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


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* MPEG Audio decoder

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* Copyright (c) 2001 Gerard Lantau.

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*

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

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

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

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* (at your option) any later version.

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*

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* This program is distributed in the hope that it will be useful,

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

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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

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* GNU General Public License for more details.

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*

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

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

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

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*/

19 
//#define DEBUG

20 
#include "avcodec.h" 
21 
#include <math.h> 
22 
#include "mpegaudio.h" 
23  
24 
/*

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* TODO:

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

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*  test lsf / mpeg25 extensively.

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*/

29  
30 
/* 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 */ 
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#define WFRAC_BITS 16 /* fractional bits for window */ 
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#else

38 
#define FRAC_BITS 15 /* fractional bits for sb_samples and dct */ 
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#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)) 
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/* WARNING: only correct for posititive numbers */

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#define FIXR(a) ((int)((a) * FRAC_ONE + 0.5)) 
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#define FRAC_RND(a) (((a) + (FRAC_ONE/2)) >> FRAC_BITS) 
50  
51 
#if FRAC_BITS <= 15 
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typedef INT16 MPA_INT;

53 
#else

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typedef INT32 MPA_INT;

55 
#endif

56  
57 
/****************/

58  
59 
#define HEADER_SIZE 4 
60 
#define BACKSTEP_SIZE 512 
61  
62 
typedef struct MPADecodeContext { 
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UINT8 inbuf1[2][MPA_MAX_CODED_FRAME_SIZE + BACKSTEP_SIZE]; /* input buffer */ 
64 
int inbuf_index;

65 
UINT8 *inbuf_ptr, *inbuf; 
66 
int frame_size;

67 
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 
int error_protection;

72 
int layer;

73 
int sample_rate;

74 
int sample_rate_index; /* between 0 and 8 */ 
75 
int bit_rate;

76 
int old_frame_size;

77 
GetBitContext gb; 
78 
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];

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

87 
int frame_count;

88 
#endif

89 
} MPADecodeContext; 
90  
91 
/* 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 */ 
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UINT8 scale_factors[40];

108 
INT32 sb_hybrid[SBLIMIT * 18]; /* 576 samples */ 
109 
} GranuleDef; 
110  
111 
#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 
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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  
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#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] = { 
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SCALE_GEN(1.0 / 3.0), /* 3 steps */ 
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SCALE_GEN(1.0 / 5.0), /* 5 steps */ 
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SCALE_GEN(1.0 / 9.0), /* 9 steps */ 
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}; 
157  
158 
/* 2^(n/4) */

159 
static UINT32 scale_factor_mult3[4] = { 
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FIXR(1.0), 
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FIXR(1.18920711500272106671), 
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FIXR(1.41421356237309504880), 
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FIXR(1.68179283050742908605), 
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}; 
165  
166 
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[n1][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 
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m = (m * scale_factor_mult3[exponent & 3]);

215 
m = (m + (1 << (e1))) >> e; 
216 
return m;

217 
#else

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

219 
m = (m + (UINT64_C(1) << (e1))) >> e; 
220 
return m;

221 
#endif

222 
} 
223  
224  
225 
static int decode_init(AVCodecContext * avctx) 
226 
{ 
227 
MPADecodeContext *s = avctx>priv_data; 
228 
static int init; 
229 
int i, j, k;

230  
231 
if(!init) {

232 
/* 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, 
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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 
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 
#ifdef DEBUG

423 
s>frame_count = 0;

424 
#endif

425 
return 0; 
426 
} 
427  
428 
/* 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; /* 015 */ 
742 
SUM8(0, +=);

743 
p = synth_buf + 48  j; /* 3247 */ 
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; /* 1731 */ 
758 
SUM8(0, =);

759 
p = synth_buf + 16 + j; /* 4963 */ 
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[i1];

877 
for(i=17;i>=3;i=2) 
878 
in[i] += in[i2];

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 
/* 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 
/* bit rate */

957 
if (((header >> 12) & 0xf) == 0xf) 
958 
return 1; 
959 
/* frequency */

960 
if (((header >> 10) & 3) == 3) 
961 
return 1; 
962 
return 0; 
963 
} 
964  
965 
/* header + layer + bitrate + freq + lsf/mpeg25 */

966 
#define SAME_HEADER_MASK \

967 
(0xffe00000  (3 << 17)  (0xf << 12)  (3 << 10)  (3 << 19)) 
968  
969 
/* header decoding. MUST check the header before because no

970 
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 
{ 
974 
int sample_rate, frame_size, mpeg25, padding;

975 
int sample_rate_index, bitrate_index;

976 
if (header & (1<<20)) { 
977 
s>lsf = (header & (1<<19)) ? 0 : 1; 
978 
mpeg25 = 0;

979 
} else {

980 
s>lsf = 1;

981 
mpeg25 = 1;

