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 #include "bytestream.h"
  39 #define ALT_BITSTREAM_READER_LE
  40 #include "get_bits.h"
  41 // for av_memcpy_backptr
  42 #include "libavutil/lzo.h"
  43
  44 typedef struct XanContext {
  45
  46     AVCodecContext *avctx;
  47     AVFrame last_frame;
  48     AVFrame current_frame;
  49
  50     const unsigned char *buf;
  51     int size;
  52
  53     /* scratch space */
  54     unsigned char *buffer1;
  55     int buffer1_size;
  56     unsigned char *buffer2;
  57     int buffer2_size;
  58
  59     int frame_size;
  60
  61 } XanContext;
  62
  63 static av_cold int xan_decode_init(AVCodecContext *avctx)
  64 {
  65     XanContext *s = avctx->priv_data;
  66
  67     s->avctx = avctx;
  68     s->frame_size = 0;
  69
  70     if ((avctx->codec->id == CODEC_ID_XAN_WC3) &&
  71         (s->avctx->palctrl == NULL)) {
  72         av_log(avctx, AV_LOG_ERROR, " WC3 Xan video: palette expected.\n");
  73         return -1;
  74     }
  75
  76     avctx->pix_fmt = PIX_FMT_PAL8;
  77
  78     if(avcodec_check_dimensions(avctx, avctx->width, avctx->height))
  79         return -1;
  80
  81     s->buffer1_size = avctx->width * avctx->height;
  82     s->buffer1 = av_malloc(s->buffer1_size);
  83     s->buffer2_size = avctx->width * avctx->height;
  84     s->buffer2 = av_malloc(s->buffer2_size + 130);
  85     if (!s->buffer1 || !s->buffer2)
  86         return -1;
  87
  88     return 0;
  89 }
  90
  91 static int xan_huffman_decode(unsigned char *dest, const unsigned char *src,
  92     int dest_len)
  93 {
  94     unsigned char byte = *src++;
  95     unsigned char ival = byte + 0x16;
  96     const unsigned char * ptr = src + byte*2;
  97     unsigned char val = ival;
  98     unsigned char *dest_end = dest + dest_len;
  99     GetBitContext gb;
 100
 101     init_get_bits(&gb, ptr, 0); // FIXME: no src size available
 102
 103     while ( val != 0x16 ) {
 104         val = src[val - 0x17 + get_bits1(&gb) * byte];
 105
 106         if ( val < 0x16 ) {
 107             if (dest >= dest_end)
 108                 return 0;
 109             *dest++ = val;
 110             val = ival;
 111         }
 112     }
 113
 114     return 0;
 115 }
 116
 117 /**
 118  * unpack simple compression
 119  *
 120  * @param dest destination buffer of dest_len, must be padded with at least 130 bytes
 121  */
 122 static void xan_unpack(unsigned char *dest, const unsigned char *src, int dest_len)
 123 {
 124     unsigned char opcode;
 125     int size;
 126     unsigned char *dest_end = dest + dest_len;
 127
 128     while (dest < dest_end) {
 129         opcode = *src++;
 130
 131         if (opcode < 0xe0) {
 132             int size2, back;
 133             if ( (opcode & 0x80) == 0 ) {
 134
 135                 size = opcode & 3;
 136
 137                 back  = ((opcode & 0x60) << 3) + *src++ + 1;
 138                 size2 = ((opcode & 0x1c) >> 2) + 3;
 139
 140             } else if ( (opcode & 0x40) == 0 ) {
 141
 142                 size = *src >> 6;
 143
 144                 back  = (bytestream_get_be16(&src) & 0x3fff) + 1;
 145                 size2 = (opcode & 0x3f) + 4;
 146
 147             } else {
 148
 149                 size = opcode & 3;
 150
 151                 back  = ((opcode & 0x10) << 12) + bytestream_get_be16(&src) + 1;
 152                 size2 = ((opcode & 0x0c) <<  6) + *src++ + 5;
 153                 if (size + size2 > dest_end - dest)
 154                     return;
 155             }
 156             memcpy(dest, src, size);  dest += size;  src += size;
 157             av_memcpy_backptr(dest, back, size2);
 158             dest += size2;
 159         } else {
 160             int finish;
 161             size = ((opcode & 0x1f) << 2) + 4;
 162
 163             finish = size > 0x70;
 164             if (finish)
 165                 size = opcode & 3;
 166
 167             memcpy(dest, src, size);  dest += size;  src += size;
 168             if (finish)
 169                 return;
 170         }
 171     }
 172 }
 173
 174 static inline void xan_wc3_output_pixel_run(XanContext *s,
 175     const unsigned char *pixel_buffer, int x, int y, int pixel_count)
