libavcodec/ansi.c

   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
  22 /**
  23  * @file
  24  * ASCII/ANSI art decoder
  25  */
  26
  27 #include "libavutil/common.h"
  28 #include "libavutil/lfg.h"
  29 #include "avcodec.h"
  30 #include "cga_data.h"
  31 #include "internal.h"
  32
  33 #define ATTR_BOLD         0x01  /**< Bold/Bright-foreground (mode 1) */
  34 #define ATTR_FAINT        0x02  /**< Faint (mode 2) */
  35 #define ATTR_UNDERLINE    0x08  /**< Underline (mode 4) */
  36 #define ATTR_BLINK        0x10  /**< Blink/Bright-background (mode 5) */
  37 #define ATTR_REVERSE      0x40  /**< Reverse (mode 7) */
  38 #define ATTR_CONCEALED    0x80  /**< Concealed (mode 8) */
  39
  40 #define DEFAULT_FG_COLOR     7  /**< CGA color index */
  41 #define DEFAULT_BG_COLOR     0
  42 #define DEFAULT_SCREEN_MODE  3  /**< 80x25 */
  43
  44 #define FONT_WIDTH           8  /**< Font width */
  45
  46 /** map ansi color index to cga palette index */
  47 static const uint8_t ansi_to_cga[16] = {
  48     0,  4,  2,  6,  1,  5,  3, 7, 8, 12, 10, 14,  9, 13, 11, 15
  49 };
  50
  51 typedef struct {
  52     AVFrame frame;
  53     int x;                /**< x cursor position (pixels) */
  54     int y;                /**< y cursor position (pixels) */
  55     int sx;               /**< saved x cursor position (pixels) */
  56     int sy;               /**< saved y cursor position (pixels) */
  57     const uint8_t* font;  /**< font */
  58     int font_height;      /**< font height */
  59     int attributes;       /**< attribute flags */
  60     int fg;               /**< foreground color */
  61     int bg;               /**< background color */
  62
  63     /* ansi parser state machine */
  64     enum {
  65         STATE_NORMAL = 0,
  66         STATE_ESCAPE,
  67         STATE_CODE,
  68         STATE_MUSIC_PREAMBLE
  69     } state;
  70 #define MAX_NB_ARGS 4
  71     int args[MAX_NB_ARGS];
  72     int nb_args;          /**< number of arguments (may exceed MAX_NB_ARGS) */
  73 } AnsiContext;
  74
  75 static av_cold int decode_init(AVCodecContext *avctx)
  76 {
  77     AnsiContext *s = avctx->priv_data;
  78     avctx->pix_fmt = AV_PIX_FMT_PAL8;
  79
  80     /* defaults */
  81     s->font        = ff_vga16_font;
  82     s->font_height = 16;
  83     s->fg          = DEFAULT_FG_COLOR;
  84     s->bg          = DEFAULT_BG_COLOR;
  85
  86     if (!avctx->width || !avctx->height)
  87         avcodec_set_dimensions(avctx, 80<<3, 25<<4);
  88
  89     return 0;
  90 }
  91
  92 static void hscroll(AVCodecContext *avctx)
  93 {
  94     AnsiContext *s = avctx->priv_data;
  95     int i;
  96
  97     if (s->y < avctx->height - s->font_height) {
  98         s->y += s->font_height;
  99         return;
 100     }
 101
 102     i = 0;
 103     for (; i < avctx->height - s->font_height; i++)
 104         memcpy(s->frame.data[0] + i * s->frame.linesize[0],
 105                s->frame.data[0] + (i + s->font_height) * s->frame.linesize[0],
 106                avctx->width);
 107     for (; i < avctx->height; i++)
 108         memset(s->frame.data[0] + i * s->frame.linesize[0],
 109             DEFAULT_BG_COLOR, avctx->width);
 110 }
 111
 112 static void erase_line(AVCodecContext * avctx, int xoffset, int xlength)
 113 {
 114     AnsiContext *s = avctx->priv_data;
 115     int i;
 116     for (i = 0; i < s->font_height; i++)
 117         memset(s->frame.data[0] + (s->y + i)*s->frame.linesize[0] + xoffset,
 118             DEFAULT_BG_COLOR, xlength);
 119 }
 120
 121 static void erase_screen(AVCodecContext *avctx)
 122 {
 123     AnsiContext *s = avctx->priv_data;
 124     int i;
 125     for (i = 0; i < avctx->height; i++)
 126         memset(s->frame.data[0] + i * s->frame.linesize[0], DEFAULT_BG_COLOR, avctx->width);
 127     s->x = s->y = 0;
 128 }
 129
 130 /**
 131  * Draw character to screen
 132  */
 133 static void draw_char(AVCodecContext *avctx, int c)
