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1 de6d9b64 Fabrice Bellard
/*
2
 * The simplest AC3 encoder
3 ff4ec49e Fabrice Bellard
 * Copyright (c) 2000 Fabrice Bellard.
4 de6d9b64 Fabrice Bellard
 *
5 ff4ec49e Fabrice Bellard
 * This library is free software; you can redistribute it and/or
6
 * modify it under the terms of the GNU Lesser General Public
7
 * License as published by the Free Software Foundation; either
8
 * version 2 of the License, or (at your option) any later version.
9 de6d9b64 Fabrice Bellard
 *
10 ff4ec49e Fabrice Bellard
 * This library is distributed in the hope that it will be useful,
11 de6d9b64 Fabrice Bellard
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 ff4ec49e Fabrice Bellard
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
13
 * Lesser General Public License for more details.
14 de6d9b64 Fabrice Bellard
 *
15 ff4ec49e Fabrice Bellard
 * You should have received a copy of the GNU Lesser General Public
16
 * License along with this library; if not, write to the Free Software
17
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
18 de6d9b64 Fabrice Bellard
 */
19 983e3246 Michael Niedermayer
20
/**
21
 * @file ac3enc.c
22
 * The simplest AC3 encoder.
23
 */
24 1a565432 Fabrice Bellard
//#define DEBUG
25
//#define DEBUG_BITALLOC
26 de6d9b64 Fabrice Bellard
#include "avcodec.h"
27
28 6107fa87 Fabrice Bellard
#include "ac3.h"
29
30
typedef struct AC3EncodeContext {
31
    PutBitContext pb;
32
    int nb_channels;
33
    int nb_all_channels;
34
    int lfe_channel;
35
    int bit_rate;
36 5c91a675 Zdenek Kabelac
    unsigned int sample_rate;
37
    unsigned int bsid;
38
    unsigned int frame_size_min; /* minimum frame size in case rounding is necessary */
39
    unsigned int frame_size; /* current frame size in words */
40 6107fa87 Fabrice Bellard
    int halfratecod;
41 5c91a675 Zdenek Kabelac
    unsigned int frmsizecod;
42
    unsigned int fscod; /* frequency */
43
    unsigned int acmod;
44 6107fa87 Fabrice Bellard
    int lfe;
45 5c91a675 Zdenek Kabelac
    unsigned int bsmod;
46 6107fa87 Fabrice Bellard
    short last_samples[AC3_MAX_CHANNELS][256];
47 5c91a675 Zdenek Kabelac
    unsigned int chbwcod[AC3_MAX_CHANNELS];
48 6107fa87 Fabrice Bellard
    int nb_coefs[AC3_MAX_CHANNELS];
49
    
50
    /* bitrate allocation control */
51
    int sgaincod, sdecaycod, fdecaycod, dbkneecod, floorcod; 
52
    AC3BitAllocParameters bit_alloc;
53
    int csnroffst;
54
    int fgaincod[AC3_MAX_CHANNELS];
55
    int fsnroffst[AC3_MAX_CHANNELS];
56
    /* mantissa encoding */
57
    int mant1_cnt, mant2_cnt, mant4_cnt;
58
} AC3EncodeContext;
59 de6d9b64 Fabrice Bellard
60 6107fa87 Fabrice Bellard
#include "ac3tab.h"
61 de6d9b64 Fabrice Bellard
62
#define MDCT_NBITS 9
63
#define N         (1 << MDCT_NBITS)
64
65
/* new exponents are sent if their Norm 1 exceed this number */
66
#define EXP_DIFF_THRESHOLD 1000
67
68
static void fft_init(int ln);
69
static void ac3_crc_init(void);
70
71 0c1a9eda Zdenek Kabelac
static inline int16_t fix15(float a)
72 de6d9b64 Fabrice Bellard
{
73
    int v;
74
    v = (int)(a * (float)(1 << 15));
75
    if (v < -32767)
76
        v = -32767;
77
    else if (v > 32767) 
78
        v = 32767;
79
    return v;
80
}
81
82
static inline int calc_lowcomp1(int a, int b0, int b1)
83
{
84
    if ((b0 + 256) == b1) {
85
        a = 384 ;
86
    } else if (b0 > b1) { 
87
        a = a - 64;
88
        if (a < 0) a=0;
89
    }
90
    return a;
91
}
92
93
static inline int calc_lowcomp(int a, int b0, int b1, int bin)
94
{
95
    if (bin < 7) {
96
        if ((b0 + 256) == b1) {
97
            a = 384 ;
98
        } else if (b0 > b1) { 
99
            a = a - 64;
100
            if (a < 0) a=0;
101
        }
102
    } else if (bin < 20) {
103
        if ((b0 + 256) == b1) {
104
            a = 320 ;
105
        } else if (b0 > b1) {
106
            a= a - 64;
107
            if (a < 0) a=0;
108
        }
109
    } else {
110
        a = a - 128;
111
        if (a < 0) a=0;
112
    }
113
    return a;
114
}
115
116
/* AC3 bit allocation. The algorithm is the one described in the AC3
117 6107fa87 Fabrice Bellard
   spec. */
118 0c1a9eda Zdenek Kabelac
void ac3_parametric_bit_allocation(AC3BitAllocParameters *s, uint8_t *bap,
119
                                   int8_t *exp, int start, int end,
120 6107fa87 Fabrice Bellard
                                   int snroffset, int fgain, int is_lfe,
121
                                   int deltbae,int deltnseg, 
122 0c1a9eda Zdenek Kabelac
                                   uint8_t *deltoffst, uint8_t *deltlen, uint8_t *deltba)
123 de6d9b64 Fabrice Bellard
{
124
    int bin,i,j,k,end1,v,v1,bndstrt,bndend,lowcomp,begin;
125
    int fastleak,slowleak,address,tmp;
126 0c1a9eda Zdenek Kabelac
    int16_t psd[256]; /* scaled exponents */
127
    int16_t bndpsd[50]; /* interpolated exponents */
128
    int16_t excite[50]; /* excitation */
129
    int16_t mask[50];   /* masking value */
130 de6d9b64 Fabrice Bellard
131
    /* exponent mapping to PSD */
132
    for(bin=start;bin<end;bin++) {
133
        psd[bin]=(3072 - (exp[bin] << 7));
134
    }
135
136
    /* PSD integration */
137
    j=start;
138
    k=masktab[start];
139
    do {
140
        v=psd[j];
141
        j++;
142
        end1=bndtab[k+1];
143
        if (end1 > end) end1=end;
144
        for(i=j;i<end1;i++) {
145
            int c,adr;
146
            /* logadd */
147
            v1=psd[j];
148
            c=v-v1;
149
            if (c >= 0) {
150
                adr=c >> 1;
151
                if (adr > 255) adr=255;
152
                v=v + latab[adr];
153
            } else {
154
                adr=(-c) >> 1;
155
                if (adr > 255) adr=255;
156
                v=v1 + latab[adr];
157
            }
158
            j++;
159
        }
160
        bndpsd[k]=v;
161
        k++;
162
    } while (end > bndtab[k]);
163
164
    /* excitation function */
165
    bndstrt = masktab[start];
166
    bndend = masktab[end-1] + 1;
167
    
168 6107fa87 Fabrice Bellard
    if (bndstrt == 0) {
169
        lowcomp = 0;
170
        lowcomp = calc_lowcomp1(lowcomp, bndpsd[0], bndpsd[1]) ;
171
        excite[0] = bndpsd[0] - fgain - lowcomp ;
172
        lowcomp = calc_lowcomp1(lowcomp, bndpsd[1], bndpsd[2]) ;
173
        excite[1] = bndpsd[1] - fgain - lowcomp ;
174
        begin = 7 ;
175
        for (bin = 2; bin < 7; bin++) {
176
            if (!(is_lfe && bin == 6))
177
                lowcomp = calc_lowcomp1(lowcomp, bndpsd[bin], bndpsd[bin+1]) ;
178
            fastleak = bndpsd[bin] - fgain ;
179
            slowleak = bndpsd[bin] - s->sgain ;
180
            excite[bin] = fastleak - lowcomp ;
181
            if (!(is_lfe && bin == 6)) {
182
                if (bndpsd[bin] <= bndpsd[bin+1]) {
183
                    begin = bin + 1 ;
184
                    break ;
185
                }
186
            }
187
        }
188 de6d9b64 Fabrice Bellard
    
189 6107fa87 Fabrice Bellard
        end1=bndend;
190
        if (end1 > 22) end1=22;
191 de6d9b64 Fabrice Bellard
    
