aboutsummaryrefslogblamecommitdiffstats
path: root/libavcodec/atrac3plus.c
blob: 3e3bba801b91fb8c9c2ff62bd9faf5897f1dfa09 (plain) (tree)
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574







































                                                                               








































                                                                                

                                                     

                                                     
                                                

                                                     
                                                

                                                                

                                                     

                                                     
                                                

                                                     
                                                

                                               
                                                                         
                                                 


                                                                            
                                                 


                                                                            
                                                 


                                                                 
                                                 





                                                                     
                                                   





                                                                           
                                                



                                                               
                                                  





























































































                                                                                         
                                                             






































































































































                                                                                
                                                                                    

































































































































                                                                                   
                                                                            















                                                                               
                                                                            



























































































































































































































































































                                                                                    
                 





                                                                     
                                                  























































































































































































                                                                                                    
                                                                                    





















































































































                                                                             
                                                                                          






















































































































































































































































































































































































































































                                                                                             
                             



























































































































                                                                                               


                                                                             

















                                                                                              
                                                                                              





















































































                                                                                    
/*
 * ATRAC3+ compatible decoder
 *
 * Copyright (c) 2010-2013 Maxim Poliakovski
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg 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.
 *
 * FFmpeg 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 FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

/**
 * @file
 * Bitstream parser for ATRAC3+ decoder.
 */

#include "libavutil/avassert.h"
#include "avcodec.h"
#include "get_bits.h"
#include "atrac3plus.h"
#include "atrac3plus_data.h"

static VLC_TYPE tables_data[154276][2];
static VLC wl_vlc_tabs[4];
static VLC sf_vlc_tabs[8];
static VLC ct_vlc_tabs[4];
static VLC spec_vlc_tabs[112];
static VLC gain_vlc_tabs[11];
static VLC tone_vlc_tabs[7];

/**
 * Generate canonical VLC table from given descriptor.
 *
 * @param[in]     cb          ptr to codebook descriptor
 * @param[in]     xlat        ptr to translation table or NULL
 * @param[in,out] tab_offset  starting offset to the generated vlc table
 * @param[out]    out_vlc     ptr to vlc table to be generated
 */
static av_cold void build_canonical_huff(const uint8_t *cb, const uint8_t *xlat,
                                         int *tab_offset, VLC *out_vlc)
{
    int i, b;
    uint16_t codes[256];
    uint8_t bits[256];
    unsigned code = 0;
    int index = 0;
    int min_len = *cb++; // get shortest codeword length
    int max_len = *cb++; // get longest  codeword length

    for (b = min_len; b <= max_len; b++) {
        for (i = *cb++; i > 0; i--) {
            av_assert0(index < 256);
            bits[index]  = b;
            codes[index] = code++;
            index++;
        }
        code <<= 1;
    }

    out_vlc->table = &tables_data[*tab_offset];
    out_vlc->table_allocated = 1 << max_len;

    ff_init_vlc_sparse(out_vlc, max_len, index, bits, 1, 1, codes, 2, 2,
                       xlat, 1, 1, INIT_VLC_USE_NEW_STATIC);

    *tab_offset += 1 << max_len;
}

av_cold void ff_atrac3p_init_vlcs(void)
{
    int i, wl_vlc_offs, ct_vlc_offs, sf_vlc_offs, tab_offset;

    static const int wl_nb_bits[4]  = { 2, 3, 5, 5 };
    static const int wl_nb_codes[4] = { 3, 5, 8, 8 };
    static const uint8_t * const wl_bits[4] = {
        atrac3p_wl_huff_bits1, atrac3p_wl_huff_bits2,
        atrac3p_wl_huff_bits3, atrac3p_wl_huff_bits4
    };
    static const uint8_t * const wl_codes[4] = {
        atrac3p_wl_huff_code1, atrac3p_wl_huff_code2,
        atrac3p_wl_huff_code3, atrac3p_wl_huff_code4
    };
    static const uint8_t * const wl_xlats[4] = {
        atrac3p_wl_huff_xlat1, atrac3p_wl_huff_xlat2, NULL, NULL
    };

    static const int ct_nb_bits[4]  = { 3, 4, 4, 4 };
    static const int ct_nb_codes[4] = { 4, 8, 8, 8 };
    static const uint8_t * const ct_bits[4]  = {
        atrac3p_ct_huff_bits1, atrac3p_ct_huff_bits2,
        atrac3p_ct_huff_bits2, atrac3p_ct_huff_bits3
    };
    static const uint8_t * const ct_codes[4] = {
        atrac3p_ct_huff_code1, atrac3p_ct_huff_code2,
        atrac3p_ct_huff_code2, atrac3p_ct_huff_code3
    };
    static const uint8_t * const ct_xlats[4] = {
        NULL, NULL, atrac3p_ct_huff_xlat1, NULL
    };

    static const int sf_nb_bits[8]  = {  9,  9,  9,  9,  6,  6,  7,  7 };
    static const int sf_nb_codes[8] = { 64, 64, 64, 64, 16, 16, 16, 16 };
    static const uint8_t  * const sf_bits[8]  = {
        atrac3p_sf_huff_bits1, atrac3p_sf_huff_bits1, atrac3p_sf_huff_bits2,
        atrac3p_sf_huff_bits3, atrac3p_sf_huff_bits4, atrac3p_sf_huff_bits4,
        atrac3p_sf_huff_bits5, atrac3p_sf_huff_bits6
    };
    static const uint16_t * const sf_codes[8] = {
        atrac3p_sf_huff_code1, atrac3p_sf_huff_code1, atrac3p_sf_huff_code2,
        atrac3p_sf_huff_code3, atrac3p_sf_huff_code4, atrac3p_sf_huff_code4,
        atrac3p_sf_huff_code5, atrac3p_sf_huff_code6
    };
    static const uint8_t  * const sf_xlats[8] = {
        atrac3p_sf_huff_xlat1, atrac3p_sf_huff_xlat2, NULL, NULL,
        atrac3p_sf_huff_xlat4, atrac3p_sf_huff_xlat5, NULL, NULL
    };

    static const uint8_t * const gain_cbs[11] = {
        atrac3p_huff_gain_npoints1_cb, atrac3p_huff_gain_npoints1_cb,
        atrac3p_huff_gain_lev1_cb, atrac3p_huff_gain_lev2_cb,
        atrac3p_huff_gain_lev3_cb, atrac3p_huff_gain_lev4_cb,
        atrac3p_huff_gain_loc3_cb, atrac3p_huff_gain_loc1_cb,
        atrac3p_huff_gain_loc4_cb, atrac3p_huff_gain_loc2_cb,
        atrac3p_huff_gain_loc5_cb
    };
    static const uint8_t * const gain_xlats[11] = {
        NULL, atrac3p_huff_gain_npoints2_xlat, atrac3p_huff_gain_lev1_xlat,
        atrac3p_huff_gain_lev2_xlat, atrac3p_huff_gain_lev3_xlat,
        atrac3p_huff_gain_lev4_xlat, atrac3p_huff_gain_loc3_xlat,
        atrac3p_huff_gain_loc1_xlat, atrac3p_huff_gain_loc4_xlat,
        atrac3p_huff_gain_loc2_xlat, atrac3p_huff_gain_loc5_xlat
    };

    static const uint8_t * const tone_cbs[7] = {
        atrac3p_huff_tonebands_cb,  atrac3p_huff_numwavs1_cb,
        atrac3p_huff_numwavs2_cb,   atrac3p_huff_wav_ampsf1_cb,
        atrac3p_huff_wav_ampsf2_cb, atrac3p_huff_wav_ampsf3_cb,
        atrac3p_huff_freq_cb
    };
    static const uint8_t * const tone_xlats[7] = {
        NULL, NULL, atrac3p_huff_numwavs2_xlat, atrac3p_huff_wav_ampsf1_xlat,
        atrac3p_huff_wav_ampsf2_xlat, atrac3p_huff_wav_ampsf3_xlat,
        atrac3p_huff_freq_xlat
    };

    for (i = 0, wl_vlc_offs = 0, ct_vlc_offs = 2508; i < 4; i++) {
        wl_vlc_tabs[i].table = &tables_data[wl_vlc_offs];
        wl_vlc_tabs[i].table_allocated = 1 << wl_nb_bits[i];
        ct_vlc_tabs[i].table = &tables_data[ct_vlc_offs];
        ct_vlc_tabs[i].table_allocated = 1 << ct_nb_bits[i];

        ff_init_vlc_sparse(&wl_vlc_tabs[i], wl_nb_bits[i], wl_nb_codes[i],
                           wl_bits[i],  1, 1,
                           wl_codes[i], 1, 1,
                           wl_xlats[i], 1, 1,
                           INIT_VLC_USE_NEW_STATIC);

        ff_init_vlc_sparse(&ct_vlc_tabs[i], ct_nb_bits[i], ct_nb_codes[i],
                           ct_bits[i],  1, 1,
                           ct_codes[i], 1, 1,
                           ct_xlats[i], 1, 1,
                           INIT_VLC_USE_NEW_STATIC);

        wl_vlc_offs += wl_vlc_tabs[i].table_allocated;
        ct_vlc_offs += ct_vlc_tabs[i].table_allocated;
    }

    for (i = 0, sf_vlc_offs = 76; i < 8; i++) {
        sf_vlc_tabs[i].table = &tables_data[sf_vlc_offs];
        sf_vlc_tabs[i].table_allocated = 1 << sf_nb_bits[i];

        ff_init_vlc_sparse(&sf_vlc_tabs[i], sf_nb_bits[i], sf_nb_codes[i],
                           sf_bits[i],  1, 1,
                           sf_codes[i], 2, 2,
                           sf_xlats[i], 1, 1,
                           INIT_VLC_USE_NEW_STATIC);
        sf_vlc_offs += sf_vlc_tabs[i].table_allocated;
    }

    tab_offset = 2564;

