ffmpeg / libavcodec / ac3enc.c @ e86ea34d
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/*


2 
* The simplest AC3 encoder

3 
* Copyright (c) 2000 Fabrice Bellard

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

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

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*

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* This file is part of FFmpeg.

8 
*

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

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

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* License as published by the Free Software Foundation; either

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

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*

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* FFmpeg 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 GNU

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* Lesser General Public License for more details.

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*

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

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

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

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*/

23  
24 
/**

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* @file

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* The simplest AC3 encoder.

27 
*/

28  
29 
//#define DEBUG

30  
31 
#include "libavcore/audioconvert.h" 
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#include "libavutil/crc.h" 
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#include "avcodec.h" 
34 
#include "put_bits.h" 
35 
#include "dsputil.h" 
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#include "ac3.h" 
37 
#include "audioconvert.h" 
38  
39  
40 
#define MDCT_NBITS 9 
41 
#define MDCT_SAMPLES (1 << MDCT_NBITS) 
42  
43 
/** Maximum number of exponent groups. +1 for separate DC exponent. */

44 
#define AC3_MAX_EXP_GROUPS 85 
45  
46 
/** Scale a float value by 2^bits and convert to an integer. */

47 
#define SCALE_FLOAT(a, bits) lrintf((a) * (float)(1 << (bits))) 
48  
49 
/** Scale a float value by 2^15, convert to an integer, and clip to int16_t range. */

50 
#define FIX15(a) av_clip_int16(SCALE_FLOAT(a, 15)) 
51  
52  
53 
/**

54 
* Compex number.

55 
* Used in fixedpoint MDCT calculation.

56 
*/

57 
typedef struct IComplex { 
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int16_t re,im; 
59 
} IComplex; 
60  
61 
typedef struct AC3MDCTContext { 
62 
AVCodecContext *avctx; ///< parent context for av_log()

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

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

65 
} AC3MDCTContext; 
66  
67 
/**

68 
* Data for a single audio block.

69 
*/

70 
typedef struct AC3Block { 
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uint8_t **bap; ///< bit allocation pointers (bap)

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int32_t **mdct_coef; ///< MDCT coefficients

73 
uint8_t **exp; ///< original exponents

74 
uint8_t **grouped_exp; ///< grouped exponents

75 
int16_t **psd; ///< psd per frequency bin

76 
int16_t **band_psd; ///< psd per critical band

77 
int16_t **mask; ///< masking curve

78 
uint16_t **qmant; ///< quantized mantissas

79 
uint8_t exp_strategy[AC3_MAX_CHANNELS]; ///< exponent strategies

80 
int8_t exp_shift[AC3_MAX_CHANNELS]; ///< exponent shift values

81 
} AC3Block; 
82  
83 
/**

84 
* AC3 encoder private context.

85 
*/

86 
typedef struct AC3EncodeContext { 
87 
PutBitContext pb; ///< bitstream writer context

88 
DSPContext dsp; 
89 
AC3MDCTContext mdct; ///< MDCT context

90  
91 
AC3Block blocks[AC3_MAX_BLOCKS]; ///< perblock info

92  
93 
int bitstream_id; ///< bitstream id (bsid) 
94 
int bitstream_mode; ///< bitstream mode (bsmod) 
95  
96 
int bit_rate; ///< target bit rate, in bitspersecond 
97 
int sample_rate; ///< sampling frequency, in Hz 
98  
99 
int frame_size_min; ///< minimum frame size in case rounding is necessary 
100 
int frame_size; ///< current frame size in bytes 
101 
int frame_size_code; ///< frame size code (frmsizecod) 
102 
int bits_written; ///< bit count (used to avg. bitrate) 
103 
int samples_written; ///< sample count (used to avg. bitrate) 
104  
105 
int fbw_channels; ///< number of fullbandwidth channels (nfchans) 
106 
int channels; ///< total number of channels (nchans) 
107 
int lfe_on; ///< indicates if there is an LFE channel (lfeon) 
108 
int lfe_channel; ///< channel index of the LFE channel 
109 
int channel_mode; ///< channel mode (acmod) 
110 
const uint8_t *channel_map; ///< channel map used to reorder channels 
111  
112 
int bandwidth_code[AC3_MAX_CHANNELS]; ///< bandwidth code (0 to 60) (chbwcod) 
113 
int nb_coefs[AC3_MAX_CHANNELS];

114  
115 
/* bitrate allocation control */

116 
int slow_gain_code; ///< slow gain code (sgaincod) 
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int slow_decay_code; ///< slow decay code (sdcycod) 
118 
int fast_decay_code; ///< fast decay code (fdcycod) 
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int db_per_bit_code; ///< dB/bit code (dbpbcod) 
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int floor_code; ///< floor code (floorcod) 
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AC3BitAllocParameters bit_alloc; ///< bit allocation parameters

122 
int coarse_snr_offset; ///< coarse SNR offsets (csnroffst) 
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int fast_gain_code[AC3_MAX_CHANNELS]; ///< fast gain codes (signaltomask ratio) (fgaincod) 
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int fine_snr_offset[AC3_MAX_CHANNELS]; ///< fine SNR offsets (fsnroffst) 
125 
int frame_bits; ///< all frame bits except exponents and mantissas 
126 
int exponent_bits; ///< number of bits used for exponents 
127  
128 
/* mantissa encoding */

129 
int mant1_cnt, mant2_cnt, mant4_cnt; ///< mantissa counts for bap=1,2,4 
130 
uint16_t *qmant1_ptr, *qmant2_ptr, *qmant4_ptr; ///< mantissa pointers for bap=1,2,4

131  
132 
int16_t **planar_samples; 
133 
uint8_t *bap_buffer; 
134 
uint8_t *bap1_buffer; 
135 
int32_t *mdct_coef_buffer; 
136 
uint8_t *exp_buffer; 
137 
uint8_t *grouped_exp_buffer; 
138 
int16_t *psd_buffer; 
139 
int16_t *band_psd_buffer; 
140 
int16_t *mask_buffer; 
141 
uint16_t *qmant_buffer; 
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143 
DECLARE_ALIGNED(16, int16_t, windowed_samples)[AC3_WINDOW_SIZE];

144 
} AC3EncodeContext; 
145  
146  
147 
/** MDCT and FFT tables */

148 
static int16_t costab[64]; 
149 
static int16_t sintab[64]; 
150 
static int16_t xcos1[128]; 
151 
static int16_t xsin1[128]; 
152  
153 
/**

154 
* LUT for number of exponent groups.

155 
* exponent_group_tab[exponent strategy1][number of coefficients]

156 
*/

157 
uint8_t exponent_group_tab[3][256]; 
158  
159  
160 
/**

161 
* Adjust the frame size to make the average bit rate match the target bit rate.

162 
* This is only needed for 11025, 22050, and 44100 sample rates.

163 
*/

164 
static void adjust_frame_size(AC3EncodeContext *s) 
165 
{ 
166 
while (s>bits_written >= s>bit_rate && s>samples_written >= s>sample_rate) {

167 
s>bits_written = s>bit_rate; 
168 
s>samples_written = s>sample_rate; 
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} 
170 
s>frame_size = s>frame_size_min + 
171 
2 * (s>bits_written * s>sample_rate < s>samples_written * s>bit_rate);

172 
s>bits_written += s>frame_size * 8;

173 
s>samples_written += AC3_FRAME_SIZE; 
174 
} 
175  
176  
177 
/**

178 
* Deinterleave input samples.

179 
* Channels are reordered from FFmpeg's default order to AC3 order.

180 
*/

181 
static void deinterleave_input_samples(AC3EncodeContext *s, 
182 
const int16_t *samples)

183 
{ 
184 
int ch, i;

185  
186 
/* deinterleave and remap input samples */

187 
for (ch = 0; ch < s>channels; ch++) { 
188 
const int16_t *sptr;

189 
int sinc;

190  
191 
/* copy last 256 samples of previous frame to the start of the current frame */

192 
memcpy(&s>planar_samples[ch][0], &s>planar_samples[ch][AC3_FRAME_SIZE],

193 
AC3_BLOCK_SIZE * sizeof(s>planar_samples[0][0])); 
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195 
/* deinterleave */

196 
sinc = s>channels; 
197 
sptr = samples + s>channel_map[ch]; 
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for (i = AC3_BLOCK_SIZE; i < AC3_FRAME_SIZE+AC3_BLOCK_SIZE; i++) {

199 
s>planar_samples[ch][i] = *sptr; 
200 
sptr += sinc; 
201 
} 
202 
} 
203 
} 
204  
205  
206 
/**

207 
* Finalize MDCT and free allocated memory.

208 
*/

209 
static av_cold void mdct_end(AC3MDCTContext *mdct) 
210 
{ 
211 
av_freep(&mdct>rot_tmp); 
212 
av_freep(&mdct>cplx_tmp); 
213 
} 
214  
215  
216  
217 
/**

218 
* Initialize FFT tables.

219 
* @param ln log2(FFT size)

220 
*/

221 
static av_cold void fft_init(int ln) 
222 
{ 
223 
int i, n, n2;

224 
float alpha;

225  
226 
n = 1 << ln;

227 
n2 = n >> 1;

228  
229 
for (i = 0; i < n2; i++) { 
230 
alpha = 2.0 * M_PI * i / n; 
231 
costab[i] = FIX15(cos(alpha)); 
232 
sintab[i] = FIX15(sin(alpha)); 
233 
} 
234 
} 
235  
236  
237 
/**

238 
* Initialize MDCT tables.

