Towards fixing AU preset invalidation
[ardour.git] / libs / ardour / disk_reader.cc
index c0f31eabe399f388b46f92ede1dae1eaf00e2ab3..ed3e612cf29eed9490b2e37f60895043586475c6 100644 (file)
@@ -17,8 +17,9 @@
 
 */
 
+#include <boost/smart_ptr/scoped_array.hpp>
+
 #include "pbd/enumwriter.h"
-#include "pbd/i18n.h"
 #include "pbd/memento_command.h"
 
 #include "ardour/audioengine.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;
-framecnt_t DiskReader::midi_readahead = 4096;
-bool DiskReader::no_disk_output = false;
+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)
-       , overwrite_frame (0)
-        , overwrite_offset (0)
-        , _pending_overwrite (false)
-        , overwrite_queued (false)
-       , _gui_feed_buffer (AudioEngine::instance()->raw_buffer_size (DataType::MIDI))
+       , overwrite_sample (0)
+       , overwrite_offset (0)
+       , _pending_overwrite (false)
+       , overwrite_queued (false)
+       , _declick_gain (0)
 {
-       file_frame[DataType::AUDIO] = 0;
-       file_frame[DataType::MIDI] = 0;
+       file_sample[DataType::AUDIO] = 0;
+       file_sample[DataType::MIDI] = 0;
 }
 
 DiskReader::~DiskReader ()
@@ -69,21 +71,29 @@ DiskReader::~DiskReader ()
                        _playlists[n]->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;
-               }
+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
@@ -107,8 +117,8 @@ DiskReader::free_working_buffers()
        _gain_buffer          = 0;
 }
 
-framecnt_t
-DiskReader::default_chunk_frames()
+samplecnt_t
+DiskReader::default_chunk_samples()
 {
        return 65536;
 }
@@ -116,7 +126,7 @@ DiskReader::default_chunk_frames()
 bool
 DiskReader::set_name (string const & str)
 {
-       string my_name = X_("playback:");
+       string my_name = X_("player:");
        my_name += str;
 
        if (_name != my_name) {
@@ -126,16 +136,10 @@ DiskReader::set_name (string const & str)
        return true;
 }
 
-void
-DiskReader::set_roll_delay (ARDOUR::framecnt_t nframes)
-{
-       _roll_delay = nframes;
-}
-
 XMLNode&
-DiskReader::state (bool full)
+DiskReader::state ()
 {
-       XMLNode& node (DiskIOProcessor::state (full));
+       XMLNode& node (DiskIOProcessor::state ());
        node.set_property(X_("type"), X_("diskreader"));
        return node;
 }
@@ -153,7 +157,6 @@ DiskReader::set_state (const XMLNode& node, int version)
 void
 DiskReader::realtime_handle_transport_stopped ()
 {
-       realtime_speed_change ();
 }
 
 void
@@ -181,7 +184,7 @@ 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());
 }
 
@@ -237,13 +240,13 @@ DiskReader::use_playlist (DataType dt, boost::shared_ptr<Playlist> playlist)
 }
 
 void
-DiskReader::run (BufferSet& bufs, framepos_t start_frame, framepos_t end_frame,
+DiskReader::run (BufferSet& bufs, samplepos_t start_sample, samplepos_t end_sample,
                  double speed, pframes_t nframes, bool result_required)
 {
        uint32_t n;
        boost::shared_ptr<ChannelList> c = channels.reader();
        ChannelList::iterator chan;
-       frameoffset_t playback_distance;
+       sampleoffset_t disk_samples_to_consume;
        MonitorState ms = _route->monitoring_state ();
 
        if (_active) {
@@ -259,42 +262,45 @@ DiskReader::run (BufferSet& bufs, framepos_t start_frame, framepos_t end_frame,
                }
        }
 
-       if (speed == 0.0 && (ms == MonitoringDisk)) {
-               /* stopped. Don't accidentally pass any data from disk
-                * into our outputs (e.g. via interpolation)
+       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)
                 */
-               bufs.silence (nframes, 0);
                return;
        }
 
-       if (speed != 1.0f && speed != -1.0f) {
-               interpolation.set_speed (speed);
-               midi_interpolation.set_speed (speed);
-               playback_distance = midi_interpolation.distance (nframes);
-               if (speed < 0.0) {
-                       playback_distance = -playback_distance;
-               }
-       } else {
-               playback_distance = nframes;
-       }
-
        BufferSet& scratch_bufs (_session.get_scratch_buffers (bufs.count()));
        const bool still_locating = _session.global_locate_pending();
 
