FFmpeg/libavcodec/dcadec.c

/*
 * DCA compatible decoder
 * Copyright (C) 2004 Gildas Bazin
 * Copyright (C) 2004 Benjamin Zores
 * Copyright (C) 2006 Benjamin Larsson
 * Copyright (C) 2007 Konstantin Shishkov
 *
 * This file is part of Libav.
 *
 * Libav is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * Libav is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with Libav; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

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

#include "libavutil/common.h"
#include "libavutil/float_dsp.h"
#include "libavutil/intmath.h"
#include "libavutil/intreadwrite.h"
#include "libavutil/mathematics.h"
#include "libavutil/audioconvert.h"
#include "avcodec.h"
#include "dsputil.h"
#include "fft.h"
#include "get_bits.h"
#include "put_bits.h"
#include "dcadata.h"
#include "dcahuff.h"
#include "dca.h"
#include "dca_parser.h"
#include "synth_filter.h"
#include "dcadsp.h"
#include "fmtconvert.h"

#if ARCH_ARM
#   include "arm/dca.h"
#endif

//#define TRACE

#define DCA_PRIM_CHANNELS_MAX  (7)
#define DCA_SUBBANDS          (32)
#define DCA_ABITS_MAX         (32)      /* Should be 28 */
#define DCA_SUBSUBFRAMES_MAX   (4)
#define DCA_SUBFRAMES_MAX     (16)
#define DCA_BLOCKS_MAX        (16)
#define DCA_LFE_MAX            (3)

enum DCAMode {
    DCA_MONO = 0,
    DCA_CHANNEL,
    DCA_STEREO,
    DCA_STEREO_SUMDIFF,
    DCA_STEREO_TOTAL,
    DCA_3F,
    DCA_2F1R,
    DCA_3F1R,
    DCA_2F2R,
    DCA_3F2R,
    DCA_4F2R
};

/* these are unconfirmed but should be mostly correct */
enum DCAExSSSpeakerMask {
    DCA_EXSS_FRONT_CENTER          = 0x0001,
    DCA_EXSS_FRONT_LEFT_RIGHT      = 0x0002,
    DCA_EXSS_SIDE_REAR_LEFT_RIGHT  = 0x0004,
    DCA_EXSS_LFE                   = 0x0008,
    DCA_EXSS_REAR_CENTER           = 0x0010,
    DCA_EXSS_FRONT_HIGH_LEFT_RIGHT = 0x0020,
    DCA_EXSS_REAR_LEFT_RIGHT       = 0x0040,
    DCA_EXSS_FRONT_HIGH_CENTER     = 0x0080,
    DCA_EXSS_OVERHEAD              = 0x0100,
    DCA_EXSS_CENTER_LEFT_RIGHT     = 0x0200,
    DCA_EXSS_WIDE_LEFT_RIGHT       = 0x0400,
    DCA_EXSS_SIDE_LEFT_RIGHT       = 0x0800,
    DCA_EXSS_LFE2                  = 0x1000,
    DCA_EXSS_SIDE_HIGH_LEFT_RIGHT  = 0x2000,
    DCA_EXSS_REAR_HIGH_CENTER      = 0x4000,
    DCA_EXSS_REAR_HIGH_LEFT_RIGHT  = 0x8000,
};

enum DCAExtensionMask {
    DCA_EXT_CORE       = 0x001, ///< core in core substream
    DCA_EXT_XXCH       = 0x002, ///< XXCh channels extension in core substream
    DCA_EXT_X96        = 0x004, ///< 96/24 extension in core substream
    DCA_EXT_XCH        = 0x008, ///< XCh channel extension in core substream
    DCA_EXT_EXSS_CORE  = 0x010, ///< core in ExSS (extension substream)
    DCA_EXT_EXSS_XBR   = 0x020, ///< extended bitrate extension in ExSS
    DCA_EXT_EXSS_XXCH  = 0x040, ///< XXCh channels extension in ExSS
    DCA_EXT_EXSS_X96   = 0x080, ///< 96/24 extension in ExSS
    DCA_EXT_EXSS_LBR   = 0x100, ///< low bitrate component in ExSS
    DCA_EXT_EXSS_XLL   = 0x200, ///< lossless extension in ExSS
};

/* -1 are reserved or unknown */
static const int dca_ext_audio_descr_mask[] = {
    DCA_EXT_XCH,
    -1,
    DCA_EXT_X96,
    DCA_EXT_XCH | DCA_EXT_X96,
    -1,
    -1,
    DCA_EXT_XXCH,
    -1,
};

/* extensions that reside in core substream */
#define DCA_CORE_EXTS (DCA_EXT_XCH | DCA_EXT_XXCH | DCA_EXT_X96)

/* Tables for mapping dts channel configurations to libavcodec multichannel api.
 * Some compromises have been made for special configurations. Most configurations
 * are never used so complete accuracy is not needed.
 *
 * L = left, R = right, C = center, S = surround, F = front, R = rear, T = total, OV = overhead.
 * S  -> side, when both rear and back are configured move one of them to the side channel
 * OV -> center back
 * All 2 channel configurations -> AV_CH_LAYOUT_STEREO
 */
static const uint64_t dca_core_channel_layout[] = {
    AV_CH_FRONT_CENTER,                                                     ///< 1, A
    AV_CH_LAYOUT_STEREO,                                                    ///< 2, A + B (dual mono)
    AV_CH_LAYOUT_STEREO,                                                    ///< 2, L + R (stereo)
    AV_CH_LAYOUT_STEREO,                                                    ///< 2, (L + R) + (L - R) (sum-difference)
    AV_CH_LAYOUT_STEREO,                                                    ///< 2, LT + RT (left and right total)
    AV_CH_LAYOUT_STEREO | AV_CH_FRONT_CENTER,                               ///< 3, C + L + R
    AV_CH_LAYOUT_STEREO | AV_CH_BACK_CENTER,                                ///< 3, L + R + S
    AV_CH_LAYOUT_STEREO | AV_CH_FRONT_CENTER | AV_CH_BACK_CENTER,           ///< 4, C + L + R + S
    AV_CH_LAYOUT_STEREO | AV_CH_SIDE_LEFT | AV_CH_SIDE_RIGHT,               ///< 4, L + R + SL + SR

    AV_CH_LAYOUT_STEREO | AV_CH_FRONT_CENTER | AV_CH_SIDE_LEFT |
    AV_CH_SIDE_RIGHT,                                                       ///< 5, C + L + R + SL + SR

    AV_CH_LAYOUT_STEREO | AV_CH_SIDE_LEFT | AV_CH_SIDE_RIGHT |
    AV_CH_FRONT_LEFT_OF_CENTER | AV_CH_FRONT_RIGHT_OF_CENTER,               ///< 6, CL + CR + L + R + SL + SR

    AV_CH_LAYOUT_STEREO | AV_CH_BACK_LEFT | AV_CH_BACK_RIGHT |
    AV_CH_FRONT_CENTER  | AV_CH_BACK_CENTER,                                ///< 6, C + L + R + LR + RR + OV

    AV_CH_FRONT_CENTER | AV_CH_FRONT_RIGHT_OF_CENTER |
    AV_CH_FRONT_LEFT_OF_CENTER | AV_CH_BACK_CENTER   |
    AV_CH_BACK_LEFT | AV_CH_BACK_RIGHT,                                     ///< 6, CF + CR + LF + RF + LR + RR

    AV_CH_FRONT_LEFT_OF_CENTER | AV_CH_FRONT_CENTER   |
    AV_CH_FRONT_RIGHT_OF_CENTER | AV_CH_LAYOUT_STEREO |
    AV_CH_SIDE_LEFT | AV_CH_SIDE_RIGHT,                                     ///< 7, CL + C + CR + L + R + SL + SR

    AV_CH_FRONT_LEFT_OF_CENTER | AV_CH_FRONT_RIGHT_OF_CENTER |
    AV_CH_LAYOUT_STEREO | AV_CH_SIDE_LEFT | AV_CH_SIDE_RIGHT |
    AV_CH_BACK_LEFT | AV_CH_BACK_RIGHT,                                     ///< 8, CL + CR + L + R + SL1 + SL2 + SR1 + SR2

    AV_CH_FRONT_LEFT_OF_CENTER | AV_CH_FRONT_CENTER   |
    AV_CH_FRONT_RIGHT_OF_CENTER | AV_CH_LAYOUT_STEREO |
    AV_CH_SIDE_LEFT | AV_CH_BACK_CENTER | AV_CH_SIDE_RIGHT,                 ///< 8, CL + C + CR + L + R + SL + S + SR
};

static const int8_t dca_lfe_index[] = {
    1, 2, 2, 2, 2, 3, 2, 3, 2, 3, 2, 3, 1, 3, 2, 3
};

static const int8_t dca_channel_reorder_lfe[][9] = {
    { 0, -1, -1, -1, -1, -1, -1, -1, -1},
    { 0,  1, -1, -1, -1, -1, -1, -1, -1},
    { 0,  1, -1, -1, -1, -1, -1, -1, -1},
    { 0,  1, -1, -1, -1, -1, -1, -1, -1},
    { 0,  1, -1, -1, -1, -1, -1, -1, -1},
    { 2,  0,  1, -1, -1, -1, -1, -1, -1},
    { 0,  1,  3, -1, -1, -1, -1, -1, -1},
    { 2,  0,  1,  4, -1, -1, -1, -1, -1},
    { 0,  1,  3,  4, -1, -1, -1, -1, -1},
    { 2,  0,  1,  4,  5, -1, -1, -1, -1},
    { 3,  4,  0,  1,  5,  6, -1, -1, -1},
    { 2,  0,  1,  4,  5,  6, -1, -1, -1},
    { 0,  6,  4,  5,  2,  3, -1, -1, -1},
    { 4,  2,  5,  0,  1,  6,  7, -1, -1},
    { 5,  6,  0,  1,  7,  3,  8,  4, -1},
    { 4,  2,  5,  0,  1,  6,  8,  7, -1},
};

static const int8_t dca_channel_reorder_lfe_xch[][9] = {
    { 0,  2, -1, -1, -1, -1, -1, -1, -1},
    { 0,  1,  3, -1, -1, -1, -1, -1, -1},
    { 0,  1,  3, -1, -1, -1, -1, -1, -1},
    { 0,  1,  3, -1, -1, -1, -1, -1, -1},
    { 0,  1,  3, -1, -1, -1, -1, -1, -1},
    { 2,  0,  1,  4, -1, -1, -1, -1, -1},
    { 0,  1,  3,  4, -1, -1, -1, -1, -1},
    { 2,  0,  1,  4,  5, -1, -1, -1, -1},
    { 0,  1,  4,  5,  3, -1, -1, -1, -1},
    { 2,  0,  1,  5,  6,  4, -1, -1, -1},
    { 3,  4,  0,  1,  6,  7,  5, -1, -1},
    { 2,  0,  1,  4,  5,  6,  7, -1, -1},
    { 0,  6,  4,  5,  2,  3,  7, -1, -1},
    { 4,  2,  5,  0,  1,  7,  8,  6, -1},
    { 5,  6,  0,  1,  8,  3,  9,  4,  7},
    { 4,  2,  5,  0,  1,  6,  9,  8,  7},
};

