Fixes for GCC 4.3.
[ardour.git] / libs / ardour / audio_diskstream.cc
index f80e03b41faef31326f85ebcaf81882607129545..59e6007a6dafc138fc06f0037f24a1a7dd5a5642 100644 (file)
 #include <sys/mman.h>
 
 #include <pbd/error.h>
-#include <pbd/basename.h>
 #include <glibmm/thread.h>
 #include <pbd/xml++.h>
 #include <pbd/memento_command.h>
 #include <pbd/enumwriter.h>
+#include <pbd/stacktrace.h>
 
 #include <ardour/ardour.h>
 #include <ardour/audioengine.h>
+#include <ardour/analyser.h>
 #include <ardour/audio_diskstream.h>
 #include <ardour/utils.h>
 #include <ardour/configuration.h>
@@ -49,6 +50,7 @@
 #include <ardour/playlist_factory.h>
 #include <ardour/cycle_timer.h>
 #include <ardour/audioregion.h>
+#include <ardour/audio_port.h>
 #include <ardour/source_factory.h>
 
 #include "i18n.h"
@@ -65,6 +67,7 @@ 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 */
 
@@ -79,6 +82,7 @@ AudioDiskstream::AudioDiskstream (Session &sess, const string &name, Diskstream:
 AudioDiskstream::AudioDiskstream (Session& sess, const XMLNode& node)
        : Diskstream(sess, node)
        , deprecated_io_node(NULL)
+       , channels (new ChannelList)
 {
        in_set_state = true;
        init (Recordable);
@@ -108,8 +112,8 @@ 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 ()
@@ -117,16 +121,17 @@ AudioDiskstream::~AudioDiskstream ()
        notify_callbacks ();
 
        {
-               /* don't be holding this lock as we exit the destructor, glib will wince
-                  visibly since the mutex gets destroyed before we release it.
-               */
-
-               Glib::Mutex::Lock lm (state_lock);
-               for (ChannelList::iterator chan = channels.begin(); chan != channels.end(); ++chan) {
-                       (*chan).release ();
+               RCUWriter<ChannelList> writer (channels);
+               boost::shared_ptr<ChannelList> c = writer.get_copy();
+               
+               for (ChannelList::iterator chan = c->begin(); chan != c->end(); ++chan) {
+                       delete *chan;
                }
-               channels.clear();
+
+               c->clear();
        }
+
+       channels.flush ();
 }
 
 void
@@ -152,37 +157,26 @@ 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) {
-
-                       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 ();
-                               }
+               {
+                       RCUWriter<ChannelList> writer (channels);
+                       boost::shared_ptr<ChannelList> c = writer.get_copy();
+                       
+                       _n_channels.set(DataType::AUDIO, c->size());
+                       
+                       if (_io->n_inputs().n_audio() > _n_channels.n_audio()) {
+                               add_channel_to (c, _io->n_inputs().n_audio() - _n_channels.n_audio());
+                       } else if (_io->n_inputs().n_audio() < _n_channels.n_audio()) {
+                               remove_channel_from (c, _n_channels.n_audio() - _io->n_inputs().n_audio());
                        }
-               } 
-
+               }
+               
                get_input_sources ();
                set_capture_offset ();
                
@@ -192,10 +186,12 @@ AudioDiskstream::non_realtime_input_change ()
                } else {
                        set_align_style_from_io ();
                }
-
+               
                input_change_pending = NoChange;
-       }
 
+               /* implicit unlock */
+       }
+       
        /* reset capture files */
 
        reset_write_sources (false);
@@ -212,27 +208,27 @@ AudioDiskstream::non_realtime_input_change ()
 void
 AudioDiskstream::get_input_sources ()
 {
-       uint32_t ni = _io->n_inputs();
-       
-       for (uint32_t n = 0; n < ni; ++n) {
+       boost::shared_ptr<ChannelList> c = channels.reader();
+
+       uint32_t n;
+       ChannelList::iterator chan;
+       uint32_t ni = _io->n_inputs().n_audio();
+       vector<string> connections;
+
+       for (n = 0, chan = c->begin(); chan != c->end() && n < ni; ++chan, ++n) {
                
