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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 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 /**
23  * @file
24  * ASCII/ANSI art decoder
25  */
26 
27 #include "libavutil/common.h"
28 #include "libavutil/frame.h"
29 #include "libavutil/lfg.h"
30 #include "libavutil/xga_font_data.h"
31 #include "avcodec.h"
32 #include "cga_data.h"
33 #include "internal.h"
34 
35 #define ATTR_BOLD 0x01 /**< Bold/Bright-foreground (mode 1) */
36 #define ATTR_FAINT 0x02 /**< Faint (mode 2) */
37 #define ATTR_UNDERLINE 0x08 /**< Underline (mode 4) */
38 #define ATTR_BLINK 0x10 /**< Blink/Bright-background (mode 5) */
39 #define ATTR_REVERSE 0x40 /**< Reverse (mode 7) */
40 #define ATTR_CONCEALED 0x80 /**< Concealed (mode 8) */
41 
42 #define DEFAULT_FG_COLOR 7 /**< CGA color index */
43 #define DEFAULT_BG_COLOR 0
44 #define DEFAULT_SCREEN_MODE 3 /**< 80x25 */
45 
46 #define FONT_WIDTH 8 /**< Font width */
47 
48 /** map ansi color index to cga palette index */
49 static const uint8_t ansi_to_cga[16] = {
50  0, 4, 2, 6, 1, 5, 3, 7, 8, 12, 10, 14, 9, 13, 11, 15
51 };
52 
53 typedef struct AnsiContext {
54  AVFrame *frame;
55  int x; /**< x cursor position (pixels) */
56  int y; /**< y cursor position (pixels) */
57  int sx; /**< saved x cursor position (pixels) */
58  int sy; /**< saved y cursor position (pixels) */
59  const uint8_t* font; /**< font */
60  int font_height; /**< font height */
61  int attributes; /**< attribute flags */
62  int fg; /**< foreground color */
63  int bg; /**< background color */
64  int first_frame;
65 
66  /* ansi parser state machine */
67  enum {
68  STATE_NORMAL = 0,
69  STATE_ESCAPE,
70  STATE_CODE,
71  STATE_MUSIC_PREAMBLE
72  } state;
73 #define MAX_NB_ARGS 4
74  int args[MAX_NB_ARGS];
75  int nb_args; /**< number of arguments (may exceed MAX_NB_ARGS) */
76 } AnsiContext;
77 
78 static av_cold int decode_init(AVCodecContext *avctx)
79 {
80  AnsiContext *s = avctx->priv_data;
81  avctx->pix_fmt = AV_PIX_FMT_PAL8;
82 
83  s->frame = av_frame_alloc();
84  if (!s->frame)
85  return AVERROR(ENOMEM);
86 
87  /* defaults */
88  s->font = avpriv_vga16_font;
89  s->font_height = 16;
90  s->fg = DEFAULT_FG_COLOR;
91  s->bg = DEFAULT_BG_COLOR;
92 
93  if (!avctx->width || !avctx->height) {
94  int ret = ff_set_dimensions(avctx, 80 << 3, 25 << 4);
95  if (ret < 0)
96  return ret;
97  }
98  return 0;
99 }
100 
101 static void set_palette(uint32_t *pal)
102 {
103  int r, g, b;
104  memcpy(pal, ff_cga_palette, 16 * 4);
105  pal += 16;
106 #define COLOR(x) ((x) * 40 + 55)
107  for (r = 0; r < 6; r++)
108  for (g = 0; g < 6; g++)
109  for (b = 0; b < 6; b++)
110  *pal++ = 0xFF000000 | (COLOR(r) << 16) | (COLOR(g) << 8) | COLOR(b);
111 #define GRAY(x) ((x) * 10 + 8)
112  for (g = 0; g < 24; g++)
113  *pal++ = 0xFF000000 | (GRAY(g) << 16) | (GRAY(g) << 8) | GRAY(g);
114 }
115 
116 static void hscroll(AVCodecContext *avctx)
117 {
118  AnsiContext *s = avctx->priv_data;
119  int i;
120 
121  if (s->y <= avctx->height - 2*s->font_height) {
122  s->y += s->font_height;
123  return;
124  }
125 
126  i = 0;
127  for (; i < avctx->height - s->font_height; i++)
128  memcpy(s->frame->data[0] + i * s->frame->linesize[0],
129  s->frame->data[0] + (i + s->font_height) * s->frame->linesize[0],
130  avctx->width);
131  for (; i < avctx->height; i++)
132  memset(s->frame->data[0] + i * s->frame->linesize[0],
