I found trial version of TMT 2. The program itself does not work well with W7 but its decoder works fine. There's no corruption or any visible pixelation. However, Arcsoft's decoder suffers the same problem as Microsoft's decoder; wrong ratio in anamorphic videos, which I later found out that actually caused by MPC-HC internal MKV splitter. I installed Haali Media Splitter and problems solved. Now I can use either Microsoft's or Arcsoft's decoder without ratio problem . Beside both of these decoders can decode MPEG-2 using DXVA as well (though I don't need it).
Thanks you everyone for your inputs.