Fix mute of MIDI tracks with channel forcing.

This moves MIDI channel filtering into a reusable class and moves filtering to
the source, rather than modifying the buffer afterwards.  This is necessary so
that the playlist trackers reflect the emitted notes (and thus are able to stop
them in situations like mute).

As a perk, this is also faster because events are just dropped on read, rather
than pushed into a buffer then later removed (which is very slow).

Really hammering on mute or solo still seems to produce stuck notes
occasionally (perhaps related to multiple-on warnings).  I am not yet sure why,
but occasional beats always.

19 files changed, 359 insertions, 203 deletions

diff --git a/gtk2_ardour/midi_channel_selector.cc b/gtk2_ardour/midi_channel_selector.cc
index 4884d72328..1895b5c52f 100644
--- a/gtk2_ardour/midi_channel_selector.cc
+++ b/gtk2_ardour/midi_channel_selector.cc
@@ -27,6 +27,7 @@
 #include <gtkmm/table.h>
 
 #include "pbd/compose.h"
+#include "pbd/ffs.h"
 
 #include "gtkmm2ext/gtk_ui.h"
 #include "gtkmm2ext/gui_thread.h"
@@ -343,10 +344,10 @@ MidiChannelSelectorWindow::MidiChannelSelectorWindow (boost::shared_ptr<MidiTrac
 	playback_mask_changed ();
 	capture_mask_changed ();
 
-	track->PlaybackChannelMaskChanged.connect (*this, MISSING_INVALIDATOR, boost::bind (&MidiChannelSelectorWindow::playback_mask_changed, this), gui_context());
-	track->PlaybackChannelModeChanged.connect (*this, MISSING_INVALIDATOR, boost::bind (&MidiChannelSelectorWindow::playback_mode_changed, this), gui_context());
-	track->CaptureChannelMaskChanged.connect (*this, MISSING_INVALIDATOR, boost::bind (&MidiChannelSelectorWindow::capture_mask_changed, this), gui_context());
-	track->CaptureChannelModeChanged.connect (*this, MISSING_INVALIDATOR, boost::bind (&MidiChannelSelectorWindow::capture_mode_changed, this), gui_context());
+	track->playback_filter().ChannelMaskChanged.connect (*this, MISSING_INVALIDATOR, boost::bind (&MidiChannelSelectorWindow::playback_mask_changed, this), gui_context());
+	track->playback_filter().ChannelModeChanged.connect (*this, MISSING_INVALIDATOR, boost::bind (&MidiChannelSelectorWindow::playback_mode_changed, this), gui_context());
+	track->capture_filter().ChannelMaskChanged.connect (*this, MISSING_INVALIDATOR, boost::bind (&MidiChannelSelectorWindow::capture_mask_changed, this), gui_context());
+	track->capture_filter().ChannelModeChanged.connect (*this, MISSING_INVALIDATOR, boost::bind (&MidiChannelSelectorWindow::capture_mode_changed, this), gui_context());
 }
 
 MidiChannelSelectorWindow::~MidiChannelSelectorWindow()
diff --git a/gtk2_ardour/midi_region_view.cc b/gtk2_ardour/midi_region_view.cc
index 7bed675ac3..eed9017d0d 100644
--- a/gtk2_ardour/midi_region_view.cc
+++ b/gtk2_ardour/midi_region_view.cc
@@ -299,7 +299,7 @@ MidiRegionView::init (bool wfd)
 
 	group->raise_to_top();
 
-	midi_view()->midi_track()->PlaybackChannelModeChanged.connect (_channel_mode_changed_connection, invalidator (*this),
+	midi_view()->midi_track()->playback_filter().ChannelModeChanged.connect (_channel_mode_changed_connection, invalidator (*this),
 								       boost::bind (&MidiRegionView::midi_channel_mode_changed, this),
 								       gui_context ());
 
diff --git a/gtk2_ardour/midi_time_axis.cc b/gtk2_ardour/midi_time_axis.cc
index bbf0473ded..be475216c1 100644
--- a/gtk2_ardour/midi_time_axis.cc
+++ b/gtk2_ardour/midi_time_axis.cc
@@ -243,18 +243,22 @@ MidiTimeAxisView::set_route (boost::shared_ptr<Route> rt)
 		_view->RegionViewAdded.connect (
 			sigc::mem_fun(*this, &MidiTimeAxisView::region_view_added));
 
-		midi_track()->PlaybackChannelModeChanged.connect (*this, invalidator (*this),
-								  boost::bind (&MidiTimeAxisView::playback_channel_mode_changed, this),
-								  gui_context());
-		midi_track()->PlaybackChannelMaskChanged.connect (*this, invalidator (*this),
-								  boost::bind (&MidiTimeAxisView::playback_channel_mode_changed, this),
-								  gui_context());
-		midi_track()->CaptureChannelModeChanged.connect (*this, invalidator (*this),
-								  boost::bind (&MidiTimeAxisView::capture_channel_mode_changed, this),
-								  gui_context());
-		midi_track()->CaptureChannelMaskChanged.connect (*this, invalidator (*this),
-								  boost::bind (&MidiTimeAxisView::capture_channel_mode_changed, this),
-								  gui_context());
+		midi_track()->playback_filter().ChannelModeChanged.connect (
+			*this, invalidator (*this),
+			boost::bind (&MidiTimeAxisView::playback_channel_mode_changed, this),
+			gui_context());
+		midi_track()->playback_filter().ChannelMaskChanged.connect (
+			*this, invalidator (*this),
+			boost::bind (&MidiTimeAxisView::playback_channel_mode_changed, this),
+			gui_context());
+		midi_track()->capture_filter().ChannelModeChanged.connect (
+			*this, invalidator (*this),
+			boost::bind (&MidiTimeAxisView::capture_channel_mode_changed, this),
+			gui_context());
+		midi_track()->capture_filter().ChannelMaskChanged.connect (
+			*this, invalidator (*this),
+			boost::bind (&MidiTimeAxisView::capture_channel_mode_changed, this),
+			gui_context());
 
