Tests pass again.

18 files changed, 186 insertions, 132 deletions

diff --git a/src/lib/decoder.cc b/src/lib/decoder.cc
index e91b5e19e..8e1e4e3c5 100644
--- a/src/lib/decoder.cc
+++ b/src/lib/decoder.cc
@@ -73,57 +73,19 @@ Decoder::go ()
 	}
 }
 
-/** Called to tell the world that some audio data is ready
- *  @param audio Audio data.
- */
-void
-Decoder::process_audio (shared_ptr<AudioBuffers> audio)
-{
-	/* Maybe apply gain */
-	if (_film->audio_gain() != 0) {
-		float const linear_gain = pow (10, _film->audio_gain() / 20);
-		for (int i = 0; i < audio->channels(); ++i) {
-			for (int j = 0; j < audio->frames(); ++j) {
-				audio->data(i)[j] *= linear_gain;
-			}
-		}
-	}
-
-	Audio (audio);
-}
-
 /** Called by subclasses to tell the world that some video data is ready.
  *  We do some post-processing / filtering then emit it for listeners.
  *  @param frame to decode; caller manages memory.
  */
 void
-Decoder::process_video (AVFrame const * frame)
+Decoder::emit_video (shared_ptr<Image> image)
 {
-	shared_ptr<FilterGraph> graph;
-
-	list<shared_ptr<FilterGraph> >::iterator i = _filter_graphs.begin();
-	while (i != _filter_graphs.end() && !(*i)->can_process (Size (frame->width, frame->height), (AVPixelFormat) frame->format)) {
-		++i;
-	}
-
-	if (i == _filter_graphs.end ()) {
-		graph.reset (new FilterGraph (_film, this, _opt->apply_crop, Size (frame->width, frame->height), (AVPixelFormat) frame->format));
-		_filter_graphs.push_back (graph);
-		_film->log()->log (String::compose ("New graph for %1x%2, pixel format %3", frame->width, frame->height, frame->format));
-	} else {
-		graph = *i;
+	shared_ptr<Subtitle> sub;
+	if (_timed_subtitle && _timed_subtitle->displayed_at (double (video_frame()) / _film->frames_per_second())) {
+		sub = _timed_subtitle->subtitle ();
 	}
 
-	list<shared_ptr<Image> > images = graph->process (frame);
-
-	for (list<shared_ptr<Image> >::iterator i = images.begin(); i != images.end(); ++i) {
-		shared_ptr<Subtitle> sub;
-		if (_timed_subtitle && _timed_subtitle->displayed_at (double (video_frame()) / _film->frames_per_second())) {
-			sub = _timed_subtitle->subtitle ();
-		}
-
-		emit_video (*i, sub);
-	}
+	Video (image, sub);
 }
 
 void
@@ -149,7 +111,7 @@ Decoder::emit_video (shared_ptr<Image> image, shared_ptr<Subtitle> sub)
 }
 
 void
-Decoder::process_subtitle (shared_ptr<TimedSubtitle> s)
+Decoder::emit_subtitle (shared_ptr<TimedSubtitle> s)
 {
 	_timed_subtitle = s;
 	
diff --git a/src/lib/decoder.h b/src/lib/decoder.h
index a458c348b..5bb5b574d 100644
--- a/src/lib/decoder.h
+++ b/src/lib/decoder.h
@@ -99,9 +99,8 @@ protected:
 	
 	virtual PixelFormat pixel_format () const = 0;
 	
-	void process_video (AVFrame const *);
-	void process_audio (boost::shared_ptr<AudioBuffers>);
-	void process_subtitle (boost::shared_ptr<TimedSubtitle>);
+	void emit_video (boost::shared_ptr<Image>);
+	void emit_subtitle (boost::shared_ptr<TimedSubtitle>);
 	void repeat_last_video ();
 
 	/** our Film */
@@ -122,8 +121,6 @@ private:
 
 	SourceFrame _video_frame;
 
