/* * Audio Processing Technology codec for Bluetooth (aptX) * * Copyright (C) 2017 Aurelien Jacobs * * This file is part of FFmpeg. * * FFmpeg is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * FFmpeg is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with FFmpeg; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ #include "aptx.h" #include "mathops.h" static const int32_t quantize_intervals_LF[65] = { -9948, 9948, 29860, 49808, 69822, 89926, 110144, 130502, 151026, 171738, 192666, 213832, 235264, 256982, 279014, 301384, 324118, 347244, 370790, 394782, 419250, 444226, 469742, 495832, 522536, 549890, 577936, 606720, 636290, 666700, 698006, 730270, 763562, 797958, 833538, 870398, 908640, 948376, 989740, 1032874, 1077948, 1125150, 1174700, 1226850, 1281900, 1340196, 1402156, 1468282, 1539182, 1615610, 1698514, 1789098, 1888944, 2000168, 2125700, 2269750, 2438670, 2642660, 2899462, 3243240, 3746078, 4535138, 5664098, 7102424, 8897462, }; static const int32_t invert_quantize_dither_factors_LF[65] = { 9948, 9948, 9962, 9988, 10026, 10078, 10142, 10218, 10306, 10408, 10520, 10646, 10784, 10934, 11098, 11274, 11462, 11664, 11880, 12112, 12358, 12618, 12898, 13194, 13510, 13844, 14202, 14582, 14988, 15422, 15884, 16380, 16912, 17484, 18098, 18762, 19480, 20258, 21106, 22030, 23044, 24158, 25390, 26760, 28290, 30008, 31954, 34172, 36728, 39700, 43202, 47382, 52462, 58762, 66770, 77280, 91642, 112348, 144452, 199326, 303512, 485546, 643414, 794914, 1000124, }; static const int32_t quantize_dither_factors_LF[65] = { 0, 4, 7, 10, 13, 16, 19, 22, 26, 28, 32, 35, 38, 41, 44, 47, 51, 54, 58, 62, 65, 70, 74, 79, 84, 90, 95, 102, 109, 116, 124, 133, 143, 154, 166, 180, 195, 212, 231, 254, 279, 308, 343, 383, 430, 487, 555, 639, 743, 876, 1045, 1270, 1575, 2002, 2628, 3591, 5177, 8026, 13719, 26047, 45509, 39467, 37875, 51303, 0, }; static const int16_t quantize_factor_select_offset_LF[65] = { 0, -21, -19, -17, -15, -12, -10, -8, -6, -4, -1, 1, 3, 6, 8, 10, 13, 15, 18, 20, 23, 26, 29, 31, 34, 37, 40, 43, 47, 50, 53, 57, 60, 64, 68, 72, 76, 80, 85, 89, 94, 99, 105, 110, 116, 123, 129, 136, 144, 152, 161, 171, 182, 194, 207, 223, 241, 263, 291, 328, 382, 467, 522, 522, 522, }; static const int32_t quantize_intervals_MLF[9] = { -89806, 89806, 278502, 494338, 759442, 1113112, 1652322, 2720256, 5190186, }; static const int32_t invert_quantize_dither_factors_MLF[9] = { 89806, 89806, 98890, 116946, 148158, 205512, 333698, 734236, 1735696, }; static const int32_t quantize_dither_factors_MLF[9] = { 0, 2271, 4514, 7803, 14339, 32047, 100135, 250365, 0, }; static const int16_t quantize_factor_select_offset_MLF[9] = { 0, -14, 6, 29, 58, 96, 154, 270, 521, }; static const int32_t quantize_intervals_MHF[3] = { -194080, 194080, 890562, }; static const int32_t invert_quantize_dither_factors_MHF[3] = { 194080, 194080, 502402, }; static const int32_t quantize_dither_factors_MHF[3] = { 0, 77081, 0, }; static const int16_t quantize_factor_select_offset_MHF[3] = { 0, -33, 136, }; static const int32_t quantize_intervals_HF[5] = { -163006, 163006, 542708, 1120554, 2669238, }; static const