Some const correctness.

22 files changed, 115 insertions, 71 deletions

diff --git a/src/lib/analyse_audio_job.cc b/src/lib/analyse_audio_job.cc
index 43eecbcbd..88cd65fee 100644
--- a/src/lib/analyse_audio_job.cc
+++ b/src/lib/analyse_audio_job.cc
@@ -84,7 +84,7 @@ AnalyseAudioJob::run ()
 }
 
 void
-AnalyseAudioJob::audio (shared_ptr<AudioBuffers> b)
+AnalyseAudioJob::audio (shared_ptr<const AudioBuffers> b)
 {
 	for (int i = 0; i < b->frames(); ++i) {
 		for (int j = 0; j < b->channels(); ++j) {
diff --git a/src/lib/analyse_audio_job.h b/src/lib/analyse_audio_job.h
index dc1e073ee..5435e0a7c 100644
--- a/src/lib/analyse_audio_job.h
+++ b/src/lib/analyse_audio_job.h
@@ -31,7 +31,7 @@ public:
 	void run ();
 
 private:
-	void audio (boost::shared_ptr<AudioBuffers>);
+	void audio (boost::shared_ptr<const AudioBuffers>);
 
 	int64_t _done;
 	int64_t _samples_per_point;
diff --git a/src/lib/audio_sink.h b/src/lib/audio_sink.h
index f34b24f88..69b3a4b75 100644
--- a/src/lib/audio_sink.h
+++ b/src/lib/audio_sink.h
@@ -24,14 +24,14 @@ class AudioSink
 {
 public:
 	/** Call with some audio data */
-	virtual void process_audio (boost::shared_ptr<AudioBuffers>) = 0;
+	virtual void process_audio (boost::shared_ptr<const AudioBuffers>) = 0;
 };
 
 class TimedAudioSink
 {
 public:
         /** Call with some audio data */
-        virtual void process_audio (boost::shared_ptr<AudioBuffers>, double t) = 0;
+        virtual void process_audio (boost::shared_ptr<const AudioBuffers>, double t) = 0;
 };
 
 #endif
diff --git a/src/lib/audio_source.h b/src/lib/audio_source.h
index e255d566d..c13f1636b 100644
--- a/src/lib/audio_source.h
+++ b/src/lib/audio_source.h
@@ -35,7 +35,7 @@ class AudioSource
 {
 public:
 	/** Emitted when some audio data is ready */
-	boost::signals2::signal<void (boost::shared_ptr<AudioBuffers>)> Audio;
+	boost::signals2::signal<void (boost::shared_ptr<const AudioBuffers>)> Audio;
 
 	void connect_audio (boost::shared_ptr<AudioSink>);
 };
@@ -46,7 +46,7 @@ class TimedAudioSource
 {
 public:
 	/** Emitted when some audio data is ready */
-	boost::signals2::signal<void (boost::shared_ptr<AudioBuffers>, double)> Audio;
+	boost::signals2::signal<void (boost::shared_ptr<const AudioBuffers>, double)> Audio;
 
 	void connect_audio (boost::shared_ptr<AudioSink>);
 	void connect_audio (boost::shared_ptr<TimedAudioSink>);
diff --git a/src/lib/combiner.cc b/src/lib/combiner.cc
index 0a9eaf6b6..250528aeb 100644
--- a/src/lib/combiner.cc
+++ b/src/lib/combiner.cc
@@ -33,9 +33,9 @@ Combiner::Combiner (shared_ptr<Log> log)
  *  @param image Frame image.
  */
 void
-Combiner::process_video (shared_ptr<Image> image, bool, shared_ptr<Subtitle>, double)
+Combiner::process_video (shared_ptr<const Image> image, bool, shared_ptr<Subtitle>, double)
 {
-	_image = image;
+	_image = image->clone ();
 }
 
