support lhls option

First, thanks for providing this. It has been very useful to help me bootstrap my prototype.

I quickly implemented something, and got it working this morning, but the latency is 10-15 seconds. I tried the tuning you suggested (t=.5, l=24, s=100), but it is still lagging at about this rate.

I came across the -lhls option, which seems to be available as an experimental feature in ffmpeg 4.1, and I am wondering if you have looked at this option.

I am a little confused by the option as I tried to explain here:

https://stackoverflow.com/questions/65459568/confused-about-lhls-in-ffmpeg

I have looked at your server.js code, and I would like to take a stab at implementing this, but only after I clear up the confusion about it. There is also a comment about the 'dash' output not working with a file in this thread:

https://stackoverflow.com/questions/56700705/how-to-enable-lhls-in-ffmpeg-4-1

Which may mean this won't work in any case, or at least not yet.

I was just wondering if you had looked at this experimental option and if it is something you think is worth exploring.

I am available to contribute as well.

Thanks.

Start by reading server.js and reviewing the ffmpeg 4.1 -lhls option and the linked discussions. Determine whether the existing DASH output can support LHLS and whether the option is viable for this project; completion would require a clear implementation scope before coding begins.