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FFmpeg/libavcodec/mpegaudiodec.c

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  1. /*

  2.  * MPEG Audio decoder

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

  4.  *

  5.  * This library is free software; you can redistribute it and/or

  6.  * modify it under the terms of the GNU Lesser General Public

  7.  * License as published by the Free Software Foundation; either

  8.  * version 2 of the License, or (at your option) any later version.

  9.  *

  10.  * This library is distributed in the hope that it will be useful,

  11.  * but WITHOUT ANY WARRANTY; without even the implied warranty of

  12.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

  13.  * Lesser General Public License for more details.

  14.  *

  15.  * You should have received a copy of the GNU Lesser General Public

  16.  * License along with this library; if not, write to the Free Software

  17.  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

  18.  */

  19. 

  20. /**

  21.  * @file mpegaudiodec.c

  22.  * MPEG Audio decoder.

  23.  */ 

  24. 

  25. //#define DEBUG

  26. #include "avcodec.h"

  27. #include "bitstream.h"

  28. #include "mpegaudio.h"

  29. #include "dsputil.h"

  30. 

  31. /*

  32.  * TODO:

  33.  *  - in low precision mode, use more 16 bit multiplies in synth filter

  34.  *  - test lsf / mpeg25 extensively.

  35.  */

  36. 

  37. /* define USE_HIGHPRECISION to have a bit exact (but slower) mpeg

  38.    audio decoder */

  39. #ifdef CONFIG_MPEGAUDIO_HP

  40. #define USE_HIGHPRECISION

  41. #endif

  42. 

  43. #ifdef USE_HIGHPRECISION

  44. #define FRAC_BITS   23   /* fractional bits for sb_samples and dct */

  45. #define WFRAC_BITS  16   /* fractional bits for window */

  46. #else

  47. #define FRAC_BITS   15   /* fractional bits for sb_samples and dct */

  48. #define WFRAC_BITS  14   /* fractional bits for window */

  49. #endif

  50. 

  51. #define FRAC_ONE    (1 << FRAC_BITS)

  52. 

  53. #define MULL(a,b) (((int64_t)(a) * (int64_t)(b)) >> FRAC_BITS)

  54. #define MUL64(a,b) ((int64_t)(a) * (int64_t)(b))

  55. #define FIX(a)   ((int)((a) * FRAC_ONE))

  56. /* WARNING: only correct for posititive numbers */

  57. #define FIXR(a)   ((int)((a) * FRAC_ONE + 0.5))

  58. #define FRAC_RND(a) (((a) + (FRAC_ONE/2)) >> FRAC_BITS)

  59. 

  60. #if FRAC_BITS <= 15

  61. typedef int16_t MPA_INT;

  62. #else

  63. typedef int32_t MPA_INT;

  64. #endif

  65. 

  66. /****************/

  67. 

  68. #define HEADER_SIZE 4

  69. #define BACKSTEP_SIZE 512

  70. 

  71. struct GranuleDef;

  72. 

  73. typedef struct MPADecodeContext {

  74.     uint8_t inbuf1[2][MPA_MAX_CODED_FRAME_SIZE + BACKSTEP_SIZE];	/* input buffer */

  75.     int inbuf_index;

  76.     uint8_t *inbuf_ptr, *inbuf;

  77.     int frame_size;

  78.     int free_format_frame_size; /* frame size in case of free format

  79.                                    (zero if currently unknown) */

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

  81.     uint32_t free_format_next_header; 

  82.     int error_protection;

  83.     int layer;

  84.     int sample_rate;

  85.     int sample_rate_index; /* between 0 and 8 */

  86.     int bit_rate;

  87.     int old_frame_size;

  88.     GetBitContext gb;

  89.     int nb_channels;

  90.     int mode;

  91.     int mode_ext;

  92.     int lsf;

  93.     MPA_INT synth_buf[MPA_MAX_CHANNELS][512 * 2] __attribute__((aligned(16)));

  94.     int synth_buf_offset[MPA_MAX_CHANNELS];

  95.     int32_t sb_samples[MPA_MAX_CHANNELS][36][SBLIMIT] __attribute__((aligned(16)));

  96.     int32_t mdct_buf[MPA_MAX_CHANNELS][SBLIMIT * 18]; /* previous samples, for layer 3 MDCT */

  97. #ifdef DEBUG

  98.     int frame_count;

  99. #endif

  100.     void (*compute_antialias)(struct MPADecodeContext *s, struct GranuleDef *g);

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

  102.     unsigned int dither_state;

  103. } MPADecodeContext;

  104. 

  105. /* layer 3 "granule" */

  106. typedef struct GranuleDef {

  107.     uint8_t scfsi;

  108.     int part2_3_length;

  109.     int big_values;

  110.     int global_gain;

  111.     int scalefac_compress;

  112.     uint8_t block_type;

  113.     uint8_t switch_point;

  114.     int table_select[3];

  115.     int subblock_gain[3];

  116.     uint8_t scalefac_scale;

  117.     uint8_t count1table_select;

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

  119.     int preflag;

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

  121.     uint8_t scale_factors[40];

  122.     int32_t sb_hybrid[SBLIMIT * 18]; /* 576 samples */

  123. } GranuleDef;

  124. 

  125. #define MODE_EXT_MS_STEREO 2

  126. #define MODE_EXT_I_STEREO  1

  127. 

  128. /* layer 3 huffman tables */

  129. typedef struct HuffTable {

  130.     int xsize;

  131.     const uint8_t *bits;

  132.     const uint16_t *codes;

  133. } HuffTable;

  134. 

  135. #include "mpegaudiodectab.h"

  136. 

  137. static void compute_antialias_integer(MPADecodeContext *s, GranuleDef *g);

  138. static void compute_antialias_float(MPADecodeContext *s, GranuleDef *g);

  139. 

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

  141. static VLC huff_vlc[16]; 

  142. static uint8_t *huff_code_table[16];

  143. static VLC huff_quad_vlc[2];

  144. /* computed from band_size_long */

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

  146. /* XXX: free when all decoders are closed */

  147. #define TABLE_4_3_SIZE (8191 + 16)

  148. static int8_t  *table_4_3_exp;

  149. #if FRAC_BITS <= 15

  150. static uint16_t *table_4_3_value;

  151. #else

  152. static uint32_t *table_4_3_value;

  153. #endif

  154. /* intensity stereo coef table */

  155. static int32_t is_table[2][16];

  156. static int32_t is_table_lsf[2][2][16];

  157. static int32_t csa_table[8][4];

  158. static float csa_table_float[8][4];

  159. static int32_t mdct_win[8][36];

  160. 

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

  162. static uint16_t scale_factor_modshift[64];

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

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

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

  166. 

  167. #define SCALE_GEN(v) \

  168. { FIXR(1.0 * (v)), FIXR(0.7937005259 * (v)), FIXR(0.6299605249 * (v)) }

  169. 

  170. static int32_t scale_factor_mult2[3][3] = {

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

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

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

  174. };

  175. 

  176. /* 2^(n/4) */

  177. static uint32_t scale_factor_mult3[4] = {

  178.     FIXR(1.0),

  179.     FIXR(1.18920711500272106671),

  180.     FIXR(1.41421356237309504880),

  181.     FIXR(1.68179283050742908605),

  182. };

  183. 

  184. void ff_mpa_synth_init(MPA_INT *window);

  185. static MPA_INT window[512] __attribute__((aligned(16)));

  186.     

  187. /* layer 1 unscaling */

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

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

  190. {

  191.     int shift, mod;

  192.     int64_t val;

  193. 

  194.     shift = scale_factor_modshift[scale_factor];

  195.     mod = shift & 3;

  196.     shift >>= 2;

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

  198.     shift += n;

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

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

  201. }

  202. 

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

  204. {

  205.     int shift, mod, val;

  206. 

  207.     shift = scale_factor_modshift[scale_factor];

  208.     mod = shift & 3;

  209.     shift >>= 2;

  210. 

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

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

  213.     if (shift > 0)

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

  215.     return val;

  216. }

  217. 

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

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

  220. {

  221. #if FRAC_BITS <= 15    

  222.     unsigned int m;

  223. #else

  224.     uint64_t m;

  225. #endif

  226.     int e;

  227. 

  228.     e = table_4_3_exp[value];

  229.     e += (exponent >> 2);

  230.     e = FRAC_BITS - e;

  231. #if FRAC_BITS <= 15    

  232.     if (e > 31)

  233.         e = 31;

  234. #endif

  235.     m = table_4_3_value[value];

  236. #if FRAC_BITS <= 15    

  237.     m = (m * scale_factor_mult3[exponent & 3]);

  238.     m = (m + (1 << (e-1))) >> e;

  239.     return m;

  240. #else

  241.     m = MUL64(m, scale_factor_mult3[exponent & 3]);

  242.     m = (m + (uint64_t_C(1) << (e-1))) >> e;

  243.     return m;

  244. #endif

  245. }

  246. 

  247. /* all integer n^(4/3) computation code */

  248. #define DEV_ORDER 13

  249. 

  250. #define POW_FRAC_BITS 24

  251. #define POW_FRAC_ONE    (1 << POW_FRAC_BITS)

  252. #define POW_FIX(a)   ((int)((a) * POW_FRAC_ONE))

  253. #define POW_MULL(a,b) (((int64_t)(a) * (int64_t)(b)) >> POW_FRAC_BITS)

  254. 

  255. static int dev_4_3_coefs[DEV_ORDER];

  256. 

  257. static int pow_mult3[3] = {

  258.     POW_FIX(1.0),

  259.     POW_FIX(1.25992104989487316476),

  260.     POW_FIX(1.58740105196819947474),

  261. };

  262. 

  263. static void int_pow_init(void)

  264. {

  265.     int i, a;

  266. 

  267.     a = POW_FIX(1.0);

  268.     for(i=0;i<DEV_ORDER;i++) {

  269.         a = POW_MULL(a, POW_FIX(4.0 / 3.0) - i * POW_FIX(1.0)) / (i + 1);

  270.         dev_4_3_coefs[i] = a;

  271.     }

  272. }

  273. 

  274. /* return the mantissa and the binary exponent */

  275. static int int_pow(int i, int *exp_ptr)

  276. {

  277.     int e, er, eq, j;

  278.     int a, a1;

  279.     

  280.     /* renormalize */

  281.     a = i;

  282.     e = POW_FRAC_BITS;

  283.     while (a < (1 << (POW_FRAC_BITS - 1))) {

  284.         a = a << 1;

  285.         e--;

  286.     }

  287.     a -= (1 << POW_FRAC_BITS);

  288.     a1 = 0;

  289.     for(j = DEV_ORDER - 1; j >= 0; j--)

  290.         a1 = POW_MULL(a, dev_4_3_coefs[j] + a1);

  291.     a = (1 << POW_FRAC_BITS) + a1;

  292.     /* exponent compute (exact) */

  293.     e = e * 4;

  294.     er = e % 3;

  295.     eq = e / 3;

  296.     a = POW_MULL(a, pow_mult3[er]);

  297.     while (a >= 2 * POW_FRAC_ONE) {

  298.         a = a >> 1;

  299.         eq++;

  300.     }

  301.     /* convert to float */

  302.     while (a < POW_FRAC_ONE) {

  303.         a = a << 1;

  304.         eq--;

  305.     }

  306.     /* now POW_FRAC_ONE <= a < 2 * POW_FRAC_ONE */

  307. #if POW_FRAC_BITS > FRAC_BITS

  308.     a = (a + (1 << (POW_FRAC_BITS - FRAC_BITS - 1))) >> (POW_FRAC_BITS - FRAC_BITS);

  309.     /* correct overflow */

  310.     if (a >= 2 * (1 << FRAC_BITS)) {

  311.         a = a >> 1;

  312.         eq++;

  313.     }

  314. #endif

  315.     *exp_ptr = eq;

  316.     return a;

  317. }

  318. 

  319. static int decode_init(AVCodecContext * avctx)

  320. {

  321.     MPADecodeContext *s = avctx->priv_data;

  322.     static int init=0;

  323.     int i, j, k;

  324. 

  325.     if(avctx->antialias_algo == FF_AA_INT)

  326.         s->compute_antialias= compute_antialias_integer;

  327.     else

  328.         s->compute_antialias= compute_antialias_float;

  329. 

  330.     if (!init && !avctx->parse_only) {

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

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

  333.             int shift, mod;

  334.             /* 1.0 (i = 3) is normalized to 2 ^ FRAC_BITS */

  335.             shift = (i / 3);

  336.             mod = i % 3;

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

  338.         }

  339. 

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

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

  342.             int n, norm;

  343.             n = i + 2;

  344.             norm = ((int64_t_C(1) << n) * FRAC_ONE) / ((1 << n) - 1);

  345.             scale_factor_mult[i][0] = MULL(FIXR(1.0 * 2.0), norm);

  346.             scale_factor_mult[i][1] = MULL(FIXR(0.7937005259 * 2.0), norm);

  347.             scale_factor_mult[i][2] = MULL(FIXR(0.6299605249 * 2.0), norm);

  348.             dprintf("%d: norm=%x s=%x %x %x\n",

  349.                     i, norm, 

  350.                     scale_factor_mult[i][0],

  351.                     scale_factor_mult[i][1],

  352.                     scale_factor_mult[i][2]);

  353.         }

  354.         

  355. 	ff_mpa_synth_init(window);

  356.         

  357.         /* huffman decode tables */

  358.         huff_code_table[0] = NULL;

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

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

  361. 	    int xsize, x, y;

  362.             unsigned int n;

  363.             uint8_t *code_table;

  364. 

  365.             xsize = h->xsize;

  366.             n = xsize * xsize;

  367.             /* XXX: fail test */

  368.             init_vlc(&huff_vlc[i], 8, n, 

  369.                      h->bits, 1, 1, h->codes, 2, 2, 1);

  370.             

  371.             code_table = av_mallocz(n);

  372.             j = 0;

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

  374.                 for(y=0;y<xsize;y++)

  375.                     code_table[j++] = (x << 4) | y;

  376.             }

  377.             huff_code_table[i] = code_table;

  378.         }

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

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

  381.                      mpa_quad_bits[i], 1, 1, mpa_quad_codes[i], 1, 1, 1);

  382.         }

  383. 

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

  385.             k = 0;

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

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

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

  389.             }

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

  391.         }

  392. 

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

  394. 	table_4_3_exp= av_mallocz_static(TABLE_4_3_SIZE * sizeof(table_4_3_exp[0]));

  395.         if(!table_4_3_exp)

  396. 	    return -1;

  397. 	table_4_3_value= av_mallocz_static(TABLE_4_3_SIZE * sizeof(table_4_3_value[0]));

  398.         if(!table_4_3_value)

  399.             return -1;

  400.         

