The premise of tracking is that any given sound
sample can be played back at a speed in
KHz different than or equal to the speed in
KHz at which it was recorded. If I record a sample of someone tapping the middle-C key on a piano at 16
KHz, and then play it back at 15
KHz, you will get a note which is lower than middle-C. If I play it back at 17
KHz, you will get a note which is higher than middle-C.
To compose a musical work in a tracker, one first gathers all the sampled instruments one wishes to use for that particular composition. Then, notes are entered into patterns. A pattern is a set of rows - usually 16, 32, or 64 rows - which contain musical notes. You might create one pattern with an opening stanza, another with a certain musical phrase, etc.
A pattern may look like this (rather simplistic) example:
___________________________________________
| 1 | 2 | 3 | 4 |
|__________|__________|__________|__________|
|C-4 01 V80|C-3 02 V70|... .. ...|... .. ...|
|D#4 .. ...|C-3 .. ...|... .. ...|... .. ...|
|C-5 .. ...|C-3 .. ...|... .. ...|... .. ...|
|... .. V40|C-3 .. ...|... .. ...|... .. ...|
|C-5 .. V80|C-3 .. ...|... .. ...|... .. ...|
|... .. V40|C-3 .. ...|... .. ...|... .. ...|
|A#4 .. V80|C-3 .. ...|... .. ...|... .. ...|
|C-5 .. ...|C-3 .. ...|... .. ...|... .. ...|
|... .. V40|C-3 .. ...|... .. ...|... .. ...|
|G-4 .. V80|C-3 .. ...|... .. ...|... .. ...|
|A#4 .. ...|C-3 .. ...|... .. ...|... .. ...|
|... .. V40|C-3 .. ...|... .. ...|... .. ...|
|F-4 .. V80|C-3 .. ...|... .. ...|... .. ...|
|... .. V40|C-3 .. ...|... .. ...|... .. ...|
|D#4 .. V80|C-3 .. ...|... .. ...|... .. ...|
|... .. ...|C-3 .. ...|... .. ...|... .. ...|
|__________|__________|__________|__________|
In this example, which I have taken from an actual song I've composed, we have four channels allocated in this pattern. We're currently only using two. Each channel has space for a note (first column), a sample number (second column), and an effect (third column). In the first channel, I am playing a melody. I am playing the note C-4 with instrument 01 with effect V80. (That means set the volume to 80, which is maximum. Other effects might allow me to slide the note up or down at a certain speed, set the duration the note will be played, add a flange effect, or whatever else the tracker supports.) On the next row, I'm playing the note D#4. I'm not specifying an instrument or an effect; the tracker will simply assume I haven't changed my mind from the previous row and use the data there. I might only specify the sample and volume once in an entire song; the tracker will use these values all the way through.
In the second channel I'm playing a simple baseline with instrument 02 at volume 70.
When I've got all my patterns done, I can set them up in the pattern list, thus:
|001|
|002|
|001|
|002|
|003|
|004|
|003|
|004|
|005|
This will play pattern 1, then 2, then 1 again, then 2 again, then 3, 4, 3, 4, and finally 5.
Patterns are then played back in the order you specify to create the song. One pattern may be played back multiple times. This is especially useful for drums and baselines, which are often repetitive; you only have to create the pattern once, but you can play it back as many times as necessary.