[sdiy] Tips for writing a MIDI parser wanted

[Richard Wentk]

On 25 Mar 2009, at 18:32, Ingo Debus wrote:

>
> Am 24.03.2009 um 21:13 schrieb ASSI:
>
>> On Dienstag, 24. März 2009, Ingo Debus wrote:
>>> But only if an active sensing msg has been received recently - many
>>> MIDI devices don't send active sensing at all. You'd be shutting
>>> off the notes all the time.
>>
>> The MIDI spec says that active sensing is to be activated if you have
>> been receiving at least one active sense byte and no provision is  
>> made
>> to switch it off based on the reception (or not) of further active
>> sensing events.  You would have to receive a system reset to  
>> revert to
>> default state
>
> You mean, once a active sensing message has been received, notes  
> have always to be shut off when no more active sensings are coming in?
>
> This seems a bit problematic to me. Imagine someone hooks a  
> keyboard that is sending active sensing messages to a synth, then  
> switches to another keyboard (either by hot-plugging or by a MIDI  
> switch) that doesn't. It just wouldn't work. Since most musicians  
> aren't MIDI wizards they surely would think either their synth or  
> their keyboard had gone bad.

No, that's exactly the point. If a MIDI lead is disconnected, all the  
notes turn off to prevent MIDI drone. This makes sense because on  
some keyboards there's literally no way to turn off MIDI drone  
without cycling the power.

MIDI doesn't use hot plugging or switching - most people use a MIDI  
merger box or a thru chain.

And where they do use a switch, there aren't going to be many  
situtations where you're going to want to hold notes after switching.

Obviously this doesn't mean you can't still play notes from the  
keyboard. It's only MIDI notes that are playing which are shut off.

Richard