Image is too Sharp

[e.motion]

Eventhough I've been reading Doom9's forum for some time now, this is my first post ever so hello to everyone!

I've tried several option setting to encode my movies in Xvid, and I never managed to get good enough quality (even following all the advice that was given on this forum). The latest movie I've tried is Spiderman, wich turns out to be too sharp with some artifacts around objects.

I'm using Gordian Knot to encode Xvid's. The problem is that I've use quite high bitrate ~1200kbits to make a 2CD backup with an AC3 audio track. Is the image too sharp because of the Lanczos resising I've used or is it simply due to the MPEG quantisation?

(Other options: QPel, B-VOP 2:1.5:1, Ultra High search precision, VHQ mode decision, Chroma Motion, Trellised Matrix)

Thank you very much if you could point me in a direction to get out of the dark.

[Sirber]

I think it's on the filtering side, since in theory a codec will not sharpen. You could try to disable QPel also. :D

[Chainmax]

I agree with Sirber. Can you examine a vob and see if the excessive sharpening is already present in the source?

[e.motion]

Thanks for the quick answers... The VOBs are quite sharp indeed.
Would there be a way to smoothen the image a little, for example changing the resizing filter?
Does Qpel sharpen too?

Thanks.

[Teegedeck]

Too sharp? Now that's a rare problem. If there actually are artefacts around objects in the source(!)postprocessing might be a good idea; sounds like a case for deringing:

mpeg2source("your.movie.d2v",cpu2="ooooxx")

If that blurrs the input too much, try:

mpeg2source("your.movie.d2v",cpu2="ooooox")

If it still blurrs too much try a soft bicubic resizer instead.

Another method to soften would be:

unfilter(-2,-2)

And yes, QPel does look sharper.

[Dams]

Get out the Qpel Option and try NeutralResize or add Undot before and after resize.

[Sharktooth]

Use avisynth filters like Undot, Unfilter etc. to improve compressibility.
Get rid of QPEL and "try" without Trellis.
Set Chroma Optimizer in Zone Options (it helps smoothing color transitions), use Adaptive quantization and use a "soft" Custom Matrix or H263.
That should provide the results you want.

[e.motion]

Thank you very much for you answers! Some are quite technical for me since I don't really know how to use AviSynth scripts. I imagine a go at the Avisynth FAQ will be necessary...

By the way, can these AviSynth filters be applied on the Avi directly or should I reencode the movie completely?

Thank you again for sharing your knowledge.

[niamh]

well H263 is in the xvid options, use it instead of mpeg, and neutral bicubic you tick in the avisynth box of gordianknot , instead of lanczos, that ought to make it blurry enough ;)

undot comes enabled by default in gknot if you use the normal avs window, and to use unfilter, say, get the unfilter.dll off the warpenterprises page in avisynth.org, plop it in your avisynth plugin directory, then in gknot, go to edit button in the avs box( right after save and encode), and edit the script manually like this:
loadplugin("c:\program files\gordianknot\avisynthplugins\unfilter.dll")

and , say, below undot, for example, add this line
unfilter(-2,-2)
dont forget to preview for errors, then save the script :)

PS: you need to reencode, unless you want to use some of the avisynth postprocessing filters bundled in ffdshow for playback.. but then it's postprocessing, it won't actually change the state of the encode itself.

[e.motion]

Thank you very much for you detailed explanations niamh! I'll try all this ASAP.

[Sharktooth]

before doing the whole encode test the settings on a small clip of the movie using the same bitrate.

[e.motion]

Originally posted by Sharktooth
before doing the whole encode test the settings on a small clip of the movie using the same bitrate.

Yes, thanks. That's what I am going to do ;-)