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
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)
28 * The xan_wc3 decoder outputs PAL8 data.
36 #include "libavutil/intreadwrite.h"
38 #include "bytestream.h"
39 // for av_memcpy_backptr
40 #include "libavutil/lzo.h"
42 typedef struct XanContext {
44 AVCodecContext *avctx;
46 AVFrame current_frame;
48 const unsigned char *buf;
52 unsigned char *buffer1;
54 unsigned char *buffer2;
61 static av_cold int xan_decode_init(AVCodecContext *avctx)
63 XanContext *s = avctx->priv_data;
68 if ((avctx->codec->id == CODEC_ID_XAN_WC3) &&
69 (s->avctx->palctrl == NULL)) {
70 av_log(avctx, AV_LOG_ERROR, " WC3 Xan video: palette expected.\n");
74 avctx->pix_fmt = PIX_FMT_PAL8;
76 if(avcodec_check_dimensions(avctx, avctx->width, avctx->height))
79 s->buffer1_size = avctx->width * avctx->height;
80 s->buffer1 = av_malloc(s->buffer1_size);
81 s->buffer2_size = avctx->width * avctx->height;
82 s->buffer2 = av_malloc(s->buffer2_size + 130);
83 if (!s->buffer1 || !s->buffer2)
89 static int xan_huffman_decode(unsigned char *dest, const unsigned char *src,
92 unsigned char byte = *src++;
93 unsigned char ival = byte + 0x16;
94 const unsigned char * ptr = src + byte*2;
95 unsigned char val = ival;
97 unsigned char *dest_end = dest + dest_len;
99 unsigned char bits = *ptr++;
101 while ( val != 0x16 ) {
102 if ( (1 << counter) & bits )
103 val = src[byte + val - 0x17];
105 val = src[val - 0x17];
108 if (dest + 1 > dest_end)
114 if (counter++ == 7) {
124 * unpack simple compression
126 * @param dest destination buffer of dest_len, must be padded with at least 130 bytes
128 static void xan_unpack(unsigned char *dest, const unsigned char *src, int dest_len)
130 unsigned char opcode;
132 unsigned char *dest_end = dest + dest_len;
134 while (dest < dest_end) {
139 if ( (opcode & 0x80) == 0 ) {
143 size2 = ((opcode & 0x1c) >> 2) + 3;
144 back = ((opcode & 0x60) << 3) + *src++ + 1;
146 } else if ( (opcode & 0x40) == 0 ) {
150 size2 = (opcode & 0x3f) + 4;
151 back = (bytestream_get_be16(&src) & 0x3fff) + 1;
157 back = ((opcode & 0x10) << 12) + 1 + bytestream_get_be16(&src);
158 size2 = *src++ + 5 + ((opcode & 0xc) << 6);
159 if (size + size2 > dest_end - dest)
162 memcpy(dest, src, size); dest += size; src += size;
163 av_memcpy_backptr(dest, back, size2);
166 size = ((opcode & 0x1f) << 2) + 4;
171 memcpy(dest, src, size); dest += size; src += size;
176 memcpy(dest, src, size); dest += size; src += size;
179 static inline void xan_wc3_output_pixel_run(XanContext *s,
180 const unsigned char *pixel_buffer, int x, int y, int pixel_count)
186 int width = s->avctx->width;
187 unsigned char *palette_plane;
189 palette_plane = s->current_frame.data[0];
190 stride = s->current_frame.linesize[0];
191 line_inc = stride - width;
192 index = y * stride + x;
194 while((pixel_count--) && (index < s->frame_size)) {
196 /* don't do a memcpy() here; keyframes generally copy an entire
197 * frame of data and the stride needs to be accounted for */
198 palette_plane[index++] = *pixel_buffer++;
201 if (current_x >= width) {
208 static inline void xan_wc3_copy_pixel_run(XanContext *s,
209 int x, int y, int pixel_count, int motion_x, int motion_y)
213 int curframe_index, prevframe_index;
214 int curframe_x, prevframe_x;
215 int width = s->avctx->width;
216 unsigned char *palette_plane, *prev_palette_plane;
218 palette_plane = s->current_frame.data[0];
219 prev_palette_plane = s->last_frame.data[0];
220 stride = s->current_frame.linesize[0];
221 line_inc = stride - width;
222 curframe_index = y * stride + x;
224 prevframe_index = (y + motion_y) * stride + x + motion_x;
225 prevframe_x = x + motion_x;
226 while((pixel_count--) && (curframe_index < s->frame_size)) {
