0001260: Odd panbrello behavior when extracting MO3 files

ID	Project	Category	View Status	Date Submitted	Last Update

0001260	OpenMPT	Playback Compatibility	public	2019-09-10 22:37	2019-09-11 17:27

Reporter	Slender	Assigned To
Priority	normal	Severity	minor	Reproducibility	always
Status	closed	Resolution	no change required
Platform	x64	OS	Windows	OS Version	10
Product Version	OpenMPT 1.28.06.00 / libopenmpt 0.4.6 (upgrade first)

Summary	0001260: Odd panbrello behavior when extracting MO3 files
Description	Hi, I noticed that when extracting a MO3 file with UNMO3 and playing the extracted version, panbrello seems to pan at a much wider range than it normally would in the original MO3. Example file: https://www.dropbox.com/s/g65tj8cvhhinz4r/zuma.mo3?dl=1. When extracting this MO3, you'll notice that panbrello seems to pan over a much wider range than it does in the original MO3.
Tags	No tags attached.

Has the bug occurred in previous versions?
Tested code revision (in case you know it)

Saga Musix 2019-09-11 06:34 administrator ~0004059	Are you sure that's the right file? There is not a single panbrello effect in those patterns. Besides, there is no such thing as an "original" MO3. The original would be an IT file, and older MO3 files provide almost no information on which tracker was used to save the IT file, so all XMPlay or OpenMPT can do is guess which playback quirks to enable and which not.

Slender 2019-09-11 08:51 reporter ~0004060	Yes, there is a panbrello effect on the bongos, instruments 192 to 199.

Saga Musix 2019-09-11 17:26 administrator ~0004061	Panbrello is a pattern command (Yxx). You are referring to pan swing. Anyway, what's happening here is that the original IT file was saved with an earlier version of ModPlug Tracker, and in those versions the pan swing range was four times deeper than it should be. When decoding the MO3 file, OpenMPT correctly deduces that the file was made with such an older MPT version and automatically fixes the pan swing range to a fourth of the values stored in the file; when loading the UNMO3-ed version this is not possible, because we can no longer deduce that the file was made with an early version of MPT. This information is lost in UNMO3's decoding process.

Date Modified	Username	Field	Change
2019-09-10 22:37	Slender	New Issue
2019-09-11 06:34	Saga Musix	Note Added: 0004059
2019-09-11 08:51	Slender	Note Added: 0004060
2019-09-11 17:26	Saga Musix	Note Added: 0004061
2019-09-11 17:27	Saga Musix	Status	new => closed
2019-09-11 17:27	Saga Musix	Resolution	open => no change required