rollback to 3428, before the mysterious removal of libs/* at 3431/3432

git-svn-id: svn://localhost/ardour2/branches/3.0@3435 d708f5d6-7413-0410-9779-e7cbd77b26cf

1 files changed, 904 insertions, 0 deletions

diff --git a/libs/ardour/crossfade.cc b/libs/ardour/crossfade.cc
new file mode 100644
index 0000000000..f3dfa28165
--- /dev/null
+++ b/libs/ardour/crossfade.cc
@@ -0,0 +1,904 @@
+/*
+    Copyright (C) 2003-2006 Paul Davis 
+
+    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., 675 Mass Ave, Cambridge, MA 02139, USA.
+
+*/
+
+#include <sigc++/bind.h>
+
+#include <pbd/stacktrace.h>
+
+#include <ardour/types.h>
+#include <ardour/crossfade.h>
+#include <ardour/crossfade_compare.h>
+#include <ardour/audioregion.h>
+#include <ardour/playlist.h>
+#include <ardour/utils.h>
+#include <ardour/session.h>
+#include <ardour/source.h>
+
+#include "i18n.h"
+#include <locale.h>
+
+using namespace std;
+using namespace ARDOUR;
+using namespace PBD;
+
+nframes_t Crossfade::_short_xfade_length = 0;
+Change Crossfade::ActiveChanged = new_change();
+Change Crossfade::FollowOverlapChanged = new_change();
+
+/* XXX if and when we ever implement parallel processing of the process()
+   callback, these will need to be handled on a per-thread basis.
+*/
+
+Sample* Crossfade::crossfade_buffer_out = 0;
+Sample* Crossfade::crossfade_buffer_in = 0;
+
+void
+Crossfade::set_buffer_size (nframes_t sz)
+{
+	if (crossfade_buffer_out) {
+		delete [] crossfade_buffer_out;
+		crossfade_buffer_out = 0;
+	}
+
+	if (crossfade_buffer_in) {
+		delete [] crossfade_buffer_in;
+		crossfade_buffer_in = 0;
+	}
+
+	if (sz) {
+		crossfade_buffer_out = new Sample[sz];
+		crossfade_buffer_in = new Sample[sz];
+	}
+}
+
+bool
+Crossfade::operator== (const Crossfade& other)
+{
+	return (_in == other._in) && (_out == other._out);
+}
+
+Crossfade::Crossfade (boost::shared_ptr<AudioRegion> in, boost::shared_ptr<AudioRegion> out, 
+		      nframes_t length,
+		      nframes_t position,
+		      AnchorPoint ap)
+	: AudioRegion (in->session(), position, length, "foobar"),
+	  _fade_in (Parameter(FadeInAutomation), 0.0, 2.0, 1.0), // linear (gain coefficient) => -inf..+6dB
+	  _fade_out (Parameter(FadeOutAutomation), 0.0, 2.0, 1.0) // linear (gain coefficient) => -inf..+6dB
+
+{
+	_in = in;
+	_out = out;
+
+	_anchor_point = ap;
+	_follow_overlap = false;
+
+	_active = Config->get_xfades_active ();
+	_fixed = true;
+
+	initialize ();
+}
+
+Crossfade::Crossfade (boost::shared_ptr<AudioRegion> a, boost::shared_ptr<AudioRegion> b, CrossfadeModel model, bool act)
+	: AudioRegion (a->session(), 0, 0, "foobar"),
+	  _fade_in (Parameter(FadeInAutomation), 0.0, 2.0, 1.0), // linear (gain coefficient) => -inf..+6dB
+	  _fade_out (Parameter(FadeOutAutomation), 0.0, 2.0, 1.0) // linear (gain coefficient) => -inf..+6dB
+{
+	_in_update = false;
+	_fixed = false;
+
+	if (compute (a, b, model)) {
+		throw failed_constructor();
