ttmlrender / ttmlparser: mp4-container: no subtitles rendered after seek (network source)
Description
When playing a mp4-Container with TTML subtitles from http-location, subtitles disappear after seek.
To reproduce
- copy the attached streams to network server (I'm using a "actual" Apache at Windows 10)
- run the command "
export GST_TTML_AUTOPLUG=1 && gst-play-1.0 http://192.168.0.252/media/.../1280x720-h264-ttml-de.mp4
" - subtitles are visible
- Use "right"-Key to jump 10s foreward
- subtitles disappear -> error
Reproduced with GStreamer 1.16, 1.20.3 (Ubuntu 22.04.1 LTS) (and with other local GStreamer installation)
Additional Info:
- The problem occurs
- with TTML subtitles from network source.
- with playbin2 and playbin3 (
gst-play-1.0 --use-playbin3 ...
)
- The problem does not occur
- MP4 container with SRT subtitles (1280x720-h264-srt-de.mp4)
- MP4 container with TTML subtitles from local file source (
gst-play-1.0 file://.../1280x720-h264-ttml-de.mp4
)
Attachments:
- test streams:
- pipelines:
I'm not sure if this is really a TTML problem. The difference between http an file is also pull- vs push-mode in upstream parts of pipeline (source -> qtdemux). So also may be typefinder or qtdemux is involved.