Initial changes needed for building Mixbus (with MSVC) as version 5
[ardour.git] / libs / ardour / disk_reader.cc
index 10cf428c822c202b821abfc36ca8ae10b1477c42..375dda70759f0f4345e193223d07eb67b0c04fb5 100644 (file)
@@ -17,7 +17,9 @@
 
 */
 
-#include "pbd/i18n.h"
+#include <boost/smart_ptr/scoped_array.hpp>
+
+#include "pbd/enumwriter.h"
 #include "pbd/memento_command.h"
 
 #include "ardour/audioengine.h"
 #include "ardour/disk_reader.h"
 #include "ardour/midi_ring_buffer.h"
 #include "ardour/midi_playlist.h"
+#include "ardour/midi_track.h"
+#include "ardour/pannable.h"
 #include "ardour/playlist.h"
 #include "ardour/playlist_factory.h"
 #include "ardour/session.h"
 #include "ardour/session_playlists.h"
 
+#include "pbd/i18n.h"
+
 using namespace ARDOUR;
 using namespace PBD;
 using namespace std;
 
-ARDOUR::framecnt_t DiskReader::_chunk_frames = default_chunk_frames ();
+ARDOUR::samplecnt_t DiskReader::_chunk_samples = default_chunk_samples ();
+PBD::Signal0<void> DiskReader::Underrun;
+Sample* DiskReader::_mixdown_buffer = 0;
+gain_t* DiskReader::_gain_buffer = 0;
+samplecnt_t DiskReader::midi_readahead = 4096;
+bool DiskReader::_no_disk_output = false;
 
 DiskReader::DiskReader (Session& s, string const & str, DiskIOProcessor::Flag f)
        : DiskIOProcessor (s, str, f)
-       , _roll_delay (0)
-       , loop_location (0)
-       , overwrite_frame (0)
-        , overwrite_offset (0)
-        , _pending_overwrite (false)
-        , overwrite_queued (false)
-        , file_frame (0)
-        , playback_sample (0)
-       , _monitoring_choice (MonitorDisk)
-       , _need_butler (false)
-       , _gui_feed_buffer (AudioEngine::instance()->raw_buffer_size (DataType::MIDI))
-       , _frames_written_to_ringbuffer (0)
-       , _frames_read_from_ringbuffer (0)
+       , overwrite_sample (0)
+       , overwrite_offset (0)
+       , _pending_overwrite (false)
+       , overwrite_queued (false)
+       , _declick_gain (0)
 {
+       file_sample[DataType::AUDIO] = 0;
+       file_sample[DataType::MIDI] = 0;
 }
 
 DiskReader::~DiskReader ()
 {
-       DEBUG_TRACE (DEBUG::Destruction, string_compose ("DiskReader %1 deleted\n", _name));
-       Glib::Threads::Mutex::Lock lm (state_lock);
+       DEBUG_TRACE (DEBUG::Destruction, string_compose ("DiskReader %1 @ %2 deleted\n", _name, this));
 
        for (uint32_t n = 0; n < DataType::num_types; ++n) {
                if (_playlists[n]) {
                        _playlists[n]->release ();
                }
        }
+       delete _midi_buf;
+}
 
-       {
-               RCUWriter<ChannelList> writer (channels);
-               boost::shared_ptr<ChannelList> c = writer.get_copy();
-
-               for (ChannelList::iterator chan = c->begin(); chan != c->end(); ++chan) {
-                       delete *chan;
-               }
+void
+DiskReader::ReaderChannelInfo::resize (samplecnt_t bufsize)
+{
+       delete rbuf;
+       /* touch memory to lock it */
+       rbuf = new RingBufferNPT<Sample> (bufsize);
+       memset (rbuf->buffer(), 0, sizeof (Sample) * rbuf->bufsize());
+}
 
-               c->clear();
+int
+DiskReader::add_channel_to (boost::shared_ptr<ChannelList> c, uint32_t how_many)
+{
+       while (how_many--) {
+               c->push_back (new ReaderChannelInfo (_session.butler()->audio_diskstream_playback_buffer_size()));
+               DEBUG_TRACE (DEBUG::DiskIO, string_compose ("%1: new reader channel, write space = %2 read = %3\n",
+                                                           name(),
+                                                           c->back()->rbuf->write_space(),
+                                                           c->back()->rbuf->read_space()));
        }
 
-       channels.flush ();
-
-       delete _midi_buf;
+       return 0;
 }
 
 void
@@ -105,8 +118,8 @@ DiskReader::free_working_buffers()
        _gain_buffer          = 0;
 }
 
-framecnt_t
-DiskReader::default_chunk_frames()
+samplecnt_t
+DiskReader::default_chunk_samples()
 {
        return 65536;
 }
@@ -114,97 +127,34 @@ DiskReader::default_chunk_frames()
 bool
 DiskReader::set_name (string const & str)
 {
-       if (_name != str) {
-               for (uint32_t n = 0; n < DataType::num_types; ++n) {
-                       if (_playlists[n]) {
-                               _playlists[n]->set_name (str);
-                       }
-               }
-               SessionObject::set_name(str);
+       string my_name = X_("player:");
+       my_name += str;
+
+       if (_name != my_name) {
+               SessionObject::set_name (my_name);
        }
 
        return true;
 }
 
-void
-DiskReader::set_roll_delay (ARDOUR::framecnt_t nframes)
+XMLNode&
+DiskReader::state ()
 {
-       _roll_delay = nframes;
+       XMLNode& node (DiskIOProcessor::state ());
+       node.set_property(X_("type"), X_("diskreader"));
+       return node;
 }
 
 int
 DiskReader::set_state (const XMLNode& node, int version)
 {
-       XMLProperty const * prop;
-
        if (DiskIOProcessor::set_state (node, version)) {
                return -1;
        }
 
-       if ((prop = node.property ("audio-playlist")) == 0) {
-               return -1;
-       }
-
-       if (find_and_use_playlist (DataType::AUDIO, prop->value())) {
-               return -1;
-       }
-
-       if ((prop = node.property ("midi-playlist")) == 0) {
-               return -1;
-       }
-
-       if (find_and_use_playlist (DataType::MIDI, prop->value())) {
-               return -1;
-       }
-
        return 0;
 }
 
-/* Processor interface */
-
-bool
-DiskReader::configure_io (ChanCount in, ChanCount out)
-{
-       Glib::Threads::Mutex::Lock lm (state_lock);
-
-       RCUWriter<ChannelList> writer (channels);
-       boost::shared_ptr<ChannelList> c = writer.get_copy();
-
-       uint32_t n_audio = in.n_audio();
-
-       if (n_audio > c->size()) {
-               add_channel_to (c, n_audio - c->size());
-       } else if (n_audio < c->size()) {
-               remove_channel_from (c, c->size() - n_audio);
-       }
-
-       if (in.n_midi() > 0 && !_midi_buf) {
-               const size_t size = _session.butler()->midi_diskstream_buffer_size();
-               _midi_buf = new MidiRingBuffer<framepos_t>(size);
-               midi_interpolation.add_channel_to (0,0);
-       }
-
-       Processor::configure_io (in, out);
-
-       return true;
-}
-
-bool
-DiskReader::can_support_io_configuration (const ChanCount& in, ChanCount& out)
-{
-       if (in.n_midi() != 0 && in.n_midi() != 1) {
-               /* we only support zero or 1 MIDI stream */
-               return false;
-       }
-
-       if (in != out) {
-               /* currently no way to deliver different channels that we receive */
-               return false;
-       }
-
-       return true;
-}
-
 void
 DiskReader::realtime_handle_transport_stopped ()
 {
@@ -215,22 +165,6 @@ DiskReader::realtime_locate ()
 {
 }
 
-int
-DiskReader::set_loop (Location *location)
-{
-       if (location) {
-               if (location->start() >= location->end()) {
-                       error << string_compose(_("Location \"%1\" not valid for track loop (start >= end)"), location->name()) << endl;
-                       return -1;
-               }
-       }
-
-       loop_location = location;
-
-       LoopSet (location); /* EMIT SIGNAL */
-       return 0;
-}
-
 float
 DiskReader::buffer_load () const
 {
@@ -251,7 +185,7 @@ DiskReader::buffer_load () const
                return 1.0;
        }
 
-       PBD::RingBufferNPT<Sample> * b = c->front()->buf;
+       PBD::RingBufferNPT<Sample>* b = c->front()->rbuf;
        return (float) ((double) b->read_space() / (double) b->bufsize());
 }
 
@@ -265,87 +199,6 @@ DiskReader::adjust_buffering ()
        }
 }
 
-DiskReader::ChannelInfo::ChannelInfo (framecnt_t bufsize, framecnt_t speed_size, framecnt_t wrap_size)
-{
-       current_buffer = 0;
-
-       speed_buffer = new Sample[speed_size];
-       wrap_buffer = new Sample[wrap_size];
-
-       buf = new RingBufferNPT<Sample> (bufsize);
-
-       /* touch the ringbuffer buffer, 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.
-       */
-
-       memset (buf->buffer(), 0, sizeof (Sample) * buf->bufsize());
-}
-
-void
-DiskReader::ChannelInfo::resize (framecnt_t bufsize)
-{
-       delete buf;
-       buf = new RingBufferNPT<Sample> (bufsize);
-       memset (buf->buffer(), 0, sizeof (Sample) * buf->bufsize());
-}
-
-DiskReader::ChannelInfo::~ChannelInfo ()
-{
-       delete [] speed_buffer;
-       speed_buffer = 0;
-
-       delete [] wrap_buffer;
-       wrap_buffer = 0;
-
-       delete buf;
-       buf = 0;
-}
-
-int
-DiskReader::set_block_size (pframes_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 = c->begin(); chan != c->end(); ++chan) {
-                       delete [] (*chan)->speed_buffer;
-                       (*chan)->speed_buffer = new Sample[speed_buffer_size];
-               }
-       }
-       allocate_temporary_buffers ();
-       return 0;
-}
-
-void
-DiskReader::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, Timecode etc.
-       */
-
-       double const sp = max (fabs (_actual_speed), 1.2);
-       framecnt_t required_wrap_size = (framecnt_t) ceil (_session.get_block_size() * sp) + 2;
-
-       if (required_wrap_size > wrap_buffer_size) {
-
-               boost::shared_ptr<ChannelList> c = channels.reader();
-
-               for (ChannelList::iterator chan = c->begin(); chan != c->end(); ++chan) {
-                       if ((*chan)->wrap_buffer) {
-                               delete [] (*chan)->wrap_buffer;
-                       }
-                       (*chan)->wrap_buffer = new Sample[required_wrap_size];
-               }
-
-               wrap_buffer_size = required_wrap_size;
-       }
-}
-
-
 void
 DiskReader::playlist_changed (const PropertyChange&)
 {
@@ -356,75 +209,22 @@ void
 DiskReader::playlist_modified ()
 {
        if (!i_am_the_modifier && !overwrite_queued) {
-               // !!!! _session.request_overwrite_buffer (this);
+               _session.request_overwrite_buffer (_route);
                overwrite_queued = true;
        }
 }
 
