libavcodec/srtdec.c

   1 /*
   2  * SubRip subtitle decoder
   3  * Copyright (c) 2010  Aurelien Jacobs <aurel@gnuage.org>
   4  *
   5  * This file is part of FFmpeg.
   6  *
   7  * FFmpeg 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  * FFmpeg 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 FFmpeg; 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/common.h"
  24 #include "libavutil/intreadwrite.h"
  25 #include "libavutil/parseutils.h"
  26 #include "avcodec.h"
  27 #include "ass.h"
  28
  29 static int html_color_parse(AVCodecContext *avctx, const char *str)
  30 {
  31     uint8_t rgba[4];
  32     if (av_parse_color(rgba, str, strcspn(str, "\" >"), avctx) < 0)
  33         return -1;
  34     return rgba[0] | rgba[1] << 8 | rgba[2] << 16;
  35 }
  36
  37 enum {
  38     PARAM_UNKNOWN = -1,
  39     PARAM_SIZE,
  40     PARAM_COLOR,
  41     PARAM_FACE,
  42     PARAM_NUMBER
  43 };
  44
  45 typedef struct SrtStack {
  46     char tag[128];
  47     char param[PARAM_NUMBER][128];
  48 } SrtStack;
  49
  50 static void rstrip_spaces_buf(AVBPrint *buf)
  51 {
  52     while (buf->len > 0 && buf->str[buf->len - 1] == ' ')
  53         buf->str[--buf->len] = 0;
  54 }
  55
  56 static void srt_to_ass(AVCodecContext *avctx, AVBPrint *dst,
  57                        const char *in, int x1, int y1, int x2, int y2)
  58 {
  59     char *param, buffer[128], tmp[128];
  60     int len, tag_close, sptr = 1, line_start = 1, an = 0, end = 0;
  61     SrtStack stack[16];
  62
  63     stack[0].tag[0] = 0;
  64     strcpy(stack[0].param[PARAM_SIZE],  "{\\fs}");
  65     strcpy(stack[0].param[PARAM_COLOR], "{\\c}");
  66     strcpy(stack[0].param[PARAM_FACE],  "{\\fn}");
  67
  68     if (x1 >= 0 && y1 >= 0) {
  69         if (x2 >= 0 && y2 >= 0 && (x2 != x1 || y2 != y1))
  70             av_bprintf(dst, "{\\an1}{\\move(%d,%d,%d,%d)}", x1, y1, x2, y2);
  71         else
  72             av_bprintf(dst, "{\\an1}{\\pos(%d,%d)}", x1, y1);
  73     }
  74
  75     for (; !end && *in; in++) {
  76         switch (*in) {
  77         case '\r':
  78             break;
  79         case '\n':
  80             if (line_start) {
  81                 end = 1;
  82                 break;
  83             }
  84             rstrip_spaces_buf(dst);
  85             av_bprintf(dst, "\\N");
  86             line_start = 1;
  87             break;
  88         case ' ':
  89             if (!line_start)
  90                 av_bprint_chars(dst, *in, 1);
  91             break;
  92         case '{':    /* skip all {\xxx} substrings except for {\an%d}
  93                         and all microdvd like styles such as {Y:xxx} */
  94             len = 0;
  95             an += sscanf(in, "{\\an%*1u}%n", &len) >= 0 && len > 0;
  96             if ((an != 1 && (len = 0, sscanf(in, "{\\%*[^}]}%n", &len) >= 0 && len > 0)) ||
  97                 (len = 0, sscanf(in, "{%*1[CcFfoPSsYy]:%*[^}]}%n", &len) >= 0 && len > 0)) {
  98                 in += len - 1;
  99             } else
 100                 av_bprint_chars(dst, *in, 1);
 101             break;
 102         case '<':
 103             tag_close = in[1] == '/';
 104             len = 0;
 105             if (sscanf(in+tag_close+1, "%127[^>]>%n", buffer, &len) >= 1 && len > 0) {
 106                 if ((param = strchr(buffer, ' ')))
 107                     *param++ = 0;
 108                 if ((!tag_close && sptr < FF_ARRAY_ELEMS(stack)) ||
 109                     ( tag_close && sptr > 0 && !strcmp(stack[sptr-1].tag, buffer))) {
 110                     int i, j, unknown = 0;
 111                     in += len + tag_close;
 112                     if (!tag_close)
 113                         memset(stack+sptr, 0, sizeof(*stack));
 114                     if (!strcmp(buffer, "font")) {
 115                         if (tag_close) {
 116                             for (i=PARAM_NUMBER-1; i>=0; i--)
 117                                 if (stack[sptr-1].param[i][0])
 118                                     for (j=sptr-2; j>=0; j--)
 119                                         if (stack[j].param[i][0]) {
 120                                             av_bprintf(dst, "%s", stack[j].param[i]);
 121                                             break;
 122                                         }
 123                         } else {
 124                             while (param) {
 125                                 if (!strncmp(param, "size=", 5)) {
 126                                     unsigned font_size;
 127                                     param += 5 + (param[5] == '"');
 128                                     if (sscanf(param, "%u", &font_size) == 1) {
 129                                         snprintf(stack[sptr].param[PARAM_SIZE],
 130                                              sizeof(stack[0].param[PARAM_SIZE]),
 131                                              "{\\fs%u}", font_size);
 132                                     }
 133                                 } else if (!strncmp(param, "color=", 6)) {
