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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. //#define DEBUG

  20. #include "avcodec.h"

  21. #include "mpegaudio.h"

  22. 

  23. /*

  24.  * TODO:

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

  26.  *  - test lsf / mpeg25 extensively.

  27.  */

  28. 

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

  30.    audio decoder */

  31. #ifdef CONFIG_MPEGAUDIO_HP

  32. #define USE_HIGHPRECISION

  33. #endif

  34. 

  35. #ifdef USE_HIGHPRECISION

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

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

  38. #else

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

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

  41. #endif

  42. 

  43. #define FRAC_ONE    (1 << FRAC_BITS)

  44. 

  45. #define MULL(a,b) (((INT64)(a) * (INT64)(b)) >> FRAC_BITS)

  46. #define MUL64(a,b) ((INT64)(a) * (INT64)(b))

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

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

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

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

  51. 

  52. #if FRAC_BITS <= 15

  53. typedef INT16 MPA_INT;

  54. #else

  55. typedef INT32 MPA_INT;

  56. #endif

  57. 

  58. /****************/

  59. 

  60. #define HEADER_SIZE 4

  61. #define BACKSTEP_SIZE 512

  62. 

  63. typedef struct MPADecodeContext {

  64.     UINT8 inbuf1[2][MPA_MAX_CODED_FRAME_SIZE + BACKSTEP_SIZE];	/* input buffer */

  65.     int inbuf_index;

  66.     UINT8 *inbuf_ptr, *inbuf;

  67.     int frame_size;

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

  69.                                    (zero if currently unknown) */

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

  71.     UINT32 free_format_next_header; 

  72.     int error_protection;

  73.     int layer;

  74.     int sample_rate;

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

  76.     int bit_rate;

  77.     int old_frame_size;

  78.     GetBitContext gb;

  79.     int nb_channels;

  80.     int mode;

  81.     int mode_ext;

  82.     int lsf;

  83.     MPA_INT synth_buf[MPA_MAX_CHANNELS][512 * 2];

  84.     int synth_buf_offset[MPA_MAX_CHANNELS];

  85.     INT32 sb_samples[MPA_MAX_CHANNELS][36][SBLIMIT];

  86.     INT32 mdct_buf[MPA_MAX_CHANNELS][SBLIMIT * 18]; /* previous samples, for layer 3 MDCT */

  87. #ifdef DEBUG

  88.     int frame_count;

  89. #endif

  90. } MPADecodeContext;

  91. 

  92. /* layer 3 "granule" */

  93. typedef struct GranuleDef {

  94.     UINT8 scfsi;

  95.     int part2_3_length;

  96.     int big_values;

  97.     int global_gain;

  98.     int scalefac_compress;

  99.     UINT8 block_type;

  100.     UINT8 switch_point;

  101.     int table_select[3];

  102.     int subblock_gain[3];

  103.     UINT8 scalefac_scale;

  104.     UINT8 count1table_select;

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

  106.     int preflag;

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

  108.     UINT8 scale_factors[40];

  109.     INT32 sb_hybrid[SBLIMIT * 18]; /* 576 samples */

  110. } GranuleDef;

  111. 

  112. #define MODE_EXT_MS_STEREO 2

  113. #define MODE_EXT_I_STEREO  1

  114. 

  115. /* layer 3 huffman tables */

  116. typedef struct HuffTable {

  117.     int xsize;

  118.     const UINT8 *bits;

  119.     const UINT16 *codes;

  120. } HuffTable;

  121. 

  122. #include "mpegaudiodectab.h"

  123. 

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

  125. static VLC huff_vlc[16]; 

  126. static UINT8 *huff_code_table[16];

  127. static VLC huff_quad_vlc[2];

  128. /* computed from band_size_long */

  129. static UINT16 band_index_long[9][23];

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

  131. #define TABLE_4_3_SIZE (8191 + 16)

  132. static INT8  *table_4_3_exp;

  133. #if FRAC_BITS <= 15

  134. static UINT16 *table_4_3_value;

  135. #else

  136. static UINT32 *table_4_3_value;

  137. #endif

  138. /* intensity stereo coef table */

  139. static INT32 is_table[2][16];

  140. static INT32 is_table_lsf[2][2][16];

  141. static INT32 csa_table[8][2];

  142. static INT32 mdct_win[8][36];

  143. 

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

  145. static UINT16 scale_factor_modshift[64];

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

  147. static INT32 scale_factor_mult[15][3];

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

  149. 

  150. #define SCALE_GEN(v) \

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

  152. 

  153. static INT32 scale_factor_mult2[3][3] = {

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

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

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

  157. };

  158. 

  159. /* 2^(n/4) */

  160. static UINT32 scale_factor_mult3[4] = {

  161.     FIXR(1.0),

  162.     FIXR(1.18920711500272106671),

  163.     FIXR(1.41421356237309504880),

  164.     FIXR(1.68179283050742908605),

  165. };

  166. 

  167. static MPA_INT window[512];

  168.     

  169. /* layer 1 unscaling */

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

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

  172. {

  173.     int shift, mod;

  174.     INT64 val;

  175. 

  176.     shift = scale_factor_modshift[scale_factor];

  177.     mod = shift & 3;

  178.     shift >>= 2;

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

  180.     shift += n;

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

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

  183. }

  184. 

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

  186. {

  187.     int shift, mod, val;

  188. 

  189.     shift = scale_factor_modshift[scale_factor];

  190.     mod = shift & 3;

  191.     shift >>= 2;

  192. 

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

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

  195.     if (shift > 0)

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

  197.     return val;

  198. }

  199. 

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

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

  202. {

  203. #if FRAC_BITS <= 15    

  204.     unsigned int m;

  205. #else

  206.     UINT64 m;

  207. #endif

  208.     int e;

  209. 

  210.     e = table_4_3_exp[value];

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

  212.     e = FRAC_BITS - e;

  213. #if FRAC_BITS <= 15    

  214.     if (e > 31)

  215.         e = 31;

  216. #endif

  217.     m = table_4_3_value[value];

  218. #if FRAC_BITS <= 15    

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

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

  221.     return m;

  222. #else

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

  224.     m = (m + (UINT64_C(1) << (e-1))) >> e;

  225.     return m;

  226. #endif

  227. }

  228. 

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

  230. #define DEV_ORDER 13

  231. 

  232. #define POW_FRAC_BITS 24

  233. #define POW_FRAC_ONE    (1 << POW_FRAC_BITS)

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

  235. #define POW_MULL(a,b) (((INT64)(a) * (INT64)(b)) >> POW_FRAC_BITS)

  236. 

  237. static int dev_4_3_coefs[DEV_ORDER];

  238. 

  239. static int pow_mult3[3] = {

  240.     POW_FIX(1.0),

  241.     POW_FIX(1.25992104989487316476),

  242.     POW_FIX(1.58740105196819947474),

  243. };

  244. 

  245. static void int_pow_init(void)

  246. {

  247.     int i, a;

  248. 

  249.     a = POW_FIX(1.0);

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

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

  252.         dev_4_3_coefs[i] = a;

  253.     }

  254. }

  255. 

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

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

  258. {

  259.     int e, er, eq, j;

  260.     int a, a1;

  261.     

  262.     /* renormalize */

  263.     a = i;

  264.     e = POW_FRAC_BITS;

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

  266.         a = a << 1;

  267.         e--;

  268.     }

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

  270.     a1 = 0;

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

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

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

  274.     /* exponent compute (exact) */

  275.     e = e * 4;

  276.     er = e % 3;

  277.     eq = e / 3;

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

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

  280.         a = a >> 1;

  281.         eq++;

  282.     }

  283.     /* convert to float */

  284.     while (a < POW_FRAC_ONE) {

  285.         a = a << 1;

  286.         eq--;

  287.     }

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

  289. #if POW_FRAC_BITS > FRAC_BITS

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

  291.     /* correct overflow */

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

  293.         a = a >> 1;

  294.         eq++;

  295.     }

  296. #endif

  297.     *exp_ptr = eq;

  298.     return a;

  299. }

  300. 

  301. static int decode_init(AVCodecContext * avctx)

  302. {

  303.     MPADecodeContext *s = avctx->priv_data;

  304.     static int init=0;

  305.     int i, j, k;

  306. 

  307.     if(!init) {

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

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

  310.             int shift, mod;

  311.             /* 1.0 (i = 3) is normalized to 2 ^ FRAC_BITS */

  312.             shift = (i / 3);

  313.             mod = i % 3;

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

  315.         }

  316. 

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

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

  319.             int n, norm;

  320.             n = i + 2;

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

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

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

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

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

  326.                     i, norm, 

  327.                     scale_factor_mult[i][0],

  328.                     scale_factor_mult[i][1],

  329.                     scale_factor_mult[i][2]);

  330.         }

  331.         

  332.         /* window */

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

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

  335.             int v;

  336.             v = mpa_enwindow[i];

  337. #if WFRAC_BITS < 16

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

  339. #endif

  340.             window[i] = v;

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

  342.                 v = -v;

  343.             if (i != 0)

  344.                 window[512 - i] = v;

  345.         }

  346.         

  347.         /* huffman decode tables */

  348.         huff_code_table[0] = NULL;

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

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

  351.             int xsize, n, x, y;

  352.             UINT8 *code_table;

  353. 

  354.             xsize = h->xsize;

  355.             n = xsize * xsize;

  356.             /* XXX: fail test */

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

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

  359.             

  360.             code_table = av_mallocz(n);

  361.             j = 0;

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

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

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

  365.             }

  366.             huff_code_table[i] = code_table;

  367.         }

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

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

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

  371.         }

  372. 

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

  374.             k = 0;

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

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

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

  378.             }

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

  380.         }

  381. 

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

  383. 	if (!av_mallocz_static(&table_4_3_exp,

  384. 			       TABLE_4_3_SIZE * sizeof(table_4_3_exp[0])))

  385. 	    return -1;

  386. 	if (!av_mallocz_static(&table_4_3_value,

  387. 			       TABLE_4_3_SIZE * sizeof(table_4_3_value[0])))

  388.             return -1;

  389.         

  390.         int_pow_init();

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

  392.             int e, m;

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

  394. #if 0

  395.             /* test code */

  396.             {

  397.                 double f, fm;

  398.                 int e1, m1;

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

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

  401.                 m1 = FIXR(2 * fm);

  402. #if FRAC_BITS <= 15

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

  404.                     m1 = m1 >> 1;

  405.                     e1++;

  406.                 }

  407. #endif

  408.                 e1--;

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

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

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

  412.                 }

  413.             }

  414. #endif

  415.             /* normalized to FRAC_BITS */

  416.             table_4_3_value[i] = m;

  417.             table_4_3_exp[i] = e;

  418.         }

  419.         

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

  421.             float f;

  422.             int v;

  423.             if (i != 6) {

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

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

  426.             } else {

  427.                 v = FIXR(1.0);

  428.             }

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

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

  431.         }

  432.         /* invalid values */

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

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

  435. 

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

  437.             double f;

  438.             int e, k;

  439. 

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

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

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

  443.                 k = i & 1;

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

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

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

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

  448.             }

  449.         }

  450. 

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

  452.             float ci, cs, ca;

  453.             ci = ci_table[i];

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

  455.             ca = cs * ci;

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

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

  458.         }

  459. 

  460.         /* compute mdct windows */

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

  462.             int v;

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

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

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

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

  467.         }

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

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

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

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

  472. 

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

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

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

  476.         }

  477. 

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

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

  480.         

