It seems likely that SSA font sizes should be interpreted as

1 point == 1 pixel; let's try that.

diff --git a/src/ssa_reader.cc b/src/ssa_reader.cc
index 03d20dd53f1c2f055e624497f431c41acb697b6b..863225112d2fab532e2271d939f82a15b908a8cf 100644 (file)
--- a/src/ssa_reader.cc
+++ b/src/ssa_reader.cc
@@ -147,7 +147,7 @@ public:
 
        string name;
        optional<string> font_name;
-       int font_size;
+       int font_size; ///< points
        Colour primary_colour;
        /** outline colour */
        optional<Colour> back_colour;
@@ -243,7 +243,7 @@ SSAReader::parse_style (RawSubtitle& sub, string style, int play_res_x, int play
                sub.vertical_position.proportional = raw_convert<float>(bits[2]) / play_res_y;
        } else if (boost::starts_with(style, "\\fs")) {
                SUB_ASSERT (style.length() > 3);
-               sub.font_size.set_points (raw_convert<int>(style.substr(3)));
+               sub.font_size.set_proportional(raw_convert<float>(style.substr(3)) / play_res_y);
        } else if (boost::starts_with(style, "\\c")) {
                /* \c&Hbbggrr& */
                if (style.length() <= 2) {
@@ -285,8 +285,8 @@ SSAReader::parse_line (RawSubtitle base, string line, int play_res_x, int play_r
           in pixels and in that case we must know how big the subtitle
           lines are to work out the position on screen.
        */
-       if (!current.font_size.points()) {
-               current.font_size.set_points (72);
+       if (!current.font_size.proportional()) {
+               current.font_size.set_proportional(72.0 / play_res_y);
        }
 
        /* Count the number of line breaks */
@@ -299,8 +299,8 @@ SSAReader::parse_line (RawSubtitle base, string line, int play_res_x, int play_r
                }
        }
 
-       /* Imagine that the screen is 792 points (i.e. 11 inches) high (as with DCP) */
-       double const line_size = current.font_size.proportional(792) * 1.2;
+       /* There are vague indications that with ASS 1 point should equal 1 pixel */
+       double const line_size = current.font_size.proportional(play_res_y) * 1.2;
 
        for (size_t i = 0; i < line.length(); ++i) {
                char const c = line[i];
@@ -479,7 +479,7 @@ SSAReader::read (function<optional<string> ()> get_line)
                                                SUB_ASSERT (styles.find(event[i]) != styles.end());
                                                Style style = styles[event[i]];
                                                sub.font = style.font_name;
-                                               sub.font_size = FontSize::from_points (style.font_size);
+                                               sub.font_size = FontSize::from_proportional(static_cast<float>(style.font_size) / play_res_y);
                                                sub.colour = style.primary_colour;
                                                sub.effect_colour = style.back_colour;
                                                sub.bold = style.bold;

diff --git a/test/ssa_reader_test.cc b/test/ssa_reader_test.cc
index 59a161bc3d172b2def0d9e9fef926e68b46788cb..f0eb504cc72175152cb297fcd48c7ccd730bec7b 100644 (file)
--- a/test/ssa_reader_test.cc
+++ b/test/ssa_reader_test.cc
@@ -17,20 +17,23 @@
 
 */
 
-#include "test.h"
-#include "ssa_reader.h"
+
 #include "collect.h"
-#include "subtitle.h"
 #include "exceptions.h"
+#include "ssa_reader.h"
+#include "subtitle.h"
+#include "test.h"
 #include <boost/test/unit_test.hpp>
 #include <boost/filesystem.hpp>
 #include <cstdio>
 #include <cmath>
 #include <iostream>
 
+
 using std::fabs;
 using std::vector;
 
+
 BOOST_AUTO_TEST_CASE (ssa_reader_test)
 {
        boost::filesystem::path p = private_test / "example.ssa";
@@ -41,6 +44,11 @@ BOOST_AUTO_TEST_CASE (ssa_reader_test)
 
        auto i = subs.begin ();
 