static const int8_t dca_channel_reorder_nolfe[][9] = {
    { 0, -1, -1, -1, -1, -1, -1, -1, -1},
    { 0,  1, -1, -1, -1, -1, -1, -1, -1},
    { 0,  1, -1, -1, -1, -1, -1, -1, -1},
    { 0,  1, -1, -1, -1, -1, -1, -1, -1},
    { 0,  1, -1, -1, -1, -1, -1, -1, -1},
    { 2,  0,  1, -1, -1, -1, -1, -1, -1},
    { 0,  1,  2, -1, -1, -1, -1, -1, -1},
    { 2,  0,  1,  3, -1, -1, -1, -1, -1},
    { 0,  1,  2,  3, -1, -1, -1, -1, -1},
    { 2,  0,  1,  3,  4, -1, -1, -1, -1},
    { 2,  3,  0,  1,  4,  5, -1, -1, -1},
    { 2,  0,  1,  3,  4,  5, -1, -1, -1},
    { 0,  5,  3,  4,  1,  2, -1, -1, -1},
    { 3,  2,  4,  0,  1,  5,  6, -1, -1},
    { 4,  5,  0,  1,  6,  2,  7,  3, -1},
    { 3,  2,  4,  0,  1,  5,  7,  6, -1},
};

static const int8_t dca_channel_reorder_nolfe_xch[][9] = {
    { 0,  1, -1, -1, -1, -1, -1, -1, -1},
    { 0,  1,  2, -1, -1, -1, -1, -1, -1},
    { 0,  1,  2, -1, -1, -1, -1, -1, -1},
    { 0,  1,  2, -1, -1, -1, -1, -1, -1},
    { 0,  1,  2, -1, -1, -1, -1, -1, -1},
    { 2,  0,  1,  3, -1, -1, -1, -1, -1},
    { 0,  1,  2,  3, -1, -1, -1, -1, -1},
    { 2,  0,  1,  3,  4, -1, -1, -1, -1},
    { 0,  1,  3,  4,  2, -1, -1, -1, -1},
    { 2,  0,  1,  4,  5,  3, -1, -1, -1},
    { 2,  3,  0,  1,  5,  6,  4, -1, -1},
    { 2,  0,  1,  3,  4,  5,  6, -1, -1},
    { 0,  5,  3,  4,  1,  2,  6, -1, -1},
    { 3,  2,  4,  0,  1,  6,  7,  5, -1},
    { 4,  5,  0,  1,  7,  2,  8,  3,  6},
    { 3,  2,  4,  0,  1,  5,  8,  7,  6},
};

#define DCA_DOLBY                  101           /* FIXME */

#define DCA_CHANNEL_BITS             6
#define DCA_CHANNEL_MASK          0x3F

#define DCA_LFE                   0x80

#define HEADER_SIZE                 14

#define DCA_MAX_FRAME_SIZE       16384
#define DCA_MAX_EXSS_HEADER_SIZE  4096

#define DCA_BUFFER_PADDING_SIZE   1024

/** Bit allocation */
typedef struct {
    int offset;                 ///< code values offset
    int maxbits[8];             ///< max bits in VLC
    int wrap;                   ///< wrap for get_vlc2()
    VLC vlc[8];                 ///< actual codes
} BitAlloc;

static BitAlloc dca_bitalloc_index;    ///< indexes for samples VLC select
static BitAlloc dca_tmode;             ///< transition mode VLCs
static BitAlloc dca_scalefactor;       ///< scalefactor VLCs
static BitAlloc dca_smpl_bitalloc[11]; ///< samples VLCs

static av_always_inline int get_bitalloc(GetBitContext *gb, BitAlloc *ba,
                                         int idx)
{
    return get_vlc2(gb, ba->vlc[idx].table, ba->vlc[idx].bits, ba->wrap) +
           ba->offset;
}

typedef struct {
    AVCodecContext *avctx;
    AVFrame frame;
    /* Frame header */
    int frame_type;             ///< type of the current frame
    int samples_deficit;        ///< deficit sample count
    int crc_present;            ///< crc is present in the bitstream
    int sample_blocks;          ///< number of PCM sample blocks
    int frame_size;             ///< primary frame byte size
    int amode;                  ///< audio channels arrangement
    int sample_rate;            ///< audio sampling rate
    int bit_rate;               ///< transmission bit rate
    int bit_rate_index;         ///< transmission bit rate index

    int downmix;                ///< embedded downmix enabled
    int dynrange;               ///< embedded dynamic range flag
    int timestamp;              ///< embedded time stamp flag
    int aux_data;               ///< auxiliary data flag
    int hdcd;                   ///< source material is mastered in HDCD
    int ext_descr;              ///< extension audio descriptor flag
    int ext_coding;             ///< extended coding flag
    int aspf;                   ///< audio sync word insertion flag
    int lfe;                    ///< low frequency effects flag
    int predictor_history;      ///< predictor history flag
    int header_crc;             ///< header crc check bytes
    int multirate_inter;        ///< multirate interpolator switch
    int version;                ///< encoder software revision
    int copy_history;           ///< copy history
    int source_pcm_res;         ///< source pcm resolution
    int front_sum;              ///< front sum/difference flag
    int surround_sum;           ///< surround sum/difference flag
    int dialog_norm;            ///< dialog normalisation parameter

    /* Primary audio coding header */
    int subframes;              ///< number of subframes
    int is_channels_set;        ///< check for if the channel number is already set
    int total_channels;         ///< number of channels including extensions
    int prim_channels;          ///< number of primary audio channels
    int subband_activity[DCA_PRIM_CHANNELS_MAX];    ///< subband activity count
    int vq_start_subband[DCA_PRIM_CHANNELS_MAX];    ///< high frequency vq start subband
    int joint_intensity[DCA_PRIM_CHANNELS_MAX];     ///< joint intensity coding index
    int transient_huffman[DCA_PRIM_CHANNELS_MAX];   ///< transient mode code book
    int scalefactor_huffman[DCA_PRIM_CHANNELS_MAX]; ///< scale factor code book
    int bitalloc_huffman[DCA_PRIM_CHANNELS_MAX];    ///< bit allocation quantizer select
    int quant_index_huffman[DCA_PRIM_CHANNELS_MAX][DCA_ABITS_MAX]; ///< quantization index codebook select
    float scalefactor_adj[DCA_PRIM_CHANNELS_MAX][DCA_ABITS_MAX];   ///< scale factor adjustment

    /* Primary audio coding side information */
    int subsubframes[DCA_SUBFRAMES_MAX];                         ///< number of subsubframes
    int partial_samples[DCA_SUBFRAMES_MAX];                      ///< partial subsubframe samples count
    int prediction_mode[DCA_PRIM_CHANNELS_MAX][DCA_SUBBANDS];    ///< prediction mode (ADPCM used or not)
    int prediction_vq[DCA_PRIM_CHANNELS_MAX][DCA_SUBBANDS];      ///< prediction VQ coefs
    int bitalloc[DCA_PRIM_CHANNELS_MAX][DCA_SUBBANDS];           ///< bit allocation index
    int transition_mode[DCA_PRIM_CHANNELS_MAX][DCA_SUBBANDS];    ///< transition mode (transients)
    int scale_factor[DCA_PRIM_CHANNELS_MAX][DCA_SUBBANDS][2];    ///< scale factors (2 if transient)
    int joint_huff[DCA_PRIM_CHANNELS_MAX];                       ///< joint subband scale factors codebook
    int joint_scale_factor[DCA_PRIM_CHANNELS_MAX][DCA_SUBBANDS]; ///< joint subband scale factors
    int downmix_coef[DCA_PRIM_CHANNELS_MAX][2];                  ///< stereo downmix coefficients
    int dynrange_coef;                                           ///< dynamic range coefficient

    int high_freq_vq[DCA_PRIM_CHANNELS_MAX][DCA_SUBBANDS];       ///< VQ encoded high frequency subbands

    float lfe_data[2 * DCA_LFE_MAX * (DCA_BLOCKS_MAX + 4)];      ///< Low frequency effect data
    int lfe_scale_factor;

    /* Subband samples history (for ADPCM) */
    DECLARE_ALIGNED(16, float, subband_samples_hist)[DCA_PRIM_CHANNELS_MAX][DCA_SUBBANDS][4];
    DECLARE_ALIGNED(32, float, subband_fir_hist)[DCA_PRIM_CHANNELS_MAX][512];
    DECLARE_ALIGNED(32, float, subband_fir_noidea)[DCA_PRIM_CHANNELS_MAX][32];
    int hist_index[DCA_PRIM_CHANNELS_MAX];
    DECLARE_ALIGNED(32, float, raXin)[32];

    int output;                 ///< type of output
    float scale_bias;           ///< output scale

    DECLARE_ALIGNED(32, float, subband_samples)[DCA_BLOCKS_MAX][DCA_PRIM_CHANNELS_MAX][DCA_SUBBANDS][8];
    DECLARE_ALIGNED(32, float, samples)[(DCA_PRIM_CHANNELS_MAX + 1) * 256];
    const float *samples_chanptr[DCA_PRIM_CHANNELS_MAX + 1];

    uint8_t dca_buffer[DCA_MAX_FRAME_SIZE + DCA_MAX_EXSS_HEADER_SIZE + DCA_BUFFER_PADDING_SIZE];
    int dca_buffer_size;        ///< how much data is in the dca_buffer

    const int8_t *channel_order_tab;  ///< channel reordering table, lfe and non lfe
    GetBitContext gb;
    /* Current position in DCA frame */
    int current_subframe;
    int current_subsubframe;

    int core_ext_mask;          ///< present extensions in the core substream

    /* XCh extension information */
    int xch_present;            ///< XCh extension present and valid
    int xch_base_channel;       ///< index of first (only) channel containing XCH data

