Hi Ben
>I've read the pdf doc and understand a lot of it, but I don't
understand the need for the "base" channels.
1)"Basic channels" is a MIDI specification.In short this allows to
split the whole set of synthesizer channels in distinct MIDI channels
groups.
Each group is composed of continus MIDI channels starting from the
first called "Basic Channel".
Each group can be set in different mode via MIDI CCs (Polyphonic,Mono,
OmniOn,OmniOff) that have to be send to the Basic Channel.
>Does it mean you need less cpu to run Fluidsynth?.No, assuming no
reverb, no chorus, cpu usage is hightly related to the number of a
voice a simple note need.
For example on RPi2 Fluidsynth (using the 4 cores) can plays 180
voices maximum.(note that a "voice" in FluidSynth spelling is what is
called an "Instrument Zone" in SF2.1)
Assuming the patch applied, by default a FluidSynth instance have a
default Basic Channel number 0, Poly, Omni On. That mean that
this instance is ready to play on 16 MIDI channels (the default
channel settings), in Polyphonic.
2) So in this state the FluidSynth instance plays polyphonically on
each channels.
If a CC legato On is send to a channel, this one switchs from
polyphonic to monophonic and behave monophonically.
This is a MIDI behavior specifications. This is a real-time Poly/mono
control of a MIDI channels.
On a MIDI channel in the monophonic state, the "legato playing" manner
works , but with serious limitations (discuted in the pdf).
3)>How do I test this patch? Download the latest git and re-compile?
Add the patch somehow?
You cannot download the latest git until the patch will be accepted
and committed .
You need to apply this patch by your own on your actual source version
(1.1.6). The manner depends on the platform you works.
I am not an expert in patch, i don't know how to do but, i wish that
it isn't complicated to do.
I hope this post will be read by a developer who practice the
procedure and can describe it.
Note that apart the patch file that adds functionality to existing
file (fluid_synth.c, ...), there are 2
new files (fluid_synth_polymono.c, fluid_synth_mono.c) that must be
added to the make steps.
May be Pedro Lopez-Cabanillas can help on this matter ?