133  DEFAULT_BG_COLOR, avctx->width);
134 }
135 
136 static void erase_line(AVCodecContext * avctx, int xoffset, int xlength)
137 {
138  AnsiContext *s = avctx->priv_data;
139  int i;
140  for (i = 0; i < s->font_height; i++)
141  memset(s->frame->data[0] + (s->y + i)*s->frame->linesize[0] + xoffset,
142  DEFAULT_BG_COLOR, xlength);
143 }
144 
145 static void erase_screen(AVCodecContext *avctx)
146 {
147  AnsiContext *s = avctx->priv_data;
148  int i;
149  for (i = 0; i < avctx->height; i++)
150  memset(s->frame->data[0] + i * s->frame->linesize[0], DEFAULT_BG_COLOR, avctx->width);
151  s->x = s->y = 0;
152 }
153 
154 /**
155  * Draw character to screen
156  */
157 static void draw_char(AVCodecContext *avctx, int c)
158 {
159  AnsiContext *s = avctx->priv_data;
160  int fg = s->fg;
161  int bg = s->bg;
162 
163  if ((s->attributes & ATTR_BOLD))
164  fg += 8;
165  if ((s->attributes & ATTR_BLINK))
166  bg += 8;
167  if ((s->attributes & ATTR_REVERSE))
168  FFSWAP(int, fg, bg);
169  if ((s->attributes & ATTR_CONCEALED))
170  fg = bg;
171  ff_draw_pc_font(s->frame->data[0] + s->y * s->frame->linesize[0] + s->x,
172  s->frame->linesize[0], s->font, s->font_height, c, fg, bg);
173  s->x += FONT_WIDTH;
174  if (s->x > avctx->width - FONT_WIDTH) {
175  s->x = 0;
176  hscroll(avctx);
177  }
178 }
179 
180 /**
181  * Execute ANSI escape code
182  * @return 0 on success, negative on error
183  */
184 static int execute_code(AVCodecContext * avctx, int c)
185 {
186  AnsiContext *s = avctx->priv_data;
187  int ret, i;
188  int width = avctx->width;
189  int height = avctx->height;
190 
191  switch(c) {
192  case 'A': //Cursor Up
193  s->y = FFMAX(s->y - (s->nb_args > 0 ? s->args[0]*s->font_height : s->font_height), 0);
194  break;
195  case 'B': //Cursor Down
196  s->y = FFMIN(s->y + (s->nb_args > 0 ? s->args[0]*s->font_height : s->font_height), avctx->height - s->font_height);
197  break;
198  case 'C': //Cursor Right
199  s->x = FFMIN(s->x + (s->nb_args > 0 ? s->args[0]*FONT_WIDTH : FONT_WIDTH), avctx->width - FONT_WIDTH);
200  break;
201  case 'D': //Cursor Left
202  s->x = FFMAX(s->x - (s->nb_args > 0 ? s->args[0]*FONT_WIDTH : FONT_WIDTH), 0);
203  break;
204  case 'H': //Cursor Position
205  case 'f': //Horizontal and Vertical Position
206  s->y = s->nb_args > 0 ? av_clip((s->args[0] - 1)*s->font_height, 0, avctx->height - s->font_height) : 0;
207  s->x = s->nb_args > 1 ? av_clip((s->args[1] - 1)*FONT_WIDTH, 0, avctx->width - FONT_WIDTH) : 0;
208  break;
209  case 'h': //set creen mode
210  case 'l': //reset screen mode
211  if (s->nb_args < 2)
212  s->args[0] = DEFAULT_SCREEN_MODE;
213  switch(s->args[0]) {
214  case 0: case 1: case 4: case 5: case 13: case 19: //320x200 (25 rows)
215  s->font = avpriv_cga_font;
216  s->font_height = 8;
217  width = 40<<3;
218  height = 25<<3;
219  break;
220  case 2: case 3: //640x400 (25 rows)
221  s->font = avpriv_vga16_font;
222  s->font_height = 16;
223  width = 80<<3;
224  height = 25<<4;
225  break;
226  case 6: case 14: //640x200 (25 rows)
227  s->font = avpriv_cga_font;
228  s->font_height = 8;
229  width = 80<<3;
230  height = 25<<3;
231  break;
232  case 7: //set line wrapping
233  break;
234  case 15: case 16: //640x350 (43 rows)
235  s->font = avpriv_cga_font;
236  s->font_height = 8;
237  width = 80<<3;
238  height = 43<<3;
239  break;
240  case 17: case 18: //640x480 (60 rows)
241  s->font = avpriv_cga_font;
242  s->font_height = 8;
243  width = 80<<3;