    /* ExSS header parser */
    int static_fields;          ///< static fields present
    int mix_metadata;           ///< mixing metadata present
    int num_mix_configs;        ///< number of mix out configurations
    int mix_config_num_ch[4];   ///< number of channels in each mix out configuration

    int profile;

    int debug_flag;             ///< used for suppressing repeated error messages output
    AVFloatDSPContext fdsp;
    FFTContext imdct;
    SynthFilterContext synth;
    DCADSPContext dcadsp;
    FmtConvertContext fmt_conv;
} DCAContext;

static const uint16_t dca_vlc_offs[] = {
        0,   512,   640,   768,  1282,  1794,  2436,  3080,  3770,  4454,  5364,
     5372,  5380,  5388,  5392,  5396,  5412,  5420,  5428,  5460,  5492,  5508,
     5572,  5604,  5668,  5796,  5860,  5892,  6412,  6668,  6796,  7308,  7564,
     7820,  8076,  8620,  9132,  9388,  9910, 10166, 10680, 11196, 11726, 12240,
    12752, 13298, 13810, 14326, 14840, 15500, 16022, 16540, 17158, 17678, 18264,
    18796, 19352, 19926, 20468, 21472, 22398, 23014, 23622,
};

static av_cold void dca_init_vlcs(void)
{
    static int vlcs_initialized = 0;
    int i, j, c = 14;
    static VLC_TYPE dca_table[23622][2];

    if (vlcs_initialized)
        return;

    dca_bitalloc_index.offset = 1;
    dca_bitalloc_index.wrap = 2;
    for (i = 0; i < 5; i++) {
        dca_bitalloc_index.vlc[i].table = &dca_table[dca_vlc_offs[i]];
        dca_bitalloc_index.vlc[i].table_allocated = dca_vlc_offs[i + 1] - dca_vlc_offs[i];
        init_vlc(&dca_bitalloc_index.vlc[i], bitalloc_12_vlc_bits[i], 12,
                 bitalloc_12_bits[i], 1, 1,
                 bitalloc_12_codes[i], 2, 2, INIT_VLC_USE_NEW_STATIC);
    }
    dca_scalefactor.offset = -64;
    dca_scalefactor.wrap = 2;
    for (i = 0; i < 5; i++) {
        dca_scalefactor.vlc[i].table = &dca_table[dca_vlc_offs[i + 5]];
        dca_scalefactor.vlc[i].table_allocated = dca_vlc_offs[i + 6] - dca_vlc_offs[i + 5];
        init_vlc(&dca_scalefactor.vlc[i], SCALES_VLC_BITS, 129,
                 scales_bits[i], 1, 1,
                 scales_codes[i], 2, 2, INIT_VLC_USE_NEW_STATIC);
    }
    dca_tmode.offset = 0;
    dca_tmode.wrap = 1;
    for (i = 0; i < 4; i++) {
        dca_tmode.vlc[i].table = &dca_table[dca_vlc_offs[i + 10]];
        dca_tmode.vlc[i].table_allocated = dca_vlc_offs[i + 11] - dca_vlc_offs[i + 10];
        init_vlc(&dca_tmode.vlc[i], tmode_vlc_bits[i], 4,
                 tmode_bits[i], 1, 1,
                 tmode_codes[i], 2, 2, INIT_VLC_USE_NEW_STATIC);
    }

    for (i = 0; i < 10; i++)
        for (j = 0; j < 7; j++) {
            if (!bitalloc_codes[i][j])
                break;
            dca_smpl_bitalloc[i + 1].offset                 = bitalloc_offsets[i];
            dca_smpl_bitalloc[i + 1].wrap                   = 1 + (j > 4);
            dca_smpl_bitalloc[i + 1].vlc[j].table           = &dca_table[dca_vlc_offs[c]];
            dca_smpl_bitalloc[i + 1].vlc[j].table_allocated = dca_vlc_offs[c + 1] - dca_vlc_offs[c];

            init_vlc(&dca_smpl_bitalloc[i + 1].vlc[j], bitalloc_maxbits[i][j],
                     bitalloc_sizes[i],
                     bitalloc_bits[i][j], 1, 1,
                     bitalloc_codes[i][j], 2, 2, INIT_VLC_USE_NEW_STATIC);
            c++;
        }
    vlcs_initialized = 1;
}

static inline void get_array(GetBitContext *gb, int *dst, int len, int bits)
{
    while (len--)
        *dst++ = get_bits(gb, bits);
}

static int dca_parse_audio_coding_header(DCAContext *s, int base_channel)
{
    int i, j;
    static const float adj_table[4] = { 1.0, 1.1250, 1.2500, 1.4375 };
    static const int bitlen[11] = { 0, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3 };
    static const int thr[11]    = { 0, 1, 3, 3, 3, 3, 7, 7, 7, 7, 7 };

    s->total_channels = get_bits(&s->gb, 3) + 1 + base_channel;
    s->prim_channels  = s->total_channels;

    if (s->prim_channels > DCA_PRIM_CHANNELS_MAX)
        s->prim_channels = DCA_PRIM_CHANNELS_MAX;


    for (i = base_channel; i < s->prim_channels; i++) {
        s->subband_activity[i] = get_bits(&s->gb, 5) + 2;
        if (s->subband_activity[i] > DCA_SUBBANDS)
            s->subband_activity[i] = DCA_SUBBANDS;
    }
    for (i = base_channel; i < s->prim_channels; i++) {
        s->vq_start_subband[i] = get_bits(&s->gb, 5) + 1;
        if (s->vq_start_subband[i] > DCA_SUBBANDS)
            s->vq_start_subband[i] = DCA_SUBBANDS;
    }
    get_array(&s->gb, s->joint_intensity + base_channel,     s->prim_channels - base_channel, 3);
    get_array(&s->gb, s->transient_huffman + base_channel,   s->prim_channels - base_channel, 2);
    get_array(&s->gb, s->scalefactor_huffman + base_channel, s->prim_channels - base_channel, 3);
    get_array(&s->gb, s->bitalloc_huffman + base_channel,    s->prim_channels - base_channel, 3);

    /* Get codebooks quantization indexes */
    if (!base_channel)
        memset(s->quant_index_huffman, 0, sizeof(s->quant_index_huffman));
    for (j = 1; j < 11; j++)
        for (i = base_channel; i < s->prim_channels; i++)
            s->quant_index_huffman[i][j] = get_bits(&s->gb, bitlen[j]);

    /* Get scale factor adjustment */
    for (j = 0; j < 11; j++)
        for (i = base_channel; i < s->prim_channels; i++)
            s->scalefactor_adj[i][j] = 1;

    for (j = 1; j < 11; j++)
        for (i = base_channel; i < s->prim_channels; i++)
            if (s->quant_index_huffman[i][j] < thr[j])
                s->scalefactor_adj[i][j] = adj_table[get_bits(&s->gb, 2)];

    if (s->crc_present) {
        /* Audio header CRC check */
        get_bits(&s->gb, 16);
    }

    s->current_subframe    = 0;
    s->current_subsubframe = 0;

#ifdef TRACE
    av_log(s->avctx, AV_LOG_DEBUG, "subframes: %i\n", s->subframes);
    av_log(s->avctx, AV_LOG_DEBUG, "prim channels: %i\n", s->prim_channels);
    for (i = base_channel; i < s->prim_channels; i++) {
        av_log(s->avctx, AV_LOG_DEBUG, "subband activity: %i\n",
               s->subband_activity[i]);
        av_log(s->avctx, AV_LOG_DEBUG, "vq start subband: %i\n",
               s->vq_start_subband[i]);
        av_log(s->avctx, AV_LOG_DEBUG, "joint intensity: %i\n",
               s->joint_intensity[i]);
        av_log(s->avctx, AV_LOG_DEBUG, "transient mode codebook: %i\n",
               s->transient_huffman[i]);
        av_log(s->avctx, AV_LOG_DEBUG, "scale factor codebook: %i\n",
               s->scalefactor_huffman[i]);
        av_log(s->avctx, AV_LOG_DEBUG, "bit allocation quantizer: %i\n",
               s->bitalloc_huffman[i]);
        av_log(s->avctx, AV_LOG_DEBUG, "quant index huff:");
        for (j = 0; j < 11; j++)
            av_log(s->avctx, AV_LOG_DEBUG, " %i", s->quant_index_huffman[i][j]);
        av_log(s->avctx, AV_LOG_DEBUG, "\n");
        av_log(s->avctx, AV_LOG_DEBUG, "scalefac adj:");
        for (j = 0; j < 11; j++)
            av_log(s->avctx, AV_LOG_DEBUG, " %1.3f", s->scalefactor_adj[i][j]);
        av_log(s->avctx, AV_LOG_DEBUG, "\n");
    }
#endif

    return 0;
}

static int dca_parse_frame_header(DCAContext *s)
{
    init_get_bits(&s->gb, s->dca_buffer, s->dca_buffer_size * 8);

    /* Sync code */
    skip_bits_long(&s->gb, 32);

    /* Frame header */
    s->frame_type        = get_bits(&s->gb, 1);
    s->samples_deficit   = get_bits(&s->gb, 5) + 1;
    s->crc_present       = get_bits(&s->gb, 1);
    s->sample_blocks     = get_bits(&s->gb, 7) + 1;
    s->frame_size        = get_bits(&s->gb, 14) + 1;
    if (s->frame_size < 95)
        return AVERROR_INVALIDDATA;
    s->amode             = get_bits(&s->gb, 6);
    s->sample_rate       = avpriv_dca_sample_rates[get_bits(&s->gb, 4)];
    if (!s->sample_rate)
        return AVERROR_INVALIDDATA;
    s->bit_rate_index    = get_bits(&s->gb, 5);
    s->bit_rate          = dca_bit_rates[s->bit_rate_index];
    if (!s->bit_rate)
        return AVERROR_INVALIDDATA;

    s->downmix           = get_bits(&s->gb, 1);
    s->dynrange          = get_bits(&s->gb, 1);
    s->timestamp         = get_bits(&s->gb, 1);
    s->aux_data          = get_bits(&s->gb, 1);
    s->hdcd              = get_bits(&s->gb, 1);
    s->ext_descr         = get_bits(&s->gb, 3);
    s->ext_coding        = get_bits(&s->gb, 1);
    s->aspf              = get_bits(&s->gb, 1);
    s->lfe               = get_bits(&s->gb, 2);
    s->predictor_history = get_bits(&s->gb, 1);

    /* TODO: check CRC */
    if (s->crc_present)
        s->header_crc    = get_bits(&s->gb, 16);

    s->multirate_inter   = get_bits(&s->gb, 1);
    s->version           = get_bits(&s->gb, 4);
    s->copy_history      = get_bits(&s->gb, 2);
    s->source_pcm_res    = get_bits(&s->gb, 3);
    s->front_sum         = get_bits(&s->gb, 1);
    s->surround_sum      = get_bits(&s->gb, 1);
    s->dialog_norm       = get_bits(&s->gb, 4);

    /* FIXME: channels mixing levels */
    s->output = s->amode;
    if (s->lfe)
        s->output |= DCA_LFE;

