FFmpeg/libavcodec/takdec.c

/*
 * TAK decoder
 * Copyright (c) 2012 Paul B Mahol
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

/**
 * @file
 * TAK (Tom's lossless Audio Kompressor) decoder
 * @author Paul B Mahol
 */

#include "tak.h"
#include "avcodec.h"
#include "unary.h"
#include "dsputil.h"

#define MAX_SUBFRAMES   8                       ///< max number of subframes per channel
#define MAX_PREDICTORS  256

typedef struct MCDParam {
    int8_t     present;                         ///< is decorrelation parameters available for this channel
    int8_t     index;                           ///< index into array of decorrelation types
    int8_t     chan1;
    int8_t     chan2;
} MCDParam;

typedef struct TAKDecContext {
    AVCodecContext *avctx;                      ///< parent AVCodecContext
    AVFrame        frame;                       ///< AVFrame for decoded output
    DSPContext     dsp;
    TAKStreamInfo  ti;
    GetBitContext  gb;                          ///< bitstream reader initialized to start at the current frame

    int            nb_samples;                  ///< number of samples in the current frame
    int32_t        *decode_buffer;
    int            decode_buffer_size;
    int32_t        *decoded[TAK_MAX_CHANNELS];  ///< decoded samples for each channel

    int8_t         lpc_mode[TAK_MAX_CHANNELS];
    int8_t         sample_shift[TAK_MAX_CHANNELS];  ///< shift applied to every sample in the channel
    int32_t        xred;
    int            size;
    int            ared;
    int            filter_order;
    int16_t        predictors[MAX_PREDICTORS];
    int            nb_subframes;                ///< number of subframes in the current frame
    int16_t        subframe_len[MAX_SUBFRAMES]; ///< subframe length in samples
    int            subframe_scale;

    int8_t         dmode;                       ///< channel decorrelation type in the current frame
    int8_t         dshift;
    int16_t        dfactor;
    int8_t         dval1;
    int8_t         dval2;

    MCDParam       mcdparams[TAK_MAX_CHANNELS]; ///< multichannel decorrelation parameters

    int            wlength;
    int            uval;
    int            rval;
    int8_t         coding_mode[128];
    DECLARE_ALIGNED(16, int16_t, filter)[MAX_PREDICTORS];
    DECLARE_ALIGNED(16, int16_t, residues)[544];
} TAKDecContext;

static const int8_t mc_dmodes[] = {
    1, 3, 4, 6,
};

static const uint16_t predictor_sizes[] = {
    4, 8, 12, 16, 24, 32, 48, 64, 80, 96, 128, 160, 192, 224, 256, 0,
};

