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  1. /*
  2.  * The simplest AC-3 encoder
  3.  * Copyright (c) 2000 Fabrice Bellard
  4.  * Copyright (c) 2006-2010 Justin Ruggles <justin.ruggles@gmail.com>
  5.  * Copyright (c) 2006-2010 Prakash Punnoor <prakash@punnoor.de>
  6.  *
  7.  * This file is part of FFmpeg.
  8.  *
  9.  * FFmpeg is free software; you can redistribute it and/or
  10.  * modify it under the terms of the GNU Lesser General Public
  11.  * License as published by the Free Software Foundation; either
  12.  * version 2.1 of the License, or (at your option) any later version.
  13.  *
  14.  * FFmpeg is distributed in the hope that it will be useful,
  15.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17.  * Lesser General Public License for more details.
  18.  *
  19.  * You should have received a copy of the GNU Lesser General Public
  20.  * License along with FFmpeg; if not, write to the Free Software
  21.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  22.  */
  23.  
  24. /**
  25.  * @file
  26.  * The simplest AC-3 encoder.
  27.  */
  28.  
  29. #include <stdint.h>
  30.  
  31. #include "libavutil/attributes.h"
  32. #include "libavutil/avassert.h"
  33. #include "libavutil/avstring.h"
  34. #include "libavutil/channel_layout.h"
  35. #include "libavutil/crc.h"
  36. #include "libavutil/internal.h"
  37. #include "libavutil/opt.h"
  38. #include "avcodec.h"
  39. #include "put_bits.h"
  40. #include "ac3dsp.h"
  41. #include "ac3.h"
  42. #include "fft.h"
  43. #include "ac3enc.h"
  44. #include "eac3enc.h"
  45.  
  46. typedef struct AC3Mant {
  47.     int16_t *qmant1_ptr, *qmant2_ptr, *qmant4_ptr; ///< mantissa pointers for bap=1,2,4
  48.     int mant1_cnt, mant2_cnt, mant4_cnt;    ///< mantissa counts for bap=1,2,4
  49. } AC3Mant;
  50.  
  51. #define CMIXLEV_NUM_OPTIONS 3
  52. static const float cmixlev_options[CMIXLEV_NUM_OPTIONS] = {
  53.     LEVEL_MINUS_3DB, LEVEL_MINUS_4POINT5DB, LEVEL_MINUS_6DB
  54. };
  55.  
  56. #define SURMIXLEV_NUM_OPTIONS 3
  57. static const float surmixlev_options[SURMIXLEV_NUM_OPTIONS] = {
  58.     LEVEL_MINUS_3DB, LEVEL_MINUS_6DB, LEVEL_ZERO
  59. };
  60.  
  61. #define EXTMIXLEV_NUM_OPTIONS 8
  62. static const float extmixlev_options[EXTMIXLEV_NUM_OPTIONS] = {
  63.     LEVEL_PLUS_3DB,  LEVEL_PLUS_1POINT5DB,  LEVEL_ONE,       LEVEL_MINUS_4POINT5DB,
  64.     LEVEL_MINUS_3DB, LEVEL_MINUS_4POINT5DB, LEVEL_MINUS_6DB, LEVEL_ZERO
  65. };
  66.  
  67.  
  68. /**
  69.  * LUT for number of exponent groups.
  70.  * exponent_group_tab[coupling][exponent strategy-1][number of coefficients]
  71.  */
  72. static uint8_t exponent_group_tab[2][3][256];
  73.  
  74.  
  75. /**
  76.  * List of supported channel layouts.
  77.  */
  78. const uint64_t ff_ac3_channel_layouts[19] = {
  79.      AV_CH_LAYOUT_MONO,
  80.      AV_CH_LAYOUT_STEREO,
  81.      AV_CH_LAYOUT_2_1,
  82.      AV_CH_LAYOUT_SURROUND,
  83.      AV_CH_LAYOUT_2_2,
  84.      AV_CH_LAYOUT_QUAD,
  85.      AV_CH_LAYOUT_4POINT0,
  86.      AV_CH_LAYOUT_5POINT0,
  87.      AV_CH_LAYOUT_5POINT0_BACK,
  88.     (AV_CH_LAYOUT_MONO     | AV_CH_LOW_FREQUENCY),
  89.     (AV_CH_LAYOUT_STEREO   | AV_CH_LOW_FREQUENCY),
  90.     (AV_CH_LAYOUT_2_1      | AV_CH_LOW_FREQUENCY),
  91.     (AV_CH_LAYOUT_SURROUND | AV_CH_LOW_FREQUENCY),
  92.     (AV_CH_LAYOUT_2_2      | AV_CH_LOW_FREQUENCY),
  93.     (AV_CH_LAYOUT_QUAD     | AV_CH_LOW_FREQUENCY),
  94.     (AV_CH_LAYOUT_4POINT0  | AV_CH_LOW_FREQUENCY),
  95.      AV_CH_LAYOUT_5POINT1,
  96.      AV_CH_LAYOUT_5POINT1_BACK,
  97.      0
  98. };
  99.  
  100.  
  101. /**
  102.  * LUT to select the bandwidth code based on the bit rate, sample rate, and
  103.  * number of full-bandwidth channels.
  104.  * bandwidth_tab[fbw_channels-1][sample rate code][bit rate code]
  105.  */
  106. static const uint8_t ac3_bandwidth_tab[5][3][19] = {
  107. //      32  40  48  56  64  80  96 112 128 160 192 224 256 320 384 448 512 576 640
  108.  
  109.     { {  0,  0,  0, 12, 16, 32, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48 },
  110.       {  0,  0,  0, 16, 20, 36, 56, 56, 56, 56, 56, 56, 56, 56, 56, 56, 56, 56, 56 },
  111.       {  0,  0,  0, 32, 40, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60 } },
  112.  
  113.     { {  0,  0,  0,  0,  0,  0,  0, 20, 24, 32, 48, 48, 48, 48, 48, 48, 48, 48, 48 },
  114.       {  0,  0,  0,  0,  0,  0,  4, 24, 28, 36, 56, 56, 56, 56, 56, 56, 56, 56, 56 },
  115.       {  0,  0,  0,  0,  0,  0, 20, 44, 52, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60 } },
  116.  
  117.     { {  0,  0,  0,  0,  0,  0,  0,  0,  0, 16, 24, 32, 40, 48, 48, 48, 48, 48, 48 },
  118.       {  0,  0,  0,  0,  0,  0,  0,  0,  4, 20, 28, 36, 44, 56, 56, 56, 56, 56, 56 },
  119.       {  0,  0,  0,  0,  0,  0,  0,  0, 20, 40, 48, 60, 60, 60, 60, 60, 60, 60, 60 } },
  120.  
  121.     { {  0,  0,  0,  0,  0,  0,  0,  0,  0,  0, 12, 24, 32, 48, 48, 48, 48, 48, 48 },
  122.       {  0,  0,  0,  0,  0,  0,  0,  0,  0,  0, 16, 28, 36, 56, 56, 56, 56, 56, 56 },
  123.       {  0,  0,  0,  0,  0,  0,  0,  0,  0,  0, 32, 48, 60, 60, 60, 60, 60, 60, 60 } },
  124.  
  125.     { {  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  8, 20, 32, 40, 48, 48, 48, 48 },
  126.       {  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0, 12, 24, 36, 44, 56, 56, 56, 56 },
  127.       {  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0, 28, 44, 60, 60, 60, 60, 60, 60 } }
  128. };
  129.  
  130.  
  131. /**
  132.  * LUT to select the coupling start band based on the bit rate, sample rate, and
  133.  * number of full-bandwidth channels. -1 = coupling off
  134.  * ac3_coupling_start_tab[channel_mode-2][sample rate code][bit rate code]
  135.  *
  136.  * TODO: more testing for optimal parameters.
  137.  *       multi-channel tests at 44.1kHz and 32kHz.
  138.  */
  139. static const int8_t ac3_coupling_start_tab[6][3][19] = {
  140. //      32  40  48  56  64  80  96 112 128 160 192 224 256 320 384 448 512 576 640
  141.  
  142.     // 2/0
  143.     { {  0,  0,  0,  0,  0,  0,  0,  1,  1,  7,  8, 11, 12, -1, -1, -1, -1, -1, -1 },
  144.       {  0,  0,  0,  0,  0,  0,  1,  3,  5,  7, 10, 12, 13, -1, -1, -1, -1, -1, -1 },
  145.       {  0,  0,  0,  0,  1,  2,  2,  9, 13, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1 } },
  146.  
  147.     // 3/0
  148.     { {  0,  0,  0,  0,  0,  0,  0,  0,  2,  2,  6,  9, 11, 12, 13, -1, -1, -1, -1 },
  149.       {  0,  0,  0,  0,  0,  0,  0,  0,  2,  2,  6,  9, 11, 12, 13, -1, -1, -1, -1 },
  150.       { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 } },
  151.  
  152.     // 2/1 - untested
  153.     { {  0,  0,  0,  0,  0,  0,  0,  0,  2,  2,  6,  9, 11, 12, 13, -1, -1, -1, -1 },
  154.       {  0,  0,  0,  0,  0,  0,  0,  0,  2,  2,  6,  9, 11, 12, 13, -1, -1, -1, -1 },
  155.       { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 } },
  156.  
  157.     // 3/1
  158.     { {  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  3,  2, 10, 11, 11, 12, 12, 14, -1 },
  159.       {  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  3,  2, 10, 11, 11, 12, 12, 14, -1 },
  160.       { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 } },
  161.  
  162.     // 2/2 - untested
  163.     { {  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  3,  2, 10, 11, 11, 12, 12, 14, -1 },
  164.       {  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  3,  2, 10, 11, 11, 12, 12, 14, -1 },
  165.       { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 } },
  166.  
  167.     // 3/2
  168.     { {  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  1,  6,  8, 11, 12, 12, -1, -1 },
  169.       {  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  1,  6,  8, 11, 12, 12, -1, -1 },
  170.       { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 } },
  171. };
  172.  
  173.  
  174. /**
  175.  * Adjust the frame size to make the average bit rate match the target bit rate.
  176.  * This is only needed for 11025, 22050, and 44100 sample rates or any E-AC-3.
  177.  *
  178.  * @param s  AC-3 encoder private context
  179.  */
  180. void ff_ac3_adjust_frame_size(AC3EncodeContext *s)
  181. {
  182.     while (s->bits_written >= s->bit_rate && s->samples_written >= s->sample_rate) {
  183.         s->bits_written    -= s->bit_rate;
  184.         s->samples_written -= s->sample_rate;
  185.     }
  186.     s->frame_size = s->frame_size_min +
  187.                     2 * (s->bits_written * s->sample_rate < s->samples_written * s->bit_rate);
  188.     s->bits_written    += s->frame_size * 8;
  189.     s->samples_written += AC3_BLOCK_SIZE * s->num_blocks;
  190. }
  191.  
  192.  
  193. /**
  194.  * Set the initial coupling strategy parameters prior to coupling analysis.
  195.  *
  196.  * @param s  AC-3 encoder private context
  197.  */
  198. void ff_ac3_compute_coupling_strategy(AC3EncodeContext *s)
  199. {
  200.     int blk, ch;
  201.     int got_cpl_snr;
  202.     int num_cpl_blocks;
  203.  
  204.     /* set coupling use flags for each block/channel */
  205.     /* TODO: turn coupling on/off and adjust start band based on bit usage */
  206.     for (blk = 0; blk < s->num_blocks; blk++) {
  207.         AC3Block *block = &s->blocks[blk];
  208.         for (ch = 1; ch <= s->fbw_channels; ch++)
  209.             block->channel_in_cpl[ch] = s->cpl_on;
  210.     }
  211.  
  212.     /* enable coupling for each block if at least 2 channels have coupling
  213.        enabled for that block */
  214.     got_cpl_snr = 0;
  215.     num_cpl_blocks = 0;
  216.     for (blk = 0; blk < s->num_blocks; blk++) {
  217.         AC3Block *block = &s->blocks[blk];
  218.         block->num_cpl_channels = 0;
  219.         for (ch = 1; ch <= s->fbw_channels; ch++)
  220.             block->num_cpl_channels += block->channel_in_cpl[ch];
  221.         block->cpl_in_use = block->num_cpl_channels > 1;
  222.         num_cpl_blocks += block->cpl_in_use;
  223.         if (!block->cpl_in_use) {
  224.             block->num_cpl_channels = 0;
  225.             for (ch = 1; ch <= s->fbw_channels; ch++)
  226.                 block->channel_in_cpl[ch] = 0;
  227.         }
  228.  
  229.         block->new_cpl_strategy = !blk;
  230.         if (blk) {
  231.             for (ch = 1; ch <= s->fbw_channels; ch++) {
  232.                 if (block->channel_in_cpl[ch] != s->blocks[blk-1].channel_in_cpl[ch]) {
  233.                     block->new_cpl_strategy = 1;
  234.                     break;
  235.                 }
  236.             }
  237.         }
  238.         block->new_cpl_leak = block->new_cpl_strategy;
  239.  
  240.         if (!blk || (block->cpl_in_use && !got_cpl_snr)) {
  241.             block->new_snr_offsets = 1;
  242.             if (block->cpl_in_use)
  243.                 got_cpl_snr = 1;
  244.         } else {
  245.             block->new_snr_offsets = 0;
  246.         }
  247.     }
  248.     if (!num_cpl_blocks)
  249.         s->cpl_on = 0;
  250.  
  251.     /* set bandwidth for each channel */
  252.     for (blk = 0; blk < s->num_blocks; blk++) {
  253.         AC3Block *block = &s->blocks[blk];
  254.         for (ch = 1; ch <= s->fbw_channels; ch++) {
  255.             if (block->channel_in_cpl[ch])
  256.                 block->end_freq[ch] = s->start_freq[CPL_CH];
  257.             else
  258.                 block->end_freq[ch] = s->bandwidth_code * 3 + 73;
  259.         }
  260.     }
  261. }
  262.  
  263.  
  264. /**
  265.  * Apply stereo rematrixing to coefficients based on rematrixing flags.
  266.  *
  267.  * @param s  AC-3 encoder private context
  268.  */
  269. void ff_ac3_apply_rematrixing(AC3EncodeContext *s)
  270. {
  271.     int nb_coefs;
  272.     int blk, bnd, i;
  273.     int start, end;
  274.     uint8_t *flags = NULL;
  275.  
  276.     if (!s->rematrixing_enabled)
  277.         return;
  278.  
  279.     for (blk = 0; blk < s->num_blocks; blk++) {
  280.         AC3Block *block = &s->blocks[blk];
  281.         if (block->new_rematrixing_strategy)
  282.             flags = block->rematrixing_flags;
  283.         nb_coefs = FFMIN(block->end_freq[1], block->end_freq[2]);
  284.         for (bnd = 0; bnd < block->num_rematrixing_bands; bnd++) {
  285.             if (flags[bnd]) {
  286.                 start = ff_ac3_rematrix_band_tab[bnd];
  287.                 end   = FFMIN(nb_coefs, ff_ac3_rematrix_band_tab[bnd+1]);
  288.                 for (i = start; i < end; i++) {
  289.                     int32_t lt = block->fixed_coef[1][i];
  290.                     int32_t rt = block->fixed_coef[2][i];
  291.                     block->fixed_coef[1][i] = (lt + rt) >> 1;
  292.                     block->fixed_coef[2][i] = (lt - rt) >> 1;
  293.                 }
  294.             }
  295.         }
  296.     }
  297. }
  298.  
