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  1. /*
  2.  * AAC encoder psychoacoustic model
  3.  * Copyright (C) 2008 Konstantin Shishkov
  4.  *
  5.  * This file is part of FFmpeg.
  6.  *
  7.  * FFmpeg is free software; you can redistribute it and/or
  8.  * modify it under the terms of the GNU Lesser General Public
  9.  * License as published by the Free Software Foundation; either
  10.  * version 2.1 of the License, or (at your option) any later version.
  11.  *
  12.  * FFmpeg is distributed in the hope that it will be useful,
  13.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15.  * Lesser General Public License for more details.
  16.  *
  17.  * You should have received a copy of the GNU Lesser General Public
  18.  * License along with FFmpeg; if not, write to the Free Software
  19.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20.  */
  21.  
  22. /**
  23.  * @file
  24.  * AAC encoder psychoacoustic model
  25.  */
  26.  
  27. #include "libavutil/attributes.h"
  28. #include "libavutil/libm.h"
  29.  
  30. #include "avcodec.h"
  31. #include "aactab.h"
  32. #include "psymodel.h"
  33.  
  34. /***********************************
  35.  *              TODOs:
  36.  * try other bitrate controlling mechanism (maybe use ratecontrol.c?)
  37.  * control quality for quality-based output
  38.  **********************************/
  39.  
  40. /**
  41.  * constants for 3GPP AAC psychoacoustic model
  42.  * @{
  43.  */
  44. #define PSY_3GPP_THR_SPREAD_HI   1.5f // spreading factor for low-to-hi threshold spreading  (15 dB/Bark)
  45. #define PSY_3GPP_THR_SPREAD_LOW  3.0f // spreading factor for hi-to-low threshold spreading  (30 dB/Bark)
  46. /* spreading factor for low-to-hi energy spreading, long block, > 22kbps/channel (20dB/Bark) */
  47. #define PSY_3GPP_EN_SPREAD_HI_L1 2.0f
  48. /* spreading factor for low-to-hi energy spreading, long block, <= 22kbps/channel (15dB/Bark) */
  49. #define PSY_3GPP_EN_SPREAD_HI_L2 1.5f
  50. /* spreading factor for low-to-hi energy spreading, short block (15 dB/Bark) */
  51. #define PSY_3GPP_EN_SPREAD_HI_S  1.5f
  52. /* spreading factor for hi-to-low energy spreading, long block (30dB/Bark) */
  53. #define PSY_3GPP_EN_SPREAD_LOW_L 3.0f
  54. /* spreading factor for hi-to-low energy spreading, short block (20dB/Bark) */
  55. #define PSY_3GPP_EN_SPREAD_LOW_S 2.0f
  56.  
  57. #define PSY_3GPP_RPEMIN      0.01f
  58. #define PSY_3GPP_RPELEV      2.0f
  59.  
  60. #define PSY_3GPP_C1          3.0f           /* log2(8) */
  61. #define PSY_3GPP_C2          1.3219281f     /* log2(2.5) */
  62. #define PSY_3GPP_C3          0.55935729f    /* 1 - C2 / C1 */
  63.  
  64. #define PSY_SNR_1DB          7.9432821e-1f  /* -1dB */
  65. #define PSY_SNR_25DB         3.1622776e-3f  /* -25dB */
  66.  
  67. #define PSY_3GPP_SAVE_SLOPE_L  -0.46666667f
  68. #define PSY_3GPP_SAVE_SLOPE_S  -0.36363637f
  69. #define PSY_3GPP_SAVE_ADD_L    -0.84285712f
  70. #define PSY_3GPP_SAVE_ADD_S    -0.75f
  71. #define PSY_3GPP_SPEND_SLOPE_L  0.66666669f
  72. #define PSY_3GPP_SPEND_SLOPE_S  0.81818181f
  73. #define PSY_3GPP_SPEND_ADD_L   -0.35f
  74. #define PSY_3GPP_SPEND_ADD_S   -0.26111111f
  75. #define PSY_3GPP_CLIP_LO_L      0.2f
  76. #define PSY_3GPP_CLIP_LO_S      0.2f
  77. #define PSY_3GPP_CLIP_HI_L      0.95f
  78. #define PSY_3GPP_CLIP_HI_S      0.75f
  79.  
  80. #define PSY_3GPP_AH_THR_LONG    0.5f
  81. #define PSY_3GPP_AH_THR_SHORT   0.63f
  82.  
  83. enum {
  84.     PSY_3GPP_AH_NONE,
  85.     PSY_3GPP_AH_INACTIVE,
  86.     PSY_3GPP_AH_ACTIVE
  87. };
  88.  
  89. #define PSY_3GPP_BITS_TO_PE(bits) ((bits) * 1.18f)
  90.  
  91. /* LAME psy model constants */
  92. #define PSY_LAME_FIR_LEN 21         ///< LAME psy model FIR order
  93. #define AAC_BLOCK_SIZE_LONG 1024    ///< long block size
  94. #define AAC_BLOCK_SIZE_SHORT 128    ///< short block size
  95. #define AAC_NUM_BLOCKS_SHORT 8      ///< number of blocks in a short sequence
  96. #define PSY_LAME_NUM_SUBBLOCKS 3    ///< Number of sub-blocks in each short block
  97.  
  98. /**
  99.  * @}
  100.  */
  101.  
  102. /**
  103.  * information for single band used by 3GPP TS26.403-inspired psychoacoustic model
  104.  */
  105. typedef struct AacPsyBand{
  106.     float energy;       ///< band energy
  107.     float thr;          ///< energy threshold
  108.     float thr_quiet;    ///< threshold in quiet
  109.     float nz_lines;     ///< number of non-zero spectral lines
  110.     float active_lines; ///< number of active spectral lines
  111.     float pe;           ///< perceptual entropy
  112.     float pe_const;     ///< constant part of the PE calculation
  113.     float norm_fac;     ///< normalization factor for linearization
  114.     int   avoid_holes;  ///< hole avoidance flag
  115. }AacPsyBand;
  116.  
  117. /**
  118.  * single/pair channel context for psychoacoustic model
  119.  */
  120. typedef struct AacPsyChannel{
  121.     AacPsyBand band[128];               ///< bands information
  122.     AacPsyBand prev_band[128];          ///< bands information from the previous frame
  123.  
  124.     float       win_energy;              ///< sliding average of channel energy
  125.     float       iir_state[2];            ///< hi-pass IIR filter state
  126.     uint8_t     next_grouping;           ///< stored grouping scheme for the next frame (in case of 8 short window sequence)
  127.     enum WindowSequence next_window_seq; ///< window sequence to be used in the next frame
  128.     /* LAME psy model specific members */
  129.     float attack_threshold;              ///< attack threshold for this channel
  130.     float prev_energy_subshort[AAC_NUM_BLOCKS_SHORT * PSY_LAME_NUM_SUBBLOCKS];
  131.     int   prev_attack;                   ///< attack value for the last short block in the previous sequence
  132. }AacPsyChannel;
  133.  
