re-reference regions during uncombine - #5979
[ardour.git] / libs / ardour / playlist.cc
index 4d7e63599ff32001d4e91746e2361a91f171bdf2..c8cca64b782d69bdb899dfbe6782b88924ad59fb 100644 (file)
 
 #include <stdint.h>
 #include <set>
-#include <fstream>
 #include <algorithm>
-#include <unistd.h>
-#include <cerrno>
 #include <string>
-#include <climits>
 
 #include <boost/lexical_cast.hpp>
 
 #include "pbd/convert.h"
-#include "pbd/failed_constructor.h"
-#include "pbd/stacktrace.h"
 #include "pbd/stateful_diff_command.h"
 #include "pbd/xml++.h"
 
@@ -53,9 +47,9 @@ using namespace ARDOUR;
 using namespace PBD;
 
 namespace ARDOUR {
-namespace Properties {
-PBD::PropertyDescriptor<bool> regions;
-}
+       namespace Properties {
+               PBD::PropertyDescriptor<bool> regions;
+       }
 }
 
 struct ShowMeTheList {
@@ -178,6 +172,7 @@ Playlist::Playlist (boost::shared_ptr<const Playlist> other, string namestr, boo
        in_set_state--;
 
        _splicing  = other->_splicing;
+       _rippling  = other->_rippling;
        _nudging   = other->_nudging;
        _edit_mode = other->_edit_mode;
 
@@ -187,9 +182,6 @@ Playlist::Playlist (boost::shared_ptr<const Playlist> other, string namestr, boo
        in_partition = false;
        subcnt = 0;
        _frozen = other->_frozen;
-
-       layer_op_counter = other->layer_op_counter;
-       freeze_length = other->freeze_length;
 }
 
 Playlist::Playlist (boost::shared_ptr<const Playlist> other, framepos_t start, framecnt_t cnt, string str, bool hide)
@@ -198,7 +190,7 @@ Playlist::Playlist (boost::shared_ptr<const Playlist> other, framepos_t start, f
        , _type(other->_type)
        , _orig_track_id (other->_orig_track_id)
 {
-       RegionLock rlock2 (const_cast<Playlist*> (other.get()));
+       RegionReadLock rlock2 (const_cast<Playlist*> (other.get()));
 
        framepos_t end = start + cnt - 1;
 
@@ -214,35 +206,35 @@ Playlist::Playlist (boost::shared_ptr<const Playlist> other, framepos_t start, f
                framepos_t position = 0;
                framecnt_t len = 0;
                string    new_name;
-               OverlapType overlap;
+               Evoral::OverlapType overlap;
 
                region = *i;
 
                overlap = region->coverage (start, end);
 
                switch (overlap) {
-               case OverlapNone:
+               case Evoral::OverlapNone:
                        continue;
 
-               case OverlapInternal:
+               case Evoral::OverlapInternal:
                        offset = start - region->position();
                        position = 0;
                        len = cnt;
                        break;
 
-               case OverlapStart:
+               case Evoral::OverlapStart:
                        offset = 0;
                        position = region->position() - start;
                        len = end - region->position();
                        break;
 
-               case OverlapEnd:
+               case Evoral::OverlapEnd:
                        offset = start - region->position();
                        position = 0;
                        len = region->length() - offset;
                        break;
 
-               case OverlapExternal:
+               case Evoral::OverlapExternal:
                        offset = 0;
                        position = region->position() - start;
                        len = region->length();
@@ -257,12 +249,17 @@ Playlist::Playlist (boost::shared_ptr<const Playlist> other, framepos_t start, f
                plist.add (Properties::length, len);
                plist.add (Properties::name, new_name);
                plist.add (Properties::layer, region->layer());
+               plist.add (Properties::layering_index, region->layering_index());
 
-               new_region = RegionFactory::RegionFactory::create (region, plist);
+               new_region = RegionFactory::create (region, plist);
 
                add_region_internal (new_region, position);
        }
 
+       //keep track of any dead space at end (for pasting into Ripple or Splice mode)
+       //at the end of construction, any length of cnt beyond the extents of the regions is end_space
+       _end_space = cnt - (get_extent().second - get_extent().first);
+
        in_set_state--;
        first_set_state = false;
 }
@@ -289,10 +286,10 @@ Playlist::release ()
 void
 Playlist::copy_regions (RegionList& newlist) const
 {
-       RegionLock rlock (const_cast<Playlist *> (this));
+       RegionReadLock rlock (const_cast<Playlist *> (this));
 
        for (RegionList::const_iterator i = regions.begin(); i != regions.end(); ++i) {
-               newlist.push_back (RegionFactory::RegionFactory::create (*i, true));
+               newlist.push_back (RegionFactory::create (*i, true));
        }
 }
 
@@ -310,19 +307,19 @@ Playlist::init (bool hide)
        _refcnt = 0;
        _hidden = hide;
        _splicing = false;
+       _rippling = false;
        _shuffling = false;
        _nudging = false;
        in_set_state = 0;
-       in_update = false;
+       in_undo = false;
        _edit_mode = Config->get_edit_mode();
        in_flush = false;
        in_partition = false;
        subcnt = 0;
        _frozen = false;
-       layer_op_counter = 0;
-       freeze_length = 0;
+       _capture_insertion_underway = false;
        _combine_ops = 0;
-       _relayer_suspended = false;
+       _end_space = 0;
 
        _session.history().BeginUndoRedo.connect_same_thread (*this, boost::bind (&Playlist::begin_undo, this));
        _session.history().EndUndoRedo.connect_same_thread (*this, boost::bind (&Playlist::end_undo, this));
@@ -335,7 +332,7 @@ Playlist::~Playlist ()
        DEBUG_TRACE (DEBUG::Destruction, string_compose ("Playlist %1 destructor\n", _name));
 
        {
-               RegionLock rl (this);
+               RegionReadLock rl (this);
 
                for (set<boost::shared_ptr<Region> >::iterator i = all_regions.begin(); i != all_regions.end(); ++i) {
                        (*i)->set_playlist (boost::shared_ptr<Playlist>());
@@ -402,7 +399,7 @@ Playlist::set_name (const string& str)
 void
 Playlist::begin_undo ()
 {
-       in_update = true;
+       in_undo = true;
        freeze ();
 }
 
@@ -410,7 +407,7 @@ void
 Playlist::end_undo ()
 {
        thaw (true);
-       in_update = false;
+       in_undo = false;
 }
 
 void
@@ -433,7 +430,6 @@ void
 Playlist::delay_notifications ()
 {
        g_atomic_int_inc (&block_notifications);
-       freeze_length = _get_extent().second;
 }
 
 /** @param from_undo true if this release is triggered by the end of an undo on this playlist */
@@ -488,8 +484,6 @@ Playlist::notify_region_moved (boost::shared_ptr<Region> r)
 {
        Evoral::RangeMove<framepos_t> const move (r->last_position (), r->length (), r->position ());
 
-       /* We could timestamp the region's layer op here, but we're doing it in region_bounds_changed */
-
        if (holding_state ()) {
 
                pending_range_moves.push_back (move);
@@ -506,8 +500,6 @@ Playlist::notify_region_moved (boost::shared_ptr<Region> r)
 void
 Playlist::notify_region_start_trimmed (boost::shared_ptr<Region> r)
 {
-       timestamp_layer_op (LayerOpBoundsChange, r);
-
        if (r->position() >= r->last_position()) {
                /* trimmed shorter */
                return;
@@ -531,8 +523,6 @@ Playlist::notify_region_start_trimmed (boost::shared_ptr<Region> r)
 void
 Playlist::notify_region_end_trimmed (boost::shared_ptr<Region> r)
 {
-       timestamp_layer_op (LayerOpBoundsChange, r);
-
        if (r->length() < r->last_length()) {
                /* trimmed shorter */
        }
@@ -559,8 +549,6 @@ Playlist::notify_region_added (boost::shared_ptr<Region> r)
           as though it could be.
        */
 
-       timestamp_layer_op (LayerOpAdd, r);
-
        if (holding_state()) {
                pending_adds.insert (r);
                pending_contents_change = true;
@@ -569,7 +557,6 @@ Playlist::notify_region_added (boost::shared_ptr<Region> r)
                pending_contents_change = false;
                RegionAdded (boost::weak_ptr<Region> (r)); /* EMIT SIGNAL */
                ContentsChanged (); /* EMIT SIGNAL */
-               relayer (r);
        }
 }
 
@@ -577,9 +564,8 @@ Playlist::notify_region_added (boost::shared_ptr<Region> r)
 void
 Playlist::flush_notifications (bool from_undo)
 {
-       set<boost::shared_ptr<Region> > dependent_checks_needed;
        set<boost::shared_ptr<Region> >::iterator s;
-       uint32_t regions_changed = false;
+       bool regions_changed = false;
 
        if (in_flush) {
                return;
@@ -587,41 +573,47 @@ Playlist::flush_notifications (bool from_undo)
 
        in_flush = true;
 
-       /* We have:
+       if (!pending_bounds.empty() || !pending_removes.empty() || !pending_adds.empty()) {
+               regions_changed = true;
+       }
 
-          pending_bounds:  regions whose bounds position and/or length changes
-          pending_removes: regions which were removed
-          pending_adds:    regions which were added
-          pending_length:  true if the playlist length might have changed
-          pending_contents_change: true if there was almost any change in the playlist
-          pending_range_moves: details of periods of time that have been moved about (when regions have been moved)
+       /* XXX: it'd be nice if we could use pending_bounds for
+          RegionsExtended and RegionsMoved.
+       */
 
+       /* we have no idea what order the regions ended up in pending
+          bounds (it could be based on selection order, for example).
+          so, to preserve layering in the "most recently moved is higher"
+          model, sort them by existing layer, then timestamp them.
        */
 
-       if (!pending_bounds.empty() || !pending_removes.empty() || !pending_adds.empty()) {
-               regions_changed = true;
-       }
+       // RegionSortByLayer cmp;
+       // pending_bounds.sort (cmp);
 
