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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 "internal.h"
  40. #include "me_cmp.h"
  41. #include "put_bits.h"
  42. #include "audiodsp.h"
  43. #include "ac3dsp.h"
  44. #include "ac3.h"
  45. #include "fft.h"
  46. #include "ac3enc.h"
  47. #include "eac3enc.h"
  48.  
  49. typedef struct AC3Mant {
  50.     int16_t *qmant1_ptr, *qmant2_ptr, *qmant4_ptr; ///< mantissa pointers for bap=1,2,4
  51.     int mant1_cnt, mant2_cnt, mant4_cnt;    ///< mantissa counts for bap=1,2,4
  52. } AC3Mant;
  53.  
  54. #define CMIXLEV_NUM_OPTIONS 3
  55. static const float cmixlev_options[CMIXLEV_NUM_OPTIONS] = {
  56.     LEVEL_MINUS_3DB, LEVEL_MINUS_4POINT5DB, LEVEL_MINUS_6DB
  57. };
  58.  
  59. #define SURMIXLEV_NUM_OPTIONS 3
  60. static const float surmixlev_options[SURMIXLEV_NUM_OPTIONS] = {
  61.     LEVEL_MINUS_3DB, LEVEL_MINUS_6DB, LEVEL_ZERO
  62. };
  63.  
  64. #define EXTMIXLEV_NUM_OPTIONS 8
  65. static const float extmixlev_options[EXTMIXLEV_NUM_OPTIONS] = {
  66.     LEVEL_PLUS_3DB,  LEVEL_PLUS_1POINT5DB,  LEVEL_ONE,       LEVEL_MINUS_4POINT5DB,
  67.     LEVEL_MINUS_3DB, LEVEL_MINUS_4POINT5DB, LEVEL_MINUS_6DB, LEVEL_ZERO
  68. };
  69.  
  70.  
  71. /**
  72.  * LUT for number of exponent groups.
  73.  * exponent_group_tab[coupling][exponent strategy-1][number of coefficients]
  74.  */
  75. static uint8_t exponent_group_tab[2][3][256];
  76.  
  77.  
  78. /**
  79.  * List of supported channel layouts.
  80.  */
  81. const uint64_t ff_ac3_channel_layouts[19] = {
  82.      AV_CH_LAYOUT_MONO,
  83.      AV_CH_LAYOUT_STEREO,
  84.      AV_CH_LAYOUT_2_1,
  85.      AV_CH_LAYOUT_SURROUND,
  86.      AV_CH_LAYOUT_2_2,
  87.      AV_CH_LAYOUT_QUAD,
  88.      AV_CH_LAYOUT_4POINT0,
  89.      AV_CH_LAYOUT_5POINT0,
  90.      AV_CH_LAYOUT_5POINT0_BACK,
  91.     (AV_CH_LAYOUT_MONO     | AV_CH_LOW_FREQUENCY),
  92.     (AV_CH_LAYOUT_STEREO   | AV_CH_LOW_FREQUENCY),
  93.     (AV_CH_LAYOUT_2_1      | AV_CH_LOW_FREQUENCY),
  94.     (AV_CH_LAYOUT_SURROUND | AV_CH_LOW_FREQUENCY),
  95.     (AV_CH_LAYOUT_2_2      | AV_CH_LOW_FREQUENCY),
  96.     (AV_CH_LAYOUT_QUAD     | AV_CH_LOW_FREQUENCY),
  97.     (AV_CH_LAYOUT_4POINT0  | AV_CH_LOW_FREQUENCY),
  98.      AV_CH_LAYOUT_5POINT1,
  99.      AV_CH_LAYOUT_5POINT1_BACK,
  100.      0
  101. };
  102.  
  103.  
  104. /**
  105.  * LUT to select the bandwidth code based on the bit rate, sample rate, and
  106.  * number of full-bandwidth channels.
  107.  * bandwidth_tab[fbw_channels-1][sample rate code][bit rate code]
  108.  */
  109. static const uint8_t ac3_bandwidth_tab[5][3][19] = {
  110. //      32  40  48  56  64  80  96 112 128 160 192 224 256 320 384 448 512 576 640
  111.  
  112.     { {  0,  0,  0, 12, 16, 32, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48 },
  113.       {  0,  0,  0, 16, 20, 36, 56, 56, 56, 56, 56, 56, 56, 56, 56, 56, 56, 56, 56 },
  114.       {  0,  0,  0, 32, 40, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60 } },
  115.  
  116.     { {  0,  0,  0,  0,  0,  0,  0, 20, 24, 32, 48, 48, 48, 48, 48, 48, 48, 48, 48 },
  117.       {  0,  0,  0,  0,  0,  0,  4, 24, 28, 36, 56, 56, 56, 56, 56, 56, 56, 56, 56 },
  118.       {  0,  0,  0,  0,  0,  0, 20, 44, 52, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60 } },
  119.  
  120.     { {  0,  0,  0,  0,  0,  0,  0,  0,  0, 16, 24, 32, 40, 48, 48, 48, 48, 48, 48 },
  121.       {  0,  0,  0,  0,  0,  0,  0,  0,  4, 20, 28, 36, 44, 56, 56, 56, 56, 56, 56 },
  122.       {  0,  0,  0,  0,  0,  0,  0,  0, 20, 40, 48, 60, 60, 60, 60, 60, 60, 60, 60 } },
  123.  
  124.     { {  0,  0,  0,  0,  0,  0,  0,  0,  0,  0, 12, 24, 32, 48, 48, 48, 48, 48, 48 },
  125.       {  0,  0,  0,  0,  0,  0,  0,  0,  0,  0, 16, 28, 36, 56, 56, 56, 56, 56, 56 },
  126.       {  0,  0,  0,  0,  0,  0,  0,  0,  0,  0, 32, 48, 60, 60, 60, 60, 60, 60, 60 } },
  127.  
  128.     { {  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  8, 20, 32, 40, 48, 48, 48, 48 },
  129.       {  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0, 12, 24, 36, 44, 56, 56, 56, 56 },
  130.       {  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0, 28, 44, 60, 60, 60, 60, 60, 60 } }
  131. };
  132.  
  133.  
  134. /**
  135.  * LUT to select the coupling start band based on the bit rate, sample rate, and
  136.  * number of full-bandwidth channels. -1 = coupling off
  137.  * ac3_coupling_start_tab[channel_mode-2][sample rate code][bit rate code]
  138.  *
  139.  * TODO: more testing for optimal parameters.
  140.  *       multi-channel tests at 44.1kHz and 32kHz.
  141.  */
  142. static const int8_t ac3_coupling_start_tab[6][3][19] = {
  143. //      32  40  48  56  64  80  96 112 128 160 192 224 256 320 384 448 512 576 640
  144.  
  145.     // 2/0
  146.     { {  0,  0,  0,  0,  0,  0,  0,  1,  1,  7,  8, 11, 12, -1, -1, -1, -1, -1, -1 },
  147.       {  0,  0,  0,  0,  0,  0,  1,  3,  5,  7, 10, 12, 13, -1, -1, -1, -1, -1, -1 },
  148.       {  0,  0,  0,  0,  1,  2,  2,  9, 13, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1 } },
  149.  
  150.     // 3/0
  151.     { {  0,  0,  0,  0,  0,  0,  0,  0,  2,  2,  6,  9, 11, 12, 13, -1, -1, -1, -1 },
  152.       {  0,  0,  0,  0,  0,  0,  0,  0,  2,  2,  6,  9, 11, 12, 13, -1, -1, -1, -1 },
  153.       { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 } },
  154.  
  155.     // 2/1 - untested
  156.     { {  0,  0,  0,  0,  0,  0,  0,  0,  2,  2,  6,  9, 11, 12, 13, -1, -1, -1, -1 },
  157.       {  0,  0,  0,  0,  0,  0,  0,  0,  2,  2,  6,  9, 11, 12, 13, -1, -1, -1, -1 },
  158.       { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 } },
  159.  
  160.     // 3/1
  161.     { {  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  3,  2, 10, 11, 11, 12, 12, 14, -1 },
  162.       {  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  3,  2, 10, 11, 11, 12, 12, 14, -1 },
  163.       { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 } },
  164.  
  165.     // 2/2 - untested
  166.     { {  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  3,  2, 10, 11, 11, 12, 12, 14, -1 },
  167.       {  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  3,  2, 10, 11, 11, 12, 12, 14, -1 },
  168.       { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 } },
  169.  
  170.     // 3/2
  171.     { {  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  1,  6,  8, 11, 12, 12, -1, -1 },
  172.       {  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  1,  6,  8, 11, 12, 12, -1, -1 },
  173.       { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 } },
  174. };
  175.  
  176.  
  177. /**
  178.  * Adjust the frame size to make the average bit rate match the target bit rate.
  179.  * This is only needed for 11025, 22050, and 44100 sample rates or any E-AC-3.
  180.  *
  181.  * @param s  AC-3 encoder private context
  182.  */
  183. void ff_ac3_adjust_frame_size(AC3EncodeContext *s)
  184. {
  185.     while (s->bits_written >= s->bit_rate && s->samples_written >= s->sample_rate) {
  186.         s->bits_written    -= s->bit_rate;
  187.         s->samples_written -= s->sample_rate;
  188.     }
  189.     s->frame_size = s->frame_size_min +
  190.                     2 * (s->bits_written * s->sample_rate < s->samples_written * s->bit_rate);
  191.     s->bits_written    += s->frame_size * 8;
  192.     s->samples_written += AC3_BLOCK_SIZE * s->num_blocks;
  193. }
  194.  
  195.  
  196. /**
  197.  * Set the initial coupling strategy parameters prior to coupling analysis.
  198.  *
  199.  * @param s  AC-3 encoder private context
  200.  */
  201. void ff_ac3_compute_coupling_strategy(AC3EncodeContext *s)
  202. {
  203.     int blk, ch;
  204.     int got_cpl_snr;
  205.     int num_cpl_blocks;
  206.  
  207.     /* set coupling use flags for each block/channel */
  208.     /* TODO: turn coupling on/off and adjust start band based on bit usage */
  209.     for (blk = 0; blk < s->num_blocks; blk++) {
  210.         AC3Block *block = &s->blocks[blk];
  211.         for (ch = 1; ch <= s->fbw_channels; ch++)
  212.             block->channel_in_cpl[ch] = s->cpl_on;
  213.     }
  214.  
  215.     /* enable coupling for each block if at least 2 channels have coupling
  216.        enabled for that block */
  217.     got_cpl_snr = 0;
  218.     num_cpl_blocks = 0;
  219.     for (blk = 0; blk < s->num_blocks; blk++) {
  220.         AC3Block *block = &s->blocks[blk];
  221.         block->num_cpl_channels = 0;
  222.         for (ch = 1; ch <= s->fbw_channels; ch++)
  223.             block->num_cpl_channels += block->channel_in_cpl[ch];
  224.         block->cpl_in_use = block->num_cpl_channels > 1;
  225.         num_cpl_blocks += block->cpl_in_use;
  226.         if (!block->cpl_in_use) {
  227.             block->num_cpl_channels = 0;
  228.             for (ch = 1; ch <= s->fbw_channels; ch++)
  229.                 block->channel_in_cpl[ch] = 0;
  230.         }
  231.  
  232.         block->new_cpl_strategy = !blk;
  233.         if (blk) {
  234.             for (ch = 1; ch <= s->fbw_channels; ch++) {
  235.                 if (block->channel_in_cpl[ch] != s->blocks[blk-1].channel_in_cpl[ch]) {
  236.                     block->new_cpl_strategy = 1;
  237.                     break;
  238.                 }
  239.             }
  240.         }
  241.         block->new_cpl_leak = block->new_cpl_strategy;
  242.  
  243.         if (!blk || (block->cpl_in_use && !got_cpl_snr)) {
  244.             block->new_snr_offsets = 1;
  245.             if (block->cpl_in_use)
  246.                 got_cpl_snr = 1;
  247.         } else {
  248.             block->new_snr_offsets = 0;
  249.         }
  250.     }
  251.     if (!num_cpl_blocks)
  252.         s->cpl_on = 0;
  253.  
  254.     /* set bandwidth for each channel */
  255.     for (blk = 0; blk < s->num_blocks; blk++) {
  256.         AC3Block *block = &s->blocks[blk];
  257.         for (ch = 1; ch <= s->fbw_channels; ch++) {
  258.             if (block->channel_in_cpl[ch])
  259.                 block->end_freq[ch] = s->start_freq[CPL_CH];
  260.             else
  261.                 block->end_freq[ch] = s->bandwidth_code * 3 + 73;
  262.         }
  263.     }
  264. }
  265.  
  266.  
  267. /**
  268.  * Apply stereo rematrixing to coefficients based on rematrixing flags.
  269.  *
  270.  * @param s  AC-3 encoder private context
  271.  */
  272. void ff_ac3_apply_rematrixing(AC3EncodeContext *s)
  273. {
  274.     int nb_coefs;
  275.     int blk, bnd, i;
  276.     int start, end;
  277.     uint8_t *flags = NULL;
  278.  
  279.     if (!s->rematrixing_enabled)
  280.         return;
  281.  
  282.     for (blk = 0; blk < s->num_blocks; blk++) {
  283.         AC3Block *block = &s->blocks[blk];
  284.         if (block->new_rematrixing_strategy)
  285.             flags = block->rematrixing_flags;
  286.         nb_coefs = FFMIN(block->end_freq[1], block->end_freq[2]);
  287.         for (bnd = 0; bnd < block->num_rematrixing_bands; bnd++) {
  288.             if (flags[bnd]) {
  289.                 start = ff_ac3_rematrix_band_tab[bnd];
  290.                 end   = FFMIN(nb_coefs, ff_ac3_rematrix_band_tab[bnd+1]);
  291.                 for (i = start; i < end; i++) {
  292.                     int32_t lt = block->fixed_coef[1][i];
  293.                     int32_t rt = block->fixed_coef[2][i];
  294.                     block->fixed_coef[1][i] = (lt + rt) >> 1;
  295.                     block->fixed_coef[2][i] = (lt - rt) >> 1;
  296.                 }
  297.             }
  298.         }
  299.     }
  300. }
  301.  
  302.  
  303. /*
  304.  * Initialize exponent tables.
  305.  */
  306. static av_cold void exponent_init(AC3EncodeContext *s)
  307. {
  308.     int expstr, i, grpsize;
  309.  
  310.     for (expstr = EXP_D15-1; expstr <= EXP_D45-1; expstr++) {
  311.         grpsize = 3 << expstr;
  312.         for (i = 12; i < 256; i++) {
  313.             exponent_group_tab[0][expstr][i] = (i + grpsize - 4) / grpsize;
  314.             exponent_group_tab[1][expstr][i] = (i              ) / grpsize;
  315.         }
  316.     }
  317.     /* LFE */
  318.     exponent_group_tab[0][0][7] = 2;
  319.  
  320.     if (CONFIG_EAC3_ENCODER && s->eac3)
  321.         ff_eac3_exponent_init();
  322. }
  323.  
  324.  
  325. /*
  326.  * Extract exponents from the MDCT coefficients.