static const struct CParam {
    int        init;
    int        escape;
    int        scale;
    int        aescape;
    int        bias;
} xcodes[50] = {
    { 0x01, 0x0000001, 0x0000001, 0x0000003, 0x0000008 },
    { 0x02, 0x0000003, 0x0000001, 0x0000007, 0x0000006 },
    { 0x03, 0x0000005, 0x0000002, 0x000000E, 0x000000D },
    { 0x03, 0x0000003, 0x0000003, 0x000000D, 0x0000018 },
    { 0x04, 0x000000B, 0x0000004, 0x000001C, 0x0000019 },
    { 0x04, 0x0000006, 0x0000006, 0x000001A, 0x0000030 },
    { 0x05, 0x0000016, 0x0000008, 0x0000038, 0x0000032 },
    { 0x05, 0x000000C, 0x000000C, 0x0000034, 0x0000060 },
    { 0x06, 0x000002C, 0x0000010, 0x0000070, 0x0000064 },
    { 0x06, 0x0000018, 0x0000018, 0x0000068, 0x00000C0 },
    { 0x07, 0x0000058, 0x0000020, 0x00000E0, 0x00000C8 },
    { 0x07, 0x0000030, 0x0000030, 0x00000D0, 0x0000180 },
    { 0x08, 0x00000B0, 0x0000040, 0x00001C0, 0x0000190 },
    { 0x08, 0x0000060, 0x0000060, 0x00001A0, 0x0000300 },
    { 0x09, 0x0000160, 0x0000080, 0x0000380, 0x0000320 },
    { 0x09, 0x00000C0, 0x00000C0, 0x0000340, 0x0000600 },
    { 0x0A, 0x00002C0, 0x0000100, 0x0000700, 0x0000640 },
    { 0x0A, 0x0000180, 0x0000180, 0x0000680, 0x0000C00 },
    { 0x0B, 0x0000580, 0x0000200, 0x0000E00, 0x0000C80 },
    { 0x0B, 0x0000300, 0x0000300, 0x0000D00, 0x0001800 },
    { 0x0C, 0x0000B00, 0x0000400, 0x0001C00, 0x0001900 },
    { 0x0C, 0x0000600, 0x0000600, 0x0001A00, 0x0003000 },
    { 0x0D, 0x0001600, 0x0000800, 0x0003800, 0x0003200 },
    { 0x0D, 0x0000C00, 0x0000C00, 0x0003400, 0x0006000 },
    { 0x0E, 0x0002C00, 0x0001000, 0x0007000, 0x0006400 },
    { 0x0E, 0x0001800, 0x0001800, 0x0006800, 0x000C000 },
    { 0x0F, 0x0005800, 0x0002000, 0x000E000, 0x000C800 },
    { 0x0F, 0x0003000, 0x0003000, 0x000D000, 0x0018000 },
    { 0x10, 0x000B000, 0x0004000, 0x001C000, 0x0019000 },
    { 0x10, 0x0006000, 0x0006000, 0x001A000, 0x0030000 },
    { 0x11, 0x0016000, 0x0008000, 0x0038000, 0x0032000 },
    { 0x11, 0x000C000, 0x000C000, 0x0034000, 0x0060000 },
    { 0x12, 0x002C000, 0x0010000, 0x0070000, 0x0064000 },
    { 0x12, 0x0018000, 0x0018000, 0x0068000, 0x00C0000 },
    { 0x13, 0x0058000, 0x0020000, 0x00E0000, 0x00C8000 },
    { 0x13, 0x0030000, 0x0030000, 0x00D0000, 0x0180000 },
    { 0x14, 0x00B0000, 0x0040000, 0x01C0000, 0x0190000 },
    { 0x14, 0x0060000, 0x0060000, 0x01A0000, 0x0300000 },
    { 0x15, 0x0160000, 0x0080000, 0x0380000, 0x0320000 },
    { 0x15, 0x00C0000, 0x00C0000, 0x0340000, 0x0600000 },
    { 0x16, 0x02C0000, 0x0100000, 0x0700000, 0x0640000 },
    { 0x16, 0x0180000, 0x0180000, 0x0680000, 0x0C00000 },
    { 0x17, 0x0580000, 0x0200000, 0x0E00000, 0x0C80000 },
    { 0x17, 0x0300000, 0x0300000, 0x0D00000, 0x1800000 },
    { 0x18, 0x0B00000, 0x0400000, 0x1C00000, 0x1900000 },
    { 0x18, 0x0600000, 0x0600000, 0x1A00000, 0x3000000 },
    { 0x19, 0x1600000, 0x0800000, 0x3800000, 0x3200000 },
    { 0x19, 0x0C00000, 0x0C00000, 0x3400000, 0x6000000 },
    { 0x1A, 0x2C00000, 0x1000000, 0x7000000, 0x6400000 },
    { 0x1A, 0x1800000, 0x1800000, 0x6800000, 0xC000000 },
};

static int tak_set_bps(AVCodecContext *avctx, int bps)
{
    switch (bps) {
    case 8:
        avctx->sample_fmt = AV_SAMPLE_FMT_U8P;
        break;
    case 16:
        avctx->sample_fmt = AV_SAMPLE_FMT_S16P;
        break;
    case 24:
        avctx->sample_fmt = AV_SAMPLE_FMT_S32P;
        break;
    default:
        av_log(avctx, AV_LOG_ERROR, "invalid/unsupported bits per sample\n");
        return AVERROR_INVALIDDATA;
    }

    return 0;
}

static int get_shift(int sample_rate)
{
    int shift;

    if (sample_rate < 11025)
        shift = 3;
    else if (sample_rate < 22050)
        shift = 2;
    else if (sample_rate < 44100)
        shift = 1;
    else
        shift = 0;

    return shift;
}

static int get_scale(int sample_rate, int shift)
{
    return FFALIGN(sample_rate + 511 >> 9, 4) << shift;
}

static av_cold int tak_decode_init(AVCodecContext *avctx)
{
    TAKDecContext *s = avctx->priv_data;
    int ret;

    ff_tak_init_crc();
    ff_dsputil_init(&s->dsp, avctx);