-void
-DiskReader::playlist_deleted (boost::weak_ptr<Playlist> wpl)
-{
-       boost::shared_ptr<Playlist> pl (wpl.lock());
-
-       if (!pl) {
-               return;
-       }
-
-       for (uint32_t n = 0; n < DataType::num_types; ++n) {
-               if (pl == _playlists[n]) {
-
-                       /* this catches an ordering issue with session destruction. playlists
-                          are destroyed before disk readers. we have to invalidate any handles
-                          we have to the playlist.
-                       */
-                       _playlists[n].reset ();
-                       break;
-               }
-       }
-}
-
-boost::shared_ptr<AudioPlaylist>
-DiskReader::audio_playlist () const
-{
-       return boost::dynamic_pointer_cast<AudioPlaylist> (_playlists[DataType::AUDIO]);
-}
-
-boost::shared_ptr<MidiPlaylist>
-DiskReader::midi_playlist () const
-{
-       return boost::dynamic_pointer_cast<MidiPlaylist> (_playlists[DataType::MIDI]);
-}
-
 int
 DiskReader::use_playlist (DataType dt, boost::shared_ptr<Playlist> playlist)
 {
-        if (!playlist) {
-                return 0;
-        }
-
         bool prior_playlist = false;
 
-       {
-               Glib::Threads::Mutex::Lock lm (state_lock);
-
-               if (playlist == _playlists[dt]) {
-                       return 0;
-               }
-
-               playlist_connections.drop_connections ();
-
-               if (_playlists[dt]) {
-                       _playlists[dt]->release();
-                        prior_playlist = true;
-               }
-
-               _playlists[dt] = playlist;
-               playlist->use();
+        if (_playlists[dt]) {
+               prior_playlist = true;
+        }
 
-               playlist->ContentsChanged.connect_same_thread (playlist_connections, boost::bind (&DiskReader::playlist_modified, this));
-               playlist->LayeringChanged.connect_same_thread (playlist_connections, boost::bind (&DiskReader::playlist_modified, this));
-               playlist->DropReferences.connect_same_thread (playlist_connections, boost::bind (&DiskReader::playlist_deleted, this, boost::weak_ptr<Playlist>(playlist)));
-               playlist->RangesMoved.connect_same_thread (playlist_connections, boost::bind (&DiskReader::playlist_ranges_moved, this, _1, _2));
+        if (DiskIOProcessor::use_playlist (dt, playlist)) {
+               return -1;
        }
 
        /* don't do this if we've already asked for it *or* if we are setting up
@@ -432,366 +232,275 @@ DiskReader::use_playlist (DataType dt, boost::shared_ptr<Playlist> playlist)
           take care of the buffer refill.
        */
 
-       if (!overwrite_queued && prior_playlist) {
-               // !!! _session.request_overwrite_buffer (this);
+        if (!overwrite_queued && (prior_playlist || _session.loading())) {
+               _session.request_overwrite_buffer (_route);
                overwrite_queued = true;
        }
 
-       PlaylistChanged (dt); /* EMIT SIGNAL */
-       _session.set_dirty ();
-
        return 0;
 }
 
-int
-DiskReader::find_and_use_playlist (DataType dt, const string& name)
-{
-       boost::shared_ptr<Playlist> playlist;
-
-       if ((playlist = _session.playlists->by_name (name)) == 0) {
-               playlist = PlaylistFactory::create (dt, _session, name);
-       }
-
-       if (!playlist) {
-               error << string_compose(_("DiskReader: \"%1\" isn't an playlist"), name) << endmsg;
-               return -1;
-       }
-
-       return use_playlist (dt, playlist);
-}
-
-int
-DiskReader::use_new_playlist (DataType dt)
+void
+DiskReader::run (BufferSet& bufs, samplepos_t start_sample, samplepos_t end_sample,
+                 double speed, pframes_t nframes, bool result_required)
 {
-       string newname;
-       boost::shared_ptr<Playlist> playlist = _playlists[dt];
+       uint32_t n;
+       boost::shared_ptr<ChannelList> c = channels.reader();
+       ChannelList::iterator chan;
+       sampleoffset_t disk_samples_to_consume;
+       MonitorState ms = _route->monitoring_state ();
 
-       if (playlist) {
-               newname = Playlist::bump_name (playlist->name(), _session);
+       if (_active) {
+               if (!_pending_active) {
+                       _active = false;
+                       return;
+               }
        } else {
-               newname = Playlist::bump_name (_name, _session);
+               if (_pending_active) {
+                       _active = true;
+               } else {
+                       return;
+               }
        }
 
-       playlist = boost::dynamic_pointer_cast<AudioPlaylist> (PlaylistFactory::create (dt, _session, newname, hidden()));
-
-       if (!playlist) {
-               return -1;
+       if ((speed == 0.0) && (ms == MonitoringDisk)) {
+               /* no channels, or stopped. Don't accidentally pass any data
+                * from disk into our outputs (e.g. via interpolation)
+                */
+               return;
        }
 
-       return use_playlist (dt, playlist);
-}
+       BufferSet& scratch_bufs (_session.get_scratch_buffers (bufs.count()));
+       const bool still_locating = _session.global_locate_pending();
 
-int
-DiskReader::use_copy_playlist (DataType dt)
-{
-       assert (_playlists[dt]);
-
-       if (_playlists[dt] == 0) {
-               error << string_compose(_("DiskReader %1: there is no existing playlist to make a copy of!"), _name) << endmsg;
-               return -1;
+       if (c->empty()) {
+               /* do nothing with audio */
+               goto midi;
        }
 
-       string newname;
-       boost::shared_ptr<Playlist> playlist;
-
-       newname = Playlist::bump_name (_playlists[dt]->name(), _session);
+       assert (speed == -1 || speed == 0 || speed == 1);
 
-       if ((playlist = PlaylistFactory::create (_playlists[dt], newname)) == 0) {
-               return -1;
+       if (speed < 0) {
+               disk_samples_to_consume = -nframes;
+       } else if (speed > 0) {
+               disk_samples_to_consume = nframes;
+       } else {
+               disk_samples_to_consume = 0;
        }
 
-       playlist->reset_shares();
-
-       return use_playlist (dt, playlist);
-}
+       if (!result_required || ((ms & MonitoringDisk) == 0) || still_locating || _no_disk_output) {
 
+               /* no need for actual disk data, just advance read pointer and return */
 
-/** Do some record stuff [not described in this comment!]
- *
- *  Also:
- *    - Setup playback_distance with the nframes, or nframes adjusted
- *      for current varispeed, if appropriate.
- *    - Setup current_buffer in each ChannelInfo to point to data
- *      that someone can read playback_distance worth of data from.
- */
-void
-DiskReader::run (BufferSet& bufs, framepos_t start_frame, framepos_t end_frame,
-                 double speed, pframes_t nframes, bool result_required)
-{
-       uint32_t n;
-       boost::shared_ptr<ChannelList> c = channels.reader();
-       ChannelList::iterator chan;
-       framecnt_t playback_distance = 0;
-
-       Glib::Threads::Mutex::Lock sm (state_lock, Glib::Threads::TRY_LOCK);
-
-       if (!sm.locked()) {
-               return;
-       }
+               if (!still_locating || _no_disk_output) {
+                       for (ChannelList::iterator chan = c->begin(); chan != c->end(); ++chan) {
+                               (*chan)->rbuf->increment_read_ptr (disk_samples_to_consume);
+                       }
+               }
 
-       for (chan = c->begin(); chan != c->end(); ++chan) {
-               (*chan)->current_buffer = 0;
-       }
+               /* if monitoring disk but locating put silence in the buffers */
 
-       const bool need_disk_signal = result_required || _monitoring_choice == MonitorDisk || _monitoring_choice == MonitorCue;
+               if ((_no_disk_output || still_locating) && (ms == MonitoringDisk)) {
+                       bufs.silence (nframes, 0);
+               }
 
-       if (need_disk_signal) {
+       } else {
 
-               /* we're doing playback */
+               /* we need audio data from disk */
 
-               framecnt_t necessary_samples;
+               size_t n_buffers = bufs.count().n_audio();
+               size_t n_chans = c->size();
+               gain_t scaling;
 
-               if (_actual_speed != 1.0) {
-                       necessary_samples = (framecnt_t) ceil ((nframes * fabs (_actual_speed))) + 2;
+               if (n_chans > n_buffers) {
+                       scaling = ((float) n_buffers)/n_chans;
                } else {
-                       necessary_samples = nframes;
+                       scaling = 1.0;
                }
 
-               for (chan = c->begin(); chan != c->end(); ++chan) {
-                       (*chan)->buf->get_read_vector (&(*chan)->read_vector);
-               }
-
-               n = 0;
-
-               /* Setup current_buffer in each ChannelInfo to point to data that someone
-                  can read necessary_samples (== nframes at a transport speed of 1) worth of data
-                  from right now.
-               */
-
-               for (chan = c->begin(); chan != c->end(); ++chan, ++n) {
+               for (n = 0, chan = c->begin(); chan != c->end(); ++chan, ++n) {
 