  134. /**
  135.  * psychoacoustic model frame type-dependent coefficients
  136.  */
  137. typedef struct AacPsyCoeffs{
  138.     float ath;           ///< absolute threshold of hearing per bands
  139.     float barks;         ///< Bark value for each spectral band in long frame
  140.     float spread_low[2]; ///< spreading factor for low-to-high threshold spreading in long frame
  141.     float spread_hi [2]; ///< spreading factor for high-to-low threshold spreading in long frame
  142.     float min_snr;       ///< minimal SNR
  143. }AacPsyCoeffs;
  144.  
  145. /**
  146.  * 3GPP TS26.403-inspired psychoacoustic model specific data
  147.  */
  148. typedef struct AacPsyContext{
  149.     int chan_bitrate;     ///< bitrate per channel
  150.     int frame_bits;       ///< average bits per frame
  151.     int fill_level;       ///< bit reservoir fill level
  152.     struct {
  153.         float min;        ///< minimum allowed PE for bit factor calculation
  154.         float max;        ///< maximum allowed PE for bit factor calculation
  155.         float previous;   ///< allowed PE of the previous frame
  156.         float correction; ///< PE correction factor
  157.     } pe;
  158.     AacPsyCoeffs psy_coef[2][64];
  159.     AacPsyChannel *ch;
  160. }AacPsyContext;
  161.  
  162. /**
  163.  * LAME psy model preset struct
  164.  */
  165. typedef struct PsyLamePreset {
  166.     int   quality;  ///< Quality to map the rest of the vaules to.
  167.      /* This is overloaded to be both kbps per channel in ABR mode, and
  168.       * requested quality in constant quality mode.
  169.       */
  170.     float st_lrm;   ///< short threshold for L, R, and M channels
  171. } PsyLamePreset;
  172.  
  173. /**
  174.  * LAME psy model preset table for ABR
  175.  */
  176. static const PsyLamePreset psy_abr_map[] = {
  177. /* TODO: Tuning. These were taken from LAME. */
  178. /* kbps/ch st_lrm   */
  179.     {  8,  6.60},
  180.     { 16,  6.60},
  181.     { 24,  6.60},
  182.     { 32,  6.60},
  183.     { 40,  6.60},
  184.     { 48,  6.60},
  185.     { 56,  6.60},
  186.     { 64,  6.40},
  187.     { 80,  6.00},
  188.     { 96,  5.60},
  189.     {112,  5.20},
  190.     {128,  5.20},
  191.     {160,  5.20}
  192. };
  193.  
  194. /**
  195. * LAME psy model preset table for constant quality
  196. */
  197. static const PsyLamePreset psy_vbr_map[] = {
  198. /* vbr_q  st_lrm    */
  199.     { 0,  4.20},
  200.     { 1,  4.20},
  201.     { 2,  4.20},
  202.     { 3,  4.20},
  203.     { 4,  4.20},
  204.     { 5,  4.20},
  205.     { 6,  4.20},
  206.     { 7,  4.20},
  207.     { 8,  4.20},
  208.     { 9,  4.20},
  209.     {10,  4.20}
  210. };
  211.  
  212. /**
  213.  * LAME psy model FIR coefficient table
  214.  */
  215. static const float psy_fir_coeffs[] = {
  216.     -8.65163e-18 * 2, -0.00851586 * 2, -6.74764e-18 * 2, 0.0209036 * 2,
  217.     -3.36639e-17 * 2, -0.0438162 * 2,  -1.54175e-17 * 2, 0.0931738 * 2,
  218.     -5.52212e-17 * 2, -0.313819 * 2
  219. };
  220.  
  221. #if ARCH_MIPS
  222. #   include "mips/aacpsy_mips.h"
  223. #endif /* ARCH_MIPS */
  224.  
  225. /**
  226.  * Calculate the ABR attack threshold from the above LAME psymodel table.
  227.  */
  228. static float lame_calc_attack_threshold(int bitrate)
  229. {
  230.     /* Assume max bitrate to start with */
  231.     int lower_range = 12, upper_range = 12;
  232.     int lower_range_kbps = psy_abr_map[12].quality;
  233.     int upper_range_kbps = psy_abr_map[12].quality;
  234.     int i;
  235.  
  236.     /* Determine which bitrates the value specified falls between.
  237.      * If the loop ends without breaking our above assumption of 320kbps was correct.
  238.      */
  239.     for (i = 1; i < 13; i++) {
  240.         if (FFMAX(bitrate, psy_abr_map[i].quality) != bitrate) {
  241.             upper_range = i;
  242.             upper_range_kbps = psy_abr_map[i    ].quality;
  243.             lower_range = i - 1;
  244.             lower_range_kbps = psy_abr_map[i - 1].quality;
  245.             break; /* Upper range found */
  246.         }
  247.     }
  248.  
  249.     /* Determine which range the value specified is closer to */
  250.     if ((upper_range_kbps - bitrate) > (bitrate - lower_range_kbps))
  251.         return psy_abr_map[lower_range].st_lrm;
  252.     return psy_abr_map[upper_range].st_lrm;
  253. }
  254.  
  255. /**
  256.  * LAME psy model specific initialization
  257.  */
  258. static av_cold void lame_window_init(AacPsyContext *ctx, AVCodecContext *avctx)
  259. {
  260.     int i, j;
  261.  
  262.     for (i = 0; i < avctx->channels; i++) {
  263.         AacPsyChannel *pch = &ctx->ch[i];
  264.  
  265.         if (avctx->flags & AV_CODEC_FLAG_QSCALE)
  266.             pch->attack_threshold = psy_vbr_map[avctx->global_quality / FF_QP2LAMBDA].st_lrm;
  267.         else
  268.             pch->attack_threshold = lame_calc_attack_threshold(avctx->bit_rate / avctx->channels / 1000);
  269.  
  270.         for (j = 0; j < AAC_NUM_BLOCKS_SHORT * PSY_LAME_NUM_SUBBLOCKS; j++)
  271.             pch->prev_energy_subshort[j] = 10.0f;
  272.     }
  273. }
  274.  
  275. /**
  276.  * Calculate Bark value for given line.
  277.  */
  278. static av_cold float calc_bark(float f)
  279. {
  280.     return 13.3f * atanf(0.00076f * f) + 3.5f * atanf((f / 7500.0f) * (f / 7500.0f));
  281. }
  282.  
