1*a58d3d2aSXin Li /***********************************************************************
2*a58d3d2aSXin Li Copyright (c) 2006-2011, Skype Limited. All rights reserved.
3*a58d3d2aSXin Li Redistribution and use in source and binary forms, with or without
4*a58d3d2aSXin Li modification, are permitted provided that the following conditions
5*a58d3d2aSXin Li are met:
6*a58d3d2aSXin Li - Redistributions of source code must retain the above copyright notice,
7*a58d3d2aSXin Li this list of conditions and the following disclaimer.
8*a58d3d2aSXin Li - Redistributions in binary form must reproduce the above copyright
9*a58d3d2aSXin Li notice, this list of conditions and the following disclaimer in the
10*a58d3d2aSXin Li documentation and/or other materials provided with the distribution.
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13*a58d3d2aSXin Li products derived from this software without specific prior written
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15*a58d3d2aSXin Li THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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26*a58d3d2aSXin Li ***********************************************************************/
27*a58d3d2aSXin Li
28*a58d3d2aSXin Li #ifdef HAVE_CONFIG_H
29*a58d3d2aSXin Li #include "config.h"
30*a58d3d2aSXin Li #endif
31*a58d3d2aSXin Li
32*a58d3d2aSXin Li #include "main.h"
33*a58d3d2aSXin Li
34*a58d3d2aSXin Li /* Quantize mid/side predictors */
silk_stereo_quant_pred(opus_int32 pred_Q13[],opus_int8 ix[2][3])35*a58d3d2aSXin Li void silk_stereo_quant_pred(
36*a58d3d2aSXin Li opus_int32 pred_Q13[], /* I/O Predictors (out: quantized) */
37*a58d3d2aSXin Li opus_int8 ix[ 2 ][ 3 ] /* O Quantization indices */
38*a58d3d2aSXin Li )
39*a58d3d2aSXin Li {
40*a58d3d2aSXin Li opus_int i, j, n;
41*a58d3d2aSXin Li opus_int32 low_Q13, step_Q13, lvl_Q13, err_min_Q13, err_Q13, quant_pred_Q13 = 0;
42*a58d3d2aSXin Li
43*a58d3d2aSXin Li /* Quantize */
44*a58d3d2aSXin Li for( n = 0; n < 2; n++ ) {
45*a58d3d2aSXin Li /* Brute-force search over quantization levels */
46*a58d3d2aSXin Li err_min_Q13 = silk_int32_MAX;
47*a58d3d2aSXin Li for( i = 0; i < STEREO_QUANT_TAB_SIZE - 1; i++ ) {
48*a58d3d2aSXin Li low_Q13 = silk_stereo_pred_quant_Q13[ i ];
49*a58d3d2aSXin Li step_Q13 = silk_SMULWB( silk_stereo_pred_quant_Q13[ i + 1 ] - low_Q13,
50*a58d3d2aSXin Li SILK_FIX_CONST( 0.5 / STEREO_QUANT_SUB_STEPS, 16 ) );
51*a58d3d2aSXin Li for( j = 0; j < STEREO_QUANT_SUB_STEPS; j++ ) {
52*a58d3d2aSXin Li lvl_Q13 = silk_SMLABB( low_Q13, step_Q13, 2 * j + 1 );
53*a58d3d2aSXin Li err_Q13 = silk_abs( pred_Q13[ n ] - lvl_Q13 );
54*a58d3d2aSXin Li if( err_Q13 < err_min_Q13 ) {
55*a58d3d2aSXin Li err_min_Q13 = err_Q13;
56*a58d3d2aSXin Li quant_pred_Q13 = lvl_Q13;
57*a58d3d2aSXin Li ix[ n ][ 0 ] = i;
58*a58d3d2aSXin Li ix[ n ][ 1 ] = j;
59*a58d3d2aSXin Li } else {
60*a58d3d2aSXin Li /* Error increasing, so we're past the optimum */
61*a58d3d2aSXin Li goto done;
62*a58d3d2aSXin Li }
63*a58d3d2aSXin Li }
64*a58d3d2aSXin Li }
65*a58d3d2aSXin Li done:
66*a58d3d2aSXin Li ix[ n ][ 2 ] = silk_DIV32_16( ix[ n ][ 0 ], 3 );
67*a58d3d2aSXin Li ix[ n ][ 0 ] -= ix[ n ][ 2 ] * 3;
68*a58d3d2aSXin Li pred_Q13[ n ] = quant_pred_Q13;
69*a58d3d2aSXin Li }
70*a58d3d2aSXin Li
71*a58d3d2aSXin Li /* Subtract second from first predictor (helps when actually applying these) */
72*a58d3d2aSXin Li pred_Q13[ 0 ] -= pred_Q13[ 1 ];
73*a58d3d2aSXin Li }
74