  327.  */
  328. static void extract_exponents(AC3EncodeContext *s)
  329. {
  330.     int ch        = !s->cpl_on;
  331.     int chan_size = AC3_MAX_COEFS * s->num_blocks * (s->channels - ch + 1);
  332.     AC3Block *block = &s->blocks[0];
  333.  
  334.     s->ac3dsp.extract_exponents(block->exp[ch], block->fixed_coef[ch], chan_size);
  335. }
  336.  
  337.  
  338. /**
  339.  * Exponent Difference Threshold.
  340.  * New exponents are sent if their SAD exceed this number.
  341.  */
  342. #define EXP_DIFF_THRESHOLD 500
  343.  
  344. /**
  345.  * Table used to select exponent strategy based on exponent reuse block interval.
  346.  */
  347. static const uint8_t exp_strategy_reuse_tab[4][6] = {
  348.     { EXP_D15, EXP_D15, EXP_D15, EXP_D15, EXP_D15, EXP_D15 },
  349.     { EXP_D15, EXP_D15, EXP_D15, EXP_D15, EXP_D15, EXP_D15 },
  350.     { EXP_D25, EXP_D25, EXP_D15, EXP_D15, EXP_D15, EXP_D15 },
  351.     { EXP_D45, EXP_D25, EXP_D25, EXP_D15, EXP_D15, EXP_D15 }
  352. };
  353.  
  354. /*
  355.  * Calculate exponent strategies for all channels.
  356.  * Array arrangement is reversed to simplify the per-channel calculation.
  357.  */
  358. static void compute_exp_strategy(AC3EncodeContext *s)
  359. {
  360.     int ch, blk, blk1;
  361.  
  362.     for (ch = !s->cpl_on; ch <= s->fbw_channels; ch++) {
  363.         uint8_t *exp_strategy = s->exp_strategy[ch];
  364.         uint8_t *exp          = s->blocks[0].exp[ch];
  365.         int exp_diff;
  366.  
  367.         /* estimate if the exponent variation & decide if they should be
  368.            reused in the next frame */
  369.         exp_strategy[0] = EXP_NEW;
  370.         exp += AC3_MAX_COEFS;
  371.         for (blk = 1; blk < s->num_blocks; blk++, exp += AC3_MAX_COEFS) {
  372.             if (ch == CPL_CH) {
  373.                 if (!s->blocks[blk-1].cpl_in_use) {
  374.                     exp_strategy[blk] = EXP_NEW;
  375.                     continue;
  376.                 } else if (!s->blocks[blk].cpl_in_use) {
  377.                     exp_strategy[blk] = EXP_REUSE;
  378.                     continue;
  379.                 }
  380.             } else if (s->blocks[blk].channel_in_cpl[ch] != s->blocks[blk-1].channel_in_cpl[ch]) {
  381.                 exp_strategy[blk] = EXP_NEW;
  382.                 continue;
  383.             }
  384.             exp_diff = s->mecc.sad[0](NULL, exp, exp - AC3_MAX_COEFS, 16, 16);
  385.             exp_strategy[blk] = EXP_REUSE;
  386.             if (ch == CPL_CH && exp_diff > (EXP_DIFF_THRESHOLD * (s->blocks[blk].end_freq[ch] - s->start_freq[ch]) / AC3_MAX_COEFS))
  387.                 exp_strategy[blk] = EXP_NEW;
  388.             else if (ch > CPL_CH && exp_diff > EXP_DIFF_THRESHOLD)
  389.                 exp_strategy[blk] = EXP_NEW;
  390.         }
  391.  
  392.         /* now select the encoding strategy type : if exponents are often
  393.            recoded, we use a coarse encoding */
  394.         blk = 0;
  395.         while (blk < s->num_blocks) {
  396.             blk1 = blk + 1;
  397.             while (blk1 < s->num_blocks && exp_strategy[blk1] == EXP_REUSE)
  398.                 blk1++;
  399.             exp_strategy[blk] = exp_strategy_reuse_tab[s->num_blks_code][blk1-blk-1];
  400.             blk = blk1;
  401.         }
  402.     }
  403.     if (s->lfe_on) {
  404.         ch = s->lfe_channel;
  405.         s->exp_strategy[ch][0] = EXP_D15;
  406.         for (blk = 1; blk < s->num_blocks; blk++)
  407.             s->exp_strategy[ch][blk] = EXP_REUSE;
  408.     }
  409.  
  410.     /* for E-AC-3, determine frame exponent strategy */
  411.     if (CONFIG_EAC3_ENCODER && s->eac3)
  412.         ff_eac3_get_frame_exp_strategy(s);
  413. }
  414.  
  415.  
  416. /**
  417.  * Update the exponents so that they are the ones the decoder will decode.
  418.  *
  419.  * @param[in,out] exp   array of exponents for 1 block in 1 channel
  420.  * @param nb_exps       number of exponents in active bandwidth
  421.  * @param exp_strategy  exponent strategy for the block
  422.  * @param cpl           indicates if the block is in the coupling channel
  423.  */
  424. static void encode_exponents_blk_ch(uint8_t *exp, int nb_exps, int exp_strategy,
  425.                                     int cpl)
  426. {
  427.     int nb_groups, i, k;
  428.  
  429.     nb_groups = exponent_group_tab[cpl][exp_strategy-1][nb_exps] * 3;
  430.  
  431.     /* for each group, compute the minimum exponent */
  432.     switch(exp_strategy) {
  433.     case EXP_D25:
  434.         for (i = 1, k = 1-cpl; i <= nb_groups; i++) {
  435.             uint8_t exp_min = exp[k];
  436.             if (exp[k+1] < exp_min)
  437.                 exp_min = exp[k+1];
  438.             exp[i-cpl] = exp_min;
  439.             k += 2;
  440.         }
  441.         break;
  442.     case EXP_D45:
  443.         for (i = 1, k = 1-cpl; i <= nb_groups; i++) {
  444.             uint8_t exp_min = exp[k];
  445.             if (exp[k+1] < exp_min)
  446.                 exp_min = exp[k+1];
  447.             if (exp[k+2] < exp_min)
  448.                 exp_min = exp[k+2];
  449.             if (exp[k+3] < exp_min)
  450.                 exp_min = exp[k+3];
  451.             exp[i-cpl] = exp_min;
  452.             k += 4;
  453.         }
  454.         break;
  455.     }
  456.  
  457.     /* constraint for DC exponent */
  458.     if (!cpl && exp[0] > 15)
  459.         exp[0] = 15;
  460.  
  461.     /* decrease the delta between each groups to within 2 so that they can be
  462.        differentially encoded */
  463.     for (i = 1; i <= nb_groups; i++)
  464.         exp[i] = FFMIN(exp[i], exp[i-1] + 2);
  465.     i--;
  466.     while (--i >= 0)
  467.         exp[i] = FFMIN(exp[i], exp[i+1] + 2);
  468.  
  469.     if (cpl)
  470.         exp[-1] = exp[0] & ~1;
  471.  
  472.     /* now we have the exponent values the decoder will see */
  473.     switch (exp_strategy) {
  474.     case EXP_D25:
  475.         for (i = nb_groups, k = (nb_groups * 2)-cpl; i > 0; i--) {
  476.             uint8_t exp1 = exp[i-cpl];
  477.             exp[k--] = exp1;
  478.             exp[k--] = exp1;
  479.         }
  480.         break;
  481.     case EXP_D45:
  482.         for (i = nb_groups, k = (nb_groups * 4)-cpl; i > 0; i--) {
  483.             exp[k] = exp[k-1] = exp[k-2] = exp[k-3] = exp[i-cpl];
  484.             k -= 4;
  485.         }
  486.         break;
  487.     }
  488. }
  489.  
  490.  
  491. /*
  492.  * Encode exponents from original extracted form to what the decoder will see.
  493.  * This copies and groups exponents based on exponent strategy and reduces
  494.  * deltas between adjacent exponent groups so that they can be differentially
  495.  * encoded.
  496.  */
  497. static void encode_exponents(AC3EncodeContext *s)
  498. {
  499.     int blk, blk1, ch, cpl;
  500.     uint8_t *exp, *exp_strategy;
  501.     int nb_coefs, num_reuse_blocks;
  502.  
  503.     for (ch = !s->cpl_on; ch <= s->channels; ch++) {
  504.         exp          = s->blocks[0].exp[ch] + s->start_freq[ch];
  505.         exp_strategy = s->exp_strategy[ch];
  506.  
  507.         cpl = (ch == CPL_CH);
  508.         blk = 0;
  509.         while (blk < s->num_blocks) {
  510.             AC3Block *block = &s->blocks[blk];
  511.             if (cpl && !block->cpl_in_use) {
  512.                 exp += AC3_MAX_COEFS;
  513.                 blk++;
  514.                 continue;
  515.             }
  516.             nb_coefs = block->end_freq[ch] - s->start_freq[ch];
  517.             blk1 = blk + 1;
  518.  
  519.             /* count the number of EXP_REUSE blocks after the current block
  520.                and set exponent reference block numbers */
  521.             s->exp_ref_block[ch][blk] = blk;
  522.             while (blk1 < s->num_blocks && exp_strategy[blk1] == EXP_REUSE) {
  523.                 s->exp_ref_block[ch][blk1] = blk;
  524.                 blk1++;
  525.             }
  526.             num_reuse_blocks = blk1 - blk - 1;
  527.  
  528.             /* for the EXP_REUSE case we select the min of the exponents */
  529.             s->ac3dsp.ac3_exponent_min(exp-s->start_freq[ch], num_reuse_blocks,
  530.                                        AC3_MAX_COEFS);
  531.  
  532.             encode_exponents_blk_ch(exp, nb_coefs, exp_strategy[blk], cpl);
  533.  
  534.             exp += AC3_MAX_COEFS * (num_reuse_blocks + 1);
  535.             blk = blk1;
  536.         }
  537.     }
  538.  
  539.     /* reference block numbers have been changed, so reset ref_bap_set */
  540.     s->ref_bap_set = 0;
  541. }
  542.  
  543.  
  544. /*
  545.  * Count exponent bits based on bandwidth, coupling, and exponent strategies.
  546.  */
  547. static int count_exponent_bits(AC3EncodeContext *s)
  548. {
  549.     int blk, ch;
  550.     int nb_groups, bit_count;
  551.  
  552.     bit_count = 0;
  553.     for (blk = 0; blk < s->num_blocks; blk++) {
  554.         AC3Block *block = &s->blocks[blk];
  555.         for (ch = !block->cpl_in_use; ch <= s->channels; ch++) {
  556.             int exp_strategy = s->exp_strategy[ch][blk];
  557.             int cpl          = (ch == CPL_CH);
  558.             int nb_coefs     = block->end_freq[ch] - s->start_freq[ch];
  559.  
  560.             if (exp_strategy == EXP_REUSE)
  561.                 continue;
  562.  
  563.             nb_groups = exponent_group_tab[cpl][exp_strategy-1][nb_coefs];
  564.             bit_count += 4 + (nb_groups * 7);
  565.         }
  566.     }
  567.  
  568.     return bit_count;
  569. }
  570.  
  571.  
  572. /**
  573.  * Group exponents.
  574.  * 3 delta-encoded exponents are in each 7-bit group. The number of groups
  575.  * varies depending on exponent strategy and bandwidth.
  576.  *
  577.  * @param s  AC-3 encoder private context
  578.  */
  579. void ff_ac3_group_exponents(AC3EncodeContext *s)
  580. {
  581.     int blk, ch, i, cpl;
  582.     int group_size, nb_groups;
  583.     uint8_t *p;
  584.     int delta0, delta1, delta2;
  585.     int exp0, exp1;
  586.  
  587.     for (blk = 0; blk < s->num_blocks; blk++) {
  588.         AC3Block *block = &s->blocks[blk];
  589.         for (ch = !block->cpl_in_use; ch <= s->channels; ch++) {
  590.             int exp_strategy = s->exp_strategy[ch][blk];
  591.             if (exp_strategy == EXP_REUSE)
  592.                 continue;
  593.             cpl = (ch == CPL_CH);
  594.             group_size = exp_strategy + (exp_strategy == EXP_D45);
  595.             nb_groups = exponent_group_tab[cpl][exp_strategy-1][block->end_freq[ch]-s->start_freq[ch]];
  596.             p = block->exp[ch] + s->start_freq[ch] - cpl;
  597.  
  598.             /* DC exponent */
  599.             exp1 = *p++;
  600.             block->grouped_exp[ch][0] = exp1;
  601.  
  602.             /* remaining exponents are delta encoded */
  603.             for (i = 1; i <= nb_groups; i++) {
  604.                 /* merge three delta in one code */
  605.                 exp0   = exp1;
  606.                 exp1   = p[0];
  607.                 p     += group_size;
  608.                 delta0 = exp1 - exp0 + 2;
  609.                 av_assert2(delta0 >= 0 && delta0 <= 4);
  610.  
  611.                 exp0   = exp1;
  612.                 exp1   = p[0];
  613.                 p     += group_size;
  614.                 delta1 = exp1 - exp0 + 2;
  615.                 av_assert2(delta1 >= 0 && delta1 <= 4);
  616.  
  617.                 exp0   = exp1;
  618.                 exp1   = p[0];
  619.                 p     += group_size;
  620.                 delta2 = exp1 - exp0 + 2;
  621.                 av_assert2(delta2 >= 0 && delta2 <= 4);
  622.  
  623.                 block->grouped_exp[ch][i] = ((delta0 * 5 + delta1) * 5) + delta2;
  624.             }
  625.         }
  626.     }
  627. }
  628.  
  629.  
  630. /**
  631.  * Calculate final exponents from the supplied MDCT coefficients and exponent shift.
  632.  * Extract exponents from MDCT coefficients, calculate exponent strategies,
  633.  * and encode final exponents.
  634.  *
  635.  * @param s  AC-3 encoder private context
  636.  */
  637. void ff_ac3_process_exponents(AC3EncodeContext *s)
  638. {
  639.     extract_exponents(s);
  640.  
  641.     compute_exp_strategy(s);
  642.  
  643.     encode_exponents(s);
  644.  
  645.     emms_c();
  646. }
  647.  
  648.  
  649. /*
  650.  * Count frame bits that are based solely on fixed parameters.
  651.  * This only has to be run once when the encoder is initialized.
  652.  */
  653. static void count_frame_bits_fixed(AC3EncodeContext *s)
  654. {
  655.     static const int frame_bits_inc[8] = { 0, 0, 2, 2, 2, 4, 2, 4 };
  656.     int blk;
  657.     int frame_bits;
  658.  
  659.     /* assumptions:
  660.      *   no dynamic range codes
  661.      *   bit allocation parameters do not change between blocks
  662.      *   no delta bit allocation
  663.      *   no skipped data
  664.      *   no auxiliary data
  665.      *   no E-AC-3 metadata
  666.      */
  667.  