+       /* Convert a font size in points to a proportional size for this file */
+       auto fs = [](int x) {
+               return static_cast<float>(x) / 1024;
+       };
+
        BOOST_REQUIRE (i != subs.end ());
        BOOST_CHECK_EQUAL (i->from, sub::Time::from_hms (0, 2, 40, 650));
        BOOST_CHECK_EQUAL (i->to, sub::Time::from_hms (0, 2, 41, 790));
@@ -50,7 +58,7 @@ BOOST_AUTO_TEST_CASE (ssa_reader_test)
        sub::Block b = j->blocks.front ();
        BOOST_CHECK_EQUAL (b.text, "Et les enregistrements de ses ondes delta ?");
        BOOST_CHECK_EQUAL (b.font.get(), "Wolf_Rain");
-       BOOST_CHECK_EQUAL (b.font_size.points().get(), 56);
+       BOOST_CHECK_CLOSE(b.font_size.proportional().get(), fs(56), 0.1);
        BOOST_CHECK_EQUAL (b.bold, false);
        BOOST_CHECK_EQUAL (b.italic, false);
        BOOST_CHECK_EQUAL (b.underline, false);
@@ -65,7 +73,7 @@ BOOST_AUTO_TEST_CASE (ssa_reader_test)
        b = j->blocks.front ();
        BOOST_CHECK_EQUAL (b.text, "Toujours rien.");
        BOOST_CHECK_EQUAL (b.font.get(), "Wolf_Rain");
-       BOOST_CHECK_EQUAL (b.font_size.points().get(), 56);
+       BOOST_CHECK_CLOSE(b.font_size.proportional().get(), fs(56), 0.1);
        BOOST_CHECK_EQUAL (b.bold, false);
        BOOST_CHECK_EQUAL (b.italic, false);
        BOOST_CHECK_EQUAL (b.underline, false);
@@ -74,6 +82,7 @@ BOOST_AUTO_TEST_CASE (ssa_reader_test)
        BOOST_CHECK (i == subs.end());
 }
 
+
 BOOST_AUTO_TEST_CASE (ssa_reader_line_test1)
 {
        sub::RawSubtitle base;
@@ -104,6 +113,7 @@ BOOST_AUTO_TEST_CASE (ssa_reader_line_test1)
        BOOST_REQUIRE (i == r.end ());
 }
 
+
 BOOST_AUTO_TEST_CASE (ssa_reader_line_test2)
 {
        sub::RawSubtitle base;
@@ -113,6 +123,11 @@ BOOST_AUTO_TEST_CASE (ssa_reader_line_test2)
                1920, 1080
                );
 
+       /* Convert a font size in points to a vertical position for this file */
+       auto vp = [](int x) {
+               return x * 1.2 / 1080;
+       };
+
        auto i = r.begin ();
        BOOST_CHECK_EQUAL (i->text, "It's all just italics");
        BOOST_CHECK_EQUAL (i->italic, true);
@@ -128,13 +143,14 @@ BOOST_AUTO_TEST_CASE (ssa_reader_line_test2)
        i = r.begin ();
        BOOST_CHECK_EQUAL (i->text, "Italic");
        BOOST_CHECK_EQUAL (i->italic, true);
-       BOOST_CHECK (fabs ((72.0 * 1.2 / 792) - i->vertical_position.proportional.get()) < 1e-5);
+       BOOST_CHECK(fabs(vp(72) - i->vertical_position.proportional.get()) < 1e-5);
        ++i;
        BOOST_CHECK_EQUAL (i->text, "and new line");
        BOOST_CHECK_EQUAL (i->italic, false);
        BOOST_CHECK (i->vertical_position.proportional.get() < 1e-5);
 }
 
+
 static void
 test (boost::filesystem::path p)
 {
@@ -175,7 +191,7 @@ BOOST_AUTO_TEST_CASE (ssa_reader_test2)
        BOOST_REQUIRE (k != j->blocks.end ()); \
        BOOST_CHECK_EQUAL (k->text, t); \
         BOOST_CHECK_EQUAL (k->font.get(), f); \
-       BOOST_CHECK_EQUAL (k->font_size.points().get(), s); \
+       BOOST_CHECK_CLOSE(k->font_size.proportional().get(), s, 0.1); \
        BOOST_CHECK_EQUAL (k->bold, b); \
        BOOST_CHECK_EQUAL (k->italic, i); \
        BOOST_CHECK_EQUAL (k->underline, u); \
@@ -193,14 +209,24 @@ BOOST_AUTO_TEST_CASE (ssa_reader_test3)
        fclose (f);
        auto subs = sub::collect<vector<sub::Subtitle>> (reader.subtitles());
 
+       /* Convert a font size in points to a proportional size for this file */
+       auto fs = [](int x) {
+               return static_cast<float>(x) / 1080;
+       };
+
+       /* Convert a font size in points to a vertical position for this file */
+       auto vp = [&fs](int x) {
+               return fs(x) * 1.2;
+       };
+
        auto i = subs.begin();
        vector<sub::Line>::iterator j;
        vector<sub::Block>::iterator k;
 
