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1
/*
2
 * The simplest mpeg audio layer 2 encoder
3
 * Copyright (c) 2000, 2001 Fabrice Bellard.
4
 *
5
 * 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
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 * version 2 of the License, or (at your option) any later version.
9
 *
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 * This library is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
13
 * Lesser General Public License for more details.
14
 *
15
 * You should have received a copy of the GNU Lesser General Public
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 * License along with this library; if not, write to the Free Software
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 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
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 */
19
#include "avcodec.h"
20
#include "mpegaudio.h"
21

    
22
/* currently, cannot change these constants (need to modify
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   quantization stage) */
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#define FRAC_BITS 15
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#define WFRAC_BITS  14
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#define MUL(a,b) (((INT64)(a) * (INT64)(b)) >> FRAC_BITS)
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#define FIX(a)   ((int)((a) * (1 << FRAC_BITS)))
28

    
29
#define SAMPLES_BUF_SIZE 4096
30

    
31
typedef struct MpegAudioContext {
32
    PutBitContext pb;
33
    int nb_channels;
34
    int freq, bit_rate;
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    int lsf;           /* 1 if mpeg2 low bitrate selected */
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    int bitrate_index; /* bit rate */
37
    int freq_index;
38
    int frame_size; /* frame size, in bits, without padding */
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    INT64 nb_samples; /* total number of samples encoded */
40
    /* padding computation */
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    int frame_frac, frame_frac_incr, do_padding;
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    short samples_buf[MPA_MAX_CHANNELS][SAMPLES_BUF_SIZE]; /* buffer for filter */
43
    int samples_offset[MPA_MAX_CHANNELS];       /* offset in samples_buf */
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    int sb_samples[MPA_MAX_CHANNELS][3][12][SBLIMIT];
45
    unsigned char scale_factors[MPA_MAX_CHANNELS][SBLIMIT][3]; /* scale factors */
46
    /* code to group 3 scale factors */
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    unsigned char scale_code[MPA_MAX_CHANNELS][SBLIMIT];       
48
    int sblimit; /* number of used subbands */
49
    const unsigned char *alloc_table;
50
} MpegAudioContext;
51

    
52
/* define it to use floats in quantization (I don't like floats !) */
53
//#define USE_FLOATS
54

    
55
#include "mpegaudiotab.h"
56

    
57
int MPA_encode_init(AVCodecContext *avctx)
58
{
59
    MpegAudioContext *s = avctx->priv_data;
60
    int freq = avctx->sample_rate;
61
    int bitrate = avctx->bit_rate;
62
    int channels = avctx->channels;
63
    int i, v, table;
64
    float a;
65

    
66
    if (channels > 2)
67
        return -1;
68
    bitrate = bitrate / 1000;
69
    s->nb_channels = channels;
70
    s->freq = freq;
71
    s->bit_rate = bitrate * 1000;
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    avctx->frame_size = MPA_FRAME_SIZE;
73

    
74
    /* encoding freq */
75
    s->lsf = 0;
76
    for(i=0;i<3;i++) {
77
        if (mpa_freq_tab[i] == freq) 
78
            break;
79
        if ((mpa_freq_tab[i] / 2) == freq) {
80
            s->lsf = 1;
81
            break;
82
        }
83
    }
84
    if (i == 3)
85
        return -1;
86
    s->freq_index = i;
87

    
88
    /* encoding bitrate & frequency */
89
    for(i=0;i<15;i++) {
90
        if (mpa_bitrate_tab[s->lsf][1][i] == bitrate) 
91
            break;
92
    }
93
    if (i == 15)
94
        return -1;
95
    s->bitrate_index = i;
96

    
97
    /* compute total header size & pad bit */
98
    
99
    a = (float)(bitrate * 1000 * MPA_FRAME_SIZE) / (freq * 8.0);
100
    s->frame_size = ((int)a) * 8;
101

    
102
    /* frame fractional size to compute padding */
103
    s->frame_frac = 0;
104
    s->frame_frac_incr = (int)((a - floor(a)) * 65536.0);
105
    
106
    /* select the right allocation table */
107
    table = l2_select_table(bitrate, s->nb_channels, freq, s->lsf);
108

    
109
    /* number of used subbands */
110
    s->sblimit = sblimit_table[table];
111
    s->alloc_table = alloc_tables[table];
112

