libextractor

mpeg_extractor.c (5506B)

---

 /*
      This file is part of libextractor.
      Copyright (C) 2004, 2005, 2006, 2009, 2012 Vidyut Samanta and Christian Grothoff
 
      libextractor is free software; you can redistribute it and/or modify
      it under the terms of the GNU General Public License as published
      by the Free Software Foundation; either version 3, or (at your
      option) any later version.
 
      libextractor 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
      General Public License for more details.
 
      You should have received a copy of the GNU General Public License
      along with libextractor; see the file COPYING.  If not, write to the
      Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
      Boston, MA 02110-1301, USA.
  */
 
 /**
  * @file plugins/mpeg_extractor.c
  * @brief plugin to support MPEG files
  * @author Christian Grothoff
  */
 #include "platform.h"
 #include "extractor.h"
 #include <mpeg2dec/mpeg2.h>
 
 
 /**
  * Give meta data to extractor.
  *
  * @param t type of the meta data
  * @param s meta data value in utf8 format
  */
 #define ADD(s,t) do { if (0 != ec->proc (ec->cls, "mpeg", t, \
                                          EXTRACTOR_METAFORMAT_UTF8, \
                                          "text/plain", s, strlen (s) \
                                          + 1)) goto EXIT; \
 } while (0)
 
 
 /**
  * Main entry method for the 'video/mpeg' extraction plugin.
  *
  * @param ec extraction context provided to the plugin
  */
 void
 EXTRACTOR_mpeg_extract_method (struct EXTRACTOR_ExtractContext *ec)
 {
   mpeg2dec_t *handle;
   const mpeg2_info_t *info;
   void *buf;
   ssize_t avail;
   mpeg2_state_t state;
   char format[256];
   char lformat[256];
   char gop_format[256];
   int have_gop;
   uint64_t fsize;
   unsigned int fail_count;
   int did_seek;
   int fmt1;
   int fmt2;
   int mime;
   int fpal;
   int fntsc;
   int fsecam;
   int fmac;
 
   if (NULL == (handle = mpeg2_init ()))
     return;
   if (NULL == (info = mpeg2_info (handle)))
   {
     mpeg2_close (handle);
     return;
   }
   fsize = ec->get_size (ec->cls);
   buf = NULL;
   have_gop = 0;
   fail_count = 0;
   did_seek = 0;
   fmt1 = 0;
   fmt2 = 0;
   mime = 0;
   fpal = 0;
   fntsc = 0;
   fsecam = 0;
   fmac = 0;
   lformat[0] = '\0';
   while (1)
   {
     state = mpeg2_parse (handle);
     switch (state)
     {
     case STATE_BUFFER:
       if (fail_count > 16)
         goto EXIT; /* do not read large non-mpeg files */
       fail_count++;
       if (0 >= (avail = ec->read (ec->cls,
                                   &buf,
                                   16 * 1024)))
         goto EXIT;
       mpeg2_buffer (handle, buf, buf + avail);
       break;
     case STATE_SEQUENCE:
       fail_count = 0;
       if (0 == mime)
       {
         mime = 1;
         ADD ("video/mpeg",
              EXTRACTOR_METATYPE_MIMETYPE);
       }
       snprintf (format,
                 sizeof(format), "%ux%u",
                 info->sequence->width, info->sequence->height);
       if (0 != strcmp (lformat,
                        format))
       {
         strcpy (lformat,
                 format);
         ADD (format, EXTRACTOR_METATYPE_IMAGE_DIMENSIONS);
       }
       switch (info->sequence->flags & SEQ_VIDEO_FORMAT_UNSPECIFIED)
       {
       case SEQ_VIDEO_FORMAT_PAL:
         if (0 == fpal)
         {
           fpal = 1;
           ADD ("PAL", EXTRACTOR_METATYPE_BROADCAST_TELEVISION_SYSTEM);
         }
         break;
       case SEQ_VIDEO_FORMAT_NTSC:
         if (0 == fntsc)
         {
           fntsc = 1;
           ADD ("NTSC", EXTRACTOR_METATYPE_BROADCAST_TELEVISION_SYSTEM);
         }
         break;
       case SEQ_VIDEO_FORMAT_SECAM:
         if (0 == fsecam)
         {
           fsecam = 1;
           ADD ("SECAM", EXTRACTOR_METATYPE_BROADCAST_TELEVISION_SYSTEM);
         }
         break;
       case SEQ_VIDEO_FORMAT_MAC:
         if (0 == fmac)
         {
           fmac = 1;
           ADD ("MAC", EXTRACTOR_METATYPE_BROADCAST_TELEVISION_SYSTEM);
         }
         break;
       default:
         break;
       }
       if ((info->sequence->flags & SEQ_FLAG_MPEG2) > 0)
       {
         if (0 == fmt1)
         {
           fmt1 = 1;
           ADD ("MPEG2", EXTRACTOR_METATYPE_FORMAT_VERSION);
         }
       }
       else
       {
         if (0 == fmt2)
         {
           fmt2 = 1;
           ADD ("MPEG1", EXTRACTOR_METATYPE_FORMAT_VERSION);
         }
       }
       if ( (0 == did_seek) &&
            (fsize != -1) &&
            (fsize > 1024 * 256 * 2) )
       {
         /* skip to the end of the mpeg for speed */
         did_seek = 1;
         ec->seek (ec->cls,
                   fsize - 256 * 1024,
                   SEEK_SET);
       }
       break;
     case STATE_GOP:
       fail_count = 0;
       if ( (NULL != info->gop) &&
            (0 != info->gop->pictures) )
       {
         snprintf (gop_format,
                   sizeof (gop_format),
                   "%02u:%02u:%02u (%u frames)",
                   info->gop->hours,
                   info->gop->minutes,
                   info->gop->seconds,
                   info->gop->pictures);
         have_gop = 1;
       }
       break;
     case STATE_SLICE:
       fail_count = 0;
       break;
     case STATE_END:
       fail_count = 0;
       break;
     case STATE_INVALID:
       goto EXIT;
     default:
       break;
     }
   }
 EXIT:
   if (1 == have_gop)
     ADD (gop_format, EXTRACTOR_METATYPE_DURATION);
   mpeg2_close (handle);
 }
 
 
 /* end of mpeg_extractor.c */