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FFmpeg/libavcodec/aacsbr.c

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  1. /*

  2.  * AAC Spectral Band Replication decoding functions

  3.  * Copyright (c) 2008-2009 Robert Swain ( rob opendot cl )

  4.  * Copyright (c) 2009-2010 Alex Converse <alex.converse@gmail.com>

  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. /**

  24.  * @file

  25.  * AAC Spectral Band Replication decoding functions

  26.  * @author Robert Swain ( rob opendot cl )

  27.  */

  28. 

  29. #include "aac.h"

  30. #include "sbr.h"

  31. #include "aacsbr.h"

  32. #include "aacsbrdata.h"

  33. #include "fft.h"

  34. #include "aacps.h"

  35. #include "libavutil/libm.h"

  36. #include "libavutil/avassert.h"

  37. 

  38. #include <stdint.h>

  39. #include <float.h>

  40. #include <math.h>

  41. 

  42. #define ENVELOPE_ADJUSTMENT_OFFSET 2

  43. #define NOISE_FLOOR_OFFSET 6.0f

  44. 

  45. /**

  46.  * SBR VLC tables

  47.  */

  48. enum {

  49.     T_HUFFMAN_ENV_1_5DB,

  50.     F_HUFFMAN_ENV_1_5DB,

  51.     T_HUFFMAN_ENV_BAL_1_5DB,

  52.     F_HUFFMAN_ENV_BAL_1_5DB,

  53.     T_HUFFMAN_ENV_3_0DB,

  54.     F_HUFFMAN_ENV_3_0DB,

  55.     T_HUFFMAN_ENV_BAL_3_0DB,

  56.     F_HUFFMAN_ENV_BAL_3_0DB,

  57.     T_HUFFMAN_NOISE_3_0DB,

  58.     T_HUFFMAN_NOISE_BAL_3_0DB,

  59. };

  60. 

  61. /**

  62.  * bs_frame_class - frame class of current SBR frame (14496-3 sp04 p98)

  63.  */

  64. enum {

  65.     FIXFIX,

  66.     FIXVAR,

  67.     VARFIX,

  68.     VARVAR,

  69. };

  70. 

  71. enum {

  72.     EXTENSION_ID_PS = 2,

  73. };

  74. 

  75. static VLC vlc_sbr[10];

  76. static const int8_t vlc_sbr_lav[10] =

  77.     { 60, 60, 24, 24, 31, 31, 12, 12, 31, 12 };

  78. static const DECLARE_ALIGNED(16, float, zero64)[64];

  79. 

  80. #define SBR_INIT_VLC_STATIC(num, size) \

  81.     INIT_VLC_STATIC(&vlc_sbr[num], 9, sbr_tmp[num].table_size / sbr_tmp[num].elem_size,     \

  82.                     sbr_tmp[num].sbr_bits ,                      1,                      1, \

  83.                     sbr_tmp[num].sbr_codes, sbr_tmp[num].elem_size, sbr_tmp[num].elem_size, \

  84.                     size)

  85. 

  86. #define SBR_VLC_ROW(name) \

  87.     { name ## _codes, name ## _bits, sizeof(name ## _codes), sizeof(name ## _codes[0]) }

  88. 

  89. av_cold void ff_aac_sbr_init(void)

  90. {

  91.     int n;

  92.     static const struct {

  93.         const void *sbr_codes, *sbr_bits;

  94.         const unsigned int table_size, elem_size;

  95.     } sbr_tmp[] = {

  96.         SBR_VLC_ROW(t_huffman_env_1_5dB),

  97.         SBR_VLC_ROW(f_huffman_env_1_5dB),

  98.         SBR_VLC_ROW(t_huffman_env_bal_1_5dB),

  99.         SBR_VLC_ROW(f_huffman_env_bal_1_5dB),

  100.         SBR_VLC_ROW(t_huffman_env_3_0dB),

  101.         SBR_VLC_ROW(f_huffman_env_3_0dB),

  102.         SBR_VLC_ROW(t_huffman_env_bal_3_0dB),

  103.         SBR_VLC_ROW(f_huffman_env_bal_3_0dB),

  104.         SBR_VLC_ROW(t_huffman_noise_3_0dB),

  105.         SBR_VLC_ROW(t_huffman_noise_bal_3_0dB),

  106.     };

  107. 

  108.     // SBR VLC table initialization

  109.     SBR_INIT_VLC_STATIC(0, 1098);

  110.     SBR_INIT_VLC_STATIC(1, 1092);

  111.     SBR_INIT_VLC_STATIC(2, 768);

  112.     SBR_INIT_VLC_STATIC(3, 1026);

  113.     SBR_INIT_VLC_STATIC(4, 1058);

  114.     SBR_INIT_VLC_STATIC(5, 1052);

  115.     SBR_INIT_VLC_STATIC(6, 544);

  116.     SBR_INIT_VLC_STATIC(7, 544);

  117.     SBR_INIT_VLC_STATIC(8, 592);

  118.     SBR_INIT_VLC_STATIC(9, 512);

  119. 

  120.     for (n = 1; n < 320; n++)

  121.         sbr_qmf_window_us[320 + n] = sbr_qmf_window_us[320 - n];

  122.     sbr_qmf_window_us[384] = -sbr_qmf_window_us[384];

  123.     sbr_qmf_window_us[512] = -sbr_qmf_window_us[512];

  124. 

  125.     for (n = 0; n < 320; n++)

  126.         sbr_qmf_window_ds[n] = sbr_qmf_window_us[2*n];

  127. 

  128.     ff_ps_init();

  129. }

  130. 

  131. av_cold void ff_aac_sbr_ctx_init(AACContext *ac, SpectralBandReplication *sbr)

  132. {

  133.     float mdct_scale;

  134.     if(sbr->mdct.mdct_bits)

  135.         return;

  136.     sbr->kx[0] = sbr->kx[1] = 32; //Typo in spec, kx' inits to 32

  137.     sbr->data[0].e_a[1] = sbr->data[1].e_a[1] = -1;

  138.     sbr->data[0].synthesis_filterbank_samples_offset = SBR_SYNTHESIS_BUF_SIZE - (1280 - 128);

  139.     sbr->data[1].synthesis_filterbank_samples_offset = SBR_SYNTHESIS_BUF_SIZE - (1280 - 128);

  140.     /* SBR requires samples to be scaled to +/-32768.0 to work correctly.

  141.      * mdct scale factors are adjusted to scale up from +/-1.0 at analysis

  142.      * and scale back down at synthesis. */

  143.     mdct_scale = ac->avctx->sample_fmt == AV_SAMPLE_FMT_FLT ? 32768.0f : 1.0f;

  144.     ff_mdct_init(&sbr->mdct,     7, 1, 1.0 / (64 * mdct_scale));

  145.     ff_mdct_init(&sbr->mdct_ana, 7, 1, -2.0 * mdct_scale);

  146.     ff_ps_ctx_init(&sbr->ps);

  147. }

  148. 

  149. av_cold void ff_aac_sbr_ctx_close(SpectralBandReplication *sbr)

  150. {

  151.     ff_mdct_end(&sbr->mdct);

  152.     ff_mdct_end(&sbr->mdct_ana);

  153. }

  154. 

  155. static int qsort_comparison_function_int16(const void *a, const void *b)

  156. {

  157.     return *(const int16_t *)a - *(const int16_t *)b;

  158. }

  159. 

  160. static inline int in_table_int16(const int16_t *table, int last_el, int16_t needle)

  161. {

  162.     int i;

  163.     for (i = 0; i <= last_el; i++)

  164.         if (table[i] == needle)

  165.             return 1;

  166.     return 0;

  167. }

  168. 

  169. /// Limiter Frequency Band Table (14496-3 sp04 p198)

  170. static void sbr_make_f_tablelim(SpectralBandReplication *sbr)

  171. {

  172.     int k;

  173.     if (sbr->bs_limiter_bands > 0) {

  174.         static const float bands_warped[3] = { 1.32715174233856803909f,   //2^(0.49/1.2)

  175.                                                1.18509277094158210129f,   //2^(0.49/2)

  176.                                                1.11987160404675912501f }; //2^(0.49/3)

  177.         const float lim_bands_per_octave_warped = bands_warped[sbr->bs_limiter_bands - 1];

  178.         int16_t patch_borders[7];

  179.         uint16_t *in = sbr->f_tablelim + 1, *out = sbr->f_tablelim;

  180. 

  181.         patch_borders[0] = sbr->kx[1];

  182.         for (k = 1; k <= sbr->num_patches; k++)

  183.             patch_borders[k] = patch_borders[k-1] + sbr->patch_num_subbands[k-1];

  184. 

  185.         memcpy(sbr->f_tablelim, sbr->f_tablelow,

  186.                (sbr->n[0] + 1) * sizeof(sbr->f_tablelow[0]));

  187.         if (sbr->num_patches > 1)

  188.             memcpy(sbr->f_tablelim + sbr->n[0] + 1, patch_borders + 1,

  189.                    (sbr->num_patches - 1) * sizeof(patch_borders[0]));

  190. 

  191.         qsort(sbr->f_tablelim, sbr->num_patches + sbr->n[0],

  192.               sizeof(sbr->f_tablelim[0]),

  193.               qsort_comparison_function_int16);

  194. 

  195.         sbr->n_lim = sbr->n[0] + sbr->num_patches - 1;

  196.         while (out < sbr->f_tablelim + sbr->n_lim) {

  197.             if (*in >= *out * lim_bands_per_octave_warped) {

  198.                 *++out = *in++;

  199.             } else if (*in == *out ||

  200.                 !in_table_int16(patch_borders, sbr->num_patches, *in)) {

  201.                 in++;

  202.                 sbr->n_lim--;

  203.             } else if (!in_table_int16(patch_borders, sbr->num_patches, *out)) {

  204.                 *out = *in++;

  205.                 sbr->n_lim--;

  206.             } else {

  207.                 *++out = *in++;

  208.             }

  209.         }

  210.     } else {

  211.         sbr->f_tablelim[0] = sbr->f_tablelow[0];

  212.         sbr->f_tablelim[1] = sbr->f_tablelow[sbr->n[0]];

  213.         sbr->n_lim = 1;

  214.     }

  215. }

  216. 

  217. static unsigned int read_sbr_header(SpectralBandReplication *sbr, GetBitContext *gb)

  218. {

  219.     unsigned int cnt = get_bits_count(gb);

  220.     uint8_t bs_header_extra_1;

  221.     uint8_t bs_header_extra_2;

  222.     int old_bs_limiter_bands = sbr->bs_limiter_bands;

  223.     SpectrumParameters old_spectrum_params;

  224. 

  225.     sbr->start = 1;

  226. 

  227.     // Save last spectrum parameters variables to compare to new ones

  228.     memcpy(&old_spectrum_params, &sbr->spectrum_params, sizeof(SpectrumParameters));

  229. 

  230.     sbr->bs_amp_res_header              = get_bits1(gb);

  231.     sbr->spectrum_params.bs_start_freq  = get_bits(gb, 4);

  232.     sbr->spectrum_params.bs_stop_freq   = get_bits(gb, 4);

  233.     sbr->spectrum_params.bs_xover_band  = get_bits(gb, 3);

  234.                                           skip_bits(gb, 2); // bs_reserved

  235. 

  236.     bs_header_extra_1 = get_bits1(gb);

  237.     bs_header_extra_2 = get_bits1(gb);

  238. 

  239.     if (bs_header_extra_1) {

  240.         sbr->spectrum_params.bs_freq_scale  = get_bits(gb, 2);

  241.         sbr->spectrum_params.bs_alter_scale = get_bits1(gb);

  242.         sbr->spectrum_params.bs_noise_bands = get_bits(gb, 2);

  243.     } else {

  244.         sbr->spectrum_params.bs_freq_scale  = 2;

  245.         sbr->spectrum_params.bs_alter_scale = 1;

  246.         sbr->spectrum_params.bs_noise_bands = 2;

  247.     }

  248. 

  249.     // Check if spectrum parameters changed

  250.     if (memcmp(&old_spectrum_params, &sbr->spectrum_params, sizeof(SpectrumParameters)))

  251.         sbr->reset = 1;

  252. 

