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FFmpeg/libavcodec/mpegaudiodec.c

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  1. /*

  2.  * MPEG Audio decoder

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

  4.  *

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

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

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

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

  9.  *

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

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

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

  13.  * Lesser General Public License for more details.

  14.  *

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

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

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

  18.  */

  19. 

  20. /**

  21.  * @file mpegaudiodec.c

  22.  * MPEG Audio decoder.

  23.  */ 

  24. 

  25. //#define DEBUG

  26. #include "avcodec.h"

  27. #include "mpegaudio.h"

  28. 

  29. /*

  30.  * TODO:

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

  32.  *  - test lsf / mpeg25 extensively.

  33.  */

  34. 

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

  36.    audio decoder */

  37. #ifdef CONFIG_MPEGAUDIO_HP

  38. #define USE_HIGHPRECISION

  39. #endif

  40. 

  41. #ifdef USE_HIGHPRECISION

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

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

  44. #else

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

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

  47. #endif

  48. 

  49. #define FRAC_ONE    (1 << FRAC_BITS)

  50. 

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

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

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

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

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

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

  57. 

  58. #if FRAC_BITS <= 15

  59. typedef int16_t MPA_INT;

  60. #else

  61. typedef int32_t MPA_INT;

  62. #endif

  63. 

  64. /****************/

  65. 

  66. #define HEADER_SIZE 4

  67. #define BACKSTEP_SIZE 512

  68. 

  69. typedef struct MPADecodeContext {

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

  71.     int inbuf_index;

  72.     uint8_t *inbuf_ptr, *inbuf;

  73.     int frame_size;

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

  75.                                    (zero if currently unknown) */

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

  77.     uint32_t free_format_next_header; 

  78.     int error_protection;

  79.     int layer;

  80.     int sample_rate;

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

  82.     int bit_rate;

  83.     int old_frame_size;

  84.     GetBitContext gb;

  85.     int nb_channels;

  86.     int mode;

  87.     int mode_ext;

  88.     int lsf;

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

  90.     int synth_buf_offset[MPA_MAX_CHANNELS];

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

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

  93. #ifdef DEBUG

  94.     int frame_count;

  95. #endif

  96. } MPADecodeContext;

  97. 

  98. /* layer 3 "granule" */

  99. typedef struct GranuleDef {

  100.     uint8_t scfsi;

  101.     int part2_3_length;

  102.     int big_values;

  103.     int global_gain;

  104.     int scalefac_compress;

  105.     uint8_t block_type;

  106.     uint8_t switch_point;

  107.     int table_select[3];

  108.     int subblock_gain[3];

  109.     uint8_t scalefac_scale;

  110.     uint8_t count1table_select;

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

  112.     int preflag;

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

  114.     uint8_t scale_factors[40];

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

  116. } GranuleDef;

  117. 

  118. #define MODE_EXT_MS_STEREO 2

  119. #define MODE_EXT_I_STEREO  1

  120. 

  121. /* layer 3 huffman tables */

  122. typedef struct HuffTable {

  123.     int xsize;

  124.     const uint8_t *bits;

  125.     const uint16_t *codes;

  126. } HuffTable;

  127. 

  128. #include "mpegaudiodectab.h"

  129. 

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

  131. static VLC huff_vlc[16]; 

  132. static uint8_t *huff_code_table[16];

  133. static VLC huff_quad_vlc[2];

  134. /* computed from band_size_long */

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

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

  137. #define TABLE_4_3_SIZE (8191 + 16)

  138. static int8_t  *table_4_3_exp;

  139. #if FRAC_BITS <= 15

  140. static uint16_t *table_4_3_value;

  141. #else

  142. static uint32_t *table_4_3_value;

  143. #endif

  144. /* intensity stereo coef table */

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

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

  147. static int32_t csa_table[8][2];

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

  149. 

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

  151. static uint16_t scale_factor_modshift[64];

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

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

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

  155. 

  156. #define SCALE_GEN(v) \

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

  158. 

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

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

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

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

  163. };

  164. 

  165. /* 2^(n/4) */

  166. static uint32_t scale_factor_mult3[4] = {

  167.     FIXR(1.0),

  168.     FIXR(1.18920711500272106671),

  169.     FIXR(1.41421356237309504880),

  170.     FIXR(1.68179283050742908605),

  171. };

  172. 

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

  174.     

  175. /* layer 1 unscaling */

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

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

  178. {

  179.     int shift, mod;

  180.     int64_t val;

  181. 

  182.     shift = scale_factor_modshift[scale_factor];

  183.     mod = shift & 3;

  184.     shift >>= 2;

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

  186.     shift += n;

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

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

  189. }

  190. 

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

  192. {

  193.     int shift, mod, val;

  194. 

  195.     shift = scale_factor_modshift[scale_factor];

  196.     mod = shift & 3;

  197.     shift >>= 2;

  198. 

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

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

  201.     if (shift > 0)

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

  203.     return val;

  204. }

  205. 

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

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

  208. {

  209. #if FRAC_BITS <= 15    

  210.     unsigned int m;

  211. #else

  212.     uint64_t m;

  213. #endif

  214.     int e;

  215. 

  216.     e = table_4_3_exp[value];

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

  218.     e = FRAC_BITS - e;

  219. #if FRAC_BITS <= 15    

  220.     if (e > 31)

  221.         e = 31;

  222. #endif

  223.     m = table_4_3_value[value];

  224. #if FRAC_BITS <= 15    

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

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

  227.     return m;

  228. #else

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

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

  231.     return m;

  232. #endif

  233. }

  234. 

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

  236. #define DEV_ORDER 13

  237. 

  238. #define POW_FRAC_BITS 24

  239. #define POW_FRAC_ONE    (1 << POW_FRAC_BITS)

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

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

  242. 

  243. static int dev_4_3_coefs[DEV_ORDER];

  244. 

  245. static int pow_mult3[3] = {

  246.     POW_FIX(1.0),

  247.     POW_FIX(1.25992104989487316476),

  248.     POW_FIX(1.58740105196819947474),

  249. };

  250. 

  251. static void int_pow_init(void)

  252. {

  253.     int i, a;

  254. 

  255.     a = POW_FIX(1.0);

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

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

  258.         dev_4_3_coefs[i] = a;

  259.     }

  260. }

  261. 

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

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

  264. {

  265.     int e, er, eq, j;

  266.     int a, a1;

  267.     

  268.     /* renormalize */

  269.     a = i;

  270.     e = POW_FRAC_BITS;

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

  272.         a = a << 1;

  273.         e--;

  274.     }

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

  276.     a1 = 0;

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

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

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

  280.     /* exponent compute (exact) */

  281.     e = e * 4;

  282.     er = e % 3;

  283.     eq = e / 3;

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

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

  286.         a = a >> 1;

  287.         eq++;

  288.     }

  289.     /* convert to float */

  290.     while (a < POW_FRAC_ONE) {

  291.         a = a << 1;

  292.         eq--;

  293.     }

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

  295. #if POW_FRAC_BITS > FRAC_BITS

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

  297.     /* correct overflow */

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

  299.         a = a >> 1;

  300.         eq++;

  301.     }

  302. #endif

  303.     *exp_ptr = eq;

  304.     return a;

  305. }

  306. 

  307. static int decode_init(AVCodecContext * avctx)

  308. {

  309.     MPADecodeContext *s = avctx->priv_data;

  310.     static int init=0;

  311.     int i, j, k;

  312. 

  313.     if(!init) {

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

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

  316.             int shift, mod;

  317.             /* 1.0 (i = 3) is normalized to 2 ^ FRAC_BITS */

  318.             shift = (i / 3);

  319.             mod = i % 3;

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

  321.         }

  322. 

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

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

  325.             int n, norm;

  326.             n = i + 2;

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

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

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

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

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

  332.                     i, norm, 

  333.                     scale_factor_mult[i][0],

  334.                     scale_factor_mult[i][1],

  335.                     scale_factor_mult[i][2]);

  336.         }

  337.         

  338.         /* window */

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

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

  341.             int v;

  342.             v = mpa_enwindow[i];

  343. #if WFRAC_BITS < 16

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

  345. #endif

  346.             window[i] = v;

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

  348.                 v = -v;

  349.             if (i != 0)

  350.                 window[512 - i] = v;

  351.         }

  352.         

  353.         /* huffman decode tables */

  354.         huff_code_table[0] = NULL;

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

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

  357. 	    int xsize, x, y;

  358.             unsigned int n;

  359.             uint8_t *code_table;

  360. 

  361.             xsize = h->xsize;

  362.             n = xsize * xsize;

  363.             /* XXX: fail test */

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

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

  366.             

  367.             code_table = av_mallocz(n);

  368.             j = 0;

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

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

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

  372.             }

  373.             huff_code_table[i] = code_table;

  374.         }

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

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

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

  378.         }

  379. 

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

  381.             k = 0;

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

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

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

  385.             }

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

  387.         }

  388. 

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

  390. 	if (!av_mallocz_static(&table_4_3_exp,

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

  392. 	    return -1;

  393. 	if (!av_mallocz_static(&table_4_3_value,

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

  395.             return -1;

  396.         

  397.         int_pow_init();

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

  399.             int e, m;

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

  401. #if 0

  402.             /* test code */

  403.             {

  404.                 double f, fm;

  405.                 int e1, m1;

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

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

  408.                 m1 = FIXR(2 * fm);

  409. #if FRAC_BITS <= 15

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

  411.                     m1 = m1 >> 1;

  412.                     e1++;

  413.                 }

  414. #endif

  415.                 e1--;

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

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

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

  419.                 }

  420.             }

  421. #endif

  422.             /* normalized to FRAC_BITS */

  423.             table_4_3_value[i] = m;

  424.             table_4_3_exp[i] = e;

  425.         }

  426.         

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

  428.             float f;

  429.             int v;

  430.             if (i != 6) {

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

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

  433.             } else {

  434.                 v = FIXR(1.0);

  435.             }

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

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

  438.         }

  439.         /* invalid values */

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

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

  442. 

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

  444.             double f;

  445.             int e, k;

  446. 

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

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

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

  450.                 k = i & 1;

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

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

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

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

  455.             }

  456.         }

  457. 

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

  459.             float ci, cs, ca;

  460.             ci = ci_table[i];

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

  462.             ca = cs * ci;

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

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

  465.         }

  466. 

  467.         /* compute mdct windows */

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

  469.             int v;

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

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

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

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

  474.         }

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

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

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

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

  479. 

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

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

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

  483.         }

  484. 

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

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

  487.         

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

  489.            the sign of the right window coefs */

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

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

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

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

  494.             }

  495.         }

  496. 

  497. #if defined(DEBUG)

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

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

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

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

  502.             printf("\n");

  503.         }

  504. #endif

  505.         init = 1;

  506.     }

  507. 

  508.     s->inbuf_index = 0;

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

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

  511. #ifdef DEBUG

  512.     s->frame_count = 0;

  513. #endif

  514.     return 0;

  515. }

  516. 

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

  518. 

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

  520. 