-       /* Make a list of regions that need relayering */
-       RegionList regions_to_relayer;
+       list<Evoral::Range<framepos_t> > crossfade_ranges;
 
        for (RegionList::iterator r = pending_bounds.begin(); r != pending_bounds.end(); ++r) {
-               regions_to_relayer.push_back (*r);
-               dependent_checks_needed.insert (*r);
+               crossfade_ranges.push_back ((*r)->last_range ());
+               crossfade_ranges.push_back ((*r)->range ());
        }
 
        for (s = pending_removes.begin(); s != pending_removes.end(); ++s) {
+               crossfade_ranges.push_back ((*s)->range ());
                remove_dependents (*s);
                RegionRemoved (boost::weak_ptr<Region> (*s)); /* EMIT SIGNAL */
        }
-
+       
        for (s = pending_adds.begin(); s != pending_adds.end(); ++s) {
-                /* don't emit RegionAdded signal until relayering is done,
-                   so that the region is fully setup by the time
-                   anyone hear's that its been added
-                */
-                dependent_checks_needed.insert (*s);
-        }
+               crossfade_ranges.push_back ((*s)->range ());
+               /* don't emit RegionAdded signal until relayering is done,
+                  so that the region is fully setup by the time
+                  anyone hears that its been added
+               */
+       }
+
+       if (((regions_changed || pending_contents_change) && !in_set_state) || pending_layering) {
+               relayer ();
+       }
 
         if (regions_changed || pending_contents_change) {
                 pending_contents_change = false;
@@ -631,14 +623,14 @@ Playlist::flush_notifications (bool from_undo)
         for (s = pending_adds.begin(); s != pending_adds.end(); ++s) {
                 (*s)->clear_changes ();
                 RegionAdded (boost::weak_ptr<Region> (*s)); /* EMIT SIGNAL */
-                regions_to_relayer.push_back (*s);
         }
 
-        for (s = dependent_checks_needed.begin(); s != dependent_checks_needed.end(); ++s) {
-                check_dependents (*s, false);
-        }
+        coalesce_and_check_crossfades (crossfade_ranges);
 
         if (!pending_range_moves.empty ()) {
+                /* We don't need to check crossfades for these as pending_bounds has
+                   already covered it.
+                */
                 RangesMoved (pending_range_moves, from_undo);
         }
 
@@ -646,10 +638,6 @@ Playlist::flush_notifications (bool from_undo)
                 RegionsExtended (pending_region_extensions);
         }
 
-        if (!regions_to_relayer.empty ()) {
-                relayer (regions_to_relayer);
-        }
-
         clear_pending ();
 
         in_flush = false;
@@ -670,10 +658,11 @@ Playlist::flush_notifications (bool from_undo)
    PLAYLIST OPERATIONS
   *************************************************************/
 
+/** Note: this calls set_layer (..., DBL_MAX) so it will reset the layering index of region */
  void
  Playlist::add_region (boost::shared_ptr<Region> region, framepos_t position, float times, bool auto_partition)
  {
-        RegionLock rlock (this);
+        RegionWriteLock rlock (this);
         times = fabs (times);
 
         int itimes = (int) floor (times);
@@ -686,6 +675,7 @@ Playlist::flush_notifications (bool from_undo)
 
         if (itimes >= 1) {
                 add_region_internal (region, pos);
+                set_layer (region, DBL_MAX);
                 pos += region->length();
                 --itimes;
         }
@@ -698,6 +688,7 @@ Playlist::flush_notifications (bool from_undo)
         for (int i = 0; i < itimes; ++i) {
                 boost::shared_ptr<Region> copy = RegionFactory::create (region, true);
                 add_region_internal (copy, pos);
+                set_layer (copy, DBL_MAX);
                 pos += region->length();
         }
 
@@ -718,16 +709,17 @@ Playlist::flush_notifications (bool from_undo)
 
                         boost::shared_ptr<Region> sub = RegionFactory::create (region, plist);
                         add_region_internal (sub, pos);
+                        set_layer (sub, DBL_MAX);
                 }
         }
 
-        possibly_splice_unlocked (position, (pos + length) - position, boost::shared_ptr<Region>());
+        possibly_splice_unlocked (position, (pos + length) - position, region);
  }
 
  void
  Playlist::set_region_ownership ()
  {
-        RegionLock rl (this);
+        RegionWriteLock rl (this);
         RegionList::iterator i;
         boost::weak_ptr<Playlist> pl (shared_from_this());
 
@@ -757,14 +749,15 @@ Playlist::flush_notifications (bool from_undo)
 
         possibly_splice_unlocked (position, region->length(), region);
 
+        if (!holding_state ()) {
+                /* layers get assigned from XML state, and are not reset during undo/redo */
+                relayer ();
+        }
+
         /* we need to notify the existence of new region before checking dependents. Ick. */
 
         notify_region_added (region);
 
-        if (!holding_state ()) {
-                check_dependents (region, false);
-        }
-
         region->PropertyChanged.connect_same_thread (region_state_changed_connections, boost::bind (&Playlist::region_changed_proxy, this, _1, boost::weak_ptr<Region> (region)));
 
         return true;
@@ -773,13 +766,14 @@ Playlist::flush_notifications (bool from_undo)
  void
  Playlist::replace_region (boost::shared_ptr<Region> old, boost::shared_ptr<Region> newr, framepos_t pos)
  {
-        RegionLock rlock (this);
+        RegionWriteLock rlock (this);
 
         bool old_sp = _splicing;
         _splicing = true;
 
         remove_region_internal (old);
         add_region_internal (newr, pos);
+        set_layer (newr, old->layer ());
 
         _splicing = old_sp;
 
@@ -789,7 +783,7 @@ Playlist::flush_notifications (bool from_undo)
  void
  Playlist::remove_region (boost::shared_ptr<Region> region)
  {
-        RegionLock rlock (this);
+        RegionWriteLock rlock (this);
         remove_region_internal (region);
  }
 
@@ -816,6 +810,7 @@ Playlist::flush_notifications (bool from_undo)
                         possibly_splice_unlocked (pos, -distance);
 
                         if (!holding_state ()) {
+                                relayer ();
                                 remove_dependents (region);
                         }
 
@@ -833,13 +828,13 @@ Playlist::flush_notifications (bool from_undo)
         if (Config->get_use_overlap_equivalency()) {
                 for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
                         if ((*i)->overlap_equivalent (other)) {
-                                results.push_back ((*i));
+                                results.push_back (*i);
                         }
                 }
         } else {
                 for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
                         if ((*i)->equivalent (other)) {
-                                results.push_back ((*i));
+                                results.push_back (*i);
                         }
                 }
         }
@@ -856,6 +851,17 @@ Playlist::flush_notifications (bool from_undo)
         }
  }
 
+ void
+ Playlist::get_source_equivalent_regions (boost::shared_ptr<Region> other, vector<boost::shared_ptr<Region> >& results)
+ {
+        for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
+
+                if ((*i) && (*i)->any_source_equivalent (other)) {
+                        results.push_back (*i);
+                }
+        }
+ }
+
  void
  Playlist::partition (framepos_t start, framepos_t end, bool cut)
  {
@@ -872,24 +878,20 @@ Playlist::flush_notifications (bool from_undo)
  *  start and end if cutting == true.  Regions that lie entirely within start and end are always
  *  removed.
  */
+
  void
  Playlist::partition_internal (framepos_t start, framepos_t end, bool cutting, RegionList& thawlist)
  {
         RegionList new_regions;
 
-        /* Don't relayer regions that are created during this operation; leave them
-           on the same region as the original.
-        */
-        suspend_relayer ();
-
         {
-                RegionLock rlock (this);
+                RegionWriteLock rlock (this);
 
                 boost::shared_ptr<Region> region;
                 boost::shared_ptr<Region> current;
                 string new_name;
                 RegionList::iterator tmp;
-                OverlapType overlap;
+                Evoral::OverlapType overlap;
                 framepos_t pos1, pos2, pos3, pos4;
 
                 in_partition = true;
@@ -925,7 +927,7 @@ Playlist::flush_notifications (bool from_undo)
                                 continue;
                         }
 
-                        if ((overlap = current->coverage (start, end)) == OverlapNone) {
+                        if ((overlap = current->coverage (start, end)) == Evoral::OverlapNone) {
                                 continue;
                         }
 
@@ -934,7 +936,7 @@ Playlist::flush_notifications (bool from_undo)
                         pos3 = end;
                         pos4 = current->last_frame();
 
-                        if (overlap == OverlapInternal) {
+                        if (overlap == Evoral::OverlapInternal) {
                                 /* split: we need 3 new regions, the front, middle and end.
                                    cut:   we need 2 regions, the front and end.
                                 */
@@ -960,7 +962,8 @@ Playlist::flush_notifications (bool from_undo)
                                         plist.add (Properties::start, current->start() + (pos2 - pos1));
                                         plist.add (Properties::length, pos3 - pos2);
                                         plist.add (Properties::name, new_name);
-                                        plist.add (Properties::layer, current->layer());
+                                        plist.add (Properties::layer, current->layer ());
+                                        plist.add (Properties::layering_index, current->layering_index ());
                                         plist.add (Properties::automatic, true);
                                         plist.add (Properties::left_of_split, true);
                                         plist.add (Properties::right_of_split, true);
@@ -979,7 +982,8 @@ Playlist::flush_notifications (bool from_undo)
                                 plist.add (Properties::start, current->start() + (pos3 - pos1));
                                 plist.add (Properties::length, pos4 - pos3);
                                 plist.add (Properties::name, new_name);
-                                plist.add (Properties::layer, current->layer());
+                                plist.add (Properties::layer, current->layer ());
+                                plist.add (Properties::layering_index, current->layering_index ());
                                 plist.add (Properties::automatic, true);
                                 plist.add (Properties::right_of_split, true);
 
@@ -994,7 +998,7 @@ Playlist::flush_notifications (bool from_undo)
                                 thawlist.push_back (current);
                                 current->cut_end (pos2 - 1);
 
-                        } else if (overlap == OverlapEnd) {
+                        } else if (overlap == Evoral::OverlapEnd) {
 
                                 /*
                                                               start           end
@@ -1017,7 +1021,8 @@ Playlist::flush_notifications (bool from_undo)
                                         plist.add (Properties::start, current->start() + (pos2 - pos1));
                                         plist.add (Properties::length, pos4 - pos2);
                                         plist.add (Properties::name, new_name);
-                                        plist.add (Properties::layer, current->layer());
+                                        plist.add (Properties::layer, current->layer ());
+                                        plist.add (Properties::layering_index, current->layering_index ());
                                         plist.add (Properties::automatic, true);
                                         plist.add (Properties::left_of_split, true);
 
@@ -1033,7 +1038,7 @@ Playlist::flush_notifications (bool from_undo)
                                 thawlist.push_back (current);
                                 current->cut_end (pos2 - 1);
 
-                        } else if (overlap == OverlapStart) {
+                        } else if (overlap == Evoral::OverlapStart) {
 