192 6107fa87 Fabrice Bellard
        for (bin = begin; bin < end1; bin++) {
193
            if (!(is_lfe && bin == 6))
194
                lowcomp = calc_lowcomp(lowcomp, bndpsd[bin], bndpsd[bin+1], bin) ;
195 de6d9b64 Fabrice Bellard
        
196 6107fa87 Fabrice Bellard
            fastleak -= s->fdecay ;
197
            v = bndpsd[bin] - fgain;
198
            if (fastleak < v) fastleak = v;
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200 6107fa87 Fabrice Bellard
            slowleak -= s->sdecay ;
201
            v = bndpsd[bin] - s->sgain;
202
            if (slowleak < v) slowleak = v;
203 de6d9b64 Fabrice Bellard
        
204 6107fa87 Fabrice Bellard
            v=fastleak - lowcomp;
205
            if (slowleak > v) v=slowleak;
206 de6d9b64 Fabrice Bellard
        
207 6107fa87 Fabrice Bellard
            excite[bin] = v;
208
        }
209
        begin = 22;
210
    } else {
211
        /* coupling channel */
212
        begin = bndstrt;
213
        
214
        fastleak = (s->cplfleak << 8) + 768;
215
        slowleak = (s->cplsleak << 8) + 768;
216 de6d9b64 Fabrice Bellard
    }
217
218 6107fa87 Fabrice Bellard
    for (bin = begin; bin < bndend; bin++) {
219 de6d9b64 Fabrice Bellard
        fastleak -= s->fdecay ;
220
        v = bndpsd[bin] - fgain;
221
        if (fastleak < v) fastleak = v;
222
        slowleak -= s->sdecay ;
223
        v = bndpsd[bin] - s->sgain;
224
        if (slowleak < v) slowleak = v;
225
226
        v=fastleak;
227
        if (slowleak > v) v = slowleak;
228
        excite[bin] = v;
229
    }
230
231
    /* compute masking curve */
232
233
    for (bin = bndstrt; bin < bndend; bin++) {
234
        v1 = excite[bin];
235
        tmp = s->dbknee - bndpsd[bin];
236
        if (tmp > 0) {
237
            v1 += tmp >> 2;
238
        }
239
        v=hth[bin >> s->halfratecod][s->fscod];
240
        if (v1 > v) v=v1;
241
        mask[bin] = v;
242
    }
243
244 6107fa87 Fabrice Bellard
    /* delta bit allocation */
245
246
    if (deltbae == 0 || deltbae == 1) {
247
        int band, seg, delta;
248
        band = 0 ;
249
        for (seg = 0; seg < deltnseg; seg++) {
250
            band += deltoffst[seg] ;
251
            if (deltba[seg] >= 4) {
252
                delta = (deltba[seg] - 3) << 7;
253
            } else {
254
                delta = (deltba[seg] - 4) << 7;
255
            }
256
            for (k = 0; k < deltlen[seg]; k++) {
257
                mask[band] += delta ;
258
                band++ ;
259
            }
260
        }
261
    }
262
263 de6d9b64 Fabrice Bellard
    /* compute bit allocation */
264
    
265
    i = start ;
266
    j = masktab[start] ;
267
    do {
268
        v=mask[j];
269
        v -= snroffset ;
270
        v -= s->floor ;
271
        if (v < 0) v = 0;
272
        v &= 0x1fe0 ;
273
        v += s->floor ;
274
275
        end1=bndtab[j] + bndsz[j];
276
        if (end1 > end) end1=end;
277
278
        for (k = i; k < end1; k++) {
279
            address = (psd[i] - v) >> 5 ;
280
            if (address < 0) address=0;
281
            else if (address > 63) address=63;
282
            bap[i] = baptab[address];
283
            i++;
284
        }
285
    } while (end > bndtab[j++]) ;
286
}
287
288
typedef struct IComplex {
289
    short re,im;
290
} IComplex;
291
292
static void fft_init(int ln)
293
{
294
    int i, j, m, n;
295
    float alpha;
296
297
    n = 1 << ln;
298
299
    for(i=0;i<(n/2);i++) {
300
        alpha = 2 * M_PI * (float)i / (float)n;
301
        costab[i] = fix15(cos(alpha));
302
        sintab[i] = fix15(sin(alpha));
303
    }
304
305
    for(i=0;i<n;i++) {
306
        m=0;
307
        for(j=0;j<ln;j++) {
308
            m |= ((i >> j) & 1) << (ln-j-1);
309
        }
310
        fft_rev[i]=m;
311
    }
312
}
313
314
/* butter fly op */
315
#define BF(pre, pim, qre, qim, pre1, pim1, qre1, qim1) \
316
{\
317
  int ax, ay, bx, by;\
318
  bx=pre1;\
319
  by=pim1;\
320
  ax=qre1;\
321
  ay=qim1;\
322
  pre = (bx + ax) >> 1;\
323
  pim = (by + ay) >> 1;\
324
  qre = (bx - ax) >> 1;\
325
  qim = (by - ay) >> 1;\
326
}
327
328
#define MUL16(a,b) ((a) * (b))
329
330
#define CMUL(pre, pim, are, aim, bre, bim) \
331
{\
332
   pre = (MUL16(are, bre) - MUL16(aim, bim)) >> 15;\
333
   pim = (MUL16(are, bim) + MUL16(bre, aim)) >> 15;\
334
}
335
336
337
/* do a 2^n point complex fft on 2^ln points. */
338
static void fft(IComplex *z, int ln)
339
{
340
    int        j, l, np, np2;
341
    int        nblocks, nloops;
342
    register IComplex *p,*q;
343
    int tmp_re, tmp_im;
344
345
    np = 1 << ln;
346
347
    /* reverse */
348
    for(j=0;j<np;j++) {
349
        int k;
350
        IComplex tmp;
351
        k = fft_rev[j];
352
        if (k < j) {
353
            tmp = z[k];
354
            z[k] = z[j];
355
            z[j] = tmp;
356
        }
357
    }
358
359
    /* pass 0 */
360
361
    p=&z[0];
362
    j=(np >> 1);
363
    do {
364
        BF(p[0].re, p[0].im, p[1].re, p[1].im, 
365
           p[0].re, p[0].im, p[1].re, p[1].im);
366
        p+=2;
367
    } while (--j != 0);
368
369
    /* pass 1 */
370
371
    p=&z[0];
372
    j=np >> 2;
373
    do {
374
        BF(p[0].re, p[0].im, p[2].re, p[2].im, 
375
           p[0].re, p[0].im, p[2].re, p[2].im);
376
        BF(p[1].re, p[1].im, p[3].re, p[3].im, 
377
           p[1].re, p[1].im, p[3].im, -p[3].re);
378
        p+=4;
379
    } while (--j != 0);
380
381
    /* pass 2 .. ln-1 */
382
383
    nblocks = np >> 3;
384
    nloops = 1 << 2;
385
    np2 = np >> 1;
386
    do {
387
        p = z;
388
        q = z + nloops;
389
        for (j = 0; j < nblocks; ++j) {
390
391
            BF(p->re, p->im, q->re, q->im,
392
               p->re, p->im, q->re, q->im);
393
            
394
            p++;
395
            q++;
396
            for(l = nblocks; l < np2; l += nblocks) {
397
                CMUL(tmp_re, tmp_im, costab[l], -sintab[l], q->re, q->im);
398
                BF(p->re, p->im, q->re, q->im,
399
                   p->re, p->im, tmp_re, tmp_im);
400
                p++;
401
                q++;
402
            }
403
            p += nloops;
404
            q += nloops;
405
        }
406
        nblocks = nblocks >> 1;
407
        nloops = nloops << 1;
408
    } while (nblocks != 0);
409
}
410
411
/* do a 512 point mdct */
412 0c1a9eda Zdenek Kabelac
static void mdct512(int32_t *out, int16_t *in)
413 de6d9b64 Fabrice Bellard
{
414
    int i, re, im, re1, im1;
415 0c1a9eda Zdenek Kabelac
    int16_t rot[N]; 
416 de6d9b64 Fabrice Bellard
    IComplex x[N/4];
417
418
    /* shift to simplify computations */
419
    for(i=0;i<N/4;i++)
420
        rot[i] = -in[i + 3*N/4];
421
    for(i=N/4;i<N;i++)
422
        rot[i] = in[i - N/4];
423
        
424
    /* pre rotation */
425
    for(i=0;i<N/4;i++) {
426
        re = ((int)rot[2*i] - (int)rot[N-1-2*i]) >> 1;
427
        im = -((int)rot[N/2+2*i] - (int)rot[N/2-1-2*i]) >> 1;
428
        CMUL(x[i].re, x[i].im, re, im, -xcos1[i], xsin1[i]);
429
    }
430
431
    fft(x, MDCT_NBITS - 2);
432
  
