FFmpeg/libavcodec/huffyuvdec.c

/*
 * huffyuv decoder
 *
 * Copyright (c) 2002-2003 Michael Niedermayer <michaelni@gmx.at>
 *
 * see http://www.pcisys.net/~melanson/codecs/huffyuv.txt for a description of
 * the algorithm used
 *
 * 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
 */

/**
 * @file
 * huffyuv decoder
 */

#include "avcodec.h"
#include "get_bits.h"
#include "huffyuv.h"
#include "huffyuvdsp.h"
#include "thread.h"

#define classic_shift_luma_table_size 42
static const unsigned char classic_shift_luma[classic_shift_luma_table_size + FF_INPUT_BUFFER_PADDING_SIZE] = {
    34, 36, 35, 69, 135, 232,   9, 16, 10, 24,  11,  23,  12,  16, 13, 10,
    14,  8, 15,  8,  16,   8,  17, 20, 16, 10, 207, 206, 205, 236, 11,  8,
    10, 21,  9, 23,   8,   8, 199, 70, 69, 68,   0
};

#define classic_shift_chroma_table_size 59
static const unsigned char classic_shift_chroma[classic_shift_chroma_table_size + FF_INPUT_BUFFER_PADDING_SIZE] = {
    66, 36,  37,  38, 39, 40,  41,  75,  76,  77, 110, 239, 144, 81, 82,  83,
    84, 85, 118, 183, 56, 57,  88,  89,  56,  89, 154,  57,  58, 57, 26, 141,
    57, 56,  58,  57, 58, 57, 184, 119, 214, 245, 116,  83,  82, 49, 80,  79,
    78, 77,  44,  75, 41, 40,  39,  38,  37,  36,  34,  0
};

static const unsigned char classic_add_luma[256] = {
     3,  9,  5, 12, 10, 35, 32, 29, 27, 50, 48, 45, 44, 41, 39, 37,
    73, 70, 68, 65, 64, 61, 58, 56, 53, 50, 49, 46, 44, 41, 38, 36,
    68, 65, 63, 61, 58, 55, 53, 51, 48, 46, 45, 43, 41, 39, 38, 36,
    35, 33, 32, 30, 29, 27, 26, 25, 48, 47, 46, 44, 43, 41, 40, 39,
    37, 36, 35, 34, 32, 31, 30, 28, 27, 26, 24, 23, 22, 20, 19, 37,
    35, 34, 33, 31, 30, 29, 27, 26, 24, 23, 21, 20, 18, 17, 15, 29,
    27, 26, 24, 22, 21, 19, 17, 16, 14, 26, 25, 23, 21, 19, 18, 16,
    15, 27, 25, 23, 21, 19, 17, 16, 14, 26, 25, 23, 21, 18, 17, 14,
    12, 17, 19, 13,  4,  9,  2, 11,  1,  7,  8,  0, 16,  3, 14,  6,
    12, 10,  5, 15, 18, 11, 10, 13, 15, 16, 19, 20, 22, 24, 27, 15,
    18, 20, 22, 24, 26, 14, 17, 20, 22, 24, 27, 15, 18, 20, 23, 25,
    28, 16, 19, 22, 25, 28, 32, 36, 21, 25, 29, 33, 38, 42, 45, 49,
    28, 31, 34, 37, 40, 42, 44, 47, 49, 50, 52, 54, 56, 57, 59, 60,
    62, 64, 66, 67, 69, 35, 37, 39, 40, 42, 43, 45, 47, 48, 51, 52,
    54, 55, 57, 59, 60, 62, 63, 66, 67, 69, 71, 72, 38, 40, 42, 43,
    46, 47, 49, 51, 26, 28, 30, 31, 33, 34, 18, 19, 11, 13,  7,  8,
};

