summaryrefslogtreecommitdiffstats
path: root/libavcodec/imc.c
blob: cfed7c471252076fb9a0a10d61398258a3400e9d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
/*
 * IMC compatible decoder
 * Copyright (c) 2002-2004 Maxim Poliakovski
 * Copyright (c) 2006 Benjamin Larsson
 * Copyright (c) 2006 Konstantin Shishkov
 *
 * This file is part of Libav.
 *
 * Libav is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * Libav is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with Libav; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

/**
 *  @file
 *  IMC - Intel Music Coder
 *  A mdct based codec using a 256 points large transform
 *  divied into 32 bands with some mix of scale factors.
 *  Only mono is supported.
 *
 */


#include <math.h>
#include <stddef.h>
#include <stdio.h>

#include "avcodec.h"
#include "get_bits.h"
#include "dsputil.h"
#include "fft.h"
#include "libavutil/audioconvert.h"
#include "sinewin.h"

#include "imcdata.h"

#define IMC_BLOCK_SIZE 64
#define IMC_FRAME_ID 0x21
#define BANDS 32
#define COEFFS 256

typedef struct {
    AVFrame frame;

    float old_floor[BANDS];
    float flcoeffs1[BANDS];
    float flcoeffs2[BANDS];
    float flcoeffs3[BANDS];
    float flcoeffs4[BANDS];
    float flcoeffs5[BANDS];
    float flcoeffs6[BANDS];
    float CWdecoded[COEFFS];

    /** MDCT tables */
    //@{
    float mdct_sine_window[COEFFS];
    float post_cos[COEFFS];
    float post_sin[COEFFS];
    float pre_coef1[COEFFS];
    float pre_coef2[COEFFS];
    float last_fft_im[COEFFS];
    //@}

    int bandWidthT[BANDS];     ///< codewords per band
    int bitsBandT[BANDS];      ///< how many bits per codeword in band
    int CWlengthT[COEFFS];     ///< how many bits in each codeword
    int levlCoeffBuf[BANDS];
    int bandFlagsBuf[BANDS];   ///< flags for each band
    int sumLenArr[BANDS];      ///< bits for all coeffs in band
    int skipFlagRaw[BANDS];    ///< skip flags are stored in raw form or not
    int skipFlagBits[BANDS];   ///< bits used to code skip flags
    int skipFlagCount[BANDS];  ///< skipped coeffients per band
    int skipFlags[COEFFS];     ///< skip coefficient decoding or not
    int codewords[COEFFS];     ///< raw codewords read from bitstream
    float sqrt_tab[30];
    GetBitContext gb;
    int decoder_reset;
    float one_div_log2;

    DSPContext dsp;
    FFTContext fft;
    DECLARE_ALIGNED(32, FFTComplex, samples)[COEFFS/2];
    float *out_samples;
} IMCContext;

static VLC huffman_vlc[4][4];

#define VLC_TABLES_SIZE 9512

static const int vlc_offsets[17] = {
    0,     640, 1156, 1732, 2308, 2852, 3396, 3924,
    4452, 5220, 5860, 6628, 7268, 7908, 8424, 8936, VLC_TABLES_SIZE};

static VLC_TYPE vlc_tables[VLC_TABLES_SIZE][2];

static av_cold int imc_decode_init(AVCodecContext * avctx)
{
    int i, j, ret;
    IMCContext *q = avctx->priv_data;
    double r1, r2;

    if (avctx->channels != 1) {
        av_log_ask_for_sample(avctx, "Number of channels is not supported\n");
        return AVERROR_PATCHWELCOME;
    }

    q->decoder_reset = 1;

    for(i = 0; i < BANDS; i++)
        q->old_floor[i] = 1.0;