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

  482.            the sign of the right window coefs */

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

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

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

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

  487.             }

  488.         }

  489. 

  490. #if defined(DEBUG)

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

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

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

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

  495.             printf("\n");

  496.         }

  497. #endif

  498.         init = 1;

  499.     }

  500. 

  501.     s->inbuf_index = 0;

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

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

  504. #ifdef DEBUG

  505.     s->frame_count = 0;

  506. #endif

  507.     return 0;

  508. }

  509. 

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

  511. 

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

  513. 

  514. #define COS0_0  FIXR(0.50060299823519630134)

  515. #define COS0_1  FIXR(0.50547095989754365998)

  516. #define COS0_2  FIXR(0.51544730992262454697)

  517. #define COS0_3  FIXR(0.53104259108978417447)

  518. #define COS0_4  FIXR(0.55310389603444452782)

  519. #define COS0_5  FIXR(0.58293496820613387367)

  520. #define COS0_6  FIXR(0.62250412303566481615)

  521. #define COS0_7  FIXR(0.67480834145500574602)

  522. #define COS0_8  FIXR(0.74453627100229844977)

  523. #define COS0_9  FIXR(0.83934964541552703873)

  524. #define COS0_10 FIXR(0.97256823786196069369)

  525. #define COS0_11 FIXR(1.16943993343288495515)

  526. #define COS0_12 FIXR(1.48416461631416627724)

  527. #define COS0_13 FIXR(2.05778100995341155085)

  528. #define COS0_14 FIXR(3.40760841846871878570)

  529. #define COS0_15 FIXR(10.19000812354805681150)

  530. 

  531. #define COS1_0 FIXR(0.50241928618815570551)

  532. #define COS1_1 FIXR(0.52249861493968888062)

  533. #define COS1_2 FIXR(0.56694403481635770368)

  534. #define COS1_3 FIXR(0.64682178335999012954)

  535. #define COS1_4 FIXR(0.78815462345125022473)

  536. #define COS1_5 FIXR(1.06067768599034747134)

  537. #define COS1_6 FIXR(1.72244709823833392782)

  538. #define COS1_7 FIXR(5.10114861868916385802)

  539. 

  540. #define COS2_0 FIXR(0.50979557910415916894)

  541. #define COS2_1 FIXR(0.60134488693504528054)

  542. #define COS2_2 FIXR(0.89997622313641570463)

  543. #define COS2_3 FIXR(2.56291544774150617881)

  544. 

  545. #define COS3_0 FIXR(0.54119610014619698439)

  546. #define COS3_1 FIXR(1.30656296487637652785)

  547. 

  548. #define COS4_0 FIXR(0.70710678118654752439)

  549. 

  550. /* butterfly operator */

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

  552. {\

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

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

  555.     tab[a] = tmp0;\

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

  557. }

  558. 

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

  560. {\

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

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

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

  564. }

  565. 

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

  567. {\

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

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

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

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

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

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

  574. }

  575. 

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

  577. 

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

  579. static void dct32(INT32 *out, INT32 *tab)

  580. {

  581.     int tmp0, tmp1;

  582. 

  583.     /* pass 1 */

  584.     BF(0, 31, COS0_0);

  585.     BF(1, 30, COS0_1);

  586.     BF(2, 29, COS0_2);

  587.     BF(3, 28, COS0_3);

  588.     BF(4, 27, COS0_4);

  589.     BF(5, 26, COS0_5);

  590.     BF(6, 25, COS0_6);

  591.     BF(7, 24, COS0_7);

  592.     BF(8, 23, COS0_8);

  593.     BF(9, 22, COS0_9);

  594.     BF(10, 21, COS0_10);

  595.     BF(11, 20, COS0_11);

  596.     BF(12, 19, COS0_12);

  597.     BF(13, 18, COS0_13);

  598.     BF(14, 17, COS0_14);

  599.     BF(15, 16, COS0_15);

  600. 

  601.     /* pass 2 */

  602.     BF(0, 15, COS1_0);

  603.     BF(1, 14, COS1_1);

  604.     BF(2, 13, COS1_2);

  605.     BF(3, 12, COS1_3);

  606.     BF(4, 11, COS1_4);

  607.     BF(5, 10, COS1_5);

  608.     BF(6,  9, COS1_6);

  609.     BF(7,  8, COS1_7);

  610.     

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

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

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

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

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

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

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

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

  619.     

  620.     /* pass 3 */

  621.     BF(0, 7, COS2_0);

  622.     BF(1, 6, COS2_1);

  623.     BF(2, 5, COS2_2);

  624.     BF(3, 4, COS2_3);

  625.     

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

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

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

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

  630.     

  631.     BF(16, 23, COS2_0);

  632.     BF(17, 22, COS2_1);

  633.     BF(18, 21, COS2_2);

  634.     BF(19, 20, COS2_3);

  635.     

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

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

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

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

  640. 

  641.     /* pass 4 */

  642.     BF(0, 3, COS3_0);

  643.     BF(1, 2, COS3_1);

  644.     

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

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

  647.     

  648.     BF(8, 11, COS3_0);

  649.     BF(9, 10, COS3_1);

  650.     

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

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

  653.     

  654.     BF(16, 19, COS3_0);

  655.     BF(17, 18, COS3_1);

  656.     

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

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

  659.     

  660.     BF(24, 27, COS3_0);

  661.     BF(25, 26, COS3_1);

  662.     

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

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

  665.     

  666.     /* pass 5 */

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

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

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

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

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

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

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

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

  675.     

  676.     /* pass 6 */

  677.     

  678.     ADD( 8, 12);

  679.     ADD(12, 10);

  680.     ADD(10, 14);

  681.     ADD(14,  9);

  682.     ADD( 9, 13);

  683.     ADD(13, 11);

  684.     ADD(11, 15);

  685. 

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  702.     

  703.     ADD(24, 28);

  704.     ADD(28, 26);

  705.     ADD(26, 30);

  706.     ADD(30, 25);

  707.     ADD(25, 29);

  708.     ADD(29, 27);

  709.     ADD(27, 31);

  710. 

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  727. }

  728. 

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

  730. 

  731. #if FRAC_BITS <= 15

  732. 

  733. #define OUT_SAMPLE(sum)\

  734. {\

  735.     int sum1;\

  736.     sum1 = (sum + (1 << (OUT_SHIFT - 1))) >> OUT_SHIFT;\

  737.     if (sum1 < -32768)\

  738.         sum1 = -32768;\

  739.     else if (sum1 > 32767)\

  740.         sum1 = 32767;\

  741.     *samples = sum1;\

  742.     samples += incr;\

  743. }

  744. 

  745. #define SUM8(off, op)                           \

  746. {                                               \

  747.     sum op w[0 * 64 + off] * p[0 * 64];\

  748.     sum op w[1 * 64 + off] * p[1 * 64];\

  749.     sum op w[2 * 64 + off] * p[2 * 64];\

  750.     sum op w[3 * 64 + off] * p[3 * 64];\

  751.     sum op w[4 * 64 + off] * p[4 * 64];\

  752.     sum op w[5 * 64 + off] * p[5 * 64];\

  753.     sum op w[6 * 64 + off] * p[6 * 64];\

  754.     sum op w[7 * 64 + off] * p[7 * 64];\

  755. }

  756. 

  757. #else

  758. 

  759. #define OUT_SAMPLE(sum)\

  760. {\

  761.     int sum1;\

  762.     sum1 = (int)((sum + (INT64_C(1) << (OUT_SHIFT - 1))) >> OUT_SHIFT);\

  763.     if (sum1 < -32768)\

  764.         sum1 = -32768;\

  765.     else if (sum1 > 32767)\

  766.         sum1 = 32767;\

  767.     *samples = sum1;\

  768.     samples += incr;\

  769. }

  770. 

  771. #define SUM8(off, op)                           \

  772. {                                               \

  773.     sum op MUL64(w[0 * 64 + off], p[0 * 64]);\

  774.     sum op MUL64(w[1 * 64 + off], p[1 * 64]);\

  775.     sum op MUL64(w[2 * 64 + off], p[2 * 64]);\

  776.     sum op MUL64(w[3 * 64 + off], p[3 * 64]);\

  777.     sum op MUL64(w[4 * 64 + off], p[4 * 64]);\

  778.     sum op MUL64(w[5 * 64 + off], p[5 * 64]);\

  779.     sum op MUL64(w[6 * 64 + off], p[6 * 64]);\

  780.     sum op MUL64(w[7 * 64 + off], p[7 * 64]);\

  781. }

  782. 

  783. #endif

  784. 

  785. /* 32 sub band synthesis filter. Input: 32 sub band samples, Output:

  786.    32 samples. */

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

  788. static void synth_filter(MPADecodeContext *s1,

  789.                          int ch, INT16 *samples, int incr, 

  790.                          INT32 sb_samples[SBLIMIT])

  791. {

  792.     INT32 tmp[32];

  793.     register MPA_INT *synth_buf, *p;

  794.     register MPA_INT *w;

  795.     int j, offset, v;

  796. #if FRAC_BITS <= 15

  797.     int sum;

  798. #else

  799.     INT64 sum;

  800. #endif

  801. 

  802.     dct32(tmp, sb_samples);

  803.     

  804.     offset = s1->synth_buf_offset[ch];

  805.     synth_buf = s1->synth_buf[ch] + offset;

  806. 

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

  808.         v = tmp[j];

  809. #if FRAC_BITS <= 15

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

  811.            sound */

  812.         if (v > 32767)

  813.             v = 32767;

  814.         else if (v < -32768)

  815.             v = -32768;

  816. #endif

  817.         synth_buf[j] = v;

  818.     }

  819.     /* copy to avoid wrap */

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

  821. 

  822.     w = window;

  823.     for(j=0;j<16;j++) {

  824.         sum = 0;

  825.         p = synth_buf + 16 + j;    /* 0-15  */

  826.         SUM8(0, +=);

  827.         p = synth_buf + 48 - j;    /* 32-47 */

  828.         SUM8(32, -=);

  829.         OUT_SAMPLE(sum);

  830.         w++;

  831.     }

  832.     

  833.     p = synth_buf + 32; /* 48 */

  834.     sum = 0;

  835.     SUM8(32, -=);

  836.     OUT_SAMPLE(sum);

  837.     w++;

  838. 

  839.     for(j=17;j<32;j++) {

  840.         sum = 0;

  841.         p = synth_buf + 48 - j; /* 17-31 */

  842.         SUM8(0, -=);

  843.         p = synth_buf + 16 + j; /* 49-63 */

  844.         SUM8(32, -=);

  845.         OUT_SAMPLE(sum);

  846.         w++;

  847.     }

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

  849.     s1->synth_buf_offset[ch] = offset;

  850. }

  851. 

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

  853. #define C1  FIXR(0.99144486137381041114)

  854. #define C3  FIXR(0.92387953251128675612)

  855. #define C5  FIXR(0.79335334029123516458)

  856. #define C7  FIXR(0.60876142900872063941)

  857. #define C9  FIXR(0.38268343236508977173)

  858. #define C11 FIXR(0.13052619222005159154)

  859. 

  860. /* 12 points IMDCT. We compute it "by hand" by factorizing obvious

  861.    cases. */

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

  863. {

  864.     int tmp;

  865.     INT64 in1_3, in1_9, in4_3, in4_9;

  866. 

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

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

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

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

  871.     

