# Topic: Exactly what does velocity do?

1. ## Exactly what does velocity do?

Exactly what does velocity control?
People say that you should keep the mod and velocity parallel, but the lower velocities have a very intimate, slow attack. What if I want an intense pp?

I don't understand what velocity actually does and why people say it should be parallel with the mod values.

-Chris

2. ## Re: Exactly what does velocity do?

There is no reason to make them parallel, unless that's the effect you want. Velocity controls the strength of the attack, and there is a reason the controls are seperate.

For example, imagine a woodwind instrument playing a solo melody. The melody is marked piano, so he plays softly. The part he's reading from may contain all sorts of different tonguing and phrasing. There may be accented notes, and sharp staccatos... all of this within the same phrase marked piano.

My suggestion is to first use the mod wheel to get the proper dynamics. Then when it feels more or less correct with the dynamics, view all your velocities, and adjust accordingly.

3. ## Re: Exactly what does velocity do?

Thanks, Skysaw.

But do you know how the velocity affects the sample? Or if there is a seperate set of samples recorded at different attack stregnths?

-Chris

4. ## Re: Exactly what does velocity do?

I believe that one of the primary functions of velocity is to control the attack of a sample. With brass, for example, the tonguing will be more pronounced at higher velocity. I believe this is accomplished by ramping in the attack of the sample slower at low velocities rather than using separate samples (which is why GPO can still fit into 1MB RAM!)

I imagine Tom will swoop in and give the full story.

- m

5. ## Re: Exactly what does velocity do?

Originally Posted by Markleford
I imagine Tom will swoop in and give the full story.
I never swoop in until after noon PDT, the beginning of my day! I swoop so much better after breakfast.

OK, velocity. What I'm about to say applies to the "Expressive" instruments in the library (mostly strings and winds.) "Percussive" instruments like piano, pizzicato strings, and percussion use velocity in its standard function - velocity=volume or, often, velocity=volume/timbre.

In winds and solo strings velocity does indeed control attack strength. Low velocities give gentle attack slopes, higher velocities give faster attack slopes. Very high velocities give accented attacks. This is all accomplished using a combination of envelopes (not separate samples). A "flex" envelope is used to supply emphasis at the highest velocities.

In section strings (Sus+Short), short bow samples, tied to velocity, are layered with the long bow samples. As you use higher velocities you hear more of the short bow contribution.

I'm not sure where the idea got started that mod wheel and velocity should have parallel values. Nothing could be further from the truth. They should be approached as completely independent controllers as described by Jamie above. To which I would add one other (independent) controller: cc#21, length control. With mod wheel, velocity, and length control the user has the tools to create a wide variety of note lengths, attack strengths, and dynamic volume/timbre changes. You can create loud, long notes with gentle attacks; loud, long notes with accented attacks; soft, short notes with sharp attacks; soft, short notes with gentle attacks; or anything in between. Length control at its lowest value settings, especially with strings, affects one's perception of attack character. Micro-managing your mod wheel can help you create "fp" and "sfz" effects, as well. Of course, actual MIDI note length comes strongly into play here too. That about covers it.

Anyway, use the controllers independently and experiment. Along with some of the "Ag" instruments (with controller cc#16) for the most aggressive effects you should be able to cover a rather large area of attack and articulation types.

Tom

6. ## Re: Exactly what does velocity do?

Thank you very much, Tom!

-Chris

7. ## Re: Exactly what does velocity do?

Originally Posted by Tom Hopkins
I'm not sure where the idea got started that mod wheel and velocity should have parallel values.
I imagine that this comes from the MIDI File Translator utility, which does the *opposite* for "standard" orchestral scores for traditional MIDI playback: converting velocity to CC#1 values so that GPO alters volume accordingly.

- m

8. ## Re: Exactly what does velocity do?

Originally Posted by Markleford
I imagine that this comes from the MIDI File Translator utility, which does the *opposite* for "standard" orchestral scores for traditional MIDI playback: converting velocity to CC#1 values so that GPO alters volume accordingly.
Interesting connection. That hadn't occurred to me.

Tom

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