Basics of splitting up Decoder tree like Content.

25 files changed, 192 insertions, 119 deletions

diff --git a/src/lib/audio_decoder.cc b/src/lib/audio_decoder.cc
index 705fdbef1..7ceb9680b 100644
--- a/src/lib/audio_decoder.cc
+++ b/src/lib/audio_decoder.cc
@@ -30,13 +30,13 @@ using std::cout;
 using std::map;
 using boost::shared_ptr;
 
-AudioDecoder::AudioDecoder (shared_ptr<const AudioContent> content, bool fast, shared_ptr<Log> log)
+AudioDecoder::AudioDecoder (Decoder* parent, shared_ptr<const AudioContent> content, bool fast, shared_ptr<Log> log)
 	: _audio_content (content)
 	, _ignore_audio (false)
 	, _fast (fast)
 {
 	BOOST_FOREACH (AudioStreamPtr i, content->streams ()) {
-		_streams[i] = shared_ptr<AudioDecoderStream> (new AudioDecoderStream (_audio_content, i, this, log));
+		_streams[i] = shared_ptr<AudioDecoderStream> (new AudioDecoderStream (_audio_content, i, parent, log));
 	}
 }
 
diff --git a/src/lib/audio_decoder.h b/src/lib/audio_decoder.h
index 31d0785c6..a56847daf 100644
--- a/src/lib/audio_decoder.h
+++ b/src/lib/audio_decoder.h
@@ -37,10 +37,10 @@ class Log;
 /** @class AudioDecoder.
  *  @brief Parent class for audio decoders.
  */
-class AudioDecoder : public virtual Decoder, public boost::enable_shared_from_this<AudioDecoder>
+class AudioDecoder : public boost::enable_shared_from_this<AudioDecoder>
 {
 public:
-	AudioDecoder (boost::shared_ptr<const AudioContent>, bool fast, boost::shared_ptr<Log> log);
+	AudioDecoder (Decoder* parent, boost::shared_ptr<const AudioContent>, bool fast, boost::shared_ptr<Log> log);
 
 	/** Try to fetch some audio from a specific place in this content.
 	 *  @param frame Frame to start from (after resampling, if applicable)
@@ -56,7 +56,6 @@ public:
 		return _fast;
 	}
 
-protected:
 	void audio (AudioStreamPtr stream, boost::shared_ptr<const AudioBuffers>, ContentTime);
 	void flush ();
 	void seek (ContentTime t, bool accurate);
diff --git a/src/lib/audio_decoder_stream.cc b/src/lib/audio_decoder_stream.cc
index cd2e3a388..bbe26b6ef 100644
--- a/src/lib/audio_decoder_stream.cc
+++ b/src/lib/audio_decoder_stream.cc
@@ -39,14 +39,14 @@ using std::max;
 using boost::optional;
 using boost::shared_ptr;
 
-AudioDecoderStream::AudioDecoderStream (shared_ptr<const AudioContent> content, AudioStreamPtr stream, AudioDecoder* decoder, shared_ptr<Log> log)
+AudioDecoderStream::AudioDecoderStream (shared_ptr<const AudioContent> content, AudioStreamPtr stream, Decoder* decoder, shared_ptr<Log> log)
 	: _content (content)
 	, _stream (stream)
 	, _decoder (decoder)
 	, _log (log)
 {
 	if (content->resampled_frame_rate() != _stream->frame_rate() && _stream->channels() > 0) {
-		_resampler.reset (new Resampler (_stream->frame_rate(), content->resampled_frame_rate(), _stream->channels (), decoder->fast ()));
+		_resampler.reset (new Resampler (_stream->frame_rate(), content->resampled_frame_rate(), _stream->channels (), decoder->audio->fast ()));
 	}
 
 	reset_decoded ();
diff --git a/src/lib/audio_decoder_stream.h b/src/lib/audio_decoder_stream.h
index 90269a0f4..265bbe004 100644
--- a/src/lib/audio_decoder_stream.h
+++ b/src/lib/audio_decoder_stream.h
@@ -29,11 +29,12 @@ class AudioContent;
 class AudioDecoder;
 class Resampler;
 class Log;
+class Decoder;
 
 class AudioDecoderStream
 {
 public:
-	AudioDecoderStream (boost::shared_ptr<const AudioContent>, AudioStreamPtr, AudioDecoder* decoder, boost::shared_ptr<Log> log);
+	AudioDecoderStream (boost::shared_ptr<const AudioContent>, AudioStreamPtr, Decoder* decoder, boost::shared_ptr<Log> log);
 
 	ContentAudio get (Frame time, Frame length, bool accurate);
 	void audio (boost::shared_ptr<const AudioBuffers>, ContentTime);
@@ -47,7 +48,7 @@ private:
 
 	boost::shared_ptr<const AudioContent> _content;
 	AudioStreamPtr _stream;
-	AudioDecoder* _decoder;
+	Decoder* _decoder;
 	boost::shared_ptr<Log> _log;
 	boost::shared_ptr<Resampler> _resampler;
 	boost::optional<Frame> _position;
diff --git a/src/lib/dcp_decoder.cc b/src/lib/dcp_decoder.cc
index 8008fe515..2a7691666 100644
--- a/src/lib/dcp_decoder.cc
+++ b/src/lib/dcp_decoder.cc
@@ -20,7 +20,10 @@
 #include "dcp_decoder.h"
 #include "dcp_content.h"
 #include "audio_content.h"
+#include "video_decoder.h"
+#include "audio_decoder.h"
 #include "j2k_image_proxy.h"
+#include "subtitle_decoder.h"
 #include "image.h"
 #include "config.h"
 #include <dcp/dcp.h>
@@ -44,11 +47,20 @@ using boost::shared_ptr;
 using boost::dynamic_pointer_cast;
 
