Subtitles in MKV recording have no duration set
When recording with the MKV profile, the subtitle track's blocks are not given a duration. Per https://www.matroska.org/technical/specs/subtitles/srt.html, it seems duration should be set via the
(I originally posted this in #3996-1 but figured it better to create a separate issue.)
Updated by Jaroslav Kysela about 2 years ago
Thinking more about this - it's not an easy one. The teletext really ends the subtitles with the zero text, so we don't know the duration when the subtitle is started and if we wait to the end mark (empty text), the subtitle will be muxed to the matroska too late (after video/audio). We can do this with more queuing at the muxer side, but it will cost more latency.