diff --git a/lib_com/ivas_cnst.h b/lib_com/ivas_cnst.h
index 47ce9b8710e9d246bf21389e9e5e1aff82ffd2e4..abd6865ca09c1fa0288f35ebb264e03ca43f3f43 100644
--- a/lib_com/ivas_cnst.h
+++ b/lib_com/ivas_cnst.h
@@ -1063,6 +1063,11 @@ typedef enum
 #define IVAS_ACTIVEW_DM_F_SCALE_VLBR            0.25f
 #define IVAS_SPAR_FOA_DFLT_FREQ_PER_CHAN        24000
 
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+#define IVAS_SPAR_DYN_ACTIVEW_THRESH           (0.0039f)
+#define IVAS_SPAR_SIDE_CH_DYN_ACTIVEW_THRESH   (32.0f)
+#endif
+
 #define MAX_QUANT_STRATS                        3
 #define MAX_CODING_STRATS                       3
 #define IVAS_NUM_PROB_MODELS                    4
diff --git a/lib_com/ivas_fb_mixer.c b/lib_com/ivas_fb_mixer.c
index a94a92c548785667f9cff7d72d53bf681d57ea4a..070a0ff5faf42c23c46d09360719d546789afc35 100644
--- a/lib_com/ivas_fb_mixer.c
+++ b/lib_com/ivas_fb_mixer.c
@@ -590,14 +590,22 @@ void ivas_fb_mixer_get_windowed_fr(
  *
  * FB Mixer cross fading
  *-----------------------------------------------------------------------------------------*/
-
-static void ivas_fb_mixer_cross_fading(
-    IVAS_FB_MIXER_HANDLE hFbMixer,
-    float **ppOut_pcm,
-    float *pMdft_out_old,
-    float *pMdft_out_new,
-    const int16_t ch,
-    const int16_t frame_len )
+#ifndef FIX_SBA_VANISHING_RESIDUAL
+static
+#endif
+    void
+    ivas_fb_mixer_cross_fading(
+        IVAS_FB_MIXER_HANDLE hFbMixer,
+        float **ppOut_pcm,
+        float *pMdft_out_old,
+        float *pMdft_out_new,
+        const int16_t ch,
+        const int16_t frame_len
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+        ,
+        const int16_t cf_offset
+#endif
+    )
 {
     int16_t k, fade_start_offset, fade_end_offset;
 
@@ -608,17 +616,29 @@ static void ivas_fb_mixer_cross_fading(
 
         for ( k = 0; k < fade_start_offset; k++ )
         {
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+            ppOut_pcm[ch][k] = pMdft_out_old[k + cf_offset];
+#else
             ppOut_pcm[ch][k] = pMdft_out_old[k + frame_len];
+#endif
         }
 
         for ( k = fade_start_offset; k < fade_end_offset; k++ )
         {
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+            ppOut_pcm[ch][k] = pMdft_out_new[k + cf_offset] * hFbMixer->pFilterbank_cross_fade[k - fade_start_offset] + pMdft_out_old[k + cf_offset] * ( 1.0f - hFbMixer->pFilterbank_cross_fade[k - fade_start_offset] );
+#else
             ppOut_pcm[ch][k] = pMdft_out_new[k + frame_len] * hFbMixer->pFilterbank_cross_fade[k - fade_start_offset] + pMdft_out_old[k + frame_len] * ( 1.0f - hFbMixer->pFilterbank_cross_fade[k - fade_start_offset] );
+#endif
         }
 
         for ( k = fade_end_offset; k < frame_len; k++ )
         {
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+            ppOut_pcm[ch][k] = pMdft_out_new[k + cf_offset];
+#else
             ppOut_pcm[ch][k] = pMdft_out_new[k + frame_len];
+#endif
         }
     }
     else
@@ -627,7 +647,11 @@ static void ivas_fb_mixer_cross_fading(
 
         for ( k = 0; k < frame_len; k++ )
         {
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+            ppOut_pcm[ch][k] = pMdft_out_new[k + cf_offset];
+#else
             ppOut_pcm[ch][k] = pMdft_out_new[k + frame_len];
+#endif
         }
     }
 
@@ -717,7 +741,12 @@ void ivas_fb_mixer_process(
             ivas_imdft( pOut_fr_re, pOut_fr_im, pMdft_out[hist], frame_len );
         }
 
-        ivas_fb_mixer_cross_fading( hFbMixer, ppOut_pcm, pMdft_out[0], pMdft_out[1], ch, frame_len );
+        ivas_fb_mixer_cross_fading( hFbMixer, ppOut_pcm, pMdft_out[0], pMdft_out[1], ch, frame_len
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+                                    ,
+                                    frame_len
+#endif
+        );
     }
 
     return;
diff --git a/lib_com/ivas_prot.h b/lib_com/ivas_prot.h
index d6efef32df9a50950a6b6ccf6af083252d175b88..315970a6c29cea9f48b08e5f8919159f8bba99f3 100644
--- a/lib_com/ivas_prot.h
+++ b/lib_com/ivas_prot.h
@@ -114,6 +114,18 @@ ivas_error ivas_spar_md_enc_init
     const int16_t sba_order                                   /* i  : Ambisonic (SBA) order    */
 );
 
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+int16_t ivas_spar_get_activeW_flag(
+    ivas_enc_cov_handler_state_t *hCovEnc,
+    float *cov_real[IVAS_SPAR_MAX_CH][IVAS_SPAR_MAX_CH],
+    float *cov_dtx_real[IVAS_SPAR_MAX_CH][IVAS_SPAR_MAX_CH],
+    const int16_t dtx_vad,
+    const int16_t nchan_inp,
+	const int16_t nchan_transport,
+	int16_t *res_ind,
+	const int16_t *dmx_order);
+#endif
+
 ivas_error ivas_sba_enc_reconfigure(
     Encoder_Struct *st_ivas                                     /* i/o: IVAS encoder structure                  */
 );
@@ -4390,8 +4402,13 @@ ivas_error ivas_spar_md_enc_process(
     const int16_t nchan_inp,
     const int16_t sba_order,                                    /* i  : Ambisonic (SBA) order                   */
     float *prior_mixer[IVAS_MAX_FB_MIXER_OUT_CH][IVAS_MAX_SPAR_FB_MIXER_IN_CH]                                  /* i  : prior mixer_matrix     */
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+     ,
+     const int16_t dyn_active_w_flag            /* i : flag to indicate dynamic active W*/
+#endif
 #ifdef FIX_527_SBA_MONO_INPUT
-    ,const int16_t dirac_mono_flag
+    ,
+	const int16_t dirac_mono_flag             /* i : flag to indicate mono only mode in SBA*/
 #endif
 );
 
@@ -4411,6 +4428,10 @@ void ivas_compute_spar_params(
     ivas_spar_md_t *hSparMd,
     float *pWscale,
     const int16_t from_dirac 
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+    ,
+    const int16_t dyn_active_w_flag
+#endif
 );
 
 void ivas_create_fullr_dmx_mat(
@@ -4438,6 +4459,10 @@ void ivas_calc_c_p_coeffs(
     ,
     const int16_t planarCP 
 #endif
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+    ,
+    const int16_t dyn_active_w_flag
+#endif
 );
 
 void ivas_get_spar_md_from_dirac(
@@ -4456,6 +4481,10 @@ void ivas_get_spar_md_from_dirac(
 	,
     const uint8_t useLowerRes,
     const int16_t active_w_vlbr
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+    ,
+    const int16_t  dyn_active_w_flag
+#endif
 );
 
 /*! r: number of MD subframes */
@@ -4525,7 +4554,11 @@ void ivas_spar_to_dirac(
     ivas_spar_md_dec_state_t *hMdDec,                           /* i/o: SPAR MD decoder handle                  */
     const int16_t dtx_vad,                                      /* i  : DTX frame flag                          */
     const int16_t num_bands_out,                                /* i  : number of output bands                  */
-    const int16_t bw					        /* i  : band joining factor                     */
+    const int16_t bw					                        /* i  : band joining factor                     */
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+    ,
+    const int16_t dyn_active_w_flag                            /* i  : dynamic active W flag                     */
+#endif
 );
 
 void ivas_spar_update_md_hist(
@@ -4585,6 +4618,14 @@ void ivas_enc_cov_handler_process(
     const int16_t dtx_vad,
     const int16_t transient_det[2],
     const int16_t HOA_md_ind[IVAS_SPAR_MAX_CH]
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+    ,
+    int16_t *res_ind,
+    const int16_t *remix_order,
+    int16_t *dyn_active_w_flag,
+	const int16_t nchan_transport,
+	const int16_t is_sba
+#endif
 );
 
 ivas_error ivas_spar_covar_smooth_enc_open( 
@@ -5935,6 +5976,18 @@ void ivas_fb_mixer_get_in_out_mapping(
     int16_t in_out_mixer_map[IVAS_MAX_FB_MIXER_OUT_CH][IVAS_MAX_SPAR_FB_MIXER_IN_CH]   /* i/o: mixing mapping       */
 );
 
