cleanup up cleanup at session destruction; clarify the meaning of 3 signals (DropRefe...
[ardour.git] / libs / ardour / audio_diskstream.cc
index 48f3771019501c4f6822de6fa0665e4d840b6e6e..fb225671e9ba8198ea1a8bb557803c2946d0a7c8 100644 (file)
@@ -1,5 +1,5 @@
 /*
-    Copyright (C) 2000-2006 Paul Davis 
+    Copyright (C) 2000-2006 Paul Davis
 
     This program is free software; you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
 #include <sys/stat.h>
 #include <sys/mman.h>
 
-#include <pbd/error.h>
-#include <pbd/basename.h>
+#include "pbd/error.h"
 #include <glibmm/thread.h>
-#include <pbd/xml++.h>
-#include <pbd/memento_command.h>
-#include <pbd/enumwriter.h>
-
-#include <ardour/ardour.h>
-#include <ardour/audioengine.h>
-#include <ardour/audio_diskstream.h>
-#include <ardour/utils.h>
-#include <ardour/configuration.h>
-#include <ardour/audiofilesource.h>
-#include <ardour/send.h>
-#include <ardour/region_factory.h>
-#include <ardour/audioplaylist.h>
-#include <ardour/playlist_factory.h>
-#include <ardour/cycle_timer.h>
-#include <ardour/audioregion.h>
-#include <ardour/source_factory.h>
+#include "pbd/xml++.h"
+#include "pbd/memento_command.h"
+#include "pbd/enumwriter.h"
+#include "pbd/stacktrace.h"
+
+#include "ardour/analyser.h"
+#include "ardour/ardour.h"
+#include "ardour/audio_buffer.h"
+#include "ardour/audio_diskstream.h"
+#include "ardour/audio_port.h"
+#include "ardour/audioengine.h"
+#include "ardour/audiofilesource.h"
+
+#include "ardour/audioplaylist.h"
+#include "ardour/audioregion.h"
+#include "ardour/butler.h"
+#include "ardour/configuration.h"
+#include "ardour/cycle_timer.h"
+#include "ardour/debug.h"
+#include "ardour/io.h"
+#include "ardour/playlist_factory.h"
+#include "ardour/region_factory.h"
+#include "ardour/send.h"
+#include "ardour/session.h"
+#include "ardour/source_factory.h"
+#include "ardour/utils.h"
+#include "ardour/session_playlists.h"
 
 #include "i18n.h"
 #include <locale.h>
@@ -65,6 +74,7 @@ gain_t* AudioDiskstream::_gain_buffer          = 0;
 AudioDiskstream::AudioDiskstream (Session &sess, const string &name, Diskstream::Flag flag)
        : Diskstream(sess, name, flag)
        , deprecated_io_node(NULL)
+       , channels (new ChannelList)
 {
        /* prevent any write sources from being created */
 
@@ -75,15 +85,16 @@ AudioDiskstream::AudioDiskstream (Session &sess, const string &name, Diskstream:
 
        in_set_state = false;
 }
-       
+
 AudioDiskstream::AudioDiskstream (Session& sess, const XMLNode& node)
        : Diskstream(sess, node)
        , deprecated_io_node(NULL)
+       , channels (new ChannelList)
 {
        in_set_state = true;
        init (Recordable);
 
-       if (set_state (node)) {
+       if (set_state (node, Stateful::loading_state_version)) {
                in_set_state = false;
                throw failed_constructor();
        }
@@ -108,25 +119,26 @@ AudioDiskstream::init (Diskstream::Flag f)
        set_block_size (_session.get_block_size());
        allocate_temporary_buffers ();
 
-       add_channel ();
-       assert(_n_channels == 1);
+       add_channel (1);
+       assert(_n_channels == ChanCount(DataType::AUDIO, 1));
 }
 
 AudioDiskstream::~AudioDiskstream ()
 {
-       notify_callbacks ();
+       DEBUG_TRACE (DEBUG::Destruction, string_compose ("Audio Diskstream %1 destructor\n", _name));
 
        {
-               /* don't be holding this lock as we exit the destructor, glib will wince
-                  visibly since the mutex gets destroyed before we release it.
-               */
+               RCUWriter<ChannelList> writer (channels);
+               boost::shared_ptr<ChannelList> c = writer.get_copy();
 
-               Glib::Mutex::Lock lm (state_lock);
-               for (ChannelList::iterator chan = channels.begin(); chan != channels.end(); ++chan) {
-                       (*chan).release ();
+               for (ChannelList::iterator chan = c->begin(); chan != c->end(); ++chan) {
+                       delete *chan;
                }
-               channels.clear();
+
+               c->clear();
        }
+
+       channels.flush ();
 }
 
 void
@@ -152,40 +164,29 @@ AudioDiskstream::free_working_buffers()
 void
 AudioDiskstream::non_realtime_input_change ()
 {
-       { 
+       {
                Glib::Mutex::Lock lm (state_lock);
 
                if (input_change_pending == NoChange) {
                        return;
                }
 
-               if (input_change_pending & ConfigurationChanged) {
+               {
+                       RCUWriter<ChannelList> writer (channels);
+                       boost::shared_ptr<ChannelList> c = writer.get_copy();
 
-                       if (_io->n_inputs() > _n_channels) {
-                               
-                               // we need to add new channel infos
-                               
-                               int diff = _io->n_inputs() - channels.size();
-                               
-                               for (int i = 0; i < diff; ++i) {
-                                       add_channel ();
-                               }
-                               
-               } else if (_io->n_inputs() < _n_channels) {
-                               
-                               // we need to get rid of channels
-                               
-                               int diff = channels.size() - _io->n_inputs();
-                               
-                               for (int i = 0; i < diff; ++i) {
-                                       remove_channel ();
-                               }
+                       _n_channels.set(DataType::AUDIO, c->size());
+
+                       if (_io->n_ports().n_audio() > _n_channels.n_audio()) {
+                               add_channel_to (c, _io->n_ports().n_audio() - _n_channels.n_audio());
+                       } else if (_io->n_ports().n_audio() < _n_channels.n_audio()) {
+                               remove_channel_from (c, _n_channels.n_audio() - _io->n_ports().n_audio());
                        }
-               } 
+               }
 
                get_input_sources ();
                set_capture_offset ();
-               
+
                if (first_input_change) {
                        set_align_style (_persistent_alignment_style);
                        first_input_change = false;
@@ -194,6 +195,8 @@ AudioDiskstream::non_realtime_input_change ()
                }
 
                input_change_pending = NoChange;
+
+               /* implicit unlock */
        }
 
        /* reset capture files */
@@ -209,41 +212,53 @@ AudioDiskstream::non_realtime_input_change ()
        }
 }
 
+void
+AudioDiskstream::non_realtime_locate (nframes_t location)
+{
+       /* now refill channel buffers */
+
+       if (speed() != 1.0f || speed() != -1.0f) {
+               seek ((nframes_t) (location * (double) speed()));
+       } else {
+               seek (location);
+       }
+}
+
 void
 AudioDiskstream::get_input_sources ()
 {
-       uint32_t ni = _io->n_inputs();
-       
-       for (uint32_t n = 0; n < ni; ++n) {
-               
-               const char **connections = _io->input(n)->get_connections ();
-               ChannelInfo& chan = channels[n];
-               
-               if (connections == 0 || connections[0] == 0) {
-                       
-                       if (chan.source) {
+       boost::shared_ptr<ChannelList> c = channels.reader();
+
+       uint32_t n;
+       ChannelList::iterator chan;
+       uint32_t ni = _io->n_ports().n_audio();
+       vector<string> connections;
+
+       for (n = 0, chan = c->begin(); chan != c->end() && n < ni; ++chan, ++n) {
+
+               connections.clear ();
+
+               if (_io->nth (n)->get_connections (connections) == 0) {
+
+                       if ((*chan)->source) {
                                // _source->disable_metering ();
                        }
-                       
-                       chan.source = 0;
-                       
+
+                       (*chan)->source = 0;
+
                } else {
-                       chan.source = _session.engine().get_port_by_name (connections[0]);
-               }
-               
-               if (connections) {
-                       free (connections);
+                       (*chan)->source = dynamic_cast<AudioPort*>(_session.engine().get_port_by_name (connections[0]) );
                }
        }
-}              
+}
 
 int
 AudioDiskstream::find_and_use_playlist (const string& name)
 {
        boost::shared_ptr<AudioPlaylist> playlist;
-               
-       if ((playlist = boost::dynamic_pointer_cast<AudioPlaylist> (_session.playlist_by_name (name))) == 0) {
-               playlist = boost::dynamic_pointer_cast<AudioPlaylist> (PlaylistFactory::create (_session, name));
+
+       if ((playlist = boost::dynamic_pointer_cast<AudioPlaylist> (_session.playlists->by_name (name))) == 0) {
+               playlist = boost::dynamic_pointer_cast<AudioPlaylist> (PlaylistFactory::create (DataType::AUDIO, _session, name));
        }
 
        if (!playlist) {
@@ -280,12 +295,12 @@ AudioDiskstream::use_new_playlist ()
                newname = Playlist::bump_name (_name, _session);
        }
 
-       if ((playlist = boost::dynamic_pointer_cast<AudioPlaylist> (PlaylistFactory::create (_session, newname, hidden()))) != 0) {
-               
+       if ((playlist = boost::dynamic_pointer_cast<AudioPlaylist> (PlaylistFactory::create (DataType::AUDIO, _session, newname, hidden()))) != 0) {
+
                playlist->set_orig_diskstream_id (id());
                return use_playlist (playlist);
 
-       } else { 
+       } else {
                return -1;
        }
 }
@@ -308,11 +323,11 @@ AudioDiskstream::use_copy_playlist ()
        boost::shared_ptr<AudioPlaylist> playlist;
 
        newname = Playlist::bump_name (_playlist->name(), _session);
-       
+
        if ((playlist  = boost::dynamic_pointer_cast<AudioPlaylist>(PlaylistFactory::create (audio_playlist(), newname))) != 0) {
                playlist->set_orig_diskstream_id (id());
                return use_playlist (playlist);
-       } else { 
+       } else {
                return -1;
        }
 }
@@ -321,15 +336,16 @@ void
 AudioDiskstream::setup_destructive_playlist ()
 {
        SourceList srcs;
+       boost::shared_ptr<ChannelList> c = channels.reader();
 
-       for (ChannelList::iterator chan = channels.begin(); chan != channels.end(); ++chan) {
-               srcs.push_back ((*chan).write_source);
+       for (ChannelList::iterator chan = c->begin(); chan != c->end(); ++chan) {
+               srcs.push_back ((*chan)->write_source);
        }
 
        /* a single full-sized region */
 
        boost::shared_ptr<Region> region (RegionFactory::create (srcs, 0, max_frames - srcs.front()->natural_position(), _name));
-       _playlist->add_region (region, srcs.front()->natural_position());               
+       _playlist->add_region (region, srcs.front()->natural_position());
 }
 
 void
@@ -337,7 +353,7 @@ AudioDiskstream::use_destructive_playlist ()
 {
        /* this is called from the XML-based constructor or ::set_destructive. when called,
           we already have a playlist and a region, but we need to
-          set up our sources for write. we use the sources associated 
+          set up our sources for write. we use the sources associated
           with the (presumed single, full-extent) region.
        */
 
@@ -360,149 +376,51 @@ AudioDiskstream::use_destructive_playlist ()
 
        uint32_t n;
        ChannelList::iterator chan;
+       boost::shared_ptr<ChannelList> c = channels.reader();
 
