Drac, below are the instructions included within encoder and decoder:
Encoder setup for trespasser use. Only mono, 22050 sample_rate .pcm waves can
be encoded into ima/dvi adpcms. If you have a stereo (44100 sample_rate) you
wish to encode, first convert it to single channel, 22050, then encode to ima/
dvi adpcm format.
The encoded waves are still not perfect, but they sound good enough to import
& use in_game. Much better than the original encoder released earlier - I al-
so took a temp_pcm wav (was a converted stereo to mono, 22050 for player use),
encoded and imported that and the music sounded quite good.

Reb.
Useage: Drag n' drop utility. Decodes ima/dvi adpcm (format 20) to standard
pcm wave.
Sample_rates: Code assumes mono as 22050 & stereo as 44100. Whether stereo
or mono, current code outputs mono, pcm wave. (The two sample_rates are the
only frequencies dealt with, so reading & writing out individual headers was
not needed -
The decoder class was searched out to decode the game trespasser's odd_ball
block alignment of 1028/2056. Although windows environment can play ima/dvi
waves natively, it does require standard block alignments of 512/1024. Thus,
looking to play the waves inside my audio program that was written to access
the game's packed audio files, I was lured into this decoding process -
Code is included, the ima class is courtesy of J.d. Medhurst (aka tixy). The
remainder of the mess is mine. Feel free to change the code in whatever way
you'd like, tailor it to meet your own needs. Hopefully, the next person to
require doing this sort of thing won't go insane looking for the solution -
Reb.
As for creating cau files, tpareader does that. The how to should be in the help
files. I'm pretty sure it's not complicated, but I can't remember the control layout.
It's just been too long for my feeble mind to recall -