mp3Trim 1.70 beta 12
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mp3Trim 1.70 main new feature is automatic volume normalization. 
If you have MP3s that are too low, that should help you figuring out 
how much amplification you can safely apply.

To get it working, load an MP3 and click on the 'auto' button in the 'volume 
control' box. That starts the analysis. When completed, mp3Trim shows how 
much amplification is possible (in dB, value below the 'auto' button) and 
updates the volume control bar.

Automatic volume normalization works by decompressing an MP3 in memory. 
From this process, mp3Trim determines what is the maximum amplitude and then
the maximum amplification possible that won't produce clipping in the output. 
Too much amplification forces MP3 decompressors (i.e. players) to clip the 
output and that introduces distortions.

Right now, the method of detection is crude (mp3Trim look for the maximum 
sample only, so it has a tendency to over-evaluate the maximum volume because 
a single max sample determines the volume for the whole track) and more 
sophisticated ways of determining the maximum amplitude will find their 
ways into the next version. In particular, a suggestion has been to allow the 
user to specify how much % of the song should be below the clipping limit. 
That would allow better control for tracks with big dynamic swings or that 
have been ripped from vinyl records with cracks and pops that easily exceed 
the average volume.

I'll add batch to mp3Trim PRO when I feel that the normalization can apply
to many MP3s in batch, probably mp3Trim PRO 1.80, so in a few months. Right
now, I think of it more as a quick way to get an indication of the level of 
an MP3, and then adjust the level manually.

Anyway, it looks pretty good, so give it a shot and let me know of any problem.
Decompressing the MP3 is a CPU intensive process, so it can take a little 
while, depending on your machine. The blue progress-bar gives visual feedback 
about the process.

Good luck!
Jean Nicolle -- Jan 4th 2001