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26 ***********************************************************************/
27
28 #ifdef HAVE_CONFIG_H
29 #include "config.h"
30 #endif
31
32 #include "main.h"
33
34 /* 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 void silk_stereo_MS_to_LR(
36 stereo_dec_state *state, /* I/O State */
37 opus_int16 x1[], /* I/O Left input signal, becomes mid signal */
38 opus_int16 x2[], /* I/O Right input signal, becomes side signal */
39 const opus_int32 pred_Q13[], /* I Predictors */
40 opus_int fs_kHz, /* I Samples rate (kHz) */
41 opus_int frame_length /* I Number of samples */
42 )
43 {
44 opus_int n, denom_Q16, delta0_Q13, delta1_Q13;
45 opus_int32 sum, diff, pred0_Q13, pred1_Q13;
46
47 /* Buffering */
48 silk_memcpy( x1, state->sMid, 2 * sizeof( opus_int16 ) );
49 silk_memcpy( x2, state->sSide, 2 * sizeof( opus_int16 ) );
50 silk_memcpy( state->sMid, &x1[ frame_length ], 2 * sizeof( opus_int16 ) );
51 silk_memcpy( state->sSide, &x2[ frame_length ], 2 * sizeof( opus_int16 ) );
52
53 /* Interpolate predictors and add prediction to side channel */
54 pred0_Q13 = state->pred_prev_Q13[ 0 ];
55 pred1_Q13 = state->pred_prev_Q13[ 1 ];
56 denom_Q16 = silk_DIV32_16( (opus_int32)1 << 16, STEREO_INTERP_LEN_MS * fs_kHz );
57 delta0_Q13 = silk_RSHIFT_ROUND( silk_SMULBB( pred_Q13[ 0 ] - state->pred_prev_Q13[ 0 ], denom_Q16 ), 16 );
58 delta1_Q13 = silk_RSHIFT_ROUND( silk_SMULBB( pred_Q13[ 1 ] - state->pred_prev_Q13[ 1 ], denom_Q16 ), 16 );
59 for( n = 0; n < STEREO_INTERP_LEN_MS * fs_kHz; n++ ) {
60 pred0_Q13 += delta0_Q13;
61 pred1_Q13 += delta1_Q13;
62 sum = silk_LSHIFT( silk_ADD_LSHIFT32( x1[ n ] + (opus_int32)x1[ n + 2 ], x1[ n + 1 ], 1 ), 9 ); /* Q11 */
63 sum = silk_SMLAWB( silk_LSHIFT( (opus_int32)x2[ n + 1 ], 8 ), sum, pred0_Q13 ); /* Q8 */
64 sum = silk_SMLAWB( sum, silk_LSHIFT( (opus_int32)x1[ n + 1 ], 11 ), pred1_Q13 ); /* Q8 */
65 x2[ n + 1 ] = (opus_int16)silk_SAT16( silk_RSHIFT_ROUND( sum, 8 ) );
66 }
67 pred0_Q13 = pred_Q13[ 0 ];
68 pred1_Q13 = pred_Q13[ 1 ];
69 for( n = STEREO_INTERP_LEN_MS * fs_kHz; n < frame_length; n++ ) {
70 sum = silk_LSHIFT( silk_ADD_LSHIFT32( x1[ n ] + (opus_int32)x1[ n + 2 ], x1[ n + 1 ], 1 ), 9 ); /* Q11 */
71 sum = silk_SMLAWB( silk_LSHIFT( (opus_int32)x2[ n + 1 ], 8 ), sum, pred0_Q13 ); /* Q8 */
72 sum = silk_SMLAWB( sum, silk_LSHIFT( (opus_int32)x1[ n + 1 ], 11 ), pred1_Q13 ); /* Q8 */
73 x2[ n + 1 ] = (opus_int16)silk_SAT16( silk_RSHIFT_ROUND( sum, 8 ) );
74 }
75 state->pred_prev_Q13[ 0 ] = pred_Q13[ 0 ];
76 state->pred_prev_Q13[ 1 ] = pred_Q13[ 1 ];
77
78 /* Convert to left/right signals */
79 for( n = 0; n < frame_length; n++ ) {
80 sum = x1[ n + 1 ] + (opus_int32)x2[ n + 1 ];
81 diff = x1[ n + 1 ] - (opus_int32)x2[ n + 1 ];
82 x1[ n + 1 ] = (opus_int16)silk_SAT16( sum );
83 x2[ n + 1 ] = (opus_int16)silk_SAT16( diff );
84 }
85 }
86