 /** Process video for the right half of the frame.
@@ -43,7 +43,7 @@ Combiner::process_video (shared_ptr<Image> image, bool, shared_ptr<Subtitle>, do
  *  @param sub Subtitle (which will be put onto the whole frame)
  */
 void
-Combiner::process_video_b (shared_ptr<Image> image, bool, shared_ptr<Subtitle> sub, double t)
+Combiner::process_video_b (shared_ptr<const Image> image, bool, shared_ptr<Subtitle> sub, double t)
 {
 	/* Copy the right half of this image into our _image */
 	/* XXX: this should probably be in the Image class */
diff --git a/src/lib/combiner.h b/src/lib/combiner.h
index a8f1fa804..7ed316e26 100644
--- a/src/lib/combiner.h
+++ b/src/lib/combiner.h
@@ -33,8 +33,8 @@ class Combiner : public TimedVideoProcessor
 public:
 	Combiner (boost::shared_ptr<Log> log);
 
-	void process_video (boost::shared_ptr<Image> i, bool, boost::shared_ptr<Subtitle> s, double);
-	void process_video_b (boost::shared_ptr<Image> i, bool, boost::shared_ptr<Subtitle> s, double);
+	void process_video (boost::shared_ptr<const Image> i, bool, boost::shared_ptr<Subtitle> s, double);
+	void process_video_b (boost::shared_ptr<const Image> i, bool, boost::shared_ptr<Subtitle> s, double);
 
 private:
 	/** The image that we are currently working on */
diff --git a/src/lib/delay_line.cc b/src/lib/delay_line.cc
index 9e6baeba8..b0180800a 100644
--- a/src/lib/delay_line.cc
+++ b/src/lib/delay_line.cc
@@ -37,7 +37,7 @@ DelayLine::DelayLine (shared_ptr<Log> log, double seconds)
 }
 
 void
-DelayLine::process_audio (shared_ptr<AudioBuffers> data, double t)
+DelayLine::process_audio (shared_ptr<const AudioBuffers> data, double t)
 {
 	if (_seconds > 0) {
 		t += _seconds;
@@ -47,7 +47,7 @@ DelayLine::process_audio (shared_ptr<AudioBuffers> data, double t)
 }
 
 void
-DelayLine::process_video (boost::shared_ptr<Image> image, bool same, boost::shared_ptr<Subtitle> sub, double t)
+DelayLine::process_video (shared_ptr<const Image> image, bool same, boost::shared_ptr<Subtitle> sub, double t)
 {
 	if (_seconds < 0) {
 		t += _seconds;
diff --git a/src/lib/delay_line.h b/src/lib/delay_line.h
index 90f1dcfa7..781dce88a 100644
--- a/src/lib/delay_line.h
+++ b/src/lib/delay_line.h
@@ -26,8 +26,8 @@ class DelayLine : public TimedAudioVideoProcessor
 public:
 	DelayLine (boost::shared_ptr<Log> log, double);
 	
-	void process_video (boost::shared_ptr<Image>, bool, boost::shared_ptr<Subtitle>, double);
-	void process_audio (boost::shared_ptr<AudioBuffers>, double);
+	void process_video (boost::shared_ptr<const Image>, bool, boost::shared_ptr<Subtitle>, double);
+	void process_audio (boost::shared_ptr<const AudioBuffers>, double);
 
 private:
 	double _seconds;
diff --git a/src/lib/encoder.cc b/src/lib/encoder.cc
index 7b338407e..7a1eea069 100644
--- a/src/lib/encoder.cc
+++ b/src/lib/encoder.cc
@@ -231,7 +231,7 @@ Encoder::frame_done ()
 }
 
 void
-Encoder::process_video (shared_ptr<Image> image, bool same, boost::shared_ptr<Subtitle> sub)
+Encoder::process_video (shared_ptr<const Image> image, bool same, boost::shared_ptr<Subtitle> sub)
 {
 	FrameRateConversion frc (_film->source_frame_rate(), _film->dcp_frame_rate());
 	
