michael@0: /***********************************************************************
michael@0: Copyright (c) 2006-2011, Skype Limited. All rights reserved.
michael@0: Redistribution and use in source and binary forms, with or without
michael@0: modification, are permitted provided that the following conditions
michael@0: are met:
michael@0: - Redistributions of source code must retain the above copyright notice,
michael@0: this list of conditions and the following disclaimer.
michael@0: - Redistributions in binary form must reproduce the above copyright
michael@0: notice, this list of conditions and the following disclaimer in the
michael@0: documentation and/or other materials provided with the distribution.
michael@0: - Neither the name of Internet Society, IETF or IETF Trust, nor the
michael@0: names of specific contributors, may be used to endorse or promote
michael@0: products derived from this software without specific prior written
michael@0: permission.
michael@0: THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
michael@0: AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
michael@0: IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
michael@0: ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
michael@0: LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
michael@0: CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
michael@0: SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
michael@0: INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
michael@0: CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
michael@0: ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
michael@0: POSSIBILITY OF SUCH DAMAGE.
michael@0: ***********************************************************************/
michael@0: 
michael@0: #ifdef HAVE_CONFIG_H
michael@0: #include "config.h"
michael@0: #endif
michael@0: 
michael@0: #include "main.h"
michael@0: 
michael@0: /* Convert adaptive Mid/Side representation to Left/Right stereo signal */
michael@0: void silk_stereo_MS_to_LR(
michael@0:     stereo_dec_state            *state,                         /* I/O  State                                       */
michael@0:     opus_int16                  x1[],                           /* I/O  Left input signal, becomes mid signal       */
michael@0:     opus_int16                  x2[],                           /* I/O  Right input signal, becomes side signal     */
michael@0:     const opus_int32            pred_Q13[],                     /* I    Predictors                                  */
michael@0:     opus_int                    fs_kHz,                         /* I    Samples rate (kHz)                          */
michael@0:     opus_int                    frame_length                    /* I    Number of samples                           */
michael@0: )
michael@0: {
michael@0:     opus_int   n, denom_Q16, delta0_Q13, delta1_Q13;
michael@0:     opus_int32 sum, diff, pred0_Q13, pred1_Q13;
michael@0: 
michael@0:     /* Buffering */
michael@0:     silk_memcpy( x1, state->sMid,  2 * sizeof( opus_int16 ) );
michael@0:     silk_memcpy( x2, state->sSide, 2 * sizeof( opus_int16 ) );
michael@0:     silk_memcpy( state->sMid,  &x1[ frame_length ], 2 * sizeof( opus_int16 ) );
michael@0:     silk_memcpy( state->sSide, &x2[ frame_length ], 2 * sizeof( opus_int16 ) );
michael@0: 
michael@0:     /* Interpolate predictors and add prediction to side channel */
michael@0:     pred0_Q13  = state->pred_prev_Q13[ 0 ];
michael@0:     pred1_Q13  = state->pred_prev_Q13[ 1 ];
michael@0:     denom_Q16  = silk_DIV32_16( (opus_int32)1 << 16, STEREO_INTERP_LEN_MS * fs_kHz );
michael@0:     delta0_Q13 = silk_RSHIFT_ROUND( silk_SMULBB( pred_Q13[ 0 ] - state->pred_prev_Q13[ 0 ], denom_Q16 ), 16 );
michael@0:     delta1_Q13 = silk_RSHIFT_ROUND( silk_SMULBB( pred_Q13[ 1 ] - state->pred_prev_Q13[ 1 ], denom_Q16 ), 16 );
michael@0:     for( n = 0; n < STEREO_INTERP_LEN_MS * fs_kHz; n++ ) {
michael@0:         pred0_Q13 += delta0_Q13;
michael@0:         pred1_Q13 += delta1_Q13;
michael@0:         sum = silk_LSHIFT( silk_ADD_LSHIFT( x1[ n ] + x1[ n + 2 ], x1[ n + 1 ], 1 ), 9 );       /* Q11 */
michael@0:         sum = silk_SMLAWB( silk_LSHIFT( (opus_int32)x2[ n + 1 ], 8 ), sum, pred0_Q13 );         /* Q8  */
michael@0:         sum = silk_SMLAWB( sum, silk_LSHIFT( (opus_int32)x1[ n + 1 ], 11 ), pred1_Q13 );        /* Q8  */
michael@0:         x2[ n + 1 ] = (opus_int16)silk_SAT16( silk_RSHIFT_ROUND( sum, 8 ) );
michael@0:     }
michael@0:     pred0_Q13 = pred_Q13[ 0 ];
michael@0:     pred1_Q13 = pred_Q13[ 1 ];
michael@0:     for( n = STEREO_INTERP_LEN_MS * fs_kHz; n < frame_length; n++ ) {
michael@0:         sum = silk_LSHIFT( silk_ADD_LSHIFT( x1[ n ] + x1[ n + 2 ], x1[ n + 1 ], 1 ), 9 );       /* Q11 */
michael@0:         sum = silk_SMLAWB( silk_LSHIFT( (opus_int32)x2[ n + 1 ], 8 ), sum, pred0_Q13 );         /* Q8  */
michael@0:         sum = silk_SMLAWB( sum, silk_LSHIFT( (opus_int32)x1[ n + 1 ], 11 ), pred1_Q13 );        /* Q8  */
michael@0:         x2[ n + 1 ] = (opus_int16)silk_SAT16( silk_RSHIFT_ROUND( sum, 8 ) );
michael@0:     }
michael@0:     state->pred_prev_Q13[ 0 ] = pred_Q13[ 0 ];
michael@0:     state->pred_prev_Q13[ 1 ] = pred_Q13[ 1 ];
michael@0: 
michael@0:     /* Convert to left/right signals */
michael@0:     for( n = 0; n < frame_length; n++ ) {
michael@0:         sum  = x1[ n + 1 ] + (opus_int32)x2[ n + 1 ];
michael@0:         diff = x1[ n + 1 ] - (opus_int32)x2[ n + 1 ];
michael@0:         x1[ n + 1 ] = (opus_int16)silk_SAT16( sum );
michael@0:         x2[ n + 1 ] = (opus_int16)silk_SAT16( diff );
michael@0:     }
michael@0: }