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