 		playback_channel_mode_changed ();
 		capture_channel_mode_changed ();
diff --git a/libs/ardour/ardour/midi_channel_filter.h b/libs/ardour/ardour/midi_channel_filter.h
new file mode 100644
index 0000000000..934b369b8c
--- /dev/null
+++ b/libs/ardour/ardour/midi_channel_filter.h
@@ -0,0 +1,97 @@
+/*
+    Copyright (C) 2006-2015 Paul Davis
+    Author: David Robillard
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+*/
+
+#ifndef __ardour_channel_filter_h__
+#define __ardour_channel_filter_h__
+
+#include <stdint.h>
+
+#include <glib.h>
+
+#include "ardour/types.h"
+#include "pbd/signals.h"
+
+namespace ARDOUR
+{
+
+class BufferSet;
+
+/** Filter/mapper for MIDI channels.
+ *
+ * Channel mapping is configured by setting a mode and "mask", where the
+ * meaning of the mask depends on the mode.
+ *
+ * If mode is FilterChannels, each mask bit represents a midi channel (bit 0 =
+ * channel 0, bit 1 = channel 1, ...).  Only events whose channel corresponds
+ * to a 1 bit will be passed.
+ *
+ * If mode is ForceChannel, mask is simply a channel number which all events
+ * will be forced to.
+ */
+class LIBARDOUR_API MidiChannelFilter
+{
+public:
+	MidiChannelFilter();
+
+	/** Filter `bufs` in-place. */
+	void filter(BufferSet& bufs);
+
+	/** Filter/map a MIDI message by channel.
+	 *
+	 * May modify the channel in `buf` if necessary.
+	 *
+	 * @return true if this event should be filtered out.
+	 */
+	bool filter(uint8_t* buf, uint32_t len);
+
+	/** Atomically set the channel mode and corresponding mask.
+	 * @return true iff configuration changed.
+	 */
+	bool set_channel_mode(ChannelMode mode, uint16_t mask);
+
+	/** Atomically set the channel mask for the current mode.
+	 * @return true iff configuration changed.
+	 */
+	bool set_channel_mask(uint16_t mask);
+
+	/** Atomically get both the channel mode and mask. */
+	void get_mode_and_mask(ChannelMode* mode, uint16_t* mask) const {
+		const uint32_t mm = g_atomic_int_get(&_mode_mask);
+		*mode = static_cast<ChannelMode>((mm & 0xFFFF0000) >> 16);
+		*mask = (mm & 0x0000FFFF);
+	}
+
+	ChannelMode get_channel_mode() const {
+		return static_cast<ChannelMode>((g_atomic_int_get(&_mode_mask) & 0xFFFF0000) >> 16);
+	}
+
+	uint16_t get_channel_mask() const {
+		return g_atomic_int_get(&_mode_mask) & 0x0000FFFF;
+	}
+
+	PBD::Signal0<void> ChannelMaskChanged;
+	PBD::Signal0<void> ChannelModeChanged;
+
+private:
+	uint32_t _mode_mask;  ///< 16 bits mode, 16 bits mask
+};
+
+} /* namespace ARDOUR */
+
+#endif /* __ardour_channel_filter_h__ */
diff --git a/libs/ardour/ardour/midi_playlist.h b/libs/ardour/ardour/midi_playlist.h
index 614a5e1c1f..cb07bc1820 100644
--- a/libs/ardour/ardour/midi_playlist.h
+++ b/libs/ardour/ardour/midi_playlist.h
@@ -42,6 +42,7 @@ namespace ARDOUR
 {
 
 class BeatsFramesConverter;
+class MidiChannelFilter;
 class MidiRegion;
 class Session;
 class Source;
@@ -77,7 +78,8 @@ public:
 	framecnt_t read (Evoral::EventSink<framepos_t>& buf,
 	                 framepos_t                     start,
 	                 framecnt_t                     cnt,
-	                 uint32_t                       chan_n = 0);
+	                 uint32_t                       chan_n = 0,
+	                 MidiChannelFilter*             filter = NULL);
 
 	int set_state (const XMLNode&, int version);
 
diff --git a/libs/ardour/ardour/midi_playlist_source.h b/libs/ardour/ardour/midi_playlist_source.h
index 6633be3c9e..12c184d7b5 100644
--- a/libs/ardour/ardour/midi_playlist_source.h
+++ b/libs/ardour/ardour/midi_playlist_source.h
@@ -65,7 +65,8 @@ protected:
 	                          framepos_t                     position,
 	                          framepos_t                     start,
 	                          framecnt_t                     cnt,
-	                          MidiStateTracker*              tracker) const;
+	                          MidiStateTracker*              tracker,
+	                          MidiChannelFilter*             filter) const;
 