  253.     if (bs_header_extra_2) {

  254.         sbr->bs_limiter_bands  = get_bits(gb, 2);

  255.         sbr->bs_limiter_gains  = get_bits(gb, 2);

  256.         sbr->bs_interpol_freq  = get_bits1(gb);

  257.         sbr->bs_smoothing_mode = get_bits1(gb);

  258.     } else {

  259.         sbr->bs_limiter_bands  = 2;

  260.         sbr->bs_limiter_gains  = 2;

  261.         sbr->bs_interpol_freq  = 1;

  262.         sbr->bs_smoothing_mode = 1;

  263.     }

  264. 

  265.     if (sbr->bs_limiter_bands != old_bs_limiter_bands && !sbr->reset)

  266.         sbr_make_f_tablelim(sbr);

  267. 

  268.     return get_bits_count(gb) - cnt;

  269. }

  270. 

  271. static int array_min_int16(const int16_t *array, int nel)

  272. {

  273.     int i, min = array[0];

  274.     for (i = 1; i < nel; i++)

  275.         min = FFMIN(array[i], min);

  276.     return min;

  277. }

  278. 

  279. static void make_bands(int16_t* bands, int start, int stop, int num_bands)

  280. {

  281.     int k, previous, present;

  282.     float base, prod;

  283. 

  284.     base = powf((float)stop / start, 1.0f / num_bands);

  285.     prod = start;

  286.     previous = start;

  287. 

  288.     for (k = 0; k < num_bands-1; k++) {

  289.         prod *= base;

  290.         present  = lrintf(prod);

  291.         bands[k] = present - previous;

  292.         previous = present;

  293.     }

  294.     bands[num_bands-1] = stop - previous;

  295. }

  296. 

  297. static int check_n_master(AVCodecContext *avctx, int n_master, int bs_xover_band)

  298. {

  299.     // Requirements (14496-3 sp04 p205)

  300.     if (n_master <= 0) {

  301.         av_log(avctx, AV_LOG_ERROR, "Invalid n_master: %d\n", n_master);

  302.         return -1;

  303.     }

  304.     if (bs_xover_band >= n_master) {

  305.         av_log(avctx, AV_LOG_ERROR,

  306.                "Invalid bitstream, crossover band index beyond array bounds: %d\n",

  307.                bs_xover_band);

  308.         return -1;

  309.     }

  310.     return 0;

  311. }

  312. 

  313. /// Master Frequency Band Table (14496-3 sp04 p194)

  314. static int sbr_make_f_master(AACContext *ac, SpectralBandReplication *sbr,

  315.                              SpectrumParameters *spectrum)

  316. {

  317.     unsigned int temp, max_qmf_subbands;

  318.     unsigned int start_min, stop_min;

  319.     int k;

  320.     const int8_t *sbr_offset_ptr;

  321.     int16_t stop_dk[13];

  322. 

  323.     if (sbr->sample_rate < 32000) {

  324.         temp = 3000;

  325.     } else if (sbr->sample_rate < 64000) {

  326.         temp = 4000;

  327.     } else

  328.         temp = 5000;

  329. 

  330.     start_min = ((temp << 7) + (sbr->sample_rate >> 1)) / sbr->sample_rate;

  331.     stop_min  = ((temp << 8) + (sbr->sample_rate >> 1)) / sbr->sample_rate;

  332. 

  333.     switch (sbr->sample_rate) {

  334.     case 16000:

  335.         sbr_offset_ptr = sbr_offset[0];

  336.         break;

  337.     case 22050:

  338.         sbr_offset_ptr = sbr_offset[1];

  339.         break;

  340.     case 24000:

  341.         sbr_offset_ptr = sbr_offset[2];

  342.         break;

  343.     case 32000:

  344.         sbr_offset_ptr = sbr_offset[3];

  345.         break;

  346.     case 44100: case 48000: case 64000:

  347.         sbr_offset_ptr = sbr_offset[4];

  348.         break;

  349.     case 88200: case 96000: case 128000: case 176400: case 192000:

  350.         sbr_offset_ptr = sbr_offset[5];

  351.         break;

  352.     default:

  353.         av_log(ac->avctx, AV_LOG_ERROR,

  354.                "Unsupported sample rate for SBR: %d\n", sbr->sample_rate);

  355.         return -1;

  356.     }

  357. 

  358.     sbr->k[0] = start_min + sbr_offset_ptr[spectrum->bs_start_freq];

  359. 

  360.     if (spectrum->bs_stop_freq < 14) {

  361.         sbr->k[2] = stop_min;

  362.         make_bands(stop_dk, stop_min, 64, 13);

  363.         qsort(stop_dk, 13, sizeof(stop_dk[0]), qsort_comparison_function_int16);

  364.         for (k = 0; k < spectrum->bs_stop_freq; k++)

  365.             sbr->k[2] += stop_dk[k];

  366.     } else if (spectrum->bs_stop_freq == 14) {

  367.         sbr->k[2] = 2*sbr->k[0];

  368.     } else if (spectrum->bs_stop_freq == 15) {

  369.         sbr->k[2] = 3*sbr->k[0];

  370.     } else {

  371.         av_log(ac->avctx, AV_LOG_ERROR,

  372.                "Invalid bs_stop_freq: %d\n", spectrum->bs_stop_freq);

  373.         return -1;

  374.     }

  375.     sbr->k[2] = FFMIN(64, sbr->k[2]);

  376. 

  377.     // Requirements (14496-3 sp04 p205)

  378.     if (sbr->sample_rate <= 32000) {

  379.         max_qmf_subbands = 48;

  380.     } else if (sbr->sample_rate == 44100) {

  381.         max_qmf_subbands = 35;

  382.     } else if (sbr->sample_rate >= 48000)

  383.         max_qmf_subbands = 32;

  384. 

  385.     if (sbr->k[2] - sbr->k[0] > max_qmf_subbands) {

  386.         av_log(ac->avctx, AV_LOG_ERROR,

  387.                "Invalid bitstream, too many QMF subbands: %d\n", sbr->k[2] - sbr->k[0]);

  388.         return -1;

  389.     }

  390. 

  391.     if (!spectrum->bs_freq_scale) {

  392.         int dk, k2diff;

  393. 

  394.         dk = spectrum->bs_alter_scale + 1;

  395.         sbr->n_master = ((sbr->k[2] - sbr->k[0] + (dk&2)) >> dk) << 1;

  396.         if (check_n_master(ac->avctx, sbr->n_master, sbr->spectrum_params.bs_xover_band))

  397.             return -1;

  398. 

  399.         for (k = 1; k <= sbr->n_master; k++)

  400.             sbr->f_master[k] = dk;

  401. 

  402.         k2diff = sbr->k[2] - sbr->k[0] - sbr->n_master * dk;

  403.         if (k2diff < 0) {

  404.             sbr->f_master[1]--;

  405.             sbr->f_master[2]-= (k2diff < -1);

  406.         } else if (k2diff) {

  407.             sbr->f_master[sbr->n_master]++;

  408.         }

  409. 

  410.         sbr->f_master[0] = sbr->k[0];

  411.         for (k = 1; k <= sbr->n_master; k++)

  412.             sbr->f_master[k] += sbr->f_master[k - 1];

  413. 

  414.     } else {

  415.         int half_bands = 7 - spectrum->bs_freq_scale;      // bs_freq_scale  = {1,2,3}

  416.         int two_regions, num_bands_0;

  417.         int vdk0_max, vdk1_min;

  418.         int16_t vk0[49];

  419. 

  420.         if (49 * sbr->k[2] > 110 * sbr->k[0]) {

  421.             two_regions = 1;

  422.             sbr->k[1] = 2 * sbr->k[0];

  423.         } else {

  424.             two_regions = 0;

  425.             sbr->k[1] = sbr->k[2];

  426.         }

  427. 

  428.         num_bands_0 = lrintf(half_bands * log2f(sbr->k[1] / (float)sbr->k[0])) * 2;

  429. 

  430.         if (num_bands_0 <= 0) { // Requirements (14496-3 sp04 p205)

  431.             av_log(ac->avctx, AV_LOG_ERROR, "Invalid num_bands_0: %d\n", num_bands_0);

  432.             return -1;

  433.         }

  434. 

  435.         vk0[0] = 0;

  436. 

  437.         make_bands(vk0+1, sbr->k[0], sbr->k[1], num_bands_0);

  438. 

  439.         qsort(vk0 + 1, num_bands_0, sizeof(vk0[1]), qsort_comparison_function_int16);

  440.         vdk0_max = vk0[num_bands_0];

  441. 

  442.         vk0[0] = sbr->k[0];

  443.         for (k = 1; k <= num_bands_0; k++) {

  444.             if (vk0[k] <= 0) { // Requirements (14496-3 sp04 p205)

  445.                 av_log(ac->avctx, AV_LOG_ERROR, "Invalid vDk0[%d]: %d\n", k, vk0[k]);

  446.                 return -1;

  447.             }

  448.             vk0[k] += vk0[k-1];

  449.         }

  450. 

  451.         if (two_regions) {

  452.             int16_t vk1[49];

  453.             float invwarp = spectrum->bs_alter_scale ? 0.76923076923076923077f

  454.                                                      : 1.0f; // bs_alter_scale = {0,1}

  455.             int num_bands_1 = lrintf(half_bands * invwarp *

  456.                                      log2f(sbr->k[2] / (float)sbr->k[1])) * 2;

  457. 

  458.             make_bands(vk1+1, sbr->k[1], sbr->k[2], num_bands_1);

  459. 

  460.             vdk1_min = array_min_int16(vk1 + 1, num_bands_1);

  461. 

  462.             if (vdk1_min < vdk0_max) {

  463.                 int change;

  464.                 qsort(vk1 + 1, num_bands_1, sizeof(vk1[1]), qsort_comparison_function_int16);

  465.                 change = FFMIN(vdk0_max - vk1[1], (vk1[num_bands_1] - vk1[1]) >> 1);

  466.                 vk1[1]           += change;

  467.                 vk1[num_bands_1] -= change;

  468.             }

  469. 

  470.             qsort(vk1 + 1, num_bands_1, sizeof(vk1[1]), qsort_comparison_function_int16);

  471. 

  472.             vk1[0] = sbr->k[1];

  473.             for (k = 1; k <= num_bands_1; k++) {

  474.                 if (vk1[k] <= 0) { // Requirements (14496-3 sp04 p205)

  475.                     av_log(ac->avctx, AV_LOG_ERROR, "Invalid vDk1[%d]: %d\n", k, vk1[k]);

  476.                     return -1;

  477.                 }

  478.                 vk1[k] += vk1[k-1];

  479.             }

  480. 

  481.             sbr->n_master = num_bands_0 + num_bands_1;

  482.             if (check_n_master(ac->avctx, sbr->n_master, sbr->spectrum_params.bs_xover_band))

  483.                 return -1;

  484.             memcpy(&sbr->f_master[0],               vk0,

  485.                    (num_bands_0 + 1) * sizeof(sbr->f_master[0]));

  486.             memcpy(&sbr->f_master[num_bands_0 + 1], vk1 + 1,

  487.                     num_bands_1      * sizeof(sbr->f_master[0]));

  488. 

  489.         } else {

  490.             sbr->n_master = num_bands_0;

  491.             if (check_n_master(ac->avctx, sbr->n_master, sbr->spectrum_params.bs_xover_band))

  492.                 return -1;

  493.             memcpy(sbr->f_master, vk0, (num_bands_0 + 1) * sizeof(sbr->f_master[0]));

  494.         }

  495.     }

  496. 

  497.     return 0;

  498. }

  499. 

  500. /// High Frequency Generation - Patch Construction (14496-3 sp04 p216 fig. 4.46)

  501. static int sbr_hf_calc_npatches(AACContext *ac, SpectralBandReplication *sbr)

  502. {

  503.     int i, k, sb = 0;

  504.     int msb = sbr->k[0];

  505.     int usb = sbr->kx[1];

  506.     int goal_sb = ((1000 << 11) + (sbr->sample_rate >> 1)) / sbr->sample_rate;

  507. 

  508.     sbr->num_patches = 0;

  509. 

  510.     if (goal_sb < sbr->kx[1] + sbr->m[1]) {

  511.         for (k = 0; sbr->f_master[k] < goal_sb; k++) ;

  512.     } else

  513.         k = sbr->n_master;

  514. 

