Avisynth Virtual File SystemIf the tutorial up to now has worked out for you, and you're tired of installing software, I don't blame you for stopping right here. This next setup is a little more complicated, and if it's not something you need you might as well not bother. It's worth a peek, though, so stick around if you can.
There's an excellent explanation in the manual, but to summarize, the Avisynth Virtual File System turns an Avisynth script into a fake AVI file that almost any application can access. Avisynth, under normal circumstances, is triggered by software that both uses the Video for Windows media architecture and loads files through the standard Windows file handling interface. Open a .avs file with one of these programs and it won't know the difference between the script and an AVI; Avisynth works silently in the background, serving frames as they're needed.
Many useful programs don't operate this way, however. They use the DirectShow or QuickTime frameworks, or they use their own file handlers. Sometimes both. How do you get scripts into them without first spending the time and wasting the storage space to render gigantic intermediate files? Turns out there are several answers to that question, but the solution I've found most reliable is the AVFS.
To get it installed you'll need both the Pismo File Mount Audit Package (first thing on the page, click "Download Windows Install package") and AVFS itself. The File Mount Audit Package is straightforward, just run the installer and follow the prompts.
AVFS needs to be installed by hand, and as of AVFS 188.8.131.52, the instructions I'd provided in past versions of this tutorial no longer apply. Luckily the .zip file includes a readme with straightforward explanations of how to install and use AVFS. For the sake of future proofing, I won't repeat them here. It will suffice to say that once the software is installed and the script mounted, you can open the resultant fake AVI in a wide variety of applications that otherwise don't support Avisynth scripts as input.
That about does it! We've covered everything I can think to cover; you've got your video going into the script, passing through the deinterlacer, getting cropped and resized, and with this last bit you've got it in whatever application you like to use for video work. The only thing left is a note or two on problem solving.