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FFmpeg/libavcodec/aptx.c

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  1. /*

  2.  * Audio Processing Technology codec for Bluetooth (aptX)

  3.  *

  4.  * Copyright (C) 2017  Aurelien Jacobs <aurel@gnuage.org>

  5.  *

  6.  * This file is part of FFmpeg.

  7.  *

  8.  * FFmpeg is free software; you can redistribute it and/or

  9.  * modify it under the terms of the GNU Lesser General Public

  10.  * License as published by the Free Software Foundation; either

  11.  * version 2.1 of the License, or (at your option) any later version.

  12.  *

  13.  * FFmpeg is distributed in the hope that it will be useful,

  14.  * but WITHOUT ANY WARRANTY; without even the implied warranty of

  15.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

  16.  * Lesser General Public License for more details.

  17.  *

  18.  * You should have received a copy of the GNU Lesser General Public

  19.  * License along with FFmpeg; if not, write to the Free Software

  20.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

  21.  */

  22. 

  23. #include "libavutil/intreadwrite.h"

  24. #include "avcodec.h"

  25. #include "internal.h"

  26. #include "mathops.h"

  27. #include "audio_frame_queue.h"

  28. 

  29. 

  30. enum channels {

  31.     LEFT,

  32.     RIGHT,

  33.     NB_CHANNELS

  34. };

  35. 

  36. enum subbands {

  37.     LF,  // Low Frequency (0-5.5 kHz)

  38.     MLF, // Medium-Low Frequency (5.5-11kHz)

  39.     MHF, // Medium-High Frequency (11-16.5kHz)

  40.     HF,  // High Frequency (16.5-22kHz)

  41.     NB_SUBBANDS

  42. };

  43. 

  44. #define NB_FILTERS 2

  45. #define FILTER_TAPS 16

  46. 

  47. typedef struct {

  48.     int pos;

  49.     int32_t buffer[2*FILTER_TAPS];

  50. } FilterSignal;

  51. 

  52. typedef struct {

  53.     FilterSignal outer_filter_signal[NB_FILTERS];

  54.     FilterSignal inner_filter_signal[NB_FILTERS][NB_FILTERS];

  55. } QMFAnalysis;

  56. 

  57. typedef struct {

  58.     int32_t quantized_sample;

  59.     int32_t quantized_sample_parity_change;

  60.     int32_t error;

  61. } Quantize;

  62. 

  63. typedef struct {

  64.     int32_t quantization_factor;

  65.     int32_t factor_select;

  66.     int32_t reconstructed_difference;

  67. } InvertQuantize;

  68. 

  69. typedef struct {

  70.     int32_t prev_sign[2];

  71.     int32_t s_weight[2];

  72.     int32_t d_weight[24];

  73.     int32_t pos;

  74.     int32_t reconstructed_differences[48];

  75.     int32_t previous_reconstructed_sample;

  76.     int32_t predicted_difference;

  77.     int32_t predicted_sample;

  78. } Prediction;

  79. 

  80. typedef struct {

  81.     int32_t codeword_history;

  82.     int32_t dither_parity;

  83.     int32_t dither[NB_SUBBANDS];

  84. 

  85.     QMFAnalysis qmf;

  86.     Quantize quantize[NB_SUBBANDS];

  87.     InvertQuantize invert_quantize[NB_SUBBANDS];

  88.     Prediction prediction[NB_SUBBANDS];

  89. } Channel;

  90. 

  91. typedef struct {

  92.     int32_t sync_idx;

  93.     Channel channels[NB_CHANNELS];

  94.     AudioFrameQueue afq;

  95. } AptXContext;

  96. 

  97. 

  98. static const int32_t quantize_intervals_LF[65] = {

  99.       -9948,    9948,   29860,   49808,   69822,   89926,  110144,  130502,

  100.      151026,  171738,  192666,  213832,  235264,  256982,  279014,  301384,

  101.      324118,  347244,  370790,  394782,  419250,  444226,  469742,  495832,

  102.      522536,  549890,  577936,  606720,  636290,  666700,  698006,  730270,

  103.      763562,  797958,  833538,  870398,  908640,  948376,  989740, 1032874,

  104.     1077948, 1125150, 1174700, 1226850, 1281900, 1340196, 1402156, 1468282,

  105.     1539182, 1615610, 1698514, 1789098, 1888944, 2000168, 2125700, 2269750,

  106.     2438670, 2642660, 2899462, 3243240, 3746078, 4535138, 5664098, 7102424,

  107.     8897462,

  108. };

  109. static const int32_t invert_quantize_dither_factors_LF[65] = {

  110.        9948,   9948,   9962,   9988,  10026,  10078,  10142,  10218,

  111.       10306,  10408,  10520,  10646,  10784,  10934,  11098,  11274,

  112.       11462,  11664,  11880,  12112,  12358,  12618,  12898,  13194,

  113.       13510,  13844,  14202,  14582,  14988,  15422,  15884,  16380,

  114.       16912,  17484,  18098,  18762,  19480,  20258,  21106,  22030,

  115.       23044,  24158,  25390,  26760,  28290,  30008,  31954,  34172,

  116.       36728,  39700,  43202,  47382,  52462,  58762,  66770,  77280,

  117.       91642, 112348, 144452, 199326, 303512, 485546, 643414, 794914,

  118.     1000124,

  119. };

