Replace May/Done/NotDone signal sets with one signal and extend

this treatment to anything that caused Player::setup_pieces.  This should
fix out-of-sequence Player emissions caused by setup_pieces being called
by one thread while the butler is calling pass().

12 files changed, 135 insertions, 213 deletions

diff --git a/src/lib/butler.cc b/src/lib/butler.cc
index f04b324cd..3a75e67d7 100644
--- a/src/lib/butler.cc
+++ b/src/lib/butler.cc
@@ -65,9 +65,7 @@ Butler::Butler (shared_ptr<Player> player, shared_ptr<Log> log, AudioMapping aud
 	_player_video_connection = _player->Video.connect (bind (&Butler::video, this, _1, _2));
 	_player_audio_connection = _player->Audio.connect (bind (&Butler::audio, this, _1, _2));
 	_player_text_connection = _player->Text.connect (bind (&Butler::text, this, _1, _2, _3));
-	_player_may_change_connection = _player->MayChange.connect (bind (&Butler::suspend, this));
-	_player_changed_connection = _player->Changed.connect (bind (&Butler::return_seek, this, _2));
-	_player_not_changed_connection = _player->NotChanged.connect (bind (&Butler::return_seek, this, false));
+	_player_change_connection = _player->Change.connect (bind (&Butler::player_change, this, _1, _3));
 	_thread = new boost::thread (bind (&Butler::thread, this));
 #ifdef DCPOMATIC_LINUX
 	pthread_setname_np (_thread->native_handle(), "butler");
@@ -107,10 +105,6 @@ Butler::~Butler ()
 bool
 Butler::should_run () const
 {
-	if (_suspended) {
-		return false;
-	}
-
 	if (_video.size() >= MAXIMUM_VIDEO_READAHEAD * 10) {
 		/* This is way too big */
 		throw ProgrammingError
@@ -131,7 +125,7 @@ Butler::should_run () const
 		LOG_WARNING ("Butler audio buffers reached %1 frames (video is %2)", _audio.size(), _video.size());
 	}
 
-	if (_stop_thread || _finished || _died) {
+	if (_stop_thread || _finished || _died || _suspended) {
 		/* Definitely do not run */
 		return false;
 	}
@@ -198,7 +192,7 @@ Butler::get_video ()
 	boost::mutex::scoped_lock lm (_mutex);
 
 	/* Wait for data if we have none */
-	while (_video.empty() && !_finished && !_died) {
+	while (_video.empty() && !_finished && !_died && !_suspended) {
 		_arrived.wait (lm);
 	}
 
@@ -316,27 +310,33 @@ Butler::memory_used () const
 }
 
 void
-Butler::return_seek (bool frequent)
+Butler::player_change (ChangeType type, bool frequent)
 {
 	boost::mutex::scoped_lock lm (_mutex);
-	if (_died || _pending_seek_position || frequent) {
-		return;
-	}
 
-	DCPTime seek_to;
-	DCPTime next = _video.get().second;
-	if (_awaiting && _awaiting > next) {
-		/* We have recently done a player_changed seek and our buffers haven't been refilled yet,
-		   so assume that we're seeking to the same place as last time.
-		*/
-		seek_to = *_awaiting;
-	} else {
-		seek_to = next;
-	}
+	if (type == CHANGE_TYPE_PENDING) {
+		_suspended = true;
+	} else if (type == CHANGE_TYPE_DONE) {
+
+		if (_died || _pending_seek_position || frequent) {
+			return;
+		}
+
+		DCPTime seek_to;
+		DCPTime next = _video.get().second;
+		if (_awaiting && _awaiting > next) {
+			/* We have recently done a player_changed seek and our buffers haven't been refilled yet,
+			   so assume that we're seeking to the same place as last time.
+			*/
+			seek_to = *_awaiting;
+		} else {
+			seek_to = next;
+		}
 
