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FFmpeg/libavcodec/mpegaudiodec_template.c

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  1. /*

  2.  * MPEG Audio decoder

  3.  * Copyright (c) 2001, 2002 Fabrice Bellard

  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.  * MPEG Audio decoder

  25.  */

  26. 

  27. #include "libavutil/attributes.h"

  28. #include "libavutil/avassert.h"

  29. #include "libavutil/channel_layout.h"

  30. #include "libavutil/float_dsp.h"

  31. #include "libavutil/libm.h"

  32. #include "avcodec.h"

  33. #include "get_bits.h"

  34. #include "internal.h"

  35. #include "mathops.h"

  36. #include "mpegaudiodsp.h"

  37. 

  38. /*

  39.  * TODO:

  40.  *  - test lsf / mpeg25 extensively.

  41.  */

  42. 

  43. #include "mpegaudio.h"

  44. #include "mpegaudiodecheader.h"

  45. 

  46. #define BACKSTEP_SIZE 512

  47. #define EXTRABYTES 24

  48. #define LAST_BUF_SIZE 2 * BACKSTEP_SIZE + EXTRABYTES

  49. 

  50. /* layer 3 "granule" */

  51. typedef struct GranuleDef {

  52.     uint8_t scfsi;

  53.     int part2_3_length;

  54.     int big_values;

  55.     int global_gain;

  56.     int scalefac_compress;

  57.     uint8_t block_type;

  58.     uint8_t switch_point;

  59.     int table_select[3];

  60.     int subblock_gain[3];

  61.     uint8_t scalefac_scale;

  62.     uint8_t count1table_select;

  63.     int region_size[3]; /* number of huffman codes in each region */

  64.     int preflag;

  65.     int short_start, long_end; /* long/short band indexes */

  66.     uint8_t scale_factors[40];

  67.     DECLARE_ALIGNED(16, INTFLOAT, sb_hybrid)[SBLIMIT * 18]; /* 576 samples */

  68. } GranuleDef;

  69. 

  70. typedef struct MPADecodeContext {

  71.     MPA_DECODE_HEADER

  72.     uint8_t last_buf[LAST_BUF_SIZE];

  73.     int last_buf_size;

  74.     int extrasize;

  75.     /* next header (used in free format parsing) */

  76.     uint32_t free_format_next_header;

  77.     GetBitContext gb;

  78.     GetBitContext in_gb;

  79.     DECLARE_ALIGNED(32, MPA_INT, synth_buf)[MPA_MAX_CHANNELS][512 * 2];

  80.     int synth_buf_offset[MPA_MAX_CHANNELS];

  81.     DECLARE_ALIGNED(32, INTFLOAT, sb_samples)[MPA_MAX_CHANNELS][36][SBLIMIT];

  82.     INTFLOAT mdct_buf[MPA_MAX_CHANNELS][SBLIMIT * 18]; /* previous samples, for layer 3 MDCT */

  83.     GranuleDef granules[2][2]; /* Used in Layer 3 */

  84.     int adu_mode; ///< 0 for standard mp3, 1 for adu formatted mp3

  85.     int dither_state;

  86.     int err_recognition;

  87.     AVCodecContext* avctx;

  88.     MPADSPContext mpadsp;

  89.     AVFloatDSPContext *fdsp;

  90.     AVFrame *frame;

  91. } MPADecodeContext;

  92. 

  93. #define HEADER_SIZE 4

  94. 

  95. #include "mpegaudiodata.h"

  96. #include "mpegaudiodectab.h"

  97. 

  98. /* vlc structure for decoding layer 3 huffman tables */

  99. static VLC huff_vlc[16];

  100. static VLC_TYPE huff_vlc_tables[

  101.     0 + 128 + 128 + 128 + 130 + 128 + 154 + 166 +

  102.   142 + 204 + 190 + 170 + 542 + 460 + 662 + 414

  103.   ][2];

  104. static const int huff_vlc_tables_sizes[16] = {

  105.     0,  128,  128,  128,  130,  128,  154,  166,

  106.   142,  204,  190,  170,  542,  460,  662,  414

  107. };

  108. static VLC huff_quad_vlc[2];

  109. static VLC_TYPE  huff_quad_vlc_tables[128+16][2];

  110. static const int huff_quad_vlc_tables_sizes[2] = { 128, 16 };

  111. /* computed from band_size_long */

  112. static uint16_t band_index_long[9][23];

  113. #include "mpegaudio_tablegen.h"

  114. /* intensity stereo coef table */

  115. static INTFLOAT is_table[2][16];

  116. static INTFLOAT is_table_lsf[2][2][16];

  117. static INTFLOAT csa_table[8][4];

  118. 

  119. static int16_t division_tab3[1<<6 ];

  120. static int16_t division_tab5[1<<8 ];

  121. static int16_t division_tab9[1<<11];

  122. 

  123. static int16_t * const division_tabs[4] = {

  124.     division_tab3, division_tab5, NULL, division_tab9

  125. };

  126. 

  127. /* lower 2 bits: modulo 3, higher bits: shift */

  128. static uint16_t scale_factor_modshift[64];

  129. /* [i][j]:  2^(-j/3) * FRAC_ONE * 2^(i+2) / (2^(i+2) - 1) */

  130. static int32_t scale_factor_mult[15][3];

  131. /* mult table for layer 2 group quantization */

  132. 

  133. #define SCALE_GEN(v) \

  134. { FIXR_OLD(1.0 * (v)), FIXR_OLD(0.7937005259 * (v)), FIXR_OLD(0.6299605249 * (v)) }

  135. 

  136. static const int32_t scale_factor_mult2[3][3] = {

  137.     SCALE_GEN(4.0 / 3.0), /* 3 steps */

  138.     SCALE_GEN(4.0 / 5.0), /* 5 steps */

  139.     SCALE_GEN(4.0 / 9.0), /* 9 steps */

  140. };

  141. 

  142. /**

  143.  * Convert region offsets to region sizes and truncate

  144.  * size to big_values.

  145.  */

  146. static void region_offset2size(GranuleDef *g)

  147. {

  148.     int i, k, j = 0;

  149.     g->region_size[2] = 576 / 2;

  150.     for (i = 0; i < 3; i++) {

  151.         k = FFMIN(g->region_size[i], g->big_values);

  152.         g->region_size[i] = k - j;

  153.         j = k;

  154.     }

  155. }

  156. 

  157. static void init_short_region(MPADecodeContext *s, GranuleDef *g)

  158. {

  159.     if (g->block_type == 2) {

  160.         if (s->sample_rate_index != 8)

  161.             g->region_size[0] = (36 / 2);

  162.         else

  163.             g->region_size[0] = (72 / 2);

  164.     } else {

  165.         if (s->sample_rate_index <= 2)

  166.             g->region_size[0] = (36 / 2);

  167.         else if (s->sample_rate_index != 8)

  168.             g->region_size[0] = (54 / 2);

  169.         else

  170.             g->region_size[0] = (108 / 2);

  171.     }

  172.     g->region_size[1] = (576 / 2);

  173. }

  174. 

  175. static void init_long_region(MPADecodeContext *s, GranuleDef *g,

  176.                              int ra1, int ra2)

  177. {

  178.     int l;

  179.     g->region_size[0] = band_index_long[s->sample_rate_index][ra1 + 1] >> 1;

  180.     /* should not overflow */

  181.     l = FFMIN(ra1 + ra2 + 2, 22);

  182.     g->region_size[1] = band_index_long[s->sample_rate_index][      l] >> 1;

  183. }

  184. 

  185. static void compute_band_indexes(MPADecodeContext *s, GranuleDef *g)

  186. {

  187.     if (g->block_type == 2) {

  188.         if (g->switch_point) {

  189.             if(s->sample_rate_index == 8)

  190.                 avpriv_request_sample(s->avctx, "switch point in 8khz");

  191.             /* if switched mode, we handle the 36 first samples as

  192.                 long blocks.  For 8000Hz, we handle the 72 first

  193.                 exponents as long blocks */

  194.             if (s->sample_rate_index <= 2)

  195.                 g->long_end = 8;

  196.             else

  197.                 g->long_end = 6;

  198. 

  199.             g->short_start = 3;

  200.         } else {

  201.             g->long_end    = 0;

  202.             g->short_start = 0;

  203.         }

  204.     } else {

  205.         g->short_start = 13;

  206.         g->long_end    = 22;

  207.     }

  208. }

  209. 

  210. /* layer 1 unscaling */

  211. /* n = number of bits of the mantissa minus 1 */

  212. static inline int l1_unscale(int n, int mant, int scale_factor)

  213. {

  214.     int shift, mod;

  215.     int64_t val;

  216. 

  217.     shift   = scale_factor_modshift[scale_factor];

  218.     mod     = shift & 3;

  219.     shift >>= 2;

  220.     val     = MUL64((int)(mant + (-1U << n) + 1), scale_factor_mult[n-1][mod]);

  221.     shift  += n;

  222.     /* NOTE: at this point, 1 <= shift >= 21 + 15 */

  223.     return (int)((val + (1LL << (shift - 1))) >> shift);

  224. }

  225. 

  226. static inline int l2_unscale_group(int steps, int mant, int scale_factor)

  227. {

  228.     int shift, mod, val;

  229. 

  230.     shift   = scale_factor_modshift[scale_factor];

  231.     mod     = shift & 3;

  232.     shift >>= 2;

  233. 

  234.     val = (mant - (steps >> 1)) * scale_factor_mult2[steps >> 2][mod];

  235.     /* NOTE: at this point, 0 <= shift <= 21 */

  236.     if (shift > 0)

  237.         val = (val + (1 << (shift - 1))) >> shift;

  238.     return val;

  239. }

  240. 

  241. /* compute value^(4/3) * 2^(exponent/4). It normalized to FRAC_BITS */

  242. static inline int l3_unscale(int value, int exponent)

  243. {

  244.     unsigned int m;

  245.     int e;

  246. 

  247.     e  = table_4_3_exp  [4 * value + (exponent & 3)];

  248.     m  = table_4_3_value[4 * value + (exponent & 3)];

  249.     e -= exponent >> 2;

  250. #ifdef DEBUG

  251.     if(e < 1)

  252.         av_log(NULL, AV_LOG_WARNING, "l3_unscale: e is %d\n", e);

  253. #endif

  254.     if (e > (SUINT)31)

  255.         return 0;

  256.     m = (m + ((1U << e)>>1)) >> e;

  257. 

  258.     return m;

  259. }

  260. 

  261. static av_cold void decode_init_static(void)

  262. {

  263.     int i, j, k;

  264.     int offset;

  265. 

  266.     /* scale factors table for layer 1/2 */

  267.     for (i = 0; i < 64; i++) {

  268.         int shift, mod;

  269.         /* 1.0 (i = 3) is normalized to 2 ^ FRAC_BITS */

  270.         shift = i / 3;

  271.         mod   = i % 3;

  272.         scale_factor_modshift[i] = mod | (shift << 2);

  273.     }

  274. 

  275.     /* scale factor multiply for layer 1 */

  276.     for (i = 0; i < 15; i++) {

  277.         int n, norm;

  278.         n = i + 2;

  279.         norm = ((INT64_C(1) << n) * FRAC_ONE) / ((1 << n) - 1);

  280.         scale_factor_mult[i][0] = MULLx(norm, FIXR(1.0          * 2.0), FRAC_BITS);

  281.         scale_factor_mult[i][1] = MULLx(norm, FIXR(0.7937005259 * 2.0), FRAC_BITS);

  282.         scale_factor_mult[i][2] = MULLx(norm, FIXR(0.6299605249 * 2.0), FRAC_BITS);

  283.         ff_dlog(NULL, "%d: norm=%x s=%x %x %x\n", i, norm,

  284.                 scale_factor_mult[i][0],

  285.                 scale_factor_mult[i][1],

  286.                 scale_factor_mult[i][2]);

  287.     }

  288. 