    
113
#ifdef DEBUG
114
    printf("%d kb/s, %d Hz, frame_size=%d bits, table=%d, padincr=%x\n", 
115
           bitrate, freq, s->frame_size, table, s->frame_frac_incr);
116
#endif
117

    
118
    for(i=0;i<s->nb_channels;i++)
119
        s->samples_offset[i] = 0;
120

    
121
    for(i=0;i<257;i++) {
122
        int v;
123
        v = mpa_enwindow[i];
124
#if WFRAC_BITS != 16
125
        v = (v + (1 << (16 - WFRAC_BITS - 1))) >> (16 - WFRAC_BITS);
126
#endif
127
        filter_bank[i] = v;
128
        if ((i & 63) != 0)
129
            v = -v;
130
        if (i != 0)
131
            filter_bank[512 - i] = v;
132
    }
133

    
134
    for(i=0;i<64;i++) {
135
        v = (int)(pow(2.0, (3 - i) / 3.0) * (1 << 20));
136
        if (v <= 0)
137
            v = 1;
138
        scale_factor_table[i] = v;
139
#ifdef USE_FLOATS
140
        scale_factor_inv_table[i] = pow(2.0, -(3 - i) / 3.0) / (float)(1 << 20);
141
#else
142
#define P 15
143
        scale_factor_shift[i] = 21 - P - (i / 3);
144
        scale_factor_mult[i] = (1 << P) * pow(2.0, (i % 3) / 3.0);
145
#endif
146
    }
147
    for(i=0;i<128;i++) {
148
        v = i - 64;
149
        if (v <= -3)
150
            v = 0;
151
        else if (v < 0)
152
            v = 1;
153
        else if (v == 0)
154
            v = 2;
155
        else if (v < 3)
156
            v = 3;
157
        else 
158
            v = 4;
159
        scale_diff_table[i] = v;
160
    }
161

    
162
    for(i=0;i<17;i++) {
163
        v = quant_bits[i];
164
        if (v < 0) 
165
            v = -v;
166
        else
167
            v = v * 3;
168
        total_quant_bits[i] = 12 * v;
169
    }
170

    
171
    avctx->coded_frame= avcodec_alloc_frame();
172
    avctx->coded_frame->key_frame= 1;
173

    
174
    return 0;
175
}
176

    
177
/* 32 point floating point IDCT without 1/sqrt(2) coef zero scaling */
178
static void idct32(int *out, int *tab)
179
{
180
    int i, j;
181
    int *t, *t1, xr;
182
    const int *xp = costab32;
183

    
184
    for(j=31;j>=3;j-=2) tab[j] += tab[j - 2];
185
    
186
    t = tab + 30;
187
    t1 = tab + 2;
188
    do {
189
        t[0] += t[-4];
190
        t[1] += t[1 - 4];
191
        t -= 4;
192
    } while (t != t1);
193

    
194
    t = tab + 28;
195
    t1 = tab + 4;
196
    do {
197
        t[0] += t[-8];
198
        t[1] += t[1-8];
199
        t[2] += t[2-8];
200
        t[3] += t[3-8];
201
        t -= 8;
202
    } while (t != t1);
203
    
204
    t = tab;
205
    t1 = tab + 32;
206
    do {
207
        t[ 3] = -t[ 3];    
208
        t[ 6] = -t[ 6];    
209
        
210
        t[11] = -t[11];    
211
        t[12] = -t[12];    
212
        t[13] = -t[13];    
213
        t[15] = -t[15]; 
214
        t += 16;
215
    } while (t != t1);
216

    
217
    
218
    t = tab;
219
    t1 = tab + 8;
220
    do {
221
        int x1, x2, x3, x4;
222
        
223
        x3 = MUL(t[16], FIX(SQRT2*0.5));
224
        x4 = t[0] - x3;
225
        x3 = t[0] + x3;
226
        
227
        x2 = MUL(-(t[24] + t[8]), FIX(SQRT2*0.5));
228
        x1 = MUL((t[8] - x2), xp[0]);
229
        x2 = MUL((t[8] + x2), xp[1]);
230

    
231
        t[ 0] = x3 + x1;
232
        t[ 8] = x4 - x2;
233
        t[16] = x4 + x2;
234
        t[24] = x3 - x1;
235
        t++;
236
    } while (t != t1);
237