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

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

  874.     out[0] = tmp;

  875.     out[5] = -tmp;

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

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

  878.     out[1] = tmp;

  879.     out[4] = -tmp;

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

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

  882.     out[2] = tmp;

  883.     out[3] = -tmp;

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

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

  886.     out[6] = tmp;

  887.     out[11] = tmp;

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

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

  890.     out[7] = tmp;

  891.     out[10] = tmp;

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

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

  894.     out[8] = tmp;

  895.     out[9] = tmp;

  896. }

  897. 

  898. #undef C1

  899. #undef C3

  900. #undef C5

  901. #undef C7

  902. #undef C9

  903. #undef C11

  904. 

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

  906. #define C1 FIXR(0.98480775301220805936)

  907. #define C2 FIXR(0.93969262078590838405)

  908. #define C3 FIXR(0.86602540378443864676)

  909. #define C4 FIXR(0.76604444311897803520)

  910. #define C5 FIXR(0.64278760968653932632)

  911. #define C6 FIXR(0.5)

  912. #define C7 FIXR(0.34202014332566873304)

  913. #define C8 FIXR(0.17364817766693034885)

  914. 

  915. /* 0.5 / cos(pi*(2*i+1)/36) */

  916. static const int icos36[9] = {

  917.     FIXR(0.50190991877167369479),

  918.     FIXR(0.51763809020504152469),

  919.     FIXR(0.55168895948124587824),

  920.     FIXR(0.61038729438072803416),

  921.     FIXR(0.70710678118654752439),

  922.     FIXR(0.87172339781054900991),

  923.     FIXR(1.18310079157624925896),

  924.     FIXR(1.93185165257813657349),

  925.     FIXR(5.73685662283492756461),

  926. };

  927. 

  928. static const int icos72[18] = {

  929.     /* 0.5 / cos(pi*(2*i+19)/72) */

  930.     FIXR(0.74009361646113053152),

  931.     FIXR(0.82133981585229078570),

  932.     FIXR(0.93057949835178895673),

  933.     FIXR(1.08284028510010010928),

  934.     FIXR(1.30656296487637652785),

  935.     FIXR(1.66275476171152078719),

  936.     FIXR(2.31011315767264929558),

  937.     FIXR(3.83064878777019433457),

  938.     FIXR(11.46279281302667383546),

  939. 

  940.     /* 0.5 / cos(pi*(2*(i + 18) +19)/72) */

  941.     FIXR(-0.67817085245462840086),

  942.     FIXR(-0.63023620700513223342),

  943.     FIXR(-0.59284452371708034528),

  944.     FIXR(-0.56369097343317117734),

  945.     FIXR(-0.54119610014619698439),

  946.     FIXR(-0.52426456257040533932),

  947.     FIXR(-0.51213975715725461845),

  948.     FIXR(-0.50431448029007636036),

  949.     FIXR(-0.50047634258165998492),

  950. };

  951. 

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

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

  954. {

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

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

  957.     INT64 in3_3, in6_6;

  958. 

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

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

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

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

  963. 

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

  965.         tmp1 = tmp + j;

  966.         in1 = in + j;

  967. 

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

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

  970. 

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  991.     }

  992. 

  993.     i = 0;

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

  995.         t0 = tmp[i];

  996.         t1 = tmp[i + 2];

  997.         s0 = t1 + t0;

  998.         s2 = t1 - t0;

  999. 

  1000.         t2 = tmp[i + 1];

  1001.         t3 = tmp[i + 3];

  1002.         s1 = MULL(t3 + t2, icos36[j]);

  1003.         s3 = MULL(t3 - t2, icos36[8 - j]);

  1004.         

  1005.         t0 = MULL(s0 + s1, icos72[9 + 8 - j]);

  1006.         t1 = MULL(s0 - s1, icos72[8 - j]);

  1007.         out[18 + 9 + j] = t0;

  1008.         out[18 + 8 - j] = t0;

  1009.         out[9 + j] = -t1;

  1010.         out[8 - j] = t1;

  1011.         

  1012.         t0 = MULL(s2 + s3, icos72[9+j]);

  1013.         t1 = MULL(s2 - s3, icos72[j]);

  1014.         out[18 + 9 + (8 - j)] = t0;

  1015.         out[18 + j] = t0;

  1016.         out[9 + (8 - j)] = -t1;

  1017.         out[j] = t1;

  1018.         i += 4;

  1019.     }

  1020. 

  1021.     s0 = tmp[16];

  1022.     s1 = MULL(tmp[17], icos36[4]);

  1023.     t0 = MULL(s0 + s1, icos72[9 + 4]);

  1024.     t1 = MULL(s0 - s1, icos72[4]);

  1025.     out[18 + 9 + 4] = t0;

  1026.     out[18 + 8 - 4] = t0;

  1027.     out[9 + 4] = -t1;

  1028.     out[8 - 4] = t1;

  1029. }

  1030. 

  1031. /* fast header check for resync */

  1032. static int check_header(UINT32 header)

  1033. {

  1034.     /* header */

  1035.     if ((header & 0xffe00000) != 0xffe00000)

  1036. 	return -1;

  1037.     /* layer check */

  1038.     if (((header >> 17) & 3) == 0)

  1039. 	return -1;

  1040.     /* bit rate */

  1041.     if (((header >> 12) & 0xf) == 0xf)

  1042. 	return -1;

  1043.     /* frequency */

  1044.     if (((header >> 10) & 3) == 3)

  1045. 	return -1;

  1046.     return 0;

  1047. }

  1048. 

  1049. /* header + layer + bitrate + freq + lsf/mpeg25 */

  1050. #define SAME_HEADER_MASK \

  1051.    (0xffe00000 | (3 << 17) | (0xf << 12) | (3 << 10) | (3 << 19))

  1052. 

  1053. /* header decoding. MUST check the header before because no

  1054.    consistency check is done there. Return 1 if free format found and

  1055.    that the frame size must be computed externally */

  1056. static int decode_header(MPADecodeContext *s, UINT32 header)

  1057. {

  1058.     int sample_rate, frame_size, mpeg25, padding;

  1059.     int sample_rate_index, bitrate_index;

  1060.     if (header & (1<<20)) {

  1061.         s->lsf = (header & (1<<19)) ? 0 : 1;

  1062.         mpeg25 = 0;

  1063.     } else {

  1064.         s->lsf = 1;

  1065.         mpeg25 = 1;

  1066.     }

  1067.     

  1068.     s->layer = 4 - ((header >> 17) & 3);

  1069.     /* extract frequency */

  1070.     sample_rate_index = (header >> 10) & 3;

  1071.     sample_rate = mpa_freq_tab[sample_rate_index] >> (s->lsf + mpeg25);

  1072.     sample_rate_index += 3 * (s->lsf + mpeg25);

  1073.     s->sample_rate_index = sample_rate_index;

  1074.     s->error_protection = ((header >> 16) & 1) ^ 1;

  1075.     s->sample_rate = sample_rate;

  1076. 

  1077.     bitrate_index = (header >> 12) & 0xf;

  1078.     padding = (header >> 9) & 1;

  1079.     //extension = (header >> 8) & 1;

  1080.     s->mode = (header >> 6) & 3;

  1081.     s->mode_ext = (header >> 4) & 3;

  1082.     //copyright = (header >> 3) & 1;

  1083.     //original = (header >> 2) & 1;

  1084.     //emphasis = header & 3;

  1085. 

  1086.     if (s->mode == MPA_MONO)

  1087.         s->nb_channels = 1;

  1088.     else

  1089.         s->nb_channels = 2;

  1090.     

  1091.     if (bitrate_index != 0) {

  1092.         frame_size = mpa_bitrate_tab[s->lsf][s->layer - 1][bitrate_index];

  1093.         s->bit_rate = frame_size * 1000;

  1094.         switch(s->layer) {

  1095.         case 1:

  1096.             frame_size = (frame_size * 12000) / sample_rate;

  1097.             frame_size = (frame_size + padding) * 4;

  1098.             break;

  1099.         case 2:

  1100.             frame_size = (frame_size * 144000) / sample_rate;

  1101.             frame_size += padding;

  1102.             break;

  1103.         default:

  1104.         case 3:

  1105.             frame_size = (frame_size * 144000) / (sample_rate << s->lsf);

  1106.             frame_size += padding;

  1107.             break;

  1108.         }

  1109.         s->frame_size = frame_size;

  1110.     } else {

  1111.         /* if no frame size computed, signal it */

  1112.         if (!s->free_format_frame_size)

  1113.             return 1;

  1114.         /* free format: compute bitrate and real frame size from the

  1115.            frame size we extracted by reading the bitstream */

  1116.         s->frame_size = s->free_format_frame_size;

  1117.         switch(s->layer) {

  1118.         case 1:

  1119.             s->frame_size += padding  * 4;

  1120.             s->bit_rate = (s->frame_size * sample_rate) / 48000;

  1121.             break;

  1122.         case 2:

  1123.             s->frame_size += padding;

  1124.             s->bit_rate = (s->frame_size * sample_rate) / 144000;

  1125.             break;

  1126.         default:

  1127.         case 3:

  1128.             s->frame_size += padding;

  1129.             s->bit_rate = (s->frame_size * (sample_rate << s->lsf)) / 144000;

  1130.             break;

  1131.         }

  1132.     }

  1133.     

  1134. #if defined(DEBUG)

  1135.     printf("layer%d, %d Hz, %d kbits/s, ",

  1136.            s->layer, s->sample_rate, s->bit_rate);

  1137.     if (s->nb_channels == 2) {

  1138.         if (s->layer == 3) {

  1139.             if (s->mode_ext & MODE_EXT_MS_STEREO)

  1140.                 printf("ms-");

  1141.             if (s->mode_ext & MODE_EXT_I_STEREO)

  1142.                 printf("i-");

  1143.         }

  1144.         printf("stereo");

  1145.     } else {

  1146.         printf("mono");

  1147.     }

  1148.     printf("\n");

  1149. #endif

  1150.     return 0;

  1151. }

  1152. 

  1153. /* return the number of decoded frames */

  1154. static int mp_decode_layer1(MPADecodeContext *s)

  1155. {

  1156.     int bound, i, v, n, ch, j, mant;

  1157.     UINT8 allocation[MPA_MAX_CHANNELS][SBLIMIT];

  1158.     UINT8 scale_factors[MPA_MAX_CHANNELS][SBLIMIT];

  1159. 

  1160.     if (s->mode == MPA_JSTEREO) 

  1161.         bound = (s->mode_ext + 1) * 4;

  1162.     else

  1163.         bound = SBLIMIT;

  1164. 

  1165.     /* allocation bits */

  1166.     for(i=0;i<bound;i++) {

  1167.         for(ch=0;ch<s->nb_channels;ch++) {

  1168.             allocation[ch][i] = get_bits(&s->gb, 4);

  1169.         }

  1170.     }

  1171.     for(i=bound;i<SBLIMIT;i++) {

  1172.         allocation[0][i] = get_bits(&s->gb, 4);

  1173.     }

  1174. 

  1175.     /* scale factors */

  1176.     for(i=0;i<bound;i++) {

  1177.         for(ch=0;ch<s->nb_channels;ch++) {

  1178.             if (allocation[ch][i])

  1179.                 scale_factors[ch][i] = get_bits(&s->gb, 6);

  1180.         }

  1181.     }

  1182.     for(i=bound;i<SBLIMIT;i++) {

  1183.         if (allocation[0][i]) {

  1184.             scale_factors[0][i] = get_bits(&s->gb, 6);

  1185.             scale_factors[1][i] = get_bits(&s->gb, 6);

  1186.         }

  1187.     }

  1188.     

