/*

 * Duck TrueMotion 1.0 Decoder

 * Copyright (C) 2003 Alex Beregszaszi & Mike Melanson

 *

 * 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

 * Duck TrueMotion v1 Video Decoder by

 * Alex Beregszaszi and

 * Mike Melanson (melanson@pcisys.net)

 *

 * The TrueMotion v1 decoder presently only decodes 16-bit TM1 data and

 * outputs RGB555 (or RGB565) data. 24-bit TM1 data is not supported yet.

 */

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include "avcodec.h"

#include "codec_internal.h"

#include "decode.h"

#include "libavutil/imgutils.h"

#include "libavutil/internal.h"

#include "libavutil/intreadwrite.h"

#include "libavutil/mem.h"

#include "truemotion1data.h"

typedef struct TrueMotion1Context {

    AVCodecContext *avctx;

    AVFrame *frame;

    const uint8_t *buf;

    int size;

    const uint8_t *mb_change_bits;

    int mb_change_bits_row_size;

    const uint8_t *index_stream;

    int index_stream_size;

    int flags;

    int x, y, w, h;

    uint32_t y_predictor_table[1024];

    uint32_t c_predictor_table[1024];

    uint32_t fat_y_predictor_table[1024];

    uint32_t fat_c_predictor_table[1024];

    int compression;

    int block_type;

    int block_width;

    int block_height;

    int16_t ydt[8];

    int16_t cdt[8];

    int16_t fat_ydt[8];

    int16_t fat_cdt[8];

    int last_deltaset, last_vectable;

    unsigned int *vert_pred;

    int vert_pred_size;

} TrueMotion1Context;

#define FLAG_SPRITE         32

#define FLAG_KEYFRAME       16

#define FLAG_INTERFRAME      8

#define FLAG_INTERPOLATED    4

struct frame_header {

    uint8_t header_size;

    uint8_t compression;

    uint8_t deltaset;

    uint8_t vectable;

    uint16_t ysize;

    uint16_t xsize;

    uint16_t checksum;

    uint8_t version;

    uint8_t header_type;

    uint8_t flags;

    uint8_t control;

    uint16_t xoffset;

    uint16_t yoffset;

    uint16_t width;

    uint16_t height;

};

#define ALGO_NOP        0

#define ALGO_RGB16V     1

#define ALGO_RGB16H     2

#define ALGO_RGB24H     3

/* these are the various block sizes that can occupy a 4x4 block */

#define BLOCK_2x2  0

#define BLOCK_2x4  1

#define BLOCK_4x2  2

#define BLOCK_4x4  3

typedef struct comp_types {

    int algorithm;

    int block_width; // vres

    int block_height; // hres

    int block_type;

} comp_types;

/* { valid for metatype }, algorithm, num of deltas, vert res, horiz res */

static const comp_types compression_types[17] = {

    { ALGO_NOP,    0, 0, 0 },

    { ALGO_RGB16V, 4, 4, BLOCK_4x4 },

    { ALGO_RGB16H, 4, 4, BLOCK_4x4 },

    { ALGO_RGB16V, 4, 2, BLOCK_4x2 },

    { ALGO_RGB16H, 4, 2, BLOCK_4x2 },

    { ALGO_RGB16V, 2, 4, BLOCK_2x4 },

    { ALGO_RGB16H, 2, 4, BLOCK_2x4 },

    { ALGO_RGB16V, 2, 2, BLOCK_2x2 },

    { ALGO_RGB16H, 2, 2, BLOCK_2x2 },

    { ALGO_NOP,    4, 4, BLOCK_4x4 },

    { ALGO_RGB24H, 4, 4, BLOCK_4x4 },

    { ALGO_NOP,    4, 2, BLOCK_4x2 },

    { ALGO_RGB24H, 4, 2, BLOCK_4x2 },

    { ALGO_NOP,    2, 4, BLOCK_2x4 },

    { ALGO_RGB24H, 2, 4, BLOCK_2x4 },

    { ALGO_NOP,    2, 2, BLOCK_2x2 },

    { ALGO_RGB24H, 2, 2, BLOCK_2x2 }

};

static void select_delta_tables(TrueMotion1Context *s, int delta_table_index)

