Commit da9755c9 authored by vaillancour's avatar vaillancour
Browse files

comment function stereo_smooth_LR_transition()

parent bec84e72

lib_enc/ivas_stereo_td_analysis.c

+40 −5
Original line number Diff line number Diff line
@@ -629,7 +629,7 @@ static int16_t Get_dt_lt_ener( 
    }



    /*----------------------------------------------------------------*

     * Compute the 1st order energy difference difference

     * Compute the 1st order energy difference 

     *----------------------------------------------------------------*/



    *ener_R_dt = *tdm_lt_rms_R - *tdm_last_ener_lt_R;
@@ -1362,7 +1362,9 @@ static void Get_corr_n( 
    ener_side = 1e-6f;



    /*----------------------------------------------------------------*

     * Find the normalized correlation between: left/mono and right/mono based

     * Find the normalized correlation between: left/mono and right/mono 

     * Find the energy difference between side and mono, this info is later 

     * used to help determine the out of phase signal

     *----------------------------------------------------------------*/



    if ( tdm_SM_calc_flag )
@@ -1406,9 +1408,9 @@ static void Get_corr_n( 


/*! r: smoothed position */

static int16_t stereo_smooth_LR_transition(

    int16_t *tdm_prev_stable_idx,           /* i/o: Previous Transmitted ratio index                */

    int16_t *tdm_prev_stable_idx,           /* i/o: Last energy ratio index considered stable       */

    int16_t *tdm_ratio_transition_mov_flag, /* i/o: Flag that indicates that L-R energy is changing */

    int16_t tdm_last_ratio_idx,             /* i  : last TDM ratio index                            */

    int16_t tdm_last_ratio_idx,             /* i  : last transmitted TDM ratio index                */

    int16_t *tdm_prev_desired_idx,          /* i/o: Previous Transmitted ratio index                */

    int16_t *tdm_ratio_transition_cnt,      /* i/o: Counter                                         */

    const int16_t tdm_SM_flag,              /* i  : channel combination scheme flag for current frame */
@@ -1417,15 +1419,48 @@ static int16_t stereo_smooth_LR_transition( 
{

    int16_t idx;



    /*-------------------------------------------------------------------*

     * if the signal is considered as out of phase, 

     * energy ratio desired index is forced to mid-range (15)

     *-------------------------------------------------------------------*/

    if ( tdm_SM_flag == 1 )

    {

        desired_idx = 15;

    }



    /*-------------------------------------------------------------------*

     * if the energy ratio desired index is different than the previous 

     * stable energy index, it indicates that the energy is moving from 

     * its last stable position

     *-------------------------------------------------------------------*/

    if ( desired_idx != *tdm_prev_stable_idx )

    {

        *tdm_ratio_transition_mov_flag = 1;

    }

    /*-------------------------------------------------------------------*

     * When the moving energy flag is set to 1, 

     *   if the current energy ratio index is different from the previous 

     *   one

     *    then, 

     *      update the previous stable energy index with the last transmitted one 

     *      reset transition energy counter

     *   increment the transition energy counter by 4 

     *   

     * if the current energy ratio index + 2 is smaller than the last stable 

     * energy index

     *   then,

     *      the quantized energy index will be equal to the last stable index 

     *      minus the transition counter

     * else if the current energy ratio index - 2 is larger than the last 

     * stable energy index

     *   then,

     *      the quantized energy index will be equal to the last stable index 

     *      plus the transition counter

     * else 

     *      the quantized energy index is equal to the current energy index

     * 

     * this allows for a smoother transition from one stable energy index to 

     * another one when the energy gap is relatively big

     *-------------------------------------------------------------------*/



    if ( *tdm_ratio_transition_mov_flag == 1 )

    {