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1
/*
2
 * The simplest AC3 encoder
3
 * Copyright (c) 2000 Fabrice Bellard.
4
 *
5
 * This file is part of FFmpeg.
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 *
7
 * FFmpeg is free software; you can redistribute it and/or
8
 * modify it under the terms of the GNU Lesser General Public
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 * License as published by the Free Software Foundation; either
10
 * version 2.1 of the License, or (at your option) any later version.
11
 *
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 * FFmpeg is distributed in the hope that it will be useful,
13
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
15
 * 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 02110-1301 USA
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 */
21

    
22
/**
23
 * @file ac3enc.c
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 * The simplest AC3 encoder.
25
 */
26
//#define DEBUG
27
//#define DEBUG_BITALLOC
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#include "avcodec.h"
29
#include "bitstream.h"
30
#include "crc.h"
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#include "ac3.h"
32

    
33
typedef struct AC3EncodeContext {
34
    PutBitContext pb;
35
    int nb_channels;
36
    int nb_all_channels;
37
    int lfe_channel;
38
    int bit_rate;
39
    unsigned int sample_rate;
40
    unsigned int bitstream_id;
41
    unsigned int frame_size_min; /* minimum frame size in case rounding is necessary */
42
    unsigned int frame_size; /* current frame size in words */
43
    unsigned int bits_written;
44
    unsigned int samples_written;
45
    int sr_shift;
46
    unsigned int frame_size_code;
47
    unsigned int sr_code; /* frequency */
48
    unsigned int channel_mode;
49
    int lfe;
50
    unsigned int bitstream_mode;
51
    short last_samples[AC3_MAX_CHANNELS][256];
52
    unsigned int chbwcod[AC3_MAX_CHANNELS];
53
    int nb_coefs[AC3_MAX_CHANNELS];
54

    
55
    /* bitrate allocation control */
56
    int slow_gain_code, slow_decay_code, fast_decay_code, db_per_bit_code, floor_code;
57
    AC3BitAllocParameters bit_alloc;
58
    int coarse_snr_offset;
59
    int fast_gain_code[AC3_MAX_CHANNELS];
60
    int fine_snr_offset[AC3_MAX_CHANNELS];
61
    /* mantissa encoding */
62
    int mant1_cnt, mant2_cnt, mant4_cnt;
63
} AC3EncodeContext;
64

    
65
static int16_t costab[64];
66
static int16_t sintab[64];
67
static int16_t xcos1[128];
68
static int16_t xsin1[128];
69

    
70
#define MDCT_NBITS 9
71
#define N         (1 << MDCT_NBITS)
72

    
73
/* new exponents are sent if their Norm 1 exceed this number */
74
#define EXP_DIFF_THRESHOLD 1000
75

    
76
static void fft_init(int ln);
77

    
78
static inline int16_t fix15(float a)
79
{
80
    int v;
81
    v = (int)(a * (float)(1 << 15));
82
    if (v < -32767)
83
        v = -32767;
84
    else if (v > 32767)
85
        v = 32767;
86
    return v;
87
}
88

    
89
typedef struct IComplex {
90
    short re,im;
91
} IComplex;
92

    
93
static void fft_init(int ln)
94
{
95
    int i, j, m, n;
96
    float alpha;
97

    
98
    n = 1 << ln;
99

    
100
    for(i=0;i<(n/2);i++) {
101
        alpha = 2 * M_PI * (float)i / (float)n;
102
        costab[i] = fix15(cos(alpha));
103
        sintab[i] = fix15(sin(alpha));
104
    }
105
}
106

    
107
/* butter fly op */
108
#define BF(pre, pim, qre, qim, pre1, pim1, qre1, qim1) \
109
{\
110
  int ax, ay, bx, by;\
111
  bx=pre1;\
112
  by=pim1;\
113
  ax=qre1;\
114
  ay=qim1;\
115
  pre = (bx + ax) >> 1;\
116
  pim = (by + ay) >> 1;\
117
  qre = (bx - ax) >> 1;\
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  qim = (by - ay) >> 1;\
119
}
120

    
121
#define MUL16(a,b) ((a) * (b))
122

    
123
#define CMUL(pre, pim, are, aim, bre, bim) \
124
{\
125
   pre = (MUL16(are, bre) - MUL16(aim, bim)) >> 15;\
126
   pim = (MUL16(are, bim) + MUL16(bre, aim)) >> 15;\
127
}
128

    
129

    
130
/* do a 2^n point complex fft on 2^ln points. */
131
static void fft(IComplex *z, int ln)
132
{
133
    int        j, l, np, np2;
134
    int        nblocks, nloops;
135
    register IComplex *p,*q;
136
    int tmp_re, tmp_im;
137

    
138
    np = 1 << ln;
139

    
140
    /* reverse */
141
    for(j=0;j<np;j++) {
142
        int k = ff_reverse[j] >> (8 - ln);
143
        if (k < j)
144
            FFSWAP(IComplex, z[k], z[j]);
145
    }
146

    
147
    /* pass 0 */
148

    
149
    p=&z[0];
150
    j=(np >> 1);
151
    do {
152
        BF(p[0].re, p[0].im, p[1].re, p[1].im,
153
           p[0].re, p[0].im, p[1].re, p[1].im);
154
        p+=2;
155
    } while (--j != 0);
156

    
157
    /* pass 1 */
158

    
159
    p=&z[0];
160
    j=np >> 2;
161
    do {
162
        BF(p[0].re, p[0].im, p[2].re, p[2].im,
163
           p[0].re, p[0].im, p[2].re, p[2].im);
164
        BF(p[1].re, p[1].im, p[3].re, p[3].im,
165
           p[1].re, p[1].im, p[3].im, -p[3].re);
166
        p+=4;
167
    } while (--j != 0);
168

    
169
    /* pass 2 .. ln-1 */
170

    
171
    nblocks = np >> 3;
172
    nloops = 1 << 2;
173
    np2 = np >> 1;
174
    do {
175
        p = z;
176
        q = z + nloops;
177
        for (j = 0; j < nblocks; ++j) {
178

    
179
            BF(p->re, p->im, q->re, q->im,
180
               p->re, p->im, q->re, q->im);
181

    
182
            p++;
183
            q++;
184
            for(l = nblocks; l < np2; l += nblocks) {
185
                CMUL(tmp_re, tmp_im, costab[l], -sintab[l], q->re, q->im);
186
                BF(p->re, p->im, q->re, q->im,
187
                   p->re, p->im, tmp_re, tmp_im);
188
                p++;
189
                q++;
190
            }
191
            p += nloops;
192
            q += nloops;
193
        }
194
        nblocks = nblocks >> 1;
195
        nloops = nloops << 1;
196
    } while (nblocks != 0);
197
}
198

    
199
/* do a 512 point mdct */
200
static void mdct512(int32_t *out, int16_t *in)
201
{
202
    int i, re, im, re1, im1;
203
    int16_t rot[N];
204
    IComplex x[N/4];
205

