Implement import of E-Tracker format

[mborik]

📝 Feature description

• E-Tracker is well known music tracker on Sam Coupé and there are still active composers.

💡 Expectations

• To support a migration of composers to our SAA1099Tracker we should implement import of their modules.

⚒️ Solution

• E-Tracker module import was already implemented in early iteration of this project (then called MIF85Tracker) here.
• We should just rewrite it into TypeScript and enable the menu item.
• Refactor all imports into src/tracker/file.import.ts

🔦 Additional context

[stefandrissen]

As a feature creep, perhaps also support importing compiled e-tracker tunes? Zxart.ee has hundreds, they can be manually decompiled with a tool I wrote back in the day (see https://www.worldofsam.org/products/fred-best-fred )

[mborik]

@stefandrissen Thank you for your suggestion. 🙏
It's great but I'll need some cooperation to make it happen.

support importing compiled e-tracker tunes

Is there any description of E-Tracker compilation format? It's backward compatible to module format?

they can be manually decompiled with a tool I wrote back in the day

Are there any sources of your decompiler in readable form that could act as blueprint?
As a bonus, would you be able to suggest an algorithm or JS/TS/anything code draft for this import? 😉

[stefandrissen]

No, unfortunately there's no description that I know of.

I do have a documented (disassembled) player.

I have also just found the source code to my d-compiler and added it to that repo.

[mborik]

Thank you for your repo and info, it will help a lot. 👍

[mborik]

@stefandrissen
Well, importing of E-Tracker compilation was a bit tough... ufff! 🥴
... but positions, patterns and ornaments are imported well and it seems OK. 🤞
I have a problem with samples.
I don't get a point how to handle sample format; It's pretty confusing for me that searching in 5th pointer from header and how it affecting a volume or repeating...? 🤔

SAA1099Tracker/src/tracker/file.import.ts

Line 521 in 55b31a5

// TODO FIXME: I don't know what's going on here!

[stefandrissen]

:-) from a quick scan of the D-Compiler at line 426 - I /think/ I understand your confusion.

The volume / noise mask are all stored as RLE deltas (deviation).