int32_t invert_quantize_dither_factors_HF[5] = { 163006, 163006, 216698, 361148, 1187538, }; static const int32_t quantize_dither_factors_HF[5] = { 0, 13423, 36113, 206598, 0, }; static const int16_t quantize_factor_select_offset_HF[5] = { 0, -8, 33, 95, 262, }; static const int32_t hd_quantize_intervals_LF[257] = { -2436, 2436, 7308, 12180, 17054, 21930, 26806, 31686, 36566, 41450, 46338, 51230, 56124, 61024, 65928, 70836, 75750, 80670, 85598, 90530, 95470, 100418, 105372, 110336, 115308, 120288, 125278, 130276, 135286, 140304, 145334, 150374, 155426, 160490, 165566, 170654, 175756, 180870, 185998, 191138, 196294, 201466, 206650, 211850, 217068, 222300, 227548, 232814, 238096, 243396, 248714, 254050, 259406, 264778, 270172, 275584, 281018, 286470, 291944, 297440, 302956, 308496, 314056, 319640, 325248, 330878, 336532, 342212, 347916, 353644, 359398, 365178, 370986, 376820, 382680, 388568, 394486, 400430, 406404, 412408, 418442, 424506, 430600, 436726, 442884, 449074, 455298, 461554, 467844, 474168, 480528, 486922, 493354, 499820, 506324, 512866, 519446, 526064, 532722, 539420, 546160, 552940, 559760, 566624, 573532, 580482, 587478, 594520, 601606, 608740, 615920, 623148, 630426, 637754, 645132, 652560, 660042, 667576, 675164, 682808, 690506, 698262, 706074, 713946, 721876, 729868, 737920, 746036, 754216, 762460, 770770, 779148, 787594, 796108, 804694, 813354, 822086, 830892, 839774, 848736, 857776, 866896, 876100, 885386, 894758, 904218, 913766, 923406, 933138, 942964, 952886, 962908, 973030, 983254, 993582, 1004020, 1014566, 1025224, 1035996, 1046886, 1057894, 1069026, 1080284, 1091670, 1103186, 1114838, 1126628, 1138558, 1150634, 1162858, 1175236, 1187768, 1200462, 1213320, 1226346, 1239548, 1252928, 1266490, 1280242, 1294188, 1308334, 1322688, 1337252, 1352034, 1367044, 1382284, 1397766, 1413494, 1429478, 1445728, 1462252, 1479058, 1496158, 1513562, 1531280, 1549326, 1567710, 1586446, 1605550, 1625034, 1644914, 1665208, 1685932, 1707108, 1728754, 1750890, 1773542, 1796732, 1820488, 1844840, 1869816, 1895452, 1921780, 1948842, 1976680, 2005338, 2034868, 2065322, 2096766, 2129260, 2162880, 2197708, 2233832, 2271352, 2310384, 2351050, 2393498, 2437886, 2484404, 2533262, 2584710, 2639036, 2696578, 2757738, 2822998, 2892940, 2968278, 3049896, 3138912, 3236760, 3345312, 3467068, 3605434, 3765154, 3952904, 4177962, 4452178, 4787134, 5187290, 5647128, 6159120, 6720518, 7332904, 8000032, 8726664, 9518152, 10380372, }; static const int32_t hd_invert_quantize_dither_factors_LF[257] = { 2436, 2436, 2436, 2436, 2438, 2438, 2438, 2440, 2442, 2442, 2444, 2446, 2448, 2450, 2454, 2456, 2458, 2462, 2464, 2468, 2472, 2476, 2480, 2484, 2488, 2492, 2498, 2502, 2506, 2512, 2518, 2524, 2528, 2534, 2540, 2548, 2554, 2560, 2568, 2574, 2582, 2588, 2596, 2604, 2612, 2620, 2628, 2636, 2646, 2654, 2664, 2672, 2682, 2692, 2702, 2712, 2722, 2732, 2742, 2752, 2764, 2774, 2786, 2798, 2810, 2822, 2834, 2846, 2858, 2870, 2884, 2896, 2910, 2924, 2938, 2952, 2966, 2980, 2994, 3010, 3024, 3040, 3056, 3070, 3086, 3104, 3120, 3136, 3154, 3170, 3188, 3206, 3224, 3242, 3262, 3280, 3300, 3320, 3338, 3360, 