X-Git-Url: https://main.carlh.net/gitweb/?a=blobdiff_plain;f=src%2Flib%2Fffmpeg_decoder.cc;h=25ca9bb8882f658385ac677f86a36c685ba5b404;hb=db468a15e50c8491d4b8462ad0676be905f49065;hp=023b6d540fe02134c328fc006fe5b0df535a1dd5;hpb=e3636952b0d443f61c2966450cc68bc25480dfe2;p=dcpomatic.git

diff --git a/src/lib/ffmpeg_decoder.cc b/src/lib/ffmpeg_decoder.cc
index 023b6d540..25ca9bb88 100644
--- a/src/lib/ffmpeg_decoder.cc
+++ b/src/lib/ffmpeg_decoder.cc
@@ -41,26 +41,33 @@ extern "C" {
 #include "transcoder.h"
 #include "job.h"
 #include "filter.h"
-#include "options.h"
 #include "exceptions.h"
 #include "image.h"
 #include "util.h"
 #include "log.h"
 #include "ffmpeg_decoder.h"
+#include "filter_graph.h"
 #include "subtitle.h"
 
+#include "i18n.h"
+
 using std::cout;
 using std::string;
 using std::vector;
 using std::stringstream;
+using std::list;
 using boost::shared_ptr;
-
-FFmpegDecoder::FFmpegDecoder (shared_ptr<Film> f, shared_ptr<const Options> o, Job* j, bool minimal, bool ignore_length)
-	: Decoder (f, o, j, minimal, ignore_length)
+using boost::optional;
+using boost::dynamic_pointer_cast;
+using libdcp::Size;
+
+FFmpegDecoder::FFmpegDecoder (shared_ptr<const Film> f, shared_ptr<const FFmpegContent> c, bool video, bool audio, bool subtitles, bool video_sync)
+	: Decoder (f)
+	, VideoDecoder (f)
+	, AudioDecoder (f)
+	, _ffmpeg_content (c)
 	, _format_context (0)
 	, _video_stream (-1)
-	, _audio_stream (-1)
-	, _subtitle_stream (-1)
 	, _frame (0)
 	, _video_codec_context (0)
 	, _video_codec (0)
@@ -68,11 +75,19 @@ FFmpegDecoder::FFmpegDecoder (shared_ptr<Film> f, shared_ptr<const Options> o, J
 	, _audio_codec (0)
 	, _subtitle_codec_context (0)
 	, _subtitle_codec (0)
+	, _decode_video (video)
+	, _decode_audio (audio)
+	, _decode_subtitles (subtitles)
+	, _video_sync (video_sync)
 {
 	setup_general ();
 	setup_video ();
 	setup_audio ();
 	setup_subtitle ();
+
+	if (!video_sync) {
+		_first_video = 0;
+	}
 }
 
 FFmpegDecoder::~FFmpegDecoder ()
@@ -88,24 +103,23 @@ FFmpegDecoder::~FFmpegDecoder ()
 	if (_subtitle_codec_context) {
 		avcodec_close (_subtitle_codec_context);
 	}
-	
+
 	av_free (_frame);
+	
 	avformat_close_input (&_format_context);
 }	
 
 void
 FFmpegDecoder::setup_general ()
 {
-	int r;
-	
 	av_register_all ();
 
-	if ((r = avformat_open_input (&_format_context, _film->content_path().c_str(), 0, 0)) != 0) {
-		throw OpenFileError (_film->content_path ());
+	if (avformat_open_input (&_format_context, _ffmpeg_content->file().string().c_str(), 0, 0) < 0) {
+		throw OpenFileError (_ffmpeg_content->file().string ());
 	}
 
 	if (avformat_find_stream_info (_format_context, 0) < 0) {
-		throw DecodeError ("could not find stream information");
+		throw DecodeError (_("could not find stream information"));
 	}
 
