0001469: GDM extra fine portamento effects are not correctly converted. - OpenMPT Issue Tracker

ID	Project	Category	View Status	Date Submitted	Last Update

0001469	OpenMPT	Playback Compatibility	public	2021-06-04 12:31	2021-06-04 19:13

Reporter	Lachesis	Assigned To	Saga Musix
Priority	normal	Severity	minor	Reproducibility	always
Status	resolved	Resolution	fixed
Platform	x64	OS	Windows	OS Version	10
Product Version	OpenMPT 1.29.10.00 / libopenmpt 0.5.9 (upgrade first)
Target Version	OpenMPT 1.29.11.00 / libopenmpt 0.5.10 (upgrade first)	Fixed in Version	OpenMPT 1.29.11.00 / libopenmpt 0.5.10 (upgrade first)

Summary	0001469: GDM extra fine portamento effects are not correctly converted.
Description	The following effects are not correctly converted by the GDM loader: `E8x` — Extra fine portamento up. This is left as the mod effect `E8x` (pan position). `E9x` — Extra fine portamento down. This is converted to `Q0x` (multi-retrigger). These might seem unusual, but this really is how 2GDM maps these effects. See the MenTaLguY document for reference (a format doc that is actually correct, for a change... it probably helps that BWSB was GPL by that point). OpenMPT converts the entire `Exx` block as if they're standard MOD effects. Following this further confirms that `E8x` is left as-is and `E9x` is converted to `CMD_RETRIG`, which lines up with what I see when I load a test module.
Steps To Reproduce	Do any of the following: Load the attached modules `gdm_fx.s3m` and `GDM_FX.GDM` into OpenMPT and compare the effects. (In this case, the `E8x` is converted to a volume channel effect.) Convert `gdm_fx.s3m` with 2GDM and compare. Load the attached module `LB2_7.GDM` in OpenMPT and look at patterns 17-22, channels 4 and 5. (In this case, `E8x` is left as-is.)
Additional Information	libxmp and MikMod convert these correctly but probably not in any releases (yet), as both had much worse handling of the fine effects before I patched them. An interesting note, even though these should be converted to `Exx` and `Fxx`, I found that BWSB doesn't actually implement continue variants of any of the fine portamento effects (unlike fine volume slide, which shares memory with regular volume slide). 2GDM evaluates `E00`/`F00` for these at conversion time for some reason.
Tags	No tags attached.

Has the bug occurred in previous versions?	Yes (1.29.5 tested).
Tested code revision (in case you know it)

Lachesis 2021-06-04 12:37 reporter ~0004785	Wish it had told me I couldn't upload GDMs before I submitted... � GDM_FX.GDM.zip (403 bytes) gdm_fx.s3m.zip (354 bytes) LB2_7.GDM.zip (119,817 bytes)

Saga Musix 2021-06-04 19:13 administrator ~0004787	Good find - I probably didn't read gdm.txt carefully enough when I wrote the GDM loader back then. Fixed in r15282.

Date Modified	Username	Field	Change
2021-06-04 12:31	Lachesis	New Issue
2021-06-04 12:37	Lachesis	Note Added: 0004785
2021-06-04 12:37	Lachesis	File Added: GDM_FX.GDM.zip
2021-06-04 12:37	Lachesis	File Added: gdm_fx.s3m.zip
2021-06-04 12:37	Lachesis	File Added: LB2_7.GDM.zip
2021-06-04 12:40	Saga Musix	Assigned To	=> Saga Musix
2021-06-04 12:40	Saga Musix	Status	new => assigned
2021-06-04 19:13	Saga Musix	Status	assigned => resolved
2021-06-04 19:13	Saga Musix	Resolution	open => fixed
2021-06-04 19:13	Saga Musix	Fixed in Version	=> OpenMPT 1.29.11.00 / libopenmpt 0.5.10 (upgrade first)
2021-06-04 19:13	Saga Musix	Target Version	=> OpenMPT 1.29.11.00 / libopenmpt 0.5.10 (upgrade first)
2021-06-04 19:13	Saga Musix	Note Added: 0004787