    /* build huffman tables for spectrum decoding */
    for (i = 0; i < 112; i++) {
        if (atrac3p_spectra_tabs[i].cb)
            build_canonical_huff(atrac3p_spectra_tabs[i].cb,
                                 atrac3p_spectra_tabs[i].xlat,
                                 &tab_offset, &spec_vlc_tabs[i]);
        else
            spec_vlc_tabs[i].table = 0;
    }

    /* build huffman tables for gain data decoding */
    for (i = 0; i < 11; i++)
        build_canonical_huff(gain_cbs[i], gain_xlats[i], &tab_offset, &gain_vlc_tabs[i]);

    /* build huffman tables for tone decoding */
    for (i = 0; i < 7; i++)
        build_canonical_huff(tone_cbs[i], tone_xlats[i], &tab_offset, &tone_vlc_tabs[i]);
}

/**
 * Decode number of coded quantization units.
 *
 * @param[in]     gb            the GetBit context
 * @param[in,out] chan          ptr to the channel parameters
 * @param[in,out] ctx           ptr to the channel unit context
 * @param[in]     avctx         ptr to the AVCodecContext
 * @return result code: 0 = OK, otherwise - error code
 */
static int num_coded_units(GetBitContext *gb, Atrac3pChanParams *chan,
                           Atrac3pChanUnitCtx *ctx, AVCodecContext *avctx)
{
    chan->fill_mode = get_bits(gb, 2);
    if (!chan->fill_mode) {
        chan->num_coded_vals = ctx->num_quant_units;
    } else {
        chan->num_coded_vals = get_bits(gb, 5);
        if (chan->num_coded_vals > ctx->num_quant_units) {
            av_log(avctx, AV_LOG_ERROR,
                   "Invalid number of transmitted units!\n");
            return AVERROR_INVALIDDATA;
        }

        if (chan->fill_mode == 3)
            chan->split_point = get_bits(gb, 2) + (chan->ch_num << 1) + 1;
    }

    return 0;
}

/**
 * Add weighting coefficients to the decoded word-length information.
 *
 * @param[in,out] ctx           ptr to the channel unit context
 * @param[in,out] chan          ptr to the channel parameters
 * @param[in]     wtab_idx      index of the table of weights
 * @param[in]     avctx         ptr to the AVCodecContext
 * @return result code: 0 = OK, otherwise - error code
 */
static int add_wordlen_weights(Atrac3pChanUnitCtx *ctx,
                               Atrac3pChanParams *chan, int wtab_idx,
                               AVCodecContext *avctx)
{
    int i;
    const int8_t *weights_tab =
        &atrac3p_wl_weights[chan->ch_num * 3 + wtab_idx - 1][0];

    for (i = 0; i < ctx->num_quant_units; i++) {
        chan->qu_wordlen[i] += weights_tab[i];
        if (chan->qu_wordlen[i] < 0 || chan->qu_wordlen[i] > 7) {
            av_log(avctx, AV_LOG_ERROR,
                   "WL index out of range: pos=%d, val=%d!\n",
                   i, chan->qu_wordlen[i]);
            return AVERROR_INVALIDDATA;
        }
    }

    return 0;
}

/**
 * Subtract weighting coefficients from decoded scalefactors.
 *
 * @param[in,out] ctx           ptr to the channel unit context
 * @param[in,out] chan          ptr to the channel parameters
 * @param[in]     wtab_idx      index of table of weights
 * @param[in]     avctx         ptr to the AVCodecContext
 * @return result code: 0 = OK, otherwise - error code
 */
static int subtract_sf_weights(Atrac3pChanUnitCtx *ctx,
                               Atrac3pChanParams *chan, int wtab_idx,
                               AVCodecContext *avctx)
{
    int i;
    const int8_t *weights_tab = &atrac3p_sf_weights[wtab_idx - 1][0];

    for (i = 0; i < ctx->used_quant_units; i++) {
        chan->qu_sf_idx[i] -= weights_tab[i];
        if (chan->qu_sf_idx[i] < 0 || chan->qu_sf_idx[i] > 63) {
            av_log(avctx, AV_LOG_ERROR,
                   "SF index out of range: pos=%d, val=%d!\n",
                   i, chan->qu_sf_idx[i]);
            return AVERROR_INVALIDDATA;
        }
    }

    return 0;
}

/**
 * Unpack vector quantization tables.
 *
 * @param[in]    start_val    start value for the unpacked table
 * @param[in]    shape_vec    ptr to table to unpack
 * @param[out]   dst          ptr to output array
 * @param[in]    num_values   number of values to unpack
 */
static inline void unpack_vq_shape(int start_val, const int8_t *shape_vec,
                                   int *dst, int num_values)
{
    int i;

    if (num_values) {
        dst[0] = dst[1] = dst[2] = start_val;
        for (i = 3; i < num_values; i++)
            dst[i] = start_val - shape_vec[atrac3p_qu_num_to_seg[i] - 1];
    }
}

#define UNPACK_SF_VQ_SHAPE(gb, dst, num_vals)                            \
    start_val = get_bits((gb), 6);                                       \
    unpack_vq_shape(start_val, &atrac3p_sf_shapes[get_bits((gb), 6)][0], \
                    (dst), (num_vals))

/**
 * Decode word length for each quantization unit of a channel.
 *
 * @param[in]     gb            the GetBit context
 * @param[in,out] ctx           ptr to the channel unit context
 * @param[in]     ch_num        channel to process
 * @param[in]     avctx         ptr to the AVCodecContext
 * @return result code: 0 = OK, otherwise - error code
 */
static int decode_channel_wordlen(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
                                  int ch_num, AVCodecContext *avctx)
{
    int i, weight_idx = 0, delta, diff, pos, delta_bits, min_val, flag,
        ret, start_val;
    VLC *vlc_tab;
    Atrac3pChanParams *chan     = &ctx->channels[ch_num];
    Atrac3pChanParams *ref_chan = &ctx->channels[0];

    chan->fill_mode = 0;

    switch (get_bits(gb, 2)) { /* switch according to coding mode */
    case 0: /* coded using constant number of bits */
        for (i = 0; i < ctx->num_quant_units; i++)
            chan->qu_wordlen[i] = get_bits(gb, 3);
        break;
    case 1:
        if (ch_num) {
            if ((ret = num_coded_units(gb, chan, ctx, avctx)) < 0)
                return ret;

            if (chan->num_coded_vals) {
                vlc_tab = &wl_vlc_tabs[get_bits(gb, 2)];

                for (i = 0; i < chan->num_coded_vals; i++) {
                    delta = get_vlc2(gb, vlc_tab->table, vlc_tab->bits, 1);
                    chan->qu_wordlen[i] = (ref_chan->qu_wordlen[i] + delta) & 7;
                }
            }
        } else {
            weight_idx = get_bits(gb, 2);
            if ((ret = num_coded_units(gb, chan, ctx, avctx)) < 0)
                return ret;

            if (chan->num_coded_vals) {
                pos = get_bits(gb, 5);
                if (pos > chan->num_coded_vals) {
                    av_log(avctx, AV_LOG_ERROR,
                           "WL mode 1: invalid position!\n");
                    return AVERROR_INVALIDDATA;
                }

                delta_bits = get_bits(gb, 2);
                min_val    = get_bits(gb, 3);

                for (i = 0; i < pos; i++)
                    chan->qu_wordlen[i] = get_bits(gb, 3);

                for (i = pos; i < chan->num_coded_vals; i++)
                    chan->qu_wordlen[i] = (min_val + get_bitsz(gb, delta_bits)) & 7;
            }
        }
        break;
    case 2:
        if ((ret = num_coded_units(gb, chan, ctx, avctx)) < 0)
            return ret;

        if (ch_num && chan->num_coded_vals) {
            vlc_tab = &wl_vlc_tabs[get_bits(gb, 2)];
            delta = get_vlc2(gb, vlc_tab->table, vlc_tab->bits, 1);
            chan->qu_wordlen[0] = (ref_chan->qu_wordlen[0] + delta) & 7;

            for (i = 1; i < chan->num_coded_vals; i++) {
                diff = ref_chan->qu_wordlen[i] - ref_chan->qu_wordlen[i - 1];
                delta = get_vlc2(gb, vlc_tab->table, vlc_tab->bits, 1);
                chan->qu_wordlen[i] = (chan->qu_wordlen[i - 1] + diff + delta) & 7;
            }
        } else if (chan->num_coded_vals) {
            flag    = get_bits(gb, 1);
            vlc_tab = &wl_vlc_tabs[get_bits(gb, 1)];

            start_val = get_bits(gb, 3);
            unpack_vq_shape(start_val,
                            &atrac3p_wl_shapes[start_val][get_bits(gb, 4)][0],
                            chan->qu_wordlen, chan->num_coded_vals);

            if (!flag) {
                for (i = 0; i < chan->num_coded_vals; i++) {
                    delta = get_vlc2(gb, vlc_tab->table, vlc_tab->bits, 1);
                    chan->qu_wordlen[i] = (chan->qu_wordlen[i] + delta) & 7;
                }
            } else {
                for (i = 0; i < (chan->num_coded_vals & - 2); i += 2)
                    if (!get_bits1(gb)) {
                        chan->qu_wordlen[i]     = (chan->qu_wordlen[i] +
                                                   get_vlc2(gb, vlc_tab->table,
                                                            vlc_tab->bits, 1)) & 7;
                        chan->qu_wordlen[i + 1] = (chan->qu_wordlen[i + 1] +
                                                   get_vlc2(gb, vlc_tab->table,
                                                            vlc_tab->bits, 1)) & 7;
                    }

                if (chan->num_coded_vals & 1)
                    chan->qu_wordlen[i] = (chan->qu_wordlen[i] +
                                           get_vlc2(gb, vlc_tab->table,
                                                    vlc_tab->bits, 1)) & 7;
            }
        }
        break;
    case 3:
        weight_idx = get_bits(gb, 2);
        if ((ret = num_coded_units(gb, chan, ctx, avctx)) < 0)
            return ret;

        if (chan->num_coded_vals) {
            vlc_tab = &wl_vlc_tabs[get_bits(gb, 2)];

