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- #ifdef HAVE_CONFIG_H
- #include "config.h"
- #endif
- #include "main.h"
- opus_int32 silk_stereo_find_predictor(
- opus_int32 *ratio_Q14,
- const opus_int16 x[],
- const opus_int16 y[],
- opus_int32 mid_res_amp_Q0[],
- opus_int length,
- opus_int smooth_coef_Q16
- )
- {
- opus_int scale, scale1, scale2;
- opus_int32 nrgx, nrgy, corr, pred_Q13, pred2_Q10;
-
- silk_sum_sqr_shift( &nrgx, &scale1, x, length );
- silk_sum_sqr_shift( &nrgy, &scale2, y, length );
- scale = silk_max_int( scale1, scale2 );
- scale = scale + ( scale & 1 );
- nrgy = silk_RSHIFT32( nrgy, scale - scale2 );
- nrgx = silk_RSHIFT32( nrgx, scale - scale1 );
- nrgx = silk_max_int( nrgx, 1 );
- corr = silk_inner_prod_aligned_scale( x, y, scale, length );
- pred_Q13 = silk_DIV32_varQ( corr, nrgx, 13 );
- pred_Q13 = silk_LIMIT( pred_Q13, -(1 << 14), 1 << 14 );
- pred2_Q10 = silk_SMULWB( pred_Q13, pred_Q13 );
-
- smooth_coef_Q16 = (opus_int)silk_max_int( smooth_coef_Q16, silk_abs( pred2_Q10 ) );
-
- silk_assert( smooth_coef_Q16 < 32768 );
- scale = silk_RSHIFT( scale, 1 );
- mid_res_amp_Q0[ 0 ] = silk_SMLAWB( mid_res_amp_Q0[ 0 ], silk_LSHIFT( silk_SQRT_APPROX( nrgx ), scale ) - mid_res_amp_Q0[ 0 ],
- smooth_coef_Q16 );
-
- nrgy = silk_SUB_LSHIFT32( nrgy, silk_SMULWB( corr, pred_Q13 ), 3 + 1 );
- nrgy = silk_ADD_LSHIFT32( nrgy, silk_SMULWB( nrgx, pred2_Q10 ), 6 );
- mid_res_amp_Q0[ 1 ] = silk_SMLAWB( mid_res_amp_Q0[ 1 ], silk_LSHIFT( silk_SQRT_APPROX( nrgy ), scale ) - mid_res_amp_Q0[ 1 ],
- smooth_coef_Q16 );
-
- *ratio_Q14 = silk_DIV32_varQ( mid_res_amp_Q0[ 1 ], silk_max( mid_res_amp_Q0[ 0 ], 1 ), 14 );
- *ratio_Q14 = silk_LIMIT( *ratio_Q14, 0, 32767 );
- return pred_Q13;
- }
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