 	/* Find video, audio and subtitle streams and choose the first of each */
@@ -115,35 +129,31 @@ FFmpegDecoder::setup_general ()
 		if (s->codec->codec_type == AVMEDIA_TYPE_VIDEO) {
 			_video_stream = i;
 		} else if (s->codec->codec_type == AVMEDIA_TYPE_AUDIO) {
-			if (_audio_stream == -1) {
-				_audio_stream = i;
+
+			/* This is a hack; sometimes it seems that _audio_codec_context->channel_layout isn't set up,
+			   so bodge it here.  No idea why we should have to do this.
+			*/
+
+			if (s->codec->channel_layout == 0) {
+				s->codec->channel_layout = av_get_default_channel_layout (s->codec->channels);
 			}
-			_audio_streams.push_back (AudioStream (stream_name (s), i, s->codec->channels));
+			
+			_audio_streams.push_back (
+				FFmpegAudioStream (stream_name (s), i, s->codec->sample_rate, s->codec->channel_layout)
+				);
+			
 		} else if (s->codec->codec_type == AVMEDIA_TYPE_SUBTITLE) {
-			if (_subtitle_stream == -1) {
-				_subtitle_stream = i;
-			}
-			_subtitle_streams.push_back (SubtitleStream (stream_name (s), i));
+			_subtitle_streams.push_back (FFmpegSubtitleStream (stream_name (s), i));
 		}
 	}
 
-	/* Now override audio and subtitle streams with those from the Film, if it has any */
-
-	if (_film->audio_stream_index() != -1) {
-		_audio_stream = _film->audio_stream().id();
-	}
-
-	if (_film->subtitle_stream_index() != -1) {
-		_subtitle_stream = _film->subtitle_stream().id ();
-	}
-
 	if (_video_stream < 0) {
-		throw DecodeError ("could not find video stream");
+		throw DecodeError (N_("could not find video stream"));
 	}
 
 	_frame = avcodec_alloc_frame ();
 	if (_frame == 0) {
-		throw DecodeError ("could not allocate frame");
+		throw DecodeError (N_("could not allocate frame"));
 	}
 }
 
@@ -154,76 +164,64 @@ FFmpegDecoder::setup_video ()
 	_video_codec = avcodec_find_decoder (_video_codec_context->codec_id);
 
 	if (_video_codec == 0) {
-		throw DecodeError ("could not find video decoder");
+		throw DecodeError (_("could not find video decoder"));
 	}
 
-	/* I think this prevents problems with green hash on decodes and
-	   "changing frame properties on the fly is not supported by all filters"
-	   messages with some content.  Although I'm not sure; needs checking.
-	*/
-	AVDictionary* opts = 0;
-	av_dict_set (&opts, "threads", "1", 0);
-	
-	if (avcodec_open2 (_video_codec_context, _video_codec, &opts) < 0) {
-		throw DecodeError ("could not open video decoder");
+	if (avcodec_open2 (_video_codec_context, _video_codec, 0) < 0) {
+		throw DecodeError (N_("could not open video decoder"));
 	}
 }
 
 void
 FFmpegDecoder::setup_audio ()
 {
-	if (_audio_stream < 0) {
+	if (!_ffmpeg_content->audio_stream ()) {
 		return;
 	}
-	
-	_audio_codec_context = _format_context->streams[_audio_stream]->codec;
+
+	_audio_codec_context = _format_context->streams[_ffmpeg_content->audio_stream()->id]->codec;
 	_audio_codec = avcodec_find_decoder (_audio_codec_context->codec_id);
 
 	if (_audio_codec == 0) {
-		throw DecodeError ("could not find audio decoder");
+		throw DecodeError (_("could not find audio decoder"));
 	}
 
 	if (avcodec_open2 (_audio_codec_context, _audio_codec, 0) < 0) {
-		throw DecodeError ("could not open audio decoder");
-	}
-
-	/* This is a hack; sometimes it seems that _audio_codec_context->channel_layout isn't set up,
-	   so bodge it here.  No idea why we should have to do this.
-	*/
-
-	if (_audio_codec_context->channel_layout == 0) {
-		_audio_codec_context->channel_layout = av_get_default_channel_layout (audio_channels ());
+		throw DecodeError (N_("could not open audio decoder"));
 	}
 }
 
 void
 FFmpegDecoder::setup_subtitle ()
 {
-	if (_subtitle_stream < 0) {
+	if (!_ffmpeg_content->subtitle_stream() || _ffmpeg_content->subtitle_stream()->id >= int (_format_context->nb_streams)) {
 		return;
 	}
 