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

    s->uval = get_scale(avctx->sample_rate, get_shift(avctx->sample_rate));
    s->subframe_scale = get_scale(avctx->sample_rate, 1);

    if ((ret = tak_set_bps(avctx, avctx->bits_per_coded_sample)) < 0)
        return ret;

    return 0;
}

static int get_code(GetBitContext *gb, int nbits)
{
    if (nbits == 1) {
        skip_bits1(gb);
        return 0;
    } else {
        return get_sbits(gb, nbits);
    }
}

static void decode_lpc(int32_t *coeffs, int mode, int length)
{
    int i, a1, a2, a3, a4, a5;

    if (length < 2)
        return;

    if (mode == 1) {
        a1 = *coeffs++;
        for (i = 0; i < (length - 1 >> 1); i++) {
            *coeffs   += a1;
            coeffs[1] += *coeffs;
            a1      = coeffs[1];
            coeffs    += 2;
        }
        if ((length - 1) & 1)
            *coeffs += a1;
    } else if (mode == 2) {
        a1     = coeffs[1];
        a2     = a1 + *coeffs;
        coeffs[1] = a2;
        if (length > 2) {
            coeffs += 2;
            for (i = 0; i < (length - 2 >> 1); i++) {
                a3     = *coeffs + a1;
                a4     = a3 + a2;
                *coeffs   = a4;
                a1     = coeffs[1] + a3;
                a2     = a1 + a4;
                coeffs[1] = a2;
                coeffs   += 2;
            }
            if (length & 1)
                *coeffs  += a1 + a2;
        }
    } else if (mode == 3) {
        a1     = coeffs[1];
        a2     = a1 + *coeffs;
        coeffs[1] = a2;
        if (length > 2) {
            a3   = coeffs[2];
            a4   = a3 + a1;
            a5   = a4 + a2;
            coeffs += 3;
            for (i = 0; i < length - 3; i++) {
                a3  += *coeffs;
                a4  += a3;
                a5  += a4;
                *coeffs = a5;
                coeffs++;
            }
        }
    }
}

static int decode_segment(TAKDecContext *s, int8_t value, int32_t *dst, int len)
{
    GetBitContext *gb = &s->gb;

    if (!value) {
        memset(dst, 0, len * 4);
    } else {
        int x, y, z, i = 0;

        value--;
        do {
            while (1) {
                x = get_bits_long(gb, xcodes[value].init);
                if (x >= xcodes[value].escape)
                    break;
                dst[i++] = (x >> 1) ^ -(x & 1);
                if (i >= len)
                    return 0;
            }

            y = get_bits1(gb);
            x = (y << xcodes[value].init) | x;
            if (x >= xcodes[value].aescape) {
                int c = get_unary(gb, 1, 9);

                if (c == 9) {
                    int d;

                    z = x + xcodes[value].bias;
                    d = get_bits(gb, 3);
                    if (d == 7) {
                        d = get_bits(gb, 5) + 7;
                        if (d > 29)
                            return AVERROR_INVALIDDATA;
                    }
                    if (d)
                        z += xcodes[value].scale * (get_bits_long(gb, d) + 1);
                } else {
                    z = xcodes[value].scale * c + x - xcodes[value].escape;
                }
            } else {
                z = x - (xcodes[value].escape & -y);
            }
            dst[i++] = (z >> 1) ^ -(z & 1);
        } while (i < len);
    }

    return 0;
}

static int xget(TAKDecContext *s, int d, int q)
{
    int x;

    x = d / q;

    s->rval = d - (x * q);

    if (s->rval < q / 2) {
        s->rval += q;
    } else {
        x++;
    }

    if (x <= 1 || x > 128)
        return -1;

    return x;
}

static int get_len(TAKDecContext *s, int b)
{
    if (b >= s->wlength - 1)
        return s->rval;
    else
        return s->uval;
}

static int decode_coeffs(TAKDecContext *s, int32_t *dst, int length)
{
    GetBitContext *gb = &s->gb;
    int i, v, ret;

    if (length > s->nb_samples)
        return AVERROR_INVALIDDATA;

    if (get_bits1(gb)) {
        if ((s->wlength = xget(s, length, s->uval)) < 0)
            return AVERROR_INVALIDDATA;

