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cdgraphics.c
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1 /*
2  * CD Graphics Video Decoder
3  * Copyright (c) 2009 Michael Tison
4  *
5  * This file is part of FFmpeg.
6  *
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.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
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
20  */
21 
22 #include "avcodec.h"
23 #include "bytestream.h"
24 #include "internal.h"
25 
26 /**
27  * @file
28  * @brief CD Graphics Video Decoder
29  * @author Michael Tison
30  * @see http://wiki.multimedia.cx/index.php?title=CD_Graphics
31  * @see http://www.ccs.neu.edu/home/bchafy/cdb/info/cdg
32  */
33 
34 /// default screen sizes
35 #define CDG_FULL_WIDTH 300
36 #define CDG_FULL_HEIGHT 216
37 #define CDG_DISPLAY_WIDTH 294
38 #define CDG_DISPLAY_HEIGHT 204
39 #define CDG_BORDER_WIDTH 6
40 #define CDG_BORDER_HEIGHT 12
41 
42 /// masks
43 #define CDG_COMMAND 0x09
44 #define CDG_MASK 0x3F
45 
46 /// instruction codes
47 #define CDG_INST_MEMORY_PRESET 1
48 #define CDG_INST_BORDER_PRESET 2
49 #define CDG_INST_TILE_BLOCK 6
50 #define CDG_INST_SCROLL_PRESET 20
51 #define CDG_INST_SCROLL_COPY 24
52 #define CDG_INST_LOAD_PAL_LO 30
53 #define CDG_INST_LOAD_PAL_HIGH 31
54 #define CDG_INST_TILE_BLOCK_XOR 38
55 
56 /// data sizes
57 #define CDG_PACKET_SIZE 24
58 #define CDG_DATA_SIZE 16
59 #define CDG_TILE_HEIGHT 12
60 #define CDG_TILE_WIDTH 6
61 #define CDG_MINIMUM_PKT_SIZE 6
62 #define CDG_MINIMUM_SCROLL_SIZE 3
63 #define CDG_HEADER_SIZE 8
64 #define CDG_PALETTE_SIZE 16
65 
66 typedef struct CDGraphicsContext {
68  int hscroll;
69  int vscroll;
71 
73 {
74  CDGraphicsContext *cc = avctx->priv_data;
75 
76  cc->frame = av_frame_alloc();
77  if (!cc->frame)
78  return AVERROR(ENOMEM);
79 
80  avctx->width = CDG_FULL_WIDTH;
81  avctx->height = CDG_FULL_HEIGHT;
82  avctx->pix_fmt = AV_PIX_FMT_PAL8;
83 
84  return 0;
85 }
86 
88 {
89  int y;
90  int lsize = cc->frame->linesize[0];
91  uint8_t *buf = cc->frame->data[0];
92  int color = data[0] & 0x0F;
93 
94  if (!(data[1] & 0x0F)) {
95  /// fill the top and bottom borders
96  memset(buf, color, CDG_BORDER_HEIGHT * lsize);
97  memset(buf + (CDG_FULL_HEIGHT - CDG_BORDER_HEIGHT) * lsize,
98  color, CDG_BORDER_HEIGHT * lsize);
99 
100  /// fill the side borders
101  for (y = CDG_BORDER_HEIGHT; y < CDG_FULL_HEIGHT - CDG_BORDER_HEIGHT; y++) {
102  memset(buf + y * lsize, color, CDG_BORDER_WIDTH);
103  memset(buf + CDG_FULL_WIDTH - CDG_BORDER_WIDTH + y * lsize,
104  color, CDG_BORDER_WIDTH);
105  }
106  }
107 }
108 
109 static void cdg_load_palette(CDGraphicsContext *cc, uint8_t *data, int low)
110 {
111  uint8_t r, g, b;
112  uint16_t color;
113  int i;
114  int array_offset = low ? 0 : 8;
115  uint32_t *palette = (uint32_t *) cc->frame->data[1];
116 
117  for (i = 0; i < 8; i++) {
118  color = (data[2 * i] << 6) + (data[2 * i + 1] & 0x3F);
119  r = ((color >> 8) & 0x000F) * 17;
120  g = ((color >> 4) & 0x000F) * 17;
121  b = ((color ) & 0x000F) * 17;
122  palette[i + array_offset] = 0xFFU << 24 | r << 16 | g << 8 | b;
123  }
124  cc->frame->palette_has_changed = 1;
125 }
126 
128 {
129  unsigned ci, ri;
130  int color;
131  int x, y;
132  int ai;
133  int stride = cc->frame->linesize[0];