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+void ivas_fb_mixer_cross_fading(
+        IVAS_FB_MIXER_HANDLE hFbMixer,
+        float **ppOut_pcm,
+        float *pMdft_out_old,
+        float *pMdft_out_new,
+        const int16_t ch,
+        const int16_t frame_len,
+        const int16_t cf_offset
+    );
+#endif
+
 /*! r: number of spectral bands */
 int16_t ivas_get_num_bands_from_bw_idx( 
     const int16_t bwidth                                        /* i  : audio bandwidth                             */
diff --git a/lib_com/ivas_spar_com.c b/lib_com/ivas_spar_com.c
index d597d133fdb1338edae6d76e1181f0e22c3396f0..fa462313d6beb05395520c7048e986171c8a669a 100644
--- a/lib_com/ivas_spar_com.c
+++ b/lib_com/ivas_spar_com.c
@@ -77,11 +77,22 @@
  *------------------------------------------------------------------------------------------*/
 
 
-static void ivas_get_pred_coeffs( float *pppCov_mat_re[IVAS_SPAR_MAX_CH][IVAS_SPAR_MAX_CH], float ppPred_coeffs_re[IVAS_SPAR_MAX_CH - 1][IVAS_MAX_NUM_BANDS], float ppDM_Fv_re[IVAS_SPAR_MAX_CH - 1][IVAS_MAX_NUM_BANDS], const int16_t in_chans, const int16_t start_band, const int16_t end_band, const int16_t active_w, const int16_t active_w_vlbr, const int16_t dtx_vad, const int16_t from_dirac );
+static void ivas_get_pred_coeffs( float *pppCov_mat_re[IVAS_SPAR_MAX_CH][IVAS_SPAR_MAX_CH], float ppPred_coeffs_re[IVAS_SPAR_MAX_CH - 1][IVAS_MAX_NUM_BANDS], float ppDM_Fv_re[IVAS_SPAR_MAX_CH - 1][IVAS_MAX_NUM_BANDS], const int16_t in_chans, const int16_t start_band, const int16_t end_band, const int16_t active_w, const int16_t active_w_vlbr, const int16_t dtx_vad, const int16_t from_dirac
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+                                  ,
+                                  const int16_t dyn_active_w_flag,
+                                  const int16_t res_ind
+#endif
+);
 
 static void ivas_reorder_array( float in_re[IVAS_SPAR_MAX_CH][IVAS_SPAR_MAX_CH][IVAS_MAX_NUM_BANDS], const int16_t in_chans, const int16_t order[IVAS_SPAR_MAX_CH], float ***mixer_mat, const int16_t start_band, const int16_t end_band );
 
-static void ivas_get_Wscaling_factor( float *pppCov_mat_re[IVAS_SPAR_MAX_CH][IVAS_SPAR_MAX_CH], float pred_coeffs_re[IVAS_SPAR_MAX_CH - 1][IVAS_MAX_NUM_BANDS], float ***mixer_mat, const int16_t start_band, const int16_t end_band, const int16_t dtx_vad, const int16_t num_ch, const int16_t *pNum_dmx, const int16_t bands_bw, const int16_t active_w, const int16_t active_w_vlbr, float *pWscale );
+static void ivas_get_Wscaling_factor( float *pppCov_mat_re[IVAS_SPAR_MAX_CH][IVAS_SPAR_MAX_CH], float pred_coeffs_re[IVAS_SPAR_MAX_CH - 1][IVAS_MAX_NUM_BANDS], float ***mixer_mat, const int16_t start_band, const int16_t end_band, const int16_t dtx_vad, const int16_t num_ch, const int16_t *pNum_dmx, const int16_t bands_bw, const int16_t active_w, const int16_t active_w_vlbr, float *pWscale
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+                                      ,
+                                      const int16_t dyn_active_w_flag
+#endif
+);
 
 static void ivas_calc_post_pred_per_band( float *pppCov_mat_re[IVAS_SPAR_MAX_CH][IVAS_SPAR_MAX_CH], float ***mixer_mat, const int16_t num_ch, const int16_t num_dmx, const int16_t band_idx, float postpred_cov_re[IVAS_SPAR_MAX_CH][IVAS_SPAR_MAX_CH] );
 
@@ -462,7 +473,13 @@ static void ivas_get_pred_coeffs(
     const int16_t active_w,
     const int16_t active_w_vlbr,
     const int16_t dtx_vad,
-    const int16_t from_dirac )
+    const int16_t from_dirac
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+    ,
+    const int16_t dyn_active_w_flag,
+    const int16_t res_ind
+#endif
+)
 {
     int16_t i, j, k, b;
     float abs_value;
@@ -517,7 +534,21 @@ static void ivas_get_pred_coeffs(
         float real[IVAS_SPAR_MAX_CH - 1], dm_beta_re = 0, dm_g[IVAS_MAX_NUM_BANDS];
         float dm_f_local, dm_w, dm_y, DM_F[IVAS_MAX_NUM_BANDS];
         float num_f, den_f, passive_g;
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+        float activew_quad_thresh, g_th_sq;
+        if ( dyn_active_w_flag == 1 )
+        {
+            activew_quad_thresh = 1.0f;
+        }
+        else
+        {
+            activew_quad_thresh = IVAS_LIN_ACTIVEW_QUAD_ACTIVEW_THRESH;
+        }
+        g_th_sq = activew_quad_thresh * activew_quad_thresh;
+#else
         float g_th_sq = IVAS_LIN_ACTIVEW_QUAD_ACTIVEW_THRESH * IVAS_LIN_ACTIVEW_QUAD_ACTIVEW_THRESH;
+#endif
+
 
         set_zero( dm_alpha, IVAS_MAX_NUM_BANDS );
 
@@ -580,7 +611,26 @@ static void ivas_get_pred_coeffs(
             den_f = max( dm_w, 1e-20f );
             passive_g = dm_alpha[b] / den_f;
 
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+            if ( dyn_active_w_flag == 1 )
+            {
+                dm_alpha[b] = 0.0f;
+                dm_w = 0.0f;
+                for ( i = 0; i < pred_dim; i++ )
+                {
+                    dm_v_re[i][b] = 0.0f;
+                }
+                dm_v_re[res_ind - 1][b] = 1.0f;
+                passive_g = activew_quad_thresh;
+            }
+#endif
+
+
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+            if ( passive_g < activew_quad_thresh )
+#else
             if ( passive_g < IVAS_LIN_ACTIVEW_QUAD_ACTIVEW_THRESH )
+#endif
             {
                 /*linear activeW*/
                 dm_y = 0;
@@ -604,7 +654,13 @@ static void ivas_get_pred_coeffs(
                 float sqrt_val;
 
                 /* quadratic activeW */
+
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+                num_f = ( dm_beta_re - ( 2 * dm_alpha[b] * activew_quad_thresh ) );
+#else
                 num_f = ( dm_beta_re - ( 2 * dm_alpha[b] * IVAS_LIN_ACTIVEW_QUAD_ACTIVEW_THRESH ) );
+#endif
+
                 sqrt_val = 4 * dm_alpha[b] * dm_alpha[b] * g_th_sq;
                 sqrt_val += dm_beta_re * dm_beta_re;
                 sqrt_val -= 4 * dm_beta_re * g_th_sq * dm_w;
@@ -613,7 +669,11 @@ static void ivas_get_pred_coeffs(
 
                 den_f = 2 * dm_beta_re * g_th_sq;
                 den_f = max( den_f, 1e-20f );
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+                dm_g[b] = activew_quad_thresh;
+#else
                 dm_g[b] = IVAS_LIN_ACTIVEW_QUAD_ACTIVEW_THRESH;
+#endif
                 DM_F[b] = ( dm_g[b] * num_f ) / den_f;
             }
         }
@@ -651,7 +711,12 @@ static void ivas_get_Wscaling_factor(
     const int16_t bands_bw,
     const int16_t active_w,
     const int16_t active_w_vlbr,
-    float *pWscale )
+    float *pWscale
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+    ,
+    const int16_t dyn_active_w_flag
+#endif
+)
 {
     int16_t b, ch;
     float dm_f_local, abs_val;
@@ -670,7 +735,11 @@ static void ivas_get_Wscaling_factor(
     {
         pWscale[b] = 1;
 
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+        if ( ( active_w == 1 ) && ( dyn_active_w_flag == 0 ) )
+#else
         if ( ( active_w == 1 ) && ( pNum_dmx[b * bands_bw] == 1 ) )
+#endif
         {
             float Gw_sq, g_sq = 0;
 
@@ -1260,9 +1329,13 @@ void ivas_calc_c_p_coeffs(
     ,
     const int16_t planarCP
 #endif
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+    ,
+    const int16_t dyn_active_w_flag
+#endif
 )
 {
-#ifndef FIX_280_PLANAR_CP
+#ifdef FIX_SBA_VANISHING_RESIDUAL
     int16_t i, j;
 #endif
     float postpred_cov_re[IVAS_SPAR_MAX_CH][IVAS_SPAR_MAX_CH];
@@ -1276,36 +1349,29 @@ void ivas_calc_c_p_coeffs(
             ivas_calc_c_coeffs_per_band( pSparMd, i_ts, postpred_cov_re, num_ch, num_dmx, band_idx, dtx_vad );
         }
 
