Rondo 1.2 ($25), from fracturedSoftware, is a MIDI-file player for Mac OS X. Rondo automatically routes MIDI playback to the QuickTime Music Synthesizer, which is GeneralMIDI — compliant, but you can also choose any MIDI port that has been enabled in OS X's Audio MIDI Setup utility. For example, you can use an IAC port to route playback to other running MIDI applications, such as standalone virtual instruments or DAWs running instrument plug-ins. But Rondo's main purpose is to quickly audition MIDI files, and QuickTime is fine for that.
Using Rondo is simple: you load a Standard MIDI File and press Play. Notes are displayed in a vertically scrolling piano roll, which makes it much easier to analyze what's going on than the more common horizontally scrolling variety does. The notes, which are color coded by track, pass under a movable play head with a resizable piano-keyboard graphic that animates its keys with the track colors as notes pass underneath. Individual tracks can be muted or soloed so that you see and hear only the parts you want. The visual feedback, together with the ability to slow down the tempo, makes it easy to analyze the parts being heard.
To further aid in analysis, Rondo provides playback start and end markers. Playback can be set to loop between the markers, play the marked region once, or simply jump back to the start marker each time you initiate playback. In an interesting twist, columns (including the piano roll) can be duplicated, and they have independent display settings. For example, you can display a piano part on one piano roll and a bass part on another, or have the Velocity column display only drum-track Velocities.
Rondo is not a file editor, and there's no save function, which would be convenient for saving different Rondo setups. But for quickly auditioning MIDI files on either the QuickTime synth or one of your own virtual instruments, Rondo is a useful tool and is well worth taking a visit to the fracturedSoftware Web site (www.fracturedsoftware.com).