 	framecnt_t write_unlocked (const Lock&                 lock,
 	                           MidiRingBuffer<framepos_t>& dst,
diff --git a/libs/ardour/ardour/midi_region.h b/libs/ardour/ardour/midi_region.h
index f7e6c97ea0..87e89c695b 100644
--- a/libs/ardour/ardour/midi_region.h
+++ b/libs/ardour/ardour/midi_region.h
@@ -43,13 +43,14 @@ template<typename Time> class EventSink;
 
 namespace ARDOUR {
 
-class Route;
-class Playlist;
-class Session;
+class MidiChannelFilter;
 class MidiFilter;
 class MidiModel;
 class MidiSource;
 class MidiStateTracker;
+class Playlist;
+class Route;
+class Session;
 
 template<typename T> class MidiRingBuffer;
 
@@ -74,7 +75,8 @@ class LIBARDOUR_API MidiRegion : public Region
 	                    framecnt_t dur,
 	                    uint32_t  chan_n = 0,
 	                    NoteMode  mode = Sustained,
-	                    MidiStateTracker* tracker = 0) const;
+	                    MidiStateTracker* tracker = 0,
+	                    MidiChannelFilter* filter = 0) const;
 
 	framecnt_t master_read_at (MidiRingBuffer<framepos_t>& dst,
 	                           framepos_t position,
@@ -121,7 +123,8 @@ class LIBARDOUR_API MidiRegion : public Region
 	                     framecnt_t dur,
 	                     uint32_t chan_n = 0,
 	                     NoteMode mode = Sustained,
-	                     MidiStateTracker* tracker = 0) const;
+	                     MidiStateTracker* tracker = 0,
+	                     MidiChannelFilter* filter = 0) const;
 
 	void register_properties ();
 	void post_set (const PBD::PropertyChange&);
diff --git a/libs/ardour/ardour/midi_source.h b/libs/ardour/ardour/midi_source.h
index 156f3dbfa0..6a55398ca9 100644
--- a/libs/ardour/ardour/midi_source.h
+++ b/libs/ardour/ardour/midi_source.h
@@ -34,6 +34,7 @@
 
 namespace ARDOUR {
 
+class MidiChannelFilter;
 class MidiStateTracker;
 class MidiModel;
 
@@ -77,6 +78,7 @@ class LIBARDOUR_API MidiSource : virtual public Source, public boost::enable_sha
 	                              framepos_t                         start,
 	                              framecnt_t                         cnt,
 	                              MidiStateTracker*                  tracker,
+	                              MidiChannelFilter*                 filter,
 	                              const std::set<Evoral::Parameter>& filtered) const;
 
 	/** Write data from a MidiRingBuffer to this source.
@@ -192,7 +194,8 @@ class LIBARDOUR_API MidiSource : virtual public Source, public boost::enable_sha
 	                                  framepos_t                     position,
 	                                  framepos_t                     start,
 	                                  framecnt_t                     cnt,
-	                                  MidiStateTracker*              tracker) const = 0;
+	                                  MidiStateTracker*              tracker,
+	                                  MidiChannelFilter*             filter) const = 0;
 
 	/** Write data to this source from a MidiRingBuffer.
 	 *  @param source Buffer to read from.
diff --git a/libs/ardour/ardour/midi_track.h b/libs/ardour/ardour/midi_track.h
index a12a0c6087..f2542f0f6b 100644
--- a/libs/ardour/ardour/midi_track.h
+++ b/libs/ardour/ardour/midi_track.h
@@ -20,10 +20,9 @@
 #ifndef __ardour_midi_track_h__
 #define __ardour_midi_track_h__
 
-#include "pbd/ffs.h"
-
-#include "ardour/track.h"
+#include "ardour/midi_channel_filter.h"
 #include "ardour/midi_ring_buffer.h"
+#include "ardour/track.h"
 
 namespace ARDOUR
 {
@@ -109,38 +108,22 @@ public:
 
 	boost::shared_ptr<SMFSource> write_source (uint32_t n = 0);
 
-	/** Channel filtering mode.
-	 * @param mask If mode is FilterChannels, each bit represents a midi channel:
-	 *     bit 0 = channel 0, bit 1 = channel 1 etc. the read and write methods will only
-	 *     process events whose channel bit is 1.
-	 *     If mode is ForceChannel, mask is simply a channel number which all events will
-	 *     be forced to while reading.
-	 */
+	/* Configure capture/playback channels (see MidiChannelFilter). */
 	void set_capture_channel_mode (ChannelMode mode, uint16_t mask);
 	void set_playback_channel_mode (ChannelMode mode, uint16_t mask);
 	void set_playback_channel_mask (uint16_t mask);
 	void set_capture_channel_mask (uint16_t mask);
 
