src/ssa_reader.cc

   1 /*
   2     Copyright (C) 2016-2019 Carl Hetherington <cth@carlh.net>
   3
   4     This program is free software; you can redistribute it and/or modify
   5     it under the terms of the GNU General Public License as published by
   6     the Free Software Foundation; either version 2 of the License, or
   7     (at your option) any later version.
   8
   9     This program is distributed in the hope that it will be useful,
  10     but WITHOUT ANY WARRANTY; without even the implied warranty of
  11     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12     GNU General Public License for more details.
  13
  14     You should have received a copy of the GNU General Public License
  15     along with this program; if not, write to the Free Software
  16     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  17
  18 */
  19
  20 #include "ssa_reader.h"
  21 #include "util.h"
  22 #include "sub_assert.h"
  23 #include "raw_convert.h"
  24 #include "subtitle.h"
  25 #include "compose.hpp"
  26 #include <boost/algorithm/string.hpp>
  27 #include <boost/bind.hpp>
  28 #include <boost/foreach.hpp>
  29 #include <iostream>
  30 #include <vector>
  31
  32 using std::string;
  33 using std::vector;
  34 using std::map;
  35 using std::cout;
  36 using std::list;
  37 using boost::optional;
  38 using boost::function;
  39 using namespace boost::algorithm;
  40 using namespace sub;
  41
  42 /** @param s Subtitle string encoded in UTF-8 */
  43 SSAReader::SSAReader (string s)
  44 {
  45         this->read (boost::bind(&get_line_string, &s));
  46 }
  47
  48 /** @param f Subtitle file encoded in UTF-8 */
  49 SSAReader::SSAReader (FILE* f)
  50 {
  51         this->read (boost::bind (&get_line_file, f));
  52 }
  53
  54 Colour
  55 h_colour (string s)
  56 {
  57         /* There are both BGR and ABGR versions of these colours */
  58         if ((s.length() != 8 && s.length() != 10) || s[0] != '&' || s[1] != 'H') {
  59                 throw SSAError(String::compose("Badly formatted colour tag %1", s));
  60         }
  61         int ir, ig, ib;
  62         /* XXX: ignoring alpha channel here; note that 00 is opaque and FF is transparent */
  63         int const off = s.length() == 10 ? 4 : 2;
  64         if (sscanf(s.c_str() + off, "%2x%2x%2x", &ib, &ig, &ir) < 3) {
  65                 throw SSAError(String::compose("Badly formatted colour tag %1", s));
  66         }
  67         return sub::Colour(ir / 255.0, ig / 255.0, ib / 255.0);
  68 }
  69
  70 class Style
  71 {
  72 public:
  73         Style ()
  74                 : font_size (72)
  75                 , primary_colour (255, 255, 255)
  76                 , bold (false)
  77                 , italic (false)
  78                 , underline (false)
  79                 , horizontal_reference (HORIZONTAL_CENTRE_OF_SCREEN)
  80                 , vertical_reference (BOTTOM_OF_SCREEN)
  81                 , vertical_margin (0)
  82         {}
  83
  84         Style (string format_line, string style_line)
  85                 : font_size (72)
  86                 , primary_colour (255, 255, 255)
  87                 , bold (false)
  88                 , italic (false)
  89                 , underline (false)
  90                 , horizontal_reference (HORIZONTAL_CENTRE_OF_SCREEN)
  91                 , vertical_reference (BOTTOM_OF_SCREEN)
  92                 , vertical_margin (0)
  93         {
  94                 vector<string> keys;
  95                 split (keys, format_line, boost::is_any_of (","));
  96                 vector<string> style;
  97                 split (style, style_line, boost::is_any_of (","));
  98
  99                 SUB_ASSERT (!keys.empty());
 100                 SUB_ASSERT (!style.empty());
 101                 SUB_ASSERT (keys.size() == style.size());
 102
 103                 for (size_t i = 0; i < style.size(); ++i) {
 104                         trim (keys[i]);
 105                         trim (style[i]);
 106                         if (keys[i] == "Name") {
 107                                 name = style[i];
 108                         } else if (keys[i] == "Fontname") {
 109                                 font_name = style[i];
 110                         } else if (keys[i] == "Fontsize") {
 111                                 font_size = raw_convert<int> (style[i]);
 112                         } else if (keys[i] == "PrimaryColour") {