  668.     /* header */
  669.     frame_bits = 16; /* sync info */
  670.     if (s->eac3) {
  671.         /* bitstream info header */
  672.         frame_bits += 35;
  673.         frame_bits += 1 + 1;
  674.         if (s->num_blocks != 0x6)
  675.             frame_bits++;
  676.         frame_bits++;
  677.         /* audio frame header */
  678.         if (s->num_blocks == 6)
  679.             frame_bits += 2;
  680.         frame_bits += 10;
  681.         /* exponent strategy */
  682.         if (s->use_frame_exp_strategy)
  683.             frame_bits += 5 * s->fbw_channels;
  684.         else
  685.             frame_bits += s->num_blocks * 2 * s->fbw_channels;
  686.         if (s->lfe_on)
  687.             frame_bits += s->num_blocks;
  688.         /* converter exponent strategy */
  689.         if (s->num_blks_code != 0x3)
  690.             frame_bits++;
  691.         else
  692.             frame_bits += s->fbw_channels * 5;
  693.         /* snr offsets */
  694.         frame_bits += 10;
  695.         /* block start info */
  696.         if (s->num_blocks != 1)
  697.             frame_bits++;
  698.     } else {
  699.         frame_bits += 49;
  700.         frame_bits += frame_bits_inc[s->channel_mode];
  701.     }
  702.  
  703.     /* audio blocks */
  704.     for (blk = 0; blk < s->num_blocks; blk++) {
  705.         if (!s->eac3) {
  706.             /* block switch flags */
  707.             frame_bits += s->fbw_channels;
  708.  
  709.             /* dither flags */
  710.             frame_bits += s->fbw_channels;
  711.         }
  712.  
  713.         /* dynamic range */
  714.         frame_bits++;
  715.  
  716.         /* spectral extension */
  717.         if (s->eac3)
  718.             frame_bits++;
  719.  
  720.         if (!s->eac3) {
  721.             /* exponent strategy */
  722.             frame_bits += 2 * s->fbw_channels;
  723.             if (s->lfe_on)
  724.                 frame_bits++;
  725.  
  726.             /* bit allocation params */
  727.             frame_bits++;
  728.             if (!blk)
  729.                 frame_bits += 2 + 2 + 2 + 2 + 3;
  730.         }
  731.  
  732.         /* converter snr offset */
  733.         if (s->eac3)
  734.             frame_bits++;
  735.  
  736.         if (!s->eac3) {
  737.             /* delta bit allocation */
  738.             frame_bits++;
  739.  
  740.             /* skipped data */
  741.             frame_bits++;
  742.         }
  743.     }
  744.  
  745.     /* auxiliary data */
  746.     frame_bits++;
  747.  
  748.     /* CRC */
  749.     frame_bits += 1 + 16;
  750.  
  751.     s->frame_bits_fixed = frame_bits;
  752. }
  753.  
  754.  
  755. /*
  756.  * Initialize bit allocation.
  757.  * Set default parameter codes and calculate parameter values.
  758.  */
  759. static av_cold void bit_alloc_init(AC3EncodeContext *s)
  760. {
  761.     int ch;
  762.  
  763.     /* init default parameters */
  764.     s->slow_decay_code = 2;
  765.     s->fast_decay_code = 1;
  766.     s->slow_gain_code  = 1;
  767.     s->db_per_bit_code = s->eac3 ? 2 : 3;
  768.     s->floor_code      = 7;
  769.     for (ch = 0; ch <= s->channels; ch++)
  770.         s->fast_gain_code[ch] = 4;
  771.  
  772.     /* initial snr offset */
  773.     s->coarse_snr_offset = 40;
  774.  
  775.     /* compute real values */
  776.     /* currently none of these values change during encoding, so we can just
  777.        set them once at initialization */
  778.     s->bit_alloc.slow_decay = ff_ac3_slow_decay_tab[s->slow_decay_code] >> s->bit_alloc.sr_shift;
  779.     s->bit_alloc.fast_decay = ff_ac3_fast_decay_tab[s->fast_decay_code] >> s->bit_alloc.sr_shift;
  780.     s->bit_alloc.slow_gain  = ff_ac3_slow_gain_tab[s->slow_gain_code];
  781.     s->bit_alloc.db_per_bit = ff_ac3_db_per_bit_tab[s->db_per_bit_code];
  782.     s->bit_alloc.floor      = ff_ac3_floor_tab[s->floor_code];
  783.     s->bit_alloc.cpl_fast_leak = 0;
  784.     s->bit_alloc.cpl_slow_leak = 0;
  785.  
  786.     count_frame_bits_fixed(s);
  787. }
  788.  
  789.  
  790. /*
  791.  * Count the bits used to encode the frame, minus exponents and mantissas.
  792.  * Bits based on fixed parameters have already been counted, so now we just
  793.  * have to add the bits based on parameters that change during encoding.
  794.  */
  795. static void count_frame_bits(AC3EncodeContext *s)
  796. {
  797.     AC3EncOptions *opt = &s->options;
  798.     int blk, ch;
  799.     int frame_bits = 0;
  800.  
  801.     /* header */
  802.     if (s->eac3) {
  803.         if (opt->eac3_mixing_metadata) {
  804.             if (s->channel_mode > AC3_CHMODE_STEREO)
  805.                 frame_bits += 2;
  806.             if (s->has_center)
  807.                 frame_bits += 6;
  808.             if (s->has_surround)
  809.                 frame_bits += 6;
  810.             frame_bits += s->lfe_on;
  811.             frame_bits += 1 + 1 + 2;
  812.             if (s->channel_mode < AC3_CHMODE_STEREO)
  813.                 frame_bits++;
  814.             frame_bits++;
  815.         }
  816.         if (opt->eac3_info_metadata) {
  817.             frame_bits += 3 + 1 + 1;
  818.             if (s->channel_mode == AC3_CHMODE_STEREO)
  819.                 frame_bits += 2 + 2;
  820.             if (s->channel_mode >= AC3_CHMODE_2F2R)
  821.                 frame_bits += 2;
  822.             frame_bits++;
  823.             if (opt->audio_production_info)
  824.                 frame_bits += 5 + 2 + 1;
  825.             frame_bits++;
  826.         }
  827.         /* coupling */
  828.         if (s->channel_mode > AC3_CHMODE_MONO) {
  829.             frame_bits++;
  830.             for (blk = 1; blk < s->num_blocks; blk++) {
  831.                 AC3Block *block = &s->blocks[blk];
  832.                 frame_bits++;
  833.                 if (block->new_cpl_strategy)
  834.                     frame_bits++;
  835.             }
  836.         }
  837.         /* coupling exponent strategy */
  838.         if (s->cpl_on) {
  839.             if (s->use_frame_exp_strategy) {
  840.                 frame_bits += 5 * s->cpl_on;
  841.             } else {
  842.                 for (blk = 0; blk < s->num_blocks; blk++)
  843.                     frame_bits += 2 * s->blocks[blk].cpl_in_use;
  844.             }
  845.         }
  846.     } else {
  847.         if (opt->audio_production_info)
  848.             frame_bits += 7;
  849.         if (s->bitstream_id == 6) {
  850.             if (opt->extended_bsi_1)
  851.                 frame_bits += 14;
  852.             if (opt->extended_bsi_2)
  853.                 frame_bits += 14;
  854.         }
  855.     }
  856.  
  857.     /* audio blocks */
  858.     for (blk = 0; blk < s->num_blocks; blk++) {
  859.         AC3Block *block = &s->blocks[blk];
  860.  
  861.         /* coupling strategy */
  862.         if (!s->eac3)
  863.             frame_bits++;
  864.         if (block->new_cpl_strategy) {
  865.             if (!s->eac3)
  866.                 frame_bits++;
  867.             if (block->cpl_in_use) {
  868.                 if (s->eac3)
  869.                     frame_bits++;
  870.                 if (!s->eac3 || s->channel_mode != AC3_CHMODE_STEREO)
  871.                     frame_bits += s->fbw_channels;
  872.                 if (s->channel_mode == AC3_CHMODE_STEREO)
  873.                     frame_bits++;
  874.                 frame_bits += 4 + 4;
  875.                 if (s->eac3)
  876.                     frame_bits++;
  877.                 else
  878.                     frame_bits += s->num_cpl_subbands - 1;
  879.             }
  880.         }
  881.  
  882.         /* coupling coordinates */
  883.         if (block->cpl_in_use) {
  884.             for (ch = 1; ch <= s->fbw_channels; ch++) {
  885.                 if (block->channel_in_cpl[ch]) {
  886.                     if (!s->eac3 || block->new_cpl_coords[ch] != 2)
  887.                         frame_bits++;
  888.                     if (block->new_cpl_coords[ch]) {
  889.                         frame_bits += 2;
  890.                         frame_bits += (4 + 4) * s->num_cpl_bands;
  891.                     }
  892.                 }
  893.             }
  894.         }
  895.  
  896.         /* stereo rematrixing */
  897.         if (s->channel_mode == AC3_CHMODE_STEREO) {
  898.             if (!s->eac3 || blk > 0)
  899.                 frame_bits++;
  900.             if (s->blocks[blk].new_rematrixing_strategy)
  901.                 frame_bits += block->num_rematrixing_bands;
  902.         }
  903.  
  904.         /* bandwidth codes & gain range */
  905.         for (ch = 1; ch <= s->fbw_channels; ch++) {
  906.             if (s->exp_strategy[ch][blk] != EXP_REUSE) {
  907.                 if (!block->channel_in_cpl[ch])
  908.                     frame_bits += 6;
  909.                 frame_bits += 2;
  910.             }
  911.         }
  912.  
  913.         /* coupling exponent strategy */
  914.         if (!s->eac3 && block->cpl_in_use)
  915.             frame_bits += 2;
  916.  
  917.         /* snr offsets and fast gain codes */
  918.         if (!s->eac3) {
  919.             frame_bits++;
  920.             if (block->new_snr_offsets)
  921.                 frame_bits += 6 + (s->channels + block->cpl_in_use) * (4 + 3);
  922.         }
  923.  
  924.         /* coupling leak info */
  925.         if (block->cpl_in_use) {
  926.             if (!s->eac3 || block->new_cpl_leak != 2)
  927.                 frame_bits++;
  928.             if (block->new_cpl_leak)
  929.                 frame_bits += 3 + 3;
  930.         }
  931.     }
  932.  
  933.     s->frame_bits = s->frame_bits_fixed + frame_bits;
  934. }
  935.  
  936.  
  937. /*
  938.  * Calculate masking curve based on the final exponents.
  939.  * Also calculate the power spectral densities to use in future calculations.
  940.  */
  941. static void bit_alloc_masking(AC3EncodeContext *s)
  942. {
  943.     int blk, ch;
  944.  
  945.     for (blk = 0; blk < s->num_blocks; blk++) {
  946.         AC3Block *block = &s->blocks[blk];
  947.         for (ch = !block->cpl_in_use; ch <= s->channels; ch++) {
  948.             /* We only need psd and mask for calculating bap.
  949.                Since we currently do not calculate bap when exponent
  950.                strategy is EXP_REUSE we do not need to calculate psd or mask. */
  951.             if (s->exp_strategy[ch][blk] != EXP_REUSE) {
  952.                 ff_ac3_bit_alloc_calc_psd(block->exp[ch], s->start_freq[ch],
  953.                                           block->end_freq[ch], block->psd[ch],
  954.                                           block->band_psd[ch]);
  955.                 ff_ac3_bit_alloc_calc_mask(&s->bit_alloc, block->band_psd[ch],
  956.                                            s->start_freq[ch], block->end_freq[ch],
  957.                                            ff_ac3_fast_gain_tab[s->fast_gain_code[ch]],
  958.                                            ch == s->lfe_channel,
  959.                                            DBA_NONE, 0, NULL, NULL, NULL,
  960.                                            block->mask[ch]);
  961.             }
  962.         }
  963.     }
  964. }
  965.  
  966.  
  967. /*
  968.  * Ensure that bap for each block and channel point to the current bap_buffer.
  969.  * They may have been switched during the bit allocation search.
  970.  */
  971. static void reset_block_bap(AC3EncodeContext *s)
  972. {
  973.     int blk, ch;
  974.     uint8_t *ref_bap;
  975.  
  976.     if (s->ref_bap[0][0] == s->bap_buffer && s->ref_bap_set)
  977.         return;
  978.  
  979.     ref_bap = s->bap_buffer;
  980.     for (ch = 0; ch <= s->channels; ch++) {
  981.         for (blk = 0; blk < s->num_blocks; blk++)
  982.             s->ref_bap[ch][blk] = ref_bap + AC3_MAX_COEFS * s->exp_ref_block[ch][blk];
  983.         ref_bap += AC3_MAX_COEFS * s->num_blocks;
  984.     }
  985.     s->ref_bap_set = 1;
  986. }
  987.  
  988.  
  989. /**
  990.  * Initialize mantissa counts.
  991.  * These are set so that they are padded to the next whole group size when bits
  992.  * are counted in compute_mantissa_size.
  993.  *
  994.  * @param[in,out] mant_cnt  running counts for each bap value for each block
  995.  */
  996. static void count_mantissa_bits_init(uint16_t mant_cnt[AC3_MAX_BLOCKS][16])
  997. {
  998.     int blk;
  999.  
  1000.     for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
  1001.         memset(mant_cnt[blk], 0, sizeof(mant_cnt[blk]));
  1002.         mant_cnt[blk][1] = mant_cnt[blk][2] = 2;
  1003.         mant_cnt[blk][4] = 1;
  1004.     }
  1005. }
  1006.  
  1007.  
  1008. /**
  1009.  * Update mantissa bit counts for all blocks in 1 channel in a given bandwidth
  1010.  * range.
  1011.  *
  1012.  * @param s                 AC-3 encoder private context
  1013.  * @param ch                channel index
  1014.  * @param[in,out] mant_cnt  running counts for each bap value for each block
  1015.  * @param start             starting coefficient bin
  1016.  * @param end               ending coefficient bin
  1017.  */
  1018. static void count_mantissa_bits_update_ch(AC3EncodeContext *s, int ch,
  1019.                                           uint16_t mant_cnt[AC3_MAX_BLOCKS][16],
  1020.                                           int start, int end)
  1021. {
  1022.     int blk;
  1023.  
  1024.     for (blk = 0; blk < s->num_blocks; blk++) {
  1025.         AC3Block *block = &s->blocks[blk];
  1026.         if (ch == CPL_CH && !block->cpl_in_use)
  1027.             continue;
  1028.         s->ac3dsp.update_bap_counts(mant_cnt[blk],
  1029.                                     s->ref_bap[ch][blk] + start,
  1030.                                     FFMIN(end, block->end_freq[ch]) - start);
  1031.     }
  1032. }
  1033.  
  1034.  
  1035. /*
  1036.  * Count the number of mantissa bits in the frame based on the bap values.
  1037.  */
  1038. static int count_mantissa_bits(AC3EncodeContext *s)
  1039. {
  1040.     int ch, max_end_freq;
  1041.     LOCAL_ALIGNED_16(uint16_t, mant_cnt, [AC3_MAX_BLOCKS], [16]);
  1042.  
  1043.     count_mantissa_bits_init(mant_cnt);
  1044.  
  1045.     max_end_freq = s->bandwidth_code * 3 + 73;
  1046.     for (ch = !s->cpl_enabled; ch <= s->channels; ch++)
  1047.         count_mantissa_bits_update_ch(s, ch, mant_cnt, s->start_freq[ch],
  1048.                                       max_end_freq);
  1049.  
