hootvopm

This script converts a Hoot memory dump into an .opm instrument pack, suitable for the VOPM VST plugin. It's an extremely rudimentary way of extracting FM instruments from games, but it works.

Usage

./hootvopm.py [-b] -t chip_type input_file

Input file can also be - to read from stdin.

Output is dumped straight to stdout; redirect it to a file if you want to save it.

Pass -b to instead read straight binary data instead of comma-separated values.

Currently-supported chip types

• OPM
• OPN
• OPNA (equivalent to OPN)
• Raw data in 32-byte groups (see below)

Raw data format

Offset	Value
0x00	DT/MUL*
0x04	TL*
0x08	KS/AR*
0x0C	AMS-EN/D1R*
0x10	DT2/D2R*
0x14	D1L/RR*
0x18	FL/CON
0x19	AMS/PMS

Rows marked with * are groups of 4 bytes, one per operator.

Capturing memory in hoot

• Left- and right-clicking the "driver work" area flips between available memory pages. Scrolling the wheel in this area scrolls through the current page; you can also use Ctrl-(Up/Down/PgUp/PgDn) for this purpose.
• When you see the area you need to capture, use Ctrl-C to copy it to the clipboard. This copies the entire page to the clipboard in a human-readable format, with 16 comma-separated hex bytes per line (plus a comma at the end for whatever reason, but this is ignored).
• Paste this into a file, trimming it down to get the register area of the FM sound chip. Save it as whatever.

Tips

• Most chips (read: all of the ones currently supported by this script) have a 256-byte register area, meaning you'll need to trim it down to 16 lines.
• From what I've seen, the chip's register area almost always resides on the first page, starting either at 0x0000 or 0x0100.

Known issues

• Since the script looks at a simple static memory dump, it has no way of capturing certain data, instead replacing it with placeholders. These include:
  • LFO data
  • Operator on/off state; all operators are considered to be in use (this could potentially be inferred, though)
  • Panning, though VOPM doesn't seem to use this