I did get 64bit DGDecodeNV to work in vapoursynth, which does do GPU deinterlacing and re-sizing. I found that where I needed to do both of these things, eg 1080i -> 576p (lesser storage space for lesser valued videos) plus ffmpeg's unsharp, all using GPU, then piping vapoursynth/DGDecodeNV results into ffmpeg sped up the end-to-end transforming/encoding process immensley as compared to native ffmpeg alone.
I did then start to go looking for GPU based filters including sharpeners however was advised this http://forum.doom9.org/showthread.php?p ... ost1793683
after looking at KNLMeansCL as a GPU denoiser.I believe that my filter is the exception, not the rule.
Do not focus yourself on gpu based filters.