 134 {
 135     AnsiContext *s = avctx->priv_data;
 136     int fg = s->fg;
 137     int bg = s->bg;
 138
 139     if ((s->attributes & ATTR_BOLD))
 140         fg += 8;
 141     if ((s->attributes & ATTR_BLINK))
 142         bg += 8;
 143     if ((s->attributes & ATTR_REVERSE))
 144         FFSWAP(int, fg, bg);
 145     if ((s->attributes & ATTR_CONCEALED))
 146         fg = bg;
 147     ff_draw_pc_font(s->frame.data[0] + s->y * s->frame.linesize[0] + s->x,
 148                     s->frame.linesize[0], s->font, s->font_height, c, fg, bg);
 149     s->x += FONT_WIDTH;
 150     if (s->x >= avctx->width) {
 151         s->x = 0;
 152         hscroll(avctx);
 153     }
 154 }
 155
 156 /**
 157  * Execute ANSI escape code
 158  * @return 0 on success, negative on error
 159  */
 160 static int execute_code(AVCodecContext * avctx, int c)
 161 {
 162     AnsiContext *s = avctx->priv_data;
 163     int ret, i, width, height;
 164     switch(c) {
 165     case 'A': //Cursor Up
 166         s->y = FFMAX(s->y - (s->nb_args > 0 ? s->args[0]*s->font_height : s->font_height), 0);
 167         break;
 168     case 'B': //Cursor Down
 169         s->y = FFMIN(s->y + (s->nb_args > 0 ? s->args[0]*s->font_height : s->font_height), avctx->height - s->font_height);
 170         break;
 171     case 'C': //Cursor Right
 172         s->x = FFMIN(s->x + (s->nb_args > 0 ? s->args[0]*FONT_WIDTH : FONT_WIDTH), avctx->width  - FONT_WIDTH);
 173         break;
 174     case 'D': //Cursor Left
 175         s->x = FFMAX(s->x - (s->nb_args > 0 ? s->args[0]*FONT_WIDTH : FONT_WIDTH), 0);
 176         break;
 177     case 'H': //Cursor Position
 178     case 'f': //Horizontal and Vertical Position
 179         s->y = s->nb_args > 0 ? av_clip((s->args[0] - 1)*s->font_height, 0, avctx->height - s->font_height) : 0;
 180         s->x = s->nb_args > 1 ? av_clip((s->args[1] - 1)*FONT_WIDTH,     0, avctx->width  - FONT_WIDTH) : 0;
 181         break;
 182     case 'h': //set creen mode
 183     case 'l': //reset screen mode
 184         if (s->nb_args < 2)
 185             s->args[0] = DEFAULT_SCREEN_MODE;
 186         switch(s->args[0]) {
 187         case 0: case 1: case 4: case 5: case 13: case 19: //320x200 (25 rows)
 188             s->font = ff_cga_font;
 189             s->font_height = 8;
 190             width  = 40<<3;
 191             height = 25<<3;
 192             break;
 193         case 2: case 3: //640x400 (25 rows)
 194             s->font = ff_vga16_font;
 195             s->font_height = 16;
 196             width  = 80<<3;
 197             height = 25<<4;
 198             break;
 199         case 6: case 14: //640x200 (25 rows)
 200             s->font = ff_cga_font;
 201             s->font_height = 8;
 202             width  = 80<<3;
 203             height = 25<<3;
 204             break;
 205         case 7: //set line wrapping
 206             break;
 207         case 15: case 16: //640x350 (43 rows)
 208             s->font = ff_cga_font;
 209             s->font_height = 8;
 210             width  = 80<<3;
 211             height = 43<<3;
 212             break;
 213         case 17: case 18: //640x480 (60 rows)
 214             s->font = ff_cga_font;
 215             s->font_height = 8;
 216             width  = 80<<3;
 217             height = 60<<4;
 218             break;
 219         default:
 220             av_log_ask_for_sample(avctx, "unsupported screen mode\n");
 221         }
 222         if (width != avctx->width || height != avctx->height) {
 223             if (s->frame.data[0])
 224                 avctx->release_buffer(avctx, &s->frame);
 225             avcodec_set_dimensions(avctx, width, height);
 226             ret = ff_get_buffer(avctx, &s->frame);
 227             if (ret < 0) {
 228                 av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
 229                 return ret;
 230             }
 231             s->frame.pict_type           = AV_PICTURE_TYPE_I;