-	seek_unlocked (seek_to, true);
-	_suspended = false;
-	_awaiting = seek_to;
+		seek_unlocked (seek_to, true);
+		_suspended = false;
+		_awaiting = seek_to;
+	}
 }
 
 void
@@ -349,10 +349,3 @@ Butler::text (PlayerText pt, TextType type, DCPTimePeriod period)
 	boost::mutex::scoped_lock lm2 (_buffers_mutex);
 	_closed_caption.put (make_pair(pt, period));
 }
-
-void
-Butler::suspend ()
-{
-	boost::mutex::scoped_lock lm (_mutex);
-	_suspended = true;
-}
diff --git a/src/lib/butler.h b/src/lib/butler.h
index 6a13ed2d7..513176821 100644
--- a/src/lib/butler.h
+++ b/src/lib/butler.h
@@ -56,8 +56,7 @@ private:
 	void text (PlayerText pt, TextType type, DCPTimePeriod period);
 	bool should_run () const;
 	void prepare (boost::weak_ptr<PlayerVideo> video) const;
-	void suspend ();
-	void return_seek (bool frequent);
+	void player_change (ChangeType type, bool frequent);
 	void seek_unlocked (DCPTime position, bool accurate);
 
 	boost::shared_ptr<Player> _player;
@@ -102,7 +101,5 @@ private:
 	boost::signals2::scoped_connection _player_video_connection;
 	boost::signals2::scoped_connection _player_audio_connection;
 	boost::signals2::scoped_connection _player_text_connection;
-	boost::signals2::scoped_connection _player_may_change_connection;
-	boost::signals2::scoped_connection _player_changed_connection;
-	boost::signals2::scoped_connection _player_not_changed_connection;
+	boost::signals2::scoped_connection _player_change_connection;
 };
diff --git a/src/lib/content.cc b/src/lib/content.cc
index 8fd36a1d8..ae0b08dcc 100644
--- a/src/lib/content.cc
+++ b/src/lib/content.cc
@@ -179,10 +179,14 @@ Content::examine (shared_ptr<Job> job)
 }
 
 void
-Content::signal_changed (int p)
+Content::signal_change (ChangeType c, int p)
 {
 	try {
-		emit (boost::bind (boost::ref(Changed), shared_from_this(), p, _change_signals_frequent));
+		if (c == CHANGE_TYPE_PENDING || c == CHANGE_TYPE_CANCELLED) {
+			Change (c, shared_from_this(), p, _change_signals_frequent);
+		} else {
+			emit (boost::bind (boost::ref(Change), c, shared_from_this(), p, _change_signals_frequent));
+		}
 	} catch (boost::bad_weak_ptr) {
 		/* This must be during construction; never mind */
 	}
diff --git a/src/lib/content.h b/src/lib/content.h
index c9edf6e22..e8710ccb7 100644
--- a/src/lib/content.h
+++ b/src/lib/content.h
@@ -178,14 +178,8 @@ public:
 
 	std::list<UserProperty> user_properties () const;
 
-	/* May be emitted from any thread */
-	boost::signals2::signal<void ()> MayChange;
-
-	/* Emitted from the GUI thread */
-	boost::signals2::signal<void (boost::weak_ptr<Content>, int, bool)> Changed;
-
-	/* May be emitted from any thread */
-	boost::signals2::signal<void ()> NotChanged;
+	/* CHANGE_PENDING and CHANGE_CANCELLED may be emitted from any thread; CHANGE_DONE always from GUI thread */
+	boost::signals2::signal<void (ChangeType, boost::weak_ptr<Content>, int, bool)> Change;
 
 	boost::shared_ptr<VideoContent> video;
 	boost::shared_ptr<AudioContent> audio;
@@ -215,7 +209,7 @@ private:
 	friend struct audio_sampling_rate_test;
 	friend class ContentChange;
 
-	void signal_changed (int);
+	void signal_change (ChangeType, int);
 
 	std::string _digest;
 	DCPTime _position;
diff --git a/src/lib/content_change.cc b/src/lib/content_change.cc
index c286f80eb..6e390dc76 100644
--- a/src/lib/content_change.cc
+++ b/src/lib/content_change.cc
@@ -26,16 +26,16 @@ ContentChange::ContentChange (Content* c, int p)
 	, _property (p)
 	, _done (true)
 {
-	_content->MayChange ();
+	_content->signal_change (CHANGE_TYPE_PENDING, _property);
 }
 