  120. static const int32_t quantize_dither_factors_LF[65] = {

  121.         0,     4,     7,    10,    13,    16,    19,    22,

  122.        26,    28,    32,    35,    38,    41,    44,    47,

  123.        51,    54,    58,    62,    65,    70,    74,    79,

  124.        84,    90,    95,   102,   109,   116,   124,   133,

  125.       143,   154,   166,   180,   195,   212,   231,   254,

  126.       279,   308,   343,   383,   430,   487,   555,   639,

  127.       743,   876,  1045,  1270,  1575,  2002,  2628,  3591,

  128.      5177,  8026, 13719, 26047, 45509, 39467, 37875, 51303,

  129.         0,

  130. };

  131. static const int16_t quantize_factor_select_offset_LF[65] = {

  132.       0, -21, -19, -17, -15, -12, -10,  -8,

  133.      -6,  -4,  -1,   1,   3,   6,   8,  10,

  134.      13,  15,  18,  20,  23,  26,  29,  31,

  135.      34,  37,  40,  43,  47,  50,  53,  57,

  136.      60,  64,  68,  72,  76,  80,  85,  89,

  137.      94,  99, 105, 110, 116, 123, 129, 136,

  138.     144, 152, 161, 171, 182, 194, 207, 223,

  139.     241, 263, 291, 328, 382, 467, 522, 522,

  140.     522,

  141. };

  142. 

  143. 

  144. static const int32_t quantize_intervals_MLF[9] = {

  145.     -89806, 89806, 278502, 494338, 759442, 1113112, 1652322, 2720256, 5190186,

  146. };

  147. static const int32_t invert_quantize_dither_factors_MLF[9] = {

  148.     89806, 89806, 98890, 116946, 148158, 205512, 333698, 734236, 1735696,

  149. };

  150. static const int32_t quantize_dither_factors_MLF[9] = {

  151.     0, 2271, 4514, 7803, 14339, 32047, 100135, 250365, 0,

  152. };

  153. static const int16_t quantize_factor_select_offset_MLF[9] = {

  154.     0, -14, 6, 29, 58, 96, 154, 270, 521,

  155. };

  156. 

  157. 

  158. static const int32_t quantize_intervals_MHF[3] = {

  159.     -194080, 194080, 890562,

  160. };

  161. static const int32_t invert_quantize_dither_factors_MHF[3] = {

  162.     194080, 194080, 502402,

  163. };

  164. static const int32_t quantize_dither_factors_MHF[3] = {

  165.     0, 77081, 0,

  166. };

  167. static const int16_t quantize_factor_select_offset_MHF[3] = {

  168.     0, -33, 136,

  169. };

  170. 

  171. 

  172. static const int32_t quantize_intervals_HF[5] = {

  173.     -163006, 163006, 542708, 1120554, 2669238,

  174. };

  175. static const int32_t invert_quantize_dither_factors_HF[5] = {

  176.     163006, 163006, 216698, 361148, 1187538,

  177. };

  178. static const int32_t quantize_dither_factors_HF[5] = {

  179.     0, 13423, 36113, 206598, 0,

  180. };

  181. static const int16_t quantize_factor_select_offset_HF[5] = {

  182.     0, -8, 33, 95, 262,

  183. };

  184. 

  185. typedef const struct {

  186.     const int32_t *quantize_intervals;

  187.     const int32_t *invert_quantize_dither_factors;

  188.     const int32_t *quantize_dither_factors;

  189.     const int16_t *quantize_factor_select_offset;

  190.     int tables_size;

  191.     int32_t factor_max;

  192.     int32_t prediction_order;

  193. } ConstTables;

  194. 

  195. static ConstTables tables[NB_SUBBANDS] = {

  196.     [LF]  = { quantize_intervals_LF,

  197.               invert_quantize_dither_factors_LF,

  198.               quantize_dither_factors_LF,

  199.               quantize_factor_select_offset_LF,

  200.               FF_ARRAY_ELEMS(quantize_intervals_LF),

  201.               0x11FF, 24 },

  202.     [MLF] = { quantize_intervals_MLF,

  203.               invert_quantize_dither_factors_MLF,

  204.               quantize_dither_factors_MLF,

  205.               quantize_factor_select_offset_MLF,

  206.               FF_ARRAY_ELEMS(quantize_intervals_MLF),

  207.               0x14FF, 12 },

  208.     [MHF] = { quantize_intervals_MHF,

  209.               invert_quantize_dither_factors_MHF,

  210.               quantize_dither_factors_MHF,

  211.               quantize_factor_select_offset_MHF,

  212.               FF_ARRAY_ELEMS(quantize_intervals_MHF),

  213.               0x16FF, 6 },

  214.     [HF]  = { quantize_intervals_HF,

  215.               invert_quantize_dither_factors_HF,

  216.               quantize_dither_factors_HF,

  217.               quantize_factor_select_offset_HF,

  218.               FF_ARRAY_ELEMS(quantize_intervals_HF),

  219.               0x15FF, 12 },

  220. };

  221. 

