/src/opus/silk/stereo_LR_to_MS.c
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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 |
5 | | are met: |
6 | | - Redistributions of source code must retain the above copyright notice, |
7 | | this list of conditions and the following disclaimer. |
8 | | - Redistributions in binary form must reproduce the above copyright |
9 | | notice, this list of conditions and the following disclaimer in the |
10 | | documentation and/or other materials provided with the distribution. |
11 | | - Neither the name of Internet Society, IETF or IETF Trust, nor the |
12 | | names of specific contributors, may be used to endorse or promote |
13 | | products derived from this software without specific prior written |
14 | | permission. |
15 | | THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
16 | | AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
17 | | IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
18 | | ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE |
19 | | LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
20 | | CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
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22 | | INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
23 | | CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
24 | | ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
25 | | POSSIBILITY OF SUCH DAMAGE. |
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 | 0 | { |
50 | 0 | opus_int n, is10msFrame, denom_Q16, delta0_Q13, delta1_Q13; |
51 | 0 | opus_int32 sum, diff, smooth_coef_Q16, pred_Q13[ 2 ], pred0_Q13, pred1_Q13; |
52 | 0 | opus_int32 LP_ratio_Q14, HP_ratio_Q14, frac_Q16, frac_3_Q16, min_mid_rate_bps, width_Q14, w_Q24, deltaw_Q24; |
53 | 0 | VARDECL( opus_int16, side ); |
54 | 0 | VARDECL( opus_int16, LP_mid ); |
55 | 0 | VARDECL( opus_int16, HP_mid ); |
56 | 0 | VARDECL( opus_int16, LP_side ); |
57 | 0 | VARDECL( opus_int16, HP_side ); |
58 | 0 | opus_int16 *mid = &x1[ -2 ]; |
59 | 0 | SAVE_STACK; |
60 | |
|
61 | 0 | ALLOC( side, frame_length + 2, opus_int16 ); |
62 | | /* Convert to basic mid/side signals */ |
63 | 0 | for( n = 0; n < frame_length + 2; n++ ) { |
64 | 0 | sum = x1[ n - 2 ] + (opus_int32)x2[ n - 2 ]; |
65 | 0 | diff = x1[ n - 2 ] - (opus_int32)x2[ n - 2 ]; |
66 | 0 | mid[ n ] = (opus_int16)silk_RSHIFT_ROUND( sum, 1 ); |
67 | 0 | side[ n ] = (opus_int16)silk_SAT16( silk_RSHIFT_ROUND( diff, 1 ) ); |
68 | 0 | } |
69 | | |
70 | | /* Buffering */ |
71 | 0 | silk_memcpy( mid, state->sMid, 2 * sizeof( opus_int16 ) ); |
72 | 0 | silk_memcpy( side, state->sSide, 2 * sizeof( opus_int16 ) ); |
73 | 0 | silk_memcpy( state->sMid, &mid[ frame_length ], 2 * sizeof( opus_int16 ) ); |
