[LAD] "Open midi-keyboard"

Ralf Mardorf ralf.mardorf at alice-dsl.net
Sat Sep 26 12:03:48 UTC 2009

Rui Nuno Capela wrote:
> Ralf Mardorf wrote:
>> Christian wrote:
>>> For the keys I love aftertouch :)
>> An option that can regulate the number of the aftertouch events that are 
>> send is useful. Some sequencers have an option to reduce the amount of 
>> recorded aftertouch events, but not every sequencer is able to do it. 
>> Using aftertouch sometimes produce too many unneeded data, that can 
>> become a problem.
> talking about aftertouch (aka key-pressure), there's two different
> kinds: "channel aftertouch" (independent of key/pitch) and "polyphonic
> aftertouch" (per key/pitch). the later is seldom implemented but it
> might give an edge on this "open-source midi keyboard" project. it also
> generates a greater amount of events as Ralf warns about
> cheers

I never had a keyboard supporting "poly pressure" ($An), they only 
supported "channel pressure" ($Dn), n is for the channel.

Even the common "channel pressure" for some keyboards can cause a lot of 
unneeded data, while played by keyboarders with shaky fingers ;).

Let's say you want to reach an aftertouch level of 120 ($78), this can 
result in a huge amount of $Dn $78, $Dn $77, $Dn $79 etc., running 
status won't reduce a lot of bytes, while there will be data for other 
channels on the same MIDI port.

Another point is, at what value aftertouch should start with level 1. 
Internal a keyboard there should be a resolution of more than 127 steps. 
There should be settings that start aftertouch at soft pressure and 
other settings to start aftertouch at hard pressure.

When using several MIDI ports even a lot of SysEx can be sent real-time, 
but using only one MIDI port even aftertouch can cause timing problems. 
It would be good if there would be some features for the master 
keyboard, instead of using filters or editing functions by a sequencer.


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