  289.     RENAME(ff_mpa_synth_init)(RENAME(ff_mpa_synth_window));

  290. 

  291.     /* huffman decode tables */

  292.     offset = 0;

  293.     for (i = 1; i < 16; i++) {

  294.         const HuffTable *h = &mpa_huff_tables[i];

  295.         int xsize, x, y;

  296.         uint8_t  tmp_bits [512] = { 0 };

  297.         uint16_t tmp_codes[512] = { 0 };

  298. 

  299.         xsize = h->xsize;

  300. 

  301.         j = 0;

  302.         for (x = 0; x < xsize; x++) {

  303.             for (y = 0; y < xsize; y++) {

  304.                 tmp_bits [(x << 5) | y | ((x&&y)<<4)]= h->bits [j  ];

  305.                 tmp_codes[(x << 5) | y | ((x&&y)<<4)]= h->codes[j++];

  306.             }

  307.         }

  308. 

  309.         /* XXX: fail test */

  310.         huff_vlc[i].table = huff_vlc_tables+offset;

  311.         huff_vlc[i].table_allocated = huff_vlc_tables_sizes[i];

  312.         init_vlc(&huff_vlc[i], 7, 512,

  313.                  tmp_bits, 1, 1, tmp_codes, 2, 2,

  314.                  INIT_VLC_USE_NEW_STATIC);

  315.         offset += huff_vlc_tables_sizes[i];

  316.     }

  317.     av_assert0(offset == FF_ARRAY_ELEMS(huff_vlc_tables));

  318. 

  319.     offset = 0;

  320.     for (i = 0; i < 2; i++) {

  321.         huff_quad_vlc[i].table = huff_quad_vlc_tables+offset;

  322.         huff_quad_vlc[i].table_allocated = huff_quad_vlc_tables_sizes[i];

  323.         init_vlc(&huff_quad_vlc[i], i == 0 ? 7 : 4, 16,

  324.                  mpa_quad_bits[i], 1, 1, mpa_quad_codes[i], 1, 1,

  325.                  INIT_VLC_USE_NEW_STATIC);

  326.         offset += huff_quad_vlc_tables_sizes[i];

  327.     }

  328.     av_assert0(offset == FF_ARRAY_ELEMS(huff_quad_vlc_tables));

  329. 

  330.     for (i = 0; i < 9; i++) {

  331.         k = 0;

  332.         for (j = 0; j < 22; j++) {

  333.             band_index_long[i][j] = k;

  334.             k += band_size_long[i][j];

  335.         }

  336.         band_index_long[i][22] = k;

  337.     }

  338. 

  339.     /* compute n ^ (4/3) and store it in mantissa/exp format */

  340. 

  341.     mpegaudio_tableinit();

  342. 

  343.     for (i = 0; i < 4; i++) {

  344.         if (ff_mpa_quant_bits[i] < 0) {

  345.             for (j = 0; j < (1 << (-ff_mpa_quant_bits[i]+1)); j++) {

  346.                 int val1, val2, val3, steps;

  347.                 int val = j;

  348.                 steps   = ff_mpa_quant_steps[i];

  349.                 val1    = val % steps;

  350.                 val    /= steps;

  351.                 val2    = val % steps;

  352.                 val3    = val / steps;

  353.                 division_tabs[i][j] = val1 + (val2 << 4) + (val3 << 8);

  354.             }

  355.         }

  356.     }

  357. 

  358. 

  359.     for (i = 0; i < 7; i++) {

  360.         float f;

  361.         INTFLOAT v;

  362.         if (i != 6) {

  363.             f = tan((double)i * M_PI / 12.0);

  364.             v = FIXR(f / (1.0 + f));

  365.         } else {

  366.             v = FIXR(1.0);

  367.         }

  368.         is_table[0][    i] = v;

  369.         is_table[1][6 - i] = v;

  370.     }

  371.     /* invalid values */

  372.     for (i = 7; i < 16; i++)

  373.         is_table[0][i] = is_table[1][i] = 0.0;

  374. 

  375.     for (i = 0; i < 16; i++) {

  376.         double f;

  377.         int e, k;

  378. 

  379.         for (j = 0; j < 2; j++) {

  380.             e = -(j + 1) * ((i + 1) >> 1);

  381.             f = exp2(e / 4.0);

  382.             k = i & 1;

  383.             is_table_lsf[j][k ^ 1][i] = FIXR(f);

  384.             is_table_lsf[j][k    ][i] = FIXR(1.0);

  385.             ff_dlog(NULL, "is_table_lsf %d %d: %f %f\n",

  386.                     i, j, (float) is_table_lsf[j][0][i],

  387.                     (float) is_table_lsf[j][1][i]);

  388.         }

  389.     }

  390. 

  391.     for (i = 0; i < 8; i++) {

  392.         double ci, cs, ca;

  393.         ci = ci_table[i];

  394.         cs = 1.0 / sqrt(1.0 + ci * ci);

  395.         ca = cs * ci;

  396. #if !USE_FLOATS

  397.         csa_table[i][0] = FIXHR(cs/4);

  398.         csa_table[i][1] = FIXHR(ca/4);

  399.         csa_table[i][2] = FIXHR(ca/4) + FIXHR(cs/4);

  400.         csa_table[i][3] = FIXHR(ca/4) - FIXHR(cs/4);

  401. #else

  402.         csa_table[i][0] = cs;

  403.         csa_table[i][1] = ca;

  404.         csa_table[i][2] = ca + cs;

  405.         csa_table[i][3] = ca - cs;

  406. #endif

  407.     }

  408. }

  409. 

  410. #if USE_FLOATS

  411. static av_cold int decode_close(AVCodecContext * avctx)

  412. {

  413.     MPADecodeContext *s = avctx->priv_data;

  414.     av_freep(&s->fdsp);

  415. 

  416.     return 0;

  417. }

  418. #endif

  419. 

  420. static av_cold int decode_init(AVCodecContext * avctx)

  421. {

  422.     static int initialized_tables = 0;

  423.     MPADecodeContext *s = avctx->priv_data;

  424. 

  425.     if (!initialized_tables) {

  426.         decode_init_static();

  427.         initialized_tables = 1;

  428.     }

  429. 

  430.     s->avctx = avctx;

  431. 

  432. #if USE_FLOATS

  433.     s->fdsp = avpriv_float_dsp_alloc(avctx->flags & AV_CODEC_FLAG_BITEXACT);

  434.     if (!s->fdsp)

  435.         return AVERROR(ENOMEM);

  436. #endif

  437. 

  438.     ff_mpadsp_init(&s->mpadsp);

  439. 

  440.     if (avctx->request_sample_fmt == OUT_FMT &&

  441.         avctx->codec_id != AV_CODEC_ID_MP3ON4)

  442.         avctx->sample_fmt = OUT_FMT;

  443.     else

  444.         avctx->sample_fmt = OUT_FMT_P;

  445.     s->err_recognition = avctx->err_recognition;

  446. 

  447.     if (avctx->codec_id == AV_CODEC_ID_MP3ADU)

  448.         s->adu_mode = 1;

  449. 

  450.     return 0;

  451. }

  452. 

  453. #define C3 FIXHR(0.86602540378443864676/2)

  454. #define C4 FIXHR(0.70710678118654752439/2) //0.5 / cos(pi*(9)/36)

  455. #define C5 FIXHR(0.51763809020504152469/2) //0.5 / cos(pi*(5)/36)

  456. #define C6 FIXHR(1.93185165257813657349/4) //0.5 / cos(pi*(15)/36)

  457. 

  458. /* 12 points IMDCT. We compute it "by hand" by factorizing obvious

  459.    cases. */

  460. static void imdct12(INTFLOAT *out, SUINTFLOAT *in)

  461. {

  462.     SUINTFLOAT in0, in1, in2, in3, in4, in5, t1, t2;

  463. 

  464.     in0  = in[0*3];

  465.     in1  = in[1*3] + in[0*3];

  466.     in2  = in[2*3] + in[1*3];

  467.     in3  = in[3*3] + in[2*3];

  468.     in4  = in[4*3] + in[3*3];

  469.     in5  = in[5*3] + in[4*3];

  470.     in5 += in3;

  471.     in3 += in1;

  472. 

  473.     in2  = MULH3(in2, C3, 2);

  474.     in3  = MULH3(in3, C3, 4);

  475. 

  476.     t1   = in0 - in4;

  477.     t2   = MULH3(in1 - in5, C4, 2);

  478. 

  479.     out[ 7] =

  480.     out[10] = t1 + t2;

  481.     out[ 1] =

  482.     out[ 4] = t1 - t2;

  483. 

  484.     in0    += SHR(in4, 1);

  485.     in4     = in0 + in2;

  486.     in5    += 2*in1;

  487.     in1     = MULH3(in5 + in3, C5, 1);

  488.     out[ 8] =

  489.     out[ 9] = in4 + in1;

  490.     out[ 2] =

  491.     out[ 3] = in4 - in1;

  492. 

  493.     in0    -= in2;

  494.     in5     = MULH3(in5 - in3, C6, 2);

  495.     out[ 0] =

  496.     out[ 5] = in0 - in5;

  497.     out[ 6] =

  498.     out[11] = in0 + in5;

  499. }

  500. 

  501. /* return the number of decoded frames */

  502. static int mp_decode_layer1(MPADecodeContext *s)

  503. {

  504.     int bound, i, v, n, ch, j, mant;

  505.     uint8_t allocation[MPA_MAX_CHANNELS][SBLIMIT];

  506.     uint8_t scale_factors[MPA_MAX_CHANNELS][SBLIMIT];

  507. 

  508.     if (s->mode == MPA_JSTEREO)

  509.         bound = (s->mode_ext + 1) * 4;

  510.     else

  511.         bound = SBLIMIT;

  512. 

  513.     /* allocation bits */

  514.     for (i = 0; i < bound; i++) {

  515.         for (ch = 0; ch < s->nb_channels; ch++) {

  516.             allocation[ch][i] = get_bits(&s->gb, 4);

  517.         }

  518.     }

  519.     for (i = bound; i < SBLIMIT; i++)

  520.         allocation[0][i] = get_bits(&s->gb, 4);

  521. 

  522.     /* scale factors */

  523.     for (i = 0; i < bound; i++) {

  524.         for (ch = 0; ch < s->nb_channels; ch++) {

  525.             if (allocation[ch][i])

  526.                 scale_factors[ch][i] = get_bits(&s->gb, 6);

  527.         }

  528.     }

  529.     for (i = bound; i < SBLIMIT; i++) {

  530.         if (allocation[0][i]) {

  531.             scale_factors[0][i] = get_bits(&s->gb, 6);

  532.             scale_factors[1][i] = get_bits(&s->gb, 6);

  533.         }

  534.     }

  535. 