 113                                 primary_colour = colour (style[i]);
 114                         } else if (keys[i] == "BackColour") {
 115                                 back_colour = colour (style[i]);
 116                         } else if (keys[i] == "Bold") {
 117                                 bold = style[i] == "-1";
 118                         } else if (keys[i] == "Italic") {
 119                                 italic = style[i] == "-1";
 120                         } else if (keys[i] == "Underline") {
 121                                 underline = style[i] == "-1";
 122                         } else if (keys[i] == "BorderStyle") {
 123                                 if (style[i] == "1") {
 124                                         effect = SHADOW;
 125                                 }
 126                         } else if (keys[i] == "Alignment") {
 127                                 /* These values from libass' source code */
 128                                 switch ((raw_convert<int> (style[i]) - 1) % 3) {
 129                                 case 0:
 130                                         horizontal_reference = LEFT_OF_SCREEN;
 131                                         break;
 132                                 case 1:
 133                                         horizontal_reference = HORIZONTAL_CENTRE_OF_SCREEN;
 134                                         break;
 135                                 case 2:
 136                                         horizontal_reference = RIGHT_OF_SCREEN;
 137                                         break;
 138                                 }
 139                                 switch (raw_convert<int> (style[i]) & 12) {
 140                                 case 4:
 141                                         vertical_reference = TOP_OF_SCREEN;
 142                                         break;
 143                                 case 8:
 144                                         vertical_reference = VERTICAL_CENTRE_OF_SCREEN;
 145                                         break;
 146                                 case 0:
 147                                         vertical_reference = BOTTOM_OF_SCREEN;
 148                                         break;
 149                                 }
 150                         } else if (keys[i] == "MarginV") {
 151                                 vertical_margin = raw_convert<int> (style[i]);
 152                         }
 153                 }
 154         }
 155
 156         string name;
 157         optional<string> font_name;
 158         int font_size;
 159         Colour primary_colour;
 160         /** outline colour */
 161         optional<Colour> back_colour;
 162         bool bold;
 163         bool italic;
 164         bool underline;
 165         optional<Effect> effect;
 166         HorizontalReference horizontal_reference;
 167         VerticalReference vertical_reference;
 168         int vertical_margin;
 169
 170 private:
 171         Colour colour (string c) const
 172         {
 173                 if (c.length() > 0 && c[0] == '&') {
 174                         /* &Hbbggrr or &Haabbggrr */
 175                         return h_colour (c);
 176                 } else {
 177                         /* integer */
 178                         int i = raw_convert<int>(c);
 179                         return Colour (
 180                                 ((i & 0x0000ff) >>  0) / 255.0,
 181                                 ((i & 0x00ff00) >>  8) / 255.0,
 182                                 ((i & 0xff0000) >> 16) / 255.0
 183                                 );
 184                 }
 185         }
 186 };
 187
 188 Time
 189 SSAReader::parse_time (string t) const
 190 {
 191         vector<string> bits;
 192         split (bits, t, is_any_of (":."));
 193         SUB_ASSERT (bits.size() == 4);
 194         return Time::from_hms (
 195                 raw_convert<int> (bits[0]),
 196                 raw_convert<int> (bits[1]),
 197                 raw_convert<int> (bits[2]),
 198                 raw_convert<int> (bits[3]) * 10
 199                 );
 200 }
 201
 202 void
 203 SSAReader::parse_style (RawSubtitle& sub, string style, int play_res_x, int play_res_y)
 204 {
 205         if (style == "\\i1") {
 206                 sub.italic = true;
 207         } else if (style == "\\i0" || style == "\\i") {
 208                 sub.italic = false;
 209         } else if (style == "\\b1") {
