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Saturday, November 26, 2005

Real Life Adventures: Mega Man Fun - Part 2

Well, fortunately I was too stubborn (or perhaps bored) to quit. So, I continued the next day (only had like 2 hours to work on it on Monday). Scouring the archives for information, I found several general types of files: 'ASF ', 'AUS ', and a large file type that had no header tag. So, where's the music?

Perhaps rather aimlessly, I began searching through the binaries, looking for some piece of information that might lead me to the music. As luck would have it, that's exactly what I found. The strings "SELECT JUNGLE" and "FrontEnd/Music/Jungle.aus" in close proximity. The former I had seen before - it was in the secrets menu in the game, and played a remix of one of the music tracks. This offered pretty convincing evidence that the AUS files were the ones I was looking for.

Naturally, my next step was to extract a couple of them and look at the format. While it was nothing I recognized, and had no apparent waveforms (and searching for AUS format on various sites yielded no information), the file format was striking: rows and rows of 16-byte data blocks. The fact that the blocks were 16 bytes large was obvious, due to the near invariance displayed by the first two bytes of each block. This immediately made me think of ADPCM, as some variants of it used 16-byte blocks of data. However, the format didn't resemble any ADPCM variant I'd seen before; nor did any of the couple dozen audio formats I tried saving with Cool Edit Pro have the striking block structure.

I again went searching the web, looking for a decoder. This time I searched for any type of PS2 audio file player, hoping that perhaps it was a common compression format in a different package (the AUS file). I happened upon the Mozzle Flash (MFAudio) player, which claimed to play several different game audio formats. I was disappointed to see that the only formats it would attempt to play without the proper file header were generic ADPCM and PCM. But I supposed that I should at least give the ADPCM a shot at the data.

Much to my surprise, music came out! Not only that, but loud music; fortunately, I had turned my sound way down, on the chance that it would play garbage and damage my speakers. Despite the obnoxious volume, it was playing music from the game, and I recognized it. Unfortunately, it wasn't playing it perfectly; crackles and distortions were clearly audible. Now what?

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