dca: Support for XLL (lossless extension)

Cleanup and integration by Diego Biurrun.

Signed-off-by: Diego Biurrun <diego@biurrun.de>

1 files changed, 747 insertions, 0 deletions

diff --git a/libavcodec/dca_xll.c b/libavcodec/dca_xll.c
new file mode 100644
index 0000000000..0c32d6ecce
--- /dev/null
+++ b/libavcodec/dca_xll.c
@@ -0,0 +1,747 @@
+/*
+ * DCA XLL extension
+ *
+ * Copyright (C) 2012 Paul B Mahol
+ * Copyright (C) 2014 Niels Möller
+ *
+ * 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 "libavutil/attributes.h"
+#include "libavutil/common.h"
+#include "libavutil/internal.h"
+
+#include "avcodec.h"
+#include "dca.h"
+#include "dcadata.h"
+#include "get_bits.h"
+#include "unary.h"
+
+/* Sign as bit 0 */
+static inline int get_bits_sm(GetBitContext *s, unsigned n)
+{
+    int x = get_bits(s, n);
+    if (x & 1)
+        return -(x >> 1) - 1;
+    else
+        return x >> 1;
+}
+
+/* Return -1 on error. */
+static int32_t get_dmix_coeff(DCAContext *s, int inverse)
+{
+    unsigned code = get_bits(&s->gb, 9);
+    int32_t sign = (int32_t) (code >> 8) - 1;
+    unsigned idx = code & 0xff;
+    int inv_offset = FF_DCA_DMIXTABLE_SIZE -FF_DCA_INV_DMIXTABLE_SIZE;
+    if (idx >= FF_DCA_DMIXTABLE_SIZE) {
+        av_log(s->avctx, AV_LOG_ERROR,
+               "XLL: Invalid channel set downmix code %x\n", code);
+        return -1;
+    } else if (!inverse) {
+        return (ff_dca_dmixtable[idx] ^ sign) - sign;
+    } else if (idx < inv_offset) {
+        av_log(s->avctx, AV_LOG_ERROR,
+               "XLL: Invalid channel set inverse downmix code %x\n", code);
+        return -1;
+    } else {
+        return (ff_dca_inv_dmixtable[idx - inv_offset] ^ sign) - sign;
+    }
+}
+
+static int32_t dca_get_dmix_coeff(DCAContext *s)
+{
+    return get_dmix_coeff(s, 0);
+}
+
+static int32_t dca_get_inv_dmix_coeff(DCAContext *s)
+{
+    return get_dmix_coeff(s, 1);
+}
+
+/* parse XLL header */
+int ff_dca_xll_decode_header(DCAContext *s)
+{
+    int hdr_pos, hdr_size;
+    av_unused int version, frame_size;
+    int i, chset_index;
+
+    /* get bit position of sync header */
+    hdr_pos    = get_bits_count(&s->gb) - 32;
+
+    version    = get_bits(&s->gb, 4) + 1;
+    hdr_size   = get_bits(&s->gb, 8) + 1;
+
+    frame_size = get_bits_long(&s->gb, get_bits(&s->gb, 5) + 1) + 1;
+
+    s->xll_channels          =
+    s->xll_residual_channels = 0;
+    s->xll_nch_sets          = get_bits(&s->gb, 4) + 1;
+    s->xll_segments          = 1 << get_bits(&s->gb, 4);
+    s->xll_log_smpl_in_seg   = get_bits(&s->gb, 4);
+    s->xll_smpl_in_seg       = 1 << s->xll_log_smpl_in_seg;
+    s->xll_bits4seg_size     = get_bits(&s->gb, 5) + 1;
+    s->xll_banddata_crc      = get_bits(&s->gb, 2);
+    s->xll_scalable_lsb      = get_bits1(&s->gb);
+    s->xll_bits4ch_mask      = get_bits(&s->gb, 5) + 1;
+
+    if (s->xll_scalable_lsb) {
+        s->xll_fixed_lsb_width = get_bits(&s->gb, 4);
+        if (s->xll_fixed_lsb_width)
+            av_log(s->avctx, AV_LOG_WARNING,
+                   "XLL: fixed lsb width = %d, non-zero not supported.\n",
+                   s->xll_fixed_lsb_width);
+    }
+    /* skip to the end of the common 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_index = 0; chset_index < s->xll_nch_sets; chset_index++) {
+        XllChSetSubHeader *chset = &s->xll_chsets[chset_index];
+        hdr_pos  = get_bits_count(&s->gb);
+        hdr_size = get_bits(&s->gb, 10) + 1;
+
+        chset->channels           = get_bits(&s->gb, 4) + 1;
+        chset->residual_encode    = get_bits(&s->gb, chset->channels);
+        chset->bit_resolution     = get_bits(&s->gb, 5) + 1;
+        chset->bit_width          = get_bits(&s->gb, 5) + 1;
+        chset->sampling_frequency = ff_dca_sampling_freqs[get_bits(&s->gb, 4)];
+        chset->samp_freq_interp   = get_bits(&s->gb, 2);
+        chset->replacement_set    = get_bits(&s->gb, 2);
+        if (chset->replacement_set)
+            chset->active_replace_set = get_bits(&s->gb, 1);
+
+        if (s->one2one_map_chtospkr) {
+            chset->primary_ch_set              = get_bits(&s->gb, 1);