239 
* @param nbits log2(MDCT size)

240 
*/

241 
static av_cold int mdct_init(AC3MDCTContext *mdct, int nbits) 
242 
{ 
243 
int i, n, n4;

244  
245 
n = 1 << nbits;

246 
n4 = n >> 2;

247  
248 
fft_init(nbits  2);

249  
250 
FF_ALLOC_OR_GOTO(mdct>avctx, mdct>rot_tmp, n * sizeof(*mdct>rot_tmp),

251 
mdct_alloc_fail); 
252 
FF_ALLOC_OR_GOTO(mdct>avctx, mdct>cplx_tmp, n4 * sizeof(*mdct>cplx_tmp),

253 
mdct_alloc_fail); 
254  
255 
for (i = 0; i < n4; i++) { 
256 
float alpha = 2.0 * M_PI * (i + 1.0 / 8.0) / n; 
257 
xcos1[i] = FIX15(cos(alpha)); 
258 
xsin1[i] = FIX15(sin(alpha)); 
259 
} 
260  
261 
return 0; 
262 
mdct_alloc_fail:

263 
return AVERROR(ENOMEM);

264 
} 
265  
266  
267 
/** Butterfly op */

268 
#define BF(pre, pim, qre, qim, pre1, pim1, qre1, qim1) \

269 
{ \ 
270 
int ax, ay, bx, by; \

271 
bx = pre1; \ 
272 
by = pim1; \ 
273 
ax = qre1; \ 
274 
ay = qim1; \ 
275 
pre = (bx + ax) >> 1; \

276 
pim = (by + ay) >> 1; \

277 
qre = (bx  ax) >> 1; \

278 
qim = (by  ay) >> 1; \

279 
} 
280  
281  
282 
/** Complex multiply */

283 
#define CMUL(pre, pim, are, aim, bre, bim) \

284 
{ \ 
285 
pre = (MUL16(are, bre)  MUL16(aim, bim)) >> 15; \

286 
pim = (MUL16(are, bim) + MUL16(bre, aim)) >> 15; \

287 
} 
288  
289  
290 
/**

291 
* Calculate a 2^n point complex FFT on 2^ln points.

292 
* @param z complex input/output samples

293 
* @param ln log2(FFT size)

294 
*/

295 
static void fft(IComplex *z, int ln) 
296 
{ 
297 
int j, l, np, np2;

298 
int nblocks, nloops;

299 
register IComplex *p,*q;

300 
int tmp_re, tmp_im;

301  
302 
np = 1 << ln;

303  
304 
/* reverse */

305 
for (j = 0; j < np; j++) { 
306 
int k = av_reverse[j] >> (8  ln); 
307 
if (k < j)

308 
FFSWAP(IComplex, z[k], z[j]); 
309 
} 
310  
311 
/* pass 0 */

312  
313 
p = &z[0];

314 
j = np >> 1;

315 
do {

316 
BF(p[0].re, p[0].im, p[1].re, p[1].im, 
317 
p[0].re, p[0].im, p[1].re, p[1].im); 
318 
p += 2;

319 
} while (j);

320  
321 
/* pass 1 */

322  
323 
p = &z[0];

324 
j = np >> 2;

325 
do {

326 
BF(p[0].re, p[0].im, p[2].re, p[2].im, 
327 
p[0].re, p[0].im, p[2].re, p[2].im); 
328 
BF(p[1].re, p[1].im, p[3].re, p[3].im, 
329 
p[1].re, p[1].im, p[3].im, p[3].re); 
330 
p+=4;

331 
} while (j);

332  
333 
/* pass 2 .. ln1 */

334  
335 
nblocks = np >> 3;

336 
nloops = 1 << 2; 
337 
np2 = np >> 1;

338 
do {

339 
p = z; 
340 
q = z + nloops; 
341 
for (j = 0; j < nblocks; j++) { 
342 
BF(p>re, p>im, q>re, q>im, 
343 
p>re, p>im, q>re, q>im); 
344 
p++; 
345 
q++; 
346 
for(l = nblocks; l < np2; l += nblocks) {

347 
CMUL(tmp_re, tmp_im, costab[l], sintab[l], q>re, q>im); 
348 
BF(p>re, p>im, q>re, q>im, 
349 
p>re, p>im, tmp_re, tmp_im); 
350 
p++; 
351 
q++; 
352 
} 
353 
p += nloops; 
354 
q += nloops; 
355 
} 
356 
nblocks = nblocks >> 1;

357 
nloops = nloops << 1;

358 
} while (nblocks);

359 
} 
360  
361  
362 
/**

363 
* Calculate a 512point MDCT

364 
* @param out 256 output frequency coefficients

365 
* @param in 512 windowed input audio samples

366 
*/

367 
static void mdct512(AC3MDCTContext *mdct, int32_t *out, int16_t *in) 
368 
{ 
369 
int i, re, im;

370 
int16_t *rot = mdct>rot_tmp; 
371 
IComplex *x = mdct>cplx_tmp; 
372  
373 
/* shift to simplify computations */

374 
for (i = 0; i < MDCT_SAMPLES/4; i++) 
375 
rot[i] = in[i + 3*MDCT_SAMPLES/4]; 
376 
memcpy(&rot[MDCT_SAMPLES/4], &in[0], 3*MDCT_SAMPLES/4*sizeof(*in)); 
377  
378 
/* pre rotation */

379 
for (i = 0; i < MDCT_SAMPLES/4; i++) { 
380 
re = ((int)rot[ 2*i]  (int)rot[MDCT_SAMPLES 12*i]) >> 1; 
381 
im = ((int)rot[MDCT_SAMPLES/2+2*i]  (int)rot[MDCT_SAMPLES/212*i]) >> 1; 
382 
CMUL(x[i].re, x[i].im, re, im, xcos1[i], xsin1[i]); 
383 
} 
384  
385 
fft(x, MDCT_NBITS  2);

386  
387 
/* post rotation */

388 
for (i = 0; i < MDCT_SAMPLES/4; i++) { 
389 
re = x[i].re; 
390 
im = x[i].im; 
391 
CMUL(out[MDCT_SAMPLES/212*i], out[2*i], re, im, xsin1[i], xcos1[i]); 
392 
} 
393 
} 
394  
395  
396 
/**

397 
* Apply KBD window to input samples prior to MDCT.

398 
*/

399 
static void apply_window(int16_t *output, const int16_t *input, 
400 
const int16_t *window, int n) 
401 
{ 
402 
int i;

403 
int n2 = n >> 1; 
404  
405 
for (i = 0; i < n2; i++) { 
406 
output[i] = MUL16(input[i], window[i]) >> 15;

407 
output[ni1] = MUL16(input[ni1], window[i]) >> 15; 
408 
} 
409 
} 
410  
411  
412 
/**

413 
* Calculate the log2() of the maximum absolute value in an array.

414 
* @param tab input array

415 
* @param n number of values in the array

416 
* @return log2(max(abs(tab[])))

417 
*/

418 
static int log2_tab(int16_t *tab, int n) 
419 
{ 
420 
int i, v;

421  
422 
v = 0;

423 
for (i = 0; i < n; i++) 
424 
v = abs(tab[i]); 
425  
426 
return av_log2(v);

427 
} 
428  
429  
430 
/**

431 
* Leftshift each value in an array by a specified amount.

432 
* @param tab input array

433 
* @param n number of values in the array

434 
* @param lshift left shift amount. a negative value means right shift.

435 
*/

436 
static void lshift_tab(int16_t *tab, int n, int lshift) 
437 
{ 
438 
int i;

439  
440 
if (lshift > 0) { 
441 
for (i = 0; i < n; i++) 
442 
tab[i] <<= lshift; 
443 
} else if (lshift < 0) { 
444 
lshift = lshift; 
445 
for (i = 0; i < n; i++) 
446 
tab[i] >>= lshift; 
447 
} 
448 
} 
449  
450  
451 
/**

452 
* Normalize the input samples to use the maximum available precision.

453 
* This assumes signed 16bit input samples. Exponents are reduced by 9 to

454 
* match the 24bit internal precision for MDCT coefficients.

455 
*

456 
* @return exponent shift

457 
*/

458 
static int normalize_samples(AC3EncodeContext *s) 
459 
{ 
460 
int v = 14  log2_tab(s>windowed_samples, AC3_WINDOW_SIZE); 
461 
v = FFMAX(0, v);

462 
lshift_tab(s>windowed_samples, AC3_WINDOW_SIZE, v); 
463 
return v  9; 
464 
} 
465  
466  
467 
/**

468 
* Apply the MDCT to input samples to generate frequency coefficients.

469 
* This applies the KBD window and normalizes the input to reduce precision

470 
* loss due to fixedpoint calculations.

471 
*/

472 
static void apply_mdct(AC3EncodeContext *s) 
473 
{ 
474 
int blk, ch;

475  
476 
for (ch = 0; ch < s>channels; ch++) { 
477 
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) { 
478 
AC3Block *block = &s>blocks[blk]; 
479 
const int16_t *input_samples = &s>planar_samples[ch][blk * AC3_BLOCK_SIZE];

480  
481 
apply_window(s>windowed_samples, input_samples, ff_ac3_window, AC3_WINDOW_SIZE); 
482  
483 
block>exp_shift[ch] = normalize_samples(s); 
484  
485 
mdct512(&s>mdct, block>mdct_coef[ch], s>windowed_samples); 
486 
} 
487 
} 
488 
} 
489  
490  
491 
/**

492 
* Initialize exponent tables.

493 
*/

494 
static av_cold void exponent_init(AC3EncodeContext *s) 
495 
{ 
496 
int i;

497 
for (i = 73; i < 256; i++) { 
498 
exponent_group_tab[0][i] = (i  1) / 3; 
499 
exponent_group_tab[1][i] = (i + 2) / 6; 
500 
exponent_group_tab[2][i] = (i + 8) / 12; 
501 
} 
502 
} 
503  
504  
505 
/**

506 
* Extract exponents from the MDCT coefficients.

507 
* This takes into account the normalization that was done to the input samples

508 
* by adjusting the exponents by the exponent shift values.

509 
*/

510 
static void extract_exponents(AC3EncodeContext *s) 
511 
{ 
512 
int blk, ch, i;

513  
514 
for (ch = 0; ch < s>channels; ch++) { 
515 
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) { 
516 
AC3Block *block = &s>blocks[blk]; 
517 
for (i = 0; i < AC3_MAX_COEFS; i++) { 
518 
int e;

519 
int v = abs(block>mdct_coef[ch][i]);

520 
if (v == 0) 
521 
e = 24;

522 
else {

523 
e = 23  av_log2(v) + block>exp_shift[ch];

524 
if (e >= 24) { 
525 
e = 24;

526 
block>mdct_coef[ch][i] = 0;

527 
} 
528 
} 
529 
block>exp[ch][i] = e; 
530 
} 
531 
} 
532 
} 
533 
} 
534  
535  
536 
/**

537 
* Exponent Difference Threshold.