  401.         int_pow_init();

  402.         for(i=1;i<TABLE_4_3_SIZE;i++) {

  403.             int e, m;

  404.             m = int_pow(i, &e);

  405. #if 0

  406.             /* test code */

  407.             {

  408.                 double f, fm;

  409.                 int e1, m1;

  410.                 f = pow((double)i, 4.0 / 3.0);

  411.                 fm = frexp(f, &e1);

  412.                 m1 = FIXR(2 * fm);

  413. #if FRAC_BITS <= 15

  414.                 if ((unsigned short)m1 != m1) {

  415.                     m1 = m1 >> 1;

  416.                     e1++;

  417.                 }

  418. #endif

  419.                 e1--;

  420.                 if (m != m1 || e != e1) {

  421.                     printf("%4d: m=%x m1=%x e=%d e1=%d\n",

  422.                            i, m, m1, e, e1);

  423.                 }

  424.             }

  425. #endif

  426.             /* normalized to FRAC_BITS */

  427.             table_4_3_value[i] = m;

  428.             table_4_3_exp[i] = e;

  429.         }

  430.         

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

  432.             float f;

  433.             int v;

  434.             if (i != 6) {

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

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

  437.             } else {

  438.                 v = FIXR(1.0);

  439.             }

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

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

  442.         }

  443.         /* invalid values */

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

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

  446. 

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

  448.             double f;

  449.             int e, k;

  450. 

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

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

  453.                 f = pow(2.0, e / 4.0);

  454.                 k = i & 1;

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

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

  457.                 dprintf("is_table_lsf %d %d: %x %x\n", 

  458.                         i, j, is_table_lsf[j][0][i], is_table_lsf[j][1][i]);

  459.             }

  460.         }

  461. 

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

  463.             float ci, cs, ca;

  464.             ci = ci_table[i];

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

  466.             ca = cs * ci;

  467.             csa_table[i][0] = FIX(cs);

  468.             csa_table[i][1] = FIX(ca);

  469.             csa_table[i][2] = FIX(ca) + FIX(cs);

  470.             csa_table[i][3] = FIX(ca) - FIX(cs); 

  471.             csa_table_float[i][0] = cs;

  472.             csa_table_float[i][1] = ca;

  473.             csa_table_float[i][2] = ca + cs;

  474.             csa_table_float[i][3] = ca - cs; 

  475. //            printf("%d %d %d %d\n", FIX(cs), FIX(cs-1), FIX(ca), FIX(cs)-FIX(ca));

  476.         }

  477. 

  478.         /* compute mdct windows */

  479.         for(i=0;i<36;i++) {

  480.             int v;

  481.             v = FIXR(sin(M_PI * (i + 0.5) / 36.0));

  482.             mdct_win[0][i] = v;

  483.             mdct_win[1][i] = v;

  484.             mdct_win[3][i] = v;

  485.         }

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

  487.             mdct_win[1][18 + i] = FIXR(1.0);

  488.             mdct_win[1][24 + i] = FIXR(sin(M_PI * ((i + 6) + 0.5) / 12.0));

  489.             mdct_win[1][30 + i] = FIXR(0.0);

  490. 

  491.             mdct_win[3][i] = FIXR(0.0);

  492.             mdct_win[3][6 + i] = FIXR(sin(M_PI * (i + 0.5) / 12.0));

  493.             mdct_win[3][12 + i] = FIXR(1.0);

  494.         }

  495. 

  496.         for(i=0;i<12;i++)

  497.             mdct_win[2][i] = FIXR(sin(M_PI * (i + 0.5) / 12.0));

  498.         

  499.         /* NOTE: we do frequency inversion adter the MDCT by changing

  500.            the sign of the right window coefs */

  501.         for(j=0;j<4;j++) {

  502.             for(i=0;i<36;i+=2) {

  503.                 mdct_win[j + 4][i] = mdct_win[j][i];

  504.                 mdct_win[j + 4][i + 1] = -mdct_win[j][i + 1];

  505.             }

  506.         }

  507. 

  508. #if defined(DEBUG)

  509.         for(j=0;j<8;j++) {

  510.             printf("win%d=\n", j);

  511.             for(i=0;i<36;i++)

  512.                 printf("%f, ", (double)mdct_win[j][i] / FRAC_ONE);

  513.             printf("\n");

  514.         }

  515. #endif

  516.         init = 1;

  517.     }

  518. 

  519.     s->inbuf_index = 0;

  520.     s->inbuf = &s->inbuf1[s->inbuf_index][BACKSTEP_SIZE];

  521.     s->inbuf_ptr = s->inbuf;

  522. #ifdef DEBUG

  523.     s->frame_count = 0;

  524. #endif

  525.     if (avctx->codec_id == CODEC_ID_MP3ADU)

  526.         s->adu_mode = 1;

  527.     return 0;

  528. }

  529. 

  530. /* tab[i][j] = 1.0 / (2.0 * cos(pi*(2*k+1) / 2^(6 - j))) */

  531. 

  532. /* cos(i*pi/64) */

  533. 

  534. #define COS0_0  FIXR(0.50060299823519630134)

  535. #define COS0_1  FIXR(0.50547095989754365998)

  536. #define COS0_2  FIXR(0.51544730992262454697)

  537. #define COS0_3  FIXR(0.53104259108978417447)

  538. #define COS0_4  FIXR(0.55310389603444452782)

  539. #define COS0_5  FIXR(0.58293496820613387367)

  540. #define COS0_6  FIXR(0.62250412303566481615)

  541. #define COS0_7  FIXR(0.67480834145500574602)

  542. #define COS0_8  FIXR(0.74453627100229844977)

  543. #define COS0_9  FIXR(0.83934964541552703873)

  544. #define COS0_10 FIXR(0.97256823786196069369)

  545. #define COS0_11 FIXR(1.16943993343288495515)

  546. #define COS0_12 FIXR(1.48416461631416627724)

  547. #define COS0_13 FIXR(2.05778100995341155085)

  548. #define COS0_14 FIXR(3.40760841846871878570)

  549. #define COS0_15 FIXR(10.19000812354805681150)

  550. 

  551. #define COS1_0 FIXR(0.50241928618815570551)

  552. #define COS1_1 FIXR(0.52249861493968888062)

  553. #define COS1_2 FIXR(0.56694403481635770368)

  554. #define COS1_3 FIXR(0.64682178335999012954)

  555. #define COS1_4 FIXR(0.78815462345125022473)

  556. #define COS1_5 FIXR(1.06067768599034747134)

  557. #define COS1_6 FIXR(1.72244709823833392782)

  558. #define COS1_7 FIXR(5.10114861868916385802)

  559. 

  560. #define COS2_0 FIXR(0.50979557910415916894)

  561. #define COS2_1 FIXR(0.60134488693504528054)

  562. #define COS2_2 FIXR(0.89997622313641570463)

  563. #define COS2_3 FIXR(2.56291544774150617881)

  564. 

  565. #define COS3_0 FIXR(0.54119610014619698439)

  566. #define COS3_1 FIXR(1.30656296487637652785)

  567. 

  568. #define COS4_0 FIXR(0.70710678118654752439)

  569. 

  570. /* butterfly operator */

  571. #define BF(a, b, c)\

  572. {\

  573.     tmp0 = tab[a] + tab[b];\

  574.     tmp1 = tab[a] - tab[b];\

  575.     tab[a] = tmp0;\

  576.     tab[b] = MULL(tmp1, c);\

  577. }

  578. 

  579. #define BF1(a, b, c, d)\

  580. {\

  581.     BF(a, b, COS4_0);\

  582.     BF(c, d, -COS4_0);\

  583.     tab[c] += tab[d];\

  584. }

  585. 

  586. #define BF2(a, b, c, d)\

  587. {\

  588.     BF(a, b, COS4_0);\

  589.     BF(c, d, -COS4_0);\

  590.     tab[c] += tab[d];\

  591.     tab[a] += tab[c];\

  592.     tab[c] += tab[b];\

  593.     tab[b] += tab[d];\

  594. }

  595. 

  596. #define ADD(a, b) tab[a] += tab[b]

  597. 

  598. /* DCT32 without 1/sqrt(2) coef zero scaling. */

  599. static void dct32(int32_t *out, int32_t *tab)

  600. {

  601.     int tmp0, tmp1;

  602. 

  603.     /* pass 1 */

  604.     BF(0, 31, COS0_0);

  605.     BF(1, 30, COS0_1);

  606.     BF(2, 29, COS0_2);

  607.     BF(3, 28, COS0_3);

  608.     BF(4, 27, COS0_4);

  609.     BF(5, 26, COS0_5);

  610.     BF(6, 25, COS0_6);

  611.     BF(7, 24, COS0_7);

  612.     BF(8, 23, COS0_8);

  613.     BF(9, 22, COS0_9);

  614.     BF(10, 21, COS0_10);

  615.     BF(11, 20, COS0_11);

  616.     BF(12, 19, COS0_12);

  617.     BF(13, 18, COS0_13);

  618.     BF(14, 17, COS0_14);

  619.     BF(15, 16, COS0_15);

  620. 

  621.     /* pass 2 */

  622.     BF(0, 15, COS1_0);

  623.     BF(1, 14, COS1_1);

  624.     BF(2, 13, COS1_2);

  625.     BF(3, 12, COS1_3);

  626.     BF(4, 11, COS1_4);

  627.     BF(5, 10, COS1_5);

  628.     BF(6,  9, COS1_6);

  629.     BF(7,  8, COS1_7);

  630.     

  631.     BF(16, 31, -COS1_0);

  632.     BF(17, 30, -COS1_1);

  633.     BF(18, 29, -COS1_2);

  634.     BF(19, 28, -COS1_3);

  635.     BF(20, 27, -COS1_4);

  636.     BF(21, 26, -COS1_5);

  637.     BF(22, 25, -COS1_6);

  638.     BF(23, 24, -COS1_7);

  639.     

  640.     /* pass 3 */

  641.     BF(0, 7, COS2_0);

  642.     BF(1, 6, COS2_1);

  643.     BF(2, 5, COS2_2);

  644.     BF(3, 4, COS2_3);

  645.     

  646.     BF(8, 15, -COS2_0);

  647.     BF(9, 14, -COS2_1);

  648.     BF(10, 13, -COS2_2);

  649.     BF(11, 12, -COS2_3);

  650.     

  651.     BF(16, 23, COS2_0);

  652.     BF(17, 22, COS2_1);

  653.     BF(18, 21, COS2_2);

  654.     BF(19, 20, COS2_3);

  655.     

  656.     BF(24, 31, -COS2_0);

  657.     BF(25, 30, -COS2_1);

  658.     BF(26, 29, -COS2_2);

  659.     BF(27, 28, -COS2_3);

  660. 

  661.     /* pass 4 */

  662.     BF(0, 3, COS3_0);

  663.     BF(1, 2, COS3_1);

  664.     

  665.     BF(4, 7, -COS3_0);

  666.     BF(5, 6, -COS3_1);

  667.     

  668.     BF(8, 11, COS3_0);

  669.     BF(9, 10, COS3_1);

  670.     

  671.     BF(12, 15, -COS3_0);

  672.     BF(13, 14, -COS3_1);

  673.     

  674.     BF(16, 19, COS3_0);

  675.     BF(17, 18, COS3_1);

  676.     

  677.     BF(20, 23, -COS3_0);

  678.     BF(21, 22, -COS3_1);

  679.     

  680.     BF(24, 27, COS3_0);

  681.     BF(25, 26, COS3_1);

  682.     

  683.     BF(28, 31, -COS3_0);

  684.     BF(29, 30, -COS3_1);

  685.     

  686.     /* pass 5 */

  687.     BF1(0, 1, 2, 3);

  688.     BF2(4, 5, 6, 7);

  689.     BF1(8, 9, 10, 11);

  690.     BF2(12, 13, 14, 15);

  691.     BF1(16, 17, 18, 19);

  692.     BF2(20, 21, 22, 23);

  693.     BF1(24, 25, 26, 27);

  694.     BF2(28, 29, 30, 31);

  695.     

  696.     /* pass 6 */

  697.     

  698.     ADD( 8, 12);

  699.     ADD(12, 10);

  700.     ADD(10, 14);

  701.     ADD(14,  9);

  702.     ADD( 9, 13);

  703.     ADD(13, 11);

  704.     ADD(11, 15);

  705. 

  706.     out[ 0] = tab[0];

  707.     out[16] = tab[1];

  708.     out[ 8] = tab[2];

  709.     out[24] = tab[3];

  710.     out[ 4] = tab[4];

  711.     out[20] = tab[5];

  712.     out[12] = tab[6];

  713.     out[28] = tab[7];

  714.     out[ 2] = tab[8];

  715.     out[18] = tab[9];

  716.     out[10] = tab[10];

  717.     out[26] = tab[11];

  718.     out[ 6] = tab[12];

  719.     out[22] = tab[13];

  720.     out[14] = tab[14];

  721.     out[30] = tab[15];

  722.     

  723.     ADD(24, 28);

  724.     ADD(28, 26);

  725.     ADD(26, 30);

  726.     ADD(30, 25);

  727.     ADD(25, 29);

  728.     ADD(29, 27);

  729.     ADD(27, 31);

  730. 

  731.     out[ 1] = tab[16] + tab[24];

  732.     out[17] = tab[17] + tab[25];

  733.     out[ 9] = tab[18] + tab[26];

  734.     out[25] = tab[19] + tab[27];

  735.     out[ 5] = tab[20] + tab[28];

  736.     out[21] = tab[21] + tab[29];

  737.     out[13] = tab[22] + tab[30];

  738.     out[29] = tab[23] + tab[31];

  739.     out[ 3] = tab[24] + tab[20];

  740.     out[19] = tab[25] + tab[21];

  741.     out[11] = tab[26] + tab[22];

  742.     out[27] = tab[27] + tab[23];

  743.     out[ 7] = tab[28] + tab[18];

  744.     out[23] = tab[29] + tab[19];

  745.     out[15] = tab[30] + tab[17];

  746.     out[31] = tab[31];

  747. }

  748. 

  749. #define OUT_SHIFT (WFRAC_BITS + FRAC_BITS - 15)

  750. 

  751. #if FRAC_BITS <= 15

  752. 

  753. static inline int round_sample(int *sum)

  754. {

  755.     int sum1;

  756.     sum1 = (*sum) >> OUT_SHIFT;

  757.     *sum &= (1<<OUT_SHIFT)-1;

  758.     if (sum1 < -32768)

  759.         sum1 = -32768;

  760.     else if (sum1 > 32767)

  761.         sum1 = 32767;

  762.     return sum1;

  763. }

  764. 

  765. #if defined(ARCH_POWERPC_405)

  766. 