244  height = 60<<4;
245  break;
246  default:
247  avpriv_request_sample(avctx, "Unsupported screen mode");
248  }
249  s->x = av_clip(s->x, 0, width - FONT_WIDTH);
250  s->y = av_clip(s->y, 0, height - s->font_height);
251  if (width != avctx->width || height != avctx->height) {
252  av_frame_unref(s->frame);
253  ret = ff_set_dimensions(avctx, width, height);
254  if (ret < 0)
255  return ret;
256  if ((ret = ff_get_buffer(avctx, s->frame,
257  AV_GET_BUFFER_FLAG_REF)) < 0)
258  return ret;
259  s->frame->pict_type = AV_PICTURE_TYPE_I;
260  s->frame->palette_has_changed = 1;
261  set_palette((uint32_t *)s->frame->data[1]);
262  erase_screen(avctx);
263  } else if (c == 'l') {
264  erase_screen(avctx);
265  }
266  break;
267  case 'J': //Erase in Page
268  switch (s->args[0]) {
269  case 0:
270  erase_line(avctx, s->x, avctx->width - s->x);
271  if (s->y < avctx->height - s->font_height)
272  memset(s->frame->data[0] + (s->y + s->font_height)*s->frame->linesize[0],
273  DEFAULT_BG_COLOR, (avctx->height - s->y - s->font_height)*s->frame->linesize[0]);
274  break;
275  case 1:
276  erase_line(avctx, 0, s->x);
277  if (s->y > 0)
278  memset(s->frame->data[0], DEFAULT_BG_COLOR, s->y * s->frame->linesize[0]);
279  break;
280  case 2:
281  erase_screen(avctx);
282  }
283  break;
284  case 'K': //Erase in Line
285  switch(s->args[0]) {
286  case 0:
287  erase_line(avctx, s->x, avctx->width - s->x);
288  break;
289  case 1:
290  erase_line(avctx, 0, s->x);
291  break;
292  case 2:
293  erase_line(avctx, 0, avctx->width);
294  }
295  break;
296  case 'm': //Select Graphics Rendition
297  if (s->nb_args == 0) {
298  s->nb_args = 1;
299  s->args[0] = 0;
300  }
301  for (i = 0; i < FFMIN(s->nb_args, MAX_NB_ARGS); i++) {
302  int m = s->args[i];
303  if (m == 0) {
304  s->attributes = 0;
305  s->fg = DEFAULT_FG_COLOR;
306  s->bg = DEFAULT_BG_COLOR;
307  } else if (m == 1 || m == 2 || m == 4 || m == 5 || m == 7 || m == 8) {
308  s->attributes |= 1 << (m - 1);
309  } else if (m >= 30 && m <= 37) {
310  s->fg = ansi_to_cga[m - 30];
311  } else if (m == 38 && i + 2 < FFMIN(s->nb_args, MAX_NB_ARGS) && s->args[i + 1] == 5 && s->args[i + 2] < 256) {
312  int index = s->args[i + 2];
313  s->fg = index < 16 ? ansi_to_cga[index] : index;
314  i += 2;
315  } else if (m == 39) {
316  s->fg = ansi_to_cga[DEFAULT_FG_COLOR];
317  } else if (m >= 40 && m <= 47) {
318  s->bg = ansi_to_cga[m - 40];
319  } else if (m == 48 && i + 2 < FFMIN(s->nb_args, MAX_NB_ARGS) && s->args[i + 1] == 5 && s->args[i + 2] < 256) {
320  int index = s->args[i + 2];
321  s->bg = index < 16 ? ansi_to_cga[index] : index;
322  i += 2;
323  } else if (m == 49) {
324  s->fg = ansi_to_cga[DEFAULT_BG_COLOR];
325  } else {
326  avpriv_request_sample(avctx, "Unsupported rendition parameter");
327  }
328  }
329  break;
330  case 'n': //Device Status Report
331  case 'R': //report current line and column
332  /* ignore */
333  break;
334  case 's': //Save Cursor Position
335  s->sx = s->x;
336  s->sy = s->y;
337  break;
338  case 'u': //Restore Cursor Position
339  s->x = av_clip(s->sx, 0, avctx->width - FONT_WIDTH);
340  s->y = av_clip(s->sy, 0, avctx->height - s->font_height);
341  break;
342  default:
343  avpriv_request_sample(avctx, "Unknown escape code");
344  break;
345  }
346  s->x = av_clip(s->x, 0, avctx->width - FONT_WIDTH);
347  s->y = av_clip(s->y, 0, avctx->height - s->font_height);
348  return 0;
349 }
350 
