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 libavcodec/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 "libavutil/intreadwrite.h"
  37 #include "avcodec.h"
  38
  39 typedef struct XanContext {
  40
  41     AVCodecContext *avctx;
  42     AVFrame last_frame;
  43     AVFrame current_frame;
  44
  45     const unsigned char *buf;
  46     int size;
  47
  48     /* scratch space */
  49     unsigned char *buffer1;
  50     int buffer1_size;
  51     unsigned char *buffer2;
  52     int buffer2_size;
  53
  54     int frame_size;
  55
  56 } XanContext;
  57
  58 static av_cold int xan_decode_init(AVCodecContext *avctx)
  59 {
  60     XanContext *s = avctx->priv_data;
  61
  62     s->avctx = avctx;
  63     s->frame_size = 0;
  64
  65     if ((avctx->codec->id == CODEC_ID_XAN_WC3) &&
  66         (s->avctx->palctrl == NULL)) {
  67         av_log(avctx, AV_LOG_ERROR, " WC3 Xan video: palette expected.\n");
  68         return -1;
  69     }
  70
  71     avctx->pix_fmt = PIX_FMT_PAL8;
  72
  73     if(avcodec_check_dimensions(avctx, avctx->width, avctx->height))
  74         return -1;
  75
  76     s->buffer1_size = avctx->width * avctx->height;
  77     s->buffer1 = av_malloc(s->buffer1_size);
  78     s->buffer2_size = avctx->width * avctx->height;
  79     s->buffer2 = av_malloc(s->buffer2_size);
  80     if (!s->buffer1 || !s->buffer2)
  81         return -1;
  82
  83     return 0;
  84 }
  85
  86 /* This function is used in lieu of memcpy(). This decoder cannot use
  87  * memcpy because the memory locations often overlap and
  88  * memcpy doesn't like that; it's not uncommon, for example, for
  89  * dest = src+1, to turn byte A into  pattern AAAAAAAA.
  90  * This was originally repz movsb in Intel x86 ASM. */
  91 static inline void bytecopy(unsigned char *dest, const unsigned char *src, int count)
  92 {
  93     int i;
  94
  95     for (i = 0; i < count; i++)
  96         dest[i] = src[i];
  97 }
  98
  99 static int xan_huffman_decode(unsigned char *dest, const unsigned char *src,
 100     int dest_len)
 101 {
 102     unsigned char byte = *src++;
 103     unsigned char ival = byte + 0x16;
 104     const unsigned char * ptr = src + byte*2;
 105     unsigned char val = ival;
 106     int counter = 0;
 107     unsigned char *dest_end = dest + dest_len;
 108
 109     unsigned char bits = *ptr++;
 110
 111     while ( val != 0x16 ) {
 112         if ( (1 << counter) & bits )
 113             val = src[byte + val - 0x17];
 114         else
 115             val = src[val - 0x17];
 116
 117         if ( val < 0x16 ) {
 118             if (dest + 1 > dest_end)
 119                 return 0;
 120             *dest++ = val;
 121             val = ival;
 122         }
 123
 124         if (counter++ == 7) {
 125             counter = 0;
 126             bits = *ptr++;
 127         }
 128     }
 129
 130     return 0;
 131 }
 132
 133 static void xan_unpack(unsigned char *dest, const unsigned char *src, int dest_len)
 134 {
 135     unsigned char opcode;
 136     int size;
 137     int offset;
 138     int byte1, byte2, byte3;
 139     unsigned char *dest_end = dest + dest_len;
 140
 141     for (;;) {
 142         opcode = *src++;
 143
 144         if ( (opcode & 0x80) == 0 ) {
 145
 146             offset = *src++;
 147
 148             size = opcode & 3;
 149             if (dest + size > dest_end)
 150                 return;
 151             bytecopy(dest, src, size);  dest += size;  src += size;
 152
 153             size = ((opcode & 0x1c) >> 2) + 3;
 154             if (dest + size > dest_end)
 155                 return;
 156             bytecopy (dest, dest - (((opcode & 0x60) << 3) + offset + 1), size);
 157             dest += size;
 158
 159         } else if ( (opcode & 0x40) == 0 ) {
 160
 161             byte1 = *src++;
 162             byte2 = *src++;
 163
 164             size = byte1 >> 6;
 165             if (dest + size > dest_end)
 166                 return;
 167             bytecopy (dest, src, size);  dest += size;  src += size;
 168
 169             size = (opcode & 0x3f) + 4;
 170             if (dest + size > dest_end)
 171                 return;
 172             bytecopy (dest, dest - (((byte1 & 0x3f) << 8) + byte2 + 1), size);
 173             dest += size;
 174
 175         } else if ( (opcode & 0x20) == 0 ) {
 176
 177             byte1 = *src++;
 178             byte2 = *src++;
 179             byte3 = *src++;
 180
 181             size = opcode & 3;
 182             if (dest + size > dest_end)
 183                 return;
 184             bytecopy (dest, src, size);  dest += size;  src += size;
 185
 186             size = byte3 + 5 + ((opcode & 0xc) << 6);
 187             if (dest + size > dest_end)