  515.     do {

  516.         int odd = 0;

  517.         for (i = k; i == k || sb > (sbr->k[0] - 1 + msb - odd); i--) {

  518.             sb = sbr->f_master[i];

  519.             odd = (sb + sbr->k[0]) & 1;

  520.         }

  521. 

  522.         // Requirements (14496-3 sp04 p205) sets the maximum number of patches to 5.

  523.         // After this check the final number of patches can still be six which is

  524.         // illegal however the Coding Technologies decoder check stream has a final

  525.         // count of 6 patches

  526.         if (sbr->num_patches > 5) {

  527.             av_log(ac->avctx, AV_LOG_ERROR, "Too many patches: %d\n", sbr->num_patches);

  528.             return -1;

  529.         }

  530. 

  531.         sbr->patch_num_subbands[sbr->num_patches]  = FFMAX(sb - usb, 0);

  532.         sbr->patch_start_subband[sbr->num_patches] = sbr->k[0] - odd - sbr->patch_num_subbands[sbr->num_patches];

  533. 

  534.         if (sbr->patch_num_subbands[sbr->num_patches] > 0) {

  535.             usb = sb;

  536.             msb = sb;

  537.             sbr->num_patches++;

  538.         } else

  539.             msb = sbr->kx[1];

  540. 

  541.         if (sbr->f_master[k] - sb < 3)

  542.             k = sbr->n_master;

  543.     } while (sb != sbr->kx[1] + sbr->m[1]);

  544. 

  545.     if (sbr->patch_num_subbands[sbr->num_patches-1] < 3 && sbr->num_patches > 1)

  546.         sbr->num_patches--;

  547. 

  548.     return 0;

  549. }

  550. 

  551. /// Derived Frequency Band Tables (14496-3 sp04 p197)

  552. static int sbr_make_f_derived(AACContext *ac, SpectralBandReplication *sbr)

  553. {

  554.     int k, temp;

  555. 

  556.     sbr->n[1] = sbr->n_master - sbr->spectrum_params.bs_xover_band;

  557.     sbr->n[0] = (sbr->n[1] + 1) >> 1;

  558. 

  559.     memcpy(sbr->f_tablehigh, &sbr->f_master[sbr->spectrum_params.bs_xover_band],

  560.            (sbr->n[1] + 1) * sizeof(sbr->f_master[0]));

  561.     sbr->m[1] = sbr->f_tablehigh[sbr->n[1]] - sbr->f_tablehigh[0];

  562.     sbr->kx[1] = sbr->f_tablehigh[0];

  563. 

  564.     // Requirements (14496-3 sp04 p205)

  565.     if (sbr->kx[1] + sbr->m[1] > 64) {

  566.         av_log(ac->avctx, AV_LOG_ERROR,

  567.                "Stop frequency border too high: %d\n", sbr->kx[1] + sbr->m[1]);

  568.         return -1;

  569.     }

  570.     if (sbr->kx[1] > 32) {

  571.         av_log(ac->avctx, AV_LOG_ERROR, "Start frequency border too high: %d\n", sbr->kx[1]);

  572.         return -1;

  573.     }

  574. 

  575.     sbr->f_tablelow[0] = sbr->f_tablehigh[0];

  576.     temp = sbr->n[1] & 1;

  577.     for (k = 1; k <= sbr->n[0]; k++)

  578.         sbr->f_tablelow[k] = sbr->f_tablehigh[2 * k - temp];

  579. 

  580.     sbr->n_q = FFMAX(1, lrintf(sbr->spectrum_params.bs_noise_bands *

  581.                                log2f(sbr->k[2] / (float)sbr->kx[1]))); // 0 <= bs_noise_bands <= 3

  582.     if (sbr->n_q > 5) {

  583.         av_log(ac->avctx, AV_LOG_ERROR, "Too many noise floor scale factors: %d\n", sbr->n_q);

  584.         return -1;

  585.     }

  586. 

  587.     sbr->f_tablenoise[0] = sbr->f_tablelow[0];

  588.     temp = 0;

  589.     for (k = 1; k <= sbr->n_q; k++) {

  590.         temp += (sbr->n[0] - temp) / (sbr->n_q + 1 - k);

  591.         sbr->f_tablenoise[k] = sbr->f_tablelow[temp];

  592.     }

  593. 

  594.     if (sbr_hf_calc_npatches(ac, sbr) < 0)

  595.         return -1;

  596. 

  597.     sbr_make_f_tablelim(sbr);

  598. 

  599.     sbr->data[0].f_indexnoise = 0;

  600.     sbr->data[1].f_indexnoise = 0;

  601. 

  602.     return 0;

  603. }

  604. 

  605. static av_always_inline void get_bits1_vector(GetBitContext *gb, uint8_t *vec,

  606.                                               int elements)

  607. {

  608.     int i;

  609.     for (i = 0; i < elements; i++) {

  610.         vec[i] = get_bits1(gb);

  611.     }

  612. }

  613. 

  614. /** ceil(log2(index+1)) */

  615. static const int8_t ceil_log2[] = {

  616.     0, 1, 2, 2, 3, 3,

  617. };

  618. 

  619. static int read_sbr_grid(AACContext *ac, SpectralBandReplication *sbr,

  620.                          GetBitContext *gb, SBRData *ch_data)

  621. {

  622.     int i;

  623.     unsigned bs_pointer = 0;

  624.     // frameLengthFlag ? 15 : 16; 960 sample length frames unsupported; this value is numTimeSlots

  625.     int abs_bord_trail = 16;

  626.     int num_rel_lead, num_rel_trail;

  627.     unsigned bs_num_env_old = ch_data->bs_num_env;

  628. 

  629.     ch_data->bs_freq_res[0] = ch_data->bs_freq_res[ch_data->bs_num_env];

  630.     ch_data->bs_amp_res = sbr->bs_amp_res_header;

  631.     ch_data->t_env_num_env_old = ch_data->t_env[bs_num_env_old];

  632. 

  633.     switch (ch_data->bs_frame_class = get_bits(gb, 2)) {

  634.     case FIXFIX:

  635.         ch_data->bs_num_env                 = 1 << get_bits(gb, 2);

  636.         num_rel_lead                        = ch_data->bs_num_env - 1;

  637.         if (ch_data->bs_num_env == 1)

  638.             ch_data->bs_amp_res = 0;

  639. 

  640.         if (ch_data->bs_num_env > 4) {

  641.             av_log(ac->avctx, AV_LOG_ERROR,

  642.                    "Invalid bitstream, too many SBR envelopes in FIXFIX type SBR frame: %d\n",

  643.                    ch_data->bs_num_env);

  644.             return -1;

  645.         }

  646. 

  647.         ch_data->t_env[0]                   = 0;

  648.         ch_data->t_env[ch_data->bs_num_env] = abs_bord_trail;

  649. 

  650.         abs_bord_trail = (abs_bord_trail + (ch_data->bs_num_env >> 1)) /

  651.                    ch_data->bs_num_env;

  652.         for (i = 0; i < num_rel_lead; i++)

  653.             ch_data->t_env[i + 1] = ch_data->t_env[i] + abs_bord_trail;

  654. 

  655.         ch_data->bs_freq_res[1] = get_bits1(gb);

  656.         for (i = 1; i < ch_data->bs_num_env; i++)

  657.             ch_data->bs_freq_res[i + 1] = ch_data->bs_freq_res[1];

  658.         break;

  659.     case FIXVAR:

  660.         abs_bord_trail                     += get_bits(gb, 2);

  661.         num_rel_trail                       = get_bits(gb, 2);

  662.         ch_data->bs_num_env                 = num_rel_trail + 1;

  663.         ch_data->t_env[0]                   = 0;

  664.         ch_data->t_env[ch_data->bs_num_env] = abs_bord_trail;

  665. 

  666.         for (i = 0; i < num_rel_trail; i++)

  667.             ch_data->t_env[ch_data->bs_num_env - 1 - i] =

  668.                 ch_data->t_env[ch_data->bs_num_env - i] - 2 * get_bits(gb, 2) - 2;

  669. 

  670.         bs_pointer = get_bits(gb, ceil_log2[ch_data->bs_num_env]);

  671. 

  672.         for (i = 0; i < ch_data->bs_num_env; i++)

  673.             ch_data->bs_freq_res[ch_data->bs_num_env - i] = get_bits1(gb);

  674.         break;

  675.     case VARFIX:

  676.         ch_data->t_env[0]                   = get_bits(gb, 2);

  677.         num_rel_lead                        = get_bits(gb, 2);

  678.         ch_data->bs_num_env                 = num_rel_lead + 1;

  679.         ch_data->t_env[ch_data->bs_num_env] = abs_bord_trail;

  680. 

  681.         for (i = 0; i < num_rel_lead; i++)

  682.             ch_data->t_env[i + 1] = ch_data->t_env[i] + 2 * get_bits(gb, 2) + 2;

  683. 

  684.         bs_pointer = get_bits(gb, ceil_log2[ch_data->bs_num_env]);

  685. 

  686.         get_bits1_vector(gb, ch_data->bs_freq_res + 1, ch_data->bs_num_env);

  687.         break;

  688.     case VARVAR:

  689.         ch_data->t_env[0]                   = get_bits(gb, 2);

  690.         abs_bord_trail                     += get_bits(gb, 2);

  691.         num_rel_lead                        = get_bits(gb, 2);

  692.         num_rel_trail                       = get_bits(gb, 2);

  693.         ch_data->bs_num_env                 = num_rel_lead + num_rel_trail + 1;

  694. 

  695.         if (ch_data->bs_num_env > 5) {

  696.             av_log(ac->avctx, AV_LOG_ERROR,

  697.                    "Invalid bitstream, too many SBR envelopes in VARVAR type SBR frame: %d\n",

  698.                    ch_data->bs_num_env);

  699.             return -1;

  700.         }

  701. 

  702.         ch_data->t_env[ch_data->bs_num_env] = abs_bord_trail;

  703. 

  704.         for (i = 0; i < num_rel_lead; i++)

  705.             ch_data->t_env[i + 1] = ch_data->t_env[i] + 2 * get_bits(gb, 2) + 2;

  706.         for (i = 0; i < num_rel_trail; i++)

  707.             ch_data->t_env[ch_data->bs_num_env - 1 - i] =

  708.                 ch_data->t_env[ch_data->bs_num_env - i] - 2 * get_bits(gb, 2) - 2;

  709. 

  710.         bs_pointer = get_bits(gb, ceil_log2[ch_data->bs_num_env]);

  711. 

  712.         get_bits1_vector(gb, ch_data->bs_freq_res + 1, ch_data->bs_num_env);

  713.         break;

  714.     }

  715. 

  716.     if (bs_pointer > ch_data->bs_num_env + 1) {

  717.         av_log(ac->avctx, AV_LOG_ERROR,

  718.                "Invalid bitstream, bs_pointer points to a middle noise border outside the time borders table: %d\n",

  719.                bs_pointer);

  720.         return -1;

  721.     }

  722. 

  723.     for (i = 1; i <= ch_data->bs_num_env; i++) {

  724.         if (ch_data->t_env[i-1] > ch_data->t_env[i]) {

  725.             av_log(ac->avctx, AV_LOG_ERROR, "Non monotone time borders\n");

  726.             return -1;

  727.         }

  728.     }

  729. 

  730.     ch_data->bs_num_noise = (ch_data->bs_num_env > 1) + 1;

  731. 

  732.     ch_data->t_q[0]                     = ch_data->t_env[0];

  733.     ch_data->t_q[ch_data->bs_num_noise] = ch_data->t_env[ch_data->bs_num_env];

  734.     if (ch_data->bs_num_noise > 1) {

  735.         unsigned int idx;

  736.         if (ch_data->bs_frame_class == FIXFIX) {

  737.             idx = ch_data->bs_num_env >> 1;

  738.         } else if (ch_data->bs_frame_class & 1) { // FIXVAR or VARVAR

  739.             idx = ch_data->bs_num_env - FFMAX(bs_pointer - 1, 1);

  740.         } else { // VARFIX

  741.             if (!bs_pointer)

  742.                 idx = 1;

  743.             else if (bs_pointer == 1)

  744.                 idx = ch_data->bs_num_env - 1;

  745.             else // bs_pointer > 1

  746.                 idx = bs_pointer - 1;

  747.         }

  748.         ch_data->t_q[1] = ch_data->t_env[idx];

  749.     }

  750. 

