## ffmpeg / libavcodec / mpegaudiodec.c @ 05f361f0

History | View | Annotate | Download (72.1 KB)

1 | de6d9b64 | Fabrice Bellard | ```
/*
``` |
---|---|---|---|

2 | ```
* MPEG Audio decoder
``` |
||

3 | ```
* Copyright (c) 2001 Gerard Lantau.
``` |
||

4 | ```
*
``` |
||

5 | ```
* This program is free software; you can redistribute it and/or modify
``` |
||

6 | ```
* it under the terms of the GNU General Public License as published by
``` |
||

7 | ```
* the Free Software Foundation; either version 2 of the License, or
``` |
||

8 | ```
* (at your option) any later version.
``` |
||

9 | ```
*
``` |
||

10 | ```
* This program 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
``` |
||

13 | ```
* GNU General Public License for more details.
``` |
||

14 | ```
*
``` |
||

15 | ```
* You should have received a copy of the GNU General Public License
``` |
||

16 | ```
* along with this program; if not, write to the Free Software
``` |
||

17 | ```
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
``` |
||

18 | ```
*/
``` |
||

19 | 239c2f4c | Fabrice Bellard | ```
//#define DEBUG
``` |

20 | de6d9b64 | Fabrice Bellard | #include "avcodec.h" |

21 | 239c2f4c | Fabrice Bellard | #include <math.h> |

22 | #include "mpegaudio.h" |
||

23 | de6d9b64 | Fabrice Bellard | |

24 | ```
/*
``` |
||

25 | 239c2f4c | Fabrice Bellard | ```
* TODO:
``` |

26 | ```
* - in low precision mode, use more 16 bit multiplies in synth filter
``` |
||

27 | ```
* - test lsf / mpeg25 extensively.
``` |
||

28 | de6d9b64 | Fabrice Bellard | ```
*/
``` |

29 | |||

30 | 239c2f4c | Fabrice Bellard | ```
/* define USE_HIGHPRECISION to have a bit exact (but slower) mpeg
``` |

31 | ```
audio decoder */
``` |
||

32 | ```
//#define USE_HIGHPRECISION
``` |
||

33 | |||

34 | ```
#ifdef USE_HIGHPRECISION
``` |
||

35 | #define FRAC_BITS 23 /* fractional bits for sb_samples and dct */ |
||

36 | #define WFRAC_BITS 16 /* fractional bits for window */ |
||

37 | ```
#else
``` |
||

38 | #define FRAC_BITS 15 /* fractional bits for sb_samples and dct */ |
||

39 | #define WFRAC_BITS 14 /* fractional bits for window */ |
||

40 | ```
#endif
``` |
||

41 | |||

42 | #define FRAC_ONE (1 << FRAC_BITS) |
||

43 | |||

44 | ```
#define MULL(a,b) (((INT64)(a) * (INT64)(b)) >> FRAC_BITS)
``` |
||

45 | ```
#define MUL64(a,b) ((INT64)(a) * (INT64)(b))
``` |
||

46 | #define FIX(a) ((int)((a) * FRAC_ONE)) |
||

47 | ```
/* WARNING: only correct for posititive numbers */
``` |
||

48 | #define FIXR(a) ((int)((a) * FRAC_ONE + 0.5)) |
||

49 | #define FRAC_RND(a) (((a) + (FRAC_ONE/2)) >> FRAC_BITS) |
||

50 | |||

51 | #if FRAC_BITS <= 15 |
||

52 | ```
typedef INT16 MPA_INT;
``` |
||

53 | ```
#else
``` |
||

54 | ```
typedef INT32 MPA_INT;
``` |
||

55 | ```
#endif
``` |
||

56 | |||

57 | ```
/****************/
``` |
||

58 | |||

59 | de6d9b64 | Fabrice Bellard | #define HEADER_SIZE 4 |

60 | #define BACKSTEP_SIZE 512 |
||

61 | |||

62 | typedef struct MPADecodeContext { |
||

63 | 239c2f4c | Fabrice Bellard | UINT8 inbuf1[2][MPA_MAX_CODED_FRAME_SIZE + BACKSTEP_SIZE]; /* input buffer */ |

64 | de6d9b64 | Fabrice Bellard | ```
int inbuf_index;
``` |

65 | UINT8 *inbuf_ptr, *inbuf; |
||

66 | ```
int frame_size;
``` |
||

67 | 239c2f4c | Fabrice Bellard | int free_format_frame_size; /* frame size in case of free format |

68 | ```
(zero if currently unknown) */
``` |
||

69 | ```
/* next header (used in free format parsing) */
``` |
||

70 | UINT32 free_format_next_header; |
||

71 | de6d9b64 | Fabrice Bellard | ```
int error_protection;
``` |

72 | ```
int layer;
``` |
||

73 | ```
int sample_rate;
``` |
||

74 | 239c2f4c | Fabrice Bellard | int sample_rate_index; /* between 0 and 8 */ |

75 | de6d9b64 | Fabrice Bellard | ```
int bit_rate;
``` |

76 | ```
int old_frame_size;
``` |
||

77 | GetBitContext gb; |
||

78 | 239c2f4c | Fabrice Bellard | ```
int nb_channels;
``` |

79 | ```
int mode;
``` |
||

80 | ```
int mode_ext;
``` |
||

81 | ```
int lsf;
``` |
||

82 | MPA_INT synth_buf[MPA_MAX_CHANNELS][512 * 2]; |
||

83 | ```
int synth_buf_offset[MPA_MAX_CHANNELS];
``` |
||

84 | ```
INT32 sb_samples[MPA_MAX_CHANNELS][36][SBLIMIT];
``` |
||

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

86 | ```
#ifdef DEBUG
``` |
||

87 | ```
int frame_count;
``` |
||

88 | ```
#endif
``` |
||

89 | de6d9b64 | Fabrice Bellard | } MPADecodeContext; |

90 | |||

91 | 239c2f4c | Fabrice Bellard | ```
/* layer 3 "granule" */
``` |

92 | typedef struct GranuleDef { |
||

93 | UINT8 scfsi; |
||

94 | ```
int part2_3_length;
``` |
||

95 | ```
int big_values;
``` |
||

96 | ```
int global_gain;
``` |
||

97 | ```
int scalefac_compress;
``` |
||

98 | UINT8 block_type; |
||

99 | UINT8 switch_point; |
||

100 | int table_select[3]; |
||

101 | int subblock_gain[3]; |
||

102 | UINT8 scalefac_scale; |
||

103 | UINT8 count1table_select; |
||

104 | int region_size[3]; /* number of huffman codes in each region */ |
||

105 | ```
int preflag;
``` |
||

106 | int short_start, long_end; /* long/short band indexes */ |
||

107 | ```
UINT8 scale_factors[40];
``` |
||

108 | INT32 sb_hybrid[SBLIMIT * 18]; /* 576 samples */ |
||

109 | } GranuleDef; |
||

110 | de6d9b64 | Fabrice Bellard | |

111 | 239c2f4c | Fabrice Bellard | #define MODE_EXT_MS_STEREO 2 |

112 | #define MODE_EXT_I_STEREO 1 |
||

113 | |||

114 | ```
/* layer 3 huffman tables */
``` |
||

115 | typedef struct HuffTable { |
||

116 | ```
int xsize;
``` |
||

117 | ```
const UINT8 *bits;
``` |
||

118 | ```
const UINT16 *codes;
``` |
||

119 | } HuffTable; |
||

120 | |||

121 | #include "mpegaudiodectab.h" |
||

122 | |||

123 | ```
/* vlc structure for decoding layer 3 huffman tables */
``` |
||

124 | static VLC huff_vlc[16]; |
||

125 | static UINT8 *huff_code_table[16]; |
||

126 | static VLC huff_quad_vlc[2]; |
||

127 | ```
/* computed from band_size_long */
``` |
||

128 | static UINT16 band_index_long[9][23]; |
||

129 | ```
/* XXX: free when all decoders are closed */
``` |
||

130 | #define TABLE_4_3_SIZE (8191 + 16) |
||

131 | ```
static UINT8 *table_4_3_exp;
``` |
||

132 | #if FRAC_BITS <= 15 |
||

133 | ```
static UINT16 *table_4_3_value;
``` |
||

134 | ```
#else
``` |
||

135 | ```
static UINT32 *table_4_3_value;
``` |
||

136 | ```
#endif
``` |
||

137 | ```
/* intensity stereo coef table */
``` |
||

138 | static INT32 is_table[2][16]; |
||

139 | static INT32 is_table_lsf[2][2][16]; |
||

140 | static INT32 csa_table[8][2]; |
||

141 | static INT32 mdct_win[8][36]; |
||

142 | |||

143 | ```
/* lower 2 bits: modulo 3, higher bits: shift */
``` |
||

144 | static UINT16 scale_factor_modshift[64]; |
||

145 | ```
/* [i][j]: 2^(-j/3) * FRAC_ONE * 2^(i+2) / (2^(i+2) - 1) */
``` |
||

146 | static INT32 scale_factor_mult[15][3]; |
||

147 | ```
/* mult table for layer 2 group quantization */
``` |
||

148 | |||

149 | ```
#define SCALE_GEN(v) \
``` |
||

150 | { FIXR(1.0 * (v)), FIXR(0.7937005259 * (v)), FIXR(0.6299605249 * (v)) } |
||

151 | |||

152 | static INT32 scale_factor_mult2[3][3] = { |
||

153 | SCALE_GEN(1.0 / 3.0), /* 3 steps */ |
||

154 | SCALE_GEN(1.0 / 5.0), /* 5 steps */ |
||

155 | SCALE_GEN(1.0 / 9.0), /* 9 steps */ |
||

156 | }; |
||

157 | |||

158 | ```
/* 2^(n/4) */
``` |
||

159 | static UINT32 scale_factor_mult3[4] = { |
||

160 | FIXR(1.0), |
||

161 | FIXR(1.18920711500272106671), |
||

162 | FIXR(1.41421356237309504880), |
||

163 | FIXR(1.68179283050742908605), |
||

164 | de6d9b64 | Fabrice Bellard | }; |

165 | |||

166 | 239c2f4c | Fabrice Bellard | static MPA_INT window[512]; |

167 | |||

168 | ```
/* layer 1 unscaling */
``` |
||

169 | ```
/* n = number of bits of the mantissa minus 1 */
``` |
||

170 | static inline int l1_unscale(int n, int mant, int scale_factor) |
||

171 | { |
||

172 | ```
int shift, mod;
``` |
||

173 | INT64 val; |
||

174 | |||

175 | shift = scale_factor_modshift[scale_factor]; |
||

176 | ```
mod = shift & 3;
``` |
||

177 | ```
shift >>= 2;
``` |
||

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

179 | shift += n; |
||

180 | return (int)((val + (1 << (shift - 1))) >> shift); |
||

181 | } |
||

182 | |||

183 | static inline int l2_unscale_group(int steps, int mant, int scale_factor) |
||

184 | { |
||

185 | ```
int shift, mod, val;
``` |
||

186 | |||

187 | shift = scale_factor_modshift[scale_factor]; |
||

188 | ```
mod = shift & 3;
``` |
||

189 | ```
shift >>= 2;
``` |
||

190 | ```
/* XXX: store the result directly */
``` |
||

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

192 | return (val + (1 << (shift - 1))) >> shift; |
||

193 | } |
||

194 | |||

195 | ```
/* compute value^(4/3) * 2^(exponent/4). It normalized to FRAC_BITS */
``` |
||

196 | static inline int l3_unscale(int value, int exponent) |
||

197 | { |
||

198 | #if FRAC_BITS <= 15 |
||

199 | unsigned int m; |
||

200 | ```
#else
``` |
||

201 | UINT64 m; |
||

202 | ```
#endif
``` |
||

203 | ```
int e;
``` |
||

204 | |||

205 | e = table_4_3_exp[value]; |
||

206 | ```
e += (exponent >> 2);
``` |
||

207 | e = FRAC_BITS - e; |
||

208 | #if FRAC_BITS <= 15 |
||

209 | if (e > 31) |
||

210 | ```
e = 31;
``` |
||

211 | ```
#endif
``` |
||

212 | m = table_4_3_value[value]; |
||

213 | #if FRAC_BITS <= 15 |
||

214 | ```
m = (m * scale_factor_mult3[exponent & 3]);
``` |
||

215 | m = (m + (1 << (e-1))) >> e; |
||

216 | ```
return m;
``` |
||

217 | ```
#else
``` |
||

218 | ```
m = MUL64(m, scale_factor_mult3[exponent & 3]);
``` |
||

219 | m = (m + (UINT64_C(1) << (e-1))) >> e; |
||

220 | ```
return m;
``` |
||

221 | ```
#endif
``` |
||

222 | } |
||

223 | |||

224 | de6d9b64 | Fabrice Bellard | |

225 | static int decode_init(AVCodecContext * avctx) |
||

226 | { |
||

227 | MPADecodeContext *s = avctx->priv_data; |
||

228 | static int init; |
||

229 | 239c2f4c | Fabrice Bellard | ```
int i, j, k;
``` |

230 | de6d9b64 | Fabrice Bellard | |

231 | ```
if(!init) {
``` |
||

232 | 239c2f4c | Fabrice Bellard | ```
/* scale factors table for layer 1/2 */
``` |

233 | for(i=0;i<64;i++) { |
||

234 | ```
int shift, mod;
``` |
||

235 | ```
/* 1.0 (i = 3) is normalized to 2 ^ FRAC_BITS */
``` |
||

236 | shift = (i / 3) - 1; |
||

237 | ```
mod = i % 3;
``` |
||

238 | #if FRAC_BITS <= 15 |
||

239 | if (shift > 31) |
||

240 | ```
shift = 31;
``` |
||

241 | ```
#endif
``` |
||

242 | ```
scale_factor_modshift[i] = mod | (shift << 2);
``` |
||

243 | } |
||

244 | |||

245 | ```
/* scale factor multiply for layer 1 */
``` |
||

246 | for(i=0;i<15;i++) { |
||

247 | ```
int n, norm;
``` |
||

248 | ```
n = i + 2;
``` |
||

249 | norm = ((INT64_C(1) << n) * FRAC_ONE) / ((1 << n) - 1); |
||

250 | scale_factor_mult[i][0] = MULL(FIXR(1.0), norm); |
||

251 | scale_factor_mult[i][1] = MULL(FIXR(0.7937005259), norm); |
||

252 | scale_factor_mult[i][2] = MULL(FIXR(0.6299605249), norm); |
||

253 | ```
dprintf("%d: norm=%x s=%x %x %x\n",
``` |
||

254 | i, norm, |
||

255 | ```
scale_factor_mult[i][0],
``` |
||

256 | ```
scale_factor_mult[i][1],
``` |
||

257 | ```
scale_factor_mult[i][2]);
``` |
||

258 | } |
||

259 | |||

260 | ```
/* window */
``` |
||

261 | ```
/* max = 18760, max sum over all 16 coefs : 44736 */
``` |
||

262 | for(i=0;i<257;i++) { |
||

263 | ```
int v;
``` |
||

264 | v = mpa_enwindow[i]; |
||

265 | #if WFRAC_BITS < 16 |
||

266 | v = (v + (1 << (16 - WFRAC_BITS - 1))) >> (16 - WFRAC_BITS); |
||

267 | ```
#endif
``` |
||

268 | window[i] = v; |
||

269 | if ((i & 63) != 0) |
||

270 | v = -v; |
||

271 | if (i != 0) |
||

272 | ```
window[512 - i] = v;
``` |
||

273 | } |
||

274 | |||

275 | ```
/* huffman decode tables */
``` |
||

276 | huff_code_table[0] = NULL; |
||

277 | for(i=1;i<16;i++) { |
||

278 | ```
const HuffTable *h = &mpa_huff_tables[i];
``` |
||

279 | ```
int xsize, n, x, y;
``` |
||

280 | UINT8 *code_table; |
||

281 | |||

282 | xsize = h->xsize; |
||

283 | n = xsize * xsize; |
||

284 | ```
/* XXX: fail test */
``` |
||

285 | ```
init_vlc(&huff_vlc[i], 8, n,
``` |
||

286 | h->bits, 1, 1, h->codes, 2, 2); |
||

287 | |||

288 | code_table = av_mallocz(n); |
||

289 | ```
j = 0;
``` |
||

