libavcodec/imc.c

   1 /*
   2  * IMC compatible decoder
   3  * Copyright (c) 2002-2004 Maxim Poliakovski
   4  * Copyright (c) 2006 Benjamin Larsson
   5  * Copyright (c) 2006 Konstantin Shishkov
   6  *
   7  * This file is part of FFmpeg.
   8  *
   9  * FFmpeg is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU Lesser General Public
  11  * License as published by the Free Software Foundation; either
  12  * version 2.1 of the License, or (at your option) any later version.
  13  *
  14  * FFmpeg is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  * Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public
  20  * License along with FFmpeg; if not, write to the Free Software
  21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  22  */
  23
  24 /**
  25  *  @file imc.c IMC - Intel Music Coder
  26  *  A mdct based codec using a 256 points large transform
  27  *  divied into 32 bands with some mix of scale factors.
  28  *  Only mono is supported.
  29  *
  30  */
  31
  32
  33 #include <math.h>
  34 #include <stddef.h>
  35 #include <stdio.h>
  36
  37 #define ALT_BITSTREAM_READER
  38 #include "avcodec.h"
  39 #include "bitstream.h"
  40 #include "dsputil.h"
  41
  42 #include "imcdata.h"
  43
  44 #define IMC_BLOCK_SIZE 64
  45 #define IMC_FRAME_ID 0x21
  46 #define BANDS 32
  47 #define COEFFS 256
  48
  49 typedef struct {
  50     float old_floor[BANDS];
  51     float flcoeffs1[BANDS];
  52     float flcoeffs2[BANDS];
  53     float flcoeffs3[BANDS];
  54     float flcoeffs4[BANDS];
  55     float flcoeffs5[BANDS];
  56     float flcoeffs6[BANDS];
  57     float CWdecoded[COEFFS];
  58
  59     /** MDCT tables */
  60     //@{
  61     float mdct_sine_window[COEFFS];
  62     float post_cos[COEFFS];
  63     float post_sin[COEFFS];
  64     float pre_coef1[COEFFS];
  65     float pre_coef2[COEFFS];
  66     float last_fft_im[COEFFS];
  67     //@}
  68
  69     int bandWidthT[BANDS];     ///< codewords per band
  70     int bitsBandT[BANDS];      ///< how many bits per codeword in band
  71     int CWlengthT[COEFFS];     ///< how many bits in each codeword
  72     int levlCoeffBuf[BANDS];
  73     int bandFlagsBuf[BANDS];   ///< flags for each band
  74     int sumLenArr[BANDS];      ///< bits for all coeffs in band
  75     int skipFlagRaw[BANDS];    ///< skip flags are stored in raw form or not
  76     int skipFlagBits[BANDS];   ///< bits used to code skip flags
  77     int skipFlagCount[BANDS];  ///< skipped coeffients per band
  78     int skipFlags[COEFFS];     ///< skip coefficient decoding or not
  79     int codewords[COEFFS];     ///< raw codewords read from bitstream
  80     float sqrt_tab[30];
  81     GetBitContext gb;
  82     VLC huffman_vlc[4][4];
  83     int decoder_reset;
  84     float one_div_log2;
  85
  86     DSPContext dsp;
  87     FFTContext fft;
  88     DECLARE_ALIGNED_16(FFTComplex, samples[COEFFS/2]);
  89     DECLARE_ALIGNED_16(float, out_samples[COEFFS]);
  90 } IMCContext;
  91
  92
  93 static int imc_decode_init(AVCodecContext * avctx)
  94 {
  95     int i, j;
  96     IMCContext *q = avctx->priv_data;
  97     double r1, r2;
  98
  99     q->decoder_reset = 1;
 100
 101     for(i = 0; i < BANDS; i++)
 102         q->old_floor[i] = 1.0;
 103
 104     /* Build mdct window, a simple sine window normalized with sqrt(2) */
 105     for(i = 0; i < COEFFS; i++)
 106         q->mdct_sine_window[i] = sin((i + 0.5) / 512.0 * M_PI) * sqrt(2.0);
 107     for(i = 0; i < COEFFS/2; i++){