-	_subtitle_codec_context = _format_context->streams[_subtitle_stream]->codec;
+	_subtitle_codec_context = _format_context->streams[_ffmpeg_content->subtitle_stream()->id]->codec;
 	_subtitle_codec = avcodec_find_decoder (_subtitle_codec_context->codec_id);
 
 	if (_subtitle_codec == 0) {
-		throw DecodeError ("could not find subtitle decoder");
+		throw DecodeError (_("could not find subtitle decoder"));
 	}
 	
 	if (avcodec_open2 (_subtitle_codec_context, _subtitle_codec, 0) < 0) {
-		throw DecodeError ("could not open subtitle decoder");
+		throw DecodeError (N_("could not open subtitle decoder"));
 	}
 }
 
 
 bool
-FFmpegDecoder::do_pass ()
+FFmpegDecoder::pass ()
 {
 	int r = av_read_frame (_format_context, &_packet);
 	
 	if (r < 0) {
 		if (r != AVERROR_EOF) {
-			throw DecodeError ("error on av_read_frame");
+			/* Maybe we should fail here, but for now we'll just finish off instead */
+			char buf[256];
+			av_strerror (r, buf, sizeof(buf));
+			_film->log()->log (String::compose (N_("error on av_read_frame (%1) (%2)"), buf, r));
 		}
 		
 		/* Get any remaining frames */
@@ -235,108 +233,41 @@ FFmpegDecoder::do_pass ()
 
 		int frame_finished;
 
-		while (avcodec_decode_video2 (_video_codec_context, _frame, &frame_finished, &_packet) >= 0 && frame_finished) {
-			process_video (_frame);
+		if (_decode_video) {
+			while (avcodec_decode_video2 (_video_codec_context, _frame, &frame_finished, &_packet) >= 0 && frame_finished) {
+				filter_and_emit_video (_frame);
+			}
 		}
 
-		if (_audio_stream >= 0 && _opt->decode_audio) {
-			while (avcodec_decode_audio4 (_audio_codec_context, _frame, &frame_finished, &_packet) >= 0 && frame_finished) {
-				int const data_size = av_samples_get_buffer_size (
-					0, _audio_codec_context->channels, _frame->nb_samples, audio_sample_format (), 1
-					);
-
-				assert (_audio_codec_context->channels == _film->audio_channels());
-				process_audio (_frame->data[0], data_size);
-			}
+		if (_ffmpeg_content->audio_stream() && _decode_audio) {
+			decode_audio_packet ();
 		}
 
 		return true;
 	}
 
-	double const pts_seconds = av_q2d (_format_context->streams[_packet.stream_index]->time_base) * _packet.pts;
-
 	avcodec_get_frame_defaults (_frame);
-	
-	if (_packet.stream_index == _video_stream) {
 
-		if (!_first_video) {
-			_first_video = pts_seconds;
-		}
+	if (_packet.stream_index == _video_stream && _decode_video) {
 
 		int frame_finished;
-		if (avcodec_decode_video2 (_video_codec_context, _frame, &frame_finished, &_packet) >= 0 && frame_finished) {
-
-			/* Where we are in the output, in seconds */
-			double const out_pts_seconds = video_frame() / frames_per_second();
+		int const r = avcodec_decode_video2 (_video_codec_context, _frame, &frame_finished, &_packet);
+		if (r >= 0 && frame_finished) {
 
-			/* Difference between where we are and where we should be */
-			double const delta = pts_seconds - out_pts_seconds;
-			double const one_frame = 1 / frames_per_second();
-
-			/* Insert frames if required to get out_pts_seconds up to pts_seconds */
-			if (delta > one_frame) {
-				int const extra = rint (delta / one_frame);
-				for (int i = 0; i < extra; ++i) {
-					_film->log()->log (String::compose ("Extra frame inserted at %1s", out_pts_seconds));
-					process_video (_frame);
-				}
+			if (r != _packet.size) {
+				_film->log()->log (String::compose (N_("Used only %1 bytes of %2 in packet"), r, _packet.size));
 			}
 