+	}
+
+	_active = act;
+
+	initialize ();
+
+
+}
+
+Crossfade::Crossfade (const Playlist& playlist, XMLNode& node)
+	: AudioRegion (playlist.session(), 0, 0, "foobar"),
+	  _fade_in (Parameter(FadeInAutomation), 0.0, 2.0, 1.0), // linear (gain coefficient) => -inf..+6dB
+	  _fade_out (Parameter(FadeOutAutomation), 0.0, 2.0, 1.0) // linear (gain coefficient) => -inf..+6dB
+
+{
+	boost::shared_ptr<Region> r;
+	XMLProperty* prop;
+	LocaleGuard lg (X_("POSIX"));
+
+	/* we have to find the in/out regions before we can do anything else */
+
+	if ((prop = node.property ("in")) == 0) {
+		error << _("Crossfade: no \"in\" region in state") << endmsg;
+		throw failed_constructor();
+	}
+	
+	PBD::ID id (prop->value());
+
+	if ((r = playlist.find_region (id)) == 0) {
+		error << string_compose (_("Crossfade: no \"in\" region %1 found in playlist %2"), id, playlist.name())
+		      << endmsg;
+		throw failed_constructor();
+	}
+	
+	if ((_in = boost::dynamic_pointer_cast<AudioRegion> (r)) == 0) {
+		throw failed_constructor();
+	}
+
+	if ((prop = node.property ("out")) == 0) {
+		error << _("Crossfade: no \"out\" region in state") << endmsg;
+		throw failed_constructor();
+	}
+
+	PBD::ID id2 (prop->value());
+
+	if ((r = playlist.find_region (id2)) == 0) {
+		error << string_compose (_("Crossfade: no \"out\" region %1 found in playlist %2"), id2, playlist.name())
+		      << endmsg;
+		throw failed_constructor();
+	}
+	
+	if ((_out = boost::dynamic_pointer_cast<AudioRegion> (r)) == 0) {
+		throw failed_constructor();
+	}
+
+	_length = 0;
+	initialize();
+	_active = true;
+	
+	if (set_state (node)) {
+		throw failed_constructor();
+	}
+}
+
+Crossfade::Crossfade (boost::shared_ptr<Crossfade> orig, boost::shared_ptr<AudioRegion> newin, boost::shared_ptr<AudioRegion> newout)
+	: AudioRegion (boost::dynamic_pointer_cast<const AudioRegion> (orig)),
+	  _fade_in (orig->_fade_in),
+	  _fade_out (orig->_fade_out)
+{
+	_active           = orig->_active;
+	_in_update        = orig->_in_update;
+	_anchor_point     = orig->_anchor_point;
+	_follow_overlap   = orig->_follow_overlap;
+	_fixed            = orig->_fixed;
+	
+	_in = newin;
+	_out = newout;
+
+	// copied from Crossfade::initialize()
+	_in_update = false;
+	
+	_out->suspend_fade_out ();
+	_in->suspend_fade_in ();
+
+	overlap_type = _in->coverage (_out->position(), _out->last_frame());
+	layer_relation = (int32_t) (_in->layer() - _out->layer());
+
+	// Let's make sure the fade isn't too long
+	set_length(_length);
+}
+
+
+Crossfade::~Crossfade ()
+{
+	notify_callbacks ();
+}
+
+void
+Crossfade::initialize ()
+{
+	/* merge source lists from regions */
+
+	_sources = _in->sources();
+	_sources.insert (_sources.end(), _out->sources().begin(), _out->sources().end());
+	_master_sources = _in->master_sources();
+	_master_sources.insert(_master_sources.end(), _out->master_sources().begin(), _out->master_sources().end());
+	