  222. static const int16_t quantization_factors[32] = {

  223.     2048, 2093, 2139, 2186, 2233, 2282, 2332, 2383,

  224.     2435, 2489, 2543, 2599, 2656, 2714, 2774, 2834,

  225.     2896, 2960, 3025, 3091, 3158, 3228, 3298, 3371,

  226.     3444, 3520, 3597, 3676, 3756, 3838, 3922, 4008,

  227. };

  228. 

  229. 

  230. /* Rounded right shift with optionnal clipping */

  231. #define RSHIFT_SIZE(size)                                                     \

  232. av_always_inline                                                              \

  233. static int##size##_t rshift##size(int##size##_t value, int shift)             \

  234. {                                                                             \

  235.     int##size##_t rounding = (int##size##_t)1 << (shift - 1);                 \

  236.     int##size##_t mask = ((int##size##_t)1 << (shift + 1)) - 1;               \

  237.     return ((value + rounding) >> shift) - ((value & mask) == rounding);      \

  238. }                                                                             \

  239. av_always_inline                                                              \

  240. static int##size##_t rshift##size##_clip24(int##size##_t value, int shift)    \

  241. {                                                                             \

  242.     return av_clip_intp2(rshift##size(value, shift), 23);                     \

  243. }

  244. RSHIFT_SIZE(32)

  245. RSHIFT_SIZE(64)

  246. 

  247. 

  248. av_always_inline

  249. static void aptx_update_codeword_history(Channel *channel)

  250. {

  251.     int32_t cw = ((channel->quantize[0].quantized_sample & 3) << 0) +

  252.                  ((channel->quantize[1].quantized_sample & 2) << 1) +

  253.                  ((channel->quantize[2].quantized_sample & 1) << 3);

  254.     channel->codeword_history = (cw << 8) + (channel->codeword_history << 4);

  255. }

  256. 

  257. static void aptx_generate_dither(Channel *channel)

  258. {

  259.     int subband;

  260.     int64_t m;

  261.     int32_t d;

  262. 

  263.     aptx_update_codeword_history(channel);

  264. 

  265.     m = (int64_t)5184443 * (channel->codeword_history >> 7);

  266.     d = (m << 2) + (m >> 22);

  267.     for (subband = 0; subband < NB_SUBBANDS; subband++)

  268.         channel->dither[subband] = d << (23 - 5*subband);

  269.     channel->dither_parity = (d >> 25) & 1;

  270. }

  271. 

  272. /*

  273.  * Convolution filter coefficients for the outer QMF of the QMF tree.

  274.  * The 2 sets are a mirror of each other.

  275.  */

  276. static const int32_t aptx_qmf_outer_coeffs[NB_FILTERS][FILTER_TAPS] = {

  277.     {

  278.         730, -413, -9611, 43626, -121026, 269973, -585547, 2801966,

  279.         697128, -160481, 27611, 8478, -10043, 3511, 688, -897,

  280.     },

  281.     {

  282.         -897, 688, 3511, -10043, 8478, 27611, -160481, 697128,

  283.         2801966, -585547, 269973, -121026, 43626, -9611, -413, 730,

  284.     },

  285. };

  286. 

  287. /*

  288.  * Convolution filter coefficients for the inner QMF of the QMF tree.

  289.  * The 2 sets are a mirror of each other.

  290.  */

  291. static const int32_t aptx_qmf_inner_coeffs[NB_FILTERS][FILTER_TAPS] = {

  292.     {

  293.        1033, -584, -13592, 61697, -171156, 381799, -828088, 3962579,

  294.        985888, -226954, 39048, 11990, -14203, 4966, 973, -1268,

  295.     },

  296.     {

  297.       -1268, 973, 4966, -14203, 11990, 39048, -226954, 985888,

  298.       3962579, -828088, 381799, -171156, 61697, -13592, -584, 1033,

  299.     },

  300. };

  301. 

  302. /*

  303.  * Push one sample into a circular signal buffer.

  304.  */

  305. av_always_inline

  306. static void aptx_qmf_filter_signal_push(FilterSignal *signal, int32_t sample)

  307. {

  308.     signal->buffer[signal->pos            ] = sample;

  309.     signal->buffer[signal->pos+FILTER_TAPS] = sample;

  310.     signal->pos = (signal->pos + 1) & (FILTER_TAPS - 1);

  311. }

  312. 

  313. /*

  314.  * Compute the convolution of the signal with the coefficients, and reduce

  315.  * to 24 bits by applying the specified right shifting.

  316.  */

  317. av_always_inline

  318. static int32_t aptx_qmf_convolution(FilterSignal *signal,

  319.                                     const int32_t coeffs[FILTER_TAPS],

  320.                                     int shift)

  321. {

  322.     int32_t *sig = &signal->buffer[signal->pos];

  323.     int64_t e = 0;

  324.     int i;

  325. 

  326.     for (i = 0; i < FILTER_TAPS; i++)

  327.         e += MUL64(sig[i], coeffs[i]);

  328. 

  329.     return rshift64_clip24(e, shift);

  330. }

  331. 

  332. /*

  333.  * Half-band QMF analysis filter realized with a polyphase FIR filter.

  334.  * Split into 2 subbands and downsample by 2.