351 static int decode_frame(AVCodecContext *avctx,
352  void *data, int *got_frame,
353  AVPacket *avpkt)
354 {
355  AnsiContext *s = avctx->priv_data;
356  uint8_t *buf = avpkt->data;
357  int buf_size = avpkt->size;
358  const uint8_t *buf_end = buf+buf_size;
359  int ret, i, count;
360 
361  if ((ret = ff_reget_buffer(avctx, s->frame)) < 0)
362  return ret;
363  if (!avctx->frame_number) {
364  for (i=0; i<avctx->height; i++)
365  memset(s->frame->data[0]+ i*s->frame->linesize[0], 0, avctx->width);
366  memset(s->frame->data[1], 0, AVPALETTE_SIZE);
367  }
368 
369  s->frame->pict_type = AV_PICTURE_TYPE_I;
370  s->frame->palette_has_changed = 1;
371  set_palette((uint32_t *)s->frame->data[1]);
372  if (!s->first_frame) {
373  erase_screen(avctx);
374  s->first_frame = 1;
375  }
376 
377  while(buf < buf_end) {
378  switch(s->state) {
379  case STATE_NORMAL:
380  switch (buf[0]) {
381  case 0x00: //NUL
382  case 0x07: //BEL
383  case 0x1A: //SUB
384  /* ignore */
385  break;
386  case 0x08: //BS
387  s->x = FFMAX(s->x - 1, 0);
388  break;
389  case 0x09: //HT
390  i = s->x / FONT_WIDTH;
391  count = ((i + 8) & ~7) - i;
392  for (i = 0; i < count; i++)
393  draw_char(avctx, ' ');
394  break;
395  case 0x0A: //LF
396  hscroll(avctx);
397  case 0x0D: //CR
398  s->x = 0;
399  break;
400  case 0x0C: //FF
401  erase_screen(avctx);
402  break;
403  case 0x1B: //ESC
404  s->state = STATE_ESCAPE;
405  break;
406  default:
407  draw_char(avctx, buf[0]);
408  }
409  break;
410  case STATE_ESCAPE:
411  if (buf[0] == '[') {
412  s->state = STATE_CODE;
413  s->nb_args = 0;
414  s->args[0] = -1;
415  } else {
416  s->state = STATE_NORMAL;
417  draw_char(avctx, 0x1B);
418  continue;
419  }
420  break;
421  case STATE_CODE:
422  switch(buf[0]) {
423  case '0': case '1': case '2': case '3': case '4':
424  case '5': case '6': case '7': case '8': case '9':
425  if (s->nb_args < MAX_NB_ARGS && s->args[s->nb_args] < 6553)
426  s->args[s->nb_args] = FFMAX(s->args[s->nb_args], 0) * 10 + buf[0] - '0';
427  break;
428  case ';':
429  s->nb_args++;
430  if (s->nb_args < MAX_NB_ARGS)
431  s->args[s->nb_args] = 0;
432  break;
433  case 'M':
434  s->state = STATE_MUSIC_PREAMBLE;
435  break;
436  case '=': case '?':
437  /* ignore */
438  break;
439  default:
440  if (s->nb_args > MAX_NB_ARGS)
441  av_log(avctx, AV_LOG_WARNING, "args overflow (%i)\n", s->nb_args);
442  if (s->nb_args < MAX_NB_ARGS && s->args[s->nb_args] >= 0)
443  s->nb_args++;
444  if ((ret = execute_code(avctx, buf[0])) < 0)
445  return ret;
446  s->state = STATE_NORMAL;
447  }
448  break;
449  case STATE_MUSIC_PREAMBLE:
450  if (buf[0] == 0x0E || buf[0] == 0x1B)
451  s->state = STATE_NORMAL;
452  /* ignore music data */
453  break;
454  }
455  buf++;
456  }
457 
458  *got_frame = 1;
459  if ((ret = av_frame_ref(data, s->frame)) < 0)
460  return ret;
461  return buf_size;
462 }
463 
464 static av_cold int decode_close(AVCodecContext *avctx)
465 {
466  AnsiContext *s = avctx->priv_data;
467 
468  av_frame_free(&s->frame);
469  return 0;
470 }
471 
472 AVCodec ff_ansi_decoder = {
473  .name = "ansi",
474  .long_name = NULL_IF_CONFIG_SMALL("ASCII/ANSI art"),
475  .type = AVMEDIA_TYPE_VIDEO,
476  .id = AV_CODEC_ID_ANSI,
477  .priv_data_size = sizeof(AnsiContext),
478  .init = decode_init,
479  .close = decode_close,
480  .decode = decode_frame,
481  .capabilities = CODEC_CAP_DR1,
482 };
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