#ifdef TRACE
    av_log(s->avctx, AV_LOG_DEBUG, "frame type: %i\n", s->frame_type);
    av_log(s->avctx, AV_LOG_DEBUG, "samples deficit: %i\n", s->samples_deficit);
    av_log(s->avctx, AV_LOG_DEBUG, "crc present: %i\n", s->crc_present);
    av_log(s->avctx, AV_LOG_DEBUG, "sample blocks: %i (%i samples)\n",
           s->sample_blocks, s->sample_blocks * 32);
    av_log(s->avctx, AV_LOG_DEBUG, "frame size: %i bytes\n", s->frame_size);
    av_log(s->avctx, AV_LOG_DEBUG, "amode: %i (%i channels)\n",
           s->amode, dca_channels[s->amode]);
    av_log(s->avctx, AV_LOG_DEBUG, "sample rate: %i Hz\n",
           s->sample_rate);
    av_log(s->avctx, AV_LOG_DEBUG, "bit rate: %i bits/s\n",
           s->bit_rate);
    av_log(s->avctx, AV_LOG_DEBUG, "downmix: %i\n", s->downmix);
    av_log(s->avctx, AV_LOG_DEBUG, "dynrange: %i\n", s->dynrange);
    av_log(s->avctx, AV_LOG_DEBUG, "timestamp: %i\n", s->timestamp);
    av_log(s->avctx, AV_LOG_DEBUG, "aux_data: %i\n", s->aux_data);
    av_log(s->avctx, AV_LOG_DEBUG, "hdcd: %i\n", s->hdcd);
    av_log(s->avctx, AV_LOG_DEBUG, "ext descr: %i\n", s->ext_descr);
    av_log(s->avctx, AV_LOG_DEBUG, "ext coding: %i\n", s->ext_coding);
    av_log(s->avctx, AV_LOG_DEBUG, "aspf: %i\n", s->aspf);
    av_log(s->avctx, AV_LOG_DEBUG, "lfe: %i\n", s->lfe);
    av_log(s->avctx, AV_LOG_DEBUG, "predictor history: %i\n",
           s->predictor_history);
    av_log(s->avctx, AV_LOG_DEBUG, "header crc: %i\n", s->header_crc);
    av_log(s->avctx, AV_LOG_DEBUG, "multirate inter: %i\n",
           s->multirate_inter);
    av_log(s->avctx, AV_LOG_DEBUG, "version number: %i\n", s->version);
    av_log(s->avctx, AV_LOG_DEBUG, "copy history: %i\n", s->copy_history);
    av_log(s->avctx, AV_LOG_DEBUG,
           "source pcm resolution: %i (%i bits/sample)\n",
           s->source_pcm_res, dca_bits_per_sample[s->source_pcm_res]);
    av_log(s->avctx, AV_LOG_DEBUG, "front sum: %i\n", s->front_sum);
    av_log(s->avctx, AV_LOG_DEBUG, "surround sum: %i\n", s->surround_sum);
    av_log(s->avctx, AV_LOG_DEBUG, "dialog norm: %i\n", s->dialog_norm);
    av_log(s->avctx, AV_LOG_DEBUG, "\n");
#endif

    /* Primary audio coding header */
    s->subframes         = get_bits(&s->gb, 4) + 1;

    return dca_parse_audio_coding_header(s, 0);
}


static inline int get_scale(GetBitContext *gb, int level, int value, int log2range)
{
    if (level < 5) {
        /* huffman encoded */
        value += get_bitalloc(gb, &dca_scalefactor, level);
        value = av_clip(value, 0, (1 << log2range) - 1);
    } else if (level < 8) {
        if (level + 1 > log2range) {
            skip_bits(gb, level + 1 - log2range);
            value = get_bits(gb, log2range);
        } else {
            value = get_bits(gb, level + 1);
        }
    }
    return value;
}

static int dca_subframe_header(DCAContext *s, int base_channel, int block_index)
{
    /* Primary audio coding side information */
    int j, k;

    if (get_bits_left(&s->gb) < 0)
        return AVERROR_INVALIDDATA;

    if (!base_channel) {
        s->subsubframes[s->current_subframe]    = get_bits(&s->gb, 2) + 1;
        s->partial_samples[s->current_subframe] = get_bits(&s->gb, 3);
    }

    for (j = base_channel; j < s->prim_channels; j++) {
        for (k = 0; k < s->subband_activity[j]; k++)
            s->prediction_mode[j][k] = get_bits(&s->gb, 1);
    }

    /* Get prediction codebook */
    for (j = base_channel; j < s->prim_channels; j++) {
        for (k = 0; k < s->subband_activity[j]; k++) {
            if (s->prediction_mode[j][k] > 0) {
                /* (Prediction coefficient VQ address) */
                s->prediction_vq[j][k] = get_bits(&s->gb, 12);
            }
        }
    }

    /* Bit allocation index */
    for (j = base_channel; j < s->prim_channels; j++) {
        for (k = 0; k < s->vq_start_subband[j]; k++) {
            if (s->bitalloc_huffman[j] == 6)
                s->bitalloc[j][k] = get_bits(&s->gb, 5);
            else if (s->bitalloc_huffman[j] == 5)
                s->bitalloc[j][k] = get_bits(&s->gb, 4);
            else if (s->bitalloc_huffman[j] == 7) {
                av_log(s->avctx, AV_LOG_ERROR,
                       "Invalid bit allocation index\n");
                return AVERROR_INVALIDDATA;
            } else {
                s->bitalloc[j][k] =
                    get_bitalloc(&s->gb, &dca_bitalloc_index, s->bitalloc_huffman[j]);
            }

            if (s->bitalloc[j][k] > 26) {
                // av_log(s->avctx, AV_LOG_DEBUG, "bitalloc index [%i][%i] too big (%i)\n",
                //        j, k, s->bitalloc[j][k]);
                return AVERROR_INVALIDDATA;
            }
        }
    }

    /* Transition mode */
    for (j = base_channel; j < s->prim_channels; j++) {
        for (k = 0; k < s->subband_activity[j]; k++) {
            s->transition_mode[j][k] = 0;
            if (s->subsubframes[s->current_subframe] > 1 &&
                k < s->vq_start_subband[j] && s->bitalloc[j][k] > 0) {
                s->transition_mode[j][k] =
                    get_bitalloc(&s->gb, &dca_tmode, s->transient_huffman[j]);
            }
        }
    }

    if (get_bits_left(&s->gb) < 0)
        return AVERROR_INVALIDDATA;

    for (j = base_channel; j < s->prim_channels; j++) {
        const uint32_t *scale_table;
        int scale_sum, log_size;

        memset(s->scale_factor[j], 0,
               s->subband_activity[j] * sizeof(s->scale_factor[0][0][0]) * 2);

        if (s->scalefactor_huffman[j] == 6) {
            scale_table = scale_factor_quant7;
            log_size = 7;
        } else {
            scale_table = scale_factor_quant6;
            log_size = 6;
        }

        /* When huffman coded, only the difference is encoded */
        scale_sum = 0;

        for (k = 0; k < s->subband_activity[j]; k++) {
            if (k >= s->vq_start_subband[j] || s->bitalloc[j][k] > 0) {
                scale_sum = get_scale(&s->gb, s->scalefactor_huffman[j], scale_sum, log_size);
                s->scale_factor[j][k][0] = scale_table[scale_sum];
            }

            if (k < s->vq_start_subband[j] && s->transition_mode[j][k]) {
                /* Get second scale factor */
                scale_sum = get_scale(&s->gb, s->scalefactor_huffman[j], scale_sum, log_size);
                s->scale_factor[j][k][1] = scale_table[scale_sum];
            }
        }
    }

    /* Joint subband scale factor codebook select */
    for (j = base_channel; j < s->prim_channels; j++) {
        /* Transmitted only if joint subband coding enabled */
        if (s->joint_intensity[j] > 0)
            s->joint_huff[j] = get_bits(&s->gb, 3);
    }

    if (get_bits_left(&s->gb) < 0)
        return AVERROR_INVALIDDATA;

    /* Scale factors for joint subband coding */
    for (j = base_channel; j < s->prim_channels; j++) {
        int source_channel;

        /* Transmitted only if joint subband coding enabled */
        if (s->joint_intensity[j] > 0) {
            int scale = 0;
            source_channel = s->joint_intensity[j] - 1;

            /* When huffman coded, only the difference is encoded
             * (is this valid as well for joint scales ???) */

            for (k = s->subband_activity[j]; k < s->subband_activity[source_channel]; k++) {
                scale = get_scale(&s->gb, s->joint_huff[j], 64 /* bias */, 7);
                s->joint_scale_factor[j][k] = scale;    /*joint_scale_table[scale]; */
            }

            if (!(s->debug_flag & 0x02)) {
                av_log(s->avctx, AV_LOG_DEBUG,
                       "Joint stereo coding not supported\n");
                s->debug_flag |= 0x02;
            }
        }
    }

    /* Stereo downmix coefficients */
    if (!base_channel && s->prim_channels > 2) {
        if (s->downmix) {
            for (j = base_channel; j < s->prim_channels; j++) {
                s->downmix_coef[j][0] = get_bits(&s->gb, 7);
                s->downmix_coef[j][1] = get_bits(&s->gb, 7);
            }
        } else {
            int am = s->amode & DCA_CHANNEL_MASK;
            if (am >= FF_ARRAY_ELEMS(dca_default_coeffs)) {
                av_log(s->avctx, AV_LOG_ERROR,
                       "Invalid channel mode %d\n", am);
                return AVERROR_INVALIDDATA;
            }
            for (j = base_channel; j < s->prim_channels; j++) {
                s->downmix_coef[j][0] = dca_default_coeffs[am][j][0];
                s->downmix_coef[j][1] = dca_default_coeffs[am][j][1];
            }
        }
    }

    /* Dynamic range coefficient */
    if (!base_channel && s->dynrange)
        s->dynrange_coef = get_bits(&s->gb, 8);

    /* Side information CRC check word */
    if (s->crc_present) {
        get_bits(&s->gb, 16);
    }

    /*
     * Primary audio data arrays
     */

    /* VQ encoded high frequency subbands */
    for (j = base_channel; j < s->prim_channels; j++)
        for (k = s->vq_start_subband[j]; k < s->subband_activity[j]; k++)
            /* 1 vector -> 32 samples */
            s->high_freq_vq[j][k] = get_bits(&s->gb, 10);

    /* Low frequency effect data */
    if (!base_channel && s->lfe) {
        /* LFE samples */
        int lfe_samples = 2 * s->lfe * (4 + block_index);
        int lfe_end_sample = 2 * s->lfe * (4 + block_index + s->subsubframes[s->current_subframe]);
        float lfe_scale;

        for (j = lfe_samples; j < lfe_end_sample; j++) {
            /* Signed 8 bits int */
            s->lfe_data[j] = get_sbits(&s->gb, 8);
        }