 DCPDecoder::DCPDecoder (shared_ptr<const DCPContent> c, shared_ptr<Log> log, bool fast)
-	: VideoDecoder (c, log)
-	, AudioDecoder (c->audio, fast, log)
-	, SubtitleDecoder (c->subtitle)
-	, _dcp_content (c)
+	: _dcp_content (c)
 {
+	video.reset (new VideoDecoder (this, c, log));
+	audio.reset (new AudioDecoder (this, c->audio, fast, log));
+
+	subtitle.reset (
+		new SubtitleDecoder (
+			this,
+			c->subtitle,
+			bind (&DCPDecoder::image_subtitles_during, this, _1, _2),
+			bind (&DCPDecoder::text_subtitles_during, this, _1, _2)
+			)
+		);
+
 	dcp::DCP dcp (c->directory ());
 	dcp.read (false, 0, true);
 	if (c->kdm ()) {
@@ -85,14 +97,14 @@ DCPDecoder::pass (PassReason reason, bool)
 		shared_ptr<dcp::StereoPictureAsset> stereo = dynamic_pointer_cast<dcp::StereoPictureAsset> (asset);
 		int64_t const entry_point = (*_reel)->main_picture()->entry_point ();
 		if (mono) {
-			video (shared_ptr<ImageProxy> (new J2KImageProxy (mono->get_frame (entry_point + frame), asset->size())), offset + frame);
+			video->video (shared_ptr<ImageProxy> (new J2KImageProxy (mono->get_frame (entry_point + frame), asset->size())), offset + frame);
 		} else {
-			video (
+			video->video (
 				shared_ptr<ImageProxy> (new J2KImageProxy (stereo->get_frame (entry_point + frame), asset->size(), dcp::EYE_LEFT)),
 				offset + frame
 				);
 
-			video (
+			video->video (
 				shared_ptr<ImageProxy> (new J2KImageProxy (stereo->get_frame (entry_point + frame), asset->size(), dcp::EYE_RIGHT)),
 				offset + frame
 				);
@@ -114,7 +126,7 @@ DCPDecoder::pass (PassReason reason, bool)
 			}
 		}
 
-		audio (_dcp_content->audio->stream(), data, ContentTime::from_frames (offset, vfr) + _next);
+		audio->audio (_dcp_content->audio->stream(), data, ContentTime::from_frames (offset, vfr) + _next);
 	}
 
 	if ((*_reel)->main_subtitle ()) {
@@ -127,7 +139,7 @@ DCPDecoder::pass (PassReason reason, bool)
 
 		if (!subs.empty ()) {
 			/* XXX: assuming that all `subs' are at the same time; maybe this is ok */
-			text_subtitle (
+			subtitle->text_subtitle (
 				ContentTimePeriod (
 					ContentTime::from_frames (offset - entry_point, vfr) + ContentTime::from_seconds (subs.front().in().as_seconds ()),
 					ContentTime::from_frames (offset - entry_point, vfr) + ContentTime::from_seconds (subs.front().out().as_seconds ())
@@ -152,9 +164,9 @@ DCPDecoder::pass (PassReason reason, bool)
 void
 DCPDecoder::seek (ContentTime t, bool accurate)
 {
-	VideoDecoder::seek (t, accurate);
-	AudioDecoder::seek (t, accurate);
-	SubtitleDecoder::seek (t, accurate);
+	video->seek (t, accurate);
+	audio->seek (t, accurate);
+	subtitle->seek (t, accurate);
 
 	_reel = _reels.begin ();
 	while (_reel != _reels.end() && t >= ContentTime::from_frames ((*_reel)->main_picture()->duration(), _dcp_content->active_video_frame_rate ())) {
diff --git a/src/lib/dcp_decoder.h b/src/lib/dcp_decoder.h
index ce9a3ef9a..6e58c4904 100644
--- a/src/lib/dcp_decoder.h
+++ b/src/lib/dcp_decoder.h
@@ -21,18 +21,17 @@
  *  @brief A decoder of existing DCPs.
  */
 
-#include "video_decoder.h"
-#include "audio_decoder.h"
-#include "subtitle_decoder.h"
+#include "decoder.h"
 
 namespace dcp {
 	class Reel;
 }
 
 class DCPContent;
+class Log;
 struct dcp_subtitle_within_dcp_test;
 
-class DCPDecoder : public VideoDecoder, public AudioDecoder, public SubtitleDecoder
+class DCPDecoder : public Decoder
 {
 public:
 	DCPDecoder (boost::shared_ptr<const DCPContent>, boost::shared_ptr<Log> log, bool fast);
diff --git a/src/lib/dcp_subtitle_decoder.cc b/src/lib/dcp_subtitle_decoder.cc
index 964ee6f20..23f5dd529 100644
--- a/src/lib/dcp_subtitle_decoder.cc
+++ b/src/lib/dcp_subtitle_decoder.cc
@@ -1,5 +1,5 @@
 /*
-    Copyright (C) 2014 Carl Hetherington <cth@carlh.net>
+    Copyright (C) 2014-2016 Carl Hetherington <cth@carlh.net>
 
     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
@@ -25,10 +25,19 @@
 using std::list;
 using std::cout;
 using boost::shared_ptr;
+using boost::bind;
 