  1050.     return s->ac3dsp.compute_mantissa_size(mant_cnt);
  1051. }
  1052.  
  1053.  
  1054. /**
  1055.  * Run the bit allocation with a given SNR offset.
  1056.  * This calculates the bit allocation pointers that will be used to determine
  1057.  * the quantization of each mantissa.
  1058.  *
  1059.  * @param s           AC-3 encoder private context
  1060.  * @param snr_offset  SNR offset, 0 to 1023
  1061.  * @return the number of bits needed for mantissas if the given SNR offset is
  1062.  *         is used.
  1063.  */
  1064. static int bit_alloc(AC3EncodeContext *s, int snr_offset)
  1065. {
  1066.     int blk, ch;
  1067.  
  1068.     snr_offset = (snr_offset - 240) << 2;
  1069.  
  1070.     reset_block_bap(s);
  1071.     for (blk = 0; blk < s->num_blocks; blk++) {
  1072.         AC3Block *block = &s->blocks[blk];
  1073.  
  1074.         for (ch = !block->cpl_in_use; ch <= s->channels; ch++) {
  1075.             /* Currently the only bit allocation parameters which vary across
  1076.                blocks within a frame are the exponent values.  We can take
  1077.                advantage of that by reusing the bit allocation pointers
  1078.                whenever we reuse exponents. */
  1079.             if (s->exp_strategy[ch][blk] != EXP_REUSE) {
  1080.                 s->ac3dsp.bit_alloc_calc_bap(block->mask[ch], block->psd[ch],
  1081.                                              s->start_freq[ch], block->end_freq[ch],
  1082.                                              snr_offset, s->bit_alloc.floor,
  1083.                                              ff_ac3_bap_tab, s->ref_bap[ch][blk]);
  1084.             }
  1085.         }
  1086.     }
  1087.     return count_mantissa_bits(s);
  1088. }
  1089.  
  1090.  
  1091. /*
  1092.  * Constant bitrate bit allocation search.
  1093.  * Find the largest SNR offset that will allow data to fit in the frame.
  1094.  */
  1095. static int cbr_bit_allocation(AC3EncodeContext *s)
  1096. {
  1097.     int ch;
  1098.     int bits_left;
  1099.     int snr_offset, snr_incr;
  1100.  
  1101.     bits_left = 8 * s->frame_size - (s->frame_bits + s->exponent_bits);
  1102.     if (bits_left < 0)
  1103.         return AVERROR(EINVAL);
  1104.  
  1105.     snr_offset = s->coarse_snr_offset << 4;
  1106.  
  1107.     /* if previous frame SNR offset was 1023, check if current frame can also
  1108.        use SNR offset of 1023. if so, skip the search. */
  1109.     if ((snr_offset | s->fine_snr_offset[1]) == 1023) {
  1110.         if (bit_alloc(s, 1023) <= bits_left)
  1111.             return 0;
  1112.     }
  1113.  
  1114.     while (snr_offset >= 0 &&
  1115.            bit_alloc(s, snr_offset) > bits_left) {
  1116.         snr_offset -= 64;
  1117.     }
  1118.     if (snr_offset < 0)
  1119.         return AVERROR(EINVAL);
  1120.  
  1121.     FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
  1122.     for (snr_incr = 64; snr_incr > 0; snr_incr >>= 2) {
  1123.         while (snr_offset + snr_incr <= 1023 &&
  1124.                bit_alloc(s, snr_offset + snr_incr) <= bits_left) {
  1125.             snr_offset += snr_incr;
  1126.             FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
  1127.         }
  1128.     }
  1129.     FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
  1130.     reset_block_bap(s);
  1131.  
  1132.     s->coarse_snr_offset = snr_offset >> 4;
  1133.     for (ch = !s->cpl_on; ch <= s->channels; ch++)
  1134.         s->fine_snr_offset[ch] = snr_offset & 0xF;
  1135.  
  1136.     return 0;
  1137. }
  1138.  
  1139.  
  1140. /*
  1141.  * Perform bit allocation search.
  1142.  * Finds the SNR offset value that maximizes quality and fits in the specified
  1143.  * frame size.  Output is the SNR offset and a set of bit allocation pointers
  1144.  * used to quantize the mantissas.
  1145.  */
  1146. int ff_ac3_compute_bit_allocation(AC3EncodeContext *s)
  1147. {
  1148.     count_frame_bits(s);
  1149.  
  1150.     s->exponent_bits = count_exponent_bits(s);
  1151.  
  1152.     bit_alloc_masking(s);
  1153.  
  1154.     return cbr_bit_allocation(s);
  1155. }
  1156.  
  1157.  
  1158. /**
  1159.  * Symmetric quantization on 'levels' levels.
  1160.  *
  1161.  * @param c       unquantized coefficient
  1162.  * @param e       exponent
  1163.  * @param levels  number of quantization levels
  1164.  * @return        quantized coefficient
  1165.  */
  1166. static inline int sym_quant(int c, int e, int levels)
  1167. {
  1168.     int v = (((levels * c) >> (24 - e)) + levels) >> 1;
  1169.     av_assert2(v >= 0 && v < levels);
  1170.     return v;
  1171. }
  1172.  
  1173.  
  1174. /**
  1175.  * Asymmetric quantization on 2^qbits levels.
  1176.  *
  1177.  * @param c      unquantized coefficient
  1178.  * @param e      exponent
  1179.  * @param qbits  number of quantization bits
  1180.  * @return       quantized coefficient
  1181.  */
  1182. static inline int asym_quant(int c, int e, int qbits)
  1183. {
  1184.     int m;
  1185.  
  1186.     c = (((c << e) >> (24 - qbits)) + 1) >> 1;
  1187.     m = (1 << (qbits-1));
  1188.     if (c >= m)
  1189.         c = m - 1;
  1190.     av_assert2(c >= -m);
  1191.     return c;
  1192. }
  1193.  
  1194.  
  1195. /**
  1196.  * Quantize a set of mantissas for a single channel in a single block.
  1197.  *
  1198.  * @param s           Mantissa count context
  1199.  * @param fixed_coef  unquantized fixed-point coefficients
  1200.  * @param exp         exponents
  1201.  * @param bap         bit allocation pointer indices
  1202.  * @param[out] qmant  quantized coefficients
  1203.  * @param start_freq  starting coefficient bin
  1204.  * @param end_freq    ending coefficient bin
  1205.  */
  1206. static void quantize_mantissas_blk_ch(AC3Mant *s, int32_t *fixed_coef,
  1207.                                       uint8_t *exp, uint8_t *bap,
  1208.                                       int16_t *qmant, int start_freq,
  1209.                                       int end_freq)
  1210. {
  1211.     int i;
  1212.  
  1213.     for (i = start_freq; i < end_freq; i++) {
  1214.         int c = fixed_coef[i];
  1215.         int e = exp[i];
  1216.         int v = bap[i];
  1217.         if (v)
  1218.         switch (v) {
  1219.         case 1:
  1220.             v = sym_quant(c, e, 3);
  1221.             switch (s->mant1_cnt) {
  1222.             case 0:
  1223.                 s->qmant1_ptr = &qmant[i];
  1224.                 v = 9 * v;
  1225.                 s->mant1_cnt = 1;
  1226.                 break;
  1227.             case 1:
  1228.                 *s->qmant1_ptr += 3 * v;
  1229.                 s->mant1_cnt = 2;
  1230.                 v = 128;
  1231.                 break;
  1232.             default:
  1233.                 *s->qmant1_ptr += v;
  1234.                 s->mant1_cnt = 0;
  1235.                 v = 128;
  1236.                 break;
  1237.             }
  1238.             break;
  1239.         case 2:
  1240.             v = sym_quant(c, e, 5);
  1241.             switch (s->mant2_cnt) {
  1242.             case 0:
  1243.                 s->qmant2_ptr = &qmant[i];
  1244.                 v = 25 * v;
  1245.                 s->mant2_cnt = 1;
  1246.                 break;
  1247.             case 1:
  1248.                 *s->qmant2_ptr += 5 * v;
  1249.                 s->mant2_cnt = 2;
  1250.                 v = 128;
  1251.                 break;
  1252.             default:
  1253.                 *s->qmant2_ptr += v;
  1254.                 s->mant2_cnt = 0;
  1255.                 v = 128;
  1256.                 break;
  1257.             }
  1258.             break;
  1259.         case 3:
  1260.             v = sym_quant(c, e, 7);
  1261.             break;
  1262.         case 4:
  1263.             v = sym_quant(c, e, 11);
  1264.             switch (s->mant4_cnt) {
  1265.             case 0:
  1266.                 s->qmant4_ptr = &qmant[i];
  1267.                 v = 11 * v;
  1268.                 s->mant4_cnt = 1;
  1269.                 break;
  1270.             default:
  1271.                 *s->qmant4_ptr += v;
  1272.                 s->mant4_cnt = 0;
  1273.                 v = 128;
  1274.                 break;
  1275.             }
  1276.             break;
  1277.         case 5:
  1278.             v = sym_quant(c, e, 15);
  1279.             break;
  1280.         case 14:
  1281.             v = asym_quant(c, e, 14);
  1282.             break;
  1283.         case 15:
  1284.             v = asym_quant(c, e, 16);
  1285.             break;
  1286.         default:
  1287.             v = asym_quant(c, e, v - 1);
  1288.             break;
  1289.         }
  1290.         qmant[i] = v;
  1291.     }
  1292. }
  1293.  
  1294.  
  1295. /**
  1296.  * Quantize mantissas using coefficients, exponents, and bit allocation pointers.
  1297.  *
  1298.  * @param s  AC-3 encoder private context
  1299.  */
  1300. void ff_ac3_quantize_mantissas(AC3EncodeContext *s)
  1301. {
  1302.     int blk, ch, ch0=0, got_cpl;
  1303.  
  1304.     for (blk = 0; blk < s->num_blocks; blk++) {
  1305.         AC3Block *block = &s->blocks[blk];
  1306.         AC3Mant m = { 0 };
  1307.  
  1308.         got_cpl = !block->cpl_in_use;
  1309.         for (ch = 1; ch <= s->channels; ch++) {
  1310.             if (!got_cpl && ch > 1 && block->channel_in_cpl[ch-1]) {
  1311.                 ch0     = ch - 1;
  1312.                 ch      = CPL_CH;
  1313.                 got_cpl = 1;
  1314.             }
  1315.             quantize_mantissas_blk_ch(&m, block->fixed_coef[ch],
  1316.                                       s->blocks[s->exp_ref_block[ch][blk]].exp[ch],
  1317.                                       s->ref_bap[ch][blk], block->qmant[ch],
  1318.                                       s->start_freq[ch], block->end_freq[ch]);
  1319.             if (ch == CPL_CH)
  1320.                 ch = ch0;
  1321.         }
  1322.     }
  1323. }
  1324.  
  1325.  
  1326. /*
  1327.  * Write the AC-3 frame header to the output bitstream.
  1328.  */
  1329. static void ac3_output_frame_header(AC3EncodeContext *s)
  1330. {
  1331.     AC3EncOptions *opt = &s->options;
  1332.  
  1333.     put_bits(&s->pb, 16, 0x0b77);   /* frame header */
  1334.     put_bits(&s->pb, 16, 0);        /* crc1: will be filled later */
  1335.     put_bits(&s->pb, 2,  s->bit_alloc.sr_code);
  1336.     put_bits(&s->pb, 6,  s->frame_size_code + (s->frame_size - s->frame_size_min) / 2);
  1337.     put_bits(&s->pb, 5,  s->bitstream_id);
  1338.     put_bits(&s->pb, 3,  s->bitstream_mode);
  1339.     put_bits(&s->pb, 3,  s->channel_mode);
  1340.     if ((s->channel_mode & 0x01) && s->channel_mode != AC3_CHMODE_MONO)
  1341.         put_bits(&s->pb, 2, s->center_mix_level);
  1342.     if (s->channel_mode & 0x04)
  1343.         put_bits(&s->pb, 2, s->surround_mix_level);
  1344.     if (s->channel_mode == AC3_CHMODE_STEREO)
  1345.         put_bits(&s->pb, 2, opt->dolby_surround_mode);
  1346.     put_bits(&s->pb, 1, s->lfe_on); /* LFE */
  1347.     put_bits(&s->pb, 5, -opt->dialogue_level);
  1348.     put_bits(&s->pb, 1, 0);         /* no compression control word */
  1349.     put_bits(&s->pb, 1, 0);         /* no lang code */
  1350.     put_bits(&s->pb, 1, opt->audio_production_info);
  1351.     if (opt->audio_production_info) {
  1352.         put_bits(&s->pb, 5, opt->mixing_level - 80);
  1353.         put_bits(&s->pb, 2, opt->room_type);
  1354.     }
  1355.     put_bits(&s->pb, 1, opt->copyright);
  1356.     put_bits(&s->pb, 1, opt->original);
  1357.     if (s->bitstream_id == 6) {
  1358.         /* alternate bit stream syntax */
  1359.         put_bits(&s->pb, 1, opt->extended_bsi_1);
  1360.         if (opt->extended_bsi_1) {
  1361.             put_bits(&s->pb, 2, opt->preferred_stereo_downmix);
  1362.             put_bits(&s->pb, 3, s->ltrt_center_mix_level);
  1363.             put_bits(&s->pb, 3, s->ltrt_surround_mix_level);
  1364.             put_bits(&s->pb, 3, s->loro_center_mix_level);
  1365.             put_bits(&s->pb, 3, s->loro_surround_mix_level);
  1366.         }
  1367.         put_bits(&s->pb, 1, opt->extended_bsi_2);
  1368.         if (opt->extended_bsi_2) {
  1369.             put_bits(&s->pb, 2, opt->dolby_surround_ex_mode);
  1370.             put_bits(&s->pb, 2, opt->dolby_headphone_mode);
  1371.             put_bits(&s->pb, 1, opt->ad_converter_type);
  1372.             put_bits(&s->pb, 9, 0);     /* xbsi2 and encinfo : reserved */
  1373.         }
  1374.     } else {
  1375.     put_bits(&s->pb, 1, 0);         /* no time code 1 */
  1376.     put_bits(&s->pb, 1, 0);         /* no time code 2 */
  1377.     }
  1378.     put_bits(&s->pb, 1, 0);         /* no additional bit stream info */
  1379. }
  1380.  
  1381.  
  1382. /*
  1383.  * Write one audio block to the output bitstream.
  1384.  */
  1385. static void output_audio_block(AC3EncodeContext *s, int blk)
  1386. {
  1387.     int ch, i, baie, bnd, got_cpl, av_uninit(ch0);
  1388.     AC3Block *block = &s->blocks[blk];
  1389.  
  1390.     /* block switching */
  1391.     if (!s->eac3) {
  1392.         for (ch = 0; ch < s->fbw_channels; ch++)
  1393.             put_bits(&s->pb, 1, 0);
  1394.     }
  1395.  
  1396.     /* dither flags */
  1397.     if (!s->eac3) {
  1398.         for (ch = 0; ch < s->fbw_channels; ch++)
  1399.             put_bits(&s->pb, 1, 1);
  1400.     }
  1401.  