  335.  * So for each pair of samples that goes in, one sample goes out,

  336.  * split into 2 separate subbands.

  337.  */

  338. av_always_inline

  339. static void aptx_qmf_polyphase_analysis(FilterSignal signal[NB_FILTERS],

  340.                                         const int32_t coeffs[NB_FILTERS][FILTER_TAPS],

  341.                                         int shift,

  342.                                         int32_t samples[NB_FILTERS],

  343.                                         int32_t *low_subband_output,

  344.                                         int32_t *high_subband_output)

  345. {

  346.     int32_t subbands[NB_FILTERS];

  347.     int i;

  348. 

  349.     for (i = 0; i < NB_FILTERS; i++) {

  350.         aptx_qmf_filter_signal_push(&signal[i], samples[NB_FILTERS-1-i]);

  351.         subbands[i] = aptx_qmf_convolution(&signal[i], coeffs[i], shift);

  352.     }

  353. 

  354.     *low_subband_output  = av_clip_intp2(subbands[0] + subbands[1], 23);

  355.     *high_subband_output = av_clip_intp2(subbands[0] - subbands[1], 23);

  356. }

  357. 

  358. /*

  359.  * Two stage QMF analysis tree.

  360.  * Split 4 input samples into 4 subbands and downsample by 4.

  361.  * So for each group of 4 samples that goes in, one sample goes out,

  362.  * split into 4 separate subbands.

  363.  */

  364. static void aptx_qmf_tree_analysis(QMFAnalysis *qmf,

  365.                                    int32_t samples[4],

  366.                                    int32_t subband_samples[4])

  367. {

  368.     int32_t intermediate_samples[4];

  369.     int i;

  370. 

  371.     /* Split 4 input samples into 2 intermediate subbands downsampled to 2 samples */

  372.     for (i = 0; i < 2; i++)

  373.         aptx_qmf_polyphase_analysis(qmf->outer_filter_signal,

  374.                                     aptx_qmf_outer_coeffs, 23,

  375.                                     &samples[2*i],

  376.                                     &intermediate_samples[0+i],

  377.                                     &intermediate_samples[2+i]);

  378. 

  379.     /* Split 2 intermediate subband samples into 4 final subbands downsampled to 1 sample */

  380.     for (i = 0; i < 2; i++)

  381.         aptx_qmf_polyphase_analysis(qmf->inner_filter_signal[i],

  382.                                     aptx_qmf_inner_coeffs, 23,

  383.                                     &intermediate_samples[2*i],

  384.                                     &subband_samples[2*i+0],

  385.                                     &subband_samples[2*i+1]);

  386. }

  387. 

  388. /*

  389.  * Half-band QMF synthesis filter realized with a polyphase FIR filter.

  390.  * Join 2 subbands and upsample by 2.

  391.  * So for each 2 subbands sample that goes in, a pair of samples goes out.

  392.  */

  393. av_always_inline

  394. static void aptx_qmf_polyphase_synthesis(FilterSignal signal[NB_FILTERS],

  395.                                          const int32_t coeffs[NB_FILTERS][FILTER_TAPS],

  396.                                          int shift,

  397.                                          int32_t low_subband_input,

  398.                                          int32_t high_subband_input,

  399.                                          int32_t samples[NB_FILTERS])

  400. {

  401.     int32_t subbands[NB_FILTERS];

  402.     int i;

  403. 

  404.     subbands[0] = low_subband_input + high_subband_input;

  405.     subbands[1] = low_subband_input - high_subband_input;

  406. 

  407.     for (i = 0; i < NB_FILTERS; i++) {

  408.         aptx_qmf_filter_signal_push(&signal[i], subbands[1-i]);

  409.         samples[i] = aptx_qmf_convolution(&signal[i], coeffs[i], shift);

  410.     }

  411. }

  412. 

  413. /*

  414.  * Two stage QMF synthesis tree.

  415.  * Join 4 subbands and upsample by 4.

  416.  * So for each 4 subbands sample that goes in, a group of 4 samples goes out.

  417.  */

  418. static void aptx_qmf_tree_synthesis(QMFAnalysis *qmf,

  419.                                     int32_t subband_samples[4],

  420.                                     int32_t samples[4])

  421. {

  422.     int32_t intermediate_samples[4];

  423.     int i;

  424. 

  425.     /* Join 4 subbands into 2 intermediate subbands upsampled to 2 samples. */

  426.     for (i = 0; i < 2; i++)

  427.         aptx_qmf_polyphase_synthesis(qmf->inner_filter_signal[i],

  428.                                      aptx_qmf_inner_coeffs, 22,

  429.                                      subband_samples[2*i+0],

  430.                                      subband_samples[2*i+1],

  431.                                      &intermediate_samples[2*i]);

  432. 

  433.     /* Join 2 samples from intermediate subbands upsampled to 4 samples. */

  434.     for (i = 0; i < 2; i++)

  435.         aptx_qmf_polyphase_synthesis(qmf->outer_filter_signal,

  436.                                      aptx_qmf_outer_coeffs, 21,

  437.                                      intermediate_samples[0+i],

  438.                                      intermediate_samples[2+i],

  439.                                      &samples[2*i]);

  440. }

  441. 