    
206
    /* shift to simplify computations */
207
    for(i=0;i<N/4;i++)
208
        rot[i] = -in[i + 3*N/4];
209
    for(i=N/4;i<N;i++)
210
        rot[i] = in[i - N/4];
211

    
212
    /* pre rotation */
213
    for(i=0;i<N/4;i++) {
214
        re = ((int)rot[2*i] - (int)rot[N-1-2*i]) >> 1;
215
        im = -((int)rot[N/2+2*i] - (int)rot[N/2-1-2*i]) >> 1;
216
        CMUL(x[i].re, x[i].im, re, im, -xcos1[i], xsin1[i]);
217
    }
218

    
219
    fft(x, MDCT_NBITS - 2);
220

    
221
    /* post rotation */
222
    for(i=0;i<N/4;i++) {
223
        re = x[i].re;
224
        im = x[i].im;
225
        CMUL(re1, im1, re, im, xsin1[i], xcos1[i]);
226
        out[2*i] = im1;
227
        out[N/2-1-2*i] = re1;
228
    }
229
}
230

    
231
/* XXX: use another norm ? */
232
static int calc_exp_diff(uint8_t *exp1, uint8_t *exp2, int n)
233
{
234
    int sum, i;
235
    sum = 0;
236
    for(i=0;i<n;i++) {
237
        sum += abs(exp1[i] - exp2[i]);
238
    }
239
    return sum;
240
}
241

    
242
static void compute_exp_strategy(uint8_t exp_strategy[NB_BLOCKS][AC3_MAX_CHANNELS],
243
                                 uint8_t exp[NB_BLOCKS][AC3_MAX_CHANNELS][N/2],
244
                                 int ch, int is_lfe)
245
{
246
    int i, j;
247
    int exp_diff;
248

    
249
    /* estimate if the exponent variation & decide if they should be
250
       reused in the next frame */
251
    exp_strategy[0][ch] = EXP_NEW;
252
    for(i=1;i<NB_BLOCKS;i++) {
253
        exp_diff = calc_exp_diff(exp[i][ch], exp[i-1][ch], N/2);
254
#ifdef DEBUG
255
        av_log(NULL, AV_LOG_DEBUG, "exp_diff=%d\n", exp_diff);
256
#endif
257
        if (exp_diff > EXP_DIFF_THRESHOLD)
258
            exp_strategy[i][ch] = EXP_NEW;
259
        else
260
            exp_strategy[i][ch] = EXP_REUSE;
261
    }
262
    if (is_lfe)
263
        return;
264

    
265
    /* now select the encoding strategy type : if exponents are often
266
       recoded, we use a coarse encoding */
267
    i = 0;
268
    while (i < NB_BLOCKS) {
269
        j = i + 1;
270
        while (j < NB_BLOCKS && exp_strategy[j][ch] == EXP_REUSE)
271
            j++;
272
        switch(j - i) {
273
        case 1:
274
            exp_strategy[i][ch] = EXP_D45;
275
            break;
276
        case 2:
277
        case 3:
278
            exp_strategy[i][ch] = EXP_D25;
279
            break;
280
        default:
281
            exp_strategy[i][ch] = EXP_D15;
282
            break;
283
        }
284
        i = j;
285
    }
286
}
287

    
288
/* set exp[i] to min(exp[i], exp1[i]) */
289
static void exponent_min(uint8_t exp[N/2], uint8_t exp1[N/2], int n)
290
{
291
    int i;
292

    
293
    for(i=0;i<n;i++) {
294
        if (exp1[i] < exp[i])
295
            exp[i] = exp1[i];
296
    }
297
}
298

    
299
/* update the exponents so that they are the ones the decoder will
300
   decode. Return the number of bits used to code the exponents */
301
static int encode_exp(uint8_t encoded_exp[N/2],
302
                      uint8_t exp[N/2],
303
                      int nb_exps,
304
                      int exp_strategy)
305
{
306
    int group_size, nb_groups, i, j, k, exp_min;
307
    uint8_t exp1[N/2];
308

    
309
    switch(exp_strategy) {
310
    case EXP_D15:
311
        group_size = 1;
312
        break;
313
    case EXP_D25:
314
        group_size = 2;
315
        break;
316
    default:
317
    case EXP_D45:
318
        group_size = 4;
319
        break;
320
    }
321
    nb_groups = ((nb_exps + (group_size * 3) - 4) / (3 * group_size)) * 3;
322

    
323
    /* for each group, compute the minimum exponent */
324
    exp1[0] = exp[0]; /* DC exponent is handled separately */
325
    k = 1;
326
    for(i=1;i<=nb_groups;i++) {
327
        exp_min = exp[k];
328
        assert(exp_min >= 0 && exp_min <= 24);
329
        for(j=1;j<group_size;j++) {
330
            if (exp[k+j] < exp_min)
331
                exp_min = exp[k+j];
332
        }
333
        exp1[i] = exp_min;
334
        k += group_size;
335
    }
336

    
337
    /* constraint for DC exponent */
338
    if (exp1[0] > 15)
339
        exp1[0] = 15;
340

    
341
    /* Decrease the delta between each groups to within 2
342
     * so that they can be differentially encoded */
343
    for (i=1;i<=nb_groups;i++)
344
        exp1[i] = FFMIN(exp1[i], exp1[i-1] + 2);
345
    for (i=nb_groups-1;i>=0;i--)
346
        exp1[i] = FFMIN(exp1[i], exp1[i+1] + 2);
347

    
348
    /* now we have the exponent values the decoder will see */
349
    encoded_exp[0] = exp1[0];
350
    k = 1;
351
    for(i=1;i<=nb_groups;i++) {
352
        for(j=0;j<group_size;j++) {
353
            encoded_exp[k+j] = exp1[i];
354
        }
355
        k += group_size;
356
    }
357

    
358
#if defined(DEBUG)
359
    av_log(NULL, AV_LOG_DEBUG, "exponents: strategy=%d\n", exp_strategy);
360
    for(i=0;i<=nb_groups * group_size;i++) {
361
        av_log(NULL, AV_LOG_DEBUG, "%d ", encoded_exp[i]);
362
    }
363
    av_log(NULL, AV_LOG_DEBUG, "\n");
364
#endif
365

    
366
    return 4 + (nb_groups / 3) * 7;
367
}
368

    
369
/* return the size in bits taken by the mantissa */
370
static int compute_mantissa_size(AC3EncodeContext *s, uint8_t *m, int nb_coefs)
371
{
372
    int bits, mant, i;
373

