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1
/*
2
 * The simplest AC-3 encoder
3
 * Copyright (c) 2000 Fabrice Bellard
4
 *
5
 * This file is part of FFmpeg.
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 *
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 * 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.
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 *
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 * FFmpeg is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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
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 * The simplest AC-3 encoder.
25
 */
26

    
27
//#define DEBUG
28

    
29
#include "libavcore/audioconvert.h"
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#include "libavutil/crc.h"
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#include "avcodec.h"
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#include "put_bits.h"
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#include "ac3.h"
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#include "audioconvert.h"
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36

    
37
#define MDCT_NBITS 9
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#define MDCT_SAMPLES (1 << MDCT_NBITS)
39

    
40
/** Maximum number of exponent groups. +1 for separate DC exponent. */
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#define AC3_MAX_EXP_GROUPS 85
42

    
43
/** Scale a float value by 2^bits and convert to an integer. */
44
#define SCALE_FLOAT(a, bits) lrintf((a) * (float)(1 << (bits)))
45

    
46
/** Scale a float value by 2^15, convert to an integer, and clip to int16_t range. */
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#define FIX15(a) av_clip_int16(SCALE_FLOAT(a, 15))
48

    
49

    
50
/**
51
 * Compex number.
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 * Used in fixed-point MDCT calculation.
53
 */
54
typedef struct IComplex {
55
    int16_t re,im;
56
} IComplex;
57

    
58
/**
59
 * AC-3 encoder private context.
60
 */
61
typedef struct AC3EncodeContext {
62
    PutBitContext pb;                       ///< bitstream writer context
63

    
64
    int bitstream_id;                       ///< bitstream id                           (bsid)
65
    int bitstream_mode;                     ///< bitstream mode                         (bsmod)
66

    
67
    int bit_rate;                           ///< target bit rate, in bits-per-second
68
    int sample_rate;                        ///< sampling frequency, in Hz
69

    
70
    int frame_size_min;                     ///< minimum frame size in case rounding is necessary
71
    int frame_size;                         ///< current frame size in bytes
72
    int frame_size_code;                    ///< frame size code                        (frmsizecod)
73
    int bits_written;                       ///< bit count    (used to avg. bitrate)
74
    int samples_written;                    ///< sample count (used to avg. bitrate)
75

    
76
    int fbw_channels;                       ///< number of full-bandwidth channels      (nfchans)
77
    int channels;                           ///< total number of channels               (nchans)
78
    int lfe_on;                             ///< indicates if there is an LFE channel   (lfeon)
79
    int lfe_channel;                        ///< channel index of the LFE channel
80
    int channel_mode;                       ///< channel mode                           (acmod)
81
    const uint8_t *channel_map;             ///< channel map used to reorder channels
82

    
83
    int bandwidth_code[AC3_MAX_CHANNELS];   ///< bandwidth code (0 to 60)               (chbwcod)
84
    int nb_coefs[AC3_MAX_CHANNELS];
85

    
86
    /* bitrate allocation control */
87
    int slow_gain_code;                     ///< slow gain code                         (sgaincod)
88
    int slow_decay_code;                    ///< slow decay code                        (sdcycod)
89
    int fast_decay_code;                    ///< fast decay code                        (fdcycod)
90
    int db_per_bit_code;                    ///< dB/bit code                            (dbpbcod)
91
    int floor_code;                         ///< floor code                             (floorcod)
92
    AC3BitAllocParameters bit_alloc;        ///< bit allocation parameters
93
    int coarse_snr_offset;                  ///< coarse SNR offsets                     (csnroffst)
94
    int fast_gain_code[AC3_MAX_CHANNELS];   ///< fast gain codes (signal-to-mask ratio) (fgaincod)
95
    int fine_snr_offset[AC3_MAX_CHANNELS];  ///< fine SNR offsets                       (fsnroffst)
96
    int frame_bits;                         ///< all frame bits except exponents and mantissas
97
    int exponent_bits;                      ///< number of bits used for exponents
98

    
99
    /* mantissa encoding */
100
    int mant1_cnt, mant2_cnt, mant4_cnt;    ///< mantissa counts for bap=1,2,4
101
    uint16_t *qmant1_ptr, *qmant2_ptr, *qmant4_ptr; ///< mantissa pointers for bap=1,2,4
102

    
103
    int16_t last_samples[AC3_MAX_CHANNELS][AC3_BLOCK_SIZE]; ///< last 256 samples from previous frame
104
} AC3EncodeContext;
105

    
106

    
107
/** MDCT and FFT tables */
108
static int16_t costab[64];
109
static int16_t sintab[64];
110
static int16_t xcos1[128];
111
static int16_t xsin1[128];
112

    
113

    
114
/**
115
 * Adjust the frame size to make the average bit rate match the target bit rate.
116
 * This is only needed for 11025, 22050, and 44100 sample rates.
117
 */
118
static void adjust_frame_size(AC3EncodeContext *s)
119
{
120
    while (s->bits_written >= s->bit_rate && s->samples_written >= s->sample_rate) {
121
        s->bits_written    -= s->bit_rate;
122
        s->samples_written -= s->sample_rate;
123
    }
124
    s->frame_size = s->frame_size_min + 2 * (s->bits_written * s->sample_rate < s->samples_written * s->bit_rate);
125
    s->bits_written    += s->frame_size * 8;
126
    s->samples_written += AC3_FRAME_SIZE;
127
}
128

    
129

    
130
/**
131
 * Deinterleave input samples.
132
 * Channels are reordered from FFmpeg's default order to AC-3 order.
133
 */
134
static void deinterleave_input_samples(AC3EncodeContext *s,
135
                                       const int16_t *samples,
136
                                       int16_t planar_samples[AC3_MAX_CHANNELS][AC3_BLOCK_SIZE+AC3_FRAME_SIZE])
137
{
138
    int ch, i;
139

    
140
    /* deinterleave and remap input samples */
141
    for (ch = 0; ch < s->channels; ch++) {
142
        const int16_t *sptr;
143
        int sinc;
144

    
145
        /* copy last 256 samples of previous frame to the start of the current frame */
146
        memcpy(&planar_samples[ch][0], s->last_samples[ch],
147
               AC3_BLOCK_SIZE * sizeof(planar_samples[0][0]));
148

    
149
        /* deinterleave */
150
        sinc = s->channels;
151
        sptr = samples + s->channel_map[ch];
152
        for (i = AC3_BLOCK_SIZE; i < AC3_FRAME_SIZE+AC3_BLOCK_SIZE; i++) {
153
            planar_samples[ch][i] = *sptr;
154
            sptr += sinc;
155
        }
156

    
157
        /* save last 256 samples for next frame */
158
        memcpy(s->last_samples[ch], &planar_samples[ch][6* AC3_BLOCK_SIZE],
159
               AC3_BLOCK_SIZE * sizeof(planar_samples[0][0]));
160
    }
161
}
162

    
163

    
164
/**
165
 * Initialize FFT tables.
166
 * @param ln log2(FFT size)
167
 */
168
static av_cold void fft_init(int ln)
169
{
170
    int i, n, n2;
171
    float alpha;
172

    
173
    n  = 1 << ln;
174
    n2 = n >> 1;
175

    
176
    for (i = 0; i < n2; i++) {
177
        alpha     = 2.0 * M_PI * i / n;
178
        costab[i] = FIX15(cos(alpha));
179
        sintab[i] = FIX15(sin(alpha));
180
    }
181
}
182

    
183

    
184
/**
185
 * Initialize MDCT tables.
186
 * @param nbits log2(MDCT size)
187
 */
188
static av_cold void mdct_init(int nbits)
189
{
190
    int i, n, n4;
191

    
192
    n  = 1 << nbits;
193
    n4 = n >> 2;
194

    
195
    fft_init(nbits - 2);
196

    
197
    for (i = 0; i < n4; i++) {
198
        float alpha = 2.0 * M_PI * (i + 1.0 / 8.0) / n;
199
        xcos1[i] = FIX15(-cos(alpha));
200
        xsin1[i] = FIX15(-sin(alpha));
201
    }
202
}
203

    
204

    
205
/** Butterfly op */
206
#define BF(pre, pim, qre, qim, pre1, pim1, qre1, qim1)  \
207
{                                                       \
208
  int ax, ay, bx, by;                                   \
209
  bx  = pre1;                                           \
210
  by  = pim1;                                           \
211
  ax  = qre1;                                           \
212
  ay  = qim1;                                           \
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  pre = (bx + ax) >> 1;                                 \
214
  pim = (by + ay) >> 1;                                 \
215
  qre = (bx - ax) >> 1;                                 \
216
  qim = (by - ay) >> 1;                                 \
217
}
218

    
219

    
220
/** Complex multiply */
221
#define CMUL(pre, pim, are, aim, bre, bim)              \
222
{                                                       \
223
   pre = (MUL16(are, bre) - MUL16(aim, bim)) >> 15;     \
224
   pim = (MUL16(are, bim) + MUL16(bre, aim)) >> 15;     \
225
}
226