  751.     ch_data->e_a[0] = -(ch_data->e_a[1] != bs_num_env_old); // l_APrev

  752.     ch_data->e_a[1] = -1;

  753.     if ((ch_data->bs_frame_class & 1) && bs_pointer) { // FIXVAR or VARVAR and bs_pointer != 0

  754.         ch_data->e_a[1] = ch_data->bs_num_env + 1 - bs_pointer;

  755.     } else if ((ch_data->bs_frame_class == 2) && (bs_pointer > 1)) // VARFIX and bs_pointer > 1

  756.         ch_data->e_a[1] = bs_pointer - 1;

  757. 

  758.     return 0;

  759. }

  760. 

  761. static void copy_sbr_grid(SBRData *dst, const SBRData *src) {

  762.     //These variables are saved from the previous frame rather than copied

  763.     dst->bs_freq_res[0]    = dst->bs_freq_res[dst->bs_num_env];

  764.     dst->t_env_num_env_old = dst->t_env[dst->bs_num_env];

  765.     dst->e_a[0]            = -(dst->e_a[1] != dst->bs_num_env);

  766. 

  767.     //These variables are read from the bitstream and therefore copied

  768.     memcpy(dst->bs_freq_res+1, src->bs_freq_res+1, sizeof(dst->bs_freq_res)-sizeof(*dst->bs_freq_res));

  769.     memcpy(dst->t_env,         src->t_env,         sizeof(dst->t_env));

  770.     memcpy(dst->t_q,           src->t_q,           sizeof(dst->t_q));

  771.     dst->bs_num_env        = src->bs_num_env;

  772.     dst->bs_amp_res        = src->bs_amp_res;

  773.     dst->bs_num_noise      = src->bs_num_noise;

  774.     dst->bs_frame_class    = src->bs_frame_class;

  775.     dst->e_a[1]            = src->e_a[1];

  776. }

  777. 

  778. /// Read how the envelope and noise floor data is delta coded

  779. static void read_sbr_dtdf(SpectralBandReplication *sbr, GetBitContext *gb,

  780.                           SBRData *ch_data)

  781. {

  782.     get_bits1_vector(gb, ch_data->bs_df_env,   ch_data->bs_num_env);

  783.     get_bits1_vector(gb, ch_data->bs_df_noise, ch_data->bs_num_noise);

  784. }

  785. 

  786. /// Read inverse filtering data

  787. static void read_sbr_invf(SpectralBandReplication *sbr, GetBitContext *gb,

  788.                           SBRData *ch_data)

  789. {

  790.     int i;

  791. 

  792.     memcpy(ch_data->bs_invf_mode[1], ch_data->bs_invf_mode[0], 5 * sizeof(uint8_t));

  793.     for (i = 0; i < sbr->n_q; i++)

  794.         ch_data->bs_invf_mode[0][i] = get_bits(gb, 2);

  795. }

  796. 

  797. static void read_sbr_envelope(SpectralBandReplication *sbr, GetBitContext *gb,

  798.                               SBRData *ch_data, int ch)

  799. {

  800.     int bits;

  801.     int i, j, k;

  802.     VLC_TYPE (*t_huff)[2], (*f_huff)[2];

  803.     int t_lav, f_lav;

  804.     const int delta = (ch == 1 && sbr->bs_coupling == 1) + 1;

  805.     const int odd = sbr->n[1] & 1;

  806. 

  807.     if (sbr->bs_coupling && ch) {

  808.         if (ch_data->bs_amp_res) {

  809.             bits   = 5;

  810.             t_huff = vlc_sbr[T_HUFFMAN_ENV_BAL_3_0DB].table;

  811.             t_lav  = vlc_sbr_lav[T_HUFFMAN_ENV_BAL_3_0DB];

  812.             f_huff = vlc_sbr[F_HUFFMAN_ENV_BAL_3_0DB].table;

  813.             f_lav  = vlc_sbr_lav[F_HUFFMAN_ENV_BAL_3_0DB];

  814.         } else {

  815.             bits   = 6;

  816.             t_huff = vlc_sbr[T_HUFFMAN_ENV_BAL_1_5DB].table;

  817.             t_lav  = vlc_sbr_lav[T_HUFFMAN_ENV_BAL_1_5DB];

  818.             f_huff = vlc_sbr[F_HUFFMAN_ENV_BAL_1_5DB].table;

  819.             f_lav  = vlc_sbr_lav[F_HUFFMAN_ENV_BAL_1_5DB];

  820.         }

  821.     } else {

  822.         if (ch_data->bs_amp_res) {

  823.             bits   = 6;

  824.             t_huff = vlc_sbr[T_HUFFMAN_ENV_3_0DB].table;

  825.             t_lav  = vlc_sbr_lav[T_HUFFMAN_ENV_3_0DB];

  826.             f_huff = vlc_sbr[F_HUFFMAN_ENV_3_0DB].table;

  827.             f_lav  = vlc_sbr_lav[F_HUFFMAN_ENV_3_0DB];

  828.         } else {

  829.             bits   = 7;

  830.             t_huff = vlc_sbr[T_HUFFMAN_ENV_1_5DB].table;

  831.             t_lav  = vlc_sbr_lav[T_HUFFMAN_ENV_1_5DB];

  832.             f_huff = vlc_sbr[F_HUFFMAN_ENV_1_5DB].table;

  833.             f_lav  = vlc_sbr_lav[F_HUFFMAN_ENV_1_5DB];

  834.         }

  835.     }

  836. 

  837.     for (i = 0; i < ch_data->bs_num_env; i++) {

  838.         if (ch_data->bs_df_env[i]) {

  839.             // bs_freq_res[0] == bs_freq_res[bs_num_env] from prev frame

  840.             if (ch_data->bs_freq_res[i + 1] == ch_data->bs_freq_res[i]) {

  841.                 for (j = 0; j < sbr->n[ch_data->bs_freq_res[i + 1]]; j++)

  842.                     ch_data->env_facs[i + 1][j] = ch_data->env_facs[i][j] + delta * (get_vlc2(gb, t_huff, 9, 3) - t_lav);

  843.             } else if (ch_data->bs_freq_res[i + 1]) {

  844.                 for (j = 0; j < sbr->n[ch_data->bs_freq_res[i + 1]]; j++) {

  845.                     k = (j + odd) >> 1; // find k such that f_tablelow[k] <= f_tablehigh[j] < f_tablelow[k + 1]

  846.                     ch_data->env_facs[i + 1][j] = ch_data->env_facs[i][k] + delta * (get_vlc2(gb, t_huff, 9, 3) - t_lav);

  847.                 }

  848.             } else {

  849.                 for (j = 0; j < sbr->n[ch_data->bs_freq_res[i + 1]]; j++) {

  850.                     k = j ? 2*j - odd : 0; // find k such that f_tablehigh[k] == f_tablelow[j]

  851.                     ch_data->env_facs[i + 1][j] = ch_data->env_facs[i][k] + delta * (get_vlc2(gb, t_huff, 9, 3) - t_lav);

  852.                 }

  853.             }

  854.         } else {

  855.             ch_data->env_facs[i + 1][0] = delta * get_bits(gb, bits); // bs_env_start_value_balance

  856.             for (j = 1; j < sbr->n[ch_data->bs_freq_res[i + 1]]; j++)

  857.                 ch_data->env_facs[i + 1][j] = ch_data->env_facs[i + 1][j - 1] + delta * (get_vlc2(gb, f_huff, 9, 3) - f_lav);

  858.         }

  859.     }

  860. 

  861.     //assign 0th elements of env_facs from last elements

  862.     memcpy(ch_data->env_facs[0], ch_data->env_facs[ch_data->bs_num_env],

  863.            sizeof(ch_data->env_facs[0]));

  864. }

  865. 

  866. static void read_sbr_noise(SpectralBandReplication *sbr, GetBitContext *gb,

  867.                            SBRData *ch_data, int ch)

  868. {

  869.     int i, j;

  870.     VLC_TYPE (*t_huff)[2], (*f_huff)[2];

  871.     int t_lav, f_lav;

  872.     int delta = (ch == 1 && sbr->bs_coupling == 1) + 1;

  873. 

  874.     if (sbr->bs_coupling && ch) {

  875.         t_huff = vlc_sbr[T_HUFFMAN_NOISE_BAL_3_0DB].table;

  876.         t_lav  = vlc_sbr_lav[T_HUFFMAN_NOISE_BAL_3_0DB];

  877.         f_huff = vlc_sbr[F_HUFFMAN_ENV_BAL_3_0DB].table;

  878.         f_lav  = vlc_sbr_lav[F_HUFFMAN_ENV_BAL_3_0DB];

  879.     } else {

  880.         t_huff = vlc_sbr[T_HUFFMAN_NOISE_3_0DB].table;

  881.         t_lav  = vlc_sbr_lav[T_HUFFMAN_NOISE_3_0DB];

  882.         f_huff = vlc_sbr[F_HUFFMAN_ENV_3_0DB].table;

  883.         f_lav  = vlc_sbr_lav[F_HUFFMAN_ENV_3_0DB];

  884.     }

  885. 

  886.     for (i = 0; i < ch_data->bs_num_noise; i++) {

  887.         if (ch_data->bs_df_noise[i]) {

  888.             for (j = 0; j < sbr->n_q; j++)

  889.                 ch_data->noise_facs[i + 1][j] = ch_data->noise_facs[i][j] + delta * (get_vlc2(gb, t_huff, 9, 2) - t_lav);

  890.         } else {

  891.             ch_data->noise_facs[i + 1][0] = delta * get_bits(gb, 5); // bs_noise_start_value_balance or bs_noise_start_value_level

  892.             for (j = 1; j < sbr->n_q; j++)

  893.                 ch_data->noise_facs[i + 1][j] = ch_data->noise_facs[i + 1][j - 1] + delta * (get_vlc2(gb, f_huff, 9, 3) - f_lav);

  894.         }

  895.     }

  896. 

  897.     //assign 0th elements of noise_facs from last elements

  898.     memcpy(ch_data->noise_facs[0], ch_data->noise_facs[ch_data->bs_num_noise],

  899.            sizeof(ch_data->noise_facs[0]));

  900. }

  901. 

  902. static void read_sbr_extension(AACContext *ac, SpectralBandReplication *sbr,

  903.                                GetBitContext *gb,

  904.                                int bs_extension_id, int *num_bits_left)

  905. {

  906.     switch (bs_extension_id) {

  907.     case EXTENSION_ID_PS:

  908.         if (!ac->m4ac.ps) {

  909.             av_log(ac->avctx, AV_LOG_ERROR, "Parametric Stereo signaled to be not-present but was found in the bitstream.\n");

  910.             skip_bits_long(gb, *num_bits_left); // bs_fill_bits

  911.             *num_bits_left = 0;

  912.         } else {

  913. #if 1

  914.             *num_bits_left -= ff_ps_read_data(ac->avctx, gb, &sbr->ps, *num_bits_left);

  915. #else

  916.             av_log_missing_feature(ac->avctx, "Parametric Stereo is", 0);

  917.             skip_bits_long(gb, *num_bits_left); // bs_fill_bits

  918.             *num_bits_left = 0;

  919. #endif

  920.         }

  921.         break;

  922.     default:

  923.         av_log_missing_feature(ac->avctx, "Reserved SBR extensions are", 1);

  924.         skip_bits_long(gb, *num_bits_left); // bs_fill_bits

  925.         *num_bits_left = 0;

  926.         break;

  927.     }

  928. }

  929. 

  930. static int read_sbr_single_channel_element(AACContext *ac,

  931.                                             SpectralBandReplication *sbr,

  932.                                             GetBitContext *gb)

  933. {

  934.     if (get_bits1(gb)) // bs_data_extra

  935.         skip_bits(gb, 4); // bs_reserved

  936. 

  937.     if (read_sbr_grid(ac, sbr, gb, &sbr->data[0]))

  938.         return -1;

  939.     read_sbr_dtdf(sbr, gb, &sbr->data[0]);

  940.     read_sbr_invf(sbr, gb, &sbr->data[0]);

  941.     read_sbr_envelope(sbr, gb, &sbr->data[0], 0);

  942.     read_sbr_noise(sbr, gb, &sbr->data[0], 0);

  943. 