-	std::list<boost::shared_ptr<FilterGraph> > _filter_graphs;
-
 	boost::shared_ptr<TimedSubtitle> _timed_subtitle;
 
 	boost::shared_ptr<Image> _last_image;
diff --git a/src/lib/ffmpeg_decoder.cc b/src/lib/ffmpeg_decoder.cc
index 78d0c48c4..3767d7c5f 100644
--- a/src/lib/ffmpeg_decoder.cc
+++ b/src/lib/ffmpeg_decoder.cc
@@ -47,12 +47,14 @@ extern "C" {
 #include "util.h"
 #include "log.h"
 #include "ffmpeg_decoder.h"
+#include "filter_graph.h"
 #include "subtitle.h"
 
 using std::cout;
 using std::string;
 using std::vector;
 using std::stringstream;
+using std::list;
 using boost::shared_ptr;
 using boost::optional;
 
@@ -223,7 +225,7 @@ FFmpegDecoder::pass ()
 		int frame_finished;
 
 		while (avcodec_decode_video2 (_video_codec_context, _frame, &frame_finished, &_packet) >= 0 && frame_finished) {
-			process_video (_frame);
+			filter_and_emit_video (_frame);
 		}
 
 		if (_audio_stream && _opt->decode_audio && _film->use_content_audio()) {
@@ -233,7 +235,7 @@ FFmpegDecoder::pass ()
 					);
 
 				assert (_audio_codec_context->channels == _film->audio_channels());
-				process_audio (deinterleave_audio (_frame->data[0], data_size));
+				Audio (deinterleave_audio (_frame->data[0], data_size));
 			}
 		}
 
@@ -283,7 +285,7 @@ FFmpegDecoder::pass ()
 
 			if (delta > -one_frame) {
 				/* Process this frame */
-				process_video (_frame);
+				filter_and_emit_video (_frame);
 			} else {
 				/* Otherwise we are omitting a frame to keep things right */
 				_film->log()->log (String::compose ("Frame removed at %1s", out_pts_seconds));
@@ -326,7 +328,7 @@ FFmpegDecoder::pass ()
 					if (s) {
 						shared_ptr<AudioBuffers> audio (new AudioBuffers (_audio_stream.get().channels(), s));
 						audio->make_silent ();
-						process_audio (audio);
+						Audio (audio);
 					}
 				}
 
@@ -335,7 +337,7 @@ FFmpegDecoder::pass ()
 					);
 				
 				assert (_audio_codec_context->channels == _film->audio_channels());
-				process_audio (deinterleave_audio (_frame->data[0], data_size));
+				Audio (deinterleave_audio (_frame->data[0], data_size));
 			}
 		}
 			
@@ -348,9 +350,9 @@ FFmpegDecoder::pass ()
 			   indicate that the previous subtitle should stop.
 			*/
 			if (sub.num_rects > 0) {
-				process_subtitle (shared_ptr<TimedSubtitle> (new TimedSubtitle (sub, _first_video.get())));
+				emit_subtitle (shared_ptr<TimedSubtitle> (new TimedSubtitle (sub, _first_video.get())));
 			} else {
-				process_subtitle (shared_ptr<TimedSubtitle> ());
+				emit_subtitle (shared_ptr<TimedSubtitle> ());
 			}
 			avsubtitle_free (&sub);
 		}
@@ -527,3 +529,28 @@ FFmpegDecoder::set_subtitle_stream (optional<SubtitleStream> s)
 	Decoder::set_subtitle_stream (s);
 	setup_subtitle ();
 }
+
+void
+FFmpegDecoder::filter_and_emit_video (AVFrame* frame)
+{
+	shared_ptr<FilterGraph> graph;
+
+	list<shared_ptr<FilterGraph> >::iterator i = _filter_graphs.begin();
+	while (i != _filter_graphs.end() && !(*i)->can_process (Size (frame->width, frame->height), (AVPixelFormat) frame->format)) {
+		++i;
+	}
+
+	if (i == _filter_graphs.end ()) {
+		graph.reset (new FilterGraph (_film, this, _opt->apply_crop, Size (frame->width, frame->height), (AVPixelFormat) frame->format));
+		_filter_graphs.push_back (graph);
+		_film->log()->log (String::compose ("New graph for %1x%2, pixel format %3", frame->width, frame->height, frame->format));
+	} else {
+		graph = *i;
+	}
+
+	list<shared_ptr<Image> > images = graph->process (frame);
+
+	for (list<shared_ptr<Image> >::iterator i = images.begin(); i != images.end(); ++i) {
+		emit_video (*i);
+	}
+}
diff --git a/src/lib/ffmpeg_decoder.h b/src/lib/ffmpeg_decoder.h
index 856ac0801..5c6f8ab26 100644
--- a/src/lib/ffmpeg_decoder.h
+++ b/src/lib/ffmpeg_decoder.h
@@ -58,6 +58,10 @@ public:
 	/* Methods to query our input video */
 	float frames_per_second () const;
 	Size native_size () const;
+	int time_base_numerator () const;
+	int time_base_denominator () const;
+	int sample_aspect_ratio_numerator () const;
+	int sample_aspect_ratio_denominator () const;
 
