| /*********************************************************************** |
| 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: |
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| 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 |
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| ***********************************************************************/ |
| |
| #ifdef HAVE_CONFIG_H |
| #include "config.h" |
| #endif |
| |
| #include "main.h" |
| |
| /* Quantize mid/side predictors */ |
| void silk_stereo_quant_pred( |
| opus_int32 pred_Q13[], /* I/O Predictors (out: quantized) */ |
| opus_int8 ix[ 2 ][ 3 ] /* O Quantization indices */ |
| ) |
| { |
| opus_int i, j, n; |
| opus_int32 low_Q13, step_Q13, lvl_Q13, err_min_Q13, err_Q13, quant_pred_Q13 = 0; |
| |
| /* Quantize */ |
| for( n = 0; n < 2; n++ ) { |
| /* Brute-force search over quantization levels */ |
| err_min_Q13 = silk_int32_MAX; |
| for( i = 0; i < STEREO_QUANT_TAB_SIZE - 1; i++ ) { |
| low_Q13 = silk_stereo_pred_quant_Q13[ i ]; |
| step_Q13 = silk_SMULWB( silk_stereo_pred_quant_Q13[ i + 1 ] - low_Q13, |
| SILK_FIX_CONST( 0.5 / STEREO_QUANT_SUB_STEPS, 16 ) ); |
| for( j = 0; j < STEREO_QUANT_SUB_STEPS; j++ ) { |
| lvl_Q13 = silk_SMLABB( low_Q13, step_Q13, 2 * j + 1 ); |
| err_Q13 = silk_abs( pred_Q13[ n ] - lvl_Q13 ); |
| if( err_Q13 < err_min_Q13 ) { |
| err_min_Q13 = err_Q13; |
| quant_pred_Q13 = lvl_Q13; |
| ix[ n ][ 0 ] = i; |
| ix[ n ][ 1 ] = j; |
| } else { |
| /* Error increasing, so we're past the optimum */ |
| goto done; |
| } |
| } |
| } |
| done: |
| ix[ n ][ 2 ] = silk_DIV32_16( ix[ n ][ 0 ], 3 ); |
| ix[ n ][ 0 ] -= ix[ n ][ 2 ] * 3; |
| pred_Q13[ n ] = quant_pred_Q13; |
| } |
| |
| /* Subtract second from first predictor (helps when actually applying these) */ |
| pred_Q13[ 0 ] -= pred_Q13[ 1 ]; |
| } |