Users should be able to see the playlist they're about to switch to
while the dialog is up. Additionally, if the user cancels, the change
should be nullified and the original playlist used.
Fixes issue where the export dmeo noise level was not being applied
correctly because ExportFormatDialog::update_demo_noise_selection was
not being called
This can happen during pre-roll when buffers are filled
to start audible playback at zero.
While the position argument is signed for all plugin-standards,
it seems that some do not support negative timestamps before
00:00:00:00. (e.g. https://github.com/falkTX/Carla/issues/1236)
Furthermore TempoMap::bbt_at_sample() returns 0 for all negative
timestamps, but it was possible tthat tempo-map transmission,
as well as beat-position returned negative values.
When the engine is restarted, ports are re-established,
and previously queued port-connections need to be cleared.
This caused a bug:
* when the engine is stopped all ports are disconnected.
_port_connection_queue contains all disconnections
* engine is stopped so _port_connection_queue is not processed
* engine-restart re-etablishes ports and appends those connections
to _port_connection_queue
* process-callback processes the list in **reverse** order
```
while (!_port_connection_queue.empty ()) {
_port_connection_queue.pop_back ();
}
```
* ARDOUR::PortManager::connect_callback() is first called
with connected() and the disconnected()
* All ports are assumed to not be connected
Port::_externally_connected == 0 for all ports
Result:
* vari-speed playback resampling does not work (only external
I/O is reampled), split cycles processing (looping) fails
since AudioPort::get_audio_buffer() does not apply the
_global_port_buffer_offset