3380, 3400, 3422, 3442, 3464, 3486, 3508, 3532, 3554, 3578, 3602, 3626, 3652, 3676, 3702, 3728, 3754, 3780, 3808, 3836, 3864, 3892, 3920, 3950, 3980, 4010, 4042, 4074, 4106, 4138, 4172, 4206, 4240, 4276, 4312, 4348, 4384, 4422, 4460, 4500, 4540, 4580, 4622, 4664, 4708, 4752, 4796, 4842, 4890, 4938, 4986, 5036, 5086, 5138, 5192, 5246, 5300, 5358, 5416, 5474, 5534, 5596, 5660, 5726, 5792, 5860, 5930, 6002, 6074, 6150, 6226, 6306, 6388, 6470, 6556, 6644, 6736, 6828, 6924, 7022, 7124, 7228, 7336, 7448, 7562, 7680, 7802, 7928, 8058, 8192, 8332, 8476, 8624, 8780, 8940, 9106, 9278, 9458, 9644, 9840, 10042, 10252, 10472, 10702, 10942, 11194, 11458, 11734, 12024, 12328, 12648, 12986, 13342, 13720, 14118, 14540, 14990, 15466, 15976, 16520, 17102, 17726, 18398, 19124, 19908, 20760, 21688, 22702, 23816, 25044, 26404, 27922, 29622, 31540, 33720, 36222, 39116, 42502, 46514, 51334, 57218, 64536, 73830, 85890, 101860, 123198, 151020, 183936, 216220, 243618, 268374, 293022, 319362, 347768, 378864, 412626, 449596, }; static const int32_t hd_quantize_dither_factors_LF[256] = { 0, 0, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 2, 3, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 5, 4, 4, 5, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 6, 5, 5, 6, 5, 6, 6, 6, 6, 6, 6, 6, 6, 7, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 9, 10, 10, 10, 10, 10, 11, 11, 11, 11, 11, 12, 12, 12, 12, 13, 13, 13, 14, 14, 14, 15, 15, 15, 15, 16, 16, 17, 17, 17, 18, 18, 18, 19, 19, 20, 21, 21, 22, 22, 23, 23, 24, 25, 26, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 39, 40, 42, 43, 45, 47, 49, 51, 53, 55, 58, 60, 63, 66, 69, 73, 76, 80, 85, 89, 95, 100, 106, 113, 119, 128, 136, 146, 156, 168, 182, 196, 213, 232, 254, 279, 307, 340, 380, 425, 480, 545, 626, 724, 847, 1003, 1205, 1471, 1830, 2324, 3015, 3993, 5335, 6956, 8229, 8071, 6850, 6189, 6162, 6585, 7102, 7774, 8441, 9243, }; static const int16_t hd_quantize_factor_select_offset_LF[257] = { 0, -22, -21, -21, -20, -20, -19, -19, -18, -18, -17, -17, -16, -16, -15, -14, -14, -13, -13, -12, -12, -11, -11, -10, -10, -9, -9, -8, -7, -7, -6, -6, -5, -5, -4, -4, -3, -3, -2, -1, -1, 0, 0, 1, 1, 2, 2, 3, 4, 4, 5, 5, 6, 6, 7, 8, 8, 9, 9, 10, 11, 11, 12, 12, 13, 14, 14, 15, 15, 16, 17, 17, 18, 19, 19, 20, 20, 21, 22, 22, 23, 24, 24, 25, 26, 26, 27, 28, 28, 29, 30, 30, 31, 32, 33, 33, 34, 35, 35, 36, 37, 38, 38, 39, 40, 41, 41, 42, 43, 44, 44, 45, 46, 47, 48, 48, 49, 50, 51, 52, 52, 53, 54, 55, 56, 57, 58, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 69, 70, 71, 72, 73, 74, 75, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 89, 90, 91, 92, 93, 94, 96, 97, 98, 99, 101, 102, 103, 105, 106, 107, 109, 110, 112, 113, 115, 116, 118, 119, 121, 122, 124, 125, 127, 129, 130, 132, 134, 136, 137, 139, 141, 143, 145, 147, 149, 151, 153, 155, 158, 160, 162, 164, 167, 169, 172, 174, 177, 180, 182, 185, 188, 191, 194, 197, 201, 204, 208, 211, 215, 219, 223, 227, 232, 236, 241, 246, 251, 257, 263, 269, 275, 283, 290, 298, 307, 317, 327, 339, 352, 367, 384, 404, 429, 458, 494, 522, 522, 522, 522, 522, 522, 522, 522, 522, }; static