X-Git-Url: https://git.decadent.org.uk/gitweb/?p=videolink.git;a=blobdiff_plain;f=generate_dvd.cpp;h=371894d41edc23abd7ac34abee8337fd52b64711;hp=64079d28ad6c406e6579cc452bb7f1ae1e364ded;hb=HEAD;hpb=07a027ef87333662b3709215025838646ee3d6be

diff --git a/generate_dvd.cpp b/generate_dvd.cpp
index 64079d2..371894d 100644
--- a/generate_dvd.cpp
+++ b/generate_dvd.cpp
@@ -1,6 +1,7 @@
-// Copyright 2005-6 Ben Hutchings <ben@decadent.org.uk>.
+// Copyright 2005-8 Ben Hutchings <ben@decadent.org.uk>.
 // See the file "COPYING" for licence details.
 
+#include <cassert>
 #include <cerrno>
 #include <cstring>
 #include <fstream>
@@ -10,6 +11,10 @@
 #include <sstream>
 #include <stdexcept>
 
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
 #include <gdkmm/pixbuf.h>
 #include <glibmm/miscutils.h>
 #include <glibmm/spawn.h>
@@ -88,9 +93,34 @@ namespace
     double menu_duration_seconds(const video::frame_params & params)
     {
 	return double(menu_duration_frames(params))
-	    * double(params.rate_numer)
-	    / double(params.rate_denom);
+	    / double(params.rate_numer)
+	    * double(params.rate_denom);
     }
+
+    void throw_length_error(const char * limit_type, std::size_t limit)
+    {
+	std::ostringstream oss;
+	oss << "exceeded DVD limit: " << limit_type << " > " << limit;
+	throw std::length_error(oss.str());
+    }
+
+    // dvdauthor uses some menu numbers to represent entry points -
+    // distinct from the actual numbers of the menus assigned as those
+    // entry points - resulting in a practical limit of 119 per
+    // domain.  This seems to be an oddity of the parser that could be
+    // fixed, but for now we'll have to work with it.
+    const unsigned dvdauthor_anonymous_menus_max = dvd::domain_pgcs_max - 8;
+
+    // The current navigation code packs menu and button number into a
+    // single register, so the number of menus is limited to
+    // dvd::reg_s8_button_mult - 1 == 1023.  However temp_file_name()
+    // is limited to 999 numbered files and it seems pointless to
+    // change it to get another 24.
+    // If people really need more we could use separate menu and
+    // button number registers, possibly allowing up to 11900 menus
+    // (the size of the indirect jump tables might become a problem
+    // though).
+    const unsigned menus_max = 999;
 }
 
 dvd_generator::dvd_generator(const video::frame_params & frame_params,
@@ -104,13 +134,8 @@ dvd_generator::pgc_ref dvd_generator::add_menu()
 {
     pgc_ref next_menu(menu_pgc, menus_.size());
 
-    // Check against maximum number of menus.  It appears that no more
-    // than 128 menus are reachable through LinkPGCN instructions, and
-    // dvdauthor uses some menu numbers for special purposes, resulting
-    // in a practical limit of 119 per domain.  We can work around this
-    // later by spreading some menus across titlesets.
-    if (next_menu.index == 119)
-	throw std::runtime_error("No more than 119 menus can be used");
+    if (next_menu.index == menus_max)
+	throw_length_error("number of menus", menus_max);
 
     menus_.resize(next_menu.index + 1);
     return next_menu;
@@ -123,6 +148,10 @@ void dvd_generator::add_menu_entry(unsigned index,
     assert(index < menus_.size());
     assert(target.type == menu_pgc && target.index < menus_.size()
 	   || target.type == title_pgc && target.index < titles_.size());
+
+    if (menus_[index].entries.size() == dvd::menu_buttons_max)
+	throw_length_error("number of buttons", dvd::menu_buttons_max);
+
     menu_entry new_entry = { area, target };
     menus_[index].entries.push_back(new_entry);
 }
@@ -137,12 +166,12 @@ void dvd_generator::generate_menu_vob(unsigned index,
 