-               const char **connections = _io->input(n)->get_connections ();
-               ChannelInfo& chan = channels[n];
+               connections.clear ();
+
+               if (_io->input(n)->get_connections (connections) == 0) {
                
-               if (connections == 0 || connections[0] == 0) {
-                       
-                       if (chan.source) {
+                       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]) );
                }
        }
 }              
@@ -243,7 +239,7 @@ 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));
+               playlist = boost::dynamic_pointer_cast<AudioPlaylist> (PlaylistFactory::create (DataType::AUDIO, _session, name));
        }
 
        if (!playlist) {
@@ -269,7 +265,7 @@ AudioDiskstream::use_new_playlist ()
 {
        string newname;
        boost::shared_ptr<AudioPlaylist> playlist;
-
+       
        if (!in_set_state && destructive()) {
                return 0;
        }
@@ -280,7 +276,7 @@ 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);
@@ -321,9 +317,10 @@ void
 AudioDiskstream::setup_destructive_playlist ()
 {
        SourceList srcs;
-
-       for (ChannelList::iterator chan = channels.begin(); chan != channels.end(); ++chan) {
-               srcs.push_back ((*chan).write_source);
+       boost::shared_ptr<ChannelList> c = channels.reader();
+       
+       for (ChannelList::iterator chan = c->begin(); chan != c->end(); ++chan) {
+               srcs.push_back ((*chan)->write_source);
        }
 
        /* a single full-sized region */
@@ -360,15 +357,16 @@ 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 */
@@ -400,8 +398,8 @@ AudioDiskstream::check_record_status (nframes_t transport_frame, nframes_t nfram
 
        /* 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()))) {
+       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 */
 
@@ -463,16 +461,17 @@ AudioDiskstream::check_record_status (nframes_t transport_frame, nframes_t nfram
                        
                }
 
-               if (_flags & Recordable) {
-                       for (ChannelList::iterator chan = channels.begin(); chan != channels.end(); ++chan) {
+               if (recordable() && destructive()) {
+                       boost::shared_ptr<ChannelList> c = channels.reader();
+                       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 = CaptureStart;
                                        transvec.buf[0]->capture_val = capture_start_frame;
-                                       (*chan).capture_transition_buf->increment_write_ptr(1);
+                                       (*chan)->capture_transition_buf->increment_write_ptr(1);
                                }
                                else {
                                        // bad!
@@ -502,7 +501,8 @@ int
 AudioDiskstream::process (nframes_t transport_frame, nframes_t nframes, nframes_t offset, 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 +522,13 @@ AudioDiskstream::process (nframes_t transport_frame, nframes_t nframes, nframes_
                return 0;
        }
 
+       commit_should_unlock = false;
+
+       if (!_io->active()) {
+               _processed = true;
+               return 0;
+       }
+
        check_record_status (transport_frame, nframes, can_record);
 
        nominally_recording = (can_record && re);
@@ -539,18 +546,23 @@ AudioDiskstream::process (nframes_t transport_frame, nframes_t nframes, nframes_
        // If we can't take the state lock return.
        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;
                
+               // 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; 
+               }
+
                ot = coverage (first_recordable_frame, last_recordable_frame, transport_frame, transport_frame + nframes);
 
                switch (ot) {
@@ -588,7 +600,7 @@ AudioDiskstream::process (nframes_t transport_frame, nframes_t nframes, nframes_
                        /*    |--------|    recrange
                             --------------  transrange
                        */
-                       rec_nframes = last_recordable_frame - last_recordable_frame;
+                       rec_nframes = last_recordable_frame - first_recordable_frame;
                        rec_offset = first_recordable_frame - transport_frame;
                        break;
                }
@@ -606,47 +618,62 @@ 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) {
+               uint32_t limit = _io->n_inputs ().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& chan (*c);
-               
-                       chan.capture_buf->get_write_vector (&chan.capture_vector);
+                       ChannelInfo* chaninfo (*chan);
+
+                       chaninfo->capture_buf->get_write_vector (&chaninfo->capture_vector);
 