 108         q->post_cos[i] = cos(i / 256.0 * M_PI);
 109         q->post_sin[i] = sin(i / 256.0 * M_PI);
 110
 111         r1 = sin((i * 4.0 + 1.0) / 1024.0 * M_PI);
 112         r2 = cos((i * 4.0 + 1.0) / 1024.0 * M_PI);
 113
 114         if (i & 0x1)
 115         {
 116             q->pre_coef1[i] =  (r1 + r2) * sqrt(2.0);
 117             q->pre_coef2[i] = -(r1 - r2) * sqrt(2.0);
 118         }
 119         else
 120         {
 121             q->pre_coef1[i] = -(r1 + r2) * sqrt(2.0);
 122             q->pre_coef2[i] =  (r1 - r2) * sqrt(2.0);
 123         }
 124
 125         q->last_fft_im[i] = 0;
 126     }
 127
 128     /* Generate a square root table */
 129
 130     for(i = 0; i < 30; i++) {
 131         q->sqrt_tab[i] = sqrt(i);
 132     }
 133
 134     /* initialize the VLC tables */
 135     for(i = 0; i < 4 ; i++) {
 136         for(j = 0; j < 4; j++) {
 137             init_vlc (&q->huffman_vlc[i][j], 9, imc_huffman_sizes[i],
 138                      imc_huffman_lens[i][j], 1, 1,
 139                      imc_huffman_bits[i][j], 2, 2, 1);
 140         }
 141     }
 142     q->one_div_log2 = 1/log(2);
 143
 144     ff_fft_init(&q->fft, 7, 1);
 145     dsputil_init(&q->dsp, avctx);
 146     return 0;
 147 }
 148
 149 static void imc_calculate_coeffs(IMCContext* q, float* flcoeffs1, float* flcoeffs2, int* bandWidthT,
 150                                 float* flcoeffs3, float* flcoeffs5)
 151 {
 152     float   workT1[BANDS];
 153     float   workT2[BANDS];
 154     float   workT3[BANDS];
 155     float   snr_limit = 1.e-30;
 156     float   accum = 0.0;
 157     int i, cnt2;
 158
 159     for(i = 0; i < BANDS; i++) {
 160         flcoeffs5[i] = workT2[i] = 0.0;
 161         if (bandWidthT[i]){
 162             workT1[i] = flcoeffs1[i] * flcoeffs1[i];
 163             flcoeffs3[i] = 2.0 * flcoeffs2[i];
 164         } else {
 165             workT1[i] = 0.0;
 166             flcoeffs3[i] = -30000.0;
 167         }
 168         workT3[i] = bandWidthT[i] * workT1[i] * 0.01;
 169         if (workT3[i] <= snr_limit)
 170             workT3[i] = 0.0;
 171     }
 172
 173     for(i = 0; i < BANDS; i++) {
 174         for(cnt2 = i; cnt2 < cyclTab[i]; cnt2++)
 175             flcoeffs5[cnt2] = flcoeffs5[cnt2] + workT3[i];
 176         workT2[cnt2-1] = workT2[cnt2-1] + workT3[i];
 177     }
 178
 179     for(i = 1; i < BANDS; i++) {
 180         accum = (workT2[i-1] + accum) * imc_weights1[i-1];
 181         flcoeffs5[i] += accum;
 182     }
 183
 184     for(i = 0; i < BANDS; i++)
 185         workT2[i] = 0.0;
 186
 187     for(i = 0; i < BANDS; i++) {
 188         for(cnt2 = i-1; cnt2 > cyclTab2[i]; cnt2--)
 189             flcoeffs5[cnt2] += workT3[i];
 190         workT2[cnt2+1] += workT3[i];
 191     }
 192
 193     accum = 0.0;
 194
 195     for(i = BANDS-2; i >= 0; i--) {
 196         accum = (workT2[i+1] + accum) * imc_weights2[i];
 197         flcoeffs5[i] += accum;
 198         //there is missing code here, but it seems to never be triggered
 199     }
 200 }
 201
 202
 203 static void imc_read_level_coeffs(IMCContext* q, int stream_format_code, int* levlCoeffs)
 204 {
 205     int i;
 206     VLC *hufftab[4];
 207     int start = 0;
 208     const uint8_t *cb_sel;
 209     int s;
 210
 211     s = stream_format_code >> 1;
 212     hufftab[0] = &q->huffman_vlc[s][0];
 213     hufftab[1] = &q->huffman_vlc[s][1];
 214     hufftab[2] = &q->huffman_vlc[s][2];
 215     hufftab[3] = &q->huffman_vlc[s][3];
 216     cb_sel = imc_cb_select[s];
 217
