Linear Predictor: Rearrange things somewhat
The original didn't really handle backwards versus forwards differently, as far as the predictor coefficients should have been, as they probably should have been reversed for a different direction window. This didn't fix my problem, though, but did possibly expose something else to mess with. Signed-off-by: Christopher Snowhill <kode54@gmail.com>
This commit is contained in:
Christopher Snowhill
parent
3274bc9fe7
commit
51e8223078
1 changed files with 153 additions and 164 deletions
243
Audio/ThirdParty/lvqcl/lpc.c
vendored
243
Audio/ThirdParty/lvqcl/lpc.c
vendored
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@ -19,64 +19,7 @@
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#include <stdbool.h>
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#include "lpc.h"
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static void apply_window(float * const data, const size_t data_len);
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static void compute_autocorr(const float * const data, const size_t data_len, double * const autoc, const int m);
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static int compute_lpc(const double * const autoc, double * const lpc, const int lpc_order);
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static void lpc_extrapolate_data(float * const data0, const size_t data_len, const size_t extra, const double * const lpc, const int order, const bool invdir);
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void lpc_extrapolate2(float * const data, const size_t data_len, const int nch, const int lpc_order, const size_t extra_bkwd, const size_t extra_fwd, void ** extrapolate_buffer, size_t * extrapolate_buffer_size)
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{
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const size_t tdata0_size = sizeof(float) * (extra_bkwd + data_len + extra_fwd);
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const size_t autoc_size = sizeof(double) * (lpc_order + 1);
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const size_t lpc_size = sizeof(double) * lpc_order;
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const size_t new_size = tdata0_size + autoc_size + lpc_size;
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if (new_size > *extrapolate_buffer_size)
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{
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*extrapolate_buffer = realloc(*extrapolate_buffer, new_size);
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*extrapolate_buffer_size = new_size;
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}
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float* tdata0 = (float*)(*extrapolate_buffer); // for 1 channel only
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float* const tdata = tdata0 + extra_bkwd; // for 1 channel only
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double* autoc = (double*)(*extrapolate_buffer + tdata0_size);
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double* lpc = (double*)(*extrapolate_buffer + tdata0_size + autoc_size);
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int max_order;
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for(int c = 0; c < nch; c++)
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{
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for (int i = -(int)extra_bkwd; i < (int)(data_len+extra_fwd); i++) { tdata[i] = 0; } // should be removed after debugging etc
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for (int i = 0; i < (int)data_len; i++)
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tdata[i] = data[i*nch + c];
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apply_window(tdata, data_len);
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compute_autocorr(tdata, data_len, autoc, lpc_order);
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max_order = compute_lpc(autoc, lpc, lpc_order);
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// restore after apply_window
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for (int i = 0; i < (int)data_len; i++)
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tdata[i] = data[i*nch + c];
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if (extra_fwd)
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{
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lpc_extrapolate_data(tdata, data_len, extra_fwd, lpc, max_order, false);
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for (size_t i = data_len; i < (data_len+extra_fwd); i++)
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data[i*nch + c] = tdata[i];
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}
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if (extra_bkwd)
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{
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lpc_extrapolate_data(tdata, data_len, extra_bkwd, lpc, max_order, true);
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for (int i = -(int)extra_bkwd; i < 0; i++)
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data[i*nch + c] = tdata[i];
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}
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}
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}
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static void apply_window(float * const data, const size_t data_len)
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{
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static void apply_window(float *const data, const size_t data_len) {
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#if 0
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if (0) // subtract the mean
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{
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@ -93,112 +36,158 @@ static void apply_window(float * const data, const size_t data_len)
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if(1) // Welch window
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{
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const float n2 = (data_len + 1) / 2.0f;
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for(int i = 0; i < (int)data_len; i++)
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{
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for(int i = 0; i < (int)data_len; i++) {
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float k = (i + 1 - n2) / n2;
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data[i] *= 1.0f - k*k;
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data[data_len - 1 - i] *= 1.0f - k * k;
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}
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}
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}
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static void compute_autocorr(const float * const data, const size_t data_len, double * const autoc, const int m)
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{
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static float vorbis_lpc_from_data(float *data, float *lpci, int n, int m, double *aut, double *lpc) {
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double error;
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double epsilon;