    
374
    bits = 0;
375
    for(i=0;i<nb_coefs;i++) {
376
        mant = m[i];
377
        switch(mant) {
378
        case 0:
379
            /* nothing */
380
            break;
381
        case 1:
382
            /* 3 mantissa in 5 bits */
383
            if (s->mant1_cnt == 0)
384
                bits += 5;
385
            if (++s->mant1_cnt == 3)
386
                s->mant1_cnt = 0;
387
            break;
388
        case 2:
389
            /* 3 mantissa in 7 bits */
390
            if (s->mant2_cnt == 0)
391
                bits += 7;
392
            if (++s->mant2_cnt == 3)
393
                s->mant2_cnt = 0;
394
            break;
395
        case 3:
396
            bits += 3;
397
            break;
398
        case 4:
399
            /* 2 mantissa in 7 bits */
400
            if (s->mant4_cnt == 0)
401
                bits += 7;
402
            if (++s->mant4_cnt == 2)
403
                s->mant4_cnt = 0;
404
            break;
405
        case 14:
406
            bits += 14;
407
            break;
408
        case 15:
409
            bits += 16;
410
            break;
411
        default:
412
            bits += mant - 1;
413
            break;
414
        }
415
    }
416
    return bits;
417
}
418

    
419

    
420
static void bit_alloc_masking(AC3EncodeContext *s,
421
                              uint8_t encoded_exp[NB_BLOCKS][AC3_MAX_CHANNELS][N/2],
422
                              uint8_t exp_strategy[NB_BLOCKS][AC3_MAX_CHANNELS],
423
                              int16_t psd[NB_BLOCKS][AC3_MAX_CHANNELS][N/2],
424
                              int16_t mask[NB_BLOCKS][AC3_MAX_CHANNELS][50])
425
{
426
    int blk, ch;
427
    int16_t band_psd[NB_BLOCKS][AC3_MAX_CHANNELS][50];
428

    
429
    for(blk=0; blk<NB_BLOCKS; blk++) {
430
        for(ch=0;ch<s->nb_all_channels;ch++) {
431
            if(exp_strategy[blk][ch] == EXP_REUSE) {
432
                memcpy(psd[blk][ch], psd[blk-1][ch], (N/2)*sizeof(int16_t));
433
                memcpy(mask[blk][ch], mask[blk-1][ch], 50*sizeof(int16_t));
434
            } else {
435
                ff_ac3_bit_alloc_calc_psd(encoded_exp[blk][ch], 0,
436
                                          s->nb_coefs[ch],
437
                                          psd[blk][ch], band_psd[blk][ch]);
438
                ff_ac3_bit_alloc_calc_mask(&s->bit_alloc, band_psd[blk][ch],
439
                                           0, s->nb_coefs[ch],
440
                                           ff_ac3_fast_gain_tab[s->fast_gain_code[ch]],
441
                                           ch == s->lfe_channel,
442
                                           DBA_NONE, 0, NULL, NULL, NULL,
443
                                           mask[blk][ch]);
444
            }
445
        }
446
    }
447
}
448

    
449
static int bit_alloc(AC3EncodeContext *s,
450
                     int16_t mask[NB_BLOCKS][AC3_MAX_CHANNELS][50],
451
                     int16_t psd[NB_BLOCKS][AC3_MAX_CHANNELS][N/2],
452
                     uint8_t bap[NB_BLOCKS][AC3_MAX_CHANNELS][N/2],
453
                     int frame_bits, int coarse_snr_offset, int fine_snr_offset)
454
{
455
    int i, ch;
456
    int snr_offset;
457

    
458
    snr_offset = (((coarse_snr_offset - 15) << 4) + fine_snr_offset) << 2;
459

    
460
    /* compute size */
461
    for(i=0;i<NB_BLOCKS;i++) {
462
        s->mant1_cnt = 0;
463
        s->mant2_cnt = 0;
464
        s->mant4_cnt = 0;
465
        for(ch=0;ch<s->nb_all_channels;ch++) {
466
            ff_ac3_bit_alloc_calc_bap(mask[i][ch], psd[i][ch], 0,
467
                                      s->nb_coefs[ch], snr_offset,
468
                                      s->bit_alloc.floor, bap[i][ch]);
469
            frame_bits += compute_mantissa_size(s, bap[i][ch],
470
                                                 s->nb_coefs[ch]);
471
        }
472
    }
473
#if 0
474
    printf("csnr=%d fsnr=%d frame_bits=%d diff=%d\n",
475
           coarse_snr_offset, fine_snr_offset, frame_bits,
476
           16 * s->frame_size - ((frame_bits + 7) & ~7));
477
#endif
478
    return 16 * s->frame_size - frame_bits;
479
}
480

    
481
#define SNR_INC1 4
482

    
483
static int compute_bit_allocation(AC3EncodeContext *s,
484
                                  uint8_t bap[NB_BLOCKS][AC3_MAX_CHANNELS][N/2],
485
                                  uint8_t encoded_exp[NB_BLOCKS][AC3_MAX_CHANNELS][N/2],
486
                                  uint8_t exp_strategy[NB_BLOCKS][AC3_MAX_CHANNELS],
487
                                  int frame_bits)
488
{
489
    int i, ch;
490
    int coarse_snr_offset, fine_snr_offset;
491
    uint8_t bap1[NB_BLOCKS][AC3_MAX_CHANNELS][N/2];
492
    int16_t psd[NB_BLOCKS][AC3_MAX_CHANNELS][N/2];
493
    int16_t mask[NB_BLOCKS][AC3_MAX_CHANNELS][50];
494
    static int frame_bits_inc[8] = { 0, 0, 2, 2, 2, 4, 2, 4 };
495

    
496
    /* init default parameters */
497
    s->slow_decay_code = 2;
498
    s->fast_decay_code = 1;
499
    s->slow_gain_code = 1;
500
    s->db_per_bit_code = 2;
501
    s->floor_code = 4;
502
    for(ch=0;ch<s->nb_all_channels;ch++)
503
        s->fast_gain_code[ch] = 4;
504

    
505
    /* compute real values */
506
    s->bit_alloc.sr_code = s->sr_code;
507
    s->bit_alloc.sr_shift = s->sr_shift;
508
    s->bit_alloc.slow_decay = ff_ac3_slow_decay_tab[s->slow_decay_code] >> s->sr_shift;
509
    s->bit_alloc.fast_decay = ff_ac3_fast_decay_tab[s->fast_decay_code] >> s->sr_shift;
510
    s->bit_alloc.slow_gain = ff_ac3_slow_gain_tab[s->slow_gain_code];
511
    s->bit_alloc.db_per_bit = ff_ac3_db_per_bit_tab[s->db_per_bit_code];
512
    s->bit_alloc.floor = ff_ac3_floor_tab[s->floor_code];
513

    
514
    /* header size */
515
    frame_bits += 65;
516
    // if (s->channel_mode == 2)
517
    //    frame_bits += 2;
518
    frame_bits += frame_bits_inc[s->channel_mode];
519

