[Libav-user] Creating vob files and setting start timecode

francesco at bltitalia.com francesco at bltitalia.com
Mon Oct 27 10:33:30 CET 2014

Hi to all
I am using ffmpeg libraries in order to create .vob files and all works fine.
(I use the code in the example muxing.c)
Now I am attempting to set the start timecode in order to simplify
concatenation of two .vob files.  That is the idea is to have two .vob
files: one, for example,  from 0 to 3 sec and one fron 3 sec to 6 sec.  I
can create them but I can't set the start timecode to 3 sec in the second
file.  I attempt to modify the start_time in AVFormatContext and the
start_time in both video and audio stream, but no changes in output. I
attempt to set two different values: 10 and 600 but no changes. This is the
snippet for setting 600 as start time:

   _avFmtContext->start_time = 600;
   _avFmtContext->start_time_realtime = 600;

   ofmt = _avFmtContext->oformat;
   if (ofmt->video_codec != CODEC_ID_NONE)
   { ff_vd_st = add_stream(&vd_codec,ofmt->video_codec); }
    else {return false;}
   if (ofmt->audio_codec != CODEC_ID_NONE)
   {  ff_au_st = add_stream(&au_codec, ofmt->audio_codec);}
    else {return false;}

   ff_vd_st->start_time = 600;
   ff_au_st->start_time = 600;

First question : Is feasible to set starting time when creating .vob files ?
Start_time is an __int64; is expressed in seconds, frames or SCR units ?

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