        s->coding_mode[0] = v = get_bits(gb, 6);
        if (s->coding_mode[0] > FF_ARRAY_ELEMS(xcodes))
            return AVERROR_INVALIDDATA;

        for (i = 1; i < s->wlength; i++) {
            int c = get_unary(gb, 1, 6);

            if (c > 5) {
                v = get_bits(gb, 6);
            } else if (c > 2) {
                int t = get_bits1(gb);

                v += (-t ^ (c - 1)) + t;
            } else {
                v += (-(c & 1) ^ (((c & 1) + c) >> 1)) + (c & 1);
            }

            if (v > FF_ARRAY_ELEMS(xcodes))
                return AVERROR_INVALIDDATA;
            s->coding_mode[i] = v;
        }

        i = 0;
        while (i < s->wlength) {
            int len = 0;

            v = s->coding_mode[i];
            do {
                len += get_len(s, i);
                i++;

                if (i == s->wlength)
                    break;
            } while (v == s->coding_mode[i]);

            if ((ret = decode_segment(s, v, dst, len)) < 0)
                return ret;
            dst += len;
        }
    } else {
        v = get_bits(gb, 6);
        if (v > FF_ARRAY_ELEMS(xcodes))
            return AVERROR_INVALIDDATA;
        if ((ret = decode_segment(s, v, dst, length)) < 0)
            return ret;
    }

    return 0;
}

static int get_b(GetBitContext *gb)
{
    if (get_bits1(gb))
        return get_bits(gb, 4) + 1;
    else
        return 0;
}

static int decode_subframe(TAKDecContext *s, int32_t *ptr, int subframe_size,
                           int prev_subframe_size)
{
    GetBitContext  *gb = &s->gb;
    int tmp, x, y, i, j, ret = 0;
    int tfilter[MAX_PREDICTORS];

    if (get_bits1(gb)) {
        s->filter_order = predictor_sizes[get_bits(gb, 4)];

        if (prev_subframe_size > 0 && get_bits1(gb)) {
            if (s->filter_order > prev_subframe_size)
                return AVERROR_INVALIDDATA;

            ptr           -= s->filter_order;
            subframe_size += s->filter_order;

            if (s->filter_order > subframe_size)
                return AVERROR_INVALIDDATA;
        } else {
            int lpc;

            if (s->filter_order > subframe_size)
                return AVERROR_INVALIDDATA;

            lpc = get_bits(gb, 2);
            if (lpc > 2)
                return AVERROR_INVALIDDATA;

            if ((ret = decode_coeffs(s, ptr, s->filter_order)) < 0)
                return ret;

            decode_lpc(ptr, lpc, s->filter_order);
        }

        s->xred = get_b(gb);
        s->size = get_bits1(gb) + 5;

        if (get_bits1(gb)) {
            s->ared = get_bits(gb, 3) + 1;
            if (s->ared > 7)
                return AVERROR_INVALIDDATA;
        } else {
            s->ared = 0;
        }
        s->predictors[0] = get_code(gb, 10);
        s->predictors[1] = get_code(gb, 10);
        s->predictors[2] = get_code(gb, s->size + 1) << (9 - s->size);
        s->predictors[3] = get_code(gb, s->size + 1) << (9 - s->size);
        if (s->filter_order > 4) {
            tmp = s->size + 1 - get_bits1(gb);

            for (i = 4; i < s->filter_order; i++) {
                if (!(i & 3))
                    x = tmp - get_bits(gb, 2);
                s->predictors[i] = get_code(gb, x) << (9 - s->size);
            }
        }

        tfilter[0] = s->predictors[0] << 6;
        for (i = 1; i < s->filter_order; i++) {
            int32_t *p1 = &tfilter[0];
            int32_t *p2 = &tfilter[i - 1];

            for (j = 0; j < (i + 1) / 2; j++) {
                x     = *p1 + (s->predictors[i] * *p2 + 256 >> 9);
                *p2  += s->predictors[i] * *p1 + 256 >> 9;
                *p1++ = x;
                p2--;
            }

            tfilter[i] = s->predictors[i] << 6;
        }

        x = -1 << (32 - (s->ared + 5));
        y =  1 << ((s->ared + 5) - 1);
        for (i = 0, j = s->filter_order - 1; i < s->filter_order / 2; i++, j--) {
            tmp = y + tfilter[j];
            s->filter[j] = -(x & -(y + tfilter[i] >> 31) |
                            (y + tfilter[i]) >> (s->ared + 5));
            s->filter[i] = -(x & -(tmp >> 31) | (tmp >> s->ared + 5));
        }

