avisynth DirectShowSource capturing a/v sync issue

[logicom]

Hi,

I am using this script to capture from very basic graph and further down this is used as an input for streaming with ffmpeg.

V=DirectShowSource("OspreyInputV.GRF", audio=false, fps=25, pixel_type="YUY2", framecount=9999999)
A=DirectShowSource("OspreyInputA.GRF", video=False, fps=25, framecount=9999999)
AudioDub(V, A)
loop()

after 6 hours there is a noticeable drift - problem with a/v sync

Should this be addressed with something like

ensurevbrmp3sync()

or should a/v be re-clocked in the graph itself ?

Any ideas ?