4 files changed, 14 insertions, 9 deletions

diff --git a/libs/ardour/ardour/buffer_manager.h b/libs/ardour/ardour/buffer_manager.h
index f5a3935ead..c73b59b763 100644
--- a/libs/ardour/ardour/buffer_manager.h
+++ b/libs/ardour/ardour/buffer_manager.h
@@ -40,7 +40,7 @@ public:
 	static ThreadBuffers* get_thread_buffers ();
 	static void           put_thread_buffers (ThreadBuffers*);
 
-	static void ensure_buffers (ChanCount howmany = ChanCount::ZERO);
+	static void ensure_buffers (ChanCount howmany = ChanCount::ZERO, size_t custom = 0);
 
 private:
         static Glib::Threads::Mutex rb_mutex;
diff --git a/libs/ardour/ardour/thread_buffers.h b/libs/ardour/ardour/thread_buffers.h
index f30476a474..bf686fd57e 100644
--- a/libs/ardour/ardour/thread_buffers.h
+++ b/libs/ardour/ardour/thread_buffers.h
@@ -35,7 +35,7 @@ public:
 	ThreadBuffers ();
 	~ThreadBuffers ();
 
-	void ensure_buffers (ChanCount howmany = ChanCount::ZERO);
+	void ensure_buffers (ChanCount howmany = ChanCount::ZERO, size_t custom = 0);
 
 	BufferSet* silent_buffers;
 	BufferSet* scratch_buffers;
diff --git a/libs/ardour/buffer_manager.cc b/libs/ardour/buffer_manager.cc
index c8819e41cb..c221837af8 100644
--- a/libs/ardour/buffer_manager.cc
+++ b/libs/ardour/buffer_manager.cc
@@ -75,11 +75,11 @@ BufferManager::put_thread_buffers (ThreadBuffers* tbp)
 }
 
 void
-BufferManager::ensure_buffers (ChanCount howmany)
+BufferManager::ensure_buffers (ChanCount howmany, size_t custom)
 {
         /* this is protected by the audioengine's process lock: we do not  */
 
 	for (ThreadBufferList::iterator i = thread_buffers_list->begin(); i != thread_buffers_list->end(); ++i) {
-		(*i)->ensure_buffers (howmany);
+		(*i)->ensure_buffers (howmany, custom);
 	}
 }
diff --git a/libs/ardour/thread_buffers.cc b/libs/ardour/thread_buffers.cc
index 94490ca912..b51576bfc9 100644
--- a/libs/ardour/thread_buffers.cc
+++ b/libs/ardour/thread_buffers.cc
@@ -40,7 +40,7 @@ ThreadBuffers::ThreadBuffers ()
 }
 
 void
-ThreadBuffers::ensure_buffers (ChanCount howmany)
+ThreadBuffers::ensure_buffers (ChanCount howmany, size_t custom)
 {
 	// std::cerr << "ThreadBuffers " << this << " resize buffers with count = " << howmany << std::endl;
 
@@ -60,9 +60,14 @@ ThreadBuffers::ensure_buffers (ChanCount howmany)
 
 	for (DataType::iterator t = DataType::begin(); t != DataType::end(); ++t) {
 		size_t count = std::max (scratch_buffers->available().get(*t), howmany.get(*t));
-		size_t size = (*t == DataType::MIDI)
-			? _engine->raw_buffer_size (*t)
-			: _engine->raw_buffer_size (*t) / sizeof (Sample);
+		size_t size;
+		if (custom > 0) {
+			size = custom;
+		} else {
+			size = (*t == DataType::MIDI)
+				? _engine->raw_buffer_size (*t)
+				: _engine->raw_buffer_size (*t) / sizeof (Sample);
+		}
 
 		scratch_buffers->ensure_buffers (*t, count, size);
 		mix_buffers->ensure_buffers (*t, count, size);
@@ -70,7 +75,7 @@ ThreadBuffers::ensure_buffers (ChanCount howmany)
 		route_buffers->ensure_buffers (*t, count, size);
 	}
 
-	size_t audio_buffer_size = _engine->raw_buffer_size (DataType::AUDIO) / sizeof (Sample);
+	size_t audio_buffer_size = custom > 0 ? custom : _engine->raw_buffer_size (DataType::AUDIO) / sizeof (Sample);
 
 	delete [] gain_automation_buffer;
 	gain_automation_buffer = new gain_t[audio_buffer_size];