     std::string background_name(
 	temp_file_name(temp_dir_, "menu-%3d-back.png", 1 + index));
-    std::cout << "saving " << background_name << std::endl;
+    std::cout << "INFO: Saving " << background_name << std::endl;
     background->save(background_name, "png");
 
     std::string highlights_name(
 	temp_file_name(temp_dir_, "menu-%3d-links.png", 1 + index));
-    std::cout << "saving " << highlights_name << std::endl;
+    std::cout << "INFO: Saving " << highlights_name << std::endl;
     highlights->save(highlights_name, "png");
 
     std::string spumux_name(
@@ -187,11 +216,15 @@ void dvd_generator::generate_menu_vob(unsigned index,
 		}
 	    }
 	}
+	// Pad vertically to even y coordinates since dvdauthor claims
+	// odd values may result in incorrect display.
+	// XXX This may cause overlappping where it wasn't previously
+	// a problem.
 	spumux_file << "      <button"
 	    " x0='" << this_entry.area.left << "'"
-	    " y0='" << this_entry.area.top << "'"
+	    " y0='" << (this_entry.area.top & ~1) << "'"
 	    " x1='" << this_entry.area.right << "'"
-	    " y1='" << this_entry.area.bottom << "'"
+	    " y1='" << ((this_entry.area.bottom + 1) & ~1) << "'"
 	    " left='" << (i == 0 ? button_count : i) << "'"
 	    " right='" << 1 + (i + 1) % button_count << "'"
 	    " up='" << 1 + up_button << "'"
@@ -206,68 +239,53 @@ void dvd_generator::generate_menu_vob(unsigned index,
     if (!spumux_file)
 	throw std::runtime_error("Failed to write control file for spumux");
 
+    std::string output_name(
+	temp_file_name(temp_dir_, "menu-%3d.mpeg", 1 + index));
+
     std::ostringstream command_stream;
-    unsigned frame_count(menu_duration_frames(frame_params_));
     if (encoder_ == mpeg_encoder_ffmpeg)
     {
-	for (unsigned i = 0; i != frame_count; ++i)
-	{
-	    std::string frame_name(background_name);
-	    frame_name.push_back('-');
-	    frame_name.push_back('0' + i / 10);
-	    frame_name.push_back('0' + i % 10);
-	    if (symlink(background_name.c_str(), frame_name.c_str()) != 0)
-		throw std::runtime_error(
-		    std::string("symlink: ").append(std::strerror(errno)));
-	}
 	command_stream <<
 	    "ffmpeg -f image2 -vcodec png"
 	    " -r " << frame_params_.rate_numer <<
 	    "/" << frame_params_.rate_denom <<
-	    " -i " << background_name << "-%02d"
+	    " -loop_input -i " << background_name <<
+	    " -t " << menu_duration_seconds(frame_params_) <<
 	    " -target " << frame_params_.common_name <<  "-dvd"
-	    " -vcodec mpeg2video -aspect 4:3 -an -y /dev/stdout";
+	    " -aspect 4:3 -an -y /dev/stdout";
     }
     else
     {
-	assert(encoder_ == mpeg_encoder_mjpegtools_old
-	       || encoder_ == mpeg_encoder_mjpegtools_new);
+	assert(encoder_ == mpeg_encoder_mjpegtools);
 	command_stream
 	    << "pngtopnm " << background_name
-	    << " | ppmtoy4m -v0 -n" << frame_count << " -F"
-	    << frame_params_.rate_numer << ":" << frame_params_.rate_denom
+	    << " | ppmtoy4m -v0 -n" << menu_duration_frames(frame_params_)
+	    << " -F" << frame_params_.rate_numer << ":" << frame_params_.rate_denom
 	    << " -A" << frame_params_.pixel_ratio_width
 	    << ":" << frame_params_.pixel_ratio_height
-	    << " -Ip ";
-	// The chroma subsampling keywords changed between
-	// versions 1.6.2 and 1.8 of mjpegtools.  There is no
-	// keyword that works with both.
-	if (encoder_ == mpeg_encoder_mjpegtools_old)
-	    command_stream << "-S420_mpeg2";
-	else
-	    command_stream << "-S420mpeg2";
-	command_stream <<
+	    << " -Ip -S420mpeg2"
 	    " | mpeg2enc -v0 -f8 -a2 -o/dev/stdout"
 	    " | mplex -v0 -f8 -o/dev/stdout /dev/stdin";
     }
     command_stream
-	<< " | spumux -v0 -mdvd " << spumux_name
-	<< " > " << temp_file_name(temp_dir_, "menu-%3d.mpeg", 1 + index);
+	<< " | spumux -v0 -mdvd " << spumux_name << " > " << output_name;
     std::string command(command_stream.str());
     const char * argv[] = {
 	"/bin/sh", "-c", command.c_str(), 0
     };
-    std::cout << "running " << command << std::endl;
+    std::cout << "INFO: Running " << command << std::endl;
     int command_result;
     Glib::spawn_sync(".",
 		     Glib::ArrayHandle<std::string>(
 			 argv, sizeof(argv)/sizeof(argv[0]),
 			 Glib::OWNERSHIP_NONE),
 		     Glib::SPAWN_STDOUT_TO_DEV_NULL,
-		     SigC::Slot0<void>(),
+		     sigc::slot<void>(),
 		     0, 0,
 		     &command_result);
-    if (command_result != 0)
+    struct stat stat_buf;
+    if (command_result != 0 || stat(output_name.c_str(), &stat_buf) != 0
+	|| stat_buf.st_size == 0)
 	throw std::runtime_error("spumux pipeline failed");
 }
 
