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