-       if (!result_required || ((ms & MonitoringDisk) == 0) || still_locating) {
+       if (c->empty()) {
+               /* do nothing with audio */
+               goto midi;
+       }
+
+       assert (speed == -1 || speed == 0 || speed == 1);
+
+       if (speed < 0) {
+               disk_samples_to_consume = -nframes;
+       } else if (speed > 0) {
+               disk_samples_to_consume = nframes;
+       } else {
+               disk_samples_to_consume = 0;
+       }
+
+       if (!result_required || ((ms & MonitoringDisk) == 0) || still_locating || _no_disk_output) {
 
                /* no need for actual disk data, just advance read pointer and return */
 
-               if (!still_locating) {
+               if (!still_locating || _no_disk_output) {
                        for (ChannelList::iterator chan = c->begin(); chan != c->end(); ++chan) {
-                               (*chan)->buf->increment_read_ptr (playback_distance);
+                               (*chan)->rbuf->increment_read_ptr (disk_samples_to_consume);
                        }
                }
 
                /* if monitoring disk but locating put silence in the buffers */
 
-               if (still_locating && (ms == MonitoringDisk)) {
-                       bufs.silence (playback_distance, 0);
+               if ((_no_disk_output || still_locating) && (ms == MonitoringDisk)) {
+                       bufs.silence (nframes, 0);
                }
 
        } else {
@@ -325,48 +331,57 @@ DiskReader::run (BufferSet& bufs, framepos_t start_frame, framepos_t end_frame,
                                disk_signal = output.data ();
                        }
 
-                       chaninfo->buf->get_read_vector (&(*chan)->rw_vector);
+                       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 (playback_distance <= (framecnt_t) chaninfo->rw_vector.len[0]) {
+                       if ((speed > 0) && (start_sample != playback_sample)) {
+                               stringstream str;
+                               str << owner()->name() << " playback @ " << start_sample << " not aligned with " << playback_sample << " jump ahead " << (start_sample - playback_sample) << endl;
+                               cerr << str.str();
 
-                               if (fabsf (speed) != 1.0f) {
-                                       (void) interpolation.interpolate (
-                                               n, nframes,
-                                               chaninfo->rw_vector.buf[0],
-                                               disk_signal);
-                               } else if (speed != 0.0) {
-                                       memcpy (disk_signal, chaninfo->rw_vector.buf[0], sizeof (Sample) * playback_distance);
+                               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 {
+                       chaninfo->rbuf->get_read_vector (&(*chan)->rw_vector);
+
+                       if (disk_samples_to_consume <= (samplecnt_t) chaninfo->rw_vector.len[0]) {
+
+                               if (speed != 0.0) {
+                                       memcpy (disk_signal, chaninfo->rw_vector.buf[0], sizeof (Sample) * disk_samples_to_consume);
+                               }
 
-                               const framecnt_t total = chaninfo->rw_vector.len[0] + chaninfo->rw_vector.len[1];
+                       } else {
 
-                               if (playback_distance <= total) {
+                               const samplecnt_t total = chaninfo->rw_vector.len[0] + chaninfo->rw_vector.len[1];
 
-                                       /* We have enough samples, but not in one lump.
-                                        */
+                               if (disk_samples_to_consume <= total) {
 
-                                       if (fabsf (speed) != 1.0f) {
-                                               interpolation.interpolate (n, chaninfo->rw_vector.len[0],
-                                                                          chaninfo->rw_vector.buf[0],
-                                                                          disk_signal);
-                                               disk_signal += chaninfo->rw_vector.len[0];
-                                               interpolation.interpolate (n, playback_distance - chaninfo->rw_vector.len[0],
-                                                                          chaninfo->rw_vector.buf[1],
-                                                                          disk_signal);
-                                       } else if (speed != 0.0) {
-                                               memcpy (disk_signal,
+                                               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],
+                                                       memcpy (disk_signal + chaninfo->rw_vector.len[0],
                                                        chaninfo->rw_vector.buf[1],
-                                                       (playback_distance - chaninfo->rw_vector.len[0]) * sizeof (Sample));
+                                                       (disk_samples_to_consume - chaninfo->rw_vector.len[0]) * sizeof (Sample));
                                        }
 
