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1 /***********************************************************************
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2 Copyright (c) 2006-2011, Skype Limited. All rights reserved.
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3 Redistribution and use in source and binary forms, with or without
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4 modification, are permitted provided that the following conditions
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5 are met:
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6 - Redistributions of source code must retain the above copyright notice,
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7 this list of conditions and the following disclaimer.
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8 - Redistributions in binary form must reproduce the above copyright
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9 notice, this list of conditions and the following disclaimer in the
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10 documentation and/or other materials provided with the distribution.
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11 - Neither the name of Internet Society, IETF or IETF Trust, nor the
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12 names of specific contributors, may be used to endorse or promote
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13 products derived from this software without specific prior written
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14 permission.
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15 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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16 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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17 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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18 ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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19 LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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20 CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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21 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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22 INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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23 CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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24 ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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25 POSSIBILITY OF SUCH DAMAGE.
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26 ***********************************************************************/
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27
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28 #ifdef HAVE_CONFIG_H
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29 #include "config.h"
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30 #endif
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31
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32 #include "main.h"
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33
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34 /* Find least-squares prediction gain for one signal based on another and quantize it */
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35 opus_int32 silk_stereo_find_predictor( /* O Returns predictor in Q13 */
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36 opus_int32 *ratio_Q14, /* O Ratio of residual and mid energies */
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37 const opus_int16 x[], /* I Basis signal */
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38 const opus_int16 y[], /* I Target signal */
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39 opus_int32 mid_res_amp_Q0[], /* I/O Smoothed mid, residual norms */
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40 opus_int length, /* I Number of samples */
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41 opus_int smooth_coef_Q16 /* I Smoothing coefficient */
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42 )
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43 {
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44 opus_int scale, scale1, scale2;
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45 opus_int32 nrgx, nrgy, corr, pred_Q13, pred2_Q10;
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46
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47 /* Find predictor */
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48 silk_sum_sqr_shift( &nrgx, &scale1, x, length );
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49 silk_sum_sqr_shift( &nrgy, &scale2, y, length );
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50 scale = silk_max_int( scale1, scale2 );
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51 scale = scale + ( scale & 1 ); /* make even */
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52 nrgy = silk_RSHIFT32( nrgy, scale - scale2 );
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53 nrgx = silk_RSHIFT32( nrgx, scale - scale1 );
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54 nrgx = silk_max_int( nrgx, 1 );
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55 corr = silk_inner_prod_aligned_scale( x, y, scale, length );
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56 pred_Q13 = silk_DIV32_varQ( corr, nrgx, 13 );
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57 pred_Q13 = silk_LIMIT( pred_Q13, -(1 << 14), 1 << 14 );
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58 pred2_Q10 = silk_SMULWB( pred_Q13, pred_Q13 );
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59
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60 /* Faster update for signals with large prediction parameters */
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61 smooth_coef_Q16 = (opus_int)silk_max_int( smooth_coef_Q16, silk_abs( pred2_Q10 ) );
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62
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63 /* Smoothed mid and residual norms */
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64 silk_assert( smooth_coef_Q16 < 32768 );
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65 scale = silk_RSHIFT( scale, 1 );
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66 mid_res_amp_Q0[ 0 ] = silk_SMLAWB( mid_res_amp_Q0[ 0 ], silk_LSHIFT( silk_SQRT_APPROX( nrgx ), scale ) - mid_res_amp_Q0[ 0 ],
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67 smooth_coef_Q16 );
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68 /* Residual energy = nrgy - 2 * pred * corr + pred^2 * nrgx */
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69 nrgy = silk_SUB_LSHIFT32( nrgy, silk_SMULWB( corr, pred_Q13 ), 3 + 1 );
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70 nrgy = silk_ADD_LSHIFT32( nrgy, silk_SMULWB( nrgx, pred2_Q10 ), 6 );
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71 mid_res_amp_Q0[ 1 ] = silk_SMLAWB( mid_res_amp_Q0[ 1 ], silk_LSHIFT( silk_SQRT_APPROX( nrgy ), scale ) - mid_res_amp_Q0[ 1 ],
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72 smooth_coef_Q16 );
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73
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74 /* Ratio of smoothed residual and mid norms */
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75 *ratio_Q14 = silk_DIV32_varQ( mid_res_amp_Q0[ 1 ], silk_max( mid_res_amp_Q0[ 0 ], 1 ), 14 );
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76 *ratio_Q14 = silk_LIMIT( *ratio_Q14, 0, 32767 );
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77
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78 return pred_Q13;
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79 }
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