add some utility functions to Buffers and BufferSets to allow some kinds of debugging easily

libs/ardour/ardour/audio_buffer.h

@@ -42,6 +42,8 @@ public:
 	 */
 	void silence (samplecnt_t len, samplecnt_t offset = 0);
 
+	bool silent_data() const;
+
 	/** Copy samples from src array starting at src_offset into self starting at dst_offset
 	 * @param src array to read from
 	 * @param len number of samples to copy

libs/ardour/ardour/buffer.h

@@ -69,6 +69,9 @@ public:
 	/** Clear (eg zero, or empty) buffer */
 	virtual void silence (samplecnt_t len, samplecnt_t offset = 0) = 0;
 
+	/* return true if all data is silent (or for MIDI-like, non-existent */
+	virtual bool silent_data () const = 0;
+
 	/** Clear the entire buffer */
 	virtual void clear() { silence(_capacity, 0); }
 

libs/ardour/ardour/buffer_set.h

@@ -82,6 +82,9 @@ public:
 	void ensure_buffers(DataType type, size_t num_buffers, size_t buffer_capacity);
 	void ensure_buffers(const ChanCount& chns, size_t buffer_capacity);
 
+	/* Returns true if Buffer::silent_data() is true for all buffers */
+	bool silent_data() const;
+
 	const ChanCount& available() const { return _available; }
 	ChanCount&       available()       { return _available; }
 

libs/ardour/ardour/midi_buffer.h

@@ -59,6 +59,7 @@ public:
 	void resize(size_t);
 	size_t size() const { return _size; }
 	bool empty() const { return _size == 0; }
+	bool silent_data () const { return _size == 0; }
 
 	bool insert_event(const Evoral::Event<TimeType>& event);
 	bool merge_in_place(const MidiBuffer &other);

libs/ardour/audio_buffer.cc

@@ -81,6 +81,17 @@ AudioBuffer::check_silence (pframes_t nframes, pframes_t& n) const
 	return true;
 }
 
+bool
+AudioBuffer::silent_data () const
+{
+	for (pframes_t n = 0; n < _capacity; ++n) {
+		if (_data[n]) {
+			return false;
+		}
+	}
+	return true;
+}
+
 void
 AudioBuffer::silence (samplecnt_t len, samplecnt_t offset) {
 

libs/ardour/buffer_set.cc

@@ -229,6 +229,19 @@ BufferSet::ensure_buffers(const ChanCount& chns, size_t buffer_capacity)
 	}
 }
 
+bool
+BufferSet::silent_data () const
+{
+	for (DataType::iterator t = DataType::begin(); t != DataType::end(); ++t) {
+		for (BufferSet::const_iterator i = begin (*t); i != end (*t); ++i) {
+			if (!i->silent_data ()) {
+				return false;
+			}
+		}
+	}
+	return true;
+}
+
 /** Get the capacity (size) of the available buffers of the given type.
  *
  * All buffers of a certain type always have the same capacity.