  1402.     /* dynamic range codes */
  1403.     put_bits(&s->pb, 1, 0);
  1404.  
  1405.     /* spectral extension */
  1406.     if (s->eac3)
  1407.         put_bits(&s->pb, 1, 0);
  1408.  
  1409.     /* channel coupling */
  1410.     if (!s->eac3)
  1411.         put_bits(&s->pb, 1, block->new_cpl_strategy);
  1412.     if (block->new_cpl_strategy) {
  1413.         if (!s->eac3)
  1414.             put_bits(&s->pb, 1, block->cpl_in_use);
  1415.         if (block->cpl_in_use) {
  1416.             int start_sub, end_sub;
  1417.             if (s->eac3)
  1418.                 put_bits(&s->pb, 1, 0); /* enhanced coupling */
  1419.             if (!s->eac3 || s->channel_mode != AC3_CHMODE_STEREO) {
  1420.                 for (ch = 1; ch <= s->fbw_channels; ch++)
  1421.                     put_bits(&s->pb, 1, block->channel_in_cpl[ch]);
  1422.             }
  1423.             if (s->channel_mode == AC3_CHMODE_STEREO)
  1424.                 put_bits(&s->pb, 1, 0); /* phase flags in use */
  1425.             start_sub = (s->start_freq[CPL_CH] - 37) / 12;
  1426.             end_sub   = (s->cpl_end_freq       - 37) / 12;
  1427.             put_bits(&s->pb, 4, start_sub);
  1428.             put_bits(&s->pb, 4, end_sub - 3);
  1429.             /* coupling band structure */
  1430.             if (s->eac3) {
  1431.                 put_bits(&s->pb, 1, 0); /* use default */
  1432.             } else {
  1433.                 for (bnd = start_sub+1; bnd < end_sub; bnd++)
  1434.                     put_bits(&s->pb, 1, ff_eac3_default_cpl_band_struct[bnd]);
  1435.             }
  1436.         }
  1437.     }
  1438.  
  1439.     /* coupling coordinates */
  1440.     if (block->cpl_in_use) {
  1441.         for (ch = 1; ch <= s->fbw_channels; ch++) {
  1442.             if (block->channel_in_cpl[ch]) {
  1443.                 if (!s->eac3 || block->new_cpl_coords[ch] != 2)
  1444.                     put_bits(&s->pb, 1, block->new_cpl_coords[ch]);
  1445.                 if (block->new_cpl_coords[ch]) {
  1446.                     put_bits(&s->pb, 2, block->cpl_master_exp[ch]);
  1447.                     for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
  1448.                         put_bits(&s->pb, 4, block->cpl_coord_exp [ch][bnd]);
  1449.                         put_bits(&s->pb, 4, block->cpl_coord_mant[ch][bnd]);
  1450.                     }
  1451.                 }
  1452.             }
  1453.         }
  1454.     }
  1455.  
  1456.     /* stereo rematrixing */
  1457.     if (s->channel_mode == AC3_CHMODE_STEREO) {
  1458.         if (!s->eac3 || blk > 0)
  1459.             put_bits(&s->pb, 1, block->new_rematrixing_strategy);
  1460.         if (block->new_rematrixing_strategy) {
  1461.             /* rematrixing flags */
  1462.             for (bnd = 0; bnd < block->num_rematrixing_bands; bnd++)
  1463.                 put_bits(&s->pb, 1, block->rematrixing_flags[bnd]);
  1464.         }
  1465.     }
  1466.  
  1467.     /* exponent strategy */
  1468.     if (!s->eac3) {
  1469.         for (ch = !block->cpl_in_use; ch <= s->fbw_channels; ch++)
  1470.             put_bits(&s->pb, 2, s->exp_strategy[ch][blk]);
  1471.         if (s->lfe_on)
  1472.             put_bits(&s->pb, 1, s->exp_strategy[s->lfe_channel][blk]);
  1473.     }
  1474.  
  1475.     /* bandwidth */
  1476.     for (ch = 1; ch <= s->fbw_channels; ch++) {
  1477.         if (s->exp_strategy[ch][blk] != EXP_REUSE && !block->channel_in_cpl[ch])
  1478.             put_bits(&s->pb, 6, s->bandwidth_code);
  1479.     }
  1480.  
  1481.     /* exponents */
  1482.     for (ch = !block->cpl_in_use; ch <= s->channels; ch++) {
  1483.         int nb_groups;
  1484.         int cpl = (ch == CPL_CH);
  1485.  
  1486.         if (s->exp_strategy[ch][blk] == EXP_REUSE)
  1487.             continue;
  1488.  
  1489.         /* DC exponent */
  1490.         put_bits(&s->pb, 4, block->grouped_exp[ch][0] >> cpl);
  1491.  
  1492.         /* exponent groups */
  1493.         nb_groups = exponent_group_tab[cpl][s->exp_strategy[ch][blk]-1][block->end_freq[ch]-s->start_freq[ch]];
  1494.         for (i = 1; i <= nb_groups; i++)
  1495.             put_bits(&s->pb, 7, block->grouped_exp[ch][i]);
  1496.  
  1497.         /* gain range info */
  1498.         if (ch != s->lfe_channel && !cpl)
  1499.             put_bits(&s->pb, 2, 0);
  1500.     }
  1501.  
  1502.     /* bit allocation info */
  1503.     if (!s->eac3) {
  1504.         baie = (blk == 0);
  1505.         put_bits(&s->pb, 1, baie);
  1506.         if (baie) {
  1507.             put_bits(&s->pb, 2, s->slow_decay_code);
  1508.             put_bits(&s->pb, 2, s->fast_decay_code);
  1509.             put_bits(&s->pb, 2, s->slow_gain_code);
  1510.             put_bits(&s->pb, 2, s->db_per_bit_code);
  1511.             put_bits(&s->pb, 3, s->floor_code);
  1512.         }
  1513.     }
  1514.  
  1515.     /* snr offset */
  1516.     if (!s->eac3) {
  1517.         put_bits(&s->pb, 1, block->new_snr_offsets);
  1518.         if (block->new_snr_offsets) {
  1519.             put_bits(&s->pb, 6, s->coarse_snr_offset);
  1520.             for (ch = !block->cpl_in_use; ch <= s->channels; ch++) {
  1521.                 put_bits(&s->pb, 4, s->fine_snr_offset[ch]);
  1522.                 put_bits(&s->pb, 3, s->fast_gain_code[ch]);
  1523.             }
  1524.         }
  1525.     } else {
  1526.         put_bits(&s->pb, 1, 0); /* no converter snr offset */
  1527.     }
  1528.  
  1529.     /* coupling leak */
  1530.     if (block->cpl_in_use) {
  1531.         if (!s->eac3 || block->new_cpl_leak != 2)
  1532.             put_bits(&s->pb, 1, block->new_cpl_leak);
  1533.         if (block->new_cpl_leak) {
  1534.             put_bits(&s->pb, 3, s->bit_alloc.cpl_fast_leak);
  1535.             put_bits(&s->pb, 3, s->bit_alloc.cpl_slow_leak);
  1536.         }
  1537.     }
  1538.  
  1539.     if (!s->eac3) {
  1540.         put_bits(&s->pb, 1, 0); /* no delta bit allocation */
  1541.         put_bits(&s->pb, 1, 0); /* no data to skip */
  1542.     }
  1543.  
  1544.     /* mantissas */
  1545.     got_cpl = !block->cpl_in_use;
  1546.     for (ch = 1; ch <= s->channels; ch++) {
  1547.         int b, q;
  1548.  
  1549.         if (!got_cpl && ch > 1 && block->channel_in_cpl[ch-1]) {
  1550.             ch0     = ch - 1;
  1551.             ch      = CPL_CH;
  1552.             got_cpl = 1;
  1553.         }
  1554.         for (i = s->start_freq[ch]; i < block->end_freq[ch]; i++) {
  1555.             q = block->qmant[ch][i];
  1556.             b = s->ref_bap[ch][blk][i];
  1557.             switch (b) {
  1558.             case 0:                                          break;
  1559.             case 1: if (q != 128) put_bits (&s->pb,   5, q); break;
  1560.             case 2: if (q != 128) put_bits (&s->pb,   7, q); break;
  1561.             case 3:               put_sbits(&s->pb,   3, q); break;
  1562.             case 4: if (q != 128) put_bits (&s->pb,   7, q); break;
  1563.             case 14:              put_sbits(&s->pb,  14, q); break;
  1564.             case 15:              put_sbits(&s->pb,  16, q); break;
  1565.             default:              put_sbits(&s->pb, b-1, q); break;
  1566.             }
  1567.         }
  1568.         if (ch == CPL_CH)
  1569.             ch = ch0;
  1570.     }
  1571. }
  1572.  
  1573.  
  1574. /** CRC-16 Polynomial */
  1575. #define CRC16_POLY ((1 << 0) | (1 << 2) | (1 << 15) | (1 << 16))
  1576.  
  1577.  
  1578. static unsigned int mul_poly(unsigned int a, unsigned int b, unsigned int poly)
  1579. {
  1580.     unsigned int c;
  1581.  
  1582.     c = 0;
  1583.     while (a) {
  1584.         if (a & 1)
  1585.             c ^= b;
  1586.         a = a >> 1;
  1587.         b = b << 1;
  1588.         if (b & (1 << 16))
  1589.             b ^= poly;
  1590.     }
  1591.     return c;
  1592. }
  1593.  
  1594.  
  1595. static unsigned int pow_poly(unsigned int a, unsigned int n, unsigned int poly)
  1596. {
  1597.     unsigned int r;
  1598.     r = 1;
  1599.     while (n) {
  1600.         if (n & 1)
  1601.             r = mul_poly(r, a, poly);
  1602.         a = mul_poly(a, a, poly);
  1603.         n >>= 1;
  1604.     }
  1605.     return r;
  1606. }
  1607.  
  1608.  
  1609. /*
  1610.  * Fill the end of the frame with 0's and compute the two CRCs.
  1611.  */
  1612. static void output_frame_end(AC3EncodeContext *s)
  1613. {
  1614.     const AVCRC *crc_ctx = av_crc_get_table(AV_CRC_16_ANSI);
  1615.     int frame_size_58, pad_bytes, crc1, crc2_partial, crc2, crc_inv;
  1616.     uint8_t *frame;
  1617.  
  1618.     frame_size_58 = ((s->frame_size >> 2) + (s->frame_size >> 4)) << 1;
  1619.  
  1620.     /* pad the remainder of the frame with zeros */
  1621.     av_assert2(s->frame_size * 8 - put_bits_count(&s->pb) >= 18);
  1622.     flush_put_bits(&s->pb);
  1623.     frame = s->pb.buf;
  1624.     pad_bytes = s->frame_size - (put_bits_ptr(&s->pb) - frame) - 2;
  1625.     av_assert2(pad_bytes >= 0);
  1626.     if (pad_bytes > 0)
  1627.         memset(put_bits_ptr(&s->pb), 0, pad_bytes);
  1628.  
  1629.     if (s->eac3) {
  1630.         /* compute crc2 */
  1631.         crc2_partial = av_crc(crc_ctx, 0, frame + 2, s->frame_size - 5);
  1632.     } else {
  1633.     /* compute crc1 */
  1634.     /* this is not so easy because it is at the beginning of the data... */
  1635.     crc1    = av_bswap16(av_crc(crc_ctx, 0, frame + 4, frame_size_58 - 4));
  1636.     crc_inv = s->crc_inv[s->frame_size > s->frame_size_min];
  1637.     crc1    = mul_poly(crc_inv, crc1, CRC16_POLY);
  1638.     AV_WB16(frame + 2, crc1);
  1639.  
  1640.     /* compute crc2 */
  1641.     crc2_partial = av_crc(crc_ctx, 0, frame + frame_size_58,
  1642.                           s->frame_size - frame_size_58 - 3);
  1643.     }
  1644.     crc2 = av_crc(crc_ctx, crc2_partial, frame + s->frame_size - 3, 1);
  1645.     /* ensure crc2 does not match sync word by flipping crcrsv bit if needed */
  1646.     if (crc2 == 0x770B) {
  1647.         frame[s->frame_size - 3] ^= 0x1;
  1648.         crc2 = av_crc(crc_ctx, crc2_partial, frame + s->frame_size - 3, 1);
  1649.     }
  1650.     crc2 = av_bswap16(crc2);
  1651.     AV_WB16(frame + s->frame_size - 2, crc2);
  1652. }
  1653.  
  1654.  
  1655. /**
  1656.  * Write the frame to the output bitstream.
  1657.  *
  1658.  * @param s      AC-3 encoder private context
  1659.  * @param frame  output data buffer
  1660.  */
  1661. void ff_ac3_output_frame(AC3EncodeContext *s, unsigned char *frame)
  1662. {
  1663.     int blk;
  1664.  
  1665.     init_put_bits(&s->pb, frame, AC3_MAX_CODED_FRAME_SIZE);
  1666.  
  1667.     s->output_frame_header(s);
  1668.  
  1669.     for (blk = 0; blk < s->num_blocks; blk++)
  1670.         output_audio_block(s, blk);
  1671.  
  1672.     output_frame_end(s);
  1673. }
  1674.  
  1675.  
  1676. static void dprint_options(AC3EncodeContext *s)
  1677. {
  1678. #ifdef DEBUG
  1679.     AVCodecContext *avctx = s->avctx;
  1680.     AC3EncOptions *opt = &s->options;
  1681.     char strbuf[32];
  1682.  
  1683.     switch (s->bitstream_id) {
  1684.     case  6:  av_strlcpy(strbuf, "AC-3 (alt syntax)",       32); break;
  1685.     case  8:  av_strlcpy(strbuf, "AC-3 (standard)",         32); break;
  1686.     case  9:  av_strlcpy(strbuf, "AC-3 (dnet half-rate)",   32); break;
  1687.     case 10:  av_strlcpy(strbuf, "AC-3 (dnet quater-rate)", 32); break;
  1688.     case 16:  av_strlcpy(strbuf, "E-AC-3 (enhanced)",       32); break;
  1689.     default: snprintf(strbuf, 32, "ERROR");
  1690.     }
  1691.     ff_dlog(avctx, "bitstream_id: %s (%d)\n", strbuf, s->bitstream_id);
  1692.     ff_dlog(avctx, "sample_fmt: %s\n", av_get_sample_fmt_name(avctx->sample_fmt));
  1693.     av_get_channel_layout_string(strbuf, 32, s->channels, avctx->channel_layout);
  1694.     ff_dlog(avctx, "channel_layout: %s\n", strbuf);
  1695.     ff_dlog(avctx, "sample_rate: %d\n", s->sample_rate);
  1696.     ff_dlog(avctx, "bit_rate: %d\n", s->bit_rate);
  1697.     ff_dlog(avctx, "blocks/frame: %d (code=%d)\n", s->num_blocks, s->num_blks_code);
  1698.     if (s->cutoff)
  1699.         ff_dlog(avctx, "cutoff: %d\n", s->cutoff);
  1700.  
