Back-port v2's rename and slight extension of FrameRateConversion.

10 files changed, 161 insertions, 78 deletions

diff --git a/src/lib/audio_content.cc b/src/lib/audio_content.cc
index 79912f1ae..7d77154e1 100644
--- a/src/lib/audio_content.cc
+++ b/src/lib/audio_content.cc
@@ -25,6 +25,7 @@
 #include "film.h"
 #include "exceptions.h"
 #include "config.h"
+#include "frame_rate_change.h"
 
 #include "i18n.h"
 
@@ -159,7 +160,7 @@ AudioContent::output_audio_frame_rate () const
 	/* Resample to a DCI-approved sample rate */
 	double t = dcp_audio_frame_rate (content_audio_frame_rate ());
 
-	FrameRateConversion frc (video_frame_rate(), film->video_frame_rate());
+	FrameRateChange frc (video_frame_rate(), film->video_frame_rate());
 
 	/* Compensate if the DCP is being run at a different frame rate
 	   to the source; that is, if the video is run such that it will
@@ -168,7 +169,7 @@ AudioContent::output_audio_frame_rate () const
 	*/
 
 	if (frc.change_speed) {
-		t *= video_frame_rate() * frc.factor() / film->video_frame_rate();
+		t /= frc.speed_up;
 	}
 
 	return rint (t);
diff --git a/src/lib/ffmpeg_content.cc b/src/lib/ffmpeg_content.cc
index 4ea6dbc6a..4d886a6dd 100644
--- a/src/lib/ffmpeg_content.cc
+++ b/src/lib/ffmpeg_content.cc
@@ -31,6 +31,7 @@ extern "C" {
 #include "film.h"
 #include "log.h"
 #include "exceptions.h"
+#include "frame_rate_change.h"
 
 #include "i18n.h"
 
@@ -407,7 +408,7 @@ FFmpegContent::full_length () const
 	shared_ptr<const Film> film = _film.lock ();
 	assert (film);
 	
-	FrameRateConversion frc (video_frame_rate (), film->video_frame_rate ());
+	FrameRateChange frc (video_frame_rate (), film->video_frame_rate ());
 	return video_length_after_3d_combine() * frc.factor() * TIME_HZ / film->video_frame_rate ();
 }
 