{

    int i;

    if (delta_table_index > 3)

        return;

    memcpy(s->ydt, ydts[delta_table_index], 8 * sizeof(int16_t));

    memcpy(s->cdt, cdts[delta_table_index], 8 * sizeof(int16_t));

    memcpy(s->fat_ydt, fat_ydts[delta_table_index], 8 * sizeof(int16_t));

    memcpy(s->fat_cdt, fat_cdts[delta_table_index], 8 * sizeof(int16_t));

    /* Y skinny deltas need to be halved for some reason; maybe the

     * skinny Y deltas should be modified */

    for (i = 0; i < 8; i++)

    {

        /* drop the lsb before dividing by 2-- net effect: round down

         * when dividing a negative number (e.g., -3/2 = -2, not -1) */

        s->ydt[i] &= 0xFFFE;

        s->ydt[i] /= 2;

    }

}

#if HAVE_BIGENDIAN

static int make_ydt15_entry(int p2, int p1, int16_t *ydt)

#else

static int make_ydt15_entry(int p1, int p2, int16_t *ydt)

#endif

{

    int lo, hi;

    lo = ydt[p1];

    lo += (lo * 32) + (lo * 1024);

    hi = ydt[p2];

    hi += (hi * 32) + (hi * 1024);

    return (lo + (hi * (1U << 16))) * 2;

}

static int make_cdt15_entry(int p1, int p2, int16_t *cdt)

{

    int r, b, lo;

    b = cdt[p2];

    r = cdt[p1] * 1024;

    lo = b + r;

    return (lo + (lo * (1U << 16))) * 2;

}

#if HAVE_BIGENDIAN

static int make_ydt16_entry(int p2, int p1, int16_t *ydt)

#else

static int make_ydt16_entry(int p1, int p2, int16_t *ydt)

#endif

{

    int lo, hi;

    lo = ydt[p1];

    lo += (lo << 6) + (lo << 11);

    hi = ydt[p2];

    hi += (hi << 6) + (hi << 11);

    return (lo + (hi << 16)) << 1;

}

static int make_cdt16_entry(int p1, int p2, int16_t *cdt)

{

    int r, b, lo;

    b = cdt[p2];

    r = cdt[p1] << 11;

    lo = b + r;

    return (lo + (lo * (1 << 16))) * 2;

}

static int make_ydt24_entry(int p1, int p2, int16_t *ydt)

{

    int lo, hi;

    lo = ydt[p1];

    hi = ydt[p2];

    return (lo + (hi * (1 << 8)) + (hi * (1 << 16))) * 2;

}

static int make_cdt24_entry(int p1, int p2, int16_t *cdt)

{

    int r, b;

    b = cdt[p2];

    r = cdt[p1] * (1 << 16);

    return (b+r) * 2;

}

static void gen_vector_table15(TrueMotion1Context *s, const uint8_t *sel_vector_table)

{

    int len, i, j;

    unsigned char delta_pair;

    for (i = 0; i < 1024; i += 4)

    {

        len = *sel_vector_table++ / 2;

        for (j = 0; j < len; j++)

        {

            delta_pair = *sel_vector_table++;

            s->y_predictor_table[i+j] = 0xfffffffe &

                make_ydt15_entry(delta_pair >> 4, delta_pair & 0xf, s->ydt);

            s->c_predictor_table[i+j] = 0xfffffffe &

                make_cdt15_entry(delta_pair >> 4, delta_pair & 0xf, s->cdt);

        }

        s->y_predictor_table[i+(j-1)] |= 1;

        s->c_predictor_table[i+(j-1)] |= 1;

    }

}

static void gen_vector_table16(TrueMotion1Context *s, const uint8_t *sel_vector_table)

{

    int len, i, j;

    unsigned char delta_pair;

    for (i = 0; i < 1024; i += 4)

    {

        len = *sel_vector_table++ / 2;

        for (j = 0; j < len; j++)

