From 6a18a737ef8dfbfbe909afe8266f104a2125b5fb Mon Sep 17 00:00:00 2001
From: Carl Hetherington <cth@carlh.net>
Date: Wed, 1 Jun 2016 22:45:58 +0100
Subject: [PATCH 1/1] Store video frame rate in XML (#883).

---
 src/lib/content.cc           | 16 ++++++++++++++++
 src/lib/frame_rate_change.cc | 28 ++++------------------------
 src/lib/types.h              | 22 ++++++++++++++++++++++
 3 files changed, 42 insertions(+), 24 deletions(-)

diff --git a/src/lib/content.cc b/src/lib/content.cc
index 7afbf924f..66b0d477e 100644
--- a/src/lib/content.cc
+++ b/src/lib/content.cc
@@ -95,6 +95,7 @@ Content::Content (shared_ptr<const Film> film, cxml::ConstNodePtr node)
 	_position = DCPTime (node->number_child<DCPTime::Type> ("Position"));
 	_trim_start = ContentTime (node->number_child<ContentTime::Type> ("TrimStart"));
 	_trim_end = ContentTime (node->number_child<ContentTime::Type> ("TrimEnd"));
+	_video_frame_rate = node->optional_number_child<double> ("VideoFrameRate");
 }
 
 Content::Content (shared_ptr<const Film> film, vector<shared_ptr<Content> > c)
@@ -102,6 +103,7 @@ Content::Content (shared_ptr<const Film> film, vector<shared_ptr<Content> > c)
 	, _position (c.front()->position ())
 	, _trim_start (c.front()->trim_start ())
 	, _trim_end (c.back()->trim_end ())
+	, _video_frame_rate (c.front()->video_frame_rate())
 	, _change_signals_frequent (false)
 {
 	for (size_t i = 0; i < c.size(); ++i) {
@@ -113,6 +115,17 @@ Content::Content (shared_ptr<const Film> film, vector<shared_ptr<Content> > c)
 			throw JoinError (_("Only the last piece of content to be joined can have an end trim."));
 		}
 
+		if (
+			(_video_frame_rate && !c[i]->_video_frame_rate) ||
+			(!_video_frame_rate && c[i]->_video_frame_rate)
+			) {
+			throw JoinError (_("Content to be joined must have the same video frame rate"));
+		}
+
+		if (_video_frame_rate && fabs (_video_frame_rate.get() - c[i]->_video_frame_rate.get()) > VIDEO_FRAME_RATE_EPSILON) {
+			throw JoinError (_("Content to be joined must have the same video frame rate"));
+		}
+
 		for (size_t j = 0; j < c[i]->number_of_paths(); ++j) {
 			_paths.push_back (c[i]->path (j));
 		}
@@ -131,6 +144,9 @@ Content::as_xml (xmlpp::Node* node) const
 	node->add_child("Position")->add_child_text (raw_convert<string> (_position.get ()));
 	node->add_child("TrimStart")->add_child_text (raw_convert<string> (_trim_start.get ()));
 	node->add_child("TrimEnd")->add_child_text (raw_convert<string> (_trim_end.get ()));
+	if (_video_frame_rate) {
+		node->add_child("VideoFrameRate")->add_child_text (raw_convert<string> (_video_frame_rate.get()));
+	}
 }
 
 void
diff --git a/src/lib/frame_rate_change.cc b/src/lib/frame_rate_change.cc
index 8b2d6cf99..80a167029 100644
--- a/src/lib/frame_rate_change.cc
+++ b/src/lib/frame_rate_change.cc
@@ -1,5 +1,5 @@
 /*
-    Copyright (C) 2012-2015 Carl Hetherington <cth@carlh.net>
+    Copyright (C) 2012-2016 Carl Hetherington <cth@carlh.net>
 
     This file is part of DCP-o-matic.
 
@@ -18,9 +18,10 @@
 
 */
 
-#include <cmath>
 #include "frame_rate_change.h"
+#include "types.h"
 #include "compose.hpp"
+#include <cmath>
 
 #include "i18n.h"
 
@@ -29,28 +30,7 @@ using std::string;
 static bool
 about_equal (double a, double b)
 {
-	/* A film of F seconds at f FPS will be Ff frames;
-	   Consider some delta FPS d, so if we run the same
-	   film at (f + d) FPS it will last F(f + d) seconds.
-
-	   Hence the difference in length over the length of the film will
-	   be F(f + d) - Ff frames
-	    = Ff + Fd - Ff frames
-	    = Fd frames
-	    = Fd/f seconds
-
-	   So if we accept a difference of 1 frame, ie 1/f seconds, we can
-	   say that
-
-	   1/f = Fd/f
-	ie 1 = Fd
-	ie d = 1/F
-
-	   So for a 3hr film, ie F = 3 * 60 * 60 = 10800, the acceptable
-	   FPS error is 1/F ~= 0.0001 ~= 10-e4
-	*/
-
-	return (fabs (a - b) < 1e-4);
+	return (fabs (a - b) < VIDEO_FRAME_RATE_EPSILON);
 }
 
 
diff --git a/src/lib/types.h b/src/lib/types.h
index d9bee97c6..ab51e38a9 100644
--- a/src/lib/types.h
+++ b/src/lib/types.h
@@ -48,6 +48,28 @@ namespace xmlpp {
  */
 #define SERVER_LINK_VERSION (64+0)
 
+/** A film of F seconds at f FPS will be Ff frames;
+    Consider some delta FPS d, so if we run the same
+    film at (f + d) FPS it will last F(f + d) seconds.
+
+    Hence the difference in length over the length of the film will
+    be F(f + d) - Ff frames
+    = Ff + Fd - Ff frames
+    = Fd frames
+    = Fd/f seconds
+
+    So if we accept a difference of 1 frame, ie 1/f seconds, we can
+    say that
+
+    1/f = Fd/f
+    ie 1 = Fd
+    ie d = 1/F
+
+    So for a 3hr film, ie F = 3 * 60 * 60 = 10800, the acceptable
+    FPS error is 1/F ~= 0.0001 ~= 1e-4
+*/
+#define VIDEO_FRAME_RATE_EPSILON (1e-4)
+
 typedef std::vector<boost::shared_ptr<Content> > ContentList;
 typedef std::vector<boost::shared_ptr<FFmpegContent> > FFmpegContentList;
 
-- 
2.30.2