diff --git a/src/lib/frame_rate_change.cc b/src/lib/frame_rate_change.cc
new file mode 100644
index 000000000..3e9c4b505
--- /dev/null
+++ b/src/lib/frame_rate_change.cc
@@ -0,0 +1,91 @@
+/*
+    Copyright (C) 2012-2014 Carl Hetherington <cth@carlh.net>
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+
+*/
+
+#include <cmath>
+#include "frame_rate_change.h"
+#include "compose.hpp"
+
+#include "i18n.h"
+
+static bool
+about_equal (float a, float 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);
+}
+
+
+FrameRateChange::FrameRateChange (float source, int dcp)
+	: skip (false)
+	, repeat (1)
+	, change_speed (false)
+{
+	if (fabs (source / 2.0 - dcp) < fabs (source - dcp)) {
+		/* The difference between source and DCP frame rate will be lower
+		   (i.e. better) if we skip.
+		*/
+		skip = true;
+	} else if (fabs (source * 2 - dcp) < fabs (source - dcp)) {
+		/* The difference between source and DCP frame rate would be better
+		   if we repeated each frame once; it may be better still if we
+		   repeated more than once.  Work out the required repeat.
+		*/
+		repeat = round (dcp / source);
+	}
+
+	speed_up = dcp / (source * factor());
+	change_speed = !about_equal (speed_up, 1.0);
+
+	if (!skip && repeat == 1 && !change_speed) {
+		description = _("Content and DCP have the same rate.\n");
+	} else {
+		if (skip) {
+			description = _("DCP will use every other frame of the content.\n");
+		} else if (repeat == 2) {
+			description = _("Each content frame will be doubled in the DCP.\n");
+		} else if (repeat > 2) {
+			description = String::compose (_("Each content frame will be repeated %1 more times in the DCP.\n"), repeat - 1);
+		}
+
+		if (change_speed) {
+			float const pc = dcp * 100 / (source * factor());
+			description += String::compose (_("DCP will run at %1%% of the content speed.\n"), pc);
+		}
+	}
+}
diff --git a/src/lib/frame_rate_change.h b/src/lib/frame_rate_change.h
new file mode 100644
index 000000000..6165f6840
--- /dev/null
+++ b/src/lib/frame_rate_change.h
@@ -0,0 +1,58 @@
+/*
+    Copyright (C) 2012-2014 Carl Hetherington <cth@carlh.net>
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+
+*/
+
+#include <string>
+
+struct FrameRateChange
+{
+	FrameRateChange (float, int);
+
+	/** @return factor by which to multiply a source frame rate
+	    to get the effective rate after any skip or repeat has happened.
+	*/
+	float factor () const {
+		if (skip) {
+			return 0.5;
+		}
+
+		return repeat;
+	}
+
+	/** true to skip every other frame */
+	bool skip;
+	/** number of times to use each frame (e.g. 1 is normal, 2 means repeat each frame once, and so on) */
+	int repeat;
+	/** true if this DCP will run its video faster or slower than the source
+	 *  without taking into account `repeat' nor `skip'.
+	 *  (e.g. change_speed will be true if
+	 *	    source is 29.97fps, DCP is 30fps
+	 *	    source is 14.50fps, DCP is 30fps
+	 *  but not if
+	 *	    source is 15.00fps, DCP is 30fps
+	 *	    source is 12.50fps, DCP is 25fps)
+	 */
+	bool change_speed;
+
+	/** Amount by which the video is being sped-up in the DCP; e.g. for a
+	 *  24fps source in a 25fps DCP this would be 25/24.
+	 */
+	float speed_up;
+
+	std::string description;
+};
diff --git a/src/lib/image_content.cc b/src/lib/image_content.cc
index 3b87fcf00..6acf0bab9 100644
--- a/src/lib/image_content.cc
+++ b/src/lib/image_content.cc
@@ -24,6 +24,7 @@
 #include "compose.hpp"
 #include "film.h"
 #include "job.h"
+#include "frame_rate_change.h"
 
 #include "i18n.h"
 
@@ -130,7 +131,7 @@ ImageContent::full_length () const
 	shared_ptr<const Film> film = _film.lock ();
 	assert (film);
 	
-	FrameRateConversion frc (video_frame_rate(), film->video_frame_rate ());
+	FrameRateChange frc (video_frame_rate(), film->video_frame_rate ());
 	return video_length_after_3d_combine() * frc.factor() * TIME_HZ / video_frame_rate();
 }
 
diff --git a/src/lib/player.cc b/src/lib/player.cc
index 68df8ea70..20cea7e4a 100644
--- a/src/lib/player.cc
+++ b/src/lib/player.cc
@@ -36,6 +36,7 @@
 #include "log.h"
 #include "scaler.h"
 #include "player_video_frame.h"
+#include "frame_rate_change.h"
 
 #define LOG_GENERAL(...) _film->log()->log (String::compose (__VA_ARGS__), Log::TYPE_GENERAL);
 
@@ -201,7 +202,7 @@ Player::process_video (weak_ptr<Piece> weak_piece, shared_ptr<const ImageProxy>
 	shared_ptr<VideoContent> content = dynamic_pointer_cast<VideoContent> (piece->content);
 	assert (content);
 
-	FrameRateConversion frc (content->video_frame_rate(), _film->video_frame_rate());
+	FrameRateChange frc (content->video_frame_rate(), _film->video_frame_rate());
 	if (frc.skip && (frame % 2) == 1) {
 		return;
 	}
diff --git a/src/lib/util.cc b/src/lib/util.cc
index bbe6f77e1..fa7be179a 100644
--- a/src/lib/util.cc
+++ b/src/lib/util.cc
@@ -789,44 +789,6 @@ audio_channel_name (int c)
 	return channels[c];
 }
 
