1*a58d3d2aSXin Li /***********************************************************************
2*a58d3d2aSXin Li Copyright (c) 2006-2011, Skype Limited. All rights reserved.
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5*a58d3d2aSXin Li are met:
6*a58d3d2aSXin Li - Redistributions of source code must retain the above copyright notice,
7*a58d3d2aSXin Li this list of conditions and the following disclaimer.
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13*a58d3d2aSXin Li products derived from this software without specific prior written
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15*a58d3d2aSXin Li THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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26*a58d3d2aSXin Li ***********************************************************************/
27*a58d3d2aSXin Li
28*a58d3d2aSXin Li #ifdef HAVE_CONFIG_H
29*a58d3d2aSXin Li #include "config.h"
30*a58d3d2aSXin Li #endif
31*a58d3d2aSXin Li
32*a58d3d2aSXin Li #include "main.h"
33*a58d3d2aSXin Li
34*a58d3d2aSXin Li /* Convert adaptive Mid/Side representation to Left/Right stereo signal */
silk_stereo_MS_to_LR(stereo_dec_state * state,opus_int16 x1[],opus_int16 x2[],const opus_int32 pred_Q13[],opus_int fs_kHz,opus_int frame_length)35*a58d3d2aSXin Li void silk_stereo_MS_to_LR(
36*a58d3d2aSXin Li stereo_dec_state *state, /* I/O State */
37*a58d3d2aSXin Li opus_int16 x1[], /* I/O Left input signal, becomes mid signal */
38*a58d3d2aSXin Li opus_int16 x2[], /* I/O Right input signal, becomes side signal */
39*a58d3d2aSXin Li const opus_int32 pred_Q13[], /* I Predictors */
40*a58d3d2aSXin Li opus_int fs_kHz, /* I Samples rate (kHz) */
41*a58d3d2aSXin Li opus_int frame_length /* I Number of samples */
42*a58d3d2aSXin Li )
43*a58d3d2aSXin Li {
44*a58d3d2aSXin Li opus_int n, denom_Q16, delta0_Q13, delta1_Q13;
45*a58d3d2aSXin Li opus_int32 sum, diff, pred0_Q13, pred1_Q13;
46*a58d3d2aSXin Li
47*a58d3d2aSXin Li /* Buffering */
48*a58d3d2aSXin Li silk_memcpy( x1, state->sMid, 2 * sizeof( opus_int16 ) );
49*a58d3d2aSXin Li silk_memcpy( x2, state->sSide, 2 * sizeof( opus_int16 ) );
50*a58d3d2aSXin Li silk_memcpy( state->sMid, &x1[ frame_length ], 2 * sizeof( opus_int16 ) );
51*a58d3d2aSXin Li silk_memcpy( state->sSide, &x2[ frame_length ], 2 * sizeof( opus_int16 ) );
52*a58d3d2aSXin Li
53*a58d3d2aSXin Li /* Interpolate predictors and add prediction to side channel */
54*a58d3d2aSXin Li pred0_Q13 = state->pred_prev_Q13[ 0 ];
55*a58d3d2aSXin Li pred1_Q13 = state->pred_prev_Q13[ 1 ];
56*a58d3d2aSXin Li denom_Q16 = silk_DIV32_16( (opus_int32)1 << 16, STEREO_INTERP_LEN_MS * fs_kHz );
57*a58d3d2aSXin Li delta0_Q13 = silk_RSHIFT_ROUND( silk_SMULBB( pred_Q13[ 0 ] - state->pred_prev_Q13[ 0 ], denom_Q16 ), 16 );
58*a58d3d2aSXin Li delta1_Q13 = silk_RSHIFT_ROUND( silk_SMULBB( pred_Q13[ 1 ] - state->pred_prev_Q13[ 1 ], denom_Q16 ), 16 );
59*a58d3d2aSXin Li for( n = 0; n < STEREO_INTERP_LEN_MS * fs_kHz; n++ ) {
60*a58d3d2aSXin Li pred0_Q13 += delta0_Q13;
61*a58d3d2aSXin Li pred1_Q13 += delta1_Q13;
62*a58d3d2aSXin Li sum = silk_LSHIFT( silk_ADD_LSHIFT32( x1[ n ] + (opus_int32)x1[ n + 2 ], x1[ n + 1 ], 1 ), 9 ); /* Q11 */
63*a58d3d2aSXin Li sum = silk_SMLAWB( silk_LSHIFT( (opus_int32)x2[ n + 1 ], 8 ), sum, pred0_Q13 ); /* Q8 */
64*a58d3d2aSXin Li sum = silk_SMLAWB( sum, silk_LSHIFT( (opus_int32)x1[ n + 1 ], 11 ), pred1_Q13 ); /* Q8 */
65*a58d3d2aSXin Li x2[ n + 1 ] = (opus_int16)silk_SAT16( silk_RSHIFT_ROUND( sum, 8 ) );
66*a58d3d2aSXin Li }
67*a58d3d2aSXin Li pred0_Q13 = pred_Q13[ 0 ];
68*a58d3d2aSXin Li pred1_Q13 = pred_Q13[ 1 ];
69*a58d3d2aSXin Li for( n = STEREO_INTERP_LEN_MS * fs_kHz; n < frame_length; n++ ) {
70*a58d3d2aSXin Li sum = silk_LSHIFT( silk_ADD_LSHIFT32( x1[ n ] + (opus_int32)x1[ n + 2 ], x1[ n + 1 ], 1 ), 9 ); /* Q11 */
71*a58d3d2aSXin Li sum = silk_SMLAWB( silk_LSHIFT( (opus_int32)x2[ n + 1 ], 8 ), sum, pred0_Q13 ); /* Q8 */
72*a58d3d2aSXin Li sum = silk_SMLAWB( sum, silk_LSHIFT( (opus_int32)x1[ n + 1 ], 11 ), pred1_Q13 ); /* Q8 */
73*a58d3d2aSXin Li x2[ n + 1 ] = (opus_int16)silk_SAT16( silk_RSHIFT_ROUND( sum, 8 ) );
74*a58d3d2aSXin Li }
75*a58d3d2aSXin Li state->pred_prev_Q13[ 0 ] = pred_Q13[ 0 ];
76*a58d3d2aSXin Li state->pred_prev_Q13[ 1 ] = pred_Q13[ 1 ];
77*a58d3d2aSXin Li
78*a58d3d2aSXin Li /* Convert to left/right signals */
79*a58d3d2aSXin Li for( n = 0; n < frame_length; n++ ) {
80*a58d3d2aSXin Li sum = x1[ n + 1 ] + (opus_int32)x2[ n + 1 ];
81*a58d3d2aSXin Li diff = x1[ n + 1 ] - (opus_int32)x2[ n + 1 ];
82*a58d3d2aSXin Li x1[ n + 1 ] = (opus_int16)silk_SAT16( sum );
83*a58d3d2aSXin Li x2[ n + 1 ] = (opus_int16)silk_SAT16( diff );
84*a58d3d2aSXin Li }
85*a58d3d2aSXin Li }
86