-			if (delta > -one_frame) {
-				/* Process this frame */
-				process_video (_frame);
+			if (_video_sync) {
+				out_with_sync ();
 			} else {
-				/* Otherwise we are omitting a frame to keep things right */
-				_film->log()->log (String::compose ("Frame removed at %1s", out_pts_seconds));
+				filter_and_emit_video (_frame);
 			}
 		}
 
-	} else if (_audio_stream >= 0 && _packet.stream_index == _audio_stream && _opt->decode_audio && _first_video && _first_video.get() <= pts_seconds) {
-
-		/* Note: We only decode audio if we've had our first video packet through, and if it
-		   was before this packet.  Until then audio is thrown away.
-		*/
-		
-		if (!_first_audio) {
-			_first_audio = pts_seconds;
-			
-			/* This is our first audio packet, and if we've arrived here we must have had our
-			   first video packet.  Push some silence to make up the gap between our first
-			   video packet and our first audio.
-			*/
-			
-			/* frames of silence that we must push */
-			int const s = rint ((_first_audio.get() - _first_video.get()) * audio_sample_rate ());
-			
-			_film->log()->log (
-				String::compose (
-					"First video at %1, first audio at %2, pushing %3 frames of silence for %4 channels (%5 bytes per sample)",
-					_first_video.get(), _first_audio.get(), s, audio_channels(), bytes_per_audio_sample()
-					)
-				);
-			
-			/* hence bytes */
-			int const b = s * audio_channels() * bytes_per_audio_sample();
-			
-			/* XXX: this assumes that it won't be too much, and there are shaky assumptions
-			   that all sound representations are silent with memset()ed zero data.
-			*/
-			uint8_t silence[b];
-			memset (silence, 0, b);
-			process_audio (silence, b);
-		}
-		
-		int frame_finished;
-		if (avcodec_decode_audio4 (_audio_codec_context, _frame, &frame_finished, &_packet) >= 0 && frame_finished) {
-			int const data_size = av_samples_get_buffer_size (
-				0, _audio_codec_context->channels, _frame->nb_samples, audio_sample_format (), 1
-				);
-			
-			assert (_audio_codec_context->channels == _film->audio_channels());
-			process_audio (_frame->data[0], data_size);
-		}
-			
-	} else if (_subtitle_stream >= 0 && _packet.stream_index == _subtitle_stream && _opt->decode_subtitles && _first_video) {
+	} else if (_ffmpeg_content->audio_stream() && _packet.stream_index == _ffmpeg_content->audio_stream()->id && _decode_audio) {
+		decode_audio_packet ();
+	} else if (_ffmpeg_content->subtitle_stream() && _packet.stream_index == _ffmpeg_content->subtitle_stream()->id && _decode_subtitles && _first_video) {
 
 		int got_subtitle;
 		AVSubtitle sub;
@@ -345,9 +276,14 @@ FFmpegDecoder::do_pass ()
 			   indicate that the previous subtitle should stop.
 			*/
 			if (sub.num_rects > 0) {
-				process_subtitle (shared_ptr<TimedSubtitle> (new TimedSubtitle (sub, _first_video.get())));
+				shared_ptr<TimedSubtitle> ts;
+				try {
+					emit_subtitle (shared_ptr<TimedSubtitle> (new TimedSubtitle (sub)));
+				} catch (...) {
+					/* some problem with the subtitle; we probably didn't understand it */
+				}
 			} else {
-				process_subtitle (shared_ptr<TimedSubtitle> ());
+				emit_subtitle (shared_ptr<TimedSubtitle> ());
 			}
 			avsubtitle_free (&sub);
 		}
@@ -357,6 +293,102 @@ FFmpegDecoder::do_pass ()
 	return false;
 }
 