static const unsigned char classic_add_chroma[256] = {
     3,    1,   2,   2,   2,   2,   3,   3,   7,   5,   7,   5,   8,   6,  11,   9,
     7,   13,  11,  10,   9,   8,   7,   5,   9,   7,   6,   4,   7,   5,   8,   7,
     11,   8,  13,  11,  19,  15,  22,  23,  20,  33,  32,  28,  27,  29,  51,  77,
     43,  45,  76,  81,  46,  82,  75,  55,  56, 144,  58,  80,  60,  74, 147,  63,
    143,  65,  66,  67,  68,  69,  70,  71,  72,  73,  74,  75,  76,  77,  78,  79,
     80,  81,  82,  83,  84,  85,  86,  87,  88,  89,  90,  91,  27,  30,  21,  22,
     17,  14,   5,   6, 100,  54,  47,  50,  51,  53, 106, 107, 108, 109, 110, 111,
    112, 113, 114, 115,   4, 117, 118,  92,  94, 121, 122,   3, 124, 103,   2,   1,
      0, 129, 130, 131, 120, 119, 126, 125, 136, 137, 138, 139, 140, 141, 142, 134,
    135, 132, 133, 104,  64, 101,  62,  57, 102,  95,  93,  59,  61,  28,  97,  96,
     52,  49,  48,  29,  32,  25,  24,  46,  23,  98,  45,  44,  43,  20,  42,  41,
     19,  18,  99,  40,  15,  39,  38,  16,  13,  12,  11,  37,  10,   9,   8,  36,
      7, 128, 127, 105, 123, 116,  35,  34,  33, 145,  31,  79,  42, 146,  78,  26,
     83,  48,  49,  50,  44,  47,  26,  31,  30,  18,  17,  19,  21,  24,  25,  13,
     14,  16,  17,  18,  20,  21,  12,  14,  15,   9,  10,   6,   9,   6,   5,   8,
      6,  12,   8,  10,   7,   9,   6,   4,   6,   2,   2,   3,   3,   3,   3,   2,
};

static int read_len_table(uint8_t *dst, GetBitContext *gb)
{
    int i, val, repeat;

    for (i = 0; i < 256;) {
        repeat = get_bits(gb, 3);
        val    = get_bits(gb, 5);
        if (repeat == 0)
            repeat = get_bits(gb, 8);
        if (i + repeat > 256 || get_bits_left(gb) < 0) {
            av_log(NULL, AV_LOG_ERROR, "Error reading huffman table\n");
            return AVERROR_INVALIDDATA;
        }
        while (repeat--)
            dst[i++] = val;
    }
    return 0;
}

static int generate_joint_tables(HYuvContext *s)
{
    uint16_t symbols[1 << VLC_BITS];
    uint16_t bits[1 << VLC_BITS];
    uint8_t len[1 << VLC_BITS];
    int ret;

    if (s->bitstream_bpp < 24) {
        int p, i, y, u;
        for (p = 0; p < 3; p++) {
            for (i = y = 0; y < 256; y++) {
                int len0  = s->len[0][y];
                int limit = VLC_BITS - len0;
                if (limit <= 0)
                    continue;
                for (u = 0; u < 256; u++) {
                    int len1 = s->len[p][u];
                    if (len1 > limit)
                        continue;
                    len[i]     = len0 + len1;
                    bits[i]    = (s->bits[0][y] << len1) + s->bits[p][u];
                    symbols[i] = (y << 8) + u;
                    if (symbols[i] != 0xffff) // reserved to mean "invalid"
                        i++;
                }
            }
            ff_free_vlc(&s->vlc[3 + p]);
            if ((ret = ff_init_vlc_sparse(&s->vlc[3 + p], VLC_BITS, i, len, 1, 1,
                                          bits, 2, 2, symbols, 2, 2, 0)) < 0)
                return ret;
        }
    } else {
        uint8_t (*map)[4] = (uint8_t(*)[4]) s->pix_bgr_map;
        int i, b, g, r, code;
        int p0 = s->decorrelate;
        int p1 = !s->decorrelate;
        /* Restrict the range to +/-16 because that's pretty much guaranteed
         * to cover all the combinations that fit in 11 bits total, and it
         *  does not matter if we miss a few rare codes. */
        for (i = 0, g = -16; g < 16; g++) {
            int len0   = s->len[p0][g & 255];
            int limit0 = VLC_BITS - len0;
            if (limit0 < 2)
                continue;
            for (b = -16; b < 16; b++) {
                int len1   = s->len[p1][b & 255];
                int limit1 = limit0 - len1;
                if (limit1 < 1)
                    continue;
                code = (s->bits[p0][g & 255] << len1) + s->bits[p1][b & 255];
                for (r = -16; r < 16; r++) {
                    int len2 = s->len[2][r & 255];
                    if (len2 > limit1)
                        continue;
                    len[i]  = len0 + len1 + len2;
                    bits[i] = (code << len2) + s->bits[2][r & 255];
                    if (s->decorrelate) {
                        map[i][G] = g;
                        map[i][B] = g + b;
                        map[i][R] = g + r;
                    } else {
                        map[i][B] = g;
                        map[i][G] = b;
                        map[i][R] = r;
                    }
                    i++;
                }
            }
        }
        ff_free_vlc(&s->vlc[3]);
        if ((ret = init_vlc(&s->vlc[3], VLC_BITS, i, len, 1, 1,
                            bits, 2, 2, 0)) < 0)
            return ret;
    }
    return 0;
}