@@ -276,8 +294,8 @@ dvd_generator::pgc_ref dvd_generator::add_title(vob_list & content)
     pgc_ref next_title(title_pgc, titles_.size());
 
     // Check against maximum number of titles.
-    if (next_title.index == 99)
-	throw std::runtime_error("No more than 99 titles can be used");
+    if (next_title.index == dvd::titles_max)
+	throw_length_error("number of titles", dvd::titles_max);
 
     titles_.resize(next_title.index + 1);
     titles_[next_title.index].swap(content);
@@ -286,257 +304,390 @@ dvd_generator::pgc_ref dvd_generator::add_title(vob_list & content)
 
 void dvd_generator::generate(const std::string & output_dir) const
 {
+    // This function uses a mixture of 0-based and 1-based numbering,
+    // due to the differing conventions of the language and the DVD
+    // format.  Variable names ending in "_index" indicate 0-based
+    // indices and variable names ending in "_num" indicate 1-based
+    // numbers.
+
     std::string name(temp_file_name(temp_dir_, "videolink.dvdauthor"));
     std::ofstream file(name.c_str());
+    file << "<dvdauthor>\n";
 
     // We generate code that uses registers in the following way:
     //
-    // g0:     scratch
-    // g1:     target menu location
-    // g2:     source/return menu location for title
-    // g3:     target chapter number
-    //
-    // All locations are divided into two bitfields: the least
-    // significant 10 bits are a page/menu number and the most
-    // significant 6 bits are a link/button number, and numbering
-    // starts at 1, not 0.  This is done for compatibility with
-    // the encoding of the s8 (button) register.
-    //
-    static const int button_mult = dvd::reg_s8_button_mult;
-    static const int menu_mask = button_mult - 1;
-    static const int button_mask = (1 << dvd::reg_bits) - button_mult;
-
-    file <<
-	"<dvdauthor>\n"
-	"  <vmgm>\n"
-	"    <menus>\n";
-	    
-    for (unsigned menu_index = 0; menu_index != menus_.size(); ++menu_index)
+    // g0: Scratch.
+    // g1: Target location when jumping between menus.  Top 6 bits are
+    //     the button number (like s8) and bottom 10 bits are the menu
+    //     number.  This is used for selecting the appropriate button
+    //     when entering a menu, for completing indirect jumps between
+    //     domains, and for jumping to the correct menu after exiting a
+    //     title.  This is set to 0 in the pre-routine of the target
+    //     menu.
+    // g2: Current location in menus.  This is used for jumping to the
+    //     correct menu when the player exits a title.
+    // g3: Target chapter number plus 1 when jumping to a title.
+    //     This is used to jump to the correct chapter and to
+    //     distinguish between indirect jumps to menus and titles.
+    //     This is set to 0 in the pre-routine of the target title.
+    // g4: Source menu location used to jump to a title.  This is
+    //     compared with g2 to determine whether to increment the
+    //     button number if the title is played to the end.
+
+    static const unsigned button_mult = dvd::reg_s8_button_mult;
+    static const unsigned menu_mask = button_mult - 1;
+    static const unsigned button_mask = (1U << dvd::reg_bits) - button_mult;
+
+    // Iterate over VMGM and titlesets.  For these purposes, we
+    // consider the VMGM to be titleset 0.
+
+    // We need a titleset for each title, and we may also need titlesets to
+    // hold extra menus if we have too many for the VMGM.
+    // Also, we need at least one titleset.
+    const unsigned titleset_end = std::max<unsigned>(