433
    /* post rotation */
434
    for(i=0;i<N/4;i++) {
435
        re = x[i].re;
436
        im = x[i].im;
437
        CMUL(re1, im1, re, im, xsin1[i], xcos1[i]);
438
        out[2*i] = im1;
439
        out[N/2-1-2*i] = re1;
440
    }
441
}
442
443
/* XXX: use another norm ? */
444 0c1a9eda Zdenek Kabelac
static int calc_exp_diff(uint8_t *exp1, uint8_t *exp2, int n)
445 de6d9b64 Fabrice Bellard
{
446
    int sum, i;
447
    sum = 0;
448
    for(i=0;i<n;i++) {
449
        sum += abs(exp1[i] - exp2[i]);
450
    }
451
    return sum;
452
}
453
454 0c1a9eda Zdenek Kabelac
static void compute_exp_strategy(uint8_t exp_strategy[NB_BLOCKS][AC3_MAX_CHANNELS],
455
                                 uint8_t exp[NB_BLOCKS][AC3_MAX_CHANNELS][N/2],
456 30b68f33 Zdenek Kabelac
                                 int ch, int is_lfe)
457 de6d9b64 Fabrice Bellard
{
458
    int i, j;
459
    int exp_diff;
460
    
461
    /* estimate if the exponent variation & decide if they should be
462
       reused in the next frame */
463
    exp_strategy[0][ch] = EXP_NEW;
464
    for(i=1;i<NB_BLOCKS;i++) {
465
        exp_diff = calc_exp_diff(exp[i][ch], exp[i-1][ch], N/2);
466
#ifdef DEBUG            
467 3d0ef6dd Michael Niedermayer
        av_log(NULL, AV_LOG_DEBUG, "exp_diff=%d\n", exp_diff);
468 de6d9b64 Fabrice Bellard
#endif
469
        if (exp_diff > EXP_DIFF_THRESHOLD)
470
            exp_strategy[i][ch] = EXP_NEW;
471
        else
472
            exp_strategy[i][ch] = EXP_REUSE;
473
    }
474 30b68f33 Zdenek Kabelac
    if (is_lfe)
475
        return;
476
477 de6d9b64 Fabrice Bellard
    /* now select the encoding strategy type : if exponents are often
478
       recoded, we use a coarse encoding */
479
    i = 0;
480
    while (i < NB_BLOCKS) {
481
        j = i + 1;
482
        while (j < NB_BLOCKS && exp_strategy[j][ch] == EXP_REUSE)
483
            j++;
484
        switch(j - i) {
485
        case 1:
486
            exp_strategy[i][ch] = EXP_D45;
487
            break;
488
        case 2:
489
        case 3:
490
            exp_strategy[i][ch] = EXP_D25;
491
            break;
492
        default:
493
            exp_strategy[i][ch] = EXP_D15;
494
            break;
495
        }
496 30b68f33 Zdenek Kabelac
        i = j;
497 de6d9b64 Fabrice Bellard
    }
498
}
499
500
/* set exp[i] to min(exp[i], exp1[i]) */
501 0c1a9eda Zdenek Kabelac
static void exponent_min(uint8_t exp[N/2], uint8_t exp1[N/2], int n)
502 de6d9b64 Fabrice Bellard
{
503
    int i;
504
505
    for(i=0;i<n;i++) {
506
        if (exp1[i] < exp[i])
507
            exp[i] = exp1[i];
508
    }
509
}
510
                                 
511
/* update the exponents so that they are the ones the decoder will
512
   decode. Return the number of bits used to code the exponents */
513 0c1a9eda Zdenek Kabelac
static int encode_exp(uint8_t encoded_exp[N/2], 
514
                      uint8_t exp[N/2], 
515 de6d9b64 Fabrice Bellard
                      int nb_exps,
516
                      int exp_strategy)
517
{
518
    int group_size, nb_groups, i, j, k, recurse, exp_min, delta;
519 0c1a9eda Zdenek Kabelac
    uint8_t exp1[N/2];
520 de6d9b64 Fabrice Bellard
521
    switch(exp_strategy) {
522
    case EXP_D15:
523
        group_size = 1;
524
        break;
525
    case EXP_D25:
526
        group_size = 2;
527
        break;
528
    default:
529
    case EXP_D45:
530
        group_size = 4;
531
        break;
532
    }
533
    nb_groups = ((nb_exps + (group_size * 3) - 4) / (3 * group_size)) * 3;
534
535
    /* for each group, compute the minimum exponent */
536
    exp1[0] = exp[0]; /* DC exponent is handled separately */
537
    k = 1;
538
    for(i=1;i<=nb_groups;i++) {
539
        exp_min = exp[k];
540
        assert(exp_min >= 0 && exp_min <= 24);
541
        for(j=1;j<group_size;j++) {
542
            if (exp[k+j] < exp_min)
543
                exp_min = exp[k+j];
544
        }
545
        exp1[i] = exp_min;
546
        k += group_size;
547
    }
548
549
    /* constraint for DC exponent */
550
    if (exp1[0] > 15)
551
        exp1[0] = 15;
552
553
    /* Iterate until the delta constraints between each groups are
554
       satisfyed. I'm sure it is possible to find a better algorithm,
555
       but I am lazy */
556
    do {
557
        recurse = 0;
558
        for(i=1;i<=nb_groups;i++) {
559
            delta = exp1[i] - exp1[i-1];
560
            if (delta > 2) {
561
                /* if delta too big, we encode a smaller exponent */
562
                exp1[i] = exp1[i-1] + 2;
563
            } else if (delta < -2) {
564
                /* if delta is too small, we must decrease the previous
565
               exponent, which means we must recurse */
566
                recurse = 1;
567
                exp1[i-1] = exp1[i] + 2;
568
            }
569
        }
570
    } while (recurse);
571
    
572
    /* now we have the exponent values the decoder will see */
573
    encoded_exp[0] = exp1[0];
574
    k = 1;
575
    for(i=1;i<=nb_groups;i++) {
576
        for(j=0;j<group_size;j++) {
577
            encoded_exp[k+j] = exp1[i];
578
        }
579
        k += group_size;
580
    }
581
    