-#ifndef FIX_280_PLANAR_CP
-        if ( planarCP )
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+        if ( dyn_active_w_flag )
         {
             for ( i = 0; i < num_ch - num_dmx; i++ )
             {
-                if ( !keep_planar[i] )
+                for ( j = 0; j < num_dmx - 1; j++ )
                 {
-                    for ( j = 0; j < num_dmx - 1; j++ )
-                    {
-                        pSparMd->band_coeffs[band_idx + i_ts * IVAS_MAX_NUM_BANDS].C_re[i][j] = 0.0f;
-                    }
+                    pSparMd->band_coeffs[band_idx + i_ts * IVAS_MAX_NUM_BANDS].C_re[i][j] = 0.0f;
                 }
             }
         }
 #endif
-
         if ( compute_p_flag == 1 )
         {
             ivas_calc_p_coeffs_per_band( pSparMd, i_ts, postpred_cov_re, num_ch, dtx_vad, num_dmx, band_idx );
         }
 
-#ifndef FIX_280_PLANAR_CP
-        if ( planarCP )
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+        if ( dyn_active_w_flag )
         {
             for ( i = num_dmx; i < num_ch; i++ )
             {
-                if ( !keep_planar[i - num_dmx] )
-                {
-                    pSparMd->band_coeffs[band_idx + i_ts * IVAS_MAX_NUM_BANDS].P_re[i - num_dmx] = 0;
-                }
+                pSparMd->band_coeffs[band_idx + i_ts * IVAS_MAX_NUM_BANDS].P_re[i - num_dmx] = 0;
             }
         }
 #endif
@@ -1560,14 +1626,25 @@ void ivas_compute_spar_params(
     ivas_spar_md_com_cfg *hSparCfg,
     ivas_spar_md_t *hSparMd,
     float *pWscale,
-    const int16_t from_dirac )
+    const int16_t from_dirac
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+    ,
+    const int16_t dyn_active_w_flag
+#endif
+)
 {
     float pred_coeffs_re[IVAS_SPAR_MAX_CH - 1][IVAS_MAX_NUM_BANDS];
     int16_t b, i, ndm;
 
     ivas_get_pred_coeffs( cov_real, pred_coeffs_re, dm_fv_re, num_ch, start_band, end_band, active_w,
                           active_w_vlbr,
-                          dtx_vad, from_dirac );
+                          dtx_vad, from_dirac
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+                          ,
+                          dyn_active_w_flag,
+                          hSparMd->res_ind
+#endif
+    );
 
 #ifdef SPAR_HOA_DBG
     /*fprintf(stderr, "\n\n Prediction Coefficients:\n");
@@ -1601,7 +1678,12 @@ void ivas_compute_spar_params(
     ivas_get_Wscaling_factor( cov_real, pred_coeffs_re, mixer_mat, start_band, end_band, dtx_vad, num_ch,
                               hSparCfg->num_dmx_chans_per_band, bands_bw, active_w,
                               active_w_vlbr,
-                              pWscale );
+                              pWscale
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+                              ,
+                              dyn_active_w_flag
+#endif
+    );
 
     for ( b = start_band; b < end_band; b++ )
     {
@@ -1624,9 +1706,19 @@ void ivas_compute_spar_params(
         if ( ndm != num_ch )
         {
 #ifndef FIX_280_PLANAR_CP
-            ivas_calc_c_p_coeffs( hSparMd, cov_real, i_ts, mixer_mat, num_ch, ndm, b, dtx_vad, 1, 0 );
+            ivas_calc_c_p_coeffs( hSparMd, cov_real, i_ts, mixer_mat, num_ch, ndm, b, dtx_vad, 1, 0
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+                                  ,
+                                  dyn_active_w_flag
+#endif
+            );
 #else
-            ivas_calc_c_p_coeffs( hSparMd, cov_real, i_ts, mixer_mat, num_ch, ndm, b, dtx_vad, 1 );
+            ivas_calc_c_p_coeffs( hSparMd, cov_real, i_ts, mixer_mat, num_ch, ndm, b, dtx_vad, 1
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+                                  ,
+                                  dyn_active_w_flag
+#endif
+            );
 #endif
 
 #ifdef SPAR_HOA_DBG
@@ -1677,7 +1769,12 @@ void ivas_get_spar_md_from_dirac(
     const int16_t dtx_vad,
     float Wscale_d[IVAS_MAX_NUM_BANDS],
     const uint8_t useLowerRes,
-    const int16_t active_w_vlbr )
+    const int16_t active_w_vlbr
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+    ,
+    const int16_t dyn_active_w_flag
+#endif
+)
 {
     int16_t num_ch, band, i, j;
     int16_t block, ch;
@@ -1691,6 +1788,10 @@ void ivas_get_spar_md_from_dirac(
     float **ppMixer_mat[IVAS_MAX_FB_MIXER_OUT_CH];
     float *pMixer_mat[IVAS_MAX_FB_MIXER_OUT_CH][IVAS_MAX_SPAR_FB_MIXER_IN_CH];
     float en_ratio_fac, diff_norm_order1, diff_norm_order2, diff_norm_order3;
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+    int16_t active_w;
+#endif
+
     int16_t ndm, foa_ch, hoa2_ch;
     float P_dir_fact[IVAS_SPAR_MAX_CH - 1];
     const int16_t *remix_order;
@@ -1852,7 +1953,6 @@ void ivas_get_spar_md_from_dirac(
 
             en_ratio_fac = ( 1.0f - diffuseness[band] );
 
-
             for ( i = 0; i < num_ch; i++ )
             {
                 for ( j = 0; j < num_ch; j++ )
@@ -1948,8 +2048,23 @@ void ivas_get_spar_md_from_dirac(
         }
 #endif
 
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+        active_w = ( dyn_active_w_flag == 1 ) || ( hSpar_md_cfg->active_w == 1 );
+#endif
         ivas_compute_spar_params( pCov_real, dm_fv_re, i_ts, ppMixer_mat, start_band, end_band, dtx_vad,
-                                  num_ch, 1, hSpar_md_cfg->active_w, active_w_vlbr, hSpar_md_cfg, hSpar_md, Wscale, 1 );
+                                  num_ch, 1,
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+                                  active_w,
+#else
+                                  hSpar_md_cfg->active_w,
+#endif
+                                  active_w_vlbr,
+                                  hSpar_md_cfg, hSpar_md, Wscale, 1
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+                                  ,
+                                  dyn_active_w_flag
+#endif
+        );
 
         if ( mixer_mat != NULL )
         {
diff --git a/lib_com/ivas_stat_com.h b/lib_com/ivas_stat_com.h
index 04a8c5ed4b7200b25a3b8b9fb682515b166723a3..975fb77a7150d49c77c2a4a3ace871d751da00d8 100644
--- a/lib_com/ivas_stat_com.h
+++ b/lib_com/ivas_stat_com.h
@@ -229,6 +229,10 @@ typedef struct ivas_spar_md_t
     int16_t dtx_vad;
     float en_ratio_slow[IVAS_MAX_NUM_BANDS];
     float ref_pow_slow[IVAS_MAX_NUM_BANDS];
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+    int16_t res_ind;
+    int16_t prior_dyn_active_w_flag;
+#endif
 } ivas_spar_md_t;
 
 typedef struct ivas_spar_md_prev_t
diff --git a/lib_com/options.h b/lib_com/options.h
old mode 100755
new mode 100644
index 26a75598c99f3f47db0653b567def4c31d14797c..0bf8ff7170246fa3134a0f771f531a61b3d36660
--- a/lib_com/options.h
+++ b/lib_com/options.h
@@ -223,6 +223,7 @@
 
 #define MASA_AND_OBJECTS                                /* Nokia: Combination of MASA and objects */
 
+#define FIX_SBA_VANISHING_RESIDUAL                     /*Dlb : Fix for vanishing residual cases when W channel is 0*/
 #define FIX_527_SBA_MONO_INPUT                          /* Dlb : Fix for mono content in a HOA input format */
 #define FIX_653_BUG_IN_SKIP_MATRIX                      /* Dlb: fix for issue #653, bug in the ivas_spar_get_skip_mat function*/
 #define FIX_663_PARAM_ISM_EXT                           /* FhG: Issue 663: ParamISM EXT output improvement */
diff --git a/lib_dec/ivas_spar_decoder.c b/lib_dec/ivas_spar_decoder.c
index 5f8a65e7ac8996ca8743eea34ec5d6f7833f30f3..eaf08a8de82753f131db0b3d2962db8d47e79496 100755
--- a/lib_dec/ivas_spar_decoder.c
+++ b/lib_dec/ivas_spar_decoder.c
@@ -178,7 +178,9 @@ ivas_error ivas_spar_dec_open(
         }
     }
     hSpar->i_subframe = 0;
-
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+    hSpar->AGC_flag = 0;
+#endif
     /*-----------------------------------------------------------------*
      * Configuration - set SPAR high-level parameters
      *-----------------------------------------------------------------*/
@@ -787,7 +789,14 @@ static void ivas_spar_dec_MD(
 
         if ( ivas_total_brate > IVAS_SID_5k2 && !bfi && hSpar->hMdDec->dtx_vad )
         {
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+            if ( hSpar->hMdDec->spar_md_cfg.nchan_transport == 1 )
+            {
+                hSpar->AGC_flag = get_next_indice( st0, 1 );
+            }
+#else
             hSpar->AGC_flag = get_next_indice( st0, 1 );
+#endif
 
             ivas_agc_read_bits( hSpar->hAgcDec, st0, hSpar->hMdDec->spar_md_cfg.nchan_transport, hSpar->AGC_flag );
         }
diff --git a/lib_dec/ivas_spar_md_dec.c b/lib_dec/ivas_spar_md_dec.c
index 62af38c63c0026c99d3055cf51a6bf702f8797f7..1a9a87cddf3ef1be2b5095a29b69cb95ecc6ff5a 100644
--- a/lib_dec/ivas_spar_md_dec.c
+++ b/lib_dec/ivas_spar_md_dec.c
@@ -62,7 +62,12 @@ static const int16_t ivas_spar_dec_plc_spatial_target[IVAS_SPAR_MAX_CH] = { 1, 0
  * Static functions declaration
  *------------------------------------------------------------------------------------------*/
 