 232             s->frame.palette_has_changed = 1;
 233             memcpy(s->frame.data[1], ff_cga_palette, 16 * 4);
 234             erase_screen(avctx);
 235         } else if (c == 'l') {
 236             erase_screen(avctx);
 237         }
 238         break;
 239     case 'J': //Erase in Page
 240         switch (s->args[0]) {
 241         case 0:
 242             erase_line(avctx, s->x, avctx->width - s->x);
 243             if (s->y < avctx->height - s->font_height)
 244                 memset(s->frame.data[0] + (s->y + s->font_height)*s->frame.linesize[0],
 245                     DEFAULT_BG_COLOR, (avctx->height - s->y - s->font_height)*s->frame.linesize[0]);
 246             break;
 247         case 1:
 248             erase_line(avctx, 0, s->x);
 249             if (s->y > 0)
 250                 memset(s->frame.data[0], DEFAULT_BG_COLOR, s->y * s->frame.linesize[0]);
 251             break;
 252         case 2:
 253             erase_screen(avctx);
 254         }
 255         break;
 256     case 'K': //Erase in Line
 257         switch(s->args[0]) {
 258         case 0:
 259             erase_line(avctx, s->x, avctx->width - s->x);
 260             break;
 261         case 1:
 262             erase_line(avctx, 0, s->x);
 263             break;
 264         case 2:
 265             erase_line(avctx, 0, avctx->width);
 266         }
 267         break;
 268     case 'm': //Select Graphics Rendition
 269         if (s->nb_args == 0) {
 270             s->nb_args = 1;
 271             s->args[0] = 0;
 272         }
 273         for (i = 0; i < FFMIN(s->nb_args, MAX_NB_ARGS); i++) {
 274             int m = s->args[i];
 275             if (m == 0) {
 276                 s->attributes = 0;
 277                 s->fg = DEFAULT_FG_COLOR;
 278                 s->bg = DEFAULT_BG_COLOR;
 279             } else if (m == 1 || m == 2 || m == 4 || m == 5 || m == 7 || m == 8) {
 280                 s->attributes |= 1 << (m - 1);
 281             } else if (m >= 30 && m <= 38) {
 282                 s->fg = ansi_to_cga[m - 30];
 283             } else if (m == 39) {
 284                 s->fg = ansi_to_cga[DEFAULT_FG_COLOR];
 285             } else if (m >= 40 && m <= 47) {
 286                 s->bg = ansi_to_cga[m - 40];
 287             } else if (m == 49) {
 288                 s->fg = ansi_to_cga[DEFAULT_BG_COLOR];
 289             } else {
 290                 av_log_ask_for_sample(avctx, "unsupported rendition parameter\n");
 291             }
 292         }
 293         break;
 294     case 'n': //Device Status Report
 295     case 'R': //report current line and column
 296         /* ignore */
 297         break;
 298     case 's': //Save Cursor Position
 299         s->sx = s->x;
 300         s->sy = s->y;
 301         break;
 302     case 'u': //Restore Cursor Position
 303         s->x = av_clip(s->sx, 0, avctx->width  - FONT_WIDTH);
 304         s->y = av_clip(s->sy, 0, avctx->height - s->font_height);
 305         break;
 306     default:
 307         av_log_ask_for_sample(avctx, "unsupported escape code\n");
 308         break;
 309     }
 310     return 0;
 311 }
 312
 313 static int decode_frame(AVCodecContext *avctx,
 314                             void *data, int *got_frame,
 315                             AVPacket *avpkt)
 316 {
 317     AnsiContext *s = avctx->priv_data;
 318     uint8_t *buf = avpkt->data;
 319     int buf_size = avpkt->size;
 320     const uint8_t *buf_end   = buf+buf_size;
 321     int ret, i, count;
 322
 323     ret = avctx->reget_buffer(avctx, &s->frame);
 324     if (ret < 0){
 325         av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
 326         return ret;
 327     }
 328     if (!avctx->frame_number) {
 329         memset(s->frame.data[0], 0, avctx->height * FFABS(s->frame.linesize[0]));
 330         memset(s->frame.data[1], 0, AVPALETTE_SIZE);
 331     }
 332