                                } else {
 
-                                       cerr << _name << " Need " << playback_distance << " total = " << total << endl;
+                                       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));
@@ -377,23 +392,32 @@ DiskReader::run (BufferSet& bufs, framepos_t start_frame, framepos_t end_frame,
                        }
 
                        if (scaling != 1.0f && speed != 0.0) {
-                               apply_gain_to_buffer (disk_signal, nframes, scaling);
+                               apply_gain_to_buffer (disk_signal, disk_samples_to_consume, scaling);
                        }
 
-                       chaninfo->buf->increment_read_ptr (playback_distance);
+                       chaninfo->rbuf->increment_read_ptr (disk_samples_to_consume);
 
-                       if (!no_disk_output && (speed != 0.0) && (ms & MonitoringInput)) {
+                       if (ms & MonitoringInput) {
                                /* mix the disk signal into the input signal (already in bufs) */
-                               mix_buffers_no_gain (output.data(), disk_signal, speed == 0.0 ? nframes : playback_distance);
+                               mix_buffers_no_gain (output.data(), disk_signal, disk_samples_to_consume);
                        }
                }
        }
 
        /* MIDI data handling */
 
-       if (!_session.declick_out_pending()) {
-               if (ms & MonitoringDisk && !still_locating) {
-                       get_midi_playback (bufs.get_midi (0), playback_distance, ms, scratch_bufs, speed, playback_distance);
+  midi:
+       if (/*!_session.declick_out_pending() && */ bufs.count().n_midi() && _midi_buf) {
+               MidiBuffer* dst;
+
+               if (_no_disk_output) {
+                       dst = &scratch_bufs.get_midi(0);
+               } else {
+                       dst = &bufs.get_midi (0);
+               }
+
+               if ((ms & MonitoringDisk) && !still_locating) {
+                       get_midi_playback (*dst, start_sample, end_sample, ms, scratch_bufs, speed, disk_samples_to_consume);
                }
        }
 
@@ -402,23 +426,22 @@ DiskReader::run (BufferSet& bufs, framepos_t start_frame, framepos_t end_frame,
                bool butler_required = false;
 
                if (speed < 0.0) {
-                       playback_sample -= playback_distance;
+                       playback_sample -= disk_samples_to_consume;
                } else {
-                       playback_sample += playback_distance;
+                       playback_sample += disk_samples_to_consume;
                }
 
                if (_playlists[DataType::AUDIO]) {
                        if (!c->empty()) {
                                if (_slaved) {
-                                       if (c->front()->buf->write_space() >= c->front()->buf->bufsize() / 2) {
-                                               DEBUG_TRACE (DEBUG::Butler, string_compose ("%1: slaved, write space = %2 of %3\n", name(), c->front()->buf->write_space(),
-                                                                                           c->front()->buf->bufsize()));
+                                       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 ((framecnt_t) c->front()->buf->write_space() >= _chunk_frames) {
-                                               DEBUG_TRACE (DEBUG::Butler, string_compose ("%1: write space = %2 of %3\n", name(), c->front()->buf->write_space(),
-                                                                                           _chunk_frames));
+                                       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;
                                        }
                                }
@@ -428,16 +451,16 @@ DiskReader::run (BufferSet& bufs, framepos_t start_frame, framepos_t end_frame,
                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
+                       /* 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
@@ -448,13 +471,13 @@ DiskReader::run (BufferSet& bufs, framepos_t start_frame, framepos_t end_frame,
                         *
                         * 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).
+                        * 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 (frames_read - frames_written). ie remove old events
+                        * 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.
@@ -465,8 +488,8 @@ DiskReader::run (BufferSet& bufs, framepos_t start_frame, framepos_t end_frame,
                         * 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) {
+                       if (samples_read <= samples_written) {
+                               if ((samples_written - samples_read) + disk_samples_to_consume < midi_readahead) {
                                        butler_required = true;
                                }
                        } else {
@@ -488,11 +511,11 @@ 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();
        }
 }
 
@@ -505,7 +528,7 @@ DiskReader::overwrite_existing_buffers ()
 
        overwrite_queued = false;
 