        /* Hello world */
        SUB_START (sub::Time::from_hms (0, 0, 1, 230), sub::Time::from_hms (0, 0, 4, 550));
-       LINE ((10.0 / 1080), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK ("Hello world", "Arial", 20, false, false, false);
+       LINE((10.0 / 1080), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
+       BLOCK("Hello world", "Arial", fs(20), false, false, false);
        SUB_END();
 
        /* This is vertically moved\nand has two lines. */
@@ -209,71 +235,72 @@ BOOST_AUTO_TEST_CASE (ssa_reader_test3)
           points, 1.2 times spaced, as a proportion of the total
           screen height 729 points) up.
        */
-       LINE((900.0 / 1080) - (20.0 * 1.2 / 792), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK("This is vertically moved", "Arial", 20, false, false, false);
+       LINE((900.0 / 1080) - vp(20), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
+       BLOCK("This is vertically moved", "Arial", fs(20), false, false, false);
        LINE((900.0 / 1080), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK("and has two lines.", "Arial", 20, false, false, false);
+       BLOCK("and has two lines.", "Arial", fs(20), false, false, false);
        SUB_END();
 
        /* Some {\i1}italics{\i} are here. */
        SUB_START (sub::Time::from_hms (0, 0, 7, 740), sub::Time::from_hms (0, 0, 9, 0));
        LINE((10.0 / 1080), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK("Some ", "Arial", 20, false, false, false);
-       BLOCK("italics", "Arial", 20, false, true, false);
-       BLOCK(" are here.", "Arial", 20, false, false, false);
+       BLOCK("Some ", "Arial", fs(20), false, false, false);
+       BLOCK("italics", "Arial", fs(20), false, true, false);
+       BLOCK(" are here.", "Arial", fs(20), false, false, false);
        SUB_END();
 
        /* Alignments */
 
        SUB_START (sub::Time::from_hms (0, 0, 9, 230), sub::Time::from_hms (0, 0, 11, 560));
        LINE ((10.0 / 1080), sub::BOTTOM_OF_SCREEN, 0, sub::LEFT_OF_SCREEN);
-       BLOCK("bottom left", "Arial", 20, false, false, false);
+       BLOCK("bottom left", "Arial", fs(20), false, false, false);
        SUB_END ();
 
        SUB_START (sub::Time::from_hms (0, 0, 9, 240), sub::Time::from_hms (0, 0, 11, 560));
        LINE ((10.0 / 1080), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK("bottom centre", "Arial", 20, false, false, false);
+       BLOCK("bottom centre", "Arial", fs(20), false, false, false);
        SUB_END ();
 
        SUB_START (sub::Time::from_hms (0, 0, 9, 250), sub::Time::from_hms (0, 0, 11, 560));
        LINE ((10.0 / 1080), sub::BOTTOM_OF_SCREEN, 0, sub::RIGHT_OF_SCREEN);
-       BLOCK("bottom right", "Arial", 20, false, false, false);
+       BLOCK("bottom right", "Arial", fs(20), false, false, false);
        SUB_END ();
 
        SUB_START (sub::Time::from_hms (0, 0, 9, 260), sub::Time::from_hms (0, 0, 11, 560));
        /* Position is half of a 20pt line (with line spacing) above vertical centre */
-       LINE (-(10.0 * 1.2 / 792), sub::VERTICAL_CENTRE_OF_SCREEN, 0, sub::LEFT_OF_SCREEN);
-       BLOCK("middle left", "Arial", 20, false, false, false);
+       LINE (-vp(10), sub::VERTICAL_CENTRE_OF_SCREEN, 0, sub::LEFT_OF_SCREEN);
+       BLOCK("middle left", "Arial", fs(20), false, false, false);
        SUB_END ();
 
        SUB_START (sub::Time::from_hms (0, 0, 9, 270), sub::Time::from_hms (0, 0, 11, 560));
-       LINE (-(10.0 * 1.2 / 792), sub::VERTICAL_CENTRE_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK("middle centre", "Arial", 20, false, false, false);
+       LINE (-vp(10), sub::VERTICAL_CENTRE_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
+       BLOCK("middle centre", "Arial", fs(20), false, false, false);
        SUB_END ();
 