 DCPSubtitleDecoder::DCPSubtitleDecoder (shared_ptr<const DCPSubtitleContent> content)
-	: SubtitleDecoder (content->subtitle)
 {
+	subtitle.reset (
+		new SubtitleDecoder (
+			this,
+			content->subtitle,
+			bind (&DCPSubtitleDecoder::image_subtitles_during, this, _1, _2),
+			bind (&DCPSubtitleDecoder::text_subtitles_during, this, _1, _2)
+			)
+		);
+
 	shared_ptr<dcp::SubtitleAsset> c (load (content->path (0)));
 	_subtitles = c->subtitles ();
 	_next = _subtitles.begin ();
@@ -37,7 +46,7 @@ DCPSubtitleDecoder::DCPSubtitleDecoder (shared_ptr<const DCPSubtitleContent> con
 void
 DCPSubtitleDecoder::seek (ContentTime time, bool accurate)
 {
-	SubtitleDecoder::seek (time, accurate);
+	subtitle->seek (time, accurate);
 
 	_next = _subtitles.begin ();
 	list<dcp::SubtitleString>::const_iterator i = _subtitles.begin ();
@@ -68,7 +77,7 @@ DCPSubtitleDecoder::pass (PassReason, bool)
 		++_next;
 	}
 
-	text_subtitle (p, s);
+	subtitle->text_subtitle (p, s);
 
 	return false;
 }
diff --git a/src/lib/dcp_subtitle_decoder.h b/src/lib/dcp_subtitle_decoder.h
index 1f5377622..fcefc0201 100644
--- a/src/lib/dcp_subtitle_decoder.h
+++ b/src/lib/dcp_subtitle_decoder.h
@@ -22,7 +22,7 @@
 
 class DCPSubtitleContent;
 
-class DCPSubtitleDecoder : public SubtitleDecoder, public DCPSubtitle
+class DCPSubtitleDecoder : public DCPSubtitle, public Decoder
 {
 public:
 	DCPSubtitleDecoder (boost::shared_ptr<const DCPSubtitleContent>);
diff --git a/src/lib/decoder.h b/src/lib/decoder.h
index 10bb45310..979c6cf58 100644
--- a/src/lib/decoder.h
+++ b/src/lib/decoder.h
@@ -29,6 +29,9 @@
 #include <boost/utility.hpp>
 
 class Decoded;
+class VideoDecoder;
+class AudioDecoder;
+class SubtitleDecoder;
 
 /** @class Decoder.
  *  @brief Parent class for decoders of content.
@@ -38,8 +41,15 @@ class Decoder : public boost::noncopyable
 public:
 	virtual ~Decoder () {}
 
-protected:
-	friend class AudioDecoderStream;
+	boost::shared_ptr<VideoDecoder> video;
+	boost::shared_ptr<AudioDecoder> audio;
+	boost::shared_ptr<SubtitleDecoder> subtitle;
+
+	enum PassReason {
+		PASS_REASON_VIDEO,
+		PASS_REASON_AUDIO,
+		PASS_REASON_SUBTITLE
+	};
 
 	/** Seek so that the next pass() will yield the next thing
 	 *  (video/sound frame, subtitle etc.) at or after the requested
@@ -51,12 +61,6 @@ protected:
 	 */
 	virtual void seek (ContentTime time, bool accurate) = 0;
 
-	enum PassReason {
-		PASS_REASON_VIDEO,
-		PASS_REASON_AUDIO,
-		PASS_REASON_SUBTITLE
-	};
-
 	/** @return true if this decoder has already returned all its data and will give no more */
 	virtual bool pass (PassReason, bool accurate) = 0;
 };
diff --git a/src/lib/ffmpeg_decoder.cc b/src/lib/ffmpeg_decoder.cc
index d84bb2a52..2f123e484 100644
--- a/src/lib/ffmpeg_decoder.cc
+++ b/src/lib/ffmpeg_decoder.cc
@@ -27,14 +27,17 @@
 #include "util.h"
 #include "log.h"
 #include "ffmpeg_decoder.h"
+#include "subtitle_decoder.h"
 #include "ffmpeg_audio_stream.h"
 #include "ffmpeg_subtitle_stream.h"
 #include "video_filter_graph.h"
 #include "audio_buffers.h"
 #include "ffmpeg_content.h"
 #include "raw_image_proxy.h"
+#include "video_decoder.h"
 #include "film.h"
 #include "md5_digester.h"
+#include "audio_decoder.h"
 #include "compose.hpp"
 #include <dcp/subtitle_string.h>
 #include <sub/ssa_reader.h>
@@ -72,17 +75,30 @@ using boost::split;
 using dcp::Size;
 
 FFmpegDecoder::FFmpegDecoder (shared_ptr<const FFmpegContent> c, shared_ptr<Log> log, bool fast)
-	: VideoDecoder (c, log)
-	, AudioDecoder (c->audio, fast, log)
-	, SubtitleDecoder (c->subtitle)
-	, FFmpeg (c)
+	: FFmpeg (c)
 	, _log (log)
 {
 	if (c->video) {
+		video.reset (new VideoDecoder (this, c, log));
 		_pts_offset = pts_offset (c->ffmpeg_audio_streams(), c->first_video(), c->active_video_frame_rate());
 	} else {
 		_pts_offset = ContentTime ();
 	}
+
+	if (c->audio) {
+		audio.reset (new AudioDecoder (this, c->audio, fast, log));
+	}
+
+	if (c->subtitle) {
+		subtitle.reset (
+			new SubtitleDecoder (
+				this,
+				c->subtitle,
+				bind (&FFmpegDecoder::image_subtitles_during, this, _1, _2),
+				bind (&FFmpegDecoder::text_subtitles_during, this, _1, _2)
+				)
+			);
+	}
 }
 
 void
@@ -98,7 +114,7 @@ FFmpegDecoder::flush ()
 	while (decode_video_packet ()) {}
 
 	decode_audio_packet ();
-	AudioDecoder::flush ();
+	audio->flush ();
 }
 
 bool
@@ -125,7 +141,7 @@ FFmpegDecoder::pass (PassReason reason, bool accurate)
 	int const si = _packet.stream_index;
 	shared_ptr<const FFmpegContent> fc = _ffmpeg_content;
 
