libavcodec/dcadec.c

/* [<][>][^][v][top][bottom][index][help] */
This source file includes following definitions.
get_bitalloc
dca_init_vlcs
get_array
dca_xxch2index
dca_parse_audio_coding_header
dca_parse_frame_header
get_scale
dca_subframe_header
qmf_32_subbands
lfe_interpolation_fir
dca_downmix
decode_blockcode
decode_blockcodes
dca_subsubframe
dca_filter_channels
dca_subframe_footer
dca_decode_block
ff_dca_xbr_parse_frame
ff_dca_xxch_decode_frame
dca_dmix_code
dca_decode_frame
dca_decode_init
dca_decode_end
/*
 * 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 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
 */

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

#include "libavutil/channel_layout.h"
#include "libavutil/common.h"
#include "libavutil/float_dsp.h"
#include "libavutil/internal.h"
#include "libavutil/intreadwrite.h"
#include "libavutil/mathematics.h"
#include "libavutil/opt.h"
#include "libavutil/samplefmt.h"

#include "avcodec.h"
#include "dca.h"
#include "dca_syncwords.h"
#include "dcadata.h"
#include "dcadsp.h"
#include "dcahuff.h"
#include "fft.h"
#include "fmtconvert.h"
#include "get_bits.h"
#include "internal.h"
#include "mathops.h"
#include "synth_filter.h"

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

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
};


enum DCAXxchSpeakerMask {
    DCA_XXCH_FRONT_CENTER          = 0x0000001,
    DCA_XXCH_FRONT_LEFT            = 0x0000002,
    DCA_XXCH_FRONT_RIGHT           = 0x0000004,
    DCA_XXCH_SIDE_REAR_LEFT        = 0x0000008,
    DCA_XXCH_SIDE_REAR_RIGHT       = 0x0000010,
    DCA_XXCH_LFE1                  = 0x0000020,
    DCA_XXCH_REAR_CENTER           = 0x0000040,
    DCA_XXCH_SURROUND_REAR_LEFT    = 0x0000080,
    DCA_XXCH_SURROUND_REAR_RIGHT   = 0x0000100,
    DCA_XXCH_SIDE_SURROUND_LEFT    = 0x0000200,
    DCA_XXCH_SIDE_SURROUND_RIGHT   = 0x0000400,
    DCA_XXCH_FRONT_CENTER_LEFT     = 0x0000800,
    DCA_XXCH_FRONT_CENTER_RIGHT    = 0x0001000,
    DCA_XXCH_FRONT_HIGH_LEFT       = 0x0002000,
    DCA_XXCH_FRONT_HIGH_CENTER     = 0x0004000,
    DCA_XXCH_FRONT_HIGH_RIGHT      = 0x0008000,
    DCA_XXCH_LFE2                  = 0x0010000,
    DCA_XXCH_SIDE_FRONT_LEFT       = 0x0020000,
    DCA_XXCH_SIDE_FRONT_RIGHT      = 0x0040000,
    DCA_XXCH_OVERHEAD              = 0x0080000,
    DCA_XXCH_SIDE_HIGH_LEFT        = 0x0100000,
    DCA_XXCH_SIDE_HIGH_RIGHT       = 0x0200000,
    DCA_XXCH_REAR_HIGH_CENTER      = 0x0400000,
    DCA_XXCH_REAR_HIGH_LEFT        = 0x0800000,
    DCA_XXCH_REAR_HIGH_RIGHT       = 0x1000000,
    DCA_XXCH_REAR_LOW_CENTER       = 0x2000000,
    DCA_XXCH_REAR_LOW_LEFT         = 0x4000000,
    DCA_XXCH_REAR_LOW_RIGHT        = 0x8000000,
};

#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_NSYNCAUX        0x9A1105A0


/** Bit allocation */
typedef struct BitAlloc {
    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;
}

static float dca_dmix_code(unsigned code);

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[ff_dca_vlc_offs[i]];
        dca_bitalloc_index.vlc[i].table_allocated = ff_dca_vlc_offs[i + 1] - ff_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[ff_dca_vlc_offs[i + 5]];
        dca_scalefactor.vlc[i].table_allocated = ff_dca_vlc_offs[i + 6] - ff_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[ff_dca_vlc_offs[i + 10]];
        dca_tmode.vlc[i].table_allocated = ff_dca_vlc_offs[i + 11] - ff_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[ff_dca_vlc_offs[c]];
            dca_smpl_bitalloc[i + 1].vlc[j].table_allocated = ff_dca_vlc_offs[c + 1] - ff_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 inline int dca_xxch2index(DCAContext *s, int xxch_ch)
{
    int i, base, mask;

    /* locate channel set containing the channel */
    for (i = -1, base = 0, mask = (s->xxch_core_spkmask & ~DCA_XXCH_LFE1);
         i <= s->xxch_chset && !(mask & xxch_ch); mask = s->xxch_spk_masks[++i])
        base += av_popcount(mask);

    return base + av_popcount(mask & (xxch_ch - 1));
}

static int dca_parse_audio_coding_header(DCAContext *s, int base_channel,
                                         int xxch)
{
    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 };
    int hdr_pos = 0, hdr_size = 0;
    float scale_factor;
    int this_chans, acc_mask;
    int embedded_downmix;
    int nchans, mask[8];
    int coeff, ichan;

    /* xxch has arbitrary sized audio coding headers */
    if (xxch) {
        hdr_pos  = get_bits_count(&s->gb);
        hdr_size = get_bits(&s->gb, 7) + 1;
    }

