Failure to recognize Tx3g subtitle streams, for import from MP4 files
When I attempt to remux or pull in a Tx3g subtitle stream from an MP4 video, MKVToolNix does not recognize the stream.
The stream is recognized in ffmpeg and Subler and I can manually extract to an SRT. ffmpeg shows a stream e.g.: Stream #0:2(eng): Subtitle: mov_text (tx3g / 0x67337874), 682x57, 0 kb/s (default) but dragging the .mp4 file to the MKVToolNix Source files window does not display this subtitle stream in the Tracks,Chapters and Tags
I've encountered this problem for a long time, and have just updated to v52.0.0 on MacOS and still see the problem. I've attached a brief sample video that has a Tx3g subtitle stream which v56.0.0 does not recognize for import to an MKV file. tx3g_subtitle_import_testcase