538 
* New exponents are sent if their SAD exceed this number.

539 
*/

540 
#define EXP_DIFF_THRESHOLD 1000 
541  
542  
543 
/**

544 
* Calculate exponent strategies for all blocks in a single channel.

545 
*/

546 
static void compute_exp_strategy_ch(AC3EncodeContext *s, uint8_t *exp_strategy, uint8_t **exp) 
547 
{ 
548 
int blk, blk1;

549 
int exp_diff;

550  
551 
/* estimate if the exponent variation & decide if they should be

552 
reused in the next frame */

553 
exp_strategy[0] = EXP_NEW;

554 
for (blk = 1; blk < AC3_MAX_BLOCKS; blk++) { 
555 
exp_diff = s>dsp.sad[0](NULL, exp[blk], exp[blk1], 16, 16); 
556 
if (exp_diff > EXP_DIFF_THRESHOLD)

557 
exp_strategy[blk] = EXP_NEW; 
558 
else

559 
exp_strategy[blk] = EXP_REUSE; 
560 
} 
561  
562 
/* now select the encoding strategy type : if exponents are often

563 
recoded, we use a coarse encoding */

564 
blk = 0;

565 
while (blk < AC3_MAX_BLOCKS) {

566 
blk1 = blk + 1;

567 
while (blk1 < AC3_MAX_BLOCKS && exp_strategy[blk1] == EXP_REUSE)

568 
blk1++; 
569 
switch (blk1  blk) {

570 
case 1: exp_strategy[blk] = EXP_D45; break; 
571 
case 2: 
572 
case 3: exp_strategy[blk] = EXP_D25; break; 
573 
default: exp_strategy[blk] = EXP_D15; break; 
574 
} 
575 
blk = blk1; 
576 
} 
577 
} 
578  
579  
580 
/**

581 
* Calculate exponent strategies for all channels.

582 
* Array arrangement is reversed to simplify the perchannel calculation.

583 
*/

584 
static void compute_exp_strategy(AC3EncodeContext *s) 
585 
{ 
586 
uint8_t *exp1[AC3_MAX_CHANNELS][AC3_MAX_BLOCKS]; 
587 
uint8_t exp_str1[AC3_MAX_CHANNELS][AC3_MAX_BLOCKS]; 
588 
int ch, blk;

589  
590 
for (ch = 0; ch < s>fbw_channels; ch++) { 
591 
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) { 
592 
exp1[ch][blk] = s>blocks[blk].exp[ch]; 
593 
exp_str1[ch][blk] = s>blocks[blk].exp_strategy[ch]; 
594 
} 
595  
596 
compute_exp_strategy_ch(s, exp_str1[ch], exp1[ch]); 
597  
598 
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) 
599 
s>blocks[blk].exp_strategy[ch] = exp_str1[ch][blk]; 
600 
} 
601 
if (s>lfe_on) {

602 
ch = s>lfe_channel; 
603 
s>blocks[0].exp_strategy[ch] = EXP_D15;

604 
for (blk = 1; blk < AC3_MAX_BLOCKS; blk++) 
605 
s>blocks[blk].exp_strategy[ch] = EXP_REUSE; 
606 
} 
607 
} 
608  
609  
610 
/**

611 
* Set each encoded exponent in a block to the minimum of itself and the

612 
* exponent in the same frequency bin of a following block.

613 
* exp[i] = min(exp[i], exp1[i]

614 
*/

615 
static void exponent_min(uint8_t *exp, uint8_t *exp1, int n) 
616 
{ 
617 
int i;

618 
for (i = 0; i < n; i++) { 
619 
if (exp1[i] < exp[i])

620 
exp[i] = exp1[i]; 
621 
} 
622 
} 
623  
624  
625 
/**

626 
* Update the exponents so that they are the ones the decoder will decode.

627 
*/

628 
static void encode_exponents_blk_ch(uint8_t *exp, 
629 
int nb_exps, int exp_strategy) 
630 
{ 
631 
int nb_groups, i, k;

632  
633 
nb_groups = exponent_group_tab[exp_strategy1][nb_exps] * 3; 
634  
635 
/* for each group, compute the minimum exponent */

636 
switch(exp_strategy) {

637 
case EXP_D25:

638 
for (i = 1, k = 1; i <= nb_groups; i++) { 
639 
uint8_t exp_min = exp[k]; 
640 
if (exp[k+1] < exp_min) 
641 
exp_min = exp[k+1];

642 
exp[i] = exp_min; 
643 
k += 2;

644 
} 
645 
break;

646 
case EXP_D45:

647 
for (i = 1, k = 1; i <= nb_groups; i++) { 
648 
uint8_t exp_min = exp[k]; 
649 
if (exp[k+1] < exp_min) 
650 
exp_min = exp[k+1];

651 
if (exp[k+2] < exp_min) 
652 
exp_min = exp[k+2];

653 
if (exp[k+3] < exp_min) 
654 
exp_min = exp[k+3];

655 
exp[i] = exp_min; 
656 
k += 4;

657 
} 
658 
break;

659 
} 
660  
661 
/* constraint for DC exponent */

662 
if (exp[0] > 15) 
663 
exp[0] = 15; 
664  
665 
/* decrease the delta between each groups to within 2 so that they can be

666 
differentially encoded */

667 
for (i = 1; i <= nb_groups; i++) 
668 
exp[i] = FFMIN(exp[i], exp[i1] + 2); 
669 
i; 
670 
while (i >= 0) 
671 
exp[i] = FFMIN(exp[i], exp[i+1] + 2); 
672  
673 
/* now we have the exponent values the decoder will see */

674 
switch (exp_strategy) {

675 
case EXP_D25:

676 
for (i = nb_groups, k = nb_groups * 2; i > 0; i) { 
677 
uint8_t exp1 = exp[i]; 
678 
exp[k] = exp1; 
679 
exp[k] = exp1; 
680 
} 
681 
break;

682 
case EXP_D45:

683 
for (i = nb_groups, k = nb_groups * 4; i > 0; i) { 
684 
exp[k] = exp[k1] = exp[k2] = exp[k3] = exp[i]; 
685 
k = 4;

686 
} 
687 
break;

688 
} 
689 
} 
690  
691  
692 
/**

693 
* Encode exponents from original extracted form to what the decoder will see.

694 
* This copies and groups exponents based on exponent strategy and reduces

695 
* deltas between adjacent exponent groups so that they can be differentially

696 
* encoded.

697 
*/

698 
static void encode_exponents(AC3EncodeContext *s) 
699 
{ 
700 
int blk, blk1, blk2, ch;

701 
AC3Block *block, *block1, *block2; 
702  
703 
for (ch = 0; ch < s>channels; ch++) { 
704 
blk = 0;

705 
block = &s>blocks[0];

706 
while (blk < AC3_MAX_BLOCKS) {

707 
blk1 = blk + 1;

708 
block1 = block + 1;

709 
/* for the EXP_REUSE case we select the min of the exponents */

710 
while (blk1 < AC3_MAX_BLOCKS && block1>exp_strategy[ch] == EXP_REUSE) {

711 
exponent_min(block>exp[ch], block1>exp[ch], s>nb_coefs[ch]); 
712 
blk1++; 
713 
block1++; 
714 
} 
715 
encode_exponents_blk_ch(block>exp[ch], s>nb_coefs[ch], 
716 
block>exp_strategy[ch]); 
717 
/* copy encoded exponents for reuse case */

718 
block2 = block + 1;

719 
for (blk2 = blk+1; blk2 < blk1; blk2++, block2++) { 
720 
memcpy(block2>exp[ch], block>exp[ch], 
721 
s>nb_coefs[ch] * sizeof(uint8_t));

722 
} 
723 
blk = blk1; 
724 
block = block1; 
725 
} 
726 
} 
727 
} 
728  
729  
730 
/**

731 
* Group exponents.

732 
* 3 deltaencoded exponents are in each 7bit group. The number of groups

733 
* varies depending on exponent strategy and bandwidth.

734 
*/

735 
static void group_exponents(AC3EncodeContext *s) 
736 
{ 
737 
int blk, ch, i;

738 
int group_size, nb_groups, bit_count;

739 
uint8_t *p; 
740 
int delta0, delta1, delta2;

741 
int exp0, exp1;

742  
743 
bit_count = 0;

744 
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) { 
745 
AC3Block *block = &s>blocks[blk]; 
746 
for (ch = 0; ch < s>channels; ch++) { 
747 
if (block>exp_strategy[ch] == EXP_REUSE) {

748 
continue;

749 
} 
750 
group_size = block>exp_strategy[ch] + (block>exp_strategy[ch] == EXP_D45); 
751 
nb_groups = exponent_group_tab[block>exp_strategy[ch]1][s>nb_coefs[ch]];

752 
bit_count += 4 + (nb_groups * 7); 
753 
p = block>exp[ch]; 
754  
755 
/* DC exponent */

756 
exp1 = *p++; 
757 
block>grouped_exp[ch][0] = exp1;

758  
759 
/* remaining exponents are delta encoded */

760 
for (i = 1; i <= nb_groups; i++) { 
761 
/* merge three delta in one code */

762 
exp0 = exp1; 
763 
exp1 = p[0];

764 
p += group_size; 
765 
delta0 = exp1  exp0 + 2;

766  
767 
exp0 = exp1; 
768 
exp1 = p[0];

769 
p += group_size; 
770 
delta1 = exp1  exp0 + 2;

771  
772 
exp0 = exp1; 
773 
exp1 = p[0];

774 
p += group_size; 
775 
delta2 = exp1  exp0 + 2;

776  
777 
block>grouped_exp[ch][i] = ((delta0 * 5 + delta1) * 5) + delta2; 
778 
} 
779 
} 
780 
} 
781  
782 
s>exponent_bits = bit_count; 
783 
} 
784  
785  
786 
/**

787 
* Calculate final exponents from the supplied MDCT coefficients and exponent shift.