    /* Build mdct window, a simple sine window normalized with sqrt(2) */
    ff_sine_window_init(q->mdct_sine_window, COEFFS);
    for(i = 0; i < COEFFS; i++)
        q->mdct_sine_window[i] *= sqrt(2.0);
    for(i = 0; i < COEFFS/2; i++){
        q->post_cos[i] = (1.0f / 32768) * cos(i / 256.0 * M_PI);
        q->post_sin[i] = (1.0f / 32768) * sin(i / 256.0 * M_PI);

        r1 = sin((i * 4.0 + 1.0) / 1024.0 * M_PI);
        r2 = cos((i * 4.0 + 1.0) / 1024.0 * M_PI);

        if (i & 0x1)
        {
            q->pre_coef1[i] =  (r1 + r2) * sqrt(2.0);
            q->pre_coef2[i] = -(r1 - r2) * sqrt(2.0);
        }
        else
        {
            q->pre_coef1[i] = -(r1 + r2) * sqrt(2.0);
            q->pre_coef2[i] =  (r1 - r2) * sqrt(2.0);
        }

        q->last_fft_im[i] = 0;
    }

    /* Generate a square root table */

    for(i = 0; i < 30; i++) {
        q->sqrt_tab[i] = sqrt(i);
    }

    /* initialize the VLC tables */
    for(i = 0; i < 4 ; i++) {
        for(j = 0; j < 4; j++) {
            huffman_vlc[i][j].table = &vlc_tables[vlc_offsets[i * 4 + j]];
            huffman_vlc[i][j].table_allocated = vlc_offsets[i * 4 + j + 1] - vlc_offsets[i * 4 + j];
            init_vlc(&huffman_vlc[i][j], 9, imc_huffman_sizes[i],
                     imc_huffman_lens[i][j], 1, 1,
                     imc_huffman_bits[i][j], 2, 2, INIT_VLC_USE_NEW_STATIC);
        }
    }
    q->one_div_log2 = 1/log(2);

    if ((ret = ff_fft_init(&q->fft, 7, 1))) {
        av_log(avctx, AV_LOG_INFO, "FFT init failed\n");
        return ret;
    }
    ff_dsputil_init(&q->dsp, avctx);
    avctx->sample_fmt = AV_SAMPLE_FMT_FLT;
    avctx->channel_layout = AV_CH_LAYOUT_MONO;

    avcodec_get_frame_defaults(&q->frame);
    avctx->coded_frame = &q->frame;

    return 0;
}

static void imc_calculate_coeffs(IMCContext* q, float* flcoeffs1, float* flcoeffs2, int* bandWidthT,
                                float* flcoeffs3, float* flcoeffs5)
{
    float   workT1[BANDS];
    float   workT2[BANDS];
    float   workT3[BANDS];
    float   snr_limit = 1.e-30;
    float   accum = 0.0;
    int i, cnt2;

    for(i = 0; i < BANDS; i++) {
        flcoeffs5[i] = workT2[i] = 0.0;
        if (bandWidthT[i]){
            workT1[i] = flcoeffs1[i] * flcoeffs1[i];
            flcoeffs3[i] = 2.0 * flcoeffs2[i];
        } else {
            workT1[i] = 0.0;
            flcoeffs3[i] = -30000.0;
        }
        workT3[i] = bandWidthT[i] * workT1[i] * 0.01;
        if (workT3[i] <= snr_limit)
            workT3[i] = 0.0;
    }

    for(i = 0; i < BANDS; i++) {
        for(cnt2 = i; cnt2 < cyclTab[i]; cnt2++)
            flcoeffs5[cnt2] = flcoeffs5[cnt2] + workT3[i];
        workT2[cnt2-1] = workT2[cnt2-1] + workT3[i];
    }

    for(i = 1; i < BANDS; i++) {
        accum = (workT2[i-1] + accum) * imc_weights1[i-1];
        flcoeffs5[i] += accum;
    }

    for(i = 0; i < BANDS; i++)
        workT2[i] = 0.0;

    for(i = 0; i < BANDS; i++) {
        for(cnt2 = i-1; cnt2 > cyclTab2[i]; cnt2--)
            flcoeffs5[cnt2] += workT3[i];
        workT2[cnt2+1] += workT3[i];
    }

