libavcodec/xan.c

   1 /*
   2  * Wing Commander/Xan Video Decoder
   3  * Copyright (C) 2003 the ffmpeg project
   4  *
   5  * This file is part of FFmpeg.
   6  *
   7  * FFmpeg is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * FFmpeg is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with FFmpeg; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 /**
  23  * @file xan.c
  24  * Xan video decoder for Wing Commander III computer game
  25  * by Mario Brito (mbrito@student.dei.uc.pt)
  26  * and Mike Melanson (melanson@pcisys.net)
  27  *
  28  * The xan_wc3 decoder outputs PAL8 data.
  29  */
  30
  31 #include <stdio.h>
  32 #include <stdlib.h>
  33 #include <string.h>
  34 #include <unistd.h>
  35
  36 #include "avcodec.h"
  37
  38 typedef struct XanContext {
  39
  40     AVCodecContext *avctx;
  41     AVFrame last_frame;
  42     AVFrame current_frame;
  43
  44     const unsigned char *buf;
  45     int size;
  46
  47     /* scratch space */
  48     unsigned char *buffer1;
  49     int buffer1_size;
  50     unsigned char *buffer2;
  51     int buffer2_size;
  52
  53     int frame_size;
  54
  55 } XanContext;
  56
  57 static av_cold int xan_decode_init(AVCodecContext *avctx)
  58 {
  59     XanContext *s = avctx->priv_data;
  60
  61     s->avctx = avctx;
  62     s->frame_size = 0;
  63
  64     if ((avctx->codec->id == CODEC_ID_XAN_WC3) &&
  65         (s->avctx->palctrl == NULL)) {
  66         av_log(avctx, AV_LOG_ERROR, " WC3 Xan video: palette expected.\n");
  67         return -1;
  68     }
  69
  70     avctx->pix_fmt = PIX_FMT_PAL8;
  71
  72     if(avcodec_check_dimensions(avctx, avctx->width, avctx->height))
  73         return -1;
  74
  75     s->buffer1_size = avctx->width * avctx->height;
  76     s->buffer1 = av_malloc(s->buffer1_size);
  77     s->buffer2_size = avctx->width * avctx->height;
  78     s->buffer2 = av_malloc(s->buffer2_size);
  79     if (!s->buffer1 || !s->buffer2)
  80         return -1;
  81
  82     return 0;
  83 }
  84
  85 /* This function is used in lieu of memcpy(). This decoder cannot use
  86  * memcpy because the memory locations often overlap and
  87  * memcpy doesn't like that; it's not uncommon, for example, for
  88  * dest = src+1, to turn byte A into  pattern AAAAAAAA.
  89  * This was originally repz movsb in Intel x86 ASM. */
  90 static inline void bytecopy(unsigned char *dest, const unsigned char *src, int count)
  91 {
  92     int i;
  93
  94     for (i = 0; i < count; i++)
  95         dest[i] = src[i];
  96 }
  97
  98 static int xan_huffman_decode(unsigned char *dest, const unsigned char *src,
  99     int dest_len)
 100 {
 101     unsigned char byte = *src++;
 102     unsigned char ival = byte + 0x16;
 103     const unsigned char * ptr = src + byte*2;
 104     unsigned char val = ival;
 105     int counter = 0;
 106     unsigned char *dest_end = dest + dest_len;
 107
 108     unsigned char bits = *ptr++;
 109
 110     while ( val != 0x16 ) {
 111         if ( (1 << counter) & bits )
 112             val = src[byte + val - 0x17];
 113         else
 114             val = src[val - 0x17];
 115
 116         if ( val < 0x16 ) {
 117             if (dest + 1 > dest_end)
 118                 return 0;
 119             *dest++ = val;
 120             val = ival;
 121         }
 122
 123         if (counter++ == 7) {
 124             counter = 0;
 125             bits = *ptr++;
 126         }
 127     }
 128
 129     return 0;
 130 }
 131
 132 static void xan_unpack(unsigned char *dest, const unsigned char *src, int dest_len)
 133 {
 134     unsigned char opcode;
 135     int size;
 136     int offset;
 137     int byte1, byte2, byte3;