 218     if(stream_format_code & 4)
 219         start = 1;
 220     if(start)
 221         levlCoeffs[0] = get_bits(&q->gb, 7);
 222     for(i = start; i < BANDS; i++){
 223         levlCoeffs[i] = get_vlc2(&q->gb, hufftab[cb_sel[i]]->table, hufftab[cb_sel[i]]->bits, 2);
 224         if(levlCoeffs[i] == 17)
 225             levlCoeffs[i] += get_bits(&q->gb, 4);
 226     }
 227 }
 228
 229 static void imc_decode_level_coefficients(IMCContext* q, int* levlCoeffBuf, float* flcoeffs1,
 230                                          float* flcoeffs2)
 231 {
 232     int i, level;
 233     float tmp, tmp2;
 234     //maybe some frequency division thingy
 235
 236     flcoeffs1[0] = 20000.0 / pow (2, levlCoeffBuf[0] * 0.18945); // 0.18945 = log2(10) * 0.05703125
 237     flcoeffs2[0] = log(flcoeffs1[0])/log(2);
 238     tmp = flcoeffs1[0];
 239     tmp2 = flcoeffs2[0];
 240
 241     for(i = 1; i < BANDS; i++) {
 242         level = levlCoeffBuf[i];
 243         if (level == 16) {
 244             flcoeffs1[i] = 1.0;
 245             flcoeffs2[i] = 0.0;
 246         } else {
 247             if (level < 17)
 248                 level -=7;
 249             else if (level <= 24)
 250                 level -=32;
 251             else
 252                 level -=16;
 253
 254             tmp  *= imc_exp_tab[15 + level];
 255             tmp2 += 0.83048 * level;  // 0.83048 = log2(10) * 0.25
 256             flcoeffs1[i] = tmp;
 257             flcoeffs2[i] = tmp2;
 258         }
 259     }
 260 }
 261
 262
 263 static void imc_decode_level_coefficients2(IMCContext* q, int* levlCoeffBuf, float* old_floor, float* flcoeffs1,
 264                                           float* flcoeffs2) {
 265     int i;
 266         //FIXME maybe flag_buf = noise coding and flcoeffs1 = new scale factors
 267         //      and flcoeffs2 old scale factors
 268         //      might be incomplete due to a missing table that is in the binary code
 269     for(i = 0; i < BANDS; i++) {
 270         flcoeffs1[i] = 0;
 271         if(levlCoeffBuf[i] < 16) {
 272             flcoeffs1[i] = imc_exp_tab2[levlCoeffBuf[i]] * old_floor[i];
 273             flcoeffs2[i] = (levlCoeffBuf[i]-7) * 0.83048 + flcoeffs2[i]; // 0.83048 = log2(10) * 0.25
 274         } else {
 275             flcoeffs1[i] = old_floor[i];
 276         }
 277     }
 278 }
 279
 280 /**
 281  * Perform bit allocation depending on bits available
 282  */
 283 static int bit_allocation (IMCContext* q, int stream_format_code, int freebits, int flag) {
 284     int i, j;
 285     const float limit = -1.e20;
 286     float highest = 0.0;
 287     int indx;
 288     int t1 = 0;
 289     int t2 = 1;
 290     float summa = 0.0;
 291     int iacc = 0;
 292     int summer = 0;
 293     int rres, cwlen;
 294     float lowest = 1.e10;
 295     int low_indx = 0;
 296     float workT[32];
 297     int flg;
 298     int found_indx = 0;
 299
 300     for(i = 0; i < BANDS; i++)
 301         highest = FFMAX(highest, q->flcoeffs1[i]);
 302
 303     for(i = 0; i < BANDS-1; i++) {
 304         q->flcoeffs4[i] = q->flcoeffs3[i] - log(q->flcoeffs5[i])/log(2);
 305     }
 306     q->flcoeffs4[BANDS - 1] = limit;
 307
 308     highest = highest * 0.25;
 309
 310     for(i = 0; i < BANDS; i++) {
 311         indx = -1;
 312         if ((band_tab[i+1] - band_tab[i]) == q->bandWidthT[i])
 313             indx = 0;
 314
 315         if ((band_tab[i+1] - band_tab[i]) > q->bandWidthT[i])
 316             indx = 1;
 317
