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/frame.h"
  29 #include "libavutil/lfg.h"
  30 #include "avcodec.h"
  31 #include "cga_data.h"
  32 #include "internal.h"
  33
  34 #define ATTR_BOLD         0x01  /**< Bold/Bright-foreground (mode 1) */
  35 #define ATTR_FAINT        0x02  /**< Faint (mode 2) */
  36 #define ATTR_UNDERLINE    0x08  /**< Underline (mode 4) */
  37 #define ATTR_BLINK        0x10  /**< Blink/Bright-background (mode 5) */
  38 #define ATTR_REVERSE      0x40  /**< Reverse (mode 7) */
  39 #define ATTR_CONCEALED    0x80  /**< Concealed (mode 8) */
  40
  41 #define DEFAULT_FG_COLOR     7  /**< CGA color index */
  42 #define DEFAULT_BG_COLOR     0
  43 #define DEFAULT_SCREEN_MODE  3  /**< 80x25 */
  44
  45 #define FONT_WIDTH           8  /**< Font width */
  46
  47 /** map ansi color index to cga palette index */
  48 static const uint8_t ansi_to_cga[16] = {
  49     0,  4,  2,  6,  1,  5,  3, 7, 8, 12, 10, 14,  9, 13, 11, 15
  50 };
  51
  52 typedef struct AnsiContext {
  53     AVFrame *frame;
  54     int x;                /**< x cursor position (pixels) */
  55     int y;                /**< y cursor position (pixels) */
  56     int sx;               /**< saved x cursor position (pixels) */
  57     int sy;               /**< saved y cursor position (pixels) */
  58     const uint8_t* font;  /**< font */
  59     int font_height;      /**< font height */
  60     int attributes;       /**< attribute flags */
  61     int fg;               /**< foreground color */
  62     int bg;               /**< background color */
  63
  64     /* ansi parser state machine */
  65     enum {
  66         STATE_NORMAL = 0,
  67         STATE_ESCAPE,
  68         STATE_CODE,
  69         STATE_MUSIC_PREAMBLE
  70     } state;
  71 #define MAX_NB_ARGS 4
  72     int args[MAX_NB_ARGS];
  73     int nb_args;          /**< number of arguments (may exceed MAX_NB_ARGS) */
  74 } AnsiContext;
  75
  76 static av_cold int decode_init(AVCodecContext *avctx)
  77 {
  78     AnsiContext *s = avctx->priv_data;
  79     avctx->pix_fmt = AV_PIX_FMT_PAL8;
  80
  81     s->frame = av_frame_alloc();
  82     if (!s->frame)
  83         return AVERROR(ENOMEM);
  84
  85     /* defaults */
  86     s->font        = ff_vga16_font;
  87     s->font_height = 16;
  88     s->fg          = DEFAULT_FG_COLOR;
  89     s->bg          = DEFAULT_BG_COLOR;
  90
  91     if (!avctx->width || !avctx->height) {
  92         int ret = ff_set_dimensions(avctx, 80 << 3, 25 << 4);
  93         if (ret < 0)
  94             return ret;
  95     }
  96     return 0;
  97 }
  98
  99 static void hscroll(AVCodecContext *avctx)
 100 {
 101     AnsiContext *s = avctx->priv_data;
 102     int i;
 103
 104     if (s->y < avctx->height - s->font_height) {
 105         s->y += s->font_height;
 106         return;
 107     }
 108
 109     i = 0;
 110     for (; i < avctx->height - s->font_height; i++)
 111         memcpy(s->frame->data[0] + i * s->frame->linesize[0],
 112                s->frame->data[0] + (i + s->font_height) * s->frame->linesize[0],
 113                avctx->width);
 114     for (; i < avctx->height; i++)
 115         memset(s->frame->data[0] + i * s->frame->linesize[0],
 116             DEFAULT_BG_COLOR, avctx->width);
 117 }
 118
 119 static void erase_line(AVCodecContext * avctx, int xoffset, int xlength)
 120 {
 121     AnsiContext *s = avctx->priv_data;
 122     int i;
 123     for (i = 0; i < s->font_height; i++)
 124         memset(s->frame->data[0] + (s->y + i)*s->frame->linesize[0] + xoffset,
 125             DEFAULT_BG_COLOR, xlength);
 126 }
 127
 128 static void erase_screen(AVCodecContext *avctx)
 129 {
 130     AnsiContext *s = avctx->priv_data;
 131     int i;
 132     for (i = 0; i < avctx->height; i++)
 133         memset(s->frame->data[0] + i * s->frame->linesize[0], DEFAULT_BG_COLOR, avctx->width);
 134     s->x = s->y = 0;
 135 }
 136
 137 /**
 138  * Draw character to screen
 139  */
 140 static void draw_char(AVCodecContext *avctx, int c)