  442. 

  443. av_always_inline

  444. static int32_t aptx_bin_search(int32_t value, int32_t factor,

  445.                                const int32_t *intervals, int32_t nb_intervals)

  446. {

  447.     int32_t idx = 0;

  448.     int i;

  449. 

  450.     for (i = nb_intervals >> 1; i > 0; i >>= 1)

  451.         if (MUL64(factor, intervals[idx + i]) <= ((int64_t)value << 24))

  452.             idx += i;

  453. 

  454.     return idx;

  455. }

  456. 

  457. static void aptx_quantize_difference(Quantize *quantize,

  458.                                      int32_t sample_difference,

  459.                                      int32_t dither,

  460.                                      int32_t quantization_factor,

  461.                                      ConstTables *tables)

  462. {

  463.     const int32_t *intervals = tables->quantize_intervals;

  464.     int32_t quantized_sample, dithered_sample, parity_change;

  465.     int32_t d, mean, interval, inv;

  466.     int64_t error;

  467. 

  468.     quantized_sample = aptx_bin_search(FFABS(sample_difference) >> 4,

  469.                                        quantization_factor,

  470.                                        intervals, tables->tables_size);

  471. 

  472.     d = rshift32_clip24(MULH(dither, dither), 7) - (1 << 23);

  473.     d = rshift64(MUL64(d, tables->quantize_dither_factors[quantized_sample]), 23);

  474. 

  475.     intervals += quantized_sample;

  476.     mean = (intervals[1] + intervals[0]) / 2;

  477.     interval = (intervals[1] - intervals[0]) * (-(sample_difference < 0) | 1);

  478. 

  479.     dithered_sample = rshift64_clip24(MUL64(dither, interval) + ((int64_t)(mean + d) << 32), 32);

  480.     error = ((int64_t)FFABS(sample_difference) << 20) - MUL64(dithered_sample, quantization_factor);

  481.     quantize->error = FFABS(rshift64(error, 23));

  482. 

  483.     parity_change = quantized_sample;

  484.     if (error < 0)

  485.         quantized_sample--;

  486.     else

  487.         parity_change--;

  488. 

  489.     inv = -(sample_difference < 0);

  490.     quantize->quantized_sample               = quantized_sample ^ inv;

  491.     quantize->quantized_sample_parity_change = parity_change    ^ inv;

  492. }

  493. 

  494. static void aptx_encode_channel(Channel *channel, int32_t samples[4])

  495. {

  496.     int32_t subband_samples[4];

  497.     int subband;

  498.     aptx_qmf_tree_analysis(&channel->qmf, samples, subband_samples);

  499.     aptx_generate_dither(channel);

  500.     for (subband = 0; subband < NB_SUBBANDS; subband++) {

  501.         int32_t diff = av_clip_intp2(subband_samples[subband] - channel->prediction[subband].predicted_sample, 23);

  502.         aptx_quantize_difference(&channel->quantize[subband], diff,

  503.                                  channel->dither[subband],

  504.                                  channel->invert_quantize[subband].quantization_factor,

  505.                                  &tables[subband]);

  506.     }

  507. }

  508. 

  509. static void aptx_decode_channel(Channel *channel, int32_t samples[4])

  510. {

  511.     int32_t subband_samples[4];

  512.     int subband;

  513.     for (subband = 0; subband < NB_SUBBANDS; subband++)

  514.         subband_samples[subband] = channel->prediction[subband].previous_reconstructed_sample;

  515.     aptx_qmf_tree_synthesis(&channel->qmf, subband_samples, samples);

  516. }

  517. 

  518. 

  519. static void aptx_invert_quantization(InvertQuantize *invert_quantize,

  520.                                      int32_t quantized_sample, int32_t dither,

  521.                                      ConstTables *tables)

  522. {

  523.     int32_t qr, idx, shift, factor_select;

  524. 

  525.     idx = (quantized_sample ^ -(quantized_sample < 0)) + 1;

  526.     qr = tables->quantize_intervals[idx] / 2;

  527.     if (quantized_sample < 0)

  528.         qr = -qr;

  529. 

  530.     qr = rshift64_clip24(((int64_t)qr<<32) + MUL64(dither, tables->invert_quantize_dither_factors[idx]), 32);

  531.     invert_quantize->reconstructed_difference = MUL64(invert_quantize->quantization_factor, qr) >> 19;

  532. 

  533.     /* update factor_select */

  534.     factor_select = 32620 * invert_quantize->factor_select;

  535.     factor_select = rshift32(factor_select + (tables->quantize_factor_select_offset[idx] << 15), 15);

  536.     invert_quantize->factor_select = av_clip(factor_select, 0, tables->factor_max);

  537. 

  538.     /* update quantization factor */

  539.     idx = (invert_quantize->factor_select & 0xFF) >> 3;

  540.     shift = (tables->factor_max - invert_quantize->factor_select) >> 8;

  541.     invert_quantize->quantization_factor = (quantization_factors[idx] << 11) >> shift;

  542. }

  543. 

  544. static int32_t *aptx_reconstructed_differences_update(Prediction *prediction,

  545.                                                       int32_t reconstructed_difference,

  546.                                                       int order)

  547. {

  548.     int32_t *rd1 = prediction->reconstructed_differences, *rd2 = rd1 + order;

  549.     int p = prediction->pos;

  550. 