  944.     if ((sbr->data[0].bs_add_harmonic_flag = get_bits1(gb)))

  945.         get_bits1_vector(gb, sbr->data[0].bs_add_harmonic, sbr->n[1]);

  946. 

  947.     return 0;

  948. }

  949. 

  950. static int read_sbr_channel_pair_element(AACContext *ac,

  951.                                           SpectralBandReplication *sbr,

  952.                                           GetBitContext *gb)

  953. {

  954.     if (get_bits1(gb))    // bs_data_extra

  955.         skip_bits(gb, 8); // bs_reserved

  956. 

  957.     if ((sbr->bs_coupling = get_bits1(gb))) {

  958.         if (read_sbr_grid(ac, sbr, gb, &sbr->data[0]))

  959.             return -1;

  960.         copy_sbr_grid(&sbr->data[1], &sbr->data[0]);

  961.         read_sbr_dtdf(sbr, gb, &sbr->data[0]);

  962.         read_sbr_dtdf(sbr, gb, &sbr->data[1]);

  963.         read_sbr_invf(sbr, gb, &sbr->data[0]);

  964.         memcpy(sbr->data[1].bs_invf_mode[1], sbr->data[1].bs_invf_mode[0], sizeof(sbr->data[1].bs_invf_mode[0]));

  965.         memcpy(sbr->data[1].bs_invf_mode[0], sbr->data[0].bs_invf_mode[0], sizeof(sbr->data[1].bs_invf_mode[0]));

  966.         read_sbr_envelope(sbr, gb, &sbr->data[0], 0);

  967.         read_sbr_noise(sbr, gb, &sbr->data[0], 0);

  968.         read_sbr_envelope(sbr, gb, &sbr->data[1], 1);

  969.         read_sbr_noise(sbr, gb, &sbr->data[1], 1);

  970.     } else {

  971.         if (read_sbr_grid(ac, sbr, gb, &sbr->data[0]) ||

  972.             read_sbr_grid(ac, sbr, gb, &sbr->data[1]))

  973.             return -1;

  974.         read_sbr_dtdf(sbr, gb, &sbr->data[0]);

  975.         read_sbr_dtdf(sbr, gb, &sbr->data[1]);

  976.         read_sbr_invf(sbr, gb, &sbr->data[0]);

  977.         read_sbr_invf(sbr, gb, &sbr->data[1]);

  978.         read_sbr_envelope(sbr, gb, &sbr->data[0], 0);

  979.         read_sbr_envelope(sbr, gb, &sbr->data[1], 1);

  980.         read_sbr_noise(sbr, gb, &sbr->data[0], 0);

  981.         read_sbr_noise(sbr, gb, &sbr->data[1], 1);

  982.     }

  983. 

  984.     if ((sbr->data[0].bs_add_harmonic_flag = get_bits1(gb)))

  985.         get_bits1_vector(gb, sbr->data[0].bs_add_harmonic, sbr->n[1]);

  986.     if ((sbr->data[1].bs_add_harmonic_flag = get_bits1(gb)))

  987.         get_bits1_vector(gb, sbr->data[1].bs_add_harmonic, sbr->n[1]);

  988. 

  989.     return 0;

  990. }

  991. 

  992. static unsigned int read_sbr_data(AACContext *ac, SpectralBandReplication *sbr,

  993.                                   GetBitContext *gb, int id_aac)

  994. {

  995.     unsigned int cnt = get_bits_count(gb);

  996. 

  997.     if (id_aac == TYPE_SCE || id_aac == TYPE_CCE) {

  998.         if (read_sbr_single_channel_element(ac, sbr, gb)) {

  999.             sbr->start = 0;

  1000.             return get_bits_count(gb) - cnt;

  1001.         }

  1002.     } else if (id_aac == TYPE_CPE) {

  1003.         if (read_sbr_channel_pair_element(ac, sbr, gb)) {

  1004.             sbr->start = 0;

  1005.             return get_bits_count(gb) - cnt;

  1006.         }

  1007.     } else {

  1008.         av_log(ac->avctx, AV_LOG_ERROR,

  1009.             "Invalid bitstream - cannot apply SBR to element type %d\n", id_aac);

  1010.         sbr->start = 0;

  1011.         return get_bits_count(gb) - cnt;

  1012.     }

  1013.     if (get_bits1(gb)) { // bs_extended_data

  1014.         int num_bits_left = get_bits(gb, 4); // bs_extension_size

  1015.         if (num_bits_left == 15)

  1016.             num_bits_left += get_bits(gb, 8); // bs_esc_count

  1017. 

  1018.         num_bits_left <<= 3;

  1019.         while (num_bits_left > 7) {

  1020.             num_bits_left -= 2;

  1021.             read_sbr_extension(ac, sbr, gb, get_bits(gb, 2), &num_bits_left); // bs_extension_id

  1022.         }

  1023.         if (num_bits_left < 0) {

  1024.             av_log(ac->avctx, AV_LOG_ERROR, "SBR Extension over read.\n");

  1025.         }

  1026.         if (num_bits_left > 0)

  1027.             skip_bits(gb, num_bits_left);

  1028.     }

  1029. 

  1030.     return get_bits_count(gb) - cnt;

  1031. }

  1032. 

  1033. static void sbr_reset(AACContext *ac, SpectralBandReplication *sbr)

  1034. {

  1035.     int err;

  1036.     err = sbr_make_f_master(ac, sbr, &sbr->spectrum_params);

  1037.     if (err >= 0)

  1038.         err = sbr_make_f_derived(ac, sbr);

  1039.     if (err < 0) {

  1040.         av_log(ac->avctx, AV_LOG_ERROR,

  1041.                "SBR reset failed. Switching SBR to pure upsampling mode.\n");

  1042.         sbr->start = 0;

  1043.     }

  1044. }

  1045. 

  1046. /**

  1047.  * Decode Spectral Band Replication extension data; reference: table 4.55.

  1048.  *

  1049.  * @param   crc flag indicating the presence of CRC checksum

  1050.  * @param   cnt length of TYPE_FIL syntactic element in bytes

  1051.  *

  1052.  * @return  Returns number of bytes consumed from the TYPE_FIL element.

  1053.  */

  1054. int ff_decode_sbr_extension(AACContext *ac, SpectralBandReplication *sbr,

  1055.                             GetBitContext *gb_host, int crc, int cnt, int id_aac)

  1056. {

  1057.     unsigned int num_sbr_bits = 0, num_align_bits;

  1058.     unsigned bytes_read;

  1059.     GetBitContext gbc = *gb_host, *gb = &gbc;

  1060.     skip_bits_long(gb_host, cnt*8 - 4);

  1061. 

  1062.     sbr->reset = 0;

  1063. 

  1064.     if (!sbr->sample_rate)

  1065.         sbr->sample_rate = 2 * ac->m4ac.sample_rate; //TODO use the nominal sample rate for arbitrary sample rate support

  1066.     if (!ac->m4ac.ext_sample_rate)

  1067.         ac->m4ac.ext_sample_rate = 2 * ac->m4ac.sample_rate;

  1068. 

  1069.     if (crc) {

  1070.         skip_bits(gb, 10); // bs_sbr_crc_bits; TODO - implement CRC check

  1071.         num_sbr_bits += 10;

  1072.     }

  1073. 

  1074.     //Save some state from the previous frame.

  1075.     sbr->kx[0] = sbr->kx[1];

  1076.     sbr->m[0] = sbr->m[1];

  1077. 

  1078.     num_sbr_bits++;

  1079.     if (get_bits1(gb)) // bs_header_flag

  1080.         num_sbr_bits += read_sbr_header(sbr, gb);

  1081. 

  1082.     if (sbr->reset)

  1083.         sbr_reset(ac, sbr);

  1084. 

  1085.     if (sbr->start)

  1086.         num_sbr_bits  += read_sbr_data(ac, sbr, gb, id_aac);

  1087. 

  1088.     num_align_bits = ((cnt << 3) - 4 - num_sbr_bits) & 7;

  1089.     bytes_read = ((num_sbr_bits + num_align_bits + 4) >> 3);

  1090. 

  1091.     if (bytes_read > cnt) {

  1092.         av_log(ac->avctx, AV_LOG_ERROR,

  1093.                "Expected to read %d SBR bytes actually read %d.\n", cnt, bytes_read);

  1094.     }

  1095.     return cnt;

  1096. }

  1097. 

  1098. /// Dequantization and stereo decoding (14496-3 sp04 p203)

  1099. static void sbr_dequant(SpectralBandReplication *sbr, int id_aac)

  1100. {

  1101.     int k, e;

  1102.     int ch;

  1103. 

  1104.     if (id_aac == TYPE_CPE && sbr->bs_coupling) {

  1105.         float alpha      = sbr->data[0].bs_amp_res ?  1.0f :  0.5f;

  1106.         float pan_offset = sbr->data[0].bs_amp_res ? 12.0f : 24.0f;

  1107.         for (e = 1; e <= sbr->data[0].bs_num_env; e++) {

  1108.             for (k = 0; k < sbr->n[sbr->data[0].bs_freq_res[e]]; k++) {

  1109.                 float temp1 = exp2f(sbr->data[0].env_facs[e][k] * alpha + 7.0f);

  1110.                 float temp2 = exp2f((pan_offset - sbr->data[1].env_facs[e][k]) * alpha);

  1111.                 float fac   = temp1 / (1.0f + temp2);

  1112.                 sbr->data[0].env_facs[e][k] = fac;

  1113.                 sbr->data[1].env_facs[e][k] = fac * temp2;

  1114.             }

  1115.         }

  1116.         for (e = 1; e <= sbr->data[0].bs_num_noise; e++) {

  1117.             for (k = 0; k < sbr->n_q; k++) {

  1118.                 float temp1 = exp2f(NOISE_FLOOR_OFFSET - sbr->data[0].noise_facs[e][k] + 1);

  1119.                 float temp2 = exp2f(12 - sbr->data[1].noise_facs[e][k]);

  1120.                 float fac   = temp1 / (1.0f + temp2);

  1121.                 sbr->data[0].noise_facs[e][k] = fac;

  1122.                 sbr->data[1].noise_facs[e][k] = fac * temp2;

  1123.             }

  1124.         }

  1125.     } else { // SCE or one non-coupled CPE

  1126.         for (ch = 0; ch < (id_aac == TYPE_CPE) + 1; ch++) {

  1127.             float alpha = sbr->data[ch].bs_amp_res ? 1.0f : 0.5f;

  1128.             for (e = 1; e <= sbr->data[ch].bs_num_env; e++)

  1129.                 for (k = 0; k < sbr->n[sbr->data[ch].bs_freq_res[e]]; k++)

  1130.                     sbr->data[ch].env_facs[e][k] =

  1131.                         exp2f(alpha * sbr->data[ch].env_facs[e][k] + 6.0f);

  1132.             for (e = 1; e <= sbr->data[ch].bs_num_noise; e++)

  1133.                 for (k = 0; k < sbr->n_q; k++)

  1134.                     sbr->data[ch].noise_facs[e][k] =

  1135.                         exp2f(NOISE_FLOOR_OFFSET - sbr->data[ch].noise_facs[e][k]);

  1136.         }

  1137.     }

  1138. }

  1139. 

  1140. /**

  1141.  * Analysis QMF Bank (14496-3 sp04 p206)

  1142.  *

  1143.  * @param   x       pointer to the beginning of the first sample window

  1144.  * @param   W       array of complex-valued samples split into subbands

  1145.  */

  1146. static void sbr_qmf_analysis(DSPContext *dsp, FFTContext *mdct, const float *in, float *x,

  1147.                              float z[320], float W[2][32][32][2])

  1148. {

  1149.     int i, k;

  1150.     memcpy(W[0], W[1], sizeof(W[0]));

  1151.     memcpy(x    , x+1024, (320-32)*sizeof(x[0]));

  1152.     memcpy(x+288, in,         1024*sizeof(x[0]));

  1153.     for (i = 0; i < 32; i++) { // numTimeSlots*RATE = 16*2 as 960 sample frames

  1154.                                // are not supported

  1155.         dsp->vector_fmul_reverse(z, sbr_qmf_window_ds, x, 320);

  1156.         for (k = 0; k < 64; k++) {

  1157.             float f = z[k] + z[k + 64] + z[k + 128] + z[k + 192] + z[k + 256];

  1158.             z[k] = f;

  1159.         }

  1160.         //Shuffle to IMDCT

  1161.         z[64] = z[0];

  1162.         for (k = 1; k < 32; k++) {

  1163.             z[64+2*k-1] =  z[   k];

  1164.             z[64+2*k  ] = -z[64-k];

  1165.         }

  1166.         z[64+63] = z[32];

  1167. 