 333     s->frame.pict_type           = AV_PICTURE_TYPE_I;
 334     s->frame.palette_has_changed = 1;
 335     memcpy(s->frame.data[1], ff_cga_palette, 16 * 4);
 336
 337     while(buf < buf_end) {
 338         switch(s->state) {
 339         case STATE_NORMAL:
 340             switch (buf[0]) {
 341             case 0x00: //NUL
 342             case 0x07: //BEL
 343             case 0x1A: //SUB
 344                 /* ignore */
 345                 break;
 346             case 0x08: //BS
 347                 s->x = FFMAX(s->x - 1, 0);
 348                 break;
 349             case 0x09: //HT
 350                 i = s->x / FONT_WIDTH;
 351                 count = ((i + 8) & ~7) - i;
 352                 for (i = 0; i < count; i++)
 353                     draw_char(avctx, ' ');
 354                 break;
 355             case 0x0A: //LF
 356                 hscroll(avctx);
 357             case 0x0D: //CR
 358                 s->x = 0;
 359                 break;
 360             case 0x0C: //FF
 361                 erase_screen(avctx);
 362                 break;
 363             case 0x1B: //ESC
 364                 s->state = STATE_ESCAPE;
 365                 break;
 366             default:
 367                 draw_char(avctx, buf[0]);
 368             }
 369             break;
 370         case STATE_ESCAPE:
 371             if (buf[0] == '[') {
 372                 s->state   = STATE_CODE;
 373                 s->nb_args = 0;
 374                 s->args[0] = 0;
 375             } else {
 376                 s->state = STATE_NORMAL;
 377                 draw_char(avctx, 0x1B);
 378                 continue;
 379             }
 380             break;
 381         case STATE_CODE:
 382             switch(buf[0]) {
 383             case '0': case '1': case '2': case '3': case '4':
 384             case '5': case '6': case '7': case '8': case '9':
 385                 if (s->nb_args < MAX_NB_ARGS)
 386                     s->args[s->nb_args] = s->args[s->nb_args] * 10 + buf[0] - '0';
 387                 break;
 388             case ';':
 389                 s->nb_args++;
 390                 if (s->nb_args < MAX_NB_ARGS)
 391                     s->args[s->nb_args] = 0;
 392                 break;
 393             case 'M':
 394                 s->state = STATE_MUSIC_PREAMBLE;
 395                 break;
 396             case '=': case '?':
 397                 /* ignore */
 398                 break;
 399             default:
 400                 if (s->nb_args > MAX_NB_ARGS)
 401                     av_log(avctx, AV_LOG_WARNING, "args overflow (%i)\n", s->nb_args);
 402                 if (s->nb_args < MAX_NB_ARGS && s->args[s->nb_args])
 403                     s->nb_args++;
 404                 if ((ret = execute_code(avctx, buf[0])) < 0)
 405                     return ret;
 406                 s->state = STATE_NORMAL;
 407             }
 408             break;
 409         case STATE_MUSIC_PREAMBLE:
 410             if (buf[0] == 0x0E || buf[0] == 0x1B)
 411                 s->state = STATE_NORMAL;
 412             /* ignore music data */
 413             break;
 414         }
 415         buf++;
 416     }
 417
 418     *got_frame = 1;
 419     *(AVFrame*)data = s->frame;
 420     return buf_size;
 421 }
 422
 423 static av_cold int decode_close(AVCodecContext *avctx)
 424 {
 425     AnsiContext *s = avctx->priv_data;
 426     if (s->frame.data[0])
 427         avctx->release_buffer(avctx, &s->frame);
 428     return 0;
 429 }
 430
 431 AVCodec ff_ansi_decoder = {
 432     .name           = "ansi",
 433     .type           = AVMEDIA_TYPE_VIDEO,
 434     .id             = AV_CODEC_ID_ANSI,
 435     .priv_data_size = sizeof(AnsiContext),
 436     .init           = decode_init,
 437     .close          = decode_close,
 438     .decode         = decode_frame,
 439     .capabilities   = CODEC_CAP_DR1,
 440     .long_name      = NULL_IF_CONFIG_SMALL("ASCII/ANSI art"),
 441 };