                                 /* split: we need 2 regions: the front and the end.
                                    cut: just trim current to skip the cut area
@@ -1060,7 +1065,8 @@ Playlist::flush_notifications (bool from_undo)
                                         plist.add (Properties::start, current->start());
                                         plist.add (Properties::length, pos3 - pos1);
                                         plist.add (Properties::name, new_name);
-                                        plist.add (Properties::layer, current->layer());
+                                        plist.add (Properties::layer, current->layer ());
+                                        plist.add (Properties::layering_index, current->layering_index ());
                                         plist.add (Properties::automatic, true);
                                         plist.add (Properties::right_of_split, true);
 
@@ -1075,7 +1081,7 @@ Playlist::flush_notifications (bool from_undo)
                                 current->suspend_property_changes ();
                                 thawlist.push_back (current);
                                 current->trim_front (pos3);
-                        } else if (overlap == OverlapExternal) {
+                        } else if (overlap == Evoral::OverlapExternal) {
 
                                 /* split: no split required.
                                    cut: remove the region.
@@ -1104,11 +1110,9 @@ Playlist::flush_notifications (bool from_undo)
                 in_partition = false;
         }
 
-        for (RegionList::iterator i = new_regions.begin(); i != new_regions.end(); ++i) {
-                check_dependents (*i, false);
-        }
-
-        resume_relayer ();
+       //keep track of any dead space at end (for pasting into Ripple or Splice mode)
+       framepos_t wanted_length = end-start;
+       _end_space = wanted_length - get_extent().second-get_extent().first;
  }
 
  boost::shared_ptr<Playlist>
@@ -1193,7 +1197,8 @@ Playlist::flush_notifications (bool from_undo)
         new_name += '.';
         new_name += buf;
 
-        cnt = min (_get_extent().second - start, cnt);
+       // cnt = min (_get_extent().second - start, cnt);  (We need the full range length when copy/pasting in Ripple.  Why was this limit here?  It's not in CUT... )
+
         return PlaylistFactory::create (shared_from_this(), start, cnt, new_name, result_is_hidden);
  }
 
@@ -1203,26 +1208,28 @@ Playlist::flush_notifications (bool from_undo)
         times = fabs (times);
 
         {
-                RegionLock rl1 (this);
-                RegionLock rl2 (other.get());
+                RegionReadLock rl2 (other.get());
 
                 int itimes = (int) floor (times);
                 framepos_t pos = position;
                 framecnt_t const shift = other->_get_extent().second;
-                layer_t top_layer = regions.size();
+                layer_t top = top_layer ();
 
-                while (itimes--) {
-                        for (RegionList::iterator i = other->regions.begin(); i != other->regions.end(); ++i) {
-                                boost::shared_ptr<Region> copy_of_region = RegionFactory::create (*i, true);
-
-                                /* put these new regions on top of all existing ones, but preserve
-                                   the ordering they had in the original playlist.
-                                */
-
-                                copy_of_region->set_layer (copy_of_region->layer() + top_layer);
-                                add_region_internal (copy_of_region, (*i)->position() + pos);
+                {
+                        RegionWriteLock rl1 (this);
+                        while (itimes--) {
+                                for (RegionList::iterator i = other->regions.begin(); i != other->regions.end(); ++i) {
+                                        boost::shared_ptr<Region> copy_of_region = RegionFactory::create (*i, true);
+                                        
+                                        /* put these new regions on top of all existing ones, but preserve
+                                           the ordering they had in the original playlist.
+                                        */
+                                        
+                                        add_region_internal (copy_of_region, (*i)->position() + pos);
+                                        set_layer (copy_of_region, copy_of_region->layer() + top);
+                                }
+                                pos += shift;
                         }
-                        pos += shift;
                 }
         }
 
@@ -1235,13 +1242,14 @@ Playlist::flush_notifications (bool from_undo)
  {
         times = fabs (times);
 
-        RegionLock rl (this);
+        RegionWriteLock rl (this);
         int itimes = (int) floor (times);
         framepos_t pos = position + 1;
 
         while (itimes--) {
                 boost::shared_ptr<Region> copy = RegionFactory::create (region, true);
                 add_region_internal (copy, pos);
+                set_layer (copy, DBL_MAX);
                 pos += region->length();
         }
 
@@ -1259,6 +1267,7 @@ Playlist::flush_notifications (bool from_undo)
 
                         boost::shared_ptr<Region> sub = RegionFactory::create (region, plist);
                         add_region_internal (sub, pos);
+                        set_layer (sub, DBL_MAX);
                 }
         }
  }
@@ -1266,7 +1275,7 @@ Playlist::flush_notifications (bool from_undo)
  void
  Playlist::shift (framepos_t at, frameoffset_t distance, bool move_intersected, bool ignore_music_glue)
  {
-        RegionLock rlock (this);
+        RegionWriteLock rlock (this);
         RegionList copy (regions.rlist());
         RegionList fixup;
 
@@ -1305,7 +1314,7 @@ Playlist::flush_notifications (bool from_undo)
  void
  Playlist::split (framepos_t at)
  {
-        RegionLock rlock (this);
+        RegionWriteLock rlock (this);
         RegionList copy (regions.rlist());
 
         /* use a copy since this operation can modify the region list
@@ -1319,7 +1328,7 @@ Playlist::flush_notifications (bool from_undo)
  void
  Playlist::split_region (boost::shared_ptr<Region> region, framepos_t playlist_position)
  {
-        RegionLock rl (this);
+        RegionWriteLock rl (this);
         _split_region (region, playlist_position);
  }
 
@@ -1359,6 +1368,8 @@ Playlist::flush_notifications (bool from_undo)
                 plist.add (Properties::length, before);
                 plist.add (Properties::name, before_name);
                 plist.add (Properties::left_of_split, true);
+                plist.add (Properties::layering_index, region->layering_index ());
+                plist.add (Properties::layer, region->layer ());
 
                 /* note: we must use the version of ::create with an offset here,
                    since it supplies that offset to the Region constructor, which
@@ -1376,6 +1387,8 @@ Playlist::flush_notifications (bool from_undo)
                 plist.add (Properties::length, after);
                 plist.add (Properties::name, after_name);
                 plist.add (Properties::right_of_split, true);
+                plist.add (Properties::layering_index, region->layering_index ());
+                plist.add (Properties::layer, region->layer ());
 
                 /* same note as above */
                 right = RegionFactory::create (region, before, plist);
@@ -1383,9 +1396,6 @@ Playlist::flush_notifications (bool from_undo)
 
         add_region_internal (left, region->position());
         add_region_internal (right, region->position() + before);
-
-        finalize_split_region (region, left, right);
-
         remove_region_internal (region);
 
         _splicing = old_sp;
@@ -1401,7 +1411,7 @@ Playlist::flush_notifications (bool from_undo)
 
         if (_edit_mode == Splice) {
                 splice_locked (at, distance, exclude);
-        }
+        } 
  }
 
  void
@@ -1421,7 +1431,7 @@ Playlist::flush_notifications (bool from_undo)
  Playlist::splice_locked (framepos_t at, framecnt_t distance, boost::shared_ptr<Region> exclude)
  {
         {
-                RegionLock rl (this);
+                RegionWriteLock rl (this);
                 core_splice (at, distance, exclude);
         }
  }
@@ -1458,19 +1468,68 @@ Playlist::flush_notifications (bool from_undo)
         _splicing = false;
 
         notify_contents_changed ();
- }
+}
 
- void
- Playlist::region_bounds_changed (const PropertyChange& what_changed, boost::shared_ptr<Region> region)
- {
-        if (in_set_state || _splicing || _nudging || _shuffling) {
+void
+Playlist::ripple_locked (framepos_t at, framecnt_t distance, RegionList *exclude)
+{
+       {
+               RegionWriteLock rl (this);
+               core_ripple (at, distance, exclude);
+       }
+}
+
+void
+Playlist::ripple_unlocked (framepos_t at, framecnt_t distance, RegionList *exclude)
+{
+       core_ripple (at, distance, exclude);
+}
+
+void
+Playlist::core_ripple (framepos_t at, framecnt_t distance, RegionList *exclude)
+{
+       if (distance == 0) {
+               return;
+       }
+
+       _rippling = true;
+       RegionListProperty copy = regions;
+       for (RegionList::iterator i = copy.begin(); i != copy.end(); ++i) {
+               assert (i != copy.end());
+
+               if (exclude) {
+                       if (std::find(exclude->begin(), exclude->end(), (*i)) != exclude->end()) {
+                               continue;
+                       }
+               }
+
+               if ((*i)->position() >= at) {
+                       framepos_t new_pos = (*i)->position() + distance;
+                       framepos_t limit = max_framepos - (*i)->length();
+                       if (new_pos < 0) {
+                               new_pos = 0;
+                       } else if (new_pos >= limit ) {
+                               new_pos = limit;
+                       } 
+                               
+                       (*i)->set_position (new_pos);
+               }
+       }
+
+       _rippling = false;
+       notify_contents_changed ();
+}
+
+
+void
+Playlist::region_bounds_changed (const PropertyChange& what_changed, boost::shared_ptr<Region> region)
+{
+        if (in_set_state || _splicing || _rippling || _nudging || _shuffling) {
                 return;
         }
 
         if (what_changed.contains (Properties::position)) {
 
-                timestamp_layer_op (LayerOpBoundsChange, region);
-                
                 /* remove it from the list then add it back in
                    the right place again.
                 */
@@ -1511,8 +1570,11 @@ Playlist::flush_notifications (bool from_undo)
                         pending_bounds.push_back (region);
                 } else {
                         notify_contents_changed ();
-                        relayer (region);
-                        check_dependents (region, false);
+                        relayer ();
+                        list<Evoral::Range<framepos_t> > xf;
+                        xf.push_back (Evoral::Range<framepos_t> (region->last_range()));
+                        xf.push_back (Evoral::Range<framepos_t> (region->range()));
+                        coalesce_and_check_crossfades (xf);
                 }
         }
  }
@@ -1559,10 +1621,6 @@ Playlist::flush_notifications (bool from_undo)
                 save = !(_splicing || _nudging);
         }
 
-        if (what_changed.contains (our_interests) && !what_changed.contains (pos_and_length)) {
-                check_dependents (region, false);
-        }
-
         if (what_changed.contains (Properties::position) && !what_changed.contains (Properties::length)) {
                 notify_region_moved (region);
         } else if (!what_changed.contains (Properties::position) && what_changed.contains (Properties::length)) {
@@ -1571,6 +1629,10 @@ Playlist::flush_notifications (bool from_undo)
                 notify_region_start_trimmed (region);
         }
 