74 | 0 | silk_memcpy( state->sSide, &side[ frame_length ], 2 * sizeof( opus_int16 ) ); |
75 | | |
76 | | /* LP and HP filter mid signal */ |
77 | 0 | ALLOC( LP_mid, frame_length, opus_int16 ); |
78 | 0 | ALLOC( HP_mid, frame_length, opus_int16 ); |
79 | 0 | for( n = 0; n < frame_length; n++ ) { |
80 | 0 | sum = silk_RSHIFT_ROUND( silk_ADD_LSHIFT32( mid[ n ] + (opus_int32)mid[ n + 2 ], mid[ n + 1 ], 1 ), 2 ); |
81 | 0 | LP_mid[ n ] = sum; |
82 | 0 | HP_mid[ n ] = mid[ n + 1 ] - sum; |
83 | 0 | } |
84 | | |
85 | | /* LP and HP filter side signal */ |
86 | 0 | ALLOC( LP_side, frame_length, opus_int16 ); |
87 | 0 | ALLOC( HP_side, frame_length, opus_int16 ); |
88 | 0 | for( n = 0; n < frame_length; n++ ) { |
89 | 0 | sum = silk_RSHIFT_ROUND( silk_ADD_LSHIFT32( side[ n ] + (opus_int32)side[ n + 2 ], side[ n + 1 ], 1 ), 2 ); |
90 | 0 | LP_side[ n ] = sum; |
91 | 0 | HP_side[ n ] = side[ n + 1 ] - sum; |
92 | 0 | } |
93 | | |
94 | | /* Find energies and predictors */ |
95 | 0 | is10msFrame = frame_length == 10 * fs_kHz; |
96 | 0 | smooth_coef_Q16 = is10msFrame ? |
97 | 0 | SILK_FIX_CONST( STEREO_RATIO_SMOOTH_COEF / 2, 16 ) : |
98 | 0 | SILK_FIX_CONST( STEREO_RATIO_SMOOTH_COEF, 16 ); |
99 | 0 | smooth_coef_Q16 = silk_SMULWB( silk_SMULBB( prev_speech_act_Q8, prev_speech_act_Q8 ), smooth_coef_Q16 ); |
100 | |
|
101 | 0 | 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 | 0 | 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 | 0 | frac_Q16 = silk_SMLABB( HP_ratio_Q14, LP_ratio_Q14, 3 ); |
105 | 0 | 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 | 0 | total_rate_bps -= is10msFrame ? 1200 : 600; /* Subtract approximate bitrate for coding stereo parameters */ |
109 | 0 | if( total_rate_bps < 1 ) { |
110 | 0 | total_rate_bps = 1; |
111 | 0 | } |
112 | 0 | min_mid_rate_bps = silk_SMLABB( 2000, fs_kHz, 600 ); |
113 | 0 | 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 | 0 | frac_3_Q16 = silk_MUL( 3, frac_Q16 ); |
116 | 0 | 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 | 0 | if( mid_side_rates_bps[ 0 ] < min_mid_rate_bps ) { |
119 | 0 | mid_side_rates_bps[ 0 ] = min_mid_rate_bps; |
120 | 0 | 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 | 0 | width_Q14 = silk_DIV32_varQ( silk_LSHIFT( mid_side_rates_bps[ 1 ], 1 ) - min_mid_rate_bps, |
123 | 0 | silk_SMULWB( SILK_FIX_CONST( 1, 16 ) + frac_3_Q16, min_mid_rate_bps ), 14+2 ); |
124 | 0 | width_Q14 = silk_LIMIT( width_Q14, 0, SILK_FIX_CONST( 1, 14 ) ); |
125 | 0 | } else { |
126 | 0 | mid_side_rates_bps[ 1 ] = total_rate_bps - mid_side_rates_bps[ 0 ]; |
127 | 0 | width_Q14 = SILK_FIX_CONST( 1, 14 ); |
128 | 0 | } |
129 | | |
130 | | /* Smoother */ |