    
227

    
228
/**
229
 * Calculate a 2^n point complex FFT on 2^ln points.
230
 * @param z  complex input/output samples
231
 * @param ln log2(FFT size)
232
 */
233
static void fft(IComplex *z, int ln)
234
{
235
    int j, l, np, np2;
236
    int nblocks, nloops;
237
    register IComplex *p,*q;
238
    int tmp_re, tmp_im;
239

    
240
    np = 1 << ln;
241

    
242
    /* reverse */
243
    for (j = 0; j < np; j++) {
244
        int k = av_reverse[j] >> (8 - ln);
245
        if (k < j)
246
            FFSWAP(IComplex, z[k], z[j]);
247
    }
248

    
249
    /* pass 0 */
250

    
251
    p = &z[0];
252
    j = np >> 1;
253
    do {
254
        BF(p[0].re, p[0].im, p[1].re, p[1].im,
255
           p[0].re, p[0].im, p[1].re, p[1].im);
256
        p += 2;
257
    } while (--j);
258

    
259
    /* pass 1 */
260

    
261
    p = &z[0];
262
    j = np >> 2;
263
    do {
264
        BF(p[0].re, p[0].im, p[2].re,  p[2].im,
265
           p[0].re, p[0].im, p[2].re,  p[2].im);
266
        BF(p[1].re, p[1].im, p[3].re,  p[3].im,
267
           p[1].re, p[1].im, p[3].im, -p[3].re);
268
        p+=4;
269
    } while (--j);
270

    
271
    /* pass 2 .. ln-1 */
272

    
273
    nblocks = np >> 3;
274
    nloops  =  1 << 2;
275
    np2     = np >> 1;
276
    do {
277
        p = z;
278
        q = z + nloops;
279
        for (j = 0; j < nblocks; j++) {
280
            BF(p->re, p->im, q->re, q->im,
281
               p->re, p->im, q->re, q->im);
282
            p++;
283
            q++;
284
            for(l = nblocks; l < np2; l += nblocks) {
285
                CMUL(tmp_re, tmp_im, costab[l], -sintab[l], q->re, q->im);
286
                BF(p->re, p->im, q->re,  q->im,
287
                   p->re, p->im, tmp_re, tmp_im);
288
                p++;
289
                q++;
290
            }
291
            p += nloops;
292
            q += nloops;
293
        }
294
        nblocks = nblocks >> 1;
295
        nloops  = nloops  << 1;
296
    } while (nblocks);
297
}
298

    
299

    
300
/**
301
 * Calculate a 512-point MDCT
302
 * @param out 256 output frequency coefficients
303
 * @param in  512 windowed input audio samples
304
 */
305
static void mdct512(int32_t *out, int16_t *in)
306
{
307
    int i, re, im, re1, im1;
308
    int16_t rot[MDCT_SAMPLES];
309
    IComplex x[MDCT_SAMPLES/4];
310

    
311
    /* shift to simplify computations */
312
    for (i = 0; i < MDCT_SAMPLES/4; i++)
313
        rot[i] = -in[i + 3*MDCT_SAMPLES/4];
314
    for (;i < MDCT_SAMPLES; i++)
315
        rot[i] =  in[i -   MDCT_SAMPLES/4];
316

    
317
    /* pre rotation */
318
    for (i = 0; i < MDCT_SAMPLES/4; i++) {
319
        re =  ((int)rot[               2*i] - (int)rot[MDCT_SAMPLES  -1-2*i]) >> 1;
320
        im = -((int)rot[MDCT_SAMPLES/2+2*i] - (int)rot[MDCT_SAMPLES/2-1-2*i]) >> 1;
321
        CMUL(x[i].re, x[i].im, re, im, -xcos1[i], xsin1[i]);
322
    }
323

    
324
    fft(x, MDCT_NBITS - 2);
325

    
326
    /* post rotation */
327
    for (i = 0; i < MDCT_SAMPLES/4; i++) {
328
        re = x[i].re;
329
        im = x[i].im;
330
        CMUL(re1, im1, re, im, xsin1[i], xcos1[i]);
331
        out[                 2*i] = im1;
332
        out[MDCT_SAMPLES/2-1-2*i] = re1;
333
    }
334
}
335

    
336

    
337
/**
338
 * Apply KBD window to input samples prior to MDCT.
339
 */
340
static void apply_window(int16_t *output, const int16_t *input,
341
                         const int16_t *window, int n)
342
{
343
    int i;
344
    int n2 = n >> 1;
345

    
346
    for (i = 0; i < n2; i++) {
347
        output[i]     = MUL16(input[i],     window[i]) >> 15;
348
        output[n-i-1] = MUL16(input[n-i-1], window[i]) >> 15;
349
    }
350
}
351

    
352

    
353
/**
354
 * Calculate the log2() of the maximum absolute value in an array.
355
 * @param tab input array
356
 * @param n   number of values in the array
357
 * @return    log2(max(abs(tab[])))
358
 */
359
static int log2_tab(int16_t *tab, int n)
360
{
361
    int i, v;
362

    
363
    v = 0;
364
    for (i = 0; i < n; i++)
365
        v |= abs(tab[i]);
366

    
367
    return av_log2(v);
368
}
369

    
370

    
371
/**
372
 * Left-shift each value in an array by a specified amount.
373
 * @param tab    input array
374
 * @param n      number of values in the array
375
 * @param lshift left shift amount. a negative value means right shift.
376
 */
377
static void lshift_tab(int16_t *tab, int n, int lshift)
378
{
379
    int i;
380

    
381
    if (lshift > 0) {
382
        for(i = 0; i < n; i++)
383
            tab[i] <<= lshift;
384
    } else if (lshift < 0) {
385
        lshift = -lshift;
386
        for (i = 0; i < n; i++)
387
            tab[i] >>= lshift;
388
    }
389
}
390

    
391

    
392
/**
393
 * Normalize the input samples to use the maximum available precision.
394
 * This assumes signed 16-bit input samples. Exponents are reduced by 9 to
395
 * match the 24-bit internal precision for MDCT coefficients.
396
 *
397
 * @return exponent shift
398
 */
399
static int normalize_samples(AC3EncodeContext *s,
400
                             int16_t windowed_samples[AC3_WINDOW_SIZE])
401
{
402
    int v = 14 - log2_tab(windowed_samples, AC3_WINDOW_SIZE);
403
    v = FFMAX(0, v);
404
    lshift_tab(windowed_samples, AC3_WINDOW_SIZE, v);
405
    return v - 9;
406
}
407

    
408

    
409
/**
410
 * Apply the MDCT to input samples to generate frequency coefficients.
411
 * This applies the KBD window and normalizes the input to reduce precision
412
 * loss due to fixed-point calculations.
413
 */
414
static void apply_mdct(AC3EncodeContext *s,
415
                       int16_t planar_samples[AC3_MAX_CHANNELS][AC3_BLOCK_SIZE+AC3_FRAME_SIZE],
416
                       int8_t exp_shift[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS],
417
                       int32_t mdct_coef[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS])
418
{
419
    int blk, ch;
420
    int16_t windowed_samples[AC3_WINDOW_SIZE];
421

    
422
    for (ch = 0; ch < s->channels; ch++) {
423
        for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
424
            const int16_t *input_samples = &planar_samples[ch][blk * AC3_BLOCK_SIZE];
425

    
426
            apply_window(windowed_samples, input_samples, ff_ac3_window, AC3_WINDOW_SIZE);
427

    
428
            exp_shift[blk][ch] = normalize_samples(s, windowed_samples);
429

    
430
            mdct512(mdct_coef[blk][ch], windowed_samples);
431
        }
432
    }
433
}
434

    
435

    
436
/**
437
 * Extract exponents from the MDCT coefficients.
438
 * This takes into account the normalization that was done to the input samples
439
 * by adjusting the exponents by the exponent shift values.
440
 */
441
static void extract_exponents(AC3EncodeContext *s,
442
                              int32_t mdct_coef[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS],
443
                              int8_t exp_shift[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS],
444
                              uint8_t exp[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS])
445
{
446
    int blk, ch, i;
447

    
448
    /* extract exponents */
449
    for (ch = 0; ch < s->channels; ch++) {
450
        for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
451
            /* compute "exponents". We take into account the normalization there */
452
            for (i = 0; i < AC3_MAX_COEFS; i++) {
453
                int e;
454
                int v = abs(mdct_coef[blk][ch][i]);
455
                if (v == 0)
456
                    e = 24;
457
                else {
458
                    e = 23 - av_log2(v) + exp_shift[blk][ch];
459
                    if (e >= 24) {
460
                        e = 24;
461
                        mdct_coef[blk][ch][i] = 0;
462
                    }
463
                }
464
                exp[blk][ch][i] = e;
465
            }
466
        }
467
    }
468
}
469

