/*
  * 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 "dsputil.h"

 #include "libavutil/imgutils.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 << 5) + (lo << 10);
     hi = ydt[p2];
     hi += (hi << 5) + (hi << 10);

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

 }
 

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

 {
     int r, b, lo;

     b = cdt[p2];
     r = cdt[p1] << 10;
     lo = b + r;

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

 }
 

 #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 << 16)) << 1;

 }
 
 static int make_ydt24_entry(int p1, int p2, int16_t *ydt)
 {
     int lo, hi;

     lo = ydt[p1];
     hi = ydt[p2];

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

 }
 
 static int make_cdt24_entry(int p1, int p2, int16_t *cdt)
 {
     int r, b;

     b = cdt[p2];
     r = cdt[p1]<<16;

     return (b+r) << 1;

 }
 

 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;

     int width_shift = 0;

     int new_pix_fmt;

     struct frame_header header;
     uint8_t header_buffer[128];  /* 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 -1;
     }
 
     /* unscramble the header bytes with a XOR operation */
     memset(header_buffer, 0, 128);
     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 -1;
         } 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) {

         av_log_ask_for_sample(s->avctx, "SPRITE frame found.\n");

         /* FIXME header.width, height, xoffset and yoffset aren't initialized */
 #if 0

         s->w = header.width;
         s->h = header.height;
         s->x = header.xoffset;
         s->y = header.yoffset;

 #else
         return -1;
 #endif

     } 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;

                 av_log_ask_for_sample(s->avctx, "INTERPOLATION selected.\n");

             }

         }
     }
 

     if (header.compression >= 17) {

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

         return -1;
     }

 
     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 -1;
         }
     }

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

         new_pix_fmt = PIX_FMT_RGB32;

         width_shift = 1;
     } else

         new_pix_fmt = PIX_FMT_RGB555; // RGB565 is supported as well
 

     s->w >>= width_shift;
     if (av_image_check_size(s->w, s->h, 0, s->avctx) < 0)
         return -1;
 

     if (s->w != s->avctx->width || s->h != s->avctx->height ||
         new_pix_fmt != s->avctx->pix_fmt) {
         if (s->frame.data[0])
             s->avctx->release_buffer(s->avctx, &s->frame);

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

         s->avctx->pix_fmt = new_pix_fmt;
         avcodec_set_dimensions(s->avctx, s->w, s->h);
         av_fast_malloc(&s->vert_pred, &s->vert_pred_size, s->avctx->width * sizeof(unsigned int));
     }

     /* 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 == 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;
     } 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 = PIX_FMT_RGB24;

 //    else

 //        avctx->pix_fmt = PIX_FMT_RGB555;

     avcodec_get_frame_defaults(&s->frame);

     s->frame.data[0] = NULL;

 
     /* 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));

 
     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 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 \
                 index++; \
         } \
     } else \
         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 \
                 index++; \
         } \
     } else \

         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 \
                 index++; \
         } \
     } else \
         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 \
                 index++; \
         } \
     } else \
         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;
         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,
                                     void *data, int *data_size,

                                     AVPacket *avpkt)

 {

     const uint8_t *buf = avpkt->data;
     int buf_size = avpkt->size;

     TrueMotion1Context *s = avctx->priv_data;

 
     s->buf = buf;
     s->size = buf_size;
 
     if (truemotion1_decode_header(s) == -1)
         return -1;
 

     s->frame.reference = 3;

     s->frame.buffer_hints = FF_BUFFER_HINTS_VALID |
         FF_BUFFER_HINTS_PRESERVE | FF_BUFFER_HINTS_REUSABLE;
     if (avctx->reget_buffer(avctx, &s->frame) < 0) {

         av_log(s->avctx, AV_LOG_ERROR, "get_buffer() failed\n");
         return -1;
     }
 

     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);
     }
 
     *data_size = sizeof(AVFrame);
     *(AVFrame*)data = s->frame;
 
     /* report that the buffer was completely consumed */
     return buf_size;
 }
 

 static av_cold int truemotion1_decode_end(AVCodecContext *avctx)

 {

     TrueMotion1Context *s = avctx->priv_data;

     if (s->frame.data[0])
         avctx->release_buffer(avctx, &s->frame);

 
     av_free(s->vert_pred);
 
     return 0;
 }
 

 AVCodec ff_truemotion1_decoder = {

     .name           = "truemotion1",
     .type           = AVMEDIA_TYPE_VIDEO,
     .id             = CODEC_ID_TRUEMOTION1,
     .priv_data_size = sizeof(TrueMotion1Context),
     .init           = truemotion1_decode_init,
     .close          = truemotion1_decode_end,
     .decode         = truemotion1_decode_frame,
     .capabilities   = CODEC_CAP_DR1,

     .long_name = NULL_IF_CONFIG_SMALL("Duck TrueMotion 1.0"),

 };