+            chset->downmix_coeff_code_embedded = get_bits(&s->gb, 1);
+            if (chset->downmix_coeff_code_embedded) {
+                chset->downmix_embedded = get_bits(&s->gb, 1);
+                if (chset->primary_ch_set) {
+                    chset->downmix_type = get_bits(&s->gb, 3);
+                    if (chset->downmix_type > 6) {
+                        av_log(s->avctx, AV_LOG_ERROR,
+                               "XLL: Invalid channel set downmix type\n");
+                        return AVERROR_INVALIDDATA;
+                    }
+                }
+            }
+            chset->hier_chset = get_bits(&s->gb, 1);
+
+            if (chset->downmix_coeff_code_embedded) {
+                /* nDownmixCoeffs is specified as N * M. For a primary
+                 * channel set, it appears that N = number of
+                 * channels, and M is the number of downmix channels.
+                 *
+                 * For a non-primary channel set, N is specified as
+                 * number of channels + 1, and M is derived from the
+                 * channel set hierarchy, and at least in simple cases
+                 * M is the number of channels in preceding channel
+                 * sets. */
+                if (chset->primary_ch_set) {
+                    static const char dmix_table[7] = { 1, 2, 2, 3, 3, 4, 4 };
+                    chset->downmix_ncoeffs = chset->channels * dmix_table[chset->downmix_type];
+                } else
+                    chset->downmix_ncoeffs = (chset->channels + 1) * s->xll_channels;
+
+                if (chset->downmix_ncoeffs > DCA_XLL_DMIX_NCOEFFS_MAX) {
+                    avpriv_request_sample(s->avctx,
+                                          "XLL: More than %d downmix coefficients",
+                                          DCA_XLL_DMIX_NCOEFFS_MAX);
+                    return AVERROR_PATCHWELCOME;
+                } else if (chset->primary_ch_set) {
+                    for (i = 0; i < chset->downmix_ncoeffs; i++)
+                        if ((chset->downmix_coeffs[i] = dca_get_dmix_coeff(s)) == -1)
+                            return AVERROR_INVALIDDATA;
+                } else {
+                    unsigned c, r;
+                    for (c = 0, i = 0; c < s->xll_channels; c++, i += chset->channels + 1) {
+                        if ((chset->downmix_coeffs[i] = dca_get_inv_dmix_coeff(s)) == -1)
+                            return AVERROR_INVALIDDATA;
+                        for (r = 1; r <= chset->channels; r++) {
+                            int32_t coeff = dca_get_dmix_coeff(s);
+                            if (coeff == -1)
+                                return AVERROR_INVALIDDATA;
+                            chset->downmix_coeffs[i + r] =
+                                (chset->downmix_coeffs[i] * (int64_t) coeff + (1 << 15)) >> 16;
+                        }
+                    }
+                }
+            }
+            chset->ch_mask_enabled = get_bits(&s->gb, 1);
+            if (chset->ch_mask_enabled)
+                chset->ch_mask = get_bits(&s->gb, s->xll_bits4ch_mask);
+            else
+                /* Skip speaker configuration bits */
+                skip_bits_long(&s->gb, 25 * chset->channels);
+        } else {
+            chset->primary_ch_set              = 1;
+            chset->downmix_coeff_code_embedded = 0;
+            /* Spec: NumChHierChSet = 0, NumDwnMixCodeCoeffs = 0, whatever that means. */
+            chset->mapping_coeffs_present = get_bits(&s->gb, 1);
+            if (chset->mapping_coeffs_present) {
+                avpriv_report_missing_feature(s->avctx, "XLL: mapping coefficients");
+                return AVERROR_PATCHWELCOME;
+            }
+        }
+        if (chset->sampling_frequency > 96000)
+            chset->num_freq_bands = 2 * (1 + get_bits(&s->gb, 1));
+        else
+            chset->num_freq_bands = 1;
+
+        if (chset->num_freq_bands > 1) {
+            avpriv_report_missing_feature(s->avctx, "XLL: num_freq_bands > 1");