-       DEBUG_TRACE (DEBUG::DiskIO, string_compose ("%1 overwriting existing buffers at %2\n", overwrite_frame));
+       DEBUG_TRACE (DEBUG::DiskIO, string_compose ("%1 overwriting existing buffers at %2\n", overwrite_sample));
 
        if (!c->empty ()) {
 
@@ -514,10 +537,10 @@ DiskReader::overwrite_existing_buffers ()
                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)
@@ -525,12 +548,12 @@ 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).
@@ -543,10 +566,10 @@ 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;
                        }
@@ -555,8 +578,8 @@ 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;
                                }
@@ -577,18 +600,18 @@ 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_playlist()->resolve_note_trackers (*_midi_buf, overwrite_sample);
 
-               midi_read (overwrite_frame, _chunk_frames, false);
-               file_frame[DataType::MIDI] = overwrite_frame; // overwrite_frame was adjusted by ::midi_read() to the new position
+               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;
@@ -597,18 +620,20 @@ DiskReader::overwrite_existing_buffers ()
 }
 
 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();
 
+       //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
@@ -616,13 +641,15 @@ DiskReader::seek (framepos_t frame, bool complete_refill)
                reset_tracker ();
        }
 
-       _midi_buf->reset();
-       g_atomic_int_set(&_frames_read_from_ringbuffer, 0);
-       g_atomic_int_set(&_frames_written_to_ringbuffer, 0);
+       if (_midi_buf) {
+               _midi_buf->reset();
+       }
+       g_atomic_int_set(&_samples_read_from_ringbuffer, 0);
+       g_atomic_int_set(&_samples_written_to_ringbuffer, 0);
 
-       playback_sample = frame;
-       file_frame[DataType::AUDIO] = frame;
-       file_frame[DataType::MIDI] = 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
@@ -641,7 +668,7 @@ 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 */
 
@@ -649,27 +676,27 @@ 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;
@@ -689,21 +716,21 @@ 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]) {
@@ -715,7 +742,7 @@ DiskReader::audio_read (Sample* buf, Sample* mixdown_buffer, float* gain_buffer,
 
        if (!reversed) {
 
-               framecnt_t loop_length = 0;
+               samplecnt_t loop_length = 0;
 
                /* Make the use of a Location atomic for this read operation.
 
@@ -725,13 +752,13 @@ 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.
                */
 
@@ -768,7 +795,7 @@ 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;
                }
@@ -805,10 +832,10 @@ 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;
@@ -819,7 +846,7 @@ 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);
 
@@ -841,7 +868,7 @@ 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)
 {
        /* do not read from disk while session is marked as Loading, to avoid
           useless redundant I/O.
@@ -852,15 +879,15 @@ DiskReader::refill_audio (Sample* mixdown_buffer, float* gain_buffer, framecnt_t
        }
 
        int32_t ret = 0;
-       framecnt_t to_read;
+       samplecnt_t to_read;
        RingBufferNPT<Sample>::rw_vector vector;
        bool const reversed = _session.transport_speed() < 0.0f;
-       framecnt_t total_space;
-       framecnt_t zero_fill;
+       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;
+       samplecnt_t ts;
 
        if (c->empty()) {
                return 0;
@@ -874,7 +901,7 @@ 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()));
@@ -892,18 +919,18 @@ 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.
        */
 
-       DEBUG_TRACE (DEBUG::DiskIO, string_compose ("%1: space to refill %2 vs. chunk %3 (speed = %4)\n", name(), total_space, _chunk_frames, _session.transport_speed()));
-       if ((total_space < _chunk_frames) && fabs (_session.transport_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;
        }
 
@@ -912,12 +939,12 @@ 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;
        }
 
-       framepos_t ffa = file_frame[DataType::AUDIO];
+       samplepos_t ffa = file_sample[DataType::AUDIO];
 
        if (reversed) {
 
@@ -928,12 +955,12 @@ DiskReader::refill_audio (Sample* mixdown_buffer, float* gain_buffer, framecnt_t
                        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;
                }
@@ -954,36 +981,36 @@ DiskReader::refill_audio (Sample* mixdown_buffer, float* gain_buffer, framecnt_t
 
        } else {
 
-               if (ffa == 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 (ffa > 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 - ffa);
-                       total_space = max_framepos - ffa;
+                       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 */
 