                        ChannelInfo* chaninfo (*chan);
+                       AudioBuffer& output (bufs.get_audio (n%n_buffers));
+                       Sample* disk_signal = 0; /* assignment not really needed but it keeps the compiler quiet and helps track bugs */
 
-                       if (necessary_samples <= (framecnt_t) chaninfo->read_vector.len[0]) {
-                               /* There are enough samples in the first part of the ringbuffer */
-                               chaninfo->current_buffer = chaninfo->read_vector.buf[0];
-
+                       if (ms & MonitoringInput) {
+                               /* put disk stream in scratch buffer, blend at end */
+                               disk_signal = scratch_bufs.get_audio(n).data ();
                        } else {
-                               framecnt_t total = chaninfo->read_vector.len[0] + chaninfo->read_vector.len[1];
-
-                               if (necessary_samples > total) {
-                                       cerr << _name << " Need " << necessary_samples << " total = " << total << endl;
-                                       cerr << "underrun for " << _name << endl;
-                                        DEBUG_TRACE (DEBUG::Butler, string_compose ("%1 underrun in %2, total space = %3\n",
-                                                                                    DEBUG_THREAD_SELF, name(), total));
-                                       Underrun ();
-                                       return;
-
-                               } else {
-
-                                       /* We have enough samples, but not in one lump.  Coalesce the two parts
-                                          into one in wrap_buffer in our ChannelInfo, and specify that
-                                          as our current_buffer.
-                                       */
-
-                                       assert(wrap_buffer_size >= necessary_samples);
-
-                                       /* Copy buf[0] from buf */
-                                       memcpy ((char *) chaninfo->wrap_buffer,
-                                                       chaninfo->read_vector.buf[0],
-                                                       chaninfo->read_vector.len[0] * sizeof (Sample));
-
-                                       /* Copy buf[1] from buf */
-                                       memcpy (chaninfo->wrap_buffer + chaninfo->read_vector.len[0],
-                                                       chaninfo->read_vector.buf[1],
-                                                       (necessary_samples - chaninfo->read_vector.len[0])
-                                                                       * sizeof (Sample));
+                               /* no input stream needed, just overwrite buffers */
+                               disk_signal = output.data ();
+                       }
 
-                                       chaninfo->current_buffer = chaninfo->wrap_buffer;
+                       if (speed > 0) {
+                               if (start_sample < playback_sample) {
+                                       cerr << owner()->name() << " SS = " << start_sample << " PS = " << playback_sample << endl;
+                                       abort ();
+                               }
+                       } else if (speed < 0) {
+                               if (playback_sample < start_sample) {
+                                       cerr << owner()->name() << " SS = " << start_sample << " PS = " << playback_sample << " REVERSE" << endl;
+                                       abort ();
                                }
                        }
-               }
-
-               if (_actual_speed != 1.0f && _actual_speed != -1.0f) {
-
-                       interpolation.set_speed (_target_speed);
 
-                       int channel = 0;
-                       for (ChannelList::iterator chan = c->begin(); chan != c->end(); ++chan, ++channel) {
-                               ChannelInfo* chaninfo (*chan);
+                       if ((speed > 0) && (start_sample != playback_sample)) {
+                               cerr << owner()->name() << " playback not aligned, jump ahead " << (start_sample - playback_sample) << endl;
 
-                               playback_distance = interpolation.interpolate (
-                                       channel, nframes, chaninfo->current_buffer, chaninfo->speed_buffer);
-
-                               chaninfo->current_buffer = chaninfo->speed_buffer;
+                               if (can_internal_playback_seek (start_sample - playback_sample)) {
+                                       internal_playback_seek (start_sample - playback_sample);
+                               } else {
+                                       cerr << owner()->name() << " playback not possible: ss = " << start_sample << " ps = " << playback_sample << endl;
+                                       goto midi;
+                               }
                        }
 
-               } else {
-                       playback_distance = nframes;
-               }
-
-               _speed = _target_speed;
-       }
+                       chaninfo->rbuf->get_read_vector (&(*chan)->rw_vector);
 
-       if (need_disk_signal) {
+                       if (disk_samples_to_consume <= (samplecnt_t) chaninfo->rw_vector.len[0]) {
 
-               /* copy data over to buffer set */
+                               if (speed != 0.0) {
+                                       memcpy (disk_signal, chaninfo->rw_vector.buf[0], sizeof (Sample) * disk_samples_to_consume);
+                               }
 
-               size_t n_buffers = bufs.count().n_audio();
-               size_t n_chans = c->size();
-               gain_t scaling = 1.0f;
+                       } else {
 
-               if (n_chans > n_buffers) {
-                       scaling = ((float) n_buffers)/n_chans;
-               }
+                               const samplecnt_t total = chaninfo->rw_vector.len[0] + chaninfo->rw_vector.len[1];
 
-               for (n = 0, chan = c->begin(); chan != c->end(); ++chan, ++n) {
+                               if (disk_samples_to_consume <= total) {
 
-                       AudioBuffer& buf (bufs.get_audio (n%n_buffers));
-                       ChannelInfo* chaninfo (*chan);
+                                               if (speed != 0.0) {
+                                                       memcpy (disk_signal,
+                                                       chaninfo->rw_vector.buf[0],
+                                                       chaninfo->rw_vector.len[0] * sizeof (Sample));
+                                                       memcpy (disk_signal + chaninfo->rw_vector.len[0],
+                                                       chaninfo->rw_vector.buf[1],
+                                                       (disk_samples_to_consume - chaninfo->rw_vector.len[0]) * sizeof (Sample));
+                                       }
 
-                       if (n < n_chans) {
-                               if (scaling != 1.0f) {
-                                       buf.read_from_with_gain (chaninfo->current_buffer, nframes, scaling);
-                               } else {
-                                       buf.read_from (chaninfo->current_buffer, nframes);
-                               }
-                       } else {
-                               if (scaling != 1.0f) {
-                                       buf.accumulate_with_gain_from (chaninfo->current_buffer, nframes, scaling);
                                } else {
-                                       buf.accumulate_from (chaninfo->current_buffer, nframes);
-                               }
-                       }
-               }
 
-               /* extra buffers will already be silent, so leave them alone */
-       }
+                                       cerr << _name << " Need " << disk_samples_to_consume << " total = " << total << endl;
+                                       cerr << "underrun for " << _name << endl;
+                                       DEBUG_TRACE (DEBUG::Butler, string_compose ("%1 underrun in %2, total space = %3\n",
+                                                                                   DEBUG_THREAD_SELF, name(), total));
+                                       Underrun ();
+                                       return;
 
-       _need_butler = false;
+                               }
+                       }
 
-       if (_actual_speed < 0.0) {
-               playback_sample -= playback_distance;
-       } else {
-               playback_sample += playback_distance;
-       }
+                       if (scaling != 1.0f && speed != 0.0) {
+                               apply_gain_to_buffer (disk_signal, disk_samples_to_consume, scaling);
+                       }
 
-       for (ChannelList::iterator chan = c->begin(); chan != c->end(); ++chan) {
-               (*chan)->buf->increment_read_ptr (playback_distance);
-       }
+                       chaninfo->rbuf->increment_read_ptr (disk_samples_to_consume);
 
-       if (!c->empty()) {
-               if (_slaved) {
-                       if (c->front()->buf->write_space() >= c->front()->buf->bufsize() / 2) {
-                               _need_butler = true;
-                       }
-               } else {
-                       if ((framecnt_t) c->front()->buf->write_space() >= _chunk_frames) {
-                               _need_butler = true;
+                       if (ms & MonitoringInput) {
+                               /* mix the disk signal into the input signal (already in bufs) */
+                               mix_buffers_no_gain (output.data(), disk_signal, disk_samples_to_consume);
                        }
                }
        }
 
        /* MIDI data handling */
 
-       if (_actual_speed != 1.0f && _target_speed > 0) {
-
-               interpolation.set_speed (_target_speed);
+  midi:
+       if (/*!_session.declick_out_pending() && */ bufs.count().n_midi()) {
+               MidiBuffer* dst;
 
-               playback_distance = midi_interpolation.distance  (nframes);
+               if (_no_disk_output) {
+                       dst = &scratch_bufs.get_midi(0);
+               } else {
+                       dst = &bufs.get_midi (0);
+               }
 
-       } else {
-               playback_distance = nframes;
+               if ((ms & MonitoringDisk) && !still_locating) {
+                       get_midi_playback (*dst, start_sample, end_sample, ms, scratch_bufs, speed, disk_samples_to_consume);
+               }
        }
 
-       if (need_disk_signal && !_session.declick_out_pending()) {
-
-               /* copy the diskstream data to all output buffers */
+       if (!still_locating) {
 
-               MidiBuffer& mbuf (bufs.get_midi (0));
-               get_playback (mbuf, playback_distance);
+               bool butler_required = false;
 
-               /* leave the audio count alone */
-               ChanCount cnt (DataType::MIDI, 1);
-               cnt.set (DataType::AUDIO, bufs.count().n_audio());
-               bufs.set_count (cnt);
+               if (speed < 0.0) {
+                       playback_sample -= disk_samples_to_consume;
+               } else {
+                       playback_sample += disk_samples_to_consume;
+               }
 
-               /* vari-speed */
-               if (_target_speed > 0 && _actual_speed != 1.0f) {
-                       MidiBuffer& mbuf (bufs.get_midi (0));
-                       for (MidiBuffer::iterator i = mbuf.begin(); i != mbuf.end(); ++i) {
-                               MidiBuffer::TimeType *tme = i.timeptr();
-                               *tme = (*tme) * nframes / playback_distance;
+               if (_playlists[DataType::AUDIO]) {
+                       if (!c->empty()) {
+                               if (_slaved) {
+                                       if (c->front()->rbuf->write_space() >= c->front()->rbuf->bufsize() / 2) {
+                                               DEBUG_TRACE (DEBUG::Butler, string_compose ("%1: slaved, write space = %2 of %3\n", name(), c->front()->rbuf->write_space(), c->front()->rbuf->bufsize()));
+                                               butler_required = true;
+                                       }
+                               } else {
+                                       if ((samplecnt_t) c->front()->rbuf->write_space() >= _chunk_samples) {
+                                               DEBUG_TRACE (DEBUG::Butler, string_compose ("%1: write space = %2 of %3\n", name(), c->front()->rbuf->write_space(),
+                                                                                           _chunk_samples));
+                                               butler_required = true;
+                                       }
+                               }
                        }
                }
-       }
 