+            return AVERROR_PATCHWELCOME;
+        }
+
+        if (get_bits(&s->gb, 1)) { /* pw_ch_decor_enabled */
+            int bits = av_ceil_log2(chset->channels);
+            for (i = 0; i < chset->channels; i++) {
+                unsigned j = get_bits(&s->gb, bits);
+                if (j >= chset->channels) {
+                    av_log(s->avctx, AV_LOG_ERROR,
+                           "Original channel order value %u too large, only %d channels.\n",
+                           j, chset->channels);
+                    return AVERROR_INVALIDDATA;
+                }
+                chset->orig_chan_order[0][i]     = j;
+                chset->orig_chan_order_inv[0][j] = i;
+            }
+            for (i = 0; i < chset->channels / 2; i++) {
+                if (get_bits(&s->gb, 1)) /* bChPFlag */
+                    chset->pw_ch_pairs_coeffs[0][i] = get_bits_sm(&s->gb, 7);
+                else
+                    chset->pw_ch_pairs_coeffs[0][i] = 0;
+            }
+        } else {
+            for (i = 0; i < chset->channels; i++)
+                chset->orig_chan_order[0][i]     =
+                chset->orig_chan_order_inv[0][i] = i;
+            for (i = 0; i < chset->channels / 2; i++)
+                chset->pw_ch_pairs_coeffs[0][i] = 0;
+        }
+        /* Adaptive prediction order */
+        chset->adapt_order_max[0] = 0;
+        for (i = 0; i < chset->channels; i++) {
+            chset->adapt_order[0][i] = get_bits(&s->gb, 4);
+            if (chset->adapt_order_max[0] < chset->adapt_order[0][i])
+                chset->adapt_order_max[0] = chset->adapt_order[0][i];
+        }
+        /* Fixed prediction order, used in case the adaptive order
+         * above is zero */
+        for (i = 0; i < chset->channels; i++)
+            chset->fixed_order[0][i] =
+                chset->adapt_order[0][i] ? 0 : get_bits(&s->gb, 2);
+
+        for (i = 0; i < chset->channels; i++) {
+            unsigned j;
+            for (j = 0; j < chset->adapt_order[0][i]; j++)
+                chset->lpc_refl_coeffs_q_ind[0][i][j] = get_bits(&s->gb, 8);
+        }
+
+        if (s->xll_scalable_lsb) {
+            chset->lsb_fsize[0] = get_bits(&s->gb, s->xll_bits4seg_size);
+
+            for (i = 0; i < chset->channels; i++)
+                chset->scalable_lsbs[0][i] = get_bits(&s->gb, 4);
+            for (i = 0; i < chset->channels; i++)
+                chset->bit_width_adj_per_ch[0][i] = get_bits(&s->gb, 4);
+        } else {
+            memset(chset->scalable_lsbs[0], 0,
+                   chset->channels * sizeof(chset->scalable_lsbs[0][0]));
+            memset(chset->bit_width_adj_per_ch[0], 0,
+                   chset->channels * sizeof(chset->bit_width_adj_per_ch[0][0]));
+        }
+
+        s->xll_channels          += chset->channels;
+        s->xll_residual_channels += chset->channels -
+                                    av_popcount(chset->residual_encode);
+
+        /* FIXME: Parse header data for extra frequency bands. */
+
+        /* Skip to end of channel set sub header. */
+        i = get_bits_count(&s->gb);
+        if (hdr_pos + 8 * hdr_size < i) {
+            av_log(s->avctx, AV_LOG_ERROR,
+                   "chset header too large, %d bits, should be <= %d bits\n",
+                   i - hdr_pos, 8 * hdr_size);
+            return AVERROR_INVALIDDATA;
+        }
+        if (hdr_pos + 8 * hdr_size > i)
+            skip_bits_long(&s->gb, hdr_pos + 8 * hdr_size - i);
+    }
+    return 0;
+}
+
+/* parse XLL navigation table */
+int ff_dca_xll_decode_navi(DCAContext *s, int asset_end)
+{
+    int nbands, band, chset, seg, data_start;
+
+    /* FIXME: Supports only a single frequency band */
+    nbands = 1;
+
+    for (band = 0; band < nbands; band++) {
+        s->xll_navi.band_size[band] = 0;
+        for (seg = 0; seg < s->xll_segments; seg++) {
+            /* Note: The spec, ETSI TS 102 114 V1.4.1 (2012-09), says
+             * we should read a base value for segment_size from the
+             * stream, before reading the sizes of the channel sets.