  551.     rd1[p] = rd2[p];

  552.     prediction->pos = p = (p + 1) % order;

  553.     rd2[p] = reconstructed_difference;

  554.     return &rd2[p];

  555. }

  556. 

  557. static void aptx_prediction_filtering(Prediction *prediction,

  558.                                       int32_t reconstructed_difference,

  559.                                       int order)

  560. {

  561.     int32_t reconstructed_sample, predictor, srd0;

  562.     int32_t *reconstructed_differences;

  563.     int64_t predicted_difference = 0;

  564.     int i;

  565. 

  566.     reconstructed_sample = av_clip_intp2(reconstructed_difference + prediction->predicted_sample, 23);

  567.     predictor = av_clip_intp2((MUL64(prediction->s_weight[0], prediction->previous_reconstructed_sample)

  568.                              + MUL64(prediction->s_weight[1], reconstructed_sample)) >> 22, 23);

  569.     prediction->previous_reconstructed_sample = reconstructed_sample;

  570. 

  571.     reconstructed_differences = aptx_reconstructed_differences_update(prediction, reconstructed_difference, order);

  572.     srd0 = FFDIFFSIGN(reconstructed_difference, 0) << 23;

  573.     for (i = 0; i < order; i++) {

  574.         int32_t srd = FF_SIGNBIT(reconstructed_differences[-i-1]) | 1;

  575.         prediction->d_weight[i] -= rshift32(prediction->d_weight[i] - srd*srd0, 8);

  576.         predicted_difference += MUL64(reconstructed_differences[-i], prediction->d_weight[i]);

  577.     }

  578. 

  579.     prediction->predicted_difference = av_clip_intp2(predicted_difference >> 22, 23);

  580.     prediction->predicted_sample = av_clip_intp2(predictor + prediction->predicted_difference, 23);

  581. }

  582. 

  583. static void aptx_process_subband(InvertQuantize *invert_quantize,

  584.                                  Prediction *prediction,

  585.                                  int32_t quantized_sample, int32_t dither,

  586.                                  ConstTables *tables)

  587. {

  588.     int32_t sign, same_sign[2], weight[2], sw1, range;

  589. 

  590.     aptx_invert_quantization(invert_quantize, quantized_sample, dither, tables);

  591. 

  592.     sign = FFDIFFSIGN(invert_quantize->reconstructed_difference,

  593.                       -prediction->predicted_difference);

  594.     same_sign[0] = sign * prediction->prev_sign[0];

  595.     same_sign[1] = sign * prediction->prev_sign[1];

  596.     prediction->prev_sign[0] = prediction->prev_sign[1];

  597.     prediction->prev_sign[1] = sign | 1;

  598. 

  599.     range = 0x100000;

  600.     sw1 = rshift32(-same_sign[1] * prediction->s_weight[1], 1);

  601.     sw1 = (av_clip(sw1, -range, range) & ~0xF) << 4;

  602. 

  603.     range = 0x300000;

  604.     weight[0] = 254 * prediction->s_weight[0] + 0x800000*same_sign[0] + sw1;

  605.     prediction->s_weight[0] = av_clip(rshift32(weight[0], 8), -range, range);

  606. 

  607.     range = 0x3C0000 - prediction->s_weight[0];

  608.     weight[1] = 255 * prediction->s_weight[1] + 0xC00000*same_sign[1];

  609.     prediction->s_weight[1] = av_clip(rshift32(weight[1], 8), -range, range);

  610. 

  611.     aptx_prediction_filtering(prediction,

  612.                               invert_quantize->reconstructed_difference,

  613.                               tables->prediction_order);

  614. }

  615. 

  616. static void aptx_invert_quantize_and_prediction(Channel *channel)

  617. {

  618.     int subband;

  619.     for (subband = 0; subband < NB_SUBBANDS; subband++)

  620.         aptx_process_subband(&channel->invert_quantize[subband],

  621.                              &channel->prediction[subband],

  622.                              channel->quantize[subband].quantized_sample,

  623.                              channel->dither[subband],

  624.                              &tables[subband]);

  625. }

  626. 

  627. static int32_t aptx_quantized_parity(Channel *channel)

  628. {

  629.     int32_t parity = channel->dither_parity;

  630.     int subband;

  631. 

  632.     for (subband = 0; subband < NB_SUBBANDS; subband++)

  633.         parity ^= channel->quantize[subband].quantized_sample;

  634. 

  635.     return parity & 1;

  636. }

  637. 

  638. /* For each sample, ensure that the parity of all subbands of all channels

  639.  * is 0 except once every 8 samples where the parity is forced to 1. */

  640. static int aptx_check_parity(Channel channels[NB_CHANNELS], int32_t *idx)

  641. {

  642.     int32_t parity = aptx_quantized_parity(&channels[LEFT])

  643.                    ^ aptx_quantized_parity(&channels[RIGHT]);

  644. 

  645.     int eighth = *idx == 7;

  646.     *idx = (*idx + 1) & 7;

  647. 

  648.     return parity ^ eighth;

  649. }

  650. 