        SUB_START (sub::Time::from_hms (0, 0, 9, 280), sub::Time::from_hms (0, 0, 11, 560));
-       LINE (-(10.0 * 1.2 / 792), sub::VERTICAL_CENTRE_OF_SCREEN, 0, sub::RIGHT_OF_SCREEN);
-       BLOCK("middle right", "Arial", 20, false, false, false);
+       LINE (-vp(10), sub::VERTICAL_CENTRE_OF_SCREEN, 0, sub::RIGHT_OF_SCREEN);
+       BLOCK("middle right", "Arial", fs(20), false, false, false);
        SUB_END ();
 
        SUB_START (sub::Time::from_hms (0, 0, 9, 290), sub::Time::from_hms (0, 0, 11, 560));
        LINE ((10.0 / 1080), sub::TOP_OF_SCREEN, 0, sub::LEFT_OF_SCREEN);
-       BLOCK("top left", "Arial", 20, false, false, false);
+       BLOCK("top left", "Arial", fs(20), false, false, false);
        SUB_END ();
 
        SUB_START (sub::Time::from_hms (0, 0, 9, 300), sub::Time::from_hms (0, 0, 11, 560));
        LINE ((10.0 / 1080), sub::TOP_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK("top centre", "Arial", 20, false, false, false);
+       BLOCK("top centre", "Arial", fs(20), false, false, false);
        SUB_END ();
 
        SUB_START (sub::Time::from_hms (0, 0, 9, 310), sub::Time::from_hms (0, 0, 11, 560));
        LINE ((10.0 / 1080), sub::TOP_OF_SCREEN, 0, sub::RIGHT_OF_SCREEN);
-       BLOCK("top right", "Arial", 20, false, false, false);
+       BLOCK("top right", "Arial", fs(20), false, false, false);
        SUB_END ();
 
        BOOST_REQUIRE (i == subs.end ());
 }
 
+
 /** Test reading of a file within the libsub-test-private tree which exercises the parser */
 BOOST_AUTO_TEST_CASE (ssa_reader_test4)
 {
@@ -289,39 +316,50 @@ BOOST_AUTO_TEST_CASE (ssa_reader_test4)
 
        BOOST_REQUIRE (i != subs.end ());
 
+       /* Convert a font size in points to a proportional size for this file */
+       auto fs = [](int x) {
+               return static_cast<float>(x) / 288;
+       };
+
+       /* Convert a font size in points to a vertical position for this file */
+       auto vp = [&fs](int x) {
+               return fs(x) * 1.2;
+       };
+
        SUB_START (sub::Time::from_hms (0, 0, 1, 0), sub::Time::from_hms (0, 0, 3, 0));
        /* The first line should be one line (50 points, 1.2 times
           spaced, as a proportion of the total screen height 729
           points) up.
        */
-       LINE ((50.0 * 1.2 / 792), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK ("1st line: This is normal", "Verdana", 50, false, false, false);
-       LINE (0, sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK ("2d line: this is bold", "Verdana", 50, true, false, false);
+       LINE(vp(50), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
+       BLOCK("1st line: This is normal", "Verdana", fs(50), false, false, false);
+       LINE(0, sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
+       BLOCK("2d line: this is bold", "Verdana", fs(50), true, false, false);
        SUB_END ();
 
        SUB_START (sub::Time::from_hms (0, 0, 3, 100), sub::Time::from_hms (0, 0, 5, 100));
-       LINE ((50.0 * 1.2 / 792), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK ("1st line: this is bold", "Verdana", 50, true, false, false);
-       LINE (0, sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK ("2nd line: This is normal", "Verdana", 50, false, false, false);
+       LINE(vp(50), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
+       BLOCK("1st line: this is bold", "Verdana", fs(50), true, false, false);
+       LINE(0, sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
+       BLOCK("2nd line: This is normal", "Verdana", fs(50), false, false, false);
        SUB_END ();
 
        SUB_START (sub::Time::from_hms (0, 0, 5, 200), sub::Time::from_hms (0, 0, 7, 200));
-       LINE ((50.0 * 1.2 / 792), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK ("1st line: this is bold", "Verdana", 50, true, false, false);
-       LINE (0, sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK ("2nd line: this is italics", "Verdana", 50, false, true, false);
+       LINE(vp(50), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
+       BLOCK("1st line: this is bold", "Verdana", fs(50), true, false, false);
+       LINE(0, sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
+       BLOCK("2nd line: this is italics", "Verdana", fs(50), false, true, false);
        SUB_END ();
 