 	void set_audio_stream (boost::optional<AudioStream>);
 	void set_subtitle_stream (boost::optional<SubtitleStream>);
@@ -66,13 +70,11 @@ private:
 
 	bool pass ();
 	PixelFormat pixel_format () const;
-	int time_base_numerator () const;
-	int time_base_denominator () const;
-	int sample_aspect_ratio_numerator () const;
-	int sample_aspect_ratio_denominator () const;
 	AVSampleFormat audio_sample_format () const;
 	int bytes_per_audio_sample () const;
 
+	void filter_and_emit_video (AVFrame *);
+
 	void setup_general ();
 	void setup_video ();
 	void setup_audio ();
@@ -99,4 +101,6 @@ private:
 
 	boost::optional<double> _first_video;
 	boost::optional<double> _first_audio;
+
+	std::list<boost::shared_ptr<FilterGraph> > _filter_graphs;
 };
diff --git a/src/lib/filter_graph.cc b/src/lib/filter_graph.cc
index 72bb8deb7..aaa9e07ba 100644
--- a/src/lib/filter_graph.cc
+++ b/src/lib/filter_graph.cc
@@ -28,42 +28,36 @@ extern "C" {
 #endif
 #include <libavformat/avio.h>
 }
-#include "film.h"
 #include "decoder.h"
 #include "filter_graph.h"
 #include "ffmpeg_compatibility.h"
 #include "filter.h"
 #include "exceptions.h"
 #include "image.h"
+#include "film.h"
+#include "ffmpeg_decoder.h"
 
 using std::stringstream;
 using std::string;
 using std::list;
 using boost::shared_ptr;
 
-FilterGraph::FilterGraph (shared_ptr<Film> film, Decoder* decoder, bool crop, Size s, AVPixelFormat p)
+FilterGraph::FilterGraph (shared_ptr<Film> film, FFmpegDecoder* decoder, bool crop, Size s, AVPixelFormat p)
 	: _buffer_src_context (0)
 	, _buffer_sink_context (0)
 	, _size (s)
 	, _pixel_format (p)
 {
-	stringstream fs;
-	Size size_after_crop;
-	
-	if (crop) {
-		size_after_crop = film->cropped_size (decoder->native_size ());
-		fs << crop_string (Position (film->crop().left, film->crop().top), size_after_crop);
-	} else {
-		size_after_crop = decoder->native_size ();
-		fs << crop_string (Position (0, 0), size_after_crop);
-	}
-
 	string filters = Filter::ffmpeg_strings (film->filters()).first;
 	if (!filters.empty ()) {
 		filters += ",";
 	}
 
-	filters += fs.str ();
+	if (crop) {
+		filters += crop_string (Position (film->crop().left, film->crop().top), film->cropped_size (decoder->native_size()));
+	} else {
+		filters += crop_string (Position (0, 0), decoder->native_size());
+	}
 
 	avfilter_register_all ();
 	
diff --git a/src/lib/filter_graph.h b/src/lib/filter_graph.h
index 4ff10dece..5c0c83d16 100644
--- a/src/lib/filter_graph.h
+++ b/src/lib/filter_graph.h
@@ -22,14 +22,14 @@
 