-	ChannelMode get_playback_channel_mode() const {
-		return static_cast<ChannelMode>((g_atomic_int_get(&_playback_channel_mask) & 0xffff0000) >> 16);
-	}
-	uint16_t get_playback_channel_mask() const {
-		return g_atomic_int_get(&_playback_channel_mask) & 0x0000ffff;
-	}
-	ChannelMode get_capture_channel_mode() const {
-		return static_cast<ChannelMode>((g_atomic_int_get(&_capture_channel_mask) & 0xffff0000) >> 16);
-	}
-	uint16_t get_capture_channel_mask() const {
-		return g_atomic_int_get(&_capture_channel_mask) & 0x0000ffff;
-	}
+	ChannelMode get_playback_channel_mode() const { return _playback_filter.get_channel_mode(); }
+	ChannelMode get_capture_channel_mode()  const { return _capture_filter.get_channel_mode(); }
+	uint16_t    get_playback_channel_mask() const { return _playback_filter.get_channel_mask(); }
+	uint16_t    get_capture_channel_mask()  const { return _capture_filter.get_channel_mask(); }
+
+	MidiChannelFilter& playback_filter() { return _playback_filter; }
+	MidiChannelFilter& capture_filter()  { return _capture_filter; }
 
 	boost::shared_ptr<MidiPlaylist> midi_playlist ();
 
-	PBD::Signal0<void> PlaybackChannelMaskChanged;
-	PBD::Signal0<void> PlaybackChannelModeChanged;
-	PBD::Signal0<void> CaptureChannelMaskChanged;
-	PBD::Signal0<void> CaptureChannelModeChanged;
-    
 	PBD::Signal1<void, boost::weak_ptr<MidiSource> > DataRecorded;
 	boost::shared_ptr<MidiBuffer> get_gui_feed_buffer () const;
 
@@ -162,8 +145,8 @@ private:
 	NoteMode                   _note_mode;
 	bool                       _step_editing;
 	bool                       _input_active;
-	uint32_t                   _playback_channel_mask; // 16 bits mode, 16 bits mask
-	uint32_t                   _capture_channel_mask; // 16 bits mode, 16 bits mask
+	MidiChannelFilter          _playback_filter;
+	MidiChannelFilter          _capture_filter;
 
 	virtual boost::shared_ptr<Diskstream> diskstream_factory (XMLNode const &);
 	
@@ -186,32 +169,6 @@ private:
 
 	/** Update automation controls to reflect any changes in buffers. */
 	void update_controls (const BufferSet& bufs);
-
-	void filter_channels (BufferSet& bufs, ChannelMode mode, uint32_t mask); 
-
-/* if mode is ForceChannel, force mask to the lowest set channel or 1 if no
- * channels are set.
- */
-#define force_mask(mode,mask) (((mode) == ForceChannel) ? (((mask) ? (1<<(PBD::ffs((mask))-1)) : 1)) : mask)
-
-	void _set_playback_channel_mode(ChannelMode mode, uint16_t mask) {
-		mask = force_mask (mode, mask);
-		g_atomic_int_set(&_playback_channel_mask, (uint32_t(mode) << 16) | uint32_t(mask));
-	}
-	void _set_playback_channel_mask (uint16_t mask) {
-		mask = force_mask (get_playback_channel_mode(), mask);
-		g_atomic_int_set(&_playback_channel_mask, (uint32_t(get_playback_channel_mode()) << 16) | uint32_t(mask));
-	}
-	void _set_capture_channel_mode(ChannelMode mode, uint16_t mask) {
-		mask = force_mask (mode, mask);
-		g_atomic_int_set(&_capture_channel_mask, (uint32_t(mode) << 16) | uint32_t(mask));
-	}
-	void _set_capture_channel_mask (uint16_t mask) {
-		mask = force_mask (get_capture_channel_mode(), mask);
-		g_atomic_int_set(&_capture_channel_mask, (uint32_t(get_capture_channel_mode()) << 16) | uint32_t(mask));
-	}
-
-#undef force_mask
 };
 
 } /* namespace ARDOUR*/
diff --git a/libs/ardour/ardour/smf_source.h b/libs/ardour/ardour/smf_source.h
index 29c6403694..d088f2d867 100644
--- a/libs/ardour/ardour/smf_source.h
+++ b/libs/ardour/ardour/smf_source.h
@@ -93,7 +93,8 @@ public:
 	                          framepos_t                     position,
 	                          framepos_t                     start,
 	                          framecnt_t                     cnt,
-	                          MidiStateTracker*              tracker) const;
+	                          MidiStateTracker*              tracker,
+	                          MidiChannelFilter*             filter) const;
 