788 
* Extract exponents from MDCT coefficients, calculate exponent strategies,

789 
* and encode final exponents.

790 
*/

791 
static void process_exponents(AC3EncodeContext *s) 
792 
{ 
793 
extract_exponents(s); 
794  
795 
compute_exp_strategy(s); 
796  
797 
encode_exponents(s); 
798  
799 
group_exponents(s); 
800 
} 
801  
802  
803 
/**

804 
* Initialize bit allocation.

805 
* Set default parameter codes and calculate parameter values.

806 
*/

807 
static void bit_alloc_init(AC3EncodeContext *s) 
808 
{ 
809 
int ch;

810  
811 
/* init default parameters */

812 
s>slow_decay_code = 2;

813 
s>fast_decay_code = 1;

814 
s>slow_gain_code = 1;

815 
s>db_per_bit_code = 2;

816 
s>floor_code = 4;

817 
for (ch = 0; ch < s>channels; ch++) 
818 
s>fast_gain_code[ch] = 4;

819  
820 
/* initial snr offset */

821 
s>coarse_snr_offset = 40;

822  
823 
/* compute real values */

824 
/* currently none of these values change during encoding, so we can just

825 
set them once at initialization */

826 
s>bit_alloc.slow_decay = ff_ac3_slow_decay_tab[s>slow_decay_code] >> s>bit_alloc.sr_shift; 
827 
s>bit_alloc.fast_decay = ff_ac3_fast_decay_tab[s>fast_decay_code] >> s>bit_alloc.sr_shift; 
828 
s>bit_alloc.slow_gain = ff_ac3_slow_gain_tab[s>slow_gain_code]; 
829 
s>bit_alloc.db_per_bit = ff_ac3_db_per_bit_tab[s>db_per_bit_code]; 
830 
s>bit_alloc.floor = ff_ac3_floor_tab[s>floor_code]; 
831 
} 
832  
833  
834 
/**

835 
* Count the bits used to encode the frame, minus exponents and mantissas.

836 
*/

837 
static void count_frame_bits(AC3EncodeContext *s) 
838 
{ 
839 
static const int frame_bits_inc[8] = { 0, 0, 2, 2, 2, 4, 2, 4 }; 
840 
int blk, ch;

841 
int frame_bits;

842  
843 
/* header size */

844 
frame_bits = 65;

845 
frame_bits += frame_bits_inc[s>channel_mode]; 
846  
847 
/* audio blocks */

848 
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) { 
849 
frame_bits += s>fbw_channels * 2 + 2; /* blksw * c, dithflag * c, dynrnge, cplstre */ 
850 
if (s>channel_mode == AC3_CHMODE_STEREO) {

851 
frame_bits++; /* rematstr */

852 
if (!blk)

853 
frame_bits += 4;

854 
} 
855 
frame_bits += 2 * s>fbw_channels; /* chexpstr[2] * c */ 
856 
if (s>lfe_on)

857 
frame_bits++; /* lfeexpstr */

858 
for (ch = 0; ch < s>fbw_channels; ch++) { 
859 
if (s>blocks[blk].exp_strategy[ch] != EXP_REUSE)

860 
frame_bits += 6 + 2; /* chbwcod[6], gainrng[2] */ 
861 
} 
862 
frame_bits++; /* baie */

863 
frame_bits++; /* snr */

864 
frame_bits += 2; /* delta / skip */ 
865 
} 
866 
frame_bits++; /* cplinu for block 0 */

867 
/* bit alloc info */

868 
/* sdcycod[2], fdcycod[2], sgaincod[2], dbpbcod[2], floorcod[3] */

869 
/* csnroffset[6] */

870 
/* (fsnoffset[4] + fgaincod[4]) * c */

871 
frame_bits += 2*4 + 3 + 6 + s>channels * (4 + 3); 
872  
873 
/* auxdatae, crcrsv */

874 
frame_bits += 2;

875  
876 
/* CRC */

877 
frame_bits += 16;

878  
879 
s>frame_bits = frame_bits; 
880 
} 
881  
882  
883 
/**

884 
* Calculate the number of bits needed to encode a set of mantissas.

885 
*/

886 
static int compute_mantissa_size(AC3EncodeContext *s, uint8_t *bap, int nb_coefs) 
887 
{ 
888 
int bits, b, i;

889  
890 
bits = 0;

891 
for (i = 0; i < nb_coefs; i++) { 
892 
b = bap[i]; 
893 
switch (b) {

894 
case 0: 
895 
/* bap=0 mantissas are not encoded */

896 
break;

897 
case 1: 
898 
/* 3 mantissas in 5 bits */

899 
if (s>mant1_cnt == 0) 
900 
bits += 5;

901 
if (++s>mant1_cnt == 3) 
902 
s>mant1_cnt = 0;

903 
break;

904 
case 2: 
905 
/* 3 mantissas in 7 bits */

906 
if (s>mant2_cnt == 0) 
907 
bits += 7;

908 
if (++s>mant2_cnt == 3) 
909 
s>mant2_cnt = 0;

910 
break;

911 
case 3: 
912 
bits += 3;

913 
break;

914 
case 4: 
915 
/* 2 mantissas in 7 bits */

916 
if (s>mant4_cnt == 0) 
917 
bits += 7;

918 
if (++s>mant4_cnt == 2) 
919 
s>mant4_cnt = 0;

920 
break;

921 
case 14: 
922 
bits += 14;

923 
break;

924 
case 15: 
925 
bits += 16;

926 
break;

927 
default:

928 
bits += b  1;

929 
break;

930 
} 
931 
} 
932 
return bits;

933 
} 
934  
935  
936 
/**

937 
* Calculate masking curve based on the final exponents.

938 
* Also calculate the power spectral densities to use in future calculations.

939 
*/

940 
static void bit_alloc_masking(AC3EncodeContext *s) 
941 
{ 
942 
int blk, ch;

943  
944 
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) { 
945 
AC3Block *block = &s>blocks[blk]; 
946 
for (ch = 0; ch < s>channels; ch++) { 
947 
if (block>exp_strategy[ch] == EXP_REUSE) {

948 
AC3Block *block1 = &s>blocks[blk1];

949 
memcpy(block>psd[ch], block1>psd[ch], AC3_MAX_COEFS*sizeof(block>psd[0][0])); 
950 
memcpy(block>mask[ch], block1>mask[ch], AC3_CRITICAL_BANDS*sizeof(block>mask[0][0])); 
951 
} else {

952 
ff_ac3_bit_alloc_calc_psd(block>exp[ch], 0,

953 
s>nb_coefs[ch], 
954 
block>psd[ch], block>band_psd[ch]); 
955 
ff_ac3_bit_alloc_calc_mask(&s>bit_alloc, block>band_psd[ch], 
956 
0, s>nb_coefs[ch],

957 
ff_ac3_fast_gain_tab[s>fast_gain_code[ch]], 
958 
ch == s>lfe_channel, 
959 
DBA_NONE, 0, NULL, NULL, NULL, 
960 
block>mask[ch]); 
961 
} 
962 
} 
963 
} 
964 
} 
965  
966  
967 
/**

968 
* Ensure that bap for each block and channel point to the current bap_buffer.

969 
* They may have been switched during the bit allocation search.

970 
*/

971 
static void reset_block_bap(AC3EncodeContext *s) 
972 
{ 
973 
int blk, ch;

974 
if (s>blocks[0].bap[0] == s>bap_buffer) 
975 
return;

976 
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) { 
977 
for (ch = 0; ch < s>channels; ch++) { 
978 
s>blocks[blk].bap[ch] = &s>bap_buffer[AC3_MAX_COEFS * (blk * s>channels + ch)]; 
979 
} 
980 
} 
981 
} 
982  
983  
984 
/**

985 
* Run the bit allocation with a given SNR offset.

986 
* This calculates the bit allocation pointers that will be used to determine

987 
* the quantization of each mantissa.

988 
* @return the number of bits needed for mantissas if the given SNR offset is

989 
* is used.

990 
*/

991 
static int bit_alloc(AC3EncodeContext *s, 
992 
int snr_offset)

993 
{ 
994 
int blk, ch;

995 
int mantissa_bits;

996  
997 
snr_offset = (snr_offset  240) << 2; 
998  
999 
reset_block_bap(s); 
1000 
mantissa_bits = 0;

1001 
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) { 
1002 
AC3Block *block = &s>blocks[blk]; 
1003 
s>mant1_cnt = 0;

1004 
s>mant2_cnt = 0;

1005 
s>mant4_cnt = 0;

1006 
for (ch = 0; ch < s>channels; ch++) { 
1007 
ff_ac3_bit_alloc_calc_bap(block>mask[ch], block>psd[ch], 0,

1008 
s>nb_coefs[ch], snr_offset, 
1009 
s>bit_alloc.floor, ff_ac3_bap_tab, 
1010 
block>bap[ch]); 
1011 
mantissa_bits += compute_mantissa_size(s, block>bap[ch], s>nb_coefs[ch]); 
1012 
} 
1013 
} 
1014 
return mantissa_bits;

1015 
} 
1016  
1017  
1018 
/**

1019 
* Constant bitrate bit allocation search.

1020 
* Find the largest SNR offset that will allow data to fit in the frame.

