cannam@154: /***********************************************************************
cannam@154: Copyright (c) 2006-2011, Skype Limited. All rights reserved.
cannam@154: Redistribution and use in source and binary forms, with or without
cannam@154: modification, are permitted provided that the following conditions
cannam@154: are met:
cannam@154: - Redistributions of source code must retain the above copyright notice,
cannam@154: this list of conditions and the following disclaimer.
cannam@154: - Redistributions in binary form must reproduce the above copyright
cannam@154: notice, this list of conditions and the following disclaimer in the
cannam@154: documentation and/or other materials provided with the distribution.
cannam@154: - Neither the name of Internet Society, IETF or IETF Trust, nor the
cannam@154: names of specific contributors, may be used to endorse or promote
cannam@154: products derived from this software without specific prior written
cannam@154: permission.
cannam@154: THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
cannam@154: AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
cannam@154: IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
cannam@154: ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
cannam@154: LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
cannam@154: CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
cannam@154: SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
cannam@154: INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
cannam@154: CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
cannam@154: ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
cannam@154: POSSIBILITY OF SUCH DAMAGE.
cannam@154: ***********************************************************************/
cannam@154: 
cannam@154: #ifdef HAVE_CONFIG_H
cannam@154: #include "config.h"
cannam@154: #endif
cannam@154: 
cannam@154: #include "main.h"
cannam@154: 
cannam@154: /* Quantize mid/side predictors */
cannam@154: void silk_stereo_quant_pred(
cannam@154:     opus_int32                  pred_Q13[],                     /* I/O  Predictors (out: quantized)                 */
cannam@154:     opus_int8                   ix[ 2 ][ 3 ]                    /* O    Quantization indices                        */
cannam@154: )
cannam@154: {
cannam@154:     opus_int   i, j, n;
cannam@154:     opus_int32 low_Q13, step_Q13, lvl_Q13, err_min_Q13, err_Q13, quant_pred_Q13 = 0;
cannam@154: 
cannam@154:     /* Quantize */
cannam@154:     for( n = 0; n < 2; n++ ) {
cannam@154:         /* Brute-force search over quantization levels */
cannam@154:         err_min_Q13 = silk_int32_MAX;
cannam@154:         for( i = 0; i < STEREO_QUANT_TAB_SIZE - 1; i++ ) {
cannam@154:             low_Q13 = silk_stereo_pred_quant_Q13[ i ];
cannam@154:             step_Q13 = silk_SMULWB( silk_stereo_pred_quant_Q13[ i + 1 ] - low_Q13,
cannam@154:                 SILK_FIX_CONST( 0.5 / STEREO_QUANT_SUB_STEPS, 16 ) );
cannam@154:             for( j = 0; j < STEREO_QUANT_SUB_STEPS; j++ ) {
cannam@154:                 lvl_Q13 = silk_SMLABB( low_Q13, step_Q13, 2 * j + 1 );
cannam@154:                 err_Q13 = silk_abs( pred_Q13[ n ] - lvl_Q13 );
cannam@154:                 if( err_Q13 < err_min_Q13 ) {
cannam@154:                     err_min_Q13 = err_Q13;
cannam@154:                     quant_pred_Q13 = lvl_Q13;
cannam@154:                     ix[ n ][ 0 ] = i;
cannam@154:                     ix[ n ][ 1 ] = j;
cannam@154:                 } else {
cannam@154:                     /* Error increasing, so we're past the optimum */
cannam@154:                     goto done;
cannam@154:                 }
cannam@154:             }
cannam@154:         }
cannam@154:         done:
cannam@154:         ix[ n ][ 2 ]  = silk_DIV32_16( ix[ n ][ 0 ], 3 );
cannam@154:         ix[ n ][ 0 ] -= ix[ n ][ 2 ] * 3;
cannam@154:         pred_Q13[ n ] = quant_pred_Q13;
cannam@154:     }
cannam@154: 
cannam@154:     /* Subtract second from first predictor (helps when actually applying these) */
cannam@154:     pred_Q13[ 0 ] -= pred_Q13[ 1 ];
cannam@154: }