-       /* MIDI butler needed part */
+               if (_playlists[DataType::MIDI]) {
+                       /* MIDI butler needed part */
 
-       uint32_t frames_read = g_atomic_int_get(const_cast<gint*>(&_frames_read_from_ringbuffer));
-       uint32_t frames_written = g_atomic_int_get(const_cast<gint*>(&_frames_written_to_ringbuffer));
+                       uint32_t samples_read = g_atomic_int_get(const_cast<gint*>(&_samples_read_from_ringbuffer));
+                       uint32_t samples_written = g_atomic_int_get(const_cast<gint*>(&_samples_written_to_ringbuffer));
 
-       /*
-         cerr << name() << " MDS written: " << frames_written << " - read: " << frames_read <<
-         " = " << frames_written - frames_read
-         << " + " << playback_distance << " < " << midi_readahead << " = " << need_butler << ")" << endl;
-       */
+                       /*
+                         cerr << name() << " MDS written: " << samples_written << " - read: " << samples_read <<
+                         " = " << samples_written - samples_read
+                         << " + " << disk_samples_to_consume << " < " << midi_readahead << " = " << need_butler << ")" << endl;
+                       */
 
-       /* frames_read will generally be less than frames_written, but
-        * immediately after an overwrite, we can end up having read some data
-        * before we've written any. we don't need to trip an assert() on this,
-        * but we do need to check so that the decision on whether or not we
-        * need the butler is done correctly.
-        */
+                       /* samples_read will generally be less than samples_written, but
+                        * immediately after an overwrite, we can end up having read some data
+                        * before we've written any. we don't need to trip an assert() on this,
+                        * but we do need to check so that the decision on whether or not we
+                        * need the butler is done correctly.
+                        */
+
+                       /* furthermore..
+                        *
+                        * Doing heavy GUI operations[1] can stall also the butler.
+                        * The RT-thread meanwhile will happily continue and
+                        * â€˜samples_read’ (from buffer to output) will become larger
+                        * than â€˜samples_written’ (from disk to buffer).
+                        *
+                        * The disk-stream is now behind..
+                        *
+                        * In those cases the butler needs to be summed to refill the buffer (done now)
+                        * AND we need to skip (samples_read - samples_written). ie remove old events
+                        * before playback_sample from the rinbuffer.
+                        *
+                        * [1] one way to do so is described at #6170.
+                        * For me just popping up the context-menu on a MIDI-track header
+                        * of a track with a large (think beethoven :) midi-region also did the
+                        * trick. The playhead stalls for 2 or 3 sec, until the context-menu shows.
+                        *
+                        * In both cases the root cause is that redrawing MIDI regions on the GUI is still very slow
+                        * and can stall
+                        */
+                       if (samples_read <= samples_written) {
+                               if ((samples_written - samples_read) + disk_samples_to_consume < midi_readahead) {
+                                       butler_required = true;
+                               }
+                       } else {
+                               butler_required = true;
+                       }
 
-       /* furthermore..
-        *
-        * Doing heavy GUI operations[1] can stall also the butler.
-        * The RT-thread meanwhile will happily continue and
-        * â€˜frames_read’ (from buffer to output) will become larger
-        * than â€˜frames_written’ (from disk to buffer).
-        *
-        * The disk-stream is now behind..
-        *
-        * In those cases the butler needs to be summed to refill the buffer (done now)
-        * AND we need to skip (frames_read - frames_written). ie remove old events
-        * before playback_sample from the rinbuffer.
-        *
-        * [1] one way to do so is described at #6170.
-        * For me just popping up the context-menu on a MIDI-track header
-        * of a track with a large (think beethoven :) midi-region also did the
-        * trick. The playhead stalls for 2 or 3 sec, until the context-menu shows.
-        *
-        * In both cases the root cause is that redrawing MIDI regions on the GUI is still very slow
-        * and can stall
-        */
-       if (frames_read <= frames_written) {
-               if ((frames_written - frames_read) + playback_distance < midi_readahead) {
-                       _need_butler = true;
                }
-       } else {
-               _need_butler = true;
-       }
-
-       /* make sure bufs shows whatever data we had available */
 
-       ChanCount cnt;
-       cnt.set (DataType::MIDI, 1);
-       cnt.set (DataType::AUDIO, bufs.count().n_audio());
-       bufs.set_count (cnt);
-}
-
-frameoffset_t
-DiskReader::calculate_playback_distance (pframes_t nframes)
-{
-       frameoffset_t playback_distance = nframes;
-
-       if (_actual_speed != 1.0f && _actual_speed != -1.0f) {
-               interpolation.set_speed (_target_speed);
-               boost::shared_ptr<ChannelList> c = channels.reader();
-               int channel = 0;
-               for (ChannelList::iterator chan = c->begin(); chan != c->end(); ++chan, ++channel) {
-                       playback_distance = interpolation.interpolate (channel, nframes, NULL, NULL);
-               }
-       } else {
-               playback_distance = nframes;
+               _need_butler = butler_required;
        }
 
-       if (_actual_speed < 0.0) {
-               return -playback_distance;
-       } else {
-               return playback_distance;
-       }
+       // DEBUG_TRACE (DEBUG::Butler, string_compose ("%1 reader run, needs butler = %2\n", name(), _need_butler));
 }
 
 void
@@ -801,11 +510,11 @@ DiskReader::set_pending_overwrite (bool yn)
 
        _pending_overwrite = yn;
 
-       overwrite_frame = playback_sample;
+       overwrite_sample = playback_sample;
 
        boost::shared_ptr<ChannelList> c = channels.reader ();
        if (!c->empty ()) {
-               overwrite_offset = c->front()->buf->get_read_ptr();
+               overwrite_offset = c->front()->rbuf->get_read_ptr();
        }
 }
 
@@ -818,17 +527,19 @@ DiskReader::overwrite_existing_buffers ()
 
        overwrite_queued = false;
 
+       DEBUG_TRACE (DEBUG::DiskIO, string_compose ("%1 overwriting existing buffers at %2\n", overwrite_sample));
+
        if (!c->empty ()) {
 
                /* AUDIO */
 
-               bool reversed = (_visible_speed * _session.transport_speed()) < 0.0f;
+               const bool reversed = _session.transport_speed() < 0.0f;
 
                /* assume all are the same size */
-               framecnt_t size = c->front()->buf->bufsize();
+               samplecnt_t size = c->front()->rbuf->bufsize();
 
-               std::auto_ptr<Sample> mixdown_buffer (new Sample[size]);
-               std::auto_ptr<float> gain_buffer (new float[size]);
+               boost::scoped_array<Sample> mixdown_buffer (new Sample[size]);
+               boost::scoped_array<float> gain_buffer (new float[size]);
 
                /* reduce size so that we can fill the buffer correctly (ringbuffers
                   can only handle size-1, otherwise they appear to be empty)
@@ -836,12 +547,12 @@ DiskReader::overwrite_existing_buffers ()
                size--;
 
                uint32_t n=0;
-               framepos_t start;
+               samplepos_t start;
 
                for (ChannelList::iterator chan = c->begin(); chan != c->end(); ++chan, ++n) {
 
-                       start = overwrite_frame;
-                       framecnt_t cnt = size;
+                       start = overwrite_sample;
+                       samplecnt_t cnt = size;
 
                        /* to fill the buffer without resetting the playback sample, we need to
                           do it one or two chunks (normally two).
@@ -854,10 +565,10 @@ DiskReader::overwrite_existing_buffers ()
 
                        */
 
-                       framecnt_t to_read = size - overwrite_offset;
+                       samplecnt_t to_read = size - overwrite_offset;
 
-                       if (audio_read ((*chan)->buf->buffer() + overwrite_offset, mixdown_buffer.get(), gain_buffer.get(), start, to_read, n, reversed)) {
-                               error << string_compose(_("DiskReader %1: when refilling, cannot read %2 from playlist at frame %3"),
+                       if (audio_read ((*chan)->rbuf->buffer() + overwrite_offset, mixdown_buffer.get(), gain_buffer.get(), start, to_read, n, reversed)) {
+                               error << string_compose(_("DiskReader %1: when refilling, cannot read %2 from playlist at sample %3"),
                                                        id(), size, playback_sample) << endmsg;
                                goto midi;
                        }
@@ -866,8 +577,8 @@ DiskReader::overwrite_existing_buffers ()
 
                                cnt -= to_read;
 
-                               if (audio_read ((*chan)->buf->buffer(), mixdown_buffer.get(), gain_buffer.get(), start, cnt, n, reversed)) {
-                                       error << string_compose(_("DiskReader %1: when refilling, cannot read %2 from playlist at frame %3"),
+                               if (audio_read ((*chan)->rbuf->buffer(), mixdown_buffer.get(), gain_buffer.get(), start, cnt, n, reversed)) {
+                                       error << string_compose(_("DiskReader %1: when refilling, cannot read %2 from playlist at sample %3"),
                                                                id(), size, playback_sample) << endmsg;
                                        goto midi;
                                }
@@ -888,19 +599,18 @@ DiskReader::overwrite_existing_buffers ()
                _midi_buf->reset ();
                _midi_buf->reset_tracker ();
 
-               g_atomic_int_set (&_frames_read_from_ringbuffer, 0);
-               g_atomic_int_set (&_frames_written_to_ringbuffer, 0);
+               g_atomic_int_set (&_samples_read_from_ringbuffer, 0);
+               g_atomic_int_set (&_samples_written_to_ringbuffer, 0);
 
