DirectMusic is part of Microsoft's DirectX technology which was developped to ensure faster hardware access to peripheral devices like graphiccards, soundcards, joysticks and also MIDI devices. DirectMusic replaces the older MIDI functions of the Windows MultiMedia system, generally called MME which stands for Multi Media Extensions.

Both DirectMusic and MME offer sets of functions to application developers that they can use to add MIDI handling to their applications. MME has been around since before Windows 95 came to market. It is still used by the majority of MIDI applications available today. DirectMusic is of more recent date. It has some extra features and technological advancements compared to MME. In order to use these new features MIDI devices need new drivers.



 Most manufacturers of MIDI equipment provide DirectMusic capable drivers nowadays so application developers have the choice between MME or DirectMusic to add MIDI functionality to their programs. Both technologies are compatible with each other. MME applications can use DirectMusic MIDI devices and DirectMusic applications can use non-DirectMusic MIDI devices. Non-DirectMusic MIDI devices will appear as emulated MIDI ports to DirectMusic applications. True DirectMusic MIDI devices will appear as both a DirectMusic port as well as an emulated DirectMusic port. The emulated port in this case will be the one that MME applications can use. If you have the choice you should always choose the non-emulated ports. The emulation mode adds about 5 to 7 milliseconds of latency to the MIDI processing.

Although DirectMusic ports can be used by MME applications and DirectMusic applications can use non-DirectMusic ports, the benefits of DirectMusic will only be available if you have both a DirectMusic application as well as a DirectMusic driver.



 One of the biggest benefits of DirectMusic drivers is the timestamping of MIDI input. In the Windows MultiMedia system, time related MIDI input data is handled by the receiving application itself. Applications on Windows 2000 and XP always run in so-called user mode. Most of the hardware handling on the other hand, takes place in so-called kernel mode. Kernel mode processing takes priority over processes running in user mode. In practice this means that if another hardware device needs processing time at the time of delivery of the MIDI input, the MME application will just have to wait. Depending on the hardware device in question, the wait time can be considerable.


 This results in MIDI input arriving late and, more importantly, variations in the delivery time of MIDI data from hardware to application. This effect is sometimes called MIDI timing jitter. DirectMusic solves this problem by timestamping the input data at the moment of arrival to a system wide reference clock. This timestamping takes place in kernel mode and thus has high priority. The DirectMusic application still runs in user mode but this time, when it receives it's input data, it already has an accurate timestamp.


 The result of all this is that DirectMusic applications have more accurate MIDI recording capabilities. They will suffer much less from jitter in timing.


 One important question remains to be answered: How many applications use this marvelous new technology? At this moment the number is small but my expectation is that more applications will see the benefits of DirectMusic and will incorporate it in the future. Steinberg's Cubase SX is one of the applications that already made the crossing. A lot of users, me being one of them, are enthousiastic about this great program.