This picks up where cfd95340b1 left off.
The goal is to ensure that the butler has completed all
PostTransportStop related tasks and won't meddle with transport
after exporting has started.
Previously this could happen, because realtime_stop() queues
PostTransportStop and the butler is sommoned after every
export process cycle.
Since 61e7f3176b the butler keeps calling non_realtime_stop()
every time it is woken up, until TFSM comes around and unsets the
flag in the process callback.
Engine backends are loaded dynamically, and Ardour can start without
them. This is manly to relax the requirement of having libpulse.so.
libardour itself depends on libasound, so the ALSA backend is always
present, and the jack-backend dynamically dlopen()s libjack.
This cuts reverb tails and synth sounds after export.
Disabling freewheeling, continues normal processing where
export left off. This previously kept notes ringing, or reverbs
audible.
The actual issue was introduced in 61e7f3176b:
Session::non_realtime_stop() no longer unsets PostTransportStop
(other changes from that commit are not relevant).
The real issue however is a race-condition.
So far this only seems to happen on MacOS, Coreaudio.
It seems that non_realtime_stop() is called in the butler-thread
after exporting has started, even though the butler has been
paused in wait_until_finished().
Perhaps Coreaudio thread switches causes TransportFSM to
reinitialize and scheduling the butler?
The use of `usleep()` makes this rather a workaround.
However it's sufficient for the coreaudio rt thread to run
at least once.
Port (or Tracks) can be safely added during playback, however
the disk-reader's playback buffer is initially empty. This lead to
false-positive Underrun() signals when processing takes place
before or concurrently with re-filling the disk-buffer for the new
channels.
Now new empty buffers are ignored, and produce silence until the
initial refill is complete. There is however no per-channel
de-click in, yet.
This fixes: play some audio track, ctrl+drag a region to the
drop-zone, creating a new track while playing.
Main features: Plugin (Select & Edit)
1. Plugin Select: When a track is selected that has PluginInserts, pushing the "Plug-In" button on a mackie will list these across the strips. Clicking a vpot of a strip enables editing the parameters of this selected plugin.
2. Plugin Edit: When a Plugin is selected for editing, the input parameters of the plugin are shown across the channel strips and the vpot is assigned the corresponsing AutomationControl for the parameter.
Minor features
- When the number of plugins or the number of parameters exceeds the number of strips available on the surface, one can flip through "pages" of views using the Cursor Left and Right keys (this logic I took from http://www.emagic.de/media/support/content/manuals/LogicControl_en.pdf)
- When in the Plugin Select mode, rearranging the plugins in the mixer strip is reflected on the surface.
- When in Plugin Edit mode, rearranging the plugins in the mixer strip still retains the edit view of the selected plugin (rearranging does not take away the current subview)
- When removing a plugin in the mixer strip, this is reflected in Plugin Select, while the view jumps to Pan/Surround (the None subview) when in Plugin Edit mode.
- Removing a track resets the subview to None
- When in a Subview that is track-specific (Track, EQ, Send, Plug-In, Inst), selecting a different track retains the subview but updates the channel displays and vpot assignments accordingly. When in Plugin Edit mode for track A, and track B is selected, it changes to Plugin Select mode for track B (if plugins are present).