-static void ivas_get_spar_matrices( ivas_spar_md_dec_state_t *hMdDec, const int16_t num_bands_out, const int16_t n_ts, const int16_t bw, const int16_t dtx_vad, const int16_t nB, const int16_t numch_out, const int16_t active_w_vlbr );
+static void ivas_get_spar_matrices( ivas_spar_md_dec_state_t *hMdDec, const int16_t num_bands_out, const int16_t n_ts, const int16_t bw, const int16_t dtx_vad, const int16_t nB, const int16_t numch_out, const int16_t active_w_vlbr
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+                                    ,
+                                    const int16_t dyn_active_w_flag
+#endif
+);
 
 #ifndef FIX_280_PLANAR_CP
 static void ivas_decode_arith_bs( ivas_spar_md_dec_state_t *hMdDec, Decoder_State *st, const uint16_t qsi, const int16_t nB, const int16_t bands_bw, int16_t *pDo_diff, const int16_t freq_diff, const int16_t planarCP, const int16_t strat, const int32_t ivas_total_brate );
@@ -805,6 +810,9 @@ void ivas_spar_md_dec_process(
     ivas_spar_md_dec_state_t *hMdDec;
     int16_t num_md_chs;
     int16_t num_md_sub_frames;
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+    int16_t dyn_active_w_flag;
+#endif
     int16_t active_w_vlbr;
 
     hMdDec = st_ivas->hSpar->hMdDec;
@@ -820,6 +828,35 @@ void ivas_spar_md_dec_process(
 #endif
     );
 
+
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+    if ( hMdDec->spar_md_cfg.nchan_transport > 1 && hMdDec->spar_md_cfg.nchan_transport <= 3 )
+    {
+        hMdDec->spar_md.res_ind = 0;
+        dyn_active_w_flag = get_next_indice( st0, 1 );
+        if ( dyn_active_w_flag == 1 )
+        {
+            if ( hMdDec->spar_md_cfg.nchan_transport == 2 )
+            {
+                hMdDec->spar_md.res_ind = get_next_indice( st0, 1 );
+                hMdDec->spar_md.res_ind += hMdDec->spar_md_cfg.nchan_transport;
+            }
+            else if ( hMdDec->spar_md_cfg.nchan_transport == 3 )
+            {
+                hMdDec->spar_md.res_ind = remix_order_set[hMdDec->spar_md_cfg.remix_unmix_order][hMdDec->spar_md_cfg.nchan_transport];
+            }
+        }
+    }
+    else
+    {
+        dyn_active_w_flag = 0;
+        if ( hMdDec->spar_md_cfg.nchan_transport == FOA_CHANNELS )
+        {
+            get_next_indice( st0, 1 );
+        }
+    }
+#endif
+
     ivas_spar_dec_parse_md_bs( hMdDec, st0, &nB, &bw, &dtx_vad, st_ivas->hDecoderConfig->ivas_total_brate,
 #ifndef FIX_280_PLANAR_CP
                                ivas_spar_br_table_consts[hMdDec->table_idx].usePlanarCoeff,
@@ -970,7 +1007,12 @@ void ivas_spar_md_dec_process(
     /* SPAR to DirAC conversion */
     if ( hMdDec->spar_hoa_dirac2spar_md_flag == 1 )
     {
-        ivas_spar_to_dirac( st_ivas, hMdDec, dtx_vad, num_bands_out, bw );
+        ivas_spar_to_dirac( st_ivas, hMdDec, dtx_vad, num_bands_out, bw
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+                            ,
+                            dyn_active_w_flag
+#endif
+        );
     }
 
     /* set correct number of bands*/
@@ -1128,7 +1170,15 @@ void ivas_spar_md_dec_process(
         }
     }
 
-    ivas_get_spar_matrices( hMdDec, num_bands_out, num_md_sub_frames, bw, dtx_vad, nB, num_md_chs, active_w_vlbr );
+    ivas_get_spar_matrices( hMdDec, num_bands_out, num_md_sub_frames, bw, dtx_vad, nB,
+                            num_md_chs,
+                            active_w_vlbr
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+                            ,
+                            dyn_active_w_flag
+#endif
+
+    );
 
 #ifdef DEBUG_SPAR_DIRAC_WRITE_OUT_PRED_PARS
     {
@@ -1439,7 +1489,12 @@ static void ivas_get_spar_matrices(
     const int16_t dtx_vad,
     const int16_t nB,
     const int16_t numch_out,
-    const int16_t active_w_vlbr )
+    const int16_t active_w_vlbr
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+    ,
+    const int16_t dyn_active_w_flag
+#endif
+)
 {
     int16_t num_bands, dmx_ch, split_band;
     int16_t i, j, k, m, b, i_ts, active_w;
@@ -1484,7 +1539,12 @@ static void ivas_get_spar_matrices(
     {
         num_bands = num_bands >> 1;
     }
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+    active_w = ( dyn_active_w_flag == 1 ) || ( hMdDec->spar_md_cfg.active_w == 1 );
+#else
     active_w = hMdDec->spar_md_cfg.active_w;
+#endif
+
     active_w_dm_fac = ( dtx_vad == 0 ) ? IVAS_ACTIVEW_DM_F_SCALE_DTX : ( ( active_w_vlbr ) ? IVAS_ACTIVEW_DM_F_SCALE_VLBR : IVAS_ACTIVEW_DM_F_SCALE );
     for ( i_ts = 0; i_ts < n_ts; i_ts++ )
     {
@@ -1538,6 +1598,13 @@ static void ivas_get_spar_matrices(
                 IVAS_RMULT_FLOAT( tmp_C2_re[0][3], tmp_C1_re[3][0], re );
                 tmp_dm_re[0][0] += re;
 
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+                if ( dyn_active_w_flag == 1 )
+                {
+                    tmp_dm_re[0][0] *= IVAS_SPAR_DYN_ACTIVEW_THRESH;
+                }
+#endif
+
                 tmp_dm_re[0][1] = tmp_C2_re[0][1];
 
                 tmp_dm_re[0][2] = tmp_C2_re[0][2];
@@ -3092,6 +3159,12 @@ static void ivas_parse_parameter_bitstream_dtx(
     sid_bits_len = st0->next_bit_pos - sid_bits_len;
     zero_pad_bits = ( SPAR_DTX_BANDS * SPAR_SID_BITS_TAR_PER_BAND ) - sid_bits_len;
     assert( zero_pad_bits >= 0 );
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+    if ( num_dmx_per_band[0] == 2 )
+    {
+        zero_pad_bits -= 1;
+    }
+#endif
     for ( j = 0; j < zero_pad_bits; j++ )
     {
         get_next_indice( st0, 1 );
@@ -3155,8 +3228,13 @@ void ivas_spar_to_dirac(
     Decoder_Struct *st_ivas,
     ivas_spar_md_dec_state_t *hMdDec, /* i/o: SPAR MD decoder handle      */
     const int16_t dtx_vad,            /* i  : DTX frame flag              */
-    const int16_t num_bands_out,      /* i  : number of output bands      */
-    const int16_t bw                  /* i  : band joining factor         */
+    const int16_t num_bands_out       /* i  : number of output bands      */
+    ,
+    const int16_t bw /* i  : band joining factor         */
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+    ,
+    const int16_t dyn_active_w_flag
+#endif
 )
 {
     DIRAC_DEC_HANDLE hDirAC;
@@ -3181,7 +3259,13 @@ void ivas_spar_to_dirac(
     int16_t enc_param_start_band;
     int16_t active_w_vlbr;
     int16_t i, num_subframes;
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+    int16_t active_w;
+#endif
 
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+    active_w = ( dyn_active_w_flag == 1 ) || ( hMdDec->spar_md_cfg.active_w == 1 );
+#endif
     sba_order_internal = min( st_ivas->sba_analysis_order, IVAS_MAX_SBA_ORDER );
     start_band = 0;
     end_band = min( num_bands_out, SPAR_DIRAC_SPLIT_START_BAND ) / bw;
@@ -3229,8 +3313,11 @@ void ivas_spar_to_dirac(
             if ( st_ivas->nchan_transport == 1 )
             {
                 float w_en_norm, f_scale;
-
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+                if ( active_w )
+#else
                 if ( hMdDec->spar_md_cfg.active_w )
+#endif
                 {
                     if ( dtx_vad == 0 )
                     {
@@ -3360,8 +3447,13 @@ void ivas_spar_to_dirac(
     /* DirAC MD averaged over 4 subframes and converted to SPAR format similar to encoder processing */
     if ( hMdDec->spar_md_cfg.nchan_transport > 1 )
     {
-        ivas_get_spar_md_from_dirac( azi_dirac, ele_dirac, diffuseness, 1, NULL, &hMdDec->spar_md, &hMdDec->spar_md_cfg,
-                                     end_band, num_bands_out, ( hMdDec->spar_hoa_md_flag ) ? 1 : sba_order_internal, dtx_vad, NULL, st_ivas->hQMetaData->useLowerRes, active_w_vlbr );
+        ivas_get_spar_md_from_dirac( azi_dirac, ele_dirac, diffuseness, 1, NULL, &hMdDec->spar_md, &hMdDec->spar_md_cfg, end_band, num_bands_out, ( hMdDec->spar_hoa_md_flag ) ? 1 : sba_order_internal, dtx_vad, NULL,
+                                     st_ivas->hQMetaData->useLowerRes, active_w_vlbr
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+                                     ,
+                                     dyn_active_w_flag
+#endif
+        );
 
