Commit a4acf15b authored by Dominik Weckbecker's avatar Dominik Weckbecker 💬
Browse files

remove trivial conversion AMBIX<->SN3D

parent 5859f1f4

lib_util/ambi_convert.c

+0 −33
Original line number Diff line number Diff line
@@ -96,23 +96,6 @@ static const float FM_SN3D[AMBI_MAX_CHANNELS] = { SQRT_2_, 
                                                  INV_TWO_OVER_SQRT_3_, INV_TWO_OVER_SQRT_3_, 1.0f, INV_TWO_OVER_SQRT_3_, INV_TWO_OVER_SQRT_3_,

                                                  INV_SQRT_8_OVER_5_, INV_SQRT_3_OVER_5_, INV_SQRT_45_OVER_32_, 1.0f, INV_SQRT_45_OVER_32_, INV_SQRT_3_OVER_5_, INV_SQRT_8_OVER_5_ };



/*

   Curiously, not everyone seems to have the same understanding of what SN3D means. The Ambix paper

   (Nachbar et al. : AMBIX - A SUGGESTED AMBISONICS FORMAT) has an additional 1/sqrt(4*pi) in the

   normalization factor (see Eq. (3)) as compared to the tables in IVAS.

*/



static const float AMBIX_SN3D[AMBI_MAX_CHANNELS] = { INV_SQRT_FOUR_PI_,

                                                     INV_SQRT_FOUR_PI_, INV_SQRT_FOUR_PI_, INV_SQRT_FOUR_PI_,

                                                     INV_SQRT_FOUR_PI_, INV_SQRT_FOUR_PI_, INV_SQRT_FOUR_PI_, INV_SQRT_FOUR_PI_, INV_SQRT_FOUR_PI_,

                                                     INV_SQRT_FOUR_PI_, INV_SQRT_FOUR_PI_, INV_SQRT_FOUR_PI_, INV_SQRT_FOUR_PI_, INV_SQRT_FOUR_PI_, INV_SQRT_FOUR_PI_, INV_SQRT_FOUR_PI_ };



static const float SN3D_AMBIX[AMBI_MAX_CHANNELS] = { SQRT_FOUR_PI_,

                                                     SQRT_FOUR_PI_, SQRT_FOUR_PI_, SQRT_FOUR_PI_,

                                                     SQRT_FOUR_PI_, SQRT_FOUR_PI_, SQRT_FOUR_PI_, SQRT_FOUR_PI_, SQRT_FOUR_PI_,

                                                     SQRT_FOUR_PI_, SQRT_FOUR_PI_, SQRT_FOUR_PI_, SQRT_FOUR_PI_, SQRT_FOUR_PI_, SQRT_FOUR_PI_, SQRT_FOUR_PI_ };





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

    channel re-ordering tables

   ---------------------------- */
@@ -156,10 +139,6 @@ int16_t convert_ambi_format( float *in[], float *out[], int16_t order, AMBI_FMT 
            renormalize_channels( in, out, order, AMBI_NORM_SN3D, AMBI_NORM_MAXN );

            reorder_channels( in, out, order, AMBI_CHANNEL_ORDER_ACN, AMBI_CHANNEL_ORDER_FM );

        }

        else if ( out_format == AMBI_FMT_AMBIX )

        {

            renormalize_channels( in, out, order, AMBI_NORM_SN3D, AMBI_NORM_AMBIX );

        }

        else if ( out_format == AMBI_FMT_SID_SN3D )

        {

            reorder_channels( in, out, order, AMBI_CHANNEL_ORDER_ACN, AMBI_CHANNEL_ORDER_SID );
@@ -185,10 +164,6 @@ int16_t convert_ambi_format( float *in[], float *out[], int16_t order, AMBI_FMT 
            reorder_channels( in, out, order, AMBI_CHANNEL_ORDER_FM, AMBI_CHANNEL_ORDER_ACN );

            renormalize_channels( in, out, order, AMBI_NORM_MAXN, AMBI_NORM_SN3D );

        }

        else if ( in_format == AMBI_FMT_AMBIX )

        {

            renormalize_channels( in, out, order, AMBI_NORM_AMBIX, AMBI_NORM_SN3D );

        }

        else if ( in_format == AMBI_FMT_SID_SN3D )

        {

            reorder_channels( in, out, order, AMBI_CHANNEL_ORDER_SID, AMBI_CHANNEL_ORDER_ACN );
@@ -229,10 +204,6 @@ int16_t renormalize_channels( float *in[], float *out[], int16_t order, AMBI_CHA 
        {

            conversion_table = SN3D_MAXN;

        }

        else if ( out_format == AMBI_NORM_AMBIX )

        {

            conversion_table = SN3D_AMBIX;

        }

        else if ( out_format == AMBI_NORM_FM )

        {

            conversion_table = SN3D_FM;
@@ -252,10 +223,6 @@ int16_t renormalize_channels( float *in[], float *out[], int16_t order, AMBI_CHA 
        {

            conversion_table = MAXN_SN3D;

        }

        if ( in_format == AMBI_NORM_AMBIX )

        {

            conversion_table = AMBIX_SN3D;

        }

        else if ( in_format == AMBI_NORM_FM )

        {

            conversion_table = FM_SN3D;

lib_util/ambi_convert.h

+0 −1
Original line number Diff line number Diff line
@@ -49,7 +49,6 @@ typedef enum 
{

    AMBI_NORM_SN3D = 0,

    AMBI_NORM_N3D,

    AMBI_NORM_AMBIX,

    AMBI_NORM_MAXN,

    AMBI_NORM_FM

} AMBI_CHANNEL_NORM;