const int32_t hd_quantize_intervals_MLF[33] = { -21236, 21236, 63830, 106798, 150386, 194832, 240376, 287258, 335726, 386034, 438460, 493308, 550924, 611696, 676082, 744626, 817986, 896968, 982580, 1076118, 1179278, 1294344, 1424504, 1574386, 1751090, 1966260, 2240868, 2617662, 3196432, 4176450, 5658260, 7671068, 10380372, }; static const int32_t hd_invert_quantize_dither_factors_MLF[33] = { 21236, 21236, 21360, 21608, 21978, 22468, 23076, 23806, 24660, 25648, 26778, 28070, 29544, 31228, 33158, 35386, 37974, 41008, 44606, 48934, 54226, 60840, 69320, 80564, 96140, 119032, 155576, 221218, 357552, 622468, 859344, 1153464, 1555840, }; static const int32_t hd_quantize_dither_factors_MLF[32] = { 0, 31, 62, 93, 123, 152, 183, 214, 247, 283, 323, 369, 421, 483, 557, 647, 759, 900, 1082, 1323, 1654, 2120, 2811, 3894, 5723, 9136, 16411, 34084, 66229, 59219, 73530, 100594, }; static const int16_t hd_quantize_factor_select_offset_MLF[33] = { 0, -21, -16, -12, -7, -2, 3, 8, 13, 19, 24, 30, 36, 43, 50, 57, 65, 74, 83, 93, 104, 117, 131, 147, 166, 189, 219, 259, 322, 427, 521, 521, 521, }; static const int32_t hd_quantize_intervals_MHF[9] = { -95044, 95044, 295844, 528780, 821332, 1226438, 1890540, 3344850, 6450664, }; static const int32_t hd_invert_quantize_dither_factors_MHF[9] = { 95044, 95044, 105754, 127180, 165372, 39736, 424366, 1029946, 2075866, }; static const int32_t hd_quantize_dither_factors_MHF[8] = { 0, 2678, 5357, 9548, -31409, 96158, 151395, 261480, }; static const int16_t hd_quantize_factor_select_offset_MHF[9] = { 0, -17, 5, 30, 62, 105, 177, 334, 518, }; static const int32_t hd_quantize_intervals_HF[17] = { -45754, 45754, 138496, 234896, 337336, 448310, 570738, 708380, 866534, 1053262, 1281958, 1577438, 1993050, 2665984, 3900982, 5902844, 8897462, }; static const int32_t hd_invert_quantize_dither_factors_HF[17] = { 45754, 45754, 46988, 49412, 53026, 57950, 64478, 73164, 84988, 101740, 126958, 168522, 247092, 425842, 809154, 1192708, 1801910, }; static const int32_t hd_quantize_dither_factors_HF[16] = { 0, 309, 606, 904, 1231, 1632, 2172, 2956, 4188, 6305, 10391, 19643, 44688, 95828, 95889, 152301, }; static const int16_t hd_quantize_factor_select_offset_HF[17] = { 0, -18, -8, 2, 13, 25, 38, 53, 70, 90, 115, 147, 192, 264, 398, 521, 521, }; ConstTables ff_aptx_quant_tables[2][NB_SUBBANDS] = { { [LF] = { quantize_intervals_LF, invert_quantize_dither_factors_LF, quantize_dither_factors_LF, quantize_factor_select_offset_LF, FF_ARRAY_ELEMS(quantize_intervals_LF), 0x11FF, 24 }, [MLF] = { quantize_intervals_MLF, invert_quantize_dither_factors_MLF, quantize_dither_factors_MLF, quantize_factor_select_offset_MLF, FF_ARRAY_ELEMS(quantize_intervals_MLF), 0x14FF, 12 }, [MHF] = { quantize_intervals_MHF, invert_quantize_dither_factors_MHF, quantize_dither_factors_MHF, quantize_factor_select_offset_MHF, FF_ARRAY_ELEMS(quantize_intervals_MHF), 0x16FF, 6 }, [HF] = { quantize_intervals_HF, invert_quantize_dither_factors_HF, quantize_dither_factors_HF, quantize_factor_select_offset_HF, FF_ARRAY_ELEMS(quantize_intervals_HF), 0x15FF, 12 }, }, { [LF] = { hd_quantize_intervals_LF, hd_invert_quantize_dither_factors_LF, hd_quantize_dither_factors_LF, hd_quantize_factor_select_offset_LF, FF_ARRAY_ELEMS(hd_quantize_intervals_LF), 0x11FF, 24 }, [MLF] = { hd_quantize_intervals_MLF, hd_invert_quantize_dither_factors_MLF, hd_quantize_dither_factors_MLF, hd_quantize_factor_select_offset_MLF, FF_ARRAY_ELEMS(hd_quantize_intervals_MLF), 0x14FF, 12 }, [MHF] = { hd_quantize_intervals_MHF, hd_invert_quantize_dither_factors_MHF, hd_quantize_dither_factors_MHF, hd_quantize_factor_select_offset_MHF, FF_ARRAY_ELEMS(hd_quantize_intervals_MHF), 0x16FF, 6 }, [HF] = { hd_quantize_intervals_HF, hd_invert_quantize_dither_factors_HF, hd_quantize_dither_factors_HF, hd_quantize_factor_select_offset_HF, FF_ARRAY_ELEMS(hd_quantize_intervals_HF), 0x15FF, 12 }, } }; static const int16_t quantization_factors[32] = { 2048, 2093, 2139, 2186, 2233, 2282, 2332, 2383, 2435, 2489, 2543, 2599, 2656, 2714, 2774, 2834, 2896, 2960, 3025, 3091, 3158, 3228, 3298, 3371, 3444, 3520, 3597, 3676, 3756, 3838, 3922, 4008, }; av_always_inline static void aptx_update_codeword_history(Channel *channel) { int32_t cw = ((channel->quantize[0].quantized_sample & 3) << 0) + ((channel->quantize[1].quantized_sample & 2) << 1) + ((channel->quantize[2].quantized_sample & 1) << 3); channel->codeword_history = (cw << 8) + ((unsigned)channel->codeword_history << 4); } void ff_aptx_generate_dither(Channel *channel) { int subband; int64_t m; int32_t d; aptx_update_codeword_history(channel); m = (int64_t)5184443 * (channel->codeword_history >> 7); d = (m * 4) + (m >> 22); for (subband = 0; subband < NB_SUBBANDS; subband++) channel->dither[subband] = (unsigned)d << (23 - 5*subband); channel->dither_parity = (d >> 25) & 1; } static void aptx_invert_quantization(InvertQuantize *invert_quantize, int32_t quantized_sample, int32_t dither, ConstTables *tables) { int32_t qr, idx, shift, factor_select; idx = (quantized_sample ^ -(quantized_sample < 0)) + 1; qr = tables->quantize_intervals[idx] / 2; if (quantized_sample < 0) qr = -qr; qr = rshift64_clip24((qr * (1LL<<32)) + MUL64(dither, tables->invert_quantize_dither_factors[idx]), 32); invert_quantize->reconstructed_difference = MUL64(invert_quantize->quantization_factor, qr) >> 19; /* update factor_select */ factor_select = 32620 * invert_quantize->factor_select; factor_select = rshift32(factor_select + (tables->quantize_factor_select_offset[idx] * (1 << 15)), 15); invert_quantize->factor_select = av_clip(factor_select, 0, tables->factor_max); /* update quantization factor */ idx = (invert_quantize->factor_select & 0xFF) >> 3; shift = (tables->factor_max - invert_quantize->factor_select) >> 8; invert_quantize->quantization_factor = (quantization_factors[idx] << 11) >> shift; } static int32_t *aptx_reconstructed_differences_update(Prediction *prediction, int32_t reconstructed_difference, int order) { int32_t *rd1 = prediction->reconstructed_differences, *rd2 = rd1 + order; int p = prediction->pos; rd1[p] = rd2[p]; prediction->pos = p = (p + 1) % order; rd2[p] = reconstructed_difference; return &rd2[p]; } static void aptx_prediction_filtering(Prediction *prediction, int32_t