         /* temporarily copy frame-wise prediction coefficients in DirAC bands*/
         for ( pred_idx = 0; pred_idx < FOA_CHANNELS - 1; pred_idx++ )
@@ -3382,7 +3474,12 @@ void ivas_spar_to_dirac(
 #endif
     );
     ivas_get_spar_md_from_dirac( azi_dirac, ele_dirac, diffuseness, num_md_sub_frames, NULL, &hMdDec->spar_md, &hMdDec->spar_md_cfg,
-                                 end_band, num_bands_out / bw, ( hMdDec->spar_hoa_md_flag ) ? 1 : sba_order_internal, dtx_vad, NULL, st_ivas->hQMetaData->useLowerRes, active_w_vlbr );
+                                 end_band, num_bands_out / bw, ( hMdDec->spar_hoa_md_flag ) ? 1 : sba_order_internal, dtx_vad, NULL, st_ivas->hQMetaData->useLowerRes, active_w_vlbr
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+                                 ,
+                                 dyn_active_w_flag
+#endif
+    );
 #else
 
     num_subframes = MAX_PARAM_SPATIAL_SUBFRAMES;
@@ -3392,7 +3489,12 @@ void ivas_spar_to_dirac(
     }
 
     ivas_get_spar_md_from_dirac( azi_dirac, ele_dirac, diffuseness, num_subframes, NULL, &hMdDec->spar_md, &hMdDec->spar_md_cfg,
-                                 end_band, num_bands_out / bw, ( hMdDec->spar_hoa_md_flag ) ? 1 : sba_order_internal, dtx_vad, NULL, st_ivas->hQMetaData->useLowerRes, active_w_vlbr );
+                                 end_band, num_bands_out / bw, ( hMdDec->spar_hoa_md_flag ) ? 1 : sba_order_internal, dtx_vad, NULL, st_ivas->hQMetaData->useLowerRes, active_w_vlbr
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+                                 ,
+                                 dyn_active_w_flag
+#endif
+    );
 #endif
     if ( st_ivas->hQMetaData->useLowerRes && dtx_vad )
     {
diff --git a/lib_enc/ivas_enc_cov_handler.c b/lib_enc/ivas_enc_cov_handler.c
index fcf2efc6c293b5e8fd24ec16342dabff6ea2e153..5b9ab2801cfb779ae0954f0bce5415f80b26c02e 100644
--- a/lib_enc/ivas_enc_cov_handler.c
+++ b/lib_enc/ivas_enc_cov_handler.c
@@ -107,6 +107,11 @@ ivas_error ivas_spar_covar_enc_open(
     hCovState->num_bins = (int16_t) ( input_Fs / FRAMES_PER_SEC );
     hCovState->prior_dtx_present = 0;
 
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+    set_zero( hCovState->bb_var_lt, FOA_CHANNELS );
+    hCovState->prior_var_flag = -1;
+#endif
+
     *hCovEnc = hCovState;
 
     return error;
@@ -143,6 +148,119 @@ void ivas_spar_covar_enc_close(
 }
 
 
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+/*-----------------------------------------------------------------------------------------*
+ * Function ivas_spar_get_activeW_flag()
+ *
+ *
+ *-----------------------------------------------------------------------------------------*/
+int16_t ivas_spar_get_activeW_flag(
+    ivas_enc_cov_handler_state_t *hCovEnc,
+    float *cov_real[IVAS_SPAR_MAX_CH][IVAS_SPAR_MAX_CH],
+    float *cov_dtx_real[IVAS_SPAR_MAX_CH][IVAS_SPAR_MAX_CH],
+    const int16_t dtx_vad,
+    const int16_t nchan_inp,
+    const int16_t nchan_transport,
+    int16_t *res_ind,
+    const int16_t *dmx_order )
+{
+    int16_t b, ch, num_bands, num_chs, activeW_flag;
+    float bb_var[FOA_CHANNELS], sm_fact, side_ch_var, en_ratio;
+    num_chs = min( nchan_inp, FOA_CHANNELS );
+    num_bands = ivas_get_num_bands_from_bw_idx( SPAR_CONFIG_BW );
+
+    set_zero( bb_var, FOA_CHANNELS );
+
+    if ( dtx_vad == 1 )
+    {
+        for ( ch = 0; ch < num_chs; ch++ )
+        {
+            for ( b = 0; b < num_bands; b++ )
+            {
+                bb_var[ch] += cov_real[ch][ch][b];
+            }
+        }
+    }
+    else
+    {
+        for ( ch = 0; ch < num_chs; ch++ )
+        {
+            for ( b = 0; b < num_bands; b++ )
+            {
+                bb_var[ch] += cov_dtx_real[ch][ch][b];
+            }
+        }
+    }
+
+    if ( hCovEnc->prior_var_flag == -1 )
+    {
+        for ( ch = 0; ch < num_chs; ch++ )
+        {
+            hCovEnc->bb_var_lt[ch] = bb_var[ch];
+        }
+        // hCovEnc->prior_var_flag = 0;
+    }
+    else
+    {
+        sm_fact = 0.5f;
+        for ( ch = 0; ch < num_chs; ch++ )
+        {
+            hCovEnc->bb_var_lt[ch] = sm_fact * hCovEnc->bb_var_lt[ch] + ( 1 - sm_fact ) * bb_var[ch];
+        }
+    }
+
+    side_ch_var = 0.0f;
+    for ( ch = nchan_transport; ch < num_chs; ch++ )
+    {
+        side_ch_var += hCovEnc->bb_var_lt[dmx_order[ch]];
+    }
+
+    if ( side_ch_var < ( IVAS_SPAR_SIDE_CH_DYN_ACTIVEW_THRESH * IVAS_SPAR_SIDE_CH_DYN_ACTIVEW_THRESH ) )
+    {
+        activeW_flag = 0;
+    }
+    else
+    {
+        en_ratio = hCovEnc->bb_var_lt[0] / side_ch_var;
+        if ( en_ratio < ( IVAS_SPAR_DYN_ACTIVEW_THRESH * IVAS_SPAR_DYN_ACTIVEW_THRESH ) )
+        {
+            activeW_flag = 1;
+        }
+        else
+        {
+            activeW_flag = 0;
+        }
+    }
+
+    if ( activeW_flag )
+    {
+        *res_ind = 0;
+        if ( nchan_transport == 2 )
+        {
+            int16_t max_idx;
+            float max_val;
+            max_idx = nchan_transport;
+            max_val = hCovEnc->bb_var_lt[max_idx];
+            for ( ch = nchan_transport + 1; ch < num_chs; ch++ )
+            {
+                if ( hCovEnc->bb_var_lt[ch] > max_val )
+                {
+                    max_idx = ch;
+                    max_val = hCovEnc->bb_var_lt[ch];
+                }
+            }
+            *res_ind = max_idx;
+        }
+        else if ( nchan_transport == 3 )
+        {
+            *res_ind = dmx_order[nchan_transport];
+        }
+    }
+
+    return activeW_flag;
+}
+#endif
+
 /*-----------------------------------------------------------------------------------------*
  * Function ivas_enc_cov_handler_process()
  *
@@ -161,7 +279,17 @@ void ivas_enc_cov_handler_process(
     const int16_t num_ch,
     const int16_t dtx_vad,
     const int16_t transient_det[2],
-    const int16_t HOA_md_ind[IVAS_SPAR_MAX_CH] )
+    const int16_t HOA_md_ind[IVAS_SPAR_MAX_CH]
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+    ,
+    int16_t *res_ind,
+    const int16_t *remix_order,
+    int16_t *dyn_active_w_flag,
+    const int16_t nchan_transport,
+    const int16_t is_sba
+#endif
+
+)
 {
     int16_t i, j;
     int16_t dtx_cov_flag;
@@ -177,6 +305,22 @@ void ivas_enc_cov_handler_process(
                    cov_real,
                    HOA_md_ind );
 
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+    if ( is_sba )
+    {
+        *res_ind = 0;
+        if ( nchan_transport > 1 && nchan_transport <= ( FOA_CHANNELS - 1 ) )
+        {
+            *dyn_active_w_flag = ivas_spar_get_activeW_flag( hCovEnc, cov_real, cov_real, dtx_vad, num_ch, nchan_transport, res_ind,
+                                                             remix_order );
+        }
+        else
+        {
+            *dyn_active_w_flag = 0;
+        }
+    }
+#endif
+
 #ifdef DEBUG_SPAR_WRITE_OUT_COV
     {
         static FILE *fid = 0;
diff --git a/lib_enc/ivas_mc_paramupmix_enc.c b/lib_enc/ivas_mc_paramupmix_enc.c
index 5c50c3d6bdd6946ff42c6dca80a34e953cf3fbc2..8c442a51c6d357c9d6dc597992901dc90da299aa 100644
--- a/lib_enc/ivas_mc_paramupmix_enc.c
+++ b/lib_enc/ivas_mc_paramupmix_enc.c
@@ -821,7 +821,12 @@ static void ivas_mc_paramupmix_param_est_enc(
             }
         }
 
