ffmpeg / libavcodec / ac3enc.c @ e62ef8f2
History  View  Annotate  Download (59.5 KB)
1 
/*


2 
* The simplest AC3 encoder

3 
* Copyright (c) 2000 Fabrice Bellard

4 
* Copyright (c) 20062010 Justin Ruggles <justin.ruggles@gmail.com>

5 
* Copyright (c) 20062010 Prakash Punnoor <prakash@punnoor.de>

6 
*

7 
* This file is part of FFmpeg.

8 
*

9 
* FFmpeg is free software; you can redistribute it and/or

10 
* modify it under the terms of the GNU Lesser General Public

11 
* License as published by the Free Software Foundation; either

12 
* version 2.1 of the License, or (at your option) any later version.

13 
*

14 
* FFmpeg is distributed in the hope that it will be useful,

15 
* but WITHOUT ANY WARRANTY; without even the implied warranty of

16 
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU

17 
* Lesser General Public License for more details.

18 
*

19 
* You should have received a copy of the GNU Lesser General Public

20 
* License along with FFmpeg; if not, write to the Free Software

21 
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 021101301 USA

22 
*/

23  
24 
/**

25 
* @file

26 
* The simplest AC3 encoder.

27 
*/

28  
29 
//#define DEBUG

30  
31 
#include "libavcore/audioconvert.h" 
32 
#include "libavutil/crc.h" 
33 
#include "avcodec.h" 
34 
#include "put_bits.h" 
35 
#include "dsputil.h" 
36 
#include "ac3.h" 
37 
#include "audioconvert.h" 
38  
39  
40 
/** Maximum number of exponent groups. +1 for separate DC exponent. */

41 
#define AC3_MAX_EXP_GROUPS 85 
42  
43 
/** Scale a float value by 2^bits and convert to an integer. */

44 
#define SCALE_FLOAT(a, bits) lrintf((a) * (float)(1 << (bits))) 
45  
46 
/** Scale a float value by 2^15, convert to an integer, and clip to int16_t range. */

47 
#define FIX15(a) av_clip_int16(SCALE_FLOAT(a, 15)) 
48  
49  
50 
/**

51 
* Compex number.

52 
* Used in fixedpoint MDCT calculation.

53 
*/

54 
typedef struct IComplex { 
55 
int16_t re,im; 
56 
} IComplex; 
57  
58 
typedef struct AC3MDCTContext { 
59 
AVCodecContext *avctx; ///< parent context for av_log()

60 
int nbits; ///< log2(transform size) 
61 
int16_t *costab; ///< FFT cos table

62 
int16_t *sintab; ///< FFT sin table

63 
int16_t *xcos1; ///< MDCT cos table

64 
int16_t *xsin1; ///< MDCT sin table

65 
int16_t *rot_tmp; ///< temp buffer for prerotated samples

66 
IComplex *cplx_tmp; ///< temp buffer for complex prerotated samples

67 
} AC3MDCTContext; 
68  
69 
/**

70 
* Data for a single audio block.

71 
*/

72 
typedef struct AC3Block { 
73 
uint8_t **bap; ///< bit allocation pointers (bap)

74 
int32_t **mdct_coef; ///< MDCT coefficients

75 
uint8_t **exp; ///< original exponents

76 
uint8_t **grouped_exp; ///< grouped exponents

77 
int16_t **psd; ///< psd per frequency bin

78 
int16_t **band_psd; ///< psd per critical band

79 
int16_t **mask; ///< masking curve

80 
uint16_t **qmant; ///< quantized mantissas

81 
uint8_t exp_strategy[AC3_MAX_CHANNELS]; ///< exponent strategies

82 
int8_t exp_shift[AC3_MAX_CHANNELS]; ///< exponent shift values

83 
} AC3Block; 
84  
85 
/**

86 
* AC3 encoder private context.

87 
*/

88 
typedef struct AC3EncodeContext { 
89 
PutBitContext pb; ///< bitstream writer context

90 
DSPContext dsp; 
91 
AC3MDCTContext mdct; ///< MDCT context

92  
93 
AC3Block blocks[AC3_MAX_BLOCKS]; ///< perblock info

94  
95 
int bitstream_id; ///< bitstream id (bsid) 
96 
int bitstream_mode; ///< bitstream mode (bsmod) 
97  
98 
int bit_rate; ///< target bit rate, in bitspersecond 
99 
int sample_rate; ///< sampling frequency, in Hz 
100  
101 
int frame_size_min; ///< minimum frame size in case rounding is necessary 
102 
int frame_size; ///< current frame size in bytes 
103 
int frame_size_code; ///< frame size code (frmsizecod) 
104 
int bits_written; ///< bit count (used to avg. bitrate) 
105 
int samples_written; ///< sample count (used to avg. bitrate) 
106  
107 
int fbw_channels; ///< number of fullbandwidth channels (nfchans) 
108 
int channels; ///< total number of channels (nchans) 
109 
int lfe_on; ///< indicates if there is an LFE channel (lfeon) 
110 
int lfe_channel; ///< channel index of the LFE channel 
111 
int channel_mode; ///< channel mode (acmod) 
112 
const uint8_t *channel_map; ///< channel map used to reorder channels 
113  
114 
int cutoff; ///< userspecified cutoff frequency, in Hz 
115 
int bandwidth_code[AC3_MAX_CHANNELS]; ///< bandwidth code (0 to 60) (chbwcod) 
116 
int nb_coefs[AC3_MAX_CHANNELS];

117  
118 
/* bitrate allocation control */

119 
int slow_gain_code; ///< slow gain code (sgaincod) 
120 
int slow_decay_code; ///< slow decay code (sdcycod) 
121 
int fast_decay_code; ///< fast decay code (fdcycod) 
122 
int db_per_bit_code; ///< dB/bit code (dbpbcod) 
123 
int floor_code; ///< floor code (floorcod) 
124 
AC3BitAllocParameters bit_alloc; ///< bit allocation parameters

125 
int coarse_snr_offset; ///< coarse SNR offsets (csnroffst) 
126 
int fast_gain_code[AC3_MAX_CHANNELS]; ///< fast gain codes (signaltomask ratio) (fgaincod) 
127 
int fine_snr_offset[AC3_MAX_CHANNELS]; ///< fine SNR offsets (fsnroffst) 
128 
int frame_bits_fixed; ///< number of noncoefficient bits for fixed parameters 
129 
int frame_bits; ///< all frame bits except exponents and mantissas 
130 
int exponent_bits; ///< number of bits used for exponents 
131  
132 
/* mantissa encoding */

133 
int mant1_cnt, mant2_cnt, mant4_cnt; ///< mantissa counts for bap=1,2,4 
134 
uint16_t *qmant1_ptr, *qmant2_ptr, *qmant4_ptr; ///< mantissa pointers for bap=1,2,4

135  
136 
int16_t **planar_samples; 
137 
uint8_t *bap_buffer; 
138 
uint8_t *bap1_buffer; 
139 
int32_t *mdct_coef_buffer; 
140 
uint8_t *exp_buffer; 
141 
uint8_t *grouped_exp_buffer; 
142 
int16_t *psd_buffer; 
143 
int16_t *band_psd_buffer; 
144 
int16_t *mask_buffer; 
145 
uint16_t *qmant_buffer; 
146  
147 
DECLARE_ALIGNED(16, int16_t, windowed_samples)[AC3_WINDOW_SIZE];

148 
} AC3EncodeContext; 
149  
150  
151 
/**

152 
* LUT for number of exponent groups.

153 
* exponent_group_tab[exponent strategy1][number of coefficients]

154 
*/

155 
uint8_t exponent_group_tab[3][256]; 
156  
157  
158 
/**

159 
* Adjust the frame size to make the average bit rate match the target bit rate.

160 
* This is only needed for 11025, 22050, and 44100 sample rates.

161 
*/

162 
static void adjust_frame_size(AC3EncodeContext *s) 
163 
{ 
164 
while (s>bits_written >= s>bit_rate && s>samples_written >= s>sample_rate) {

165 
s>bits_written = s>bit_rate; 
166 
s>samples_written = s>sample_rate; 
167 
} 
168 
s>frame_size = s>frame_size_min + 
169 
2 * (s>bits_written * s>sample_rate < s>samples_written * s>bit_rate);

170 
s>bits_written += s>frame_size * 8;

171 
s>samples_written += AC3_FRAME_SIZE; 
172 
} 
173  
174  
175 
/**

176 
* Deinterleave input samples.

177 
* Channels are reordered from FFmpeg's default order to AC3 order.

178 
*/

179 
static void deinterleave_input_samples(AC3EncodeContext *s, 
180 
const int16_t *samples)

181 
{ 
182 
int ch, i;

183  
184 
/* deinterleave and remap input samples */

185 
for (ch = 0; ch < s>channels; ch++) { 
186 
const int16_t *sptr;

187 
int sinc;

188  
189 
/* copy last 256 samples of previous frame to the start of the current frame */

190 
memcpy(&s>planar_samples[ch][0], &s>planar_samples[ch][AC3_FRAME_SIZE],

191 
AC3_BLOCK_SIZE * sizeof(s>planar_samples[0][0])); 
192  
193 
/* deinterleave */

194 
sinc = s>channels; 
195 
sptr = samples + s>channel_map[ch]; 
196 
for (i = AC3_BLOCK_SIZE; i < AC3_FRAME_SIZE+AC3_BLOCK_SIZE; i++) {

197 
s>planar_samples[ch][i] = *sptr; 
198 
sptr += sinc; 
199 
} 
200 
} 
201 
} 
202  
203  
204 
/**

205 
* Finalize MDCT and free allocated memory.

206 
*/

207 
static av_cold void mdct_end(AC3MDCTContext *mdct) 
208 
{ 
209 
mdct>nbits = 0;

210 
av_freep(&mdct>costab); 
211 
av_freep(&mdct>sintab); 
212 
av_freep(&mdct>xcos1); 
213 
av_freep(&mdct>xsin1); 
214 
av_freep(&mdct>rot_tmp); 
215 
av_freep(&mdct>cplx_tmp); 
216 
} 
217  
218  
219  
220 
/**

221 
* Initialize FFT tables.