290 | for(x=0;x<xsize;x++) { |
||

291 | for(y=0;y<xsize;y++) |
||

292 | ```
code_table[j++] = (x << 4) | y;
``` |
||

293 | } |
||

294 | huff_code_table[i] = code_table; |
||

295 | } |
||

296 | for(i=0;i<2;i++) { |
||

297 | init_vlc(&huff_quad_vlc[i], i == 0 ? 7 : 4, 16, |
||

298 | mpa_quad_bits[i], 1, 1, mpa_quad_codes[i], 1, 1); |
||

299 | } |
||

300 | |||

301 | for(i=0;i<9;i++) { |
||

302 | ```
k = 0;
``` |
||

303 | for(j=0;j<22;j++) { |
||

304 | band_index_long[i][j] = k; |
||

305 | k += band_size_long[i][j]; |
||

306 | } |
||

307 | ```
band_index_long[i][22] = k;
``` |
||

308 | } |
||

309 | |||

310 | ```
/* compute n ^ (4/3) and store it in mantissa/exp format */
``` |
||

311 | table_4_3_exp = av_mallocz(TABLE_4_3_SIZE * |
||

312 | sizeof(table_4_3_exp[0])); |
||

313 | ```
if (!table_4_3_exp)
``` |
||

314 | return -1; |
||

315 | table_4_3_value = av_mallocz(TABLE_4_3_SIZE * |
||

316 | sizeof(table_4_3_value[0])); |
||

317 | ```
if (!table_4_3_value) {
``` |
||

318 | free(table_4_3_exp); |
||

319 | return -1; |
||

320 | } |
||

321 | |||

322 | for(i=1;i<TABLE_4_3_SIZE;i++) { |
||

323 | ```
double f, fm;
``` |
||

324 | ```
int e, m;
``` |
||

325 | f = pow((double)i, 4.0 / 3.0); |
||

326 | fm = frexp(f, &e); |
||

327 | ```
m = FIXR(2 * fm);
``` |
||

328 | #if FRAC_BITS <= 15 |
||

329 | if ((unsigned short)m != m) |
||

330 | ```
m = 65535;
``` |
||

331 | ```
#endif
``` |
||

332 | ```
/* normalized to FRAC_BITS */
``` |
||

333 | table_4_3_value[i] = m; |
||

334 | ```
table_4_3_exp[i] = e - 1;
``` |
||

335 | } |
||

336 | |||

337 | |||

338 | for(i=0;i<7;i++) { |
||

339 | ```
float f;
``` |
||

340 | ```
int v;
``` |
||

341 | if (i != 6) { |
||

342 | f = tan((double)i * M_PI / 12.0); |
||

343 | v = FIXR(f / (1.0 + f)); |
||

344 | ```
} else {
``` |
||

345 | v = FIXR(1.0); |
||

346 | } |
||

347 | ```
is_table[0][i] = v;
``` |
||

348 | is_table[1][6 - i] = v; |
||

349 | } |
||

350 | ```
/* invalid values */
``` |
||

351 | for(i=7;i<16;i++) |
||

352 | is_table[0][i] = is_table[1][i] = 0.0; |
||

353 | |||

354 | for(i=0;i<16;i++) { |
||

355 | ```
double f;
``` |
||

356 | ```
int e, k;
``` |
||

357 | |||

358 | for(j=0;j<2;j++) { |
||

359 | e = -(j + 1) * ((i + 1) >> 1); |
||

360 | f = pow(2.0, e / 4.0); |
||

361 | ```
k = i & 1;
``` |
||

362 | ```
is_table_lsf[j][k ^ 1][i] = FIXR(f);
``` |
||

363 | is_table_lsf[j][k][i] = FIXR(1.0); |
||

364 | ```
dprintf("is_table_lsf %d %d: %x %x\n",
``` |
||

365 | i, j, is_table_lsf[j][0][i], is_table_lsf[j][1][i]); |
||

366 | } |
||

367 | } |
||

368 | |||

369 | for(i=0;i<8;i++) { |
||

370 | ```
float ci, cs, ca;
``` |
||

371 | ci = ci_table[i]; |
||

372 | cs = 1.0 / sqrt(1.0 + ci * ci); |
||

373 | ca = cs * ci; |
||

374 | ```
csa_table[i][0] = FIX(cs);
``` |
||

375 | ```
csa_table[i][1] = FIX(ca);
``` |
||

376 | } |
||

377 | |||

378 | ```
/* compute mdct windows */
``` |
||

379 | for(i=0;i<36;i++) { |
||

380 | ```
int v;
``` |
||

381 | v = FIXR(sin(M_PI * (i + 0.5) / 36.0)); |
||

382 | ```
mdct_win[0][i] = v;
``` |
||

383 | ```
mdct_win[1][i] = v;
``` |
||

384 | ```
mdct_win[3][i] = v;
``` |
||

385 | } |
||

386 | for(i=0;i<6;i++) { |
||

387 | mdct_win[1][18 + i] = FIXR(1.0); |
||

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

389 | mdct_win[1][30 + i] = FIXR(0.0); |
||

390 | |||

391 | mdct_win[3][i] = FIXR(0.0); |
||

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

393 | mdct_win[3][12 + i] = FIXR(1.0); |
||

394 | } |
||

395 | |||

396 | for(i=0;i<12;i++) |
||

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

398 | |||

399 | ```
/* NOTE: we do frequency inversion adter the MDCT by changing
``` |
||

400 | ```
the sign of the right window coefs */
``` |
||

401 | for(j=0;j<4;j++) { |
||

402 | for(i=0;i<36;i+=2) { |
||

403 | ```
mdct_win[j + 4][i] = mdct_win[j][i];
``` |
||

404 | mdct_win[j + 4][i + 1] = -mdct_win[j][i + 1]; |
||

405 | } |
||

406 | } |
||

407 | |||

408 | ```
#if defined(DEBUG)
``` |
||

409 | for(j=0;j<8;j++) { |
||

410 | ```
printf("win%d=\n", j);
``` |
||

411 | for(i=0;i<36;i++) |
||

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

413 | ```
printf("\n");
``` |
||

414 | } |
||

415 | ```
#endif
``` |
||

416 | de6d9b64 | Fabrice Bellard | ```
init = 1;
``` |

417 | } |
||

418 | |||

419 | ```
s->inbuf_index = 0;
``` |
||

420 | s->inbuf = &s->inbuf1[s->inbuf_index][BACKSTEP_SIZE]; |
||

421 | s->inbuf_ptr = s->inbuf; |
||

422 | 239c2f4c | Fabrice Bellard | ```
#ifdef DEBUG
``` |

423 | ```
s->frame_count = 0;
``` |
||

424 | ```
#endif
``` |
||

425 | de6d9b64 | Fabrice Bellard | return 0; |

426 | } |
||

427 | |||

428 | 239c2f4c | Fabrice Bellard | ```
/* tab[i][j] = 1.0 / (2.0 * cos(pi*(2*k+1) / 2^(6 - j))) */;
``` |

429 | |||

430 | ```
/* cos(i*pi/64) */
``` |
||

431 | |||

432 | #define COS0_0 FIXR(0.50060299823519630134) |
||

433 | #define COS0_1 FIXR(0.50547095989754365998) |
||

434 | #define COS0_2 FIXR(0.51544730992262454697) |
||

435 | #define COS0_3 FIXR(0.53104259108978417447) |
||

436 | #define COS0_4 FIXR(0.55310389603444452782) |
||

437 | #define COS0_5 FIXR(0.58293496820613387367) |
||

438 | #define COS0_6 FIXR(0.62250412303566481615) |
||

439 | #define COS0_7 FIXR(0.67480834145500574602) |
||

440 | #define COS0_8 FIXR(0.74453627100229844977) |
||

441 | #define COS0_9 FIXR(0.83934964541552703873) |
||

442 | #define COS0_10 FIXR(0.97256823786196069369) |
||

443 | #define COS0_11 FIXR(1.16943993343288495515) |
||

444 | #define COS0_12 FIXR(1.48416461631416627724) |
||

445 | #define COS0_13 FIXR(2.05778100995341155085) |
||

446 | #define COS0_14 FIXR(3.40760841846871878570) |
||

447 | #define COS0_15 FIXR(10.19000812354805681150) |
||

448 | |||

449 | #define COS1_0 FIXR(0.50241928618815570551) |
||

450 | #define COS1_1 FIXR(0.52249861493968888062) |
||

451 | #define COS1_2 FIXR(0.56694403481635770368) |
||

452 | #define COS1_3 FIXR(0.64682178335999012954) |
||

453 | #define COS1_4 FIXR(0.78815462345125022473) |
||

454 | #define COS1_5 FIXR(1.06067768599034747134) |
||

455 | #define COS1_6 FIXR(1.72244709823833392782) |
||

456 | #define COS1_7 FIXR(5.10114861868916385802) |
||

457 | |||

458 | #define COS2_0 FIXR(0.50979557910415916894) |
||

459 | #define COS2_1 FIXR(0.60134488693504528054) |
||

460 | #define COS2_2 FIXR(0.89997622313641570463) |
||

461 | #define COS2_3 FIXR(2.56291544774150617881) |
||

462 | |||

463 | #define COS3_0 FIXR(0.54119610014619698439) |
||

464 | #define COS3_1 FIXR(1.30656296487637652785) |
||

465 | |||

466 | #define COS4_0 FIXR(0.70710678118654752439) |
||

467 | |||

468 | ```
/* butterfly operator */
``` |
||

469 | ```
#define BF(a, b, c)\
``` |
||

470 | {\ |
||

471 | tmp0 = tab[a] + tab[b];\ |
||

472 | tmp1 = tab[a] - tab[b];\ |
||

473 | tab[a] = tmp0;\ |
||

474 | tab[b] = MULL(tmp1, c);\ |
||

475 | } |
||

476 | |||

477 | ```
#define BF1(a, b, c, d)\
``` |
||

478 | {\ |
||

479 | BF(a, b, COS4_0);\ |
||

480 | BF(c, d, -COS4_0);\ |
||

481 | tab[c] += tab[d];\ |
||

482 | } |
||

483 | |||

484 | ```
#define BF2(a, b, c, d)\
``` |
||

485 | {\ |
||

486 | BF(a, b, COS4_0);\ |
||

487 | BF(c, d, -COS4_0);\ |
||

488 | tab[c] += tab[d];\ |
||

489 | tab[a] += tab[c];\ |
||

490 | tab[c] += tab[b];\ |
||

491 | tab[b] += tab[d];\ |
||

492 | } |
||

493 | |||

494 | ```
#define ADD(a, b) tab[a] += tab[b]
``` |
||

495 | |||

496 | ```
/* DCT32 without 1/sqrt(2) coef zero scaling. */
``` |
||

497 | static void dct32(INT32 *out, INT32 *tab) |
||

498 | { |
||

499 | ```
int tmp0, tmp1;
``` |
||

500 | |||

501 | ```
/* pass 1 */
``` |
||

502 | BF(0, 31, COS0_0); |
||

503 | BF(1, 30, COS0_1); |
||

504 | BF(2, 29, COS0_2); |
||

505 | BF(3, 28, COS0_3); |
||

506 | BF(4, 27, COS0_4); |
||

507 | BF(5, 26, COS0_5); |
||

508 | BF(6, 25, COS0_6); |
||

509 | BF(7, 24, COS0_7); |
||

510 | BF(8, 23, COS0_8); |
||

511 | BF(9, 22, COS0_9); |
||

512 | BF(10, 21, COS0_10); |
||

513 | BF(11, 20, COS0_11); |
||

514 | BF(12, 19, COS0_12); |
||

515 | BF(13, 18, COS0_13); |
||

516 | BF(14, 17, COS0_14); |
||

517 | BF(15, 16, COS0_15); |
||

518 | |||

519 | ```
/* pass 2 */
``` |
||

520 | BF(0, 15, COS1_0); |
||

521 | BF(1, 14, COS1_1); |
||

522 | BF(2, 13, COS1_2); |
||

523 | BF(3, 12, COS1_3); |
||

524 | BF(4, 11, COS1_4); |
||

525 | BF(5, 10, COS1_5); |
||

526 | BF(6, 9, COS1_6); |
||

527 | BF(7, 8, COS1_7); |
||

528 | |||

529 | BF(16, 31, -COS1_0); |
||

530 | BF(17, 30, -COS1_1); |
||

531 | BF(18, 29, -COS1_2); |
||

532 | BF(19, 28, -COS1_3); |
||

533 | BF(20, 27, -COS1_4); |
||

534 | BF(21, 26, -COS1_5); |
||

535 | BF(22, 25, -COS1_6); |
||

536 | BF(23, 24, -COS1_7); |
||

537 | |||

538 | ```
/* pass 3 */
``` |
||

539 | BF(0, 7, COS2_0); |
||

540 | BF(1, 6, COS2_1); |
||

541 | BF(2, 5, COS2_2); |
||

542 | BF(3, 4, COS2_3); |
||

543 | |||

544 | BF(8, 15, -COS2_0); |
||

545 | BF(9, 14, -COS2_1); |
||

546 | BF(10, 13, -COS2_2); |
||

547 | BF(11, 12, -COS2_3); |
||

548 | |||

549 | BF(16, 23, COS2_0); |
||

550 | BF(17, 22, COS2_1); |
||

551 | BF(18, 21, COS2_2); |
||

552 | BF(19, 20, COS2_3); |
||

553 | |||

554 | BF(24, 31, -COS2_0); |
||

555 | BF(25, 30, -COS2_1); |
||

556 | BF(26, 29, -COS2_2); |
||

557 | BF(27, 28, -COS2_3); |
||

558 | |||

559 | ```
/* pass 4 */
``` |
||

560 | BF(0, 3, COS3_0); |
||

561 | BF(1, 2, COS3_1); |
||

562 | |||

563 | BF(4, 7, -COS3_0); |
||

564 | BF(5, 6, -COS3_1); |
||

565 | |||

566 | BF(8, 11, COS3_0); |
||

567 | BF(9, 10, COS3_1); |
||

568 | |||

569 | BF(12, 15, -COS3_0); |
||

570 | BF(13, 14, -COS3_1); |
||

571 | |||

572 | BF(16, 19, COS3_0); |
||

573 | BF(17, 18, COS3_1); |
||

574 | |||

575 | BF(20, 23, -COS3_0); |
||

576 | BF(21, 22, -COS3_1); |
||

577 | |||

578 | BF(24, 27, COS3_0); |
||

579 | BF(25, 26, COS3_1); |
||

580 | |||

581 | BF(28, 31, -COS3_0); |
||

582 | BF(29, 30, -COS3_1); |
||

583 | |||

584 | ```
/* pass 5 */
``` |
||

585 | BF1(0, 1, 2, 3); |
||

586 | BF2(4, 5, 6, 7); |
||

587 | BF1(8, 9, 10, 11); |
||

588 | BF2(12, 13, 14, 15); |
||

589 | BF1(16, 17, 18, 19); |
||

590 | BF2(20, 21, 22, 23); |
||

591 | BF1(24, 25, 26, 27); |
||

592 | BF2(28, 29, 30, 31); |
||

593 | |||

594 | ```
/* pass 6 */
``` |
||

