Reading in the Developer Guide I find the following: "Please note that Intel Media SDK pipelines will only work with 4:2:0 subsampling.". Does this mean that it is not possible to deinterlace and maintain alpha with RGB32 input frames?
Intel Media SDK effectively ignores Alpha data in RGB bitmaps. Alpha would potentially be meaningful if the Media SDK VPP component was able to handle alternate output formats. But the fact is that VPP only supports output of NV12 (no alpha). Media SDK Encoder and Decoder components only accepts NV12 input.