I'm using SDRTrunk and it creates wav files for the baseband and traffic where no aliases exist. I'm wanting to decode these into mp3 or even just listen to them. Is there software that can do this stand alone? Ie take a .wav file as an input?
You can play wave files directly in Windows. Just double click on the file name. Conversion software is widely available. An MP3 will be smaller than a wave file for storage. I mostly work in the Mac world so I don't have any Windows recommendations. I use Pro Audio Converter. They may have a Windows version. I think it was free.
There is probably a good way to use the baseband file to decode the audio, probably by opening it with SDR# or SDR++ and piping the VFO into DSD with vbcables or a virtual sink, but the simpler solution may be to make a new catch all alias to catch all the other groups you don't have on your main listening (similar to a blacklist or a whitelist), and log and record the decoded audio. Should be able to do so by toggling off the listen button and toggling on the record button. Haven't tried it for myself, so I can't tell you if it will work or not, but should be worth a shot.