upscaling bad source - which resize function to use?

The source is 384x288, 25fps progressive, cell phone quality, plenty of encoding artifacts, compressed in a format that is not very compatible with a lot of players. I want to re-encode it to something compatible with most players today (iPhone, PSP, PS3, etc.) - MP4 with AVC/AAC. To eliminate any issue related to the image size, I want to scale it to 640x480. That size should be definitely playable by most players. The important feature here is compatibility with existing players, and a future-proof format. The question is, which resize function to use? I could use BilinearResize() on the hypothesis that this function will "smooth" the artifacts somewhat. On the other hand, this may introduce blur. Or I could use Spline36Resize() in order to preserve as much of the original information as possible. On the other hand, this may accentuate the artifacts. I will do some experiments myself, but meanwhile I was wondering if somebody has already figured out a rule to apply in such cases - scaling up almost 2x an artifact-ish source. Assume the x264 bitrate is high enough so that no (visible) additional artifacts are introduced during this conversion.

The usual advice is nnedi twice and some denoising. e.g. nnedi(field=0,dh=true).turnleft().nnedi(field=0,dh=true).turnright() then some denoise / calming. Cheers, David.

just scale down after using nnedi...