  521. #define COS0_0  FIXR(0.50060299823519630134)

  522. #define COS0_1  FIXR(0.50547095989754365998)

  523. #define COS0_2  FIXR(0.51544730992262454697)

  524. #define COS0_3  FIXR(0.53104259108978417447)

  525. #define COS0_4  FIXR(0.55310389603444452782)

  526. #define COS0_5  FIXR(0.58293496820613387367)

  527. #define COS0_6  FIXR(0.62250412303566481615)

  528. #define COS0_7  FIXR(0.67480834145500574602)

  529. #define COS0_8  FIXR(0.74453627100229844977)

  530. #define COS0_9  FIXR(0.83934964541552703873)

  531. #define COS0_10 FIXR(0.97256823786196069369)

  532. #define COS0_11 FIXR(1.16943993343288495515)

  533. #define COS0_12 FIXR(1.48416461631416627724)

  534. #define COS0_13 FIXR(2.05778100995341155085)

  535. #define COS0_14 FIXR(3.40760841846871878570)

  536. #define COS0_15 FIXR(10.19000812354805681150)

  537. 

  538. #define COS1_0 FIXR(0.50241928618815570551)

  539. #define COS1_1 FIXR(0.52249861493968888062)

  540. #define COS1_2 FIXR(0.56694403481635770368)

  541. #define COS1_3 FIXR(0.64682178335999012954)

  542. #define COS1_4 FIXR(0.78815462345125022473)

  543. #define COS1_5 FIXR(1.06067768599034747134)

  544. #define COS1_6 FIXR(1.72244709823833392782)

  545. #define COS1_7 FIXR(5.10114861868916385802)

  546. 

  547. #define COS2_0 FIXR(0.50979557910415916894)

  548. #define COS2_1 FIXR(0.60134488693504528054)

  549. #define COS2_2 FIXR(0.89997622313641570463)

  550. #define COS2_3 FIXR(2.56291544774150617881)

  551. 

  552. #define COS3_0 FIXR(0.54119610014619698439)

  553. #define COS3_1 FIXR(1.30656296487637652785)

  554. 

  555. #define COS4_0 FIXR(0.70710678118654752439)

  556. 

  557. /* butterfly operator */

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

  559. {\

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

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

  562.     tab[a] = tmp0;\

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

  564. }

  565. 

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

  567. {\

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

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

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

  571. }

  572. 

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

  574. {\

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

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

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

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

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

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

  581. }

  582. 

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

  584. 

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

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

  587. {

  588.     int tmp0, tmp1;

  589. 

  590.     /* pass 1 */

  591.     BF(0, 31, COS0_0);

  592.     BF(1, 30, COS0_1);

  593.     BF(2, 29, COS0_2);

  594.     BF(3, 28, COS0_3);

  595.     BF(4, 27, COS0_4);

  596.     BF(5, 26, COS0_5);

  597.     BF(6, 25, COS0_6);

  598.     BF(7, 24, COS0_7);

  599.     BF(8, 23, COS0_8);

  600.     BF(9, 22, COS0_9);

  601.     BF(10, 21, COS0_10);

  602.     BF(11, 20, COS0_11);

  603.     BF(12, 19, COS0_12);

  604.     BF(13, 18, COS0_13);

  605.     BF(14, 17, COS0_14);

  606.     BF(15, 16, COS0_15);

  607. 

  608.     /* pass 2 */

  609.     BF(0, 15, COS1_0);

  610.     BF(1, 14, COS1_1);

  611.     BF(2, 13, COS1_2);

  612.     BF(3, 12, COS1_3);

  613.     BF(4, 11, COS1_4);

  614.     BF(5, 10, COS1_5);

  615.     BF(6,  9, COS1_6);

  616.     BF(7,  8, COS1_7);

  617.     

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

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

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

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

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

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

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

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

  626.     

  627.     /* pass 3 */

  628.     BF(0, 7, COS2_0);

  629.     BF(1, 6, COS2_1);

  630.     BF(2, 5, COS2_2);

  631.     BF(3, 4, COS2_3);

  632.     

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

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

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

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

  637.     

  638.     BF(16, 23, COS2_0);

  639.     BF(17, 22, COS2_1);

  640.     BF(18, 21, COS2_2);

  641.     BF(19, 20, COS2_3);

  642.     

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

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

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

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

  647. 

  648.     /* pass 4 */

  649.     BF(0, 3, COS3_0);

  650.     BF(1, 2, COS3_1);

  651.     

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

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

  654.     

  655.     BF(8, 11, COS3_0);

  656.     BF(9, 10, COS3_1);

  657.     

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

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

  660.     

  661.     BF(16, 19, COS3_0);

  662.     BF(17, 18, COS3_1);

  663.     

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

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

  666.     

  667.     BF(24, 27, COS3_0);

  668.     BF(25, 26, COS3_1);

  669.     

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

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

  672.     

  673.     /* pass 5 */

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

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

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

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

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

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

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

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

  682.     

  683.     /* pass 6 */

  684.     

  685.     ADD( 8, 12);

  686.     ADD(12, 10);

  687.     ADD(10, 14);

  688.     ADD(14,  9);

  689.     ADD( 9, 13);

  690.     ADD(13, 11);

  691.     ADD(11, 15);

  692. 

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  709.     

  710.     ADD(24, 28);

  711.     ADD(28, 26);

  712.     ADD(26, 30);

  713.     ADD(30, 25);

  714.     ADD(25, 29);

  715.     ADD(29, 27);

  716.     ADD(27, 31);

  717. 

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  734. }

  735. 

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

  737. 

  738. #if FRAC_BITS <= 15

  739. 

  740. #define OUT_SAMPLE(sum)\

  741. {\

  742.     int sum1;\

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

  744.     if (sum1 < -32768)\

  745.         sum1 = -32768;\

  746.     else if (sum1 > 32767)\

  747.         sum1 = 32767;\

  748.     *samples = sum1;\

  749.     samples += incr;\

  750. }

  751. 

  752. #define SUM8(off, op)                           \

  753. {                                               \

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

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

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

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

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

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

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

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

  762. }

  763. 

  764. #else

  765. 

  766. #define OUT_SAMPLE(sum)\

  767. {\

  768.     int sum1;\

  769.     sum1 = (int)((sum + (int64_t_C(1) << (OUT_SHIFT - 1))) >> OUT_SHIFT);\

  770.     if (sum1 < -32768)\

  771.         sum1 = -32768;\

  772.     else if (sum1 > 32767)\

  773.         sum1 = 32767;\

  774.     *samples = sum1;\

  775.     samples += incr;\

  776. }

  777. 

  778. #define SUM8(off, op)                           \

  779. {                                               \

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

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

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

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

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

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

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

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

  788. }

  789. 

  790. #endif

  791. 

  792. /* 32 sub band synthesis filter. Input: 32 sub band samples, Output:

  793.    32 samples. */

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

  795. static void synth_filter(MPADecodeContext *s1,

  796.                          int ch, int16_t *samples, int incr, 

  797.                          int32_t sb_samples[SBLIMIT])

  798. {

  799.     int32_t tmp[32];

  800.     register MPA_INT *synth_buf, *p;

  801.     register MPA_INT *w;

  802.     int j, offset, v;

  803. #if FRAC_BITS <= 15

  804.     int sum;

  805. #else

  806.     int64_t sum;

  807. #endif

  808. 

  809.     dct32(tmp, sb_samples);

  810.     

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

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

  813. 

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

  815.         v = tmp[j];

  816. #if FRAC_BITS <= 15

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

  818.            sound */

  819.         if (v > 32767)

  820.             v = 32767;

  821.         else if (v < -32768)

  822.             v = -32768;

  823. #endif

  824.         synth_buf[j] = v;

  825.     }

  826.     /* copy to avoid wrap */

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

  828. 

  829.     w = window;

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

  831.         sum = 0;

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

  833.         SUM8(0, +=);

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

  835.         SUM8(32, -=);

  836.         OUT_SAMPLE(sum);

  837.         w++;

  838.     }

  839.     

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

  841.     sum = 0;

  842.     SUM8(32, -=);

  843.     OUT_SAMPLE(sum);

  844.     w++;

  845. 

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

  847.         sum = 0;

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

  849.         SUM8(0, -=);

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

  851.         SUM8(32, -=);

  852.         OUT_SAMPLE(sum);

  853.         w++;

  854.     }

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

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

  857. }

  858. 

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

  860. #define C1  FIXR(0.99144486137381041114)

  861. #define C3  FIXR(0.92387953251128675612)

  862. #define C5  FIXR(0.79335334029123516458)

  863. #define C7  FIXR(0.60876142900872063941)

  864. #define C9  FIXR(0.38268343236508977173)

  865. #define C11 FIXR(0.13052619222005159154)

  866. 

  867. /* 12 points IMDCT. We compute it "by hand" by factorizing obvious

  868.    cases. */

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

  870. {

  871.     int tmp;

  872.     int64_t in1_3, in1_9, in4_3, in4_9;

  873. 

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

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

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

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

  878.     

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

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

  881.     out[0] = tmp;

  882.     out[5] = -tmp;

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

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

  885.     out[1] = tmp;

  886.     out[4] = -tmp;

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

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

  889.     out[2] = tmp;

  890.     out[3] = -tmp;

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

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

  893.     out[6] = tmp;

  894.     out[11] = tmp;

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

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

  897.     out[7] = tmp;

  898.     out[10] = tmp;

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

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

  901.     out[8] = tmp;

  902.     out[9] = tmp;

  903. }

  904. 

  905. #undef C1

  906. #undef C3

  907. #undef C5

  908. #undef C7

  909. #undef C9

  910. #undef C11

  911. 

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

  913. #define C1 FIXR(0.98480775301220805936)

  914. #define C2 FIXR(0.93969262078590838405)

  915. #define C3 FIXR(0.86602540378443864676)

  916. #define C4 FIXR(0.76604444311897803520)

  917. #define C5 FIXR(0.64278760968653932632)

  918. #define C6 FIXR(0.5)

  919. #define C7 FIXR(0.34202014332566873304)

  920. #define C8 FIXR(0.17364817766693034885)

  921. 

  922. /* 0.5 / cos(pi*(2*i+1)/36) */

  923. static const int icos36[9] = {

  924.     FIXR(0.50190991877167369479),

  925.     FIXR(0.51763809020504152469),

  926.     FIXR(0.55168895948124587824),

  927.     FIXR(0.61038729438072803416),

  928.     FIXR(0.70710678118654752439),

  929.     FIXR(0.87172339781054900991),

  930.     FIXR(1.18310079157624925896),

  931.     FIXR(1.93185165257813657349),

  932.     FIXR(5.73685662283492756461),

  933. };

  934. 

  935. static const int icos72[18] = {

  936.     /* 0.5 / cos(pi*(2*i+19)/72) */

  937.     FIXR(0.74009361646113053152),

  938.     FIXR(0.82133981585229078570),

  939.     FIXR(0.93057949835178895673),

  940.     FIXR(1.08284028510010010928),

  941.     FIXR(1.30656296487637652785),

  942.     FIXR(1.66275476171152078719),

  943.     FIXR(2.31011315767264929558),

  944.     FIXR(3.83064878777019433457),

  945.     FIXR(11.46279281302667383546),

  946. 