  299.  
  300. /*
  301.  * Initialize exponent tables.
  302.  */
  303. static av_cold void exponent_init(AC3EncodeContext *s)
  304. {
  305.     int expstr, i, grpsize;
  306.  
  307.     for (expstr = EXP_D15-1; expstr <= EXP_D45-1; expstr++) {
  308.         grpsize = 3 << expstr;
  309.         for (i = 12; i < 256; i++) {
  310.             exponent_group_tab[0][expstr][i] = (i + grpsize - 4) / grpsize;
  311.             exponent_group_tab[1][expstr][i] = (i              ) / grpsize;
  312.         }
  313.     }
  314.     /* LFE */
  315.     exponent_group_tab[0][0][7] = 2;
  316.  
  317.     if (CONFIG_EAC3_ENCODER && s->eac3)
  318.         ff_eac3_exponent_init();
  319. }
  320.  
  321.  
  322. /*
  323.  * Extract exponents from the MDCT coefficients.
  324.  */
  325. static void extract_exponents(AC3EncodeContext *s)
  326. {
  327.     int ch        = !s->cpl_on;
  328.     int chan_size = AC3_MAX_COEFS * s->num_blocks * (s->channels - ch + 1);
  329.     AC3Block *block = &s->blocks[0];
  330.  
  331.     s->ac3dsp.extract_exponents(block->exp[ch], block->fixed_coef[ch], chan_size);
  332. }
  333.  
  334.  
  335. /**
  336.  * Exponent Difference Threshold.
  337.  * New exponents are sent if their SAD exceed this number.
  338.  */
  339. #define EXP_DIFF_THRESHOLD 500
  340.  
  341. /**
  342.  * Table used to select exponent strategy based on exponent reuse block interval.
  343.  */
  344. static const uint8_t exp_strategy_reuse_tab[4][6] = {
  345.     { EXP_D15, EXP_D15, EXP_D15, EXP_D15, EXP_D15, EXP_D15 },
  346.     { EXP_D15, EXP_D15, EXP_D15, EXP_D15, EXP_D15, EXP_D15 },
  347.     { EXP_D25, EXP_D25, EXP_D15, EXP_D15, EXP_D15, EXP_D15 },
  348.     { EXP_D45, EXP_D25, EXP_D25, EXP_D15, EXP_D15, EXP_D15 }
  349. };
  350.  
  351. /*
  352.  * Calculate exponent strategies for all channels.
  353.  * Array arrangement is reversed to simplify the per-channel calculation.
  354.  */
  355. static void compute_exp_strategy(AC3EncodeContext *s)
  356. {
  357.     int ch, blk, blk1;
  358.  
  359.     for (ch = !s->cpl_on; ch <= s->fbw_channels; ch++) {
  360.         uint8_t *exp_strategy = s->exp_strategy[ch];
  361.         uint8_t *exp          = s->blocks[0].exp[ch];
  362.         int exp_diff;
  363.  
  364.         /* estimate if the exponent variation & decide if they should be
  365.            reused in the next frame */
  366.         exp_strategy[0] = EXP_NEW;
  367.         exp += AC3_MAX_COEFS;
  368.         for (blk = 1; blk < s->num_blocks; blk++, exp += AC3_MAX_COEFS) {
  369.             if (ch == CPL_CH) {
  370.                 if (!s->blocks[blk-1].cpl_in_use) {
  371.                     exp_strategy[blk] = EXP_NEW;
  372.                     continue;
  373.                 } else if (!s->blocks[blk].cpl_in_use) {
  374.                     exp_strategy[blk] = EXP_REUSE;
  375.                     continue;
  376.                 }
  377.             } else if (s->blocks[blk].channel_in_cpl[ch] != s->blocks[blk-1].channel_in_cpl[ch]) {
  378.                 exp_strategy[blk] = EXP_NEW;
  379.                 continue;
  380.             }
  381.             exp_diff = s->dsp.sad[0](NULL, exp, exp - AC3_MAX_COEFS, 16, 16);
  382.             exp_strategy[blk] = EXP_REUSE;
  383.             if (ch == CPL_CH && exp_diff > (EXP_DIFF_THRESHOLD * (s->blocks[blk].end_freq[ch] - s->start_freq[ch]) / AC3_MAX_COEFS))
  384.                 exp_strategy[blk] = EXP_NEW;
  385.             else if (ch > CPL_CH && exp_diff > EXP_DIFF_THRESHOLD)
  386.                 exp_strategy[blk] = EXP_NEW;
  387.         }
  388.  
  389.         /* now select the encoding strategy type : if exponents are often
  390.            recoded, we use a coarse encoding */
  391.         blk = 0;
  392.         while (blk < s->num_blocks) {
  393.             blk1 = blk + 1;
  394.             while (blk1 < s->num_blocks && exp_strategy[blk1] == EXP_REUSE)
  395.                 blk1++;
  396.             exp_strategy[blk] = exp_strategy_reuse_tab[s->num_blks_code][blk1-blk-1];
  397.             blk = blk1;
  398.         }
  399.     }
  400.     if (s->lfe_on) {
  401.         ch = s->lfe_channel;
  402.         s->exp_strategy[ch][0] = EXP_D15;
  403.         for (blk = 1; blk < s->num_blocks; blk++)
  404.             s->exp_strategy[ch][blk] = EXP_REUSE;
  405.     }
  406.  
  407.     /* for E-AC-3, determine frame exponent strategy */
  408.     if (CONFIG_EAC3_ENCODER && s->eac3)
  409.         ff_eac3_get_frame_exp_strategy(s);
  410. }
  411.  
  412.  
  413. /**
  414.  * Update the exponents so that they are the ones the decoder will decode.
  415.  *
  416.  * @param[in,out] exp   array of exponents for 1 block in 1 channel
  417.  * @param nb_exps       number of exponents in active bandwidth
  418.  * @param exp_strategy  exponent strategy for the block
  419.  * @param cpl           indicates if the block is in the coupling channel
  420.  */
  421. static void encode_exponents_blk_ch(uint8_t *exp, int nb_exps, int exp_strategy,
  422.                                     int cpl)
  423. {
  424.     int nb_groups, i, k;
  425.  
  426.     nb_groups = exponent_group_tab[cpl][exp_strategy-1][nb_exps] * 3;
  427.  
  428.     /* for each group, compute the minimum exponent */
  429.     switch(exp_strategy) {
  430.     case EXP_D25:
  431.         for (i = 1, k = 1-cpl; i <= nb_groups; i++) {
  432.             uint8_t exp_min = exp[k];
  433.             if (exp[k+1] < exp_min)
  434.                 exp_min = exp[k+1];
  435.             exp[i-cpl] = exp_min;
  436.             k += 2;
  437.         }
  438.         break;
  439.     case EXP_D45:
  440.         for (i = 1, k = 1-cpl; i <= nb_groups; i++) {
  441.             uint8_t exp_min = exp[k];
  442.             if (exp[k+1] < exp_min)
  443.                 exp_min = exp[k+1];
  444.             if (exp[k+2] < exp_min)
  445.                 exp_min = exp[k+2];
  446.             if (exp[k+3] < exp_min)
  447.                 exp_min = exp[k+3];
  448.             exp[i-cpl] = exp_min;
  449.             k += 4;
  450.         }
  451.         break;
  452.     }
  453.  
  454.     /* constraint for DC exponent */
  455.     if (!cpl && exp[0] > 15)
  456.         exp[0] = 15;
  457.  
  458.     /* decrease the delta between each groups to within 2 so that they can be
  459.        differentially encoded */
  460.     for (i = 1; i <= nb_groups; i++)
  461.         exp[i] = FFMIN(exp[i], exp[i-1] + 2);
  462.     i--;
  463.     while (--i >= 0)
  464.         exp[i] = FFMIN(exp[i], exp[i+1] + 2);
  465.  
  466.     if (cpl)
  467.         exp[-1] = exp[0] & ~1;
  468.  
  469.     /* now we have the exponent values the decoder will see */
  470.     switch (exp_strategy) {
  471.     case EXP_D25:
  472.         for (i = nb_groups, k = (nb_groups * 2)-cpl; i > 0; i--) {
  473.             uint8_t exp1 = exp[i-cpl];
  474.             exp[k--] = exp1;
  475.             exp[k--] = exp1;
  476.         }
  477.         break;
  478.     case EXP_D45:
  479.         for (i = nb_groups, k = (nb_groups * 4)-cpl; i > 0; i--) {
  480.             exp[k] = exp[k-1] = exp[k-2] = exp[k-3] = exp[i-cpl];
  481.             k -= 4;
  482.         }
  483.         break;
  484.     }
  485. }
  486.  
  487.  
  488. /*
  489.  * Encode exponents from original extracted form to what the decoder will see.
  490.  * This copies and groups exponents based on exponent strategy and reduces
  491.  * deltas between adjacent exponent groups so that they can be differentially
  492.  * encoded.
  493.  */
  494. static void encode_exponents(AC3EncodeContext *s)
  495. {
  496.     int blk, blk1, ch, cpl;
  497.     uint8_t *exp, *exp_strategy;
  498.     int nb_coefs, num_reuse_blocks;
  499.  
  500.     for (ch = !s->cpl_on; ch <= s->channels; ch++) {
  501.         exp          = s->blocks[0].exp[ch] + s->start_freq[ch];
  502.         exp_strategy = s->exp_strategy[ch];
  503.  
  504.         cpl = (ch == CPL_CH);
  505.         blk = 0;
  506.         while (blk < s->num_blocks) {
  507.             AC3Block *block = &s->blocks[blk];
  508.             if (cpl && !block->cpl_in_use) {
  509.                 exp += AC3_MAX_COEFS;
  510.                 blk++;
  511.                 continue;
  512.             }
  513.             nb_coefs = block->end_freq[ch] - s->start_freq[ch];
  514.             blk1 = blk + 1;
  515.  
  516.             /* count the number of EXP_REUSE blocks after the current block
  517.                and set exponent reference block numbers */
  518.             s->exp_ref_block[ch][blk] = blk;
  519.             while (blk1 < s->num_blocks && exp_strategy[blk1] == EXP_REUSE) {
  520.                 s->exp_ref_block[ch][blk1] = blk;
  521.                 blk1++;
  522.             }
  523.             num_reuse_blocks = blk1 - blk - 1;
  524.  
  525.             /* for the EXP_REUSE case we select the min of the exponents */
  526.             s->ac3dsp.ac3_exponent_min(exp-s->start_freq[ch], num_reuse_blocks,
  527.                                        AC3_MAX_COEFS);
  528.  
  529.             encode_exponents_blk_ch(exp, nb_coefs, exp_strategy[blk], cpl);
  530.  
  531.             exp += AC3_MAX_COEFS * (num_reuse_blocks + 1);
  532.             blk = blk1;
  533.         }
  534.     }
  535.  
  536.     /* reference block numbers have been changed, so reset ref_bap_set */
  537.     s->ref_bap_set = 0;
  538. }
  539.  
  540.  
  541. /*
  542.  * Count exponent bits based on bandwidth, coupling, and exponent strategies.
  543.  */
  544. static int count_exponent_bits(AC3EncodeContext *s)
  545. {
  546.     int blk, ch;
  547.     int nb_groups, bit_count;
  548.  
  549.     bit_count = 0;
  550.     for (blk = 0; blk < s->num_blocks; blk++) {
  551.         AC3Block *block = &s->blocks[blk];
  552.         for (ch = !block->cpl_in_use; ch <= s->channels; ch++) {
  553.             int exp_strategy = s->exp_strategy[ch][blk];
  554.             int cpl          = (ch == CPL_CH);
  555.             int nb_coefs     = block->end_freq[ch] - s->start_freq[ch];
  556.  
  557.             if (exp_strategy == EXP_REUSE)
  558.                 continue;
  559.  
  560.             nb_groups = exponent_group_tab[cpl][exp_strategy-1][nb_coefs];
  561.             bit_count += 4 + (nb_groups * 7);
  562.         }
  563.     }
  564.  
  565.     return bit_count;
  566. }
  567.  
  568.  
  569. /**
  570.  * Group exponents.
  571.  * 3 delta-encoded exponents are in each 7-bit group. The number of groups
  572.  * varies depending on exponent strategy and bandwidth.
  573.  *
  574.  * @param s  AC-3 encoder private context
  575.  */
  576. void ff_ac3_group_exponents(AC3EncodeContext *s)
  577. {
  578.     int blk, ch, i, cpl;
  579.     int group_size, nb_groups;
  580.     uint8_t *p;
  581.     int delta0, delta1, delta2;
  582.     int exp0, exp1;
  583.  
  584.     for (blk = 0; blk < s->num_blocks; blk++) {
  585.         AC3Block *block = &s->blocks[blk];
  586.         for (ch = !block->cpl_in_use; ch <= s->channels; ch++) {
  587.             int exp_strategy = s->exp_strategy[ch][blk];
  588.             if (exp_strategy == EXP_REUSE)
  589.                 continue;
  590.             cpl = (ch == CPL_CH);
  591.             group_size = exp_strategy + (exp_strategy == EXP_D45);
  592.             nb_groups = exponent_group_tab[cpl][exp_strategy-1][block->end_freq[ch]-s->start_freq[ch]];
  593.             p = block->exp[ch] + s->start_freq[ch] - cpl;
  594.  
  595.             /* DC exponent */
  596.             exp1 = *p++;
  597.             block->grouped_exp[ch][0] = exp1;
  598.  
  599.             /* remaining exponents are delta encoded */
  600.             for (i = 1; i <= nb_groups; i++) {
  601.                 /* merge three delta in one code */
  602.                 exp0   = exp1;
  603.                 exp1   = p[0];
  604.                 p     += group_size;
  605.                 delta0 = exp1 - exp0 + 2;
  606.                 av_assert2(delta0 >= 0 && delta0 <= 4);
  607.  
  608.                 exp0   = exp1;
  609.                 exp1   = p[0];
  610.                 p     += group_size;
  611.                 delta1 = exp1 - exp0 + 2;
  612.                 av_assert2(delta1 >= 0 && delta1 <= 4);
  613.  
  614.                 exp0   = exp1;
  615.                 exp1   = p[0];
  616.                 p     += group_size;
  617.                 delta2 = exp1 - exp0 + 2;
  618.                 av_assert2(delta2 >= 0 && delta2 <= 4);
  619.  
  620.                 block->grouped_exp[ch][i] = ((delta0 * 5 + delta1) * 5) + delta2;
  621.             }
  622.         }
  623.     }
  624. }
  625.  
  626.  
  627. /**
  628.  * Calculate final exponents from the supplied MDCT coefficients and exponent shift.
  629.  * Extract exponents from MDCT coefficients, calculate exponent strategies,
  630.  * and encode final exponents.
  631.  *
  632.  * @param s  AC-3 encoder private context
  633.  */
  634. void ff_ac3_process_exponents(AC3EncodeContext *s)
  635. {
  636.     extract_exponents(s);
  637.  
  638.     compute_exp_strategy(s);
  639.  