        /* Scale factor index */
        skip_bits(&s->gb, 1);
        s->lfe_scale_factor = scale_factor_quant7[get_bits(&s->gb, 7)];

        /* Quantization step size * scale factor */
        lfe_scale = 0.035 * s->lfe_scale_factor;

        for (j = lfe_samples; j < lfe_end_sample; j++)
            s->lfe_data[j] *= lfe_scale;
    }

#ifdef TRACE
    av_log(s->avctx, AV_LOG_DEBUG, "subsubframes: %i\n",
           s->subsubframes[s->current_subframe]);
    av_log(s->avctx, AV_LOG_DEBUG, "partial samples: %i\n",
           s->partial_samples[s->current_subframe]);

    for (j = base_channel; j < s->prim_channels; j++) {
        av_log(s->avctx, AV_LOG_DEBUG, "prediction mode:");
        for (k = 0; k < s->subband_activity[j]; k++)
            av_log(s->avctx, AV_LOG_DEBUG, " %i", s->prediction_mode[j][k]);
        av_log(s->avctx, AV_LOG_DEBUG, "\n");
    }
    for (j = base_channel; j < s->prim_channels; j++) {
        for (k = 0; k < s->subband_activity[j]; k++)
            av_log(s->avctx, AV_LOG_DEBUG,
                   "prediction coefs: %f, %f, %f, %f\n",
                   (float) adpcm_vb[s->prediction_vq[j][k]][0] / 8192,
                   (float) adpcm_vb[s->prediction_vq[j][k]][1] / 8192,
                   (float) adpcm_vb[s->prediction_vq[j][k]][2] / 8192,
                   (float) adpcm_vb[s->prediction_vq[j][k]][3] / 8192);
    }
    for (j = base_channel; j < s->prim_channels; j++) {
        av_log(s->avctx, AV_LOG_DEBUG, "bitalloc index: ");
        for (k = 0; k < s->vq_start_subband[j]; k++)
            av_log(s->avctx, AV_LOG_DEBUG, "%2.2i ", s->bitalloc[j][k]);
        av_log(s->avctx, AV_LOG_DEBUG, "\n");
    }
    for (j = base_channel; j < s->prim_channels; j++) {
        av_log(s->avctx, AV_LOG_DEBUG, "Transition mode:");
        for (k = 0; k < s->subband_activity[j]; k++)
            av_log(s->avctx, AV_LOG_DEBUG, " %i", s->transition_mode[j][k]);
        av_log(s->avctx, AV_LOG_DEBUG, "\n");
    }
    for (j = base_channel; j < s->prim_channels; j++) {
        av_log(s->avctx, AV_LOG_DEBUG, "Scale factor:");
        for (k = 0; k < s->subband_activity[j]; k++) {
            if (k >= s->vq_start_subband[j] || s->bitalloc[j][k] > 0)
                av_log(s->avctx, AV_LOG_DEBUG, " %i", s->scale_factor[j][k][0]);
            if (k < s->vq_start_subband[j] && s->transition_mode[j][k])
                av_log(s->avctx, AV_LOG_DEBUG, " %i(t)", s->scale_factor[j][k][1]);
        }
        av_log(s->avctx, AV_LOG_DEBUG, "\n");
    }
    for (j = base_channel; j < s->prim_channels; j++) {
        if (s->joint_intensity[j] > 0) {
            int source_channel = s->joint_intensity[j] - 1;
            av_log(s->avctx, AV_LOG_DEBUG, "Joint scale factor index:\n");
            for (k = s->subband_activity[j]; k < s->subband_activity[source_channel]; k++)
                av_log(s->avctx, AV_LOG_DEBUG, " %i", s->joint_scale_factor[j][k]);
            av_log(s->avctx, AV_LOG_DEBUG, "\n");
        }
    }
    if (!base_channel && s->prim_channels > 2 && s->downmix) {
        av_log(s->avctx, AV_LOG_DEBUG, "Downmix coeffs:\n");
        for (j = 0; j < s->prim_channels; j++) {
            av_log(s->avctx, AV_LOG_DEBUG, "Channel 0, %d = %f\n", j,
                   dca_downmix_coeffs[s->downmix_coef[j][0]]);
            av_log(s->avctx, AV_LOG_DEBUG, "Channel 1, %d = %f\n", j,
                   dca_downmix_coeffs[s->downmix_coef[j][1]]);
        }
        av_log(s->avctx, AV_LOG_DEBUG, "\n");
    }
    for (j = base_channel; j < s->prim_channels; j++)
        for (k = s->vq_start_subband[j]; k < s->subband_activity[j]; k++)
            av_log(s->avctx, AV_LOG_DEBUG, "VQ index: %i\n", s->high_freq_vq[j][k]);
    if (!base_channel && s->lfe) {
        int lfe_samples = 2 * s->lfe * (4 + block_index);
        int lfe_end_sample = 2 * s->lfe * (4 + block_index + s->subsubframes[s->current_subframe]);

        av_log(s->avctx, AV_LOG_DEBUG, "LFE samples:\n");
        for (j = lfe_samples; j < lfe_end_sample; j++)
            av_log(s->avctx, AV_LOG_DEBUG, " %f", s->lfe_data[j]);
        av_log(s->avctx, AV_LOG_DEBUG, "\n");
    }
#endif

    return 0;
}

static void qmf_32_subbands(DCAContext *s, int chans,
                            float samples_in[32][8], float *samples_out,
                            float scale)
{
    const float *prCoeff;
    int i;

    int sb_act = s->subband_activity[chans];
    int subindex;

    scale *= sqrt(1 / 8.0);

    /* Select filter */
    if (!s->multirate_inter)    /* Non-perfect reconstruction */
        prCoeff = fir_32bands_nonperfect;
    else                        /* Perfect reconstruction */
        prCoeff = fir_32bands_perfect;

    for (i = sb_act; i < 32; i++)
        s->raXin[i] = 0.0;

    /* Reconstructed channel sample index */
    for (subindex = 0; subindex < 8; subindex++) {
        /* Load in one sample from each subband and clear inactive subbands */
        for (i = 0; i < sb_act; i++) {
            unsigned sign = (i - 1) & 2;
            uint32_t v    = AV_RN32A(&samples_in[i][subindex]) ^ sign << 30;
            AV_WN32A(&s->raXin[i], v);
        }

        s->synth.synth_filter_float(&s->imdct,
                                    s->subband_fir_hist[chans],
                                    &s->hist_index[chans],
                                    s->subband_fir_noidea[chans], prCoeff,
                                    samples_out, s->raXin, scale);
        samples_out += 32;
    }
}

static void lfe_interpolation_fir(DCAContext *s, int decimation_select,
                                  int num_deci_sample, float *samples_in,
                                  float *samples_out, float scale)
{
    /* samples_in: An array holding decimated samples.
     *   Samples in current subframe starts from samples_in[0],
     *   while samples_in[-1], samples_in[-2], ..., stores samples
     *   from last subframe as history.
     *
     * samples_out: An array holding interpolated samples
     */

    int decifactor;
    const float *prCoeff;
    int deciindex;

    /* Select decimation filter */
    if (decimation_select == 1) {
        decifactor = 64;
        prCoeff = lfe_fir_128;
    } else {
        decifactor = 32;
        prCoeff = lfe_fir_64;
    }
    /* Interpolation */
    for (deciindex = 0; deciindex < num_deci_sample; deciindex++) {
        s->dcadsp.lfe_fir(samples_out, samples_in, prCoeff, decifactor, scale);
        samples_in++;
        samples_out += 2 * decifactor;
    }
}

/* downmixing routines */
#define MIX_REAR1(samples, si1, rs, coef)           \
    samples[i]     += samples[si1] * coef[rs][0];   \
    samples[i+256] += samples[si1] * coef[rs][1];

#define MIX_REAR2(samples, si1, si2, rs, coef)                                     \
    samples[i]     += samples[si1] * coef[rs][0] + samples[si2] * coef[rs + 1][0]; \
    samples[i+256] += samples[si1] * coef[rs][1] + samples[si2] * coef[rs + 1][1];

#define MIX_FRONT3(samples, coef)                                      \
    t = samples[i + c];                                                \
    u = samples[i + l];                                                \
    v = samples[i + r];                                                \
    samples[i]     = t * coef[0][0] + u * coef[1][0] + v * coef[2][0]; \
    samples[i+256] = t * coef[0][1] + u * coef[1][1] + v * coef[2][1];

#define DOWNMIX_TO_STEREO(op1, op2)             \
    for (i = 0; i < 256; i++) {                 \
        op1                                     \
        op2                                     \
    }

static void dca_downmix(float *samples, int srcfmt,
                        int downmix_coef[DCA_PRIM_CHANNELS_MAX][2],
                        const int8_t *channel_mapping)
{
    int c, l, r, sl, sr, s;
    int i;
    float t, u, v;
    float coef[DCA_PRIM_CHANNELS_MAX][2];

    for (i = 0; i < DCA_PRIM_CHANNELS_MAX; i++) {
        coef[i][0] = dca_downmix_coeffs[downmix_coef[i][0]];
        coef[i][1] = dca_downmix_coeffs[downmix_coef[i][1]];
    }

    switch (srcfmt) {
    case DCA_MONO:
    case DCA_CHANNEL:
    case DCA_STEREO_TOTAL:
    case DCA_STEREO_SUMDIFF:
    case DCA_4F2R:
        av_log(NULL, 0, "Not implemented!\n");
        break;
    case DCA_STEREO:
        break;
    case DCA_3F:
        c = channel_mapping[0] * 256;
        l = channel_mapping[1] * 256;
        r = channel_mapping[2] * 256;
        DOWNMIX_TO_STEREO(MIX_FRONT3(samples, coef), );
        break;
    case DCA_2F1R:
        s = channel_mapping[2] * 256;
        DOWNMIX_TO_STEREO(MIX_REAR1(samples, i + s, 2, coef), );
        break;
    case DCA_3F1R:
        c = channel_mapping[0] * 256;
        l = channel_mapping[1] * 256;
        r = channel_mapping[2] * 256;
        s = channel_mapping[3] * 256;
        DOWNMIX_TO_STEREO(MIX_FRONT3(samples, coef),
                          MIX_REAR1(samples, i + s, 3, coef));
        break;
    case DCA_2F2R:
        sl = channel_mapping[2] * 256;
        sr = channel_mapping[3] * 256;
        DOWNMIX_TO_STEREO(MIX_REAR2(samples, i + sl, i + sr, 2, coef), );
        break;
    case DCA_3F2R:
        c  = channel_mapping[0] * 256;
        l  = channel_mapping[1] * 256;
        r  = channel_mapping[2] * 256;
        sl = channel_mapping[3] * 256;
        sr = channel_mapping[4] * 256;
        DOWNMIX_TO_STEREO(MIX_FRONT3(samples, coef),
                          MIX_REAR2(samples, i + sl, i + sr, 3, coef));
        break;
    }
}