    
238
    xp += 2;
239
    t = tab;
240
    t1 = tab + 4;
241
    do {
242
        xr = MUL(t[28],xp[0]);
243
        t[28] = (t[0] - xr);
244
        t[0] = (t[0] + xr);
245

    
246
        xr = MUL(t[4],xp[1]);
247
        t[ 4] = (t[24] - xr);
248
        t[24] = (t[24] + xr);
249
        
250
        xr = MUL(t[20],xp[2]);
251
        t[20] = (t[8] - xr);
252
        t[ 8] = (t[8] + xr);
253
            
254
        xr = MUL(t[12],xp[3]);
255
        t[12] = (t[16] - xr);
256
        t[16] = (t[16] + xr);
257
        t++;
258
    } while (t != t1);
259
    xp += 4;
260

    
261
    for (i = 0; i < 4; i++) {
262
        xr = MUL(tab[30-i*4],xp[0]);
263
        tab[30-i*4] = (tab[i*4] - xr);
264
        tab[   i*4] = (tab[i*4] + xr);
265
        
266
        xr = MUL(tab[ 2+i*4],xp[1]);
267
        tab[ 2+i*4] = (tab[28-i*4] - xr);
268
        tab[28-i*4] = (tab[28-i*4] + xr);
269
        
270
        xr = MUL(tab[31-i*4],xp[0]);
271
        tab[31-i*4] = (tab[1+i*4] - xr);
272
        tab[ 1+i*4] = (tab[1+i*4] + xr);
273
        
274
        xr = MUL(tab[ 3+i*4],xp[1]);
275
        tab[ 3+i*4] = (tab[29-i*4] - xr);
276
        tab[29-i*4] = (tab[29-i*4] + xr);
277
        
278
        xp += 2;
279
    }
280

    
281
    t = tab + 30;
282
    t1 = tab + 1;
283
    do {
284
        xr = MUL(t1[0], *xp);
285
        t1[0] = (t[0] - xr);
286
        t[0] = (t[0] + xr);
287
        t -= 2;
288
        t1 += 2;
289
        xp++;
290
    } while (t >= tab);
291

    
292
    for(i=0;i<32;i++) {
293
        out[i] = tab[bitinv32[i]];
294
    }
295
}
296

    
297
#define WSHIFT (WFRAC_BITS + 15 - FRAC_BITS)
298

    
299
static void filter(MpegAudioContext *s, int ch, short *samples, int incr)
300
{
301
    short *p, *q;
302
    int sum, offset, i, j;
303
    int tmp[64];
304
    int tmp1[32];
305
    int *out;
306

    
307
    //    print_pow1(samples, 1152);
308

    
309
    offset = s->samples_offset[ch];
310
    out = &s->sb_samples[ch][0][0][0];
311
    for(j=0;j<36;j++) {
312
        /* 32 samples at once */
313
        for(i=0;i<32;i++) {
314
            s->samples_buf[ch][offset + (31 - i)] = samples[0];
315
            samples += incr;
316
        }
317

    
318
        /* filter */
319
        p = s->samples_buf[ch] + offset;
320
        q = filter_bank;
321
        /* maxsum = 23169 */
322
        for(i=0;i<64;i++) {
323
            sum = p[0*64] * q[0*64];
324
            sum += p[1*64] * q[1*64];
325
            sum += p[2*64] * q[2*64];
326
            sum += p[3*64] * q[3*64];
327
            sum += p[4*64] * q[4*64];
328
            sum += p[5*64] * q[5*64];
329
            sum += p[6*64] * q[6*64];
330
            sum += p[7*64] * q[7*64];
331
            tmp[i] = sum;
332
            p++;
333
            q++;
334
        }
335
        tmp1[0] = tmp[16] >> WSHIFT;
336
        for( i=1; i<=16; i++ ) tmp1[i] = (tmp[i+16]+tmp[16-i]) >> WSHIFT;
337
        for( i=17; i<=31; i++ ) tmp1[i] = (tmp[i+16]-tmp[80-i]) >> WSHIFT;
338

