Blocky Backgrounds

[ArcticFox]

Im trying to archive my DVD collection for my Media Center pc to dvd resolution x264 with 5.1 AAC, the bitrate is hardly ever below 1000kbps and i use the HQ-Slower settings.

Now in most of my videos im getting terribly large blocks in the backgrounds, or in the sky but never on people. I dont have the fastest CPU around so wasting a night encoding something thats useless to me is very frustrating.

So has anyone figured out why the backgrounds go so blocky?

[AlexB17]

Check the "No fast P-skip" option - and enable it, if not checked - it helps alot! Sorry for bad english :(

[check]

the HQ-Slower setting by default uses a bitrate of 1000kbits 2pass. You can either increase the bitrate or set it to a CQ mode to help remove the blocks.

[bond]

also make sure that you are using a new compile of x264

[Sharktooth]

did you happen to disable the inloop deblocking (encoder or decoder)?

[Morte66]

Read this thread (http://forum.doom9.org/showthread.php?t=112968), in which I raised a similar problem.

So far as blocking is concerned, try these suggestions from that thread:

- Turn off MPEG2 deblocking in MeGUI/DGIndex, if you're using it. It makes the existing blocking more obvious and adds blocks of its own before you start encoding. This was far and away the biggest improvement I got.

- Use a custom matrix designed to reduce blocking within the encoder, like sharktooth's (moderate) or mp4guy's (stronger), and turn off prediction for B-Frames. This gave the second biggest difference.

- Turn on the x 264 "no-fast-pskip" option. It's mostly useful when you've got a perfect source -- the difference it makes is minor compared to the DVD imperfections you start with -- but you might as well use it.

- Have a look at the options for adding noise to hide blocky areas in the output, and see what you think. I was never happy for various reasons, but I could imagine that they might suit some people.

As for speed, a couple of things you should try:

- If you're encoding to a hard drive and don't really mind about exact file sizes, try constant quality encoding at about level 22. This will measure the error in the output as it goes along and adjust the bitrate to hit a constant quality level. It gives essentially the same output as two-pass encoding at the same bitrate would, but it's >50% faster.

- Put a statement like "trim(5000,6000)" in your avisynth script, which will give you ~40 second test clips to work out the settings you want before you do the full encode.

[markrb]

Morte66 you say to turn off Mpeg2 deblocking.
There are 2 places for that.
1. In the Avisynth script creator (simple check) and
2. in the main page of the x264 config of megui (strength and threshold settings).

Which are you refering to?

[Morte66]

Morte66 you say to turn off Mpeg2 deblocking.
There are 2 places for that.
1. In the Avisynth script creator (simple check) and
2. in the main page of the x264 config of megui (strength and threshold settings).

Which are you refering to?

The avisynth script creator on the "filters" tab. Also, if you use avisynth script profiles you might change it in those. Ultimately, you want to get rid of the "cpu=4" parameter from the source line in your avisynth script.

[quake74]

If I may add my suggestion, use adaptive quantization (--aq-strength and --aq-sensitivity). Usually for me --aq-strenght 0.75 helps a lot on low-contrast backgrounds.

[elguaxo]

If I may add my suggestion, use adaptive quantization (--aq-strength and --aq-sensitivity). Usually for me --aq-strenght 0.75 helps a lot on low-contrast backgrounds.
Is adaptive quantization available using x264/MeGUI? If not, is it possible to add '--aq-strength and --aq-sensitivity' to the commandline that MeGUI sends to x264?

Does x264 r534 support adaptive quantization?

Thanks.

[check]

You can always copy th commandline that MeGUI prouces and run it yourself from a .bat file. You can reveal the commandline by clicking the box at the bottom of the x264 settings page. Every pass will have a slightly different command line btw.

[elguaxo]

I do mostly 2 pass encodes using 'turbo' for the first pass. Do I need to add --aq-strength and --aq-sensitivity to the first pass too?

And does x264 r534 support adaptive quantization?

Thanks!

[Sharktooth]

the haali's AQ patch is still in my builds (their also what you get from megui auto-update).

[elguaxo]

Great!

And the last question. If I do 2 pass encodes using 'turbo', do I need to add --aq-strength and --aq-sensitivity to the first pass too? TIA

[thuongshoo]

I have a MPEG file which singers stand in the shade of a tree . Singers' face is scratched . I also try to use -aq-strength 1.1 but I still haven't a good result .
x264 seem not to be good at dark scene

[CruNcher]

@thuongshoo
is it a still scene so the area you see problems in is not moving ?
if yes please read this http://forum.doom9.org/showthread.php?p=853152#post853152
that's also the couse why X264 is not beta yet their still some Stability issues

[thuongshoo]

I have just converted the mpeg into xvid, divx by VD.
I havenot known the way to adjust paramters well yet for Xvid but I know some thing about DivX because DivX coder has no many parameter :D
Result is bad . Yes ! worst than x264 . I can't still convert this file by a good way . I often use --cfr 26 I can't use cfr 20 or belower because size of encoded file will be the same to orginal file :D

I often convert Xvid into x264. Artifact which is made by x264 is easy to viewer than Xvid. Xvid video often
have "spreading-oild-artifact" . Oh ! I dont' know which word I should use . Any English help me ? :)


I'm sorry because of my previous post ! That's only my guess ! :p. I don't want to tease anyone. :D

[lexor]

I am currently battling a similar problem, the insanely bloocky sky in LotR: The Two Towers, I use HQ-Slow with No-Fast-Skip turned on, and a bitrate of 3015kpbs for video (going for full DVD-5 for the 3hours of movie)

However aside from the horrid blooking (which thanx to foxy had been reduced when I turned off mpeg2 deblock) I now am faced with a problem that I'm not quite sure how to fix (turning off mpeg2 deblock wasn't the cause of it, in case you wondering). I get purple blocks on stationary blue sky, it's like a checker board pattern, but they turn on and off in several places (I guess the best analogy I can give is like those huge computers in the movies from 70s, with huge screens of blinking squares)

The purple blocks are completely out of place, there is nothing purple (or close to it) in the source. In fact I can't even find any noticable blocking in the source. I'm stumped, has anyone wrestled with this problem before?

I'm really disheartened by the amount of blooking at such high bitrate. My script uses only colormatrix (this doesn't affect purple blooks), deinterlace and undot.

[foxyshadis]

Is there any chance you can reproduce it on a 5 or 10 second clip, and upload that as lossless and encoded to examine?

[lexor]

Is there any chance you can reproduce it on a 5 or 10 second clip, and upload that as lossless and encoded to examine?
believe it or not, you actually helped me fix it right there! I encoded to Lossless, and got black output on playback, I went into the decoder options toggled options on and off and even though I put them back now exactly as they were, it now works for lossless and no purple blocks. ffdshow hickup... and I was about to pull my hair out. :eek:

:thanks:

now I'm off to battle the masquito-like noise that got introduced by encoder, it's like tiny moving blocks, I guess I'll give built in denoiser a go, never tried it before.

[ArcticFox]

Where do i turn off mpeg2 deblocking in megui i cant find it?

[lexor]

Where do i turn off mpeg2 deblocking in megui i cant find it?
it's in the avisynth creator (filters tab), but if you didn't turn it on by yourself, it's off, so you don't have to warry about it.