  651. static void aptx_insert_sync(Channel channels[NB_CHANNELS], int32_t *idx)

  652. {

  653.     if (aptx_check_parity(channels, idx)) {

  654.         int i;

  655.         Channel *c;

  656.         static const int map[] = { 1, 2, 0, 3 };

  657.         Quantize *min = &channels[NB_CHANNELS-1].quantize[map[0]];

  658.         for (c = &channels[NB_CHANNELS-1]; c >= channels; c--)

  659.             for (i = 0; i < NB_SUBBANDS; i++)

  660.                 if (c->quantize[map[i]].error < min->error)

  661.                     min = &c->quantize[map[i]];

  662. 

  663.         /* Forcing the desired parity is done by offsetting by 1 the quantized

  664.          * sample from the subband featuring the smallest quantization error. */

  665.         min->quantized_sample = min->quantized_sample_parity_change;

  666.     }

  667. }

  668. 

  669. static uint16_t aptx_pack_codeword(Channel *channel)

  670. {

  671.     int32_t parity = aptx_quantized_parity(channel);

  672.     return (((channel->quantize[3].quantized_sample & 0x06) | parity) << 13)

  673.          | (((channel->quantize[2].quantized_sample & 0x03)         ) << 11)

  674.          | (((channel->quantize[1].quantized_sample & 0x0F)         ) <<  7)

  675.          | (((channel->quantize[0].quantized_sample & 0x7F)         ) <<  0);

  676. }

  677. 

  678. static void aptx_unpack_codeword(Channel *channel, uint16_t codeword)

  679. {

  680.     channel->quantize[0].quantized_sample = sign_extend(codeword >>  0, 7);

  681.     channel->quantize[1].quantized_sample = sign_extend(codeword >>  7, 4);

  682.     channel->quantize[2].quantized_sample = sign_extend(codeword >> 11, 2);

  683.     channel->quantize[3].quantized_sample = sign_extend(codeword >> 13, 3);

  684.     channel->quantize[3].quantized_sample = (channel->quantize[3].quantized_sample & ~1)

  685.                                           | aptx_quantized_parity(channel);

  686. }

  687. 

  688. static void aptx_encode_samples(AptXContext *ctx,

  689.                                 int32_t samples[NB_CHANNELS][4],

  690.                                 uint8_t output[2*NB_CHANNELS])

  691. {

  692.     int channel;

  693.     for (channel = 0; channel < NB_CHANNELS; channel++)

  694.         aptx_encode_channel(&ctx->channels[channel], samples[channel]);

  695. 

  696.     aptx_insert_sync(ctx->channels, &ctx->sync_idx);

  697. 

  698.     for (channel = 0; channel < NB_CHANNELS; channel++) {

  699.         aptx_invert_quantize_and_prediction(&ctx->channels[channel]);

  700.         AV_WB16(output + 2*channel, aptx_pack_codeword(&ctx->channels[channel]));

  701.     }

  702. }

  703. 

  704. static int aptx_decode_samples(AptXContext *ctx,

  705.                                 const uint8_t input[2*NB_CHANNELS],

  706.                                 int32_t samples[NB_CHANNELS][4])

  707. {

  708.     int channel, ret;

  709. 

  710.     for (channel = 0; channel < NB_CHANNELS; channel++) {

  711.         uint16_t codeword;

  712.         aptx_generate_dither(&ctx->channels[channel]);

  713. 

  714.         codeword = AV_RB16(input + 2*channel);

  715.         aptx_unpack_codeword(&ctx->channels[channel], codeword);

  716.         aptx_invert_quantize_and_prediction(&ctx->channels[channel]);

  717.     }

  718. 

  719.     ret = aptx_check_parity(ctx->channels, &ctx->sync_idx);

  720. 

  721.     for (channel = 0; channel < NB_CHANNELS; channel++)

  722.         aptx_decode_channel(&ctx->channels[channel], samples[channel]);

  723. 

  724.     return ret;

  725. }

  726. 

  727. 

  728. static av_cold int aptx_init(AVCodecContext *avctx)

  729. {

  730.     AptXContext *s = avctx->priv_data;

  731.     int chan, subband;

  732. 

  733.     if (avctx->frame_size == 0)

  734.         avctx->frame_size = 1024;

  735. 

  736.     if (avctx->frame_size & 3) {

  737.         av_log(avctx, AV_LOG_ERROR, "Frame size must be a multiple of 4 samples\n");

  738.         return AVERROR(EINVAL);

  739.     }

  740. 

  741.     for (chan = 0; chan < NB_CHANNELS; chan++) {

  742.         Channel *channel = &s->channels[chan];

  743.         for (subband = 0; subband < NB_SUBBANDS; subband++) {

  744.             Prediction *prediction = &channel->prediction[subband];

  745.             prediction->prev_sign[0] = 1;

  746.             prediction->prev_sign[1] = 1;

  747.         }

  748.     }

  749. 

  750.     ff_af_queue_init(avctx, &s->afq);

  751.     return 0;

  752. }

  753. 

  754. static int aptx_decode_frame(AVCodecContext *avctx, void *data,

  755.                              int *got_frame_ptr, AVPacket *avpkt)

  756. {

  757.     AptXContext *s = avctx->priv_data;

  758.     AVFrame *frame = data;

  759.     int pos, channel, sample, ret;

  760. 