reconstructed_difference, int order) { int32_t reconstructed_sample, predictor, srd0; int32_t *reconstructed_differences; int64_t predicted_difference = 0; int i; reconstructed_sample = av_clip_intp2(reconstructed_difference + prediction->predicted_sample, 23); predictor = av_clip_intp2((MUL64(prediction->s_weight[0], prediction->previous_reconstructed_sample) + MUL64(prediction->s_weight[1], reconstructed_sample)) >> 22, 23); prediction->previous_reconstructed_sample = reconstructed_sample; reconstructed_differences = aptx_reconstructed_differences_update(prediction, reconstructed_difference, order); srd0 = FFDIFFSIGN(reconstructed_difference, 0) * (1 << 23); for (i = 0; i < order; i++) { int32_t srd = FF_SIGNBIT(reconstructed_differences[-i-1]) | 1; prediction->d_weight[i] -= rshift32(prediction->d_weight[i] - srd*srd0, 8); predicted_difference += MUL64(reconstructed_differences[-i], prediction->d_weight[i]); } prediction->predicted_difference = av_clip_intp2(predicted_difference >> 22, 23); prediction->predicted_sample = av_clip_intp2(predictor + prediction->predicted_difference, 23); } static void aptx_process_subband(InvertQuantize *invert_quantize, Prediction *prediction, int32_t quantized_sample, int32_t dither, ConstTables *tables) { int32_t sign, same_sign[2], weight[2], sw1, range; aptx_invert_quantization(invert_quantize, quantized_sample, dither, tables); sign = FFDIFFSIGN(invert_quantize->reconstructed_difference, -prediction->predicted_difference); same_sign[0] = sign * prediction->prev_sign[0]; same_sign[1] = sign * prediction->prev_sign[1]; prediction->prev_sign[0] = prediction->prev_sign[1]; prediction->prev_sign[1] = sign | 1; range = 0x100000; sw1 = rshift32(-same_sign[1] * prediction->s_weight[1], 1); sw1 = (av_clip(sw1, -range, range) & ~0xF) * 16; range = 0x300000; weight[0] = 254 * prediction->s_weight[0] + 0x800000*same_sign[0] + sw1; prediction->s_weight[0] = av_clip(rshift32(weight[0], 8), -range, range); range = 0x3C0000 - prediction->s_weight[0]; weight[1] = 255 * prediction->s_weight[1] + 0xC00000*same_sign[1]; prediction->s_weight[1] = av_clip(rshift32(weight[1], 8), -range, range); aptx_prediction_filtering(prediction, invert_quantize->reconstructed_difference, tables->prediction_order); } void ff_aptx_invert_quantize_and_prediction(Channel *channel, int hd) { int subband; for (subband = 0; subband < NB_SUBBANDS; subband++) aptx_process_subband(&channel->invert_quantize[subband], &channel->prediction[subband], channel->quantize[subband].quantized_sample, channel->dither[subband], &ff_aptx_quant_tables[hd][subband]); } av_cold int ff_aptx_init(AVCodecContext *avctx) { AptXContext *s = avctx->priv_data; int chan, subband; if (avctx->ch_layout.nb_channels != 2) return AVERROR_INVALIDDATA; s->hd = avctx->codec->id == AV_CODEC_ID_APTX_HD; s->block_size = s->hd ? 6 : 4; for (chan = 0; chan < NB_CHANNELS; chan++) { Channel *channel = &s->channels[chan]; for (subband = 0; subband < NB_SUBBANDS; subband++) { Prediction *prediction = &channel->prediction[subband]; prediction->prev_sign[0] = 1; prediction->prev_sign[1] = 1; } } return 0; }