@@ -294,7 +294,7 @@ Encoder::process_video (shared_ptr<Image> image, bool same, boost::shared_ptr<Su
 }
 
 void
-Encoder::process_audio (shared_ptr<AudioBuffers> data)
+Encoder::process_audio (shared_ptr<const AudioBuffers> data)
 {
 #if HAVE_SWRESAMPLE
 	/* Maybe sample-rate convert */
diff --git a/src/lib/encoder.h b/src/lib/encoder.h
index 86880bc34..70e81a7e0 100644
--- a/src/lib/encoder.h
+++ b/src/lib/encoder.h
@@ -73,10 +73,10 @@ public:
 	 *  @param same true if i is the same as the last time we were called.
 	 *  @param s A subtitle that should be on this frame, or 0.
 	 */
-	void process_video (boost::shared_ptr<Image> i, bool same, boost::shared_ptr<Subtitle> s);
+	void process_video (boost::shared_ptr<const Image> i, bool same, boost::shared_ptr<Subtitle> s);
 
 	/** Call with some audio data */
-	void process_audio (boost::shared_ptr<AudioBuffers>);
+	void process_audio (boost::shared_ptr<const AudioBuffers>);
 
 	/** Called when a processing run has finished */
 	virtual void process_end ();
diff --git a/src/lib/gain.cc b/src/lib/gain.cc
index df7011d2e..ccd779d71 100644
--- a/src/lib/gain.cc
+++ b/src/lib/gain.cc
@@ -30,7 +30,7 @@ Gain::Gain (shared_ptr<Log> log, float gain)
 }
 
 void
-Gain::process_audio (shared_ptr<AudioBuffers> b)
+Gain::process_audio (shared_ptr<const AudioBuffers> b)
 {
 	if (_gain != 0) {
 		float const linear_gain = pow (10, _gain / 20);
diff --git a/src/lib/gain.h b/src/lib/gain.h
index d462e5aee..61fef5e85 100644
--- a/src/lib/gain.h
+++ b/src/lib/gain.h
@@ -24,7 +24,7 @@ class Gain : public AudioProcessor
 public:
 	Gain (boost::shared_ptr<Log> log, float gain);
 
-	void process_audio (boost::shared_ptr<AudioBuffers>);
+	void process_audio (boost::shared_ptr<const AudioBuffers>);
 
 private:
 	float _gain;
diff --git a/src/lib/image.cc b/src/lib/image.cc
index 2355d22e5..9bcbb87ab 100644
--- a/src/lib/image.cc
+++ b/src/lib/image.cc
@@ -583,6 +583,12 @@ SimpleImage::aligned () const
 	return _aligned;
 }
 
+shared_ptr<Image>
+SimpleImage::clone () const
+{
+	return shared_ptr<Image> (new SimpleImage (*this));
+}
+
 FilterBufferImage::FilterBufferImage (AVPixelFormat p, AVFilterBufferRef* b)
 	: Image (p)
 	, _buffer (b)
diff --git a/src/lib/image.h b/src/lib/image.h
index 6b9ade99e..31035d272 100644
--- a/src/lib/image.h
+++ b/src/lib/image.h
@@ -70,6 +70,8 @@ public:
 
 	virtual bool aligned () const = 0;
 
+	virtual boost::shared_ptr<Image> clone () const = 0;
+
 	int components () const;
 	int lines (int) const;
 
@@ -118,6 +120,9 @@ private:
 	/* Not allowed */
 	FilterBufferImage (FilterBufferImage const &);
 	FilterBufferImage& operator= (FilterBufferImage const &);
+	boost::shared_ptr<Image> clone () const {
+		assert (false);
+	}
 	
 	AVFilterBufferRef* _buffer;
 	int* _line_size;
@@ -139,6 +144,7 @@ public:
 	int * stride () const;
 	libdcp::Size size () const;
 	bool aligned () const;
+	boost::shared_ptr<Image> clone () const;
 
 protected:
 	void allocate ();
diff --git a/src/lib/matcher.cc b/src/lib/matcher.cc
index dd0312f67..9924c003a 100644
--- a/src/lib/matcher.cc
+++ b/src/lib/matcher.cc
@@ -41,7 +41,7 @@ Matcher::Matcher (shared_ptr<Log> log, int sample_rate, float frames_per_second)
 }
 
 void
-Matcher::process_video (boost::shared_ptr<Image> image, bool same, boost::shared_ptr<Subtitle> sub, double t)
+Matcher::process_video (boost::shared_ptr<const Image> image, bool same, boost::shared_ptr<Subtitle> sub, double t)
 {
 	_pixel_format = image->pixel_format ();
 	_size = image->size ();
@@ -90,7 +90,7 @@ Matcher::process_video (boost::shared_ptr<Image> image, bool same, boost::shared
 }
 
 void
-Matcher::process_audio (boost::shared_ptr<AudioBuffers> b, double t)
+Matcher::process_audio (boost::shared_ptr<const AudioBuffers> b, double t)
 {
 	_channels = b->channels ();
 
