Add a fixed (not de-clicked) multi-buffer audio/midi delayline.

A ringbuffer intended to be used for plugin-thru/bypass
latency compensation.

libs/ardour/ardour/fixed_delay.h

@@ -0,0 +1,67 @@
+/*
+ * Copyright (C) 2016 Robin Gareus <robin@gareus.org>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+
+#ifndef __ardour_fixed_delay_h__
+#define __ardour_fixed_delay_h__
+
+#include <vector>
+#include "ardour/buffer.h"
+
+namespace ARDOUR {
+
+class ChanCount;
+
+class LIBARDOUR_API FixedDelay
+{
+public:
+	FixedDelay ();
+	~FixedDelay ();
+
+	void configure (const ChanCount& count, framecnt_t);
+	void set (const ChanCount& count, framecnt_t);
+
+	void delay (ARDOUR::DataType, uint32_t, Buffer&, const Buffer&, pframes_t, framecnt_t dst_offset = 0, framecnt_t src_offset = 0);
+	void flush() { _pending_flush = true; }
+
+private:
+	framecnt_t _max_delay;
+	framecnt_t _delay;
+	bool       _pending_flush;
+	ChanCount  _count;
+
+	struct DelayBuffer {
+		public:
+		DelayBuffer () : buf (0), pos (0) {}
+		DelayBuffer (DataType dt, size_t capacity)
+			: buf (Buffer::create (dt, capacity)), pos (0) {}
+		~DelayBuffer () { delete buf; }
+		Buffer * buf;
+		framepos_t pos;
+	};
+
+	typedef std::vector<DelayBuffer*> BufferVec;
+	// Vector of vectors, indexed by DataType
+	std::vector<BufferVec> _buffers;
+
+	void ensure_buffers(DataType type, size_t num_buffers, size_t buffer_capacity);
+	void clear ();
+};
+
+} // namespace ARDOUR
+
+#endif // __ardour_fixed_delay_h__

libs/ardour/fixed_delay.cc

@@ -0,0 +1,132 @@
+/*
+ * Copyright (C) 2016 Robin Gareus <robin@gareus.org>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+
+#include "ardour/audio_buffer.h"
+#include "ardour/buffer_set.h"
+#include "ardour/fixed_delay.h"
+#include "ardour/midi_buffer.h"
+
+using namespace ARDOUR;
+
+FixedDelay::FixedDelay ()
+	: _max_delay (0)
+	, _delay (0)
+	, _pending_flush (false)
+{
+	for (size_t i = 0; i < DataType::num_types; ++i) {
+		_buffers.push_back (BufferVec ());
+	}
+	_count.reset ();
+}
+
+FixedDelay::~FixedDelay ()
+{
+	clear ();
+}
+
+void
+FixedDelay::configure (const ChanCount& count, framecnt_t max_delay)
+{
+	if (max_delay <= _max_delay || count <= _count) {
+		return;
+	}
+	_max_delay = std::max (_max_delay, max_delay);
+	for (DataType::iterator i = DataType::begin (); i != DataType::end (); ++i) {
+		ensure_buffers (*i, count.get (*i), _max_delay + 1);
+	}
+}
+
+void
+FixedDelay::set (const ChanCount& count, framecnt_t delay)
+{
+	configure (count, delay);
+	_delay = delay;
+}
+
+void
+FixedDelay::ensure_buffers (DataType type, size_t num_buffers, size_t buffer_capacity)
+{
+	assert (type != DataType::NIL);
+	assert (type < _buffers.size ());
+	if (num_buffers == 0) {
+		return;
+	}
+	BufferVec& bufs = _buffers[type];
+	if (bufs.size () < num_buffers || (bufs.size () > 0 && bufs[0]->buf->capacity () < buffer_capacity)) {
+		for (BufferVec::iterator i = bufs.begin (); i != bufs.end (); ++i) {
+			delete (*i);
+		}
+		bufs.clear ();
+		for (size_t i = 0; i < num_buffers; ++i) {
+			bufs.push_back (new DelayBuffer (type, buffer_capacity));
+		}
+		_count.set (type, num_buffers);
+	}
+}
+
+void
+FixedDelay::clear ()
+{
+	for (std::vector<BufferVec>::iterator i = _buffers.begin (); i != _buffers.end (); ++i) {
+		for (BufferVec::iterator j = (*i).begin (); j != (*i).end (); ++j) {
+			delete *j;
+		}
+		(*i).clear ();
+	}
+	_buffers.clear ();
+	_count.reset ();
+}
+
+void
+FixedDelay::delay (
+		ARDOUR::DataType dt, uint32_t id,
+		Buffer& out, const Buffer& in,
+		pframes_t n_frames,
+		framecnt_t dst_offset, framecnt_t src_offset)
+{
+	if (_delay == 0) {
+		out.read_from (in, n_frames, dst_offset, src_offset);
+		return;
+	}
+
+	assert (dt < _buffers.size ());
+	assert (id < _buffers[dt].size ());
+	DelayBuffer *db = _buffers[dt][id];
+
+	if (db->pos + n_frames > _max_delay) {
+		uint32_t w0 = _max_delay - db->pos;
+		uint32_t w1 = db->pos + n_frames - _max_delay;
+		db->buf->read_from (in, w0, db->pos, src_offset);
+		db->buf->read_from (in, w1, 0, src_offset + w0);
+	} else {
+		db->buf->read_from (in, n_frames, db->pos, src_offset);
+	}
+
+	uint32_t rp = (db->pos + _max_delay - _delay) % _max_delay;
+
+	if (rp + n_frames > _max_delay) {
+		uint32_t r0 = _max_delay - rp;
+		uint32_t r1 = rp + n_frames - _max_delay;
+		out.read_from (*db->buf, r0, dst_offset, rp);
+		out.read_from (*db->buf, r1, dst_offset + r0, 0);
+	} else {
+		out.read_from (*db->buf, n_frames, dst_offset, rp);
+	}
+
+	db->pos = (db->pos + n_frames) % _max_delay;
+}

libs/ardour/wscript

@@ -92,6 +92,7 @@ libardour_sources = [
         'filesystem_paths.cc',
         'filter.cc',
         'find_session.cc',
+        'fixed_delay.cc',
         'gain_control.cc',
         'globals.cc',
         'graph.cc',