  1701.     ff_dlog(avctx, "per_frame_metadata: %s\n",
  1702.             opt->allow_per_frame_metadata?"on":"off");
  1703.     if (s->has_center)
  1704.         ff_dlog(avctx, "center_mixlev: %0.3f (%d)\n", opt->center_mix_level,
  1705.                 s->center_mix_level);
  1706.     else
  1707.         ff_dlog(avctx, "center_mixlev: {not written}\n");
  1708.     if (s->has_surround)
  1709.         ff_dlog(avctx, "surround_mixlev: %0.3f (%d)\n", opt->surround_mix_level,
  1710.                 s->surround_mix_level);
  1711.     else
  1712.         ff_dlog(avctx, "surround_mixlev: {not written}\n");
  1713.     if (opt->audio_production_info) {
  1714.         ff_dlog(avctx, "mixing_level: %ddB\n", opt->mixing_level);
  1715.         switch (opt->room_type) {
  1716.         case AC3ENC_OPT_NOT_INDICATED: av_strlcpy(strbuf, "notindicated", 32); break;
  1717.         case AC3ENC_OPT_LARGE_ROOM:    av_strlcpy(strbuf, "large", 32);        break;
  1718.         case AC3ENC_OPT_SMALL_ROOM:    av_strlcpy(strbuf, "small", 32);        break;
  1719.         default: snprintf(strbuf, 32, "ERROR (%d)", opt->room_type);
  1720.         }
  1721.         ff_dlog(avctx, "room_type: %s\n", strbuf);
  1722.     } else {
  1723.         ff_dlog(avctx, "mixing_level: {not written}\n");
  1724.         ff_dlog(avctx, "room_type: {not written}\n");
  1725.     }
  1726.     ff_dlog(avctx, "copyright: %s\n", opt->copyright?"on":"off");
  1727.     ff_dlog(avctx, "dialnorm: %ddB\n", opt->dialogue_level);
  1728.     if (s->channel_mode == AC3_CHMODE_STEREO) {
  1729.         switch (opt->dolby_surround_mode) {
  1730.         case AC3ENC_OPT_NOT_INDICATED: av_strlcpy(strbuf, "notindicated", 32); break;
  1731.         case AC3ENC_OPT_MODE_ON:       av_strlcpy(strbuf, "on", 32);           break;
  1732.         case AC3ENC_OPT_MODE_OFF:      av_strlcpy(strbuf, "off", 32);          break;
  1733.         default: snprintf(strbuf, 32, "ERROR (%d)", opt->dolby_surround_mode);
  1734.         }
  1735.         ff_dlog(avctx, "dsur_mode: %s\n", strbuf);
  1736.     } else {
  1737.         ff_dlog(avctx, "dsur_mode: {not written}\n");
  1738.     }
  1739.     ff_dlog(avctx, "original: %s\n", opt->original?"on":"off");
  1740.  
  1741.     if (s->bitstream_id == 6) {
  1742.         if (opt->extended_bsi_1) {
  1743.             switch (opt->preferred_stereo_downmix) {
  1744.             case AC3ENC_OPT_NOT_INDICATED: av_strlcpy(strbuf, "notindicated", 32); break;
  1745.             case AC3ENC_OPT_DOWNMIX_LTRT:  av_strlcpy(strbuf, "ltrt", 32);         break;
  1746.             case AC3ENC_OPT_DOWNMIX_LORO:  av_strlcpy(strbuf, "loro", 32);         break;
  1747.             default: snprintf(strbuf, 32, "ERROR (%d)", opt->preferred_stereo_downmix);
  1748.             }
  1749.             ff_dlog(avctx, "dmix_mode: %s\n", strbuf);
  1750.             ff_dlog(avctx, "ltrt_cmixlev: %0.3f (%d)\n",
  1751.                     opt->ltrt_center_mix_level, s->ltrt_center_mix_level);
  1752.             ff_dlog(avctx, "ltrt_surmixlev: %0.3f (%d)\n",
  1753.                     opt->ltrt_surround_mix_level, s->ltrt_surround_mix_level);
  1754.             ff_dlog(avctx, "loro_cmixlev: %0.3f (%d)\n",
  1755.                     opt->loro_center_mix_level, s->loro_center_mix_level);
  1756.             ff_dlog(avctx, "loro_surmixlev: %0.3f (%d)\n",
  1757.                     opt->loro_surround_mix_level, s->loro_surround_mix_level);
  1758.         } else {
  1759.             ff_dlog(avctx, "extended bitstream info 1: {not written}\n");
  1760.         }
  1761.         if (opt->extended_bsi_2) {
  1762.             switch (opt->dolby_surround_ex_mode) {
  1763.             case AC3ENC_OPT_NOT_INDICATED: av_strlcpy(strbuf, "notindicated", 32); break;
  1764.             case AC3ENC_OPT_MODE_ON:       av_strlcpy(strbuf, "on", 32);           break;
  1765.             case AC3ENC_OPT_MODE_OFF:      av_strlcpy(strbuf, "off", 32);          break;
  1766.             default: snprintf(strbuf, 32, "ERROR (%d)", opt->dolby_surround_ex_mode);
  1767.             }
  1768.             ff_dlog(avctx, "dsurex_mode: %s\n", strbuf);
  1769.             switch (opt->dolby_headphone_mode) {
  1770.             case AC3ENC_OPT_NOT_INDICATED: av_strlcpy(strbuf, "notindicated", 32); break;
  1771.             case AC3ENC_OPT_MODE_ON:       av_strlcpy(strbuf, "on", 32);           break;
  1772.             case AC3ENC_OPT_MODE_OFF:      av_strlcpy(strbuf, "off", 32);          break;
  1773.             default: snprintf(strbuf, 32, "ERROR (%d)", opt->dolby_headphone_mode);
  1774.             }
  1775.             ff_dlog(avctx, "dheadphone_mode: %s\n", strbuf);
  1776.  
  1777.             switch (opt->ad_converter_type) {
  1778.             case AC3ENC_OPT_ADCONV_STANDARD: av_strlcpy(strbuf, "standard", 32); break;
  1779.             case AC3ENC_OPT_ADCONV_HDCD:     av_strlcpy(strbuf, "hdcd", 32);     break;
  1780.             default: snprintf(strbuf, 32, "ERROR (%d)", opt->ad_converter_type);
  1781.             }
  1782.             ff_dlog(avctx, "ad_conv_type: %s\n", strbuf);
  1783.         } else {
  1784.             ff_dlog(avctx, "extended bitstream info 2: {not written}\n");
  1785.         }
  1786.     }
  1787. #endif
  1788. }
  1789.  
  1790.  
  1791. #define FLT_OPTION_THRESHOLD 0.01
  1792.  
  1793. static int validate_float_option(float v, const float *v_list, int v_list_size)
  1794. {
  1795.     int i;
  1796.  
  1797.     for (i = 0; i < v_list_size; i++) {
  1798.         if (v < (v_list[i] + FLT_OPTION_THRESHOLD) &&
  1799.             v > (v_list[i] - FLT_OPTION_THRESHOLD))
  1800.             break;
  1801.     }
  1802.     if (i == v_list_size)
  1803.         return -1;
  1804.  
  1805.     return i;
  1806. }
  1807.  
  1808.  
  1809. static void validate_mix_level(void *log_ctx, const char *opt_name,
  1810.                                float *opt_param, const float *list,
  1811.                                int list_size, int default_value, int min_value,
  1812.                                int *ctx_param)
  1813. {
  1814.     int mixlev = validate_float_option(*opt_param, list, list_size);
  1815.     if (mixlev < min_value) {
  1816.         mixlev = default_value;
  1817.         if (*opt_param >= 0.0) {
  1818.             av_log(log_ctx, AV_LOG_WARNING, "requested %s is not valid. using "
  1819.                    "default value: %0.3f\n", opt_name, list[mixlev]);
  1820.         }
  1821.     }
  1822.     *opt_param = list[mixlev];
  1823.     *ctx_param = mixlev;
  1824. }
  1825.  
  1826.  
  1827. /**
  1828.  * Validate metadata options as set by AVOption system.
  1829.  * These values can optionally be changed per-frame.
  1830.  *
  1831.  * @param s  AC-3 encoder private context
  1832.  */
  1833. int ff_ac3_validate_metadata(AC3EncodeContext *s)
  1834. {
  1835.     AVCodecContext *avctx = s->avctx;
  1836.     AC3EncOptions *opt = &s->options;
  1837.  
  1838.     opt->audio_production_info = 0;
  1839.     opt->extended_bsi_1        = 0;
  1840.     opt->extended_bsi_2        = 0;
  1841.     opt->eac3_mixing_metadata  = 0;
  1842.     opt->eac3_info_metadata    = 0;
  1843.  
  1844.     /* determine mixing metadata / xbsi1 use */
  1845.     if (s->channel_mode > AC3_CHMODE_STEREO && opt->preferred_stereo_downmix != AC3ENC_OPT_NONE) {
  1846.         opt->extended_bsi_1       = 1;
  1847.         opt->eac3_mixing_metadata = 1;
  1848.     }
  1849.     if (s->has_center &&
  1850.         (opt->ltrt_center_mix_level >= 0 || opt->loro_center_mix_level >= 0)) {
  1851.         opt->extended_bsi_1       = 1;
  1852.         opt->eac3_mixing_metadata = 1;
  1853.     }
  1854.     if (s->has_surround &&
  1855.         (opt->ltrt_surround_mix_level >= 0 || opt->loro_surround_mix_level >= 0)) {
  1856.         opt->extended_bsi_1       = 1;
  1857.         opt->eac3_mixing_metadata = 1;
  1858.     }
  1859.  
  1860.     if (s->eac3) {
  1861.         /* determine info metadata use */
  1862.         if (avctx->audio_service_type != AV_AUDIO_SERVICE_TYPE_MAIN)
  1863.             opt->eac3_info_metadata = 1;
  1864.         if (opt->copyright != AC3ENC_OPT_NONE || opt->original != AC3ENC_OPT_NONE)
  1865.             opt->eac3_info_metadata = 1;
  1866.         if (s->channel_mode == AC3_CHMODE_STEREO &&
  1867.             (opt->dolby_headphone_mode != AC3ENC_OPT_NONE || opt->dolby_surround_mode != AC3ENC_OPT_NONE))
  1868.             opt->eac3_info_metadata = 1;
  1869.         if (s->channel_mode >= AC3_CHMODE_2F2R && opt->dolby_surround_ex_mode != AC3ENC_OPT_NONE)
  1870.             opt->eac3_info_metadata = 1;
  1871.         if (opt->mixing_level != AC3ENC_OPT_NONE || opt->room_type != AC3ENC_OPT_NONE ||
  1872.             opt->ad_converter_type != AC3ENC_OPT_NONE) {
  1873.             opt->audio_production_info = 1;
  1874.             opt->eac3_info_metadata    = 1;
  1875.         }
  1876.     } else {
  1877.         /* determine audio production info use */
  1878.         if (opt->mixing_level != AC3ENC_OPT_NONE || opt->room_type != AC3ENC_OPT_NONE)
  1879.             opt->audio_production_info = 1;
  1880.  
  1881.         /* determine xbsi2 use */
  1882.         if (s->channel_mode >= AC3_CHMODE_2F2R && opt->dolby_surround_ex_mode != AC3ENC_OPT_NONE)
  1883.             opt->extended_bsi_2 = 1;
  1884.         if (s->channel_mode == AC3_CHMODE_STEREO && opt->dolby_headphone_mode != AC3ENC_OPT_NONE)
  1885.             opt->extended_bsi_2 = 1;
  1886.         if (opt->ad_converter_type != AC3ENC_OPT_NONE)
  1887.             opt->extended_bsi_2 = 1;
  1888.     }
  1889.  
  1890.     /* validate AC-3 mixing levels */
  1891.     if (!s->eac3) {
  1892.         if (s->has_center) {
  1893.             validate_mix_level(avctx, "center_mix_level", &opt->center_mix_level,
  1894.                             cmixlev_options, CMIXLEV_NUM_OPTIONS, 1, 0,
  1895.                             &s->center_mix_level);
  1896.         }
  1897.         if (s->has_surround) {
  1898.             validate_mix_level(avctx, "surround_mix_level", &opt->surround_mix_level,
  1899.                             surmixlev_options, SURMIXLEV_NUM_OPTIONS, 1, 0,
  1900.                             &s->surround_mix_level);
  1901.         }
  1902.     }
  1903.  
  1904.     /* validate extended bsi 1 / mixing metadata */
  1905.     if (opt->extended_bsi_1 || opt->eac3_mixing_metadata) {
  1906.         /* default preferred stereo downmix */
  1907.         if (opt->preferred_stereo_downmix == AC3ENC_OPT_NONE)
  1908.             opt->preferred_stereo_downmix = AC3ENC_OPT_NOT_INDICATED;
  1909.         if (!s->eac3 || s->has_center) {
  1910.             /* validate Lt/Rt center mix level */
  1911.             validate_mix_level(avctx, "ltrt_center_mix_level",
  1912.                                &opt->ltrt_center_mix_level, extmixlev_options,
  1913.                                EXTMIXLEV_NUM_OPTIONS, 5, 0,
  1914.                                &s->ltrt_center_mix_level);
  1915.             /* validate Lo/Ro center mix level */
  1916.             validate_mix_level(avctx, "loro_center_mix_level",
  1917.                                &opt->loro_center_mix_level, extmixlev_options,
  1918.                                EXTMIXLEV_NUM_OPTIONS, 5, 0,
  1919.                                &s->loro_center_mix_level);
  1920.         }
  1921.         if (!s->eac3 || s->has_surround) {
  1922.             /* validate Lt/Rt surround mix level */
  1923.             validate_mix_level(avctx, "ltrt_surround_mix_level",
  1924.                                &opt->ltrt_surround_mix_level, extmixlev_options,
  1925.                                EXTMIXLEV_NUM_OPTIONS, 6, 3,
  1926.                                &s->ltrt_surround_mix_level);
  1927.             /* validate Lo/Ro surround mix level */
  1928.             validate_mix_level(avctx, "loro_surround_mix_level",
  1929.                                &opt->loro_surround_mix_level, extmixlev_options,
  1930.                                EXTMIXLEV_NUM_OPTIONS, 6, 3,
  1931.                                &s->loro_surround_mix_level);
  1932.         }
  1933.     }
  1934.  
  1935.     /* validate audio service type / channels combination */
  1936.     if ((avctx->audio_service_type == AV_AUDIO_SERVICE_TYPE_KARAOKE &&
  1937.          avctx->channels == 1) ||
  1938.         ((avctx->audio_service_type == AV_AUDIO_SERVICE_TYPE_COMMENTARY ||
  1939.           avctx->audio_service_type == AV_AUDIO_SERVICE_TYPE_EMERGENCY  ||
  1940.           avctx->audio_service_type == AV_AUDIO_SERVICE_TYPE_VOICE_OVER)
  1941.          && avctx->channels > 1)) {
  1942.         av_log(avctx, AV_LOG_ERROR, "invalid audio service type for the "
  1943.                                     "specified number of channels\n");
  1944.         return AVERROR(EINVAL);
  1945.     }
  1946.  