982 
} 
983 

984 
s>layer = 4  ((header >> 17) & 3); 
985 
/* extract frequency */

986 
sample_rate_index = (header >> 10) & 3; 
987 
sample_rate = mpa_freq_tab[sample_rate_index] >> (s>lsf + mpeg25); 
988 
if (sample_rate == 0) 
989 
return 1; 
990 
sample_rate_index += 3 * (s>lsf + mpeg25);

991 
s>sample_rate_index = sample_rate_index; 
992 
s>error_protection = ((header >> 16) & 1) ^ 1; 
993  
994 
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  
1003 
if (s>mode == MPA_MONO)

1004 
s>nb_channels = 1;

1005 
else

1006 
s>nb_channels = 2;

1007 

1008 
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 
} 
1050 
s>sample_rate = sample_rate; 
1051 

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 
#endif

1068 
return 0; 
1069 
} 
1070  
1071 
/* return the number of decoded frames */

1072 
static int mp_decode_layer1(MPADecodeContext *s) 
1073 
{ 
1074 
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 

1107 
/* 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 

1143 
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  
1160 
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  
1170 
/* 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 
} 
1198  
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 
} 
1365  
1366 
/*

1367 
* Seek back in the stream for backstep bytes (at most 511 bytes)

1368 
*/

1369 
static void seek_to_maindata(MPADecodeContext *s, long backstep) 
1370 
{ 
1371 
UINT8 *ptr; 
1372  
1373 
/* compute current position in stream */

1374 
#ifdef ALT_BITSTREAM_READER

1375 
ptr = s>gb.buffer + (s>gb.index>>3);

1376 
#else

1377 
ptr = s>gb.buf_ptr  (s>gb.bit_cnt >> 3);

1378 
#endif

1379 
/* copy old data before current one */

1380 
ptr = backstep; 
1381 
memcpy(ptr, s>inbuf1[s>inbuf_index ^ 1] +

1382 
BACKSTEP_SIZE + s>old_frame_size  backstep, backstep); 
1383 
/* init get bits again */

1384 
init_get_bits(&s>gb, ptr, s>frame_size + backstep); 
1385  
1386 
/* 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 
#ifdef ALT_BITSTREAM_READER

1536 
s>gb.buffer = last_buf_ptr; 
1537 
s>gb.index = last_bit_cnt; 
1538 
#else

1539 
s>gb.buf_ptr = last_buf_ptr; 
1540 
s>gb.bit_buf = last_bit_buf; 
1541 
s>gb.bit_cnt = last_bit_cnt; 
1542 
#endif

1543 
} 
1544 
break;

1545 
} 
1546 
#ifdef ALT_BITSTREAM_READER

1547 
last_buf_ptr = s>gb.buffer; 
1548 
last_bit_cnt = s>gb.index; 
1549 
#else

1550 
last_buf_ptr = s>gb.buf_ptr; 
1551 
last_bit_buf = s>gb.bit_buf; 
1552 
last_bit_cnt = s>gb.bit_cnt; 
1553 
#endif

1554 

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 
return 0; 
1575 
} 
1576  
1577 
/* 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 istereo */

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 istereo */

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 
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 
/* 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 
len = HEADER_SIZE  len; 
2285 
if (len > buf_size)

2286 
len = buf_size; 
2287 
if (len > 0) { 
2288 
memcpy(s>inbuf_ptr, buf_ptr, len); 
2289 
buf_ptr += len; 
2290 
buf_size = len; 
2291 
s>inbuf_ptr += len; 
2292 
} 
2293 
if ((s>inbuf_ptr  s>inbuf) >= HEADER_SIZE) {

2294 
got_header:

2295 
header = (s>inbuf[0] << 24)  (s>inbuf[1] << 16)  
2296 
(s>inbuf[2] << 8)  s>inbuf[3]; 
2297  
2298 
if (check_header(header) < 0) { 
2299 
/* no sync found : move by one byte (inefficient, but simple!) */

2300 
memcpy(s>inbuf, s>inbuf + 1, s>inbuf_ptr  s>inbuf  1); 
2301 
s>inbuf_ptr; 
2302 
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 
} else {

2307 
if (decode_header(s, header) == 1) { 
2308 
/* free format: compute frame size */

2309 
s>frame_size = 1;

2310 
memcpy(s>inbuf, s>inbuf + 1, s>inbuf_ptr  s>inbuf  1); 
2311 
s>inbuf_ptr; 
2312 
} else {

2313 
/* update codec info */

2314 
avctx>sample_rate = s>sample_rate; 
2315 
avctx>channels = s>nb_channels; 
2316 
avctx>bit_rate = s>bit_rate; 
2317 
} 
2318 
} 
2319 
} 
2320 
} 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 
} else if (len < s>frame_size) { 
2372 
if (s>frame_size > MPA_MAX_CODED_FRAME_SIZE)

2373 
s>frame_size = MPA_MAX_CODED_FRAME_SIZE; 
2374 
len = s>frame_size  len; 
2375 
if (len > buf_size)

2376 
len = buf_size; 
2377 
else if (len < 4) 
2378 
len = buf_size > 4 ? 4 : buf_size; 
2379 
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 
next_data:

2391 
} 
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 
}; 