ansi.c
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1 /*
2  * ASCII/ANSI art decoder
3  * Copyright (c) 2010 Peter Ross <pross@xvid.org>
4  *
5  * This file is part of Libav.
6  *
7  * Libav 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  * Libav 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 Libav; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
27 #include "libavutil/lfg.h"
28 #include "avcodec.h"
29 #include "cga_data.h"
30 
31 #define ATTR_BOLD 0x01
32 #define ATTR_FAINT 0x02
33 #define ATTR_UNDERLINE 0x08
34 #define ATTR_BLINK 0x10
35 #define ATTR_REVERSE 0x40
36 #define ATTR_CONCEALED 0x80
38 #define DEFAULT_FG_COLOR 7
39 #define DEFAULT_BG_COLOR 0
40 #define DEFAULT_SCREEN_MODE 3
42 #define FONT_WIDTH 8
45 static const uint8_t ansi_to_cga[16] = {
46  0, 4, 2, 6, 1, 5, 3, 7, 8, 12, 10, 14, 9, 13, 11, 15
47 };
48 
49 typedef struct {
51  int x;
52  int y;
53  int sx;
54  int sy;
55  const uint8_t* font;
57  int attributes;
58  int fg;
59  int bg;
61  /* ansi parser state machine */
62  enum {
63  STATE_NORMAL = 0,
66  STATE_MUSIC_PREAMBLE
67  } state;
68 #define MAX_NB_ARGS 4
69  int args[MAX_NB_ARGS];
70  int nb_args;
71 } AnsiContext;
72 
74 {
75  AnsiContext *s = avctx->priv_data;
76  avctx->pix_fmt = PIX_FMT_PAL8;
77 
78  /* defaults */
79  s->font = ff_vga16_font;
80  s->font_height = 16;
81  s->fg = DEFAULT_FG_COLOR;
82  s->bg = DEFAULT_BG_COLOR;
83 
84  if (!avctx->width || !avctx->height)
85  avcodec_set_dimensions(avctx, 80<<3, 25<<4);
86 
87  return 0;
88 }
89 
90 static void hscroll(AVCodecContext *avctx)
91 {
92  AnsiContext *s = avctx->priv_data;
93  int i;
94 
95  if (s->y < avctx->height - s->font_height) {
96  s->y += s->font_height;
97  return;
98  }
99 
100  i = 0;
101  for (; i < avctx->height - s->font_height; i++)
102  memcpy(s->frame.data[0] + i * s->frame.linesize[0],
103  s->frame.data[0] + (i + s->font_height) * s->frame.linesize[0],
104  avctx->width);
105  for (; i < avctx->height; i++)
106  memset(s->frame.data[0] + i * s->frame.linesize[0],
107  DEFAULT_BG_COLOR, avctx->width);
108 }
109 
110 static void erase_line(AVCodecContext * avctx, int xoffset, int xlength)
111 {
112  AnsiContext *s = avctx->priv_data;
113  int i;
114  for (i = 0; i < s->font_height; i++)
115  memset(s->frame.data[0] + (s->y + i)*s->frame.linesize[0] + xoffset,
116  DEFAULT_BG_COLOR, xlength);
117 }
118 
119 static void erase_screen(AVCodecContext *avctx)
120 {
121  AnsiContext *s = avctx->priv_data;
122  int i;
123  for (i = 0; i < avctx->height; i++)
124  memset(s->frame.data[0] + i * s->frame.linesize[0], DEFAULT_BG_COLOR, avctx->width);
125  s->x = s->y = 0;
126 }
127 
131 static void draw_char(AVCodecContext *avctx, int c)
132 {
133  AnsiContext *s = avctx->priv_data;
134  int fg = s->fg;
135  int bg = s->bg;
136 
137  if ((s->attributes & ATTR_BOLD))
138  fg += 8;
139  if ((s->attributes & ATTR_BLINK))
140  bg += 8;
141  if ((s->attributes & ATTR_REVERSE))
142  FFSWAP(int, fg, bg);
143  if ((s->attributes & ATTR_CONCEALED))
144  fg = bg;
145  ff_draw_pc_font(s->frame.data[0] + s->y * s->frame.linesize[0] + s->x,
146  s->frame.linesize[0], s->font, s->font_height, c, fg, bg);
147  s->x += FONT_WIDTH;
148  if (s->x >= avctx->width) {
149  s->x = 0;
150  hscroll(avctx);
151  }
152 }
153 
158 static int execute_code(AVCodecContext * avctx, int c)
159 {
160  AnsiContext *s = avctx->priv_data;
161  int ret, i, width, height;
162  switch(c) {
163  case 'A': //Cursor Up
164  s->y = FFMAX(s->y - (s->nb_args > 0 ? s->args[0]*s->font_height : s->font_height), 0);
165  break;
166  case 'B': //Cursor Down
167  s->y = FFMIN(s->y + (s->nb_args > 0 ? s->args[0]*s->font_height : s->font_height), avctx->height - s->font_height);