 134                                     param += 6 + (param[6] == '"');
 135                                     snprintf(stack[sptr].param[PARAM_COLOR],
 136                                          sizeof(stack[0].param[PARAM_COLOR]),
 137                                          "{\\c&H%X&}",
 138                                          html_color_parse(avctx, param));
 139                                 } else if (!strncmp(param, "face=", 5)) {
 140                                     param += 5 + (param[5] == '"');
 141                                     len = strcspn(param,
 142                                                   param[-1] == '"' ? "\"" :" ");
 143                                     av_strlcpy(tmp, param,
 144                                                FFMIN(sizeof(tmp), len+1));
 145                                     param += len;
 146                                     snprintf(stack[sptr].param[PARAM_FACE],
 147                                              sizeof(stack[0].param[PARAM_FACE]),
 148                                              "{\\fn%s}", tmp);
 149                                 }
 150                                 if ((param = strchr(param, ' ')))
 151                                     param++;
 152                             }
 153                             for (i=0; i<PARAM_NUMBER; i++)
 154                                 if (stack[sptr].param[i][0])
 155                                     av_bprintf(dst, "%s", stack[sptr].param[i]);
 156                         }
 157                     } else if (!buffer[1] && strspn(buffer, "bisu") == 1) {
 158                         av_bprintf(dst, "{\\%c%d}", buffer[0], !tag_close);
 159                     } else {
 160                         unknown = 1;
 161                         snprintf(tmp, sizeof(tmp), "</%s>", buffer);
 162                     }
 163                     if (tag_close) {
 164                         sptr--;
 165                     } else if (unknown && !strstr(in, tmp)) {
 166                         in -= len + tag_close;
 167                         av_bprint_chars(dst, *in, 1);
 168                     } else
 169                         av_strlcpy(stack[sptr++].tag, buffer,
 170                                    sizeof(stack[0].tag));
 171                     break;
 172                 }
 173             }
 174         default:
 175             av_bprint_chars(dst, *in, 1);
 176             break;
 177         }
 178         if (*in != ' ' && *in != '\r' && *in != '\n')
 179             line_start = 0;
 180     }
 181
 182     while (dst->len >= 2 && !strncmp(&dst->str[dst->len - 2], "\\N", 2))
 183         dst->len -= 2;
 184     dst->str[dst->len] = 0;
 185     rstrip_spaces_buf(dst);
 186 }
 187
 188 static int srt_decode_frame(AVCodecContext *avctx,
 189                             void *data, int *got_sub_ptr, AVPacket *avpkt)
 190 {
 191     AVSubtitle *sub = data;
 192     AVBPrint buffer;
 193     int ts_start, ts_end, x1 = -1, y1 = -1, x2 = -1, y2 = -1;
 194     int size, ret;
 195     const uint8_t *p = av_packet_get_side_data(avpkt, AV_PKT_DATA_SUBTITLE_POSITION, &size);
 196
 197     if (p && size == 16) {
 198         x1 = AV_RL32(p     );
 199         y1 = AV_RL32(p +  4);
 200         x2 = AV_RL32(p +  8);
 201         y2 = AV_RL32(p + 12);
 202     }
 203
 204     if (avpkt->size <= 0)
 205         return avpkt->size;
 206
 207     av_bprint_init(&buffer, 0, AV_BPRINT_SIZE_UNLIMITED);
 208
 209         // TODO: reindent
 210             // Do final divide-by-10 outside rescale to force rounding down.
 211             ts_start = av_rescale_q(avpkt->pts,
 212                                     avctx->time_base,
 213                                     (AVRational){1,100});
 214             ts_end   = av_rescale_q(avpkt->pts + avpkt->duration,
 215                                     avctx->time_base,
 216                                     (AVRational){1,100});
 217
 218     srt_to_ass(avctx, &buffer, avpkt->data, x1, y1, x2, y2);
 219     ret = ff_ass_add_rect_bprint(sub, &buffer, ts_start, ts_end-ts_start);
 220     av_bprint_finalize(&buffer, NULL);
 221     if (ret < 0)
 222         return ret;
 223
 224     *got_sub_ptr = sub->num_rects > 0;
 225     return avpkt->size;
 226 }
 227
 228 #if CONFIG_SRT_DECODER
 229 /* deprecated decoder */
 230 AVCodec ff_srt_decoder = {
 231     .name         = "srt",
 232     .long_name    = NULL_IF_CONFIG_SMALL("SubRip subtitle"),
 233     .type         = AVMEDIA_TYPE_SUBTITLE,
 234     .id           = AV_CODEC_ID_SUBRIP,
 235     .init         = ff_ass_subtitle_header_default,
 236     .decode       = srt_decode_frame,
 237 };
 238 #endif
 239
 240 #if CONFIG_SUBRIP_DECODER
 241 AVCodec ff_subrip_decoder = {
 242     .name         = "subrip",
 243     .long_name    = NULL_IF_CONFIG_SMALL("SubRip subtitle"),
 244     .type         = AVMEDIA_TYPE_SUBTITLE,
 245     .id           = AV_CODEC_ID_SUBRIP,
 246     .init         = ff_ass_subtitle_header_default,
 247     .decode       = srt_decode_frame,
 248 };
 249 #endif