  947.     /* 0.5 / cos(pi*(2*(i + 18) +19)/72) */

  948.     FIXR(-0.67817085245462840086),

  949.     FIXR(-0.63023620700513223342),

  950.     FIXR(-0.59284452371708034528),

  951.     FIXR(-0.56369097343317117734),

  952.     FIXR(-0.54119610014619698439),

  953.     FIXR(-0.52426456257040533932),

  954.     FIXR(-0.51213975715725461845),

  955.     FIXR(-0.50431448029007636036),

  956.     FIXR(-0.50047634258165998492),

  957. };

  958. 

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

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

  961. {

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

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

  964.     int64_t in3_3, in6_6;

  965. 

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

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

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

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

  970. 

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

  972.         tmp1 = tmp + j;

  973.         in1 = in + j;

  974. 

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

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

  977. 

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  998.     }

  999. 

  1000.     i = 0;

  1001.     for(j=0;j<4;j++) {

  1002.         t0 = tmp[i];

  1003.         t1 = tmp[i + 2];

  1004.         s0 = t1 + t0;

  1005.         s2 = t1 - t0;

  1006. 

  1007.         t2 = tmp[i + 1];

  1008.         t3 = tmp[i + 3];

  1009.         s1 = MULL(t3 + t2, icos36[j]);

  1010.         s3 = MULL(t3 - t2, icos36[8 - j]);

  1011.         

  1012.         t0 = MULL(s0 + s1, icos72[9 + 8 - j]);

  1013.         t1 = MULL(s0 - s1, icos72[8 - j]);

  1014.         out[18 + 9 + j] = t0;

  1015.         out[18 + 8 - j] = t0;

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

  1017.         out[8 - j] = t1;

  1018.         

  1019.         t0 = MULL(s2 + s3, icos72[9+j]);

  1020.         t1 = MULL(s2 - s3, icos72[j]);

  1021.         out[18 + 9 + (8 - j)] = t0;

  1022.         out[18 + j] = t0;

  1023.         out[9 + (8 - j)] = -t1;

  1024.         out[j] = t1;

  1025.         i += 4;

  1026.     }

  1027. 

  1028.     s0 = tmp[16];

  1029.     s1 = MULL(tmp[17], icos36[4]);

  1030.     t0 = MULL(s0 + s1, icos72[9 + 4]);

  1031.     t1 = MULL(s0 - s1, icos72[4]);

  1032.     out[18 + 9 + 4] = t0;

  1033.     out[18 + 8 - 4] = t0;

  1034.     out[9 + 4] = -t1;

  1035.     out[8 - 4] = t1;

  1036. }

  1037. 

  1038. /* fast header check for resync */

  1039. static int check_header(uint32_t header)

  1040. {

  1041.     /* header */

  1042.     if ((header & 0xffe00000) != 0xffe00000)

  1043. 	return -1;

  1044.     /* layer check */

  1045.     if (((header >> 17) & 3) == 0)

  1046. 	return -1;

  1047.     /* bit rate */

  1048.     if (((header >> 12) & 0xf) == 0xf)

  1049. 	return -1;

  1050.     /* frequency */

  1051.     if (((header >> 10) & 3) == 3)

  1052. 	return -1;

  1053.     return 0;

  1054. }

  1055. 

  1056. /* header + layer + bitrate + freq + lsf/mpeg25 */

  1057. #define SAME_HEADER_MASK \

  1058.    (0xffe00000 | (3 << 17) | (0xf << 12) | (3 << 10) | (3 << 19))

  1059. 

  1060. /* header decoding. MUST check the header before because no

  1061.    consistency check is done there. Return 1 if free format found and

  1062.    that the frame size must be computed externally */

  1063. static int decode_header(MPADecodeContext *s, uint32_t header)

  1064. {

  1065.     int sample_rate, frame_size, mpeg25, padding;

  1066.     int sample_rate_index, bitrate_index;

  1067.     if (header & (1<<20)) {

  1068.         s->lsf = (header & (1<<19)) ? 0 : 1;

  1069.         mpeg25 = 0;

  1070.     } else {

  1071.         s->lsf = 1;

  1072.         mpeg25 = 1;

  1073.     }

  1074.     

  1075.     s->layer = 4 - ((header >> 17) & 3);

  1076.     /* extract frequency */

  1077.     sample_rate_index = (header >> 10) & 3;

  1078.     sample_rate = mpa_freq_tab[sample_rate_index] >> (s->lsf + mpeg25);

  1079.     sample_rate_index += 3 * (s->lsf + mpeg25);

  1080.     s->sample_rate_index = sample_rate_index;

  1081.     s->error_protection = ((header >> 16) & 1) ^ 1;

  1082.     s->sample_rate = sample_rate;

  1083. 

  1084.     bitrate_index = (header >> 12) & 0xf;

  1085.     padding = (header >> 9) & 1;

  1086.     //extension = (header >> 8) & 1;

  1087.     s->mode = (header >> 6) & 3;

  1088.     s->mode_ext = (header >> 4) & 3;

  1089.     //copyright = (header >> 3) & 1;

  1090.     //original = (header >> 2) & 1;

  1091.     //emphasis = header & 3;

  1092. 

  1093.     if (s->mode == MPA_MONO)

  1094.         s->nb_channels = 1;

  1095.     else

  1096.         s->nb_channels = 2;

  1097.     

  1098.     if (bitrate_index != 0) {

  1099.         frame_size = mpa_bitrate_tab[s->lsf][s->layer - 1][bitrate_index];

  1100.         s->bit_rate = frame_size * 1000;

  1101.         switch(s->layer) {

  1102.         case 1:

  1103.             frame_size = (frame_size * 12000) / sample_rate;

  1104.             frame_size = (frame_size + padding) * 4;

  1105.             break;

  1106.         case 2:

  1107.             frame_size = (frame_size * 144000) / sample_rate;

  1108.             frame_size += padding;

  1109.             break;

  1110.         default:

  1111.         case 3:

  1112.             frame_size = (frame_size * 144000) / (sample_rate << s->lsf);

  1113.             frame_size += padding;

  1114.             break;

  1115.         }

  1116.         s->frame_size = frame_size;

  1117.     } else {

  1118.         /* if no frame size computed, signal it */

  1119.         if (!s->free_format_frame_size)

  1120.             return 1;

  1121.         /* free format: compute bitrate and real frame size from the

  1122.            frame size we extracted by reading the bitstream */

  1123.         s->frame_size = s->free_format_frame_size;

  1124.         switch(s->layer) {

  1125.         case 1:

  1126.             s->frame_size += padding  * 4;

  1127.             s->bit_rate = (s->frame_size * sample_rate) / 48000;

  1128.             break;

  1129.         case 2:

  1130.             s->frame_size += padding;

  1131.             s->bit_rate = (s->frame_size * sample_rate) / 144000;

  1132.             break;

  1133.         default:

  1134.         case 3:

  1135.             s->frame_size += padding;

  1136.             s->bit_rate = (s->frame_size * (sample_rate << s->lsf)) / 144000;

  1137.             break;

  1138.         }

  1139.     }

  1140.     

  1141. #if defined(DEBUG)

  1142.     printf("layer%d, %d Hz, %d kbits/s, ",

  1143.            s->layer, s->sample_rate, s->bit_rate);

  1144.     if (s->nb_channels == 2) {

  1145.         if (s->layer == 3) {

  1146.             if (s->mode_ext & MODE_EXT_MS_STEREO)

  1147.                 printf("ms-");

  1148.             if (s->mode_ext & MODE_EXT_I_STEREO)

  1149.                 printf("i-");

  1150.         }

  1151.         printf("stereo");

  1152.     } else {

  1153.         printf("mono");

  1154.     }

  1155.     printf("\n");

  1156. #endif

  1157.     return 0;

  1158. }

  1159. 

  1160. /* return the number of decoded frames */

  1161. static int mp_decode_layer1(MPADecodeContext *s)

  1162. {

  1163.     int bound, i, v, n, ch, j, mant;

  1164.     uint8_t allocation[MPA_MAX_CHANNELS][SBLIMIT];

  1165.     uint8_t scale_factors[MPA_MAX_CHANNELS][SBLIMIT];

  1166. 

  1167.     if (s->mode == MPA_JSTEREO) 

  1168.         bound = (s->mode_ext + 1) * 4;

  1169.     else

  1170.         bound = SBLIMIT;

  1171. 

  1172.     /* allocation bits */

  1173.     for(i=0;i<bound;i++) {

  1174.         for(ch=0;ch<s->nb_channels;ch++) {

  1175.             allocation[ch][i] = get_bits(&s->gb, 4);

  1176.         }

  1177.     }

  1178.     for(i=bound;i<SBLIMIT;i++) {

  1179.         allocation[0][i] = get_bits(&s->gb, 4);

  1180.     }

  1181. 

  1182.     /* scale factors */

  1183.     for(i=0;i<bound;i++) {

  1184.         for(ch=0;ch<s->nb_channels;ch++) {

  1185.             if (allocation[ch][i])

  1186.                 scale_factors[ch][i] = get_bits(&s->gb, 6);

  1187.         }

  1188.     }

  1189.     for(i=bound;i<SBLIMIT;i++) {

  1190.         if (allocation[0][i]) {

  1191.             scale_factors[0][i] = get_bits(&s->gb, 6);

  1192.             scale_factors[1][i] = get_bits(&s->gb, 6);

  1193.         }

  1194.     }

  1195.     

  1196.     /* compute samples */

  1197.     for(j=0;j<12;j++) {

  1198.         for(i=0;i<bound;i++) {

  1199.             for(ch=0;ch<s->nb_channels;ch++) {

  1200.                 n = allocation[ch][i];

  1201.                 if (n) {

  1202.                     mant = get_bits(&s->gb, n + 1);

  1203.                     v = l1_unscale(n, mant, scale_factors[ch][i]);

  1204.                 } else {

  1205.                     v = 0;

  1206.                 }

  1207.                 s->sb_samples[ch][j][i] = v;

  1208.             }

  1209.         }

  1210.         for(i=bound;i<SBLIMIT;i++) {

  1211.             n = allocation[0][i];

  1212.             if (n) {

  1213.                 mant = get_bits(&s->gb, n + 1);

  1214.                 v = l1_unscale(n, mant, scale_factors[0][i]);

  1215.                 s->sb_samples[0][j][i] = v;

  1216.                 v = l1_unscale(n, mant, scale_factors[1][i]);

  1217.                 s->sb_samples[1][j][i] = v;

  1218.             } else {

  1219.                 s->sb_samples[0][j][i] = 0;

  1220.                 s->sb_samples[1][j][i] = 0;

  1221.             }

  1222.         }

  1223.     }

  1224.     return 12;

  1225. }

  1226. 

  1227. /* bitrate is in kb/s */

  1228. int l2_select_table(int bitrate, int nb_channels, int freq, int lsf)

  1229. {

  1230.     int ch_bitrate, table;

  1231.     