    
520
    /* audio blocks */
521
    for(i=0;i<NB_BLOCKS;i++) {
522
        frame_bits += s->nb_channels * 2 + 2; /* blksw * c, dithflag * c, dynrnge, cplstre */
523
        if (s->channel_mode == AC3_CHMODE_STEREO) {
524
            frame_bits++; /* rematstr */
525
            if(i==0) frame_bits += 4;
526
        }
527
        frame_bits += 2 * s->nb_channels; /* chexpstr[2] * c */
528
        if (s->lfe)
529
            frame_bits++; /* lfeexpstr */
530
        for(ch=0;ch<s->nb_channels;ch++) {
531
            if (exp_strategy[i][ch] != EXP_REUSE)
532
                frame_bits += 6 + 2; /* chbwcod[6], gainrng[2] */
533
        }
534
        frame_bits++; /* baie */
535
        frame_bits++; /* snr */
536
        frame_bits += 2; /* delta / skip */
537
    }
538
    frame_bits++; /* cplinu for block 0 */
539
    /* bit alloc info */
540
    /* sdcycod[2], fdcycod[2], sgaincod[2], dbpbcod[2], floorcod[3] */
541
    /* csnroffset[6] */
542
    /* (fsnoffset[4] + fgaincod[4]) * c */
543
    frame_bits += 2*4 + 3 + 6 + s->nb_all_channels * (4 + 3);
544

    
545
    /* auxdatae, crcrsv */
546
    frame_bits += 2;
547

    
548
    /* CRC */
549
    frame_bits += 16;
550

    
551
    /* calculate psd and masking curve before doing bit allocation */
552
    bit_alloc_masking(s, encoded_exp, exp_strategy, psd, mask);
553

    
554
    /* now the big work begins : do the bit allocation. Modify the snr
555
       offset until we can pack everything in the requested frame size */
556

    
557
    coarse_snr_offset = s->coarse_snr_offset;
558
    while (coarse_snr_offset >= 0 &&
559
           bit_alloc(s, mask, psd, bap, frame_bits, coarse_snr_offset, 0) < 0)
560
        coarse_snr_offset -= SNR_INC1;
561
    if (coarse_snr_offset < 0) {
562
        av_log(NULL, AV_LOG_ERROR, "Bit allocation failed. Try increasing the bitrate.\n");
563
        return -1;
564
    }
565
    while ((coarse_snr_offset + SNR_INC1) <= 63 &&
566
           bit_alloc(s, mask, psd, bap1, frame_bits,
567
                     coarse_snr_offset + SNR_INC1, 0) >= 0) {
568
        coarse_snr_offset += SNR_INC1;
569
        memcpy(bap, bap1, sizeof(bap1));
570
    }
571
    while ((coarse_snr_offset + 1) <= 63 &&
572
           bit_alloc(s, mask, psd, bap1, frame_bits, coarse_snr_offset + 1, 0) >= 0) {
573
        coarse_snr_offset++;
574
        memcpy(bap, bap1, sizeof(bap1));
575
    }
576

    
577
    fine_snr_offset = 0;
578
    while ((fine_snr_offset + SNR_INC1) <= 15 &&
579
           bit_alloc(s, mask, psd, bap1, frame_bits,
580
                     coarse_snr_offset, fine_snr_offset + SNR_INC1) >= 0) {
581
        fine_snr_offset += SNR_INC1;
582
        memcpy(bap, bap1, sizeof(bap1));
583
    }
584
    while ((fine_snr_offset + 1) <= 15 &&
585
           bit_alloc(s, mask, psd, bap1, frame_bits,
586
                     coarse_snr_offset, fine_snr_offset + 1) >= 0) {
587
        fine_snr_offset++;
588
        memcpy(bap, bap1, sizeof(bap1));
589
    }
590

    
591
    s->coarse_snr_offset = coarse_snr_offset;
592
    for(ch=0;ch<s->nb_all_channels;ch++)
593
        s->fine_snr_offset[ch] = fine_snr_offset;
594
#if defined(DEBUG_BITALLOC)
595
    {
596
        int j;
597

    
598
        for(i=0;i<6;i++) {
599
            for(ch=0;ch<s->nb_all_channels;ch++) {
600
                printf("Block #%d Ch%d:\n", i, ch);
601
                printf("bap=");
602
                for(j=0;j<s->nb_coefs[ch];j++) {
603
                    printf("%d ",bap[i][ch][j]);
604
                }
605
                printf("\n");
606
            }
607
        }
608
    }
609
#endif
610
    return 0;
611
}
612

    
613
static int AC3_encode_init(AVCodecContext *avctx)
614
{
615
    int freq = avctx->sample_rate;
616
    int bitrate = avctx->bit_rate;
617
    int channels = avctx->channels;
618
    AC3EncodeContext *s = avctx->priv_data;
619
    int i, j, ch;
620
    float alpha;
621
    int bw_code;
622
    static const uint8_t channel_mode_defs[6] = {
623
        0x01, /* C */
624
        0x02, /* L R */
625
        0x03, /* L C R */
626
        0x06, /* L R SL SR */
627
        0x07, /* L C R SL SR */
628
        0x07, /* L C R SL SR (+LFE) */
629
    };
630

    
631
    avctx->frame_size = AC3_FRAME_SIZE;
632

    
633
    ac3_common_init();
634

    
635
    /* number of channels */
636
    if (channels < 1 || channels > 6)
637
        return -1;
638
    s->channel_mode = channel_mode_defs[channels - 1];
639
    s->lfe = (channels == 6) ? 1 : 0;
640
    s->nb_all_channels = channels;
641
    s->nb_channels = channels > 5 ? 5 : channels;
642
    s->lfe_channel = s->lfe ? 5 : -1;
643

    
644
    /* frequency */
645
    for(i=0;i<3;i++) {
646
        for(j=0;j<3;j++)
647
            if ((ff_ac3_sample_rate_tab[j] >> i) == freq)
648
                goto found;
649
    }
650
    return -1;
651
 found:
652
    s->sample_rate = freq;
653
    s->sr_shift = i;
654
    s->sr_code = j;
655
    s->bitstream_id = 8 + s->sr_shift;
656
    s->bitstream_mode = 0; /* complete main audio service */
657

    
658
    /* bitrate & frame size */
659
    for(i=0;i<19;i++) {
660
        if ((ff_ac3_bitrate_tab[i] >> s->sr_shift)*1000 == bitrate)
661
            break;
662
    }
663
    if (i == 19)
664
        return -1;
665
    s->bit_rate = bitrate;
666
    s->frame_size_code = i << 1;
667
    s->frame_size_min = ff_ac3_frame_size_tab[s->frame_size_code][s->sr_code];
668
    s->bits_written = 0;
669
    s->samples_written = 0;
670
    s->frame_size = s->frame_size_min;
671

