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1 /*
2  * SubRip subtitle decoder
3  * Copyright (c) 2010  Aurelien Jacobs <aurel@gnuage.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 #include "libavutil/avstring.h"
23 #include "libavutil/parseutils.h"
24 #include "avcodec.h"
25 #include "ass.h"
26
27 static int html_color_parse(AVCodecContext *avctx, const char *str)
28 {
29     uint8_t rgba[4];
30     if (av_parse_color(rgba, str, strcspn(str, "\" >"), avctx) < 0)
31         return -1;
32     return rgba[0] | rgba[1] << 8 | rgba[2] << 16;
33 }
34
35 enum {
36     PARAM_UNKNOWN = -1,
37     PARAM_SIZE,
38     PARAM_COLOR,
39     PARAM_FACE,
40     PARAM_NUMBER
41 };
42
43 typedef struct {
44     char tag[128];
45     char param[PARAM_NUMBER][128];
46 } SrtStack;
47
48 static const char *srt_to_ass(AVCodecContext *avctx, char *out, char *out_end,
49                               const char *in, int x1, int y1, int x2, int y2)
50 {
51     char c, *param, buffer[128], tmp[128];
52     int len, tag_close, sptr = 1, line_start = 1, an = 0, end = 0;
53     SrtStack stack[16];
54
55     stack[0].tag[0] = 0;
56     strcpy(stack[0].param[PARAM_SIZE],  "{\\fs}");
57     strcpy(stack[0].param[PARAM_COLOR], "{\\c}");
58     strcpy(stack[0].param[PARAM_FACE],  "{\\fn}");
59
60     if (x1 >= 0 && y1 >= 0) {
61         if (x2 >= 0 && y2 >= 0 && (x2 != x1 || y2 != y1))
62             out += snprintf(out, out_end-out,
63                             "{\\an1}{\\move(%d,%d,%d,%d)}", x1, y1, x2, y2);
64         else
65             out += snprintf(out, out_end-out, "{\\an1}{\\pos(%d,%d)}", x1, y1);
66     }
67
68     for (; out < out_end && !end && *in; in++) {
69         switch (*in) {
70         case '\r':
71             break;
72         case '\n':
73             if (line_start) {
74                 end = 1;
75                 break;
76             }
77             while (out[-1] == ' ')
78                 out--;
79             out += snprintf(out, out_end-out, "\\N");
80             line_start = 1;
81             break;
82         case ' ':
83             if (!line_start)
84                 *out++ = *in;
85             break;
86         case '{':    /* skip all {\xxx} substrings except for {\an%d}
87                         and all microdvd like styles such as {Y:xxx} */
88             an += sscanf(in, "{\\an%*1u}%c", &c) == 1;
89             if ((an != 1 && sscanf(in, "{\\%*[^}]}%n%c", &len, &c) > 0) ||
90                 sscanf(in, "{%*1[CcFfoPSsYy]:%*[^}]}%n%c", &len, &c) > 0) {
91                 in += len - 1;
92             } else
93                 *out++ = *in;
94             break;
95         case '<':
96             tag_close = in[1] == '/';
97             if (sscanf(in+tag_close+1, "%127[^>]>%n%c", buffer, &len,&c) >= 2) {
98                 if ((param = strchr(buffer, ' ')))
99                     *param++ = 0;
100                 if ((!tag_close && sptr < FF_ARRAY_ELEMS(stack)) ||
101                     ( tag_close && sptr > 0 && !strcmp(stack[sptr-1].tag, buffer))) {
102                     int i, j, unknown = 0;
103                     in += len + tag_close;
104                     if (!tag_close)
105                         memset(stack+sptr, 0, sizeof(*stack));
106                     if (!strcmp(buffer, "font")) {
107                         if (tag_close) {
108                             for (i=PARAM_NUMBER-1; i>=0; i--)
109                                 if (stack[sptr-1].param[i][0])
110                                     for (j=sptr-2; j>=0; j--)
111                                         if (stack[j].param[i][0]) {
112                                             out += snprintf(out, out_end-out,
113                                                             "%s", stack[j].param[i]);
114                                             break;
115                                         }
116                         } else {
117                             while (param) {
118                                 if (!strncmp(param, "size=", 5)) {
119                                     unsigned font_size;
120                                     param += 5 + (param[5] == '"');
121                                     if (sscanf(param, "%u", &font_size) == 1) {
122                                         snprintf(stack[sptr].param[PARAM_SIZE],
123                                              sizeof(stack[0].param[PARAM_SIZE]),
124                                              "{\\fs%u}", font_size);
125                                     }
126                                 } else if (!strncmp(param, "color=", 6)) {
127                                     param += 6 + (param[6] == '"');
128                                     snprintf(stack[sptr].param[PARAM_COLOR],