    
470

    
471
/**
472
 * Calculate the sum of absolute differences (SAD) between 2 sets of exponents.
473
 */
474
static int calc_exp_diff(uint8_t *exp1, uint8_t *exp2, int n)
475
{
476
    int sum, i;
477
    sum = 0;
478
    for (i = 0; i < n; i++)
479
        sum += abs(exp1[i] - exp2[i]);
480
    return sum;
481
}
482

    
483

    
484
/**
485
 * Exponent Difference Threshold.
486
 * New exponents are sent if their SAD exceed this number.
487
 */
488
#define EXP_DIFF_THRESHOLD 1000
489

    
490

    
491
/**
492
 * Calculate exponent strategies for all blocks in a single channel.
493
 */
494
static void compute_exp_strategy_ch(uint8_t *exp_strategy, uint8_t **exp)
495
{
496
    int blk, blk1;
497
    int exp_diff;
498

    
499
    /* estimate if the exponent variation & decide if they should be
500
       reused in the next frame */
501
    exp_strategy[0] = EXP_NEW;
502
    for (blk = 1; blk < AC3_MAX_BLOCKS; blk++) {
503
        exp_diff = calc_exp_diff(exp[blk], exp[blk-1], AC3_MAX_COEFS);
504
        if (exp_diff > EXP_DIFF_THRESHOLD)
505
            exp_strategy[blk] = EXP_NEW;
506
        else
507
            exp_strategy[blk] = EXP_REUSE;
508
    }
509

    
510
    /* now select the encoding strategy type : if exponents are often
511
       recoded, we use a coarse encoding */
512
    blk = 0;
513
    while (blk < AC3_MAX_BLOCKS) {
514
        blk1 = blk + 1;
515
        while (blk1 < AC3_MAX_BLOCKS && exp_strategy[blk1] == EXP_REUSE)
516
            blk1++;
517
        switch (blk1 - blk) {
518
        case 1:  exp_strategy[blk] = EXP_D45; break;
519
        case 2:
520
        case 3:  exp_strategy[blk] = EXP_D25; break;
521
        default: exp_strategy[blk] = EXP_D15; break;
522
        }
523
        blk = blk1;
524
    }
525
}
526

    
527

    
528
/**
529
 * Calculate exponent strategies for all channels.
530
 * Array arrangement is reversed to simplify the per-channel calculation.
531
 */
532
static void compute_exp_strategy(AC3EncodeContext *s,
533
                                 uint8_t exp_strategy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS],
534
                                 uint8_t exp[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS])
535
{
536
    uint8_t *exp1[AC3_MAX_CHANNELS][AC3_MAX_BLOCKS];
537
    uint8_t exp_str1[AC3_MAX_CHANNELS][AC3_MAX_BLOCKS];
538
    int ch, blk;
539

    
540
    for (ch = 0; ch < s->fbw_channels; ch++) {
541
        for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
542
            exp1[ch][blk]     = exp[blk][ch];
543
            exp_str1[ch][blk] = exp_strategy[blk][ch];
544
        }
545

    
546
        compute_exp_strategy_ch(exp_str1[ch], exp1[ch]);
547

    
548
        for (blk = 0; blk < AC3_MAX_BLOCKS; blk++)
549
            exp_strategy[blk][ch] = exp_str1[ch][blk];
550
    }
551
    if (s->lfe_on) {
552
        ch = s->lfe_channel;
553
        exp_strategy[0][ch] = EXP_D15;
554
        for (blk = 1; blk < 5; blk++)
555
            exp_strategy[blk][ch] = EXP_REUSE;
556
    }
557
}
558

    
559

    
560
/**
561
 * Set each encoded exponent in a block to the minimum of itself and the
562
 * exponent in the same frequency bin of a following block.
563
 * exp[i] = min(exp[i], exp1[i]
564
 */
565
static void exponent_min(uint8_t exp[AC3_MAX_COEFS], uint8_t exp1[AC3_MAX_COEFS], int n)
566
{
567
    int i;
568
    for (i = 0; i < n; i++) {
569
        if (exp1[i] < exp[i])
570
            exp[i] = exp1[i];
571
    }
572
}
573

    
574

    
575
/**
576
 * Update the exponents so that they are the ones the decoder will decode.
577
 */
578
static void encode_exponents_blk_ch(uint8_t encoded_exp[AC3_MAX_COEFS],
579
                                    uint8_t exp[AC3_MAX_COEFS],
580
                                    int nb_exps, int exp_strategy,
581
                                    uint8_t *num_exp_groups)
582
{
583
    int group_size, nb_groups, i, j, k, exp_min;
584
    uint8_t exp1[AC3_MAX_COEFS];
585

    
586
    group_size = exp_strategy + (exp_strategy == EXP_D45);
587
    *num_exp_groups = (nb_exps + (group_size * 3) - 4) / (3 * group_size);
588
    nb_groups = *num_exp_groups * 3;
589

    
590
    /* for each group, compute the minimum exponent */
591
    exp1[0] = exp[0]; /* DC exponent is handled separately */
592
    k = 1;
593
    for (i = 1; i <= nb_groups; i++) {
594
        exp_min = exp[k];
595
        assert(exp_min >= 0 && exp_min <= 24);
596
        for (j = 1; j < group_size; j++) {
597
            if (exp[k+j] < exp_min)
598
                exp_min = exp[k+j];
599
        }
600
        exp1[i] = exp_min;
601
        k += group_size;
602
    }
603

    
604
    /* constraint for DC exponent */
605
    if (exp1[0] > 15)
606
        exp1[0] = 15;
607

    
608
    /* decrease the delta between each groups to within 2 so that they can be
609
       differentially encoded */
610
    for (i = 1; i <= nb_groups; i++)
611
        exp1[i] = FFMIN(exp1[i], exp1[i-1] + 2);
612
    for (i = nb_groups-1; i >= 0; i--)
613
        exp1[i] = FFMIN(exp1[i], exp1[i+1] + 2);
614

    
615
    /* now we have the exponent values the decoder will see */
616
    encoded_exp[0] = exp1[0];
617
    k = 1;
618
    for (i = 1; i <= nb_groups; i++) {
619
        for (j = 0; j < group_size; j++)
620
            encoded_exp[k+j] = exp1[i];
621
        k += group_size;
622
    }
623
}
624

    
625

    
626
/**
627
 * Encode exponents from original extracted form to what the decoder will see.
628
 * This copies and groups exponents based on exponent strategy and reduces
629
 * deltas between adjacent exponent groups so that they can be differentially
630
 * encoded.
631
 */
632
static void encode_exponents(AC3EncodeContext *s,
633
                             uint8_t exp[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS],
634
                             uint8_t exp_strategy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS],
635
                             uint8_t num_exp_groups[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS],
636
                             uint8_t encoded_exp[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS])
637
{
638
    int blk, blk1, blk2, ch;
639

    
640
    for (ch = 0; ch < s->channels; ch++) {
641
        /* for the EXP_REUSE case we select the min of the exponents */
642
        blk = 0;
643
        while (blk < AC3_MAX_BLOCKS) {
644
            blk1 = blk + 1;
645
            while (blk1 < AC3_MAX_BLOCKS && exp_strategy[blk1][ch] == EXP_REUSE) {
646
                exponent_min(exp[blk][ch], exp[blk1][ch], s->nb_coefs[ch]);
647
                blk1++;
648
            }
649
            encode_exponents_blk_ch(encoded_exp[blk][ch],
650
                                    exp[blk][ch], s->nb_coefs[ch],
651
                                    exp_strategy[blk][ch],
652
                                    &num_exp_groups[blk][ch]);
653
            /* copy encoded exponents for reuse case */
654
            for (blk2 = blk+1; blk2 < blk1; blk2++) {
655
                memcpy(encoded_exp[blk2][ch], encoded_exp[blk][ch],
656
                       s->nb_coefs[ch] * sizeof(uint8_t));
657
            }
658
            blk = blk1;
659
        }
660
    }
661
}
662

    
663

    
664
/**
665
 * Group exponents.
666
 * 3 delta-encoded exponents are in each 7-bit group. The number of groups
667
 * varies depending on exponent strategy and bandwidth.
668
 */
669
static void group_exponents(AC3EncodeContext *s,
670
                            uint8_t encoded_exp[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS],
671
                            uint8_t exp_strategy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS],
672
                            uint8_t num_exp_groups[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS],
673
                            uint8_t grouped_exp[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_EXP_GROUPS])
674
{
675
    int blk, ch, i;
676
    int group_size, bit_count;
677
    uint8_t *p;
678
    int delta0, delta1, delta2;
679
    int exp0, exp1;
680

    
681
    bit_count = 0;
682
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
683
        for (ch = 0; ch < s->channels; ch++) {
684
            if (exp_strategy[blk][ch] == EXP_REUSE) {
685
                num_exp_groups[blk][ch] = 0;
686
                continue;
687
            }
688
            group_size = exp_strategy[blk][ch] + (exp_strategy[blk][ch] == EXP_D45);
689
            bit_count += 4 + (num_exp_groups[blk][ch] * 7);
690
            p = encoded_exp[blk][ch];
691