  767. /* signed 16x16 -> 32 multiply add accumulate */

  768. #define MACS(rt, ra, rb) \

  769.     asm ("maclhw %0, %2, %3" : "=r" (rt) : "0" (rt), "r" (ra), "r" (rb));

  770. 

  771. /* signed 16x16 -> 32 multiply */

  772. #define MULS(ra, rb) \

  773.     ({ int __rt; asm ("mullhw %0, %1, %2" : "=r" (__rt) : "r" (ra), "r" (rb)); __rt; })

  774. 

  775. #else

  776. 

  777. /* signed 16x16 -> 32 multiply add accumulate */

  778. #define MACS(rt, ra, rb) rt += (ra) * (rb)

  779. 

  780. /* signed 16x16 -> 32 multiply */

  781. #define MULS(ra, rb) ((ra) * (rb))

  782. 

  783. #endif

  784. 

  785. #else

  786. 

  787. static inline int round_sample(int64_t *sum) 

  788. {

  789.     int sum1;

  790.     sum1 = (int)((*sum) >> OUT_SHIFT);

  791.     *sum &= (1<<OUT_SHIFT)-1;

  792.     if (sum1 < -32768)

  793.         sum1 = -32768;

  794.     else if (sum1 > 32767)

  795.         sum1 = 32767;

  796.     return sum1;

  797. }

  798. 

  799. #define MULS(ra, rb) MUL64(ra, rb)

  800. 

  801. #endif

  802. 

  803. #define SUM8(sum, op, w, p) \

  804. {                                               \

  805.     sum op MULS((w)[0 * 64], p[0 * 64]);\

  806.     sum op MULS((w)[1 * 64], p[1 * 64]);\

  807.     sum op MULS((w)[2 * 64], p[2 * 64]);\

  808.     sum op MULS((w)[3 * 64], p[3 * 64]);\

  809.     sum op MULS((w)[4 * 64], p[4 * 64]);\

  810.     sum op MULS((w)[5 * 64], p[5 * 64]);\

  811.     sum op MULS((w)[6 * 64], p[6 * 64]);\

  812.     sum op MULS((w)[7 * 64], p[7 * 64]);\

  813. }

  814. 

  815. #define SUM8P2(sum1, op1, sum2, op2, w1, w2, p) \

  816. {                                               \

  817.     int tmp;\

  818.     tmp = p[0 * 64];\

  819.     sum1 op1 MULS((w1)[0 * 64], tmp);\

  820.     sum2 op2 MULS((w2)[0 * 64], tmp);\

  821.     tmp = p[1 * 64];\

  822.     sum1 op1 MULS((w1)[1 * 64], tmp);\

  823.     sum2 op2 MULS((w2)[1 * 64], tmp);\

  824.     tmp = p[2 * 64];\

  825.     sum1 op1 MULS((w1)[2 * 64], tmp);\

  826.     sum2 op2 MULS((w2)[2 * 64], tmp);\

  827.     tmp = p[3 * 64];\

  828.     sum1 op1 MULS((w1)[3 * 64], tmp);\

  829.     sum2 op2 MULS((w2)[3 * 64], tmp);\

  830.     tmp = p[4 * 64];\

  831.     sum1 op1 MULS((w1)[4 * 64], tmp);\

  832.     sum2 op2 MULS((w2)[4 * 64], tmp);\

  833.     tmp = p[5 * 64];\

  834.     sum1 op1 MULS((w1)[5 * 64], tmp);\

  835.     sum2 op2 MULS((w2)[5 * 64], tmp);\

  836.     tmp = p[6 * 64];\

  837.     sum1 op1 MULS((w1)[6 * 64], tmp);\

  838.     sum2 op2 MULS((w2)[6 * 64], tmp);\

  839.     tmp = p[7 * 64];\

  840.     sum1 op1 MULS((w1)[7 * 64], tmp);\

  841.     sum2 op2 MULS((w2)[7 * 64], tmp);\

  842. }

  843. 

  844. void ff_mpa_synth_init(MPA_INT *window)

  845. {

  846.     int i;

  847. 

  848.     /* max = 18760, max sum over all 16 coefs : 44736 */

  849.     for(i=0;i<257;i++) {

  850.         int v;

  851.         v = mpa_enwindow[i];

  852. #if WFRAC_BITS < 16

  853.         v = (v + (1 << (16 - WFRAC_BITS - 1))) >> (16 - WFRAC_BITS);

  854. #endif

  855.         window[i] = v;

  856.         if ((i & 63) != 0)

  857.             v = -v;

  858.         if (i != 0)

  859.             window[512 - i] = v;

  860.     }	

  861. }

  862. 

  863. /* 32 sub band synthesis filter. Input: 32 sub band samples, Output:

  864.    32 samples. */

  865. /* XXX: optimize by avoiding ring buffer usage */

  866. void ff_mpa_synth_filter(MPA_INT *synth_buf_ptr, int *synth_buf_offset,

  867. 			 MPA_INT *window, int *dither_state,

  868.                          int16_t *samples, int incr, 

  869.                          int32_t sb_samples[SBLIMIT])

  870. {

  871.     int32_t tmp[32];

  872.     register MPA_INT *synth_buf;

  873.     register const MPA_INT *w, *w2, *p;

  874.     int j, offset, v;

  875.     int16_t *samples2;

  876. #if FRAC_BITS <= 15

  877.     int sum, sum2;

  878. #else

  879.     int64_t sum, sum2;

  880. #endif

  881. 

  882.     dct32(tmp, sb_samples);

  883.     

  884.     offset = *synth_buf_offset;

  885.     synth_buf = synth_buf_ptr + offset;

  886. 

  887.     for(j=0;j<32;j++) {

  888.         v = tmp[j];

  889. #if FRAC_BITS <= 15

  890.         /* NOTE: can cause a loss in precision if very high amplitude

  891.            sound */

  892.         if (v > 32767)

  893.             v = 32767;

  894.         else if (v < -32768)

  895.             v = -32768;

  896. #endif

  897.         synth_buf[j] = v;

  898.     }

  899.     /* copy to avoid wrap */

  900.     memcpy(synth_buf + 512, synth_buf, 32 * sizeof(MPA_INT));

  901. 

  902.     samples2 = samples + 31 * incr;

  903.     w = window;

  904.     w2 = window + 31;

  905. 

  906.     sum = *dither_state;

  907.     p = synth_buf + 16;

  908.     SUM8(sum, +=, w, p);

  909.     p = synth_buf + 48;

  910.     SUM8(sum, -=, w + 32, p);

  911.     *samples = round_sample(&sum);

  912.     samples += incr;

  913.     w++;

  914. 

  915.     /* we calculate two samples at the same time to avoid one memory

  916.        access per two sample */

  917.     for(j=1;j<16;j++) {

  918.         sum2 = 0;

  919.         p = synth_buf + 16 + j;

  920.         SUM8P2(sum, +=, sum2, -=, w, w2, p);

  921.         p = synth_buf + 48 - j;

  922.         SUM8P2(sum, -=, sum2, -=, w + 32, w2 + 32, p);

  923. 

  924.         *samples = round_sample(&sum);

  925.         samples += incr;

  926.         sum += sum2;

  927.         *samples2 = round_sample(&sum);

  928.         samples2 -= incr;

  929.         w++;

  930.         w2--;

  931.     }

  932.     

  933.     p = synth_buf + 32;

  934.     SUM8(sum, -=, w + 32, p);

  935.     *samples = round_sample(&sum);

  936.     *dither_state= sum;

  937. 

  938.     offset = (offset - 32) & 511;

  939.     *synth_buf_offset = offset;

  940. }

  941. 

  942. /* cos(pi*i/24) */

  943. #define C1  FIXR(0.99144486137381041114)

  944. #define C3  FIXR(0.92387953251128675612)

  945. #define C5  FIXR(0.79335334029123516458)

  946. #define C7  FIXR(0.60876142900872063941)

  947. #define C9  FIXR(0.38268343236508977173)

  948. #define C11 FIXR(0.13052619222005159154)

  949. 

  950. /* 12 points IMDCT. We compute it "by hand" by factorizing obvious

  951.    cases. */

  952. static void imdct12(int *out, int *in)

  953. {

  954.     int tmp;

  955.     int64_t in1_3, in1_9, in4_3, in4_9;

  956. 

  957.     in1_3 = MUL64(in[1], C3);

  958.     in1_9 = MUL64(in[1], C9);

  959.     in4_3 = MUL64(in[4], C3);

  960.     in4_9 = MUL64(in[4], C9);

  961.     

  962.     tmp = FRAC_RND(MUL64(in[0], C7) - in1_3 - MUL64(in[2], C11) + 

  963.                    MUL64(in[3], C1) - in4_9 - MUL64(in[5], C5));

  964.     out[0] = tmp;

  965.     out[5] = -tmp;

  966.     tmp = FRAC_RND(MUL64(in[0] - in[3], C9) - in1_3 + 

  967.                    MUL64(in[2] + in[5], C3) - in4_9);

  968.     out[1] = tmp;

  969.     out[4] = -tmp;

  970.     tmp = FRAC_RND(MUL64(in[0], C11) - in1_9 + MUL64(in[2], C7) -

  971.                    MUL64(in[3], C5) + in4_3 - MUL64(in[5], C1));

  972.     out[2] = tmp;

  973.     out[3] = -tmp;

  974.     tmp = FRAC_RND(MUL64(-in[0], C5) + in1_9 + MUL64(in[2], C1) + 

  975.                    MUL64(in[3], C11) - in4_3 - MUL64(in[5], C7));

  976.     out[6] = tmp;

  977.     out[11] = tmp;

  978.     tmp = FRAC_RND(MUL64(-in[0] + in[3], C3) - in1_9 + 

  979.                    MUL64(in[2] + in[5], C9) + in4_3);

  980.     out[7] = tmp;

  981.     out[10] = tmp;

  982.     tmp = FRAC_RND(-MUL64(in[0], C1) - in1_3 - MUL64(in[2], C5) -

  983.                    MUL64(in[3], C7) - in4_9 - MUL64(in[5], C11));

  984.     out[8] = tmp;

  985.     out[9] = tmp;

  986. }

  987. 

  988. #undef C1

  989. #undef C3

  990. #undef C5

  991. #undef C7

  992. #undef C9

  993. #undef C11

  994. 

  995. /* cos(pi*i/18) */

  996. #define C1 FIXR(0.98480775301220805936)

  997. #define C2 FIXR(0.93969262078590838405)

  998. #define C3 FIXR(0.86602540378443864676)

  999. #define C4 FIXR(0.76604444311897803520)

  1000. #define C5 FIXR(0.64278760968653932632)

  1001. #define C6 FIXR(0.5)

  1002. #define C7 FIXR(0.34202014332566873304)

  1003. #define C8 FIXR(0.17364817766693034885)

  1004. 

  1005. /* 0.5 / cos(pi*(2*i+1)/36) */

  1006. static const int icos36[9] = {

  1007.     FIXR(0.50190991877167369479),

  1008.     FIXR(0.51763809020504152469),

  1009.     FIXR(0.55168895948124587824),

  1010.     FIXR(0.61038729438072803416),

  1011.     FIXR(0.70710678118654752439),

  1012.     FIXR(0.87172339781054900991),

  1013.     FIXR(1.18310079157624925896),

  1014.     FIXR(1.93185165257813657349),

  1015.     FIXR(5.73685662283492756461),

  1016. };

  1017. 

  1018. static const int icos72[18] = {

  1019.     /* 0.5 / cos(pi*(2*i+19)/72) */

  1020.     FIXR(0.74009361646113053152),

  1021.     FIXR(0.82133981585229078570),

  1022.     FIXR(0.93057949835178895673),

  1023.     FIXR(1.08284028510010010928),

  1024.     FIXR(1.30656296487637652785),

  1025.     FIXR(1.66275476171152078719),

  1026.     FIXR(2.31011315767264929558),

  1027.     FIXR(3.83064878777019433457),

  1028.     FIXR(11.46279281302667383546),

  1029. 

  1030.     /* 0.5 / cos(pi*(2*(i + 18) +19)/72) */

  1031.     FIXR(-0.67817085245462840086),

  1032.     FIXR(-0.63023620700513223342),

  1033.     FIXR(-0.59284452371708034528),

  1034.     FIXR(-0.56369097343317117734),

  1035.     FIXR(-0.54119610014619698439),

  1036.     FIXR(-0.52426456257040533932),

  1037.     FIXR(-0.51213975715725461845),

  1038.     FIXR(-0.50431448029007636036),

  1039.     FIXR(-0.50047634258165998492),

  1040. };

  1041. 

  1042. /* using Lee like decomposition followed by hand coded 9 points DCT */

  1043. static void imdct36(int *out, int *in)

  1044. {

  1045.     int i, j, t0, t1, t2, t3, s0, s1, s2, s3;

  1046.     int tmp[18], *tmp1, *in1;

  1047.     int64_t in3_3, in6_6;

  1048. 

  1049.     for(i=17;i>=1;i--)

  1050.         in[i] += in[i-1];

  1051.     for(i=17;i>=3;i-=2)

  1052.         in[i] += in[i-2];

  1053. 

  1054.     for(j=0;j<2;j++) {

  1055.         tmp1 = tmp + j;

  1056.         in1 = in + j;

  1057. 

  1058.         in3_3 = MUL64(in1[2*3], C3);

  1059.         in6_6 = MUL64(in1[2*6], C6);

  1060. 

  1061.         tmp1[0] = FRAC_RND(MUL64(in1[2*1], C1) + in3_3 + 

  1062.                            MUL64(in1[2*5], C5) + MUL64(in1[2*7], C7));

  1063.         tmp1[2] = in1[2*0] + FRAC_RND(MUL64(in1[2*2], C2) + 

  1064.                                       MUL64(in1[2*4], C4) + in6_6 + 

  1065.                                       MUL64(in1[2*8], C8));

  1066.         tmp1[4] = FRAC_RND(MUL64(in1[2*1] - in1[2*5] - in1[2*7], C3));

  1067.         tmp1[6] = FRAC_RND(MUL64(in1[2*2] - in1[2*4] - in1[2*8], C6)) - 

  1068.             in1[2*6] + in1[2*0];

  1069.         tmp1[8] = FRAC_RND(MUL64(in1[2*1], C5) - in3_3 - 

  1070.                            MUL64(in1[2*5], C7) + MUL64(in1[2*7], C1));

  1071.         tmp1[10] = in1[2*0] + FRAC_RND(MUL64(-in1[2*2], C8) - 

  1072.                                        MUL64(in1[2*4], C2) + in6_6 + 

  1073.                                        MUL64(in1[2*8], C4));

  1074.         tmp1[12] = FRAC_RND(MUL64(in1[2*1], C7) - in3_3 + 

  1075.                             MUL64(in1[2*5], C1) - 

  1076.                             MUL64(in1[2*7], C5));

  1077.         tmp1[14] = in1[2*0] + FRAC_RND(MUL64(-in1[2*2], C4) + 

  1078.                                        MUL64(in1[2*4], C8) + in6_6 - 

  1079.                                        MUL64(in1[2*8], C2));

  1080.         tmp1[16] = in1[2*0] - in1[2*2] + in1[2*4] - in1[2*6] + in1[2*8];

  1081.     }

  1082. 