  536.     /* compute samples */

  537.     for (j = 0; j < 12; j++) {

  538.         for (i = 0; i < bound; i++) {

  539.             for (ch = 0; ch < s->nb_channels; ch++) {

  540.                 n = allocation[ch][i];

  541.                 if (n) {

  542.                     mant = get_bits(&s->gb, n + 1);

  543.                     v = l1_unscale(n, mant, scale_factors[ch][i]);

  544.                 } else {

  545.                     v = 0;

  546.                 }

  547.                 s->sb_samples[ch][j][i] = v;

  548.             }

  549.         }

  550.         for (i = bound; i < SBLIMIT; i++) {

  551.             n = allocation[0][i];

  552.             if (n) {

  553.                 mant = get_bits(&s->gb, n + 1);

  554.                 v = l1_unscale(n, mant, scale_factors[0][i]);

  555.                 s->sb_samples[0][j][i] = v;

  556.                 v = l1_unscale(n, mant, scale_factors[1][i]);

  557.                 s->sb_samples[1][j][i] = v;

  558.             } else {

  559.                 s->sb_samples[0][j][i] = 0;

  560.                 s->sb_samples[1][j][i] = 0;

  561.             }

  562.         }

  563.     }

  564.     return 12;

  565. }

  566. 

  567. static int mp_decode_layer2(MPADecodeContext *s)

  568. {

  569.     int sblimit; /* number of used subbands */

  570.     const unsigned char *alloc_table;

  571.     int table, bit_alloc_bits, i, j, ch, bound, v;

  572.     unsigned char bit_alloc[MPA_MAX_CHANNELS][SBLIMIT];

  573.     unsigned char scale_code[MPA_MAX_CHANNELS][SBLIMIT];

  574.     unsigned char scale_factors[MPA_MAX_CHANNELS][SBLIMIT][3], *sf;

  575.     int scale, qindex, bits, steps, k, l, m, b;

  576. 

  577.     /* select decoding table */

  578.     table = ff_mpa_l2_select_table(s->bit_rate / 1000, s->nb_channels,

  579.                                    s->sample_rate, s->lsf);

  580.     sblimit     = ff_mpa_sblimit_table[table];

  581.     alloc_table = ff_mpa_alloc_tables[table];

  582. 

  583.     if (s->mode == MPA_JSTEREO)

  584.         bound = (s->mode_ext + 1) * 4;

  585.     else

  586.         bound = sblimit;

  587. 

  588.     ff_dlog(s->avctx, "bound=%d sblimit=%d\n", bound, sblimit);

  589. 

  590.     /* sanity check */

  591.     if (bound > sblimit)

  592.         bound = sblimit;

  593. 

  594.     /* parse bit allocation */

  595.     j = 0;

  596.     for (i = 0; i < bound; i++) {

  597.         bit_alloc_bits = alloc_table[j];

  598.         for (ch = 0; ch < s->nb_channels; ch++)

  599.             bit_alloc[ch][i] = get_bits(&s->gb, bit_alloc_bits);

  600.         j += 1 << bit_alloc_bits;

  601.     }

  602.     for (i = bound; i < sblimit; i++) {

  603.         bit_alloc_bits = alloc_table[j];

  604.         v = get_bits(&s->gb, bit_alloc_bits);

  605.         bit_alloc[0][i] = v;

  606.         bit_alloc[1][i] = v;

  607.         j += 1 << bit_alloc_bits;

  608.     }

  609. 

  610.     /* scale codes */

  611.     for (i = 0; i < sblimit; i++) {

  612.         for (ch = 0; ch < s->nb_channels; ch++) {

  613.             if (bit_alloc[ch][i])

  614.                 scale_code[ch][i] = get_bits(&s->gb, 2);

  615.         }

  616.     }

  617. 

  618.     /* scale factors */

  619.     for (i = 0; i < sblimit; i++) {

  620.         for (ch = 0; ch < s->nb_channels; ch++) {

  621.             if (bit_alloc[ch][i]) {

  622.                 sf = scale_factors[ch][i];

  623.                 switch (scale_code[ch][i]) {

  624.                 default:

  625.                 case 0:

  626.                     sf[0] = get_bits(&s->gb, 6);

  627.                     sf[1] = get_bits(&s->gb, 6);

  628.                     sf[2] = get_bits(&s->gb, 6);

  629.                     break;

  630.                 case 2:

  631.                     sf[0] = get_bits(&s->gb, 6);

  632.                     sf[1] = sf[0];

  633.                     sf[2] = sf[0];

  634.                     break;

  635.                 case 1:

  636.                     sf[0] = get_bits(&s->gb, 6);

  637.                     sf[2] = get_bits(&s->gb, 6);

  638.                     sf[1] = sf[0];

  639.                     break;

  640.                 case 3:

  641.                     sf[0] = get_bits(&s->gb, 6);

  642.                     sf[2] = get_bits(&s->gb, 6);

  643.                     sf[1] = sf[2];

  644.                     break;

  645.                 }

  646.             }

  647.         }

  648.     }

  649. 

  650.     /* samples */

  651.     for (k = 0; k < 3; k++) {

  652.         for (l = 0; l < 12; l += 3) {

  653.             j = 0;

  654.             for (i = 0; i < bound; i++) {

  655.                 bit_alloc_bits = alloc_table[j];

  656.                 for (ch = 0; ch < s->nb_channels; ch++) {

  657.                     b = bit_alloc[ch][i];

  658.                     if (b) {

  659.                         scale = scale_factors[ch][i][k];

  660.                         qindex = alloc_table[j+b];

  661.                         bits = ff_mpa_quant_bits[qindex];

  662.                         if (bits < 0) {

  663.                             int v2;

  664.                             /* 3 values at the same time */

  665.                             v = get_bits(&s->gb, -bits);

  666.                             v2 = division_tabs[qindex][v];

  667.                             steps  = ff_mpa_quant_steps[qindex];

  668. 

  669.                             s->sb_samples[ch][k * 12 + l + 0][i] =

  670.                                 l2_unscale_group(steps,  v2       & 15, scale);

  671.                             s->sb_samples[ch][k * 12 + l + 1][i] =

  672.                                 l2_unscale_group(steps, (v2 >> 4) & 15, scale);

  673.                             s->sb_samples[ch][k * 12 + l + 2][i] =

  674.                                 l2_unscale_group(steps,  v2 >> 8      , scale);

  675.                         } else {

  676.                             for (m = 0; m < 3; m++) {

  677.                                 v = get_bits(&s->gb, bits);

  678.                                 v = l1_unscale(bits - 1, v, scale);

  679.                                 s->sb_samples[ch][k * 12 + l + m][i] = v;

  680.                             }

  681.                         }

  682.                     } else {

  683.                         s->sb_samples[ch][k * 12 + l + 0][i] = 0;

  684.                         s->sb_samples[ch][k * 12 + l + 1][i] = 0;

  685.                         s->sb_samples[ch][k * 12 + l + 2][i] = 0;

  686.                     }

  687.                 }

  688.                 /* next subband in alloc table */

  689.                 j += 1 << bit_alloc_bits;

  690.             }

  691.             /* XXX: find a way to avoid this duplication of code */

  692.             for (i = bound; i < sblimit; i++) {

  693.                 bit_alloc_bits = alloc_table[j];

  694.                 b = bit_alloc[0][i];

  695.                 if (b) {

  696.                     int mant, scale0, scale1;

  697.                     scale0 = scale_factors[0][i][k];

  698.                     scale1 = scale_factors[1][i][k];

  699.                     qindex = alloc_table[j+b];

  700.                     bits = ff_mpa_quant_bits[qindex];

  701.                     if (bits < 0) {

  702.                         /* 3 values at the same time */

  703.                         v = get_bits(&s->gb, -bits);

  704.                         steps = ff_mpa_quant_steps[qindex];

  705.                         mant = v % steps;

  706.                         v = v / steps;

  707.                         s->sb_samples[0][k * 12 + l + 0][i] =

  708.                             l2_unscale_group(steps, mant, scale0);

  709.                         s->sb_samples[1][k * 12 + l + 0][i] =

  710.                             l2_unscale_group(steps, mant, scale1);

  711.                         mant = v % steps;

  712.                         v = v / steps;

  713.                         s->sb_samples[0][k * 12 + l + 1][i] =

  714.                             l2_unscale_group(steps, mant, scale0);

  715.                         s->sb_samples[1][k * 12 + l + 1][i] =

  716.                             l2_unscale_group(steps, mant, scale1);

  717.                         s->sb_samples[0][k * 12 + l + 2][i] =

  718.                             l2_unscale_group(steps, v, scale0);

  719.                         s->sb_samples[1][k * 12 + l + 2][i] =

  720.                             l2_unscale_group(steps, v, scale1);

  721.                     } else {

  722.                         for (m = 0; m < 3; m++) {

  723.                             mant = get_bits(&s->gb, bits);

  724.                             s->sb_samples[0][k * 12 + l + m][i] =

  725.                                 l1_unscale(bits - 1, mant, scale0);

  726.                             s->sb_samples[1][k * 12 + l + m][i] =

  727.                                 l1_unscale(bits - 1, mant, scale1);

  728.                         }

  729.                     }

  730.                 } else {

  731.                     s->sb_samples[0][k * 12 + l + 0][i] = 0;

  732.                     s->sb_samples[0][k * 12 + l + 1][i] = 0;

  733.                     s->sb_samples[0][k * 12 + l + 2][i] = 0;

  734.                     s->sb_samples[1][k * 12 + l + 0][i] = 0;

  735.                     s->sb_samples[1][k * 12 + l + 1][i] = 0;

  736.                     s->sb_samples[1][k * 12 + l + 2][i] = 0;

  737.                 }

  738.                 /* next subband in alloc table */

  739.                 j += 1 << bit_alloc_bits;

  740.             }

  741.             /* fill remaining samples to zero */

  742.             for (i = sblimit; i < SBLIMIT; i++) {

  743.                 for (ch = 0; ch < s->nb_channels; ch++) {

  744.                     s->sb_samples[ch][k * 12 + l + 0][i] = 0;

  745.                     s->sb_samples[ch][k * 12 + l + 1][i] = 0;

  746.                     s->sb_samples[ch][k * 12 + l + 2][i] = 0;

  747.                 }

  748.             }

  749.         }

  750.     }

  751.     return 3 * 12;

  752. }

  753. 

  754. #define SPLIT(dst,sf,n)             \

  755.     if (n == 3) {                   \

  756.         int m = (sf * 171) >> 9;    \

  757.         dst   = sf - 3 * m;         \

  758.         sf    = m;                  \

  759.     } else if (n == 4) {            \

  760.         dst  = sf & 3;              \

  761.         sf >>= 2;                   \

  762.     } else if (n == 5) {            \

  763.         int m = (sf * 205) >> 10;   \

  764.         dst   = sf - 5 * m;         \

  765.         sf    = m;                  \

  766.     } else if (n == 6) {            \

  767.         int m = (sf * 171) >> 10;   \

  768.         dst   = sf - 6 * m;         \

  769.         sf    = m;                  \

  770.     } else {                        \

  771.         dst = 0;                    \

  772.     }

  773. 

  774. static av_always_inline void lsf_sf_expand(int *slen, int sf, int n1, int n2,

  775.                                            int n3)

  776. {

  777.     SPLIT(slen[3], sf, n3)

  778.     SPLIT(slen[2], sf, n2)

  779.     SPLIT(slen[1], sf, n1)

  780.     slen[0] = sf;

  781. }

  782. 

  783. static void exponents_from_scale_factors(MPADecodeContext *s, GranuleDef *g,

  784.                                          int16_t *exponents)

  785. {

  786.     const uint8_t *bstab, *pretab;

  787.     int len, i, j, k, l, v0, shift, gain, gains[3];

  788.     int16_t *exp_ptr;

  789. 

  790.     exp_ptr = exponents;

  791.     gain    = g->global_gain - 210;

  792.     shift   = g->scalefac_scale + 1;

  793. 

