lib_com/options.h

@@ -93,6 +93,7 @@
 #define FIX_1996_MASKING_NOISE                               /* Dlb: Heavy precision loss in ola buffers causing discontinuity*/
 #define FIX1998_APA_EXEC_SCALING                             /* FhG: fix scaling of apa_exec_ivas_fx(); avoid continuously worse scaling with previous data */
 #define FIX2007_BASSPSFILTER_OVERFLOW                        /* FhG: use saturing operator, to avoid overflow in bass_psfilter_fx() */
+#define FIX_ISSUE_2004_LPC_SHB_SAT                           /* Dolby: Issue 2004: prevent saturation of the LPC SHB filter */
 
 #define FIX_2009_HIGH_NOISE_FLOOR_FOR_FX_DEC                 /* FhG: Corrected the q_input in the input of generate_masking_noise_dirac_ivas_fx() */
 /* #################### Start BASOP porting switches ############################ */

lib_enc/swb_tbe_enc_fx.c

@@ -3161,7 +3161,25 @@ void swb_tbe_enc_ivas_fx(
         enerG = Enr_1_Az_fx( lpc_shb1, 2 * L_SUBFR ); /* Q3 */
 
         /* if the LP gain is greater than a threshold, avoid saturation */
+#ifdef FIX_ISSUE_2004_LPC_SHB_SAT
+        Word16 flag_sat = 0;
+        Word16 lpc_shb_fx0_req_shift = sub( norm_s( lpc_shb_fx[0] ), 2 );
+        IF( GT_16( lpc_shb_fx0_req_shift, 0 ) )
+        {
+            FOR( i = 1; i <= LPC_SHB_ORDER; i++ )
+            {
+                IF( LT_16( norm_s( lpc_shb_fx[i] ), lpc_shb_fx0_req_shift ) )
+                {
+                    flag_sat = 1;
+                    break;
+                }
+            }
+        }
+
+        IF( GT_16( enerG, 256 /* 32.0 in Q3 */ ) || flag_sat )
+#else
         IF( GT_16( enerG, 256 /*32 Q3*/ ) )
+#endif
         {
             set16_fx( lpc_shb_fx, 0, LPC_SHB_ORDER + 1 );
             E_LPC_lev_dur( R_h, R_l, lpc_shb_fx, LepsP, 2, NULL ); /* LPC in Q14 */