    
692
            /* DC exponent */
693
            exp1 = *p++;
694
            grouped_exp[blk][ch][0] = exp1;
695

    
696
            /* remaining exponents are delta encoded */
697
            for (i = 1; i <= num_exp_groups[blk][ch]; i++) {
698
                /* merge three delta in one code */
699
                exp0   = exp1;
700
                exp1   = p[0];
701
                p     += group_size;
702
                delta0 = exp1 - exp0 + 2;
703

    
704
                exp0   = exp1;
705
                exp1   = p[0];
706
                p     += group_size;
707
                delta1 = exp1 - exp0 + 2;
708

    
709
                exp0   = exp1;
710
                exp1   = p[0];
711
                p     += group_size;
712
                delta2 = exp1 - exp0 + 2;
713

    
714
                grouped_exp[blk][ch][i] = ((delta0 * 5 + delta1) * 5) + delta2;
715
            }
716
        }
717
    }
718

    
719
    s->exponent_bits = bit_count;
720
}
721

    
722

    
723
/**
724
 * Calculate final exponents from the supplied MDCT coefficients and exponent shift.
725
 * Extract exponents from MDCT coefficients, calculate exponent strategies,
726
 * and encode final exponents.
727
 */
728
static void process_exponents(AC3EncodeContext *s,
729
                              int32_t mdct_coef[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS],
730
                              int8_t exp_shift[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS],
731
                              uint8_t exp[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS],
732
                              uint8_t exp_strategy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS],
733
                              uint8_t encoded_exp[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS],
734
                              uint8_t num_exp_groups[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS],
735
                              uint8_t grouped_exp[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_EXP_GROUPS])
736
{
737
    extract_exponents(s, mdct_coef, exp_shift, exp);
738

    
739
    compute_exp_strategy(s, exp_strategy, exp);
740

    
741
    encode_exponents(s, exp, exp_strategy, num_exp_groups, encoded_exp);
742

    
743
    group_exponents(s, encoded_exp, exp_strategy, num_exp_groups, grouped_exp);
744
}
745

    
746

    
747
/**
748
 * Initialize bit allocation.
749
 * Set default parameter codes and calculate parameter values.
750
 */
751
static void bit_alloc_init(AC3EncodeContext *s)
752
{
753
    int ch;
754

    
755
    /* init default parameters */
756
    s->slow_decay_code = 2;
757
    s->fast_decay_code = 1;
758
    s->slow_gain_code  = 1;
759
    s->db_per_bit_code = 2;
760
    s->floor_code      = 4;
761
    for (ch = 0; ch < s->channels; ch++)
762
        s->fast_gain_code[ch] = 4;
763

    
764
    /* initial snr offset */
765
    s->coarse_snr_offset = 40;
766

    
767
    /* compute real values */
768
    /* currently none of these values change during encoding, so we can just
769
       set them once at initialization */
770
    s->bit_alloc.slow_decay = ff_ac3_slow_decay_tab[s->slow_decay_code] >> s->bit_alloc.sr_shift;
771
    s->bit_alloc.fast_decay = ff_ac3_fast_decay_tab[s->fast_decay_code] >> s->bit_alloc.sr_shift;
772
    s->bit_alloc.slow_gain  = ff_ac3_slow_gain_tab[s->slow_gain_code];
773
    s->bit_alloc.db_per_bit = ff_ac3_db_per_bit_tab[s->db_per_bit_code];
774
    s->bit_alloc.floor      = ff_ac3_floor_tab[s->floor_code];
775
}
776

    
777

    
778
/**
779
 * Count the bits used to encode the frame, minus exponents and mantissas.
780
 */
781
static void count_frame_bits(AC3EncodeContext *s,
782
                             uint8_t exp_strategy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS])
783
{
784
    static const int frame_bits_inc[8] = { 0, 0, 2, 2, 2, 4, 2, 4 };
785
    int blk, ch;
786
    int frame_bits;
787

    
788
    /* header size */
789
    frame_bits = 65;
790
    frame_bits += frame_bits_inc[s->channel_mode];
791

    
792
    /* audio blocks */
793
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
794
        frame_bits += s->fbw_channels * 2 + 2; /* blksw * c, dithflag * c, dynrnge, cplstre */
795
        if (s->channel_mode == AC3_CHMODE_STEREO) {
796
            frame_bits++; /* rematstr */
797
            if (!blk)
798
                frame_bits += 4;
799
        }
800
        frame_bits += 2 * s->fbw_channels; /* chexpstr[2] * c */
801
        if (s->lfe_on)
802
            frame_bits++; /* lfeexpstr */
803
        for (ch = 0; ch < s->fbw_channels; ch++) {
804
            if (exp_strategy[blk][ch] != EXP_REUSE)
805
                frame_bits += 6 + 2; /* chbwcod[6], gainrng[2] */
806
        }
807
        frame_bits++; /* baie */
808
        frame_bits++; /* snr */
809
        frame_bits += 2; /* delta / skip */
810
    }
811
    frame_bits++; /* cplinu for block 0 */
812
    /* bit alloc info */
813
    /* sdcycod[2], fdcycod[2], sgaincod[2], dbpbcod[2], floorcod[3] */
814
    /* csnroffset[6] */
815
    /* (fsnoffset[4] + fgaincod[4]) * c */
816
    frame_bits += 2*4 + 3 + 6 + s->channels * (4 + 3);
817

    
818
    /* auxdatae, crcrsv */
819
    frame_bits += 2;
820

    
821
    /* CRC */
822
    frame_bits += 16;
823

    
824
    s->frame_bits = frame_bits;
825
}
826

    
827

    
828
/**
829
 * Calculate the number of bits needed to encode a set of mantissas.
830
 */
831
static int compute_mantissa_size(AC3EncodeContext *s, uint8_t *m, int nb_coefs)
832
{
833
    int bits, mant, i;
834

    
835
    bits = 0;
836
    for (i = 0; i < nb_coefs; i++) {
837
        mant = m[i];
838
        switch (mant) {
839
        case 0:
840
            /* nothing */
841
            break;
842
        case 1:
843
            /* 3 mantissa in 5 bits */
844
            if (s->mant1_cnt == 0)
845
                bits += 5;
846
            if (++s->mant1_cnt == 3)
847
                s->mant1_cnt = 0;
848
            break;
849
        case 2:
850
            /* 3 mantissa in 7 bits */
851
            if (s->mant2_cnt == 0)
852
                bits += 7;
853
            if (++s->mant2_cnt == 3)
854
                s->mant2_cnt = 0;
855
            break;
856
        case 3:
857
            bits += 3;
858
            break;
859
        case 4:
860
            /* 2 mantissa in 7 bits */
861
            if (s->mant4_cnt == 0)
862
                bits += 7;
863
            if (++s->mant4_cnt == 2)
864
                s->mant4_cnt = 0;
865
            break;
866
        case 14:
867
            bits += 14;
868
            break;
869
        case 15:
870
            bits += 16;
871
            break;
872
        default:
873
            bits += mant - 1;
874
            break;
875
        }
876
    }
877
    return bits;
878
}
879

    
880

    
881
/**
882
 * Calculate masking curve based on the final exponents.
883
 * Also calculate the power spectral densities to use in future calculations.
884
 */
885
static void bit_alloc_masking(AC3EncodeContext *s,
886
                              uint8_t encoded_exp[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS],
887
                              uint8_t exp_strategy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS],
888
                              int16_t psd[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS],
889
                              int16_t mask[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_CRITICAL_BANDS])
890
{
891
    int blk, ch;
892
    int16_t band_psd[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_CRITICAL_BANDS];
893

    
894
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
895
        for (ch = 0; ch < s->channels; ch++) {
896
            if(exp_strategy[blk][ch] == EXP_REUSE) {
897
                memcpy(psd[blk][ch],  psd[blk-1][ch],  AC3_MAX_COEFS*sizeof(psd[0][0][0]));
898
                memcpy(mask[blk][ch], mask[blk-1][ch], AC3_CRITICAL_BANDS*sizeof(mask[0][0][0]));
899
            } else {
900
                ff_ac3_bit_alloc_calc_psd(encoded_exp[blk][ch], 0,
901
                                          s->nb_coefs[ch],
902
                                          psd[blk][ch], band_psd[blk][ch]);
903
                ff_ac3_bit_alloc_calc_mask(&s->bit_alloc, band_psd[blk][ch],
904
                                           0, s->nb_coefs[ch],
905
                                           ff_ac3_fast_gain_tab[s->fast_gain_code[ch]],
906
                                           ch == s->lfe_channel,
907
                                           DBA_NONE, 0, NULL, NULL, NULL,
908
                                           mask[blk][ch]);
909
            }
910
        }
911
    }
912
}
913

    
914

    
915
/**
916
 * Run the bit allocation with a given SNR offset.
917
 * This calculates the bit allocation pointers that will be used to determine
918
 * the quantization of each mantissa.
919
 * @return the number of bits needed for mantissas if the given SNR offset is
920
 *         is used.
921
 */
922
static int bit_alloc(AC3EncodeContext *s,
923
                     int16_t mask[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_CRITICAL_BANDS],
924
                     int16_t psd[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS],
925
                     uint8_t bap[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS],
926
                     int snr_offset)
927
{
928
    int blk, ch;
929
    int mantissa_bits;
930