582
#if defined(DEBUG)
583 3d0ef6dd Michael Niedermayer
    av_log(NULL, AV_LOG_DEBUG, "exponents: strategy=%d\n", exp_strategy);
584 de6d9b64 Fabrice Bellard
    for(i=0;i<=nb_groups * group_size;i++) {
585 3d0ef6dd Michael Niedermayer
        av_log(NULL, AV_LOG_DEBUG, "%d ", encoded_exp[i]);
586 de6d9b64 Fabrice Bellard
    }
587 3d0ef6dd Michael Niedermayer
    av_log(NULL, AV_LOG_DEBUG, "\n");
588 de6d9b64 Fabrice Bellard
#endif
589
590
    return 4 + (nb_groups / 3) * 7;
591
}
592
593
/* return the size in bits taken by the mantissa */
594 0c1a9eda Zdenek Kabelac
static int compute_mantissa_size(AC3EncodeContext *s, uint8_t *m, int nb_coefs)
595 de6d9b64 Fabrice Bellard
{
596
    int bits, mant, i;
597
598
    bits = 0;
599
    for(i=0;i<nb_coefs;i++) {
600
        mant = m[i];
601
        switch(mant) {
602
        case 0:
603
            /* nothing */
604
            break;
605
        case 1:
606
            /* 3 mantissa in 5 bits */
607
            if (s->mant1_cnt == 0) 
608
                bits += 5;
609
            if (++s->mant1_cnt == 3)
610
                s->mant1_cnt = 0;
611
            break;
612
        case 2:
613
            /* 3 mantissa in 7 bits */
614
            if (s->mant2_cnt == 0) 
615
                bits += 7;
616
            if (++s->mant2_cnt == 3)
617
                s->mant2_cnt = 0;
618
            break;
619
        case 3:
620
            bits += 3;
621
            break;
622
        case 4:
623
            /* 2 mantissa in 7 bits */
624
            if (s->mant4_cnt == 0)
625
                bits += 7;
626
            if (++s->mant4_cnt == 2) 
627
                s->mant4_cnt = 0;
628
            break;
629
        case 14:
630
            bits += 14;
631
            break;
632
        case 15:
633
            bits += 16;
634
            break;
635
        default:
636
            bits += mant - 1;
637
            break;
638
        }
639
    }
640
    return bits;
641
}
642
643
644
static int bit_alloc(AC3EncodeContext *s,
645 0c1a9eda Zdenek Kabelac
                     uint8_t bap[NB_BLOCKS][AC3_MAX_CHANNELS][N/2],
646
                     uint8_t encoded_exp[NB_BLOCKS][AC3_MAX_CHANNELS][N/2],
647
                     uint8_t exp_strategy[NB_BLOCKS][AC3_MAX_CHANNELS],
648 de6d9b64 Fabrice Bellard
                     int frame_bits, int csnroffst, int fsnroffst)
649
{
650
    int i, ch;
651
652
    /* compute size */
653
    for(i=0;i<NB_BLOCKS;i++) {
654
        s->mant1_cnt = 0;
655
        s->mant2_cnt = 0;
656
        s->mant4_cnt = 0;
657 30b68f33 Zdenek Kabelac
        for(ch=0;ch<s->nb_all_channels;ch++) {
658 6107fa87 Fabrice Bellard
            ac3_parametric_bit_allocation(&s->bit_alloc, 
659 0c1a9eda Zdenek Kabelac
                                          bap[i][ch], (int8_t *)encoded_exp[i][ch], 
660 6107fa87 Fabrice Bellard
                                          0, s->nb_coefs[ch], 
661
                                          (((csnroffst-15) << 4) + 
662
                                           fsnroffst) << 2, 
663
                                          fgaintab[s->fgaincod[ch]],
664
                                          ch == s->lfe_channel,
665
                                          2, 0, NULL, NULL, NULL);
666 de6d9b64 Fabrice Bellard
            frame_bits += compute_mantissa_size(s, bap[i][ch], 
667
                                                 s->nb_coefs[ch]);
668
        }
669
    }
670
#if 0
671
    printf("csnr=%d fsnr=%d frame_bits=%d diff=%d\n", 
672
           csnroffst, fsnroffst, frame_bits, 
673
           16 * s->frame_size - ((frame_bits + 7) & ~7));
674
#endif
675
    return 16 * s->frame_size - frame_bits;
676
}
677
678
#define SNR_INC1 4
679
680
static int compute_bit_allocation(AC3EncodeContext *s,
681 0c1a9eda Zdenek Kabelac
                                  uint8_t bap[NB_BLOCKS][AC3_MAX_CHANNELS][N/2],
682
                                  uint8_t encoded_exp[NB_BLOCKS][AC3_MAX_CHANNELS][N/2],
683
                                  uint8_t exp_strategy[NB_BLOCKS][AC3_MAX_CHANNELS],
684 de6d9b64 Fabrice Bellard
                                  int frame_bits)
685
{
686
    int i, ch;
687
    int csnroffst, fsnroffst;
688 0c1a9eda Zdenek Kabelac
    uint8_t bap1[NB_BLOCKS][AC3_MAX_CHANNELS][N/2];
689 30b68f33 Zdenek Kabelac
    static int frame_bits_inc[8] = { 0, 0, 2, 2, 2, 4, 2, 4 };
690 de6d9b64 Fabrice Bellard
691
    /* init default parameters */
692
    s->sdecaycod = 2;
693
    s->fdecaycod = 1;
694
    s->sgaincod = 1;
695
    s->dbkneecod = 2;
696
    s->floorcod = 4;
697 30b68f33 Zdenek Kabelac
    for(ch=0;ch<s->nb_all_channels;ch++) 
698 de6d9b64 Fabrice Bellard
        s->fgaincod[ch] = 4;
699
    
700
    /* compute real values */
701 6107fa87 Fabrice Bellard
    s->bit_alloc.fscod = s->fscod;
702
    s->bit_alloc.halfratecod = s->halfratecod;
703
    s->bit_alloc.sdecay = sdecaytab[s->sdecaycod] >> s->halfratecod;
704
    s->bit_alloc.fdecay = fdecaytab[s->fdecaycod] >> s->halfratecod;
705
    s->bit_alloc.sgain = sgaintab[s->sgaincod];
706
    s->bit_alloc.dbknee = dbkneetab[s->dbkneecod];
707
    s->bit_alloc.floor = floortab[s->floorcod];
708
    
709 de6d9b64 Fabrice Bellard
    /* header size */
710
    frame_bits += 65;
711 30b68f33 Zdenek Kabelac
    // if (s->acmod == 2)
712
    //    frame_bits += 2;
713
    frame_bits += frame_bits_inc[s->acmod];
714 de6d9b64 Fabrice Bellard
715
    /* audio blocks */
716
    for(i=0;i<NB_BLOCKS;i++) {
717 30b68f33 Zdenek Kabelac
        frame_bits += s->nb_channels * 2 + 2; /* blksw * c, dithflag * c, dynrnge, cplstre */
718 de6d9b64 Fabrice Bellard
        if (s->acmod == 2)
719 30b68f33 Zdenek Kabelac
            frame_bits++; /* rematstr */
720
        frame_bits += 2 * s->nb_channels; /* chexpstr[2] * c */
721
        if (s->lfe)
722
            frame_bits++; /* lfeexpstr */
723 de6d9b64 Fabrice Bellard
        for(ch=0;ch<s->nb_channels;ch++) {
724
            if (exp_strategy[i][ch] != EXP_REUSE)
725 30b68f33 Zdenek Kabelac
                frame_bits += 6 + 2; /* chbwcod[6], gainrng[2] */
726 de6d9b64 Fabrice Bellard
        }
727
        frame_bits++; /* baie */
728
        frame_bits++; /* snr */
729
        frame_bits += 2; /* delta / skip */
730
    }
731
    frame_bits++; /* cplinu for block 0 */
732
    /* bit alloc info */
733 30b68f33 Zdenek Kabelac
    /* sdcycod[2], fdcycod[2], sgaincod[2], dbpbcod[2], floorcod[3] */
734
    /* csnroffset[6] */
735
    /* (fsnoffset[4] + fgaincod[4]) * c */
736
    frame_bits += 2*4 + 3 + 6 + s->nb_all_channels * (4 + 3);
737 de6d9b64 Fabrice Bellard
738 9ab2717a Michael Niedermayer
    /* auxdatae, crcrsv */
739
    frame_bits += 2;
740
741 de6d9b64 Fabrice Bellard
    /* CRC */
742
    frame_bits += 16;
743
744
    /* now the big work begins : do the bit allocation. Modify the snr
745
       offset until we can pack everything in the requested frame size */
746
747
    csnroffst = s->csnroffst;
748
    while (csnroffst >= 0 && 
749 30b68f33 Zdenek Kabelac
           bit_alloc(s, bap, encoded_exp, exp_strategy, frame_bits, csnroffst, 0) < 0)
750
        csnroffst -= SNR_INC1;
751 de6d9b64 Fabrice Bellard
    if (csnroffst < 0) {
752 9b879566 Michel Bardiaux
        av_log(NULL, AV_LOG_ERROR, "Yack, Error !!!\n");
753 30b68f33 Zdenek Kabelac
        return -1;
754 de6d9b64 Fabrice Bellard
    }
755
    while ((csnroffst + SNR_INC1) <= 63 && 
756
           bit_alloc(s, bap1, encoded_exp, exp_strategy, frame_bits, 
757
                     csnroffst + SNR_INC1, 0) >= 0) {
758
        csnroffst += SNR_INC1;
759
        memcpy(bap, bap1, sizeof(bap1));
760
    }
761
    while ((csnroffst + 1) <= 63 && 
762
           bit_alloc(s, bap1, encoded_exp, exp_strategy, frame_bits, csnroffst + 1, 0) >= 0) {
763
        csnroffst++;
764
        memcpy(bap, bap1, sizeof(bap1));
765
    }
766
767
    fsnroffst = 0;
768
    while ((fsnroffst + SNR_INC1) <= 15 && 
769
           bit_alloc(s, bap1, encoded_exp, exp_strategy, frame_bits, 
770
                     csnroffst, fsnroffst + SNR_INC1) >= 0) {
771
        fsnroffst += SNR_INC1;
772
        memcpy(bap, bap1, sizeof(bap1));
773
    }
774
    while ((fsnroffst + 1) <= 15 && 
775
           bit_alloc(s, bap1, encoded_exp, exp_strategy, frame_bits, 
776
                     csnroffst, fsnroffst + 1) >= 0) {
777
        fsnroffst++;
778
        memcpy(bap, bap1, sizeof(bap1));
779
    }
780
    