-       for (n = 0, chan = channels.begin(); chan != channels.end(); ++chan, ++n) {
-               (*chan).write_source = boost::dynamic_pointer_cast<AudioFileSource>(region->source (n));
-               assert((*chan).write_source);
-               (*chan).write_source->set_allow_remove_if_empty (false);
+       for (n = 0, chan = c->begin(); chan != c->end(); ++chan, ++n) {
+               (*chan)->write_source = boost::dynamic_pointer_cast<AudioFileSource>(region->source (n));
+               assert((*chan)->write_source);
+               (*chan)->write_source->set_allow_remove_if_empty (false);
 
                /* this might be false if we switched modes, so force it */
 
-               (*chan).write_source->set_destructive (true);
+               (*chan)->write_source->set_destructive (true);
        }
 
        /* the source list will never be reset for a destructive track */
 }
 
 void
-AudioDiskstream::check_record_status (nframes_t transport_frame, nframes_t nframes, bool can_record)
+AudioDiskstream::prepare_record_status(nframes_t capture_start_frame)
 {
-       int possibly_recording;
-       int rolling;
-       int change;
-       const int transport_rolling = 0x4;
-       const int track_rec_enabled = 0x2;
-       const int global_rec_enabled = 0x1;
-
-       /* merge together the 3 factors that affect record status, and compute
-          what has changed.
-       */
-
-       rolling = _session.transport_speed() != 0.0f;
-       possibly_recording = (rolling << 2) | (record_enabled() << 1) | can_record;
-       change = possibly_recording ^ last_possibly_recording;
-
-       if (possibly_recording == last_possibly_recording) {
-               return;
-       }
-
-       /* change state */
-
-       /* if per-track or global rec-enable turned on while the other was already on, we've started recording */
-
-       if ((change & track_rec_enabled) && record_enabled() && (!(change & global_rec_enabled) && can_record) || 
-           ((change & global_rec_enabled) && can_record && (!(change & track_rec_enabled) && record_enabled()))) {
-               
-               /* starting to record: compute first+last frames */
-
-               first_recordable_frame = transport_frame + _capture_offset;
-               last_recordable_frame = max_frames;
-               capture_start_frame = transport_frame;
-
-               if (!(last_possibly_recording & transport_rolling) && (possibly_recording & transport_rolling)) {
-
-                       /* was stopped, now rolling (and recording) */
-
-                       if (_alignment_style == ExistingMaterial) {
-                               first_recordable_frame += _session.worst_output_latency();
-                       } else {
-                               first_recordable_frame += _roll_delay;
-                       }
-
-               } else {
-
-                       /* was rolling, but record state changed */
-
-                       if (_alignment_style == ExistingMaterial) {
-
-                               if (!Config->get_punch_in()) {
-
-                                       /* manual punch in happens at the correct transport frame
-                                          because the user hit a button. but to get alignment correct 
-                                          we have to back up the position of the new region to the 
-                                          appropriate spot given the roll delay.
-                                       */
-
-                                       capture_start_frame -= _roll_delay;
-
-                                       /* XXX paul notes (august 2005): i don't know why
-                                          this is needed.
-                                       */
-
-                                       first_recordable_frame += _capture_offset;
-
-                               } else {
-
-                                       /* autopunch toggles recording at the precise
-                                          transport frame, and then the DS waits
-                                          to start recording for a time that depends
-                                          on the output latency.
-                                       */
-
-                                       first_recordable_frame += _session.worst_output_latency();
-                               }
+       if (recordable() && destructive()) {
+               boost::shared_ptr<ChannelList> c = channels.reader();
+               for (ChannelList::iterator chan = c->begin(); chan != c->end(); ++chan) {
 
-                       } else {
+                       RingBufferNPT<CaptureTransition>::rw_vector transvec;
+                       (*chan)->capture_transition_buf->get_write_vector(&transvec);
 
-                               if (Config->get_punch_in()) {
-                                       first_recordable_frame += _roll_delay;
-                               } else {
-                                       capture_start_frame -= _roll_delay;
-                               }
+                       if (transvec.len[0] > 0) {
+                               transvec.buf[0]->type = CaptureStart;
+                               transvec.buf[0]->capture_val = capture_start_frame;
+                               (*chan)->capture_transition_buf->increment_write_ptr(1);
+                       }
+                       else {
+                               // bad!
+                               fatal << X_("programming error: capture_transition_buf is full on rec start!  inconceivable!")
+                                       << endmsg;
                        }
-                       
-               }
-
-               if (_flags & Recordable) {
-                       for (ChannelList::iterator chan = channels.begin(); chan != channels.end(); ++chan) {
-                               
-                               RingBufferNPT<CaptureTransition>::rw_vector transvec;
-                               (*chan).capture_transition_buf->get_write_vector(&transvec);
-                               
-                               if (transvec.len[0] > 0) {
-                                       transvec.buf[0]->type = CaptureStart;
-                                       transvec.buf[0]->capture_val = capture_start_frame;
-                                       (*chan).capture_transition_buf->increment_write_ptr(1);
-                               }
-                               else {
-                                       // bad!
-                                       fatal << X_("programming error: capture_transition_buf is full on rec start!  inconceivable!") 
-                                             << endmsg;
-                               }
-                       }
-               }
-
-       } else if (!record_enabled() || !can_record) {
-               
-               /* stop recording */
-
-               last_recordable_frame = transport_frame + _capture_offset;
-               
-               if (_alignment_style == ExistingMaterial) {
-                       last_recordable_frame += _session.worst_output_latency();
-               } else {
-                       last_recordable_frame += _roll_delay;
                }
        }
-
-       last_possibly_recording = possibly_recording;
 }
 
 int
-AudioDiskstream::process (nframes_t transport_frame, nframes_t nframes, nframes_t offset, bool can_record, bool rec_monitors_input)
+AudioDiskstream::process (nframes_t transport_frame, nframes_t nframes, bool can_record, bool rec_monitors_input)
 {
        uint32_t n;
-       ChannelList::iterator c;
+       boost::shared_ptr<ChannelList> c = channels.reader();
+       ChannelList::iterator chan;
        int ret = -1;
        nframes_t rec_offset = 0;
        nframes_t rec_nframes = 0;
@@ -522,6 +440,13 @@ AudioDiskstream::process (nframes_t transport_frame, nframes_t nframes, nframes_
                return 0;
        }
 
+       commit_should_unlock = false;
+
+       if (!_io || !_io->active()) {
+               _processed = true;
+               return 0;
+       }
+
        check_record_status (transport_frame, nframes, can_record);
 
        nominally_recording = (can_record && re);
@@ -540,59 +465,24 @@ AudioDiskstream::process (nframes_t transport_frame, nframes_t nframes, nframes_
        if (!state_lock.trylock()) {
                return 1;
        }
-
+       commit_should_unlock = true;
        adjust_capture_position = 0;
 
-       for (c = channels.begin(); c != channels.end(); ++c) {
-               (*c).current_capture_buffer = 0;
-               (*c).current_playback_buffer  = 0;
+       for (chan = c->begin(); chan != c->end(); ++chan) {
+               (*chan)->current_capture_buffer = 0;
+               (*chan)->current_playback_buffer = 0;
        }
 
-       if (nominally_recording || (_session.get_record_enabled() && Config->get_punch_in())) {
-               OverlapType ot;
-               
-               ot = coverage (first_recordable_frame, last_recordable_frame, transport_frame, transport_frame + nframes);
-
-               switch (ot) {
-               case OverlapNone:
-                       rec_nframes = 0;
-                       break;
-                       
-               case OverlapInternal:
-               /*     ----------    recrange
-                         |---|       transrange
-               */
-                       rec_nframes = nframes;
-                       rec_offset = 0;
-                       break;
-                       
-               case OverlapStart:
-                       /*    |--------|    recrange
-                            -----|          transrange
-                       */
-                       rec_nframes = transport_frame + nframes - first_recordable_frame;
-                       if (rec_nframes) {
-                               rec_offset = first_recordable_frame - transport_frame;
-                       }
-                       break;
-                       
-               case OverlapEnd:
-                       /*    |--------|    recrange
-                                 |--------  transrange
-                       */
-                       rec_nframes = last_recordable_frame - transport_frame;
-                       rec_offset = 0;
-                       break;
-                       
-               case OverlapExternal:
-                       /*    |--------|    recrange
-                            --------------  transrange
-                       */
-                       rec_nframes = last_recordable_frame - last_recordable_frame;
-                       rec_offset = first_recordable_frame - transport_frame;
-                       break;
+       if (nominally_recording || (_session.get_record_enabled() && _session.config.get_punch_in())) {
+               // Safeguard against situations where process() goes haywire when autopunching and last_recordable_frame < first_recordable_frame
+               if (last_recordable_frame < first_recordable_frame) {
+                       last_recordable_frame = max_frames;
                }
 
+               OverlapType ot = coverage (first_recordable_frame, last_recordable_frame, transport_frame, transport_frame + nframes);
+
+               calculate_record_range(ot, transport_frame, nframes, rec_nframes, rec_offset);
+
                if (rec_nframes && !was_recording) {
                        capture_captured = 0;
                        was_recording = true;
@@ -606,59 +496,75 @@ AudioDiskstream::process (nframes_t transport_frame, nframes_t nframes, nframes_
 
        if (nominally_recording || rec_nframes) {
 
-               for (n = 0, c = channels.begin(); c != channels.end(); ++c, ++n) {
-                       
-                       ChannelInfo& chan (*c);
-               
-                       chan.capture_buf->get_write_vector (&chan.capture_vector);
+               uint32_t limit = _io->n_ports ().n_audio();
+
+               /* one or more ports could already have been removed from _io, but our
+                  channel setup hasn't yet been updated. prevent us from trying to
+                  use channels that correspond to missing ports. note that the
+                  process callback (from which this is called) is always atomic
+                  with respect to port removal/addition.
+               */
+
+               for (n = 0, chan = c->begin(); chan != c->end() && n < limit; ++chan, ++n) {
+
+                       ChannelInfo* chaninfo (*chan);
+
+                       chaninfo->capture_buf->get_write_vector (&chaninfo->capture_vector);
 
-                       if (rec_nframes <= chan.capture_vector.len[0]) {
-                               
-                               chan.current_capture_buffer = chan.capture_vector.buf[0];
+                       if (rec_nframes <= chaninfo->capture_vector.len[0]) {
 
-                               /* note: grab the entire port buffer, but only copy what we were supposed to for recording, and use
-                                  rec_offset
+                               chaninfo->current_capture_buffer = chaninfo->capture_vector.buf[0];
+
+                               /* note: grab the entire port buffer, but only copy what we were supposed to
+                                  for recording, and use rec_offset
                                */
 
-                               memcpy (chan.current_capture_buffer, _io->input(n)->get_buffer (rec_nframes) + offset + rec_offset, sizeof (Sample) * rec_nframes);
+                               AudioPort* const ap = _io->audio (n);
+                               assert(ap);
+                               assert(rec_nframes <= ap->get_audio_buffer(nframes).capacity());
+                               memcpy (chaninfo->current_capture_buffer, ap->get_audio_buffer (rec_nframes).data(rec_offset), sizeof (Sample) * rec_nframes);
+
 
                        } else {
 
-                               nframes_t total = chan.capture_vector.len[0] + chan.capture_vector.len[1];
+                               nframes_t total = chaninfo->capture_vector.len[0] + chaninfo->capture_vector.len[1];
 
                                if (rec_nframes > total) {
                                        DiskOverrun ();
                                        goto out;
                                }
 
-                               Sample* buf = _io->input (n)->get_buffer (nframes) + offset;
-                               nframes_t first = chan.capture_vector.len[0];
+                               AudioPort* const ap = _io->audio (n);
+                               assert(ap);
+
+                               Sample* buf = ap->get_audio_buffer(nframes).data();
+                               nframes_t first = chaninfo->capture_vector.len[0];
 
