libavcodec/srtdec.c
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 /*
  * SubRip subtitle decoder
  * Copyright (c) 2010  Aurelien Jacobs <aurel@gnuage.org>
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * FFmpeg is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 #include "libavutil/avstring.h"
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 #include "libavutil/common.h"
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 #include "libavutil/intreadwrite.h"
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 #include "libavutil/parseutils.h"
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 #include "avcodec.h"
 #include "ass.h"
 
 static int html_color_parse(AVCodecContext *avctx, const char *str)
 {
     uint8_t rgba[4];
     if (av_parse_color(rgba, str, strcspn(str, "\" >"), avctx) < 0)
         return -1;
     return rgba[0] | rgba[1] << 8 | rgba[2] << 16;
 }
 
 enum {
     PARAM_UNKNOWN = -1,
     PARAM_SIZE,
     PARAM_COLOR,
     PARAM_FACE,
     PARAM_NUMBER
 };
 
 typedef struct {
     char tag[128];
     char param[PARAM_NUMBER][128];
 } SrtStack;
 
 static const char *srt_to_ass(AVCodecContext *avctx, char *out, char *out_end,
                               const char *in, int x1, int y1, int x2, int y2)
 {
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     char *param, buffer[128], tmp[128];
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     int len, tag_close, sptr = 1, line_start = 1, an = 0, end = 0;
     SrtStack stack[16];
 
     stack[0].tag[0] = 0;
     strcpy(stack[0].param[PARAM_SIZE],  "{\\fs}");
     strcpy(stack[0].param[PARAM_COLOR], "{\\c}");
     strcpy(stack[0].param[PARAM_FACE],  "{\\fn}");
 
     if (x1 >= 0 && y1 >= 0) {
         if (x2 >= 0 && y2 >= 0 && (x2 != x1 || y2 != y1))
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             snprintf(out, out_end-out,
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                             "{\\an1}{\\move(%d,%d,%d,%d)}", x1, y1, x2, y2);
         else
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             snprintf(out, out_end-out, "{\\an1}{\\pos(%d,%d)}", x1, y1);
         out += strlen(out);
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     }
 
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     for (; out < out_end && !end && *in; in++) {
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         switch (*in) {
         case '\r':
             break;
         case '\n':
             if (line_start) {
                 end = 1;
                 break;
             }
             while (out[-1] == ' ')
                 out--;
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             snprintf(out, out_end-out, "\\N");
             if(out<out_end) out += strlen(out);
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             line_start = 1;
             break;
         case ' ':
             if (!line_start)
                 *out++ = *in;
             break;
         case '{':    /* skip all {\xxx} substrings except for {\an%d}
                         and all microdvd like styles such as {Y:xxx} */
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             len = 0;
             an += sscanf(in, "{\\an%*1u}%n", &len) >= 0 && len > 0;
             if ((an != 1 && (len = 0, sscanf(in, "{\\%*[^}]}%n", &len) >= 0 && len > 0)) ||
                 (len = 0, sscanf(in, "{%*1[CcFfoPSsYy]:%*[^}]}%n", &len) >= 0 && len > 0)) {
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                 in += len - 1;
             } else
                 *out++ = *in;
             break;
         case '<':
             tag_close = in[1] == '/';
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             len = 0;
             if (sscanf(in+tag_close+1, "%127[^>]>%n", buffer, &len) >= 1 && len > 0) {
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                 if ((param = strchr(buffer, ' ')))
                     *param++ = 0;
                 if ((!tag_close && sptr < FF_ARRAY_ELEMS(stack)) ||
                     ( tag_close && sptr > 0 && !strcmp(stack[sptr-1].tag, buffer))) {
                     int i, j, unknown = 0;
                     in += len + tag_close;
                     if (!tag_close)
                         memset(stack+sptr, 0, sizeof(*stack));
                     if (!strcmp(buffer, "font")) {
                         if (tag_close) {
                             for (i=PARAM_NUMBER-1; i>=0; i--)
                                 if (stack[sptr-1].param[i][0])
                                     for (j=sptr-2; j>=0; j--)
                                         if (stack[j].param[i][0]) {
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                                             snprintf(out, out_end-out,
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                                                             "%s", stack[j].param[i]);
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                                             if(out<out_end) out += strlen(out);
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                                             break;
                                         }
                         } else {
                             while (param) {
                                 if (!strncmp(param, "size=", 5)) {
                                     unsigned font_size;
                                     param += 5 + (param[5] == '"');
                                     if (sscanf(param, "%u", &font_size) == 1) {
                                         snprintf(stack[sptr].param[PARAM_SIZE],
                                              sizeof(stack[0].param[PARAM_SIZE]),
                                              "{\\fs%u}", font_size);
                                     }
                                 } else if (!strncmp(param, "color=", 6)) {
                                     param += 6 + (param[6] == '"');
                                     snprintf(stack[sptr].param[PARAM_COLOR],
                                          sizeof(stack[0].param[PARAM_COLOR]),
                                          "{\\c&H%X&}",
                                          html_color_parse(avctx, param));
                                 } else if (!strncmp(param, "face=", 5)) {
                                     param += 5 + (param[5] == '"');
                                     len = strcspn(param,
                                                   param[-1] == '"' ? "\"" :" ");
                                     av_strlcpy(tmp, param,
                                                FFMIN(sizeof(tmp), len+1));
                                     param += len;
                                     snprintf(stack[sptr].param[PARAM_FACE],
                                              sizeof(stack[0].param[PARAM_FACE]),
                                              "{\\fn%s}", tmp);
                                 }
                                 if ((param = strchr(param, ' ')))
                                     param++;
                             }
                             for (i=0; i<PARAM_NUMBER; i++)
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                                 if (stack[sptr].param[i][0]) {
                                     snprintf(out, out_end-out,
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                                                     "%s", stack[sptr].param[i]);
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                                     if(out<out_end) out += strlen(out);
                                 }
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                         }
                     } else if (!buffer[1] && strspn(buffer, "bisu") == 1) {
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                         snprintf(out, out_end-out,
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                                         "{\\%c%d}", buffer[0], !tag_close);
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                         if(out<out_end) out += strlen(out);
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                     } else {
                         unknown = 1;
                         snprintf(tmp, sizeof(tmp), "</%s>", buffer);
                     }
                     if (tag_close) {
                         sptr--;
                     } else if (unknown && !strstr(in, tmp)) {
                         in -= len + tag_close;
                         *out++ = *in;
                     } else
                         av_strlcpy(stack[sptr++].tag, buffer,
                                    sizeof(stack[0].tag));
                     break;
                 }
             }
         default:
             *out++ = *in;
             break;
         }
         if (*in != ' ' && *in != '\r' && *in != '\n')
             line_start = 0;
     }
 
