Added support for exporting mp4 chapter marks

The mp4 file format supports chapter marks using the so called
mp4chaps format to enable chapter wise navigation in an mp4 file. The
format is like

hh:mm:ss.sss Chapter Title

This commit adds the ability to export those kind of chapter marks
along with TOC and CUE marks. The filename extension for the chapter
mark file is "chapters.txt". The format specification description is
"MP4ch".

1 files changed, 50 insertions, 4 deletions

diff --git a/libs/ardour/export_handler.cc b/libs/ardour/export_handler.cc
index b44c46e549..33e19d663f 100644
--- a/libs/ardour/export_handler.cc
+++ b/libs/ardour/export_handler.cc
@@ -305,6 +305,10 @@ ExportHandler::finish_timespan ()
 			export_cd_marker_file (current_timespan, fmt, filename, CDMarkerTOC);
 		}
 
+		if (fmt->with_mp4chaps()) {
+			export_cd_marker_file (current_timespan, fmt, filename, MP4Chaps);
+		}
+
 		if (fmt->tag()) {
 			AudiofileTagger::tag_file(filename, *SessionMetadata::Metadata());
 		}
@@ -403,6 +407,11 @@ ExportHandler::export_cd_marker_file (ExportTimespanPtr timespan, ExportFormatSp
 			track_func = &ExportHandler::write_track_info_cue;
 			index_func = &ExportHandler::write_index_info_cue;
 			break;
+		case MP4Chaps:
+			header_func = &ExportHandler::write_mp4ch_header;
+			track_func = &ExportHandler::write_track_info_mp4ch;
+			index_func = &ExportHandler::write_index_info_mp4ch;
+			break;
 		default:
 			return;
 		}
@@ -500,17 +509,19 @@ ExportHandler::export_cd_marker_file (ExportTimespanPtr timespan, ExportFormatSp
 string
 ExportHandler::get_cd_marker_filename(std::string filename, CDMarkerFormat format)
 {
-	/* do not strip file suffix because there may be more than one format, 
+	/* do not strip file suffix because there may be more than one format,
 	   and we do not want the CD marker file from one format to overwrite
 	   another (e.g. foo.wav.cue > foo.aiff.cue)
 	*/
 
 	switch (format) {
-	  case CDMarkerTOC:
+	case CDMarkerTOC:
 		return filename + ".toc";
-	  case CDMarkerCUE:
+	case CDMarkerCUE:
 		return filename + ".cue";
-	  default:
+	case MP4Chaps:
+		return filename + ".chapters.txt";
+	default:
 		return filename + ".marker"; // Should not be reached when actually creating a file
 	}
 }
@@ -590,6 +601,11 @@ ExportHandler::write_toc_header (CDMarkerStatus & status)
 }
 
 void
+ExportHandler::write_mp4ch_header (CDMarkerStatus & status)
+{
+}
+
+void
 ExportHandler::write_track_info_cue (CDMarkerStatus & status)
 {
 	gchar buf[18];
@@ -693,6 +709,14 @@ ExportHandler::write_track_info_toc (CDMarkerStatus & status)
 	status.out << "START" << buf << endl;
 }
 
+void ExportHandler::write_track_info_mp4ch (CDMarkerStatus & status)
+{
+	gchar buf[18];
+
+	frames_to_chapter_marks_string(buf, status.track_start_frame);
+	status.out << buf << " " << status.marker->name() << endl;
+}
+
 void
 ExportHandler::write_index_info_cue (CDMarkerStatus & status)
 {
@@ -716,6 +740,11 @@ ExportHandler::write_index_info_toc (CDMarkerStatus & status)
 }
 
 void
+ExportHandler::write_index_info_mp4ch (CDMarkerStatus & status)
+{
+}
+
+void
 ExportHandler::frames_to_cd_frames_string (char* buf, framepos_t when)
 {
 	framecnt_t remainder;
@@ -730,6 +759,23 @@ ExportHandler::frames_to_cd_frames_string (char* buf, framepos_t when)
 	sprintf (buf, " %02d:%02d:%02d", mins, secs, frames);
 }
 
+void
+ExportHandler::frames_to_chapter_marks_string (char* buf, framepos_t when)
+{
+	framecnt_t remainder;
+	framecnt_t fr = session.nominal_frame_rate();
+	int hours, mins, secs, msecs;
+
+	hours = when / (3600 * fr);
+	remainder = when - (hours * 3600 * fr);
+	mins = remainder / (60 * fr);
+	remainder -= mins * 60 * fr;
+	secs = remainder / fr;
+	remainder -= secs * fr;
+	msecs = (remainder * 1000) / fr;
+	sprintf (buf, "%02d:%02d:%02d.%03d", hours, mins, secs, msecs);
+}
+
 std::string
 ExportHandler::toc_escape_cdtext (const std::string& txt)
 {