Vignesh Venkatasubramanian | 2bd8b54 | 2014-02-20 10:50:35 -0800 | [diff] [blame] | 1 | /*********************************************************************** |
| 2 | Copyright (c) 2006-2011, Skype Limited. All rights reserved. |
| 3 | Redistribution and use in source and binary forms, with or without |
| 4 | modification, are permitted provided that the following conditions |
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| 13 | products derived from this software without specific prior written |
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| 15 | THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
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| 26 | ***********************************************************************/ |
| 27 | |
| 28 | #ifdef HAVE_CONFIG_H |
| 29 | #include "config.h" |
| 30 | #endif |
| 31 | |
| 32 | #include "main.h" |
| 33 | #include "stack_alloc.h" |
| 34 | |
| 35 | /* Convert Left/Right stereo signal to adaptive Mid/Side representation */ |
| 36 | void silk_stereo_LR_to_MS( |
| 37 | stereo_enc_state *state, /* I/O State */ |
| 38 | opus_int16 x1[], /* I/O Left input signal, becomes mid signal */ |
| 39 | opus_int16 x2[], /* I/O Right input signal, becomes side signal */ |
| 40 | opus_int8 ix[ 2 ][ 3 ], /* O Quantization indices */ |
| 41 | opus_int8 *mid_only_flag, /* O Flag: only mid signal coded */ |
| 42 | opus_int32 mid_side_rates_bps[], /* O Bitrates for mid and side signals */ |
| 43 | opus_int32 total_rate_bps, /* I Total bitrate */ |
| 44 | opus_int prev_speech_act_Q8, /* I Speech activity level in previous frame */ |
| 45 | opus_int toMono, /* I Last frame before a stereo->mono transition */ |
| 46 | opus_int fs_kHz, /* I Sample rate (kHz) */ |
| 47 | opus_int frame_length /* I Number of samples */ |
| 48 | ) |
| 49 | { |
| 50 | opus_int n, is10msFrame, denom_Q16, delta0_Q13, delta1_Q13; |
| 51 | opus_int32 sum, diff, smooth_coef_Q16, pred_Q13[ 2 ], pred0_Q13, pred1_Q13; |
| 52 | opus_int32 LP_ratio_Q14, HP_ratio_Q14, frac_Q16, frac_3_Q16, min_mid_rate_bps, width_Q14, w_Q24, deltaw_Q24; |
| 53 | VARDECL( opus_int16, side ); |
| 54 | VARDECL( opus_int16, LP_mid ); |
| 55 | VARDECL( opus_int16, HP_mid ); |
| 56 | VARDECL( opus_int16, LP_side ); |
| 57 | VARDECL( opus_int16, HP_side ); |
| 58 | opus_int16 *mid = &x1[ -2 ]; |
| 59 | SAVE_STACK; |
| 60 | |
| 61 | ALLOC( side, frame_length + 2, opus_int16 ); |
| 62 | /* Convert to basic mid/side signals */ |
| 63 | for( n = 0; n < frame_length + 2; n++ ) { |
| 64 | sum = x1[ n - 2 ] + (opus_int32)x2[ n - 2 ]; |
| 65 | diff = x1[ n - 2 ] - (opus_int32)x2[ n - 2 ]; |
| 66 | mid[ n ] = (opus_int16)silk_RSHIFT_ROUND( sum, 1 ); |
| 67 | side[ n ] = (opus_int16)silk_SAT16( silk_RSHIFT_ROUND( diff, 1 ) ); |
| 68 | } |
| 69 | |
| 70 | /* Buffering */ |
| 71 | silk_memcpy( mid, state->sMid, 2 * sizeof( opus_int16 ) ); |
| 72 | silk_memcpy( side, state->sSide, 2 * sizeof( opus_int16 ) ); |
| 73 | silk_memcpy( state->sMid, &mid[ frame_length ], 2 * sizeof( opus_int16 ) ); |
| 74 | silk_memcpy( state->sSide, &side[ frame_length ], 2 * sizeof( opus_int16 ) ); |