                /* Resolve all currently active notes in the playlist.  This is more
                   aggressive than it needs to be: ideally we would only resolve what is
                   absolutely necessary, but this seems difficult and/or impossible without
                   having the old data or knowing what change caused the overwrite.
                */
-               midi_playlist()->resolve_note_trackers (*_midi_buf, overwrite_frame);
-
-               midi_read (overwrite_frame, _chunk_frames, false);
+               midi_playlist()->resolve_note_trackers (*_midi_buf, overwrite_sample);
 
-               file_frame = overwrite_frame; // it was adjusted by ::midi_read()
+               midi_read (overwrite_sample, _chunk_samples, false);
+               file_sample[DataType::MIDI] = overwrite_sample; // overwrite_sample was adjusted by ::midi_read() to the new position
        }
 
        _pending_overwrite = false;
@@ -908,33 +618,21 @@ DiskReader::overwrite_existing_buffers ()
        return ret;
 }
 
-void
-DiskReader::non_realtime_locate (framepos_t location)
-{
-       /* now refill channel buffers */
-
-       if (speed() != 1.0f || speed() != -1.0f) {
-               seek ((framepos_t) (location * (double) speed()), true);
-       } else {
-               seek (location, true);
-       }
-}
-
 int
-DiskReader::seek (framepos_t frame, bool complete_refill)
+DiskReader::seek (samplepos_t sample, bool complete_refill)
 {
        uint32_t n;
        int ret = -1;
        ChannelList::iterator chan;
        boost::shared_ptr<ChannelList> c = channels.reader();
 
-       Glib::Threads::Mutex::Lock lm (state_lock);
+       //sample = std::max ((samplecnt_t)0, sample -_session.worst_output_latency ());
 
        for (n = 0, chan = c->begin(); chan != c->end(); ++chan, ++n) {
-               (*chan)->buf->reset ();
+               (*chan)->rbuf->reset ();
        }
 
-       if (g_atomic_int_get (&_frames_read_from_ringbuffer) == 0) {
+       if (g_atomic_int_get (&_samples_read_from_ringbuffer) == 0) {
                /* we haven't read anything since the last seek,
                   so flush all note trackers to prevent
                   wierdness
@@ -943,11 +641,12 @@ DiskReader::seek (framepos_t frame, bool complete_refill)
        }
 
        _midi_buf->reset();
-       g_atomic_int_set(&_frames_read_from_ringbuffer, 0);
-       g_atomic_int_set(&_frames_written_to_ringbuffer, 0);
+       g_atomic_int_set(&_samples_read_from_ringbuffer, 0);
+       g_atomic_int_set(&_samples_written_to_ringbuffer, 0);
 
-       playback_sample = frame;
-       file_frame = frame;
+       playback_sample = sample;
+       file_sample[DataType::AUDIO] = sample;
+       file_sample[DataType::MIDI] = sample;
 
        if (complete_refill) {
                /* call _do_refill() to refill the entire buffer, using
@@ -966,7 +665,7 @@ DiskReader::seek (framepos_t frame, bool complete_refill)
 }
 
 int
-DiskReader::can_internal_playback_seek (framecnt_t distance)
+DiskReader::can_internal_playback_seek (samplecnt_t distance)
 {
        /* 1. Audio */
 
@@ -974,27 +673,27 @@ DiskReader::can_internal_playback_seek (framecnt_t distance)
        boost::shared_ptr<ChannelList> c = channels.reader();
 
        for (chan = c->begin(); chan != c->end(); ++chan) {
-               if ((*chan)->buf->read_space() < (size_t) distance) {
+               if ((*chan)->rbuf->read_space() < (size_t) distance) {
                        return false;
                }
        }
 
        /* 2. MIDI */
 
-       uint32_t frames_read    = g_atomic_int_get(&_frames_read_from_ringbuffer);
-       uint32_t frames_written = g_atomic_int_get(&_frames_written_to_ringbuffer);
+       uint32_t samples_read    = g_atomic_int_get(&_samples_read_from_ringbuffer);
+       uint32_t samples_written = g_atomic_int_get(&_samples_written_to_ringbuffer);
 
-       return ((frames_written - frames_read) < distance);
+       return ((samples_written - samples_read) < distance);
 }
 
 int
-DiskReader::internal_playback_seek (framecnt_t distance)
+DiskReader::internal_playback_seek (samplecnt_t distance)
 {
        ChannelList::iterator chan;
        boost::shared_ptr<ChannelList> c = channels.reader();
 
        for (chan = c->begin(); chan != c->end(); ++chan) {
-               (*chan)->buf->increment_read_ptr (::llabs(distance));
+               (*chan)->rbuf->increment_read_ptr (::llabs(distance));
        }
 
        playback_sample += distance;
@@ -1014,28 +713,33 @@ void swap_by_ptr (Sample *first, Sample *last)
 
 /** Read some data for 1 channel from our playlist into a buffer.
  *  @param buf Buffer to write to.
- *  @param start Session frame to start reading from; updated to where we end up
+ *  @param start Session sample to start reading from; updated to where we end up
  *         after the read.
  *  @param cnt Count of samples to read.
  *  @param reversed true if we are running backwards, otherwise false.
  */
 int
 DiskReader::audio_read (Sample* buf, Sample* mixdown_buffer, float* gain_buffer,
-                        framepos_t& start, framecnt_t cnt,
+                        samplepos_t& start, samplecnt_t cnt,
                         int channel, bool reversed)
 {
-       framecnt_t this_read = 0;
+       samplecnt_t this_read = 0;
        bool reloop = false;
-       framepos_t loop_end = 0;
-       framepos_t loop_start = 0;
-       framecnt_t offset = 0;
+       samplepos_t loop_end = 0;
+       samplepos_t loop_start = 0;
+       samplecnt_t offset = 0;
        Location *loc = 0;
 
+       if (!_playlists[DataType::AUDIO]) {
+               memset (buf, 0, sizeof (Sample) * cnt);
+               return 0;
+       }
+
        /* XXX we don't currently play loops in reverse. not sure why */
 
        if (!reversed) {
 
-               framecnt_t loop_length = 0;
+               samplecnt_t loop_length = 0;
 
                /* Make the use of a Location atomic for this read operation.
 
@@ -1045,13 +749,13 @@ DiskReader::audio_read (Sample* buf, Sample* mixdown_buffer, float* gain_buffer,
                   just once.
                */
 
-               if ((loc = loop_location) != 0) {
+               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
+               /* if we are looping, ensure that the first sample we read is at the correct
                   position within the loop.
                */
 
@@ -1088,7 +792,7 @@ DiskReader::audio_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(_("DiskReader %1: cannot read %2 from playlist at frame %3"), id(), this_read,
+                       error << string_compose(_("DiskReader %1: cannot read %2 from playlist at sample %3"), id(), this_read,
                                         start) << endmsg;
                        return -1;
                }
@@ -1125,10 +829,10 @@ DiskReader::_do_refill_with_alloc (bool partial_fill)
        */
 
        {
-               std::auto_ptr<Sample> mix_buf (new Sample[2*1048576]);
-               std::auto_ptr<float>  gain_buf (new float[2*1048576]);
+               boost::scoped_array<Sample> mix_buf (new Sample[2*1048576]);
+               boost::scoped_array<float>  gain_buf (new float[2*1048576]);
 
-               int ret = refill_audio (mix_buf.get(), gain_buf.get(), (partial_fill ? _chunk_frames : 0));
+               int ret = refill_audio (mix_buf.get(), gain_buf.get(), (partial_fill ? _chunk_samples : 0));
 
                if (ret) {
                        return ret;
@@ -1139,7 +843,7 @@ DiskReader::_do_refill_with_alloc (bool partial_fill)
 }
 
 int
-DiskReader::refill (Sample* mixdown_buffer, float* gain_buffer, framecnt_t fill_level)
+DiskReader::refill (Sample* mixdown_buffer, float* gain_buffer, samplecnt_t fill_level)
 {
        int ret = refill_audio (mixdown_buffer, gain_buffer, fill_level);
 
@@ -1161,26 +865,26 @@ DiskReader::refill (Sample* mixdown_buffer, float* gain_buffer, framecnt_t fill_
  */
 
 int
-DiskReader::refill_audio (Sample* mixdown_buffer, float* gain_buffer, framecnt_t fill_level)
+DiskReader::refill_audio (Sample* mixdown_buffer, float* gain_buffer, samplecnt_t fill_level)
 {
-       if (_session.state_of_the_state() & Session::Loading) {
+       /* do not read from disk while session is marked as Loading, to avoid
+          useless redundant I/O.
+       */
+
+       if (_session.loading()) {
                return 0;
        }
 
        int32_t ret = 0;
-       framecnt_t to_read;
+       samplecnt_t to_read;
        RingBufferNPT<Sample>::rw_vector vector;
-       bool const reversed = (_visible_speed * _session.transport_speed()) < 0.0f;
-       framecnt_t total_space;
-       framecnt_t zero_fill;
+       bool const reversed = _session.transport_speed() < 0.0f;
+       samplecnt_t total_space;
+       samplecnt_t zero_fill;
        uint32_t chan_n;
        ChannelList::iterator i;
        boost::shared_ptr<ChannelList> c = channels.reader();
-       framecnt_t ts;
-
-       /* do not read from disk while session is marked as Loading, to avoid
-          useless redundant I/O.
-       */
+       samplecnt_t ts;
 
        if (c->empty()) {
                return 0;
@@ -1194,9 +898,10 @@ DiskReader::refill_audio (Sample* mixdown_buffer, float* gain_buffer, framecnt_t
        vector.buf[1] = 0;
        vector.len[1] = 0;
 
-       c->front()->buf->get_write_vector (&vector);
+       c->front()->rbuf->get_write_vector (&vector);
 
        if ((total_space = vector.len[0] + vector.len[1]) == 0) {
+               DEBUG_TRACE (DEBUG::DiskIO, string_compose ("%1: no space to refill\n", name()));
                /* nowhere to write to */
                return 0;
        }
@@ -1211,17 +916,18 @@ DiskReader::refill_audio (Sample* mixdown_buffer, float* gain_buffer, framecnt_t
        }
 
        /* if we're running close to normal speed and there isn't enough
-          space to do disk_read_chunk_frames of I/O, then don't bother.
+          space to do disk_read_chunk_samples 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.
 
