tentative fix for a crash that occurs when switching backends.5.0-pre1

Session::process() returns early with Session::_silent set to true. AudioBuffer::set_data()
was never set for (at least) the LTC output port. PortManager::cycle_end() calls
AudioBuffer::silence() which used to assume that get_buffer() must have been called. But it
was not, because that should have happened in Session::process().

So check AudioBuffer::data() and call get_buffer() if required.

1 files changed, 5 insertions, 2 deletions

diff --git a/libs/ardour/audio_port.cc b/libs/ardour/audio_port.cc
index e2bb20dbe9..33e41c10ad 100644
--- a/libs/ardour/audio_port.cc
+++ b/libs/ardour/audio_port.cc
@@ -59,8 +59,11 @@ void
 AudioPort::cycle_end (pframes_t nframes)
 {
         if (sends_output() && !_buffer->written()) {
-		if (_buffer->capacity() >= nframes) {
-			_buffer->silence (nframes);
+	        if (!_buffer->data (0)) {
+		        get_audio_buffer (nframes);
+	        }
+	        if (_buffer->capacity() >= nframes) {
+		        _buffer->silence (nframes);
 		}
 	}
 }