Midi - trying to put it all together!

I'm getting more and more into working on symphonic music after years of mostly audio. I've purchased some orchestra libraries and I admit I'm having a lot of fun. And actually I'm pretty pleased with my progress. But I do have a few issues I'm trying to wrap my head around. The whole concept of velocity, volume and dynamics overall (with respect to midi) are still confusing. I have a session with about 30 tracks. Most of them I recorded one at a time (using mod wheel). Some I have copied and pasted from other tracks. And what happens is the dynamics get confused, I guess. It's like the velocity, CC 1, CC 11 (etc) all wind up telling the data to do something different. The result is the occasional note that will swing wildly in volume, or it will not crescendo like I want, etc. And then, if I use track view to edit, say, CC1 - it appears to be different than the data I see in PRV. And I realize that's kind of a big topic to answer in a thread. So - how much help would, say, one of the videos on the Cake store help me make sense of all of this? Can you recommend one in particular? Or - can you point me somewhere else that would help?

Hope I explained all of this well enough. Thanks!

Note to my comments above: I personally don't use CC 11 much unless it is required by certain patches (like certain ones in Hollywood). I just use Controller 7 and if I need to change the overall level, I use a Find/Change command to increase or decrease the values. But what I said above is what most people do and is much easier—I am just stuck in my old habits.

It's important to understand that different sample libraries respond to different controllers in different ways. Where Garritan uses mod wheel for volume, others use it for vibrato, for example. That may explain the discrepancies you're experiencing. Velocity refers to how hard the key is struck, literally how fast the key moves past a sensor that computes its actual velocity. This parameter is usually mapped to how loud the instrument appears to sound or which sample layer is triggered. Volume refers to the overall volume of whatever's going on with that particular MIDI channel. For example, it's possible to have a velocity of 127 (a drummer banging away at full force), but a volume of 10 (the volume is turned down to blend in with the mix). Does that explain things any better? Not all sample libraries are created equal, nor are they programmed the same way. You'll really have to delve into your documentation to get the most out of each library.

Select the track with the confusing data. Press Alt-4 to launch the Event List. In this list you will see all notes, controllers, volume changes, mod wheel data, CC's etc. so you can figure out what the mystery controllers/MIDI events are. 
  
Note that controllers drawn in the PRV or recorded directly will not show up in automation envelopes just as data from automation envelopes doesn't show up in the PRV but they -all- show up in the Event list.
 
As Konrad says, also note that velocity affects "dynamics" and timbre and volume doesn't. As you know a cello sounds different bowed softly (low velocity) versus bowed hard (high velocity). Different velocities will trigger different samples whereas volume simply affects volume. A loud velocity with a lower volume will sound completely different than a soft velocity with a loud volume even though both may register the same in dB on a meter. Use velocity to control the timbre and expression of an instrument and volume to control volume.

I'll chip in my two pence here, I think...

Admittedly, I may not a "complete" expert with all things Sonar, but I do come from a MIDI background and have been creating MIDI music for over twenty years. Plus, my main area of expertise is in the use of non-sample based synthesizers. 

In the old days, before Sonar, and before mixing consoles come into being, I would control everything via MIDI messages, either at the beginning of a track, or at any point through the track. So I am no stranger to MIDI.

As has been mentioned here already, Velocity determines how hard an instrument is played, generally. And I say generally, because each instrument is different. Especially instruments that use multi-layered sample sets. I have always used Velocity to represent expression, although, with synths, the velocity messages act on the sound in a different way to sample based players.


I rambling a bit there, and what I really wanted to add here is, that I no longer use the Volume MIDI controller any more, and I rely solely on the sliders in the mixing console to get each MIDI performance to fit into the mix. If I need to alter the volume during a performance I will then use an envelope on the track, rather than adding MIDI controller messages. I find it easier that way nowadays, and I rarely use Event List (which is where I would add such messages) any more.

Anyway, that was just my opinion, and there is always more than one way to skin the proverbial cat...