595 | |||

596 | ADD( 8, 12); |
||

597 | ADD(12, 10); |
||

598 | ADD(10, 14); |
||

599 | ADD(14, 9); |
||

600 | ADD( 9, 13); |
||

601 | ADD(13, 11); |
||

602 | ADD(11, 15); |
||

603 | |||

604 | out[ 0] = tab[0]; |
||

605 | out[16] = tab[1]; |
||

606 | out[ 8] = tab[2]; |
||

607 | out[24] = tab[3]; |
||

608 | out[ 4] = tab[4]; |
||

609 | out[20] = tab[5]; |
||

610 | out[12] = tab[6]; |
||

611 | out[28] = tab[7]; |
||

612 | out[ 2] = tab[8]; |
||

613 | out[18] = tab[9]; |
||

614 | out[10] = tab[10]; |
||

615 | out[26] = tab[11]; |
||

616 | out[ 6] = tab[12]; |
||

617 | out[22] = tab[13]; |
||

618 | out[14] = tab[14]; |
||

619 | out[30] = tab[15]; |
||

620 | |||

621 | ADD(24, 28); |
||

622 | ADD(28, 26); |
||

623 | ADD(26, 30); |
||

624 | ADD(30, 25); |
||

625 | ADD(25, 29); |
||

626 | ADD(29, 27); |
||

627 | ADD(27, 31); |
||

628 | |||

629 | out[ 1] = tab[16] + tab[24]; |
||

630 | out[17] = tab[17] + tab[25]; |
||

631 | out[ 9] = tab[18] + tab[26]; |
||

632 | out[25] = tab[19] + tab[27]; |
||

633 | out[ 5] = tab[20] + tab[28]; |
||

634 | out[21] = tab[21] + tab[29]; |
||

635 | out[13] = tab[22] + tab[30]; |
||

636 | out[29] = tab[23] + tab[31]; |
||

637 | out[ 3] = tab[24] + tab[20]; |
||

638 | out[19] = tab[25] + tab[21]; |
||

639 | out[11] = tab[26] + tab[22]; |
||

640 | out[27] = tab[27] + tab[23]; |
||

641 | out[ 7] = tab[28] + tab[18]; |
||

642 | out[23] = tab[29] + tab[19]; |
||

643 | out[15] = tab[30] + tab[17]; |
||

644 | out[31] = tab[31]; |
||

645 | } |
||

646 | |||

647 | #define OUT_SHIFT (WFRAC_BITS + FRAC_BITS - 15) |
||

648 | |||

649 | #if FRAC_BITS <= 15 |
||

650 | |||

651 | ```
#define OUT_SAMPLE(sum)\
``` |
||

652 | {\ |
||

653 | ```
int sum1;\
``` |
||

654 | sum1 = (sum + (1 << (OUT_SHIFT - 1))) >> OUT_SHIFT;\ |
||

655 | if (sum1 < -32768)\ |
||

656 | ```
sum1 = -32768;\
``` |
||

657 | else if (sum1 > 32767)\ |
||

658 | ```
sum1 = 32767;\
``` |
||

659 | *samples = sum1;\ |
||

660 | samples += incr;\ |
||

661 | } |
||

662 | |||

663 | ```
#define SUM8(off, op) \
``` |
||

664 | { \ |
||

665 | sum op w[0 * 64 + off] * p[0 * 64];\ |
||

666 | sum op w[1 * 64 + off] * p[1 * 64];\ |
||

667 | sum op w[2 * 64 + off] * p[2 * 64];\ |
||

668 | sum op w[3 * 64 + off] * p[3 * 64];\ |
||

669 | sum op w[4 * 64 + off] * p[4 * 64];\ |
||

670 | sum op w[5 * 64 + off] * p[5 * 64];\ |
||

671 | sum op w[6 * 64 + off] * p[6 * 64];\ |
||

672 | sum op w[7 * 64 + off] * p[7 * 64];\ |
||

673 | } |
||

674 | |||

675 | ```
#else
``` |
||

676 | |||

677 | ```
#define OUT_SAMPLE(sum)\
``` |
||

678 | {\ |
||

679 | ```
int sum1;\
``` |
||

680 | sum1 = (int)((sum + (INT64_C(1) << (OUT_SHIFT - 1))) >> OUT_SHIFT);\ |
||

681 | if (sum1 < -32768)\ |
||

682 | ```
sum1 = -32768;\
``` |
||

683 | else if (sum1 > 32767)\ |
||

684 | ```
sum1 = 32767;\
``` |
||

685 | *samples = sum1;\ |
||

686 | samples += incr;\ |
||

687 | } |
||

688 | |||

689 | ```
#define SUM8(off, op) \
``` |
||

690 | { \ |
||

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

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

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

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

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

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

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

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

699 | } |
||

700 | |||

701 | ```
#endif
``` |
||

702 | |||

703 | ```
/* 32 sub band synthesis filter. Input: 32 sub band samples, Output:
``` |
||

704 | ```
32 samples. */
``` |
||

705 | ```
/* XXX: optimize by avoiding ring buffer usage */
``` |
||

706 | static void synth_filter(MPADecodeContext *s1, |
||

707 | int ch, INT16 *samples, int incr, |
||

708 | INT32 sb_samples[SBLIMIT]) |
||

709 | { |
||

710 | ```
INT32 tmp[32];
``` |
||

711 | ```
register MPA_INT *synth_buf, *p;
``` |
||

712 | ```
register MPA_INT *w;
``` |
||

713 | ```
int j, offset, v;
``` |
||

714 | #if FRAC_BITS <= 15 |
||

715 | ```
int sum;
``` |
||

716 | ```
#else
``` |
||

717 | INT64 sum; |
||

718 | ```
#endif
``` |
||

719 | |||

720 | dct32(tmp, sb_samples); |
||

721 | |||

722 | offset = s1->synth_buf_offset[ch]; |
||

723 | synth_buf = s1->synth_buf[ch] + offset; |
||

724 | |||

725 | for(j=0;j<32;j++) { |
||

726 | v = tmp[j]; |
||

727 | #if FRAC_BITS <= 15 |
||

728 | if (v > 32767) |
||

729 | ```
v = 32767;
``` |
||

730 | else if (v < -32768) |
||

731 | ```
v = -32768;
``` |
||

732 | ```
#endif
``` |
||

733 | synth_buf[j] = v; |
||

734 | } |
||

735 | ```
/* copy to avoid wrap */
``` |
||

736 | memcpy(synth_buf + 512, synth_buf, 32 * sizeof(MPA_INT)); |
||

737 | |||

738 | w = window; |
||

739 | for(j=0;j<16;j++) { |
||

740 | ```
sum = 0;
``` |
||

741 | p = synth_buf + 16 + j; /* 0-15 */ |
||

742 | ```
SUM8(0, +=);
``` |
||

743 | p = synth_buf + 48 - j; /* 32-47 */ |
||

744 | ```
SUM8(32, -=);
``` |
||

745 | OUT_SAMPLE(sum); |
||

746 | w++; |
||

747 | } |
||

748 | |||

749 | p = synth_buf + 32; /* 48 */ |
||

750 | ```
sum = 0;
``` |
||

751 | ```
SUM8(32, -=);
``` |
||

752 | OUT_SAMPLE(sum); |
||

753 | w++; |
||

754 | |||

755 | for(j=17;j<32;j++) { |
||

756 | ```
sum = 0;
``` |
||

757 | p = synth_buf + 48 - j; /* 17-31 */ |
||

758 | ```
SUM8(0, -=);
``` |
||

759 | p = synth_buf + 16 + j; /* 49-63 */ |
||

760 | ```
SUM8(32, -=);
``` |
||

761 | OUT_SAMPLE(sum); |
||

762 | w++; |
||

763 | } |
||

764 | offset = (offset - 32) & 511; |
||

765 | s1->synth_buf_offset[ch] = offset; |
||

766 | } |
||

767 | |||

768 | ```
/* cos(pi*i/24) */
``` |
||

769 | #define C1 FIXR(0.99144486137381041114) |
||

770 | #define C3 FIXR(0.92387953251128675612) |
||

771 | #define C5 FIXR(0.79335334029123516458) |
||

772 | #define C7 FIXR(0.60876142900872063941) |
||

773 | #define C9 FIXR(0.38268343236508977173) |
||

774 | #define C11 FIXR(0.13052619222005159154) |
||

775 | |||

776 | ```
/* 12 points IMDCT. We compute it "by hand" by factorizing obvious
``` |
||

777 | ```
cases. */
``` |
||

778 | static void imdct12(int *out, int *in) |
||

779 | { |
||

780 | ```
int tmp;
``` |
||

781 | INT64 in1_3, in1_9, in4_3, in4_9; |
||

782 | |||

783 | ```
in1_3 = MUL64(in[1], C3);
``` |
||

784 | ```
in1_9 = MUL64(in[1], C9);
``` |
||

785 | ```
in4_3 = MUL64(in[4], C3);
``` |
||

786 | ```
in4_9 = MUL64(in[4], C9);
``` |
||

787 | |||

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

789 | MUL64(in[3], C1) - in4_9 - MUL64(in[5], C5)); |
||

790 | ```
out[0] = tmp;
``` |
||

791 | ```
out[5] = -tmp;
``` |
||

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

793 | MUL64(in[2] + in[5], C3) - in4_9); |
||

794 | ```
out[1] = tmp;
``` |
||

795 | ```
out[4] = -tmp;
``` |
||

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

797 | MUL64(in[3], C5) + in4_3 - MUL64(in[5], C1)); |
||

798 | ```
out[2] = tmp;
``` |
||

799 | ```
out[3] = -tmp;
``` |
||

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

801 | MUL64(in[3], C11) - in4_3 - MUL64(in[5], C7)); |
||

802 | ```
out[6] = tmp;
``` |
||

803 | ```
out[11] = tmp;
``` |
||

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

805 | MUL64(in[2] + in[5], C9) + in4_3); |
||

806 | ```
out[7] = tmp;
``` |
||

807 | ```
out[10] = tmp;
``` |
||

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

809 | MUL64(in[3], C7) - in4_9 - MUL64(in[5], C11)); |
||

810 | ```
out[8] = tmp;
``` |
||

811 | ```
out[9] = tmp;
``` |
||

812 | } |
||

813 | |||

814 | ```
#undef C1
``` |
||

815 | ```
#undef C3
``` |
||

816 | ```
#undef C5
``` |
||

817 | ```
#undef C7
``` |
||

818 | ```
#undef C9
``` |
||

819 | ```
#undef C11
``` |
||

820 | |||

821 | ```
/* cos(pi*i/18) */
``` |
||

822 | #define C1 FIXR(0.98480775301220805936) |
||

823 | #define C2 FIXR(0.93969262078590838405) |
||

824 | #define C3 FIXR(0.86602540378443864676) |
||

825 | #define C4 FIXR(0.76604444311897803520) |
||

826 | #define C5 FIXR(0.64278760968653932632) |
||

827 | #define C6 FIXR(0.5) |
||

828 | #define C7 FIXR(0.34202014332566873304) |
||

829 | #define C8 FIXR(0.17364817766693034885) |
||

830 | |||

831 | ```
/* 0.5 / cos(pi*(2*i+1)/36) */
``` |
||

832 | static const int icos36[9] = { |
||

833 | FIXR(0.50190991877167369479), |
||

834 | FIXR(0.51763809020504152469), |
||

835 | FIXR(0.55168895948124587824), |
||

836 | FIXR(0.61038729438072803416), |
||

837 | FIXR(0.70710678118654752439), |
||

838 | FIXR(0.87172339781054900991), |
||

839 | FIXR(1.18310079157624925896), |
||

840 | FIXR(1.93185165257813657349), |
||

841 | FIXR(5.73685662283492756461), |
||

842 | }; |
||

843 | |||

844 | static const int icos72[18] = { |
||

845 | ```
/* 0.5 / cos(pi*(2*i+19)/72) */
``` |
||

846 | FIXR(0.74009361646113053152), |
||

847 | FIXR(0.82133981585229078570), |
||

848 | FIXR(0.93057949835178895673), |
||

849 | FIXR(1.08284028510010010928), |
||

850 | FIXR(1.30656296487637652785), |
||

851 | FIXR(1.66275476171152078719), |
||

852 | FIXR(2.31011315767264929558), |
||

853 | FIXR(3.83064878777019433457), |
||

854 | FIXR(11.46279281302667383546), |
||

855 | |||

856 | ```
/* 0.5 / cos(pi*(2*(i + 18) +19)/72) */
``` |
||

857 | FIXR(-0.67817085245462840086), |
||

858 | FIXR(-0.63023620700513223342), |
||

859 | FIXR(-0.59284452371708034528), |
||

860 | FIXR(-0.56369097343317117734), |
||

861 | FIXR(-0.54119610014619698439), |
||

862 | FIXR(-0.52426456257040533932), |
||

863 | FIXR(-0.51213975715725461845), |
||

864 | FIXR(-0.50431448029007636036), |
||

865 | FIXR(-0.50047634258165998492), |
||

866 | }; |
||

867 | |||

868 | ```
/* using Lee like decomposition followed by hand coded 9 points DCT */
``` |
||

869 | static void imdct36(int *out, int *in) |
||

870 | { |
||

871 | ```
int i, j, t0, t1, t2, t3, s0, s1, s2, s3;
``` |
||

872 | int tmp[18], *tmp1, *in1; |
||

873 | INT64 in3_3, in6_6; |
||

874 | |||

875 | for(i=17;i>=1;i--) |
||

876 | ```
in[i] += in[i-1];
``` |
||

877 | for(i=17;i>=3;i-=2) |
||

878 | ```
in[i] += in[i-2];
``` |
||

879 | |||

880 | for(j=0;j<2;j++) { |
||

881 | tmp1 = tmp + j; |
||

882 | in1 = in + j; |
||

883 | |||

884 | in3_3 = MUL64(in1[2*3], C3); |
||

885 | in6_6 = MUL64(in1[2*6], C6); |
||

886 | |||

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

888 | MUL64(in1[2*5], C5) + MUL64(in1[2*7], C7)); |
||

889 | tmp1[2] = in1[2*0] + FRAC_RND(MUL64(in1[2*2], C2) + |
||

890 | MUL64(in1[2*4], C4) + in6_6 + |
||

891 | MUL64(in1[2*8], C8)); |
||

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

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

894 | in1[2*6] + in1[2*0]; |
||

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

896 | MUL64(in1[2*5], C7) + MUL64(in1[2*7], C1)); |
||

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

898 | MUL64(in1[2*4], C2) + in6_6 + |
||

899 | MUL64(in1[2*8], C4)); |
||

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

901 | MUL64(in1[2*5], C1) - |
||

902 | MUL64(in1[2*7], C5)); |
||

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

904 | MUL64(in1[2*4], C8) + in6_6 - |
||

905 | MUL64(in1[2*8], C2)); |
||

906 | tmp1[16] = in1[2*0] - in1[2*2] + in1[2*4] - in1[2*6] + in1[2*8]; |
||

907 | } |
||

908 | |||

909 | ```
i = 0;
``` |
||

910 | for(j=0;j<4;j++) { |
||

911 | t0 = tmp[i]; |
||

912 | ```
t1 = tmp[i + 2];
``` |
||

913 | s0 = t1 + t0; |
||

914 | s2 = t1 - t0; |
||

915 | |||

916 | ```
t2 = tmp[i + 1];
``` |
||

917 | ```
t3 = tmp[i + 3];
``` |
||

918 | s1 = MULL(t3 + t2, icos36[j]); |
||

919 | ```
s3 = MULL(t3 - t2, icos36[8 - j]);
``` |
||

920 | |||

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

922 | ```
t1 = MULL(s0 - s1, icos72[8 - j]);
``` |
||

923 | out[18 + 9 + j] = t0; |
||

924 | out[18 + 8 - j] = t0; |
||

925 | ```
out[9 + j] = -t1;
``` |
||

926 | ```
out[8 - j] = t1;
``` |
||

927 | |||

928 | ```
t0 = MULL(s2 + s3, icos72[9+j]);
``` |
||

929 | t1 = MULL(s2 - s3, icos72[j]); |
||

930 | out[18 + 9 + (8 - j)] = t0; |
||

931 | ```
out[18 + j] = t0;
``` |
||

932 | out[9 + (8 - j)] = -t1; |
||

933 | out[j] = t1; |
||

934 | ```
i += 4;
``` |
||

935 | } |
||

936 | |||

937 | ```
s0 = tmp[16];
``` |
||

938 | s1 = MULL(tmp[17], icos36[4]); |
||

939 | t0 = MULL(s0 + s1, icos72[9 + 4]); |
||

940 | ```
t1 = MULL(s0 - s1, icos72[4]);
``` |
||

941 | out[18 + 9 + 4] = t0; |
||

942 | out[18 + 8 - 4] = t0; |
||

943 | out[9 + 4] = -t1; |
||

944 | out[8 - 4] = t1; |
||

945 | } |
||

946 | |||

947 | de6d9b64 | Fabrice Bellard | ```
/* fast header check for resync */
``` |

948 | static int check_header(UINT32 header) |
||

949 | { |
||

950 | ```
/* header */
``` |
||

951 | if ((header & 0xffe00000) != 0xffe00000) |
||

952 | return -1; |
||

953 | ```
/* layer check */
``` |
||

954 | if (((header >> 17) & 3) == 0) |
||

955 | return -1; |
||

956 | 239c2f4c | Fabrice Bellard | ```
/* bit rate */
``` |

957 | if (((header >> 12) & 0xf) == 0xf) |
||

958 | de6d9b64 | Fabrice Bellard | return -1; |

959 | ```
/* frequency */
``` |
||