  1232.     ch_bitrate = bitrate / nb_channels;

  1233.     if (!lsf) {

  1234.         if ((freq == 48000 && ch_bitrate >= 56) ||

  1235.             (ch_bitrate >= 56 && ch_bitrate <= 80)) 

  1236.             table = 0;

  1237.         else if (freq != 48000 && ch_bitrate >= 96) 

  1238.             table = 1;

  1239.         else if (freq != 32000 && ch_bitrate <= 48) 

  1240.             table = 2;

  1241.         else 

  1242.             table = 3;

  1243.     } else {

  1244.         table = 4;

  1245.     }

  1246.     return table;

  1247. }

  1248. 

  1249. static int mp_decode_layer2(MPADecodeContext *s)

  1250. {

  1251.     int sblimit; /* number of used subbands */

  1252.     const unsigned char *alloc_table;

  1253.     int table, bit_alloc_bits, i, j, ch, bound, v;

  1254.     unsigned char bit_alloc[MPA_MAX_CHANNELS][SBLIMIT];

  1255.     unsigned char scale_code[MPA_MAX_CHANNELS][SBLIMIT];

  1256.     unsigned char scale_factors[MPA_MAX_CHANNELS][SBLIMIT][3], *sf;

  1257.     int scale, qindex, bits, steps, k, l, m, b;

  1258. 

  1259.     /* select decoding table */

  1260.     table = l2_select_table(s->bit_rate / 1000, s->nb_channels, 

  1261.                             s->sample_rate, s->lsf);

  1262.     sblimit = sblimit_table[table];

  1263.     alloc_table = alloc_tables[table];

  1264. 

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

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

  1267.     else

  1268.         bound = sblimit;

  1269. 

  1270.     dprintf("bound=%d sblimit=%d\n", bound, sblimit);

  1271.     /* parse bit allocation */

  1272.     j = 0;

  1273.     for(i=0;i<bound;i++) {

  1274.         bit_alloc_bits = alloc_table[j];

  1275.         for(ch=0;ch<s->nb_channels;ch++) {

  1276.             bit_alloc[ch][i] = get_bits(&s->gb, bit_alloc_bits);

  1277.         }

  1278.         j += 1 << bit_alloc_bits;

  1279.     }

  1280.     for(i=bound;i<sblimit;i++) {

  1281.         bit_alloc_bits = alloc_table[j];

  1282.         v = get_bits(&s->gb, bit_alloc_bits);

  1283.         bit_alloc[0][i] = v;

  1284.         bit_alloc[1][i] = v;

  1285.         j += 1 << bit_alloc_bits;

  1286.     }

  1287. 

  1288. #ifdef DEBUG

  1289.     {

  1290.         for(ch=0;ch<s->nb_channels;ch++) {

  1291.             for(i=0;i<sblimit;i++)

  1292.                 printf(" %d", bit_alloc[ch][i]);

  1293.             printf("\n");

  1294.         }

  1295.     }

  1296. #endif

  1297. 

  1298.     /* scale codes */

  1299.     for(i=0;i<sblimit;i++) {

  1300.         for(ch=0;ch<s->nb_channels;ch++) {

  1301.             if (bit_alloc[ch][i]) 

  1302.                 scale_code[ch][i] = get_bits(&s->gb, 2);

  1303.         }

  1304.     }

  1305.     

  1306.     /* scale factors */

  1307.     for(i=0;i<sblimit;i++) {

  1308.         for(ch=0;ch<s->nb_channels;ch++) {

  1309.             if (bit_alloc[ch][i]) {

  1310.                 sf = scale_factors[ch][i];

  1311.                 switch(scale_code[ch][i]) {

  1312.                 default:

  1313.                 case 0:

  1314.                     sf[0] = get_bits(&s->gb, 6);

  1315.                     sf[1] = get_bits(&s->gb, 6);

  1316.                     sf[2] = get_bits(&s->gb, 6);

  1317.                     break;

  1318.                 case 2:

  1319.                     sf[0] = get_bits(&s->gb, 6);

  1320.                     sf[1] = sf[0];

  1321.                     sf[2] = sf[0];

  1322.                     break;

  1323.                 case 1:

  1324.                     sf[0] = get_bits(&s->gb, 6);

  1325.                     sf[2] = get_bits(&s->gb, 6);

  1326.                     sf[1] = sf[0];

  1327.                     break;

  1328.                 case 3:

  1329.                     sf[0] = get_bits(&s->gb, 6);

  1330.                     sf[2] = get_bits(&s->gb, 6);

  1331.                     sf[1] = sf[2];

  1332.                     break;

  1333.                 }

  1334.             }

  1335.         }

  1336.     }

  1337. 

  1338. #ifdef DEBUG

  1339.     for(ch=0;ch<s->nb_channels;ch++) {

  1340.         for(i=0;i<sblimit;i++) {

  1341.             if (bit_alloc[ch][i]) {

  1342.                 sf = scale_factors[ch][i];

  1343.                 printf(" %d %d %d", sf[0], sf[1], sf[2]);

  1344.             } else {

  1345.                 printf(" -");

  1346.             }

  1347.         }

  1348.         printf("\n");

  1349.     }

  1350. #endif

  1351. 

  1352.     /* samples */

  1353.     for(k=0;k<3;k++) {

  1354.         for(l=0;l<12;l+=3) {

  1355.             j = 0;

  1356.             for(i=0;i<bound;i++) {

  1357.                 bit_alloc_bits = alloc_table[j];

  1358.                 for(ch=0;ch<s->nb_channels;ch++) {

  1359.                     b = bit_alloc[ch][i];

  1360.                     if (b) {

  1361.                         scale = scale_factors[ch][i][k];

  1362.                         qindex = alloc_table[j+b];

  1363.                         bits = quant_bits[qindex];

  1364.                         if (bits < 0) {

  1365.                             /* 3 values at the same time */

  1366.                             v = get_bits(&s->gb, -bits);

  1367.                             steps = quant_steps[qindex];

  1368.                             s->sb_samples[ch][k * 12 + l + 0][i] = 

  1369.                                 l2_unscale_group(steps, v % steps, scale);

  1370.                             v = v / steps;

  1371.                             s->sb_samples[ch][k * 12 + l + 1][i] = 

  1372.                                 l2_unscale_group(steps, v % steps, scale);

  1373.                             v = v / steps;

  1374.                             s->sb_samples[ch][k * 12 + l + 2][i] = 

  1375.                                 l2_unscale_group(steps, v, scale);

  1376.                         } else {

  1377.                             for(m=0;m<3;m++) {

  1378.                                 v = get_bits(&s->gb, bits);

  1379.                                 v = l1_unscale(bits - 1, v, scale);

  1380.                                 s->sb_samples[ch][k * 12 + l + m][i] = v;

  1381.                             }

  1382.                         }

  1383.                     } else {

  1384.                         s->sb_samples[ch][k * 12 + l + 0][i] = 0;

  1385.                         s->sb_samples[ch][k * 12 + l + 1][i] = 0;

  1386.                         s->sb_samples[ch][k * 12 + l + 2][i] = 0;

  1387.                     }

  1388.                 }

  1389.                 /* next subband in alloc table */

  1390.                 j += 1 << bit_alloc_bits; 

  1391.             }

  1392.             /* XXX: find a way to avoid this duplication of code */

  1393.             for(i=bound;i<sblimit;i++) {

  1394.                 bit_alloc_bits = alloc_table[j];

  1395.                 b = bit_alloc[0][i];

  1396.                 if (b) {

  1397.                     int mant, scale0, scale1;

  1398.                     scale0 = scale_factors[0][i][k];

  1399.                     scale1 = scale_factors[1][i][k];

  1400.                     qindex = alloc_table[j+b];

  1401.                     bits = quant_bits[qindex];

  1402.                     if (bits < 0) {

  1403.                         /* 3 values at the same time */

  1404.                         v = get_bits(&s->gb, -bits);

  1405.                         steps = quant_steps[qindex];

  1406.                         mant = v % steps;

  1407.                         v = v / steps;

  1408.                         s->sb_samples[0][k * 12 + l + 0][i] = 

  1409.                             l2_unscale_group(steps, mant, scale0);

  1410.                         s->sb_samples[1][k * 12 + l + 0][i] = 

  1411.                             l2_unscale_group(steps, mant, scale1);

  1412.                         mant = v % steps;

  1413.                         v = v / steps;

  1414.                         s->sb_samples[0][k * 12 + l + 1][i] = 

  1415.                             l2_unscale_group(steps, mant, scale0);

  1416.                         s->sb_samples[1][k * 12 + l + 1][i] = 

  1417.                             l2_unscale_group(steps, mant, scale1);

  1418.                         s->sb_samples[0][k * 12 + l + 2][i] = 

  1419.                             l2_unscale_group(steps, v, scale0);

  1420.                         s->sb_samples[1][k * 12 + l + 2][i] = 

  1421.                             l2_unscale_group(steps, v, scale1);

  1422.                     } else {

  1423.                         for(m=0;m<3;m++) {

  1424.                             mant = get_bits(&s->gb, bits);

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

  1426.                                 l1_unscale(bits - 1, mant, scale0);

  1427.                             s->sb_samples[1][k * 12 + l + m][i] = 

  1428.                                 l1_unscale(bits - 1, mant, scale1);

  1429.                         }

  1430.                     }

  1431.                 } else {

  1432.                     s->sb_samples[0][k * 12 + l + 0][i] = 0;

  1433.                     s->sb_samples[0][k * 12 + l + 1][i] = 0;

  1434.                     s->sb_samples[0][k * 12 + l + 2][i] = 0;

  1435.                     s->sb_samples[1][k * 12 + l + 0][i] = 0;

  1436.                     s->sb_samples[1][k * 12 + l + 1][i] = 0;

  1437.                     s->sb_samples[1][k * 12 + l + 2][i] = 0;

  1438.                 }

  1439.                 /* next subband in alloc table */

  1440.                 j += 1 << bit_alloc_bits; 

  1441.             }

  1442.             /* fill remaining samples to zero */

  1443.             for(i=sblimit;i<SBLIMIT;i++) {

  1444.                 for(ch=0;ch<s->nb_channels;ch++) {

  1445.                     s->sb_samples[ch][k * 12 + l + 0][i] = 0;

  1446.                     s->sb_samples[ch][k * 12 + l + 1][i] = 0;

  1447.                     s->sb_samples[ch][k * 12 + l + 2][i] = 0;

  1448.                 }

  1449.             }

  1450.         }

  1451.     }

  1452.     return 3 * 12;

  1453. }

  1454. 

  1455. /*

  1456.  * Seek back in the stream for backstep bytes (at most 511 bytes)

  1457.  */

  1458. static void seek_to_maindata(MPADecodeContext *s, unsigned int backstep)

  1459. {

  1460.     uint8_t *ptr;

  1461. 

  1462.     /* compute current position in stream */

  1463.     ptr = s->gb.buffer + (get_bits_count(&s->gb)>>3);

  1464. 

  1465.     /* copy old data before current one */

  1466.     ptr -= backstep;

  1467.     memcpy(ptr, s->inbuf1[s->inbuf_index ^ 1] + 

  1468.            BACKSTEP_SIZE + s->old_frame_size - backstep, backstep);

  1469.     /* init get bits again */

  1470.     init_get_bits(&s->gb, ptr, (s->frame_size + backstep)*8);

  1471. 