 188                 return;
 189             bytecopy (dest,
 190                 dest - ((((opcode & 0x10) >> 4) << 0x10) + 1 + (byte1 << 8) + byte2),
 191                 size);
 192             dest += size;
 193         } else {
 194             size = ((opcode & 0x1f) << 2) + 4;
 195
 196             if (size > 0x70)
 197                 break;
 198
 199             if (dest + size > dest_end)
 200                 return;
 201             bytecopy (dest, src, size);  dest += size;  src += size;
 202         }
 203     }
 204
 205     size = opcode & 3;
 206     bytecopy(dest, src, size);  dest += size;  src += size;
 207 }
 208
 209 static inline void xan_wc3_output_pixel_run(XanContext *s,
 210     const unsigned char *pixel_buffer, int x, int y, int pixel_count)
 211 {
 212     int stride;
 213     int line_inc;
 214     int index;
 215     int current_x;
 216     int width = s->avctx->width;
 217     unsigned char *palette_plane;
 218
 219     palette_plane = s->current_frame.data[0];
 220     stride = s->current_frame.linesize[0];
 221     line_inc = stride - width;
 222     index = y * stride + x;
 223     current_x = x;
 224     while((pixel_count--) && (index < s->frame_size)) {
 225
 226         /* don't do a memcpy() here; keyframes generally copy an entire
 227          * frame of data and the stride needs to be accounted for */
 228         palette_plane[index++] = *pixel_buffer++;
 229
 230         current_x++;
 231         if (current_x >= width) {
 232             index += line_inc;
 233             current_x = 0;
 234         }
 235     }
 236 }
 237
 238 static inline void xan_wc3_copy_pixel_run(XanContext *s,
 239     int x, int y, int pixel_count, int motion_x, int motion_y)
 240 {
 241     int stride;
 242     int line_inc;
 243     int curframe_index, prevframe_index;
 244     int curframe_x, prevframe_x;
 245     int width = s->avctx->width;
 246     unsigned char *palette_plane, *prev_palette_plane;
 247
 248     palette_plane = s->current_frame.data[0];
 249     prev_palette_plane = s->last_frame.data[0];
 250     stride = s->current_frame.linesize[0];
 251     line_inc = stride - width;
 252     curframe_index = y * stride + x;
 253     curframe_x = x;
 254     prevframe_index = (y + motion_y) * stride + x + motion_x;
 255     prevframe_x = x + motion_x;
 256     while((pixel_count--) && (curframe_index < s->frame_size)) {
 257
 258         palette_plane[curframe_index++] =
 259             prev_palette_plane[prevframe_index++];
 260
 261         curframe_x++;
 262         if (curframe_x >= width) {
 263             curframe_index += line_inc;
 264             curframe_x = 0;
 265         }
 266
 267         prevframe_x++;
 268         if (prevframe_x >= width) {
 269             prevframe_index += line_inc;
 270             prevframe_x = 0;
 271         }
 272     }
 273 }
 274
 275 static void xan_wc3_decode_frame(XanContext *s) {
 276
 277     int width = s->avctx->width;
 278     int height = s->avctx->height;
 279     int total_pixels = width * height;
 280     unsigned char opcode;
 281     unsigned char flag = 0;
 282     int size = 0;
 283     int motion_x, motion_y;
 284     int x, y;
 285
 286     unsigned char *opcode_buffer = s->buffer1;
 287     int opcode_buffer_size = s->buffer1_size;
 288     const unsigned char *imagedata_buffer = s->buffer2;
 289
 290     /* pointers to segments inside the compressed chunk */
 291     const unsigned char *huffman_segment;
 292     const unsigned char *size_segment;
 293     const unsigned char *vector_segment;
 294     const unsigned char *imagedata_segment;
 295
 296     huffman_segment =   s->buf + AV_RL16(&s->buf[0]);
 297     size_segment =      s->buf + AV_RL16(&s->buf[2]);
 298     vector_segment =    s->buf + AV_RL16(&s->buf[4]);
 299     imagedata_segment = s->buf + AV_RL16(&s->buf[6]);
 300
 301     xan_huffman_decode(opcode_buffer, huffman_segment, opcode_buffer_size);
 302
 303     if (imagedata_segment[0] == 2)
 304         xan_unpack(s->buffer2, &imagedata_segment[1], s->buffer2_size);
 305     else
 306         imagedata_buffer = &imagedata_segment[1];
 307
 308     /* use the decoded data segments to build the frame */
 309     x = y = 0;
 310     while (total_pixels) {
 311
 312         opcode = *opcode_buffer++;
 313         size = 0;
 314
 315         switch (opcode) {
 316
 317         case 0:
 318             flag ^= 1;
 319             continue;
 320
 321         case 1:
 322         case 2:
 323         case 3:
 324         case 4:
 325         case 5:
 326         case 6:
 327         case 7:
 328         case 8:
 329             size = opcode;
 330             break;
 331
 332         case 12:
 333         case 13:
 334         case 14:
 335         case 15:
