[richiebee]

Sysex is not intended to be used to send short data chunks like volume changes or patch changes, nor is it intended for real time performance. It is usually used to send messages for a specific device (hence the name SYStem EXclusive, which is where SYSEX comes from) and because it usually contains a lot of information, gets broadcast at the start of your MIDI file rather than during it, when it can cause hiccups in the data flow.

Patch changes have their own handler (Program Change), and Volume, Pan etc have their own handlers (both Control Change messages... 7 and 10 respectively).

MIDI has several levels of specifications (MIDI, General MIDI, GS, XG). It's important to understand where your sound sources fit into this. GM is the most basic standard, but is also the most restrictive. It's way too restrictive for really serious sequencing, but does the job for creating really widely compatible files. GS is Roland specific and XG is Yamaha specific. Neither one is really widely used because they cease to have the advantage of General MIDI compatibility, and are still restrictive.

Most of our realistic sound sources these days are way too complicated to follow such a tightly defined specification such as GM, GS or XG. Luckily, these days, if you stay in the box, recalling patches in your sound sources is easy. It wasn't always this way!!!