1021 
*/

1022 
static int cbr_bit_allocation(AC3EncodeContext *s) 
1023 
{ 
1024 
int ch;

1025 
int bits_left;

1026 
int snr_offset;

1027  
1028 
bits_left = 8 * s>frame_size  (s>frame_bits + s>exponent_bits);

1029  
1030 
snr_offset = s>coarse_snr_offset << 4;

1031  
1032 
while (snr_offset >= 0 && 
1033 
bit_alloc(s, snr_offset) > bits_left) { 
1034 
snr_offset = 64;

1035 
} 
1036 
if (snr_offset < 0) 
1037 
return AVERROR(EINVAL);

1038  
1039 
FFSWAP(uint8_t *, s>bap_buffer, s>bap1_buffer); 
1040 
while (snr_offset + 64 <= 1023 && 
1041 
bit_alloc(s, snr_offset + 64) <= bits_left) {

1042 
snr_offset += 64;

1043 
FFSWAP(uint8_t *, s>bap_buffer, s>bap1_buffer); 
1044 
} 
1045 
while (snr_offset + 16 <= 1023 && 
1046 
bit_alloc(s, snr_offset + 16) <= bits_left) {

1047 
snr_offset += 16;

1048 
FFSWAP(uint8_t *, s>bap_buffer, s>bap1_buffer); 
1049 
} 
1050 
while (snr_offset + 4 <= 1023 && 
1051 
bit_alloc(s, snr_offset + 4) <= bits_left) {

1052 
snr_offset += 4;

1053 
FFSWAP(uint8_t *, s>bap_buffer, s>bap1_buffer); 
1054 
} 
1055 
while (snr_offset + 1 <= 1023 && 
1056 
bit_alloc(s, snr_offset + 1) <= bits_left) {

1057 
snr_offset++; 
1058 
FFSWAP(uint8_t *, s>bap_buffer, s>bap1_buffer); 
1059 
} 
1060 
FFSWAP(uint8_t *, s>bap_buffer, s>bap1_buffer); 
1061 
reset_block_bap(s); 
1062  
1063 
s>coarse_snr_offset = snr_offset >> 4;

1064 
for (ch = 0; ch < s>channels; ch++) 
1065 
s>fine_snr_offset[ch] = snr_offset & 0xF;

1066  
1067 
return 0; 
1068 
} 
1069  
1070  
1071 
/**

1072 
* Perform bit allocation search.

1073 
* Finds the SNR offset value that maximizes quality and fits in the specified

1074 
* frame size. Output is the SNR offset and a set of bit allocation pointers

1075 
* used to quantize the mantissas.

1076 
*/

1077 
static int compute_bit_allocation(AC3EncodeContext *s) 
1078 
{ 
1079 
count_frame_bits(s); 
1080  
1081 
bit_alloc_masking(s); 
1082  
1083 
return cbr_bit_allocation(s);

1084 
} 
1085  
1086  
1087 
/**

1088 
* Symmetric quantization on 'levels' levels.

1089 
*/

1090 
static inline int sym_quant(int c, int e, int levels) 
1091 
{ 
1092 
int v;

1093  
1094 
if (c >= 0) { 
1095 
v = (levels * (c << e)) >> 24;

1096 
v = (v + 1) >> 1; 
1097 
v = (levels >> 1) + v;

1098 
} else {

1099 
v = (levels * ((c) << e)) >> 24;

1100 
v = (v + 1) >> 1; 
1101 
v = (levels >> 1)  v;

1102 
} 
1103 
assert(v >= 0 && v < levels);

1104 
return v;

1105 
} 
1106  
1107  
1108 
/**

1109 
* Asymmetric quantization on 2^qbits levels.

1110 
*/

1111 
static inline int asym_quant(int c, int e, int qbits) 
1112 
{ 
1113 
int lshift, m, v;

1114  
1115 
lshift = e + qbits  24;

1116 
if (lshift >= 0) 
1117 
v = c << lshift; 
1118 
else

1119 
v = c >> (lshift); 
1120 
/* rounding */

1121 
v = (v + 1) >> 1; 
1122 
m = (1 << (qbits1)); 
1123 
if (v >= m)

1124 
v = m  1;

1125 
assert(v >= m); 
1126 
return v & ((1 << qbits)1); 
1127 
} 
1128  
1129  
1130 
/**

1131 
* Quantize a set of mantissas for a single channel in a single block.

1132 
*/

1133 
static void quantize_mantissas_blk_ch(AC3EncodeContext *s, 
1134 
int32_t *mdct_coef, int8_t exp_shift, 
1135 
uint8_t *exp, uint8_t *bap, 
1136 
uint16_t *qmant, int n)

1137 
{ 
1138 
int i;

1139  
1140 
for (i = 0; i < n; i++) { 
1141 
int v;

1142 
int c = mdct_coef[i];

1143 
int e = exp[i]  exp_shift;

1144 
int b = bap[i];

1145 
switch (b) {

1146 
case 0: 
1147 
v = 0;

1148 
break;

1149 
case 1: 
1150 
v = sym_quant(c, e, 3);

1151 
switch (s>mant1_cnt) {

1152 
case 0: 
1153 
s>qmant1_ptr = &qmant[i]; 
1154 
v = 9 * v;

1155 
s>mant1_cnt = 1;

1156 
break;

1157 
case 1: 
1158 
*s>qmant1_ptr += 3 * v;

1159 
s>mant1_cnt = 2;

1160 
v = 128;

1161 
break;

1162 
default:

1163 
*s>qmant1_ptr += v; 
1164 
s>mant1_cnt = 0;

1165 
v = 128;

1166 
break;

1167 
} 
1168 
break;

1169 
case 2: 
1170 
v = sym_quant(c, e, 5);

1171 
switch (s>mant2_cnt) {

1172 
case 0: 
1173 
s>qmant2_ptr = &qmant[i]; 
1174 
v = 25 * v;

1175 
s>mant2_cnt = 1;

1176 
break;

1177 
case 1: 
1178 
*s>qmant2_ptr += 5 * v;

1179 
s>mant2_cnt = 2;

1180 
v = 128;

1181 
break;

1182 
default:

1183 
*s>qmant2_ptr += v; 
1184 
s>mant2_cnt = 0;

1185 
v = 128;

1186 
break;

1187 
} 
1188 
break;

1189 
case 3: 
1190 
v = sym_quant(c, e, 7);

1191 
break;

1192 
case 4: 
1193 
v = sym_quant(c, e, 11);

1194 
switch (s>mant4_cnt) {

1195 
case 0: 
1196 
s>qmant4_ptr = &qmant[i]; 
1197 
v = 11 * v;

1198 
s>mant4_cnt = 1;

1199 
break;

1200 
default:

1201 
*s>qmant4_ptr += v; 
1202 
s>mant4_cnt = 0;

1203 
v = 128;

1204 
break;

1205 
} 
1206 
break;

1207 
case 5: 
1208 
v = sym_quant(c, e, 15);

1209 
break;

1210 
case 14: 
1211 
v = asym_quant(c, e, 14);

1212 
break;

1213 
case 15: 
1214 
v = asym_quant(c, e, 16);

1215 
break;

1216 
default:

1217 
v = asym_quant(c, e, b  1);

1218 
break;

1219 
} 
1220 
qmant[i] = v; 
1221 
} 
1222 
} 
1223  
1224  
1225 
/**

1226 
* Quantize mantissas using coefficients, exponents, and bit allocation pointers.

1227 
*/

1228 
static void quantize_mantissas(AC3EncodeContext *s) 
1229 
{ 
1230 
int blk, ch;

1231  
1232  
1233 
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) { 
1234 
AC3Block *block = &s>blocks[blk]; 
1235 
s>mant1_cnt = s>mant2_cnt = s>mant4_cnt = 0;

1236 
s>qmant1_ptr = s>qmant2_ptr = s>qmant4_ptr = NULL;

1237  
1238 
for (ch = 0; ch < s>channels; ch++) { 
1239 
quantize_mantissas_blk_ch(s, block>mdct_coef[ch], block>exp_shift[ch], 
1240 
block>exp[ch], block>bap[ch], 
1241 
block>qmant[ch], s>nb_coefs[ch]); 
1242 
} 
1243 
} 
1244 
} 
1245  
1246  
1247 
/**

1248 
* Write the AC3 frame header to the output bitstream.

1249 
*/

1250 
static void output_frame_header(AC3EncodeContext *s) 
1251 
{ 
1252 
put_bits(&s>pb, 16, 0x0b77); /* frame header */ 
1253 
put_bits(&s>pb, 16, 0); /* crc1: will be filled later */ 
1254 
put_bits(&s>pb, 2, s>bit_alloc.sr_code);

1255 
put_bits(&s>pb, 6, s>frame_size_code + (s>frame_size  s>frame_size_min) / 2); 
1256 
put_bits(&s>pb, 5, s>bitstream_id);

1257 
put_bits(&s>pb, 3, s>bitstream_mode);

1258 
put_bits(&s>pb, 3, s>channel_mode);

1259 
if ((s>channel_mode & 0x01) && s>channel_mode != AC3_CHMODE_MONO) 
1260 
put_bits(&s>pb, 2, 1); /* XXX 4.5 dB */ 
1261 
if (s>channel_mode & 0x04) 
1262 
put_bits(&s>pb, 2, 1); /* XXX 6 dB */ 
1263 
if (s>channel_mode == AC3_CHMODE_STEREO)

1264 
put_bits(&s>pb, 2, 0); /* surround not indicated */ 
1265 
put_bits(&s>pb, 1, s>lfe_on); /* LFE */ 
1266 
put_bits(&s>pb, 5, 31); /* dialog norm: 31 db */ 
1267 
put_bits(&s>pb, 1, 0); /* no compression control word */ 
1268 
put_bits(&s>pb, 1, 0); /* no lang code */ 
1269 
put_bits(&s>pb, 1, 0); /* no audio production info */ 
1270 
put_bits(&s>pb, 1, 0); /* no copyright */ 
1271 
put_bits(&s>pb, 1, 1); /* original bitstream */ 
1272 
put_bits(&s>pb, 1, 0); /* no time code 1 */ 
1273 
put_bits(&s>pb, 1, 0); /* no time code 2 */ 
1274 
put_bits(&s>pb, 1, 0); /* no additional bit stream info */ 
1275 
} 
1276  
1277  
1278 
/**

1279 
* Write one audio block to the output bitstream.