        if ((ret = decode_coeffs(s, &ptr[s->filter_order],
                                 subframe_size - s->filter_order)) < 0)
            return ret;

        for (i = 0; i < s->filter_order; i++)
            s->residues[i] = *ptr++ >> s->xred;

        y    = FF_ARRAY_ELEMS(s->residues) - s->filter_order;
        x    = subframe_size - s->filter_order;
        while (x > 0) {
            tmp = FFMIN(y, x);

            for (i = 0; i < tmp; i++) {
                int v, w, m;

                v = 1 << (10 - s->ared - 1);
                if (!(s->filter_order & 15)) {
                    v += s->dsp.scalarproduct_int16(&s->residues[i], s->filter,
                                                    s->filter_order);
                } else if (s->filter_order & 4) {
                    for (j = 0; j < s->filter_order; j += 4) {
                        v += s->residues[i + j + 3] * s->filter[j + 3] +
                             s->residues[i + j + 2] * s->filter[j + 2] +
                             s->residues[i + j + 1] * s->filter[j + 1] +
                             s->residues[i + j    ] * s->filter[j    ];
                    }
                } else {
                    for (j = 0; j < s->filter_order; j += 8) {
                        v += s->residues[i + j + 7] * s->filter[j + 7] +
                             s->residues[i + j + 6] * s->filter[j + 6] +
                             s->residues[i + j + 5] * s->filter[j + 5] +
                             s->residues[i + j + 4] * s->filter[j + 4] +
                             s->residues[i + j + 3] * s->filter[j + 3] +
                             s->residues[i + j + 2] * s->filter[j + 2] +
                             s->residues[i + j + 1] * s->filter[j + 1] +
                             s->residues[i + j    ] * s->filter[j    ];
                    }
                }
                m = (-1 << (32 - (10 - s->ared))) & -(v >> 31) | (v >> 10 - s->ared);
                m = av_clip(m, -8192, 8191);
                w = (m << s->xred) - *ptr;
                *ptr++ = w;
                s->residues[s->filter_order + i] = w >> s->xred;
            }

            x -= tmp;
            if (x > 0)
                memcpy(s->residues, &s->residues[y], 2 * s->filter_order);
        }

        emms_c();
    } else {
        ret = decode_coeffs(s, ptr, subframe_size);
    }

    return ret;
}

static int decode_channel(TAKDecContext *s, int chan)
{
    AVCodecContext *avctx = s->avctx;
    GetBitContext  *gb = &s->gb;
    int32_t *dst = s->decoded[chan];
    int i = 0, ret, prev = 0;
    int left = s->nb_samples - 1;

    s->sample_shift[chan] = get_b(gb);
    if (s->sample_shift[chan] >= avctx->bits_per_raw_sample)
        return AVERROR_INVALIDDATA;

    *dst++ = get_code(gb, avctx->bits_per_raw_sample - s->sample_shift[chan]);
    s->lpc_mode[chan] = get_bits(gb, 2);
    s->nb_subframes   = get_bits(gb, 3) + 1;

    if (s->nb_subframes > 1) {
        if (get_bits_left(gb) < (s->nb_subframes - 1) * 6)
            return AVERROR_INVALIDDATA;

        for (; i < s->nb_subframes - 1; i++) {
            int v = get_bits(gb, 6);

            s->subframe_len[i] = (v - prev) * s->subframe_scale;
            if (s->subframe_len[i] <= 0)
                return AVERROR_INVALIDDATA;

            left -= s->subframe_len[i];
            prev  = v;
        }

        if (left <= 0)
            return AVERROR_INVALIDDATA;
    }

    s->subframe_len[i] = left;
    prev = 0;
    for (i = 0; i < s->nb_subframes; i++) {
        if ((ret = decode_subframe(s, dst, s->subframe_len[i], prev)) < 0)
            return ret;
        dst += s->subframe_len[i];
        prev = s->subframe_len[i];
    }

    return 0;
}

static int decorrelate(TAKDecContext *s, int c1, int c2, int length)
{
    GetBitContext  *gb = &s->gb;
    uint32_t *p1 = s->decoded[c1] + 1;
    uint32_t *p2 = s->decoded[c2] + 1;
    int a, b, i, x, tmp;