-                               memcpy (chan.capture_wrap_buffer, buf, sizeof (Sample) * first);
-                               memcpy (chan.capture_vector.buf[0], buf, sizeof (Sample) * first);
-                               memcpy (chan.capture_wrap_buffer+first, buf + first, sizeof (Sample) * (rec_nframes - first));
-                               memcpy (chan.capture_vector.buf[1], buf + first, sizeof (Sample) * (rec_nframes - first));
-                               
-                               chan.current_capture_buffer = chan.capture_wrap_buffer;
+                               memcpy (chaninfo->capture_wrap_buffer, buf, sizeof (Sample) * first);
+                               memcpy (chaninfo->capture_vector.buf[0], buf, sizeof (Sample) * first);
+                               memcpy (chaninfo->capture_wrap_buffer+first, buf + first, sizeof (Sample) * (rec_nframes - first));
+                               memcpy (chaninfo->capture_vector.buf[1], buf + first, sizeof (Sample) * (rec_nframes - first));
+
+                               chaninfo->current_capture_buffer = chaninfo->capture_wrap_buffer;
                        }
                }
 
        } else {
 
                if (was_recording) {
-                       finish_capture (rec_monitors_input);
+                       finish_capture (rec_monitors_input, c);
                }
 
        }
-       
+
        if (rec_nframes) {
-               
+
                /* data will be written to disk */
 
                if (rec_nframes == nframes && rec_offset == 0) {
 
-                       for (c = channels.begin(); c != channels.end(); ++c) {
-                               (*c).current_playback_buffer = (*c).current_capture_buffer;
+                       for (chan = c->begin(); chan != c->end(); ++chan) {
+                               (*chan)->current_playback_buffer = (*chan)->current_capture_buffer;
                        }
 
                        playback_distance = nframes;
@@ -680,8 +586,8 @@ AudioDiskstream::process (nframes_t transport_frame, nframes_t nframes, nframes_
 
                /* can't do actual capture yet - waiting for latency effects to finish before we start*/
 
-               for (c = channels.begin(); c != channels.end(); ++c) {
-                       (*c).current_playback_buffer = (*c).current_capture_buffer;
+               for (chan = c->begin(); chan != c->end(); ++chan) {
+                       (*chan)->current_playback_buffer = (*chan)->current_capture_buffer;
                }
 
                playback_distance = nframes;
@@ -704,75 +610,53 @@ AudioDiskstream::process (nframes_t transport_frame, nframes_t nframes, nframes_
                } else {
                        necessary_samples = nframes;
                }
-               
-               for (c = channels.begin(); c != channels.end(); ++c) {
-                       (*c).playback_buf->get_read_vector (&(*c).playback_vector);
+
+               for (chan = c->begin(); chan != c->end(); ++chan) {
+                       (*chan)->playback_buf->get_read_vector (&(*chan)->playback_vector);
                }
 
-               n = 0;                  
+               n = 0;
+
+               for (chan = c->begin(); chan != c->end(); ++chan, ++n) {
 
-               for (c = channels.begin(); c != channels.end(); ++c, ++n) {
-               
-                       ChannelInfo& chan (*c);
+                       ChannelInfo* chaninfo (*chan);
 
-                       if (necessary_samples <= chan.playback_vector.len[0]) {
+                       if (necessary_samples <= chaninfo->playback_vector.len[0]) {
 
-                               chan.current_playback_buffer = chan.playback_vector.buf[0];
+                               chaninfo->current_playback_buffer = chaninfo->playback_vector.buf[0];
 
                        } else {
-                               nframes_t total = chan.playback_vector.len[0] + chan.playback_vector.len[1];
-                               
+                               nframes_t total = chaninfo->playback_vector.len[0] + chaninfo->playback_vector.len[1];
+
                                if (necessary_samples > total) {
+                                       cerr << _name << " Need " << necessary_samples << " total = " << total << endl;
+                                       cerr << "underrun for " << _name << endl;
                                        DiskUnderrun ();
                                        goto out;
-                                       
-                               } else {
-                                       
-                                       memcpy ((char *) chan.playback_wrap_buffer, chan.playback_vector.buf[0],
-                                               chan.playback_vector.len[0] * sizeof (Sample));
-                                       memcpy (chan.playback_wrap_buffer + chan.playback_vector.len[0], chan.playback_vector.buf[1], 
-                                               (necessary_samples - chan.playback_vector.len[0]) * sizeof (Sample));
-                                       
-                                       chan.current_playback_buffer = chan.playback_wrap_buffer;
-                               }
-                       }
-               } 
-
-               if (rec_nframes == 0 && _actual_speed != 1.0f && _actual_speed != -1.0f) {
-                       
-                       uint64_t phase = last_phase;
-                       nframes_t i = 0;
-
-                       // Linearly interpolate into the alt buffer
-                       // using 40.24 fixp maths (swh)
-
-                       for (c = channels.begin(); c != channels.end(); ++c) {
 
-                               float fr;
-                               ChannelInfo& chan (*c);
+                               } else {
 
-                               i = 0;
-                               phase = last_phase;
+                                       memcpy ((char *) chaninfo->playback_wrap_buffer,
+                                                       chaninfo->playback_vector.buf[0],
+                                                       chaninfo->playback_vector.len[0] * sizeof (Sample));
+                                       memcpy (chaninfo->playback_wrap_buffer + chaninfo->playback_vector.len[0],
+                                                       chaninfo->playback_vector.buf[1],
+                                                       (necessary_samples - chaninfo->playback_vector.len[0])
+                                                                       * sizeof (Sample));
 
-                               for (nframes_t outsample = 0; outsample < nframes; ++outsample) {
-                                       i = phase >> 24;
-                                       fr = (phase & 0xFFFFFF) / 16777216.0f;
-                                       chan.speed_buffer[outsample] = 
-                                               chan.current_playback_buffer[i] * (1.0f - fr) +
-                                               chan.current_playback_buffer[i+1] * fr;
-                                       phase += phi;
+                                       chaninfo->current_playback_buffer = chaninfo->playback_wrap_buffer;
                                }
-                               
-                               chan.current_playback_buffer = chan.speed_buffer;
                        }
+               }
 
-                       playback_distance = i + 1;
-                       last_phase = (phase & 0xFFFFFF);
-
+               if (rec_nframes == 0 && _actual_speed != 1.0f && _actual_speed != -1.0f) {
+                       process_varispeed_playback(nframes, c);
                } else {
                        playback_distance = nframes;
                }
 
+               _speed = _target_speed;
+
        }
 
        ret = 0;
@@ -785,46 +669,80 @@ AudioDiskstream::process (nframes_t transport_frame, nframes_t nframes, nframes_
                /* we're exiting with failure, so ::commit will not
                   be called. unlock the state lock.
                */
-               
+
+               commit_should_unlock = false;
                state_lock.unlock();
-       } 
+       }
 
        return ret;
 }
 
+void
+AudioDiskstream::process_varispeed_playback(nframes_t nframes, boost::shared_ptr<ChannelList> c)
+{
+       ChannelList::iterator chan;
+
+       interpolation.set_speed (_target_speed);
+
+       int channel = 0;
+       for (chan = c->begin(); chan != c->end(); ++chan, ++channel) {
+               ChannelInfo* chaninfo (*chan);
+
+               playback_distance = interpolation.interpolate (
+                               channel, nframes, chaninfo->current_playback_buffer, chaninfo->speed_buffer);
+
+               chaninfo->current_playback_buffer = chaninfo->speed_buffer;
+       }
+}
+
 bool
-AudioDiskstream::commit (nframes_t nframes)
+AudioDiskstream::commit (nframes_t /*nframes*/)
 {
        bool need_butler = false;
 
+       if (!_io || !_io->active()) {
+               return false;
+       }
+
        if (_actual_speed < 0.0) {
                playback_sample -= playback_distance;
        } else {
                playback_sample += playback_distance;
        }
 
-       for (ChannelList::iterator chan = channels.begin(); chan != channels.end(); ++chan) {
+       boost::shared_ptr<ChannelList> c = channels.reader();
+       for (ChannelList::iterator chan = c->begin(); chan != c->end(); ++chan) {
+
+               (*chan)->playback_buf->increment_read_ptr (playback_distance);
 
-               (*chan).playback_buf->increment_read_ptr (playback_distance);
-               
                if (adjust_capture_position) {
-                       (*chan).capture_buf->increment_write_ptr (adjust_capture_position);
+                       (*chan)->capture_buf->increment_write_ptr (adjust_capture_position);
                }
        }
-       
+
        if (adjust_capture_position != 0) {
                capture_captured += adjust_capture_position;
                adjust_capture_position = 0;
        }
-       
+
        if (_slaved) {
-               need_butler = channels[0].playback_buf->write_space() >= channels[0].playback_buf->bufsize() / 2;
+               if (_io && _io->active()) {
+                       need_butler = c->front()->playback_buf->write_space() >= c->front()->playback_buf->bufsize() / 2;
+               } else {
+                       need_butler = false;
+               }
        } else {
-               need_butler = channels[0].playback_buf->write_space() >= disk_io_chunk_frames
-                       || channels[0].capture_buf->read_space() >= disk_io_chunk_frames;
+               if (_io && _io->active()) {
+                       need_butler = c->front()->playback_buf->write_space() >= disk_io_chunk_frames
+                               || c->front()->capture_buf->read_space() >= disk_io_chunk_frames;
+               } else {
+                       need_butler = c->front()->capture_buf->read_space() >= disk_io_chunk_frames;
+               }
        }
 
-       state_lock.unlock();
+       if (commit_should_unlock) {
+               state_lock.unlock();
+       }
 
        _processed = false;
 
@@ -835,40 +753,41 @@ void
 AudioDiskstream::set_pending_overwrite (bool yn)
 {
        /* called from audio thread, so we can use the read ptr and playback sample as we wish */
-       
+
        pending_overwrite = yn;
 
        overwrite_frame = playback_sample;
-       overwrite_offset = channels.front().playback_buf->get_read_ptr();
+       overwrite_offset = channels.reader()->front()->playback_buf->get_read_ptr();
 }
 
 int
 AudioDiskstream::overwrite_existing_buffers ()
 {
-       Sample* mixdown_buffer;
-       float* gain_buffer;
-       int ret = -1;
+       boost::shared_ptr<ChannelList> c = channels.reader();
+       Sample* mixdown_buffer;
+       float* gain_buffer;
+       int ret = -1;
        bool reversed = (_visible_speed * _session.transport_speed()) < 0.0f;
 
        overwrite_queued = false;
 
        /* assume all are the same size */
-       nframes_t size = channels[0].playback_buf->bufsize();
-       
-       mixdown_buffer = new Sample[size];
-       gain_buffer = new float[size];
-       
+       nframes_t size = c->front()->playback_buf->bufsize();
+
+       mixdown_buffer = new Sample[size];
+       gain_buffer = new float[size];
+
        /* reduce size so that we can fill the buffer correctly. */
        size--;
-       
+
        uint32_t n=0;
        nframes_t start;
 
-       for (ChannelList::iterator chan = channels.begin(); chan != channels.end(); ++chan, ++n) {
+       for (ChannelList::iterator chan = c->begin(); chan != c->end(); ++chan, ++n) {
 
                start = overwrite_frame;
                nframes_t cnt = size;
-               
+
                /* to fill the buffer without resetting the playback sample, we need to
                   do it one or two chunks (normally two).
 
