE CREATED: 10 Nov 2010
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Given two frames decribed by model parameters 20ms apart, determines
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the model parameters of the 10ms frame between them. Assumes
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voicing is available for middle (interpolated) frame. Outputs are
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amplitudes and Wo for the interpolated frame.
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This version uses interpolation of LSPs, seems to do a better job
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with bg noise.
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\*---------------------------------------------------------------------------*/
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void interpolate_lsp(
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kiss_fft_cfg fft_fwd_cfg,
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MODEL *interp, /* interpolated model params */
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MODEL *prev, /* previous frames model params */
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MODEL *next, /* next frames model params */
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float *prev_lsps, /* previous frames LSPs */
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float prev_e, /* previous frames LPC energy */
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float *next_lsps, /* next frames LSPs */
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float next_e, /* next frames LPC energy */
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float *ak_interp, /* interpolated aks for this frame */
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float *lsps_interp/* interpolated lsps for this frame */
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)
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{
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int i;
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float e;
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float snr;
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/* trap corner case where V est is probably wrong */
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if (interp->voiced && !prev->voiced && !next->voiced) {
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interp->voiced = 0;
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}
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/* Wo depends on voicing of this and adjacent frames */
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if (interp->voiced) {
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if (prev->voiced && next->voiced)
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interp->Wo = (prev->Wo + next->Wo)/2.0;
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if (!prev->voiced && next->voiced)
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interp->Wo = next->Wo;
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if (prev->voiced && !next->voiced)
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interp->Wo = prev->Wo;
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}
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else {
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interp->Wo = TWO_PI/P_MAX;
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}
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interp->L = PI/interp->Wo;
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//printf(" interp: prev_v: %d next_v: %d prev_Wo: %f next_Wo: %f\n",
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// prev->voiced, next->voiced, prev->Wo, next->Wo);
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//printf(" interp: Wo: %1.5f L: %d\n", interp->Wo, interp->L);
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/* interpolate LSPs */
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for(i=0; i<LPC_ORD; i++) {
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lsps_interp[i] = (prev_lsps[i] + next_lsps[i])/2.0;
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}
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/* Interpolate LPC energy in log domain */
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e = pow(10.0, (log10(prev_e) + log10(next_e))/2.0);
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//printf(" interp: e: %f\n", e);
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/* convert back to amplitudes */
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lsp_to_lpc(lsps_interp, ak_interp, LPC_ORD);
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aks_to_M2(fft_fwd_cfg, ak_interp, LPC_ORD, interp, e, &snr, 0, 0, 1, 1, LPCPF_BETA, LPCPF_GAMMA);
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//printf(" interp: ak[1]: %f A[1] %f\n", ak_interp[1], interp->A[1]);
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}
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/*---------------------------------------------------------------------------*\
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FUNCTION....: interp_Wo()
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AUTHOR......: David Rowe
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DATE CREATED: 22 May 2012
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Interpolates centre 10ms sample of Wo and L samples given two
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samples 20ms apart. Assumes voicing is available for centre
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(interpolated) frame.
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\*---------------------------------------------------------------------------*/
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void interp_Wo(
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MODEL *interp, /* interpolated model params */
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MODEL *prev, /* previous frames model params */
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MODEL *next /* next frames model params */
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)
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{
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/* trap corner case where voicing est is probably wrong */
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if (interp->voiced && !prev->voiced && !next->voiced) {
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interp->voiced = 0;
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}
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/* Wo depends on voicing of this and adjacent frames */
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if (interp->voiced) {
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if (prev->voiced && next->voiced)
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interp->Wo = (prev->Wo + next->Wo)/2.0;
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if (!prev->voiced && next->voiced)
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interp->Wo = next->Wo;
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if (prev->voiced && !next->voiced)
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interp->Wo = prev->Wo;
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}
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else {
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interp->Wo = TWO_PI/P_MAX;
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}
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interp->L = PI/interp->Wo;
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}
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/*---------------------------------------------------------------------------*\
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FUNCTION....: interp_energy()
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AUTHOR......: David Rowe
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DATE CREATED: 22 May 2012
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Interpolates centre 10ms sample of energy given two samples 20ms
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apart.
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\*---------------------------------------------------------------------------*/
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float interp_energy(float prev_e, float next_e)
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{
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return pow(10.0, (log10(prev_e) + log10(next_e))/2.0);
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}
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/*---------------------------------------------------------------------------*\
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FUNCTION....: interpolate_lsp_ver2()
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AUTHOR......: David Rowe
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DATE CREATED: 22 May 2012
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Weighted interpolation of LSPs.
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\*---------------------------------------------------------------------------*/
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void interpolate_lsp_ver2(float interp[], float prev[], float next[], float weight)
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{
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int i;
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for(i=0; i<LPC_ORD; i++)
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interp[i] = (1.0 - weight)*prev[i] + weight*next[i];
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}
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