 	framecnt_t write_unlocked (const Lock&                 lock,
 	                           MidiRingBuffer<framepos_t>& src,
diff --git a/libs/ardour/midi_channel_filter.cc b/libs/ardour/midi_channel_filter.cc
new file mode 100644
index 0000000000..40658802e5
--- /dev/null
+++ b/libs/ardour/midi_channel_filter.cc
@@ -0,0 +1,143 @@
+/*
+    Copyright (C) 2006-2015 Paul Davis
+    Author: David Robillard
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+*/
+
+#include "ardour/buffer_set.h"
+#include "ardour/midi_buffer.h"
+#include "ardour/midi_channel_filter.h"
+#include "pbd/ffs.h"
+
+namespace ARDOUR {
+
+MidiChannelFilter::MidiChannelFilter()
+	: _mode_mask(0x0000FFFF)
+{}
+
+void
+MidiChannelFilter::filter(BufferSet& bufs)
+{
+	ChannelMode mode;
+	uint16_t    mask;
+	get_mode_and_mask(&mode, &mask);
+
+	if (mode == AllChannels) {
+		return;
+	}
+
+	MidiBuffer& buf = bufs.get_midi(0);
+
+	for (MidiBuffer::iterator e = buf.begin(); e != buf.end(); ) {
+		Evoral::MIDIEvent<framepos_t> ev(*e, false);
+
+		if (ev.is_channel_event()) {
+			switch (mode) {
+			case FilterChannels:
+				if (0 == ((1 << ev.channel()) & mask)) {
+					e = buf.erase (e);
+				} else {
+					++e;
+				}
+				break;
+			case ForceChannel:
+				ev.set_channel(PBD::ffs(mask) - 1);
+				++e;
+				break;
+			case AllChannels:
+				/* handled by the opening if() */
+				++e;
+				break;
+			}
+		} else {
+			++e;
+		}
+	}
+}
+
+bool
+MidiChannelFilter::filter(uint8_t* buf, uint32_t len)
+{
+	ChannelMode mode;
+	uint16_t    mask;
+	get_mode_and_mask(&mode, &mask);
+
+	const uint8_t type             = buf[0] & 0xF0;
+	const bool    is_channel_event = (0x80 <= type) && (type <= 0xE0);
+	if (!is_channel_event) {
+		return false;
+	}
+
+	const uint8_t channel = buf[0] & 0x0F;
+	switch (mode) {
+	case AllChannels:
+		return false;
+	case FilterChannels:
+		return !((1 << channel) & mask);
+	case ForceChannel:
+		buf[0] = (0xF0 & buf[0]) | (0x0F & (PBD::ffs(mask) - 1));
+		return false;
+	}
+
+	return false;
+}
+
+/** If mode is ForceChannel, force mask to the lowest set channel or 1 if no
+ *  channels are set.
+ */
+static inline uint16_t
+force_mask(const ChannelMode mode, const uint16_t mask)
+{
+	return ((mode == ForceChannel)
+	        ? (mask ? (1 << (PBD::ffs(mask) - 1)) : 1)
+	        : mask);
+}
+
+bool
+MidiChannelFilter::set_channel_mode(ChannelMode mode, uint16_t mask)
+{
+	ChannelMode old_mode;
+	uint16_t    old_mask;
+	get_mode_and_mask(&old_mode, &old_mask);
+
+	if (old_mode != mode || old_mask != mask) {
+		mask = force_mask(mode, mask);
+		g_atomic_int_set(&_mode_mask, (uint32_t(mode) << 16) | uint32_t(mask));
+		ChannelModeChanged();
+		return true;
+	}
+
+	return false;
+}
+
+bool
+MidiChannelFilter::set_channel_mask(uint16_t mask)
+{
+	ChannelMode mode;
+	uint16_t    old_mask;
+	get_mode_and_mask(&mode, &old_mask);
+
+	if (old_mask != mask) {
+		mask = force_mask(mode, mask);
+		g_atomic_int_set(&_mode_mask, (uint32_t(mode) << 16) | uint32_t(mask));
+		ChannelMaskChanged();
+		return true;
+	}
+
+	return false;
+}
+
+} /* namespace ARDOUR */
diff --git a/libs/ardour/midi_diskstream.cc b/libs/ardour/midi_diskstream.cc
index f6ba10342a..e8b23b3431 100644
--- a/libs/ardour/midi_diskstream.cc
+++ b/libs/ardour/midi_diskstream.cc
@@ -403,17 +403,10 @@ MidiDiskstream::process (BufferSet& bufs, framepos_t transport_frame, pframes_t
 	}
 
 	if (nominally_recording || rec_nframes) {
-
-		// Pump entire port buffer into the ring buffer (FIXME: split cycles?)
-		MidiBuffer& buf = sp->get_midi_buffer(nframes);
-		ChannelMode mode = AllChannels;
-		uint32_t mask = 0xffff;
-
-		MidiTrack * mt = dynamic_cast<MidiTrack*> (_track);
-		if (mt) {
-			mode = mt->get_capture_channel_mode ();
-			mask = mt->get_capture_channel_mask ();
-		}
+		// Pump entire port buffer into the ring buffer (TODO: split cycles?)
+		MidiBuffer&        buf    = sp->get_midi_buffer(nframes);
+		MidiTrack*         mt     = dynamic_cast<MidiTrack*>(_track);
+		MidiChannelFilter* filter = mt ? &mt->capture_filter() : NULL;
 
 		for (MidiBuffer::iterator i = buf.begin(); i != buf.end(); ++i) {
 			Evoral::MIDIEvent<MidiBuffer::TimeType> ev(*i, false);
@@ -447,31 +440,12 @@ MidiDiskstream::process (BufferSet& bufs, framepos_t transport_frame, pframes_t
 			const framecnt_t loop_offset = _num_captured_loops * loop_length;
 			const framepos_t event_time = transport_frame + loop_offset - _accumulated_capture_offset + ev.time();
 			if (event_time < 0 || event_time < first_recordable_frame) {
+				/* Event out of range, skip */
 				continue;
 			}
-			switch (mode) {
-			case AllChannels:
-				_capture_buf->write(event_time,
-						    ev.type(), ev.size(), ev.buffer());
-				break;
-			case FilterChannels:
-				if (ev.is_channel_event()) {
-					if ((1<<ev.channel()) & mask) {
-						_capture_buf->write(event_time,
-								    ev.type(), ev.size(), ev.buffer());
-					}
-				} else {
-					_capture_buf->write(event_time,
-							    ev.type(), ev.size(), ev.buffer());
-				}
-				break;
-			case ForceChannel:
-				if (ev.is_channel_event()) {
-					ev.set_channel (PBD::ffs(mask) - 1);
-				}
-				_capture_buf->write(event_time,
-						    ev.type(), ev.size(), ev.buffer());
-				break;
+
+			if (!filter || !filter->filter(ev.buffer(), ev.size())) {
+				_capture_buf->write(event_time, ev.type(), ev.size(), ev.buffer());
 			}
 		}
 		g_atomic_int_add(const_cast<gint*>(&_frames_pending_write), nframes);
@@ -736,6 +710,9 @@ MidiDiskstream::read (framepos_t& start, framecnt_t dur, bool reversed)
 	framecnt_t loop_length = 0;
 	Location*  loc         = 0;
 
