73 lines
3.3 KiB
C
73 lines
3.3 KiB
C
/***********************************************************************
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Copyright (c) 2006-2011, Skype Limited. All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions
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are met:
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- Redistributions of source code must retain the above copyright notice,
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this list of conditions and the following disclaimer.
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- Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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- Neither the name of Internet Society, IETF or IETF Trust, nor the
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names of specific contributors, may be used to endorse or promote
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products derived from this software without specific prior written
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permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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POSSIBILITY OF SUCH DAMAGE.
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***********************************************************************/
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include "main.h"
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/* Quantize mid/side predictors */
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void silk_stereo_quant_pred(
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opus_int32 pred_Q13[], /* I/O Predictors (out: quantized) */
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opus_int8 ix[ 2 ][ 3 ] /* O Quantization indices */
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)
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{
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opus_int i, j, n;
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opus_int32 low_Q13, step_Q13, lvl_Q13, err_min_Q13, err_Q13, quant_pred_Q13 = 0;
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/* Quantize */
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for( n = 0; n < 2; n++ ) {
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/* Brute-force search over quantization levels */
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err_min_Q13 = silk_int32_MAX;
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for( i = 0; i < STEREO_QUANT_TAB_SIZE - 1; i++ ) {
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low_Q13 = silk_stereo_pred_quant_Q13[ i ];
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step_Q13 = silk_SMULWB( silk_stereo_pred_quant_Q13[ i + 1 ] - low_Q13,
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SILK_FIX_CONST( 0.5 / STEREO_QUANT_SUB_STEPS, 16 ) );
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for( j = 0; j < STEREO_QUANT_SUB_STEPS; j++ ) {
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lvl_Q13 = silk_SMLABB( low_Q13, step_Q13, 2 * j + 1 );
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err_Q13 = silk_abs( pred_Q13[ n ] - lvl_Q13 );
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if( err_Q13 < err_min_Q13 ) {
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err_min_Q13 = err_Q13;
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quant_pred_Q13 = lvl_Q13;
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ix[ n ][ 0 ] = i;
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ix[ n ][ 1 ] = j;
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} else {
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/* Error increasing, so we're past the optimum */
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goto done;
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}
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}
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}
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done:
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ix[ n ][ 2 ] = silk_DIV32_16( ix[ n ][ 0 ], 3 );
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ix[ n ][ 0 ] -= ix[ n ][ 2 ] * 3;
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pred_Q13[ n ] = quant_pred_Q13;
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}
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/* Subtract second from first predictor (helps when actually applying these) */
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pred_Q13[ 0 ] -= pred_Q13[ 1 ];
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}
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