    
339
        idct32(out, tmp1);
340

    
341
        /* advance of 32 samples */
342
        offset -= 32;
343
        out += 32;
344
        /* handle the wrap around */
345
        if (offset < 0) {
346
            memmove(s->samples_buf[ch] + SAMPLES_BUF_SIZE - (512 - 32), 
347
                    s->samples_buf[ch], (512 - 32) * 2);
348
            offset = SAMPLES_BUF_SIZE - 512;
349
        }
350
    }
351
    s->samples_offset[ch] = offset;
352

    
353
    //    print_pow(s->sb_samples, 1152);
354
}
355

    
356
static void compute_scale_factors(unsigned char scale_code[SBLIMIT],
357
                                  unsigned char scale_factors[SBLIMIT][3], 
358
                                  int sb_samples[3][12][SBLIMIT],
359
                                  int sblimit)
360
{
361
    int *p, vmax, v, n, i, j, k, code;
362
    int index, d1, d2;
363
    unsigned char *sf = &scale_factors[0][0];
364
    
365
    for(j=0;j<sblimit;j++) {
366
        for(i=0;i<3;i++) {
367
            /* find the max absolute value */
368
            p = &sb_samples[i][0][j];
369
            vmax = abs(*p);
370
            for(k=1;k<12;k++) {
371
                p += SBLIMIT;
372
                v = abs(*p);
373
                if (v > vmax)
374
                    vmax = v;
375
            }
376
            /* compute the scale factor index using log 2 computations */
377
            if (vmax > 0) {
378
                n = av_log2(vmax);
379
                /* n is the position of the MSB of vmax. now 
380
                   use at most 2 compares to find the index */
381
                index = (21 - n) * 3 - 3;
382
                if (index >= 0) {
383
                    while (vmax <= scale_factor_table[index+1])
384
                        index++;
385
                } else {
386
                    index = 0; /* very unlikely case of overflow */
387
                }
388
            } else {
389
                index = 62; /* value 63 is not allowed */
390
            }
391

    
392
#if 0
393
            printf("%2d:%d in=%x %x %d\n", 
394
                   j, i, vmax, scale_factor_table[index], index);
395
#endif
396
            /* store the scale factor */
397
            assert(index >=0 && index <= 63);
398
            sf[i] = index;
399
        }
400

    
401
        /* compute the transmission factor : look if the scale factors
402
           are close enough to each other */
403
        d1 = scale_diff_table[sf[0] - sf[1] + 64];
404
        d2 = scale_diff_table[sf[1] - sf[2] + 64];
405
        
406
        /* handle the 25 cases */
407
        switch(d1 * 5 + d2) {
408
        case 0*5+0:
409
        case 0*5+4:
410
        case 3*5+4:
411
        case 4*5+0:
412
        case 4*5+4:
413
            code = 0;
414
            break;
415
        case 0*5+1:
416
        case 0*5+2:
417
        case 4*5+1:
418
        case 4*5+2:
419
            code = 3;
420
            sf[2] = sf[1];
421
            break;
422
        case 0*5+3:
423
        case 4*5+3:
424
            code = 3;
425
            sf[1] = sf[2];
426
            break;
427
        case 1*5+0:
428
        case 1*5+4:
429
        case 2*5+4:
430
            code = 1;
431
            sf[1] = sf[0];
432
            break;
433
        case 1*5+1:
434
        case 1*5+2:
435
        case 2*5+0:
436
        case 2*5+1:
437
        case 2*5+2:
438
            code = 2;
439
            sf[1] = sf[2] = sf[0];
440
            break;
441
        case 2*5+3:
442
        case 3*5+3:
443
            code = 2;
444
            sf[0] = sf[1] = sf[2];
445
            break;
446
        case 3*5+0:
447
        case 3*5+1:
448
        case 3*5+2:
449
            code = 2;
450
            sf[0] = sf[2] = sf[1];
451
            break;
452
        case 1*5+3:
453
            code = 2;
454
            if (sf[0] > sf[2])
455
              sf[0] = sf[2];
456
            sf[1] = sf[2] = sf[0];
457
            break;
458
        default:
459
            av_abort();
460
        }
461
        
462
#if 0
463
        printf("%d: %2d %2d %2d %d %d -> %d\n", j, 
464
               sf[0], sf[1], sf[2], d1, d2, code);
465
#endif
466
        scale_code[j] = code;
467
        sf += 3;
468
    }
469
}
470