  1472.     /* prepare next buffer */

  1473.     s->inbuf_index ^= 1;

  1474.     s->inbuf = &s->inbuf1[s->inbuf_index][BACKSTEP_SIZE];

  1475.     s->old_frame_size = s->frame_size;

  1476. }

  1477. 

  1478. static inline void lsf_sf_expand(int *slen,

  1479.                                  int sf, int n1, int n2, int n3)

  1480. {

  1481.     if (n3) {

  1482.         slen[3] = sf % n3;

  1483.         sf /= n3;

  1484.     } else {

  1485.         slen[3] = 0;

  1486.     }

  1487.     if (n2) {

  1488.         slen[2] = sf % n2;

  1489.         sf /= n2;

  1490.     } else {

  1491.         slen[2] = 0;

  1492.     }

  1493.     slen[1] = sf % n1;

  1494.     sf /= n1;

  1495.     slen[0] = sf;

  1496. }

  1497. 

  1498. static void exponents_from_scale_factors(MPADecodeContext *s, 

  1499.                                          GranuleDef *g,

  1500.                                          int16_t *exponents)

  1501. {

  1502.     const uint8_t *bstab, *pretab;

  1503.     int len, i, j, k, l, v0, shift, gain, gains[3];

  1504.     int16_t *exp_ptr;

  1505. 

  1506.     exp_ptr = exponents;

  1507.     gain = g->global_gain - 210;

  1508.     shift = g->scalefac_scale + 1;

  1509. 

  1510.     bstab = band_size_long[s->sample_rate_index];

  1511.     pretab = mpa_pretab[g->preflag];

  1512.     for(i=0;i<g->long_end;i++) {

  1513.         v0 = gain - ((g->scale_factors[i] + pretab[i]) << shift);

  1514.         len = bstab[i];

  1515.         for(j=len;j>0;j--)

  1516.             *exp_ptr++ = v0;

  1517.     }

  1518. 

  1519.     if (g->short_start < 13) {

  1520.         bstab = band_size_short[s->sample_rate_index];

  1521.         gains[0] = gain - (g->subblock_gain[0] << 3);

  1522.         gains[1] = gain - (g->subblock_gain[1] << 3);

  1523.         gains[2] = gain - (g->subblock_gain[2] << 3);

  1524.         k = g->long_end;

  1525.         for(i=g->short_start;i<13;i++) {

  1526.             len = bstab[i];

  1527.             for(l=0;l<3;l++) {

  1528.                 v0 = gains[l] - (g->scale_factors[k++] << shift);

  1529.                 for(j=len;j>0;j--)

  1530.                 *exp_ptr++ = v0;

  1531.             }

  1532.         }

  1533.     }

  1534. }

  1535. 

  1536. /* handle n = 0 too */

  1537. static inline int get_bitsz(GetBitContext *s, int n)

  1538. {

  1539.     if (n == 0)

  1540.         return 0;

  1541.     else

  1542.         return get_bits(s, n);

  1543. }

  1544. 

  1545. static int huffman_decode(MPADecodeContext *s, GranuleDef *g,

  1546.                           int16_t *exponents, int end_pos)

  1547. {

  1548.     int s_index;

  1549.     int linbits, code, x, y, l, v, i, j, k, pos;

  1550.     GetBitContext last_gb;

  1551.     VLC *vlc;

  1552.     uint8_t *code_table;

  1553. 

  1554.     /* low frequencies (called big values) */

  1555.     s_index = 0;

  1556.     for(i=0;i<3;i++) {

  1557.         j = g->region_size[i];

  1558.         if (j == 0)

  1559.             continue;

  1560.         /* select vlc table */

  1561.         k = g->table_select[i];

  1562.         l = mpa_huff_data[k][0];

  1563.         linbits = mpa_huff_data[k][1];

  1564.         vlc = &huff_vlc[l];

  1565.         code_table = huff_code_table[l];

  1566. 

  1567.         /* read huffcode and compute each couple */

  1568.         for(;j>0;j--) {

  1569.             if (get_bits_count(&s->gb) >= end_pos)

  1570.                 break;

  1571.             if (code_table) {

  1572.                 code = get_vlc(&s->gb, vlc);

  1573.                 if (code < 0)

  1574.                     return -1;

  1575.                 y = code_table[code];

  1576.                 x = y >> 4;

  1577.                 y = y & 0x0f;

  1578.             } else {

  1579.                 x = 0;

  1580.                 y = 0;

  1581.             }

  1582.             dprintf("region=%d n=%d x=%d y=%d exp=%d\n", 

  1583.                     i, g->region_size[i] - j, x, y, exponents[s_index]);

  1584.             if (x) {

  1585.                 if (x == 15)

  1586.                     x += get_bitsz(&s->gb, linbits);

  1587.                 v = l3_unscale(x, exponents[s_index]);

  1588.                 if (get_bits1(&s->gb))

  1589.                     v = -v;

  1590.             } else {

  1591.                 v = 0;

  1592.             }

  1593.             g->sb_hybrid[s_index++] = v;

  1594.             if (y) {

  1595.                 if (y == 15)

  1596.                     y += get_bitsz(&s->gb, linbits);

  1597.                 v = l3_unscale(y, exponents[s_index]);

  1598.                 if (get_bits1(&s->gb))

  1599.                     v = -v;

  1600.             } else {

  1601.                 v = 0;

  1602.             }

  1603.             g->sb_hybrid[s_index++] = v;

  1604.         }

  1605.     }

  1606.             

  1607.     /* high frequencies */

  1608.     vlc = &huff_quad_vlc[g->count1table_select];

  1609.     last_gb.buffer = NULL;

  1610.     while (s_index <= 572) {

  1611.         pos = get_bits_count(&s->gb);

  1612.         if (pos >= end_pos) {

  1613.             if (pos > end_pos && last_gb.buffer != NULL) {

  1614.                 /* some encoders generate an incorrect size for this

  1615.                    part. We must go back into the data */

  1616.                 s_index -= 4;

  1617.                 s->gb = last_gb;

  1618.             }

  1619.             break;

  1620.         }

  1621.         last_gb= s->gb;

  1622. 

  1623.         code = get_vlc(&s->gb, vlc);

  1624.         dprintf("t=%d code=%d\n", g->count1table_select, code);

  1625.         if (code < 0)

  1626.             return -1;

  1627.         for(i=0;i<4;i++) {

  1628.             if (code & (8 >> i)) {

  1629.                 /* non zero value. Could use a hand coded function for

  1630.                    'one' value */

  1631.                 v = l3_unscale(1, exponents[s_index]);

  1632.                 if(get_bits1(&s->gb))

  1633.                     v = -v;

  1634.             } else {

  1635.                 v = 0;

  1636.             }

  1637.             g->sb_hybrid[s_index++] = v;

  1638.         }

  1639.     }

  1640.     while (s_index < 576)

  1641.         g->sb_hybrid[s_index++] = 0;

  1642.     return 0;

  1643. }

  1644. 

  1645. /* Reorder short blocks from bitstream order to interleaved order. It

  1646.    would be faster to do it in parsing, but the code would be far more

  1647.    complicated */

  1648. static void reorder_block(MPADecodeContext *s, GranuleDef *g)

  1649. {

  1650.     int i, j, k, len;

  1651.     int32_t *ptr, *dst, *ptr1;

  1652.     int32_t tmp[576];

  1653. 

  1654.     if (g->block_type != 2)

  1655.         return;

  1656. 

  1657.     if (g->switch_point) {

  1658.         if (s->sample_rate_index != 8) {

  1659.             ptr = g->sb_hybrid + 36;

  1660.         } else {

  1661.             ptr = g->sb_hybrid + 48;

  1662.         }

  1663.     } else {

  1664.         ptr = g->sb_hybrid;

  1665.     }

  1666.     

  1667.     for(i=g->short_start;i<13;i++) {

  1668.         len = band_size_short[s->sample_rate_index][i];

  1669.         ptr1 = ptr;

  1670.         for(k=0;k<3;k++) {

  1671.             dst = tmp + k;

  1672.             for(j=len;j>0;j--) {

  1673.                 *dst = *ptr++;

  1674.                 dst += 3;

  1675.             }

  1676.         }

  1677.         memcpy(ptr1, tmp, len * 3 * sizeof(int32_t));

  1678.     }

  1679. }

  1680. 

  1681. #define ISQRT2 FIXR(0.70710678118654752440)

  1682. 

  1683. static void compute_stereo(MPADecodeContext *s,

  1684.                            GranuleDef *g0, GranuleDef *g1)

  1685. {

  1686.     int i, j, k, l;

  1687.     int32_t v1, v2;

  1688.     int sf_max, tmp0, tmp1, sf, len, non_zero_found;

  1689.     int32_t (*is_tab)[16];

  1690.     int32_t *tab0, *tab1;

  1691.     int non_zero_found_short[3];

  1692. 

  1693.     /* intensity stereo */

  1694.     if (s->mode_ext & MODE_EXT_I_STEREO) {

  1695.         if (!s->lsf) {

  1696.             is_tab = is_table;

  1697.             sf_max = 7;

  1698.         } else {

  1699.             is_tab = is_table_lsf[g1->scalefac_compress & 1];

  1700.             sf_max = 16;

  1701.         }

  1702.             

  1703.         tab0 = g0->sb_hybrid + 576;

  1704.         tab1 = g1->sb_hybrid + 576;

  1705. 

  1706.         non_zero_found_short[0] = 0;

  1707.         non_zero_found_short[1] = 0;

  1708.         non_zero_found_short[2] = 0;

  1709.         k = (13 - g1->short_start) * 3 + g1->long_end - 3;

  1710.         for(i = 12;i >= g1->short_start;i--) {

  1711.             /* for last band, use previous scale factor */

  1712.             if (i != 11)

  1713.                 k -= 3;

  1714.             len = band_size_short[s->sample_rate_index][i];

  1715.             for(l=2;l>=0;l--) {

  1716.                 tab0 -= len;

  1717.                 tab1 -= len;

  1718.                 if (!non_zero_found_short[l]) {

  1719.                     /* test if non zero band. if so, stop doing i-stereo */

  1720.                     for(j=0;j<len;j++) {

  1721.                         if (tab1[j] != 0) {

  1722.                             non_zero_found_short[l] = 1;

  1723.                             goto found1;

  1724.                         }

  1725.                     }

  1726.                     sf = g1->scale_factors[k + l];

  1727.                     if (sf >= sf_max)

  1728.                         goto found1;

  1729. 

  1730.                     v1 = is_tab[0][sf];

  1731.                     v2 = is_tab[1][sf];

  1732.                     for(j=0;j<len;j++) {

  1733.                         tmp0 = tab0[j];

  1734.                         tab0[j] = MULL(tmp0, v1);

  1735.                         tab1[j] = MULL(tmp0, v2);

  1736.                     }

  1737.                 } else {

  1738.                 found1:

  1739.                     if (s->mode_ext & MODE_EXT_MS_STEREO) {

  1740.                         /* lower part of the spectrum : do ms stereo

  1741.                            if enabled */

  1742.                         for(j=0;j<len;j++) {

  1743.                             tmp0 = tab0[j];

  1744.                             tmp1 = tab1[j];

  1745.                             tab0[j] = MULL(tmp0 + tmp1, ISQRT2);

  1746.                             tab1[j] = MULL(tmp0 - tmp1, ISQRT2);

  1747.                         }

  1748.                     }

  1749.                 }

  1750.             }

  1751.         }

  1752. 