+	_in_update = false;
+	
+	_out->suspend_fade_out ();
+	_in->suspend_fade_in ();
+
+	_fade_out.freeze ();
+	_fade_out.clear ();
+	_fade_out.add (0.0, 1.0);
+	_fade_out.add ((_length * 0.1), 0.99);
+	_fade_out.add ((_length * 0.2), 0.97);
+	_fade_out.add ((_length * 0.8), 0.03);
+	_fade_out.add ((_length * 0.9), 0.01);
+	_fade_out.add (_length, 0.0);
+	_fade_out.thaw ();
+	
+	_fade_in.freeze ();
+	_fade_in.clear ();
+	_fade_in.add (0.0, 0.0);
+	_fade_in.add ((_length * 0.1),  0.01);
+	_fade_in.add ((_length * 0.2),  0.03);
+	_fade_in.add ((_length * 0.8),  0.97);
+	_fade_in.add ((_length * 0.9),  0.99);
+	_fade_in.add (_length, 1.0);
+	_fade_in.thaw ();
+
+	overlap_type = _in->coverage (_out->position(), _out->last_frame());
+	layer_relation = (int32_t) (_in->layer() - _out->layer());
+}	
+
+nframes_t 
+Crossfade::read_raw_internal (Sample* buf, nframes_t start, nframes_t cnt) const
+{
+#if 0
+	Sample* mixdown = new Sample[cnt];
+	float* gain = new float[cnt];
+	nframes_t ret;
+
+	ret = read_at (buf, mixdown, gain, start, cnt, chan_n, cnt);
+
+	delete [] mixdown;
+	delete [] gain;
+
+	return ret;
+#endif
+	return cnt;
+}
+
+nframes_t 
+Crossfade::read_at (Sample *buf, Sample *mixdown_buffer, 
+		    float *gain_buffer, nframes_t start, nframes_t cnt, uint32_t chan_n,
+		    nframes_t read_frames, nframes_t skip_frames) const
+{
+	nframes_t offset;
+	nframes_t to_write;
+
+	if (!_active) {
+		return 0;
+	}
+
+	if (start < _position) {
+
+		/* handle an initial section of the read area that we do not
+		   cover.
+		*/
+
+		offset = _position - start;
+
+		if (offset < cnt) {
+			cnt -= offset;
+		} else {
+			return 0;
+		}
+		
+		start = _position;
+		buf += offset;
+		to_write = min (_length, cnt);
+
+	} else {
+		
+		to_write = min (_length - (start - _position), cnt);
+		
+	}
+
+	offset = start - _position;
+
+	/* Prevent data from piling up inthe crossfade buffers when reading a transparent region */
+	if (!(_out->opaque())) {
+		memset (crossfade_buffer_out, 0, sizeof (Sample) * to_write);
+	} else if (!(_in->opaque())) {
+		memset (crossfade_buffer_in, 0, sizeof (Sample) * to_write);
+	}
+
+	_out->read_at (crossfade_buffer_out, mixdown_buffer, gain_buffer, start, to_write, chan_n, read_frames, skip_frames);
+	_in->read_at (crossfade_buffer_in, mixdown_buffer, gain_buffer, start, to_write, chan_n, read_frames, skip_frames);
+
+	float* fiv = new float[to_write];
+	float* fov = new float[to_write];
+
+	_fade_in.curve().get_vector (offset, offset+to_write, fiv, to_write);
+	_fade_out.curve().get_vector (offset, offset+to_write, fov, to_write);
+
+	/* note: although we have not explicitly taken into account the return values
+	   from _out->read_at() or _in->read_at(), the length() function does this
+	   implicitly. why? because it computes a value based on the in+out regions'
+	   position and length, and so we know precisely how much data they could return. 
