Line data    Source code

       1             : /*====================================================================================
       2             :     EVS Codec 3GPP TS26.452 Aug 12, 2021. Version 16.3.0
       3             :   ====================================================================================*/
       4             : 
       5             : #include "options.h" /* Compilation switches                   */
       6             : #include "cnst.h"    /* Common constants                       */
       7             : //#include "prot_fx.h"    /* Function prototypes                    */
       8             : #include "prot_fx.h"     /* Function prototypes                    */
       9             : #include "prot_fx_enc.h" /* Function prototypes                    */
      10             : 
      11             : 
      12             : /*-------------------------------------------------------------------*
      13             :  * correlation_shift_fx
      14             :  *
      15             :  * Find normalized correlation correction dependent on estimated noise
      16             :  * Note: this variable is basically active only if noise suppression
      17             :  * is desactivated. Otherwise, for default NS = 14 dB and up to 10dB SNR
      18             :  * it can be assumed about 0
      19             :  *-------------------------------------------------------------------*/
      20             : 
      21     1196036 : Word16 correlation_shift_fx(                            /* o  : noise dependent voicing correction     Q15 */
      22             :                              const Word16 totalNoise_fx /* i/o: noise estimate over all critical bands  Q8 */
      23             : )
      24             : {
      25             :     Word16 corr_shift_fx, e_Noise, f_Noise, wtmp;
      26             :     Word32 Ltmp;
      27             : 
      28     1196036 :     corr_shift_fx = 0;
      29     1196036 :     move16();
      30             : 
      31     1196036 :     IF( GT_16( totalNoise_fx, 7215 ) ) /* to make corr_shift > 0.0 */
      32             :     {
      33             :         /*------------------------------------------------------------*
      34             :          * useful values range from 0 to 1 (can saturate at 1.0) Q31 value
      35             :          * corr_shift = 2.4492E-4 * exp(0.1596 * totalNoise) - 0.022
      36             :          * Result in Q14
      37             :          *------------------------------------------------------------*/
      38      114520 :         Ltmp = L_mult( totalNoise_fx, 7545 ); /* Q24 */
      39      114520 :         Ltmp = L_shr( Ltmp, 8 );              /* Q24 -> Q16 */
      40      114520 :         f_Noise = L_Extract_lc( Ltmp, &e_Noise );
      41      114520 :         wtmp = extract_l( Pow2( 14, f_Noise ) ); /* Put 14 as exponent */
      42             : 
      43      114520 :         e_Noise = sub( e_Noise, 14 );                        /* Retreive exponent of wtmp */
      44      114520 :         Ltmp = Mpy_32_16( 8, 837, wtmp );                    /* 2.4492e-4(Q31) * exp(0.1596*totalNoise) */
      45      114520 :         Ltmp = L_shl_sat( Ltmp, add( e_Noise, 15 ) );        /* Result in Q31 */
      46      114520 :         corr_shift_fx = round_fx( L_sub( Ltmp, 47244640 ) ); /* Represents corr_shift in Q15 */
      47             :     }
      48     1196036 :     corr_shift_fx = s_min( corr_shift_fx, 16384 ); /* limit to 0.5 */
      49             : 
      50     1196036 :     return corr_shift_fx;
      51             : }