  761.     if (avpkt->size < 4) {

  762.         av_log(avctx, AV_LOG_ERROR, "Packet is too small\n");

  763.         return AVERROR_INVALIDDATA;

  764.     }

  765. 

  766.     /* get output buffer */

  767.     frame->channels = NB_CHANNELS;

  768.     frame->format = AV_SAMPLE_FMT_S32P;

  769.     frame->nb_samples = avpkt->size & ~3;

  770.     if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)

  771.         return ret;

  772. 

  773.     for (pos = 0; pos < frame->nb_samples; pos += 4) {

  774.         int32_t samples[NB_CHANNELS][4];

  775. 

  776.         if (aptx_decode_samples(s, &avpkt->data[pos], samples)) {

  777.             av_log(avctx, AV_LOG_ERROR, "Synchronization error\n");

  778.             return AVERROR_INVALIDDATA;

  779.         }

  780. 

  781.         for (channel = 0; channel < NB_CHANNELS; channel++)

  782.             for (sample = 0; sample < 4; sample++)

  783.                 AV_WN32A(&frame->data[channel][4*(sample+pos)],

  784.                          samples[channel][sample] << 8);

  785.     }

  786. 

  787.     *got_frame_ptr = 1;

  788.     return frame->nb_samples;

  789. }

  790. 

  791. static int aptx_encode_frame(AVCodecContext *avctx, AVPacket *avpkt,

  792.                              const AVFrame *frame, int *got_packet_ptr)

  793. {

  794.     AptXContext *s = avctx->priv_data;

  795.     int pos, channel, sample, ret;

  796. 

  797.     if ((ret = ff_af_queue_add(&s->afq, frame)) < 0)

  798.         return ret;

  799. 

  800.     if ((ret = ff_alloc_packet2(avctx, avpkt, frame->nb_samples, 0)) < 0)

  801.         return ret;

  802. 

  803.     for (pos = 0; pos < frame->nb_samples; pos += 4) {

  804.         int32_t samples[NB_CHANNELS][4];

  805. 

  806.         for (channel = 0; channel < NB_CHANNELS; channel++)

  807.             for (sample = 0; sample < 4; sample++)

  808.                 samples[channel][sample] = (int32_t)AV_RN32A(&frame->data[channel][4*(sample+pos)]) >> 8;

  809. 

  810.         aptx_encode_samples(s, samples, avpkt->data + pos);

  811.     }

  812. 

  813.     ff_af_queue_remove(&s->afq, frame->nb_samples, &avpkt->pts, &avpkt->duration);

  814.     *got_packet_ptr = 1;

  815.     return 0;

  816. }

  817. 

  818. static av_cold int aptx_close(AVCodecContext *avctx)

  819. {

  820.     AptXContext *s = avctx->priv_data;

  821.     ff_af_queue_close(&s->afq);

  822.     return 0;

  823. }

  824. 

  825. 

  826. #if CONFIG_APTX_DECODER

  827. AVCodec ff_aptx_decoder = {

  828.     .name                  = "aptx",

  829.     .long_name             = NULL_IF_CONFIG_SMALL("aptX (Audio Processing Technology for Bluetooth)"),

  830.     .type                  = AVMEDIA_TYPE_AUDIO,

  831.     .id                    = AV_CODEC_ID_APTX,

  832.     .priv_data_size        = sizeof(AptXContext),

  833.     .init                  = aptx_init,

  834.     .decode                = aptx_decode_frame,

  835.     .close                 = aptx_close,

  836.     .capabilities          = AV_CODEC_CAP_DR1,

  837.     .caps_internal         = FF_CODEC_CAP_INIT_THREADSAFE,

  838.     .channel_layouts       = (const uint64_t[]) { AV_CH_LAYOUT_STEREO, 0},

  839.     .sample_fmts           = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_S32P,

  840.                                                              AV_SAMPLE_FMT_NONE },

  841. };

  842. #endif

  843. 

  844. #if CONFIG_APTX_ENCODER

  845. AVCodec ff_aptx_encoder = {

  846.     .name                  = "aptx",

  847.     .long_name             = NULL_IF_CONFIG_SMALL("aptX (Audio Processing Technology for Bluetooth)"),

  848.     .type                  = AVMEDIA_TYPE_AUDIO,

  849.     .id                    = AV_CODEC_ID_APTX,

  850.     .priv_data_size        = sizeof(AptXContext),

  851.     .init                  = aptx_init,

  852.     .encode2               = aptx_encode_frame,

  853.     .close                 = aptx_close,

  854.     .capabilities          = AV_CODEC_CAP_SMALL_LAST_FRAME,

  855.     .caps_internal         = FF_CODEC_CAP_INIT_THREADSAFE,

  856.     .channel_layouts       = (const uint64_t[]) { AV_CH_LAYOUT_STEREO, 0},

  857.     .sample_fmts           = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_S32P,

  858.                                                              AV_SAMPLE_FMT_NONE },

  859.     .supported_samplerates = (const int[]) {8000, 16000, 24000, 32000, 44100, 48000, 0},

  860. };

  861. #endif