  1947.     /* validate extended bsi 2 / info metadata */
  1948.     if (opt->extended_bsi_2 || opt->eac3_info_metadata) {
  1949.         /* default dolby headphone mode */
  1950.         if (opt->dolby_headphone_mode == AC3ENC_OPT_NONE)
  1951.             opt->dolby_headphone_mode = AC3ENC_OPT_NOT_INDICATED;
  1952.         /* default dolby surround ex mode */
  1953.         if (opt->dolby_surround_ex_mode == AC3ENC_OPT_NONE)
  1954.             opt->dolby_surround_ex_mode = AC3ENC_OPT_NOT_INDICATED;
  1955.         /* default A/D converter type */
  1956.         if (opt->ad_converter_type == AC3ENC_OPT_NONE)
  1957.             opt->ad_converter_type = AC3ENC_OPT_ADCONV_STANDARD;
  1958.     }
  1959.  
  1960.     /* copyright & original defaults */
  1961.     if (!s->eac3 || opt->eac3_info_metadata) {
  1962.         /* default copyright */
  1963.         if (opt->copyright == AC3ENC_OPT_NONE)
  1964.             opt->copyright = AC3ENC_OPT_OFF;
  1965.         /* default original */
  1966.         if (opt->original == AC3ENC_OPT_NONE)
  1967.             opt->original = AC3ENC_OPT_ON;
  1968.     }
  1969.  
  1970.     /* dolby surround mode default */
  1971.     if (!s->eac3 || opt->eac3_info_metadata) {
  1972.         if (opt->dolby_surround_mode == AC3ENC_OPT_NONE)
  1973.             opt->dolby_surround_mode = AC3ENC_OPT_NOT_INDICATED;
  1974.     }
  1975.  
  1976.     /* validate audio production info */
  1977.     if (opt->audio_production_info) {
  1978.         if (opt->mixing_level == AC3ENC_OPT_NONE) {
  1979.             av_log(avctx, AV_LOG_ERROR, "mixing_level must be set if "
  1980.                    "room_type is set\n");
  1981.             return AVERROR(EINVAL);
  1982.         }
  1983.         if (opt->mixing_level < 80) {
  1984.             av_log(avctx, AV_LOG_ERROR, "invalid mixing level. must be between "
  1985.                    "80dB and 111dB\n");
  1986.             return AVERROR(EINVAL);
  1987.         }
  1988.         /* default room type */
  1989.         if (opt->room_type == AC3ENC_OPT_NONE)
  1990.             opt->room_type = AC3ENC_OPT_NOT_INDICATED;
  1991.     }
  1992.  
  1993.     /* set bitstream id for alternate bitstream syntax */
  1994.     if (!s->eac3 && (opt->extended_bsi_1 || opt->extended_bsi_2)) {
  1995.         if (s->bitstream_id > 8 && s->bitstream_id < 11) {
  1996.             static int warn_once = 1;
  1997.             if (warn_once) {
  1998.                 av_log(avctx, AV_LOG_WARNING, "alternate bitstream syntax is "
  1999.                        "not compatible with reduced samplerates. writing of "
  2000.                        "extended bitstream information will be disabled.\n");
  2001.                 warn_once = 0;
  2002.             }
  2003.         } else {
  2004.             s->bitstream_id = 6;
  2005.         }
  2006.     }
  2007.  
  2008.     return 0;
  2009. }
  2010.  
  2011.  
  2012. /**
  2013.  * Finalize encoding and free any memory allocated by the encoder.
  2014.  *
  2015.  * @param avctx  Codec context
  2016.  */
  2017. av_cold int ff_ac3_encode_close(AVCodecContext *avctx)
  2018. {
  2019.     int blk, ch;
  2020.     AC3EncodeContext *s = avctx->priv_data;
  2021.  
  2022.     av_freep(&s->windowed_samples);
  2023.     if (s->planar_samples)
  2024.     for (ch = 0; ch < s->channels; ch++)
  2025.         av_freep(&s->planar_samples[ch]);
  2026.     av_freep(&s->planar_samples);
  2027.     av_freep(&s->bap_buffer);
  2028.     av_freep(&s->bap1_buffer);
  2029.     av_freep(&s->mdct_coef_buffer);
  2030.     av_freep(&s->fixed_coef_buffer);
  2031.     av_freep(&s->exp_buffer);
  2032.     av_freep(&s->grouped_exp_buffer);
  2033.     av_freep(&s->psd_buffer);
  2034.     av_freep(&s->band_psd_buffer);
  2035.     av_freep(&s->mask_buffer);
  2036.     av_freep(&s->qmant_buffer);
  2037.     av_freep(&s->cpl_coord_exp_buffer);
  2038.     av_freep(&s->cpl_coord_mant_buffer);
  2039.     av_freep(&s->fdsp);
  2040.     for (blk = 0; blk < s->num_blocks; blk++) {
  2041.         AC3Block *block = &s->blocks[blk];
  2042.         av_freep(&block->mdct_coef);
  2043.         av_freep(&block->fixed_coef);
  2044.         av_freep(&block->exp);
  2045.         av_freep(&block->grouped_exp);
  2046.         av_freep(&block->psd);
  2047.         av_freep(&block->band_psd);
  2048.         av_freep(&block->mask);
  2049.         av_freep(&block->qmant);
  2050.         av_freep(&block->cpl_coord_exp);
  2051.         av_freep(&block->cpl_coord_mant);
  2052.     }
  2053.  
  2054.     s->mdct_end(s);
  2055.  
  2056.     return 0;
  2057. }
  2058.  
  2059.  
  2060. /*
  2061.  * Set channel information during initialization.
  2062.  */
  2063. static av_cold int set_channel_info(AC3EncodeContext *s, int channels,
  2064.                                     uint64_t *channel_layout)
  2065. {
  2066.     int ch_layout;
  2067.  
  2068.     if (channels < 1 || channels > AC3_MAX_CHANNELS)
  2069.         return AVERROR(EINVAL);
  2070.     if (*channel_layout > 0x7FF)
  2071.         return AVERROR(EINVAL);
  2072.     ch_layout = *channel_layout;
  2073.     if (!ch_layout)
  2074.         ch_layout = av_get_default_channel_layout(channels);
  2075.  
  2076.     s->lfe_on       = !!(ch_layout & AV_CH_LOW_FREQUENCY);
  2077.     s->channels     = channels;
  2078.     s->fbw_channels = channels - s->lfe_on;
  2079.     s->lfe_channel  = s->lfe_on ? s->fbw_channels + 1 : -1;
  2080.     if (s->lfe_on)
  2081.         ch_layout -= AV_CH_LOW_FREQUENCY;
  2082.  
  2083.     switch (ch_layout) {
  2084.     case AV_CH_LAYOUT_MONO:           s->channel_mode = AC3_CHMODE_MONO;   break;
  2085.     case AV_CH_LAYOUT_STEREO:         s->channel_mode = AC3_CHMODE_STEREO; break;
  2086.     case AV_CH_LAYOUT_SURROUND:       s->channel_mode = AC3_CHMODE_3F;     break;
  2087.     case AV_CH_LAYOUT_2_1:            s->channel_mode = AC3_CHMODE_2F1R;   break;
  2088.     case AV_CH_LAYOUT_4POINT0:        s->channel_mode = AC3_CHMODE_3F1R;   break;
  2089.     case AV_CH_LAYOUT_QUAD:
  2090.     case AV_CH_LAYOUT_2_2:            s->channel_mode = AC3_CHMODE_2F2R;   break;
  2091.     case AV_CH_LAYOUT_5POINT0:
  2092.     case AV_CH_LAYOUT_5POINT0_BACK:   s->channel_mode = AC3_CHMODE_3F2R;   break;
  2093.     default:
  2094.         return AVERROR(EINVAL);
  2095.     }
  2096.     s->has_center   = (s->channel_mode & 0x01) && s->channel_mode != AC3_CHMODE_MONO;
  2097.     s->has_surround =  s->channel_mode & 0x04;
  2098.  
  2099.     s->channel_map  = ff_ac3_enc_channel_map[s->channel_mode][s->lfe_on];
  2100.     *channel_layout = ch_layout;
  2101.     if (s->lfe_on)
  2102.         *channel_layout |= AV_CH_LOW_FREQUENCY;
  2103.  
  2104.     return 0;
  2105. }
  2106.  
  2107.  
  2108. static av_cold int validate_options(AC3EncodeContext *s)
  2109. {
  2110.     AVCodecContext *avctx = s->avctx;
  2111.     int i, ret, max_sr;
  2112.  
  2113.     /* validate channel layout */
  2114.     if (!avctx->channel_layout) {
  2115.         av_log(avctx, AV_LOG_WARNING, "No channel layout specified. The "
  2116.                                       "encoder will guess the layout, but it "
  2117.                                       "might be incorrect.\n");
  2118.     }
  2119.     ret = set_channel_info(s, avctx->channels, &avctx->channel_layout);
  2120.     if (ret) {
  2121.         av_log(avctx, AV_LOG_ERROR, "invalid channel layout\n");
  2122.         return ret;
  2123.     }
  2124.  
  2125.     /* validate sample rate */
  2126.     /* note: max_sr could be changed from 2 to 5 for E-AC-3 once we find a
  2127.              decoder that supports half sample rate so we can validate that
  2128.              the generated files are correct. */
  2129.     max_sr = s->eac3 ? 2 : 8;
  2130.     for (i = 0; i <= max_sr; i++) {
  2131.         if ((ff_ac3_sample_rate_tab[i % 3] >> (i / 3)) == avctx->sample_rate)
  2132.             break;
  2133.     }
  2134.     if (i > max_sr) {
  2135.         av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n");
  2136.         return AVERROR(EINVAL);
  2137.     }
  2138.     s->sample_rate        = avctx->sample_rate;
  2139.     s->bit_alloc.sr_shift = i / 3;
  2140.     s->bit_alloc.sr_code  = i % 3;
  2141.     s->bitstream_id       = s->eac3 ? 16 : 8 + s->bit_alloc.sr_shift;
  2142.  
  2143.     /* select a default bit rate if not set by the user */
  2144.     if (!avctx->bit_rate) {
  2145.         switch (s->fbw_channels) {
  2146.         case 1: avctx->bit_rate =  96000; break;
  2147.         case 2: avctx->bit_rate = 192000; break;
  2148.         case 3: avctx->bit_rate = 320000; break;
  2149.         case 4: avctx->bit_rate = 384000; break;
  2150.         case 5: avctx->bit_rate = 448000; break;
  2151.         }
  2152.     }
  2153.  
  2154.     /* validate bit rate */
  2155.     if (s->eac3) {
  2156.         int max_br, min_br, wpf, min_br_dist, min_br_code;
  2157.         int num_blks_code, num_blocks, frame_samples;
  2158.  
  2159.         /* calculate min/max bitrate */
  2160.         /* TODO: More testing with 3 and 2 blocks. All E-AC-3 samples I've
  2161.                  found use either 6 blocks or 1 block, even though 2 or 3 blocks
  2162.                  would work as far as the bit rate is concerned. */
  2163.         for (num_blks_code = 3; num_blks_code >= 0; num_blks_code--) {
  2164.             num_blocks = ((int[]){ 1, 2, 3, 6 })[num_blks_code];
  2165.             frame_samples  = AC3_BLOCK_SIZE * num_blocks;
  2166.             max_br = 2048 * s->sample_rate / frame_samples * 16;
  2167.             min_br = ((s->sample_rate + (frame_samples-1)) / frame_samples) * 16;
  2168.             if (avctx->bit_rate <= max_br)
  2169.                 break;
  2170.         }
  2171.         if (avctx->bit_rate < min_br || avctx->bit_rate > max_br) {
  2172.             av_log(avctx, AV_LOG_ERROR, "invalid bit rate. must be %d to %d "
  2173.                    "for this sample rate\n", min_br, max_br);
  2174.             return AVERROR(EINVAL);
  2175.         }
  2176.         s->num_blks_code = num_blks_code;
  2177.         s->num_blocks    = num_blocks;
  2178.  
  2179.         /* calculate words-per-frame for the selected bitrate */
  2180.         wpf = (avctx->bit_rate / 16) * frame_samples / s->sample_rate;
  2181.         av_assert1(wpf > 0 && wpf <= 2048);
  2182.  
  2183.         /* find the closest AC-3 bitrate code to the selected bitrate.
  2184.            this is needed for lookup tables for bandwidth and coupling
  2185.            parameter selection */
  2186.         min_br_code = -1;
  2187.         min_br_dist = INT_MAX;
  2188.         for (i = 0; i < 19; i++) {
  2189.             int br_dist = abs(ff_ac3_bitrate_tab[i] * 1000 - avctx->bit_rate);
  2190.             if (br_dist < min_br_dist) {
  2191.                 min_br_dist = br_dist;
  2192.                 min_br_code = i;
  2193.             }
  2194.         }
  2195.  
  2196.         /* make sure the minimum frame size is below the average frame size */
  2197.         s->frame_size_code = min_br_code << 1;
  2198.         while (wpf > 1 && wpf * s->sample_rate / AC3_FRAME_SIZE * 16 > avctx->bit_rate)
  2199.             wpf--;
  2200.         s->frame_size_min = 2 * wpf;
  2201.     } else {
  2202.         int best_br = 0, best_code = 0, best_diff = INT_MAX;
  2203.         for (i = 0; i < 19; i++) {
  2204.             int br   = (ff_ac3_bitrate_tab[i] >> s->bit_alloc.sr_shift) * 1000;
  2205.             int diff = abs(br - avctx->bit_rate);
  2206.             if (diff < best_diff) {
  2207.                 best_br   = br;
  2208.                 best_code = i;
  2209.                 best_diff = diff;
  2210.             }
  2211.             if (!best_diff)
  2212.                 break;
  2213.         }
  2214.         avctx->bit_rate    = best_br;
  2215.         s->frame_size_code = best_code << 1;
  2216.         s->frame_size_min  = 2 * ff_ac3_frame_size_tab[s->frame_size_code][s->bit_alloc.sr_code];
  2217.         s->num_blks_code   = 0x3;
  2218.         s->num_blocks      = 6;
  2219.     }
  2220.     s->bit_rate   = avctx->bit_rate;
  2221.     s->frame_size = s->frame_size_min;
  2222.  
  2223.     /* validate cutoff */
  2224.     if (avctx->cutoff < 0) {
  2225.         av_log(avctx, AV_LOG_ERROR, "invalid cutoff frequency\n");
  2226.         return AVERROR(EINVAL);
  2227.     }
  2228.     s->cutoff = avctx->cutoff;
  2229.     if (s->cutoff > (s->sample_rate >> 1))
  2230.         s->cutoff = s->sample_rate >> 1;
  2231.  
  2232.     ret = ff_ac3_validate_metadata(s);
  2233.     if (ret)
  2234.         return ret;
  2235.  
  2236.     s->rematrixing_enabled = s->options.stereo_rematrixing &&
  2237.                              (s->channel_mode == AC3_CHMODE_STEREO);
  2238.  
  2239.     s->cpl_enabled = s->options.channel_coupling &&
  2240.                      s->channel_mode >= AC3_CHMODE_STEREO;
  2241.  
  2242.     return 0;
  2243. }
  2244.  