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int i, j;
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/* autocorrelation, p+1 lag coefficients */
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j = m + 1;
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// for(j = 0; j <= m; j++)
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while(j--)
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{
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double d = 0;
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for(i = j; i < (int)data_len; i++)
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d += (double)data[i] * data[i-j];
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autoc[j] = d;
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}
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while(j--) {
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double d = 0; /* double needed for accumulator depth */
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for(i = j; i < n; i++) d += (double)data[i] * data[i - j];
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aut[j] = d;
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}
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static int compute_lpc(const double * const autoc, double * const lpc, const int lpc_order)
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{
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int i, j;
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double error, epsilon;
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int max_order = lpc_order;
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/* Generate lpc coefficients from autocorr values */
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error = autoc[0] * (1.+1e-10);
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epsilon = 1e-9*autoc[0] + 1e-10;
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/* set our noise floor to about -100dB */
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error = aut[0] * (1. + 1e-10);
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epsilon = 1e-9 * aut[0] + 1e-10;
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for(i = 0; i < lpc_order; i++)
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{
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if (error < epsilon)
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{
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memset(&lpc[i], 0, (lpc_order-i)*sizeof(lpc[0]));
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max_order = i; break;
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for(i = 0; i < m; i++) {
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double r = -aut[i + 1];
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if(error < epsilon) {
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memset(lpc + i, 0, (m - i) * sizeof(*lpc));
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goto done;
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}
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double r = -autoc[i+1];
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for(j = 0; j < i; j++)
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r -= lpc[j] * autoc[i-j];
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/* Sum up this iteration's reflection coefficient; note that in
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Vorbis we don't save it. If anyone wants to recycle this code
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and needs reflection coefficients, save the results of 'r' from
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each iteration. */
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for(j = 0; j < i; j++) r -= lpc[j] * aut[i - j];
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r /= error;
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/* Update LPC coefficients and total error */
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lpc[i] = r;
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for(j = 0; j < i/2; j++)
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{
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for(j = 0; j < i / 2; j++) {
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double tmp = lpc[j];
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lpc[j] += r * lpc[i - 1 - j];
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lpc[i - 1 - j] += r * tmp;
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}
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if (i&1)
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lpc[j] += lpc[j]*r;
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if(i & 1) lpc[j] += lpc[j] * r;
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error *= 1.0 - r*r;
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error *= 1. - r * r;
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}
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if (1) /* slightly damp the filter */
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done:
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/* slightly damp the filter */
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{
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const double g = 0.999;
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double g = .99;
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double damp = g;
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for(j = 0; j < max_order; j++)
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{
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for(j = 0; j < m; j++) {
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lpc[j] *= damp;
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damp *= g;
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}
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}
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if (max_order == 0) /* in case the signal is constant AND we subtract the mean in apply_window() */
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{
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max_order = 1;
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lpc[0] = -1;
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for(j = 0; j < m; j++) lpci[j] = (float)lpc[j];
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/* we need the error value to know how big an impulse to hit the
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filter with later */
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return error;
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}
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return max_order;
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}
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static void vorbis_lpc_predict(float *coeff, float *prime, int m, float *data, long n, float *work) {
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/* in: coeff[0...m-1] LPC coefficients
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prime[0...m-1] initial values (allocated size of n+m-1)
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out: data[0...n-1] data samples */
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static void lpc_extrapolate_data(float * const data0, const size_t data_len, const size_t extra, const double * const lpc, const int order, const bool invdir)