1280 
*/

1281 
static void output_audio_block(AC3EncodeContext *s, 
1282 
int block_num)

1283 
{ 
1284 
int ch, i, baie, rbnd;

1285 
AC3Block *block = &s>blocks[block_num]; 
1286  
1287 
/* block switching */

1288 
for (ch = 0; ch < s>fbw_channels; ch++) 
1289 
put_bits(&s>pb, 1, 0); 
1290  
1291 
/* dither flags */

1292 
for (ch = 0; ch < s>fbw_channels; ch++) 
1293 
put_bits(&s>pb, 1, 1); 
1294  
1295 
/* dynamic range codes */

1296 
put_bits(&s>pb, 1, 0); 
1297  
1298 
/* channel coupling */

1299 
if (!block_num) {

1300 
put_bits(&s>pb, 1, 1); /* coupling strategy present */ 
1301 
put_bits(&s>pb, 1, 0); /* no coupling strategy */ 
1302 
} else {

1303 
put_bits(&s>pb, 1, 0); /* no new coupling strategy */ 
1304 
} 
1305  
1306 
/* stereo rematrixing */

1307 
if (s>channel_mode == AC3_CHMODE_STEREO) {

1308 
if (!block_num) {

1309 
/* first block must define rematrixing (rematstr) */

1310 
put_bits(&s>pb, 1, 1); 
1311  
1312 
/* dummy rematrixing rematflg(1:4)=0 */

1313 
for (rbnd = 0; rbnd < 4; rbnd++) 
1314 
put_bits(&s>pb, 1, 0); 
1315 
} else {

1316 
/* no matrixing (but should be used in the future) */

1317 
put_bits(&s>pb, 1, 0); 
1318 
} 
1319 
} 
1320  
1321 
/* exponent strategy */

1322 
for (ch = 0; ch < s>fbw_channels; ch++) 
1323 
put_bits(&s>pb, 2, block>exp_strategy[ch]);

1324 
if (s>lfe_on)

1325 
put_bits(&s>pb, 1, block>exp_strategy[s>lfe_channel]);

1326  
1327 
/* bandwidth */

1328 
for (ch = 0; ch < s>fbw_channels; ch++) { 
1329 
if (block>exp_strategy[ch] != EXP_REUSE)

1330 
put_bits(&s>pb, 6, s>bandwidth_code[ch]);

1331 
} 
1332  
1333 
/* exponents */

1334 
for (ch = 0; ch < s>channels; ch++) { 
1335 
int nb_groups;

1336  
1337 
if (block>exp_strategy[ch] == EXP_REUSE)

1338 
continue;

1339  
1340 
/* DC exponent */

1341 
put_bits(&s>pb, 4, block>grouped_exp[ch][0]); 
1342  
1343 
/* exponent groups */

1344 
nb_groups = exponent_group_tab[block>exp_strategy[ch]1][s>nb_coefs[ch]];

1345 
for (i = 1; i <= nb_groups; i++) 
1346 
put_bits(&s>pb, 7, block>grouped_exp[ch][i]);

1347  
1348 
/* gain range info */

1349 
if (ch != s>lfe_channel)

1350 
put_bits(&s>pb, 2, 0); 
1351 
} 
1352  
1353 
/* bit allocation info */

1354 
baie = (block_num == 0);

1355 
put_bits(&s>pb, 1, baie);

1356 
if (baie) {

1357 
put_bits(&s>pb, 2, s>slow_decay_code);

1358 
put_bits(&s>pb, 2, s>fast_decay_code);

1359 
put_bits(&s>pb, 2, s>slow_gain_code);

1360 
put_bits(&s>pb, 2, s>db_per_bit_code);

1361 
put_bits(&s>pb, 3, s>floor_code);

1362 
} 
1363  
1364 
/* snr offset */

1365 
put_bits(&s>pb, 1, baie);

1366 
if (baie) {

1367 
put_bits(&s>pb, 6, s>coarse_snr_offset);

1368 
for (ch = 0; ch < s>channels; ch++) { 
1369 
put_bits(&s>pb, 4, s>fine_snr_offset[ch]);

1370 
put_bits(&s>pb, 3, s>fast_gain_code[ch]);

1371 
} 
1372 
} 
1373  
1374 
put_bits(&s>pb, 1, 0); /* no delta bit allocation */ 
1375 
put_bits(&s>pb, 1, 0); /* no data to skip */ 
1376  
1377 
/* mantissas */

1378 
for (ch = 0; ch < s>channels; ch++) { 
1379 
int b, q;

1380 
for (i = 0; i < s>nb_coefs[ch]; i++) { 
1381 
q = block>qmant[ch][i]; 
1382 
b = block>bap[ch][i]; 
1383 
switch (b) {

1384 
case 0: break; 
1385 
case 1: if (q != 128) put_bits(&s>pb, 5, q); break; 
1386 
case 2: if (q != 128) put_bits(&s>pb, 7, q); break; 
1387 
case 3: put_bits(&s>pb, 3, q); break; 
1388 
case 4: if (q != 128) put_bits(&s>pb, 7, q); break; 
1389 
case 14: put_bits(&s>pb, 14, q); break; 
1390 
case 15: put_bits(&s>pb, 16, q); break; 
1391 
default: put_bits(&s>pb, b1, q); break; 
1392 
} 
1393 
} 
1394 
} 
1395 
} 
1396  
1397  
1398 
/** CRC16 Polynomial */

1399 
#define CRC16_POLY ((1 << 0)  (1 << 2)  (1 << 15)  (1 << 16)) 
1400  
1401  
1402 
static unsigned int mul_poly(unsigned int a, unsigned int b, unsigned int poly) 
1403 
{ 
1404 
unsigned int c; 
1405  
1406 
c = 0;

1407 
while (a) {

1408 
if (a & 1) 
1409 
c ^= b; 
1410 
a = a >> 1;

1411 
b = b << 1;

1412 
if (b & (1 << 16)) 
1413 
b ^= poly; 
1414 
} 
1415 
return c;

1416 
} 
1417  
1418  
1419 
static unsigned int pow_poly(unsigned int a, unsigned int n, unsigned int poly) 
1420 
{ 
1421 
unsigned int r; 
1422 
r = 1;

1423 
while (n) {

1424 
if (n & 1) 
1425 
r = mul_poly(r, a, poly); 
1426 
a = mul_poly(a, a, poly); 
1427 
n >>= 1;

1428 
} 
1429 
return r;

1430 
} 
1431  
1432  
1433 
/**

1434 
* Fill the end of the frame with 0's and compute the two CRCs.

1435 
*/

1436 
static void output_frame_end(AC3EncodeContext *s) 
1437 
{ 
1438 
int frame_size, frame_size_58, pad_bytes, crc1, crc2, crc_inv;

1439 
uint8_t *frame; 
1440  
1441 
frame_size = s>frame_size; 
1442 
frame_size_58 = ((frame_size >> 2) + (frame_size >> 4)) << 1; 
1443  
1444 
/* pad the remainder of the frame with zeros */

1445 
flush_put_bits(&s>pb); 
1446 
frame = s>pb.buf; 
1447 
pad_bytes = s>frame_size  (put_bits_ptr(&s>pb)  frame)  2;

1448 
assert(pad_bytes >= 0);

1449 
if (pad_bytes > 0) 
1450 
memset(put_bits_ptr(&s>pb), 0, pad_bytes);

1451  
1452 
/* compute crc1 */

1453 
/* this is not so easy because it is at the beginning of the data... */

1454 
crc1 = av_bswap16(av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0,

1455 
frame + 4, frame_size_58  4)); 
1456 
/* XXX: could precompute crc_inv */

1457 
crc_inv = pow_poly((CRC16_POLY >> 1), (8 * frame_size_58)  16, CRC16_POLY); 
1458 
crc1 = mul_poly(crc_inv, crc1, CRC16_POLY); 
1459 
AV_WB16(frame + 2, crc1);

1460  
1461 
/* compute crc2 */

1462 
crc2 = av_bswap16(av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0,

1463 
frame + frame_size_58, 
1464 
frame_size  frame_size_58  2));

1465 
AV_WB16(frame + frame_size  2, crc2);

1466 
} 
1467  
1468  
1469 
/**

1470 
* Write the frame to the output bitstream.

1471 
*/

1472 
static void output_frame(AC3EncodeContext *s, 
1473 
unsigned char *frame) 
1474 
{ 
1475 
int blk;

1476  
1477 
init_put_bits(&s>pb, frame, AC3_MAX_CODED_FRAME_SIZE); 
1478  
1479 
output_frame_header(s); 
1480  
1481 
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) 
1482 
output_audio_block(s, blk); 
1483  
1484 
output_frame_end(s); 
1485 
} 
1486  
1487  
1488 
/**

1489 
* Encode a single AC3 frame.

1490 
*/

1491 
static int ac3_encode_frame(AVCodecContext *avctx, 
1492 
unsigned char *frame, int buf_size, void *data) 
1493 
{ 
1494 
AC3EncodeContext *s = avctx>priv_data; 
1495 
const int16_t *samples = data;

1496 
int ret;

1497  
1498 
if (s>bit_alloc.sr_code == 1) 
1499 
adjust_frame_size(s); 
1500  
1501 
deinterleave_input_samples(s, samples); 
1502  
1503 
apply_mdct(s); 
1504  
1505 
process_exponents(s); 
1506  
1507 
ret = compute_bit_allocation(s); 
1508 
if (ret) {

1509 
av_log(avctx, AV_LOG_ERROR, "Bit allocation failed. Try increasing the bitrate.\n");

1510 
return ret;

1511 
} 
1512  
1513 
quantize_mantissas(s); 
1514  
1515 
output_frame(s, frame); 
1516  
1517 
return s>frame_size;

1518 
} 
1519  
1520  
1521 
/**

1522 
* Finalize encoding and free any memory allocated by the encoder.