 176 {
 177     int stride;
 178     int line_inc;
 179     int index;
 180     int current_x;
 181     int width = s->avctx->width;
 182     unsigned char *palette_plane;
 183
 184     palette_plane = s->current_frame.data[0];
 185     stride = s->current_frame.linesize[0];
 186     line_inc = stride - width;
 187     index = y * stride + x;
 188     current_x = x;
 189     while((pixel_count--) && (index < s->frame_size)) {
 190
 191         /* don't do a memcpy() here; keyframes generally copy an entire
 192          * frame of data and the stride needs to be accounted for */
 193         palette_plane[index++] = *pixel_buffer++;
 194
 195         current_x++;
 196         if (current_x >= width) {
 197             index += line_inc;
 198             current_x = 0;
 199         }
 200     }
 201 }
 202
 203 static inline void xan_wc3_copy_pixel_run(XanContext *s,
 204     int x, int y, int pixel_count, int motion_x, int motion_y)
 205 {
 206     int stride;
 207     int line_inc;
 208     int curframe_index, prevframe_index;
 209     int curframe_x, prevframe_x;
 210     int width = s->avctx->width;
 211     unsigned char *palette_plane, *prev_palette_plane;
 212
 213     palette_plane = s->current_frame.data[0];
 214     prev_palette_plane = s->last_frame.data[0];
 215     stride = s->current_frame.linesize[0];
 216     line_inc = stride - width;
 217     curframe_index = y * stride + x;
 218     curframe_x = x;
 219     prevframe_index = (y + motion_y) * stride + x + motion_x;
 220     prevframe_x = x + motion_x;
 221     while((pixel_count--) && (curframe_index < s->frame_size)) {
 222
 223         palette_plane[curframe_index++] =
 224             prev_palette_plane[prevframe_index++];
 225
 226         curframe_x++;
 227         if (curframe_x >= width) {
 228             curframe_index += line_inc;
 229             curframe_x = 0;
 230         }
 231
 232         prevframe_x++;
 233         if (prevframe_x >= width) {
 234             prevframe_index += line_inc;
 235             prevframe_x = 0;
 236         }
 237     }
 238 }
 239
 240 static void xan_wc3_decode_frame(XanContext *s) {
 241
 242     int width = s->avctx->width;
 243     int height = s->avctx->height;
 244     int total_pixels = width * height;
 245     unsigned char opcode;
 246     unsigned char flag = 0;
 247     int size = 0;
 248     int motion_x, motion_y;
 249     int x, y;
 250
 251     unsigned char *opcode_buffer = s->buffer1;
 252     int opcode_buffer_size = s->buffer1_size;
 253     const unsigned char *imagedata_buffer = s->buffer2;
 254
 255     /* pointers to segments inside the compressed chunk */
 256     const unsigned char *huffman_segment;
 257     const unsigned char *size_segment;
 258     const unsigned char *vector_segment;
 259     const unsigned char *imagedata_segment;
 260
 261     huffman_segment =   s->buf + AV_RL16(&s->buf[0]);
 262     size_segment =      s->buf + AV_RL16(&s->buf[2]);
 263     vector_segment =    s->buf + AV_RL16(&s->buf[4]);
 264     imagedata_segment = s->buf + AV_RL16(&s->buf[6]);
 265
 266     xan_huffman_decode(opcode_buffer, huffman_segment, opcode_buffer_size);
 267
 268     if (imagedata_segment[0] == 2)
 269         xan_unpack(s->buffer2, &imagedata_segment[1], s->buffer2_size);
 270     else
 271         imagedata_buffer = &imagedata_segment[1];
 272
 273     /* use the decoded data segments to build the frame */
 274     x = y = 0;
 275     while (total_pixels) {
 276
 277         opcode = *opcode_buffer++;
 278         size = 0;
 279
 280         switch (opcode) {
 281
 282         case 0:
 283             flag ^= 1;
 284             continue;
 285
 286         case 1:
 287         case 2:
 288         case 3:
 289         case 4:
 290         case 5:
 291         case 6:
 292         case 7:
 293         case 8:
 294             size = opcode;
 295             break;
 296
 297         case 12:
 298         case 13:
 299         case 14:
 300         case 15:
 301         case 16:
 302         case 17:
 303         case 18:
 304             size += (opcode - 10);
 305             break;
 306
 307         case 9:
 308         case 19:
 309             size = *size_segment++;