-                       if (rec_nframes <= chan.capture_vector.len[0]) {
+                       if (rec_nframes <= chaninfo->capture_vector.len[0]) {
                                
-                               chan.current_capture_buffer = chan.capture_vector.buf[0];
+                               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_input(n);
+                               assert(ap);
+                               assert(rec_nframes <= ap->get_audio_buffer().capacity());
+                               memcpy (chaninfo->current_capture_buffer, ap->get_audio_buffer().data(rec_nframes, offset + 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_input(n);
+                               assert(ap);
+
+                               Sample* buf = ap->get_audio_buffer().data(nframes, offset);
+                               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));
+                               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));
                                
-                               chan.current_capture_buffer = chan.capture_wrap_buffer;
+                               chaninfo->current_capture_buffer = chaninfo->capture_wrap_buffer;
                        }
                }
 
        } else {
 
                if (was_recording) {
-                       finish_capture (rec_monitors_input);
+                       finish_capture (rec_monitors_input, c);
                }
 
        }
@@ -657,8 +684,8 @@ AudioDiskstream::process (nframes_t transport_frame, nframes_t nframes, nframes_
 
                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 +707,8 @@ 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;
@@ -705,35 +732,36 @@ AudioDiskstream::process (nframes_t transport_frame, nframes_t nframes, nframes_
                        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;                  
 
-               for (c = channels.begin(); c != channels.end(); ++c, ++n) {
-               
-                       ChannelInfo& chan (*c);
+               for (chan = c->begin(); chan != c->end(); ++chan, ++n) {
+                       
+                       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 << "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));
+                                       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));
                                        
-                                       chan.current_playback_buffer = chan.playback_wrap_buffer;
+                                       chaninfo->current_playback_buffer = chaninfo->playback_wrap_buffer;
                                }
                        }
                } 
@@ -741,15 +769,22 @@ AudioDiskstream::process (nframes_t transport_frame, nframes_t nframes, nframes_
                if (rec_nframes == 0 && _actual_speed != 1.0f && _actual_speed != -1.0f) {
                        
                        uint64_t phase = last_phase;
+                       int64_t phi_delta;
                        nframes_t i = 0;
 
                        // Linearly interpolate into the alt buffer
                        // using 40.24 fixp maths (swh)
 
-                       for (c = channels.begin(); c != channels.end(); ++c) {
+                       if (phi != target_phi) {
+                               phi_delta = ((int64_t)(target_phi - phi)) / nframes;
+                       } else {
+                               phi_delta = 0;
+                       }
+
+                       for (chan = c->begin(); chan != c->end(); ++chan) {
 
                                float fr;
-                               ChannelInfo& chan (*c);
+                               ChannelInfo* chaninfo (*chan);
 
                                i = 0;
                                phase = last_phase;
@@ -757,22 +792,24 @@ AudioDiskstream::process (nframes_t transport_frame, nframes_t nframes, nframes_
                                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->speed_buffer[outsample] = 
+                                               chaninfo->current_playback_buffer[i] * (1.0f - fr) +
+                                               chaninfo->current_playback_buffer[i+1] * fr;
+                                       phase += phi + phi_delta;
                                }
                                
-                               chan.current_playback_buffer = chan.speed_buffer;
+                               chaninfo->current_playback_buffer = chaninfo->speed_buffer;
                        }
 
-                       playback_distance = i + 1;
+                       playback_distance = i; // + 1;
                        last_phase = (phase & 0xFFFFFF);
 
                } else {
                        playback_distance = nframes;
                }
 
+               phi = target_phi;
+
        }
 
        ret = 0;
@@ -786,6 +823,7 @@ AudioDiskstream::process (nframes_t transport_frame, nframes_t nframes, nframes_
                   be called. unlock the state lock.
                */
                