@@ -877,22 +796,22 @@ AudioDiskstream::overwrite_existing_buffers ()
                                       ^
                                       overwrite_offset
                    |<- second chunk->||<----------------- first chunk ------------------>|
-                  
+
                */
-               
+
                nframes_t to_read = size - overwrite_offset;
 
-               if (read ((*chan).playback_buf->buffer() + overwrite_offset, mixdown_buffer, gain_buffer, start, to_read, *chan, n, reversed)) {
+               if (read ((*chan)->playback_buf->buffer() + overwrite_offset, mixdown_buffer, gain_buffer, start, to_read, *chan, n, reversed)) {
                        error << string_compose(_("AudioDiskstream %1: when refilling, cannot read %2 from playlist at frame %3"),
                                         _id, size, playback_sample) << endmsg;
                        goto out;
                }
-                       
+
                if (cnt > to_read) {
 
                        cnt -= to_read;
-               
-                       if (read ((*chan).playback_buf->buffer(), mixdown_buffer, gain_buffer,
+
+                       if (read ((*chan)->playback_buf->buffer(), mixdown_buffer, gain_buffer,
                                  start, cnt, *chan, n, reversed)) {
                                error << string_compose(_("AudioDiskstream %1: when refilling, cannot read %2 from playlist at frame %3"),
                                                 _id, size, playback_sample) << endmsg;
@@ -902,27 +821,29 @@ AudioDiskstream::overwrite_existing_buffers ()
        }
 
        ret = 0;
+
   out:
        pending_overwrite = false;
-       delete [] gain_buffer;
-       delete [] mixdown_buffer;
-       return ret;
+       delete [] gain_buffer;
+       delete [] mixdown_buffer;
+       return ret;
 }
 
 int
 AudioDiskstream::seek (nframes_t frame, bool complete_refill)
 {
-       Glib::Mutex::Lock lm (state_lock);
        uint32_t n;
-       int ret;
+       int ret = -1;
        ChannelList::iterator chan;
+       boost::shared_ptr<ChannelList> c = channels.reader();
+
+       Glib::Mutex::Lock lm (state_lock);
 
-       for (n = 0, chan = channels.begin(); chan != channels.end(); ++chan, ++n) {
-               (*chan).playback_buf->reset ();
-               (*chan).capture_buf->reset ();
+       for (n = 0, chan = c->begin(); chan != c->end(); ++chan, ++n) {
+               (*chan)->playback_buf->reset ();
+               (*chan)->capture_buf->reset ();
        }
-       
+
        /* can't rec-enable in destructive mode if transport is before start */
 
        if (destructive() && record_enabled() && frame < _session.current_start_frame()) {
@@ -945,11 +866,12 @@ int
 AudioDiskstream::can_internal_playback_seek (nframes_t distance)
 {
        ChannelList::iterator chan;
+       boost::shared_ptr<ChannelList> c = channels.reader();
 
-       for (chan = channels.begin(); chan != channels.end(); ++chan) {
-               if ((*chan).playback_buf->read_space() < distance) {
+       for (chan = c->begin(); chan != c->end(); ++chan) {
+               if ((*chan)->playback_buf->read_space() < distance) {
                        return false;
-               } 
+               }
        }
        return true;
 }
@@ -958,20 +880,21 @@ int
 AudioDiskstream::internal_playback_seek (nframes_t distance)
 {
        ChannelList::iterator chan;
+       boost::shared_ptr<ChannelList> c = channels.reader();
 
-       for (chan = channels.begin(); chan != channels.end(); ++chan) {
-               (*chan).playback_buf->increment_read_ptr (distance);
+       for (chan = c->begin(); chan != c->end(); ++chan) {
+               (*chan)->playback_buf->increment_read_ptr (distance);
        }
 
        first_recordable_frame += distance;
        playback_sample += distance;
-       
+
        return 0;
 }
 
 int
-AudioDiskstream::read (Sample* buf, Sample* mixdown_buffer, float* gain_buffer, nframes_t& start, nframes_t cnt, 
-                 ChannelInfo& channel_info, int channel, bool reversed)
+AudioDiskstream::read (Sample* buf, Sample* mixdown_buffer, float* gain_buffer, nframes_t& start, nframes_t cnt,
+                      ChannelInfo* /*channel_info*/, int channel, bool reversed)
 {
        nframes_t this_read = 0;
        bool reloop = false;
@@ -986,23 +909,23 @@ AudioDiskstream::read (Sample* buf, Sample* mixdown_buffer, float* gain_buffer,
        if (!reversed) {
 
                /* Make the use of a Location atomic for this read operation.
-                  
+
                   Note: Locations don't get deleted, so all we care about
                   when I say "atomic" is that we are always pointing to
                   the same one and using a start/length values obtained
                   just once.
                */
-               
+
                if ((loc = loop_location) != 0) {
                        loop_start = loc->start();
                        loop_end = loc->end();
                        loop_length = loop_end - loop_start;
                }
-               
+
                /* if we are looping, ensure that the first frame we read is at the correct
                   position within the loop.
                */
-               
+
                if (loc && start >= loop_end) {
                        //cerr << "start adjusted from " << start;
                        start = loop_start + ((start - loop_start) % loop_length);
@@ -1017,7 +940,7 @@ AudioDiskstream::read (Sample* buf, Sample* mixdown_buffer, float* gain_buffer,
                if (reversed) {
                        start -= cnt;
                }
-                       
+
                /* take any loop into account. we can't read past the end of the loop. */
 
                if (loc && (loop_end - start < cnt)) {
@@ -1036,27 +959,27 @@ AudioDiskstream::read (Sample* buf, Sample* mixdown_buffer, float* gain_buffer,
                this_read = min(cnt,this_read);
 
                if (audio_playlist()->read (buf+offset, mixdown_buffer, gain_buffer, start, this_read, channel) != this_read) {
-                       error << string_compose(_("AudioDiskstream %1: cannot read %2 from playlist at frame %3"), _id, this_read, 
+                       error << string_compose(_("AudioDiskstream %1: cannot read %2 from playlist at frame %3"), _id, this_read,
                                         start) << endmsg;
                        return -1;
                }
 
                _read_data_count = _playlist->read_data_count();
-               
+
                if (reversed) {
 
                        swap_by_ptr (buf, buf + this_read - 1);
-                       
+
                } else {
-                       
+
                        /* if we read to the end of the loop, go back to the beginning */
-                       
+
                        if (reloop) {
                                start = loop_start;
                        } else {
                                start += this_read;
                        }
-               } 
+               }
 
                cnt -= this_read;
                offset += this_read;
@@ -1066,13 +989,13 @@ AudioDiskstream::read (Sample* buf, Sample* mixdown_buffer, float* gain_buffer,
 }
 
 int
-AudioDiskstream::do_refill_with_alloc()
+AudioDiskstream::do_refill_with_alloc ()
 {
        Sample* mix_buf  = new Sample[disk_io_chunk_frames];
        float*  gain_buf = new float[disk_io_chunk_frames];
 
        int ret = _do_refill(mix_buf, gain_buf);
-       
+
        delete [] mix_buf;
        delete [] gain_buf;
 
@@ -1090,13 +1013,23 @@ AudioDiskstream::_do_refill (Sample* mixdown_buffer, float* gain_buffer)
        nframes_t zero_fill;
        uint32_t chan_n;
        ChannelList::iterator i;
+       boost::shared_ptr<ChannelList> c = channels.reader();
        nframes_t ts;
 
+       if (c->empty()) {
+               return 0;
+       }
+
        assert(mixdown_buffer);
        assert(gain_buffer);
 
-       channels.front().playback_buf->get_write_vector (&vector);
-       
+       vector.buf[0] = 0;
+       vector.len[0] = 0;
+       vector.buf[1] = 0;
+       vector.len[1] = 0;
+
+       c->front()->playback_buf->get_write_vector (&vector);
+
        if ((total_space = vector.len[0] + vector.len[1]) == 0) {
                return 0;
        }
@@ -1105,28 +1038,28 @@ AudioDiskstream::_do_refill (Sample* mixdown_buffer, float* gain_buffer)
           this track, let the caller know so that it can arrange
           for us to be called again, ASAP.
        */
-       
+
        if (total_space >= (_slaved?3:2) * disk_io_chunk_frames) {
                ret = 1;
        }
-       
-       /* if we're running close to normal speed and there isn't enough 
-          space to do disk_io_chunk_frames of I/O, then don't bother.  
-          
+
+       /* if we're running close to normal speed and there isn't enough
+          space to do disk_io_chunk_frames of I/O, then don't bother.
+
           at higher speeds, just do it because the sync between butler
           and audio thread may not be good enough.
        */
-       
+
        if ((total_space < disk_io_chunk_frames) && fabs (_actual_speed) < 2.0f) {
                return 0;
        }
-       
+
        /* when slaved, don't try to get too close to the read pointer. this
           leaves space for the buffer reversal to have something useful to
           work with.
        */
-       
-       if (_slaved && total_space < (channels.front().playback_buf->bufsize() / 2)) {
+
+       if (_slaved && total_space < (c->front()->playback_buf->bufsize() / 2)) {
                return 0;
        }
 
@@ -1140,23 +1073,23 @@ AudioDiskstream::_do_refill (Sample* mixdown_buffer, float* gain_buffer)
 
                        /* at start: nothing to do but fill with silence */
 
-                       for (chan_n = 0, i = channels.begin(); i != channels.end(); ++i, ++chan_n) {
-                                       
-                               ChannelInfo& chan (*i);
-                               chan.playback_buf->get_write_vector (&vector);
+                       for (chan_n = 0, i = c->begin(); i != c->end(); ++i, ++chan_n) {
+
+                               ChannelInfo* chan (*i);
+                               chan->playback_buf->get_write_vector (&vector);
                                memset (vector.buf[0], 0, sizeof(Sample) * vector.len[0]);
                                if (vector.len[1]) {
                                        memset (vector.buf[1], 0, sizeof(Sample) * vector.len[1]);
                                }
-                               chan.playback_buf->increment_write_ptr (vector.len[0] + vector.len[1]);
+                               chan->playback_buf->increment_write_ptr (vector.len[0] + vector.len[1]);
                        }
                        return 0;
                }
 
                if (file_frame < total_space) {
 
-                       /* too close to the start: read what we can, 
-                          and then zero fill the rest 
+                       /* too close to the start: read what we can,
+                          and then zero fill the rest
                        */
 
                        zero_fill = total_space - file_frame;
@@ -1164,7 +1097,7 @@ AudioDiskstream::_do_refill (Sample* mixdown_buffer, float* gain_buffer)
                        file_frame = 0;
 
                } else {
-                       
+
                        zero_fill = 0;
                }
 
@@ -1173,20 +1106,20 @@ AudioDiskstream::_do_refill (Sample* mixdown_buffer, float* gain_buffer)
                if (file_frame == max_frames) {
 
                        /* at end: nothing to do but fill with silence */
-                       
-                       for (chan_n = 0, i = channels.begin(); i != channels.end(); ++i, ++chan_n) {
-                                       
-                               ChannelInfo& chan (*i);
-                               chan.playback_buf->get_write_vector (&vector);
+
+                       for (chan_n = 0, i = c->begin(); i != c->end(); ++i, ++chan_n) {
+
+                               ChannelInfo* chan (*i);
+                               chan->playback_buf->get_write_vector (&vector);
                                memset (vector.buf[0], 0, sizeof(Sample) * vector.len[0]);
                                if (vector.len[1]) {
                                        memset (vector.buf[1], 0, sizeof(Sample) * vector.len[1]);
                                }
-                               chan.playback_buf->increment_write_ptr (vector.len[0] + vector.len[1]);
+                               chan->playback_buf->increment_write_ptr (vector.len[0] + vector.len[1]);
                        }
                        return 0;
                }
-               
+
                if (file_frame > max_frames - total_space) {
 
                        /* to close to the end: read what we can, and zero fill the rest */
@@ -1198,40 +1131,40 @@ AudioDiskstream::_do_refill (Sample* mixdown_buffer, float* gain_buffer)
                        zero_fill = 0;
                }
        }
-       
+
        nframes_t file_frame_tmp = 0;
 
