#include "libavutil/mathematics.h"
/**
- * initial coefficient to perform bandwidth expansion on LPC
- *
- * @note: 0.9883 looks like an approximation of 253/256.
- *
- * TIA/EIA/IS-733 2.4.3.3.6 6
- */
-#define QCELP_BANDWITH_EXPANSION_COEFF 0.9883
-
-/**
* Computes the Pa / (1 + z(-1)) or Qa / (1 - z(-1)) coefficients
* needed for LSP to LPC conversion.
* We only need to calculate the 6 first elements of the polynomial.
double paf = pa[i+1] + pa[i];
double qaf = qa[i+1] - qa[i];
- lpc[i ] = 0.5 * (paf+qaf);
- lpc[9-i] = 0.5 * (paf-qaf);
- }
-}
-
-/**
- * Reconstructs LPC coefficients from the line spectral pair frequencies
- * and performs bandwidth expansion.
- *
- * @param lspf line spectral pair frequencies
- * @param lpc linear predictive coding coefficients
- *
- * @note: bandwith_expansion_coeff could be precalculated into a table
- * but it seems to be slower on x86
- *
- * TIA/EIA/IS-733 2.4.3.3.5
- */
-void ff_qcelp_lspf2lpc(const float *lspf, float *lpc)
-{
- double lsf[10];
- double bandwith_expansion_coeff = QCELP_BANDWITH_EXPANSION_COEFF;
- int i;
-
- for (i=0; i<10; i++)
- lsf[i] = cos(M_PI * lspf[i]);
-
- ff_celp_lspf2lpc(lsf, lpc);
-
- for (i=0; i<10; i++)
- {
- lpc[i] *= bandwith_expansion_coeff;
- bandwith_expansion_coeff *= QCELP_BANDWITH_EXPANSION_COEFF;
+ lpc[i ] = 0.5*(paf+qaf);
+ lpc[9-i] = 0.5*(paf-qaf);
}
}
*
* TIA/EIA/IS-733 2.4.3.3.5
*/
-void ff_qcelp_lspf2lpc(const float *lspf, float *lpc);
+void ff_celp_lspf2lpc(const double *lspf, float *lpc);
static void weighted_vector_sumf(float *out, const float *in_a,
const float *in_b, float weight_coeff_a,
}
/**
+ * Reconstructs LPC coefficients from the line spectral pair frequencies
+ * and performs bandwidth expansion.
+ *
+ * @param lspf line spectral pair frequencies
+ * @param lpc linear predictive coding coefficients
+ *
+ * @note: bandwith_expansion_coeff could be precalculated into a table
+ * but it seems to be slower on x86
+ *
+ * TIA/EIA/IS-733 2.4.3.3.5
+ */
+void lspf2lpc(const float *lspf, float *lpc)
+{
+ double lsf[10];
+ double bandwith_expansion_coeff = QCELP_BANDWITH_EXPANSION_COEFF;
+ int i;
+
+ for (i=0; i<10; i++)
+ lsf[i] = cos(M_PI * lspf[i]);
+
+ ff_celp_lspf2lpc(lsf, lpc);
+
+ for (i=0; i<10; i++)
+ {
+ lpc[i] *= bandwith_expansion_coeff;
+ bandwith_expansion_coeff *= QCELP_BANDWITH_EXPANSION_COEFF;
+ }
+}
+
+/**
* Interpolates LSP frequencies and computes LPC coefficients
* for a given bitrate & pitch subframe.
*
{
weighted_vector_sumf(interpolated_lspf, curr_lspf, q->prev_lspf,
weight, 1.0 - weight, 10);
- ff_qcelp_lspf2lpc(interpolated_lspf, lpc);
+ lspf2lpc(interpolated_lspf, lpc);
}else if(q->bitrate >= RATE_QUARTER ||
(q->bitrate == I_F_Q && !subframe_num))
- ff_qcelp_lspf2lpc(curr_lspf, lpc);
+ lspf2lpc(curr_lspf, lpc);
else if(q->bitrate == SILENCE && !subframe_num)
- ff_qcelp_lspf2lpc(q->prev_lspf, lpc);
+ lspf2lpc(q->prev_lspf, lpc);
}
static qcelp_packet_rate buf_size2bitrate(const int buf_size)