Give me a sec, I'll write something for you
If you had a folder full of MP3 files, this would convert them to V 6 variable mp3 (~128kb variable)
Download Lame 3.99.5 from here
http://www.free-codecs.com/lame_encoder_download.htm
You only need this file from the zip.
lame.exe
chuck it in D:\mp3\lame.exe
then open notepad, and paste this in..
for %%i in (*.mp3) do "D:\mp3\lame.exe" -V 6 "%%i" "D:\mp3\out\%%~ni.mp3"
Save it as encoder.bat (or something) and chuck it on your desktop.
Also, create the folder d:\mp3\out
Now drag any mp3 and drag it
onto the encoder.bat file icon and it will convert all .mp3 files in that folder, leave the originals in tact and create the new ones in d:\mp3\out
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The V means variable bit rate, so it's not constantly 128 or 192 etc, it will go lower on quiet sections of the track, saving space, and higher when it requires, to keep sound quality.
If you want higher quality, change the
-V 6 to something lower..
0 = super quality, highest file size
9 = worst quality, lowest file size
I use V1 for making my mp3's