#ifndef decode_blockcodes
/* Very compact version of the block code decoder that does not use table
 * look-up but is slightly slower */
static int decode_blockcode(int code, int levels, int *values)
{
    int i;
    int offset = (levels - 1) >> 1;

    for (i = 0; i < 4; i++) {
        int div = FASTDIV(code, levels);
        values[i] = code - offset - div * levels;
        code = div;
    }

    return code;
}

static int decode_blockcodes(int code1, int code2, int levels, int *values)
{
    return decode_blockcode(code1, levels, values) |
           decode_blockcode(code2, levels, values + 4);
}
#endif

static const uint8_t abits_sizes[7]  = { 7, 10, 12, 13, 15, 17, 19 };
static const uint8_t abits_levels[7] = { 3,  5,  7,  9, 13, 17, 25 };

#ifndef int8x8_fmul_int32
static inline void int8x8_fmul_int32(float *dst, const int8_t *src, int scale)
{
    float fscale = scale / 16.0;
    int i;
    for (i = 0; i < 8; i++)
        dst[i] = src[i] * fscale;
}
#endif

static int dca_subsubframe(DCAContext *s, int base_channel, int block_index)
{
    int k, l;
    int subsubframe = s->current_subsubframe;

    const float *quant_step_table;

    /* FIXME */
    float (*subband_samples)[DCA_SUBBANDS][8] = s->subband_samples[block_index];
    LOCAL_ALIGNED_16(int, block, [8]);

    /*
     * Audio data
     */

    /* Select quantization step size table */
    if (s->bit_rate_index == 0x1f)
        quant_step_table = lossless_quant_d;
    else
        quant_step_table = lossy_quant_d;

    for (k = base_channel; k < s->prim_channels; k++) {
        if (get_bits_left(&s->gb) < 0)
            return AVERROR_INVALIDDATA;

        for (l = 0; l < s->vq_start_subband[k]; l++) {
            int m;

            /* Select the mid-tread linear quantizer */
            int abits = s->bitalloc[k][l];

            float quant_step_size = quant_step_table[abits];

            /*
             * Determine quantization index code book and its type
             */

            /* Select quantization index code book */
            int sel = s->quant_index_huffman[k][abits];

            /*
             * Extract bits from the bit stream
             */
            if (!abits) {
                memset(subband_samples[k][l], 0, 8 * sizeof(subband_samples[0][0][0]));
            } else {
                /* Deal with transients */
                int sfi = s->transition_mode[k][l] && subsubframe >= s->transition_mode[k][l];
                float rscale = quant_step_size * s->scale_factor[k][l][sfi] *
                               s->scalefactor_adj[k][sel];

                if (abits >= 11 || !dca_smpl_bitalloc[abits].vlc[sel].table) {
                    if (abits <= 7) {
                        /* Block code */
                        int block_code1, block_code2, size, levels, err;

                        size   = abits_sizes[abits - 1];
                        levels = abits_levels[abits - 1];

                        block_code1 = get_bits(&s->gb, size);
                        block_code2 = get_bits(&s->gb, size);
                        err = decode_blockcodes(block_code1, block_code2,
                                                levels, block);
                        if (err) {
                            av_log(s->avctx, AV_LOG_ERROR,
                                   "ERROR: block code look-up failed\n");
                            return AVERROR_INVALIDDATA;
                        }
                    } else {
                        /* no coding */
                        for (m = 0; m < 8; m++)
                            block[m] = get_sbits(&s->gb, abits - 3);
                    }
                } else {
                    /* Huffman coded */
                    for (m = 0; m < 8; m++)
                        block[m] = get_bitalloc(&s->gb,
                                                &dca_smpl_bitalloc[abits], sel);
                }

                s->fmt_conv.int32_to_float_fmul_scalar(subband_samples[k][l],
                                                       block, rscale, 8);
            }

            /*
             * Inverse ADPCM if in prediction mode
             */
            if (s->prediction_mode[k][l]) {
                int n;
                for (m = 0; m < 8; m++) {
                    for (n = 1; n <= 4; n++)
                        if (m >= n)
                            subband_samples[k][l][m] +=
                                (adpcm_vb[s->prediction_vq[k][l]][n - 1] *
                                 subband_samples[k][l][m - n] / 8192);
                        else if (s->predictor_history)
                            subband_samples[k][l][m] +=
                                (adpcm_vb[s->prediction_vq[k][l]][n - 1] *
                                 s->subband_samples_hist[k][l][m - n + 4] / 8192);
                }
            }
        }

        /*
         * Decode VQ encoded high frequencies
         */
        for (l = s->vq_start_subband[k]; l < s->subband_activity[k]; l++) {
            /* 1 vector -> 32 samples but we only need the 8 samples
             * for this subsubframe. */
            int hfvq = s->high_freq_vq[k][l];

            if (!s->debug_flag & 0x01) {
                av_log(s->avctx, AV_LOG_DEBUG,
                       "Stream with high frequencies VQ coding\n");
                s->debug_flag |= 0x01;
            }

            int8x8_fmul_int32(subband_samples[k][l],
                              &high_freq_vq[hfvq][subsubframe * 8],
                              s->scale_factor[k][l][0]);
        }
    }

    /* Check for DSYNC after subsubframe */
    if (s->aspf || subsubframe == s->subsubframes[s->current_subframe] - 1) {
        if (0xFFFF == get_bits(&s->gb, 16)) {   /* 0xFFFF */
#ifdef TRACE
            av_log(s->avctx, AV_LOG_DEBUG, "Got subframe DSYNC\n");
#endif
        } else {
            av_log(s->avctx, AV_LOG_ERROR, "Didn't get subframe DSYNC\n");
        }
    }

    /* Backup predictor history for adpcm */
    for (k = base_channel; k < s->prim_channels; k++)
        for (l = 0; l < s->vq_start_subband[k]; l++)
            memcpy(s->subband_samples_hist[k][l],
                   &subband_samples[k][l][4],
                   4 * sizeof(subband_samples[0][0][0]));

    return 0;
}

static int dca_filter_channels(DCAContext *s, int block_index)
{
    float (*subband_samples)[DCA_SUBBANDS][8] = s->subband_samples[block_index];
    int k;

    /* 32 subbands QMF */
    for (k = 0; k < s->prim_channels; k++) {
/*        static float pcm_to_double[8] = { 32768.0, 32768.0, 524288.0, 524288.0,
                                            0, 8388608.0, 8388608.0 };*/
        qmf_32_subbands(s, k, subband_samples[k],
                        &s->samples[256 * s->channel_order_tab[k]],
                        M_SQRT1_2 * s->scale_bias /* pcm_to_double[s->source_pcm_res] */);
    }

    /* Down mixing */
    if (s->avctx->request_channels == 2 && s->prim_channels > 2) {
        dca_downmix(s->samples, s->amode, s->downmix_coef, s->channel_order_tab);
    }

    /* Generate LFE samples for this subsubframe FIXME!!! */
    if (s->output & DCA_LFE) {
        lfe_interpolation_fir(s, s->lfe, 2 * s->lfe,
                              s->lfe_data + 2 * s->lfe * (block_index + 4),
                              &s->samples[256 * dca_lfe_index[s->amode]],
                              (1.0 / 256.0) * s->scale_bias);
        /* Outputs 20bits pcm samples */
    }

    return 0;
}


static int dca_subframe_footer(DCAContext *s, int base_channel)
{
    int aux_data_count = 0, i;

    /*
     * Unpack optional information
     */

    /* presumably optional information only appears in the core? */
    if (!base_channel) {
        if (s->timestamp)
            skip_bits_long(&s->gb, 32);

        if (s->aux_data)
            aux_data_count = get_bits(&s->gb, 6);

        for (i = 0; i < aux_data_count; i++)
            get_bits(&s->gb, 8);

        if (s->crc_present && (s->downmix || s->dynrange))
            get_bits(&s->gb, 16);
    }

    return 0;
}

/**
 * Decode a dca frame block
 *
 * @param s     pointer to the DCAContext
 */

static int dca_decode_block(DCAContext *s, int base_channel, int block_index)
{
    int ret;

    /* Sanity check */
    if (s->current_subframe >= s->subframes) {
        av_log(s->avctx, AV_LOG_DEBUG, "check failed: %i>%i",
               s->current_subframe, s->subframes);
        return AVERROR_INVALIDDATA;
    }

    if (!s->current_subsubframe) {
#ifdef TRACE
        av_log(s->avctx, AV_LOG_DEBUG, "DSYNC dca_subframe_header\n");
#endif
        /* Read subframe header */
        if ((ret = dca_subframe_header(s, base_channel, block_index)))
            return ret;
    }

    /* Read subsubframe */
#ifdef TRACE
    av_log(s->avctx, AV_LOG_DEBUG, "DSYNC dca_subsubframe\n");
#endif
    if ((ret = dca_subsubframe(s, base_channel, block_index)))
        return ret;

    /* Update state */
    s->current_subsubframe++;
    if (s->current_subsubframe >= s->subsubframes[s->current_subframe]) {
        s->current_subsubframe = 0;
        s->current_subframe++;
    }
    if (s->current_subframe >= s->subframes) {
#ifdef TRACE
        av_log(s->avctx, AV_LOG_DEBUG, "DSYNC dca_subframe_footer\n");
#endif
        /* Read subframe footer */
        if ((ret = dca_subframe_footer(s, base_channel)))
            return ret;
    }

    return 0;
}

/**
 * Return the number of channels in an ExSS speaker mask (HD)
 */
static int dca_exss_mask2count(int mask)
{
    /* count bits that mean speaker pairs twice */
    return av_popcount(mask) +
           av_popcount(mask & (DCA_EXSS_CENTER_LEFT_RIGHT      |
                               DCA_EXSS_FRONT_LEFT_RIGHT       |
                               DCA_EXSS_FRONT_HIGH_LEFT_RIGHT  |
                               DCA_EXSS_WIDE_LEFT_RIGHT        |
                               DCA_EXSS_SIDE_LEFT_RIGHT        |
                               DCA_EXSS_SIDE_HIGH_LEFT_RIGHT   |
                               DCA_EXSS_SIDE_REAR_LEFT_RIGHT   |
                               DCA_EXSS_REAR_LEFT_RIGHT        |
                               DCA_EXSS_REAR_HIGH_LEFT_RIGHT));
}

/**
 * Skip mixing coefficients of a single mix out configuration (HD)
 */
static void dca_exss_skip_mix_coeffs(GetBitContext *gb, int channels, int out_ch)
{
    int i;

    for (i = 0; i < channels; i++) {
        int mix_map_mask = get_bits(gb, out_ch);
        int num_coeffs = av_popcount(mix_map_mask);
        skip_bits_long(gb, num_coeffs * 6);
    }
}