1523 
*/

1524 
static av_cold int ac3_encode_close(AVCodecContext *avctx) 
1525 
{ 
1526 
int blk, ch;

1527 
AC3EncodeContext *s = avctx>priv_data; 
1528  
1529 
for (ch = 0; ch < s>channels; ch++) 
1530 
av_freep(&s>planar_samples[ch]); 
1531 
av_freep(&s>planar_samples); 
1532 
av_freep(&s>bap_buffer); 
1533 
av_freep(&s>bap1_buffer); 
1534 
av_freep(&s>mdct_coef_buffer); 
1535 
av_freep(&s>exp_buffer); 
1536 
av_freep(&s>grouped_exp_buffer); 
1537 
av_freep(&s>psd_buffer); 
1538 
av_freep(&s>band_psd_buffer); 
1539 
av_freep(&s>mask_buffer); 
1540 
av_freep(&s>qmant_buffer); 
1541 
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) { 
1542 
AC3Block *block = &s>blocks[blk]; 
1543 
av_freep(&block>bap); 
1544 
av_freep(&block>mdct_coef); 
1545 
av_freep(&block>exp); 
1546 
av_freep(&block>grouped_exp); 
1547 
av_freep(&block>psd); 
1548 
av_freep(&block>band_psd); 
1549 
av_freep(&block>mask); 
1550 
av_freep(&block>qmant); 
1551 
} 
1552  
1553 
mdct_end(&s>mdct); 
1554  
1555 
av_freep(&avctx>coded_frame); 
1556 
return 0; 
1557 
} 
1558  
1559  
1560 
/**

1561 
* Set channel information during initialization.

1562 
*/

1563 
static av_cold int set_channel_info(AC3EncodeContext *s, int channels, 
1564 
int64_t *channel_layout) 
1565 
{ 
1566 
int ch_layout;

1567  
1568 
if (channels < 1  channels > AC3_MAX_CHANNELS) 
1569 
return AVERROR(EINVAL);

1570 
if ((uint64_t)*channel_layout > 0x7FF) 
1571 
return AVERROR(EINVAL);

1572 
ch_layout = *channel_layout; 
1573 
if (!ch_layout)

1574 
ch_layout = avcodec_guess_channel_layout(channels, CODEC_ID_AC3, NULL);

1575 
if (av_get_channel_layout_nb_channels(ch_layout) != channels)

1576 
return AVERROR(EINVAL);

1577  
1578 
s>lfe_on = !!(ch_layout & AV_CH_LOW_FREQUENCY); 
1579 
s>channels = channels; 
1580 
s>fbw_channels = channels  s>lfe_on; 
1581 
s>lfe_channel = s>lfe_on ? s>fbw_channels : 1;

1582 
if (s>lfe_on)

1583 
ch_layout = AV_CH_LOW_FREQUENCY; 
1584  
1585 
switch (ch_layout) {

1586 
case AV_CH_LAYOUT_MONO: s>channel_mode = AC3_CHMODE_MONO; break; 
1587 
case AV_CH_LAYOUT_STEREO: s>channel_mode = AC3_CHMODE_STEREO; break; 
1588 
case AV_CH_LAYOUT_SURROUND: s>channel_mode = AC3_CHMODE_3F; break; 
1589 
case AV_CH_LAYOUT_2_1: s>channel_mode = AC3_CHMODE_2F1R; break; 
1590 
case AV_CH_LAYOUT_4POINT0: s>channel_mode = AC3_CHMODE_3F1R; break; 
1591 
case AV_CH_LAYOUT_QUAD:

1592 
case AV_CH_LAYOUT_2_2: s>channel_mode = AC3_CHMODE_2F2R; break; 
1593 
case AV_CH_LAYOUT_5POINT0:

1594 
case AV_CH_LAYOUT_5POINT0_BACK: s>channel_mode = AC3_CHMODE_3F2R; break; 
1595 
default:

1596 
return AVERROR(EINVAL);

1597 
} 
1598  
1599 
s>channel_map = ff_ac3_enc_channel_map[s>channel_mode][s>lfe_on]; 
1600 
*channel_layout = ch_layout; 
1601 
if (s>lfe_on)

1602 
*channel_layout = AV_CH_LOW_FREQUENCY; 
1603  
1604 
return 0; 
1605 
} 
1606  
1607  
1608 
static av_cold int validate_options(AVCodecContext *avctx, AC3EncodeContext *s) 
1609 
{ 
1610 
int i, ret;

1611  
1612 
/* validate channel layout */

1613 
if (!avctx>channel_layout) {

1614 
av_log(avctx, AV_LOG_WARNING, "No channel layout specified. The "

1615 
"encoder will guess the layout, but it "

1616 
"might be incorrect.\n");

1617 
} 
1618 
ret = set_channel_info(s, avctx>channels, &avctx>channel_layout); 
1619 
if (ret) {

1620 
av_log(avctx, AV_LOG_ERROR, "invalid channel layout\n");

1621 
return ret;

1622 
} 
1623  
1624 
/* validate sample rate */

1625 
for (i = 0; i < 9; i++) { 
1626 
if ((ff_ac3_sample_rate_tab[i / 3] >> (i % 3)) == avctx>sample_rate) 
1627 
break;

1628 
} 
1629 
if (i == 9) { 
1630 
av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n");

1631 
return AVERROR(EINVAL);

1632 
} 
1633 
s>sample_rate = avctx>sample_rate; 
1634 
s>bit_alloc.sr_shift = i % 3;

1635 
s>bit_alloc.sr_code = i / 3;

1636  
1637 
/* validate bit rate */

1638 
for (i = 0; i < 19; i++) { 
1639 
if ((ff_ac3_bitrate_tab[i] >> s>bit_alloc.sr_shift)*1000 == avctx>bit_rate) 
1640 
break;

1641 
} 
1642 
if (i == 19) { 
1643 
av_log(avctx, AV_LOG_ERROR, "invalid bit rate\n");

1644 
return AVERROR(EINVAL);

1645 
} 
1646 
s>bit_rate = avctx>bit_rate; 
1647 
s>frame_size_code = i << 1;

1648  
1649 
return 0; 
1650 
} 
1651  
1652  
1653 
/**

1654 
* Set bandwidth for all channels.

1655 
* The user can optionally supply a cutoff frequency. Otherwise an appropriate

1656 
* default value will be used.

1657 
*/

1658 
static av_cold void set_bandwidth(AC3EncodeContext *s, int cutoff) 
1659 
{ 
1660 
int ch, bw_code;

1661  
1662 
if (cutoff) {

1663 
/* calculate bandwidth based on userspecified cutoff frequency */

1664 
int fbw_coeffs;

1665 
cutoff = av_clip(cutoff, 1, s>sample_rate >> 1); 
1666 
fbw_coeffs = cutoff * 2 * AC3_MAX_COEFS / s>sample_rate;

1667 
bw_code = av_clip((fbw_coeffs  73) / 3, 0, 60); 
1668 
} else {

1669 
/* use default bandwidth setting */

1670 
/* XXX: should compute the bandwidth according to the frame

1671 
size, so that we avoid annoying high frequency artifacts */

1672 
bw_code = 50;

1673 
} 
1674  
1675 
/* set number of coefficients for each channel */

1676 
for (ch = 0; ch < s>fbw_channels; ch++) { 
1677 
s>bandwidth_code[ch] = bw_code; 
1678 
s>nb_coefs[ch] = bw_code * 3 + 73; 
1679 
} 
1680 
if (s>lfe_on)

1681 
s>nb_coefs[s>lfe_channel] = 7; /* LFE channel always has 7 coefs */ 
1682 
} 
1683  
1684  
1685 
static av_cold int allocate_buffers(AVCodecContext *avctx) 
1686 
{ 
1687 
int blk, ch;

1688 
AC3EncodeContext *s = avctx>priv_data; 
1689  
1690 
FF_ALLOC_OR_GOTO(avctx, s>planar_samples, s>channels * sizeof(*s>planar_samples),

1691 
alloc_fail); 
1692 
for (ch = 0; ch < s>channels; ch++) { 
1693 
FF_ALLOCZ_OR_GOTO(avctx, s>planar_samples[ch], 
1694 
(AC3_FRAME_SIZE+AC3_BLOCK_SIZE) * sizeof(**s>planar_samples),

1695 
alloc_fail); 
1696 
} 
1697 
FF_ALLOC_OR_GOTO(avctx, s>bap_buffer, AC3_MAX_BLOCKS * s>channels * 
1698 
AC3_MAX_COEFS * sizeof(*s>bap_buffer), alloc_fail);

1699 
FF_ALLOC_OR_GOTO(avctx, s>bap1_buffer, AC3_MAX_BLOCKS * s>channels * 
1700 
AC3_MAX_COEFS * sizeof(*s>bap1_buffer), alloc_fail);

1701 
FF_ALLOC_OR_GOTO(avctx, s>mdct_coef_buffer, AC3_MAX_BLOCKS * s>channels * 
1702 
AC3_MAX_COEFS * sizeof(*s>mdct_coef_buffer), alloc_fail);

1703 
FF_ALLOC_OR_GOTO(avctx, s>exp_buffer, AC3_MAX_BLOCKS * s>channels * 
1704 
AC3_MAX_COEFS * sizeof(*s>exp_buffer), alloc_fail);

1705 
FF_ALLOC_OR_GOTO(avctx, s>grouped_exp_buffer, AC3_MAX_BLOCKS * s>channels * 
1706 
128 * sizeof(*s>grouped_exp_buffer), alloc_fail); 
1707 
FF_ALLOC_OR_GOTO(avctx, s>psd_buffer, AC3_MAX_BLOCKS * s>channels * 
1708 
AC3_MAX_COEFS * sizeof(*s>psd_buffer), alloc_fail);

1709 
FF_ALLOC_OR_GOTO(avctx, s>band_psd_buffer, AC3_MAX_BLOCKS * s>channels * 
1710 
64 * sizeof(*s>band_psd_buffer), alloc_fail); 
1711 
FF_ALLOC_OR_GOTO(avctx, s>mask_buffer, AC3_MAX_BLOCKS * s>channels * 
1712 
64 * sizeof(*s>mask_buffer), alloc_fail); 
1713 
FF_ALLOC_OR_GOTO(avctx, s>qmant_buffer, AC3_MAX_BLOCKS * s>channels * 
1714 
AC3_MAX_COEFS * sizeof(*s>qmant_buffer), alloc_fail);