-FrameRateConversion::FrameRateConversion (float source, int dcp)
-	: skip (false)
-	, repeat (1)
-	, change_speed (false)
-{
-	if (fabs (source / 2.0 - dcp) < fabs (source - dcp)) {
-		/* The difference between source and DCP frame rate will be lower
-		   (i.e. better) if we skip.
-		*/
-		skip = true;
-	} else if (fabs (source * 2 - dcp) < fabs (source - dcp)) {
-		/* The difference between source and DCP frame rate would be better
-		   if we repeated each frame once; it may be better still if we
-		   repeated more than once.  Work out the required repeat.
-		*/
-		repeat = round (dcp / source);
-	}
-
-	change_speed = !about_equal (source * factor(), dcp);
-
-	if (!skip && repeat == 1 && !change_speed) {
-		description = _("Content and DCP have the same rate.\n");
-	} else {
-		if (skip) {
-			description = _("DCP will use every other frame of the content.\n");
-		} else if (repeat == 2) {
-			description = _("Each content frame will be doubled in the DCP.\n");
-		} else if (repeat > 2) {
-			description = String::compose (_("Each content frame will be repeated %1 more times in the DCP.\n"), repeat - 1);
-		}
-
-		if (change_speed) {
-			float const pc = dcp * 100 / (source * factor());
-			description += String::compose (_("DCP will run at %1%% of the content speed.\n"), pc);
-		}
-	}
-}
-
 bool
 valid_image_file (boost::filesystem::path f)
 {
diff --git a/src/lib/util.h b/src/lib/util.h
index 5d93456df..70bf495c6 100644
--- a/src/lib/util.h
+++ b/src/lib/util.h
@@ -73,40 +73,6 @@ extern boost::shared_ptr<const libdcp::Signer> make_signer ();
 extern libdcp::Size fit_ratio_within (float ratio, libdcp::Size);
 extern std::string entities_to_text (std::string e);
 extern std::map<std::string, std::string> split_get_request (std::string url);
-
-struct FrameRateConversion
-{
-	FrameRateConversion (float, int);
-
-	/** @return factor by which to multiply a source frame rate
-	    to get the effective rate after any skip or repeat has happened.
-	*/
-	float factor () const {
-		if (skip) {
-			return 0.5;
-		}
-
-		return repeat;
-	}
-
-	/** true to skip every other frame */
-	bool skip;
-	/** number of times to use each frame (e.g. 1 is normal, 2 means repeat each frame once, and so on) */
-	int repeat;
-	/** true if this DCP will run its video faster or slower than the source
-	 *  without taking into account `repeat' nor `skip'.
-	 *  (e.g. change_speed will be true if
-	 *	    source is 29.97fps, DCP is 30fps
-	 *	    source is 14.50fps, DCP is 30fps
-	 *  but not if
-	 *	    source is 15.00fps, DCP is 30fps
-	 *	    source is 12.50fps, DCP is 25fps)
-	 */
-	bool change_speed;
-
-	std::string description;
-};
-
 extern int dcp_audio_frame_rate (int);
 extern int stride_round_up (int, int const *, int);
 extern std::multimap<std::string, std::string> read_key_value (std::istream& s);
diff --git a/src/lib/video_content.cc b/src/lib/video_content.cc
index 40772980f..ec5890b45 100644
--- a/src/lib/video_content.cc
+++ b/src/lib/video_content.cc
@@ -30,6 +30,7 @@
 #include "util.h"
 #include "film.h"
 #include "exceptions.h"
+#include "frame_rate_change.h"
 
 #include "i18n.h"
 
@@ -367,7 +368,7 @@ 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());
+	FrameRateChange 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
diff --git a/src/lib/wscript b/src/lib/wscript
index f932a142d..517ad7787 100644
--- a/src/lib/wscript
+++ b/src/lib/wscript
@@ -30,6 +30,7 @@ sources = """
           ffmpeg_examiner.cc
           film.cc
           filter.cc
+          frame_rate_change.cc
           internet.cc
           image.cc
           image_content.cc