-       for (chan_n = 0, i = channels.begin(); i != channels.end(); ++i, ++chan_n) {
+       for (chan_n = 0, i = c->begin(); i != c->end(); ++i, ++chan_n) {
 
-               ChannelInfo& chan (*i);
+               ChannelInfo* chan (*i);
                Sample* buf1;
                Sample* buf2;
                nframes_t len1, len2;
 
-               chan.playback_buf->get_write_vector (&vector);
+               chan->playback_buf->get_write_vector (&vector);
 
                if (vector.len[0] > disk_io_chunk_frames) {
-                       
+
                        /* we're not going to fill the first chunk, so certainly do not bother with the
                           other part. it won't be connected with the part we do fill, as in:
-                          
+
                           .... => writable space
                           ++++ => readable space
                           ^^^^ => 1 x disk_io_chunk_frames that would be filled
-                          
+
                           |......|+++++++++++++|...............................|
                           buf1                buf0
                                                ^^^^^^^^^^^^^^^
-                          
-                          
-                          So, just pretend that the buf1 part isn't there.                                     
-                          
+
+
+                          So, just pretend that the buf1 part isn't there.
+
                        */
-               
+
                        vector.buf[1] = 0;
                        vector.len[1] = 0;
-               
-               } 
+
+               }
 
                ts = total_space;
                file_frame_tmp = file_frame;
@@ -1251,7 +1184,7 @@ AudioDiskstream::_do_refill (Sample* mixdown_buffer, float* gain_buffer)
                                goto out;
                        }
 
-                       chan.playback_buf->increment_write_ptr (to_read);
+                       chan->playback_buf->increment_write_ptr (to_read);
                        ts -= to_read;
                }
 
@@ -1267,8 +1200,8 @@ AudioDiskstream::_do_refill (Sample* mixdown_buffer, float* gain_buffer)
                                ret = -1;
                                goto out;
                        }
-               
-                       chan.playback_buf->increment_write_ptr (to_read);
+
+                       chan->playback_buf->increment_write_ptr (to_read);
                }
 
                if (zero_fill) {
@@ -1276,13 +1209,13 @@ AudioDiskstream::_do_refill (Sample* mixdown_buffer, float* gain_buffer)
                }
 
        }
-       
+
        file_frame = file_frame_tmp;
 
   out:
 
        return ret;
-}      
+}
 
 /** Flush pending data to disk.
  *
@@ -1290,12 +1223,12 @@ AudioDiskstream::_do_refill (Sample* mixdown_buffer, float* gain_buffer)
  * of data to disk. it will never write more than that.  If it writes that
  * much and there is more than that waiting to be written, it will return 1,
  * otherwise 0 on success or -1 on failure.
- * 
+ *
  * If there is less than disk_io_chunk_frames to be written, no data will be
  * written at all unless @a force_flush is true.
  */
 int
-AudioDiskstream::do_flush (Session::RunContext context, bool force_flush)
+AudioDiskstream::do_flush (RunContext /*context*/, bool force_flush)
 {
        uint32_t to_write;
        int32_t ret = 0;
@@ -1305,13 +1238,18 @@ AudioDiskstream::do_flush (Session::RunContext context, bool force_flush)
 
        _write_data_count = 0;
 
-       for (ChannelList::iterator chan = channels.begin(); chan != channels.end(); ++chan) {
-       
-               (*chan).capture_buf->get_read_vector (&vector);
+       transvec.buf[0] = 0;
+       transvec.buf[1] = 0;
+       vector.buf[0] = 0;
+       vector.buf[1] = 0;
+
+       boost::shared_ptr<ChannelList> c = channels.reader();
+       for (ChannelList::iterator chan = c->begin(); chan != c->end(); ++chan) {
+
+               (*chan)->capture_buf->get_read_vector (&vector);
 
                total = vector.len[0] + vector.len[1];
 
-               
                if (total == 0 || (total < disk_io_chunk_frames && !force_flush && was_recording)) {
                        goto out;
                }
@@ -1319,7 +1257,7 @@ AudioDiskstream::do_flush (Session::RunContext context, bool force_flush)
                /* if there are 2+ chunks of disk i/o possible for
                   this track, let the caller know so that it can arrange
                   for us to be called again, ASAP.
-                  
+
                   if we are forcing a flush, then if there is* any* extra
                   work, let the caller know.
 
@@ -1329,27 +1267,27 @@ AudioDiskstream::do_flush (Session::RunContext context, bool force_flush)
 
                if (total >= 2 * disk_io_chunk_frames || ((force_flush || !was_recording) && total > disk_io_chunk_frames)) {
                        ret = 1;
-               } 
+               }
 
                to_write = min (disk_io_chunk_frames, (nframes_t) vector.len[0]);
-               
+
                // check the transition buffer when recording destructive
                // important that we get this after the capture buf
 
                if (destructive()) {
-                       (*chan).capture_transition_buf->get_read_vector(&transvec);
+                       (*chan)->capture_transition_buf->get_read_vector(&transvec);
                        size_t transcount = transvec.len[0] + transvec.len[1];
                        bool have_start = false;
                        size_t ti;
 
                        for (ti=0; ti < transcount; ++ti) {
                                CaptureTransition & captrans = (ti < transvec.len[0]) ? transvec.buf[0][ti] : transvec.buf[1][ti-transvec.len[0]];
-                               
+
                                if (captrans.type == CaptureStart) {
                                        // by definition, the first data we got above represents the given capture pos
 
-                                       (*chan).write_source->mark_capture_start (captrans.capture_val);
-                                       (*chan).curr_capture_cnt = 0;
+                                       (*chan)->write_source->mark_capture_start (captrans.capture_val);
+                                       (*chan)->curr_capture_cnt = 0;
 
                                        have_start = true;
                                }
@@ -1357,18 +1295,18 @@ AudioDiskstream::do_flush (Session::RunContext context, bool force_flush)
 
                                        // capture end, the capture_val represents total frames in capture
 
-                                       if (captrans.capture_val <= (*chan).curr_capture_cnt + to_write) {
+                                       if (captrans.capture_val <= (*chan)->curr_capture_cnt + to_write) {
 
                                                // shorten to make the write a perfect fit
-                                               uint32_t nto_write = (captrans.capture_val - (*chan).curr_capture_cnt); 
+                                               uint32_t nto_write = (captrans.capture_val - (*chan)->curr_capture_cnt);
 
                                                if (nto_write < to_write) {
                                                        ret = 1; // should we?
                                                }
                                                to_write = nto_write;
 
-                                               (*chan).write_source->mark_capture_end ();
-                                               
+                                               (*chan)->write_source->mark_capture_end ();
+
                                                // increment past this transition, but go no further
                                                ++ti;
                                                break;
@@ -1382,36 +1320,36 @@ AudioDiskstream::do_flush (Session::RunContext context, bool force_flush)
                        }
 
                        if (ti > 0) {
-                               (*chan).capture_transition_buf->increment_read_ptr(ti);
+                               (*chan)->capture_transition_buf->increment_read_ptr(ti);
                        }
                }
 
-               if ((!(*chan).write_source) || (*chan).write_source->write (vector.buf[0], to_write) != to_write) {
+               if ((!(*chan)->write_source) || (*chan)->write_source->write (vector.buf[0], to_write) != to_write) {
                        error << string_compose(_("AudioDiskstream %1: cannot write to disk"), _id) << endmsg;
                        return -1;
                }
 
-               (*chan).capture_buf->increment_read_ptr (to_write);
-               (*chan).curr_capture_cnt += to_write;
-               
+               (*chan)->capture_buf->increment_read_ptr (to_write);
+               (*chan)->curr_capture_cnt += to_write;
+
                if ((to_write == vector.len[0]) && (total > to_write) && (to_write < disk_io_chunk_frames) && !destructive()) {
-               
+
                        /* we wrote all of vector.len[0] but it wasn't an entire
-                          disk_io_chunk_frames of data, so arrange for some part 
+                          disk_io_chunk_frames of data, so arrange for some part
                           of vector.len[1] to be flushed to disk as well.
                        */
-               
+
                        to_write = min ((nframes_t)(disk_io_chunk_frames - to_write), (nframes_t) vector.len[1]);
-               
-                       if ((*chan).write_source->write (vector.buf[1], to_write) != to_write) {
+
+                       if ((*chan)->write_source->write (vector.buf[1], to_write) != to_write) {
                                error << string_compose(_("AudioDiskstream %1: cannot write to disk"), _id) << endmsg;
                                return -1;
                        }
 
-                       _write_data_count += (*chan).write_source->write_data_count();
-       
-                       (*chan).capture_buf->increment_read_ptr (to_write);
-                       (*chan).curr_capture_cnt += to_write;
+                       _write_data_count += (*chan)->write_source->write_data_count();
+
+                       (*chan)->capture_buf->increment_read_ptr (to_write);
+                       (*chan)->curr_capture_cnt += to_write;
                }
        }
 
@@ -1431,17 +1369,18 @@ AudioDiskstream::transport_stopped (struct tm& when, time_t twhen, bool abort_ca
        SourceList::iterator src;
        ChannelList::iterator chan;
        vector<CaptureInfo*>::iterator ci;
-       uint32_t n = 0; 
+       boost::shared_ptr<ChannelList> c = channels.reader();
+       uint32_t n = 0;
        bool mark_write_completed = false;
 
-       finish_capture (true);
+       finish_capture (true, c);
 
-       /* butler is already stopped, but there may be work to do 
+       /* butler is already stopped, but there may be work to do
           to flush remaining data to disk.
        */
 
        while (more_work && !err) {
-               switch (do_flush (Session::TransportContext, true)) {
+               switch (do_flush (TransportContext, true)) {
                case 0:
                        more_work = false;
                        break;
@@ -1455,31 +1394,31 @@ AudioDiskstream::transport_stopped (struct tm& when, time_t twhen, bool abort_ca
 
        /* XXX is there anything we can do if err != 0 ? */
        Glib::Mutex::Lock lm (capture_info_lock);
-       
+
        if (capture_info.empty()) {
                return;
        }
 
        if (abort_capture) {
-               
+
                if (destructive()) {
                        goto outout;
                }
 
-               for (ChannelList::iterator chan = channels.begin(); chan != channels.end(); ++chan) {
+               for (ChannelList::iterator chan = c->begin(); chan != c->end(); ++chan) {
+
+                       if ((*chan)->write_source) {
 
-                       if ((*chan).write_source) {
-                               
-                               (*chan).write_source->mark_for_remove ();
-                               (*chan).write_source->drop_references ();
-                               (*chan).write_source.reset ();
+                               (*chan)->write_source->mark_for_remove ();
+                               (*chan)->write_source->drop_references ();
+                               (*chan)->write_source.reset ();
                        }
-                       
+
                        /* new source set up in "out" below */
                }
 
                goto out;
-       } 
+       }
 
        for (total_capture = 0, ci = capture_info.begin(); ci != capture_info.end(); ++ci) {
                total_capture += (*ci)->frames;
@@ -1487,15 +1426,18 @@ AudioDiskstream::transport_stopped (struct tm& when, time_t twhen, bool abort_ca
 
        /* figure out the name for this take */
 
-       for (n = 0, chan = channels.begin(); chan != channels.end(); ++chan, ++n) {
+       for (n = 0, chan = c->begin(); chan != c->end(); ++chan, ++n) {
+
+               boost::shared_ptr<AudioFileSource> s = (*chan)->write_source;
 
-               boost::shared_ptr<AudioFileSource> s = (*chan).write_source;
-               
                if (s) {
                        srcs.push_back (s);
                        s->update_header (capture_info.front()->start, when, twhen);
                        s->set_captured_for (_name);
                        s->mark_immutable ();
+                       if (Config->get_auto_analyse_audio()) {
+                               Analyser::queue_source_for_analysis (s, true);
+                       }
                }
        }
 