  1168.         mdct->imdct_half(mdct, z, z+64);

  1169.         for (k = 0; k < 32; k++) {

  1170.             W[1][i][k][0] = -z[63-k];

  1171.             W[1][i][k][1] = z[k];

  1172.         }

  1173.         x += 32;

  1174.     }

  1175. }

  1176. 

  1177. /**

  1178.  * Synthesis QMF Bank (14496-3 sp04 p206) and Downsampled Synthesis QMF Bank

  1179.  * (14496-3 sp04 p206)

  1180.  */

  1181. static void sbr_qmf_synthesis(DSPContext *dsp, FFTContext *mdct,

  1182.                               float *out, float X[2][38][64],

  1183.                               float mdct_buf[2][64],

  1184.                               float *v0, int *v_off, const unsigned int div)

  1185. {

  1186.     int i, n;

  1187.     const float *sbr_qmf_window = div ? sbr_qmf_window_ds : sbr_qmf_window_us;

  1188.     float *v;

  1189.     for (i = 0; i < 32; i++) {

  1190.         if (*v_off == 0) {

  1191.             int saved_samples = (1280 - 128) >> div;

  1192.             memcpy(&v0[SBR_SYNTHESIS_BUF_SIZE - saved_samples], v0, saved_samples * sizeof(float));

  1193.             *v_off = SBR_SYNTHESIS_BUF_SIZE - saved_samples - (128 >> div);

  1194.         } else {

  1195.             *v_off -= 128 >> div;

  1196.         }

  1197.         v = v0 + *v_off;

  1198.         if (div) {

  1199.             for (n = 0; n < 32; n++) {

  1200.                 X[0][i][   n] = -X[0][i][n];

  1201.                 X[0][i][32+n] =  X[1][i][31-n];

  1202.             }

  1203.             mdct->imdct_half(mdct, mdct_buf[0], X[0][i]);

  1204.             for (n = 0; n < 32; n++) {

  1205.                 v[     n] =  mdct_buf[0][63 - 2*n];

  1206.                 v[63 - n] = -mdct_buf[0][62 - 2*n];

  1207.             }

  1208.         } else {

  1209.             for (n = 1; n < 64; n+=2) {

  1210.                 X[1][i][n] = -X[1][i][n];

  1211.             }

  1212.             mdct->imdct_half(mdct, mdct_buf[0], X[0][i]);

  1213.             mdct->imdct_half(mdct, mdct_buf[1], X[1][i]);

  1214.             for (n = 0; n < 64; n++) {

  1215.                 v[      n] = -mdct_buf[0][63 -   n] + mdct_buf[1][  n    ];

  1216.                 v[127 - n] =  mdct_buf[0][63 -   n] + mdct_buf[1][  n    ];

  1217.             }

  1218.         }

  1219.         dsp->vector_fmul_add(out, v                , sbr_qmf_window               , zero64, 64 >> div);

  1220.         dsp->vector_fmul_add(out, v + ( 192 >> div), sbr_qmf_window + ( 64 >> div), out   , 64 >> div);

  1221.         dsp->vector_fmul_add(out, v + ( 256 >> div), sbr_qmf_window + (128 >> div), out   , 64 >> div);

  1222.         dsp->vector_fmul_add(out, v + ( 448 >> div), sbr_qmf_window + (192 >> div), out   , 64 >> div);

  1223.         dsp->vector_fmul_add(out, v + ( 512 >> div), sbr_qmf_window + (256 >> div), out   , 64 >> div);

  1224.         dsp->vector_fmul_add(out, v + ( 704 >> div), sbr_qmf_window + (320 >> div), out   , 64 >> div);

  1225.         dsp->vector_fmul_add(out, v + ( 768 >> div), sbr_qmf_window + (384 >> div), out   , 64 >> div);

  1226.         dsp->vector_fmul_add(out, v + ( 960 >> div), sbr_qmf_window + (448 >> div), out   , 64 >> div);

  1227.         dsp->vector_fmul_add(out, v + (1024 >> div), sbr_qmf_window + (512 >> div), out   , 64 >> div);

  1228.         dsp->vector_fmul_add(out, v + (1216 >> div), sbr_qmf_window + (576 >> div), out   , 64 >> div);

  1229.         out += 64 >> div;

  1230.     }

  1231. }

  1232. 

  1233. static void autocorrelate(const float x[40][2], float phi[3][2][2], int lag)

  1234. {

  1235.     int i;

  1236.     float real_sum = 0.0f;

  1237.     float imag_sum = 0.0f;

  1238.     if (lag) {

  1239.         for (i = 1; i < 38; i++) {

  1240.             real_sum += x[i][0] * x[i+lag][0] + x[i][1] * x[i+lag][1];

  1241.             imag_sum += x[i][0] * x[i+lag][1] - x[i][1] * x[i+lag][0];

  1242.         }

  1243.         phi[2-lag][1][0] = real_sum + x[ 0][0] * x[lag][0] + x[ 0][1] * x[lag][1];

  1244.         phi[2-lag][1][1] = imag_sum + x[ 0][0] * x[lag][1] - x[ 0][1] * x[lag][0];

  1245.         if (lag == 1) {

  1246.             phi[0][0][0] = real_sum + x[38][0] * x[39][0] + x[38][1] * x[39][1];

  1247.             phi[0][0][1] = imag_sum + x[38][0] * x[39][1] - x[38][1] * x[39][0];

  1248.         }

  1249.     } else {

  1250.         for (i = 1; i < 38; i++) {

  1251.             real_sum += x[i][0] * x[i][0] + x[i][1] * x[i][1];

  1252.         }

  1253.         phi[2][1][0] = real_sum + x[ 0][0] * x[ 0][0] + x[ 0][1] * x[ 0][1];

  1254.         phi[1][0][0] = real_sum + x[38][0] * x[38][0] + x[38][1] * x[38][1];

  1255.     }

  1256. }

  1257. 

  1258. /** High Frequency Generation (14496-3 sp04 p214+) and Inverse Filtering

  1259.  * (14496-3 sp04 p214)

  1260.  * Warning: This routine does not seem numerically stable.

  1261.  */

  1262. static void sbr_hf_inverse_filter(float (*alpha0)[2], float (*alpha1)[2],

  1263.                                   const float X_low[32][40][2], int k0)

  1264. {

  1265.     int k;

  1266.     for (k = 0; k < k0; k++) {

  1267.         float phi[3][2][2], dk;

  1268. 

  1269.         autocorrelate(X_low[k], phi, 0);

  1270.         autocorrelate(X_low[k], phi, 1);

  1271.         autocorrelate(X_low[k], phi, 2);

  1272. 

  1273.         dk =  phi[2][1][0] * phi[1][0][0] -

  1274.              (phi[1][1][0] * phi[1][1][0] + phi[1][1][1] * phi[1][1][1]) / 1.000001f;

  1275. 

  1276.         if (!dk) {

  1277.             alpha1[k][0] = 0;

  1278.             alpha1[k][1] = 0;

  1279.         } else {

  1280.             float temp_real, temp_im;

  1281.             temp_real = phi[0][0][0] * phi[1][1][0] -

  1282.                         phi[0][0][1] * phi[1][1][1] -

  1283.                         phi[0][1][0] * phi[1][0][0];

  1284.             temp_im   = phi[0][0][0] * phi[1][1][1] +

  1285.                         phi[0][0][1] * phi[1][1][0] -

  1286.                         phi[0][1][1] * phi[1][0][0];

  1287. 

  1288.             alpha1[k][0] = temp_real / dk;

  1289.             alpha1[k][1] = temp_im   / dk;

  1290.         }

  1291. 

  1292.         if (!phi[1][0][0]) {

  1293.             alpha0[k][0] = 0;

  1294.             alpha0[k][1] = 0;

  1295.         } else {

  1296.             float temp_real, temp_im;

  1297.             temp_real = phi[0][0][0] + alpha1[k][0] * phi[1][1][0] +

  1298.                                        alpha1[k][1] * phi[1][1][1];

  1299.             temp_im   = phi[0][0][1] + alpha1[k][1] * phi[1][1][0] -

  1300.                                        alpha1[k][0] * phi[1][1][1];

  1301. 

  1302.             alpha0[k][0] = -temp_real / phi[1][0][0];

  1303.             alpha0[k][1] = -temp_im   / phi[1][0][0];

  1304.         }

  1305. 

  1306.         if (alpha1[k][0] * alpha1[k][0] + alpha1[k][1] * alpha1[k][1] >= 16.0f ||

  1307.            alpha0[k][0] * alpha0[k][0] + alpha0[k][1] * alpha0[k][1] >= 16.0f) {

  1308.             alpha1[k][0] = 0;

  1309.             alpha1[k][1] = 0;

  1310.             alpha0[k][0] = 0;

  1311.             alpha0[k][1] = 0;

  1312.         }

  1313.     }

  1314. }

  1315. 

  1316. /// Chirp Factors (14496-3 sp04 p214)

  1317. static void sbr_chirp(SpectralBandReplication *sbr, SBRData *ch_data)

  1318. {

  1319.     int i;

  1320.     float new_bw;

  1321.     static const float bw_tab[] = { 0.0f, 0.75f, 0.9f, 0.98f };

  1322. 

  1323.     for (i = 0; i < sbr->n_q; i++) {

  1324.         if (ch_data->bs_invf_mode[0][i] + ch_data->bs_invf_mode[1][i] == 1) {

  1325.             new_bw = 0.6f;

  1326.         } else

  1327.             new_bw = bw_tab[ch_data->bs_invf_mode[0][i]];

  1328. 

  1329.         if (new_bw < ch_data->bw_array[i]) {

  1330.             new_bw = 0.75f    * new_bw + 0.25f    * ch_data->bw_array[i];

  1331.         } else

  1332.             new_bw = 0.90625f * new_bw + 0.09375f * ch_data->bw_array[i];

  1333.         ch_data->bw_array[i] = new_bw < 0.015625f ? 0.0f : new_bw;

  1334.     }

  1335. }

  1336. 

  1337. /// Generate the subband filtered lowband

  1338. static int sbr_lf_gen(AACContext *ac, SpectralBandReplication *sbr,

  1339.                       float X_low[32][40][2], const float W[2][32][32][2])

  1340. {

  1341.     int i, k;

  1342.     const int t_HFGen = 8;

  1343.     const int i_f = 32;

  1344.     memset(X_low, 0, 32*sizeof(*X_low));

  1345.     for (k = 0; k < sbr->kx[1]; k++) {

  1346.         for (i = t_HFGen; i < i_f + t_HFGen; i++) {

  1347.             X_low[k][i][0] = W[1][i - t_HFGen][k][0];

  1348.             X_low[k][i][1] = W[1][i - t_HFGen][k][1];

  1349.         }

  1350.     }

  1351.     for (k = 0; k < sbr->kx[0]; k++) {

  1352.         for (i = 0; i < t_HFGen; i++) {

  1353.             X_low[k][i][0] = W[0][i + i_f - t_HFGen][k][0];

  1354.             X_low[k][i][1] = W[0][i + i_f - t_HFGen][k][1];

  1355.         }

  1356.     }

  1357.     return 0;

  1358. }

  1359. 

  1360. /// High Frequency Generator (14496-3 sp04 p215)

  1361. static int sbr_hf_gen(AACContext *ac, SpectralBandReplication *sbr,

  1362.                       float X_high[64][40][2], const float X_low[32][40][2],

  1363.                       const float (*alpha0)[2], const float (*alpha1)[2],

  1364.                       const float bw_array[5], const uint8_t *t_env,

  1365.                       int bs_num_env)

  1366. {

  1367.     int i, j, x;

  1368.     int g = 0;

  1369.     int k = sbr->kx[1];

  1370.     for (j = 0; j < sbr->num_patches; j++) {

  1371.         for (x = 0; x < sbr->patch_num_subbands[j]; x++, k++) {

  1372.             float alpha[4];

  1373.             const int p = sbr->patch_start_subband[j] + x;

  1374.             while (g <= sbr->n_q && k >= sbr->f_tablenoise[g])

  1375.                 g++;

  1376.             g--;

  1377. 