@@ -202,8 +202,9 @@ void
 Matcher::repeat_last_video ()
 {
 	if (!_last_image) {
-		_last_image.reset (new SimpleImage (_pixel_format.get(), _size.get(), true));
-		_last_image->make_black ();
+		shared_ptr<Image> im (new SimpleImage (_pixel_format.get(), _size.get(), true));
+		im->make_black ();
+		_last_image = im;
 	}
 
 	Video (_last_image, true, _last_subtitle);
diff --git a/src/lib/matcher.h b/src/lib/matcher.h
index f54aa4b6a..41aa373a4 100644
--- a/src/lib/matcher.h
+++ b/src/lib/matcher.h
@@ -25,8 +25,8 @@ class Matcher : public Processor, public TimedAudioSink, public TimedVideoSink,
 {
 public:
 	Matcher (boost::shared_ptr<Log> log, int sample_rate, float frames_per_second);
-	void process_video (boost::shared_ptr<Image> i, bool, boost::shared_ptr<Subtitle> s, double);
-	void process_audio (boost::shared_ptr<AudioBuffers>, double);
+	void process_video (boost::shared_ptr<const Image> i, bool, boost::shared_ptr<Subtitle> s, double);
+	void process_audio (boost::shared_ptr<const AudioBuffers>, double);
 	void process_end ();
 
 private:
@@ -43,19 +43,19 @@ private:
 	boost::optional<int> _channels;
 
 	struct AudioRecord {
-		AudioRecord (boost::shared_ptr<AudioBuffers> a, double t)
+		AudioRecord (boost::shared_ptr<const AudioBuffers> a, double t)
 			: audio (a)
 			, time (t)
 		{}
 		
-		boost::shared_ptr<AudioBuffers> audio;
+		boost::shared_ptr<const AudioBuffers> audio;
 		double time;
 	};
 
 	std::list<AudioRecord> _pending_audio;
 
 	boost::optional<double> _first_input;
-	boost::shared_ptr<Image> _last_image;
+	boost::shared_ptr<const Image> _last_image;
 	boost::shared_ptr<Subtitle> _last_subtitle;
 
 	bool _had_first_video;
diff --git a/src/lib/trimmer.cc b/src/lib/trimmer.cc
index 68364e50a..39ec44fcb 100644
--- a/src/lib/trimmer.cc
+++ b/src/lib/trimmer.cc
@@ -56,7 +56,7 @@ Trimmer::Trimmer (
 }
 
 void
-Trimmer::process_video (shared_ptr<Image> image, bool same, shared_ptr<Subtitle> sub)
+Trimmer::process_video (shared_ptr<const Image> image, bool same, shared_ptr<Subtitle> sub)
 {
 	if (_video_in >= _video_start && _video_in <= _video_end) {
 		Video (image, same, sub);
@@ -66,7 +66,7 @@ Trimmer::process_video (shared_ptr<Image> image, bool same, shared_ptr<Subtitle>
 }
 
 void
-Trimmer::process_audio (shared_ptr<AudioBuffers> audio)
+Trimmer::process_audio (shared_ptr<const AudioBuffers> audio)
 {
 	int64_t offset = _audio_start - _audio_in;
 	if (offset > audio->frames()) {
@@ -91,8 +91,10 @@ Trimmer::process_audio (shared_ptr<AudioBuffers> audio)
 	_audio_in += audio->frames ();
 	
 	if (offset != 0 || length != audio->frames ()) {
-		audio->move (offset, 0, length);
-		audio->set_frames (length);
+		shared_ptr<AudioBuffers> copy (new AudioBuffers (audio));
+		copy->move (offset, 0, length);
+		copy->set_frames (length);
+		audio = copy;
 	}
 	
