X-Git-Url: https://git.carlh.net/gitweb/?a=blobdiff_plain;f=src%2Flib%2Fvideo_content.cc;h=1e8b9034a6242463a60389458e810a23df334eb9;hb=c07707e9ba362786c9a22c51e5310a9f0e56ff3d;hp=b33a37cb8ce385892d3b2aac663e05857e46cc1d;hpb=a79d78d8bb6d51f6662f1f63b9f8fd19e1a0c5f1;p=dcpomatic.git

diff --git a/src/lib/video_content.cc b/src/lib/video_content.cc
index b33a37cb8..1e8b9034a 100644
--- a/src/lib/video_content.cc
+++ b/src/lib/video_content.cc
@@ -1,5 +1,5 @@
 /*
-    Copyright (C) 2013-2014 Carl Hetherington <cth@carlh.net>
+    Copyright (C) 2013-2015 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
@@ -17,9 +17,6 @@
 
 */
 
-#include <iomanip>
-#include <libcxml/cxml.h>
-#include <dcp/colour_matrix.h>
 #include "video_content.h"
 #include "video_examiner.h"
 #include "compose.hpp"
@@ -29,66 +26,89 @@
 #include "util.h"
 #include "film.h"
 #include "exceptions.h"
+#include "frame_rate_change.h"
+#include "log.h"
+#include "safe_stringstream.h"
+#include "raw_convert.h"
+#include <libcxml/cxml.h>
+#include <dcp/colour_matrix.h>
+#include <libxml++/libxml++.h>
+#include <iomanip>
+#include <iostream>
 
 #include "i18n.h"
 
+#define LOG_GENERAL(...) film->log()->log (String::compose (__VA_ARGS__), LogEntry::TYPE_GENERAL);
+
 int const VideoContentProperty::VIDEO_SIZE	  = 0;
 int const VideoContentProperty::VIDEO_FRAME_RATE  = 1;
 int const VideoContentProperty::VIDEO_FRAME_TYPE  = 2;
 int const VideoContentProperty::VIDEO_CROP	  = 3;
 int const VideoContentProperty::VIDEO_SCALE	  = 4;
 int const VideoContentProperty::COLOUR_CONVERSION = 5;
+int const VideoContentProperty::VIDEO_FADE_IN     = 6;
+int const VideoContentProperty::VIDEO_FADE_OUT    = 7;
 
 using std::string;
-using std::stringstream;
 using std::setprecision;
 using std::cout;
 using std::vector;
+using std::min;
+using std::max;
+using std::stringstream;
+using std::fixed;
+using std::setprecision;
+using std::list;
+using std::pair;
 using boost::shared_ptr;
-using boost::lexical_cast;
 using boost::optional;
 using boost::dynamic_pointer_cast;
 
-vector<VideoContentScale> VideoContentScale::_scales;
-
-VideoContent::VideoContent (shared_ptr<const Film> f)
-	: Content (f)
+VideoContent::VideoContent (shared_ptr<const Film> film)
+	: Content (film)
 	, _video_length (0)
 	, _video_frame_rate (0)
 	, _video_frame_type (VIDEO_FRAME_TYPE_2D)
-	, _scale (Ratio::from_id ("185"))
+	, _scale (VideoContentScale (Ratio::from_id ("178")))
+	, _fade_in (0)
+	, _fade_out (0)
 {
-	setup_default_colour_conversion ();
+	set_default_colour_conversion ();
 }
 
-VideoContent::VideoContent (shared_ptr<const Film> f, DCPTime s, ContentTime len)
-	: Content (f, s)
+VideoContent::VideoContent (shared_ptr<const Film> film, DCPTime s, Frame len)
+	: Content (film, s)
 	, _video_length (len)
 	, _video_frame_rate (0)
 	, _video_frame_type (VIDEO_FRAME_TYPE_2D)
-	, _scale (Ratio::from_id ("185"))
+	, _scale (VideoContentScale (Ratio::from_id ("178")))
+	, _fade_in (0)
+	, _fade_out (0)
 {
-	setup_default_colour_conversion ();
+	set_default_colour_conversion ();
 }
 
