ref: c77b96333b471c7b8a89852ee941e6a8987751b4
dir: /silk/SKP_Silk_stereo_find_predictor.c/
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#include "SKP_Silk_main.h"
/* Find least-squares prediction gain for one signal based on another and quantize it */
SKP_int32 SKP_Silk_stereo_find_predictor( /* O Returns predictor in Q13 */
const SKP_int16 x[], /* I Basis signal */
const SKP_int16 y[], /* I Target signal */
SKP_int length /* I Number of samples */
)
{
SKP_int scale, scale1, scale2;
SKP_int32 nrg1, nrg2, corr, pred_Q13;
/* Find predictor */
SKP_Silk_sum_sqr_shift( &nrg1, &scale1, x, length );
SKP_Silk_sum_sqr_shift( &nrg2, &scale2, y, length );
if( scale1 > scale2 ) {
scale = scale1;
} else {
scale = scale2;
nrg1 = SKP_RSHIFT32( nrg1, scale2 - scale1 );
}
corr = SKP_Silk_inner_prod_aligned_scale( x, y, scale, length );
pred_Q13 = SKP_DIV32_varQ( corr, SKP_max( nrg1, 1 ), 13 );
pred_Q13 = SKP_LIMIT( pred_Q13, -SKP_FIX_CONST( 10, 13 ), SKP_FIX_CONST( 10, 13 ) );
return pred_Q13;
}