    
672
    /* bit allocation init */
673
    if(avctx->cutoff) {
674
        /* calculate bandwidth based on user-specified cutoff frequency */
675
        int cutoff = av_clip(avctx->cutoff, 1, s->sample_rate >> 1);
676
        int fbw_coeffs = cutoff * 512 / s->sample_rate;
677
        bw_code = av_clip((fbw_coeffs - 73) / 3, 0, 60);
678
    } else {
679
        /* use default bandwidth setting */
680
        /* XXX: should compute the bandwidth according to the frame
681
           size, so that we avoid anoying high freq artefacts */
682
        bw_code = 50;
683
    }
684
    for(ch=0;ch<s->nb_channels;ch++) {
685
        /* bandwidth for each channel */
686
        s->chbwcod[ch] = bw_code;
687
        s->nb_coefs[ch] = bw_code * 3 + 73;
688
    }
689
    if (s->lfe) {
690
        s->nb_coefs[s->lfe_channel] = 7; /* fixed */
691
    }
692
    /* initial snr offset */
693
    s->coarse_snr_offset = 40;
694

    
695
    /* mdct init */
696
    fft_init(MDCT_NBITS - 2);
697
    for(i=0;i<N/4;i++) {
698
        alpha = 2 * M_PI * (i + 1.0 / 8.0) / (float)N;
699
        xcos1[i] = fix15(-cos(alpha));
700
        xsin1[i] = fix15(-sin(alpha));
701
    }
702

    
703
    avctx->coded_frame= avcodec_alloc_frame();
704
    avctx->coded_frame->key_frame= 1;
705

    
706
    return 0;
707
}
708

    
709
/* output the AC3 frame header */
710
static void output_frame_header(AC3EncodeContext *s, unsigned char *frame)
711
{
712
    init_put_bits(&s->pb, frame, AC3_MAX_CODED_FRAME_SIZE);
713

    
714
    put_bits(&s->pb, 16, 0x0b77); /* frame header */
715
    put_bits(&s->pb, 16, 0); /* crc1: will be filled later */
716
    put_bits(&s->pb, 2, s->sr_code);
717
    put_bits(&s->pb, 6, s->frame_size_code + (s->frame_size - s->frame_size_min));
718
    put_bits(&s->pb, 5, s->bitstream_id);
719
    put_bits(&s->pb, 3, s->bitstream_mode);
720
    put_bits(&s->pb, 3, s->channel_mode);
721
    if ((s->channel_mode & 0x01) && s->channel_mode != AC3_CHMODE_MONO)
722
        put_bits(&s->pb, 2, 1); /* XXX -4.5 dB */
723
    if (s->channel_mode & 0x04)
724
        put_bits(&s->pb, 2, 1); /* XXX -6 dB */
725
    if (s->channel_mode == AC3_CHMODE_STEREO)
726
        put_bits(&s->pb, 2, 0); /* surround not indicated */
727
    put_bits(&s->pb, 1, s->lfe); /* LFE */
728
    put_bits(&s->pb, 5, 31); /* dialog norm: -31 db */
729
    put_bits(&s->pb, 1, 0); /* no compression control word */
730
    put_bits(&s->pb, 1, 0); /* no lang code */
731
    put_bits(&s->pb, 1, 0); /* no audio production info */
732
    put_bits(&s->pb, 1, 0); /* no copyright */
733
    put_bits(&s->pb, 1, 1); /* original bitstream */
734
    put_bits(&s->pb, 1, 0); /* no time code 1 */
735
    put_bits(&s->pb, 1, 0); /* no time code 2 */
736
    put_bits(&s->pb, 1, 0); /* no additional bit stream info */
737
}
738

    
739
/* symetric quantization on 'levels' levels */
740
static inline int sym_quant(int c, int e, int levels)
741
{
742
    int v;
743

    
744
    if (c >= 0) {
745
        v = (levels * (c << e)) >> 24;
746
        v = (v + 1) >> 1;
747
        v = (levels >> 1) + v;
748
    } else {
749
        v = (levels * ((-c) << e)) >> 24;
750
        v = (v + 1) >> 1;
751
        v = (levels >> 1) - v;
752
    }
753
    assert (v >= 0 && v < levels);
754
    return v;
755
}
756

    
757
/* asymetric quantization on 2^qbits levels */
758
static inline int asym_quant(int c, int e, int qbits)
759
{
760
    int lshift, m, v;
761

    
762
    lshift = e + qbits - 24;
763
    if (lshift >= 0)
764
        v = c << lshift;
765
    else
766
        v = c >> (-lshift);
767
    /* rounding */
768
    v = (v + 1) >> 1;
769
    m = (1 << (qbits-1));
770
    if (v >= m)
771
        v = m - 1;
772
    assert(v >= -m);
773
    return v & ((1 << qbits)-1);
774
}
775

    
776
/* Output one audio block. There are NB_BLOCKS audio blocks in one AC3
777
   frame */
778
static void output_audio_block(AC3EncodeContext *s,
779
                               uint8_t exp_strategy[AC3_MAX_CHANNELS],
780
                               uint8_t encoded_exp[AC3_MAX_CHANNELS][N/2],
781
                               uint8_t bap[AC3_MAX_CHANNELS][N/2],
782
                               int32_t mdct_coefs[AC3_MAX_CHANNELS][N/2],
783
                               int8_t global_exp[AC3_MAX_CHANNELS],
784
                               int block_num)
785
{
786
    int ch, nb_groups, group_size, i, baie, rbnd;
787
    uint8_t *p;
788
    uint16_t qmant[AC3_MAX_CHANNELS][N/2];
789
    int exp0, exp1;
790
    int mant1_cnt, mant2_cnt, mant4_cnt;
791
    uint16_t *qmant1_ptr, *qmant2_ptr, *qmant4_ptr;
792
    int delta0, delta1, delta2;
793

    
794
    for(ch=0;ch<s->nb_channels;ch++)
795
        put_bits(&s->pb, 1, 0); /* 512 point MDCT */
796
    for(ch=0;ch<s->nb_channels;ch++)
797
        put_bits(&s->pb, 1, 1); /* no dither */
798
    put_bits(&s->pb, 1, 0); /* no dynamic range */
799
    if (block_num == 0) {
800
        /* for block 0, even if no coupling, we must say it. This is a
801
           waste of bit :-) */
802
        put_bits(&s->pb, 1, 1); /* coupling strategy present */
803
        put_bits(&s->pb, 1, 0); /* no coupling strategy */
804
    } else {
805
        put_bits(&s->pb, 1, 0); /* no new coupling strategy */
806
    }
807

    
808
    if (s->channel_mode == AC3_CHMODE_STEREO)
809
      {
810
        if(block_num==0)
811
          {
812
            /* first block must define rematrixing (rematstr)  */
813
            put_bits(&s->pb, 1, 1);
814

    
815
            /* dummy rematrixing rematflg(1:4)=0 */
816
            for (rbnd=0;rbnd<4;rbnd++)
817
              put_bits(&s->pb, 1, 0);
818
          }
819
        else
820
          {
821
            /* no matrixing (but should be used in the future) */
822
            put_bits(&s->pb, 1, 0);
823
          }
824
      }
825

