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
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15 * Lesser General Public License for more details.
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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.
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 if(avcodec_check_dimensions(avctx, avctx->width, avctx->height))
80 s->buffer1_size = avctx->width * avctx->height;
81 s->buffer1 = av_malloc(s->buffer1_size);
82 s->buffer2_size = avctx->width * avctx->height;
83 s->buffer2 = av_malloc(s->buffer2_size + 130);
84 if (!s->buffer1 || !s->buffer2)
90 static int xan_huffman_decode(unsigned char *dest, const unsigned char *src,
93 unsigned char byte = *src++;
94 unsigned char ival = byte + 0x16;
95 const unsigned char * ptr = src + byte*2;
96 unsigned char val = ival;
97 unsigned char *dest_end = dest + dest_len;
100 init_get_bits(&gb, ptr, 0); // FIXME: no src size available
102 while ( val != 0x16 ) {
103 val = src[val - 0x17 + get_bits1(&gb) * byte];
106 if (dest >= dest_end)
117 * unpack simple compression
119 * @param dest destination buffer of dest_len, must be padded with at least 130 bytes
121 static void xan_unpack(unsigned char *dest, const unsigned char *src, int dest_len)
123 unsigned char opcode;
125 unsigned char *dest_end = dest + dest_len;
127 while (dest < dest_end) {
132 if ( (opcode & 0x80) == 0 ) {
136 back = ((opcode & 0x60) << 3) + *src++ + 1;
137 size2 = ((opcode & 0x1c) >> 2) + 3;
139 } else if ( (opcode & 0x40) == 0 ) {
143 back = (bytestream_get_be16(&src) & 0x3fff) + 1;
144 size2 = (opcode & 0x3f) + 4;
150 back = ((opcode & 0x10) << 12) + bytestream_get_be16(&src) + 1;
151 size2 = ((opcode & 0x0c) << 6) + *src++ + 5;
152 if (size + size2 > dest_end - dest)
155 memcpy(dest, src, size); dest += size; src += size;
156 av_memcpy_backptr(dest, back, size2);
159 int finish = opcode >= 0xfc;
160 size = finish ? opcode & 3 : ((opcode & 0x1f) << 2) + 4;
162 memcpy(dest, src, size); dest += size; src += size;
169 static inline void xan_wc3_output_pixel_run(XanContext *s,
170 const unsigned char *pixel_buffer, int x, int y, int pixel_count)
176 int width = s->avctx->width;
177 unsigned char *palette_plane;
179 palette_plane = s->current_frame.data[0];
180 stride = s->current_frame.linesize[0];
181 line_inc = stride - width;
182 index = y * stride + x;
184 while(pixel_count && (index < s->frame_size)) {
185 int count = FFMIN(pixel_count, width - current_x);
186 memcpy(palette_plane + index, pixel_buffer, count);
187 pixel_count -= count;
189 pixel_buffer += count;
192 if (current_x >= width) {
199 static inline void xan_wc3_copy_pixel_run(XanContext *s,
200 int x, int y, int pixel_count, int motion_x, int motion_y)
204 int curframe_index, prevframe_index;
205 int curframe_x, prevframe_x;
206 int width = s->avctx->width;
207 unsigned char *palette_plane, *prev_palette_plane;
209 palette_plane = s->current_frame.data[0];
210 prev_palette_plane = s->last_frame.data[0];
211 stride = s->current_frame.linesize[0];
212 line_inc = stride - width;
213 curframe_index = y * stride + x;
215 prevframe_index = (y + motion_y) * stride + x + motion_x;
216 prevframe_x = x + motion_x;
217 while(pixel_count && (curframe_index < s->frame_size)) {
218 int count = FFMIN3(pixel_count, width - curframe_x, width - prevframe_x);
220 memcpy(palette_plane + curframe_index, prev_palette_plane + prevframe_index, count);
221 pixel_count -= count;
222 curframe_index += count;
223 prevframe_index += count;
225 prevframe_x += count;
227 if (curframe_x >= width) {
228 curframe_index += line_inc;