  794.     bstab  = band_size_long[s->sample_rate_index];

  795.     pretab = mpa_pretab[g->preflag];

  796.     for (i = 0; i < g->long_end; i++) {

  797.         v0 = gain - ((g->scale_factors[i] + pretab[i]) << shift) + 400;

  798.         len = bstab[i];

  799.         for (j = len; j > 0; j--)

  800.             *exp_ptr++ = v0;

  801.     }

  802. 

  803.     if (g->short_start < 13) {

  804.         bstab    = band_size_short[s->sample_rate_index];

  805.         gains[0] = gain - (g->subblock_gain[0] << 3);

  806.         gains[1] = gain - (g->subblock_gain[1] << 3);

  807.         gains[2] = gain - (g->subblock_gain[2] << 3);

  808.         k        = g->long_end;

  809.         for (i = g->short_start; i < 13; i++) {

  810.             len = bstab[i];

  811.             for (l = 0; l < 3; l++) {

  812.                 v0 = gains[l] - (g->scale_factors[k++] << shift) + 400;

  813.                 for (j = len; j > 0; j--)

  814.                     *exp_ptr++ = v0;

  815.             }

  816.         }

  817.     }

  818. }

  819. 

  820. static void switch_buffer(MPADecodeContext *s, int *pos, int *end_pos,

  821.                           int *end_pos2)

  822. {

  823.     if (s->in_gb.buffer && *pos >= s->gb.size_in_bits - s->extrasize * 8) {

  824.         s->gb           = s->in_gb;

  825.         s->in_gb.buffer = NULL;

  826.         s->extrasize    = 0;

  827.         av_assert2((get_bits_count(&s->gb) & 7) == 0);

  828.         skip_bits_long(&s->gb, *pos - *end_pos);

  829.         *end_pos2 =

  830.         *end_pos  = *end_pos2 + get_bits_count(&s->gb) - *pos;

  831.         *pos      = get_bits_count(&s->gb);

  832.     }

  833. }

  834. 

  835. /* Following is an optimized code for

  836.             INTFLOAT v = *src

  837.             if(get_bits1(&s->gb))

  838.                 v = -v;

  839.             *dst = v;

  840. */

  841. #if USE_FLOATS

  842. #define READ_FLIP_SIGN(dst,src)                     \

  843.     v = AV_RN32A(src) ^ (get_bits1(&s->gb) << 31);  \

  844.     AV_WN32A(dst, v);

  845. #else

  846. #define READ_FLIP_SIGN(dst,src)     \

  847.     v      = -get_bits1(&s->gb);    \

  848.     *(dst) = (*(src) ^ v) - v;

  849. #endif

  850. 

  851. static int huffman_decode(MPADecodeContext *s, GranuleDef *g,

  852.                           int16_t *exponents, int end_pos2)

  853. {

  854.     int s_index;

  855.     int i;

  856.     int last_pos, bits_left;

  857.     VLC *vlc;

  858.     int end_pos = FFMIN(end_pos2, s->gb.size_in_bits - s->extrasize * 8);

  859. 

  860.     /* low frequencies (called big values) */

  861.     s_index = 0;

  862.     for (i = 0; i < 3; i++) {

  863.         int j, k, l, linbits;

  864.         j = g->region_size[i];

  865.         if (j == 0)

  866.             continue;

  867.         /* select vlc table */

  868.         k       = g->table_select[i];

  869.         l       = mpa_huff_data[k][0];

  870.         linbits = mpa_huff_data[k][1];

  871.         vlc     = &huff_vlc[l];

  872. 

  873.         if (!l) {

  874.             memset(&g->sb_hybrid[s_index], 0, sizeof(*g->sb_hybrid) * 2 * j);

  875.             s_index += 2 * j;

  876.             continue;

  877.         }

  878. 

  879.         /* read huffcode and compute each couple */

  880.         for (; j > 0; j--) {

  881.             int exponent, x, y;

  882.             int v;

  883.             int pos = get_bits_count(&s->gb);

  884. 

  885.             if (pos >= end_pos){

  886.                 switch_buffer(s, &pos, &end_pos, &end_pos2);

  887.                 if (pos >= end_pos)

  888.                     break;

  889.             }

  890.             y = get_vlc2(&s->gb, vlc->table, 7, 3);

  891. 

  892.             if (!y) {

  893.                 g->sb_hybrid[s_index  ] =

  894.                 g->sb_hybrid[s_index+1] = 0;

  895.                 s_index += 2;

  896.                 continue;

  897.             }

  898. 

  899.             exponent= exponents[s_index];

  900. 

  901.             ff_dlog(s->avctx, "region=%d n=%d x=%d y=%d exp=%d\n",

  902.                     i, g->region_size[i] - j, x, y, exponent);

  903.             if (y & 16) {

  904.                 x = y >> 5;

  905.                 y = y & 0x0f;

  906.                 if (x < 15) {

  907.                     READ_FLIP_SIGN(g->sb_hybrid + s_index, RENAME(expval_table)[exponent] + x)

  908.                 } else {

  909.                     x += get_bitsz(&s->gb, linbits);

  910.                     v  = l3_unscale(x, exponent);

  911.                     if (get_bits1(&s->gb))

  912.                         v = -v;

  913.                     g->sb_hybrid[s_index] = v;

  914.                 }

  915.                 if (y < 15) {

  916.                     READ_FLIP_SIGN(g->sb_hybrid + s_index + 1, RENAME(expval_table)[exponent] + y)

  917.                 } else {

  918.                     y += get_bitsz(&s->gb, linbits);

  919.                     v  = l3_unscale(y, exponent);

  920.                     if (get_bits1(&s->gb))

  921.                         v = -v;

  922.                     g->sb_hybrid[s_index+1] = v;

  923.                 }

  924.             } else {

  925.                 x = y >> 5;

  926.                 y = y & 0x0f;

  927.                 x += y;

  928.                 if (x < 15) {

  929.                     READ_FLIP_SIGN(g->sb_hybrid + s_index + !!y, RENAME(expval_table)[exponent] + x)

  930.                 } else {

  931.                     x += get_bitsz(&s->gb, linbits);

  932.                     v  = l3_unscale(x, exponent);

  933.                     if (get_bits1(&s->gb))

  934.                         v = -v;

  935.                     g->sb_hybrid[s_index+!!y] = v;

  936.                 }

  937.                 g->sb_hybrid[s_index + !y] = 0;

  938.             }

  939.             s_index += 2;

  940.         }

  941.     }

  942. 

  943.     /* high frequencies */

  944.     vlc = &huff_quad_vlc[g->count1table_select];

  945.     last_pos = 0;

  946.     while (s_index <= 572) {

  947.         int pos, code;

  948.         pos = get_bits_count(&s->gb);

  949.         if (pos >= end_pos) {

  950.             if (pos > end_pos2 && last_pos) {

  951.                 /* some encoders generate an incorrect size for this

  952.                    part. We must go back into the data */

  953.                 s_index -= 4;

  954.                 skip_bits_long(&s->gb, last_pos - pos);

  955.                 av_log(s->avctx, AV_LOG_INFO, "overread, skip %d enddists: %d %d\n", last_pos - pos, end_pos-pos, end_pos2-pos);

  956.                 if(s->err_recognition & (AV_EF_BITSTREAM|AV_EF_COMPLIANT))

  957.                     s_index=0;

  958.                 break;

  959.             }

  960.             switch_buffer(s, &pos, &end_pos, &end_pos2);

  961.             if (pos >= end_pos)

  962.                 break;

  963.         }

  964.         last_pos = pos;

  965. 

  966.         code = get_vlc2(&s->gb, vlc->table, vlc->bits, 1);

  967.         ff_dlog(s->avctx, "t=%d code=%d\n", g->count1table_select, code);

  968.         g->sb_hybrid[s_index+0] =

  969.         g->sb_hybrid[s_index+1] =

  970.         g->sb_hybrid[s_index+2] =

  971.         g->sb_hybrid[s_index+3] = 0;

  972.         while (code) {

  973.             static const int idxtab[16] = { 3,3,2,2,1,1,1,1,0,0,0,0,0,0,0,0 };

  974.             int v;

  975.             int pos = s_index + idxtab[code];

  976.             code   ^= 8 >> idxtab[code];

  977.             READ_FLIP_SIGN(g->sb_hybrid + pos, RENAME(exp_table)+exponents[pos])

  978.         }

  979.         s_index += 4;

  980.     }

  981.     /* skip extension bits */

  982.     bits_left = end_pos2 - get_bits_count(&s->gb);

  983.     if (bits_left < 0 && (s->err_recognition & (AV_EF_BUFFER|AV_EF_COMPLIANT))) {

  984.         av_log(s->avctx, AV_LOG_ERROR, "bits_left=%d\n", bits_left);

  985.         s_index=0;

  986.     } else if (bits_left > 0 && (s->err_recognition & (AV_EF_BUFFER|AV_EF_AGGRESSIVE))) {

  987.         av_log(s->avctx, AV_LOG_ERROR, "bits_left=%d\n", bits_left);

  988.         s_index = 0;

  989.     }

  990.     memset(&g->sb_hybrid[s_index], 0, sizeof(*g->sb_hybrid) * (576 - s_index));

  991.     skip_bits_long(&s->gb, bits_left);

  992. 

  993.     i = get_bits_count(&s->gb);

  994.     switch_buffer(s, &i, &end_pos, &end_pos2);

  995. 

  996.     return 0;

  997. }

  998. 

  999. /* Reorder short blocks from bitstream order to interleaved order. It

  1000.    would be faster to do it in parsing, but the code would be far more

  1001.    complicated */

  1002. static void reorder_block(MPADecodeContext *s, GranuleDef *g)

  1003. {

  1004.     int i, j, len;

  1005.     INTFLOAT *ptr, *dst, *ptr1;

  1006.     INTFLOAT tmp[576];

  1007. 

  1008.     if (g->block_type != 2)

  1009.         return;

  1010. 

  1011.     if (g->switch_point) {

  1012.         if (s->sample_rate_index != 8)

  1013.             ptr = g->sb_hybrid + 36;

  1014.         else

  1015.             ptr = g->sb_hybrid + 72;

  1016.     } else {

  1017.         ptr = g->sb_hybrid;

  1018.     }

  1019. 

  1020.     for (i = g->short_start; i < 13; i++) {

  1021.         len  = band_size_short[s->sample_rate_index][i];

  1022.         ptr1 = ptr;

  1023.         dst  = tmp;

  1024.         for (j = len; j > 0; j--) {

  1025.             *dst++ = ptr[0*len];

  1026.             *dst++ = ptr[1*len];

  1027.             *dst++ = ptr[2*len];

  1028.             ptr++;

  1029.         }

  1030.         ptr += 2 * len;

  1031.         memcpy(ptr1, tmp, len * 3 * sizeof(*ptr1));

  1032.     }

  1033. }

  1034. 

  1035. #define ISQRT2 FIXR(0.70710678118654752440)

  1036. 

  1037. static void compute_stereo(MPADecodeContext *s, GranuleDef *g0, GranuleDef *g1)

  1038. {

  1039.     int i, j, k, l;

  1040.     int sf_max, sf, len, non_zero_found;

  1041.     INTFLOAT (*is_tab)[16], *tab0, *tab1, v1, v2;

  1042.     SUINTFLOAT tmp0, tmp1;

  1043.     int non_zero_found_short[3];

  1044. 