            /* first coefficient is coded directly */
            chan->qu_wordlen[0] = get_bits(gb, 3);

            for (i = 1; i < chan->num_coded_vals; i++) {
                delta = get_vlc2(gb, vlc_tab->table, vlc_tab->bits, 1);
                chan->qu_wordlen[i] = (chan->qu_wordlen[i - 1] + delta) & 7;
            }
        }
        break;
    }

    if (chan->fill_mode == 2) {
        for (i = chan->num_coded_vals; i < ctx->num_quant_units; i++)
            chan->qu_wordlen[i] = ch_num ? get_bits1(gb) : 1;
    } else if (chan->fill_mode == 3) {
        pos = ch_num ? chan->num_coded_vals + chan->split_point
                     : ctx->num_quant_units - chan->split_point;
        for (i = chan->num_coded_vals; i < pos; i++)
            chan->qu_wordlen[i] = 1;
    }

    if (weight_idx)
        return add_wordlen_weights(ctx, chan, weight_idx, avctx);

    return 0;
}

/**
 * Decode scale factor indexes for each quant unit of a channel.
 *
 * @param[in]     gb            the GetBit context
 * @param[in,out] ctx           ptr to the channel unit context
 * @param[in]     ch_num        channel to process
 * @param[in]     avctx         ptr to the AVCodecContext
 * @return result code: 0 = OK, otherwise - error code
 */
static int decode_channel_sf_idx(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
                                 int ch_num, AVCodecContext *avctx)
{
    int i, weight_idx = 0, delta, diff, num_long_vals,
        delta_bits, min_val, vlc_sel, start_val;
    VLC *vlc_tab;
    Atrac3pChanParams *chan     = &ctx->channels[ch_num];
    Atrac3pChanParams *ref_chan = &ctx->channels[0];

    switch (get_bits(gb, 2)) { /* switch according to coding mode */
    case 0: /* coded using constant number of bits */
        for (i = 0; i < ctx->used_quant_units; i++)
            chan->qu_sf_idx[i] = get_bits(gb, 6);
        break;
    case 1:
        if (ch_num) {
            vlc_tab = &sf_vlc_tabs[get_bits(gb, 2)];

            for (i = 0; i < ctx->used_quant_units; i++) {
                delta = get_vlc2(gb, vlc_tab->table, vlc_tab->bits, 1);
                chan->qu_sf_idx[i] = (ref_chan->qu_sf_idx[i] + delta) & 0x3F;
            }
        } else {
            weight_idx = get_bits(gb, 2);
            if (weight_idx == 3) {
                UNPACK_SF_VQ_SHAPE(gb, chan->qu_sf_idx, ctx->used_quant_units);

                num_long_vals = get_bits(gb, 5);
                delta_bits    = get_bits(gb, 2);
                min_val       = get_bits(gb, 4) - 7;

                for (i = 0; i < num_long_vals; i++)
                    chan->qu_sf_idx[i] = (chan->qu_sf_idx[i] +
                                          get_bits(gb, 4) - 7) & 0x3F;

                /* all others are: min_val + delta */
                for (i = num_long_vals; i < ctx->used_quant_units; i++)
                    chan->qu_sf_idx[i] = (chan->qu_sf_idx[i] + min_val +
                                          get_bitsz(gb, delta_bits)) & 0x3F;
            } else {
                num_long_vals = get_bits(gb, 5);
                delta_bits    = get_bits(gb, 3);
                min_val       = get_bits(gb, 6);
                if (num_long_vals > ctx->used_quant_units || delta_bits == 7) {
                    av_log(avctx, AV_LOG_ERROR,
                           "SF mode 1: invalid parameters!\n");
                    return AVERROR_INVALIDDATA;
                }

                /* read full-precision SF indexes */
                for (i = 0; i < num_long_vals; i++)
                    chan->qu_sf_idx[i] = get_bits(gb, 6);

                /* all others are: min_val + delta */
                for (i = num_long_vals; i < ctx->used_quant_units; i++)
                    chan->qu_sf_idx[i] = (min_val +
                                          get_bitsz(gb, delta_bits)) & 0x3F;
            }
        }
        break;
    case 2:
        if (ch_num) {
            vlc_tab = &sf_vlc_tabs[get_bits(gb, 2)];

            delta = get_vlc2(gb, vlc_tab->table, vlc_tab->bits, 1);
            chan->qu_sf_idx[0] = (ref_chan->qu_sf_idx[0] + delta) & 0x3F;

            for (i = 1; i < ctx->used_quant_units; i++) {
                diff  = ref_chan->qu_sf_idx[i] - ref_chan->qu_sf_idx[i - 1];
                delta = get_vlc2(gb, vlc_tab->table, vlc_tab->bits, 1);
                chan->qu_sf_idx[i] = (chan->qu_sf_idx[i - 1] + diff + delta) & 0x3F;
            }
        } else {
            vlc_tab = &sf_vlc_tabs[get_bits(gb, 2) + 4];

            UNPACK_SF_VQ_SHAPE(gb, chan->qu_sf_idx, ctx->used_quant_units);

            for (i = 0; i < ctx->used_quant_units; i++) {
                delta = get_vlc2(gb, vlc_tab->table, vlc_tab->bits, 1);
                chan->qu_sf_idx[i] = (chan->qu_sf_idx[i] +
                                      sign_extend(delta, 4)) & 0x3F;
            }
        }
        break;
    case 3:
        if (ch_num) {
            /* copy coefficients from reference channel */
            for (i = 0; i < ctx->used_quant_units; i++)
                chan->qu_sf_idx[i] = ref_chan->qu_sf_idx[i];
        } else {
            weight_idx = get_bits(gb, 2);
            vlc_sel    = get_bits(gb, 2);
            vlc_tab    = &sf_vlc_tabs[vlc_sel];

            if (weight_idx == 3) {
                vlc_tab = &sf_vlc_tabs[vlc_sel + 4];

                UNPACK_SF_VQ_SHAPE(gb, chan->qu_sf_idx, ctx->used_quant_units);

                diff               = (get_bits(gb, 4)    + 56)   & 0x3F;
                chan->qu_sf_idx[0] = (chan->qu_sf_idx[0] + diff) & 0x3F;

                for (i = 1; i < ctx->used_quant_units; i++) {
                    delta = get_vlc2(gb, vlc_tab->table, vlc_tab->bits, 1);
                    diff               = (diff + sign_extend(delta, 4)) & 0x3F;
                    chan->qu_sf_idx[i] = (diff + chan->qu_sf_idx[i])    & 0x3F;
                }
            } else {
                /* 1st coefficient is coded directly */
                chan->qu_sf_idx[0] = get_bits(gb, 6);

                for (i = 1; i < ctx->used_quant_units; i++) {
                    delta = get_vlc2(gb, vlc_tab->table, vlc_tab->bits, 1);
                    chan->qu_sf_idx[i] = (chan->qu_sf_idx[i - 1] + delta) & 0x3F;
                }
            }
        }
        break;
    }

    if (weight_idx && weight_idx < 3)
        return subtract_sf_weights(ctx, chan, weight_idx, avctx);

    return 0;
}

/**
 * Decode word length information for each channel.
 *
 * @param[in]     gb            the GetBit context
 * @param[in,out] ctx           ptr to the channel unit context
 * @param[in]     num_channels  number of channels to process
 * @param[in]     avctx         ptr to the AVCodecContext
 * @return result code: 0 = OK, otherwise - error code
 */
static int decode_quant_wordlen(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
                                int num_channels, AVCodecContext *avctx)
{
    int ch_num, i, ret;

    for (ch_num = 0; ch_num < num_channels; ch_num++) {
        memset(ctx->channels[ch_num].qu_wordlen, 0,
               sizeof(ctx->channels[ch_num].qu_wordlen));

        if ((ret = decode_channel_wordlen(gb, ctx, ch_num, avctx)) < 0)
            return ret;
    }

