* forward midi-data around plugins that have no MIDI-out
* allow to insert plugins with no MIDI-input at a point with one MIDI-channel
This works because excess ports (both plugin and route) remain
unconnected and use scratch-buffers.
Tested with LV2, LXVST and LADSPA.
(AU plugins with variable in/out retain the old behavior, no bypass)
fixes http://tracker.ardour.org/view.php?id=5630
Plugins rewrite the buffer data in-place and some plugins
can produce output even when fed with silence.
Hence, during a PluginInsert::silence() run a plugin can
inject data into the "silent" buffers which causes side-effects.
Kudos to Chris 'oofus' Goddard for finding this issue.
"scratch buffers are by definition scratch and their contents are undefined at all times"
"silent buffers are by definition all-zero and should not be used for real data"
But track & route were using those for actual data; plugins (which may run
in the same thread and may get the same buffers) use them for scratch thereby
overwriting real data.
In particular get_silent_buffers() (used by LadspaPlugin::connect_and_run)
clears the buffer which can holds real data:
e.g. via Route::passthru_silence() -> plugin1 -> plugin2 (clears output of plugin1)
- replaces fix in 066df0d218
- Check if _LIBCPP_VECTOR is defined for vector_delete.
This is defined in libc++'s headers which Apple is using
instead of libstdc++
before this change:
1) switch to 'custom' meter point,
2) deactivate meter processor.
-> meters does not run regardless of meter-point
-> meter can only be re-nabled in 'custom' mode
..and continue to calculate fall-off in
audio-cycle (rather than UI thread)
TODO: check if this works properly when switching
between audio/midi meter modes on a midi-track.
One of the motivations to always reset meters when the
meter-point changes was to resolve peak-hold & fall-off
issues when a midi-meter replaces an audio-meter and vice
versa.
