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IDProjectCategoryView StatusLast Update
0001325OpenMPTFeature Requestpublic2020-05-23 10:16
ReporterASIKWUSpulse Assigned To 
PrioritylowSeverityminorReproducibilityN/A
Status newResolutionopen 
Summary0001325: linear FM volume in MPTM
Description

Reminded by this chat in the 1.28 FM+PCM example song compo forum thread:
https://forum.openmpt.org/index.php?topic=5981.msg45343#msg45343

This was a discussion on how hard it is to equalize volume between the exponetial volume handling of the OPL2/3 chip and the linear volume handling of the sample-engine in the tracker. This was the only and a bit tricky way to mix things in ST3, so it's full intention and nothing wrong - but there was contemplation over adding a linear FM volume feature for MPTM

No issue on it has been seen afterwards, and 2 years[about 1½ year actually] has passed, so it's probably good to bring the issue into existence so it doesn't fall into oblivion :)

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Has the bug occurred in previous versions?
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Saga Musix

Saga Musix

2020-05-18 07:02

administrator   ~0004331

Key quote from the thread:

I have contemplated at least adding an optional linear mode in MPTM, but the problem is that the sample volume range is identical to the OPL volume range (well, almost - OPL only goes from 0 to 63 rather than 64), meaning that there would be some inevitable loss of precision.

The key limitation is on OPL's side. If you were sliding MPTM volume from, say, 64 to 60, all of these would still translate to the same OPL volume, so you would be wasting a lot of possible volume values and couldn't use them for the detail that is required in the lower volumes. Without extending the total volume range in MPTM first (e.g. 0...255 or so), this is simply not useful.

Issue History

Date Modified Username Field Change
2020-05-17 23:15 ASIKWUSpulse New Issue
2020-05-18 07:02 Saga Musix Note Added: 0004331
2020-05-23 10:16 ASIKWUSpulse Description Updated View Revisions