  1083.     i = 0;

  1084.     for(j=0;j<4;j++) {

  1085.         t0 = tmp[i];

  1086.         t1 = tmp[i + 2];

  1087.         s0 = t1 + t0;

  1088.         s2 = t1 - t0;

  1089. 

  1090.         t2 = tmp[i + 1];

  1091.         t3 = tmp[i + 3];

  1092.         s1 = MULL(t3 + t2, icos36[j]);

  1093.         s3 = MULL(t3 - t2, icos36[8 - j]);

  1094.         

  1095.         t0 = MULL(s0 + s1, icos72[9 + 8 - j]);

  1096.         t1 = MULL(s0 - s1, icos72[8 - j]);

  1097.         out[18 + 9 + j] = t0;

  1098.         out[18 + 8 - j] = t0;

  1099.         out[9 + j] = -t1;

  1100.         out[8 - j] = t1;

  1101.         

  1102.         t0 = MULL(s2 + s3, icos72[9+j]);

  1103.         t1 = MULL(s2 - s3, icos72[j]);

  1104.         out[18 + 9 + (8 - j)] = t0;

  1105.         out[18 + j] = t0;

  1106.         out[9 + (8 - j)] = -t1;

  1107.         out[j] = t1;

  1108.         i += 4;

  1109.     }

  1110. 

  1111.     s0 = tmp[16];

  1112.     s1 = MULL(tmp[17], icos36[4]);

  1113.     t0 = MULL(s0 + s1, icos72[9 + 4]);

  1114.     t1 = MULL(s0 - s1, icos72[4]);

  1115.     out[18 + 9 + 4] = t0;

  1116.     out[18 + 8 - 4] = t0;

  1117.     out[9 + 4] = -t1;

  1118.     out[8 - 4] = t1;

  1119. }

  1120. 

  1121. /* header decoding. MUST check the header before because no

  1122.    consistency check is done there. Return 1 if free format found and

  1123.    that the frame size must be computed externally */

  1124. static int decode_header(MPADecodeContext *s, uint32_t header)

  1125. {

  1126.     int sample_rate, frame_size, mpeg25, padding;

  1127.     int sample_rate_index, bitrate_index;

  1128.     if (header & (1<<20)) {

  1129.         s->lsf = (header & (1<<19)) ? 0 : 1;

  1130.         mpeg25 = 0;

  1131.     } else {

  1132.         s->lsf = 1;

  1133.         mpeg25 = 1;

  1134.     }

  1135.     

  1136.     s->layer = 4 - ((header >> 17) & 3);

  1137.     /* extract frequency */

  1138.     sample_rate_index = (header >> 10) & 3;

  1139.     sample_rate = mpa_freq_tab[sample_rate_index] >> (s->lsf + mpeg25);

  1140.     sample_rate_index += 3 * (s->lsf + mpeg25);

  1141.     s->sample_rate_index = sample_rate_index;

  1142.     s->error_protection = ((header >> 16) & 1) ^ 1;

  1143.     s->sample_rate = sample_rate;

  1144. 

  1145.     bitrate_index = (header >> 12) & 0xf;

  1146.     padding = (header >> 9) & 1;

  1147.     //extension = (header >> 8) & 1;

  1148.     s->mode = (header >> 6) & 3;

  1149.     s->mode_ext = (header >> 4) & 3;

  1150.     //copyright = (header >> 3) & 1;

  1151.     //original = (header >> 2) & 1;

  1152.     //emphasis = header & 3;

  1153. 

  1154.     if (s->mode == MPA_MONO)

  1155.         s->nb_channels = 1;

  1156.     else

  1157.         s->nb_channels = 2;

  1158.     

  1159.     if (bitrate_index != 0) {

  1160.         frame_size = mpa_bitrate_tab[s->lsf][s->layer - 1][bitrate_index];

  1161.         s->bit_rate = frame_size * 1000;

  1162.         switch(s->layer) {

  1163.         case 1:

  1164.             frame_size = (frame_size * 12000) / sample_rate;

  1165.             frame_size = (frame_size + padding) * 4;

  1166.             break;

  1167.         case 2:

  1168.             frame_size = (frame_size * 144000) / sample_rate;

  1169.             frame_size += padding;

  1170.             break;

  1171.         default:

  1172.         case 3:

  1173.             frame_size = (frame_size * 144000) / (sample_rate << s->lsf);

  1174.             frame_size += padding;

  1175.             break;

  1176.         }

  1177.         s->frame_size = frame_size;

  1178.     } else {

  1179.         /* if no frame size computed, signal it */

  1180.         if (!s->free_format_frame_size)

  1181.             return 1;

  1182.         /* free format: compute bitrate and real frame size from the

  1183.            frame size we extracted by reading the bitstream */

  1184.         s->frame_size = s->free_format_frame_size;

  1185.         switch(s->layer) {

  1186.         case 1:

  1187.             s->frame_size += padding  * 4;

  1188.             s->bit_rate = (s->frame_size * sample_rate) / 48000;

  1189.             break;

  1190.         case 2:

  1191.             s->frame_size += padding;

  1192.             s->bit_rate = (s->frame_size * sample_rate) / 144000;

  1193.             break;

  1194.         default:

  1195.         case 3:

  1196.             s->frame_size += padding;

  1197.             s->bit_rate = (s->frame_size * (sample_rate << s->lsf)) / 144000;

  1198.             break;

  1199.         }

  1200.     }

  1201.     

  1202. #if defined(DEBUG)

  1203.     printf("layer%d, %d Hz, %d kbits/s, ",

  1204.            s->layer, s->sample_rate, s->bit_rate);

  1205.     if (s->nb_channels == 2) {

  1206.         if (s->layer == 3) {

  1207.             if (s->mode_ext & MODE_EXT_MS_STEREO)

  1208.                 printf("ms-");

  1209.             if (s->mode_ext & MODE_EXT_I_STEREO)

  1210.                 printf("i-");

  1211.         }

  1212.         printf("stereo");

  1213.     } else {

  1214.         printf("mono");

  1215.     }

  1216.     printf("\n");

  1217. #endif

  1218.     return 0;

  1219. }

  1220. 

  1221. /* useful helper to get mpeg audio stream infos. Return -1 if error in

  1222.    header, otherwise the coded frame size in bytes */

  1223. int mpa_decode_header(AVCodecContext *avctx, uint32_t head)

  1224. {

  1225.     MPADecodeContext s1, *s = &s1;

  1226.     memset( s, 0, sizeof(MPADecodeContext) );

  1227. 

  1228.     if (ff_mpa_check_header(head) != 0)

  1229.         return -1;

  1230. 

  1231.     if (decode_header(s, head) != 0) {

  1232.         return -1;

  1233.     }

  1234. 

  1235.     switch(s->layer) {

  1236.     case 1:

  1237.         avctx->frame_size = 384;

  1238.         break;

  1239.     case 2:

  1240.         avctx->frame_size = 1152;

  1241.         break;

  1242.     default:

  1243.     case 3:

  1244.         if (s->lsf)

  1245.             avctx->frame_size = 576;

  1246.         else

  1247.             avctx->frame_size = 1152;

  1248.         break;

  1249.     }

  1250. 

  1251.     avctx->sample_rate = s->sample_rate;

  1252.     avctx->channels = s->nb_channels;

  1253.     avctx->bit_rate = s->bit_rate;

  1254.     avctx->sub_id = s->layer;

  1255.     return s->frame_size;

  1256. }

  1257. 

  1258. /* return the number of decoded frames */

  1259. static int mp_decode_layer1(MPADecodeContext *s)

  1260. {

  1261.     int bound, i, v, n, ch, j, mant;

  1262.     uint8_t allocation[MPA_MAX_CHANNELS][SBLIMIT];

  1263.     uint8_t scale_factors[MPA_MAX_CHANNELS][SBLIMIT];

  1264. 

  1265.     if (s->mode == MPA_JSTEREO) 

  1266.         bound = (s->mode_ext + 1) * 4;

  1267.     else

  1268.         bound = SBLIMIT;

  1269. 

  1270.     /* allocation bits */

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

  1272.         for(ch=0;ch<s->nb_channels;ch++) {

  1273.             allocation[ch][i] = get_bits(&s->gb, 4);

  1274.         }

  1275.     }

  1276.     for(i=bound;i<SBLIMIT;i++) {

  1277.         allocation[0][i] = get_bits(&s->gb, 4);

  1278.     }

  1279. 

  1280.     /* scale factors */

  1281.     for(i=0;i<bound;i++) {

  1282.         for(ch=0;ch<s->nb_channels;ch++) {

  1283.             if (allocation[ch][i])

  1284.                 scale_factors[ch][i] = get_bits(&s->gb, 6);

  1285.         }

  1286.     }

  1287.     for(i=bound;i<SBLIMIT;i++) {

  1288.         if (allocation[0][i]) {

  1289.             scale_factors[0][i] = get_bits(&s->gb, 6);

  1290.             scale_factors[1][i] = get_bits(&s->gb, 6);

  1291.         }

  1292.     }

  1293.     

  1294.     /* compute samples */

  1295.     for(j=0;j<12;j++) {

  1296.         for(i=0;i<bound;i++) {

  1297.             for(ch=0;ch<s->nb_channels;ch++) {

  1298.                 n = allocation[ch][i];

  1299.                 if (n) {

  1300.                     mant = get_bits(&s->gb, n + 1);

  1301.                     v = l1_unscale(n, mant, scale_factors[ch][i]);

  1302.                 } else {

  1303.                     v = 0;

  1304.                 }

  1305.                 s->sb_samples[ch][j][i] = v;

  1306.             }

  1307.         }

  1308.         for(i=bound;i<SBLIMIT;i++) {

  1309.             n = allocation[0][i];

  1310.             if (n) {

  1311.                 mant = get_bits(&s->gb, n + 1);

  1312.                 v = l1_unscale(n, mant, scale_factors[0][i]);

  1313.                 s->sb_samples[0][j][i] = v;

  1314.                 v = l1_unscale(n, mant, scale_factors[1][i]);

  1315.                 s->sb_samples[1][j][i] = v;

  1316.             } else {

  1317.                 s->sb_samples[0][j][i] = 0;

  1318.                 s->sb_samples[1][j][i] = 0;

  1319.             }

  1320.         }

  1321.     }

  1322.     return 12;

  1323. }

  1324. 

  1325. /* bitrate is in kb/s */

  1326. int l2_select_table(int bitrate, int nb_channels, int freq, int lsf)

  1327. {

  1328.     int ch_bitrate, table;

  1329.     

  1330.     ch_bitrate = bitrate / nb_channels;

  1331.     if (!lsf) {

  1332.         if ((freq == 48000 && ch_bitrate >= 56) ||

  1333.             (ch_bitrate >= 56 && ch_bitrate <= 80)) 

  1334.             table = 0;

  1335.         else if (freq != 48000 && ch_bitrate >= 96) 

  1336.             table = 1;

  1337.         else if (freq != 32000 && ch_bitrate <= 48) 

  1338.             table = 2;

  1339.         else 

  1340.             table = 3;

  1341.     } else {

  1342.         table = 4;

  1343.     }

  1344.     return table;

  1345. }

  1346. 

  1347. static int mp_decode_layer2(MPADecodeContext *s)

  1348. {

  1349.     int sblimit; /* number of used subbands */

  1350.     const unsigned char *alloc_table;

  1351.     int table, bit_alloc_bits, i, j, ch, bound, v;

  1352.     unsigned char bit_alloc[MPA_MAX_CHANNELS][SBLIMIT];

  1353.     unsigned char scale_code[MPA_MAX_CHANNELS][SBLIMIT];

  1354.     unsigned char scale_factors[MPA_MAX_CHANNELS][SBLIMIT][3], *sf;

  1355.     int scale, qindex, bits, steps, k, l, m, b;

  1356. 

  1357.     /* select decoding table */

  1358.     table = l2_select_table(s->bit_rate / 1000, s->nb_channels, 

  1359.                             s->sample_rate, s->lsf);

  1360.     sblimit = sblimit_table[table];

  1361.     alloc_table = alloc_tables[table];

  1362. 

  1363.     if (s->mode == MPA_JSTEREO) 

  1364.         bound = (s->mode_ext + 1) * 4;

  1365.     else

  1366.         bound = sblimit;

  1367. 

  1368.     dprintf("bound=%d sblimit=%d\n", bound, sblimit);

  1369. 

  1370.     /* sanity check */

  1371.     if( bound > sblimit ) bound = sblimit;

  1372. 

  1373.     /* parse bit allocation */

  1374.     j = 0;

  1375.     for(i=0;i<bound;i++) {

  1376.         bit_alloc_bits = alloc_table[j];

  1377.         for(ch=0;ch<s->nb_channels;ch++) {

  1378.             bit_alloc[ch][i] = get_bits(&s->gb, bit_alloc_bits);

  1379.         }

  1380.         j += 1 << bit_alloc_bits;

  1381.     }

  1382.     for(i=bound;i<sblimit;i++) {

  1383.         bit_alloc_bits = alloc_table[j];

  1384.         v = get_bits(&s->gb, bit_alloc_bits);

  1385.         bit_alloc[0][i] = v;

  1386.         bit_alloc[1][i] = v;

  1387.         j += 1 << bit_alloc_bits;

  1388.     }

  1389. 

  1390. #ifdef DEBUG

  1391.     {

  1392.         for(ch=0;ch<s->nb_channels;ch++) {

  1393.             for(i=0;i<sblimit;i++)

  1394.                 printf(" %d", bit_alloc[ch][i]);

  1395.             printf("\n");

  1396.         }

  1397.     }

  1398. #endif

  1399. 

  1400.     /* scale codes */

  1401.     for(i=0;i<sblimit;i++) {

  1402.         for(ch=0;ch<s->nb_channels;ch++) {

  1403.             if (bit_alloc[ch][i]) 

  1404.                 scale_code[ch][i] = get_bits(&s->gb, 2);

  1405.         }

  1406.     }

  1407.     

