I was wondering if there is any tool that will allow me to compare vbr mp3s.

Why?
I have encoded an album (Sheryl Crow Globe Sessions) with LAME v3.90.2-IC (from here), v3.91, and v3.92 (both from Mitiok's page).

All the v3.91 and v3.90.2-IC mp3s have different bitrates and sizes when compared to their v3.92 twins.

For instance:
-F --alt-preset extreme, RazorLame 1.1.5

Track 10, v3.90.2-IC - 223kbps (winamp & EncSpot), 7.90MB
Track 10, v3.91 - 223kbps (winamp & EncSpot), 7.90MB
Track 10, v3.92 - 219kbps (winamp & EncSpot), 7.74MB

Track 04, v3.90.2-IC - 228kbps (winamp & EncSpot), 7.86MB
Track 04, v3.91 - 228kbps (winamp & EncSpot), 7.86MB
Track 04, v3.92 - 222kbps (winamp & EncSpot), 7.66MB

What I would like to do is find some tool that shows me vbr throughout the timeline of the songs, so I can see where the differences are and take a listen to those areas.

In addition can anyone suggest why they are different? What changes to 3.92 would create these differences? As I assume the Mitiok files used the same compiler(3.92 and 3.91)

Thanks for any assitance.

Jon

Encspot 2 pro would show this, but it's not free.
This issue has been under lots of discussion.. Differences emerge because of different compilers/compiler settings.

thanks.

Can it be assumed that because the number of higher bit rate frames are lessened in 3.92, it is inferior at encoding? Or more efficient?

I took a look at the info for Track 4:

v3.92 -

128kbps 3%
160kbps 15%
192kbps 27%
224kbps 24%
256kbps 16%
320kbps 15%

avg bitrate 222
max reservoir 511
av reservoir 79
scalefac 16.2%


v3.91

128kbps 2%
160kbps 11%
192kbps 26%
224kbps 26%
256kbps 18%
320kbps 17%

avg bitrate 227
max reservoir 511
av reservoit 80
scalefac 17.3%

Lower the av reservoir the better correct? I don't quite understand this, something about overflow....

Could you maybe explain reservoir, and scalefac(tor)? Or point me in the right direction to find some info.


thanks! just trying to get a better handle on this stuff.

Robert Hegemann (one of the LAME developers) told me that he changed some compile options for ICC (Intel C Compiler) in LAME 3.92. The quality of the MP3s is not affected by this.

Don't understand how the mp3 is "not affected" by a lower average bitrate.
Either making it better or worse...it has to affect it.

Ok, let me rephrase it... the quality should not be affected to a degree where it is audible.

Next time i talk to Robert, i'll ask him some more about this.

thanks.