 #include "util.h"
 
-class Decoder;
 class Image;
-class Film;
+class VideoFilter;
+class FFmpegDecoder;
 
 class FilterGraph
 {
 public:
-	FilterGraph (boost::shared_ptr<Film> film, Decoder* decoder, bool crop, Size s, AVPixelFormat p);
+	FilterGraph (boost::shared_ptr<Film> film, FFmpegDecoder* decoder, bool crop, Size s, AVPixelFormat p);
 
 	bool can_process (Size s, AVPixelFormat p) const;
 	std::list<boost::shared_ptr<Image> > process (AVFrame const * frame);
diff --git a/src/lib/gain.cc b/src/lib/gain.cc
new file mode 100644
index 000000000..80d3b7c72
--- /dev/null
+++ b/src/lib/gain.cc
@@ -0,0 +1,26 @@
+#include "gain.h"
+
+using boost::shared_ptr;
+
+/** @param gain gain in dB */
+Gain::Gain (Log* log, float gain)
+	: AudioProcessor (log)
+	, _gain (gain)
+{
+
+}
+
+void
+Gain::process_audio (shared_ptr<AudioBuffers> b)
+{
+	if (_gain != 0) {
+		float const linear_gain = pow (10, _gain / 20);
+		for (int i = 0; i < b->channels(); ++i) {
+			for (int j = 0; j < b->frames(); ++j) {
+				b->data(i)[j] *= linear_gain;
+			}
+		}
+	}
+
+	Audio (b);
+}
diff --git a/src/lib/gain.h b/src/lib/gain.h
new file mode 100644
index 000000000..c1221ed48
--- /dev/null
+++ b/src/lib/gain.h
@@ -0,0 +1,12 @@
+#include "processor.h"
+
+class Gain : public AudioProcessor
+{
+public:
+	Gain (Log* log, float gain);
+
+	void process_audio (boost::shared_ptr<AudioBuffers>);
+
+private:
+	float _gain;
+};
diff --git a/src/lib/image.cc b/src/lib/image.cc
index 05270954d..4f818b739 100644
--- a/src/lib/image.cc
+++ b/src/lib/image.cc
@@ -293,7 +293,7 @@ Image::write_to_socket (shared_ptr<Socket> socket) const
  *  @param p Pixel format.
  *  @param s Size in pixels.
  */
-SimpleImage::SimpleImage (AVPixelFormat p, Size s, function<int (int)> rounder)
+SimpleImage::SimpleImage (AVPixelFormat p, Size s, function<int (int, int const *)> stride_computer)
 	: Image (p)
 	, _size (s)
 {
@@ -329,7 +329,7 @@ SimpleImage::SimpleImage (AVPixelFormat p, Size s, function<int (int)> rounder)
 	}
 
 	for (int i = 0; i < components(); ++i) {
-		_stride[i] = rounder (_line_size[i]);
+		_stride[i] = stride_computer (i, _line_size);
 		_data[i] = (uint8_t *) av_malloc (_stride[i] * lines (i));
 	}
 }
@@ -371,19 +371,13 @@ SimpleImage::size () const
 }
 
 AlignedImage::AlignedImage (AVPixelFormat f, Size s)
-	: SimpleImage (f, s, boost::bind (round_up, _1, 32))
+	: SimpleImage (f, s, boost::bind (stride_round_up, _1, _2, 32))
 {
 
 }
 
-CompactImage::CompactImage (AVPixelFormat f, Size s)
-	: SimpleImage (f, s, boost::bind (round_up, _1, 1))
-{
-	setup_picture ();
-}
-
-CompactImage::CompactImage (shared_ptr<Image> im)
-	: SimpleImage (im->pixel_format(), im->size(), boost::bind (round_up, _1, 1))
+AlignedImage::AlignedImage (shared_ptr<Image> im)
+	: SimpleImage (im->pixel_format(), im->size(), boost::bind (stride_round_up, _1, _2, 1))
 {
 	assert (components() == im->components());
 