| 75 | |
| 76 | /* LP and HP filter mid signal */ |
| 77 | ALLOC( LP_mid, frame_length, opus_int16 ); |
| 78 | ALLOC( HP_mid, frame_length, opus_int16 ); |
| 79 | for( n = 0; n < frame_length; n++ ) { |
Felicia Lim | d03c373 | 2016-07-25 20:28:37 +0200 | [diff] [blame] | 80 | sum = silk_RSHIFT_ROUND( silk_ADD_LSHIFT( mid[ n ] + (opus_int32)mid[ n + 2 ], mid[ n + 1 ], 1 ), 2 ); |
Vignesh Venkatasubramanian | 2bd8b54 | 2014-02-20 10:50:35 -0800 | [diff] [blame] | 81 | LP_mid[ n ] = sum; |
| 82 | HP_mid[ n ] = mid[ n + 1 ] - sum; |
| 83 | } |
| 84 | |
| 85 | /* LP and HP filter side signal */ |
| 86 | ALLOC( LP_side, frame_length, opus_int16 ); |
| 87 | ALLOC( HP_side, frame_length, opus_int16 ); |
| 88 | for( n = 0; n < frame_length; n++ ) { |
Felicia Lim | d03c373 | 2016-07-25 20:28:37 +0200 | [diff] [blame] | 89 | sum = silk_RSHIFT_ROUND( silk_ADD_LSHIFT( side[ n ] + (opus_int32)side[ n + 2 ], side[ n + 1 ], 1 ), 2 ); |
Vignesh Venkatasubramanian | 2bd8b54 | 2014-02-20 10:50:35 -0800 | [diff] [blame] | 90 | LP_side[ n ] = sum; |
| 91 | HP_side[ n ] = side[ n + 1 ] - sum; |
| 92 | } |
| 93 | |
| 94 | /* Find energies and predictors */ |
| 95 | is10msFrame = frame_length == 10 * fs_kHz; |
| 96 | smooth_coef_Q16 = is10msFrame ? |
| 97 | SILK_FIX_CONST( STEREO_RATIO_SMOOTH_COEF / 2, 16 ) : |
| 98 | SILK_FIX_CONST( STEREO_RATIO_SMOOTH_COEF, 16 ); |
| 99 | smooth_coef_Q16 = silk_SMULWB( silk_SMULBB( prev_speech_act_Q8, prev_speech_act_Q8 ), smooth_coef_Q16 ); |
| 100 | |
| 101 | pred_Q13[ 0 ] = silk_stereo_find_predictor( &LP_ratio_Q14, LP_mid, LP_side, &state->mid_side_amp_Q0[ 0 ], frame_length, smooth_coef_Q16 ); |
| 102 | pred_Q13[ 1 ] = silk_stereo_find_predictor( &HP_ratio_Q14, HP_mid, HP_side, &state->mid_side_amp_Q0[ 2 ], frame_length, smooth_coef_Q16 ); |
| 103 | /* Ratio of the norms of residual and mid signals */ |
| 104 | frac_Q16 = silk_SMLABB( HP_ratio_Q14, LP_ratio_Q14, 3 ); |
| 105 | frac_Q16 = silk_min( frac_Q16, SILK_FIX_CONST( 1, 16 ) ); |
| 106 | |
| 107 | /* Determine bitrate distribution between mid and side, and possibly reduce stereo width */ |
| 108 | total_rate_bps -= is10msFrame ? 1200 : 600; /* Subtract approximate bitrate for coding stereo parameters */ |
| 109 | if( total_rate_bps < 1 ) { |
| 110 | total_rate_bps = 1; |
| 111 | } |
| 112 | min_mid_rate_bps = silk_SMLABB( 2000, fs_kHz, 900 ); |
| 113 | silk_assert( min_mid_rate_bps < 32767 ); |
| 114 | /* Default bitrate distribution: 8 parts for Mid and (5+3*frac) parts for Side. so: mid_rate = ( 8 / ( 13 + 3 * frac ) ) * total_ rate */ |
| 115 | frac_3_Q16 = silk_MUL( 3, frac_Q16 ); |
| 116 | mid_side_rates_bps[ 0 ] = silk_DIV32_varQ( total_rate_bps, SILK_FIX_CONST( 8 + 5, 16 ) + frac_3_Q16, 16+3 ); |
| 117 | /* If Mid bitrate below minimum, reduce stereo width */ |
| 118 | if( mid_side_rates_bps[ 0 ] < min_mid_rate_bps ) { |
| 119 | mid_side_rates_bps[ 0 ] = min_mid_rate_bps; |
| 120 | mid_side_rates_bps[ 1 ] = total_rate_bps - mid_side_rates_bps[ 0 ]; |
| 121 | /* width = 4 * ( 2 * side_rate - min_rate ) / ( ( 1 + 3 * frac ) * min_rate ) */ |
