From 8053593f2ccff66287c43d20a8f28be9919bff75 Mon Sep 17 00:00:00 2001
From: Carl Hetherington <cth@carlh.net>
Date: Tue, 29 Oct 2013 18:40:48 +0000
Subject: [PATCH] Seek past trim on setting up player pieces.

---
 ChangeLog                |  3 +++
 src/lib/player.cc        | 18 ++++++++++--------
 src/lib/video_content.cc | 20 ++++++++++++++++++++
 src/lib/video_content.h  |  2 ++
 4 files changed, 35 insertions(+), 8 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index af3093205..3a3dffd12 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,8 @@
 2013-10-29  Carl Hetherington  <cth@carlh.net>
 
+	* Improve performance when start-trimming
+	large files.
+
 	* Fix audio problems when start-trimming.
 
 2013-10-28  Carl Hetherington  <cth@carlh.net>
diff --git a/src/lib/player.cc b/src/lib/player.cc
index 8370a3f9f..53186af6e 100644
--- a/src/lib/player.cc
+++ b/src/lib/player.cc
@@ -102,7 +102,9 @@ public:
 	
 	shared_ptr<Content> content;
 	shared_ptr<Decoder> decoder;
+	/** Time of the last video we emitted relative to the start of the DCP */
 	Time video_position;
+	/** Time of the last audio we emitted relative to the start of the DCP */
 	Time audio_position;
 
 	IncomingVideo repeat_video;
@@ -408,20 +410,19 @@ Player::seek (Time t, bool accurate)
 		if (!vc) {
 			continue;
 		}
-		
+
+		/* s is the offset of t from the start position of this content */
 		Time s = t - vc->position ();
 		s = max (static_cast<Time> (0), s);
 		s = min (vc->length_after_trim(), s);
 
+		/* Hence set the piece positions to the `global' time */
 		(*i)->video_position = (*i)->audio_position = vc->position() + s;
 
-		FrameRateConversion frc (vc->video_frame_rate(), _film->video_frame_rate());
-		/* Here we are converting from time (in the DCP) to a frame number in the content.
-		   Hence we need to use the DCP's frame rate and the double/skip correction, not
-		   the source's rate.
-		*/
-		VideoContent::Frame f = (s + vc->trim_start ()) * _film->video_frame_rate() / (frc.factor() * TIME_HZ);
-		dynamic_pointer_cast<VideoDecoder>((*i)->decoder)->seek (f, accurate);
+		/* And seek the decoder */
+		dynamic_pointer_cast<VideoDecoder>((*i)->decoder)->seek (
+			vc->time_to_content_video_frames (s + vc->trim_start ()), accurate
+			);
 
 		(*i)->reset_repeat ();
 	}
@@ -455,6 +456,7 @@ Player::setup_pieces ()
 			fd->Audio.connect (bind (&Player::process_audio, this, piece, _1, _2));
 			fd->Subtitle.connect (bind (&Player::process_subtitle, this, piece, _1, _2, _3, _4));
 
+			fd->seek (fc->time_to_content_video_frames (fc->trim_start ()), true);
 			piece->decoder = fd;
 		}
 		
diff --git a/src/lib/video_content.cc b/src/lib/video_content.cc
index 347836855..d0eab4dbf 100644
--- a/src/lib/video_content.cc
+++ b/src/lib/video_content.cc
@@ -26,6 +26,8 @@
 #include "compose.hpp"
 #include "config.h"
 #include "colour_conversion.h"
+#include "util.h"
+#include "film.h"
 
 #include "i18n.h"
 
@@ -289,3 +291,21 @@ VideoContent::video_size_after_crop () const
 {
 	return crop().apply (video_size_after_3d_split ());
 }
+
+/** @param t A time offset from the start of this piece of content.
+ *  @return Corresponding frame index.
+ */
+VideoContent::Frame
+VideoContent::time_to_content_video_frames (Time t) const
+{
+	shared_ptr<const Film> film = _film.lock ();
+	assert (film);
+	
+	FrameRateConversion frc (video_frame_rate(), film->video_frame_rate());
+
+	/* Here we are converting from time (in the DCP) to a frame number in the content.
+	   Hence we need to use the DCP's frame rate and the double/skip correction, not
+	   the source's rate.
+	*/
+	return t * film->video_frame_rate() / (frc.factor() * TIME_HZ);
+}
diff --git a/src/lib/video_content.h b/src/lib/video_content.h
index 369209776..6f80536fe 100644
--- a/src/lib/video_content.h
+++ b/src/lib/video_content.h
@@ -101,6 +101,8 @@ public:
 	libdcp::Size video_size_after_3d_split () const;
 	libdcp::Size video_size_after_crop () const;
 
+	VideoContent::Frame time_to_content_video_frames (Time) const;
+
 protected:
 	void take_from_video_examiner (boost::shared_ptr<VideoExaminer>);
 
-- 
2.30.2