 336         case 16:
 337         case 17:
 338         case 18:
 339             size += (opcode - 10);
 340             break;
 341
 342         case 9:
 343         case 19:
 344             size = *size_segment++;
 345             break;
 346
 347         case 10:
 348         case 20:
 349             size = AV_RB16(&size_segment[0]);
 350             size_segment += 2;
 351             break;
 352
 353         case 11:
 354         case 21:
 355             size = AV_RB24(size_segment);
 356             size_segment += 3;
 357             break;
 358         }
 359
 360         if (opcode < 12) {
 361             flag ^= 1;
 362             if (flag) {
 363                 /* run of (size) pixels is unchanged from last frame */
 364                 xan_wc3_copy_pixel_run(s, x, y, size, 0, 0);
 365             } else {
 366                 /* output a run of pixels from imagedata_buffer */
 367                 xan_wc3_output_pixel_run(s, imagedata_buffer, x, y, size);
 368                 imagedata_buffer += size;
 369             }
 370         } else {
 371             /* run-based motion compensation from last frame */
 372             motion_x = (*vector_segment >> 4) & 0xF;
 373             motion_y = *vector_segment & 0xF;
 374             vector_segment++;
 375
 376             /* sign extension */
 377             if (motion_x & 0x8)
 378                 motion_x |= 0xFFFFFFF0;
 379             if (motion_y & 0x8)
 380                 motion_y |= 0xFFFFFFF0;
 381
 382             /* copy a run of pixels from the previous frame */
 383             xan_wc3_copy_pixel_run(s, x, y, size, motion_x, motion_y);
 384
 385             flag = 0;
 386         }
 387
 388         /* coordinate accounting */
 389         total_pixels -= size;
 390         while (size) {
 391             if (x + size >= width) {
 392                 y++;
 393                 size -= (width - x);
 394                 x = 0;
 395             } else {
 396                 x += size;
 397                 size = 0;
 398             }
 399         }
 400     }
 401 }
 402
 403 static void xan_wc4_decode_frame(XanContext *s) {
 404 }
 405
 406 static int xan_decode_frame(AVCodecContext *avctx,
 407                             void *data, int *data_size,
 408                             const uint8_t *buf, int buf_size)
 409 {
 410     XanContext *s = avctx->priv_data;
 411     AVPaletteControl *palette_control = avctx->palctrl;
 412
 413     if (avctx->get_buffer(avctx, &s->current_frame)) {
 414         av_log(s->avctx, AV_LOG_ERROR, "  Xan Video: get_buffer() failed\n");
 415         return -1;
 416     }
 417     s->current_frame.reference = 3;
 418
 419     if (!s->frame_size)
 420         s->frame_size = s->current_frame.linesize[0] * s->avctx->height;
 421
 422     palette_control->palette_changed = 0;
 423     memcpy(s->current_frame.data[1], palette_control->palette,
 424         AVPALETTE_SIZE);
 425     s->current_frame.palette_has_changed = 1;
 426
 427     s->buf = buf;
 428     s->size = buf_size;
 429
 430     if (avctx->codec->id == CODEC_ID_XAN_WC3)
 431         xan_wc3_decode_frame(s);
 432     else if (avctx->codec->id == CODEC_ID_XAN_WC4)
 433         xan_wc4_decode_frame(s);
 434
 435     /* release the last frame if it is allocated */
 436     if (s->last_frame.data[0])
 437         avctx->release_buffer(avctx, &s->last_frame);
 438
 439     *data_size = sizeof(AVFrame);
 440     *(AVFrame*)data = s->current_frame;
 441
 442     /* shuffle frames */
 443     FFSWAP(AVFrame, s->current_frame, s->last_frame);
 444
 445     /* always report that the buffer was completely consumed */
 446     return buf_size;
 447 }
 448
 449 static av_cold int xan_decode_end(AVCodecContext *avctx)
 450 {
 451     XanContext *s = avctx->priv_data;
 452
 453     /* release the frames */
 454     if (s->last_frame.data[0])
 455         avctx->release_buffer(avctx, &s->last_frame);
 456     if (s->current_frame.data[0])
 457         avctx->release_buffer(avctx, &s->current_frame);
 458
 459     av_free(s->buffer1);
 460     av_free(s->buffer2);
 461
 462     return 0;
 463 }
 464
 465 AVCodec xan_wc3_decoder = {
 466     "xan_wc3",
 467     CODEC_TYPE_VIDEO,
 468     CODEC_ID_XAN_WC3,
 469     sizeof(XanContext),
 470     xan_decode_init,
 471     NULL,
 472     xan_decode_end,
 473     xan_decode_frame,
 474     CODEC_CAP_DR1,
 475     .long_name = NULL_IF_CONFIG_SMALL("Wing Commander III / Xan"),
 476 };
 477
 478 /*
 479 AVCodec xan_wc4_decoder = {
 480     "xan_wc4",
 481     CODEC_TYPE_VIDEO,
 482     CODEC_ID_XAN_WC4,
 483     sizeof(XanContext),
 484     xan_decode_init,
 485     NULL,
 486     xan_decode_end,
 487     xan_decode_frame,
 488     CODEC_CAP_DR1,
 489 };
 490 */