/**
 * Parse extension substream asset header (HD)
 */
static int dca_exss_parse_asset_header(DCAContext *s)
{
    int header_pos = get_bits_count(&s->gb);
    int header_size;
    int channels;
    int embedded_stereo = 0;
    int embedded_6ch    = 0;
    int drc_code_present;
    int extensions_mask;
    int i, j;

    if (get_bits_left(&s->gb) < 16)
        return -1;

    /* We will parse just enough to get to the extensions bitmask with which
     * we can set the profile value. */

    header_size = get_bits(&s->gb, 9) + 1;
    skip_bits(&s->gb, 3); // asset index

    if (s->static_fields) {
        if (get_bits1(&s->gb))
            skip_bits(&s->gb, 4); // asset type descriptor
        if (get_bits1(&s->gb))
            skip_bits_long(&s->gb, 24); // language descriptor

        if (get_bits1(&s->gb)) {
            /* How can one fit 1024 bytes of text here if the maximum value
             * for the asset header size field above was 512 bytes? */
            int text_length = get_bits(&s->gb, 10) + 1;
            if (get_bits_left(&s->gb) < text_length * 8)
                return -1;
            skip_bits_long(&s->gb, text_length * 8); // info text
        }

        skip_bits(&s->gb, 5); // bit resolution - 1
        skip_bits(&s->gb, 4); // max sample rate code
        channels = get_bits(&s->gb, 8) + 1;

        if (get_bits1(&s->gb)) { // 1-to-1 channels to speakers
            int spkr_remap_sets;
            int spkr_mask_size = 16;
            int num_spkrs[7];

            if (channels > 2)
                embedded_stereo = get_bits1(&s->gb);
            if (channels > 6)
                embedded_6ch = get_bits1(&s->gb);

            if (get_bits1(&s->gb)) {
                spkr_mask_size = (get_bits(&s->gb, 2) + 1) << 2;
                skip_bits(&s->gb, spkr_mask_size); // spkr activity mask
            }

            spkr_remap_sets = get_bits(&s->gb, 3);

            for (i = 0; i < spkr_remap_sets; i++) {
                /* std layout mask for each remap set */
                num_spkrs[i] = dca_exss_mask2count(get_bits(&s->gb, spkr_mask_size));
            }

            for (i = 0; i < spkr_remap_sets; i++) {
                int num_dec_ch_remaps = get_bits(&s->gb, 5) + 1;
                if (get_bits_left(&s->gb) < 0)
                    return -1;

                for (j = 0; j < num_spkrs[i]; j++) {
                    int remap_dec_ch_mask = get_bits_long(&s->gb, num_dec_ch_remaps);
                    int num_dec_ch = av_popcount(remap_dec_ch_mask);
                    skip_bits_long(&s->gb, num_dec_ch * 5); // remap codes
                }
            }

        } else {
            skip_bits(&s->gb, 3); // representation type
        }
    }

    drc_code_present = get_bits1(&s->gb);
    if (drc_code_present)
        get_bits(&s->gb, 8); // drc code

    if (get_bits1(&s->gb))
        skip_bits(&s->gb, 5); // dialog normalization code

    if (drc_code_present && embedded_stereo)
        get_bits(&s->gb, 8); // drc stereo code

    if (s->mix_metadata && get_bits1(&s->gb)) {
        skip_bits(&s->gb, 1); // external mix
        skip_bits(&s->gb, 6); // post mix gain code

        if (get_bits(&s->gb, 2) != 3) // mixer drc code
            skip_bits(&s->gb, 3); // drc limit
        else
            skip_bits(&s->gb, 8); // custom drc code

        if (get_bits1(&s->gb)) // channel specific scaling
            for (i = 0; i < s->num_mix_configs; i++)
                skip_bits_long(&s->gb, s->mix_config_num_ch[i] * 6); // scale codes
        else
            skip_bits_long(&s->gb, s->num_mix_configs * 6); // scale codes

        for (i = 0; i < s->num_mix_configs; i++) {
            if (get_bits_left(&s->gb) < 0)
                return -1;
            dca_exss_skip_mix_coeffs(&s->gb, channels, s->mix_config_num_ch[i]);
            if (embedded_6ch)
                dca_exss_skip_mix_coeffs(&s->gb, 6, s->mix_config_num_ch[i]);
            if (embedded_stereo)
                dca_exss_skip_mix_coeffs(&s->gb, 2, s->mix_config_num_ch[i]);
        }
    }

    switch (get_bits(&s->gb, 2)) {
    case 0: extensions_mask = get_bits(&s->gb, 12); break;
    case 1: extensions_mask = DCA_EXT_EXSS_XLL;     break;
    case 2: extensions_mask = DCA_EXT_EXSS_LBR;     break;
    case 3: extensions_mask = 0; /* aux coding */   break;
    }

    /* not parsed further, we were only interested in the extensions mask */

    if (get_bits_left(&s->gb) < 0)
        return -1;

    if (get_bits_count(&s->gb) - header_pos > header_size * 8) {
        av_log(s->avctx, AV_LOG_WARNING, "Asset header size mismatch.\n");
        return -1;
    }
    skip_bits_long(&s->gb, header_pos + header_size * 8 - get_bits_count(&s->gb));

    if (extensions_mask & DCA_EXT_EXSS_XLL)
        s->profile = FF_PROFILE_DTS_HD_MA;
    else if (extensions_mask & (DCA_EXT_EXSS_XBR | DCA_EXT_EXSS_X96 |
                                DCA_EXT_EXSS_XXCH))
        s->profile = FF_PROFILE_DTS_HD_HRA;

    if (!(extensions_mask & DCA_EXT_CORE))
        av_log(s->avctx, AV_LOG_WARNING, "DTS core detection mismatch.\n");
    if ((extensions_mask & DCA_CORE_EXTS) != s->core_ext_mask)
        av_log(s->avctx, AV_LOG_WARNING,
               "DTS extensions detection mismatch (%d, %d)\n",
               extensions_mask & DCA_CORE_EXTS, s->core_ext_mask);

    return 0;
}

/**
 * Parse extension substream header (HD)
 */
static void dca_exss_parse_header(DCAContext *s)
{
    int ss_index;
    int blownup;
    int num_audiop = 1;
    int num_assets = 1;
    int active_ss_mask[8];
    int i, j;

    if (get_bits_left(&s->gb) < 52)
        return;

    skip_bits(&s->gb, 8); // user data
    ss_index = get_bits(&s->gb, 2);

    blownup = get_bits1(&s->gb);
    skip_bits(&s->gb,  8 + 4 * blownup); // header_size
    skip_bits(&s->gb, 16 + 4 * blownup); // hd_size

    s->static_fields = get_bits1(&s->gb);
    if (s->static_fields) {
        skip_bits(&s->gb, 2); // reference clock code
        skip_bits(&s->gb, 3); // frame duration code

        if (get_bits1(&s->gb))
            skip_bits_long(&s->gb, 36); // timestamp

        /* a single stream can contain multiple audio assets that can be
         * combined to form multiple audio presentations */

        num_audiop = get_bits(&s->gb, 3) + 1;
        if (num_audiop > 1) {
            av_log_ask_for_sample(s->avctx, "Multiple DTS-HD audio presentations.");
            /* ignore such streams for now */
            return;
        }

        num_assets = get_bits(&s->gb, 3) + 1;
        if (num_assets > 1) {
            av_log_ask_for_sample(s->avctx, "Multiple DTS-HD audio assets.");
            /* ignore such streams for now */
            return;
        }

        for (i = 0; i < num_audiop; i++)
            active_ss_mask[i] = get_bits(&s->gb, ss_index + 1);

        for (i = 0; i < num_audiop; i++)
            for (j = 0; j <= ss_index; j++)
                if (active_ss_mask[i] & (1 << j))
                    skip_bits(&s->gb, 8); // active asset mask

        s->mix_metadata = get_bits1(&s->gb);
        if (s->mix_metadata) {
            int mix_out_mask_size;

            skip_bits(&s->gb, 2); // adjustment level
            mix_out_mask_size  = (get_bits(&s->gb, 2) + 1) << 2;
            s->num_mix_configs =  get_bits(&s->gb, 2) + 1;

            for (i = 0; i < s->num_mix_configs; i++) {
                int mix_out_mask        = get_bits(&s->gb, mix_out_mask_size);
                s->mix_config_num_ch[i] = dca_exss_mask2count(mix_out_mask);
            }
        }
    }

    for (i = 0; i < num_assets; i++)
        skip_bits_long(&s->gb, 16 + 4 * blownup);  // asset size

    for (i = 0; i < num_assets; i++) {
        if (dca_exss_parse_asset_header(s))
            return;
    }

    /* not parsed further, we were only interested in the extensions mask
     * from the asset header */
}

/**
 * Main frame decoding function
 * FIXME add arguments
 */
static int dca_decode_frame(AVCodecContext *avctx, void *data,
                            int *got_frame_ptr, AVPacket *avpkt)
{
    const uint8_t *buf = avpkt->data;
    int buf_size = avpkt->size;

    int lfe_samples;
    int num_core_channels = 0;
    int i, ret;
    float   *samples_flt;
    int16_t *samples_s16;
    DCAContext *s = avctx->priv_data;
    int channels;
    int core_ss_end;


    s->xch_present = 0;

    s->dca_buffer_size = ff_dca_convert_bitstream(buf, buf_size, s->dca_buffer,
                                                  DCA_MAX_FRAME_SIZE + DCA_MAX_EXSS_HEADER_SIZE);
    if (s->dca_buffer_size == AVERROR_INVALIDDATA) {
        av_log(avctx, AV_LOG_ERROR, "Not a valid DCA frame\n");
        return AVERROR_INVALIDDATA;
    }

    init_get_bits(&s->gb, s->dca_buffer, s->dca_buffer_size * 8);
    if ((ret = dca_parse_frame_header(s)) < 0) {
        //seems like the frame is corrupt, try with the next one
        return ret;
    }
    //set AVCodec values with parsed data
    avctx->sample_rate = s->sample_rate;
    avctx->bit_rate    = s->bit_rate;

    s->profile = FF_PROFILE_DTS;

    for (i = 0; i < (s->sample_blocks / 8); i++) {
        if ((ret = dca_decode_block(s, 0, i))) {
            av_log(avctx, AV_LOG_ERROR, "error decoding block\n");
            return ret;
        }
    }

    /* record number of core channels incase less than max channels are requested */
    num_core_channels = s->prim_channels;

    if (s->ext_coding)
        s->core_ext_mask = dca_ext_audio_descr_mask[s->ext_descr];
    else
        s->core_ext_mask = 0;

    core_ss_end = FFMIN(s->frame_size, s->dca_buffer_size) * 8;