  1189.     /* compute samples */

  1190.     for(j=0;j<12;j++) {

  1191.         for(i=0;i<bound;i++) {

  1192.             for(ch=0;ch<s->nb_channels;ch++) {

  1193.                 n = allocation[ch][i];

  1194.                 if (n) {

  1195.                     mant = get_bits(&s->gb, n + 1);

  1196.                     v = l1_unscale(n, mant, scale_factors[ch][i]);

  1197.                 } else {

  1198.                     v = 0;

  1199.                 }

  1200.                 s->sb_samples[ch][j][i] = v;

  1201.             }

  1202.         }

  1203.         for(i=bound;i<SBLIMIT;i++) {

  1204.             n = allocation[0][i];

  1205.             if (n) {

  1206.                 mant = get_bits(&s->gb, n + 1);

  1207.                 v = l1_unscale(n, mant, scale_factors[0][i]);

  1208.                 s->sb_samples[0][j][i] = v;

  1209.                 v = l1_unscale(n, mant, scale_factors[1][i]);

  1210.                 s->sb_samples[1][j][i] = v;

  1211.             } else {

  1212.                 s->sb_samples[0][j][i] = 0;

  1213.                 s->sb_samples[1][j][i] = 0;

  1214.             }

  1215.         }

  1216.     }

  1217.     return 12;

  1218. }

  1219. 

  1220. /* bitrate is in kb/s */

  1221. int l2_select_table(int bitrate, int nb_channels, int freq, int lsf)

  1222. {

  1223.     int ch_bitrate, table;

  1224.     

  1225.     ch_bitrate = bitrate / nb_channels;

  1226.     if (!lsf) {

  1227.         if ((freq == 48000 && ch_bitrate >= 56) ||

  1228.             (ch_bitrate >= 56 && ch_bitrate <= 80)) 

  1229.             table = 0;

  1230.         else if (freq != 48000 && ch_bitrate >= 96) 

  1231.             table = 1;

  1232.         else if (freq != 32000 && ch_bitrate <= 48) 

  1233.             table = 2;

  1234.         else 

  1235.             table = 3;

  1236.     } else {

  1237.         table = 4;

  1238.     }

  1239.     return table;

  1240. }

  1241. 

  1242. static int mp_decode_layer2(MPADecodeContext *s)

  1243. {

  1244.     int sblimit; /* number of used subbands */

  1245.     const unsigned char *alloc_table;

  1246.     int table, bit_alloc_bits, i, j, ch, bound, v;

  1247.     unsigned char bit_alloc[MPA_MAX_CHANNELS][SBLIMIT];

  1248.     unsigned char scale_code[MPA_MAX_CHANNELS][SBLIMIT];

  1249.     unsigned char scale_factors[MPA_MAX_CHANNELS][SBLIMIT][3], *sf;

  1250.     int scale, qindex, bits, steps, k, l, m, b;

  1251. 

  1252.     /* select decoding table */

  1253.     table = l2_select_table(s->bit_rate / 1000, s->nb_channels, 

  1254.                             s->sample_rate, s->lsf);

  1255.     sblimit = sblimit_table[table];

  1256.     alloc_table = alloc_tables[table];

  1257. 

  1258.     if (s->mode == MPA_JSTEREO) 

  1259.         bound = (s->mode_ext + 1) * 4;

  1260.     else

  1261.         bound = sblimit;

  1262. 

  1263.     dprintf("bound=%d sblimit=%d\n", bound, sblimit);

  1264.     /* parse bit allocation */

  1265.     j = 0;

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

  1267.         bit_alloc_bits = alloc_table[j];

  1268.         for(ch=0;ch<s->nb_channels;ch++) {

  1269.             bit_alloc[ch][i] = get_bits(&s->gb, bit_alloc_bits);

  1270.         }

  1271.         j += 1 << bit_alloc_bits;

  1272.     }

  1273.     for(i=bound;i<sblimit;i++) {

  1274.         bit_alloc_bits = alloc_table[j];

  1275.         v = get_bits(&s->gb, bit_alloc_bits);

  1276.         bit_alloc[0][i] = v;

  1277.         bit_alloc[1][i] = v;

  1278.         j += 1 << bit_alloc_bits;

  1279.     }

  1280. 

  1281. #ifdef DEBUG

  1282.     {

  1283.         for(ch=0;ch<s->nb_channels;ch++) {

  1284.             for(i=0;i<sblimit;i++)

  1285.                 printf(" %d", bit_alloc[ch][i]);

  1286.             printf("\n");

  1287.         }

  1288.     }

  1289. #endif

  1290. 

  1291.     /* scale codes */

  1292.     for(i=0;i<sblimit;i++) {

  1293.         for(ch=0;ch<s->nb_channels;ch++) {

  1294.             if (bit_alloc[ch][i]) 

  1295.                 scale_code[ch][i] = get_bits(&s->gb, 2);

  1296.         }

  1297.     }

  1298.     

  1299.     /* scale factors */

  1300.     for(i=0;i<sblimit;i++) {

  1301.         for(ch=0;ch<s->nb_channels;ch++) {

  1302.             if (bit_alloc[ch][i]) {

  1303.                 sf = scale_factors[ch][i];

  1304.                 switch(scale_code[ch][i]) {

  1305.                 default:

  1306.                 case 0:

  1307.                     sf[0] = get_bits(&s->gb, 6);

  1308.                     sf[1] = get_bits(&s->gb, 6);

  1309.                     sf[2] = get_bits(&s->gb, 6);

  1310.                     break;

  1311.                 case 2:

  1312.                     sf[0] = get_bits(&s->gb, 6);

  1313.                     sf[1] = sf[0];

  1314.                     sf[2] = sf[0];

  1315.                     break;

  1316.                 case 1:

  1317.                     sf[0] = get_bits(&s->gb, 6);

  1318.                     sf[2] = get_bits(&s->gb, 6);

  1319.                     sf[1] = sf[0];

  1320.                     break;

  1321.                 case 3:

  1322.                     sf[0] = get_bits(&s->gb, 6);

  1323.                     sf[2] = get_bits(&s->gb, 6);

  1324.                     sf[1] = sf[2];

  1325.                     break;

  1326.                 }

  1327.             }

  1328.         }

  1329.     }

  1330. 

  1331. #ifdef DEBUG

  1332.     for(ch=0;ch<s->nb_channels;ch++) {

  1333.         for(i=0;i<sblimit;i++) {

  1334.             if (bit_alloc[ch][i]) {

  1335.                 sf = scale_factors[ch][i];

  1336.                 printf(" %d %d %d", sf[0], sf[1], sf[2]);

  1337.             } else {

  1338.                 printf(" -");

  1339.             }

  1340.         }

  1341.         printf("\n");

  1342.     }

  1343. #endif

  1344. 

  1345.     /* samples */

  1346.     for(k=0;k<3;k++) {

  1347.         for(l=0;l<12;l+=3) {

  1348.             j = 0;

  1349.             for(i=0;i<bound;i++) {

  1350.                 bit_alloc_bits = alloc_table[j];

  1351.                 for(ch=0;ch<s->nb_channels;ch++) {

  1352.                     b = bit_alloc[ch][i];

  1353.                     if (b) {

  1354.                         scale = scale_factors[ch][i][k];

  1355.                         qindex = alloc_table[j+b];

  1356.                         bits = quant_bits[qindex];

  1357.                         if (bits < 0) {

  1358.                             /* 3 values at the same time */

  1359.                             v = get_bits(&s->gb, -bits);

  1360.                             steps = quant_steps[qindex];

  1361.                             s->sb_samples[ch][k * 12 + l + 0][i] = 

  1362.                                 l2_unscale_group(steps, v % steps, scale);

  1363.                             v = v / steps;

  1364.                             s->sb_samples[ch][k * 12 + l + 1][i] = 

  1365.                                 l2_unscale_group(steps, v % steps, scale);

  1366.                             v = v / steps;

  1367.                             s->sb_samples[ch][k * 12 + l + 2][i] = 

  1368.                                 l2_unscale_group(steps, v, scale);

  1369.                         } else {

  1370.                             for(m=0;m<3;m++) {

  1371.                                 v = get_bits(&s->gb, bits);

  1372.                                 v = l1_unscale(bits - 1, v, scale);

  1373.                                 s->sb_samples[ch][k * 12 + l + m][i] = v;

  1374.                             }

  1375.                         }

  1376.                     } else {

  1377.                         s->sb_samples[ch][k * 12 + l + 0][i] = 0;

  1378.                         s->sb_samples[ch][k * 12 + l + 1][i] = 0;

  1379.                         s->sb_samples[ch][k * 12 + l + 2][i] = 0;

  1380.                     }

  1381.                 }

  1382.                 /* next subband in alloc table */

  1383.                 j += 1 << bit_alloc_bits; 

  1384.             }

  1385.             /* XXX: find a way to avoid this duplication of code */

  1386.             for(i=bound;i<sblimit;i++) {

  1387.                 bit_alloc_bits = alloc_table[j];

  1388.                 b = bit_alloc[0][i];

  1389.                 if (b) {

  1390.                     int mant, scale0, scale1;

  1391.                     scale0 = scale_factors[0][i][k];

  1392.                     scale1 = scale_factors[1][i][k];

  1393.                     qindex = alloc_table[j+b];

  1394.                     bits = quant_bits[qindex];

  1395.                     if (bits < 0) {

  1396.                         /* 3 values at the same time */

  1397.                         v = get_bits(&s->gb, -bits);

  1398.                         steps = quant_steps[qindex];

  1399.                         mant = v % steps;

  1400.                         v = v / steps;

  1401.                         s->sb_samples[0][k * 12 + l + 0][i] = 

  1402.                             l2_unscale_group(steps, mant, scale0);

  1403.                         s->sb_samples[1][k * 12 + l + 0][i] = 

  1404.                             l2_unscale_group(steps, mant, scale1);

  1405.                         mant = v % steps;

  1406.                         v = v / steps;

  1407.                         s->sb_samples[0][k * 12 + l + 1][i] = 

  1408.                             l2_unscale_group(steps, mant, scale0);

  1409.                         s->sb_samples[1][k * 12 + l + 1][i] = 

  1410.                             l2_unscale_group(steps, mant, scale1);

  1411.                         s->sb_samples[0][k * 12 + l + 2][i] = 

  1412.                             l2_unscale_group(steps, v, scale0);

  1413.                         s->sb_samples[1][k * 12 + l + 2][i] = 

  1414.                             l2_unscale_group(steps, v, scale1);

  1415.                     } else {

  1416.                         for(m=0;m<3;m++) {

  1417.                             mant = get_bits(&s->gb, bits);

  1418.                             s->sb_samples[0][k * 12 + l + m][i] = 

  1419.                                 l1_unscale(bits - 1, mant, scale0);

  1420.                             s->sb_samples[1][k * 12 + l + m][i] = 

  1421.                                 l1_unscale(bits - 1, mant, scale1);

  1422.                         }

  1423.                     }

  1424.                 } else {

  1425.                     s->sb_samples[0][k * 12 + l + 0][i] = 0;

  1426.                     s->sb_samples[0][k * 12 + l + 1][i] = 0;

  1427.                     s->sb_samples[0][k * 12 + l + 2][i] = 0;

  1428.                     s->sb_samples[1][k * 12 + l + 0][i] = 0;

  1429.                     s->sb_samples[1][k * 12 + l + 1][i] = 0;

  1430.                     s->sb_samples[1][k * 12 + l + 2][i] = 0;

  1431.                 }

  1432.                 /* next subband in alloc table */

  1433.                 j += 1 << bit_alloc_bits; 

  1434.             }

  1435.             /* fill remaining samples to zero */

  1436.             for(i=sblimit;i<SBLIMIT;i++) {

  1437.                 for(ch=0;ch<s->nb_channels;ch++) {

  1438.                     s->sb_samples[ch][k * 12 + l + 0][i] = 0;

  1439.                     s->sb_samples[ch][k * 12 + l + 1][i] = 0;

  1440.                     s->sb_samples[ch][k * 12 + l + 2][i] = 0;

  1441.                 }

  1442.             }

  1443.         }

  1444.     }

  1445.     return 3 * 12;

  1446. }

  1447. 