  1045.     /* intensity stereo */

  1046.     if (s->mode_ext & MODE_EXT_I_STEREO) {

  1047.         if (!s->lsf) {

  1048.             is_tab = is_table;

  1049.             sf_max = 7;

  1050.         } else {

  1051.             is_tab = is_table_lsf[g1->scalefac_compress & 1];

  1052.             sf_max = 16;

  1053.         }

  1054. 

  1055.         tab0 = g0->sb_hybrid + 576;

  1056.         tab1 = g1->sb_hybrid + 576;

  1057. 

  1058.         non_zero_found_short[0] = 0;

  1059.         non_zero_found_short[1] = 0;

  1060.         non_zero_found_short[2] = 0;

  1061.         k = (13 - g1->short_start) * 3 + g1->long_end - 3;

  1062.         for (i = 12; i >= g1->short_start; i--) {

  1063.             /* for last band, use previous scale factor */

  1064.             if (i != 11)

  1065.                 k -= 3;

  1066.             len = band_size_short[s->sample_rate_index][i];

  1067.             for (l = 2; l >= 0; l--) {

  1068.                 tab0 -= len;

  1069.                 tab1 -= len;

  1070.                 if (!non_zero_found_short[l]) {

  1071.                     /* test if non zero band. if so, stop doing i-stereo */

  1072.                     for (j = 0; j < len; j++) {

  1073.                         if (tab1[j] != 0) {

  1074.                             non_zero_found_short[l] = 1;

  1075.                             goto found1;

  1076.                         }

  1077.                     }

  1078.                     sf = g1->scale_factors[k + l];

  1079.                     if (sf >= sf_max)

  1080.                         goto found1;

  1081. 

  1082.                     v1 = is_tab[0][sf];

  1083.                     v2 = is_tab[1][sf];

  1084.                     for (j = 0; j < len; j++) {

  1085.                         tmp0    = tab0[j];

  1086.                         tab0[j] = MULLx(tmp0, v1, FRAC_BITS);

  1087.                         tab1[j] = MULLx(tmp0, v2, FRAC_BITS);

  1088.                     }

  1089.                 } else {

  1090. found1:

  1091.                     if (s->mode_ext & MODE_EXT_MS_STEREO) {

  1092.                         /* lower part of the spectrum : do ms stereo

  1093.                            if enabled */

  1094.                         for (j = 0; j < len; j++) {

  1095.                             tmp0    = tab0[j];

  1096.                             tmp1    = tab1[j];

  1097.                             tab0[j] = MULLx(tmp0 + tmp1, ISQRT2, FRAC_BITS);

  1098.                             tab1[j] = MULLx(tmp0 - tmp1, ISQRT2, FRAC_BITS);

  1099.                         }

  1100.                     }

  1101.                 }

  1102.             }

  1103.         }

  1104. 

  1105.         non_zero_found = non_zero_found_short[0] |

  1106.                          non_zero_found_short[1] |

  1107.                          non_zero_found_short[2];

  1108. 

  1109.         for (i = g1->long_end - 1;i >= 0;i--) {

  1110.             len   = band_size_long[s->sample_rate_index][i];

  1111.             tab0 -= len;

  1112.             tab1 -= len;

  1113.             /* test if non zero band. if so, stop doing i-stereo */

  1114.             if (!non_zero_found) {

  1115.                 for (j = 0; j < len; j++) {

  1116.                     if (tab1[j] != 0) {

  1117.                         non_zero_found = 1;

  1118.                         goto found2;

  1119.                     }

  1120.                 }

  1121.                 /* for last band, use previous scale factor */

  1122.                 k  = (i == 21) ? 20 : i;

  1123.                 sf = g1->scale_factors[k];

  1124.                 if (sf >= sf_max)

  1125.                     goto found2;

  1126.                 v1 = is_tab[0][sf];

  1127.                 v2 = is_tab[1][sf];

  1128.                 for (j = 0; j < len; j++) {

  1129.                     tmp0    = tab0[j];

  1130.                     tab0[j] = MULLx(tmp0, v1, FRAC_BITS);

  1131.                     tab1[j] = MULLx(tmp0, v2, FRAC_BITS);

  1132.                 }

  1133.             } else {

  1134. found2:

  1135.                 if (s->mode_ext & MODE_EXT_MS_STEREO) {

  1136.                     /* lower part of the spectrum : do ms stereo

  1137.                        if enabled */

  1138.                     for (j = 0; j < len; j++) {

  1139.                         tmp0    = tab0[j];

  1140.                         tmp1    = tab1[j];

  1141.                         tab0[j] = MULLx(tmp0 + tmp1, ISQRT2, FRAC_BITS);

  1142.                         tab1[j] = MULLx(tmp0 - tmp1, ISQRT2, FRAC_BITS);

  1143.                     }

  1144.                 }

  1145.             }

  1146.         }

  1147.     } else if (s->mode_ext & MODE_EXT_MS_STEREO) {

  1148.         /* ms stereo ONLY */

  1149.         /* NOTE: the 1/sqrt(2) normalization factor is included in the

  1150.            global gain */

  1151. #if USE_FLOATS

  1152.        s->fdsp->butterflies_float(g0->sb_hybrid, g1->sb_hybrid, 576);

  1153. #else

  1154.         tab0 = g0->sb_hybrid;

  1155.         tab1 = g1->sb_hybrid;

  1156.         for (i = 0; i < 576; i++) {

  1157.             tmp0    = tab0[i];

  1158.             tmp1    = tab1[i];

  1159.             tab0[i] = tmp0 + tmp1;

  1160.             tab1[i] = tmp0 - tmp1;

  1161.         }

  1162. #endif

  1163.     }

  1164. }

  1165. 

  1166. #if USE_FLOATS

  1167. #if HAVE_MIPSFPU

  1168. #   include "mips/compute_antialias_float.h"

  1169. #endif /* HAVE_MIPSFPU */

  1170. #else

  1171. #if HAVE_MIPSDSP

  1172. #   include "mips/compute_antialias_fixed.h"

  1173. #endif /* HAVE_MIPSDSP */

  1174. #endif /* USE_FLOATS */

  1175. 

  1176. #ifndef compute_antialias

  1177. #if USE_FLOATS

  1178. #define AA(j) do {                                                      \

  1179.         float tmp0 = ptr[-1-j];                                         \

  1180.         float tmp1 = ptr[   j];                                         \

  1181.         ptr[-1-j] = tmp0 * csa_table[j][0] - tmp1 * csa_table[j][1];    \

  1182.         ptr[   j] = tmp0 * csa_table[j][1] + tmp1 * csa_table[j][0];    \

  1183.     } while (0)

  1184. #else

  1185. #define AA(j) do {                                              \

  1186.         SUINT tmp0 = ptr[-1-j];                                   \

  1187.         SUINT tmp1 = ptr[   j];                                   \

  1188.         SUINT tmp2 = MULH(tmp0 + tmp1, csa_table[j][0]);          \

  1189.         ptr[-1-j] = 4 * (tmp2 - MULH(tmp1, csa_table[j][2]));   \

  1190.         ptr[   j] = 4 * (tmp2 + MULH(tmp0, csa_table[j][3]));   \

  1191.     } while (0)

  1192. #endif

  1193. 

  1194. static void compute_antialias(MPADecodeContext *s, GranuleDef *g)

  1195. {

  1196.     INTFLOAT *ptr;

  1197.     int n, i;

  1198. 

  1199.     /* we antialias only "long" bands */

  1200.     if (g->block_type == 2) {

  1201.         if (!g->switch_point)

  1202.             return;

  1203.         /* XXX: check this for 8000Hz case */

  1204.         n = 1;

  1205.     } else {

  1206.         n = SBLIMIT - 1;

  1207.     }

  1208. 

  1209.     ptr = g->sb_hybrid + 18;

  1210.     for (i = n; i > 0; i--) {

  1211.         AA(0);

  1212.         AA(1);

  1213.         AA(2);

  1214.         AA(3);

  1215.         AA(4);

  1216.         AA(5);

  1217.         AA(6);

  1218.         AA(7);

  1219. 

  1220.         ptr += 18;

  1221.     }

  1222. }

  1223. #endif /* compute_antialias */

  1224. 

  1225. static void compute_imdct(MPADecodeContext *s, GranuleDef *g,

  1226.                           INTFLOAT *sb_samples, INTFLOAT *mdct_buf)

  1227. {

  1228.     INTFLOAT *win, *out_ptr, *ptr, *buf, *ptr1;

  1229.     INTFLOAT out2[12];

  1230.     int i, j, mdct_long_end, sblimit;

  1231. 

  1232.     /* find last non zero block */

  1233.     ptr  = g->sb_hybrid + 576;

  1234.     ptr1 = g->sb_hybrid + 2 * 18;

  1235.     while (ptr >= ptr1) {

  1236.         int32_t *p;

  1237.         ptr -= 6;

  1238.         p    = (int32_t*)ptr;

  1239.         if (p[0] | p[1] | p[2] | p[3] | p[4] | p[5])

  1240.             break;

  1241.     }

  1242.     sblimit = ((ptr - g->sb_hybrid) / 18) + 1;

  1243. 

  1244.     if (g->block_type == 2) {

  1245.         /* XXX: check for 8000 Hz */

  1246.         if (g->switch_point)

  1247.             mdct_long_end = 2;

  1248.         else

  1249.             mdct_long_end = 0;

  1250.     } else {

  1251.         mdct_long_end = sblimit;

  1252.     }

  1253. 

  1254.     s->mpadsp.RENAME(imdct36_blocks)(sb_samples, mdct_buf, g->sb_hybrid,

  1255.                                      mdct_long_end, g->switch_point,

  1256.                                      g->block_type);

  1257. 

  1258.     buf = mdct_buf + 4*18*(mdct_long_end >> 2) + (mdct_long_end & 3);

  1259.     ptr = g->sb_hybrid + 18 * mdct_long_end;

  1260. 

  1261.     for (j = mdct_long_end; j < sblimit; j++) {

  1262.         /* select frequency inversion */

  1263.         win     = RENAME(ff_mdct_win)[2 + (4  & -(j & 1))];

  1264.         out_ptr = sb_samples + j;

  1265. 

  1266.         for (i = 0; i < 6; i++) {

  1267.             *out_ptr = buf[4*i];

  1268.             out_ptr += SBLIMIT;

  1269.         }

  1270.         imdct12(out2, ptr + 0);

  1271.         for (i = 0; i < 6; i++) {

  1272.             *out_ptr     = MULH3(out2[i    ], win[i    ], 1) + buf[4*(i + 6*1)];

  1273.             buf[4*(i + 6*2)] = MULH3(out2[i + 6], win[i + 6], 1);

  1274.             out_ptr += SBLIMIT;

  1275.         }

  1276.         imdct12(out2, ptr + 1);

  1277.         for (i = 0; i < 6; i++) {

  1278.             *out_ptr     = MULH3(out2[i    ], win[i    ], 1) + buf[4*(i + 6*2)];

  1279.             buf[4*(i + 6*0)] = MULH3(out2[i + 6], win[i + 6], 1);

  1280.             out_ptr += SBLIMIT;

  1281.         }

  1282.         imdct12(out2, ptr + 2);

  1283.         for (i = 0; i < 6; i++) {

  1284.             buf[4*(i + 6*0)] = MULH3(out2[i    ], win[i    ], 1) + buf[4*(i + 6*0)];

  1285.             buf[4*(i + 6*1)] = MULH3(out2[i + 6], win[i + 6], 1);

  1286.             buf[4*(i + 6*2)] = 0;

  1287.         }

  1288.         ptr += 18;

  1289.         buf += (j&3) != 3 ? 1 : (4*18-3);

  1290.     }

  1291.     /* zero bands */

  1292.     for (j = sblimit; j < SBLIMIT; j++) {

  1293.         /* overlap */

  1294.         out_ptr = sb_samples + j;

  1295.         for (i = 0; i < 18; i++) {

  1296.             *out_ptr = buf[4*i];

  1297.             buf[4*i]   = 0;

  1298.             out_ptr += SBLIMIT;

  1299.         }

  1300.         buf += (j&3) != 3 ? 1 : (4*18-3);

  1301.     }

  1302. }

  1303. 