    accum = 0.0;

    for(i = BANDS-2; i >= 0; i--) {
        accum = (workT2[i+1] + accum) * imc_weights2[i];
        flcoeffs5[i] += accum;
        //there is missing code here, but it seems to never be triggered
    }
}


static void imc_read_level_coeffs(IMCContext* q, int stream_format_code, int* levlCoeffs)
{
    int i;
    VLC *hufftab[4];
    int start = 0;
    const uint8_t *cb_sel;
    int s;

    s = stream_format_code >> 1;
    hufftab[0] = &huffman_vlc[s][0];
    hufftab[1] = &huffman_vlc[s][1];
    hufftab[2] = &huffman_vlc[s][2];
    hufftab[3] = &huffman_vlc[s][3];
    cb_sel = imc_cb_select[s];

    if(stream_format_code & 4)
        start = 1;
    if(start)
        levlCoeffs[0] = get_bits(&q->gb, 7);
    for(i = start; i < BANDS; i++){
        levlCoeffs[i] = get_vlc2(&q->gb, hufftab[cb_sel[i]]->table, hufftab[cb_sel[i]]->bits, 2);
        if(levlCoeffs[i] == 17)
            levlCoeffs[i] += get_bits(&q->gb, 4);
    }
}

static void imc_decode_level_coefficients(IMCContext* q, int* levlCoeffBuf, float* flcoeffs1,
                                         float* flcoeffs2)
{
    int i, level;
    float tmp, tmp2;
    //maybe some frequency division thingy

    flcoeffs1[0] = 20000.0 / pow (2, levlCoeffBuf[0] * 0.18945); // 0.18945 = log2(10) * 0.05703125
    flcoeffs2[0] = log(flcoeffs1[0])/log(2);
    tmp = flcoeffs1[0];
    tmp2 = flcoeffs2[0];

    for(i = 1; i < BANDS; i++) {
        level = levlCoeffBuf[i];
        if (level == 16) {
            flcoeffs1[i] = 1.0;
            flcoeffs2[i] = 0.0;
        } else {
            if (level < 17)
                level -=7;
            else if (level <= 24)
                level -=32;
            else
                level -=16;

            tmp  *= imc_exp_tab[15 + level];
            tmp2 += 0.83048 * level;  // 0.83048 = log2(10) * 0.25
            flcoeffs1[i] = tmp;
            flcoeffs2[i] = tmp2;
        }
    }
}


static void imc_decode_level_coefficients2(IMCContext* q, int* levlCoeffBuf, float* old_floor, float* flcoeffs1,
                                          float* flcoeffs2) {
    int i;
        //FIXME maybe flag_buf = noise coding and flcoeffs1 = new scale factors
        //      and flcoeffs2 old scale factors
        //      might be incomplete due to a missing table that is in the binary code
    for(i = 0; i < BANDS; i++) {
        flcoeffs1[i] = 0;
        if(levlCoeffBuf[i] < 16) {
            flcoeffs1[i] = imc_exp_tab2[levlCoeffBuf[i]] * old_floor[i];
            flcoeffs2[i] = (levlCoeffBuf[i]-7) * 0.83048 + flcoeffs2[i]; // 0.83048 = log2(10) * 0.25
        } else {
            flcoeffs1[i] = old_floor[i];
        }
    }
}