  1448. /*

  1449.  * Seek back in the stream for backstep bytes (at most 511 bytes)

  1450.  */

  1451. static void seek_to_maindata(MPADecodeContext *s, long backstep)

  1452. {

  1453.     UINT8 *ptr;

  1454. 

  1455.     /* compute current position in stream */

  1456.     ptr = s->gb.buffer + (get_bits_count(&s->gb)>>3);

  1457. 

  1458.     /* copy old data before current one */

  1459.     ptr -= backstep;

  1460.     memcpy(ptr, s->inbuf1[s->inbuf_index ^ 1] + 

  1461.            BACKSTEP_SIZE + s->old_frame_size - backstep, backstep);

  1462.     /* init get bits again */

  1463.     init_get_bits(&s->gb, ptr, s->frame_size + backstep);

  1464. 

  1465.     /* prepare next buffer */

  1466.     s->inbuf_index ^= 1;

  1467.     s->inbuf = &s->inbuf1[s->inbuf_index][BACKSTEP_SIZE];

  1468.     s->old_frame_size = s->frame_size;

  1469. }

  1470. 

  1471. static inline void lsf_sf_expand(int *slen,

  1472.                                  int sf, int n1, int n2, int n3)

  1473. {

  1474.     if (n3) {

  1475.         slen[3] = sf % n3;

  1476.         sf /= n3;

  1477.     } else {

  1478.         slen[3] = 0;

  1479.     }

  1480.     if (n2) {

  1481.         slen[2] = sf % n2;

  1482.         sf /= n2;

  1483.     } else {

  1484.         slen[2] = 0;

  1485.     }

  1486.     slen[1] = sf % n1;

  1487.     sf /= n1;

  1488.     slen[0] = sf;

  1489. }

  1490. 

  1491. static void exponents_from_scale_factors(MPADecodeContext *s, 

  1492.                                          GranuleDef *g,

  1493.                                          INT16 *exponents)

  1494. {

  1495.     const UINT8 *bstab, *pretab;

  1496.     int len, i, j, k, l, v0, shift, gain, gains[3];

  1497.     INT16 *exp_ptr;

  1498. 

  1499.     exp_ptr = exponents;

  1500.     gain = g->global_gain - 210;

  1501.     shift = g->scalefac_scale + 1;

  1502. 

  1503.     bstab = band_size_long[s->sample_rate_index];

  1504.     pretab = mpa_pretab[g->preflag];

  1505.     for(i=0;i<g->long_end;i++) {

  1506.         v0 = gain - ((g->scale_factors[i] + pretab[i]) << shift);

  1507.         len = bstab[i];

  1508.         for(j=len;j>0;j--)

  1509.             *exp_ptr++ = v0;

  1510.     }

  1511. 

  1512.     if (g->short_start < 13) {

  1513.         bstab = band_size_short[s->sample_rate_index];

  1514.         gains[0] = gain - (g->subblock_gain[0] << 3);

  1515.         gains[1] = gain - (g->subblock_gain[1] << 3);

  1516.         gains[2] = gain - (g->subblock_gain[2] << 3);

  1517.         k = g->long_end;

  1518.         for(i=g->short_start;i<13;i++) {

  1519.             len = bstab[i];

  1520.             for(l=0;l<3;l++) {

  1521.                 v0 = gains[l] - (g->scale_factors[k++] << shift);

  1522.                 for(j=len;j>0;j--)

  1523.                 *exp_ptr++ = v0;

  1524.             }

  1525.         }

  1526.     }

  1527. }

  1528. 

  1529. /* handle n = 0 too */

  1530. static inline int get_bitsz(GetBitContext *s, int n)

  1531. {

  1532.     if (n == 0)

  1533.         return 0;

  1534.     else

  1535.         return get_bits(s, n);

  1536. }

  1537. 

  1538. static int huffman_decode(MPADecodeContext *s, GranuleDef *g,

  1539.                           INT16 *exponents, int end_pos)

  1540. {

  1541.     int s_index;

  1542.     int linbits, code, x, y, l, v, i, j, k, pos;

  1543.     GetBitContext last_gb;

  1544.     VLC *vlc;

  1545.     UINT8 *code_table;

  1546. 

  1547.     /* low frequencies (called big values) */

  1548.     s_index = 0;

  1549.     for(i=0;i<3;i++) {

  1550.         j = g->region_size[i];

  1551.         if (j == 0)

  1552.             continue;

  1553.         /* select vlc table */

  1554.         k = g->table_select[i];

  1555.         l = mpa_huff_data[k][0];

  1556.         linbits = mpa_huff_data[k][1];

  1557.         vlc = &huff_vlc[l];

  1558.         code_table = huff_code_table[l];

  1559. 

  1560.         /* read huffcode and compute each couple */

  1561.         for(;j>0;j--) {

  1562.             if (get_bits_count(&s->gb) >= end_pos)

  1563.                 break;

  1564.             if (code_table) {

  1565.                 code = get_vlc(&s->gb, vlc);

  1566.                 if (code < 0)

  1567.                     return -1;

  1568.                 y = code_table[code];

  1569.                 x = y >> 4;

  1570.                 y = y & 0x0f;

  1571.             } else {

  1572.                 x = 0;

  1573.                 y = 0;

  1574.             }

  1575.             dprintf("region=%d n=%d x=%d y=%d exp=%d\n", 

  1576.                     i, g->region_size[i] - j, x, y, exponents[s_index]);

  1577.             if (x) {

  1578.                 if (x == 15)

  1579.                     x += get_bitsz(&s->gb, linbits);

  1580.                 v = l3_unscale(x, exponents[s_index]);

  1581.                 if (get_bits1(&s->gb))

  1582.                     v = -v;

  1583.             } else {

  1584.                 v = 0;

  1585.             }

  1586.             g->sb_hybrid[s_index++] = v;

  1587.             if (y) {

  1588.                 if (y == 15)

  1589.                     y += get_bitsz(&s->gb, linbits);

  1590.                 v = l3_unscale(y, exponents[s_index]);

  1591.                 if (get_bits1(&s->gb))

  1592.                     v = -v;

  1593.             } else {

  1594.                 v = 0;

  1595.             }

  1596.             g->sb_hybrid[s_index++] = v;

  1597.         }

  1598.     }

  1599.             

  1600.     /* high frequencies */

  1601.     vlc = &huff_quad_vlc[g->count1table_select];

  1602.     last_gb.buffer = NULL;

  1603.     while (s_index <= 572) {

  1604.         pos = get_bits_count(&s->gb);

  1605.         if (pos >= end_pos) {

  1606.             if (pos > end_pos && last_gb.buffer != NULL) {

  1607.                 /* some encoders generate an incorrect size for this

  1608.                    part. We must go back into the data */

  1609.                 s_index -= 4;

  1610.                 s->gb = last_gb;

  1611.             }

  1612.             break;

  1613.         }

  1614.         last_gb= s->gb;

  1615. 

  1616.         code = get_vlc(&s->gb, vlc);

  1617.         dprintf("t=%d code=%d\n", g->count1table_select, code);

  1618.         if (code < 0)

  1619.             return -1;

  1620.         for(i=0;i<4;i++) {

  1621.             if (code & (8 >> i)) {

  1622.                 /* non zero value. Could use a hand coded function for

  1623.                    'one' value */

  1624.                 v = l3_unscale(1, exponents[s_index]);

  1625.                 if(get_bits1(&s->gb))

  1626.                     v = -v;

  1627.             } else {

  1628.                 v = 0;

  1629.             }

  1630.             g->sb_hybrid[s_index++] = v;

  1631.         }

  1632.     }

  1633.     while (s_index < 576)

  1634.         g->sb_hybrid[s_index++] = 0;

  1635.     return 0;

  1636. }

  1637. 

  1638. /* Reorder short blocks from bitstream order to interleaved order. It

  1639.    would be faster to do it in parsing, but the code would be far more

  1640.    complicated */

  1641. static void reorder_block(MPADecodeContext *s, GranuleDef *g)

  1642. {

  1643.     int i, j, k, len;

  1644.     INT32 *ptr, *dst, *ptr1;

  1645.     INT32 tmp[576];

  1646. 

  1647.     if (g->block_type != 2)

  1648.         return;

  1649. 

  1650.     if (g->switch_point) {

  1651.         if (s->sample_rate_index != 8) {

  1652.             ptr = g->sb_hybrid + 36;

  1653.         } else {

  1654.             ptr = g->sb_hybrid + 48;

  1655.         }

  1656.     } else {

  1657.         ptr = g->sb_hybrid;

  1658.     }

  1659.     

  1660.     for(i=g->short_start;i<13;i++) {

  1661.         len = band_size_short[s->sample_rate_index][i];

  1662.         ptr1 = ptr;

  1663.         for(k=0;k<3;k++) {

  1664.             dst = tmp + k;

  1665.             for(j=len;j>0;j--) {

  1666.                 *dst = *ptr++;

  1667.                 dst += 3;

  1668.             }

  1669.         }

  1670.         memcpy(ptr1, tmp, len * 3 * sizeof(INT32));

  1671.     }

  1672. }

  1673. 

  1674. #define ISQRT2 FIXR(0.70710678118654752440)

  1675. 

  1676. static void compute_stereo(MPADecodeContext *s,

  1677.                            GranuleDef *g0, GranuleDef *g1)

  1678. {

  1679.     int i, j, k, l;

  1680.     INT32 v1, v2;

  1681.     int sf_max, tmp0, tmp1, sf, len, non_zero_found;

  1682.     INT32 (*is_tab)[16];

  1683.     INT32 *tab0, *tab1;

  1684.     int non_zero_found_short[3];

  1685. 

  1686.     /* intensity stereo */

  1687.     if (s->mode_ext & MODE_EXT_I_STEREO) {

  1688.         if (!s->lsf) {

  1689.             is_tab = is_table;

  1690.             sf_max = 7;

  1691.         } else {

  1692.             is_tab = is_table_lsf[g1->scalefac_compress & 1];

  1693.             sf_max = 16;

  1694.         }

  1695.             

  1696.         tab0 = g0->sb_hybrid + 576;

  1697.         tab1 = g1->sb_hybrid + 576;

  1698. 

  1699.         non_zero_found_short[0] = 0;

  1700.         non_zero_found_short[1] = 0;

  1701.         non_zero_found_short[2] = 0;

  1702.         k = (13 - g1->short_start) * 3 + g1->long_end - 3;

  1703.         for(i = 12;i >= g1->short_start;i--) {

  1704.             /* for last band, use previous scale factor */

  1705.             if (i != 11)

  1706.                 k -= 3;

  1707.             len = band_size_short[s->sample_rate_index][i];

  1708.             for(l=2;l>=0;l--) {

  1709.                 tab0 -= len;

  1710.                 tab1 -= len;

  1711.                 if (!non_zero_found_short[l]) {

  1712.                     /* test if non zero band. if so, stop doing i-stereo */

  1713.                     for(j=0;j<len;j++) {

  1714.                         if (tab1[j] != 0) {

  1715.                             non_zero_found_short[l] = 1;

  1716.                             goto found1;

  1717.                         }

  1718.                     }

  1719.                     sf = g1->scale_factors[k + l];

  1720.                     if (sf >= sf_max)

  1721.                         goto found1;

  1722. 

