When you’re trying to synchronize musical events to a timeline, it’s sometimes useful to have a metronome that tells you where the computer thinks the beat is. The metronome makes a percussive sound on each beat, and ideally makes a unique sound on the first beat of each measure. Most DAW and MIDI sequencing programs have such a feature.
The easiest way to establish MIDI connection between Max and other applications on the same computer is via the "virtual" MIDI ports Max provides. Max creates two virtual input ports and two virtual output ports that can be accessed by other MIDI applications. (You can see those virtual ports listed in Max's MIDI Setup, by choosing MIDI Setup... from the Options menu.)
The left part of this example shows the use of the random object to make arbitrary note choices. Every time random receives a bang in its inlet, it sends out a randomly chosen number from 0 to one less than its argument. In this case it chooses one of 61 possible key numbers, sending out a number from 0 to 60. We then use a + object to offset that value by 36 semitones, transposing up three octaves to the range 36 to 96––cello low C to flute high C.
The line object interpolates linearly from its current value to some new destination value, ramping over a specified period of time, reporting its intermediate values along the way. In this example, we instruct line to ramp toward a given destination value, arriving there in 2 seconds, sending out a report of its progress (the intermediate values as it goes toward the destination) 12 times per second (i.e., once every 83.333 milliseconds).
There are many objects available for delaying events (i.e., for scheduling events to happen at a specific future moment). For timing and scheduling events, the most common object is the metro object (send bang periodically at a specified time interval), which can be used to trigger events, start/stop entire processes, or trigger a counter to step through a table or a coll or any sort of sequence of things.
Here are three ways of generating MIDI notes. Admittedly they don't result in very interesting music, but they show ways how numbers can be converted for usage as pitch information.
The timepoint object sends out a bang when the transport reaches a specified time position. This can be useful for causing something to happen—or for starting an entire process—at a particular instant during the transport's progress. A timepoint might, for example, even trigger a new time position value to be sent to the transport object itself, thus causing the transport to leap to a different time.
The line object sends out a periodic series of numbers that progress to some new value over a certain amount of time. The input to line is a destination value (where it should eventually arrive), a transition time (how long it should take to get there), and a time interval between outputs (how often it should send out intermediate values along the way). The left part of this patch shows the use of line to generate integers that are used as pitches.
This program shows the formula for linear mapping of one range to another, and implements the formula using basic Max math objects. One can use the objects zmap and scale to do this task more simply, but this example demonstrates the formula explicitly.
This patch demonstrates the two simplest objects for generating random numbers. Every time it receives a bang in its left inlet, the random object generates a random integer in the range from 0 to one less than its argument. (For example, if you tell it to generate one of 12 random numbers, it will choose a number from 0 through 11 inclusive.) Note that this includes the possibility that successive random choices may appear to generate what seem to be patterns, especially if it's choosing from among a small range of possibilities.