MIDI performance

These perception limits make it possible to manage MIDI timing performance by quantizing the MIDI data--grouping MIDI messages and sending the groups at specified intervals. Quantizing the data helps prevent MIDI playback from dragging. It also helps prevent the MIDI system from placing too large a load on the CPU.

NOTE Quantizing MIDI data meters the load that the MIDI system puts on the processor. Think of a metered on-ramp to the freeway--by allowing one or two cars onto the freeway at timed intervals, the overall traffic flow is maximized. In the same way that metered ramps help prevent gridlock, quantizing MIDI data helps prevent the MIDI data from overloading the system.

You use TMIDIPlayer::SetQuantum to quantize MIDI data. For example, since 10 ms timing differences are virtually imperceptible, you can quantize the data at 10 ms intervals. If you quantize the MIDI messages A, B, and C in Figure 32 this way, message A occurs at 10 ms, and B and C both occur at 20 ms. To the listener, the difference is imperceptible.