  1408.     /* scale factors */

  1409.     for(i=0;i<sblimit;i++) {

  1410.         for(ch=0;ch<s->nb_channels;ch++) {

  1411.             if (bit_alloc[ch][i]) {

  1412.                 sf = scale_factors[ch][i];

  1413.                 switch(scale_code[ch][i]) {

  1414.                 default:

  1415.                 case 0:

  1416.                     sf[0] = get_bits(&s->gb, 6);

  1417.                     sf[1] = get_bits(&s->gb, 6);

  1418.                     sf[2] = get_bits(&s->gb, 6);

  1419.                     break;

  1420.                 case 2:

  1421.                     sf[0] = get_bits(&s->gb, 6);

  1422.                     sf[1] = sf[0];

  1423.                     sf[2] = sf[0];

  1424.                     break;

  1425.                 case 1:

  1426.                     sf[0] = get_bits(&s->gb, 6);

  1427.                     sf[2] = get_bits(&s->gb, 6);

  1428.                     sf[1] = sf[0];

  1429.                     break;

  1430.                 case 3:

  1431.                     sf[0] = get_bits(&s->gb, 6);

  1432.                     sf[2] = get_bits(&s->gb, 6);

  1433.                     sf[1] = sf[2];

  1434.                     break;

  1435.                 }

  1436.             }

  1437.         }

  1438.     }

  1439. 

  1440. #ifdef DEBUG

  1441.     for(ch=0;ch<s->nb_channels;ch++) {

  1442.         for(i=0;i<sblimit;i++) {

  1443.             if (bit_alloc[ch][i]) {

  1444.                 sf = scale_factors[ch][i];

  1445.                 printf(" %d %d %d", sf[0], sf[1], sf[2]);

  1446.             } else {

  1447.                 printf(" -");

  1448.             }

  1449.         }

  1450.         printf("\n");

  1451.     }

  1452. #endif

  1453. 

  1454.     /* samples */

  1455.     for(k=0;k<3;k++) {

  1456.         for(l=0;l<12;l+=3) {

  1457.             j = 0;

  1458.             for(i=0;i<bound;i++) {

  1459.                 bit_alloc_bits = alloc_table[j];

  1460.                 for(ch=0;ch<s->nb_channels;ch++) {

  1461.                     b = bit_alloc[ch][i];

  1462.                     if (b) {

  1463.                         scale = scale_factors[ch][i][k];

  1464.                         qindex = alloc_table[j+b];

  1465.                         bits = quant_bits[qindex];

  1466.                         if (bits < 0) {

  1467.                             /* 3 values at the same time */

  1468.                             v = get_bits(&s->gb, -bits);

  1469.                             steps = quant_steps[qindex];

  1470.                             s->sb_samples[ch][k * 12 + l + 0][i] = 

  1471.                                 l2_unscale_group(steps, v % steps, scale);

  1472.                             v = v / steps;

  1473.                             s->sb_samples[ch][k * 12 + l + 1][i] = 

  1474.                                 l2_unscale_group(steps, v % steps, scale);

  1475.                             v = v / steps;

  1476.                             s->sb_samples[ch][k * 12 + l + 2][i] = 

  1477.                                 l2_unscale_group(steps, v, scale);

  1478.                         } else {

  1479.                             for(m=0;m<3;m++) {

  1480.                                 v = get_bits(&s->gb, bits);

  1481.                                 v = l1_unscale(bits - 1, v, scale);

  1482.                                 s->sb_samples[ch][k * 12 + l + m][i] = v;

  1483.                             }

  1484.                         }

  1485.                     } else {

  1486.                         s->sb_samples[ch][k * 12 + l + 0][i] = 0;

  1487.                         s->sb_samples[ch][k * 12 + l + 1][i] = 0;

  1488.                         s->sb_samples[ch][k * 12 + l + 2][i] = 0;

  1489.                     }

  1490.                 }

  1491.                 /* next subband in alloc table */

  1492.                 j += 1 << bit_alloc_bits; 

  1493.             }

  1494.             /* XXX: find a way to avoid this duplication of code */

  1495.             for(i=bound;i<sblimit;i++) {

  1496.                 bit_alloc_bits = alloc_table[j];

  1497.                 b = bit_alloc[0][i];

  1498.                 if (b) {

  1499.                     int mant, scale0, scale1;

  1500.                     scale0 = scale_factors[0][i][k];

  1501.                     scale1 = scale_factors[1][i][k];

  1502.                     qindex = alloc_table[j+b];

  1503.                     bits = quant_bits[qindex];

  1504.                     if (bits < 0) {

  1505.                         /* 3 values at the same time */

  1506.                         v = get_bits(&s->gb, -bits);

  1507.                         steps = quant_steps[qindex];

  1508.                         mant = v % steps;

  1509.                         v = v / steps;

  1510.                         s->sb_samples[0][k * 12 + l + 0][i] = 

  1511.                             l2_unscale_group(steps, mant, scale0);

  1512.                         s->sb_samples[1][k * 12 + l + 0][i] = 

  1513.                             l2_unscale_group(steps, mant, scale1);

  1514.                         mant = v % steps;

  1515.                         v = v / steps;

  1516.                         s->sb_samples[0][k * 12 + l + 1][i] = 

  1517.                             l2_unscale_group(steps, mant, scale0);

  1518.                         s->sb_samples[1][k * 12 + l + 1][i] = 

  1519.                             l2_unscale_group(steps, mant, scale1);

  1520.                         s->sb_samples[0][k * 12 + l + 2][i] = 

  1521.                             l2_unscale_group(steps, v, scale0);

  1522.                         s->sb_samples[1][k * 12 + l + 2][i] = 

  1523.                             l2_unscale_group(steps, v, scale1);

  1524.                     } else {

  1525.                         for(m=0;m<3;m++) {

  1526.                             mant = get_bits(&s->gb, bits);

  1527.                             s->sb_samples[0][k * 12 + l + m][i] = 

  1528.                                 l1_unscale(bits - 1, mant, scale0);

  1529.                             s->sb_samples[1][k * 12 + l + m][i] = 

  1530.                                 l1_unscale(bits - 1, mant, scale1);

  1531.                         }

  1532.                     }

  1533.                 } else {

  1534.                     s->sb_samples[0][k * 12 + l + 0][i] = 0;

  1535.                     s->sb_samples[0][k * 12 + l + 1][i] = 0;

  1536.                     s->sb_samples[0][k * 12 + l + 2][i] = 0;

  1537.                     s->sb_samples[1][k * 12 + l + 0][i] = 0;

  1538.                     s->sb_samples[1][k * 12 + l + 1][i] = 0;

  1539.                     s->sb_samples[1][k * 12 + l + 2][i] = 0;

  1540.                 }

  1541.                 /* next subband in alloc table */

  1542.                 j += 1 << bit_alloc_bits; 

  1543.             }

  1544.             /* fill remaining samples to zero */

  1545.             for(i=sblimit;i<SBLIMIT;i++) {

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

  1547.                     s->sb_samples[ch][k * 12 + l + 0][i] = 0;

  1548.                     s->sb_samples[ch][k * 12 + l + 1][i] = 0;

  1549.                     s->sb_samples[ch][k * 12 + l + 2][i] = 0;

  1550.                 }

  1551.             }

  1552.         }

  1553.     }

  1554.     return 3 * 12;

  1555. }

  1556. 

  1557. /*

  1558.  * Seek back in the stream for backstep bytes (at most 511 bytes)

  1559.  */

  1560. static void seek_to_maindata(MPADecodeContext *s, unsigned int backstep)

  1561. {

  1562.     uint8_t *ptr;

  1563. 

  1564.     /* compute current position in stream */

  1565.     ptr = (uint8_t *)(s->gb.buffer + (get_bits_count(&s->gb)>>3));

  1566. 

  1567.     /* copy old data before current one */

  1568.     ptr -= backstep;

  1569.     memcpy(ptr, s->inbuf1[s->inbuf_index ^ 1] + 

  1570.            BACKSTEP_SIZE + s->old_frame_size - backstep, backstep);

  1571.     /* init get bits again */

  1572.     init_get_bits(&s->gb, ptr, (s->frame_size + backstep)*8);

  1573. 

  1574.     /* prepare next buffer */

  1575.     s->inbuf_index ^= 1;

  1576.     s->inbuf = &s->inbuf1[s->inbuf_index][BACKSTEP_SIZE];

  1577.     s->old_frame_size = s->frame_size;

  1578. }

  1579. 

  1580. static inline void lsf_sf_expand(int *slen,

  1581.                                  int sf, int n1, int n2, int n3)

  1582. {

  1583.     if (n3) {

  1584.         slen[3] = sf % n3;

  1585.         sf /= n3;

  1586.     } else {

  1587.         slen[3] = 0;

  1588.     }

  1589.     if (n2) {

  1590.         slen[2] = sf % n2;

  1591.         sf /= n2;

  1592.     } else {

  1593.         slen[2] = 0;

  1594.     }

  1595.     slen[1] = sf % n1;

  1596.     sf /= n1;

  1597.     slen[0] = sf;

  1598. }

  1599. 

  1600. static void exponents_from_scale_factors(MPADecodeContext *s, 

  1601.                                          GranuleDef *g,

  1602.                                          int16_t *exponents)

  1603. {

  1604.     const uint8_t *bstab, *pretab;

  1605.     int len, i, j, k, l, v0, shift, gain, gains[3];

  1606.     int16_t *exp_ptr;

  1607. 

  1608.     exp_ptr = exponents;

  1609.     gain = g->global_gain - 210;

  1610.     shift = g->scalefac_scale + 1;

  1611. 

  1612.     bstab = band_size_long[s->sample_rate_index];

  1613.     pretab = mpa_pretab[g->preflag];

  1614.     for(i=0;i<g->long_end;i++) {

  1615.         v0 = gain - ((g->scale_factors[i] + pretab[i]) << shift);

  1616.         len = bstab[i];

  1617.         for(j=len;j>0;j--)

  1618.             *exp_ptr++ = v0;

  1619.     }

  1620. 

  1621.     if (g->short_start < 13) {

  1622.         bstab = band_size_short[s->sample_rate_index];

  1623.         gains[0] = gain - (g->subblock_gain[0] << 3);

  1624.         gains[1] = gain - (g->subblock_gain[1] << 3);

  1625.         gains[2] = gain - (g->subblock_gain[2] << 3);

  1626.         k = g->long_end;

  1627.         for(i=g->short_start;i<13;i++) {

  1628.             len = bstab[i];

  1629.             for(l=0;l<3;l++) {

  1630.                 v0 = gains[l] - (g->scale_factors[k++] << shift);

  1631.                 for(j=len;j>0;j--)

  1632.                 *exp_ptr++ = v0;

  1633.             }

  1634.         }

  1635.     }

  1636. }

  1637. 

  1638. /* handle n = 0 too */

  1639. static inline int get_bitsz(GetBitContext *s, int n)

  1640. {

  1641.     if (n == 0)

  1642.         return 0;

  1643.     else

  1644.         return get_bits(s, n);

  1645. }

  1646. 

  1647. static int huffman_decode(MPADecodeContext *s, GranuleDef *g,

  1648.                           int16_t *exponents, int end_pos)

  1649. {

  1650.     int s_index;

  1651.     int linbits, code, x, y, l, v, i, j, k, pos;

  1652.     GetBitContext last_gb;

  1653.     VLC *vlc;

  1654.     uint8_t *code_table;

  1655. 

  1656.     /* low frequencies (called big values) */

  1657.     s_index = 0;

  1658.     for(i=0;i<3;i++) {

  1659.         j = g->region_size[i];

  1660.         if (j == 0)

  1661.             continue;

  1662.         /* select vlc table */

  1663.         k = g->table_select[i];

  1664.         l = mpa_huff_data[k][0];

  1665.         linbits = mpa_huff_data[k][1];

  1666.         vlc = &huff_vlc[l];

  1667.         code_table = huff_code_table[l];

  1668. 

  1669.         /* read huffcode and compute each couple */

  1670.         for(;j>0;j--) {

  1671.             if (get_bits_count(&s->gb) >= end_pos)

  1672.                 break;

  1673.             if (code_table) {

  1674.                 code = get_vlc(&s->gb, vlc);

  1675.                 if (code < 0)

  1676.                     return -1;

  1677.                 y = code_table[code];

  1678.                 x = y >> 4;

  1679.                 y = y & 0x0f;

  1680.             } else {

  1681.                 x = 0;

  1682.                 y = 0;

  1683.             }

  1684.             dprintf("region=%d n=%d x=%d y=%d exp=%d\n", 

  1685.                     i, g->region_size[i] - j, x, y, exponents[s_index]);

  1686.             if (x) {

  1687.                 if (x == 15)

  1688.                     x += get_bitsz(&s->gb, linbits);

  1689.                 v = l3_unscale(x, exponents[s_index]);

  1690.                 if (get_bits1(&s->gb))

  1691.                     v = -v;

  1692.             } else {

  1693.                 v = 0;

  1694.             }

  1695.             g->sb_hybrid[s_index++] = v;

  1696.             if (y) {

  1697.                 if (y == 15)

  1698.                     y += get_bitsz(&s->gb, linbits);

  1699.                 v = l3_unscale(y, exponents[s_index]);

  1700.                 if (get_bits1(&s->gb))

  1701.                     v = -v;

  1702.             } else {

  1703.                 v = 0;

  1704.             }

  1705.             g->sb_hybrid[s_index++] = v;

  1706.         }

  1707.     }

  1708.             

  1709.     /* high frequencies */

  1710.     vlc = &huff_quad_vlc[g->count1table_select];

  1711.     last_gb.buffer = NULL;

  1712.     while (s_index <= 572) {

  1713.         pos = get_bits_count(&s->gb);

  1714.         if (pos >= end_pos) {

  1715.             if (pos > end_pos && last_gb.buffer != NULL) {

  1716.                 /* some encoders generate an incorrect size for this

  1717.                    part. We must go back into the data */

  1718.                 s_index -= 4;

  1719.                 s->gb = last_gb;

  1720.             }

  1721.             break;

  1722.         }

  1723.         last_gb= s->gb;

  1724. 

  1725.         code = get_vlc(&s->gb, vlc);

  1726.         dprintf("t=%d code=%d\n", g->count1table_select, code);

  1727.         if (code < 0)

  1728.             return -1;

  1729.         for(i=0;i<4;i++) {

  1730.             if (code & (8 >> i)) {

  1731.                 /* non zero value. Could use a hand coded function for

  1732.                    'one' value */

  1733.                 v = l3_unscale(1, exponents[s_index]);

  1734.                 if(get_bits1(&s->gb))

  1735.                     v = -v;

  1736.             } else {

  1737.                 v = 0;

  1738.             }

  1739.             g->sb_hybrid[s_index++] = v;

  1740.         }

  1741.     }

  1742.     while (s_index < 576)

  1743.         g->sb_hybrid[s_index++] = 0;

  1744.     return 0;

  1745. }

  1746. 