    
471
/* The most important function : psycho acoustic module. In this
472
   encoder there is basically none, so this is the worst you can do,
473
   but also this is the simpler. */
474
static void psycho_acoustic_model(MpegAudioContext *s, short smr[SBLIMIT])
475
{
476
    int i;
477

    
478
    for(i=0;i<s->sblimit;i++) {
479
        smr[i] = (int)(fixed_smr[i] * 10);
480
    }
481
}
482

    
483

    
484
#define SB_NOTALLOCATED  0
485
#define SB_ALLOCATED     1
486
#define SB_NOMORE        2
487

    
488
/* Try to maximize the smr while using a number of bits inferior to
489
   the frame size. I tried to make the code simpler, faster and
490
   smaller than other encoders :-) */
491
static void compute_bit_allocation(MpegAudioContext *s, 
492
                                   short smr1[MPA_MAX_CHANNELS][SBLIMIT],
493
                                   unsigned char bit_alloc[MPA_MAX_CHANNELS][SBLIMIT],
494
                                   int *padding)
495
{
496
    int i, ch, b, max_smr, max_ch, max_sb, current_frame_size, max_frame_size;
497
    int incr;
498
    short smr[MPA_MAX_CHANNELS][SBLIMIT];
499
    unsigned char subband_status[MPA_MAX_CHANNELS][SBLIMIT];
500
    const unsigned char *alloc;
501

    
502
    memcpy(smr, smr1, s->nb_channels * sizeof(short) * SBLIMIT);
503
    memset(subband_status, SB_NOTALLOCATED, s->nb_channels * SBLIMIT);
504
    memset(bit_alloc, 0, s->nb_channels * SBLIMIT);
505
    
506
    /* compute frame size and padding */
507
    max_frame_size = s->frame_size;
508
    s->frame_frac += s->frame_frac_incr;
509
    if (s->frame_frac >= 65536) {
510
        s->frame_frac -= 65536;
511
        s->do_padding = 1;
512
        max_frame_size += 8;
513
    } else {
514
        s->do_padding = 0;
515
    }
516

    
517
    /* compute the header + bit alloc size */
518
    current_frame_size = 32;
519
    alloc = s->alloc_table;
520
    for(i=0;i<s->sblimit;i++) {
521
        incr = alloc[0];
522
        current_frame_size += incr * s->nb_channels;
523
        alloc += 1 << incr;
524
    }
525
    for(;;) {
526
        /* look for the subband with the largest signal to mask ratio */
527
        max_sb = -1;
528
        max_ch = -1;
529
        max_smr = 0x80000000;
530
        for(ch=0;ch<s->nb_channels;ch++) {
531
            for(i=0;i<s->sblimit;i++) {
532
                if (smr[ch][i] > max_smr && subband_status[ch][i] != SB_NOMORE) {
533
                    max_smr = smr[ch][i];
534
                    max_sb = i;
535
                    max_ch = ch;
536
                }
537
            }
538
        }
539
#if 0
540
        printf("current=%d max=%d max_sb=%d alloc=%d\n", 
541
               current_frame_size, max_frame_size, max_sb,
542
               bit_alloc[max_sb]);
543
#endif        
544
        if (max_sb < 0)
545
            break;
546
        
547
        /* find alloc table entry (XXX: not optimal, should use
548
           pointer table) */
549
        alloc = s->alloc_table;
550
        for(i=0;i<max_sb;i++) {
551
            alloc += 1 << alloc[0];
552
        }
553

    
554
        if (subband_status[max_ch][max_sb] == SB_NOTALLOCATED) {
555
            /* nothing was coded for this band: add the necessary bits */
556
            incr = 2 + nb_scale_factors[s->scale_code[max_ch][max_sb]] * 6;
557
            incr += total_quant_bits[alloc[1]];
558
        } else {
559
            /* increments bit allocation */
560
            b = bit_alloc[max_ch][max_sb];
561
            incr = total_quant_bits[alloc[b + 1]] - 
562
                total_quant_bits[alloc[b]];
563
        }
564