  640.     encode_exponents(s);
  641.  
  642.     emms_c();
  643. }
  644.  
  645.  
  646. /*
  647.  * Count frame bits that are based solely on fixed parameters.
  648.  * This only has to be run once when the encoder is initialized.
  649.  */
  650. static void count_frame_bits_fixed(AC3EncodeContext *s)
  651. {
  652.     static const int frame_bits_inc[8] = { 0, 0, 2, 2, 2, 4, 2, 4 };
  653.     int blk;
  654.     int frame_bits;
  655.  
  656.     /* assumptions:
  657.      *   no dynamic range codes
  658.      *   bit allocation parameters do not change between blocks
  659.      *   no delta bit allocation
  660.      *   no skipped data
  661.      *   no auxiliary data
  662.      *   no E-AC-3 metadata
  663.      */
  664.  
  665.     /* header */
  666.     frame_bits = 16; /* sync info */
  667.     if (s->eac3) {
  668.         /* bitstream info header */
  669.         frame_bits += 35;
  670.         frame_bits += 1 + 1;
  671.         if (s->num_blocks != 0x6)
  672.             frame_bits++;
  673.         frame_bits++;
  674.         /* audio frame header */
  675.         if (s->num_blocks == 6)
  676.             frame_bits += 2;
  677.         frame_bits += 10;
  678.         /* exponent strategy */
  679.         if (s->use_frame_exp_strategy)
  680.             frame_bits += 5 * s->fbw_channels;
  681.         else
  682.             frame_bits += s->num_blocks * 2 * s->fbw_channels;
  683.         if (s->lfe_on)
  684.             frame_bits += s->num_blocks;
  685.         /* converter exponent strategy */
  686.         if (s->num_blks_code != 0x3)
  687.             frame_bits++;
  688.         else
  689.             frame_bits += s->fbw_channels * 5;
  690.         /* snr offsets */
  691.         frame_bits += 10;
  692.         /* block start info */
  693.         if (s->num_blocks != 1)
  694.             frame_bits++;
  695.     } else {
  696.         frame_bits += 49;
  697.         frame_bits += frame_bits_inc[s->channel_mode];
  698.     }
  699.  
  700.     /* audio blocks */
  701.     for (blk = 0; blk < s->num_blocks; blk++) {
  702.         if (!s->eac3) {
  703.             /* block switch flags */
  704.             frame_bits += s->fbw_channels;
  705.  
  706.             /* dither flags */
  707.             frame_bits += s->fbw_channels;
  708.         }
  709.  
  710.         /* dynamic range */
  711.         frame_bits++;
  712.  
  713.         /* spectral extension */
  714.         if (s->eac3)
  715.             frame_bits++;
  716.  
  717.         if (!s->eac3) {
  718.             /* exponent strategy */
  719.             frame_bits += 2 * s->fbw_channels;
  720.             if (s->lfe_on)
  721.                 frame_bits++;
  722.  
  723.             /* bit allocation params */
  724.             frame_bits++;
  725.             if (!blk)
  726.                 frame_bits += 2 + 2 + 2 + 2 + 3;
  727.         }
  728.  
  729.         /* converter snr offset */
  730.         if (s->eac3)
  731.             frame_bits++;
  732.  
  733.         if (!s->eac3) {
  734.             /* delta bit allocation */
  735.             frame_bits++;
  736.  
  737.             /* skipped data */
  738.             frame_bits++;
  739.         }
  740.     }
  741.  
  742.     /* auxiliary data */
  743.     frame_bits++;
  744.  
  745.     /* CRC */
  746.     frame_bits += 1 + 16;
  747.  
  748.     s->frame_bits_fixed = frame_bits;
  749. }
  750.  
  751.  
  752. /*
  753.  * Initialize bit allocation.
  754.  * Set default parameter codes and calculate parameter values.
  755.  */
  756. static av_cold void bit_alloc_init(AC3EncodeContext *s)
  757. {
  758.     int ch;
  759.  
  760.     /* init default parameters */
  761.     s->slow_decay_code = 2;
  762.     s->fast_decay_code = 1;
  763.     s->slow_gain_code  = 1;
  764.     s->db_per_bit_code = s->eac3 ? 2 : 3;
  765.     s->floor_code      = 7;
  766.     for (ch = 0; ch <= s->channels; ch++)
  767.         s->fast_gain_code[ch] = 4;
  768.  
  769.     /* initial snr offset */
  770.     s->coarse_snr_offset = 40;
  771.  
  772.     /* compute real values */
  773.     /* currently none of these values change during encoding, so we can just
  774.        set them once at initialization */
  775.     s->bit_alloc.slow_decay = ff_ac3_slow_decay_tab[s->slow_decay_code] >> s->bit_alloc.sr_shift;
  776.     s->bit_alloc.fast_decay = ff_ac3_fast_decay_tab[s->fast_decay_code] >> s->bit_alloc.sr_shift;
  777.     s->bit_alloc.slow_gain  = ff_ac3_slow_gain_tab[s->slow_gain_code];
  778.     s->bit_alloc.db_per_bit = ff_ac3_db_per_bit_tab[s->db_per_bit_code];
  779.     s->bit_alloc.floor      = ff_ac3_floor_tab[s->floor_code];
  780.     s->bit_alloc.cpl_fast_leak = 0;
  781.     s->bit_alloc.cpl_slow_leak = 0;
  782.  
  783.     count_frame_bits_fixed(s);
  784. }
  785.  
  786.  
  787. /*
  788.  * Count the bits used to encode the frame, minus exponents and mantissas.
  789.  * Bits based on fixed parameters have already been counted, so now we just
  790.  * have to add the bits based on parameters that change during encoding.
  791.  */
  792. static void count_frame_bits(AC3EncodeContext *s)
  793. {
  794.     AC3EncOptions *opt = &s->options;
  795.     int blk, ch;
  796.     int frame_bits = 0;
  797.  
  798.     /* header */
  799.     if (s->eac3) {
  800.         if (opt->eac3_mixing_metadata) {
  801.             if (s->channel_mode > AC3_CHMODE_STEREO)
  802.                 frame_bits += 2;
  803.             if (s->has_center)
  804.                 frame_bits += 6;
  805.             if (s->has_surround)
  806.                 frame_bits += 6;
  807.             frame_bits += s->lfe_on;
  808.             frame_bits += 1 + 1 + 2;
  809.             if (s->channel_mode < AC3_CHMODE_STEREO)
  810.                 frame_bits++;
  811.             frame_bits++;
  812.         }
  813.         if (opt->eac3_info_metadata) {
  814.             frame_bits += 3 + 1 + 1;
  815.             if (s->channel_mode == AC3_CHMODE_STEREO)
  816.                 frame_bits += 2 + 2;
  817.             if (s->channel_mode >= AC3_CHMODE_2F2R)
  818.                 frame_bits += 2;
  819.             frame_bits++;
  820.             if (opt->audio_production_info)
  821.                 frame_bits += 5 + 2 + 1;
  822.             frame_bits++;
  823.         }
  824.         /* coupling */
  825.         if (s->channel_mode > AC3_CHMODE_MONO) {
  826.             frame_bits++;
  827.             for (blk = 1; blk < s->num_blocks; blk++) {
  828.                 AC3Block *block = &s->blocks[blk];
  829.                 frame_bits++;
  830.                 if (block->new_cpl_strategy)
  831.                     frame_bits++;
  832.             }
  833.         }
  834.         /* coupling exponent strategy */
  835.         if (s->cpl_on) {
  836.             if (s->use_frame_exp_strategy) {
  837.                 frame_bits += 5 * s->cpl_on;
  838.             } else {
  839.                 for (blk = 0; blk < s->num_blocks; blk++)
  840.                     frame_bits += 2 * s->blocks[blk].cpl_in_use;
  841.             }
  842.         }
  843.     } else {
  844.         if (opt->audio_production_info)
  845.             frame_bits += 7;
  846.         if (s->bitstream_id == 6) {
  847.             if (opt->extended_bsi_1)
  848.                 frame_bits += 14;
  849.             if (opt->extended_bsi_2)
  850.                 frame_bits += 14;
  851.         }
  852.     }
  853.  
  854.     /* audio blocks */
  855.     for (blk = 0; blk < s->num_blocks; blk++) {
  856.         AC3Block *block = &s->blocks[blk];
  857.  
  858.         /* coupling strategy */
  859.         if (!s->eac3)
  860.             frame_bits++;
  861.         if (block->new_cpl_strategy) {
  862.             if (!s->eac3)
  863.                 frame_bits++;
  864.             if (block->cpl_in_use) {
  865.                 if (s->eac3)
  866.                     frame_bits++;
  867.                 if (!s->eac3 || s->channel_mode != AC3_CHMODE_STEREO)
  868.                     frame_bits += s->fbw_channels;
  869.                 if (s->channel_mode == AC3_CHMODE_STEREO)
  870.                     frame_bits++;
  871.                 frame_bits += 4 + 4;
  872.                 if (s->eac3)
  873.                     frame_bits++;
  874.                 else
  875.                     frame_bits += s->num_cpl_subbands - 1;
  876.             }
  877.         }
  878.  
  879.         /* coupling coordinates */
  880.         if (block->cpl_in_use) {
  881.             for (ch = 1; ch <= s->fbw_channels; ch++) {
  882.                 if (block->channel_in_cpl[ch]) {
  883.                     if (!s->eac3 || block->new_cpl_coords[ch] != 2)
  884.                         frame_bits++;
  885.                     if (block->new_cpl_coords[ch]) {
  886.                         frame_bits += 2;
  887.                         frame_bits += (4 + 4) * s->num_cpl_bands;
  888.                     }
  889.                 }
  890.             }
  891.         }
  892.  
  893.         /* stereo rematrixing */
  894.         if (s->channel_mode == AC3_CHMODE_STEREO) {
  895.             if (!s->eac3 || blk > 0)
  896.                 frame_bits++;
  897.             if (s->blocks[blk].new_rematrixing_strategy)
  898.                 frame_bits += block->num_rematrixing_bands;
  899.         }
  900.  
  901.         /* bandwidth codes & gain range */
  902.         for (ch = 1; ch <= s->fbw_channels; ch++) {
  903.             if (s->exp_strategy[ch][blk] != EXP_REUSE) {
  904.                 if (!block->channel_in_cpl[ch])
  905.                     frame_bits += 6;
  906.                 frame_bits += 2;
  907.             }
  908.         }
  909.  
  910.         /* coupling exponent strategy */
  911.         if (!s->eac3 && block->cpl_in_use)
  912.             frame_bits += 2;
  913.  
  914.         /* snr offsets and fast gain codes */
  915.         if (!s->eac3) {
  916.             frame_bits++;
  917.             if (block->new_snr_offsets)
  918.                 frame_bits += 6 + (s->channels + block->cpl_in_use) * (4 + 3);
  919.         }
  920.  
  921.         /* coupling leak info */
  922.         if (block->cpl_in_use) {
  923.             if (!s->eac3 || block->new_cpl_leak != 2)
  924.                 frame_bits++;
  925.             if (block->new_cpl_leak)
  926.                 frame_bits += 3 + 3;
  927.         }
  928.     }
  929.  
  930.     s->frame_bits = s->frame_bits_fixed + frame_bits;
  931. }
  932.  
  933.  
  934. /*
  935.  * Calculate masking curve based on the final exponents.
  936.  * Also calculate the power spectral densities to use in future calculations.
  937.  */
  938. static void bit_alloc_masking(AC3EncodeContext *s)
  939. {
  940.     int blk, ch;
  941.  
  942.     for (blk = 0; blk < s->num_blocks; blk++) {
  943.         AC3Block *block = &s->blocks[blk];
  944.         for (ch = !block->cpl_in_use; ch <= s->channels; ch++) {
  945.             /* We only need psd and mask for calculating bap.
  946.                Since we currently do not calculate bap when exponent
  947.                strategy is EXP_REUSE we do not need to calculate psd or mask. */
  948.             if (s->exp_strategy[ch][blk] != EXP_REUSE) {
  949.                 ff_ac3_bit_alloc_calc_psd(block->exp[ch], s->start_freq[ch],
  950.                                           block->end_freq[ch], block->psd[ch],
  951.                                           block->band_psd[ch]);
  952.                 ff_ac3_bit_alloc_calc_mask(&s->bit_alloc, block->band_psd[ch],
  953.                                            s->start_freq[ch], block->end_freq[ch],
  954.                                            ff_ac3_fast_gain_tab[s->fast_gain_code[ch]],
  955.                                            ch == s->lfe_channel,
  956.                                            DBA_NONE, 0, NULL, NULL, NULL,
  957.                                            block->mask[ch]);
  958.             }
  959.         }
  960.     }
  961. }
  962.  
  963.  
  964. /*
  965.  * Ensure that bap for each block and channel point to the current bap_buffer.
  966.  * They may have been switched during the bit allocation search.
  967.  */
  968. static void reset_block_bap(AC3EncodeContext *s)
  969. {
  970.     int blk, ch;
  971.     uint8_t *ref_bap;
  972.  
  973.     if (s->ref_bap[0][0] == s->bap_buffer && s->ref_bap_set)
  974.         return;
  975.  
  976.     ref_bap = s->bap_buffer;
  977.     for (ch = 0; ch <= s->channels; ch++) {
  978.         for (blk = 0; blk < s->num_blocks; blk++)
  979.             s->ref_bap[ch][blk] = ref_bap + AC3_MAX_COEFS * s->exp_ref_block[ch][blk];
  980.         ref_bap += AC3_MAX_COEFS * s->num_blocks;
  981.     }
  982.     s->ref_bap_set = 1;
  983. }
  984.  
  985.  
  986. /**
  987.  * Initialize mantissa counts.
  988.  * These are set so that they are padded to the next whole group size when bits
  989.  * are counted in compute_mantissa_size.
  990.  *
  991.  * @param[in,out] mant_cnt  running counts for each bap value for each block
  992.  */
  993. static void count_mantissa_bits_init(uint16_t mant_cnt[AC3_MAX_BLOCKS][16])
  994. {
  995.     int blk;
  996.  
  997.     for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
  998.         memset(mant_cnt[blk], 0, sizeof(mant_cnt[blk]));
  999.         mant_cnt[blk][1] = mant_cnt[blk][2] = 2;
  1000.         mant_cnt[blk][4] = 1;
  1001.     }
  1002. }
  1003.  
  1004.  
  1005. /**
  1006.  * Update mantissa bit counts for all blocks in 1 channel in a given bandwidth
  1007.  * range.
  1008.  *
  1009.  * @param s                 AC-3 encoder private context
  1010.  * @param ch                channel index
  1011.  * @param[in,out] mant_cnt  running counts for each bap value for each block
  1012.  * @param start             starting coefficient bin
  1013.  * @param end               ending coefficient bin
  1014.  */
  1015. static void count_mantissa_bits_update_ch(AC3EncodeContext *s, int ch,
  1016.                                           uint16_t mant_cnt[AC3_MAX_BLOCKS][16],
  1017.                                           int start, int end)
  1018. {
  1019.     int blk;
  1020.  
