FreeCalypso > hg > gsm-codec-lib
view libgsmefr/pred_lt6.c @ 467:ad032051166a
doc: AMR-EFR-hybrid-emu new article
author | Mychaela Falconia <falcon@freecalypso.org> |
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date | Sun, 12 May 2024 23:54:43 +0000 |
parents | db8e0b69a6bb |
children |
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/************************************************************************* * * FUNCTION: Pred_lt_6() * * PURPOSE: Compute the result of long term prediction with fractional * interpolation of resolution 1/6. (Interpolated past excitation). * * DESCRIPTION: * The past excitation signal at the given delay is interpolated at * the given fraction to build the adaptive codebook excitation. * On return exc[0..L_subfr-1] contains the interpolated signal * (adaptive codebook excitation). * *************************************************************************/ #include "gsm_efr.h" #include "typedef.h" #include "namespace.h" #include "basic_op.h" #include "no_count.h" #include "codec.h" #define UP_SAMP 6 #define L_INTERPOL 10 #define FIR_SIZE (UP_SAMP*L_INTERPOL+1) /* 1/6 resolution interpolation filter (-3 dB at 3600 Hz) */ static const Word16 inter_6[FIR_SIZE] = { 29443, 28346, 25207, 20449, 14701, 8693, 3143, -1352, -4402, -5865, -5850, -4673, -2783, -672, 1211, 2536, 3130, 2991, 2259, 1170, 0, -1001, -1652, -1868, -1666, -1147, -464, 218, 756, 1060, 1099, 904, 550, 135, -245, -514, -634, -602, -451, -231, 0, 191, 308, 340, 296, 198, 78, -36, -120, -163, -165, -132, -79, -19, 34, 73, 91, 89, 70, 38, 0 }; void Pred_lt_6 ( Word16 exc[], /* in/out: excitation buffer */ Word16 T0, /* input : integer pitch lag */ Word16 frac, /* input : fraction of lag */ Word16 L_subfr /* input : subframe size */ ) { Word16 i, j, k; Word16 *x0, *x1, *x2; const Word16 *c1, *c2; Word32 s; x0 = &exc[-T0]; move16 (); frac = negate (frac); test (); if (frac < 0) { frac = add (frac, UP_SAMP); x0--; } for (j = 0; j < L_subfr; j++) { x1 = x0++; move16 (); x2 = x0; move16 (); c1 = &inter_6[frac]; c2 = &inter_6[sub (UP_SAMP, frac)]; s = 0; move32 (); for (i = 0, k = 0; i < L_INTERPOL; i++, k += UP_SAMP) { s = L_mac (s, x1[-i], c1[k]); s = L_mac (s, x2[i], c2[k]); } exc[j] = round (s); move16 (); } return; }