 310             break;
 311
 312         case 10:
 313         case 20:
 314             size = AV_RB16(&size_segment[0]);
 315             size_segment += 2;
 316             break;
 317
 318         case 11:
 319         case 21:
 320             size = AV_RB24(size_segment);
 321             size_segment += 3;
 322             break;
 323         }
 324
 325         if (opcode < 12) {
 326             flag ^= 1;
 327             if (flag) {
 328                 /* run of (size) pixels is unchanged from last frame */
 329                 xan_wc3_copy_pixel_run(s, x, y, size, 0, 0);
 330             } else {
 331                 /* output a run of pixels from imagedata_buffer */
 332                 xan_wc3_output_pixel_run(s, imagedata_buffer, x, y, size);
 333                 imagedata_buffer += size;
 334             }
 335         } else {
 336             /* run-based motion compensation from last frame */
 337             motion_x = sign_extend(*vector_segment >> 4,  4);
 338             motion_y = sign_extend(*vector_segment & 0xF, 4);
 339             vector_segment++;
 340
 341             /* copy a run of pixels from the previous frame */
 342             xan_wc3_copy_pixel_run(s, x, y, size, motion_x, motion_y);
 343
 344             flag = 0;
 345         }
 346
 347         /* coordinate accounting */
 348         total_pixels -= size;
 349         y += (x + size) / width;
 350         x  = (x + size) % width;
 351     }
 352 }
 353
 354 static void xan_wc4_decode_frame(XanContext *s) {
 355 }
 356
 357 static int xan_decode_frame(AVCodecContext *avctx,
 358                             void *data, int *data_size,
 359                             AVPacket *avpkt)
 360 {
 361     const uint8_t *buf = avpkt->data;
 362     int buf_size = avpkt->size;
 363     XanContext *s = avctx->priv_data;
 364     AVPaletteControl *palette_control = avctx->palctrl;
 365
 366     if (avctx->get_buffer(avctx, &s->current_frame)) {
 367         av_log(s->avctx, AV_LOG_ERROR, "  Xan Video: get_buffer() failed\n");
 368         return -1;
 369     }
 370     s->current_frame.reference = 3;
 371
 372     if (!s->frame_size)
 373         s->frame_size = s->current_frame.linesize[0] * s->avctx->height;
 374
 375     palette_control->palette_changed = 0;
 376     memcpy(s->current_frame.data[1], palette_control->palette,
 377         AVPALETTE_SIZE);
 378     s->current_frame.palette_has_changed = 1;
 379
 380     s->buf = buf;
 381     s->size = buf_size;
 382
 383     if (avctx->codec->id == CODEC_ID_XAN_WC3)
 384         xan_wc3_decode_frame(s);
 385     else if (avctx->codec->id == CODEC_ID_XAN_WC4)
 386         xan_wc4_decode_frame(s);
 387
 388     /* release the last frame if it is allocated */
 389     if (s->last_frame.data[0])
 390         avctx->release_buffer(avctx, &s->last_frame);
 391
 392     *data_size = sizeof(AVFrame);
 393     *(AVFrame*)data = s->current_frame;
 394
 395     /* shuffle frames */
 396     FFSWAP(AVFrame, s->current_frame, s->last_frame);
 397
 398     /* always report that the buffer was completely consumed */
 399     return buf_size;
 400 }
 401
 402 static av_cold int xan_decode_end(AVCodecContext *avctx)
 403 {
 404     XanContext *s = avctx->priv_data;
 405
 406     /* release the frames */
 407     if (s->last_frame.data[0])
 408         avctx->release_buffer(avctx, &s->last_frame);
 409     if (s->current_frame.data[0])
 410         avctx->release_buffer(avctx, &s->current_frame);
 411
 412     av_free(s->buffer1);
 413     av_free(s->buffer2);
 414
 415     return 0;
 416 }
 417
 418 AVCodec xan_wc3_decoder = {
 419     "xan_wc3",
 420     CODEC_TYPE_VIDEO,
 421     CODEC_ID_XAN_WC3,
 422     sizeof(XanContext),
 423     xan_decode_init,
 424     NULL,
 425     xan_decode_end,
 426     xan_decode_frame,
 427     CODEC_CAP_DR1,
 428     .long_name = NULL_IF_CONFIG_SMALL("Wing Commander III / Xan"),
 429 };
 430
 431 /*
 432 AVCodec xan_wc4_decoder = {
 433     "xan_wc4",
 434     CODEC_TYPE_VIDEO,
 435     CODEC_ID_XAN_WC4,
 436     sizeof(XanContext),
 437     xan_decode_init,
 438     NULL,
 439     xan_decode_end,
 440     xan_decode_frame,
 441     CODEC_CAP_DR1,
 442 };
 443 */