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

    /* obtain speaker layout mask & downmix coefficients for XXCH */
    if (xxch) {
        acc_mask = s->xxch_core_spkmask;

        this_chans = get_bits(&s->gb, s->xxch_nbits_spk_mask - 6) << 6;
        s->xxch_spk_masks[s->xxch_chset] = this_chans;
        s->xxch_chset_nch[s->xxch_chset] = nchans;

        for (i = 0; i <= s->xxch_chset; i++)
            acc_mask |= s->xxch_spk_masks[i];

        /* check for downmixing information */
        if (get_bits1(&s->gb)) {
            embedded_downmix = get_bits1(&s->gb);
            coeff            = get_bits(&s->gb, 6);

            if (coeff<1 || coeff>61) {
                av_log(s->avctx, AV_LOG_ERROR, "6bit coeff %d is out of range\n", coeff);
                return AVERROR_INVALIDDATA;
            }

            scale_factor     = -1.0f / dca_dmix_code((coeff<<2)-3);

            s->xxch_dmix_sf[s->xxch_chset] = scale_factor;

            for (i = base_channel; i < s->prim_channels; i++) {
                mask[i] = get_bits(&s->gb, s->xxch_nbits_spk_mask);
            }

            for (j = base_channel; j < s->prim_channels; j++) {
                memset(s->xxch_dmix_coeff[j], 0, sizeof(s->xxch_dmix_coeff[0]));
                s->xxch_dmix_embedded |= (embedded_downmix << j);
                for (i = 0; i < s->xxch_nbits_spk_mask; i++) {
                    if (mask[j] & (1 << i)) {
                        if ((1 << i) == DCA_XXCH_LFE1) {
                            av_log(s->avctx, AV_LOG_WARNING,
                                   "DCA-XXCH: dmix to LFE1 not supported.\n");
                            continue;
                        }

                        coeff = get_bits(&s->gb, 7);
                        ichan = dca_xxch2index(s, 1 << i);
                        if ((coeff&63)<1 || (coeff&63)>61) {
                            av_log(s->avctx, AV_LOG_ERROR, "7bit coeff %d is out of range\n", coeff);
                            return AVERROR_INVALIDDATA;
                        }
                        s->xxch_dmix_coeff[j][ichan] = dca_dmix_code((coeff<<2)-3);
                    }
                }
            }
        }
    }

    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 (!xxch) {
        if (s->crc_present) {
            /* Audio header CRC check */
            get_bits(&s->gb, 16);
        }
    } else {
        /* Skip to the end of the header, also ignore CRC if present  */
        i = get_bits_count(&s->gb);
        if (hdr_pos + 8 * hdr_size > i)
            skip_bits_long(&s->gb, hdr_pos + 8 * hdr_size - i);
    }

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

    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          = ff_dca_bit_rates[s->bit_rate_index];
    if (!s->bit_rate)
        return AVERROR_INVALIDDATA;

    skip_bits1(&s->gb); // always 0 (reserved, cf. ETSI TS 102 114 V1.4.1)
    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);

    if (s->lfe > 2) {
        s->lfe = 0;
        av_log(s->avctx, AV_LOG_ERROR, "Invalid LFE value: %d\n", s->lfe);
        return AVERROR_INVALIDDATA;
    }

    /* 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;

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

    return dca_parse_audio_coding_header(s, 0, 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_dlog(s->avctx, "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 = ff_dca_scale_factor_quant7;
            log_size    = 7;
        } else {
            scale_table = ff_dca_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;
            }
        }
    }

    /* 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) {
        int quant7;
        /* 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 */
        quant7 = get_bits(&s->gb, 8);
        if (quant7 > 127) {
            avpriv_request_sample(s->avctx, "LFEScaleIndex larger than 127");
            return AVERROR_INVALIDDATA;
        }
        s->lfe_scale_factor = ff_dca_scale_factor_quant7[quant7];

        /* 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;
    }

    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 sb_act = s->subband_activity[chans];

    scale *= sqrt(1 / 8.0);

    /* Select filter */
    if (!s->multirate_inter)    /* Non-perfect reconstruction */
        prCoeff = ff_dca_fir_32bands_nonperfect;
    else                        /* Perfect reconstruction */
        prCoeff = ff_dca_fir_32bands_perfect;

    s->dcadsp.qmf_32_subbands(samples_in, sb_act, &s->synth, &s->imdct,
                              s->subband_fir_hist[chans],
                              &s->hist_index[chans],
                              s->subband_fir_noidea[chans], prCoeff,
                              samples_out, s->raXin, scale);
}

static void lfe_interpolation_fir(DCAContext *s, int decimation_select,
                                  int num_deci_sample, float *samples_in,
                                  float *samples_out)
{
    /* 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 idx;
    const float *prCoeff;
    int deciindex;

    /* Select decimation filter */
    if (decimation_select == 1) {
        idx     = 1;
        prCoeff = ff_dca_lfe_fir_128;
    } else {
        idx     = 0;
        prCoeff = ff_dca_lfe_fir_64;
    }
    /* Interpolation */
    for (deciindex = 0; deciindex < num_deci_sample; deciindex++) {
        s->dcadsp.lfe_fir[idx](samples_out, samples_in, prCoeff);
        samples_in++;
        samples_out += 2 * 32 * (1 + idx);
    }
}

/* downmixing routines */
#define MIX_REAR1(samples, s1, rs, coef)            \
    samples[0][i] += samples[s1][i] * coef[rs][0];  \
    samples[1][i] += samples[s1][i] * coef[rs][1];

