Frame By Frame

[yety]

I am a developer using axvlc in C#, I've figured out solutions to a lot of problems so far, but now i have run in to something which i am almost certain lies with the underlying framework of libvlc.
I have attempted to implement a frame forwards and frame backwards button, the code originally looked something like
vlc.input.time += 1000/fps
and vlc.input.time-=1000/fps
but i noticed that whenever i set vlc.input.time to a value, it would immediately add extra time to that value. if vlc.input.time = 10 and i added 33, i would go look at the result and it would be 58 instead of 43.
i figured it was stepping forward by a little less than half a frame to render or something to that effect, so i subtracted an extra half of a frame time from the time, giving me something like
vlc.input.time = vlc.input.time +-1000/fps - 500/fps
it worked perfectly on that video, but when i moved to a different video type(first was .avi, second try was .mov) with the same frame rate it jumped back by more than an entire frame every time I was stumped. After searching around for about a week, I have decided to make an account here and ask if it is related to libvlc and the way it plays different video types.
If anyone has suggestions or recommendations, it would be very much appreciated

[Jean-Baptiste Kempf]

libvlc has a frame-forward function, but not a frame-backward one.