134  uint8_t *buf = cc->frame->data[0];
135 
136  ri = (data[2] & 0x1F) * CDG_TILE_HEIGHT + cc->vscroll;
137  ci = (data[3] & 0x3F) * CDG_TILE_WIDTH + cc->hscroll;
138 
139  if (ri > (CDG_FULL_HEIGHT - CDG_TILE_HEIGHT))
140  return AVERROR(EINVAL);
141  if (ci > (CDG_FULL_WIDTH - CDG_TILE_WIDTH))
142  return AVERROR(EINVAL);
143 
144  for (y = 0; y < CDG_TILE_HEIGHT; y++) {
145  for (x = 0; x < CDG_TILE_WIDTH; x++) {
146  if (!((data[4 + y] >> (5 - x)) & 0x01))
147  color = data[0] & 0x0F;
148  else
149  color = data[1] & 0x0F;
150 
151  ai = ci + x + (stride * (ri + y));
152  if (b)
153  color ^= buf[ai];
154  buf[ai] = color;
155  }
156  }
157 
158  return 0;
159 }
160 
161 #define UP 2
162 #define DOWN 1
163 #define LEFT 2
164 #define RIGHT 1
165 
166 static void cdg_copy_rect_buf(int out_tl_x, int out_tl_y, uint8_t *out,
167  int in_tl_x, int in_tl_y, uint8_t *in,
168  int w, int h, int stride)
169 {
170  int y;
171 
172  in += in_tl_x + in_tl_y * stride;
173  out += out_tl_x + out_tl_y * stride;
174  for (y = 0; y < h; y++)
175  memcpy(out + y * stride, in + y * stride, w);
176 }
177 
178 static void cdg_fill_rect_preset(int tl_x, int tl_y, uint8_t *out,
179  int color, int w, int h, int stride)
180 {
181  int y;
182 
183  for (y = tl_y; y < tl_y + h; y++)
184  memset(out + tl_x + y * stride, color, w);
185 }
186 
187 static void cdg_fill_wrapper(int out_tl_x, int out_tl_y, uint8_t *out,
188  int in_tl_x, int in_tl_y, uint8_t *in,
189  int color, int w, int h, int stride, int roll)
190 {
191  if (roll) {
192  cdg_copy_rect_buf(out_tl_x, out_tl_y, out, in_tl_x, in_tl_y,
193  in, w, h, stride);
194  } else {
195  cdg_fill_rect_preset(out_tl_x, out_tl_y, out, color, w, h, stride);
196  }
197 }
198 
200  AVFrame *new_frame, int roll_over)
201 {
202  int color;
203  int hscmd, h_off, hinc, vscmd, v_off, vinc;
204  int y;
205  int stride = cc->frame->linesize[0];
206  uint8_t *in = cc->frame->data[0];
207  uint8_t *out = new_frame->data[0];
208 
209  color = data[0] & 0x0F;
210  hscmd = (data[1] & 0x30) >> 4;
211  vscmd = (data[2] & 0x30) >> 4;
212 
213  h_off = FFMIN(data[1] & 0x07, CDG_BORDER_WIDTH - 1);
214  v_off = FFMIN(data[2] & 0x0F, CDG_BORDER_HEIGHT - 1);
215 
216  /// find the difference and save the offset for cdg_tile_block usage
217  hinc = h_off - cc->hscroll;
218  vinc = v_off - cc->vscroll;
219  cc->hscroll = h_off;
220  cc->vscroll = v_off;
221 
222  if (vscmd == UP)
223  vinc -= 12;
224  if (vscmd == DOWN)
225  vinc += 12;
226  if (hscmd == LEFT)
227  hinc -= 6;
228  if (hscmd == RIGHT)
229  hinc += 6;
230 
231  if (!hinc && !vinc)
232  return;
233 
234  memcpy(new_frame->data[1], cc->frame->data[1], CDG_PALETTE_SIZE * 4);
235 
236  for (y = FFMAX(0, vinc); y < FFMIN(CDG_FULL_HEIGHT + vinc, CDG_FULL_HEIGHT); y++)
237  memcpy(out + FFMAX(0, hinc) + stride * y,
238  in + FFMAX(0, hinc) - hinc + (y - vinc) * stride,
239  FFMIN(stride + hinc, stride));
240 
241  if (vinc > 0)
242  cdg_fill_wrapper(0, 0, out,
243  0, CDG_FULL_HEIGHT - vinc, in, color,
244  stride, vinc, stride, roll_over);
245  else if (vinc < 0)
246  cdg_fill_wrapper(0, CDG_FULL_HEIGHT + vinc, out,
247  0, 0, in, color,
248  stride, -1 * vinc, stride, roll_over);
249 
250  if (hinc > 0)
251  cdg_fill_wrapper(0, 0, out,
252  CDG_FULL_WIDTH - hinc, 0, in, color,