/**
 * Perform bit allocation depending on bits available
 */
static int bit_allocation (IMCContext* q, int stream_format_code, int freebits, int flag) {
    int i, j;
    const float limit = -1.e20;
    float highest = 0.0;
    int indx;
    int t1 = 0;
    int t2 = 1;
    float summa = 0.0;
    int iacc = 0;
    int summer = 0;
    int rres, cwlen;
    float lowest = 1.e10;
    int low_indx = 0;
    float workT[32];
    int flg;
    int found_indx = 0;

    for(i = 0; i < BANDS; i++)
        highest = FFMAX(highest, q->flcoeffs1[i]);

    for(i = 0; i < BANDS-1; i++) {
        q->flcoeffs4[i] = q->flcoeffs3[i] - log(q->flcoeffs5[i])/log(2);
    }
    q->flcoeffs4[BANDS - 1] = limit;

    highest = highest * 0.25;

    for(i = 0; i < BANDS; i++) {
        indx = -1;
        if ((band_tab[i+1] - band_tab[i]) == q->bandWidthT[i])
            indx = 0;

        if ((band_tab[i+1] - band_tab[i]) > q->bandWidthT[i])
            indx = 1;

        if (((band_tab[i+1] - band_tab[i])/2) >= q->bandWidthT[i])
            indx = 2;

        if (indx == -1)
            return AVERROR_INVALIDDATA;

        q->flcoeffs4[i] = q->flcoeffs4[i] + xTab[(indx*2 + (q->flcoeffs1[i] < highest)) * 2 + flag];
    }

    if (stream_format_code & 0x2) {
        q->flcoeffs4[0] = limit;
        q->flcoeffs4[1] = limit;
        q->flcoeffs4[2] = limit;
        q->flcoeffs4[3] = limit;
    }

    for(i = (stream_format_code & 0x2)?4:0; i < BANDS-1; i++) {
        iacc += q->bandWidthT[i];
        summa += q->bandWidthT[i] * q->flcoeffs4[i];
    }
    q->bandWidthT[BANDS-1] = 0;
    summa = (summa * 0.5 - freebits) / iacc;


    for(i = 0; i < BANDS/2; i++) {
        rres = summer - freebits;
        if((rres >= -8) && (rres <= 8)) break;

        summer = 0;
        iacc = 0;

        for(j = (stream_format_code & 0x2)?4:0; j < BANDS; j++) {
            cwlen = av_clipf(((q->flcoeffs4[j] * 0.5) - summa + 0.5), 0, 6);

            q->bitsBandT[j] = cwlen;
            summer += q->bandWidthT[j] * cwlen;

            if (cwlen > 0)
                iacc += q->bandWidthT[j];
        }

        flg = t2;
        t2 = 1;
        if (freebits < summer)
            t2 = -1;
        if (i == 0)
            flg = t2;
        if(flg != t2)
            t1++;

        summa = (float)(summer - freebits) / ((t1 + 1) * iacc) + summa;
    }

    for(i = (stream_format_code & 0x2)?4:0; i < BANDS; i++) {
        for(j = band_tab[i]; j < band_tab[i+1]; j++)
            q->CWlengthT[j] = q->bitsBandT[i];
    }

    if (freebits > summer) {
        for(i = 0; i < BANDS; i++) {
            workT[i] = (q->bitsBandT[i] == 6) ? -1.e20 : (q->bitsBandT[i] * -2 + q->flcoeffs4[i] - 0.415);
        }

        highest = 0.0;

        do{
            if (highest <= -1.e20)
                break;

            found_indx = 0;
            highest = -1.e20;

            for(i = 0; i < BANDS; i++) {
                if (workT[i] > highest) {
                    highest = workT[i];
                    found_indx = i;
                }
            }

            if (highest > -1.e20) {
                workT[found_indx] -= 2.0;
                if (++(q->bitsBandT[found_indx]) == 6)
                    workT[found_indx] = -1.e20;

                for(j = band_tab[found_indx]; j < band_tab[found_indx+1] && (freebits > summer); j++){
                    q->CWlengthT[j]++;
                    summer++;
                }
            }
        }while (freebits > summer);
    }
    if (freebits < summer) {
        for(i = 0; i < BANDS; i++) {
            workT[i] = q->bitsBandT[i] ? (q->bitsBandT[i] * -2 + q->flcoeffs4[i] + 1.585) : 1.e20;
        }
        if (stream_format_code & 0x2) {
            workT[0] = 1.e20;
            workT[1] = 1.e20;
            workT[2] = 1.e20;
            workT[3] = 1.e20;
        }
        while (freebits < summer){
            lowest = 1.e10;
            low_indx = 0;
            for(i = 0; i < BANDS; i++) {
                if (workT[i] < lowest) {
                    lowest = workT[i];
                    low_indx = i;
                }
            }
            //if(lowest >= 1.e10) break;
            workT[low_indx] = lowest + 2.0;

