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
  35 #include "libavutil/intreadwrite.h"
  36 #include "avcodec.h"
  37 #include "bytestream.h"
  38 #define ALT_BITSTREAM_READER_LE
  39 #include "get_bits.h"
  40 // for av_memcpy_backptr
  41 #include "libavutil/lzo.h"
  42
  43 typedef struct XanContext {
  44
  45     AVCodecContext *avctx;
  46     AVFrame last_frame;
  47     AVFrame current_frame;
  48
  49     const unsigned char *buf;
  50     int size;
  51
  52     /* scratch space */
  53     unsigned char *buffer1;
  54     int buffer1_size;
  55     unsigned char *buffer2;
  56     int buffer2_size;
  57
  58     int frame_size;
  59
  60 } XanContext;
  61
  62 static av_cold int xan_decode_init(AVCodecContext *avctx)
  63 {
  64     XanContext *s = avctx->priv_data;
  65
  66     s->avctx = avctx;
  67     s->frame_size = 0;
  68
  69     if ((avctx->codec->id == CODEC_ID_XAN_WC3) &&
  70         (s->avctx->palctrl == NULL)) {
  71         av_log(avctx, AV_LOG_ERROR, " WC3 Xan video: palette expected.\n");
  72         return -1;
  73     }
  74
  75     avctx->pix_fmt = PIX_FMT_PAL8;
  76
  77     if(avcodec_check_dimensions(avctx, avctx->width, avctx->height))
  78         return -1;
  79
  80     s->buffer1_size = avctx->width * avctx->height;
  81     s->buffer1 = av_malloc(s->buffer1_size);
  82     s->buffer2_size = avctx->width * avctx->height;
  83     s->buffer2 = av_malloc(s->buffer2_size + 130);
  84     if (!s->buffer1 || !s->buffer2)
  85         return -1;
  86
  87     return 0;
  88 }
  89
  90 static int xan_huffman_decode(unsigned char *dest, const unsigned char *src,
  91     int dest_len)
  92 {
  93     unsigned char byte = *src++;
  94     unsigned char ival = byte + 0x16;
  95     const unsigned char * ptr = src + byte*2;
  96     unsigned char val = ival;
  97     unsigned char *dest_end = dest + dest_len;
  98     GetBitContext gb;
  99
 100     init_get_bits(&gb, ptr, 0); // FIXME: no src size available
 101
 102     while ( val != 0x16 ) {
 103         val = src[val - 0x17 + get_bits1(&gb) * byte];
 104
 105         if ( val < 0x16 ) {
 106             if (dest >= dest_end)
 107                 return 0;
 108             *dest++ = val;
 109             val = ival;
 110         }
 111     }
 112
 113     return 0;
 114 }
 115
 116 /**
 117  * unpack simple compression
 118  *
 119  * @param dest destination buffer of dest_len, must be padded with at least 130 bytes
 120  */
 121 static void xan_unpack(unsigned char *dest, const unsigned char *src, int dest_len)
 122 {
 123     unsigned char opcode;
 124     int size;
 125     unsigned char *dest_end = dest + dest_len;
 126
 127     while (dest < dest_end) {
 128         opcode = *src++;
 129
 130         if (opcode < 0xe0) {
 131             int size2, back;
 132             if ( (opcode & 0x80) == 0 ) {
 133
 134                 size = opcode & 3;
 135
 136                 back  = ((opcode & 0x60) << 3) + *src++ + 1;
 137                 size2 = ((opcode & 0x1c) >> 2) + 3;
 138
 139             } else if ( (opcode & 0x40) == 0 ) {
 140
 141                 size = *src >> 6;
 142
 143                 back  = (bytestream_get_be16(&src) & 0x3fff) + 1;
 144                 size2 = (opcode & 0x3f) + 4;
 145
 146             } else {
 147
 148                 size = opcode & 3;
 149
 150                 back  = ((opcode & 0x10) << 12) + bytestream_get_be16(&src) + 1;
 151                 size2 = ((opcode & 0x0c) <<  6) + *src++ + 5;
 152                 if (size + size2 > dest_end - dest)
 153                     return;
 154             }
 155             memcpy(dest, src, size);  dest += size;  src += size;
 156             av_memcpy_backptr(dest, back, size2);
 157             dest += size2;
 158         } else {
 159             int finish;
 160             size = ((opcode & 0x1f) << 2) + 4;
 161
 162             finish = size > 0x70;
 163             if (finish)
 164                 size = opcode & 3;
 165
 166             memcpy(dest, src, size);  dest += size;  src += size;
 167             if (finish)
 168                 return;
 169         }
 170     }
 171 }
 172
 173 static inline void xan_wc3_output_pixel_run(XanContext *s,