+             * But that's apparently incorrect. */
+            s->xll_navi.segment_size[band][seg] = 0;
+
+            for (chset = 0; chset < s->xll_nch_sets; chset++)
+                if (band < s->xll_chsets[chset].num_freq_bands) {
+                    s->xll_navi.chset_size[band][seg][chset] =
+                        get_bits(&s->gb, s->xll_bits4seg_size) + 1;
+                    s->xll_navi.segment_size[band][seg] +=
+                        s->xll_navi.chset_size[band][seg][chset];
+                }
+            s->xll_navi.band_size[band] += s->xll_navi.segment_size[band][seg];
+        }
+    }
+    /* Align to 8 bits and skip 16-bit CRC. */
+    skip_bits_long(&s->gb, 16 + ((-get_bits_count(&s->gb)) & 7));
+
+    data_start = get_bits_count(&s->gb);
+    if (data_start + 8 * s->xll_navi.band_size[0] > asset_end) {
+        av_log(s->avctx, AV_LOG_ERROR,
+               "XLL: Data in NAVI table exceeds containing asset\n"
+               "start: %d (bit), size %u (bytes), end %d (bit), error %u\n",
+               data_start, s->xll_navi.band_size[0], asset_end,
+               data_start + 8 * s->xll_navi.band_size[0] - asset_end);
+        return AVERROR_INVALIDDATA;
+    }
+    init_get_bits(&s->xll_navi.gb, s->gb.buffer + data_start / 8,
+                  8 * s->xll_navi.band_size[0]);
+    return 0;
+}
+
+static void dca_xll_inv_adapt_pred(int *samples, int nsamples, unsigned order,
+                                   const int *prev, const uint8_t *q_ind)
+{
+    static const uint16_t table[0x81] = {
+            0,  3070,  5110,  7140,  9156, 11154, 13132, 15085,
+        17010, 18904, 20764, 22588, 24373, 26117, 27818, 29474,
+        31085, 32648, 34164, 35631, 37049, 38418, 39738, 41008,
+        42230, 43404, 44530, 45609, 46642, 47630, 48575, 49477,
+        50337, 51157, 51937, 52681, 53387, 54059, 54697, 55302,
+        55876, 56421, 56937, 57426, 57888, 58326, 58741, 59132,
+        59502, 59852, 60182, 60494, 60789, 61066, 61328, 61576,
+        61809, 62029, 62236, 62431, 62615, 62788, 62951, 63105,
+        63250, 63386, 63514, 63635, 63749, 63855, 63956, 64051,
+        64140, 64224, 64302, 64376, 64446, 64512, 64573, 64631,
+        64686, 64737, 64785, 64830, 64873, 64913, 64950, 64986,
+        65019, 65050, 65079, 65107, 65133, 65157, 65180, 65202,
+        65222, 65241, 65259, 65275, 65291, 65306, 65320, 65333,
+        65345, 65357, 65368, 65378, 65387, 65396, 65405, 65413,
+        65420, 65427, 65434, 65440, 65446, 65451, 65456, 65461,
+        65466, 65470, 65474, 65478, 65481, 65485, 65488, 65491,
+        65535, /* Final value is for the -128 corner case, see below. */
+    };
+    int c[DCA_XLL_AORDER_MAX];
+    int64_t s;
+    unsigned i, j;
+
+    for (i = 0; i < order; i++) {
+        if (q_ind[i] & 1)
+            /* The index value 0xff corresponds to a lookup of entry 0x80 in
+             * the table, and no value is provided in the specification. */
+            c[i] = -table[(q_ind[i] >> 1) + 1];
+        else
+            c[i] = table[q_ind[i] >> 1];
+    }
+    /* The description in the spec is a bit convoluted. We can convert
+     * the reflected values to direct values in place, using a
+     * sequence of reflections operating on two values. */
+    for (i = 1; i < order; i++) {
+        /* i = 1: scale c[0]
+         * i = 2: reflect c[0] <-> c[1]
+         * i = 3: scale c[1], reflect c[0] <-> c[2]
+         * i = 4: reflect c[0] <-> c[3] reflect c[1] <-> c[2]
+         * ... */
+        if (i & 1)
+            c[i / 2] += ((int64_t) c[i] * c[i / 2] + 0x8000) >> 16;
+        for (j = 0; j < i / 2; j++) {
+            int r0 = c[j];
+            int r1 = c[i - j - 1];
+            c[j]         += ((int64_t) c[i] * r1 + 0x8000) >> 16;
+            c[i - j - 1] += ((int64_t) c[i] * r0 + 0x8000) >> 16;
+        }
+    }
+    /* Apply predictor. */
+    /* NOTE: Processing samples in this order means that the
+     * predictor is applied to the newly reconstructed samples. */
+    if (prev) {
+        for (i = 0; i < order; i++) {
+            for (j = s = 0; j < i; j++)