+/** @param data pointer to array of pointers to buffers.
+ *  Only the first buffer will be used for non-planar data, otherwise there will be one per channel.
+ */
+shared_ptr<AudioBuffers>
+FFmpegDecoder::deinterleave_audio (uint8_t** data, int size)
+{
+	assert (_ffmpeg_content->audio_channels());
+	assert (bytes_per_audio_sample());
+
+	/* Deinterleave and convert to float */
+
+	assert ((size % (bytes_per_audio_sample() * _ffmpeg_content->audio_channels())) == 0);
+
+	int const total_samples = size / bytes_per_audio_sample();
+	int const frames = total_samples / _ffmpeg_content->audio_channels();
+	shared_ptr<AudioBuffers> audio (new AudioBuffers (_ffmpeg_content->audio_channels(), frames));
+
+	switch (audio_sample_format()) {
+	case AV_SAMPLE_FMT_S16:
+	{
+		int16_t* p = reinterpret_cast<int16_t *> (data[0]);
+		int sample = 0;
+		int channel = 0;
+		for (int i = 0; i < total_samples; ++i) {
+			audio->data(channel)[sample] = float(*p++) / (1 << 15);
+
+			++channel;
+			if (channel == _ffmpeg_content->audio_channels()) {
+				channel = 0;
+				++sample;
+			}
+		}
+	}
+	break;
+
+	case AV_SAMPLE_FMT_S16P:
+	{
+		int16_t** p = reinterpret_cast<int16_t **> (data);
+		for (int i = 0; i < _ffmpeg_content->audio_channels(); ++i) {
+			for (int j = 0; j < frames; ++j) {
+				audio->data(i)[j] = static_cast<float>(p[i][j]) / (1 << 15);
+			}
+		}
+	}
+	break;
+	
+	case AV_SAMPLE_FMT_S32:
+	{
+		int32_t* p = reinterpret_cast<int32_t *> (data[0]);
+		int sample = 0;
+		int channel = 0;
+		for (int i = 0; i < total_samples; ++i) {
+			audio->data(channel)[sample] = static_cast<float>(*p++) / (1 << 31);
+
+			++channel;
+			if (channel == _ffmpeg_content->audio_channels()) {
+				channel = 0;
+				++sample;
+			}
+		}
+	}
+	break;
+
+	case AV_SAMPLE_FMT_FLT:
+	{
+		float* p = reinterpret_cast<float*> (data[0]);
+		int sample = 0;
+		int channel = 0;
+		for (int i = 0; i < total_samples; ++i) {
+			audio->data(channel)[sample] = *p++;
+
+			++channel;
+			if (channel == _ffmpeg_content->audio_channels()) {
+				channel = 0;
+				++sample;
+			}
+		}
+	}
+	break;
+		
+	case AV_SAMPLE_FMT_FLTP:
+	{
+		float** p = reinterpret_cast<float**> (data);
+		for (int i = 0; i < _ffmpeg_content->audio_channels(); ++i) {
+			memcpy (audio->data(i), p[i], frames * sizeof(float));
+		}
+	}
+	break;
+
+	default:
+		throw DecodeError (String::compose (_("Unrecognised audio sample format (%1)"), static_cast<int> (audio_sample_format())));
+	}
+
+	return audio;
+}
+
 float
 FFmpegDecoder::frames_per_second () const
 {
@@ -369,26 +401,6 @@ FFmpegDecoder::frames_per_second () const
 	return av_q2d (s->r_frame_rate);
 }
 
-int
-FFmpegDecoder::audio_channels () const
-{
-	if (_audio_codec_context == 0) {
-		return 0;
-	}
-
-	return _audio_codec_context->channels;
-}
-
-int
-FFmpegDecoder::audio_sample_rate () const
-{
-	if (_audio_codec_context == 0) {
-		return 0;
-	}
-	
-	return _audio_codec_context->sample_rate;
-}
-
 AVSampleFormat
 FFmpegDecoder::audio_sample_format () const
 {
@@ -399,20 +411,10 @@ FFmpegDecoder::audio_sample_format () const
 	return _audio_codec_context->sample_fmt;
 }
 
-int64_t
-FFmpegDecoder::audio_channel_layout () const
-{
-	if (_audio_codec_context == 0) {
-		return 0;
-	}
-	
-	return _audio_codec_context->channel_layout;
-}
-
-Size
+libdcp::Size
 FFmpegDecoder::native_size () const
 {
-	return Size (_video_codec_context->width, _video_codec_context->height);
+	return libdcp::Size (_video_codec_context->width, _video_codec_context->height);
 }
 
 PixelFormat
@@ -445,46 +447,234 @@ FFmpegDecoder::sample_aspect_ratio_denominator () const
 	return _video_codec_context->sample_aspect_ratio.den;
 }
 