#define MIX_REAR2(samples, s1, s2, rs, coef)                                          \
    samples[0][i] += samples[s1][i] * coef[rs][0] + samples[s2][i] * coef[rs + 1][0]; \
    samples[1][i] += samples[s1][i] * coef[rs][1] + samples[s2][i] * coef[rs + 1][1];

#define MIX_FRONT3(samples, coef)                                      \
    t = samples[c][i];                                                 \
    u = samples[l][i];                                                 \
    v = samples[r][i];                                                 \
    samples[0][i] = t * coef[0][0] + u * coef[1][0] + v * coef[2][0];  \
    samples[1][i] = 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 lfe_present,
                        float coef[DCA_PRIM_CHANNELS_MAX + 1][2],
                        const int8_t *channel_mapping)
{
    int c, l, r, sl, sr, s;
    int i;
    float t, u, v;

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

#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, int32_t *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, int32_t *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 };

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(int32_t, block, [8 * DCA_SUBBANDS]);

    /*
     * Audio data
     */

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

    for (k = base_channel; k < s->prim_channels; k++) {
        float rscale[DCA_SUBBANDS];

        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) {
                rscale[l] = 0;
                memset(block + 8 * l, 0, 8 * sizeof(block[0]));
            } else {
                /* Deal with transients */
                int sfi = s->transition_mode[k][l] && subsubframe >= s->transition_mode[k][l];
                rscale[l] = 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 + 8 * l);
                        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[8 * l + m] = get_sbits(&s->gb, abits - 3);
                    }
                } else {
                    /* Huffman coded */
                    for (m = 0; m < 8; m++)
                        block[8 * l + m] = get_bitalloc(&s->gb,
                                                        &dca_smpl_bitalloc[abits], sel);
                }
            }
        }

        s->fmt_conv.int32_to_float_fmul_array8(&s->fmt_conv, subband_samples[k][0],
                                               block, rscale, 8 * s->vq_start_subband[k]);

        for (l = 0; l < s->vq_start_subband[k]; l++) {
            int m;
            /*
             * Inverse ADPCM if in prediction mode
             */
            if (s->prediction_mode[k][l]) {
                int n;
                if (s->predictor_history)
                    subband_samples[k][l][0] += (ff_dca_adpcm_vb[s->prediction_vq[k][l]][0] *
                                                 s->subband_samples_hist[k][l][3] +
                                                 ff_dca_adpcm_vb[s->prediction_vq[k][l]][1] *
                                                 s->subband_samples_hist[k][l][2] +
                                                 ff_dca_adpcm_vb[s->prediction_vq[k][l]][2] *
                                                 s->subband_samples_hist[k][l][1] +
                                                 ff_dca_adpcm_vb[s->prediction_vq[k][l]][3] *
                                                 s->subband_samples_hist[k][l][0]) *
                                                (1.0f / 8192);
                for (m = 1; m < 8; m++) {
                    float sum = ff_dca_adpcm_vb[s->prediction_vq[k][l]][0] *
                                subband_samples[k][l][m - 1];
                    for (n = 2; n <= 4; n++)
                        if (m >= n)
                            sum += ff_dca_adpcm_vb[s->prediction_vq[k][l]][n - 1] *
                                   subband_samples[k][l][m - n];
                        else if (s->predictor_history)
                            sum += ff_dca_adpcm_vb[s->prediction_vq[k][l]][n - 1] *
                                   s->subband_samples_hist[k][l][m - n + 4];
                    subband_samples[k][l][m] += sum * (1.0f / 8192);
                }
            }
        }

        /*
         * Decode VQ encoded high frequencies
         */
        if (s->subband_activity[k] > s->vq_start_subband[k]) {
            if (!(s->debug_flag & 0x01)) {
                av_log(s->avctx, AV_LOG_DEBUG,
                       "Stream with high frequencies VQ coding\n");
                s->debug_flag |= 0x01;
            }
            s->dcadsp.decode_hf(subband_samples[k], s->high_freq_vq[k],
                                ff_dca_high_freq_vq, subsubframe * 8,
                                s->scale_factor[k], s->vq_start_subband[k],
                                s->subband_activity[k]);
        }
    }

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

    /* Backup predictor history for adpcm */
    for (k = base_channel; k < s->prim_channels; k++)
        for (l = 0; l < s->vq_start_subband[k]; l++)
            AV_COPY128(s->subband_samples_hist[k][l], &subband_samples[k][l][4]);

    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++) {
        if (s->channel_order_tab[k] >= 0)
            qmf_32_subbands(s, k, subband_samples[k],
                            s->samples_chanptr[s->channel_order_tab[k]],
                            M_SQRT1_2 / 32768.0);
    }

    /* Generate LFE samples for this subsubframe FIXME!!! */
    if (s->lfe) {
        lfe_interpolation_fir(s, s->lfe, 2 * s->lfe,
                              s->lfe_data + 2 * s->lfe * (block_index + 4),
                              s->samples_chanptr[s->lfe_index]);
        /* Outputs 20bits pcm samples */
    }

    /* Downmixing to Stereo */
    if (s->prim_channels + !!s->lfe > 2 &&
        s->avctx->request_channel_layout == AV_CH_LAYOUT_STEREO) {
        dca_downmix(s->samples_chanptr, s->amode, !!s->lfe, s->downmix_coef,
                    s->channel_order_tab);
    }

    return 0;
}

static int dca_subframe_footer(DCAContext *s, int base_channel)
{
    int in, out, aux_data_count, aux_data_end, reserved;
    uint32_t nsyncaux;

    /*
     * 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);