 
 ContentChange::~ContentChange ()
 {
 	if (_done) {
-		_content->signal_changed (_property);
+		_content->signal_change (CHANGE_TYPE_DONE, _property);
 	} else {
-		_content->NotChanged ();
+		_content->signal_change (CHANGE_TYPE_CANCELLED, _property);
 	}
 }
 
diff --git a/src/lib/film.cc b/src/lib/film.cc
index ba97f833e..846e8ac51 100644
--- a/src/lib/film.cc
+++ b/src/lib/film.cc
@@ -160,9 +160,9 @@ Film::Film (optional<boost::filesystem::path> dir)
 {
 	set_isdcf_date_today ();
 
-	_playlist_changed_connection = _playlist->Changed.connect (bind (&Film::playlist_changed, this));
+	_playlist_change_connection = _playlist->Change.connect (bind (&Film::playlist_change, this, _1));
 	_playlist_order_changed_connection = _playlist->OrderChanged.connect (bind (&Film::playlist_order_changed, this));
-	_playlist_content_changed_connection = _playlist->ContentChanged.connect (bind (&Film::playlist_content_changed, this, _1, _2, _3));
+	_playlist_content_change_connection = _playlist->ContentChange.connect (bind (&Film::playlist_content_change, this, _1, _2, _3, _4));
 
 	if (dir) {
 		/* Make state.directory a complete path without ..s (where possible)
@@ -1154,8 +1154,12 @@ Film::active_frame_rate_change (DCPTime t) const
 }
 
 void
-Film::playlist_content_changed (weak_ptr<Content> c, int p, bool frequent)
+Film::playlist_content_change (ChangeType type, weak_ptr<Content> c, int p, bool frequent)
 {
+	if (type != CHANGE_TYPE_DONE) {
+		return;
+	}
+
 	_dirty = true;
 
 	if (p == ContentProperty::VIDEO_FRAME_RATE) {
@@ -1164,14 +1168,16 @@ Film::playlist_content_changed (weak_ptr<Content> c, int p, bool frequent)
 		signal_changed (NAME);
 	}
 
-	emit (boost::bind (boost::ref (ContentChanged), c, p, frequent));
+	emit (boost::bind (boost::ref (ContentChange), type, c, p, frequent));
 }
 
 void
-Film::playlist_changed ()
+Film::playlist_change (ChangeType type)
 {
-	signal_changed (CONTENT);
-	signal_changed (NAME);
+	if (type == CHANGE_TYPE_DONE) {
+		signal_changed (CONTENT);
+		signal_changed (NAME);
+	}
 }
 
 void
diff --git a/src/lib/film.h b/src/lib/film.h
index 20a1e2ca6..c6c8403cb 100644
--- a/src/lib/film.h
+++ b/src/lib/film.h
@@ -327,7 +327,7 @@ public:
 	mutable boost::signals2::signal<void (Property)> Changed;
 
 	/** Emitted when some property of our content has changed */
-	mutable boost::signals2::signal<void (boost::weak_ptr<Content>, int, bool)> ContentChanged;
+	mutable boost::signals2::signal<void (ChangeType, boost::weak_ptr<Content>, int, bool)> ContentChange;
 
 	/** Current version number of the state file */
 	static int const current_state_version;
@@ -338,9 +338,9 @@ private:
 
 	void signal_changed (Property);
 	std::string video_identifier () const;
-	void playlist_changed ();
+	void playlist_change (ChangeType);
 	void playlist_order_changed ();
-	void playlist_content_changed (boost::weak_ptr<Content>, int, bool frequent);
+	void playlist_content_change (ChangeType type, boost::weak_ptr<Content>, int, bool frequent);
 	void maybe_add_content (boost::weak_ptr<Job>, boost::weak_ptr<Content>, bool disable_audio_analysis);
 	void audio_analysis_finished ();
 
@@ -401,9 +401,9 @@ private:
 	/** film being used as a template, or 0 */
 	boost::shared_ptr<Film> _template_film;
 