  1723.                     v1 = is_tab[0][sf];

  1724.                     v2 = is_tab[1][sf];

  1725.                     for(j=0;j<len;j++) {

  1726.                         tmp0 = tab0[j];

  1727.                         tab0[j] = MULL(tmp0, v1);

  1728.                         tab1[j] = MULL(tmp0, v2);

  1729.                     }

  1730.                 } else {

  1731.                 found1:

  1732.                     if (s->mode_ext & MODE_EXT_MS_STEREO) {

  1733.                         /* lower part of the spectrum : do ms stereo

  1734.                            if enabled */

  1735.                         for(j=0;j<len;j++) {

  1736.                             tmp0 = tab0[j];

  1737.                             tmp1 = tab1[j];

  1738.                             tab0[j] = MULL(tmp0 + tmp1, ISQRT2);

  1739.                             tab1[j] = MULL(tmp0 - tmp1, ISQRT2);

  1740.                         }

  1741.                     }

  1742.                 }

  1743.             }

  1744.         }

  1745. 

  1746.         non_zero_found = non_zero_found_short[0] | 

  1747.             non_zero_found_short[1] | 

  1748.             non_zero_found_short[2];

  1749. 

  1750.         for(i = g1->long_end - 1;i >= 0;i--) {

  1751.             len = band_size_long[s->sample_rate_index][i];

  1752.             tab0 -= len;

  1753.             tab1 -= len;

  1754.             /* test if non zero band. if so, stop doing i-stereo */

  1755.             if (!non_zero_found) {

  1756.                 for(j=0;j<len;j++) {

  1757.                     if (tab1[j] != 0) {

  1758.                         non_zero_found = 1;

  1759.                         goto found2;

  1760.                     }

  1761.                 }

  1762.                 /* for last band, use previous scale factor */

  1763.                 k = (i == 21) ? 20 : i;

  1764.                 sf = g1->scale_factors[k];

  1765.                 if (sf >= sf_max)

  1766.                     goto found2;

  1767.                 v1 = is_tab[0][sf];

  1768.                 v2 = is_tab[1][sf];

  1769.                 for(j=0;j<len;j++) {

  1770.                     tmp0 = tab0[j];

  1771.                     tab0[j] = MULL(tmp0, v1);

  1772.                     tab1[j] = MULL(tmp0, v2);

  1773.                 }

  1774.             } else {

  1775.             found2:

  1776.                 if (s->mode_ext & MODE_EXT_MS_STEREO) {

  1777.                     /* lower part of the spectrum : do ms stereo

  1778.                        if enabled */

  1779.                     for(j=0;j<len;j++) {

  1780.                         tmp0 = tab0[j];

  1781.                         tmp1 = tab1[j];

  1782.                         tab0[j] = MULL(tmp0 + tmp1, ISQRT2);

  1783.                         tab1[j] = MULL(tmp0 - tmp1, ISQRT2);

  1784.                     }

  1785.                 }

  1786.             }

  1787.         }

  1788.     } else if (s->mode_ext & MODE_EXT_MS_STEREO) {

  1789.         /* ms stereo ONLY */

  1790.         /* NOTE: the 1/sqrt(2) normalization factor is included in the

  1791.            global gain */

  1792.         tab0 = g0->sb_hybrid;

  1793.         tab1 = g1->sb_hybrid;

  1794.         for(i=0;i<576;i++) {

  1795.             tmp0 = tab0[i];

  1796.             tmp1 = tab1[i];

  1797.             tab0[i] = tmp0 + tmp1;

  1798.             tab1[i] = tmp0 - tmp1;

  1799.         }

  1800.     }

  1801. }

  1802. 

  1803. static void compute_antialias(MPADecodeContext *s,

  1804.                               GranuleDef *g)

  1805. {

  1806.     INT32 *ptr, *p0, *p1, *csa;

  1807.     int n, tmp0, tmp1, i, j;

  1808. 

  1809.     /* we antialias only "long" bands */

  1810.     if (g->block_type == 2) {

  1811.         if (!g->switch_point)

  1812.             return;

  1813.         /* XXX: check this for 8000Hz case */

  1814.         n = 1;

  1815.     } else {

  1816.         n = SBLIMIT - 1;

  1817.     }

  1818.     

  1819.     ptr = g->sb_hybrid + 18;

  1820.     for(i = n;i > 0;i--) {

  1821.         p0 = ptr - 1;

  1822.         p1 = ptr;

  1823.         csa = &csa_table[0][0];

  1824.         for(j=0;j<8;j++) {

  1825.             tmp0 = *p0;

  1826.             tmp1 = *p1;

  1827.             *p0 = FRAC_RND(MUL64(tmp0, csa[0]) - MUL64(tmp1, csa[1]));

  1828.             *p1 = FRAC_RND(MUL64(tmp0, csa[1]) + MUL64(tmp1, csa[0]));

  1829.             p0--;

  1830.             p1++;

  1831.             csa += 2;

  1832.         }

  1833.         ptr += 18;

  1834.     }

  1835. }

  1836. 

  1837. static void compute_imdct(MPADecodeContext *s,

  1838.                           GranuleDef *g, 

  1839.                           INT32 *sb_samples,

  1840.                           INT32 *mdct_buf)

  1841. {

  1842.     INT32 *ptr, *win, *win1, *buf, *buf2, *out_ptr, *ptr1;

  1843.     INT32 in[6];

  1844.     INT32 out[36];

  1845.     INT32 out2[12];

  1846.     int i, j, k, mdct_long_end, v, sblimit;

  1847. 

  1848.     /* find last non zero block */

  1849.     ptr = g->sb_hybrid + 576;

  1850.     ptr1 = g->sb_hybrid + 2 * 18;

  1851.     while (ptr >= ptr1) {

  1852.         ptr -= 6;

  1853.         v = ptr[0] | ptr[1] | ptr[2] | ptr[3] | ptr[4] | ptr[5];

  1854.         if (v != 0)

  1855.             break;

  1856.     }

  1857.     sblimit = ((ptr - g->sb_hybrid) / 18) + 1;

  1858. 

  1859.     if (g->block_type == 2) {

  1860.         /* XXX: check for 8000 Hz */

  1861.         if (g->switch_point)

  1862.             mdct_long_end = 2;

  1863.         else

  1864.             mdct_long_end = 0;

  1865.     } else {

  1866.         mdct_long_end = sblimit;

  1867.     }

  1868. 

  1869.     buf = mdct_buf;

  1870.     ptr = g->sb_hybrid;

  1871.     for(j=0;j<mdct_long_end;j++) {

  1872.         imdct36(out, ptr);

  1873.         /* apply window & overlap with previous buffer */

  1874.         out_ptr = sb_samples + j;

  1875.         /* select window */

  1876.         if (g->switch_point && j < 2)

  1877.             win1 = mdct_win[0];

  1878.         else

  1879.             win1 = mdct_win[g->block_type];

  1880.         /* select frequency inversion */

  1881.         win = win1 + ((4 * 36) & -(j & 1));

  1882.         for(i=0;i<18;i++) {

  1883.             *out_ptr = MULL(out[i], win[i]) + buf[i];

  1884.             buf[i] = MULL(out[i + 18], win[i + 18]);

  1885.             out_ptr += SBLIMIT;

  1886.         }

  1887.         ptr += 18;

  1888.         buf += 18;

  1889.     }

  1890.     for(j=mdct_long_end;j<sblimit;j++) {

  1891.         for(i=0;i<6;i++) {

  1892.             out[i] = 0;

  1893.             out[6 + i] = 0;

  1894.             out[30+i] = 0;

  1895.         }

  1896.         /* select frequency inversion */

  1897.         win = mdct_win[2] + ((4 * 36) & -(j & 1));

  1898.         buf2 = out + 6;

  1899.         for(k=0;k<3;k++) {

  1900.             /* reorder input for short mdct */

  1901.             ptr1 = ptr + k;

  1902.             for(i=0;i<6;i++) {

  1903.                 in[i] = *ptr1;

  1904.                 ptr1 += 3;

  1905.             }

  1906.             imdct12(out2, in);

  1907.             /* apply 12 point window and do small overlap */

  1908.             for(i=0;i<6;i++) {

  1909.                 buf2[i] = MULL(out2[i], win[i]) + buf2[i];

  1910.                 buf2[i + 6] = MULL(out2[i + 6], win[i + 6]);

  1911.             }

  1912.             buf2 += 6;

  1913.         }

  1914.         /* overlap */

  1915.         out_ptr = sb_samples + j;

  1916.         for(i=0;i<18;i++) {

  1917.             *out_ptr = out[i] + buf[i];

  1918.             buf[i] = out[i + 18];

  1919.             out_ptr += SBLIMIT;

  1920.         }

  1921.         ptr += 18;

  1922.         buf += 18;

  1923.     }

  1924.     /* zero bands */

  1925.     for(j=sblimit;j<SBLIMIT;j++) {

  1926.         /* overlap */

  1927.         out_ptr = sb_samples + j;

  1928.         for(i=0;i<18;i++) {

  1929.             *out_ptr = buf[i];

  1930.             buf[i] = 0;

  1931.             out_ptr += SBLIMIT;

  1932.         }

  1933.         buf += 18;

  1934.     }

  1935. }

  1936. 

  1937. #if defined(DEBUG)

  1938. void sample_dump(int fnum, INT32 *tab, int n)

  1939. {

  1940.     static FILE *files[16], *f;

  1941.     char buf[512];

  1942.     int i;

  1943.     INT32 v;

  1944.     

  1945.     f = files[fnum];

  1946.     if (!f) {

  1947.         sprintf(buf, "/tmp/out%d.%s.pcm", 

  1948.                 fnum, 

  1949. #ifdef USE_HIGHPRECISION

  1950.                 "hp"

  1951. #else

  1952.                 "lp"

  1953. #endif

  1954.                 );

  1955.         f = fopen(buf, "w");

  1956.         if (!f)

  1957.             return;

  1958.         files[fnum] = f;

  1959.     }

  1960.     

  1961.     if (fnum == 0) {

  1962.         static int pos = 0;

  1963.         printf("pos=%d\n", pos);

  1964.         for(i=0;i<n;i++) {

  1965.             printf(" %0.4f", (double)tab[i] / FRAC_ONE);

  1966.             if ((i % 18) == 17)

  1967.                 printf("\n");

  1968.         }

  1969.         pos += n;

  1970.     }

  1971.     for(i=0;i<n;i++) {

  1972.         /* normalize to 23 frac bits */

  1973.         v = tab[i] << (23 - FRAC_BITS);

  1974.         fwrite(&v, 1, sizeof(INT32), f);

  1975.     }

  1976. }

  1977. #endif

  1978. 

  1979. 

  1980. /* main layer3 decoding function */

  1981. static int mp_decode_layer3(MPADecodeContext *s)

  1982. {

  1983.     int nb_granules, main_data_begin, private_bits;

  1984.     int gr, ch, blocksplit_flag, i, j, k, n, bits_pos, bits_left;

  1985.     GranuleDef granules[2][2], *g;

  1986.     INT16 exponents[576];

  1987. 

