Don't trust video timestamps from FFmpegDecoder.

Back-ported from 98342fb53eae4d32440fc69c279f2ca0fef785b5 in v2.15.x.

7 files changed, 49 insertions, 13 deletions

diff --git a/src/lib/audio_decoder.cc b/src/lib/audio_decoder.cc
index 440510ce5..2ab527f59 100644
--- a/src/lib/audio_decoder.cc
+++ b/src/lib/audio_decoder.cc
@@ -110,7 +110,7 @@ AudioDecoder::stream_position (shared_ptr<const Film> film, AudioStreamPtr strea
 	return ContentTime::from_frames (i->second, _content->resampled_frame_rate(film));
 }
 
-ContentTime
+optional<ContentTime>
 AudioDecoder::position (shared_ptr<const Film> film) const
 {
 	optional<ContentTime> p;
@@ -121,7 +121,7 @@ AudioDecoder::position (shared_ptr<const Film> film) const
 		}
 	}
 
-	return p.get_value_or(ContentTime());
+	return p;
 }
 
 void
diff --git a/src/lib/audio_decoder.h b/src/lib/audio_decoder.h
index 50e361e8f..002d839e9 100644
--- a/src/lib/audio_decoder.h
+++ b/src/lib/audio_decoder.h
@@ -47,7 +47,7 @@ class AudioDecoder : public boost::enable_shared_from_this<AudioDecoder>, public
 public:
 	AudioDecoder (Decoder* parent, boost::shared_ptr<const AudioContent> content, bool fast);
 
-	ContentTime position (boost::shared_ptr<const Film> film) const;
+	boost::optional<ContentTime> position (boost::shared_ptr<const Film> film) const;
 	void emit (boost::shared_ptr<const Film> film, AudioStreamPtr stream, boost::shared_ptr<const AudioBuffers>, ContentTime);
 	void seek ();
 	void flush ();
diff --git a/src/lib/decoder_part.h b/src/lib/decoder_part.h
index 7ba2cb2eb..e763b7313 100644
--- a/src/lib/decoder_part.h
+++ b/src/lib/decoder_part.h
@@ -34,7 +34,7 @@ public:
 	DecoderPart (Decoder* parent);
 	virtual ~DecoderPart () {}
 
-	virtual ContentTime position (boost::shared_ptr<const Film> film) const = 0;
+	virtual boost::optional<ContentTime> position (boost::shared_ptr<const Film> film) const = 0;
 	virtual void seek () = 0;
 
 	void set_ignore (bool i) {
diff --git a/src/lib/ffmpeg_decoder.cc b/src/lib/ffmpeg_decoder.cc
index 0f39f7727..fd248c39a 100644
--- a/src/lib/ffmpeg_decoder.cc
+++ b/src/lib/ffmpeg_decoder.cc
@@ -126,7 +126,7 @@ FFmpegDecoder::flush ()
 	if (video) {
 		double const vfr = _ffmpeg_content->video_frame_rate().get();
 		Frame const f = full_length.frames_round (vfr);
-		Frame v = video->position(film()).frames_round(vfr) + 1;
+		Frame v = video->position(film()).get_value_or(ContentTime()).frames_round(vfr) + 1;
 		while (v < f) {
 			video->emit (film(), shared_ptr<const ImageProxy> (new RawImageProxy (_black_image)), v);
 			++v;
diff --git a/src/lib/text_decoder.h b/src/lib/text_decoder.h
index a82f43f51..a320e146b 100644
--- a/src/lib/text_decoder.h
+++ b/src/lib/text_decoder.h
@@ -44,7 +44,7 @@ public:
 		ContentTime first
 		);
 
-	ContentTime position (boost::shared_ptr<const Film>) const {
+	boost::optional<ContentTime> position (boost::shared_ptr<const Film>) const {
 		return _position;
 	}
 
diff --git a/src/lib/video_decoder.cc b/src/lib/video_decoder.cc
index de1df727f..46611bbed 100644
--- a/src/lib/video_decoder.cc
+++ b/src/lib/video_decoder.cc
@@ -53,12 +53,44 @@ VideoDecoder::VideoDecoder (Decoder* parent, shared_ptr<const Content> c)
  *  and so on.
  */
 void
-VideoDecoder::emit (shared_ptr<const Film> film, shared_ptr<const ImageProxy> image, Frame frame)
+VideoDecoder::emit (shared_ptr<const Film> film, shared_ptr<const ImageProxy> image, Frame decoder_frame)
 {
 	if (ignore ()) {
 		return;
 	}
 