@@ -1000,7 +1027,7 @@ 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);
 
        DEBUG_TRACE (DEBUG::DiskIO, string_compose ("%1: will refill %2 channels with %3 samples\n", name(), c->size(), total_space));
 
@@ -1012,18 +1039,18 @@ 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
@@ -1040,7 +1067,7 @@ DiskReader::refill_audio (Sample* mixdown_buffer, float* gain_buffer, framecnt_t
                }
 
                ts = total_space;
-               file_frame_tmp = ffa;
+               file_sample_tmp = ffa;
 
                buf1 = vector.buf[0];
                len1 = vector.len[0];
@@ -1048,17 +1075,17 @@ 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;
                }
 
@@ -1071,12 +1098,12 @@ 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) {
@@ -1088,19 +1115,19 @@ DiskReader::refill_audio (Sample* mixdown_buffer, float* gain_buffer, framecnt_t
        // elapsed = g_get_monotonic_time () - before;
        // cerr << '\t' << name() << ": bandwidth = " << (byte_size_for_read / 1048576.0) / (elapsed/1000000.0) << "MB/sec\n";
 
-       file_frame[DataType::AUDIO] = file_frame_tmp;
-       assert (file_frame[DataType::AUDIO] >= 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
@@ -1117,8 +1144,8 @@ DiskReader::playlist_ranges_moved (list< Evoral::RangeMove<framepos_t> > const &
 
        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));
@@ -1145,11 +1172,11 @@ DiskReader::playlist_ranges_moved (list< Evoral::RangeMove<framepos_t> > const &
                 }
         }
        /* move processor automation */
-        _route->foreach_processor (boost::bind (&DiskReader::move_processor_automation, this, _1, movements_frames));
+        _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) {
@@ -1157,7 +1184,7 @@ 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));
        }
 
@@ -1180,20 +1207,12 @@ 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 ()
 {
-       _midi_buf->reset_tracker ();
+       if (_midi_buf) {
+               _midi_buf->reset_tracker ();
+       }
 
        boost::shared_ptr<MidiPlaylist> mp (midi_playlist());
 
@@ -1203,9 +1222,11 @@ 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);
+       if (_midi_buf) {
+               _midi_buf->resolve_tracker(buffer, time);
+       }
 
        boost::shared_ptr<MidiPlaylist> mp (midi_playlist());
 
@@ -1218,25 +1239,28 @@ DiskReader::resolve_tracker (Evoral::EventSink<framepos_t>& buffer, framepos_t t
  *  so that an event at playback_sample has time = 0
  */
 void
-DiskReader::get_midi_playback (MidiBuffer& dst, framecnt_t nframes, MonitorState ms, BufferSet& scratch_bufs, double speed, framecnt_t playback_distance)
+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)
 {
        MidiBuffer* target;
+       samplepos_t nframes = end_sample - start_sample;
+
+       assert (_midi_buf);
 
        if ((ms & MonitoringInput) == 0) {
-               dst.clear();
+               /* Route::process_output_buffers() clears the buffer as-needed */
                target = &dst;
        } else {
                target = &scratch_bufs.get_midi (0);
        }
 
        if (ms & MonitoringDisk) {
-               /* no disk data needed */
+               /* disk data needed */
 
-               Location* loc = loop_location;
+               Location* loc = _loop_location;
 
                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,
+                                    _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()));
 
                //cerr << "======== PRE ========\n";
@@ -1246,10 +1270,10 @@ DiskReader::get_midi_playback (MidiBuffer& dst, framecnt_t nframes, MonitorState
                size_t events_read = 0;
 
                if (loc) {
-                       framepos_t effective_start;
+                       samplepos_t effective_start;
 
-                       Evoral::Range<framepos_t> loop_range (loc->start(), loc->end() - 1);
-                       effective_start = loop_range.squish (playback_sample);
+                       Evoral::Range<samplepos_t> loop_range (loc->start(), loc->end() - 1);
+                       effective_start = loop_range.squish (start_sample);
 
                        DEBUG_TRACE (DEBUG::MidiDiskstreamIO, string_compose ("looped, effective start adjusted to %1\n", effective_start));
 
@@ -1270,7 +1294,7 @@ DiskReader::get_midi_playback (MidiBuffer& dst, framecnt_t nframes, MonitorState
                                   for the 2nd read
                                */
 