static int read_huffman_tables(HYuvContext *s, const uint8_t *src, int length)
{
    GetBitContext gb;
    int i, ret;

    if ((ret = init_get_bits(&gb, src, length * 8)) < 0)
        return ret;

    for (i = 0; i < 3; i++) {
        if ((ret = read_len_table(s->len[i], &gb)) < 0)
            return ret;
        if ((ret = ff_huffyuv_generate_bits_table(s->bits[i], s->len[i])) < 0)
            return ret;
        ff_free_vlc(&s->vlc[i]);
        if ((ret = init_vlc(&s->vlc[i], VLC_BITS, 256, s->len[i], 1, 1,
                            s->bits[i], 4, 4, 0)) < 0)
            return ret;
    }

    if ((ret = generate_joint_tables(s)) < 0)
        return ret;

    return (get_bits_count(&gb) + 7) / 8;
}

static int read_old_huffman_tables(HYuvContext *s)
{
    GetBitContext gb;
    int i, ret;

    if ((ret = init_get_bits(&gb, classic_shift_luma,
                             classic_shift_luma_table_size * 8)) < 0)
        return ret;
    if ((ret = read_len_table(s->len[0], &gb)) < 0)
        return ret;

    if ((ret = init_get_bits(&gb, classic_shift_chroma,
                             classic_shift_chroma_table_size * 8)) < 0)
        return ret;
    if ((ret = read_len_table(s->len[1], &gb)) < 0)
        return ret;

    for (i = 0; i < 256; i++)
        s->bits[0][i] = classic_add_luma[i];
    for (i = 0; i < 256; i++)
        s->bits[1][i] = classic_add_chroma[i];

    if (s->bitstream_bpp >= 24) {
        memcpy(s->bits[1], s->bits[0], 256 * sizeof(uint32_t));
        memcpy(s->len[1], s->len[0], 256 * sizeof(uint8_t));
    }
    memcpy(s->bits[2], s->bits[1], 256 * sizeof(uint32_t));
    memcpy(s->len[2], s->len[1], 256 * sizeof(uint8_t));

    for (i = 0; i < 3; i++) {
        ff_free_vlc(&s->vlc[i]);
        if ((ret = init_vlc(&s->vlc[i], VLC_BITS, 256, s->len[i], 1, 1,
                            s->bits[i], 4, 4, 0)) < 0)
            return ret;
    }

    if ((ret = generate_joint_tables(s)) < 0)
        return ret;

    return 0;
}

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

    ff_huffyuv_common_init(avctx);
    ff_huffyuvdsp_init(&s->hdsp);
    memset(s->vlc, 0, 3 * sizeof(VLC));

    s->interlaced = s->height > 288;
    s->bgr32      = 1;

    if (avctx->extradata_size) {
        if ((avctx->bits_per_coded_sample & 7) &&
            avctx->bits_per_coded_sample != 12)
            s->version = 1; // do such files exist at all?
        else
            s->version = 2;
    } else
        s->version = 0;

    if (s->version == 2) {
        int method, interlace;

        if (avctx->extradata_size < 4)
            return AVERROR_INVALIDDATA;