131 | 0 | 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 | 0 | *mid_only_flag = 0; |
135 | 0 | if( toMono ) { |
136 | | /* Last frame before stereo->mono transition; collapse stereo width */ |
137 | 0 | width_Q14 = 0; |
138 | 0 | pred_Q13[ 0 ] = 0; |
139 | 0 | pred_Q13[ 1 ] = 0; |
140 | 0 | silk_stereo_quant_pred( pred_Q13, ix ); |
141 | 0 | } else if( state->width_prev_Q14 == 0 && |
142 | 0 | ( 8 * total_rate_bps < 13 * min_mid_rate_bps || silk_SMULWB( frac_Q16, state->smth_width_Q14 ) < SILK_FIX_CONST( 0.05, 14 ) ) ) |
143 | 0 | { |
144 | | /* Code as panned-mono; previous frame already had zero width */ |
145 | | /* Scale down and quantize predictors */ |
146 | 0 | pred_Q13[ 0 ] = silk_RSHIFT( silk_SMULBB( state->smth_width_Q14, pred_Q13[ 0 ] ), 14 ); |
147 | 0 | pred_Q13[ 1 ] = silk_RSHIFT( silk_SMULBB( state->smth_width_Q14, pred_Q13[ 1 ] ), 14 ); |
148 | 0 | silk_stereo_quant_pred( pred_Q13, ix ); |
149 | | /* Collapse stereo width */ |
150 | 0 | width_Q14 = 0; |
151 | 0 | pred_Q13[ 0 ] = 0; |
152 | 0 | pred_Q13[ 1 ] = 0; |
153 | 0 | mid_side_rates_bps[ 0 ] = total_rate_bps; |
154 | 0 | mid_side_rates_bps[ 1 ] = 0; |
155 | 0 | *mid_only_flag = 1; |
156 | 0 | } else if( state->width_prev_Q14 != 0 && |
157 | 0 | ( 8 * total_rate_bps < 11 * min_mid_rate_bps || silk_SMULWB( frac_Q16, state->smth_width_Q14 ) < SILK_FIX_CONST( 0.02, 14 ) ) ) |
158 | 0 | { |
159 | | /* Transition to zero-width stereo */ |
160 | | /* Scale down and quantize predictors */ |
161 | 0 | pred_Q13[ 0 ] = silk_RSHIFT( silk_SMULBB( state->smth_width_Q14, pred_Q13[ 0 ] ), 14 ); |
162 | 0 | pred_Q13[ 1 ] = silk_RSHIFT( silk_SMULBB( state->smth_width_Q14, pred_Q13[ 1 ] ), 14 ); |
163 | 0 | silk_stereo_quant_pred( pred_Q13, ix ); |
164 | | /* Collapse stereo width */ |
165 | 0 | width_Q14 = 0; |
166 | 0 | pred_Q13[ 0 ] = 0; |
167 | 0 | pred_Q13[ 1 ] = 0; |
168 | 0 | } else if( state->smth_width_Q14 > SILK_FIX_CONST( 0.95, 14 ) ) { |
169 | | /* Full-width stereo coding */ |
170 | 0 | silk_stereo_quant_pred( pred_Q13, ix ); |
171 | 0 | width_Q14 = SILK_FIX_CONST( 1, 14 ); |
172 | 0 | } else { |
173 | | /* Reduced-width stereo coding; scale down and quantize predictors */ |
174 | 0 | pred_Q13[ 0 ] = silk_RSHIFT( silk_SMULBB( state->smth_width_Q14, pred_Q13[ 0 ] ), 14 ); |
175 | 0 | pred_Q13[ 1 ] = silk_RSHIFT( silk_SMULBB( state->smth_width_Q14, pred_Q13[ 1 ] ), 14 ); |
176 | 0 | silk_stereo_quant_pred( pred_Q13, ix ); |
177 | 0 | width_Q14 = state->smth_width_Q14; |
178 | 0 | } |
179 | | |
180 | | /* Make sure to keep on encoding until the tapered output has been transmitted */ |
181 | 0 | if( *mid_only_flag == 1 ) { |
182 | 0 | state->silent_side_len += frame_length - STEREO_INTERP_LEN_MS * fs_kHz; |