  1021.     for (blk = 0; blk < s->num_blocks; blk++) {
  1022.         AC3Block *block = &s->blocks[blk];
  1023.         if (ch == CPL_CH && !block->cpl_in_use)
  1024.             continue;
  1025.         s->ac3dsp.update_bap_counts(mant_cnt[blk],
  1026.                                     s->ref_bap[ch][blk] + start,
  1027.                                     FFMIN(end, block->end_freq[ch]) - start);
  1028.     }
  1029. }
  1030.  
  1031.  
  1032. /*
  1033.  * Count the number of mantissa bits in the frame based on the bap values.
  1034.  */
  1035. static int count_mantissa_bits(AC3EncodeContext *s)
  1036. {
  1037.     int ch, max_end_freq;
  1038.     LOCAL_ALIGNED_16(uint16_t, mant_cnt, [AC3_MAX_BLOCKS], [16]);
  1039.  
  1040.     count_mantissa_bits_init(mant_cnt);
  1041.  
  1042.     max_end_freq = s->bandwidth_code * 3 + 73;
  1043.     for (ch = !s->cpl_enabled; ch <= s->channels; ch++)
  1044.         count_mantissa_bits_update_ch(s, ch, mant_cnt, s->start_freq[ch],
  1045.                                       max_end_freq);
  1046.  
  1047.     return s->ac3dsp.compute_mantissa_size(mant_cnt);
  1048. }
  1049.  
  1050.  
  1051. /**
  1052.  * Run the bit allocation with a given SNR offset.
  1053.  * This calculates the bit allocation pointers that will be used to determine
  1054.  * the quantization of each mantissa.
  1055.  *
  1056.  * @param s           AC-3 encoder private context
  1057.  * @param snr_offset  SNR offset, 0 to 1023
  1058.  * @return the number of bits needed for mantissas if the given SNR offset is
  1059.  *         is used.
  1060.  */
  1061. static int bit_alloc(AC3EncodeContext *s, int snr_offset)
  1062. {
  1063.     int blk, ch;
  1064.  
  1065.     snr_offset = (snr_offset - 240) << 2;
  1066.  
  1067.     reset_block_bap(s);
  1068.     for (blk = 0; blk < s->num_blocks; blk++) {
  1069.         AC3Block *block = &s->blocks[blk];
  1070.  
  1071.         for (ch = !block->cpl_in_use; ch <= s->channels; ch++) {
  1072.             /* Currently the only bit allocation parameters which vary across
  1073.                blocks within a frame are the exponent values.  We can take
  1074.                advantage of that by reusing the bit allocation pointers
  1075.                whenever we reuse exponents. */
  1076.             if (s->exp_strategy[ch][blk] != EXP_REUSE) {
  1077.                 s->ac3dsp.bit_alloc_calc_bap(block->mask[ch], block->psd[ch],
  1078.                                              s->start_freq[ch], block->end_freq[ch],
  1079.                                              snr_offset, s->bit_alloc.floor,
  1080.                                              ff_ac3_bap_tab, s->ref_bap[ch][blk]);
  1081.             }
  1082.         }
  1083.     }
  1084.     return count_mantissa_bits(s);
  1085. }
  1086.  
  1087.  
  1088. /*
  1089.  * Constant bitrate bit allocation search.
  1090.  * Find the largest SNR offset that will allow data to fit in the frame.
  1091.  */
  1092. static int cbr_bit_allocation(AC3EncodeContext *s)
  1093. {
  1094.     int ch;
  1095.     int bits_left;
  1096.     int snr_offset, snr_incr;
  1097.  
  1098.     bits_left = 8 * s->frame_size - (s->frame_bits + s->exponent_bits);
  1099.     if (bits_left < 0)
  1100.         return AVERROR(EINVAL);
  1101.  
  1102.     snr_offset = s->coarse_snr_offset << 4;
  1103.  
  1104.     /* if previous frame SNR offset was 1023, check if current frame can also
  1105.        use SNR offset of 1023. if so, skip the search. */
  1106.     if ((snr_offset | s->fine_snr_offset[1]) == 1023) {
  1107.         if (bit_alloc(s, 1023) <= bits_left)
  1108.             return 0;
  1109.     }
  1110.  
  1111.     while (snr_offset >= 0 &&
  1112.            bit_alloc(s, snr_offset) > bits_left) {
  1113.         snr_offset -= 64;
  1114.     }
  1115.     if (snr_offset < 0)
  1116.         return AVERROR(EINVAL);
  1117.  
  1118.     FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
  1119.     for (snr_incr = 64; snr_incr > 0; snr_incr >>= 2) {
  1120.         while (snr_offset + snr_incr <= 1023 &&
  1121.                bit_alloc(s, snr_offset + snr_incr) <= bits_left) {
  1122.             snr_offset += snr_incr;
  1123.             FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
  1124.         }
  1125.     }
  1126.     FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
  1127.     reset_block_bap(s);
  1128.  
  1129.     s->coarse_snr_offset = snr_offset >> 4;
  1130.     for (ch = !s->cpl_on; ch <= s->channels; ch++)
  1131.         s->fine_snr_offset[ch] = snr_offset & 0xF;
  1132.  
  1133.     return 0;
  1134. }
  1135.  
  1136.  
  1137. /*
  1138.  * Perform bit allocation search.
  1139.  * Finds the SNR offset value that maximizes quality and fits in the specified
  1140.  * frame size.  Output is the SNR offset and a set of bit allocation pointers
  1141.  * used to quantize the mantissas.
  1142.  */
  1143. int ff_ac3_compute_bit_allocation(AC3EncodeContext *s)
  1144. {
  1145.     count_frame_bits(s);
  1146.  
  1147.     s->exponent_bits = count_exponent_bits(s);
  1148.  
  1149.     bit_alloc_masking(s);
  1150.  
  1151.     return cbr_bit_allocation(s);
  1152. }
  1153.  
  1154.  
  1155. /**
  1156.  * Symmetric quantization on 'levels' levels.
  1157.  *
  1158.  * @param c       unquantized coefficient
  1159.  * @param e       exponent
  1160.  * @param levels  number of quantization levels
  1161.  * @return        quantized coefficient
  1162.  */
  1163. static inline int sym_quant(int c, int e, int levels)
  1164. {
  1165.     int v = (((levels * c) >> (24 - e)) + levels) >> 1;
  1166.     av_assert2(v >= 0 && v < levels);
  1167.     return v;
  1168. }
  1169.  
  1170.  
  1171. /**
  1172.  * Asymmetric quantization on 2^qbits levels.
  1173.  *
  1174.  * @param c      unquantized coefficient
  1175.  * @param e      exponent
  1176.  * @param qbits  number of quantization bits
  1177.  * @return       quantized coefficient
  1178.  */
  1179. static inline int asym_quant(int c, int e, int qbits)
  1180. {
  1181.     int m;
  1182.  
  1183.     c = (((c << e) >> (24 - qbits)) + 1) >> 1;
  1184.     m = (1 << (qbits-1));
  1185.     if (c >= m)
  1186.         c = m - 1;
  1187.     av_assert2(c >= -m);
  1188.     return c;
  1189. }
  1190.  
  1191.  
  1192. /**
  1193.  * Quantize a set of mantissas for a single channel in a single block.
  1194.  *
  1195.  * @param s           Mantissa count context
  1196.  * @param fixed_coef  unquantized fixed-point coefficients
  1197.  * @param exp         exponents
  1198.  * @param bap         bit allocation pointer indices
  1199.  * @param[out] qmant  quantized coefficients
  1200.  * @param start_freq  starting coefficient bin
  1201.  * @param end_freq    ending coefficient bin
  1202.  */
  1203. static void quantize_mantissas_blk_ch(AC3Mant *s, int32_t *fixed_coef,
  1204.                                       uint8_t *exp, uint8_t *bap,
  1205.                                       int16_t *qmant, int start_freq,
  1206.                                       int end_freq)
  1207. {
  1208.     int i;
  1209.  
  1210.     for (i = start_freq; i < end_freq; i++) {
  1211.         int c = fixed_coef[i];
  1212.         int e = exp[i];
  1213.         int v = bap[i];
  1214.         if (v)
  1215.         switch (v) {
  1216.         case 1:
  1217.             v = sym_quant(c, e, 3);
  1218.             switch (s->mant1_cnt) {
  1219.             case 0:
  1220.                 s->qmant1_ptr = &qmant[i];
  1221.                 v = 9 * v;
  1222.                 s->mant1_cnt = 1;
  1223.                 break;
  1224.             case 1:
  1225.                 *s->qmant1_ptr += 3 * v;
  1226.                 s->mant1_cnt = 2;
  1227.                 v = 128;
  1228.                 break;
  1229.             default:
  1230.                 *s->qmant1_ptr += v;
  1231.                 s->mant1_cnt = 0;
  1232.                 v = 128;
  1233.                 break;
  1234.             }
  1235.             break;
  1236.         case 2:
  1237.             v = sym_quant(c, e, 5);
  1238.             switch (s->mant2_cnt) {
  1239.             case 0:
  1240.                 s->qmant2_ptr = &qmant[i];
  1241.                 v = 25 * v;
  1242.                 s->mant2_cnt = 1;
  1243.                 break;
  1244.             case 1:
  1245.                 *s->qmant2_ptr += 5 * v;
  1246.                 s->mant2_cnt = 2;
  1247.                 v = 128;
  1248.                 break;
  1249.             default:
  1250.                 *s->qmant2_ptr += v;
  1251.                 s->mant2_cnt = 0;
  1252.                 v = 128;
  1253.                 break;
  1254.             }
  1255.             break;
  1256.         case 3:
  1257.             v = sym_quant(c, e, 7);
  1258.             break;
  1259.         case 4:
  1260.             v = sym_quant(c, e, 11);
  1261.             switch (s->mant4_cnt) {
  1262.             case 0:
  1263.                 s->qmant4_ptr = &qmant[i];
  1264.                 v = 11 * v;
  1265.                 s->mant4_cnt = 1;
  1266.                 break;
  1267.             default:
  1268.                 *s->qmant4_ptr += v;
  1269.                 s->mant4_cnt = 0;
  1270.                 v = 128;
  1271.                 break;
  1272.             }
  1273.             break;
  1274.         case 5:
  1275.             v = sym_quant(c, e, 15);
  1276.             break;
  1277.         case 14:
  1278.             v = asym_quant(c, e, 14);
  1279.             break;
  1280.         case 15:
  1281.             v = asym_quant(c, e, 16);
  1282.             break;
  1283.         default:
  1284.             v = asym_quant(c, e, v - 1);
  1285.             break;
  1286.         }
  1287.         qmant[i] = v;
  1288.     }
  1289. }
  1290.  
  1291.  
  1292. /**
  1293.  * Quantize mantissas using coefficients, exponents, and bit allocation pointers.
  1294.  *
  1295.  * @param s  AC-3 encoder private context
  1296.  */
  1297. void ff_ac3_quantize_mantissas(AC3EncodeContext *s)
  1298. {
  1299.     int blk, ch, ch0=0, got_cpl;
  1300.  
  1301.     for (blk = 0; blk < s->num_blocks; blk++) {
  1302.         AC3Block *block = &s->blocks[blk];
  1303.         AC3Mant m = { 0 };
  1304.  
  1305.         got_cpl = !block->cpl_in_use;
  1306.         for (ch = 1; ch <= s->channels; ch++) {
  1307.             if (!got_cpl && ch > 1 && block->channel_in_cpl[ch-1]) {
  1308.                 ch0     = ch - 1;
  1309.                 ch      = CPL_CH;
  1310.                 got_cpl = 1;
  1311.             }
  1312.             quantize_mantissas_blk_ch(&m, block->fixed_coef[ch],
  1313.                                       s->blocks[s->exp_ref_block[ch][blk]].exp[ch],
  1314.                                       s->ref_bap[ch][blk], block->qmant[ch],
  1315.                                       s->start_freq[ch], block->end_freq[ch]);
  1316.             if (ch == CPL_CH)
  1317.                 ch = ch0;
  1318.         }
  1319.     }
  1320. }
  1321.  
  1322.  
  1323. /*
  1324.  * Write the AC-3 frame header to the output bitstream.
  1325.  */
  1326. static void ac3_output_frame_header(AC3EncodeContext *s)
  1327. {
  1328.     AC3EncOptions *opt = &s->options;
  1329.  
  1330.     put_bits(&s->pb, 16, 0x0b77);   /* frame header */
  1331.     put_bits(&s->pb, 16, 0);        /* crc1: will be filled later */
  1332.     put_bits(&s->pb, 2,  s->bit_alloc.sr_code);
  1333.     put_bits(&s->pb, 6,  s->frame_size_code + (s->frame_size - s->frame_size_min) / 2);
  1334.     put_bits(&s->pb, 5,  s->bitstream_id);
  1335.     put_bits(&s->pb, 3,  s->bitstream_mode);
  1336.     put_bits(&s->pb, 3,  s->channel_mode);
  1337.     if ((s->channel_mode & 0x01) && s->channel_mode != AC3_CHMODE_MONO)
  1338.         put_bits(&s->pb, 2, s->center_mix_level);
  1339.     if (s->channel_mode & 0x04)
  1340.         put_bits(&s->pb, 2, s->surround_mix_level);
  1341.     if (s->channel_mode == AC3_CHMODE_STEREO)
  1342.         put_bits(&s->pb, 2, opt->dolby_surround_mode);
  1343.     put_bits(&s->pb, 1, s->lfe_on); /* LFE */
  1344.     put_bits(&s->pb, 5, -opt->dialogue_level);
  1345.     put_bits(&s->pb, 1, 0);         /* no compression control word */
  1346.     put_bits(&s->pb, 1, 0);         /* no lang code */
  1347.     put_bits(&s->pb, 1, opt->audio_production_info);
  1348.     if (opt->audio_production_info) {
  1349.         put_bits(&s->pb, 5, opt->mixing_level - 80);
  1350.         put_bits(&s->pb, 2, opt->room_type);
  1351.     }
  1352.     put_bits(&s->pb, 1, opt->copyright);
  1353.     put_bits(&s->pb, 1, opt->original);
  1354.     if (s->bitstream_id == 6) {
  1355.         /* alternate bit stream syntax */
  1356.         put_bits(&s->pb, 1, opt->extended_bsi_1);
  1357.         if (opt->extended_bsi_1) {
  1358.             put_bits(&s->pb, 2, opt->preferred_stereo_downmix);
  1359.             put_bits(&s->pb, 3, s->ltrt_center_mix_level);
  1360.             put_bits(&s->pb, 3, s->ltrt_surround_mix_level);
  1361.             put_bits(&s->pb, 3, s->loro_center_mix_level);
  1362.             put_bits(&s->pb, 3, s->loro_surround_mix_level);
  1363.         }
  1364.         put_bits(&s->pb, 1, opt->extended_bsi_2);
  1365.         if (opt->extended_bsi_2) {
  1366.             put_bits(&s->pb, 2, opt->dolby_surround_ex_mode);
  1367.             put_bits(&s->pb, 2, opt->dolby_headphone_mode);
  1368.             put_bits(&s->pb, 1, opt->ad_converter_type);
  1369.             put_bits(&s->pb, 9, 0);     /* xbsi2 and encinfo : reserved */
  1370.         }
  1371.     } else {
  1372.     put_bits(&s->pb, 1, 0);         /* no time code 1 */
  1373.     put_bits(&s->pb, 1, 0);         /* no time code 2 */
  1374.     }
  1375.     put_bits(&s->pb, 1, 0);         /* no additional bit stream info */
  1376. }
  1377.  