            // align (32-bit)
            skip_bits_long(&s->gb, (-get_bits_count(&s->gb)) & 31);

            aux_data_end = 8 * aux_data_count + get_bits_count(&s->gb);

            if ((nsyncaux = get_bits_long(&s->gb, 32)) != DCA_NSYNCAUX) {
                av_log(s->avctx, AV_LOG_ERROR, "nSYNCAUX mismatch %#"PRIx32"\n",
                       nsyncaux);
                return AVERROR_INVALIDDATA;
            }

            if (get_bits1(&s->gb)) { // bAUXTimeStampFlag
                avpriv_request_sample(s->avctx,
                                      "Auxiliary Decode Time Stamp Flag");
                // align (4-bit)
                skip_bits(&s->gb, (-get_bits_count(&s->gb)) & 4);
                // 44 bits: nMSByte (8), nMarker (4), nLSByte (28), nMarker (4)
                skip_bits_long(&s->gb, 44);
            }

            if ((s->core_downmix = get_bits1(&s->gb))) {
                int am = get_bits(&s->gb, 3);
                switch (am) {
                case 0:
                    s->core_downmix_amode = DCA_MONO;
                    break;
                case 1:
                    s->core_downmix_amode = DCA_STEREO;
                    break;
                case 2:
                    s->core_downmix_amode = DCA_STEREO_TOTAL;
                    break;
                case 3:
                    s->core_downmix_amode = DCA_3F;
                    break;
                case 4:
                    s->core_downmix_amode = DCA_2F1R;
                    break;
                case 5:
                    s->core_downmix_amode = DCA_2F2R;
                    break;
                case 6:
                    s->core_downmix_amode = DCA_3F1R;
                    break;
                default:
                    av_log(s->avctx, AV_LOG_ERROR,
                           "Invalid mode %d for embedded downmix coefficients\n",
                           am);
                    return AVERROR_INVALIDDATA;
                }
                for (out = 0; out < ff_dca_channels[s->core_downmix_amode]; out++) {
                    for (in = 0; in < s->prim_channels + !!s->lfe; in++) {
                        uint16_t tmp = get_bits(&s->gb, 9);
                        if ((tmp & 0xFF) > 241) {
                            av_log(s->avctx, AV_LOG_ERROR,
                                   "Invalid downmix coefficient code %"PRIu16"\n",
                                   tmp);
                            return AVERROR_INVALIDDATA;
                        }
                        s->core_downmix_codes[in][out] = tmp;
                    }
                }
            }

            align_get_bits(&s->gb); // byte align
            skip_bits(&s->gb, 16);  // nAUXCRC16

            // additional data (reserved, cf. ETSI TS 102 114 V1.4.1)
            if ((reserved = (aux_data_end - get_bits_count(&s->gb))) < 0) {
                av_log(s->avctx, AV_LOG_ERROR,
                       "Overread auxiliary data by %d bits\n", -reserved);
                return AVERROR_INVALIDDATA;
            } else if (reserved) {
                avpriv_request_sample(s->avctx,
                                      "Core auxiliary data reserved content");
                skip_bits_long(&s->gb, reserved);
            }
        }

        if (s->crc_present && 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) {
        /* Read subframe header */
        if ((ret = dca_subframe_header(s, base_channel, block_index)))
            return ret;
    }

    /* Read subsubframe */
    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) {
        /* Read subframe footer */
        if ((ret = dca_subframe_footer(s, base_channel)))
            return ret;
    }

    return 0;
}

int ff_dca_xbr_parse_frame(DCAContext *s)
{
    int scale_table_high[DCA_CHSET_CHANS_MAX][DCA_SUBBANDS][2];
    int active_bands[DCA_CHSETS_MAX][DCA_CHSET_CHANS_MAX];
    int abits_high[DCA_CHSET_CHANS_MAX][DCA_SUBBANDS];
    int anctemp[DCA_CHSET_CHANS_MAX];
    int chset_fsize[DCA_CHSETS_MAX];
    int n_xbr_ch[DCA_CHSETS_MAX];
    int hdr_size, num_chsets, xbr_tmode, hdr_pos;
    int i, j, k, l, chset, chan_base;

    av_log(s->avctx, AV_LOG_DEBUG, "DTS-XBR: decoding XBR extension\n");

    /* get bit position of sync header */
    hdr_pos = get_bits_count(&s->gb) - 32;

    hdr_size = get_bits(&s->gb, 6) + 1;
    num_chsets = get_bits(&s->gb, 2) + 1;

    for(i = 0; i < num_chsets; i++)
        chset_fsize[i] = get_bits(&s->gb, 14) + 1;

    xbr_tmode = get_bits1(&s->gb);

    for(i = 0; i < num_chsets; i++) {
        n_xbr_ch[i] = get_bits(&s->gb, 3) + 1;
        k = get_bits(&s->gb, 2) + 5;
        for(j = 0; j < n_xbr_ch[i]; j++)
            active_bands[i][j] = get_bits(&s->gb, k) + 1;
    }

    /* skip to the end of the header */
    i = get_bits_count(&s->gb);
    if(hdr_pos + hdr_size * 8 > i)
        skip_bits_long(&s->gb, hdr_pos + hdr_size * 8 - i);

    /* loop over the channel data sets */
    /* only decode as many channels as we've decoded base data for */
    for(chset = 0, chan_base = 0;
        chset < num_chsets && chan_base + n_xbr_ch[chset] <= s->prim_channels;
        chan_base += n_xbr_ch[chset++]) {
        int start_posn = get_bits_count(&s->gb);
        int subsubframe = 0;
        int subframe = 0;

