severe discrepancies in mp3 frame counts

Hello,

I'm seeing drastic discrepancies (an order of magnitude) between the mp3
frame counts reported by xmms and the perl module MP3::Info.  This happens 
with many, but not all, MP3 files I've tried.  Here are some example files:

"This Family Name" or "Distance" here:
http://www.purevolume.com/RidingBikes/music

"Slow Descent" in the music section here:
http://straylightrun.com/

XMMS reports:
Distance: 6394 frames
This Family Name: 9078 frames
Slow Descent: 13535 frames

But MP3::Info reports:
Distance: 68174 frames
This Family Name: 96802 frames
Slow Descent: 144313 frames

I'm using xmms version 1.2.10 and MP3::Info version 1.02.  Here's the code
I'm using:

#!/usr/bin/perl
use MP3::Info;
my $mp3 = new MP3::Info $ARGV[0];
print	  "$ARGV[0] : framecount is "
	. $mp3->frames
	. ", fps is "
	. sprintf("%.1f",($mp3->frames/$mp3->secs))
	. "\n";

...and in xmms, I'm just right-clicking on the track in the playlist and
choosing "View File Info."  My goal is to get an accurate FPS for any given
mp3, so that my script can resume playback of a paused track, by passing
--skip <FPS*elapsedtime> to mpg321.

Can anyone shed any light on this?

Thanks,
Anthony
http://nodivisions.com/