    
826
#if defined(DEBUG)
827
    {
828
      static int count = 0;
829
      av_log(NULL, AV_LOG_DEBUG, "Block #%d (%d)\n", block_num, count++);
830
    }
831
#endif
832
    /* exponent strategy */
833
    for(ch=0;ch<s->nb_channels;ch++) {
834
        put_bits(&s->pb, 2, exp_strategy[ch]);
835
    }
836

    
837
    if (s->lfe) {
838
        put_bits(&s->pb, 1, exp_strategy[s->lfe_channel]);
839
    }
840

    
841
    for(ch=0;ch<s->nb_channels;ch++) {
842
        if (exp_strategy[ch] != EXP_REUSE)
843
            put_bits(&s->pb, 6, s->chbwcod[ch]);
844
    }
845

    
846
    /* exponents */
847
    for (ch = 0; ch < s->nb_all_channels; ch++) {
848
        switch(exp_strategy[ch]) {
849
        case EXP_REUSE:
850
            continue;
851
        case EXP_D15:
852
            group_size = 1;
853
            break;
854
        case EXP_D25:
855
            group_size = 2;
856
            break;
857
        default:
858
        case EXP_D45:
859
            group_size = 4;
860
            break;
861
        }
862
        nb_groups = (s->nb_coefs[ch] + (group_size * 3) - 4) / (3 * group_size);
863
        p = encoded_exp[ch];
864

    
865
        /* first exponent */
866
        exp1 = *p++;
867
        put_bits(&s->pb, 4, exp1);
868

    
869
        /* next ones are delta encoded */
870
        for(i=0;i<nb_groups;i++) {
871
            /* merge three delta in one code */
872
            exp0 = exp1;
873
            exp1 = p[0];
874
            p += group_size;
875
            delta0 = exp1 - exp0 + 2;
876

    
877
            exp0 = exp1;
878
            exp1 = p[0];
879
            p += group_size;
880
            delta1 = exp1 - exp0 + 2;
881

    
882
            exp0 = exp1;
883
            exp1 = p[0];
884
            p += group_size;
885
            delta2 = exp1 - exp0 + 2;
886

    
887
            put_bits(&s->pb, 7, ((delta0 * 5 + delta1) * 5) + delta2);
888
        }
889

    
890
        if (ch != s->lfe_channel)
891
            put_bits(&s->pb, 2, 0); /* no gain range info */
892
    }
893

    
894
    /* bit allocation info */
895
    baie = (block_num == 0);
896
    put_bits(&s->pb, 1, baie);
897
    if (baie) {
898
        put_bits(&s->pb, 2, s->slow_decay_code);
899
        put_bits(&s->pb, 2, s->fast_decay_code);
900
        put_bits(&s->pb, 2, s->slow_gain_code);
901
        put_bits(&s->pb, 2, s->db_per_bit_code);
902
        put_bits(&s->pb, 3, s->floor_code);
903
    }
904

    
905
    /* snr offset */
906
    put_bits(&s->pb, 1, baie); /* always present with bai */
907
    if (baie) {
908
        put_bits(&s->pb, 6, s->coarse_snr_offset);
909
        for(ch=0;ch<s->nb_all_channels;ch++) {
910
            put_bits(&s->pb, 4, s->fine_snr_offset[ch]);
911
            put_bits(&s->pb, 3, s->fast_gain_code[ch]);
912
        }
913
    }
914

    
915
    put_bits(&s->pb, 1, 0); /* no delta bit allocation */
916
    put_bits(&s->pb, 1, 0); /* no data to skip */
917

    
918
    /* mantissa encoding : we use two passes to handle the grouping. A
919
       one pass method may be faster, but it would necessitate to
920
       modify the output stream. */
921

    
922
    /* first pass: quantize */
923
    mant1_cnt = mant2_cnt = mant4_cnt = 0;
924
    qmant1_ptr = qmant2_ptr = qmant4_ptr = NULL;
925

    
926
    for (ch = 0; ch < s->nb_all_channels; ch++) {
927
        int b, c, e, v;
928

    
929
        for(i=0;i<s->nb_coefs[ch];i++) {
930
            c = mdct_coefs[ch][i];
931
            e = encoded_exp[ch][i] - global_exp[ch];
932
            b = bap[ch][i];
933
            switch(b) {
934
            case 0:
935
                v = 0;
936
                break;
937
            case 1:
938
                v = sym_quant(c, e, 3);
939
                switch(mant1_cnt) {
940
                case 0:
941
                    qmant1_ptr = &qmant[ch][i];
942
                    v = 9 * v;
943
                    mant1_cnt = 1;
944
                    break;
945
                case 1:
946
                    *qmant1_ptr += 3 * v;
947
                    mant1_cnt = 2;
948
                    v = 128;
949
                    break;
950
                default:
951
                    *qmant1_ptr += v;
952
                    mant1_cnt = 0;
953
                    v = 128;
954
                    break;
955
                }
956
                break;
957
            case 2:
958
                v = sym_quant(c, e, 5);
959
                switch(mant2_cnt) {
960
                case 0:
961
                    qmant2_ptr = &qmant[ch][i];
962
                    v = 25 * v;
963
                    mant2_cnt = 1;
964
                    break;
965
                case 1:
966
                    *qmant2_ptr += 5 * v;
967
                    mant2_cnt = 2;
968
                    v = 128;
969
                    break;
970
                default:
971
                    *qmant2_ptr += v;
972
                    mant2_cnt = 0;
973
                    v = 128;
974
                    break;
975
                }
976
                break;
977
            case 3:
978
                v = sym_quant(c, e, 7);
979
                break;
980
            case 4:
981
                v = sym_quant(c, e, 11);
982
                switch(mant4_cnt) {
983
                case 0:
984
                    qmant4_ptr = &qmant[ch][i];
985
                    v = 11 * v;
986
                    mant4_cnt = 1;
987
                    break;
988
                default:
989
                    *qmant4_ptr += v;
990
                    mant4_cnt = 0;
991
                    v = 128;
992
                    break;
993
                }
994
                break;
995
            case 5:
996
                v = sym_quant(c, e, 15);
997
                break;
998
            case 14:
999
                v = asym_quant(c, e, 14);
1000
                break;
1001
            case 15:
1002
                v = asym_quant(c, e, 16);
1003
                break;
1004
            default:
1005
                v = asym_quant(c, e, b - 1);
1006
                break;
1007
            }
1008
            qmant[ch][i] = v;
1009
        }
1010
    }
1011

    
1012
    /* second pass : output the values */
1013
    for (ch = 0; ch < s->nb_all_channels; ch++) {
1014
        int b, q;
1015