  1378.  
  1379. /*
  1380.  * Write one audio block to the output bitstream.
  1381.  */
  1382. static void output_audio_block(AC3EncodeContext *s, int blk)
  1383. {
  1384.     int ch, i, baie, bnd, got_cpl, ch0;
  1385.     AC3Block *block = &s->blocks[blk];
  1386.  
  1387.     /* block switching */
  1388.     if (!s->eac3) {
  1389.         for (ch = 0; ch < s->fbw_channels; ch++)
  1390.             put_bits(&s->pb, 1, 0);
  1391.     }
  1392.  
  1393.     /* dither flags */
  1394.     if (!s->eac3) {
  1395.         for (ch = 0; ch < s->fbw_channels; ch++)
  1396.             put_bits(&s->pb, 1, 1);
  1397.     }
  1398.  
  1399.     /* dynamic range codes */
  1400.     put_bits(&s->pb, 1, 0);
  1401.  
  1402.     /* spectral extension */
  1403.     if (s->eac3)
  1404.         put_bits(&s->pb, 1, 0);
  1405.  
  1406.     /* channel coupling */
  1407.     if (!s->eac3)
  1408.         put_bits(&s->pb, 1, block->new_cpl_strategy);
  1409.     if (block->new_cpl_strategy) {
  1410.         if (!s->eac3)
  1411.             put_bits(&s->pb, 1, block->cpl_in_use);
  1412.         if (block->cpl_in_use) {
  1413.             int start_sub, end_sub;
  1414.             if (s->eac3)
  1415.                 put_bits(&s->pb, 1, 0); /* enhanced coupling */
  1416.             if (!s->eac3 || s->channel_mode != AC3_CHMODE_STEREO) {
  1417.                 for (ch = 1; ch <= s->fbw_channels; ch++)
  1418.                     put_bits(&s->pb, 1, block->channel_in_cpl[ch]);
  1419.             }
  1420.             if (s->channel_mode == AC3_CHMODE_STEREO)
  1421.                 put_bits(&s->pb, 1, 0); /* phase flags in use */
  1422.             start_sub = (s->start_freq[CPL_CH] - 37) / 12;
  1423.             end_sub   = (s->cpl_end_freq       - 37) / 12;
  1424.             put_bits(&s->pb, 4, start_sub);
  1425.             put_bits(&s->pb, 4, end_sub - 3);
  1426.             /* coupling band structure */
  1427.             if (s->eac3) {
  1428.                 put_bits(&s->pb, 1, 0); /* use default */
  1429.             } else {
  1430.                 for (bnd = start_sub+1; bnd < end_sub; bnd++)
  1431.                     put_bits(&s->pb, 1, ff_eac3_default_cpl_band_struct[bnd]);
  1432.             }
  1433.         }
  1434.     }
  1435.  
  1436.     /* coupling coordinates */
  1437.     if (block->cpl_in_use) {
  1438.         for (ch = 1; ch <= s->fbw_channels; ch++) {
  1439.             if (block->channel_in_cpl[ch]) {
  1440.                 if (!s->eac3 || block->new_cpl_coords[ch] != 2)
  1441.                     put_bits(&s->pb, 1, block->new_cpl_coords[ch]);
  1442.                 if (block->new_cpl_coords[ch]) {
  1443.                     put_bits(&s->pb, 2, block->cpl_master_exp[ch]);
  1444.                     for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
  1445.                         put_bits(&s->pb, 4, block->cpl_coord_exp [ch][bnd]);
  1446.                         put_bits(&s->pb, 4, block->cpl_coord_mant[ch][bnd]);
  1447.                     }
  1448.                 }
  1449.             }
  1450.         }
  1451.     }
  1452.  
  1453.     /* stereo rematrixing */
  1454.     if (s->channel_mode == AC3_CHMODE_STEREO) {
  1455.         if (!s->eac3 || blk > 0)
  1456.             put_bits(&s->pb, 1, block->new_rematrixing_strategy);
  1457.         if (block->new_rematrixing_strategy) {
  1458.             /* rematrixing flags */
  1459.             for (bnd = 0; bnd < block->num_rematrixing_bands; bnd++)
  1460.                 put_bits(&s->pb, 1, block->rematrixing_flags[bnd]);
  1461.         }
  1462.     }
  1463.  
  1464.     /* exponent strategy */
  1465.     if (!s->eac3) {
  1466.         for (ch = !block->cpl_in_use; ch <= s->fbw_channels; ch++)
  1467.             put_bits(&s->pb, 2, s->exp_strategy[ch][blk]);
  1468.         if (s->lfe_on)
  1469.             put_bits(&s->pb, 1, s->exp_strategy[s->lfe_channel][blk]);
  1470.     }
  1471.  
  1472.     /* bandwidth */
  1473.     for (ch = 1; ch <= s->fbw_channels; ch++) {
  1474.         if (s->exp_strategy[ch][blk] != EXP_REUSE && !block->channel_in_cpl[ch])
  1475.             put_bits(&s->pb, 6, s->bandwidth_code);
  1476.     }
  1477.  
  1478.     /* exponents */
  1479.     for (ch = !block->cpl_in_use; ch <= s->channels; ch++) {
  1480.         int nb_groups;
  1481.         int cpl = (ch == CPL_CH);
  1482.  
  1483.         if (s->exp_strategy[ch][blk] == EXP_REUSE)
  1484.             continue;
  1485.  
  1486.         /* DC exponent */
  1487.         put_bits(&s->pb, 4, block->grouped_exp[ch][0] >> cpl);
  1488.  
  1489.         /* exponent groups */
  1490.         nb_groups = exponent_group_tab[cpl][s->exp_strategy[ch][blk]-1][block->end_freq[ch]-s->start_freq[ch]];
  1491.         for (i = 1; i <= nb_groups; i++)
  1492.             put_bits(&s->pb, 7, block->grouped_exp[ch][i]);
  1493.  
  1494.         /* gain range info */
  1495.         if (ch != s->lfe_channel && !cpl)
  1496.             put_bits(&s->pb, 2, 0);
  1497.     }
  1498.  
  1499.     /* bit allocation info */
  1500.     if (!s->eac3) {
  1501.         baie = (blk == 0);
  1502.         put_bits(&s->pb, 1, baie);
  1503.         if (baie) {
  1504.             put_bits(&s->pb, 2, s->slow_decay_code);
  1505.             put_bits(&s->pb, 2, s->fast_decay_code);
  1506.             put_bits(&s->pb, 2, s->slow_gain_code);
  1507.             put_bits(&s->pb, 2, s->db_per_bit_code);
  1508.             put_bits(&s->pb, 3, s->floor_code);
  1509.         }
  1510.     }
  1511.  
  1512.     /* snr offset */
  1513.     if (!s->eac3) {
  1514.         put_bits(&s->pb, 1, block->new_snr_offsets);
  1515.         if (block->new_snr_offsets) {
  1516.             put_bits(&s->pb, 6, s->coarse_snr_offset);
  1517.             for (ch = !block->cpl_in_use; ch <= s->channels; ch++) {
  1518.                 put_bits(&s->pb, 4, s->fine_snr_offset[ch]);
  1519.                 put_bits(&s->pb, 3, s->fast_gain_code[ch]);
  1520.             }
  1521.         }
  1522.     } else {
  1523.         put_bits(&s->pb, 1, 0); /* no converter snr offset */
  1524.     }
  1525.  
  1526.     /* coupling leak */
  1527.     if (block->cpl_in_use) {
  1528.         if (!s->eac3 || block->new_cpl_leak != 2)
  1529.             put_bits(&s->pb, 1, block->new_cpl_leak);
  1530.         if (block->new_cpl_leak) {
  1531.             put_bits(&s->pb, 3, s->bit_alloc.cpl_fast_leak);
  1532.             put_bits(&s->pb, 3, s->bit_alloc.cpl_slow_leak);
  1533.         }
  1534.     }
  1535.  
  1536.     if (!s->eac3) {
  1537.         put_bits(&s->pb, 1, 0); /* no delta bit allocation */
  1538.         put_bits(&s->pb, 1, 0); /* no data to skip */
  1539.     }
  1540.  
  1541.     /* mantissas */
  1542.     got_cpl = !block->cpl_in_use;
  1543.     for (ch = 1; ch <= s->channels; ch++) {
  1544.         int b, q;
  1545.  
  1546.         if (!got_cpl && ch > 1 && block->channel_in_cpl[ch-1]) {
  1547.             ch0     = ch - 1;
  1548.             ch      = CPL_CH;
  1549.             got_cpl = 1;
  1550.         }
  1551.         for (i = s->start_freq[ch]; i < block->end_freq[ch]; i++) {
  1552.             q = block->qmant[ch][i];
  1553.             b = s->ref_bap[ch][blk][i];
  1554.             switch (b) {
  1555.             case 0:                                          break;
  1556.             case 1: if (q != 128) put_bits (&s->pb,   5, q); break;
  1557.             case 2: if (q != 128) put_bits (&s->pb,   7, q); break;
  1558.             case 3:               put_sbits(&s->pb,   3, q); break;
  1559.             case 4: if (q != 128) put_bits (&s->pb,   7, q); break;
  1560.             case 14:              put_sbits(&s->pb,  14, q); break;
  1561.             case 15:              put_sbits(&s->pb,  16, q); break;
  1562.             default:              put_sbits(&s->pb, b-1, q); break;
  1563.             }
  1564.         }
  1565.         if (ch == CPL_CH)
  1566.             ch = ch0;
  1567.     }
  1568. }
  1569.  
  1570.  
  1571. /** CRC-16 Polynomial */
  1572. #define CRC16_POLY ((1 << 0) | (1 << 2) | (1 << 15) | (1 << 16))
  1573.  
  1574.  
  1575. static unsigned int mul_poly(unsigned int a, unsigned int b, unsigned int poly)
  1576. {
  1577.     unsigned int c;
  1578.  
  1579.     c = 0;
  1580.     while (a) {
  1581.         if (a & 1)
  1582.             c ^= b;
  1583.         a = a >> 1;
  1584.         b = b << 1;
  1585.         if (b & (1 << 16))
  1586.             b ^= poly;
  1587.     }
  1588.     return c;
  1589. }
  1590.  
  1591.  
  1592. static unsigned int pow_poly(unsigned int a, unsigned int n, unsigned int poly)
  1593. {
  1594.     unsigned int r;
  1595.     r = 1;
  1596.     while (n) {
  1597.         if (n & 1)
  1598.             r = mul_poly(r, a, poly);
  1599.         a = mul_poly(a, a, poly);
  1600.         n >>= 1;
  1601.     }
  1602.     return r;
  1603. }
  1604.  
  1605.  
  1606. /*
  1607.  * Fill the end of the frame with 0's and compute the two CRCs.
  1608.  */
  1609. static void output_frame_end(AC3EncodeContext *s)
  1610. {
  1611.     const AVCRC *crc_ctx = av_crc_get_table(AV_CRC_16_ANSI);
  1612.     int frame_size_58, pad_bytes, crc1, crc2_partial, crc2, crc_inv;
  1613.     uint8_t *frame;
  1614.  
  1615.     frame_size_58 = ((s->frame_size >> 2) + (s->frame_size >> 4)) << 1;
  1616.  
  1617.     /* pad the remainder of the frame with zeros */
  1618.     av_assert2(s->frame_size * 8 - put_bits_count(&s->pb) >= 18);
  1619.     flush_put_bits(&s->pb);
  1620.     frame = s->pb.buf;
  1621.     pad_bytes = s->frame_size - (put_bits_ptr(&s->pb) - frame) - 2;
  1622.     av_assert2(pad_bytes >= 0);
  1623.     if (pad_bytes > 0)
  1624.         memset(put_bits_ptr(&s->pb), 0, pad_bytes);
  1625.  
  1626.     if (s->eac3) {
  1627.         /* compute crc2 */
  1628.         crc2_partial = av_crc(crc_ctx, 0, frame + 2, s->frame_size - 5);
  1629.     } else {
  1630.     /* compute crc1 */
  1631.     /* this is not so easy because it is at the beginning of the data... */
  1632.     crc1    = av_bswap16(av_crc(crc_ctx, 0, frame + 4, frame_size_58 - 4));
  1633.     crc_inv = s->crc_inv[s->frame_size > s->frame_size_min];
  1634.     crc1    = mul_poly(crc_inv, crc1, CRC16_POLY);
  1635.     AV_WB16(frame + 2, crc1);
  1636.  
  1637.     /* compute crc2 */
  1638.     crc2_partial = av_crc(crc_ctx, 0, frame + frame_size_58,
  1639.                           s->frame_size - frame_size_58 - 3);
  1640.     }
  1641.     crc2 = av_crc(crc_ctx, crc2_partial, frame + s->frame_size - 3, 1);
  1642.     /* ensure crc2 does not match sync word by flipping crcrsv bit if needed */
  1643.     if (crc2 == 0x770B) {
  1644.         frame[s->frame_size - 3] ^= 0x1;
  1645.         crc2 = av_crc(crc_ctx, crc2_partial, frame + s->frame_size - 3, 1);
  1646.     }
  1647.     crc2 = av_bswap16(crc2);
  1648.     AV_WB16(frame + s->frame_size - 2, crc2);
  1649. }
  1650.  
  1651.  
  1652. /**
  1653.  * Write the frame to the output bitstream.
  1654.  *
  1655.  * @param s      AC-3 encoder private context
  1656.  * @param frame  output data buffer
  1657.  */
  1658. void ff_ac3_output_frame(AC3EncodeContext *s, unsigned char *frame)
  1659. {
  1660.     int blk;
  1661.  
  1662.     init_put_bits(&s->pb, frame, AC3_MAX_CODED_FRAME_SIZE);
  1663.  
  1664.     s->output_frame_header(s);
  1665.  
  1666.     for (blk = 0; blk < s->num_blocks; blk++)
  1667.         output_audio_block(s, blk);
  1668.  
  1669.     output_frame_end(s);
  1670. }
  1671.  
  1672.  
  1673. static void dprint_options(AC3EncodeContext *s)
  1674. {
  1675. #ifdef DEBUG
  1676.     AVCodecContext *avctx = s->avctx;
  1677.     AC3EncOptions *opt = &s->options;
  1678.     char strbuf[32];
  1679.  
  1680.     switch (s->bitstream_id) {
  1681.     case  6:  av_strlcpy(strbuf, "AC-3 (alt syntax)",       32); break;
  1682.     case  8:  av_strlcpy(strbuf, "AC-3 (standard)",         32); break;
  1683.     case  9:  av_strlcpy(strbuf, "AC-3 (dnet half-rate)",   32); break;
  1684.     case 10:  av_strlcpy(strbuf, "AC-3 (dnet quater-rate)", 32); break;
  1685.     case 16:  av_strlcpy(strbuf, "E-AC-3 (enhanced)",       32); break;
  1686.     default: snprintf(strbuf, 32, "ERROR");
  1687.     }
  1688.     av_dlog(avctx, "bitstream_id: %s (%d)\n", strbuf, s->bitstream_id);
  1689.     av_dlog(avctx, "sample_fmt: %s\n", av_get_sample_fmt_name(avctx->sample_fmt));
  1690.     av_get_channel_layout_string(strbuf, 32, s->channels, avctx->channel_layout);
  1691.     av_dlog(avctx, "channel_layout: %s\n", strbuf);
  1692.     av_dlog(avctx, "sample_rate: %d\n", s->sample_rate);
  1693.     av_dlog(avctx, "bit_rate: %d\n", s->bit_rate);
  1694.     av_dlog(avctx, "blocks/frame: %d (code=%d)\n", s->num_blocks, s->num_blks_code);
  1695.     if (s->cutoff)
  1696.         av_dlog(avctx, "cutoff: %d\n", s->cutoff);
  1697.  