1715 
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) { 
1716 
AC3Block *block = &s>blocks[blk]; 
1717 
FF_ALLOC_OR_GOTO(avctx, block>bap, s>channels * sizeof(*block>bap),

1718 
alloc_fail); 
1719 
FF_ALLOCZ_OR_GOTO(avctx, block>mdct_coef, s>channels * sizeof(*block>mdct_coef),

1720 
alloc_fail); 
1721 
FF_ALLOCZ_OR_GOTO(avctx, block>exp, s>channels * sizeof(*block>exp),

1722 
alloc_fail); 
1723 
FF_ALLOCZ_OR_GOTO(avctx, block>grouped_exp, s>channels * sizeof(*block>grouped_exp),

1724 
alloc_fail); 
1725 
FF_ALLOCZ_OR_GOTO(avctx, block>psd, s>channels * sizeof(*block>psd),

1726 
alloc_fail); 
1727 
FF_ALLOCZ_OR_GOTO(avctx, block>band_psd, s>channels * sizeof(*block>band_psd),

1728 
alloc_fail); 
1729 
FF_ALLOCZ_OR_GOTO(avctx, block>mask, s>channels * sizeof(*block>mask),

1730 
alloc_fail); 
1731 
FF_ALLOCZ_OR_GOTO(avctx, block>qmant, s>channels * sizeof(*block>qmant),

1732 
alloc_fail); 
1733  
1734 
for (ch = 0; ch < s>channels; ch++) { 
1735 
block>bap[ch] = &s>bap_buffer [AC3_MAX_COEFS * (blk * s>channels + ch)]; 
1736 
block>mdct_coef[ch] = &s>mdct_coef_buffer [AC3_MAX_COEFS * (blk * s>channels + ch)]; 
1737 
block>exp[ch] = &s>exp_buffer [AC3_MAX_COEFS * (blk * s>channels + ch)]; 
1738 
block>grouped_exp[ch] = &s>grouped_exp_buffer[128 * (blk * s>channels + ch)];

1739 
block>psd[ch] = &s>psd_buffer [AC3_MAX_COEFS * (blk * s>channels + ch)]; 
1740 
block>band_psd[ch] = &s>band_psd_buffer [64 * (blk * s>channels + ch)];

1741 
block>mask[ch] = &s>mask_buffer [64 * (blk * s>channels + ch)];

1742 
block>qmant[ch] = &s>qmant_buffer [AC3_MAX_COEFS * (blk * s>channels + ch)]; 
1743 
} 
1744 
} 
1745  
1746 
return 0; 
1747 
alloc_fail:

1748 
return AVERROR(ENOMEM);

1749 
} 
1750  
1751  
1752 
/**

1753 
* Initialize the encoder.

1754 
*/

1755 
static av_cold int ac3_encode_init(AVCodecContext *avctx) 
1756 
{ 
1757 
AC3EncodeContext *s = avctx>priv_data; 
1758 
int ret;

1759  
1760 
avctx>frame_size = AC3_FRAME_SIZE; 
1761  
1762 
ac3_common_init(); 
1763  
1764 
ret = validate_options(avctx, s); 
1765 
if (ret)

1766 
return ret;

1767  
1768 
s>bitstream_id = 8 + s>bit_alloc.sr_shift;

1769 
s>bitstream_mode = 0; /* complete main audio service */ 
1770  
1771 
s>frame_size_min = 2 * ff_ac3_frame_size_tab[s>frame_size_code][s>bit_alloc.sr_code];

1772 
s>bits_written = 0;

1773 
s>samples_written = 0;

1774 
s>frame_size = s>frame_size_min; 
1775  
1776 
set_bandwidth(s, avctx>cutoff); 
1777  
1778 
exponent_init(s); 
1779  
1780 
bit_alloc_init(s); 
1781  
1782 
s>mdct.avctx = avctx; 
1783 
ret = mdct_init(&s>mdct, 9);

1784 
if (ret)

1785 
goto init_fail;

1786  
1787 
ret = allocate_buffers(avctx); 
1788 
if (ret)

1789 
goto init_fail;

1790  
1791 
avctx>coded_frame= avcodec_alloc_frame(); 
1792  
1793 
dsputil_init(&s>dsp, avctx); 
1794  
1795 
return 0; 
1796 
init_fail:

1797 
ac3_encode_close(avctx); 
1798 
return ret;

1799 
} 
1800  
1801  
1802 
#ifdef TEST

1803 
/*************************************************************************/

1804 
/* TEST */

1805  
1806 
#include "libavutil/lfg.h" 
1807  
1808 
#define FN (MDCT_SAMPLES/4) 
1809  
1810  
1811 
static void fft_test(AVLFG *lfg) 
1812 
{ 
1813 
IComplex in[FN], in1[FN]; 
1814 
int k, n, i;

1815 
float sum_re, sum_im, a;

1816  
1817 
for (i = 0; i < FN; i++) { 
1818 
in[i].re = av_lfg_get(lfg) % 65535  32767; 
1819 
in[i].im = av_lfg_get(lfg) % 65535  32767; 
1820 
in1[i] = in[i]; 
1821 
} 
1822 
fft(in, 7);

1823  
1824 
/* do it by hand */

1825 
for (k = 0; k < FN; k++) { 
1826 
sum_re = 0;

1827 
sum_im = 0;

1828 
for (n = 0; n < FN; n++) { 
1829 
a = 2 * M_PI * (n * k) / FN;

1830 
sum_re += in1[n].re * cos(a)  in1[n].im * sin(a); 
1831 
sum_im += in1[n].re * sin(a) + in1[n].im * cos(a); 
1832 
} 
1833 
av_log(NULL, AV_LOG_DEBUG, "%3d: %6d,%6d %6.0f,%6.0f\n", 
1834 
k, in[k].re, in[k].im, sum_re / FN, sum_im / FN); 
1835 
} 
1836 
} 
1837  
1838  
1839 
static void mdct_test(AVLFG *lfg) 
1840 
{ 
1841 
int16_t input[MDCT_SAMPLES]; 
1842 
int32_t output[AC3_MAX_COEFS]; 
1843 
float input1[MDCT_SAMPLES];

1844 
float output1[AC3_MAX_COEFS];

1845 
float s, a, err, e, emax;

1846 
int i, k, n;

1847  
1848 
for (i = 0; i < MDCT_SAMPLES; i++) { 
1849 
input[i] = (av_lfg_get(lfg) % 65535  32767) * 9 / 10; 
1850 
input1[i] = input[i]; 
1851 
} 
1852  
1853 
mdct512(output, input); 
1854  
1855 
/* do it by hand */

1856 
for (k = 0; k < AC3_MAX_COEFS; k++) { 
1857 
s = 0;

1858 
for (n = 0; n < MDCT_SAMPLES; n++) { 
1859 
a = (2*M_PI*(2*n+1+MDCT_SAMPLES/2)*(2*k+1) / (4 * MDCT_SAMPLES)); 
1860 
s += input1[n] * cos(a); 
1861 
} 
1862 
output1[k] = 2 * s / MDCT_SAMPLES;

1863 
} 
1864  
1865 
err = 0;

1866 
emax = 0;

1867 
for (i = 0; i < AC3_MAX_COEFS; i++) { 
1868 
av_log(NULL, AV_LOG_DEBUG, "%3d: %7d %7.0f\n", i, output[i], output1[i]); 
1869 
e = output[i]  output1[i]; 
1870 
if (e > emax)

1871 
emax = e; 
1872 
err += e * e; 
1873 
} 
1874 
av_log(NULL, AV_LOG_DEBUG, "err2=%f emax=%f\n", err / AC3_MAX_COEFS, emax); 
1875 
} 
1876  
1877  
1878 
int main(void) 
1879 
{ 
1880 
AVLFG lfg; 
1881  
1882 
av_log_set_level(AV_LOG_DEBUG); 
1883 
mdct_init(9);

1884  
1885 
fft_test(&lfg); 
1886 
mdct_test(&lfg); 
1887  
1888 
return 0; 
1889 
} 
1890 
#endif /* TEST */ 
1891  
1892  
1893 
AVCodec ac3_encoder = { 
1894 
"ac3",

1895 
AVMEDIA_TYPE_AUDIO, 
1896 
CODEC_ID_AC3, 
1897 
sizeof(AC3EncodeContext),

1898 
ac3_encode_init, 
1899 
ac3_encode_frame, 
1900 
ac3_encode_close, 
1901 
NULL,

1902 
.sample_fmts = (const enum AVSampleFormat[]){AV_SAMPLE_FMT_S16,AV_SAMPLE_FMT_NONE}, 
1903 
.long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC3)"),

1904 
.channel_layouts = (const int64_t[]){

1905 
AV_CH_LAYOUT_MONO, 
1906 
AV_CH_LAYOUT_STEREO, 
1907 
AV_CH_LAYOUT_2_1, 
1908 
AV_CH_LAYOUT_SURROUND, 
1909 
AV_CH_LAYOUT_2_2, 
1910 
AV_CH_LAYOUT_QUAD, 
1911 
AV_CH_LAYOUT_4POINT0, 
1912 
AV_CH_LAYOUT_5POINT0, 
1913 
AV_CH_LAYOUT_5POINT0_BACK, 
1914 
(AV_CH_LAYOUT_MONO  AV_CH_LOW_FREQUENCY), 
1915 
(AV_CH_LAYOUT_STEREO  AV_CH_LOW_FREQUENCY), 
1916 
(AV_CH_LAYOUT_2_1  AV_CH_LOW_FREQUENCY), 
1917 
(AV_CH_LAYOUT_SURROUND  AV_CH_LOW_FREQUENCY), 
1918 
(AV_CH_LAYOUT_2_2  AV_CH_LOW_FREQUENCY), 
1919 
(AV_CH_LAYOUT_QUAD  AV_CH_LOW_FREQUENCY), 
1920 
(AV_CH_LAYOUT_4POINT0  AV_CH_LOW_FREQUENCY), 
1921 
AV_CH_LAYOUT_5POINT1, 
1922 
AV_CH_LAYOUT_5POINT1_BACK, 
1923 
0 },

1924 
}; 