Audio groups

Audio groups are basically detached IFF files with just audio data. Audio group 0 is in the data.win directly, higher ones are stored in audiogroupn.dat. The file contains a FORM chunk with just AUDO in it.

The SOND entries have two values: GroupID and AudioID. GroupID specifies the ID of the group where the audio file resides, and AudioID is the index of the audio file in that group's AUDO chunk. So the structure goes like this:

snd_sound1: GroupID=0 AudioID=0
snd_sound2: GroupID=0 AudioID=1
snd_sound3: GroupID=1 AudioID=0
snd_sound4: GroupID=1 AudioID=1
snd_sound5: GroupID=0 AudioID=2
snd_sound6: GroupID=1 AudioID=2
snd_sound7: GroupID=1 AudioID=3

If the game doesn't use audio groups, then AGRP is totally empty (you don't even get a default group for the stuff inside data.win!)