Well, let's see. I used to be a programmer so I will take a stab at this.
The Mix Engine is the code which scans all of the wave files i.e tracks you have recorded (lets stick with audio for a second, midi later) and then, because these are just digital bits of 1, and 0s, it adds them together into a two sided audio image, left and right. This left and right image is sent to your soundcard driver (another piece of software) which takes this stereo information and routes it into the chips of the card and ultimately to the output jacks and thus to your speakers.
The mix engine is a multiported environment with alternate inputs on each track for plug ins and midi input, as well as multiple output ports to other bussing groups or the main buss which once again sends things to the speakers.
The mix engine also has to take midi data and route it through software synths, an input output process and then combines this non-wave-file based data with the audio data, once again summing the whole thing and creating the final audio image.
So think of the Mix Engine as this multi armed creature taking input from all over the place, routing it and then sending to other input ports or output ports, then adding everything together in memory and creating a final stereo sound.
The Mix Engine then, is the code inside your sequencing software that does all this.
post edited by Middleman - 2005/09/15 23:45:20