+               commit_should_unlock = false;
                state_lock.unlock();
        } 
 
@@ -797,18 +835,23 @@ AudioDiskstream::commit (nframes_t nframes)
 {
        bool need_butler = false;
 
+       if (!_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);
                }
        }
        
@@ -818,13 +861,23 @@ AudioDiskstream::commit (nframes_t nframes)
        }
        
        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;
 
@@ -839,12 +892,13 @@ AudioDiskstream::set_pending_overwrite (bool yn)
        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 ()
 {
+       boost::shared_ptr<ChannelList> c = channels.reader();
        Sample* mixdown_buffer;
        float* gain_buffer;
        int ret = -1;
@@ -853,7 +907,7 @@ AudioDiskstream::overwrite_existing_buffers ()
        overwrite_queued = false;
 
        /* assume all are the same size */
-       nframes_t size = channels[0].playback_buf->bufsize();
+       nframes_t size = c->front()->playback_buf->bufsize();
        
        mixdown_buffer = new Sample[size];
        gain_buffer = new float[size];
@@ -864,7 +918,7 @@ AudioDiskstream::overwrite_existing_buffers ()
        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;
@@ -882,7 +936,7 @@ AudioDiskstream::overwrite_existing_buffers ()
                
                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;
@@ -892,7 +946,7 @@ AudioDiskstream::overwrite_existing_buffers ()
 
                        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;
@@ -913,25 +967,27 @@ AudioDiskstream::overwrite_existing_buffers ()
 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();
 
-       for (n = 0, chan = channels.begin(); chan != channels.end(); ++chan, ++n) {
-               (*chan).playback_buf->reset ();
-               (*chan).capture_buf->reset ();
+       Glib::Mutex::Lock lm (state_lock);
+       
+       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()) {
                disengage_record_enable ();
        }
-
+       
        playback_sample = frame;
        file_frame = frame;
-
+       
        if (complete_refill) {
                while ((ret = do_refill_with_alloc ()) > 0) ;
        } else {
@@ -945,9 +1001,10 @@ 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;
                } 
        }
@@ -958,9 +1015,10 @@ 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;
@@ -971,7 +1029,7 @@ AudioDiskstream::internal_playback_seek (nframes_t distance)
 
 int
 AudioDiskstream::read (Sample* buf, Sample* mixdown_buffer, float* gain_buffer, nframes_t& start, nframes_t cnt, 
-                 ChannelInfo& channel_info, int channel, bool reversed)
+                      ChannelInfo* channel_info, int channel, bool reversed)
 {
        nframes_t this_read = 0;
        bool reloop = false;
@@ -1066,7 +1124,7 @@ 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];
@@ -1090,8 +1148,13 @@ 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);
 
@@ -1100,8 +1163,7 @@ AudioDiskstream::_do_refill (Sample* mixdown_buffer, float* gain_buffer)
        vector.buf[1] = 0;
        vector.len[1] = 0;
 
-       channels.front().playback_buf->get_write_vector (&vector);
-
+       c->front()->playback_buf->get_write_vector (&vector);
        
        if ((total_space = vector.len[0] + vector.len[1]) == 0) {
                return 0;
@@ -1132,7 +1194,7 @@ AudioDiskstream::_do_refill (Sample* mixdown_buffer, float* gain_buffer)
           work with.
        */
        
-       if (_slaved && total_space < (channels.front().playback_buf->bufsize() / 2)) {
+       if (_slaved && total_space < (c->front()->playback_buf->bufsize() / 2)) {
                return 0;
        }
 
@@ -1146,15 +1208,15 @@ 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) {
+                       for (chan_n = 0, i = c->begin(); i != c->end(); ++i, ++chan_n) {
                                        