 	Audio (audio);
diff --git a/src/lib/trimmer.h b/src/lib/trimmer.h
index ff7e9514d..45b3f149a 100644
--- a/src/lib/trimmer.h
+++ b/src/lib/trimmer.h
@@ -24,8 +24,8 @@ class Trimmer : public AudioVideoProcessor
 public:
 	Trimmer (boost::shared_ptr<Log>, int, int, int, int, float, int);
 
-	void process_video (boost::shared_ptr<Image> i, bool, boost::shared_ptr<Subtitle> s);
-	void process_audio (boost::shared_ptr<AudioBuffers>);
+	void process_video (boost::shared_ptr<const Image> i, bool, boost::shared_ptr<Subtitle> s);
+	void process_audio (boost::shared_ptr<const AudioBuffers>);
 
 private:
 	friend class trimmer_test;
diff --git a/src/lib/util.cc b/src/lib/util.cc
index e43b598ab..859aa6de7 100644
--- a/src/lib/util.cc
+++ b/src/lib/util.cc
@@ -63,11 +63,24 @@ extern "C" {
 
 #include "i18n.h"
 
-using namespace std;
-using namespace boost;
+using std::cout;
+using std::string;
+using std::stringstream;
+using std::list;
+using std::ostream;
+using std::vector;
+using std::ifstream;
+using std::istream;
+using std::min;
+using std::max;
+using std::multimap;
+using std::pair;
+using boost::shared_ptr;
+using boost::lexical_cast;
+using boost::optional;
 using libdcp::Size;
 
-thread::id ui_thread;
+boost::thread::id ui_thread;
 
 /** Convert some number of seconds to a string representation
  *  in hours, minutes and seconds.
@@ -87,9 +100,9 @@ seconds_to_hms (int s)
 	stringstream hms;
 	hms << h << N_(":");
 	hms.width (2);
-	hms << setfill ('0') << m << N_(":");
+	hms << std::setfill ('0') << m << N_(":");
 	hms.width (2);
-	hms << setfill ('0') << s;
+	hms << std::setfill ('0') << s;
 
 	return hms.str ();
 }
@@ -185,7 +198,7 @@ stacktrace (ostream& out, int levels)
      
 	if (strings) {
 		for (i = 0; i < size && (levels == 0 || i < size_t(levels)); i++) {
-			out << N_("  ") << demangle (strings[i]) << endl;
+			out << N_("  ") << demangle (strings[i]) << "\n";
 		}
 		
 		free (strings);
@@ -243,7 +256,7 @@ dvdomatic_setup ()
 	Filter::setup_filters ();
 	SoundProcessor::setup_sound_processors ();
 
-	ui_thread = this_thread::get_id ();
+	ui_thread = boost::this_thread::get_id ();
 }
 
 #ifdef DVDOMATIC_WINDOWS
@@ -338,7 +351,7 @@ md5_digest (void const * data, int size)
 	
 	stringstream s;
 	for (int i = 0; i < MD5_DIGEST_LENGTH; ++i) {
-		s << hex << setfill('0') << setw(2) << ((int) digest[i]);
+		s << std::hex << std::setfill('0') << std::setw(2) << ((int) digest[i]);
 	}
 
 	return s.str ();
@@ -350,14 +363,14 @@ md5_digest (void const * data, int size)
 string
 md5_digest (string file)
 {
-	ifstream f (file.c_str(), ios::binary);
+	ifstream f (file.c_str(), std::ios::binary);
 	if (!f.good ()) {
 		throw OpenFileError (file);
 	}
 	
-	f.seekg (0, ios::end);
+	f.seekg (0, std::ios::end);
 	int bytes = f.tellg ();
-	f.seekg (0, ios::beg);
+	f.seekg (0, std::ios::beg);
 
 	int const buffer_size = 64 * 1024;
 	char buffer[buffer_size];
@@ -376,7 +389,7 @@ md5_digest (string file)
 
 	stringstream s;
 	for (int i = 0; i < MD5_DIGEST_LENGTH; ++i) {
-		s << hex << setfill('0') << setw(2) << ((int) digest[i]);
+		s << std::hex << std::setfill('0') << std::setw(2) << ((int) digest[i]);
 	}
 
 	return s.str ();
@@ -441,8 +454,8 @@ best_dcp_frame_rate (float source_fps)
 	}
 
 	/* Pick the best one, bailing early if we hit an exact match */
-	float error = numeric_limits<float>::max ();
-	boost::optional<FrameRateCandidate> best;
+	float error = std::numeric_limits<float>::max ();
+	optional<FrameRateCandidate> best;
 	list<FrameRateCandidate>::iterator i = candidates.begin();
 	while (i != candidates.end()) {
 		