  1698.     av_dlog(avctx, "per_frame_metadata: %s\n",
  1699.             opt->allow_per_frame_metadata?"on":"off");
  1700.     if (s->has_center)
  1701.         av_dlog(avctx, "center_mixlev: %0.3f (%d)\n", opt->center_mix_level,
  1702.                 s->center_mix_level);
  1703.     else
  1704.         av_dlog(avctx, "center_mixlev: {not written}\n");
  1705.     if (s->has_surround)
  1706.         av_dlog(avctx, "surround_mixlev: %0.3f (%d)\n", opt->surround_mix_level,
  1707.                 s->surround_mix_level);
  1708.     else
  1709.         av_dlog(avctx, "surround_mixlev: {not written}\n");
  1710.     if (opt->audio_production_info) {
  1711.         av_dlog(avctx, "mixing_level: %ddB\n", opt->mixing_level);
  1712.         switch (opt->room_type) {
  1713.         case AC3ENC_OPT_NOT_INDICATED: av_strlcpy(strbuf, "notindicated", 32); break;
  1714.         case AC3ENC_OPT_LARGE_ROOM:    av_strlcpy(strbuf, "large", 32);        break;
  1715.         case AC3ENC_OPT_SMALL_ROOM:    av_strlcpy(strbuf, "small", 32);        break;
  1716.         default: snprintf(strbuf, 32, "ERROR (%d)", opt->room_type);
  1717.         }
  1718.         av_dlog(avctx, "room_type: %s\n", strbuf);
  1719.     } else {
  1720.         av_dlog(avctx, "mixing_level: {not written}\n");
  1721.         av_dlog(avctx, "room_type: {not written}\n");
  1722.     }
  1723.     av_dlog(avctx, "copyright: %s\n", opt->copyright?"on":"off");
  1724.     av_dlog(avctx, "dialnorm: %ddB\n", opt->dialogue_level);
  1725.     if (s->channel_mode == AC3_CHMODE_STEREO) {
  1726.         switch (opt->dolby_surround_mode) {
  1727.         case AC3ENC_OPT_NOT_INDICATED: av_strlcpy(strbuf, "notindicated", 32); break;
  1728.         case AC3ENC_OPT_MODE_ON:       av_strlcpy(strbuf, "on", 32);           break;
  1729.         case AC3ENC_OPT_MODE_OFF:      av_strlcpy(strbuf, "off", 32);          break;
  1730.         default: snprintf(strbuf, 32, "ERROR (%d)", opt->dolby_surround_mode);
  1731.         }
  1732.         av_dlog(avctx, "dsur_mode: %s\n", strbuf);
  1733.     } else {
  1734.         av_dlog(avctx, "dsur_mode: {not written}\n");
  1735.     }
  1736.     av_dlog(avctx, "original: %s\n", opt->original?"on":"off");
  1737.  
  1738.     if (s->bitstream_id == 6) {
  1739.         if (opt->extended_bsi_1) {
  1740.             switch (opt->preferred_stereo_downmix) {
  1741.             case AC3ENC_OPT_NOT_INDICATED: av_strlcpy(strbuf, "notindicated", 32); break;
  1742.             case AC3ENC_OPT_DOWNMIX_LTRT:  av_strlcpy(strbuf, "ltrt", 32);         break;
  1743.             case AC3ENC_OPT_DOWNMIX_LORO:  av_strlcpy(strbuf, "loro", 32);         break;
  1744.             default: snprintf(strbuf, 32, "ERROR (%d)", opt->preferred_stereo_downmix);
  1745.             }
  1746.             av_dlog(avctx, "dmix_mode: %s\n", strbuf);
  1747.             av_dlog(avctx, "ltrt_cmixlev: %0.3f (%d)\n",
  1748.                     opt->ltrt_center_mix_level, s->ltrt_center_mix_level);
  1749.             av_dlog(avctx, "ltrt_surmixlev: %0.3f (%d)\n",
  1750.                     opt->ltrt_surround_mix_level, s->ltrt_surround_mix_level);
  1751.             av_dlog(avctx, "loro_cmixlev: %0.3f (%d)\n",
  1752.                     opt->loro_center_mix_level, s->loro_center_mix_level);
  1753.             av_dlog(avctx, "loro_surmixlev: %0.3f (%d)\n",
  1754.                     opt->loro_surround_mix_level, s->loro_surround_mix_level);
  1755.         } else {
  1756.             av_dlog(avctx, "extended bitstream info 1: {not written}\n");
  1757.         }
  1758.         if (opt->extended_bsi_2) {
  1759.             switch (opt->dolby_surround_ex_mode) {
  1760.             case AC3ENC_OPT_NOT_INDICATED: av_strlcpy(strbuf, "notindicated", 32); break;
  1761.             case AC3ENC_OPT_MODE_ON:       av_strlcpy(strbuf, "on", 32);           break;
  1762.             case AC3ENC_OPT_MODE_OFF:      av_strlcpy(strbuf, "off", 32);          break;
  1763.             default: snprintf(strbuf, 32, "ERROR (%d)", opt->dolby_surround_ex_mode);
  1764.             }
  1765.             av_dlog(avctx, "dsurex_mode: %s\n", strbuf);
  1766.             switch (opt->dolby_headphone_mode) {
  1767.             case AC3ENC_OPT_NOT_INDICATED: av_strlcpy(strbuf, "notindicated", 32); break;
  1768.             case AC3ENC_OPT_MODE_ON:       av_strlcpy(strbuf, "on", 32);           break;
  1769.             case AC3ENC_OPT_MODE_OFF:      av_strlcpy(strbuf, "off", 32);          break;
  1770.             default: snprintf(strbuf, 32, "ERROR (%d)", opt->dolby_headphone_mode);
  1771.             }
  1772.             av_dlog(avctx, "dheadphone_mode: %s\n", strbuf);
  1773.  
  1774.             switch (opt->ad_converter_type) {
  1775.             case AC3ENC_OPT_ADCONV_STANDARD: av_strlcpy(strbuf, "standard", 32); break;
  1776.             case AC3ENC_OPT_ADCONV_HDCD:     av_strlcpy(strbuf, "hdcd", 32);     break;
  1777.             default: snprintf(strbuf, 32, "ERROR (%d)", opt->ad_converter_type);
  1778.             }
  1779.             av_dlog(avctx, "ad_conv_type: %s\n", strbuf);
  1780.         } else {
  1781.             av_dlog(avctx, "extended bitstream info 2: {not written}\n");
  1782.         }
  1783.     }
  1784. #endif
  1785. }
  1786.  
  1787.  
  1788. #define FLT_OPTION_THRESHOLD 0.01
  1789.  
  1790. static int validate_float_option(float v, const float *v_list, int v_list_size)
  1791. {
  1792.     int i;
  1793.  
  1794.     for (i = 0; i < v_list_size; i++) {
  1795.         if (v < (v_list[i] + FLT_OPTION_THRESHOLD) &&
  1796.             v > (v_list[i] - FLT_OPTION_THRESHOLD))
  1797.             break;
  1798.     }
  1799.     if (i == v_list_size)
  1800.         return -1;
  1801.  
  1802.     return i;
  1803. }
  1804.  
  1805.  
  1806. static void validate_mix_level(void *log_ctx, const char *opt_name,
  1807.                                float *opt_param, const float *list,
  1808.                                int list_size, int default_value, int min_value,
  1809.                                int *ctx_param)
  1810. {
  1811.     int mixlev = validate_float_option(*opt_param, list, list_size);
  1812.     if (mixlev < min_value) {
  1813.         mixlev = default_value;
  1814.         if (*opt_param >= 0.0) {
  1815.             av_log(log_ctx, AV_LOG_WARNING, "requested %s is not valid. using "
  1816.                    "default value: %0.3f\n", opt_name, list[mixlev]);
  1817.         }
  1818.     }
  1819.     *opt_param = list[mixlev];
  1820.     *ctx_param = mixlev;
  1821. }
  1822.  
  1823.  
  1824. /**
  1825.  * Validate metadata options as set by AVOption system.
  1826.  * These values can optionally be changed per-frame.
  1827.  *
  1828.  * @param s  AC-3 encoder private context
  1829.  */
  1830. int ff_ac3_validate_metadata(AC3EncodeContext *s)
  1831. {
  1832.     AVCodecContext *avctx = s->avctx;
  1833.     AC3EncOptions *opt = &s->options;
  1834.  
  1835.     opt->audio_production_info = 0;
  1836.     opt->extended_bsi_1        = 0;
  1837.     opt->extended_bsi_2        = 0;
  1838.     opt->eac3_mixing_metadata  = 0;
  1839.     opt->eac3_info_metadata    = 0;
  1840.  
  1841.     /* determine mixing metadata / xbsi1 use */
  1842.     if (s->channel_mode > AC3_CHMODE_STEREO && opt->preferred_stereo_downmix != AC3ENC_OPT_NONE) {
  1843.         opt->extended_bsi_1       = 1;
  1844.         opt->eac3_mixing_metadata = 1;
  1845.     }
  1846.     if (s->has_center &&
  1847.         (opt->ltrt_center_mix_level >= 0 || opt->loro_center_mix_level >= 0)) {
  1848.         opt->extended_bsi_1       = 1;
  1849.         opt->eac3_mixing_metadata = 1;
  1850.     }
  1851.     if (s->has_surround &&
  1852.         (opt->ltrt_surround_mix_level >= 0 || opt->loro_surround_mix_level >= 0)) {
  1853.         opt->extended_bsi_1       = 1;
  1854.         opt->eac3_mixing_metadata = 1;
  1855.     }
  1856.  
  1857.     if (s->eac3) {
  1858.         /* determine info metadata use */
  1859.         if (avctx->audio_service_type != AV_AUDIO_SERVICE_TYPE_MAIN)
  1860.             opt->eac3_info_metadata = 1;
  1861.         if (opt->copyright != AC3ENC_OPT_NONE || opt->original != AC3ENC_OPT_NONE)
  1862.             opt->eac3_info_metadata = 1;
  1863.         if (s->channel_mode == AC3_CHMODE_STEREO &&
  1864.             (opt->dolby_headphone_mode != AC3ENC_OPT_NONE || opt->dolby_surround_mode != AC3ENC_OPT_NONE))
  1865.             opt->eac3_info_metadata = 1;
  1866.         if (s->channel_mode >= AC3_CHMODE_2F2R && opt->dolby_surround_ex_mode != AC3ENC_OPT_NONE)
  1867.             opt->eac3_info_metadata = 1;
  1868.         if (opt->mixing_level != AC3ENC_OPT_NONE || opt->room_type != AC3ENC_OPT_NONE ||
  1869.             opt->ad_converter_type != AC3ENC_OPT_NONE) {
  1870.             opt->audio_production_info = 1;
  1871.             opt->eac3_info_metadata    = 1;
  1872.         }
  1873.     } else {
  1874.         /* determine audio production info use */
  1875.         if (opt->mixing_level != AC3ENC_OPT_NONE || opt->room_type != AC3ENC_OPT_NONE)
  1876.             opt->audio_production_info = 1;
  1877.  
  1878.         /* determine xbsi2 use */
  1879.         if (s->channel_mode >= AC3_CHMODE_2F2R && opt->dolby_surround_ex_mode != AC3ENC_OPT_NONE)
  1880.             opt->extended_bsi_2 = 1;
  1881.         if (s->channel_mode == AC3_CHMODE_STEREO && opt->dolby_headphone_mode != AC3ENC_OPT_NONE)
  1882.             opt->extended_bsi_2 = 1;
  1883.         if (opt->ad_converter_type != AC3ENC_OPT_NONE)
  1884.             opt->extended_bsi_2 = 1;
  1885.     }
  1886.  
  1887.     /* validate AC-3 mixing levels */
  1888.     if (!s->eac3) {
  1889.         if (s->has_center) {
  1890.             validate_mix_level(avctx, "center_mix_level", &opt->center_mix_level,
  1891.                             cmixlev_options, CMIXLEV_NUM_OPTIONS, 1, 0,
  1892.                             &s->center_mix_level);
  1893.         }
  1894.         if (s->has_surround) {
  1895.             validate_mix_level(avctx, "surround_mix_level", &opt->surround_mix_level,
  1896.                             surmixlev_options, SURMIXLEV_NUM_OPTIONS, 1, 0,
  1897.                             &s->surround_mix_level);
  1898.         }
  1899.     }
  1900.  
  1901.     /* validate extended bsi 1 / mixing metadata */
  1902.     if (opt->extended_bsi_1 || opt->eac3_mixing_metadata) {
  1903.         /* default preferred stereo downmix */
  1904.         if (opt->preferred_stereo_downmix == AC3ENC_OPT_NONE)
  1905.             opt->preferred_stereo_downmix = AC3ENC_OPT_NOT_INDICATED;
  1906.         if (!s->eac3 || s->has_center) {
  1907.             /* validate Lt/Rt center mix level */
  1908.             validate_mix_level(avctx, "ltrt_center_mix_level",
  1909.                                &opt->ltrt_center_mix_level, extmixlev_options,
  1910.                                EXTMIXLEV_NUM_OPTIONS, 5, 0,
  1911.                                &s->ltrt_center_mix_level);
  1912.             /* validate Lo/Ro center mix level */
  1913.             validate_mix_level(avctx, "loro_center_mix_level",
  1914.                                &opt->loro_center_mix_level, extmixlev_options,
  1915.                                EXTMIXLEV_NUM_OPTIONS, 5, 0,
  1916.                                &s->loro_center_mix_level);
  1917.         }
  1918.         if (!s->eac3 || s->has_surround) {
  1919.             /* validate Lt/Rt surround mix level */
  1920.             validate_mix_level(avctx, "ltrt_surround_mix_level",
  1921.                                &opt->ltrt_surround_mix_level, extmixlev_options,
  1922.                                EXTMIXLEV_NUM_OPTIONS, 6, 3,
  1923.                                &s->ltrt_surround_mix_level);
  1924.             /* validate Lo/Ro surround mix level */
  1925.             validate_mix_level(avctx, "loro_surround_mix_level",
  1926.                                &opt->loro_surround_mix_level, extmixlev_options,
  1927.                                EXTMIXLEV_NUM_OPTIONS, 6, 3,
  1928.                                &s->loro_surround_mix_level);
  1929.         }
  1930.     }
  1931.  