            if (!(--q->bitsBandT[low_indx]))
                workT[low_indx] = 1.e20;

            for(j = band_tab[low_indx]; j < band_tab[low_indx+1] && (freebits < summer); j++){
                if(q->CWlengthT[j] > 0){
                    q->CWlengthT[j]--;
                    summer--;
                }
            }
        }
    }
    return 0;
}

static void imc_get_skip_coeff(IMCContext* q) {
    int i, j;

    memset(q->skipFlagBits, 0, sizeof(q->skipFlagBits));
    memset(q->skipFlagCount, 0, sizeof(q->skipFlagCount));
    for(i = 0; i < BANDS; i++) {
        if (!q->bandFlagsBuf[i] || !q->bandWidthT[i])
            continue;

        if (!q->skipFlagRaw[i]) {
            q->skipFlagBits[i] = band_tab[i+1] - band_tab[i];

            for(j = band_tab[i]; j < band_tab[i+1]; j++) {
                if ((q->skipFlags[j] = get_bits1(&q->gb)))
                    q->skipFlagCount[i]++;
            }
        } else {
            for(j = band_tab[i]; j < (band_tab[i+1]-1); j += 2) {
                if(!get_bits1(&q->gb)){//0
                    q->skipFlagBits[i]++;
                    q->skipFlags[j]=1;
                    q->skipFlags[j+1]=1;
                    q->skipFlagCount[i] += 2;
                }else{
                    if(get_bits1(&q->gb)){//11
                        q->skipFlagBits[i] +=2;
                        q->skipFlags[j]=0;
                        q->skipFlags[j+1]=1;
                        q->skipFlagCount[i]++;
                    }else{
                        q->skipFlagBits[i] +=3;
                        q->skipFlags[j+1]=0;
                        if(!get_bits1(&q->gb)){//100
                            q->skipFlags[j]=1;
                            q->skipFlagCount[i]++;
                        }else{//101
                            q->skipFlags[j]=0;
                        }
                    }
                }
            }

            if (j < band_tab[i+1]) {
                q->skipFlagBits[i]++;
                if ((q->skipFlags[j] = get_bits1(&q->gb)))
                    q->skipFlagCount[i]++;
            }
        }
    }
}

/**
 * Increase highest' band coefficient sizes as some bits won't be used
 */
static void imc_adjust_bit_allocation (IMCContext* q, int summer) {
    float workT[32];
    int corrected = 0;
    int i, j;
    float highest = 0;
    int found_indx=0;

    for(i = 0; i < BANDS; i++) {
        workT[i] = (q->bitsBandT[i] == 6) ? -1.e20 : (q->bitsBandT[i] * -2 + q->flcoeffs4[i] - 0.415);
    }

    while (corrected < summer) {
        if(highest <= -1.e20)
            break;

        highest = -1.e20;

        for(i = 0; i < BANDS; i++) {
            if (workT[i] > highest) {
                highest = workT[i];
                found_indx = i;
            }
        }

        if (highest > -1.e20) {
            workT[found_indx] -= 2.0;
            if (++(q->bitsBandT[found_indx]) == 6)
                workT[found_indx] = -1.e20;

            for(j = band_tab[found_indx]; j < band_tab[found_indx+1] && (corrected < summer); j++) {
                if (!q->skipFlags[j] && (q->CWlengthT[j] < 6)) {
                    q->CWlengthT[j]++;
                    corrected++;
                }
            }
        }
    }
}

static void imc_imdct256(IMCContext *q) {
    int i;
    float re, im;