  1753.         non_zero_found = non_zero_found_short[0] | 

  1754.             non_zero_found_short[1] | 

  1755.             non_zero_found_short[2];

  1756. 

  1757.         for(i = g1->long_end - 1;i >= 0;i--) {

  1758.             len = band_size_long[s->sample_rate_index][i];

  1759.             tab0 -= len;

  1760.             tab1 -= len;

  1761.             /* test if non zero band. if so, stop doing i-stereo */

  1762.             if (!non_zero_found) {

  1763.                 for(j=0;j<len;j++) {

  1764.                     if (tab1[j] != 0) {

  1765.                         non_zero_found = 1;

  1766.                         goto found2;

  1767.                     }

  1768.                 }

  1769.                 /* for last band, use previous scale factor */

  1770.                 k = (i == 21) ? 20 : i;

  1771.                 sf = g1->scale_factors[k];

  1772.                 if (sf >= sf_max)

  1773.                     goto found2;

  1774.                 v1 = is_tab[0][sf];

  1775.                 v2 = is_tab[1][sf];

  1776.                 for(j=0;j<len;j++) {

  1777.                     tmp0 = tab0[j];

  1778.                     tab0[j] = MULL(tmp0, v1);

  1779.                     tab1[j] = MULL(tmp0, v2);

  1780.                 }

  1781.             } else {

  1782.             found2:

  1783.                 if (s->mode_ext & MODE_EXT_MS_STEREO) {

  1784.                     /* lower part of the spectrum : do ms stereo

  1785.                        if enabled */

  1786.                     for(j=0;j<len;j++) {

  1787.                         tmp0 = tab0[j];

  1788.                         tmp1 = tab1[j];

  1789.                         tab0[j] = MULL(tmp0 + tmp1, ISQRT2);

  1790.                         tab1[j] = MULL(tmp0 - tmp1, ISQRT2);

  1791.                     }

  1792.                 }

  1793.             }

  1794.         }

  1795.     } else if (s->mode_ext & MODE_EXT_MS_STEREO) {

  1796.         /* ms stereo ONLY */

  1797.         /* NOTE: the 1/sqrt(2) normalization factor is included in the

  1798.            global gain */

  1799.         tab0 = g0->sb_hybrid;

  1800.         tab1 = g1->sb_hybrid;

  1801.         for(i=0;i<576;i++) {

  1802.             tmp0 = tab0[i];

  1803.             tmp1 = tab1[i];

  1804.             tab0[i] = tmp0 + tmp1;

  1805.             tab1[i] = tmp0 - tmp1;

  1806.         }

  1807.     }

  1808. }

  1809. 

  1810. static void compute_antialias(MPADecodeContext *s,

  1811.                               GranuleDef *g)

  1812. {

  1813.     int32_t *ptr, *p0, *p1, *csa;

  1814.     int n, tmp0, tmp1, i, j;

  1815. 

  1816.     /* we antialias only "long" bands */

  1817.     if (g->block_type == 2) {

  1818.         if (!g->switch_point)

  1819.             return;

  1820.         /* XXX: check this for 8000Hz case */

  1821.         n = 1;

  1822.     } else {

  1823.         n = SBLIMIT - 1;

  1824.     }

  1825.     

  1826.     ptr = g->sb_hybrid + 18;

  1827.     for(i = n;i > 0;i--) {

  1828.         p0 = ptr - 1;

  1829.         p1 = ptr;

  1830.         csa = &csa_table[0][0];

  1831.         for(j=0;j<8;j++) {

  1832.             tmp0 = *p0;

  1833.             tmp1 = *p1;

  1834.             *p0 = FRAC_RND(MUL64(tmp0, csa[0]) - MUL64(tmp1, csa[1]));

  1835.             *p1 = FRAC_RND(MUL64(tmp0, csa[1]) + MUL64(tmp1, csa[0]));

  1836.             p0--;

  1837.             p1++;

  1838.             csa += 2;

  1839.         }

  1840.         ptr += 18;

  1841.     }

  1842. }

  1843. 

  1844. static void compute_imdct(MPADecodeContext *s,

  1845.                           GranuleDef *g, 

  1846.                           int32_t *sb_samples,

  1847.                           int32_t *mdct_buf)

  1848. {

  1849.     int32_t *ptr, *win, *win1, *buf, *buf2, *out_ptr, *ptr1;

  1850.     int32_t in[6];

  1851.     int32_t out[36];

  1852.     int32_t out2[12];

  1853.     int i, j, k, mdct_long_end, v, sblimit;

  1854. 

  1855.     /* find last non zero block */

  1856.     ptr = g->sb_hybrid + 576;

  1857.     ptr1 = g->sb_hybrid + 2 * 18;

  1858.     while (ptr >= ptr1) {

  1859.         ptr -= 6;

  1860.         v = ptr[0] | ptr[1] | ptr[2] | ptr[3] | ptr[4] | ptr[5];

  1861.         if (v != 0)

  1862.             break;

  1863.     }

  1864.     sblimit = ((ptr - g->sb_hybrid) / 18) + 1;

  1865. 

  1866.     if (g->block_type == 2) {

  1867.         /* XXX: check for 8000 Hz */

  1868.         if (g->switch_point)

  1869.             mdct_long_end = 2;

  1870.         else

  1871.             mdct_long_end = 0;

  1872.     } else {

  1873.         mdct_long_end = sblimit;

  1874.     }

  1875. 

  1876.     buf = mdct_buf;

  1877.     ptr = g->sb_hybrid;

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

  1879.         imdct36(out, ptr);

  1880.         /* apply window & overlap with previous buffer */

  1881.         out_ptr = sb_samples + j;

  1882.         /* select window */

  1883.         if (g->switch_point && j < 2)

  1884.             win1 = mdct_win[0];

  1885.         else

  1886.             win1 = mdct_win[g->block_type];

  1887.         /* select frequency inversion */

  1888.         win = win1 + ((4 * 36) & -(j & 1));

  1889.         for(i=0;i<18;i++) {

  1890.             *out_ptr = MULL(out[i], win[i]) + buf[i];

  1891.             buf[i] = MULL(out[i + 18], win[i + 18]);

  1892.             out_ptr += SBLIMIT;

  1893.         }

  1894.         ptr += 18;

  1895.         buf += 18;

  1896.     }

  1897.     for(j=mdct_long_end;j<sblimit;j++) {

  1898.         for(i=0;i<6;i++) {

  1899.             out[i] = 0;

  1900.             out[6 + i] = 0;

  1901.             out[30+i] = 0;

  1902.         }

  1903.         /* select frequency inversion */

  1904.         win = mdct_win[2] + ((4 * 36) & -(j & 1));

  1905.         buf2 = out + 6;

  1906.         for(k=0;k<3;k++) {

  1907.             /* reorder input for short mdct */

  1908.             ptr1 = ptr + k;

  1909.             for(i=0;i<6;i++) {

  1910.                 in[i] = *ptr1;

  1911.                 ptr1 += 3;

  1912.             }

  1913.             imdct12(out2, in);

  1914.             /* apply 12 point window and do small overlap */

  1915.             for(i=0;i<6;i++) {

  1916.                 buf2[i] = MULL(out2[i], win[i]) + buf2[i];

  1917.                 buf2[i + 6] = MULL(out2[i + 6], win[i + 6]);

  1918.             }

  1919.             buf2 += 6;

  1920.         }

  1921.         /* overlap */

  1922.         out_ptr = sb_samples + j;

  1923.         for(i=0;i<18;i++) {

  1924.             *out_ptr = out[i] + buf[i];

  1925.             buf[i] = out[i + 18];

  1926.             out_ptr += SBLIMIT;

  1927.         }

  1928.         ptr += 18;

  1929.         buf += 18;

  1930.     }

  1931.     /* zero bands */

  1932.     for(j=sblimit;j<SBLIMIT;j++) {

  1933.         /* overlap */

  1934.         out_ptr = sb_samples + j;

  1935.         for(i=0;i<18;i++) {

  1936.             *out_ptr = buf[i];

  1937.             buf[i] = 0;

  1938.             out_ptr += SBLIMIT;

  1939.         }

  1940.         buf += 18;

  1941.     }

  1942. }

  1943. 

  1944. #if defined(DEBUG)

  1945. void sample_dump(int fnum, int32_t *tab, int n)

  1946. {

  1947.     static FILE *files[16], *f;

  1948.     char buf[512];

  1949.     int i;

  1950.     int32_t v;

  1951.     

  1952.     f = files[fnum];

  1953.     if (!f) {

  1954.         sprintf(buf, "/tmp/out%d.%s.pcm", 

  1955.                 fnum, 

  1956. #ifdef USE_HIGHPRECISION

  1957.                 "hp"

  1958. #else

  1959.                 "lp"

  1960. #endif

  1961.                 );

  1962.         f = fopen(buf, "w");

  1963.         if (!f)

  1964.             return;

  1965.         files[fnum] = f;

  1966.     }

  1967.     

  1968.     if (fnum == 0) {

  1969.         static int pos = 0;

  1970.         printf("pos=%d\n", pos);

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

  1972.             printf(" %0.4f", (double)tab[i] / FRAC_ONE);

  1973.             if ((i % 18) == 17)

  1974.                 printf("\n");

  1975.         }

  1976.         pos += n;

  1977.     }

  1978.     for(i=0;i<n;i++) {

  1979.         /* normalize to 23 frac bits */

  1980.         v = tab[i] << (23 - FRAC_BITS);

  1981.         fwrite(&v, 1, sizeof(int32_t), f);

  1982.     }

  1983. }

  1984. #endif

  1985. 

  1986. 

  1987. /* main layer3 decoding function */

  1988. static int mp_decode_layer3(MPADecodeContext *s)

  1989. {

  1990.     int nb_granules, main_data_begin, private_bits;

  1991.     int gr, ch, blocksplit_flag, i, j, k, n, bits_pos, bits_left;

  1992.     GranuleDef granules[2][2], *g;

  1993.     int16_t exponents[576];

  1994. 

  1995.     /* read side info */

  1996.     if (s->lsf) {

  1997.         main_data_begin = get_bits(&s->gb, 8);

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

  1999.             private_bits = get_bits(&s->gb, 2);

  2000.         else

  2001.             private_bits = get_bits(&s->gb, 1);

  2002.         nb_granules = 1;

  2003.     } else {

  2004.         main_data_begin = get_bits(&s->gb, 9);

  2005.         if (s->nb_channels == 2)

  2006.             private_bits = get_bits(&s->gb, 3);

  2007.         else

  2008.             private_bits = get_bits(&s->gb, 5);

  2009.         nb_granules = 2;

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

  2011.             granules[ch][0].scfsi = 0; /* all scale factors are transmitted */

  2012.             granules[ch][1].scfsi = get_bits(&s->gb, 4);

  2013.         }

  2014.     }

  2015.     

