I think this form of automation is the easiest to work with.
Tom's idea with having n tracks record the volume changes is excellent, but your cpu needs to be a powerhouse.
Its really not that hard to do it the regular way, you just have to understand how it works. First bring up your volume envelopes. Youll see a line that is inserted in the middle of each tracks waveform. Think of this line as your fader now. Instead of having to move the fader by hand, you will tell the computer to do it for you.
a standing line in the middle of the waveform indicates no change in volume. If it falls below the middle, you are cutting the volume, likewise if it rises above you are boosting the volume level. recognizing how the wave looks cooresponding to the song is crucial. Watching the wave and its parts as the song plays will give you an idea of where you should be boosting or cutting.
when you have decided where you would like to insert your volume change, for example, a 3 second electric guitar riff in a song that should stand out a bit more, you need to apply the nodes that will control the change. this is a bit complicated because moving nodes can make the whole level of the whole track, but if placed correctly, you will have no problem. A general rule to get started with placing nodes: first target the section of the waveform you are going to apply the envelope to. Then what you want to do is place a node on each side of this section of the wave part. Zoom in as close as possible to ensure you are placing the node as close to where the sound starts and ends. Next you are going to place two more nodes next to each of the ones you just placed, on the outside of it. Then from there you adjust the two sets of inner nodes to fit the volume you are hoping for, and the rest of the wave will not be affected.
XVXVX XVXVXVXVXVXV XVXVXV
if this was your various waveforms in the song--- and you want to apply volume autmoation to the middle section and not the two outside sections...here is how the nodes will look.
XVXVX . . XVXVXVXVXVXV . . XVXVXV
notice the periods indicate where you placed the nodes. remember that you should only move the inner nodes for the volume change. ****The outer nodes should only be moved to adjust how quickly or slowly the volume boost occurs. For example, having the outer set of nodes close to the inner set will cause a quick change, while having them further apart will denote a slower change aka.. a fade.
This probably seems a bit confusing but, once you play with it, it becomes no sweat.. just fool with it a bit. hope this helps,
Luke