-	if (_video_stream && si == _video_stream.get() && !_ignore_video && (accurate || reason != PASS_REASON_SUBTITLE)) {
+	if (_video_stream && si == _video_stream.get() && !video->ignore_video() && (accurate || reason != PASS_REASON_SUBTITLE)) {
 		decode_video_packet ();
 	} else if (fc->subtitle_stream() && fc->subtitle_stream()->uses_index (_format_context, si)) {
 		decode_subtitle_packet ();
@@ -284,9 +300,9 @@ FFmpegDecoder::bytes_per_audio_sample (shared_ptr<FFmpegAudioStream> stream) con
 void
 FFmpegDecoder::seek (ContentTime time, bool accurate)
 {
-	VideoDecoder::seek (time, accurate);
-	AudioDecoder::seek (time, accurate);
-	SubtitleDecoder::seek (time, accurate);
+	video->seek (time, accurate);
+	audio->seek (time, accurate);
+	subtitle->seek (time, accurate);
 
 	/* If we are doing an `accurate' seek, we need to use pre-roll, as
 	   we don't really know what the seek will give us.
@@ -379,7 +395,7 @@ FFmpegDecoder::decode_audio_packet ()
 			}
 
 			if (data->frames() > 0) {
-				audio (*stream, data, ct);
+				audio->audio (*stream, data, ct);
 			}
 		}
 
@@ -424,7 +440,7 @@ FFmpegDecoder::decode_video_packet ()
 
 		if (i->second != AV_NOPTS_VALUE) {
 			double const pts = i->second * av_q2d (_format_context->streams[_video_stream.get()]->time_base) + _pts_offset.seconds ();
-			video (
+			video->video (
 				shared_ptr<ImageProxy> (new RawImageProxy (image)),
 				llrint (pts * _ffmpeg_content->active_video_frame_rate ())
 				);
@@ -568,7 +584,7 @@ FFmpegDecoder::decode_bitmap_subtitle (AVSubtitleRect const * rect, ContentTimeP
 		static_cast<double> (rect->h) / vs.height
 		);
 
-	image_subtitle (period, image, scaled_rect);
+	subtitle->image_subtitle (period, image, scaled_rect);
 }
 
 void
@@ -635,5 +651,5 @@ FFmpegDecoder::decode_ass_subtitle (string ass, ContentTimePeriod period)
 		}
 	}
 
-	text_subtitle (period, ss);
+	subtitle->text_subtitle (period, ss);
 }
diff --git a/src/lib/ffmpeg_decoder.h b/src/lib/ffmpeg_decoder.h
index 990d643a7..40ccb9793 100644
--- a/src/lib/ffmpeg_decoder.h
+++ b/src/lib/ffmpeg_decoder.h
@@ -1,5 +1,5 @@
 /*
-    Copyright (C) 2012-2014 Carl Hetherington <cth@carlh.net>
+    Copyright (C) 2012-2016 Carl Hetherington <cth@carlh.net>
 
     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
@@ -22,9 +22,7 @@
  */
 
 #include "util.h"
-#include "video_decoder.h"
-#include "audio_decoder.h"
-#include "subtitle_decoder.h"
+#include "decoder.h"
 #include "ffmpeg.h"
 extern "C" {
 #include <libavcodec/avcodec.h>
@@ -36,12 +34,13 @@ extern "C" {
 class Log;
 class VideoFilterGraph;
 class FFmpegAudioStream;
+class AudioBuffers;
 struct ffmpeg_pts_offset_test;
 
 /** @class FFmpegDecoder
  *  @brief A decoder using FFmpeg to decode content.
  */
-class FFmpegDecoder : public VideoDecoder, public AudioDecoder, public SubtitleDecoder, public FFmpeg
+class FFmpegDecoder : public FFmpeg, public Decoder
 {
 public:
 	FFmpegDecoder (boost::shared_ptr<const FFmpegContent>, boost::shared_ptr<Log>, bool fast);
diff --git a/src/lib/image_decoder.cc b/src/lib/image_decoder.cc
index 6c46b9c08..71157dd5d 100644
--- a/src/lib/image_decoder.cc
+++ b/src/lib/image_decoder.cc
@@ -1,5 +1,5 @@
 /*
-    Copyright (C) 2012-2013 Carl Hetherington <cth@carlh.net>
+    Copyright (C) 2012-2016 Carl Hetherington <cth@carlh.net>
 
     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
@@ -17,16 +17,18 @@
 
 */
 
-#include <iostream>
-#include <boost/filesystem.hpp>
-#include <Magick++.h>
 #include "image_content.h"
 #include "image_decoder.h"
+#include "video_decoder.h"
 #include "image.h"
 #include "magick_image_proxy.h"
 #include "j2k_image_proxy.h"
 #include "film.h"
 #include "exceptions.h"
+#include "video_content.h"
+#include <Magick++.h>
+#include <boost/filesystem.hpp>
+#include <iostream>
 
