FreeCalypso > hg > gsm-codec-lib
view libgsmefr/d_plsf_5.c @ 242:f081a6850fb5
libgsmfrp: new refined implementation
The previous implementation exhibited the following defects,
which are now fixed:
1) The last received valid SID was cached forever for the purpose of
handling future invalid SIDs - we could have received some valid
SID ages ago, then lots of speech or NO_DATA, and if we then get
an invalid SID, we would resurrect the last valid SID from ancient
history - a bad design. In our new design, we handle invalid SID
based on the current state, much like BFI.
2) GSM 06.11 spec says clearly that after the second lost SID
(received BFI=1 && TAF=1 in CN state) we need to gradually decrease
the output level, rather than jump directly to emitting silence
frames - we previously failed to implement such logic.
3) Per GSM 06.12 section 5.2, Xmaxc should be the same in all 4 subframes
in a SID frame. What should we do if we receive an otherwise valid
SID frame with different Xmaxc? Our previous approach would
replicate this Xmaxc oddity in every subsequent generated CN frame,
which is rather bad. In our new design, the very first CN frame
(which can be seen as a transformation of the SID frame itself)
retains the original 4 distinct Xmaxc, but all subsequent CN frames
are based on the Xmaxc from the last subframe of the most recent SID.
author | Mychaela Falconia <falcon@freecalypso.org> |
---|---|
date | Tue, 09 May 2023 05:16:31 +0000 |
parents | cc08498ed21b |
children |
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/************************************************************************* * * FUNCTION: D_plsf_5() * * PURPOSE: Decodes the 2 sets of LSP parameters in a frame using the * received quantization indices. * * DESCRIPTION: * The two sets of LSFs are quantized using split by 5 matrix * quantization (split-MQ) with 1st order MA prediction. * * See "q_plsf_5.c" for more details about the quantization procedure * *************************************************************************/ #include "gsm_efr.h" #include "typedef.h" #include "namespace.h" #include "basic_op.h" #include "no_count.h" #include "codec.h" #include "sig_proc.h" #include "memops.h" #include "q_plsf5_tab.h" /* Codebooks of LSF prediction residual */ #include "cnst.h" #include "dtx.h" #include "dec_state.h" /* M ->order of linear prediction filter */ /* LSF_GAP -> Minimum distance between LSF after quantization */ /* 50 Hz = 205 */ /* PRED_FAC -> Prediction factor = 0.65 */ /* ALPHA -> 0.9 */ /* ONE_ALPHA-> (1.0-ALPHA) */ #define M 10 #define LSF_GAP 205 #define PRED_FAC 21299 #define ALPHA 31128 #define ONE_ALPHA 1639 void D_plsf_5 ( struct EFR_decoder_state *st, const Word16 *indice, /* input : quantization indices of 5 submatrices */ Word16 *lsp1_q, /* output: quantized 1st LSP vector */ Word16 *lsp2_q, /* output: quantized 2nd LSP vector */ Word16 bfi, /* input : bad frame indicator (set to 1 if a bad frame is received) */ Word16 rxdtx_ctrl, /* input : RX DTX control word */ Word16 rx_dtx_state /* input : state of the comfort noise insertion period */ ) { Word16 i; const Word16 *p_dico; Word16 temp, sign; Word16 lsf1_r[M], lsf2_r[M]; Word16 lsf1_q[M], lsf2_q[M]; /* Update comfort noise LSF quantizer memory */ if ((rxdtx_ctrl & RX_UPD_SID_QUANT_MEM) != 0) { update_lsf_p_CN (st->lsf_old_rx, st->lsf_p_CN); } /* Handle cases of comfort noise LSF decoding in which past valid SID frames are repeated */ if (((rxdtx_ctrl & RX_NO_TRANSMISSION) != 0) || ((rxdtx_ctrl & RX_INVALID_SID_FRAME) != 0) || ((rxdtx_ctrl & RX_LOST_SID_FRAME) != 0)) { if ((rxdtx_ctrl & RX_NO_TRANSMISSION) != 0) { /* DTX active: no transmission. Interpolate LSF values in memory */ interpolate_CN_lsf (st->lsf_old_CN, st->lsf_new_CN, lsf2_q, rx_dtx_state); } else { /* Invalid or lost SID frame: use LSFs from last good SID frame */ for (i = 0; i < M; i++) { st->lsf_old_CN[i] = st->lsf_new_CN[i]; lsf2_q[i] = st->lsf_new_CN[i]; st->past_r2_q[i] = 0; } } for (i = 0; i < M; i++) { st->past_lsf_q[i] = lsf2_q[i]; } /* convert LSFs to the cosine domain */ Lsf_lsp (lsf2_q, lsp2_q, M); return; } if (bfi != 0) /* if bad frame */ { /* use the past LSFs slightly shifted towards their mean */ for (i = 0; i < M; i++) { /* lsfi_q[i] = ALPHA*past_lsf_q[i] + ONE_ALPHA*mean_lsf[i]; */ lsf1_q[i] = add (mult (st->past_lsf_q[i], ALPHA), mult (mean_lsf[i], ONE_ALPHA)); lsf2_q[i] = lsf1_q[i]; } /* estimate past quantized residual to be used in next frame */ for (i = 0; i < M; i++) { /* temp = mean_lsf[i] + past_r2_q[i] * PRED_FAC; */ temp = add (mean_lsf[i], mult (st->past_r2_q[i], PRED_FAC)); st->past_r2_q[i] = sub (lsf2_q[i], temp); } } else /* if good LSFs received */ { /* decode prediction residuals from 5 received indices */ p_dico = &dico1_lsf[shl (indice[0], 2)]; lsf1_r[0] = *p_dico++; move16 (); lsf1_r[1] = *p_dico++; move16 (); lsf2_r[0] = *p_dico++; move16 (); lsf2_r[1] = *p_dico++; move16 (); p_dico = &dico2_lsf[shl (indice[1], 2)]; lsf1_r[2] = *p_dico++; move16 (); lsf1_r[3] = *p_dico++; move16 (); lsf2_r[2] = *p_dico++; move16 (); lsf2_r[3] = *p_dico++; move16 (); sign = indice[2] & 1; logic16 (); i = shr (indice[2], 1); p_dico = &dico3_lsf[shl (i, 2)]; move16 (); test (); if (sign == 0) { lsf1_r[4] = *p_dico++; move16 (); lsf1_r[5] = *p_dico++; move16 (); lsf2_r[4] = *p_dico++; move16 (); lsf2_r[5] = *p_dico++; move16 (); } else { lsf1_r[4] = negate (*p_dico++); move16 (); lsf1_r[5] = negate (*p_dico++); move16 (); lsf2_r[4] = negate (*p_dico++); move16 (); lsf2_r[5] = negate (*p_dico++); move16 (); } p_dico = &dico4_lsf[shl (indice[3], 2)];move16 (); lsf1_r[6] = *p_dico++; move16 (); lsf1_r[7] = *p_dico++; move16 (); lsf2_r[6] = *p_dico++; move16 (); lsf2_r[7] = *p_dico++; move16 (); p_dico = &dico5_lsf[shl (indice[4], 2)];move16 (); lsf1_r[8] = *p_dico++; move16 (); lsf1_r[9] = *p_dico++; move16 (); lsf2_r[8] = *p_dico++; move16 (); lsf2_r[9] = *p_dico++; move16 (); /* Compute quantized LSFs and update the past quantized residual */ /* Use lsf_p_CN as predicted LSF vector in case of no speech activity */ if ((rxdtx_ctrl & RX_SP_FLAG) != 0) { for (i = 0; i < M; i++) { temp = add (mean_lsf[i], mult (st->past_r2_q[i], PRED_FAC)); lsf1_q[i] = add (lsf1_r[i], temp); lsf2_q[i] = add (lsf2_r[i], temp); st->past_r2_q[i] = lsf2_r[i]; } } else { /* Valid SID frame */ for (i = 0; i < M; i++) { lsf2_q[i] = add (lsf2_r[i], st->lsf_p_CN[i]); /* Use the dequantized values of lsf2 also for lsf1 */ lsf1_q[i] = lsf2_q[i]; st->past_r2_q[i] = 0; } } } /* verification that LSFs have minimum distance of LSF_GAP Hz */ Reorder_lsf (lsf1_q, LSF_GAP, M); Reorder_lsf (lsf2_q, LSF_GAP, M); if ((rxdtx_ctrl & RX_FIRST_SID_UPDATE) != 0) { for (i = 0; i < M; i++) { st->lsf_new_CN[i] = lsf2_q[i]; } } if ((rxdtx_ctrl & RX_CONT_SID_UPDATE) != 0) { for (i = 0; i < M; i++) { st->lsf_old_CN[i] = st->lsf_new_CN[i]; st->lsf_new_CN[i] = lsf2_q[i]; } } if ((rxdtx_ctrl & RX_SP_FLAG) != 0) { /* Update lsf history with quantized LSFs when speech activity is present. If the current frame is a bad one, update with most recent good comfort noise LSFs */ if (bfi==0) { update_lsf_history (lsf1_q, lsf2_q, st->lsf_old_rx); } else { update_lsf_history (st->lsf_new_CN, st->lsf_new_CN, st->lsf_old_rx); } for (i = 0; i < M; i++) { st->lsf_old_CN[i] = lsf2_q[i]; } } else { interpolate_CN_lsf (st->lsf_old_CN, st->lsf_new_CN, lsf2_q, rx_dtx_state); } for (i = 0; i < M; i++) { st->past_lsf_q[i] = lsf2_q[i]; } /* convert LSFs to the cosine domain */ Lsf_lsp (lsf1_q, lsp1_q, M); Lsf_lsp (lsf2_q, lsp2_q, M); return; }