 138     unsigned char *dest_end = dest + dest_len;
 139
 140     for (;;) {
 141         opcode = *src++;
 142
 143         if ( (opcode & 0x80) == 0 ) {
 144
 145             offset = *src++;
 146
 147             size = opcode & 3;
 148             if (dest + size > dest_end)
 149                 return;
 150             bytecopy(dest, src, size);  dest += size;  src += size;
 151
 152             size = ((opcode & 0x1c) >> 2) + 3;
 153             if (dest + size > dest_end)
 154                 return;
 155             bytecopy (dest, dest - (((opcode & 0x60) << 3) + offset + 1), size);
 156             dest += size;
 157
 158         } else if ( (opcode & 0x40) == 0 ) {
 159
 160             byte1 = *src++;
 161             byte2 = *src++;
 162
 163             size = byte1 >> 6;
 164             if (dest + size > dest_end)
 165                 return;
 166             bytecopy (dest, src, size);  dest += size;  src += size;
 167
 168             size = (opcode & 0x3f) + 4;
 169             if (dest + size > dest_end)
 170                 return;
 171             bytecopy (dest, dest - (((byte1 & 0x3f) << 8) + byte2 + 1), size);
 172             dest += size;
 173
 174         } else if ( (opcode & 0x20) == 0 ) {
 175
 176             byte1 = *src++;
 177             byte2 = *src++;
 178             byte3 = *src++;
 179
 180             size = opcode & 3;
 181             if (dest + size > dest_end)
 182                 return;
 183             bytecopy (dest, src, size);  dest += size;  src += size;
 184
 185             size = byte3 + 5 + ((opcode & 0xc) << 6);
 186             if (dest + size > dest_end)
 187                 return;
 188             bytecopy (dest,
 189                 dest - ((((opcode & 0x10) >> 4) << 0x10) + 1 + (byte1 << 8) + byte2),
 190                 size);
 191             dest += size;
 192         } else {
 193             size = ((opcode & 0x1f) << 2) + 4;
 194
 195             if (size > 0x70)
 196                 break;
 197
 198             if (dest + size > dest_end)
 199                 return;
 200             bytecopy (dest, src, size);  dest += size;  src += size;
 201         }
 202     }
 203
 204     size = opcode & 3;
 205     bytecopy(dest, src, size);  dest += size;  src += size;
 206 }
 207
 208 static inline void xan_wc3_output_pixel_run(XanContext *s,
 209     const unsigned char *pixel_buffer, int x, int y, int pixel_count)
 210 {
 211     int stride;
 212     int line_inc;
 213     int index;
 214     int current_x;
 215     int width = s->avctx->width;
 216     unsigned char *palette_plane;
 217
 218     palette_plane = s->current_frame.data[0];
 219     stride = s->current_frame.linesize[0];
 220     line_inc = stride - width;
 221     index = y * stride + x;
 222     current_x = x;
 223     while((pixel_count--) && (index < s->frame_size)) {
 224
 225         /* don't do a memcpy() here; keyframes generally copy an entire
 226          * frame of data and the stride needs to be accounted for */
 227         palette_plane[index++] = *pixel_buffer++;
 228
 229         current_x++;
 230         if (current_x >= width) {
 231             index += line_inc;
 232             current_x = 0;
 233         }
 234     }
 235 }
 236
 237 static inline void xan_wc3_copy_pixel_run(XanContext *s,
 238     int x, int y, int pixel_count, int motion_x, int motion_y)
 239 {
 240     int stride;
 241     int line_inc;
 242     int curframe_index, prevframe_index;
 243     int curframe_x, prevframe_x;
 244     int width = s->avctx->width;
 245     unsigned char *palette_plane, *prev_palette_plane;
 246
 247     palette_plane = s->current_frame.data[0];
 248     prev_palette_plane = s->last_frame.data[0];
