Re: [Audacity-devel] MIDI Volume

[Federico M. <fm...@fc...>]

Adrian,

MIDI volume is not the same as gain control (even if both may have the 
same result). Gain control is a mixer concept and volume a MIDI concept.

For example, you might have a synthesizer which has been sent a volume 
message for MIDI channel 4 and its analog output is routed through 
mixer's channel 6. Then the gain control through mixer's channel 6 fader 
affects all MIDI channels, each of which will be affected also, and 
multiplicatively, by its own volume.

Now, if you split a MIDI channel over different tracks, but it remains 
the same instrument, then the last volume message is the one that holds 
until a new one arrives. This is dangerous, because a volume increment 
sent on track 1 through which messages for channel 4 are sent will 
impact on channel 4 going also through track 2.

It will also be complicated if a note on comes for channel 4 through 
track 1 for MIDI pitch 60 and then a note off comes for the very same 
channel 4 through track 2 an the same note, then the note coming through 
track 1 will stop.

In my opinion, different Audacity tracks should not be allowed to route 
the same channel of the same instrument. But we might have two different 
instruments, whose channels would be associated with a number of tracks, 
at most 16 each. For instance, channels 1 - 16 of the first instrument 
could be associated with Audacity tracks 1 - 16, and tracks 1 - 16 of 
the second instrument could be associated with tracks Audacity 17 - 32. 
When a volume change for channel 4 of instrument 1 is intended, only 
track 4 would contain the message. Track 16 (channel 4 of the second 
instrument) would have no volume message.

Regards,

Federico


On 30/10/2014 16:57, Adrian Wadey wrote:
>
>
> On Oct 30, 2014 7:30 PM, "Roger Dannenberg" <rb...@cs... 
> <mailto:rb...@cs...>> wrote:
> >
> > By gain, I assume you mean MIDI's Volume control. Volume control can 
> only be applied to a MIDI channel, not to individual notes or tracks. 
> Thus, if there are two Audacity note tracks and each has MIDI notes on 
> channel 4, then gain controls for the two Audacity note tracks will 
> not be independent. How do you propose dealing with this problem?
> >
> > -Roger
> >
> A good point that I hadn't considered.
> First thoughts:
> Users should avoid doing this as there are other problems (program 
> change, other controllers). It may be acceptable to highlight the 
> problem and let the user address it.
>
> Combine the two gains.
>
> Render the MIDI using multiple synthesizers.
>
> Support multiple MIDI interfaces.
>
> Do you think velocity is the best compromise?
>
> Adrian
>
>
>
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