Reading frame numbers in a local video file with precision

[Kenneth Feingold]

Hi Will,
Thanks very much for working with me on this, to whatever limit extent is
possible :-)
My application has a very simple pipeline. It uses playbin to show a video
file in a gtkgl window:

  data.playbin = gst_element_factory_make ("playbin", "playbin");
  videosink = gst_element_factory_make ("glsinkbin", "glsinkbin");
  gtkglsink = gst_element_factory_make ("gtkglsink", "gtkglsink");

 When I seek to a frame like this:

gst_element_seek_simple (data->playbin, GST_FORMAT_DEFAULT,
GST_SEEK_FLAG_FLUSH |GST_SEEK_FLAG_KEY_UNIT, 12345);
            send_seek_event (data);

/*and then in my seek function:*/
gst_element_send_event (data->video_sink, seek_event);

It actually takes me to precise frame #12345.

But, when I try to retrieve frame numbers while playing the file:
/* Query the current position in frames */
  if (gst_element_query_position (data->playbin, GST_FORMAT_DEFAULT,
&current)) {
    framenum=(current/1599.49);
    g_print ("Current Frame: %ld\n", framenum);
  }

I need to use that specific (kludge) factor  "framenum=(current/1599.49);"
in order to get *close* to the app giving me the right frame number. What
is curious is that with a different video file having a different length I
need to use a different divisor to get the "right" value. Is this related
to media duration/stream time?

I am working with mp4 and mov files, and I am wondering if compression
between frames is a factor? Would uncompressed video yield greater accuracy?

And, as I was wondering in my earlier post here, what values do you think
this:
gst_element_query_position (data->playbin, GST_FORMAT_DEFAULT, &current))

is giving me (without my kludge)?

Thanks again!
Ken
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