  1304. /* main layer3 decoding function */

  1305. static int mp_decode_layer3(MPADecodeContext *s)

  1306. {

  1307.     int nb_granules, main_data_begin;

  1308.     int gr, ch, blocksplit_flag, i, j, k, n, bits_pos;

  1309.     GranuleDef *g;

  1310.     int16_t exponents[576]; //FIXME try INTFLOAT

  1311. 

  1312.     /* read side info */

  1313.     if (s->lsf) {

  1314.         main_data_begin = get_bits(&s->gb, 8);

  1315.         skip_bits(&s->gb, s->nb_channels);

  1316.         nb_granules = 1;

  1317.     } else {

  1318.         main_data_begin = get_bits(&s->gb, 9);

  1319.         if (s->nb_channels == 2)

  1320.             skip_bits(&s->gb, 3);

  1321.         else

  1322.             skip_bits(&s->gb, 5);

  1323.         nb_granules = 2;

  1324.         for (ch = 0; ch < s->nb_channels; ch++) {

  1325.             s->granules[ch][0].scfsi = 0;/* all scale factors are transmitted */

  1326.             s->granules[ch][1].scfsi = get_bits(&s->gb, 4);

  1327.         }

  1328.     }

  1329. 

  1330.     for (gr = 0; gr < nb_granules; gr++) {

  1331.         for (ch = 0; ch < s->nb_channels; ch++) {

  1332.             ff_dlog(s->avctx, "gr=%d ch=%d: side_info\n", gr, ch);

  1333.             g = &s->granules[ch][gr];

  1334.             g->part2_3_length = get_bits(&s->gb, 12);

  1335.             g->big_values     = get_bits(&s->gb,  9);

  1336.             if (g->big_values > 288) {

  1337.                 av_log(s->avctx, AV_LOG_ERROR, "big_values too big\n");

  1338.                 return AVERROR_INVALIDDATA;

  1339.             }

  1340. 

  1341.             g->global_gain = get_bits(&s->gb, 8);

  1342.             /* if MS stereo only is selected, we precompute the

  1343.                1/sqrt(2) renormalization factor */

  1344.             if ((s->mode_ext & (MODE_EXT_MS_STEREO | MODE_EXT_I_STEREO)) ==

  1345.                 MODE_EXT_MS_STEREO)

  1346.                 g->global_gain -= 2;

  1347.             if (s->lsf)

  1348.                 g->scalefac_compress = get_bits(&s->gb, 9);

  1349.             else

  1350.                 g->scalefac_compress = get_bits(&s->gb, 4);

  1351.             blocksplit_flag = get_bits1(&s->gb);

  1352.             if (blocksplit_flag) {

  1353.                 g->block_type = get_bits(&s->gb, 2);

  1354.                 if (g->block_type == 0) {

  1355.                     av_log(s->avctx, AV_LOG_ERROR, "invalid block type\n");

  1356.                     return AVERROR_INVALIDDATA;

  1357.                 }

  1358.                 g->switch_point = get_bits1(&s->gb);

  1359.                 for (i = 0; i < 2; i++)

  1360.                     g->table_select[i] = get_bits(&s->gb, 5);

  1361.                 for (i = 0; i < 3; i++)

  1362.                     g->subblock_gain[i] = get_bits(&s->gb, 3);

  1363.                 init_short_region(s, g);

  1364.             } else {

  1365.                 int region_address1, region_address2;

  1366.                 g->block_type = 0;

  1367.                 g->switch_point = 0;

  1368.                 for (i = 0; i < 3; i++)

  1369.                     g->table_select[i] = get_bits(&s->gb, 5);

  1370.                 /* compute huffman coded region sizes */

  1371.                 region_address1 = get_bits(&s->gb, 4);

  1372.                 region_address2 = get_bits(&s->gb, 3);

  1373.                 ff_dlog(s->avctx, "region1=%d region2=%d\n",

  1374.                         region_address1, region_address2);

  1375.                 init_long_region(s, g, region_address1, region_address2);

  1376.             }

  1377.             region_offset2size(g);

  1378.             compute_band_indexes(s, g);

  1379. 

  1380.             g->preflag = 0;

  1381.             if (!s->lsf)

  1382.                 g->preflag = get_bits1(&s->gb);

  1383.             g->scalefac_scale     = get_bits1(&s->gb);

  1384.             g->count1table_select = get_bits1(&s->gb);

  1385.             ff_dlog(s->avctx, "block_type=%d switch_point=%d\n",

  1386.                     g->block_type, g->switch_point);

  1387.         }

  1388.     }

  1389. 

  1390.     if (!s->adu_mode) {

  1391.         int skip;

  1392.         const uint8_t *ptr = s->gb.buffer + (get_bits_count(&s->gb)>>3);

  1393.         s->extrasize = av_clip((get_bits_left(&s->gb) >> 3) - s->extrasize, 0,

  1394.                                FFMAX(0, LAST_BUF_SIZE - s->last_buf_size));

  1395.         av_assert1((get_bits_count(&s->gb) & 7) == 0);

  1396.         /* now we get bits from the main_data_begin offset */

  1397.         ff_dlog(s->avctx, "seekback:%d, lastbuf:%d\n",

  1398.                 main_data_begin, s->last_buf_size);

  1399. 

  1400.         memcpy(s->last_buf + s->last_buf_size, ptr, s->extrasize);

  1401.         s->in_gb = s->gb;

  1402.         init_get_bits(&s->gb, s->last_buf, (s->last_buf_size + s->extrasize) * 8);

  1403.         s->last_buf_size <<= 3;

  1404.         for (gr = 0; gr < nb_granules && (s->last_buf_size >> 3) < main_data_begin; gr++) {

  1405.             for (ch = 0; ch < s->nb_channels; ch++) {

  1406.                 g = &s->granules[ch][gr];

  1407.                 s->last_buf_size += g->part2_3_length;

  1408.                 memset(g->sb_hybrid, 0, sizeof(g->sb_hybrid));

  1409.                 compute_imdct(s, g, &s->sb_samples[ch][18 * gr][0], s->mdct_buf[ch]);

  1410.             }

  1411.         }

  1412.         skip = s->last_buf_size - 8 * main_data_begin;

  1413.         if (skip >= s->gb.size_in_bits - s->extrasize * 8 && s->in_gb.buffer) {

  1414.             skip_bits_long(&s->in_gb, skip - s->gb.size_in_bits + s->extrasize * 8);

  1415.             s->gb           = s->in_gb;

  1416.             s->in_gb.buffer = NULL;

  1417.             s->extrasize    = 0;

  1418.         } else {

  1419.             skip_bits_long(&s->gb, skip);

  1420.         }

  1421.     } else {

  1422.         gr = 0;

  1423.         s->extrasize = 0;

  1424.     }

  1425. 

  1426.     for (; gr < nb_granules; gr++) {

  1427.         for (ch = 0; ch < s->nb_channels; ch++) {

  1428.             g = &s->granules[ch][gr];

  1429.             bits_pos = get_bits_count(&s->gb);

  1430. 

  1431.             if (!s->lsf) {

  1432.                 uint8_t *sc;

  1433.                 int slen, slen1, slen2;

  1434. 

  1435.                 /* MPEG-1 scale factors */

  1436.                 slen1 = slen_table[0][g->scalefac_compress];

  1437.                 slen2 = slen_table[1][g->scalefac_compress];

  1438.                 ff_dlog(s->avctx, "slen1=%d slen2=%d\n", slen1, slen2);

  1439.                 if (g->block_type == 2) {

  1440.                     n = g->switch_point ? 17 : 18;

  1441.                     j = 0;

  1442.                     if (slen1) {

  1443.                         for (i = 0; i < n; i++)

  1444.                             g->scale_factors[j++] = get_bits(&s->gb, slen1);

  1445.                     } else {

  1446.                         for (i = 0; i < n; i++)

  1447.                             g->scale_factors[j++] = 0;

  1448.                     }

  1449.                     if (slen2) {

  1450.                         for (i = 0; i < 18; i++)

  1451.                             g->scale_factors[j++] = get_bits(&s->gb, slen2);

  1452.                         for (i = 0; i < 3; i++)

  1453.                             g->scale_factors[j++] = 0;

  1454.                     } else {

  1455.                         for (i = 0; i < 21; i++)

  1456.                             g->scale_factors[j++] = 0;

  1457.                     }

  1458.                 } else {

  1459.                     sc = s->granules[ch][0].scale_factors;

  1460.                     j = 0;

  1461.                     for (k = 0; k < 4; k++) {

  1462.                         n = k == 0 ? 6 : 5;

  1463.                         if ((g->scfsi & (0x8 >> k)) == 0) {

  1464.                             slen = (k < 2) ? slen1 : slen2;

  1465.                             if (slen) {

  1466.                                 for (i = 0; i < n; i++)

  1467.                                     g->scale_factors[j++] = get_bits(&s->gb, slen);

  1468.                             } else {

  1469.                                 for (i = 0; i < n; i++)

  1470.                                     g->scale_factors[j++] = 0;

  1471.                             }

  1472.                         } else {

  1473.                             /* simply copy from last granule */

  1474.                             for (i = 0; i < n; i++) {

  1475.                                 g->scale_factors[j] = sc[j];

  1476.                                 j++;

  1477.                             }

  1478.                         }

  1479.                     }

  1480.                     g->scale_factors[j++] = 0;

  1481.                 }

  1482.             } else {

  1483.                 int tindex, tindex2, slen[4], sl, sf;

  1484. 

  1485.                 /* LSF scale factors */

  1486.                 if (g->block_type == 2)

  1487.                     tindex = g->switch_point ? 2 : 1;

  1488.                 else

  1489.                     tindex = 0;

  1490. 

  1491.                 sf = g->scalefac_compress;

  1492.                 if ((s->mode_ext & MODE_EXT_I_STEREO) && ch == 1) {

  1493.                     /* intensity stereo case */

  1494.                     sf >>= 1;

  1495.                     if (sf < 180) {

  1496.                         lsf_sf_expand(slen, sf, 6, 6, 0);

  1497.                         tindex2 = 3;

  1498.                     } else if (sf < 244) {

  1499.                         lsf_sf_expand(slen, sf - 180, 4, 4, 0);

  1500.                         tindex2 = 4;

  1501.                     } else {

  1502.                         lsf_sf_expand(slen, sf - 244, 3, 0, 0);

  1503.                         tindex2 = 5;

  1504.                     }

  1505.                 } else {

  1506.                     /* normal case */

  1507.                     if (sf < 400) {

  1508.                         lsf_sf_expand(slen, sf, 5, 4, 4);

  1509.                         tindex2 = 0;

  1510.                     } else if (sf < 500) {

  1511.                         lsf_sf_expand(slen, sf - 400, 5, 4, 0);

  1512.                         tindex2 = 1;

  1513.                     } else {

  1514.                         lsf_sf_expand(slen, sf - 500, 3, 0, 0);

  1515.                         tindex2 = 2;

  1516.                         g->preflag = 1;

  1517.                     }

  1518.                 }

  1519. 

