Optimise decoder_factory for DCPDecoder by offering the old decoder

(if available) to recover the list of reels from, rather than having
to scan the filesystem again.

6 files changed, 57 insertions, 25 deletions

diff --git a/src/lib/dcp_decoder.cc b/src/lib/dcp_decoder.cc
index 5a72fb228..b6947211c 100644
--- a/src/lib/dcp_decoder.cc
+++ b/src/lib/dcp_decoder.cc
@@ -56,7 +56,7 @@ using boost::dynamic_pointer_cast;
 using boost::optional;
 using namespace dcpomatic;
 
-DCPDecoder::DCPDecoder (shared_ptr<const Film> film, shared_ptr<const DCPContent> c, bool fast)
+DCPDecoder::DCPDecoder (shared_ptr<const Film> film, shared_ptr<const DCPContent> c, bool fast, shared_ptr<DCPDecoder> old)
 	: DCP (c)
 	, Decoder (film)
 	, _decode_referenced (false)
@@ -74,30 +74,35 @@ DCPDecoder::DCPDecoder (shared_ptr<const Film> film, shared_ptr<const DCPContent
 		}
 	}
 
-	list<shared_ptr<dcp::CPL> > cpl_list = cpls ();
+	if (old) {
+		_reels = old->_reels;
+	} else {
 
-	if (cpl_list.empty()) {
-		throw DCPError (_("No CPLs found in DCP."));
-	}
+		list<shared_ptr<dcp::CPL> > cpl_list = cpls ();
 
-	shared_ptr<dcp::CPL> cpl;
-	BOOST_FOREACH (shared_ptr<dcp::CPL> i, cpl_list) {
-		if (_dcp_content->cpl() && i->id() == _dcp_content->cpl().get()) {
-			cpl = i;
+		if (cpl_list.empty()) {
+			throw DCPError (_("No CPLs found in DCP."));
+		}
+
+		shared_ptr<dcp::CPL> cpl;
+		BOOST_FOREACH (shared_ptr<dcp::CPL> i, cpl_list) {
+			if (_dcp_content->cpl() && i->id() == _dcp_content->cpl().get()) {
+				cpl = i;
+			}
 		}
-	}
 
-	if (!cpl) {
-		/* No CPL found; probably an old file that doesn't specify it;
-		   just use the first one.
-		*/
-		cpl = cpls().front ();
+		if (!cpl) {
+			/* No CPL found; probably an old file that doesn't specify it;
+			   just use the first one.
+			*/
+			cpl = cpls().front ();
+		}
+
+		_reels = cpl->reels ();
 	}
 
 	set_decode_referenced (false);
 
-	_reels = cpl->reels ();
-
 	_reel = _reels.begin ();
 	_offset = 0;
 	get_readers ();
diff --git a/src/lib/dcp_decoder.h b/src/lib/dcp_decoder.h
index 0fc598bd7..f31d28053 100644
--- a/src/lib/dcp_decoder.h
+++ b/src/lib/dcp_decoder.h
@@ -40,7 +40,12 @@ struct dcp_subtitle_within_dcp_test;
 class DCPDecoder : public DCP, public Decoder
 {
 public:
-	DCPDecoder (boost::shared_ptr<const Film> film, boost::shared_ptr<const DCPContent>, bool fast);
+	DCPDecoder (
+		boost::shared_ptr<const Film> film,
+		boost::shared_ptr<const DCPContent>,
+		bool fast,
+		boost::shared_ptr<DCPDecoder> old = boost::shared_ptr<DCPDecoder>()
+		);
 
 	std::list<boost::shared_ptr<dcp::Reel> > reels () const {
 		return _reels;
diff --git a/src/lib/decoder_factory.cc b/src/lib/decoder_factory.cc
index 4b2a594e1..5d758956d 100644
--- a/src/lib/decoder_factory.cc
+++ b/src/lib/decoder_factory.cc
@@ -1,5 +1,5 @@
 /*
-    Copyright (C) 2016 Carl Hetherington <cth@carlh.net>
+    Copyright (C) 2016-2019 Carl Hetherington <cth@carlh.net>
 
     This file is part of DCP-o-matic.
 