 141 {
 142     AnsiContext *s = avctx->priv_data;
 143     int fg = s->fg;
 144     int bg = s->bg;
 145
 146     if ((s->attributes & ATTR_BOLD))
 147         fg += 8;
 148     if ((s->attributes & ATTR_BLINK))
 149         bg += 8;
 150     if ((s->attributes & ATTR_REVERSE))
 151         FFSWAP(int, fg, bg);
 152     if ((s->attributes & ATTR_CONCEALED))
 153         fg = bg;
 154     ff_draw_pc_font(s->frame->data[0] + s->y * s->frame->linesize[0] + s->x,
 155                     s->frame->linesize[0], s->font, s->font_height, c, fg, bg);
 156     s->x += FONT_WIDTH;
 157     if (s->x >= avctx->width) {
 158         s->x = 0;
 159         hscroll(avctx);
 160     }
 161 }
 162
 163 /**
 164  * Execute ANSI escape code
 165  * @return 0 on success, negative on error
 166  */
 167 static int execute_code(AVCodecContext * avctx, int c)
 168 {
 169     AnsiContext *s = avctx->priv_data;
 170     int ret, i;
 171     int width = 0;
 172     int height = 0;
 173
 174     switch(c) {
 175     case 'A': //Cursor Up
 176         s->y = FFMAX(s->y - (s->nb_args > 0 ? s->args[0]*s->font_height : s->font_height), 0);
 177         break;
 178     case 'B': //Cursor Down
 179         s->y = FFMIN(s->y + (s->nb_args > 0 ? s->args[0]*s->font_height : s->font_height), avctx->height - s->font_height);
 180         break;
 181     case 'C': //Cursor Right
 182         s->x = FFMIN(s->x + (s->nb_args > 0 ? s->args[0]*FONT_WIDTH : FONT_WIDTH), avctx->width  - FONT_WIDTH);
 183         break;
 184     case 'D': //Cursor Left
 185         s->x = FFMAX(s->x - (s->nb_args > 0 ? s->args[0]*FONT_WIDTH : FONT_WIDTH), 0);
 186         break;
 187     case 'H': //Cursor Position
 188     case 'f': //Horizontal and Vertical Position
 189         s->y = s->nb_args > 0 ? av_clip((s->args[0] - 1)*s->font_height, 0, avctx->height - s->font_height) : 0;
 190         s->x = s->nb_args > 1 ? av_clip((s->args[1] - 1)*FONT_WIDTH,     0, avctx->width  - FONT_WIDTH) : 0;
 191         break;
 192     case 'h': //set screen mode
 193     case 'l': //reset screen mode
 194         if (s->nb_args < 2)
 195             s->args[0] = DEFAULT_SCREEN_MODE;
 196         switch(s->args[0]) {
 197         case 0: case 1: case 4: case 5: case 13: case 19: //320x200 (25 rows)
 198             s->font = ff_cga_font;
 199             s->font_height = 8;
 200             width  = 40<<3;
 201             height = 25<<3;
 202             break;
 203         case 2: case 3: //640x400 (25 rows)
 204             s->font = ff_vga16_font;
 205             s->font_height = 16;
 206             width  = 80<<3;
 207             height = 25<<4;
 208             break;
 209         case 6: case 14: //640x200 (25 rows)
 210             s->font = ff_cga_font;
 211             s->font_height = 8;
 212             width  = 80<<3;
 213             height = 25<<3;
 214             break;
 215         case 7: //set line wrapping
 216             break;
 217         case 15: case 16: //640x350 (43 rows)
 218             s->font = ff_cga_font;
 219             s->font_height = 8;
 220             width  = 80<<3;
 221             height = 43<<3;
 222             break;
 223         case 17: case 18: //640x480 (60 rows)
 224             s->font = ff_cga_font;
 225             s->font_height = 8;
 226             width  = 80<<3;
 227             height = 60<<4;
 228             break;
 229         default:
 230             avpriv_request_sample(avctx, "Unsupported screen mode");
 231         }
 232         if (width != 0 && height != 0 &&
 233             (width != avctx->width || height != avctx->height)) {
 234             av_frame_unref(s->frame);
 235             ret = ff_set_dimensions(avctx, width, height);
 236             if (ret < 0)
 237                 return ret;
 238             ret = ff_get_buffer(avctx, s->frame, AV_GET_BUFFER_FLAG_REF);
 239             if (ret < 0) {
 240                 av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
 241                 return ret;