 #include "i18n.h"
 
@@ -35,11 +37,10 @@ using boost::shared_ptr;
 using dcp::Size;
 
 ImageDecoder::ImageDecoder (shared_ptr<const ImageContent> c, shared_ptr<Log> log)
-	: VideoDecoder (c, log)
-	, _image_content (c)
+	: _image_content (c)
 	, _video_position (0)
 {
-
+	video.reset (new VideoDecoder (this, c, log));
 }
 
 bool
@@ -62,7 +63,7 @@ ImageDecoder::pass (PassReason, bool)
 		}
 	}
 
-	video (_image, _video_position);
+	video->video (_image, _video_position);
 	++_video_position;
 	return false;
 }
@@ -70,6 +71,6 @@ ImageDecoder::pass (PassReason, bool)
 void
 ImageDecoder::seek (ContentTime time, bool accurate)
 {
-	VideoDecoder::seek (time, accurate);
+	video->seek (time, accurate);
 	_video_position = time.frames_round (_image_content->active_video_frame_rate ());
 }
diff --git a/src/lib/image_decoder.h b/src/lib/image_decoder.h
index 9d81cdac1..862baffee 100644
--- a/src/lib/image_decoder.h
+++ b/src/lib/image_decoder.h
@@ -17,11 +17,13 @@
 
 */
 
-#include "video_decoder.h"
+#include "decoder.h"
 
 class ImageContent;
+class Log;
+class ImageProxy;
 
-class ImageDecoder : public VideoDecoder
+class ImageDecoder : public Decoder
 {
 public:
 	ImageDecoder (boost::shared_ptr<const ImageContent> c, boost::shared_ptr<Log> log);
@@ -31,7 +33,7 @@ public:
 	}
 
 private:
-	bool pass (PassReason, bool);
+	bool pass (Decoder::PassReason, bool);
 	void seek (ContentTime, bool);
 
 	boost::shared_ptr<const ImageContent> _image_content;
diff --git a/src/lib/player.cc b/src/lib/player.cc
index 2abb6a30c..ba386e39a 100644
--- a/src/lib/player.cc
+++ b/src/lib/player.cc
@@ -20,6 +20,7 @@
 #include "player.h"
 #include "film.h"
 #include "ffmpeg_decoder.h"
+#include "video_decoder.h"
 #include "audio_buffers.h"
 #include "audio_content.h"
 #include "ffmpeg_content.h"
@@ -206,14 +207,12 @@ Player::setup_pieces ()
 			frc = FrameRateChange (dsc->active_video_frame_rate(), _film->video_frame_rate());
 		}
 
-		shared_ptr<VideoDecoder> vd = dynamic_pointer_cast<VideoDecoder> (decoder);
-		if (vd && _ignore_video) {
-			vd->set_ignore_video ();
+		if (decoder->video && _ignore_video) {
+			decoder->video->set_ignore_video ();
 		}
 
-		shared_ptr<AudioDecoder> ad = dynamic_pointer_cast<AudioDecoder> (decoder);
-		if (ad && _ignore_audio) {
-			ad->set_ignore_audio ();
+		if (decoder->audio && _ignore_audio) {
+			decoder->audio->set_ignore_audio ();
 		}
 
 		_pieces.push_back (shared_ptr<Piece> (new Piece (i, decoder, frc.get ())));
diff --git a/src/lib/sndfile_decoder.cc b/src/lib/sndfile_decoder.cc
index b05750ac8..7762ab1e4 100644
--- a/src/lib/sndfile_decoder.cc
+++ b/src/lib/sndfile_decoder.cc
@@ -35,12 +35,11 @@ using boost::shared_ptr;
 
 SndfileDecoder::SndfileDecoder (shared_ptr<const SndfileContent> c, bool fast, shared_ptr<Log> log)
 	: Sndfile (c)
-	, AudioDecoder (c->audio, fast, log)
 	, _done (0)
 	, _remaining (_info.frames)
 	, _deinterleave_buffer (0)
 {
-
+	audio.reset (new AudioDecoder (this, c->audio, fast, log));
 }
 
 SndfileDecoder::~SndfileDecoder ()
@@ -87,7 +86,7 @@ SndfileDecoder::pass (PassReason, bool)
 	}
 
 	data->set_frames (this_time);
-	audio (_sndfile_content->audio->stream (), data, ContentTime::from_frames (_done, _info.samplerate));
+	audio->audio (_sndfile_content->audio->stream (), data, ContentTime::from_frames (_done, _info.samplerate));
 	_done += this_time;
 	_remaining -= this_time;
 
@@ -97,7 +96,7 @@ SndfileDecoder::pass (PassReason, bool)
 void
 SndfileDecoder::seek (ContentTime t, bool accurate)
 {
-	AudioDecoder::seek (t, accurate);
+	audio->seek (t, accurate);
 
 	_done = t.frames_round (_info.samplerate);
 	_remaining = _info.frames - _done;
diff --git a/src/lib/sndfile_decoder.h b/src/lib/sndfile_decoder.h
index 6f3a6cc48..d3f9342b3 100644
--- a/src/lib/sndfile_decoder.h
+++ b/src/lib/sndfile_decoder.h
@@ -22,7 +22,7 @@
 
 class SndfileContent;
 