    /* scan for last non-zero coeff in both channels and
     * set number of quant units having coded spectrum */
    for (i = ctx->num_quant_units - 1; i >= 0; i--)
        if (ctx->channels[0].qu_wordlen[i] ||
            (num_channels == 2 && ctx->channels[1].qu_wordlen[i]))
            break;
    ctx->used_quant_units = i + 1;

    return 0;
}

/**
 * Decode scale factor indexes for each channel.
 *
 * @param[in]     gb            the GetBit context
 * @param[in,out] ctx           ptr to the channel unit context
 * @param[in]     num_channels  number of channels to process
 * @param[in]     avctx         ptr to the AVCodecContext
 * @return result code: 0 = OK, otherwise - error code
 */
static int decode_scale_factors(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
                                int num_channels, AVCodecContext *avctx)
{
    int ch_num, ret;

    if (!ctx->used_quant_units)
        return 0;

    for (ch_num = 0; ch_num < num_channels; ch_num++) {
        memset(ctx->channels[ch_num].qu_sf_idx, 0,
               sizeof(ctx->channels[ch_num].qu_sf_idx));

        if ((ret = decode_channel_sf_idx(gb, ctx, ch_num, avctx)) < 0)
            return ret;
    }

    return 0;
}

/**
 * Decode number of code table values.
 *
 * @param[in]     gb            the GetBit context
 * @param[in,out] ctx           ptr to the channel unit context
 * @param[in]     avctx         ptr to the AVCodecContext
 * @return result code: 0 = OK, otherwise - error code
 */
static int get_num_ct_values(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
                             AVCodecContext *avctx)
{
    int num_coded_vals;

    if (get_bits1(gb)) {
        num_coded_vals = get_bits(gb, 5);
        if (num_coded_vals > ctx->used_quant_units) {
            av_log(avctx, AV_LOG_ERROR,
                   "Invalid number of code table indexes: %d!\n", num_coded_vals);
            return AVERROR_INVALIDDATA;
        }
        return num_coded_vals;
    } else
        return ctx->used_quant_units;
}

#define DEC_CT_IDX_COMMON(OP)                                           \
    num_vals = get_num_ct_values(gb, ctx, avctx);                       \
    if (num_vals < 0)                                                   \
        return num_vals;                                                \
                                                                        \
    for (i = 0; i < num_vals; i++) {                                    \
        if (chan->qu_wordlen[i]) {                                      \
            chan->qu_tab_idx[i] = OP;                                   \
        } else if (ch_num && ref_chan->qu_wordlen[i])                   \
            /* get clone master flag */                                 \
            chan->qu_tab_idx[i] = get_bits1(gb);                        \
    }

#define CODING_DIRECT get_bits(gb, num_bits)

#define CODING_VLC get_vlc2(gb, vlc_tab->table, vlc_tab->bits, 1)

#define CODING_VLC_DELTA                                                \
    (!i) ? CODING_VLC                                                   \
         : (pred + get_vlc2(gb, delta_vlc->table,                       \
                            delta_vlc->bits, 1)) & mask;                \
    pred = chan->qu_tab_idx[i]

#define CODING_VLC_DIFF                                                 \
    (ref_chan->qu_tab_idx[i] +                                          \
     get_vlc2(gb, vlc_tab->table, vlc_tab->bits, 1)) & mask

/**
 * Decode code table indexes for each quant unit of a channel.
 *
 * @param[in]     gb            the GetBit context
 * @param[in,out] ctx           ptr to the channel unit context
 * @param[in]     ch_num        channel to process
 * @param[in]     avctx         ptr to the AVCodecContext
 * @return result code: 0 = OK, otherwise - error code
 */
static int decode_channel_code_tab(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
                                   int ch_num, AVCodecContext *avctx)
{
    int i, num_vals, num_bits, pred;
    int mask = ctx->use_full_table ? 7 : 3; /* mask for modular arithmetic */
    VLC *vlc_tab, *delta_vlc;
    Atrac3pChanParams *chan     = &ctx->channels[ch_num];
    Atrac3pChanParams *ref_chan = &ctx->channels[0];

    chan->table_type = get_bits1(gb);

    switch (get_bits(gb, 2)) { /* switch according to coding mode */
    case 0: /* directly coded */
        num_bits = ctx->use_full_table + 2;
        DEC_CT_IDX_COMMON(CODING_DIRECT);
        break;
    case 1: /* entropy-coded */
        vlc_tab = ctx->use_full_table ? &ct_vlc_tabs[1]
                                      : ct_vlc_tabs;
        DEC_CT_IDX_COMMON(CODING_VLC);
        break;
    case 2: /* entropy-coded delta */
        if (ctx->use_full_table) {
            vlc_tab   = &ct_vlc_tabs[1];
            delta_vlc = &ct_vlc_tabs[2];
        } else {
            vlc_tab   = ct_vlc_tabs;
            delta_vlc = ct_vlc_tabs;
        }
        pred = 0;
        DEC_CT_IDX_COMMON(CODING_VLC_DELTA);
        break;
    case 3: /* entropy-coded difference to master */
        if (ch_num) {
            vlc_tab = ctx->use_full_table ? &ct_vlc_tabs[3]
                                          : ct_vlc_tabs;
            DEC_CT_IDX_COMMON(CODING_VLC_DIFF);
        }
        break;
    }

    return 0;
}

/**
 * Decode code table indexes for each channel.
 *
 * @param[in]     gb            the GetBit context
 * @param[in,out] ctx           ptr to the channel unit context
 * @param[in]     num_channels  number of channels to process
 * @param[in]     avctx         ptr to the AVCodecContext
 * @return result code: 0 = OK, otherwise - error code
 */
static int decode_code_table_indexes(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
                                     int num_channels, AVCodecContext *avctx)
{
    int ch_num, ret;

    if (!ctx->used_quant_units)
        return 0;

    ctx->use_full_table = get_bits1(gb);

    for (ch_num = 0; ch_num < num_channels; ch_num++) {
        memset(ctx->channels[ch_num].qu_tab_idx, 0,
               sizeof(ctx->channels[ch_num].qu_tab_idx));

        if ((ret = decode_channel_code_tab(gb, ctx, ch_num, avctx)) < 0)
            return ret;
    }

    return 0;
}

/**
 * Decode huffman-coded spectral lines for a given quant unit.
 *
 * This is a generalized version for all known coding modes.
 * Its speed can be improved by creating separate functions for each mode.
 *
 * @param[in]   gb          the GetBit context
 * @param[in]   tab         code table telling how to decode spectral lines
 * @param[in]   vlc_tab     ptr to the huffman table associated with the code table
 * @param[out]  out         pointer to buffer where decoded data should be stored
 * @param[in]   num_specs   number of spectral lines to decode
 */
static void decode_qu_spectra(GetBitContext *gb, const Atrac3pSpecCodeTab *tab,
                              VLC *vlc_tab, int16_t *out, const int num_specs)
{
    int i, j, pos, cf;
    int group_size = tab->group_size;
    int num_coeffs = tab->num_coeffs;
    int bits       = tab->bits;
    int is_signed  = tab->is_signed;
    unsigned val;

    for (pos = 0; pos < num_specs;) {
        if (group_size == 1 || get_bits1(gb)) {
            for (j = 0; j < group_size; j++) {
                val = get_vlc2(gb, vlc_tab->table, vlc_tab->bits, 1);

                for (i = 0; i < num_coeffs; i++) {
                    cf = av_mod_uintp2(val, bits);
                    if (is_signed)
                        cf = sign_extend(cf, bits);
                    else if (cf && get_bits1(gb))
                        cf = -cf;

                    out[pos++] = cf;
                    val      >>= bits;
                }
            }
        } else /* group skipped */
            pos += group_size * num_coeffs;
    }
}

/**
 * Decode huffman-coded IMDCT spectrum for all channels.
 *
 * @param[in]     gb            the GetBit context
 * @param[in,out] ctx           ptr to the channel unit context
 * @param[in]     num_channels  number of channels to process
 * @param[in]     avctx         ptr to the AVCodecContext
 */
static void decode_spectrum(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
                            int num_channels, AVCodecContext *avctx)
{
    int i, ch_num, qu, wordlen, codetab, tab_index, num_specs;
    const Atrac3pSpecCodeTab *tab;
    Atrac3pChanParams *chan;

    for (ch_num = 0; ch_num < num_channels; ch_num++) {
        chan = &ctx->channels[ch_num];

        memset(chan->spectrum, 0, sizeof(chan->spectrum));

        /* set power compensation level to disabled */
        memset(chan->power_levs, ATRAC3P_POWER_COMP_OFF, sizeof(chan->power_levs));

        for (qu = 0; qu < ctx->used_quant_units; qu++) {
            num_specs = ff_atrac3p_qu_to_spec_pos[qu + 1] -
                        ff_atrac3p_qu_to_spec_pos[qu];

            wordlen = chan->qu_wordlen[qu];
            codetab = chan->qu_tab_idx[qu];
            if (wordlen) {
                if (!ctx->use_full_table)
                    codetab = atrac3p_ct_restricted_to_full[chan->table_type][wordlen - 1][codetab];

                tab_index = (chan->table_type * 8 + codetab) * 7 + wordlen - 1;
                tab       = &atrac3p_spectra_tabs[tab_index];

                /* this allows reusing VLC tables */
                if (tab->redirect >= 0)
                    tab_index = tab->redirect;

                decode_qu_spectra(gb, tab, &spec_vlc_tabs[tab_index],
                                  &chan->spectrum[ff_atrac3p_qu_to_spec_pos[qu]],
                                  num_specs);
            } else if (ch_num && ctx->channels[0].qu_wordlen[qu] && !codetab) {
                /* copy coefficients from master */
                memcpy(&chan->spectrum[ff_atrac3p_qu_to_spec_pos[qu]],
                       &ctx->channels[0].spectrum[ff_atrac3p_qu_to_spec_pos[qu]],
                       num_specs *
                       sizeof(chan->spectrum[ff_atrac3p_qu_to_spec_pos[qu]]));
                chan->qu_wordlen[qu] = ctx->channels[0].qu_wordlen[qu];
            }
        }