781
    s->csnroffst = csnroffst;
782 30b68f33 Zdenek Kabelac
    for(ch=0;ch<s->nb_all_channels;ch++)
783 de6d9b64 Fabrice Bellard
        s->fsnroffst[ch] = fsnroffst;
784
#if defined(DEBUG_BITALLOC)
785
    {
786
        int j;
787
788
        for(i=0;i<6;i++) {
789 30b68f33 Zdenek Kabelac
            for(ch=0;ch<s->nb_all_channels;ch++) {
790 de6d9b64 Fabrice Bellard
                printf("Block #%d Ch%d:\n", i, ch);
791
                printf("bap=");
792
                for(j=0;j<s->nb_coefs[ch];j++) {
793
                    printf("%d ",bap[i][ch][j]);
794
                }
795
                printf("\n");
796
            }
797
        }
798
    }
799
#endif
800
    return 0;
801
}
802
803 6107fa87 Fabrice Bellard
void ac3_common_init(void)
804
{
805
    int i, j, k, l, v;
806
    /* compute bndtab and masktab from bandsz */
807
    k = 0;
808
    l = 0;
809
    for(i=0;i<50;i++) {
810
        bndtab[i] = l;
811
        v = bndsz[i];
812
        for(j=0;j<v;j++) masktab[k++]=i;
813
        l += v;
814
    }
815
    bndtab[50] = 0;
816
}
817
818
819 de6d9b64 Fabrice Bellard
static int AC3_encode_init(AVCodecContext *avctx)
820
{
821
    int freq = avctx->sample_rate;
822
    int bitrate = avctx->bit_rate;
823
    int channels = avctx->channels;
824
    AC3EncodeContext *s = avctx->priv_data;
825 6107fa87 Fabrice Bellard
    int i, j, ch;
826 de6d9b64 Fabrice Bellard
    float alpha;
827 0c1a9eda Zdenek Kabelac
    static const uint8_t acmod_defs[6] = {
828 30b68f33 Zdenek Kabelac
        0x01, /* C */
829
        0x02, /* L R */
830
        0x03, /* L C R */
831
        0x06, /* L R SL SR */
832
        0x07, /* L C R SL SR */
833
        0x07, /* L C R SL SR (+LFE) */
834
    };
835 de6d9b64 Fabrice Bellard
836
    avctx->frame_size = AC3_FRAME_SIZE;
837
    
838
    /* number of channels */
839 30b68f33 Zdenek Kabelac
    if (channels < 1 || channels > 6)
840
        return -1;
841
    s->acmod = acmod_defs[channels - 1];
842
    s->lfe = (channels == 6) ? 1 : 0;
843
    s->nb_all_channels = channels;
844
    s->nb_channels = channels > 5 ? 5 : channels;
845
    s->lfe_channel = s->lfe ? 5 : -1;
846 de6d9b64 Fabrice Bellard
847
    /* frequency */
848
    for(i=0;i<3;i++) {
849
        for(j=0;j<3;j++) 
850 6107fa87 Fabrice Bellard
            if ((ac3_freqs[j] >> i) == freq)
851 de6d9b64 Fabrice Bellard
                goto found;
852
    }
853
    return -1;
854
 found:    
855
    s->sample_rate = freq;
856
    s->halfratecod = i;
857
    s->fscod = j;
858
    s->bsid = 8 + s->halfratecod;
859
    s->bsmod = 0; /* complete main audio service */
860
861
    /* bitrate & frame size */
862
    bitrate /= 1000;
863
    for(i=0;i<19;i++) {
864 6107fa87 Fabrice Bellard
        if ((ac3_bitratetab[i] >> s->halfratecod) == bitrate)
865 de6d9b64 Fabrice Bellard
            break;
866
    }
867
    if (i == 19)
868
        return -1;
869
    s->bit_rate = bitrate;
870
    s->frmsizecod = i << 1;
871
    s->frame_size_min = (bitrate * 1000 * AC3_FRAME_SIZE) / (freq * 16);
872
    /* for now we do not handle fractional sizes */
873
    s->frame_size = s->frame_size_min;
874
    
875
    /* bit allocation init */
876
    for(ch=0;ch<s->nb_channels;ch++) {
877
        /* bandwidth for each channel */
878
        /* XXX: should compute the bandwidth according to the frame
879
           size, so that we avoid anoying high freq artefacts */
880
        s->chbwcod[ch] = 50; /* sample bandwidth as mpeg audio layer 2 table 0 */
881
        s->nb_coefs[ch] = ((s->chbwcod[ch] + 12) * 3) + 37;
882
    }
883 30b68f33 Zdenek Kabelac
    if (s->lfe) {
884
        s->nb_coefs[s->lfe_channel] = 7; /* fixed */
885
    }
886 de6d9b64 Fabrice Bellard
    /* initial snr offset */
887
    s->csnroffst = 40;
888
889 6107fa87 Fabrice Bellard
    ac3_common_init();
890 de6d9b64 Fabrice Bellard
891
    /* mdct init */
892
    fft_init(MDCT_NBITS - 2);
893
    for(i=0;i<N/4;i++) {
894
        alpha = 2 * M_PI * (i + 1.0 / 8.0) / (float)N;
895
        xcos1[i] = fix15(-cos(alpha));
896
        xsin1[i] = fix15(-sin(alpha));
897
    }
898
899
    ac3_crc_init();
900 492cd3a9 Michael Niedermayer
    
901
    avctx->coded_frame= avcodec_alloc_frame();
902
    avctx->coded_frame->key_frame= 1;
903 de6d9b64 Fabrice Bellard
904
    return 0;
905
}
906
907
/* output the AC3 frame header */
908
static void output_frame_header(AC3EncodeContext *s, unsigned char *frame)
909
{
910 ed7debda Alex Beregszaszi
    init_put_bits(&s->pb, frame, AC3_MAX_CODED_FRAME_SIZE);
911 de6d9b64 Fabrice Bellard
912
    put_bits(&s->pb, 16, 0x0b77); /* frame header */
913
    put_bits(&s->pb, 16, 0); /* crc1: will be filled later */
914
    put_bits(&s->pb, 2, s->fscod);
915
    put_bits(&s->pb, 6, s->frmsizecod + (s->frame_size - s->frame_size_min));
916
    put_bits(&s->pb, 5, s->bsid);
917
    put_bits(&s->pb, 3, s->bsmod);
918
    put_bits(&s->pb, 3, s->acmod);
919 30b68f33 Zdenek Kabelac
    if ((s->acmod & 0x01) && s->acmod != 0x01)
920
        put_bits(&s->pb, 2, 1); /* XXX -4.5 dB */
921
    if (s->acmod & 0x04)
922
        put_bits(&s->pb, 2, 1); /* XXX -6 dB */
923
    if (s->acmod == 0x02)
924 de6d9b64 Fabrice Bellard
        put_bits(&s->pb, 2, 0); /* surround not indicated */
925 30b68f33 Zdenek Kabelac
    put_bits(&s->pb, 1, s->lfe); /* LFE */
926 de6d9b64 Fabrice Bellard
    put_bits(&s->pb, 5, 31); /* dialog norm: -31 db */
927
    put_bits(&s->pb, 1, 0); /* no compression control word */
928
    put_bits(&s->pb, 1, 0); /* no lang code */
929
    put_bits(&s->pb, 1, 0); /* no audio production info */
930
    put_bits(&s->pb, 1, 0); /* no copyright */
931
    put_bits(&s->pb, 1, 1); /* original bitstream */
932
    put_bits(&s->pb, 1, 0); /* no time code 1 */
933
    put_bits(&s->pb, 1, 0); /* no time code 2 */
934
    put_bits(&s->pb, 1, 0); /* no addtional bit stream info */
935
}
936
937
/* symetric quantization on 'levels' levels */
938
static inline int sym_quant(int c, int e, int levels)
939
{
940
    int v;
941
942
    if (c >= 0) {
943 8d67072f Fabrice Bellard
        v = (levels * (c << e)) >> 24;
944
        v = (v + 1) >> 1;
945 de6d9b64 Fabrice Bellard
        v = (levels >> 1) + v;
946
    } else {
947 8d67072f Fabrice Bellard
        v = (levels * ((-c) << e)) >> 24;
948
        v = (v + 1) >> 1;
949 de6d9b64 Fabrice Bellard
        v = (levels >> 1) - v;
950
    }
951
    assert (v >= 0 && v < levels);
952
    return v;
953
}
954
955
/* asymetric quantization on 2^qbits levels */
956
static inline int asym_quant(int c, int e, int qbits)
957
{
958
    int lshift, m, v;
959
960
    lshift = e + qbits - 24;
961
    if (lshift >= 0)
962
        v = c << lshift;
963
    else
964
        v = c >> (-lshift);
965
    /* rounding */
966
    v = (v + 1) >> 1;
967
    m = (1 << (qbits-1));
968
    if (v >= m)
969
        v = m - 1;
970
    assert(v >= -m);
971
    return v & ((1 << qbits)-1);
972
}
973
974
/* Output one audio block. There are NB_BLOCKS audio blocks in one AC3
975
   frame */
976
static void output_audio_block(AC3EncodeContext *s,
977 0c1a9eda Zdenek Kabelac
                               uint8_t exp_strategy[AC3_MAX_CHANNELS],
978
                               uint8_t encoded_exp[AC3_MAX_CHANNELS][N/2],
979
                               uint8_t bap[AC3_MAX_CHANNELS][N/2],
980
                               int32_t mdct_coefs[AC3_MAX_CHANNELS][N/2],
981
                               int8_t global_exp[AC3_MAX_CHANNELS],
982 de6d9b64 Fabrice Bellard
                               int block_num)
983
{
984 743739d2 Michael Niedermayer
    int ch, nb_groups, group_size, i, baie, rbnd;
985 0c1a9eda Zdenek Kabelac
    uint8_t *p;
986
    uint16_t qmant[AC3_MAX_CHANNELS][N/2];
987 de6d9b64 Fabrice Bellard
    int exp0, exp1;
988
    int mant1_cnt, mant2_cnt, mant4_cnt;
989 0c1a9eda Zdenek Kabelac
    uint16_t *qmant1_ptr, *qmant2_ptr, *qmant4_ptr;
990 de6d9b64 Fabrice Bellard
    int delta0, delta1, delta2;
991
992
    for(ch=0;ch<s->nb_channels;ch++) 
993
        put_bits(&s->pb, 1, 0); /* 512 point MDCT */
994
    for(ch=0;ch<s->nb_channels;ch++) 
995
        put_bits(&s->pb, 1, 1); /* no dither */
996
    put_bits(&s->pb, 1, 0); /* no dynamic range */
997
    if (block_num == 0) {
998
        /* for block 0, even if no coupling, we must say it. This is a
999
           waste of bit :-) */
1000
        put_bits(&s->pb, 1, 1); /* coupling strategy present */
1001
        put_bits(&s->pb, 1, 0); /* no coupling strategy */
1002
    } else {
1003
        put_bits(&s->pb, 1, 0); /* no new coupling strategy */
1004
    }
1005
1006 743739d2 Michael Niedermayer
    if (s->acmod == 2)
1007
      {
1008
        if(block_num==0)
1009
          {
1010
            /* first block must define rematrixing (rematstr)  */
1011
            put_bits(&s->pb, 1, 1); 
1012
            