+                s += (int64_t) c[j] * samples[i - 1 - j];
+            for (; j < order; j++)
+                s += (int64_t) c[j] * prev[DCA_XLL_AORDER_MAX + i - 1 - j];
+
+            samples[i] -= av_clip((s + 0x8000) >> 16, -0x1000000, 0xffffff);
+        }
+    }
+    for (i = order; i < nsamples; i++) {
+        for (j = s = 0; j < order; j++)
+            s += (int64_t) c[j] * samples[i - 1 - j];
+
+        /* NOTE: Equations seem to imply addition, while the
+         * pseudocode seems to use subtraction.*/
+        samples[i] -= av_clip((s + 0x8000) >> 16, -0x1000000, 0xffffff);
+    }
+}
+
+int ff_dca_xll_decode_audio(DCAContext *s, AVFrame *frame)
+{
+    /* FIXME: Decodes only the first frequency band. */
+    int seg, chset_i;
+
+    /* Coding parameters for each channel set. */
+    struct coding_params {
+        int seg_type;
+        int rice_code_flag[16];
+        int pancAuxABIT[16];
+        int pancABIT0[16];  /* Not sure what this is */
+        int pancABIT[16];   /* Not sure what this is */
+        int nSamplPart0[16];
+    } param_state[16];
+
+    GetBitContext *gb = &s->xll_navi.gb;
+    int *history;
+
+    /* Layout: First the sample buffer for one segment per channel,
+     * followed by history buffers of DCA_XLL_AORDER_MAX samples for
+     * each channel. */
+    av_fast_malloc(&s->xll_sample_buf, &s->xll_sample_buf_size,
+                   (s->xll_smpl_in_seg + DCA_XLL_AORDER_MAX) *
+                   s->xll_channels * sizeof(*s->xll_sample_buf));
+    if (!s->xll_sample_buf)
+        return AVERROR(ENOMEM);
+
+    history = s->xll_sample_buf + s->xll_smpl_in_seg * s->xll_channels;
+
+    for (seg = 0; seg < s->xll_segments; seg++) {
+        unsigned in_channel;
+
+        for (chset_i = in_channel = 0; chset_i < s->xll_nch_sets; chset_i++) {
+            /* The spec isn't very explicit, but I think the NAVI sizes are in bytes. */
+            int end_pos = get_bits_count(gb) +
+                          8 * s->xll_navi.chset_size[0][seg][chset_i];
+            int i, j;
+            struct coding_params *params = &param_state[chset_i];
+            /* I think this flag means that we should keep seg_type and
+             * other parameters from the previous segment. */
+            int use_seg_state_code_param;
+            XllChSetSubHeader *chset = &s->xll_chsets[chset_i];
+            if (in_channel >= s->avctx->channels)
+                /* FIXME: Could go directly to next segment */
+                goto next_chset;
+
+            if (s->avctx->sample_rate != chset->sampling_frequency) {
+                av_log(s->avctx, AV_LOG_WARNING,
+                       "XLL: unexpected chset sample rate %d, expected %d\n",
+                       chset->sampling_frequency, s->avctx->sample_rate);
+                goto next_chset;
+            }
+            if (seg != 0)
+                use_seg_state_code_param = get_bits(gb, 1);
+            else
+                use_seg_state_code_param = 0;
+
+            if (!use_seg_state_code_param) {
+                int num_param_sets, i;
+                unsigned bits4ABIT;
+
+                params->seg_type = get_bits(gb, 1);
+                num_param_sets   = params->seg_type ? 1 : chset->channels;
+
+                if (chset->bit_width > 16) {
+                    bits4ABIT = 5;
+                } else {
+                    if (chset->bit_width > 8)
+                        bits4ABIT = 4;
+                    else
+                        bits4ABIT = 3;
+                    if (s->xll_nch_sets > 1)
+                        bits4ABIT++;
+                }
+
+                for (i = 0; i < num_param_sets; i++) {
+                    params->rice_code_flag[i] = get_bits(gb, 1);
+                    if (!params->seg_type && params->rice_code_flag[i] && get_bits(gb, 1))
+                        params->pancAuxABIT[i] = get_bits(gb, bits4ABIT) + 1;
+                    else
+                        params->pancAuxABIT[i] = 0;
+                }
+
+                for (i = 0; i < num_param_sets; i++) {
+                    if (!seg) {