222 
* @param ln log2(FFT size)

223 
*/

224 
static av_cold int fft_init(AC3MDCTContext *mdct, int ln) 
225 
{ 
226 
int i, n, n2;

227 
float alpha;

228  
229 
n = 1 << ln;

230 
n2 = n >> 1;

231  
232 
FF_ALLOC_OR_GOTO(mdct>avctx, mdct>costab, n2 * sizeof(*mdct>costab),

233 
fft_alloc_fail); 
234 
FF_ALLOC_OR_GOTO(mdct>avctx, mdct>sintab, n2 * sizeof(*mdct>sintab),

235 
fft_alloc_fail); 
236  
237 
for (i = 0; i < n2; i++) { 
238 
alpha = 2.0 * M_PI * i / n; 
239 
mdct>costab[i] = FIX15(cos(alpha)); 
240 
mdct>sintab[i] = FIX15(sin(alpha)); 
241 
} 
242  
243 
return 0; 
244 
fft_alloc_fail:

245 
mdct_end(mdct); 
246 
return AVERROR(ENOMEM);

247 
} 
248  
249  
250 
/**

251 
* Initialize MDCT tables.

252 
* @param nbits log2(MDCT size)

253 
*/

254 
static av_cold int mdct_init(AC3MDCTContext *mdct, int nbits) 
255 
{ 
256 
int i, n, n4, ret;

257  
258 
n = 1 << nbits;

259 
n4 = n >> 2;

260  
261 
mdct>nbits = nbits; 
262  
263 
ret = fft_init(mdct, nbits  2);

264 
if (ret)

265 
return ret;

266  
267 
FF_ALLOC_OR_GOTO(mdct>avctx, mdct>xcos1, n4 * sizeof(*mdct>xcos1),

268 
mdct_alloc_fail); 
269 
FF_ALLOC_OR_GOTO(mdct>avctx, mdct>xsin1 , n4 * sizeof(*mdct>xsin1),

270 
mdct_alloc_fail); 
271 
FF_ALLOC_OR_GOTO(mdct>avctx, mdct>rot_tmp, n * sizeof(*mdct>rot_tmp),

272 
mdct_alloc_fail); 
273 
FF_ALLOC_OR_GOTO(mdct>avctx, mdct>cplx_tmp, n4 * sizeof(*mdct>cplx_tmp),

274 
mdct_alloc_fail); 
275  
276 
for (i = 0; i < n4; i++) { 
277 
float alpha = 2.0 * M_PI * (i + 1.0 / 8.0) / n; 
278 
mdct>xcos1[i] = FIX15(cos(alpha)); 
279 
mdct>xsin1[i] = FIX15(sin(alpha)); 
280 
} 
281  
282 
return 0; 
283 
mdct_alloc_fail:

284 
mdct_end(mdct); 
285 
return AVERROR(ENOMEM);

286 
} 
287  
288  
289 
/** Butterfly op */

290 
#define BF(pre, pim, qre, qim, pre1, pim1, qre1, qim1) \

291 
{ \ 
292 
int ax, ay, bx, by; \

293 
bx = pre1; \ 
294 
by = pim1; \ 
295 
ax = qre1; \ 
296 
ay = qim1; \ 
297 
pre = (bx + ax) >> 1; \

298 
pim = (by + ay) >> 1; \

299 
qre = (bx  ax) >> 1; \

300 
qim = (by  ay) >> 1; \

301 
} 
302  
303  
304 
/** Complex multiply */

305 
#define CMUL(pre, pim, are, aim, bre, bim) \

306 
{ \ 
307 
pre = (MUL16(are, bre)  MUL16(aim, bim)) >> 15; \

308 
pim = (MUL16(are, bim) + MUL16(bre, aim)) >> 15; \

309 
} 
310  
311  
312 
/**

313 
* Calculate a 2^n point complex FFT on 2^ln points.

314 
* @param z complex input/output samples

315 
* @param ln log2(FFT size)

316 
*/

317 
static void fft(AC3MDCTContext *mdct, IComplex *z, int ln) 
318 
{ 
319 
int j, l, np, np2;

320 
int nblocks, nloops;

321 
register IComplex *p,*q;

322 
int tmp_re, tmp_im;

323  
324 
np = 1 << ln;

325  
326 
/* reverse */

327 
for (j = 0; j < np; j++) { 
328 
int k = av_reverse[j] >> (8  ln); 
329 
if (k < j)

330 
FFSWAP(IComplex, z[k], z[j]); 
331 
} 
332  
333 
/* pass 0 */

334  
335 
p = &z[0];

336 
j = np >> 1;

337 
do {

338 
BF(p[0].re, p[0].im, p[1].re, p[1].im, 
339 
p[0].re, p[0].im, p[1].re, p[1].im); 
340 
p += 2;

341 
} while (j);

342  
343 
/* pass 1 */

344  
345 
p = &z[0];

346 
j = np >> 2;

347 
do {

348 
BF(p[0].re, p[0].im, p[2].re, p[2].im, 
349 
p[0].re, p[0].im, p[2].re, p[2].im); 
350 
BF(p[1].re, p[1].im, p[3].re, p[3].im, 
351 
p[1].re, p[1].im, p[3].im, p[3].re); 
352 
p+=4;

353 
} while (j);

354  
355 
/* pass 2 .. ln1 */

356  
357 
nblocks = np >> 3;

358 
nloops = 1 << 2; 
359 
np2 = np >> 1;

360 
do {

361 
p = z; 
362 
q = z + nloops; 
363 
for (j = 0; j < nblocks; j++) { 
364 
BF(p>re, p>im, q>re, q>im, 
365 
p>re, p>im, q>re, q>im); 
366 
p++; 
367 
q++; 
368 
for(l = nblocks; l < np2; l += nblocks) {

369 
CMUL(tmp_re, tmp_im, mdct>costab[l], mdct>sintab[l], q>re, q>im); 
370 
BF(p>re, p>im, q>re, q>im, 
371 
p>re, p>im, tmp_re, tmp_im); 
372 
p++; 
373 
q++; 
374 
} 
375 
p += nloops; 
376 
q += nloops; 
377 
} 
378 
nblocks = nblocks >> 1;

379 
nloops = nloops << 1;

380 
} while (nblocks);

381 
} 
382  
383  
384 
/**

385 
* Calculate a 512point MDCT

386 
* @param out 256 output frequency coefficients

387 
* @param in 512 windowed input audio samples

388 
*/

389 
static void mdct512(AC3MDCTContext *mdct, int32_t *out, int16_t *in) 
390 
{ 
391 
int i, re, im, n, n2, n4;

392 
int16_t *rot = mdct>rot_tmp; 
393 
IComplex *x = mdct>cplx_tmp; 
394  
395 
n = 1 << mdct>nbits;

396 
n2 = n >> 1;

397 
n4 = n >> 2;

398  
399 
/* shift to simplify computations */

400 
for (i = 0; i <n4; i++) 
401 
rot[i] = in[i + 3*n4];

402 
memcpy(&rot[n4], &in[0], 3*n4*sizeof(*in)); 
403  
404 
/* pre rotation */

405 
for (i = 0; i < n4; i++) { 
406 
re = ((int)rot[ 2*i]  (int)rot[ n12*i]) >> 1; 
407 
im = ((int)rot[n2+2*i]  (int)rot[n212*i]) >> 1; 
408 
CMUL(x[i].re, x[i].im, re, im, mdct>xcos1[i], mdct>xsin1[i]); 
409 
} 
410  
411 
fft(mdct, x, mdct>nbits  2);

412  
413 
/* post rotation */

414 
for (i = 0; i < n4; i++) { 
415 
re = x[i].re; 
416 
im = x[i].im; 
417 
CMUL(out[n212*i], out[2*i], re, im, mdct>xsin1[i], mdct>xcos1[i]); 
418 
} 
419 
} 
420  
421  
422 
/**

423 
* Apply KBD window to input samples prior to MDCT.

424 
*/

425 
static void apply_window(int16_t *output, const int16_t *input, 
426 
const int16_t *window, int n) 
427 
{ 
428 
int i;

429 
int n2 = n >> 1; 
430  
431 
for (i = 0; i < n2; i++) { 
432 
output[i] = MUL16(input[i], window[i]) >> 15;

433 
output[ni1] = MUL16(input[ni1], window[i]) >> 15; 
434 
} 
435 
} 
436  
437  
438 
/**

439 
* Calculate the log2() of the maximum absolute value in an array.

440 
* @param tab input array

441 
* @param n number of values in the array

442 
* @return log2(max(abs(tab[])))

443 
*/

444 
static int log2_tab(int16_t *tab, int n) 
445 
{ 
446 
int i, v;

447  
448 
v = 0;

449 
for (i = 0; i < n; i++) 
450 
v = abs(tab[i]); 
451  
452 
return av_log2(v);

453 
} 
454  
455  
456 
/**

457 
* Leftshift each value in an array by a specified amount.

458 
* @param tab input array

459 
* @param n number of values in the array

460 
* @param lshift left shift amount. a negative value means right shift.

461 
*/

462 
static void lshift_tab(int16_t *tab, int n, int lshift) 
463 
{ 
464 
int i;

465  
466 
if (lshift > 0) { 
467 
for (i = 0; i < n; i++) 
468 
tab[i] <<= lshift; 
469 
} else if (lshift < 0) { 
470 
lshift = lshift; 
471 
for (i = 0; i < n; i++) 
472 
tab[i] >>= lshift; 
473 
} 
474 
} 
475  
476  
477 
/**

478 
* Normalize the input samples to use the maximum available precision.

479 
* This assumes signed 16bit input samples. Exponents are reduced by 9 to

480 
* match the 24bit internal precision for MDCT coefficients.

481 
*

482 
* @return exponent shift

483 
*/

484 
static int normalize_samples(AC3EncodeContext *s) 
485 
{ 
486 
int v = 14  log2_tab(s>windowed_samples, AC3_WINDOW_SIZE); 
487 
v = FFMAX(0, v);

488 
lshift_tab(s>windowed_samples, AC3_WINDOW_SIZE, v); 
489 
return v  9; 
490 
} 
491  
492  
493 
/**

494 
* Apply the MDCT to input samples to generate frequency coefficients.

495 
* This applies the KBD window and normalizes the input to reduce precision

496 
* loss due to fixedpoint calculations.

497 
*/

498 
static void apply_mdct(AC3EncodeContext *s) 
499 
{ 
500 
int blk, ch;

501  
502 
for (ch = 0; ch < s>channels; ch++) { 
503 
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) { 
504 
AC3Block *block = &s>blocks[blk]; 
505 
const int16_t *input_samples = &s>planar_samples[ch][blk * AC3_BLOCK_SIZE];

506  
507 
apply_window(s>windowed_samples, input_samples, ff_ac3_window, AC3_WINDOW_SIZE); 
508  
509 
block>exp_shift[ch] = normalize_samples(s); 
510  
511 
mdct512(&s>mdct, block>mdct_coef[ch], s>windowed_samples); 
512 
} 
513 
} 
514 
} 
515  
516  
517 
/**

518 
* Initialize exponent tables.

