compression test filter

[Forensic]

I need a plug-in that I can call in AVISYNTH that returns the estimated resulting compressed file size of the video file passed to it. This would replace the need to encode MPEG4 within in VirtualDub (2.5) just to denote the displayed estimated resulting file size.

The reason is that I will create a script to automatically test dozens of denoising/degraining filter combinations to determine which produces the clearest result, and thus smallest file size. I do not mind, and actually prefer, if this filter ran through the entire encoding process (without writing anything to the hard drive) so it could return the most accurate final file size. Any suggestions?