ffdshow avisynth Buffer back/ahead

[mark0077]

Hi,

Does anyone know in what circumstances the buffer back / ahead is needed in ffdshow. I'm asking as I'm using mpc-hc with LAV filters, with ffdshow solely to use SVP frame interpolation via avisynth scripts.

The SVP guys say the buffer ahead is crucial to SVP working correctly but I'm finding that even with it completely disabled in ffdshow, I'm getting absolutely perfect frame interpolation. This ffdshow page here seems to indicate the buffer ahead / back is only a workaround in ffdshow for filters that don't support being asked for a particular frame.

http://ffdshow-tryout.sourceforge.net/wiki/video:avisynth#buffer_back_ahead (http://ffdshow-tryout.sourceforge.net/wiki/video:avisynth#buffer_back_ahead)

Has anyone any experience with that, and maybe LAV Filers supports this? I'm getting some audio sync differences between the buffer being enabled / disabled, or enabled with different values so I want to basically nail down if the buffers are needed at all in your guys experience with different filters and maybe I can go from there on the audio sync problems its causing.

[vood007]

When you turn off Buffers a copy of the current frame is served if the requested frame is not available. Filters dont break this way but they also do NOT work for anything temporal. Use FFDShow OSD and select "Avisynth Info" to show requested and served frames. Audio desync may come from heavy multithreaded scripts that eat too much CPUs...

[mark0077]

hmm, with SVP enabled, ffdshow osd is saying that none are requested at all :S Audio desync in my case I think is being caused by incorrect timestamps I think rather than cpu / gpu as those are very low atm. I'll bring this back to the SVP guys.