FreeCalypso > hg > gsm-codec-lib
view libtwamr/gc_pred.c @ 581:e2d5cad04cbf
libgsmhr1 RxFE: store CN R0+LPC separately from speech
In the original GSM 06.06 code the ECU for speech mode is entirely
separate from the CN generator, maintaining separate state. (The
main intertie between them is the speech vs CN state variable,
distinguishing between speech and CN BFIs, in addition to the
CN-specific function of distinguishing between initial and update
SIDs.)
In the present RxFE implementation I initially thought that we could
use the same saved_frame buffer for both ECU and CN, overwriting
just the first 4 params (R0 and LPC) when a valid SID comes in.
However, I now realize it was a bad idea: the original code has a
corner case (long sequence of speech-mode BFIs to put the ECU in
state 6, then SID and CN-mode BFIs, then a good speech frame) that
would be broken by that buffer reuse approach. We could eliminate
this corner case by resetting the ECU state when passing through
a CN insertion period, but doing so would needlessly increase
the behavioral diffs between GSM 06.06 and our version.
Solution: use a separate CN-specific buffer for CN R0+LPC parameters,
and match the behavior of GSM 06.06 code in this regard.
| author | Mychaela Falconia <falcon@freecalypso.org> |
|---|---|
| date | Thu, 13 Feb 2025 10:02:45 +0000 |
| parents | 7f99b8ed30e5 |
| children |
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/* ***************************************************************************** * * GSM AMR-NB speech codec R98 Version 7.6.0 December 12, 2001 * R99 Version 3.3.0 * REL-4 Version 4.1.0 * ***************************************************************************** * * File : gc_pred.c * Purpose : codebook gain MA prediction * ***************************************************************************** */ /* ***************************************************************************** * MODULE INCLUDE FILE AND VERSION ID ***************************************************************************** */ #include "namespace.h" #include "gc_pred.h" /* ***************************************************************************** * INCLUDE FILES ***************************************************************************** */ #include "typedef.h" #include "basic_op.h" #include "oper_32b.h" #include "cnst.h" #include "no_count.h" #include "log2.h" #include "memops.h" /* ***************************************************************************** * LOCAL VARIABLES AND TABLES ***************************************************************************** */ #define NPRED 4 /* number of prediction taps */ /* MA prediction coefficients (Q13) */ static const Word16 pred[NPRED] = {5571, 4751, 2785, 1556}; /* average innovation energy. */ /* MEAN_ENER = 36.0/constant, constant = 20*Log10(2) */ #define MEAN_ENER_MR122 783741L /* 36/(20*log10(2)) (Q17) */ /* MA prediction coefficients (Q6) */ static const Word16 pred_MR122[NPRED] = {44, 37, 22, 12}; /* minimum quantized energy: -14 dB */ #define MIN_ENERGY -14336 /* 14 Q10 */ #define MIN_ENERGY_MR122 -2381 /* 14 / (20*log10(2)) Q10 */ /* ***************************************************************************** * PUBLIC PROGRAM CODE ***************************************************************************** */ /************************************************************************* * * Function: gc_pred_reset * Purpose: Initializes state memory to zero * ************************************************************************** */ void gc_pred_reset (gc_predState *state) { Word16 i; for(i = 0; i < NPRED; i++) { state->past_qua_en[i] = MIN_ENERGY; state->past_qua_en_MR122[i] = MIN_ENERGY_MR122; } } /************************************************************************* * * FUNCTION: gc_pred_copy() * * PURPOSE: Copy MA predictor state variable * *************************************************************************/ void gc_pred_copy( gc_predState *st_src, /* i : State struct */ gc_predState *st_dest /* o : State struct */ ) { Copy (st_src->past_qua_en, st_dest->past_qua_en, NPRED); Copy (st_src->past_qua_en_MR122, st_dest->past_qua_en_MR122, NPRED); } /************************************************************************* * * FUNCTION: gc_pred() * * PURPOSE: MA prediction of the innovation energy * (in dB/(20*log10(2))) with mean removed). * *************************************************************************/ void gc_pred( gc_predState *st, /* i/o: State struct */ enum Mode mode, /* i : AMR mode */ Word16 *code, /* i : innovative codebook vector (L_SUBFR) */ /* MR122: Q12, other modes: Q13 */ Word16 *exp_gcode0, /* o : exponent of predicted gain factor, Q0 */ Word16 *frac_gcode0,/* o : fraction of predicted gain factor Q15 */ Word16 *exp_en, /* o : exponent of innovation energy, Q0 */ /* (only calculated for MR795) */ Word16 *frac_en /* o : fraction of innovation energy, Q15 */ /* (only calculated for MR795) */ ) { Word16 i; Word32 ener_code; Word16 exp, frac; /*-------------------------------------------------------------------* * energy of code: * * ~~~~~~~~~~~~~~~ * * ener_code = sum(code[i]^2) * *-------------------------------------------------------------------*/ ener_code = L_mac((Word32) 0, code[0], code[0]); /* MR122: Q12*Q12 -> Q25 */ /* others: Q13*Q13 -> Q27 */ for (i = 1; i < L_SUBFR; i++) ener_code = L_mac(ener_code, code[i], code[i]); test (); if (sub (mode, MR122) == 0) { Word32 ener; /* ener_code = ener_code / lcode; lcode = 40; 1/40 = 26214 Q20 */ ener_code = L_mult (round (ener_code), 26214); /* Q9 * Q20 -> Q30 */ /*-------------------------------------------------------------------* * energy of code: * * ~~~~~~~~~~~~~~~ * * ener_code(Q17) = 10 * Log10(energy) / constant * * = 1/2 * Log2(energy) * * constant = 20*Log10(2) * *-------------------------------------------------------------------*/ /* ener_code = 1/2 * Log2(ener_code); Note: Log2=log2+30 */ Log2(ener_code, &exp, &frac); ener_code = L_Comp (sub (exp, 30), frac); /* Q16 for log() */ /* ->Q17 for 1/2 log()*/ /*-------------------------------------------------------------------* * predicted energy: * * ~~~~~~~~~~~~~~~~~ * * ener(Q24) = (Emean + sum{pred[i]*past_en[i]})/constant * * = MEAN_ENER + sum(pred[i]*past_qua_en[i]) * * constant = 20*Log10(2) * *-------------------------------------------------------------------*/ ener = MEAN_ENER_MR122; move32 (); /* Q24 (Q17) */ for (i = 0; i < NPRED; i++) { ener = L_mac (ener, st->past_qua_en_MR122[i], pred_MR122[i]); /* Q10 * Q13 -> Q24 */ /* Q10 * Q6 -> Q17 */ } /*-------------------------------------------------------------------* * predicted codebook gain * * ~~~~~~~~~~~~~~~~~~~~~~~ * * gc0 = Pow10( (ener*constant - ener_code*constant) / 20 ) * * = Pow2(ener-ener_code) * * = Pow2(int(d)+frac(d)) * * * * (store exp and frac for pow2()) * *-------------------------------------------------------------------*/ ener = L_shr (L_sub (ener, ener_code), 1); /* Q16 */ L_Extract(ener, exp_gcode0, frac_gcode0); } else /* all modes except 12.2 */ { Word32 L_tmp; Word16 exp_code, gcode0; /*-----------------------------------------------------------------* * Compute: means_ener - 10log10(ener_code/ L_sufr) * *-----------------------------------------------------------------*/ exp_code = norm_l (ener_code); ener_code = L_shl (ener_code, exp_code); /* Log2 = log2 + 27 */ Log2_norm (ener_code, exp_code, &exp, &frac); /* fact = 10/log2(10) = 3.01 = 24660 Q13 */ L_tmp = Mpy_32_16(exp, frac, -24660); /* Q0.Q15 * Q13 -> Q14 */ /* L_tmp = means_ener - 10log10(ener_code/L_SUBFR) * = means_ener - 10log10(ener_code) + 10log10(L_SUBFR) * = K - fact * Log2(ener_code) * = K - fact * log2(ener_code) - fact*27 * * ==> K = means_ener + fact*27 + 10log10(L_SUBFR) * * means_ener = 33 = 540672 Q14 (MR475, MR515, MR59) * means_ener = 28.75 = 471040 Q14 (MR67) * means_ener = 30 = 491520 Q14 (MR74) * means_ener = 36 = 589824 Q14 (MR795) * means_ener = 33 = 540672 Q14 (MR102) * 10log10(L_SUBFR) = 16.02 = 262481.51 Q14 * fact * 27 = 1331640 Q14 * ----------------------------------------- * (MR475, MR515, MR59) K = 2134793.51 Q14 ~= 16678 * 64 * 2 * (MR67) K = 2065161.51 Q14 ~= 32268 * 32 * 2 * (MR74) K = 