SD to HD with Avisynth
H.264 sample (~11MB) -- SimpleSlugUpscale v1.00, default settings; encoded with x264 revision 1745 (32bit, 8-bit depth from http://www.x264.nl/) using --preset slower --tune fastdecode --keyint 300 --sar 1:1
NTSC DV original (~60MB)
Sometimes your SD needs to be HD. Modern hardware and software can do respectable work on the fly, scaling things on playback, but on occasion you'll want, for example, to fit an old SD clip into an HD project, and you just have to do the best you can scaling it yourself, beforehand.
"Garbage in, garbage out." Yes, I know. Everyone loves to say that, and it's true, but also true is "'pretty good' in, 'Hey, that's a lot better than I thought it could be' out." Doesn't roll off the tongue quite as well, but that's beside the point. Some research along those lines revealed a set of tools that allowed me to upscale standard definition video clips to high definition dimensions at a quality level that astonished me.
Using the Avisynth scripting engine, and a variety of addons, I'll walk you through the process of achieving a result like the sample above. I imagine many of you are unfamiliar with Avisynth, and have only heard the name whispered in hushed tones, by hooded figures inhabiting the darkest corners of the internet, but you needn't worry. Experience would make this easier, yes, but a determined reader should be able to keep up; I'll only be assuming the most basic knowledge on your part.
You'll need a Windows PC, lots of time to process the script we'll be running, and the patience to sit through my obnoxiously lengthy explanations. If you meet those criteria, we can get started.