-          Note: it is a design assumption that disk_read_chunk_frames is smaller
+          Note: it is a design assumption that disk_read_chunk_samples is smaller
           than the playback buffer size, so this check should never trip when
           the playback buffer is empty.
        */
 
-       if ((total_space < _chunk_frames) && fabs (_actual_speed) < 2.0f) {
+       DEBUG_TRACE (DEBUG::DiskIO, string_compose ("%1: space to refill %2 vs. chunk %3 (speed = %4)\n", name(), total_space, _chunk_samples, _session.transport_speed()));
+       if ((total_space < _chunk_samples) && fabs (_session.transport_speed()) < 2.0f) {
                return 0;
        }
 
@@ -1230,37 +936,40 @@ DiskReader::refill_audio (Sample* mixdown_buffer, float* gain_buffer, framecnt_t
           work with.
        */
 
-       if (_slaved && total_space < (framecnt_t) (c->front()->buf->bufsize() / 2)) {
+       if (_slaved && total_space < (samplecnt_t) (c->front()->rbuf->bufsize() / 2)) {
+               DEBUG_TRACE (DEBUG::DiskIO, string_compose ("%1: not enough to refill while slaved\n", this));
                return 0;
        }
 
+       samplepos_t ffa = file_sample[DataType::AUDIO];
+
        if (reversed) {
 
-               if (file_frame == 0) {
+               if (ffa == 0) {
 
                        /* at start: nothing to do but fill with silence */
 
                        for (chan_n = 0, i = c->begin(); i != c->end(); ++i, ++chan_n) {
 
                                ChannelInfo* chan (*i);
-                               chan->buf->get_write_vector (&vector);
+                               chan->rbuf->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->buf->increment_write_ptr (vector.len[0] + vector.len[1]);
+                               chan->rbuf->increment_write_ptr (vector.len[0] + vector.len[1]);
                        }
                        return 0;
                }
 
-               if (file_frame < total_space) {
+               if (ffa < total_space) {
 
                        /* too close to the start: read what we can,
                           and then zero fill the rest
                        */
 
-                       zero_fill = total_space - file_frame;
-                       total_space = file_frame;
+                       zero_fill = total_space - ffa;
+                       total_space = ffa;
 
                } else {
 
@@ -1269,36 +978,36 @@ DiskReader::refill_audio (Sample* mixdown_buffer, float* gain_buffer, framecnt_t
 
        } else {
 
-               if (file_frame == max_framepos) {
+               if (ffa == max_samplepos) {
 
                        /* at end: nothing to do but fill with silence */
 
                        for (chan_n = 0, i = c->begin(); i != c->end(); ++i, ++chan_n) {
 
                                ChannelInfo* chan (*i);
-                               chan->buf->get_write_vector (&vector);
+                               chan->rbuf->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->buf->increment_write_ptr (vector.len[0] + vector.len[1]);
+                               chan->rbuf->increment_write_ptr (vector.len[0] + vector.len[1]);
                        }
                        return 0;
                }
 
-               if (file_frame > max_framepos - total_space) {
+               if (ffa > max_samplepos - total_space) {
 
                        /* to close to the end: read what we can, and zero fill the rest */
 
-                       zero_fill = total_space - (max_framepos - file_frame);
-                       total_space = max_framepos - file_frame;
+                       zero_fill = total_space - (max_samplepos - ffa);
+                       total_space = max_samplepos - ffa;
 
                } else {
                        zero_fill = 0;
                }
        }
 
-       framepos_t file_frame_tmp = 0;
+       samplepos_t file_sample_tmp = 0;
 
        /* total_space is in samples. We want to optimize read sizes in various sizes using bytes */
 
@@ -1315,11 +1024,9 @@ DiskReader::refill_audio (Sample* mixdown_buffer, float* gain_buffer, framecnt_t
 
        /* now back to samples */
 
-       framecnt_t samples_to_read = byte_size_for_read / (bits_per_sample / 8);
+       samplecnt_t samples_to_read = byte_size_for_read / (bits_per_sample / 8);
 
-       //cerr << name() << " will read " << byte_size_for_read << " out of total bytes " << total_bytes << " in buffer of "
-       // << c->front()->buf->bufsize() * bits_per_sample / 8 << " bps = " << bits_per_sample << endl;
-       // cerr << name () << " read samples = " << samples_to_read << " out of total space " << total_space << " in buffer of " << c->front()->buf->bufsize() << " samples\n";
+       DEBUG_TRACE (DEBUG::DiskIO, string_compose ("%1: will refill %2 channels with %3 samples\n", name(), c->size(), total_space));
 
        // uint64_t before = g_get_monotonic_time ();
        // uint64_t elapsed;
@@ -1329,18 +1036,18 @@ DiskReader::refill_audio (Sample* mixdown_buffer, float* gain_buffer, framecnt_t
                ChannelInfo* chan (*i);
                Sample* buf1;
                Sample* buf2;
-               framecnt_t len1, len2;
+               samplecnt_t len1, len2;
 
-               chan->buf->get_write_vector (&vector);
+               chan->rbuf->get_write_vector (&vector);
 
-               if ((framecnt_t) vector.len[0] > samples_to_read) {
+               if ((samplecnt_t) vector.len[0] > samples_to_read) {
 
                        /* 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_read_chunk_frames that would be filled
+                          ^^^^ => 1 x disk_read_chunk_samples that would be filled
 
                           |......|+++++++++++++|...............................|
                           buf1                buf0
@@ -1357,7 +1064,7 @@ DiskReader::refill_audio (Sample* mixdown_buffer, float* gain_buffer, framecnt_t
                }
 
                ts = total_space;
-               file_frame_tmp = file_frame;
+               file_sample_tmp = ffa;
 
                buf1 = vector.buf[0];
                len1 = vector.len[0];
@@ -1365,18 +1072,17 @@ DiskReader::refill_audio (Sample* mixdown_buffer, float* gain_buffer, framecnt_t
                len2 = vector.len[1];
 
                to_read = min (ts, len1);
-               to_read = min (to_read, (framecnt_t) samples_to_read);
+               to_read = min (to_read, (samplecnt_t) samples_to_read);
 
                assert (to_read >= 0);
 
                if (to_read) {
 
-                       if (audio_read (buf1, mixdown_buffer, gain_buffer, file_frame_tmp, to_read, chan_n, reversed)) {
+                       if (audio_read (buf1, mixdown_buffer, gain_buffer, file_sample_tmp, to_read, chan_n, reversed)) {
                                ret = -1;
                                goto out;
                        }
-
-                       chan->buf->increment_write_ptr (to_read);
+                       chan->rbuf->increment_write_ptr (to_read);
                        ts -= to_read;
                }
 
@@ -1389,12 +1095,12 @@ DiskReader::refill_audio (Sample* mixdown_buffer, float* gain_buffer, framecnt_t
                           all of vector.len[1] as well.
                        */
 
-                       if (audio_read (buf2, mixdown_buffer, gain_buffer, file_frame_tmp, to_read, chan_n, reversed)) {
+                       if (audio_read (buf2, mixdown_buffer, gain_buffer, file_sample_tmp, to_read, chan_n, reversed)) {
                                ret = -1;
                                goto out;
                        }
 
-                       chan->buf->increment_write_ptr (to_read);
+                       chan->rbuf->increment_write_ptr (to_read);
                }
 
                if (zero_fill) {
@@ -1404,21 +1110,21 @@ DiskReader::refill_audio (Sample* mixdown_buffer, float* gain_buffer, framecnt_t
        }
 
        // elapsed = g_get_monotonic_time () - before;
-       // cerr << "\tbandwidth = " << (byte_size_for_read / 1048576.0) / (elapsed/1000000.0) << "MB/sec\n";
+       // cerr << '\t' << name() << ": bandwidth = " << (byte_size_for_read / 1048576.0) / (elapsed/1000000.0) << "MB/sec\n";
 
-       file_frame = file_frame_tmp;
-       assert (file_frame >= 0);
+       file_sample[DataType::AUDIO] = file_sample_tmp;
+       assert (file_sample[DataType::AUDIO] >= 0);
 
-       ret = ((total_space - samples_to_read) > _chunk_frames);
+       ret = ((total_space - samples_to_read) > _chunk_samples);
 
-       c->front()->buf->get_write_vector (&vector);
+       c->front()->rbuf->get_write_vector (&vector);
 
   out:
        return ret;
 }
 
 void
-DiskReader::playlist_ranges_moved (list< Evoral::RangeMove<framepos_t> > const & movements_frames, bool from_undo)
+DiskReader::playlist_ranges_moved (list< Evoral::RangeMove<samplepos_t> > const & movements_samples, bool from_undo)
 {
        /* If we're coming from an undo, it will have handled
           automation undo (it must, since automation-follows-regions
@@ -1429,22 +1135,21 @@ DiskReader::playlist_ranges_moved (list< Evoral::RangeMove<framepos_t> > const &
                return;
        }
 
-#if 0
-       if (!_track || Config->get_automation_follows_regions () == false) {
+       if (!_route || Config->get_automation_follows_regions () == false) {
                return;
        }
 
        list< Evoral::RangeMove<double> > movements;
 
-       for (list< Evoral::RangeMove<framepos_t> >::const_iterator i = movements_frames.begin();
-            i != movements_frames.end();
+       for (list< Evoral::RangeMove<samplepos_t> >::const_iterator i = movements_samples.begin();
+            i != movements_samples.end();
             ++i) {
 
                movements.push_back(Evoral::RangeMove<double>(i->from, i->length, i->to));
        }
 