    
565
        if (current_frame_size + incr <= max_frame_size) {
566
            /* can increase size */
567
            b = ++bit_alloc[max_ch][max_sb];
568
            current_frame_size += incr;
569
            /* decrease smr by the resolution we added */
570
            smr[max_ch][max_sb] = smr1[max_ch][max_sb] - quant_snr[alloc[b]];
571
            /* max allocation size reached ? */
572
            if (b == ((1 << alloc[0]) - 1))
573
                subband_status[max_ch][max_sb] = SB_NOMORE;
574
            else
575
                subband_status[max_ch][max_sb] = SB_ALLOCATED;
576
        } else {
577
            /* cannot increase the size of this subband */
578
            subband_status[max_ch][max_sb] = SB_NOMORE;
579
        }
580
    }
581
    *padding = max_frame_size - current_frame_size;
582
    assert(*padding >= 0);
583

    
584
#if 0
585
    for(i=0;i<s->sblimit;i++) {
586
        printf("%d ", bit_alloc[i]);
587
    }
588
    printf("\n");
589
#endif
590
}
591

    
592
/*
593
 * Output the mpeg audio layer 2 frame. Note how the code is small
594
 * compared to other encoders :-)
595
 */
596
static void encode_frame(MpegAudioContext *s,
597
                         unsigned char bit_alloc[MPA_MAX_CHANNELS][SBLIMIT],
598
                         int padding)
599
{
600
    int i, j, k, l, bit_alloc_bits, b, ch;
601
    unsigned char *sf;
602
    int q[3];
603
    PutBitContext *p = &s->pb;
604

    
605
    /* header */
606

    
607
    put_bits(p, 12, 0xfff);
608
    put_bits(p, 1, 1 - s->lsf); /* 1 = mpeg1 ID, 0 = mpeg2 lsf ID */
609
    put_bits(p, 2, 4-2);  /* layer 2 */
610
    put_bits(p, 1, 1); /* no error protection */
611
    put_bits(p, 4, s->bitrate_index);
612
    put_bits(p, 2, s->freq_index);
613
    put_bits(p, 1, s->do_padding); /* use padding */
614
    put_bits(p, 1, 0);             /* private_bit */
615
    put_bits(p, 2, s->nb_channels == 2 ? MPA_STEREO : MPA_MONO);
616
    put_bits(p, 2, 0); /* mode_ext */
617
    put_bits(p, 1, 0); /* no copyright */
618
    put_bits(p, 1, 1); /* original */
619
    put_bits(p, 2, 0); /* no emphasis */
620

    
621
    /* bit allocation */
622
    j = 0;
623
    for(i=0;i<s->sblimit;i++) {
624
        bit_alloc_bits = s->alloc_table[j];
625
        for(ch=0;ch<s->nb_channels;ch++) {
626
            put_bits(p, bit_alloc_bits, bit_alloc[ch][i]);
627
        }
628
        j += 1 << bit_alloc_bits;
629
    }
630
    
631
    /* scale codes */
632
    for(i=0;i<s->sblimit;i++) {
633
        for(ch=0;ch<s->nb_channels;ch++) {
634
            if (bit_alloc[ch][i]) 
635
                put_bits(p, 2, s->scale_code[ch][i]);
636
        }
637
    }
638

    
639
    /* scale factors */
640
    for(i=0;i<s->sblimit;i++) {
641
        for(ch=0;ch<s->nb_channels;ch++) {
642
            if (bit_alloc[ch][i]) {
643
                sf = &s->scale_factors[ch][i][0];
644
                switch(s->scale_code[ch][i]) {
645
                case 0:
646
                    put_bits(p, 6, sf[0]);
647
                    put_bits(p, 6, sf[1]);
648
                    put_bits(p, 6, sf[2]);
649
                    break;
650
                case 3:
651
                case 1:
652
                    put_bits(p, 6, sf[0]);
653
                    put_bits(p, 6, sf[2]);
654
                    break;
655
                case 2:
656
                    put_bits(p, 6, sf[0]);
657
                    break;
658
                }
659
            }
660
        }
661
    }
662
    
