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View Full Version : "dirty" edges even at high bitrates

aand
21st August 2008, 13:42
Hi!
I'm having a problem with a video I'm trying to encode with x264. The source looks sharp and I'm happy with it, the edges are very clear.


After encoding it with CRF 18, the clear contours become blurred, at least that is what I first thought. After trying to compare some screenshots of the two, lossless vs. CRF 18, and failing, I realised it's actually the ringing that makes the lines appear "blurry".
http://img329.imageshack.us/img329/1725/snapshot20080821134401zn6.png
Top is lossless, bottom is CRF 18

What can I do? I mean is there another way than just throwing bitrate at it? CRF 18 is 7Mbps :eek:
I was hoping for something between 1-2 Mbps.
I'm thinking the video is almost black'n'white, so should be easyer to compress.. no?

The comandline is: (I'm using presets from MeGui)
x264.exe --crf 18 --ref 5 --mixed-refs --bframes 16 --b-pyramid --b-rdo --bime --weightb --filter -2,-1 --subme 6 --trellis 1 --partitions p8x8,b8x8,i4x4,i8x8 --8x8dct --me umh --merange 30 --threads auto --thread-input --sar 1:1 --progress --no-psnr --no-ssim --output gnarls.mkv gnarls.avs

Here (http://mihd.net/kxiy7ug) is a 30MB sample of the lossless vid.
DarkZell666
21st August 2008, 14:24
MeGUI's recent x264 builds from the auto update use the Psy-Rdo patch, which isn't friends with sharp edges too much yet AFAIK x_x (or is it psy-trellis specifically ? too lazy to go back and check :p).

Try disabling Psy-Rdo (is it --psy-rd 0,0 ?). If it gets better but it's still not enough, just use CRF 15. Or maybe tweak AQ to be more gentle ?

If you aren't using the recently updated builds, what version are you using ?
Sharktooth
21st August 2008, 15:41
IIRC it's AQ that is messing with edges...
aand
22nd August 2008, 07:57
Disabled AQ and now it looks "clean". :) thanks a lot!
I was using build 940-something. Now using 945 Jarod's patched build.
So..is AQ an 'improvement'? After disableing AQ, bitrate dropped considerably, like 30% now.
I'm happy :D
DarkZell666
22nd August 2008, 12:56
Disabled AQ and now it looks "clean". :) thanks a lot!
I was using build 940-something. Now using 945 Jarod's patched build.
So..is AQ an 'improvement'? After disableing AQ, bitrate dropped considerably, like 30% now.
I'm happy :D

AQ is an improvement in most cases, just not in yours :)
Be Happy, Don't Worry ... lol.
qyqgpower
23rd August 2008, 02:52
In my test, it's AQ2 or noAQ that is messing with low contrast edges.
And the ringing around high contrast edges are mainly introduced by psy-rd and enhanced by AQ2.

bmp samples
http://www.mediafire.com/?80tdgk4iaia

comparing the edge of the shadow
noAQnoPsy OUT
2AQnoPsy OUT
noAQPsy11 OUT

comparing around her collar
1AQPsy11 OUT
2AQPsy11 OUT

best result: 1AQnoPsy