        SUB_START (sub::Time::from_hms (0, 0, 7, 300), sub::Time::from_hms (0, 0, 9, 300));
-       LINE ((50.0 * 1.2 / 792), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK ("1st line: this is italics", "Verdana", 50, false, true, false);
-       LINE (0, sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK ("2nd line: this is bold", "Verdana", 50, true, false, false);
+       LINE(vp(50), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
+       BLOCK("1st line: this is italics", "Verdana", fs(50), false, true, false);
+       LINE(0, sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
+       BLOCK("2nd line: this is bold", "Verdana", fs(50), true, false, false);
        SUB_END ();
 }
 
+
 /** Test reading of a .ass file */
 BOOST_AUTO_TEST_CASE (ssa_reader_test5)
 {
@@ -331,6 +369,16 @@ BOOST_AUTO_TEST_CASE (ssa_reader_test5)
        fclose (f);
        auto subs = sub::collect<vector<sub::Subtitle>> (reader.subtitles());
 
+       /* Convert a font size in points to a proportional size for this file */
+       auto fs = [](int x) {
+               return static_cast<float>(x) / 288;
+       };
+
+       /* Convert a font size in points to a vertical position for this file */
+       auto vp = [&fs](int x) {
+               return fs(x) * 1.2;
+       };
+
        auto i = subs.begin ();
        vector<sub::Line>::iterator j;
        vector<sub::Block>::iterator k;
@@ -342,44 +390,55 @@ BOOST_AUTO_TEST_CASE (ssa_reader_test5)
           spaced, as a proportion of the total screen height 729
           points) up.
        */
-       LINE ((26.0 * 1.2 / 792), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK ("1st subtitle, 1st line", "arial", 26, true, false, false);
-       LINE (0, sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK ("2nd subtitle, 2nd line", "arial", 26, true, false, false);
+       LINE(vp(26), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
+       BLOCK("1st subtitle, 1st line", "arial", fs(26), true, false, false);
+       LINE(0, sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
+       BLOCK("2nd subtitle, 2nd line", "arial", fs(26), true, false, false);
        SUB_END ();
 
        SUB_START (sub::Time::from_hms (0, 0, 3, 100), sub::Time::from_hms (0, 0, 5, 100));
-       LINE ((26.0 * 1.2 / 792), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK ("2nd subtitle, 1st line", "arial", 26, true, false, false);
-       LINE (0, sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK ("2nd subtitle, 2nd line", "arial", 26, true, false, false);
+       LINE(vp(26), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
+       BLOCK("2nd subtitle, 1st line", "arial", fs(26), true, false, false);
+       LINE(0, sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
+       BLOCK("2nd subtitle, 2nd line", "arial", fs(26), true, false, false);
        SUB_END ();
 
        SUB_START (sub::Time::from_hms (0, 0, 5, 200), sub::Time::from_hms (0, 0, 7, 200));
-       LINE ((26.0 * 1.2 / 792), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK ("3rd subtitle, 1st line", "arial", 26, true, false, false);
-       LINE (0, sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK ("3rd subtitle, 2nd line", "arial", 26, true, false, false);
+       LINE(vp(26), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
+       BLOCK("3rd subtitle, 1st line", "arial", fs(26), true, false, false);
+       LINE(0, sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
+       BLOCK("3rd subtitle, 2nd line", "arial", fs(26), true, false, false);
        SUB_END ();
 
        SUB_START (sub::Time::from_hms (0, 0, 7, 300), sub::Time::from_hms (0, 0, 9, 300));
-       LINE ((26.0 * 1.2 / 792), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK ("4th subtitle, 1st line", "arial", 26, true, false, false);
-       LINE (0, sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK ("4th subtitle, 2nd line", "arial", 26, true, false, false);
+       LINE(vp(26), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
+       BLOCK("4th subtitle, 1st line", "arial", fs(26), true, false, false);
+       LINE(0, sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
+       BLOCK("4th subtitle, 2nd line", "arial", fs(26), true, false, false);
        SUB_END ();
 }
 
+
 /** Test reading of another .ass file */
 BOOST_AUTO_TEST_CASE (ssa_reader_test6)
 {
        boost::filesystem::path p = private_test / "DCP-o-matic_test_subs_1.ass";
-       FILE* f = fopen (p.string().c_str(), "r");
+       auto f = fopen (p.string().c_str(), "r");
        BOOST_REQUIRE (f);
        sub::SSAReader reader (f);
        fclose (f);
        auto subs = sub::collect<vector<sub::Subtitle>> (reader.subtitles());
 