+	double const afr = _content->active_video_frame_rate(film);
+
+	Frame frame;
+	if (!_position) {
+		/* This is the first data we have received since initialisation or seek.  Set
+		   the position based on the frame that was given.  After this first time
+		   we just cound frames, since (as with audio) it seems that ContentTimes
+		   are unreliable from FFmpegDecoder.  They are much better than audio times
+		   but still we get the occasional one which is duplicated.  In this case
+		   ffmpeg seems to carry on regardless, processing the video frame as normal.
+		   If we drop the frame with the duplicated timestamp we obviously lose sync.
+		*/
+		_position = ContentTime::from_frames (decoder_frame, afr);
+		if (_content->video->frame_type() == VIDEO_FRAME_TYPE_3D_ALTERNATE) {
+			frame = decoder_frame / 2;
+			_last_emitted_eyes = EYES_RIGHT;
+		} else {
+			frame = decoder_frame;
+		}
+	} else {
+		if (_content->video->frame_type() == VIDEO_FRAME_TYPE_3D_ALTERNATE) {
+			DCPOMATIC_ASSERT (_last_emitted_eyes);
+			if (_last_emitted_eyes.get() == EYES_RIGHT) {
+				frame = _position->frames_round(afr) + 1;
+			} else {
+				frame = _position->frames_round(afr);
+			}
+		} else {
+			frame = _position->frames_round(afr) + 1;
+		}
+	}
+
 	switch (_content->video->frame_type ()) {
 	case VIDEO_FRAME_TYPE_2D:
 		Data (ContentVideo (image, frame, EYES_BOTH, PART_WHOLE));
@@ -90,9 +122,13 @@ VideoDecoder::emit (shared_ptr<const Film> film, shared_ptr<const ImageProxy> im
 		break;
 	}
 	case VIDEO_FRAME_TYPE_3D_ALTERNATE:
-		Data (ContentVideo (image, frame / 2, (frame % 2) ? EYES_RIGHT : EYES_LEFT, PART_WHOLE));
-		frame /= 2;
+	{
+		DCPOMATIC_ASSERT (_last_emitted_eyes);
+		Eyes const eyes = _last_emitted_eyes.get() == EYES_LEFT ? EYES_RIGHT : EYES_LEFT;
+		Data (ContentVideo (image, frame, eyes, PART_WHOLE));
+		_last_emitted_eyes = eyes;
 		break;
+	}
 	case VIDEO_FRAME_TYPE_3D_LEFT_RIGHT:
 		Data (ContentVideo (image, frame, EYES_LEFT, PART_LEFT_HALF));
 		Data (ContentVideo (image, frame, EYES_RIGHT, PART_RIGHT_HALF));
@@ -111,7 +147,7 @@ VideoDecoder::emit (shared_ptr<const Film> film, shared_ptr<const ImageProxy> im
 		DCPOMATIC_ASSERT (false);
 	}
 
-	_position = ContentTime::from_frames (frame, _content->active_video_frame_rate(film));
+	_position = ContentTime::from_frames (frame, afr);
 }
 
 void
diff --git a/src/lib/video_decoder.h b/src/lib/video_decoder.h
index ed56feea0..98a8e7b7a 100644
--- a/src/lib/video_decoder.h
+++ b/src/lib/video_decoder.h
@@ -51,7 +51,7 @@ public:
 	friend struct ffmpeg_pts_offset_test;
 	friend void ffmpeg_decoder_sequential_test_one (boost::filesystem::path file, float fps, int gaps, int video_length);
 
-	ContentTime position (boost::shared_ptr<const Film>) const {
+	boost::optional<ContentTime> position (boost::shared_ptr<const Film>) const {
 		return _position;
 	}
 
@@ -63,10 +63,10 @@ public:
 
 private:
 	boost::shared_ptr<const Content> _content;
-	/** Frame of last thing to be emitted */
+	/** Frame of last thing to be emitted; only used for 3D */
 	boost::optional<Frame> _last_emitted_frame;
 	boost::optional<Eyes> _last_emitted_eyes;
-	ContentTime _position;
+	boost::optional<ContentTime> _position;
 };
 
 #endif