+	MidiTrack*         mt     = dynamic_cast<MidiTrack*>(_track);
+	MidiChannelFilter* filter = mt ? &mt->playback_filter() : NULL;
+
 	if (!reversed) {
 
 		loc = loop_location;
@@ -772,7 +749,7 @@ MidiDiskstream::read (framepos_t& start, framecnt_t dur, bool reversed)
 
 		this_read = min(dur,this_read);
 
-		if (midi_playlist()->read (*_playback_buf, start, this_read) != this_read) {
+		if (midi_playlist()->read (*_playback_buf, start, this_read, 0, filter) != this_read) {
 			error << string_compose(
 					_("MidiDiskstream %1: cannot read %2 from playlist at frame %3"),
 					id(), this_read, start) << endmsg;
diff --git a/libs/ardour/midi_playlist.cc b/libs/ardour/midi_playlist.cc
index 398234e2ba..c0badf7a0d 100644
--- a/libs/ardour/midi_playlist.cc
+++ b/libs/ardour/midi_playlist.cc
@@ -106,7 +106,11 @@ struct EventsSortByTimeAndType {
 };
 
 framecnt_t
-MidiPlaylist::read (Evoral::EventSink<framepos_t>& dst, framepos_t start, framecnt_t dur, unsigned chan_n)
+MidiPlaylist::read (Evoral::EventSink<framepos_t>& dst,
+                    framepos_t                     start,
+                    framecnt_t                     dur,
+                    unsigned                       chan_n,
+                    MidiChannelFilter*             filter)
 {
 	typedef pair<MidiStateTracker*,framepos_t> TrackerInfo;
 
@@ -185,7 +189,7 @@ MidiPlaylist::read (Evoral::EventSink<framepos_t>& dst, framepos_t start, framec
 		}
 
 		/* Read from region into target. */
-		mr->read_at (tgt, start, dur, chan_n, _note_mode, &tracker->tracker);
+		mr->read_at (tgt, start, dur, chan_n, _note_mode, &tracker->tracker, filter);
 		DEBUG_TRACE (DEBUG::MidiPlaylistIO,
 		             string_compose ("\tPost-read: %1 active notes\n", tracker->tracker.on()));
 
diff --git a/libs/ardour/midi_playlist_source.cc b/libs/ardour/midi_playlist_source.cc
index 4f474f7119..3d9c5b1e9f 100644
--- a/libs/ardour/midi_playlist_source.cc
+++ b/libs/ardour/midi_playlist_source.cc
@@ -126,7 +126,8 @@ MidiPlaylistSource::read_unlocked (const Lock& lock,
 				   Evoral::EventSink<framepos_t>& dst,
 				   framepos_t /*position*/,
 				   framepos_t start, framecnt_t cnt,
-				   MidiStateTracker*) const
+				   MidiStateTracker*,
+				   MidiChannelFilter*) const
 {
 	boost::shared_ptr<MidiPlaylist> mp = boost::dynamic_pointer_cast<MidiPlaylist> (_playlist);
 
diff --git a/libs/ardour/midi_region.cc b/libs/ardour/midi_region.cc
index 5c197761ac..3e4a656ebe 100644
--- a/libs/ardour/midi_region.cc
+++ b/libs/ardour/midi_region.cc
@@ -230,9 +230,15 @@ MidiRegion::set_position_internal (framepos_t pos, bool allow_bbt_recompute)
 }
 
 framecnt_t
-MidiRegion::read_at (Evoral::EventSink<framepos_t>& out, framepos_t position, framecnt_t dur, uint32_t chan_n, NoteMode mode, MidiStateTracker* tracker) const
+MidiRegion::read_at (Evoral::EventSink<framepos_t>& out,
+                     framepos_t                     position,
+                     framecnt_t                     dur,
+                     uint32_t                       chan_n,
+                     NoteMode                       mode,
+                     MidiStateTracker*              tracker,
+                     MidiChannelFilter*             filter) const
 {
-	return _read_at (_sources, out, position, dur, chan_n, mode, tracker);
+	return _read_at (_sources, out, position, dur, chan_n, mode, tracker, filter);
 }
 
 framecnt_t
@@ -248,7 +254,8 @@ MidiRegion::_read_at (const SourceList&              /*srcs*/,
                       framecnt_t                     dur,
                       uint32_t                       chan_n,
                       NoteMode                       mode,
-                      MidiStateTracker*              tracker) const
+                      MidiStateTracker*              tracker,
+                      MidiChannelFilter*             filter) const
 {
 	frameoffset_t internal_offset = 0;
 	framecnt_t    to_read         = 0;
@@ -301,6 +308,7 @@ MidiRegion::_read_at (const SourceList&              /*srcs*/,
 			_start + internal_offset, // where to start reading in the source
 			to_read, // read duration in frames
 			tracker,
+			filter,
 			_filtered_parameters
 		    ) != to_read) {
 		return 0; /* "read nothing" */
diff --git a/libs/ardour/midi_source.cc b/libs/ardour/midi_source.cc
index 47cfb1b0a0..ab972fabd8 100644
--- a/libs/ardour/midi_source.cc
+++ b/libs/ardour/midi_source.cc
@@ -38,10 +38,11 @@
 #include "evoral/EventSink.hpp"
 