+       /* Convert a font size in points to a proportional size for this file */
+       auto fs = [](int x) {
+               return static_cast<float>(x) / 288;
+       };
+
+       /* Convert a font size in points to a vertical position for this file */
+       auto vp = [&fs](int x) {
+               return fs(x) * 1.2;
+       };
+
        auto i = subs.begin ();
        vector<sub::Line>::iterator j;
        vector<sub::Block>::iterator k;
@@ -392,64 +451,64 @@ BOOST_AUTO_TEST_CASE (ssa_reader_test6)
           points) up.  There's also a 10 pixel (with respect to a
           288-pixel-high screen) margin.
        */
-       LINE (((30.0 * 1.2 / 792) + (10.0 / 288.0)), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK ("This line is normal", "Arial", 30, false, false, false);
+       LINE((vp(30) + (10.0 / 288.0)), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
+       BLOCK("This line is normal", "Arial", fs(30), false, false, false);
        LINE ((10.0 / 288.0), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK ("This line is bold", "Arial", 30, true, false, false);
+       BLOCK("This line is bold", "Arial", fs(30), true, false, false);
        SUB_END ();
 
        SUB_START (sub::Time::from_hms (0, 0, 1, 200), sub::Time::from_hms (0, 0, 2, 240));
-       LINE (((30.0 * 1.2 / 792) + (10.0 / 288.0)), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK ("This line is bold", "Arial", 30, true, false, false);
+       LINE((vp(30) + (10.0 / 288.0)), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
+       BLOCK("This line is bold", "Arial", fs(30), true, false, false);
        LINE ((10.0 / 288.0), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK ("This line is normal", "Arial", 30, false, false, false);
+       BLOCK("This line is normal", "Arial", fs(30), false, false, false);
        SUB_END ();
 
        SUB_START (sub::Time::from_hms (0, 0, 2, 300), sub::Time::from_hms (0, 0, 3, 380));
-       LINE (((30.0 * 1.2 / 792) + (10.0 / 288.0)), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK ("This line is bold", "Arial", 30, true, false, false);
+       LINE ((vp(30) + (10.0 / 288.0)), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
+       BLOCK("This line is bold", "Arial", fs(30), true, false, false);
        LINE ((10.0 / 288.0), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK ("This line is italic", "Arial", 30, false, true, false);
+       BLOCK("This line is italic", "Arial", fs(30), false, true, false);
        SUB_END ();
 
        SUB_START (sub::Time::from_hms (0, 0, 3, 400), sub::Time::from_hms (0, 0, 4, 480));
-       LINE (((30.0 * 1.2 / 792) + (10.0 / 288.0)), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK ("This line is italic", "Arial", 30, false, true, false);
+       LINE ((vp(30) + (10.0 / 288.0)), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
+       BLOCK("This line is italic", "Arial", fs(30), false, true, false);
        LINE ((10.0 / 288.0), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK ("This line is bold", "Arial", 30, true, false, false);
+       BLOCK("This line is bold", "Arial", fs(30), true, false, false);
        SUB_END ();
 
        SUB_START (sub::Time::from_hms (0, 0, 4, 510), sub::Time::from_hms (0, 0, 5, 600));
-       LINE (((30.0 * 1.2 / 792) + (10.0 / 288.0)), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK ("Last three words are ", "Arial", 30, false, false, false);
-       BLOCK ("bold AND italic", "Arial", 30, true, true, false);
+       LINE ((vp(30) + (10.0 / 288.0)), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
+       BLOCK("Last three words are ", "Arial", fs(30), false, false, false);
+       BLOCK("bold AND italic", "Arial", fs(30), true, true, false);
        LINE ((10.0 / 288.0), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK ("Last three words are ", "Arial", 30, false, false, false);
-       BLOCK ("italic AND bold", "Arial", 30, true, true, false);
+       BLOCK("Last three words are ", "Arial", fs(30), false, false, false);
+       BLOCK("italic AND bold", "Arial", fs(30), true, true, false);
        SUB_END ();
 
        SUB_START (sub::Time::from_hms (0, 0, 5, 620), sub::Time::from_hms (0, 0, 6, 710));
-       LINE (((30.0 * 1.2 / 792) + (10.0 / 288.0)), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK ("Last three words are ", "Arial", 30, false, false, false);
-       BLOCK ("bold AND italic", "Arial", 30, true, true, false);
+       LINE((vp(30) + (10.0 / 288.0)), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
+       BLOCK("Last three words are ", "Arial", fs(30), false, false, false);
+       BLOCK("bold AND italic", "Arial", fs(30), true, true, false);
        LINE ((10.0 / 288.0), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK ("First three words", "Arial", 30, true, true, false);
-       BLOCK (" are italic AND bold", "Arial", 30, false, false, false);
+       BLOCK("First three words", "Arial", fs(30), true, true, false);
+       BLOCK(" are italic AND bold", "Arial", fs(30), false, false, false);
        SUB_END ();
 