  1747. /* Reorder short blocks from bitstream order to interleaved order. It

  1748.    would be faster to do it in parsing, but the code would be far more

  1749.    complicated */

  1750. static void reorder_block(MPADecodeContext *s, GranuleDef *g)

  1751. {

  1752.     int i, j, k, len;

  1753.     int32_t *ptr, *dst, *ptr1;

  1754.     int32_t tmp[576];

  1755. 

  1756.     if (g->block_type != 2)

  1757.         return;

  1758. 

  1759.     if (g->switch_point) {

  1760.         if (s->sample_rate_index != 8) {

  1761.             ptr = g->sb_hybrid + 36;

  1762.         } else {

  1763.             ptr = g->sb_hybrid + 48;

  1764.         }

  1765.     } else {

  1766.         ptr = g->sb_hybrid;

  1767.     }

  1768.     

  1769.     for(i=g->short_start;i<13;i++) {

  1770.         len = band_size_short[s->sample_rate_index][i];

  1771.         ptr1 = ptr;

  1772.         for(k=0;k<3;k++) {

  1773.             dst = tmp + k;

  1774.             for(j=len;j>0;j--) {

  1775.                 *dst = *ptr++;

  1776.                 dst += 3;

  1777.             }

  1778.         }

  1779.         memcpy(ptr1, tmp, len * 3 * sizeof(int32_t));

  1780.     }

  1781. }

  1782. 

  1783. #define ISQRT2 FIXR(0.70710678118654752440)

  1784. 

  1785. static void compute_stereo(MPADecodeContext *s,

  1786.                            GranuleDef *g0, GranuleDef *g1)

  1787. {

  1788.     int i, j, k, l;

  1789.     int32_t v1, v2;

  1790.     int sf_max, tmp0, tmp1, sf, len, non_zero_found;

  1791.     int32_t (*is_tab)[16];

  1792.     int32_t *tab0, *tab1;

  1793.     int non_zero_found_short[3];

  1794. 

  1795.     /* intensity stereo */

  1796.     if (s->mode_ext & MODE_EXT_I_STEREO) {

  1797.         if (!s->lsf) {

  1798.             is_tab = is_table;

  1799.             sf_max = 7;

  1800.         } else {

  1801.             is_tab = is_table_lsf[g1->scalefac_compress & 1];

  1802.             sf_max = 16;

  1803.         }

  1804.             

  1805.         tab0 = g0->sb_hybrid + 576;

  1806.         tab1 = g1->sb_hybrid + 576;

  1807. 

  1808.         non_zero_found_short[0] = 0;

  1809.         non_zero_found_short[1] = 0;

  1810.         non_zero_found_short[2] = 0;

  1811.         k = (13 - g1->short_start) * 3 + g1->long_end - 3;

  1812.         for(i = 12;i >= g1->short_start;i--) {

  1813.             /* for last band, use previous scale factor */

  1814.             if (i != 11)

  1815.                 k -= 3;

  1816.             len = band_size_short[s->sample_rate_index][i];

  1817.             for(l=2;l>=0;l--) {

  1818.                 tab0 -= len;

  1819.                 tab1 -= len;

  1820.                 if (!non_zero_found_short[l]) {

  1821.                     /* test if non zero band. if so, stop doing i-stereo */

  1822.                     for(j=0;j<len;j++) {

  1823.                         if (tab1[j] != 0) {

  1824.                             non_zero_found_short[l] = 1;

  1825.                             goto found1;

  1826.                         }

  1827.                     }

  1828.                     sf = g1->scale_factors[k + l];

  1829.                     if (sf >= sf_max)

  1830.                         goto found1;

  1831. 

  1832.                     v1 = is_tab[0][sf];

  1833.                     v2 = is_tab[1][sf];

  1834.                     for(j=0;j<len;j++) {

  1835.                         tmp0 = tab0[j];

  1836.                         tab0[j] = MULL(tmp0, v1);

  1837.                         tab1[j] = MULL(tmp0, v2);

  1838.                     }

  1839.                 } else {

  1840.                 found1:

  1841.                     if (s->mode_ext & MODE_EXT_MS_STEREO) {

  1842.                         /* lower part of the spectrum : do ms stereo

  1843.                            if enabled */

  1844.                         for(j=0;j<len;j++) {

  1845.                             tmp0 = tab0[j];

  1846.                             tmp1 = tab1[j];

  1847.                             tab0[j] = MULL(tmp0 + tmp1, ISQRT2);

  1848.                             tab1[j] = MULL(tmp0 - tmp1, ISQRT2);

  1849.                         }

  1850.                     }

  1851.                 }

  1852.             }

  1853.         }

  1854. 

  1855.         non_zero_found = non_zero_found_short[0] | 

  1856.             non_zero_found_short[1] | 

  1857.             non_zero_found_short[2];

  1858. 

  1859.         for(i = g1->long_end - 1;i >= 0;i--) {

  1860.             len = band_size_long[s->sample_rate_index][i];

  1861.             tab0 -= len;

  1862.             tab1 -= len;

  1863.             /* test if non zero band. if so, stop doing i-stereo */

  1864.             if (!non_zero_found) {

  1865.                 for(j=0;j<len;j++) {

  1866.                     if (tab1[j] != 0) {

  1867.                         non_zero_found = 1;

  1868.                         goto found2;

  1869.                     }

  1870.                 }

  1871.                 /* for last band, use previous scale factor */

  1872.                 k = (i == 21) ? 20 : i;

  1873.                 sf = g1->scale_factors[k];

  1874.                 if (sf >= sf_max)

  1875.                     goto found2;

  1876.                 v1 = is_tab[0][sf];

  1877.                 v2 = is_tab[1][sf];

  1878.                 for(j=0;j<len;j++) {

  1879.                     tmp0 = tab0[j];

  1880.                     tab0[j] = MULL(tmp0, v1);

  1881.                     tab1[j] = MULL(tmp0, v2);

  1882.                 }

  1883.             } else {

  1884.             found2:

  1885.                 if (s->mode_ext & MODE_EXT_MS_STEREO) {

  1886.                     /* lower part of the spectrum : do ms stereo

  1887.                        if enabled */

  1888.                     for(j=0;j<len;j++) {

  1889.                         tmp0 = tab0[j];

  1890.                         tmp1 = tab1[j];

  1891.                         tab0[j] = MULL(tmp0 + tmp1, ISQRT2);

  1892.                         tab1[j] = MULL(tmp0 - tmp1, ISQRT2);

  1893.                     }

  1894.                 }

  1895.             }

  1896.         }

  1897.     } else if (s->mode_ext & MODE_EXT_MS_STEREO) {

  1898.         /* ms stereo ONLY */

  1899.         /* NOTE: the 1/sqrt(2) normalization factor is included in the

  1900.            global gain */

  1901.         tab0 = g0->sb_hybrid;

  1902.         tab1 = g1->sb_hybrid;

  1903.         for(i=0;i<576;i++) {

  1904.             tmp0 = tab0[i];

  1905.             tmp1 = tab1[i];

  1906.             tab0[i] = tmp0 + tmp1;

  1907.             tab1[i] = tmp0 - tmp1;

  1908.         }

  1909.     }

  1910. }

  1911. 

  1912. static void compute_antialias_integer(MPADecodeContext *s,

  1913.                               GranuleDef *g)

  1914. {

  1915.     int32_t *ptr, *p0, *p1, *csa;

  1916.     int n, i, j;

  1917. 

  1918.     /* we antialias only "long" bands */

  1919.     if (g->block_type == 2) {

  1920.         if (!g->switch_point)

  1921.             return;

  1922.         /* XXX: check this for 8000Hz case */

  1923.         n = 1;

  1924.     } else {

  1925.         n = SBLIMIT - 1;

  1926.     }

  1927.     

  1928.     ptr = g->sb_hybrid + 18;

  1929.     for(i = n;i > 0;i--) {

  1930.         p0 = ptr - 1;

  1931.         p1 = ptr;

  1932.         csa = &csa_table[0][0];       

  1933.         for(j=0;j<4;j++) {

  1934.             int tmp0 = *p0;

  1935.             int tmp1 = *p1;

  1936. #if 0

  1937.             *p0 = FRAC_RND(MUL64(tmp0, csa[0]) - MUL64(tmp1, csa[1]));

  1938.             *p1 = FRAC_RND(MUL64(tmp0, csa[1]) + MUL64(tmp1, csa[0]));

  1939. #else

  1940.             int64_t tmp2= MUL64(tmp0 + tmp1, csa[0]);

  1941.             *p0 = FRAC_RND(tmp2 - MUL64(tmp1, csa[2]));

  1942.             *p1 = FRAC_RND(tmp2 + MUL64(tmp0, csa[3]));

  1943. #endif

  1944.             p0--; p1++;

  1945.             csa += 4;

  1946.             tmp0 = *p0;

  1947.             tmp1 = *p1;

  1948. #if 0

  1949.             *p0 = FRAC_RND(MUL64(tmp0, csa[0]) - MUL64(tmp1, csa[1]));

  1950.             *p1 = FRAC_RND(MUL64(tmp0, csa[1]) + MUL64(tmp1, csa[0]));

  1951. #else

  1952.             tmp2= MUL64(tmp0 + tmp1, csa[0]);

  1953.             *p0 = FRAC_RND(tmp2 - MUL64(tmp1, csa[2]));

  1954.             *p1 = FRAC_RND(tmp2 + MUL64(tmp0, csa[3]));

  1955. #endif

  1956.             p0--; p1++;

  1957.             csa += 4;

  1958.         }

  1959.         ptr += 18;       

  1960.     }

  1961. }

  1962. 

  1963. static void compute_antialias_float(MPADecodeContext *s,

  1964.                               GranuleDef *g)

  1965. {

  1966.     int32_t *ptr, *p0, *p1;

  1967.     int n, i, j;

  1968. 

  1969.     /* we antialias only "long" bands */

  1970.     if (g->block_type == 2) {

  1971.         if (!g->switch_point)

  1972.             return;

  1973.         /* XXX: check this for 8000Hz case */

  1974.         n = 1;

  1975.     } else {

  1976.         n = SBLIMIT - 1;

  1977.     }

  1978.     

  1979.     ptr = g->sb_hybrid + 18;

  1980.     for(i = n;i > 0;i--) {

  1981.         float *csa = &csa_table_float[0][0];       

  1982.         p0 = ptr - 1;

  1983.         p1 = ptr;

  1984.         for(j=0;j<4;j++) {

  1985.             float tmp0 = *p0;

  1986.             float tmp1 = *p1;

  1987. #if 1

  1988.             *p0 = lrintf(tmp0 * csa[0] - tmp1 * csa[1]);

  1989.             *p1 = lrintf(tmp0 * csa[1] + tmp1 * csa[0]);

  1990. #else

  1991.             float tmp2= (tmp0 + tmp1) * csa[0];

  1992.             *p0 = lrintf(tmp2 - tmp1 * csa[2]);

  1993.             *p1 = lrintf(tmp2 + tmp0 * csa[3]);

  1994. #endif

  1995.             p0--; p1++;

  1996.             csa += 4;

  1997.             tmp0 = *p0;

  1998.             tmp1 = *p1;

  1999. #if 1

  2000.             *p0 = lrintf(tmp0 * csa[0] - tmp1 * csa[1]);

  2001.             *p1 = lrintf(tmp0 * csa[1] + tmp1 * csa[0]);

  2002. #else

  2003.             tmp2= (tmp0 + tmp1) * csa[0];

  2004.             *p0 = lrintf(tmp2 - tmp1 * csa[2]);

  2005.             *p1 = lrintf(tmp2 + tmp0 * csa[3]);

  2006. #endif

  2007.             p0--; p1++;

  2008.             csa += 4;

  2009.         }

  2010.         ptr += 18;       

  2011.     }

  2012. }

  2013. 

  2014. static void compute_imdct(MPADecodeContext *s,

  2015.                           GranuleDef *g, 

  2016.                           int32_t *sb_samples,

  2017.                           int32_t *mdct_buf)

  2018. {

  2019.     int32_t *ptr, *win, *win1, *buf, *buf2, *out_ptr, *ptr1;

  2020.     int32_t in[6];

  2021.     int32_t out[36];

  2022.     int32_t out2[12];

  2023.     int i, j, k, mdct_long_end, v, sblimit;

  2024. 

  2025.     /* find last non zero block */

  2026.     ptr = g->sb_hybrid + 576;

  2027.     ptr1 = g->sb_hybrid + 2 * 18;

  2028.     while (ptr >= ptr1) {

  2029.         ptr -= 6;

  2030.         v = ptr[0] | ptr[1] | ptr[2] | ptr[3] | ptr[4] | ptr[5];

  2031.         if (v != 0)

  2032.             break;

  2033.     }

  2034.     sblimit = ((ptr - g->sb_hybrid) / 18) + 1;

  2035. 

  2036.     if (g->block_type == 2) {

  2037.         /* XXX: check for 8000 Hz */

  2038.         if (g->switch_point)

  2039.             mdct_long_end = 2;

  2040.         else

  2041.             mdct_long_end = 0;

  2042.     } else {

  2043.         mdct_long_end = sblimit;

  2044.     }

  2045. 

  2046.     buf = mdct_buf;

  2047.     ptr = g->sb_hybrid;

  2048.     for(j=0;j<mdct_long_end;j++) {

  2049.         imdct36(out, ptr);

  2050.         /* apply window & overlap with previous buffer */

  2051.         out_ptr = sb_samples + j;

  2052.         /* select window */

  2053.         if (g->switch_point && j < 2)

  2054.             win1 = mdct_win[0];

  2055.         else

  2056.             win1 = mdct_win[g->block_type];

  2057.         /* select frequency inversion */

  2058.         win = win1 + ((4 * 36) & -(j & 1));

  2059.         for(i=0;i<18;i++) {

  2060.             *out_ptr = MULL(out[i], win[i]) + buf[i];

  2061.             buf[i] = MULL(out[i + 18], win[i + 18]);

  2062.             out_ptr += SBLIMIT;

  2063.         }

  2064.         ptr += 18;

  2065.         buf += 18;

  2066.     }

  2067.     for(j=mdct_long_end;j<sblimit;j++) {

  2068.         for(i=0;i<6;i++) {

  2069.             out[i] = 0;

  2070.             out[6 + i] = 0;

  2071.             out[30+i] = 0;

  2072.         }

  2073.         /* select frequency inversion */

  2074.         win = mdct_win[2] + ((4 * 36) & -(j & 1));

  2075.         buf2 = out + 6;

  2076.         for(k=0;k<3;k++) {

  2077.             /* reorder input for short mdct */

  2078.             ptr1 = ptr + k;

  2079.             for(i=0;i<6;i++) {

  2080.                 in[i] = *ptr1;

  2081.                 ptr1 += 3;

  2082.             }

  2083.             imdct12(out2, in);

  2084.             /* apply 12 point window and do small overlap */

  2085.             for(i=0;i<6;i++) {

  2086.                 buf2[i] = MULL(out2[i], win[i]) + buf2[i];

  2087.                 buf2[i + 6] = MULL(out2[i + 6], win[i + 6]);

  2088.             }

  2089.             buf2 += 6;

  2090.         }

  2091.         /* overlap */

  2092.         out_ptr = sb_samples + j;

  2093.         for(i=0;i<18;i++) {

  2094.             *out_ptr = out[i] + buf[i];

  2095.             buf[i] = out[i + 18];

  2096.             out_ptr += SBLIMIT;

  2097.         }

  2098.         ptr += 18;

  2099.         buf += 18;

  2100.     }

  2101.     /* zero bands */

  2102.     for(j=sblimit;j<SBLIMIT;j++) {

  2103.         /* overlap */

  2104.         out_ptr = sb_samples + j;

  2105.         for(i=0;i<18;i++) {

  2106.             *out_ptr = buf[i];

  2107.             buf[i] = 0;

  2108.             out_ptr += SBLIMIT;

  2109.         }

  2110.         buf += 18;

  2111.     }

  2112. }

  2113. 