 242             }
 243             s->frame->pict_type           = AV_PICTURE_TYPE_I;
 244             s->frame->palette_has_changed = 1;
 245             memcpy(s->frame->data[1], ff_cga_palette, 16 * 4);
 246             erase_screen(avctx);
 247         } else if (c == 'l') {
 248             erase_screen(avctx);
 249         }
 250         break;
 251     case 'J': //Erase in Page
 252         switch (s->args[0]) {
 253         case 0:
 254             erase_line(avctx, s->x, avctx->width - s->x);
 255             if (s->y < avctx->height - s->font_height)
 256                 memset(s->frame->data[0] + (s->y + s->font_height)*s->frame->linesize[0],
 257                     DEFAULT_BG_COLOR, (avctx->height - s->y - s->font_height)*s->frame->linesize[0]);
 258             break;
 259         case 1:
 260             erase_line(avctx, 0, s->x);
 261             if (s->y > 0)
 262                 memset(s->frame->data[0], DEFAULT_BG_COLOR, s->y * s->frame->linesize[0]);
 263             break;
 264         case 2:
 265             erase_screen(avctx);
 266         }
 267         break;
 268     case 'K': //Erase in Line
 269         switch(s->args[0]) {
 270         case 0:
 271             erase_line(avctx, s->x, avctx->width - s->x);
 272             break;
 273         case 1:
 274             erase_line(avctx, 0, s->x);
 275             break;
 276         case 2:
 277             erase_line(avctx, 0, avctx->width);
 278         }
 279         break;
 280     case 'm': //Select Graphics Rendition
 281         if (s->nb_args == 0) {
 282             s->nb_args = 1;
 283             s->args[0] = 0;
 284         }
 285         for (i = 0; i < FFMIN(s->nb_args, MAX_NB_ARGS); i++) {
 286             int m = s->args[i];
 287             if (m == 0) {
 288                 s->attributes = 0;
 289                 s->fg = DEFAULT_FG_COLOR;
 290                 s->bg = DEFAULT_BG_COLOR;
 291             } else if (m == 1 || m == 2 || m == 4 || m == 5 || m == 7 || m == 8) {
 292                 s->attributes |= 1 << (m - 1);
 293             } else if (m >= 30 && m <= 38) {
 294                 s->fg = ansi_to_cga[m - 30];
 295             } else if (m == 39) {
 296                 s->fg = ansi_to_cga[DEFAULT_FG_COLOR];
 297             } else if (m >= 40 && m <= 47) {
 298                 s->bg = ansi_to_cga[m - 40];
 299             } else if (m == 49) {
 300                 s->fg = ansi_to_cga[DEFAULT_BG_COLOR];
 301             } else {
 302                 avpriv_request_sample(avctx, "Unsupported rendition parameter");
 303             }
 304         }
 305         break;
 306     case 'n': //Device Status Report
 307     case 'R': //report current line and column
 308         /* ignore */
 309         break;
 310     case 's': //Save Cursor Position
 311         s->sx = s->x;
 312         s->sy = s->y;
 313         break;
 314     case 'u': //Restore Cursor Position
 315         s->x = av_clip(s->sx, 0, avctx->width  - FONT_WIDTH);
 316         s->y = av_clip(s->sy, 0, avctx->height - s->font_height);
 317         break;
 318     default:
 319         avpriv_request_sample(avctx, "Unknown escape code");
 320         break;
 321     }
 322     return 0;
 323 }
 324
 325 static int decode_frame(AVCodecContext *avctx,
 326                             void *data, int *got_frame,
 327                             AVPacket *avpkt)
 328 {
 329     AnsiContext *s = avctx->priv_data;
 330     uint8_t *buf = avpkt->data;
 331     int buf_size = avpkt->size;
 332     const uint8_t *buf_end   = buf+buf_size;
 333     int ret, i, count;
 334
 335     ret = ff_reget_buffer(avctx, s->frame);
 336     if (ret < 0){
 337         av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
 338         return ret;
 339     }
 340     if (!avctx->frame_number) {
 341         memset(s->frame->data[0], 0, avctx->height * FFABS(s->frame->linesize[0]));
 342         memset(s->frame->data[1], 0, AVPALETTE_SIZE);
 343     }
 344