| 122 | width_Q14 = silk_DIV32_varQ( silk_LSHIFT( mid_side_rates_bps[ 1 ], 1 ) - min_mid_rate_bps, |
| 123 | silk_SMULWB( SILK_FIX_CONST( 1, 16 ) + frac_3_Q16, min_mid_rate_bps ), 14+2 ); |
| 124 | width_Q14 = silk_LIMIT( width_Q14, 0, SILK_FIX_CONST( 1, 14 ) ); |
| 125 | } else { |
| 126 | mid_side_rates_bps[ 1 ] = total_rate_bps - mid_side_rates_bps[ 0 ]; |
| 127 | width_Q14 = SILK_FIX_CONST( 1, 14 ); |
| 128 | } |
| 129 | |
| 130 | /* Smoother */ |
| 131 | state->smth_width_Q14 = (opus_int16)silk_SMLAWB( state->smth_width_Q14, width_Q14 - state->smth_width_Q14, smooth_coef_Q16 ); |
| 132 | |
| 133 | /* At very low bitrates or for inputs that are nearly amplitude panned, switch to panned-mono coding */ |
| 134 | *mid_only_flag = 0; |
| 135 | if( toMono ) { |
| 136 | /* Last frame before stereo->mono transition; collapse stereo width */ |
| 137 | width_Q14 = 0; |
| 138 | pred_Q13[ 0 ] = 0; |
| 139 | pred_Q13[ 1 ] = 0; |
| 140 | silk_stereo_quant_pred( pred_Q13, ix ); |
| 141 | } else if( state->width_prev_Q14 == 0 && |
| 142 | ( 8 * total_rate_bps < 13 * min_mid_rate_bps || silk_SMULWB( frac_Q16, state->smth_width_Q14 ) < SILK_FIX_CONST( 0.05, 14 ) ) ) |
| 143 | { |
| 144 | /* Code as panned-mono; previous frame already had zero width */ |
| 145 | /* Scale down and quantize predictors */ |
| 146 | pred_Q13[ 0 ] = silk_RSHIFT( silk_SMULBB( state->smth_width_Q14, pred_Q13[ 0 ] ), 14 ); |
| 147 | pred_Q13[ 1 ] = silk_RSHIFT( silk_SMULBB( state->smth_width_Q14, pred_Q13[ 1 ] ), 14 ); |
| 148 | silk_stereo_quant_pred( pred_Q13, ix ); |
| 149 | /* Collapse stereo width */ |
| 150 | width_Q14 = 0; |
| 151 | pred_Q13[ 0 ] = 0; |
| 152 | pred_Q13[ 1 ] = 0; |
| 153 | mid_side_rates_bps[ 0 ] = total_rate_bps; |
| 154 | mid_side_rates_bps[ 1 ] = 0; |
| 155 | *mid_only_flag = 1; |
| 156 | } else if( state->width_prev_Q14 != 0 && |
| 157 | ( 8 * total_rate_bps < 11 * min_mid_rate_bps || silk_SMULWB( frac_Q16, state->smth_width_Q14 ) < SILK_FIX_CONST( 0.02, 14 ) ) ) |
| 158 | { |
| 159 | /* Transition to zero-width stereo */ |
| 160 | /* Scale down and quantize predictors */ |
| 161 | pred_Q13[ 0 ] = silk_RSHIFT( silk_SMULBB( state->smth_width_Q14, pred_Q13[ 0 ] ), 14 ); |
| 162 | pred_Q13[ 1 ] = silk_RSHIFT( silk_SMULBB( state->smth_width_Q14, pred_Q13[ 1 ] ), 14 ); |
| 163 | silk_stereo_quant_pred( pred_Q13, ix ); |
| 164 | /* Collapse stereo width */ |
| 165 | width_Q14 = 0; |
| 166 | pred_Q13[ 0 ] = 0; |
| 167 | pred_Q13[ 1 ] = 0; |
| 168 | } else if( state->smth_width_Q14 > SILK_FIX_CONST( 0.95, 14 ) ) { |
| 169 | /* Full-width stereo coding */ |
| 170 | silk_stereo_quant_pred( pred_Q13, ix ); |
| 171 | width_Q14 = SILK_FIX_CONST( 1, 14 ); |
| 172 | } else { |
| 173 | /* Reduced-width stereo coding; scale down and quantize predictors */ |
| 174 | pred_Q13[ 0 ] = silk_RSHIFT( silk_SMULBB( state->smth_width_Q14, pred_Q13[ 0 ] ), 14 ); |
| 175 | pred_Q13[ 1 ] = silk_RSHIFT( silk_SMULBB( state->smth_width_Q14, pred_Q13[ 1 ] ), 14 ); |
| 176 | silk_stereo_quant_pred( pred_Q13, ix ); |
| 177 | width_Q14 = state->smth_width_Q14; |
| 178 | } |
| 179 | |