    /* prerotation */
    for(i=0; i < COEFFS/2; i++){
        q->samples[i].re = -(q->pre_coef1[i] * q->CWdecoded[COEFFS-1-i*2]) -
                           (q->pre_coef2[i] * q->CWdecoded[i*2]);
        q->samples[i].im = (q->pre_coef2[i] * q->CWdecoded[COEFFS-1-i*2]) -
                           (q->pre_coef1[i] * q->CWdecoded[i*2]);
    }

    /* FFT */
    q->fft.fft_permute(&q->fft, q->samples);
    q->fft.fft_calc   (&q->fft, q->samples);

    /* postrotation, window and reorder */
    for(i = 0; i < COEFFS/2; i++){
        re = (q->samples[i].re * q->post_cos[i]) + (-q->samples[i].im * q->post_sin[i]);
        im = (-q->samples[i].im * q->post_cos[i]) - (q->samples[i].re * q->post_sin[i]);
        q->out_samples[i*2] = (q->mdct_sine_window[COEFFS-1-i*2] * q->last_fft_im[i]) + (q->mdct_sine_window[i*2] * re);
        q->out_samples[COEFFS-1-i*2] = (q->mdct_sine_window[i*2] * q->last_fft_im[i]) - (q->mdct_sine_window[COEFFS-1-i*2] * re);
        q->last_fft_im[i] = im;
    }
}

static int inverse_quant_coeff (IMCContext* q, int stream_format_code) {
    int i, j;
    int middle_value, cw_len, max_size;
    const float* quantizer;

    for(i = 0; i < BANDS; i++) {
        for(j = band_tab[i]; j < band_tab[i+1]; j++) {
            q->CWdecoded[j] = 0;
            cw_len = q->CWlengthT[j];

            if (cw_len <= 0 || q->skipFlags[j])
                continue;

            max_size = 1 << cw_len;
            middle_value = max_size >> 1;

            if (q->codewords[j] >= max_size || q->codewords[j] < 0)
                return AVERROR_INVALIDDATA;

            if (cw_len >= 4){
                quantizer = imc_quantizer2[(stream_format_code & 2) >> 1];
                if (q->codewords[j] >= middle_value)
                    q->CWdecoded[j] = quantizer[q->codewords[j] - 8] * q->flcoeffs6[i];
                else
                    q->CWdecoded[j] = -quantizer[max_size - q->codewords[j] - 8 - 1] * q->flcoeffs6[i];
            }else{
                quantizer = imc_quantizer1[((stream_format_code & 2) >> 1) | (q->bandFlagsBuf[i] << 1)];
                if (q->codewords[j] >= middle_value)
                    q->CWdecoded[j] = quantizer[q->codewords[j] - 1] * q->flcoeffs6[i];
                else
                    q->CWdecoded[j] = -quantizer[max_size - 2 - q->codewords[j]] * q->flcoeffs6[i];
            }
        }
    }
    return 0;
}


static int imc_get_coeffs (IMCContext* q) {
    int i, j, cw_len, cw;

    for(i = 0; i < BANDS; i++) {
        if(!q->sumLenArr[i]) continue;
        if (q->bandFlagsBuf[i] || q->bandWidthT[i]) {
            for(j = band_tab[i]; j < band_tab[i+1]; j++) {
                cw_len = q->CWlengthT[j];
                cw = 0;

                if (get_bits_count(&q->gb) + cw_len > 512){
//av_log(NULL,0,"Band %i coeff %i cw_len %i\n",i,j,cw_len);
                    return AVERROR_INVALIDDATA;
                }

                if(cw_len && (!q->bandFlagsBuf[i] || !q->skipFlags[j]))
                    cw = get_bits(&q->gb, cw_len);

                q->codewords[j] = cw;
            }
        }
    }
    return 0;
}

static int imc_decode_frame(AVCodecContext * avctx, void *data,
                            int *got_frame_ptr, AVPacket *avpkt)
{
    const uint8_t *buf = avpkt->data;
    int buf_size = avpkt->size;