 318         if (((band_tab[i+1] - band_tab[i])/2) >= q->bandWidthT[i])
 319             indx = 2;
 320
 321         if (indx == -1)
 322             return -1;
 323
 324         q->flcoeffs4[i] = q->flcoeffs4[i] + xTab[(indx*2 + (q->flcoeffs1[i] < highest)) * 2 + flag];
 325     }
 326
 327     if (stream_format_code & 0x2) {
 328         q->flcoeffs4[0] = limit;
 329         q->flcoeffs4[1] = limit;
 330         q->flcoeffs4[2] = limit;
 331         q->flcoeffs4[3] = limit;
 332     }
 333
 334     for(i = (stream_format_code & 0x2)?4:0; i < BANDS-1; i++) {
 335         iacc += q->bandWidthT[i];
 336         summa += q->bandWidthT[i] * q->flcoeffs4[i];
 337     }
 338     q->bandWidthT[BANDS-1] = 0;
 339     summa = (summa * 0.5 - freebits) / iacc;
 340
 341
 342     for(i = 0; i < BANDS/2; i++) {
 343         rres = summer - freebits;
 344         if((rres >= -8) && (rres <= 8)) break;
 345
 346         summer = 0;
 347         iacc = 0;
 348
 349         for(j = (stream_format_code & 0x2)?4:0; j < BANDS; j++) {
 350             cwlen = av_clip((int)((q->flcoeffs4[j] * 0.5) - summa + 0.5), 0, 6);
 351
 352             q->bitsBandT[j] = cwlen;
 353             summer += q->bandWidthT[j] * cwlen;
 354
 355             if (cwlen > 0)
 356                 iacc += q->bandWidthT[j];
 357         }
 358
 359         flg = t2;
 360         t2 = 1;
 361         if (freebits < summer)
 362             t2 = -1;
 363         if (i == 0)
 364             flg = t2;
 365         if(flg != t2)
 366             t1++;
 367
 368         summa = (float)(summer - freebits) / ((t1 + 1) * iacc) + summa;
 369     }
 370
 371     for(i = (stream_format_code & 0x2)?4:0; i < BANDS; i++) {
 372         for(j = band_tab[i]; j < band_tab[i+1]; j++)
 373             q->CWlengthT[j] = q->bitsBandT[i];
 374     }
 375
 376     if (freebits > summer) {
 377         for(i = 0; i < BANDS; i++) {
 378             workT[i] = (q->bitsBandT[i] == 6) ? -1.e20 : (q->bitsBandT[i] * -2 + q->flcoeffs4[i] - 0.415);
 379         }
 380
 381         highest = 0.0;
 382
 383         do{
 384             if (highest <= -1.e20)
 385                 break;
 386
 387             found_indx = 0;
 388             highest = -1.e20;
 389
 390             for(i = 0; i < BANDS; i++) {
 391                 if (workT[i] > highest) {
 392                     highest = workT[i];
 393                     found_indx = i;
 394                 }
 395             }
 396
 397             if (highest > -1.e20) {
 398                 workT[found_indx] -= 2.0;
 399                 if (++(q->bitsBandT[found_indx]) == 6)
 400                     workT[found_indx] = -1.e20;
 401
 402                 for(j = band_tab[found_indx]; j < band_tab[found_indx+1] && (freebits > summer); j++){
 403                     q->CWlengthT[j]++;
 404                     summer++;
 405                 }
 406             }
 407         }while (freebits > summer);
 408     }
 409     if (freebits < summer) {
 410         for(i = 0; i < BANDS; i++) {
 411             workT[i] = q->bitsBandT[i] ? (q->bitsBandT[i] * -2 + q->flcoeffs4[i] + 1.585) : 1.e20;
 412         }
 413         if (stream_format_code & 0x2) {
 414             workT[0] = 1.e20;
 415             workT[1] = 1.e20;
 416             workT[2] = 1.e20;
 417             workT[3] = 1.e20;
 418         }
 419         while (freebits < summer){
 420             lowest = 1.e10;
 421             low_indx = 0;
 422             for(i = 0; i < BANDS; i++) {
 423                 if (workT[i] < lowest) {