    
931
    snr_offset = (snr_offset - 240) << 2;
932

    
933
    mantissa_bits = 0;
934
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
935
        s->mant1_cnt = 0;
936
        s->mant2_cnt = 0;
937
        s->mant4_cnt = 0;
938
        for (ch = 0; ch < s->channels; ch++) {
939
            ff_ac3_bit_alloc_calc_bap(mask[blk][ch], psd[blk][ch], 0,
940
                                      s->nb_coefs[ch], snr_offset,
941
                                      s->bit_alloc.floor, ff_ac3_bap_tab,
942
                                      bap[blk][ch]);
943
            mantissa_bits += compute_mantissa_size(s, bap[blk][ch], s->nb_coefs[ch]);
944
        }
945
    }
946
    return mantissa_bits;
947
}
948

    
949

    
950
/**
951
 * Perform bit allocation search.
952
 * Finds the SNR offset value that maximizes quality and fits in the specified
953
 * frame size.  Output is the SNR offset and a set of bit allocation pointers
954
 * used to quantize the mantissas.
955
 */
956
static int compute_bit_allocation(AC3EncodeContext *s,
957
                                  uint8_t bap[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS],
958
                                  uint8_t encoded_exp[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS],
959
                                  uint8_t exp_strategy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS])
960
{
961
    int ch;
962
    int bits_left;
963
    int snr_offset;
964
    uint8_t bap1[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS];
965
    int16_t psd[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS];
966
    int16_t mask[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_CRITICAL_BANDS];
967

    
968
    /* count frame bits other than exponents and mantissas */
969
    count_frame_bits(s, exp_strategy);
970

    
971
    /* calculate psd and masking curve before doing bit allocation */
972
    bit_alloc_masking(s, encoded_exp, exp_strategy, psd, mask);
973

    
974
    /* now the big work begins : do the bit allocation. Modify the snr
975
       offset until we can pack everything in the requested frame size */
976

    
977
    bits_left = 8 * s->frame_size - (s->frame_bits + s->exponent_bits);
978
    snr_offset = s->coarse_snr_offset << 4;
979
    while (snr_offset >= 0 &&
980
           bit_alloc(s, mask, psd, bap, snr_offset) > bits_left)
981
        snr_offset -= 64;
982
    if (snr_offset < 0) {
983
        return AVERROR(EINVAL);
984
    }
985
    while (snr_offset + 64 <= 1023 &&
986
           bit_alloc(s, mask, psd, bap1,
987
                     snr_offset + 64) <= bits_left) {
988
        snr_offset += 64;
989
        memcpy(bap, bap1, sizeof(bap1));
990
    }
991
    while (snr_offset + 16 <= 1023 &&
992
           bit_alloc(s, mask, psd, bap1, snr_offset + 16) <= bits_left) {
993
        snr_offset += 16;
994
        memcpy(bap, bap1, sizeof(bap1));
995
    }
996
    while (snr_offset + 4 <= 1023 &&
997
           bit_alloc(s, mask, psd, bap1,
998
                     snr_offset + 4) <= bits_left) {
999
        snr_offset += 4;
1000
        memcpy(bap, bap1, sizeof(bap1));
1001
    }
1002
    while (snr_offset + 1 <= 1023 &&
1003
           bit_alloc(s, mask, psd, bap1,
1004
                     snr_offset + 1) <= bits_left) {
1005
        snr_offset++;
1006
        memcpy(bap, bap1, sizeof(bap1));
1007
    }
1008

    
1009
    s->coarse_snr_offset = snr_offset >> 4;
1010
    for (ch = 0; ch < s->channels; ch++)
1011
        s->fine_snr_offset[ch] = snr_offset & 0xF;
1012

    
1013
    return 0;
1014
}
1015

    
1016

    
1017
/**
1018
 * Symmetric quantization on 'levels' levels.
1019
 */
1020
static inline int sym_quant(int c, int e, int levels)
1021
{
1022
    int v;
1023

    
1024
    if (c >= 0) {
1025
        v = (levels * (c << e)) >> 24;
1026
        v = (v + 1) >> 1;
1027
        v = (levels >> 1) + v;
1028
    } else {
1029
        v = (levels * ((-c) << e)) >> 24;
1030
        v = (v + 1) >> 1;
1031
        v = (levels >> 1) - v;
1032
    }
1033
    assert (v >= 0 && v < levels);
1034
    return v;
1035
}
1036

    
1037

    
1038
/**
1039
 * Asymmetric quantization on 2^qbits levels.
1040
 */
1041
static inline int asym_quant(int c, int e, int qbits)
1042
{
1043
    int lshift, m, v;
1044

    
1045
    lshift = e + qbits - 24;
1046
    if (lshift >= 0)
1047
        v = c << lshift;
1048
    else
1049
        v = c >> (-lshift);
1050
    /* rounding */
1051
    v = (v + 1) >> 1;
1052
    m = (1 << (qbits-1));
1053
    if (v >= m)
1054
        v = m - 1;
1055
    assert(v >= -m);
1056
    return v & ((1 << qbits)-1);
1057
}
1058

    
1059

    
1060
/**
1061
 * Quantize a set of mantissas for a single channel in a single block.
1062
 */
1063
static void quantize_mantissas_blk_ch(AC3EncodeContext *s,
1064
                                      int32_t *mdct_coef, int8_t exp_shift,
1065
                                      uint8_t *encoded_exp, uint8_t *bap,
1066
                                      uint16_t *qmant, int n)
1067
{
1068
    int i;
1069

    
1070
    for (i = 0; i < n; i++) {
1071
        int v;
1072
        int c = mdct_coef[i];
1073
        int e = encoded_exp[i] - exp_shift;
1074
        int b = bap[i];
1075
        switch (b) {
1076
        case 0:
1077
            v = 0;
1078
            break;
1079
        case 1:
1080
            v = sym_quant(c, e, 3);
1081
            switch (s->mant1_cnt) {
1082
            case 0:
1083
                s->qmant1_ptr = &qmant[i];
1084
                v = 9 * v;
1085
                s->mant1_cnt = 1;
1086
                break;
1087
            case 1:
1088
                *s->qmant1_ptr += 3 * v;
1089
                s->mant1_cnt = 2;
1090
                v = 128;
1091
                break;
1092
            default:
1093
                *s->qmant1_ptr += v;
1094
                s->mant1_cnt = 0;
1095
                v = 128;
1096
                break;
1097
            }
1098
            break;
1099
        case 2:
1100
            v = sym_quant(c, e, 5);
1101
            switch (s->mant2_cnt) {
1102
            case 0:
1103
                s->qmant2_ptr = &qmant[i];
1104
                v = 25 * v;
1105
                s->mant2_cnt = 1;
1106
                break;
1107
            case 1:
1108
                *s->qmant2_ptr += 5 * v;
1109
                s->mant2_cnt = 2;
1110
                v = 128;
1111
                break;
1112
            default:
1113
                *s->qmant2_ptr += v;
1114
                s->mant2_cnt = 0;
1115
                v = 128;
1116
                break;
1117
            }
1118
            break;
1119
        case 3:
1120
            v = sym_quant(c, e, 7);
1121
            break;
1122
        case 4:
1123
            v = sym_quant(c, e, 11);
1124
            switch (s->mant4_cnt) {
1125
            case 0:
1126
                s->qmant4_ptr = &qmant[i];
1127
                v = 11 * v;
1128
                s->mant4_cnt = 1;
1129
                break;
1130
            default:
1131
                *s->qmant4_ptr += v;
1132
                s->mant4_cnt = 0;
1133
                v = 128;
1134
                break;
1135
            }
1136
            break;
1137
        case 5:
1138
            v = sym_quant(c, e, 15);
1139
            break;
1140
        case 14:
1141
            v = asym_quant(c, e, 14);
1142
            break;
1143
        case 15:
1144
            v = asym_quant(c, e, 16);
1145
            break;
1146
        default:
1147
            v = asym_quant(c, e, b - 1);
1148
            break;
1149
        }
1150
        qmant[i] = v;
1151
    }
1152
}
1153

    
1154

    
1155
/**
1156
 * Quantize mantissas using coefficients, exponents, and bit allocation pointers.
1157
 */
1158
static void quantize_mantissas(AC3EncodeContext *s,
1159
                               int32_t mdct_coef[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS],
1160
                               int8_t exp_shift[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS],
1161
                               uint8_t encoded_exp[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS],
1162
                               uint8_t bap[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS],
1163
                               uint16_t qmant[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS])
1164
{
1165
    int blk, ch;
1166

    
1167

    
1168
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
1169
        s->mant1_cnt  = s->mant2_cnt  = s->mant4_cnt  = 0;
1170
        s->qmant1_ptr = s->qmant2_ptr = s->qmant4_ptr = NULL;
1171