    IMCContext *q = avctx->priv_data;

    int stream_format_code;
    int imc_hdr, i, j, ret;
    int flag;
    int bits, summer;
    int counter, bitscount;
    LOCAL_ALIGNED_16(uint16_t, buf16, [IMC_BLOCK_SIZE / 2]);

    if (buf_size < IMC_BLOCK_SIZE) {
        av_log(avctx, AV_LOG_ERROR, "imc frame too small!\n");
        return AVERROR_INVALIDDATA;
    }

    /* get output buffer */
    q->frame.nb_samples = COEFFS;
    if ((ret = avctx->get_buffer(avctx, &q->frame)) < 0) {
        av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
        return ret;
    }
    q->out_samples = (float *)q->frame.data[0];

    q->dsp.bswap16_buf(buf16, (const uint16_t*)buf, IMC_BLOCK_SIZE / 2);

    init_get_bits(&q->gb, (const uint8_t*)buf16, IMC_BLOCK_SIZE * 8);

    /* Check the frame header */
    imc_hdr = get_bits(&q->gb, 9);
    if (imc_hdr != IMC_FRAME_ID) {
        av_log(avctx, AV_LOG_ERROR, "imc frame header check failed!\n");
        av_log(avctx, AV_LOG_ERROR, "got %x instead of 0x21.\n", imc_hdr);
        return AVERROR_INVALIDDATA;
    }
    stream_format_code = get_bits(&q->gb, 3);

    if(stream_format_code & 1){
        av_log(avctx, AV_LOG_ERROR, "Stream code format %X is not supported\n", stream_format_code);
        return AVERROR_INVALIDDATA;
    }

//    av_log(avctx, AV_LOG_DEBUG, "stream_format_code = %d\n", stream_format_code);

    if (stream_format_code & 0x04)
        q->decoder_reset = 1;

    if(q->decoder_reset) {
        memset(q->out_samples, 0, sizeof(q->out_samples));
        for(i = 0; i < BANDS; i++)q->old_floor[i] = 1.0;
        for(i = 0; i < COEFFS; i++)q->CWdecoded[i] = 0;
        q->decoder_reset = 0;
    }

    flag = get_bits1(&q->gb);
    imc_read_level_coeffs(q, stream_format_code, q->levlCoeffBuf);

    if (stream_format_code & 0x4)
        imc_decode_level_coefficients(q, q->levlCoeffBuf, q->flcoeffs1, q->flcoeffs2);
    else
        imc_decode_level_coefficients2(q, q->levlCoeffBuf, q->old_floor, q->flcoeffs1, q->flcoeffs2);

    memcpy(q->old_floor, q->flcoeffs1, 32 * sizeof(float));

    counter = 0;
    for (i=0 ; i<BANDS ; i++) {
        if (q->levlCoeffBuf[i] == 16) {
            q->bandWidthT[i] = 0;
            counter++;
        } else
            q->bandWidthT[i] = band_tab[i+1] - band_tab[i];
    }
    memset(q->bandFlagsBuf, 0, BANDS * sizeof(int));
    for(i = 0; i < BANDS-1; i++) {
        if (q->bandWidthT[i])
            q->bandFlagsBuf[i] = get_bits1(&q->gb);
    }

    imc_calculate_coeffs(q, q->flcoeffs1, q->flcoeffs2, q->bandWidthT, q->flcoeffs3, q->flcoeffs5);

    bitscount = 0;
    /* first 4 bands will be assigned 5 bits per coefficient */
    if (stream_format_code & 0x2) {
        bitscount += 15;

        q->bitsBandT[0] = 5;
        q->CWlengthT[0] = 5;
        q->CWlengthT[1] = 5;
        q->CWlengthT[2] = 5;
        for(i = 1; i < 4; i++){
            bits = (q->levlCoeffBuf[i] == 16) ? 0 : 5;
            q->bitsBandT[i] = bits;
            for(j = band_tab[i]; j < band_tab[i+1]; j++) {
                q->CWlengthT[j] = bits;
                bitscount += bits;
            }
        }
    }