        {

            delta_pair = *sel_vector_table++;

            s->y_predictor_table[i+j] = 0xfffffffe &

                make_ydt16_entry(delta_pair >> 4, delta_pair & 0xf, s->ydt);

            s->c_predictor_table[i+j] = 0xfffffffe &

                make_cdt16_entry(delta_pair >> 4, delta_pair & 0xf, s->cdt);

        }

        s->y_predictor_table[i+(j-1)] |= 1;

        s->c_predictor_table[i+(j-1)] |= 1;

    }

}

static void gen_vector_table24(TrueMotion1Context *s, const uint8_t *sel_vector_table)

{

    int len, i, j;

    unsigned char delta_pair;

    for (i = 0; i < 1024; i += 4)

    {

        len = *sel_vector_table++ / 2;

        for (j = 0; j < len; j++)

        {

            delta_pair = *sel_vector_table++;

            s->y_predictor_table[i+j] = 0xfffffffe &

                make_ydt24_entry(delta_pair >> 4, delta_pair & 0xf, s->ydt);

            s->c_predictor_table[i+j] = 0xfffffffe &

                make_cdt24_entry(delta_pair >> 4, delta_pair & 0xf, s->cdt);

            s->fat_y_predictor_table[i+j] = 0xfffffffe &

                make_ydt24_entry(delta_pair >> 4, delta_pair & 0xf, s->fat_ydt);

            s->fat_c_predictor_table[i+j] = 0xfffffffe &

                make_cdt24_entry(delta_pair >> 4, delta_pair & 0xf, s->fat_cdt);

        }

        s->y_predictor_table[i+(j-1)] |= 1;

        s->c_predictor_table[i+(j-1)] |= 1;

        s->fat_y_predictor_table[i+(j-1)] |= 1;

        s->fat_c_predictor_table[i+(j-1)] |= 1;

    }

}

/* Returns the number of bytes consumed from the bytestream. Returns -1 if

 * there was an error while decoding the header */

static int truemotion1_decode_header(TrueMotion1Context *s)

{

    int i, ret;

    int width_shift = 0;

    int new_pix_fmt;

    struct frame_header header;

    uint8_t header_buffer[128] = { 0 };  /* logical maximum size of the header */

    const uint8_t *sel_vector_table;

    header.header_size = ((s->buf[0] >> 5) | (s->buf[0] << 3)) & 0x7f;

    if (s->buf[0] < 0x10)

    {

        av_log(s->avctx, AV_LOG_ERROR, "invalid header size (%d)\n", s->buf[0]);

        return AVERROR_INVALIDDATA;

    }

    if (header.header_size + 1 > s->size) {

        av_log(s->avctx, AV_LOG_ERROR, "Input packet too small.\n");

        return AVERROR_INVALIDDATA;

    }

    /* unscramble the header bytes with a XOR operation */

    for (i = 1; i < header.header_size; i++)

        header_buffer[i - 1] = s->buf[i] ^ s->buf[i + 1];

    header.compression = header_buffer[0];

    header.deltaset = header_buffer[1];

    header.vectable = header_buffer[2];

    header.ysize = AV_RL16(&header_buffer[3]);

    header.xsize = AV_RL16(&header_buffer[5]);

    header.checksum = AV_RL16(&header_buffer[7]);

    header.version = header_buffer[9];

    header.header_type = header_buffer[10];

    header.flags = header_buffer[11];

    header.control = header_buffer[12];

    /* Version 2 */

    if (header.version >= 2)

    {

        if (header.header_type > 3)

        {

            av_log(s->avctx, AV_LOG_ERROR, "invalid header type (%d)\n", header.header_type);

            return AVERROR_INVALIDDATA;

        } else if ((header.header_type == 2) || (header.header_type == 3)) {

            s->flags = header.flags;

            if (!(s->flags & FLAG_INTERFRAME))

                s->flags |= FLAG_KEYFRAME;

        } else

            s->flags = FLAG_KEYFRAME;

    } else /* Version 1 */

        s->flags = FLAG_KEYFRAME;

    if (s->flags & FLAG_SPRITE) {

        avpriv_request_sample(s->avctx, "Frame with sprite");