-VideoContent::VideoContent (shared_ptr<const Film> f, boost::filesystem::path p)
-	: Content (f, p)
+VideoContent::VideoContent (shared_ptr<const Film> film, boost::filesystem::path p)
+	: Content (film, p)
 	, _video_length (0)
 	, _video_frame_rate (0)
 	, _video_frame_type (VIDEO_FRAME_TYPE_2D)
-	, _scale (Ratio::from_id ("185"))
+	, _scale (VideoContentScale (Ratio::from_id ("178")))
+	, _fade_in (0)
+	, _fade_out (0)
 {
-	setup_default_colour_conversion ();
+	set_default_colour_conversion ();
 }
 
-VideoContent::VideoContent (shared_ptr<const Film> f, shared_ptr<const cxml::Node> node, int version)
-	: Content (f, node)
+VideoContent::VideoContent (shared_ptr<const Film> film, cxml::ConstNodePtr node, int version)
+	: Content (film, node)
 {
-	_video_length = ContentTime (node->number_child<int64_t> ("VideoLength"));
 	_video_size.width = node->number_child<int> ("VideoWidth");
 	_video_size.height = node->number_child<int> ("VideoHeight");
-	_video_frame_rate = node->number_child<float> ("VideoFrameRate");
+	_video_frame_rate = node->number_child<double> ("VideoFrameRate");
+	_video_length = node->number_child<Frame> ("VideoLength");
 	_video_frame_type = static_cast<VideoFrameType> (node->number_child<int> ("VideoFrameType"));
+	_sample_aspect_ratio = node->optional_number_child<double> ("SampleAspectRatio");
 	_crop.left = node->number_child<int> ("LeftCrop");
 	_crop.right = node->number_child<int> ("RightCrop");
 	_crop.top = node->number_child<int> ("TopCrop");
@@ -102,16 +122,25 @@ VideoContent::VideoContent (shared_ptr<const Film> f, shared_ptr<const cxml::Nod
 	} else {
 		_scale = VideoContentScale (node->node_child ("Scale"));
 	}
-	
-	_colour_conversion = ColourConversion (node->node_child ("ColourConversion"));
+
+
+	if (node->optional_node_child ("ColourConversion")) {
+		_colour_conversion = ColourConversion (node->node_child ("ColourConversion"), version);
+	}
+	if (version >= 32) {
+		_fade_in = node->number_child<Frame> ("FadeIn");
+		_fade_out = node->number_child<Frame> ("FadeOut");
+	} else {
+		_fade_in = _fade_out = 0;
+	}
 }
 
-VideoContent::VideoContent (shared_ptr<const Film> f, vector<shared_ptr<Content> > c)
-	: Content (f, c)
+VideoContent::VideoContent (shared_ptr<const Film> film, vector<shared_ptr<Content> > c)
+	: Content (film, c)
 	, _video_length (0)
 {
 	shared_ptr<VideoContent> ref = dynamic_pointer_cast<VideoContent> (c[0]);
-	assert (ref);
+	DCPOMATIC_ASSERT (ref);
 
 	for (size_t i = 0; i < c.size(); ++i) {
 		shared_ptr<VideoContent> vc = dynamic_pointer_cast<VideoContent> (c[i]);
@@ -140,6 +169,10 @@ VideoContent::VideoContent (shared_ptr<const Film> f, vector<shared_ptr<Content>
 			throw JoinError (_("Content to be joined must have the same colour conversion."));
 		}
 
+		if (vc->fade_in() != ref->fade_in() || vc->fade_out() != ref->fade_out()) {
+			throw JoinError (_("Content to be joined must have the same fades."));
+		}
+
 		_video_length += vc->video_length ();
 	}
 
@@ -149,29 +182,37 @@ VideoContent::VideoContent (shared_ptr<const Film> f, vector<shared_ptr<Content>
 	_crop = ref->crop ();
 	_scale = ref->scale ();
 	_colour_conversion = ref->colour_conversion ();
+	_fade_in = ref->fade_in ();
+	_fade_out = ref->fade_out ();
 }
 