     out = FFMIN(out, out_end-3);
     while (!strncmp(out-2, "\\N", 2))
         out -= 2;
     while (out[-1] == ' ')
         out--;
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     snprintf(out, out_end-out, "\r\n");
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     return in;
 }
 
 static const char *read_ts(const char *buf, int *ts_start, int *ts_end,
                            int *x1, int *y1, int *x2, int *y2)
 {
     int i, hs, ms, ss, he, me, se;
 
     for (i=0; i<2; i++) {
         /* try to read timestamps in either the first or second line */
         int c = sscanf(buf, "%d:%2d:%2d%*1[,.]%3d --> %d:%2d:%2d%*1[,.]%3d"
                        "%*[ ]X1:%u X2:%u Y1:%u Y2:%u",
                        &hs, &ms, &ss, ts_start, &he, &me, &se, ts_end,
                        x1, x2, y1, y2);
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         buf += strcspn(buf, "\n");
         buf += !!*buf;
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         if (c >= 8) {
             *ts_start = 100*(ss + 60*(ms + 60*hs)) + *ts_start/10;
             *ts_end   = 100*(se + 60*(me + 60*he)) + *ts_end  /10;
             return buf;
         }
     }
     return NULL;
 }
 
 static int srt_decode_frame(AVCodecContext *avctx,
                             void *data, int *got_sub_ptr, AVPacket *avpkt)
 {
     AVSubtitle *sub = data;
     int ts_start, ts_end, x1 = -1, y1 = -1, x2 = -1, y2 = -1;
     char buffer[2048];
     const char *ptr = avpkt->data;
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     const char *end = avpkt->data + avpkt->size;
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     int size;
     const uint8_t *p = av_packet_get_side_data(avpkt, AV_PKT_DATA_SUBTITLE_POSITION, &size);
 
     if (p && size == 16) {
         x1 = AV_RL32(p     );
         y1 = AV_RL32(p +  4);
         x2 = AV_RL32(p +  8);
         y2 = AV_RL32(p + 12);
     }
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     if (avpkt->size <= 0)
         return avpkt->size;
 
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     while (ptr < end && *ptr) {
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         if (avctx->codec->id == AV_CODEC_ID_SRT) {
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             ptr = read_ts(ptr, &ts_start, &ts_end, &x1, &y1, &x2, &y2);
             if (!ptr)
                 break;
         } else {
             // Do final divide-by-10 outside rescale to force rounding down.
             ts_start = av_rescale_q(avpkt->pts,
                                     avctx->time_base,
                                     (AVRational){1,100});
             ts_end   = av_rescale_q(avpkt->pts + avpkt->duration,
                                     avctx->time_base,
                                     (AVRational){1,100});
         }
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         ptr = srt_to_ass(avctx, buffer, buffer+sizeof(buffer), ptr,
                          x1, y1, x2, y2);
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         ff_ass_add_rect(sub, buffer, ts_start, ts_end-ts_start, 0);
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     }
 
     *got_sub_ptr = sub->num_rects > 0;
     return avpkt->size;
 }
 
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 #if CONFIG_SRT_DECODER
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 /* deprecated decoder */
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 AVCodec ff_srt_decoder = {
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     .name         = "srt",
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     .long_name    = NULL_IF_CONFIG_SMALL("SubRip subtitle with embedded timing"),
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     .type         = AVMEDIA_TYPE_SUBTITLE,
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     .id           = AV_CODEC_ID_SRT,
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     .init         = ff_ass_subtitle_header_default,
     .decode       = srt_decode_frame,
 };
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 #endif
 
 #if CONFIG_SUBRIP_DECODER
 AVCodec ff_subrip_decoder = {
     .name         = "subrip",
     .long_name    = NULL_IF_CONFIG_SMALL("SubRip subtitle"),
     .type         = AVMEDIA_TYPE_SUBTITLE,
     .id           = AV_CODEC_ID_SUBRIP,
     .init         = ff_ass_subtitle_header_default,
     .decode       = srt_decode_frame,
 };
 #endif