current imx6 bsp, not only ltib but also yocto couldn't support subtitle.
now we have two solution to support subtitle on yocto,
1)one is extract the subtitle, then draw the subtitle on the video by UI, which is supported by the imxplayer.
this solution is using QT by imxplayer, so if you build yocto, should choose QT as target. basicly, aiurdemux send the text to the QT by appsink, then QT draw the text on the UI layer.
when build the yocot, pls using the command as below:
" bitbake fsl-image-qt5"
copy the font libary to the /usr/lib/fonts, then when you play the imxplayer, choose the font you need.
2)another one is blending the subtitle on the video buffer by gstreamer, then output with video
- enable gst pango lib in gstreamer1.0-plugins-base
- change playbin flag to disable native video flag
- basetextoverlay apply patch http://cgit.freedesktop.org/gstreamer/gst-plugins-base/commit/ext/pango/gstbasetextoverlay.c?id=267a8c24af4f02ba6f3075bd589d3c5d1dc826e9
- use following command line
gst-launch-1.0 playbin flags=0x17 uri=file://$VIDEO_FILE suburi=file://$SUBTITLE_FILE