@@ -1503,78 +1445,79 @@ AudioDiskstream::transport_stopped (struct tm& when, time_t twhen, bool abort_ca
 
        if (destructive()) {
 
-               /* send a signal that any UI can pick up to do the right thing. there is 
+               /* send a signal that any UI can pick up to do the right thing. there is
                   a small problem here in that a UI may need the peak data to be ready
                   for the data that was recorded and this isn't interlocked with that
                   process. this problem is deferred to the UI.
                 */
-               
+
                _playlist->Modified();
 
        } else {
 
                string whole_file_region_name;
-               whole_file_region_name = region_name_from_path (channels[0].write_source->name(), true);
+               whole_file_region_name = region_name_from_path (c->front()->write_source->name(), true);
 
                /* Register a new region with the Session that
                   describes the entire source. Do this first
                   so that any sub-regions will obviously be
                   children of this one (later!)
                */
-               
+
                try {
-                       boost::shared_ptr<Region> rx (RegionFactory::create (srcs, channels[0].write_source->last_capture_start_frame(), total_capture, 
-                                                                            whole_file_region_name,
-                                                                            0, AudioRegion::Flag (AudioRegion::DefaultFlags|AudioRegion::Automatic|AudioRegion::WholeFile)));
+                       boost::shared_ptr<Region> rx (RegionFactory::create (srcs,
+                                               c->front()->write_source->last_capture_start_frame(), total_capture,
+                                               whole_file_region_name, 0,
+                                               Region::Flag (Region::DefaultFlags|Region::Automatic|Region::WholeFile)));
 
                        region = boost::dynamic_pointer_cast<AudioRegion> (rx);
                        region->special_set_position (capture_info.front()->start);
                }
-               
-               
+
+
                catch (failed_constructor& err) {
                        error << string_compose(_("%1: could not create region for complete audio file"), _name) << endmsg;
                        /* XXX what now? */
                }
-               
+
                _last_capture_regions.push_back (region);
 
                // cerr << _name << ": there are " << capture_info.size() << " capture_info records\n";
-               
-                XMLNode &before = _playlist->get_state();
+
+               XMLNode &before = _playlist->get_state();
                _playlist->freeze ();
-               
-               for (buffer_position = channels[0].write_source->last_capture_start_frame(), ci = capture_info.begin(); ci != capture_info.end(); ++ci) {
-                       
+
+               for (buffer_position = c->front()->write_source->last_capture_start_frame(), ci = capture_info.begin(); ci != capture_info.end(); ++ci) {
+
                        string region_name;
 
                        _session.region_name (region_name, whole_file_region_name, false);
-                       
+
                        // cerr << _name << ": based on ci of " << (*ci)->start << " for " << (*ci)->frames << " add region " << region_name << endl;
-                       
+
                        try {
                                boost::shared_ptr<Region> rx (RegionFactory::create (srcs, buffer_position, (*ci)->frames, region_name));
                                region = boost::dynamic_pointer_cast<AudioRegion> (rx);
                        }
-                       
+
                        catch (failed_constructor& err) {
                                error << _("AudioDiskstream: could not create region for captured audio!") << endmsg;
                                continue; /* XXX is this OK? */
                        }
-                       
-                       region->GoingAway.connect (bind (mem_fun (*this, &Diskstream::remove_region_from_last_capture), boost::weak_ptr<Region>(region)));
-                       
+
+                       region->DropReferences.connect_same_thread (*this, boost::bind (&Diskstream::remove_region_from_last_capture, this, boost::weak_ptr<Region>(region)));
+
                        _last_capture_regions.push_back (region);
-                       
+
                        i_am_the_modifier++;
-                       _playlist->add_region (region, (*ci)->start);
+                       _playlist->add_region (region, (*ci)->start, 1, non_layered());
                        i_am_the_modifier--;
-                       
+
                        buffer_position += (*ci)->frames;
                }
 
                _playlist->thaw ();
-                XMLNode &after = _playlist->get_state();
+               XMLNode &after = _playlist->get_state();
                _session.add_command (new MementoCommand<Playlist>(*_playlist, &before, &after));
        }
 
@@ -1594,25 +1537,75 @@ AudioDiskstream::transport_stopped (struct tm& when, time_t twhen, bool abort_ca
 }
 
 void
-AudioDiskstream::finish_capture (bool rec_monitors_input)
+AudioDiskstream::transport_looped (nframes_t transport_frame)
+{
+       if (was_recording) {
+               // all we need to do is finish this capture, with modified capture length
+               boost::shared_ptr<ChannelList> c = channels.reader();
+
+               // adjust the capture length knowing that the data will be recorded to disk
+               // only necessary after the first loop where we're recording
+               if (capture_info.size() == 0) {
+                       capture_captured += _capture_offset;
+
+                       if (_alignment_style == ExistingMaterial) {
+                               capture_captured += _session.worst_output_latency();
+                       } else {
+                               capture_captured += _roll_delay;
+                       }
+               }
+
+               finish_capture (true, c);
+
+               // the next region will start recording via the normal mechanism
+               // we'll set the start position to the current transport pos
+               // no latency adjustment or capture offset needs to be made, as that already happened the first time
+               capture_start_frame = transport_frame;
+               first_recordable_frame = transport_frame; // mild lie
+               last_recordable_frame = max_frames;
+               was_recording = true;
+
+               if (recordable() && destructive()) {
+                       for (ChannelList::iterator chan = c->begin(); chan != c->end(); ++chan) {
+
+                               RingBufferNPT<CaptureTransition>::rw_vector transvec;
+                               (*chan)->capture_transition_buf->get_write_vector(&transvec);
+
+                               if (transvec.len[0] > 0) {
+                                       transvec.buf[0]->type = CaptureStart;
+                                       transvec.buf[0]->capture_val = capture_start_frame;
+                                       (*chan)->capture_transition_buf->increment_write_ptr(1);
+                               }
+                               else {
+                                       // bad!
+                                       fatal << X_("programming error: capture_transition_buf is full on rec loop!  inconceivable!")
+                                             << endmsg;
+                               }
+                       }
+               }
+
+       }
+}
+
+void
+AudioDiskstream::finish_capture (bool /*rec_monitors_input*/, boost::shared_ptr<ChannelList> c)
 {
        was_recording = false;
-       
+
        if (capture_captured == 0) {
                return;
        }
 
        if (recordable() && destructive()) {
-               for (ChannelList::iterator chan = channels.begin(); chan != channels.end(); ++chan) {
-                       
+               for (ChannelList::iterator chan = c->begin(); chan != c->end(); ++chan) {
+
                        RingBufferNPT<CaptureTransition>::rw_vector transvec;
-                       (*chan).capture_transition_buf->get_write_vector(&transvec);
-                       
-                       
+                       (*chan)->capture_transition_buf->get_write_vector(&transvec);
+
                        if (transvec.len[0] > 0) {
                                transvec.buf[0]->type = CaptureEnd;
                                transvec.buf[0]->capture_val = capture_captured;
-                               (*chan).capture_transition_buf->increment_write_ptr(1);
+                               (*chan)->capture_transition_buf->increment_write_ptr(1);
                        }
                        else {
                                // bad!
@@ -1620,15 +1613,15 @@ AudioDiskstream::finish_capture (bool rec_monitors_input)
                        }
                }
        }
-       
-       
+
+
        CaptureInfo* ci = new CaptureInfo;
-       
+
        ci->start =  capture_start_frame;
        ci->frames = capture_captured;
-       
-       /* XXX theoretical race condition here. Need atomic exchange ? 
-          However, the circumstances when this is called right 
+
+       /* XXX theoretical race condition here. Need atomic exchange ?
+          However, the circumstances when this is called right
           now (either on record-disable or transport_stopped)
           mean that no actual race exists. I think ...
           We now have a capture_info_lock, but it is only to be used
@@ -1640,12 +1633,15 @@ AudioDiskstream::finish_capture (bool rec_monitors_input)
 
        capture_info.push_back (ci);
        capture_captured = 0;
+
+       /* now we've finished a capture, reset first_recordable_frame for next time */
+       first_recordable_frame = max_frames;
 }
 
 void
 AudioDiskstream::set_record_enabled (bool yn)
 {
-       if (!recordable() || !_session.record_enabling_legal() || _io->n_inputs() == 0) {
+       if (!recordable() || !_session.record_enabling_legal() || _io->n_ports().n_audio() == 0) {
                return;
        }
 
@@ -1655,15 +1651,6 @@ AudioDiskstream::set_record_enabled (bool yn)
                return;
        }
 
-       if (yn && channels[0].source == 0) {
-
-               /* pick up connections not initiated *from* the IO object
-                  we're associated with.
-               */
-
-               get_input_sources ();
-       }
-
        /* yes, i know that this not proof against race conditions, but its
           good enough. i think.
        */
@@ -1680,20 +1667,26 @@ AudioDiskstream::set_record_enabled (bool yn)
 void
 AudioDiskstream::engage_record_enable ()
 {
-    bool rolling = _session.transport_speed() != 0.0f;
+       bool rolling = _session.transport_speed() != 0.0f;
+       boost::shared_ptr<ChannelList> c = channels.reader();
 
        g_atomic_int_set (&_record_enabled, 1);
        capturing_sources.clear ();
+
        if (Config->get_monitoring_model() == HardwareMonitoring) {
-               for (ChannelList::iterator chan = channels.begin(); chan != channels.end(); ++chan) {
-                       if ((*chan).source) {
-                               (*chan).source->ensure_monitor_input (!(Config->get_auto_input() && rolling));
+
+               for (ChannelList::iterator chan = c->begin(); chan != c->end(); ++chan) {
+                       if ((*chan)->source) {
+                               (*chan)->source->ensure_monitor_input (!(_session.config.get_auto_input() && rolling));
                        }
-                       capturing_sources.push_back ((*chan).write_source);
+                       capturing_sources.push_back ((*chan)->write_source);
+                       (*chan)->write_source->mark_streaming_write_started ();
                }
+
        } else {
-               for (ChannelList::iterator chan = channels.begin(); chan != channels.end(); ++chan) {
-                       capturing_sources.push_back ((*chan).write_source);
+               for (ChannelList::iterator chan = c->begin(); chan != c->end(); ++chan) {
+                       capturing_sources.push_back ((*chan)->write_source);
+                       (*chan)->write_source->mark_streaming_write_started ();
                }
        }
 
@@ -1704,17 +1697,17 @@ void
 AudioDiskstream::disengage_record_enable ()
 {
        g_atomic_int_set (&_record_enabled, 0);
+       boost::shared_ptr<ChannelList> c = channels.reader();
        if (Config->get_monitoring_model() == HardwareMonitoring) {
-               for (ChannelList::iterator chan = channels.begin(); chan != channels.end(); ++chan) {
-                       if ((*chan).source) {
-                               (*chan).source->ensure_monitor_input (false);
+               for (ChannelList::iterator chan = c->begin(); chan != c->end(); ++chan) {
+                       if ((*chan)->source) {
+                               (*chan)->source->ensure_monitor_input (false);
                        }
                }
        }
        capturing_sources.clear ();
        RecordEnableChanged (); /* EMIT SIGNAL */
 }
-               
 
 XMLNode&
 AudioDiskstream::get_state ()
@@ -1722,14 +1715,15 @@ AudioDiskstream::get_state ()
        XMLNode* node = new XMLNode ("AudioDiskstream");
        char buf[64] = "";
        LocaleGuard lg (X_("POSIX"));
+       boost::shared_ptr<ChannelList> c = channels.reader();
 
        node->add_property ("flags", enum_2_string (_flags));
 