 void
 VideoContent::as_xml (xmlpp::Node* node) const
 {
 	boost::mutex::scoped_lock lm (_mutex);
-	node->add_child("VideoLength")->add_child_text (lexical_cast<string> (_video_length));
-	node->add_child("VideoWidth")->add_child_text (lexical_cast<string> (_video_size.width));
-	node->add_child("VideoHeight")->add_child_text (lexical_cast<string> (_video_size.height));
-	node->add_child("VideoFrameRate")->add_child_text (lexical_cast<string> (_video_frame_rate));
-	node->add_child("VideoFrameType")->add_child_text (lexical_cast<string> (static_cast<int> (_video_frame_type)));
-	node->add_child("LeftCrop")->add_child_text (boost::lexical_cast<string> (_crop.left));
-	node->add_child("RightCrop")->add_child_text (boost::lexical_cast<string> (_crop.right));
-	node->add_child("TopCrop")->add_child_text (boost::lexical_cast<string> (_crop.top));
-	node->add_child("BottomCrop")->add_child_text (boost::lexical_cast<string> (_crop.bottom));
+	node->add_child("VideoLength")->add_child_text (raw_convert<string> (_video_length));
+	node->add_child("VideoWidth")->add_child_text (raw_convert<string> (_video_size.width));
+	node->add_child("VideoHeight")->add_child_text (raw_convert<string> (_video_size.height));
+	node->add_child("VideoFrameRate")->add_child_text (raw_convert<string> (_video_frame_rate));
+	node->add_child("VideoFrameType")->add_child_text (raw_convert<string> (static_cast<int> (_video_frame_type)));
+	if (_sample_aspect_ratio) {
+		node->add_child("SampleAspectRatio")->add_child_text (raw_convert<string> (_sample_aspect_ratio.get ()));
+	}
+	_crop.as_xml (node);
 	_scale.as_xml (node->add_child("Scale"));
-	_colour_conversion.as_xml (node->add_child("ColourConversion"));
+	if (_colour_conversion) {
+		_colour_conversion.get().as_xml (node->add_child("ColourConversion"));
+	}
+	node->add_child("FadeIn")->add_child_text (raw_convert<string> (_fade_in));
+	node->add_child("FadeOut")->add_child_text (raw_convert<string> (_fade_out));
 }
 
 void
-VideoContent::setup_default_colour_conversion ()
+VideoContent::set_default_colour_conversion ()
 {
-	_colour_conversion = PresetColourConversion (_("sRGB"), 2.4, true, dcp::colour_matrix::srgb_to_xyz, 2.6).conversion;
+	/* If there's no better offer we'll use Rec. 709 */
+	boost::mutex::scoped_lock lm (_mutex);
+	_colour_conversion = PresetColourConversion::from_id ("rec709").conversion;
 }
 
 void
@@ -179,36 +220,34 @@ VideoContent::take_from_video_examiner (shared_ptr<VideoExaminer> d)
 {
 	/* These examiner calls could call other content methods which take a lock on the mutex */
 	dcp::Size const vs = d->video_size ();
-	float const vfr = d->video_frame_rate ();
-	
+	optional<double> const vfr = d->video_frame_rate ();
+	Frame vl = d->video_length ();
+	optional<double> const ar = d->sample_aspect_ratio ();
+
 	{
 		boost::mutex::scoped_lock lm (_mutex);
 		_video_size = vs;
-		_video_frame_rate = vfr;
+		/* Default video frame rate to 24fps if the examiner doesn't know */
+		_video_frame_rate = vfr.get_value_or (24);
+		_video_length = vl;
+		_sample_aspect_ratio = ar;
+
+		/* Guess correct scale from size and sample aspect ratio */
+		_scale = VideoContentScale (
+			Ratio::nearest_from_ratio (double (_video_size.width) * ar.get_value_or (1) / _video_size.height)
+			);
 	}
-	
-	signal_changed (VideoContentProperty::VIDEO_SIZE);
-	signal_changed (VideoContentProperty::VIDEO_FRAME_RATE);
-}
 
+	shared_ptr<const Film> film = _film.lock ();
+	DCPOMATIC_ASSERT (film);
+	LOG_GENERAL ("Video length obtained from header as %1 frames", _video_length);
 
-string
-VideoContent::information () const
-{
-	if (video_size().width == 0 || video_size().height == 0) {
-		return "";
-	}
-	
-	stringstream s;
+	set_default_colour_conversion ();
 