  283. #define ATH_ADD 4
  284. /**
  285.  * Calculate ATH value for given frequency.
  286.  * Borrowed from Lame.
  287.  */
  288. static av_cold float ath(float f, float add)
  289. {
  290.     f /= 1000.0f;
  291.     return    3.64 * pow(f, -0.8)
  292.             - 6.8  * exp(-0.6  * (f - 3.4) * (f - 3.4))
  293.             + 6.0  * exp(-0.15 * (f - 8.7) * (f - 8.7))
  294.             + (0.6 + 0.04 * add) * 0.001 * f * f * f * f;
  295. }
  296.  
  297. static av_cold int psy_3gpp_init(FFPsyContext *ctx) {
  298.     AacPsyContext *pctx;
  299.     float bark;
  300.     int i, j, g, start;
  301.     float prev, minscale, minath, minsnr, pe_min;
  302.     const int chan_bitrate = ctx->avctx->bit_rate / ctx->avctx->channels;
  303.     const int bandwidth    = ctx->avctx->cutoff ? ctx->avctx->cutoff : AAC_CUTOFF(ctx->avctx);
  304.     const float num_bark   = calc_bark((float)bandwidth);
  305.  
  306.     ctx->model_priv_data = av_mallocz(sizeof(AacPsyContext));
  307.     if (!ctx->model_priv_data)
  308.         return AVERROR(ENOMEM);
  309.     pctx = (AacPsyContext*) ctx->model_priv_data;
  310.  
  311.     pctx->chan_bitrate = chan_bitrate;
  312.     pctx->frame_bits   = chan_bitrate * AAC_BLOCK_SIZE_LONG / ctx->avctx->sample_rate;
  313.     pctx->pe.min       =  8.0f * AAC_BLOCK_SIZE_LONG * bandwidth / (ctx->avctx->sample_rate * 2.0f);
  314.     pctx->pe.max       = 12.0f * AAC_BLOCK_SIZE_LONG * bandwidth / (ctx->avctx->sample_rate * 2.0f);
  315.     ctx->bitres.size   = 6144 - pctx->frame_bits;
  316.     ctx->bitres.size  -= ctx->bitres.size % 8;
  317.     pctx->fill_level   = ctx->bitres.size;
  318.     minath = ath(3410 - 0.733 * ATH_ADD, ATH_ADD);
  319.     for (j = 0; j < 2; j++) {
  320.         AacPsyCoeffs *coeffs = pctx->psy_coef[j];
  321.         const uint8_t *band_sizes = ctx->bands[j];
  322.         float line_to_frequency = ctx->avctx->sample_rate / (j ? 256.f : 2048.0f);
  323.         float avg_chan_bits = chan_bitrate * (j ? 128.0f : 1024.0f) / ctx->avctx->sample_rate;
  324.         /* reference encoder uses 2.4% here instead of 60% like the spec says */
  325.         float bark_pe = 0.024f * PSY_3GPP_BITS_TO_PE(avg_chan_bits) / num_bark;
  326.         float en_spread_low = j ? PSY_3GPP_EN_SPREAD_LOW_S : PSY_3GPP_EN_SPREAD_LOW_L;
  327.         /* High energy spreading for long blocks <= 22kbps/channel and short blocks are the same. */
  328.         float en_spread_hi  = (j || (chan_bitrate <= 22.0f)) ? PSY_3GPP_EN_SPREAD_HI_S : PSY_3GPP_EN_SPREAD_HI_L1;
  329.  
  330.         i = 0;
  331.         prev = 0.0;
  332.         for (g = 0; g < ctx->num_bands[j]; g++) {
  333.             i += band_sizes[g];
  334.             bark = calc_bark((i-1) * line_to_frequency);
  335.             coeffs[g].barks = (bark + prev) / 2.0;
  336.             prev = bark;
  337.         }
  338.         for (g = 0; g < ctx->num_bands[j] - 1; g++) {
  339.             AacPsyCoeffs *coeff = &coeffs[g];
  340.             float bark_width = coeffs[g+1].barks - coeffs->barks;
  341.             coeff->spread_low[0] = pow(10.0, -bark_width * PSY_3GPP_THR_SPREAD_LOW);
  342.             coeff->spread_hi [0] = pow(10.0, -bark_width * PSY_3GPP_THR_SPREAD_HI);
  343.             coeff->spread_low[1] = pow(10.0, -bark_width * en_spread_low);
  344.             coeff->spread_hi [1] = pow(10.0, -bark_width * en_spread_hi);
  345.             pe_min = bark_pe * bark_width;
  346.             minsnr = exp2(pe_min / band_sizes[g]) - 1.5f;
  347.             coeff->min_snr = av_clipf(1.0f / minsnr, PSY_SNR_25DB, PSY_SNR_1DB);
  348.         }
  349.         start = 0;
  350.         for (g = 0; g < ctx->num_bands[j]; g++) {
  351.             minscale = ath(start * line_to_frequency, ATH_ADD);
  352.             for (i = 1; i < band_sizes[g]; i++)
  353.                 minscale = FFMIN(minscale, ath((start + i) * line_to_frequency, ATH_ADD));
  354.             coeffs[g].ath = minscale - minath;
  355.             start += band_sizes[g];
  356.         }
  357.     }
  358.  
  359.     pctx->ch = av_mallocz_array(ctx->avctx->channels, sizeof(AacPsyChannel));
  360.     if (!pctx->ch) {
  361.         av_freep(&ctx->model_priv_data);
  362.         return AVERROR(ENOMEM);
  363.     }
  364.  
  365.     lame_window_init(pctx, ctx->avctx);
  366.  
  367.     return 0;
  368. }
  369.  
  370. /**
  371.  * IIR filter used in block switching decision
  372.  */
  373. static float iir_filter(int in, float state[2])
  374. {
  375.     float ret;
  376.  
  377.     ret = 0.7548f * (in - state[0]) + 0.5095f * state[1];
  378.     state[0] = in;
  379.     state[1] = ret;
  380.     return ret;
  381. }
  382.  
  383. /**
  384.  * window grouping information stored as bits (0 - new group, 1 - group continues)
  385.  */
  386. static const uint8_t window_grouping[9] = {
  387.     0xB6, 0x6C, 0xD8, 0xB2, 0x66, 0xC6, 0x96, 0x36, 0x36
  388. };
  389.  
  390. /**
  391.  * Tell encoder which window types to use.