183 | 0 | if( state->silent_side_len < LA_SHAPE_MS * fs_kHz ) { |
184 | 0 | *mid_only_flag = 0; |
185 | 0 | } else { |
186 | | /* Limit to avoid wrapping around */ |
187 | 0 | state->silent_side_len = 10000; |
188 | 0 | } |
189 | 0 | } else { |
190 | 0 | state->silent_side_len = 0; |
191 | 0 | } |
192 | |
|
193 | 0 | if( *mid_only_flag == 0 && mid_side_rates_bps[ 1 ] < 1 ) { |
194 | 0 | mid_side_rates_bps[ 1 ] = 1; |
195 | 0 | mid_side_rates_bps[ 0 ] = silk_max_int( 1, total_rate_bps - mid_side_rates_bps[ 1 ]); |
196 | 0 | } |
197 | | |
198 | | /* Interpolate predictors and subtract prediction from side channel */ |
199 | 0 | pred0_Q13 = -state->pred_prev_Q13[ 0 ]; |
200 | 0 | pred1_Q13 = -state->pred_prev_Q13[ 1 ]; |
201 | 0 | w_Q24 = silk_LSHIFT( state->width_prev_Q14, 10 ); |
202 | 0 | denom_Q16 = silk_DIV32_16( (opus_int32)1 << 16, STEREO_INTERP_LEN_MS * fs_kHz ); |
203 | 0 | delta0_Q13 = -silk_RSHIFT_ROUND( silk_SMULBB( pred_Q13[ 0 ] - state->pred_prev_Q13[ 0 ], denom_Q16 ), 16 ); |
204 | 0 | delta1_Q13 = -silk_RSHIFT_ROUND( silk_SMULBB( pred_Q13[ 1 ] - state->pred_prev_Q13[ 1 ], denom_Q16 ), 16 ); |
205 | 0 | deltaw_Q24 = silk_LSHIFT( silk_SMULWB( width_Q14 - state->width_prev_Q14, denom_Q16 ), 10 ); |
206 | 0 | for( n = 0; n < STEREO_INTERP_LEN_MS * fs_kHz; n++ ) { |
207 | 0 | pred0_Q13 += delta0_Q13; |
208 | 0 | pred1_Q13 += delta1_Q13; |
209 | 0 | w_Q24 += deltaw_Q24; |
210 | 0 | sum = silk_LSHIFT( silk_ADD_LSHIFT32( mid[ n ] + (opus_int32)mid[ n + 2 ], mid[ n + 1 ], 1 ), 9 ); /* Q11 */ |
211 | 0 | sum = silk_SMLAWB( silk_SMULWB( w_Q24, side[ n + 1 ] ), sum, pred0_Q13 ); /* Q8 */ |
212 | 0 | sum = silk_SMLAWB( sum, silk_LSHIFT( (opus_int32)mid[ n + 1 ], 11 ), pred1_Q13 ); /* Q8 */ |
213 | 0 | x2[ n - 1 ] = (opus_int16)silk_SAT16( silk_RSHIFT_ROUND( sum, 8 ) ); |
214 | 0 | } |
215 | |
|
216 | 0 | pred0_Q13 = -pred_Q13[ 0 ]; |
217 | 0 | pred1_Q13 = -pred_Q13[ 1 ]; |
218 | 0 | w_Q24 = silk_LSHIFT( width_Q14, 10 ); |
219 | 0 | for( n = STEREO_INTERP_LEN_MS * fs_kHz; n < frame_length; n++ ) { |
220 | 0 | sum = silk_LSHIFT( silk_ADD_LSHIFT32( mid[ n ] + (opus_int32)mid[ n + 2 ], mid[ n + 1 ], 1 ), 9 ); /* Q11 */ |
221 | 0 | sum = silk_SMLAWB( silk_SMULWB( w_Q24, side[ n + 1 ] ), sum, pred0_Q13 ); /* Q8 */ |
222 | 0 | sum = silk_SMLAWB( sum, silk_LSHIFT( (opus_int32)mid[ n + 1 ], 11 ), pred1_Q13 ); /* Q8 */ |
223 | 0 | x2[ n - 1 ] = (opus_int16)silk_SAT16( silk_RSHIFT_ROUND( sum, 8 ) ); |
224 | 0 | } |
225 | 0 | state->pred_prev_Q13[ 0 ] = (opus_int16)pred_Q13[ 0 ]; |
226 | 0 | state->pred_prev_Q13[ 1 ] = (opus_int16)pred_Q13[ 1 ]; |
227 | 0 | state->width_prev_Q14 = (opus_int16)width_Q14; |
228 | 0 | RESTORE_STACK; |
229 | 0 | } |