HMIDRV_HDAudio

This is a driver for Intel High Definition Audio controllers, for use with Human Machine Interface's (HMI's) Sound Operating System version 3, perhaps better known as HMIDRV.386. The project was inspired by Japheth's HDAUtils, and the idea is to give old DOS programs / games (such as Rayman) the ability to play sound through modern hardware. So far, it has been tested with the aforementioned Rayman, on MS-DOS 6.2 running on a PC from 2014 with this motherboard (to clarify, I'm booting DOS natively on the system, not with QEMU or the like).

The driver can interface with HDATSR.EXE from the Windows 3.1 HDA sound driver by Watlers World, available here. If this TSR is not present, the driver can attempt to allocate its own buffers using XMS (or directly from the DOS extender if paging is off). That said, the TSR is the most sure-fire way to ensure the driver has memory available for all the necessary buffers.

The driver can also hook MSCDEX to mix CD Audio into the stream, since modern optical drives tend not to have built-in analogue music players with direct connections to the sound card anymore.

At this point, the performance of the detector and driver seems satisfactory on Rayman Designer, which can detect arbitrary sound cards on startup using HMIDET.386. When both HMIDRV.386 and HMIDET.386 are patched, a fresh install of Rayman Designer can detect HD Audio hardware, and after closing and reopening, play sound and CD Audio through it. Further patching is required for Rayman Junior, which needs changes to SOUND.BIN (using the SOUNDBIN.ASM utility in the RAYTOOLS folder), and has an installer that only runs from CD, necessitating the use of the HMIREDIR tool (see RAYTOOLS/EXAMPLE.BAT for how I did it). Other games will likely have quirks of their own!

Limitations

• Looping sounds unfortunately skip when played through this driver, even though non-looping sounds are fine.
  • I suspect this is a feature of all "pseudo-DMA" SOS3 drivers - at some point, I'll check out the Gravis UltraSound driver under Dosbox and see if it has the same problem.
• Only tested with RATIONAL-type (i.e. DOS/4GW-like) DOS extenders, not FLASHTECK [sic] (i.e. FlashTek X-32VM and similar).
  • CD Audio won't work under FlashTek unless there is a DPMI host running behind it.
• Currently only supports 16-bit stereo playback
• CD Audio requires your drive to support raw reading
• Cannot run under Windows 3.1/9x with the aforementioned HDA sound driver running - they will conflict
• Detector doesn't seem to be useful in combination with certain game installers which contain a fixed list of known sound cards (so they will basically ignore this new unknown one even if it's detected)
  • Most versions of Rayman have an external file that can be modified to include references to this driver. If other games do this, then each game will need some work to get it working with this driver (i.e. it's unfortunately not plug and play).

Build / Usage instructions

Example build scripts are included for DOS (DOSBUILD.BAT) and Linux (unixbld.sh), but it could also be built on Windows without much additional effort (but at any rate, the driver itself is only useful on DOS!).

Essentially, the steps are:

• If building yourself:
  • Assemble the driver, drvsrc/hda16s.asm (with the -D?FLASHTEK option if targeting that DOS extender), as a binary (.BIN) file, using JWASM or similar.
  • Likewise assemble the detector, drvsrc/HDA16SD.ASM.
  • You can also build HMIAPPND if you have a C compiler handy (example build scripts are BOOTSTRP.BAT for DOS, using Open Watcom, and BOOTSTRP.SH for Linux, using GCC), but this isn't necessary as a DOS EXE of this patcher is included in the source repo.
• If not building yourself, you can grab a zip from the releases page, and extract the BIN files and HMIAPPND.EXE, but you'll still need to patch your games HMI*.386 files yourself.
• Use HMIAPPND to patch your game's HMIDRV.386 and HMIDET.386 files (syntax for this can be seen in the build scripts).
• To assist the detector in finding your hardware, it's advisable to set the environment variables HDA_BUS, HDA_DEVICE, HDA_FUNCTION, HDA_CODEC and HDA_WIDGET. Japheth's HDAUtils can help you enumerate your hardware and find the appropriate values for these. They should all be specified in hex without leading 0x or anything like that.
• If you want CD Audio to play through the driver, make sure SMARTDRV isn't running on your system.
  • The driver will not play CD Audio if it detects SMARTDRV. If it did, it would lead to buffer underflow and hence unpleasant crackling.
• If your game has an installer that detects the sound card which must be run from a CD (i.e. you can't directly modify its copy of HMIDET.386), you'll need to run HMIREDIR with the path to the directory containing your patched HMIDET.386. HMIREDIR should be assembled as a .BIN file and then renamed to HMIREDIR.COM to run it as a TSR.
  • There may be other complications with game installers, like custom file formats containing a list of sound cards (instead of just reading them from SOS itself). The RAYTOOLS folder contains source for another program to deal with one such binary format, and an EXAMPLE.BAT file showing how to deal with it for one particular Rayman game. Other Rayman iterations have text formats, and still others have built-in lists in the installer EXE itself.

Wishlist (for future versions / projects)

• Use EMS if available for CD Audio buffers
  • Right now, any game that hogs Conventional Memory can't play CD Audio through this driver at all.
  • Rayman Junior is an interesting case, in that I've found when EMM386.EXE is installed, I can play CD Audio with an 8-sector buffer, but this is simply impossible without an EMM.
• More tools for Rayman and for other games (possibly less invasive, command-line-based tools)
• Actually test the Flashtek version
• 8-bit / mono versions, for games / hardware that need those
• Similar drivers for other abstraction layers, e.g.
  • SOS 4 (as opposed to SOS 3, which this version supports)
  • MSS / AIL
• Support for pre-emphasis in CD Audio