-class SndfileDecoder : public Sndfile, public AudioDecoder
+class SndfileDecoder : public Sndfile, public Decoder
 {
 public:
 	SndfileDecoder (boost::shared_ptr<const SndfileContent> c, bool fast, boost::shared_ptr<Log> log);
diff --git a/src/lib/subtitle_decoder.cc b/src/lib/subtitle_decoder.cc
index 454243b52..e9692b99f 100644
--- a/src/lib/subtitle_decoder.cc
+++ b/src/lib/subtitle_decoder.cc
@@ -1,5 +1,5 @@
 /*
-    Copyright (C) 2013-2015 Carl Hetherington <cth@carlh.net>
+    Copyright (C) 2013-2016 Carl Hetherington <cth@carlh.net>
 
     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
@@ -27,9 +27,18 @@ using std::list;
 using std::cout;
 using boost::shared_ptr;
 using boost::optional;
-
-SubtitleDecoder::SubtitleDecoder (shared_ptr<const SubtitleContent> c)
-	: _subtitle_content (c)
+using boost::function;
+
+SubtitleDecoder::SubtitleDecoder (
+	Decoder* parent,
+	shared_ptr<const SubtitleContent> c,
+	function<list<ContentTimePeriod> (ContentTimePeriod, bool)> image_subtitles_during,
+	function<list<ContentTimePeriod> (ContentTimePeriod, bool)> text_subtitles_during
+	)
+	: _parent (parent)
+	, _subtitle_content (c)
+	, _image_subtitles_during (image_subtitles_during)
+	, _text_subtitles_during (text_subtitles_during)
 {
 
 }
@@ -72,7 +81,7 @@ SubtitleDecoder::get (list<T> const & subs, list<ContentTimePeriod> const & sp,
 	 *  (a) give us what we want, or
 	 *  (b) hit the end of the decoder.
 	 */
-	while (!pass(PASS_REASON_SUBTITLE, accurate) && (subs.empty() || (subs.back().period().to < sp.back().to))) {}
+	while (!_parent->pass(Decoder::PASS_REASON_SUBTITLE, accurate) && (subs.empty() || (subs.back().period().to < sp.back().to))) {}
 
 	/* Now look for what we wanted in the data we have collected */
 	/* XXX: inefficient */
@@ -107,13 +116,13 @@ SubtitleDecoder::get (list<T> const & subs, list<ContentTimePeriod> const & sp,
 list<ContentTextSubtitle>
 SubtitleDecoder::get_text_subtitles (ContentTimePeriod period, bool starting, bool accurate)
 {
-	return get<ContentTextSubtitle> (_decoded_text_subtitles, text_subtitles_during (period, starting), period, starting, accurate);
+	return get<ContentTextSubtitle> (_decoded_text_subtitles, _text_subtitles_during (period, starting), period, starting, accurate);
 }
 
 list<ContentImageSubtitle>
 SubtitleDecoder::get_image_subtitles (ContentTimePeriod period, bool starting, bool accurate)
 {
-	return get<ContentImageSubtitle> (_decoded_image_subtitles, image_subtitles_during (period, starting), period, starting, accurate);
+	return get<ContentImageSubtitle> (_decoded_image_subtitles, _image_subtitles_during (period, starting), period, starting, accurate);
 }
 
 void
diff --git a/src/lib/subtitle_decoder.h b/src/lib/subtitle_decoder.h
index ef62d8b88..317755107 100644
--- a/src/lib/subtitle_decoder.h
+++ b/src/lib/subtitle_decoder.h
@@ -1,5 +1,5 @@
 /*
-    Copyright (C) 2013 Carl Hetherington <cth@carlh.net>
+    Copyright (C) 2013-2016 Carl Hetherington <cth@carlh.net>
 
     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
@@ -28,33 +28,43 @@
 
 class Image;
 
-class SubtitleDecoder : public virtual Decoder
+class SubtitleDecoder
 {
 public:
-	SubtitleDecoder (boost::shared_ptr<const SubtitleContent>);
+	/** Second parameter to the _during functions is true if we
+	 *  want only subtitles that start during the period,
+	 *  otherwise we want subtitles that overlap the period.
+	 */
+	SubtitleDecoder (
+		Decoder* parent,
+		boost::shared_ptr<const SubtitleContent>,
+		boost::function<std::list<ContentTimePeriod> (ContentTimePeriod, bool)> image_subtitles_during,
+		boost::function<std::list<ContentTimePeriod> (ContentTimePeriod, bool)> text_subtitles_during
+		);
 
 	std::list<ContentImageSubtitle> get_image_subtitles (ContentTimePeriod period, bool starting, bool accurate);
 	std::list<ContentTextSubtitle> get_text_subtitles (ContentTimePeriod period, bool starting, bool accurate);
 
-protected:
 	void seek (ContentTime, bool);
 
 	void image_subtitle (ContentTimePeriod period, boost::shared_ptr<Image>, dcpomatic::Rect<double>);
 	void text_subtitle (ContentTimePeriod period, std::list<dcp::SubtitleString>);
 
+	boost::shared_ptr<const SubtitleContent> content () const {
+		return _subtitle_content;
+	}
+
+private:
+	Decoder* _parent;
 	std::list<ContentImageSubtitle> _decoded_image_subtitles;
 	std::list<ContentTextSubtitle> _decoded_text_subtitles;
 	boost::shared_ptr<const SubtitleContent> _subtitle_content;
 
-private:
 	template <class T>
 	std::list<T> get (std::list<T> const & subs, std::list<ContentTimePeriod> const & sp, ContentTimePeriod period, bool starting, bool accurate);
 