-                               framecnt_t first, second;
+                               samplecnt_t first, second;
 
                                first = loc->end() - effective_start;
                                second = nframes - first;
@@ -1296,12 +1320,12 @@ DiskReader::get_midi_playback (MidiBuffer& dst, framecnt_t nframes, MonitorState
                                events_read = _midi_buf->read (*target, effective_start, effective_start + nframes);
                        }
                } else {
-                       const size_t n_skipped = _midi_buf->skip_to (playback_sample);
+                       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)", playback_sample, playback_sample + nframes, nframes));
-                       events_read = _midi_buf->read (*target, playback_sample, playback_sample + nframes);
+                       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 (
@@ -1311,14 +1335,16 @@ DiskReader::get_midi_playback (MidiBuffer& dst, framecnt_t nframes, MonitorState
                                     _midi_buf->get_read_ptr(), _midi_buf->get_write_ptr()));
        }
 
-       g_atomic_int_add (&_frames_read_from_ringbuffer, nframes);
+       g_atomic_int_add (&_samples_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();
-                       *tme = (*tme) * nframes / playback_distance;
+                       // 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;
                }
        }
 
@@ -1326,28 +1352,46 @@ DiskReader::get_midi_playback (MidiBuffer& dst, framecnt_t nframes, MonitorState
                dst.merge_from (*target, nframes);
        }
 
-       //cerr << "======== POST ========\n";
-       //_midi_buf->dump (cerr);
-       //cerr << "----------------\n";
+#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);
+
+       assert(_midi_buf);
 
        DEBUG_TRACE (DEBUG::MidiDiskstreamIO, string_compose ("MDS::midi_read @ %1 cnt %2\n", start, dur));
 
        boost::shared_ptr<MidiTrack> mt = boost::dynamic_pointer_cast<MidiTrack>(_route);
        MidiChannelFilter* filter = mt ? &mt->playback_filter() : 0;
-       frameoffset_t loop_offset = 0;
+       sampleoffset_t loop_offset = 0;
 
        if (!reversed && loc) {
                get_location_times (loc, &loop_start, &loop_end, &loop_length);
@@ -1360,10 +1404,10 @@ 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.
                        */
 
@@ -1392,12 +1436,12 @@ 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) {
 
@@ -1420,7 +1464,6 @@ DiskReader::midi_read (framepos_t& start, framecnt_t dur, bool reversed)
                }
 
                dur -= this_read;
-               //offset += this_read;
        }
 
        return 0;
@@ -1429,14 +1472,14 @@ DiskReader::midi_read (framepos_t& start, framecnt_t dur, bool reversed)
 int
 DiskReader::refill_midi ()
 {
-       if (!_playlists[DataType::MIDI]) {
+       if (!_playlists[DataType::MIDI] || !_midi_buf) {
                return 0;
        }
 
-       size_t  write_space = _midi_buf->write_space();
+       const size_t  write_space = _midi_buf->write_space();
        const bool reversed    = _session.transport_speed() < 0.0f;
 
-       DEBUG_TRACE (DEBUG::DiskIO, string_compose ("MIDI refill, write space = %1 file frame = %2\n", write_space, file_frame[DataType::MIDI]));
+       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) {
@@ -1449,30 +1492,30 @@ DiskReader::refill_midi ()
 
        /* at end: nothing to do */
 
-       framepos_t ffm = file_frame[DataType::MIDI];
+       samplepos_t ffm = file_sample[DataType::MIDI];
 
-       if (ffm == max_framepos) {
+       if (ffm == max_samplepos) {
                return 0;
        }
 
        int ret = 0;
-       const uint32_t frames_read = g_atomic_int_get (&_frames_read_from_ringbuffer);
-       const uint32_t frames_written = g_atomic_int_get (&_frames_written_to_ringbuffer);
+       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 - ffm));
-       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 (ffm, to_read, reversed)) {
                ret = -1;
        }
 
-       file_frame[DataType::MIDI] = ffm;
+       file_sample[DataType::MIDI] = ffm;
 
        return ret;
 }
@@ -1487,6 +1530,5 @@ DiskReader::set_no_disk_output (bool yn)
           don't want any actual disk output yet because we are still not
           synced.
        */
-       no_disk_output = yn;
+       _no_disk_output = yn;
 }
-