  2114. #if defined(DEBUG)

  2115. void sample_dump(int fnum, int32_t *tab, int n)

  2116. {

  2117.     static FILE *files[16], *f;

  2118.     char buf[512];

  2119.     int i;

  2120.     int32_t v;

  2121.     

  2122.     f = files[fnum];

  2123.     if (!f) {

  2124.         snprintf(buf, sizeof(buf), "/tmp/out%d.%s.pcm", 

  2125.                 fnum, 

  2126. #ifdef USE_HIGHPRECISION

  2127.                 "hp"

  2128. #else

  2129.                 "lp"

  2130. #endif

  2131.                 );

  2132.         f = fopen(buf, "w");

  2133.         if (!f)

  2134.             return;

  2135.         files[fnum] = f;

  2136.     }

  2137.     

  2138.     if (fnum == 0) {

  2139.         static int pos = 0;

  2140.         printf("pos=%d\n", pos);

  2141.         for(i=0;i<n;i++) {

  2142.             printf(" %0.4f", (double)tab[i] / FRAC_ONE);

  2143.             if ((i % 18) == 17)

  2144.                 printf("\n");

  2145.         }

  2146.         pos += n;

  2147.     }

  2148.     for(i=0;i<n;i++) {

  2149.         /* normalize to 23 frac bits */

  2150.         v = tab[i] << (23 - FRAC_BITS);

  2151.         fwrite(&v, 1, sizeof(int32_t), f);

  2152.     }

  2153. }

  2154. #endif

  2155. 

  2156. 

  2157. /* main layer3 decoding function */

  2158. static int mp_decode_layer3(MPADecodeContext *s)

  2159. {

  2160.     int nb_granules, main_data_begin, private_bits;

  2161.     int gr, ch, blocksplit_flag, i, j, k, n, bits_pos, bits_left;

  2162.     GranuleDef granules[2][2], *g;

  2163.     int16_t exponents[576];

  2164. 

  2165.     /* read side info */

  2166.     if (s->lsf) {

  2167.         main_data_begin = get_bits(&s->gb, 8);

  2168.         if (s->nb_channels == 2)

  2169.             private_bits = get_bits(&s->gb, 2);

  2170.         else

  2171.             private_bits = get_bits(&s->gb, 1);

  2172.         nb_granules = 1;

  2173.     } else {

  2174.         main_data_begin = get_bits(&s->gb, 9);

  2175.         if (s->nb_channels == 2)

  2176.             private_bits = get_bits(&s->gb, 3);

  2177.         else

  2178.             private_bits = get_bits(&s->gb, 5);

  2179.         nb_granules = 2;

  2180.         for(ch=0;ch<s->nb_channels;ch++) {

  2181.             granules[ch][0].scfsi = 0; /* all scale factors are transmitted */

  2182.             granules[ch][1].scfsi = get_bits(&s->gb, 4);

  2183.         }

  2184.     }

  2185.     

  2186.     for(gr=0;gr<nb_granules;gr++) {

  2187.         for(ch=0;ch<s->nb_channels;ch++) {

  2188.             dprintf("gr=%d ch=%d: side_info\n", gr, ch);

  2189.             g = &granules[ch][gr];

  2190.             g->part2_3_length = get_bits(&s->gb, 12);

  2191.             g->big_values = get_bits(&s->gb, 9);

  2192.             g->global_gain = get_bits(&s->gb, 8);

  2193.             /* if MS stereo only is selected, we precompute the

  2194.                1/sqrt(2) renormalization factor */

  2195.             if ((s->mode_ext & (MODE_EXT_MS_STEREO | MODE_EXT_I_STEREO)) == 

  2196.                 MODE_EXT_MS_STEREO)

  2197.                 g->global_gain -= 2;

  2198.             if (s->lsf)

  2199.                 g->scalefac_compress = get_bits(&s->gb, 9);

  2200.             else

  2201.                 g->scalefac_compress = get_bits(&s->gb, 4);

  2202.             blocksplit_flag = get_bits(&s->gb, 1);

  2203.             if (blocksplit_flag) {

  2204.                 g->block_type = get_bits(&s->gb, 2);

  2205.                 if (g->block_type == 0)

  2206.                     return -1;

  2207.                 g->switch_point = get_bits(&s->gb, 1);

  2208.                 for(i=0;i<2;i++)

  2209.                     g->table_select[i] = get_bits(&s->gb, 5);

  2210.                 for(i=0;i<3;i++) 

  2211.                     g->subblock_gain[i] = get_bits(&s->gb, 3);

  2212.                 /* compute huffman coded region sizes */

  2213.                 if (g->block_type == 2)

  2214.                     g->region_size[0] = (36 / 2);

  2215.                 else {

  2216.                     if (s->sample_rate_index <= 2) 

  2217.                         g->region_size[0] = (36 / 2);

  2218.                     else if (s->sample_rate_index != 8) 

  2219.                         g->region_size[0] = (54 / 2);

  2220.                     else

  2221.                         g->region_size[0] = (108 / 2);

  2222.                 }

  2223.                 g->region_size[1] = (576 / 2);

  2224.             } else {

  2225.                 int region_address1, region_address2, l;

  2226.                 g->block_type = 0;

  2227.                 g->switch_point = 0;

  2228.                 for(i=0;i<3;i++)

  2229.                     g->table_select[i] = get_bits(&s->gb, 5);

  2230.                 /* compute huffman coded region sizes */

  2231.                 region_address1 = get_bits(&s->gb, 4);

  2232.                 region_address2 = get_bits(&s->gb, 3);

  2233.                 dprintf("region1=%d region2=%d\n", 

  2234.                         region_address1, region_address2);

  2235.                 g->region_size[0] = 

  2236.                     band_index_long[s->sample_rate_index][region_address1 + 1] >> 1;

  2237.                 l = region_address1 + region_address2 + 2;

  2238.                 /* should not overflow */

  2239.                 if (l > 22)

  2240.                     l = 22;

  2241.                 g->region_size[1] = 

  2242.                     band_index_long[s->sample_rate_index][l] >> 1;

  2243.             }

  2244.             /* convert region offsets to region sizes and truncate

  2245.                size to big_values */

  2246.             g->region_size[2] = (576 / 2);

  2247.             j = 0;

  2248.             for(i=0;i<3;i++) {

  2249.                 k = g->region_size[i];

  2250.                 if (k > g->big_values)

  2251.                     k = g->big_values;

  2252.                 g->region_size[i] = k - j;

  2253.                 j = k;

  2254.             }

  2255. 

  2256.             /* compute band indexes */

  2257.             if (g->block_type == 2) {

  2258.                 if (g->switch_point) {

  2259.                     /* if switched mode, we handle the 36 first samples as

  2260.                        long blocks.  For 8000Hz, we handle the 48 first

  2261.                        exponents as long blocks (XXX: check this!) */

  2262.                     if (s->sample_rate_index <= 2)

  2263.                         g->long_end = 8;

  2264.                     else if (s->sample_rate_index != 8)

  2265.                         g->long_end = 6;

  2266.                     else

  2267.                         g->long_end = 4; /* 8000 Hz */

  2268.                     

  2269.                     if (s->sample_rate_index != 8)

  2270.                         g->short_start = 3;

  2271.                     else

  2272.                         g->short_start = 2; 

  2273.                 } else {

  2274.                     g->long_end = 0;

  2275.                     g->short_start = 0;

  2276.                 }

  2277.             } else {

  2278.                 g->short_start = 13;

  2279.                 g->long_end = 22;

  2280.             }

  2281.             

  2282.             g->preflag = 0;

  2283.             if (!s->lsf)

  2284.                 g->preflag = get_bits(&s->gb, 1);

  2285.             g->scalefac_scale = get_bits(&s->gb, 1);

  2286.             g->count1table_select = get_bits(&s->gb, 1);

  2287.             dprintf("block_type=%d switch_point=%d\n",

  2288.                     g->block_type, g->switch_point);

  2289.         }

  2290.     }

  2291. 

  2292.   if (!s->adu_mode) {

  2293.     /* now we get bits from the main_data_begin offset */

  2294.     dprintf("seekback: %d\n", main_data_begin);

  2295.     seek_to_maindata(s, main_data_begin);

  2296.   }

  2297. 

  2298.     for(gr=0;gr<nb_granules;gr++) {

  2299.         for(ch=0;ch<s->nb_channels;ch++) {

  2300.             g = &granules[ch][gr];

  2301.             

  2302.             bits_pos = get_bits_count(&s->gb);

  2303.             

  2304.             if (!s->lsf) {

  2305.                 uint8_t *sc;

  2306.                 int slen, slen1, slen2;

  2307. 

  2308.                 /* MPEG1 scale factors */

  2309.                 slen1 = slen_table[0][g->scalefac_compress];

  2310.                 slen2 = slen_table[1][g->scalefac_compress];

  2311.                 dprintf("slen1=%d slen2=%d\n", slen1, slen2);

  2312.                 if (g->block_type == 2) {

  2313.                     n = g->switch_point ? 17 : 18;

  2314.                     j = 0;

  2315.                     for(i=0;i<n;i++)

  2316.                         g->scale_factors[j++] = get_bitsz(&s->gb, slen1);

  2317.                     for(i=0;i<18;i++)

  2318.                         g->scale_factors[j++] = get_bitsz(&s->gb, slen2);

  2319.                     for(i=0;i<3;i++)

  2320.                         g->scale_factors[j++] = 0;

  2321.                 } else {

  2322.                     sc = granules[ch][0].scale_factors;

  2323.                     j = 0;

  2324.                     for(k=0;k<4;k++) {

  2325.                         n = (k == 0 ? 6 : 5);

  2326.                         if ((g->scfsi & (0x8 >> k)) == 0) {

  2327.                             slen = (k < 2) ? slen1 : slen2;

  2328.                             for(i=0;i<n;i++)

  2329.                                 g->scale_factors[j++] = get_bitsz(&s->gb, slen);

  2330.                         } else {

  2331.                             /* simply copy from last granule */

  2332.                             for(i=0;i<n;i++) {

  2333.                                 g->scale_factors[j] = sc[j];

  2334.                                 j++;

  2335.                             }

  2336.                         }

  2337.                     }

  2338.                     g->scale_factors[j++] = 0;

  2339.                 }

  2340. #if defined(DEBUG)

  2341.                 {

  2342.                     printf("scfsi=%x gr=%d ch=%d scale_factors:\n", 

  2343.                            g->scfsi, gr, ch);

  2344.                     for(i=0;i<j;i++)

  2345.                         printf(" %d", g->scale_factors[i]);

  2346.                     printf("\n");

  2347.                 }

  2348. #endif

  2349.             } else {

  2350.                 int tindex, tindex2, slen[4], sl, sf;

  2351. 

  2352.                 /* LSF scale factors */

  2353.                 if (g->block_type == 2) {

  2354.                     tindex = g->switch_point ? 2 : 1;

  2355.                 } else {

  2356.                     tindex = 0;

  2357.                 }

  2358.                 sf = g->scalefac_compress;

  2359.                 if ((s->mode_ext & MODE_EXT_I_STEREO) && ch == 1) {

  2360.                     /* intensity stereo case */

  2361.                     sf >>= 1;

  2362.                     if (sf < 180) {

  2363.                         lsf_sf_expand(slen, sf, 6, 6, 0);

  2364.                         tindex2 = 3;

  2365.                     } else if (sf < 244) {

  2366.                         lsf_sf_expand(slen, sf - 180, 4, 4, 0);

  2367.                         tindex2 = 4;

  2368.                     } else {

  2369.                         lsf_sf_expand(slen, sf - 244, 3, 0, 0);

  2370.                         tindex2 = 5;

  2371.                     }

  2372.                 } else {

  2373.                     /* normal case */

  2374.                     if (sf < 400) {

  2375.                         lsf_sf_expand(slen, sf, 5, 4, 4);

  2376.                         tindex2 = 0;

  2377.                     } else if (sf < 500) {

  2378.                         lsf_sf_expand(slen, sf - 400, 5, 4, 0);

  2379.                         tindex2 = 1;

  2380.                     } else {

  2381.                         lsf_sf_expand(slen, sf - 500, 3, 0, 0);

  2382.                         tindex2 = 2;

  2383.                         g->preflag = 1;

  2384.                     }

  2385.                 }

  2386. 

  2387.                 j = 0;

  2388.                 for(k=0;k<4;k++) {

  2389.                     n = lsf_nsf_table[tindex2][tindex][k];

  2390.                     sl = slen[k];

  2391.                     for(i=0;i<n;i++)

  2392.                         g->scale_factors[j++] = get_bitsz(&s->gb, sl);

  2393.                 }

  2394.                 /* XXX: should compute exact size */

  2395.                 for(;j<40;j++)

  2396.                     g->scale_factors[j] = 0;

  2397. #if defined(DEBUG)

  2398.                 {

  2399.                     printf("gr=%d ch=%d scale_factors:\n", 

  2400.                            gr, ch);

  2401.                     for(i=0;i<40;i++)

  2402.                         printf(" %d", g->scale_factors[i]);

  2403.                     printf("\n");

  2404.                 }

  2405. #endif

  2406.             }

  2407. 

  2408.             exponents_from_scale_factors(s, g, exponents);

  2409. 

  2410.             /* read Huffman coded residue */

  2411.             if (huffman_decode(s, g, exponents,

  2412.                                bits_pos + g->part2_3_length) < 0)

  2413.                 return -1;

  2414. #if defined(DEBUG)

  2415.             sample_dump(0, g->sb_hybrid, 576);

  2416. #endif

  2417. 