-                               ChannelInfo& chan (*i);
-                               chan.playback_buf->get_write_vector (&vector);
+                               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;
                }
@@ -1180,15 +1242,15 @@ AudioDiskstream::_do_refill (Sample* mixdown_buffer, float* gain_buffer)
 
                        /* at end: nothing to do but fill with silence */
                        
-                       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);
-                               chan.playback_buf->get_write_vector (&vector);
+                               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;
                }
@@ -1207,14 +1269,14 @@ AudioDiskstream::_do_refill (Sample* mixdown_buffer, float* gain_buffer)
        
        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) {
                        
@@ -1257,7 +1319,7 @@ 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;
                }
 
@@ -1274,7 +1336,7 @@ 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);
                }
 
                if (zero_fill) {
@@ -1316,9 +1378,10 @@ AudioDiskstream::do_flush (Session::RunContext context, bool force_flush)
        vector.buf[0] = 0;
        vector.buf[1] = 0;
 
-       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).capture_buf->get_read_vector (&vector);
+               (*chan)->capture_buf->get_read_vector (&vector);
 
                total = vector.len[0] + vector.len[1];
 
@@ -1347,7 +1410,7 @@ AudioDiskstream::do_flush (Session::RunContext context, bool force_flush)
                // 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;
@@ -1358,8 +1421,8 @@ AudioDiskstream::do_flush (Session::RunContext context, bool force_flush)
                                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;
                                }
@@ -1367,17 +1430,17 @@ 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;
@@ -1392,17 +1455,17 @@ 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()) {
                
@@ -1413,15 +1476,15 @@ AudioDiskstream::do_flush (Session::RunContext context, bool force_flush)
                        
                        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();
+                       _write_data_count += (*chan)->write_source->write_data_count();
        
-                       (*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;
                }
        }
 
@@ -1441,10 +1504,11 @@ AudioDiskstream::transport_stopped (struct tm& when, time_t twhen, bool abort_ca
        SourceList::iterator src;
        ChannelList::iterator chan;
        vector<CaptureInfo*>::iterator ci;
+       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 
           to flush remaining data to disk.
@@ -1476,13 +1540,13 @@ AudioDiskstream::transport_stopped (struct tm& when, time_t twhen, bool abort_ca
                        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 */
@@ -1497,15 +1561,18 @@ 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);
+                       }
                }
        }
 
@@ -1524,7 +1591,7 @@ AudioDiskstream::transport_stopped (struct tm& when, time_t twhen, bool abort_ca
        } 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
@@ -1533,7 +1600,7 @@ AudioDiskstream::transport_stopped (struct tm& when, time_t twhen, bool abort_ca
                */
                
                try {
-                       boost::shared_ptr<Region> rx (RegionFactory::create (srcs, channels[0].write_source->last_capture_start_frame(), total_capture, 
+                       boost::shared_ptr<Region> rx (RegionFactory::create (srcs, c->front()->write_source->last_capture_start_frame(), total_capture, 
                                                                             whole_file_region_name,
                                                                             0, AudioRegion::Flag (AudioRegion::DefaultFlags|AudioRegion::Automatic|AudioRegion::WholeFile)));
 
@@ -1551,10 +1618,10 @@ AudioDiskstream::transport_stopped (struct tm& when, time_t twhen, bool abort_ca
 
                // 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;
 
@@ -1584,7 +1651,7 @@ AudioDiskstream::transport_stopped (struct tm& when, time_t twhen, bool abort_ca
                }
 
                _playlist->thaw ();
-                XMLNode &after = _playlist->get_state();
+               XMLNode &after = _playlist->get_state();
                _session.add_command (new MementoCommand<Playlist>(*_playlist, &before, &after));
        }
 
@@ -1604,7 +1671,58 @@ 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;
        
@@ -1613,16 +1731,15 @@ AudioDiskstream::finish_capture (bool rec_monitors_input)
        }
 
        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!
@@ -1650,12 +1767,15 @@ 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_inputs().n_audio() == 0) {
                return;
        }
 
