I have now figured out how the game resources of Donald Duck’s Playground (DDP) are mapped to the disk and created a tool to extract them. The resource formats are identical to what they are in AGI v2 DOS-based games, except that the SOUND format is different. Also, there might be slight differences in the LOGIC scripts since this game is using the AGI version 2.001. I also started to document the booter games in ScummVM wiki.
The SOUND resource format is actually very straightforward although it is less structured than it is for the later interpreter versions. It consists of varying sized sequences or “rows” of bytes that each end with a zero. These bytes are simply the values that are to be sent to the sound chip in the IBM PCjr (SN76489; three square wave generators and one noise generator). Each row contains the data for all the generators and is fixed length in time. Since all the bytes are supposed to be sent to the same I/O port in the IBM PCjr, there are no restrictions to how they should be ordered (with the exception that some updates need two bytes and the chip expects them to come in order). In fact, a row often contains only one zero, which means no data is sent to the sound chip, effectively skipping the row.
I suspect this is the format for AGI v1 SOUND resources as well. I will update the wiki about the SOUND resource format once I have verified this.
What comes to the reimplementation, I have added the detection for this game to ScummVM’s AGI engine. I have also implemented the player for SOUND resources. The game works but there are problems in some parts because ScummVM does not yet support some AGI v2.001 specific things. Will come back to this at some later time.