  1378.             if (g < 0) {

  1379.                 av_log(ac->avctx, AV_LOG_ERROR,

  1380.                        "ERROR : no subband found for frequency %d\n", k);

  1381.                 return -1;

  1382.             }

  1383. 

  1384.             alpha[0] = alpha1[p][0] * bw_array[g] * bw_array[g];

  1385.             alpha[1] = alpha1[p][1] * bw_array[g] * bw_array[g];

  1386.             alpha[2] = alpha0[p][0] * bw_array[g];

  1387.             alpha[3] = alpha0[p][1] * bw_array[g];

  1388. 

  1389.             for (i = 2 * t_env[0]; i < 2 * t_env[bs_num_env]; i++) {

  1390.                 const int idx = i + ENVELOPE_ADJUSTMENT_OFFSET;

  1391.                 X_high[k][idx][0] =

  1392.                     X_low[p][idx - 2][0] * alpha[0] -

  1393.                     X_low[p][idx - 2][1] * alpha[1] +

  1394.                     X_low[p][idx - 1][0] * alpha[2] -

  1395.                     X_low[p][idx - 1][1] * alpha[3] +

  1396.                     X_low[p][idx][0];

  1397.                 X_high[k][idx][1] =

  1398.                     X_low[p][idx - 2][1] * alpha[0] +

  1399.                     X_low[p][idx - 2][0] * alpha[1] +

  1400.                     X_low[p][idx - 1][1] * alpha[2] +

  1401.                     X_low[p][idx - 1][0] * alpha[3] +

  1402.                     X_low[p][idx][1];

  1403.             }

  1404.         }

  1405.     }

  1406.     if (k < sbr->m[1] + sbr->kx[1])

  1407.         memset(X_high + k, 0, (sbr->m[1] + sbr->kx[1] - k) * sizeof(*X_high));

  1408. 

  1409.     return 0;

  1410. }

  1411. 

  1412. /// Generate the subband filtered lowband

  1413. static int sbr_x_gen(SpectralBandReplication *sbr, float X[2][38][64],

  1414.                      const float X_low[32][40][2], const float Y[2][38][64][2],

  1415.                      int ch)

  1416. {

  1417.     int k, i;

  1418.     const int i_f = 32;

  1419.     const int i_Temp = FFMAX(2*sbr->data[ch].t_env_num_env_old - i_f, 0);

  1420.     memset(X, 0, 2*sizeof(*X));

  1421.     for (k = 0; k < sbr->kx[0]; k++) {

  1422.         for (i = 0; i < i_Temp; i++) {

  1423.             X[0][i][k] = X_low[k][i + ENVELOPE_ADJUSTMENT_OFFSET][0];

  1424.             X[1][i][k] = X_low[k][i + ENVELOPE_ADJUSTMENT_OFFSET][1];

  1425.         }

  1426.     }

  1427.     for (; k < sbr->kx[0] + sbr->m[0]; k++) {

  1428.         for (i = 0; i < i_Temp; i++) {

  1429.             X[0][i][k] = Y[0][i + i_f][k][0];

  1430.             X[1][i][k] = Y[0][i + i_f][k][1];

  1431.         }

  1432.     }

  1433. 

  1434.     for (k = 0; k < sbr->kx[1]; k++) {

  1435.         for (i = i_Temp; i < 38; i++) {

  1436.             X[0][i][k] = X_low[k][i + ENVELOPE_ADJUSTMENT_OFFSET][0];

  1437.             X[1][i][k] = X_low[k][i + ENVELOPE_ADJUSTMENT_OFFSET][1];

  1438.         }

  1439.     }

  1440.     for (; k < sbr->kx[1] + sbr->m[1]; k++) {

  1441.         for (i = i_Temp; i < i_f; i++) {

  1442.             X[0][i][k] = Y[1][i][k][0];

  1443.             X[1][i][k] = Y[1][i][k][1];

  1444.         }

  1445.     }

  1446.     return 0;

  1447. }

  1448. 

  1449. /** High Frequency Adjustment (14496-3 sp04 p217) and Mapping

  1450.  * (14496-3 sp04 p217)

  1451.  */

  1452. static void sbr_mapping(AACContext *ac, SpectralBandReplication *sbr,

  1453.                         SBRData *ch_data, int e_a[2])

  1454. {

  1455.     int e, i, m;

  1456. 

  1457.     memset(ch_data->s_indexmapped[1], 0, 7*sizeof(ch_data->s_indexmapped[1]));

  1458.     for (e = 0; e < ch_data->bs_num_env; e++) {

  1459.         const unsigned int ilim = sbr->n[ch_data->bs_freq_res[e + 1]];

  1460.         uint16_t *table = ch_data->bs_freq_res[e + 1] ? sbr->f_tablehigh : sbr->f_tablelow;

  1461.         int k;

  1462. 

  1463.         av_assert0(sbr->kx[1] <= table[0]);

  1464.         for (i = 0; i < ilim; i++)

  1465.             for (m = table[i]; m < table[i + 1]; m++)

  1466.                 sbr->e_origmapped[e][m - sbr->kx[1]] = ch_data->env_facs[e+1][i];

  1467. 

  1468.         // ch_data->bs_num_noise > 1 => 2 noise floors

  1469.         k = (ch_data->bs_num_noise > 1) && (ch_data->t_env[e] >= ch_data->t_q[1]);

  1470.         for (i = 0; i < sbr->n_q; i++)

  1471.             for (m = sbr->f_tablenoise[i]; m < sbr->f_tablenoise[i + 1]; m++)

  1472.                 sbr->q_mapped[e][m - sbr->kx[1]] = ch_data->noise_facs[k+1][i];

  1473. 

  1474.         for (i = 0; i < sbr->n[1]; i++) {

  1475.             if (ch_data->bs_add_harmonic_flag) {

  1476.                 const unsigned int m_midpoint =

  1477.                     (sbr->f_tablehigh[i] + sbr->f_tablehigh[i + 1]) >> 1;

  1478. 

  1479.                 ch_data->s_indexmapped[e + 1][m_midpoint - sbr->kx[1]] = ch_data->bs_add_harmonic[i] *

  1480.                     (e >= e_a[1] || (ch_data->s_indexmapped[0][m_midpoint - sbr->kx[1]] == 1));

  1481.             }

  1482.         }

  1483. 

  1484.         for (i = 0; i < ilim; i++) {

  1485.             int additional_sinusoid_present = 0;

  1486.             for (m = table[i]; m < table[i + 1]; m++) {

  1487.                 if (ch_data->s_indexmapped[e + 1][m - sbr->kx[1]]) {

  1488.                     additional_sinusoid_present = 1;

  1489.                     break;

  1490.                 }

  1491.             }

  1492.             memset(&sbr->s_mapped[e][table[i] - sbr->kx[1]], additional_sinusoid_present,

  1493.                    (table[i + 1] - table[i]) * sizeof(sbr->s_mapped[e][0]));

  1494.         }

  1495.     }

  1496. 

  1497.     memcpy(ch_data->s_indexmapped[0], ch_data->s_indexmapped[ch_data->bs_num_env], sizeof(ch_data->s_indexmapped[0]));

  1498. }

  1499. 

  1500. /// Estimation of current envelope (14496-3 sp04 p218)

  1501. static void sbr_env_estimate(float (*e_curr)[48], float X_high[64][40][2],

  1502.                              SpectralBandReplication *sbr, SBRData *ch_data)

  1503. {

  1504.     int e, i, m;

  1505. 

  1506.     if (sbr->bs_interpol_freq) {

  1507.         for (e = 0; e < ch_data->bs_num_env; e++) {

  1508.             const float recip_env_size = 0.5f / (ch_data->t_env[e + 1] - ch_data->t_env[e]);

  1509.             int ilb = ch_data->t_env[e]     * 2 + ENVELOPE_ADJUSTMENT_OFFSET;

  1510.             int iub = ch_data->t_env[e + 1] * 2 + ENVELOPE_ADJUSTMENT_OFFSET;

  1511. 

  1512.             for (m = 0; m < sbr->m[1]; m++) {

  1513.                 float sum = 0.0f;

  1514. 

  1515.                 for (i = ilb; i < iub; i++) {

  1516.                     sum += X_high[m + sbr->kx[1]][i][0] * X_high[m + sbr->kx[1]][i][0] +

  1517.                            X_high[m + sbr->kx[1]][i][1] * X_high[m + sbr->kx[1]][i][1];

  1518.                 }

  1519.                 e_curr[e][m] = sum * recip_env_size;

  1520.             }

  1521.         }

  1522.     } else {

  1523.         int k, p;

  1524. 

  1525.         for (e = 0; e < ch_data->bs_num_env; e++) {

  1526.             const int env_size = 2 * (ch_data->t_env[e + 1] - ch_data->t_env[e]);

  1527.             int ilb = ch_data->t_env[e]     * 2 + ENVELOPE_ADJUSTMENT_OFFSET;

  1528.             int iub = ch_data->t_env[e + 1] * 2 + ENVELOPE_ADJUSTMENT_OFFSET;

  1529.             const uint16_t *table = ch_data->bs_freq_res[e + 1] ? sbr->f_tablehigh : sbr->f_tablelow;

  1530. 

  1531.             for (p = 0; p < sbr->n[ch_data->bs_freq_res[e + 1]]; p++) {

  1532.                 float sum = 0.0f;

  1533.                 const int den = env_size * (table[p + 1] - table[p]);

  1534. 

  1535.                 for (k = table[p]; k < table[p + 1]; k++) {

  1536.                     for (i = ilb; i < iub; i++) {

  1537.                         sum += X_high[k][i][0] * X_high[k][i][0] +

  1538.                                X_high[k][i][1] * X_high[k][i][1];

  1539.                     }

  1540.                 }

  1541.                 sum /= den;

  1542.                 for (k = table[p]; k < table[p + 1]; k++) {

  1543.                     e_curr[e][k - sbr->kx[1]] = sum;

  1544.                 }

  1545.             }

  1546.         }

  1547.     }

  1548. }

  1549. 

  1550. /**

  1551.  * Calculation of levels of additional HF signal components (14496-3 sp04 p219)

  1552.  * and Calculation of gain (14496-3 sp04 p219)

  1553.  */

  1554. static void sbr_gain_calc(AACContext *ac, SpectralBandReplication *sbr,

  1555.                           SBRData *ch_data, const int e_a[2])

  1556. {

  1557.     int e, k, m;

  1558.     // max gain limits : -3dB, 0dB, 3dB, inf dB (limiter off)

  1559.     static const float limgain[4] = { 0.70795, 1.0, 1.41254, 10000000000 };

  1560. 