2085641.51 Q14 ~= 32588 * 32 * 2 * (MR795) K = 2183945.51 Q14 ~= 17062 * 64 * 2 * (MR102) K = 2134793.51 Q14 ~= 16678 * 64 * 2 */ if (test (), sub (mode, MR102) == 0) { /* mean = 33 dB */ L_tmp = L_mac(L_tmp, 16678, 64); /* Q14 */ } else if (test (), sub (mode, MR795) == 0) { /* ener_code = <xn xn> * 2^27*2^exp_code frac_en = ener_code / 2^16 = <xn xn> * 2^11*2^exp_code <xn xn> = <xn xn>*2^11*2^exp * 2^exp_en := frac_en * 2^exp_en ==> exp_en = -11-exp_code; */ *frac_en = extract_h (ener_code); move16 (); *exp_en = sub (-11, exp_code); move16 (); /* mean = 36 dB */ L_tmp = L_mac(L_tmp, 17062, 64); /* Q14 */ } else if (test (), sub (mode, MR74) == 0) { /* mean = 30 dB */ L_tmp = L_mac(L_tmp, 32588, 32); /* Q14 */ } else if (test (), sub (mode, MR67) == 0) { /* mean = 28.75 dB */ L_tmp = L_mac(L_tmp, 32268, 32); /* Q14 */ } else /* MR59, MR515, MR475 */ { /* mean = 33 dB */ L_tmp = L_mac(L_tmp, 16678, 64); /* Q14 */ } /*-----------------------------------------------------------------* * Compute gcode0. * * = Sum(i=0,3) pred[i]*past_qua_en[i] - ener_code + mean_ener * *-----------------------------------------------------------------*/ L_tmp = L_shl(L_tmp, 10); /* Q24 */ for (i = 0; i < 4; i++) L_tmp = L_mac(L_tmp, pred[i], st->past_qua_en[i]); /* Q13 * Q10 -> Q24 */ gcode0 = extract_h(L_tmp); /* Q8 */ /*-----------------------------------------------------------------* * gcode0 = pow(10.0, gcode0/20) * * = pow(2, 3.3219*gcode0/20) * * = pow(2, 0.166*gcode0) * *-----------------------------------------------------------------*/ /* 5439 Q15 = 0.165985 */ /* (correct: 1/(20*log10(2)) 0.166096 = 5443 Q15) */ test (); if (sub (mode, MR74) == 0) /* For IS641 bitexactness */ L_tmp = L_mult(gcode0, 5439); /* Q8 * Q15 -> Q24 */ else L_tmp = L_mult(gcode0, 5443); /* Q8 * Q15 -> Q24 */ L_tmp = L_shr(L_tmp, 8); /* -> Q16 */ L_Extract(L_tmp, exp_gcode0, frac_gcode0); /* -> Q0.Q15 */ } } /************************************************************************* * * FUNCTION: gc_pred_update() * * PURPOSE: update MA predictor with last quantized energy * *************************************************************************/ void gc_pred_update( gc_predState *st, /* i/o: State struct */ Word16 qua_ener_MR122, /* i : quantized energy for update, Q10 */ /* (log2(qua_err)) */ Word16 qua_ener /* i : quantized energy for update, Q10 */ /* (20*log10(qua_err)) */ ) { Word16 i; for (i = 3; i > 0; i--) { st->past_qua_en[i] = st->past_qua_en[i - 1]; move16 (); st->past_qua_en_MR122[i] = st->past_qua_en_MR122[i - 1]; move16 (); } st->past_qua_en_MR122[0] = qua_ener_MR122; /* log2 (qua_err), Q10 */ move16 (); st->past_qua_en[0] = qua_ener; /* 20*log10(qua_err), Q10 */ move16 (); } /************************************************************************* * * FUNCTION: gc_pred_average_limited() * * PURPOSE: get average of MA predictor state values (with a lower limit) * [used in error concealment] * *************************************************************************/ void gc_pred_average_limited( gc_predState *st, /* i: State struct */ Word16 *ener_avg_MR122, /* o: everaged quantized energy, Q10 */ /* (log2(qua_err)) */ Word16 *ener_avg /* o: averaged quantized energy, Q10 */ /* (20*log10(qua_err)) */ ) { Word16 av_pred_en; Word16 i; /* do average in MR122 mode (log2() domain) */ av_pred_en = 0; move16 (); for (i = 0; i < NPRED; i++) { av_pred_en = add (av_pred_en, st->past_qua_en_MR122[i]); } /* av_pred_en = 0.25*av_pred_en */ av_pred_en = mult (av_pred_en, 8192); /* if (av_pred_en < -14/(20Log10(2))) av_pred_en = .. */ test (); if (sub (av_pred_en, MIN_ENERGY_MR122) < 0) { av_pred_en = MIN_ENERGY_MR122; move16 (); } *ener_avg_MR122 = av_pred_en; move16 (); /* do average for other modes (20*log10() domain) */ av_pred_en = 0; move16 (); for (i = 0; i < NPRED; i++) { av_pred_en = add (av_pred_en, st->past_qua_en[i]); } /* av_pred_en = 0.25*av_pred_en */ av_pred_en = mult (av_pred_en, 8192); /* if (av_pred_en < -14) av_pred_en = .. */ test (); if (sub (av_pred_en, MIN_ENERGY) < 0) { av_pred_en = MIN_ENERGY; move16 (); } *ener_avg = av_pred_en; move16 (); }