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{
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int i, j;
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if (invdir == false)
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{
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float* data = data0 + data_len - order;
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for(i = 0; i < (int)extra; i++)
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{
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float sum = 0;
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for(j = 0; j < order; j++)
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sum -= data[i+j] * (float)lpc[order-1-j];
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long i, j, o, p;
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float y;
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if (sum > 10.f) sum = 10.f; else if (sum < -10.f) sum = -10.f; // should be removed after debugging etc
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data[order+i] = sum;
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}
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}
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if(!prime)
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for(i = 0; i < m; i++)
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work[i] = 0.f;
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else
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{
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float* data = data0 - 1 + order;
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for(i = 0; i < (int)extra; i++)
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{
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float sum = 0;
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for(j = 0; j < order; j++)
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sum -= data[-i-j] * (float)lpc[order-1-j];
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for(i = 0; i < m; i++)
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work[i] = prime[i];
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if (sum > 10.f) sum = 10.f; else if (sum < -10.f) sum = -10.f; // should be removed after debugging etc
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data[-order-i] = sum;
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for(i = 0; i < n; i++) {
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y = 0;
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o = i;
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p = m;
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for(j = 0; j < m; j++)
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y -= work[o++] * coeff[--p];
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data[i] = work[o] = y;
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}
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}
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void lpc_extrapolate2(float *const data, const size_t data_len, const int nch, const int lpc_order, const size_t extra_bkwd, const size_t extra_fwd, void **extrapolate_buffer, size_t *extrapolate_buffer_size) {
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const size_t tdata_size = sizeof(float) * (extra_bkwd + data_len + extra_fwd);
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const size_t aut_size = sizeof(double) * (lpc_order + 1);
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const size_t lpc_size = sizeof(double) * lpc_order;
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const size_t lpci_size = sizeof(float) * lpc_order;
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const size_t work_size = sizeof(float) * (extra_bkwd + lpc_order + extra_fwd);
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const size_t new_size = tdata_size + aut_size + lpc_size + lpci_size + work_size;
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if(new_size > *extrapolate_buffer_size) {
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*extrapolate_buffer = realloc(*extrapolate_buffer, new_size);
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*extrapolate_buffer_size = new_size;
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}
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float *tdata = (float *)(*extrapolate_buffer); // for 1 channel only
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double *aut = (double *)(*extrapolate_buffer + tdata_size);
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double *lpc = (double *)(*extrapolate_buffer + tdata_size + aut_size);
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float *lpci = (float *)(*extrapolate_buffer + tdata_size + aut_size + lpc_size);
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float *work = (float *)(*extrapolate_buffer + tdata_size + aut_size + lpc_size + lpci_size);
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for(int c = 0; c < nch; c++) {
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if(extra_bkwd) {
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for(int i = 0; i < (int)data_len; i++)
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tdata[data_len - 1 - i] = data[i * nch + c];
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} else {
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for(int i = 0; i < (int)data_len; i++)
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tdata[i] = data[i * nch + c];
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}
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apply_window(tdata, data_len);
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vorbis_lpc_from_data(tdata, lpci, (int)data_len, lpc_order, aut, lpc);
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// restore after apply_window
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if(extra_bkwd) {
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for(int i = 0; i < (int)data_len; i++)
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tdata[data_len - 1 - i] = data[i * nch + c];
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} else {
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for(int i = 0; i < (int)data_len; i++)
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tdata[i] = data[i * nch + c];
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}
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vorbis_lpc_predict(lpci, tdata + data_len - lpc_order, lpc_order, tdata + data_len, extra_fwd + extra_bkwd, work);
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if(extra_bkwd) {
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for(int i = 0; i < extra_bkwd; i++)
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data[(-i - 1) * nch + c] = tdata[data_len + i];
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} else {
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for(int i = 0; i < extra_fwd; i++)
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data[(i + data_len) * nch + c] = tdata[data_len + i];
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}
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}
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}
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