The research is based on GAX Engine V3. Information about V2 can be found at the end of the document.
FYI: GaXM is a tool that can analyze GAX data. You may find more information there.
FYI: You can find my IDA FLIRT signature for GAX V3 here. https://github.com/loveemu/ida-sig
FYI: Gaxtapper: Diagnostic tool / Automated GSF ripper for GAX Sound Engine.