-	s << String::compose (
-		_("%1x%2 pixels (%3:1)"),
-		video_size().width,
-		video_size().height,
-		setprecision (3), video_size().ratio ()
-		);
-	
-	return s.str ();
+	signal_changed (VideoContentProperty::VIDEO_SIZE);
+	signal_changed (VideoContentProperty::VIDEO_FRAME_RATE);
+	signal_changed (VideoContentProperty::VIDEO_SCALE);
+	signal_changed (ContentProperty::LENGTH);
 }
 
 void
@@ -216,14 +255,14 @@ VideoContent::set_left_crop (int c)
 {
 	{
 		boost::mutex::scoped_lock lm (_mutex);
-		
+
 		if (_crop.left == c) {
 			return;
 		}
-		
+
 		_crop.left = c;
 	}
-	
+
 	signal_changed (VideoContentProperty::VIDEO_CROP);
 }
 
@@ -235,10 +274,10 @@ VideoContent::set_right_crop (int c)
 		if (_crop.right == c) {
 			return;
 		}
-		
+
 		_crop.right = c;
 	}
-	
+
 	signal_changed (VideoContentProperty::VIDEO_CROP);
 }
 
@@ -250,10 +289,10 @@ VideoContent::set_top_crop (int c)
 		if (_crop.top == c) {
 			return;
 		}
-		
+
 		_crop.top = c;
 	}
-	
+
 	signal_changed (VideoContentProperty::VIDEO_CROP);
 }
 
@@ -265,7 +304,7 @@ VideoContent::set_bottom_crop (int c)
 		if (_crop.bottom == c) {
 			return;
 		}
-		
+
 		_crop.bottom = c;
 	}
 
@@ -291,14 +330,19 @@ VideoContent::set_scale (VideoContentScale s)
 string
 VideoContent::identifier () const
 {
-	stringstream s;
+	SafeStringStream s;
 	s << Content::identifier()
 	  << "_" << crop().left
 	  << "_" << crop().right
 	  << "_" << crop().top
 	  << "_" << crop().bottom
 	  << "_" << scale().id()
-	  << "_" << colour_conversion().identifier ();
+	  << "_" << _fade_in
+	  << "_" << _fade_out;
+
+	if (colour_conversion()) {
+		s << "_" << colour_conversion().get().identifier ();
+	}
 
 	return s.str ();
 }
@@ -317,7 +361,19 @@ VideoContent::set_video_frame_type (VideoFrameType t)
 string
 VideoContent::technical_summary () const
 {
-	return String::compose ("video: length %1, size %2x%3, rate %4", video_length(), video_size().width, video_size().height, video_frame_rate());
+	string s = String::compose (
+		N_("video: length %1 frames, size %2x%3, rate %4"),
+		video_length_after_3d_combine(),
+		video_size().width,
+		video_size().height,
+		video_frame_rate()
+		);
+
+	if (sample_aspect_ratio ()) {
+		s += String::compose (N_(", sample aspect ratio %1"), (sample_aspect_ratio().get ()));
+	}
+
+	return s;
 }
 
 dcp::Size
@@ -326,6 +382,9 @@ VideoContent::video_size_after_3d_split () const
 	dcp::Size const s = video_size ();
 	switch (video_frame_type ()) {
 	case VIDEO_FRAME_TYPE_2D:
+	case VIDEO_FRAME_TYPE_3D_ALTERNATE:
+	case VIDEO_FRAME_TYPE_3D_LEFT:
+	case VIDEO_FRAME_TYPE_3D_RIGHT:
 		return s;
 	case VIDEO_FRAME_TYPE_3D_LEFT_RIGHT:
 		return dcp::Size (s.width / 2, s.height);
@@ -333,7 +392,18 @@ VideoContent::video_size_after_3d_split () const
 		return dcp::Size (s.width, s.height / 2);
 	}
 
-	assert (false);
+	DCPOMATIC_ASSERT (false);
+}
+
+void
+VideoContent::unset_colour_conversion ()
+{
+	{
+		boost::mutex::scoped_lock lm (_mutex);
+		_colour_conversion = boost::optional<ColourConversion> ();
+	}
+
+	signal_changed (VideoContentProperty::COLOUR_CONVERSION);
 }
 
 void
@@ -347,6 +417,28 @@ VideoContent::set_colour_conversion (ColourConversion c)
 	signal_changed (VideoContentProperty::COLOUR_CONVERSION);
 }
 