        SUB_START (sub::Time::from_hms (0, 0, 6, 730), sub::Time::from_hms (0, 0, 8, 30));
-       LINE (((30.0 * 1.2 / 792) + (10.0 / 288.0)), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK ("Last three words are ", "Arial", 30, false, false, false);
-       BLOCK ("bold AND italic", "Arial", 30, true, true, false);
+       LINE ((vp(30) + (10.0 / 288.0)), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
+       BLOCK("Last three words are ", "Arial", fs(30), false, false, false);
+       BLOCK("bold AND italic", "Arial", fs(30), true, true, false);
        LINE ((10.0 / 288.0), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK ("This line is normal", "Arial", 30, false, false, false);
+       BLOCK("This line is normal", "Arial", fs(30), false, false, false);
        SUB_END ();
 
        SUB_START (sub::Time::from_hms (0, 0, 8, 90), sub::Time::from_hms (0, 0, 9, 210));
-       LINE (((30.0 * 1.2 / 792) + (10.0 / 288.0)), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK ("Both lines are bold AND italic", "Arial", 30, true, true, false);
-       LINE ((10.0 / 288.0), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK ("Both lines are bold AND italic", "Arial", 30, true, true, false);
+       LINE((vp(30) + (10.0 / 288.0)), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
+       BLOCK("Both lines are bold AND italic", "Arial", fs(30), true, true, false);
+       LINE((10.0 / 288.0), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
+       BLOCK("Both lines are bold AND italic", "Arial", fs(30), true, true, false);
        SUB_END ();
 }
 
@@ -463,6 +522,16 @@ BOOST_AUTO_TEST_CASE (ssa_reader_test7)
        fclose(f);
        auto subs = sub::collect<vector<sub::Subtitle>>(reader.subtitles());
 
+       /* Convert a font size in points to a proportional size for this file */
+       auto fs = [](int x) {
+               return static_cast<float>(x) / 1080;
+       };
+
+       /* Convert a font size in points to a vertical position for this file */
+       auto vp = [&fs](int x) {
+               return fs(x) * 1.2;
+       };
+
        auto i = subs.begin();
        vector<sub::Line>::iterator j;
        vector<sub::Block>::iterator k;
@@ -470,38 +539,38 @@ BOOST_AUTO_TEST_CASE (ssa_reader_test7)
        BOOST_REQUIRE (i != subs.end());
 
        SUB_START(sub::Time::from_hms(0, 0, 1, 0), sub::Time::from_hms(0, 0, 3, 0));
-       LINE(((60.0 * 1.2 / 792) + (100.0 / 1080)), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK("Helvetica Neue 60pt - Default", "Helvetica Neue", 60, false, false, false);
+       LINE((vp(60) + (100.0 / 1080)), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
+       BLOCK("Helvetica Neue 60pt - Default", "Helvetica Neue", fs(60), false, false, false);
        LINE((100.0 / 1080), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK("Bottom 100 pt off edge", "Helvetica Neue", 60, false, false, false);
+       BLOCK("Bottom 100 pt off edge", "Helvetica Neue", fs(60), false, false, false);
        SUB_END();
 
        SUB_START(sub::Time::from_hms(0, 0, 4, 0), sub::Time::from_hms(0, 0, 6, 0));
-       LINE((((30.0 * 1.2) / 792) + (100.0 / 1080)), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK("Helvetica Neue 30pt", "Helvetica Neue", 30, false, false, false);
+       LINE((vp(30) + (100.0 / 1080)), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
+       BLOCK("Helvetica Neue 30pt", "Helvetica Neue", fs(30), false, false, false);
        LINE((100.0 / 1080), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK("Bottom 100pt off edge", "Helvetica Neue", 30, false, false, false);
+       BLOCK("Bottom 100pt off edge", "Helvetica Neue", fs(30), false, false, false);
        SUB_END();
 
        SUB_START(sub::Time::from_hms(0, 0, 7, 0), sub::Time::from_hms(0, 0, 9, 0));
-       LINE((((120.0 * 1.2) / 792) + (100.0 / 1080)), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK("Helvetica Neue 120pt", "Helvetica Neue", 120, false, false, false);
+       LINE((vp(120) + (100.0 / 1080)), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
+       BLOCK("Helvetica Neue 120pt", "Helvetica Neue", fs(120), false, false, false);
        LINE((100.0 / 1080), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK("Bottom 100pt off edge", "Helvetica Neue", 120, false, false, false);
+       BLOCK("Bottom 100pt off edge", "Helvetica Neue", fs(120), false, false, false);
        SUB_END();
 