  2016.     for(gr=0;gr<nb_granules;gr++) {

  2017.         for(ch=0;ch<s->nb_channels;ch++) {

  2018.             dprintf("gr=%d ch=%d: side_info\n", gr, ch);

  2019.             g = &granules[ch][gr];

  2020.             g->part2_3_length = get_bits(&s->gb, 12);

  2021.             g->big_values = get_bits(&s->gb, 9);

  2022.             g->global_gain = get_bits(&s->gb, 8);

  2023.             /* if MS stereo only is selected, we precompute the

  2024.                1/sqrt(2) renormalization factor */

  2025.             if ((s->mode_ext & (MODE_EXT_MS_STEREO | MODE_EXT_I_STEREO)) == 

  2026.                 MODE_EXT_MS_STEREO)

  2027.                 g->global_gain -= 2;

  2028.             if (s->lsf)

  2029.                 g->scalefac_compress = get_bits(&s->gb, 9);

  2030.             else

  2031.                 g->scalefac_compress = get_bits(&s->gb, 4);

  2032.             blocksplit_flag = get_bits(&s->gb, 1);

  2033.             if (blocksplit_flag) {

  2034.                 g->block_type = get_bits(&s->gb, 2);

  2035.                 if (g->block_type == 0)

  2036.                     return -1;

  2037.                 g->switch_point = get_bits(&s->gb, 1);

  2038.                 for(i=0;i<2;i++)

  2039.                     g->table_select[i] = get_bits(&s->gb, 5);

  2040.                 for(i=0;i<3;i++) 

  2041.                     g->subblock_gain[i] = get_bits(&s->gb, 3);

  2042.                 /* compute huffman coded region sizes */

  2043.                 if (g->block_type == 2)

  2044.                     g->region_size[0] = (36 / 2);

  2045.                 else {

  2046.                     if (s->sample_rate_index <= 2) 

  2047.                         g->region_size[0] = (36 / 2);

  2048.                     else if (s->sample_rate_index != 8) 

  2049.                         g->region_size[0] = (54 / 2);

  2050.                     else

  2051.                         g->region_size[0] = (108 / 2);

  2052.                 }

  2053.                 g->region_size[1] = (576 / 2);

  2054.             } else {

  2055.                 int region_address1, region_address2, l;

  2056.                 g->block_type = 0;

  2057.                 g->switch_point = 0;

  2058.                 for(i=0;i<3;i++)

  2059.                     g->table_select[i] = get_bits(&s->gb, 5);

  2060.                 /* compute huffman coded region sizes */

  2061.                 region_address1 = get_bits(&s->gb, 4);

  2062.                 region_address2 = get_bits(&s->gb, 3);

  2063.                 dprintf("region1=%d region2=%d\n", 

  2064.                         region_address1, region_address2);

  2065.                 g->region_size[0] = 

  2066.                     band_index_long[s->sample_rate_index][region_address1 + 1] >> 1;

  2067.                 l = region_address1 + region_address2 + 2;

  2068.                 /* should not overflow */

  2069.                 if (l > 22)

  2070.                     l = 22;

  2071.                 g->region_size[1] = 

  2072.                     band_index_long[s->sample_rate_index][l] >> 1;

  2073.             }

  2074.             /* convert region offsets to region sizes and truncate

  2075.                size to big_values */

  2076.             g->region_size[2] = (576 / 2);

  2077.             j = 0;

  2078.             for(i=0;i<3;i++) {

  2079.                 k = g->region_size[i];

  2080.                 if (k > g->big_values)

  2081.                     k = g->big_values;

  2082.                 g->region_size[i] = k - j;

  2083.                 j = k;

  2084.             }

  2085. 

  2086.             /* compute band indexes */

  2087.             if (g->block_type == 2) {

  2088.                 if (g->switch_point) {

  2089.                     /* if switched mode, we handle the 36 first samples as

  2090.                        long blocks.  For 8000Hz, we handle the 48 first

  2091.                        exponents as long blocks (XXX: check this!) */

  2092.                     if (s->sample_rate_index <= 2)

  2093.                         g->long_end = 8;

  2094.                     else if (s->sample_rate_index != 8)

  2095.                         g->long_end = 6;

  2096.                     else

  2097.                         g->long_end = 4; /* 8000 Hz */

  2098.                     

  2099.                     if (s->sample_rate_index != 8)

  2100.                         g->short_start = 3;

  2101.                     else

  2102.                         g->short_start = 2; 

  2103.                 } else {

  2104.                     g->long_end = 0;

  2105.                     g->short_start = 0;

  2106.                 }

  2107.             } else {

  2108.                 g->short_start = 13;

  2109.                 g->long_end = 22;

  2110.             }

  2111.             

  2112.             g->preflag = 0;

  2113.             if (!s->lsf)

  2114.                 g->preflag = get_bits(&s->gb, 1);

  2115.             g->scalefac_scale = get_bits(&s->gb, 1);

  2116.             g->count1table_select = get_bits(&s->gb, 1);

  2117.             dprintf("block_type=%d switch_point=%d\n",

  2118.                     g->block_type, g->switch_point);

  2119.         }

  2120.     }

  2121. 

  2122.     /* now we get bits from the main_data_begin offset */

  2123.     dprintf("seekback: %d\n", main_data_begin);

  2124.     seek_to_maindata(s, main_data_begin);

  2125. 

  2126.     for(gr=0;gr<nb_granules;gr++) {

  2127.         for(ch=0;ch<s->nb_channels;ch++) {

  2128.             g = &granules[ch][gr];

  2129.             

  2130.             bits_pos = get_bits_count(&s->gb);

  2131.             

  2132.             if (!s->lsf) {

  2133.                 uint8_t *sc;

  2134.                 int slen, slen1, slen2;

  2135. 

  2136.                 /* MPEG1 scale factors */

  2137.                 slen1 = slen_table[0][g->scalefac_compress];

  2138.                 slen2 = slen_table[1][g->scalefac_compress];

  2139.                 dprintf("slen1=%d slen2=%d\n", slen1, slen2);

  2140.                 if (g->block_type == 2) {

  2141.                     n = g->switch_point ? 17 : 18;

  2142.                     j = 0;

  2143.                     for(i=0;i<n;i++)

  2144.                         g->scale_factors[j++] = get_bitsz(&s->gb, slen1);

  2145.                     for(i=0;i<18;i++)

  2146.                         g->scale_factors[j++] = get_bitsz(&s->gb, slen2);

  2147.                     for(i=0;i<3;i++)

  2148.                         g->scale_factors[j++] = 0;

  2149.                 } else {

  2150.                     sc = granules[ch][0].scale_factors;

  2151.                     j = 0;

  2152.                     for(k=0;k<4;k++) {

  2153.                         n = (k == 0 ? 6 : 5);

  2154.                         if ((g->scfsi & (0x8 >> k)) == 0) {

  2155.                             slen = (k < 2) ? slen1 : slen2;

  2156.                             for(i=0;i<n;i++)

  2157.                                 g->scale_factors[j++] = get_bitsz(&s->gb, slen);

  2158.                         } else {

  2159.                             /* simply copy from last granule */

  2160.                             for(i=0;i<n;i++) {

  2161.                                 g->scale_factors[j] = sc[j];

  2162.                                 j++;

  2163.                             }

  2164.                         }

  2165.                     }

  2166.                     g->scale_factors[j++] = 0;

  2167.                 }

  2168. #if defined(DEBUG)

  2169.                 {

  2170.                     printf("scfsi=%x gr=%d ch=%d scale_factors:\n", 

  2171.                            g->scfsi, gr, ch);

  2172.                     for(i=0;i<j;i++)

  2173.                         printf(" %d", g->scale_factors[i]);

  2174.                     printf("\n");

  2175.                 }

  2176. #endif

  2177.             } else {

  2178.                 int tindex, tindex2, slen[4], sl, sf;

  2179. 

  2180.                 /* LSF scale factors */

  2181.                 if (g->block_type == 2) {

  2182.                     tindex = g->switch_point ? 2 : 1;

  2183.                 } else {

  2184.                     tindex = 0;

  2185.                 }

  2186.                 sf = g->scalefac_compress;

  2187.                 if ((s->mode_ext & MODE_EXT_I_STEREO) && ch == 1) {

  2188.                     /* intensity stereo case */

  2189.                     sf >>= 1;

  2190.                     if (sf < 180) {

  2191.                         lsf_sf_expand(slen, sf, 6, 6, 0);

  2192.                         tindex2 = 3;

  2193.                     } else if (sf < 244) {

  2194.                         lsf_sf_expand(slen, sf - 180, 4, 4, 0);

  2195.                         tindex2 = 4;

  2196.                     } else {

  2197.                         lsf_sf_expand(slen, sf - 244, 3, 0, 0);

  2198.                         tindex2 = 5;

  2199.                     }

  2200.                 } else {

  2201.                     /* normal case */

  2202.                     if (sf < 400) {

  2203.                         lsf_sf_expand(slen, sf, 5, 4, 4);

  2204.                         tindex2 = 0;

  2205.                     } else if (sf < 500) {

  2206.                         lsf_sf_expand(slen, sf - 400, 5, 4, 0);

  2207.                         tindex2 = 1;

  2208.                     } else {

  2209.                         lsf_sf_expand(slen, sf - 500, 3, 0, 0);

  2210.                         tindex2 = 2;

  2211.                         g->preflag = 1;

  2212.                     }

  2213.                 }

  2214. 

  2215.                 j = 0;

  2216.                 for(k=0;k<4;k++) {

  2217.                     n = lsf_nsf_table[tindex2][tindex][k];

  2218.                     sl = slen[k];

  2219.                     for(i=0;i<n;i++)

  2220.                         g->scale_factors[j++] = get_bitsz(&s->gb, sl);

  2221.                 }

  2222.                 /* XXX: should compute exact size */

  2223.                 for(;j<40;j++)

  2224.                     g->scale_factors[j] = 0;

  2225. #if defined(DEBUG)

  2226.                 {

  2227.                     printf("gr=%d ch=%d scale_factors:\n", 

  2228.                            gr, ch);

  2229.                     for(i=0;i<40;i++)

  2230.                         printf(" %d", g->scale_factors[i]);

  2231.                     printf("\n");

  2232.                 }

  2233. #endif

  2234.             }

  2235. 

  2236.             exponents_from_scale_factors(s, g, exponents);

  2237. 

  2238.             /* read Huffman coded residue */

  2239.             if (huffman_decode(s, g, exponents,

  2240.                                bits_pos + g->part2_3_length) < 0)

  2241.                 return -1;

  2242. #if defined(DEBUG)

  2243.             sample_dump(0, g->sb_hybrid, 576);

  2244. #endif

  2245. 