960 | if (((header >> 10) & 3) == 3) |
||

961 | return -1; |
||

962 | return 0; |
||

963 | } |
||

964 | |||

965 | 239c2f4c | Fabrice Bellard | ```
/* header + layer + bitrate + freq + lsf/mpeg25 */
``` |

966 | ```
#define SAME_HEADER_MASK \
``` |
||

967 | (0xffe00000 | (3 << 17) | (0xf << 12) | (3 << 10) | (3 << 19)) |
||

968 | |||

969 | de6d9b64 | Fabrice Bellard | ```
/* header decoding. MUST check the header before because no
``` |

970 | 239c2f4c | Fabrice Bellard | ```
consistency check is done there. Return 1 if free format found and
``` |

971 | ```
that the frame size must be computed externally */
``` |
||

972 | static int decode_header(MPADecodeContext *s, UINT32 header) |
||

973 | de6d9b64 | Fabrice Bellard | { |

974 | 239c2f4c | Fabrice Bellard | ```
int sample_rate, frame_size, mpeg25, padding;
``` |

975 | ```
int sample_rate_index, bitrate_index;
``` |
||

976 | de6d9b64 | Fabrice Bellard | if (header & (1<<20)) { |

977 | 239c2f4c | Fabrice Bellard | s->lsf = (header & (1<<19)) ? 0 : 1; |

978 | ```
mpeg25 = 0;
``` |
||

979 | de6d9b64 | Fabrice Bellard | ```
} else {
``` |

980 | 239c2f4c | Fabrice Bellard | ```
s->lsf = 1;
``` |

981 | ```
mpeg25 = 1;
``` |
||

982 | de6d9b64 | Fabrice Bellard | } |

983 | |||

984 | s->layer = 4 - ((header >> 17) & 3); |
||

985 | ```
/* extract frequency */
``` |
||

986 | 239c2f4c | Fabrice Bellard | sample_rate_index = (header >> 10) & 3; |

987 | sample_rate = mpa_freq_tab[sample_rate_index] >> (s->lsf + mpeg25); |
||

988 | de5123dc | Zdenek Kabelac | if (sample_rate == 0) |

989 | return 1; |
||

990 | 239c2f4c | Fabrice Bellard | ```
sample_rate_index += 3 * (s->lsf + mpeg25);
``` |

991 | s->sample_rate_index = sample_rate_index; |
||

992 | s->error_protection = ((header >> 16) & 1) ^ 1; |
||

993 | de6d9b64 | Fabrice Bellard | |

994 | 239c2f4c | Fabrice Bellard | bitrate_index = (header >> 12) & 0xf; |

995 | padding = (header >> 9) & 1; |
||

996 | ```
//extension = (header >> 8) & 1;
``` |
||

997 | s->mode = (header >> 6) & 3; |
||

998 | s->mode_ext = (header >> 4) & 3; |
||

999 | ```
//copyright = (header >> 3) & 1;
``` |
||

1000 | ```
//original = (header >> 2) & 1;
``` |
||

1001 | ```
//emphasis = header & 3;
``` |
||

1002 | de6d9b64 | Fabrice Bellard | |

1003 | 239c2f4c | Fabrice Bellard | ```
if (s->mode == MPA_MONO)
``` |

1004 | ```
s->nb_channels = 1;
``` |
||

1005 | ```
else
``` |
||

1006 | ```
s->nb_channels = 2;
``` |
||

1007 | de6d9b64 | Fabrice Bellard | |

1008 | 239c2f4c | Fabrice Bellard | if (bitrate_index != 0) { |

1009 | ```
frame_size = mpa_bitrate_tab[s->lsf][s->layer - 1][bitrate_index];
``` |
||

1010 | ```
s->bit_rate = frame_size * 1000;
``` |
||

1011 | ```
switch(s->layer) {
``` |
||

1012 | case 1: |
||

1013 | ```
frame_size = (frame_size * 12000) / sample_rate;
``` |
||

1014 | ```
frame_size = (frame_size + padding) * 4;
``` |
||

1015 | ```
break;
``` |
||

1016 | case 2: |
||

1017 | ```
frame_size = (frame_size * 144000) / sample_rate;
``` |
||

1018 | frame_size += padding; |
||

1019 | ```
break;
``` |
||

1020 | ```
default:
``` |
||

1021 | case 3: |
||

1022 | ```
frame_size = (frame_size * 144000) / (sample_rate << s->lsf);
``` |
||

1023 | frame_size += padding; |
||

1024 | ```
break;
``` |
||

1025 | } |
||

1026 | s->frame_size = frame_size; |
||

1027 | ```
} else {
``` |
||

1028 | ```
/* if no frame size computed, signal it */
``` |
||

1029 | ```
if (!s->free_format_frame_size)
``` |
||

1030 | return 1; |
||

1031 | ```
/* free format: compute bitrate and real frame size from the
``` |
||

1032 | ```
frame size we extracted by reading the bitstream */
``` |
||

1033 | s->frame_size = s->free_format_frame_size; |
||

1034 | ```
switch(s->layer) {
``` |
||

1035 | case 1: |
||

1036 | ```
s->frame_size += padding * 4;
``` |
||

1037 | ```
s->bit_rate = (s->frame_size * sample_rate) / 48000;
``` |
||

1038 | ```
break;
``` |
||

1039 | case 2: |
||

1040 | s->frame_size += padding; |
||

1041 | ```
s->bit_rate = (s->frame_size * sample_rate) / 144000;
``` |
||

1042 | ```
break;
``` |
||

1043 | ```
default:
``` |
||

1044 | case 3: |
||

1045 | s->frame_size += padding; |
||

1046 | ```
s->bit_rate = (s->frame_size * (sample_rate << s->lsf)) / 144000;
``` |
||

1047 | ```
break;
``` |
||

1048 | } |
||

1049 | de6d9b64 | Fabrice Bellard | } |

1050 | s->sample_rate = sample_rate; |
||

1051 | 239c2f4c | Fabrice Bellard | |

1052 | ```
#ifdef DEBUG
``` |
||

1053 | ```
printf("layer%d, %d Hz, %d kbits/s, ",
``` |
||

1054 | s->layer, s->sample_rate, s->bit_rate); |
||

1055 | if (s->nb_channels == 2) { |
||

1056 | if (s->layer == 3) { |
||

1057 | ```
if (s->mode_ext & MODE_EXT_MS_STEREO)
``` |
||

1058 | ```
printf("ms-");
``` |
||

1059 | ```
if (s->mode_ext & MODE_EXT_I_STEREO)
``` |
||

1060 | ```
printf("i-");
``` |
||

1061 | } |
||

1062 | ```
printf("stereo");
``` |
||

1063 | ```
} else {
``` |
||

1064 | ```
printf("mono");
``` |
||

1065 | } |
||

1066 | ```
printf("\n");
``` |
||

1067 | de6d9b64 | Fabrice Bellard | ```
#endif
``` |

1068 | 239c2f4c | Fabrice Bellard | return 0; |

1069 | de6d9b64 | Fabrice Bellard | } |

1070 | |||

1071 | 239c2f4c | Fabrice Bellard | ```
/* return the number of decoded frames */
``` |

1072 | static int mp_decode_layer1(MPADecodeContext *s) |
||

1073 | de6d9b64 | Fabrice Bellard | { |

1074 | 239c2f4c | Fabrice Bellard | ```
int bound, i, v, n, ch, j, mant;
``` |

1075 | UINT8 allocation[MPA_MAX_CHANNELS][SBLIMIT]; |
||

1076 | UINT8 scale_factors[MPA_MAX_CHANNELS][SBLIMIT]; |
||

1077 | |||

1078 | ```
if (s->mode == MPA_JSTEREO)
``` |
||

1079 | bound = (s->mode_ext + 1) * 4; |
||

1080 | ```
else
``` |
||

1081 | bound = SBLIMIT; |
||

1082 | |||

1083 | ```
/* allocation bits */
``` |
||

1084 | for(i=0;i<bound;i++) { |
||

1085 | for(ch=0;ch<s->nb_channels;ch++) { |
||

1086 | ```
allocation[ch][i] = get_bits(&s->gb, 4);
``` |
||

1087 | } |
||

1088 | } |
||

1089 | ```
for(i=bound;i<SBLIMIT;i++) {
``` |
||

1090 | allocation[0][i] = get_bits(&s->gb, 4); |
||

1091 | } |
||

1092 | |||

1093 | ```
/* scale factors */
``` |
||

1094 | for(i=0;i<bound;i++) { |
||

1095 | for(ch=0;ch<s->nb_channels;ch++) { |
||

1096 | ```
if (allocation[ch][i])
``` |
||

1097 | ```
scale_factors[ch][i] = get_bits(&s->gb, 6);
``` |
||

1098 | } |
||

1099 | } |
||

1100 | ```
for(i=bound;i<SBLIMIT;i++) {
``` |
||

1101 | if (allocation[0][i]) { |
||

1102 | scale_factors[0][i] = get_bits(&s->gb, 6); |
||

1103 | scale_factors[1][i] = get_bits(&s->gb, 6); |
||

1104 | } |
||

1105 | } |
||

1106 | de6d9b64 | Fabrice Bellard | |

1107 | 239c2f4c | Fabrice Bellard | ```
/* compute samples */
``` |

1108 | for(j=0;j<12;j++) { |
||

1109 | for(i=0;i<bound;i++) { |
||

1110 | for(ch=0;ch<s->nb_channels;ch++) { |
||

1111 | n = allocation[ch][i]; |
||

1112 | ```
if (n) {
``` |
||

1113 | ```
mant = get_bits(&s->gb, n + 1);
``` |
||

1114 | v = l1_unscale(n, mant, scale_factors[ch][i]); |
||

1115 | ```
} else {
``` |
||

1116 | ```
v = 0;
``` |
||

1117 | } |
||

1118 | s->sb_samples[ch][j][i] = v; |
||

1119 | } |
||

1120 | } |
||

1121 | ```
for(i=bound;i<SBLIMIT;i++) {
``` |
||

1122 | ```
n = allocation[0][i];
``` |
||

1123 | ```
if (n) {
``` |
||

1124 | ```
mant = get_bits(&s->gb, n + 1);
``` |
||

1125 | ```
v = l1_unscale(n, mant, scale_factors[0][i]);
``` |
||

1126 | ```
s->sb_samples[0][j][i] = v;
``` |
||

1127 | ```
v = l1_unscale(n, mant, scale_factors[1][i]);
``` |
||

1128 | ```
s->sb_samples[1][j][i] = v;
``` |
||

1129 | ```
} else {
``` |
||

1130 | s->sb_samples[0][j][i] = 0; |
||

1131 | s->sb_samples[1][j][i] = 0; |
||

1132 | } |
||

1133 | } |
||

1134 | } |
||

1135 | return 12; |
||

1136 | } |
||

1137 | |||

1138 | ```
/* bitrate is in kb/s */
``` |
||

1139 | int l2_select_table(int bitrate, int nb_channels, int freq, int lsf) |
||

1140 | { |
||

1141 | ```
int ch_bitrate, table;
``` |
||

1142 | de6d9b64 | Fabrice Bellard | |

1143 | 239c2f4c | Fabrice Bellard | ch_bitrate = bitrate / nb_channels; |

1144 | ```
if (!lsf) {
``` |
||

1145 | if ((freq == 48000 && ch_bitrate >= 56) || |
||

1146 | (ch_bitrate >= 56 && ch_bitrate <= 80)) |
||

1147 | ```
table = 0;
``` |
||

1148 | else if (freq != 48000 && ch_bitrate >= 96) |
||

1149 | ```
table = 1;
``` |
||

1150 | else if (freq != 32000 && ch_bitrate <= 48) |
||

1151 | ```
table = 2;
``` |
||

1152 | ```
else
``` |
||

1153 | ```
table = 3;
``` |
||

1154 | ```
} else {
``` |
||

1155 | ```
table = 4;
``` |
||

1156 | } |
||

1157 | ```
return table;
``` |
||

1158 | } |
||

1159 | de6d9b64 | Fabrice Bellard | |

1160 | 239c2f4c | Fabrice Bellard | static int mp_decode_layer2(MPADecodeContext *s) |

1161 | { |
||

1162 | int sblimit; /* number of used subbands */ |
||

1163 | const unsigned char *alloc_table; |
||

1164 | ```
int table, bit_alloc_bits, i, j, ch, bound, v;
``` |
||

1165 | unsigned char bit_alloc[MPA_MAX_CHANNELS][SBLIMIT]; |
||

1166 | unsigned char scale_code[MPA_MAX_CHANNELS][SBLIMIT]; |
||

1167 | unsigned char scale_factors[MPA_MAX_CHANNELS][SBLIMIT][3], *sf; |
||

1168 | ```
int scale, qindex, bits, steps, k, l, m, b;
``` |
||

1169 | de6d9b64 | Fabrice Bellard | |

1170 | 239c2f4c | Fabrice Bellard | ```
/* select decoding table */
``` |

1171 | ```
table = l2_select_table(s->bit_rate / 1000, s->nb_channels,
``` |
||

1172 | s->sample_rate, s->lsf); |
||

1173 | sblimit = sblimit_table[table]; |
||

1174 | alloc_table = alloc_tables[table]; |
||

1175 | |||

1176 | ```
if (s->mode == MPA_JSTEREO)
``` |
||

1177 | bound = (s->mode_ext + 1) * 4; |
||

1178 | ```
else
``` |
||

1179 | bound = sblimit; |
||

1180 | |||

1181 | ```
dprintf("bound=%d sblimit=%d\n", bound, sblimit);
``` |
||

1182 | ```
/* parse bit allocation */
``` |
||

1183 | ```
j = 0;
``` |
||

1184 | for(i=0;i<bound;i++) { |
||

1185 | bit_alloc_bits = alloc_table[j]; |
||

1186 | for(ch=0;ch<s->nb_channels;ch++) { |
||

1187 | bit_alloc[ch][i] = get_bits(&s->gb, bit_alloc_bits); |
||

1188 | } |
||

1189 | ```
j += 1 << bit_alloc_bits;
``` |
||

1190 | } |
||

1191 | ```
for(i=bound;i<sblimit;i++) {
``` |
||

1192 | bit_alloc_bits = alloc_table[j]; |
||

1193 | v = get_bits(&s->gb, bit_alloc_bits); |
||

1194 | ```
bit_alloc[0][i] = v;
``` |
||

1195 | ```
bit_alloc[1][i] = v;
``` |
||

1196 | ```
j += 1 << bit_alloc_bits;
``` |
||

1197 | de6d9b64 | Fabrice Bellard | } |

1198 | 239c2f4c | Fabrice Bellard | |

1199 | ```
#ifdef DEBUG
``` |
||

1200 | { |
||

1201 | for(ch=0;ch<s->nb_channels;ch++) { |
||

1202 | for(i=0;i<sblimit;i++) |
||

1203 | ```
printf(" %d", bit_alloc[ch][i]);
``` |
||

1204 | ```
printf("\n");
``` |
||

1205 | } |
||

1206 | } |
||

1207 | ```
#endif
``` |
||

1208 | |||

1209 | ```
/* scale codes */
``` |
||

1210 | for(i=0;i<sblimit;i++) { |
||

1211 | for(ch=0;ch<s->nb_channels;ch++) { |
||

1212 | ```
if (bit_alloc[ch][i])
``` |
||

1213 | ```
scale_code[ch][i] = get_bits(&s->gb, 2);
``` |
||

1214 | } |
||

1215 | } |
||

1216 | |||

1217 | ```
/* scale factors */
``` |
||

1218 | for(i=0;i<sblimit;i++) { |
||

1219 | for(ch=0;ch<s->nb_channels;ch++) { |
||

1220 | ```
if (bit_alloc[ch][i]) {
``` |
||

1221 | sf = scale_factors[ch][i]; |
||

1222 | ```
switch(scale_code[ch][i]) {
``` |
||

1223 | ```
default:
``` |
||

1224 | case 0: |
||

1225 | sf[0] = get_bits(&s->gb, 6); |
||

1226 | sf[1] = get_bits(&s->gb, 6); |
||

1227 | sf[2] = get_bits(&s->gb, 6); |
||

1228 | ```
break;
``` |
||

1229 | case 2: |
||

1230 | sf[0] = get_bits(&s->gb, 6); |
||

1231 | sf[1] = sf[0]; |
||

1232 | sf[2] = sf[0]; |
||

1233 | ```
break;
``` |
||