+	    1U + std::max<unsigned>(1U, titles_.size()),
+	    (menus_.size() + dvdauthor_anonymous_menus_max - 1)
+		 / dvdauthor_anonymous_menus_max);
+
+    for (unsigned titleset_num = 0;
+	 titleset_num != titleset_end;
+	 ++titleset_num)
     {
-	const menu & this_menu = menus_[menu_index];
-
-	if (menu_index == 0)
+	const char * const outer_element_name =
+	    titleset_num == 0 ? "vmgm" : "titleset";
+	const bool have_real_title =
+	    titleset_num != 0 && titleset_num <= titles_.size();
+	const bool have_real_menus =
+	    titleset_num * dvdauthor_anonymous_menus_max < menus_.size();
+
+	file << "  <" << outer_element_name << ">\n" <<
+	     "    <menus>\n"
+	     "      <video format='" << frame_params_.common_name << "'/>\n";
+
+	const unsigned menu_begin = titleset_num * dvdauthor_anonymous_menus_max;
+	const unsigned menu_end =
+	    have_real_menus
+	    ? std::min<unsigned>(
+		(titleset_num + 1) * dvdauthor_anonymous_menus_max,
+		menus_.size())
+	    : menu_begin + 1;
+
+	for (unsigned menu_index = menu_begin;
+	     menu_index != menu_end;
+	     ++menu_index)
 	{
-	    // This is the first (title) menu, displayed when the
-	    // disc is first played.
-	    file <<
-		"      <pgc entry='title'>\n"
-		"        <pre>\n"
-		// Set a default target location if none is set.
-		// This covers first play and use of the "top menu"
-		// button.
-		"          if (g1 eq 0)\n"
-		"            g1 = " << 1 + button_mult << ";\n";
-	}
-	else
-	{
-	    file <<
-		"      <pgc>\n"
-		"        <pre>\n";
-	}
+	    // There are various cases in which menus may be called:
+	    //
+	    // 1. The user follows a direct link to the menu.
+	    // 2. The user follows an indirect link to some other menu
+	    //    and that goes via this menu.  This is distinguished
+            //    from case 1 by the value of g1.  We must jump to or
+	    //    at least toward the other menu.
+	    // 3. The title menu is called when the disc is first
+	    //    played or the user presses the "top menu" button.
+	    //    This is distinguished from cases 2 and 3 by g1 == 0.
+	    //    We make this look like case 1.
+	    // 4. The root menu of a titleset is called when the user
+	    //    follows an indirect link to the title.  This is
+	    //    distinguished from all other cases by g3 != 0.  We
+	    //    must jump to the title.
+	    // 5. The root menu of a titleset is called when the title
+	    //    ends or the user presses the "menu" button during
+	    //    the title.  This is distinguished from cases 1, 2
+	    //    and 4 by g1 == 0 and g3 == 0.  We must jump to the
+	    //    latest menu (which can turn into case 1 or 2).
+	    //
+	    // Cases 3 and 5 do not apply to the same menus so they
+	    // do not need to be distinguished.
+
+	    if (menu_index == 0)
+	    {
+		// Title menu.
+		file <<
+		    "      <pgc entry='title'>\n"
+		    "        <pre>\n"
+		    "          if (g1 eq 0)\n" // case 3
+		    "            g1 = " << 1 + button_mult << ";\n";
+	    }
+	    else if (menu_index == titleset_num * dvdauthor_anonymous_menus_max)
+	    {
+		// Root menu.
+ 		file <<
+		    "      <pgc entry='root'>\n"
+		    "        <pre>\n";
+		if (have_real_title)
+		{
+		    file <<
+			"          if (g3 ne 0)\n" // case 4
+			"            jump title 1;\n"
+			"          if (g1 eq 0) {\n" // case 5
+			"            g1 = g2;\n"
+			"            jump vmgm menu entry title;\n"
+			"          }\n";
+		}
+	    }
+	    else
+	    {
+		// Some other menu.
+		file <<
+		    "      <pgc>\n"
+		    "        <pre>\n";
+	    }
 
