mpeg2 -> x264 image issues (artifacts in dark areas)

[honelnik]

Hello all,

I've got quite an issue with my vob to x264 encode, what I'm doing is simple

x264.exe --crf 19 sample.mpg -o sample.mkv

and I'm experiencing a "ghosting" or some sort of artifacts in the dark areas of my encode.

I've googled for quite some time on this but couldn't find anything relevant to my case.
Could anyone please help me on this?

I've attached sample.mpg and sample.mkv after conversion.

https://docs.google.com/uc?id=0BzaksiVeixjiXzJ5NXROQjdhVGM&export=download&hl=sk
https://docs.google.com/uc?id=0BzaksiVeixjicGYyNHRvUk9FRk0&export=download&hl=sk

Thank you in advance

[poisondeathray]

Original MPEG2 is encoded interlaced NTSC (59.94i) , and contains interlaced content - but you didn't specify interlaced encoding in x264 commandline , nor did you mention applying any deinterlacing filter.

[honelnik]

Hello,

thanks for the reply, the thing is I used this avs:

LoadPlugin("DGDecode.dll")
DGDecode_mpeg2source("E:\!\!enc\encode\Seventh Heaven\VTS_01_1.d2v", info=3)
LoadPlugin("ColorMatrix.dll")
ColorMatrix(hints=true, threads=0)

LoadPlugin("SmoothDeinterlacer.dll")
SmoothDeinterlace(doublerate=true)
crop( 0, 60, 0, -60)
BicubicResize(720,400,0.333,0.333)


I thought some of it might cause the artifacts so I kept on removing stuff, until I was left with just the source line, with the same artifacts.


Thanks

[poisondeathray]

I'm experiencing a "ghosting" or some sort of artifacts in the dark areas of my encode.

Which artifacts are you referring to specfically? Describe more clearly

Are you referring to interlace/aliasing issues or noise in the flat dark areas ?



Note smoothdeinterlace is very old filter and causes artifacts (aliasing edge artifacts)

Better modern deinterlacers apply temporal/spatial interpolation algorithms to fill in the missing lines

Normally you either encode it interlaced (like the original), and let your playback device do the deinterlacing on the playback , or you use a better deinterlacer.

[honelnik]

When playing the file in MPC HC there's a sort of an "overlay" when the angle of the camera changes (there's some "remnants" of the previous scene which disappears after a second or two, this happens around 7th second )

what kind of deinterlacer would you recommend if I may ask?

When playing my avs directly I can't see the noise in the dark areas and everything looks ok.



I reckon you've noticed I'm quite a noob so any advice is appreciated.

[poisondeathray]

When playing the file in MPC HC there's a sort of an "overlay" when the angle of the camera changes (there's some "remnants" of the previous scene which disappears after a second or two, this happens around 7th second )

This crossfade is in the original source . Unless you were referring to something else?

what kind of deinterlacer would you recommend if I may ask?

QTGMC would be a better deinterlacer, but very slow at default settings. You can use faster presets and still get very qood quality

[poisondeathray]

so any advice is appreciated.

Also you don't need colormatrix for a sd=>sd encode .

When using a deinterlacer you should specify the field order by examining the separated fields. If you don't know how look at this miniguide
http://neuron2.net/faq.html#analysis

Here is an image quality example comparing smoothdeinterlace vs. QTGMC - you can see the jaggie aliasing artifacts produced by smoothdeinterlace

AssumeTFF
SmoothDeinterlace(doublerate=true)

AssumeTFF
QTGMC(preset="faster", sharpness=0.75)

[honelnik]

wow that's definitely better....thanks a lot!

however my main issue still remains, let me post another clip where you can see it properly

this is what I see when playing avs:



this is what I see when playing encode in MPC HC (however windows media player does a better job on covering it up)



it's all over the image, but best noticed about the area with the light. And it just disappears at 5th sec

same source, encode below
https://docs.google.com/uc?id=0BzaksiVeixjiaG1Lc0kzaVViNjA&export=download&hl=sk

[poisondeathray]

It's not apparent in your encode.

This is from your encode , same frame 189, sample1.mkv




Perhaps it's a playback configuration issue,? What renderer and decoder are you using? Do you have graphics card and monitor calibrated ?

For example if you are using VMR9 or 7 renderless, the levels will be elevated and you will see noise that you shouldn't normally see

[jagabo]

Turn off the graphics card's noise reduction. And the sharpness, edge enhancements, and all other enhancements too. All they do is screw up the image.

Yadif() is good alternative if you find QTGMC() to be too slow.

Mpeg2Source("sample.d2v") 
AssumeTFF()
Yadif(order=1, mode=1)

Mpeg2Source("sample.d2v") 
AssumeTFF()
QTGMC()

x264.exe --preset=slow --aq-mode=2 --aq-strength=2.0 --crf=18 --sar=8:9 --output %1.mkv %1

[hello_hello]

this is what I see when playing encode in MPC HC (however windows media player does a better job on covering it up

Can you describe, "does a better job of covering it up"? Are the black levels (contrast/brightness) the same? If not, one player is playing back using the wrong levels.

Edit 1: Yes jagabo's screenshot of the same video seems to indicate MPC-HC is using the wrong levels which is why the banding/blocking in his screenshot is far less obvious.
Edit 2: Nah, I'm wrong about the levels I think. I just tried changing them using your sample and it still didn't look that bad but was much lighter than your screenshot so I don't think that's it. Maybe jagabo is correct about other video card settings though.

I think you've also got one of those hard to compress videos. CRF19 may not be good enough. You may have to use at least CRF 16, although I'd try encoding using a slower x264 speed preset first ("--preset slower", or "--preset veryslow" etc) then if the result still isn't good enough try CRF 18, then CRF 17 etc.

[poisondeathray]

I replicated what something close to what you are seeing in MPCHC by choosing "skip deblocking always" in ffdshow (configuring ffdshow to be the h264/avc decoder) . (The other difference might be you took screenshot in jpg, I took it in png (lossless) ) . I believe it's a playback configuration issue, either decoder or renderer

[honelnik]

hello all,

was kinda busy for few days so didn't have a chance to fiddle around with this...

first of all...you've helped me a lot, QTGMC is a big boost over smoothdeinterlace and the settings from jagabo i got pretty darn pleasing results...

I'm not experiencing the "artifacts" in my encode anymore, thanks to all of you