Hi,

As you've pointed out, stretching RTs to fit slower tempos or shrinking them to fit faster tempos introduces the likelihood of creating audio artifacts. This depends on the instrument. Like you, I've found that piano RTs don't respond well to change.

A few years ago, PG Music used to recommend that -10bpm slower and +15bpm faster was a good range for most RTs. I don't know if this is still recommended or not.

If you want to get good sounds, MIDI Supertracks will allow for greater variation in tempo but the output sound quality will depend on the synthesiser you use. I find that with EZ Keys, MIDI Supertracks sound exactly like the real thing.

Other than that, it's possible to restrict BIAB to using non-transposed tracks where possible. This will help reduce the artifacts but may not eliminate them. The setting is found in "Song Settings" and it's called "Avoid transposition in Realtracks" -- activate this option.

With the above option active, BIAB will look for RTs that are exact and not transpose a close key. For example, if you enter an Ebm chord, with the option inactive, BIAB may well substitute Dm and transpose it upwards a semitone. With the option active, though, BIAB will look for Ebm and only transpose if the Ebm chord does not exist in the RT's audio track.

The reason I mention this option is because stretching an already transposed chord will increase the likelihood of creating artifacts.

Regards,
Noel



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