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.

1 files changed, 97 insertions, 0 deletions

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__ */