| 180 | /* Make sure to keep on encoding until the tapered output has been transmitted */ |
| 181 | if( *mid_only_flag == 1 ) { |
| 182 | state->silent_side_len += frame_length - STEREO_INTERP_LEN_MS * fs_kHz; |
| 183 | if( state->silent_side_len < LA_SHAPE_MS * fs_kHz ) { |
| 184 | *mid_only_flag = 0; |
| 185 | } else { |
| 186 | /* Limit to avoid wrapping around */ |
| 187 | state->silent_side_len = 10000; |
| 188 | } |
| 189 | } else { |
| 190 | state->silent_side_len = 0; |
| 191 | } |
| 192 | |
| 193 | if( *mid_only_flag == 0 && mid_side_rates_bps[ 1 ] < 1 ) { |
| 194 | mid_side_rates_bps[ 1 ] = 1; |
| 195 | mid_side_rates_bps[ 0 ] = silk_max_int( 1, total_rate_bps - mid_side_rates_bps[ 1 ]); |
| 196 | } |
| 197 | |
| 198 | /* Interpolate predictors and subtract prediction from side channel */ |
| 199 | pred0_Q13 = -state->pred_prev_Q13[ 0 ]; |
| 200 | pred1_Q13 = -state->pred_prev_Q13[ 1 ]; |
| 201 | w_Q24 = silk_LSHIFT( state->width_prev_Q14, 10 ); |
| 202 | denom_Q16 = silk_DIV32_16( (opus_int32)1 << 16, STEREO_INTERP_LEN_MS * fs_kHz ); |
| 203 | delta0_Q13 = -silk_RSHIFT_ROUND( silk_SMULBB( pred_Q13[ 0 ] - state->pred_prev_Q13[ 0 ], denom_Q16 ), 16 ); |
| 204 | delta1_Q13 = -silk_RSHIFT_ROUND( silk_SMULBB( pred_Q13[ 1 ] - state->pred_prev_Q13[ 1 ], denom_Q16 ), 16 ); |
| 205 | deltaw_Q24 = silk_LSHIFT( silk_SMULWB( width_Q14 - state->width_prev_Q14, denom_Q16 ), 10 ); |
| 206 | for( n = 0; n < STEREO_INTERP_LEN_MS * fs_kHz; n++ ) { |
| 207 | pred0_Q13 += delta0_Q13; |
| 208 | pred1_Q13 += delta1_Q13; |
| 209 | w_Q24 += deltaw_Q24; |
Felicia Lim | d03c373 | 2016-07-25 20:28:37 +0200 | [diff] [blame] | 210 | sum = silk_LSHIFT( silk_ADD_LSHIFT( mid[ n ] + (opus_int32)mid[ n + 2 ], mid[ n + 1 ], 1 ), 9 ); /* Q11 */ |
Vignesh Venkatasubramanian | 2bd8b54 | 2014-02-20 10:50:35 -0800 | [diff] [blame] | 211 | sum = silk_SMLAWB( silk_SMULWB( w_Q24, side[ n + 1 ] ), sum, pred0_Q13 ); /* Q8 */ |
| 212 | sum = silk_SMLAWB( sum, silk_LSHIFT( (opus_int32)mid[ n + 1 ], 11 ), pred1_Q13 ); /* Q8 */ |
| 213 | x2[ n - 1 ] = (opus_int16)silk_SAT16( silk_RSHIFT_ROUND( sum, 8 ) ); |
| 214 | } |
| 215 | |
| 216 | pred0_Q13 = -pred_Q13[ 0 ]; |
| 217 | pred1_Q13 = -pred_Q13[ 1 ]; |
| 218 | w_Q24 = silk_LSHIFT( width_Q14, 10 ); |
| 219 | for( n = STEREO_INTERP_LEN_MS * fs_kHz; n < frame_length; n++ ) { |
Felicia Lim | d03c373 | 2016-07-25 20:28:37 +0200 | [diff] [blame] | 220 | sum = silk_LSHIFT( silk_ADD_LSHIFT( mid[ n ] + (opus_int32)mid[ n + 2 ], mid[ n + 1 ], 1 ), 9 ); /* Q11 */ |
Vignesh Venkatasubramanian | 2bd8b54 | 2014-02-20 10:50:35 -0800 | [diff] [blame] | 221 | sum = silk_SMLAWB( silk_SMULWB( w_Q24, side[ n + 1 ] ), sum, pred0_Q13 ); /* Q8 */ |
| 222 | sum = silk_SMLAWB( sum, silk_LSHIFT( (opus_int32)mid[ n + 1 ], 11 ), pred1_Q13 ); /* Q8 */ |
| 223 | x2[ n - 1 ] = (opus_int16)silk_SAT16( silk_RSHIFT_ROUND( sum, 8 ) ); |
| 224 | } |
| 225 | state->pred_prev_Q13[ 0 ] = (opus_int16)pred_Q13[ 0 ]; |
| 226 | state->pred_prev_Q13[ 1 ] = (opus_int16)pred_Q13[ 1 ]; |
| 227 | state->width_prev_Q14 = (opus_int16)width_Q14; |
| 228 | RESTORE_STACK; |
| 229 | } |