-	/** @param starting true if we want only subtitles that start during the period, otherwise
-	 *  we want subtitles that overlap the period.
-	 */
-	virtual std::list<ContentTimePeriod> image_subtitles_during (ContentTimePeriod period, bool starting) const = 0;
-	virtual std::list<ContentTimePeriod> text_subtitles_during (ContentTimePeriod period, bool starting) const = 0;
+	boost::function<std::list<ContentTimePeriod> (ContentTimePeriod, bool)> _image_subtitles_during;
+	boost::function<std::list<ContentTimePeriod> (ContentTimePeriod, bool)> _text_subtitles_during;
 };
 
 #endif
diff --git a/src/lib/text_subtitle_decoder.cc b/src/lib/text_subtitle_decoder.cc
index 94604cd71..f76bb7f75 100644
--- a/src/lib/text_subtitle_decoder.cc
+++ b/src/lib/text_subtitle_decoder.cc
@@ -34,17 +34,23 @@ using boost::optional;
 using boost::dynamic_pointer_cast;
 
 TextSubtitleDecoder::TextSubtitleDecoder (shared_ptr<const TextSubtitleContent> content)
-	: SubtitleDecoder (content->subtitle)
-	, TextSubtitle (content)
+	: TextSubtitle (content)
 	, _next (0)
 {
-
+	subtitle.reset (
+		new SubtitleDecoder (
+			this,
+			content->subtitle,
+			bind (&TextSubtitleDecoder::image_subtitles_during, this, _1, _2),
+			bind (&TextSubtitleDecoder::text_subtitles_during, this, _1, _2)
+			)
+		);
 }
 
 void
 TextSubtitleDecoder::seek (ContentTime time, bool accurate)
 {
-	SubtitleDecoder::seek (time, accurate);
+	subtitle->seek (time, accurate);
 
 	_next = 0;
 	while (_next < _subtitles.size() && ContentTime::from_seconds (_subtitles[_next].from.all_as_seconds ()) < time) {
@@ -79,7 +85,7 @@ TextSubtitleDecoder::pass (PassReason, bool)
 					j.italic,
 					j.bold,
 					/* force the colour to whatever is configured */
-					_subtitle_content->colour(),
+					subtitle->content()->colour(),
 					j.font_size.points (72 * 11),
 					1.0,
 					dcp::Time (_subtitles[_next].from.all_as_seconds(), 1000),
@@ -93,8 +99,8 @@ TextSubtitleDecoder::pass (PassReason, bool)
 					dcp::VALIGN_TOP,
 					dcp::DIRECTION_LTR,
 					j.text,
-					_subtitle_content->outline() ? dcp::BORDER : dcp::NONE,
-					_subtitle_content->outline_colour(),
+					subtitle->content()->outline() ? dcp::BORDER : dcp::NONE,
+					subtitle->content()->outline_colour(),
 					dcp::Time (0, 1000),
 					dcp::Time (0, 1000)
 					)
@@ -102,7 +108,7 @@ TextSubtitleDecoder::pass (PassReason, bool)
 		}
 	}
 
-	text_subtitle (content_time_period (_subtitles[_next]), out);
+	subtitle->text_subtitle (content_time_period (_subtitles[_next]), out);
 
 	++_next;
 	return false;
diff --git a/src/lib/text_subtitle_decoder.h b/src/lib/text_subtitle_decoder.h
index 67d2caca8..9e37ecc3b 100644
--- a/src/lib/text_subtitle_decoder.h
+++ b/src/lib/text_subtitle_decoder.h
@@ -25,7 +25,7 @@
 
 class TextSubtitleContent;
 
-class TextSubtitleDecoder : public SubtitleDecoder, public TextSubtitle
+class TextSubtitleDecoder : public Decoder, public TextSubtitle
 {
 public:
 	TextSubtitleDecoder (boost::shared_ptr<const TextSubtitleContent>);
diff --git a/src/lib/video_decoder.cc b/src/lib/video_decoder.cc
index 8862eaa6e..fce5b367a 100644
--- a/src/lib/video_decoder.cc
+++ b/src/lib/video_decoder.cc
@@ -34,12 +34,14 @@ using std::back_inserter;
 using boost::shared_ptr;
 using boost::optional;
 
-VideoDecoder::VideoDecoder (shared_ptr<const Content> c, shared_ptr<Log> log)
+VideoDecoder::VideoDecoder (Decoder* parent, shared_ptr<const Content> c, shared_ptr<Log> log)
 #ifdef DCPOMATIC_DEBUG
 	: test_gaps (0)
-	, _video_content (c)
+	, _parent (parent),
+	  _video_content (c)
 #else
-	: _video_content (c)
+        : _parent (parent)
+	, _video_content (c)
 #endif
 	, _log (log)
 	, _last_seek_accurate (true)
@@ -105,7 +107,7 @@ VideoDecoder::get_video (Frame frame, bool accurate)
 				break;
 			}
 
-			if (pass (PASS_REASON_VIDEO, accurate)) {
+			if (_parent->pass (Decoder::PASS_REASON_VIDEO, accurate)) {
 				/* The decoder has nothing more for us */
 				no_data = true;
 				break;
@@ -128,7 +130,7 @@ VideoDecoder::get_video (Frame frame, bool accurate)
 