-	boost::signals2::scoped_connection _playlist_changed_connection;
+	boost::signals2::scoped_connection _playlist_change_connection;
 	boost::signals2::scoped_connection _playlist_order_changed_connection;
-	boost::signals2::scoped_connection _playlist_content_changed_connection;
+	boost::signals2::scoped_connection _playlist_content_change_connection;
 	std::list<boost::signals2::connection> _job_connections;
 	std::list<boost::signals2::connection> _audio_analysis_connections;
 
diff --git a/src/lib/player.cc b/src/lib/player.cc
index df8c47cf9..0c3aea028 100644
--- a/src/lib/player.cc
+++ b/src/lib/player.cc
@@ -98,10 +98,8 @@ Player::Player (shared_ptr<const Film> film, shared_ptr<const Playlist> playlist
 	, _shuffler (0)
 {
 	_film_changed_connection = _film->Changed.connect (bind (&Player::film_changed, this, _1));
-	_playlist_changed_connection = _playlist->Changed.connect (bind (&Player::playlist_changed, this));
-	_playlist_content_may_change_connection = _playlist->ContentMayChange.connect (bind(&Player::playlist_content_may_change, this));
-	_playlist_content_changed_connection = _playlist->ContentChanged.connect (bind(&Player::playlist_content_changed, this, _1, _2, _3));
-	_playlist_content_not_changed_connection = _playlist->ContentNotChanged.connect (bind(&Player::playlist_content_not_changed, this));
+	_playlist_change_connection = _playlist->Change.connect (bind (&Player::playlist_change, this, _1));
+	_playlist_content_change_connection = _playlist->ContentChange.connect (bind(&Player::playlist_content_change, this, _1, _3, _4));
 	set_video_container_size (_film->frame_size ());
 
 	film_changed (Film::AUDIO_PROCESSOR);
@@ -224,78 +222,21 @@ Player::setup_pieces_unlocked ()
 }
 
 void
-Player::playlist_content_may_change ()
+Player::playlist_content_change (ChangeType type, int property, bool frequent)
 {
-	{
+	if (type == CHANGE_TYPE_PENDING) {
 		boost::mutex::scoped_lock lm (_mutex);
 		/* The player content is probably about to change, so we can't carry on
 		   until that has happened and we've rebuilt our pieces.  Stop pass()
 		   and seek() from working until then.
 		*/
 		_suspended = true;
+	} else if (type == CHANGE_TYPE_DONE) {
+		/* A change in our content has gone through.  Re-build our pieces. */
+		setup_pieces ();
 	}
 
-	MayChange ();
-}
-
-void
-Player::playlist_content_changed (weak_ptr<Content> w, int property, bool frequent)
-{
-	/* A change in our content has gone through.  Re-build our pieces and signal
-	   it to anybody that is interested.
-	*/
-
-	shared_ptr<Content> c = w.lock ();
-	if (!c) {
-		return;
-	}
-
-	setup_pieces ();
-
-	if (
-		property == ContentProperty::POSITION ||
-		property == ContentProperty::LENGTH ||
-		property == ContentProperty::TRIM_START ||
-		property == ContentProperty::TRIM_END ||
-		property == ContentProperty::PATH ||
-		property == VideoContentProperty::FRAME_TYPE ||
-		property == VideoContentProperty::COLOUR_CONVERSION ||
-		property == AudioContentProperty::STREAMS ||
-		property == DCPContentProperty::NEEDS_ASSETS ||
-		property == DCPContentProperty::NEEDS_KDM ||
-		property == DCPContentProperty::CPL ||
-		property == TextContentProperty::COLOUR ||
-		property == TextContentProperty::EFFECT ||
-		property == TextContentProperty::EFFECT_COLOUR ||
-		property == FFmpegContentProperty::SUBTITLE_STREAM ||
-		property == FFmpegContentProperty::FILTERS ||
-		property == TextContentProperty::LINE_SPACING ||
-		property == TextContentProperty::OUTLINE_WIDTH ||
-		property == TextContentProperty::Y_SCALE ||
-		property == TextContentProperty::FADE_IN ||
-		property == TextContentProperty::FADE_OUT ||
-		property == ContentProperty::VIDEO_FRAME_RATE ||
-		property == TextContentProperty::USE ||
-		property == TextContentProperty::X_OFFSET ||
-		property == TextContentProperty::Y_OFFSET ||
-		property == TextContentProperty::X_SCALE ||
-		property == TextContentProperty::FONTS ||
-		property == TextContentProperty::TYPE ||
-		property == VideoContentProperty::CROP ||
-		property == VideoContentProperty::SCALE ||
-		property == VideoContentProperty::FADE_IN ||
-		property == VideoContentProperty::FADE_OUT
-		) {
-
-		Changed (property, frequent);
-	}
-}
-
-void
-Player::playlist_content_not_changed ()
-{
-	/* A possible content change did end up happening for some reason */
-	NotChanged ();
+	Change (type, property, frequent);
 }
 
 void
@@ -314,14 +255,16 @@ Player::set_video_container_size (dcp::Size s)
 		_black_image->make_black ();
 	}
 
