Can anyone please explain the various settings in the Quantsize Matrix tab and what they do? The options are Default, MPEG standard & CG/Animation

Also the special settings:

-Output YUV data as Basic YCbCr not CCIR601
-Use floating point DCT (While using SSE, always ON)
-No motion search for still picture by half pixel

And
-Soften block noise (for intra block and non-intra block)

Thanks in advance