- substr: documentation ( source)
- strrpos: documentation ( source)
<?php
$a = "http://hls.v.momocdn.com/live/gdws360abc/playlist.m3u8";
$startloc = strrpos($a,"/live");
$endloc = strrpos($a,"/playlist.m3u8");
echo $startloc;
echo $endloc;
echo substr($a,$startloc+6,$endloc-$startloc-6);