-	Changed (PlayerProperty::VIDEO_CONTAINER_SIZE, false);
+	Change (CHANGE_TYPE_DONE, PlayerProperty::VIDEO_CONTAINER_SIZE, false);
 }
 
 void
-Player::playlist_changed ()
+Player::playlist_change (ChangeType type)
 {
-	setup_pieces ();
-	Changed (PlayerProperty::PLAYLIST, false);
+	if (type == CHANGE_TYPE_DONE) {
+		setup_pieces ();
+	}
+	Change (type, PlayerProperty::PLAYLIST, false);
 }
 
 void
@@ -333,13 +276,14 @@ Player::film_changed (Film::Property p)
 	*/
 
 	if (p == Film::CONTAINER) {
-		Changed (PlayerProperty::FILM_CONTAINER, false);
+		Change (CHANGE_TYPE_PENDING, PlayerProperty::FILM_CONTAINER, false);
 	} else if (p == Film::VIDEO_FRAME_RATE) {
 		/* Pieces contain a FrameRateChange which contains the DCP frame rate,
 		   so we need new pieces here.
 		*/
+		/* XXX: missing PENDING! */
 		setup_pieces ();
-		Changed (PlayerProperty::FILM_VIDEO_FRAME_RATE, false);
+		Change (CHANGE_TYPE_DONE, PlayerProperty::FILM_VIDEO_FRAME_RATE, false);
 	} else if (p == Film::AUDIO_PROCESSOR) {
 		if (_film->audio_processor ()) {
 			boost::mutex::scoped_lock lm (_mutex);
@@ -1187,10 +1131,14 @@ Player::discard_audio (shared_ptr<const AudioBuffers> audio, DCPTime time, DCPTi
 void
 Player::set_dcp_decode_reduction (optional<int> reduction)
 {
+	Change (CHANGE_TYPE_PENDING, PlayerProperty::DCP_DECODE_REDUCTION, false);
+
 	{
 		boost::mutex::scoped_lock lm (_mutex);
 
 		if (reduction == _dcp_decode_reduction) {
+			lm.unlock ();
+			Change (CHANGE_TYPE_CANCELLED, PlayerProperty::DCP_DECODE_REDUCTION, false);
 			return;
 		}
 
@@ -1198,7 +1146,7 @@ Player::set_dcp_decode_reduction (optional<int> reduction)
 		setup_pieces_unlocked ();
 	}
 
-	Changed (PlayerProperty::DCP_DECODE_REDUCTION, false);
+	Change (CHANGE_TYPE_DONE, PlayerProperty::DCP_DECODE_REDUCTION, false);
 }
 
 optional<DCPTime>
diff --git a/src/lib/player.h b/src/lib/player.h
index f7ab1000d..165820799 100644
--- a/src/lib/player.h
+++ b/src/lib/player.h
@@ -88,19 +88,7 @@ public:
 
 	boost::optional<DCPTime> content_time_to_dcp (boost::shared_ptr<Content> content, ContentTime t);
 
-	/* The player's internal state may be about to change such so
-	   that its emissions from Video and Audio will suddenly be
-	   from an undefined position.  Listeners should prepare
-	   themselves for this possibility.
-	*/
-	boost::signals2::signal<void ()> MayChange;
-
-	/** The player's internal state has now changed.
-	 *
-	 *  The first parameter is what changed.
-	 *  The second parameter is true if these signals are currently likely to be frequent.
-	 */
-	boost::signals2::signal<void (int, bool)> Changed;
+	boost::signals2::signal<void (ChangeType, int, bool)> Change;
 