  392.  * @see 3GPP TS26.403 5.4.1 "Blockswitching"
  393.  */
  394. static av_unused FFPsyWindowInfo psy_3gpp_window(FFPsyContext *ctx,
  395.                                                  const int16_t *audio,
  396.                                                  const int16_t *la,
  397.                                                  int channel, int prev_type)
  398. {
  399.     int i, j;
  400.     int br               = ctx->avctx->bit_rate / ctx->avctx->channels;
  401.     int attack_ratio     = br <= 16000 ? 18 : 10;
  402.     AacPsyContext *pctx = (AacPsyContext*) ctx->model_priv_data;
  403.     AacPsyChannel *pch  = &pctx->ch[channel];
  404.     uint8_t grouping     = 0;
  405.     int next_type        = pch->next_window_seq;
  406.     FFPsyWindowInfo wi  = { { 0 } };
  407.  
  408.     if (la) {
  409.         float s[8], v;
  410.         int switch_to_eight = 0;
  411.         float sum = 0.0, sum2 = 0.0;
  412.         int attack_n = 0;
  413.         int stay_short = 0;
  414.         for (i = 0; i < 8; i++) {
  415.             for (j = 0; j < 128; j++) {
  416.                 v = iir_filter(la[i*128+j], pch->iir_state);
  417.                 sum += v*v;
  418.             }
  419.             s[i]  = sum;
  420.             sum2 += sum;
  421.         }
  422.         for (i = 0; i < 8; i++) {
  423.             if (s[i] > pch->win_energy * attack_ratio) {
  424.                 attack_n        = i + 1;
  425.                 switch_to_eight = 1;
  426.                 break;
  427.             }
  428.         }
  429.         pch->win_energy = pch->win_energy*7/8 + sum2/64;
  430.  
  431.         wi.window_type[1] = prev_type;
  432.         switch (prev_type) {
  433.         case ONLY_LONG_SEQUENCE:
  434.             wi.window_type[0] = switch_to_eight ? LONG_START_SEQUENCE : ONLY_LONG_SEQUENCE;
  435.             next_type = switch_to_eight ? EIGHT_SHORT_SEQUENCE : ONLY_LONG_SEQUENCE;
  436.             break;
  437.         case LONG_START_SEQUENCE:
  438.             wi.window_type[0] = EIGHT_SHORT_SEQUENCE;
  439.             grouping = pch->next_grouping;
  440.             next_type = switch_to_eight ? EIGHT_SHORT_SEQUENCE : LONG_STOP_SEQUENCE;
  441.             break;
  442.         case LONG_STOP_SEQUENCE:
  443.             wi.window_type[0] = switch_to_eight ? LONG_START_SEQUENCE : ONLY_LONG_SEQUENCE;
  444.             next_type = switch_to_eight ? EIGHT_SHORT_SEQUENCE : ONLY_LONG_SEQUENCE;
  445.             break;
  446.         case EIGHT_SHORT_SEQUENCE:
  447.             stay_short = next_type == EIGHT_SHORT_SEQUENCE || switch_to_eight;
  448.             wi.window_type[0] = stay_short ? EIGHT_SHORT_SEQUENCE : LONG_STOP_SEQUENCE;
  449.             grouping = next_type == EIGHT_SHORT_SEQUENCE ? pch->next_grouping : 0;
  450.             next_type = switch_to_eight ? EIGHT_SHORT_SEQUENCE : LONG_STOP_SEQUENCE;
  451.             break;
  452.         }
  453.  
  454.         pch->next_grouping = window_grouping[attack_n];
  455.         pch->next_window_seq = next_type;
  456.     } else {
  457.         for (i = 0; i < 3; i++)
  458.             wi.window_type[i] = prev_type;
  459.         grouping = (prev_type == EIGHT_SHORT_SEQUENCE) ? window_grouping[0] : 0;
  460.     }
  461.  
  462.     wi.window_shape   = 1;
  463.     if (wi.window_type[0] != EIGHT_SHORT_SEQUENCE) {
  464.         wi.num_windows = 1;
  465.         wi.grouping[0] = 1;
  466.     } else {
  467.         int lastgrp = 0;
  468.         wi.num_windows = 8;
  469.         for (i = 0; i < 8; i++) {
  470.             if (!((grouping >> i) & 1))
  471.                 lastgrp = i;
  472.             wi.grouping[lastgrp]++;
  473.         }
  474.     }
  475.  
  476.     return wi;
  477. }
  478.  
  479. /* 5.6.1.2 "Calculation of Bit Demand" */
  480. static int calc_bit_demand(AacPsyContext *ctx, float pe, int bits, int size,
  481.                            int short_window)
  482. {
  483.     const float bitsave_slope  = short_window ? PSY_3GPP_SAVE_SLOPE_S  : PSY_3GPP_SAVE_SLOPE_L;
  484.     const float bitsave_add    = short_window ? PSY_3GPP_SAVE_ADD_S    : PSY_3GPP_SAVE_ADD_L;
  485.     const float bitspend_slope = short_window ? PSY_3GPP_SPEND_SLOPE_S : PSY_3GPP_SPEND_SLOPE_L;
  486.     const float bitspend_add   = short_window ? PSY_3GPP_SPEND_ADD_S   : PSY_3GPP_SPEND_ADD_L;
  487.     const float clip_low       = short_window ? PSY_3GPP_CLIP_LO_S     : PSY_3GPP_CLIP_LO_L;
  488.     const float clip_high      = short_window ? PSY_3GPP_CLIP_HI_S     : PSY_3GPP_CLIP_HI_L;
  489.     float clipped_pe, bit_save, bit_spend, bit_factor, fill_level;
  490.  
  491.     ctx->fill_level += ctx->frame_bits - bits;
  492.     ctx->fill_level  = av_clip(ctx->fill_level, 0, size);
  493.     fill_level = av_clipf((float)ctx->fill_level / size, clip_low, clip_high);
  494.     clipped_pe = av_clipf(pe, ctx->pe.min, ctx->pe.max);
  495.     bit_save   = (fill_level + bitsave_add) * bitsave_slope;
  496.     assert(bit_save <= 0.3f && bit_save >= -0.05000001f);
  497.     bit_spend  = (fill_level + bitspend_add) * bitspend_slope;
  498.     assert(bit_spend <= 0.5f && bit_spend >= -0.1f);
  499.     /* The bit factor graph in the spec is obviously incorrect.
  500.      *      bit_spend + ((bit_spend - bit_spend))...
  501.      * The reference encoder subtracts everything from 1, but also seems incorrect.
  502.      *      1 - bit_save + ((bit_spend + bit_save))...
  503.      * Hopefully below is correct.
  504.      */
  505.     bit_factor = 1.0f - bit_save + ((bit_spend - bit_save) / (ctx->pe.max - ctx->pe.min)) * (clipped_pe - ctx->pe.min);
  506.     /* NOTE: The reference encoder attempts to center pe max/min around the current pe. */
  507.     ctx->pe.max = FFMAX(pe, ctx->pe.max);
  508.     ctx->pe.min = FFMIN(pe, ctx->pe.min);
  509.  