 210                 sub.bold = true;
 211         } else if (style == "\\b0") {
 212                 sub.bold = false;
 213         } else if (style == "\\u1") {
 214                 sub.underline = true;
 215         } else if (style == "\\u0") {
 216                 sub.underline = false;
 217         } else if (style == "\\an1") {
 218                 sub.horizontal_position.reference = sub::LEFT_OF_SCREEN;
 219                 sub.vertical_position.reference = sub::BOTTOM_OF_SCREEN;
 220         } else if (style == "\\an2") {
 221                 sub.horizontal_position.reference = sub::HORIZONTAL_CENTRE_OF_SCREEN;
 222                 sub.vertical_position.reference = sub::BOTTOM_OF_SCREEN;
 223         } else if (style == "\\an3") {
 224                 sub.horizontal_position.reference = sub::RIGHT_OF_SCREEN;
 225                 sub.vertical_position.reference = sub::BOTTOM_OF_SCREEN;
 226         } else if (style == "\\an4") {
 227                 sub.horizontal_position.reference = sub::LEFT_OF_SCREEN;
 228                 sub.vertical_position.reference = sub::VERTICAL_CENTRE_OF_SCREEN;
 229         } else if (style == "\\an5") {
 230                 sub.horizontal_position.reference = sub::HORIZONTAL_CENTRE_OF_SCREEN;
 231                 sub.vertical_position.reference = sub::VERTICAL_CENTRE_OF_SCREEN;
 232         } else if (style == "\\an6") {
 233                 sub.horizontal_position.reference = sub::RIGHT_OF_SCREEN;
 234                 sub.vertical_position.reference = sub::VERTICAL_CENTRE_OF_SCREEN;
 235         } else if (style == "\\an7") {
 236                 sub.horizontal_position.reference = sub::LEFT_OF_SCREEN;
 237                 sub.vertical_position.reference = sub::TOP_OF_SCREEN;
 238         } else if (style == "\\an8") {
 239                 sub.horizontal_position.reference = sub::HORIZONTAL_CENTRE_OF_SCREEN;
 240                 sub.vertical_position.reference = sub::TOP_OF_SCREEN;
 241         } else if (style == "\\an9") {
 242                 sub.horizontal_position.reference = sub::RIGHT_OF_SCREEN;
 243                 sub.vertical_position.reference = sub::TOP_OF_SCREEN;
 244         } else if (boost::starts_with(style, "\\pos")) {
 245                 vector<string> bits;
 246                 boost::algorithm::split (bits, style, boost::is_any_of("(,"));
 247                 SUB_ASSERT (bits.size() == 3);
 248                 sub.horizontal_position.reference = sub::LEFT_OF_SCREEN;
 249                 sub.horizontal_position.proportional = raw_convert<float>(bits[1]) / play_res_x;
 250                 sub.vertical_position.reference = sub::TOP_OF_SCREEN;
 251                 sub.vertical_position.proportional = raw_convert<float>(bits[2]) / play_res_y;
 252         } else if (boost::starts_with(style, "\\fs")) {
 253                 SUB_ASSERT (style.length() > 3);
 254                 sub.font_size.set_points (raw_convert<int>(style.substr(3)));
 255         } else if (boost::starts_with(style, "\\c")) {
 256                 /* \c&Hbbggrr& */
 257                 if (style.length() <= 2) {
 258                         throw SSAError(String::compose("Badly formatted colour tag %1", style));
 259                 }
 260                 sub.colour = h_colour (style.substr(2, style.length() - 3));
 261         }
 262 }
 263
 264 /** @param base RawSubtitle filled in with any required common values.
 265  *  @param line SSA line string (i.e. just the subtitle, possibly with embedded stuff)
 266  *  @return List of RawSubtitles to represent line with vertical reference TOP_OF_SUBTITLE.
 267  */
 268 list<RawSubtitle>
 269 SSAReader::parse_line (RawSubtitle base, string line, int play_res_x, int play_res_y)
 270 {
 271         enum {
 272                 TEXT,
 273                 STYLE,
 274                 BACKSLASH
 275         } state = TEXT;
 276
 277         list<RawSubtitle> subs;
 278         RawSubtitle current = base;
 279         string style;
 280
 281         if (!current.vertical_position.reference) {
 282                 current.vertical_position.reference = BOTTOM_OF_SCREEN;
 283         }
 284
 285         if (!current.vertical_position.proportional) {
 286                 current.vertical_position.proportional = 0;
 287         }
 288
 289         /* We must have a font size, as there could be a margin specified
 290            in pixels and in that case we must know how big the subtitle
 291            lines are to work out the position on screen.
