The midi through midi9 entries in the Drivers32 part of the registry come up a lot, especially with certain brands of drivers such as Korg.
Location for 64-bit apps: Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Drivers32
Location for 32-bit apps: Computer\HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Windows NT\CurrentVersion\Drivers32
There are only ten of these entries, which is where the idea that Windows supports only ten MIDI devices comes from. It was never ten devices. It’s ten drivers that need an entry here.
Some tools, driver uninstallers and “MIDI port reordering” utilities break this location. A common example is creating a midi0 entry, when the first entry has to be named midi with no number.
With Windows MIDI Services, those tools can also remove the entries that make Windows MIDI Services work.
Windows MIDI Services doesn’t load drivers from the registry. It uses the two entries below and ignores the rest, so you no longer have to squeeze other drivers into the ten slots.
These entries are used in both the 32-bit and the 64-bit registry locations.
| Entry | Type | Value | Description |
|---|---|---|---|
midi |
String | wdmaud.drv |
Required for loading the in-box MIDI synthesizer |
midi1 |
String | wdmaud2.drv |
Hands the rest of enumeration over to the midisrv service |
These two are used only in the 64-bit location.
| Entry | Type | Value | Description |
|---|---|---|---|
MidisrvTransferComplete |
DWORD | 1 |
Tells AudioEndpointBuilder not to enumerate MIDI devices, because the Windows MIDI service handles that |
UseLegacyMidi |
String | 0 = use midisrv, 1 = use legacy, 2 = hybrid (not recommended) | Optional. Defaults to 0 when it isn’t there. |
The Registry page in the MIDI Troubleshooting and Repair app shows what’s actually there, marks anything that’s wrong, and repairs it for you. Windows has to be restarted afterwards, because the audio and MIDI services read these values when they start.
Windows MIDI Services is fully multi-client, and that was one of the main reasons to install a vendor driver for a device that’s already class-compliant. We recommend not installing third-party drivers unless you need them.
Windows MIDI Services is an open source project with all source available on GitHub. We have a great community on Discord as well. Between GitHub and Discord, you should find the information you are looking for.