@@ -1665,7 +1785,7 @@ AudioDiskstream::set_record_enabled (bool yn)
                return;
        }
 
-       if (yn && channels[0].source == 0) {
+       if (yn && channels.reader()->front()->source == 0) {
 
                /* pick up connections not initiated *from* the IO object
                   we're associated with.
@@ -1690,23 +1810,26 @@ 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 (!(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 ();
                }
        }
 
@@ -1717,10 +1840,11 @@ void
 AudioDiskstream::disengage_record_enable ()
 {
        g_atomic_int_set (&_record_enabled, 0);
-       for (ChannelList::iterator chan = channels.begin(); chan != channels.end(); ++chan) {
-               if (Config->get_monitoring_model() == HardwareMonitoring) {
-                       if ((*chan).source) {
-                               (*chan).source->ensure_monitor_input (false);
+       boost::shared_ptr<ChannelList> c = channels.reader();
+       if (Config->get_monitoring_model() == HardwareMonitoring) {
+               for (ChannelList::iterator chan = c->begin(); chan != c->end(); ++chan) {
+                       if ((*chan)->source) {
+                               (*chan)->source->ensure_monitor_input (false);
                        }
                }
        }
@@ -1734,10 +1858,11 @@ 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());
@@ -1832,27 +1957,16 @@ AudioDiskstream::set_state (const XMLNode& node)
        // 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__);
-
-               int diff = nchans - channels.size();
-
-               for (int i=0; i < diff; ++i) {
-                       add_channel ();
-               }
+       _n_channels.set(DataType::AUDIO, channels.reader()->size());
+       
+       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) {
@@ -1888,8 +2002,6 @@ AudioDiskstream::set_state (const XMLNode& node)
                }
        }
 
-       _n_channels = channels.size();
-
        in_set_state = false;
 
        /* make sure this is clear before we do anything else */
@@ -1900,46 +2012,46 @@ AudioDiskstream::set_state (const XMLNode& node)
           up of the IO that owns this DS (::non_realtime_input_change())
        */
                
-       in_set_state = false;
-
        return 0;
 }
 
 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];
+       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 ();
+       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());
 
        return 0;
 }
@@ -1948,6 +2060,7 @@ void
 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()) {
@@ -1956,20 +2069,20 @@ AudioDiskstream::reset_write_sources (bool mark_write_complete, bool force)
        
        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);
                        }
                }
@@ -1991,11 +2104,12 @@ 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 ? */
                }
        }
@@ -2008,10 +2122,11 @@ 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 ();
@@ -2030,11 +2145,13 @@ 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;
@@ -2044,10 +2161,12 @@ AudioDiskstream::allocate_temporary_buffers ()
 void
 AudioDiskstream::monitor_input (bool yn)
 {
-       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) {
                
-               if ((*chan).source) {
-                       (*chan).source->ensure_monitor_input (yn);
+               if ((*chan)->source) {
+                       (*chan)->source->ensure_monitor_input (yn);
                }
        }
 }
@@ -2063,8 +2182,10 @@ 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;
                }
@@ -2078,55 +2199,64 @@ 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.diskstream_buffer_size(), speed_buffer_size, wrap_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()) {
+               delete c->back();
+               c->pop_back();
+       }
+
+       _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;
-       }
-
-       return -1;
+       RCUWriter<ChannelList> writer (channels);
+       boost::shared_ptr<ChannelList> c = writer.get_copy();
+       
+       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
@@ -2155,8 +2285,15 @@ 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) {
@@ -2181,7 +2318,7 @@ 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;
@@ -2288,31 +2425,21 @@ 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
@@ -2326,11 +2453,6 @@ AudioDiskstream::ChannelInfo::init (nframes_t bufsize, nframes_t speed_size, nfr
 }
 
 AudioDiskstream::ChannelInfo::~ChannelInfo ()
-{
-}
-
-void
-AudioDiskstream::ChannelInfo::release ()
 {
        if (write_source) {
                write_source.reset ();