About Multimedia Timers
Multimedia timer services allow applications to schedule timer events with the greatest resolution (or accuracy) possible for the hardware platform. These multimedia timer services allow you to schedule timer events at a higher resolution than other timer services.
These timer services are useful for applications that demand high-resolution timing. For example, a MIDI sequencer requires a high-resolution timer because it must maintain the pace of MIDI events within a resolution of 1 millisecond.
Applications that do not use high-resolution timing should use the SetTimer function instead of multimedia timer services. The timer services provided by SetTimer post WM_TIMER messages to a message queue, while the multimedia timer services call a callback function. Applications that want a waitable timer should use the CreateWaitableTimer function.