@@ -400,16 +394,31 @@ CompactImage::CompactImage (shared_ptr<Image> im)
 			o += im->stride()[c];
 		}
 	}
+}
+
+CompactImage::CompactImage (AVPixelFormat f, Size s)
+	: SimpleImage (f, s, boost::bind (stride_round_up, _1, _2, 1))
+{
 
-	setup_picture ();
 }
 
-void
-CompactImage::setup_picture ()
+CompactImage::CompactImage (shared_ptr<Image> im)
+	: SimpleImage (im->pixel_format(), im->size(), boost::bind (stride_round_up, _1, _2, 1))
 {
+	assert (components() == im->components());
+
 	for (int c = 0; c < components(); ++c) {
-		_picture.data[c] = data()[c];
-		_picture.linesize[c] = line_size()[c];
+
+		assert (line_size()[c] == im->line_size()[c]);
+
+		uint8_t* t = data()[c];
+		uint8_t* o = im->data()[c];
+		
+		for (int y = 0; y < lines(c); ++y) {
+			memcpy (t, o, line_size()[c]);
+			t += stride()[c];
+			o += im->stride()[c];
+		}
 	}
 }
 
diff --git a/src/lib/image.h b/src/lib/image.h
index bb4a32319..69f3a8837 100644
--- a/src/lib/image.h
+++ b/src/lib/image.h
@@ -111,7 +111,7 @@ private:
 class SimpleImage : public Image
 {
 public:
-	SimpleImage (AVPixelFormat, Size, boost::function<int (int)> rounder);
+	SimpleImage (AVPixelFormat, Size, boost::function<int (int, int const *)> rounder);
 	~SimpleImage ();
 
 	uint8_t ** data () const;
@@ -131,6 +131,7 @@ class AlignedImage : public SimpleImage
 {
 public:
 	AlignedImage (AVPixelFormat, Size);
+	AlignedImage (boost::shared_ptr<Image>);
 };
 
 class CompactImage : public SimpleImage
@@ -138,15 +139,6 @@ class CompactImage : public SimpleImage
 public:
 	CompactImage (AVPixelFormat, Size);
 	CompactImage (boost::shared_ptr<Image>);
-
-	AVPicture const * picture () const {
-		return &_picture;
-	}
-
-private:
-	void setup_picture ();
-	
-	AVPicture _picture;
 };
 
 #endif
diff --git a/src/lib/imagemagick_decoder.cc b/src/lib/imagemagick_decoder.cc
index fd4e5b18d..53e1db879 100644
--- a/src/lib/imagemagick_decoder.cc
+++ b/src/lib/imagemagick_decoder.cc
@@ -23,8 +23,8 @@
 #include "image.h"
 #include "film.h"
 
-using namespace std;
-using namespace boost;
+using std::cout;
+using boost::shared_ptr;
 
 ImageMagickDecoder::ImageMagickDecoder (
 	boost::shared_ptr<Film> f, boost::shared_ptr<const Options> o, Job* j)
@@ -50,9 +50,9 @@ ImageMagickDecoder::pass ()
 	}
 
 	Size size = native_size ();
-	CompactImage image (PIX_FMT_RGB24, size);
+	shared_ptr<CompactImage> image (new CompactImage (PIX_FMT_RGB24, size));
 
-	uint8_t* p = image.data()[0];
+	uint8_t* p = image->data()[0];
 	for (int y = 0; y < size.height; ++y) {
 		for (int x = 0; x < size.width; ++x) {
 			Magick::Color c = _magick_image->pixelColor (x, y);
@@ -63,7 +63,7 @@ ImageMagickDecoder::pass ()
 
 	}
 	
-	process_video ((AVFrame const *) image.picture());
+	emit_video (image);
 
 	_done = true;
 	return false;
diff --git a/src/lib/processor.h b/src/lib/processor.h
index e99ff2d4d..f7785c346 100644
--- a/src/lib/processor.h
+++ b/src/lib/processor.h
@@ -38,4 +38,12 @@ public:
 	{}
 };
 