519 
*/

520 
static av_cold void exponent_init(AC3EncodeContext *s) 
521 
{ 
522 
int i;

523 
for (i = 73; i < 256; i++) { 
524 
exponent_group_tab[0][i] = (i  1) / 3; 
525 
exponent_group_tab[1][i] = (i + 2) / 6; 
526 
exponent_group_tab[2][i] = (i + 8) / 12; 
527 
} 
528 
/* LFE */

529 
exponent_group_tab[0][7] = 2; 
530 
} 
531  
532  
533 
/**

534 
* Extract exponents from the MDCT coefficients.

535 
* This takes into account the normalization that was done to the input samples

536 
* by adjusting the exponents by the exponent shift values.

537 
*/

538 
static void extract_exponents(AC3EncodeContext *s) 
539 
{ 
540 
int blk, ch, i;

541  
542 
for (ch = 0; ch < s>channels; ch++) { 
543 
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) { 
544 
AC3Block *block = &s>blocks[blk]; 
545 
for (i = 0; i < AC3_MAX_COEFS; i++) { 
546 
int e;

547 
int v = abs(block>mdct_coef[ch][i]);

548 
if (v == 0) 
549 
e = 24;

550 
else {

551 
e = 23  av_log2(v) + block>exp_shift[ch];

552 
if (e >= 24) { 
553 
e = 24;

554 
block>mdct_coef[ch][i] = 0;

555 
} 
556 
} 
557 
block>exp[ch][i] = e; 
558 
} 
559 
} 
560 
} 
561 
} 
562  
563  
564 
/**

565 
* Exponent Difference Threshold.

566 
* New exponents are sent if their SAD exceed this number.

567 
*/

568 
#define EXP_DIFF_THRESHOLD 1000 
569  
570  
571 
/**

572 
* Calculate exponent strategies for all blocks in a single channel.

573 
*/

574 
static void compute_exp_strategy_ch(AC3EncodeContext *s, uint8_t *exp_strategy, uint8_t **exp) 
575 
{ 
576 
int blk, blk1;

577 
int exp_diff;

578  
579 
/* estimate if the exponent variation & decide if they should be

580 
reused in the next frame */

581 
exp_strategy[0] = EXP_NEW;

582 
for (blk = 1; blk < AC3_MAX_BLOCKS; blk++) { 
583 
exp_diff = s>dsp.sad[0](NULL, exp[blk], exp[blk1], 16, 16); 
584 
if (exp_diff > EXP_DIFF_THRESHOLD)

585 
exp_strategy[blk] = EXP_NEW; 
586 
else

587 
exp_strategy[blk] = EXP_REUSE; 
588 
} 
589  
590 
/* now select the encoding strategy type : if exponents are often

591 
recoded, we use a coarse encoding */

592 
blk = 0;

593 
while (blk < AC3_MAX_BLOCKS) {

594 
blk1 = blk + 1;

595 
while (blk1 < AC3_MAX_BLOCKS && exp_strategy[blk1] == EXP_REUSE)

596 
blk1++; 
597 
switch (blk1  blk) {

598 
case 1: exp_strategy[blk] = EXP_D45; break; 
599 
case 2: 
600 
case 3: exp_strategy[blk] = EXP_D25; break; 
601 
default: exp_strategy[blk] = EXP_D15; break; 
602 
} 
603 
blk = blk1; 
604 
} 
605 
} 
606  
607  
608 
/**

609 
* Calculate exponent strategies for all channels.

610 
* Array arrangement is reversed to simplify the perchannel calculation.

611 
*/

612 
static void compute_exp_strategy(AC3EncodeContext *s) 
613 
{ 
614 
uint8_t *exp1[AC3_MAX_CHANNELS][AC3_MAX_BLOCKS]; 
615 
uint8_t exp_str1[AC3_MAX_CHANNELS][AC3_MAX_BLOCKS]; 
616 
int ch, blk;

617  
618 
for (ch = 0; ch < s>fbw_channels; ch++) { 
619 
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) { 
620 
exp1[ch][blk] = s>blocks[blk].exp[ch]; 
621 
exp_str1[ch][blk] = s>blocks[blk].exp_strategy[ch]; 
622 
} 
623  
624 
compute_exp_strategy_ch(s, exp_str1[ch], exp1[ch]); 
625  
626 
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) 
627 
s>blocks[blk].exp_strategy[ch] = exp_str1[ch][blk]; 
628 
} 
629 
if (s>lfe_on) {

630 
ch = s>lfe_channel; 
631 
s>blocks[0].exp_strategy[ch] = EXP_D15;

632 
for (blk = 1; blk < AC3_MAX_BLOCKS; blk++) 
633 
s>blocks[blk].exp_strategy[ch] = EXP_REUSE; 
634 
} 
635 
} 
636  
637  
638 
/**

639 
* Set each encoded exponent in a block to the minimum of itself and the

640 
* exponent in the same frequency bin of a following block.

641 
* exp[i] = min(exp[i], exp1[i]

642 
*/

643 
static void exponent_min(uint8_t *exp, uint8_t *exp1, int n) 
644 
{ 
645 
int i;

646 
for (i = 0; i < n; i++) { 
647 
if (exp1[i] < exp[i])

648 
exp[i] = exp1[i]; 
649 
} 
650 
} 
651  
652  
653 
/**

654 
* Update the exponents so that they are the ones the decoder will decode.

655 
*/

656 
static void encode_exponents_blk_ch(uint8_t *exp, 
657 
int nb_exps, int exp_strategy) 
658 
{ 
659 
int nb_groups, i, k;

660  
661 
nb_groups = exponent_group_tab[exp_strategy1][nb_exps] * 3; 
662  
663 
/* for each group, compute the minimum exponent */

664 
switch(exp_strategy) {

665 
case EXP_D25:

666 
for (i = 1, k = 1; i <= nb_groups; i++) { 
667 
uint8_t exp_min = exp[k]; 
668 
if (exp[k+1] < exp_min) 
669 
exp_min = exp[k+1];

670 
exp[i] = exp_min; 
671 
k += 2;

672 
} 
673 
break;

674 
case EXP_D45:

675 
for (i = 1, k = 1; i <= nb_groups; i++) { 
676 
uint8_t exp_min = exp[k]; 
677 
if (exp[k+1] < exp_min) 
678 
exp_min = exp[k+1];

679 
if (exp[k+2] < exp_min) 
680 
exp_min = exp[k+2];

681 
if (exp[k+3] < exp_min) 
682 
exp_min = exp[k+3];

683 
exp[i] = exp_min; 
684 
k += 4;

685 
} 
686 
break;

687 
} 
688  
689 
/* constraint for DC exponent */

690 
if (exp[0] > 15) 
691 
exp[0] = 15; 
692  
693 
/* decrease the delta between each groups to within 2 so that they can be

694 
differentially encoded */

695 
for (i = 1; i <= nb_groups; i++) 
696 
exp[i] = FFMIN(exp[i], exp[i1] + 2); 
697 
i; 
698 
while (i >= 0) 
699 
exp[i] = FFMIN(exp[i], exp[i+1] + 2); 
700  
701 
/* now we have the exponent values the decoder will see */

702 
switch (exp_strategy) {

703 
case EXP_D25:

704 
for (i = nb_groups, k = nb_groups * 2; i > 0; i) { 
705 
uint8_t exp1 = exp[i]; 
706 
exp[k] = exp1; 
707 
exp[k] = exp1; 
708 
} 
709 
break;

710 
case EXP_D45:

711 
for (i = nb_groups, k = nb_groups * 4; i > 0; i) { 
712 
exp[k] = exp[k1] = exp[k2] = exp[k3] = exp[i]; 
713 
k = 4;

714 
} 
715 
break;

716 
} 
717 
} 
718  
719  
720 
/**

721 
* Encode exponents from original extracted form to what the decoder will see.

722 
* This copies and groups exponents based on exponent strategy and reduces

723 
* deltas between adjacent exponent groups so that they can be differentially

724 
* encoded.

725 
*/

726 
static void encode_exponents(AC3EncodeContext *s) 
727 
{ 
728 
int blk, blk1, blk2, ch;

729 
AC3Block *block, *block1, *block2; 
730  
731 
for (ch = 0; ch < s>channels; ch++) { 
732 
blk = 0;

733 
block = &s>blocks[0];

734 
while (blk < AC3_MAX_BLOCKS) {

735 
blk1 = blk + 1;

736 
block1 = block + 1;

737 
/* for the EXP_REUSE case we select the min of the exponents */

738 
while (blk1 < AC3_MAX_BLOCKS && block1>exp_strategy[ch] == EXP_REUSE) {

739 
exponent_min(block>exp[ch], block1>exp[ch], s>nb_coefs[ch]); 
740 
blk1++; 
741 
block1++; 
742 
} 
743 
encode_exponents_blk_ch(block>exp[ch], s>nb_coefs[ch], 
744 
block>exp_strategy[ch]); 
745 
/* copy encoded exponents for reuse case */

746 
block2 = block + 1;

747 
for (blk2 = blk+1; blk2 < blk1; blk2++, block2++) { 
748 
memcpy(block2>exp[ch], block>exp[ch], 
749 
s>nb_coefs[ch] * sizeof(uint8_t));

750 
} 
751 
blk = blk1; 
752 
block = block1; 
753 
} 
754 
} 
755 
} 
756  
757  
758 
/**

759 
* Group exponents.

760 
* 3 deltaencoded exponents are in each 7bit group. The number of groups

761 
* varies depending on exponent strategy and bandwidth.