1234 | case 1: |
||

1235 | sf[0] = get_bits(&s->gb, 6); |
||

1236 | sf[2] = get_bits(&s->gb, 6); |
||

1237 | sf[1] = sf[0]; |
||

1238 | ```
break;
``` |
||

1239 | case 3: |
||

1240 | sf[0] = get_bits(&s->gb, 6); |
||

1241 | sf[2] = get_bits(&s->gb, 6); |
||

1242 | sf[1] = sf[2]; |
||

1243 | ```
break;
``` |
||

1244 | } |
||

1245 | } |
||

1246 | } |
||

1247 | } |
||

1248 | |||

1249 | ```
#ifdef DEBUG
``` |
||

1250 | for(ch=0;ch<s->nb_channels;ch++) { |
||

1251 | for(i=0;i<sblimit;i++) { |
||

1252 | ```
if (bit_alloc[ch][i]) {
``` |
||

1253 | sf = scale_factors[ch][i]; |
||

1254 | printf(" %d %d %d", sf[0], sf[1], sf[2]); |
||

1255 | ```
} else {
``` |
||

1256 | ```
printf(" -");
``` |
||

1257 | } |
||

1258 | } |
||

1259 | ```
printf("\n");
``` |
||

1260 | } |
||

1261 | ```
#endif
``` |
||

1262 | |||

1263 | ```
/* samples */
``` |
||

1264 | for(k=0;k<3;k++) { |
||

1265 | for(l=0;l<12;l+=3) { |
||

1266 | ```
j = 0;
``` |
||

1267 | for(i=0;i<bound;i++) { |
||

1268 | bit_alloc_bits = alloc_table[j]; |
||

1269 | for(ch=0;ch<s->nb_channels;ch++) { |
||

1270 | b = bit_alloc[ch][i]; |
||

1271 | ```
if (b) {
``` |
||

1272 | scale = scale_factors[ch][i][k]; |
||

1273 | qindex = alloc_table[j+b]; |
||

1274 | bits = quant_bits[qindex]; |
||

1275 | if (bits < 0) { |
||

1276 | ```
/* 3 values at the same time */
``` |
||

1277 | v = get_bits(&s->gb, -bits); |
||

1278 | steps = quant_steps[qindex]; |
||

1279 | s->sb_samples[ch][k * 12 + l + 0][i] = |
||

1280 | l2_unscale_group(steps, v % steps, scale); |
||

1281 | v = v / steps; |
||

1282 | s->sb_samples[ch][k * 12 + l + 1][i] = |
||

1283 | l2_unscale_group(steps, v % steps, scale); |
||

1284 | v = v / steps; |
||

1285 | s->sb_samples[ch][k * 12 + l + 2][i] = |
||

1286 | l2_unscale_group(steps, v, scale); |
||

1287 | ```
} else {
``` |
||

1288 | for(m=0;m<3;m++) { |
||

1289 | v = get_bits(&s->gb, bits); |
||

1290 | ```
v = l1_unscale(bits - 1, v, scale);
``` |
||

1291 | ```
s->sb_samples[ch][k * 12 + l + m][i] = v;
``` |
||

1292 | } |
||

1293 | } |
||

1294 | ```
} else {
``` |
||

1295 | s->sb_samples[ch][k * 12 + l + 0][i] = 0; |
||

1296 | s->sb_samples[ch][k * 12 + l + 1][i] = 0; |
||

1297 | s->sb_samples[ch][k * 12 + l + 2][i] = 0; |
||

1298 | } |
||

1299 | } |
||

1300 | ```
/* next subband in alloc table */
``` |
||

1301 | ```
j += 1 << bit_alloc_bits;
``` |
||

1302 | } |
||

1303 | ```
/* XXX: find a way to avoid this duplication of code */
``` |
||

1304 | ```
for(i=bound;i<sblimit;i++) {
``` |
||

1305 | bit_alloc_bits = alloc_table[j]; |
||

1306 | ```
b = bit_alloc[0][i];
``` |
||

1307 | ```
if (b) {
``` |
||

1308 | ```
int mant, scale0, scale1;
``` |
||

1309 | ```
scale0 = scale_factors[0][i][k];
``` |
||

1310 | ```
scale1 = scale_factors[1][i][k];
``` |
||

1311 | qindex = alloc_table[j+b]; |
||

1312 | bits = quant_bits[qindex]; |
||

1313 | if (bits < 0) { |
||

1314 | ```
/* 3 values at the same time */
``` |
||

1315 | v = get_bits(&s->gb, -bits); |
||

1316 | steps = quant_steps[qindex]; |
||

1317 | mant = v % steps; |
||

1318 | v = v / steps; |
||

1319 | s->sb_samples[0][k * 12 + l + 0][i] = |
||

1320 | l2_unscale_group(steps, mant, scale0); |
||

1321 | s->sb_samples[1][k * 12 + l + 0][i] = |
||

1322 | l2_unscale_group(steps, mant, scale1); |
||

1323 | mant = v % steps; |
||

1324 | v = v / steps; |
||

1325 | s->sb_samples[0][k * 12 + l + 1][i] = |
||

1326 | l2_unscale_group(steps, mant, scale0); |
||

1327 | s->sb_samples[1][k * 12 + l + 1][i] = |
||

1328 | l2_unscale_group(steps, mant, scale1); |
||

1329 | s->sb_samples[0][k * 12 + l + 2][i] = |
||

1330 | l2_unscale_group(steps, v, scale0); |
||

1331 | s->sb_samples[1][k * 12 + l + 2][i] = |
||

1332 | l2_unscale_group(steps, v, scale1); |
||

1333 | ```
} else {
``` |
||

1334 | for(m=0;m<3;m++) { |
||

1335 | mant = get_bits(&s->gb, bits); |
||

1336 | s->sb_samples[0][k * 12 + l + m][i] = |
||

1337 | ```
l1_unscale(bits - 1, mant, scale0);
``` |
||

1338 | s->sb_samples[1][k * 12 + l + m][i] = |
||

1339 | ```
l1_unscale(bits - 1, mant, scale1);
``` |
||

1340 | } |
||

1341 | } |
||

1342 | ```
} else {
``` |
||

1343 | s->sb_samples[0][k * 12 + l + 0][i] = 0; |
||

1344 | s->sb_samples[0][k * 12 + l + 1][i] = 0; |
||

1345 | s->sb_samples[0][k * 12 + l + 2][i] = 0; |
||

1346 | s->sb_samples[1][k * 12 + l + 0][i] = 0; |
||

1347 | s->sb_samples[1][k * 12 + l + 1][i] = 0; |
||

1348 | s->sb_samples[1][k * 12 + l + 2][i] = 0; |
||

1349 | } |
||

1350 | ```
/* next subband in alloc table */
``` |
||

1351 | ```
j += 1 << bit_alloc_bits;
``` |
||

1352 | } |
||

1353 | ```
/* fill remaining samples to zero */
``` |
||

1354 | ```
for(i=sblimit;i<SBLIMIT;i++) {
``` |
||

1355 | for(ch=0;ch<s->nb_channels;ch++) { |
||

1356 | s->sb_samples[ch][k * 12 + l + 0][i] = 0; |
||

1357 | s->sb_samples[ch][k * 12 + l + 1][i] = 0; |
||

1358 | s->sb_samples[ch][k * 12 + l + 2][i] = 0; |
||

1359 | } |
||

1360 | } |
||

1361 | } |
||

1362 | } |
||

1363 | return 3 * 12; |
||

1364 | de6d9b64 | Fabrice Bellard | } |

1365 | |||

1366 | ```
/*
``` |
||

1367 | 239c2f4c | Fabrice Bellard | ```
* Seek back in the stream for backstep bytes (at most 511 bytes)
``` |

1368 | de6d9b64 | Fabrice Bellard | ```
*/
``` |

1369 | 239c2f4c | Fabrice Bellard | static void seek_to_maindata(MPADecodeContext *s, long backstep) |

1370 | de6d9b64 | Fabrice Bellard | { |

1371 | UINT8 *ptr; |
||

1372 | |||

1373 | ```
/* compute current position in stream */
``` |
||

1374 | 27a3e2c5 | Michael Niedermayer | ```
#ifdef ALT_BITSTREAM_READER
``` |

1375 | ```
ptr = s->gb.buffer + (s->gb.index>>3);
``` |
||

1376 | ```
#else
``` |
||

1377 | 239c2f4c | Fabrice Bellard | ```
ptr = s->gb.buf_ptr - (s->gb.bit_cnt >> 3);
``` |

1378 | 27a3e2c5 | Michael Niedermayer | ```
#endif
``` |

1379 | de6d9b64 | Fabrice Bellard | ```
/* copy old data before current one */
``` |

1380 | ptr -= backstep; |
||

1381 | 239c2f4c | Fabrice Bellard | ```
memcpy(ptr, s->inbuf1[s->inbuf_index ^ 1] +
``` |

1382 | BACKSTEP_SIZE + s->old_frame_size - backstep, backstep); |
||

1383 | de6d9b64 | Fabrice Bellard | ```
/* init get bits again */
``` |

1384 | 239c2f4c | Fabrice Bellard | init_get_bits(&s->gb, ptr, s->frame_size + backstep); |

1385 | de6d9b64 | Fabrice Bellard | |

1386 | 239c2f4c | Fabrice Bellard | ```
/* prepare next buffer */
``` |

1387 | ```
s->inbuf_index ^= 1;
``` |
||

1388 | s->inbuf = &s->inbuf1[s->inbuf_index][BACKSTEP_SIZE]; |
||

1389 | s->old_frame_size = s->frame_size; |
||

1390 | } |
||

1391 | |||

1392 | static inline void lsf_sf_expand(int *slen, |
||

1393 | int sf, int n1, int n2, int n3) |
||

1394 | { |
||

1395 | ```
if (n3) {
``` |
||

1396 | ```
slen[3] = sf % n3;
``` |
||

1397 | sf /= n3; |
||

1398 | ```
} else {
``` |
||

1399 | slen[3] = 0; |
||

1400 | } |
||

1401 | ```
if (n2) {
``` |
||

1402 | ```
slen[2] = sf % n2;
``` |
||

1403 | sf /= n2; |
||

1404 | ```
} else {
``` |
||

1405 | slen[2] = 0; |
||

1406 | } |
||

1407 | ```
slen[1] = sf % n1;
``` |
||

1408 | sf /= n1; |
||

1409 | ```
slen[0] = sf;
``` |
||

1410 | } |
||

1411 | |||

1412 | static void exponents_from_scale_factors(MPADecodeContext *s, |
||

1413 | GranuleDef *g, |
||

1414 | INT16 *exponents) |
||

1415 | { |
||

1416 | ```
const UINT8 *bstab, *pretab;
``` |
||

1417 | int len, i, j, k, l, v0, shift, gain, gains[3]; |
||

1418 | INT16 *exp_ptr; |
||

1419 | |||

1420 | exp_ptr = exponents; |
||

1421 | ```
gain = g->global_gain - 210;
``` |
||

1422 | ```
shift = g->scalefac_scale + 1;
``` |
||

1423 | |||

1424 | bstab = band_size_long[s->sample_rate_index]; |
||

1425 | pretab = mpa_pretab[g->preflag]; |
||

1426 | for(i=0;i<g->long_end;i++) { |
||

1427 | v0 = gain - ((g->scale_factors[i] + pretab[i]) << shift); |
||

1428 | len = bstab[i]; |
||

1429 | for(j=len;j>0;j--) |
||

1430 | *exp_ptr++ = v0; |
||

1431 | } |
||

1432 | |||

1433 | if (g->short_start < 13) { |
||

1434 | bstab = band_size_short[s->sample_rate_index]; |
||

1435 | gains[0] = gain - (g->subblock_gain[0] << 3); |
||

1436 | gains[1] = gain - (g->subblock_gain[1] << 3); |
||

1437 | gains[2] = gain - (g->subblock_gain[2] << 3); |
||

1438 | k = g->long_end; |
||

1439 | for(i=g->short_start;i<13;i++) { |
||

1440 | len = bstab[i]; |
||

1441 | for(l=0;l<3;l++) { |
||

1442 | v0 = gains[l] - (g->scale_factors[k++] << shift); |
||

1443 | for(j=len;j>0;j--) |
||

1444 | *exp_ptr++ = v0; |
||

1445 | } |
||

1446 | } |
||

1447 | } |
||

1448 | } |
||

1449 | |||

1450 | ```
/* handle n = 0 too */
``` |
||

1451 | static inline int get_bitsz(GetBitContext *s, int n) |
||

1452 | { |
||

1453 | if (n == 0) |
||

1454 | return 0; |
||

1455 | ```
else
``` |
||

1456 | ```
return get_bits(s, n);
``` |
||

1457 | } |
||

1458 | |||

1459 | static int huffman_decode(MPADecodeContext *s, GranuleDef *g, |
||

1460 | ```
INT16 *exponents, int end_pos)
``` |
||

1461 | { |
||

1462 | ```
int s_index;
``` |
||

1463 | ```
int linbits, code, x, y, l, v, i, j, k, pos;
``` |
||

1464 | UINT8 *last_buf_ptr; |
||

1465 | UINT32 last_bit_buf; |
||

1466 | ```
int last_bit_cnt;
``` |
||

1467 | VLC *vlc; |
||

1468 | UINT8 *code_table; |
||

1469 | |||

1470 | ```
/* low frequencies (called big values) */
``` |
||

1471 | ```
s_index = 0;
``` |
||

1472 | for(i=0;i<3;i++) { |
||

1473 | j = g->region_size[i]; |
||

1474 | if (j == 0) |
||

1475 | ```
continue;
``` |
||

1476 | ```
/* select vlc table */
``` |
||

1477 | k = g->table_select[i]; |
||

1478 | ```
l = mpa_huff_data[k][0];
``` |
||

1479 | ```
linbits = mpa_huff_data[k][1];
``` |
||

1480 | vlc = &huff_vlc[l]; |
||

1481 | code_table = huff_code_table[l]; |
||

1482 | |||

1483 | ```
/* read huffcode and compute each couple */
``` |
||

1484 | for(;j>0;j--) { |
||

1485 | ```
if (get_bits_count(&s->gb) >= end_pos)
``` |
||

1486 | ```
break;
``` |
||

1487 | ```
if (code_table) {
``` |
||

1488 | code = get_vlc(&s->gb, vlc); |
||

1489 | if (code < 0) |
||

1490 | return -1; |
||

1491 | y = code_table[code]; |
||

1492 | ```
x = y >> 4;
``` |
||

1493 | ```
y = y & 0x0f;
``` |
||

1494 | ```
} else {
``` |
||

1495 | ```
x = 0;
``` |
||

1496 | ```
y = 0;
``` |
||

1497 | } |
||

1498 | ```
dprintf("region=%d n=%d x=%d y=%d exp=%d\n",
``` |
||

1499 | i, g->region_size[i] - j, x, y, exponents[s_index]); |
||

1500 | ```
if (x) {
``` |
||

1501 | if (x == 15) |
||

1502 | x += get_bitsz(&s->gb, linbits); |
||

1503 | v = l3_unscale(x, exponents[s_index]); |
||

1504 | ```
if (get_bits1(&s->gb))
``` |
||

1505 | v = -v; |
||

1506 | ```
} else {
``` |
||

1507 | ```
v = 0;
``` |
||

1508 | } |
||

1509 | g->sb_hybrid[s_index++] = v; |
||

1510 | ```
if (y) {
``` |
||

1511 | if (y == 15) |
||

1512 | y += get_bitsz(&s->gb, linbits); |
||

1513 | v = l3_unscale(y, exponents[s_index]); |
||

1514 | ```
if (get_bits1(&s->gb))
``` |
||

1515 | v = -v; |
||

1516 | ```
} else {
``` |
||

1517 | ```
v = 0;
``` |
||

1518 | } |
||

1519 | g->sb_hybrid[s_index++] = v; |
||

1520 | } |
||

1521 | } |
||

1522 | |||

1523 | ```
/* high frequencies */
``` |
||

1524 | vlc = &huff_quad_vlc[g->count1table_select]; |
||

1525 | ```
last_buf_ptr = NULL;
``` |
||

