Spears & Munsil 4K UHD HDR Benchmark (Test Discs) May 15, 2023

[Penton-Man]

Originally Posted by Balling

ffmpeg

gets around - https://forum.blu-ray.com/showthread...g#post18659241

[Stacey Spears]

Originally Posted by Penton-Man

gets around - https://forum.blu-ray.com/showthread...g#post18659241

When I read that the perseverance rover has a Linux box in it and it's using ffmpeg to compress the video that's beamed back to earth, I thought that was pretty cool!

[5150z]

Originally Posted by Stacey Spears

Do you use PC mode on the 6 series? It seems to stay 10-bit and 4:4:4 chroma vs. the 7-9. It is fixed again on the X. Now they just need to enable Real Cinema (5:5) and we are golden.

Stacey, just to follow up on this. As I eluded to, I force DolbyVision on my Oppo 203, but with forced DV, the 'Video Output Setup in the Oppo menu is completely grayed out. I have had Color Space set to 4-4-4 as I thought whatever it is set at doesn't matter when playing discs with DV. It seems you're saying setting Color Space to 'RGB PC Level' for the 203 is the best/correct solution for these 2016 LG Oleds?

Also, does it matter if Bit Depth on the 203 is set at 10 bit or 12 bit? Or should it always be set to 10 bit? And, if so, why? Thank you again.

[chros]

Originally Posted by Stacey Spears

It seems to stay 10-bit and 4:4:4 chroma vs. the 7-9. It is fixed again on the X. Now they just need to enable Real Cinema (5:5) and we are golden.

Thanks for the info about the 1st part, but the 2nd part is not correct:
using PC mode (same with LLDV!) certain image processings are disabled by LG, resulting in banding / posterization! (Mostly visible with low bitrate streaming content, but it's present with UHD BD content as well)
If you need sample clips for this I can provide them.

[Stacey Spears]

Originally Posted by chros

Thanks for the info about the 1st part, but the 2nd part is not correct:
using PC mode (same with LLDV!) certain image processings are disabled by LG, resulting in banding / posterization! (Mostly visible with low bitrate streaming content, but it's present with UHD BD content as well)
If you need sample clips for this I can provide them.

The banding was fixed on the CX, at least the 48" that I purchased as well as the 88". I have not tested the 55" or 65". I also don't see the banding on Don's C6. The 7, 8 and 9 all have the banding you describe when I tested them.

The banding was caused by dropping to 8-bit and not the controls that were disabled. The controls were disabled because they only function in 4:2:2 and have to be bypassed in PC mode.

On our disc, the smoke in the menus background video has serious banding in PC mode on the 7, 8 and 9. The 6 and X look the same in both PC and normal mode. On our quantization rotate pattern, the bottom 10-bit section looks just like the top 8-bit on the 7, 8 and 9, but not on the 6 or X as PC and normal match.

If you are seeing different, which size?

[Stacey Spears]

Originally Posted by 5150z

Stacey, just to follow up on this. As I eluded to, I force DolbyVision on my Oppo 203, but with forced DV, the 'Video Output Setup in the Oppo menu is completely grayed out. I have had Color Space set to 4-4-4 as I thought whatever it is set at doesn't matter when playing discs with DV. It seems you're saying setting Color Space to 'RGB PC Level' for the 203 is the best/correct solution for these 2016 LG Oleds?

Also, does it matter if Bit Depth on the 203 is set at 10 bit or 12 bit? Or should it always be set to 10 bit? And, if so, why? Thank you again.

DV always outputs 12-bit 4:2:2. In player-led it is sent out and signaled as YCbCr 12-bit 4:2:2 (aka HDR12). In TV-led, it is sent out as 12-bit 4:2:2 and signaled as 8-bit RGB to trick AVRs into not breaking the signal. Be sure to set your player to TV-led and not auto or player-led.

And no, don't set your player to RGB full range. There is a special mode on the LG known as 4:4:4 mode. You enable this by changing the input label icon to the one called PC.

As mentioned, this only works on the 6 and X series, at least in my testing. The 7, 8 and 9 series have serious banding when you use PC mode.

To test and see the difference you can look at two patterns.
1. Chroma Zone Plate 10,000 version. I would look at the chroma and the Cb legal.
In normal mode, the left and right 3rds will be visibly dimmer than the center third. This is because the center, which has thicker lines, is lower frequency / resolution than the sides, which is higher frequency / resolution. The dimming is a roll-off of high frequency / resolution detail.

In PC mode, the brightness is uniform across the entire image, which means no roll-off.

Here is the kicker! Even though you are starting with a 4:2:0 source and sending in 4:2:2, you still get the dimmer sides in normal mode and proper in PC mode. This suggests that there are multiple conversion between 4:2:2 and 4:4:4 that take place in the displays pipeline. Otherwise, normal mode would be just fine.