168  break;
169  case 'C': //Cursor Right
170  s->x = FFMIN(s->x + (s->nb_args > 0 ? s->args[0]*FONT_WIDTH : FONT_WIDTH), avctx->width - FONT_WIDTH);
171  break;
172  case 'D': //Cursor Left
173  s->x = FFMAX(s->x - (s->nb_args > 0 ? s->args[0]*FONT_WIDTH : FONT_WIDTH), 0);
174  break;
175  case 'H': //Cursor Position
176  case 'f': //Horizontal and Vertical Position
177  s->y = s->nb_args > 0 ? av_clip((s->args[0] - 1)*s->font_height, 0, avctx->height - s->font_height) : 0;
178  s->x = s->nb_args > 1 ? av_clip((s->args[1] - 1)*FONT_WIDTH, 0, avctx->width - FONT_WIDTH) : 0;
179  break;
180  case 'h': //set creen mode
181  case 'l': //reset screen mode
182  if (s->nb_args < 2)
183  s->args[0] = DEFAULT_SCREEN_MODE;
184  switch(s->args[0]) {
185  case 0: case 1: case 4: case 5: case 13: case 19: //320x200 (25 rows)
186  s->font = ff_cga_font;
187  s->font_height = 8;
188  width = 40<<3;
189  height = 25<<3;
190  break;
191  case 2: case 3: //640x400 (25 rows)
192  s->font = ff_vga16_font;
193  s->font_height = 16;
194  width = 80<<3;
195  height = 25<<4;
196  break;
197  case 6: case 14: //640x200 (25 rows)
198  s->font = ff_cga_font;
199  s->font_height = 8;
200  width = 80<<3;
201  height = 25<<3;
202  break;
203  case 7: //set line wrapping
204  break;
205  case 15: case 16: //640x350 (43 rows)
206  s->font = ff_cga_font;
207  s->font_height = 8;
208  width = 80<<3;
209  height = 43<<3;
210  break;
211  case 17: case 18: //640x480 (60 rows)
212  s->font = ff_cga_font;
213  s->font_height = 8;
214  width = 80<<3;
215  height = 60<<4;
216  break;
217  default:
218  av_log_ask_for_sample(avctx, "unsupported screen mode\n");
219  }
220  if (width != avctx->width || height != avctx->height) {
221  if (s->frame.data[0])
222  avctx->release_buffer(avctx, &s->frame);
223  avcodec_set_dimensions(avctx, width, height);
224  ret = avctx->get_buffer(avctx, &s->frame);
225  if (ret < 0) {
226  av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
227  return ret;
228  }
230  s->frame.palette_has_changed = 1;
231  memcpy(s->frame.data[1], ff_cga_palette, 16 * 4);
232  erase_screen(avctx);
233  } else if (c == 'l') {
234  erase_screen(avctx);
235  }
236  break;
237  case 'J': //Erase in Page
238  switch (s->args[0]) {
239  case 0:
240  erase_line(avctx, s->x, avctx->width - s->x);
241  if (s->y < avctx->height - s->font_height)
242  memset(s->frame.data[0] + (s->y + s->font_height)*s->frame.linesize[0],
243  DEFAULT_BG_COLOR, (avctx->height - s->y - s->font_height)*s->frame.linesize[0]);
244  break;
245  case 1:
246  erase_line(avctx, 0, s->x);
247  if (s->y > 0)
248  memset(s->frame.data[0], DEFAULT_BG_COLOR, s->y * s->frame.linesize[0]);
249  break;
250  case 2:
251  erase_screen(avctx);
252  }
253  break;
254  case 'K': //Erase in Line
255  switch(s->args[0]) {
256  case 0:
257  erase_line(avctx, s->x, avctx->width - s->x);
258  break;
259  case 1:
260  erase_line(avctx, 0, s->x);
261  break;
262  case 2:
263  erase_line(avctx, 0, avctx->width);
264  }
265  break;
266  case 'm': //Select Graphics Rendition
267  if (s->nb_args == 0) {
268  s->nb_args = 1;
269  s->args[0] = 0;
270  }
271  for (i = 0; i < FFMIN(s->nb_args, MAX_NB_ARGS); i++) {
272  int m = s->args[i];
273  if (m == 0) {
274  s->attributes = 0;
275  s->fg = DEFAULT_FG_COLOR;
276  s->bg = DEFAULT_BG_COLOR;
277  } else if (m == 1 || m == 2 || m == 4 || m == 5 || m == 7 || m == 8) {
278  s->attributes |= 1 << (m - 1);
279  } else if (m >= 30 && m <= 38) {
280  s->fg = ansi_to_cga[m - 30];
281  } else if (m == 39) {
283  } else if (m >= 40 && m <= 47) {
284  s->bg = ansi_to_cga[m - 40];