  510.     return FFMIN(ctx->frame_bits * bit_factor, ctx->frame_bits + size - bits);
  511. }
  512.  
  513. static float calc_pe_3gpp(AacPsyBand *band)
  514. {
  515.     float pe, a;
  516.  
  517.     band->pe           = 0.0f;
  518.     band->pe_const     = 0.0f;
  519.     band->active_lines = 0.0f;
  520.     if (band->energy > band->thr) {
  521.         a  = log2f(band->energy);
  522.         pe = a - log2f(band->thr);
  523.         band->active_lines = band->nz_lines;
  524.         if (pe < PSY_3GPP_C1) {
  525.             pe = pe * PSY_3GPP_C3 + PSY_3GPP_C2;
  526.             a  = a  * PSY_3GPP_C3 + PSY_3GPP_C2;
  527.             band->active_lines *= PSY_3GPP_C3;
  528.         }
  529.         band->pe       = pe * band->nz_lines;
  530.         band->pe_const = a  * band->nz_lines;
  531.     }
  532.  
  533.     return band->pe;
  534. }
  535.  
  536. static float calc_reduction_3gpp(float a, float desired_pe, float pe,
  537.                                  float active_lines)
  538. {
  539.     float thr_avg, reduction;
  540.  
  541.     if(active_lines == 0.0)
  542.         return 0;
  543.  
  544.     thr_avg   = exp2f((a - pe) / (4.0f * active_lines));
  545.     reduction = exp2f((a - desired_pe) / (4.0f * active_lines)) - thr_avg;
  546.  
  547.     return FFMAX(reduction, 0.0f);
  548. }
  549.  
  550. static float calc_reduced_thr_3gpp(AacPsyBand *band, float min_snr,
  551.                                    float reduction)
  552. {
  553.     float thr = band->thr;
  554.  
  555.     if (band->energy > thr) {
  556.         thr = sqrtf(thr);
  557.         thr = sqrtf(thr) + reduction;
  558.         thr *= thr;
  559.         thr *= thr;
  560.  
  561.         /* This deviates from the 3GPP spec to match the reference encoder.
  562.          * It performs min(thr_reduced, max(thr, energy/min_snr)) only for bands
  563.          * that have hole avoidance on (active or inactive). It always reduces the
  564.          * threshold of bands with hole avoidance off.
  565.          */
  566.         if (thr > band->energy * min_snr && band->avoid_holes != PSY_3GPP_AH_NONE) {
  567.             thr = FFMAX(band->thr, band->energy * min_snr);
  568.             band->avoid_holes = PSY_3GPP_AH_ACTIVE;
  569.         }
  570.     }
  571.  
  572.     return thr;
  573. }
  574.  
  575. #ifndef calc_thr_3gpp
  576. static void calc_thr_3gpp(const FFPsyWindowInfo *wi, const int num_bands, AacPsyChannel *pch,
  577.                           const uint8_t *band_sizes, const float *coefs)
  578. {
  579.     int i, w, g;
  580.     int start = 0;
  581.     for (w = 0; w < wi->num_windows*16; w += 16) {
  582.         for (g = 0; g < num_bands; g++) {
  583.             AacPsyBand *band = &pch->band[w+g];
  584.  
  585.             float form_factor = 0.0f;
  586.             float Temp;
  587.             band->energy = 0.0f;
  588.             for (i = 0; i < band_sizes[g]; i++) {
  589.                 band->energy += coefs[start+i] * coefs[start+i];
  590.                 form_factor  += sqrtf(fabs(coefs[start+i]));
  591.             }
  592.             Temp = band->energy > 0 ? sqrtf((float)band_sizes[g] / band->energy) : 0;
  593.             band->thr      = band->energy * 0.001258925f;
  594.             band->nz_lines = form_factor * sqrtf(Temp);
  595.  
  596.             start += band_sizes[g];
  597.         }
  598.     }
  599. }
  600. #endif /* calc_thr_3gpp */
  601.  
  602. #ifndef psy_hp_filter
  603. static void psy_hp_filter(const float *firbuf, float *hpfsmpl, const float *psy_fir_coeffs)
  604. {
  605.     int i, j;
  606.     for (i = 0; i < AAC_BLOCK_SIZE_LONG; i++) {
  607.         float sum1, sum2;
  608.         sum1 = firbuf[i + (PSY_LAME_FIR_LEN - 1) / 2];
  609.         sum2 = 0.0;
  610.         for (j = 0; j < ((PSY_LAME_FIR_LEN - 1) / 2) - 1; j += 2) {
  611.             sum1 += psy_fir_coeffs[j] * (firbuf[i + j] + firbuf[i + PSY_LAME_FIR_LEN - j]);
  612.             sum2 += psy_fir_coeffs[j + 1] * (firbuf[i + j + 1] + firbuf[i + PSY_LAME_FIR_LEN - j - 1]);
  613.         }
  614.         /* NOTE: The LAME psymodel expects it's input in the range -32768 to 32768.
  615.          *       Tuning this for normalized floats would be difficult. */
  616.         hpfsmpl[i] = (sum1 + sum2) * 32768.0f;
  617.     }
  618. }
  619. #endif /* psy_hp_filter */
  620.  
  621. /**
  622.  * Calculate band thresholds as suggested in 3GPP TS26.403
  623.  */
  624. static void psy_3gpp_analyze_channel(FFPsyContext *ctx, int channel,
  625.                                      const float *coefs, const FFPsyWindowInfo *wi)
  626. {
  627.     AacPsyContext *pctx = (AacPsyContext*) ctx->model_priv_data;
  628.     AacPsyChannel *pch  = &pctx->ch[channel];
  629.     int i, w, g;
  630.     float desired_bits, desired_pe, delta_pe, reduction= NAN, spread_en[128] = {0};
  631.     float a = 0.0f, active_lines = 0.0f, norm_fac = 0.0f;
  632.     float pe = pctx->chan_bitrate > 32000 ? 0.0f : FFMAX(50.0f, 100.0f - pctx->chan_bitrate * 100.0f / 32000.0f);
  633.     const int      num_bands   = ctx->num_bands[wi->num_windows == 8];
  634.     const uint8_t *band_sizes  = ctx->bands[wi->num_windows == 8];
  635.     AacPsyCoeffs  *coeffs      = pctx->psy_coef[wi->num_windows == 8];
  636.     const float avoid_hole_thr = wi->num_windows == 8 ? PSY_3GPP_AH_THR_SHORT : PSY_3GPP_AH_THR_LONG;
  637.  
  638.     //calculate energies, initial thresholds and related values - 5.4.2 "Threshold Calculation"
  639.     calc_thr_3gpp(wi, num_bands, pch, band_sizes, coefs);
  640.  
