[theora] Number of frames

[Morten Winkler Jørgensen]

Hi All 

I am coding an application capable of playing theora movies using libtheora and libogg.
Now, I need to know the duration of a theora movie in frames.

I seem to be unable to find that information in the using either libtheora or libogg.
Google gave a hit proposing to read the file backwards till the magic "OggS" could be 
found and then scan forward to the framenumber field could be found.
Another way would be to decode all frames to the end of the move, and then count the frames as I
decode.

Neither approaches seem like the right one.

Can anybody tell me if I have missed something obvious or propose a third and better approach?

Regards, 
   Morten