Well yeah, from my experience MMD0 and MMD1 files play rather well, while MMD2+ files don't...

High octaves are not played correctly.
Synth sounds are not supported?
I've created testfiles for playing full scale of notes from C-1 to F-B, with sample and synth instrument (separate MED).
Please, find the corresponding audio recordings from real Amiga 500 (PAL) and spectrum plots for easier understanding of sample and synth instrument playback rates on each octave:
https://1drv.ms/f/s!Ahrc_3u_IRCdznbo9bvuJ0yinFHX
Also, read the Readme.txt for more detailed description.
Finally, feel free to ask me more about OctaMED playback on Amiga. I can play back and record audio references of suggested MED files.

Thanks for the test cases. I suppose the exact behaviour here might depend on the software mixing flag, as I guess the additional octave only work "as intended" when that flag is set?

21:28 < zoner> hello, not sure if the MED format is very well supported, but I stumbled across a doctor awesome song that is seriously messed up in libopenmpt: http://amp.dascene.net/downmod.php?index=19536

Re "Not really a new issue": MED/OctaMED support has been spotty since the early days of ModPlug Plugin/Player/Tracker. I clearly remember doing some mail correspondence with Olivier back in the 90s, and he did some minor changes based on my feedback to improve the MED playback somewhat, but in my experience MP has never been a good platform for playing back MED/OctaMED modules.

I'd be happy support any effort to improve this. I used an Amiga in the period 1991-97, and made a number of MEDs using MED 3.00, OctaMED 3/4/5 and SoundStudio 1 during this time, including multichannel stuff. I still have most of my stuff from this period, as well as some other MED stuff I know have issues in OpenMPT.

One key issue is timing. OctaMED has a number of different parameters that affects speed, including:

• Ticks/row, works (mostly) like in SoundTracker, defaults to 6 (side note: MED modules can also have an ST flag, which is supposed to give better compatibility with Soundtracker/Protracker. Basically it toggles wether or not some effects (volume slide, note slide etc) should kick in on the first tick of each individual line)
• A separate speed setting that defaults to 33, which is handled at least three different ways: For 4-chan modules a speed of 33 is approximately the same as 125 BPM, but for multichannel modules it is handled differently, and if you use the later introduced HQ mode (higher samplerate for software mixing) it is yet again handled differently
• A BPM mode, which can be used instead of the old speed setting. Same as Protracker.

Some other issues I have noted:

• Only four channels of multichan MMD2 modules are imported
• Only the first song in multi-modules is loaded
• Synth and hybrid instruments are not supported

At the moment there is sadly not much you could help with - I have started working on a new loader a long time ago but the MED format is so (unnecessarily) complex that it's not exactly fun to work on this feature. I'd say about half of the new loader is done, probably - which means there is still a lot of work to do. It might happen in OpenMPT 1.29 if we are very lucky, or OpenMPT 1.30 - but no promises.

Once the loader is done, expertise from OctaMED users will of course be useful for testing the new code.

I went back to the new MED loader and finished up a few things - it seems like we can get a much improved MED loader for 1.29, but it will most likely not contain support for synth instruments, but most other stuff should hopefully work a lot better than before. I think there will be some stuff for you to test in the next few days.

Currently I still have some issue with "IFFOCT" multi-samples - if any OctaMED user has some experience with those and can provide instruments other than 3- or 5-octave instruments, that would be fantastic.

@sherekhan If you could provide some multi-song modules, that would also be appreciated.

r12564 / OpenMPT 1.29.00.49, soon available from https://builds.openmpt.org/builds/ adds the new and improved loader. The following features have been added / improved:

• IffOct (multisampled) instruments and "ExtSample" sample type
• Delta samples
• More pattern commands
• More accurate portamento commands (only via libopenmpt, as OpenMPT will still have to play them like MOD/XM)
• Hold and Decay
• VSTi (yes, really) and MIDI output
• Multiple songs
• Probably a lot more stuff I forgot.

And yes, synthesized instruments are missing. They will probably come later. Still, please let me know how the new loader works for you.

From med2xm.zip -> Arkanoid99.oss -> pat 4 -> row 93.
The tone portamento undershoots, resulting in offtone.

Tested with openmpt-win32-1.30.00.02-r12932 in win7 VM.

I failed to read "More accurate portamento commands (only via libopenmpt, as OpenMPT will still have to play them like MOD/XM)" point of last post before writing.
My apologies.

Though manually rewriting porta values(303->304 and 302->303) did fix the bass.

For newly found issues, please open new issues. Let's not keep this one open forever.

(and this kind of "manual rewrite" you did will not always be that simple, especially if there are more ticks per row, which is why OpenMPT cannot do it automatically)