  641.     //modify thresholds and energies - spread, threshold in quiet, pre-echo control
  642.     for (w = 0; w < wi->num_windows*16; w += 16) {
  643.         AacPsyBand *bands = &pch->band[w];
  644.  
  645.         /* 5.4.2.3 "Spreading" & 5.4.3 "Spread Energy Calculation" */
  646.         spread_en[0] = bands[0].energy;
  647.         for (g = 1; g < num_bands; g++) {
  648.             bands[g].thr   = FFMAX(bands[g].thr,    bands[g-1].thr * coeffs[g].spread_hi[0]);
  649.             spread_en[w+g] = FFMAX(bands[g].energy, spread_en[w+g-1] * coeffs[g].spread_hi[1]);
  650.         }
  651.         for (g = num_bands - 2; g >= 0; g--) {
  652.             bands[g].thr   = FFMAX(bands[g].thr,   bands[g+1].thr * coeffs[g].spread_low[0]);
  653.             spread_en[w+g] = FFMAX(spread_en[w+g], spread_en[w+g+1] * coeffs[g].spread_low[1]);
  654.         }
  655.         //5.4.2.4 "Threshold in quiet"
  656.         for (g = 0; g < num_bands; g++) {
  657.             AacPsyBand *band = &bands[g];
  658.  
  659.             band->thr_quiet = band->thr = FFMAX(band->thr, coeffs[g].ath);
  660.             //5.4.2.5 "Pre-echo control"
  661.             if (!(wi->window_type[0] == LONG_STOP_SEQUENCE || (wi->window_type[1] == LONG_START_SEQUENCE && !w)))
  662.                 band->thr = FFMAX(PSY_3GPP_RPEMIN*band->thr, FFMIN(band->thr,
  663.                                   PSY_3GPP_RPELEV*pch->prev_band[w+g].thr_quiet));
  664.  
  665.             /* 5.6.1.3.1 "Preparatory steps of the perceptual entropy calculation" */
  666.             pe += calc_pe_3gpp(band);
  667.             a  += band->pe_const;
  668.             active_lines += band->active_lines;
  669.  
  670.             /* 5.6.1.3.3 "Selection of the bands for avoidance of holes" */
  671.             if (spread_en[w+g] * avoid_hole_thr > band->energy || coeffs[g].min_snr > 1.0f)
  672.                 band->avoid_holes = PSY_3GPP_AH_NONE;
  673.             else
  674.                 band->avoid_holes = PSY_3GPP_AH_INACTIVE;
  675.         }
  676.     }
  677.  
  678.     /* 5.6.1.3.2 "Calculation of the desired perceptual entropy" */
  679.     ctx->ch[channel].entropy = pe;
  680.     desired_bits = calc_bit_demand(pctx, pe, ctx->bitres.bits, ctx->bitres.size, wi->num_windows == 8);
  681.     desired_pe = PSY_3GPP_BITS_TO_PE(desired_bits);
  682.     /* NOTE: PE correction is kept simple. During initial testing it had very
  683.      *       little effect on the final bitrate. Probably a good idea to come
  684.      *       back and do more testing later.
  685.      */
  686.     if (ctx->bitres.bits > 0)
  687.         desired_pe *= av_clipf(pctx->pe.previous / PSY_3GPP_BITS_TO_PE(ctx->bitres.bits),
  688.                                0.85f, 1.15f);
  689.     pctx->pe.previous = PSY_3GPP_BITS_TO_PE(desired_bits);
  690.  
  691.     if (desired_pe < pe) {
  692.         /* 5.6.1.3.4 "First Estimation of the reduction value" */
  693.         for (w = 0; w < wi->num_windows*16; w += 16) {
  694.             reduction = calc_reduction_3gpp(a, desired_pe, pe, active_lines);
  695.             pe = 0.0f;
  696.             a  = 0.0f;
  697.             active_lines = 0.0f;
  698.             for (g = 0; g < num_bands; g++) {
  699.                 AacPsyBand *band = &pch->band[w+g];
  700.  
  701.                 band->thr = calc_reduced_thr_3gpp(band, coeffs[g].min_snr, reduction);
  702.                 /* recalculate PE */
  703.                 pe += calc_pe_3gpp(band);
  704.                 a  += band->pe_const;
  705.                 active_lines += band->active_lines;
  706.             }
  707.         }
  708.  
  709.         /* 5.6.1.3.5 "Second Estimation of the reduction value" */
  710.         for (i = 0; i < 2; i++) {
  711.             float pe_no_ah = 0.0f, desired_pe_no_ah;
  712.             active_lines = a = 0.0f;
  713.             for (w = 0; w < wi->num_windows*16; w += 16) {
  714.                 for (g = 0; g < num_bands; g++) {
  715.                     AacPsyBand *band = &pch->band[w+g];
  716.  
  717.                     if (band->avoid_holes != PSY_3GPP_AH_ACTIVE) {
  718.                         pe_no_ah += band->pe;
  719.                         a        += band->pe_const;
  720.                         active_lines += band->active_lines;
  721.                     }
  722.                 }
  723.             }
  724.             desired_pe_no_ah = FFMAX(desired_pe - (pe - pe_no_ah), 0.0f);
  725.             if (active_lines > 0.0f)
  726.                 reduction = calc_reduction_3gpp(a, desired_pe_no_ah, pe_no_ah, active_lines);
  727.  
  728.             pe = 0.0f;
  729.             for (w = 0; w < wi->num_windows*16; w += 16) {
  730.                 for (g = 0; g < num_bands; g++) {
  731.                     AacPsyBand *band = &pch->band[w+g];
  732.  
  733.                     if (active_lines > 0.0f)
  734.                         band->thr = calc_reduced_thr_3gpp(band, coeffs[g].min_snr, reduction);
  735.                     pe += calc_pe_3gpp(band);
  736.                     if (band->thr > 0.0f)
  737.                         band->norm_fac = band->active_lines / band->thr;
  738.                     else
  739.                         band->norm_fac = 0.0f;
  740.                     norm_fac += band->norm_fac;
  741.                 }
  742.             }
  743.             delta_pe = desired_pe - pe;
  744.             if (fabs(delta_pe) > 0.05f * desired_pe)
  745.                 break;
  746.         }
  747.  
  748.         if (pe < 1.15f * desired_pe) {
  749.             /* 6.6.1.3.6 "Final threshold modification by linearization" */
  750.             norm_fac = 1.0f / norm_fac;
  751.             for (w = 0; w < wi->num_windows*16; w += 16) {
  752.                 for (g = 0; g < num_bands; g++) {
  753.                     AacPsyBand *band = &pch->band[w+g];
  754.  