    
1016
        for(i=0;i<s->nb_coefs[ch];i++) {
1017
            q = qmant[ch][i];
1018
            b = bap[ch][i];
1019
            switch(b) {
1020
            case 0:
1021
                break;
1022
            case 1:
1023
                if (q != 128)
1024
                    put_bits(&s->pb, 5, q);
1025
                break;
1026
            case 2:
1027
                if (q != 128)
1028
                    put_bits(&s->pb, 7, q);
1029
                break;
1030
            case 3:
1031
                put_bits(&s->pb, 3, q);
1032
                break;
1033
            case 4:
1034
                if (q != 128)
1035
                    put_bits(&s->pb, 7, q);
1036
                break;
1037
            case 14:
1038
                put_bits(&s->pb, 14, q);
1039
                break;
1040
            case 15:
1041
                put_bits(&s->pb, 16, q);
1042
                break;
1043
            default:
1044
                put_bits(&s->pb, b - 1, q);
1045
                break;
1046
            }
1047
        }
1048
    }
1049
}
1050

    
1051
#define CRC16_POLY ((1 << 0) | (1 << 2) | (1 << 15) | (1 << 16))
1052

    
1053
static unsigned int mul_poly(unsigned int a, unsigned int b, unsigned int poly)
1054
{
1055
    unsigned int c;
1056

    
1057
    c = 0;
1058
    while (a) {
1059
        if (a & 1)
1060
            c ^= b;
1061
        a = a >> 1;
1062
        b = b << 1;
1063
        if (b & (1 << 16))
1064
            b ^= poly;
1065
    }
1066
    return c;
1067
}
1068

    
1069
static unsigned int pow_poly(unsigned int a, unsigned int n, unsigned int poly)
1070
{
1071
    unsigned int r;
1072
    r = 1;
1073
    while (n) {
1074
        if (n & 1)
1075
            r = mul_poly(r, a, poly);
1076
        a = mul_poly(a, a, poly);
1077
        n >>= 1;
1078
    }
1079
    return r;
1080
}
1081

    
1082

    
1083
/* compute log2(max(abs(tab[]))) */
1084
static int log2_tab(int16_t *tab, int n)
1085
{
1086
    int i, v;
1087

    
1088
    v = 0;
1089
    for(i=0;i<n;i++) {
1090
        v |= abs(tab[i]);
1091
    }
1092
    return av_log2(v);
1093
}
1094

    
1095
static void lshift_tab(int16_t *tab, int n, int lshift)
1096
{
1097
    int i;
1098

    
1099
    if (lshift > 0) {
1100
        for(i=0;i<n;i++) {
1101
            tab[i] <<= lshift;
1102
        }
1103
    } else if (lshift < 0) {
1104
        lshift = -lshift;
1105
        for(i=0;i<n;i++) {
1106
            tab[i] >>= lshift;
1107
        }
1108
    }
1109
}
1110

    
1111
/* fill the end of the frame and compute the two crcs */
1112
static int output_frame_end(AC3EncodeContext *s)
1113
{
1114
    int frame_size, frame_size_58, n, crc1, crc2, crc_inv;
1115
    uint8_t *frame;
1116

    
1117
    frame_size = s->frame_size; /* frame size in words */
1118
    /* align to 8 bits */
1119
    flush_put_bits(&s->pb);
1120
    /* add zero bytes to reach the frame size */
1121
    frame = s->pb.buf;
1122
    n = 2 * s->frame_size - (pbBufPtr(&s->pb) - frame) - 2;
1123
    assert(n >= 0);
1124
    if(n>0)
1125
      memset(pbBufPtr(&s->pb), 0, n);
1126

    
1127
    /* Now we must compute both crcs : this is not so easy for crc1
1128
       because it is at the beginning of the data... */
1129
    frame_size_58 = (frame_size >> 1) + (frame_size >> 3);
1130
    crc1 = bswap_16(av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0,
1131
                           frame + 4, 2 * frame_size_58 - 4));
1132
    /* XXX: could precompute crc_inv */
1133
    crc_inv = pow_poly((CRC16_POLY >> 1), (16 * frame_size_58) - 16, CRC16_POLY);
1134
    crc1 = mul_poly(crc_inv, crc1, CRC16_POLY);
1135
    AV_WB16(frame+2,crc1);
1136

    
1137
    crc2 = bswap_16(av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0,
1138
                           frame + 2 * frame_size_58,
1139
                           (frame_size - frame_size_58) * 2 - 2));
1140
    AV_WB16(frame+2*frame_size-2,crc2);
1141

    
1142
    //    printf("n=%d frame_size=%d\n", n, frame_size);
1143
    return frame_size * 2;
1144
}
1145

    
1146
static int AC3_encode_frame(AVCodecContext *avctx,
1147
                            unsigned char *frame, int buf_size, void *data)
1148
{
1149
    AC3EncodeContext *s = avctx->priv_data;
1150
    int16_t *samples = data;
1151
    int i, j, k, v, ch;
1152
    int16_t input_samples[N];
1153
    int32_t mdct_coef[NB_BLOCKS][AC3_MAX_CHANNELS][N/2];
1154
    uint8_t exp[NB_BLOCKS][AC3_MAX_CHANNELS][N/2];
1155
    uint8_t exp_strategy[NB_BLOCKS][AC3_MAX_CHANNELS];
1156
    uint8_t encoded_exp[NB_BLOCKS][AC3_MAX_CHANNELS][N/2];
1157
    uint8_t bap[NB_BLOCKS][AC3_MAX_CHANNELS][N/2];
1158
    int8_t exp_samples[NB_BLOCKS][AC3_MAX_CHANNELS];
1159
    int frame_bits;
1160

    
1161
    frame_bits = 0;
1162
    for(ch=0;ch<s->nb_all_channels;ch++) {
1163
        /* fixed mdct to the six sub blocks & exponent computation */
1164
        for(i=0;i<NB_BLOCKS;i++) {
1165
            int16_t *sptr;
1166
            int sinc;
1167

    
1168
            /* compute input samples */
1169
            memcpy(input_samples, s->last_samples[ch], N/2 * sizeof(int16_t));
1170
            sinc = s->nb_all_channels;
1171
            sptr = samples + (sinc * (N/2) * i) + ch;
1172
            for(j=0;j<N/2;j++) {
1173
                v = *sptr;
1174
                input_samples[j + N/2] = v;
1175
                s->last_samples[ch][j] = v;
1176
                sptr += sinc;
1177
            }
1178

    
1179
            /* apply the MDCT window */
1180
            for(j=0;j<N/2;j++) {
1181
                input_samples[j] = MUL16(input_samples[j],
1182
                                         ff_ac3_window[j]) >> 15;
1183
                input_samples[N-j-1] = MUL16(input_samples[N-j-1],
1184
                                             ff_ac3_window[j]) >> 15;
1185
            }
1186

    
1187
            /* Normalize the samples to use the maximum available
1188
               precision */
1189
            v = 14 - log2_tab(input_samples, N);
1190
            if (v < 0)
1191
                v = 0;
1192
            exp_samples[i][ch] = v - 9;
1193
            lshift_tab(input_samples, N, v);
1194