-        ivas_enc_cov_handler_process( hMCParamUpmix->hCovEnc[b], pp_in_fr_real, pp_in_fr_imag, cov_real, cov_dtx_real, hMCParamUpmix->hFbMixer->pFb, 0, hMCParamUpmix->hFbMixer->pFb->filterbank_num_bands, MC_PARAMUPMIX_NCH, 0 /*dtx_vad*/, transient_det[b], HOA_md_ind );
+        ivas_enc_cov_handler_process( hMCParamUpmix->hCovEnc[b], pp_in_fr_real, pp_in_fr_imag, cov_real, cov_dtx_real, hMCParamUpmix->hFbMixer->pFb, 0, hMCParamUpmix->hFbMixer->pFb->filterbank_num_bands, MC_PARAMUPMIX_NCH, 0 /*dtx_vad*/, transient_det[b], HOA_md_ind
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+                                      ,
+                                      NULL, NULL, NULL, 0, 0
+#endif
+        );
     }
     maxbands = hMCParamUpmix->hFbMixer->pFb->filterbank_num_bands;
     for ( b = 0; b < MC_PARAMUPMIX_COMBINATIONS; b++ )
diff --git a/lib_enc/ivas_spar_encoder.c b/lib_enc/ivas_spar_encoder.c
index 516104c79b8ef60eb0582b094e1fe08c27d48367..2b09d00b42e9a614545c26c04d96660c949e0ae0 100644
--- a/lib_enc/ivas_spar_encoder.c
+++ b/lib_enc/ivas_spar_encoder.c
@@ -386,7 +386,13 @@ static ivas_error ivas_spar_cov_md_process(
     float *ppIn_FR_real[IVAS_SPAR_MAX_CH],
     float *ppIn_FR_imag[IVAS_SPAR_MAX_CH],
     const int16_t transient_det[2],
-    const int16_t dtx_vad )
+    const int16_t dtx_vad
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+    ,
+    const int16_t nchan_transport,
+    int16_t *dyn_active_w_flag
+#endif
+)
 {
     int16_t i, j, i_ts, b, table_idx;
     int16_t active_w_vlbr;
@@ -443,7 +449,34 @@ static ivas_error ivas_spar_cov_md_process(
         }
     }
 
-    ivas_enc_cov_handler_process( hSpar->hCovEnc, ppIn_FR_real, ppIn_FR_imag, cov_real, cov_dtx_real, hSpar->hFbMixer->pFb, 0, hSpar->hFbMixer->pFb->filterbank_num_bands, nchan_inp, dtx_vad, transient_det, hSpar->hMdEnc->HOA_md_ind );
+    ivas_enc_cov_handler_process( hSpar->hCovEnc, ppIn_FR_real, ppIn_FR_imag, cov_real, cov_dtx_real, hSpar->hFbMixer->pFb, 0, hSpar->hFbMixer->pFb->filterbank_num_bands, nchan_inp, dtx_vad, transient_det, hSpar->hMdEnc->HOA_md_ind
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+                                  ,
+                                  &hSpar->hMdEnc->spar_md.res_ind,
+                                  remix_order_set[hSpar->hMdEnc->spar_md_cfg.remix_unmix_order],
+                                  dyn_active_w_flag, nchan_transport, 1
+
+#endif
+    );
+
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+    if ( nchan_transport > 1 && nchan_transport <= ( FOA_CHANNELS - 1 ) )
+    {
+        push_next_indice( hMetaData, *dyn_active_w_flag, 1 );
+        if ( ( *dyn_active_w_flag == 1 ) && ( nchan_transport == 2 ) )
+        {
+            push_next_indice( hMetaData, hSpar->hMdEnc->spar_md.res_ind - nchan_transport, 1 );
+        }
+        hSpar->front_vad_flag = ( *dyn_active_w_flag == 1 ) ? 1 : hSpar->front_vad_flag;
+    }
+    else
+    {
+        if ( nchan_transport == FOA_CHANNELS )
+        {
+            push_next_indice( hMetaData, 0, 1 );
+        }
+    }
+#endif
 
     /*-----------------------------------------------------------------------------------------*
      * MetaData encoder
@@ -452,6 +485,10 @@ static ivas_error ivas_spar_cov_md_process(
     if ( hSpar->hMdEnc->spar_hoa_md_flag == 0 )
     {
         ivas_spar_md_enc_process( hSpar->hMdEnc, hEncoderConfig, cov_real, cov_dtx_real, hMetaData, dtx_vad, nchan_inp, sba_order, hSpar->hFbMixer->prior_mixer
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+                                  ,
+                                  *dyn_active_w_flag
+#endif
 #ifdef FIX_527_SBA_MONO_INPUT
                                   ,
                                   hQMetaData->dirac_mono_flag
@@ -499,12 +536,21 @@ static ivas_error ivas_spar_cov_md_process(
             Wscale_d[b] = min( 2.0f, max( Wscale_d[b], 1.0f ) );
         }
 
-        ivas_get_spar_md_from_dirac( azi_dirac, ele_dirac, diffuseness, 1, hSpar->hMdEnc->mixer_mat, &hSpar->hMdEnc->spar_md, &hSpar->hMdEnc->spar_md_cfg, d_start_band, d_end_band, ( hSpar->hMdEnc->spar_hoa_md_flag ) ? 1 : sba_order, dtx_vad, Wscale_d, hQMetaData->useLowerRes, active_w_vlbr );
+        ivas_get_spar_md_from_dirac( azi_dirac, ele_dirac, diffuseness, 1, hSpar->hMdEnc->mixer_mat, &hSpar->hMdEnc->spar_md, &hSpar->hMdEnc->spar_md_cfg, d_start_band, d_end_band, ( hSpar->hMdEnc->spar_hoa_md_flag ) ? 1 : sba_order, dtx_vad, Wscale_d, hQMetaData->useLowerRes, active_w_vlbr
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+                                     ,
+                                     *dyn_active_w_flag
+#endif
+        );
     }
 
     if ( hSpar->hMdEnc->spar_hoa_md_flag )
     {
         ivas_spar_md_enc_process( hSpar->hMdEnc, hEncoderConfig, cov_real, cov_dtx_real, hMetaData, dtx_vad, nchan_inp, sba_order, hSpar->hFbMixer->prior_mixer
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+                                  ,
+                                  *dyn_active_w_flag
+#endif
 #ifdef FIX_527_SBA_MONO_INPUT
                                   ,
                                   hQMetaData->dirac_mono_flag
@@ -556,6 +602,9 @@ static ivas_error ivas_spar_enc_process(
 
     float *ppIn_FR_real[IVAS_SPAR_MAX_CH], *ppIn_FR_imag[IVAS_SPAR_MAX_CH];
     float wyzx_del_buf[FOA_CHANNELS][IVAS_FB_1MS_48K_SAMP];
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+    int16_t dyn_active_w_flag;
+#endif
     int16_t nchan_fb_in;
 
     /* ToDo: Commented for now*/
@@ -609,7 +658,11 @@ static ivas_error ivas_spar_enc_process(
     if ( hSpar->hFbMixer->fb_cfg->active_w_mixing == 0 )
     {
         /* fill delay (1 ms) buffer for all Transport channels */
+#ifndef FIX_SBA_VANISHING_RESIDUAL
         for ( i = 0; i < hSpar->hFbMixer->fb_cfg->num_out_chans; i++ )
+#else
+        for ( i = 0; i < FOA_CHANNELS; i++ )
+#endif
         {
             int16_t idx = hSpar->hFbMixer->fb_cfg->remix_order[i];
             mvr2r( &hSpar->hFbMixer->ppFilterbank_prior_input[idx][hSpar->hFbMixer->fb_cfg->prior_input_length - num_del_samples], wyzx_del_buf[idx], num_del_samples );
@@ -689,7 +742,13 @@ static ivas_error ivas_spar_enc_process(
      * Covariance and MD processing
      *-----------------------------------------------------------------------------------------*/
 
-    if ( ( error = ivas_spar_cov_md_process( hEncoderConfig, st_ivas->hSpar, st_ivas->hQMetaData, hMetaData, nchan_inp, sba_order, ppIn_FR_real, ppIn_FR_imag, transient_det, dtx_vad ) ) != IVAS_ERR_OK )
+    if ( ( error = ivas_spar_cov_md_process( hEncoderConfig, st_ivas->hSpar, st_ivas->hQMetaData, hMetaData, nchan_inp, sba_order, ppIn_FR_real, ppIn_FR_imag, transient_det, dtx_vad
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+                                             ,
+                                             nchan_transport,
+                                             &dyn_active_w_flag
+#endif
+                                             ) ) != IVAS_ERR_OK )
     {
         return error;
     }
@@ -729,9 +788,35 @@ static ivas_error ivas_spar_enc_process(
         }
     }
 