  755.                     if (band->active_lines > 0.5f) {
  756.                         float delta_sfb_pe = band->norm_fac * norm_fac * delta_pe;
  757.                         float thr = band->thr;
  758.  
  759.                         thr *= exp2f(delta_sfb_pe / band->active_lines);
  760.                         if (thr > coeffs[g].min_snr * band->energy && band->avoid_holes == PSY_3GPP_AH_INACTIVE)
  761.                             thr = FFMAX(band->thr, coeffs[g].min_snr * band->energy);
  762.                         band->thr = thr;
  763.                     }
  764.                 }
  765.             }
  766.         } else {
  767.             /* 5.6.1.3.7 "Further perceptual entropy reduction" */
  768.             g = num_bands;
  769.             while (pe > desired_pe && g--) {
  770.                 for (w = 0; w < wi->num_windows*16; w+= 16) {
  771.                     AacPsyBand *band = &pch->band[w+g];
  772.                     if (band->avoid_holes != PSY_3GPP_AH_NONE && coeffs[g].min_snr < PSY_SNR_1DB) {
  773.                         coeffs[g].min_snr = PSY_SNR_1DB;
  774.                         band->thr = band->energy * PSY_SNR_1DB;
  775.                         pe += band->active_lines * 1.5f - band->pe;
  776.                     }
  777.                 }
  778.             }
  779.             /* TODO: allow more holes (unused without mid/side) */
  780.         }
  781.     }
  782.  
  783.     for (w = 0; w < wi->num_windows*16; w += 16) {
  784.         for (g = 0; g < num_bands; g++) {
  785.             AacPsyBand *band     = &pch->band[w+g];
  786.             FFPsyBand  *psy_band = &ctx->ch[channel].psy_bands[w+g];
  787.  
  788.             psy_band->threshold = band->thr;
  789.             psy_band->energy    = band->energy;
  790.             psy_band->spread    = band->active_lines * 2.0f / band_sizes[g];
  791.         }
  792.     }
  793.  
  794.     memcpy(pch->prev_band, pch->band, sizeof(pch->band));
  795. }
  796.  
  797. static void psy_3gpp_analyze(FFPsyContext *ctx, int channel,
  798.                                    const float **coeffs, const FFPsyWindowInfo *wi)
  799. {
  800.     int ch;
  801.     FFPsyChannelGroup *group = ff_psy_find_group(ctx, channel);
  802.  
  803.     for (ch = 0; ch < group->num_ch; ch++)
  804.         psy_3gpp_analyze_channel(ctx, channel + ch, coeffs[ch], &wi[ch]);
  805. }
  806.  
  807. static av_cold void psy_3gpp_end(FFPsyContext *apc)
  808. {
  809.     AacPsyContext *pctx = (AacPsyContext*) apc->model_priv_data;
  810.     av_freep(&pctx->ch);
  811.     av_freep(&apc->model_priv_data);
  812. }
  813.  
  814. static void lame_apply_block_type(AacPsyChannel *ctx, FFPsyWindowInfo *wi, int uselongblock)
  815. {
  816.     int blocktype = ONLY_LONG_SEQUENCE;
  817.     if (uselongblock) {
  818.         if (ctx->next_window_seq == EIGHT_SHORT_SEQUENCE)
  819.             blocktype = LONG_STOP_SEQUENCE;
  820.     } else {
  821.         blocktype = EIGHT_SHORT_SEQUENCE;
  822.         if (ctx->next_window_seq == ONLY_LONG_SEQUENCE)
  823.             ctx->next_window_seq = LONG_START_SEQUENCE;
  824.         if (ctx->next_window_seq == LONG_STOP_SEQUENCE)
  825.             ctx->next_window_seq = EIGHT_SHORT_SEQUENCE;
  826.     }
  827.  
  828.     wi->window_type[0] = ctx->next_window_seq;
  829.     ctx->next_window_seq = blocktype;
  830. }
  831.  
  832. static FFPsyWindowInfo psy_lame_window(FFPsyContext *ctx, const float *audio,
  833.                                        const float *la, int channel, int prev_type)
  834. {
  835.     AacPsyContext *pctx = (AacPsyContext*) ctx->model_priv_data;
  836.     AacPsyChannel *pch  = &pctx->ch[channel];
  837.     int grouping     = 0;
  838.     int uselongblock = 1;
  839.     int attacks[AAC_NUM_BLOCKS_SHORT + 1] = { 0 };
  840.     float clippings[AAC_NUM_BLOCKS_SHORT];
  841.     int i;
  842.     FFPsyWindowInfo wi = { { 0 } };
  843.  
  844.     if (la) {
  845.         float hpfsmpl[AAC_BLOCK_SIZE_LONG];
  846.         float const *pf = hpfsmpl;
  847.         float attack_intensity[(AAC_NUM_BLOCKS_SHORT + 1) * PSY_LAME_NUM_SUBBLOCKS];
  848.         float energy_subshort[(AAC_NUM_BLOCKS_SHORT + 1) * PSY_LAME_NUM_SUBBLOCKS];
  849.         float energy_short[AAC_NUM_BLOCKS_SHORT + 1] = { 0 };
  850.         const float *firbuf = la + (AAC_BLOCK_SIZE_SHORT/4 - PSY_LAME_FIR_LEN);
  851.         int att_sum = 0;
  852.  
  853.         /* LAME comment: apply high pass filter of fs/4 */
  854.         psy_hp_filter(firbuf, hpfsmpl, psy_fir_coeffs);
  855.  
  856.         /* Calculate the energies of each sub-shortblock */
  857.         for (i = 0; i < PSY_LAME_NUM_SUBBLOCKS; i++) {
  858.             energy_subshort[i] = pch->prev_energy_subshort[i + ((AAC_NUM_BLOCKS_SHORT - 1) * PSY_LAME_NUM_SUBBLOCKS)];
  859.             assert(pch->prev_energy_subshort[i + ((AAC_NUM_BLOCKS_SHORT - 2) * PSY_LAME_NUM_SUBBLOCKS + 1)] > 0);
  860.             attack_intensity[i] = energy_subshort[i] / pch->prev_energy_subshort[i + ((AAC_NUM_BLOCKS_SHORT - 2) * PSY_LAME_NUM_SUBBLOCKS + 1)];
  861.             energy_short[0] += energy_subshort[i];
  862.         }
  863.  