  1520.                 j = 0;

  1521.                 for (k = 0; k < 4; k++) {

  1522.                     n  = lsf_nsf_table[tindex2][tindex][k];

  1523.                     sl = slen[k];

  1524.                     if (sl) {

  1525.                         for (i = 0; i < n; i++)

  1526.                             g->scale_factors[j++] = get_bits(&s->gb, sl);

  1527.                     } else {

  1528.                         for (i = 0; i < n; i++)

  1529.                             g->scale_factors[j++] = 0;

  1530.                     }

  1531.                 }

  1532.                 /* XXX: should compute exact size */

  1533.                 for (; j < 40; j++)

  1534.                     g->scale_factors[j] = 0;

  1535.             }

  1536. 

  1537.             exponents_from_scale_factors(s, g, exponents);

  1538. 

  1539.             /* read Huffman coded residue */

  1540.             huffman_decode(s, g, exponents, bits_pos + g->part2_3_length);

  1541.         } /* ch */

  1542. 

  1543.         if (s->mode == MPA_JSTEREO)

  1544.             compute_stereo(s, &s->granules[0][gr], &s->granules[1][gr]);

  1545. 

  1546.         for (ch = 0; ch < s->nb_channels; ch++) {

  1547.             g = &s->granules[ch][gr];

  1548. 

  1549.             reorder_block(s, g);

  1550.             compute_antialias(s, g);

  1551.             compute_imdct(s, g, &s->sb_samples[ch][18 * gr][0], s->mdct_buf[ch]);

  1552.         }

  1553.     } /* gr */

  1554.     if (get_bits_count(&s->gb) < 0)

  1555.         skip_bits_long(&s->gb, -get_bits_count(&s->gb));

  1556.     return nb_granules * 18;

  1557. }

  1558. 

  1559. static int mp_decode_frame(MPADecodeContext *s, OUT_INT **samples,

  1560.                            const uint8_t *buf, int buf_size)

  1561. {

  1562.     int i, nb_frames, ch, ret;

  1563.     OUT_INT *samples_ptr;

  1564. 

  1565.     init_get_bits(&s->gb, buf + HEADER_SIZE, (buf_size - HEADER_SIZE) * 8);

  1566. 

  1567.     /* skip error protection field */

  1568.     if (s->error_protection)

  1569.         skip_bits(&s->gb, 16);

  1570. 

  1571.     switch(s->layer) {

  1572.     case 1:

  1573.         s->avctx->frame_size = 384;

  1574.         nb_frames = mp_decode_layer1(s);

  1575.         break;

  1576.     case 2:

  1577.         s->avctx->frame_size = 1152;

  1578.         nb_frames = mp_decode_layer2(s);

  1579.         break;

  1580.     case 3:

  1581.         s->avctx->frame_size = s->lsf ? 576 : 1152;

  1582.     default:

  1583.         nb_frames = mp_decode_layer3(s);

  1584. 

  1585.         s->last_buf_size=0;

  1586.         if (s->in_gb.buffer) {

  1587.             align_get_bits(&s->gb);

  1588.             i = (get_bits_left(&s->gb) >> 3) - s->extrasize;

  1589.             if (i >= 0 && i <= BACKSTEP_SIZE) {

  1590.                 memmove(s->last_buf, s->gb.buffer + (get_bits_count(&s->gb)>>3), i);

  1591.                 s->last_buf_size=i;

  1592.             } else

  1593.                 av_log(s->avctx, AV_LOG_ERROR, "invalid old backstep %d\n", i);

  1594.             s->gb           = s->in_gb;

  1595.             s->in_gb.buffer = NULL;

  1596.             s->extrasize    = 0;

  1597.         }

  1598. 

  1599.         align_get_bits(&s->gb);

  1600.         av_assert1((get_bits_count(&s->gb) & 7) == 0);

  1601.         i = (get_bits_left(&s->gb) >> 3) - s->extrasize;

  1602.         if (i < 0 || i > BACKSTEP_SIZE || nb_frames < 0) {

  1603.             if (i < 0)

  1604.                 av_log(s->avctx, AV_LOG_ERROR, "invalid new backstep %d\n", i);

  1605.             i = FFMIN(BACKSTEP_SIZE, buf_size - HEADER_SIZE);

  1606.         }

  1607.         av_assert1(i <= buf_size - HEADER_SIZE && i >= 0);

  1608.         memcpy(s->last_buf + s->last_buf_size, s->gb.buffer + buf_size - HEADER_SIZE - i, i);

  1609.         s->last_buf_size += i;

  1610.     }

  1611. 

  1612.     if(nb_frames < 0)

  1613.         return nb_frames;

  1614. 

  1615.     /* get output buffer */

  1616.     if (!samples) {

  1617.         av_assert0(s->frame);

  1618.         s->frame->nb_samples = s->avctx->frame_size;

  1619.         if ((ret = ff_get_buffer(s->avctx, s->frame, 0)) < 0)

  1620.             return ret;

  1621.         samples = (OUT_INT **)s->frame->extended_data;

  1622.     }

  1623. 

  1624.     /* apply the synthesis filter */

  1625.     for (ch = 0; ch < s->nb_channels; ch++) {

  1626.         int sample_stride;

  1627.         if (s->avctx->sample_fmt == OUT_FMT_P) {

  1628.             samples_ptr   = samples[ch];

  1629.             sample_stride = 1;

  1630.         } else {

  1631.             samples_ptr   = samples[0] + ch;

  1632.             sample_stride = s->nb_channels;

  1633.         }

  1634.         for (i = 0; i < nb_frames; i++) {

  1635.             RENAME(ff_mpa_synth_filter)(&s->mpadsp, s->synth_buf[ch],

  1636.                                         &(s->synth_buf_offset[ch]),

  1637.                                         RENAME(ff_mpa_synth_window),

  1638.                                         &s->dither_state, samples_ptr,

  1639.                                         sample_stride, s->sb_samples[ch][i]);

  1640.             samples_ptr += 32 * sample_stride;

  1641.         }

  1642.     }

  1643. 

  1644.     return nb_frames * 32 * sizeof(OUT_INT) * s->nb_channels;

  1645. }

  1646. 

  1647. static int decode_frame(AVCodecContext * avctx, void *data, int *got_frame_ptr,

  1648.                         AVPacket *avpkt)

  1649. {

  1650.     const uint8_t *buf  = avpkt->data;

  1651.     int buf_size        = avpkt->size;

  1652.     MPADecodeContext *s = avctx->priv_data;

  1653.     uint32_t header;

  1654.     int ret;

  1655. 

  1656.     int skipped = 0;

  1657.     while(buf_size && !*buf){

  1658.         buf++;

  1659.         buf_size--;

  1660.         skipped++;

  1661.     }

  1662. 

  1663.     if (buf_size < HEADER_SIZE)

  1664.         return AVERROR_INVALIDDATA;

  1665. 

  1666.     header = AV_RB32(buf);

  1667.     if (header>>8 == AV_RB32("TAG")>>8) {

  1668.         av_log(avctx, AV_LOG_DEBUG, "discarding ID3 tag\n");

  1669.         return buf_size + skipped;

  1670.     }

  1671.     ret = avpriv_mpegaudio_decode_header((MPADecodeHeader *)s, header);

  1672.     if (ret < 0) {

  1673.         av_log(avctx, AV_LOG_ERROR, "Header missing\n");

  1674.         return AVERROR_INVALIDDATA;

  1675.     } else if (ret == 1) {

  1676.         /* free format: prepare to compute frame size */

  1677.         s->frame_size = -1;

  1678.         return AVERROR_INVALIDDATA;

  1679.     }

  1680.     /* update codec info */

  1681.     avctx->channels       = s->nb_channels;

  1682.     avctx->channel_layout = s->nb_channels == 1 ? AV_CH_LAYOUT_MONO : AV_CH_LAYOUT_STEREO;

  1683.     if (!avctx->bit_rate)

  1684.         avctx->bit_rate = s->bit_rate;

  1685. 

  1686.     if (s->frame_size <= 0) {

  1687.         av_log(avctx, AV_LOG_ERROR, "incomplete frame\n");

  1688.         return AVERROR_INVALIDDATA;

  1689.     } else if (s->frame_size < buf_size) {

  1690.         av_log(avctx, AV_LOG_DEBUG, "incorrect frame size - multiple frames in buffer?\n");

  1691.         buf_size= s->frame_size;

  1692.     }

  1693. 

  1694.     s->frame = data;

  1695. 

  1696.     ret = mp_decode_frame(s, NULL, buf, buf_size);

  1697.     if (ret >= 0) {

  1698.         s->frame->nb_samples = avctx->frame_size;

  1699.         *got_frame_ptr       = 1;

  1700.         avctx->sample_rate   = s->sample_rate;

  1701.         //FIXME maybe move the other codec info stuff from above here too

  1702.     } else {

  1703.         av_log(avctx, AV_LOG_ERROR, "Error while decoding MPEG audio frame.\n");

  1704.         /* Only return an error if the bad frame makes up the whole packet or

  1705.          * the error is related to buffer management.

  1706.          * If there is more data in the packet, just consume the bad frame

  1707.          * instead of returning an error, which would discard the whole

  1708.          * packet. */

  1709.         *got_frame_ptr = 0;

  1710.         if (buf_size == avpkt->size || ret != AVERROR_INVALIDDATA)

  1711.             return ret;

  1712.     }

  1713.     s->frame_size = 0;

  1714.     return buf_size + skipped;

  1715. }

  1716. 

  1717. static void mp_flush(MPADecodeContext *ctx)

  1718. {

  1719.     memset(ctx->synth_buf, 0, sizeof(ctx->synth_buf));

  1720.     memset(ctx->mdct_buf, 0, sizeof(ctx->mdct_buf));

  1721.     ctx->last_buf_size = 0;

  1722.     ctx->dither_state = 0;

  1723. }

  1724. 

  1725. static void flush(AVCodecContext *avctx)

  1726. {

  1727.     mp_flush(avctx->priv_data);

  1728. }

  1729. 

  1730. #if CONFIG_MP3ADU_DECODER || CONFIG_MP3ADUFLOAT_DECODER

  1731. static int decode_frame_adu(AVCodecContext *avctx, void *data,

  1732.                             int *got_frame_ptr, AVPacket *avpkt)

  1733. {

  1734.     const uint8_t *buf  = avpkt->data;

  1735.     int buf_size        = avpkt->size;

  1736.     MPADecodeContext *s = avctx->priv_data;

  1737.     uint32_t header;

  1738.     int len, ret;

  1739.     int av_unused out_size;

  1740. 

  1741.     len = buf_size;

  1742. 

  1743.     // Discard too short frames

  1744.     if (buf_size < HEADER_SIZE) {

  1745.         av_log(avctx, AV_LOG_ERROR, "Packet is too small\n");

  1746.         return AVERROR_INVALIDDATA;

  1747.     }

  1748. 

  1749. 

  1750.     if (len > MPA_MAX_CODED_FRAME_SIZE)

  1751.         len = MPA_MAX_CODED_FRAME_SIZE;

  1752. 

  1753.     // Get header and restore sync word

  1754.     header = AV_RB32(buf) | 0xffe00000;

  1755. 

  1756.     ret = avpriv_mpegaudio_decode_header((MPADecodeHeader *)s, header);

  1757.     if (ret < 0) {

  1758.         av_log(avctx, AV_LOG_ERROR, "Invalid frame header\n");

  1759.         return ret;

  1760.     }

  1761.     /* update codec info */

  1762.     avctx->sample_rate = s->sample_rate;

  1763.     avctx->channels    = s->nb_channels;

  1764.     avctx->channel_layout = s->nb_channels == 1 ? AV_CH_LAYOUT_MONO : AV_CH_LAYOUT_STEREO;

  1765.     if (!avctx->bit_rate)

  1766.         avctx->bit_rate = s->bit_rate;

  1767. 