        method           = avctx->extradata[0];
        s->decorrelate   = method & 64 ? 1 : 0;
        s->predictor     = method & 63;
        s->bitstream_bpp = avctx->extradata[1];
        if (s->bitstream_bpp == 0)
            s->bitstream_bpp = avctx->bits_per_coded_sample & ~7;
        interlace     = (avctx->extradata[2] & 0x30) >> 4;
        s->interlaced = (interlace == 1) ? 1 : (interlace == 2) ? 0 : s->interlaced;
        s->context    = avctx->extradata[2] & 0x40 ? 1 : 0;

        if ((ret = read_huffman_tables(s, avctx->extradata + 4,
                                       avctx->extradata_size - 4)) < 0)
            return ret;
    } else {
        switch (avctx->bits_per_coded_sample & 7) {
        case 1:
            s->predictor   = LEFT;
            s->decorrelate = 0;
            break;
        case 2:
            s->predictor   = LEFT;
            s->decorrelate = 1;
            break;
        case 3:
            s->predictor   = PLANE;
            s->decorrelate = avctx->bits_per_coded_sample >= 24;
            break;
        case 4:
            s->predictor   = MEDIAN;
            s->decorrelate = 0;
            break;
        default:
            s->predictor   = LEFT; // OLD
            s->decorrelate = 0;
            break;
        }
        s->bitstream_bpp = avctx->bits_per_coded_sample & ~7;
        s->context       = 0;

        if ((ret = read_old_huffman_tables(s)) < 0)
            return ret;
    }

    switch (s->bitstream_bpp) {
    case 12:
        avctx->pix_fmt = AV_PIX_FMT_YUV420P;
        break;
    case 16:
        if (s->yuy2)
            avctx->pix_fmt = AV_PIX_FMT_YUYV422;
        else
            avctx->pix_fmt = AV_PIX_FMT_YUV422P;
        break;
    case 24:
    case 32:
        if (s->bgr32)
            avctx->pix_fmt = AV_PIX_FMT_RGB32;
        else
            avctx->pix_fmt = AV_PIX_FMT_BGR24;
        break;
    default:
        return AVERROR_INVALIDDATA;
    }

    if ((ret = ff_huffyuv_alloc_temp(s)) < 0)
        return ret;

    return 0;
}

static av_cold int decode_init_thread_copy(AVCodecContext *avctx)
{
    HYuvContext *s = avctx->priv_data;
    int i, ret;

    if ((ret = ff_huffyuv_alloc_temp(s)) < 0)
        return ret;

    for (i = 0; i < 6; i++)
        s->vlc[i].table = NULL;

    if (s->version == 2) {
        if ((ret = read_huffman_tables(s, avctx->extradata + 4,
                                       avctx->extradata_size)) < 0)
            return ret;
    } else {
        if ((ret = read_old_huffman_tables(s)) < 0)
            return ret;
    }

    return 0;
}

/* TODO instead of restarting the read when the code isn't in the first level
 * of the joint table, jump into the 2nd level of the individual table. */
#define READ_2PIX(dst0, dst1, plane1)                                   \
    {                                                                   \
        uint16_t code = get_vlc2(&s->gb, s->vlc[3 + plane1].table,      \
                                 VLC_BITS, 1);                          \
        if (code != 0xffff) {                                           \
            dst0 = code >> 8;                                           \
            dst1 = code;                                                \
        } else {                                                        \
            dst0 = get_vlc2(&s->gb, s->vlc[0].table, VLC_BITS, 3);      \
            dst1 = get_vlc2(&s->gb, s->vlc[plane1].table, VLC_BITS, 3); \
        }                                                               \
    }

static void decode_422_bitstream(HYuvContext *s, int count)
{
    int i;

    count /= 2;

    if (count >= (get_bits_left(&s->gb)) / (31 * 4)) {
        for (i = 0; i < count && get_bits_left(&s->gb) > 0; i++) {
            READ_2PIX(s->temp[0][2 * i],     s->temp[1][i], 1);
            READ_2PIX(s->temp[0][2 * i + 1], s->temp[2][i], 2);
        }
    } else {
        for (i = 0; i < count; i++) {
            READ_2PIX(s->temp[0][2 * i],     s->temp[1][i], 1);
            READ_2PIX(s->temp[0][2 * i + 1], s->temp[2][i], 2);
        }
    }
}

static void decode_gray_bitstream(HYuvContext *s, int count)
{
    int i;

    count /= 2;