1013
            /* dummy rematrixing rematflg(1:4)=0 */
1014
            for (rbnd=0;rbnd<4;rbnd++)
1015
              put_bits(&s->pb, 1, 0); 
1016
          }
1017
        else 
1018
          {
1019
            /* no matrixing (but should be used in the future) */
1020
            put_bits(&s->pb, 1, 0);
1021
          } 
1022
      }
1023 de6d9b64 Fabrice Bellard
1024
#if defined(DEBUG) 
1025
    {
1026 743739d2 Michael Niedermayer
      static int count = 0;
1027 3d0ef6dd Michael Niedermayer
      av_log(NULL, AV_LOG_DEBUG, "Block #%d (%d)\n", block_num, count++);
1028 de6d9b64 Fabrice Bellard
    }
1029
#endif
1030
    /* exponent strategy */
1031
    for(ch=0;ch<s->nb_channels;ch++) {
1032
        put_bits(&s->pb, 2, exp_strategy[ch]);
1033
    }
1034
    
1035 30b68f33 Zdenek Kabelac
    if (s->lfe) {
1036
        put_bits(&s->pb, 1, exp_strategy[s->lfe_channel]);
1037
    }
1038
1039 de6d9b64 Fabrice Bellard
    for(ch=0;ch<s->nb_channels;ch++) {
1040
        if (exp_strategy[ch] != EXP_REUSE)
1041
            put_bits(&s->pb, 6, s->chbwcod[ch]);
1042
    }
1043
    
1044
    /* exponents */
1045 30b68f33 Zdenek Kabelac
    for (ch = 0; ch < s->nb_all_channels; ch++) {
1046 de6d9b64 Fabrice Bellard
        switch(exp_strategy[ch]) {
1047
        case EXP_REUSE:
1048
            continue;
1049
        case EXP_D15:
1050
            group_size = 1;
1051
            break;
1052
        case EXP_D25:
1053
            group_size = 2;
1054
            break;
1055
        default:
1056
        case EXP_D45:
1057
            group_size = 4;
1058
            break;
1059
        }
1060 30b68f33 Zdenek Kabelac
        nb_groups = (s->nb_coefs[ch] + (group_size * 3) - 4) / (3 * group_size);
1061 de6d9b64 Fabrice Bellard
        p = encoded_exp[ch];
1062
1063
        /* first exponent */
1064
        exp1 = *p++;
1065
        put_bits(&s->pb, 4, exp1);
1066
1067
        /* next ones are delta encoded */
1068
        for(i=0;i<nb_groups;i++) {
1069
            /* merge three delta in one code */
1070
            exp0 = exp1;
1071
            exp1 = p[0];
1072
            p += group_size;
1073
            delta0 = exp1 - exp0 + 2;
1074
1075
            exp0 = exp1;
1076
            exp1 = p[0];
1077
            p += group_size;
1078
            delta1 = exp1 - exp0 + 2;
1079
1080
            exp0 = exp1;
1081
            exp1 = p[0];
1082
            p += group_size;
1083
            delta2 = exp1 - exp0 + 2;
1084
1085
            put_bits(&s->pb, 7, ((delta0 * 5 + delta1) * 5) + delta2);
1086
        }
1087
1088 30b68f33 Zdenek Kabelac
        if (ch != s->lfe_channel)
1089
            put_bits(&s->pb, 2, 0); /* no gain range info */
1090 de6d9b64 Fabrice Bellard
    }
1091
1092
    /* bit allocation info */
1093
    baie = (block_num == 0);
1094
    put_bits(&s->pb, 1, baie);
1095
    if (baie) {
1096
        put_bits(&s->pb, 2, s->sdecaycod);
1097
        put_bits(&s->pb, 2, s->fdecaycod);
1098
        put_bits(&s->pb, 2, s->sgaincod);
1099
        put_bits(&s->pb, 2, s->dbkneecod);
1100
        put_bits(&s->pb, 3, s->floorcod);
1101
    }
1102
1103
    /* snr offset */
1104
    put_bits(&s->pb, 1, baie); /* always present with bai */
1105
    if (baie) {
1106
        put_bits(&s->pb, 6, s->csnroffst);
1107 30b68f33 Zdenek Kabelac
        for(ch=0;ch<s->nb_all_channels;ch++) {
1108 de6d9b64 Fabrice Bellard
            put_bits(&s->pb, 4, s->fsnroffst[ch]);
1109
            put_bits(&s->pb, 3, s->fgaincod[ch]);
1110
        }
1111
    }
1112
    
1113
    put_bits(&s->pb, 1, 0); /* no delta bit allocation */
1114
    put_bits(&s->pb, 1, 0); /* no data to skip */
1115
1116
    /* mantissa encoding : we use two passes to handle the grouping. A
1117
       one pass method may be faster, but it would necessitate to
1118
       modify the output stream. */
1119
1120
    /* first pass: quantize */
1121
    mant1_cnt = mant2_cnt = mant4_cnt = 0;
1122
    qmant1_ptr = qmant2_ptr = qmant4_ptr = NULL;
1123
1124 30b68f33 Zdenek Kabelac
    for (ch = 0; ch < s->nb_all_channels; ch++) {
1125 de6d9b64 Fabrice Bellard
        int b, c, e, v;
1126
1127
        for(i=0;i<s->nb_coefs[ch];i++) {
1128
            c = mdct_coefs[ch][i];
1129
            e = encoded_exp[ch][i] - global_exp[ch];
1130
            b = bap[ch][i];
1131
            switch(b) {
1132
            case 0:
1133
                v = 0;
1134
                break;
1135
            case 1:
1136
                v = sym_quant(c, e, 3);
1137
                switch(mant1_cnt) {
1138
                case 0:
1139
                    qmant1_ptr = &qmant[ch][i];
1140
                    v = 9 * v;
1141
                    mant1_cnt = 1;
1142
                    break;
1143
                case 1:
1144
                    *qmant1_ptr += 3 * v;
1145
                    mant1_cnt = 2;
1146
                    v = 128;
1147
                    break;
1148
                default:
1149
                    *qmant1_ptr += v;
1150
                    mant1_cnt = 0;
1151
                    v = 128;
1152
                    break;
1153
                }
1154
                break;
1155
            case 2:
1156
                v = sym_quant(c, e, 5);
1157
                switch(mant2_cnt) {
1158
                case 0:
1159
                    qmant2_ptr = &qmant[ch][i];
1160
                    v = 25 * v;
1161
                    mant2_cnt = 1;
1162
                    break;
1163
                case 1:
1164
                    *qmant2_ptr += 5 * v;
1165
                    mant2_cnt = 2;
1166
                    v = 128;
1167
                    break;
1168
                default:
1169
                    *qmant2_ptr += v;
1170
                    mant2_cnt = 0;
1171
                    v = 128;
1172
                    break;
1173
                }
1174
                break;
1175
            case 3:
1176
                v = sym_quant(c, e, 7);
1177
                break;
1178
            case 4:
1179
                v = sym_quant(c, e, 11);
1180
                switch(mant4_cnt) {
1181
                case 0:
1182
                    qmant4_ptr = &qmant[ch][i];
1183
                    v = 11 * v;
1184
                    mant4_cnt = 1;
1185
                    break;
1186
                default:
1187
                    *qmant4_ptr += v;
1188
                    mant4_cnt = 0;
1189
                    v = 128;
1190
                    break;
1191
                }
1192
                break;
1193
            case 5:
1194
                v = sym_quant(c, e, 15);
1195
                break;
1196
            case 14:
1197
                v = asym_quant(c, e, 14);
1198
                break;
1199
            case 15:
1200
                v = asym_quant(c, e, 16);
1201
                break;
1202
            default:
1203
                v = asym_quant(c, e, b - 1);
1204
                break;
1205
            }
1206
            qmant[ch][i] = v;
1207
        }
1208
    }
1209
1210
    /* second pass : output the values */
1211 30b68f33 Zdenek Kabelac
    for (ch = 0; ch < s->nb_all_channels; ch++) {
1212 de6d9b64 Fabrice Bellard
        int b, q;
1213
        