-bool
-FFmpegDecoder::has_subtitles () const
-{
-	return (_subtitle_stream != -1);
-}
-
-vector<AudioStream>
-FFmpegDecoder::audio_streams () const
-{
-	return _audio_streams;
-}
-
-vector<SubtitleStream>
-FFmpegDecoder::subtitle_streams () const
-{
-	return _subtitle_streams;
-}
-
 string
 FFmpegDecoder::stream_name (AVStream* s) const
 {
 	stringstream n;
 	
-	AVDictionaryEntry const * lang = av_dict_get (s->metadata, "language", 0, 0);
+	AVDictionaryEntry const * lang = av_dict_get (s->metadata, N_("language"), 0, 0);
 	if (lang) {
 		n << lang->value;
 	}
 	
-	AVDictionaryEntry const * title = av_dict_get (s->metadata, "title", 0, 0);
+	AVDictionaryEntry const * title = av_dict_get (s->metadata, N_("title"), 0, 0);
 	if (title) {
 		if (!n.str().empty()) {
-			n << " ";
+			n << N_(" ");
 		}
 		n << title->value;
 	}
 
 	if (n.str().empty()) {
-		n << "unknown";
+		n << N_("unknown");
 	}
 
 	return n.str ();
 }
 
+int
+FFmpegDecoder::bytes_per_audio_sample () const
+{
+	return av_get_bytes_per_sample (audio_sample_format ());
+}
+
+void
+FFmpegDecoder::filter_and_emit_video (AVFrame* frame)
+{
+	boost::mutex::scoped_lock lm (_filter_graphs_mutex);
+	
+	shared_ptr<FilterGraph> graph;
+
+	list<shared_ptr<FilterGraph> >::iterator i = _filter_graphs.begin();
+	while (i != _filter_graphs.end() && !(*i)->can_process (libdcp::Size (frame->width, frame->height), (AVPixelFormat) frame->format)) {
+		++i;
+	}
+
+	if (i == _filter_graphs.end ()) {
+		graph.reset (new FilterGraph (_film, this, libdcp::Size (frame->width, frame->height), (AVPixelFormat) frame->format));
+		_filter_graphs.push_back (graph);
+		_film->log()->log (String::compose (N_("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, frame_time ());
+	}
+}
+
+bool
+FFmpegDecoder::seek (double p)
+{
+	return do_seek (p, false);
+}
+
+bool
+FFmpegDecoder::seek_to_last ()
+{
+	/* This AVSEEK_FLAG_BACKWARD in do_seek is a bit of a hack; without it, if we ask for a seek to the same place as last time
+	   (used when we change decoder parameters and want to re-fetch the frame) we end up going forwards rather than
+	   staying in the same place.
+	*/
+	return do_seek (last_source_time(), true);
+}
+
+bool
+FFmpegDecoder::do_seek (double p, bool backwards)
+{
+	int64_t const vt = p / av_q2d (_format_context->streams[_video_stream]->time_base);
+
+	int const r = av_seek_frame (_format_context, _video_stream, vt, backwards ? AVSEEK_FLAG_BACKWARD : 0);
+	
+	avcodec_flush_buffers (_video_codec_context);
+	if (_subtitle_codec_context) {
+		avcodec_flush_buffers (_subtitle_codec_context);
+	}
+	
+	return r < 0;
+}
+
+void
+FFmpegDecoder::out_with_sync ()
+{
+	/* Where we are in the output, in seconds */
+	double const out_pts_seconds = video_frame() / frames_per_second();
+	
+	/* Where we are in the source, in seconds */
+	double const source_pts_seconds = av_q2d (_format_context->streams[_packet.stream_index]->time_base)
+		* av_frame_get_best_effort_timestamp(_frame);
+	
+	_film->log()->log (
+		String::compose (N_("Source video frame ready; source at %1, output at %2"), source_pts_seconds, out_pts_seconds),
+		Log::VERBOSE
+		);
+	
+	if (!_first_video) {
+		_first_video = source_pts_seconds;
+	}
+	
+	/* Difference between where we are and where we should be */
+	double const delta = source_pts_seconds - _first_video.get() - out_pts_seconds;
+	double const one_frame = 1 / frames_per_second();
+	
+	/* Insert frames if required to get out_pts_seconds up to pts_seconds */
+	if (delta > one_frame) {
+		int const extra = rint (delta / one_frame);