+                        /* Parameters for part 1 */
+                        params->pancABIT0[i] = get_bits(gb, bits4ABIT);
+                        if (params->rice_code_flag[i] == 0 && params->pancABIT0[i] > 0)
+                            /* For linear code */
+                            params->pancABIT0[i]++;
+
+                        /* NOTE: In the spec, not indexed by band??? */
+                        if (params->seg_type == 0)
+                            params->nSamplPart0[i] = chset->adapt_order[0][i];
+                        else
+                            params->nSamplPart0[i] = chset->adapt_order_max[0];
+                    } else
+                        params->nSamplPart0[i] = 0;
+
+                    /* Parameters for part 2 */
+                    params->pancABIT[i] = get_bits(gb, bits4ABIT);
+                    if (params->rice_code_flag[i] == 0 && params->pancABIT[i] > 0)
+                        /* For linear code */
+                        params->pancABIT[i]++;
+                }
+            }
+            for (i = 0; i < chset->channels; i++) {
+                int param_index = params->seg_type ? 0 : i;
+                int bits        = params->pancABIT0[param_index];
+                int part0       = params->nSamplPart0[param_index];
+                int *sample_buf = s->xll_sample_buf +
+                                  (in_channel + i) * s->xll_smpl_in_seg;
+
+                if (!params->rice_code_flag[param_index]) {
+                    /* Linear code */
+                    if (bits)
+                        for (j = 0; j < part0; j++)
+                            sample_buf[j] = get_bits_sm(gb, bits);
+                    else
+                        memset(sample_buf, 0, part0 * sizeof(sample_buf[0]));
+
+                    /* Second part */
+                    bits = params->pancABIT[param_index];
+                    if (bits)
+                        for (j = part0; j < s->xll_smpl_in_seg; j++)
+                            sample_buf[j] = get_bits_sm(gb, bits);
+                    else
+                        memset(sample_buf + part0, 0,
+                               (s->xll_smpl_in_seg - part0) * sizeof(sample_buf[0]));
+                } else {
+                    int aux_bits = params->pancAuxABIT[param_index];
+
+                    for (j = 0; j < part0; j++) {
+                        /* FIXME: Is this identical to Golomb code? */
+                        int t = get_unary(gb, 1, 33) << bits;
+                        /* FIXME: Could move this test outside of the loop, for efficiency. */
+                        if (bits)
+                            t |= get_bits(gb, bits);
+                        sample_buf[j] = (t & 1) ? -(t >> 1) - 1 : (t >> 1);
+                    }
+
+                    /* Second part */
+                    bits = params->pancABIT[param_index];
+
+                    /* Follow the spec's suggestion of using the
+                     * buffer also to store the hybrid-rice flags. */
+                    memset(sample_buf + part0, 0,
+                           (s->xll_smpl_in_seg - part0) * sizeof(sample_buf[0]));
+
+                    if (aux_bits > 0) {
+                        /* For hybrid rice encoding, some samples are linearly
+                         * coded. According to the spec, "nBits4SamplLoci" bits
+                         * are used for each index, but this value is not
+                         * defined. I guess we should use log2(xll_smpl_in_seg)
+                         * bits. */
+                        int count = get_bits(gb, s->xll_log_smpl_in_seg);
+                        av_log(s->avctx, AV_LOG_DEBUG, "aux count %d (bits %d)\n",
+                               count, s->xll_log_smpl_in_seg);
+
+                        for (j = 0; j < count; j++)
+                            sample_buf[get_bits(gb, s->xll_log_smpl_in_seg)] = 1;
+                    }
+                    for (j = part0; j < s->xll_smpl_in_seg; j++) {
+                        if (!sample_buf[j]) {