228 palette_plane[curframe_index++] =
229 prev_palette_plane[prevframe_index++];
232 if (curframe_x >= width) {
233 curframe_index += line_inc;
238 if (prevframe_x >= width) {
239 prevframe_index += line_inc;
245 static void xan_wc3_decode_frame(XanContext *s) {
247 int width = s->avctx->width;
248 int height = s->avctx->height;
249 int total_pixels = width * height;
250 unsigned char opcode;
251 unsigned char flag = 0;
253 int motion_x, motion_y;
256 unsigned char *opcode_buffer = s->buffer1;
257 int opcode_buffer_size = s->buffer1_size;
258 const unsigned char *imagedata_buffer = s->buffer2;
260 /* pointers to segments inside the compressed chunk */
261 const unsigned char *huffman_segment;
262 const unsigned char *size_segment;
263 const unsigned char *vector_segment;
264 const unsigned char *imagedata_segment;
266 huffman_segment = s->buf + AV_RL16(&s->buf[0]);
267 size_segment = s->buf + AV_RL16(&s->buf[2]);
268 vector_segment = s->buf + AV_RL16(&s->buf[4]);
269 imagedata_segment = s->buf + AV_RL16(&s->buf[6]);
271 xan_huffman_decode(opcode_buffer, huffman_segment, opcode_buffer_size);
273 if (imagedata_segment[0] == 2)
274 xan_unpack(s->buffer2, &imagedata_segment[1], s->buffer2_size);
276 imagedata_buffer = &imagedata_segment[1];
278 /* use the decoded data segments to build the frame */
280 while (total_pixels) {
282 opcode = *opcode_buffer++;
309 size += (opcode - 10);
314 size = *size_segment++;
319 size = AV_RB16(&size_segment[0]);
325 size = AV_RB24(size_segment);
333 /* run of (size) pixels is unchanged from last frame */
334 xan_wc3_copy_pixel_run(s, x, y, size, 0, 0);
336 /* output a run of pixels from imagedata_buffer */
337 xan_wc3_output_pixel_run(s, imagedata_buffer, x, y, size);
338 imagedata_buffer += size;
341 /* run-based motion compensation from last frame */
342 motion_x = (*vector_segment >> 4) & 0xF;
343 motion_y = *vector_segment & 0xF;
348 motion_x |= 0xFFFFFFF0;
350 motion_y |= 0xFFFFFFF0;
352 /* copy a run of pixels from the previous frame */
353 xan_wc3_copy_pixel_run(s, x, y, size, motion_x, motion_y);
358 /* coordinate accounting */
359 total_pixels -= size;
361 if (x + size >= width) {
373 static void xan_wc4_decode_frame(XanContext *s) {
376 static int xan_decode_frame(AVCodecContext *avctx,
377 void *data, int *data_size,
380 const uint8_t *buf = avpkt->data;
381 int buf_size = avpkt->size;
382 XanContext *s = avctx->priv_data;
383 AVPaletteControl *palette_control = avctx->palctrl;
385 if (avctx->get_buffer(avctx, &s->current_frame)) {
386 av_log(s->avctx, AV_LOG_ERROR, " Xan Video: get_buffer() failed\n");
389 s->current_frame.reference = 3;
392 s->frame_size = s->current_frame.linesize[0] * s->avctx->height;
394 palette_control->palette_changed = 0;
395 memcpy(s->current_frame.data[1], palette_control->palette,
397 s->current_frame.palette_has_changed = 1;
402 if (avctx->codec->id == CODEC_ID_XAN_WC3)
403 xan_wc3_decode_frame(s);
404 else if (avctx->codec->id == CODEC_ID_XAN_WC4)
405 xan_wc4_decode_frame(s);
407 /* release the last frame if it is allocated */
408 if (s->last_frame.data[0])
409 avctx->release_buffer(avctx, &s->last_frame);
411 *data_size = sizeof(AVFrame);
412 *(AVFrame*)data = s->current_frame;
415 FFSWAP(AVFrame, s->current_frame, s->last_frame);
417 /* always report that the buffer was completely consumed */
421 static av_cold int xan_decode_end(AVCodecContext *avctx)
423 XanContext *s = avctx->priv_data;
425 /* release the frames */
426 if (s->last_frame.data[0])
427 avctx->release_buffer(avctx, &s->last_frame);
428 if (s->current_frame.data[0])
429 avctx->release_buffer(avctx, &s->current_frame);
437 AVCodec xan_wc3_decoder = {
447 .long_name = NULL_IF_CONFIG_SMALL("Wing Commander III / Xan"),
451 AVCodec xan_wc4_decoder = {