@@ -30,14 +30,26 @@
 #include "dcp_subtitle_decoder.h"
 #include "video_mxf_content.h"
 #include "video_mxf_decoder.h"
+#include "timer.h"
 #include <boost/foreach.hpp>
 
 using std::list;
 using boost::shared_ptr;
 using boost::dynamic_pointer_cast;
 
+template <class T>
+shared_ptr<T>
+maybe_cast (shared_ptr<Decoder> d)
+{
+	if (!d) {
+		return shared_ptr<T> ();
+	}
+	return dynamic_pointer_cast<T> (d);
+}
+
+/** @param old_decoder A `used' decoder that has been previously made for this piece of content, or 0 */
 shared_ptr<Decoder>
-decoder_factory (shared_ptr<const Film> film, shared_ptr<const Content> content, bool fast)
+decoder_factory (shared_ptr<const Film> film, shared_ptr<const Content> content, bool fast, shared_ptr<Decoder> old_decoder)
 {
 	shared_ptr<const FFmpegContent> fc = dynamic_pointer_cast<const FFmpegContent> (content);
 	if (fc) {
@@ -47,7 +59,7 @@ decoder_factory (shared_ptr<const Film> film, shared_ptr<const Content> content,
 	shared_ptr<const DCPContent> dc = dynamic_pointer_cast<const DCPContent> (content);
 	if (dc) {
 		try {
-			return shared_ptr<Decoder> (new DCPDecoder(film, dc, fast));
+			return shared_ptr<Decoder> (new DCPDecoder(film, dc, fast, maybe_cast<DCPDecoder>(old_decoder)));
 		} catch (KDMError& e) {
 			/* This will be found and reported to the user when the content is examined */
 			return shared_ptr<Decoder>();
diff --git a/src/lib/decoder_factory.h b/src/lib/decoder_factory.h
index d4e39da17..cb145c8a9 100644
--- a/src/lib/decoder_factory.h
+++ b/src/lib/decoder_factory.h
@@ -1,5 +1,5 @@
 /*
-    Copyright (C) 2016 Carl Hetherington <cth@carlh.net>
+    Copyright (C) 2016-2019 Carl Hetherington <cth@carlh.net>
 
     This file is part of DCP-o-matic.
 
@@ -23,5 +23,6 @@ class ImageDecoder;
 extern boost::shared_ptr<Decoder> decoder_factory (
 	boost::shared_ptr<const Film> film,
 	boost::shared_ptr<const Content> content,
-	bool fast
+	bool fast,
+	boost::shared_ptr<Decoder> old_decoder
 	);
diff --git a/src/lib/player.cc b/src/lib/player.cc
index 08e138fe6..acde910be 100644
--- a/src/lib/player.cc
+++ b/src/lib/player.cc
@@ -138,6 +138,7 @@ have_audio (shared_ptr<Piece> piece)
 void
 Player::setup_pieces_unlocked ()
 {
+	list<shared_ptr<Piece> > old_pieces = _pieces;
 	_pieces.clear ();
 
 	delete _shuffler;
@@ -155,7 +156,15 @@ Player::setup_pieces_unlocked ()
 			continue;
 		}
 
-		shared_ptr<Decoder> decoder = decoder_factory (_film, i, _fast);
+		shared_ptr<Decoder> old_decoder;
+		BOOST_FOREACH (shared_ptr<Piece> j, old_pieces) {
+			if (j->content == i) {
+				old_decoder = j->decoder;
+				break;
+			}
+		}
+
+		shared_ptr<Decoder> decoder = decoder_factory (_film, i, _fast, old_decoder);
 		FrameRateChange frc (_film, i);
 
 		if (!decoder) {
diff --git a/src/wx/text_panel.cc b/src/wx/text_panel.cc
index 7c48831fc..98398aaa6 100644
--- a/src/wx/text_panel.cc
+++ b/src/wx/text_panel.cc
@@ -667,7 +667,7 @@ TextPanel::text_view_clicked ()
 	ContentList c = _parent->selected_text ();
 	DCPOMATIC_ASSERT (c.size() == 1);
 
-	shared_ptr<Decoder> decoder = decoder_factory (_parent->film(), c.front(), false);
+	shared_ptr<Decoder> decoder = decoder_factory (_parent->film(), c.front(), false, shared_ptr<Decoder>());
 
 	if (decoder) {
 		_text_view = new TextView (this, _parent->film(), c.front(), c.front()->text_of_original_type(_original_type), decoder, _parent->film_viewer());