129                                          sizeof(stack[0].param[PARAM_COLOR]),
130                                          "{\\c&H%X&}",
131                                          html_color_parse(avctx, param));
132                                 } else if (!strncmp(param, "face=", 5)) {
133                                     param += 5 + (param[5] == '"');
134                                     len = strcspn(param,
135                                                   param[-1] == '"' ? "\"" :" ");
136                                     av_strlcpy(tmp, param,
137                                                FFMIN(sizeof(tmp), len+1));
138                                     param += len;
139                                     snprintf(stack[sptr].param[PARAM_FACE],
140                                              sizeof(stack[0].param[PARAM_FACE]),
141                                              "{\\fn%s}", tmp);
142                                 }
143                                 if ((param = strchr(param, ' ')))
144                                     param++;
145                             }
146                             for (i=0; i<PARAM_NUMBER; i++)
147                                 if (stack[sptr].param[i][0])
148                                     out += snprintf(out, out_end-out,
149                                                     "%s", stack[sptr].param[i]);
150                         }
151                     } else if (!buffer[1] && strspn(buffer, "bisu") == 1) {
152                         out += snprintf(out, out_end-out,
153                                         "{\\%c%d}", buffer[0], !tag_close);
154                     } else {
155                         unknown = 1;
156                         snprintf(tmp, sizeof(tmp), "</%s>", buffer);
157                     }
158                     if (tag_close) {
159                         sptr--;
160                     } else if (unknown && !strstr(in, tmp)) {
161                         in -= len + tag_close;
162                         *out++ = *in;
163                     } else
164                         av_strlcpy(stack[sptr++].tag, buffer,
165                                    sizeof(stack[0].tag));
166                     break;
167                 }
168             }
169         default:
170             *out++ = *in;
171             break;
172         }
173         if (*in != ' ' && *in != '\r' && *in != '\n')
174             line_start = 0;
175     }
176
177     out = FFMIN(out, out_end-3);
178     while (!strncmp(out-2, "\\N", 2))
179         out -= 2;
180     while (out[-1] == ' ')
181         out--;
182     out += snprintf(out, out_end-out, "\r\n");
183     return in;
184 }
185
186 static const char *read_ts(const char *buf, int *ts_start, int *ts_end,
187                            int *x1, int *y1, int *x2, int *y2)
188 {
189     int i, hs, ms, ss, he, me, se;
190
191     for (i=0; i<2; i++) {
192         /* try to read timestamps in either the first or second line */
193         int c = sscanf(buf, "%d:%2d:%2d%*1[,.]%3d --> %d:%2d:%2d%*1[,.]%3d"
194                        "%*[ ]X1:%u X2:%u Y1:%u Y2:%u",
195                        &hs, &ms, &ss, ts_start, &he, &me, &se, ts_end,
196                        x1, x2, y1, y2);
197         buf += strcspn(buf, "\n") + 1;
198         if (c >= 8) {
199             *ts_start = 100*(ss + 60*(ms + 60*hs)) + *ts_start/10;
200             *ts_end   = 100*(se + 60*(me + 60*he)) + *ts_end  /10;
201             return buf;
202         }
203     }
204     return NULL;
205 }
206
207 static int srt_decode_frame(AVCodecContext *avctx,
208                             void *data, int *got_sub_ptr, AVPacket *avpkt)
209 {
210     AVSubtitle *sub = data;
211     int ts_start, ts_end, x1 = -1, y1 = -1, x2 = -1, y2 = -1;
212     char buffer[2048];
213     const char *ptr = avpkt->data;
214     const char *end = avpkt->data + avpkt->size;
215
216     if (avpkt->size <= 0)
217         return avpkt->size;
218
219     ff_ass_init(sub);
220
221     while (ptr < end && *ptr) {
222         ptr = read_ts(ptr, &ts_start, &ts_end, &x1, &y1, &x2, &y2);
223         if (!ptr)
224             break;
225         ptr = srt_to_ass(avctx, buffer, buffer+sizeof(buffer), ptr,
226                          x1, y1, x2, y2);
227         ff_ass_add_rect(sub, buffer, ts_start, ts_end, 0);
228     }
229
230     *got_sub_ptr = sub->num_rects > 0;
231     return avpkt->size;
232 }
233
234 AVCodec ff_srt_decoder = {
235     .name         = "srt",
236     .long_name    = NULL_IF_CONFIG_SMALL("SubRip subtitle"),
237     .type         = AVMEDIA_TYPE_SUBTITLE,
238     .id           = CODEC_ID_SRT,
239     .init         = ff_ass_subtitle_header_default,
240     .decode       = srt_decode_frame,
241 };