762 
*/

763 
static void group_exponents(AC3EncodeContext *s) 
764 
{ 
765 
int blk, ch, i;

766 
int group_size, nb_groups, bit_count;

767 
uint8_t *p; 
768 
int delta0, delta1, delta2;

769 
int exp0, exp1;

770  
771 
bit_count = 0;

772 
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) { 
773 
AC3Block *block = &s>blocks[blk]; 
774 
for (ch = 0; ch < s>channels; ch++) { 
775 
if (block>exp_strategy[ch] == EXP_REUSE) {

776 
continue;

777 
} 
778 
group_size = block>exp_strategy[ch] + (block>exp_strategy[ch] == EXP_D45); 
779 
nb_groups = exponent_group_tab[block>exp_strategy[ch]1][s>nb_coefs[ch]];

780 
bit_count += 4 + (nb_groups * 7); 
781 
p = block>exp[ch]; 
782  
783 
/* DC exponent */

784 
exp1 = *p++; 
785 
block>grouped_exp[ch][0] = exp1;

786  
787 
/* remaining exponents are delta encoded */

788 
for (i = 1; i <= nb_groups; i++) { 
789 
/* merge three delta in one code */

790 
exp0 = exp1; 
791 
exp1 = p[0];

792 
p += group_size; 
793 
delta0 = exp1  exp0 + 2;

794  
795 
exp0 = exp1; 
796 
exp1 = p[0];

797 
p += group_size; 
798 
delta1 = exp1  exp0 + 2;

799  
800 
exp0 = exp1; 
801 
exp1 = p[0];

802 
p += group_size; 
803 
delta2 = exp1  exp0 + 2;

804  
805 
block>grouped_exp[ch][i] = ((delta0 * 5 + delta1) * 5) + delta2; 
806 
} 
807 
} 
808 
} 
809  
810 
s>exponent_bits = bit_count; 
811 
} 
812  
813  
814 
/**

815 
* Calculate final exponents from the supplied MDCT coefficients and exponent shift.

816 
* Extract exponents from MDCT coefficients, calculate exponent strategies,

817 
* and encode final exponents.

818 
*/

819 
static void process_exponents(AC3EncodeContext *s) 
820 
{ 
821 
extract_exponents(s); 
822  
823 
compute_exp_strategy(s); 
824  
825 
encode_exponents(s); 
826  
827 
group_exponents(s); 
828 
} 
829  
830  
831 
/**

832 
* Count frame bits that are based solely on fixed parameters.

833 
* This only has to be run once when the encoder is initialized.

834 
*/

835 
static void count_frame_bits_fixed(AC3EncodeContext *s) 
836 
{ 
837 
static const int frame_bits_inc[8] = { 0, 0, 2, 2, 2, 4, 2, 4 }; 
838 
int blk;

839 
int frame_bits;

840  
841 
/* assumptions:

842 
* no dynamic range codes

843 
* no channel coupling

844 
* no rematrixing

845 
* bit allocation parameters do not change between blocks

846 
* SNR offsets do not change between blocks

847 
* no delta bit allocation

848 
* no skipped data

849 
* no auxilliary data

850 
*/

851  
852 
/* header size */

853 
frame_bits = 65;

854 
frame_bits += frame_bits_inc[s>channel_mode]; 
855  
856 
/* audio blocks */

857 
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) { 
858 
frame_bits += s>fbw_channels * 2 + 2; /* blksw * c, dithflag * c, dynrnge, cplstre */ 
859 
if (s>channel_mode == AC3_CHMODE_STEREO) {

860 
frame_bits++; /* rematstr */

861 
if (!blk)

862 
frame_bits += 4;

863 
} 
864 
frame_bits += 2 * s>fbw_channels; /* chexpstr[2] * c */ 
865 
if (s>lfe_on)

866 
frame_bits++; /* lfeexpstr */

867 
frame_bits++; /* baie */

868 
frame_bits++; /* snr */

869 
frame_bits += 2; /* delta / skip */ 
870 
} 
871 
frame_bits++; /* cplinu for block 0 */

872 
/* bit alloc info */

873 
/* sdcycod[2], fdcycod[2], sgaincod[2], dbpbcod[2], floorcod[3] */

874 
/* csnroffset[6] */

875 
/* (fsnoffset[4] + fgaincod[4]) * c */

876 
frame_bits += 2*4 + 3 + 6 + s>channels * (4 + 3); 
877  
878 
/* auxdatae, crcrsv */

879 
frame_bits += 2;

880  
881 
/* CRC */

882 
frame_bits += 16;

883  
884 
s>frame_bits_fixed = frame_bits; 
885 
} 
886  
887  
888 
/**

889 
* Initialize bit allocation.

890 
* Set default parameter codes and calculate parameter values.

891 
*/

892 
static void bit_alloc_init(AC3EncodeContext *s) 
893 
{ 
894 
int ch;

895  
896 
/* init default parameters */

897 
s>slow_decay_code = 2;

898 
s>fast_decay_code = 1;

899 
s>slow_gain_code = 1;

900 
s>db_per_bit_code = 2;

901 
s>floor_code = 4;

902 
for (ch = 0; ch < s>channels; ch++) 
903 
s>fast_gain_code[ch] = 4;

904  
905 
/* initial snr offset */

906 
s>coarse_snr_offset = 40;

907  
908 
/* compute real values */

909 
/* currently none of these values change during encoding, so we can just

910 
set them once at initialization */

911 
s>bit_alloc.slow_decay = ff_ac3_slow_decay_tab[s>slow_decay_code] >> s>bit_alloc.sr_shift; 
912 
s>bit_alloc.fast_decay = ff_ac3_fast_decay_tab[s>fast_decay_code] >> s>bit_alloc.sr_shift; 
913 
s>bit_alloc.slow_gain = ff_ac3_slow_gain_tab[s>slow_gain_code]; 
914 
s>bit_alloc.db_per_bit = ff_ac3_db_per_bit_tab[s>db_per_bit_code]; 
915 
s>bit_alloc.floor = ff_ac3_floor_tab[s>floor_code]; 
916  
917 
count_frame_bits_fixed(s); 
918 
} 
919  
920  
921 
/**

922 
* Count the bits used to encode the frame, minus exponents and mantissas.

923 
* Bits based on fixed parameters have already been counted, so now we just

924 
* have to add the bits based on parameters that change during encoding.

925 
*/

926 
static void count_frame_bits(AC3EncodeContext *s) 
927 
{ 
928 
int blk, ch;

929 
int frame_bits = 0; 
930  
931 
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) { 
932 
uint8_t *exp_strategy = s>blocks[blk].exp_strategy; 
933 
for (ch = 0; ch < s>fbw_channels; ch++) { 
934 
if (exp_strategy[ch] != EXP_REUSE)

935 
frame_bits += 6 + 2; /* chbwcod[6], gainrng[2] */ 
936 
} 
937 
} 
938 
s>frame_bits = s>frame_bits_fixed + frame_bits; 
939 
} 
940  
941  
942 
/**

943 
* Calculate the number of bits needed to encode a set of mantissas.

944 
*/

945 
static int compute_mantissa_size(int mant_cnt[5], uint8_t *bap, int nb_coefs) 
946 
{ 
947 
int bits, b, i;

948  
949 
bits = 0;

950 
for (i = 0; i < nb_coefs; i++) { 
951 
b = bap[i]; 
952 
if (b <= 4) { 
953 
// bap=1 to bap=4 will be counted in compute_mantissa_size_final

954 
mant_cnt[b]++; 
955 
} else if (b <= 13) { 
956 
// bap=5 to bap=13 use (bap1) bits

957 
bits += b  1;

958 
} else {

959 
// bap=14 uses 14 bits and bap=15 uses 16 bits

960 
bits += (b == 14) ? 14 : 16; 
961 
} 
962 
} 
963 
return bits;

964 
} 
965  
966  
967 
/**

968 
* Finalize the mantissa bit count by adding in the grouped mantissas.

969 
*/

970 
static int compute_mantissa_size_final(int mant_cnt[5]) 
971 
{ 
972 
// bap=1 : 3 mantissas in 5 bits

973 
int bits = (mant_cnt[1] / 3) * 5; 
974 
// bap=2 : 3 mantissas in 7 bits

975 
// bap=4 : 2 mantissas in 7 bits

976 
bits += ((mant_cnt[2] / 3) + (mant_cnt[4] >> 1)) * 7; 
977 
// bap=3 : each mantissa is 3 bits

978 
bits += mant_cnt[3] * 3; 
979 
return bits;

980 
} 
981  
982  
983 
/**

984 
* Calculate masking curve based on the final exponents.

985 
* Also calculate the power spectral densities to use in future calculations.

986 
*/

987 
static void bit_alloc_masking(AC3EncodeContext *s) 
988 
{ 
989 
int blk, ch;

990  
991 
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) { 
992 
AC3Block *block = &s>blocks[blk]; 
993 
for (ch = 0; ch < s>channels; ch++) { 
994 
/* We only need psd and mask for calculating bap.

995 
Since we currently do not calculate bap when exponent

996 
strategy is EXP_REUSE we do not need to calculate psd or mask. */

997 
if (block>exp_strategy[ch] != EXP_REUSE) {

998 
ff_ac3_bit_alloc_calc_psd(block>exp[ch], 0,

999 
s>nb_coefs[ch], 
1000 
block>psd[ch], block>band_psd[ch]); 
1001 
ff_ac3_bit_alloc_calc_mask(&s>bit_alloc, block>band_psd[ch], 
1002 
0, s>nb_coefs[ch],

1003 
ff_ac3_fast_gain_tab[s>fast_gain_code[ch]], 
1004 
ch == s>lfe_channel, 
1005 
DBA_NONE, 0, NULL, NULL, NULL, 
1006 
block>mask[ch]); 
1007 
} 
1008 
} 
1009 
} 
1010 
} 
1011  
1012  
1013 
/**

1014 
* Ensure that bap for each block and channel point to the current bap_buffer.

1015 
* They may have been switched during the bit allocation search.

1016 
*/

1017 
static void reset_block_bap(AC3EncodeContext *s) 
1018 
{ 
1019 
int blk, ch;

1020 
if (s>blocks[0].bap[0] == s>bap_buffer) 
1021 
return;

1022 
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) { 
1023 
for (ch = 0; ch < s>channels; ch++) { 
1024 
s>blocks[blk].bap[ch] = &s>bap_buffer[AC3_MAX_COEFS * (blk * s>channels + ch)]; 
1025 
} 
1026 
} 
1027 
} 
1028  
1029  
1030 
/**

1031 
* Run the bit allocation with a given SNR offset.

1032 
* This calculates the bit allocation pointers that will be used to determine

1033 
* the quantization of each mantissa.

1034 
* @return the number of bits needed for mantissas if the given SNR offset is

1035 
* is used.