        /* loop over subframes */
        for (k = 0; k < (s->sample_blocks / 8); k++) {
            /* parse header if we're on first subsubframe of a block */
            if(subsubframe == 0) {
                /* Parse subframe header */
                for(i = 0; i < n_xbr_ch[chset]; i++) {
                    anctemp[i] = get_bits(&s->gb, 2) + 2;
                }

                for(i = 0; i < n_xbr_ch[chset]; i++) {
                    get_array(&s->gb, abits_high[i], active_bands[chset][i], anctemp[i]);
                }

                for(i = 0; i < n_xbr_ch[chset]; i++) {
                    anctemp[i] = get_bits(&s->gb, 3);
                    if(anctemp[i] < 1) {
                        av_log(s->avctx, AV_LOG_ERROR, "DTS-XBR: SYNC ERROR\n");
                        return AVERROR_INVALIDDATA;
                    }
                }

                /* generate scale factors */
                for(i = 0; i < n_xbr_ch[chset]; i++) {
                    const uint32_t *scale_table;
                    int nbits;

                    if (s->scalefactor_huffman[chan_base+i] == 6) {
                        scale_table = ff_dca_scale_factor_quant7;
                    } else {
                        scale_table = ff_dca_scale_factor_quant6;
                    }

                    nbits = anctemp[i];

                    for(j = 0; j < active_bands[chset][i]; j++) {
                        if(abits_high[i][j] > 0) {
                            scale_table_high[i][j][0] =
                                scale_table[get_bits(&s->gb, nbits)];

                            if(xbr_tmode && s->transition_mode[i][j]) {
                                scale_table_high[i][j][1] =
                                    scale_table[get_bits(&s->gb, nbits)];
                            }
                        }
                    }
                }
            }

            /* decode audio array for this block */
            for(i = 0; i < n_xbr_ch[chset]; i++) {
                for(j = 0; j < active_bands[chset][i]; j++) {
                    const int xbr_abits = abits_high[i][j];
                    const float quant_step_size = ff_dca_lossless_quant_d[xbr_abits];
                    const int sfi = xbr_tmode && s->transition_mode[i][j] && subsubframe >= s->transition_mode[i][j];
                    const float rscale = quant_step_size * scale_table_high[i][j][sfi];
                    float *subband_samples = s->subband_samples[k][chan_base+i][j];
                    int block[8];

                    if(xbr_abits <= 0)
                        continue;

                    if(xbr_abits > 7) {
                        get_array(&s->gb, block, 8, xbr_abits - 3);
                    } else {
                        int block_code1, block_code2, size, levels, err;

                        size   = abits_sizes[xbr_abits - 1];
                        levels = abits_levels[xbr_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: DTS-XBR: block code look-up failed\n");
                            return AVERROR_INVALIDDATA;
                        }
                    }

                    /* scale & sum into subband */
                    for(l = 0; l < 8; l++)
                        subband_samples[l] += (float)block[l] * rscale;
                }
            }

            /* check DSYNC marker */
            if(s->aspf || subsubframe == s->subsubframes[subframe] - 1) {
                if(get_bits(&s->gb, 16) != 0xffff) {
                    av_log(s->avctx, AV_LOG_ERROR, "DTS-XBR: Didn't get subframe DSYNC\n");
                    return AVERROR_INVALIDDATA;
                }
            }

            /* advance sub-sub-frame index */
            if(++subsubframe >= s->subsubframes[subframe]) {
                subsubframe = 0;
                subframe++;
            }
        }

        /* skip to next channel set */
        i = get_bits_count(&s->gb);
        if(start_posn + chset_fsize[chset] * 8 != i) {
            j = start_posn + chset_fsize[chset] * 8 - i;
            if(j < 0 || j >= 8)
                av_log(s->avctx, AV_LOG_ERROR, "DTS-XBR: end of channel set,"
                       " skipping further than expected (%d bits)\n", j);
            skip_bits_long(&s->gb, j);
        }
    }

    return 0;
}


/* parse initial header for XXCH and dump details */
int ff_dca_xxch_decode_frame(DCAContext *s)
{
    int hdr_size, spkmsk_bits, num_chsets, core_spk, hdr_pos;
    int i, chset, base_channel, chstart, fsize[8];

    /* assume header word has already been parsed */
    hdr_pos     = get_bits_count(&s->gb) - 32;
    hdr_size    = get_bits(&s->gb, 6) + 1;
  /*chhdr_crc   =*/ skip_bits1(&s->gb);
    spkmsk_bits = get_bits(&s->gb, 5) + 1;
    num_chsets  = get_bits(&s->gb, 2) + 1;

    for (i = 0; i < num_chsets; i++)
        fsize[i] = get_bits(&s->gb, 14) + 1;

    core_spk               = get_bits(&s->gb, spkmsk_bits);
    s->xxch_core_spkmask   = core_spk;
    s->xxch_nbits_spk_mask = spkmsk_bits;
    s->xxch_dmix_embedded  = 0;

    /* skip to the end of the header */
    i = get_bits_count(&s->gb);
    if (hdr_pos + hdr_size * 8 > i)
        skip_bits_long(&s->gb, hdr_pos + hdr_size * 8 - i);

    for (chset = 0; chset < num_chsets; chset++) {
        chstart       = get_bits_count(&s->gb);
        base_channel  = s->prim_channels;
        s->xxch_chset = chset;

        /* XXCH and Core headers differ, see 6.4.2 "XXCH Channel Set Header" vs.
           5.3.2 "Primary Audio Coding Header", DTS Spec 1.3.1 */
        dca_parse_audio_coding_header(s, base_channel, 1);

