Capo's primary selling feature is its ability to slow down your music without changing its pitch, or adjust its pitch without affecting the playback speed. You can modify these settings using the menu, the mouse, and your keyboard.
The Speed and Pitch settings share the same space in the main window, and you can switch between the two sets of controls using the mouse.
At any time, the pitch or speed can be controlled using the keyboard, regardless of whether the controls are displayed on the screen.
The playback speed control has 5 preset speeds, but you can adjust the playback rate to any value in between these presets.
By default, the scroller will snap to the preset values to allow you to easily choose the preset speeds using your mouse. If you wish to disable snapping, hold the shift key while dragging the slider.
Using the pitch controls, you can learn a song in a different key, transpose by entire octaves to hear bass lines more easily, etc.
For instance, Jimi Hendrix, Stevie Ray Vaughan, and John Mayer often tune their guitars down a half a step. Capo would allow you to play back the song a half a step higher, so you don't have to change the way your whole guitar is tuned.
Finely adjusting the pitch of a song is especially handy for recordings that may be out of tune. If you don't have a tunable instrument (harmonica, saxophone, digital piano), you can use Capo to correct the song to match your instrument's tuning.
Adjusting tuning finely is best done while using the looping feature, in a very short loop. See Looping for more information.
Note that beside the button titles, on the left, you'll find a set of small lights. When the lights are lit, that indicates the value is "dirty", or "not true."
For example, when the light beside the SPEED button is lit, the speed setting is not at the "true" value of 1x. Similarly, when the light beside PITCH is lit, the pitch adjustment is not zero, and the song is not playing at its "true" pitch.
In the screenshot above, you know the PITCH is not true, because the PITCH light is lit (and the slider is obviously not at 0), but you know that the song is playing at its normal speed, because the SPEED light is not lit.
These two small lights are very handy in Capo, because you can tell at a glance whether the song is playing in its true speed or pitch. When you load a Capo document, and you want to resume learning a song for which you modified the pitch, you will know right away.