        /* FIXME header.width, height, xoffset and yoffset aren't initialized */

        return AVERROR_PATCHWELCOME;

    } else {

        s->w = header.xsize;

        s->h = header.ysize;

        if (header.header_type < 2) {

            if ((s->w < 213) && (s->h >= 176))

            {

                s->flags |= FLAG_INTERPOLATED;

                avpriv_request_sample(s->avctx, "Interpolated frame");

            }

        }

    }

    if (header.compression >= 17) {

        av_log(s->avctx, AV_LOG_ERROR, "invalid compression type (%d)\n", header.compression);

        return AVERROR_INVALIDDATA;

    }

    if ((header.deltaset != s->last_deltaset) ||

        (header.vectable != s->last_vectable))

        select_delta_tables(s, header.deltaset);

    if ((header.compression & 1) && header.header_type)

        sel_vector_table = pc_tbl2;

    else {

        if (header.vectable > 0 && header.vectable < 4)

            sel_vector_table = tables[header.vectable - 1];

        else {

            av_log(s->avctx, AV_LOG_ERROR, "invalid vector table id (%d)\n", header.vectable);

            return AVERROR_INVALIDDATA;

        }

    }

    if (compression_types[header.compression].algorithm == ALGO_RGB24H) {

        new_pix_fmt = AV_PIX_FMT_0RGB32;

        width_shift = 1;

    } else

        new_pix_fmt = AV_PIX_FMT_RGB555; // RGB565 is supported as well

    s->w >>= width_shift;

    if (s->w & 1) {

        avpriv_request_sample(s->avctx, "Frame with odd width");

        return AVERROR_PATCHWELCOME;

    }

    if (s->h & 3) {

        avpriv_request_sample(s->avctx, "Frame with height not being a multiple of 4");

        return AVERROR_PATCHWELCOME;

    }

    if (s->w != s->avctx->width || s->h != s->avctx->height ||

        new_pix_fmt != s->avctx->pix_fmt) {

        av_frame_unref(s->frame);

        s->avctx->sample_aspect_ratio = (AVRational){ 1 << width_shift, 1 };

        s->avctx->pix_fmt = new_pix_fmt;

        if ((ret = ff_set_dimensions(s->avctx, s->w, s->h)) < 0)

            return ret;

        ff_set_sar(s->avctx, s->avctx->sample_aspect_ratio);

        av_fast_malloc(&s->vert_pred, &s->vert_pred_size, s->avctx->width * sizeof(unsigned int));

        if (!s->vert_pred)

            return AVERROR(ENOMEM);

    }

    /* There is 1 change bit per 4 pixels, so each change byte represents

     * 32 pixels; divide width by 4 to obtain the number of change bits and

     * then round up to the nearest byte. */

    s->mb_change_bits_row_size = ((s->avctx->width >> (2 - width_shift)) + 7) >> 3;

    if ((header.deltaset != s->last_deltaset) || (header.vectable != s->last_vectable))

    {

        if (compression_types[header.compression].algorithm == ALGO_RGB24H)

            gen_vector_table24(s, sel_vector_table);

        else

        if (s->avctx->pix_fmt == AV_PIX_FMT_RGB555)

            gen_vector_table15(s, sel_vector_table);

        else

            gen_vector_table16(s, sel_vector_table);

    }

    /* set up pointers to the other key data chunks */

    s->mb_change_bits = s->buf + header.header_size;

    if (s->flags & FLAG_KEYFRAME) {

        /* no change bits specified for a keyframe; only index bytes */

        s->index_stream = s->mb_change_bits;

        if (s->avctx->width * s->avctx->height / 2048 + header.header_size > s->size)

            return AVERROR_INVALIDDATA;

    } else {

        /* one change bit per 4x4 block */

        s->index_stream = s->mb_change_bits +

            (s->mb_change_bits_row_size * (s->avctx->height >> 2));