232 if (prevframe_x >= width) {
233 prevframe_index += line_inc;
239 static void xan_wc3_decode_frame(XanContext *s) {
241 int width = s->avctx->width;
242 int height = s->avctx->height;
243 int total_pixels = width * height;
244 unsigned char opcode;
245 unsigned char flag = 0;
247 int motion_x, motion_y;
250 unsigned char *opcode_buffer = s->buffer1;
251 int opcode_buffer_size = s->buffer1_size;
252 const unsigned char *imagedata_buffer = s->buffer2;
254 /* pointers to segments inside the compressed chunk */
255 const unsigned char *huffman_segment;
256 const unsigned char *size_segment;
257 const unsigned char *vector_segment;
258 const unsigned char *imagedata_segment;
260 huffman_segment = s->buf + AV_RL16(&s->buf[0]);
261 size_segment = s->buf + AV_RL16(&s->buf[2]);
262 vector_segment = s->buf + AV_RL16(&s->buf[4]);
263 imagedata_segment = s->buf + AV_RL16(&s->buf[6]);
265 xan_huffman_decode(opcode_buffer, huffman_segment, opcode_buffer_size);
267 if (imagedata_segment[0] == 2)
268 xan_unpack(s->buffer2, &imagedata_segment[1], s->buffer2_size);
270 imagedata_buffer = &imagedata_segment[1];
272 /* use the decoded data segments to build the frame */
274 while (total_pixels) {
276 opcode = *opcode_buffer++;
303 size += (opcode - 10);
308 size = *size_segment++;
313 size = AV_RB16(&size_segment[0]);
319 size = AV_RB24(size_segment);
327 /* run of (size) pixels is unchanged from last frame */
328 xan_wc3_copy_pixel_run(s, x, y, size, 0, 0);
330 /* output a run of pixels from imagedata_buffer */
331 xan_wc3_output_pixel_run(s, imagedata_buffer, x, y, size);
332 imagedata_buffer += size;
335 /* run-based motion compensation from last frame */
336 motion_x = sign_extend(*vector_segment >> 4, 4);
337 motion_y = sign_extend(*vector_segment & 0xF, 4);
340 /* copy a run of pixels from the previous frame */
341 xan_wc3_copy_pixel_run(s, x, y, size, motion_x, motion_y);
346 /* coordinate accounting */
347 total_pixels -= size;
348 y += (x + size) / width;
349 x = (x + size) % width;
353 static void xan_wc4_decode_frame(XanContext *s) {
356 static int xan_decode_frame(AVCodecContext *avctx,
357 void *data, int *data_size,
360 const uint8_t *buf = avpkt->data;
361 int buf_size = avpkt->size;
362 XanContext *s = avctx->priv_data;
363 AVPaletteControl *palette_control = avctx->palctrl;
365 if (avctx->get_buffer(avctx, &s->current_frame)) {
366 av_log(s->avctx, AV_LOG_ERROR, " Xan Video: get_buffer() failed\n");
369 s->current_frame.reference = 3;
372 s->frame_size = s->current_frame.linesize[0] * s->avctx->height;
374 palette_control->palette_changed = 0;
375 memcpy(s->current_frame.data[1], palette_control->palette,
377 s->current_frame.palette_has_changed = 1;
382 if (avctx->codec->id == CODEC_ID_XAN_WC3)
383 xan_wc3_decode_frame(s);
384 else if (avctx->codec->id == CODEC_ID_XAN_WC4)
385 xan_wc4_decode_frame(s);
387 /* release the last frame if it is allocated */
388 if (s->last_frame.data[0])
389 avctx->release_buffer(avctx, &s->last_frame);
391 *data_size = sizeof(AVFrame);
392 *(AVFrame*)data = s->current_frame;
395 FFSWAP(AVFrame, s->current_frame, s->last_frame);
397 /* always report that the buffer was completely consumed */
401 static av_cold int xan_decode_end(AVCodecContext *avctx)
403 XanContext *s = avctx->priv_data;
405 /* release the frames */
406 if (s->last_frame.data[0])
407 avctx->release_buffer(avctx, &s->last_frame);
408 if (s->current_frame.data[0])
409 avctx->release_buffer(avctx, &s->current_frame);
417 AVCodec xan_wc3_decoder = {
427 .long_name = NULL_IF_CONFIG_SMALL("Wing Commander III / Xan"),
431 AVCodec xan_wc4_decoder = {