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.
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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
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)
28 * The xan_wc3 decoder outputs PAL8 data.
35 #include "libavutil/intreadwrite.h"
37 #include "bytestream.h"
38 #define ALT_BITSTREAM_READER_LE
40 // for av_memcpy_backptr
41 #include "libavutil/lzo.h"
43 typedef struct XanContext {
45 AVCodecContext *avctx;
47 AVFrame current_frame;
49 const unsigned char *buf;
53 unsigned char *buffer1;
55 unsigned char *buffer2;
62 static av_cold int xan_decode_init(AVCodecContext *avctx)
64 XanContext *s = avctx->priv_data;
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");
75 avctx->pix_fmt = PIX_FMT_PAL8;
77 s->buffer1_size = avctx->width * avctx->height;
78 s->buffer1 = av_malloc(s->buffer1_size);
81 s->buffer2_size = avctx->width * avctx->height;
82 s->buffer2 = av_malloc(s->buffer2_size + 130);
84 av_freep(&s->buffer1);
91 static int xan_huffman_decode(unsigned char *dest, const unsigned char *src,
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;
101 init_get_bits(&gb, ptr, 0); // FIXME: no src size available
103 while ( val != 0x16 ) {
104 val = src[val - 0x17 + get_bits1(&gb) * byte];
107 if (dest >= dest_end)
118 * unpack simple compression
120 * @param dest destination buffer of dest_len, must be padded with at least 130 bytes
122 static void xan_unpack(unsigned char *dest, const unsigned char *src, int dest_len)
124 unsigned char opcode;
126 unsigned char *dest_end = dest + dest_len;
128 while (dest < dest_end) {
133 if ( (opcode & 0x80) == 0 ) {
137 back = ((opcode & 0x60) << 3) + *src++ + 1;
138 size2 = ((opcode & 0x1c) >> 2) + 3;
140 } else if ( (opcode & 0x40) == 0 ) {
144 back = (bytestream_get_be16(&src) & 0x3fff) + 1;
145 size2 = (opcode & 0x3f) + 4;
151 back = ((opcode & 0x10) << 12) + bytestream_get_be16(&src) + 1;
152 size2 = ((opcode & 0x0c) << 6) + *src++ + 5;
153 if (size + size2 > dest_end - dest)
156 memcpy(dest, src, size); dest += size; src += size;
157 av_memcpy_backptr(dest, back, size2);
160 int finish = opcode >= 0xfc;
161 size = finish ? opcode & 3 : ((opcode & 0x1f) << 2) + 4;
163 memcpy(dest, src, size); dest += size; src += size;
170 static inline void xan_wc3_output_pixel_run(XanContext *s,
171 const unsigned char *pixel_buffer, int x, int y, int pixel_count)
177 int width = s->avctx->width;
178 unsigned char *palette_plane;
180 palette_plane = s->current_frame.data[0];
181 stride = s->current_frame.linesize[0];
182 line_inc = stride - width;
183 index = y * stride + x;
185 while(pixel_count && (index < s->frame_size)) {
186 int count = FFMIN(pixel_count, width - current_x);
187 memcpy(palette_plane + index, pixel_buffer, count);
188 pixel_count -= count;
190 pixel_buffer += count;
193 if (current_x >= width) {
200 static inline void xan_wc3_copy_pixel_run(XanContext *s,
201 int x, int y, int pixel_count, int motion_x, int motion_y)
205 int curframe_index, prevframe_index;
206 int curframe_x, prevframe_x;
207 int width = s->avctx->width;
208 unsigned char *palette_plane, *prev_palette_plane;
210 palette_plane = s->current_frame.data[0];
211 prev_palette_plane = s->last_frame.data[0];
212 stride = s->current_frame.linesize[0];
213 line_inc = stride - width;
214 curframe_index = y * stride + x;
216 prevframe_index = (y + motion_y) * stride + x + motion_x;
217 prevframe_x = x + motion_x;
218 while(pixel_count && (curframe_index < s->frame_size)) {
219 int count = FFMIN3(pixel_count, width - curframe_x, width - prevframe_x);
221 memcpy(palette_plane + curframe_index, prev_palette_plane + prevframe_index, count);
222 pixel_count -= count;
223 curframe_index += count;
224 prevframe_index += count;
226 prevframe_x += count;
228 if (curframe_x >= width) {
229 curframe_index += line_inc;
233 if (prevframe_x >= width) {
234 prevframe_index += line_inc;
240 static void xan_wc3_decode_frame(XanContext *s) {
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;
248 int motion_x, motion_y;
251 unsigned char *opcode_buffer = s->buffer1;
252 int opcode_buffer_size = s->buffer1_size;
253 const unsigned char *imagedata_buffer = s->buffer2;
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;
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]);
266 xan_huffman_decode(opcode_buffer, huffman_segment, opcode_buffer_size);
268 if (imagedata_segment[0] == 2)
269 xan_unpack(s->buffer2, &imagedata_segment[1], s->buffer2_size);
271 imagedata_buffer = &imagedata_segment[1];
273 /* use the decoded data segments to build the frame */
275 while (total_pixels) {
277 opcode = *opcode_buffer++;
304 size += (opcode - 10);
309 size = *size_segment++;
314 size = AV_RB16(&size_segment[0]);
320 size = AV_RB24(size_segment);
328 /* run of (size) pixels is unchanged from last frame */
329 xan_wc3_copy_pixel_run(s, x, y, size, 0, 0);
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;
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);
341 /* copy a run of pixels from the previous frame */
342 xan_wc3_copy_pixel_run(s, x, y, size, motion_x, motion_y);
347 /* coordinate accounting */
348 total_pixels -= size;
349 y += (x + size) / width;
350 x = (x + size) % width;
354 static void xan_wc4_decode_frame(XanContext *s) {
357 static int xan_decode_frame(AVCodecContext *avctx,
358 void *data, int *data_size,
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;
366 if (avctx->get_buffer(avctx, &s->current_frame)) {
367 av_log(s->avctx, AV_LOG_ERROR, " Xan Video: get_buffer() failed\n");
370 s->current_frame.reference = 3;
373 s->frame_size = s->current_frame.linesize[0] * s->avctx->height;
375 palette_control->palette_changed = 0;
376 memcpy(s->current_frame.data[1], palette_control->palette,
378 s->current_frame.palette_has_changed = 1;
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);
388 /* release the last frame if it is allocated */
389 if (s->last_frame.data[0])
390 avctx->release_buffer(avctx, &s->last_frame);
392 *data_size = sizeof(AVFrame);
393 *(AVFrame*)data = s->current_frame;
396 FFSWAP(AVFrame, s->current_frame, s->last_frame);
398 /* always report that the buffer was completely consumed */
402 static av_cold int xan_decode_end(AVCodecContext *avctx)
404 XanContext *s = avctx->priv_data;
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);
412 av_freep(&s->buffer1);
413 av_freep(&s->buffer2);
418 AVCodec xan_wc3_decoder = {
428 .long_name = NULL_IF_CONFIG_SMALL("Wing Commander III / Xan"),
432 AVCodec xan_wc4_decoder = {
442 .long_name = NULL_IF_CONFIG_SMALL("Wing Commander IV / Xxan"),