  864.         for (i = 0; i < AAC_NUM_BLOCKS_SHORT * PSY_LAME_NUM_SUBBLOCKS; i++) {
  865.             float const *const pfe = pf + AAC_BLOCK_SIZE_LONG / (AAC_NUM_BLOCKS_SHORT * PSY_LAME_NUM_SUBBLOCKS);
  866.             float p = 1.0f;
  867.             for (; pf < pfe; pf++)
  868.                 p = FFMAX(p, fabsf(*pf));
  869.             pch->prev_energy_subshort[i] = energy_subshort[i + PSY_LAME_NUM_SUBBLOCKS] = p;
  870.             energy_short[1 + i / PSY_LAME_NUM_SUBBLOCKS] += p;
  871.             /* NOTE: The indexes below are [i + 3 - 2] in the LAME source.
  872.              *       Obviously the 3 and 2 have some significance, or this would be just [i + 1]
  873.              *       (which is what we use here). What the 3 stands for is ambiguous, as it is both
  874.              *       number of short blocks, and the number of sub-short blocks.
  875.              *       It seems that LAME is comparing each sub-block to sub-block + 1 in the
  876.              *       previous block.
  877.              */
  878.             if (p > energy_subshort[i + 1])
  879.                 p = p / energy_subshort[i + 1];
  880.             else if (energy_subshort[i + 1] > p * 10.0f)
  881.                 p = energy_subshort[i + 1] / (p * 10.0f);
  882.             else
  883.                 p = 0.0;
  884.             attack_intensity[i + PSY_LAME_NUM_SUBBLOCKS] = p;
  885.         }
  886.  
  887.         /* compare energy between sub-short blocks */
  888.         for (i = 0; i < (AAC_NUM_BLOCKS_SHORT + 1) * PSY_LAME_NUM_SUBBLOCKS; i++)
  889.             if (!attacks[i / PSY_LAME_NUM_SUBBLOCKS])
  890.                 if (attack_intensity[i] > pch->attack_threshold)
  891.                     attacks[i / PSY_LAME_NUM_SUBBLOCKS] = (i % PSY_LAME_NUM_SUBBLOCKS) + 1;
  892.  
  893.         /* should have energy change between short blocks, in order to avoid periodic signals */
  894.         /* Good samples to show the effect are Trumpet test songs */
  895.         /* GB: tuned (1) to avoid too many short blocks for test sample TRUMPET */
  896.         /* RH: tuned (2) to let enough short blocks through for test sample FSOL and SNAPS */
  897.         for (i = 1; i < AAC_NUM_BLOCKS_SHORT + 1; i++) {
  898.             float const u = energy_short[i - 1];
  899.             float const v = energy_short[i];
  900.             float const m = FFMAX(u, v);
  901.             if (m < 40000) {                          /* (2) */
  902.                 if (u < 1.7f * v && v < 1.7f * u) {   /* (1) */
  903.                     if (i == 1 && attacks[0] < attacks[i])
  904.                         attacks[0] = 0;
  905.                     attacks[i] = 0;
  906.                 }
  907.             }
  908.             att_sum += attacks[i];
  909.         }
  910.  
  911.         if (attacks[0] <= pch->prev_attack)
  912.             attacks[0] = 0;
  913.  
  914.         att_sum += attacks[0];
  915.         /* 3 below indicates the previous attack happened in the last sub-block of the previous sequence */
  916.         if (pch->prev_attack == 3 || att_sum) {
  917.             uselongblock = 0;
  918.  
  919.             for (i = 1; i < AAC_NUM_BLOCKS_SHORT + 1; i++)
  920.                 if (attacks[i] && attacks[i-1])
  921.                     attacks[i] = 0;
  922.         }
  923.     } else {
  924.         /* We have no lookahead info, so just use same type as the previous sequence. */
  925.         uselongblock = !(prev_type == EIGHT_SHORT_SEQUENCE);
  926.     }
  927.  
  928.     lame_apply_block_type(pch, &wi, uselongblock);
  929.  
  930.     /* Calculate input sample maximums and evaluate clipping risk */
  931.     if (audio) {
  932.         for (i = 0; i < AAC_NUM_BLOCKS_SHORT; i++) {
  933.             const float *wbuf = audio + i * AAC_BLOCK_SIZE_SHORT;
  934.             float max = 0;
  935.             int j;
  936.             for (j = 0; j < AAC_BLOCK_SIZE_SHORT; j++)
  937.                 max = FFMAX(max, fabsf(wbuf[j]));
  938.             clippings[i] = max;
  939.         }
  940.     } else {
  941.         for (i = 0; i < 8; i++)
  942.             clippings[i] = 0;
  943.     }
  944.  
  945.     wi.window_type[1] = prev_type;
  946.     if (wi.window_type[0] != EIGHT_SHORT_SEQUENCE) {
  947.         float clipping = 0.0f;
  948.  
  949.         wi.num_windows  = 1;
  950.         wi.grouping[0]  = 1;
  951.         if (wi.window_type[0] == LONG_START_SEQUENCE)
  952.             wi.window_shape = 0;
  953.         else
  954.             wi.window_shape = 1;
  955.  
  956.         for (i = 0; i < 8; i++)
  957.             clipping = FFMAX(clipping, clippings[i]);
  958.         wi.clipping[0] = clipping;
  959.     } else {
  960.         int lastgrp = 0;
  961.  
  962.         wi.num_windows = 8;
  963.         wi.window_shape = 0;
  964.         for (i = 0; i < 8; i++) {
  965.             if (!((pch->next_grouping >> i) & 1))
  966.                 lastgrp = i;
  967.             wi.grouping[lastgrp]++;
  968.         }
  969.  
  970.         for (i = 0; i < 8; i += wi.grouping[i]) {
  971.             int w;
  972.             float clipping = 0.0f;
  973.             for (w = 0; w < wi.grouping[i] && !clipping; w++)
  974.                 clipping = FFMAX(clipping, clippings[i+w]);
  975.             wi.clipping[i] = clipping;
  976.         }
  977.     }
  978.  
  979.     /* Determine grouping, based on the location of the first attack, and save for
  980.      * the next frame.
  981.      * FIXME: Move this to analysis.
  982.      * TODO: Tune groupings depending on attack location
  983.      * TODO: Handle more than one attack in a group
  984.      */
  985.     for (i = 0; i < 9; i++) {
  986.         if (attacks[i]) {
  987.             grouping = i;
  988.             break;
  989.         }
  990.     }
  991.     pch->next_grouping = window_grouping[grouping];
  992.  
  993.     pch->prev_attack = attacks[8];
  994.  
  995.     return wi;
  996. }
  997.  
  998. const FFPsyModel ff_aac_psy_model =
  999. {
  1000.     .name    = "3GPP TS 26.403-inspired model",
  1001.     .init    = psy_3gpp_init,
  1002.     .window  = psy_lame_window,
  1003.     .analyze = psy_3gpp_analyze,
  1004.     .end     = psy_3gpp_end,
  1005. };
  1006.