+	*/
+
+	for (nframes_t n = 0; n < to_write; ++n) {
+		buf[n] = (crossfade_buffer_out[n] * fov[n]) + (crossfade_buffer_in[n] * fiv[n]);
+	}
+
+	delete [] fov;
+	delete [] fiv;
+
+	return to_write;
+}	
+
+OverlapType 
+Crossfade::coverage (nframes_t start, nframes_t end) const
+{
+	nframes_t my_end = _position + _length;
+
+	if ((start >= _position) && (end <= my_end)) {
+		return OverlapInternal;
+	}
+	if ((end >= _position) && (end <= my_end)) {
+		return OverlapStart;
+	}
+	if ((start >= _position) && (start <= my_end)) {
+		return OverlapEnd;
+	}
+	if ((_position >= start) && (_position <= end) && (my_end <= end)) {
+		return OverlapExternal;
+	}
+	return OverlapNone;
+}
+
+void
+Crossfade::set_active (bool yn)
+{
+	if (_active != yn) {
+		_active = yn;
+		StateChanged (ActiveChanged);
+	}
+}
+
+bool
+Crossfade::refresh ()
+{
+	/* crossfades must be between non-muted regions */
+	
+	if (_out->muted() || _in->muted()) {
+		Invalidated (shared_from_this ());
+		return false;
+	}
+
+	/* Top layer shouldn't be transparent */
+	
+	if (!((layer_relation > 0 ? _in : _out)->opaque())) {
+		Invalidated (shared_from_this());
+		return false;
+	}
+
+	/* layer ordering cannot change */
+
+	int32_t new_layer_relation = (int32_t) (_in->layer() - _out->layer());
+
+	if (new_layer_relation * layer_relation < 0) { // different sign, layers rotated 
+		Invalidated (shared_from_this ());
+		return false;
+	}
+
+	OverlapType ot = _in->coverage (_out->first_frame(), _out->last_frame());
+
+	if (ot == OverlapNone) {
+		Invalidated (shared_from_this ());
+		return false;
+	} 
+
+	bool send_signal;
+
+	if (ot != overlap_type) {
+
+		if (_follow_overlap) {
+
+			try {
+				compute (_in, _out, Config->get_xfade_model());
+			} 
+
+			catch (NoCrossfadeHere& err) {
+				Invalidated (shared_from_this ());
+				return false;
+			}
+
+			send_signal = true;
+
+		} else {
+
+			Invalidated (shared_from_this ());
+			return false;
+		}
+
+	} else {
+
+		send_signal = update ();
+	}
+
+	if (send_signal) {
+		StateChanged (BoundsChanged); /* EMIT SIGNAL */
+	}
+
+	_in_update = false;
+
+	return true;
+}
+
+bool
+Crossfade::update ()
+{
+	nframes_t newlen;
+	
+	if (_follow_overlap) {
+		newlen = _out->first_frame() + _out->length() - _in->first_frame();
+	} else {
+		newlen = _length;
+	}
+	
+	if (newlen == 0) {
+		Invalidated (shared_from_this ());
+		return false;
+	}
+	
+	_in_update = true;
+	
+	if ((_follow_overlap && newlen != _length) || (_length > newlen)) {
+		
+		double factor =  newlen / (double) _length;
+		
+		_fade_out.x_scale (factor);
+		_fade_in.x_scale (factor);
+		
+		_length = newlen;
+	} 
+		
+	switch (_anchor_point) {
+	case StartOfIn:
+		_position = _in->first_frame();
+		break;
+		
+	case EndOfIn:
+		_position = _in->last_frame() - _length;
+		break;
+		
+	case EndOfOut:
+		_position = _out->last_frame() - _length;
+	}
+
+	return true;
+}
+
+int
+Crossfade::compute (boost::shared_ptr<AudioRegion> a, boost::shared_ptr<AudioRegion> b, CrossfadeModel model)
+{
+	boost::shared_ptr<AudioRegion> top;
+	boost::shared_ptr<AudioRegion> bottom;
+	nframes_t short_xfade_length;
+
+	short_xfade_length = _short_xfade_length; 
+
+	if (a->layer() < b->layer()) {
+		top = b;
+		bottom = a;
+	} else {
+		top = a;
+		bottom = b;
+	}
+	
+	/* first check for matching ends */
+	
+	if (top->first_frame() == bottom->first_frame()) {
+
+		/* Both regions start at the same point */
+		
+		if (top->last_frame() < bottom->last_frame()) {
+			
+			/* top ends before bottom, so put an xfade
+			   in at the end of top.