    /* only scan for extensions if ext_descr was unknown or indicated a
     * supported XCh extension */
    if (s->core_ext_mask < 0 || s->core_ext_mask & DCA_EXT_XCH) {

        /* if ext_descr was unknown, clear s->core_ext_mask so that the
         * extensions scan can fill it up */
        s->core_ext_mask = FFMAX(s->core_ext_mask, 0);

        /* extensions start at 32-bit boundaries into bitstream */
        skip_bits_long(&s->gb, (-get_bits_count(&s->gb)) & 31);

        while (core_ss_end - get_bits_count(&s->gb) >= 32) {
            uint32_t bits = get_bits_long(&s->gb, 32);

            switch (bits) {
            case 0x5a5a5a5a: {
                int ext_amode, xch_fsize;

                s->xch_base_channel = s->prim_channels;

                /* validate sync word using XCHFSIZE field */
                xch_fsize = show_bits(&s->gb, 10);
                if ((s->frame_size != (get_bits_count(&s->gb) >> 3) - 4 + xch_fsize) &&
                    (s->frame_size != (get_bits_count(&s->gb) >> 3) - 4 + xch_fsize + 1))
                    continue;

                /* skip length-to-end-of-frame field for the moment */
                skip_bits(&s->gb, 10);

                s->core_ext_mask |= DCA_EXT_XCH;

                /* extension amode(number of channels in extension) should be 1 */
                /* AFAIK XCh is not used for more channels */
                if ((ext_amode = get_bits(&s->gb, 4)) != 1) {
                    av_log(avctx, AV_LOG_ERROR, "XCh extension amode %d not"
                           " supported!\n", ext_amode);
                    continue;
                }

                /* much like core primary audio coding header */
                dca_parse_audio_coding_header(s, s->xch_base_channel);

                for (i = 0; i < (s->sample_blocks / 8); i++)
                    if ((ret = dca_decode_block(s, s->xch_base_channel, i))) {
                        av_log(avctx, AV_LOG_ERROR, "error decoding XCh extension\n");
                        continue;
                    }

                s->xch_present = 1;
                break;
            }
            case 0x47004a03:
                /* XXCh: extended channels */
                /* usually found either in core or HD part in DTS-HD HRA streams,
                 * but not in DTS-ES which contains XCh extensions instead */
                s->core_ext_mask |= DCA_EXT_XXCH;
                break;

            case 0x1d95f262: {
                int fsize96 = show_bits(&s->gb, 12) + 1;
                if (s->frame_size != (get_bits_count(&s->gb) >> 3) - 4 + fsize96)
                    continue;

                av_log(avctx, AV_LOG_DEBUG, "X96 extension found at %d bits\n",
                       get_bits_count(&s->gb));
                skip_bits(&s->gb, 12);
                av_log(avctx, AV_LOG_DEBUG, "FSIZE96 = %d bytes\n", fsize96);
                av_log(avctx, AV_LOG_DEBUG, "REVNO = %d\n", get_bits(&s->gb, 4));

                s->core_ext_mask |= DCA_EXT_X96;
                break;
            }
            }

            skip_bits_long(&s->gb, (-get_bits_count(&s->gb)) & 31);
        }
    } else {
        /* no supported extensions, skip the rest of the core substream */
        skip_bits_long(&s->gb, core_ss_end - get_bits_count(&s->gb));
    }

    if (s->core_ext_mask & DCA_EXT_X96)
        s->profile = FF_PROFILE_DTS_96_24;
    else if (s->core_ext_mask & (DCA_EXT_XCH | DCA_EXT_XXCH))
        s->profile = FF_PROFILE_DTS_ES;

    /* check for ExSS (HD part) */
    if (s->dca_buffer_size - s->frame_size > 32 &&
        get_bits_long(&s->gb, 32) == DCA_HD_MARKER)
        dca_exss_parse_header(s);

    avctx->profile = s->profile;

    channels = s->prim_channels + !!s->lfe;

    if (s->amode < 16) {
        avctx->channel_layout = dca_core_channel_layout[s->amode];

        if (s->xch_present && (!avctx->request_channels ||
                               avctx->request_channels > num_core_channels + !!s->lfe)) {
            avctx->channel_layout |= AV_CH_BACK_CENTER;
            if (s->lfe) {
                avctx->channel_layout |= AV_CH_LOW_FREQUENCY;
                s->channel_order_tab = dca_channel_reorder_lfe_xch[s->amode];
            } else {
                s->channel_order_tab = dca_channel_reorder_nolfe_xch[s->amode];
            }
        } else {
            channels = num_core_channels + !!s->lfe;
            s->xch_present = 0; /* disable further xch processing */
            if (s->lfe) {
                avctx->channel_layout |= AV_CH_LOW_FREQUENCY;
                s->channel_order_tab = dca_channel_reorder_lfe[s->amode];
            } else
                s->channel_order_tab = dca_channel_reorder_nolfe[s->amode];
        }

        if (channels > !!s->lfe &&
            s->channel_order_tab[channels - 1 - !!s->lfe] < 0)
            return AVERROR_INVALIDDATA;

        if (avctx->request_channels == 2 && s->prim_channels > 2) {
            channels = 2;
            s->output = DCA_STEREO;
            avctx->channel_layout = AV_CH_LAYOUT_STEREO;
        }
    } else {
        av_log(avctx, AV_LOG_ERROR, "Non standard configuration %d !\n", s->amode);
        return AVERROR_INVALIDDATA;
    }


    /* There is nothing that prevents a dts frame to change channel configuration
       but Libav doesn't support that so only set the channels if it is previously
       unset. Ideally during the first probe for channels the crc should be checked
       and only set avctx->channels when the crc is ok. Right now the decoder could
       set the channels based on a broken first frame.*/
    if (s->is_channels_set == 0) {
        s->is_channels_set = 1;
        avctx->channels = channels;
    }
    if (avctx->channels != channels) {
        av_log(avctx, AV_LOG_ERROR, "DCA decoder does not support number of "
               "channels changing in stream. Skipping frame.\n");
        return AVERROR_PATCHWELCOME;
    }

    /* get output buffer */
    s->frame.nb_samples = 256 * (s->sample_blocks / 8);
    if ((ret = avctx->get_buffer(avctx, &s->frame)) < 0) {
        av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
        return ret;
    }
    samples_flt = (float *)   s->frame.data[0];
    samples_s16 = (int16_t *) s->frame.data[0];

    /* filter to get final output */
    for (i = 0; i < (s->sample_blocks / 8); i++) {
        dca_filter_channels(s, i);

        /* If this was marked as a DTS-ES stream we need to subtract back- */
        /* channel from SL & SR to remove matrixed back-channel signal */
        if ((s->source_pcm_res & 1) && s->xch_present) {
            float *back_chan = s->samples + s->channel_order_tab[s->xch_base_channel]     * 256;
            float *lt_chan   = s->samples + s->channel_order_tab[s->xch_base_channel - 2] * 256;
            float *rt_chan   = s->samples + s->channel_order_tab[s->xch_base_channel - 1] * 256;
            s->fdsp.vector_fmac_scalar(lt_chan, back_chan, -M_SQRT1_2, 256);
            s->fdsp.vector_fmac_scalar(rt_chan, back_chan, -M_SQRT1_2, 256);
        }

        if (avctx->sample_fmt == AV_SAMPLE_FMT_FLT) {
            s->fmt_conv.float_interleave(samples_flt, s->samples_chanptr, 256,
                                         channels);
            samples_flt += 256 * channels;
        } else {
            s->fmt_conv.float_to_int16_interleave(samples_s16,
                                                  s->samples_chanptr, 256,
                                                  channels);
            samples_s16 += 256 * channels;
        }
    }

    /* update lfe history */
    lfe_samples = 2 * s->lfe * (s->sample_blocks / 8);
    for (i = 0; i < 2 * s->lfe * 4; i++)
        s->lfe_data[i] = s->lfe_data[i + lfe_samples];

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

    return buf_size;
}



/**
 * DCA initialization
 *
 * @param avctx     pointer to the AVCodecContext
 */

static av_cold int dca_decode_init(AVCodecContext *avctx)
{
    DCAContext *s = avctx->priv_data;
    int i;

    s->avctx = avctx;
    dca_init_vlcs();

    avpriv_float_dsp_init(&s->fdsp, avctx->flags & CODEC_FLAG_BITEXACT);
    ff_mdct_init(&s->imdct, 6, 1, 1.0);
    ff_synth_filter_init(&s->synth);
    ff_dcadsp_init(&s->dcadsp);
    ff_fmt_convert_init(&s->fmt_conv, avctx);

    for (i = 0; i < DCA_PRIM_CHANNELS_MAX + 1; i++)
        s->samples_chanptr[i] = s->samples + i * 256;

    if (avctx->request_sample_fmt == AV_SAMPLE_FMT_FLT) {
        avctx->sample_fmt = AV_SAMPLE_FMT_FLT;
        s->scale_bias     = 1.0 / 32768.0;
    } else {
        avctx->sample_fmt = AV_SAMPLE_FMT_S16;
        s->scale_bias     = 1.0;
    }

    /* allow downmixing to stereo */
    if (avctx->channels > 0 && avctx->request_channels < avctx->channels &&
        avctx->request_channels == 2) {
        avctx->channels = avctx->request_channels;
    }

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

    return 0;
}

static av_cold int dca_decode_end(AVCodecContext *avctx)
{
    DCAContext *s = avctx->priv_data;
    ff_mdct_end(&s->imdct);
    return 0;
}

static const AVProfile profiles[] = {
    { FF_PROFILE_DTS,        "DTS"        },
    { FF_PROFILE_DTS_ES,     "DTS-ES"     },
    { FF_PROFILE_DTS_96_24,  "DTS 96/24"  },
    { FF_PROFILE_DTS_HD_HRA, "DTS-HD HRA" },
    { FF_PROFILE_DTS_HD_MA,  "DTS-HD MA"  },
    { FF_PROFILE_UNKNOWN },
};

AVCodec ff_dca_decoder = {
    .name            = "dca",
    .type            = AVMEDIA_TYPE_AUDIO,
    .id              = AV_CODEC_ID_DTS,
    .priv_data_size  = sizeof(DCAContext),
    .init            = dca_decode_init,
    .decode          = dca_decode_frame,
    .close           = dca_decode_end,
    .long_name       = NULL_IF_CONFIG_SMALL("DCA (DTS Coherent Acoustics)"),
    .capabilities    = CODEC_CAP_CHANNEL_CONF | CODEC_CAP_DR1,
    .sample_fmts     = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_FLT,
                                                       AV_SAMPLE_FMT_S16,
                                                       AV_SAMPLE_FMT_NONE },
    .profiles        = NULL_IF_CONFIG_SMALL(profiles),
};