Yeah your card should definitely be supported... I'll just blame it on opencl in avisynth being buggy. It's not too important anyway.
As for smoothd2, the documentation
is pretty good.
As I said, the qtype parameter's pretty useful.
Qtype (1, 2, 3, 4): Quant Type. Selects the type of quant-dequant processing that is used in the filtering. They are ordered by their deblocking strength from least strong to strongest. h263 intra and h263 inter, Qtype’s 2 and 4, ignore the matrix argument and use their own built in matrix.
1. mpeg intra
2. h263 intra
3. mpeg inter
4. h263 inter
The intra in Qtypes 1 and 2 referes to the encoding done for I-Frames. The inter in Qtypes 3 and 4 refers to the encoding done for P-frames and B-Frames. See http://www.fh-friedberg.de/fachbereiche ... ginnzi.htm
for a good introduction to mpeg coding. Different matrices are usually used when encoding I-Frames then when encoding P-Frames and B-Frames. All the information about how a particular frame was originally encoded, I-Frame, P-Frame, B-Frame, and Matrix value, has been lost by the time SmoothD2 is passed a frame to process, SmoothD2 does not do automatic intra-inter Qtype or matrix switching.
Generally you are supposed to manually set the qtype for the frame, but if you don't feel like spending all that effort, in the case of mpeg-2 DVDs, set it to 3 (which is mpeg inter).
That way it'll be much more effective in removing the blocking and mosquito noise at lower quant values, which is its filtering strength parameter. The default of 3 might not be enough for some of the most action intense scenes, but I really would suggest you to at least filter only those scenes at that point, since filtering clean scenes will just ruin them.
As for the other parameters, feel free to read the documentation, but I personally haven't found to be nearly as necessary and useful as these two, though I guess in some cases the matrix parameter could make wonders.