  2246.             /* skip extension bits */

  2247.             bits_left = g->part2_3_length - (get_bits_count(&s->gb) - bits_pos);

  2248.             if (bits_left < 0) {

  2249.                 dprintf("bits_left=%d\n", bits_left);

  2250.                 return -1;

  2251.             }

  2252.             while (bits_left >= 16) {

  2253.                 skip_bits(&s->gb, 16);

  2254.                 bits_left -= 16;

  2255.             }

  2256.             if (bits_left > 0)

  2257.                 skip_bits(&s->gb, bits_left);

  2258.         } /* ch */

  2259. 

  2260.         if (s->nb_channels == 2)

  2261.             compute_stereo(s, &granules[0][gr], &granules[1][gr]);

  2262. 

  2263.         for(ch=0;ch<s->nb_channels;ch++) {

  2264.             g = &granules[ch][gr];

  2265. 

  2266.             reorder_block(s, g);

  2267. #if defined(DEBUG)

  2268.             sample_dump(0, g->sb_hybrid, 576);

  2269. #endif

  2270.             compute_antialias(s, g);

  2271. #if defined(DEBUG)

  2272.             sample_dump(1, g->sb_hybrid, 576);

  2273. #endif

  2274.             compute_imdct(s, g, &s->sb_samples[ch][18 * gr][0], s->mdct_buf[ch]); 

  2275. #if defined(DEBUG)

  2276.             sample_dump(2, &s->sb_samples[ch][18 * gr][0], 576);

  2277. #endif

  2278.         }

  2279.     } /* gr */

  2280.     return nb_granules * 18;

  2281. }

  2282. 

  2283. static int mp_decode_frame(MPADecodeContext *s, 

  2284.                            short *samples)

  2285. {

  2286.     int i, nb_frames, ch;

  2287.     short *samples_ptr;

  2288. 

  2289.     init_get_bits(&s->gb, s->inbuf + HEADER_SIZE, 

  2290.                   (s->inbuf_ptr - s->inbuf - HEADER_SIZE)*8);

  2291.     

  2292.     /* skip error protection field */

  2293.     if (s->error_protection)

  2294.         get_bits(&s->gb, 16);

  2295. 

  2296.     dprintf("frame %d:\n", s->frame_count);

  2297.     switch(s->layer) {

  2298.     case 1:

  2299.         nb_frames = mp_decode_layer1(s);

  2300.         break;

  2301.     case 2:

  2302.         nb_frames = mp_decode_layer2(s);

  2303.         break;

  2304.     case 3:

  2305.     default:

  2306.         nb_frames = mp_decode_layer3(s);

  2307.         break;

  2308.     }

  2309. #if defined(DEBUG)

  2310.     for(i=0;i<nb_frames;i++) {

  2311.         for(ch=0;ch<s->nb_channels;ch++) {

  2312.             int j;

  2313.             printf("%d-%d:", i, ch);

  2314.             for(j=0;j<SBLIMIT;j++)

  2315.                 printf(" %0.6f", (double)s->sb_samples[ch][i][j] / FRAC_ONE);

  2316.             printf("\n");

  2317.         }

  2318.     }

  2319. #endif

  2320.     /* apply the synthesis filter */

  2321.     for(ch=0;ch<s->nb_channels;ch++) {

  2322.         samples_ptr = samples + ch;

  2323.         for(i=0;i<nb_frames;i++) {

  2324.             synth_filter(s, ch, samples_ptr, s->nb_channels,

  2325.                          s->sb_samples[ch][i]);

  2326.             samples_ptr += 32 * s->nb_channels;

  2327.         }

  2328.     }

  2329. #ifdef DEBUG

  2330.     s->frame_count++;        

  2331. #endif

  2332.     return nb_frames * 32 * sizeof(short) * s->nb_channels;

  2333. }

  2334. 

  2335. static int decode_frame(AVCodecContext * avctx,

  2336. 			void *data, int *data_size,

  2337. 			uint8_t * buf, int buf_size)

  2338. {

  2339.     MPADecodeContext *s = avctx->priv_data;

  2340.     uint32_t header;

  2341.     uint8_t *buf_ptr;

  2342.     int len, out_size;

  2343.     short *out_samples = data;

  2344. 

  2345.     *data_size = 0;

  2346.     buf_ptr = buf;

  2347.     while (buf_size > 0) {

  2348. 	len = s->inbuf_ptr - s->inbuf;

  2349. 	if (s->frame_size == 0) {

  2350.             /* special case for next header for first frame in free

  2351.                format case (XXX: find a simpler method) */

  2352.             if (s->free_format_next_header != 0) {

  2353.                 s->inbuf[0] = s->free_format_next_header >> 24;

  2354.                 s->inbuf[1] = s->free_format_next_header >> 16;

  2355.                 s->inbuf[2] = s->free_format_next_header >> 8;

  2356.                 s->inbuf[3] = s->free_format_next_header;

  2357.                 s->inbuf_ptr = s->inbuf + 4;

  2358.                 s->free_format_next_header = 0;

  2359.                 goto got_header;

  2360.             }

  2361. 	    /* no header seen : find one. We need at least HEADER_SIZE

  2362.                bytes to parse it */

  2363. 	    len = HEADER_SIZE - len;

  2364. 	    if (len > buf_size)

  2365. 		len = buf_size;

  2366. 	    if (len > 0) {

  2367. 		memcpy(s->inbuf_ptr, buf_ptr, len);

  2368. 		buf_ptr += len;

  2369. 		buf_size -= len;

  2370. 		s->inbuf_ptr += len;

  2371. 	    }

  2372. 	    if ((s->inbuf_ptr - s->inbuf) >= HEADER_SIZE) {

  2373.             got_header:

  2374. 		header = (s->inbuf[0] << 24) | (s->inbuf[1] << 16) |

  2375. 		    (s->inbuf[2] << 8) | s->inbuf[3];

  2376. 

  2377. 		if (check_header(header) < 0) {

  2378. 		    /* no sync found : move by one byte (inefficient, but simple!) */

  2379. 		    memcpy(s->inbuf, s->inbuf + 1, s->inbuf_ptr - s->inbuf - 1);

  2380. 		    s->inbuf_ptr--;

  2381.                     dprintf("skip %x\n", header);

  2382.                     /* reset free format frame size to give a chance

  2383.                        to get a new bitrate */

  2384.                     s->free_format_frame_size = 0;

  2385. 		} else {

  2386. 		    if (decode_header(s, header) == 1) {

  2387.                         /* free format: prepare to compute frame size */

  2388. 			s->frame_size = -1;

  2389.                     }

  2390.                     /* update codec info */

  2391.                     avctx->sample_rate = s->sample_rate;

  2392.                     avctx->channels = s->nb_channels;

  2393.                     avctx->bit_rate = s->bit_rate;

  2394.                     avctx->frame_size = s->frame_size;

  2395. 		}

  2396. 	    }

  2397.         } else if (s->frame_size == -1) {

  2398.             /* free format : find next sync to compute frame size */

  2399. 	    len = MPA_MAX_CODED_FRAME_SIZE - len;

  2400. 	    if (len > buf_size)

  2401. 		len = buf_size;

  2402.             if (len == 0) {

  2403. 		/* frame too long: resync */

  2404.                 s->frame_size = 0;

  2405. 		memcpy(s->inbuf, s->inbuf + 1, s->inbuf_ptr - s->inbuf - 1);

  2406. 		s->inbuf_ptr--;

  2407.             } else {

  2408.                 uint8_t *p, *pend;

  2409.                 uint32_t header1;

  2410.                 int padding;

  2411. 

  2412.                 memcpy(s->inbuf_ptr, buf_ptr, len);

  2413.                 /* check for header */

  2414.                 p = s->inbuf_ptr - 3;

  2415.                 pend = s->inbuf_ptr + len - 4;

  2416.                 while (p <= pend) {

  2417.                     header = (p[0] << 24) | (p[1] << 16) |

  2418.                         (p[2] << 8) | p[3];

  2419.                     header1 = (s->inbuf[0] << 24) | (s->inbuf[1] << 16) |

  2420.                         (s->inbuf[2] << 8) | s->inbuf[3];

  2421.                     /* check with high probability that we have a

  2422.                        valid header */

  2423.                     if ((header & SAME_HEADER_MASK) ==

  2424.                         (header1 & SAME_HEADER_MASK)) {

  2425.                         /* header found: update pointers */

  2426.                         len = (p + 4) - s->inbuf_ptr;

  2427.                         buf_ptr += len;

  2428.                         buf_size -= len;

  2429.                         s->inbuf_ptr = p;

  2430.                         /* compute frame size */

  2431.                         s->free_format_next_header = header;

  2432.                         s->free_format_frame_size = s->inbuf_ptr - s->inbuf;

  2433.                         padding = (header1 >> 9) & 1;

  2434.                         if (s->layer == 1)

  2435.                             s->free_format_frame_size -= padding * 4;

  2436.                         else

  2437.                             s->free_format_frame_size -= padding;

  2438.                         dprintf("free frame size=%d padding=%d\n", 

  2439.                                 s->free_format_frame_size, padding);

  2440.                         decode_header(s, header1);

  2441.                         goto next_data;

  2442.                     }

  2443.                     p++;

  2444.                 }

  2445.                 /* not found: simply increase pointers */

  2446.                 buf_ptr += len;

  2447.                 s->inbuf_ptr += len;

  2448.                 buf_size -= len;

  2449.             }

  2450. 	} else if (len < s->frame_size) {

  2451.             if (s->frame_size > MPA_MAX_CODED_FRAME_SIZE)

  2452.                 s->frame_size = MPA_MAX_CODED_FRAME_SIZE;

  2453. 	    len = s->frame_size - len;

  2454. 	    if (len > buf_size)

  2455. 		len = buf_size;

  2456. 	    memcpy(s->inbuf_ptr, buf_ptr, len);

  2457. 	    buf_ptr += len;

  2458. 	    s->inbuf_ptr += len;

  2459. 	    buf_size -= len;

  2460. 	} else {

  2461.             out_size = mp_decode_frame(s, out_samples);

  2462. 	    s->inbuf_ptr = s->inbuf;

  2463. 	    s->frame_size = 0;

  2464. 	    *data_size = out_size;

  2465. 	    break;

  2466. 	}

  2467.     next_data:

  2468. 	;

  2469.     }

  2470.     return buf_ptr - buf;

  2471. }

  2472. 

  2473. AVCodec mp2_decoder =

  2474. {

  2475.     "mp2",

  2476.     CODEC_TYPE_AUDIO,

  2477.     CODEC_ID_MP2,

  2478.     sizeof(MPADecodeContext),

  2479.     decode_init,

  2480.     NULL,

  2481.     NULL,

  2482.     decode_frame,

  2483. };

  2484. 

  2485. AVCodec mp3_decoder =

  2486. {

  2487.     "mp3",

  2488.     CODEC_TYPE_AUDIO,

  2489.     CODEC_ID_MP3LAME,

  2490.     sizeof(MPADecodeContext),

  2491.     decode_init,

  2492.     NULL,

  2493.     NULL,

  2494.     decode_frame,

  2495. };

  2496. 

  2497. #undef C1

  2498. #undef C2

  2499. #undef C3

  2500. #undef C4

  2501. #undef C5

  2502. #undef C6

  2503. #undef C7

  2504. #undef C8

  2505. #undef FRAC_BITS

  2506. #undef HEADER_SIZE