        /* Power compensation levels only present in the bitstream
         * if there are more than 2 quant units. The lowest two units
         * correspond to the frequencies 0...351 Hz, whose shouldn't
         * be affected by the power compensation. */
        if (ctx->used_quant_units > 2) {
            num_specs = atrac3p_subband_to_num_powgrps[ctx->num_coded_subbands - 1];
            for (i = 0; i < num_specs; i++)
                chan->power_levs[i] = get_bits(gb, 4);
        }
    }
}

/**
 * Retrieve specified amount of flag bits from the input bitstream.
 * The data can be shortened in the case of the following two common conditions:
 * if all bits are zero then only one signal bit = 0 will be stored,
 * if all bits are ones then two signal bits = 1,0 will be stored.
 * Otherwise, all necessary bits will be directly stored
 * prefixed by two signal bits = 1,1.
 *
 * @param[in]   gb              ptr to the GetBitContext
 * @param[out]  out             where to place decoded flags
 * @param[in]   num_flags       number of flags to process
 * @return: 0 = all flag bits are zero, 1 = there is at least one non-zero flag bit
 */
static int get_subband_flags(GetBitContext *gb, uint8_t *out, int num_flags)
{
    int i, result;

    memset(out, 0, num_flags);

    result = get_bits1(gb);
    if (result) {
        if (get_bits1(gb))
            for (i = 0; i < num_flags; i++)
                out[i] = get_bits1(gb);
        else
            memset(out, 1, num_flags);
    }

    return result;
}

/**
 * Decode mdct window shape flags for all channels.
 *
 * @param[in]     gb            the GetBit context
 * @param[in,out] ctx           ptr to the channel unit context
 * @param[in]     num_channels  number of channels to process
 */
static void decode_window_shape(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
                                int num_channels)
{
    int ch_num;

    for (ch_num = 0; ch_num < num_channels; ch_num++)
        get_subband_flags(gb, ctx->channels[ch_num].wnd_shape,
                          ctx->num_subbands);
}

/**
 * Decode number of gain control points.
 *
 * @param[in]     gb              the GetBit context
 * @param[in,out] ctx             ptr to the channel unit context
 * @param[in]     ch_num          channel to process
 * @param[in]     coded_subbands  number of subbands to process
 * @return result code: 0 = OK, otherwise - error code
 */
static int decode_gainc_npoints(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
                                int ch_num, int coded_subbands)
{
    int i, delta, delta_bits, min_val;
    Atrac3pChanParams *chan     = &ctx->channels[ch_num];
    Atrac3pChanParams *ref_chan = &ctx->channels[0];

    switch (get_bits(gb, 2)) { /* switch according to coding mode */
    case 0: /* fixed-length coding */
        for (i = 0; i < coded_subbands; i++)
            chan->gain_data[i].num_points = get_bits(gb, 3);
        break;
    case 1: /* variable-length coding */
        for (i = 0; i < coded_subbands; i++)
            chan->gain_data[i].num_points =
                get_vlc2(gb, gain_vlc_tabs[0].table,
                         gain_vlc_tabs[0].bits, 1);
        break;
    case 2:
        if (ch_num) { /* VLC modulo delta to master channel */
            for (i = 0; i < coded_subbands; i++) {
                delta = get_vlc2(gb, gain_vlc_tabs[1].table,
                                 gain_vlc_tabs[1].bits, 1);
                chan->gain_data[i].num_points =
                    (ref_chan->gain_data[i].num_points + delta) & 7;
            }
        } else { /* VLC modulo delta to previous */
            chan->gain_data[0].num_points =
                get_vlc2(gb, gain_vlc_tabs[0].table,
                         gain_vlc_tabs[0].bits, 1);

            for (i = 1; i < coded_subbands; i++) {
                delta = get_vlc2(gb, gain_vlc_tabs[1].table,
                                 gain_vlc_tabs[1].bits, 1);
                chan->gain_data[i].num_points =
                    (chan->gain_data[i - 1].num_points + delta) & 7;
            }
        }
        break;
    case 3:
        if (ch_num) { /* copy data from master channel */
            for (i = 0; i < coded_subbands; i++)
                chan->gain_data[i].num_points =
                    ref_chan->gain_data[i].num_points;
        } else { /* shorter delta to min */
            delta_bits = get_bits(gb, 2);
            min_val    = get_bits(gb, 3);

            for (i = 0; i < coded_subbands; i++) {
                chan->gain_data[i].num_points = min_val + get_bitsz(gb, delta_bits);
                if (chan->gain_data[i].num_points > 7)
                    return AVERROR_INVALIDDATA;
            }
        }
    }

    return 0;
}

/**
 * Implements coding mode 3 (slave) for gain compensation levels.
 *
 * @param[out]   dst   ptr to the output array
 * @param[in]    ref   ptr to the reference channel
 */
static inline void gainc_level_mode3s(AtracGainInfo *dst, AtracGainInfo *ref)
{
    int i;

    for (i = 0; i < dst->num_points; i++)
        dst->lev_code[i] = (i >= ref->num_points) ? 7 : ref->lev_code[i];
}

/**
 * Implements coding mode 1 (master) for gain compensation levels.
 *
 * @param[in]     gb     the GetBit context
 * @param[in]     ctx    ptr to the channel unit context
 * @param[out]    dst    ptr to the output array
 */
static inline void gainc_level_mode1m(GetBitContext *gb,
                                      Atrac3pChanUnitCtx *ctx,
                                      AtracGainInfo *dst)
{
    int i, delta;

    if (dst->num_points > 0)
        dst->lev_code[0] = get_vlc2(gb, gain_vlc_tabs[2].table,
                                    gain_vlc_tabs[2].bits, 1);

    for (i = 1; i < dst->num_points; i++) {
        delta = get_vlc2(gb, gain_vlc_tabs[3].table,
                         gain_vlc_tabs[3].bits, 1);
        dst->lev_code[i] = (dst->lev_code[i - 1] + delta) & 0xF;
    }
}

/**
 * Decode level code for each gain control point.
 *
 * @param[in]     gb              the GetBit context
 * @param[in,out] ctx             ptr to the channel unit context
 * @param[in]     ch_num          channel to process
 * @param[in]     coded_subbands  number of subbands to process
 * @return result code: 0 = OK, otherwise - error code
 */
static int decode_gainc_levels(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
                               int ch_num, int coded_subbands)
{
    int sb, i, delta, delta_bits, min_val, pred;
    Atrac3pChanParams *chan     = &ctx->channels[ch_num];
    Atrac3pChanParams *ref_chan = &ctx->channels[0];

    switch (get_bits(gb, 2)) { /* switch according to coding mode */
    case 0: /* fixed-length coding */
        for (sb = 0; sb < coded_subbands; sb++)
            for (i = 0; i < chan->gain_data[sb].num_points; i++)
                chan->gain_data[sb].lev_code[i] = get_bits(gb, 4);
        break;
    case 1:
        if (ch_num) { /* VLC modulo delta to master channel */
            for (sb = 0; sb < coded_subbands; sb++)
                for (i = 0; i < chan->gain_data[sb].num_points; i++) {
                    delta = get_vlc2(gb, gain_vlc_tabs[5].table,
                                     gain_vlc_tabs[5].bits, 1);
                    pred = (i >= ref_chan->gain_data[sb].num_points)
                           ? 7 : ref_chan->gain_data[sb].lev_code[i];
                    chan->gain_data[sb].lev_code[i] = (pred + delta) & 0xF;
                }
        } else { /* VLC modulo delta to previous */
            for (sb = 0; sb < coded_subbands; sb++)
                gainc_level_mode1m(gb, ctx, &chan->gain_data[sb]);
        }
        break;
    case 2:
        if (ch_num) { /* VLC modulo delta to previous or clone master */
            for (sb = 0; sb < coded_subbands; sb++)
                if (chan->gain_data[sb].num_points > 0) {
                    if (get_bits1(gb))
                        gainc_level_mode1m(gb, ctx, &chan->gain_data[sb]);
                    else
                        gainc_level_mode3s(&chan->gain_data[sb],
                                           &ref_chan->gain_data[sb]);
                }
        } else { /* VLC modulo delta to lev_codes of previous subband */
            if (chan->gain_data[0].num_points > 0)
                gainc_level_mode1m(gb, ctx, &chan->gain_data[0]);

            for (sb = 1; sb < coded_subbands; sb++)
                for (i = 0; i < chan->gain_data[sb].num_points; i++) {
                    delta = get_vlc2(gb, gain_vlc_tabs[4].table,
                                     gain_vlc_tabs[4].bits, 1);
                    pred = (i >= chan->gain_data[sb - 1].num_points)
                           ? 7 : chan->gain_data[sb - 1].lev_code[i];
                    chan->gain_data[sb].lev_code[i] = (pred + delta) & 0xF;
                }
        }
        break;
    case 3:
        if (ch_num) { /* clone master */
            for (sb = 0; sb < coded_subbands; sb++)
                gainc_level_mode3s(&chan->gain_data[sb],
                                   &ref_chan->gain_data[sb]);
        } else { /* shorter delta to min */
            delta_bits = get_bits(gb, 2);
            min_val    = get_bits(gb, 4);

            for (sb = 0; sb < coded_subbands; sb++)
                for (i = 0; i < chan->gain_data[sb].num_points; i++) {
                    chan->gain_data[sb].lev_code[i] = min_val + get_bitsz(gb, delta_bits);
                    if (chan->gain_data[sb].lev_code[i] > 15)
                        return AVERROR_INVALIDDATA;
                }
        }
        break;
    }

    return 0;
}

/**
 * Implements coding mode 0 for gain compensation locations.
 *
 * @param[in]     gb     the GetBit context
 * @param[in]     ctx    ptr to the channel unit context
 * @param[out]    dst    ptr to the output array
 * @param[in]     pos    position of the value to be processed
 */
static inline void gainc_loc_mode0(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
                                   AtracGainInfo *dst, int pos)
{
    int delta_bits;

    if (!pos || dst->loc_code[pos - 1] < 15)
        dst->loc_code[pos] = get_bits(gb, 5);
    else if (dst->loc_code[pos - 1] >= 30)
        dst->loc_code[pos] = 31;
    else {
        delta_bits         = av_log2(30 - dst->loc_code[pos - 1]) + 1;
        dst->loc_code[pos] = dst->loc_code[pos - 1] +
                             get_bits(gb, delta_bits) + 1;
    }
}