    
1172
        for (ch = 0; ch < s->channels; ch++) {
1173
            quantize_mantissas_blk_ch(s, mdct_coef[blk][ch], exp_shift[blk][ch],
1174
                                      encoded_exp[blk][ch], bap[blk][ch],
1175
                                      qmant[blk][ch], s->nb_coefs[ch]);
1176
        }
1177
    }
1178
}
1179

    
1180

    
1181
/**
1182
 * Write the AC-3 frame header to the output bitstream.
1183
 */
1184
static void output_frame_header(AC3EncodeContext *s)
1185
{
1186
    put_bits(&s->pb, 16, 0x0b77);   /* frame header */
1187
    put_bits(&s->pb, 16, 0);        /* crc1: will be filled later */
1188
    put_bits(&s->pb, 2,  s->bit_alloc.sr_code);
1189
    put_bits(&s->pb, 6,  s->frame_size_code + (s->frame_size - s->frame_size_min) / 2);
1190
    put_bits(&s->pb, 5,  s->bitstream_id);
1191
    put_bits(&s->pb, 3,  s->bitstream_mode);
1192
    put_bits(&s->pb, 3,  s->channel_mode);
1193
    if ((s->channel_mode & 0x01) && s->channel_mode != AC3_CHMODE_MONO)
1194
        put_bits(&s->pb, 2, 1);     /* XXX -4.5 dB */
1195
    if (s->channel_mode & 0x04)
1196
        put_bits(&s->pb, 2, 1);     /* XXX -6 dB */
1197
    if (s->channel_mode == AC3_CHMODE_STEREO)
1198
        put_bits(&s->pb, 2, 0);     /* surround not indicated */
1199
    put_bits(&s->pb, 1, s->lfe_on); /* LFE */
1200
    put_bits(&s->pb, 5, 31);        /* dialog norm: -31 db */
1201
    put_bits(&s->pb, 1, 0);         /* no compression control word */
1202
    put_bits(&s->pb, 1, 0);         /* no lang code */
1203
    put_bits(&s->pb, 1, 0);         /* no audio production info */
1204
    put_bits(&s->pb, 1, 0);         /* no copyright */
1205
    put_bits(&s->pb, 1, 1);         /* original bitstream */
1206
    put_bits(&s->pb, 1, 0);         /* no time code 1 */
1207
    put_bits(&s->pb, 1, 0);         /* no time code 2 */
1208
    put_bits(&s->pb, 1, 0);         /* no additional bit stream info */
1209
}
1210

    
1211

    
1212
/**
1213
 * Write one audio block to the output bitstream.
1214
 */
1215
static void output_audio_block(AC3EncodeContext *s,
1216
                               uint8_t exp_strategy[AC3_MAX_CHANNELS],
1217
                               uint8_t num_exp_groups[AC3_MAX_CHANNELS],
1218
                               uint8_t grouped_exp[AC3_MAX_CHANNELS][AC3_MAX_EXP_GROUPS],
1219
                               uint8_t bap[AC3_MAX_CHANNELS][AC3_MAX_COEFS],
1220
                               uint16_t qmant[AC3_MAX_CHANNELS][AC3_MAX_COEFS],
1221
                               int block_num)
1222
{
1223
    int ch, i, baie, rbnd;
1224

    
1225
    for (ch = 0; ch < s->fbw_channels; ch++)
1226
        put_bits(&s->pb, 1, 0); /* no block switching */
1227
    for (ch = 0; ch < s->fbw_channels; ch++)
1228
        put_bits(&s->pb, 1, 1); /* no dither */
1229
    put_bits(&s->pb, 1, 0);     /* no dynamic range */
1230
    if (!block_num) {
1231
        put_bits(&s->pb, 1, 1); /* coupling strategy present */
1232
        put_bits(&s->pb, 1, 0); /* no coupling strategy */
1233
    } else {
1234
        put_bits(&s->pb, 1, 0); /* no new coupling strategy */
1235
    }
1236

    
1237
    if (s->channel_mode == AC3_CHMODE_STEREO) {
1238
        if (!block_num) {
1239
            /* first block must define rematrixing (rematstr) */
1240
            put_bits(&s->pb, 1, 1);
1241

    
1242
            /* dummy rematrixing rematflg(1:4)=0 */
1243
            for (rbnd = 0; rbnd < 4; rbnd++)
1244
                put_bits(&s->pb, 1, 0);
1245
        } else {
1246
            /* no matrixing (but should be used in the future) */
1247
            put_bits(&s->pb, 1, 0);
1248
        }
1249
    }
1250

    
1251
    /* exponent strategy */
1252
    for (ch = 0; ch < s->fbw_channels; ch++)
1253
        put_bits(&s->pb, 2, exp_strategy[ch]);
1254

    
1255
    if (s->lfe_on)
1256
        put_bits(&s->pb, 1, exp_strategy[s->lfe_channel]);
1257

    
1258
    /* bandwidth */
1259
    for (ch = 0; ch < s->fbw_channels; ch++) {
1260
        if (exp_strategy[ch] != EXP_REUSE)
1261
            put_bits(&s->pb, 6, s->bandwidth_code[ch]);
1262
    }
1263

    
1264
    /* exponents */
1265
    for (ch = 0; ch < s->channels; ch++) {
1266
        if (exp_strategy[ch] == EXP_REUSE)
1267
            continue;
1268

    
1269
        /* first exponent */
1270
        put_bits(&s->pb, 4, grouped_exp[ch][0]);
1271

    
1272
        /* next ones are delta-encoded and grouped */
1273
        for (i = 1; i <= num_exp_groups[ch]; i++)
1274
            put_bits(&s->pb, 7, grouped_exp[ch][i]);
1275

    
1276
        if (ch != s->lfe_channel)
1277
            put_bits(&s->pb, 2, 0); /* no gain range info */
1278
    }
1279

    
1280
    /* bit allocation info */
1281
    baie = (block_num == 0);
1282
    put_bits(&s->pb, 1, baie);
1283
    if (baie) {
1284
        put_bits(&s->pb, 2, s->slow_decay_code);
1285
        put_bits(&s->pb, 2, s->fast_decay_code);
1286
        put_bits(&s->pb, 2, s->slow_gain_code);
1287
        put_bits(&s->pb, 2, s->db_per_bit_code);
1288
        put_bits(&s->pb, 3, s->floor_code);
1289
    }
1290

    
1291
    /* snr offset */
1292
    put_bits(&s->pb, 1, baie);
1293
    if (baie) {
1294
        put_bits(&s->pb, 6, s->coarse_snr_offset);
1295
        for (ch = 0; ch < s->channels; ch++) {
1296
            put_bits(&s->pb, 4, s->fine_snr_offset[ch]);
1297
            put_bits(&s->pb, 3, s->fast_gain_code[ch]);
1298
        }
1299
    }
1300

    
1301
    put_bits(&s->pb, 1, 0); /* no delta bit allocation */
1302
    put_bits(&s->pb, 1, 0); /* no data to skip */
1303

    
1304
    /* mantissa encoding */
1305
    for (ch = 0; ch < s->channels; ch++) {
1306
        int b, q;
1307

    
1308
        for (i = 0; i < s->nb_coefs[ch]; i++) {
1309
            q = qmant[ch][i];
1310
            b = bap[ch][i];
1311
            switch (b) {
1312
            case 0:                                         break;
1313
            case 1: if (q != 128) put_bits(&s->pb,   5, q); break;
1314
            case 2: if (q != 128) put_bits(&s->pb,   7, q); break;
1315
            case 3:               put_bits(&s->pb,   3, q); break;
1316
            case 4: if (q != 128) put_bits(&s->pb,   7, q); break;
1317
            case 14:              put_bits(&s->pb,  14, q); break;
1318
            case 15:              put_bits(&s->pb,  16, q); break;
1319
            default:              put_bits(&s->pb, b-1, q); break;
1320
            }
1321
        }
1322
    }
1323
}
1324

    
1325

    
1326
/** CRC-16 Polynomial */
1327
#define CRC16_POLY ((1 << 0) | (1 << 2) | (1 << 15) | (1 << 16))
1328

    
1329

    
1330
static unsigned int mul_poly(unsigned int a, unsigned int b, unsigned int poly)
1331
{
1332
    unsigned int c;
1333

    
1334
    c = 0;
1335
    while (a) {
1336
        if (a & 1)
1337
            c ^= b;
1338
        a = a >> 1;
1339
        b = b << 1;
1340
        if (b & (1 << 16))
1341
            b ^= poly;
1342
    }
1343
    return c;
1344
}
1345

    
1346

    
1347
static unsigned int pow_poly(unsigned int a, unsigned int n, unsigned int poly)
1348
{
1349
    unsigned int r;
1350
    r = 1;
1351
    while (n) {
1352
        if (n & 1)
1353
            r = mul_poly(r, a, poly);
1354
        a = mul_poly(a, a, poly);
1355
        n >>= 1;
1356
    }
1357
    return r;
1358
}
1359

