Problem with resize: Jagged Lines

[wilder]

hello..
i have use lanczosresize before with no problem, but this time..
it produce jagged lines..
i resize it from 480p to 368p..

why is this happening? never before it happen..
i don't use any other filter except FFVideoSource and LanczosResize..

here is the snapshot
original : http://i575.photobucket.com/albums/ss19 ... iginal.jpg
jagged: http://i575.photobucket.com/albums/ss19 ... jagged.jpg

if someone know, please tell me OK?
thank you

[Scintilla]

1) I'm not seeing the problem.
2) Both of those shots are 1024x578, not 480p or 368p.

Maybe you have the wrong URLs?

[wilder]

i took the snapshots in full screen while playing in MPC..
the different is not that obvious but in other parts of the video, it looks ugly..

this is another example..
look at her mouth..
original: http://i575.photobucket.com/albums/ss19 ... inal-2.jpg
jagged: http://i575.photobucket.com/albums/ss19 ... gged-2.jpg

also, i noticed that there are black border at left and right of the jagged picture..
i don't remember adding a border..
is this common when using FFVideoSource?

thanks

[Qyot27]

It looks like edge noise and/or slight banding.

What decoder are you using in MPC? CoreAVC, or ffdshow? If CoreAVC, then it's applying additional post-processing before showing it. The same *could* also be true with ffdshow, but it's less likely by default. FFVideoSource will not show the video with additional post-processing (well, it has the ability to perform pp, but those are function calls that advanced users would be inclined toward). What you're seeing is the video how it really is.

Hit it with a temporal/spatial smoother and a debanding filter and it should be improved. In my case that would be something like deen("w3d",3,6,8,8,8).gradfun2db(2.0) - but there's other smoothers out there to do the work if you don't want to use deen.

[wilder]

In MPC i use ffdshow..

to see the difference better, here videos i uploaded:
original:

http://www.mediafire.com/?24fzzlfexmw

jagged:

http://www.mediafire.com/?jir0mujz4e3

actually, i convert 720p to 480p first. then 480p to 368p. i think this way the file can compress better..
and i'm using x264 with deblock settings -2,-1. does this has something to do with the problem?

sorry if I break forum rules.
thank you

[Zarxrax]

First off don't test the quality of your videos in MPC. There are too many variables to account for. Look at it in AvsP or virtualdub.
Next, don't resize twice, its unnecessary.
Finally, decreasing the deblock settings in x264 will make blocks and other artifacts more noticable, which *may* be contributing to the problem. I would highly recommend leaving them at 0 or even setting them to positive values.

[wilder]

thanks..
i will use no-deblock, it's safer this way..

[wilder]

I think the problem is not with the deblock..
I add FFT3DGPU with sigma=20 and the jagged lines still there..
maybe a problem with renderer? i open it in virtualdub too but also jagged..
the jagged lines only appear/clearer in 368p while in 480p it's not that clear..
someone know about this?
thanks

[Qyot27]

Now that I took a look at the samples in motion, I'm convinced that what you're seeing is - considering you said you were using lanczos as your resizer - ringing artifacts. It's the Lanczos algorithm that creates it. The possible solutions are to pick a different resizer (you could try the Spline family of resizers, for instance), or to look for a specific anti-ringing plugin. I don't know of any offhand, though.

As a general tip when asking for help with a source, don't use JPEG for screenshots. Use PNG, because then there won't be any additional artifacting produced from the compression.

And if you're looking to make for easy compression of an end product, Lanczos is not going to help the situation - it's designed to retain sharpness, which adds to the compression cost (meaning it'll need a higher bitrate to look good). You could try Bicubic or, if you prefer a softer-looking image, Bilinear resizing.

[Qyot27]

Gah, double-post.

In addition to the ringing artifacts produced by Lanczos, I also suspect it's getting exacerbated by the settings you're using in x264. Post your compression settings and the x264 revision number.