  2418.             /* skip extension bits */

  2419.             bits_left = g->part2_3_length - (get_bits_count(&s->gb) - bits_pos);

  2420.             if (bits_left < 0) {

  2421.                 dprintf("bits_left=%d\n", bits_left);

  2422.                 return -1;

  2423.             }

  2424.             while (bits_left >= 16) {

  2425.                 skip_bits(&s->gb, 16);

  2426.                 bits_left -= 16;

  2427.             }

  2428.             if (bits_left > 0)

  2429.                 skip_bits(&s->gb, bits_left);

  2430.         } /* ch */

  2431. 

  2432.         if (s->nb_channels == 2)

  2433.             compute_stereo(s, &granules[0][gr], &granules[1][gr]);

  2434. 

  2435.         for(ch=0;ch<s->nb_channels;ch++) {

  2436.             g = &granules[ch][gr];

  2437. 

  2438.             reorder_block(s, g);

  2439. #if defined(DEBUG)

  2440.             sample_dump(0, g->sb_hybrid, 576);

  2441. #endif

  2442.             s->compute_antialias(s, g);

  2443. #if defined(DEBUG)

  2444.             sample_dump(1, g->sb_hybrid, 576);

  2445. #endif

  2446.             compute_imdct(s, g, &s->sb_samples[ch][18 * gr][0], s->mdct_buf[ch]); 

  2447. #if defined(DEBUG)

  2448.             sample_dump(2, &s->sb_samples[ch][18 * gr][0], 576);

  2449. #endif

  2450.         }

  2451.     } /* gr */

  2452.     return nb_granules * 18;

  2453. }

  2454. 

  2455. static int mp_decode_frame(MPADecodeContext *s, 

  2456.                            short *samples)

  2457. {

  2458.     int i, nb_frames, ch;

  2459.     short *samples_ptr;

  2460. 

  2461.     init_get_bits(&s->gb, s->inbuf + HEADER_SIZE, 

  2462.                   (s->inbuf_ptr - s->inbuf - HEADER_SIZE)*8);

  2463.     

  2464.     /* skip error protection field */

  2465.     if (s->error_protection)

  2466.         get_bits(&s->gb, 16);

  2467. 

  2468.     dprintf("frame %d:\n", s->frame_count);

  2469.     switch(s->layer) {

  2470.     case 1:

  2471.         nb_frames = mp_decode_layer1(s);

  2472.         break;

  2473.     case 2:

  2474.         nb_frames = mp_decode_layer2(s);

  2475.         break;

  2476.     case 3:

  2477.     default:

  2478.         nb_frames = mp_decode_layer3(s);

  2479.         break;

  2480.     }

  2481. #if defined(DEBUG)

  2482.     for(i=0;i<nb_frames;i++) {

  2483.         for(ch=0;ch<s->nb_channels;ch++) {

  2484.             int j;

  2485.             printf("%d-%d:", i, ch);

  2486.             for(j=0;j<SBLIMIT;j++)

  2487.                 printf(" %0.6f", (double)s->sb_samples[ch][i][j] / FRAC_ONE);

  2488.             printf("\n");

  2489.         }

  2490.     }

  2491. #endif

  2492.     /* apply the synthesis filter */

  2493.     for(ch=0;ch<s->nb_channels;ch++) {

  2494.         samples_ptr = samples + ch;

  2495.         for(i=0;i<nb_frames;i++) {

  2496.             ff_mpa_synth_filter(s->synth_buf[ch], &(s->synth_buf_offset[ch]),

  2497. 			 window, &s->dither_state,

  2498. 			 samples_ptr, s->nb_channels,

  2499.                          s->sb_samples[ch][i]);

  2500.             samples_ptr += 32 * s->nb_channels;

  2501.         }

  2502.     }

  2503. #ifdef DEBUG

  2504.     s->frame_count++;        

  2505. #endif

  2506.     return nb_frames * 32 * sizeof(short) * s->nb_channels;

  2507. }

  2508. 

  2509. static int decode_frame(AVCodecContext * avctx,

  2510. 			void *data, int *data_size,

  2511. 			uint8_t * buf, int buf_size)

  2512. {

  2513.     MPADecodeContext *s = avctx->priv_data;

  2514.     uint32_t header;

  2515.     uint8_t *buf_ptr;

  2516.     int len, out_size;

  2517.     short *out_samples = data;

  2518. 

  2519.     buf_ptr = buf;

  2520.     while (buf_size > 0) {

  2521. 	len = s->inbuf_ptr - s->inbuf;

  2522. 	if (s->frame_size == 0) {

  2523.             /* special case for next header for first frame in free

  2524.                format case (XXX: find a simpler method) */

  2525.             if (s->free_format_next_header != 0) {

  2526.                 s->inbuf[0] = s->free_format_next_header >> 24;

  2527.                 s->inbuf[1] = s->free_format_next_header >> 16;

  2528.                 s->inbuf[2] = s->free_format_next_header >> 8;

  2529.                 s->inbuf[3] = s->free_format_next_header;

  2530.                 s->inbuf_ptr = s->inbuf + 4;

  2531.                 s->free_format_next_header = 0;

  2532.                 goto got_header;

  2533.             }

  2534. 	    /* no header seen : find one. We need at least HEADER_SIZE

  2535.                bytes to parse it */

  2536. 	    len = HEADER_SIZE - len;

  2537. 	    if (len > buf_size)

  2538. 		len = buf_size;

  2539. 	    if (len > 0) {

  2540. 		memcpy(s->inbuf_ptr, buf_ptr, len);

  2541. 		buf_ptr += len;

  2542. 		buf_size -= len;

  2543. 		s->inbuf_ptr += len;

  2544. 	    }

  2545. 	    if ((s->inbuf_ptr - s->inbuf) >= HEADER_SIZE) {

  2546.             got_header:

  2547. 		header = (s->inbuf[0] << 24) | (s->inbuf[1] << 16) |

  2548. 		    (s->inbuf[2] << 8) | s->inbuf[3];

  2549. 

  2550. 		if (ff_mpa_check_header(header) < 0) {

  2551. 		    /* no sync found : move by one byte (inefficient, but simple!) */

  2552. 		    memmove(s->inbuf, s->inbuf + 1, s->inbuf_ptr - s->inbuf - 1);

  2553. 		    s->inbuf_ptr--;

  2554.                     dprintf("skip %x\n", header);

  2555.                     /* reset free format frame size to give a chance

  2556.                        to get a new bitrate */

  2557.                     s->free_format_frame_size = 0;

  2558. 		} else {

  2559. 		    if (decode_header(s, header) == 1) {

  2560.                         /* free format: prepare to compute frame size */

  2561. 			s->frame_size = -1;

  2562.                     }

  2563.                     /* update codec info */

  2564.                     avctx->sample_rate = s->sample_rate;

  2565.                     avctx->channels = s->nb_channels;

  2566.                     avctx->bit_rate = s->bit_rate;

  2567.                     avctx->sub_id = s->layer;

  2568.                     switch(s->layer) {

  2569.                     case 1:

  2570.                         avctx->frame_size = 384;

  2571.                         break;

  2572.                     case 2:

  2573.                         avctx->frame_size = 1152;

  2574.                         break;

  2575.                     case 3:

  2576.                         if (s->lsf)

  2577.                             avctx->frame_size = 576;

  2578.                         else

  2579.                             avctx->frame_size = 1152;

  2580.                         break;

  2581.                     }

  2582. 		}

  2583. 	    }

  2584.         } else if (s->frame_size == -1) {

  2585.             /* free format : find next sync to compute frame size */

  2586. 	    len = MPA_MAX_CODED_FRAME_SIZE - len;

  2587. 	    if (len > buf_size)

  2588. 		len = buf_size;

  2589.             if (len == 0) {

  2590. 		/* frame too long: resync */

  2591.                 s->frame_size = 0;

  2592. 		memmove(s->inbuf, s->inbuf + 1, s->inbuf_ptr - s->inbuf - 1);

  2593. 		s->inbuf_ptr--;

  2594.             } else {

  2595.                 uint8_t *p, *pend;

  2596.                 uint32_t header1;

  2597.                 int padding;

  2598. 

  2599.                 memcpy(s->inbuf_ptr, buf_ptr, len);

  2600.                 /* check for header */

  2601.                 p = s->inbuf_ptr - 3;

  2602.                 pend = s->inbuf_ptr + len - 4;

  2603.                 while (p <= pend) {

  2604.                     header = (p[0] << 24) | (p[1] << 16) |

  2605.                         (p[2] << 8) | p[3];

  2606.                     header1 = (s->inbuf[0] << 24) | (s->inbuf[1] << 16) |

  2607.                         (s->inbuf[2] << 8) | s->inbuf[3];

  2608.                     /* check with high probability that we have a

  2609.                        valid header */

  2610.                     if ((header & SAME_HEADER_MASK) ==

  2611.                         (header1 & SAME_HEADER_MASK)) {

  2612.                         /* header found: update pointers */

  2613.                         len = (p + 4) - s->inbuf_ptr;

  2614.                         buf_ptr += len;

  2615.                         buf_size -= len;

  2616.                         s->inbuf_ptr = p;

  2617.                         /* compute frame size */

  2618.                         s->free_format_next_header = header;

  2619.                         s->free_format_frame_size = s->inbuf_ptr - s->inbuf;

  2620.                         padding = (header1 >> 9) & 1;

  2621.                         if (s->layer == 1)

  2622.                             s->free_format_frame_size -= padding * 4;

  2623.                         else

  2624.                             s->free_format_frame_size -= padding;

  2625.                         dprintf("free frame size=%d padding=%d\n", 

  2626.                                 s->free_format_frame_size, padding);

  2627.                         decode_header(s, header1);

  2628.                         goto next_data;

  2629.                     }

  2630.                     p++;

  2631.                 }

  2632.                 /* not found: simply increase pointers */

  2633.                 buf_ptr += len;

  2634.                 s->inbuf_ptr += len;

  2635.                 buf_size -= len;

  2636.             }

  2637. 	} else if (len < s->frame_size) {

  2638.             if (s->frame_size > MPA_MAX_CODED_FRAME_SIZE)

  2639.                 s->frame_size = MPA_MAX_CODED_FRAME_SIZE;

  2640. 	    len = s->frame_size - len;

  2641. 	    if (len > buf_size)

  2642. 		len = buf_size;

  2643. 	    memcpy(s->inbuf_ptr, buf_ptr, len);

  2644. 	    buf_ptr += len;

  2645. 	    s->inbuf_ptr += len;

  2646. 	    buf_size -= len;

  2647. 	}

  2648.     next_data:

  2649.         if (s->frame_size > 0 && 

  2650.             (s->inbuf_ptr - s->inbuf) >= s->frame_size) {

  2651.             if (avctx->parse_only) {

  2652.                 /* simply return the frame data */

  2653.                 *(uint8_t **)data = s->inbuf;

  2654.                 out_size = s->inbuf_ptr - s->inbuf;

  2655.             } else {

  2656.                 out_size = mp_decode_frame(s, out_samples);

  2657.             }

  2658. 	    s->inbuf_ptr = s->inbuf;

  2659. 	    s->frame_size = 0;

  2660. 	    *data_size = out_size;

  2661. 	    break;

  2662. 	}

  2663.     }

  2664.     return buf_ptr - buf;

  2665. }

  2666. 

  2667. 

  2668. static int decode_frame_adu(AVCodecContext * avctx,

  2669. 			void *data, int *data_size,

  2670. 			uint8_t * buf, int buf_size)

  2671. {

  2672.     MPADecodeContext *s = avctx->priv_data;

  2673.     uint32_t header;

  2674.     int len, out_size;

  2675.     short *out_samples = data;

  2676. 

  2677.     len = buf_size;

  2678. 

  2679.     // Discard too short frames

  2680.     if (buf_size < HEADER_SIZE) {

  2681.         *data_size = 0;

  2682.         return buf_size;

  2683.     }

  2684. 

  2685. 

  2686.     if (len > MPA_MAX_CODED_FRAME_SIZE)

  2687.         len = MPA_MAX_CODED_FRAME_SIZE;

  2688. 

  2689.     memcpy(s->inbuf, buf, len);

  2690.     s->inbuf_ptr = s->inbuf + len;

  2691. 

  2692.     // Get header and restore sync word

  2693.     header = (s->inbuf[0] << 24) | (s->inbuf[1] << 16) |

  2694.               (s->inbuf[2] << 8) | s->inbuf[3] | 0xffe00000;

  2695. 

  2696.     if (ff_mpa_check_header(header) < 0) { // Bad header, discard frame

  2697.         *data_size = 0;

  2698.         return buf_size;

  2699.     }

  2700. 

  2701.     decode_header(s, header);

  2702.     /* update codec info */

  2703.     avctx->sample_rate = s->sample_rate;

  2704.     avctx->channels = s->nb_channels;

  2705.     avctx->bit_rate = s->bit_rate;

  2706.     avctx->sub_id = s->layer;

  2707. 

  2708.     avctx->frame_size=s->frame_size = len;

  2709. 

  2710.     if (avctx->parse_only) {

  2711.         /* simply return the frame data */

  2712.         *(uint8_t **)data = s->inbuf;

  2713.         out_size = s->inbuf_ptr - s->inbuf;

  2714.     } else {

  2715.         out_size = mp_decode_frame(s, out_samples);

  2716.     }

  2717. 

  2718.     *data_size = out_size;

  2719.     return buf_size;

  2720. }

  2721. 

  2722. 

  2723. AVCodec mp2_decoder =

  2724. {

  2725.     "mp2",

  2726.     CODEC_TYPE_AUDIO,

  2727.     CODEC_ID_MP2,

  2728.     sizeof(MPADecodeContext),

  2729.     decode_init,

  2730.     NULL,

  2731.     NULL,

  2732.     decode_frame,

  2733.     CODEC_CAP_PARSE_ONLY,

  2734. };

  2735. 

  2736. AVCodec mp3_decoder =

  2737. {

  2738.     "mp3",

  2739.     CODEC_TYPE_AUDIO,

  2740.     CODEC_ID_MP3,

  2741.     sizeof(MPADecodeContext),

  2742.     decode_init,

  2743.     NULL,

  2744.     NULL,

  2745.     decode_frame,

  2746.     CODEC_CAP_PARSE_ONLY,

  2747. };

  2748. 

  2749. AVCodec mp3adu_decoder =

  2750. {

  2751.     "mp3adu",

  2752.     CODEC_TYPE_AUDIO,

  2753.     CODEC_ID_MP3ADU,

  2754.     sizeof(MPADecodeContext),

  2755.     decode_init,

  2756.     NULL,

  2757.     NULL,

  2758.     decode_frame_adu,

  2759.     CODEC_CAP_PARSE_ONLY,

  2760. };