The goal of this project is to convert an EBU STL (Tech 3264) binary file and produce equivalent web centric captioning formats.
Output formats supported:
- TTML text captions using regions for vertical placement and in-line text colour styling with spans
- WebVTT with vertical placement and colour support using cue::color styling
The script/convert_stl.sh uses bin/jar/STL2TTML.jar with groovy dependencies to run the application. All that is
required is a Java 8+ runtime in the path.
STL2TTML Options:
-f | -file STL file to process
-o | -offset number of seconds to add to the STL timing
-t | -ttml Create TTML file
-v | -vtt Create VTT file
-ns | -no-vtt-styling Disable all VTT Styling
-l | -log-level Logging level > 0 to produce output
-s | -safe-area VTT Vertical safe area precentage 0 .. 50
-z | -zero-timecode Remove any non-zero timecode reference from the STL captions
The safe-area option prevents the caption text from being rendered on the very top and bottom of the player area. The default value is set at 5% but can be disabled by setting -s 0 on the command line.
The zero-timecode option removes timecode offsets that are multiples of 1 hour added to the first valid timecode (firstInCue from the GsiBlock). Any text blocks before the firstInCue position are ignored when using this option flag.