The change in storage space needed for recordings on VM
 

I accidentally recorded All Aboard! The Great Reindeer Migration from BBC4 HD again the other day, and it occurred to me to check how much space they both took, I was curious.

5.41GB - was recorded on 24th December 2018 back when BBC4 HD was on 163
2.3GB - was recorded on 12th December this year.

I'm assuming most of this difference is the switch from MPEG2 to MPEG4. I was expecting the newest recording to be around 3GB, so the difference was much better.

Thought it might briefly interest others who have VM TV how much has changed behind the scenes, and yet how little they may have noticed.

Re: The change in storage space needed for recordings on VM
 

That's a huge difference from 2018 mate.

Re: The change in storage space needed for recordings on VM
 

How did you find out this info? Is it from the boxes themselves?

Re: The change in storage space needed for recordings on VM
 

Yes. You can find it by pressing Info button on a particular recorded episode screen. It shows both a % of box space and the size in GB to two decimal places.

I'm currently watching live stream of my local football team so I can't look it up to be more precise with my words for these instructions.

Re: The change in storage space needed for recordings on VM
 

The HD channels became MPEG4 in January 2018. The difference is down to the new encoders.

Re: The change in storage space needed for recordings on VM
 

Many thanks spiderplant.

I had a feeling new encoders were a part of it, I recall them being mentioned recently but have no idea how long they've been installed. I couldn't remember when the HD channels switched to MPEG4 so wasn't sure what to attribute to the change. How much bigger were the MPEG2 HD channels on VM just before they were superceded?

It's impressive the results, I couldn't really see any difference when I compared scenes.

Re: The change in storage space needed for recordings on VM
 

The new encoders have been gradually introduced since October. The switch to MPEG4 halved the bit-rate, and now it's being halved again.

And if you think that's impressive, see the bit-rates that Netflix are dabbling with:
https://netflixtechblog.com/optimize...g-47b516b10bbb

Re: The change in storage space needed for recordings on VM
 

Some of the initial MPEG-2 HD broadcasts initially were around 16-18 Mb/sec taking up about half of a 38 Mb/sec 64 QAM transport stream (minus overheads).

A quick skim on Digitalbitrate has the current MPEG4 HD channels varying anything between 2 and 7 MB/sec as this depends how many channels are being squeezed in and what prioritisation they are given. Digitalbitrate is currently reporting BBC 4 HD averaging 1.8.

You are probably comparing when the number of HD channels was capped at about 6 per transport stream (a straight average of 7.5 MB/sec once overheads taken out, with BBC4 a lower priority compared to other content on the stream).

Re: The change in storage space needed for recordings on VM
 

Quite possible jfman.

Wow. That's impressive spiderplant. Even Freeview might be able to achieve some previously unthought of things on its HD mulitplexes if those examples are anything to go by.

Re: The change in storage space needed for recordings on VM
 

Only impressive if the picture quality has not suffered.

You have an ideal opportunity to gauge this by watching both recordings.

Re: The change in storage space needed for recordings on VM
 

I did briefly, hence what I said earlier. I couldn't see anything obvious. I'll have another longer look at a later time.

Re: The change in storage space needed for recordings on VM
 

You would think people would notice if there was a deterioration but the evidence from the rapid decline of SD bandwidths and what passes off as SD now vs the introduction of digital would indicate otherwise. Users simply gradually adjusted.

Re: The change in storage space needed for recordings on VM
 

Upscaling tech has got better and helped, but I agree slow changes have got some used to poorer quality, and they don't care enough to moan loudly enough in large numbers.

As I type this I'm currently watching (well, it's on in the background) one of the lower resolution SD Freeview channels in the kitchen 24 inch (circa 2010) TV and it's acceptable. The screen in question has Full HD resolution (via other input sources) but no HD tuner, so I'm not sure how much upscaling it's doing, but it's 10 years old tech (at least).

Re: The change in storage space needed for recordings on VM
 

A good test was always the Olympic swimming and rafting events. Water kills compression algorithms for fun.

Re: The change in storage space needed for recordings on VM
 

Good to know. Thanks. I'll pay particular attention to any water segments then. Though I can't see there being (m)any in the particular show I've got for comparison. :)