  1932.     /* validate audio service type / channels combination */
  1933.     if ((avctx->audio_service_type == AV_AUDIO_SERVICE_TYPE_KARAOKE &&
  1934.          avctx->channels == 1) ||
  1935.         ((avctx->audio_service_type == AV_AUDIO_SERVICE_TYPE_COMMENTARY ||
  1936.           avctx->audio_service_type == AV_AUDIO_SERVICE_TYPE_EMERGENCY  ||
  1937.           avctx->audio_service_type == AV_AUDIO_SERVICE_TYPE_VOICE_OVER)
  1938.          && avctx->channels > 1)) {
  1939.         av_log(avctx, AV_LOG_ERROR, "invalid audio service type for the "
  1940.                                     "specified number of channels\n");
  1941.         return AVERROR(EINVAL);
  1942.     }
  1943.  
  1944.     /* validate extended bsi 2 / info metadata */
  1945.     if (opt->extended_bsi_2 || opt->eac3_info_metadata) {
  1946.         /* default dolby headphone mode */
  1947.         if (opt->dolby_headphone_mode == AC3ENC_OPT_NONE)
  1948.             opt->dolby_headphone_mode = AC3ENC_OPT_NOT_INDICATED;
  1949.         /* default dolby surround ex mode */
  1950.         if (opt->dolby_surround_ex_mode == AC3ENC_OPT_NONE)
  1951.             opt->dolby_surround_ex_mode = AC3ENC_OPT_NOT_INDICATED;
  1952.         /* default A/D converter type */
  1953.         if (opt->ad_converter_type == AC3ENC_OPT_NONE)
  1954.             opt->ad_converter_type = AC3ENC_OPT_ADCONV_STANDARD;
  1955.     }
  1956.  
  1957.     /* copyright & original defaults */
  1958.     if (!s->eac3 || opt->eac3_info_metadata) {
  1959.         /* default copyright */
  1960.         if (opt->copyright == AC3ENC_OPT_NONE)
  1961.             opt->copyright = AC3ENC_OPT_OFF;
  1962.         /* default original */
  1963.         if (opt->original == AC3ENC_OPT_NONE)
  1964.             opt->original = AC3ENC_OPT_ON;
  1965.     }
  1966.  
  1967.     /* dolby surround mode default */
  1968.     if (!s->eac3 || opt->eac3_info_metadata) {
  1969.         if (opt->dolby_surround_mode == AC3ENC_OPT_NONE)
  1970.             opt->dolby_surround_mode = AC3ENC_OPT_NOT_INDICATED;
  1971.     }
  1972.  
  1973.     /* validate audio production info */
  1974.     if (opt->audio_production_info) {
  1975.         if (opt->mixing_level == AC3ENC_OPT_NONE) {
  1976.             av_log(avctx, AV_LOG_ERROR, "mixing_level must be set if "
  1977.                    "room_type is set\n");
  1978.             return AVERROR(EINVAL);
  1979.         }
  1980.         if (opt->mixing_level < 80) {
  1981.             av_log(avctx, AV_LOG_ERROR, "invalid mixing level. must be between "
  1982.                    "80dB and 111dB\n");
  1983.             return AVERROR(EINVAL);
  1984.         }
  1985.         /* default room type */
  1986.         if (opt->room_type == AC3ENC_OPT_NONE)
  1987.             opt->room_type = AC3ENC_OPT_NOT_INDICATED;
  1988.     }
  1989.  
  1990.     /* set bitstream id for alternate bitstream syntax */
  1991.     if (!s->eac3 && (opt->extended_bsi_1 || opt->extended_bsi_2)) {
  1992.         if (s->bitstream_id > 8 && s->bitstream_id < 11) {
  1993.             static int warn_once = 1;
  1994.             if (warn_once) {
  1995.                 av_log(avctx, AV_LOG_WARNING, "alternate bitstream syntax is "
  1996.                        "not compatible with reduced samplerates. writing of "
  1997.                        "extended bitstream information will be disabled.\n");
  1998.                 warn_once = 0;
  1999.             }
  2000.         } else {
  2001.             s->bitstream_id = 6;
  2002.         }
  2003.     }
  2004.  
  2005.     return 0;
  2006. }
  2007.  
  2008.  
  2009. /**
  2010.  * Finalize encoding and free any memory allocated by the encoder.
  2011.  *
  2012.  * @param avctx  Codec context
  2013.  */
  2014. av_cold int ff_ac3_encode_close(AVCodecContext *avctx)
  2015. {
  2016.     int blk, ch;
  2017.     AC3EncodeContext *s = avctx->priv_data;
  2018.  
  2019.     av_freep(&s->windowed_samples);
  2020.     if (s->planar_samples)
  2021.     for (ch = 0; ch < s->channels; ch++)
  2022.         av_freep(&s->planar_samples[ch]);
  2023.     av_freep(&s->planar_samples);
  2024.     av_freep(&s->bap_buffer);
  2025.     av_freep(&s->bap1_buffer);
  2026.     av_freep(&s->mdct_coef_buffer);
  2027.     av_freep(&s->fixed_coef_buffer);
  2028.     av_freep(&s->exp_buffer);
  2029.     av_freep(&s->grouped_exp_buffer);
  2030.     av_freep(&s->psd_buffer);
  2031.     av_freep(&s->band_psd_buffer);
  2032.     av_freep(&s->mask_buffer);
  2033.     av_freep(&s->qmant_buffer);
  2034.     av_freep(&s->cpl_coord_exp_buffer);
  2035.     av_freep(&s->cpl_coord_mant_buffer);
  2036.     for (blk = 0; blk < s->num_blocks; blk++) {
  2037.         AC3Block *block = &s->blocks[blk];
  2038.         av_freep(&block->mdct_coef);
  2039.         av_freep(&block->fixed_coef);
  2040.         av_freep(&block->exp);
  2041.         av_freep(&block->grouped_exp);
  2042.         av_freep(&block->psd);
  2043.         av_freep(&block->band_psd);
  2044.         av_freep(&block->mask);
  2045.         av_freep(&block->qmant);
  2046.         av_freep(&block->cpl_coord_exp);
  2047.         av_freep(&block->cpl_coord_mant);
  2048.     }
  2049.  
  2050.     s->mdct_end(s);
  2051.  
  2052.     return 0;
  2053. }
  2054.  
  2055.  
  2056. /*
  2057.  * Set channel information during initialization.
  2058.  */
  2059. static av_cold int set_channel_info(AC3EncodeContext *s, int channels,
  2060.                                     uint64_t *channel_layout)
  2061. {
  2062.     int ch_layout;
  2063.  
  2064.     if (channels < 1 || channels > AC3_MAX_CHANNELS)
  2065.         return AVERROR(EINVAL);
  2066.     if (*channel_layout > 0x7FF)
  2067.         return AVERROR(EINVAL);
  2068.     ch_layout = *channel_layout;
  2069.     if (!ch_layout)
  2070.         ch_layout = av_get_default_channel_layout(channels);
  2071.  
  2072.     s->lfe_on       = !!(ch_layout & AV_CH_LOW_FREQUENCY);
  2073.     s->channels     = channels;
  2074.     s->fbw_channels = channels - s->lfe_on;
  2075.     s->lfe_channel  = s->lfe_on ? s->fbw_channels + 1 : -1;
  2076.     if (s->lfe_on)
  2077.         ch_layout -= AV_CH_LOW_FREQUENCY;
  2078.  
  2079.     switch (ch_layout) {
  2080.     case AV_CH_LAYOUT_MONO:           s->channel_mode = AC3_CHMODE_MONO;   break;
  2081.     case AV_CH_LAYOUT_STEREO:         s->channel_mode = AC3_CHMODE_STEREO; break;
  2082.     case AV_CH_LAYOUT_SURROUND:       s->channel_mode = AC3_CHMODE_3F;     break;
  2083.     case AV_CH_LAYOUT_2_1:            s->channel_mode = AC3_CHMODE_2F1R;   break;
  2084.     case AV_CH_LAYOUT_4POINT0:        s->channel_mode = AC3_CHMODE_3F1R;   break;
  2085.     case AV_CH_LAYOUT_QUAD:
  2086.     case AV_CH_LAYOUT_2_2:            s->channel_mode = AC3_CHMODE_2F2R;   break;
  2087.     case AV_CH_LAYOUT_5POINT0:
  2088.     case AV_CH_LAYOUT_5POINT0_BACK:   s->channel_mode = AC3_CHMODE_3F2R;   break;
  2089.     default:
  2090.         return AVERROR(EINVAL);
  2091.     }
  2092.     s->has_center   = (s->channel_mode & 0x01) && s->channel_mode != AC3_CHMODE_MONO;
  2093.     s->has_surround =  s->channel_mode & 0x04;
  2094.  
  2095.     s->channel_map  = ff_ac3_enc_channel_map[s->channel_mode][s->lfe_on];
  2096.     *channel_layout = ch_layout;
  2097.     if (s->lfe_on)
  2098.         *channel_layout |= AV_CH_LOW_FREQUENCY;
  2099.  
  2100.     return 0;
  2101. }
  2102.  
  2103.  
  2104. static av_cold int validate_options(AC3EncodeContext *s)
  2105. {
  2106.     AVCodecContext *avctx = s->avctx;
  2107.     int i, ret, max_sr;
  2108.  
  2109.     /* validate channel layout */
  2110.     if (!avctx->channel_layout) {
  2111.         av_log(avctx, AV_LOG_WARNING, "No channel layout specified. The "
  2112.                                       "encoder will guess the layout, but it "
  2113.                                       "might be incorrect.\n");
  2114.     }
  2115.     ret = set_channel_info(s, avctx->channels, &avctx->channel_layout);
  2116.     if (ret) {
  2117.         av_log(avctx, AV_LOG_ERROR, "invalid channel layout\n");
  2118.         return ret;
  2119.     }
  2120.  
  2121.     /* validate sample rate */
  2122.     /* note: max_sr could be changed from 2 to 5 for E-AC-3 once we find a
  2123.              decoder that supports half sample rate so we can validate that
  2124.              the generated files are correct. */
  2125.     max_sr = s->eac3 ? 2 : 8;
  2126.     for (i = 0; i <= max_sr; i++) {
  2127.         if ((ff_ac3_sample_rate_tab[i % 3] >> (i / 3)) == avctx->sample_rate)
  2128.             break;
  2129.     }
  2130.     if (i > max_sr) {
  2131.         av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n");
  2132.         return AVERROR(EINVAL);
  2133.     }
  2134.     s->sample_rate        = avctx->sample_rate;
  2135.     s->bit_alloc.sr_shift = i / 3;
  2136.     s->bit_alloc.sr_code  = i % 3;
  2137.     s->bitstream_id       = s->eac3 ? 16 : 8 + s->bit_alloc.sr_shift;
  2138.  
  2139.     /* select a default bit rate if not set by the user */
  2140.     if (!avctx->bit_rate) {
  2141.         switch (s->fbw_channels) {
  2142.         case 1: avctx->bit_rate =  96000; break;
  2143.         case 2: avctx->bit_rate = 192000; break;
  2144.         case 3: avctx->bit_rate = 320000; break;
  2145.         case 4: avctx->bit_rate = 384000; break;
  2146.         case 5: avctx->bit_rate = 448000; break;
  2147.         }
  2148.     }
  2149.  
  2150.     /* validate bit rate */
  2151.     if (s->eac3) {
  2152.         int max_br, min_br, wpf, min_br_dist, min_br_code;
  2153.         int num_blks_code, num_blocks, frame_samples;
  2154.  
  2155.         /* calculate min/max bitrate */
  2156.         /* TODO: More testing with 3 and 2 blocks. All E-AC-3 samples I've
  2157.                  found use either 6 blocks or 1 block, even though 2 or 3 blocks
  2158.                  would work as far as the bit rate is concerned. */
  2159.         for (num_blks_code = 3; num_blks_code >= 0; num_blks_code--) {
  2160.             num_blocks = ((int[]){ 1, 2, 3, 6 })[num_blks_code];
  2161.             frame_samples  = AC3_BLOCK_SIZE * num_blocks;
  2162.             max_br = 2048 * s->sample_rate / frame_samples * 16;
  2163.             min_br = ((s->sample_rate + (frame_samples-1)) / frame_samples) * 16;
  2164.             if (avctx->bit_rate <= max_br)
  2165.                 break;
  2166.         }
  2167.         if (avctx->bit_rate < min_br || avctx->bit_rate > max_br) {
  2168.             av_log(avctx, AV_LOG_ERROR, "invalid bit rate. must be %d to %d "
  2169.                    "for this sample rate\n", min_br, max_br);
  2170.             return AVERROR(EINVAL);
  2171.         }
  2172.         s->num_blks_code = num_blks_code;
  2173.         s->num_blocks    = num_blocks;
  2174.  
  2175.         /* calculate words-per-frame for the selected bitrate */
  2176.         wpf = (avctx->bit_rate / 16) * frame_samples / s->sample_rate;
  2177.         av_assert1(wpf > 0 && wpf <= 2048);
  2178.  
  2179.         /* find the closest AC-3 bitrate code to the selected bitrate.
  2180.            this is needed for lookup tables for bandwidth and coupling
  2181.            parameter selection */
  2182.         min_br_code = -1;
  2183.         min_br_dist = INT_MAX;
  2184.         for (i = 0; i < 19; i++) {
  2185.             int br_dist = abs(ff_ac3_bitrate_tab[i] * 1000 - avctx->bit_rate);
  2186.             if (br_dist < min_br_dist) {
  2187.                 min_br_dist = br_dist;
  2188.                 min_br_code = i;
  2189.             }
  2190.         }
  2191.  
  2192.         /* make sure the minimum frame size is below the average frame size */
  2193.         s->frame_size_code = min_br_code << 1;
  2194.         while (wpf > 1 && wpf * s->sample_rate / AC3_FRAME_SIZE * 16 > avctx->bit_rate)
  2195.             wpf--;
  2196.         s->frame_size_min = 2 * wpf;
  2197.     } else {
  2198.         int best_br = 0, best_code = 0, best_diff = INT_MAX;
  2199.         for (i = 0; i < 19; i++) {
  2200.             int br   = (ff_ac3_bitrate_tab[i] >> s->bit_alloc.sr_shift) * 1000;
  2201.             int diff = abs(br - avctx->bit_rate);
  2202.             if (diff < best_diff) {
  2203.                 best_br   = br;
  2204.                 best_code = i;
  2205.                 best_diff = diff;
  2206.             }
  2207.             if (!best_diff)
  2208.                 break;
  2209.         }
  2210.         avctx->bit_rate    = best_br;
  2211.         s->frame_size_code = best_code << 1;
  2212.         s->frame_size_min  = 2 * ff_ac3_frame_size_tab[s->frame_size_code][s->bit_alloc.sr_code];
  2213.         s->num_blks_code   = 0x3;
  2214.         s->num_blocks      = 6;
  2215.     }
  2216.     s->bit_rate   = avctx->bit_rate;
  2217.     s->frame_size = s->frame_size_min;
  2218.  
  2219.     /* validate cutoff */
  2220.     if (avctx->cutoff < 0) {
  2221.         av_log(avctx, AV_LOG_ERROR, "invalid cutoff frequency\n");
  2222.         return AVERROR(EINVAL);
  2223.     }
  2224.     s->cutoff = avctx->cutoff;
  2225.     if (s->cutoff > (s->sample_rate >> 1))
  2226.         s->cutoff = s->sample_rate >> 1;
  2227.  
  2228.     ret = ff_ac3_validate_metadata(s);
  2229.     if (ret)
  2230.         return ret;
  2231.  