    if (count >= (get_bits_left(&s->gb)) / (31 * 2)) {
        for (i = 0; i < count && get_bits_left(&s->gb) > 0; i++) {
            READ_2PIX(s->temp[0][2 * i], s->temp[0][2 * i + 1], 0);
        }
    } else {
        for (i = 0; i < count; i++) {
            READ_2PIX(s->temp[0][2 * i], s->temp[0][2 * i + 1], 0);
        }
    }
}

static av_always_inline void decode_bgr_1(HYuvContext *s, int count,
                                          int decorrelate, int alpha)
{
    int i;
    for (i = 0; i < count; i++) {
        int code = get_vlc2(&s->gb, s->vlc[3].table, VLC_BITS, 1);
        if (code != -1) {
            *(uint32_t *) &s->temp[0][4 * i] = s->pix_bgr_map[code];
        } else if (decorrelate) {
            s->temp[0][4 * i + G] = get_vlc2(&s->gb, s->vlc[1].table, VLC_BITS, 3);
            s->temp[0][4 * i + B] = get_vlc2(&s->gb, s->vlc[0].table, VLC_BITS, 3) +
                                    s->temp[0][4 * i + G];
            s->temp[0][4 * i + R] = get_vlc2(&s->gb, s->vlc[2].table, VLC_BITS, 3) +
                                    s->temp[0][4 * i + G];
        } else {
            s->temp[0][4 * i + B] = get_vlc2(&s->gb, s->vlc[0].table, VLC_BITS, 3);
            s->temp[0][4 * i + G] = get_vlc2(&s->gb, s->vlc[1].table, VLC_BITS, 3);
            s->temp[0][4 * i + R] = get_vlc2(&s->gb, s->vlc[2].table, VLC_BITS, 3);
        }
        if (alpha)
            s->temp[0][4 * i + A] = get_vlc2(&s->gb, s->vlc[2].table, VLC_BITS, 3);
    }
}

static void decode_bgr_bitstream(HYuvContext *s, int count)
{
    if (s->decorrelate) {
        if (s->bitstream_bpp == 24)
            decode_bgr_1(s, count, 1, 0);
        else
            decode_bgr_1(s, count, 1, 1);
    } else {
        if (s->bitstream_bpp == 24)
            decode_bgr_1(s, count, 0, 0);
        else
            decode_bgr_1(s, count, 0, 1);
    }
}

static void draw_slice(HYuvContext *s, AVFrame *frame, int y)
{
    int h, cy, i;
    int offset[AV_NUM_DATA_POINTERS];

    if (s->avctx->draw_horiz_band == NULL)
        return;

    h  = y - s->last_slice_end;
    y -= h;

    if (s->bitstream_bpp == 12)
        cy = y >> 1;
    else
        cy = y;

    offset[0] = frame->linesize[0] * y;
    offset[1] = frame->linesize[1] * cy;
    offset[2] = frame->linesize[2] * cy;
    for (i = 3; i < AV_NUM_DATA_POINTERS; i++)
        offset[i] = 0;
    emms_c();

    s->avctx->draw_horiz_band(s->avctx, frame, offset, y, 3, h);

    s->last_slice_end = y + h;
}

static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
                        AVPacket *avpkt)
{
    const uint8_t *buf = avpkt->data;
    int buf_size       = avpkt->size;
    HYuvContext *s = avctx->priv_data;
    const int width  = s->width;
    const int width2 = s->width >> 1;
    const int height = s->height;
    int fake_ystride, fake_ustride, fake_vstride;
    ThreadFrame frame = { .f = data };
    AVFrame *const p = data;
    int table_size = 0, ret;

    av_fast_malloc(&s->bitstream_buffer,
                   &s->bitstream_buffer_size,
                   buf_size + FF_INPUT_BUFFER_PADDING_SIZE);
    if (!s->bitstream_buffer)
        return AVERROR(ENOMEM);

    memset(s->bitstream_buffer + buf_size, 0, FF_INPUT_BUFFER_PADDING_SIZE);
    s->bdsp.bswap_buf((uint32_t *) s->bitstream_buffer,
                      (const uint32_t *) buf, buf_size / 4);

    if ((ret = ff_thread_get_buffer(avctx, &frame, 0)) < 0) {
        av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
        return ret;
    }

