view libgsmefr/d_plsf_5.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 cc08498ed21b
children
line wrap: on
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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;
}