 #include "ardour/debug.h"
+#include "ardour/file_source.h"
+#include "ardour/midi_channel_filter.h"
 #include "ardour/midi_model.h"
-#include "ardour/midi_state_tracker.h"
 #include "ardour/midi_source.h"
-#include "ardour/file_source.h"
+#include "ardour/midi_state_tracker.h"
 #include "ardour/session.h"
 #include "ardour/session_directory.h"
 #include "ardour/source_factory.h"
@@ -190,6 +191,7 @@ MidiSource::midi_read (const Lock&                        lm,
                        framepos_t                         start,
                        framecnt_t                         cnt,
                        MidiStateTracker*                  tracker,
+                       MidiChannelFilter*                 filter,
                        const std::set<Evoral::Parameter>& filtered) const
 {
 	BeatsFramesConverter converter(_session.tempo_map(), source_start);
@@ -218,6 +220,13 @@ MidiSource::midi_read (const Lock&                        lm,
 		for (; i != _model->end(); ++i) {
 			const framecnt_t time_frames = converter.to(i->time());
 			if (time_frames < start + cnt) {
+				if (filter && filter->filter(i->buffer(), i->size())) {
+					DEBUG_TRACE (DEBUG::MidiSourceIO,
+					             string_compose ("%1: filter event @ %2 type %3 size %4\n",
+					                             _name, time_frames + source_start, i->event_type(), i->size()));
+					continue;
+				}
+
 				// Offset by source start to convert event time to session time
 				dst.write (time_frames + source_start, i->event_type(), i->size(), i->buffer());
 
@@ -237,7 +246,7 @@ MidiSource::midi_read (const Lock&                        lm,
 		}
 		return cnt;
 	} else {
-		return read_unlocked (lm, dst, source_start, start, cnt, tracker);
+		return read_unlocked (lm, dst, source_start, start, cnt, tracker, filter);
 	}
 }
 
diff --git a/libs/ardour/midi_track.cc b/libs/ardour/midi_track.cc
index b8f53a87d0..3f15464481 100644
--- a/libs/ardour/midi_track.cc
+++ b/libs/ardour/midi_track.cc
@@ -29,7 +29,6 @@
 #define isnan_local std::isnan
 #endif
 
-#include "pbd/ffs.h"
 #include "pbd/enumwriter.h"
 #include "pbd/convert.h"
 #include "evoral/midi_util.h"
@@ -72,8 +71,6 @@ MidiTrack::MidiTrack (Session& sess, string name, Route::Flag flag, TrackMode mo
 	, _note_mode(Sustained)
 	, _step_editing (false)
 	, _input_active (true)
-	, _playback_channel_mask(0x0000ffff)
-	, _capture_channel_mask(0x0000ffff)
 {
 }
 
@@ -387,7 +384,7 @@ MidiTrack::roll (pframes_t nframes, framepos_t start_frame, framepos_t end_frame
 	fill_buffers_with_input (bufs, _input, nframes);
 
 	/* filter captured data before meter sees it */
-	filter_channels (bufs, get_capture_channel_mode(), get_capture_channel_mask());
+	_capture_filter.filter (bufs);
 
 	if (_meter_point == MeterInput && (_monitoring & MonitorInput || _diskstream->record_enabled())) {
 		_meter->run (bufs, start_frame, end_frame, nframes, true);
@@ -402,9 +399,7 @@ MidiTrack::roll (pframes_t nframes, framepos_t start_frame, framepos_t end_frame
 		return dret;
 	}
 
-	/* filter playback data before we do anything else */
-	
-	filter_channels (bufs, get_playback_channel_mode(), get_playback_channel_mask ());
+	/* note diskstream uses our filter to filter/map playback channels appropriately. */
 
 	if (monitoring_state() == MonitoringInput) {
 
@@ -549,43 +544,6 @@ MidiTrack::push_midi_input_to_step_edit_ringbuffer (framecnt_t nframes)
 	}
 }
 
-void 
-MidiTrack::filter_channels (BufferSet& bufs, ChannelMode mode, uint32_t mask)
-{
-	if (mode == AllChannels) {
-		return;
-	}
-
-	MidiBuffer& buf (bufs.get_midi (0));
-	
-	for (MidiBuffer::iterator e = buf.begin(); e != buf.end(); ) {
-		
-		Evoral::MIDIEvent<framepos_t> ev(*e, false);
-
-		if (ev.is_channel_event()) {
-			switch (mode) {
-			case FilterChannels:
-				if (0 == ((1<<ev.channel()) & mask)) {
-					e = buf.erase (e);
-				} else {
-					++e;
-				}
-				break;
-			case ForceChannel:
-				ev.set_channel (PBD::ffs (mask) - 1);
-				++e;
-				break;
-			case AllChannels:
-				/* handled by the opening if() */
-				++e;
-				break;
-			}
-		} else {
-			++e;
-		}
-	}
-}
-
 void
 MidiTrack::write_out_of_band_data (BufferSet& bufs, framepos_t /*start*/, framepos_t /*end*/, framecnt_t nframes)
 {
@@ -815,52 +773,34 @@ MidiTrack::write_source (uint32_t)
 }
 