 174     const unsigned char *pixel_buffer, int x, int y, int pixel_count)
 175 {
 176     int stride;
 177     int line_inc;
 178     int index;
 179     int current_x;
 180     int width = s->avctx->width;
 181     unsigned char *palette_plane;
 182
 183     palette_plane = s->current_frame.data[0];
 184     stride = s->current_frame.linesize[0];
 185     line_inc = stride - width;
 186     index = y * stride + x;
 187     current_x = x;
 188     while((pixel_count--) && (index < s->frame_size)) {
 189
 190         /* don't do a memcpy() here; keyframes generally copy an entire
 191          * frame of data and the stride needs to be accounted for */
 192         palette_plane[index++] = *pixel_buffer++;
 193
 194         current_x++;
 195         if (current_x >= width) {
 196             index += line_inc;
 197             current_x = 0;
 198         }
 199     }
 200 }
 201
 202 static inline void xan_wc3_copy_pixel_run(XanContext *s,
 203     int x, int y, int pixel_count, int motion_x, int motion_y)
 204 {
 205     int stride;
 206     int line_inc;
 207     int curframe_index, prevframe_index;
 208     int curframe_x, prevframe_x;
 209     int width = s->avctx->width;
 210     unsigned char *palette_plane, *prev_palette_plane;
 211
 212     palette_plane = s->current_frame.data[0];
 213     prev_palette_plane = s->last_frame.data[0];
 214     stride = s->current_frame.linesize[0];
 215     line_inc = stride - width;
 216     curframe_index = y * stride + x;
 217     curframe_x = x;
 218     prevframe_index = (y + motion_y) * stride + x + motion_x;
 219     prevframe_x = x + motion_x;
 220     while((pixel_count--) && (curframe_index < s->frame_size)) {
 221
 222         palette_plane[curframe_index++] =
 223             prev_palette_plane[prevframe_index++];
 224
 225         curframe_x++;
 226         if (curframe_x >= width) {
 227             curframe_index += line_inc;
 228             curframe_x = 0;
 229         }
 230
 231         prevframe_x++;
 232         if (prevframe_x >= width) {
 233             prevframe_index += line_inc;
 234             prevframe_x = 0;
 235         }
 236     }
 237 }
 238
 239 static void xan_wc3_decode_frame(XanContext *s) {
 240
 241     int width = s->avctx->width;
 242     int height = s->avctx->height;
 243     int total_pixels = width * height;
 244     unsigned char opcode;
 245     unsigned char flag = 0;
 246     int size = 0;
 247     int motion_x, motion_y;
 248     int x, y;
 249
 250     unsigned char *opcode_buffer = s->buffer1;
 251     int opcode_buffer_size = s->buffer1_size;
 252     const unsigned char *imagedata_buffer = s->buffer2;
 253
 254     /* pointers to segments inside the compressed chunk */
 255     const unsigned char *huffman_segment;
 256     const unsigned char *size_segment;
 257     const unsigned char *vector_segment;
 258     const unsigned char *imagedata_segment;
 259
 260     huffman_segment =   s->buf + AV_RL16(&s->buf[0]);
 261     size_segment =      s->buf + AV_RL16(&s->buf[2]);
 262     vector_segment =    s->buf + AV_RL16(&s->buf[4]);
 263     imagedata_segment = s->buf + AV_RL16(&s->buf[6]);
 264
 265     xan_huffman_decode(opcode_buffer, huffman_segment, opcode_buffer_size);
 266
 267     if (imagedata_segment[0] == 2)
 268         xan_unpack(s->buffer2, &imagedata_segment[1], s->buffer2_size);
 269     else
 270         imagedata_buffer = &imagedata_segment[1];
 271
 272     /* use the decoded data segments to build the frame */
 273     x = y = 0;
 274     while (total_pixels) {
 275
 276         opcode = *opcode_buffer++;
 277         size = 0;
 278
 279         switch (opcode) {
 280
 281         case 0:
 282             flag ^= 1;
 283             continue;
 284
 285         case 1:
 286         case 2:
 287         case 3:
 288         case 4:
 289         case 5:
 290         case 6:
 291         case 7:
 292         case 8:
 293             size = opcode;
 294             break;
 295
 296         case 12:
 297         case 13:
 298         case 14:
 299         case 15:
 300         case 16:
 301         case 17:
 302         case 18:
 303             size += (opcode - 10);
 304             break;
 305
 306         case 9:
 307         case 19:
 308             size = *size_segment++;
 309             break;
 310
 311         case 10:
 312         case 20:
 313             size = AV_RB16(&size_segment[0]);
 314             size_segment += 2;
 315             break;
 316
 317         case 11:
 318         case 21:
 319             size = AV_RB24(size_segment);
 320             size_segment += 3;
 321             break;
 322         }
 323
 324         if (opcode < 12) {
 325             flag ^= 1;
 326             if (flag) {
 327                 /* run of (size) pixels is unchanged from last frame */
 328                 xan_wc3_copy_pixel_run(s, x, y, size, 0, 0);
 329             } else {
 330                 /* output a run of pixels from imagedata_buffer */
 331                 xan_wc3_output_pixel_run(s, imagedata_buffer, x, y, size);
 332                 imagedata_buffer += size;
 333             }
 334         } else {
 335             /* run-based motion compensation from last frame */
 336             motion_x = sign_extend(*vector_segment >> 4,  4);
 337             motion_y = sign_extend(*vector_segment & 0xF, 4);
 338             vector_segment++;
 339
 340             /* copy a run of pixels from the previous frame */
 341             xan_wc3_copy_pixel_run(s, x, y, size, motion_x, motion_y);
 342
 343             flag = 0;
 344         }
 345
 346         /* coordinate accounting */
 347         total_pixels -= size;
 348         y += (x + size) / width;
 349         x  = (x + size) % width;
 350     }
 351 }
 352
 353 static void xan_wc4_decode_frame(XanContext *s) {
 354 }
 355
 356 static int xan_decode_frame(AVCodecContext *avctx,
 357                             void *data, int *data_size,
 358                             AVPacket *avpkt)
 359 {
 360     const uint8_t *buf = avpkt->data;
 361     int buf_size = avpkt->size;
 362     XanContext *s = avctx->priv_data;
 363     AVPaletteControl *palette_control = avctx->palctrl;
 364
 365     if (avctx->get_buffer(avctx, &s->current_frame)) {
 366         av_log(s->avctx, AV_LOG_ERROR, "  Xan Video: get_buffer() failed\n");
 367         return -1;
 368     }
 369     s->current_frame.reference = 3;
 370
 371     if (!s->frame_size)
 372         s->frame_size = s->current_frame.linesize[0] * s->avctx->height;
 373
 374     palette_control->palette_changed = 0;
 375     memcpy(s->current_frame.data[1], palette_control->palette,
 376         AVPALETTE_SIZE);
 377     s->current_frame.palette_has_changed = 1;
 378
 379     s->buf = buf;
 380     s->size = buf_size;
 381
 382     if (avctx->codec->id == CODEC_ID_XAN_WC3)
 383         xan_wc3_decode_frame(s);
 384     else if (avctx->codec->id == CODEC_ID_XAN_WC4)
 385         xan_wc4_decode_frame(s);
 386
 387     /* release the last frame if it is allocated */
 388     if (s->last_frame.data[0])
 389         avctx->release_buffer(avctx, &s->last_frame);
 390
 391     *data_size = sizeof(AVFrame);
 392     *(AVFrame*)data = s->current_frame;
 393
 394     /* shuffle frames */
 395     FFSWAP(AVFrame, s->current_frame, s->last_frame);
 396
 397     /* always report that the buffer was completely consumed */
 398     return buf_size;
 399 }
 400
 401 static av_cold int xan_decode_end(AVCodecContext *avctx)
 402 {
 403     XanContext *s = avctx->priv_data;
 404
 405     /* release the frames */
 406     if (s->last_frame.data[0])
 407         avctx->release_buffer(avctx, &s->last_frame);
 408     if (s->current_frame.data[0])
 409         avctx->release_buffer(avctx, &s->current_frame);
 410
 411     av_free(s->buffer1);
 412     av_free(s->buffer2);
 413
 414     return 0;
 415 }
 416
 417 AVCodec xan_wc3_decoder = {
 418     "xan_wc3",
 419     CODEC_TYPE_VIDEO,
 420     CODEC_ID_XAN_WC3,
 421     sizeof(XanContext),
 422     xan_decode_init,
 423     NULL,
 424     xan_decode_end,
 425     xan_decode_frame,
 426     CODEC_CAP_DR1,
 427     .long_name = NULL_IF_CONFIG_SMALL("Wing Commander III / Xan"),
 428 };
 429
 430 /*
 431 AVCodec xan_wc4_decoder = {
 432     "xan_wc4",
 433     CODEC_TYPE_VIDEO,
 434     CODEC_ID_XAN_WC4,
 435     sizeof(XanContext),
 436     xan_decode_init,
 437     NULL,
 438     xan_decode_end,
 439     xan_decode_frame,
 440     CODEC_CAP_DR1,
 441 };
 442 */