    
1195
            /* do the MDCT */
1196
            mdct512(mdct_coef[i][ch], input_samples);
1197

    
1198
            /* compute "exponents". We take into account the
1199
               normalization there */
1200
            for(j=0;j<N/2;j++) {
1201
                int e;
1202
                v = abs(mdct_coef[i][ch][j]);
1203
                if (v == 0)
1204
                    e = 24;
1205
                else {
1206
                    e = 23 - av_log2(v) + exp_samples[i][ch];
1207
                    if (e >= 24) {
1208
                        e = 24;
1209
                        mdct_coef[i][ch][j] = 0;
1210
                    }
1211
                }
1212
                exp[i][ch][j] = e;
1213
            }
1214
        }
1215

    
1216
        compute_exp_strategy(exp_strategy, exp, ch, ch == s->lfe_channel);
1217

    
1218
        /* compute the exponents as the decoder will see them. The
1219
           EXP_REUSE case must be handled carefully : we select the
1220
           min of the exponents */
1221
        i = 0;
1222
        while (i < NB_BLOCKS) {
1223
            j = i + 1;
1224
            while (j < NB_BLOCKS && exp_strategy[j][ch] == EXP_REUSE) {
1225
                exponent_min(exp[i][ch], exp[j][ch], s->nb_coefs[ch]);
1226
                j++;
1227
            }
1228
            frame_bits += encode_exp(encoded_exp[i][ch],
1229
                                     exp[i][ch], s->nb_coefs[ch],
1230
                                     exp_strategy[i][ch]);
1231
            /* copy encoded exponents for reuse case */
1232
            for(k=i+1;k<j;k++) {
1233
                memcpy(encoded_exp[k][ch], encoded_exp[i][ch],
1234
                       s->nb_coefs[ch] * sizeof(uint8_t));
1235
            }
1236
            i = j;
1237
        }
1238
    }
1239

    
1240
    /* adjust for fractional frame sizes */
1241
    while(s->bits_written >= s->bit_rate && s->samples_written >= s->sample_rate) {
1242
        s->bits_written -= s->bit_rate;
1243
        s->samples_written -= s->sample_rate;
1244
    }
1245
    s->frame_size = s->frame_size_min + (s->bits_written * s->sample_rate < s->samples_written * s->bit_rate);
1246
    s->bits_written += s->frame_size * 16;
1247
    s->samples_written += AC3_FRAME_SIZE;
1248

    
1249
    compute_bit_allocation(s, bap, encoded_exp, exp_strategy, frame_bits);
1250
    /* everything is known... let's output the frame */
1251
    output_frame_header(s, frame);
1252

    
1253
    for(i=0;i<NB_BLOCKS;i++) {
1254
        output_audio_block(s, exp_strategy[i], encoded_exp[i],
1255
                           bap[i], mdct_coef[i], exp_samples[i], i);
1256
    }
1257
    return output_frame_end(s);
1258
}
1259

    
1260
static int AC3_encode_close(AVCodecContext *avctx)
1261
{
1262
    av_freep(&avctx->coded_frame);
1263
    return 0;
1264
}
1265

    
1266
#if 0
1267
/*************************************************************************/
1268
/* TEST */
1269

1270
#undef random
1271
#define FN (N/4)
1272

1273
void fft_test(void)
1274
{
1275
    IComplex in[FN], in1[FN];
1276
    int k, n, i;
1277
    float sum_re, sum_im, a;
1278

1279
    /* FFT test */
1280

1281
    for(i=0;i<FN;i++) {
1282
        in[i].re = random() % 65535 - 32767;
1283
        in[i].im = random() % 65535 - 32767;
1284
        in1[i] = in[i];
1285
    }
1286
    fft(in, 7);
1287

1288
    /* do it by hand */
1289
    for(k=0;k<FN;k++) {
1290
        sum_re = 0;
1291
        sum_im = 0;
1292
        for(n=0;n<FN;n++) {
1293
            a = -2 * M_PI * (n * k) / FN;
1294
            sum_re += in1[n].re * cos(a) - in1[n].im * sin(a);
1295
            sum_im += in1[n].re * sin(a) + in1[n].im * cos(a);
1296
        }
1297
        printf("%3d: %6d,%6d %6.0f,%6.0f\n",
1298
               k, in[k].re, in[k].im, sum_re / FN, sum_im / FN);
1299
    }
1300
}
1301

1302
void mdct_test(void)
1303
{
1304
    int16_t input[N];
1305
    int32_t output[N/2];
1306
    float input1[N];
1307
    float output1[N/2];
1308
    float s, a, err, e, emax;
1309
    int i, k, n;
1310

1311
    for(i=0;i<N;i++) {
1312
        input[i] = (random() % 65535 - 32767) * 9 / 10;
1313
        input1[i] = input[i];
1314
    }
1315

1316
    mdct512(output, input);
1317

1318
    /* do it by hand */
1319
    for(k=0;k<N/2;k++) {
1320
        s = 0;
1321
        for(n=0;n<N;n++) {
1322
            a = (2*M_PI*(2*n+1+N/2)*(2*k+1) / (4 * N));
1323
            s += input1[n] * cos(a);
1324
        }
1325
        output1[k] = -2 * s / N;
1326
    }
1327

1328
    err = 0;
1329
    emax = 0;
1330
    for(i=0;i<N/2;i++) {
1331
        printf("%3d: %7d %7.0f\n", i, output[i], output1[i]);
1332
        e = output[i] - output1[i];
1333
        if (e > emax)
1334
            emax = e;
1335
        err += e * e;
1336
    }
1337
    printf("err2=%f emax=%f\n", err / (N/2), emax);
1338
}
1339

1340
void test_ac3(void)
1341
{
1342
    AC3EncodeContext ctx;
1343
    unsigned char frame[AC3_MAX_CODED_FRAME_SIZE];
1344
    short samples[AC3_FRAME_SIZE];
1345
    int ret, i;
1346

1347
    AC3_encode_init(&ctx, 44100, 64000, 1);
1348

1349
    fft_test();
1350
    mdct_test();
1351

1352
    for(i=0;i<AC3_FRAME_SIZE;i++)
1353
        samples[i] = (int)(sin(2*M_PI*i*1000.0/44100) * 10000);
1354
    ret = AC3_encode_frame(&ctx, frame, samples);
1355
    printf("ret=%d\n", ret);
1356
}
1357
#endif
1358

    
1359
AVCodec ac3_encoder = {
1360
    "ac3",
1361
    CODEC_TYPE_AUDIO,
1362
    CODEC_ID_AC3,
1363
    sizeof(AC3EncodeContext),
1364
    AC3_encode_init,
1365
    AC3_encode_frame,
1366
    AC3_encode_close,
1367
    NULL,
1368
};