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;
74 if(avcodec_check_dimensions(avctx, avctx->width, avctx->height))
77 s->buffer1_size = avctx->width * avctx->height;
78 s->buffer1 = av_malloc(s->buffer1_size);
79 s->buffer2_size = avctx->width * avctx->height;
80 s->buffer2 = av_malloc(s->buffer2_size);
81 if (!s->buffer1 || !s->buffer2)
87 /* This function is used in lieu of memcpy(). This decoder cannot use
88 * memcpy because the memory locations often overlap and
89 * memcpy doesn't like that; it's not uncommon, for example, for
90 * dest = src+1, to turn byte A into pattern AAAAAAAA.
91 * This was originally repz movsb in Intel x86 ASM. */
92 static inline void bytecopy(unsigned char *dest, unsigned char *src, int count)
96 for (i = 0; i < count; i++)
100 static int xan_huffman_decode(unsigned char *dest, unsigned char *src,
103 unsigned char byte = *src++;
104 unsigned char ival = byte + 0x16;
105 unsigned char * ptr = src + byte*2;
106 unsigned char val = ival;
108 unsigned char *dest_end = dest + dest_len;
110 unsigned char bits = *ptr++;
112 while ( val != 0x16 ) {
113 if ( (1 << counter) & bits )
114 val = src[byte + val - 0x17];
116 val = src[val - 0x17];
119 if (dest + 1 > dest_end)
125 if (counter++ == 7) {
134 static void xan_unpack(unsigned char *dest, unsigned char *src, int dest_len)
136 unsigned char opcode;
139 int byte1, byte2, byte3;
140 unsigned char *dest_end = dest + dest_len;
145 if ( (opcode & 0x80) == 0 ) {
150 if (dest + size > dest_end)
152 bytecopy(dest, src, size); dest += size; src += size;
154 size = ((opcode & 0x1c) >> 2) + 3;
155 if (dest + size > dest_end)
157 bytecopy (dest, dest - (((opcode & 0x60) << 3) + offset + 1), size);
160 } else if ( (opcode & 0x40) == 0 ) {
166 if (dest + size > dest_end)
168 bytecopy (dest, src, size); dest += size; src += size;
170 size = (opcode & 0x3f) + 4;
171 if (dest + size > dest_end)
173 bytecopy (dest, dest - (((byte1 & 0x3f) << 8) + byte2 + 1), size);
176 } else if ( (opcode & 0x20) == 0 ) {
183 if (dest + size > dest_end)
185 bytecopy (dest, src, size); dest += size; src += size;
187 size = byte3 + 5 + ((opcode & 0xc) << 6);
188 if (dest + size > dest_end)
191 dest - ((((opcode & 0x10) >> 4) << 0x10) + 1 + (byte1 << 8) + byte2),
195 size = ((opcode & 0x1f) << 2) + 4;
200 if (dest + size > dest_end)
202 bytecopy (dest, src, size); dest += size; src += size;
207 bytecopy(dest, src, size); dest += size; src += size;
210 static inline void xan_wc3_output_pixel_run(XanContext *s,
211 unsigned char *pixel_buffer, int x, int y, int pixel_count)
217 int width = s->avctx->width;
218 unsigned char *palette_plane;
220 palette_plane = s->current_frame.data[0];
221 stride = s->current_frame.linesize[0];
222 line_inc = stride - width;
223 index = y * stride + x;
225 while((pixel_count--) && (index < s->frame_size)) {
227 /* don't do a memcpy() here; keyframes generally copy an entire
228 * frame of data and the stride needs to be accounted for */
229 palette_plane[index++] = *pixel_buffer++;
232 if (current_x >= width) {
239 static inline void xan_wc3_copy_pixel_run(XanContext *s,
240 int x, int y, int pixel_count, int motion_x, int motion_y)
244 int curframe_index, prevframe_index;
245 int curframe_x, prevframe_x;
246 int width = s->avctx->width;
247 unsigned char *palette_plane, *prev_palette_plane;
249 palette_plane = s->current_frame.data[0];
250 prev_palette_plane = s->last_frame.data[0];
251 stride = s->current_frame.linesize[0];
252 line_inc = stride - width;
253 curframe_index = y * stride + x;
255 prevframe_index = (y + motion_y) * stride + x + motion_x;
256 prevframe_x = x + motion_x;