    if (s->context) {
        table_size = read_huffman_tables(s, s->bitstream_buffer, buf_size);
        if (table_size < 0)
            return table_size;
    }

    if ((unsigned) (buf_size - table_size) >= INT_MAX / 8)
        return AVERROR_INVALIDDATA;

    if ((ret = init_get_bits(&s->gb, s->bitstream_buffer + table_size,
                             (buf_size - table_size) * 8)) < 0)
        return ret;

    fake_ystride = s->interlaced ? p->linesize[0] * 2 : p->linesize[0];
    fake_ustride = s->interlaced ? p->linesize[1] * 2 : p->linesize[1];
    fake_vstride = s->interlaced ? p->linesize[2] * 2 : p->linesize[2];

    s->last_slice_end = 0;

    if (s->bitstream_bpp < 24) {
        int y, cy;
        int lefty, leftu, leftv;
        int lefttopy, lefttopu, lefttopv;

        if (s->yuy2) {
            p->data[0][3] = get_bits(&s->gb, 8);
            p->data[0][2] = get_bits(&s->gb, 8);
            p->data[0][1] = get_bits(&s->gb, 8);
            p->data[0][0] = get_bits(&s->gb, 8);

            avpriv_report_missing_feature(avctx, "YUY2 output");
            return AVERROR_PATCHWELCOME;
        } else {
            leftv         =
            p->data[2][0] = get_bits(&s->gb, 8);
            lefty         =
            p->data[0][1] = get_bits(&s->gb, 8);
            leftu         =
            p->data[1][0] = get_bits(&s->gb, 8);
            p->data[0][0] = get_bits(&s->gb, 8);

            switch (s->predictor) {
            case LEFT:
            case PLANE:
                decode_422_bitstream(s, width - 2);
                lefty = s->hdsp.add_hfyu_left_pred(p->data[0] + 2, s->temp[0],
                                                   width - 2, lefty);
                if (!(s->flags & CODEC_FLAG_GRAY)) {
                    leftu = s->hdsp.add_hfyu_left_pred(p->data[1] + 1, s->temp[1], width2 - 1, leftu);
                    leftv = s->hdsp.add_hfyu_left_pred(p->data[2] + 1, s->temp[2], width2 - 1, leftv);
                }

                for (cy = y = 1; y < s->height; y++, cy++) {
                    uint8_t *ydst, *udst, *vdst;

                    if (s->bitstream_bpp == 12) {
                        decode_gray_bitstream(s, width);

                        ydst = p->data[0] + p->linesize[0] * y;

                        lefty = s->hdsp.add_hfyu_left_pred(ydst, s->temp[0],
                                                           width, lefty);
                        if (s->predictor == PLANE) {
                            if (y > s->interlaced)
                                s->hdsp.add_bytes(ydst, ydst - fake_ystride, width);
                        }
                        y++;
                        if (y >= s->height)
                            break;
                    }

                    draw_slice(s, p, y);

                    ydst = p->data[0] + p->linesize[0] * y;
                    udst = p->data[1] + p->linesize[1] * cy;
                    vdst = p->data[2] + p->linesize[2] * cy;

                    decode_422_bitstream(s, width);
                    lefty = s->hdsp.add_hfyu_left_pred(ydst, s->temp[0],
                                                       width, lefty);
                    if (!(s->flags & CODEC_FLAG_GRAY)) {
                        leftu = s->hdsp.add_hfyu_left_pred(udst, s->temp[1], width2, leftu);
                        leftv = s->hdsp.add_hfyu_left_pred(vdst, s->temp[2], width2, leftv);
                    }
                    if (s->predictor == PLANE) {
                        if (cy > s->interlaced) {
                            s->hdsp.add_bytes(ydst, ydst - fake_ystride, width);
                            if (!(s->flags & CODEC_FLAG_GRAY)) {
                                s->hdsp.add_bytes(udst, udst - fake_ustride, width2);
                                s->hdsp.add_bytes(vdst, vdst - fake_vstride, width2);
                            }
                        }
                    }
                }
                draw_slice(s, p, height);

                break;
            case MEDIAN:
                /* first line except first 2 pixels is left predicted */
                decode_422_bitstream(s, width - 2);
                lefty = s->hdsp.add_hfyu_left_pred(p->data[0] + 2, s->temp[0],
                                                   width - 2, lefty);
                if (!(s->flags & CODEC_FLAG_GRAY)) {
                    leftu = s->hdsp.add_hfyu_left_pred(p->data[1] + 1, s->temp[1], width2 - 1, leftu);
                    leftv = s->hdsp.add_hfyu_left_pred(p->data[2] + 1, s->temp[2], width2 - 1, leftv);
                }

                cy = y = 1;

