Disambiguate export formats with different encoder
qualities, sample-formats or settings (wav/bwav).
This allows to export multipe mp3 with different bitrates.
When multiple child processes are running, closing the
stdin of one child did not send EOF or cause POLLNVAL,
as long as a dup()'ed filedes still existed.
This fixes an issue when running an mp3 encoder while the
video monitor is visible, and will allow to concurrently
run multiple mp3 encoders or other child processes.
Previously this caused Ardour to hang indefinitely in CmdPipeWriter
```
_proc->close_stdin();
_proc->wait(); // << here
```
This is mostly a simple lexical search+replace but the absence of operator< for
std::weak_ptr<T> leads to some complications, particularly with Evoral::Sequence
and ExportPortChannel.
This fixes an issue when changing port-configuration
or toggle strict-i/o of latent multi-out plugins.
`Session::auto_connect_thread_run` can run concurrently
while ports are added/removed from the GUI thread.
The latter invalidates IO::_port PortSet, while
the former thread iterates over ports.
This also changes the IO-Mutex into a RWLock to allow
concurrent access when possible.
Due to rounding (r->position_sample() - start.samples())
can become negative even if (r->position () >= start).
with k = start_division and start_division < 0 this
caused an invalid vector access `layers[j-1][k]`.
This fixes a crash in some plugins (e.g. Auburn Sounds Couture)
when disconnecting all inputs (e.g. moved before a synth).
Previously run was called with numChannels = 0
Even though the plugin refused to be configured that way.
This enables all channels left of the last connected pin
for each given bus. e.g. when using just the 2nd (right)
input of a given bus, the plugin is configure in stereo
mode, with the 1st (left) input being fed with silence.
VST3 does not have a "right-channel mono" configuration.
It is also preferable to have Ardour do the pin/channel
mapping.
This fixes an issue with recent JUCE when using a stereo
plugin on a mono track.
`juce::validateLayouts` requires that numChnanels matches
the configured channel-mapping:
69795dc8e5/modules/juce_audio_processors/format_types/juce_VST3Common.h (L630)
JUCE could be more liberal and accept
`(int) mapIterator->size() > it->numChannels`