 424                     lowest = workT[i];
 425                     low_indx = i;
 426                 }
 427             }
 428             //if(lowest >= 1.e10) break;
 429             workT[low_indx] = lowest + 2.0;
 430
 431             if (!(--q->bitsBandT[low_indx]))
 432                 workT[low_indx] = 1.e20;
 433
 434             for(j = band_tab[low_indx]; j < band_tab[low_indx+1] && (freebits < summer); j++){
 435                 if(q->CWlengthT[j] > 0){
 436                     q->CWlengthT[j]--;
 437                     summer--;
 438                 }
 439             }
 440         }
 441     }
 442     return 0;
 443 }
 444
 445 static void imc_get_skip_coeff(IMCContext* q) {
 446     int i, j;
 447
 448     memset(q->skipFlagBits, 0, sizeof(q->skipFlagBits));
 449     memset(q->skipFlagCount, 0, sizeof(q->skipFlagCount));
 450     for(i = 0; i < BANDS; i++) {
 451         if (!q->bandFlagsBuf[i] || !q->bandWidthT[i])
 452             continue;
 453
 454         if (!q->skipFlagRaw[i]) {
 455             q->skipFlagBits[i] = band_tab[i+1] - band_tab[i];
 456
 457             for(j = band_tab[i]; j < band_tab[i+1]; j++) {
 458                 if ((q->skipFlags[j] = get_bits1(&q->gb)))
 459                     q->skipFlagCount[i]++;
 460             }
 461         } else {
 462             for(j = band_tab[i]; j < (band_tab[i+1]-1); j += 2) {
 463                 if(!get_bits1(&q->gb)){//0
 464                     q->skipFlagBits[i]++;
 465                     q->skipFlags[j]=1;
 466                     q->skipFlags[j+1]=1;
 467                     q->skipFlagCount[i] += 2;
 468                 }else{
 469                     if(get_bits1(&q->gb)){//11
 470                         q->skipFlagBits[i] +=2;
 471                         q->skipFlags[j]=0;
 472                         q->skipFlags[j+1]=1;
 473                         q->skipFlagCount[i]++;
 474                     }else{
 475                         q->skipFlagBits[i] +=3;
 476                         q->skipFlags[j+1]=0;
 477                         if(!get_bits1(&q->gb)){//100
 478                             q->skipFlags[j]=1;
 479                             q->skipFlagCount[i]++;
 480                         }else{//101
 481                             q->skipFlags[j]=0;
 482                         }
 483                     }
 484                 }
 485             }
 486
 487             if (j < band_tab[i+1]) {
 488                 q->skipFlagBits[i]++;
 489                 if ((q->skipFlags[j] = get_bits1(&q->gb)))
 490                     q->skipFlagCount[i]++;
 491             }
 492         }
 493     }
 494 }
 495
 496 /**
 497  * Increase highest' band coefficient sizes as some bits won't be used
 498  */
 499 static void imc_adjust_bit_allocation (IMCContext* q, int summer) {
 500     float workT[32];
 501     int corrected = 0;
 502     int i, j;
 503     float highest = 0;
 504     int found_indx=0;
 505
 506     for(i = 0; i < BANDS; i++) {
 507         workT[i] = (q->bitsBandT[i] == 6) ? -1.e20 : (q->bitsBandT[i] * -2 + q->flcoeffs4[i] - 0.415);
 508     }
 509
 510     while (corrected < summer) {
 511         if(highest <= -1.e20)
 512             break;
 513
 514         highest = -1.e20;
 515
 516         for(i = 0; i < BANDS; i++) {
 517             if (workT[i] > highest) {
 518                 highest = workT[i];
 519                 found_indx = i;
 520             }
 521         }
 522
 523         if (highest > -1.e20) {
 524             workT[found_indx] -= 2.0;