+			*/
+			
+			/* [-------- top ---------- ]
+                         * {====== bottom =====================}
+			 */
+
+			_in = bottom;
+			_out = top;
+
+			if (top->last_frame() < short_xfade_length) {
+				_position = 0;
+			} else {
+				_position = top->last_frame() - short_xfade_length;
+			}
+
+			_length = min (short_xfade_length, top->length());
+			_follow_overlap = false;
+			_anchor_point = EndOfIn;
+			_active = true;
+			_fixed = true;
+
+		} else {
+			/* top ends after (or same time) as bottom - no xfade
+			 */
+			
+			/* [-------- top ------------------------ ]
+                         * {====== bottom =====================}
+			 */
+
+			throw NoCrossfadeHere();
+		}
+		
+	} else if (top->last_frame() == bottom->last_frame()) {
+		
+		/* Both regions end at the same point */
+		
+		if (top->first_frame() > bottom->first_frame()) {
+			
+			/* top starts after bottom, put an xfade in at the
+			   start of top
+			*/
+			
+			/*            [-------- top ---------- ]
+                         * {====== bottom =====================}
+			 */
+
+			_in = top;
+			_out = bottom;
+			_position = top->first_frame();
+			_length = min (short_xfade_length, top->length());
+			_follow_overlap = false;
+			_anchor_point = StartOfIn;
+			_active = true;
+			_fixed = true;
+			
+		} else {
+			/* top starts before bottom - no xfade
+			 */
+
+			/* [-------- top ------------------------ ]
+                         *    {====== bottom =====================}
+			 */
+
+			throw NoCrossfadeHere();
+		}
+
+	} else {
+	
+		/* OK, time to do more regular overlapping */
+
+		OverlapType ot = top->coverage (bottom->first_frame(), bottom->last_frame());
+
+		switch (ot) {
+		case OverlapNone:
+			/* should be NOTREACHED as a precondition of creating
+			   a new crossfade, but we need to handle it here.
+			*/
+			throw NoCrossfadeHere();
+			break;
+			
+		case OverlapInternal:
+		case OverlapExternal:
+			/* should be NOTREACHED because of tests above */
+			throw NoCrossfadeHere();
+			break;
+			
+		case OverlapEnd: /* top covers start of bottom but ends within it */
+
+			/* [---- top ------------------------] 
+			 *                { ==== bottom ============ } 
+			 */ 
+
+			_in = bottom;
+			_out = top;
+			_anchor_point = EndOfOut;
+
+			if (model == FullCrossfade) {
+				_position = bottom->first_frame(); // "{"
+				_length = _out->first_frame() + _out->length() - _in->first_frame();
+				/* leave active alone */
+				_follow_overlap = true;
+			} else {
+				_length = min (short_xfade_length, top->length());
+				_position = top->last_frame() - _length;  // "]" - length 
+				_active = true;
+				_follow_overlap = false;
+				
+			}
+			break;
+			
+		case OverlapStart:   /* top starts within bottom but covers bottom's end */
+
+			/*                   { ==== top ============ } 
+			 *   [---- bottom -------------------] 
+			 */
+
+			_in = top;
+			_out = bottom;
+			_position = top->first_frame();
+			_anchor_point = StartOfIn;
+
+			if (model == FullCrossfade) {
+				_length = _out->first_frame() + _out->length() - _in->first_frame();
+				/* leave active alone */
+				_follow_overlap = true;
+			} else {
+				_length = min (short_xfade_length, top->length());
+				_active = true;
+				_follow_overlap = false;
+				
+			}
+			
+			break;
+		}