                /* second line is left predicted for interlaced case */
                if (s->interlaced) {
                    decode_422_bitstream(s, width);
                    lefty = s->hdsp.add_hfyu_left_pred(p->data[0] + p->linesize[0],
                                                       s->temp[0], width, lefty);
                    if (!(s->flags & CODEC_FLAG_GRAY)) {
                        leftu = s->hdsp.add_hfyu_left_pred(p->data[1] + p->linesize[2], s->temp[1], width2, leftu);
                        leftv = s->hdsp.add_hfyu_left_pred(p->data[2] + p->linesize[1], s->temp[2], width2, leftv);
                    }
                    y++;
                    cy++;
                }

                /* next 4 pixels are left predicted too */
                decode_422_bitstream(s, 4);
                lefty = s->hdsp.add_hfyu_left_pred(p->data[0] + fake_ystride,
                                                   s->temp[0], 4, lefty);
                if (!(s->flags & CODEC_FLAG_GRAY)) {
                    leftu = s->hdsp.add_hfyu_left_pred(p->data[1] + fake_ustride, s->temp[1], 2, leftu);
                    leftv = s->hdsp.add_hfyu_left_pred(p->data[2] + fake_vstride, s->temp[2], 2, leftv);
                }

                /* next line except the first 4 pixels is median predicted */
                lefttopy = p->data[0][3];
                decode_422_bitstream(s, width - 4);
                s->hdsp.add_hfyu_median_pred(p->data[0] + fake_ystride + 4,
                                             p->data[0] + 4, s->temp[0],
                                             width - 4, &lefty, &lefttopy);
                if (!(s->flags & CODEC_FLAG_GRAY)) {
                    lefttopu = p->data[1][1];
                    lefttopv = p->data[2][1];
                    s->hdsp.add_hfyu_median_pred(p->data[1] + fake_ustride + 2, p->data[1] + 2, s->temp[1], width2 - 2, &leftu, &lefttopu);
                    s->hdsp.add_hfyu_median_pred(p->data[2] + fake_vstride + 2, p->data[2] + 2, s->temp[2], width2 - 2, &leftv, &lefttopv);
                }
                y++;
                cy++;

                for (; y < height; y++, cy++) {
                    uint8_t *ydst, *udst, *vdst;

                    if (s->bitstream_bpp == 12) {
                        while (2 * cy > y) {
                            decode_gray_bitstream(s, width);
                            ydst = p->data[0] + p->linesize[0] * y;
                            s->hdsp.add_hfyu_median_pred(ydst, ydst - fake_ystride,
                                                         s->temp[0], width,
                                                         &lefty, &lefttopy);
                            y++;
                        }
                        if (y >= height)
                            break;
                    }
                    draw_slice(s, p, y);

                    decode_422_bitstream(s, width);

                    ydst = p->data[0] + p->linesize[0] * y;
                    udst = p->data[1] + p->linesize[1] * cy;
                    vdst = p->data[2] + p->linesize[2] * cy;

                    s->hdsp.add_hfyu_median_pred(ydst, ydst - fake_ystride,
                                                 s->temp[0], width,
                                                 &lefty, &lefttopy);
                    if (!(s->flags & CODEC_FLAG_GRAY)) {
                        s->hdsp.add_hfyu_median_pred(udst, udst - fake_ustride, s->temp[1], width2, &leftu, &lefttopu);
                        s->hdsp.add_hfyu_median_pred(vdst, vdst - fake_vstride, s->temp[2], width2, &leftv, &lefttopv);
                    }
                }

                draw_slice(s, p, height);
                break;
            }
        }
    } else {
        int y;
        int leftr, leftg, leftb, lefta;
        const int last_line = (height - 1) * p->linesize[0];