1526 | ```
last_bit_buf = 0;
``` |
||

1527 | ```
last_bit_cnt = 0;
``` |
||

1528 | while (s_index <= 572) { |
||

1529 | pos = get_bits_count(&s->gb); |
||

1530 | ```
if (pos >= end_pos) {
``` |
||

1531 | if (pos > end_pos && last_buf_ptr != NULL) { |
||

1532 | ```
/* some encoders generate an incorrect size for this
``` |
||

1533 | ```
part. We must go back into the data */
``` |
||

1534 | ```
s_index -= 4;
``` |
||

1535 | 27a3e2c5 | Michael Niedermayer | ```
#ifdef ALT_BITSTREAM_READER
``` |

1536 | s->gb.buffer = last_buf_ptr; |
||

1537 | s->gb.index = last_bit_cnt; |
||

1538 | ```
#else
``` |
||

1539 | 239c2f4c | Fabrice Bellard | s->gb.buf_ptr = last_buf_ptr; |

1540 | s->gb.bit_buf = last_bit_buf; |
||

1541 | s->gb.bit_cnt = last_bit_cnt; |
||

1542 | 27a3e2c5 | Michael Niedermayer | ```
#endif
``` |

1543 | 239c2f4c | Fabrice Bellard | } |

1544 | ```
break;
``` |
||

1545 | } |
||

1546 | 27a3e2c5 | Michael Niedermayer | ```
#ifdef ALT_BITSTREAM_READER
``` |

1547 | last_buf_ptr = s->gb.buffer; |
||

1548 | last_bit_cnt = s->gb.index; |
||

1549 | ```
#else
``` |
||

1550 | 239c2f4c | Fabrice Bellard | last_buf_ptr = s->gb.buf_ptr; |

1551 | last_bit_buf = s->gb.bit_buf; |
||

1552 | last_bit_cnt = s->gb.bit_cnt; |
||

1553 | 27a3e2c5 | Michael Niedermayer | ```
#endif
``` |

1554 | 239c2f4c | Fabrice Bellard | |

1555 | code = get_vlc(&s->gb, vlc); |
||

1556 | ```
dprintf("t=%d code=%d\n", g->count1table_select, code);
``` |
||

1557 | if (code < 0) |
||

1558 | return -1; |
||

1559 | for(i=0;i<4;i++) { |
||

1560 | if (code & (8 >> i)) { |
||

1561 | ```
/* non zero value. Could use a hand coded function for
``` |
||

1562 | ```
'one' value */
``` |
||

1563 | ```
v = l3_unscale(1, exponents[s_index]);
``` |
||

1564 | ```
if(get_bits1(&s->gb))
``` |
||

1565 | v = -v; |
||

1566 | ```
} else {
``` |
||

1567 | ```
v = 0;
``` |
||

1568 | } |
||

1569 | g->sb_hybrid[s_index++] = v; |
||

1570 | } |
||

1571 | } |
||

1572 | while (s_index < 576) |
||

1573 | ```
g->sb_hybrid[s_index++] = 0;
``` |
||

1574 | de6d9b64 | Fabrice Bellard | return 0; |

1575 | } |
||

1576 | |||

1577 | 239c2f4c | Fabrice Bellard | ```
/* Reorder short blocks from bitstream order to interleaved order. It
``` |

1578 | ```
would be faster to do it in parsing, but the code would be far more
``` |
||

1579 | ```
complicated */
``` |
||

1580 | static void reorder_block(MPADecodeContext *s, GranuleDef *g) |
||

1581 | { |
||

1582 | ```
int i, j, k, len;
``` |
||

1583 | INT32 *ptr, *dst, *ptr1; |
||

1584 | ```
INT32 tmp[576];
``` |
||

1585 | |||

1586 | if (g->block_type != 2) |
||

1587 | ```
return;
``` |
||

1588 | |||

1589 | ```
if (g->switch_point) {
``` |
||

1590 | if (s->sample_rate_index != 8) { |
||

1591 | ```
ptr = g->sb_hybrid + 36;
``` |
||

1592 | ```
} else {
``` |
||

1593 | ```
ptr = g->sb_hybrid + 48;
``` |
||

1594 | } |
||

1595 | ```
} else {
``` |
||

1596 | ptr = g->sb_hybrid; |
||

1597 | } |
||

1598 | |||

1599 | for(i=g->short_start;i<13;i++) { |
||

1600 | len = band_size_short[s->sample_rate_index][i]; |
||

1601 | ptr1 = ptr; |
||

1602 | for(k=0;k<3;k++) { |
||

1603 | dst = tmp + k; |
||

1604 | for(j=len;j>0;j--) { |
||

1605 | *dst = *ptr++; |
||

1606 | ```
dst += 3;
``` |
||

1607 | } |
||

1608 | } |
||

1609 | memcpy(ptr1, tmp, len * 3 * sizeof(INT32)); |
||

1610 | } |
||

1611 | } |
||

1612 | |||

1613 | #define ISQRT2 FIXR(0.70710678118654752440) |
||

1614 | |||

1615 | static void compute_stereo(MPADecodeContext *s, |
||

1616 | GranuleDef *g0, GranuleDef *g1) |
||

1617 | { |
||

1618 | ```
int i, j, k, l;
``` |
||

1619 | INT32 v1, v2; |
||

1620 | ```
int sf_max, tmp0, tmp1, sf, len, non_zero_found;
``` |
||

1621 | ```
INT32 (*is_tab)[16];
``` |
||

1622 | INT32 *tab0, *tab1; |
||

1623 | int non_zero_found_short[3]; |
||

1624 | |||

1625 | ```
/* intensity stereo */
``` |
||

1626 | ```
if (s->mode_ext & MODE_EXT_I_STEREO) {
``` |
||

1627 | ```
if (!s->lsf) {
``` |
||

1628 | is_tab = is_table; |
||

1629 | ```
sf_max = 7;
``` |
||

1630 | ```
} else {
``` |
||

1631 | ```
is_tab = is_table_lsf[g1->scalefac_compress & 1];
``` |
||

1632 | ```
sf_max = 16;
``` |
||

1633 | } |
||

1634 | |||

1635 | ```
tab0 = g0->sb_hybrid + 576;
``` |
||

1636 | ```
tab1 = g1->sb_hybrid + 576;
``` |
||

1637 | |||

1638 | non_zero_found_short[0] = 0; |
||

1639 | non_zero_found_short[1] = 0; |
||

1640 | non_zero_found_short[2] = 0; |
||

1641 | k = (13 - g1->short_start) * 3 + g1->long_end - 3; |
||

1642 | for(i = 12;i >= g1->short_start;i--) { |
||

1643 | ```
/* for last band, use previous scale factor */
``` |
||

1644 | if (i != 11) |
||

1645 | ```
k -= 3;
``` |
||

1646 | len = band_size_short[s->sample_rate_index][i]; |
||

1647 | for(l=2;l>=0;l--) { |
||

1648 | tab0 -= len; |
||

1649 | tab1 -= len; |
||

1650 | ```
if (!non_zero_found_short[l]) {
``` |
||

1651 | ```
/* test if non zero band. if so, stop doing i-stereo */
``` |
||

1652 | for(j=0;j<len;j++) { |
||

1653 | if (tab1[j] != 0) { |
||

1654 | ```
non_zero_found_short[l] = 1;
``` |
||

1655 | ```
goto found1;
``` |
||

1656 | } |
||

1657 | } |
||

1658 | sf = g1->scale_factors[k + l]; |
||

1659 | ```
if (sf >= sf_max)
``` |
||

1660 | ```
goto found1;
``` |
||

1661 | |||

1662 | ```
v1 = is_tab[0][sf];
``` |
||

1663 | ```
v2 = is_tab[1][sf];
``` |
||

1664 | for(j=0;j<len;j++) { |
||

1665 | tmp0 = tab0[j]; |
||

1666 | tab0[j] = MULL(tmp0, v1); |
||

1667 | tab1[j] = MULL(tmp0, v2); |
||

1668 | } |
||

1669 | ```
} else {
``` |
||

1670 | ```
found1:
``` |
||

1671 | ```
if (s->mode_ext & MODE_EXT_MS_STEREO) {
``` |
||

1672 | ```
/* lower part of the spectrum : do ms stereo
``` |
||

1673 | ```
if enabled */
``` |
||

1674 | for(j=0;j<len;j++) { |
||

1675 | tmp0 = tab0[j]; |
||

1676 | tmp1 = tab1[j]; |
||

1677 | tab0[j] = MULL(tmp0 + tmp1, ISQRT2); |
||

1678 | tab1[j] = MULL(tmp0 - tmp1, ISQRT2); |
||

1679 | } |
||

1680 | } |
||

1681 | } |
||

1682 | } |
||

1683 | } |
||

1684 | |||

1685 | ```
non_zero_found = non_zero_found_short[0] |
``` |
||

1686 | ```
non_zero_found_short[1] |
``` |
||

1687 | ```
non_zero_found_short[2];
``` |
||

1688 | |||

1689 | for(i = g1->long_end - 1;i >= 0;i--) { |
||

1690 | len = band_size_long[s->sample_rate_index][i]; |
||

1691 | tab0 -= len; |
||

1692 | tab1 -= len; |
||

1693 | ```
/* test if non zero band. if so, stop doing i-stereo */
``` |
||

1694 | ```
if (!non_zero_found) {
``` |
||

1695 | for(j=0;j<len;j++) { |
||

1696 | if (tab1[j] != 0) { |
||

1697 | ```
non_zero_found = 1;
``` |
||

1698 | ```
goto found2;
``` |
||

1699 | } |
||

1700 | } |
||

1701 | ```
/* for last band, use previous scale factor */
``` |
||

1702 | k = (i == 21) ? 20 : i; |
||

1703 | sf = g1->scale_factors[k]; |
||

1704 | ```
if (sf >= sf_max)
``` |
||

1705 | ```
goto found2;
``` |
||

1706 | ```
v1 = is_tab[0][sf];
``` |
||

1707 | ```
v2 = is_tab[1][sf];
``` |
||

1708 | for(j=0;j<len;j++) { |
||

1709 | tmp0 = tab0[j]; |
||

1710 | tab0[j] = MULL(tmp0, v1); |
||

1711 | tab1[j] = MULL(tmp0, v2); |
||

1712 | } |
||

1713 | ```
} else {
``` |
||

1714 | ```
found2:
``` |
||

1715 | ```
if (s->mode_ext & MODE_EXT_MS_STEREO) {
``` |
||

1716 | ```
/* lower part of the spectrum : do ms stereo
``` |
||

1717 | ```
if enabled */
``` |
||

1718 | for(j=0;j<len;j++) { |
||

1719 | tmp0 = tab0[j]; |
||

1720 | tmp1 = tab1[j]; |
||

1721 | tab0[j] = MULL(tmp0 + tmp1, ISQRT2); |
||

1722 | tab1[j] = MULL(tmp0 - tmp1, ISQRT2); |
||

1723 | } |
||

1724 | } |
||

1725 | } |
||

1726 | } |
||

1727 | } else if (s->mode_ext & MODE_EXT_MS_STEREO) { |
||

1728 | ```
/* ms stereo ONLY */
``` |
||

1729 | ```
/* NOTE: the 1/sqrt(2) normalization factor is included in the
``` |
||

1730 | ```
global gain */
``` |
||

1731 | tab0 = g0->sb_hybrid; |
||

1732 | tab1 = g1->sb_hybrid; |
||

1733 | for(i=0;i<576;i++) { |
||

1734 | tmp0 = tab0[i]; |
||

1735 | tmp1 = tab1[i]; |
||

1736 | tab0[i] = tmp0 + tmp1; |
||

1737 | tab1[i] = tmp0 - tmp1; |
||

1738 | } |
||

1739 | } |
||

1740 | } |
||

1741 | |||

1742 | static void compute_antialias(MPADecodeContext *s, |
||

1743 | GranuleDef *g) |
||

1744 | { |
||

1745 | INT32 *ptr, *p0, *p1, *csa; |
||

1746 | ```
int n, tmp0, tmp1, i, j;
``` |
||

1747 | |||

1748 | ```
/* we antialias only "long" bands */
``` |
||

1749 | if (g->block_type == 2) { |
||

1750 | ```
if (!g->switch_point)
``` |
||

1751 | ```
return;
``` |
||

1752 | ```
/* XXX: check this for 8000Hz case */
``` |
||

1753 | ```
n = 1;
``` |
||

1754 | ```
} else {
``` |
||

1755 | ```
n = SBLIMIT - 1;
``` |
||

1756 | } |
||

1757 | |||

1758 | ```
ptr = g->sb_hybrid + 18;
``` |
||

1759 | for(i = n;i > 0;i--) { |
||

1760 | ```
p0 = ptr - 1;
``` |
||

1761 | p1 = ptr; |
||

1762 | csa = &csa_table[0][0]; |
||

1763 | for(j=0;j<8;j++) { |
||

1764 | tmp0 = *p0; |
||

1765 | tmp1 = *p1; |
||

1766 | *p0 = FRAC_RND(MUL64(tmp0, csa[0]) - MUL64(tmp1, csa[1])); |
||

1767 | *p1 = FRAC_RND(MUL64(tmp0, csa[1]) + MUL64(tmp1, csa[0])); |
||

1768 | p0--; |
||

1769 | p1++; |
||

1770 | ```
csa += 2;
``` |
||

1771 | } |
||

1772 | ```
ptr += 18;
``` |
||

1773 | } |
||

1774 | } |
||

1775 | |||

1776 | static void compute_imdct(MPADecodeContext *s, |
||

1777 | GranuleDef *g, |
||

1778 | INT32 *sb_samples, |
||

1779 | INT32 *mdct_buf) |
||

1780 | { |
||

1781 | INT32 *ptr, *win, *win1, *buf, *buf2, *out_ptr, *ptr1; |
||

1782 | ```
INT32 in[6];
``` |
||

1783 | ```
INT32 out[36];
``` |
||

1784 | ```
INT32 out2[12];
``` |
||

1785 | ```
int i, j, k, mdct_long_end, v, sblimit;
``` |
||

1786 | |||

1787 | ```
/* find last non zero block */
``` |
||

1788 | ```
ptr = g->sb_hybrid + 576;
``` |
||

1789 | ptr1 = g->sb_hybrid + 2 * 18; |
||

1790 | ```
while (ptr >= ptr1) {
``` |
||

1791 | ```
ptr -= 6;
``` |
||

1792 | v = ptr[0] | ptr[1] | ptr[2] | ptr[3] | ptr[4] | ptr[5]; |
||

1793 | if (v != 0) |
||

1794 | ```
break;
``` |
||

1795 | } |
||

1796 | sblimit = ((ptr - g->sb_hybrid) / 18) + 1; |
||

1797 | |||

1798 | if (g->block_type == 2) { |
||

1799 | ```
/* XXX: check for 8000 Hz */
``` |
||

1800 | ```
if (g->switch_point)
``` |
||

1801 | ```
mdct_long_end = 2;
``` |
||

1802 | ```
else
``` |
||

1803 | ```
mdct_long_end = 0;
``` |
||

1804 | ```
} else {
``` |
||

1805 | mdct_long_end = sblimit; |
||

1806 | } |
||

1807 | |||

1808 | buf = mdct_buf; |
||

1809 | ptr = g->sb_hybrid; |
||

1810 | for(j=0;j<mdct_long_end;j++) { |
||

1811 | imdct36(out, ptr); |
||

1812 | ```
/* apply window & overlap with previous buffer */
``` |
||

1813 | out_ptr = sb_samples + j; |
||

1814 | ```
/* select window */
``` |
||

1815 | if (g->switch_point && j < 2) |
||

1816 | ```
win1 = mdct_win[0];
``` |
||

1817 | ```
else
``` |
||

1818 | win1 = mdct_win[g->block_type]; |
||

1819 | ```
/* select frequency inversion */
``` |
||

1820 | win = win1 + ((4 * 36) & -(j & 1)); |
||

1821 | for(i=0;i<18;i++) { |
||

1822 | *out_ptr = MULL(out[i], win[i]) + buf[i]; |
||

1823 | buf[i] = MULL(out[i + 18], win[i + 18]); |
||

1824 | out_ptr += SBLIMIT; |
||

1825 | } |
||

1826 | ```
ptr += 18;
``` |
||

1827 | ```
buf += 18;
``` |
||

1828 | } |
||

1829 | ```
for(j=mdct_long_end;j<sblimit;j++) {
``` |
||

1830 | for(i=0;i<6;i++) { |
||

1831 | ```
out[i] = 0;
``` |
||