  1561.     for (e = 0; e < ch_data->bs_num_env; e++) {

  1562.         int delta = !((e == e_a[1]) || (e == e_a[0]));

  1563.         for (k = 0; k < sbr->n_lim; k++) {

  1564.             float gain_boost, gain_max;

  1565.             float sum[2] = { 0.0f, 0.0f };

  1566.             for (m = sbr->f_tablelim[k] - sbr->kx[1]; m < sbr->f_tablelim[k + 1] - sbr->kx[1]; m++) {

  1567.                 const float temp = sbr->e_origmapped[e][m] / (1.0f + sbr->q_mapped[e][m]);

  1568.                 sbr->q_m[e][m] = sqrtf(temp * sbr->q_mapped[e][m]);

  1569.                 sbr->s_m[e][m] = sqrtf(temp * ch_data->s_indexmapped[e + 1][m]);

  1570.                 if (!sbr->s_mapped[e][m]) {

  1571.                     sbr->gain[e][m] = sqrtf(sbr->e_origmapped[e][m] /

  1572.                                             ((1.0f + sbr->e_curr[e][m]) *

  1573.                                              (1.0f + sbr->q_mapped[e][m] * delta)));

  1574.                 } else {

  1575.                     sbr->gain[e][m] = sqrtf(sbr->e_origmapped[e][m] * sbr->q_mapped[e][m] /

  1576.                                             ((1.0f + sbr->e_curr[e][m]) *

  1577.                                              (1.0f + sbr->q_mapped[e][m])));

  1578.                 }

  1579.             }

  1580.             for (m = sbr->f_tablelim[k] - sbr->kx[1]; m < sbr->f_tablelim[k + 1] - sbr->kx[1]; m++) {

  1581.                 sum[0] += sbr->e_origmapped[e][m];

  1582.                 sum[1] += sbr->e_curr[e][m];

  1583.             }

  1584.             gain_max = limgain[sbr->bs_limiter_gains] * sqrtf((FLT_EPSILON + sum[0]) / (FLT_EPSILON + sum[1]));

  1585.             gain_max = FFMIN(100000.f, gain_max);

  1586.             for (m = sbr->f_tablelim[k] - sbr->kx[1]; m < sbr->f_tablelim[k + 1] - sbr->kx[1]; m++) {

  1587.                 float q_m_max   = sbr->q_m[e][m] * gain_max / sbr->gain[e][m];

  1588.                 sbr->q_m[e][m]  = FFMIN(sbr->q_m[e][m], q_m_max);

  1589.                 sbr->gain[e][m] = FFMIN(sbr->gain[e][m], gain_max);

  1590.             }

  1591.             sum[0] = sum[1] = 0.0f;

  1592.             for (m = sbr->f_tablelim[k] - sbr->kx[1]; m < sbr->f_tablelim[k + 1] - sbr->kx[1]; m++) {

  1593.                 sum[0] += sbr->e_origmapped[e][m];

  1594.                 sum[1] += sbr->e_curr[e][m] * sbr->gain[e][m] * sbr->gain[e][m]

  1595.                           + sbr->s_m[e][m] * sbr->s_m[e][m]

  1596.                           + (delta && !sbr->s_m[e][m]) * sbr->q_m[e][m] * sbr->q_m[e][m];

  1597.             }

  1598.             gain_boost = sqrtf((FLT_EPSILON + sum[0]) / (FLT_EPSILON + sum[1]));

  1599.             gain_boost = FFMIN(1.584893192f, gain_boost);

  1600.             for (m = sbr->f_tablelim[k] - sbr->kx[1]; m < sbr->f_tablelim[k + 1] - sbr->kx[1]; m++) {

  1601.                 sbr->gain[e][m] *= gain_boost;

  1602.                 sbr->q_m[e][m]  *= gain_boost;

  1603.                 sbr->s_m[e][m]  *= gain_boost;

  1604.             }

  1605.         }

  1606.     }

  1607. }

  1608. 

  1609. /// Assembling HF Signals (14496-3 sp04 p220)

  1610. static void sbr_hf_assemble(float Y[2][38][64][2], const float X_high[64][40][2],

  1611.                             SpectralBandReplication *sbr, SBRData *ch_data,

  1612.                             const int e_a[2])

  1613. {

  1614.     int e, i, j, m;

  1615.     const int h_SL = 4 * !sbr->bs_smoothing_mode;

  1616.     const int kx = sbr->kx[1];

  1617.     const int m_max = sbr->m[1];

  1618.     static const float h_smooth[5] = {

  1619.         0.33333333333333,

  1620.         0.30150283239582,

  1621.         0.21816949906249,

  1622.         0.11516383427084,

  1623.         0.03183050093751,

  1624.     };

  1625.     static const int8_t phi[2][4] = {

  1626.         {  1,  0, -1,  0}, // real

  1627.         {  0,  1,  0, -1}, // imaginary

  1628.     };

  1629.     float (*g_temp)[48] = ch_data->g_temp, (*q_temp)[48] = ch_data->q_temp;

  1630.     int indexnoise = ch_data->f_indexnoise;

  1631.     int indexsine  = ch_data->f_indexsine;

  1632.     memcpy(Y[0], Y[1], sizeof(Y[0]));

  1633. 

  1634.     if (sbr->reset) {

  1635.         for (i = 0; i < h_SL; i++) {

  1636.             memcpy(g_temp[i + 2*ch_data->t_env[0]], sbr->gain[0], m_max * sizeof(sbr->gain[0][0]));

  1637.             memcpy(q_temp[i + 2*ch_data->t_env[0]], sbr->q_m[0],  m_max * sizeof(sbr->q_m[0][0]));

  1638.         }

  1639.     } else if (h_SL) {

  1640.         memcpy(g_temp[2*ch_data->t_env[0]], g_temp[2*ch_data->t_env_num_env_old], 4*sizeof(g_temp[0]));

  1641.         memcpy(q_temp[2*ch_data->t_env[0]], q_temp[2*ch_data->t_env_num_env_old], 4*sizeof(q_temp[0]));

  1642.     }

  1643. 

  1644.     for (e = 0; e < ch_data->bs_num_env; e++) {

  1645.         for (i = 2 * ch_data->t_env[e]; i < 2 * ch_data->t_env[e + 1]; i++) {

  1646.             memcpy(g_temp[h_SL + i], sbr->gain[e], m_max * sizeof(sbr->gain[0][0]));

  1647.             memcpy(q_temp[h_SL + i], sbr->q_m[e],  m_max * sizeof(sbr->q_m[0][0]));

  1648.         }

  1649.     }

  1650. 

  1651.     for (e = 0; e < ch_data->bs_num_env; e++) {

  1652.         for (i = 2 * ch_data->t_env[e]; i < 2 * ch_data->t_env[e + 1]; i++) {

  1653.             int phi_sign = (1 - 2*(kx & 1));

  1654. 

  1655.             if (h_SL && e != e_a[0] && e != e_a[1]) {

  1656.                 for (m = 0; m < m_max; m++) {

  1657.                     const int idx1 = i + h_SL;

  1658.                     float g_filt = 0.0f;

  1659.                     for (j = 0; j <= h_SL; j++)

  1660.                         g_filt += g_temp[idx1 - j][m] * h_smooth[j];

  1661.                     Y[1][i][m + kx][0] =

  1662.                         X_high[m + kx][i + ENVELOPE_ADJUSTMENT_OFFSET][0] * g_filt;

  1663.                     Y[1][i][m + kx][1] =

  1664.                         X_high[m + kx][i + ENVELOPE_ADJUSTMENT_OFFSET][1] * g_filt;

  1665.                 }

  1666.             } else {

  1667.                 for (m = 0; m < m_max; m++) {

  1668.                     const float g_filt = g_temp[i + h_SL][m];

  1669.                     Y[1][i][m + kx][0] =

  1670.                         X_high[m + kx][i + ENVELOPE_ADJUSTMENT_OFFSET][0] * g_filt;

  1671.                     Y[1][i][m + kx][1] =

  1672.                         X_high[m + kx][i + ENVELOPE_ADJUSTMENT_OFFSET][1] * g_filt;

  1673.                 }

  1674.             }

  1675. 

  1676.             if (e != e_a[0] && e != e_a[1]) {

  1677.                 for (m = 0; m < m_max; m++) {

  1678.                     indexnoise = (indexnoise + 1) & 0x1ff;

  1679.                     if (sbr->s_m[e][m]) {

  1680.                         Y[1][i][m + kx][0] +=

  1681.                             sbr->s_m[e][m] * phi[0][indexsine];

  1682.                         Y[1][i][m + kx][1] +=

  1683.                             sbr->s_m[e][m] * (phi[1][indexsine] * phi_sign);

  1684.                     } else {

  1685.                         float q_filt;

  1686.                         if (h_SL) {

  1687.                             const int idx1 = i + h_SL;

  1688.                             q_filt = 0.0f;

  1689.                             for (j = 0; j <= h_SL; j++)

  1690.                                 q_filt += q_temp[idx1 - j][m] * h_smooth[j];

  1691.                         } else {

  1692.                             q_filt = q_temp[i][m];

  1693.                         }

  1694.                         Y[1][i][m + kx][0] +=

  1695.                             q_filt * sbr_noise_table[indexnoise][0];

  1696.                         Y[1][i][m + kx][1] +=

  1697.                             q_filt * sbr_noise_table[indexnoise][1];

  1698.                     }

  1699.                     phi_sign = -phi_sign;

  1700.                 }

  1701.             } else {

  1702.                 indexnoise = (indexnoise + m_max) & 0x1ff;

  1703.                 for (m = 0; m < m_max; m++) {

  1704.                     Y[1][i][m + kx][0] +=

  1705.                         sbr->s_m[e][m] * phi[0][indexsine];

  1706.                     Y[1][i][m + kx][1] +=

  1707.                         sbr->s_m[e][m] * (phi[1][indexsine] * phi_sign);

  1708.                     phi_sign = -phi_sign;

  1709.                 }

  1710.             }

  1711.             indexsine = (indexsine + 1) & 3;

  1712.         }

  1713.     }

  1714.     ch_data->f_indexnoise = indexnoise;

  1715.     ch_data->f_indexsine  = indexsine;

  1716. }

  1717. 

  1718. void ff_sbr_apply(AACContext *ac, SpectralBandReplication *sbr, int id_aac,

  1719.                   float* L, float* R)

  1720. {

  1721.     int downsampled = ac->m4ac.ext_sample_rate < sbr->sample_rate;

  1722.     int ch;

  1723.     int nch = (id_aac == TYPE_CPE) ? 2 : 1;

  1724. 

  1725.     if (sbr->start) {

  1726.         sbr_dequant(sbr, id_aac);

  1727.     }

  1728.     for (ch = 0; ch < nch; ch++) {

  1729.         /* decode channel */

  1730.         sbr_qmf_analysis(&ac->dsp, &sbr->mdct_ana, ch ? R : L, sbr->data[ch].analysis_filterbank_samples,

  1731.                          (float*)sbr->qmf_filter_scratch,

  1732.                          sbr->data[ch].W);

  1733.         sbr_lf_gen(ac, sbr, sbr->X_low, sbr->data[ch].W);

  1734.         if (sbr->start) {

  1735.             sbr_hf_inverse_filter(sbr->alpha0, sbr->alpha1, sbr->X_low, sbr->k[0]);

  1736.             sbr_chirp(sbr, &sbr->data[ch]);

  1737.             sbr_hf_gen(ac, sbr, sbr->X_high, sbr->X_low, sbr->alpha0, sbr->alpha1,

  1738.                        sbr->data[ch].bw_array, sbr->data[ch].t_env,

  1739.                        sbr->data[ch].bs_num_env);

  1740. 

  1741.             // hf_adj

  1742.             sbr_mapping(ac, sbr, &sbr->data[ch], sbr->data[ch].e_a);

  1743.             sbr_env_estimate(sbr->e_curr, sbr->X_high, sbr, &sbr->data[ch]);

  1744.             sbr_gain_calc(ac, sbr, &sbr->data[ch], sbr->data[ch].e_a);

  1745.             sbr_hf_assemble(sbr->data[ch].Y, sbr->X_high, sbr, &sbr->data[ch],

  1746.                             sbr->data[ch].e_a);

  1747.         }

  1748. 

  1749.         /* synthesis */

  1750.         sbr_x_gen(sbr, sbr->X[ch], sbr->X_low, sbr->data[ch].Y, ch);

  1751.     }

  1752. 

  1753.     if (ac->m4ac.ps == 1) {

  1754.         if (sbr->ps.start) {

  1755.             ff_ps_apply(ac->avctx, &sbr->ps, sbr->X[0], sbr->X[1], sbr->kx[1] + sbr->m[1]);

  1756.         } else {

  1757.             memcpy(sbr->X[1], sbr->X[0], sizeof(sbr->X[0]));

  1758.         }

  1759.         nch = 2;

  1760.     }

  1761. 

  1762.     sbr_qmf_synthesis(&ac->dsp, &sbr->mdct, L, sbr->X[0], sbr->qmf_filter_scratch,

  1763.                       sbr->data[0].synthesis_filterbank_samples,

  1764.                       &sbr->data[0].synthesis_filterbank_samples_offset,

  1765.                       downsampled);

  1766.     if (nch == 2)

  1767.         sbr_qmf_synthesis(&ac->dsp, &sbr->mdct, R, sbr->X[1], sbr->qmf_filter_scratch,

  1768.                           sbr->data[1].synthesis_filterbank_samples,

  1769.                           &sbr->data[1].synthesis_filterbank_samples_offset,

  1770.                           downsampled);

  1771. }