Thanks for posting this, Robert. I am not a fade guru, so I will refrain from comment about fades other than wondering if the fade shapes should be a separate control so as to make the “Transition type” list more readable (note that visually impaired users cannot scan the list visually but have to have it read to them).
As a side note, I hope we will get a command into Audacity in the not too distant feature to align tracks end-to-end, and possibly an import appended feature too (and Steve has a separate append-import plug-in https://forum.audacityteam.org/t/append-import/20421/1) . Would any such built-in append features in Audacity cause you to redesign this?
Some issues I found…
I don’t think the plug-in should be called “Chain” anything, to avoid conflict with the Audacity “Chains” feature. “Trim and Append”?
If I am correct, this always does Trim, but does it always do Chain (which you call something else - arrange - in the help)? The help seems to suggest arrange is always done, but it seems to fail in this artificial example:
1 Create a tone of 30s, amplitude 0.1
2 select about 0s to 10s, generate tone amplitude 0.8 in the selection
3 Edit > Select All
3 Edit > Duplicate
4 Apply your effect, threshold of -20 dB, Trim & chain up, overlap +0.1
5 I see the amplitude 0.1 tone removed at the end of the tracks, but no append
If the 0.1 tone is e.g. at 10s to 30s in a 1 minute tone where the 0.1 tone is sandwiched between 0.8 tone, there is no trim at -20 dB threshold. I have not attempted to look at the code (I’m not a programmer) but how does the effect determine what is the start and the end of the track - is this proportional to the length?
“Trim and align left” does not align with time zero if it is the only track selected. Does “align left” mean “align with time zero”?
“Extras _Help” in the GUI should probably be called “Extras and Help”. Choosing “Force First Call” displays another Help screen with examples of fades. Should those examples not be called from its own separate menu item?
Generally I think you need to explain “first call” and “last call” in the help more than you do. What does “the first track of a previous call is encountered” mean? Is it to do with user changing the vertical order of tracks?
The Help screens should comply with conventions, notably maximum characters per line =50 and maximum lines per screen =25. This would mean cutting down text or more screens, or distributing help in an accompanying text form (or only in the Debug window, if that is even possible).
The transition preview is most interesting - preview is on the “Nyquist Wishlist” - see https://forum.audacityteam.org/t/wish-list-preview-button-for-process-plug-ins/15155/1 . Until then, can preview be provided more generally in this way in Nyquist plug-ins (e.g. “Preview 5 seconds”, “Preview 10 seconds”)?
That said, I think the current transition preview is way too short, I am not even sure it is playing what I would want to hear (e.g. one second of the track coming to an end and one second of the track following). The help doesn’t really explain any more what I am supposed to be hearing.
Finally “db” everywhere needs to be corrected to “dB”.
Gale