There might be better ways to implement this change, I just thought a prompt would be best. Really, the main issue I wanted to highlight here is the fact that splitting a stereo sample to mono for an entire instrument for .it compression purposes is incredibly tedious.

Really, the main issue I wanted to highlight here is the fact that splitting a stereo sample to mono for an entire instrument for .it compression purposes is incredibly tedious.

Do you mean converting to a fully Impulse Tracker compatible module representation, or do you just care about the samples being compressed in general? Because as highlighted in this forum post, you can actually enable compression for stereo samples in IT modules as well. This is currently disabled by default because various older software will not load such samples as stereo samples, but it might be time to revise this default setting now that ten years have passed.

I was aware that a lot of older software and older versions of software did not support the compressed stereo samples. Many of the communities I'm in were under the same impression, mainly because that default setting implies it wasn't supported. This forum post seems to suggest otherwise, however I would like clarification on that fact: Did IT2.15 support compressed stereo samples? I feel that's the benchmark, as if you wanted to use compressed stereo samples in an impulsetracker module when it was never even supported, you should just use the mptm format, because that's basically an MPT hack at that point.

You might want to create a new issue for this to discuss there, I don't want to sidetrack this issue mainly because I feel it would still be a useful feature. XM doesn't support stereo but you can import stereo samples, so if you're working to the limitations of XM, this would still be incredibly beneficial.

My main gripe with the way it works as it stands is that if I wanted to split a stereo sample in an instrument with multiple samples, I would either manually remap the sample to be in the same instrument and adjust the note mapping or I would want all of the samples to be split into a new instrument automatically; there's really no use case as it stands where I would want to only split one sample in an instrument but not the others, and have a new instrument to deal with. And when you think about it, if you're splitting a sample in an instrument with only 1 sample mapped the entire way through, if it targeted all samples in the instrument, the only sample there is still "all samples in the instrument".

Did IT2.15 support compressed stereo samples?

Impulse Tracker never supported stereo samples in any capacity, neither compressed nor uncompressed.

I see some value in the suggestion, I just thought that this information might work as a good enough workaround for you for the time being.

Of course! I appreciate the consideration. As a side note, thank you for your continued support and development of OpenMPT, I really get the impression you're passionate about the project.

One question, though: wasn't there a paid version of ImpulseTracker that supported stereo samples? How were those handled?

No, the registered version of Impulse Tracker adds the stereo WAV writer, i.e. for exporting your songs in stereo. The playback engine stays the same. Impulse Tracker, just like Scream Tracker, defined a flag for stereo samples in the sample header but never made use of it.

For the record, the way this works currently makes it so that only the instrument that is currently selected by the sample is duplicated (by default, this is the first instrument in the list that uses that sample, unless you manually select another instrument in the list). It doesn't touch any other instruments that the sample is used by. I honestly question why it even duplicates the instrument at all; the way it currently works makes it more of annoyance than a feature.

EDIT: I'm mistaken. I split a sample in a module that I thought had been sample mapped to two instruments, but one of them was unmapped. Oops. Should've paid better attention.