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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 /* Quantize mid/side predictors */
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35 void silk_stereo_quant_pred(
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36 opus_int32 pred_Q13[], /* I/O Predictors (out: quantized) */
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37 opus_int8 ix[ 2 ][ 3 ] /* O Quantization indices */
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38 )
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39 {
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40 opus_int i, j, n;
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41 opus_int32 low_Q13, step_Q13, lvl_Q13, err_min_Q13, err_Q13, quant_pred_Q13 = 0;
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42
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43 /* Quantize */
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44 for( n = 0; n < 2; n++ ) {
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45 /* Brute-force search over quantization levels */
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46 err_min_Q13 = silk_int32_MAX;
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47 for( i = 0; i < STEREO_QUANT_TAB_SIZE - 1; i++ ) {
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48 low_Q13 = silk_stereo_pred_quant_Q13[ i ];
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49 step_Q13 = silk_SMULWB( silk_stereo_pred_quant_Q13[ i + 1 ] - low_Q13,
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50 SILK_FIX_CONST( 0.5 / STEREO_QUANT_SUB_STEPS, 16 ) );
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51 for( j = 0; j < STEREO_QUANT_SUB_STEPS; j++ ) {
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52 lvl_Q13 = silk_SMLABB( low_Q13, step_Q13, 2 * j + 1 );
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53 err_Q13 = silk_abs( pred_Q13[ n ] - lvl_Q13 );
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54 if( err_Q13 < err_min_Q13 ) {
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55 err_min_Q13 = err_Q13;
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56 quant_pred_Q13 = lvl_Q13;
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57 ix[ n ][ 0 ] = i;
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58 ix[ n ][ 1 ] = j;
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59 } else {
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60 /* Error increasing, so we're past the optimum */
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61 goto done;
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62 }
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63 }
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64 }
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65 done:
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66 ix[ n ][ 2 ] = silk_DIV32_16( ix[ n ][ 0 ], 3 );
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67 ix[ n ][ 0 ] -= ix[ n ][ 2 ] * 3;
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68 pred_Q13[ n ] = quant_pred_Q13;
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69 }
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70
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71 /* Subtract second from first predictor (helps when actually applying these) */
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72 pred_Q13[ 0 ] -= pred_Q13[ 1 ];
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73 }
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