[FFmpeg-user] Pipe subtitles to ffmpeg exe

[Sylvain]

HI, 

I am using ffmpeg to encode and mux a SPTS mpeg-ts with H264 video. I provide the input pictures thru a pipe ,and it works fine. But i need to add some DVB subtitles to the SPTS stream, and i am searching a way to provide the subtiles thru another pipe/named FIFO.

Despite mutiple trials, i am not able to generate the subtitles in this way. Note that the subtitles are generated by my own application, so i can format them in any needed format.

The command i use for the video : 
    ffmpeg -re -r 25 -f rawvideo -vcodec rawvideo -pix_fmt yuv420p -s 720x576 -i - -an -vcodec libx264 -tune zerolatency -preset veryfast -x264opts intra-refresh:keyint=12:fps=25:bitrate=1800 -f mpegts -muxrate 1800K udp://localhost:54320?pkt_size=1316

Ideally, i would like to add another input for subtitles like this : 
mkfido subtitles.fifo
ffmpeg...  -i subtitles.fifo -scodec dvbsub ....

So what could be the format of the data pushed into subtitles.fifo ?

Thanks for your help, 

Regards, SF