2 * Wing Commander/Xan Video Decoder
3 * Copyright (C) 2003 the ffmpeg project
5 * This file is part of FFmpeg.
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.
12 * FFmpeg is distributed in the hope that it will be useful,
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14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
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
25 * Xan video decoder for Wing Commander III computer game
26 * by Mario Brito (mbrito@student.dei.uc.pt)
27 * and Mike Melanson (melanson@pcisys.net)
29 * The xan_wc3 decoder outputs PAL8 data.
40 typedef struct XanContext {
42 AVCodecContext *avctx;
44 AVFrame current_frame;
50 unsigned char *buffer1;
52 unsigned char *buffer2;
59 static int xan_decode_init(AVCodecContext *avctx)
61 XanContext *s = avctx->priv_data;
66 if ((avctx->codec->id == CODEC_ID_XAN_WC3) &&
67 (s->avctx->palctrl == NULL)) {
68 av_log(avctx, AV_LOG_ERROR, " WC3 Xan video: palette expected.\n");
72 avctx->pix_fmt = PIX_FMT_PAL8;
73 avctx->has_b_frames = 0;
75 if(avcodec_check_dimensions(avctx, avctx->width, avctx->height))
78 s->buffer1_size = avctx->width * avctx->height;
79 s->buffer1 = av_malloc(s->buffer1_size);
80 s->buffer2_size = avctx->width * avctx->height;
81 s->buffer2 = av_malloc(s->buffer2_size);
82 if (!s->buffer1 || !s->buffer2)
88 /* This function is used in lieu of memcpy(). This decoder can not use
89 * memcpy because the memory locations often overlap and
90 * memcpy doesn't like that; it's not uncommon, for example, for
91 * dest = src+1, to turn byte A into pattern AAAAAAAA.
92 * This was originally repz movsb in Intel x86 ASM. */
93 static inline void bytecopy(unsigned char *dest, unsigned char *src, int count)
97 for (i = 0; i < count; i++)
101 static int xan_huffman_decode(unsigned char *dest, unsigned char *src,
104 unsigned char byte = *src++;
105 unsigned char ival = byte + 0x16;
106 unsigned char * ptr = src + byte*2;
107 unsigned char val = ival;
109 unsigned char *dest_end = dest + dest_len;
111 unsigned char bits = *ptr++;
113 while ( val != 0x16 ) {
114 if ( (1 << counter) & bits )
115 val = src[byte + val - 0x17];
117 val = src[val - 0x17];
120 if (dest + 1 > dest_end)
126 if (counter++ == 7) {
135 static void xan_unpack(unsigned char *dest, unsigned char *src, int dest_len)
137 unsigned char opcode;
140 int byte1, byte2, byte3;
141 unsigned char *dest_end = dest + dest_len;
146 if ( (opcode & 0x80) == 0 ) {
151 if (dest + size > dest_end)
153 bytecopy(dest, src, size); dest += size; src += size;
155 size = ((opcode & 0x1c) >> 2) + 3;
156 if (dest + size > dest_end)
158 bytecopy (dest, dest - (((opcode & 0x60) << 3) + offset + 1), size);
161 } else if ( (opcode & 0x40) == 0 ) {
167 if (dest + size > dest_end)
169 bytecopy (dest, src, size); dest += size; src += size;
171 size = (opcode & 0x3f) + 4;
172 if (dest + size > dest_end)
174 bytecopy (dest, dest - (((byte1 & 0x3f) << 8) + byte2 + 1), size);
177 } else if ( (opcode & 0x20) == 0 ) {
184 if (dest + size > dest_end)
186 bytecopy (dest, src, size); dest += size; src += size;
188 size = byte3 + 5 + ((opcode & 0xc) << 6);
189 if (dest + size > dest_end)
192 dest - ((((opcode & 0x10) >> 4) << 0x10) + 1 + (byte1 << 8) + byte2),
196 size = ((opcode & 0x1f) << 2) + 4;
201 if (dest + size > dest_end)
203 bytecopy (dest, src, size); dest += size; src += size;
208 bytecopy(dest, src, size); dest += size; src += size;
211 static void inline xan_wc3_output_pixel_run(XanContext *s,
212 unsigned char *pixel_buffer, int x, int y, int pixel_count)
218 int width = s->avctx->width;
219 unsigned char *palette_plane;
221 palette_plane = s->current_frame.data[0];
222 stride = s->current_frame.linesize[0];
223 line_inc = stride - width;
224 index = y * stride + x;
226 while((pixel_count--) && (index < s->frame_size)) {
228 /* don't do a memcpy() here; keyframes generally copy an entire
229 * frame of data and the stride needs to be accounted for */
230 palette_plane[index++] = *pixel_buffer++;
233 if (current_x >= width) {
240 static void inline xan_wc3_copy_pixel_run(XanContext *s,
241 int x, int y, int pixel_count, int motion_x, int motion_y)