+	}
+	
+	return 0;
+}
+
+XMLNode&
+Crossfade::get_state () 
+{
+	XMLNode* node = new XMLNode (X_("Crossfade"));
+	XMLNode* child;
+	char buf[64];
+	LocaleGuard lg (X_("POSIX"));
+
+	_out->id().print (buf, sizeof (buf));
+	node->add_property ("out", buf);
+	_in->id().print (buf, sizeof (buf));
+	node->add_property ("in", buf);
+	node->add_property ("active", (_active ? "yes" : "no"));
+	node->add_property ("follow-overlap", (_follow_overlap ? "yes" : "no"));
+	node->add_property ("fixed", (_fixed ? "yes" : "no"));
+	snprintf (buf, sizeof(buf), "%" PRIu32, _length);
+	node->add_property ("length", buf);
+	snprintf (buf, sizeof(buf), "%" PRIu32, (uint32_t) _anchor_point);
+	node->add_property ("anchor-point", buf);
+	snprintf (buf, sizeof(buf), "%" PRIu32, (uint32_t) _position);
+	node->add_property ("position", buf);
+
+	child = node->add_child ("FadeIn");
+
+	for (AutomationList::iterator ii = _fade_in.begin(); ii != _fade_in.end(); ++ii) {
+		XMLNode* pnode;
+
+		pnode = new XMLNode ("point");
+
+		snprintf (buf, sizeof (buf), "%" PRIu32, (nframes_t) floor ((*ii)->when));
+		pnode->add_property ("x", buf);
+		snprintf (buf, sizeof (buf), "%.12g", (*ii)->value);
+		pnode->add_property ("y", buf);
+		child->add_child_nocopy (*pnode);
+	}
+
+	child = node->add_child ("FadeOut");
+
+	for (AutomationList::iterator ii = _fade_out.begin(); ii != _fade_out.end(); ++ii) {
+		XMLNode* pnode;
+
+		pnode = new XMLNode ("point");
+
+		snprintf (buf, sizeof (buf), "%" PRIu32, (nframes_t) floor ((*ii)->when));
+		pnode->add_property ("x", buf);
+		snprintf (buf, sizeof (buf), "%.12g", (*ii)->value);
+		pnode->add_property ("y", buf);
+		child->add_child_nocopy (*pnode);
+	}
+
+	return *node;
+}
+
+int
+Crossfade::set_state (const XMLNode& node)
+{
+	XMLNodeConstIterator i;
+	XMLNodeList children;
+	XMLNode* fi;
+	XMLNode* fo;
+	const XMLProperty* prop;
+	LocaleGuard lg (X_("POSIX"));
+	Change what_changed = Change (0);
+	nframes_t val;
+
+	if ((prop = node.property ("position")) != 0) {
+		sscanf (prop->value().c_str(), "%" PRIu32, &val);
+		if (val != _position) {
+			_position = val;
+			what_changed = Change (what_changed | PositionChanged);
+		}
+	} else {
+		warning << _("old-style crossfade information - no position information") << endmsg;
+		_position = _in->first_frame();
+	}
+
+	if ((prop = node.property ("active")) != 0) {
+		bool x = (prop->value() == "yes");
+		if (x != _active) {
+			_active = x;
+			what_changed = Change (what_changed | ActiveChanged);
+		}
+	} else {
+		_active = true;
+	}
+
+	if ((prop = node.property ("follow-overlap")) != 0) {
+		_follow_overlap = (prop->value() == "yes");
+	} else {
+		_follow_overlap = false;
+	}
+
+	if ((prop = node.property ("fixed")) != 0) {
+		_fixed = (prop->value() == "yes");
+	} else {
+		_fixed = false;
+	}
+
+	if ((prop = node.property ("anchor-point")) != 0) {
+		_anchor_point = AnchorPoint (atoi ((prop->value().c_str())));
+	} else {
+		_anchor_point = StartOfIn;
+	}
+
+	if ((prop = node.property ("length")) != 0) {
+
+		sscanf (prop->value().c_str(), "%" PRIu32, &val);
+		if (val != _length) {
+			_length = atol (prop->value().c_str());
+			what_changed = Change (what_changed | LengthChanged);
+		}
+
+	} else {
+		
+		/* XXX this branch is legacy code from before
+		   the point where we stored xfade lengths.