+        /* don't notify about layer changes, since we are the only object that can initiate
+           them, and we notify in ::relayer()
+        */
+
         if (what_changed.contains (our_interests)) {
                 save = true;
         }
@@ -1581,7 +1643,7 @@ Playlist::flush_notifications (bool from_undo)
  void
  Playlist::drop_regions ()
  {
-        RegionLock rl (this);
+        RegionWriteLock rl (this);
         regions.clear ();
         all_regions.clear ();
  }
@@ -1589,7 +1651,7 @@ Playlist::flush_notifications (bool from_undo)
  void
  Playlist::sync_all_regions_with_regions ()
  {
-        RegionLock rl (this);
+        RegionWriteLock rl (this);
 
         all_regions.clear ();
 
@@ -1602,7 +1664,7 @@ Playlist::flush_notifications (bool from_undo)
  Playlist::clear (bool with_signals)
  {
         {
-                RegionLock rl (this);
+                RegionWriteLock rl (this);
 
                 region_state_changed_connections.drop_connections ();
 
@@ -1634,18 +1696,17 @@ Playlist::flush_notifications (bool from_undo)
   FINDING THINGS
   **********************************************************************/
 
- Playlist::RegionList *
- Playlist::regions_at (framepos_t frame)
-
- {
-        RegionLock rlock (this);
-        return find_regions_at (frame);
- }
+boost::shared_ptr<RegionList>
+Playlist::regions_at (framepos_t frame)
+{
+       RegionReadLock rlock (this);
+       return find_regions_at (frame);
+}
 
  uint32_t
  Playlist::count_regions_at (framepos_t frame) const
  {
-        RegionLock rlock (const_cast<Playlist*>(this));
+        RegionReadLock rlock (const_cast<Playlist*>(this));
         uint32_t cnt = 0;
 
         for (RegionList::const_iterator i = regions.begin(); i != regions.end(); ++i) {
@@ -1661,8 +1722,8 @@ Playlist::flush_notifications (bool from_undo)
  Playlist::top_region_at (framepos_t frame)
 
  {
-        RegionLock rlock (this);
-        RegionList *rlist = find_regions_at (frame);
+        RegionReadLock rlock (this);
+        boost::shared_ptr<RegionList> rlist = find_regions_at (frame);
         boost::shared_ptr<Region> region;
 
         if (rlist->size()) {
@@ -1671,7 +1732,6 @@ Playlist::flush_notifications (bool from_undo)
                 region = rlist->back();
         }
 
-        delete rlist;
         return region;
  }
 
@@ -1679,8 +1739,8 @@ Playlist::flush_notifications (bool from_undo)
  Playlist::top_unmuted_region_at (framepos_t frame)
 
  {
-        RegionLock rlock (this);
-        RegionList *rlist = find_regions_at (frame);
+        RegionReadLock rlock (this);
+        boost::shared_ptr<RegionList> rlist = find_regions_at (frame);
 
         for (RegionList::iterator i = rlist->begin(); i != rlist->end(); ) {
 
@@ -1702,301 +1762,204 @@ Playlist::flush_notifications (bool from_undo)
                 region = rlist->back();
         }
 
-        delete rlist;
         return region;
  }
 
- Playlist::RegionList*
- Playlist::regions_to_read (framepos_t start, framepos_t end)
- {
-        /* Caller must hold lock */
-
-        RegionList covering;
-        set<framepos_t> to_check;
-        set<boost::shared_ptr<Region> > unique;
-
-        to_check.insert (start);
-        to_check.insert (end);
-
-        DEBUG_TRACE (DEBUG::AudioPlayback, ">>>>> REGIONS TO READ\n");
-
-        for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
-
-                /* find all/any regions that span start+end */
-
-                switch ((*i)->coverage (start, end)) {
-                case OverlapNone:
-                        break;
-
-                case OverlapInternal:
-                        covering.push_back (*i);
-                        DEBUG_TRACE (DEBUG::AudioPlayback, string_compose ("toread: will cover %1 (OInternal)\n", (*i)->name()));
-                        break;
-
-                case OverlapStart:
-                        to_check.insert ((*i)->position());
-                        if ((*i)->position() != 0) {
-                                to_check.insert ((*i)->position()-1);
-                        }
-                        DEBUG_TRACE (DEBUG::AudioPlayback, string_compose ("toread: will check %1 for %2\n", (*i)->position(), (*i)->name()));
-                        covering.push_back (*i);
-                        break;
-
-                case OverlapEnd:
-                        to_check.insert ((*i)->last_frame());
-                        to_check.insert ((*i)->last_frame()+1);
-                        DEBUG_TRACE (DEBUG::AudioPlayback, string_compose ("toread: will cover %1 (OEnd)\n", (*i)->name()));
-                        DEBUG_TRACE (DEBUG::AudioPlayback, string_compose ("\ttoread: will check %1 for %2\n", (*i)->last_frame(), (*i)->name()));
-                        DEBUG_TRACE (DEBUG::AudioPlayback, string_compose ("\ttoread: will check %1 for %2\n", (*i)->last_frame(), (*i)->name()));
-                        covering.push_back (*i);
-                        break;
-
-                case OverlapExternal:
-                        covering.push_back (*i);
-                        to_check.insert ((*i)->position());
-                        if ((*i)->position() != 0) {
-                                to_check.insert ((*i)->position()-1);
-                        }
-                        to_check.insert ((*i)->last_frame());
-                        to_check.insert ((*i)->last_frame()+1);
-                        DEBUG_TRACE (DEBUG::AudioPlayback, string_compose ("toread: will cover %1 (OExt)\n", (*i)->name()));
-                        DEBUG_TRACE (DEBUG::AudioPlayback, string_compose ("\ttoread: will check %1 for %2\n", (*i)->position(), (*i)->name()));
-                        DEBUG_TRACE (DEBUG::AudioPlayback, string_compose ("\ttoread: will check %1 for %2\n", (*i)->last_frame(), (*i)->name()));
-                        break;
-                }
-
-                /* don't go too far */
-
-                if ((*i)->position() > end) {
-                        break;
-                }
-        }
-
-        RegionList* rlist = new RegionList;
-
-        /* find all the regions that cover each position .... */
-
-        if (covering.size() == 1) {
-
-                rlist->push_back (covering.front());
-                DEBUG_TRACE (DEBUG::AudioPlayback, string_compose ("Just one covering region (%1)\n", covering.front()->name()));
-
-        } else {
-
-                RegionList here;
-                for (set<framepos_t>::iterator t = to_check.begin(); t != to_check.end(); ++t) {
-
-                        here.clear ();
-
-                        DEBUG_TRACE (DEBUG::AudioPlayback, string_compose ("++++ Considering %1\n", *t));
-
-                        for (RegionList::iterator x = covering.begin(); x != covering.end(); ++x) {
-
-                                if ((*x)->covers (*t)) {
-                                        here.push_back (*x);
-                                        DEBUG_TRACE (DEBUG::AudioPlayback, string_compose ("region %1 covers %2\n",
-                                                                                           (*x)->name(),
-                                                                                           (*t)));
-                                } else {
-                                        DEBUG_TRACE (DEBUG::AudioPlayback, string_compose ("region %1 does NOT covers %2\n",
-                                                                                           (*x)->name(),
-                                                                                           (*t)));
-                                }
-
-                        }
-
-                        RegionSortByLayer cmp;
-                        here.sort (cmp);
-
-                        /* ... and get the top/transparent regions at "here" */
-
-                        for (RegionList::reverse_iterator c = here.rbegin(); c != here.rend(); ++c) {
-
-                                unique.insert (*c);
-
-                                if ((*c)->opaque()) {
-
-                                        /* the other regions at this position are hidden by this one */
-                                        DEBUG_TRACE (DEBUG::AudioPlayback, string_compose ("%1 is opaque, ignore all others\n",
-                                                                                           (*c)->name()));
-                                        break;
-                                }
-                        }
-                }
-
-                for (set<boost::shared_ptr<Region> >::iterator s = unique.begin(); s != unique.end(); ++s) {
-                        rlist->push_back (*s);
-                }
-
-                if (rlist->size() > 1) {
-                        /* now sort by time order */
-
-                        RegionSortByPosition cmp;
-                        rlist->sort (cmp);
-                }
-        }
-
-        DEBUG_TRACE (DEBUG::AudioPlayback, string_compose ("<<<<< REGIONS TO READ returns %1\n", rlist->size()));
-
-        return rlist;
- }
-
- Playlist::RegionList *
- Playlist::find_regions_at (framepos_t frame)
- {
-        /* Caller must hold lock */
-
-        RegionList *rlist = new RegionList;
-
-        for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
-                if ((*i)->covers (frame)) {
-                        rlist->push_back (*i);
-                }
-        }
-
-        return rlist;
- }
-
- Playlist::RegionList *
- Playlist::regions_touched (framepos_t start, framepos_t end)
- {
-        RegionLock rlock (this);
-        RegionList *rlist = new RegionList;
-
-        for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
-                if ((*i)->coverage (start, end) != OverlapNone) {
-                        rlist->push_back (*i);
-                }
-        }
-
-        return rlist;
- }
-
- framepos_t
- Playlist::find_next_transient (framepos_t from, int dir)
- {
-        RegionLock rlock (this);
-        AnalysisFeatureList points;
-        AnalysisFeatureList these_points;
-
-        for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
-                if (dir > 0) {
-                        if ((*i)->last_frame() < from) {
-                                continue;
-                        }
-                } else {
-                        if ((*i)->first_frame() > from) {
-                                continue;
-                        }
-                }
-
-                (*i)->get_transients (these_points);
-
-                /* add first frame, just, err, because */
-
-                these_points.push_back ((*i)->first_frame());
-
-                points.insert (points.end(), these_points.begin(), these_points.end());
-                these_points.clear ();
-        }
-
-        if (points.empty()) {
-                return -1;
-        }
-
-        TransientDetector::cleanup_transients (points, _session.frame_rate(), 3.0);
-        bool reached = false;
-
-        if (dir > 0) {
-                for (AnalysisFeatureList::iterator x = points.begin(); x != points.end(); ++x) {
-                        if ((*x) >= from) {
-                                reached = true;
-                        }
-
-                        if (reached && (*x) > from) {
-                                return *x;
-                        }
-                }
-        } else {
-                for (AnalysisFeatureList::reverse_iterator x = points.rbegin(); x != points.rend(); ++x) {
-                        if ((*x) <= from) {
-                                reached = true;
-                        }
-
-                        if (reached && (*x) < from) {
-                                return *x;
-                        }
-                }
-        }
-
-        return -1;
- }
-
- boost::shared_ptr<Region>
- Playlist::find_next_region (framepos_t frame, RegionPoint point, int dir)
- {
-        RegionLock rlock (this);
-        boost::shared_ptr<Region> ret;
-        framepos_t closest = max_framepos;
-
-        bool end_iter = false;
-
-        for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
+boost::shared_ptr<RegionList>
+Playlist::find_regions_at (framepos_t frame)
+{
+       /* Caller must hold lock */
+       
+       boost::shared_ptr<RegionList> rlist (new RegionList);
+       
+       for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
+               if ((*i)->covers (frame)) {
+                       rlist->push_back (*i);
+               }
+       }
+       
+       return rlist;
+}
 