 292         */
 293         if (!current.font_size.points()) {
 294                 current.font_size.set_points (72);
 295         }
 296
 297         /* Count the number of line breaks */
 298         int line_breaks = 0;
 299         if (line.length() > 0) {
 300                 for (size_t i = 0; i < line.length() - 1; ++i) {
 301                         if (line[i] == '\\' && (line[i+1] == 'n' || line[i+1] == 'N')) {
 302                                 ++line_breaks;
 303                         }
 304                 }
 305         }
 306
 307         /* Imagine that the screen is 792 points (i.e. 11 inches) high (as with DCP) */
 308         double const line_size = current.font_size.proportional(792) * 1.2;
 309
 310         /* Tweak vertical_position accordingly */
 311         switch (current.vertical_position.reference.get()) {
 312         case TOP_OF_SCREEN:
 313         case TOP_OF_SUBTITLE:
 314                 /* Nothing to do */
 315                 break;
 316         case VERTICAL_CENTRE_OF_SCREEN:
 317                 current.vertical_position.proportional = current.vertical_position.proportional.get() - ((line_breaks + 1) * line_size) / 2;
 318                 break;
 319         case BOTTOM_OF_SCREEN:
 320                 current.vertical_position.proportional = current.vertical_position.proportional.get() + line_breaks * line_size;
 321                 break;
 322         }
 323
 324         for (size_t i = 0; i < line.length(); ++i) {
 325                 char const c = line[i];
 326                 switch (state) {
 327                 case TEXT:
 328                         if (c == '{') {
 329                                 state = STYLE;
 330                         } else if (c == '\\') {
 331                                 state = BACKSLASH;
 332                         } else if (c != '\r' && c != '\n') {
 333                                 current.text += c;
 334                         }
 335                         break;
 336                 case STYLE:
 337                         if (c == '}' || c == '\\') {
 338                                 if (!current.text.empty ()) {
 339                                         subs.push_back (current);
 340                                         current.text = "";
 341                                 }
 342                                 parse_style (current, style, play_res_x, play_res_y);
 343                                 style = "";
 344                         }
 345
 346                         if (c == '}') {
 347                                 state = TEXT;
 348                         } else {
 349                                 style += c;
 350                         }
 351                         break;
 352                 case BACKSLASH:
 353                         if (c == 'n' || c == 'N') {
 354                                 if (!current.text.empty ()) {
 355                                         subs.push_back (current);
 356                                         current.text = "";
 357                                 }
 358                                 /* Move down one line (1.2 times the font size) */
 359                                 if (current.vertical_position.reference.get() == BOTTOM_OF_SCREEN) {
 360                                         current.vertical_position.proportional = current.vertical_position.proportional.get() - line_size;
 361                                 } else {
 362                                         current.vertical_position.proportional = current.vertical_position.proportional.get() + line_size;
 363                                 }
 364                         }
 365                         state = TEXT;
 366                         break;
 367                 }
 368         }
 369
 370         if (!current.text.empty ()) {
 371                 subs.push_back (current);
 372         }
 373
 374         return subs;
 375 }
 376
 377 void
 378 SSAReader::read (function<optional<string> ()> get_line)
 379 {
 380         enum {
 381                 INFO,
 382                 STYLES,
 383                 EVENTS
 384         } part = INFO;
 385
 386         int play_res_x = 288;
 387         int play_res_y = 288;
 388         map<string, Style> styles;
 389         string style_format_line;
 390         vector<string> event_format;
 391
 392         while (true) {
 393                 optional<string> line = get_line ();
 394                 if (!line) {
 395                         break;
 396                 }
 397
 398                 trim (*line);
 399                 remove_unicode_bom (line);
 400
 401                 if (starts_with (*line, ";") || line->empty ()) {
 402                         continue;
 403                 }
 404
 405                 if (starts_with (*line, "[")) {
 406                         /* Section heading */
 407                         if (line.get() == "[Script Info]") {
 408                                 part = INFO;
 409                         } else if (line.get() == "[V4 Styles]" || line.get() == "[V4+ Styles]") {
 410                                 part = STYLES;
 411                         } else if (line.get() == "[Events]") {
 412                                 part = EVENTS;
 413                         }
 414                         continue;
 415                 }
 416
 417                 size_t const colon = line->find (":");
