Handle embedded subtitles
Some video files (mostly using the matroska container, *.mkv) have embedded subtitles in them. Currently Kdenlive ignores them. This can be implemented in three steps:
-
When adding an mkv file, we should check if it has subtitle stream(s) and display this info in the clip properties panel. (this probably needs to be done through FFmpeg since MLT doesn't check subtitle streams. -
Add an option in the clip properties panel to display or hide these subtitles (adding an avfilter.subtitles filter referencing the video file will make it work). -
When using the automatic subtitle stream dialog in timeline and the clip is selected, offer an option to extract the subtitles to the subtitles track.
Attached is a sample mkv file (color clip with subtitle stream). embeded-subtitles.mkv