+
+ if (_frame_interval_checker->guess() != FrameIntervalChecker::AGAIN) {
+ _frame_interval_checker.reset ();
+ }
+ }
+
+ Frame frame;
+ Eyes eyes = Eyes::BOTH;
+ 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 count 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.
+ */
+
+ if (vft == VideoFrameType::THREE_D_ALTERNATE) {
+ frame = decoder_frame / 2;
+ eyes = (decoder_frame % 2) ? Eyes::RIGHT : Eyes::LEFT;
+ } else {
+ frame = decoder_frame;
+ if (vft == VideoFrameType::THREE_D) {
+ auto j2k = dynamic_pointer_cast<const J2KImageProxy>(image);
+ /* At the moment only DCP decoders producers VideoFrameType::THREE_D, so only the J2KImageProxy
+ * knows which eye it is.
+ */
+ if (j2k && j2k->eye()) {
+ eyes = j2k->eye().get() == dcp::Eye::LEFT ? Eyes::LEFT : Eyes::RIGHT;
+ }
+ }
+ }
+
+ _position = ContentTime::from_frames (frame, afr);
+ } else {
+ if (vft == VideoFrameType::THREE_D) {
+ auto j2k = dynamic_pointer_cast<const J2KImageProxy>(image);
+ if (j2k && j2k->eye()) {
+ if (j2k->eye() == dcp::Eye::LEFT) {
+ frame = _position->frames_round(afr) + 1;
+ eyes = Eyes::LEFT;
+ } else {
+ frame = _position->frames_round(afr);
+ eyes = Eyes::RIGHT;
+ }
+ } else {
+ /* This should not happen; see above */
+ frame = _position->frames_round(afr) + 1;
+ }
+ } else if (vft == VideoFrameType::THREE_D_ALTERNATE) {
+ DCPOMATIC_ASSERT (_last_emitted_eyes);
+ if (_last_emitted_eyes.get() == Eyes::RIGHT) {
+ frame = _position->frames_round(afr) + 1;
+ eyes = Eyes::LEFT;
+ } else {
+ frame = _position->frames_round(afr);
+ eyes = Eyes::RIGHT;
+ }
+ } else {
+ frame = _position->frames_round(afr) + 1;
+ }
+ }
+
+ switch (vft) {
+ case VideoFrameType::TWO_D:
+ case VideoFrameType::THREE_D:
+ Data (ContentVideo (image, frame, eyes, Part::WHOLE));
+ break;
+ case VideoFrameType::THREE_D_ALTERNATE:
+ {
+ Data (ContentVideo (image, frame, eyes, Part::WHOLE));