    }

    s->index_stream_size = s->size - (s->index_stream - s->buf);

    s->last_deltaset = header.deltaset;

    s->last_vectable = header.vectable;

    s->compression = header.compression;

    s->block_width = compression_types[header.compression].block_width;

    s->block_height = compression_types[header.compression].block_height;

    s->block_type = compression_types[header.compression].block_type;

    if (s->avctx->debug & FF_DEBUG_PICT_INFO)

        av_log(s->avctx, AV_LOG_INFO, "tables: %d / %d c:%d %dx%d t:%d %s%s%s%s\n",

            s->last_deltaset, s->last_vectable, s->compression, s->block_width,

            s->block_height, s->block_type,

            s->flags & FLAG_KEYFRAME ? " KEY" : "",

            s->flags & FLAG_INTERFRAME ? " INTER" : "",

            s->flags & FLAG_SPRITE ? " SPRITE" : "",

            s->flags & FLAG_INTERPOLATED ? " INTERPOL" : "");

    return header.header_size;

}

static av_cold int truemotion1_decode_init(AVCodecContext *avctx)

{

    TrueMotion1Context *s = avctx->priv_data;

    s->avctx = avctx;

    // FIXME: it may change ?

//    if (avctx->bits_per_sample == 24)

//        avctx->pix_fmt = AV_PIX_FMT_RGB24;

//    else

//        avctx->pix_fmt = AV_PIX_FMT_RGB555;

    s->frame = av_frame_alloc();

    if (!s->frame)

        return AVERROR(ENOMEM);

    /* there is a vertical predictor for each pixel in a line; each vertical

     * predictor is 0 to start with */

    av_fast_malloc(&s->vert_pred, &s->vert_pred_size, s->avctx->width * sizeof(unsigned int));

    if (!s->vert_pred)

        return AVERROR(ENOMEM);

    return 0;

}

/*

Block decoding order:

dxi: Y-Y

dxic: Y-C-Y

dxic2: Y-C-Y-C

hres,vres,i,i%vres (0 < i < 4)

2x2 0: 0 dxic2

2x2 1: 1 dxi

2x2 2: 0 dxic2

2x2 3: 1 dxi

2x4 0: 0 dxic2

2x4 1: 1 dxi

2x4 2: 2 dxi

2x4 3: 3 dxi

4x2 0: 0 dxic

4x2 1: 1 dxi

4x2 2: 0 dxic

4x2 3: 1 dxi

4x4 0: 0 dxic

4x4 1: 1 dxi

4x4 2: 2 dxi

4x4 3: 3 dxi

*/

#define GET_NEXT_INDEX() \

{\

    if (index_stream_index >= s->index_stream_size) { \

        av_log(s->avctx, AV_LOG_INFO, " help! truemotion1 decoder went out of bounds\n"); \

        return; \

    } \

    index = s->index_stream[index_stream_index++] * 4; \

}

#define INC_INDEX                                                   \

do {                                                                \

    if (index >= 1023) {                                            \

        av_log(s->avctx, AV_LOG_ERROR, "Invalid index value.\n");   \

        return;                                                     \

    }                                                               \

    index++;                                                        \

} while (0)

#define APPLY_C_PREDICTOR() \

    predictor_pair = s->c_predictor_table[index]; \

    horiz_pred += (predictor_pair >> 1); \

    if (predictor_pair & 1) { \

        GET_NEXT_INDEX() \

        if (!index) { \

            GET_NEXT_INDEX() \

            predictor_pair = s->c_predictor_table[index]; \

            horiz_pred += ((predictor_pair >> 1) * 5); \

            if (predictor_pair & 1) \

                GET_NEXT_INDEX() \

            else \

                INC_INDEX; \

        } \

    } else \

        INC_INDEX;

#define APPLY_C_PREDICTOR_24() \

    predictor_pair = s->c_predictor_table[index]; \

    horiz_pred += (predictor_pair >> 1); \

    if (predictor_pair & 1) { \

        GET_NEXT_INDEX() \

        if (!index) { \

            GET_NEXT_INDEX() \

            predictor_pair = s->fat_c_predictor_table[index]; \

            horiz_pred += (predictor_pair >> 1); \

            if (predictor_pair & 1) \

                GET_NEXT_INDEX() \

            else \

                INC_INDEX; \

        } \

    } else \

        INC_INDEX;