-                if(end_iter) break;
+boost::shared_ptr<RegionList>
+Playlist::regions_with_start_within (Evoral::Range<framepos_t> range)
+{
+       RegionReadLock rlock (this);
+       boost::shared_ptr<RegionList> rlist (new RegionList);
 
-                frameoffset_t distance;
-                boost::shared_ptr<Region> r = (*i);
-                framepos_t pos = 0;
+       for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
+               if ((*i)->first_frame() >= range.from && (*i)->first_frame() <= range.to) {
+                       rlist->push_back (*i);
+               }
+       }
 
-                switch (point) {
-                case Start:
-                        pos = r->first_frame ();
-                        break;
-                case End:
-                        pos = r->last_frame ();
-                        break;
-                case SyncPoint:
-                        pos = r->sync_position ();
-                        break;
-                }
+       return rlist;
+}
 
-                switch (dir) {
-                case 1: /* forwards */
+boost::shared_ptr<RegionList>
+Playlist::regions_with_end_within (Evoral::Range<framepos_t> range)
+{
+       RegionReadLock rlock (this);
+       boost::shared_ptr<RegionList> rlist (new RegionList);
 
-                        if (pos > frame) {
-                                if ((distance = pos - frame) < closest) {
-                                        closest = distance;
-                                        ret = r;
-                                        end_iter = true;
-                                }
-                        }
+       for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
+               if ((*i)->last_frame() >= range.from && (*i)->last_frame() <= range.to) {
+                       rlist->push_back (*i);
+               }
+       }
 
-                        break;
+       return rlist;
+}
 
-                default: /* backwards */
+/** @param start Range start.
+ *  @param end Range end.
+ *  @return regions which have some part within this range.
+ */
+boost::shared_ptr<RegionList>
+Playlist::regions_touched (framepos_t start, framepos_t end)
+{
+       RegionReadLock rlock (this);
+       return regions_touched_locked (start, end);
+}
 
-                        if (pos < frame) {
-                                if ((distance = frame - pos) < closest) {
-                                        closest = distance;
-                                        ret = r;
-                                }
-                        }
-                        else {
-                                end_iter = true;
-                        }
+boost::shared_ptr<RegionList>
+Playlist::regions_touched_locked (framepos_t start, framepos_t end)
+{
+       boost::shared_ptr<RegionList> rlist (new RegionList);
+       
+       for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
+               if ((*i)->coverage (start, end) != Evoral::OverlapNone) {
+                       rlist->push_back (*i);
+               }
+       }
+       
+       return rlist;
+}
 
-                        break;
-                }
-        }
+framepos_t
+Playlist::find_next_transient (framepos_t from, int dir)
+{
+       RegionReadLock rlock (this);
+       AnalysisFeatureList points;
+       AnalysisFeatureList these_points;
+       
+       for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
+               if (dir > 0) {
+                       if ((*i)->last_frame() < from) {
+                               continue;
+                       }
+               } else {
+                       if ((*i)->first_frame() > from) {
+                               continue;
+                       }
+               }
+               
+               (*i)->get_transients (these_points);
+               
+               /* add first frame, just, err, because */
+               
+               these_points.push_back ((*i)->first_frame());
+               
+               points.insert (points.end(), these_points.begin(), these_points.end());
+               these_points.clear ();
+       }
+       
+       if (points.empty()) {
+               return -1;
+       }
+       
+       TransientDetector::cleanup_transients (points, _session.frame_rate(), 3.0);
+       bool reached = false;
+       
+       if (dir > 0) {
+               for (AnalysisFeatureList::iterator x = points.begin(); x != points.end(); ++x) {
+                       if ((*x) >= from) {
+                               reached = true;
+                       }
+                       
+                       if (reached && (*x) > from) {
+                               return *x;
+                       }
+               }
+       } else {
+               for (AnalysisFeatureList::reverse_iterator x = points.rbegin(); x != points.rend(); ++x) {
+                       if ((*x) <= from) {
+                               reached = true;
+                       }
+                       
+                       if (reached && (*x) < from) {
+                               return *x;
+                       }
+               }
+       }
+       
+       return -1;
+}
 
-        return ret;
- }
+boost::shared_ptr<Region>
+Playlist::find_next_region (framepos_t frame, RegionPoint point, int dir)
+{
+       RegionReadLock rlock (this);
+       boost::shared_ptr<Region> ret;
+       framepos_t closest = max_framepos;
+       
+       bool end_iter = false;
+       
+       for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
+               
+               if(end_iter) break;
+               
+               frameoffset_t distance;
+               boost::shared_ptr<Region> r = (*i);
+               framepos_t pos = 0;
+               
+               switch (point) {
+               case Start:
+                       pos = r->first_frame ();
+                       break;
+               case End:
+                       pos = r->last_frame ();
+                       break;
+               case SyncPoint:
+                       pos = r->sync_position ();
+                       break;
+               }
+               
+               switch (dir) {
+               case 1: /* forwards */
+                       
+                       if (pos > frame) {
+                               if ((distance = pos - frame) < closest) {
+                                       closest = distance;
+                                       ret = r;
+                                       end_iter = true;
+                               }
+                       }
+                       
+                       break;
+                       
+               default: /* backwards */
+                       
+                       if (pos < frame) {
+                               if ((distance = frame - pos) < closest) {
+                                       closest = distance;
+                                       ret = r;
+                               }
+                       } else {
+                               end_iter = true;
+                       }
+                       
+                       break;
+               }
+       }
+       
+       return ret;
+}
 
  framepos_t
  Playlist::find_next_region_boundary (framepos_t frame, int dir)
  {
-        RegionLock rlock (this);
+        RegionReadLock rlock (this);
 
         framepos_t closest = max_framepos;
         framepos_t ret = -1;
@@ -2078,14 +2041,14 @@ Playlist::flush_notifications (bool from_undo)
  void
  Playlist::rdiff (vector<Command*>& cmds) const
  {
-        RegionLock rlock (const_cast<Playlist *> (this));
+        RegionReadLock rlock (const_cast<Playlist *> (this));
         Stateful::rdiff (cmds);
  }
 
  void
  Playlist::clear_owned_changes ()
  {
-        RegionLock rlock (this);
+        RegionReadLock rlock (this);
         Stateful::clear_owned_changes ();
  }
 
@@ -2097,11 +2060,11 @@ Playlist::flush_notifications (bool from_undo)
 
         freeze ();
         /* add the added regions */
-        for (RegionListProperty::ChangeContainer::iterator i = change.added.begin(); i != change.added.end(); ++i) {
-                add_region ((*i), (*i)->position());
+        for (RegionListProperty::ChangeContainer::const_iterator i = change.added.begin(); i != change.added.end(); ++i) {
+                add_region_internal ((*i), (*i)->position());
         }
         /* remove the removed regions */
-        for (RegionListProperty::ChangeContainer::iterator i = change.removed.begin(); i != change.removed.end(); ++i) {
+        for (RegionListProperty::ChangeContainer::const_iterator i = change.removed.begin(); i != change.removed.end(); ++i) {
                 remove_region (*i);
         }
 
@@ -2129,7 +2092,6 @@ Playlist::flush_notifications (bool from_undo)
                 return -1;
         }
 
-        suspend_relayer ();
         freeze ();
 
         plist = node.properties();
@@ -2190,8 +2152,11 @@ Playlist::flush_notifications (bool from_undo)
                                return -1;
                        }
 
-                       add_region (region, region->position(), 1.0);
-
+                        {
+                                RegionWriteLock rlock (this);
+                                add_region_internal (region, region->position());
+                        }
+                       
                        region->resume_property_changes ();
 
                }
@@ -2199,23 +2164,14 @@ Playlist::flush_notifications (bool from_undo)
 
        if (seen_region_nodes && regions.empty()) {
                ret = -1;
-       } else {
-
-               /* update dependents, which was not done during add_region_internal
-                  due to in_set_state being true
-               */
-               
-               for (RegionList::iterator r = regions.begin(); r != regions.end(); ++r) {
-                       check_dependents (*r, false);
-               }
        }
                
        thaw ();
        notify_contents_changed ();
-       resume_relayer ();
 
        in_set_state--;
        first_set_state = false;
+
        return ret;
 }
 
@@ -2248,7 +2204,7 @@ Playlist::state (bool full_state)
        node->add_property (X_("frozen"), _frozen ? "yes" : "no");
 
        if (full_state) {
-               RegionLock rlock (this, false);
+               RegionReadLock rlock (this);
 
                snprintf (buf, sizeof (buf), "%u", _combine_ops);
                node->add_property ("combine-ops", buf);
@@ -2268,24 +2224,42 @@ Playlist::state (bool full_state)
 bool
 Playlist::empty() const
 {
-       RegionLock rlock (const_cast<Playlist *>(this), false);
+       RegionReadLock rlock (const_cast<Playlist *>(this));
        return regions.empty();
 }
 
 uint32_t
 Playlist::n_regions() const
 {
-       RegionLock rlock (const_cast<Playlist *>(this), false);
+       RegionReadLock rlock (const_cast<Playlist *>(this));
        return regions.size();
 }
 
+/** @return true if the all_regions list is empty, ie this playlist
+ *  has never had a region added to it.
+ */
+bool
+Playlist::all_regions_empty() const
+{
+       RegionReadLock rl (const_cast<Playlist *> (this));
+       return all_regions.empty();
+}
+
 pair<framepos_t, framepos_t>
 Playlist::get_extent () const
 {
-       RegionLock rlock (const_cast<Playlist *>(this), false);
+       RegionReadLock rlock (const_cast<Playlist *>(this));
        return _get_extent ();
 }
 
