> >   how do i turn this filtering off? is it necessary for me to

> > dive into the FFDSHOW code to do this?


> For now try BMP export instead of PNG. This will give you images very close to

> the original. I'm now investigating why png export is different.


  did that, here is generated bitmap: http://galeb.etf.bg.ac.yu/~uzi/ffdshow/ffdshow%20grab.bmp


  you were right about closeness to what is beeing displayed, but not entirely. with BMP grab, resulting green in rectangles is RGB(0, 255, 0), which is what it should be (that is what mplayer returns, too). but that is not what i get from FFDSHOW (VMR9). i use small pixel shader and custom renderer (put VMR9 in renderless mode) to mask all green pixels (chroma key effect). that is how i know that green in rectangles is around RGB(x, 240, y), which is more like PNG grab result.

  on the other hand, edges of BMP grab are more like what i get from VMR9 (FFDSHOW). it seems that some sort of blending occured (when i compare BMP FFDSHOW grab with mplayer -vo png) which leads to green oreol around my chroma key figures...

  i don't want to be misunderstood, when i say blending i don't mean artefact that is due to chroma subsampling (even pixel boundary). i understand how subsampling works, and i know how to overide it (i plan to use even pixel boundary for masking). it is this additional postprocessing that is a mistery to me...


  best regards,

  aleksandar