Welcome to Doom9's Forum, THE in-place to be for everyone interested in DVD conversion.

Before you start posting please read the forum rules. By posting to this forum you agree to abide by the rules.

 

Go Back   Doom9's Forum > Video Encoding > MPEG-4 AVC / H.264

Reply
 
Thread Tools Search this Thread Display Modes
Old 9th January 2018, 00:55   #1  |  Link
TomArrow
Registered User
 
Join Date: Dec 2017
Posts: 27
Issue with x264 grain retention around edges (possibly bug?)

I hope this is the right forum, first timer here.

Trying to encode something with the following settings:
Code:
x264.2851kMod.10bit.x86.exe --preset=veryslow --tune=grain --b-adapt=2 --deblock=-4:-4 --rc-lookahead=60 --keyint=400 --min-keyint=40 --me=umh --merange=64 --psy-rd=1.5:0.15 --aq-mode=1 --qpstep=40 --partitions=all --no-dct-decimate --bframes=16 --no-dct-decimate --no-fast-pskip --deadzone-inter 0 --deadzone-intra 0 --aq-strength=1.0 --trellis=2 --qcomp=1 --subme=11 --ref=8 --crf 24.0 --output="Escape-Trailer-test.264" --profile high444  --input-csp i444 --output-csp i444 --input-res 1920x796 --input-depth=16 --frames 3601 --fps=24000/1001 -
There's no input file because I'm piping from ffmpeg.

Anyway, this is an issue I had with multiple encodes in the past, it's nothing 4:4:4 exclusive.

The issue is that while grain is usually retained very nicely, this simply doesn't seem to work when there are edges in the image. Worst example is a sharp text overlay. Around this text, everything is a blurry mess and whatever little grain structure is preserved there, is static and doesn't "move" like grain should.

Lower CRF values do help it, but dramatically increase bitrate, which I feel is unjustified considering that the rest of the image looks fine.

Now mind you, it's not so horrible as to be noticeable from a normal viewing distance on my LCD, but I'm an old pixel peeper and it annoys me, because it's just ugly. Like a part of the image around the text is static while it should be full of grain.

Any clues?
TomArrow is offline   Reply With Quote
Old 9th January 2018, 16:55   #2  |  Link
poisondeathray
Registered User
 
Join Date: Sep 2007
Posts: 3,825
The "halo" effect of "grainlessness" around objects is partially byproduct of AQ which tends to redistribute bits from edges. Notice the default tune grain preset has it set to 0.5, but you increased it to 1. Try lowering the AQ strength
poisondeathray is offline   Reply With Quote
Old 9th January 2018, 17:18   #3  |  Link
TomArrow
Registered User
 
Join Date: Dec 2017
Posts: 27
Hey, thanks. Yes, I thought that might be the reason. But lowering the aq makes the shadows look terrible/static-grainy, which is much worse than this problem.

Isn't there some additional switch to counter specifically this problem?
TomArrow is offline   Reply With Quote
Old 9th January 2018, 17:26   #4  |  Link
poisondeathray
Registered User
 
Join Date: Sep 2007
Posts: 3,825
Quote:
Originally Posted by TomArrow View Post
Hey, thanks. Yes, I thought that might be the reason. But lowering the aq makes the shadows look terrible/static-grainy, which is much worse than this problem.

Isn't there some additional switch to counter specifically this problem?
That is the switch is most responsible for the redistribution. It's not just object edges, it takes away from frame edges too

Preserving grain needs bits. There is no way around it. Use higher bitrate / lower CRF if you want to use a higher AQ strength

Or change your strategy and prefilter degrain/denoise to reduce the amount of grain
poisondeathray is offline   Reply With Quote
Reply

Tags
encoding, grain, problem, x264

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +1. The time now is 15:18.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2019, vBulletin Solutions Inc.