 	/** The change suggested by a MayChange did not happen */
 	boost::signals2::signal<void ()> NotChanged;
@@ -125,10 +113,8 @@ private:
 	void setup_pieces_unlocked ();
 	void flush ();
 	void film_changed (Film::Property);
-	void playlist_changed ();
-	void playlist_content_may_change ();
-	void playlist_content_changed (boost::weak_ptr<Content>, int, bool);
-	void playlist_content_not_changed ();
+	void playlist_change (ChangeType);
+	void playlist_content_change (ChangeType, int, bool);
 	std::list<PositionImage> transform_bitmap_texts (std::list<BitmapText>) const;
 	Frame dcp_to_content_video (boost::shared_ptr<const Piece> piece, DCPTime t) const;
 	DCPTime content_video_to_dcp (boost::shared_ptr<const Piece> piece, Frame f) const;
@@ -217,10 +203,8 @@ private:
 	boost::shared_ptr<AudioProcessor> _audio_processor;
 
 	boost::signals2::scoped_connection _film_changed_connection;
-	boost::signals2::scoped_connection _playlist_changed_connection;
-	boost::signals2::scoped_connection _playlist_content_may_change_connection;
-	boost::signals2::scoped_connection _playlist_content_changed_connection;
-	boost::signals2::scoped_connection _playlist_content_not_changed_connection;
+	boost::signals2::scoped_connection _playlist_change_connection;
+	boost::signals2::scoped_connection _playlist_content_change_connection;
 };
 
 #endif
diff --git a/src/lib/playlist.cc b/src/lib/playlist.cc
index 1bb0ad0d6..e4fc0f072 100644
--- a/src/lib/playlist.cc
+++ b/src/lib/playlist.cc
@@ -65,48 +65,38 @@ Playlist::~Playlist ()
 }
 
 void
-Playlist::content_may_change ()
+Playlist::content_change (ChangeType type, weak_ptr<Content> content, int property, bool frequent)
 {
-	ContentMayChange ();
-}
+	if (type == CHANGE_TYPE_DONE) {
+		if (
+			property == ContentProperty::TRIM_START ||
+			property == ContentProperty::TRIM_END ||
+			property == ContentProperty::LENGTH ||
+			property == VideoContentProperty::FRAME_TYPE
+			) {
+			/* Don't respond to position changes here, as:
+			   - sequencing after earlier/later changes is handled by move_earlier/move_later
+			   - any other position changes will be timeline drags which should not result in content
+			   being sequenced.
+			*/
+			maybe_sequence ();
+		}
 
-void
-Playlist::content_not_changed ()
-{
-	ContentNotChanged ();
-}
+		if (
+			property == ContentProperty::POSITION ||
+			property == ContentProperty::LENGTH ||
+			property == ContentProperty::TRIM_START ||
+			property == ContentProperty::TRIM_END) {
 
-void
-Playlist::content_changed (weak_ptr<Content> content, int property, bool frequent)
-{
-	if (
-		property == ContentProperty::TRIM_START ||
-		property == ContentProperty::TRIM_END ||
-		property == ContentProperty::LENGTH ||
-		property == VideoContentProperty::FRAME_TYPE
-		) {
-		/* Don't respond to position changes here, as:
-		   - sequencing after earlier/later changes is handled by move_earlier/move_later
-		   - any other position changes will be timeline drags which should not result in content
-		   being sequenced.
-		*/
-		maybe_sequence ();
-	}
-
-	if (
-		property == ContentProperty::POSITION ||
-		property == ContentProperty::LENGTH ||
-		property == ContentProperty::TRIM_START ||
-		property == ContentProperty::TRIM_END) {
-
-		ContentList old = _content;
-		sort (_content.begin(), _content.end(), ContentSorter ());
-		if (_content != old) {
-			OrderChanged ();
+			ContentList old = _content;
+			sort (_content.begin(), _content.end(), ContentSorter ());
+			if (_content != old) {
+				OrderChanged ();
+			}
 		}
 	}
 
-	ContentChanged (content, property, frequent);
+	ContentChange (type, content, property, frequent);
 }
 
 void
@@ -215,15 +205,18 @@ Playlist::as_xml (xmlpp::Node* node, bool with_content_paths)
 void
 Playlist::add (shared_ptr<Content> c)
 {
+	Change (CHANGE_TYPE_PENDING);
 	_content.push_back (c);
 	sort (_content.begin(), _content.end(), ContentSorter ());
 	reconnect ();
-	Changed ();
+	Change (CHANGE_TYPE_DONE);
 }
 
 void
 Playlist::remove (shared_ptr<Content> c)
 {
+	Change (CHANGE_TYPE_PENDING);
+
 	ContentList::iterator i = _content.begin ();
 	while (i != _content.end() && *i != c) {
 		++i;
@@ -231,7 +224,9 @@ Playlist::remove (shared_ptr<Content> c)
 
 	if (i != _content.end ()) {
 		_content.erase (i);
-		Changed ();
+		Change (CHANGE_TYPE_DONE);
+	} else {
+		Change (CHANGE_TYPE_CANCELLED);
 	}
 