  1988.     /* read side info */

  1989.     if (s->lsf) {

  1990.         main_data_begin = get_bits(&s->gb, 8);

  1991.         if (s->nb_channels == 2)

  1992.             private_bits = get_bits(&s->gb, 2);

  1993.         else

  1994.             private_bits = get_bits(&s->gb, 1);

  1995.         nb_granules = 1;

  1996.     } else {

  1997.         main_data_begin = get_bits(&s->gb, 9);

  1998.         if (s->nb_channels == 2)

  1999.             private_bits = get_bits(&s->gb, 3);

  2000.         else

  2001.             private_bits = get_bits(&s->gb, 5);

  2002.         nb_granules = 2;

  2003.         for(ch=0;ch<s->nb_channels;ch++) {

  2004.             granules[ch][0].scfsi = 0; /* all scale factors are transmitted */

  2005.             granules[ch][1].scfsi = get_bits(&s->gb, 4);

  2006.         }

  2007.     }

  2008.     

  2009.     for(gr=0;gr<nb_granules;gr++) {

  2010.         for(ch=0;ch<s->nb_channels;ch++) {

  2011.             dprintf("gr=%d ch=%d: side_info\n", gr, ch);

  2012.             g = &granules[ch][gr];

  2013.             g->part2_3_length = get_bits(&s->gb, 12);

  2014.             g->big_values = get_bits(&s->gb, 9);

  2015.             g->global_gain = get_bits(&s->gb, 8);

  2016.             /* if MS stereo only is selected, we precompute the

  2017.                1/sqrt(2) renormalization factor */

  2018.             if ((s->mode_ext & (MODE_EXT_MS_STEREO | MODE_EXT_I_STEREO)) == 

  2019.                 MODE_EXT_MS_STEREO)

  2020.                 g->global_gain -= 2;

  2021.             if (s->lsf)

  2022.                 g->scalefac_compress = get_bits(&s->gb, 9);

  2023.             else

  2024.                 g->scalefac_compress = get_bits(&s->gb, 4);

  2025.             blocksplit_flag = get_bits(&s->gb, 1);

  2026.             if (blocksplit_flag) {

  2027.                 g->block_type = get_bits(&s->gb, 2);

  2028.                 if (g->block_type == 0)

  2029.                     return -1;

  2030.                 g->switch_point = get_bits(&s->gb, 1);

  2031.                 for(i=0;i<2;i++)

  2032.                     g->table_select[i] = get_bits(&s->gb, 5);

  2033.                 for(i=0;i<3;i++) 

  2034.                     g->subblock_gain[i] = get_bits(&s->gb, 3);

  2035.                 /* compute huffman coded region sizes */

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

  2037.                     g->region_size[0] = (36 / 2);

  2038.                 else {

  2039.                     if (s->sample_rate_index <= 2) 

  2040.                         g->region_size[0] = (36 / 2);

  2041.                     else if (s->sample_rate_index != 8) 

  2042.                         g->region_size[0] = (54 / 2);

  2043.                     else

  2044.                         g->region_size[0] = (108 / 2);

  2045.                 }

  2046.                 g->region_size[1] = (576 / 2);

  2047.             } else {

  2048.                 int region_address1, region_address2, l;

  2049.                 g->block_type = 0;

  2050.                 g->switch_point = 0;

  2051.                 for(i=0;i<3;i++)

  2052.                     g->table_select[i] = get_bits(&s->gb, 5);

  2053.                 /* compute huffman coded region sizes */

  2054.                 region_address1 = get_bits(&s->gb, 4);

  2055.                 region_address2 = get_bits(&s->gb, 3);

  2056.                 dprintf("region1=%d region2=%d\n", 

  2057.                         region_address1, region_address2);

  2058.                 g->region_size[0] = 

  2059.                     band_index_long[s->sample_rate_index][region_address1 + 1] >> 1;

  2060.                 l = region_address1 + region_address2 + 2;

  2061.                 /* should not overflow */

  2062.                 if (l > 22)

  2063.                     l = 22;

  2064.                 g->region_size[1] = 

  2065.                     band_index_long[s->sample_rate_index][l] >> 1;

  2066.             }

  2067.             /* convert region offsets to region sizes and truncate

  2068.                size to big_values */

  2069.             g->region_size[2] = (576 / 2);

  2070.             j = 0;

  2071.             for(i=0;i<3;i++) {

  2072.                 k = g->region_size[i];

  2073.                 if (k > g->big_values)

  2074.                     k = g->big_values;

  2075.                 g->region_size[i] = k - j;

  2076.                 j = k;

  2077.             }

  2078. 

  2079.             /* compute band indexes */

  2080.             if (g->block_type == 2) {

  2081.                 if (g->switch_point) {

  2082.                     /* if switched mode, we handle the 36 first samples as

  2083.                        long blocks.  For 8000Hz, we handle the 48 first

  2084.                        exponents as long blocks (XXX: check this!) */

  2085.                     if (s->sample_rate_index <= 2)

  2086.                         g->long_end = 8;

  2087.                     else if (s->sample_rate_index != 8)

  2088.                         g->long_end = 6;

  2089.                     else

  2090.                         g->long_end = 4; /* 8000 Hz */

  2091.                     

  2092.                     if (s->sample_rate_index != 8)

  2093.                         g->short_start = 3;

  2094.                     else

  2095.                         g->short_start = 2; 

  2096.                 } else {

  2097.                     g->long_end = 0;

  2098.                     g->short_start = 0;

  2099.                 }

  2100.             } else {

  2101.                 g->short_start = 13;

  2102.                 g->long_end = 22;

  2103.             }

  2104.             

  2105.             g->preflag = 0;

  2106.             if (!s->lsf)

  2107.                 g->preflag = get_bits(&s->gb, 1);

  2108.             g->scalefac_scale = get_bits(&s->gb, 1);

  2109.             g->count1table_select = get_bits(&s->gb, 1);

  2110.             dprintf("block_type=%d switch_point=%d\n",

  2111.                     g->block_type, g->switch_point);

  2112.         }

  2113.     }

  2114. 

  2115.     /* now we get bits from the main_data_begin offset */

  2116.     dprintf("seekback: %d\n", main_data_begin);

  2117.     seek_to_maindata(s, main_data_begin);

  2118. 

  2119.     for(gr=0;gr<nb_granules;gr++) {

  2120.         for(ch=0;ch<s->nb_channels;ch++) {

  2121.             g = &granules[ch][gr];

  2122.             

  2123.             bits_pos = get_bits_count(&s->gb);

  2124.             

  2125.             if (!s->lsf) {

  2126.                 UINT8 *sc;

  2127.                 int slen, slen1, slen2;

  2128. 

  2129.                 /* MPEG1 scale factors */

  2130.                 slen1 = slen_table[0][g->scalefac_compress];

  2131.                 slen2 = slen_table[1][g->scalefac_compress];

  2132.                 dprintf("slen1=%d slen2=%d\n", slen1, slen2);

  2133.                 if (g->block_type == 2) {

  2134.                     n = g->switch_point ? 17 : 18;

  2135.                     j = 0;

  2136.                     for(i=0;i<n;i++)

  2137.                         g->scale_factors[j++] = get_bitsz(&s->gb, slen1);

  2138.                     for(i=0;i<18;i++)

  2139.                         g->scale_factors[j++] = get_bitsz(&s->gb, slen2);

  2140.                     for(i=0;i<3;i++)

  2141.                         g->scale_factors[j++] = 0;

  2142.                 } else {

  2143.                     sc = granules[ch][0].scale_factors;

  2144.                     j = 0;

  2145.                     for(k=0;k<4;k++) {

  2146.                         n = (k == 0 ? 6 : 5);

  2147.                         if ((g->scfsi & (0x8 >> k)) == 0) {

  2148.                             slen = (k < 2) ? slen1 : slen2;

  2149.                             for(i=0;i<n;i++)

  2150.                                 g->scale_factors[j++] = get_bitsz(&s->gb, slen);

  2151.                         } else {

  2152.                             /* simply copy from last granule */

  2153.                             for(i=0;i<n;i++) {

  2154.                                 g->scale_factors[j] = sc[j];

  2155.                                 j++;

  2156.                             }

  2157.                         }

  2158.                     }

  2159.                     g->scale_factors[j++] = 0;

  2160.                 }

  2161. #if defined(DEBUG)

  2162.                 {

  2163.                     printf("scfsi=%x gr=%d ch=%d scale_factors:\n", 

  2164.                            g->scfsi, gr, ch);

  2165.                     for(i=0;i<j;i++)

  2166.                         printf(" %d", g->scale_factors[i]);

  2167.                     printf("\n");

  2168.                 }

  2169. #endif

  2170.             } else {

  2171.                 int tindex, tindex2, slen[4], sl, sf;

  2172. 

  2173.                 /* LSF scale factors */

  2174.                 if (g->block_type == 2) {

  2175.                     tindex = g->switch_point ? 2 : 1;

  2176.                 } else {

  2177.                     tindex = 0;

  2178.                 }

  2179.                 sf = g->scalefac_compress;

  2180.                 if ((s->mode_ext & MODE_EXT_I_STEREO) && ch == 1) {

  2181.                     /* intensity stereo case */

  2182.                     sf >>= 1;

  2183.                     if (sf < 180) {

  2184.                         lsf_sf_expand(slen, sf, 6, 6, 0);

  2185.                         tindex2 = 3;

  2186.                     } else if (sf < 244) {

  2187.                         lsf_sf_expand(slen, sf - 180, 4, 4, 0);

  2188.                         tindex2 = 4;

  2189.                     } else {

  2190.                         lsf_sf_expand(slen, sf - 244, 3, 0, 0);

  2191.                         tindex2 = 5;

  2192.                     }

  2193.                 } else {

  2194.                     /* normal case */

  2195.                     if (sf < 400) {

  2196.                         lsf_sf_expand(slen, sf, 5, 4, 4);

  2197.                         tindex2 = 0;

  2198.                     } else if (sf < 500) {

  2199.                         lsf_sf_expand(slen, sf - 400, 5, 4, 0);

  2200.                         tindex2 = 1;

  2201.                     } else {

  2202.                         lsf_sf_expand(slen, sf - 500, 3, 0, 0);

  2203.                         tindex2 = 2;

  2204.                         g->preflag = 1;

  2205.                     }

  2206.                 }

  2207. 

  2208.                 j = 0;

  2209.                 for(k=0;k<4;k++) {

  2210.                     n = lsf_nsf_table[tindex2][tindex][k];

  2211.                     sl = slen[k];

  2212.                     for(i=0;i<n;i++)

  2213.                         g->scale_factors[j++] = get_bitsz(&s->gb, sl);

  2214.                 }

  2215.                 /* XXX: should compute exact size */

  2216.                 for(;j<40;j++)

  2217.                     g->scale_factors[j] = 0;

  2218. #if defined(DEBUG)

  2219.                 {

  2220.                     printf("gr=%d ch=%d scale_factors:\n", 

  2221.                            gr, ch);

  2222.                     for(i=0;i<40;i++)

  2223.                         printf(" %d", g->scale_factors[i]);

  2224.                     printf("\n");

  2225.                 }

  2226. #endif

  2227.             }

  2228. 

  2229.             exponents_from_scale_factors(s, g, exponents);

  2230. 

  2231.             /* read Huffman coded residue */

  2232.             if (huffman_decode(s, g, exponents,

  2233.                                bits_pos + g->part2_3_length) < 0)

  2234.                 return -1;

  2235. #if defined(DEBUG)

  2236.             sample_dump(0, g->sb_hybrid, 576);

  2237. #endif

  2238. 

