MAMEWorld Forums - Programming - Re: Problems with ripping digitized samples from arcade games

> I'd be interested to know too, as I figured the same thing when trying to edit a
> sound file from Rave Racer to erase annoying announcers. I would import the bin file
> in Audacity and select 6000Hz as that seemed to be the right right pitch, but there
> was a ton of static in the sound file and unsurprisingly, when I saved it, it was
> static in MAME, so I figured something else was set to the wrong format but couldn't
> figure it out and went though each option.
>
> You can ignore this part. In the end what worked for me was I just replaced the file
> with a blank one, which took out more a few more sounds than I wanted but somehow
> worked with no static.

Namco games sometimes have µlaw samples instead of plain PCM and may also need the bytes to be flipped in order to get anything useful out of them, otherwise it will sound distorted/garbled when loaded. Some games may even use a mix of µlaw and uncompressed PCM depending on the sound, I've noticed this with the Tekken games (S11/S12). If you open the Tekken 3 audio in Audacity you will notice that the µlaw sounds are very distorted when you load the ROM in that format. If you flip the bytes of the entire ROM (e.g. in a hex editor) the sounds will play properly. That said, some things still sound like garbage because of the low frequency (if anything the Namco sound hardware probably has something like a low pass filter to make it marginally better).

On a side note, Audacity is not the best way to edit sound ROMs, it slightly modifies/corrupts the data when either loading or saving the file (not sure which, unless it affects both) - you'll see what I mean when you load them side by side in a hex editor. If it isn't Audacity itself doing it, it's the encoder being used ("other compressed files" -> Unsigned 8-bit PCM). I'm using version 2.0.6 on this PC, no idea if it's been fixed in later versions or if the same thing still happens. You should always load and save as unsigned data when editing ROMs otherwise values like 00/FF or 7F/80 can switch around; this is not what Audacity is doing - the data is all over the place when saving regardless of what you do.

My old (and now dead) PC used to have an ancient version of Cool Edit Pro (I know, closed source commercial crap) but this program did not corrupt data unless you deliberately saved in a lossy format or used signed data.