    if((ret = bit_allocation (q, stream_format_code,
                              512 - bitscount - get_bits_count(&q->gb), flag)) < 0) {
        av_log(avctx, AV_LOG_ERROR, "Bit allocations failed\n");
        q->decoder_reset = 1;
        return ret;
    }

    for(i = 0; i < BANDS; i++) {
        q->sumLenArr[i] = 0;
        q->skipFlagRaw[i] = 0;
        for(j = band_tab[i]; j < band_tab[i+1]; j++)
            q->sumLenArr[i] += q->CWlengthT[j];
        if (q->bandFlagsBuf[i])
            if( (((band_tab[i+1] - band_tab[i]) * 1.5) > q->sumLenArr[i]) && (q->sumLenArr[i] > 0))
                q->skipFlagRaw[i] = 1;
    }

    imc_get_skip_coeff(q);

    for(i = 0; i < BANDS; i++) {
        q->flcoeffs6[i] = q->flcoeffs1[i];
        /* band has flag set and at least one coded coefficient */
        if (q->bandFlagsBuf[i] && (band_tab[i+1] - band_tab[i]) != q->skipFlagCount[i]){
                q->flcoeffs6[i] *= q->sqrt_tab[band_tab[i+1] - band_tab[i]] /
                                   q->sqrt_tab[(band_tab[i+1] - band_tab[i] - q->skipFlagCount[i])];
        }
    }

    /* calculate bits left, bits needed and adjust bit allocation */
    bits = summer = 0;

    for(i = 0; i < BANDS; i++) {
        if (q->bandFlagsBuf[i]) {
            for(j = band_tab[i]; j < band_tab[i+1]; j++) {
                if(q->skipFlags[j]) {
                    summer += q->CWlengthT[j];
                    q->CWlengthT[j] = 0;
                }
            }
            bits += q->skipFlagBits[i];
            summer -= q->skipFlagBits[i];
        }
    }
    imc_adjust_bit_allocation(q, summer);

    for(i = 0; i < BANDS; i++) {
        q->sumLenArr[i] = 0;

        for(j = band_tab[i]; j < band_tab[i+1]; j++)
            if (!q->skipFlags[j])
                q->sumLenArr[i] += q->CWlengthT[j];
    }

    memset(q->codewords, 0, sizeof(q->codewords));

    if(imc_get_coeffs(q) < 0) {
        av_log(avctx, AV_LOG_ERROR, "Read coefficients failed\n");
        q->decoder_reset = 1;
        return AVERROR_INVALIDDATA;
    }

    if(inverse_quant_coeff(q, stream_format_code) < 0) {
        av_log(avctx, AV_LOG_ERROR, "Inverse quantization of coefficients failed\n");
        q->decoder_reset = 1;
        return AVERROR_INVALIDDATA;
    }

    memset(q->skipFlags, 0, sizeof(q->skipFlags));

    imc_imdct256(q);

    *got_frame_ptr   = 1;
    *(AVFrame *)data = q->frame;

    return IMC_BLOCK_SIZE;
}


static av_cold int imc_decode_close(AVCodecContext * avctx)
{
    IMCContext *q = avctx->priv_data;

    ff_fft_end(&q->fft);

    return 0;
}


AVCodec ff_imc_decoder = {
    .name = "imc",
    .type = AVMEDIA_TYPE_AUDIO,
    .id = CODEC_ID_IMC,
    .priv_data_size = sizeof(IMCContext),
    .init = imc_decode_init,
    .close = imc_decode_close,
    .decode = imc_decode_frame,
    .capabilities = CODEC_CAP_DR1,
    .long_name = NULL_IF_CONFIG_SMALL("IMC (Intel Music Coder)"),
};
OpenPOWER on IntegriCloud