 void
-MidiTrack::set_playback_channel_mode(ChannelMode mode, uint16_t mask) 
+MidiTrack::set_playback_channel_mode(ChannelMode mode, uint16_t mask)
 {
-	ChannelMode old = get_playback_channel_mode ();
-	uint16_t old_mask = get_playback_channel_mask ();
-
-	if (old != mode || mask != old_mask) {
-		_set_playback_channel_mode (mode, mask);
-		PlaybackChannelModeChanged ();
-		_session.set_dirty ();
+	if (_playback_filter.set_channel_mode(mode, mask)) {
+		_session.set_dirty();
 	}
 }
 
 void
-MidiTrack::set_capture_channel_mode(ChannelMode mode, uint16_t mask) 
+MidiTrack::set_capture_channel_mode(ChannelMode mode, uint16_t mask)
 {
-	ChannelMode old = get_capture_channel_mode ();
-	uint16_t old_mask = get_capture_channel_mask ();
-
-	if (old != mode || mask != old_mask) {
-		_set_capture_channel_mode (mode, mask);
-		CaptureChannelModeChanged ();
-		_session.set_dirty ();
+	if (_capture_filter.set_channel_mode(mode, mask)) {
+		_session.set_dirty();
 	}
 }
 
 void
 MidiTrack::set_playback_channel_mask (uint16_t mask)
 {
-	uint16_t old = get_playback_channel_mask();
-
-	if (old != mask) {
-		_set_playback_channel_mask (mask);
-		PlaybackChannelMaskChanged ();
-		_session.set_dirty ();
+	if (_playback_filter.set_channel_mask(mask)) {
+		_session.set_dirty();
 	}
 }
 
 void
 MidiTrack::set_capture_channel_mask (uint16_t mask)
 {
-	uint16_t old = get_capture_channel_mask();
-
-	if (old != mask) {
-		_set_capture_channel_mask (mask);
-		CaptureChannelMaskChanged ();
-		_session.set_dirty ();
+	if (_capture_filter.set_channel_mask(mask)) {
+		_session.set_dirty();
 	}
 }
 
@@ -949,7 +889,7 @@ MidiTrack::act_on_mute ()
 	if (muted() || _mute_master->muted_by_others_at(MuteMaster::AllPoints)) {
 		/* only send messages for channels we are using */
 
-		uint16_t mask = get_playback_channel_mask();
+		uint16_t mask = _playback_filter.get_channel_mask();
 
 		for (uint8_t channel = 0; channel <= 0xF; channel++) {
 
diff --git a/libs/ardour/smf_source.cc b/libs/ardour/smf_source.cc
index 7f5e8059c9..d5c89b5ee9 100644
--- a/libs/ardour/smf_source.cc
+++ b/libs/ardour/smf_source.cc
@@ -37,13 +37,14 @@
 #include "evoral/Control.hpp"
 #include "evoral/SMF.hpp"
 
+#include "ardour/debug.h"
+#include "ardour/midi_channel_filter.h"
 #include "ardour/midi_model.h"
 #include "ardour/midi_ring_buffer.h"
 #include "ardour/midi_state_tracker.h"
 #include "ardour/parameter_types.h"
 #include "ardour/session.h"
 #include "ardour/smf_source.h"
-#include "ardour/debug.h"
 
 #include "i18n.h"
 
@@ -208,7 +209,8 @@ SMFSource::read_unlocked (const Lock&                    lock,
                           framepos_t const               source_start,
                           framepos_t                     start,
                           framecnt_t                     duration,
-                          MidiStateTracker*              tracker) const
+                          MidiStateTracker*              tracker,
+                          MidiChannelFilter*             filter) const
 {
 	int      ret  = 0;
 	uint64_t time = 0; // in SMF ticks, 1 tick per _ppqn
@@ -281,9 +283,11 @@ SMFSource::read_unlocked (const Lock&                    lock,
 		const framepos_t ev_frame_time = converter.to(Evoral::Beats::ticks_at_rate(time, ppqn())) + source_start;
 
 		if (ev_frame_time < start + duration) {
-			destination.write (ev_frame_time, ev_type, ev_size, ev_buffer);
-			if (tracker) {
-				tracker->track(ev_buffer);
+			if (!filter || !filter->filter(ev_buffer, ev_size)) {
+				destination.write (ev_frame_time, ev_type, ev_size, ev_buffer);
+				if (tracker) {
+					tracker->track(ev_buffer);
+				}
 			}
 		} else {
 			break;
diff --git a/libs/ardour/wscript b/libs/ardour/wscript
index 82aa2085f8..41d0edc3dd 100644
--- a/libs/ardour/wscript
+++ b/libs/ardour/wscript
@@ -109,6 +109,7 @@ libardour_sources = [
         'meter.cc',
         'midi_automation_list_binder.cc',
         'midi_buffer.cc',
+        'midi_channel_filter.cc',
         'midi_clock_slave.cc',
         'midi_diskstream.cc',
         'midi_model.cc',