@@ -509,16 +522,16 @@ Socket::Socket (int timeout)
 	, _socket (_io_service)
 	, _timeout (timeout)
 {
-	_deadline.expires_at (posix_time::pos_infin);
+	_deadline.expires_at (boost::posix_time::pos_infin);
 	check ();
 }
 
 void
 Socket::check ()
 {
-	if (_deadline.expires_at() <= asio::deadline_timer::traits_type::now ()) {
+	if (_deadline.expires_at() <= boost::asio::deadline_timer::traits_type::now ()) {
 		_socket.close ();
-		_deadline.expires_at (posix_time::pos_infin);
+		_deadline.expires_at (boost::posix_time::pos_infin);
 	}
 
 	_deadline.async_wait (boost::bind (&Socket::check, this));
@@ -528,14 +541,14 @@ Socket::check ()
  *  @param endpoint End-point to connect to.
  */
 void
-Socket::connect (asio::ip::basic_resolver_entry<asio::ip::tcp> const & endpoint)
+Socket::connect (boost::asio::ip::basic_resolver_entry<boost::asio::ip::tcp> const & endpoint)
 {
-	_deadline.expires_from_now (posix_time::seconds (_timeout));
-	system::error_code ec = asio::error::would_block;
-	_socket.async_connect (endpoint, lambda::var(ec) = lambda::_1);
+	_deadline.expires_from_now (boost::posix_time::seconds (_timeout));
+	boost::system::error_code ec = boost::asio::error::would_block;
+	_socket.async_connect (endpoint, boost::lambda::var(ec) = boost::lambda::_1);
 	do {
 		_io_service.run_one();
-	} while (ec == asio::error::would_block);
+	} while (ec == boost::asio::error::would_block);
 
 	if (ec || !_socket.is_open ()) {
 		throw NetworkError (_("connect timed out"));
@@ -549,14 +562,14 @@ Socket::connect (asio::ip::basic_resolver_entry<asio::ip::tcp> const & endpoint)
 void
 Socket::write (uint8_t const * data, int size)
 {
-	_deadline.expires_from_now (posix_time::seconds (_timeout));
-	system::error_code ec = asio::error::would_block;
+	_deadline.expires_from_now (boost::posix_time::seconds (_timeout));
+	boost::system::error_code ec = boost::asio::error::would_block;
 
-	asio::async_write (_socket, asio::buffer (data, size), lambda::var(ec) = lambda::_1);
+	boost::asio::async_write (_socket, boost::asio::buffer (data, size), boost::lambda::var(ec) = boost::lambda::_1);
 	
 	do {
 		_io_service.run_one ();
-	} while (ec == asio::error::would_block);
+	} while (ec == boost::asio::error::would_block);
 
 	if (ec) {
 		throw NetworkError (ec.message ());
@@ -577,14 +590,14 @@ Socket::write (uint32_t v)
 void
 Socket::read (uint8_t* data, int size)
 {
-	_deadline.expires_from_now (posix_time::seconds (_timeout));
-	system::error_code ec = asio::error::would_block;
+	_deadline.expires_from_now (boost::posix_time::seconds (_timeout));
+	boost::system::error_code ec = boost::asio::error::would_block;
 
-	asio::async_read (_socket, asio::buffer (data, size), lambda::var(ec) = lambda::_1);
+	boost::asio::async_read (_socket, boost::asio::buffer (data, size), boost::lambda::var(ec) = boost::lambda::_1);
 
 	do {
 		_io_service.run_one ();
-	} while (ec == asio::error::would_block);
+	} while (ec == boost::asio::error::would_block);
 	
 	if (ec) {
 		throw NetworkError (ec.message ());
@@ -761,6 +774,21 @@ AudioBuffers::AudioBuffers (AudioBuffers const & other)
 	}
 }
 