1036 
*/

1037 
static int bit_alloc(AC3EncodeContext *s, 
1038 
int snr_offset)

1039 
{ 
1040 
int blk, ch;

1041 
int mantissa_bits;

1042 
int mant_cnt[5]; 
1043  
1044 
snr_offset = (snr_offset  240) << 2; 
1045  
1046 
reset_block_bap(s); 
1047 
mantissa_bits = 0;

1048 
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) { 
1049 
AC3Block *block = &s>blocks[blk]; 
1050 
// initialize grouped mantissa counts. these are set so that they are

1051 
// padded to the next whole group size when bits are counted in

1052 
// compute_mantissa_size_final

1053 
mant_cnt[0] = mant_cnt[3] = 0; 
1054 
mant_cnt[1] = mant_cnt[2] = 2; 
1055 
mant_cnt[4] = 1; 
1056 
for (ch = 0; ch < s>channels; ch++) { 
1057 
/* Currently the only bit allocation parameters which vary across

1058 
blocks within a frame are the exponent values. We can take

1059 
advantage of that by reusing the bit allocation pointers

1060 
whenever we reuse exponents. */

1061 
if (block>exp_strategy[ch] == EXP_REUSE) {

1062 
memcpy(block>bap[ch], s>blocks[blk1].bap[ch], AC3_MAX_COEFS);

1063 
} else {

1064 
ff_ac3_bit_alloc_calc_bap(block>mask[ch], block>psd[ch], 0,

1065 
s>nb_coefs[ch], snr_offset, 
1066 
s>bit_alloc.floor, ff_ac3_bap_tab, 
1067 
block>bap[ch]); 
1068 
} 
1069 
mantissa_bits += compute_mantissa_size(mant_cnt, block>bap[ch], s>nb_coefs[ch]); 
1070 
} 
1071 
mantissa_bits += compute_mantissa_size_final(mant_cnt); 
1072 
} 
1073 
return mantissa_bits;

1074 
} 
1075  
1076  
1077 
/**

1078 
* Constant bitrate bit allocation search.

1079 
* Find the largest SNR offset that will allow data to fit in the frame.

1080 
*/

1081 
static int cbr_bit_allocation(AC3EncodeContext *s) 
1082 
{ 
1083 
int ch;

1084 
int bits_left;

1085 
int snr_offset, snr_incr;

1086  
1087 
bits_left = 8 * s>frame_size  (s>frame_bits + s>exponent_bits);

1088  
1089 
snr_offset = s>coarse_snr_offset << 4;

1090  
1091 
while (snr_offset >= 0 && 
1092 
bit_alloc(s, snr_offset) > bits_left) { 
1093 
snr_offset = 64;

1094 
} 
1095 
if (snr_offset < 0) 
1096 
return AVERROR(EINVAL);

1097  
1098 
FFSWAP(uint8_t *, s>bap_buffer, s>bap1_buffer); 
1099 
for (snr_incr = 64; snr_incr > 0; snr_incr >>= 2) { 
1100 
while (snr_offset + 64 <= 1023 && 
1101 
bit_alloc(s, snr_offset + snr_incr) <= bits_left) { 
1102 
snr_offset += snr_incr; 
1103 
FFSWAP(uint8_t *, s>bap_buffer, s>bap1_buffer); 
1104 
} 
1105 
} 
1106 
FFSWAP(uint8_t *, s>bap_buffer, s>bap1_buffer); 
1107 
reset_block_bap(s); 
1108  
1109 
s>coarse_snr_offset = snr_offset >> 4;

1110 
for (ch = 0; ch < s>channels; ch++) 
1111 
s>fine_snr_offset[ch] = snr_offset & 0xF;

1112  
1113 
return 0; 
1114 
} 
1115  
1116  
1117 
/**

1118 
* Perform bit allocation search.

1119 
* Finds the SNR offset value that maximizes quality and fits in the specified

1120 
* frame size. Output is the SNR offset and a set of bit allocation pointers

1121 
* used to quantize the mantissas.

1122 
*/

1123 
static int compute_bit_allocation(AC3EncodeContext *s) 
1124 
{ 
1125 
count_frame_bits(s); 
1126  
1127 
bit_alloc_masking(s); 
1128  
1129 
return cbr_bit_allocation(s);

1130 
} 
1131  
1132  
1133 
/**

1134 
* Symmetric quantization on 'levels' levels.

1135 
*/

1136 
static inline int sym_quant(int c, int e, int levels) 
1137 
{ 
1138 
int v;

1139  
1140 
if (c >= 0) { 
1141 
v = (levels * (c << e)) >> 24;

1142 
v = (v + 1) >> 1; 
1143 
v = (levels >> 1) + v;

1144 
} else {

1145 
v = (levels * ((c) << e)) >> 24;

1146 
v = (v + 1) >> 1; 
1147 
v = (levels >> 1)  v;

1148 
} 
1149 
assert(v >= 0 && v < levels);

1150 
return v;

1151 
} 
1152  
1153  
1154 
/**

1155 
* Asymmetric quantization on 2^qbits levels.

1156 
*/

1157 
static inline int asym_quant(int c, int e, int qbits) 
1158 
{ 
1159 
int lshift, m, v;

1160  
1161 
lshift = e + qbits  24;

1162 
if (lshift >= 0) 
1163 
v = c << lshift; 
1164 
else

1165 
v = c >> (lshift); 
1166 
/* rounding */

1167 
v = (v + 1) >> 1; 
1168 
m = (1 << (qbits1)); 
1169 
if (v >= m)

1170 
v = m  1;

1171 
assert(v >= m); 
1172 
return v & ((1 << qbits)1); 
1173 
} 
1174  
1175  
1176 
/**

1177 
* Quantize a set of mantissas for a single channel in a single block.

1178 
*/

1179 
static void quantize_mantissas_blk_ch(AC3EncodeContext *s, 
1180 
int32_t *mdct_coef, int8_t exp_shift, 
1181 
uint8_t *exp, uint8_t *bap, 
1182 
uint16_t *qmant, int n)

1183 
{ 
1184 
int i;

1185  
1186 
for (i = 0; i < n; i++) { 
1187 
int v;

1188 
int c = mdct_coef[i];

1189 
int e = exp[i]  exp_shift;

1190 
int b = bap[i];

1191 
switch (b) {

1192 
case 0: 
1193 
v = 0;

1194 
break;

1195 
case 1: 
1196 
v = sym_quant(c, e, 3);

1197 
switch (s>mant1_cnt) {

1198 
case 0: 
1199 
s>qmant1_ptr = &qmant[i]; 
1200 
v = 9 * v;

1201 
s>mant1_cnt = 1;

1202 
break;

1203 
case 1: 
1204 
*s>qmant1_ptr += 3 * v;

1205 
s>mant1_cnt = 2;

1206 
v = 128;

1207 
break;

1208 
default:

1209 
*s>qmant1_ptr += v; 
1210 
s>mant1_cnt = 0;

1211 
v = 128;

1212 
break;

1213 
} 
1214 
break;

1215 
case 2: 
1216 
v = sym_quant(c, e, 5);

1217 
switch (s>mant2_cnt) {

1218 
case 0: 
1219 
s>qmant2_ptr = &qmant[i]; 
1220 
v = 25 * v;

1221 
s>mant2_cnt = 1;

1222 
break;

1223 
case 1: 
1224 
*s>qmant2_ptr += 5 * v;

1225 
s>mant2_cnt = 2;

1226 
v = 128;

1227 
break;

1228 
default:

1229 
*s>qmant2_ptr += v; 
1230 
s>mant2_cnt = 0;

1231 
v = 128;

1232 
break;

1233 
} 
1234 
break;

1235 
case 3: 
1236 
v = sym_quant(c, e, 7);

1237 
break;

1238 
case 4: 
1239 
v = sym_quant(c, e, 11);

1240 
switch (s>mant4_cnt) {

1241 
case 0: 
1242 
s>qmant4_ptr = &qmant[i]; 
1243 
v = 11 * v;

1244 
s>mant4_cnt = 1;

1245 
break;

1246 
default:

1247 
*s>qmant4_ptr += v; 
1248 
s>mant4_cnt = 0;

1249 
v = 128;

1250 
break;

1251 
} 
1252 
break;

1253 
case 5: 
1254 
v = sym_quant(c, e, 15);

1255 
break;

1256 
case 14: 
1257 
v = asym_quant(c, e, 14);

1258 
break;

1259 
case 15: 
1260 
v = asym_quant(c, e, 16);

1261 
break;

1262 
default:

1263 
v = asym_quant(c, e, b  1);

1264 
break;

1265 
} 
1266 
qmant[i] = v; 
1267 
} 
1268 
} 
1269  
1270  
1271 
/**

1272 
* Quantize mantissas using coefficients, exponents, and bit allocation pointers.

1273 
*/

1274 
static void quantize_mantissas(AC3EncodeContext *s) 
1275 
{ 
1276 
int blk, ch;

1277  
1278  
1279 
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) { 
1280 
AC3Block *block = &s>blocks[blk]; 
1281 
s>mant1_cnt = s>mant2_cnt = s>mant4_cnt = 0;

1282 
s>qmant1_ptr = s>qmant2_ptr = s>qmant4_ptr = NULL;

1283  
1284 
for (ch = 0; ch < s>channels; ch++) { 
1285 
quantize_mantissas_blk_ch(s, block>mdct_coef[ch], block>exp_shift[ch], 
1286 
block>exp[ch], block>bap[ch], 
1287 
block>qmant[ch], s>nb_coefs[ch]); 
1288 
} 
1289 
} 
1290 
} 
1291  
1292  
1293 
/**

1294 
* Write the AC3 frame header to the output bitstream.

1295 
*/

1296 
static void output_frame_header(AC3EncodeContext *s) 
1297 
{ 
1298 
put_bits(&s>pb, 16, 0x0b77); /* frame header */ 
1299 
put_bits(&s>pb, 16, 0); /* crc1: will be filled later */ 
1300 
put_bits(&s>pb, 2, s>bit_alloc.sr_code);

1301 
put_bits(&s>pb, 6, s>frame_size_code + (s>frame_size  s>frame_size_min) / 2); 
1302 
put_bits(&s>pb, 5, s>bitstream_id);

1303 
put_bits(&s>pb, 3, s>bitstream_mode);

1304 
put_bits(&s>pb, 3, s>channel_mode);

1305 
if ((s>channel_mode & 0x01) && s>channel_mode != AC3_CHMODE_MONO) 
1306 
put_bits(&s>pb, 2, 1); /* XXX 4.5 dB */ 
1307 
if (s>channel_mode & 0x04) 
1308 
put_bits(&s>pb, 2, 1); /* XXX 6 dB */ 
1309 
if (s>channel_mode == AC3_CHMODE_STEREO)

1310 
put_bits(&s>pb, 2, 0); /* surround not indicated */ 
1311 
put_bits(&s>pb, 1, s>lfe_on); /* LFE */ 
1312 
put_bits(&s>pb, 5, 31); /* dialog norm: 31 db */ 
1313 
put_bits(&s>pb, 1, 0); /* no compression control word */ 
1314 
put_bits(&s>pb, 1, 0); /* no lang code */ 
1315 
put_bits(&s>pb, 1, 0); /* no audio production info */ 
1316 
put_bits(&s>pb, 1, 0); /* no copyright */ 
1317 
put_bits(&s>pb, 1, 1); /* original bitstream */ 
1318 
put_bits(&s>pb, 1, 0); /* no time code 1 */ 
1319 
put_bits(&s>pb, 1, 0); /* no time code 2 */ 
1320 
put_bits(&s>pb, 1, 0); /* no additional bit stream info */ 
1321 
} 
1322  
1323  
1324 
/**

1325 
* Write one audio block to the output bitstream.