  2245.  
  2246. /*
  2247.  * Set bandwidth for all channels.
  2248.  * The user can optionally supply a cutoff frequency. Otherwise an appropriate
  2249.  * default value will be used.
  2250.  */
  2251. static av_cold void set_bandwidth(AC3EncodeContext *s)
  2252. {
  2253.     int blk, ch, av_uninit(cpl_start);
  2254.  
  2255.     if (s->cutoff) {
  2256.         /* calculate bandwidth based on user-specified cutoff frequency */
  2257.         int fbw_coeffs;
  2258.         fbw_coeffs     = s->cutoff * 2 * AC3_MAX_COEFS / s->sample_rate;
  2259.         s->bandwidth_code = av_clip((fbw_coeffs - 73) / 3, 0, 60);
  2260.     } else {
  2261.         /* use default bandwidth setting */
  2262.         s->bandwidth_code = ac3_bandwidth_tab[s->fbw_channels-1][s->bit_alloc.sr_code][s->frame_size_code/2];
  2263.     }
  2264.  
  2265.     /* set number of coefficients for each channel */
  2266.     for (ch = 1; ch <= s->fbw_channels; ch++) {
  2267.         s->start_freq[ch] = 0;
  2268.         for (blk = 0; blk < s->num_blocks; blk++)
  2269.             s->blocks[blk].end_freq[ch] = s->bandwidth_code * 3 + 73;
  2270.     }
  2271.     /* LFE channel always has 7 coefs */
  2272.     if (s->lfe_on) {
  2273.         s->start_freq[s->lfe_channel] = 0;
  2274.         for (blk = 0; blk < s->num_blocks; blk++)
  2275.             s->blocks[blk].end_freq[ch] = 7;
  2276.     }
  2277.  
  2278.     /* initialize coupling strategy */
  2279.     if (s->cpl_enabled) {
  2280.         if (s->options.cpl_start != AC3ENC_OPT_AUTO) {
  2281.             cpl_start = s->options.cpl_start;
  2282.         } else {
  2283.             cpl_start = ac3_coupling_start_tab[s->channel_mode-2][s->bit_alloc.sr_code][s->frame_size_code/2];
  2284.             if (cpl_start < 0) {
  2285.                 if (s->options.channel_coupling == AC3ENC_OPT_AUTO)
  2286.                     s->cpl_enabled = 0;
  2287.                 else
  2288.                     cpl_start = 15;
  2289.             }
  2290.         }
  2291.     }
  2292.     if (s->cpl_enabled) {
  2293.         int i, cpl_start_band, cpl_end_band;
  2294.         uint8_t *cpl_band_sizes = s->cpl_band_sizes;
  2295.  
  2296.         cpl_end_band   = s->bandwidth_code / 4 + 3;
  2297.         cpl_start_band = av_clip(cpl_start, 0, FFMIN(cpl_end_band-1, 15));
  2298.  
  2299.         s->num_cpl_subbands = cpl_end_band - cpl_start_band;
  2300.  
  2301.         s->num_cpl_bands = 1;
  2302.         *cpl_band_sizes  = 12;
  2303.         for (i = cpl_start_band + 1; i < cpl_end_band; i++) {
  2304.             if (ff_eac3_default_cpl_band_struct[i]) {
  2305.                 *cpl_band_sizes += 12;
  2306.             } else {
  2307.                 s->num_cpl_bands++;
  2308.                 cpl_band_sizes++;
  2309.                 *cpl_band_sizes = 12;
  2310.             }
  2311.         }
  2312.  
  2313.         s->start_freq[CPL_CH] = cpl_start_band * 12 + 37;
  2314.         s->cpl_end_freq       = cpl_end_band   * 12 + 37;
  2315.         for (blk = 0; blk < s->num_blocks; blk++)
  2316.             s->blocks[blk].end_freq[CPL_CH] = s->cpl_end_freq;
  2317.     }
  2318. }
  2319.  
  2320.  
  2321. static av_cold int allocate_buffers(AC3EncodeContext *s)
  2322. {
  2323.     AVCodecContext *avctx = s->avctx;
  2324.     int blk, ch;
  2325.     int channels = s->channels + 1; /* includes coupling channel */
  2326.     int channel_blocks = channels * s->num_blocks;
  2327.     int total_coefs    = AC3_MAX_COEFS * channel_blocks;
  2328.  
  2329.     if (s->allocate_sample_buffers(s))
  2330.         goto alloc_fail;
  2331.  
  2332.     FF_ALLOC_ARRAY_OR_GOTO(avctx, s->bap_buffer, total_coefs,
  2333.                      sizeof(*s->bap_buffer), alloc_fail);
  2334.     FF_ALLOC_ARRAY_OR_GOTO(avctx, s->bap1_buffer, total_coefs,
  2335.                      sizeof(*s->bap1_buffer), alloc_fail);
  2336.     FF_ALLOCZ_ARRAY_OR_GOTO(avctx, s->mdct_coef_buffer, total_coefs,
  2337.                       sizeof(*s->mdct_coef_buffer), alloc_fail);
  2338.     FF_ALLOC_ARRAY_OR_GOTO(avctx, s->exp_buffer, total_coefs,
  2339.                      sizeof(*s->exp_buffer), alloc_fail);
  2340.     FF_ALLOC_ARRAY_OR_GOTO(avctx, s->grouped_exp_buffer, channel_blocks, 128 *
  2341.                      sizeof(*s->grouped_exp_buffer), alloc_fail);
  2342.     FF_ALLOC_ARRAY_OR_GOTO(avctx, s->psd_buffer, total_coefs,
  2343.                      sizeof(*s->psd_buffer), alloc_fail);
  2344.     FF_ALLOC_ARRAY_OR_GOTO(avctx, s->band_psd_buffer, channel_blocks, 64 *
  2345.                      sizeof(*s->band_psd_buffer), alloc_fail);
  2346.     FF_ALLOC_ARRAY_OR_GOTO(avctx, s->mask_buffer, channel_blocks, 64 *
  2347.                      sizeof(*s->mask_buffer), alloc_fail);
  2348.     FF_ALLOC_ARRAY_OR_GOTO(avctx, s->qmant_buffer, total_coefs,
  2349.                      sizeof(*s->qmant_buffer), alloc_fail);
  2350.     if (s->cpl_enabled) {
  2351.         FF_ALLOC_ARRAY_OR_GOTO(avctx, s->cpl_coord_exp_buffer, channel_blocks, 16 *
  2352.                          sizeof(*s->cpl_coord_exp_buffer), alloc_fail);
  2353.         FF_ALLOC_ARRAY_OR_GOTO(avctx, s->cpl_coord_mant_buffer, channel_blocks, 16 *
  2354.                          sizeof(*s->cpl_coord_mant_buffer), alloc_fail);
  2355.     }
  2356.     for (blk = 0; blk < s->num_blocks; blk++) {
  2357.         AC3Block *block = &s->blocks[blk];
  2358.         FF_ALLOCZ_ARRAY_OR_GOTO(avctx, block->mdct_coef, channels, sizeof(*block->mdct_coef),
  2359.                           alloc_fail);
  2360.         FF_ALLOCZ_ARRAY_OR_GOTO(avctx, block->exp, channels, sizeof(*block->exp),
  2361.                           alloc_fail);
  2362.         FF_ALLOCZ_ARRAY_OR_GOTO(avctx, block->grouped_exp, channels, sizeof(*block->grouped_exp),
  2363.                           alloc_fail);
  2364.         FF_ALLOCZ_ARRAY_OR_GOTO(avctx, block->psd, channels, sizeof(*block->psd),
  2365.                           alloc_fail);
  2366.         FF_ALLOCZ_ARRAY_OR_GOTO(avctx, block->band_psd, channels, sizeof(*block->band_psd),
  2367.                           alloc_fail);
  2368.         FF_ALLOCZ_ARRAY_OR_GOTO(avctx, block->mask, channels, sizeof(*block->mask),
  2369.                           alloc_fail);
  2370.         FF_ALLOCZ_ARRAY_OR_GOTO(avctx, block->qmant, channels, sizeof(*block->qmant),
  2371.                           alloc_fail);
  2372.         if (s->cpl_enabled) {
  2373.             FF_ALLOCZ_ARRAY_OR_GOTO(avctx, block->cpl_coord_exp, channels, sizeof(*block->cpl_coord_exp),
  2374.                               alloc_fail);
  2375.             FF_ALLOCZ_ARRAY_OR_GOTO(avctx, block->cpl_coord_mant, channels, sizeof(*block->cpl_coord_mant),
  2376.                               alloc_fail);
  2377.         }
  2378.  
  2379.         for (ch = 0; ch < channels; ch++) {
  2380.             /* arrangement: block, channel, coeff */
  2381.             block->grouped_exp[ch] = &s->grouped_exp_buffer[128           * (blk * channels + ch)];
  2382.             block->psd[ch]         = &s->psd_buffer        [AC3_MAX_COEFS * (blk * channels + ch)];
  2383.             block->band_psd[ch]    = &s->band_psd_buffer   [64            * (blk * channels + ch)];
  2384.             block->mask[ch]        = &s->mask_buffer       [64            * (blk * channels + ch)];
  2385.             block->qmant[ch]       = &s->qmant_buffer      [AC3_MAX_COEFS * (blk * channels + ch)];
  2386.             if (s->cpl_enabled) {
  2387.                 block->cpl_coord_exp[ch]  = &s->cpl_coord_exp_buffer [16  * (blk * channels + ch)];
  2388.                 block->cpl_coord_mant[ch] = &s->cpl_coord_mant_buffer[16  * (blk * channels + ch)];
  2389.             }
  2390.  
  2391.             /* arrangement: channel, block, coeff */
  2392.             block->exp[ch]         = &s->exp_buffer        [AC3_MAX_COEFS * (s->num_blocks * ch + blk)];
  2393.             block->mdct_coef[ch]   = &s->mdct_coef_buffer  [AC3_MAX_COEFS * (s->num_blocks * ch + blk)];
  2394.         }
  2395.     }
  2396.  
  2397.     if (!s->fixed_point) {
  2398.         FF_ALLOCZ_ARRAY_OR_GOTO(avctx, s->fixed_coef_buffer, total_coefs,
  2399.                           sizeof(*s->fixed_coef_buffer), alloc_fail);
  2400.         for (blk = 0; blk < s->num_blocks; blk++) {
  2401.             AC3Block *block = &s->blocks[blk];
  2402.             FF_ALLOCZ_ARRAY_OR_GOTO(avctx, block->fixed_coef, channels,
  2403.                               sizeof(*block->fixed_coef), alloc_fail);
  2404.             for (ch = 0; ch < channels; ch++)
  2405.                 block->fixed_coef[ch] = &s->fixed_coef_buffer[AC3_MAX_COEFS * (s->num_blocks * ch + blk)];
  2406.         }
  2407.     } else {
  2408.         for (blk = 0; blk < s->num_blocks; blk++) {
  2409.             AC3Block *block = &s->blocks[blk];
  2410.             FF_ALLOCZ_ARRAY_OR_GOTO(avctx, block->fixed_coef, channels,
  2411.                               sizeof(*block->fixed_coef), alloc_fail);
  2412.             for (ch = 0; ch < channels; ch++)
  2413.                 block->fixed_coef[ch] = (int32_t *)block->mdct_coef[ch];
  2414.         }
  2415.     }
  2416.  
  2417.     return 0;
  2418. alloc_fail:
  2419.     return AVERROR(ENOMEM);
  2420. }
  2421.  
  2422.  
  2423. av_cold int ff_ac3_encode_init(AVCodecContext *avctx)
  2424. {
  2425.     AC3EncodeContext *s = avctx->priv_data;
  2426.     int ret, frame_size_58;
  2427.  
  2428.     s->avctx = avctx;
  2429.  
  2430.     s->eac3 = avctx->codec_id == AV_CODEC_ID_EAC3;
  2431.  
  2432.     ff_ac3_common_init();
  2433.  
  2434.     ret = validate_options(s);
  2435.     if (ret)
  2436.         return ret;
  2437.  
  2438.     avctx->frame_size = AC3_BLOCK_SIZE * s->num_blocks;
  2439.     avctx->initial_padding = AC3_BLOCK_SIZE;
  2440.  
  2441.     s->bitstream_mode = avctx->audio_service_type;
  2442.     if (s->bitstream_mode == AV_AUDIO_SERVICE_TYPE_KARAOKE)
  2443.         s->bitstream_mode = 0x7;
  2444.  
  2445.     s->bits_written    = 0;
  2446.     s->samples_written = 0;
  2447.  
  2448.     /* calculate crc_inv for both possible frame sizes */
  2449.     frame_size_58 = (( s->frame_size    >> 2) + ( s->frame_size    >> 4)) << 1;
  2450.     s->crc_inv[0] = pow_poly((CRC16_POLY >> 1), (8 * frame_size_58) - 16, CRC16_POLY);
  2451.     if (s->bit_alloc.sr_code == 1) {
  2452.         frame_size_58 = (((s->frame_size+2) >> 2) + ((s->frame_size+2) >> 4)) << 1;
  2453.         s->crc_inv[1] = pow_poly((CRC16_POLY >> 1), (8 * frame_size_58) - 16, CRC16_POLY);
  2454.     }
  2455.  
  2456.     /* set function pointers */
  2457.     if (CONFIG_AC3_FIXED_ENCODER && s->fixed_point) {
  2458.         s->mdct_end                     = ff_ac3_fixed_mdct_end;
  2459.         s->mdct_init                    = ff_ac3_fixed_mdct_init;
  2460.         s->allocate_sample_buffers      = ff_ac3_fixed_allocate_sample_buffers;
  2461.     } else if (CONFIG_AC3_ENCODER || CONFIG_EAC3_ENCODER) {
  2462.         s->mdct_end                     = ff_ac3_float_mdct_end;
  2463.         s->mdct_init                    = ff_ac3_float_mdct_init;
  2464.         s->allocate_sample_buffers      = ff_ac3_float_allocate_sample_buffers;
  2465.     }
  2466.     if (CONFIG_EAC3_ENCODER && s->eac3)
  2467.         s->output_frame_header = ff_eac3_output_frame_header;
  2468.     else
  2469.         s->output_frame_header = ac3_output_frame_header;
  2470.  
  2471.     set_bandwidth(s);
  2472.  
  2473.     exponent_init(s);
  2474.  
  2475.     bit_alloc_init(s);
  2476.  
  2477.     ret = s->mdct_init(s);
  2478.     if (ret)
  2479.         goto init_fail;
  2480.  
  2481.     ret = allocate_buffers(s);
  2482.     if (ret)
  2483.         goto init_fail;
  2484.  
  2485.     ff_audiodsp_init(&s->adsp);
  2486.     ff_me_cmp_init(&s->mecc, avctx);
  2487.     ff_ac3dsp_init(&s->ac3dsp, avctx->flags & AV_CODEC_FLAG_BITEXACT);
  2488.  
  2489.     dprint_options(s);
  2490.  
  2491.     return 0;
  2492. init_fail:
  2493.     ff_ac3_encode_close(avctx);
  2494.     return ret;
  2495. }
  2496.