 525             if (++(q->bitsBandT[found_indx]) == 6)
 526                 workT[found_indx] = -1.e20;
 527
 528             for(j = band_tab[found_indx]; j < band_tab[found_indx+1] && (corrected < summer); j++) {
 529                 if (!q->skipFlags[j] && (q->CWlengthT[j] < 6)) {
 530                     q->CWlengthT[j]++;
 531                     corrected++;
 532                 }
 533             }
 534         }
 535     }
 536 }
 537
 538 static void imc_imdct256(IMCContext *q) {
 539     int i;
 540     float re, im;
 541
 542     /* prerotation */
 543     for(i=0; i < COEFFS/2; i++){
 544         q->samples[i].re = -(q->pre_coef1[i] * q->CWdecoded[COEFFS-1-i*2]) -
 545                            (q->pre_coef2[i] * q->CWdecoded[i*2]);
 546         q->samples[i].im = (q->pre_coef2[i] * q->CWdecoded[COEFFS-1-i*2]) -
 547                            (q->pre_coef1[i] * q->CWdecoded[i*2]);
 548     }
 549
 550     /* FFT */
 551     ff_fft_permute(&q->fft, q->samples);
 552     ff_fft_calc (&q->fft, q->samples);
 553
 554     /* postrotation, window and reorder */
 555     for(i = 0; i < COEFFS/2; i++){
 556         re = (q->samples[i].re * q->post_cos[i]) + (-q->samples[i].im * q->post_sin[i]);
 557         im = (-q->samples[i].im * q->post_cos[i]) - (q->samples[i].re * q->post_sin[i]);
 558         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);
 559         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);
 560         q->last_fft_im[i] = im;
 561     }
 562 }
 563
 564 static int inverse_quant_coeff (IMCContext* q, int stream_format_code) {
 565     int i, j;
 566     int middle_value, cw_len, max_size;
 567     const float* quantizer;
 568
 569     for(i = 0; i < BANDS; i++) {
 570         for(j = band_tab[i]; j < band_tab[i+1]; j++) {
 571             q->CWdecoded[j] = 0;
 572             cw_len = q->CWlengthT[j];
 573
 574             if (cw_len <= 0 || q->skipFlags[j])
 575                 continue;
 576
 577             max_size = 1 << cw_len;
 578             middle_value = max_size >> 1;
 579
 580             if (q->codewords[j] >= max_size || q->codewords[j] < 0)
 581                 return -1;
 582
 583             if (cw_len >= 4){
 584                 quantizer = imc_quantizer2[(stream_format_code & 2) >> 1];
 585                 if (q->codewords[j] >= middle_value)
 586                     q->CWdecoded[j] = quantizer[q->codewords[j] - 8] * q->flcoeffs6[i];
 587                 else
 588                     q->CWdecoded[j] = -quantizer[max_size - q->codewords[j] - 8 - 1] * q->flcoeffs6[i];
 589             }else{
 590                 quantizer = imc_quantizer1[((stream_format_code & 2) >> 1) | (q->bandFlagsBuf[i] << 1)];
 591                 if (q->codewords[j] >= middle_value)
 592                     q->CWdecoded[j] = quantizer[q->codewords[j] - 1] * q->flcoeffs6[i];
 593                 else
 594                     q->CWdecoded[j] = -quantizer[max_size - 2 - q->codewords[j]] * q->flcoeffs6[i];
 595             }
 596         }
 597     }
 598     return 0;
 599 }
 600
 601
 602 static int imc_get_coeffs (IMCContext* q) {
 603     int i, j, cw_len, cw;
 604
 605     for(i = 0; i < BANDS; i++) {
 606         if(!q->sumLenArr[i]) continue;
 607         if (q->bandFlagsBuf[i] || q->bandWidthT[i]) {
 608             for(j = band_tab[i]; j < band_tab[i+1]; j++) {
 609                 cw_len = q->CWlengthT[j];
 610                 cw = 0;
 611
 612                 if (get_bits_count(&q->gb) + cw_len > 512){