 249     stride = s->current_frame.linesize[0];
 250     line_inc = stride - width;
 251     curframe_index = y * stride + x;
 252     curframe_x = x;
 253     prevframe_index = (y + motion_y) * stride + x + motion_x;
 254     prevframe_x = x + motion_x;
 255     while((pixel_count--) && (curframe_index < s->frame_size)) {
 256
 257         palette_plane[curframe_index++] =
 258             prev_palette_plane[prevframe_index++];
 259
 260         curframe_x++;
 261         if (curframe_x >= width) {
 262             curframe_index += line_inc;
 263             curframe_x = 0;
 264         }
 265
 266         prevframe_x++;
 267         if (prevframe_x >= width) {
 268             prevframe_index += line_inc;
 269             prevframe_x = 0;
 270         }
 271     }
 272 }
 273
 274 static void xan_wc3_decode_frame(XanContext *s) {
 275
 276     int width = s->avctx->width;
 277     int height = s->avctx->height;
 278     int total_pixels = width * height;
 279     unsigned char opcode;
 280     unsigned char flag = 0;
 281     int size = 0;
 282     int motion_x, motion_y;
 283     int x, y;
 284
 285     unsigned char *opcode_buffer = s->buffer1;
 286     int opcode_buffer_size = s->buffer1_size;
 287     const unsigned char *imagedata_buffer = s->buffer2;
 288
 289     /* pointers to segments inside the compressed chunk */
 290     const unsigned char *huffman_segment;
 291     const unsigned char *size_segment;
 292     const unsigned char *vector_segment;
 293     const unsigned char *imagedata_segment;
 294
 295     huffman_segment =   s->buf + AV_RL16(&s->buf[0]);
 296     size_segment =      s->buf + AV_RL16(&s->buf[2]);
 297     vector_segment =    s->buf + AV_RL16(&s->buf[4]);
 298     imagedata_segment = s->buf + AV_RL16(&s->buf[6]);
 299
 300     xan_huffman_decode(opcode_buffer, huffman_segment, opcode_buffer_size);
 301
 302     if (imagedata_segment[0] == 2)
 303         xan_unpack(s->buffer2, &imagedata_segment[1], s->buffer2_size);
 304     else
 305         imagedata_buffer = &imagedata_segment[1];
 306
 307     /* use the decoded data segments to build the frame */
 308     x = y = 0;
 309     while (total_pixels) {
 310
 311         opcode = *opcode_buffer++;
 312         size = 0;
 313
 314         switch (opcode) {
 315
 316         case 0:
 317             flag ^= 1;
 318             continue;
 319
 320         case 1:
 321         case 2:
 322         case 3:
 323         case 4:
 324         case 5:
 325         case 6:
 326         case 7:
 327         case 8:
 328             size = opcode;
 329             break;
 330
 331         case 12:
 332         case 13:
 333         case 14:
 334         case 15:
 335         case 16:
 336         case 17:
 337         case 18:
 338             size += (opcode - 10);
 339             break;
 340
 341         case 9:
 342         case 19:
 343             size = *size_segment++;
 344             break;
 345
 346         case 10:
 347         case 20:
 348             size = AV_RB16(&size_segment[0]);
 349             size_segment += 2;
 350             break;
 351
 352         case 11:
 353         case 21:
 354             size = AV_RB24(size_segment);
 355             size_segment += 3;
 356             break;
 357         }
 358
 359         if (opcode < 12) {
 360             flag ^= 1;
 361             if (flag) {
 362                 /* run of (size) pixels is unchanged from last frame */
 363                 xan_wc3_copy_pixel_run(s, x, y, size, 0, 0);
 364             } else {
 365                 /* output a run of pixels from imagedata_buffer */
 366                 xan_wc3_output_pixel_run(s, imagedata_buffer, x, y, size);
 367                 imagedata_buffer += size;