        /* decode channel data */
        for (i = 0; i < (s->sample_blocks / 8); i++) {
            if (dca_decode_block(s, base_channel, i)) {
                av_log(s->avctx, AV_LOG_ERROR,
                       "Error decoding DTS-XXCH extension\n");
                continue;
            }
        }

        /* skip to end of this section */
        i = get_bits_count(&s->gb);
        if (chstart + fsize[chset] * 8 > i)
            skip_bits_long(&s->gb, chstart + fsize[chset] * 8 - i);
    }
    s->xxch_chset = num_chsets;

    return 0;
}

static float dca_dmix_code(unsigned code)
{
    int sign = (code >> 8) - 1;
    code &= 0xff;
    return ((ff_dca_dmixtable[code] ^ sign) - sign) * (1.0 / (1 << 15));
}

/**
 * Main frame decoding function
 * FIXME add arguments
 */
static int dca_decode_frame(AVCodecContext *avctx, void *data,
                            int *got_frame_ptr, AVPacket *avpkt)
{
    AVFrame *frame     = data;
    const uint8_t *buf = avpkt->data;
    int buf_size       = avpkt->size;
    int channel_mask;
    int channel_layout;
    int lfe_samples;
    int num_core_channels = 0;
    int i, ret;
    float **samples_flt;
    float *src_chan;
    float *dst_chan;
    DCAContext *s = avctx->priv_data;
    int core_ss_end;
    int channels, full_channels;
    float scale;
    int achan;
    int chset;
    int mask;
    int lavc;
    int posn;
    int j, k;
    int endch;

    s->xch_present = 0;

    s->dca_buffer_size = avpriv_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;
    }

    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->prim_channels + !!s->lfe > 2 &&
        avctx->request_channel_layout == AV_CH_LAYOUT_STEREO) {
            /* Stereo downmix coefficients
             *
             * The decoder can only downmix to 2-channel, so we need to ensure
             * embedded downmix coefficients are actually targeting 2-channel.
             */
            if (s->core_downmix && (s->core_downmix_amode == DCA_STEREO ||
                                    s->core_downmix_amode == DCA_STEREO_TOTAL)) {
                for (i = 0; i < num_core_channels + !!s->lfe; i++) {
                    /* Range checked earlier */
                    s->downmix_coef[i][0] = dca_dmix_code(s->core_downmix_codes[i][0]);
                    s->downmix_coef[i][1] = dca_dmix_code(s->core_downmix_codes[i][1]);
                }
                s->output = s->core_downmix_amode;
            } else {
                int am = s->amode & DCA_CHANNEL_MASK;
                if (am >= FF_ARRAY_ELEMS(ff_dca_default_coeffs)) {
                    av_log(s->avctx, AV_LOG_ERROR,
                           "Invalid channel mode %d\n", am);
                    return AVERROR_INVALIDDATA;
                }
                if (num_core_channels + !!s->lfe >
                    FF_ARRAY_ELEMS(ff_dca_default_coeffs[0])) {
                    avpriv_request_sample(s->avctx, "Downmixing %d channels",
                                          s->prim_channels + !!s->lfe);
                    return AVERROR_PATCHWELCOME;
                }
                for (i = 0; i < num_core_channels + !!s->lfe; i++) {
                    s->downmix_coef[i][0] = ff_dca_default_coeffs[am][i][0];
                    s->downmix_coef[i][1] = ff_dca_default_coeffs[am][i][1];
                }
            }
            av_dlog(s->avctx, "Stereo downmix coeffs:\n");
            for (i = 0; i < num_core_channels + !!s->lfe; i++) {
                av_dlog(s->avctx, "L, input channel %d = %f\n", i,
                        s->downmix_coef[i][0]);
                av_dlog(s->avctx, "R, input channel %d = %f\n", i,
                        s->downmix_coef[i][1]);
            }
            av_dlog(s->avctx, "\n");
    }

    if (s->ext_coding)
        s->core_ext_mask = ff_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 | DCA_EXT_XXCH)) {
        /* 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 DCA_SYNCWORD_XCH: {
                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;
                }

                if (s->xch_base_channel < 2) {
                    avpriv_request_sample(avctx, "XCh with fewer than 2 base channels");
                    continue;
                }

                /* much like core primary audio coding header */
                dca_parse_audio_coding_header(s, s->xch_base_channel, 0);

                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 DCA_SYNCWORD_XXCH:
                /* 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;
                ff_dca_xxch_decode_frame(s);
                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_SYNCWORD_SUBSTREAM)
        ff_dca_exss_parse_header(s);

    avctx->profile = s->profile;

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

    /* If we have XXCH then the channel layout is managed differently */
    /* note that XLL will also have another way to do things */
    if (!(s->core_ext_mask & DCA_EXT_XXCH)
        || (s->core_ext_mask & DCA_EXT_XXCH && avctx->request_channels > 0
            && avctx->request_channels
            < num_core_channels + !!s->lfe + s->xxch_chset_nch[0]))
    { /* xxx should also do MA extensions */
        if (s->amode < 16) {
            avctx->channel_layout = ff_dca_core_channel_layout[s->amode];

            if (s->prim_channels + !!s->lfe > 2 &&
                avctx->request_channel_layout == AV_CH_LAYOUT_STEREO) {
                /*
                 * Neither the core's auxiliary data nor our default tables contain
                 * downmix coefficients for the additional channel coded in the XCh
                 * extension, so when we're doing a Stereo downmix, don't decode it.
                 */
                s->xch_disable = 1;
            }

