HDM in UHD

Roy

The BBC iPlayer on our aging 2015 Samsung TV won’t do the 4K the set is capable of, but the iPlayer on our DTR-T4000 will.

Have better than 24Mbps internet, set the YouView box for 4K output, set the iPlayer for Best Quality, and when you pull up HDM, there should be a little ‘UHD’ flag beside it.

Well worth rewatching now we have this, we reckon.

John L

Hi Roy,
One of my Samsung Smart tv's is 2014 & doesn't do 1080p on Youtube. Only upto 720p.
Maybe it's me, but I thought the tv used to stream at 1080p, Maybe Youtube/Samsung have reduced resolution or I've not noticed until I checked recently? I know our new 4K Samsung TV purchased last year, goes upto 4K (with buffering if you turn the resolution up past  1080/1440p - I just either turn it to auto or switch to either 1080 or if I can 1440p.  I assume the TV max. resolution overrides the Youview box in most cases? Does the DTR-T4000 resolution adjust to full 4K? John L

Anaglypta

John L said:

Hi Roy,
One of my Samsung Smart tv's is 2014 & doesn't do 1080p on Youtube. Only upto 720p.
Maybe it's me, but I thought the tv used to stream at 1080p, Maybe Youtube/Samsung have reduced resolution or I've not noticed until I checked recently? I know our new 4K Samsung TV purchased last year, goes upto 4K (with buffering if you turn the resolution up past  1080/1440p - I just either turn it to auto or switch to either 1080 or if I can 1440p.  I assume the TV max. resolution overrides the Youview box in most cases? Does the DTR-T4000 resolution adjust to full 4K? John L

Hi @John L

Certainly during lockdown YouTube throttled back the resolution to allow more people to access at a lower bitrate. Not sure whether they have restored YouTube to normal operations yet.

John.

John L

Hi John,
That would explain it! Thank you.
Going off topic slightly, I know that YouTube has currently crashed on Freesat App.
Hopefully they will improve service very soon. John L

Roy

John L said:

Hi Roy,
One of my Samsung Smart tv's is 2014 & doesn't do 1080p on Youtube. Only upto 720p.
Maybe it's me, but I thought the tv used to stream at 1080p, Maybe Youtube/Samsung have reduced resolution or I've not noticed until I checked recently? I know our new 4K Samsung TV purchased last year, goes upto 4K (with buffering if you turn the resolution up past  1080/1440p - I just either turn it to auto or switch to either 1080 or if I can 1440p.  I assume the TV max. resolution overrides the Youview box in most cases? Does the DTR-T4000 resolution adjust to full 4K? John L

Hi John L

I can try this, but where do I see what YouTube is sending?

With your new TV, what speeds are you getting from your ISP to it, WiFi or Ethernet, depending on how it is connected?

A 4K TV is always going to show a 4K picture, so if you feed it a lower spec signal, such as HD, it does a thing called upscaling, where it synthesises extra pixels to fill in. With HD, it has to invent three pixels in every four; with SD, fifteen in every sixteen; so the algorithm it uses is very important.

The DTR-T4000 can likewise do this upscaling, so if you give it an HD signal and ask it to output 4K, it will invent three more pixels for every one it is given, and pass then to a 4K TV which will faithfully display each one.

Or you can set the T4000 to output HD, so it won’t invent any pixels for an HD signal, and will pass the signal unchanged to the 4K TV, which then itself has to invent three pixels out of every four.

I judge our Samsung TV as better at upscaling (inventing those three pixels out of every four) than the T4000 is.

But given a UHD/4K signal to work with, you need the YouView T4000 box set to output the 4K it gets unchanged, and the TV to show it unchanged.

Which is how we were watching HDM this afternoon.

I did a bit more digging, and bust the T4000 back to 1080p, expecting the iPlayer to detect this, and stop offering UHD on HDM. It didn’t. 😢

So the T4000 still got 4K, had to bust it down to HD by throwing away three pixels out of four, and passed it to the TV, which then had to invent three new pixels out of four.

They were not the same ones 🙀

If I can, I will try to get some screenshots of the awfulness of this; and I will be asking the BBC if they think they ought not to be supplying UHD to a device that isn’t outputting UHD at the moment, even if potentially it could.

John L

Hi Roy,
Might not be the fastest, but we are getting 17.58mbps download and 0.91mbps upload.
Understand most of what you explained ref upscaling. It is a bit of a minefield at the moment. I was having a look at the 4k YouTube videos last week and was stunned at true quality when you actually get true full 4K picture. I might contact my ISP John Lewis (Plusnet) and see if they can increase speed slightly, so I can try and get more stable streaming at the higher resolution. I think sometimes we are getting a lower broadband speed at times. John L

Anaglypta

@Roy
To see what YouTube is sending go into settings>general and enable "stats for nerds". When you play a video you'll get - well, stats for nerds
John

Roy

John L said:

Hi Roy,
Might not be the fastest, but we are getting 17.58mbps download and 0.91mbps upload.
Understand most of what you explained ref upscaling. It is a bit of a minefield at the moment. I was having a look at the 4k YouTube videos last week and was stunned at true quality when you actually get true full 4K picture. I might contact my ISP John Lewis (Plusnet) and see if they can increase speed slightly, so I can try and get more stable streaming at the higher resolution. I think sometimes we are getting a lower broadband speed at times. John L

I have fast.com in my browser. A single tap tells me the speed in my location (it falls off room by room as I move away from the router, and can vary even within that room).

John L

Thanks Roy. I will check this out when I get a moment & see what results I get.
John L

Roy

Apropos of HD and UHD, here’s the same screenshot, as close as I could get it, in three resolutions:-

HD - BBC iPlayer on my Samsung JS9000, their 2015 flagship, upscaled to 4K:, 3 pixels in every 4 interpolated-

UHD - the BBC iPlayer on my T4000 in 4K 10 bit, through that same Samsung TV, pixel for pixel :-



And the result of setting the T4000 to 1080p, but the iPlayer still supplying the UHD version of the programme, so the T4000 busts it down to 1080p by dropping 3 pixels out of 4, and then the TV upscales it back to 4K, by synthesising 3 new pixels for each 1 supplied:-

That latter makes a surprisingly good fist of this, but expand the image and look closely at Billy’s cheek, and the square artefacts resulting from the process; from which we may assume that the downscaling the T4000 does does not produce anything quite like the BBC’s HD frame.

scott

@Roy - looks even better in 4K HLG

John L

John L said:

Thanks Roy. I will check this out when I get a moment & see what results I get.
John L

jimb

For UHD fans "Vigil" the new BBC drama is available in UHD on iPlayer.