        /* move panner automation */
-       boost::shared_ptr<Pannable> pannable = _track->pannable();
+       boost::shared_ptr<Pannable> pannable = _route->pannable();
         Evoral::ControlSet::Controls& c (pannable->controls());
 
         for (Evoral::ControlSet::Controls::iterator ci = c.begin(); ci != c.end(); ++ci) {
@@ -1464,12 +1169,11 @@ DiskReader::playlist_ranges_moved (list< Evoral::RangeMove<framepos_t> > const &
                 }
         }
        /* move processor automation */
-       _track->foreach_processor (boost::bind (&Diskstream::move_processor_automation, this, _1, movements_frames));
-#endif
+        _route->foreach_processor (boost::bind (&DiskReader::move_processor_automation, this, _1, movements_samples));
 }
 
 void
-DiskReader::move_processor_automation (boost::weak_ptr<Processor> p, list< Evoral::RangeMove<framepos_t> > const & movements_frames)
+DiskReader::move_processor_automation (boost::weak_ptr<Processor> p, list< Evoral::RangeMove<samplepos_t> > const & movements_samples)
 {
        boost::shared_ptr<Processor> processor (p.lock ());
        if (!processor) {
@@ -1477,7 +1181,7 @@ DiskReader::move_processor_automation (boost::weak_ptr<Processor> p, list< Evora
        }
 
        list< Evoral::RangeMove<double> > movements;
-       for (list< Evoral::RangeMove<framepos_t> >::const_iterator i = movements_frames.begin(); i != movements_frames.end(); ++i) {
+       for (list< Evoral::RangeMove<samplepos_t> >::const_iterator i = movements_samples.begin(); i != movements_samples.end(); ++i) {
                movements.push_back(Evoral::RangeMove<double>(i->from, i->length, i->to));
        }
 
@@ -1500,16 +1204,6 @@ DiskReader::move_processor_automation (boost::weak_ptr<Processor> p, list< Evora
        }
 }
 
-boost::shared_ptr<MidiBuffer>
-DiskReader::get_gui_feed_buffer () const
-{
-       boost::shared_ptr<MidiBuffer> b (new MidiBuffer (AudioEngine::instance()->raw_buffer_size (DataType::MIDI)));
-
-       Glib::Threads::Mutex::Lock lm (_gui_feed_buffer_mutex);
-       b->copy (_gui_feed_buffer);
-       return b;
-}
-
 void
 DiskReader::reset_tracker ()
 {
@@ -1523,7 +1217,7 @@ DiskReader::reset_tracker ()
 }
 
 void
-DiskReader::resolve_tracker (Evoral::EventSink<framepos_t>& buffer, framepos_t time)
+DiskReader::resolve_tracker (Evoral::EventSink<samplepos_t>& buffer, samplepos_t time)
 {
        _midi_buf->resolve_tracker(buffer, time);
 
@@ -1534,143 +1228,159 @@ DiskReader::resolve_tracker (Evoral::EventSink<framepos_t>& buffer, framepos_t t
        }
 }
 
-void
-DiskReader::flush_playback (framepos_t start, framepos_t end)
-{
-       _midi_buf->flush (start, end);
-       g_atomic_int_add (&_frames_read_from_ringbuffer, end - start);
-}
-
 /** Writes playback events from playback_sample for nframes to dst, translating time stamps
  *  so that an event at playback_sample has time = 0
  */
 void
-DiskReader::get_playback (MidiBuffer& dst, framecnt_t nframes)
+DiskReader::get_midi_playback (MidiBuffer& dst, samplepos_t start_sample, samplepos_t end_sample, MonitorState ms, BufferSet& scratch_bufs, double speed, samplecnt_t disk_samples_to_consume)
 {
-       dst.clear();
+       MidiBuffer* target;
+       samplepos_t nframes = end_sample - start_sample;
 
-       Location* loc = loop_location;
+       if ((ms & MonitoringInput) == 0) {
+               /* Route::process_output_buffers() clears the buffer as-needed */
+               target = &dst;
+       } else {
+               target = &scratch_bufs.get_midi (0);
+       }
 
-       DEBUG_TRACE (DEBUG::MidiDiskstreamIO, string_compose (
-                            "%1 MDS pre-read read %8 offset = %9 @ %4..%5 from %2 write to %3, LOOPED ? %6 .. %7\n", _name,
-                            _midi_buf->get_read_ptr(), _midi_buf->get_write_ptr(), playback_sample, playback_sample + nframes,
-                            (loc ? loc->start() : -1), (loc ? loc->end() : -1), nframes, Port::port_offset()));
+       if (ms & MonitoringDisk) {
+               /* disk data needed */
 
-       //cerr << "======== PRE ========\n";
-       //_midi_buf->dump (cerr);
-       //cerr << "----------------\n";
+               Location* loc = _loop_location;
 
-       size_t events_read = 0;
+               DEBUG_TRACE (DEBUG::MidiDiskstreamIO, string_compose (
+                                    "%1 MDS pre-read read %8 offset = %9 @ %4..%5 from %2 write to %3, LOOPED ? %6 .. %7\n", _name,
+                                    _midi_buf->get_read_ptr(), _midi_buf->get_write_ptr(), start_sample, end_sample,
+                                    (loc ? loc->start() : -1), (loc ? loc->end() : -1), nframes, Port::port_offset()));
 
-       if (loc) {
-               framepos_t effective_start;
+               //cerr << "======== PRE ========\n";
+               //_midi_buf->dump (cerr);
+               //cerr << "----------------\n";
 
-               Evoral::Range<framepos_t> loop_range (loc->start(), loc->end() - 1);
-               effective_start = loop_range.squish (playback_sample);
+               size_t events_read = 0;
 
-               DEBUG_TRACE (DEBUG::MidiDiskstreamIO, string_compose ("looped, effective start adjusted to %1\n", effective_start));
+               if (loc) {
+                       samplepos_t effective_start;
 
-               if (effective_start == loc->start()) {
-                       /* We need to turn off notes that may extend
-                          beyond the loop end.
-                       */
+                       Evoral::Range<samplepos_t> loop_range (loc->start(), loc->end() - 1);
+                       effective_start = loop_range.squish (start_sample);
 
-                       _midi_buf->resolve_tracker (dst, 0);
-               }
+                       DEBUG_TRACE (DEBUG::MidiDiskstreamIO, string_compose ("looped, effective start adjusted to %1\n", effective_start));
 
-               /* for split-cycles we need to offset the events */
+                       if (effective_start == loc->start()) {
+                               /* We need to turn off notes that may extend
+                                  beyond the loop end.
+                               */
 
-               if (loc->end() >= effective_start && loc->end() < effective_start + nframes) {
+                               _midi_buf->resolve_tracker (*target, 0);
+                       }
 
-                       /* end of loop is within the range we are reading, so
-                          split the read in two, and lie about the location
-                          for the 2nd read
-                       */
+                       /* for split-cycles we need to offset the events */
 
-                       framecnt_t first, second;
+                       if (loc->end() >= effective_start && loc->end() < effective_start + nframes) {
 
-                       first = loc->end() - effective_start;
-                       second = nframes - first;
+                               /* end of loop is within the range we are reading, so
+                                  split the read in two, and lie about the location
+                                  for the 2nd read
+                               */
 
-                       DEBUG_TRACE (DEBUG::MidiDiskstreamIO, string_compose ("loop read for eff %1 end %2: %3 and %4, cycle offset %5\n",
-                                                                             effective_start, loc->end(), first, second));
+                               samplecnt_t first, second;
 
-                       if (first) {
-                               DEBUG_TRACE (DEBUG::MidiDiskstreamIO, string_compose ("loop read #1, from %1 for %2\n",
-                                                                                     effective_start, first));
-                               events_read = _midi_buf->read (dst, effective_start, first);
-                       }
+                               first = loc->end() - effective_start;
+                               second = nframes - first;
 
-                       if (second) {
-                               DEBUG_TRACE (DEBUG::MidiDiskstreamIO, string_compose ("loop read #2, from %1 for %2\n",
-                                                                                     loc->start(), second));
-                               events_read += _midi_buf->read (dst, loc->start(), second);
-                       }
+                               DEBUG_TRACE (DEBUG::MidiDiskstreamIO, string_compose ("loop read for eff %1 end %2: %3 and %4, cycle offset %5\n",
+                                                                                     effective_start, loc->end(), first, second));
+
+                               if (first) {
+                                       DEBUG_TRACE (DEBUG::MidiDiskstreamIO, string_compose ("loop read #1, from %1 for %2\n",
+                                                                                             effective_start, first));
+                                       events_read = _midi_buf->read (*target, effective_start, first);
+                               }
+
+                               if (second) {
+                                       DEBUG_TRACE (DEBUG::MidiDiskstreamIO, string_compose ("loop read #2, from %1 for %2\n",
+                                                                                             loc->start(), second));
+                                       events_read += _midi_buf->read (*target, loc->start(), second);
+                               }
 
+                       } else {
+                               DEBUG_TRACE (DEBUG::MidiDiskstreamIO, string_compose ("loop read #3, adjusted start as %1 for %2\n",
+                                                                                     effective_start, nframes));
+                               events_read = _midi_buf->read (*target, effective_start, effective_start + nframes);
+                       }
                } else {
-                       DEBUG_TRACE (DEBUG::MidiDiskstreamIO, string_compose ("loop read #3, adjusted start as %1 for %2\n",
-                                                                             effective_start, nframes));
-                       events_read = _midi_buf->read (dst, effective_start, effective_start + nframes);
-               }
-       } else {
-               const size_t n_skipped = _midi_buf->skip_to (playback_sample);
-               if (n_skipped > 0) {
-                       warning << string_compose(_("MidiDiskstream %1: skipped %2 events, possible underflow"), id(), n_skipped) << endmsg;
+                       const size_t n_skipped = _midi_buf->skip_to (start_sample);
+                       if (n_skipped > 0) {
+                               warning << string_compose(_("MidiDiskstream %1: skipped %2 events, possible underflow"), id(), n_skipped) << endmsg;
+                       }
+                       DEBUG_TRACE (DEBUG::MidiDiskstreamIO, string_compose ("playback buffer read, from %1 to %2 (%3)", start_sample, end_sample, nframes));
+                       events_read = _midi_buf->read (*target, start_sample, end_sample, Port::port_offset ());
                }
-               DEBUG_TRACE (DEBUG::MidiDiskstreamIO, string_compose ("playback buffer read, from %1 to %2 (%3)", playback_sample, playback_sample + nframes, nframes));
-               events_read = _midi_buf->read (dst, playback_sample, playback_sample + nframes);
+
+               DEBUG_TRACE (DEBUG::MidiDiskstreamIO, string_compose (
+                                    "%1 MDS events read %2 range %3 .. %4 rspace %5 wspace %6 r@%7 w@%8\n",
+                                    _name, events_read, playback_sample, playback_sample + nframes,
+                                    _midi_buf->read_space(), _midi_buf->write_space(),
+                                    _midi_buf->get_read_ptr(), _midi_buf->get_write_ptr()));
        }
 