-	// When a title finishes or the user presses the "menu"
-	// button, this always jumps to the titleset's root menu.
-	// We want to return the user to the last menu they used.
-	// So we arrange for each titleset's root menu to return
-	// to the vmgm title menu and then dispatch from there to
-	// whatever the correct menu is.  We determine the correct
-	// menu by looking at the menu part of g1.
-
-	file << "          g0 = g1 &amp; " << menu_mask << ";\n";
-
-	// There is a limit of 128 VM instructions in each PGC.
-	// Therefore in each menu's <pre> section we generate
-	// jumps to menus with numbers greater by 512, 256, 128,
-	// ..., 1 where (a) such a menu exists, (b) this menu
-	// number is divisible by twice that increment and (c) the
-	// correct menu is that or a later menu.  Thus each menu
-	// has at most 10 such conditional jumps and is reachable
-	// by at most 10 jumps from the title menu.  This chain of
-	// jumps might take too long on some players; this has yet
-	// to be investigated.
-	    
-	for (std::size_t menu_incr = (menu_mask + 1) / 2;
-	     menu_incr != 0;
-	     menu_incr /= 2)
-	{
-	    if (menu_index + menu_incr < menus_.size()
-		&& (menu_index & (menu_incr * 2 - 1)) == 0)
+	    if (!have_real_menus)
 	    {
+		// This is a root menu only reachable from the title.
 		file <<
-		    "          if (g0 ge " << 1 + menu_index + menu_incr
-					   << ")\n"
-		    "            jump menu " << 1 + menu_index + menu_incr
-					   << ";\n";
+		    "        </pre>\n"
+		    "      </pgc>\n";
+		continue;
 	    }
-	}
 
-	file <<
+	    const menu & this_menu = menus_[menu_index];
+
+	    // Detect and handle case 2.
+	    //
+	    // There is a limit of 128 VM instructions in each PGC.
+	    // Also, we can't jump to an arbitrary menu in another
+	    // domain.  Finally, we can't do computed jumps.
+	    // Therefore we statically expand and distribute a binary
+	    // search across the menus, resulting in a code size of
+	    // O(log(menu_count)) in each menu.  In practice there are
+	    // at most 11 conditional jumps needed in any menu.
+	    //
+	    // The initial bounds of the binary search are strange
+	    // because we must ensure that any jump between titlesets
+	    // is to the first menu of the titleset, marked as the
+	    // root entry.
+
+	    // Mask target location to get the target menu.
+	    file << "          g0 = g1 &amp; " << menu_mask << ";\n";
+
+	    for (unsigned
+		     bottom = 0,
+		     top = 16 * dvdauthor_anonymous_menus_max;
+		 top - bottom > 1;)
+	    {
+		unsigned middle = (bottom + top) / 2;
+		if (menu_index == bottom && middle < menus_.size())
+		{
+		    file << "          if (g0 ge " << 1 + middle << ")\n"
+			 << "            jump ";
+		    unsigned target_titleset_num =
+			middle / dvdauthor_anonymous_menus_max;
+		    if (target_titleset_num != titleset_num)
+		    {
+			assert(middle % dvdauthor_anonymous_menus_max == 0);
+			file << "titleset " << target_titleset_num
+			     << " menu entry root";
+		    }
+		    else
+		    {
+			file << "menu "
+			     << 1 + middle % dvdauthor_anonymous_menus_max;
+		    }
+		    file << ";\n";
+		}
+		if (menu_index >= middle)
+		    bottom = middle;
+		else
+		    top = middle;
+	    }
+
+	    // Case 1.
+
 	    // Highlight the appropriate button.
-	    "          s8 = g1 &amp; " << button_mask << ";\n"
-	    // Forget the link target.  If we don't do this, pressing
-	    // the "top menu" button will result in jumping back to
-	    // this same menu!
-	    "          g1 = 0;\n"
-	    "        </pre>\n"
-	    "        <vob file='"
-	     << temp_file_name(temp_dir_, "menu-%3d.mpeg", 1 + menu_index)
-	     << "'>\n"
-	    // Define a cell covering the whole menu and set a still
-	    // time at the end of that, since it seems all players
-	    // support that but some ignore a still time set on a PGC.
-	    "          <cell start='0' end='"
-	     << std::fixed << std::setprecision(4)
-	     << menu_duration_seconds(frame_params_) << "'"
-	    " chapter='yes' pause='inf'/>\n"
-	    "        </vob>\n";
-
-	for (unsigned button_index = 0;
-	     button_index != this_menu.entries.size();
-	     ++button_index)
-	{
-	    const pgc_ref & target = this_menu.entries[button_index].target;
+	    file << "          s8 = g1 &amp; " << button_mask << ";\n";
 
