Glitchy leading silence re-encode logic

[GoogleCodeExporter]

I found that if I imported a MIDI, using an MP3 that was at 22KHz, the 
original.mp3 file was saved as expected.  When adding leading silence with the 
option of encoding, original.mp3 is decoded as expected, but the sample rate is 
not upscaled to 44.1KHz, so the resulting OGG file is not the proper sample 
rate.  Sound cues sound like they play correctly after this, but the chart is 
graphically out of sync with the audio during playback.

Original issue reported on code.google.com by raynebc on 10 Jul 2011 at 4:20