bc1 wrote:
midi's no good for this. if i were working with drums sounds, or with organ or piano or something like that, midi would be fine, but mixing live horns with fake ones just sounds awful.
Sorry, I don't think I explained myself too well before. I would agree that a mixture of synth horns and live would sound pretty terrible (in fact in my opinion synth horns are best avoided all together - I've only ever heard a couple of people make them sound any good and I'm not one of them!). But MIDI is a lot more flexible than its generally given credit for. Perhaps by describing a couple of ways I've used it to do similar things to what you're after I'll be able to clarify myself.
The setup that sounds closest to what you're after is the one I mentioned before, using Ableton Live and a MIDI footswitch. I don't know if you're familiar with Live but one of the main uses of the software is to create songs on the fly by layering up various loops. You have a number of channels (similar to Cubase etc) and these are all split into banks. The banks allow you to change a whole set of loops simultaneously (obvious example being switching from a verse to a chorus). I can configure the footswitch so that it allows me to select a bank to record into, arm a channel, begin recording, end recording and start looping all without having to stop playing. So typically I'll start by beatboxing a beat and getting that looped up. Then its usually the bass line followed by whatever other toys I have to hand
All the sounds are actual instruments tho, I rarely use any synth sounds at all. Coming from a jazz and blues background myself, I also tend to have a couple of spare channels set up to monitor each of the instruments so I can solo or just add some little bits of lead to whatever is going on at the time.
Whilst the footswitch isn't essential for this to work, it means that I can keep playing the whole time without having to stop and fiddle with the computer. Otherwise the tracks tend to get very long-winded and drawn out. Its very similar to using one of the Line 6 loop boxes however its a lot more flexible as you still have control over each of the individual loops at all times. As mentioned before, you can also switch between whole sets of loops simultaneously. I tend to also use MIDI to map my control surface to the Ableton controls so I can do hip-hop style drop-outs (mute everything apart from one or two instruments for a couple of beats then drop it all back in together) and also have hands on control for effects such as filters or delays.
Another side benefit of using Ableton and the PC is that once you're done playing you have the option to save everything so if you only want to re-record some of the loops live, you can start from a track you've already configured. Very useful if you want to start a track with multiple instruments rather than having to build everything up layer by layer each time.
The obvious disadvantage of all this tho is that you'd need to take almost an entire studio to each gig! As a result, I've only ever used the full setup in the studio although we also use a similar set up in one of my bands to play pre-recorded samples over the top of everything else, again with Ableton Live as the software.
Another simpler alternative that has just occurred to me, again using MIDI and a footswitch, would be to use some software that will map MIDI commands to PC Keyboard commands. You mention that something like RealPlayer would suffice. If I remember correctly, pressing the space bar in RealPlayer will start / stop playback. So you can setup up the software so that whenever it receives the MIDI signal from the footswitch, it sends a message to RealPlayer simulating the space bar being pressed. Thus you can start and stop RealPlayer using the footswitch. I used to have some really good software that did just what you need (I remember being mildly amused for a while by controlling windows using my control surface!) but I can't remember the name of it. Having just spent a little while google searching the best I can find is called GlovePIE which is available at
http://carl.kenner.googlepages.com/glovepie . It looks a bit trickier to configure than what I had before but I think it can do what you need
I hope all this is of some use and I haven't completely missed the point of what you're trying to do!!