1214
        for(i=0;i<s->nb_coefs[ch];i++) {
1215
            q = qmant[ch][i];
1216
            b = bap[ch][i];
1217
            switch(b) {
1218
            case 0:
1219
                break;
1220
            case 1:
1221
                if (q != 128) 
1222
                    put_bits(&s->pb, 5, q);
1223
                break;
1224
            case 2:
1225
                if (q != 128) 
1226
                    put_bits(&s->pb, 7, q);
1227
                break;
1228
            case 3:
1229
                put_bits(&s->pb, 3, q);
1230
                break;
1231
            case 4:
1232
                if (q != 128)
1233
                    put_bits(&s->pb, 7, q);
1234
                break;
1235
            case 14:
1236
                put_bits(&s->pb, 14, q);
1237
                break;
1238
            case 15:
1239
                put_bits(&s->pb, 16, q);
1240
                break;
1241
            default:
1242
                put_bits(&s->pb, b - 1, q);
1243
                break;
1244
            }
1245
        }
1246
    }
1247
}
1248
1249
/* compute the ac3 crc */
1250
1251
#define CRC16_POLY ((1 << 0) | (1 << 2) | (1 << 15) | (1 << 16))
1252
1253
static void ac3_crc_init(void)
1254
{
1255
    unsigned int c, n, k;
1256
1257
    for(n=0;n<256;n++) {
1258
        c = n << 8;
1259
        for (k = 0; k < 8; k++) {
1260
            if (c & (1 << 15)) 
1261
                c = ((c << 1) & 0xffff) ^ (CRC16_POLY & 0xffff);
1262
            else
1263
                c = c << 1;
1264
        }
1265
        crc_table[n] = c;
1266
    }
1267
}
1268
1269 0c1a9eda Zdenek Kabelac
static unsigned int ac3_crc(uint8_t *data, int n, unsigned int crc)
1270 de6d9b64 Fabrice Bellard
{
1271
    int i;
1272
    for(i=0;i<n;i++) {
1273
        crc = (crc_table[data[i] ^ (crc >> 8)] ^ (crc << 8)) & 0xffff;
1274
    }
1275
    return crc;
1276
}
1277
1278
static unsigned int mul_poly(unsigned int a, unsigned int b, unsigned int poly)
1279
{
1280
    unsigned int c;
1281
1282
    c = 0;
1283
    while (a) {
1284
        if (a & 1)
1285
            c ^= b;
1286
        a = a >> 1;
1287
        b = b << 1;
1288
        if (b & (1 << 16))
1289
            b ^= poly;
1290
    }
1291
    return c;
1292
}
1293
1294
static unsigned int pow_poly(unsigned int a, unsigned int n, unsigned int poly)
1295
{
1296
    unsigned int r;
1297
    r = 1;
1298
    while (n) {
1299
        if (n & 1)
1300
            r = mul_poly(r, a, poly);
1301
        a = mul_poly(a, a, poly);
1302
        n >>= 1;
1303
    }
1304
    return r;
1305
}
1306
1307
1308
/* compute log2(max(abs(tab[]))) */
1309 0c1a9eda Zdenek Kabelac
static int log2_tab(int16_t *tab, int n)
1310 de6d9b64 Fabrice Bellard
{
1311
    int i, v;
1312
1313
    v = 0;
1314
    for(i=0;i<n;i++) {
1315
        v |= abs(tab[i]);
1316
    }
1317 34763c15 Fabrice Bellard
    return av_log2(v);
1318 de6d9b64 Fabrice Bellard
}
1319
1320 0c1a9eda Zdenek Kabelac
static void lshift_tab(int16_t *tab, int n, int lshift)
1321 de6d9b64 Fabrice Bellard
{
1322
    int i;
1323
1324
    if (lshift > 0) {
1325
        for(i=0;i<n;i++) {
1326
            tab[i] <<= lshift;
1327
        }
1328
    } else if (lshift < 0) {
1329
        lshift = -lshift;
1330
        for(i=0;i<n;i++) {
1331
            tab[i] >>= lshift;
1332
        }
1333
    }
1334
}
1335
1336
/* fill the end of the frame and compute the two crcs */
1337
static int output_frame_end(AC3EncodeContext *s)
1338
{
1339
    int frame_size, frame_size_58, n, crc1, crc2, crc_inv;
1340 0c1a9eda Zdenek Kabelac
    uint8_t *frame;
1341 de6d9b64 Fabrice Bellard
1342
    frame_size = s->frame_size; /* frame size in words */
1343
    /* align to 8 bits */
1344
    flush_put_bits(&s->pb);
1345
    /* add zero bytes to reach the frame size */
1346
    frame = s->pb.buf;
1347 17592475 Michael Niedermayer
    n = 2 * s->frame_size - (pbBufPtr(&s->pb) - frame) - 2;
1348 de6d9b64 Fabrice Bellard
    assert(n >= 0);
1349 743739d2 Michael Niedermayer
    if(n>0)
1350
      memset(pbBufPtr(&s->pb), 0, n);
1351 de6d9b64 Fabrice Bellard
    
1352
    /* Now we must compute both crcs : this is not so easy for crc1
1353
       because it is at the beginning of the data... */
1354
    frame_size_58 = (frame_size >> 1) + (frame_size >> 3);
1355
    crc1 = ac3_crc(frame + 4, (2 * frame_size_58) - 4, 0);
1356
    /* XXX: could precompute crc_inv */
1357
    crc_inv = pow_poly((CRC16_POLY >> 1), (16 * frame_size_58) - 16, CRC16_POLY);
1358
    crc1 = mul_poly(crc_inv, crc1, CRC16_POLY);
1359
    frame[2] = crc1 >> 8;
1360
    frame[3] = crc1;
1361
    