/**
 * Implements coding mode 1 for gain compensation locations.
 *
 * @param[in]     gb     the GetBit context
 * @param[in]     ctx    ptr to the channel unit context
 * @param[out]    dst    ptr to the output array
 */
static inline void gainc_loc_mode1(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
                                   AtracGainInfo *dst)
{
    int i;
    VLC *tab;

    if (dst->num_points > 0) {
        /* 1st coefficient is stored directly */
        dst->loc_code[0] = get_bits(gb, 5);

        for (i = 1; i < dst->num_points; i++) {
            /* switch VLC according to the curve direction
             * (ascending/descending) */
            tab              = (dst->lev_code[i] <= dst->lev_code[i - 1])
                               ? &gain_vlc_tabs[7]
                               : &gain_vlc_tabs[9];
            dst->loc_code[i] = dst->loc_code[i - 1] +
                               get_vlc2(gb, tab->table, tab->bits, 1);
        }
    }
}

/**
 * Decode location code for each gain control point.
 *
 * @param[in]     gb              the GetBit context
 * @param[in,out] ctx             ptr to the channel unit context
 * @param[in]     ch_num          channel to process
 * @param[in]     coded_subbands  number of subbands to process
 * @param[in]     avctx           ptr to the AVCodecContext
 * @return result code: 0 = OK, otherwise - error code
 */
static int decode_gainc_loc_codes(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
                                  int ch_num, int coded_subbands,
                                  AVCodecContext *avctx)
{
    int sb, i, delta, delta_bits, min_val, pred, more_than_ref;
    AtracGainInfo *dst, *ref;
    VLC *tab;
    Atrac3pChanParams *chan     = &ctx->channels[ch_num];
    Atrac3pChanParams *ref_chan = &ctx->channels[0];

    switch (get_bits(gb, 2)) { /* switch according to coding mode */
    case 0: /* sequence of numbers in ascending order */
        for (sb = 0; sb < coded_subbands; sb++)
            for (i = 0; i < chan->gain_data[sb].num_points; i++)
                gainc_loc_mode0(gb, ctx, &chan->gain_data[sb], i);
        break;
    case 1:
        if (ch_num) {
            for (sb = 0; sb < coded_subbands; sb++) {
                if (chan->gain_data[sb].num_points <= 0)
                    continue;
                dst = &chan->gain_data[sb];
                ref = &ref_chan->gain_data[sb];

                /* 1st value is vlc-coded modulo delta to master */
                delta = get_vlc2(gb, gain_vlc_tabs[10].table,
                                 gain_vlc_tabs[10].bits, 1);
                pred = ref->num_points > 0 ? ref->loc_code[0] : 0;
                dst->loc_code[0] = (pred + delta) & 0x1F;

                for (i = 1; i < dst->num_points; i++) {
                    more_than_ref = i >= ref->num_points;
                    if (dst->lev_code[i] > dst->lev_code[i - 1]) {
                        /* ascending curve */
                        if (more_than_ref) {
                            delta =
                                get_vlc2(gb, gain_vlc_tabs[9].table,
                                         gain_vlc_tabs[9].bits, 1);
                            dst->loc_code[i] = dst->loc_code[i - 1] + delta;
                        } else {
                            if (get_bits1(gb))
                                gainc_loc_mode0(gb, ctx, dst, i);  // direct coding
                            else
                                dst->loc_code[i] = ref->loc_code[i];  // clone master
                        }
                    } else { /* descending curve */
                        tab   = more_than_ref ? &gain_vlc_tabs[7]
                                              : &gain_vlc_tabs[10];
                        delta = get_vlc2(gb, tab->table, tab->bits, 1);
                        if (more_than_ref)
                            dst->loc_code[i] = dst->loc_code[i - 1] + delta;
                        else
                            dst->loc_code[i] = (ref->loc_code[i] + delta) & 0x1F;
                    }
                }
            }
        } else /* VLC delta to previous */
            for (sb = 0; sb < coded_subbands; sb++)
                gainc_loc_mode1(gb, ctx, &chan->gain_data[sb]);
        break;
    case 2:
        if (ch_num) {
            for (sb = 0; sb < coded_subbands; sb++) {
                if (chan->gain_data[sb].num_points <= 0)
                    continue;
                dst = &chan->gain_data[sb];
                ref = &ref_chan->gain_data[sb];
                if (dst->num_points > ref->num_points || get_bits1(gb))
                    gainc_loc_mode1(gb, ctx, dst);
                else /* clone master for the whole subband */
                    for (i = 0; i < chan->gain_data[sb].num_points; i++)
                        dst->loc_code[i] = ref->loc_code[i];
            }
        } else {
            /* data for the first subband is coded directly */
            for (i = 0; i < chan->gain_data[0].num_points; i++)
                gainc_loc_mode0(gb, ctx, &chan->gain_data[0], i);

            for (sb = 1; sb < coded_subbands; sb++) {
                if (chan->gain_data[sb].num_points <= 0)
                    continue;
                dst = &chan->gain_data[sb];

                /* 1st value is vlc-coded modulo delta to the corresponding
                 * value of the previous subband if any or zero */
                delta = get_vlc2(gb, gain_vlc_tabs[6].table,
                                 gain_vlc_tabs[6].bits, 1);
                pred             = dst[-1].num_points > 0
                                   ? dst[-1].loc_code[0] : 0;
                dst->loc_code[0] = (pred + delta) & 0x1F;

                for (i = 1; i < dst->num_points; i++) {
                    more_than_ref = i >= dst[-1].num_points;
                    /* Select VLC table according to curve direction and
                     * presence of prediction. */
                    tab = &gain_vlc_tabs[(dst->lev_code[i] > dst->lev_code[i - 1]) *
                                                   2 + more_than_ref + 6];
                    delta = get_vlc2(gb, tab->table, tab->bits, 1);
                    if (more_than_ref)
                        dst->loc_code[i] = dst->loc_code[i - 1] + delta;
                    else
                        dst->loc_code[i] = (dst[-1].loc_code[i] + delta) & 0x1F;
                }
            }
        }
        break;
    case 3:
        if (ch_num) { /* clone master or direct or direct coding */
            for (sb = 0; sb < coded_subbands; sb++)
                for (i = 0; i < chan->gain_data[sb].num_points; i++) {
                    if (i >= ref_chan->gain_data[sb].num_points)
                        gainc_loc_mode0(gb, ctx, &chan->gain_data[sb], i);
                    else
                        chan->gain_data[sb].loc_code[i] =
                            ref_chan->gain_data[sb].loc_code[i];
                }
        } else { /* shorter delta to min */
            delta_bits = get_bits(gb, 2) + 1;
            min_val    = get_bits(gb, 5);

            for (sb = 0; sb < coded_subbands; sb++)
                for (i = 0; i < chan->gain_data[sb].num_points; i++)
                    chan->gain_data[sb].loc_code[i] = min_val + i +
                                                      get_bits(gb, delta_bits);
        }
        break;
    }

    /* Validate decoded information */
    for (sb = 0; sb < coded_subbands; sb++) {
        dst = &chan->gain_data[sb];
        for (i = 0; i < chan->gain_data[sb].num_points; i++) {
            if (dst->loc_code[i] < 0 || dst->loc_code[i] > 31 ||
                (i && dst->loc_code[i] <= dst->loc_code[i - 1])) {
                av_log(avctx, AV_LOG_ERROR,
                       "Invalid gain location: ch=%d, sb=%d, pos=%d, val=%d\n",
                       ch_num, sb, i, dst->loc_code[i]);
                return AVERROR_INVALIDDATA;
            }
        }
    }

    return 0;
}

/**
 * Decode gain control data for all channels.
 *
 * @param[in]     gb            the GetBit context
 * @param[in,out] ctx           ptr to the channel unit context
 * @param[in]     num_channels  number of channels to process
 * @param[in]     avctx         ptr to the AVCodecContext
 * @return result code: 0 = OK, otherwise - error code
 */
static int decode_gainc_data(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
                             int num_channels, AVCodecContext *avctx)
{
    int ch_num, coded_subbands, sb, ret;

    for (ch_num = 0; ch_num < num_channels; ch_num++) {
        memset(ctx->channels[ch_num].gain_data, 0,
               sizeof(*ctx->channels[ch_num].gain_data) * ATRAC3P_SUBBANDS);