+pair<framepos_t, framepos_t>
+Playlist::get_extent_with_endspace () const
+{
+       pair<framepos_t, framepos_t> l = get_extent();
+       l.second += _end_space;
+       return l;
+}
+
 pair<framepos_t, framepos_t>
 Playlist::_get_extent () const
 {
@@ -2325,7 +2299,7 @@ Playlist::bump_name (string name, Session &session)
 layer_t
 Playlist::top_layer() const
 {
-       RegionLock rlock (const_cast<Playlist *> (this));
+       RegionReadLock rlock (const_cast<Playlist *> (this));
        layer_t top = 0;
 
        for (RegionList::const_iterator i = regions.begin(); i != regions.end(); ++i) {
@@ -2340,264 +2314,197 @@ Playlist::set_edit_mode (EditMode mode)
        _edit_mode = mode;
 }
 
-/** Relayer a region.  See the other relayer() methods for commentary. */
+struct RelayerSort {
+       bool operator () (boost::shared_ptr<Region> a, boost::shared_ptr<Region> b) {
+               return a->layering_index() < b->layering_index();
+       }
+};
+
+/** Set a new layer for a region.  This adjusts the layering indices of all
+ *  regions in the playlist to put the specified region in the appropriate
+ *  place.  The actual layering will be fixed up when relayer() happens.
+ */
+
 void
-Playlist::relayer (boost::shared_ptr<Region> region)
+Playlist::set_layer (boost::shared_ptr<Region> region, double new_layer)
 {
-       if (_relayer_suspended) {
-               return;
+       /* Remove the layer we are setting from our region list, and sort it */
+       RegionList copy = regions.rlist();
+       copy.remove (region);
+       copy.sort (RelayerSort ());
+
+       /* Put region back in the right place */
+       RegionList::iterator i = copy.begin();
+       while (i != copy.end ()) {
+               if ((*i)->layer() > new_layer) {
+                       break;
+               }
+               ++i;
        }
        
-       RegionList r;
-       r.push_back (region);
-       relayer (r);
+       copy.insert (i, region);
+
+       setup_layering_indices (copy);
 }
 
-Playlist::TemporaryLayers
-Playlist::compute_temporary_layers (RegionList const & relayer_regions)
+void
+Playlist::setup_layering_indices (RegionList const & regions)
 {
-       TemporaryLayers temporary_layers;
-       OverlapCache cache (this);
+       uint64_t j = 0;
+       list<Evoral::Range<framepos_t> > xf;
 
-       for (RegionList::const_iterator i = relayer_regions.begin(); i != relayer_regions.end(); ++i) {
+       for (RegionList::const_iterator k = regions.begin(); k != regions.end(); ++k) {
+               (*k)->set_layering_index (j++);
+       }
+}
 
-               DEBUG_TRACE (DEBUG::Layering, string_compose ("Compute temporary layer for %1\n", (*i)->name()));
-       
-               /* current_overlaps: regions that overlap *i now */
-               RegionList current_overlaps = cache.get ((*i)->bounds ());
-               current_overlaps.remove (*i);
+/** Take the layering indices of each of our regions, compute the layers
+ *  that they should be on, and write the layers back to the regions.
+ */
+void
+Playlist::relayer ()
+{
+       /* never compute layers when setting from XML */
 
-               DEBUG_TRACE (DEBUG::Layering, "Current overlaps:\n");
-               for (RegionList::iterator j = current_overlaps.begin(); j != current_overlaps.end(); ++j) {
-                       DEBUG_TRACE (DEBUG::Layering, string_compose ("\t%1\n", (*j)->name()));
-               }
-               
-               /* overlaps_to_preserve: regions that overlap *i now, but which aren't being
-                  worked on during this relayer: these will have their relationship with
-                  *i preserved.
-               */
-               RegionList overlaps_to_preserve;
+       if (in_set_state) {
+               return;
+       }
 
-               /* overlaps_to_check: regions that overlap *i now, and must be checked to
-                  see if *i is still on the correct layer with respect to them (according
-                  to current layering rules).
-               */
-               RegionList overlaps_to_check;
+       /* Build up a new list of regions on each layer, stored in a set of lists
+          each of which represent some period of time on some layer.  The idea
+          is to avoid having to search the entire region list to establish whether
+          each region overlaps another */
 
-               if (_session.config.get_relayer_on_all_edits () || (*i)->last_layer_op (LayerOpAdd) > (*i)->last_layer_op (LayerOpBoundsChange)) {
-                       /* We're configured to relayer on all edits, or this region has had
-                          no edit since it was added to the playlist, so we're relayering
-                          the whole lot; in this case there are no `overlaps_to_preserve'.
-                       */
-                       overlaps_to_check = current_overlaps;
-               } else {
-                       /* We're only relayering new overlaps; find them */
-                       RegionList last_overlaps = cache.get ((*i)->last_relayer_bounds ());
-                       last_overlaps.remove (*i);
-                       for (RegionList::const_iterator j = current_overlaps.begin(); j != current_overlaps.end(); ++j) {
-                               if (find (last_overlaps.begin(), last_overlaps.end(), *j) == last_overlaps.end()) {
-                                       /* This is a new overlap, which must be checked */
-                                       overlaps_to_check.push_back (*j);
-                               } else {
-                                       /* This is an existing overlap, which must be preserved */
-                                       overlaps_to_preserve.push_back (*j);
-                               }
-                       }
-               }
+       /* how many pieces to divide this playlist's time up into */
+       int const divisions = 512;
 
-               if (overlaps_to_check.empty ()) {
-                       /* There are no overlaps to check, so just leave everything as it is */
-                       continue;
-               }
+       /* find the start and end positions of the regions on this playlist */
+       framepos_t start = INT64_MAX;
+       framepos_t end = 0;
+       for (RegionList::const_iterator i = regions.begin(); i != regions.end(); ++i) {
+               start = min (start, (*i)->position());
+               end = max (end, (*i)->position() + (*i)->length());
+       }
 
-               /* Put *i on our overlaps_to_check_list */
-               overlaps_to_check.push_back (*i);
+       /* hence the size of each time division */
+       double const division_size = (end - start) / double (divisions);
 
-               /* And sort it according to the current layer model */
-               switch (_session.config.get_layer_model()) {
-               case LaterHigher:
-                       overlaps_to_check.sort (RegionSortByPosition ());
-                       break;
-               case AddOrBoundsChangeHigher:
-                       overlaps_to_check.sort (RegionSortByAddOrBounds ());
-                       break;
-               case AddHigher:
-                       overlaps_to_check.sort (RegionSortByAdd ());
-                       break;
-               }
+       vector<vector<RegionList> > layers;
+       layers.push_back (vector<RegionList> (divisions));
 
-               /* Now find *i in our overlaps_to_check list; within this list it will be in the
-                  right place wrt the current layering rules, so we can work out the layers of the
-                  nearest regions below and above.
-               */
-               double previous_layer = -DBL_MAX;
-               double next_layer = DBL_MAX;
-               RegionList::const_iterator j = overlaps_to_check.begin();
-               while (*j != *i) {
-                       previous_layer = temporary_layers.get (*j);
-                       ++j;
-               }
+       /* Sort our regions into layering index order */
+       RegionList copy = regions.rlist();
+       copy.sort (RelayerSort ());
 
-               /* we must have found *i */
-               assert (j != overlaps_to_check.end ());
+       DEBUG_TRACE (DEBUG::Layering, "relayer() using:\n");
+       for (RegionList::iterator i = copy.begin(); i != copy.end(); ++i) {
+               DEBUG_TRACE (DEBUG::Layering, string_compose ("\t%1 %2\n", (*i)->name(), (*i)->layering_index()));
+       }
 
-               ++j;
-               if (j != overlaps_to_check.end ()) {
-                       next_layer = temporary_layers.get (*j);
-               }
+       for (RegionList::iterator i = copy.begin(); i != copy.end(); ++i) {
 
-               /* Now we know where *i and overlaps_to_preserve should go: between previous_layer and
-                  next_layer.
+               /* find the time divisions that this region covers; if there are no regions on the list,
+                  division_size will equal 0 and in this case we'll just say that
+                  start_division = end_division = 0.
                */
-
-               /* Recurse into overlaps_to_preserve to find dependents */
-               RegionList recursed_overlaps_to_preserve;
-               
-               for (RegionList::const_iterator k = overlaps_to_preserve.begin(); k != overlaps_to_preserve.end(); ++k) {
-                       recursed_overlaps_to_preserve.push_back (*k);
-                       RegionList touched = recursive_regions_touched (*k, cache, *i);
-                       for (RegionList::iterator m = touched.begin(); m != touched.end(); ++m) {
-                               if (find (recursed_overlaps_to_preserve.begin(), recursed_overlaps_to_preserve.end(), *m) == recursed_overlaps_to_preserve.end()) {
-                                       recursed_overlaps_to_preserve.push_back (*m);
-                               }
+               int start_division = 0;
+               int end_division = 0;
+
+               if (division_size > 0) {
+                       start_division = floor ( ((*i)->position() - start) / division_size);
+                       end_division = floor ( ((*i)->position() + (*i)->length() - start) / division_size );
+                       if (end_division == divisions) {
+                               end_division--;
                        }
                }
 
-               /* Put *i into the overlaps_to_preserve list */
-               recursed_overlaps_to_preserve.push_back (*i);
-
-               /* Sort it by layer, so that we preserve layering */
-               recursed_overlaps_to_preserve.sort (SortByTemporaryLayer (temporary_layers));
-
-               /* Divide available space up into chunks so that we can relayer everything in that space */
-               double const space = (next_layer - previous_layer) / (recursed_overlaps_to_preserve.size() + 1);
-
-               /* And relayer */
-               int m = 1;
-               for (RegionList::const_iterator k = recursed_overlaps_to_preserve.begin(); k != recursed_overlaps_to_preserve.end(); ++k) {
-                       temporary_layers.set (*k, previous_layer + space * m);
-                       ++m;
-               }
-       }
-
-       return temporary_layers;
-}
+               assert (divisions == 0 || end_division < divisions);
 
-/** Take a list of temporary layer indices and set up the layers of all regions
- *  based on them.
- */
-void
-Playlist::commit_temporary_layers (TemporaryLayers const & temporary_layers)
-{
-       /* Sort all the playlist's regions by layer, ascending */
-       RegionList all_regions = regions.rlist ();
-       all_regions.sort (SortByTemporaryLayer (temporary_layers));
+               /* find the lowest layer that this region can go on */
+               size_t j = layers.size();
+               while (j > 0) {
+                       /* try layer j - 1; it can go on if it overlaps no other region
+                          that is already on that layer
+                       */
 
