Ok, I did some experiments, to see if I could infer empirically what these options mean.
(please notice: I'll call a "UT-bar" a bar in your UT template, and a "SONG-bar" a bar in your song to be played back using your UT).
I wanted to test the following hypotheses:
1. a "Riff" (as mentioned in the UT development settings) is a SONG-bar where a chord is present. So, a "non-riff" is a SONG-bar without a chord (in other words, a SONG-bar in which the chord indicated in previous bars is played back by BIAB)
2A. a "fill" (as mentioned in the UT development settings) is a SONG-bar that precedes a change of chords
2B. a "fill" is a SONG-bar that precedes a change of substyle (from A to B, or from B to A).
So, I did some testing to see if the following two settings worked according to the hypotheses above. The settings are:
- Don’t start a new Riff on this bar
- Only Play this for a fill
I found that:
- it seems that hypothesis 1 might be true or very close to the truth. In other words, if you set "Don't start a new Riff on this bar" on some UT-bars in your UT template, those UT-bars are only played back in a SONG-bars when there's no chord indicated.
If this is confirmed to be the actual function of this setting, this is very useful, for example for performances with a legato between UT-bars.
- I am more uncertain about the "fill". It seems that hypothesis 2B is closer to the truth. But, be warned, I found exceptions.
Anyway, if 2B is true or close to be true, that means that if you set "Only Play this for a fill" on some UT-bars, then BIAB will play back those UT-bars "mostly" on SONG-bars that precede a change of substyle. So, while I found that this is true, HOWEVER, I also found that BIAB plays back those UT-bars in other SONG-bars as well (that is, in SONG-bars that don't precede a change of substyle). And that threw me off, because the setting says "ONLY play ...". So this means that the actual rule must be somewhat different. Or maybe the setting doesn't work properly, I don't know.
Regardless, even with this ambiguity, this is still a useful setting, because you can (almost) be sure that SONG-bars that precede substyle changes will be played by specific UT-bars of your choice.
Anyway, this is what I discovered so far. Be warned, I could very well be totally wrong, I could have made mistakes etc etc etc. I am not sure of anything at all
Also, I have no idea about what happens when 2 or more chords are present in the SONG-bar (or in the UT-bar).
Hope this helps those of you working with UTs.
If PG Music wants to pitch in ...