Well, it depends on a lot of things. For sound effects, OGGs are decoded to PCM and stuffed into a DS buffer, so memory usage is the same no matter what format you use, unless you change teh quality. CPU usage will also be the same ingame no matter what format you use. There may be *some* quality degradation, but OGGs are pretty good at preserving quality.
So, OGG sound effects:
- Slightly longer load time (In-mission or mission loading, depending on whether the player chose to preload sounds or not.)
- No change in memory usage
- No change in CPU
- Smaller filesize
- Quality varies (Depending on bitrate, which affects the filesize)
Music, on the other hand, is decoded on the fly.
OGG Music:
- Slightly better mission load time
- Less memory usage
- Slightly more CPU usage
- Smaller filesize
- Quality varies
OGG is also preferable to ADPCM (Which I know Inferno used) - better quality with a smaller filesize, IMO.
Upsampling can actually help sound quality somewhat, depending on the compression and the original quality. Usually you get less hiss, but any distortion will become much more obvious. (I used a resampling winamp plugin to upsample the m4 music from FS1, and it helped quite a bit). You can also run it through an EQ afterwards, to get the range of the sound back - making the highs/lows stronger, making the sound seem less murky IMHO.
It's not a huge deal, with effects you can probably get away with 22050 hz anyway.