1326 
*/

1327 
static void output_audio_block(AC3EncodeContext *s, 
1328 
int block_num)

1329 
{ 
1330 
int ch, i, baie, rbnd;

1331 
AC3Block *block = &s>blocks[block_num]; 
1332  
1333 
/* block switching */

1334 
for (ch = 0; ch < s>fbw_channels; ch++) 
1335 
put_bits(&s>pb, 1, 0); 
1336  
1337 
/* dither flags */

1338 
for (ch = 0; ch < s>fbw_channels; ch++) 
1339 
put_bits(&s>pb, 1, 1); 
1340  
1341 
/* dynamic range codes */

1342 
put_bits(&s>pb, 1, 0); 
1343  
1344 
/* channel coupling */

1345 
if (!block_num) {

1346 
put_bits(&s>pb, 1, 1); /* coupling strategy present */ 
1347 
put_bits(&s>pb, 1, 0); /* no coupling strategy */ 
1348 
} else {

1349 
put_bits(&s>pb, 1, 0); /* no new coupling strategy */ 
1350 
} 
1351  
1352 
/* stereo rematrixing */

1353 
if (s>channel_mode == AC3_CHMODE_STEREO) {

1354 
if (!block_num) {

1355 
/* first block must define rematrixing (rematstr) */

1356 
put_bits(&s>pb, 1, 1); 
1357  
1358 
/* dummy rematrixing rematflg(1:4)=0 */

1359 
for (rbnd = 0; rbnd < 4; rbnd++) 
1360 
put_bits(&s>pb, 1, 0); 
1361 
} else {

1362 
/* no matrixing (but should be used in the future) */

1363 
put_bits(&s>pb, 1, 0); 
1364 
} 
1365 
} 
1366  
1367 
/* exponent strategy */

1368 
for (ch = 0; ch < s>fbw_channels; ch++) 
1369 
put_bits(&s>pb, 2, block>exp_strategy[ch]);

1370 
if (s>lfe_on)

1371 
put_bits(&s>pb, 1, block>exp_strategy[s>lfe_channel]);

1372  
1373 
/* bandwidth */

1374 
for (ch = 0; ch < s>fbw_channels; ch++) { 
1375 
if (block>exp_strategy[ch] != EXP_REUSE)

1376 
put_bits(&s>pb, 6, s>bandwidth_code[ch]);

1377 
} 
1378  
1379 
/* exponents */

1380 
for (ch = 0; ch < s>channels; ch++) { 
1381 
int nb_groups;

1382  
1383 
if (block>exp_strategy[ch] == EXP_REUSE)

1384 
continue;

1385  
1386 
/* DC exponent */

1387 
put_bits(&s>pb, 4, block>grouped_exp[ch][0]); 
1388  
1389 
/* exponent groups */

1390 
nb_groups = exponent_group_tab[block>exp_strategy[ch]1][s>nb_coefs[ch]];

1391 
for (i = 1; i <= nb_groups; i++) 
1392 
put_bits(&s>pb, 7, block>grouped_exp[ch][i]);

1393  
1394 
/* gain range info */

1395 
if (ch != s>lfe_channel)

1396 
put_bits(&s>pb, 2, 0); 
1397 
} 
1398  
1399 
/* bit allocation info */

1400 
baie = (block_num == 0);

1401 
put_bits(&s>pb, 1, baie);

1402 
if (baie) {

1403 
put_bits(&s>pb, 2, s>slow_decay_code);

1404 
put_bits(&s>pb, 2, s>fast_decay_code);

1405 
put_bits(&s>pb, 2, s>slow_gain_code);

1406 
put_bits(&s>pb, 2, s>db_per_bit_code);

1407 
put_bits(&s>pb, 3, s>floor_code);

1408 
} 
1409  
1410 
/* snr offset */

1411 
put_bits(&s>pb, 1, baie);

1412 
if (baie) {

1413 
put_bits(&s>pb, 6, s>coarse_snr_offset);

1414 
for (ch = 0; ch < s>channels; ch++) { 
1415 
put_bits(&s>pb, 4, s>fine_snr_offset[ch]);

1416 
put_bits(&s>pb, 3, s>fast_gain_code[ch]);

1417 
} 
1418 
} 
1419  
1420 
put_bits(&s>pb, 1, 0); /* no delta bit allocation */ 
1421 
put_bits(&s>pb, 1, 0); /* no data to skip */ 
1422  
1423 
/* mantissas */

1424 
for (ch = 0; ch < s>channels; ch++) { 
1425 
int b, q;

1426 
for (i = 0; i < s>nb_coefs[ch]; i++) { 
1427 
q = block>qmant[ch][i]; 
1428 
b = block>bap[ch][i]; 
1429 
switch (b) {

1430 
case 0: break; 
1431 
case 1: if (q != 128) put_bits(&s>pb, 5, q); break; 
1432 
case 2: if (q != 128) put_bits(&s>pb, 7, q); break; 
1433 
case 3: put_bits(&s>pb, 3, q); break; 
1434 
case 4: if (q != 128) put_bits(&s>pb, 7, q); break; 
1435 
case 14: put_bits(&s>pb, 14, q); break; 
1436 
case 15: put_bits(&s>pb, 16, q); break; 
1437 
default: put_bits(&s>pb, b1, q); break; 
1438 
} 
1439 
} 
1440 
} 
1441 
} 
1442  
1443  
1444 
/** CRC16 Polynomial */

1445 
#define CRC16_POLY ((1 << 0)  (1 << 2)  (1 << 15)  (1 << 16)) 
1446  
1447  
1448 
static unsigned int mul_poly(unsigned int a, unsigned int b, unsigned int poly) 
1449 
{ 
1450 
unsigned int c; 
1451  
1452 
c = 0;

1453 
while (a) {

1454 
if (a & 1) 
1455 
c ^= b; 
1456 
a = a >> 1;

1457 
b = b << 1;

1458 
if (b & (1 << 16)) 
1459 
b ^= poly; 
1460 
} 
1461 
return c;

1462 
} 
1463  
1464  
1465 
static unsigned int pow_poly(unsigned int a, unsigned int n, unsigned int poly) 
1466 
{ 
1467 
unsigned int r; 
1468 
r = 1;

1469 
while (n) {

1470 
if (n & 1) 
1471 
r = mul_poly(r, a, poly); 
1472 
a = mul_poly(a, a, poly); 
1473 
n >>= 1;

1474 
} 
1475 
return r;

1476 
} 
1477  
1478  
1479 
/**

1480 
* Fill the end of the frame with 0's and compute the two CRCs.

1481 
*/

1482 
static void output_frame_end(AC3EncodeContext *s) 
1483 
{ 
1484 
int frame_size, frame_size_58, pad_bytes, crc1, crc2, crc_inv;

1485 
uint8_t *frame; 
1486  
1487 
frame_size = s>frame_size; 
1488 
frame_size_58 = ((frame_size >> 2) + (frame_size >> 4)) << 1; 
1489  
1490 
/* pad the remainder of the frame with zeros */

1491 
flush_put_bits(&s>pb); 
1492 
frame = s>pb.buf; 
1493 
pad_bytes = s>frame_size  (put_bits_ptr(&s>pb)  frame)  2;

1494 
assert(pad_bytes >= 0);

1495 
if (pad_bytes > 0) 
1496 
memset(put_bits_ptr(&s>pb), 0, pad_bytes);

1497  
1498 
/* compute crc1 */

1499 
/* this is not so easy because it is at the beginning of the data... */

1500 
crc1 = av_bswap16(av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0,

1501 
frame + 4, frame_size_58  4)); 
1502 
/* XXX: could precompute crc_inv */

1503 
crc_inv = pow_poly((CRC16_POLY >> 1), (8 * frame_size_58)  16, CRC16_POLY); 
1504 
crc1 = mul_poly(crc_inv, crc1, CRC16_POLY); 
1505 
AV_WB16(frame + 2, crc1);

1506  
1507 
/* compute crc2 */

1508 
crc2 = av_bswap16(av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0,

1509 
frame + frame_size_58, 
1510 
frame_size  frame_size_58  2));

1511 
AV_WB16(frame + frame_size  2, crc2);

1512 
} 
1513  
1514  
1515 
/**

1516 
* Write the frame to the output bitstream.

1517 
*/

1518 
static void output_frame(AC3EncodeContext *s, 
1519 
unsigned char *frame) 
1520 
{ 
1521 
int blk;

1522  
1523 
init_put_bits(&s>pb, frame, AC3_MAX_CODED_FRAME_SIZE); 
1524  
1525 
output_frame_header(s); 
1526  
1527 
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) 
1528 
output_audio_block(s, blk); 
1529  
1530 
output_frame_end(s); 
1531 
} 
1532  
1533  
1534 
/**

1535 
* Encode a single AC3 frame.

1536 
*/

1537 
static int ac3_encode_frame(AVCodecContext *avctx, 
1538 
unsigned char *frame, int buf_size, void *data) 
1539 
{ 
1540 
AC3EncodeContext *s = avctx>priv_data; 
1541 
const int16_t *samples = data;

1542 
int ret;

1543  
1544 
if (s>bit_alloc.sr_code == 1) 
1545 
adjust_frame_size(s); 
1546  
1547 
deinterleave_input_samples(s, samples); 
1548  
1549 
apply_mdct(s); 
1550  
1551 
process_exponents(s); 
1552  
1553 
ret = compute_bit_allocation(s); 
1554 
if (ret) {

1555 
av_log(avctx, AV_LOG_ERROR, "Bit allocation failed. Try increasing the bitrate.\n");

1556 
return ret;

1557 
} 
1558  
1559 
quantize_mantissas(s); 
1560  
1561 
output_frame(s, frame); 
1562  
1563 
return s>frame_size;

1564 
} 
1565  
1566  
1567 
/**

1568 
* Finalize encoding and free any memory allocated by the encoder.

