The Plugin Pin dialog still shows all options, which can
potentially be a very large dropdown. During initial setup
however, we only need the common "stereo" and "all", options.
A VST3 plugin can have additional busses which were not
available in older versions of Ardour. For compatibility
reasons those should remain unconnected. This is achieved
by using a custom I/O config (same way a user would configure
this).
This unconditionally enable all busses with connected pins.
It does not provide re/configurable I/O (like Audio Unit), nor
implement dynamic Vst::kIoChanged callbacks. But regardless
this allows for plugins with multiple I/O busses (e.g. drum synths).
When not using inplace processing (because I/O pins connections
are not an identity matrix), dedicated inplace-buffers are used.
Those buffers contain silence on unused ports, and hence always
valid to use. However it is still useful for plugins to know
if a plugin-port is actually used. VST3 can disable busses
for unconnected pins.
This resolves an ambiguity between abs(int) and std::abs(T) which
depends on context and compiler version and optimization.
In context of #9057, (gcc-6.3 -O3) math.h `abs(int)` was used. This
truncated the superclock value to 31 bit in ControlList::extend_to.
The previous code only used the 1st multiplicand was use to
determine the direction of rounding, breaking commutative property
`muldiv_round (1, 3, 4) != muldiv_round (3, 1, 4)`
This concept from 2007 is no longer required Temporal::get_grid
already limits the number of grid-lines depending on the step
size (mod-bar, beat_div) and start/end positions.
Previously the current iterator bbt was moved to p->bbt().
From then on, no grid line is reached if the point p is not on
a bar and mod_bar != 0 or the point is not on an expected beat_div.
e.g. when using bbt += mod_bar, and a tempo-change is at 5|2|0.
iterations continues 6|2|0 7|2|0 is_bar() is always false
and no more grid-lines were added.
Rather than trying
bbt = round-up-to-next-grid-mod-div
and then finding the metric for that position, this
approach only does the latter using the already incremented
BBT position.
