ref: 9d48deb89985d6e88895fe6596850f9287da35b8
dir: /silk/silk_stereo_find_predictor.c/
/*********************************************************************** Copyright (c) 2006-2011, Skype Limited. All rights reserved. Redistribution and use in source and binary forms, with or without modification, (subject to the limitations in the disclaimer below) are permitted provided that the following conditions are met: - Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. - Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. - Neither the name of Skype Limited, nor the names of specific contributors, may be used to endorse or promote products derived from this software without specific prior written permission. NO EXPRESS OR IMPLIED LICENSES TO ANY PARTY'S PATENT RIGHTS ARE GRANTED BY THIS LICENSE. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ''AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. ***********************************************************************/ #ifdef HAVE_CONFIG_H #include "config.h" #endif #include "silk_main.h" /* Find least-squares prediction gain for one signal based on another and quantize it */ opus_int32 silk_stereo_find_predictor( /* O Returns predictor in Q13 */ opus_int32 *ratio_Q14, /* O Ratio of residual and mid energies */ const opus_int16 x[], /* I Basis signal */ const opus_int16 y[], /* I Target signal */ opus_int32 mid_res_amp_Q0[], /* I/O Smoothed mid, residual norms */ opus_int length, /* I Number of samples */ opus_int smooth_coef_Q16 /* I Smoothing coefficient */ ) { opus_int scale, scale1, scale2; opus_int32 nrgx, nrgy, corr, pred_Q13; /* Find predictor */ silk_sum_sqr_shift( &nrgx, &scale1, x, length ); silk_sum_sqr_shift( &nrgy, &scale2, y, length ); scale = SKP_max( scale1, scale2 ); scale = scale + ( scale & 1 ); /* make even */ nrgy = SKP_RSHIFT32( nrgy, scale - scale2 ); nrgx = SKP_RSHIFT32( nrgx, scale - scale1 ); nrgx = SKP_max( nrgx, 1 ); corr = silk_inner_prod_aligned_scale( x, y, scale, length ); pred_Q13 = silk_DIV32_varQ( corr, nrgx, 13 ); pred_Q13 = SKP_SAT16( pred_Q13 ); /* Smoothed mid and residual norms */ SKP_assert( smooth_coef_Q16 < 32768 ); scale = SKP_RSHIFT( scale, 1 ); mid_res_amp_Q0[ 0 ] = SKP_SMLAWB( mid_res_amp_Q0[ 0 ], SKP_LSHIFT( silk_SQRT_APPROX( nrgx ), scale ) - mid_res_amp_Q0[ 0 ], smooth_coef_Q16 ); nrgy = SKP_SUB_LSHIFT32( nrgy, SKP_SMULWB( corr, pred_Q13 ), 3 ); mid_res_amp_Q0[ 1 ] = SKP_SMLAWB( mid_res_amp_Q0[ 1 ], SKP_LSHIFT( silk_SQRT_APPROX( nrgy ), scale ) - mid_res_amp_Q0[ 1 ], smooth_coef_Q16 ); /* Ratio of smoothed residual and mid norms */ *ratio_Q14 = silk_DIV32_varQ( mid_res_amp_Q0[ 1 ], SKP_max( mid_res_amp_Q0[ 0 ], 1 ), 14 ); *ratio_Q14 = SKP_LIMIT( *ratio_Q14, 0, 32767 ); return pred_Q13; }