+/* XXX: it's a shame that this is a copy-and-paste of the above;
+   probably fixable with c++0x.
+*/
+AudioBuffers::AudioBuffers (boost::shared_ptr<const AudioBuffers> other)
+	: _channels (other->_channels)
+	, _frames (other->_frames)
+	, _allocated_frames (other->_frames)
+{
+	_data = new float*[_channels];
+	for (int i = 0; i < _channels; ++i) {
+		_data[i] = new float[_frames];
+		memcpy (_data[i], other->_data[i], _frames * sizeof (float));
+	}
+}
+
 /** AudioBuffers destructor */
 AudioBuffers::~AudioBuffers ()
 {
@@ -865,7 +893,7 @@ AudioBuffers::move (int from, int to, int frames)
 void
 ensure_ui_thread ()
 {
-	assert (this_thread::get_id() == ui_thread);
+	assert (boost::this_thread::get_id() == ui_thread);
 }
 
 /** @param v Source video frame.
diff --git a/src/lib/util.h b/src/lib/util.h
index 31d0fc967..99670110e 100644
--- a/src/lib/util.h
+++ b/src/lib/util.h
@@ -241,6 +241,7 @@ class AudioBuffers
 public:
 	AudioBuffers (int channels, int frames);
 	AudioBuffers (AudioBuffers const &);
+	AudioBuffers (boost::shared_ptr<const AudioBuffers>);
 	~AudioBuffers ();
 
 	float** data () const {
diff --git a/src/lib/video_sink.h b/src/lib/video_sink.h
index 32c7f3b38..0170c7350 100644
--- a/src/lib/video_sink.h
+++ b/src/lib/video_sink.h
@@ -34,7 +34,7 @@ public:
 	 *  @param same true if i is the same as last time we were called.
 	 *  @param s A subtitle that should be on this frame, or 0.
 	 */
-	virtual void process_video (boost::shared_ptr<Image> i, bool same, boost::shared_ptr<Subtitle> s) = 0;
+	virtual void process_video (boost::shared_ptr<const Image> i, bool same, boost::shared_ptr<Subtitle> s) = 0;
 };
 
 class TimedVideoSink
@@ -46,7 +46,7 @@ public:
 	 *  @param s A subtitle that should be on this frame, or 0.
 	 *  @param t Source timestamp.
 	 */
-	virtual void process_video (boost::shared_ptr<Image> i, bool same, boost::shared_ptr<Subtitle> s, double t) = 0;
+	virtual void process_video (boost::shared_ptr<const Image> i, bool same, boost::shared_ptr<Subtitle> s, double t) = 0;
 };
 
 #endif
diff --git a/src/lib/video_source.h b/src/lib/video_source.h
index e4a8ab058..748cb6fe9 100644
--- a/src/lib/video_source.h
+++ b/src/lib/video_source.h
@@ -45,7 +45,7 @@ public:
 	 *  Second parameter is true if the image is the same as the last one that was emitted.
 	 *  Third parameter is either 0 or a subtitle that should be on this frame.
 	 */
-	boost::signals2::signal<void (boost::shared_ptr<Image>, bool, boost::shared_ptr<Subtitle>)> Video;
+	boost::signals2::signal<void (boost::shared_ptr<const Image>, bool, boost::shared_ptr<Subtitle>)> Video;
 
 	void connect_video (boost::shared_ptr<VideoSink>);
 };
@@ -63,7 +63,7 @@ public:
 	 *  Third parameter is either 0 or a subtitle that should be on this frame.
 	 *  Fourth parameter is the source timestamp of this frame.
 	 */
-	boost::signals2::signal<void (boost::shared_ptr<Image>, bool, boost::shared_ptr<Subtitle>, double)> Video;
+	boost::signals2::signal<void (boost::shared_ptr<const Image>, bool, boost::shared_ptr<Subtitle>, double)> Video;
 
 	void connect_video (boost::shared_ptr<VideoSink>);
 	void connect_video (boost::shared_ptr<TimedVideoSink>);