 368             }
 369         } else {
 370             /* run-based motion compensation from last frame */
 371             motion_x = (*vector_segment >> 4) & 0xF;
 372             motion_y = *vector_segment & 0xF;
 373             vector_segment++;
 374
 375             /* sign extension */
 376             if (motion_x & 0x8)
 377                 motion_x |= 0xFFFFFFF0;
 378             if (motion_y & 0x8)
 379                 motion_y |= 0xFFFFFFF0;
 380
 381             /* copy a run of pixels from the previous frame */
 382             xan_wc3_copy_pixel_run(s, x, y, size, motion_x, motion_y);
 383
 384             flag = 0;
 385         }
 386
 387         /* coordinate accounting */
 388         total_pixels -= size;
 389         while (size) {
 390             if (x + size >= width) {
 391                 y++;
 392                 size -= (width - x);
 393                 x = 0;
 394             } else {
 395                 x += size;
 396                 size = 0;
 397             }
 398         }
 399     }
 400 }
 401
 402 static void xan_wc4_decode_frame(XanContext *s) {
 403 }
 404
 405 static int xan_decode_frame(AVCodecContext *avctx,
 406                             void *data, int *data_size,
 407                             const uint8_t *buf, int buf_size)
 408 {
 409     XanContext *s = avctx->priv_data;
 410     AVPaletteControl *palette_control = avctx->palctrl;
 411
 412     if (avctx->get_buffer(avctx, &s->current_frame)) {
 413         av_log(s->avctx, AV_LOG_ERROR, "  Xan Video: get_buffer() failed\n");
 414         return -1;
 415     }
 416     s->current_frame.reference = 3;
 417
 418     if (!s->frame_size)
 419         s->frame_size = s->current_frame.linesize[0] * s->avctx->height;
 420
 421     palette_control->palette_changed = 0;
 422     memcpy(s->current_frame.data[1], palette_control->palette,
 423         AVPALETTE_SIZE);
 424     s->current_frame.palette_has_changed = 1;
 425
 426     s->buf = buf;
 427     s->size = buf_size;
 428
 429     if (avctx->codec->id == CODEC_ID_XAN_WC3)
 430         xan_wc3_decode_frame(s);
 431     else if (avctx->codec->id == CODEC_ID_XAN_WC4)
 432         xan_wc4_decode_frame(s);
 433
 434     /* release the last frame if it is allocated */
 435     if (s->last_frame.data[0])
 436         avctx->release_buffer(avctx, &s->last_frame);
 437
 438     *data_size = sizeof(AVFrame);
 439     *(AVFrame*)data = s->current_frame;
 440
 441     /* shuffle frames */
 442     FFSWAP(AVFrame, s->current_frame, s->last_frame);
 443
 444     /* always report that the buffer was completely consumed */
 445     return buf_size;
 446 }
 447
 448 static av_cold int xan_decode_end(AVCodecContext *avctx)
 449 {
 450     XanContext *s = avctx->priv_data;
 451
 452     /* release the frames */
 453     if (s->last_frame.data[0])
 454         avctx->release_buffer(avctx, &s->last_frame);
 455     if (s->current_frame.data[0])
 456         avctx->release_buffer(avctx, &s->current_frame);
 457
 458     av_free(s->buffer1);
 459     av_free(s->buffer2);
 460
 461     return 0;
 462 }
 463
 464 AVCodec xan_wc3_decoder = {
 465     "xan_wc3",
 466     CODEC_TYPE_VIDEO,
 467     CODEC_ID_XAN_WC3,
 468     sizeof(XanContext),
 469     xan_decode_init,
 470     NULL,
 471     xan_decode_end,
 472     xan_decode_frame,
 473     CODEC_CAP_DR1,
 474     .long_name = NULL_IF_CONFIG_SMALL("Wing Commander III / Xan"),
 475 };
 476
 477 /*
 478 AVCodec xan_wc4_decoder = {
 479     "xan_wc4",
 480     CODEC_TYPE_VIDEO,
 481     CODEC_ID_XAN_WC4,
 482     sizeof(XanContext),
 483     xan_decode_init,
 484     NULL,
 485     xan_decode_end,
 486     xan_decode_frame,
 487     CODEC_CAP_DR1,
 488 };
 489 */