2. Quantization rotate. The 10-bit bottom should be smoother than the 8-bit simulated top. If you enable PC mode on a 7, 8 or 9, the top and bottom have the same exact banding. On my X, the bottom still looks good while on my 9, the bottom matches the top, lots of banding.

The smoke in the background of the menu is also a good test. There is some minor banding in the smoke in normal mode on the LG and massive banding in the smoke in PC mode. On the JVC projector, it is as smooth as can be since the banding is not in the source itself but caused by the display.

Hope this makes sense, if not, please let me know.

It takes a bit of time to switch between normal and PC mode, which is annoying.

On the CX, Real Cinema is also disabled in PC mode. This one is odd as it should not work in 4:2:2 and I have asked LGE in Korea to please re-enable it. We shall see if it gets re-enabled in a future model.

[Sledgehamma]

Stacey can you explain what causes the light blue or yellow “shadow” around the Diamonds?

[Stacey Spears]

Originally Posted by Sledgehamma

Stacey can you explain what causes the light blue or yellow “shadow” around the Diamonds?

Looks like chroma ringing to me. Neither my bilinear or bicubic up sampling algorithms produce those results. To be sure it is that and not something HDR related, can you try the SDR version?

[Sledgehamma]

SDR doesn’t exhibit the same issue:



Looks similar, although less pronounced on my Philips 804 and Apple TV 4K for the HDR pattern. Zidoo via VS10 looks best.

[chros]

Originally Posted by Stacey Spears

The banding was fixed on the CX, at least the 48" that I purchased as well as the 88". I have not tested the 55" or 65". I also don't see the banding on Don's C6. The 7, 8 and 9 all have the banding you describe when I tested them.

The banding was caused by dropping to 8-bit and not the controls that were disabled. ...

On our disc, the smoke in the menus background video has serious banding in PC mode on the 7, 8 and 9. The 6 and X look the same in both PC and normal mode. On our quantization rotate pattern, the bottom 10-bit section looks just like the top 8-bit on the 7, 8 and 9, but not on the 6 or X as PC and normal match.

First of all, thanks for your kind reply, it's good to know that these are fixed in CX, but there is another issue, namely posterisation in low APL scenes (see below), and according to other CX owners this issue is still there.

Originally Posted by Stacey Spears

The controls were disabled because they only function in 4:2:2 and have to be bypassed in PC mode.

I see, thanks, but I wasn't talking about these controls but other image processing algos, see below.

Originally Posted by Stacey Spears

If you are seeing different, which size?

I have a 2018 model (65B8, but C8 is identical, and size doesn't matter) and these sets produce brutal posterisation in low APL scenes with HDR content (HDR10, and LLDV as well, see below). It's like some basic processing is missing in low APL (darkish) scenes with LG's tonemapping (with and without LG's DTM) that destroys the image (madvr tonemapping can't help this). Interestingly I haven't spot this weird thing in normal/high APL scenes.

Download this untouched UHD BD sample (~3.6GB). Set output to Full range RGB 12 bit (I use PC with nvidia card + madvr.)
There are at least 3 different problems here (maybe 2nd and 3rd is the same):
- banding: e.g. red light of torches around @03:20
- added noise: @00:32, around @01:16
- posterisation: clouds in dark scenes, @03:20, @03:25, etc.

Posterisation is just crazy sometimes! That's the biggest problem and this has nothing to do with 8bit vs 10bit as it's also present with 8bit.
8bit YCbCr 4:4:4 (limited) eliminates a lot of them, but there's still banding and the nasty posterisation still exists e.g. @03:25 (although removes it from @03:20).
None of this happens in non-PC mode even with RGB Full 12bit!

Watch it in dark room (without lights), pause the playback at problematic parts and switch back and forth between PC and non-PC mode to clearly see the difference.

Now, if you managed to see the issue, then next test is DoVi with Oppo :
- remux this file from "mkv" into "ts" container with tsmuxer nightly (so Oppo can convert it into DV on the fly)
- set HDR option in Oppo to: "Dolby Vision"
- take a look at the problematic parts with tv-led and player-led

I see the very same posterisation using player-led DoVi (LLDV) just like in PC mode with HDR10 content!!! (no matter for DoVi whether PC mode is selected or not).
it's like LG TV is switched to Low Latency DV mode (just like Sony Oleds), so it disables certain image processings, just like in PC mode with SDR/HDR10 content!!!

(I have written about this issue here, and forcing DoVi in Oppo here, along with a workaround for a bug with HDR10+ content).

[5150z]

Originally Posted by Stacey

[B

You enable this by changing the input label icon to the one called PC.
[/B]
As mentioned, this only works on the 6 and X series, at least in my testing. The 7, 8 and 9 series have serious banding when you use PC

Stacey, how does one do the bolded above on the 6 Series LG Oleds? I've gone thru all the menu options on my B6 and failed to see it. Unless I'm missing it. Is it in the Service Menu?