-       DEBUG_TRACE (DEBUG::Layering, "Commit layering:\n");
+                       bool overlap = false;
+                       for (int k = start_division; k <= end_division; ++k) {
+                               RegionList::iterator l = layers[j-1][k].begin ();
+                               while (l != layers[j-1][k].end()) {
+                                       if ((*l)->overlap_equivalent (*i)) {
+                                               overlap = true;
+                                               break;
+                                       }
+                                       l++;
+                               }
 
-       for (RegionList::iterator i = all_regions.begin(); i != all_regions.end(); ++i) {
+                               if (overlap) {
+                                       break;
+                               }
+                       }
 
-               /* Go through the regions that we have already layered and hence work
-                  out the maximum layer index that is in used at some point during
-                  region *i.
-               */
-               
-               layer_t max_layer_here = 0;
-               bool have_overlap = false;
-               for (RegionList::iterator j = all_regions.begin(); j != i; ++j) {
-                       if ((*j)->overlap_equivalent (*i)) {
-                               max_layer_here = max ((*j)->layer (), max_layer_here);
-                               have_overlap = true;
+                       if (overlap) {
+                               /* overlap, so we must use layer j */
+                               break;
                        }
-               }
 
-               if (have_overlap) {
-                       /* *i overlaps something, so put it on the next available layer */
-                       (*i)->set_layer (max_layer_here + 1);
-               } else {
-                       /* no overlap, so put on the bottom layer */
-                       (*i)->set_layer (0);
+                       --j;
                }
-               
-               DEBUG_TRACE (DEBUG::Layering, string_compose ("\t%1 %2\n", (*i)->name(), (*i)->layer()));
-       }
 
-       notify_layering_changed ();
-}
+               if (j == layers.size()) {
+                       /* we need a new layer for this region */
+                       layers.push_back (vector<RegionList> (divisions));
+               }
 
-/** Relayer a list of regions.
- *
- *  Taking each region R in turn, this method examines the regions O that overlap R in time.
- *  If the session configuration option "relayer-on-all-moves" is false, we reduce O so that
- *  it contains only those regions with which new overlaps have been formed since the last
- *  relayer.
- *
- *  We then change the layer of R and its indirect overlaps so that R meets the current
- *  Session layer model with respect to O.  See doc/layering.
- */
+               /* put a reference to this region in each of the divisions that it exists in */
+               for (int k = start_division; k <= end_division; ++k) {
+                       layers[j][k].push_back (*i);
+               }
 
-void
-Playlist::relayer (RegionList const & relayer_regions)
-{
-       if (_relayer_suspended) {
-               return;
+               (*i)->set_layer (j);
        }
 
-       /* We do this in two parts: first; compute `temporary layer' indices for
-          regions on the playlist.  These are (possibly) fractional indices, which
-          are a convenient means of working with things when you want to insert layers
-          between others.
+       /* It's a little tricky to know when we could avoid calling this; e.g. if we are
+          relayering because we just removed the only region on the top layer, nothing will
+          appear to have changed, but the StreamView must still sort itself out.  We could
+          probably keep a note of the top layer last time we relayered, and check that,
+          but premature optimisation &c...
        */
+       notify_layering_changed ();
 
-       TemporaryLayers temporary_layers = compute_temporary_layers (relayer_regions);
-
-       /* Second, we fix up these temporary layers and `commit' them by writing
-          them to the regions involved.
+       /* This relayer() may have been called as a result of a region removal, in which
+          case we need to setup layering indices to account for the one that has just
+          gone away.
        */
-       
-       commit_temporary_layers (temporary_layers);
-}
-
-/** Put a region on some fractional layer and sort everything else out around it.
- *  This can be used to force a region into some layering; for example, calling
- *  this method with temporary_layer == -0.5 will put the region at the bottom of
- *  the stack.
- */
-
-void
-Playlist::relayer (boost::shared_ptr<Region> region, double temporary_layer)
-{
-       if (_relayer_suspended) {
-               return;
-       }
-
-       TemporaryLayers t;
-       t.set (region, temporary_layer);
-       commit_temporary_layers (t);
+       setup_layering_indices (copy);
 }
 
 void
 Playlist::raise_region (boost::shared_ptr<Region> region)
 {
-       relayer (region, region->layer() + 0.5);
+       set_layer (region, region->layer() + 1.5);
+       relayer ();
 }
 
 void
 Playlist::lower_region (boost::shared_ptr<Region> region)
 {
-       relayer (region, region->layer() - 0.5);
+       set_layer (region, region->layer() - 1.5);
+       relayer ();
 }
 
 void
 Playlist::raise_region_to_top (boost::shared_ptr<Region> region)
 {
-       relayer (region, max_layer);
+       set_layer (region, DBL_MAX);
+       relayer ();
 }
 
 void
 Playlist::lower_region_to_bottom (boost::shared_ptr<Region> region)
 {
-       relayer (region, -0.5);
+       set_layer (region, -0.5);
+       relayer ();
 }
 
 void
@@ -2609,7 +2516,7 @@ Playlist::nudge_after (framepos_t start, framecnt_t distance, bool forwards)
        _nudging = true;
 
        {
-               RegionLock rlock (const_cast<Playlist *> (this));
+               RegionWriteLock rlock (const_cast<Playlist *> (this));
 
                for (i = regions.begin(); i != regions.end(); ++i) {
 
@@ -2650,9 +2557,9 @@ Playlist::nudge_after (framepos_t start, framecnt_t distance, bool forwards)
 bool
 Playlist::uses_source (boost::shared_ptr<const Source> src) const
 {
-       RegionLock rlock (const_cast<Playlist*> (this));
+       RegionReadLock rlock (const_cast<Playlist*> (this));
 
-       for (set<boost::shared_ptr<Region> >::iterator r = all_regions.begin(); r != all_regions.end(); ++r) {
+       for (set<boost::shared_ptr<Region> >::const_iterator r = all_regions.begin(); r != all_regions.end(); ++r) {
                if ((*r)->uses_source (src)) {
                        return true;
                }
@@ -2664,7 +2571,7 @@ Playlist::uses_source (boost::shared_ptr<const Source> src) const
 boost::shared_ptr<Region>
 Playlist::find_region (const ID& id) const
 {
-       RegionLock rlock (const_cast<Playlist*> (this));
+       RegionReadLock rlock (const_cast<Playlist*> (this));
 
        /* searches all regions currently in use by the playlist */
 
@@ -2680,7 +2587,7 @@ Playlist::find_region (const ID& id) const
 uint32_t
 Playlist::region_use_count (boost::shared_ptr<Region> r) const
 {
-       RegionLock rlock (const_cast<Playlist*> (this));
+       RegionReadLock rlock (const_cast<Playlist*> (this));
        uint32_t cnt = 0;
 
        for (RegionList::const_iterator i = regions.begin(); i != regions.end(); ++i) {
@@ -2697,7 +2604,7 @@ Playlist::region_by_id (const ID& id) const
 {
        /* searches all regions ever added to this playlist */
 
-       for (set<boost::shared_ptr<Region> >::iterator i = all_regions.begin(); i != all_regions.end(); ++i) {
+       for (set<boost::shared_ptr<Region> >::const_iterator i = all_regions.begin(); i != all_regions.end(); ++i) {
                if ((*i)->id() == id) {
                        return *i;
                }
@@ -2732,24 +2639,9 @@ Playlist::set_frozen (bool yn)
        _frozen = yn;
 }
 
-void
-Playlist::timestamp_layer_op (LayerOp op, boost::shared_ptr<Region> region)
-{
-       region->set_last_layer_op (op, ++layer_op_counter);
-}
-
-
-/** Find the next or previous region after `region' (next if dir > 0, previous otherwise)
- *  and swap its position with `region'.
- */
 void
 Playlist::shuffle (boost::shared_ptr<Region> region, int dir)
 {
-       /* As regards layering, the calls we make to set_position() will
-          perform layering as if the regions had been moved, which I think
-          is about right.
-       */
-       
        bool moved = false;
 
        if (region->locked()) {
@@ -2759,7 +2651,7 @@ Playlist::shuffle (boost::shared_ptr<Region> region, int dir)
        _shuffling = true;
 
        {
-               RegionLock rlock (const_cast<Playlist*> (this));
+               RegionWriteLock rlock (const_cast<Playlist*> (this));
 
 
                if (dir > 0) {
@@ -2854,15 +2746,17 @@ Playlist::shuffle (boost::shared_ptr<Region> region, int dir)
        _shuffling = false;
 
        if (moved) {
-               check_dependents (region, false);
+
+               relayer ();
                notify_contents_changed();
        }
+
 }
 
 bool
 Playlist::region_is_shuffle_constrained (boost::shared_ptr<Region>)
 {
-       RegionLock rlock (const_cast<Playlist*> (this));
+       RegionReadLock rlock (const_cast<Playlist*> (this));
 
        if (regions.size() > 1) {
                return true;
@@ -2871,10 +2765,16 @@ Playlist::region_is_shuffle_constrained (boost::shared_ptr<Region>)
        return false;
 }
 
+void
+Playlist::ripple (framepos_t at, framecnt_t distance, RegionList *exclude)
+{
+       ripple_locked (at, distance, exclude);
+}
+
 void
 Playlist::update_after_tempo_map_change ()
 {
-       RegionLock rlock (const_cast<Playlist*> (this));
+       RegionWriteLock rlock (const_cast<Playlist*> (this));
        RegionList copy (regions.rlist());
 
        freeze ();
@@ -2889,7 +2789,7 @@ Playlist::update_after_tempo_map_change ()
 void
 Playlist::foreach_region (boost::function<void(boost::shared_ptr<Region>)> s)
 {
-       RegionLock rl (this, false);
+       RegionWriteLock rl (this, false);
        for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
                s (*i);
        }
@@ -2898,7 +2798,7 @@ Playlist::foreach_region (boost::function<void(boost::shared_ptr<Region>)> s)
 bool
 Playlist::has_region_at (framepos_t const p) const
 {
-       RegionLock (const_cast<Playlist *> (this));
+       RegionReadLock (const_cast<Playlist *> (this));
 
        RegionList::const_iterator i = regions.begin ();
        while (i != regions.end() && !(*i)->covers (p)) {
@@ -2912,7 +2812,7 @@ Playlist::has_region_at (framepos_t const p) const
 void
 Playlist::remove_region_by_source (boost::shared_ptr<Source> s)
 {
-       RegionLock rl (this);
+       RegionWriteLock rl (this);
 
        RegionList::iterator i = regions.begin();
        while (i != regions.end()) {
@@ -2935,7 +2835,7 @@ Playlist::remove_region_by_source (boost::shared_ptr<Source> s)
 framepos_t
 Playlist::find_next_top_layer_position (framepos_t t) const
 {
-       RegionLock rlock (const_cast<Playlist *> (this));
+       RegionReadLock rlock (const_cast<Playlist *> (this));
 
        layer_t const top = top_layer ();
 