    if (s->dmode > 3) {
        s->dshift = get_b(gb);
        if (s->dmode > 5) {
            if (get_bits1(gb))
                s->filter_order = 16;
            else
                s->filter_order = 8;

            s->dval1 = get_bits1(gb);
            s->dval2 = get_bits1(gb);

            for (i = 0; i < s->filter_order; i++) {
                if (!(i & 3))
                    x = 14 - get_bits(gb, 3);
                s->filter[i] = get_code(gb, x);
            }
        } else {
            s->dfactor = get_code(gb, 10);
        }
    }

    switch (s->dmode) {
    case 1:
        for (i = 0; i < length; i++, p1++, p2++)
            *p2 += *p1;
        break;
    case 2:
        for (i = 0; i < length; i++, p1++, p2++)
            *p1 = *p2 - *p1;
        break;
    case 3:
        for (i = 0; i < length; i++, p1++, p2++) {
            x   = (*p2 & 1) + 2 * *p1;
            a   = -*p2 + x;
            b   =  *p2 + x;
            *p1 = a & 0x80000000 | (a >> 1);
            *p2 = b & 0x80000000 | (b >> 1);
        }
        break;
    case 4:
        FFSWAP(uint32_t *, p1, p2);
    case 5:
        if (s->dshift)
            tmp = -1 << (32 - s->dshift);
        else
            tmp = 0;

        for (i = 0; i < length; i++, p1++, p2++) {
            x   = s->dfactor * (tmp & -(*p2 >> 31) | (*p2 >> s->dshift)) + 128;
            *p1 = ((-(x >> 31) & 0xFF000000 | (x >> 8)) << s->dshift) - *p1;
        }
        break;
    case 6:
        FFSWAP(uint32_t *, p1, p2);
    case 7:
        if (length < 256)
            return AVERROR_INVALIDDATA;

        a = s->filter_order / 2;
        b = length - (s->filter_order - 1);

        if (s->dval1) {
            for (i = 0; i < a; i++)
                p1[i] += p2[i];
        }

        if (s->dval2) {
            x = a + b;
            for (i = 0; i < length - x; i++)
                p1[x + i] += p2[x + i];
        }

        for (i = 0; i < s->filter_order; i++)
            s->residues[i] = *p2++ >> s->dshift;

        p1 += a;
        x = FF_ARRAY_ELEMS(s->residues) - s->filter_order;
        for (; b > 0; b -= tmp) {
            tmp = FFMIN(b, x);

            for (i = 0; i < tmp; i++)
                s->residues[s->filter_order + i] = *p2++ >> s->dshift;

            for (i = 0; i < tmp; i++) {
                int v, w, m;

                v = 1 << 9;

                if (s->filter_order == 16) {
                    v += s->dsp.scalarproduct_int16(&s->residues[i], s->filter,
                                                    s->filter_order);
                } else {
                    v += s->residues[i + 7] * s->filter[7] +
                         s->residues[i + 6] * s->filter[6] +
                         s->residues[i + 5] * s->filter[5] +
                         s->residues[i + 4] * s->filter[4] +
                         s->residues[i + 3] * s->filter[3] +
                         s->residues[i + 2] * s->filter[2] +
                         s->residues[i + 1] * s->filter[1] +
                         s->residues[i    ] * s->filter[0];
                }

                m = (-1 << 22) & -(v >> 31) | (v >> 10);
                m = av_clip(m, -8192, 8191);
                w = (m << s->dshift) - *p1;
                *p1++ = w;
            }

            memcpy(s->residues, &s->residues[tmp], 2 * s->filter_order);
        }

        emms_c();
        break;
    }

    return 0;
}

static int tak_decode_frame(AVCodecContext *avctx, void *data,
                            int *got_frame_ptr, AVPacket *pkt)
{
    TAKDecContext  *s = avctx->priv_data;
    GetBitContext *gb = &s->gb;
    int chan, i, ret, hsize;
    int32_t *p;

    if (pkt->size < TAK_MIN_FRAME_HEADER_BYTES)
        return AVERROR_INVALIDDATA;

    init_get_bits(gb, pkt->data, pkt->size * 8);

    if ((ret = ff_tak_decode_frame_header(avctx, gb, &s->ti, 0)) < 0)
        return ret;