 418                 SUB_ASSERT (colon != string::npos);
 419                 string const type = line->substr (0, colon);
 420                 string body = line->substr (colon + 1);
 421                 trim (body);
 422
 423                 switch (part) {
 424                 case INFO:
 425                         if (type == "PlayResX") {
 426                                 play_res_x = raw_convert<int> (body);
 427                         } else if (type == "PlayResY") {
 428                                 play_res_y = raw_convert<int> (body);
 429                         }
 430                         break;
 431                 case STYLES:
 432                         if (type == "Format") {
 433                                 style_format_line = body;
 434                         } else if (type == "Style") {
 435                                 SUB_ASSERT (!style_format_line.empty ());
 436                                 Style s (style_format_line, body);
 437                                 styles[s.name] = s;
 438                         }
 439                         break;
 440                 case EVENTS:
 441                         if (type == "Format") {
 442                                 split (event_format, body, is_any_of (","));
 443                                 BOOST_FOREACH (string& i, event_format) {
 444                                         trim (i);
 445                                 }
 446                         } else if (type == "Dialogue") {
 447                                 SUB_ASSERT (!event_format.empty ());
 448                                 vector<string> event;
 449                                 split (event, body, is_any_of (","));
 450
 451                                 /* There may be commas in the subtitle part; reassemble any extra parts
 452                                    from when we just split it.
 453                                 */
 454                                 while (event.size() > event_format.size()) {
 455                                         string const ex = event.back ();
 456                                         event.pop_back ();
 457                                         event.back() += "," + ex;
 458                                 }
 459
 460                                 SUB_ASSERT (!event.empty());
 461                                 SUB_ASSERT (event_format.size() == event.size());
 462
 463                                 RawSubtitle sub;
 464
 465                                 for (size_t i = 0; i < event.size(); ++i) {
 466                                         trim (event[i]);
 467                                         if (event_format[i] == "Start") {
 468                                                 sub.from = parse_time (event[i]);
 469                                         } else if (event_format[i] == "End") {
 470                                                 sub.to = parse_time (event[i]);
 471                                         } else if (event_format[i] == "Style") {
 472                                                 /* libass trims leading '*'s from style names, commenting that
 473                                                    "they seem to mean literally nothing".  Go figure...
 474                                                 */
 475                                                 trim_left_if (event[i], boost::is_any_of ("*"));
 476                                                 SUB_ASSERT (styles.find(event[i]) != styles.end());
 477                                                 Style style = styles[event[i]];
 478                                                 sub.font = style.font_name;
 479                                                 sub.font_size = FontSize::from_points (style.font_size);
 480                                                 sub.colour = style.primary_colour;
 481                                                 sub.effect_colour = style.back_colour;
 482                                                 sub.bold = style.bold;
 483                                                 sub.italic = style.italic;
 484                                                 sub.underline = style.underline;
 485                                                 sub.effect = style.effect;
 486                                                 sub.horizontal_position.reference = style.horizontal_reference;
 487                                                 sub.vertical_position.reference = style.vertical_reference;
 488                                                 sub.vertical_position.proportional = float(style.vertical_margin) / play_res_y;
 489                                         } else if (event_format[i] == "MarginV") {
 490                                                 sub.vertical_position.proportional = raw_convert<float>(event[i]) / play_res_y;
 491                                         } else if (event_format[i] == "Text") {
 492                                                 BOOST_FOREACH (sub::RawSubtitle j, parse_line (sub, event[i], play_res_x, play_res_y)) {
 493                                                         _subs.push_back (j);
 494                                                 }
 495                                         }
 496                                 }
 497                         }
 498                 }
 499
 500         }
 501 }