MIDI Programming: Velocity vs. Expression

[como baila]

I understand that there are velocity sensitive instruments,i.e., samplers, synths, etc., in which different velocity levels trigger different/ additional samples or other linked CC. I also understand when recording midi performance, velocity is the 'dynamic' parameter.

But other than that, can anyone give me a coherent explanation of the whys and why fors of using velocity versus expression when programming midi files with respect to dynamics?

Thank you.

Prado

[lfm]

Final volume of a note is CC#07(volume)+CC#11(expression)+velocity on the note.

It's not just added, it becomes some average value kind of since 127 is max.

To program I would not bother with expression. Use expression when live recording only.

Expression and modulation wheel often change the timbre of the sound as well, so that's another parameter.

[como baila]

Thanks ...

I guess I can generally forget about it then ... although I can imagine it could be useful for a fade in or fade out against an existing midi note passage. Someone else suggested to me that whereas once a 'note on' message is triggered, the initial velocity remains the same until a 'note off' message, expression is a continuous event. This would mean against a sustaining sound, like an organ or sustaining string chords you could draw long notes and use expression to modulate the sound louder then softer, etc. It might be easier than having to program multiple legato notes for the same effect.

I think I'd rather try that out than mess with the volume of the synth/ module and inadvertently forget and leave it at some less than optimal level.

Como

[petelina]

AUTO-ADMIN: Non-MP3, WAV, OGG, SoundCloud, YouTube, Vimeo, Twitter and Facebook links in this post have been protected automatically. Once the member reaches 5 posts the links will function as normal.

In addition to @lfm 's formula Volume (07) + Expression (11) + NOTE velocity, it is important to mention that even though both Volume and Expression are "continuous" controllers, Expression, CC11, is the only control that can modulate a "single" note's loudness (or whatever the "vertical" set of Note events at Expression event time is).

Graphically, something like

Code: Select all (#)

N = note
V = Volume (CC7)
E = Expression (CC11)
v = note velocity

     +++++++++++++++
CC11 + EEEEEEEEEEE +
     +-------------+
CC07 + V.......... +
     +-------------+
NN   + N.......... +
vv   + v.......... +
     +++++++++++++++

[jamcat]

In physically modeled instruments like SWAM strings/woodwinds/brass, expression is used to continuously control sustained bow/breath intensity. You couldn’t do that with velocity or volume.