@@ -2986,7 +2886,14 @@ Playlist::combine (const RegionList& r)
 
        pl->in_partition = true;
 
-       for (RegionList::const_iterator i = r.begin(); i != r.end(); ++i) {
+       /* sort by position then layer.
+        * route_time_axis passes 'selected_regions' - which is not sorted.
+        * here we need the top-most first, then every layer's region sorted by position.
+        */
+       RegionList sorted(r);
+       sorted.sort(RegionSortByLayerAndPosition());
+
+       for (RegionList::const_iterator i = sorted.begin(); i != sorted.end(); ++i) {
 
                /* copy the region */
 
@@ -3002,6 +2909,7 @@ Playlist::combine (const RegionList& r)
                /* make position relative to zero */
 
                pl->add_region (copied_region, original_region->position() - earliest_position);
+               copied_region->set_layer (original_region->layer ());
 
                /* use the maximum number of channels for any region */
 
@@ -3016,10 +2924,6 @@ Playlist::combine (const RegionList& r)
 
        pre_combine (copies);
 
-       /* add any dependent regions to the new playlist */
-
-       copy_dependents (old_and_new_regions, pl.get());
-
        /* now create a new PlaylistSource for each channel in the new playlist */
 
        SourceList sources;
@@ -3134,6 +3038,7 @@ Playlist::uncombine (boost::shared_ptr<Region> target)
                }
 
                boost::shared_ptr<Region> original (ca->second);
+               cassocs.erase(ca);
                bool modified_region;
 
                if (i == rl.begin()) {
@@ -3161,13 +3066,13 @@ Playlist::uncombine (boost::shared_ptr<Region> target)
                modified_region = false;
 
                switch (original->coverage (adjusted_start, adjusted_end)) {
-               case OverlapNone:
+               case Evoral::OverlapNone:
                        /* original region does not cover any part
                           of the current state of the compound region
                        */
                        continue;
 
-               case OverlapInternal:
+               case Evoral::OverlapInternal:
                        /* overlap is just a small piece inside the
                         * original so trim both ends
                         */
@@ -3175,13 +3080,13 @@ Playlist::uncombine (boost::shared_ptr<Region> target)
                        modified_region = true;
                        break;
 
-               case OverlapExternal:
+               case Evoral::OverlapExternal:
                        /* overlap fully covers original, so leave it
                           as is
                        */
                        break;
 
-               case OverlapEnd:
+               case Evoral::OverlapEnd:
                        /* overlap starts within but covers end,
                           so trim the front of the region
                        */
@@ -3189,7 +3094,7 @@ Playlist::uncombine (boost::shared_ptr<Region> target)
                        modified_region = true;
                        break;
 
-               case OverlapStart:
+               case Evoral::OverlapStart:
                        /* overlap covers start but ends within, so
                         * trim the end of the region.
                         */
@@ -3230,20 +3135,30 @@ Playlist::uncombine (boost::shared_ptr<Region> target)
 
        for (vector<boost::shared_ptr<Region> >::iterator i = originals.begin(); i != originals.end(); ++i) {
                add_region ((*i), (*i)->position());
+               set_layer((*i), (*i)->layer());
+               if (!RegionFactory::region_by_id((*i)->id())) {
+                       RegionFactory::map_add(*i);
+               }
        }
 
-       /* now move dependent regions back from the compound to this playlist */
-
-       pl->copy_dependents (old_and_new_regions, this);
-
        in_partition = false;
        thaw ();
 }
 
+void
+Playlist::fade_range (list<AudioRange>& ranges)
+{
+        for (list<AudioRange>::iterator r = ranges.begin(); r != ranges.end(); ++r) {
+                for (RegionList::const_iterator i = regions.begin(); i != regions.end(); ++i) {
+                        (*i)->fade_range ((*r).start, (*r).end);
+                }
+        }
+}
+
 uint32_t
 Playlist::max_source_level () const
 {
-       RegionLock rlock (const_cast<Playlist *> (this));
+       RegionReadLock rlock (const_cast<Playlist *> (this));
        uint32_t lvl = 0;
 
        for (RegionList::const_iterator i = regions.begin(); i != regions.end(); ++i) {
@@ -3253,167 +3168,44 @@ Playlist::max_source_level () const
        return lvl;
 }
 
-
-uint32_t
-Playlist::count_joined_regions () const
-{
-       RegionLock rlock (const_cast<Playlist *> (this));
-       uint32_t cnt = 0;
-
-       for (RegionList::const_iterator i = regions.begin(); i != regions.end(); ++i) {
-               if ((*i)->max_source_level() > 0) {
-                       cnt++;
-               }
-       }
-
-       return cnt;
-}
-
 void
 Playlist::set_orig_track_id (const PBD::ID& id)
 {
        _orig_track_id = id;
 }
 
-/** Set the temporary layer for a region */
-void
-Playlist::TemporaryLayers::set (boost::shared_ptr<Region> r, double l)
-{
-       _map[r] = l;
-}
-
-/** Return the temporary layer for a region, if one has been specified
- *  to this TemporaryLayers object; if not return the region's current
- *  layer.
- */
-double
-Playlist::TemporaryLayers::get (boost::shared_ptr<Region> r) const
-{
-       Map::const_iterator i = _map.find (r);
-       if (i != _map.end ()) {
-               return i->second;
-       }
-
-       return double (r->layer ());
-}
-
-int const Playlist::OverlapCache::_divisions = 512;
-
-/** Set up an OverlapCache for a playlist; the cache will only be valid until
- *  the Playlist is changed.
+/** Take a list of ranges, coalesce any that can be coalesced, then call
+ *  check_crossfades for each one.
  */
-Playlist::OverlapCache::OverlapCache (Playlist* playlist)
-       : _range (0, 0)
-{
-       /* Find the start and end positions of the regions on this playlist */
-       _range = Evoral::Range<framepos_t> (max_framepos, 0);
-       RegionList const & rl = playlist->region_list().rlist ();
-       for (RegionList::const_iterator i = rl.begin(); i != rl.end(); ++i) {
-               Evoral::Range<framepos_t> const b = (*i)->bounds ();
-               _range.from = min (_range.from, b.from);
-               _range.to = max (_range.to, b.to);
-       }
-
-       /* Hence the size of each time divison */
-       _division_size = (_range.to - _range.from) / double (_divisions);
-
-       _cache.resize (_divisions);
-
-       /* Build the cache */
-       for (RegionList::const_iterator i = rl.begin(); i != rl.end(); ++i) {
-               pair<int, int> ind = cache_indices ((*i)->bounds ());
-               for (int j = ind.first; j < ind.second; ++j) {
-                       _cache[j].push_back (*i);
-               }
-       }
-}
-
-/** @param range Range, in frames.
- *  @return From and to cache indices for  (to is exclusive).
- */
-pair<int, int>
-Playlist::OverlapCache::cache_indices (Evoral::Range<framepos_t> range) const
+void
+Playlist::coalesce_and_check_crossfades (list<Evoral::Range<framepos_t> > ranges)
 {
-       range.from = max (range.from, _range.from);
-       range.to = min (range.to, _range.to);
-       
-       pair<int, int> const p = make_pair (
-               floor ((range.from - _range.from) / _division_size),
-               ceil ((range.to - _range.from) / _division_size)
-               );
+       /* XXX: it's a shame that this coalesce algorithm also exists in
+          TimeSelection::consolidate().
+       */
 
-       assert (p.first >= 0);
-       assert (p.second <= _divisions);
+       /* XXX: xfade: this is implemented in Evoral::RangeList */
 
-       return p;
-}
+restart:
+       for (list<Evoral::Range<framepos_t> >::iterator i = ranges.begin(); i != ranges.end(); ++i) {
+               for (list<Evoral::Range<framepos_t> >::iterator j = ranges.begin(); j != ranges.end(); ++j) {
 
-/** Return the regions that overlap a given range.  The returned list
- *  is not guaranteed to be in the same order as the Playlist that it was
- *  generated from.
- */
-Playlist::RegionList
-Playlist::OverlapCache::get (Evoral::Range<framepos_t> range) const
-{
-       if (_range.from == max_framepos) {
-               return RegionList ();
-       }
-       
-       RegionList r;
+                       if (i == j) {
+                               continue;
+                       }
 
-       pair<int, int> ind = cache_indices (range);
-       for (int i = ind.first; i < ind.second; ++i) {
-               for (RegionList::const_iterator j = _cache[i].begin(); j != _cache[i].end(); ++j) {
-                       if ((*j)->coverage (range.from, range.to) != OverlapNone) {
-                               r.push_back (*j);
+                       if (Evoral::coverage (i->from, i->to, j->from, j->to) != Evoral::OverlapNone) {
+                               i->from = min (i->from, j->from);
+                               i->to = max (i->to, j->to);
+                               ranges.erase (j);
+                               goto restart;
                        }
                }
        }
-
-       r.sort ();
-       r.unique ();
-
-       return r;
 }
 
 void
-Playlist::suspend_relayer ()
+Playlist::set_capture_insertion_in_progress (bool yn)
 {
-       _relayer_suspended = true;
+       _capture_insertion_underway = yn;
 }
-
-void
-Playlist::resume_relayer ()
-{
-       _relayer_suspended = false;
-}
-
-/** Examine a region and return regions which overlap it, and also those which overlap those which overlap etc.
- *  @param ignore Optional region which should be treated as if it doesn't exist (ie not returned in the list,
- *  and not recursed into).
- */
-Playlist::RegionList
-Playlist::recursive_regions_touched (boost::shared_ptr<Region> region, OverlapCache const & cache, boost::shared_ptr<Region> ignore) const
-{
-       RegionList touched;
-       recursive_regions_touched_sub (region, cache, ignore, touched);
-
-       touched.remove (region);
-       return touched;
-}
-
-/** Recursive sub-routine of recursive_regions_touched */
-void
-Playlist::recursive_regions_touched_sub (
-       boost::shared_ptr<Region> region, OverlapCache const & cache, boost::shared_ptr<Region> ignore, RegionList & touched
-       ) const
-{
-       RegionList r = cache.get (region->bounds ());
-       for (RegionList::iterator i = r.begin(); i != r.end(); ++i) {
-               if (find (touched.begin(), touched.end(), *i) == touched.end() && *i != ignore) {
-                       touched.push_back (*i);
-                       recursive_regions_touched_sub (*i, cache, ignore, touched);
-               }
-       }
-}
-