Im working with HLS HD streams via live channels . Everythings works fine , outstanding my requirements , but i need to include a subtitle stream with the video and audio. it is possible to use LIVE subtitles in HLS ? these subtitles streams come along the audio and video , generally in DVB subtitle format.
but many channels have no sense without subtitles. maybe putting a first instance of ffmpeg in order to burn subtitles into original video stream , but this require more complex process and probably another machine to do this first.
We currently have support for subtitles on live and on-demand SmoothStreaming and on-demand HLS. This is all in SMPTE-TT format. We're looking at supporting 608-format closed captions for live HLS, but I don't have any info on potential timing for you at this time
In order to get closed captioning working, all you have to do is set the subtitleUrl content meta data parameter to the TTML url and turn on and off the captions using the new roVideoScreen method ShowSubtitle( Boolean enable).
ok. i solve this issue this a lot of processors. first decode to mpeg2 , then merge the dvb subs , then recode to h264 , works well , even with variable fps (crf=20) , with a final resolution of 850x480 (from 1280x720) in realtime , via an i7 6cores 3.4Ghz. next week i post the data. i test some decoders , works best with ffmpeg , but vlc is more stable chopping HLS. ffmpeg 10.5 only (at least in centos 6.3 64bits), other versions do not work properly selecting streams from dvb multicast udp.
maybe i need to make another post : clues to select reverse-forward ? on a simple m3u8 list with 8 segments , ever start at the oldest, giving no chance to point to the newest , or at least the subsequent. theres may be an interesting point . the proccess of encoding takes 99% of processing , while chopping takes only 0.3% so , with two (or more , via unix tee) you can have (and offer) many m3u8 lists from same "live" HLS with only 9sec of delay (3segments od 3 sec), or "recorded" HLS from past hour and so on. i tested up to 1440 segments of 1 min , with m3u8 lists of last 60 - 120 - 180 -etc segments .
but i cant jump from segment to another , in order to forward-rewind the "live" HLS. it is possible?