 345     s->frame->pict_type           = AV_PICTURE_TYPE_I;
 346     s->frame->palette_has_changed = 1;
 347     memcpy(s->frame->data[1], ff_cga_palette, 16 * 4);
 348
 349     while(buf < buf_end) {
 350         switch(s->state) {
 351         case STATE_NORMAL:
 352             switch (buf[0]) {
 353             case 0x00: //NUL
 354             case 0x07: //BEL
 355             case 0x1A: //SUB
 356                 /* ignore */
 357                 break;
 358             case 0x08: //BS
 359                 s->x = FFMAX(s->x - 1, 0);
 360                 break;
 361             case 0x09: //HT
 362                 i = s->x / FONT_WIDTH;
 363                 count = ((i + 8) & ~7) - i;
 364                 for (i = 0; i < count; i++)
 365                     draw_char(avctx, ' ');
 366                 break;
 367             case 0x0A: //LF
 368                 hscroll(avctx);
 369             case 0x0D: //CR
 370                 s->x = 0;
 371                 break;
 372             case 0x0C: //FF
 373                 erase_screen(avctx);
 374                 break;
 375             case 0x1B: //ESC
 376                 s->state = STATE_ESCAPE;
 377                 break;
 378             default:
 379                 draw_char(avctx, buf[0]);
 380             }
 381             break;
 382         case STATE_ESCAPE:
 383             if (buf[0] == '[') {
 384                 s->state   = STATE_CODE;
 385                 s->nb_args = 0;
 386                 s->args[0] = 0;
 387             } else {
 388                 s->state = STATE_NORMAL;
 389                 draw_char(avctx, 0x1B);
 390                 continue;
 391             }
 392             break;
 393         case STATE_CODE:
 394             switch(buf[0]) {
 395             case '0': case '1': case '2': case '3': case '4':
 396             case '5': case '6': case '7': case '8': case '9':
 397                 if (s->nb_args < MAX_NB_ARGS)
 398                     s->args[s->nb_args] = s->args[s->nb_args] * 10 + buf[0] - '0';
 399                 break;
 400             case ';':
 401                 s->nb_args++;
 402                 if (s->nb_args < MAX_NB_ARGS)
 403                     s->args[s->nb_args] = 0;
 404                 break;
 405             case 'M':
 406                 s->state = STATE_MUSIC_PREAMBLE;
 407                 break;
 408             case '=': case '?':
 409                 /* ignore */
 410                 break;
 411             default:
 412                 if (s->nb_args > MAX_NB_ARGS)
 413                     av_log(avctx, AV_LOG_WARNING, "args overflow (%i)\n", s->nb_args);
 414                 if (s->nb_args < MAX_NB_ARGS && s->args[s->nb_args])
 415                     s->nb_args++;
 416                 if ((ret = execute_code(avctx, buf[0])) < 0)
 417                     return ret;
 418                 s->state = STATE_NORMAL;
 419             }
 420             break;
 421         case STATE_MUSIC_PREAMBLE:
 422             if (buf[0] == 0x0E || buf[0] == 0x1B)
 423                 s->state = STATE_NORMAL;
 424             /* ignore music data */
 425             break;
 426         }
 427         buf++;
 428     }
 429
 430     *got_frame = 1;
 431     if ((ret = av_frame_ref(data, s->frame)) < 0)
 432         return ret;
 433     return buf_size;
 434 }
 435
 436 static av_cold int decode_close(AVCodecContext *avctx)
 437 {
 438     AnsiContext *s = avctx->priv_data;
 439
 440     av_frame_free(&s->frame);
 441     return 0;
 442 }
 443
 444 AVCodec ff_ansi_decoder = {
 445     .name           = "ansi",
 446     .long_name      = NULL_IF_CONFIG_SMALL("ASCII/ANSI art"),
 447     .type           = AVMEDIA_TYPE_VIDEO,
 448     .id             = AV_CODEC_ID_ANSI,
 449     .priv_data_size = sizeof(AnsiContext),
 450     .init           = decode_init,
 451     .close          = decode_close,
 452     .decode         = decode_frame,
 453     .capabilities   = AV_CODEC_CAP_DR1,
 454     .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE,
 455 };