1832 | out[6 + i] = 0; |
||

1833 | out[30+i] = 0; |
||

1834 | } |
||

1835 | ```
/* select frequency inversion */
``` |
||

1836 | win = mdct_win[2] + ((4 * 36) & -(j & 1)); |
||

1837 | ```
buf2 = out + 6;
``` |
||

1838 | for(k=0;k<3;k++) { |
||

1839 | ```
/* reorder input for short mdct */
``` |
||

1840 | ptr1 = ptr + k; |
||

1841 | for(i=0;i<6;i++) { |
||

1842 | in[i] = *ptr1; |
||

1843 | ```
ptr1 += 3;
``` |
||

1844 | } |
||

1845 | imdct12(out2, in); |
||

1846 | ```
/* apply 12 point window and do small overlap */
``` |
||

1847 | for(i=0;i<6;i++) { |
||

1848 | buf2[i] = MULL(out2[i], win[i]) + buf2[i]; |
||

1849 | buf2[i + 6] = MULL(out2[i + 6], win[i + 6]); |
||

1850 | } |
||

1851 | ```
buf2 += 6;
``` |
||

1852 | } |
||

1853 | ```
/* overlap */
``` |
||

1854 | out_ptr = sb_samples + j; |
||

1855 | for(i=0;i<18;i++) { |
||

1856 | *out_ptr = out[i] + buf[i]; |
||

1857 | ```
buf[i] = out[i + 18];
``` |
||

1858 | out_ptr += SBLIMIT; |
||

1859 | } |
||

1860 | ```
ptr += 18;
``` |
||

1861 | ```
buf += 18;
``` |
||

1862 | } |
||

1863 | ```
/* zero bands */
``` |
||

1864 | ```
for(j=sblimit;j<SBLIMIT;j++) {
``` |
||

1865 | ```
/* overlap */
``` |
||

1866 | out_ptr = sb_samples + j; |
||

1867 | for(i=0;i<18;i++) { |
||

1868 | *out_ptr = buf[i]; |
||

1869 | ```
buf[i] = 0;
``` |
||

1870 | out_ptr += SBLIMIT; |
||

1871 | } |
||

1872 | ```
buf += 18;
``` |
||

1873 | } |
||

1874 | } |
||

1875 | |||

1876 | ```
#ifdef DEBUG
``` |
||

1877 | void sample_dump(int fnum, INT32 *tab, int n) |
||

1878 | { |
||

1879 | static FILE *files[16], *f; |
||

1880 | char buf[512]; |
||

1881 | |||

1882 | f = files[fnum]; |
||

1883 | ```
if (!f) {
``` |
||

1884 | ```
sprintf(buf, "/tmp/out%d.pcm", fnum);
``` |
||

1885 | ```
f = fopen(buf, "w");
``` |
||

1886 | ```
if (!f)
``` |
||

1887 | ```
return;
``` |
||

1888 | files[fnum] = f; |
||

1889 | } |
||

1890 | |||

1891 | if (fnum == 0) { |
||

1892 | ```
int i;
``` |
||

1893 | static int pos = 0; |
||

1894 | ```
printf("pos=%d\n", pos);
``` |
||

1895 | for(i=0;i<n;i++) { |
||

1896 | printf(" %f", (double)tab[i] / 32768.0); |
||

1897 | if ((i % 18) == 17) |
||

1898 | ```
printf("\n");
``` |
||

1899 | } |
||

1900 | pos += n; |
||

1901 | } |
||

1902 | |||

1903 | fwrite(tab, 1, n * sizeof(INT32), f); |
||

1904 | } |
||

1905 | ```
#endif
``` |
||

1906 | |||

1907 | |||

1908 | ```
/* main layer3 decoding function */
``` |
||

1909 | static int mp_decode_layer3(MPADecodeContext *s) |
||

1910 | { |
||

1911 | ```
int nb_granules, main_data_begin, private_bits;
``` |
||

1912 | ```
int gr, ch, blocksplit_flag, i, j, k, n, bits_pos, bits_left;
``` |
||

1913 | GranuleDef granules[2][2], *g; |
||

1914 | ```
INT16 exponents[576];
``` |
||

1915 | |||

1916 | ```
/* read side info */
``` |
||

1917 | ```
if (s->lsf) {
``` |
||

1918 | ```
main_data_begin = get_bits(&s->gb, 8);
``` |
||

1919 | if (s->nb_channels == 2) |
||

1920 | ```
private_bits = get_bits(&s->gb, 2);
``` |
||

1921 | ```
else
``` |
||

1922 | ```
private_bits = get_bits(&s->gb, 1);
``` |
||

1923 | ```
nb_granules = 1;
``` |
||

1924 | ```
} else {
``` |
||

1925 | ```
main_data_begin = get_bits(&s->gb, 9);
``` |
||

1926 | if (s->nb_channels == 2) |
||

1927 | ```
private_bits = get_bits(&s->gb, 3);
``` |
||

1928 | ```
else
``` |
||

1929 | ```
private_bits = get_bits(&s->gb, 5);
``` |
||

1930 | ```
nb_granules = 2;
``` |
||

1931 | for(ch=0;ch<s->nb_channels;ch++) { |
||

1932 | granules[ch][0].scfsi = 0; /* all scale factors are transmitted */ |
||

1933 | granules[ch][1].scfsi = get_bits(&s->gb, 4); |
||

1934 | } |
||

1935 | } |
||

1936 | |||

1937 | for(gr=0;gr<nb_granules;gr++) { |
||

1938 | for(ch=0;ch<s->nb_channels;ch++) { |
||

1939 | ```
dprintf("gr=%d ch=%d: side_info\n", gr, ch);
``` |
||

1940 | g = &granules[ch][gr]; |
||

1941 | ```
g->part2_3_length = get_bits(&s->gb, 12);
``` |
||

1942 | ```
g->big_values = get_bits(&s->gb, 9);
``` |
||

1943 | ```
g->global_gain = get_bits(&s->gb, 8);
``` |
||

1944 | ```
/* if MS stereo only is selected, we precompute the
``` |
||

1945 | ```
1/sqrt(2) renormalization factor */
``` |
||

1946 | ```
if ((s->mode_ext & (MODE_EXT_MS_STEREO | MODE_EXT_I_STEREO)) ==
``` |
||

1947 | MODE_EXT_MS_STEREO) |
||

1948 | ```
g->global_gain -= 2;
``` |
||

1949 | ```
if (s->lsf)
``` |
||

1950 | ```
g->scalefac_compress = get_bits(&s->gb, 9);
``` |
||

1951 | ```
else
``` |
||

1952 | ```
g->scalefac_compress = get_bits(&s->gb, 4);
``` |
||

1953 | ```
blocksplit_flag = get_bits(&s->gb, 1);
``` |
||

1954 | ```
if (blocksplit_flag) {
``` |
||

1955 | ```
g->block_type = get_bits(&s->gb, 2);
``` |
||

1956 | if (g->block_type == 0) |
||

1957 | return -1; |
||

1958 | ```
g->switch_point = get_bits(&s->gb, 1);
``` |
||

1959 | for(i=0;i<2;i++) |
||

1960 | ```
g->table_select[i] = get_bits(&s->gb, 5);
``` |
||

1961 | for(i=0;i<3;i++) |
||

1962 | ```
g->subblock_gain[i] = get_bits(&s->gb, 3);
``` |
||

1963 | ```
/* compute huffman coded region sizes */
``` |
||

1964 | if (g->block_type == 2) |
||

1965 | g->region_size[0] = (36 / 2); |
||

1966 | ```
else {
``` |
||

1967 | if (s->sample_rate_index <= 2) |
||

1968 | g->region_size[0] = (36 / 2); |
||

1969 | else if (s->sample_rate_index != 8) |
||

1970 | g->region_size[0] = (54 / 2); |
||

1971 | ```
else
``` |
||

1972 | g->region_size[0] = (108 / 2); |
||

1973 | } |
||

1974 | g->region_size[1] = (576 / 2); |
||

1975 | ```
} else {
``` |
||

1976 | ```
int region_address1, region_address2, l;
``` |
||

1977 | ```
g->block_type = 0;
``` |
||

1978 | ```
g->switch_point = 0;
``` |
||

1979 | for(i=0;i<3;i++) |
||

1980 | ```
g->table_select[i] = get_bits(&s->gb, 5);
``` |
||

1981 | ```
/* compute huffman coded region sizes */
``` |
||

1982 | ```
region_address1 = get_bits(&s->gb, 4);
``` |
||

1983 | ```
region_address2 = get_bits(&s->gb, 3);
``` |
||

1984 | ```
dprintf("region1=%d region2=%d\n",
``` |
||

1985 | region_address1, region_address2); |
||

1986 | ```
g->region_size[0] =
``` |
||

1987 | band_index_long[s->sample_rate_index][region_address1 + 1] >> 1; |
||

1988 | ```
l = region_address1 + region_address2 + 2;
``` |
||

1989 | ```
/* should not overflow */
``` |
||

1990 | if (l > 22) |
||

1991 | ```
l = 22;
``` |
||

1992 | ```
g->region_size[1] =
``` |
||

1993 | ```
band_index_long[s->sample_rate_index][l] >> 1;
``` |
||

1994 | } |
||

1995 | ```
/* convert region offsets to region sizes and truncate
``` |
||

1996 | ```
size to big_values */
``` |
||

1997 | g->region_size[2] = (576 / 2); |
||

1998 | ```
j = 0;
``` |
||

1999 | for(i=0;i<3;i++) { |
||

2000 | k = g->region_size[i]; |
||

2001 | ```
if (k > g->big_values)
``` |
||

2002 | k = g->big_values; |
||

2003 | g->region_size[i] = k - j; |
||

2004 | j = k; |
||

2005 | } |
||

2006 | |||

2007 | ```
/* compute band indexes */
``` |
||

2008 | if (g->block_type == 2) { |
||

2009 | ```
if (g->switch_point) {
``` |
||

2010 | ```
/* if switched mode, we handle the 36 first samples as
``` |
||

2011 | ```
long blocks. For 8000Hz, we handle the 48 first
``` |
||

2012 | ```
exponents as long blocks (XXX: check this!) */
``` |
||

2013 | if (s->sample_rate_index <= 2) |
||

2014 | ```
g->long_end = 8;
``` |
||

2015 | else if (s->sample_rate_index != 8) |
||

2016 | ```
g->long_end = 6;
``` |
||

2017 | ```
else
``` |
||

2018 | g->long_end = 4; /* 8000 Hz */ |
||

2019 | |||

2020 | if (s->sample_rate_index != 8) |
||

2021 | ```
g->short_start = 3;
``` |
||

2022 | ```
else
``` |
||

2023 | ```
g->short_start = 2;
``` |
||

2024 | ```
} else {
``` |
||

2025 | ```
g->long_end = 0;
``` |
||

2026 | ```
g->short_start = 0;
``` |
||

2027 | } |
||

2028 | ```
} else {
``` |
||

2029 | ```
g->short_start = 13;
``` |
||

2030 | ```
g->long_end = 22;
``` |
||

2031 | } |
||

2032 | |||

2033 | ```
g->preflag = 0;
``` |
||

2034 | ```
if (!s->lsf)
``` |
||

2035 | ```
g->preflag = get_bits(&s->gb, 1);
``` |
||

2036 | ```
g->scalefac_scale = get_bits(&s->gb, 1);
``` |
||

2037 | ```
g->count1table_select = get_bits(&s->gb, 1);
``` |
||

2038 | ```
dprintf("block_type=%d switch_point=%d\n",
``` |
||

2039 | g->block_type, g->switch_point); |
||

2040 | } |
||

2041 | } |
||

2042 | |||

2043 | ```
/* now we get bits from the main_data_begin offset */
``` |
||

2044 | ```
dprintf("seekback: %d\n", main_data_begin);
``` |
||

2045 | seek_to_maindata(s, main_data_begin); |
||

2046 | |||

2047 | for(gr=0;gr<nb_granules;gr++) { |
||

2048 | for(ch=0;ch<s->nb_channels;ch++) { |
||

2049 | g = &granules[ch][gr]; |
||

2050 | |||

2051 | bits_pos = get_bits_count(&s->gb); |
||

2052 | |||

2053 | ```
if (!s->lsf) {
``` |
||

2054 | UINT8 *sc; |
||

2055 | ```
int slen, slen1, slen2;
``` |
||

2056 | |||

2057 | ```
/* MPEG1 scale factors */
``` |
||

2058 | ```
slen1 = slen_table[0][g->scalefac_compress];
``` |
||

2059 | ```
slen2 = slen_table[1][g->scalefac_compress];
``` |
||

2060 | ```
dprintf("slen1=%d slen2=%d\n", slen1, slen2);
``` |
||

2061 | if (g->block_type == 2) { |
||

2062 | n = g->switch_point ? 17 : 18; |
||

2063 | ```
j = 0;
``` |
||

2064 | for(i=0;i<n;i++) |
||

2065 | g->scale_factors[j++] = get_bitsz(&s->gb, slen1); |
||

2066 | for(i=0;i<18;i++) |
||

2067 | g->scale_factors[j++] = get_bitsz(&s->gb, slen2); |
||

2068 | for(i=0;i<3;i++) |
||

2069 | ```
g->scale_factors[j++] = 0;
``` |
||

2070 | ```
} else {
``` |
||

2071 | ```
sc = granules[ch][0].scale_factors;
``` |
||

2072 | ```
j = 0;
``` |
||

2073 | for(k=0;k<4;k++) { |
||

2074 | n = (k == 0 ? 6 : 5); |
||

2075 | if ((g->scfsi & (0x8 >> k)) == 0) { |
||

2076 | ```
slen = (k < 2) ? slen1 : slen2;
``` |
||

2077 | for(i=0;i<n;i++) |
||

2078 | g->scale_factors[j++] = get_bitsz(&s->gb, slen); |
||

2079 | ```
} else {
``` |
||

2080 | ```
/* simply copy from last granule */
``` |
||

2081 | for(i=0;i<n;i++) { |
||

2082 | g->scale_factors[j] = sc[j]; |
||

2083 | j++; |
||

2084 | } |
||

2085 | } |
||

2086 | } |
||

2087 | ```
g->scale_factors[j++] = 0;
``` |
||

2088 | } |
||

2089 | ```
#ifdef DEBUG
``` |
||

2090 | { |
||

2091 | ```
printf("scfsi=%x gr=%d ch=%d scale_factors:\n",
``` |
||

2092 | g->scfsi, gr, ch); |
||

2093 | for(i=0;i<j;i++) |
||

2094 | ```
printf(" %d", g->scale_factors[i]);
``` |
||

2095 | ```
printf("\n");
``` |
||

2096 | } |
||

2097 | ```
#endif
``` |
||

2098 | ```
} else {
``` |
||

2099 | int tindex, tindex2, slen[4], sl, sf; |
||

2100 | |||

2101 | ```
/* LSF scale factors */
``` |
||

2102 | if (g->block_type == 2) { |
||

2103 | tindex = g->switch_point ? 2 : 1; |
||

2104 | ```
} else {
``` |
||

2105 | ```
tindex = 0;
``` |
||

2106 | } |
||

2107 | sf = g->scalefac_compress; |
||

2108 | if ((s->mode_ext & MODE_EXT_I_STEREO) && ch == 1) { |
||

2109 | ```
/* intensity stereo case */
``` |
||

2110 | ```
sf >>= 1;
``` |
||

2111 | if (sf < 180) { |
||

2112 | lsf_sf_expand(slen, sf, 6, 6, 0); |
||

2113 | ```
tindex2 = 3;
``` |
||

2114 | } else if (sf < 244) { |
||

2115 | lsf_sf_expand(slen, sf - 180, 4, 4, 0); |
||

2116 | ```
tindex2 = 4;
``` |
||

2117 | ```
} else {
``` |
||

2118 | lsf_sf_expand(slen, sf - 244, 3, 0, 0); |
||

2119 | ```
tindex2 = 5;
``` |
||

2120 | } |
||

2121 | ```
} else {
``` |
||

2122 | ```
/* normal case */
``` |
||

2123 | if (sf < 400) { |
||

2124 | lsf_sf_expand(slen, sf, 5, 4, 4); |
||

2125 | ```
tindex2 = 0;
``` |
||