+void
+VideoContent::set_fade_in (Frame t)
+{
+	{
+		boost::mutex::scoped_lock lm (_mutex);
+		_fade_in = t;
+	}
+
+	signal_changed (VideoContentProperty::VIDEO_FADE_IN);
+}
+
+void
+VideoContent::set_fade_out (Frame t)
+{
+	{
+		boost::mutex::scoped_lock lm (_mutex);
+		_fade_out = t;
+	}
+
+	signal_changed (VideoContentProperty::VIDEO_FADE_OUT);
+}
+
 /** @return Video size after 3D split and crop */
 dcp::Size
 VideoContent::video_size_after_crop () const
@@ -354,123 +446,147 @@ 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 time with respect to the content.
- */
-ContentTime
-VideoContent::dcp_time_to_content_time (DCPTime t) const
+void
+VideoContent::scale_and_crop_to_fit_width ()
 {
 	shared_ptr<const Film> film = _film.lock ();
-	assert (film);
-	return ContentTime (t, FrameRateChange (video_frame_rate(), film->video_frame_rate()));
-}
+	DCPOMATIC_ASSERT (film);
 
-VideoContentScale::VideoContentScale (Ratio const * r)
-	: _ratio (r)
-	, _scale (true)
-{
+	set_scale (VideoContentScale (film->container ()));
 
+	int const crop = max (0, int (video_size().height - double (film->frame_size().height) * video_size().width / film->frame_size().width));
+	set_top_crop (crop / 2);
+	set_bottom_crop (crop / 2);
 }
 
-VideoContentScale::VideoContentScale ()
-	: _ratio (0)
-	, _scale (false)
+void
+VideoContent::scale_and_crop_to_fit_height ()
 {
+	shared_ptr<const Film> film = _film.lock ();
+	DCPOMATIC_ASSERT (film);
 
-}
-
-VideoContentScale::VideoContentScale (bool scale)
-	: _ratio (0)
-	, _scale (scale)
-{
+	set_scale (VideoContentScale (film->container ()));
 
+	int const crop = max (0, int (video_size().width - double (film->frame_size().width) * video_size().height / film->frame_size().height));
+	set_left_crop (crop / 2);
+	set_right_crop (crop / 2);
 }
 
-VideoContentScale::VideoContentScale (shared_ptr<cxml::Node> node)
-	: _ratio (0)
-	, _scale (true)
+void
+VideoContent::set_video_frame_rate (double r)
 {
-	optional<string> r = node->optional_string_child ("Ratio");
-	if (r) {
-		_ratio = Ratio::from_id (r.get ());
-	} else {
-		_scale = node->bool_child ("Scale");
+	{
+		boost::mutex::scoped_lock lm (_mutex);
+		if (_video_frame_rate == r) {
+			return;
+		}
+
+		_video_frame_rate = r;
 	}
+
+	signal_changed (VideoContentProperty::VIDEO_FRAME_RATE);
 }
 
-void
-VideoContentScale::as_xml (xmlpp::Node* node) const
+optional<double>
+VideoContent::fade (Frame f) const
 {
-	if (_ratio) {
-		node->add_child("Ratio")->add_child_text (_ratio->id ());
-	} else {
-		node->add_child("Scale")->add_child_text (_scale ? "1" : "0");
+	DCPOMATIC_ASSERT (f >= 0);
+
+	if (f < fade_in()) {
+		return double (f) / fade_in();
 	}
-}
 
-string
-VideoContentScale::id () const
-{
-	stringstream s;
-	
-	if (_ratio) {
-		s << _ratio->id () << "_";
-	} else {
-		s << (_scale ? "S1" : "S0");
+	Frame fade_out_start = video_length() - fade_out();
+	if (f >= fade_out_start) {
+		return 1 - double (f - fade_out_start) / fade_out();
 	}
-	
-	return s.str ();
+
+	return optional<double> ();
 }
 
 string
-VideoContentScale::name () const
+VideoContent::processing_description () const
 {
-	if (_ratio) {
-		return _ratio->nickname ();
-	}
+	/* stringstream is OK here as this string is just for presentation to the user */
+	stringstream d;
+
+	if (video_size().width && video_size().height) {
+		d << String::compose (
+			_("Content video is %1x%2"),
+			video_size_after_3d_split().width,
+			video_size_after_3d_split().height
+			);
+
+
+		double ratio = video_size_after_3d_split().ratio ();
 