    if (avctx->err_recognition & AV_EF_CRCCHECK) {
        hsize = get_bits_count(gb) / 8;
        if (ff_tak_check_crc(pkt->data, hsize)) {
            av_log(avctx, AV_LOG_ERROR, "CRC error\n");
            return AVERROR_INVALIDDATA;
        }
    }

    if (s->ti.codec != 2 && s->ti.codec != 4) {
        av_log(avctx, AV_LOG_ERROR, "unsupported codec: %d\n", s->ti.codec);
        return AVERROR_PATCHWELCOME;
    }
    if (s->ti.data_type) {
        av_log(avctx, AV_LOG_ERROR, "unsupported data type: %d\n", s->ti.data_type);
        return AVERROR_INVALIDDATA;
    }
    if (s->ti.codec == 2 && s->ti.channels > 2) {
        av_log(avctx, AV_LOG_ERROR, "invalid number of channels: %d\n", s->ti.channels);
        return AVERROR_INVALIDDATA;
    }
    if (s->ti.channels > 6) {
        av_log(avctx, AV_LOG_ERROR, "unsupported number of channels: %d\n", s->ti.channels);
        return AVERROR_INVALIDDATA;
    }

    if (s->ti.frame_samples <= 0) {
        av_log(avctx, AV_LOG_ERROR, "unsupported/invalid number of samples\n");
        return AVERROR_INVALIDDATA;
    }

    if (s->ti.bps != avctx->bits_per_raw_sample) {
        avctx->bits_per_raw_sample = s->ti.bps;
        if ((ret = tak_set_bps(avctx, avctx->bits_per_raw_sample)) < 0)
            return ret;
    }
    if (s->ti.sample_rate != avctx->sample_rate) {
        avctx->sample_rate = s->ti.sample_rate;
        s->uval = get_scale(avctx->sample_rate, get_shift(avctx->sample_rate));
        s->subframe_scale = get_scale(avctx->sample_rate, 1);
    }
    if (s->ti.ch_layout)
        avctx->channel_layout = s->ti.ch_layout;
    avctx->channels = s->ti.channels;

    s->nb_samples = s->ti.last_frame_samples ? s->ti.last_frame_samples :
                                               s->ti.frame_samples;

    s->frame.nb_samples = s->nb_samples;
    if ((ret = avctx->get_buffer(avctx, &s->frame)) < 0)
        return ret;

    if (avctx->bits_per_raw_sample <= 16) {
        av_fast_malloc(&s->decode_buffer, &s->decode_buffer_size,
                       sizeof(*s->decode_buffer) * FFALIGN(s->nb_samples, 8) *
                       avctx->channels + FF_INPUT_BUFFER_PADDING_SIZE);
        if (!s->decode_buffer)
            return AVERROR(ENOMEM);
        for (chan = 0; chan < avctx->channels; chan++)
            s->decoded[chan] = s->decode_buffer +
                               chan * FFALIGN(s->nb_samples, 8);
    } else {
        for (chan = 0; chan < avctx->channels; chan++)
            s->decoded[chan] = (int32_t *)s->frame.data[chan];
    }

    if (s->nb_samples < 16) {
        for (chan = 0; chan < avctx->channels; chan++) {
            p = s->decoded[chan];
            for (i = 0; i < s->nb_samples; i++)
                *p++ = get_code(gb, avctx->bits_per_raw_sample);
        }
    } else {
        if (s->ti.codec == 2) {
            for (chan = 0; chan < avctx->channels; chan++) {
                if (ret = decode_channel(s, chan))
                    return ret;
            }

            if (avctx->channels == 2) {
                s->nb_subframes = get_bits(gb, 1) + 1;
                if (s->nb_subframes > 1)
                    s->subframe_len[1] = get_bits(gb, 6);

                s->dmode = get_bits(gb, 3);
                if (ret = decorrelate(s, 0, 1, s->nb_samples - 1))
                    return ret;
            }
        } else if (s->ti.codec == 4) {
            if (get_bits1(gb)) {
                int ch_mask = 0;

                chan = get_bits(gb, 4) + 1;
                if (chan > avctx->channels)
                    return AVERROR_INVALIDDATA;

                for (i = 0; i < chan; i++) {
                    int nbit = get_bits(gb, 4);

                    if (nbit >= avctx->channels)
                        return AVERROR_INVALIDDATA;

                    if (ch_mask & 1 << nbit)
                        return AVERROR_INVALIDDATA;

                    s->mcdparams[i].present = get_bits1(gb);
                    if (s->mcdparams[i].present) {
                        s->mcdparams[i].index = get_bits(gb, 2);
                        s->mcdparams[i].chan2 = get_bits(gb, 4);
                        if (s->mcdparams[i].index == 1) {
                            if ((nbit == s->mcdparams[i].chan2) ||
                                (ch_mask & 1 << s->mcdparams[i].chan2))
                                return AVERROR_INVALIDDATA;