2126 | } else if (sf < 500) { |
||

2127 | lsf_sf_expand(slen, sf - 400, 5, 4, 0); |
||

2128 | ```
tindex2 = 1;
``` |
||

2129 | ```
} else {
``` |
||

2130 | lsf_sf_expand(slen, sf - 500, 3, 0, 0); |
||

2131 | ```
tindex2 = 2;
``` |
||

2132 | ```
g->preflag = 1;
``` |
||

2133 | } |
||

2134 | } |
||

2135 | |||

2136 | ```
j = 0;
``` |
||

2137 | for(k=0;k<4;k++) { |
||

2138 | n = lsf_nsf_table[tindex2][tindex][k]; |
||

2139 | sl = slen[k]; |
||

2140 | for(i=0;i<n;i++) |
||

2141 | g->scale_factors[j++] = get_bitsz(&s->gb, sl); |
||

2142 | } |
||

2143 | ```
/* XXX: should compute exact size */
``` |
||

2144 | for(;j<40;j++) |
||

2145 | ```
g->scale_factors[j] = 0;
``` |
||

2146 | ```
#ifdef DEBUG
``` |
||

2147 | { |
||

2148 | ```
printf("gr=%d ch=%d scale_factors:\n",
``` |
||

2149 | gr, ch); |
||

2150 | for(i=0;i<40;i++) |
||

2151 | ```
printf(" %d", g->scale_factors[i]);
``` |
||

2152 | ```
printf("\n");
``` |
||

2153 | } |
||

2154 | ```
#endif
``` |
||

2155 | } |
||

2156 | |||

2157 | exponents_from_scale_factors(s, g, exponents); |
||

2158 | |||

2159 | ```
/* read Huffman coded residue */
``` |
||

2160 | ```
if (huffman_decode(s, g, exponents,
``` |
||

2161 | ```
bits_pos + g->part2_3_length) < 0)
``` |
||

2162 | return -1; |
||

2163 | #if defined(DEBUG) && 0 |
||

2164 | sample_dump(3, g->sb_hybrid, 576); |
||

2165 | ```
#endif
``` |
||

2166 | |||

2167 | ```
/* skip extension bits */
``` |
||

2168 | bits_left = g->part2_3_length - (get_bits_count(&s->gb) - bits_pos); |
||

2169 | if (bits_left < 0) { |
||

2170 | ```
dprintf("bits_left=%d\n", bits_left);
``` |
||

2171 | return -1; |
||

2172 | } |
||

2173 | while (bits_left >= 16) { |
||

2174 | ```
skip_bits(&s->gb, 16);
``` |
||

2175 | ```
bits_left -= 16;
``` |
||

2176 | } |
||

2177 | if (bits_left > 0) |
||

2178 | skip_bits(&s->gb, bits_left); |
||

2179 | ```
} /* ch */
``` |
||

2180 | |||

2181 | if (s->nb_channels == 2) |
||

2182 | compute_stereo(s, &granules[0][gr], &granules[1][gr]); |
||

2183 | |||

2184 | for(ch=0;ch<s->nb_channels;ch++) { |
||

2185 | g = &granules[ch][gr]; |
||

2186 | |||

2187 | reorder_block(s, g); |
||

2188 | ```
#ifdef DEBUG
``` |
||

2189 | sample_dump(0, g->sb_hybrid, 576); |
||

2190 | ```
#endif
``` |
||

2191 | compute_antialias(s, g); |
||

2192 | ```
#ifdef DEBUG
``` |
||

2193 | sample_dump(1, g->sb_hybrid, 576); |
||

2194 | ```
#endif
``` |
||

2195 | compute_imdct(s, g, &s->sb_samples[ch][18 * gr][0], s->mdct_buf[ch]); |
||

2196 | ```
#ifdef DEBUG
``` |
||

2197 | sample_dump(2, &s->sb_samples[ch][18 * gr][0], 576); |
||

2198 | ```
#endif
``` |
||

2199 | } |
||

2200 | ```
} /* gr */
``` |
||

2201 | return nb_granules * 18; |
||

2202 | } |
||

2203 | |||

2204 | static int mp_decode_frame(MPADecodeContext *s, |
||

2205 | ```
short *samples)
``` |
||

2206 | { |
||

2207 | ```
int i, nb_frames, ch;
``` |
||

2208 | ```
short *samples_ptr;
``` |
||

2209 | |||

2210 | init_get_bits(&s->gb, s->inbuf + HEADER_SIZE, |
||

2211 | s->inbuf_ptr - s->inbuf - HEADER_SIZE); |
||

2212 | |||

2213 | ```
/* skip error protection field */
``` |
||

2214 | ```
if (s->error_protection)
``` |
||

2215 | ```
get_bits(&s->gb, 16);
``` |
||

2216 | |||

2217 | ```
dprintf("frame %d:\n", s->frame_count);
``` |
||

2218 | ```
switch(s->layer) {
``` |
||

2219 | case 1: |
||

2220 | nb_frames = mp_decode_layer1(s); |
||

2221 | ```
break;
``` |
||

2222 | case 2: |
||

2223 | nb_frames = mp_decode_layer2(s); |
||

2224 | ```
break;
``` |
||

2225 | case 3: |
||

2226 | ```
default:
``` |
||

2227 | nb_frames = mp_decode_layer3(s); |
||

2228 | ```
break;
``` |
||

2229 | } |
||

2230 | ```
#if defined(DEBUG)
``` |
||

2231 | for(i=0;i<nb_frames;i++) { |
||

2232 | for(ch=0;ch<s->nb_channels;ch++) { |
||

2233 | ```
int j;
``` |
||

2234 | ```
printf("%d-%d:", i, ch);
``` |
||

2235 | for(j=0;j<SBLIMIT;j++) |
||

2236 | printf(" %0.6f", (double)s->sb_samples[ch][i][j] / FRAC_ONE); |
||

2237 | ```
printf("\n");
``` |
||

2238 | } |
||

2239 | } |
||

2240 | ```
#endif
``` |
||

2241 | ```
/* apply the synthesis filter */
``` |
||

2242 | for(ch=0;ch<s->nb_channels;ch++) { |
||

2243 | samples_ptr = samples + ch; |
||

2244 | for(i=0;i<nb_frames;i++) { |
||

2245 | synth_filter(s, ch, samples_ptr, s->nb_channels, |
||

2246 | s->sb_samples[ch][i]); |
||

2247 | ```
samples_ptr += 32 * s->nb_channels;
``` |
||

2248 | } |
||

2249 | } |
||

2250 | ```
#ifdef DEBUG
``` |
||

2251 | s->frame_count++; |
||

2252 | ```
#endif
``` |
||

2253 | return nb_frames * 32 * sizeof(short) * s->nb_channels; |
||

2254 | } |
||

2255 | |||

2256 | de6d9b64 | Fabrice Bellard | static int decode_frame(AVCodecContext * avctx, |

2257 | void *data, int *data_size, |
||

2258 | ```
UINT8 * buf, int buf_size)
``` |
||

2259 | { |
||

2260 | MPADecodeContext *s = avctx->priv_data; |
||

2261 | UINT32 header; |
||

2262 | UINT8 *buf_ptr; |
||

2263 | ```
int len, out_size;
``` |
||

2264 | ```
short *out_samples = data;
``` |
||

2265 | |||

2266 | ```
*data_size = 0;
``` |
||

2267 | buf_ptr = buf; |
||

2268 | while (buf_size > 0) { |
||

2269 | len = s->inbuf_ptr - s->inbuf; |
||

2270 | if (s->frame_size == 0) { |
||

2271 | 239c2f4c | Fabrice Bellard | ```
/* special case for next header for first frame in free
``` |

2272 | ```
format case (XXX: find a simpler method) */
``` |
||

2273 | if (s->free_format_next_header != 0) { |
||

2274 | s->inbuf[0] = s->free_format_next_header >> 24; |
||

2275 | s->inbuf[1] = s->free_format_next_header >> 16; |
||

2276 | s->inbuf[2] = s->free_format_next_header >> 8; |
||

2277 | ```
s->inbuf[3] = s->free_format_next_header;
``` |
||

2278 | ```
s->inbuf_ptr = s->inbuf + 4;
``` |
||

2279 | ```
s->free_format_next_header = 0;
``` |
||

2280 | ```
goto got_header;
``` |
||

2281 | } |
||

2282 | ```
/* no header seen : find one. We need at least HEADER_SIZE
``` |
||

2283 | ```
bytes to parse it */
``` |
||

2284 | de6d9b64 | Fabrice Bellard | len = HEADER_SIZE - len; |

2285 | ```
if (len > buf_size)
``` |
||

2286 | len = buf_size; |
||

2287 | 92d24f49 | Zdenek Kabelac | if (len > 0) { |

2288 | 2d83f323 | Zdenek Kabelac | memcpy(s->inbuf_ptr, buf_ptr, len); |

2289 | buf_ptr += len; |
||

2290 | buf_size -= len; |
||

2291 | c152c983 | Zdenek Kabelac | s->inbuf_ptr += len; |

2292 | } |
||

2293 | ```
if ((s->inbuf_ptr - s->inbuf) >= HEADER_SIZE) {
``` |
||

2294 | 239c2f4c | Fabrice Bellard | ```
got_header:
``` |

2295 | de6d9b64 | Fabrice Bellard | header = (s->inbuf[0] << 24) | (s->inbuf[1] << 16) | |

2296 | (s->inbuf[2] << 8) | s->inbuf[3]; |
||

2297 | 92d24f49 | Zdenek Kabelac | |

2298 | de6d9b64 | Fabrice Bellard | if (check_header(header) < 0) { |

2299 | ```
/* no sync found : move by one byte (inefficient, but simple!) */
``` |
||

2300 | 2d83f323 | Zdenek Kabelac | memcpy(s->inbuf, s->inbuf + 1, s->inbuf_ptr - s->inbuf - 1); |

2301 | de6d9b64 | Fabrice Bellard | s->inbuf_ptr--; |

2302 | 239c2f4c | Fabrice Bellard | ```
dprintf("skip %x\n", header);
``` |

2303 | ```
/* reset free format frame size to give a chance
``` |
||

2304 | ```
to get a new bitrate */
``` |
||

2305 | ```
s->free_format_frame_size = 0;
``` |
||

2306 | de6d9b64 | Fabrice Bellard | ```
} else {
``` |

2307 | 239c2f4c | Fabrice Bellard | if (decode_header(s, header) == 1) { |

2308 | ```
/* free format: compute frame size */
``` |
||

2309 | 2d83f323 | Zdenek Kabelac | ```
s->frame_size = -1;
``` |

2310 | memcpy(s->inbuf, s->inbuf + 1, s->inbuf_ptr - s->inbuf - 1); |
||

2311 | de5123dc | Zdenek Kabelac | s->inbuf_ptr--; |

2312 | 239c2f4c | Fabrice Bellard | ```
} else {
``` |

2313 | ```
/* update codec info */
``` |
||

2314 | avctx->sample_rate = s->sample_rate; |
||

2315 | avctx->channels = s->nb_channels; |
||

2316 | 2d83f323 | Zdenek Kabelac | avctx->bit_rate = s->bit_rate; |

2317 | 239c2f4c | Fabrice Bellard | } |

2318 | de6d9b64 | Fabrice Bellard | } |

2319 | } |
||

2320 | 239c2f4c | Fabrice Bellard | } else if (s->frame_size == -1) { |

2321 | ```
/* free format : find next sync to compute frame size */
``` |
||

2322 | len = MPA_MAX_CODED_FRAME_SIZE - len; |
||

2323 | ```
if (len > buf_size)
``` |
||

2324 | len = buf_size; |
||

2325 | if (len == 0) { |
||

2326 | ```
/* frame too long: resync */
``` |
||

2327 | ```
s->frame_size = 0;
``` |
||

2328 | ```
} else {
``` |
||

2329 | UINT8 *p, *pend; |
||

2330 | UINT32 header1; |
||

2331 | ```
int padding;
``` |
||

2332 | |||

2333 | memcpy(s->inbuf_ptr, buf_ptr, len); |
||

2334 | ```
/* check for header */
``` |
||

2335 | ```
p = s->inbuf_ptr - 3;
``` |
||

2336 | ```
pend = s->inbuf_ptr + len - 4;
``` |
||

2337 | ```
while (p <= pend) {
``` |
||

2338 | header = (p[0] << 24) | (p[1] << 16) | |
||

2339 | (p[2] << 8) | p[3]; |
||

2340 | header1 = (s->inbuf[0] << 24) | (s->inbuf[1] << 16) | |
||

2341 | (s->inbuf[2] << 8) | s->inbuf[3]; |
||

2342 | ```
/* check with high probability that we have a
``` |
||

2343 | ```
valid header */
``` |
||

2344 | ```
if ((header & SAME_HEADER_MASK) ==
``` |
||

2345 | (header1 & SAME_HEADER_MASK)) { |
||

2346 | ```
/* header found: update pointers */
``` |
||

2347 | ```
len = (p + 4) - s->inbuf_ptr;
``` |
||

2348 | buf_ptr += len; |
||

2349 | buf_size -= len; |
||

2350 | s->inbuf_ptr = p; |
||

2351 | ```
/* compute frame size */
``` |
||

2352 | s->free_format_next_header = header; |
||

2353 | s->free_format_frame_size = s->inbuf_ptr - s->inbuf; |
||

2354 | padding = (header1 >> 9) & 1; |
||

2355 | if (s->layer == 1) |
||

2356 | ```
s->free_format_frame_size -= padding * 4;
``` |
||

2357 | ```
else
``` |
||

2358 | s->free_format_frame_size -= padding; |
||

2359 | ```
dprintf("free frame size=%d padding=%d\n",
``` |
||

2360 | s->free_format_frame_size, padding); |
||

2361 | decode_header(s, header1); |
||

2362 | ```
goto next_data;
``` |
||

2363 | } |
||

2364 | p++; |
||

2365 | } |
||

2366 | ```
/* not found: simply increase pointers */
``` |
||

2367 | buf_ptr += len; |
||

2368 | s->inbuf_ptr += len; |
||

2369 | buf_size -= len; |
||

2370 | } |
||

2371 | de6d9b64 | Fabrice Bellard | } else if (len < s->frame_size) { |

2372 | de5123dc | Zdenek Kabelac | ```
if (s->frame_size > MPA_MAX_CODED_FRAME_SIZE)
``` |

2373 | s->frame_size = MPA_MAX_CODED_FRAME_SIZE; |
||

2374 | de6d9b64 | Fabrice Bellard | len = s->frame_size - len; |

2375 | ```
if (len > buf_size)
``` |
||

2376 | len = buf_size; |
||

2377 | 2d83f323 | Zdenek Kabelac | else if (len < 4) |

2378 | len = buf_size > 4 ? 4 : buf_size; |
||

2379 | de6d9b64 | Fabrice Bellard | memcpy(s->inbuf_ptr, buf_ptr, len); |

2380 | buf_ptr += len; |
||

2381 | s->inbuf_ptr += len; |
||

2382 | buf_size -= len; |
||

2383 | ```
} else {
``` |
||

2384 | out_size = mp_decode_frame(s, out_samples); |
||

2385 | s->inbuf_ptr = s->inbuf; |
||

2386 | ```
s->frame_size = 0;
``` |
||

2387 | *data_size = out_size; |
||

2388 | ```
break;
``` |
||

2389 | } |
||

2390 | 239c2f4c | Fabrice Bellard | ```
next_data:
``` |

2391 | de6d9b64 | Fabrice Bellard | } |

2392 | ```
return buf_ptr - buf;
``` |
||

2393 | } |
||

2394 | |||

2395 | AVCodec mp3_decoder = |
||

2396 | { |
||

2397 | ```
"mpegaudio",
``` |
||

2398 | CODEC_TYPE_AUDIO, |
||

2399 | CODEC_ID_MP2, |
||

2400 | ```
sizeof(MPADecodeContext),
``` |
||

2401 | decode_init, |
||

2402 | ```
NULL,
``` |
||

2403 | ```
NULL,
``` |
||

2404 | decode_frame, |
||

2405 | }; |