FreeCalypso > hg > gsm-codec-lib
view libgsmefr/d1035pf.c @ 183:452c1d5a6268
libgsmefr BFI w/o data: emit zero output after decoder reset
In real-life usage, each EFR decoder session will most likely begin
with lots of BFI frames before the first real frame arrives. However,
because the spec-defined home state of the decoder is speech rather
than CN, our regular logic for BFI w/o data would have to feed
pseudorandom noise to the decoder (in the "fixed codebook excitation
pulses" part), which is silly to do at the beginning of the decoder
session right out of reset. Therefore, let's check reset_flag_old,
and if we are still in the reset state, simply emit zero output.
author | Mychaela Falconia <falcon@freecalypso.org> |
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date | Tue, 03 Jan 2023 00:12:18 +0000 |
parents | d80e9f12a1d1 |
children | 6ad363f7ea30 |
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/************************************************************************* * * FUNCTION: dec_10i40_35bits() * * PURPOSE: Builds the innovative codevector from the received * index of algebraic codebook. * * See c1035pf.c for more details about the algebraic codebook structure. * *************************************************************************/ #include "gsm_efr.h" #include "typedef.h" #include "namespace.h" #include "basic_op.h" #include "memops.h" #include "no_count.h" #include "codec.h" #define L_CODE 40 /* codevector length */ #define NB_PULSE 10 /* number of pulses */ #define NB_TRACK 5 /* number of track */ void dec_10i40_35bits ( const Word16 index[], /* (i) : index of 10 pulses (sign+position) */ Word16 cod[] /* (o) : algebraic (fixed) codebook excitation */ ) { static const Word16 dgray[8] = {0, 1, 3, 2, 5, 6, 4, 7}; Word16 i, j, pos1, pos2, sign, tmp; Set_zero (cod, L_CODE); /* decode the positions and signs of pulses and build the codeword */ for (j = 0; j < NB_TRACK; j++) { /* compute index i */ tmp = index[j]; move16 (); i = tmp & 7; logic16 (); i = dgray[i]; move16 (); i = extract_l (L_shr (L_mult (i, 5), 1)); pos1 = add (i, j); /* position of pulse "j" */ i = shr (tmp, 3) & 1; logic16 (); if (i == 0) { sign = 4096; move16 (); /* +1.0 */ } else { sign = -4096; move16 (); /* -1.0 */ } cod[pos1] = sign; move16 (); /* compute index i */ i = index[add (j, 5)] & 7; logic16 (); i = dgray[i]; move16 (); i = extract_l (L_shr (L_mult (i, 5), 1)); pos2 = add (i, j); /* position of pulse "j+5" */ if (sub (pos2, pos1) < 0) { sign = negate (sign); } cod[pos2] = add (cod[pos2], sign); move16 (); } return; }