How many MIDI channels do I actually have? Are they categorised?

**pish_flaps** · 05-10-2012

OK, I'll start by saying that I'm aware this particular rabbit-hole goes pretty deep! So please don't just link me to a page explaining everything about MIDI! It's a specific problem I have, and I already have a very basic understanding of what MIDI is. However, if I'm really being a dumbass and expecting everything on a plate when alot more research is needed, please don't hesitate to tell me so!

My question is this: I have a 49-key MIDI controller (MPK49) which has, in theory, over 150 separate MIDI inputs. But can I use them in reality to control over 150 different things? And if so, how would I go about setting this up in Ableton Live 8?

My keyboard has:

12 MPC drum pads, each with four "banks", so 48 controls there.
49 keys
8 faders (x3 banks)
8 buttons (x3 banks)
8 knobs (x3 banks)

= 169 MIDI controls

The way the keyboard looks, you'd think it would be easy-ish to set up the drum pads to do one thing and the keys to do another, but I've come to understand that no matter what the input looks like, it sends the same signals, whether it's a key/pad/fader etc, so the software can't tell the difference. But how come moving faders never interferes with playing the keys, while pressing the drum pads will play a key when I don't want it to? Can I assign the pads to a different "section" of MIDI where it won't interrupt it?

I'm boring myself now, so good luck if you made it this far, and props if you can be of any help!

Eddie

**krushing** · 05-10-2012

Well, first of all...a single MIDI control isn't a MIDI channel. The keyboard sends all the controls on one of the 16 available MIDI channels (one MIDI port = 16 channels). And then there are different types of MIDI messages, which roughly break down to note on/off events, program changes, controller changes & sysex (which is channel independent). So to some extent, the software can tell the difference

Lastly, I'm gonna do what you didn't want me to do and provide a link to a list of possible MIDI messages, just so you get a feel on what's going on under the hood. Theoretically you should be able to assign any control to send out any kind of messages, but in reality this might be restricted a bit, just so it doesn't get too confusing - you rarely need to send note on/off messages from a fader (but occasionally you just might want to), for example.

**bandcoach** · 05-11-2012

Yep....

MIDI is about a bunch of different control structures.

They chose to limit what they could do as there was no inkling back in 1982 just how far computers would progress, nor whether MIDI would survive its initial versioning.

As a result everything is a 7 bit message with an error checking bit.

Pitch has 128 notes: 0-127 C-2 to G8.
Velocity is 0 - 127 and is meant to be a representation of the physical forces at play in playing a key or other control device. Velocity is a vector; it has speed and direction - the physical correlation is that if you move something faster onto a string {the original target of pianos}, it will sound louder and so on down to it not sounding at all {I can play like that, but it takes it great patience to master it}.
Duration is a collection of 7 bit messages. One to start the sound, one to finish the sound. Some sequencers use a velocity message instead set to 0.
16 channels comes from having a 4 bit number: it can range from 0 to 15 which is 16 separate states.
Controller messages are well catalogued but there are only 128 controllers per MIDI channel. This still means that there are 16 (2⁴) X 128 (2⁷) controller messages => 2048 (2¹¹) controller messages in total.

Some software is specifically written to allow a hardware controller to use these messages to control every parameter of a DAWs channel processing capabilities. I have the TASCAM US2400 which is a USB mix surface, very nice, very easy to use and great control of channel parameters once the mapping is set up.......

**krushing** · 05-11-2012

And of course, MIDI's very limited bandwidth is gonna run out way sooner than you'll run out of controls, if you're sending a bunch at the same time.

**bandcoach** · 05-11-2012

Exactly.....

**pish_flaps** · 05-11-2012

Thanks everyone, especially krushing and bandcoach! Turned out that to sort my problem I just needed to read up a little bit about MIDI channels. Still don't understand all about MIDI but I'll worry about the rest later!