1569 
*/

1570 
static av_cold int ac3_encode_close(AVCodecContext *avctx) 
1571 
{ 
1572 
int blk, ch;

1573 
AC3EncodeContext *s = avctx>priv_data; 
1574  
1575 
for (ch = 0; ch < s>channels; ch++) 
1576 
av_freep(&s>planar_samples[ch]); 
1577 
av_freep(&s>planar_samples); 
1578 
av_freep(&s>bap_buffer); 
1579 
av_freep(&s>bap1_buffer); 
1580 
av_freep(&s>mdct_coef_buffer); 
1581 
av_freep(&s>exp_buffer); 
1582 
av_freep(&s>grouped_exp_buffer); 
1583 
av_freep(&s>psd_buffer); 
1584 
av_freep(&s>band_psd_buffer); 
1585 
av_freep(&s>mask_buffer); 
1586 
av_freep(&s>qmant_buffer); 
1587 
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) { 
1588 
AC3Block *block = &s>blocks[blk]; 
1589 
av_freep(&block>bap); 
1590 
av_freep(&block>mdct_coef); 
1591 
av_freep(&block>exp); 
1592 
av_freep(&block>grouped_exp); 
1593 
av_freep(&block>psd); 
1594 
av_freep(&block>band_psd); 
1595 
av_freep(&block>mask); 
1596 
av_freep(&block>qmant); 
1597 
} 
1598  
1599 
mdct_end(&s>mdct); 
1600  
1601 
av_freep(&avctx>coded_frame); 
1602 
return 0; 
1603 
} 
1604  
1605  
1606 
/**

1607 
* Set channel information during initialization.

1608 
*/

1609 
static av_cold int set_channel_info(AC3EncodeContext *s, int channels, 
1610 
int64_t *channel_layout) 
1611 
{ 
1612 
int ch_layout;

1613  
1614 
if (channels < 1  channels > AC3_MAX_CHANNELS) 
1615 
return AVERROR(EINVAL);

1616 
if ((uint64_t)*channel_layout > 0x7FF) 
1617 
return AVERROR(EINVAL);

1618 
ch_layout = *channel_layout; 
1619 
if (!ch_layout)

1620 
ch_layout = avcodec_guess_channel_layout(channels, CODEC_ID_AC3, NULL);

1621 
if (av_get_channel_layout_nb_channels(ch_layout) != channels)

1622 
return AVERROR(EINVAL);

1623  
1624 
s>lfe_on = !!(ch_layout & AV_CH_LOW_FREQUENCY); 
1625 
s>channels = channels; 
1626 
s>fbw_channels = channels  s>lfe_on; 
1627 
s>lfe_channel = s>lfe_on ? s>fbw_channels : 1;

1628 
if (s>lfe_on)

1629 
ch_layout = AV_CH_LOW_FREQUENCY; 
1630  
1631 
switch (ch_layout) {

1632 
case AV_CH_LAYOUT_MONO: s>channel_mode = AC3_CHMODE_MONO; break; 
1633 
case AV_CH_LAYOUT_STEREO: s>channel_mode = AC3_CHMODE_STEREO; break; 
1634 
case AV_CH_LAYOUT_SURROUND: s>channel_mode = AC3_CHMODE_3F; break; 
1635 
case AV_CH_LAYOUT_2_1: s>channel_mode = AC3_CHMODE_2F1R; break; 
1636 
case AV_CH_LAYOUT_4POINT0: s>channel_mode = AC3_CHMODE_3F1R; break; 
1637 
case AV_CH_LAYOUT_QUAD:

1638 
case AV_CH_LAYOUT_2_2: s>channel_mode = AC3_CHMODE_2F2R; break; 
1639 
case AV_CH_LAYOUT_5POINT0:

1640 
case AV_CH_LAYOUT_5POINT0_BACK: s>channel_mode = AC3_CHMODE_3F2R; break; 
1641 
default:

1642 
return AVERROR(EINVAL);

1643 
} 
1644  
1645 
s>channel_map = ff_ac3_enc_channel_map[s>channel_mode][s>lfe_on]; 
1646 
*channel_layout = ch_layout; 
1647 
if (s>lfe_on)

1648 
*channel_layout = AV_CH_LOW_FREQUENCY; 
1649  
1650 
return 0; 
1651 
} 
1652  
1653  
1654 
static av_cold int validate_options(AVCodecContext *avctx, AC3EncodeContext *s) 
1655 
{ 
1656 
int i, ret;

1657  
1658 
/* validate channel layout */

1659 
if (!avctx>channel_layout) {

1660 
av_log(avctx, AV_LOG_WARNING, "No channel layout specified. The "

1661 
"encoder will guess the layout, but it "

1662 
"might be incorrect.\n");

1663 
} 
1664 
ret = set_channel_info(s, avctx>channels, &avctx>channel_layout); 
1665 
if (ret) {

1666 
av_log(avctx, AV_LOG_ERROR, "invalid channel layout\n");

1667 
return ret;

1668 
} 
1669  
1670 
/* validate sample rate */

1671 
for (i = 0; i < 9; i++) { 
1672 
if ((ff_ac3_sample_rate_tab[i / 3] >> (i % 3)) == avctx>sample_rate) 
1673 
break;

1674 
} 
1675 
if (i == 9) { 
1676 
av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n");

1677 
return AVERROR(EINVAL);

1678 
} 
1679 
s>sample_rate = avctx>sample_rate; 
1680 
s>bit_alloc.sr_shift = i % 3;

1681 
s>bit_alloc.sr_code = i / 3;

1682  
1683 
/* validate bit rate */

1684 
for (i = 0; i < 19; i++) { 
1685 
if ((ff_ac3_bitrate_tab[i] >> s>bit_alloc.sr_shift)*1000 == avctx>bit_rate) 
1686 
break;

1687 
} 
1688 
if (i == 19) { 
1689 
av_log(avctx, AV_LOG_ERROR, "invalid bit rate\n");

1690 
return AVERROR(EINVAL);

1691 
} 
1692 
s>bit_rate = avctx>bit_rate; 
1693 
s>frame_size_code = i << 1;

1694  
1695 
/* validate cutoff */

1696 
if (avctx>cutoff < 0) { 
1697 
av_log(avctx, AV_LOG_ERROR, "invalid cutoff frequency\n");

1698 
return AVERROR(EINVAL);

1699 
} 
1700 
s>cutoff = avctx>cutoff; 
1701 
if (s>cutoff > (s>sample_rate >> 1)) 
1702 
s>cutoff = s>sample_rate >> 1;

1703  
1704 
return 0; 
1705 
} 
1706  
1707  
1708 
/**

1709 
* Set bandwidth for all channels.

1710 
* The user can optionally supply a cutoff frequency. Otherwise an appropriate

1711 
* default value will be used.

1712 
*/

1713 
static av_cold void set_bandwidth(AC3EncodeContext *s) 
1714 
{ 
1715 
int ch, bw_code;

1716  
1717 
if (s>cutoff) {

1718 
/* calculate bandwidth based on userspecified cutoff frequency */

1719 
int fbw_coeffs;

1720 
fbw_coeffs = s>cutoff * 2 * AC3_MAX_COEFS / s>sample_rate;

1721 
bw_code = av_clip((fbw_coeffs  73) / 3, 0, 60); 
1722 
} else {

1723 
/* use default bandwidth setting */

1724 
/* XXX: should compute the bandwidth according to the frame

1725 
size, so that we avoid annoying high frequency artifacts */

1726 
bw_code = 50;

1727 
} 
1728  
1729 
/* set number of coefficients for each channel */

1730 
for (ch = 0; ch < s>fbw_channels; ch++) { 
1731 
s>bandwidth_code[ch] = bw_code; 
1732 
s>nb_coefs[ch] = bw_code * 3 + 73; 
1733 
} 
1734 
if (s>lfe_on)

1735 
s>nb_coefs[s>lfe_channel] = 7; /* LFE channel always has 7 coefs */ 
1736 
} 
1737  
1738  
1739 
static av_cold int allocate_buffers(AVCodecContext *avctx) 
1740 
{ 
1741 
int blk, ch;

1742 
AC3EncodeContext *s = avctx>priv_data; 
1743  
1744 
FF_ALLOC_OR_GOTO(avctx, s>planar_samples, s>channels * sizeof(*s>planar_samples),

1745 
alloc_fail); 
1746 
for (ch = 0; ch < s>channels; ch++) { 
1747 
FF_ALLOCZ_OR_GOTO(avctx, s>planar_samples[ch], 
1748 
(AC3_FRAME_SIZE+AC3_BLOCK_SIZE) * sizeof(**s>planar_samples),

1749 
alloc_fail); 
1750 
} 
1751 
FF_ALLOC_OR_GOTO(avctx, s>bap_buffer, AC3_MAX_BLOCKS * s>channels * 
1752 
AC3_MAX_COEFS * sizeof(*s>bap_buffer), alloc_fail);

1753 
FF_ALLOC_OR_GOTO(avctx, s>bap1_buffer, AC3_MAX_BLOCKS * s>channels * 
1754 
AC3_MAX_COEFS * sizeof(*s>bap1_buffer), alloc_fail);

1755 
FF_ALLOC_OR_GOTO(avctx, s>mdct_coef_buffer, AC3_MAX_BLOCKS * s>channels * 
1756 
AC3_MAX_COEFS * sizeof(*s>mdct_coef_buffer), alloc_fail);

1757 
FF_ALLOC_OR_GOTO(avctx, s>exp_buffer, AC3_MAX_BLOCKS * s>channels * 
1758 
AC3_MAX_COEFS * sizeof(*s>exp_buffer), alloc_fail);

1759 
FF_ALLOC_OR_GOTO(avctx, s>grouped_exp_buffer, AC3_MAX_BLOCKS * s>channels * 
1760 
128 * sizeof(*s>grouped_exp_buffer), alloc_fail); 
1761 
FF_ALLOC_OR_GOTO(avctx, s>psd_buffer, AC3_MAX_BLOCKS * s>channels * 
1762 
AC3_MAX_COEFS * sizeof(*s>psd_buffer), alloc_fail);

1763 
FF_ALLOC_OR_GOTO(avctx, s>band_psd_buffer, AC3_MAX_BLOCKS * s>channels * 
1764 
64 * sizeof(*s>band_psd_buffer), alloc_fail); 
1765 
FF_ALLOC_OR_GOTO(avctx, s>mask_buffer, AC3_MAX_BLOCKS * s>channels * 
1766 
64 * sizeof(*s>mask_buffer), alloc_fail); 
1767 
FF_ALLOC_OR_GOTO(avctx, s>qmant_buffer, AC3_MAX_BLOCKS * s>channels * 
1768 
AC3_MAX_COEFS * sizeof(*s>qmant_buffer), alloc_fail);