+                            int t = get_unary(gb, 1, 33);
+                            if (bits)
+                                t = (t << bits) | get_bits(gb, bits);
+                            sample_buf[j] = (t & 1) ? -(t >> 1) - 1 : (t >> 1);
+                        } else
+                            sample_buf[j] = get_bits_sm(gb, aux_bits);
+                    }
+                }
+            }
+
+            for (i = 0; i < chset->channels; i++) {
+                unsigned adapt_order = chset->adapt_order[0][i];
+                int *sample_buf = s->xll_sample_buf +
+                                  (in_channel + i) * s->xll_smpl_in_seg;
+                int *prev = history + (in_channel + i) * DCA_XLL_AORDER_MAX;
+
+                if (!adapt_order) {
+                    unsigned order;
+                    for (order = chset->fixed_order[0][i]; order > 0; order--) {
+                        unsigned j;
+                        for (j = 1; j < s->xll_smpl_in_seg; j++)
+                            sample_buf[j] += sample_buf[j - 1];
+                    }
+                } else
+                    /* Inverse adaptive prediction, in place. */
+                    dca_xll_inv_adapt_pred(sample_buf, s->xll_smpl_in_seg,
+                                           adapt_order, seg ? prev : NULL,
+                                           chset->lpc_refl_coeffs_q_ind[0][i]);
+                memcpy(prev, sample_buf + s->xll_smpl_in_seg - DCA_XLL_AORDER_MAX,
+                       DCA_XLL_AORDER_MAX * sizeof(*prev));
+            }
+            for (i = 1; i < chset->channels; i += 2) {
+                int coeff = chset->pw_ch_pairs_coeffs[0][i / 2];
+                if (coeff != 0) {
+                    int *sample_buf = s->xll_sample_buf +
+                                      (in_channel + i) * s->xll_smpl_in_seg;
+                    int *prev = sample_buf - s->xll_smpl_in_seg;
+                    unsigned j;
+                    for (j = 0; j < s->xll_smpl_in_seg; j++)
+                        /* Shift is unspecified, but should apparently be 3. */
+                        sample_buf[j] += ((int64_t) coeff * prev[j] + 4) >> 3;
+                }
+            }
+
+            if (s->xll_scalable_lsb) {
+                int lsb_start = end_pos - 8 * chset->lsb_fsize[0] -
+                                8 * (s->xll_banddata_crc & 2);
+                int done;
+                i = get_bits_count(gb);
+                if (i > lsb_start) {
+                    av_log(s->avctx, AV_LOG_ERROR,
+                           "chset data lsb exceeds NAVI size, end_pos %d, lsb_start %d, pos %d\n",
+                           end_pos, lsb_start, i);
+                    return AVERROR_INVALIDDATA;
+                }
+                if (i < lsb_start)
+                    skip_bits_long(gb, lsb_start - i);
+
+                for (i = done = 0; i < chset->channels; i++) {
+                    int bits = chset->scalable_lsbs[0][i];
+                    if (bits > 0) {
+                        /* The channel reordering is conceptually done
+                         * before adding the lsb:s, so we need to do
+                         * the inverse permutation here. */
+                        unsigned pi = chset->orig_chan_order_inv[0][i];
+                        int *sample_buf = s->xll_sample_buf +
+                                          (in_channel + pi) * s->xll_smpl_in_seg;
+                        int adj = chset->bit_width_adj_per_ch[0][i];
+                        int msb_shift = bits;
+                        unsigned j;
+
+                        if (adj > 0)
+                            msb_shift += adj - 1;
+
+                        for (j = 0; j < s->xll_smpl_in_seg; j++)
+                            sample_buf[j] = (sample_buf[j] << msb_shift) +
+                                            (get_bits(gb, bits) << adj);
+
+                        done += bits * s->xll_smpl_in_seg;
+                    }
+                }
+                if (done > 8 * chset->lsb_fsize[0]) {
+                    av_log(s->avctx, AV_LOG_ERROR,
