with no doubt 64kbps/44.1khz. Why? Because with 44.1kHz you get better resolution for high frequency signals while processing the .wav file. When doing the compression encoding, that resolution will matter to retain sound quality, no matter what compression rate you use thereafter.
But in the end, what matters is your objective for it. If you are intending to put an audio file on some web site, maybe it won't really matter if it's 44.1kHz or 32kHz. When streaming, no one gives for the diference. But if you intend to make an audio-cd demo or something of the kind I would definitely suggest 44.1kHz, for any compression encoding rate you use.
Either one would be better than the re-compression MySpace does, for what that is worth. Take a look a frequency analysis of your MP3 before and after you upload it to MySpace and you'll see a notable absence where that high frequency content (>11 kHz) used to be.
Last edited by Per Lichtman; 09-04-2008 at 03:56 PM.
Reason: Missing Words
Basically you are trading highs for artifacts. I'd say that 64kbps/44.1khz would be worse as you are taking more information and shoving it down a narrower channel. That means more compression (22:1 vs 8:1) and more artifacts. As far as the high-frequency cutoff is concerned, we're talking about CD quality (20->20khz @ 44.1khz) vs FM quality (50->15khz @ 32khz). FM may not be CD but I think it's proven itself as acceptable.
All this said, your question doesn't make a lot of sense. The filesize will basically be determined by the length of the song and the bit rate. A 128kbps/44.1khz file will be roughly the same size and stream at the same rate as a 128kbps/32khz file - so what's the point? If you can use 128kbps/32khz you can use the accepted standard of 128kbps/44.1khz so you might as well go with it.
By the way, I confirmed the above by making three copies of a source wave file and encoding them with Lame into the three formats. File size ratios were as expected. To my 59 year-old ears the 32khz & 44.1 khz @ 128kbps files sounded almost the same. The 64kpbs/44.1khz file had a lot more artifacts.
Thanks, this was a nice way of winding down after a gig.