        if (get_bits1(gb)) { /* gain control data present? */
            coded_subbands = get_bits(gb, 4) + 1;
            if (get_bits1(gb)) /* is high band gain data replication on? */
                ctx->channels[ch_num].num_gain_subbands = get_bits(gb, 4) + 1;
            else
                ctx->channels[ch_num].num_gain_subbands = coded_subbands;

            if ((ret = decode_gainc_npoints(gb, ctx, ch_num, coded_subbands)) < 0 ||
                (ret = decode_gainc_levels(gb, ctx, ch_num, coded_subbands))  < 0 ||
                (ret = decode_gainc_loc_codes(gb, ctx, ch_num, coded_subbands, avctx)) < 0)
                return ret;

            if (coded_subbands > 0) { /* propagate gain data if requested */
                for (sb = coded_subbands; sb < ctx->channels[ch_num].num_gain_subbands; sb++)
                    ctx->channels[ch_num].gain_data[sb] =
                        ctx->channels[ch_num].gain_data[sb - 1];
            }
        } else {
            ctx->channels[ch_num].num_gain_subbands = 0;
        }
    }

    return 0;
}

/**
 * Decode envelope for all tones of a channel.
 *
 * @param[in]     gb                the GetBit context
 * @param[in,out] ctx               ptr to the channel unit context
 * @param[in]     ch_num            channel to process
 * @param[in]     band_has_tones    ptr to an array of per-band-flags:
 *                                  1 - tone data present
 */
static void decode_tones_envelope(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
                                  int ch_num, int band_has_tones[])
{
    int sb;
    Atrac3pWavesData *dst = ctx->channels[ch_num].tones_info;
    Atrac3pWavesData *ref = ctx->channels[0].tones_info;

    if (!ch_num || !get_bits1(gb)) { /* mode 0: fixed-length coding */
        for (sb = 0; sb < ctx->waves_info->num_tone_bands; sb++) {
            if (!band_has_tones[sb])
                continue;
            dst[sb].pend_env.has_start_point = get_bits1(gb);
            dst[sb].pend_env.start_pos       = dst[sb].pend_env.has_start_point
                                               ? get_bits(gb, 5) : -1;
            dst[sb].pend_env.has_stop_point  = get_bits1(gb);
            dst[sb].pend_env.stop_pos        = dst[sb].pend_env.has_stop_point
                                               ? get_bits(gb, 5) : 32;
        }
    } else { /* mode 1(slave only): copy master */
        for (sb = 0; sb < ctx->waves_info->num_tone_bands; sb++) {
            if (!band_has_tones[sb])
                continue;
            dst[sb].pend_env.has_start_point = ref[sb].pend_env.has_start_point;
            dst[sb].pend_env.has_stop_point  = ref[sb].pend_env.has_stop_point;
            dst[sb].pend_env.start_pos       = ref[sb].pend_env.start_pos;
            dst[sb].pend_env.stop_pos        = ref[sb].pend_env.stop_pos;
        }
    }
}

/**
 * Decode number of tones for each subband of a channel.
 *
 * @param[in]     gb                the GetBit context
 * @param[in,out] ctx               ptr to the channel unit context
 * @param[in]     ch_num            channel to process
 * @param[in]     band_has_tones    ptr to an array of per-band-flags:
 *                                  1 - tone data present
 * @param[in]     avctx             ptr to the AVCodecContext
 * @return result code: 0 = OK, otherwise - error code
 */
static int decode_band_numwavs(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
                               int ch_num, int band_has_tones[],
                               AVCodecContext *avctx)
{
    int mode, sb, delta;
    Atrac3pWavesData *dst = ctx->channels[ch_num].tones_info;
    Atrac3pWavesData *ref = ctx->channels[0].tones_info;

    mode = get_bits(gb, ch_num + 1);
    switch (mode) {
    case 0: /** fixed-length coding */
        for (sb = 0; sb < ctx->waves_info->num_tone_bands; sb++)
            if (band_has_tones[sb])
                dst[sb].num_wavs = get_bits(gb, 4);
        break;
    case 1: /** variable-length coding */
        for (sb = 0; sb < ctx->waves_info->num_tone_bands; sb++)
            if (band_has_tones[sb])
                dst[sb].num_wavs =
                    get_vlc2(gb, tone_vlc_tabs[1].table,
                             tone_vlc_tabs[1].bits, 1);
        break;
    case 2: /** VLC modulo delta to master (slave only) */
        for (sb = 0; sb < ctx->waves_info->num_tone_bands; sb++)
            if (band_has_tones[sb]) {
                delta = get_vlc2(gb, tone_vlc_tabs[2].table,
                                 tone_vlc_tabs[2].bits, 1);
                delta = sign_extend(delta, 3);
                dst[sb].num_wavs = (ref[sb].num_wavs + delta) & 0xF;
            }
        break;
    case 3: /** copy master (slave only) */
        for (sb = 0; sb < ctx->waves_info->num_tone_bands; sb++)
            if (band_has_tones[sb])
                dst[sb].num_wavs = ref[sb].num_wavs;
        break;
    }

    /** initialize start tone index for each subband */
    for (sb = 0; sb < ctx->waves_info->num_tone_bands; sb++)
        if (band_has_tones[sb]) {
            if (ctx->waves_info->tones_index + dst[sb].num_wavs > 48) {
                av_log(avctx, AV_LOG_ERROR,
                       "Too many tones: %d (max. 48), frame: %d!\n",
                       ctx->waves_info->tones_index + dst[sb].num_wavs,
                       avctx->frame_number);
                return AVERROR_INVALIDDATA;
            }
            dst[sb].start_index           = ctx->waves_info->tones_index;
            ctx->waves_info->tones_index += dst[sb].num_wavs;
        }

    return 0;
}

/**
 * Decode frequency information for each subband of a channel.
 *
 * @param[in]     gb                the GetBit context
 * @param[in,out] ctx               ptr to the channel unit context
 * @param[in]     ch_num            channel to process
 * @param[in]     band_has_tones    ptr to an array of per-band-flags:
 *                                  1 - tone data present
 */
static void decode_tones_frequency(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
                                   int ch_num, int band_has_tones[])
{
    int sb, i, direction, nbits, pred, delta;
    Atrac3pWaveParam *iwav, *owav;
    Atrac3pWavesData *dst = ctx->channels[ch_num].tones_info;
    Atrac3pWavesData *ref = ctx->channels[0].tones_info;

    if (!ch_num || !get_bits1(gb)) { /* mode 0: fixed-length coding */
        for (sb = 0; sb < ctx->waves_info->num_tone_bands; sb++) {
            if (!band_has_tones[sb] || !dst[sb].num_wavs)
                continue;
            iwav      = &ctx->waves_info->waves[dst[sb].start_index];
            direction = (dst[sb].num_wavs > 1) ? get_bits1(gb) : 0;
            if (direction) { /** packed numbers in descending order */
                if (dst[sb].num_wavs)
                    iwav[dst[sb].num_wavs - 1].freq_index = get_bits(gb, 10);
                for (i = dst[sb].num_wavs - 2; i >= 0 ; i--) {
                    nbits = av_log2(iwav[i+1].freq_index) + 1;
                    iwav[i].freq_index = get_bits(gb, nbits);
                }
            } else { /** packed numbers in ascending order */
                for (i = 0; i < dst[sb].num_wavs; i++) {
                    if (!i || iwav[i - 1].freq_index < 512)
                        iwav[i].freq_index = get_bits(gb, 10);
                    else {
                        nbits = av_log2(1023 - iwav[i - 1].freq_index) + 1;
                        iwav[i].freq_index = get_bits(gb, nbits) +
                                             1024 - (1 << nbits);
                    }
                }
            }
        }
    } else { /* mode 1: VLC modulo delta to master (slave only) */
        for (sb = 0; sb < ctx->waves_info->num_tone_bands; sb++) {
            if (!band_has_tones[sb] || !dst[sb].num_wavs)
                continue;
            iwav = &ctx->waves_info->waves[ref[sb].start_index];
            owav = &ctx->waves_info->waves[dst[sb].start_index];
            for (i = 0; i < dst[sb].num_wavs; i++) {
                delta = get_vlc2(gb, tone_vlc_tabs[6].table,
                                 tone_vlc_tabs[6].bits, 1);
                delta = sign_extend(delta, 8);
                pred  = (i < ref[sb].num_wavs) ? iwav[i].freq_index :
                        (ref[sb].num_wavs ? iwav[ref[sb].num_wavs - 1].freq_index : 0);
                owav[i].freq_index = (pred + delta) & 0x3FF;
            }
        }
    }
}