-    ivas_enc_cov_handler_process( hSpar->hCovEnc, ppIn_FR_real, ppIn_FR_imag, cov_real, cov_dtx_real, hSpar->hFbMixer->pFb, 0, hSpar->hFbMixer->pFb->filterbank_num_bands, nchan_inp, dtx_vad, transient_det, hSpar->hMdEnc->HOA_md_ind );
+    ivas_enc_cov_handler_process( hSpar->hCovEnc, ppIn_FR_real, ppIn_FR_imag, cov_real, cov_dtx_real, hSpar->hFbMixer->pFb, 0, hSpar->hFbMixer->pFb->filterbank_num_bands, nchan_inp, dtx_vad, transient_det, hSpar->hMdEnc->HOA_md_ind
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+                                  ,
+                                  &hSpar->hMdEnc->spar_md.res_ind,
+                                  remix_order_set[hSpar->hMdEnc->spar_md_cfg.remix_unmix_order],
+                                  &dyn_active_w_flag, st_ivas->nchan_transport, 1
+
+#endif
+    );
 
     nchan_transport = st_ivas->nchan_transport;
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+    if ( nchan_transport > 1 && nchan_transport <= ( FOA_CHANNELS - 1 ) )
+    {
+        push_next_indice( hMetaData, dyn_active_w_flag, 1 );
+        if ( ( dyn_active_w_flag == 1 ) && ( nchan_transport == 2 ) )
+        {
+            push_next_indice( hMetaData, hSpar->hMdEnc->spar_md.res_ind - nchan_transport, 1 );
+        }
+        st_ivas->hSpar->front_vad_flag = ( dyn_active_w_flag == 1 ) ? 1 : st_ivas->hSpar->front_vad_flag;
+    }
+    else
+    {
+        if ( nchan_transport == FOA_CHANNELS )
+        {
+            push_next_indice( hMetaData, 0, 1 );
+        }
+    }
+#endif
 
     /*-----------------------------------------------------------------------------------------*
      * MetaData encoder
@@ -740,6 +825,10 @@ static ivas_error ivas_spar_enc_process(
     if ( hSpar->hMdEnc->spar_hoa_md_flag == 0 )
     {
         ivas_spar_md_enc_process( hSpar->hMdEnc, hEncoderConfig, cov_real, cov_dtx_real, hMetaData, dtx_vad, nchan_inp, sba_order, hSpar->hFbMixer->prior_mixer
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+                                  ,
+                                  dyn_active_w_flag
+#endif
 #ifdef FIX_527_SBA_MONO_INPUT
                                   ,
                                   hQMetaData->dirac_mono_flag
@@ -787,12 +876,22 @@ static ivas_error ivas_spar_enc_process(
             Wscale_d[b] = min( 2.0f, max( Wscale_d[b], 1.0f ) );
         }
 
-        ivas_get_spar_md_from_dirac( azi_dirac, ele_dirac, diffuseness, 1, hSpar->hMdEnc->mixer_mat, &hSpar->hMdEnc->spar_md, &hSpar->hMdEnc->spar_md_cfg, d_start_band, d_end_band, ( hSpar->hMdEnc->spar_hoa_md_flag ) ? 1 : sba_order, dtx_vad, Wscale_d, hQMetaData->useLowerRes, active_w_vlbr );
+        ivas_get_spar_md_from_dirac( azi_dirac, ele_dirac, diffuseness, 1, hSpar->hMdEnc->mixer_mat, &hSpar->hMdEnc->spar_md, &hSpar->hMdEnc->spar_md_cfg, d_start_band, d_end_band, ( hSpar->hMdEnc->spar_hoa_md_flag ) ? 1 : sba_order, dtx_vad, Wscale_d,
+                                     hQMetaData->useLowerRes, active_w_vlbr
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+                                     ,
+                                     dyn_active_w_flag
+#endif
+        );
     }
 
     if ( hSpar->hMdEnc->spar_hoa_md_flag )
     {
         ivas_spar_md_enc_process( hSpar->hMdEnc, hEncoderConfig, cov_real, cov_dtx_real, hMetaData, dtx_vad, nchan_inp, sba_order, hSpar->hFbMixer->prior_mixer
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+                                  ,
+                                  dyn_active_w_flag
+#endif
 #ifdef FIX_527_SBA_MONO_INPUT
                                   ,
                                   hQMetaData->dirac_mono_flag
@@ -916,9 +1015,44 @@ static ivas_error ivas_spar_enc_process(
 #endif
     if ( hSpar->hFbMixer->fb_cfg->active_w_mixing == 0 )
     {
-        /* delayed W */
-        mvr2r( wyzx_del_buf[0], p_pcm_tmp[0], num_del_samples );
-        mvr2r( data_f[0], p_pcm_tmp[0] + num_del_samples, input_frame - num_del_samples );
+
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+        /*cross fade between new active W channels and old passive W channel*/
+        if ( dyn_active_w_flag == 1 )
+        {
+            if ( hSpar->hMdEnc->spar_md.prior_dyn_active_w_flag != dyn_active_w_flag )
+            {
+                float new_w[L_FRAME48k];
+
+                /* delayed W */
+                mvr2r( wyzx_del_buf[0], p_pcm_tmp[0], num_del_samples );
+                mvr2r( data_f[0], p_pcm_tmp[0] + num_del_samples, input_frame - num_del_samples );
+
+                mvr2r( wyzx_del_buf[hSpar->hMdEnc->spar_md.res_ind], new_w, num_del_samples );
+                mvr2r( data_f[hSpar->hMdEnc->spar_md.res_ind], &new_w[num_del_samples], input_frame - num_del_samples );
+
+                if ( hSpar->hMdEnc->spar_md.prior_dyn_active_w_flag == 0 && dyn_active_w_flag == 1 )
+                {
+                    ivas_fb_mixer_cross_fading( hSpar->hFbMixer, p_pcm_tmp, p_pcm_tmp[0], new_w, 0, input_frame, 0 );
+                }
+                else if ( hSpar->hMdEnc->spar_md.prior_dyn_active_w_flag == 1 && dyn_active_w_flag == 0 )
+                {
+                    ivas_fb_mixer_cross_fading( hSpar->hFbMixer, p_pcm_tmp, new_w, p_pcm_tmp[0], 0, input_frame, 0 );
+                }
+            }
+            else
+            {
+                mvr2r( wyzx_del_buf[hSpar->hMdEnc->spar_md.res_ind], p_pcm_tmp[0], num_del_samples );
+                mvr2r( data_f[hSpar->hMdEnc->spar_md.res_ind], p_pcm_tmp[0] + num_del_samples, input_frame - num_del_samples );
+            }
+        }
+        else
+#endif
+        {
+            /* delayed W */
+            mvr2r( wyzx_del_buf[0], p_pcm_tmp[0], num_del_samples );
+            mvr2r( data_f[0], p_pcm_tmp[0] + num_del_samples, input_frame - num_del_samples );
+        }
 
         for ( i = 1; i < hSpar->hFbMixer->fb_cfg->num_out_chans; i++ )
         {
@@ -985,6 +1119,7 @@ static ivas_error ivas_spar_enc_process(
         {
             ivas_agc_enc_process( hSpar->hAgcEnc, hMetaData, p_pcm_tmp, p_pcm_tmp, hSpar->hFbMixer->fb_cfg->num_out_chans, hEncoderConfig );
         }
+#ifndef FIX_SBA_VANISHING_RESIDUAL
         else
         {
             /* IVAS_fmToDo: This AGC on/off bit should be removed when the command line option to force enable/disable AGC is
@@ -993,6 +1128,7 @@ static ivas_error ivas_spar_enc_process(
              * ivas_agc_enc_get_flag function should be moved to ivas_agc_com.c and renamed when this occurs. */
             push_next_indice( hMetaData, 0, 1 );
         }
+#endif
     }
 #ifdef DEBUG_SBA_AUDIO_DUMP
     /* Dump audio signal after ivas_agc_enc_process */
@@ -1043,13 +1179,26 @@ static ivas_error ivas_spar_enc_process(
 
     for ( j = 0; j < nchan_transport; j++ )
     {
-        mvr2r( p_pcm_tmp[j], data_f[order[j]], input_frame );
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+        if ( st_ivas->nchan_transport < 3 )
+        {
+            mvr2r( p_pcm_tmp[j], data_f[j], input_frame );
+        }
+        else
+#endif
+        {
+            mvr2r( p_pcm_tmp[j], data_f[order[j]], input_frame );
+        }
     }
     for ( ; j < IVAS_SPAR_MAX_DMX_CHS; j++ )
     {
         set_f( data_f[order[j]], 0.0f, input_frame );
     }
 
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+    hSpar->hMdEnc->spar_md.prior_dyn_active_w_flag = dyn_active_w_flag;
+#endif
+
     pop_wmops();
 
     /* ToDo: Commented for now */
diff --git a/lib_enc/ivas_spar_md_enc.c b/lib_enc/ivas_spar_md_enc.c
index 4e8556cd3789ea7e79d0140dbb5ca609939f0a6e..6b7da65f2cb571675d19fbd1d17b856176038804 100644
--- a/lib_enc/ivas_spar_md_enc.c
+++ b/lib_enc/ivas_spar_md_enc.c
@@ -332,6 +332,10 @@ ivas_error ivas_spar_md_enc_init(
     ivas_sba_get_spar_hoa_ch_ind( num_channels, hEncoderConfig->ivas_total_brate, hMdEnc->HOA_md_ind );
     table_idx = ivas_get_spar_table_idx( hEncoderConfig->ivas_total_brate, sba_order, SPAR_CONFIG_BW, NULL, NULL );
 