 	} else {
 		/* Any frame will do: use the first one that comes out of pass() */
-		while (_decoded_video.empty() && !pass (PASS_REASON_VIDEO, accurate)) {}
+		while (_decoded_video.empty() && !_parent->pass (Decoder::PASS_REASON_VIDEO, accurate)) {}
 		if (!_decoded_video.empty ()) {
 			dec.push_back (_decoded_video.front ());
 		}
diff --git a/src/lib/video_decoder.h b/src/lib/video_decoder.h
index 669a5ef1e..c14a877f2 100644
--- a/src/lib/video_decoder.h
+++ b/src/lib/video_decoder.h
@@ -39,20 +39,22 @@ class Log;
 /** @class VideoDecoder
  *  @brief Parent for classes which decode video.
  */
-class VideoDecoder : public virtual Decoder
+class VideoDecoder
 {
 public:
-	VideoDecoder (boost::shared_ptr<const Content> c, boost::shared_ptr<Log> log);
+	VideoDecoder (Decoder* parent, boost::shared_ptr<const Content> c, boost::shared_ptr<Log> log);
 
 	std::list<ContentVideo> get_video (Frame frame, bool accurate);
 
 	void set_ignore_video ();
+	bool ignore_video () const {
+		return _ignore_video;
+	}
 
 #ifdef DCPOMATIC_DEBUG
 	int test_gaps;
 #endif
 
-protected:
 	friend struct video_decoder_fill_test1;
 	friend struct video_decoder_fill_test2;
 	friend struct ffmpeg_pts_offset_test;
@@ -60,10 +62,14 @@ protected:
 
 	void seek (ContentTime time, bool accurate);
 	void video (boost::shared_ptr<const ImageProxy>, Frame frame);
+
+private:
+
 	std::list<ContentVideo> decoded_video (Frame frame);
 	void fill_one_eye (Frame from, Frame to, Eyes);
 	void fill_both_eyes (Frame from, Frame to, Eyes);
 
+	Decoder* _parent;
 	boost::shared_ptr<const Content> _video_content;
 	boost::shared_ptr<Log> _log;
 	std::list<ContentVideo> _decoded_video;
diff --git a/src/wx/subtitle_panel.cc b/src/wx/subtitle_panel.cc
index 3a0063c95..1d6325dfd 100644
--- a/src/wx/subtitle_panel.cc
+++ b/src/wx/subtitle_panel.cc
@@ -377,7 +377,7 @@ SubtitlePanel::subtitle_view_clicked ()
 	ContentList c = _parent->selected_subtitle ();
 	DCPOMATIC_ASSERT (c.size() == 1);
 
-	shared_ptr<SubtitleDecoder> decoder;
+	shared_ptr<Decoder> decoder;
 
 	shared_ptr<TextSubtitleContent> sr = dynamic_pointer_cast<TextSubtitleContent> (c.front ());
 	if (sr) {
diff --git a/src/wx/subtitle_view.cc b/src/wx/subtitle_view.cc
index 916f1eedc..a33a401df 100644
--- a/src/wx/subtitle_view.cc
+++ b/src/wx/subtitle_view.cc
@@ -28,7 +28,7 @@ using std::list;
 using boost::shared_ptr;
 using boost::dynamic_pointer_cast;
 
-SubtitleView::SubtitleView (wxWindow* parent, shared_ptr<Film> film, shared_ptr<SubtitleDecoder> decoder, DCPTime position)
+SubtitleView::SubtitleView (wxWindow* parent, shared_ptr<Film> film, shared_ptr<Decoder> decoder, DCPTime position)
 	: wxDialog (parent, wxID_ANY, _("Subtitles"), wxDefaultPosition, wxDefaultSize, wxDEFAULT_DIALOG_STYLE | wxRESIZE_BORDER)
 {
 	_list = new wxListCtrl (this, wxID_ANY, wxDefaultPosition, wxDefaultSize, wxLC_REPORT | wxLC_SINGLE_SEL);
@@ -65,7 +65,7 @@ SubtitleView::SubtitleView (wxWindow* parent, shared_ptr<Film> film, shared_ptr<
 		sizer->Add (buttons, wxSizerFlags().Expand().DoubleBorder());
 	}
 
-	list<ContentTextSubtitle> subs = decoder->get_text_subtitles (ContentTimePeriod (ContentTime(), ContentTime::max ()), true, true);
+	list<ContentTextSubtitle> subs = decoder->subtitle->get_text_subtitles (ContentTimePeriod (ContentTime(), ContentTime::max ()), true, true);
 	FrameRateChange const frc = film->active_frame_rate_change (position);
 	int n = 0;
 	for (list<ContentTextSubtitle>::const_iterator i = subs.begin(); i != subs.end(); ++i) {
diff --git a/src/wx/subtitle_view.h b/src/wx/subtitle_view.h
index f5a61890b..d95f26668 100644
--- a/src/wx/subtitle_view.h
+++ b/src/wx/subtitle_view.h
@@ -1,5 +1,5 @@
 /*
-    Copyright (C) 2014 Carl Hetherington <cth@carlh.net>
+    Copyright (C) 2014-2016 Carl Hetherington <cth@carlh.net>
 
     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
@@ -21,12 +21,12 @@
 #include <wx/wx.h>
 #include <wx/listctrl.h>
 
-class SubtitleDecoder;
+class Decoder;
 
 class SubtitleView : public wxDialog
 {
 public:
-	SubtitleView (wxWindow *, boost::shared_ptr<Film>, boost::shared_ptr<SubtitleDecoder>, DCPTime position);
+	SubtitleView (wxWindow *, boost::shared_ptr<Film>, boost::shared_ptr<Decoder>, DCPTime position);
 
 private:
 	wxListCtrl* _list;