-       snprintf (buf, sizeof(buf), "%zd", channels.size());
+       snprintf (buf, sizeof(buf), "%zd", c->size());
        node->add_property ("channels", buf);
 
        node->add_property ("playlist", _playlist->name());
-       
+
        snprintf (buf, sizeof(buf), "%.12g", _visible_speed);
        node->add_property ("speed", buf);
 
@@ -1752,10 +1746,10 @@ AudioDiskstream::get_state ()
 
                Location* pi;
 
-               if (Config->get_punch_in() && ((pi = _session.locations()->auto_punch_location()) != 0)) {
-                       snprintf (buf, sizeof (buf), "%" PRIu32, pi->start());
+               if (_session.config.get_punch_in() && ((pi = _session.locations()->auto_punch_location()) != 0)) {
+                       snprintf (buf, sizeof (buf), "%" PRId64, pi->start());
                } else {
-                       snprintf (buf, sizeof (buf), "%" PRIu32, _session.transport_frame());
+                       snprintf (buf, sizeof (buf), "%" PRId64, _session.transport_frame());
                }
 
                cs_child->add_property (X_("at"), buf);
@@ -1770,7 +1764,7 @@ AudioDiskstream::get_state ()
 }
 
 int
-AudioDiskstream::set_state (const XMLNode& node)
+AudioDiskstream::set_state (const XMLNode& node, int /*version*/)
 {
        const XMLProperty* prop;
        XMLNodeList nlist = node.children();
@@ -1781,23 +1775,23 @@ AudioDiskstream::set_state (const XMLNode& node)
 
        in_set_state = true;
 
-       for (niter = nlist.begin(); niter != nlist.end(); ++niter) {
-               if ((*niter)->name() == IO::state_node_name) {
+       for (niter = nlist.begin(); niter != nlist.end(); ++niter) {
+               if ((*niter)->name() == IO::state_node_name) {
                        deprecated_io_node = new XMLNode (**niter);
-               }
+               }
 
                if ((*niter)->name() == X_("CapturingSources")) {
                        capture_pending_node = *niter;
                }
-       }
+       }
 
        /* prevent write sources from being created */
-       
+
        in_set_state = true;
-       
+
        if ((prop = node.property ("name")) != 0) {
                _name = prop->value();
-       } 
+       }
 
        if (deprecated_io_node) {
                if ((prop = deprecated_io_node->property ("id")) != 0) {
@@ -1816,31 +1810,20 @@ AudioDiskstream::set_state (const XMLNode& node)
        if ((prop = node.property ("channels")) != 0) {
                nchans = atoi (prop->value().c_str());
        }
-       
+
        // create necessary extra channels
        // we are always constructed with one and we always need one
 
-       if (nchans > _n_channels) {
-
-               // we need to add new channel infos
-               //LockMonitor lm (state_lock, __LINE__, __FILE__);
+       _n_channels.set(DataType::AUDIO, channels.reader()->size());
 
-               int diff = nchans - channels.size();
-
-               for (int i=0; i < diff; ++i) {
-                       add_channel ();
-               }
+       if (nchans > _n_channels.n_audio()) {
 
-       } else if (nchans < _n_channels) {
+               add_channel (nchans - _n_channels.n_audio());
+               IO::PortCountChanged(_n_channels);
 
-               // we need to get rid of channels
-               //LockMonitor lm (state_lock, __LINE__, __FILE__);
+       } else if (nchans < _n_channels.n_audio()) {
 
-               int diff = channels.size() - nchans;
-               
-               for (int i = 0; i < diff; ++i) {
-                       remove_channel ();
-               }
+               remove_channel (_n_channels.n_audio() - nchans);
        }
 
        if ((prop = node.property ("playlist")) == 0) {
@@ -1849,7 +1832,7 @@ AudioDiskstream::set_state (const XMLNode& node)
 
        {
                bool had_playlist = (_playlist != 0);
-       
+
                if (find_and_use_playlist (prop->value())) {
                        return -1;
                }
@@ -1857,7 +1840,7 @@ AudioDiskstream::set_state (const XMLNode& node)
                if (!had_playlist) {
                        _playlist->set_orig_diskstream_id (_id);
                }
-               
+
                if (!destructive() && capture_pending_node) {
                        /* destructive streams have one and only one source per channel,
                           and so they never end up in pending capture in any useful
@@ -1876,19 +1859,15 @@ AudioDiskstream::set_state (const XMLNode& node)
                }
        }
 
-       _n_channels = channels.size();
-
        in_set_state = false;
 
        /* make sure this is clear before we do anything else */
 
        capturing_sources.clear ();
 
-       /* write sources are handled when we handle the input set 
+       /* write sources are handled when we handle the input set
           up of the IO that owns this DS (::non_realtime_input_change())
        */
-               
-       in_set_state = false;
 
        return 0;
 }
@@ -1896,67 +1875,75 @@ AudioDiskstream::set_state (const XMLNode& node)
 int
 AudioDiskstream::use_new_write_source (uint32_t n)
 {
+       boost::shared_ptr<ChannelList> c = channels.reader();
+
        if (!recordable()) {
                return 1;
        }
 
-       if (n >= channels.size()) {
+       if (n >= c->size()) {
                error << string_compose (_("AudioDiskstream: channel %1 out of range"), n) << endmsg;
                return -1;
        }
 
-       ChannelInfo &chan = channels[n];
-       
-       if (chan.write_source) {
-               chan.write_source->set_allow_remove_if_empty (true);
-               chan.write_source.reset ();
+       ChannelInfo* chan = (*c)[n];
+
+       if (chan->write_source) {
+               chan->write_source->done_with_peakfile_writes ();
+               chan->write_source->set_allow_remove_if_empty (true);
+               chan->write_source.reset ();
        }
 
        try {
-               if ((chan.write_source = _session.create_audio_source_for_session (*this, n, destructive())) == 0) {
+               if ((chan->write_source = _session.create_audio_source_for_session (*this, n, destructive())) == 0) {
                        throw failed_constructor();
                }
-       } 
+       }
 
        catch (failed_constructor &err) {
                error << string_compose (_("%1:%2 new capture file not initialized correctly"), _name, n) << endmsg;
-               chan.write_source.reset ();
+               chan->write_source.reset ();
                return -1;
        }
 
        /* do not remove destructive files even if they are empty */
 
-       chan.write_source->set_allow_remove_if_empty (!destructive());
+       chan->write_source->set_allow_remove_if_empty (!destructive());
+       
+       /* until we write, this file is considered removable */
+
+       chan->write_source->mark_for_remove ();
 
        return 0;
 }
 
 void
-AudioDiskstream::reset_write_sources (bool mark_write_complete, bool force)
+AudioDiskstream::reset_write_sources (bool mark_write_complete, bool /*force*/)
 {
        ChannelList::iterator chan;
+       boost::shared_ptr<ChannelList> c = channels.reader();
        uint32_t n;
 
-       if (!recordable()) {
+       if (!_session.writable() || !recordable()) {
                return;
        }
-       
+
        capturing_sources.clear ();
 
-       for (chan = channels.begin(), n = 0; chan != channels.end(); ++chan, ++n) {
+       for (chan = c->begin(), n = 0; chan != c->end(); ++chan, ++n) {
                if (!destructive()) {
 
-                       if ((*chan).write_source && mark_write_complete) {
-                               (*chan).write_source->mark_streaming_write_completed ();
+                       if ((*chan)->write_source && mark_write_complete) {
+                               (*chan)->write_source->mark_streaming_write_completed ();
                        }
                        use_new_write_source (n);
 
                        if (record_enabled()) {
-                               capturing_sources.push_back ((*chan).write_source);
+                               capturing_sources.push_back ((*chan)->write_source);
                        }
 
                } else {
-                       if ((*chan).write_source == 0) {
+                       if ((*chan)->write_source == 0) {
                                use_new_write_source (n);
                        }
                }
@@ -1978,11 +1965,12 @@ int
 AudioDiskstream::rename_write_sources ()
 {
        ChannelList::iterator chan;
+       boost::shared_ptr<ChannelList> c = channels.reader();
        uint32_t n;
 
-       for (chan = channels.begin(), n = 0; chan != channels.end(); ++chan, ++n) {
-               if ((*chan).write_source != 0) {
-                       (*chan).write_source->set_name (_name, destructive());
+       for (chan = c->begin(), n = 0; chan != c->end(); ++chan, ++n) {
+               if ((*chan)->write_source != 0) {
+                       (*chan)->write_source->set_source_name (_name, destructive());
                        /* XXX what to do if one of them fails ? */
                }
        }
@@ -1991,14 +1979,16 @@ AudioDiskstream::rename_write_sources ()
 }
 
 void
-AudioDiskstream::set_block_size (nframes_t nframes)
+AudioDiskstream::set_block_size (nframes_t /*nframes*/)
 {
        if (_session.get_block_size() > speed_buffer_size) {
                speed_buffer_size = _session.get_block_size();
+               boost::shared_ptr<ChannelList> c = channels.reader();
 
-               for (ChannelList::iterator chan = channels.begin(); chan != channels.end(); ++chan) {
-                       if ((*chan).speed_buffer) delete [] (*chan).speed_buffer;
-                       (*chan).speed_buffer = new Sample[speed_buffer_size];
+               for (ChannelList::iterator chan = c->begin(); chan != c->end(); ++chan) {
+                       if ((*chan)->speed_buffer)
+                               delete [] (*chan)->speed_buffer;
+                       (*chan)->speed_buffer = new Sample[speed_buffer_size];
                }
        }
        allocate_temporary_buffers ();
@@ -2009,7 +1999,7 @@ AudioDiskstream::allocate_temporary_buffers ()
 {
        /* make sure the wrap buffer is at least large enough to deal
           with the speeds up to 1.2, to allow for micro-variation
-          when slaving to MTC, SMPTE etc.
+          when slaving to MTC, Timecode etc.
        */
 
        double sp = max (fabsf (_actual_speed), 1.2f);
@@ -2017,11 +2007,15 @@ AudioDiskstream::allocate_temporary_buffers ()
 
        if (required_wrap_size > wrap_buffer_size) {
 
-               for (ChannelList::iterator chan = channels.begin(); chan != channels.end(); ++chan) {
-                       if ((*chan).playback_wrap_buffer) delete [] (*chan).playback_wrap_buffer;
-                       (*chan).playback_wrap_buffer = new Sample[required_wrap_size];  
-                       if ((*chan).capture_wrap_buffer) delete [] (*chan).capture_wrap_buffer;
-                       (*chan).capture_wrap_buffer = new Sample[required_wrap_size];   
+               boost::shared_ptr<ChannelList> c = channels.reader();
+
+               for (ChannelList::iterator chan = c->begin(); chan != c->end(); ++chan) {
+                       if ((*chan)->playback_wrap_buffer)
+                               delete [] (*chan)->playback_wrap_buffer;
+                       (*chan)->playback_wrap_buffer = new Sample[required_wrap_size];
+                       if ((*chan)->capture_wrap_buffer)
+                               delete [] (*chan)->capture_wrap_buffer;
+                       (*chan)->capture_wrap_buffer = new Sample[required_wrap_size];
                }
 
                wrap_buffer_size = required_wrap_size;
@@ -2031,10 +2025,12 @@ AudioDiskstream::allocate_temporary_buffers ()
 void
 AudioDiskstream::monitor_input (bool yn)
 {
-       for (ChannelList::iterator chan = channels.begin(); chan != channels.end(); ++chan) {
-               
-               if ((*chan).source) {
-                       (*chan).source->ensure_monitor_input (yn);
+       boost::shared_ptr<ChannelList> c = channels.reader();
+
+       for (ChannelList::iterator chan = c->begin(); chan != c->end(); ++chan) {
+
+               if ((*chan)->source) {
+                       (*chan)->source->ensure_monitor_input (yn);
                }
        }
 }
@@ -2049,9 +2045,11 @@ AudioDiskstream::set_align_style_from_io ()
        }
 
        get_input_sources ();
-       
-       for (ChannelList::iterator chan = channels.begin(); chan != channels.end(); ++chan) {
-               if ((*chan).source && (*chan).source->flags() & JackPortIsPhysical) {
+
+       boost::shared_ptr<ChannelList> c = channels.reader();
+
+       for (ChannelList::iterator chan = c->begin(); chan != c->end(); ++chan) {
+               if ((*chan)->source && (*chan)->source->flags() & JackPortIsPhysical) {
                        have_physical = true;
                        break;
                }
@@ -2065,55 +2063,68 @@ AudioDiskstream::set_align_style_from_io ()
 }
 
 int
-AudioDiskstream::add_channel ()
+AudioDiskstream::add_channel_to (boost::shared_ptr<ChannelList> c, uint32_t how_many)
 {
-       /* XXX need to take lock??? */
+       while (how_many--) {
+               c->push_back (new ChannelInfo(_session.butler()->audio_diskstream_buffer_size(), speed_buffer_size, wrap_buffer_size));
+               interpolation.add_channel_to (_session.butler()->audio_diskstream_buffer_size(), speed_buffer_size);
+       }
 
