PR new stats

[Niko78]

After talking with @lucasrodcosta he asked me to post a PR here.
I worked a bit to ouput "latency" and "current buffer"
I'm not a dev so I do my best but I'm sure there are better ways to do it

current buffer
hls.on(Hls.Events.LEVEL_LOADED,function(event,data) {
var pos = video.currentTime;
var bufferLen = video.buffered.end(0) - pos;
console.log('CURRENT BUFFER : ' + bufferLen.toFixed(2) + ' seconds');
});

=> I detected an issue about current buffer in my code but I don't know yet how to fix it : when encoder is started if I stop it then restart it, value begins to be negative because of video.buffered.end(0) which is frozen to a very small value (0.0x)

latency (it needs EXT-X-PROGRAM-DATE-TIME header)
hls.on(Hls.Events.LEVEL_LOADED,function(event,data) {
var current = video.currentTime;
var frag = data.details.fragments[0].start;
var tps = current - frag;
var now = new Date();
var unixnow = Date.parse(now)/1000;
var tunix = Date.parse(data.details.fragments[0].rawProgramDateTime)/1000;
var latence = unixnow - tunix - tps;
console.log('LATENCY : ' + latence.toFixed(2) + ' seconds');
});

I made some tests and It works rather well.

Nico

[leandromoreira]

Thanks, @Niko78 we need to have in mind that this only works for the hls.js playback.