/**
 * Decode amplitude information for each subband of a channel.
 *
 * @param[in]     gb                the GetBit context
 * @param[in,out] ctx               ptr to the channel unit context
 * @param[in]     ch_num            channel to process
 * @param[in]     band_has_tones    ptr to an array of per-band-flags:
 *                                  1 - tone data present
 */
static void decode_tones_amplitude(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
                                   int ch_num, int band_has_tones[])
{
    int mode, sb, j, i, diff, maxdiff, fi, delta, pred;
    Atrac3pWaveParam *wsrc, *wref;
    int refwaves[48] = { 0 };
    Atrac3pWavesData *dst = ctx->channels[ch_num].tones_info;
    Atrac3pWavesData *ref = ctx->channels[0].tones_info;

    if (ch_num) {
        for (sb = 0; sb < ctx->waves_info->num_tone_bands; sb++) {
            if (!band_has_tones[sb] || !dst[sb].num_wavs)
                continue;
            wsrc = &ctx->waves_info->waves[dst[sb].start_index];
            wref = &ctx->waves_info->waves[ref[sb].start_index];
            for (j = 0; j < dst[sb].num_wavs; j++) {
                for (i = 0, fi = 0, maxdiff = 1024; i < ref[sb].num_wavs; i++) {
                    diff = FFABS(wsrc[j].freq_index - wref[i].freq_index);
                    if (diff < maxdiff) {
                        maxdiff = diff;
                        fi      = i;
                    }
                }

                if (maxdiff < 8)
                    refwaves[dst[sb].start_index + j] = fi + ref[sb].start_index;
                else if (j < ref[sb].num_wavs)
                    refwaves[dst[sb].start_index + j] = j + ref[sb].start_index;
                else
                    refwaves[dst[sb].start_index + j] = -1;
            }
        }
    }

    mode = get_bits(gb, ch_num + 1);

    switch (mode) {
    case 0: /** fixed-length coding */
        for (sb = 0; sb < ctx->waves_info->num_tone_bands; sb++) {
            if (!band_has_tones[sb] || !dst[sb].num_wavs)
                continue;
            if (ctx->waves_info->amplitude_mode)
                for (i = 0; i < dst[sb].num_wavs; i++)
                    ctx->waves_info->waves[dst[sb].start_index + i].amp_sf = get_bits(gb, 6);
            else
                ctx->waves_info->waves[dst[sb].start_index].amp_sf = get_bits(gb, 6);
        }
        break;
    case 1: /** min + VLC delta */
        for (sb = 0; sb < ctx->waves_info->num_tone_bands; sb++) {
            if (!band_has_tones[sb] || !dst[sb].num_wavs)
                continue;
            if (ctx->waves_info->amplitude_mode)
                for (i = 0; i < dst[sb].num_wavs; i++)
                    ctx->waves_info->waves[dst[sb].start_index + i].amp_sf =
                        get_vlc2(gb, tone_vlc_tabs[3].table,
                                 tone_vlc_tabs[3].bits, 1) + 20;
            else
                ctx->waves_info->waves[dst[sb].start_index].amp_sf =
                    get_vlc2(gb, tone_vlc_tabs[4].table,
                             tone_vlc_tabs[4].bits, 1) + 24;
        }
        break;
    case 2: /** VLC modulo delta to master (slave only) */
        for (sb = 0; sb < ctx->waves_info->num_tone_bands; sb++) {
            if (!band_has_tones[sb] || !dst[sb].num_wavs)
                continue;
            for (i = 0; i < dst[sb].num_wavs; i++) {
                delta = get_vlc2(gb, tone_vlc_tabs[5].table,
                                 tone_vlc_tabs[5].bits, 1);
                delta = sign_extend(delta, 5);
                pred  = refwaves[dst[sb].start_index + i] >= 0 ?
                        ctx->waves_info->waves[refwaves[dst[sb].start_index + i]].amp_sf : 34;
                ctx->waves_info->waves[dst[sb].start_index + i].amp_sf = (pred + delta) & 0x3F;
            }
        }
        break;
    case 3: /** clone master (slave only) */
        for (sb = 0; sb < ctx->waves_info->num_tone_bands; sb++) {
            if (!band_has_tones[sb])
                continue;
            for (i = 0; i < dst[sb].num_wavs; i++)
                ctx->waves_info->waves[dst[sb].start_index + i].amp_sf =
                    refwaves[dst[sb].start_index + i] >= 0
                    ? ctx->waves_info->waves[refwaves[dst[sb].start_index + i]].amp_sf
                    : 32;
        }
        break;
    }
}

/**
 * Decode phase information for each subband of a channel.
 *
 * @param[in]     gb                the GetBit context
 * @param[in,out] ctx               ptr to the channel unit context
 * @param[in]     ch_num            channel to process
 * @param[in]     band_has_tones    ptr to an array of per-band-flags:
 *                                  1 - tone data present
 */
static void decode_tones_phase(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
                               int ch_num, int band_has_tones[])
{
    int sb, i;
    Atrac3pWaveParam *wparam;
    Atrac3pWavesData *dst = ctx->channels[ch_num].tones_info;

    for (sb = 0; sb < ctx->waves_info->num_tone_bands; sb++) {
        if (!band_has_tones[sb])
            continue;
        wparam = &ctx->waves_info->waves[dst[sb].start_index];
        for (i = 0; i < dst[sb].num_wavs; i++)
            wparam[i].phase_index = get_bits(gb, 5);
    }
}

/**
 * Decode tones info for all channels.
 *
 * @param[in]     gb            the GetBit context
 * @param[in,out] ctx           ptr to the channel unit context
 * @param[in]     num_channels  number of channels to process
 * @param[in]     avctx         ptr to the AVCodecContext
 * @return result code: 0 = OK, otherwise - error code
 */
static int decode_tones_info(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
                             int num_channels, AVCodecContext *avctx)
{
    int ch_num, i, ret;
    int band_has_tones[16];

    for (ch_num = 0; ch_num < num_channels; ch_num++)
        memset(ctx->channels[ch_num].tones_info, 0,
               sizeof(*ctx->channels[ch_num].tones_info) * ATRAC3P_SUBBANDS);

    ctx->waves_info->tones_present = get_bits1(gb);
    if (!ctx->waves_info->tones_present)
        return 0;

    memset(ctx->waves_info->waves, 0, sizeof(ctx->waves_info->waves));

    ctx->waves_info->amplitude_mode = get_bits1(gb);
    if (!ctx->waves_info->amplitude_mode) {
        avpriv_report_missing_feature(avctx, "GHA amplitude mode 0");
        return AVERROR_PATCHWELCOME;
    }

    ctx->waves_info->num_tone_bands =
        get_vlc2(gb, tone_vlc_tabs[0].table,
                 tone_vlc_tabs[0].bits, 1) + 1;

    if (num_channels == 2) {
        get_subband_flags(gb, ctx->waves_info->tone_sharing, ctx->waves_info->num_tone_bands);
        get_subband_flags(gb, ctx->waves_info->tone_master,  ctx->waves_info->num_tone_bands);
        get_subband_flags(gb, ctx->waves_info->invert_phase, ctx->waves_info->num_tone_bands);
    }

    ctx->waves_info->tones_index = 0;

    for (ch_num = 0; ch_num < num_channels; ch_num++) {
        for (i = 0; i < ctx->waves_info->num_tone_bands; i++)
            band_has_tones[i] = !ch_num ? 1 : !ctx->waves_info->tone_sharing[i];

        decode_tones_envelope(gb, ctx, ch_num, band_has_tones);
        if ((ret = decode_band_numwavs(gb, ctx, ch_num, band_has_tones,
                                       avctx)) < 0)
            return ret;

        decode_tones_frequency(gb, ctx, ch_num, band_has_tones);
        decode_tones_amplitude(gb, ctx, ch_num, band_has_tones);
        decode_tones_phase(gb, ctx, ch_num, band_has_tones);
    }

    if (num_channels == 2) {
        for (i = 0; i < ctx->waves_info->num_tone_bands; i++) {
            if (ctx->waves_info->tone_sharing[i])
                ctx->channels[1].tones_info[i] = ctx->channels[0].tones_info[i];

            if (ctx->waves_info->tone_master[i])
                FFSWAP(Atrac3pWavesData, ctx->channels[0].tones_info[i],
                       ctx->channels[1].tones_info[i]);
        }
    }

    return 0;
}

int ff_atrac3p_decode_channel_unit(GetBitContext *gb, Atrac3pChanUnitCtx *ctx,
                                   int num_channels, AVCodecContext *avctx)
{
    int ret;

    /* parse sound header */
    ctx->num_quant_units = get_bits(gb, 5) + 1;
    if (ctx->num_quant_units > 28 && ctx->num_quant_units < 32) {
        av_log(avctx, AV_LOG_ERROR,
               "Invalid number of quantization units: %d!\n",
               ctx->num_quant_units);
        return AVERROR_INVALIDDATA;
    }

    ctx->mute_flag = get_bits1(gb);

    /* decode various sound parameters */
    if ((ret = decode_quant_wordlen(gb, ctx, num_channels, avctx)) < 0)
        return ret;

    ctx->num_subbands       = atrac3p_qu_to_subband[ctx->num_quant_units - 1] + 1;
    ctx->num_coded_subbands = ctx->used_quant_units
                              ? atrac3p_qu_to_subband[ctx->used_quant_units - 1] + 1
                              : 0;

    if ((ret = decode_scale_factors(gb, ctx, num_channels, avctx)) < 0)
        return ret;

    if ((ret = decode_code_table_indexes(gb, ctx, num_channels, avctx)) < 0)
        return ret;

    decode_spectrum(gb, ctx, num_channels, avctx);

    if (num_channels == 2) {
        get_subband_flags(gb, ctx->swap_channels, ctx->num_coded_subbands);
        get_subband_flags(gb, ctx->negate_coeffs, ctx->num_coded_subbands);
    }

    decode_window_shape(gb, ctx, num_channels);

    if ((ret = decode_gainc_data(gb, ctx, num_channels, avctx)) < 0)
        return ret;

    if ((ret = decode_tones_info(gb, ctx, num_channels, avctx)) < 0)
        return ret;

    /* decode global noise info */
    ctx->noise_present = get_bits1(gb);
    if (ctx->noise_present) {
        ctx->noise_level_index = get_bits(gb, 4);
        ctx->noise_table_index = get_bits(gb, 4);
    }

    return 0;
}