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IDProjectCategoryView StatusDate SubmittedLast Update
0001969OpenMPTPlayback Compatibilitypublic2026-05-04 21:532026-05-04 22:04
ReporterWibi Assigned To 
PrioritynormalSeverityminorReproducibilityalways
Status newResolutionopen 
PlatformLinux (Wine)OSDebianOS VersionDebian 12
Product VersionOpenMPT 1.32.09.00 / libopenmpt 0.8.6 (current stable) 
Summary0001969: Modules are arbitrarily judged not to be Amiga modules if lowpass filter (E0x) is toggled 8 or more times in pattern data
Description

This is a strange limitation that is frustrating to come across as a composer. If I toggle the low-pass filter with E0x too often then the Amiga resampler will be disabled when loading the file and E0x will have no effect. I don't know if this is some overzealous heuristic, or if there is actually some issue on real Amiga consoles with E0x being toggled too much, but any permutation of E0x plays back as expected in pt2-clone on Linux, so there is at least a precedent for programs simulating Amiga trackers to allow toggling E0x arbitrarily often.

Steps To Reproduce
  1. Make a new Amiga module.
  2. Fill out the first 7 rows on column 1 with the following effects:
    E01
    E00
    E01
    E00
    E01
    E00
    E01
  3. Save, close, and reopen the module. Notice the resampler is "Default (Amiga Resampler)".
  4. Add an E00 on the 8th row.
  5. Save, close, and reopen the module. Notice the resampler is "Default (Sinc + LP)".
Additional Information

This heuristic(?) doesn't check the overall sequence but each independent pattern; if pattern 0 contains 2 E0x toggles and appears four times in the sequence then E0x will still be enabled, but if pattern 0-3 each contain 2 E0x toggles each then E0x will be disabled.

Attached are example modules demonstrating this quirk as well as the module I was working on when I discovered this behavior.

filtertest_7_e0x_toggles.mod.gz and filtertest_8_e0x_toggles_in_sequence.mod.gz should have the Amiga resampler enabled.

filtertest_8_e0x_toggles.mod.gz, filtertest_8_e0x_toggles_acrosspatterns.mod.gz, and Wibi-_dub_for_airports.mod.gz should have the Amiga resampler disabled.

TagsNo tags attached.
Attached Files
Wibi_-_dub_for_airports.mod.gz (135,055 bytes)
filtertest_7_e0x_toggles.mod.gz (7,346 bytes)
filtertest_8_e0x_toggles.mod.gz (7,344 bytes)
filtertest_8_e0x_toggles_in_sequence.mod.gz (7,358 bytes)
filtertest_8_e0x_toggles_across_patterns.mod.gz (7,397 bytes)
Has the bug occurred in previous versions?Yes
Tested code revision (in case you know it)OpenMPT-1.32.01.00

Activities

Wibi

Wibi

2026-05-04 22:04

reporter   ~0006668

Another way to replicate this: play back STK.formula1 by Romeo Knight, observe that the Amiga resampler is functional despite the presence of many E0x toggles, then save it as an Amiga module and reopen it. The Amiga resampler will be disabled. This makes me think it's a heuristic problem if it affects loading MOD files but not STK files.

STK.formula1.gz (75,155 bytes)

Issue History

Date Modified Username Field Change
2026-05-04 21:53 Wibi New Issue
2026-05-04 21:53 Wibi File Added: Wibi_-_dub_for_airports.mod.gz
2026-05-04 21:53 Wibi File Added: filtertest_7_e0x_toggles.mod.gz
2026-05-04 21:53 Wibi File Added: filtertest_8_e0x_toggles.mod.gz
2026-05-04 21:53 Wibi File Added: filtertest_8_e0x_toggles_in_sequence.mod.gz
2026-05-04 21:53 Wibi File Added: filtertest_8_e0x_toggles_across_patterns.mod.gz
2026-05-04 21:55 Wibi Platform Linux => Linux (Wine)
2026-05-04 22:04 Wibi Note Added: 0006668
2026-05-04 22:04 Wibi File Added: STK.formula1.gz
2026-05-04 22:04 Wibi Steps to Reproduce Updated