Compare quality?

[QQ]

Greetings gang.

What programs should I use, to compare quality of decoded tracks, *technically*? I mean, yes, I know, even if the wave is more different from original than another, it might sound better, but this time, I want to compare how similar it is to original. By means of frequencies, and stuff.

I dont really have much knowledge about all that, but I should know basic principles of digital audio. So best would be to find some program which would display the differences in graphical way (eg frequency analysis?), and not just a bunch of numbers :)

So, any suggestions?

Oh, they should be downloadable;)

Thanks!

[DSPguru]

blind listening tests methods :
http://www.ff123.net/setup.html

i doubt there's a real point of comparing sound quality of decoded tracks by judging their visual form. (yea, that also includes frequency analysis)

Originally Posted by JohnV
No, graphs are never a better way to compare codecs. They may lead to totally wrong conclusions. Psychoacoustic perceptual audio is based on masking effect (temporal and frequency masking). You can't conclude from the graphs conclusively what you actually hear and what would be masked anyway. A codec with advanced psychoacoustic model may sound very much better but look much worse than a bad quality codec which looks good in spectral/frequency transform analysis. Also the temporal resolution of graphs are usually way too low in order to see temporal glitches or evaluate the audible effect.

[QQ]

even if there is no point in that, still, how could i measure "similarity" between two audio files?