-       DEBUG_TRACE (DEBUG::MidiDiskstreamIO, string_compose (
-                            "%1 MDS events read %2 range %3 .. %4 rspace %5 wspace %6 r@%7 w@%8\n",
-                            _name, events_read, playback_sample, playback_sample + nframes,
-                            _midi_buf->read_space(), _midi_buf->write_space(),
-                            _midi_buf->get_read_ptr(), _midi_buf->get_write_ptr()));
+       g_atomic_int_add (&_samples_read_from_ringbuffer, nframes);
 
-       g_atomic_int_add (&_frames_read_from_ringbuffer, nframes);
+       /* vari-speed */
+       if (speed != 0.0 && fabsf (speed) != 1.0f) {
+               for (MidiBuffer::iterator i = target->begin(); i != target->end(); ++i) {
+                       MidiBuffer::TimeType *tme = i.timeptr();
+                       // XXX need to subtract port offsets before scaling
+                       // also we must only scale events read from disk
+                       // and not existing input data in the buffer.
+                       *tme = (*tme) * nframes / disk_samples_to_consume;
+               }
+       }
 
-       //cerr << "======== POST ========\n";
-       //_midi_buf->dump (cerr);
-       //cerr << "----------------\n";
-}
+       if (ms & MonitoringInput) {
+               dst.merge_from (*target, nframes);
+       }
 
-/** Get the start, end, and length of a location "atomically".
- *
- * 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 start/length values
- * obtained just once.  Use this function to achieve this since location being
- * a parameter achieves this.
- */
-static void
-get_location_times(const Location* location,
-                   framepos_t*     start,
-                   framepos_t*     end,
-                   framepos_t*     length)
-{
-       if (location) {
-               *start  = location->start();
-               *end    = location->end();
-               *length = *end - *start;
+#if 0
+       if (!target->empty ()) {
+               cerr << "======== MIDI OUT ========\n";
+               for (MidiBuffer::iterator i = target->begin(); i != target->end(); ++i) {
+                       const Evoral::Event<MidiBuffer::TimeType> ev (*i, false);
+                       cerr << "MIDI EVENT (from disk) @ " << ev.time();
+                       for (size_t xx = 0; xx < ev.size(); ++xx) {
+                               cerr << ' ' << hex << (int) ev.buffer()[xx];
+                       }
+                       cerr << dec << endl;
+               }
+               cerr << "----------------\n";
        }
+#endif
+#if 0
+       cerr << "======== MIDI Disk Buffer ========\n";
+       _midi_buf->dump (cerr);
+       cerr << "----------------\n";
+#endif
 }
 
-/** @a start is set to the new frame position (TIME) read up to */
+/** @a start is set to the new sample position (TIME) read up to */
 int
-DiskReader::midi_read (framepos_t& start, framecnt_t dur, bool reversed)
+DiskReader::midi_read (samplepos_t& start, samplecnt_t dur, bool reversed)
 {
-       framecnt_t this_read   = 0;
-       framepos_t loop_end    = 0;
-       framepos_t loop_start  = 0;
-       framecnt_t loop_length = 0;
-       Location*  loc         = loop_location;
-       framepos_t effective_start = start;
-       Evoral::Range<framepos_t>*  loop_range (0);
+       samplecnt_t this_read   = 0;
+       samplepos_t loop_end    = 0;
+       samplepos_t loop_start  = 0;
+       samplecnt_t loop_length = 0;
+       Location*  loc         = _loop_location;
+       samplepos_t effective_start = start;
+       Evoral::Range<samplepos_t>*  loop_range (0);
 
-//     MidiTrack*         mt     = dynamic_cast<MidiTrack*>(_track);
-//     MidiChannelFilter* filter = mt ? &mt->playback_filter() : 0;
-       MidiChannelFilter* filter = 0;
+       DEBUG_TRACE (DEBUG::MidiDiskstreamIO, string_compose ("MDS::midi_read @ %1 cnt %2\n", start, dur));
 
-       frameoffset_t loop_offset = 0;
+       boost::shared_ptr<MidiTrack> mt = boost::dynamic_pointer_cast<MidiTrack>(_route);
+       MidiChannelFilter* filter = mt ? &mt->playback_filter() : 0;
+       sampleoffset_t loop_offset = 0;
 
        if (!reversed && loc) {
                get_location_times (loc, &loop_start, &loop_end, &loop_length);
@@ -1683,10 +1393,10 @@ DiskReader::midi_read (framepos_t& start, framecnt_t dur, bool reversed)
                if (loc && !reversed) {
 
                        if (!loop_range) {
-                               loop_range = new Evoral::Range<framepos_t> (loop_start, loop_end-1); // inclusive semantics require -1
+                               loop_range = new Evoral::Range<samplepos_t> (loop_start, loop_end-1); // inclusive semantics require -1
                        }
 
-                       /* if we are (seamlessly) looping, ensure that the first frame we read is at the correct
+                       /* if we are (seamlessly) looping, ensure that the first sample we read is at the correct
                           position within the loop.
                        */
 
@@ -1715,12 +1425,12 @@ DiskReader::midi_read (framepos_t& start, framecnt_t dur, bool reversed)
 
                if (midi_playlist()->read (*_midi_buf, effective_start, this_read, loop_range, 0, filter) != this_read) {
                        error << string_compose(
-                                       _("MidiDiskstream %1: cannot read %2 from playlist at frame %3"),
+                                       _("MidiDiskstream %1: cannot read %2 from playlist at sample %3"),
                                        id(), this_read, start) << endmsg;
                        return -1;
                }
 
-               g_atomic_int_add (&_frames_written_to_ringbuffer, this_read);
+               g_atomic_int_add (&_samples_written_to_ringbuffer, this_read);
 
                if (reversed) {
 
@@ -1743,7 +1453,6 @@ DiskReader::midi_read (framepos_t& start, framecnt_t dur, bool reversed)
                }
 
                dur -= this_read;
-               //offset += this_read;
        }
 
        return 0;
@@ -1752,12 +1461,14 @@ DiskReader::midi_read (framepos_t& start, framecnt_t dur, bool reversed)
 int
 DiskReader::refill_midi ()
 {
-       int     ret         = 0;
-       size_t  write_space = _midi_buf->write_space();
-       bool    reversed    = (_visible_speed * _session.transport_speed()) < 0.0f;
+       if (!_playlists[DataType::MIDI]) {
+               return 0;
+       }
+
+       const size_t  write_space = _midi_buf->write_space();
+       const bool reversed    = _session.transport_speed() < 0.0f;
 
-       DEBUG_TRACE (DEBUG::MidiDiskstreamIO, string_compose ("MDS refill, write space = %1 file frame = %2\n",
-                                                             write_space, file_frame));
+       DEBUG_TRACE (DEBUG::DiskIO, string_compose ("MIDI refill, write space = %1 file sample = %2\n", write_space, file_sample[DataType::MIDI]));
 
        /* no space to write */
        if (write_space == 0) {
@@ -1769,25 +1480,44 @@ DiskReader::refill_midi ()
        }
 
        /* at end: nothing to do */
-       if (file_frame == max_framepos) {
+
+       samplepos_t ffm = file_sample[DataType::MIDI];
+
+       if (ffm == max_samplepos) {
                return 0;
        }
 
-       uint32_t frames_read = g_atomic_int_get (&_frames_read_from_ringbuffer);
-       uint32_t frames_written = g_atomic_int_get (&_frames_written_to_ringbuffer);
+       int ret = 0;
+       const uint32_t samples_read = g_atomic_int_get (&_samples_read_from_ringbuffer);
+       const uint32_t samples_written = g_atomic_int_get (&_samples_written_to_ringbuffer);
 
-       if ((frames_read < frames_written) && (frames_written - frames_read) >= midi_readahead) {
+       if ((samples_read < samples_written) && (samples_written - samples_read) >= midi_readahead) {
                return 0;
        }
 
-       framecnt_t to_read = midi_readahead - ((framecnt_t)frames_written - (framecnt_t)frames_read);
+       samplecnt_t to_read = midi_readahead - ((samplecnt_t)samples_written - (samplecnt_t)samples_read);
 
-       to_read = min (to_read, (framecnt_t) (max_framepos - file_frame));
-       to_read = min (to_read, (framecnt_t) write_space);
+       to_read = min (to_read, (samplecnt_t) (max_samplepos - ffm));
+       to_read = min (to_read, (samplecnt_t) write_space);
 
-       if (midi_read (file_frame, to_read, reversed)) {
+       if (midi_read (ffm, to_read, reversed)) {
                ret = -1;
        }
 
+       file_sample[DataType::MIDI] = ffm;
+
        return ret;
 }
+
+void
+DiskReader::set_no_disk_output (bool yn)
+{
+       /* this MUST be called as part of the process call tree, before any
+          disk readers are invoked. We use it when the session needs the
+          transport (and thus effective read position for DiskReaders) to keep
+          advancing as part of syncing up with a transport master, but we
+          don't want any actual disk output yet because we are still not
+          synced.
+       */
+       _no_disk_output = yn;
+}