245 int curframe_index, prevframe_index;
246 int curframe_x, prevframe_x;
247 int width = s->avctx->width;
248 unsigned char *palette_plane, *prev_palette_plane;
250 palette_plane = s->current_frame.data[0];
251 prev_palette_plane = s->last_frame.data[0];
252 stride = s->current_frame.linesize[0];
253 line_inc = stride - width;
254 curframe_index = y * stride + x;
256 prevframe_index = (y + motion_y) * stride + x + motion_x;
257 prevframe_x = x + motion_x;
258 while((pixel_count--) && (curframe_index < s->frame_size)) {
260 palette_plane[curframe_index++] =
261 prev_palette_plane[prevframe_index++];
264 if (curframe_x >= width) {
265 curframe_index += line_inc;
270 if (prevframe_x >= width) {
271 prevframe_index += line_inc;
277 static void xan_wc3_decode_frame(XanContext *s) {
279 int width = s->avctx->width;
280 int height = s->avctx->height;
281 int total_pixels = width * height;
282 unsigned char opcode;
283 unsigned char flag = 0;
285 int motion_x, motion_y;
288 unsigned char *opcode_buffer = s->buffer1;
289 int opcode_buffer_size = s->buffer1_size;
290 unsigned char *imagedata_buffer = s->buffer2;
291 int imagedata_buffer_size = s->buffer2_size;
293 /* pointers to segments inside the compressed chunk */
294 unsigned char *huffman_segment;
295 unsigned char *size_segment;
296 unsigned char *vector_segment;
297 unsigned char *imagedata_segment;
299 huffman_segment = s->buf + AV_RL16(&s->buf[0]);
300 size_segment = s->buf + AV_RL16(&s->buf[2]);
301 vector_segment = s->buf + AV_RL16(&s->buf[4]);
302 imagedata_segment = s->buf + AV_RL16(&s->buf[6]);
304 xan_huffman_decode(opcode_buffer, huffman_segment, opcode_buffer_size);
306 if (imagedata_segment[0] == 2)
307 xan_unpack(imagedata_buffer, &imagedata_segment[1],
308 imagedata_buffer_size);
310 imagedata_buffer = &imagedata_segment[1];
312 /* use the decoded data segments to build the frame */
314 while (total_pixels) {
316 opcode = *opcode_buffer++;
343 size += (opcode - 10);
348 size = *size_segment++;
353 size = AV_RB16(&size_segment[0]);
359 size = (size_segment[0] << 16) | (size_segment[1] << 8) |
368 /* run of (size) pixels is unchanged from last frame */
369 xan_wc3_copy_pixel_run(s, x, y, size, 0, 0);
371 /* output a run of pixels from imagedata_buffer */
372 xan_wc3_output_pixel_run(s, imagedata_buffer, x, y, size);
373 imagedata_buffer += size;
376 /* run-based motion compensation from last frame */
377 motion_x = (*vector_segment >> 4) & 0xF;
378 motion_y = *vector_segment & 0xF;
383 motion_x |= 0xFFFFFFF0;
385 motion_y |= 0xFFFFFFF0;
387 /* copy a run of pixels from the previous frame */
388 xan_wc3_copy_pixel_run(s, x, y, size, motion_x, motion_y);
393 /* coordinate accounting */
394 total_pixels -= size;
396 if (x + size >= width) {
408 static void xan_wc4_decode_frame(XanContext *s) {
411 static int xan_decode_frame(AVCodecContext *avctx,
412 void *data, int *data_size,
413 uint8_t *buf, int buf_size)
415 XanContext *s = avctx->priv_data;
416 AVPaletteControl *palette_control = avctx->palctrl;
418 if (avctx->get_buffer(avctx, &s->current_frame)) {
419 av_log(s->avctx, AV_LOG_ERROR, " Xan Video: get_buffer() failed\n");
422 s->current_frame.reference = 3;
425 s->frame_size = s->current_frame.linesize[0] * s->avctx->height;
427 palette_control->palette_changed = 0;
428 memcpy(s->current_frame.data[1], palette_control->palette,
430 s->current_frame.palette_has_changed = 1;
435 if (avctx->codec->id == CODEC_ID_XAN_WC3)
436 xan_wc3_decode_frame(s);
437 else if (avctx->codec->id == CODEC_ID_XAN_WC4)
438 xan_wc4_decode_frame(s);
440 /* release the last frame if it is allocated */
441 if (s->last_frame.data[0])
442 avctx->release_buffer(avctx, &s->last_frame);
445 s->last_frame = s->current_frame;
447 *data_size = sizeof(AVFrame);
448 *(AVFrame*)data = s->current_frame;
450 /* always report that the buffer was completely consumed */
454 static int xan_decode_end(AVCodecContext *avctx)
456 XanContext *s = avctx->priv_data;
458 /* release the last frame */
459 if (s->last_frame.data[0])
460 avctx->release_buffer(avctx, &s->last_frame);
468 AVCodec xan_wc3_decoder = {
481 AVCodec xan_wc4_decoder = {