+class VideoProcessor : public Processor, public VideoSource, public VideoSink
+{
+public:
+	VideoProcessor (Log* log)
+		: Processor (log)
+	{}
+};
+
 #endif
diff --git a/src/lib/tiff_decoder.cc b/src/lib/tiff_decoder.cc
index 7e9bda139..a58ea9974 100644
--- a/src/lib/tiff_decoder.cc
+++ b/src/lib/tiff_decoder.cc
@@ -38,8 +38,10 @@ extern "C" {
 #include "options.h"
 #include "film.h"
 
-using namespace std;
-using namespace boost;
+using std::cout;
+using std::string;
+using std::stringstream;
+using boost::shared_ptr;
 
 /** @param f Our Film.
  *  @param o Options.
@@ -50,17 +52,17 @@ TIFFDecoder::TIFFDecoder (boost::shared_ptr<Film> f, boost::shared_ptr<const Opt
 {
 	string const dir = _film->content_path ();
 	
-	if (!filesystem::is_directory (dir)) {
+	if (!boost::filesystem::is_directory (dir)) {
 		throw DecodeError ("TIFF content must be in a directory");
 	}
 
-	for (filesystem::directory_iterator i = filesystem::directory_iterator (dir); i != filesystem::directory_iterator(); ++i) {
+	for (boost::filesystem::directory_iterator i = boost::filesystem::directory_iterator (dir); i != boost::filesystem::directory_iterator(); ++i) {
 		/* Aah, the sweet smell of progress */
 #if BOOST_FILESYSTEM_VERSION == 3
-		string const ext = filesystem::path(*i).extension().string();
-		string const l = filesystem::path(*i).leaf().generic_string();
+		string const ext = boost::filesystem::path(*i).extension().string();
+		string const l = boost::filesystem::path(*i).leaf().generic_string();
 #else
-		string const ext = filesystem::path(*i).extension();
+		string const ext = boost::filesystem::path(*i).extension();
 		string const l = i->leaf ();
 #endif
 		if (ext == ".tif" || ext == ".tiff") {
@@ -71,7 +73,6 @@ TIFFDecoder::TIFFDecoder (boost::shared_ptr<Film> f, boost::shared_ptr<const Opt
 	_files.sort ();
 
 	_iter = _files.begin ();
-
 }
 
 float
@@ -147,9 +148,9 @@ TIFFDecoder::pass ()
 		throw DecodeError ("could not read TIFF data");
 	}
 
-	CompactImage image (PIX_FMT_RGB24, Size (width, height));
+	shared_ptr<CompactImage> image (new CompactImage (PIX_FMT_RGB24, Size (width, height)));
 
-	uint8_t* p = image.data()[0];
+	uint8_t* p = image->data()[0];
 	for (uint32_t y = 0; y < height; ++y) {
 		for (uint32_t x = 0; x < width; ++x) {
 			uint32_t const i = (height - y - 1) * width + x;
@@ -162,7 +163,7 @@ TIFFDecoder::pass ()
 	_TIFFfree (raster);
 	TIFFClose (t);
 
-	process_video ((AVFrame const *) image.picture ());
+	emit_video (image);
 
 	++_iter;
 	return false;
diff --git a/src/lib/transcoder.cc b/src/lib/transcoder.cc
index f53fc4001..01f54be3f 100644
--- a/src/lib/transcoder.cc
+++ b/src/lib/transcoder.cc
@@ -32,6 +32,8 @@
 #include "film.h"
 #include "matcher.h"
 #include "delay_line.h"
+#include "options.h"
+#include "gain.h"
 
 using std::string;
 using boost::shared_ptr;
@@ -49,21 +51,30 @@ Transcoder::Transcoder (shared_ptr<Film> f, shared_ptr<const Options> o, Job* j,
 {
 	assert (_encoder);
 
-	AudioStream st = f->audio_stream().get();
-
-	_matcher.reset (new Matcher (f->log(), st.sample_rate(), f->frames_per_second()));
-	_delay_line.reset (new DelayLine (f->log(), st.channels(), f->audio_delay() * st.sample_rate() / 1000));
+	if (f->audio_stream()) {
+		AudioStream st = f->audio_stream().get();
+		_matcher.reset (new Matcher (f->log(), st.sample_rate(), f->frames_per_second()));
+		_delay_line.reset (new DelayLine (f->log(), st.channels(), f->audio_delay() * st.sample_rate() / 1000));
+		_gain.reset (new Gain (f->log(), f->audio_gain()));
+	}
 
 	/* Set up the decoder to use the film's set streams */
 	_decoder->set_audio_stream (f->audio_stream ());
 	_decoder->set_subtitle_stream (f->subtitle_stream ());
 
-	_decoder->connect_video (_matcher);
-	_matcher->connect_video (_encoder);
-
-	_decoder->connect_audio (_delay_line);
-	_delay_line->connect_audio (_matcher);
-	_matcher->connect_audio (_delay_line);
+	if (_matcher) {
+		_decoder->connect_video (_matcher);
+		_matcher->connect_video (_encoder);
+	} else {
+		_decoder->connect_video (_encoder);
+	}
+	
+	if (_matcher && _delay_line) {
+		_decoder->connect_audio (_delay_line);
+		_delay_line->connect_audio (_matcher);
+		_matcher->connect_audio (_gain);
+		_gain->connect_audio (_encoder);
+	}
 }
 
 /** Run the decoder, passing its output to the encoder, until the decoder
diff --git a/src/lib/transcoder.h b/src/lib/transcoder.h
index d5597ad0e..324a72037 100644
--- a/src/lib/transcoder.h
+++ b/src/lib/transcoder.h
@@ -31,6 +31,8 @@ class Job;
 class Encoder;
 class FilmState;
 class Matcher;
+class VideoFilter;
+class Gain;
 
 /** @class Transcoder
  *  @brief A class which takes a FilmState and some Options, then uses those to transcode a Film.
@@ -59,4 +61,5 @@ protected:
 	boost::shared_ptr<Decoder> _decoder;
 	boost::shared_ptr<Matcher> _matcher;
 	boost::shared_ptr<DelayLine> _delay_line;
+	boost::shared_ptr<Gain> _gain;
 };
diff --git a/src/lib/util.cc b/src/lib/util.cc
index 219441865..5e82650a5 100644
--- a/src/lib/util.cc
+++ b/src/lib/util.cc
@@ -620,12 +620,18 @@ Rect::intersection (Rect const & other) const
  */
 
 int
-round_up (int a, int t)
+stride_round_up (int c, int const * stride, int t)
 {
-	a += (t - 1);
+	int const a = stride[c] + (t - 1);
 	return a - (a % t);
 }
 
+int
+stride_lookup (int c, int const * stride)
+{
+	return stride[c];
+}
+
 /** Read a sequence of key / value pairs from a text stream;
  *  the keys are the first words on the line, and the values are
  *  the remainder of the line following the key.  Lines beginning
diff --git a/src/lib/util.h b/src/lib/util.h
index 577b9ba1b..bb68b6273 100644
--- a/src/lib/util.h
+++ b/src/lib/util.h
@@ -170,7 +170,8 @@ extern std::string crop_string (Position, Size);
 extern int dcp_audio_sample_rate (int);
 extern DCPFrameRate dcp_frame_rate (float);
 extern std::string colour_lut_index_to_name (int index);
-extern int round_up (int, int);
+extern int stride_round_up (int, int const *, int);
+extern int stride_lookup (int c, int const * stride);
 extern std::multimap<std::string, std::string> read_key_value (std::istream& s);
 extern int get_required_int (std::multimap<std::string, std::string> const & kv, std::string k);
 extern float get_required_float (std::multimap<std::string, std::string> const & kv, std::string k);
diff --git a/src/lib/wscript b/src/lib/wscript
index 4fc839097..ef4011c5f 100644
--- a/src/lib/wscript
+++ b/src/lib/wscript
@@ -29,6 +29,7 @@ def build(bld):
     	         film.cc
 		 filter.cc
 		 format.cc
+                 gain.cc
                  image.cc
                  imagemagick_decoder.cc
                  imagemagick_encoder.cc