-	    file << "        <button> ";
+	    // Copy the target location to the current location and
+	    // then clear the target location so that the title menu
+	    // can distinguish cases 2 and 3.
+	    file <<
+		"          g2 = g1;\n"
+		"          g1 = 0;\n";
 
-	    if (target.type == menu_pgc)
+	    file <<
+		"        </pre>\n"
+		"        <vob file='"
+		 << temp_file_name(temp_dir_, "menu-%3d.mpeg",
+				   1 + menu_index)
+		 << "'>\n"
+		// Define a cell covering the whole menu and set a still
+		// time at the end of that, since it seems all players
+		// support that but some ignore a still time set on a PGC.
+		"          <cell start='0' end='"
+		 << std::fixed << std::setprecision(4)
+		 << menu_duration_seconds(frame_params_) << "'"
+		" chapter='yes' pause='inf'/>\n"
+		"        </vob>\n";
+
+	    for (unsigned button_index = 0;
+		 button_index != this_menu.entries.size();
+		 ++button_index)
 	    {
-		unsigned target_button_num;
+		const pgc_ref & target =
+		    this_menu.entries[button_index].target;
 
-		if (target.sub_index)
+		file << "        <button> ";
+
+		if (target.type == menu_pgc)
 		{
-		    target_button_num = target.sub_index;
+		    unsigned target_button_num;
+
+		    if (target.sub_index)
+		    {
+			target_button_num = target.sub_index;
+		    }
+		    else
+		    {
+			// Look for a button on the new menu that links
+			// back to this one.  If there is one, set that to
+			// be the highlighted button; otherwise, use the
+			// first button.
+			const std::vector<menu_entry> & target_menu_entries =
+			    menus_[target.index].entries;
+			pgc_ref this_pgc(menu_pgc, menu_index);
+			target_button_num = target_menu_entries.size();
+			while (target_button_num != 1
+			       && (target_menu_entries[target_button_num - 1].target
+				   != this_pgc))
+			    --target_button_num;
+		    }
+			 
+		    // Set new menu location.
+		    file << "g1 = "
+			 << (1 + target.index + target_button_num * button_mult)
+			 << "; ";
+		    // Jump to the target menu.
+		    unsigned target_titleset_num =
+			target.index / dvdauthor_anonymous_menus_max;
+		    if (target_titleset_num == titleset_num)
+			file << "jump menu "
+			     << 1 + (target.index
+				     % dvdauthor_anonymous_menus_max)
+			     << "; ";
+		    else if (target_titleset_num == 0)
+			file << "jump vmgm menu entry title; ";
+		    else
+			file << "jump titleset " << target_titleset_num
+			     << " menu entry root; ";
 		}
 		else
 		{
-		    // Look for a button on the new menu that links
-		    // back to this one.  If there is one, set that to
-		    // be the highlighted button; otherwise, use the
-		    // first button.
-		    const std::vector<menu_entry> & target_menu_entries =
-			menus_[target.index].entries;
-		    pgc_ref this_pgc(menu_pgc, menu_index);
-		    target_button_num = target_menu_entries.size();
-		    while (target_button_num != 1
-			   && (target_menu_entries[target_button_num - 1].target
-			       != this_pgc))
-			--target_button_num;
+		    assert(target.type == title_pgc);
+
+		    // Record current menu location and set target chapter
+		    // number.
+		    file <<
+			"g2 = " << (1 + menu_index
+				    + (1 + button_index) * button_mult) << "; "
+			"g3 = " << 1 + target.sub_index << "; ";
+		    // Jump to the target title, possibly via its titleset's
+		    // root menu.
+		    unsigned target_titleset_num = 1 + target.index;
+		    if (titleset_num == 0)
+			file << "jump title " << target_titleset_num << "; ";
+		    else if (target_titleset_num == titleset_num)
+			file << "jump title 1; ";
+		    else
+			file << "jump titleset " << target_titleset_num
+			     << " menu entry root; ";
 		}
-			 
-		file <<
-		    // Set new menu location.
-		    "g1 = " << (1 + target.index
-				+ target_button_num * button_mult) << "; "
-		    // Jump to the target menu.
-		    "jump menu " << 1 + target.index << "; ";
-	    }
-	    else
-	    {
-		assert(target.type == title_pgc);
 
