Chris@69: /***********************************************************************
Chris@69: Copyright (c) 2006-2011, Skype Limited. All rights reserved.
Chris@69: Redistribution and use in source and binary forms, with or without
Chris@69: modification, are permitted provided that the following conditions
Chris@69: are met:
Chris@69: - Redistributions of source code must retain the above copyright notice,
Chris@69: this list of conditions and the following disclaimer.
Chris@69: - Redistributions in binary form must reproduce the above copyright
Chris@69: notice, this list of conditions and the following disclaimer in the
Chris@69: documentation and/or other materials provided with the distribution.
Chris@69: - Neither the name of Internet Society, IETF or IETF Trust, nor the
Chris@69: names of specific contributors, may be used to endorse or promote
Chris@69: products derived from this software without specific prior written
Chris@69: permission.
Chris@69: THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
Chris@69: AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
Chris@69: IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
Chris@69: ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
Chris@69: LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
Chris@69: CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
Chris@69: SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
Chris@69: INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
Chris@69: CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
Chris@69: ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
Chris@69: POSSIBILITY OF SUCH DAMAGE.
Chris@69: ***********************************************************************/
Chris@69: 
Chris@69: #ifdef HAVE_CONFIG_H
Chris@69: #include "config.h"
Chris@69: #endif
Chris@69: 
Chris@69: #include "main.h"
Chris@69: 
Chris@69: /* Convert adaptive Mid/Side representation to Left/Right stereo signal */
Chris@69: void silk_stereo_MS_to_LR(
Chris@69:     stereo_dec_state            *state,                         /* I/O  State                                       */
Chris@69:     opus_int16                  x1[],                           /* I/O  Left input signal, becomes mid signal       */
Chris@69:     opus_int16                  x2[],                           /* I/O  Right input signal, becomes side signal     */
Chris@69:     const opus_int32            pred_Q13[],                     /* I    Predictors                                  */
Chris@69:     opus_int                    fs_kHz,                         /* I    Samples rate (kHz)                          */
Chris@69:     opus_int                    frame_length                    /* I    Number of samples                           */
Chris@69: )
Chris@69: {
Chris@69:     opus_int   n, denom_Q16, delta0_Q13, delta1_Q13;
Chris@69:     opus_int32 sum, diff, pred0_Q13, pred1_Q13;
Chris@69: 
Chris@69:     /* Buffering */
Chris@69:     silk_memcpy( x1, state->sMid,  2 * sizeof( opus_int16 ) );
Chris@69:     silk_memcpy( x2, state->sSide, 2 * sizeof( opus_int16 ) );
Chris@69:     silk_memcpy( state->sMid,  &x1[ frame_length ], 2 * sizeof( opus_int16 ) );
Chris@69:     silk_memcpy( state->sSide, &x2[ frame_length ], 2 * sizeof( opus_int16 ) );
Chris@69: 
Chris@69:     /* Interpolate predictors and add prediction to side channel */
Chris@69:     pred0_Q13  = state->pred_prev_Q13[ 0 ];
Chris@69:     pred1_Q13  = state->pred_prev_Q13[ 1 ];
Chris@69:     denom_Q16  = silk_DIV32_16( (opus_int32)1 << 16, STEREO_INTERP_LEN_MS * fs_kHz );
Chris@69:     delta0_Q13 = silk_RSHIFT_ROUND( silk_SMULBB( pred_Q13[ 0 ] - state->pred_prev_Q13[ 0 ], denom_Q16 ), 16 );
Chris@69:     delta1_Q13 = silk_RSHIFT_ROUND( silk_SMULBB( pred_Q13[ 1 ] - state->pred_prev_Q13[ 1 ], denom_Q16 ), 16 );
Chris@69:     for( n = 0; n < STEREO_INTERP_LEN_MS * fs_kHz; n++ ) {
Chris@69:         pred0_Q13 += delta0_Q13;
Chris@69:         pred1_Q13 += delta1_Q13;
Chris@69:         sum = silk_LSHIFT( silk_ADD_LSHIFT( x1[ n ] + x1[ n + 2 ], x1[ n + 1 ], 1 ), 9 );       /* Q11 */
Chris@69:         sum = silk_SMLAWB( silk_LSHIFT( (opus_int32)x2[ n + 1 ], 8 ), sum, pred0_Q13 );         /* Q8  */
Chris@69:         sum = silk_SMLAWB( sum, silk_LSHIFT( (opus_int32)x1[ n + 1 ], 11 ), pred1_Q13 );        /* Q8  */
Chris@69:         x2[ n + 1 ] = (opus_int16)silk_SAT16( silk_RSHIFT_ROUND( sum, 8 ) );
Chris@69:     }
Chris@69:     pred0_Q13 = pred_Q13[ 0 ];
Chris@69:     pred1_Q13 = pred_Q13[ 1 ];
Chris@69:     for( n = STEREO_INTERP_LEN_MS * fs_kHz; n < frame_length; n++ ) {
Chris@69:         sum = silk_LSHIFT( silk_ADD_LSHIFT( x1[ n ] + x1[ n + 2 ], x1[ n + 1 ], 1 ), 9 );       /* Q11 */
Chris@69:         sum = silk_SMLAWB( silk_LSHIFT( (opus_int32)x2[ n + 1 ], 8 ), sum, pred0_Q13 );         /* Q8  */
Chris@69:         sum = silk_SMLAWB( sum, silk_LSHIFT( (opus_int32)x1[ n + 1 ], 11 ), pred1_Q13 );        /* Q8  */
Chris@69:         x2[ n + 1 ] = (opus_int16)silk_SAT16( silk_RSHIFT_ROUND( sum, 8 ) );
Chris@69:     }
Chris@69:     state->pred_prev_Q13[ 0 ] = pred_Q13[ 0 ];
Chris@69:     state->pred_prev_Q13[ 1 ] = pred_Q13[ 1 ];
Chris@69: 
Chris@69:     /* Convert to left/right signals */
Chris@69:     for( n = 0; n < frame_length; n++ ) {
Chris@69:         sum  = x1[ n + 1 ] + (opus_int32)x2[ n + 1 ];
Chris@69:         diff = x1[ n + 1 ] - (opus_int32)x2[ n + 1 ];
Chris@69:         x1[ n + 1 ] = (opus_int16)silk_SAT16( sum );
Chris@69:         x2[ n + 1 ] = (opus_int16)silk_SAT16( diff );
Chris@69:     }
Chris@69: }