1362
    crc2 = ac3_crc(frame + 2 * frame_size_58, (frame_size - frame_size_58) * 2 - 2, 0);
1363
    frame[2*frame_size - 2] = crc2 >> 8;
1364
    frame[2*frame_size - 1] = crc2;
1365
1366
    //    printf("n=%d frame_size=%d\n", n, frame_size);
1367
    return frame_size * 2;
1368
}
1369
1370 6107fa87 Fabrice Bellard
static int AC3_encode_frame(AVCodecContext *avctx,
1371
                            unsigned char *frame, int buf_size, void *data)
1372 de6d9b64 Fabrice Bellard
{
1373
    AC3EncodeContext *s = avctx->priv_data;
1374
    short *samples = data;
1375
    int i, j, k, v, ch;
1376 0c1a9eda Zdenek Kabelac
    int16_t input_samples[N];
1377
    int32_t mdct_coef[NB_BLOCKS][AC3_MAX_CHANNELS][N/2];
1378
    uint8_t exp[NB_BLOCKS][AC3_MAX_CHANNELS][N/2];
1379
    uint8_t exp_strategy[NB_BLOCKS][AC3_MAX_CHANNELS];
1380
    uint8_t encoded_exp[NB_BLOCKS][AC3_MAX_CHANNELS][N/2];
1381
    uint8_t bap[NB_BLOCKS][AC3_MAX_CHANNELS][N/2];
1382
    int8_t exp_samples[NB_BLOCKS][AC3_MAX_CHANNELS];
1383 de6d9b64 Fabrice Bellard
    int frame_bits;
1384
1385
    frame_bits = 0;
1386 30b68f33 Zdenek Kabelac
    for(ch=0;ch<s->nb_all_channels;ch++) {
1387 de6d9b64 Fabrice Bellard
        /* fixed mdct to the six sub blocks & exponent computation */
1388
        for(i=0;i<NB_BLOCKS;i++) {
1389 0c1a9eda Zdenek Kabelac
            int16_t *sptr;
1390 de6d9b64 Fabrice Bellard
            int sinc;
1391
1392
            /* compute input samples */
1393 0c1a9eda Zdenek Kabelac
            memcpy(input_samples, s->last_samples[ch], N/2 * sizeof(int16_t));
1394 30b68f33 Zdenek Kabelac
            sinc = s->nb_all_channels;
1395 de6d9b64 Fabrice Bellard
            sptr = samples + (sinc * (N/2) * i) + ch;
1396
            for(j=0;j<N/2;j++) {
1397
                v = *sptr;
1398
                input_samples[j + N/2] = v;
1399
                s->last_samples[ch][j] = v; 
1400
                sptr += sinc;
1401
            }
1402
1403
            /* apply the MDCT window */
1404
            for(j=0;j<N/2;j++) {
1405
                input_samples[j] = MUL16(input_samples[j], 
1406
                                         ac3_window[j]) >> 15;
1407
                input_samples[N-j-1] = MUL16(input_samples[N-j-1], 
1408
                                             ac3_window[j]) >> 15;
1409
            }
1410
        
1411
            /* Normalize the samples to use the maximum available
1412
               precision */
1413
            v = 14 - log2_tab(input_samples, N);
1414
            if (v < 0)
1415
                v = 0;
1416
            exp_samples[i][ch] = v - 8;
1417
            lshift_tab(input_samples, N, v);
1418
1419
            /* do the MDCT */
1420
            mdct512(mdct_coef[i][ch], input_samples);
1421
            
1422
            /* compute "exponents". We take into account the
1423
               normalization there */
1424
            for(j=0;j<N/2;j++) {
1425
                int e;
1426
                v = abs(mdct_coef[i][ch][j]);
1427
                if (v == 0)
1428
                    e = 24;
1429
                else {
1430 34763c15 Fabrice Bellard
                    e = 23 - av_log2(v) + exp_samples[i][ch];
1431 de6d9b64 Fabrice Bellard
                    if (e >= 24) {
1432
                        e = 24;
1433
                        mdct_coef[i][ch][j] = 0;
1434
                    }
1435
                }
1436
                exp[i][ch][j] = e;
1437
            }
1438
        }
1439
        
1440 30b68f33 Zdenek Kabelac
        compute_exp_strategy(exp_strategy, exp, ch, ch == s->lfe_channel);
1441 de6d9b64 Fabrice Bellard
1442
        /* compute the exponents as the decoder will see them. The
1443
           EXP_REUSE case must be handled carefully : we select the
1444
           min of the exponents */
1445
        i = 0;
1446
        while (i < NB_BLOCKS) {
1447
            j = i + 1;
1448
            while (j < NB_BLOCKS && exp_strategy[j][ch] == EXP_REUSE) {
1449
                exponent_min(exp[i][ch], exp[j][ch], s->nb_coefs[ch]);
1450
                j++;
1451
            }
1452
            frame_bits += encode_exp(encoded_exp[i][ch],
1453
                                     exp[i][ch], s->nb_coefs[ch], 
1454
                                     exp_strategy[i][ch]);
1455
            /* copy encoded exponents for reuse case */
1456
            for(k=i+1;k<j;k++) {
1457
                memcpy(encoded_exp[k][ch], encoded_exp[i][ch], 
1458 0c1a9eda Zdenek Kabelac
                       s->nb_coefs[ch] * sizeof(uint8_t));
1459 de6d9b64 Fabrice Bellard
            }
1460
            i = j;
1461
        }
1462
    }
1463
1464
    compute_bit_allocation(s, bap, encoded_exp, exp_strategy, frame_bits);
1465
    /* everything is known... let's output the frame */
1466
    output_frame_header(s, frame);
1467
        
1468
    for(i=0;i<NB_BLOCKS;i++) {
1469
        output_audio_block(s, exp_strategy[i], encoded_exp[i], 
1470
                           bap[i], mdct_coef[i], exp_samples[i], i);
1471
    }
1472
    return output_frame_end(s);
1473
}
1474
1475 492cd3a9 Michael Niedermayer
static int AC3_encode_close(AVCodecContext *avctx)
1476
{
1477
    av_freep(&avctx->coded_frame);
1478 ef9f7306 Måns Rullgård
    return 0;
1479 492cd3a9 Michael Niedermayer
}
1480
1481 de6d9b64 Fabrice Bellard
#if 0
1482
/*************************************************************************/
1483
/* TEST */
1484

1485
#define FN (N/4)
1486

1487
void fft_test(void)
1488
{
1489
    IComplex in[FN], in1[FN];
1490
    int k, n, i;
1491
    float sum_re, sum_im, a;
1492

1493
    /* FFT test */
1494

1495
    for(i=0;i<FN;i++) {
1496
        in[i].re = random() % 65535 - 32767;
1497
        in[i].im = random() % 65535 - 32767;
1498
        in1[i] = in[i];
1499
    }
1500
    fft(in, 7);
1501

1502
    /* do it by hand */
1503
    for(k=0;k<FN;k++) {
1504
        sum_re = 0;
1505
        sum_im = 0;
1506
        for(n=0;n<FN;n++) {
1507
            a = -2 * M_PI * (n * k) / FN;
1508
            sum_re += in1[n].re * cos(a) - in1[n].im * sin(a);
1509
            sum_im += in1[n].re * sin(a) + in1[n].im * cos(a);
1510
        }
1511
        printf("%3d: %6d,%6d %6.0f,%6.0f\n", 
1512
               k, in[k].re, in[k].im, sum_re / FN, sum_im / FN); 
1513
    }
1514
}
1515

1516
void mdct_test(void)
1517
{
1518 0c1a9eda Zdenek Kabelac
    int16_t input[N];
1519
    int32_t output[N/2];
1520 de6d9b64 Fabrice Bellard
    float input1[N];
1521
    float output1[N/2];
1522
    float s, a, err, e, emax;
1523
    int i, k, n;
1524

1525
    for(i=0;i<N;i++) {
1526
        input[i] = (random() % 65535 - 32767) * 9 / 10;
1527
        input1[i] = input[i];
1528
    }
1529

1530
    mdct512(output, input);
1531
    
1532
    /* do it by hand */
1533
    for(k=0;k<N/2;k++) {
1534
        s = 0;
1535
        for(n=0;n<N;n++) {
1536
            a = (2*M_PI*(2*n+1+N/2)*(2*k+1) / (4 * N));
1537
            s += input1[n] * cos(a);
1538
        }
1539
        output1[k] = -2 * s / N;
1540
    }
1541
    
1542
    err = 0;
1543
    emax = 0;
1544
    for(i=0;i<N/2;i++) {
1545
        printf("%3d: %7d %7.0f\n", i, output[i], output1[i]);
1546
        e = output[i] - output1[i];
1547
        if (e > emax)
1548
            emax = e;
1549
        err += e * e;
1550
    }
1551
    printf("err2=%f emax=%f\n", err / (N/2), emax);
1552
}
1553

1554
void test_ac3(void)
1555
{
1556
    AC3EncodeContext ctx;
1557
    unsigned char frame[AC3_MAX_CODED_FRAME_SIZE];
1558
    short samples[AC3_FRAME_SIZE];
1559
    int ret, i;
1560
    
1561
    AC3_encode_init(&ctx, 44100, 64000, 1);
1562

1563
    fft_test();
1564
    mdct_test();
1565

1566
    for(i=0;i<AC3_FRAME_SIZE;i++)
1567
        samples[i] = (int)(sin(2*M_PI*i*1000.0/44100) * 10000);
1568
    ret = AC3_encode_frame(&ctx, frame, samples);
1569
    printf("ret=%d\n", ret);
1570
}
1571
#endif
1572
1573
AVCodec ac3_encoder = {
1574
    "ac3",
1575
    CODEC_TYPE_AUDIO,
1576
    CODEC_ID_AC3,
1577
    sizeof(AC3EncodeContext),
1578
    AC3_encode_init,
1579
    AC3_encode_frame,
1580 492cd3a9 Michael Niedermayer
    AC3_encode_close,
1581 de6d9b64 Fabrice Bellard
    NULL,
1582
};