1769 
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) { 
1770 
AC3Block *block = &s>blocks[blk]; 
1771 
FF_ALLOC_OR_GOTO(avctx, block>bap, s>channels * sizeof(*block>bap),

1772 
alloc_fail); 
1773 
FF_ALLOCZ_OR_GOTO(avctx, block>mdct_coef, s>channels * sizeof(*block>mdct_coef),

1774 
alloc_fail); 
1775 
FF_ALLOCZ_OR_GOTO(avctx, block>exp, s>channels * sizeof(*block>exp),

1776 
alloc_fail); 
1777 
FF_ALLOCZ_OR_GOTO(avctx, block>grouped_exp, s>channels * sizeof(*block>grouped_exp),

1778 
alloc_fail); 
1779 
FF_ALLOCZ_OR_GOTO(avctx, block>psd, s>channels * sizeof(*block>psd),

1780 
alloc_fail); 
1781 
FF_ALLOCZ_OR_GOTO(avctx, block>band_psd, s>channels * sizeof(*block>band_psd),

1782 
alloc_fail); 
1783 
FF_ALLOCZ_OR_GOTO(avctx, block>mask, s>channels * sizeof(*block>mask),

1784 
alloc_fail); 
1785 
FF_ALLOCZ_OR_GOTO(avctx, block>qmant, s>channels * sizeof(*block>qmant),

1786 
alloc_fail); 
1787  
1788 
for (ch = 0; ch < s>channels; ch++) { 
1789 
block>bap[ch] = &s>bap_buffer [AC3_MAX_COEFS * (blk * s>channels + ch)]; 
1790 
block>mdct_coef[ch] = &s>mdct_coef_buffer [AC3_MAX_COEFS * (blk * s>channels + ch)]; 
1791 
block>exp[ch] = &s>exp_buffer [AC3_MAX_COEFS * (blk * s>channels + ch)]; 
1792 
block>grouped_exp[ch] = &s>grouped_exp_buffer[128 * (blk * s>channels + ch)];

1793 
block>psd[ch] = &s>psd_buffer [AC3_MAX_COEFS * (blk * s>channels + ch)]; 
1794 
block>band_psd[ch] = &s>band_psd_buffer [64 * (blk * s>channels + ch)];

1795 
block>mask[ch] = &s>mask_buffer [64 * (blk * s>channels + ch)];

1796 
block>qmant[ch] = &s>qmant_buffer [AC3_MAX_COEFS * (blk * s>channels + ch)]; 
1797 
} 
1798 
} 
1799  
1800 
return 0; 
1801 
alloc_fail:

1802 
return AVERROR(ENOMEM);

1803 
} 
1804  
1805  
1806 
/**

1807 
* Initialize the encoder.

1808 
*/

1809 
static av_cold int ac3_encode_init(AVCodecContext *avctx) 
1810 
{ 
1811 
AC3EncodeContext *s = avctx>priv_data; 
1812 
int ret;

1813  
1814 
avctx>frame_size = AC3_FRAME_SIZE; 
1815  
1816 
ac3_common_init(); 
1817  
1818 
ret = validate_options(avctx, s); 
1819 
if (ret)

1820 
return ret;

1821  
1822 
s>bitstream_id = 8 + s>bit_alloc.sr_shift;

1823 
s>bitstream_mode = 0; /* complete main audio service */ 
1824  
1825 
s>frame_size_min = 2 * ff_ac3_frame_size_tab[s>frame_size_code][s>bit_alloc.sr_code];

1826 
s>bits_written = 0;

1827 
s>samples_written = 0;

1828 
s>frame_size = s>frame_size_min; 
1829  
1830 
set_bandwidth(s); 
1831  
1832 
exponent_init(s); 
1833  
1834 
bit_alloc_init(s); 
1835  
1836 
s>mdct.avctx = avctx; 
1837 
ret = mdct_init(&s>mdct, 9);

1838 
if (ret)

1839 
goto init_fail;

1840  
1841 
ret = allocate_buffers(avctx); 
1842 
if (ret)

1843 
goto init_fail;

1844  
1845 
avctx>coded_frame= avcodec_alloc_frame(); 
1846  
1847 
dsputil_init(&s>dsp, avctx); 
1848  
1849 
return 0; 
1850 
init_fail:

1851 
ac3_encode_close(avctx); 
1852 
return ret;

1853 
} 
1854  
1855  
1856 
#ifdef TEST

1857 
/*************************************************************************/

1858 
/* TEST */

1859  
1860 
#include "libavutil/lfg.h" 
1861  
1862 
#define MDCT_NBITS 9 
1863 
#define MDCT_SAMPLES (1 << MDCT_NBITS) 
1864 
#define FN (MDCT_SAMPLES/4) 
1865  
1866  
1867 
static void fft_test(AC3MDCTContext *mdct, AVLFG *lfg) 
1868 
{ 
1869 
IComplex in[FN], in1[FN]; 
1870 
int k, n, i;

1871 
float sum_re, sum_im, a;

1872  
1873 
for (i = 0; i < FN; i++) { 
1874 
in[i].re = av_lfg_get(lfg) % 65535  32767; 
1875 
in[i].im = av_lfg_get(lfg) % 65535  32767; 
1876 
in1[i] = in[i]; 
1877 
} 
1878 
fft(mdct, in, 7);

1879  
1880 
/* do it by hand */

1881 
for (k = 0; k < FN; k++) { 
1882 
sum_re = 0;

1883 
sum_im = 0;

1884 
for (n = 0; n < FN; n++) { 
1885 
a = 2 * M_PI * (n * k) / FN;

1886 
sum_re += in1[n].re * cos(a)  in1[n].im * sin(a); 
1887 
sum_im += in1[n].re * sin(a) + in1[n].im * cos(a); 
1888 
} 
1889 
av_log(NULL, AV_LOG_DEBUG, "%3d: %6d,%6d %6.0f,%6.0f\n", 
1890 
k, in[k].re, in[k].im, sum_re / FN, sum_im / FN); 
1891 
} 
1892 
} 
1893  
1894  
1895 
static void mdct_test(AC3MDCTContext *mdct, AVLFG *lfg) 
1896 
{ 
1897 
int16_t input[MDCT_SAMPLES]; 
1898 
int32_t output[AC3_MAX_COEFS]; 
1899 
float input1[MDCT_SAMPLES];

1900 
float output1[AC3_MAX_COEFS];

1901 
float s, a, err, e, emax;

1902 
int i, k, n;

1903  
1904 
for (i = 0; i < MDCT_SAMPLES; i++) { 
1905 
input[i] = (av_lfg_get(lfg) % 65535  32767) * 9 / 10; 
1906 
input1[i] = input[i]; 
1907 
} 
1908  
1909 
mdct512(mdct, output, input); 
1910  
1911 
/* do it by hand */

1912 
for (k = 0; k < AC3_MAX_COEFS; k++) { 
1913 
s = 0;

1914 
for (n = 0; n < MDCT_SAMPLES; n++) { 
1915 
a = (2*M_PI*(2*n+1+MDCT_SAMPLES/2)*(2*k+1) / (4 * MDCT_SAMPLES)); 
1916 
s += input1[n] * cos(a); 
1917 
} 
1918 
output1[k] = 2 * s / MDCT_SAMPLES;

1919 
} 
1920  
1921 
err = 0;

1922 
emax = 0;

1923 
for (i = 0; i < AC3_MAX_COEFS; i++) { 
1924 
av_log(NULL, AV_LOG_DEBUG, "%3d: %7d %7.0f\n", i, output[i], output1[i]); 
1925 
e = output[i]  output1[i]; 
1926 
if (e > emax)

1927 
emax = e; 
1928 
err += e * e; 
1929 
} 
1930 
av_log(NULL, AV_LOG_DEBUG, "err2=%f emax=%f\n", err / AC3_MAX_COEFS, emax); 
1931 
} 
1932  
1933  
1934 
int main(void) 
1935 
{ 
1936 
AVLFG lfg; 
1937 
AC3MDCTContext mdct; 
1938  
1939 
mdct.avctx = NULL;

1940 
av_log_set_level(AV_LOG_DEBUG); 
1941 
mdct_init(&mdct, 9);

1942  
1943 
fft_test(&mdct, &lfg); 
1944 
mdct_test(&mdct, &lfg); 
1945  
1946 
return 0; 
1947 
} 
1948 
#endif /* TEST */ 
1949  
1950  
1951 
AVCodec ac3_encoder = { 
1952 
"ac3",

1953 
AVMEDIA_TYPE_AUDIO, 
1954 
CODEC_ID_AC3, 
1955 
sizeof(AC3EncodeContext),

1956 
ac3_encode_init, 
1957 
ac3_encode_frame, 
1958 
ac3_encode_close, 
1959 
NULL,

1960 
.sample_fmts = (const enum AVSampleFormat[]){AV_SAMPLE_FMT_S16,AV_SAMPLE_FMT_NONE}, 
1961 
.long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC3)"),

1962 
.channel_layouts = (const int64_t[]){

1963 
AV_CH_LAYOUT_MONO, 
1964 
AV_CH_LAYOUT_STEREO, 
1965 
AV_CH_LAYOUT_2_1, 
1966 
AV_CH_LAYOUT_SURROUND, 
1967 
AV_CH_LAYOUT_2_2, 
1968 
AV_CH_LAYOUT_QUAD, 
1969 
AV_CH_LAYOUT_4POINT0, 
1970 
AV_CH_LAYOUT_5POINT0, 
1971 
AV_CH_LAYOUT_5POINT0_BACK, 
1972 
(AV_CH_LAYOUT_MONO  AV_CH_LOW_FREQUENCY), 
1973 
(AV_CH_LAYOUT_STEREO  AV_CH_LOW_FREQUENCY), 
1974 
(AV_CH_LAYOUT_2_1  AV_CH_LOW_FREQUENCY), 
1975 
(AV_CH_LAYOUT_SURROUND  AV_CH_LOW_FREQUENCY), 
1976 
(AV_CH_LAYOUT_2_2  AV_CH_LOW_FREQUENCY), 
1977 
(AV_CH_LAYOUT_QUAD  AV_CH_LOW_FREQUENCY), 
1978 
(AV_CH_LAYOUT_4POINT0  AV_CH_LOW_FREQUENCY), 
1979 
AV_CH_LAYOUT_5POINT1, 
1980 
AV_CH_LAYOUT_5POINT1_BACK, 
1981 
0 },

1982 
}; 