[Stacey Spears]

Originally Posted by 5150z

Stacey, how does one do the bolded above on the 6 Series LG Oleds? I've gone thru all the menu options on my B6 and failed to see it. Unless I'm missing it. Is it in the Service Menu?

They change it every year, so I don't recall on the 6 series. On the 9, you hold down the input button extra long and it takes you to the menu to change input labels.

[wxman2003]

Originally Posted by 5150z

Stacey, how does one do the bolded above on the 6 Series LG Oleds? I've gone thru all the menu options on my B6 and failed to see it. Unless I'm missing it. Is it in the Service Menu?

To change that HDMI port to PC mode on your B6, press and hold input button on the remote. Select the HDMI port you labelled for your 203. Then select edit icon. Scroll down to PC and select that. However, when doing that. it locks color gamut to wide, and greyed out. So if you want to watch SDR, you will need to change the icon back.

[David M]

Originally Posted by wxman2003

To change that HDMI port to PC mode on your B6, press and hold input button on the remote. Select the HDMI port you labelled for your 203. Then select edit icon. Scroll down to PC and select that. However, when doing that. it locks color gamut to wide, and greyed out. So if you want to watch SDR, you will need to change the icon back.

I use the PC mode on the LG C7 I use at home for video games. It passes full 4:4:4 chroma through and has low input lag, but as Stacey says, it's only useful for 8-bit sources and will cause crazy banding on anything higher on that display. Glad to hear they addressed the latter point.

To avoid the annoyance of having to keep re-labeling the input, I just got an AV receiver with 2 HDMI outputs and connected 2 cables, so I can leave one input dedicated to the PC Mode.

[5150z]

Originally Posted by wxman2003

To change that HDMI port to PC mode on your B6, press and hold input button on the remote. Select the HDMI port you labelled for your 203. Then select edit icon. Scroll down to PC and select that. However, when doing that. it locks color gamut to wide, and greyed out. So if you want to watch SDR, you will need to change the icon back.

Many thanks for this sir. The good thing is I don't watch SDR content, only HDR. SDR on my 105D.

[Stacey Spears]

Originally Posted by Sledgehamma

SDR doesn’t exhibit the same issue:



Looks similar, although less pronounced on my Philips 804 and Apple TV 4K for the HDR pattern. Zidoo via VS10 looks best.

I believe it is chroma ringing and it stands out more in HDR because it is HDR. Here are some full images that I convert to RGB (8-bit) using bicubic and bilinear upsampling. This is an HDR image, but you will most likely be viewing it in gamma, so it is not as obvious. If you zoom in very far using nearest neighbor, to avoid any interpolation or smoothing, you will see it.

You will see the same chroma ringing in bicubic but not in bilinear.

Bicubic


Bilinear


Bilinear - 709 instead of 2020 upsampling / color conversion


It is probably best to save it to your local machine and zoom in.

This is the new version where I mentioned the added color bars in the color space conversion section.

[wxman2003]

Originally Posted by 5150z

Many thanks for this sir. The good thing is I don't watch SDR content, only HDR. SDR on my 105D.

I would like to hear what you think of image quality with DV when you switch that port to PC. I don't notice any difference when I labeled the port PC. I noticed when set to PC, Black level in the picture setting switches from Auto to Low and is greyed out.

[Stacey Spears]

Originally Posted by wxman2003

I would like to hear what you think of image quality with DV when you switch that port to PC. I don't notice any difference when I labeled the port PC. I noticed when set to PC, Black level in the picture setting switches from Auto to Low and is greyed out.

What is interesting is that when I put the C9 into PC mode, Dolby does not have the banding, just HDR10. This shows Dolby going through a different path in the display. I need to double check and confirm, once we are further along.

[chros]

Originally Posted by Stacey Spears

What is interesting is that when I put the C9 into PC mode, Dolby does not have the banding, just HDR10. This shows Dolby going through a different path in the display. I need to double check and confirm, once we are further along.

That's correct, PC mode doesn't apply to DoVi. But if you force Oppo to player-led: bum, we get the very same issues just as we get with PC mode! (no matter whether PC or non-PC mode is selected)
(My other reply is still pending - not visible - for whatever reason)

[wxman2003]

Originally Posted by chros

That's correct, PC mode doesn't apply to DoVi. But if you force Oppo to player-led: bum, we get the very same issues just as we get with PC mode! (no matter whether PC or non-PC mode is selected)
(My other reply is still pending - not visible - for whatever reason)

Since I have an E6, it can only handle TV-led DV. I guess I will just leave everything as is, since I don't notice any difference.