-		file <<
-		    // Record current menu location.
-		    "g2 = " << (1 + menu_index
-				+ (1 + button_index) * button_mult) << "; "
-		    // Set target chapter number.
-		    "g3 = " << target.sub_index << "; "
-		    // Jump to the target title.
-		    "jump title " << 1 + target.index << "; ";
+		file <<  "</button>\n";
 	    }
 
-	    file <<  "</button>\n";
+	    file <<
+		"      </pgc>\n";
 	}
 
-	file <<
-	    "      </pgc>\n";
-    }
+	file << "    </menus>\n";
 
-    file <<
-	"    </menus>\n"
- 	"  </vmgm>\n";
- 
-    // Generate a titleset for each title.  This appears to make
-    // jumping to titles a whole lot simpler (but limits us to 99
-    // titles).
-    for (unsigned title_index = 0;
- 	 title_index != titles_.size();
- 	 ++title_index)
-    {
- 	file <<
-	    "  <titleset>\n"
-	    // Generate a dummy menu so that the "menu" button will
-	    // work.  This returns to the source menu via the title
-	    // menu.
-	    "    <menus>\n"
-	    "      <pgc entry='root'>\n"
-	    "        <pre> g1 = g2; jump vmgm menu; </pre>\n"
-	    "      </pgc>\n"
-	    "    </menus>\n"
-	    "    <titles>\n"
-	    "      <pgc>\n"
-	    "        <pre>\n";
-
-	// Count chapters in the title.
-	unsigned n_chapters = 0;
-	for (vob_list::const_iterator
-		 it = titles_[title_index].begin(),
-		 end = titles_[title_index].end();
-	     it != end;
-	     ++it)
+	if (have_real_title)
 	{
-	    // Chapter start times may be specified in the "chapters"
-	    // attribute as a comma-separated list.  If this is not
-	    // specified then the beginning of each file starts a new
-	    // chapter.  Thus the number of chapters in each file is
-	    // the number of commas in the chapter attribute, plus 1.
-	    ++n_chapters;
-	    std::size_t pos = 0;
-	    while ((pos = it->chapters.find(',', pos)) != std::string::npos)
+	    file <<
+		"    <titles>\n"
+		"      <video format='" << frame_params_.common_name << "'/>\n"
+		"      <pgc>\n";
+
+	    file << "        <pre>\n";
+
+	    // Count chapters in the title.
+	    unsigned n_chapters = 0;
+	    for (vob_list::const_iterator
+		     it = titles_[titleset_num - 1].begin(),
+		     end = titles_[titleset_num - 1].end();
+		 it != end;
+		 ++it)
 	    {
+		// Chapter start times may be specified in the "chapters"
+		// attribute as a comma-separated list.  If this is not
+		// specified then the beginning of each file starts a new
+		// chapter.  Thus the number of chapters in each file is
+		// the number of commas in the chapter attribute, plus 1.
 		++n_chapters;
-		++pos;
+		std::size_t pos = 0;
+		while ((pos = it->chapters.find(',', pos)) != std::string::npos)
+		{
+		    ++n_chapters;
+		    ++pos;
+		}
 	    }
-	}
 