257 while((pixel_count--) && (curframe_index < s->frame_size)) {
259 palette_plane[curframe_index++] =
260 prev_palette_plane[prevframe_index++];
263 if (curframe_x >= width) {
264 curframe_index += line_inc;
269 if (prevframe_x >= width) {
270 prevframe_index += line_inc;
276 static void xan_wc3_decode_frame(XanContext *s) {
278 int width = s->avctx->width;
279 int height = s->avctx->height;
280 int total_pixels = width * height;
281 unsigned char opcode;
282 unsigned char flag = 0;
284 int motion_x, motion_y;
287 unsigned char *opcode_buffer = s->buffer1;
288 int opcode_buffer_size = s->buffer1_size;
289 unsigned char *imagedata_buffer = s->buffer2;
290 int imagedata_buffer_size = s->buffer2_size;
292 /* pointers to segments inside the compressed chunk */
293 unsigned char *huffman_segment;
294 unsigned char *size_segment;
295 unsigned char *vector_segment;
296 unsigned char *imagedata_segment;
298 huffman_segment = s->buf + AV_RL16(&s->buf[0]);
299 size_segment = s->buf + AV_RL16(&s->buf[2]);
300 vector_segment = s->buf + AV_RL16(&s->buf[4]);
301 imagedata_segment = s->buf + AV_RL16(&s->buf[6]);
303 xan_huffman_decode(opcode_buffer, huffman_segment, opcode_buffer_size);
305 if (imagedata_segment[0] == 2)
306 xan_unpack(imagedata_buffer, &imagedata_segment[1],
307 imagedata_buffer_size);
309 imagedata_buffer = &imagedata_segment[1];
311 /* use the decoded data segments to build the frame */
313 while (total_pixels) {
315 opcode = *opcode_buffer++;
342 size += (opcode - 10);
347 size = *size_segment++;
352 size = AV_RB16(&size_segment[0]);
358 size = (size_segment[0] << 16) | (size_segment[1] << 8) |
367 /* run of (size) pixels is unchanged from last frame */
368 xan_wc3_copy_pixel_run(s, x, y, size, 0, 0);
370 /* output a run of pixels from imagedata_buffer */
371 xan_wc3_output_pixel_run(s, imagedata_buffer, x, y, size);
372 imagedata_buffer += size;
375 /* run-based motion compensation from last frame */
376 motion_x = (*vector_segment >> 4) & 0xF;
377 motion_y = *vector_segment & 0xF;
382 motion_x |= 0xFFFFFFF0;
384 motion_y |= 0xFFFFFFF0;
386 /* copy a run of pixels from the previous frame */
387 xan_wc3_copy_pixel_run(s, x, y, size, motion_x, motion_y);
392 /* coordinate accounting */
393 total_pixels -= size;
395 if (x + size >= width) {
407 static void xan_wc4_decode_frame(XanContext *s) {
410 static int xan_decode_frame(AVCodecContext *avctx,
411 void *data, int *data_size,
412 uint8_t *buf, int buf_size)
414 XanContext *s = avctx->priv_data;
415 AVPaletteControl *palette_control = avctx->palctrl;
417 if (avctx->get_buffer(avctx, &s->current_frame)) {
418 av_log(s->avctx, AV_LOG_ERROR, " Xan Video: get_buffer() failed\n");
421 s->current_frame.reference = 3;
424 s->frame_size = s->current_frame.linesize[0] * s->avctx->height;
426 palette_control->palette_changed = 0;
427 memcpy(s->current_frame.data[1], palette_control->palette,
429 s->current_frame.palette_has_changed = 1;
434 if (avctx->codec->id == CODEC_ID_XAN_WC3)
435 xan_wc3_decode_frame(s);
436 else if (avctx->codec->id == CODEC_ID_XAN_WC4)
437 xan_wc4_decode_frame(s);
439 /* release the last frame if it is allocated */
440 if (s->last_frame.data[0])
441 avctx->release_buffer(avctx, &s->last_frame);
444 s->last_frame = s->current_frame;
446 *data_size = sizeof(AVFrame);
447 *(AVFrame*)data = s->current_frame;
449 /* always report that the buffer was completely consumed */
453 static int xan_decode_end(AVCodecContext *avctx)
455 XanContext *s = avctx->priv_data;
457 /* release the last frame */
458 if (s->last_frame.data[0])
459 avctx->release_buffer(avctx, &s->last_frame);
467 AVCodec xan_wc3_decoder = {
480 AVCodec xan_wc4_decoder = {