663
    /* quantization & write sub band samples */
664

    
665
    for(k=0;k<3;k++) {
666
        for(l=0;l<12;l+=3) {
667
            j = 0;
668
            for(i=0;i<s->sblimit;i++) {
669
                bit_alloc_bits = s->alloc_table[j];
670
                for(ch=0;ch<s->nb_channels;ch++) {
671
                    b = bit_alloc[ch][i];
672
                    if (b) {
673
                        int qindex, steps, m, sample, bits;
674
                        /* we encode 3 sub band samples of the same sub band at a time */
675
                        qindex = s->alloc_table[j+b];
676
                        steps = quant_steps[qindex];
677
                        for(m=0;m<3;m++) {
678
                            sample = s->sb_samples[ch][k][l + m][i];
679
                            /* divide by scale factor */
680
#ifdef USE_FLOATS
681
                            {
682
                                float a;
683
                                a = (float)sample * scale_factor_inv_table[s->scale_factors[ch][i][k]];
684
                                q[m] = (int)((a + 1.0) * steps * 0.5);
685
                            }
686
#else
687
                            {
688
                                int q1, e, shift, mult;
689
                                e = s->scale_factors[ch][i][k];
690
                                shift = scale_factor_shift[e];
691
                                mult = scale_factor_mult[e];
692
                                
693
                                /* normalize to P bits */
694
                                if (shift < 0)
695
                                    q1 = sample << (-shift);
696
                                else
697
                                    q1 = sample >> shift;
698
                                q1 = (q1 * mult) >> P;
699
                                q[m] = ((q1 + (1 << P)) * steps) >> (P + 1);
700
                            }
701
#endif
702
                            if (q[m] >= steps)
703
                                q[m] = steps - 1;
704
                            assert(q[m] >= 0 && q[m] < steps);
705
                        }
706
                        bits = quant_bits[qindex];
707
                        if (bits < 0) {
708
                            /* group the 3 values to save bits */
709
                            put_bits(p, -bits, 
710
                                     q[0] + steps * (q[1] + steps * q[2]));
711
#if 0
712
                            printf("%d: gr1 %d\n", 
713
                                   i, q[0] + steps * (q[1] + steps * q[2]));
714
#endif
715
                        } else {
716
#if 0
717
                            printf("%d: gr3 %d %d %d\n", 
718
                                   i, q[0], q[1], q[2]);
719
#endif                               
720
                            put_bits(p, bits, q[0]);
721
                            put_bits(p, bits, q[1]);
722
                            put_bits(p, bits, q[2]);
723
                        }
724
                    }
725
                }
726
                /* next subband in alloc table */
727
                j += 1 << bit_alloc_bits; 
728
            }
729
        }
730
    }
731

    
732
    /* padding */
733
    for(i=0;i<padding;i++)
734
        put_bits(p, 1, 0);
735

    
736
    /* flush */
737
    flush_put_bits(p);
738
}
739

    
740
int MPA_encode_frame(AVCodecContext *avctx,
741
                     unsigned char *frame, int buf_size, void *data)
742
{
743
    MpegAudioContext *s = avctx->priv_data;
744
    short *samples = data;
745
    short smr[MPA_MAX_CHANNELS][SBLIMIT];
746
    unsigned char bit_alloc[MPA_MAX_CHANNELS][SBLIMIT];
747
    int padding, i;
748

    
749
    for(i=0;i<s->nb_channels;i++) {
750
        filter(s, i, samples + i, s->nb_channels);
751
    }
752

    
753
    for(i=0;i<s->nb_channels;i++) {
754
        compute_scale_factors(s->scale_code[i], s->scale_factors[i], 
755
                              s->sb_samples[i], s->sblimit);
756
    }
757
    for(i=0;i<s->nb_channels;i++) {
758
        psycho_acoustic_model(s, smr[i]);
759
    }
760
    compute_bit_allocation(s, smr, bit_alloc, &padding);
761

    
762
    init_put_bits(&s->pb, frame, MPA_MAX_CODED_FRAME_SIZE, NULL, NULL);
763

    
764
    encode_frame(s, bit_alloc, padding);
765
    
766
    s->nb_samples += MPA_FRAME_SIZE;
767
    return pbBufPtr(&s->pb) - s->pb.buf;
768
}
769

    
770
static int MPA_encode_close(AVCodecContext *avctx)
771
{
772
    av_freep(&avctx->coded_frame);
773
    return 0;
774
}
775

    
776
AVCodec mp2_encoder = {
777
    "mp2",
778
    CODEC_TYPE_AUDIO,
779
    CODEC_ID_MP2,
780
    sizeof(MpegAudioContext),
781
    MPA_encode_init,
782
    MPA_encode_frame,
783
    MPA_encode_close,
784
    NULL,
785
};
786

    
787
#undef FIX