 613 //av_log(NULL,0,"Band %i coeff %i cw_len %i\n",i,j,cw_len);
 614                     return -1;
 615                 }
 616
 617                 if(cw_len && (!q->bandFlagsBuf[i] || !q->skipFlags[j]))
 618                     cw = get_bits(&q->gb, cw_len);
 619
 620                 q->codewords[j] = cw;
 621             }
 622         }
 623     }
 624     return 0;
 625 }
 626
 627 static int imc_decode_frame(AVCodecContext * avctx,
 628                             void *data, int *data_size,
 629                             const uint8_t * buf, int buf_size)
 630 {
 631
 632     IMCContext *q = avctx->priv_data;
 633
 634     int stream_format_code;
 635     int imc_hdr, i, j;
 636     int flag;
 637     int bits, summer;
 638     int counter, bitscount;
 639     uint16_t buf16[IMC_BLOCK_SIZE / 2];
 640
 641     if (buf_size < IMC_BLOCK_SIZE) {
 642         av_log(avctx, AV_LOG_ERROR, "imc frame too small!\n");
 643         return -1;
 644     }
 645     for(i = 0; i < IMC_BLOCK_SIZE / 2; i++)
 646         buf16[i] = bswap_16(((const uint16_t*)buf)[i]);
 647
 648     init_get_bits(&q->gb, (const uint8_t*)buf16, IMC_BLOCK_SIZE * 8);
 649
 650     /* Check the frame header */
 651     imc_hdr = get_bits(&q->gb, 9);
 652     if (imc_hdr != IMC_FRAME_ID) {
 653         av_log(avctx, AV_LOG_ERROR, "imc frame header check failed!\n");
 654         av_log(avctx, AV_LOG_ERROR, "got %x instead of 0x21.\n", imc_hdr);
 655         return -1;
 656     }
 657     stream_format_code = get_bits(&q->gb, 3);
 658
 659     if(stream_format_code & 1){
 660         av_log(avctx, AV_LOG_ERROR, "Stream code format %X is not supported\n", stream_format_code);
 661         return -1;
 662     }
 663
 664 //    av_log(avctx, AV_LOG_DEBUG, "stream_format_code = %d\n", stream_format_code);
 665
 666     if (stream_format_code & 0x04)
 667         q->decoder_reset = 1;
 668
 669     if(q->decoder_reset) {
 670         memset(q->out_samples, 0, sizeof(q->out_samples));
 671         for(i = 0; i < BANDS; i++)q->old_floor[i] = 1.0;
 672         for(i = 0; i < COEFFS; i++)q->CWdecoded[i] = 0;
 673         q->decoder_reset = 0;
 674     }
 675
 676     flag = get_bits1(&q->gb);
 677     imc_read_level_coeffs(q, stream_format_code, q->levlCoeffBuf);
 678
 679     if (stream_format_code & 0x4)
 680         imc_decode_level_coefficients(q, q->levlCoeffBuf, q->flcoeffs1, q->flcoeffs2);
 681     else
 682         imc_decode_level_coefficients2(q, q->levlCoeffBuf, q->old_floor, q->flcoeffs1, q->flcoeffs2);
 683
 684     memcpy(q->old_floor, q->flcoeffs1, 32 * sizeof(float));
 685
 686     counter = 0;
 687     for (i=0 ; i<BANDS ; i++) {
 688         if (q->levlCoeffBuf[i] == 16) {
 689             q->bandWidthT[i] = 0;
 690             counter++;
 691         } else
 692             q->bandWidthT[i] = band_tab[i+1] - band_tab[i];
 693     }
 694     memset(q->bandFlagsBuf, 0, BANDS * sizeof(int));
 695     for(i = 0; i < BANDS-1; i++) {
 696         if (q->bandWidthT[i])
 697             q->bandFlagsBuf[i] = get_bits1(&q->gb);
 698     }
 699
 700     imc_calculate_coeffs(q, q->flcoeffs1, q->flcoeffs2, q->bandWidthT, q->flcoeffs3, q->flcoeffs5);
 701
 702     bitscount = 0;
 703     /* first 4 bands will be assigned 5 bits per coefficient */
 704     if (stream_format_code & 0x2) {
 705         bitscount += 15;
 706
 707         q->bitsBandT[0] = 5;
 708         q->CWlengthT[0] = 5;
 709         q->CWlengthT[1] = 5;
 710         q->CWlengthT[2] = 5;
 711         for(i = 1; i < 4; i++){