 	/* This won't change order, so it does not need a sort */
@@ -240,6 +235,8 @@ Playlist::remove (shared_ptr<Content> c)
 void
 Playlist::remove (ContentList c)
 {
+	Change (CHANGE_TYPE_PENDING);
+
 	BOOST_FOREACH (shared_ptr<Content> i, c) {
 		ContentList::iterator j = _content.begin ();
 		while (j != _content.end() && *j != i) {
@@ -253,7 +250,7 @@ Playlist::remove (ContentList c)
 
 	/* This won't change order, so it does not need a sort */
 
-	Changed ();
+	Change (CHANGE_TYPE_DONE);
 }
 
 class FrameRateCandidate
@@ -362,9 +359,7 @@ Playlist::reconnect ()
 	_content_connections.clear ();
 
 	BOOST_FOREACH (shared_ptr<Content> i, _content) {
-		_content_connections.push_back (i->MayChange.connect(boost::bind(&Playlist::content_may_change, this)));
-		_content_connections.push_back (i->Changed.connect(boost::bind(&Playlist::content_changed, this, _1, _2, _3)));
-		_content_connections.push_back (i->NotChanged.connect(boost::bind(&Playlist::content_not_changed, this)));
+		_content_connections.push_back (i->Change.connect(boost::bind(&Playlist::content_change, this, _1, _2, _3, _4)));
 	}
 }
 
@@ -461,6 +456,8 @@ Playlist::repeat (ContentList c, int n)
 		range.second = max (range.second, i->end ());
 	}
 
+	Change (CHANGE_TYPE_PENDING);
+
 	DCPTime pos = range.second;
 	for (int i = 0; i < n; ++i) {
 		BOOST_FOREACH (shared_ptr<Content> j, c) {
@@ -474,7 +471,7 @@ Playlist::repeat (ContentList c, int n)
 	sort (_content.begin(), _content.end(), ContentSorter ());
 
 	reconnect ();
-	Changed ();
+	Change (CHANGE_TYPE_DONE);
 }
 
 void
diff --git a/src/lib/playlist.h b/src/lib/playlist.h
index 649887f72..d55232dad 100644
--- a/src/lib/playlist.h
+++ b/src/lib/playlist.h
@@ -75,21 +75,13 @@ public:
 	void repeat (ContentList, int);
 
 	/** Emitted when content has been added to or removed from the playlist; implies OrderChanged */
-	mutable boost::signals2::signal<void ()> Changed;
+	mutable boost::signals2::signal<void (ChangeType)> Change;
 	mutable boost::signals2::signal<void ()> OrderChanged;
 
-	mutable boost::signals2::signal<void ()> ContentMayChange;
-	/** Emitted when something about a piece of our content has changed;
-	 *  these emissions include when the position of the content changes.
-	 *  Third parameter is true if signals are currently being emitted frequently.
-	 */
-	mutable boost::signals2::signal<void (boost::weak_ptr<Content>, int, bool)> ContentChanged;
-	mutable boost::signals2::signal<void ()> ContentNotChanged;
+	mutable boost::signals2::signal<void (ChangeType, boost::weak_ptr<Content>, int, bool)> ContentChange;
 
 private:
-	void content_may_change ();
-	void content_changed (boost::weak_ptr<Content>, int, bool);
-	void content_not_changed ();
+	void content_change (ChangeType, boost::weak_ptr<Content>, int, bool);
 	void reconnect ();
 
 	/** List of content.  Kept sorted in position order. */
diff --git a/src/lib/types.h b/src/lib/types.h
index 42e2e3eec..22d652b3f 100644
--- a/src/lib/types.h
+++ b/src/lib/types.h
@@ -129,6 +129,13 @@ enum ReelType
 	REELTYPE_BY_LENGTH
 };
 
+enum ChangeType
+{
+	CHANGE_TYPE_PENDING,
+	CHANGE_TYPE_DONE,
+	CHANGE_TYPE_CANCELLED
+};
+
 /** Type of captions.
  *
  *  The generally accepted definitions seem to be: