[sdiy] MIDI volume to volts formula

[rsdio at audiobanshee.com]

It took a month before I got started on a MIDI Velocity histogram app, but only a couple of hours to actually write it (thanks to CoreMIDI, etc).

I’ve only done a quick test with an Ensoniq VFX set to the defaults, so I’ll need to spend more time with other keyboards as well as looking into the velocity curve settings options.

With the VFX, I’m only seeing 45 unique velocity levels (not counting 0, of course). The VFX reaches up to velocity 127, as well as 126, 125, 124, and 123, but then there are gaps between the remaining velocity values at 120 and below.

Based on your description, the DX7 only implemented 5-bit velocity instead of the full 7 bits.

Brian


On Jun 7, 2018, at 8:02 PM, MTG <grant at musictechnologiesgroup.com> wrote:
> If you are lucky. The DX7, for instance, divided the incoming velocity by 4 and only dealt with 32 values each way (over MIDI). Spread over the whole range obviously. I'm sure some more modern synths have the complete range, at least this original "low resolution" version. We await your histograms Brian.
> 
> On 6/7/2018 7:28 PM, rsdio at audiobanshee.com wrote:
>> On a related note, when mapping an input range of 128 values to an output range of 128 values, the only function that actually produces 128 unique values is the linear 1:1 mapping. This assumes we’re not using real, floating point numbers because MIDI is discrete integer values. Every other map or curve will not actually produce 127 different velocity values on output.
>> Perhaps Yamaha decided to use a curve that would have only produced 100 distinct outputs anyway.