From a0eff2446835a2a29d751a4810fe182c486a2eb6 Mon Sep 17 00:00:00 2001
From: Carl Hetherington <cth@carlh.net>
Date: Tue, 20 Feb 2018 23:34:59 +0000
Subject: Add a 2-frame `delay' on content arriving at the player to give
 subtitle content the chance to catch up.  Fixes problems observed when
 overlaying a DCP subtitle onto an existing DCP and then seeking into the
 first subtitle.  After the seek the decoder positions were:

DCP: 0.
subtitle: first subtitle time.

This causes the DCP decoder to be pass()ed first and so the subtitle
for the video frame has not arrived yet.

I hope this does not cause unpredicted side effects...
---
 src/lib/player.cc | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

(limited to 'src/lib/player.cc')

diff --git a/src/lib/player.cc b/src/lib/player.cc
index 71b04e7b2..a8a72a229 100644
--- a/src/lib/player.cc
+++ b/src/lib/player.cc
@@ -49,6 +49,7 @@
 #include "image_decoder.h"
 #include "compose.hpp"
 #include "shuffler.h"
+#include "delay.h"
 #include <dcp/reel.h>
 #include <dcp/reel_sound_asset.h>
 #include <dcp/reel_subtitle_asset.h>
@@ -89,6 +90,7 @@ Player::Player (shared_ptr<const Film> film, shared_ptr<const Playlist> playlist
 	, _play_referenced (false)
 	, _audio_merger (_film->audio_frame_rate())
 	, _shuffler (0)
+	, _delay (0)
 {
 	_film_changed_connection = _film->Changed.connect (bind (&Player::film_changed, this, _1));
 	_playlist_changed_connection = _playlist->Changed.connect (bind (&Player::playlist_changed, this));
@@ -103,6 +105,7 @@ Player::Player (shared_ptr<const Film> film, shared_ptr<const Playlist> playlist
 Player::~Player ()
 {
 	delete _shuffler;
+	delete _delay;
 }
 
 void
@@ -114,6 +117,10 @@ Player::setup_pieces ()
 	_shuffler = new Shuffler();
 	_shuffler->Video.connect(bind(&Player::video, this, _1, _2));
 
+	delete _delay;
+	_delay = new Delay();
+	_delay->Video.connect(bind(&Player::video, this, _1, _2));
+
 	BOOST_FOREACH (shared_ptr<Content> i, _playlist->content ()) {
 
 		if (!i->paths_valid ()) {
@@ -149,9 +156,13 @@ Player::setup_pieces ()
 
 		if (decoder->video) {
 			if (i->video->frame_type() == VIDEO_FRAME_TYPE_3D_LEFT || i->video->frame_type() == VIDEO_FRAME_TYPE_3D_RIGHT) {
+				/* We need a Shuffler to cope with 3D L/R video data arriving out of sequence */
 				decoder->video->Data.connect (bind (&Shuffler::video, _shuffler, weak_ptr<Piece>(piece), _1));
 			} else {
-				decoder->video->Data.connect (bind (&Player::video, this, weak_ptr<Piece>(piece), _1));
+				/* We need a Delay to give a little wiggle room to ensure that relevent subtitles arrive at the
+				   player before the video that requires them.
+				*/
+				decoder->video->Data.connect (bind (&Delay::video, _delay, weak_ptr<Piece>(piece), _1));
 			}
 		}
 
@@ -649,6 +660,7 @@ Player::pass ()
 
 	if (done) {
 		_shuffler->flush ();
+		_delay->flush ();
 	}
 	return done;
 }
@@ -931,6 +943,10 @@ Player::seek (DCPTime time, bool accurate)
 		_shuffler->clear ();
 	}
 
+	if (_delay) {
+		_delay->clear ();
+	}
+
 	if (_audio_processor) {
 		_audio_processor->flush ();
 	}
-- 
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