Time for the optimisation, but first, a little background on this.
This should be the absolutely last thing you will do with the VGM files. Do not attempt to optimise files before they're fully trimmed and tagged correctly. You won't be able to revert the process and the current tools were not meant for the updated format. If you attempt to edit files after the optimisation, there's a chance of corrupting them. You've been warned.
A few months ago we decided to start Project2612 because we love Mega Drive/Genesis soundtracks, and because there wasn't a good place to find quality soundtracks anywhere. (And let's face it, GYMs suck!) There were plenty of GYM files out there, but they were big, innacurate, didn't support loop or tags and just sounded terrible. There was no quality control or standard either. The only decent format for storing YM2612 data was VGM, but its good accuracy and no optimisation made files extremely large.
Regardless of that, Project2612 was started, and soon had a big collection of soundtracks, some over 20 MB in size. (Pulseman, formerly the biggest set, was 29.6 MB!) Size had always been an issue and was holding the VGM popularity down, but it was all we had. But then some nice folks, namely blargg, came around with an idea to solve this, proposing a few changes on the format that would optimise file sizes tremendously.
A couple of weeks of actual work resulted on the updated VGM format, 1.50, which now supports PCM sample banks. This new optimised version of the format was able to reduce file sizes tremendously, sometimes with over 75% of size reduction. This certainly removed the only barrier against VGM ruling as THE Mega Drive/Genesis music format, and all this is thanks to the following optimisation process you're going to use. :)
The program is small, very basic and runs on command line, but it does the job and does it well! To make your job easier, we included a handy batch (.BAT) file along with the program that will do all the hard job for you. Here's what you gotta do:
OptVGM will run through all files optimising each, and saving them inside the "optimised" folder that will show up. Once it's done, hit any key to close the command prompt, and then test the new files. Remember you will need an updated version of the VGM input plugin, v0.33 or better. Things should be OK, but in case of any errors, please report to us immediately.
With the VGM files optimised, you can delete the copies of optvgm.exe and optimise.bat, and all you have to do now is pack them up.