        SUB_START(sub::Time::from_hms(0, 0, 10, 0), sub::Time::from_hms(0, 0, 12, 0));
        LINE((100.0 / 1080), sub::TOP_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK("Helvetica Neue 60pt", "Helvetica Neue", 60, false, false, false);
-       LINE((((60.0) * 1.2 / 792) + (100.0 / 1080)), sub::TOP_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK("Top Alignment 100pt off edge", "Helvetica Neue", 60, false, false, false);
+       BLOCK("Helvetica Neue 60pt", "Helvetica Neue", fs(60), false, false, false);
+       LINE((vp(60) + (100.0 / 1080)), sub::TOP_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
+       BLOCK("Top Alignment 100pt off edge", "Helvetica Neue", fs(60), false, false, false);
        SUB_END();
 
        SUB_START(sub::Time::from_hms(0, 0, 13, 0), sub::Time::from_hms(0, 0, 15, 0));
-       LINE((-60.0 * 1.2 / 792), sub::VERTICAL_CENTRE_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK("Helvetica Neue 60pt", "Helvetica Neue 60 Center", 60, false, false, false);
+       LINE(vp(-60), sub::VERTICAL_CENTRE_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
+       BLOCK("Helvetica Neue 60pt", "Helvetica Neue 60 Center", fs(60), false, false, false);
        LINE(0, sub::VERTICAL_CENTRE_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK(" Vertical Center Alignment", "Helvetica Neue 60 Center", 60, false, false, false);
+       BLOCK(" Vertical Center Alignment", "Helvetica Neue 60 Center", fs(60), false, false, false);
        SUB_END();
 }
 
@@ -515,6 +584,11 @@ BOOST_AUTO_TEST_CASE (ssa_reader_pos)
        fclose (f);
        auto subs = sub::collect<vector<sub::Subtitle>> (reader.subtitles());
 
+       /* Convert a font size in points to a proportional size for this file */
+       auto fs = [](int x) {
+               return static_cast<float>(x) / 1080;
+       };
+
        auto i = subs.begin ();
        vector<sub::Line>::iterator j;
        vector<sub::Block>::iterator k;
@@ -522,12 +596,13 @@ BOOST_AUTO_TEST_CASE (ssa_reader_pos)
        /* Hello world */
        SUB_START (sub::Time::from_hms (0, 0, 1, 230), sub::Time::from_hms (0, 0, 4, 550));
        LINE ((10.0 / 1080), sub::BOTTOM_OF_SCREEN, 0, sub::HORIZONTAL_CENTRE_OF_SCREEN);
-       BLOCK ("Hello world this is ", "Arial", 20, false, false, false);
+       BLOCK ("Hello world this is ", "Arial", fs(20), false, false, false);
        LINE ((310.0 / 1080), sub::TOP_OF_SCREEN, 400.0 / 1920, sub::LEFT_OF_SCREEN);
-       BLOCK ("positioning.", "Arial", 20, false, false, false);
+       BLOCK ("positioning.", "Arial", fs(20), false, false, false);
        SUB_END();
 }
 
+
 /** Test \fs */
 BOOST_AUTO_TEST_CASE (ssa_reader_fs)
 {
@@ -544,12 +619,13 @@ BOOST_AUTO_TEST_CASE (ssa_reader_fs)
        BOOST_REQUIRE (i != r.end ());
 
        BOOST_CHECK_EQUAL (i->text, "font sizing.");
-       BOOST_CHECK (i->font_size.points());
-       BOOST_CHECK_EQUAL (i->font_size.points().get(), 64);
+       BOOST_REQUIRE(i->font_size.proportional());
+       BOOST_CHECK_CLOSE(i->font_size.proportional().get(), 64.0 / 1080, 0.1);
        ++i;
        BOOST_REQUIRE (i == r.end ());
 }
 
+
 /** Test a valid \c */
 BOOST_AUTO_TEST_CASE (ssa_reader_c)
 {
@@ -567,6 +643,7 @@ BOOST_AUTO_TEST_CASE (ssa_reader_c)
        BOOST_REQUIRE (i == r.end ());
 }
 
+
 /** Test invalid \c */
 BOOST_AUTO_TEST_CASE (ssa_reader_c_bad)
 {