+		for (int i = 0; i < extra; ++i) {
+			repeat_last_video ();
+			_film->log()->log (
+				String::compose (
+					N_("Extra video frame inserted at %1s; source frame %2, source PTS %3 (at %4 fps)"),
+					out_pts_seconds, video_frame(), source_pts_seconds, frames_per_second()
+					)
+				);
+		}
+	}
+	
+	if (delta > -one_frame) {
+		/* Process this frame */
+		filter_and_emit_video (_frame);
+	} else {
+		/* Otherwise we are omitting a frame to keep things right */
+		_film->log()->log (String::compose (N_("Frame removed at %1s"), out_pts_seconds));
+	}
+}
+
+void
+FFmpegDecoder::film_changed (Film::Property p)
+{
+	switch (p) {
+	case Film::CROP:
+	case Film::FILTERS:
+	{
+		boost::mutex::scoped_lock lm (_filter_graphs_mutex);
+		_filter_graphs.clear ();
+	}
+	OutputChanged ();
+	break;
+
+	default:
+		break;
+	}
+}
+
+/** @return Length (in video frames) according to our content's header */
+ContentVideoFrame
+FFmpegDecoder::video_length () const
+{
+	return (double(_format_context->duration) / AV_TIME_BASE) * frames_per_second();
+}
+
+double
+FFmpegDecoder::frame_time () const
+{
+	return av_frame_get_best_effort_timestamp(_frame) * av_q2d (_format_context->streams[_video_stream]->time_base);
+}
+
+void
+FFmpegDecoder::decode_audio_packet ()
+{
+	/* Audio packets can contain multiple frames, so we may have to call avcodec_decode_audio4
+	   several times.
+	*/
+	
+	AVPacket copy_packet = _packet;
+
+	while (copy_packet.size > 0) {
+
+		int frame_finished;
+		int const decode_result = avcodec_decode_audio4 (_audio_codec_context, _frame, &frame_finished, &copy_packet);
+		if (decode_result >= 0 && frame_finished) {
+			
+			/* Where we are in the source, in seconds */
+			double const source_pts_seconds = av_q2d (_format_context->streams[copy_packet.stream_index]->time_base)
+				* av_frame_get_best_effort_timestamp(_frame);
+			
+			/* We only decode audio if we've had our first video packet through, and if it
+			   was before this packet.  Until then audio is thrown away.
+			*/
+			
+			if ((_first_video && _first_video.get() <= source_pts_seconds) || !_decode_video) {
+				
+				if (!_first_audio && _decode_video) {
+					_first_audio = source_pts_seconds;
+					
+					/* This is our first audio frame, and if we've arrived here we must have had our
+					   first video frame.  Push some silence to make up any gap between our first
+					   video frame and our first audio.
+					*/
+					
+					/* frames of silence that we must push */
+					int const s = rint ((_first_audio.get() - _first_video.get()) * _ffmpeg_content->audio_frame_rate ());
+					
+					_film->log()->log (
+						String::compose (
+							N_("First video at %1, first audio at %2, pushing %3 audio frames of silence for %4 channels (%5 bytes per sample)"),
+							_first_video.get(), _first_audio.get(), s, _ffmpeg_content->audio_channels(), bytes_per_audio_sample()
+							)
+						);
+					
+					if (s) {
+						shared_ptr<AudioBuffers> audio (new AudioBuffers (_ffmpeg_content->audio_channels(), s));
+						audio->make_silent ();
+						Audio (audio);
+					}
+				}
+				
+				int const data_size = av_samples_get_buffer_size (
+					0, _audio_codec_context->channels, _frame->nb_samples, audio_sample_format (), 1
+					);
+				
+				assert (_audio_codec_context->channels == _ffmpeg_content->audio_channels());
+				Audio (deinterleave_audio (_frame->data, data_size));
+			}
+		}
+
+		if (decode_result >= 0) {
+			copy_packet.data += decode_result;
+			copy_packet.size -= decode_result;
+		}
+	}
+}