#if FF_API_REQUEST_CHANNELS
FF_DISABLE_DEPRECATION_WARNINGS
            if (s->xch_present && !s->xch_disable &&
                (!avctx->request_channels ||
                 avctx->request_channels > num_core_channels + !!s->lfe)) {
FF_ENABLE_DEPRECATION_WARNINGS
#else
            if (s->xch_present && !s->xch_disable) {
#endif
                if (avctx->channel_layout & AV_CH_BACK_CENTER) {
                    avpriv_request_sample(avctx, "XCh with Back center channel");
                    return AVERROR_INVALIDDATA;
                }
                avctx->channel_layout |= AV_CH_BACK_CENTER;
                if (s->lfe) {
                    avctx->channel_layout |= AV_CH_LOW_FREQUENCY;
                    s->channel_order_tab = ff_dca_channel_reorder_lfe_xch[s->amode];
                } else {
                    s->channel_order_tab = ff_dca_channel_reorder_nolfe_xch[s->amode];
                }
                if (s->channel_order_tab[s->xch_base_channel] < 0)
                    return AVERROR_INVALIDDATA;
            } 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 = ff_dca_channel_reorder_lfe[s->amode];
                } else
                    s->channel_order_tab = ff_dca_channel_reorder_nolfe[s->amode];
            }

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

            if (av_get_channel_layout_nb_channels(avctx->channel_layout) != channels) {
                av_log(avctx, AV_LOG_ERROR, "Number of channels %d mismatches layout %d\n", channels, av_get_channel_layout_nb_channels(avctx->channel_layout));
                return AVERROR_INVALIDDATA;
            }

            if (num_core_channels + !!s->lfe > 2 &&
                avctx->request_channel_layout == AV_CH_LAYOUT_STEREO) {
                channels              = 2;
                s->output             = s->prim_channels == 2 ? s->amode : DCA_STEREO;
                avctx->channel_layout = AV_CH_LAYOUT_STEREO;
            }
            else if (avctx->request_channel_layout & AV_CH_LAYOUT_NATIVE) {
                static const int8_t dca_channel_order_native[9] = { 0, 1, 2, 3, 4, 5, 6, 7, 8 };
                s->channel_order_tab = dca_channel_order_native;
            }
            s->lfe_index = ff_dca_lfe_index[s->amode];
        } else {
            av_log(avctx, AV_LOG_ERROR,
                   "Non standard configuration %d !\n", s->amode);
            return AVERROR_INVALIDDATA;
        }

        s->xxch_dmix_embedded = 0;
    } else {
        /* we only get here if an XXCH channel set can be added to the mix */
        channel_mask = s->xxch_core_spkmask;

        if (avctx->request_channels > 0
            && avctx->request_channels < s->prim_channels) {
            channels = num_core_channels + !!s->lfe;
            for (i = 0; i < s->xxch_chset && channels + s->xxch_chset_nch[i]
                                              <= avctx->request_channels; i++) {
                channels += s->xxch_chset_nch[i];
                channel_mask |= s->xxch_spk_masks[i];
            }
        } else {
            channels = s->prim_channels + !!s->lfe;
            for (i = 0; i < s->xxch_chset; i++) {
                channel_mask |= s->xxch_spk_masks[i];
            }
        }

        /* Given the DTS spec'ed channel mask, generate an avcodec version */
        channel_layout = 0;
        for (i = 0; i < s->xxch_nbits_spk_mask; ++i) {
            if (channel_mask & (1 << i)) {
                channel_layout |= ff_dca_map_xxch_to_native[i];
            }
        }

        /* make sure that we have managed to get equivalent dts/avcodec channel
         * masks in some sense -- unfortunately some channels could overlap */
        if (av_popcount(channel_mask) != av_popcount(channel_layout)) {
            av_log(avctx, AV_LOG_DEBUG,
                   "DTS-XXCH: Inconsistent avcodec/dts channel layouts\n");
            return AVERROR_INVALIDDATA;
        }

        avctx->channel_layout = channel_layout;

        if (!(avctx->request_channel_layout & AV_CH_LAYOUT_NATIVE)) {
            /* Estimate DTS --> avcodec ordering table */
            for (chset = -1, j = 0; chset < s->xxch_chset; ++chset) {
                mask = chset >= 0 ? s->xxch_spk_masks[chset]
                                  : s->xxch_core_spkmask;
                for (i = 0; i < s->xxch_nbits_spk_mask; i++) {
                    if (mask & ~(DCA_XXCH_LFE1 | DCA_XXCH_LFE2) & (1 << i)) {
                        lavc = ff_dca_map_xxch_to_native[i];
                        posn = av_popcount(channel_layout & (lavc - 1));
                        s->xxch_order_tab[j++] = posn;
                    }
                }

            }

            s->lfe_index = av_popcount(channel_layout & (AV_CH_LOW_FREQUENCY-1));
        } else { /* native ordering */
            for (i = 0; i < channels; i++)
                s->xxch_order_tab[i] = i;

            s->lfe_index = channels - 1;
        }

        s->channel_order_tab = s->xxch_order_tab;
    }

    if (avctx->channels != channels) {
        if (avctx->channels)
            av_log(avctx, AV_LOG_INFO, "Number of channels changed in DCA decoder (%d -> %d)\n", avctx->channels, channels);
        avctx->channels = channels;
    }

    /* get output buffer */
    frame->nb_samples = 256 * (s->sample_blocks / 8);
    if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
        return ret;
    samples_flt = (float **) frame->extended_data;