 712             bits = (q->levlCoeffBuf[i] == 16) ? 0 : 5;
 713             q->bitsBandT[i] = bits;
 714             for(j = band_tab[i]; j < band_tab[i+1]; j++) {
 715                 q->CWlengthT[j] = bits;
 716                 bitscount += bits;
 717             }
 718         }
 719     }
 720
 721     if(bit_allocation (q, stream_format_code, 512 - bitscount - get_bits_count(&q->gb), flag) < 0) {
 722         av_log(avctx, AV_LOG_ERROR, "Bit allocations failed\n");
 723         q->decoder_reset = 1;
 724         return -1;
 725     }
 726
 727     for(i = 0; i < BANDS; i++) {
 728         q->sumLenArr[i] = 0;
 729         q->skipFlagRaw[i] = 0;
 730         for(j = band_tab[i]; j < band_tab[i+1]; j++)
 731             q->sumLenArr[i] += q->CWlengthT[j];
 732         if (q->bandFlagsBuf[i])
 733             if( (((band_tab[i+1] - band_tab[i]) * 1.5) > q->sumLenArr[i]) && (q->sumLenArr[i] > 0))
 734                 q->skipFlagRaw[i] = 1;
 735     }
 736
 737     imc_get_skip_coeff(q);
 738
 739     for(i = 0; i < BANDS; i++) {
 740         q->flcoeffs6[i] = q->flcoeffs1[i];
 741         /* band has flag set and at least one coded coefficient */
 742         if (q->bandFlagsBuf[i] && (band_tab[i+1] - band_tab[i]) != q->skipFlagCount[i]){
 743                 q->flcoeffs6[i] *= q->sqrt_tab[band_tab[i+1] - band_tab[i]] /
 744                                    q->sqrt_tab[(band_tab[i+1] - band_tab[i] - q->skipFlagCount[i])];
 745         }
 746     }
 747
 748     /* calculate bits left, bits needed and adjust bit allocation */
 749     bits = summer = 0;
 750
 751     for(i = 0; i < BANDS; i++) {
 752         if (q->bandFlagsBuf[i]) {
 753             for(j = band_tab[i]; j < band_tab[i+1]; j++) {
 754                 if(q->skipFlags[j]) {
 755                     summer += q->CWlengthT[j];
 756                     q->CWlengthT[j] = 0;
 757                 }
 758             }
 759             bits += q->skipFlagBits[i];
 760             summer -= q->skipFlagBits[i];
 761         }
 762     }
 763     imc_adjust_bit_allocation(q, summer);
 764
 765     for(i = 0; i < BANDS; i++) {
 766         q->sumLenArr[i] = 0;
 767
 768         for(j = band_tab[i]; j < band_tab[i+1]; j++)
 769             if (!q->skipFlags[j])
 770                 q->sumLenArr[i] += q->CWlengthT[j];
 771     }
 772
 773     memset(q->codewords, 0, sizeof(q->codewords));
 774
 775     if(imc_get_coeffs(q) < 0) {
 776         av_log(avctx, AV_LOG_ERROR, "Read coefficients failed\n");
 777         q->decoder_reset = 1;
 778         return 0;
 779     }
 780
 781     if(inverse_quant_coeff(q, stream_format_code) < 0) {
 782         av_log(avctx, AV_LOG_ERROR, "Inverse quantization of coefficients failed\n");
 783         q->decoder_reset = 1;
 784         return 0;
 785     }
 786
 787     memset(q->skipFlags, 0, sizeof(q->skipFlags));
 788
 789     imc_imdct256(q);
 790
 791     q->dsp.float_to_int16(data, q->out_samples, COEFFS);
 792
 793     *data_size = COEFFS * sizeof(int16_t);
 794
 795     return IMC_BLOCK_SIZE;
 796 }
 797
 798
 799 static int imc_decode_close(AVCodecContext * avctx)
 800 {
 801     IMCContext *q = avctx->priv_data;
 802
 803     ff_fft_end(&q->fft);
 804     return 0;
 805 }
 806
 807
 808 AVCodec imc_decoder = {
 809     .name = "imc",
 810     .type = CODEC_TYPE_AUDIO,
 811     .id = CODEC_ID_IMC,
 812     .priv_data_size = sizeof(IMCContext),
 813     .init = imc_decode_init,
 814     .close = imc_decode_close,
 815     .decode = imc_decode_frame,
 816 };