    
1360

    
1361
/**
1362
 * Fill the end of the frame with 0's and compute the two CRCs.
1363
 */
1364
static void output_frame_end(AC3EncodeContext *s)
1365
{
1366
    int frame_size, frame_size_58, pad_bytes, crc1, crc2, crc_inv;
1367
    uint8_t *frame;
1368

    
1369
    frame_size = s->frame_size; /* frame size in words */
1370
    /* align to 8 bits */
1371
    flush_put_bits(&s->pb);
1372
    /* add zero bytes to reach the frame size */
1373
    frame = s->pb.buf;
1374
    pad_bytes = s->frame_size - (put_bits_ptr(&s->pb) - frame) - 2;
1375
    assert(pad_bytes >= 0);
1376
    if (pad_bytes > 0)
1377
        memset(put_bits_ptr(&s->pb), 0, pad_bytes);
1378

    
1379
    /* Now we must compute both crcs : this is not so easy for crc1
1380
       because it is at the beginning of the data... */
1381
    frame_size_58 = ((frame_size >> 2) + (frame_size >> 4)) << 1;
1382

    
1383
    crc1 = av_bswap16(av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0,
1384
                             frame + 4, frame_size_58 - 4));
1385

    
1386
    /* XXX: could precompute crc_inv */
1387
    crc_inv = pow_poly((CRC16_POLY >> 1), (8 * frame_size_58) - 16, CRC16_POLY);
1388
    crc1    = mul_poly(crc_inv, crc1, CRC16_POLY);
1389
    AV_WB16(frame + 2, crc1);
1390

    
1391
    crc2 = av_bswap16(av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0,
1392
                             frame + frame_size_58,
1393
                             frame_size - frame_size_58 - 2));
1394
    AV_WB16(frame + frame_size - 2, crc2);
1395
}
1396

    
1397

    
1398
/**
1399
 * Write the frame to the output bitstream.
1400
 */
1401
static void output_frame(AC3EncodeContext *s,
1402
                         unsigned char *frame,
1403
                         uint8_t exp_strategy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS],
1404
                         uint8_t num_exp_groups[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS],
1405
                         uint8_t grouped_exp[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_EXP_GROUPS],
1406
                         uint8_t bap[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS],
1407
                         uint16_t qmant[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS])
1408
{
1409
    int blk;
1410

    
1411
    init_put_bits(&s->pb, frame, AC3_MAX_CODED_FRAME_SIZE);
1412

    
1413
    output_frame_header(s);
1414

    
1415
    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
1416
        output_audio_block(s, exp_strategy[blk], num_exp_groups[blk],
1417
                           grouped_exp[blk], bap[blk], qmant[blk], blk);
1418
    }
1419

    
1420
    output_frame_end(s);
1421
}
1422

    
1423

    
1424
/**
1425
 * Encode a single AC-3 frame.
1426
 */
1427
static int ac3_encode_frame(AVCodecContext *avctx,
1428
                            unsigned char *frame, int buf_size, void *data)
1429
{
1430
    AC3EncodeContext *s = avctx->priv_data;
1431
    const int16_t *samples = data;
1432
    int16_t planar_samples[AC3_MAX_CHANNELS][AC3_BLOCK_SIZE+AC3_FRAME_SIZE];
1433
    int32_t mdct_coef[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS];
1434
    uint8_t exp[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS];
1435
    uint8_t exp_strategy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS];
1436
    uint8_t encoded_exp[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS];
1437
    uint8_t num_exp_groups[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS];
1438
    uint8_t grouped_exp[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_EXP_GROUPS];
1439
    uint8_t bap[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS];
1440
    int8_t exp_shift[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS];
1441
    uint16_t qmant[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS];
1442
    int ret;
1443

    
1444
    if (s->bit_alloc.sr_code == 1)
1445
        adjust_frame_size(s);
1446

    
1447
    deinterleave_input_samples(s, samples, planar_samples);
1448

    
1449
    apply_mdct(s, planar_samples, exp_shift, mdct_coef);
1450

    
1451
    process_exponents(s, mdct_coef, exp_shift, exp, exp_strategy, encoded_exp,
1452
                      num_exp_groups, grouped_exp);
1453

    
1454
    ret = compute_bit_allocation(s, bap, encoded_exp, exp_strategy);
1455
    if (ret) {
1456
        av_log(avctx, AV_LOG_ERROR, "Bit allocation failed. Try increasing the bitrate.\n");
1457
        return ret;
1458
    }
1459

    
1460
    quantize_mantissas(s, mdct_coef, exp_shift, encoded_exp, bap, qmant);
1461

    
1462
    output_frame(s, frame, exp_strategy, num_exp_groups, grouped_exp, bap, qmant);
1463

    
1464
    return s->frame_size;
1465
}
1466

    
1467

    
1468
/**
1469
 * Finalize encoding and free any memory allocated by the encoder.
1470
 */
1471
static av_cold int ac3_encode_close(AVCodecContext *avctx)
1472
{
1473
    av_freep(&avctx->coded_frame);
1474
    return 0;
1475
}
1476

    
1477

    
1478
/**
1479
 * Set channel information during initialization.
1480
 */
1481
static av_cold int set_channel_info(AC3EncodeContext *s, int channels,
1482
                                    int64_t *channel_layout)
1483
{
1484
    int ch_layout;
1485

    
1486
    if (channels < 1 || channels > AC3_MAX_CHANNELS)
1487
        return AVERROR(EINVAL);
1488
    if ((uint64_t)*channel_layout > 0x7FF)
1489
        return AVERROR(EINVAL);
1490
    ch_layout = *channel_layout;
1491
    if (!ch_layout)
1492
        ch_layout = avcodec_guess_channel_layout(channels, CODEC_ID_AC3, NULL);
1493
    if (av_get_channel_layout_nb_channels(ch_layout) != channels)
1494
        return AVERROR(EINVAL);
1495

    
1496
    s->lfe_on       = !!(ch_layout & AV_CH_LOW_FREQUENCY);
1497
    s->channels     = channels;
1498
    s->fbw_channels = channels - s->lfe_on;
1499
    s->lfe_channel  = s->lfe_on ? s->fbw_channels : -1;
1500
    if (s->lfe_on)
1501
        ch_layout -= AV_CH_LOW_FREQUENCY;
1502

    
1503
    switch (ch_layout) {
1504
    case AV_CH_LAYOUT_MONO:           s->channel_mode = AC3_CHMODE_MONO;   break;
1505
    case AV_CH_LAYOUT_STEREO:         s->channel_mode = AC3_CHMODE_STEREO; break;
1506
    case AV_CH_LAYOUT_SURROUND:       s->channel_mode = AC3_CHMODE_3F;     break;
1507
    case AV_CH_LAYOUT_2_1:            s->channel_mode = AC3_CHMODE_2F1R;   break;
1508
    case AV_CH_LAYOUT_4POINT0:        s->channel_mode = AC3_CHMODE_3F1R;   break;
1509
    case AV_CH_LAYOUT_QUAD:
1510
    case AV_CH_LAYOUT_2_2:            s->channel_mode = AC3_CHMODE_2F2R;   break;
1511
    case AV_CH_LAYOUT_5POINT0:
1512
    case AV_CH_LAYOUT_5POINT0_BACK:   s->channel_mode = AC3_CHMODE_3F2R;   break;
1513
    default:
1514
        return AVERROR(EINVAL);
1515
    }
1516

    
1517
    s->channel_map  = ff_ac3_enc_channel_map[s->channel_mode][s->lfe_on];
1518
    *channel_layout = ch_layout;
1519
    if (s->lfe_on)
1520
        *channel_layout |= AV_CH_LOW_FREQUENCY;
1521

    
1522
    return 0;
1523
}
1524

    
1525

    
1526
static av_cold int validate_options(AVCodecContext *avctx, AC3EncodeContext *s)
1527
{
1528
    int i, ret;
1529

    
1530
    /* validate channel layout */
1531
    if (!avctx->channel_layout) {
1532
        av_log(avctx, AV_LOG_WARNING, "No channel layout specified. The "
1533
                                      "encoder will guess the layout, but it "
1534
                                      "might be incorrect.\n");
1535
    }
1536
    ret = set_channel_info(s, avctx->channels, &avctx->channel_layout);
1537
    if (ret) {
1538
        av_log(avctx, AV_LOG_ERROR, "invalid channel layout\n");
1539
        return ret;
1540
    }
1541

    
1542
    /* validate sample rate */
1543
    for (i = 0; i < 9; i++) {
1544
        if ((ff_ac3_sample_rate_tab[i / 3] >> (i % 3)) == avctx->sample_rate)
1545
            break;
1546
    }
1547
    if (i == 9) {
1548
        av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n");
1549
        return AVERROR(EINVAL);
1550
    }
1551
    s->sample_rate        = avctx->sample_rate;
1552
    s->bit_alloc.sr_shift = i % 3;
1553
    s->bit_alloc.sr_code  = i / 3;
1554