    /* allocate buffer for extra channels if downmixing */
    if (avctx->channels < full_channels) {
        ret = av_samples_get_buffer_size(NULL, full_channels - channels,
                                         frame->nb_samples,
                                         avctx->sample_fmt, 0);
        if (ret < 0)
            return ret;

        av_fast_malloc(&s->extra_channels_buffer,
                       &s->extra_channels_buffer_size, ret);
        if (!s->extra_channels_buffer)
            return AVERROR(ENOMEM);

        ret = av_samples_fill_arrays((uint8_t **) s->extra_channels, NULL,
                                     s->extra_channels_buffer,
                                     full_channels - channels,
                                     frame->nb_samples, avctx->sample_fmt, 0);
        if (ret < 0)
            return ret;
    }

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

        for (ch = 0; ch < channels; ch++)
            s->samples_chanptr[ch] = samples_flt[ch] + i * 256;
        for (; ch < full_channels; ch++)
            s->samples_chanptr[ch] = s->extra_channels[ch - channels] + i * 256;

        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_chanptr[s->channel_order_tab[s->xch_base_channel]];
            float *lt_chan   = s->samples_chanptr[s->channel_order_tab[s->xch_base_channel - 2]];
            float *rt_chan   = s->samples_chanptr[s->channel_order_tab[s->xch_base_channel - 1]];
            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 stream contains XXCH, we might need to undo an embedded downmix */
        if (s->xxch_dmix_embedded) {
            /* Loop over channel sets in turn */
            ch = num_core_channels;
            for (chset = 0; chset < s->xxch_chset; chset++) {
                endch = ch + s->xxch_chset_nch[chset];
                mask = s->xxch_dmix_embedded;

                /* undo downmix */
                for (j = ch; j < endch; j++) {
                    if (mask & (1 << j)) { /* this channel has been mixed-out */
                        src_chan = s->samples_chanptr[s->channel_order_tab[j]];
                        for (k = 0; k < endch; k++) {
                            achan = s->channel_order_tab[k];
                            scale = s->xxch_dmix_coeff[j][k];
                            if (scale != 0.0) {
                                dst_chan = s->samples_chanptr[achan];
                                s->fdsp->vector_fmac_scalar(dst_chan, src_chan,
                                                           -scale, 256);
                            }
                        }
                    }
                }

                /* if a downmix has been embedded then undo the pre-scaling */
                if ((mask & (1 << ch)) && s->xxch_dmix_sf[chset] != 1.0f) {
                    scale = s->xxch_dmix_sf[chset];

                    for (j = 0; j < ch; j++) {
                        src_chan = s->samples_chanptr[s->channel_order_tab[j]];
                        for (k = 0; k < 256; k++)
                            src_chan[k] *= scale;
                    }

                    /* LFE channel is always part of core, scale if it exists */
                    if (s->lfe) {
                        src_chan = s->samples_chanptr[s->lfe_index];
                        for (k = 0; k < 256; k++)
                            src_chan[k] *= scale;
                    }
                }

                ch = endch;
            }

        }
    }

    /* 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];

    /* AVMatrixEncoding
     *
     * DCA_STEREO_TOTAL (Lt/Rt) is equivalent to Dolby Surround */
    ret = ff_side_data_update_matrix_encoding(frame,
                                              (s->output & ~DCA_LFE) == DCA_STEREO_TOTAL ?
                                              AV_MATRIX_ENCODING_DOLBY : AV_MATRIX_ENCODING_NONE);
    if (ret < 0)
        return ret;

    *got_frame_ptr = 1;

    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;

    s->avctx = avctx;
    dca_init_vlcs();

    s->fdsp = avpriv_float_dsp_alloc(avctx->flags & CODEC_FLAG_BITEXACT);
    if (!s->fdsp)
        return AVERROR(ENOMEM);

    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);

    avctx->sample_fmt = AV_SAMPLE_FMT_FLTP;

    /* allow downmixing to stereo */
#if FF_API_REQUEST_CHANNELS
FF_DISABLE_DEPRECATION_WARNINGS
    if (avctx->request_channels == 2)
        avctx->request_channel_layout = AV_CH_LAYOUT_STEREO;
FF_ENABLE_DEPRECATION_WARNINGS
#endif
    if (avctx->channels > 2 &&
        avctx->request_channel_layout == AV_CH_LAYOUT_STEREO)
        avctx->channels = 2;

    return 0;
}

static av_cold int dca_decode_end(AVCodecContext *avctx)
{
    DCAContext *s = avctx->priv_data;
    ff_mdct_end(&s->imdct);
    av_freep(&s->extra_channels_buffer);
    av_freep(&s->fdsp);
    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 },
};

static const AVOption options[] = {
    { "disable_xch", "disable decoding of the XCh extension", offsetof(DCAContext, xch_disable), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 1, AV_OPT_FLAG_DECODING_PARAM | AV_OPT_FLAG_AUDIO_PARAM },
    { NULL },
};

static const AVClass dca_decoder_class = {
    .class_name = "DCA decoder",
    .item_name  = av_default_item_name,
    .option     = options,
    .version    = LIBAVUTIL_VERSION_INT,
    .category   = AV_CLASS_CATEGORY_DECODER,
};

AVCodec ff_dca_decoder = {
    .name            = "dca",
    .long_name       = NULL_IF_CONFIG_SMALL("DCA (DTS Coherent Acoustics)"),
    .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,
    .capabilities    = CODEC_CAP_CHANNEL_CONF | CODEC_CAP_DR1,
    .sample_fmts     = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_FLTP,
                                                       AV_SAMPLE_FMT_NONE },
    .profiles        = NULL_IF_CONFIG_SMALL(profiles),
    .priv_class      = &dca_decoder_class,
};
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root/libavcodec/dcadec.c

DEFINITIONS
