Mpeg decoding

I have just assembled TVHeadend with a couple of tuners on a Pi4 and using Libreelec running on a Pi 3B to view the result which seems to all work as intended (OK, I won't pretend I managed it first go!)

I made another player using a pi 4 with similar results and then tried it with a pi zero which plays HD terrestrial and my own videos well (but perhaps using a lot of the available processing) but no pictures on SDTV.

I'm imagining this is because I need an MPEG licence for the zero and the others are coping with just software decoding, but I'll admit to being a bit surprised it doesn't even try.

I don't mind paying the modest sum for the licence and even rolling my sleeves up to install it via SSH ( as seems neccessary) but I'd like to know if this really is the issue or if I'm just missing something...

I hope I haven't missed looking in the right places but I was surprised not to find any discussion on this hence the question...

To answer my own query (if it helps someone else) the MPEG2 licence did indeed resolve things and SDTV works.

Overall the Pi Zero just about runs LibreElec adequately. It's noticably slower than a 3 or 4, HD occasionally a shows a slight hesitation on some sources and the CPU usage looks quite high, but for me it means I can run LibreElec on a Pi zero attached to a projector which does not quite have room to attach a full-sized Pi and so would need trailing wires. This makes for a neater and more portable sytem for domestic bliss but otherwise I'd duck the problem and use a Pi 3 or 4!

Oh, Incidentally, I used a usb adaptor for a wireless remote which was cheap and worked without any fuss but, because the two micro USB sockets are quite close, it did require a bit of 'mechanical easing' to make the usb adaptor fit next to the USB power connector