  2232.     s->rematrixing_enabled = s->options.stereo_rematrixing &&
  2233.                              (s->channel_mode == AC3_CHMODE_STEREO);
  2234.  
  2235.     s->cpl_enabled = s->options.channel_coupling &&
  2236.                      s->channel_mode >= AC3_CHMODE_STEREO;
  2237.  
  2238.     return 0;
  2239. }
  2240.  
  2241.  
  2242. /*
  2243.  * Set bandwidth for all channels.
  2244.  * The user can optionally supply a cutoff frequency. Otherwise an appropriate
  2245.  * default value will be used.
  2246.  */
  2247. static av_cold void set_bandwidth(AC3EncodeContext *s)
  2248. {
  2249.     int blk, ch, cpl_start;
  2250.  
  2251.     if (s->cutoff) {
  2252.         /* calculate bandwidth based on user-specified cutoff frequency */
  2253.         int fbw_coeffs;
  2254.         fbw_coeffs     = s->cutoff * 2 * AC3_MAX_COEFS / s->sample_rate;
  2255.         s->bandwidth_code = av_clip((fbw_coeffs - 73) / 3, 0, 60);
  2256.     } else {
  2257.         /* use default bandwidth setting */
  2258.         s->bandwidth_code = ac3_bandwidth_tab[s->fbw_channels-1][s->bit_alloc.sr_code][s->frame_size_code/2];
  2259.     }
  2260.  
  2261.     /* set number of coefficients for each channel */
  2262.     for (ch = 1; ch <= s->fbw_channels; ch++) {
  2263.         s->start_freq[ch] = 0;
  2264.         for (blk = 0; blk < s->num_blocks; blk++)
  2265.             s->blocks[blk].end_freq[ch] = s->bandwidth_code * 3 + 73;
  2266.     }
  2267.     /* LFE channel always has 7 coefs */
  2268.     if (s->lfe_on) {
  2269.         s->start_freq[s->lfe_channel] = 0;
  2270.         for (blk = 0; blk < s->num_blocks; blk++)
  2271.             s->blocks[blk].end_freq[ch] = 7;
  2272.     }
  2273.  
  2274.     /* initialize coupling strategy */
  2275.     if (s->cpl_enabled) {
  2276.         if (s->options.cpl_start != AC3ENC_OPT_AUTO) {
  2277.             cpl_start = s->options.cpl_start;
  2278.         } else {
  2279.             cpl_start = ac3_coupling_start_tab[s->channel_mode-2][s->bit_alloc.sr_code][s->frame_size_code/2];
  2280.             if (cpl_start < 0) {
  2281.                 if (s->options.channel_coupling == AC3ENC_OPT_AUTO)
  2282.                     s->cpl_enabled = 0;
  2283.                 else
  2284.                     cpl_start = 15;
  2285.             }
  2286.         }
  2287.     }
  2288.     if (s->cpl_enabled) {
  2289.         int i, cpl_start_band, cpl_end_band;
  2290.         uint8_t *cpl_band_sizes = s->cpl_band_sizes;
  2291.  
  2292.         cpl_end_band   = s->bandwidth_code / 4 + 3;
  2293.         cpl_start_band = av_clip(cpl_start, 0, FFMIN(cpl_end_band-1, 15));
  2294.  
  2295.         s->num_cpl_subbands = cpl_end_band - cpl_start_band;
  2296.  
  2297.         s->num_cpl_bands = 1;
  2298.         *cpl_band_sizes  = 12;
  2299.         for (i = cpl_start_band + 1; i < cpl_end_band; i++) {
  2300.             if (ff_eac3_default_cpl_band_struct[i]) {
  2301.                 *cpl_band_sizes += 12;
  2302.             } else {
  2303.                 s->num_cpl_bands++;
  2304.                 cpl_band_sizes++;
  2305.                 *cpl_band_sizes = 12;
  2306.             }
  2307.         }
  2308.  
  2309.         s->start_freq[CPL_CH] = cpl_start_band * 12 + 37;
  2310.         s->cpl_end_freq       = cpl_end_band   * 12 + 37;
  2311.         for (blk = 0; blk < s->num_blocks; blk++)
  2312.             s->blocks[blk].end_freq[CPL_CH] = s->cpl_end_freq;
  2313.     }
  2314. }
  2315.  
  2316.  
  2317. static av_cold int allocate_buffers(AC3EncodeContext *s)
  2318. {
  2319.     AVCodecContext *avctx = s->avctx;
  2320.     int blk, ch;
  2321.     int channels = s->channels + 1; /* includes coupling channel */
  2322.     int channel_blocks = channels * s->num_blocks;
  2323.     int total_coefs    = AC3_MAX_COEFS * channel_blocks;
  2324.  
  2325.     if (s->allocate_sample_buffers(s))
  2326.         goto alloc_fail;
  2327.  
  2328.     FF_ALLOC_OR_GOTO(avctx, s->bap_buffer, total_coefs *
  2329.                      sizeof(*s->bap_buffer), alloc_fail);
  2330.     FF_ALLOC_OR_GOTO(avctx, s->bap1_buffer, total_coefs *
  2331.                      sizeof(*s->bap1_buffer), alloc_fail);
  2332.     FF_ALLOCZ_OR_GOTO(avctx, s->mdct_coef_buffer, total_coefs *
  2333.                       sizeof(*s->mdct_coef_buffer), alloc_fail);
  2334.     FF_ALLOC_OR_GOTO(avctx, s->exp_buffer, total_coefs *
  2335.                      sizeof(*s->exp_buffer), alloc_fail);
  2336.     FF_ALLOC_OR_GOTO(avctx, s->grouped_exp_buffer, channel_blocks * 128 *
  2337.                      sizeof(*s->grouped_exp_buffer), alloc_fail);
  2338.     FF_ALLOC_OR_GOTO(avctx, s->psd_buffer, total_coefs *
  2339.                      sizeof(*s->psd_buffer), alloc_fail);
  2340.     FF_ALLOC_OR_GOTO(avctx, s->band_psd_buffer, channel_blocks * 64 *
  2341.                      sizeof(*s->band_psd_buffer), alloc_fail);
  2342.     FF_ALLOC_OR_GOTO(avctx, s->mask_buffer, channel_blocks * 64 *
  2343.                      sizeof(*s->mask_buffer), alloc_fail);
  2344.     FF_ALLOC_OR_GOTO(avctx, s->qmant_buffer, total_coefs *
  2345.                      sizeof(*s->qmant_buffer), alloc_fail);
  2346.     if (s->cpl_enabled) {
  2347.         FF_ALLOC_OR_GOTO(avctx, s->cpl_coord_exp_buffer, channel_blocks * 16 *
  2348.                          sizeof(*s->cpl_coord_exp_buffer), alloc_fail);
  2349.         FF_ALLOC_OR_GOTO(avctx, s->cpl_coord_mant_buffer, channel_blocks * 16 *
  2350.                          sizeof(*s->cpl_coord_mant_buffer), alloc_fail);
  2351.     }
  2352.     for (blk = 0; blk < s->num_blocks; blk++) {
  2353.         AC3Block *block = &s->blocks[blk];
  2354.         FF_ALLOCZ_OR_GOTO(avctx, block->mdct_coef, channels * sizeof(*block->mdct_coef),
  2355.                           alloc_fail);
  2356.         FF_ALLOCZ_OR_GOTO(avctx, block->exp, channels * sizeof(*block->exp),
  2357.                           alloc_fail);
  2358.         FF_ALLOCZ_OR_GOTO(avctx, block->grouped_exp, channels * sizeof(*block->grouped_exp),
  2359.                           alloc_fail);
  2360.         FF_ALLOCZ_OR_GOTO(avctx, block->psd, channels * sizeof(*block->psd),
  2361.                           alloc_fail);
  2362.         FF_ALLOCZ_OR_GOTO(avctx, block->band_psd, channels * sizeof(*block->band_psd),
  2363.                           alloc_fail);
  2364.         FF_ALLOCZ_OR_GOTO(avctx, block->mask, channels * sizeof(*block->mask),
  2365.                           alloc_fail);
  2366.         FF_ALLOCZ_OR_GOTO(avctx, block->qmant, channels * sizeof(*block->qmant),
  2367.                           alloc_fail);
  2368.         if (s->cpl_enabled) {
  2369.             FF_ALLOCZ_OR_GOTO(avctx, block->cpl_coord_exp, channels * sizeof(*block->cpl_coord_exp),
  2370.                               alloc_fail);
  2371.             FF_ALLOCZ_OR_GOTO(avctx, block->cpl_coord_mant, channels * sizeof(*block->cpl_coord_mant),
  2372.                               alloc_fail);
  2373.         }
  2374.  
  2375.         for (ch = 0; ch < channels; ch++) {
  2376.             /* arrangement: block, channel, coeff */
  2377.             block->grouped_exp[ch] = &s->grouped_exp_buffer[128           * (blk * channels + ch)];
  2378.             block->psd[ch]         = &s->psd_buffer        [AC3_MAX_COEFS * (blk * channels + ch)];
  2379.             block->band_psd[ch]    = &s->band_psd_buffer   [64            * (blk * channels + ch)];
  2380.             block->mask[ch]        = &s->mask_buffer       [64            * (blk * channels + ch)];
  2381.             block->qmant[ch]       = &s->qmant_buffer      [AC3_MAX_COEFS * (blk * channels + ch)];
  2382.             if (s->cpl_enabled) {
  2383.                 block->cpl_coord_exp[ch]  = &s->cpl_coord_exp_buffer [16  * (blk * channels + ch)];
  2384.                 block->cpl_coord_mant[ch] = &s->cpl_coord_mant_buffer[16  * (blk * channels + ch)];
  2385.             }
  2386.  
  2387.             /* arrangement: channel, block, coeff */
  2388.             block->exp[ch]         = &s->exp_buffer        [AC3_MAX_COEFS * (s->num_blocks * ch + blk)];
  2389.             block->mdct_coef[ch]   = &s->mdct_coef_buffer  [AC3_MAX_COEFS * (s->num_blocks * ch + blk)];
  2390.         }
  2391.     }
  2392.  
  2393.     if (!s->fixed_point) {
  2394.         FF_ALLOCZ_OR_GOTO(avctx, s->fixed_coef_buffer, total_coefs *
  2395.                           sizeof(*s->fixed_coef_buffer), alloc_fail);
  2396.         for (blk = 0; blk < s->num_blocks; blk++) {
  2397.             AC3Block *block = &s->blocks[blk];
  2398.             FF_ALLOCZ_OR_GOTO(avctx, block->fixed_coef, channels *
  2399.                               sizeof(*block->fixed_coef), alloc_fail);
  2400.             for (ch = 0; ch < channels; ch++)
  2401.                 block->fixed_coef[ch] = &s->fixed_coef_buffer[AC3_MAX_COEFS * (s->num_blocks * ch + blk)];
  2402.         }
  2403.     } else {
  2404.         for (blk = 0; blk < s->num_blocks; blk++) {
  2405.             AC3Block *block = &s->blocks[blk];
  2406.             FF_ALLOCZ_OR_GOTO(avctx, block->fixed_coef, channels *
  2407.                               sizeof(*block->fixed_coef), alloc_fail);
  2408.             for (ch = 0; ch < channels; ch++)
  2409.                 block->fixed_coef[ch] = (int32_t *)block->mdct_coef[ch];
  2410.         }
  2411.     }
  2412.  
  2413.     return 0;
  2414. alloc_fail:
  2415.     return AVERROR(ENOMEM);
  2416. }
  2417.  
  2418.  
  2419. av_cold int ff_ac3_encode_init(AVCodecContext *avctx)
  2420. {
  2421.     AC3EncodeContext *s = avctx->priv_data;
  2422.     int ret, frame_size_58;
  2423.  
  2424.     s->avctx = avctx;
  2425.  
  2426.     s->eac3 = avctx->codec_id == AV_CODEC_ID_EAC3;
  2427.  
  2428.     ff_ac3_common_init();
  2429.  
  2430.     ret = validate_options(s);
  2431.     if (ret)
  2432.         return ret;
  2433.  
  2434.     avctx->frame_size = AC3_BLOCK_SIZE * s->num_blocks;
  2435.     avctx->delay      = AC3_BLOCK_SIZE;
  2436.  
  2437.     s->bitstream_mode = avctx->audio_service_type;
  2438.     if (s->bitstream_mode == AV_AUDIO_SERVICE_TYPE_KARAOKE)
  2439.         s->bitstream_mode = 0x7;
  2440.  
  2441.     s->bits_written    = 0;
  2442.     s->samples_written = 0;
  2443.  
  2444.     /* calculate crc_inv for both possible frame sizes */
  2445.     frame_size_58 = (( s->frame_size    >> 2) + ( s->frame_size    >> 4)) << 1;
  2446.     s->crc_inv[0] = pow_poly((CRC16_POLY >> 1), (8 * frame_size_58) - 16, CRC16_POLY);
  2447.     if (s->bit_alloc.sr_code == 1) {
  2448.         frame_size_58 = (((s->frame_size+2) >> 2) + ((s->frame_size+2) >> 4)) << 1;
  2449.         s->crc_inv[1] = pow_poly((CRC16_POLY >> 1), (8 * frame_size_58) - 16, CRC16_POLY);
  2450.     }
  2451.  
  2452.     /* set function pointers */
  2453.     if (CONFIG_AC3_FIXED_ENCODER && s->fixed_point) {
  2454.         s->mdct_end                     = ff_ac3_fixed_mdct_end;
  2455.         s->mdct_init                    = ff_ac3_fixed_mdct_init;
  2456.         s->allocate_sample_buffers      = ff_ac3_fixed_allocate_sample_buffers;
  2457.     } else if (CONFIG_AC3_ENCODER || CONFIG_EAC3_ENCODER) {
  2458.         s->mdct_end                     = ff_ac3_float_mdct_end;
  2459.         s->mdct_init                    = ff_ac3_float_mdct_init;
  2460.         s->allocate_sample_buffers      = ff_ac3_float_allocate_sample_buffers;
  2461.     }
  2462.     if (CONFIG_EAC3_ENCODER && s->eac3)
  2463.         s->output_frame_header = ff_eac3_output_frame_header;
  2464.     else
  2465.         s->output_frame_header = ac3_output_frame_header;
  2466.  
  2467.     set_bandwidth(s);
  2468.  
  2469.     exponent_init(s);
  2470.  
  2471.     bit_alloc_init(s);
  2472.  
  2473.     ret = s->mdct_init(s);
  2474.     if (ret)
  2475.         goto init_fail;
  2476.  
  2477.     ret = allocate_buffers(s);
  2478.     if (ret)
  2479.         goto init_fail;
  2480.  
  2481.     ff_dsputil_init(&s->dsp, avctx);
  2482.     avpriv_float_dsp_init(&s->fdsp, avctx->flags & CODEC_FLAG_BITEXACT);
  2483.     ff_ac3dsp_init(&s->ac3dsp, avctx->flags & CODEC_FLAG_BITEXACT);
  2484.  
  2485.     dprint_options(s);
  2486.  
  2487.     return 0;
  2488. init_fail:
  2489.     ff_ac3_encode_close(avctx);
  2490.     return ret;
  2491. }
  2492.