+                           "chset lsb exceeds lsb_size\n");
+                    return AVERROR_INVALIDDATA;
+                }
+            }
+
+            /* Store output. */
+            for (i = 0; i < chset->channels; i++) {
+                int *sample_buf = s->xll_sample_buf +
+                                  (in_channel + i) * s->xll_smpl_in_seg;
+                int shift = 1 - chset->bit_resolution;
+                int out_channel = chset->orig_chan_order[0][i];
+                float *out;
+
+                /* XLL uses the channel order C, L, R, and we want L,
+                 * R, C. FIXME: Generalize. */
+                if (chset->ch_mask_enabled &&
+                    (chset->ch_mask & 7) == 7 && out_channel < 3)
+                    out_channel = out_channel ? out_channel - 1 : 2;
+
+                out_channel += in_channel;
+                if (out_channel >= s->avctx->channels)
+                    continue;
+
+                out  = (float *) frame->extended_data[out_channel];
+                out += seg * s->xll_smpl_in_seg;
+
+                /* NOTE: A one bit means residual encoding is *not* used. */
+                if ((chset->residual_encode >> i) & 1) {
+                    /* Replace channel samples.
+                     * FIXME: Most likely not the right thing to do. */
+                    for (j = 0; j < s->xll_smpl_in_seg; j++)
+                        out[j] = ldexpf(sample_buf[j], shift);
+                } else {
+                    /* Add residual signal to core channel */
+                    for (j = 0; j < s->xll_smpl_in_seg; j++)
+                        out[j] += ldexpf(sample_buf[j], shift);
+                }
+            }
+
+            if (chset->downmix_coeff_code_embedded &&
+                !chset->primary_ch_set && chset->hier_chset) {
+                /* Undo hierarchical downmix of earlier channels. */
+                unsigned mix_channel;
+                for (mix_channel = 0; mix_channel < in_channel; mix_channel++) {
+                    float *mix_buf;
+                    const int *col;
+                    float coeff;
+                    unsigned row;
+                    /* Similar channel reorder C, L, R vs L, R, C reorder. */
+                    if (chset->ch_mask_enabled &&
+                        (chset->ch_mask & 7) == 7 && mix_channel < 3)
+                        mix_buf = (float *) frame->extended_data[mix_channel ? mix_channel - 1 : 2];
+                    else
+                        mix_buf = (float *) frame->extended_data[mix_channel];
+
+                    mix_buf += seg * s->xll_smpl_in_seg;
+                    col = &chset->downmix_coeffs[mix_channel * (chset->channels + 1)];
+
+                    /* Scale */
+                    coeff = ldexpf(col[0], -16);
+                    for (j = 0; j < s->xll_smpl_in_seg; j++)
+                        mix_buf[j] *= coeff;
+
+                    for (row = 0;
+                         row < chset->channels && in_channel + row < s->avctx->channels;
+                         row++)
+                        if (col[row + 1]) {
+                            const float *new_channel =
+                                (const float *) frame->extended_data[in_channel + row];
+                            new_channel += seg * s->xll_smpl_in_seg;
+                            coeff        = ldexpf(col[row + 1], -15);
+                            for (j = 0; j < s->xll_smpl_in_seg; j++)
+                                mix_buf[j] -= coeff * new_channel[j];
+                        }
+                }
+            }
+
+next_chset:
+            in_channel += chset->channels;
+            /* Skip to next channel set using the NAVI info. */
+            i = get_bits_count(gb);
+            if (i > end_pos) {
+                av_log(s->avctx, AV_LOG_ERROR,
+                       "chset data exceeds NAVI size\n");
+                return AVERROR_INVALIDDATA;
+            }
+            if (i < end_pos)
+                skip_bits_long(gb, end_pos - i);
+        }
+    }
+    return 0;
+}