Libav 0.7.1
libavcodec/srtdec.c
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00001 /*
00002  * SubRip subtitle decoder
00003  * Copyright (c) 2010  Aurelien Jacobs <aurel@gnuage.org>
00004  *
00005  * This file is part of Libav.
00006  *
00007  * Libav is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Lesser General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2.1 of the License, or (at your option) any later version.
00011  *
00012  * Libav is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Lesser General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Lesser General Public
00018  * License along with Libav; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 
00022 #include "libavutil/avstring.h"
00023 #include "libavutil/parseutils.h"
00024 #include "avcodec.h"
00025 #include "ass.h"
00026 
00027 static int html_color_parse(AVCodecContext *avctx, const char *str)
00028 {
00029     uint8_t rgba[4];
00030     if (av_parse_color(rgba, str, strcspn(str, "\" >"), avctx) < 0)
00031         return -1;
00032     return rgba[0] | rgba[1] << 8 | rgba[2] << 16;
00033 }
00034 
00035 enum {
00036     PARAM_UNKNOWN = -1,
00037     PARAM_SIZE,
00038     PARAM_COLOR,
00039     PARAM_FACE,
00040     PARAM_NUMBER
00041 };
00042 
00043 typedef struct {
00044     char tag[128];
00045     char param[PARAM_NUMBER][128];
00046 } SrtStack;
00047 
00048 static const char *srt_to_ass(AVCodecContext *avctx, char *out, char *out_end,
00049                               const char *in, int x1, int y1, int x2, int y2)
00050 {
00051     char c, *param, buffer[128], tmp[128];
00052     int len, tag_close, sptr = 1, line_start = 1, an = 0, end = 0;
00053     SrtStack stack[16];
00054 
00055     stack[0].tag[0] = 0;
00056     strcpy(stack[0].param[PARAM_SIZE],  "{\\fs}");
00057     strcpy(stack[0].param[PARAM_COLOR], "{\\c}");
00058     strcpy(stack[0].param[PARAM_FACE],  "{\\fn}");
00059 
00060     if (x1 >= 0 && y1 >= 0) {
00061         if (x2 >= 0 && y2 >= 0 && (x2 != x1 || y2 != y1))
00062             out += snprintf(out, out_end-out,
00063                             "{\\an1}{\\move(%d,%d,%d,%d)}", x1, y1, x2, y2);
00064         else
00065             out += snprintf(out, out_end-out, "{\\an1}{\\pos(%d,%d)}", x1, y1);
00066     }
00067 
00068     for (; out < out_end && !end && *in; in++) {
00069         switch (*in) {
00070         case '\r':
00071             break;
00072         case '\n':
00073             if (line_start) {
00074                 end = 1;
00075                 break;
00076             }
00077             while (out[-1] == ' ')
00078                 out--;
00079             out += snprintf(out, out_end-out, "\\N");
00080             line_start = 1;
00081             break;
00082         case ' ':
00083             if (!line_start)
00084                 *out++ = *in;
00085             break;
00086         case '{':    /* skip all {\xxx} substrings except for {\an%d}
00087                         and all microdvd like styles such as {Y:xxx} */
00088             an += sscanf(in, "{\\an%*1u}%c", &c) == 1;
00089             if ((an != 1 && sscanf(in, "{\\%*[^}]}%n%c", &len, &c) > 0) ||
00090                 sscanf(in, "{%*1[CcFfoPSsYy]:%*[^}]}%n%c", &len, &c) > 0) {
00091                 in += len - 1;
00092             } else
00093                 *out++ = *in;
00094             break;
00095         case '<':
00096             tag_close = in[1] == '/';
00097             if (sscanf(in+tag_close+1, "%127[^>]>%n%c", buffer, &len,&c) >= 2) {
00098                 if ((param = strchr(buffer, ' ')))
00099                     *param++ = 0;
00100                 if ((!tag_close && sptr < FF_ARRAY_ELEMS(stack)) ||
00101                     ( tag_close && sptr > 0 && !strcmp(stack[sptr-1].tag, buffer))) {
00102                     int i, j, unknown = 0;
00103                     in += len + tag_close;
00104                     if (!tag_close)
00105                         memset(stack+sptr, 0, sizeof(*stack));
00106                     if (!strcmp(buffer, "font")) {
00107                         if (tag_close) {
00108                             for (i=PARAM_NUMBER-1; i>=0; i--)
00109                                 if (stack[sptr-1].param[i][0])
00110                                     for (j=sptr-2; j>=0; j--)
00111                                         if (stack[j].param[i][0]) {
00112                                             out += snprintf(out, out_end-out,
00113                                                             "%s", stack[j].param[i]);
00114                                             break;
00115                                         }
00116                         } else {
00117                             while (param) {
00118                                 if (!strncmp(param, "size=", 5)) {
00119                                     unsigned font_size;
00120                                     param += 5 + (param[5] == '"');
00121                                     if (sscanf(param, "%u", &font_size) == 1) {
00122                                         snprintf(stack[sptr].param[PARAM_SIZE],
00123                                              sizeof(stack[0].param[PARAM_SIZE]),
00124                                              "{\\fs%u}", font_size);