-       /* this copies the ChannelInfo, which currently has no buffers. kind
-          of pointless really, but we want the channels list to contain
-          actual objects, not pointers to objects. mostly for convenience,
-          which isn't much in evidence.
-       */
+       _n_channels.set(DataType::AUDIO, c->size());
 
-       channels.push_back (ChannelInfo());
+       return 0;
+}
 
-       /* now allocate the buffers */
+int
+AudioDiskstream::add_channel (uint32_t how_many)
+{
+       RCUWriter<ChannelList> writer (channels);
+       boost::shared_ptr<ChannelList> c = writer.get_copy();
 
-       channels.back().init (_session.diskstream_buffer_size(), 
-                             speed_buffer_size,
-                             wrap_buffer_size);
+       return add_channel_to (c, how_many);
+}
 
-       _n_channels = channels.size();
+int
+AudioDiskstream::remove_channel_from (boost::shared_ptr<ChannelList> c, uint32_t how_many)
+{
+       while (how_many-- && !c->empty()) {
+               // FIXME: crash (thread safe with RCU?)
+               // memory leak, when disabled.... :(
+               //delete c->back();
+               c->pop_back();
+               interpolation.remove_channel_from ();
+       }
+
+       _n_channels.set(DataType::AUDIO, c->size());
 
        return 0;
 }
 
 int
-AudioDiskstream::remove_channel ()
+AudioDiskstream::remove_channel (uint32_t how_many)
 {
-       if (channels.size() > 1) {
-               /* XXX need to take lock??? */
-               channels.back().release ();
-               channels.pop_back();
-               _n_channels = channels.size();
-               return 0;
-       }
+       RCUWriter<ChannelList> writer (channels);
+       boost::shared_ptr<ChannelList> c = writer.get_copy();
 
-       return -1;
+       return remove_channel_from (c, how_many);
 }
 
 float
 AudioDiskstream::playback_buffer_load () const
 {
-       return (float) ((double) channels.front().playback_buf->read_space()/
-                       (double) channels.front().playback_buf->bufsize());
+       boost::shared_ptr<ChannelList> c = channels.reader();
+
+       return (float) ((double) c->front()->playback_buf->read_space()/
+                       (double) c->front()->playback_buf->bufsize());
 }
 
 float
 AudioDiskstream::capture_buffer_load () const
 {
-       return (float) ((double) channels.front().capture_buf->write_space()/
-                       (double) channels.front().capture_buf->bufsize());
+       boost::shared_ptr<ChannelList> c = channels.reader();
+
+       return (float) ((double) c->front()->capture_buf->write_space()/
+                       (double) c->front()->capture_buf->bufsize());
 }
 
 int
@@ -2142,8 +2153,16 @@ AudioDiskstream::use_pending_capture_data (XMLNode& node)
                                continue;
                        }
 
+                       // This protects sessions from errant CapturingSources in stored sessions
+                       struct stat sbuf;
+                       if (stat (prop->value().c_str(), &sbuf)) {
+                               continue;
+                       }
+
                        try {
-                               fs = boost::dynamic_pointer_cast<AudioFileSource> (SourceFactory::createWritable (_session, prop->value(), false, _session.frame_rate()));
+                               fs = boost::dynamic_pointer_cast<AudioFileSource> (
+                                               SourceFactory::createWritable (DataType::AUDIO, _session,
+                                                               prop->value(), false, _session.frame_rate()));
                        }
 
                        catch (failed_constructor& err) {
@@ -2154,7 +2173,7 @@ AudioDiskstream::use_pending_capture_data (XMLNode& node)
                        }
 
                        pending_sources.push_back (fs);
-                       
+
                        if (first_fs == 0) {
                                first_fs = fs;
                        }
@@ -2168,38 +2187,41 @@ AudioDiskstream::use_pending_capture_data (XMLNode& node)
                return 1;
        }
 
-       if (pending_sources.size() != _n_channels) {
+       if (pending_sources.size() != _n_channels.n_audio()) {
                error << string_compose (_("%1: incorrect number of pending sources listed - ignoring them all"), _name)
                      << endmsg;
                return -1;
        }
 
        boost::shared_ptr<AudioRegion> region;
-       
+
        try {
-               region = boost::dynamic_pointer_cast<AudioRegion> (RegionFactory::create (pending_sources, 0, first_fs->length(),
-                                                                                         region_name_from_path (first_fs->name(), true), 
-                                                                                         0, AudioRegion::Flag (AudioRegion::DefaultFlags|AudioRegion::Automatic|AudioRegion::WholeFile)));
+               region = boost::dynamic_pointer_cast<AudioRegion> (RegionFactory::create (
+                               pending_sources, 0, first_fs->length(first_fs->timeline_position()),
+                               region_name_from_path (first_fs->name(), true), 0,
+                               Region::Flag (Region::DefaultFlags|Region::Automatic|Region::WholeFile)));
                region->special_set_position (0);
        }
 
        catch (failed_constructor& err) {
-               error << string_compose (_("%1: cannot create whole-file region from pending capture sources"),
-                                 _name)
-                     << endmsg;
-               
+               error << string_compose (
+                               _("%1: cannot create whole-file region from pending capture sources"),
+                               _name) << endmsg;
+
                return -1;
        }
 
        try {
-               region = boost::dynamic_pointer_cast<AudioRegion> (RegionFactory::create (pending_sources, 0, first_fs->length(), region_name_from_path (first_fs->name(), true)));
+               region = boost::dynamic_pointer_cast<AudioRegion> (RegionFactory::create (
+                               pending_sources, 0, first_fs->length(first_fs->timeline_position()),
+                               region_name_from_path (first_fs->name(), true)));
        }
 
        catch (failed_constructor& err) {
                error << string_compose (_("%1: cannot create region from pending capture sources"),
                                  _name)
                      << endmsg;
-               
+
                return -1;
        }
 
@@ -2208,16 +2230,31 @@ AudioDiskstream::use_pending_capture_data (XMLNode& node)
        return 0;
 }
 
+int
+AudioDiskstream::set_non_layered (bool yn)
+{
+       if (yn != non_layered()) {
+
+               if (yn) {
+                       _flags = Flag (_flags | NonLayered);
+               } else {
+                       _flags = Flag (_flags & ~NonLayered);
+               }
+       }
+
+       return 0;
+}
+
 int
 AudioDiskstream::set_destructive (bool yn)
 {
        bool bounce_ignored;
 
        if (yn != destructive()) {
-               
+
                if (yn) {
                        /* requestor should already have checked this and
-                          bounced if necessary and desired 
+                          bounced if necessary and desired
                        */
                        if (!can_become_destructive (bounce_ignored)) {
                                return -1;
@@ -2252,7 +2289,7 @@ AudioDiskstream::can_become_destructive (bool& requires_bounce) const
        assert (first);
 
        /* do the source(s) for the region cover the session start position ? */
-       
+
        if (first->position() != _session.current_start_frame()) {
                if (first->start() > _session.current_start_frame()) {
                        requires_bounce = true;
@@ -2266,8 +2303,8 @@ AudioDiskstream::can_become_destructive (bool& requires_bounce) const
 
        assert (afirst);
 
-       if (afirst->source()->used() > 1) {
-               requires_bounce = true; 
+       if (_session.playlists->source_use_count (afirst->source()) > 1) {
+               requires_bounce = true;
                return false;
        }
 
@@ -2275,36 +2312,26 @@ AudioDiskstream::can_become_destructive (bool& requires_bounce) const
        return true;
 }
 
-AudioDiskstream::ChannelInfo::ChannelInfo ()
+AudioDiskstream::ChannelInfo::ChannelInfo (nframes_t bufsize, nframes_t speed_size, nframes_t wrap_size)
 {
-       playback_wrap_buffer = 0;
-       capture_wrap_buffer = 0;
-       speed_buffer = 0;
        peak_power = 0.0f;
        source = 0;
        current_capture_buffer = 0;
        current_playback_buffer = 0;
        curr_capture_cnt = 0;
-       playback_buf = 0;
-       capture_buf = 0;
-       capture_transition_buf = 0;
-}
 
-void
-AudioDiskstream::ChannelInfo::init (nframes_t bufsize, nframes_t speed_size, nframes_t wrap_size)
-{
        speed_buffer = new Sample[speed_size];
        playback_wrap_buffer = new Sample[wrap_size];
        capture_wrap_buffer = new Sample[wrap_size];
 
        playback_buf = new RingBufferNPT<Sample> (bufsize);
        capture_buf = new RingBufferNPT<Sample> (bufsize);
-       capture_transition_buf = new RingBufferNPT<CaptureTransition> (128);
-       
+       capture_transition_buf = new RingBufferNPT<CaptureTransition> (256);
+
        /* touch the ringbuffer buffers, which will cause
           them to be mapped into locked physical RAM if
           we're running with mlockall(). this doesn't do
-          much if we're not.  
+          much if we're not.
        */
 
        memset (playback_buf->buffer(), 0, sizeof (Sample) * playback_buf->bufsize());
@@ -2313,43 +2340,26 @@ AudioDiskstream::ChannelInfo::init (nframes_t bufsize, nframes_t speed_size, nfr
 }
 
 AudioDiskstream::ChannelInfo::~ChannelInfo ()
-{
-}
-
-void
-AudioDiskstream::ChannelInfo::release ()
 {
        if (write_source) {
                write_source.reset ();
        }
-               
-       if (speed_buffer) {
-               delete [] speed_buffer;
-               speed_buffer = 0;
-       }
 
-       if (playback_wrap_buffer) {
-               delete [] playback_wrap_buffer;
-               playback_wrap_buffer = 0;
-       }
+       delete [] speed_buffer;
+       speed_buffer = 0;
 
-       if (capture_wrap_buffer) {
-               delete [] capture_wrap_buffer;
-               capture_wrap_buffer = 0;
-       }
-       
-       if (playback_buf) {
-               delete playback_buf;
-               playback_buf = 0;
-       }
+       delete [] playback_wrap_buffer;
+       playback_wrap_buffer = 0;
 
-       if (capture_buf) {
-               delete capture_buf;
-               capture_buf = 0;
-       }
+       delete [] capture_wrap_buffer;
+       capture_wrap_buffer = 0;
 
-       if (capture_transition_buf) {
-               delete capture_transition_buf;
-               capture_transition_buf = 0;
-       }
+       delete playback_buf;
+       playback_buf = 0;
+
+       delete capture_buf;
+       capture_buf = 0;
+
+       delete capture_transition_buf;
+       capture_transition_buf = 0;
 }