253  hinc, CDG_FULL_HEIGHT, stride, roll_over);
254  else if (hinc < 0)
255  cdg_fill_wrapper(CDG_FULL_WIDTH + hinc, 0, out,
256  0, 0, in, color,
257  -1 * hinc, CDG_FULL_HEIGHT, stride, roll_over);
258 
259 }
260 
262  void *data, int *got_frame, AVPacket *avpkt)
263 {
264  const uint8_t *buf = avpkt->data;
265  int buf_size = avpkt->size;
266  int ret;
267  uint8_t command, inst;
268  uint8_t cdg_data[CDG_DATA_SIZE] = {0};
269  AVFrame *frame = data;
270  CDGraphicsContext *cc = avctx->priv_data;
271 
272  if (buf_size < CDG_MINIMUM_PKT_SIZE) {
273  av_log(avctx, AV_LOG_ERROR, "buffer too small for decoder\n");
274  return AVERROR(EINVAL);
275  }
276  if (buf_size > CDG_HEADER_SIZE + CDG_DATA_SIZE) {
277  av_log(avctx, AV_LOG_ERROR, "buffer too big for decoder\n");
278  return AVERROR(EINVAL);
279  }
280 
281  if ((ret = ff_reget_buffer(avctx, cc->frame)) < 0)
282  return ret;
283  if (!avctx->frame_number) {
284  memset(cc->frame->data[0], 0, cc->frame->linesize[0] * avctx->height);
285  memset(cc->frame->data[1], 0, AVPALETTE_SIZE);
286  }
287 
288  command = bytestream_get_byte(&buf);
289  inst = bytestream_get_byte(&buf);
290  inst &= CDG_MASK;
291  buf += 2; /// skipping 2 unneeded bytes
292 
293  if (buf_size > CDG_HEADER_SIZE)
294  bytestream_get_buffer(&buf, cdg_data, buf_size - CDG_HEADER_SIZE);
295 
296  if ((command & CDG_MASK) == CDG_COMMAND) {
297  switch (inst) {
299  if (!(cdg_data[1] & 0x0F))
300  memset(cc->frame->data[0], cdg_data[0] & 0x0F,
301  cc->frame->linesize[0] * CDG_FULL_HEIGHT);
302  break;
305  if (buf_size - CDG_HEADER_SIZE < CDG_DATA_SIZE) {
306  av_log(avctx, AV_LOG_ERROR, "buffer too small for loading palette\n");
307  return AVERROR(EINVAL);
308  }
309 
310  cdg_load_palette(cc, cdg_data, inst == CDG_INST_LOAD_PAL_LO);
311  break;
313  cdg_border_preset(cc, cdg_data);
314  break;
316  case CDG_INST_TILE_BLOCK:
317  if (buf_size - CDG_HEADER_SIZE < CDG_DATA_SIZE) {
318  av_log(avctx, AV_LOG_ERROR, "buffer too small for drawing tile\n");
319  return AVERROR(EINVAL);
320  }
321 
322  ret = cdg_tile_block(cc, cdg_data, inst == CDG_INST_TILE_BLOCK_XOR);
323  if (ret) {
324  av_log(avctx, AV_LOG_ERROR, "tile is out of range\n");
325  return ret;
326  }
327  break;
330  if (buf_size - CDG_HEADER_SIZE < CDG_MINIMUM_SCROLL_SIZE) {
331  av_log(avctx, AV_LOG_ERROR, "buffer too small for scrolling\n");
332  return AVERROR(EINVAL);
333  }
334 
335  if ((ret = ff_get_buffer(avctx, frame, AV_GET_BUFFER_FLAG_REF)) < 0)
336  return ret;
337 
338  cdg_scroll(cc, cdg_data, frame, inst == CDG_INST_SCROLL_COPY);
339  av_frame_unref(cc->frame);
340  ret = av_frame_ref(cc->frame, frame);
341  if (ret < 0)
342  return ret;
343  break;
344  default:
345  break;
346  }
347 
348  if (!frame->data[0]) {
349  ret = av_frame_ref(frame, cc->frame);
350  if (ret < 0)
351  return ret;
352  }
353  *got_frame = 1;
354  } else {
355  *got_frame = 0;
356  buf_size = 0;
357  }
358 
359  return buf_size;
360 }
361 
363 {
364  CDGraphicsContext *cc = avctx->priv_data;
365 
366  av_frame_free(&cc->frame);
367 
368  return 0;
369 }
370 
372  .name = "cdgraphics",
373  .long_name = NULL_IF_CONFIG_SMALL("CD Graphics video"),
374  .type = AVMEDIA_TYPE_VIDEO,
376  .priv_data_size = sizeof(CDGraphicsContext),
380  .capabilities = CODEC_CAP_DR1,
381 };