Playing audio:

selecting a subset of say 110 out of 1800 tracks (ie filtered on the subject of say "canal").
The list of the subset has to be stored. On PHP that requires a dedicated area/array. But how much temporary storage do you allocate for multiple users? How many users to cater for? When to decide they have left? It's a jungle out there.

The logical answer is to distribute the job. And that is JavaScript territory.

I well remember seeing the code that a streaming service provided for the radio station when it needed changing. PHP larded with JavaScript (or did I mean the other way round). If the professionals need it, I take my cue from them. (limit of 10 streaming users since you ask)

And at the end of the day - do all your users use HTML5 browsers? When I started this software I tried to get an acquaintance to look at one of my websites and tried a lot of prompting with carefully crafted questions that didn't involve "What version of IE?".

The best analysis came up with IE8. Flash (etc) territory. That was 3 years ago. My software reecognises the possibility. How does PHP do that? I regard the few as valuable. They contribute to my audio, and it is hoped they will keep doing so. It is a collection of old people talking about their life in Stroud. It is Folklore goddamnit.
They are old. They are not computer experts.

Yes, I do know quite a few luddites, and they are not all Folkies! Their mantra is "I HAVE A COMPUTER!". You can assume that is of any vintage. or disenfranchise them!