UHD Bluray - why so "grainy"?

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Batman

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#270148 25-Apr-2020 14:13

I have a selection of 4K blu rays but I have been wondering for a while now why they are so grainy.

warehouse 4K BD -> Xbox one X -> LG 65" C8 OLED [very very min signal processing, settings on Xbox and TV following advice from HDTVtest]

I presume Hollywood adds grain to the movies?

Thanks for explaining to a confused person

(PS I know all of mine are upscaled 2K but it's not the resolution it's the annoying grain)

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#2471083 25-Apr-2020 14:29

The purists want the most film-like experience. Film stock is grainy and this is more noticeable on UHD titles because it has higher resolution and because the films tend to receive less digital noise reduction. At normal viewing distances it's not a problem, but close up it can appear quite distracting. As for added grain, I have no idea. My experience is most modern movies look quite clean.

sdavisnz

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#2471090 25-Apr-2020 14:46

How long is your hdmi cable?

How old is your hdmi cable?

How damaged is your hdmi cable?

Is your xbox set to 4k?

Is your tv set to hdmi enhanced?

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richms

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#2471091 25-Apr-2020 14:47

It really is quite disgustingly distracting I find, and it gets messed up by motion interpolation into a swirling sea of grot, so I have to decide if I watch it with that horridness, or turn off interpolation and get motion sick from the substandard cinematic framerate, or watch it on the small tv so its not a problem.

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#2471154 25-Apr-2020 15:24

sdavisnz: How long is your hdmi cable?

How old is your hdmi cable?

How damaged is your hdmi cable?

Is your xbox set to 4k?

Is your tv set to hdmi enhanced?

Would cable length or quality matter for a digital signal ? It'll either be working or not working.

sdavisnz

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#2471158 25-Apr-2020 15:32

Grainy Image would indicate a fault on a cable or interference.

I'm an AV technician, seen it many times.

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richms

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#2471161 25-Apr-2020 15:38

No, its in the source material. Cable fault results in large lines of dropout or complete static like an old analog TV when off station. No way a cable fault can add grain to a digital image, like there is no way a digital audio cable can colour the sound. Its either getting thru, or damaged to the point that its unusable.

Richard rich.ms

SirHumphreyAppleby

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#2471162 25-Apr-2020 15:42

richms:

No, its in the source material. Cable fault results in large lines of dropout or complete static like an old analog TV when off station. No way a cable fault can add grain to a digital image, like there is no way a digital audio cable can colour the sound. Its either getting thru, or damaged to the point that its unusable.

I wouldn't go so far as to say it's all or nothing. I've seen bad cables result in usable images with green dots all over the place, but there is no way that could be mistaken for grain.

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#2471163 25-Apr-2020 15:50

It's not going to be the cable, it will be intentional processing during mastering.

The director will want to keep the 'feel' of tape and will have asked for a film grain to be put on top of the captured video.

Re: the comment about cables not altering the picture.

Just you wait until 8K (HDMI 2.1 / 48Gbps hits) - then cables will effect the picture!

If the cable can't handle, say, 48Gbps you will still get a picture on your display - but only at the thru-put your signal chain can handle... say, 18Gbps 4K 80-bit 4:2:2.

Put a better cable in (most likely fiber HDMI) and you might get up to 8K 48Gbps @ 60Hz!

Meaning, under the new standard, upgrading your cable can quite literally improve your picture.

In turn this will mean an end to the cry of 'it's digital, so it either works or it doesn't'!*

Where it will really pickle your noodle... is when the end user presses the 'info' button on the TV remote, and the TV reports 8K @ 60Hz! When it's actually displaying an image well under this figure!W

Why's that?

Well, TV's can simply 'cheat' by flashing up the meta-data info from the source, not what it is actually displaying on the panel.

Oh yeah, even then, there'll still be film grain.

HDMI, will the fun and games ever end?

*Unless there's no picture at all

richms

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#2471167 25-Apr-2020 15:54

Damn 4:2:2 - Worst thing ever to allow for in HDMI, even some PCs will default to that on some displays and then you get the complaints about blurry text. And limited range HDMI. Thankfully that seems to not be a thing once beyond 8 bit. But again, Why?

4:2:2 has been an ongoing issue and TVs not showing that in the info screen. No reason to expect that this will get corrected anytime.

Richard rich.ms

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#2471171 25-Apr-2020 15:58

Perhaps the movies you a viewing are shot on film and they are older ones? I notice this too especially on older titles. Its usually how the movie was created.

Shindig

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#2471179 25-Apr-2020 16:18

https://www.reddit.com/r/movies/comments/xcnzc/why_is_film_grain_used_in_films_are_there_any/

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Batman

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#2471426 26-Apr-2020 11:00

thanks guys good to know it's "normal" :(

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#2471427 26-Apr-2020 11:01

Which movie titles? Some movies are intentionally created like this (watched Guy Ritchie's The Gentlemen this week and it's grainy but that's a style). Some old movies can't be moved into digital without the grainy film feel, unless heavily processed.

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#2471458 26-Apr-2020 11:09

to be honest, they are all grainy, some more than others. most grainy one so far is jurassic world! (but that might be coz it's the last one I've watched).

i know it's not the cable because cartoons (HDR and non HDR) are not grainy at all.

all my games on xbox - 4K HDR and non HDR are not grainy at all.

I notice it when i'm sitting 1m away.

notice is but not distracting at 2m away.

not noticable from 3m away.

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#2471572 26-Apr-2020 13:14

Is it grain or noise?

One is physical and the other digital. You will often see on Netflix shows (for example) noise in dark scenes because they use cheaper cameras that have worse performance at the high ISO settings needed to shoot dark scenes.

A movie with a big budget should not have that issue because they can afford top end cameras and operators. If shot on real film, it may have grain or grain may have been simulated for effect.

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