                            ch_mask |= 1 << s->mcdparams[i].chan2;
                        } else if (!(ch_mask & 1 << s->mcdparams[i].chan2)) {
                            return AVERROR_INVALIDDATA;
                        }
                    }
                    s->mcdparams[i].chan1 = nbit;

                    ch_mask |= 1 << nbit;
                }
            } else {
                chan = avctx->channels;
                for (i = 0; i < chan; i++) {
                    s->mcdparams[i].present = 0;
                    s->mcdparams[i].chan1   = i;
                }
            }

            for (i = 0; i < chan; i++) {
                if (s->mcdparams[i].present && s->mcdparams[i].index == 1) {
                    if (ret = decode_channel(s, s->mcdparams[i].chan2))
                        return ret;
                }

                if (ret = decode_channel(s, s->mcdparams[i].chan1))
                    return ret;

                if (s->mcdparams[i].present) {
                    s->dmode = mc_dmodes[s->mcdparams[i].index];
                    if (ret = decorrelate(s, s->mcdparams[i].chan2,
                                             s->mcdparams[i].chan1,
                                             s->nb_samples - 1))
                        return ret;
                }
            }
        }

        for (chan = 0; chan < avctx->channels; chan++) {
            p = s->decoded[chan];
            decode_lpc(p, s->lpc_mode[chan], s->nb_samples);

            if (s->sample_shift[chan] > 0) {
                for (i = 0; i < s->nb_samples; i++)
                    *p++ <<= s->sample_shift[chan];
            }
        }
    }

    align_get_bits(gb);
    skip_bits(gb, 24);
    if (get_bits_left(gb) < 0)
        av_log(avctx, AV_LOG_DEBUG, "overread\n");
    else if (get_bits_left(gb) > 0)
        av_log(avctx, AV_LOG_DEBUG, "underread\n");

    if (avctx->err_recognition & AV_EF_CRCCHECK) {
        if (ff_tak_check_crc(pkt->data + hsize,
                             get_bits_count(gb) / 8 - hsize)) {
            av_log(avctx, AV_LOG_ERROR, "CRC error\n");
            return AVERROR_INVALIDDATA;
        }
    }

    // convert to output buffer
    switch (avctx->bits_per_raw_sample) {
    case 8:
        for (chan = 0; chan < avctx->channels; chan++) {
            uint8_t *samples = (uint8_t *)s->frame.data[chan];
            p = s->decoded[chan];
            for (i = 0; i < s->nb_samples; i++, p++)
                *samples++ = *p + 0x80;
        }
        break;
    case 16:
        for (chan = 0; chan < avctx->channels; chan++) {
            int16_t *samples = (int16_t *)s->frame.data[chan];
            p = s->decoded[chan];
            for (i = 0; i < s->nb_samples; i++, p++)
                *samples++ = *p;
        }
        break;
    case 24:
        for (chan = 0; chan < avctx->channels; chan++) {
            int32_t *samples = (int32_t *)s->frame.data[chan];
            for (i = 0; i < s->nb_samples; i++)
                *samples++ <<= 8;
        }
        break;
    }

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

    return pkt->size;
}

static av_cold int tak_decode_close(AVCodecContext *avctx)
{
    TAKDecContext *s = avctx->priv_data;

    av_freep(&s->decode_buffer);

    return 0;
}

AVCodec ff_tak_decoder = {
    .name           = "tak",
    .type           = AVMEDIA_TYPE_AUDIO,
    .id             = AV_CODEC_ID_TAK,
    .priv_data_size = sizeof(TAKDecContext),
    .init           = tak_decode_init,
    .close          = tak_decode_close,
    .decode         = tak_decode_frame,
    .capabilities   = CODEC_CAP_DR1,
    .long_name      = NULL_IF_CONFIG_SMALL("TAK (Tom's lossless Audio Kompressor)"),
};