-	// Generate jump "table" for chapters.
-	for (unsigned chapter_num = 1;
-	     chapter_num <= n_chapters;
-	     ++chapter_num)
-	    file <<
-		"          if (g3 == " << chapter_num << ")\n"
-		"            jump chapter " << chapter_num << ";\n";
+	    // Move the chapter number to scratch so the root menu can
+	    // distinguish cases 4 and 5.
+	    file << "          g0 = g3; g3 = 0;\n";
 
-	file <<
-	    "        </pre>\n";
+	    // Copy the latest menu location for use by the post-routine.
+	    file << "          g4 = g2;\n";
 
-	for (vob_list::const_iterator
-		 it = titles_[title_index].begin(),
-		 end = titles_[title_index].end();
-	     it != end;
-	     ++it)
+	    // Jump to the correct chapter.
+	    for (unsigned chapter_num = 1;
+		 chapter_num <= n_chapters;
+		 ++chapter_num)
+		file <<
+		    "          if (g0 eq " << 1 + chapter_num << ")\n"
+		    "            jump chapter " << chapter_num << ";\n";
+
+	    file << "        </pre>\n";
+
+	    for (vob_list::const_iterator
+		     it = titles_[titleset_num - 1].begin(),
+		     end = titles_[titleset_num - 1].end();
+		 it != end;
+		 ++it)
+	    {
+		file << "        <vob file='" << xml_escape(it->file) << "'";
+		if (!it->chapters.empty())
+		    file << " chapters='" << xml_escape(it->chapters) << "'";
+		if (!it->pause.empty())
+		    file << " pause='" << xml_escape(it->pause) << "'";
+		file << "/>\n";
+	    }
+
+	    // If the user has not exited to the menus and then
+	    // resumed the title, set the latest menu location to be
+	    // the button after the one that linked to this title.
+	    // In any case, return to the (root) menu which will
+	    // then jump to the correct menu.
+	    file <<
+		"        <post>\n"
+		"          if (g2 eq g4)\n"
+		"            g2 = g2 + " << button_mult << ";\n"
+		"          call menu;\n"
+		"        </post>\n"
+		"      </pgc>\n"
+		"    </titles>\n";
+	}
+	else if (titleset_num != 0) // && !have_real_title
 	{
-	    file << "        <vob file='" << xml_escape(it->file) << "'";
-	    if (!it->chapters.empty())
-		file << " chapters='" << xml_escape(it->chapters) << "'";
-	    if (!it->pause.empty())
-		file << " pause='" << xml_escape(it->pause) << "'";
-	    file << "/>\n";
+	    file << "    <titles><pgc/></titles>\n";
 	}
 
-	file <<
-	    "        <post>\n"
-	    // Return to the source menu, but highlight the next button.
-	    "          g2 = g2 + " << button_mult << ";\n"
-	    "          call menu;\n"
-	    "        </post>\n"
-	    "      </pgc>\n"
-	    "    </titles>\n"
-	    "  </titleset>\n";
+	file << "  </" << outer_element_name << ">\n";
     }
 
-    file <<
-	"</dvdauthor>\n";
-
+    file << "</dvdauthor>\n";
     file.close();
 
     {
@@ -553,7 +704,7 @@ void dvd_generator::generate(const std::string & output_dir) const
 			     Glib::OWNERSHIP_NONE),
 			 Glib::SPAWN_SEARCH_PATH
 			 | Glib::SPAWN_STDOUT_TO_DEV_NULL,
-			 SigC::Slot0<void>(),
+			 sigc::slot<void>(),
 			 0, 0,
 			 &command_result);
 	if (command_result != 0)