  1768.     s->frame_size = len;

  1769. 

  1770.     s->frame = data;

  1771. 

  1772.     ret = mp_decode_frame(s, NULL, buf, buf_size);

  1773.     if (ret < 0) {

  1774.         av_log(avctx, AV_LOG_ERROR, "Error while decoding MPEG audio frame.\n");

  1775.         return ret;

  1776.     }

  1777. 

  1778.     *got_frame_ptr = 1;

  1779. 

  1780.     return buf_size;

  1781. }

  1782. #endif /* CONFIG_MP3ADU_DECODER || CONFIG_MP3ADUFLOAT_DECODER */

  1783. 

  1784. #if CONFIG_MP3ON4_DECODER || CONFIG_MP3ON4FLOAT_DECODER

  1785. 

  1786. /**

  1787.  * Context for MP3On4 decoder

  1788.  */

  1789. typedef struct MP3On4DecodeContext {

  1790.     int frames;                     ///< number of mp3 frames per block (number of mp3 decoder instances)

  1791.     int syncword;                   ///< syncword patch

  1792.     const uint8_t *coff;            ///< channel offsets in output buffer

  1793.     MPADecodeContext *mp3decctx[5]; ///< MPADecodeContext for every decoder instance

  1794. } MP3On4DecodeContext;

  1795. 

  1796. #include "mpeg4audio.h"

  1797. 

  1798. /* Next 3 arrays are indexed by channel config number (passed via codecdata) */

  1799. 

  1800. /* number of mp3 decoder instances */

  1801. static const uint8_t mp3Frames[8] = { 0, 1, 1, 2, 3, 3, 4, 5 };

  1802. 

  1803. /* offsets into output buffer, assume output order is FL FR C LFE BL BR SL SR */

  1804. static const uint8_t chan_offset[8][5] = {

  1805.     { 0             },

  1806.     { 0             },  // C

  1807.     { 0             },  // FLR

  1808.     { 2, 0          },  // C FLR

  1809.     { 2, 0, 3       },  // C FLR BS

  1810.     { 2, 0, 3       },  // C FLR BLRS

  1811.     { 2, 0, 4, 3    },  // C FLR BLRS LFE

  1812.     { 2, 0, 6, 4, 3 },  // C FLR BLRS BLR LFE

  1813. };

  1814. 

  1815. /* mp3on4 channel layouts */

  1816. static const int16_t chan_layout[8] = {

  1817.     0,

  1818.     AV_CH_LAYOUT_MONO,

  1819.     AV_CH_LAYOUT_STEREO,

  1820.     AV_CH_LAYOUT_SURROUND,

  1821.     AV_CH_LAYOUT_4POINT0,

  1822.     AV_CH_LAYOUT_5POINT0,

  1823.     AV_CH_LAYOUT_5POINT1,

  1824.     AV_CH_LAYOUT_7POINT1

  1825. };

  1826. 

  1827. static av_cold int decode_close_mp3on4(AVCodecContext * avctx)

  1828. {

  1829.     MP3On4DecodeContext *s = avctx->priv_data;

  1830.     int i;

  1831. 

  1832.     if (s->mp3decctx[0])

  1833.         av_freep(&s->mp3decctx[0]->fdsp);

  1834. 

  1835.     for (i = 0; i < s->frames; i++)

  1836.         av_freep(&s->mp3decctx[i]);

  1837. 

  1838.     return 0;

  1839. }

  1840. 

  1841. 

  1842. static av_cold int decode_init_mp3on4(AVCodecContext * avctx)

  1843. {

  1844.     MP3On4DecodeContext *s = avctx->priv_data;

  1845.     MPEG4AudioConfig cfg;

  1846.     int i;

  1847. 

  1848.     if ((avctx->extradata_size < 2) || !avctx->extradata) {

  1849.         av_log(avctx, AV_LOG_ERROR, "Codec extradata missing or too short.\n");

  1850.         return AVERROR_INVALIDDATA;

  1851.     }

  1852. 

  1853.     avpriv_mpeg4audio_get_config(&cfg, avctx->extradata,

  1854.                                  avctx->extradata_size * 8, 1);

  1855.     if (!cfg.chan_config || cfg.chan_config > 7) {

  1856.         av_log(avctx, AV_LOG_ERROR, "Invalid channel config number.\n");

  1857.         return AVERROR_INVALIDDATA;

  1858.     }

  1859.     s->frames             = mp3Frames[cfg.chan_config];

  1860.     s->coff               = chan_offset[cfg.chan_config];

  1861.     avctx->channels       = ff_mpeg4audio_channels[cfg.chan_config];

  1862.     avctx->channel_layout = chan_layout[cfg.chan_config];

  1863. 

  1864.     if (cfg.sample_rate < 16000)

  1865.         s->syncword = 0xffe00000;

  1866.     else

  1867.         s->syncword = 0xfff00000;

  1868. 

  1869.     /* Init the first mp3 decoder in standard way, so that all tables get builded

  1870.      * We replace avctx->priv_data with the context of the first decoder so that

  1871.      * decode_init() does not have to be changed.

  1872.      * Other decoders will be initialized here copying data from the first context

  1873.      */

  1874.     // Allocate zeroed memory for the first decoder context

  1875.     s->mp3decctx[0] = av_mallocz(sizeof(MPADecodeContext));

  1876.     if (!s->mp3decctx[0])

  1877.         goto alloc_fail;

  1878.     // Put decoder context in place to make init_decode() happy

  1879.     avctx->priv_data = s->mp3decctx[0];

  1880.     decode_init(avctx);

  1881.     // Restore mp3on4 context pointer

  1882.     avctx->priv_data = s;

  1883.     s->mp3decctx[0]->adu_mode = 1; // Set adu mode

  1884. 

  1885.     /* Create a separate codec/context for each frame (first is already ok).

  1886.      * Each frame is 1 or 2 channels - up to 5 frames allowed

  1887.      */

  1888.     for (i = 1; i < s->frames; i++) {

  1889.         s->mp3decctx[i] = av_mallocz(sizeof(MPADecodeContext));

  1890.         if (!s->mp3decctx[i])

  1891.             goto alloc_fail;

  1892.         s->mp3decctx[i]->adu_mode = 1;

  1893.         s->mp3decctx[i]->avctx = avctx;

  1894.         s->mp3decctx[i]->mpadsp = s->mp3decctx[0]->mpadsp;

  1895.         s->mp3decctx[i]->fdsp = s->mp3decctx[0]->fdsp;

  1896.     }

  1897. 

  1898.     return 0;

  1899. alloc_fail:

  1900.     decode_close_mp3on4(avctx);

  1901.     return AVERROR(ENOMEM);

  1902. }

  1903. 

  1904. 

  1905. static void flush_mp3on4(AVCodecContext *avctx)

  1906. {

  1907.     int i;

  1908.     MP3On4DecodeContext *s = avctx->priv_data;

  1909. 

  1910.     for (i = 0; i < s->frames; i++)

  1911.         mp_flush(s->mp3decctx[i]);

  1912. }

  1913. 

  1914. 

  1915. static int decode_frame_mp3on4(AVCodecContext *avctx, void *data,

  1916.                                int *got_frame_ptr, AVPacket *avpkt)

  1917. {

  1918.     AVFrame *frame         = data;

  1919.     const uint8_t *buf     = avpkt->data;

  1920.     int buf_size           = avpkt->size;

  1921.     MP3On4DecodeContext *s = avctx->priv_data;

  1922.     MPADecodeContext *m;

  1923.     int fsize, len = buf_size, out_size = 0;

  1924.     uint32_t header;

  1925.     OUT_INT **out_samples;

  1926.     OUT_INT *outptr[2];

  1927.     int fr, ch, ret;

  1928. 

  1929.     /* get output buffer */

  1930.     frame->nb_samples = MPA_FRAME_SIZE;

  1931.     if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)

  1932.         return ret;

  1933.     out_samples = (OUT_INT **)frame->extended_data;

  1934. 

  1935.     // Discard too short frames

  1936.     if (buf_size < HEADER_SIZE)

  1937.         return AVERROR_INVALIDDATA;

  1938. 

  1939.     avctx->bit_rate = 0;

  1940. 

  1941.     ch = 0;

  1942.     for (fr = 0; fr < s->frames; fr++) {

  1943.         fsize = AV_RB16(buf) >> 4;

  1944.         fsize = FFMIN3(fsize, len, MPA_MAX_CODED_FRAME_SIZE);

  1945.         m     = s->mp3decctx[fr];

  1946.         av_assert1(m);

  1947. 

  1948.         if (fsize < HEADER_SIZE) {

  1949.             av_log(avctx, AV_LOG_ERROR, "Frame size smaller than header size\n");

  1950.             return AVERROR_INVALIDDATA;

  1951.         }

  1952.         header = (AV_RB32(buf) & 0x000fffff) | s->syncword; // patch header

  1953. 

  1954.         ret = avpriv_mpegaudio_decode_header((MPADecodeHeader *)m, header);

  1955.         if (ret < 0) {

  1956.             av_log(avctx, AV_LOG_ERROR, "Bad header, discard block\n");

  1957.             return AVERROR_INVALIDDATA;

  1958.         }

  1959. 

  1960.         if (ch + m->nb_channels > avctx->channels ||

  1961.             s->coff[fr] + m->nb_channels > avctx->channels) {

  1962.             av_log(avctx, AV_LOG_ERROR, "frame channel count exceeds codec "

  1963.                                         "channel count\n");

  1964.             return AVERROR_INVALIDDATA;

  1965.         }

  1966.         ch += m->nb_channels;

  1967. 

  1968.         outptr[0] = out_samples[s->coff[fr]];

  1969.         if (m->nb_channels > 1)

  1970.             outptr[1] = out_samples[s->coff[fr] + 1];

  1971. 

  1972.         if ((ret = mp_decode_frame(m, outptr, buf, fsize)) < 0) {

  1973.             av_log(avctx, AV_LOG_ERROR, "failed to decode channel %d\n", ch);

  1974.             memset(outptr[0], 0, MPA_FRAME_SIZE*sizeof(OUT_INT));

  1975.             if (m->nb_channels > 1)

  1976.                 memset(outptr[1], 0, MPA_FRAME_SIZE*sizeof(OUT_INT));

  1977.             ret = m->nb_channels * MPA_FRAME_SIZE*sizeof(OUT_INT);

  1978.         }

  1979. 

  1980.         out_size += ret;

  1981.         buf      += fsize;

  1982.         len      -= fsize;

  1983. 

  1984.         avctx->bit_rate += m->bit_rate;

  1985.     }

  1986.     if (ch != avctx->channels) {

  1987.         av_log(avctx, AV_LOG_ERROR, "failed to decode all channels\n");

  1988.         return AVERROR_INVALIDDATA;

  1989.     }

  1990. 

  1991.     /* update codec info */

  1992.     avctx->sample_rate = s->mp3decctx[0]->sample_rate;

  1993. 

  1994.     frame->nb_samples = out_size / (avctx->channels * sizeof(OUT_INT));

  1995.     *got_frame_ptr    = 1;

  1996. 

  1997.     return buf_size;

  1998. }

  1999. #endif /* CONFIG_MP3ON4_DECODER || CONFIG_MP3ON4FLOAT_DECODER */