  2239.             /* skip extension bits */

  2240.             bits_left = g->part2_3_length - (get_bits_count(&s->gb) - bits_pos);

  2241.             if (bits_left < 0) {

  2242.                 dprintf("bits_left=%d\n", bits_left);

  2243.                 return -1;

  2244.             }

  2245.             while (bits_left >= 16) {

  2246.                 skip_bits(&s->gb, 16);

  2247.                 bits_left -= 16;

  2248.             }

  2249.             if (bits_left > 0)

  2250.                 skip_bits(&s->gb, bits_left);

  2251.         } /* ch */

  2252. 

  2253.         if (s->nb_channels == 2)

  2254.             compute_stereo(s, &granules[0][gr], &granules[1][gr]);

  2255. 

  2256.         for(ch=0;ch<s->nb_channels;ch++) {

  2257.             g = &granules[ch][gr];

  2258. 

  2259.             reorder_block(s, g);

  2260. #if defined(DEBUG)

  2261.             sample_dump(0, g->sb_hybrid, 576);

  2262. #endif

  2263.             compute_antialias(s, g);

  2264. #if defined(DEBUG)

  2265.             sample_dump(1, g->sb_hybrid, 576);

  2266. #endif

  2267.             compute_imdct(s, g, &s->sb_samples[ch][18 * gr][0], s->mdct_buf[ch]); 

  2268. #if defined(DEBUG)

  2269.             sample_dump(2, &s->sb_samples[ch][18 * gr][0], 576);

  2270. #endif

  2271.         }

  2272.     } /* gr */

  2273.     return nb_granules * 18;

  2274. }

  2275. 

  2276. static int mp_decode_frame(MPADecodeContext *s, 

  2277.                            short *samples)

  2278. {

  2279.     int i, nb_frames, ch;

  2280.     short *samples_ptr;

  2281. 

  2282.     init_get_bits(&s->gb, s->inbuf + HEADER_SIZE, 

  2283.                   s->inbuf_ptr - s->inbuf - HEADER_SIZE);

  2284.     

  2285.     /* skip error protection field */

  2286.     if (s->error_protection)

  2287.         get_bits(&s->gb, 16);

  2288. 

  2289.     dprintf("frame %d:\n", s->frame_count);

  2290.     switch(s->layer) {

  2291.     case 1:

  2292.         nb_frames = mp_decode_layer1(s);

  2293.         break;

  2294.     case 2:

  2295.         nb_frames = mp_decode_layer2(s);

  2296.         break;

  2297.     case 3:

  2298.     default:

  2299.         nb_frames = mp_decode_layer3(s);

  2300.         break;

  2301.     }

  2302. #if defined(DEBUG)

  2303.     for(i=0;i<nb_frames;i++) {

  2304.         for(ch=0;ch<s->nb_channels;ch++) {

  2305.             int j;

  2306.             printf("%d-%d:", i, ch);

  2307.             for(j=0;j<SBLIMIT;j++)

  2308.                 printf(" %0.6f", (double)s->sb_samples[ch][i][j] / FRAC_ONE);

  2309.             printf("\n");

  2310.         }

  2311.     }

  2312. #endif

  2313.     /* apply the synthesis filter */

  2314.     for(ch=0;ch<s->nb_channels;ch++) {

  2315.         samples_ptr = samples + ch;

  2316.         for(i=0;i<nb_frames;i++) {

  2317.             synth_filter(s, ch, samples_ptr, s->nb_channels,

  2318.                          s->sb_samples[ch][i]);

  2319.             samples_ptr += 32 * s->nb_channels;

  2320.         }

  2321.     }

  2322. #ifdef DEBUG

  2323.     s->frame_count++;        

  2324. #endif

  2325.     return nb_frames * 32 * sizeof(short) * s->nb_channels;

  2326. }

  2327. 

  2328. static int decode_frame(AVCodecContext * avctx,

  2329. 			void *data, int *data_size,

  2330. 			UINT8 * buf, int buf_size)

  2331. {

  2332.     MPADecodeContext *s = avctx->priv_data;

  2333.     UINT32 header;

  2334.     UINT8 *buf_ptr;

  2335.     int len, out_size;

  2336.     short *out_samples = data;

  2337. 

  2338.     *data_size = 0;

  2339.     buf_ptr = buf;

  2340.     while (buf_size > 0) {

  2341. 	len = s->inbuf_ptr - s->inbuf;

  2342. 	if (s->frame_size == 0) {

  2343.             /* special case for next header for first frame in free

  2344.                format case (XXX: find a simpler method) */

  2345.             if (s->free_format_next_header != 0) {

  2346.                 s->inbuf[0] = s->free_format_next_header >> 24;

  2347.                 s->inbuf[1] = s->free_format_next_header >> 16;

  2348.                 s->inbuf[2] = s->free_format_next_header >> 8;

  2349.                 s->inbuf[3] = s->free_format_next_header;

  2350.                 s->inbuf_ptr = s->inbuf + 4;

  2351.                 s->free_format_next_header = 0;

  2352.                 goto got_header;

  2353.             }

  2354. 	    /* no header seen : find one. We need at least HEADER_SIZE

  2355.                bytes to parse it */

  2356. 	    len = HEADER_SIZE - len;

  2357. 	    if (len > buf_size)

  2358. 		len = buf_size;

  2359. 	    if (len > 0) {

  2360. 		memcpy(s->inbuf_ptr, buf_ptr, len);

  2361. 		buf_ptr += len;

  2362. 		buf_size -= len;

  2363. 		s->inbuf_ptr += len;

  2364. 	    }

  2365. 	    if ((s->inbuf_ptr - s->inbuf) >= HEADER_SIZE) {

  2366.             got_header:

  2367. 		header = (s->inbuf[0] << 24) | (s->inbuf[1] << 16) |

  2368. 		    (s->inbuf[2] << 8) | s->inbuf[3];

  2369. 

  2370. 		if (check_header(header) < 0) {

  2371. 		    /* no sync found : move by one byte (inefficient, but simple!) */

  2372. 		    memcpy(s->inbuf, s->inbuf + 1, s->inbuf_ptr - s->inbuf - 1);

  2373. 		    s->inbuf_ptr--;

  2374.                     dprintf("skip %x\n", header);

  2375.                     /* reset free format frame size to give a chance

  2376.                        to get a new bitrate */

  2377.                     s->free_format_frame_size = 0;

  2378. 		} else {

  2379. 		    if (decode_header(s, header) == 1) {

  2380.                         /* free format: prepare to compute frame size */

  2381. 			s->frame_size = -1;

  2382.                     }

  2383.                     /* update codec info */

  2384.                     avctx->sample_rate = s->sample_rate;

  2385.                     avctx->channels = s->nb_channels;

  2386.                     avctx->bit_rate = s->bit_rate;

  2387.                     avctx->frame_size = s->frame_size;

  2388. 		}

  2389. 	    }

  2390.         } else if (s->frame_size == -1) {

  2391.             /* free format : find next sync to compute frame size */

  2392. 	    len = MPA_MAX_CODED_FRAME_SIZE - len;

  2393. 	    if (len > buf_size)

  2394. 		len = buf_size;

  2395.             if (len == 0) {

  2396. 		/* frame too long: resync */

  2397.                 s->frame_size = 0;

  2398. 		memcpy(s->inbuf, s->inbuf + 1, s->inbuf_ptr - s->inbuf - 1);

  2399. 		s->inbuf_ptr--;

  2400.             } else {

  2401.                 UINT8 *p, *pend;

  2402.                 UINT32 header1;

  2403.                 int padding;

  2404. 

  2405.                 memcpy(s->inbuf_ptr, buf_ptr, len);

  2406.                 /* check for header */

  2407.                 p = s->inbuf_ptr - 3;

  2408.                 pend = s->inbuf_ptr + len - 4;

  2409.                 while (p <= pend) {

  2410.                     header = (p[0] << 24) | (p[1] << 16) |

  2411.                         (p[2] << 8) | p[3];

  2412.                     header1 = (s->inbuf[0] << 24) | (s->inbuf[1] << 16) |

  2413.                         (s->inbuf[2] << 8) | s->inbuf[3];

  2414.                     /* check with high probability that we have a

  2415.                        valid header */

  2416.                     if ((header & SAME_HEADER_MASK) ==

  2417.                         (header1 & SAME_HEADER_MASK)) {

  2418.                         /* header found: update pointers */

  2419.                         len = (p + 4) - s->inbuf_ptr;

  2420.                         buf_ptr += len;

  2421.                         buf_size -= len;

  2422.                         s->inbuf_ptr = p;

  2423.                         /* compute frame size */

  2424.                         s->free_format_next_header = header;

  2425.                         s->free_format_frame_size = s->inbuf_ptr - s->inbuf;

  2426.                         padding = (header1 >> 9) & 1;

  2427.                         if (s->layer == 1)

  2428.                             s->free_format_frame_size -= padding * 4;

  2429.                         else

  2430.                             s->free_format_frame_size -= padding;

  2431.                         dprintf("free frame size=%d padding=%d\n", 

  2432.                                 s->free_format_frame_size, padding);

  2433.                         decode_header(s, header1);

  2434.                         goto next_data;

  2435.                     }

  2436.                     p++;

  2437.                 }

  2438.                 /* not found: simply increase pointers */

  2439.                 buf_ptr += len;

  2440.                 s->inbuf_ptr += len;

  2441.                 buf_size -= len;

  2442.             }

  2443. 	} else if (len < s->frame_size) {

  2444.             if (s->frame_size > MPA_MAX_CODED_FRAME_SIZE)

  2445.                 s->frame_size = MPA_MAX_CODED_FRAME_SIZE;

  2446. 	    len = s->frame_size - len;

  2447. 	    if (len > buf_size)

  2448. 		len = buf_size;

  2449. 	    memcpy(s->inbuf_ptr, buf_ptr, len);

  2450. 	    buf_ptr += len;

  2451. 	    s->inbuf_ptr += len;

  2452. 	    buf_size -= len;

  2453. 	} else {

  2454.             out_size = mp_decode_frame(s, out_samples);

  2455. 	    s->inbuf_ptr = s->inbuf;

  2456. 	    s->frame_size = 0;

  2457. 	    *data_size = out_size;

  2458. 	    break;

  2459. 	}

  2460.     next_data:

  2461. 	;

  2462.     }

  2463.     return buf_ptr - buf;

  2464. }

  2465. 

  2466. AVCodec mp2_decoder =

  2467. {

  2468.     "mp2",

  2469.     CODEC_TYPE_AUDIO,

  2470.     CODEC_ID_MP2,

  2471.     sizeof(MPADecodeContext),

  2472.     decode_init,

  2473.     NULL,

  2474.     NULL,

  2475.     decode_frame,

  2476. };

  2477. 

  2478. AVCodec mp3_decoder =

  2479. {

  2480.     "mp3",

  2481.     CODEC_TYPE_AUDIO,

  2482.     CODEC_ID_MP3LAME,

  2483.     sizeof(MPADecodeContext),

  2484.     decode_init,

  2485.     NULL,

  2486.     NULL,

  2487.     decode_frame,

  2488. };

  2489. 

  2490. #undef C1

  2491. #undef C2

  2492. #undef C3

  2493. #undef C4

  2494. #undef C5

  2495. #undef C6

  2496. #undef C7

  2497. #undef C8

  2498. #undef FRAC_BITS

  2499. #undef HEADER_SIZE