00125                                     }
00126                                 } else if (!strncmp(param, "color=", 6)) {
00127                                     param += 6 + (param[6] == '"');
00128                                     snprintf(stack[sptr].param[PARAM_COLOR],
00129                                          sizeof(stack[0].param[PARAM_COLOR]),
00130                                          "{\\c&H%X&}",
00131                                          html_color_parse(avctx, param));
00132                                 } else if (!strncmp(param, "face=", 5)) {
00133                                     param += 5 + (param[5] == '"');
00134                                     len = strcspn(param,
00135                                                   param[-1] == '"' ? "\"" :" ");
00136                                     av_strlcpy(tmp, param,
00137                                                FFMIN(sizeof(tmp), len+1));
00138                                     param += len;
00139                                     snprintf(stack[sptr].param[PARAM_FACE],
00140                                              sizeof(stack[0].param[PARAM_FACE]),
00141                                              "{\\fn%s}", tmp);
00142                                 }
00143                                 if ((param = strchr(param, ' ')))
00144                                     param++;
00145                             }
00146                             for (i=0; i<PARAM_NUMBER; i++)
00147                                 if (stack[sptr].param[i][0])
00148                                     out += snprintf(out, out_end-out,
00149                                                     "%s", stack[sptr].param[i]);
00150                         }
00151                     } else if (!buffer[1] && strspn(buffer, "bisu") == 1) {
00152                         out += snprintf(out, out_end-out,
00153                                         "{\\%c%d}", buffer[0], !tag_close);
00154                     } else {
00155                         unknown = 1;
00156                         snprintf(tmp, sizeof(tmp), "</%s>", buffer);
00157                     }
00158                     if (tag_close) {
00159                         sptr--;
00160                     } else if (unknown && !strstr(in, tmp)) {
00161                         in -= len + tag_close;
00162                         *out++ = *in;
00163                     } else
00164                         av_strlcpy(stack[sptr++].tag, buffer,
00165                                    sizeof(stack[0].tag));
00166                     break;
00167                 }
00168             }
00169         default:
00170             *out++ = *in;
00171             break;
00172         }
00173         if (*in != ' ' && *in != '\r' && *in != '\n')
00174             line_start = 0;
00175     }
00176 
00177     out = FFMIN(out, out_end-3);
00178     while (!strncmp(out-2, "\\N", 2))
00179         out -= 2;
00180     while (out[-1] == ' ')
00181         out--;
00182     out += snprintf(out, out_end-out, "\r\n");
00183     return in;
00184 }
00185 
00186 static const char *read_ts(const char *buf, int *ts_start, int *ts_end,
00187                            int *x1, int *y1, int *x2, int *y2)
00188 {
00189     int i, hs, ms, ss, he, me, se;
00190 
00191     for (i=0; i<2; i++) {
00192         /* try to read timestamps in either the first or second line */
00193         int c = sscanf(buf, "%d:%2d:%2d%*1[,.]%3d --> %d:%2d:%2d%*1[,.]%3d"
00194                        "%*[ ]X1:%u X2:%u Y1:%u Y2:%u",
00195                        &hs, &ms, &ss, ts_start, &he, &me, &se, ts_end,
00196                        x1, x2, y1, y2);
00197         buf += strcspn(buf, "\n") + 1;
00198         if (c >= 8) {
00199             *ts_start = 100*(ss + 60*(ms + 60*hs)) + *ts_start/10;
00200             *ts_end   = 100*(se + 60*(me + 60*he)) + *ts_end  /10;
00201             return buf;
00202         }
00203     }
00204     return NULL;
00205 }
00206 
00207 static int srt_decode_frame(AVCodecContext *avctx,
00208                             void *data, int *got_sub_ptr, AVPacket *avpkt)
00209 {
00210     AVSubtitle *sub = data;
00211     int ts_start, ts_end, x1 = -1, y1 = -1, x2 = -1, y2 = -1;
00212     char buffer[2048];
00213     const char *ptr = avpkt->data;
00214     const char *end = avpkt->data + avpkt->size;
00215 
00216     if (avpkt->size <= 0)
00217         return avpkt->size;
00218 
00219     ff_ass_init(sub);
00220 
00221     while (ptr < end && *ptr) {
00222         ptr = read_ts(ptr, &ts_start, &ts_end, &x1, &y1, &x2, &y2);
00223         if (!ptr)
00224             break;
00225         ptr = srt_to_ass(avctx, buffer, buffer+sizeof(buffer), ptr,
00226                          x1, y1, x2, y2);
00227         ff_ass_add_rect(sub, buffer, ts_start, ts_end, 0);
00228     }
00229 
00230     *got_sub_ptr = sub->num_rects > 0;
00231     return avpkt->size;
00232 }
00233 
00234 AVCodec ff_srt_decoder = {
00235     .name         = "srt",
00236     .long_name    = NULL_IF_CONFIG_SMALL("SubRip subtitle"),
00237     .type         = AVMEDIA_TYPE_SUBTITLE,
00238     .id           = CODEC_ID_SRT,
00239     .init         = ff_ass_subtitle_header_default,
00240     .decode       = srt_decode_frame,
00241 };