-	if (_scale) {
-		return _("No stretch");
+		if (sample_aspect_ratio ()) {
+			d << ", " << _("pixel aspect ratio") << " " << fixed << setprecision(2) << sample_aspect_ratio().get () << ":1";
+			ratio *= sample_aspect_ratio().get ();
+		}
+
+		d << "\n" << _("Display aspect ratio") << " " << fixed << setprecision(2) << ratio << ":1\n";
 	}
 
-	return _("No scale");
-}
+	if ((crop().left || crop().right || crop().top || crop().bottom) && video_size() != dcp::Size (0, 0)) {
+		dcp::Size cropped = video_size_after_crop ();
+		d << String::compose (
+			_("Cropped to %1x%2"),
+			cropped.width, cropped.height
+			);
 
-libdcp::Size
-VideoContentScale::size (shared_ptr<const VideoContent> c, libdcp::Size container) const
-{
-	if (_ratio) {
-		return fit_ratio_within (_ratio->ratio (), container);
+		d << " (" << fixed << setprecision(2) << cropped.ratio () << ":1)\n";
 	}
 
-	/* Force scale if the container is smaller than the content's image */
-	if (_scale || container.width < c->video_size().width || container.height < c->video_size().height) {
-		return fit_ratio_within (c->video_size().ratio (), container);
+	shared_ptr<const Film> film = _film.lock ();
+	DCPOMATIC_ASSERT (film);
+
+	dcp::Size const container_size = film->frame_size ();
+	dcp::Size const scaled = scale().size (dynamic_pointer_cast<const VideoContent> (shared_from_this ()), container_size, container_size);
+
+	if (scaled != video_size_after_crop ()) {
+		d << String::compose (
+			_("Scaled to %1x%2"),
+			scaled.width, scaled.height
+			);
+
+		d << " (" << fixed << setprecision(2) << scaled.ratio() << ":1)\n";
 	}
 
-	return c->video_size ();
-}
+	if (scaled != container_size) {
+		d << String::compose (
+			_("Padded with black to fit container %1 (%2x%3)"),
+			film->container()->nickname (),
+			container_size.width, container_size.height
+			);
 
-void
-VideoContentScale::setup_scales ()
-{
-	vector<Ratio const *> ratios = Ratio::all ();
-	for (vector<Ratio const *>::const_iterator i = ratios.begin(); i != ratios.end(); ++i) {
-		_scales.push_back (VideoContentScale (*i));
+		d << " (" << fixed << setprecision(2) << container_size.ratio () << ":1)\n";
 	}
 
-	_scales.push_back (VideoContentScale (true));
-	_scales.push_back (VideoContentScale (false));
+	d << _("Content frame rate");
+	d << " " << fixed << setprecision(4) << video_frame_rate() << "\n";
+
+	FrameRateChange frc (video_frame_rate(), film->video_frame_rate ());
+	d << frc.description () << "\n";
+
+	return d.str ();
 }
 
-bool
-operator== (VideoContentScale const & a, VideoContentScale const & b)
+void
+VideoContent::add_properties (list<pair<string, string> >& p) const
 {
-	return (a.ratio() == b.ratio() && a.scale() == b.scale());
+	p.push_back (make_pair (_("Video length"), raw_convert<string> (video_length ()) + " " + _("video frames")));
+	p.push_back (make_pair (_("Video size"), raw_convert<string> (video_size().width) + "x" + raw_convert<string> (video_size().height)));
+	p.push_back (make_pair (_("Video frame rate"), raw_convert<string> (video_frame_rate()) + " " + _("frames per second")));
 }
 
-bool
-operator!= (VideoContentScale const & a, VideoContentScale const & b)
+list<DCPTime>
+VideoContent::reel_split_points () const
 {
-	return (a.ratio() != b.ratio() || a.scale() != b.scale());
+	list<DCPTime> t;
+	shared_ptr<const Film> film = _film.lock ();
+	DCPOMATIC_ASSERT (film);
+	/* XXX: this is questionable; perhaps the position should be forced to be on a frame boundary */
+	t.push_back (position().round_up (film->video_frame_rate()));
+	return t;
 }