    
1555
    /* validate bit rate */
1556
    for (i = 0; i < 19; i++) {
1557
        if ((ff_ac3_bitrate_tab[i] >> s->bit_alloc.sr_shift)*1000 == avctx->bit_rate)
1558
            break;
1559
    }
1560
    if (i == 19) {
1561
        av_log(avctx, AV_LOG_ERROR, "invalid bit rate\n");
1562
        return AVERROR(EINVAL);
1563
    }
1564
    s->bit_rate        = avctx->bit_rate;
1565
    s->frame_size_code = i << 1;
1566

    
1567
    return 0;
1568
}
1569

    
1570

    
1571
/**
1572
 * Set bandwidth for all channels.
1573
 * The user can optionally supply a cutoff frequency. Otherwise an appropriate
1574
 * default value will be used.
1575
 */
1576
static av_cold void set_bandwidth(AC3EncodeContext *s, int cutoff)
1577
{
1578
    int ch, bw_code;
1579

    
1580
    if (cutoff) {
1581
        /* calculate bandwidth based on user-specified cutoff frequency */
1582
        int fbw_coeffs;
1583
        cutoff         = av_clip(cutoff, 1, s->sample_rate >> 1);
1584
        fbw_coeffs     = cutoff * 2 * AC3_MAX_COEFS / s->sample_rate;
1585
        bw_code        = av_clip((fbw_coeffs - 73) / 3, 0, 60);
1586
    } else {
1587
        /* use default bandwidth setting */
1588
        /* XXX: should compute the bandwidth according to the frame
1589
           size, so that we avoid annoying high frequency artifacts */
1590
        bw_code = 50;
1591
    }
1592

    
1593
    /* set number of coefficients for each channel */
1594
    for (ch = 0; ch < s->fbw_channels; ch++) {
1595
        s->bandwidth_code[ch] = bw_code;
1596
        s->nb_coefs[ch]       = bw_code * 3 + 73;
1597
    }
1598
    if (s->lfe_on)
1599
        s->nb_coefs[s->lfe_channel] = 7; /* LFE channel always has 7 coefs */
1600
}
1601

    
1602

    
1603
/**
1604
 * Initialize the encoder.
1605
 */
1606
static av_cold int ac3_encode_init(AVCodecContext *avctx)
1607
{
1608
    AC3EncodeContext *s = avctx->priv_data;
1609
    int ret;
1610

    
1611
    avctx->frame_size = AC3_FRAME_SIZE;
1612

    
1613
    ac3_common_init();
1614

    
1615
    ret = validate_options(avctx, s);
1616
    if (ret)
1617
        return ret;
1618

    
1619
    s->bitstream_id   = 8 + s->bit_alloc.sr_shift;
1620
    s->bitstream_mode = 0; /* complete main audio service */
1621

    
1622
    s->frame_size_min  = 2 * ff_ac3_frame_size_tab[s->frame_size_code][s->bit_alloc.sr_code];
1623
    s->bits_written    = 0;
1624
    s->samples_written = 0;
1625
    s->frame_size      = s->frame_size_min;
1626

    
1627
    set_bandwidth(s, avctx->cutoff);
1628

    
1629
    bit_alloc_init(s);
1630

    
1631
    mdct_init(9);
1632

    
1633
    avctx->coded_frame= avcodec_alloc_frame();
1634
    avctx->coded_frame->key_frame= 1;
1635

    
1636
    return 0;
1637
}
1638

    
1639

    
1640
#ifdef TEST
1641
/*************************************************************************/
1642
/* TEST */
1643

    
1644
#include "libavutil/lfg.h"
1645

    
1646
#define FN (MDCT_SAMPLES/4)
1647

    
1648

    
1649
static void fft_test(AVLFG *lfg)
1650
{
1651
    IComplex in[FN], in1[FN];
1652
    int k, n, i;
1653
    float sum_re, sum_im, a;
1654

    
1655
    for (i = 0; i < FN; i++) {
1656
        in[i].re = av_lfg_get(lfg) % 65535 - 32767;
1657
        in[i].im = av_lfg_get(lfg) % 65535 - 32767;
1658
        in1[i]   = in[i];
1659
    }
1660
    fft(in, 7);
1661

    
1662
    /* do it by hand */
1663
    for (k = 0; k < FN; k++) {
1664
        sum_re = 0;
1665
        sum_im = 0;
1666
        for (n = 0; n < FN; n++) {
1667
            a = -2 * M_PI * (n * k) / FN;
1668
            sum_re += in1[n].re * cos(a) - in1[n].im * sin(a);
1669
            sum_im += in1[n].re * sin(a) + in1[n].im * cos(a);
1670
        }
1671
        av_log(NULL, AV_LOG_DEBUG, "%3d: %6d,%6d %6.0f,%6.0f\n",
1672
               k, in[k].re, in[k].im, sum_re / FN, sum_im / FN);
1673
    }
1674
}
1675

    
1676

    
1677
static void mdct_test(AVLFG *lfg)
1678
{
1679
    int16_t input[MDCT_SAMPLES];
1680
    int32_t output[AC3_MAX_COEFS];
1681
    float input1[MDCT_SAMPLES];
1682
    float output1[AC3_MAX_COEFS];
1683
    float s, a, err, e, emax;
1684
    int i, k, n;
1685

    
1686
    for (i = 0; i < MDCT_SAMPLES; i++) {
1687
        input[i]  = (av_lfg_get(lfg) % 65535 - 32767) * 9 / 10;
1688
        input1[i] = input[i];
1689
    }
1690

    
1691
    mdct512(output, input);
1692

    
1693
    /* do it by hand */
1694
    for (k = 0; k < AC3_MAX_COEFS; k++) {
1695
        s = 0;
1696
        for (n = 0; n < MDCT_SAMPLES; n++) {
1697
            a = (2*M_PI*(2*n+1+MDCT_SAMPLES/2)*(2*k+1) / (4 * MDCT_SAMPLES));
1698
            s += input1[n] * cos(a);
1699
        }
1700
        output1[k] = -2 * s / MDCT_SAMPLES;
1701
    }
1702

    
1703
    err  = 0;
1704
    emax = 0;
1705
    for (i = 0; i < AC3_MAX_COEFS; i++) {
1706
        av_log(NULL, AV_LOG_DEBUG, "%3d: %7d %7.0f\n", i, output[i], output1[i]);
1707
        e = output[i] - output1[i];
1708
        if (e > emax)
1709
            emax = e;
1710
        err += e * e;
1711
    }
1712
    av_log(NULL, AV_LOG_DEBUG, "err2=%f emax=%f\n", err / AC3_MAX_COEFS, emax);
1713
}
1714

    
1715

    
1716
int main(void)
1717
{
1718
    AVLFG lfg;
1719

    
1720
    av_log_set_level(AV_LOG_DEBUG);
1721
    mdct_init(9);
1722

    
1723
    fft_test(&lfg);
1724
    mdct_test(&lfg);
1725

    
1726
    return 0;
1727
}
1728
#endif /* TEST */
1729

    
1730

    
1731
AVCodec ac3_encoder = {
1732
    "ac3",
1733
    AVMEDIA_TYPE_AUDIO,
1734
    CODEC_ID_AC3,
1735
    sizeof(AC3EncodeContext),
1736
    ac3_encode_init,
1737
    ac3_encode_frame,
1738
    ac3_encode_close,
1739
    NULL,
1740
    .sample_fmts = (const enum AVSampleFormat[]){AV_SAMPLE_FMT_S16,AV_SAMPLE_FMT_NONE},
1741
    .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),
1742
    .channel_layouts = (const int64_t[]){
1743
        AV_CH_LAYOUT_MONO,
1744
        AV_CH_LAYOUT_STEREO,
1745
        AV_CH_LAYOUT_2_1,
1746
        AV_CH_LAYOUT_SURROUND,
1747
        AV_CH_LAYOUT_2_2,
1748
        AV_CH_LAYOUT_QUAD,
1749
        AV_CH_LAYOUT_4POINT0,
1750
        AV_CH_LAYOUT_5POINT0,
1751
        AV_CH_LAYOUT_5POINT0_BACK,
1752
       (AV_CH_LAYOUT_MONO     | AV_CH_LOW_FREQUENCY),
1753
       (AV_CH_LAYOUT_STEREO   | AV_CH_LOW_FREQUENCY),
1754
       (AV_CH_LAYOUT_2_1      | AV_CH_LOW_FREQUENCY),
1755
       (AV_CH_LAYOUT_SURROUND | AV_CH_LOW_FREQUENCY),
1756
       (AV_CH_LAYOUT_2_2      | AV_CH_LOW_FREQUENCY),
1757
       (AV_CH_LAYOUT_QUAD     | AV_CH_LOW_FREQUENCY),
1758
       (AV_CH_LAYOUT_4POINT0  | AV_CH_LOW_FREQUENCY),
1759
        AV_CH_LAYOUT_5POINT1,
1760
        AV_CH_LAYOUT_5POINT1_BACK,
1761
        0 },
1762
};