+		*/
+		
+		if ((_length = overlap_length()) == 0) {
+			throw failed_constructor();
+		}
+	}
+
+	if ((fi = find_named_node (node, "FadeIn")) == 0) {
+		return -1;
+	}
+	
+	if ((fo = find_named_node (node, "FadeOut")) == 0) {
+		return -1;
+	}
+
+	/* fade in */
+	
+	_fade_in.freeze ();
+	_fade_in.clear ();
+	
+	children = fi->children();
+	
+	for (i = children.begin(); i != children.end(); ++i) {
+		if ((*i)->name() == "point") {
+			nframes_t x;
+			float y;
+			
+			prop = (*i)->property ("x");
+			sscanf (prop->value().c_str(), "%" PRIu32, &x);
+			
+			prop = (*i)->property ("y");
+			sscanf (prop->value().c_str(), "%f", &y);
+
+			_fade_in.add (x, y);
+		}
+	}
+
+	_fade_in.thaw ();
+	
+        /* fade out */
+	
+	_fade_out.freeze ();
+	_fade_out.clear ();
+
+	children = fo->children();
+	
+	for (i = children.begin(); i != children.end(); ++i) {
+		if ((*i)->name() == "point") {
+			nframes_t x;
+			float y;
+			XMLProperty* prop;
+
+			prop = (*i)->property ("x");
+			sscanf (prop->value().c_str(), "%" PRIu32, &x);
+
+			prop = (*i)->property ("y");
+			sscanf (prop->value().c_str(), "%f", &y);
+			
+			_fade_out.add (x, y);
+		}
+	}
+
+	_fade_out.thaw ();
+
+	StateChanged (what_changed); /* EMIT SIGNAL */
+
+	return 0;
+}
+
+bool
+Crossfade::can_follow_overlap () const
+{
+	return !_fixed;
+}
+
+void
+Crossfade::set_follow_overlap (bool yn)
+{
+	if (yn == _follow_overlap || _fixed) {
+		return;
+	}
+
+	_follow_overlap = yn;
+
+	if (!yn) {
+		set_length (_short_xfade_length);
+	} else {
+		set_length (_out->first_frame() + _out->length() - _in->first_frame());
+	}
+
+	StateChanged (FollowOverlapChanged);
+}
+
+nframes_t
+Crossfade::set_length (nframes_t len)
+{
+	nframes_t limit;
+
+	switch (_anchor_point) {
+	case StartOfIn:
+		limit = _in->length();
+		break;
+
+	case EndOfIn:
+		limit = _in->length();
+		break;
+
+	case EndOfOut:
+		limit = _out->length();
+		break;
+		
+	}
+
+	len = min (limit, len);
+
+	double factor = len / (double) _length;
+
+	_in_update = true;
+	_fade_out.x_scale (factor);
+	_fade_in.x_scale (factor);
+	_in_update = false;
+	
+	_length = len;
+
+	StateChanged (LengthChanged);
+
+	return len;
+}
+
+nframes_t
+Crossfade::overlap_length () const
+{
+	if (_fixed) {
+		return _length;
+	}
+	return _out->first_frame() + _out->length() - _in->first_frame();
+}
+
+void
+Crossfade::set_short_xfade_length (nframes_t n)
+{
+	_short_xfade_length = n;
+}
+
+void
+Crossfade::invalidate ()
+{
+	Invalidated (shared_from_this ()); /* EMIT SIGNAL */
+}