285  } else if (m == 49) {
287  } else {
288  av_log_ask_for_sample(avctx, "unsupported rendition parameter\n");
289  }
290  }
291  break;
292  case 'n': //Device Status Report
293  case 'R': //report current line and column
294  /* ignore */
295  break;
296  case 's': //Save Cursor Position
297  s->sx = s->x;
298  s->sy = s->y;
299  break;
300  case 'u': //Restore Cursor Position
301  s->x = av_clip(s->sx, 0, avctx->width - FONT_WIDTH);
302  s->y = av_clip(s->sy, 0, avctx->height - s->font_height);
303  break;
304  default:
305  av_log_ask_for_sample(avctx, "unsupported escape code\n");
306  break;
307  }
308  return 0;
309 }
310 
311 static int decode_frame(AVCodecContext *avctx,
312  void *data, int *data_size,
313  AVPacket *avpkt)
314 {
315  AnsiContext *s = avctx->priv_data;
316  uint8_t *buf = avpkt->data;
317  int buf_size = avpkt->size;
318  const uint8_t *buf_end = buf+buf_size;
319  int ret, i, count;
320 
321  ret = avctx->reget_buffer(avctx, &s->frame);
322  if (ret < 0){
323  av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
324  return ret;
325  }
327  s->frame.palette_has_changed = 1;
328  memcpy(s->frame.data[1], ff_cga_palette, 16 * 4);
329 
330  while(buf < buf_end) {
331  switch(s->state) {
332  case STATE_NORMAL:
333  switch (buf[0]) {
334  case 0x00: //NUL
335  case 0x07: //BEL
336  case 0x1A: //SUB
337  /* ignore */
338  break;
339  case 0x08: //BS
340  s->x = FFMAX(s->x - 1, 0);
341  break;
342  case 0x09: //HT
343  i = s->x / FONT_WIDTH;
344  count = ((i + 8) & ~7) - i;
345  for (i = 0; i < count; i++)
346  draw_char(avctx, ' ');
347  break;
348  case 0x0A: //LF
349  hscroll(avctx);
350  case 0x0D: //CR
351  s->x = 0;
352  break;
353  case 0x0C: //FF
354  erase_screen(avctx);
355  break;
356  case 0x1B: //ESC
357  s->state = STATE_ESCAPE;
358  break;
359  default:
360  draw_char(avctx, buf[0]);
361  }
362  break;
363  case STATE_ESCAPE:
364  if (buf[0] == '[') {
365  s->state = STATE_CODE;
366  s->nb_args = 0;
367  s->args[0] = 0;
368  } else {
369  s->state = STATE_NORMAL;
370  draw_char(avctx, 0x1B);
371  return -1;
372  continue;
373  }
374  break;
375  case STATE_CODE:
376  switch(buf[0]) {
377  case '0': case '1': case '2': case '3': case '4':
378  case '5': case '6': case '7': case '8': case '9':
379  if (s->nb_args < MAX_NB_ARGS)
380  s->args[s->nb_args] = s->args[s->nb_args] * 10 + buf[0] - '0';
381  break;
382  case ';':
383  s->nb_args++;
384  if (s->nb_args < MAX_NB_ARGS)
385  s->args[s->nb_args] = 0;
386  break;
387  case 'M':
388  s->state = STATE_MUSIC_PREAMBLE;
389  break;
390  case '=': case '?':
391  /* ignore */
392  break;
393  default:
394  if (s->nb_args > MAX_NB_ARGS)
395  av_log(avctx, AV_LOG_WARNING, "args overflow (%i)\n", s->nb_args);
396  if (s->nb_args < MAX_NB_ARGS && s->args[s->nb_args])
397  s->nb_args++;
398  if (execute_code(avctx, buf[0]) < 0)
399  return -1;
400  s->state = STATE_NORMAL;
401  }
402  break;
403  case STATE_MUSIC_PREAMBLE:
404  if (buf[0] == 0x0E || buf[0] == 0x1B)
405  s->state = STATE_NORMAL;
406  /* ignore music data */
407  break;
408  }
409  buf++;
410  }
411 
412  *data_size = sizeof(AVFrame);
413  *(AVFrame*)data = s->frame;
414  return buf_size;
415 }
416 
418 {
419  AnsiContext *s = avctx->priv_data;
420  if (s->frame.data[0])
421  avctx->release_buffer(avctx, &s->frame);
422  return 0;
423 }
424 
426  .name = "ansi",
427  .type = AVMEDIA_TYPE_VIDEO,
428  .id = CODEC_ID_ANSI,
429  .priv_data_size = sizeof(AnsiContext),
430  .init = decode_init,
431  .close = decode_close,
432  .decode = decode_frame,
433  .capabilities = CODEC_CAP_DR1,
434  .long_name = NULL_IF_CONFIG_SMALL("ASCII/ANSI art"),
435 };