With respect to Audacity plugins, I think you'll find most don't work well at all. Last I used Audacity, it didn't support VST plugin's UI, and instead substituted is own UI. So all the knobs / faders / buttons, etc. turned into a single type of slider, and all the values for the controls changed from the actual VST value and into a value between 0 and 1. Using Voxengo's free MS plugin, MSED, for example...
...resulted in the following UI changes:
- Inline / Decode / Encode button turned into a slider with values from 0 to 1. You'll have to map at what point between 0 and 1 the functionality changes from Inline to Decode to Encode.
- Mid Gain knob turned into a slider with values from 0 to 1. You'll have to map how the interim values between 0 and 1 correspond to dB settings.
- Side Gain knob turned into a slider with values from 0 to 1. You'll have to map how the interim values between 0 and 1 correspond to dB settings.
You have to do this type of mapping for every control on every VST plugin you want to use with Audacity. PITA, and one of the reasons I no longer use Audacity.
As for cross-fading, the way I used to do it (there might be a better way, dunno, but not that I recall) was simply to employ a fade to each track independently:
- Set up Track A in the Track # 1 slot.
- Set up Track B in the Track #2 slot.
- Align the two tracks so the amount of time during which they overlap matches the length of the crossfade you'd like to employ.
- Fade-out Track A, starting the fade-out at the time when Track B starts to play and ending when Track A ends.
- Fade-in Track B, starting at Track B's beginning and ending when Track A ends.
Visually, it looks something like this:
[--------------TRACK A-------fade-out]
[fade-in--------------TRACK B--------------]