Is there any advantage to adding capability in a SNES program to change the loop point for a BRR sample in-game and real-time listen to the adjustments? Or can this optimization/Search for the best sounding loop point be done during Encoding?
It is possible to change the loop point during playback, but I doubt there is any advantages in doing this. The only advantage that came to my mind is if you're willing to play a white noise sample, then you could change the loop point to avoid hearing a pattern repeating too often.
I don't mean change the loop point during playback. I mean, I was wondering if it would be useful to be able to set a loop point, listen to the playback, change the loop point listen to the playback, in order to determine the best loop point to set forever. I haven't tried it but I thought it would help in searching for where to place the loop point. Once again, I am a little ahead of myself as I have no experience with loop points on BRR samples. Not yet at least.
Oh yeah, sorry I misinterpreted your original post.
You should use some other tracking program in order to "find the loop point". It's a somewhat complex topic. You can use Viena SF2 editor and use sound fonts (that's what I do).
I think the good way to convert a sample is to find the loop point BEFORE converting to BRR, and during the conversion resample the sample so that the looped section is a multiple of 16 samples (BRRtools can do this automatically for you if you specify a loop point).
Converting to BRR first and then setting a loop point is very likely to never work well.
When it comes to finding loop points there is basically two types : Short and long loops. Sometimes there is "hybrid" loops but they are rare.
Short loops simply consist in one period of the samples. They are useful for instruments with a simple tone without any effect like chorus. The loop point is extremely easy to find, as it consist of one period of the sound. The sample therefore have two stages, the "attack" phase where the sample is plaid, and the "looping" phase where the last period of the sample will play indefinitely. If you mess up the loop point it will sound fine, but the attack and looping phase won't be at the same pitch, which can be quite noticeable.
Long loops is for everything else, and consist of many period of the samples. They are used with samples with a chorus effects (like strings) or with single instrument samples of better quality than short loop samples (but they take more space too, in SPC's case this can be a problem). Finding a loop point can be harder for those samples. You'd have to find a point somewhere within the sample where the spectrum of a single oscillation is the same as the one of the last oscillation. If you get it wrong, you get a very noticeable click at every looping. Fortunately, those "clicks" are much less noticeable when merged in a complex musical piece.
I hope this will help you. Not that all I said is based on my personal experience with soundfonts and game music. The word I invented to describe things might not be adequate.