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+    hMdEnc->spar_md.prior_dyn_active_w_flag = 0;
+#endif
+
     ivas_spar_set_bitrate_config( &hMdEnc->spar_md_cfg, table_idx, ( hMdEnc->spar_hoa_md_flag ) ? IVAS_MAX_NUM_BANDS : SPAR_DIRAC_SPLIT_START_BAND,
                                   hMdEnc->spar_hoa_dirac2spar_md_flag, 1, hEncoderConfig->Opt_PCA_ON,
 #ifndef DEBUG_AGC_ENCODER_CMD_OPTION
@@ -567,9 +571,13 @@ ivas_error ivas_spar_md_enc_process(
     const int16_t nchan_inp,
     const int16_t sba_order,                                                   /* i  : Ambisonic (SBA) order       */
     float *prior_mixer[IVAS_MAX_FB_MIXER_OUT_CH][IVAS_MAX_SPAR_FB_MIXER_IN_CH] /* i  : prior mixer_matrix     */
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+    ,
+    const int16_t dyn_active_w_flag /* i : flag to indicate dynamic active W*/
+#endif
 #ifdef FIX_527_SBA_MONO_INPUT
     ,
-    const int16_t dirac_mono_flag
+    const int16_t dirac_mono_flag /* i : flag to indicate mono only mode in SBA*/
 #endif
 )
 {
@@ -601,7 +609,11 @@ ivas_error ivas_spar_md_enc_process(
 
     num_quant_strats = hMdEnc->spar_md_cfg.num_quant_strats;
     num_ch = ivas_sba_get_nchan_metadata( sba_order, hEncoderConfig->ivas_total_brate );
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+    active_w = ( hMdEnc->spar_md_cfg.active_w == 1 ) || ( dyn_active_w_flag == 1 );
+#else
     active_w = hMdEnc->spar_md_cfg.active_w;
+#endif
     nchan_transport = hMdEnc->spar_md_cfg.nchan_transport;
 
     bwidth = ivas_get_bw_idx_from_sample_rate( hEncoderConfig->input_Fs );
@@ -692,7 +704,12 @@ ivas_error ivas_spar_md_enc_process(
     ivas_compute_spar_params( cov_real, dm_fv_re, 0, hMdEnc->mixer_mat, 0, nB, dtx_vad, num_ch,
                               bands_bw, active_w,
                               active_w_vlbr,
-                              &hMdEnc->spar_md_cfg, &hMdEnc->spar_md, Wscale, 0 );
+                              &hMdEnc->spar_md_cfg, &hMdEnc->spar_md, Wscale, 0
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+                              ,
+                              dyn_active_w_flag
+#endif
+    );
 
 #ifdef FIX_527_SBA_MONO_INPUT
     if ( dirac_mono_flag )
@@ -778,7 +795,12 @@ ivas_error ivas_spar_md_enc_process(
 
                 if ( ndm != num_ch )
                 {
-                    ivas_calc_c_p_coeffs( &hMdEnc->spar_md, cov_real, 0, hMdEnc->mixer_mat_local, num_ch, ndm, b, dtx_vad, 1, planarCP );
+                    ivas_calc_c_p_coeffs( &hMdEnc->spar_md, cov_real, 0, hMdEnc->mixer_mat_local, num_ch, ndm, b, dtx_vad, 1, planarCP
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+                                          ,
+                                          dyn_active_w_flag
+#endif
+                    );
                 }
             }
         }
@@ -927,6 +949,10 @@ ivas_error ivas_spar_md_enc_process(
 #ifndef FIX_280_PLANAR_CP
                                       ,
                                       planarCP
+#endif
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+                                      ,
+                                      dyn_active_w_flag
 #endif
                 );
 #ifdef FIX_527_SBA_MONO_INPUT
@@ -2136,6 +2162,12 @@ static void ivas_write_parameter_bitstream_dtx(
     sid_bits_len = hMetaData->nb_bits_tot - sid_bits_len;
     zero_pad_bits = ( SPAR_DTX_BANDS * SPAR_SID_BITS_TAR_PER_BAND ) - sid_bits_len;
     assert( zero_pad_bits >= 0 );
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+    if ( num_dmx[0] == 2 )
+    {
+        zero_pad_bits -= 1;
+    }
+#endif
     while ( zero_pad_bits > 0 )
     {
         j = min( zero_pad_bits, 16 );
diff --git a/lib_enc/ivas_stat_enc.h b/lib_enc/ivas_stat_enc.h
index e9f7d34736702c0d200331c83be5a3eaaa854d42..516604fc7235f13d862d4cbf79ada80b2365e0d7 100644
--- a/lib_enc/ivas_stat_enc.h
+++ b/lib_enc/ivas_stat_enc.h
@@ -651,7 +651,10 @@ typedef struct ivas_enc_cov_handler_state_t
     ivas_cov_smooth_state_t *pCov_dtx_state;
     int16_t num_bins;
     int16_t prior_dtx_present;
-
+#ifdef FIX_SBA_VANISHING_RESIDUAL
+    float bb_var_lt[FOA_CHANNELS];
+    int16_t prior_var_flag;
+#endif
 } ivas_enc_cov_handler_state_t;
 
 
diff --git a/tests/codec_be_on_mr_selection/__init__.py b/tests/codec_be_on_mr_selection/__init__.py
index da1d8c35785275ca34c6c4bde6eee5f39cf26fe0..14f0bb0b1786eab41c0f22b293d8dc7ecee5689b 100644
--- a/tests/codec_be_on_mr_selection/__init__.py
+++ b/tests/codec_be_on_mr_selection/__init__.py
@@ -127,6 +127,7 @@ def run_check(
     is_ref_creation,
     input_file_num=None,
     keep_files=True,
+    compare_bitstream=False,
 ):
     sampling_rate = 48
     output_mode, options = OUTPUT_MODES_AND_OPTIONS_FOR_EXPERIMENT[experiment]
@@ -162,8 +163,9 @@ def run_check(
     )
 
     if not is_ref_creation:
-        if not is_be_to_ref(dut_bitstream):
-            pytest.fail(f"Bitstream file differs from reference")
+        if compare_bitstream:
+            if not is_be_to_ref(dut_bitstream):
+                pytest.fail(f"Bitstream file differs from reference")
 
     dut_bitstream_to_decoder = dut_bitstream
     if error_pattern is not None:
diff --git a/tests/codec_be_on_mr_selection/test_experiments.py b/tests/codec_be_on_mr_selection/test_experiments.py
index 5b2f51689342117c2e543442a974bce6714ff6fc..53fdd8eba9e18d59fead99844a287f336423a2c3 100644
--- a/tests/codec_be_on_mr_selection/test_experiments.py
+++ b/tests/codec_be_on_mr_selection/test_experiments.py
@@ -53,6 +53,7 @@ def test_p800(
     dut_decoder_frontend,
     update_ref,
     keep_files,
+    compare_bitstream,
 ):
     run_check(
         experiment,
@@ -65,6 +66,7 @@ def test_p800(
         dut_decoder_frontend,
         update_ref == 1,
         keep_files=keep_files,
+        compare_bitstream=compare_bitstream,
     )
 
 
@@ -82,6 +84,7 @@ def test_bs1534_no_masa(
     dut_decoder_frontend,
     update_ref,
     keep_files,
+    compare_bitstream,
 ):
     category = ""
     run_check(
@@ -96,6 +99,7 @@ def test_bs1534_no_masa(
         update_ref == 1,
         input_file_num=input_file_num,
         keep_files=keep_files,
+        compare_bitstream=compare_bitstream,
     )
 
 
@@ -116,6 +120,7 @@ def test_bs1534_masa(
     dut_decoder_frontend,
     update_ref,
     keep_files,
+    compare_bitstream,
 ):
     run_check(
         experiment,
@@ -129,4 +134,5 @@ def test_bs1534_masa(
         update_ref == 1,
         input_file_num=input_file_num,
         keep_files=keep_files,
+        compare_bitstream=compare_bitstream,
     )
diff --git a/tests/conftest.py b/tests/conftest.py
index e4de453b0ea6698f9600076ded65a53a1a2b7d51..ac1b37121af50d3ba529766cc0ee4eb75b4b9227 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -132,6 +132,14 @@ def pytest_addoption(parser):
         help="By default, the DUT output files of successful tests are deleted."
         " Use --keep_files to prevent these deletions.",
     )
+    
+    parser.addoption(
+        "--compare_bitstream",
+        action="store_true",
+        help="By default, the IVAS encoded bitstream is not compared with ref."
+        " Use --compare_bitstream to compare IVAS encoded bitstream.",
+    )
+    
 
     parser.addoption(
         "--selection_be_md5_file",
@@ -158,6 +166,12 @@ def keep_files(request) -> bool:
     """
     return request.config.option.keep_files
 
+@pytest.fixture(scope="session")
+def compare_bitstream(request) -> bool:
+    """
+    Return indication to compare IVAS encoded bitstream.
+    """
+    return request.config.option.compare_bitstream
 
 @pytest.fixture(scope="session")
 def dut_encoder_path(request) -> str: