Engine: Silence outputs for 1/2 second when loading a session

This allows for caches to warm up, background worker threads to
spin up and things settle down. This also prevents initial
audible artifacts of live input.

In almost all cases this completes before the GUI is brought up.

1 files changed, 5 insertions, 2 deletions

diff --git a/libs/ardour/audioengine.cc b/libs/ardour/audioengine.cc
index b82b9628f8..c525c33fd4 100644
--- a/libs/ardour/audioengine.cc
+++ b/libs/ardour/audioengine.cc
@@ -288,9 +288,12 @@ AudioEngine::process_callback (pframes_t nframes)
 		--_init_countdown;
 		/* Warm up caches */
 		PortManager::cycle_start (nframes);
-		PortManager::silence (nframes);
 		_session->process (nframes);
+		PortManager::silence (nframes);
 		PortManager::cycle_end (nframes);
+		if (_init_countdown == 0) {
+			_session->reset_xrun_count();
+		}
 		return 0;
 	}
 
@@ -723,7 +726,7 @@ AudioEngine::set_session (Session *s)
 	SessionHandlePtr::set_session (s);
 
 	if (_session) {
-		_init_countdown = 8;
+		_init_countdown = std::max (8, (int)(_backend->sample_rate () / _backend->buffer_size ()) / 2);
 	}
 }