#define APPLY_Y_PREDICTOR() \

    predictor_pair = s->y_predictor_table[index]; \

    horiz_pred += (predictor_pair >> 1); \

    if (predictor_pair & 1) { \

        GET_NEXT_INDEX() \

        if (!index) { \

            GET_NEXT_INDEX() \

            predictor_pair = s->y_predictor_table[index]; \

            horiz_pred += ((predictor_pair >> 1) * 5); \

            if (predictor_pair & 1) \

                GET_NEXT_INDEX() \

            else \

                INC_INDEX; \

        } \

    } else \

        INC_INDEX;

#define APPLY_Y_PREDICTOR_24() \

    predictor_pair = s->y_predictor_table[index]; \

    horiz_pred += (predictor_pair >> 1); \

    if (predictor_pair & 1) { \

        GET_NEXT_INDEX() \

        if (!index) { \

            GET_NEXT_INDEX() \

            predictor_pair = s->fat_y_predictor_table[index]; \

            horiz_pred += (predictor_pair >> 1); \

            if (predictor_pair & 1) \

                GET_NEXT_INDEX() \

            else \

                INC_INDEX; \

        } \

    } else \

        INC_INDEX;

#define OUTPUT_PIXEL_PAIR() \

    *current_pixel_pair = *vert_pred + horiz_pred; \

    *vert_pred++ = *current_pixel_pair++;

static void truemotion1_decode_16bit(TrueMotion1Context *s)

{

    int y;

    int pixels_left;  /* remaining pixels on this line */

    unsigned int predictor_pair;

    unsigned int horiz_pred;

    unsigned int *vert_pred;

    unsigned int *current_pixel_pair;

    unsigned char *current_line = s->frame->data[0];

    int keyframe = s->flags & FLAG_KEYFRAME;

    /* these variables are for managing the stream of macroblock change bits */

    const unsigned char *mb_change_bits = s->mb_change_bits;

    unsigned char mb_change_byte;

    unsigned char mb_change_byte_mask;

    int mb_change_index;

    /* these variables are for managing the main index stream */

    int index_stream_index = 0;  /* yes, the index into the index stream */

    int index;

    /* clean out the line buffer */

    memset(s->vert_pred, 0, s->avctx->width * sizeof(unsigned int));

    GET_NEXT_INDEX();

    for (y = 0; y < s->avctx->height; y++) {

        /* re-init variables for the next line iteration */

        horiz_pred = 0;

        current_pixel_pair = (unsigned int *)current_line;

        vert_pred = s->vert_pred;

        mb_change_index = 0;

        if (!keyframe)

            mb_change_byte = mb_change_bits[mb_change_index++];

        mb_change_byte_mask = 0x01;

        pixels_left = s->avctx->width;

        while (pixels_left > 0) {

            if (keyframe || ((mb_change_byte & mb_change_byte_mask) == 0)) {

                switch (y & 3) {

                case 0:

                    /* if macroblock width is 2, apply C-Y-C-Y; else

                     * apply C-Y-Y */

                    if (s->block_width == 2) {

                        APPLY_C_PREDICTOR();

                        APPLY_Y_PREDICTOR();

                        OUTPUT_PIXEL_PAIR();

                        APPLY_C_PREDICTOR();

                        APPLY_Y_PREDICTOR();

                        OUTPUT_PIXEL_PAIR();

                    } else {

                        APPLY_C_PREDICTOR();

                        APPLY_Y_PREDICTOR();

                        OUTPUT_PIXEL_PAIR();

                        APPLY_Y_PREDICTOR();

                        OUTPUT_PIXEL_PAIR();

                    }

                    break;

                case 1:

                case 3:

                    /* always apply 2 Y predictors on these iterations */

                    APPLY_Y_PREDICTOR();

                    OUTPUT_PIXEL_PAIR();

                    APPLY_Y_PREDICTOR();

                    OUTPUT_PIXEL_PAIR();

                    break;

                case 2:

                    /* this iteration might be C-Y-C-Y, Y-Y, or C-Y-Y

                     * depending on the macroblock type */

                    if (s->block_type == BLOCK_2x2) {

                        APPLY_C_PREDICTOR();

                        APPLY_Y_PREDICTOR();

                        OUTPUT_PIXEL_PAIR();

                        APPLY_C_PREDICTOR();

                        APPLY_Y_PREDICTOR();

                        OUTPUT_PIXEL_PAIR();

                    } else if (s->block_type == BLOCK_4x2) {

                        APPLY_C_PREDICTOR();

                        APPLY_Y_PREDICTOR();

                        OUTPUT_PIXEL_PAIR();

                        APPLY_Y_PREDICTOR();

                        OUTPUT_PIXEL_PAIR();

                    } else {

                        APPLY_Y_PREDICTOR();

                        OUTPUT_PIXEL_PAIR();

                        APPLY_Y_PREDICTOR();

                        OUTPUT_PIXEL_PAIR();

                    }

                    break;

                }

            } else {

                /* skip (copy) four pixels, but reassign the horizontal

                 * predictor */

                *vert_pred++ = *current_pixel_pair++;

                horiz_pred = *current_pixel_pair - *vert_pred;

                *vert_pred++ = *current_pixel_pair++;

            }

            if (!keyframe) {

                mb_change_byte_mask <<= 1;

                /* next byte */

                if (!mb_change_byte_mask) {

                    mb_change_byte = mb_change_bits[mb_change_index++];

                    mb_change_byte_mask = 0x01;

                }

            }

            pixels_left -= 4;

        }

        /* next change row */

        if (((y + 1) & 3) == 0)

            mb_change_bits += s->mb_change_bits_row_size;

        current_line += s->frame->linesize[0];

    }

}

static void truemotion1_decode_24bit(TrueMotion1Context *s)

{

    int y;

    int pixels_left;  /* remaining pixels on this line */

    unsigned int predictor_pair;

    unsigned int horiz_pred;

    unsigned int *vert_pred;

    unsigned int *current_pixel_pair;

    unsigned char *current_line = s->frame->data[0];

    int keyframe = s->flags & FLAG_KEYFRAME;

    /* these variables are for managing the stream of macroblock change bits */

    const unsigned char *mb_change_bits = s->mb_change_bits;

    unsigned char mb_change_byte;

    unsigned char mb_change_byte_mask;

    int mb_change_index;

    /* these variables are for managing the main index stream */

    int index_stream_index = 0;  /* yes, the index into the index stream */

    int index;

    /* clean out the line buffer */

    memset(s->vert_pred, 0, s->avctx->width * sizeof(unsigned int));

    GET_NEXT_INDEX();

    for (y = 0; y < s->avctx->height; y++) {

        /* re-init variables for the next line iteration */

        horiz_pred = 0;

        current_pixel_pair = (unsigned int *)current_line;

        vert_pred = s->vert_pred;

        mb_change_index = 0;

        mb_change_byte = mb_change_bits[mb_change_index++];

        mb_change_byte_mask = 0x01;

        pixels_left = s->avctx->width;

        while (pixels_left > 0) {

            if (keyframe || ((mb_change_byte & mb_change_byte_mask) == 0)) {

                switch (y & 3) {

                case 0:

                    /* if macroblock width is 2, apply C-Y-C-Y; else

                     * apply C-Y-Y */

                    if (s->block_width == 2) {

                        APPLY_C_PREDICTOR_24();

                        APPLY_Y_PREDICTOR_24();

                        OUTPUT_PIXEL_PAIR();

                        APPLY_C_PREDICTOR_24();

                        APPLY_Y_PREDICTOR_24();

                        OUTPUT_PIXEL_PAIR();

                    } else {

                        APPLY_C_PREDICTOR_24();

                        APPLY_Y_PREDICTOR_24();

                        OUTPUT_PIXEL_PAIR();

                        APPLY_Y_PREDICTOR_24();

                        OUTPUT_PIXEL_PAIR();

                    }

                    break;

                case 1:

                case 3:

                    /* always apply 2 Y predictors on these iterations */

                    APPLY_Y_PREDICTOR_24();

                    OUTPUT_PIXEL_PAIR();

                    APPLY_Y_PREDICTOR_24();

                    OUTPUT_PIXEL_PAIR();

                    break;

                case 2:

                    /* this iteration might be C-Y-C-Y, Y-Y, or C-Y-Y

                     * depending on the macroblock type */

                    if (s->block_type == BLOCK_2x2) {

                        APPLY_C_PREDICTOR_24();

                        APPLY_Y_PREDICTOR_24();

                        OUTPUT_PIXEL_PAIR();

                        APPLY_C_PREDICTOR_24();

                        APPLY_Y_PREDICTOR_24();

                        OUTPUT_PIXEL_PAIR();

                    } else if (s->block_type == BLOCK_4x2) {

                        APPLY_C_PREDICTOR_24();

                        APPLY_Y_PREDICTOR_24();

                        OUTPUT_PIXEL_PAIR();

                        APPLY_Y_PREDICTOR_24();

                        OUTPUT_PIXEL_PAIR();

                    } else {

                        APPLY_Y_PREDICTOR_24();

                        OUTPUT_PIXEL_PAIR();

                        APPLY_Y_PREDICTOR_24();

                        OUTPUT_PIXEL_PAIR();

                    }

                    break;

                }

            } else {

                /* skip (copy) four pixels, but reassign the horizontal

                 * predictor */

                *vert_pred++ = *current_pixel_pair++;

                horiz_pred = *current_pixel_pair - *vert_pred;

                *vert_pred++ = *current_pixel_pair++;

            }

            if (!keyframe) {

                mb_change_byte_mask <<= 1;

                /* next byte */

                if (!mb_change_byte_mask) {

                    mb_change_byte = mb_change_bits[mb_change_index++];

                    mb_change_byte_mask = 0x01;

                }

            }

            pixels_left -= 2;

        }

        /* next change row */

        if (((y + 1) & 3) == 0)

            mb_change_bits += s->mb_change_bits_row_size;

        current_line += s->frame->linesize[0];

    }

}

static int truemotion1_decode_frame(AVCodecContext *avctx, AVFrame *rframe,

                                    int *got_frame, AVPacket *avpkt)

{

    const uint8_t *buf = avpkt->data;

    int ret, buf_size = avpkt->size;

    TrueMotion1Context *s = avctx->priv_data;

    s->buf = buf;

    s->size = buf_size;

    if ((ret = truemotion1_decode_header(s)) < 0)

        return ret;

    if ((ret = ff_reget_buffer(avctx, s->frame, 0)) < 0)

        return ret;

    if (compression_types[s->compression].algorithm == ALGO_RGB24H) {

        truemotion1_decode_24bit(s);

    } else if (compression_types[s->compression].algorithm != ALGO_NOP) {

        truemotion1_decode_16bit(s);

    }

    if ((ret = av_frame_ref(rframe, s->frame)) < 0)

        return ret;

    *got_frame      = 1;

    /* report that the buffer was completely consumed */

    return buf_size;

}

static av_cold int truemotion1_decode_end(AVCodecContext *avctx)

{

    TrueMotion1Context *s = avctx->priv_data;

    av_frame_free(&s->frame);

    av_freep(&s->vert_pred);

    return 0;

}

const FFCodec ff_truemotion1_decoder = {

    .p.name         = "truemotion1",

    CODEC_LONG_NAME("Duck TrueMotion 1.0"),

    .p.type         = AVMEDIA_TYPE_VIDEO,

    .p.id           = AV_CODEC_ID_TRUEMOTION1,

    .priv_data_size = sizeof(TrueMotion1Context),

    .init           = truemotion1_decode_init,

    .close          = truemotion1_decode_end,

    FF_CODEC_DECODE_CB(truemotion1_decode_frame),

    .p.capabilities = AV_CODEC_CAP_DR1,

    .caps_internal  = FF_CODEC_CAP_INIT_CLEANUP,

};