The current state of the art in audio signal interpolation Three questions:


What are all the metrics one can use to measure audio interpolation quality, objectively? (but also in terms of psychoacoustics if possible)
By those metrics, what is the current state of the art in audio interpolation?
Suppose I were to render two files from a sequence of notes from virtual instruments in two resolutions and then compare an upsampling of one file with the high-frequency rendered version, what software could one use to compare these objectively? - ideally using the before-mentioned metrics


So far, from I've been able to gather, these resamplers provide some of the best quality


http://www.mega-nerd.com/SRC/
http://sox.sourceforge.net/SoX/
http://www.izotope.com/tech/src/


One of the problems that these resamplers seem to have is pre- and post ringing.

I should note that of key interest is signal reconstruction (insofar as that term makes sense), so upsampling more than downsampling.

Edit: Interpolation time efficiency is irrelevant in this context.

Best regards,
The curious :-)
There is this pretty thorough comparison of resampling algorithms: http://src.infinitewave.ca/

You can see the tests they used there. Aliasing is a big one, and is easy to visualize with a spectrogram of a sine sweep. There's also high frequency response -- SRC can roll off high frequencies in addition to allowing them to cause aliasing. You can visualize phase response with the impulse response graph, or with a plot of the phase response.