http://www.mjbshaw.com/2012/04/seeking-in-ffmpeg-know-your-timestamp.html
*/
- ContentTime const u = time - _pts_offset;
+ ContentTime u = time - _pts_offset;
+ if (u < ContentTime ()) {
+ u = ContentTime ();
+ }
av_seek_frame (_format_context, _video_stream, u.seconds() / av_q2d (_format_context->streams[_video_stream]->time_base), AVSEEK_FLAG_BACKWARD);
avcodec_flush_buffers (video_codec_context());