        if (s->bitstream_bpp == 32) {
            lefta = p->data[0][last_line + A] = get_bits(&s->gb, 8);
            leftr = p->data[0][last_line + R] = get_bits(&s->gb, 8);
            leftg = p->data[0][last_line + G] = get_bits(&s->gb, 8);
            leftb = p->data[0][last_line + B] = get_bits(&s->gb, 8);
        } else {
            leftr = p->data[0][last_line + R] = get_bits(&s->gb, 8);
            leftg = p->data[0][last_line + G] = get_bits(&s->gb, 8);
            leftb = p->data[0][last_line + B] = get_bits(&s->gb, 8);
            lefta = p->data[0][last_line + A] = 255;
            skip_bits(&s->gb, 8);
        }

        if (s->bgr32) {
            switch (s->predictor) {
            case LEFT:
            case PLANE:
                decode_bgr_bitstream(s, width - 1);
                s->hdsp.add_hfyu_left_pred_bgr32(p->data[0] + last_line + 4,
                                                 s->temp[0], width - 1, &leftr,
                                                 &leftg, &leftb, &lefta);

                for (y = s->height - 2; y >= 0; y--) { // Yes it is stored upside down.
                    decode_bgr_bitstream(s, width);

                    s->hdsp.add_hfyu_left_pred_bgr32(p->data[0] + p->linesize[0] * y,
                                                     s->temp[0], width, &leftr,
                                                     &leftg, &leftb, &lefta);
                    if (s->predictor == PLANE) {
                        if (s->bitstream_bpp != 32)
                            lefta = 0;
                        if ((y & s->interlaced) == 0 &&
                            y < s->height - 1 - s->interlaced) {
                            s->hdsp.add_bytes(p->data[0] + p->linesize[0] * y,
                                              p->data[0] + p->linesize[0] * y +
                                              fake_ystride, fake_ystride);
                        }
                    }
                }
                // just 1 large slice as this is not possible in reverse order
                draw_slice(s, p, height);
                break;
            default:
                av_log(avctx, AV_LOG_ERROR,
                       "prediction type not supported!\n");
            }
        } else {
            avpriv_report_missing_feature(avctx, "BGR24 output");
            return AVERROR_PATCHWELCOME;
        }
    }
    emms_c();

    *got_frame = 1;

    return (get_bits_count(&s->gb) + 31) / 32 * 4 + table_size;
}

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

    ff_huffyuv_common_end(s);
    av_freep(&s->bitstream_buffer);

    for (i = 0; i < 6; i++)
        ff_free_vlc(&s->vlc[i]);

    return 0;
}

AVCodec ff_huffyuv_decoder = {
    .name             = "huffyuv",
    .long_name        = NULL_IF_CONFIG_SMALL("Huffyuv / HuffYUV"),
    .type             = AVMEDIA_TYPE_VIDEO,
    .id               = AV_CODEC_ID_HUFFYUV,
    .priv_data_size   = sizeof(HYuvContext),
    .init             = decode_init,
    .close            = decode_end,
    .decode           = decode_frame,
    .capabilities     = CODEC_CAP_DR1 | CODEC_CAP_DRAW_HORIZ_BAND |
                        CODEC_CAP_FRAME_THREADS,
    .init_thread_copy = ONLY_IF_THREADS_ENABLED(decode_init_thread_copy),
};

#if CONFIG_FFVHUFF_DECODER
AVCodec ff_ffvhuff_decoder = {
    .name             = "ffvhuff",
    .long_name        = NULL_IF_CONFIG_SMALL("Huffyuv FFmpeg variant"),
    .type             = AVMEDIA_TYPE_VIDEO,
    .id               = AV_CODEC_ID_FFVHUFF,
    .priv_data_size   = sizeof(HYuvContext),
    .init             = decode_init,
    .close            = decode_end,
    .decode           = decode_frame,
    .capabilities     = CODEC_CAP_DR1 | CODEC_CAP_DRAW_HORIZ_BAND |
                        CODEC_CAP_FRAME_THREADS,
    .init_thread_copy = ONLY_IF_THREADS_ENABLED(decode_init_thread_copy),
};
#endif /* CONFIG_FFVHUFF_DECODER */